Effective Actions of Matrix Models on Homogeneous Spaces
Imai, T; Takayama, Y; Tomino, D
2002-01-01
We evaluate the effective actions of supersymmetric matrix models on fuzzy S^2times S^2 up to the two loop level. Remarkably it turns out to be a consistent solution of IIB matrix model. Based on the power counting and SUSY cancellation arguments, we can identify the 't Hooft coupling and large N scaling behavior of the effective actions to all orders. In the large N limit, the quantum corrections survive except in 2 dimensional limits. They are O(N) and O(N^{4over 3}) for 4 and 6 dimensional spaces respectively. We argue that quantum effects single out 4 dimensionality of space-time.
Tracking in Object Action Space
DEFF Research Database (Denmark)
Krüger, Volker; Herzog, Dennis
2013-01-01
In this paper we focus on the joint problem of tracking humans and recognizing human action in scenarios such as a kitchen scenario or a scenario where a robot cooperates with a human, e.g., for a manufacturing task. In these scenarios, the human directly interacts with objects physically by using....../manipulating them or by, e.g., pointing at them such as in “Give me that…”. To recognize these types of human actions is difficult because (a) they ought to be recognized independent of scene parameters such as viewing direction and (b) the actions are parametric, where the parameters are either object...... tracking and action recognition should be seen as an intertwined problem that is primed by the objects on which the actions are applied. In this paper, we are looking at human body tracking and action recognition from a object-driven perspective. Instead of the space of human body poses we consider...
Learning Actions Models: Qualitative Approach
DEFF Research Database (Denmark)
Bolander, Thomas; Gierasimczuk, Nina
2015-01-01
—they are identifiable in the limit.We then move on to a particular learning method, which proceeds via restriction of a space of events within a learning-specific action model. This way of learning closely resembles the well-known update method from dynamic epistemic logic. We introduce several different learning......In dynamic epistemic logic, actions are described using action models. In this paper we introduce a framework for studying learnability of action models from observations. We present first results concerning propositional action models. First we check two basic learnability criteria: finite...... identifiability (conclusively inferring the appropriate action model in finite time) and identifiability in the limit (inconclusive convergence to the right action model). We show that deterministic actions are finitely identifiable, while non-deterministic actions require more learning power...
Learning Actions Models: Qualitative Approach
DEFF Research Database (Denmark)
Bolander, Thomas; Gierasimczuk, Nina
2015-01-01
identifiability (conclusively inferring the appropriate action model in finite time) and identifiability in the limit (inconclusive convergence to the right action model). We show that deterministic actions are finitely identifiable, while non-deterministic actions require more learning power......—they are identifiable in the limit.We then move on to a particular learning method, which proceeds via restriction of a space of events within a learning-specific action model. This way of learning closely resembles the well-known update method from dynamic epistemic logic. We introduce several different learning...
Space Science in Action: Space Exploration [Videotape].
1999
In this videotape recording, students learn about the human quest to discover what is out in space. Students see the challenges and benefits of space exploration including the development of rocket science, a look back at the space race, and a history of manned space travel. A special section on the Saturn V rocket gives students insight into the…
Using Continuous Action Spaces to Solve Discrete Problems
van Hasselt, Hado; Wiering, Marco
2009-01-01
Real-world control problems are often modeled as Markov Decision Processes (MDPs) with discrete action spaces to facilitate the use of the many reinforcement learning algorithms that exist to find solutions for such MDPs. For many of these problems an underlying continuous action space can be assume
Using Continuous Action Spaces to Solve Discrete Problems
van Hasselt, Hado; Wiering, Marco
2009-01-01
Real-world control problems are often modeled as Markov Decision Processes (MDPs) with discrete action spaces to facilitate the use of the many reinforcement learning algorithms that exist to find solutions for such MDPs. For many of these problems an underlying continuous action space can be
Tracking in Object Action Space
DEFF Research Database (Denmark)
Krüger, Volker; Herzog, Dennis
2013-01-01
In this paper we focus on the joint problem of tracking humans and recognizing human action in scenarios such as a kitchen scenario or a scenario where a robot cooperates with a human, e.g., for a manufacturing task. In these scenarios, the human directly interacts with objects physically by using...
Affirmative action as organization development at the Johnson Space Center
Tryman, Mfanya Donald L.
1987-01-01
The role of affirmative actions is investigated as an interventionist Organization Development (OD) strategy for insuring equal opportunities at the NASA/Johnson Space Center. In doing so, an eclectic and holistic model is developed for the recruiting and hiring of minorities and females over the next five years. The strategy, approach, and assumptions for the model are quite different than those for JSC's five year plan. The study concludes that Organization development utilizing affirmative action is a valid means to bring about organizational change and renewal processes, and that an eclectic model of affirmative action is most suitable and rational in obtaining this end.
Learning Action Models: Qualitative Approach
Bolander, T.; Gierasimczuk, N.; van der Hoek, W.; Holliday, W.H.; Wang, W.-F.
2015-01-01
In dynamic epistemic logic, actions are described using action models. In this paper we introduce a framework for studying learnability of action models from observations. We present first results concerning propositional action models. First we check two basic learnability criteria: finite
Renormalization and Induced Gauge Action on a Noncommutative Space
Grosse, Harald
2007-01-01
Field theories on deformed spaces suffer from the IR/UV mxing and renormalization is generically spoiled. In work with R. Wulkenhaar, one of us realized a way to cure this desease by adding one more marginal operator. We review these ideas, show the application to $\\phi^3$ models and use heat kernel expansion methods for a scalar field theory coupled to an external gauge field on a $\\theta$-deformed space and derive noncommutative gauge actions.
Action Emulation between Canonical Models
D.J.N. van Eijck (Jan); F.A.G. Sietsma (Floor)
2012-01-01
textabstractIn this paper we investigate Kripke models, used to model knowledge or belief in a static situation, and action models, used to model communicative actions that change this knowledge or belief. The appropriate notion for structural equivalence between modal structures such as Kr
Active Affordance Learning in Continuous State and Action Spaces
Wang, C.; Hindriks, K.V.; Babuska, R.
2014-01-01
Learning object affordances and manipulation skills is essential for developing cognitive service robots. We propose an active affordance learning approach in continuous state and action spaces without manual discretization of states or exploratory motor primitives. During exploration in the action
National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes presentation materials and outputs from operational space environment models produced by the NOAA Space Weather Prediction Center (SWPC) and...
Noncommutative spaces from matrix models
Lu, Lei
theories on such backgrounds result from perturbations about the solutions. The perturbative analysis requires non-standard Seiberg-Witten maps which depend on the embeddings in the ambient space and the symplectic 2-form. We find interesting properties of the field theories in the commutative limit. For example, stability of the action may require adding symmetry breaking terms to the matrix action, along with a selected range for the matrix coefficients. In the second part of this dissertation, we study higher dimensional fuzzy spaces in a tensorial matrix model, which is a natural generalization to the three-dimensional actions and is valid in any number of space-time dimensions. Four-dimensional tensor product NC spaces can be constructed from two-dimensional NC spaces and may provide a setting for doing four-dimensional NC cosmology. Another solution to the tensorial matrix model equations of motion is the Snyder algebra. A crucial step in exploring NC physics is to understand the structure of the quantized space-time in terms of the group representations of the NC algebra. We therefore study the representation theory of the Snyder algebra and implementation of symmetry transformations on the resulted discrete lattices. We find the three-dimensional Snyder space to be associated with two distinct Hilbert spaces, which define two reducible representations of the su(2) x su(2) algebra. This implies the existence of two distinct lattice structures of Snyder space. The difference between the two representations is evident in the spectra of the position operators, which could only be integers in one case and half integers in the other case. We also show that despite the discrete nature of the Snyder space, continuous translations and rotations can be unitarily implemented on the lattices.
Stigmergy, collective actions, and animal social spacing.
Giuggioli, Luca; Potts, Jonathan R; Rubenstein, Daniel I; Levin, Simon A
2013-10-15
Collective animal behavior studies have led the way in developing models that account for a large number of individuals, but mostly have considered situations in which alignment and attraction play a key role, such as in schooling and flocking. By quantifying how animals react to one another's presence, when interaction is via conspecific avoidance rather than alignment or attraction, we present a mechanistic insight that enables us to link individual behavior and space use patterns. As animals respond to both current and past positions of their neighbors, the assumption that the relative location of individuals is statistically and history independent is not tenable, underscoring the limitations of traditional space use studies. We move beyond that assumption by constructing a framework to analyze spatial segregation of mobile animals when neighbor proximity may elicit a retreat, and by linking conspecific encounter rate to history-dependent avoidance behavior. Our approach rests on the knowledge that animals communicate by modifying the environment in which they live, providing a method to analyze social cohesion as stigmergy, a form of mediated animal-animal interaction. By considering a population of animals that mark the terrain as they move, we predict how the spatiotemporal patterns that emerge depend on the degree of stigmergy of the interaction processes. We find in particular that nonlocal decision rules may generate a nonmonotonic dependence of the animal encounter rate as a function of the tendency to retreat from locations recently visited by other conspecifics, which has fundamental implications for epidemic disease spread and animal sociality.
Introduction. Modelling natural action selection.
Prescott, Tony J; Bryson, Joanna J; Seth, Anil K
2007-09-29
Action selection is the task of resolving conflicts between competing behavioural alternatives. This theme issue is dedicated to advancing our understanding of the behavioural patterns and neural substrates supporting action selection in animals, including humans. The scope of problems investigated includes: (i) whether biological action selection is optimal (and, if so, what is optimized), (ii) the neural substrates for action selection in the vertebrate brain, (iii) the role of perceptual selection in decision-making, and (iv) the interaction of group and individual action selection. A second aim of this issue is to advance methodological practice with respect to modelling natural action section. A wide variety of computational modelling techniques are therefore employed ranging from formal mathematical approaches through to computational neuroscience, connectionism and agent-based modelling. The research described has broad implications for both natural and artificial sciences. One example, highlighted here, is its application to medical science where models of the neural substrates for action selection are contributing to the understanding of brain disorders such as Parkinson's disease, schizophrenia and attention deficit/hyperactivity disorder.
The New Space Weather Action Center; the Next Level on Space Weather Education
Collado-Vega, Y. M.; Lewis, E. M.; Cline, T. D.; MacDonald, E.
2016-12-01
The Space Weather Action Center (SWAC) provides access for students to near real-time space weather data, and a set of easy instructions and well-defined protocols that allow them to correctly interpret such data. It is a student centered approach to teaching science and technology in classrooms, as students are encouraged to act like real scientists by accessing, collecting, analyzing, recording, and communicating space weather forecasts. Integration and implementation of several programs will enhance and provide a rich education experience for students' grades 5-16. We will enhance the existing data and tutorials available using the Integrated Space Weather Analysis (iSWA) tool created by the Community Coordinated Modeling Center (CCMC) at NASA GSFC. iSWA is a flexible, turn-key, customer-configurable, Web-based dissemination system for NASA-relevant space weather information that combines data based on the most advanced space weather models available through the CCMC with concurrent space environment information. This tool provides an additional component by the use of videos and still imagery from different sources as a tool for educators to effectively show what happens during an eruption from the surface of the Sun. We will also update content on the net result of space weather forecasting that the public can experience by including Aurorasaurus, a well established, growing, modern, innovative, interdisciplinary citizen science project centered around the public's visibility of the northern lights with mobile applications via the use of social media connections.
Space for action: How practitioners influence environmental assessment
Energy Technology Data Exchange (ETDEWEB)
Kågström, Mari, E-mail: mari.kagstrom@slu.se [Department of Urban and Rural Development, Swedish University of Agricultural Sciences (Sweden); Richardson, Tim, E-mail: tim.richardson@nmbu.no [Department of Landscape Architecture and Spatial Planning, Norwegian University of Life Sciences, Frederik A Dahls vei 15, KA-bygningen, Ås (Norway)
2015-09-15
Highlights: • The concept of ‘space for action’ offers an important new lens on EA practice. • Focuses on the relation between practitioner's understanding and their actions • Environmental assessment practice is decisively shaped by practitioners. • Practitioners may underestimate their potential to make a difference. • Contributes to understanding change in the environmental assessment field. This article contributes to understanding of how change occurs in the field of environmental assessment (EA). It argues that the integration of new issues in EA, such as human health, is significantly influenced by how practitioners' understandings shape their actions, and by what happens when those, possibly different, interpretations of appropriate action are acted out. The concept of space for action is developed as a means of investigating this relation between understanding and action. Frame theory is also used, to develop a sharper focus on how ‘potential spaces for action’ are created, what these imply for (individuals') preferred choices and actions in certain situations, and what happens in practice when these are acted out and ‘actual spaces for action’ are created. This novel approach is then applied in a Swedish case study of transport planning. The analysis reveals the important work done by practitioners, revealing just how EA practice is decisively shaped by practitioners. Analysis of practice using the lens of spaces for action offers an important new perspective in understanding how the field adapts to new challenges.
Collective action and rationality models
Directory of Open Access Journals (Sweden)
Luis Miguel Miller Moya
2004-01-01
Full Text Available The Olsonian theory of collective action (Olson, 1965 assumes a model of economic rationality, based on a simple calculus between costs and benefits, that can be hardly hold at present, given the models of rationality proposed recently by several fields of research. In relation to these fields, I will concentrate in two specific proposals, namely: evolutionary game theory and, over all, the theory of bounded rationality. Both alternatives are specially fruitful in order to propose models that do not need a maximizing rationality, or environments of complete and perfect information. Their approaches, based on the possibility of individual learning over the time, have contributed to the analysis of the emergence of social norms, which is something really necessary to the resolution of problems related to cooperation. Thus, this article asserts that these two new theoretical contributions make feasible a fundamental advance in the study of collective action.
Others' Actions Reduce Crossmodal Integration in Peripersonal Space
Heed, T.; Habets, B.; Sebanz, N.; Knoblich, G.K.
2010-01-01
Specific mechanisms integrate visual-tactile information close to the body to guide voluntary action [1, 2] and to enable rapid self-defense in peripersonal space [3-5]. In social interactions, others frequently act in one's peripersonal space, thereby changing the relevance of near-body events for
Others' Actions Reduce Crossmodal Integration in Peripersonal Space
Heed, T.; Habets, B.; Sebanz, N.; Knoblich, G.K.
2010-01-01
Specific mechanisms integrate visual-tactile information close to the body to guide voluntary action [1, 2] and to enable rapid self-defense in peripersonal space [3-5]. In social interactions, others frequently act in one's peripersonal space, thereby changing the relevance of near-body events for
"Implicit action": Understanding discourse management in modeling instruction
Durden, Jared; Brewe, Eric; Kramer, Laird
2012-02-01
We present "Implicit Action", a discourse management tool, through a qualitative video analysis of a Florida International University Modeling Instruction Introductory Physics I class. Implicit Action in Modeling Instruction is where instructors deliberately create intellectual space in which students ideally see value and need for the construction of new classroom norms and tools that are productive in developing a learning community. This space is created by the implications expressed through the instructors' deliberate actions. Discourse Management is a technique to moderate student discourse in Modeling Instruction classes at the university level that was initially described by Desbien [1]. Implicit Action is one of 9 Modeling Discourse Management tools that we have identified. By means of qualitative analysis we illustrate the effectiveness of Implicit Action in implementing the Modeling Theory of Instruction.
Unsupervised action classification using space-time link analysis
DEFF Research Database (Denmark)
Liu, Haowei; Feris, Rogerio; Krüger, Volker
2010-01-01
In this paper we address the problem of unsupervised discovery of action classes in video data. Different from all existing methods thus far proposed for this task, we present a space-time link analysis approach which matches the performance of traditional unsupervised action categorization methods...... in a standard dataset. Our method is inspired by the recent success of link analysis techniques in the image domain. By applying these techniques in the space-time domain, we are able to naturally take into account the spatio-temporal relationships between the video features, while leveraging the power of graph...
Pro-Torus Actions on Poincaré Duality Spaces
Indian Academy of Sciences (India)
Ali Özkurt; Doğan Dönmez
2006-08-01
In this paper, it is shown that some of the results of torus actions on Poincaré duality spaces, Borel’s dimension formula and topological splitting principle to local weights, hold if `torus’ is replaced by `pro-torus’.
Schild Action and Space-Time Uncertainty Principle in String Theory
Yoneya, T
1997-01-01
We show that the path-integral quantization of relativistic strings with the Schild action is essentially equivalent to the usual Polyakov quantization at critical space-time dimensions. We then present an interpretation of the Schild action which points towards a derivation of superstring theory as a theory of quantized space-time where the squared string scale, $\\ell_s^2 \\sim \\alpha'$, plays the role of the minimum quantum for space-time areas. A tentative approach towards such a goal is proposed, based on a microcanonical formulation of large N supersymmetric matrix model.
Directory of Open Access Journals (Sweden)
Radivoyevitch Tomas
2009-12-01
Full Text Available Abstract Background Ribonucleotide reductase is the main control point of dNTP production. It has two subunits, R1, and R2 or p53R2. R1 has 5 possible catalytic site states (empty or filled with 1 of 4 NDPs, 5 possible s-site states (empty or filled with ATP, dATP, dTTP or dGTP, 3 possible a-site states (empty or filled with ATP or dATP, perhaps two possible h-site states (empty or filled with ATP, and all of this is folded into an R1 monomer-dimer-tetramer-hexamer equilibrium where R1 j-mers can be bound by variable numbers of R2 or p53R2 dimers. Trillions of RNR complexes are possible as a result. The problem is to determine which are needed in models to explain available data. This problem is intractable for 10 reactants, but it can be solved for 2 and is here for R1 and ATP. Results Thousands of ATP-induced R1 hexamerization models with up to three (s, a and h ATP binding sites per R1 subunit were automatically generated via hypotheses that complete dissociation constants are infinite and/or that binary dissociation constants are equal. To limit the model space size, it was assumed that s-sites are always filled in oligomers and never filled in monomers, and to interpret model terms it was assumed that a-sites fill before h-sites. The models were fitted to published dynamic light scattering data. As the lowest Akaike Information Criterion (AIC of the 3-parameter models was greater than the lowest of the 2-parameter models, only models with up to 3 parameters were fitted. Models with sums of squared errors less than twice the minimum were then partitioned into two groups: those that contained no occupied h-site terms (508 models and those that contained at least one (1580 models. Normalized AIC densities of these two groups of models differed significantly in favor of models that did not include an h-site term (Kolmogorov-Smirnov p -15; consistent with this, 28 of the top 30 models (ranked by AICs did not include an h-site term and 28
Modelling the control of interceptive actions
National Research Council Canada - National Science Library
P. J. Beek; J. C. Dessing; C. E. Peper; D. Bullock
2003-01-01
.... We call these short–route models as they do not address how perception–action patterns might be constrained by the dynamical properties of the sensory, neural and musculoskeletal subsystems of the human action system...
A Note on the Derivation of Wave Action Balance Equation in Frequency Space
Institute of Scientific and Technical Information of China (English)
Tai-Wen HSU; Jian-Ming LIAU; Shin-Jye LIANG; Shan-Hwei OU; Yi-Ting LI
2011-01-01
In this paper the wave action balance equation in terms of frequency-direction spectrum is derived.A theoretical formulation is presented to generate an invariant frequency space to replace the varying wavenumber space through a Jacobian transformation in the wave action balance equation.The physical properties of the Jacobian incorporating the effects of water depths are discussed.The results provide a theoretical basis of wave action balance equations and ensure that the wave balance equations used in the SWAN or other numerical models are correct.It should be noted that the Jacobian is omitted in the wave action balance equations which are identical to a conventional action balance equation.
Vangeneugden, Joris; Pollick, Frank; Vogels, Rufin
2009-03-01
Neurons in the rostral superior temporal sulcus (STS) are responsive to displays of body movements. We employed a parametric action space to determine how similarities among actions are represented by visual temporal neurons and how form and motion information contributes to their responses. The stimulus space consisted of a stick-plus-point-light figure performing arm actions and their blends. Multidimensional scaling showed that the responses of temporal neurons represented the ordinal similarity between these actions. Further tests distinguished neurons responding equally strongly to static presentations and to actions ("snapshot" neurons), from those responding much less strongly to static presentations, but responding well when motion was present ("motion" neurons). The "motion" neurons were predominantly found in the upper bank/fundus of the STS, and "snapshot" neurons in the lower bank of the STS and inferior temporal convexity. Most "motion" neurons showed strong response modulation during the course of an action, thus responding to action kinematics. "Motion" neurons displayed a greater average selectivity for these simple arm actions than did "snapshot" neurons. We suggest that the "motion" neurons code for visual kinematics, whereas the "snapshot" neurons code for form/posture, and that both can contribute to action recognition, in agreement with computation models of action recognition.
Sigma-Model Solitons on Noncommutative Spaces
Dabrowski, Ludwik; Landi, Giovanni; Luef, Franz
2015-12-01
We use results from time-frequency analysis and Gabor analysis to construct new classes of sigma-model solitons over the Moyal plane and over noncommutative tori, taken as source spaces, with a target space made of two points. A natural action functional leads to self-duality equations for projections in the source algebra. Solutions, having nontrivial topological content, are constructed via suitable Morita duality bimodules.
A model for configuration spaces of points
Campos, Ricardo; Willwacher, Thomas
2016-01-01
The configuration space of points on a $D$-dimensional smooth framed manifold may be compactified so as to admit a right action over the framed little $D$-disks operad. We construct a real combinatorial model for these modules, for compact smooth manifolds without boundary.
Conformal Higher Spin Theory and Twistor Space Actions
Haehnel, Philipp
2016-01-01
We consider the twistor description of conformal higher spin theories and give twistor space actions for the self-dual sector of theories with spin greater than two that produce the correct flat space-time spectrum. We identify a ghost-free subsector, analogous to the embedding of Einstein gravity with cosmological constant in Weyl gravity, which generates the unique spin-s three-point anti-MHV amplitude consistent with Poincare invariance and helicity constraints. By including interactions between the infinite tower of higher-spin fields we give a geometric interpretation to the twistor equations of motion as the integrability condition for a holomorphic structure on an infinite jet bundle. Finally, we introduce anti-self-dual interaction terms to define a twistor action for the full conformal higher spin theory.
Affine and degenerate affine BMW algebras: Actions on tensor space
Daugherty, Zajj; Virk, Rahbar
2012-01-01
The affine and degenerate affine Birman-Murakami-Wenzl (BMW) algebras arise naturally in the context of Schur-Weyl duality for orthogonal and symplectic quantum groups and Lie algebras, respectively. Cyclotomic BMW algebras, affine and cyclotomic Hecke algebras, and their degenerate versions are quotients. In this paper we explain how the affine and degenerate affine BMW algebras are tantalizers (tensor power centralizer algebras) by defining actions of the affine braid group and the degenerate affine braid algebra on tensor space and showing that, in important cases, these actions induce actions of the affine and degenerate affine BMW algebras. We then exploit the connection to quantum groups and Lie algebras to determine universal parameters for the affine and degenerate affine BMW algebras. Finally, we show that the universal parameters are central elements--the higher Casimir elements for orthogonal and symplectic enveloping algebras and quantum groups.
Autocratic strategies for iterated games with arbitrary action spaces.
McAvoy, Alex; Hauert, Christoph
2016-03-29
The recent discovery of zero-determinant strategies for the iterated prisoner's dilemma sparked a surge of interest in the surprising fact that a player can exert unilateral control over iterated interactions. These remarkable strategies, however, are known to exist only in games in which players choose between two alternative actions such as "cooperate" and "defect." Here we introduce a broader class of autocratic strategies by extending zero-determinant strategies to iterated games with more general action spaces. We use the continuous donation game as an example, which represents an instance of the prisoner's dilemma that intuitively extends to a continuous range of cooperation levels. Surprisingly, despite the fact that the opponent has infinitely many donation levels from which to choose, a player can devise an autocratic strategy to enforce a linear relationship between his or her payoff and that of the opponent even when restricting his or her actions to merely two discrete levels of cooperation. In particular, a player can use such a strategy to extort an unfair share of the payoffs from the opponent. Therefore, although the action space of the continuous donation game dwarfs that of the classic prisoner's dilemma, players can still devise relatively simple autocratic and, in particular, extortionate strategies.
Autonomous mental development in high dimensional context and action spaces.
Joshi, Ameet; Weng, Juyang
2003-01-01
Autonomous Mental Development (AMD) of robots opened a new paradigm for developing machine intelligence, using neural network type of techniques and it fundamentally changed the way an intelligent machine is developed from manual to autonomous. The work presented here is a part of SAIL (Self-Organizing Autonomous Incremental Learner) project which deals with autonomous development of humanoid robot with vision, audition, manipulation and locomotion. The major issue addressed here is the challenge of high dimensional action space (5-10) in addition to the high dimensional context space (hundreds to thousands and beyond), typically required by an AMD machine. This is the first work that studies a high dimensional (numeric) action space in conjunction with a high dimensional perception (context state) space, under the AMD mode. Two new learning algorithms, Direct Update on Direction Cosines (DUDC) and High-Dimensional Conjugate Gradient Search (HCGS), are developed, implemented and tested. The convergence properties of both the algorithms and their targeted applications are discussed. Autonomous learning of speech production under reinforcement learning is studied as an example.
Space market model space industry input-output model
Hodgin, Robert F.; Marchesini, Roberto
1987-01-01
The goal of the Space Market Model (SMM) is to develop an information resource for the space industry. The SMM is intended to contain information appropriate for decision making in the space industry. The objectives of the SMM are to: (1) assemble information related to the development of the space business; (2) construct an adequate description of the emerging space market; (3) disseminate the information on the space market to forecasts and planners in government agencies and private corporations; and (4) provide timely analyses and forecasts of critical elements of the space market. An Input-Output model of market activity is proposed which are capable of transforming raw data into useful information for decision makers and policy makers dealing with the space sector.
Action-angle variables for complex projective space and semiclassical exactness
Oh, P; Phillial Oh; Myung-Ho Kim
1994-01-01
We construct the action-angle variables of a classical integrable model defined on complex projective phase space and calculate the quantum mechanical propagator in the coherent state path integral representation using the stationary phase approximation. We show that the resulting expression for the propagator coincides with the exact propagator which was obtained by solving the time-dependent Schr\\"odinger equation.
The What, Who, and How of Ecological Action Space
Directory of Open Access Journals (Sweden)
Karin Skill
2011-12-01
Full Text Available This text presents an analytical concept which is aimed at analysis of the construction of environmental responsibility—ecological action space. The concept makes it possible to analyze what environmental activities householders perform, who takes on the environmental responsibility, and how they motivate and justify everyday practices in relation to other actors. The concept builds on structuration theory, and is useful in studies of sustainable development in everyday life, and in investigations about how actors perceive their role in creating and solving environmental problems, and what actions they take in light of this. The concept should be used for empirical rather than normative studies. Relevant questions for a study about ecological action space are: What activities are considered environmentally friendly? How do the actors conceive of their opportunities to act in environmentally friendly ways and what constraints do they express? These questions are relevant not just for outspoken activists. When promoting increased participation, it is valuable to discuss when, where and how people are expected to get involved.
Peculiarities of biological action of hadrons of space radiation.
Akoev, I G; Yurov, S S
1975-01-01
Biological investigations in space enable one to make a significant contribution on high-energy hadrons to biological effects under the influence of factors of space flights. Physical and molecular principles of the action of high-energy hadrons are analysed. Genetic and somatic hadron effects produced by the secondary radiation from 70 GeV protons have been studied experimentally. The high biological effectiveness of hadrons, great variability in biological effects, and specifically of their action, are associated with strong interactions of high-energy hadrons. These are the probability of nuclear interaction with any atom nucleus, generation of a great number of secondary particles (among them, probably, highly effective multicharged and heavy nuclei, antiprotons, pi(-)-mesons), and the spatial distribution of secondary particles as a narrow cone with extremely high density of particles in its first part. The secondary radiation generated by high- and superhigh-energy hadrons upon their interaction with the spaceship is likely to be the greatest hazard of radiation to the crew during space flights.
Developing a Model for Continuous Professional Development by Action Research
Herbert, Susan; Rainford, Marcia
2014-01-01
This paper presents a case study of the work of two teacher educators with an in-service science teacher. This case study forms one cycle of a larger action research study that will eventually lead to a model of how the third-space concept for teacher professional development can be realized in natural school settings. The case study took place in…
Embedding a State Space Model Into a Markov Decision Process
DEFF Research Database (Denmark)
Nielsen, Lars Relund; Jørgensen, Erik; Højsgaard, Søren
2011-01-01
estimated from data collected from the animal or herd. State space models (SSMs) are a general tool for modeling repeated measurements over time where the model parameters can evolve dynamically. In this paper we consider methods for embedding an SSM into an MDP with finite state and action space. Different...
Public space and free action: Foucault vs. Lefebvre
Directory of Open Access Journals (Sweden)
Prodanović Srđan
2012-01-01
Full Text Available In this paper we will try to offer a systematic insight into the relation of everyday practices and public space. By examining the work of two of the most influential authors in this field, Foucault and Lefebvre, we will try to provide a theoretical explanation of intuition that (public space represents one of the key constitutive elements of free action. In the first part of the paper, we will consider Foucault’s notion of heterotopia in the interest of pointing towards a “spatially intermediated” self-reflection which, to a great degree, resembles the philosophical askesis form his so called letter work. Afterwards, we will consider in which sense Lefebvre’s position that public space represents a Hegelian concrete abstraction - which entails dialectical analysis and tracking of complex historical contradictions - complements and deepens perspective that Foucault puts before us in his heterotopias. In that vein, it will be shown that both authors, despite the difference in their theoretical starting points, defend the idea of such a public space in which all signifiers are removed in the interest of „opening space” for the free agent. [Projekat Ministarstva nauke Republike Srbije, br. 41004 i br. 43007
Sorokina, Svetlana; Zaichkina, Svetlana; Rozanova, Olga; Aptikaeva, Gella; Romanchenko, Sergei; Smirnova, Helene; Dyukina, Alsu; Peleshko, Vladimir
At present time little is known concerning the biological effects of low-dose-rate high-LET radiation exposure in space. The currently available experimental data on the biological effect of low doses of chronic radiation with high-LET values, which occur under the conditions of aircraft and space flights, have been primarily obtained in the examinations of pilots and astronauts after flights. Another way of obtaining this kind of evidence is the simulation of irradiation conditions during aircraft and space flights on high-energy accelerators and the conduction of large-scale experiments on animals under these conditions on Earth. In the present work, we investigated the cytogenetic effects of low-dose-rate high-LET radiation in the dose ranges of 0.2-30 cGy (1 cGy/day) and 0.5-16 cGy (0.43 cGy/day) in the radiation field behind the concrete shield of the Serpukhov accelerator of 70 GeV protons that simulates the spectral and component composition of radiation fields formed in the conditions of high-altitude flights on SHK mice in vivo. The dose dependence, adaptive response (AR) and the growth of solid tumor were examined. For induction of AR, two groups of mice were exposed to adapting doses of 0.2-30 cGy and the doses of 0.5-16 cGy of high-LET radiation. For comparison, third group of mice from unirradiated males was chronically irradiated with X-rays at adapting doses of 10 cGy (1 cGy/day). After a day, the mice of all groups were exposed to a challenging dose of 1.5 Gy of X-rays (1 Gy/min). After 28 h, the animals of all groups were killed by the method of cervical dislocation. Bone marrow specimens for calculating micronuclei (MN) in polychromatic erythrocytes (PCE) were prepared by a conventional method with minor modifications. The influence of adapting dose of 16 cGy on the growth of solid tumor of Ehrlich ascite carcinoma was estimated by measuring the size of the tumor at different times after the inoculation of ascitic cells s.c. into the femur. It was
Simplicial models for trace spaces
DEFF Research Database (Denmark)
Raussen, Martin
motivation stems from certain models for concurrent computation. So far, spaces of d-paths and their topological invariants have only been determined in cases that were elementary to overlook. In this paper, we develop a systematic approach describing spaces of directed paths - up to homotopy equivalence...... - as prodsimplicial complexes (with products of simplices as building blocks). This method makes use of certain poset categories of binary matrices and applies to a class of directed spaces that arise from a class of models of computation; still restricted but with a fair amount of generality. In the final section......, we outline a generalization to model spaces known as Higher Dimensional Automata. In particular, we describe algorithms that allow to determine not only the fundamental category of such amodel space, but all homological invariants of spaces of directed paths within it. The prodsimplical complexes...
Awareness, Solidarity, and Action: An Educational Model
Reichenbach, Michael R.
2016-01-01
How Extension fosters social change and innovation can be improved through the use of theory-based educational models. Educational models can serve as foundations for the conceptual designs of educational interventions. I describe, using examples from my own work, one such model: the awareness, solidarity, and action model. This three-part model…
Awareness, Solidarity, and Action: An Educational Model
Reichenbach, Michael R.
2016-01-01
How Extension fosters social change and innovation can be improved through the use of theory-based educational models. Educational models can serve as foundations for the conceptual designs of educational interventions. I describe, using examples from my own work, one such model: the awareness, solidarity, and action model. This three-part model…
Space Flight Cable Model Development
Spak, Kaitlin
2013-01-01
This work concentrates the modeling efforts presented in last year's VSGC conference paper, "Model Development for Cable-Harnessed Beams." The focus is narrowed to modeling of space-flight cables only, as a reliable damped cable model is not yet readily available and is necessary to continue modeling cable-harnessed space structures. New experimental data is presented, eliminating the low-frequency noise that plagued the first year's efforts. The distributed transfer function method is applied to a single section of space flight cable for Euler-Bernoulli and shear beams. The work presented here will be developed into a damped cable model that can be incorporated into an interconnected beam-cable system. The overall goal of this work is to accurately predict natural frequencies and modal damping ratios for cabled space structures.
Space debris: modeling and detectability
Wiedemann, C.; Lorenz, J.; Radtke, J.; Kebschull, C.; Horstmann, A.; Stoll, E.
2017-01-01
High precision orbit determination is required for the detection and removal of space debris. Knowledge of the distribution of debris objects in orbit is necessary for orbit determination by active or passive sensors. The results can be used to investigate the orbits on which objects of a certain size at a certain frequency can be found. The knowledge of the orbital distribution of the objects as well as their properties in accordance with sensor performance models provide the basis for estimating the expected detection rates. Comprehensive modeling of the space debris environment is required for this. This paper provides an overview of the current state of knowledge about the space debris environment. In particular non-cataloged small objects are evaluated. Furthermore, improvements concerning the update of the current space debris model are addressed. The model of the space debris environment is based on the simulation of historical events, such as fragmentations due to explosions and collisions that actually occurred in Earth orbits. The orbital distribution of debris is simulated by propagating the orbits considering all perturbing forces up to a reference epoch. The modeled object population is compared with measured data and validated. The model provides a statistical distribution of space objects, according to their size and number. This distribution is based on the correct consideration of orbital mechanics. This allows for a realistic description of the space debris environment. Subsequently, a realistic prediction can be provided concerning the question, how many pieces of debris can be expected on certain orbits. To validate the model, a software tool has been developed which allows the simulation of the observation behavior of ground-based or space-based sensors. Thus, it is possible to compare the results of published measurement data with simulated detections. This tool can also be used for the simulation of sensor measurement campaigns. It is
Space market model development project
Bishop, Peter C.
1987-01-01
The objectives of the research program, Space Market Model Development Project, (Phase 1) were: (1) to study the need for business information in the commercial development of space; and (2) to propose a design for an information system to meet the identified needs. Three simultaneous research strategies were used in proceeding toward this goal: (1) to describe the space business information which currently exists; (2) to survey government and business representatives on the information they would like to have; and (3) to investigate the feasibility of generating new economical information about the space industry.
Model space of economic events
Romanovsky, M. Yu.
A method for constructing the model or virtual space of economic events when economic objects can be considered as material ones is suggested. We describe change of share rates in time at stock markets as the potential difference of attracted bodies in time in this virtual space. Each share of each enterprise is displayed by a single particle with a unit “charge”. It is shown that the random value of potential difference at the origin of coordinates measured at a definite time interval has the probability density coinciding with the known distribution of “Levy flights” or “Levy walks”. A distribution of alteration in time of the “Standard and Poor” index value obtained by Mantegna and Stanley (they shown that it is the “Levy walks” distribution too) (Mantegna and Stanley, Nature 376 (1995) 46) is used for determination of the introduced potential dependence on coordinates in the model space. A simple phenomenological model of interaction potential is introduced. The potential law of each particle turns out to be closed to r-2.14 in the minimum possible three-dimensional model space. This model permits calculation of time of random potential correlations at a certain point of the model space. These correlations could characterize the time period of making a decision by an investor at stock exchange. It is shown that this time is notably shorter in unstable periods (1987). A “microscopical” model of interaction in the virtual space is also discussed.
Action principles for extended magnetohydrodynamic models
Energy Technology Data Exchange (ETDEWEB)
Keramidas Charidakos, I.; Lingam, M.; Morrison, P. J.; White, R. L. [Institute for Fusion Studies and Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States); Wurm, A. [Department of Physical and Biological Sciences, Western New England University, Springfield, Massachusetts 01119 (United States)
2014-09-15
The general, non-dissipative, two-fluid model in plasma physics is Hamiltonian, but this property is sometimes lost or obscured in the process of deriving simplified (or reduced) two-fluid or one-fluid models from the two-fluid equations of motion. To ensure that the reduced models are Hamiltonian, we start with the general two-fluid action functional, and make all the approximations, changes of variables, and expansions directly within the action context. The resulting equations are then mapped to the Eulerian fluid variables using a novel nonlocal Lagrange-Euler map. Using this method, we recover Lüst's general two-fluid model, extended magnetohydrodynamic (MHD), Hall MHD, and electron MHD from a unified framework. The variational formulation allows us to use Noether's theorem to derive conserved quantities for each symmetry of the action.
Hollows, Kerrilee; Fritzon, Katarina
2012-10-01
This study aimed to address the limitations of the existing genocide literature with the development of an empirically based classification system. Using Shye's (1985) action systems model, it was hypothesized that four types of perpetrators would exist and would be distinguishable by differences in the sources and target of individual criminal actions. Court transcripts from 80 perpetrators sentenced by the international courts were subject to content analysis and revealed 39 offense action variables, 17 perpetrator characteristic variables, and 6 perpetrator motive variables. A smallest space analysis using the Jaccard coefficient of association was conducted on the offense variables. The results supported the proposed framework, producing four distinct types of genocidal perpetrators. Correlational analyses were then conducted to examine the relationships between each of the perpetrator types and the remaining variables. The results of those correlations provided further support for the proposed framework. The implications of these findings are discussed. PsycINFO Database Record (c) 2012 APA, all rights reserved.
Huth, Alexander G; Nishimoto, Shinji; Vu, An T; Gallant, Jack L
2012-12-20
Humans can see and name thousands of distinct object and action categories, so it is unlikely that each category is represented in a distinct brain area. A more efficient scheme would be to represent categories as locations in a continuous semantic space mapped smoothly across the cortical surface. To search for such a space, we used fMRI to measure human brain activity evoked by natural movies. We then used voxelwise models to examine the cortical representation of 1,705 object and action categories. The first few dimensions of the underlying semantic space were recovered from the fit models by principal components analysis. Projection of the recovered semantic space onto cortical flat maps shows that semantic selectivity is organized into smooth gradients that cover much of visual and nonvisual cortex. Furthermore, both the recovered semantic space and the cortical organization of the space are shared across different individuals.
Action scales for decoherence and their relation to structures in phase space
Alonso, D; Palao, J P; Mayato, R S; Alonso, Daniel; Palao, Jose P.
2003-01-01
A characteristic action $\\Delta S$ is defined whose magnitude determines the basic properties of the mean expectation value of a general displacement in phase space. These properties are related to the capability of a given environmental `monitoring' system to induce decoherence in arbitrary quantum systems coupled to it by a broad kind of interactions. We show that according to this quantity the scale for effective decoherence is given by $\\Delta S \\gtrsim\\hbar$. This characteristic action is compared with another previously defined quantity \\cite{zurek2001}, and its connection with the main features of the pattern of structures developed by the different phase space representations of the environmental state is analyzed. The relevance of $\\Delta S$ is illustrated both numerically and by analyzing a set of model quantum systems whose classical analog is chaotic, for which the Berry-Voros conjecture is valid, and where analytical expressions for the mean expectation value of the displacement are obtained expl...
Modelling the control of interceptive actions.
Beek, P J; Dessing, J C; Peper, C E; Bullock, D
2003-09-29
In recent years, several phenomenological dynamical models have been formulated that describe how perceptual variables are incorporated in the control of motor variables. We call these short-route models as they do not address how perception-action patterns might be constrained by the dynamical properties of the sensory, neural and musculoskeletal subsystems of the human action system. As an alternative, we advocate a long-route modelling approach in which the dynamics of these subsystems are explicitly addressed and integrated to reproduce interceptive actions. The approach is exemplified through a discussion of a recently developed model for interceptive actions consisting of a neural network architecture for the online generation of motor outflow commands, based on time-to-contact information and information about the relative positions and velocities of hand and ball. This network is shown to be consistent with both behavioural and neurophysiological data. Finally, some problems are discussed with regard to the question of how the motor outflow commands (i.e. the intended movement) might be modulated in view of the musculoskeletal dynamics.
Ribstein, Bruno; Achatz, Ulrich; Senf, Fabian
2014-05-01
abstract Gravity waves (GWs) and solar tides (STs) are main constituents of the dynamical coupling between troposphere and mesosphere-lower-thermosphere (MLT). Via momentum deposition, GWs control to a large extent the mesospheric mean circulation. STs are large scale waves, mostly due to tropospheric and stratospheric diurnal heating processes, that modulate all dynamical fields in the mesosphere. GWs ant STs also interact strongly with each other. Conventional GW parameterizations used to describe this interaction (e.g. [1]) neglect the time-dependence and horizontal gradients of the background flow, with fatal effects (e.g. [2]). We study here the propagation of GWs in a time-dependent middle-atmosphere background flow, using a new (caustics free) WKB GW model (ray tracer). The background flow is composed by a climatological mean and tidal fields extracted from a general circulation model (HAMMONIA, see [3]). In order to avoid caustics, inevitable in classic ray-tracer implementations, we implemented a new wave-action phase-space density conservation scheme [4, 5]. The scheme attaches to each ray a finite volume in the location & wavenumber phase-space. The location-wavenumber volume is conserved during the propagation, responding in shape to the local stretching and squeezing in wave-number space. From the propagation of GWs we evaluate the deposition of momentum and buoyancy. Rayleigh-friction and temperature-relaxation coefficients are also evaluated. In this extension of the study by [2] it is shown, with an amplitude scheme more stable against numerical instabilities, due to the avoidance of caustics, that STs (and so the time dependence of the background flow) modulate the propagation of GWs. Via Rayleigh-friction and temperature-relaxation coefficients, we also quantify how the pseudo-momentum-, momentum-, and enthalpy-deposition of GWs can influence the amplitude and the phase structure of STs. Finally, we compare momentum and buoyancy fluxes from the
Directory of Open Access Journals (Sweden)
Belehaki Anna
2014-01-01
Full Text Available COST Action ES0803 “Developing Space Weather products and services in Europe” primarily aimed at forming an interdisciplinary network among European scientists dealing with different issues relevant to Geospace as well as warning system developers and operators in order to assess existing Space Weather products and recommend new ones. The work that has been implemented from 2008 to 2012 resulted in advances in modeling and predicting Space Weather, in recommendations for the validation of Space Weather models, in proposals for new Space Weather products and services, and in dissemination, training, and outreach activities. This preface summarizes the most important achievements of this European activity that are detailed in this special issue by the key scientists who participated in COST Action ES0803.
Effective Actions of IIB Matrix Model on S^3
Kaneko, Hiromichi; Matsumoto, Koichiro
2007-01-01
S^3 is a simple principle bundle which is locally S^2 \\times S^1. It has been shown that such a space can be constructed in terms of matrix models. It has been also shown that such a space can be realized by a generalized compactification procedure in the S^1 direction. We investigate the effective action of supersymmetric gauge theory on S^3 with an angular momentum cutoff and that of a matrix model compactification. The both cases can be realized in a deformed IIB matrix model with a Myers Term. We find that the highly divergent contributions at the tree and one loop level are sensitive to the uv cutoff. However the two loop level contributions are universal since they are only logarithmically divergent. We expect that the higher loop contributions are insensitive to the uv cutoff since 3d gauge theory is super renormalizable.
Directory of Open Access Journals (Sweden)
Narottam Maity
2016-01-01
Full Text Available Reflection of longitudinal displacement waves in a generalized thermoelastic half space under the action of uniform magnetic field has been investigated. The magnetic field is applied in such a direction that the problem can be considered as a two-dimensional one. The discussion is based on the three theories of generalized thermoelasticity: Lord-Shulman (L-S, Green-Lindsay (G-L, and Green-Naghdi (G-N with energy dissipation. We compute the possible wave velocities for different models. Amplitude ratios have been presented. The effects of magnetic field on various subjects of interest are discussed and shown graphically.
SpaceNet: Modeling and Simulating Space Logistics
Lee, Gene; Jordan, Elizabeth; Shishko, Robert; de Weck, Olivier; Armar, Nii; Siddiqi, Afreen
2008-01-01
This paper summarizes the current state of the art in interplanetary supply chain modeling and discusses SpaceNet as one particular method and tool to address space logistics modeling and simulation challenges. Fundamental upgrades to the interplanetary supply chain framework such as process groups, nested elements, and cargo sharing, enabled SpaceNet to model an integrated set of missions as a campaign. The capabilities and uses of SpaceNet are demonstrated by a step-by-step modeling and simulation of a lunar campaign.
SpaceNet: Modeling and Simulating Space Logistics
Lee, Gene; Jordan, Elizabeth; Shishko, Robert; de Weck, Olivier; Armar, Nii; Siddiqi, Afreen
2008-01-01
This paper summarizes the current state of the art in interplanetary supply chain modeling and discusses SpaceNet as one particular method and tool to address space logistics modeling and simulation challenges. Fundamental upgrades to the interplanetary supply chain framework such as process groups, nested elements, and cargo sharing, enabled SpaceNet to model an integrated set of missions as a campaign. The capabilities and uses of SpaceNet are demonstrated by a step-by-step modeling and simulation of a lunar campaign.
Benchmarking Ionizing Space Environment Models
Bourdarie, S.; Inguimbert, C.; Standarovski, D.; Vaillé, J.-R.; Sicard-Piet, A.; Falguere, D.; Ecoffet, R.; Poivey, C.; Lorfèvre, E.
2017-08-01
In-flight feedback data are collected, such as displacement damage doses, ionizing doses, and cumulated Single Event upset (SEU) on board various space vehicles and are compared to predictions performed with: 1) proton measurements performed with spectrometers data on board the same spacecraft if any and 2) protons spectrum predicted by the legacy AP8min model and the AP9 and Onera Proton Altitude Low models. When an accurate representation of the 3-D spacecraft shielding as well as appropriate ground calibrations are considered in the calculations, such comparisons provide powerful metrics to investigate engineering model accuracy. To describe >30 MeV trapped protons fluxes, the AP8 min model is found to provide closer predictions to observations than AP9 V1.30.001 (mean and perturbed mean).
Space-Time Structures from IIB Matrix Model
Aoki, H; Kawai, H; Kitazawa, Y; Tada, T
1998-01-01
We derive a long distance effective action for space-time coordinates from a IIB matrix model. It provides us an effective tool to study the structures of space-time. We prove the finiteness of the theory for finite $N$ to all orders of the perturbation theory. Space-time is shown to be inseparable and its dimensionality is dynamically determined. The IIB matrix model contains a mechanism to ensure the vanishing cosmological constant which does not rely on the manifest supersymmetry. We discuss possible mechanisms to obtain realistic dimensionality and gauge groups from the IIB matrix model.
Sculpting the space of actions: explaining human action by integrating intentions and mechanisms
Keestra, M.
2014-01-01
How can we explain the intentional nature of an expert’s actions, performed without immediate and conscious control, relying instead on automatic cognitive processes? How can we account for the differences and similarities with a novice’s performance of the same actions? Can a naturalist explanation
Spectral Action Models of Gravity on Packed Swiss Cheese Cosmology
Ball, Adam
2015-01-01
We present a model of (modified) gravity on spacetimes with fractal structure based on packing of spheres, which are (Euclidean) variants of the Packed Swiss Cheese Cosmology models. As the action functional for gravity we consider the spectral action of noncommutative geometry, and we compute its asymptotic expansion on a space obtained as an Apollonian packing of 3-dimensional spheres inside a 4-dimensional ball. Using information from the zeta function of the Dirac operator of the spectral triple, we show that the leading terms in the asymptotic expansion of the spectral action consist of a zeta regularization of the divergent sum of the leading terms of the spectral actions of the individual spheres in the packing, which accounts for the contribution of the points 1 and 3 in the dimension spectrum (as in the case of a 3-sphere). There is also an additional term coming from the residue at the additional point in the dimension spectrum that corresponds to the packing constant. It detects the fractality of t...
Effective action for a quantum scalar field in warped spaces
Energy Technology Data Exchange (ETDEWEB)
Hoff da Silva, J.M.; Mendonca, E.L.; Scatena, E. [Universidade Estadual Paulista ' ' Julio de Mesquita Filho' ' -UNESP, Departamento de Fisica e Quimica, Guaratingueta, SP (Brazil)
2015-11-15
We investigate the one-loop corrections, at zero as well as finite temperature, of a scalar field taking place in a braneworld motivated warped background. After to reach a well-defined problem, we calculate the effective action with the corresponding quantum corrections to each case. (orig.)
Type II chiral affine Lie algebras and string actions in doubled space
Hatsuda, Machiko; Siegel, Warren
2015-01-01
We present affine Lie algebras generated by the supercovariant derivatives and the supersymmetry generators for the left and right moving modes in the doubled space. Chirality is manifest in our doubled space as well as the T-duality symmetry. We present gauge invariant bosonic and superstring actions preserving the two-dimensional diffeomorphism invariance and the kappa-symmetry where doubled spacetime coordinates are chiral fields. The doubled space becomes the usual space by dimensional reduction constraints.
The Space Laser Business Model
2005-01-01
Creating long-duration, high-powered lasers, for satellites, that can withstand the type of optical misalignment and damage dished out by the unforgiving environment of space, is work that is unique to NASA. It is complicated, specific work, where each step forward is into uncharted territory. In the 1990s, as this technology was first being created, NASA gave free reign to a group of "laser jocks" to develop their own business model and supply the Space Agency with the technology it needed. It was still to be a part of NASA as a division of Goddard Space Flight Center, but would operate independently out of a remote office. The idea for this satellite laboratory was based on the Skunk Works concept at Lockheed Martin Corporation. Formerly known as the Lockheed Corporation, in 1943, the aerospace firm, realizing that the type of advanced research it needed done could not be performed within the confines of a larger company, allowed a group of researchers and engineers to essentially run their own microbusiness without the corporate oversight. The Skunk Works project, in Burbank, California, produced America s first jet fighter, the world s most successful spy plane (U-2), the first 3-times-the-speed-of-sound surveillance aircraft, and the F-117A Nighthawk Stealth Fighter. Boeing followed suit with its Phantom Works, an advanced research and development branch of the company that operates independent of the larger unit and is responsible for a great deal of its most cutting-edge research. NASA s version of this advanced business model was the Space Lidar Technology Center (SLTC), just south of Goddard, in College Park, Maryland. Established in 1998 under a Cooperative Agreement between Goddard and the University of Maryland s A. James Clark School of Engineering, it was a high-tech laser shop where a small group of specialists, never more than 20 employees, worked all hours of the day and night to create the cutting- edge technology the Agency required of them. Drs
Developing an Action Learning Design Model
Bong, Hyeon-Cheol; Cho, Yonjoo; Kim, Hyung-Sook
2014-01-01
As the number of organizations implementing action learning increases, both successful and failed cases also increase in action learning practice in South Korea. Existing studies on action learning have listed key success factors of action learning at the program level or at the team level but have not paid sufficient attention to the program…
Free space in the processes of action research
DEFF Research Database (Denmark)
Bladt, Mette; Nielsen, Kurt Aagaard
2013-01-01
In Scandinavia there exists an action research tradition called critical utopian action research (CUAR). Within CUAR, criticism and utopia is a core activity in the methods used and in the research as such. The utopian concept in this tradition should be understood as a productive concept, and thus...... not as eyebrow-lifting fantasy. Utopian horizons are, in light of critical reflection, formulated and developed. They act as Horizons indicating the direction of the work. The point of utopian notions – dreams and visions – is that they go beyond ‘the existing’ and become a way of working that allows us to think...... in concrete alternatives; in ‘different futures’. It allows us to ask the question: how do we wish to live? The rationale for the work of utopia must be found in CUAR’s connection to critical theory. From there, a perception that the world could be different is collected. It is only by utopian thinking...
Action potential initiation in the hodgkin-huxley model.
Directory of Open Access Journals (Sweden)
Lucy J Colwell
2009-01-01
Full Text Available A recent paper of B. Naundorf et al. described an intriguing negative correlation between variability of the onset potential at which an action potential occurs (the onset span and the rapidity of action potential initiation (the onset rapidity. This correlation was demonstrated in numerical simulations of the Hodgkin-Huxley model. Due to this antagonism, it is argued that Hodgkin-Huxley-type models are unable to explain action potential initiation observed in cortical neurons in vivo or in vitro. Here we apply a method from theoretical physics to derive an analytical characterization of this problem. We analytically compute the probability distribution of onset potentials and analytically derive the inverse relationship between onset span and onset rapidity. We find that the relationship between onset span and onset rapidity depends on the level of synaptic background activity. Hence we are able to elucidate the regions of parameter space for which the Hodgkin-Huxley model is able to accurately describe the behavior of this system.
My Life with State Space Models
DEFF Research Database (Denmark)
Lundbye-Christensen, Søren
2007-01-01
. The conceptual idea behind the state space model is that the evolution over time in the object we are observing and the measurement process itself are modelled separately. My very first serious analysis of a data set was done using a state space model, and since then I seem to have been "haunted" by state space...
Action-angle variables for geodesic motions in Sasaki-Einstein spaces Y
Visinescu, Mihai
2017-01-01
We use action-angle variables to describe the geodesic motions in the 5-dimensional Sasaki-Einstein spaces Y. This formulation allows us to study thoroughly the complete integrability of the system. We find that the Hamiltonian involves a reduced number of action variables. Therefore one of the fundamental frequencies is zero, indicating chaotic behavior when the system is perturbed.
Path-integral action of a particle in the noncommutative phase-space
Gangopadhyay, Sunandan
2016-01-01
In this paper we construct a path integral formulation of quantum mechanics on noncommutative phase-space. We first map the system to an equivalent system on the noncommutative plane. Then by applying the formalism of representing a quantum system in the space of Hilbert-Schmidt operators acting on noncommutative configuration space, the path integral action of a particle is derived. It is observed that the action has a similar form to that of a particle in a magnetic field in the noncommutative plane. From this action the energy spectrum is obtained for the free particle and the harmonic oscillator potential. We also show that the nonlocal nature (in time) of the action yields a second class constrained system from which the noncommutative Heisenberg algebra can be recovered.
Transplantation of Local Nets and Geometric Modular Action on Robertson-Walker Space-Times
Buchholz, D; Summers, S J; Buchholz, Detlev; Mund, Jens; Summers, Stephen J.
2001-01-01
A novel method of transplanting algebras of observables from de Sitter space to a large class of Robertson-Walker space-times is exhibited. It allows one to establish the existence of an abundance of local nets on these spaces which comply with a recently proposed condition of geometric modular action. The corresponding modular symmetry groups appearing in these examples also satisfy a condition of modular stability, which has been suggested as a substitute for the requirement of positivity of the energy in Minkowski space. Moreover, they exemplify the conjecture that the modular symmetry groups are generically larger than the isometry and conformal groups of the underlying space-times.
Schild Action and Space-Time Uncertainty Principle in String Theory
Yoneya, Tamiaki
1997-01-01
We show that the path-integral quantization of relativistic strings with the Schild action is essentially equivalent to the usual Polyakov quantization at critical space-time dimensions. We then present an interpretation of the Schild action which points towards a derivation of superstring theory as a theory of quantized space-time where the squared string scale plays the role of the minimum quantum for space-time areas. A tentative approach towards such a goal is proposed, based on a microca...
Lagrangian formulation of symmetric space sine-Gordon models
Bakas, Ioannis; Shin, H J; Park, Q Han
1996-01-01
The symmetric space sine-Gordon models arise by conformal reduction of ordinary 2-dim \\sigma-models, and they are integrable exhibiting a black-hole type metric in target space. We provide a Lagrangian formulation of these systems by considering a triplet of Lie groups F \\supset G \\supset H. We show that for every symmetric space F/G, the generalized sine-Gordon models can be derived from the G/H WZW action, plus a potential term that is algebraically specified. Thus, the symmetric space sine-Gordon models describe certain integrable perturbations of coset conformal field theories at the classical level. We also briefly discuss their vacuum structure, Backlund transformations, and soliton solutions.
Dynamic models in space and time
Elhorst, J.P.
2001-01-01
This paper presents a first-order autoregressive distributed lag model in both space and time. It is shown that this model encompasses a wide series of simpler models frequently used in the analysis of space-time data as well as models that better fit the data and have never been used before. A fram
Assessment of the NASA Space Shuttle Program's Problem Reporting and Corrective Action System
Korsmeryer, D. J.; Schreiner, J. A.; Norvig, Peter (Technical Monitor)
2001-01-01
This paper documents the general findings and recommendations of the Design for Safety Programs Study of the Space Shuttle Programs (SSP) Problem Reporting and Corrective Action (PRACA) System. The goals of this Study were: to evaluate and quantify the technical aspects of the SSP's PRACA systems, and to recommend enhancements addressing specific deficiencies in preparation for future system upgrades. The Study determined that the extant SSP PRACA systems accomplished a project level support capability through the use of a large pool of domain experts and a variety of distributed formal and informal database systems. This operational model is vulnerable to staff turnover and loss of the vast corporate knowledge that is not currently being captured by the PRACA system. A need for a Program-level PRACA system providing improved insight, unification, knowledge capture, and collaborative tools was defined in this study.
5-Dimensional Extended Space Model
Tsipenyuk, D. Yu.; Andreev, V. A.
2006-01-01
We put forward an idea that physical phenomena have to be treated in 5-dimensional space where the fifth coordinate is the interval S. Thus, we considered the (1+4) extended space G(T;X,Y,Z,S). In addition to Lorentz transformations (T;X), (T;Y), (T;Z) which are in (1+3)-dimensional Minkowski space, in the proposed (1+4)d extended space two other types of transformations exist in planes (T,S); (X,S), (Y,S), (Z,S) that converts massive particles into massless and vice versa. We also consider e...
Directory of Open Access Journals (Sweden)
Giovanni ePezzulo
2013-11-01
Full Text Available The article explores the possibilities of formalizing and explaining the mechanisms that support spatial and social perspective alignment sustained over the duration of a social interaction. The basic proposed principle is that in social contexts the mechanisms for sensorimotor transformations and multisensory integration (learn to incorporate information relative to the other actor(s, similar to the "re-calibration" of visual receptive fields in response to repeated tool use. This process aligns or merges the co-actors' spatial representations and creates a "Shared Action Space" supporting key computations of social interactions and joint actions; for example, the remapping between the coordinate systems and frames of reference of the co-actors, including perspective taking, the sensorimotor transformations required for lifting jointly an object, and the predictions of the sensory effects of such joint action. The social re-calibration is proposed to be based on common basis function maps and could constitute an optimal solution to sensorimotor transformation and multisensory integration in joint action or more in general social interaction contexts. However, certain situations such as discrepant postural and viewpoint alignment and associated differences in perspectives between the co-actors could constrain the process quite differently. We discuss how alignment is achieved in the first place, and how it is maintained over time, providing a taxonomy of various forms and mechanisms of space alignment and overlap based, for instance, on automaticity vs. control of the transformations between the two agents. Finally, we discuss the link between low-level mechanisms for the sharing of space and high-level mechanisms for the sharing of cognitive representations.
Bonini, Luca; Maranesi, Monica; Livi, Alessandro; Fogassi, Leonardo; Rizzolatti, Giacomo
2014-03-12
The macaque ventral premotor area F5 hosts two types of visuomotor grasping neurons: "canonical" neurons, which respond to visually presented objects and underlie visuomotor transformation for grasping, and "mirror" neurons, which respond during the observation of others' action, likely playing a role in action understanding. Some previous evidence suggested that canonical and mirror neurons could be anatomically segregated in different sectors of area F5. Here we investigated the functional properties of single neurons in the hand field of area F5 using various tasks similar to those originally designed to investigate visual responses to objects and actions. By using linear multielectrode probes, we were able to simultaneously record different types of neurons and to precisely localize their cortical depth. We recorded 464 neurons, of which 243 showed visuomotor properties. Canonical and mirror neurons were often present in the same cortical sites; and, most interestingly, a set of neurons showed both canonical and mirror properties, discharging to object presentation as well as during the observation of experimenter's goal-directed acts (canonical-mirror neurons). Typically, visual responses to objects were constrained to the monkey peripersonal space, whereas action observation responses were less space-selective. Control experiments showed that space-constrained coding of objects mostly relies on an operational (action possibility) rather than metric (absolute distance) reference frame. Interestingly, canonical-mirror neurons appear to code object as target for both one's own and other's action, suggesting that they could play a role in predictive representation of others' impending actions.
Simplicial models of trace spaces
DEFF Research Database (Denmark)
Raussen, Martin
2010-01-01
Directed algebraic topology studies topological spaces in which certain directed paths (d-paths) are singled out; in most cases of interest, the reverse path of a d-path is no longer a d-path. We are mainly concerned with spaces of directed paths between given end points, and how those vary under...
Mean Shift Detection for State Space Models
Kuhn, J.; Mandjes, M.; Taimre, T.; Weber, T.; McPhee, M.J.; Anderssen, R.S.
2015-01-01
In this paper we develop and validate a procedure for testing against a shift in mean in the observations and hidden state sequence of state space models with Gaussian noise. State space models are popular for modelling stochastic networks as they allow to take into account that observations of the
A Hybrid 3D Indoor Space Model
Jamali, Ali; Rahman, Alias Abdul; Boguslawski, Pawel
2016-10-01
GIS integrates spatial information and spatial analysis. An important example of such integration is for emergency response which requires route planning inside and outside of a building. Route planning requires detailed information related to indoor and outdoor environment. Indoor navigation network models including Geometric Network Model (GNM), Navigable Space Model, sub-division model and regular-grid model lack indoor data sources and abstraction methods. In this paper, a hybrid indoor space model is proposed. In the proposed method, 3D modeling of indoor navigation network is based on surveying control points and it is less dependent on the 3D geometrical building model. This research proposes a method of indoor space modeling for the buildings which do not have proper 2D/3D geometrical models or they lack semantic or topological information. The proposed hybrid model consists of topological, geometrical and semantical space.
A Hybrid 3D Indoor Space Model
Directory of Open Access Journals (Sweden)
A. Jamali
2016-10-01
Full Text Available GIS integrates spatial information and spatial analysis. An important example of such integration is for emergency response which requires route planning inside and outside of a building. Route planning requires detailed information related to indoor and outdoor environment. Indoor navigation network models including Geometric Network Model (GNM, Navigable Space Model, sub-division model and regular-grid model lack indoor data sources and abstraction methods. In this paper, a hybrid indoor space model is proposed. In the proposed method, 3D modeling of indoor navigation network is based on surveying control points and it is less dependent on the 3D geometrical building model. This research proposes a method of indoor space modeling for the buildings which do not have proper 2D/3D geometrical models or they lack semantic or topological information. The proposed hybrid model consists of topological, geometrical and semantical space.
Public space patterns: Modelling the language of urban space
Montenegro, N.; Beirao, J.N.; Duarte, J.P.
2011-01-01
This paper describes the “Public Space Patterns” ontology including its related rule-based model, used as a basic structure of a “City Information Modelling” (CIM). This model was developed within a larger research project aimed at developing a tool for urban planning and design. The main purpose is
An Evolution Model of Space Debris Environment
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Various types of models including engineering models andevolution models have been developed to understand space debris environment since 1960s. Evolution model, consisting of a set of supporting models such as Launch Model, Breakup Model and Atmosphere Model, can reliably predicts the evolution of space debris environment. Of these supporting models, Breakup Model is employed to describe the distribution of debris and debris cloud during a explosion or collision case which is one of the main factors affecting the amount of total space debris. An analytical orbit debris environment model referred to as the “Particles-In-Boxes" model has been introduced. By regarding the orbit debris as the freedom particles running in the huge volume, the sources and sinks mechanism is established. Then the PIB model is expanded to the case of multiple-species in multiple-tier system. Combined with breakup model, the evolution of orbit debris environment is predicted.
Spatial and frequency domain ring source models for the single muscle fiber action potential
DEFF Research Database (Denmark)
Henneberg, Kaj-åge; R., Plonsey
1994-01-01
In the paper, single-fibre models for the extracellular action potential are developed that will allow the potential to the evaluated at an arbitrary field point in the extracellular space. Fourier-domain models are restricted in that they evaluate potentials at equidistant points along a line...
Action-angle variables for geodesic motions in Sasaki-Einstein spaces $Y^{p,q}$
Visinescu, Mihai
2016-01-01
We use the action-angle variables to describe the geodesic motions in the $5$-dimensional Sasaki-Einstein spaces $Y^{p,q}$. This formulation allows us to study thoroughly the complete integrability of the system. We find that the Hamiltonian involves a reduced number of action variables. Therefore one of the fundamental frequency is zero indicating a chaotic behavior when the system is perturbed.
Model-theoretical foundation of action and progression
Institute of Scientific and Technical Information of China (English)
田启家; 史忠植
1997-01-01
Action is one of the most important concepts in computer science, and situation calculus is the standard formalism for representing and reasoning about actions and their effects. Situation calculus essentially could be presented in a logic framework. Based on the framework LR, such a logic framework is given. Minimal action theory is proposed and studied from the point of view of model theory. By theorems of mathematical logic, some results about the definability about the progression in minimal action theory are obtained.
Measurement Models for Reasoned Action Theory
Hennessy, Michael; Bleakley, Amy; FISHBEIN, MARTIN
2012-01-01
Quantitative researchers distinguish between causal and effect indicators. What are the analytic problems when both types of measures are present in a quantitative reasoned action analysis? To answer this question, we use data from a longitudinal study to estimate the association between two constructs central to reasoned action theory: behavioral beliefs and attitudes toward the behavior. The belief items are causal indicators that define a latent variable index while the attitude items are ...
Defining Learning Space in a Serious Game in Terms of Operative and Resultant Actions
Martin, Michael W.; Shen, Yuzhong
2012-01-01
This paper explores the distinction between operative and resultant actions in games, and proposes that the learning space created by a serious game is a function of these actions. Further, it suggests a possible relationship between these actions and the forms of cognitive load imposed upon the game player. Association of specific types of cognitive load with respective forms of actions in game mechanics also presents some heuristics for integrating learning content into serious games. Research indicates that different balances of these types of actions are more suitable for novice or experienced learners. By examining these relationships, we can develop a few basic principles of game design which have an increased potential to promote positive learning outcomes.
On the Cohomology of Orbit Space of Free $\\mathbb{Z}_p$-Actions on Lens Spaces
Indian Academy of Sciences (India)
Hemant Kumar Singh; Tej Bahadur Singh
2007-08-01
Let $G=\\mathbb{Z}_p, p$ an odd prime, act freely on a finite-dimensional -complex with $\\mathrm{mod} p$ cohomology isomorphic to that of a lens space $L^{2m-1}(p;q_1,\\ldots,q_m)$. In this paper, we determine the $\\mathrm{mod} p$ cohomology ring of the orbit space $X/G$, when $p^2\
Effective action and semiclassical limit of spin foam models
Mikovic, A
2011-01-01
We define an effective action for spin foam models of quantum gravity by adapting the background field method from quantum field theory. We show that the Regge action is the leading term in the semi-classical expansion of the spin foam effective action if the vertex amplitude has the large-spin asymptotics which is proportional to an exponential function of the vertex Regge action. In the case of the known three-dimensional and four-dimensional spin foam models this amounts to modifying the vertex amplitude such that the exponential asymptotics is obtained. In particular, we show that the ELPR/FK model vertex amplitude can be modified such that the new model is finite and has the Einstein-Hilbert action as its classical limit. We also calculate the first-order and some of the second-order quantum corrections in the semi-classical expansion of the effective action.
Measurement Models for Reasoned Action Theory.
Hennessy, Michael; Bleakley, Amy; Fishbein, Martin
2012-03-01
Quantitative researchers distinguish between causal and effect indicators. What are the analytic problems when both types of measures are present in a quantitative reasoned action analysis? To answer this question, we use data from a longitudinal study to estimate the association between two constructs central to reasoned action theory: behavioral beliefs and attitudes toward the behavior. The belief items are causal indicators that define a latent variable index while the attitude items are effect indicators that reflect the operation of a latent variable scale. We identify the issues when effect and causal indicators are present in a single analysis and conclude that both types of indicators can be incorporated in the analysis of data based on the reasoned action approach.
Level-0 action of $U_{q}(\\widehat{sl}_{n})$ on the q-deformed Fock spaces
Takemura, K; Takemura, Kouichi; Uglov, Denis
1996-01-01
On the level-1 Fock space modules of the algebra $U_q(\\hat{sl_n})$ we define a level-0 action $U_0$ of the $U_q(\\hat{sl_n})$, and an action of an abelian algebra of conserved Hamiltonians commuting with the $U_0$. An irreducible decomposition of the Fock space with respect to the level-0 action is derived by constructing a base of the Fock space in terms of the Non-symmetric Macdonald Polynomials.
Modelling social agents: Communication as actions
Dignum, F.P.M.; Linder, B. van; M. Wooldridge J. Muller and N. Jennings
1997-01-01
In this paper we present a formal framework for social agents. The social agents consist of four components: the information component (containing knowledge and belief), the action component, the motivational component (where goals, intentions, etc. play arole) and the social component (containing a
Space Vehicle Reliability Modeling in DIORAMA
Energy Technology Data Exchange (ETDEWEB)
Tornga, Shawn Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-07-12
When modeling system performance of space based detection systems it is important to consider spacecraft reliability. As space vehicles age the components become prone to failure for a variety of reasons such as radiation damage. Additionally, some vehicles may lose the ability to maneuver once they exhaust fuel supplies. Typically failure is divided into two categories: engineering mistakes and technology surprise. This document will report on a method of simulating space vehicle reliability in the DIORAMA framework.
Momentum-space Harper-Hofstadter model
Ozawa, Tomoki; Price, Hannah M.; Carusotto, Iacopo
2015-08-01
We show how the weakly trapped Harper-Hofstadter model can be mapped onto a Harper-Hofstadter model in momentum space. In this momentum-space model, the band dispersion plays the role of the periodic potential, the Berry curvature plays the role of an effective magnetic field, the real-space harmonic trap provides the momentum-space kinetic energy responsible for the hopping, and the trap position sets the boundary conditions around the magnetic Brillouin zone. Spatially local interactions translate into nonlocal interactions in momentum space: within a mean-field approximation, we show that increasing interparticle interactions leads to a structural change of the ground state, from a single rotationally symmetric ground state to degenerate ground states that spontaneously break rotational symmetry.
3D space analysis of dental models
Chuah, Joon H.; Ong, Sim Heng; Kondo, Toshiaki; Foong, Kelvin W. C.; Yong, Than F.
2001-05-01
Space analysis is an important procedure by orthodontists to determine the amount of space available and required for teeth alignment during treatment planning. Traditional manual methods of space analysis are tedious and often inaccurate. Computer-based space analysis methods that work on 2D images have been reported. However, as the space problems in the dental arch exist in all three planes of space, a full 3D analysis of the problems is necessary. This paper describes a visualization and measurement system that analyses 3D images of dental plaster models. Algorithms were developed to determine dental arches. The system is able to record the depths of the Curve of Spee, and quantify space liabilities arising from a non-planar Curve of Spee, malalignment and overjet. Furthermore, the difference between total arch space available and the space required to arrange the teeth in ideal occlusion can be accurately computed. The system for 3D space analysis of the dental arch is an accurate, comprehensive, rapid and repeatable method of space analysis to facilitate proper orthodontic diagnosis and treatment planning.
NASA Education and Educational Technologies Exemplified by the Space Weather Action Center Program
Reis, Norma Teresinha Oliveira; André, Claudio; Cline, Troy D.; Eastman, Timothy E.; Maher, Margaret J.; Mayo, Louis A.; Lewis, Elaine M.
We explore here the Space Weather Action Center (SWAC) Program, as an example of NASA initiatives in education. Many human activities in space can be disrupted by space weather. The main objective of this program is to enable students to produce space weather forecasts by accessing current NASA data. Implementation of the SWAC Program requires: technological resources, online materials, and systematic work. Instructional guides, materials and methods are explained on the Space Weather Action Center Web site (http://sunearthday.nasa.gov/swac). Ultimately, students’ forecasts can be presented through a variety of accessible media including inexpensive video editing software and/or already existing school-based broadcast studios. This cross-curricular program is targeted to middle and high school and can be applied in almost all educational contexts as the number of schools with computer and internet access increases worldwide. SWAC is a pioneer initiative that contributes to fostering student interest in STEM and promotes their intellectual autonomy. Through SWAC, they get to act like real scientists by accessing, analyzing, recording, and communicating space weather forecasts in a professional approach.
The Cohomology of Orbit Spaces of Certain Free Circle Group Actions
Indian Academy of Sciences (India)
Hemant Kumar Singh; Tej Bahadur Singh
2012-02-01
Suppose that $G=\\mathbb{S}^1$ acts freely on a finitistic space whose (mod ) cohomology ring is isomorphic to that of a lens space $L^{2m-1}(p;q_1,\\ldots,q_m)$ or $\\mathbb{S}^1×\\mathbb{C}P^{m-1}$. The mod index of the action is defined to be the largest integer such that $^n≠ 0$, where $\\in H^2(X/G;\\mathbb{Z}_p)$ is the nonzero characteristic class of the $\\mathbb{S}^1$-bundle $\\mathbb{S}^1\\hookrightarrow X→ X/G$. We show that the mod index of a free action of on $\\mathbb{S}^1×\\mathbb{C}P^{m-1}$ is -1, when it is defined. Using this, we obtain a Borsuk–Ulam type theorem for a free -action on $\\mathbb{S}^1×\\mathbb{C}P^{m-1}$. It is note worthy that the mod index for free -actions on the cohomology lens space is not defined.
Modeling the value of strategic actions in the superior colliculus
Directory of Open Access Journals (Sweden)
Dhushan Thevarajah
2010-02-01
Full Text Available In learning models of strategic game play, an agent constructs a valuation (action value over possible future choices as a function of past actions and rewards. Choices are then stochastic functions of these action values. Our goal is to uncover a neural signal that correlates with the action value posited by behavioral learning models. We measured activity from neurons in the superior colliculus (SC, a midbrain region involved in planning saccadic eye movements, in monkeys while they performed two saccade tasks. In the strategic task, monkeys competed against a computer in a saccade version of the mixed-strategy game “matching-pennies”. In the instructed task, stochastic saccades were elicited through explicit instruction rather than free choices. In both tasks, neuronal activity and behavior were shaped by past actions and rewards with more recent events exerting a larger influence. Further, SC activity predicted upcoming choices during the strategic task and upcoming reaction times during the instructed task. Finally, we found that neuronal activity in both tasks correlated with an established learning model, the Experience Weighted Attraction model of action valuation (Ho, Camerer, and Chong, 2007. Collectively, our results provide evidence that action values hypothesized by learning models are represented in the motor planning regions of the brain in a manner that could be used to select strategic actions.
Lag space estimation in time series modelling
DEFF Research Database (Denmark)
Goutte, Cyril
1997-01-01
The purpose of this article is to investigate some techniques for finding the relevant lag-space, i.e. input information, for time series modelling. This is an important aspect of time series modelling, as it conditions the design of the model through the regressor vector a.k.a. the input layer...
Improved actions for the two-dimensional sigma-model
Caracciolo, Sergio; Montanari, Andrea; Pelissetto, Andrea
1997-01-01
For the O(N) sigma-model we studied the improvement program for actions with two- and four-spin interactions. An interesting example is an action which is reflection-positive, on-shell improved, and has all the coupling defined on an elementary plaquette. We show the large N solution and preliminary Monte Carlo results for N=3.
Effective action for EPRL/FK spin foam models
Mikovic, Aleksandar
2011-01-01
We show that a natural modification of the EPRL/FK vertex amplitude gives a finite spin foam model whose effective action gives the Einstein-Hilbert action in the limit of large spins and arbitrarily fine spacetime triangulations. The first-order quantum corrections can be easily computed and we show how to calculate the higher-order corrections.
Outdoor-indoor Space: Unified Modeling and Shortest Path Search
DEFF Research Database (Denmark)
Jensen, Søren Kejser; Nielsen, Jens Thomas Vejlby; Lu, Hua;
2016-01-01
Graph models are widely used for representing the topology of outdoor space (O-Space) and indoor space (I-Space). However, existing models neglect the intersection between O-Space and I-Space, only allowing for computations such as shortest path and nearest neighbor queries in either O-Space or I...
The State Space Models Toolbox for MATLAB
Directory of Open Access Journals (Sweden)
Jyh-Ying Peng
2011-05-01
Full Text Available State Space Models (SSM is a MATLAB toolbox for time series analysis by state space methods. The software features fully interactive construction and combination of models, with support for univariate and multivariate models, complex time-varying (dy- namic models, non-Gaussian models, and various standard models such as ARIMA and structural time-series models. The software includes standard functions for Kalman fil- tering and smoothing, simulation smoothing, likelihood evaluation, parameter estimation, signal extraction and forecasting, with incorporation of exact initialization for filters and smoothers, and support for missing observations and multiple time series input with com- mon analysis structure. The software also includes implementations of TRAMO model selection and Hillmer-Tiao decomposition for ARIMA models. The software will provide a general toolbox for time series analysis on the MATLAB platform, allowing users to take advantage of its readily available graph plotting and general matrix computation capabilities.
Observational modeling of topological spaces
Energy Technology Data Exchange (ETDEWEB)
Molaei, M.R. [Department of Mathematics, Shahid Bahonar University of Kerman, Kerman 76169-14111 (Iran, Islamic Republic of)], E-mail: mrmolaei@mail.uk.ac.ir
2009-10-15
In this paper a model for a multi-dimensional observer by using of the fuzzy theory is presented. Relative form of Tychonoff theorem is proved. The notion of topological entropy is extended. The persistence of relative topological entropy under relative conjugate relation is proved.
A continuous-time neural model for sequential action.
Kachergis, George; Wyatte, Dean; O'Reilly, Randall C; de Kleijn, Roy; Hommel, Bernhard
2014-11-01
Action selection, planning and execution are continuous processes that evolve over time, responding to perceptual feedback as well as evolving top-down constraints. Existing models of routine sequential action (e.g. coffee- or pancake-making) generally fall into one of two classes: hierarchical models that include hand-built task representations, or heterarchical models that must learn to represent hierarchy via temporal context, but thus far lack goal-orientedness. We present a biologically motivated model of the latter class that, because it is situated in the Leabra neural architecture, affords an opportunity to include both unsupervised and goal-directed learning mechanisms. Moreover, we embed this neurocomputational model in the theoretical framework of the theory of event coding (TEC), which posits that actions and perceptions share a common representation with bidirectional associations between the two. Thus, in this view, not only does perception select actions (along with task context), but actions are also used to generate perceptions (i.e. intended effects). We propose a neural model that implements TEC to carry out sequential action control in hierarchically structured tasks such as coffee-making. Unlike traditional feedforward discrete-time neural network models, which use static percepts to generate static outputs, our biological model accepts continuous-time inputs and likewise generates non-stationary outputs, making short-timescale dynamic predictions.
AX-5 space suit reliability model
Reinhardt, AL; Magistad, John
1990-01-01
The AX-5 is an all metal Extra-vehicular (EVA) space suit currently under consideration for use on Space Station Freedom. A reliability model was developed based on the suit's unique design and on projected joint cycle requirements. Three AX-5 space suit component joints were cycled under simulated load conditions in accordance with NASA's advanced space suit evaluation plan. This paper will describe the reliability model developed, the results of the cycle testing, and an interpretation of the model and test results in terms of projected Mean Time Between Failure for the AX-5. A discussion of the maintenance implications and life cycle for the AX-5 based on this projection is also included.
An introduction to Space Weather Integrated Modeling
Zhong, D.; Feng, X.
2012-12-01
The need for a software toolkit that integrates space weather models and data is one of many challenges we are facing with when applying the models to space weather forecasting. To meet this challenge, we have developed Space Weather Integrated Modeling (SWIM) that is capable of analysis and visualizations of the results from a diverse set of space weather models. SWIM has a modular design and is written in Python, by using NumPy, matplotlib, and the Visualization ToolKit (VTK). SWIM provides data management module to read a variety of spacecraft data products and a specific data format of Solar-Interplanetary Conservation Element/Solution Element MHD model (SIP-CESE MHD model) for the study of solar-terrestrial phenomena. Data analysis, visualization and graphic user interface modules are also presented in a user-friendly way to run the integrated models and visualize the 2-D and 3-D data sets interactively. With these tools we can locally or remotely analysis the model result rapidly, such as extraction of data on specific location in time-sequence data sets, plotting interplanetary magnetic field lines, multi-slicing of solar wind speed, volume rendering of solar wind density, animation of time-sequence data sets, comparing between model result and observational data. To speed-up the analysis, an in-situ visualization interface is used to support visualizing the data 'on-the-fly'. We also modified some critical time-consuming analysis and visualization methods with the aid of GPU and multi-core CPU. We have used this tool to visualize the data of SIP-CESE MHD model in real time, and integrated the Database Model of shock arrival, Shock Propagation Model, Dst forecasting model and SIP-CESE MHD model developed by SIGMA Weather Group at State Key Laboratory of Space Weather/CAS.
The STAMP Software for State Space Models
Directory of Open Access Journals (Sweden)
Roy Mendelssohn
2011-05-01
Full Text Available This paper reviews the use of STAMP (Structural Time Series Analyser, Modeler and Predictor for modeling time series data using state-space methods with unobserved components. STAMP is a commercial, GUI-based program that runs on Windows, Linux and Macintosh computers as part of the larger OxMetrics System. STAMP can estimate a wide-variety of both univariate and multivariate state-space models, provides a wide array of diagnostics, and has a batch mode capability. The use of STAMP is illustrated for the Nile river data which is analyzed throughout this issue, as well as by modeling a variety of oceanographic and climate related data sets. The analyses of the oceanographic and climate data illustrate the breadth of models available in STAMP, and that state-space methods produce results that provide new insights into important scientific problems.
Preliminary Multivariable Cost Model for Space Telescopes
Stahl, H. Philip
2010-01-01
Parametric cost models are routinely used to plan missions, compare concepts and justify technology investments. Previously, the authors published two single variable cost models based on 19 flight missions. The current paper presents the development of a multi-variable space telescopes cost model. The validity of previously published models are tested. Cost estimating relationships which are and are not significant cost drivers are identified. And, interrelationships between variables are explored
Directory of Open Access Journals (Sweden)
Abdeldjallil eNaceri
2015-09-01
Full Text Available In our daily life experience, the angular size of an object correlates with its distance from the observer, provided that the physical size of the object remains constant. In this work, we investigated depth perception in action space (i.e., beyond the arm reach, while keeping the angular size of the target object constant. This was achieved by increasing the physical size of the target object as its distance to the observer increased. To the best of our knowledge, this is the first time that a similar protocol has been tested in action space, for distances to the observer ranging from 1.4 to 2.4m. We replicated the task in virtual and real environments and we found that the performance was significantly different between the two environments. In the real environment, all participants perceived the depth of the target object precisely. Whereas, in virtual reality the responses were significantly less precise, although, still above chance level in 16 of the 20 observers. The difference in the discriminability of the stimuli was likely due to different contributions of the convergence and the accommodation cues in the two environments. The values of Weber fractions estimated in our study were compared to those reported in previous studies in peripersonal and action space.
Naceri, Abdeldjallil; Moscatelli, Alessandro; Chellali, Ryad
2015-01-01
In our daily life experience, the angular size of an object correlates with its distance from the observer, provided that the physical size of the object remains constant. In this work, we investigated depth perception in action space (i.e., beyond the arm reach), while keeping the angular size of the target object constant. This was achieved by increasing the physical size of the target object as its distance to the observer increased. To the best of our knowledge, this is the first time that a similar protocol has been tested in action space, for distances to the observer ranging from 1.4–2.4 m. We replicated the task in virtual and real environments and we found that the performance was significantly different between the two environments. In the real environment, all participants perceived the depth of the target object precisely. Whereas, in virtual reality (VR) the responses were significantly less precise, although, still above chance level in 16 of the 20 observers. The difference in the discriminability of the stimuli was likely due to different contributions of the convergence and the accommodation cues in the two environments. The values of Weber fractions estimated in our study were compared to those reported in previous studies in peripersonal and action space. PMID:26441608
Rejoinder: Sifting through model space
Heisey, Dennis M.; Osnas, Erik E.; Cross, Paul C.; Joly, Damien O.; Langenberg, Julia A.; Miller, Michael W.
2010-01-01
Observational data sets generated by complex processes are common in ecology. Traditionally these have been very challenging to analyze because of the limitations of available statistical tools. This seems to be changing, and these are exciting times to be involved with ecological statistics, not just because of the neo-Bayesian revival but also because of the proliferation of computationally intensive methods in general. It is now possible to fit much richer models to observational data than in the relatively recent past, which in turn has stimulated much interest in how to evaluate and compare such models. In such an immature, vibrant, and rapidly growing field, not everyone is going to agree on the best way to do things. This is reflected in the contrast of opinions offered by the discussants. Each offers a thoughtful and thought-provoking critique of our work that reflects the current thinking in a non-negligible segment of the ecological data analysis community. We want to thank them for their insights.
Developing Viable Financing Models for Space Tourism
Eilingsfeld, F.; Schaetzler, D.
2002-01-01
Increasing commercialization of space services and the impending release of government's control of space access promise to make space ventures more attractive. Still, many investors shy away from going into the space tourism market as long as they do not feel secure that their return expectations will be met. First and foremost, attracting investors from the capital markets requires qualifying financing models. Based on earlier research on the cost of capital for space tourism, this paper gives a brief run-through of commercial, technical and financial due diligence aspects. After that, a closer look is taken at different valuation techniques as well as alternative ways of streamlining financials. Experience from earlier ventures has shown that the high cost of capital represents a significant challenge. Thus, the sophistication and professionalism of business plans and financial models needs to be very high. Special emphasis is given to the optimization of the debt-to-equity ratio over time. The different roles of equity and debt over a venture's life cycle are explained. Based on the latter, guidelines for the design of an optimized loan structure are given. These are then applied to simulating the financial performance of a typical space tourism venture over time, including the calculation of Weighted Average Cost of Capital (WACC) and Net Present Value (NPV). Based on a concluding sensitivity analysis, the lessons learned are presented. If applied properly, these will help to make space tourism economically viable.
Quadratic adaptive algorithm for solving cardiac action potential models.
Chen, Min-Hung; Chen, Po-Yuan; Luo, Ching-Hsing
2016-10-01
An adaptive integration method is proposed for computing cardiac action potential models accurately and efficiently. Time steps are adaptively chosen by solving a quadratic formula involving the first and second derivatives of the membrane action potential. To improve the numerical accuracy, we devise an extremum-locator (el) function to predict the local extremum when approaching the peak amplitude of the action potential. In addition, the time step restriction (tsr) technique is designed to limit the increase in time steps, and thus prevent the membrane potential from changing abruptly. The performance of the proposed method is tested using the Luo-Rudy phase 1 (LR1), dynamic (LR2), and human O'Hara-Rudy dynamic (ORd) ventricular action potential models, and the Courtemanche atrial model incorporating a Markov sodium channel model. Numerical experiments demonstrate that the action potential generated using the proposed method is more accurate than that using the traditional Hybrid method, especially near the peak region. The traditional Hybrid method may choose large time steps near to the peak region, and sometimes causes the action potential to become distorted. In contrast, the proposed new method chooses very fine time steps in the peak region, but large time steps in the smooth region, and the profiles are smoother and closer to the reference solution. In the test on the stiff Markov ionic channel model, the Hybrid blows up if the allowable time step is set to be greater than 0.1ms. In contrast, our method can adjust the time step size automatically, and is stable. Overall, the proposed method is more accurate than and as efficient as the traditional Hybrid method, especially for the human ORd model. The proposed method shows improvement for action potentials with a non-smooth morphology, and it needs further investigation to determine whether the method is helpful during propagation of the action potential. Copyright © 2016 Elsevier Ltd. All rights
Personalised modelling of facial action unit intensity
Yang, Shuang; Rudovic, Ognjen; Pavlovic, Vladimir; Pantic, Maja
2014-01-01
Facial expressions depend greatly on facial morphology and expressiveness of the observed person. Recent studies have shown great improvement of the personalized over non-personalized models in variety of facial expression related tasks, such as face and emotion recognition. However, in the context
Backward Causation in Complex Action Model --- Superdeterminism and Transactional Interpretations
Nielsen, Holger B
2010-01-01
It is shown that the transactional interpretation of quantum mechanics being referred back to Feynman-Wheeler's time reversal symmetric radiation theory has reminiscences to our complex action model. In this complex action model the initial conditions are in principle even calculable. Thus it philosophically points towards superdeterminism, but really the Bell theorem problem is solved in our model of complex action by removing the significance of signals running slower than by light velocity. Our model as earlier published predicts that LHC should have some failure before reaching to have produced as many Higgs-particles as would have been produced the SSC accelerator. In the present article, we point out that a cardgame involving whether to restrict LHC-running as we have proposed to test our model will under all circumstances be a success.
Multimedia Mapping using Continuous State Space Models
DEFF Research Database (Denmark)
Lehn-Schiøler, Tue
2004-01-01
In this paper a system that transforms speech waveforms to animated faces are proposed. The system relies on continuous state space models to perform the mapping, this makes it possible to ensure video with no sudden jumps and allows continuous control of the parameters in 'face space'. Simulations...... are performed on recordings of 3-5 sec. video sequences with sentences from the Timit database. The model is able to construct an image sequence from an unknown noisy speech sequence fairly well even though the number of training examples are limited....
Gauge invariant actions for string models
Energy Technology Data Exchange (ETDEWEB)
Banks, T.
1986-06-01
String models of unified interactions are elegant sets of Feynman rules for the scattering of gravitons, gauge bosons, and a host of massive excitations. The purpose of these lectures is to describe the progress towards a nonperturbative formulation of the theory. Such a formulation should make the geometrical meaning of string theory manifest and explain the many ''miracles'' exhibited by the string Feynman rules. There are some new results on gauge invariant observables, on the cosmological constant, and on the symmetries of interacting string field theory. 49 refs.
The communicative action and information: a learning to learn transdisciplinary model
Directory of Open Access Journals (Sweden)
Márcia Marques
2015-09-01
Full Text Available This article is about the communicative action and information model for social networking in digital environments, a transdisciplinary articulation of knowledge and learning that guides the collective and collaborative construction of inclusive communication strategies and ongoing development of competencies to promote understanding between the players, members of a social network. Information Science, Communication itself and Information and Communication Technologies (ICT promote this articulation in transdisciplinary mode. This model is the basis for the diagnosis and action planning herein: for the collective construction of communication relationships negotiated between participants of the network; for the creation of digital environments that provide spaces for learning to cope with information and communication; so that public communication experts may promote transparency of information as stated in the Constitution and the Law on Access to Information in Brazil. The model articulates methodologies for analyses of the individual and the network (Users Study, Social Network Analysis, multivoicedness to obtain diagnosis and elaborate communication and information action planning.
A simplified model of collision-driven dynamo action in small bodies
Wei, Xing
2013-01-01
We investigate numerically the self-sustained dynamo action in a spinning sphere whose sense of rotation reverses periodically. This system serves as a simple model of a dynamo in small bodies powered by frequent collisions. It is found that dynamo action is possible in some intervals of collision rates. At high Ekman numbers the laminar spin-up flow is helical in the boundary layers and the Ekman circulation together with the azimuthal shear powers the dynamo action. At low Ekman number a non-axisymmetric instability helps the dynamo action. The intermittency of magnetic field occurs at low Ekman number. A lower bound of magnetic energy is numerically obtained, and the space-averaged field in the fluid core and the surface field of a small body are roughly estimated.
A computational model of perception and action for cognitive robotics.
Haazebroek, Pascal; van Dantzig, Saskia; Hommel, Bernhard
2011-11-01
Robots are increasingly expected to perform tasks in complex environments. To this end, engineers provide them with processing architectures that are based on models of human information processing. In contrast to traditional models, where information processing is typically set up in stages (i.e., from perception to cognition to action), it is increasingly acknowledged by psychologists and robot engineers that perception and action are parts of an interactive and integrated process. In this paper, we present HiTEC, a novel computational (cognitive) model that allows for direct interaction between perception and action as well as for cognitive control, demonstrated by task-related attentional influences. Simulation results show that key behavioral studies can be readily replicated. Three processing aspects of HiTEC are stressed for their importance for cognitive robotics: (1) ideomotor learning of action control, (2) the influence of task context and attention on perception, action planning, and learning, and (3) the interaction between perception and action planning. Implications for the design of cognitive robotics are discussed.
Cosmological Models with Fractional Derivatives and Fractional Action Functional
Institute of Scientific and Technical Information of China (English)
V.K. Shchigolev
2011-01-01
Cosmological models of a scalar field with dynamical equations containing fractional derivatives or derived from the Einstein-Hilbert action of fractional order, are constructed. A number of exact solutions to those equations of fractional cosmological models in both eases is given.
Modelling Complex Relevance Spaces with Copulas
C. Eickhoff (Carsten); A.P. de Vries (Arjen)
2014-01-01
htmlabstractModern relevance models consider a wide range of criteria in order to identify those documents that are expected to satisfy the user's information need. With growing dimensionality of the underlying relevance spaces the need for sophisticated score combination and estimation schemes
Habitability Concept Models for Living in Space
Ferrino, M.
2002-01-01
As growing trends show, living in "space" has acquired new meanings, especially considering the utilization of the International Space Station (ISS) with regard to group interaction as well as individual needs in terms of time, space and crew accommodations. In fact, for the crew, the Spaced Station is a combined Laboratory-Office/Home and embodies ethical, social, and cultural aspects as additional parameters to be assessed to achieve a user centered architectural design of crew workspace. Habitability Concept Models can improve the methods and techniques used to support the interior design and layout of space architectures and at the same time guarantee a human focused approach. This paper discusses and illustrates some of the results obtained for the interior design of a Habitation Module for the ISS. In this work, two different but complementary approaches are followed. The first is "object oriented" and based on Video Data (American and Russian) supported by Proxemic methods (Edward T. Hall, 1963 and Francesca Pregnolato, 1998). This approach offers flexible and adaptive design solutions. The second is "subject oriented" and based on a Virtual Reality environment. With this approach human perception and cognitive aspects related to a specific crew task are considered. Data obtained from these two approaches are used to verify requirements and advance the design of the Habitation Module for aspects related to man machine interfaces (MMI), ergonomics, work and free-time. It is expected that the results achieved can be applied to future space related projects.
Concepts of disability: the Activity Space Model.
Kopec, J A
1995-03-01
This paper describes a new conceptual framework for functional assessment, the Activity Space Model (ASM). According to this model, functional impairments may lead to restrictions in an individual's activity space, a multidimensional space that represents human potential for activity. For each elementary ability, restrictions in the corresponding dimension of the activity space can be evaluated by deriving a difficulty curve that depicts the relationship between the level of performance and the psychophysical cost of activity. The effect of disease on daily functioning is explained in terms of a tradeoff between the psychophysical cost and the value of each act of behavior to the disabled individual. These two constructs are measured on the same scale and expressed in units of difficulty. The location of each task within the activity space in relation to the difficulty curve determines whether it will be performed or avoided at a given point in time. The ASM has both theoretical and practical implications. It offers a new, integrated perspective on disability and suggests new strategies for developing and evaluating functional assessment measures.
Topological Lattice Actions for the 2d XY Model
Bietenholz, W; Niedermayer, F; Pepe, M; Rejón-Barrera, F G; Wiese, U -J
2012-01-01
We consider the 2d XY Model with topological lattice actions, which are invariant against small deformations of the field configuration. These actions constrain the angle between neighbouring spins by an upper bound, or they explicitly suppress vortices (and anti-vortices). Although topological actions do not have a classical limit, they still lead to the universal behaviour of the Berezinskii-Kosterlitz-Thouless (BKT) phase transition - at least up to moderate vortex suppression. Thus our study underscores the robustness of universality, which persists even when basic principles of classical physics are violated. In the massive phase, the analytically known Step Scaling Function (SSF) is reproduced in numerical simulations. In the massless phase, the BKT value of the critical exponent eta_c is confirmed. Hence, even though for some topological actions vortices cost zero energy, they still drive the standard BKT transition. In addition we identify a vortex-free transition point, which deviates from the BKT be...
The Perception-Action Model: Counting Computational Mechanisms
DEFF Research Database (Denmark)
Grünbaum, Thor
2016-01-01
Milner and Goodale’s Two Visual Systems Hypothesis (TVSH) is regarded as common ground in recent discussions of visual consciousness. A central part of TVSH is a functional model of vision and action (a functional perception-action model, PAM for short). In this paper, I provide a brief overview...... of these current discussions and argue that PAM is ambiguous between a strong and a weak version. I argue that, given a standard way of individuating computational mechanisms, the available evidence cannot be used to distinguish between these versions. This not only has consequences for philosophical theories...
Approximate Methods for State-Space Models
Koyama, Shinsuke; Shalizi, Cosma Rohilla; Kass, Robert E; 10.1198/jasa.2009.tm08326
2010-01-01
State-space models provide an important body of techniques for analyzing time-series, but their use requires estimating unobserved states. The optimal estimate of the state is its conditional expectation given the observation histories, and computing this expectation is hard when there are nonlinearities. Existing filtering methods, including sequential Monte Carlo, tend to be either inaccurate or slow. In this paper, we study a nonlinear filter for nonlinear/non-Gaussian state-space models, which uses Laplace's method, an asymptotic series expansion, to approximate the state's conditional mean and variance, together with a Gaussian conditional distribution. This {\\em Laplace-Gaussian filter} (LGF) gives fast, recursive, deterministic state estimates, with an error which is set by the stochastic characteristics of the model and is, we show, stable over time. We illustrate the estimation ability of the LGF by applying it to the problem of neural decoding and compare it to sequential Monte Carlo both in simulat...
Modeling Space Radiation with Radiomimetic Agent Bleomycin
Lu, Tao
2017-01-01
Space radiation consists of proton and helium from solar particle events (SPE) and high energy heavy ions from galactic cosmic ray (GCR). This mixture of radiation with particles at different energy levels has different effects on biological systems. Currently, majority studies of radiation effects on human were based on single-source radiation due to the limitation of available method to model effects of space radiation on living organisms. While NASA Space Radiation Laboratory is working on advanced switches to make it possible to have a mixed field radiation with particles of different energies, the radiation source will be limited. Development of an easily available experimental model for studying effects of mixed field radiation could greatly speed up our progress in our understanding the molecular mechanisms of damage and responses from exposure to space radiation, and facilitate the discovery of protection and countermeasures against space radiation, which is critical for the mission to Mars. Bleomycin, a radiomimetic agent, has been widely used to study radiation induced DNA damage and cellular responses. Previously, bleomycin was often compared to low low Linear Energy Transfer (LET) gamma radiation without defined characteristics. Our recent work demonstrated that bleomycin could induce complex clustered DNA damage in human fibroblasts that is similar to DNA damage induced by high LET radiation. These type of DNA damage is difficult to repair and can be visualized by gamma-H2Ax staining weeks after the initial insult. The survival ratio between early and late plating of human fibroblasts after bleomycin treatment is between low LET and high LET radiation. Our results suggest that bleomycin induces DNA damage and other cellular stresses resembling those resulted from mixed field radiation with both low and high LET particles. We hypothesize that bleomycin could be used to mimic space radiation in biological systems. Potential advantages and limitations of
Indian Academy of Sciences (India)
Debashish Goswami
2015-02-01
Let be one of the classical compact, simple, centre-less, connected Lie groups of rank with a maximal torus , the Lie algebra $\\mathcal{G}$ and let $\\{E_{i},F_{i},H_{i},i=1,\\ldots,n\\}$ be tha standard set of generators corresponding to a basis of the root system. Consider the adjoint-orbit space $M=\\{\\text{Ad}_{g}(H_{1}), g\\in G\\}$, identified with the homogeneous space / where $L=\\{g\\in G : \\text{Ad}_{g}(H_{1})=H_{1}\\}$. We prove that the coordinate functions $f_{i}(g):=_{i}(\\text{Ad}_{g}(H_{1}))$, $i=1,\\ldots,n$, where $\\{_{1},\\ldots,_{n}\\}$ is basis of $\\mathcal{G}'$ are `quadratically independent' in the sense that they do not satisfy any nontrivial homogeneous quadratic relations among them. Using this, it is proved that there is no genuine compact quantum group which can act faithfully on $C(M)$ such that the action leaves invariant the linear span of the above coordinate functions. As a corollary, it is also shown that any compact quantum group having a faithful action on the noncommutative manifold obtained by Rieffel deformation of satisfying a similar `linearity' condition must be a Rieffel-Wang type deformation of some compact group.
O(N) Models with Topological Lattice Actions
Bietenholz, Wolfgang; Gerber, Urs; Niedermayer, Ferenc; Pepe, Michele; Rejón-Barrera, Fernando G; Wiese, Uwe-Jens
2013-01-01
A variety of lattice discretisations of continuum actions has been considered, usually requiring the correct classical continuum limit. Here we discuss "weird" lattice formulations without that property, namely lattice actions that are invariant under most continuous deformations of the field configuration, in one version even without any coupling constants. It turns out that universality is powerful enough to still provide the correct quantum continuum limit, despite the absence of a classical limit, or a perturbative expansion. We demonstrate this for a set of O(N) models (or non-linear $\\sigma$-models). Amazingly, such "weird" lattice actions are not only in the right universality class, but some of them even have practical benefits, in particular an excellent scaling behaviour.
Adaptive Numerical Algorithms in Space Weather Modeling
Toth, Gabor; vanderHolst, Bart; Sokolov, Igor V.; DeZeeuw, Darren; Gombosi, Tamas I.; Fang, Fang; Manchester, Ward B.; Meng, Xing; Nakib, Dalal; Powell, Kenneth G.; Stout, Quentin F.; Glocer, Alex; Ma, Ying-Juan; Opher, Merav
2010-01-01
Space weather describes the various processes in the Sun-Earth system that present danger to human health and technology. The goal of space weather forecasting is to provide an opportunity to mitigate these negative effects. Physics-based space weather modeling is characterized by disparate temporal and spatial scales as well as by different physics in different domains. A multi-physics system can be modeled by a software framework comprising of several components. Each component corresponds to a physics domain, and each component is represented by one or more numerical models. The publicly available Space Weather Modeling Framework (SWMF) can execute and couple together several components distributed over a parallel machine in a flexible and efficient manner. The framework also allows resolving disparate spatial and temporal scales with independent spatial and temporal discretizations in the various models. Several of the computationally most expensive domains of the framework are modeled by the Block-Adaptive Tree Solar wind Roe Upwind Scheme (BATS-R-US) code that can solve various forms of the magnetohydrodynamics (MHD) equations, including Hall, semi-relativistic, multi-species and multi-fluid MHD, anisotropic pressure, radiative transport and heat conduction. Modeling disparate scales within BATS-R-US is achieved by a block-adaptive mesh both in Cartesian and generalized coordinates. Most recently we have created a new core for BATS-R-US: the Block-Adaptive Tree Library (BATL) that provides a general toolkit for creating, load balancing and message passing in a 1, 2 or 3 dimensional block-adaptive grid. We describe the algorithms of BATL and demonstrate its efficiency and scaling properties for various problems. BATS-R-US uses several time-integration schemes to address multiple time-scales: explicit time stepping with fixed or local time steps, partially steady-state evolution, point-implicit, semi-implicit, explicit/implicit, and fully implicit numerical
Study on Strand Space Model Theory
Institute of Scientific and Technical Information of China (English)
JI QingGuang(季庆光); QING SiHan(卿斯汉); ZHOU YongBin(周永彬); FENG DengGuo(冯登国)
2003-01-01
The growing interest in the application of formal methods of cryptographic pro-tocol analysis has led to the development of a number of different ways for analyzing protocol. Inthis paper, it is strictly proved that if for any strand, there exists at least one bundle containingit, then an entity authentication protocol is secure in strand space model (SSM) with some smallextensions. Unfortunately, the results of attack scenario demonstrate that this protocol and the Yahalom protocol and its modification are de facto insecure. By analyzing the reasons of failure offormal inference in strand space model, some deficiencies in original SSM are pointed out. In orderto break through these limitations of analytic capability of SSM, the generalized strand space model(GSSM) induced by some protocol is proposed. In this model, some new classes of strands, oraclestrands, high order oracle strands etc., are developed, and some notions are formalized strictly in GSSM, such as protocol attacks, valid protocol run and successful protocol run. GSSM can thenbe used to further analyze the entity authentication protocol. This analysis sheds light on why thisprotocol would be vulnerable while it illustrates that GSSM not only can prove security protocolcorrect, but also can be efficiently used to construct protocol attacks. It is also pointed out thatusing other protocol to attack some given protocol is essentially the same as the case of using themost of protocol itself.
A biologically plausible embodied model of action discovery
Directory of Open Access Journals (Sweden)
Rufino eBolado-Gomez
2013-03-01
Full Text Available During development, animals can spontaneously discover action-outcomepairings enabling subsequent achievement of their goals. We present abiologically plausible embodied model addressing key aspects of thisprocess. The biomimetic model core comprises the basal ganglia and itsloops through cortex and thalamus. We incorporate reinforcementlearning with phasic dopamine supplying a sensory prediction error,signalling 'surprising' outcomes. Phasic dopamine is used in acorticostriatal learning rule which is consistent with recent data. Wealso hypothesised that objects associated with surprising outcomesacquire 'novelty salience' contingent on the predicability of theoutcome. To test this idea we used a simple model of predictiongoverning the dynamics of novelty salience and phasic dopamine. Thetask of the virtual robotic agent mimicked an in vivo counterpart(Gancarz et al., 2011 and involved interaction with a target objectwhich caused a light flash, or a control object which did not.Learning took place according to two schedules. In one, the phasicoutcome was delivered after interaction with the target in anunpredictable way which emulated the in vivo protocol. Without noveltysalience, the model was unable to account for the experimental data.In the other schedule, the phasic outcome was reliably delivered andthe agent showed a rapid increase in the number of interactions withthe target which then decreased over subsequent sessions. We arguethis is precisely the kind of change in behaviour required torepeatedly present representations of context, action and outcome, toneural networks responsible for learning action-outcome contingency.The model also showed corticostriatal plasticity consistent withlearning a new action in basal ganglia. We conclude that actionlearning is underpinned by a complex interplay of plasticity andstimulus salience, and that our model contains many of the elementsfor biological action discovery to take place.
Modelling of Patterns in Space and Time
Murray, James
1984-01-01
This volume contains a selection of papers presented at the work shop "Modelling of Patterns in Space and Time", organized by the 80nderforschungsbereich 123, "8tochastische Mathematische Modelle", in Heidelberg, July 4-8, 1983. The main aim of this workshop was to bring together physicists, chemists, biologists and mathematicians for an exchange of ideas and results in modelling patterns. Since the mathe matical problems arising depend only partially on the particular field of applications the interdisciplinary cooperation proved very useful. The workshop mainly treated phenomena showing spatial structures. The special areas covered were morphogenesis, growth in cell cultures, competition systems, structured populations, chemotaxis, chemical precipitation, space-time oscillations in chemical reactors, patterns in flames and fluids and mathematical methods. The discussions between experimentalists and theoreticians were especially interesting and effective. The editors hope that these proceedings reflect ...
Access Nets: Modeling Access to Physical Spaces
Frohardt, Robert; Chang, Bor-Yuh Evan; Sankaranarayanan, Sriram
Electronic, software-managed mechanisms using, for example, radio-frequency identification (RFID) cards, enable great flexibility in specifying access control policies to physical spaces. For example, access rights may vary based on time of day or could differ in normal versus emergency situations. With such fine-grained control, understanding and reasoning about what a policy permits becomes surprisingly difficult requiring knowledge of permission levels, spatial layout, and time. In this paper, we present a formal modeling framework, called AccessNets, suitable for describing a combination of access permissions, physical spaces, and temporal constraints. Furthermore, we provide evidence that model checking techniques are effective in reasoning about physical access control policies. We describe our results from a tool that uses reachability analysis to validate security policies.
Data Model Management for Space Information Systems
Hughes, J. Steven; Crichton, Daniel J.; Ramirez, Paul; Mattmann, chris
2006-01-01
The Reference Architecture for Space Information Management (RASIM) suggests the separation of the data model from software components to promote the development of flexible information management systems. RASIM allows the data model to evolve independently from the software components and results in a robust implementation that remains viable as the domain changes. However, the development and management of data models within RASIM are difficult and time consuming tasks involving the choice of a notation, the capture of the model, its validation for consistency, and the export of the model for implementation. Current limitations to this approach include the lack of ability to capture comprehensive domain knowledge, the loss of significant modeling information during implementation, the lack of model visualization and documentation capabilities, and exports being limited to one or two schema types. The advent of the Semantic Web and its demand for sophisticated data models has addressed this situation by providing a new level of data model management in the form of ontology tools. In this paper we describe the use of a representative ontology tool to capture and manage a data model for a space information system. The resulting ontology is implementation independent. Novel on-line visualization and documentation capabilities are available automatically, and the ability to export to various schemas can be added through tool plug-ins. In addition, the ingestion of data instances into the ontology allows validation of the ontology and results in a domain knowledge base. Semantic browsers are easily configured for the knowledge base. For example the export of the knowledge base to RDF/XML and RDFS/XML and the use of open source metadata browsers provide ready-made user interfaces that support both text- and facet-based search. This paper will present the Planetary Data System (PDS) data model as a use case and describe the import of the data model into an ontology tool
Data Model Management for Space Information Systems
Hughes, J. Steven; Crichton, Daniel J.; Ramirez, Paul; Mattmann, chris
2006-01-01
The Reference Architecture for Space Information Management (RASIM) suggests the separation of the data model from software components to promote the development of flexible information management systems. RASIM allows the data model to evolve independently from the software components and results in a robust implementation that remains viable as the domain changes. However, the development and management of data models within RASIM are difficult and time consuming tasks involving the choice of a notation, the capture of the model, its validation for consistency, and the export of the model for implementation. Current limitations to this approach include the lack of ability to capture comprehensive domain knowledge, the loss of significant modeling information during implementation, the lack of model visualization and documentation capabilities, and exports being limited to one or two schema types. The advent of the Semantic Web and its demand for sophisticated data models has addressed this situation by providing a new level of data model management in the form of ontology tools. In this paper we describe the use of a representative ontology tool to capture and manage a data model for a space information system. The resulting ontology is implementation independent. Novel on-line visualization and documentation capabilities are available automatically, and the ability to export to various schemas can be added through tool plug-ins. In addition, the ingestion of data instances into the ontology allows validation of the ontology and results in a domain knowledge base. Semantic browsers are easily configured for the knowledge base. For example the export of the knowledge base to RDF/XML and RDFS/XML and the use of open source metadata browsers provide ready-made user interfaces that support both text- and facet-based search. This paper will present the Planetary Data System (PDS) data model as a use case and describe the import of the data model into an ontology tool
Spreading Models in Banach Space Theory
Argyros, S A; Tyros, K
2010-01-01
We extend the classical Brunel-Sucheston definition of the spreading model by introducing the $\\mathcal{F}$-sequences $(x_s)_{s\\in\\mathcal{F}}$ in a Banach space and the plegma families in $\\mathcal{F}$ where $\\mathcal{F}$ is a regular thin family. The new concept yields a transfinite increasing hierarchy of classes of 1-subsymmetric sequences. We explore the corresponding theory and we present examples establishing this hierarchy and illustrating the limitation of the theory.
Relevance of Deconfined-Criticality Action in the Light of the J-Q Spin Model
Huang, Yuan; Chen, Kun; Deng, Youjin; Kuklov, Anatoly; Prokofev, Nikolay; Svistunov, Boris
2013-03-01
We perform large scale Monte Carlo simulations to study critical flows of 2D spin-1/2 J-Q model and 3D SU(2) symmetric discrete NCCP1 model, a.k.a. deconfined-critical-point (DCP) action. The flows of the J-Q model and the DCP action collapse in a significantly large region of system sizes (up to L ~ 60 - 80), implying that the DCP theory (in general) and the discrete NCCP1 model (in particular) correctly capture mesoscopic physics of the competition between the antiferromagnetic and valence-bond orders in quantum spin systems. At larger sizes we observe significant deviations between the two flows which both demonstrate strong violations of scale invariance. Furthermore, while the Neel state is perfectly space-time symmetric, the competing phase shows significant deviations from this symmetry. Possible scenarios are outlined. NSF PHY-1005543
Jointly structuring triadic spaces of meaning and action: book sharing from 3 months on.
Directory of Open Access Journals (Sweden)
Nicole eRossmanith
2014-12-01
Full Text Available This study explores the emergence of triadic interactions through the example of book sharing. As part of a naturalistic study, 10 infants were visited in their homes from 3-12 months. We report that (1 book sharing as a form of infant-caregiver-object interaction occurred from as early as 3 months. Using qualitative video analysis at a micro-level adapting methodologies from conversation and interaction analysis, we demonstrate that caregivers and infants practiced book sharing in a highly co-ordinated way, with caregivers carving out interaction units and shaping actions into action arcs and infants actively participating and co-ordinating their attention between mother and object from the beginning. We also (2 sketch a developmental trajectory of book sharing over the first year and show that the quality and dynamics of book sharing interactions underwent considerable change as the ecological situation was transformed in parallel with the infants' development of attention and motor skills. Social book sharing interactions reached an early peak at 6 months with the infants becoming more active in the coordination of attention between caregiver and book. From 7-9 months, the infants shifted their interest largely to solitary object exploration, in parallel with newly emerging postural and object manipulation skills, disrupting the social coordination and the cultural frame of book sharing. In the period from 9-12 months, social book interactions resurfaced, as infants began to effectively integrate object actions within the socially shared activity. In conclusion, to fully understand the development and qualities of triadic cultural activities such as book sharing, we need to look especially at the hitherto overlooked early period from 4-6 months, and investigate how shared spaces of meaning and action are structured together in and through interaction, creating the substrate for continuing cooperation and cultural learning.
Jointly structuring triadic spaces of meaning and action: book sharing from 3 months on.
Rossmanith, Nicole; Costall, Alan; Reichelt, Andreas F; López, Beatriz; Reddy, Vasudevi
2014-01-01
This study explores the emergence of triadic interactions through the example of book sharing. As part of a naturalistic study, 10 infants were visited in their homes from 3-12 months. We report that (1) book sharing as a form of infant-caregiver-object interaction occurred from as early as 3 months. Using qualitative video analysis at a micro-level adapting methodologies from conversation and interaction analysis, we demonstrate that caregivers and infants practiced book sharing in a highly co-ordinated way, with caregivers carving out interaction units and shaping actions into action arcs and infants actively participating and co-ordinating their attention between mother and object from the beginning. We also (2) sketch a developmental trajectory of book sharing over the first year and show that the quality and dynamics of book sharing interactions underwent considerable change as the ecological situation was transformed in parallel with the infants' development of attention and motor skills. Social book sharing interactions reached an early peak at 6 months with the infants becoming more active in the coordination of attention between caregiver and book. From 7 to 9 months, the infants shifted their interest largely to solitary object exploration, in parallel with newly emerging postural and object manipulation skills, disrupting the social coordination and the cultural frame of book sharing. In the period from 9 to 12 months, social book interactions resurfaced, as infants began to effectively integrate manual object actions within the socially shared activity. In conclusion, to fully understand the development and qualities of triadic cultural activities such as book sharing, we need to look especially at the hitherto overlooked early period from 4 to 6 months, and investigate how shared spaces of meaning and action are structured together in and through interaction, creating the substrate for continuing cooperation and cultural learning.
Can Participatory Action Research Create Value for Business Model Innovation?
DEFF Research Database (Denmark)
Sparre, Mogens; Rasmussen, Ole Horn; Fast, Alf Michael
Abstract: Participatory Action Research (PAR) has a longer academic history compared with the idea of business models (BMs). This paper indicates how industries gain by using the combined methodology. The research question "Can participatory action research create value for Business Model...... Innovation (BMI)?” – has been investigated from five different perspectives based upon The Business Model Cube and The Where to Look Model. Using both established and newly developed tools the paper presents how. Theory and data from two cases are presented and it is demonstrated how industry increase...... their monetary and/or non-monetary value creation doing BMI based upon PAR. The process is essential and using the methodology of PAR creates meaning. Behind the process, the RAR methodology and its link to BM and BMI may contribute to theory construction and creation of a common language in academia around...
Numerical modelling of elastic space tethers
DEFF Research Database (Denmark)
Kristiansen, Kristian Uldall; Palmer, P. L.; Roberts, R. M.
2012-01-01
In this paper the importance of the ill-posedness of the classical, non-dissipative massive tether model on an orbiting tether system is studied numerically. The computations document that via the regularisation of bending resistance a more reliable numerical integrator can be produced. Furthermore......, the numerical experiments of an orbiting tether system show that bending may introduce significant forces in some regions of phase space. Finally, numerical evidence for the existence of an almost invariant slow manifold of the singularly perturbed, regularised, non-dissipative massive tether model is provided...
String states, loops and effective actions in noncommutative field theory and matrix models
Directory of Open Access Journals (Sweden)
Harold C. Steinacker
2016-09-01
Full Text Available Refining previous work by Iso, Kawai and Kitazawa, we discuss bi-local string states as a tool for loop computations in noncommutative field theory and matrix models. Defined in terms of coherent states, they exhibit the stringy features of noncommutative field theory. This leads to a closed form for the 1-loop effective action in position space, capturing the long-range non-local UV/IR mixing for scalar fields. The formalism applies to generic fuzzy spaces. The non-locality is tamed in the maximally supersymmetric IKKT or IIB model, where it gives rise to supergravity. The linearized supergravity interactions are obtained directly in position space at one loop using string states on generic noncommutative branes.
String states, loops and effective actions in noncommutative field theory and matrix models
Energy Technology Data Exchange (ETDEWEB)
Steinacker, Harold C., E-mail: harold.steinacker@univie.ac.at
2016-09-15
Refining previous work by Iso, Kawai and Kitazawa, we discuss bi-local string states as a tool for loop computations in noncommutative field theory and matrix models. Defined in terms of coherent states, they exhibit the stringy features of noncommutative field theory. This leads to a closed form for the 1-loop effective action in position space, capturing the long-range non-local UV/IR mixing for scalar fields. The formalism applies to generic fuzzy spaces. The non-locality is tamed in the maximally supersymmetric IKKT or IIB model, where it gives rise to supergravity. The linearized supergravity interactions are obtained directly in position space at one loop using string states on generic noncommutative branes.
Geant4 models for space radiation environment.
Ivantchenko, Anton; Nieminen, Petteri; Incerti, Sebastien; Santin, Giovanni; Ivantchenko, Vladimir; Grichine, Vladimir; Allison, John
The space radiation environment includes wide varieties of particles from electrons to heavy ions. In order to correctly predict the dose received by astronauts and devices the simulation models must have good applicability and produce accurate results from 10 MeV/u up to 10 GeV/u, where the most radioactive hazardous particles are present in the spectra. Appropriate models should also provide a good description of electromagnetic interactions down to very low energies (10 eV/u - 10 MeV/u) for understanding the damage mechanisms due to long-term low doses. Predictions of biological dose during long interplanetary journeys also need models for hadronic interactions of energetic heavy ions extending higher energies (10 GeV/u - 100 GeV/u, but possibly up to 1 TeV/u). Geant4 is a powerful toolkit, which in some areas well surpasses the needs from space radiation studies, while in other areas is being developed and/or validated to properly cover the modelling requirements outlined above. Our activities in ESA projects deal with the research and development of both Geant4 hadronic and electromagnetic physics. Recently the scope of verification tests and benchmarks has been extended. Hadronic tests and benchmarks run proton, pion, and ion interactions with matter at various energies. In the Geant4 hadronic sub-libraries, the most accurate cross sections have been identified and selected as a default for all particle types relevant to space applications. Significant developments were carried out for ion/ion interaction models. These now allow one to perform Geant4 simulations for all particle types and energies relevant to space applications. For the validation of ion models the hadronic testing suite for ion interactions was significantly extended. In this work the results of benchmarking versus data in a wide energy range for projectile protons and ions will be shown and discussed. Here we show results of the tests runs and their precision. Recommendations for Geant4
Model reduction for Space Station Freedom
Williams, Trevor
1992-01-01
Model reduction is an important practical problem in the control of flexible spacecraft, and a considerable amount of work has been carried out on this topic. Two of the best known methods developed are modal truncation and internal balancing. Modal truncation is simple to implement but can give poor results when the structure possesses clustered natural frequencies, as often occurs in practice. Balancing avoids this problem but has the disadvantages of high computational cost, possible numerical sensitivity problems, and no physical interpretation for the resulting balanced 'modes'. The purpose of this work is to examine the performance of the subsystem balancing technique developed by the investigator when tested on a realistic flexible space structure, in this case a model of the Permanently Manned Configuration (PMC) of Space Station Freedom. This method retains the desirable properties of standard balancing while overcoming the three difficulties listed above. It achieves this by first decomposing the structural model into subsystems of highly correlated modes. Each subsystem is approximately uncorrelated from all others, so balancing them separately and then combining yields comparable results to balancing the entire structure directly. The operation count reduction obtained by the new technique is considerable: a factor of roughly r(exp 2) if the system decomposes into r equal subsystems. Numerical accuracy is also improved significantly, as the matrices being operated on are of reduced dimension, and the modes of the reduced-order model now have a clear physical interpretation; they are, to first order, linear combinations of repeated-frequency modes.
Edgeworth streaming model for redshift space distortions
Uhlemann, Cora
2015-01-01
We derive the Edgeworth streaming model (ESM) for the redshift space correlation function starting from an arbitrary distribution function for biased tracers of dark matter by considering its two-point statistics and show that it reduces to the Gaussian streaming model (GSM) when neglecting non-Gaussianities. We test the accuracy of the GSM and ESM independent of perturbation theory using the Horizon Run 2 N-body halo catalog. While the monopole of the redshift space halo correlation function is well described by the GSM, higher multipoles improve upon including the leading order non-Gaussian correction in the ESM: the GSM quadrupole breaks down on scales below 30 Mpc/h whereas the ESM stays accurate to 2% within statistical errors down to 10 Mpc/h. To predict the scale dependent functions entering the streaming model we employ Convolution Lagrangian perturbation theory (CLPT) based on the dust model and local Lagrangian bias. Since dark matter halos carry an intrinsic length scale given by their Lagrangian r...
Modeling utilization distributions in space and time.
Keating, Kim A; Cherry, Steve
2009-07-01
W. Van Winkle defined the utilization distribution (UD) as a probability density that gives an animal's relative frequency of occurrence in a two-dimensional (x, y) plane. We extend Van Winkle's work by redefining the UD as the relative frequency distribution of an animal's occurrence in all four dimensions of space and time. We then describe a product kernel model estimation method, devising a novel kernel from the wrapped Cauchy distribution to handle circularly distributed temporal covariates, such as day of year. Using Monte Carlo simulations of animal movements in space and time, we assess estimator performance. Although not unbiased, the product kernel method yields models highly correlated (Pearson's r = 0.975) with true probabilities of occurrence and successfully captures temporal variations in density of occurrence. In an empirical example, we estimate the expected UD in three dimensions (x, y, and t) for animals belonging to each of two distinct bighorn sheep (Ovis canadensis) social groups in Glacier National Park, Montana, USA. Results show the method can yield ecologically informative models that successfully depict temporal variations in density of occurrence for a seasonally migratory species. Some implications of this new approach to UD modeling are discussed.
Correlators of Matrix Models on Homogeneous Spaces
Kitazawa, Y; Tomino, D; Kitazawa, Yoshihisa; Takayama, Yastoshi; Tomino, Dan
2004-01-01
We investigate the correlators of TrA_{mu}A_{nu} in matrix models on homogeneous spaces: S^2 and S^2 x S^2. Their expectation value is a good order parameter to measure the geometry of the space on which non-commutative gauge theory is realized. They also serve as the Wilson lines which carry the minimum momentum. We develop an efficient procedure to calculate them through 1PI diagrams. We determine the large N scaling behavior of the correlators. The order parameter shows that fuzzy S^2 x S^2 acquires a 4 dimensional fractal structure in contrast to fuzzy S^2. We also find that the two point functions exhibit logarithmic scaling violations.
Cognitive engineering models in space systems
Mitchell, Christine M.
1993-01-01
NASA space systems, including mission operations on the ground and in space, are complex, dynamic, predominantly automated systems in which the human operator is a supervisory controller. Models of cognitive functions in complex systems are needed to describe human performance and form the theoretical basis of operator workstation design, including displays, controls, and decision aids. Currently, there several candidate modeling methodologies. They include the Rasmussen abstraction/aggregation hierarchy and decision ladder, the goal-means network, the problem behavior graph, and the operator function model. The research conducted under the sponsorship of this grant focuses on the extension of the theoretical structure of the operator function model and its application to NASA Johnson mission operations and space station applications. The initial portion of this research consists of two parts. The first is a series of technical exchanges between NASA Johnson and Georgia Tech researchers. The purpose is to identify candidate applications for the current operator function model; prospects include mission operations and the Data Management System Testbed. The second portion will address extensions of the operator function model to tailor it to the specific needs of Johnson applications. At this point, we have accomplished two things. During a series of conversations with JSC researchers, we have defined the technical goal of the research supported by this grant to be the structural definition of the operator function model and its computer implementation, OFMspert. Both the OFM and OFMspert have matured to the point that they require infrastructure to facilitate use by researchers not involved in the evolution of the tools. The second accomplishment this year was the identification of the Payload Deployment and Retrieval System (PDRS) as a candidate system for the case study. In conjunction with government and contractor personnel in the Human-Computer Interaction Lab
A discrete-space urban model with environmental amenities
Liaila Tajibaeva; Robert G. Haight; Stephen Polasky
2008-01-01
This paper analyzes the effects of providing environmental amenities associated with open space in a discrete-space urban model and characterizes optimal provision of open space across a metropolitan area. The discrete-space model assumes distinct neighborhoods in which developable land is homogeneous within a neighborhood but heterogeneous across neighborhoods. Open...
Approximate Methods for State-Space Models.
Koyama, Shinsuke; Pérez-Bolde, Lucia Castellanos; Shalizi, Cosma Rohilla; Kass, Robert E
2010-03-01
State-space models provide an important body of techniques for analyzing time-series, but their use requires estimating unobserved states. The optimal estimate of the state is its conditional expectation given the observation histories, and computing this expectation is hard when there are nonlinearities. Existing filtering methods, including sequential Monte Carlo, tend to be either inaccurate or slow. In this paper, we study a nonlinear filter for nonlinear/non-Gaussian state-space models, which uses Laplace's method, an asymptotic series expansion, to approximate the state's conditional mean and variance, together with a Gaussian conditional distribution. This Laplace-Gaussian filter (LGF) gives fast, recursive, deterministic state estimates, with an error which is set by the stochastic characteristics of the model and is, we show, stable over time. We illustrate the estimation ability of the LGF by applying it to the problem of neural decoding and compare it to sequential Monte Carlo both in simulations and with real data. We find that the LGF can deliver superior results in a small fraction of the computing time.
Microblog Sentiment Analysis with Emoticon Space Model
Institute of Scientific and Technical Information of China (English)
姜飞; 刘奕群; 孙甲申; 朱璇; 张敏; 马少平
2015-01-01
Emoticons have been widely employed to express different types of moods, emotions, and feelings in microblog environments. They are therefore regarded as one of the most important signals for microblog sentiment analysis. Most existing studies use several emoticons that convey clear emotional meanings as noisy sentiment labels or similar sentiment indicators. However, in practical microblog environments, tens or even hundreds of emoticons are frequently adopted and all emoticons have their own unique emotional meanings. Besides, a considerable number of emoticons do not have clear emotional meanings. An improved sentiment analysis model should not overlook these phenomena. Instead of manually assigning sentiment labels to several emoticons that convey relatively clear meanings, we propose the emoticon space model (ESM) that leverages more emoticons to construct word representations from a massive amount of unlabeled data. By projecting words and microblog posts into an emoticon space, the proposed model helps identify subjectivity, polarity, and emotion in microblog environments. The experimental results for a public microblog benchmark corpus (NLP&CC 2013) indicate that ESM effectively leverages emoticon signals and outperforms previous state-of-the-art strategies and benchmark best runs.
Directory of Open Access Journals (Sweden)
Stefano eTriberti
2016-01-01
Full Text Available Recent neuropsychological evidence suggest that a key role in linking perceptions and intentions is played by sense of presence. Despite this phenomenon having been studied primarily in the field of virtual reality (conceived as the illusion of being in the virtual space, recent research highlighted that it is a fundamental feature of everyday experience. Specifically, the function of presence as a cognitive process is to locate the Self in a physical space or situation, based on the perceived possibility to act in it; so, the variations in sense of presence allow one to continuously adapt his own action to the external environment. Indeed intentions, as the cognitive antecedents of action, are not static representations of the desired outcomes, but dynamic processes able to adjust their own representational content according to the opportunities/restrictions emerging in the environment. Focusing on the peculiar context of action mediated by interactive technologies, we here propose a theoretical model showing how each level of an intentional hierarchy (future-directed; present directed; and motor intentions can interlock with environmental affordances in order to promote a continuous stream of action and activity.
Re-modeling Chara action potential: II. The action potential form under salinity stress
Directory of Open Access Journals (Sweden)
Mary Jane Beilby
2017-04-01
Full Text Available In part I we established Thiel-Beilby model of the Chara action potential (AP. In part II the AP is investigated in detail at the time of saline stress. Even very short exposure of salt-sensitive Chara cells to artificial pond water with 50 mM NaCl (Saline APW modified the AP threshold and drastically altered the AP form. Detailed modeling of 14 saline APs from 3 cells established that both the Ca2+ pump and the Ca2+ channels on internal stores seem to be affected, with the changes sometimes cancelling and sometimes re-enforcing each other, leading to APs with long durations and very complex forms. The exposure to salinity offers further insights into AP mechanism and suggests future experiments. The prolonged APs lead to greater loss of chloride and potassium ions, compounding the effects of saline stress.
Integrated Space Asset Management Database and Modeling
Gagliano, L.; MacLeod, T.; Mason, S.; Percy, T.; Prescott, J.
The Space Asset Management Database (SAM-D) was implemented in order to effectively track known objects in space by ingesting information from a variety of databases and performing calculations to determine the expected position of the object at a specified time. While SAM-D performs this task very well, it is limited by technology and is not available outside of the local user base. Modeling and simulation can be powerful tools to exploit the information contained in SAM-D. However, the current system does not allow proper integration options for combining the data with both legacy and new M&S tools. A more capable data management infrastructure would extend SAM-D to support the larger data sets to be generated by the COI. A service-oriented architecture model will allow it to easily expand to incorporate new capabilities, including advanced analytics, M&S tools, fusion techniques and user interface for visualizations. Based on a web-centric approach, the entire COI will be able to access the data and related analytics. In addition, tight control of information sharing policy will increase confidence in the system, which would encourage industry partners to provide commercial data. SIMON is a Government off the Shelf information sharing platform in use throughout DoD and DHS information sharing and situation awareness communities. SIMON providing fine grained control to data owners allowing them to determine exactly how and when their data is shared. SIMON supports a micro-service approach to system development, meaning M&S and analytic services can be easily built or adapted. It is uniquely positioned to fill this need as an information-sharing platform with a proven track record of successful situational awareness system deployments. Combined with the integration of new and legacy M&S tools, a SIMON-based architecture will provide a robust SA environment for the NASA SA COI that can be extended and expanded indefinitely. First Results of Coherent Uplink from a
Modeling Bivariate Longitudinal Hormone Profiles by Hierarchical State Space Models.
Liu, Ziyue; Cappola, Anne R; Crofford, Leslie J; Guo, Wensheng
2014-01-01
The hypothalamic-pituitary-adrenal (HPA) axis is crucial in coping with stress and maintaining homeostasis. Hormones produced by the HPA axis exhibit both complex univariate longitudinal profiles and complex relationships among different hormones. Consequently, modeling these multivariate longitudinal hormone profiles is a challenging task. In this paper, we propose a bivariate hierarchical state space model, in which each hormone profile is modeled by a hierarchical state space model, with both population-average and subject-specific components. The bivariate model is constructed by concatenating the univariate models based on the hypothesized relationship. Because of the flexible framework of state space form, the resultant models not only can handle complex individual profiles, but also can incorporate complex relationships between two hormones, including both concurrent and feedback relationship. Estimation and inference are based on marginal likelihood and posterior means and variances. Computationally efficient Kalman filtering and smoothing algorithms are used for implementation. Application of the proposed method to a study of chronic fatigue syndrome and fibromyalgia reveals that the relationships between adrenocorticotropic hormone and cortisol in the patient group are weaker than in healthy controls.
Multivariable Wind Modeling in State Space
DEFF Research Database (Denmark)
Sichani, Mahdi Teimouri; Pedersen, B. J.
2011-01-01
Turbulence of the incoming wind field is of paramount importance to the dynamic response of wind turbines. Hence reliable stochastic models of the turbulence should be available from which time series can be generated for dynamic response and structural safety analysis. In the paper an empirical...... cross-spectral density function for the along-wind turbulence component over the rotor plane is taken as the starting point. The spectrum is spatially discretized in terms of a Hermitian cross-spectral density matrix for the turbulence state vector which turns out not to be positive definite. Since...... the succeeding state space and ARMA modeling of the turbulence rely on the positive definiteness of the cross-spectral density matrix, the problem with the non-positive definiteness of such matrices is at first addressed and suitable treatments regarding it are proposed. From the adjusted positive definite cross...
Modeling Physarum space exploration using memristors
Ntinas, V.; Vourkas, I.; Sirakoulis, G. Ch; Adamatzky, A. I.
2017-05-01
Slime mold Physarum polycephalum optimizes its foraging behaviour by minimizing the distances between the sources of nutrients it spans. When two sources of nutrients are present, the slime mold connects the sources, with its protoplasmic tubes, along the shortest path. We present a two-dimensional mesh grid memristor based model as an approach to emulate Physarum’s foraging strategy, which includes space exploration and reinforcement of the optimally formed interconnection network in the presence of multiple aliment sources. The proposed algorithmic approach utilizes memristors and LC contours and is tested in two of the most popular computational challenges for Physarum, namely maze and transportation networks. Furthermore, the presented model is enriched with the notion of noise presence, which positively contributes to a collective behavior and enables us to move from deterministic to robust results. Consequently, the corresponding simulation results manage to reproduce, in a much better qualitative way, the expected transportation networks.
A probabilistic model of RNA conformational space
DEFF Research Database (Denmark)
Frellsen, Jes; Moltke, Ida; Thiim, Martin
2009-01-01
The increasing importance of non-coding RNA in biology and medicine has led to a growing interest in the problem of RNA 3-D structure prediction. As is the case for proteins, RNA 3-D structure prediction methods require two key ingredients: an accurate energy function and a conformational sampling...... procedure. Both are only partly solved problems. Here, we focus on the problem of conformational sampling. The current state of the art solution is based on fragment assembly methods, which construct plausible conformations by stringing together short fragments obtained from experimental structures. However...... efficient sampling of RNA conformations in continuous space, and with associated probabilities. We show that the model captures several key features of RNA structure, such as its rotameric nature and the distribution of the helix lengths. Furthermore, the model readily generates native-like 3-D...
Granger causality for state-space models.
Barnett, Lionel; Seth, Anil K
2015-04-01
Granger causality has long been a prominent method for inferring causal interactions between stochastic variables for a broad range of complex physical systems. However, it has been recognized that a moving average (MA) component in the data presents a serious confound to Granger causal analysis, as routinely performed via autoregressive (AR) modeling. We solve this problem by demonstrating that Granger causality may be calculated simply and efficiently from the parameters of a state-space (SS) model. Since SS models are equivalent to autoregressive moving average models, Granger causality estimated in this fashion is not degraded by the presence of a MA component. This is of particular significance when the data has been filtered, downsampled, observed with noise, or is a subprocess of a higher dimensional process, since all of these operations-commonplace in application domains as diverse as climate science, econometrics, and the neurosciences-induce a MA component. We show how Granger causality, conditional and unconditional, in both time and frequency domains, may be calculated directly from SS model parameters via solution of a discrete algebraic Riccati equation. Numerical simulations demonstrate that Granger causality estimators thus derived have greater statistical power and smaller bias than AR estimators. We also discuss how the SS approach facilitates relaxation of the assumptions of linearity, stationarity, and homoscedasticity underlying current AR methods, thus opening up potentially significant new areas of research in Granger causal analysis.
London, Leslie; Schneider, Helen
2012-01-01
While neoliberal globalisation is associated with increasing inequalities, global integration has simultaneously strengthened the dissemination of human rights discourse across the world. This paper explores the seeming contradiction that globalisation is conceived as disempowering nations states' ability to act in their population's interests, yet implementation of human rights obligations requires effective states to deliver socio-economic entitlements, such as health. Central to the actions required of the state to build a health system based on a human rights approach is the notion of accountability. Two case studies are used to explore the constraints on states meeting their human rights obligations regarding health, the first drawing on data from interviews with parliamentarians responsible for health in East and Southern Africa, and the second reflecting on the response to the HIV/AIDS epidemic in South Africa. The case studies illustrate the importance of a human rights paradigm in strengthening parliamentary oversight over the executive in ways that prioritise pro-poor protections and in increasing leverage for resources for the health sector within parliamentary processes. Further, a rights framework creates the space for civil society action to engage with the legislature to hold public officials accountable and confirms the importance of rights as enabling civil society mobilization, reinforcing community agency to advance health rights for poor communities. In this context, critical assessment of state incapacity to meet claims to health rights raises questions as to the diffusion of accountability rife under modern international aid systems. Such diffusion of accountability opens the door to 'cunning' states to deflect rights claims of their populations. We argue that human rights, as both a normative framework for legal challenges and as a means to create room for active civil society engagement provide a means to contest both the real and the
Preliminaries to a Social-Semiotic Model of Communicative Action
Directory of Open Access Journals (Sweden)
Antonio SANDU
2015-12-01
Full Text Available The purpose of this article is to bring contributions to the elaboration of a social-semiotic model of social constructionism, which will make a synthesis between the theory of communicative action and the theories of social-constructionist semiotic model?, based on the postulation of a social universe in a network of communicative interdependencies developed on levels of reality. The interpretative model we propose comes to conceptualize the particularities of the sociological analysis of the transmodern society, seen as a knowledge-based society, placed at the interference with the postmodern society; that of generalized permissiveness. The model proposed aims at a constructionist-fractalic (al? analysis (of deconstruction-reconstruction type of the interpretative drift of social constructs, under the empire of different constructive instances.
Orland-Barak, Lily; Becher, Ayelet
2011-01-01
In this article we offer an extended reading of an action research model in the context of mentored learning in preservice education in Israel. Our reading attends both to how a particular form of action research plays out in participants' constructions of the practice of mentoring and mentored learning and how such constructions can be understood…
Sweetman, Joseph; Whitmarsh, Lorraine E
2016-01-01
Recent work has suggested that our cognitive biases and moral psychology may pose significant barriers to tackling climate change. Here, we report evidence that through status and group-based social influence processes, and our moral sense of justice, it may be possible to employ such characteristics of the human mind in efforts to engender pro-environmental action. We draw on applied work demonstrating the efficacy of social modeling techniques in order to examine the indirect effects of social model status and group membership (through perceptions of efficacy, pro-environmental social identity and moral judgments of how fair it is for individuals to perform particular pro-environmental actions) on pro-environmental action tendencies. We find evidence that high- (vs. low-) status models increase pro-environmental action, in part, through making such actions seem morally fairer to undertake. This effect of high-status models only occurs when they share a meaningful ingroup membership with the target of influence. Further, we find evidence that this conditional effect of high-status models may also have a direct impact on action tendencies. While the exact behaviors that are influenced may vary across student and non-student samples, we argue that a focus on the "justice pathway" to action and the social-cognitive features of models may offer a good opportunity for cognitive and behavioral scientists to integrate insights from basic research with those stemming from more applied research efforts.
An introduction to state space modeling (in Russian)
Alexander Tsyplakov
2011-01-01
Many time series models, primarily various models with unobservable components, can be represented in a so called state space form. A state space model is a powerful tool that allows one to apply to the original model a wide range of standard procedures including estimation and forecasting. This essay provides a survey of this universal class of models and related procedures.
Exact solutions of SO(3) non-linear sigma model in a conic space background
Bezerra, V B; Romero, C
2005-01-01
We consider a nonlinear sigma model coupled to the metric of a conic space. We obtain restrictions for a nonlinear sigma model to be a source of the conic space. We then study nonlinear sigma model in the conic space background. We find coordinate transformations which reduce the chiral fields equations in the conic space background to field equations in Minkowski spacetime. This enables us to apply the same methods for obtaining exact solutions in Minkowski spacetime to the case of a conic spacetime. In the case the solutions depend on two spatial coordinates we employ Ivanov's geometrical ansatz. We give a general analysis and also present classes of solutions in which there is dependence on three and four coordinates. We discuss with special attention the intermediate instanton and meron solutions and their analogous in the conic space. We find differences in the total actions and topological charges of these solutions and discuss the role of the deficit angle.
Modeling the reconstructed BAO in Fourier space
Seo, Hee-Jong; Beutler, Florian; Ross, Ashley J.; Saito, Shun
2016-08-01
The density field reconstruction technique, which partially reverses the non-linear degradation of the Baryon acoustic oscillation (BAO) feature in the galaxy redshift surveys, has been successful in substantially improving the cosmology constraints from recent surveys such as Baryon Oscillation Spectroscopic Survey (BOSS). We estimate the efficiency of the method as a function of various reconstruction details. To directly quantify the BAO information in non-linear density fields before and after reconstruction, we calculate the cross-correlations (i.e. propagators) of the pre(post)-reconstructed density field with the initial linear field using a mock sample that mimics the clustering of the BOSS galaxies. The results directly provide the BAO damping as a function of wavenumber that can be implemented into the Fisher matrix analysis. We focus on investigating the dependence of the propagator on a choice of smoothing filters and on two major different conventions of the redshift-space density field reconstruction that have been used in literature. By estimating the BAO signal to noise for each case, we predict constraints on the angular diameter distance and Hubble parameter using the Fisher matrix analysis. We thus determine an optimal Gaussian smoothing filter scale for the signal-to-noise level of the BOSS CMASS. We also present appropriate BAO fitting models for different reconstruction methods based on the first- and second-order Lagrangian perturbation theory in Fourier space. Using the mock data, we show that the modified BAO fitting model can substantially improve the accuracy of the BAO position in the best fits as well as the goodness of the fits.
Modeling missing data in knowledge space theory.
de Chiusole, Debora; Stefanutti, Luca; Anselmi, Pasquale; Robusto, Egidio
2015-12-01
Missing data are a well known issue in statistical inference, because some responses may be missing, even when data are collected carefully. The problem that arises in these cases is how to deal with missing data. In this article, the missingness is analyzed in knowledge space theory, and in particular when the basic local independence model (BLIM) is applied to the data. Two extensions of the BLIM to missing data are proposed: The former, called ignorable missing BLIM (IMBLIM), assumes that missing data are missing completely at random; the latter, called missing BLIM (MissBLIM), introduces specific dependencies of the missing data on the knowledge states, thus assuming that the missing data are missing not at random. The IMBLIM and the MissBLIM modeled the missingness in a satisfactory way, in both a simulation study and an empirical application, depending on the process that generates the missingness: If the missing data-generating process is of type missing completely at random, then either IMBLIM or MissBLIM provide adequate fit to the data. However, if the pattern of missingness is functionally dependent upon unobservable features of the data (e.g., missing answers are more likely to be wrong), then only a correctly specified model of the missingness distribution provides an adequate fit to the data.
Space Station crew safety - Human factors model
Cohen, M. M.; Junge, M. K.
1984-01-01
A model of the various human factors issues and interactions that might affect crew safety is developed. The first step addressed systematically the central question: How is this Space Station different from all other spacecraft? A wide range of possible issue was identified and researched. Five major topics of human factors issues that interacted with crew safety resulted: Protocols, Critical Habitability, Work Related Issues, Crew Incapacitation and Personal Choice. Second, an interaction model was developed that would show some degree of cause and effect between objective environmental or operational conditions and the creation of potential safety hazards. The intermediary steps between these two extremes of causality were the effects on human performance and the results of degraded performance. The model contains three milestones: stressor, human performance (degraded) and safety hazard threshold. Between these milestones are two countermeasure intervention points. The first opportunity for intervention is the countermeasure against stress. If this countermeasure fails, performance degrades. The second opportunity for intervention is the countermeasure against error. If this second countermeasure fails, the threshold of a potential safety hazard may be crossed.
A dynamic appearance descriptor approach to facial actions temporal modeling.
Jiang, Bihan; Valstar, Michel; Martinez, Brais; Pantic, Maja
2014-02-01
Both the configuration and the dynamics of facial expressions are crucial for the interpretation of human facial behavior. Yet to date, the vast majority of reported efforts in the field either do not take the dynamics of facial expressions into account, or focus only on prototypic facial expressions of six basic emotions. Facial dynamics can be explicitly analyzed by detecting the constituent temporal segments in Facial Action Coding System (FACS) Action Units (AUs)-onset, apex, and offset. In this paper, we present a novel approach to explicit analysis of temporal dynamics of facial actions using the dynamic appearance descriptor Local Phase Quantization from Three Orthogonal Planes (LPQ-TOP). Temporal segments are detected by combining a discriminative classifier for detecting the temporal segments on a frame-by-frame basis with Markov Models that enforce temporal consistency over the whole episode. The system is evaluated in detail over the MMI facial expression database, the UNBC-McMaster pain database, the SAL database, the GEMEP-FERA dataset in database-dependent experiments, in cross-database experiments using the Cohn-Kanade, and the SEMAINE databases. The comparison with other state-of-the-art methods shows that the proposed LPQ-TOP method outperforms the other approaches for the problem of AU temporal segment detection, and that overall AU activation detection benefits from dynamic appearance information.
Linking knowledge and action through mental models of sustainable agriculture.
Hoffman, Matthew; Lubell, Mark; Hillis, Vicken
2014-09-01
Linking knowledge to action requires understanding how decision-makers conceptualize sustainability. This paper empirically analyzes farmer "mental models" of sustainability from three winegrape-growing regions of California where local extension programs have focused on sustainable agriculture. The mental models are represented as networks where sustainability concepts are nodes, and links are established when a farmer mentions two concepts in their stated definition of sustainability. The results suggest that winegrape grower mental models of sustainability are hierarchically structured, relatively similar across regions, and strongly linked to participation in extension programs and adoption of sustainable farm practices. We discuss the implications of our findings for the debate over the meaning of sustainability, and the role of local extension programs in managing knowledge systems.
Gauge Potts model with generalized action: A Monte Carlo analysis
Energy Technology Data Exchange (ETDEWEB)
Fanchiotti, H.; Canal, C.A.G.; Sciutto, S.J.
1985-08-15
Results of a Monte Carlo calculation on the q-state gauge Potts model in d dimensions with a generalized action involving planar 1 x 1, plaquette, and 2 x 1, fenetre, loop interactions are reported. For d = 3 and q = 2, first- and second-order phase transitions are detected. The phase diagram for q = 3 presents only first-order phase transitions. For d = 2, a comparison with analytical results is made. Here also, the behavior of the numerical simulation in the vicinity of a second-order transition is analyzed.
International Space Station Radiation Shielding Model Development
Qualls, G. D.; Wilson, J. W.; Sandridge, C.; Cucinotta, F. A.; Nealy, J. E.; Heinbockel, J. H.; Hugger, C. P.; Verhage, J.; Anderson, B. M.; Atwell, W.
2001-01-01
The projected radiation levels within the International Space Station (ISS) have been criticized by the Aerospace Safety Advisory Panel in their report to the NASA Administrator. Methods for optimal reconfiguration and augmentation of the ISS shielding are now being developed. The initial steps are to develop reconfigurable and realistic radiation shield models of the ISS modules, develop computational procedures for the highly anisotropic radiation environment, and implement parametric and organizational optimization procedures. The targets of the redesign process are the crew quarters where the astronauts sleep and determining the effects of ISS shadow shielding of an astronaut in a spacesuit. The ISS model as developed will be reconfigurable to follow the ISS. Swapping internal equipment rack assemblies via location mapping tables will be one option for shield optimization. Lightweight shield augmentation materials will be optimally fit to crew quarter areas using parametric optimization procedures to minimize the augmentation shield mass. The optimization process is being integrated into the Intelligence Synthesis Environment s (ISE s) immersive simulation facility at the Langley Research Center and will rely on High Performance Computing and Communication (HPCC) for rapid evaluation of shield parameter gradients.
Chulaki, A.; Kuznetsova, M. M.; Rastaetter, L.; MacNeice, P. J.; Shim, J. S.; Pulkkinen, A. A.; Taktakishvili, A.; Mays, M. L.; Mendoza, A. M. M.; Zheng, Y.; Mullinix, R.; Collado-Vega, Y. M.; Maddox, M. M.; Pembroke, A. D.; Wiegand, C.
2015-12-01
Community Coordinated Modeling Center (CCMC) is a NASA affiliated interagency partnership with the primary goal of aiding the transition of modern space science models into space weather forecasting while supporting space science research. Additionally, over the past ten years it has established itself as a global space science education resource supporting undergraduate and graduate education and research, and spreading space weather awareness worldwide. A unique combination of assets, capabilities and close ties to the scientific and educational communities enable this small group to serve as a hub for raising generations of young space scientists and engineers. CCMC resources are publicly available online, providing unprecedented global access to the largest collection of modern space science models (developed by the international research community). CCMC has revolutionized the way simulations are utilized in classrooms settings, student projects, and scientific labs and serves hundreds of educators, students and researchers every year. Another major CCMC asset is an expert space weather prototyping team primarily serving NASA's interplanetary space weather needs. Capitalizing on its unrivaled capabilities and experiences, the team provides in-depth space weather training to students and professionals worldwide, and offers an amazing opportunity for undergraduates to engage in real-time space weather monitoring, analysis, forecasting and research. In-house development of state-of-the-art space weather tools and applications provides exciting opportunities to students majoring in computer science and computer engineering fields to intern with the software engineers at the CCMC while also learning about the space weather from the NASA scientists.
The Diversity of Enterprise Modeling – a Taxonomy for Enterprise Modeling Actions
Directory of Open Access Journals (Sweden)
Ulf Seigerroth
2015-10-01
Full Text Available Both researchers and practitioners have recognized the need for developed knowledge about enterprise modeling. Therefore it is necessary to increase the understanding of various actions that are performed during enterprise modeling, their meaning, and their diversity. This paper proposes a taxonomy with a conceptual structure in two dimensions (hierarchy and process that could be used to increase the knowledge about enterprise modeling actions. The taxonomy introduces a terminology that enables a better understanding of the modeling actions for a clear purpose. One important aspect of the taxonomy is to create visibility and traceability of decisions made during enterprise modeling activities. These modeling decisions have previously been of a more tacit nature and the taxonomy is supposed to make the rationale behind different modeling decisions explicit and understandable.
RESULTS OF INTERBANK EXCHANGE RATES FORECASTING USING STATE SPACE MODEL
Directory of Open Access Journals (Sweden)
Muhammad Kashif
2008-07-01
Full Text Available This study evaluates the performance of three alternative models for forecasting daily interbank exchange rate of U.S. dollar measured in Pak rupees. The simple ARIMA models and complex models such as GARCH-type models and a state space model are discussed and compared. Four different measures are used to evaluate the forecasting accuracy. The main result is the state space model provides the best performance among all the models.
Complex Dynamic Thresholds and Generation of the Action Potentials in the Neural-Activity Model
Kirillov, S. Yu.; Nekorkin, V. I.
2016-05-01
This work is devoted to studying the processes of activation of the neurons whose excitation thresholds are not constant and vary in time (the so-called dynamic thresholds). The neuron dynamics is described by the FitzHugh-Nagumo model with nonlinear behavior of the recovery variable. The neuron response to the external pulsed activating action in the presence of a slowly varying synaptic current is studied within the framework of this model. The structure of the dynamic threshold is studied and its properties depending on the external-action parameters are established. It is found that the formation of the "folds" in the separatrix threshold manifold in the model phase space is a typical feature of the complex dynamic threshold. High neuron sensitivity to the action of the comparatively weak slow control signals is established. This explains the capability of the neurons to perform flexible tuning of their selective properties for detecting various external signals in sufficiently short times (of the order of duration of several spikes).
Evaluating model of frozen soil environment change under engineering actions
Institute of Scientific and Technical Information of China (English)
WU; Qingbai(吴青柏); ZHU; Yuanlin(朱元林); LIU; Yongzhi(刘永智)
2002-01-01
The change of frozen soil environment is evaluated by permafrost thermal stability, thermal thaw sensibility and surface landscape stability and the quantitatively evaluating model of frozen soil environment is proposed in this paper. The evaluating model of frozen soil environment is calculated by 28 ground temperature measurements along Qinghai-Xizang Highway. The relationships of thermal thaw sensibility and freezing and thawing processes and seasonally thawing depth, thermal stability and permafrost table temperature, mean annual ground temperature and seasonally thawing depth, and surface landscape stability and freezing and thawing hazards and their forming possibility are analyzed. The results show that thermal stability, thermal thaw sensibility and surface landscape stability can be used to evaluate and predict the change of frozen soil environment under human engineering action.
Pressure wave model for action potential propagation in excitable cells
Rvachev, M M
2003-01-01
Speed of propagation of small-amplitude pressure waves through the cytoplasmic interior of myelinated and unmyelinated axons of different diameters is theoretically estimated and is found to generally agree with the action potential (AP) conduction velocities. This remarkable coincidence allows to surmise a model in which AP spread along axon is propelled not by straggling ionic currents as in the widely accepted local circuit theory, but by mechanoactivation of the membrane ion channels by a traveling pressure pulse. Hydraulic pulses propagating in the viscous axoplasm are calculated to decay over ~1 mm distances, and it is further hypothesized that it is the role of influxing during the AP calcium ions to activate membrane skeletal protein network attached to the membrane cytoplasmic side for a brief radial contraction amplifying the pressure pulse and preventing its decay. The model correctly predicts that the AP conduction velocity should vary as the one-half power of axon diameter for large unmyelinated ...
Optimization using surrogate models - by the space mapping technique
DEFF Research Database (Denmark)
Søndergaard, Jacob
2003-01-01
mapping surrogate has a lower approximation error for long steps. For short steps, however, the Taylor model of the expensive model is best, due to exact interpolation at the model origin. Five algorithms for space mapping optimization are presented and the numerical performance is evaluated. Three...... conditions are satisfied. So hybrid methods, combining the space mapping technique with classical optimization methods, should be used if convergence to high accuracy is wanted. Approximation abilities of the space mapping surrogate are compared with those of a Taylor model of the expensive model. The space...
Optimization using surrogate models - by the space mapping technique
DEFF Research Database (Denmark)
Søndergaard, Jacob
2003-01-01
mapping surrogate has a lower approximation error for long steps. For short steps, however, the Taylor model of the expensive model is best, due to exact interpolation at the model origin. Five algorithms for space mapping optimization are presented and the numerical performance is evaluated. Three...... conditions are satisfied. So hybrid methods, combining the space mapping technique with classical optimization methods, should be used if convergence to high accuracy is wanted. Approximation abilities of the space mapping surrogate are compared with those of a Taylor model of the expensive model. The space...
Equivariance on Discrete Space and Yang-Mills-Higgs Model
Ikemori, Hitoshi; Matsui, Yoshimitsu; Otsu, Hideharu; Sato, Toshiro
2015-01-01
We introduce the basic equivariant quantity $Q$ in the gauge theory on the noncommutative descrete $Z_{2}$ space, which plays an important role for the equivariant dimensional reduction. If the gauge configuration of the ground state on the extra dimensional space is described by the equivariant $Q$, then the extra dimensional space is invisible. Especially, using the equivariance principle, we show that the Yang-Mills theory on $R^{2}\\times Z_{2}$ space is equivalent to the Yang-Mills-Higgs model on $R^{2}$ space. It can be said that this model is the simplest model of this type.
Phase lagging model of brain response to external stimuli - modeling of single action potential
Seetharaman, Karthik; Kulish, Vladimir V
2012-01-01
In this paper we detail a phase lagging model of brain response to external stimuli. The model is derived using the basic laws of physics like conservation of energy law. This model eliminates the paradox of instantaneous propagation of the action potential in the brain. The solution of this model is then presented. The model is further applied in the case of a single neuron and is verified by simulating a single action potential. The results of this modeling are useful not only for the fundamental understanding of single action potential generation, but also they can be applied in case of neuronal interactions where the results can be verified against the real EEG signal.
Space Particle Hazard Measurement and Modeling
2016-09-01
launch in 2012. Key Publication: • [54] ISO Standard 11221 Space Systems – Space Solar Panels – Spacecraft Charging Induced - Electrostatic...plasma [71]. Completed charge testing on 3 solar panel cover glass replacement candidates developed by the Advanced Space Power program in AFRL/RVS...of Lifetimes Against Pitch Angle Diffusion, J. Atmos. Solar -Terr. Phys., 71, 1647, doi:10.1016/j.jastp.2008.07.004, 2009. [18] Meredith, N. P., et
Enhanced surrogate models for statistical design exploiting space mapping technology
DEFF Research Database (Denmark)
Koziel, Slawek; Bandler, John W.; Mohamed, Achmed S.;
2005-01-01
We present advances in microwave and RF device modeling exploiting Space Mapping (SM) technology. We propose new SM modeling formulations utilizing input mappings, output mappings, frequency scaling and quadratic approximations. Our aim is to enhance circuit models for statistical analysis...
Macro Level Simulation Model Of Space Shuttle Processing
2000-01-01
The contents include: 1) Space Shuttle Processing Simulation Model; 2) Knowledge Acquisition; 3) Simulation Input Analysis; 4) Model Applications in Current Shuttle Environment; and 5) Model Applications for Future Reusable Launch Vehicles (RLV's). This paper is presented in viewgraph form.
DEFF Research Database (Denmark)
Clausen, Christian
2004-01-01
30 years. The paper provides an overview of Scandinavian research within technology and working life form a Danish perspective. A major contribution is con-cerned with a variety of strategies employed by social actors involved in action research pro-jects and their role in the social shaping...... of technology. The point is made that no single strat-egy have proved to provide an uncontested route for union or workers influence. Instead the Scandinavian experiences indicate, that a range of spaces, players and positions have been developed, providing opportunities for addressing questions related...
A Boolean action of C(M,U(1)) without a spatial model
Moore, Justin Tatch
2012-01-01
We will demonstrate that if M is an uncountable compact metric space, then there is an action of the Polish group of all continuous functions from M to U(1) on a separable probability algebra which preserves the measure and yet does not admit a point realization (in a standard probability space) in the sense of Mackey. This contrasts Mackey's point realization theorem for locally compact, second countable groups which asserts that any measure preserving Boolean action of a locally compact, second countable group on a separable probability algebra can be realized as an action on the points of a standard probability space.
Dynamic simulation of hydrodynamic model of drum level wave action and sloshing
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
In order to build the model of the drum level wave action and sloshing, based on the method of modularization modeling,the hydrodynamic model of drum level wave action and sloshing was developed, and dynamic simulation researches were carried out based on the model. The results indicate that both drum level and drum length have functional relations with period of drum level wave action and sloshing. When the drum level decreases or drum length increases, the period of drum level wave action and sloshing increases, density of liquid and number of sub-module division have little influence on the period of drum level wave action and sloshing. The model was validated by the analytical solution theory of liquid's wave action and sloshing in cuboid container, and the 3D graphics of drum level wave action and sloshing was also obtained. The model can dynamically reflect the rules of wave action and sloshing of water in the container exactly.
DEFF Research Database (Denmark)
Clausen, Christian
2004-01-01
30 years. The paper provides an overview of Scandinavian research within technology and working life form a Danish perspective. A major contribution is con-cerned with a variety of strategies employed by social actors involved in action research pro-jects and their role in the social shaping......This contribution explores a range of social spaces where unions and workers have played or potential can play a role in the local social shaping of IT and work. It will mainly be based on the authors own research and experiences within Scandinavian research on technology and working from the past...... of technology. The point is made that no single strat-egy have proved to provide an uncontested route for union or workers influence. Instead the Scandinavian experiences indicate, that a range of spaces, players and positions have been developed, providing opportunities for addressing questions related...
Space-time modeling of electricity spot prices
DEFF Research Database (Denmark)
Abate, Girum Dagnachew; Haldrup, Niels
In this paper we derive a space-time model for electricity spot prices. A general spatial Durbin model that incorporates the temporal as well as spatial lags of spot prices is presented. Joint modeling of space-time effects is necessarily important when prices and loads are determined in a network...
Modelling Parsing Constraints with High-Dimensional Context Space.
Burgess, Curt; Lund, Kevin
1997-01-01
Presents a model of high-dimensional context space, the Hyperspace Analogue to Language (HAL), with a series of simulations modelling human empirical results. Proposes that HAL's context space can be used to provide a basic categorization of semantic and grammatical concepts; model certain aspects of morphological ambiguity in verbs; and provide…
Process Model for Defining Space Sensing and Situational Awareness Requirements
2006-04-01
process model for defining systems for space sensing and space situational awareness is presented. The paper concentrates on eight steps for determining the requirements to include: decision maker needs, system requirements, exploitation methods and vulnerabilities, critical capabilities, and identify attack scenarios. Utilization of the USAF anti-tamper (AT) implementation process as a process model departure point for the space sensing and situational awareness (SSSA...is presented. The AT implementation process model , as an
Shestakova, T P
2013-01-01
We construct Hamiltonian dynamics of the generalized spherically symmetric gravitational model in extended phase space. We start from the Faddeev - Popov effective action with gauge-fixing and ghost terms, making use of gauge conditions in differential form. It enables us to introduce missing velocities into the Lagrangian and then construct a Hamiltonian function according a usual rule which is applied for systems without constraints. The main feature of Hamiltonian dynamics in extended phase space is that it can be proved to be completely equivalent to Lagrangian dynamics derived from the effective action. The sets of Lagrangian and Hamiltonian equations are not gauge invariant in general. We demonstrate that solutions to the obtained equations include those of the gauge invariant Einstein equations, and also discuss a possible role of gauge-noninvariant terms. Then, we find a BRST invariant form of the effective action by adding terms not affecting Lagrangian equations. After all, we construct the BRST cha...
Physical simulation of the long-term dynamic action of a plasma beam on a space debris object
Shuvalov, Valentin A.; Gorev, Nikolai. B.; Tokmak, Nikolai A.; Kochubei, Galina S.
2017-03-01
A methodology is developed for physical (laboratory) simulation of the long-term dynamic action of plasma beam high-energy ions on a space debris object with the aim of removing it to a lower orbit followed by its burning in the Earth's atmosphere. The methodology is based on the use of a criterion for the equivalence of two plasma beam exposure regimes (in the Earth' ionosphere and in laboratory conditions) and an accelerated test procedure in what concerns space debris object material sputtering and space debris object erosion by a plasma beam in the Earth's ionosphere. The space debris coating material (blanket thermal insulation) sputtering yield and normal and tangential momentum transfer coefficients are determined experimentally as a function of the ion energy and the ion beam incidence angle.
Effective action and vacuum expectations in nonlinear $\\sigma$ model
Fayzullaev, B A
2015-01-01
The equations for effective action for nonlinear $\\sigma$ model are derived using DeWitt method in two forms - for generator of vertex parts $\\Gamma$ and for generator of weakly connected parts $W$. Loop-expansion solutions to these equations are found. It is shown that vacuum expectation values for various quantities including divergence of a N\\"{o}ther current, trace of the energy-momentum tensor and so on, can be calculated by this method. Also it is shown that vacuum expectation to the sigma-field is determined by an explicit combination of tree Green function and classical solution. It is shown that the limit when coupling constant tends to zero is singular one.
Determining state-space models from sequential output data
Lin, Jiguan Gene
1988-01-01
This talk focuses on the determination of state-space models for large space systems using only the output data. The output data could be generated by the unknown or deliberate initial conditions of the space structure in question. We shall review some relevant fundamental work on the state-space modeling of sequential output data that is potentially applicable to large space structures. If formulated in terms of some generalized Markov parameters, this approach is in some sense similar to, but much simpler than, the Juang-Pappa Eigensystem Realization Algorithm (ERA) and the Ho-Kalman construction procedure.
Non-commutative Complex Projective Spaces and the Standard Model
Dolan, Brian P
2003-01-01
The standard model fermion spectrum, including a right handed neutrino, can be obtained as a zero-mode of the Dirac operator on a space which is the product of complex projective spaces of complex dimension two and three. The construction requires the introduction of topologically non-trivial background gauge fields. By borrowing from ideas in Connes' non-commutative geometry and making the complex spaces `fuzzy' a matrix approximation to the fuzzy space allows for three generations to emerge...
Gravitational Stability for a Vacuum Cosmic Space Crystalline Model
Montemayor-Aldrete, J A; Morales-Mori, A; Mendoza-Allende, A; Montemayor-Varela, A; Castillo-Mussot, M; Vazquez, G J
2005-01-01
Using Heisenberg's uncertainty principle it is shown that the gravitational stability condition for a crystalline vacuum cosmic space implies to obtain an equation formally equivalent to the relation first used by Gamow to predict the present temperature of the microwave background from the matter density. The compatibility condition between the quantum and the relativistic approaches has been obtained without infinities arising from the quantum analysis or singularities arising from the relativistic theory. The action which leads to our theory is the least action possible in a quantum scheme. The energy fluctuation involved in the gravitational stabilization of vacuum space is 10 to the 40 power times the energy of the crystalline structure of vacuum space inside the present Universe volume. PACS numbers: 04.20.-q, 03.65.-w, 03.50.De, 61.50.-f, 98.80.Ft
A Simulation and Modeling Framework for Space Situational Awareness
Olivier, S.
This paper describes the development and initial demonstration of a new, integrated modeling and simulation framework, encompassing the space situational awareness enterprise, for quantitatively assessing the benefit of specific sensor systems, technologies and data analysis techniques. This framework includes detailed models for threat scenarios, signatures, sensors, observables and knowledge extraction algorithms. The framework is based on a flexible, scalable architecture to enable efficient simulation of the current SSA enterprise, and to accommodate future advancements in SSA systems. In particular, the code is designed to take advantage of massively parallel computer systems available, for example, at Lawrence Livermore National Laboratory. We will describe the details of the modeling and simulation framework, including hydrodynamic models of satellite intercept and debris generation, orbital propagation algorithms, radar cross section calculations, optical and infra-red brightness calculations, generic radar system models, generic optical and infra-red system models, specific Space Surveillance Network models, object detection algorithms, orbit determination algorithms, and visualization tools. The specific modeling of the Space Surveillance Network is performed in collaboration with the Air Force Space Command Space Control Group. We will demonstrate the use of this integrated simulation and modeling framework on specific threat scenarios, including space debris and satellite maneuvers, and we will examine the results of case studies involving the addition of new sensor systems, used in conjunction with the Space Surveillance Network, for improving space situational awareness.
Space-Time Quantization and Nonlocal Field Theory -Relativistic Second Quantization of Matrix Model
Tanaka, S
2000-01-01
We propose relativistic second quantization of matrix model of D particles in a general framework of nonlocal field theory based on Snyder-Yang's quantized space-time. Second-quantized nonlocal field is in general noncommutative with quantized space-time, but conjectured to become commutative with light cone time $X^+$. This conjecture enables us to find second-quantized Hamiltonian of D particle system and Heisenberg's equation of motion of second-quantized {\\bf D} field in close contact with Hamiltonian given in matrix model. We propose Hamilton's principle of Lorentz-invariant action of {\\bf D} field and investigate what conditions or approximations are needed to reproduce the above Heisenberg's equation given in light cone time. Both noncommutativities appearing in position coordinates of D particles in matrix model and in quantized space-time will be eventually unified through second quantization of matrix model.
Dimension invariants for groups admitting a cocompact model for proper actions
DEFF Research Database (Denmark)
Degrijse, Dieter Dries; Martínez-Pérez, Conchita
2016-01-01
Let G be a group that admits a cocompact classifying space for proper actions X. We derive a formula for the Bredon cohomological dimension for proper actions of G in terms of the relative cohomology with compact support of certain pairs of subcomplexes of X. We use this formula to compute the Br...
Primordial gravitational waves from the space-condensate inflation model
Koh, Seoktae; Tumurtushaa, Gansukh
2015-01-01
We consider the space-condensate inflation model to study the primordial gravitational waves generated in the early Universe. We calculate the energy spectrum of gravitational waves induced by the space-condensate inflation model for full frequency range with assumption that the phase transition between two consecutive regimes to be abrupt during evolution of the Universe. The suppression of energy spectrum is found in our model for the decreasing frequency of gravitational waves depending on the model parameter. To realize the suppression of energy spectrum of the primordial gravitational waves, we study an existence of the early phase transition during inflation for the space-condensate inflation model.
Vector space model for document representation in information retrieval
Directory of Open Access Journals (Sweden)
Dan MUNTEANU
2007-12-01
Full Text Available This paper presents the basics of information retrieval: the vector space model for document representation with Boolean and term weighted models, ranking methods based on the cosine factor and evaluation measures: recall, precision and combined measure.
Mixed Models: Combining incompatible scalar models in any space-time dimension
Klauder, John R.
2017-01-01
Traditionally, covariant scalar field theory models are either super renormalizable, strictly renormalizable, or nonrenormalizable. The goal of “Mixed Models” is to make sense of sums of these distinct examples, e.g. gφ34 + g‧φ 36 + g″φ 38, which includes an example of each kind for space-time dimension n = 3. We show how the several interactions such mixed models have may be turned on and off in any order without any difficulties. Analogous results are shown for gφn4 + g‧φ n138, etc. for all n ≥ 3. Different categories hold for n = 2 such as, e.g. gP(φ)2 + g‧NP(φ) 2, that involve polynomial (P) and suitable nonpolynomial (NP) interactions, etc. Analogous situations for n = 1 (time alone) offer simple “toy” examples of how such mixed models may be constructed. As a general rule, if the introduction of a specific interaction term reduces the domain of the free classical action, we invariably find that the introduction of the associated quantum interaction leads, effectively, to a “nonrenormalizable” quantum theory. However, in special cases, a classical interaction that does not reduce the domain of the classical free action may generate an “unsatisfactory” quantum theory, which generally involves a model-specific, different approach to become “satisfactory.” We will encounter both situations in our analysis.
Space Station Freedom electrical performance model
Hojnicki, Jeffrey S.; Green, Robert D.; Kerslake, Thomas W.; Mckissock, David B.; Trudell, Jeffrey J.
1993-01-01
The baseline Space Station Freedom electric power system (EPS) employs photovoltaic (PV) arrays and nickel hydrogen (NiH2) batteries to supply power to housekeeping and user electrical loads via a direct current (dc) distribution system. The EPS was originally designed for an operating life of 30 years through orbital replacement of components. As the design and development of the EPS continues, accurate EPS performance predictions are needed to assess design options, operating scenarios, and resource allocations. To meet these needs, NASA Lewis Research Center (LeRC) has, over a 10 year period, developed SPACE (Station Power Analysis for Capability Evaluation), a computer code designed to predict EPS performance. This paper describes SPACE, its functionality, and its capabilities.
Standardization Process for Space Radiation Models Used for Space System Design
Barth, Janet; Daly, Eamonn; Brautigam, Donald
2005-01-01
The space system design community has three concerns related to models of the radiation belts and plasma: 1) AP-8 and AE-8 models are not adequate for modern applications; 2) Data that have become available since the creation of AP-8 and AE-8 are not being fully exploited for modeling purposes; 3) When new models are produced, there is no authorizing organization identified to evaluate the models or their datasets for accuracy and robustness. This viewgraph presentation provided an overview of the roadmap adopted by the Working Group Meeting on New Standard Radiation Belt and Space Plasma Models.
Modeling Geometric-Temporal Context With Directional Pyramid Co-Occurrence for Action Recognition.
Yuan, Chunfeng; Li, Xi; Hu, Weiming; Ling, Haibin; Maybank, Stephen J
2014-02-01
In this paper, we present a new geometric-temporal representation for visual action recognition based on local spatio-temporal features. First, we propose a modified covariance descriptor under the log-Euclidean Riemannian metric to represent the spatio-temporal cuboids detected in the video sequences. Compared with previously proposed covariance descriptors, our descriptor can be measured and clustered in Euclidian space. Second, to capture the geometric-temporal contextual information, we construct a directional pyramid co-occurrence matrix (DPCM) to describe the spatio-temporal distribution of the vector-quantized local feature descriptors extracted from a video. DPCM characterizes the co-occurrence statistics of local features as well as the spatio-temporal positional relationships among the concurrent features. These statistics provide strong descriptive power for action recognition. To use DPCM for action recognition, we propose a directional pyramid co-occurrence matching kernel to measure the similarity of videos. The proposed method achieves the state-of-the-art performance and improves on the recognition performance of the bag-of-visual-words (BOVWs) models by a large margin on six public data sets. For example, on the KTH data set, it achieves 98.78% accuracy while the BOVW approach only achieves 88.06%. On both Weizmann and UCF CIL data sets, the highest possible accuracy of 100% is achieved.
Partial differential equations in action from modelling to theory
Salsa, Sandro
2016-01-01
The book is intended as an advanced undergraduate or first-year graduate course for students from various disciplines, including applied mathematics, physics and engineering. It has evolved from courses offered on partial differential equations (PDEs) over the last several years at the Politecnico di Milano. These courses had a twofold purpose: on the one hand, to teach students to appreciate the interplay between theory and modeling in problems arising in the applied sciences, and on the other to provide them with a solid theoretical background in numerical methods, such as finite elements. Accordingly, this textbook is divided into two parts. The first part, chapters 2 to 5, is more elementary in nature and focuses on developing and studying basic problems from the macro-areas of diffusion, propagation and transport, waves and vibrations. In turn the second part, chapters 6 to 11, concentrates on the development of Hilbert spaces methods for the variational formulation and the analysis of (mainly) linear bo...
Partial differential equations in action from modelling to theory
Salsa, Sandro
2015-01-01
The book is intended as an advanced undergraduate or first-year graduate course for students from various disciplines, including applied mathematics, physics and engineering. It has evolved from courses offered on partial differential equations (PDEs) over the last several years at the Politecnico di Milano. These courses had a twofold purpose: on the one hand, to teach students to appreciate the interplay between theory and modeling in problems arising in the applied sciences, and on the other to provide them with a solid theoretical background in numerical methods, such as finite elements. Accordingly, this textbook is divided into two parts. The first part, chapters 2 to 5, is more elementary in nature and focuses on developing and studying basic problems from the macro-areas of diffusion, propagation and transport, waves and vibrations. In turn the second part, chapters 6 to 11, concentrates on the development of Hilbert spaces methods for the variational formulation and the analysis of (mainly) linear bo...
Modeling diurnal hormone profiles by hierarchical state space models.
Liu, Ziyue; Guo, Wensheng
2015-10-30
Adrenocorticotropic hormone (ACTH) diurnal patterns contain both smooth circadian rhythms and pulsatile activities. How to evaluate and compare them between different groups is a challenging statistical task. In particular, we are interested in testing (1) whether the smooth ACTH circadian rhythms in chronic fatigue syndrome and fibromyalgia patients differ from those in healthy controls and (2) whether the patterns of pulsatile activities are different. In this paper, a hierarchical state space model is proposed to extract these signals from noisy observations. The smooth circadian rhythms shared by a group of subjects are modeled by periodic smoothing splines. The subject level pulsatile activities are modeled by autoregressive processes. A functional random effect is adopted at the pair level to account for the matched pair design. Parameters are estimated by maximizing the marginal likelihood. Signals are extracted as posterior means. Computationally efficient Kalman filter algorithms are adopted for implementation. Application of the proposed model reveals that the smooth circadian rhythms are similar in the two groups but the pulsatile activities in patients are weaker than those in the healthy controls. Copyright © 2015 John Wiley & Sons, Ltd.
Smooth spaces versus continuous spaces in models for synthetic differential geometry
Reyes, G.E.; Moerdijk, I.
1984-01-01
In topos models for synthetic differential geometry we study connections between smooth spaces (which interpret synthetic calculus) and continuous spaces (which interpret intuitionistic analysis). Our main tools are adjoint retractions of toposes and the standard map from the smooth reals to the con
A Quotient Space Approximation Model of Multiresolution Signal Analysis
Institute of Scientific and Technical Information of China (English)
Ling Zhang; Bo Zhang
2005-01-01
In this paper, we present a quotient space approximation model of multiresolution signal analysis and discuss the properties and characteristics of the model. Then the comparison between wavelet transform and the quotient space approximation is made. First, when wavelet transform is viewed from the new quotient space approximation perspective, it may help us to gain an insight into the essence of multiresolution signal analysis. Second, from the similarity between wavelet and quotient space approximations, it is possible to transfer the rich wavelet techniques into the latter so that a new way for multiresolution analysis may be found.
The Reflective Teacher Leader: An Action Research Model
Furtado, Leena; Anderson, Dawnette
2012-01-01
This study presents four teacher reflections from action research projects ranging from kindergarten to adult school improvements. A teacher leadership matrix guided participants to connect teaching and learning theory to best practices by exploring uncharted territory within an iterative cycle of research and action. Teachers developed the…
Manifestations of Isospin in Nearest Neighbor Spacing Distributions for the f-p Model Space
Quinonez, Michael; Zamick, Larry
2016-01-01
The strong interactions are charge independent. If we limit ourselves to the strong interactions, we have the isospin $T$ as a good quantum number. Here we consider the lack of level repulsion of states of different isospin and how this effect manifests in nearest neighbor spacing (NNS) histograms, which provide a visual and statistical context in which to study distributions of energy level spacings. In particular, we study nucleons in the f-p model space for the nucleus $^{44}$Ti. We also study the effect of the Coulomb interaction on the level spacing distribution.
Kalu, A. E.
A model for Space Weather (SW) Circulation with Plasma Clouds as background radiation medium of Space Environment has been proposed and discussed. Major characteristics of the model are outlined and the model assumes a baroclinic Space Environment in view of observed pronounced horizontal electron temperature gradient with prevailing weak vertical temperature gradient. The primary objective of the study is to be able to monitor and realistically predict on real- or near real-time SW and Space Storms (SWS) affecting human economic systems on Earth as well as the safety and Physiologic comfort of human payload in Space Environment in relation to planned increase in human space flights especially with reference to the ISS Space Shuttle Taxi (ISST) Programme and other prolonged deep Space Missions. Although considerable discussions are now available in the literature on SW issues, routine Meteorological operational applications of SW forecast data and information for Space Environment are still yet to receive adequate attention. The paper attempts to fill this gap in the literature of SW. The paper examines the sensitivity and variability in 3-D continuum of Plasmas in response to solar radiation inputs into the magnetosphere under disturbed Sun condition. Specifically, the presence of plasma clouds in the form of Coronal Mass Ejections (CMEs) is stressed as a major source of danger to Space crews, spacecraft instrumentation and architecture charging problems as well as impacts on numerous radiation - sensitive human economic systems on Earth. Finally, the paper considers the application of model results in the form of effective monitoring of each of the two major phases of manned Spaceflights - take-off and re-entry phases where all-time assessment of spacecraft transient ambient micro-incabin and outside Space Environment is vital for all manned Spaceflights as recently evidenced by the loss of vital information during take-off of the February 1, 2003 US Columbia
Brozzoli, Claudio; Ehrsson, H Henrik; Farnè, Alessandro
2014-04-01
When interacting with objects and other people, the brain needs to locate our limbs and the relevant visual information surrounding them. Studies on monkeys showed that information from different sensory modalities converge at the single cell level within a set of interconnected multisensory frontoparietal areas. It is largely accepted that this network allows for multisensory processing of the space surrounding the body (peripersonal space), whose function has been linked to the sensory guidance of appetitive and defensive movements, and localization of the limbs in space. In the current review, we consider multidisciplinary findings about the processing of the space near the hands in humans and offer a convergent view of its functions and underlying neural mechanisms. We will suggest that evolution has provided the brain with a clever tool for representing visual information around the hand, which takes the hand itself as a reference for the coding of surrounding visual space. We will contend that the hand-centered representation of space, known as perihand space, is a multisensory-motor interface that allows interaction with the objects and other persons around us.
Action-space clustering of tidal streams to infer the Galactic potential
Sanderson, Robyn E; Hogg, David W
2014-01-01
We present a new method for constraining the Milky Way halo gravitational potential by simultaneously fitting multiple tidal streams. This method requires full three-dimensional positions and velocities for all stars in the streams, but does not require identification of any specific stream, nor determination of stream membership for any star. We exploit the principle that the action distribution of stream stars is most clustered---that is, most informative---when the potential used to calculate the actions is closest to the true potential. We measure the amount of clustering with the Kullback-Leibler Divergence (KLD) or relative entropy, a statistical measure of information which also provides uncertainties for our parameter estimates. We show, for toy Gaia-like data in a spherical isochrone potential, that maximizing the KLD of the action distribution relative to a smoother distribution recovers the true values of the potential parameters. The precision depends on the observational errors and the number and...
Classification of gradient space of dimension 8 by a reducible sl(2,C)action
Institute of Scientific and Technical Information of China (English)
YAU; Stephen; S.-T.
2009-01-01
This paper deals with a reducible sl(2,C)action on the formal power series ring.The purpose of this paper is to confirm a special case of the Yau conjecture:Suppose that sl(2,C)acts on the formal power series ring via(1.1).Then I(f)=(li 1 )⊕(il2 )⊕···⊕(lis)modulo some one dimensional sl(2,C)representations where(i)is an irreducible sl(2,C)representation of i dimension and{li1 ,li2 ,...,lis }{ll1,ll2,...,lr}.Unlike classical invariant theory which deals only with irreducible action and 1-dimensional representations,we treat the reducible action and higher dimensional representations successively.
Green space system design in Luoyang using Huff model
Wang, Shengnan; Li, Meng
2008-10-01
Green space system, as part of the urban ecological environment and urban landscape, plays a significant role in the protection of biological diversity of the urban eco-systems. During the process of rapid modernization in China, it is evident that in order to satisfy the residents' needs of entertainment and communication effectively; there should be abundant types and adequate arrangement of green space. And at the same time a comprehensive and stable hierarchical structure of green space system ought to be established. Huff Model is widely used in facility location planning and service area segmentation in business geography, and has potentials in urban facility planning and design. This paper aims to evaluate, design and optimize the urban green space in Luoyang City, Henan Province, using GIS and Huff Model. Considering the existing location, size and shape of the green space supply, the spatial distribution of residence and the urban transportation systems, the attractiveness between residence and green space is estimated. The spatial pattern and service capability of the green space system are also evaluated critically. Based on the findings, the possible optimization design of the green space system in Luoyang is discussed innovatively. Huff model test shows that the design improves the overall spatial accessibility observably. The case study shows that GIS technology and Huff Model have great potential in urban green space evaluation, planning and design.
Development, validation and application of numerical space environment models
Honkonen, Ilja
2013-10-01
Currently the majority of space-based assets are located inside the Earth's magnetosphere where they must endure the effects of the near-Earth space environment, i.e. space weather, which is driven by the supersonic flow of plasma from the Sun. Space weather refers to the day-to-day changes in the temperature, magnetic field and other parameters of the near-Earth space, similarly to ordinary weather which refers to changes in the atmosphere above ground level. Space weather can also cause adverse effects on the ground, for example, by inducing large direct currents in power transmission systems. The performance of computers has been growing exponentially for many decades and as a result the importance of numerical modeling in science has also increased rapidly. Numerical modeling is especially important in space plasma physics because there are no in-situ observations of space plasmas outside of the heliosphere and it is not feasible to study all aspects of space plasmas in a terrestrial laboratory. With the increasing number of computational cores in supercomputers, the parallel performance of numerical models on distributed memory hardware is also becoming crucial. This thesis consists of an introduction, four peer reviewed articles and describes the process of developing numerical space environment/weather models and the use of such models to study the near-Earth space. A complete model development chain is presented starting from initial planning and design to distributed memory parallelization and optimization, and finally testing, verification and validation of numerical models. A grid library that provides good parallel scalability on distributed memory hardware and several novel features, the distributed cartesian cell-refinable grid (DCCRG), is designed and developed. DCCRG is presently used in two numerical space weather models being developed at the Finnish Meteorological Institute. The first global magnetospheric test particle simulation based on the
Renewed Support Dawns in Europe: An Action to Develop Space Weather Products and Services
Belehaki, Anna; Watermann, Jurgen; Lilensten, Jean; Glover, Alexi; Hapgood, Mike; Messerotti, Mauro; van der Linden, Ronald; Lundstedt, Henrik
2009-03-01
The effects of space weather span a range of sectors. They can cause radio communications problems; can disrupt synthetic aperture radar systems, the Global Positioning System (GPS), and the future European Galileo systems; and can increase radiation risks for aircraft crew and passengers. Electric power network disturbances and enhanced corrosion effects observed in long-distance fuel supply pipelines are other well-known effects of unfavorable space weather. In severe cases, large-scale power outages have also been traced to space weather phenomena (Figure 1).
Saab, Rim; Tausch, Nicole; Spears, Russell; Cheung, Wing-Yee
2015-01-01
We examined predictors of collective action among bystander group members in solidarity with a disadvantaged group by extending the dual pathway model of collective action, which proposes one efficacy-based and one emotion-based path to collective action (Van Zomeren, Spears, Fischer, & Leach, 2004)
Energy Spectrum Symmetry of Heisenberg Model in Fock Space
Institute of Scientific and Technical Information of China (English)
WANG An-Min; ZHU Ren-Gui
2006-01-01
@@ We extend the BCS paring model with equally spaced energy levels to a general one-dimensional spin-l/2 Heisenberg model. The two well-known symmetries of the Heisenberg model, i.e. permutational and spin-inversion symmetries, no longer exist. However, when jointing these two operations together, we find a new symmetry of energy spectrum between its subspace n and subspace L - n of the Fock space. A rigorous proof is presented.
Combining search space partition and search Space partition and abstraction for LTL model checking
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The state space explosion problem is still the key obstacle for applying model checking to systems of industrial size.Abstraction-based methods have been particularly successful in this regard.This paper presents an approach based on refinement of search space partition and abstraction which combines these two techniques for reducing the complexity of model checking.The refinement depends on the representation of each portion of search space. Especially, search space can be refined stepwise to get a better reduction. As reported in the case study, the Integration of search space partition and abstraction improves the efficiencyof verification with respect to the requirement of memory and obtains significant advantage over the use of each of them in isolation.
Sato, Marc; Vilain, Coriandre; Lamalle, Laurent; Grabski, Krystyna
2015-02-01
Studies of speech motor control suggest that articulatory and phonemic goals are defined in multidimensional motor, somatosensory, and auditory spaces. To test whether motor simulation might rely on sensory-motor coding common with those for motor execution, we used a repetition suppression (RS) paradigm while measuring neural activity with sparse sampling fMRI during repeated overt and covert orofacial and speech actions. RS refers to the phenomenon that repeated stimuli or motor acts lead to decreased activity in specific neural populations and are associated with enhanced adaptive learning related to the repeated stimulus attributes. Common suppressed neural responses were observed in motor and posterior parietal regions in the achievement of both repeated overt and covert orofacial and speech actions, including the left premotor cortex and inferior frontal gyrus, the superior parietal cortex and adjacent intraprietal sulcus, and the left IC and the SMA. Interestingly, reduced activity of the auditory cortex was observed during overt but not covert speech production, a finding likely reflecting a motor rather an auditory imagery strategy by the participants. By providing evidence for adaptive changes in premotor and associative somatosensory brain areas, the observed RS suggests online state coding of both orofacial and speech actions in somatosensory and motor spaces with and without motor behavior and sensory feedback.
A FORMAL SPECIFICATION LANGUAGE FOR DYNAMIC STRAND SPACE MODEL
Institute of Scientific and Technical Information of China (English)
刘东喜; 李晓勇; 白英彩
2002-01-01
Specification language is used to provide enough information for the model of the cryptographic protocol. This paper first extends strand space model to dynamic strand model, and then a formal specification language for this model is defined by using BNF grammar. Compared with those in literatures, it is simpler because of only concerning the algebraic properties of cryptographic protocols.
Space Mapping Optimization of Microwave Circuits Exploiting Surrogate Models
DEFF Research Database (Denmark)
Bakr, M. H.; Bandler, J. W.; Madsen, Kaj
2000-01-01
A powerful new space-mapping (SM) optimization algorithm is presented in this paper. It draws upon recent developments in both surrogate model-based optimization and modeling of microwave devices, SM optimization is formulated as a general optimization problem of a surrogate model. This model...
Library Spaces for Urban, Diverse Commuter Students: A Participatory Action Research Project
Brown-Sica, Margaret S.
2012-01-01
A data-gathering project using elements of Participatory Action Research was conducted at the Auraria Library, which serves the University of Colorado Denver, the Metropolitan State College of Denver and the Community College of Denver. The project was administered in order to shape a plan to develop a Learning Commons environment at the library.…
On the existence of star products on quotient spaces of linear Hamiltonian torus actions
DEFF Research Database (Denmark)
Herbig, Hans-Christian; Iyengar, Srikanth B.; Pflaum, Markus J.
2009-01-01
We discuss BFV deformation quantization (Bordemann et al. in A homological approach to singular reduction in deformation quantization, singularity theory, pp. 443–461. World Scientific, Hackensack, 2007) in the special case of a linear Hamiltonian torus action. In particular, we show that the Kos...
Library Spaces for Urban, Diverse Commuter Students: A Participatory Action Research Project
Brown-Sica, Margaret S.
2012-01-01
A data-gathering project using elements of Participatory Action Research was conducted at the Auraria Library, which serves the University of Colorado Denver, the Metropolitan State College of Denver and the Community College of Denver. The project was administered in order to shape a plan to develop a Learning Commons environment at the library.…
Kuznetsova, Maria
The Community Coordinated Modeling Center (CCMC, http://ccmc.gsfc.nasa.gov) was established at the dawn of the new millennium as a long-term flexible solution to the problem of transition of progress in space environment modeling to operational space weather forecasting. CCMC hosts an expanding collection of state-of-the-art space weather models developed by the international space science community. Over the years the CCMC acquired the unique experience in preparing complex models and model chains for operational environment and developing and maintaining custom displays and powerful web-based systems and tools ready to be used by researchers, space weather service providers and decision makers. In support of space weather needs of NASA users CCMC is developing highly-tailored applications and services that target specific orbits or locations in space and partnering with NASA mission specialists on linking CCMC space environment modeling with impacts on biological and technological systems in space. Confidence assessment of model predictions is an essential element of space environment modeling. CCMC facilitates interaction between model owners and users in defining physical parameters and metrics formats relevant to specific applications and leads community efforts to quantify models ability to simulate and predict space environment events. Interactive on-line model validation systems developed at CCMC make validation a seamless part of model development circle. The talk will showcase innovative solutions for space weather research, validation, anomaly analysis and forecasting and review on-going community-wide model validation initiatives enabled by CCMC applications.
Modeling the long-term evolution of space debris
Nikolaev, Sergei; De Vries, Willem H.; Henderson, John R.; Horsley, Matthew A.; Jiang, Ming; Levatin, Joanne L.; Olivier, Scot S.; Pertica, Alexander J.; Phillion, Donald W.; Springer, Harry K.
2017-03-07
A space object modeling system that models the evolution of space debris is provided. The modeling system simulates interaction of space objects at simulation times throughout a simulation period. The modeling system includes a propagator that calculates the position of each object at each simulation time based on orbital parameters. The modeling system also includes a collision detector that, for each pair of objects at each simulation time, performs a collision analysis. When the distance between objects satisfies a conjunction criterion, the modeling system calculates a local minimum distance between the pair of objects based on a curve fitting to identify a time of closest approach at the simulation times and calculating the position of the objects at the identified time. When the local minimum distance satisfies a collision criterion, the modeling system models the debris created by the collision of the pair of objects.
Modeling the long-term evolution of space debris
Energy Technology Data Exchange (ETDEWEB)
Nikolaev, Sergei; De Vries, Willem H.; Henderson, John R.; Horsley, Matthew A.; Jiang, Ming; Levatin, Joanne L.; Olivier, Scot S.; Pertica, Alexander J.; Phillion, Donald W.; Springer, Harry K.
2017-03-07
A space object modeling system that models the evolution of space debris is provided. The modeling system simulates interaction of space objects at simulation times throughout a simulation period. The modeling system includes a propagator that calculates the position of each object at each simulation time based on orbital parameters. The modeling system also includes a collision detector that, for each pair of objects at each simulation time, performs a collision analysis. When the distance between objects satisfies a conjunction criterion, the modeling system calculates a local minimum distance between the pair of objects based on a curve fitting to identify a time of closest approach at the simulation times and calculating the position of the objects at the identified time. When the local minimum distance satisfies a collision criterion, the modeling system models the debris created by the collision of the pair of objects.
A Learning State-Space Model for Image Retrieval
Directory of Open Access Journals (Sweden)
Lee Greg C
2007-01-01
Full Text Available This paper proposes an approach based on a state-space model for learning the user concepts in image retrieval. We first design a scheme of region-based image representation based on concept units, which are integrated with different types of feature spaces and with different region scales of image segmentation. The design of the concept units aims at describing similar characteristics at a certain perspective among relevant images. We present the details of our proposed approach based on a state-space model for interactive image retrieval, including likelihood and transition models, and we also describe some experiments that show the efficacy of our proposed model. This work demonstrates the feasibility of using a state-space model to estimate the user intuition in image retrieval.
Properties of Brownian Image Models in Scale-Space
DEFF Research Database (Denmark)
Pedersen, Kim Steenstrup
2003-01-01
In this paper it is argued that the Brownian image model is the least committed, scale invariant, statistical image model which describes the second order statistics of natural images. Various properties of three different types of Gaussian image models (white noise, Brownian and fractional...... Brownian images) will be discussed in relation to linear scale-space theory, and it will be shown empirically that the second order statistics of natural images mapped into jet space may, within some scale interval, be modeled by the Brownian image model. This is consistent with the 1/f 2 power spectrum...... law that apparently governs natural images. Furthermore, the distribution of Brownian images mapped into jet space is Gaussian and an analytical expression can be derived for the covariance matrix of Brownian images in jet space. This matrix is also a good approximation of the covariance matrix...
Simulation Modeling of Space Missions Using the High Level Architecture
Directory of Open Access Journals (Sweden)
Luis Rabelo
2013-01-01
Full Text Available This paper discusses an environment being developed to model a mission of the Space Launch System (SLS and the Multipurpose Crew Vehicle (MPCV being launched from Kennedy Space Center (KSC to the International Space Station (ISS. Several models representing different phases of the mission such as the ground operations processes, engineered systems, and range components such as failure tree, blast, gas dispersion, and debris modeling are explained. These models are built using different simulation paradigms such as continuous, system dynamics, discrete-event, and agent-based simulation modeling. The High Level Architecture (HLA is the backbone of this distributed simulation. The different design decisions and the information fusion scheme of this unique environment are explained in detail for decision-making. This can also help in the development of exploration missions beyond the International Space Station.
Computerised analysis of sulphate action on model concrete piles
Digital Repository Service at National Institute of Oceanography (India)
Deshmukh, A.M.; Balasubramanian, S.; Venugopal, C.
Sulphate action severely affects the durability of marine structures. It is imperative to study precisely the effects of magnesium sulphate on pile foundations in the marine environment. In the present paper an attempt is made to assess and analyse...
Quantum-Dot Semiconductor Optical Amplifiers: State Space Model versus Rate Equation Model
Directory of Open Access Journals (Sweden)
Hussein Taleb
2013-01-01
Full Text Available A simple and accurate dynamic model for QD-SOAs is proposed. The proposed model is based on the state space theory, where by eliminating the distance dependence of the rate equation model of the QD-SOA; we derive a state space model for the device. A comparison is made between the rate equation model and the state space model under both steady state and transient regimes. Simulation results demonstrate that the derived state space model not only is much simpler and faster than the rate equation model, but also it is as accurate as the rate equation model.
Thermomechanical modelling of ground response under environmental actions.
Samat, Sergio
2016-01-01
Natural disasters, such as landslides triggered by heavy rains, rock deformations and soil cracking in presence of temperature changes and other phenomena related to climatic actions, show the relevance of investigating the effects of the interactions between the atmosphere and the earth ground surface where main human activities develop. The prediction of such hazard requires an adequate knowledge of the changes in hydro-geological conditions under climatic actions. Having advanced constitut...
THE USE OF MODELS IN URBAN SPACE PATTERN ANALYSIS ...
African Journals Online (AJOL)
spaces of a modest size is the Figure - Ground relationship or ... (Note the dominance of unstructured open spaces in the City Centre) ordering of ..... their rank. This settlement typology is the formative model of most towns founded by emperors ...
Modeling Spaces for Self-Directed Learning at University Courses
Pata, Kai
2009-01-01
This paper conceptualizes the theoretical framework of modeling learning spaces for self-directed learning at university courses. It binds together two ideas: (a) self-directed learners' common learning spaces may be characterized as abstract niches, (b) niche characteristics are collectively determined through individually perceived affordances.…
Action Algebras and Model Algebras in Denotational Semantics
Guedes, Luiz Carlos Castro; Haeusler, Edward Hermann
the same way as that for functional denotational types. For example, PASCAL arrays belong to the “language inherent” aspect, while the Store domain seems to belong to the “model dependent” aspect. This distinction was important because it focussed attention on optimizing the model dependent semantic domains to obtain a more efficient implementation.) The research led to a nice conclusion: The guidelines of Action Semantics induce a clear separation of the model and language inherent aspects of a language’s semantics. A good implementation of facets, particularly the model dependent ones, leads to generation of an efficient compiler. In this article we discuss the separation of the language inherent and model-inherent domains at the theoretical and conceptual level. In doing so, the authors hope to show how Professor Mosses’s influence extended beyond his technical advice to his professional and personal examples on the supervision of PhD research.
One-loop structure of the U(1) gauge model on the truncated Heisenberg space
Burić, Maja; Nenadović, Luka; Prekrat, Dragan
2016-12-01
We calculate divergent one-loop corrections to the propagators of the U(1) gauge theory on the truncated Heisenberg space, which is one of the extensions of the Grosse-Wulkenhaar model. The model is purely geometric, based on the Yang-Mills action; the corresponding gauge-fixed theory is BRST invariant. We quantize perturbatively and, along with the usual wave-function and mass renormalizations, we find divergent nonlocal terms of the Box ^{-1} and Box ^{-2} type. We discuss the meaning of these terms and possible improvements of the model.
One-loop structure of the U(1) gauge model on the truncated Heisenberg space
Burić, Maja; Prekrat, Dragan
2016-01-01
We calculate divergent one-loop corrections to the propagators of the U(1) gauge theory on the truncated Heisenberg space, which is one of the extensions of the Grosse-Wulkenhaar model. The model is purely geometric, based on the Yang-Mills action; the corresponding gauge-fixed theory is BRST invariant. We quantize perturbatively and, along with the usual wave-function and mass renormalizations, we find divergent nonlocal terms of the $\\Box^{-1}$ and $\\Box^{-2}$ type. We discuss the meaning of these terms and possible improvements of the model.
A Simulation and Modeling Framework for Space Situational Awareness
Energy Technology Data Exchange (ETDEWEB)
Olivier, S S
2008-09-15
This paper describes the development and initial demonstration of a new, integrated modeling and simulation framework, encompassing the space situational awareness enterprise, for quantitatively assessing the benefit of specific sensor systems, technologies and data analysis techniques. The framework is based on a flexible, scalable architecture to enable efficient, physics-based simulation of the current SSA enterprise, and to accommodate future advancements in SSA systems. In particular, the code is designed to take advantage of massively parallel computer systems available, for example, at Lawrence Livermore National Laboratory. The details of the modeling and simulation framework are described, including hydrodynamic models of satellite intercept and debris generation, orbital propagation algorithms, radar cross section calculations, optical brightness calculations, generic radar system models, generic optical system models, specific Space Surveillance Network models, object detection algorithms, orbit determination algorithms, and visualization tools. The use of this integrated simulation and modeling framework on a specific scenario involving space debris is demonstrated.
Integrability of geodesics and action-angle variables in Sasaki-Einstein space T{sup 1,1}
Energy Technology Data Exchange (ETDEWEB)
Visinescu, Mihai [National Institute of Physics and Nuclear Engineering, Department Theoretical Physics, Magurele, Bucharest (Romania)
2016-09-15
We briefly describe the construction of Staekel-Killing and Killing-Yano tensors on toric Sasaki-Einstein manifolds without working out intricate generalized Killing equations. The integrals of geodesic motions are expressed in terms of Killing vectors and Killing-Yano tensors of the homogeneous Sasaki-Einstein space T{sup 1,1}. We discuss the integrability of geodesics and construct explicitly the action-angle variables. Two pairs of frequencies of the geodesic motions are resonant giving way to chaotic behavior when the system is perturbed. (orig.)
Space ecoliteracy- five informal education models for community empowerment
Venkataramaiah, Jagannatha; Jagannath, Sahana; J, Spandana; J, Sadhana; Jagannath, Shobha
Space ecoliteracy is a historical necessity and vital aspect of space age.Space Situational Awareness has taught lessons for mankind to look inward while stretching beyond cradle in human endeavours. Quality of life for every one on the only home of mankind-TERRA shall be a feasibility only after realizing Space ecoliteracy amongst all stakeholders in space quest. Objectives of Informal Environmental Education(UNESCO/UNEP/IEEP,1977) mandates awareness, attitude, knowledge, skill and participation at Individual and Community domains. Application of Space Technology at both Telecommunications and Remote Sensing domain have started making the fact that mankind has a challenge to learn and affirm earthmanship. Community empowerment focus after Earth Summit 1992 mandate of Sustainable Development has demonstrated a deluge of best practices in Agriculture,Urban, Industries and service sectors all over the globe. Further, deployment of Space technologies have proved the immense potential only after pre-empting the participatory approach at individual and community levels.Indian Space Programme with its 44th year of space service to national development has demonstrated self reliance in space technology for human development. Space technology for the most underdeveloped is a success story both in communication and information tools for quality of life. In this presentation Five Space Ecoliteracy models designed and validated since 1985 till date on informal environmental education namely 1) Ecological Environmental Studies by Students-EESS (1988): cited as one of the 20 best eco -education models by Earth Day Network,2)Community Eco Literacy Campaign-CEL,(2000): cited as a partner under Clean Up the World Campaign,UN, 3) Space Eco Literacy(2011)-an informa 8 week space eco literacy training reported at 39th COSPAR 12 assembly and 4) Space Eco Literacy by Practice(2014)- interface with formal education at institutions and 5) Space Ecoliteracy Mission as a space out reach in
Pilot-Wave Quantum Theory in Discrete Space and Time and the Principle of Least Action
Gluza, Janusz; Kosek, Jerzy
2016-11-01
The idea of obtaining a pilot-wave quantum theory on a lattice with discrete time is presented. The motion of quantum particles is described by a |Ψ |^2-distributed Markov chain. Stochastic matrices of the process are found by the discrete version of the least-action principle. Probability currents are the consequence of Hamilton's principle and the stochasticity of the Markov process is minimized. As an example, stochastic motion of single particles in a double-slit experiment is examined.
Nonlinear Sigma Models with Compact Hyperbolic Target Spaces
Gubser, Steven; Schoenholz, Samuel S; Stoica, Bogdan; Stokes, James
2015-01-01
We explore the phase structure of nonlinear sigma models with target spaces corresponding to compact quotients of hyperbolic space, focusing on the case of a hyperbolic genus-2 Riemann surface. The continuum theory of these models can be approximated by a lattice spin system which we simulate using Monte Carlo methods. The target space possesses interesting geometric and topological properties which are reflected in novel features of the sigma model. In particular, we observe a topological phase transition at a critical temperature, above which vortices proliferate, reminiscent of the Kosterlitz-Thouless phase transition in the $O(2)$ model. Unlike in the $O(2)$ case, there are many different types of vortices, suggesting a possible analogy to the Hagedorn treatment of statistical mechanics of a proliferating number of hadron species. Below the critical temperature the spins cluster around six special points in the target space known as Weierstrass points. The diversity of compact hyperbolic manifolds suggest...
mathematical model for direct evaporative space cooling systems
African Journals Online (AJOL)
eobe
MATHEMATICAL MODEL FOR DIRECT EVAPORATIVE SPACE COOLING. SYSTEMS ... Water is the working fluid in evaporative cooling thus it is ..... co o lin g efficien cy (%. ) Time (hrs) predicted experimental. 0. 10. 20. 30. 40. 50. 60. 70. 80.
Hacyan, Shahen
2006-11-01
Since the famous Einstein-Podolsky-Rosen (EPR) paper, it is clear that there is a serious incompatibility between local realism and quantum mechanics. Einstein believed that a complete quantum theory should be free of what he once called "spooky actions at distance". However, all experiments in quantum optics and atomic physics performed in the last two decades confirm the existence of quantum correlations that seem to contradict local realism. According to Bohr, the apparent contradictions disclose only the inadequacy of our customary concepts for the description of the quantum world. Are space and time such customary concepts? In this presentation, I argue that the Copenhagen interpretation is compatible with Kant's transcendental idealism and that, in particular, EPR type paradoxes are consistent with Kant's transcendental aesthetics, according to which space and time have no objective reality but are pure forms of sensible intuition.
Parametric study of the Noble's action potential model for cardiac Purkinje fibers
Energy Technology Data Exchange (ETDEWEB)
Wang, P.K.C. [Department of Electrical Engineering, University of California, Los Angeles, CA 90095-1594 (United States); Kogan, B.Y. [Department of Computer Science, University of California, Los Angeles, CA 90095-1594 (United States)]. E-mail: kogan@cs.ucla.edu
2007-08-15
The effect of parameter variation on repolarization processes in the Noble model (Hodjkin-Huxley type) for action potential (AP) generation in Purkinje cells is studied using a combination of computer simulation and nonlinear dynamic system theory including Hopf bifurcation analysis. Both the original Noble model and a simplified Noble model are used in this study. It is shown that these models have similar qualitative dynamic behavior in the presence of parameter variations. In particular, it is demonstrated that both normal and abnormal modes of cell performance can be obtained by varying the potassium and anion conductances. The abnormal mode (cardiac arrest) may play a significant role in disorganizing the electrical activities in the heart muscles. The existence of Hopf bifurcation with respect to variations in the anion conductance and fixed values of potassium conductances is studied in detail. The regions corresponding to spontaneous AP excitation, and various types of cardiac arrest in the ion-conductance parameter space of both full and simplified Noble models with and without external stimuli are mapped out using computer simulation.
Statistical modeling of space shuttle environmental data
Tubbs, J. D.; Brewer, D. W.
1983-01-01
Statistical models which use a class of bivariate gamma distribution are examined. Topics discussed include: (1) the ratio of positively correlated gamma varieties; (2) a method to determine if unequal shape parameters are necessary in bivariate gamma distribution; (3) differential equations for modal location of a family of bivariate gamma distribution; and (4) analysis of some wind gust data using the analytical results developed for modeling application.
A Situative Space Model for Mobile Mixed-Reality Computing
DEFF Research Database (Denmark)
Pederson, Thomas; Janlert, Lars-Erik; Surie, Dipak
2011-01-01
This article proposes a situative space model that links the physical and virtual realms and sets the stage for complex human-computer interaction defined by what a human agent can see, hear, and touch, at any given point in time.......This article proposes a situative space model that links the physical and virtual realms and sets the stage for complex human-computer interaction defined by what a human agent can see, hear, and touch, at any given point in time....
2008-01-01
This audit was initiated in response to a hotline complaint regarding the review, approval, and release of scientific and technical information (STI) at Johnson Space Center. The complainant alleged that Johnson personnel conducting export control reviews of STI were not fully qualified to conduct those reviews and that the reviews often did not occur until after the STI had been publicly released. NASA guidance requires that STI, defined as the results of basic and applied scientific, technical, and related engineering research and development, undergo certain reviews prior to being released outside of NASA or to audiences that include foreign nationals. The process includes technical, national security, export control, copyright, and trade secret (e.g., proprietary data) reviews. The review process was designed to preclude the inappropriate dissemination of sensitive information while ensuring that NASA complies with a requirement of the National Aeronautics and Space Act of 1958 (the Space Act)1 to provide for the widest practicable and appropriate dissemination of information resulting from NASA research activities. We focused our audit on evaluating the STI review process: specifically, determining whether the roles and responsibilities for the review, approval, and release of STI were adequately defined and documented in NASA and Center-level guidance and whether that guidance was effectively implemented at Goddard Space Flight Center, Johnson Space Center, Langley Research Center, and Marshall Space Flight Center. Johnson was included in the review because it was the source of the initial complaint, and Goddard, Langley, and Marshall were included because those Centers consistently produce significant amounts of STI.
2008-01-01
This audit was initiated in response to a hotline complaint regarding the review, approval, and release of scientific and technical information (STI) at Johnson Space Center. The complainant alleged that Johnson personnel conducting export control reviews of STI were not fully qualified to conduct those reviews and that the reviews often did not occur until after the STI had been publicly released. NASA guidance requires that STI, defined as the results of basic and applied scientific, technical, and related engineering research and development, undergo certain reviews prior to being released outside of NASA or to audiences that include foreign nationals. The process includes technical, national security, export control, copyright, and trade secret (e.g., proprietary data) reviews. The review process was designed to preclude the inappropriate dissemination of sensitive information while ensuring that NASA complies with a requirement of the National Aeronautics and Space Act of 1958 (the Space Act)1 to provide for the widest practicable and appropriate dissemination of information resulting from NASA research activities. We focused our audit on evaluating the STI review process: specifically, determining whether the roles and responsibilities for the review, approval, and release of STI were adequately defined and documented in NASA and Center-level guidance and whether that guidance was effectively implemented at Goddard Space Flight Center, Johnson Space Center, Langley Research Center, and Marshall Space Flight Center. Johnson was included in the review because it was the source of the initial complaint, and Goddard, Langley, and Marshall were included because those Centers consistently produce significant amounts of STI.
Space engineering modeling and optimization with case studies
Pintér, János
2016-01-01
This book presents a selection of advanced case studies that cover a substantial range of issues and real-world challenges and applications in space engineering. Vital mathematical modeling, optimization methodologies and numerical solution aspects of each application case study are presented in detail, with discussions of a range of advanced model development and solution techniques and tools. Space engineering challenges are discussed in the following contexts: •Advanced Space Vehicle Design •Computation of Optimal Low Thrust Transfers •Indirect Optimization of Spacecraft Trajectories •Resource-Constrained Scheduling, •Packing Problems in Space •Design of Complex Interplanetary Trajectories •Satellite Constellation Image Acquisition •Re-entry Test Vehicle Configuration Selection •Collision Risk Assessment on Perturbed Orbits •Optimal Robust Design of Hybrid Rocket Engines •Nonlinear Regression Analysis in Space Engineering< •Regression-Based Sensitivity Analysis and Robust Design ...
Hypersurface-deformation algebroids and effective space-time models
Bojowald, Martin; Buyukcam, Umut; D'Ambrosio, Fabio
2016-01-01
In canonical gravity, covariance is implemented by brackets of hypersurface-deformation generators forming a Lie algebroid. Lie algebroid morphisms therefore allow one to relate different versions of the brackets that correspond to the same space-time structure. An application to examples of modified brackets found mainly in models of loop quantum gravity can in some cases map the space-time structure back to the classical Riemannian form after a field redefinition. For one type of quantum corrections (holonomies), signature change appears to be a generic feature of effective space-time, and is shown here to be a new quantum space-time phenomenon which cannot be mapped to an equivalent classical structure. In low-curvature regimes, our constructions prove the existence of classical space-time structures assumed elsewhere in models of loop quantum cosmology, but also shows the existence of additional quantum corrections that have not always been included.
Modeling thermally active building components using space mapping
DEFF Research Database (Denmark)
Pedersen, Frank; Weitzmann, Peter; Svendsen, Svend
2005-01-01
simplified models of the components do not always provide useful solutions, since they are not always able to reproduce the correct thermal behavior. The space mapping technique transforms a simplified, but computationally inexpensive model, in order to align it with a detailed model or measurements....... This paper describes the principle of the space mapping technique, and introduces a simple space mapping technique. The technique is applied to a lumped parameter model of a thermo active component, which provides a model of the thermal performance of the component as a function of two design parameters......In order to efficiently implement thermally active building components in new buildings, it is necessary to evaluate the thermal interaction between them and other building components. Applying parameter investigation or numerical optimization methods to a differential-algebraic (DAE) model...
Vanlommel, Petra; Messerotti, Mauro; Lilensten, Jean; Calders, Stijn; Bonte, Katrien; D'Huys, Elke; Žigman, Vida
2014-01-01
COST (European Cooperation in Science and Technology) is one of the longest-running European frameworks supporting cooperation among scientists and researchers across Europe. Its action ES0803 "Developing Space Weather Products and Services in Europe" involves the task "Exploitation, Dissemination, Education and Outreach". To meet the objectives of this task, we describe how we developed and maintained the Space Weather Portal, initiated the electronic Journal of Space Weather and Space Climate, took care of the scientific organization of the annual European Space Weather Week conference and of two schools for scientists and students from the space weather community. We also describe several dissemination projects supported by the action, which target the non-specialist in the field of space weather.
ACTION-SPACE CLUSTERING OF TIDAL STREAMS TO INFER THE GALACTIC POTENTIAL
Energy Technology Data Exchange (ETDEWEB)
Sanderson, Robyn E.; Helmi, Amina [Kapteyn Astronomical Institute, P.O. Box 800, 9700 AV Groningen (Netherlands); Hogg, David W., E-mail: robyn@astro.columbia.edu [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States)
2015-03-10
We present a new method for constraining the Milky Way halo gravitational potential by simultaneously fitting multiple tidal streams. This method requires three-dimensional positions and velocities for all stars to be fit, but does not require identification of any specific stream or determination of stream membership for any star. We exploit the principle that the action distribution of stream stars is most clustered when the potential used to calculate the actions is closest to the true potential. Clustering is quantified with the Kullback-Leibler Divergence (KLD), which also provides conditional uncertainties for our parameter estimates. We show, for toy Gaia-like data in a spherical isochrone potential, that maximizing the KLD of the action distribution relative to a smoother distribution recovers the input potential. The precision depends on the observational errors and number of streams; using K III giants as tracers, we measure the enclosed mass at the average radius of the sample stars accurate to 3% and precise to 20%-40%. Recovery of the scale radius is precise to 25%, biased 50% high by the small galactocentric distance range of stars in our mock sample (1-25 kpc, or about three scale radii, with mean 6.5 kpc). 20-25 streams with at least 100 stars each are required for a stable confidence interval. With radial velocities (RVs) to 100 kpc, all parameters are determined with ∼10% accuracy and 20% precision (1.3% accuracy for the enclosed mass), underlining the need to complete the RV catalog for faint halo stars observed by Gaia.
Diffusion Resonances in Action Space for an Atom Optics Kicked Rotor with Decoherence
Daley, A J; Leonhardt, R; Tan, S M
2001-01-01
We numerically investigate momentum diffusion rates for the pulse kicked rotor across the quantum to classical transition as the dynamics are made more macroscopic by increasing the total system action. For initial and late time rates we observe an enhanced diffusion peak which shifts and scales with changing kick strength, and we also observe distinctive peaks around quantum resonances. Our investigations take place in the context of a system of ultracold atoms which is coupled to its environment via spontaneous emission decoherence, and the effects should be realisable in ongoing experiments.
Validation of ecological state space models using the Laplace approximation
DEFF Research Database (Denmark)
Thygesen, Uffe Høgsbro; Albertsen, Christoffer Moesgaard; Berg, Casper Willestofte
2017-01-01
Many statistical models in ecology follow the state space paradigm. For such models, the important step of model validation rarely receives as much attention as estimation or hypothesis testing, perhaps due to lack of available algorithms and software. Model validation is often based on a naive...... for estimation in general mixed effects models. Implementing one-step predictions in the R package Template Model Builder, we demonstrate that it is possible to perform model validation with little effort, even if the ecological model is multivariate, has non-linear dynamics, and whether observations...... are continuous or discrete. With both simulated data, and a real data set related to geolocation of seals, we demonstrate both the potential and the limitations of the techniques. Our results fill a need for convenient methods for validating a state space model, or alternatively, rejecting it while indicating...
Space Weather: Measurements, Models and Predictions
2014-03-21
and record high levels of cosmic ray flux. There were broad-ranging terrestrial responses to this inactivity of the Sun. BC was involved in the...techniques for converting from one coordinate system (e.g., the invariant coordinate system used for the model) to another (e.g., the latitude- radius
Parton model in Lorentz invariant noncommutative space
Haghighat, M.; Ettefaghi, M. M.
2004-08-01
We consider the Lorentz invariant noncommutative QED and complete the Feynman rules for the theory up to the order θ2. In the Lorentz invariant version of the noncommutative QED the particles with fractional charges can be also considered. We show that in the parton model, even at the lowest order, the Bjorken scaling violates as ˜θ2Q4.
Interactions In Space For Archaeological Models
Evans, T S; Knappett, C
2011-01-01
In this article we examine a variety of quantitative models for describing archaeological networks, with particular emphasis on the maritime networks of the Aegean Middle Bronze Age. In particular, we discriminate between those gravitational networks that are most likely (maximum entropy) and most efficient (best cost/benefit outcomes).
Solvable Models on Noncommutative Spaces with Minimal Length Uncertainty Relations
Dey, Sanjib
2014-01-01
Our main focus is to explore different models in noncommutative spaces in higher dimensions. We provide a procedure to relate a three dimensional q-deformed oscillator algebra to the corresponding algebra satisfied by canonical variables describing non-commutative spaces. The representations for the corresponding operators obey algebras whose uncertainty relations lead to minimal length, areas and volumes in phase space, which are in principle natural candidates of many different approaches of quantum gravity. We study some explicit models on these types of noncommutative spaces, first by utilising the perturbation theory, later in an exact manner. In many cases the operators are not Hermitian, therefore we use PT -symmetry and pseudo-Hermiticity property, wherever applicable, to make them self-consistent. Apart from building mathematical models, we focus on the physical implications of noncommutative theories too. We construct Klauder coherent states for the perturbative and nonperturbative noncommutative ha...
Action Relations. Basic Design Concepts for Behaviour Modelling and Refinement.
Quartel, Dick
This thesis presents basic design concepts, design methods and a basic design language for distributed system behaviours. This language is based on two basic concepts: the action concept and the causality relation concept. Our methods focus on behaviour refinement, which consists of replacing an
Nongenomic actions of cortisol in the teleost lactotroph model
DEFF Research Database (Denmark)
Borski, Russell J; Tipsmark, Christian Kølbæk; Mita, M
2006-01-01
of the present study was to investigate the role of phospholipase C (PLC)-IP3 in mediating cortisol's actions. During 30 min and 4-hour incubation, chicken GnRH-II induces a 2-4 fold increase in PRL release from the tilapia pituitary. The stimulatory effect of cGnRH-II was reduced by cortisol, cortisol-21...
Parameter redundancy in discrete state‐space and integrated models
McCrea, Rachel S.
2016-01-01
Discrete state‐space models are used in ecology to describe the dynamics of wild animal populations, with parameters, such as the probability of survival, being of ecological interest. For a particular parametrization of a model it is not always clear which parameters can be estimated. This inability to estimate all parameters is known as parameter redundancy or a model is described as nonidentifiable. In this paper we develop methods that can be used to detect parameter redundancy in discrete state‐space models. An exhaustive summary is a combination of parameters that fully specify a model. To use general methods for detecting parameter redundancy a suitable exhaustive summary is required. This paper proposes two methods for the derivation of an exhaustive summary for discrete state‐space models using discrete analogues of methods for continuous state‐space models. We also demonstrate that combining multiple data sets, through the use of an integrated population model, may result in a model in which all parameters are estimable, even though models fitted to the separate data sets may be parameter redundant. PMID:27362826
Parameter redundancy in discrete state-space and integrated models.
Cole, Diana J; McCrea, Rachel S
2016-09-01
Discrete state-space models are used in ecology to describe the dynamics of wild animal populations, with parameters, such as the probability of survival, being of ecological interest. For a particular parametrization of a model it is not always clear which parameters can be estimated. This inability to estimate all parameters is known as parameter redundancy or a model is described as nonidentifiable. In this paper we develop methods that can be used to detect parameter redundancy in discrete state-space models. An exhaustive summary is a combination of parameters that fully specify a model. To use general methods for detecting parameter redundancy a suitable exhaustive summary is required. This paper proposes two methods for the derivation of an exhaustive summary for discrete state-space models using discrete analogues of methods for continuous state-space models. We also demonstrate that combining multiple data sets, through the use of an integrated population model, may result in a model in which all parameters are estimable, even though models fitted to the separate data sets may be parameter redundant. © 2016 The Author. Biometrical Journal published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
A Modeler's Perspective on Space Weather Forecasting (Invited)
Wiltberger, M. J.
2010-12-01
Space physics is moving into a new era where numerical models originally developed for answering science questions are used as the basis for making operational space weather forecasts. Answering this challenge requires developments on multiple fronts requiring collaborations across space physics disciplines and between the research and operations communities. Since space weather in geospace is driven by the solar wind conditions a natural solution to improving the forecast lead time is to couple geospace models to heliospheric models. The quality of these forecast is dependent upon the ability of the heliospheric models to accurately model IMF Bz. Another challenge presented by moving into the forecasting arena is preparing the models for real-time operation which includes both computational performance and data redundancy issues. Moving into operations also presents modelers with an opportunity to assess their models performance over calculation intervals unprecedented duration. A key collaboration in the transition of models to operation is the discussion between forecasters and developers on what forecast parameters can accurately be predicted by the current generation of numerical models. This collaboration naturally includes a discussion of the definition of the best metrics to be used in quantitatively assessing performance.
Listening to music primes space: pianists, but not novices, simulate heard actions.
Taylor, J Eric T; Witt, Jessica K
2015-03-01
Musicians sometimes report twitching in their fingers or hands while listening to music. This anecdote could be indicative of a tendency for auditory-motor co-representation in musicians. Here, we describe two studies showing that pianists (Experiment 1), but not novices (Experiment 2) automatically generate spatial representations that correspond to learned musical actions while listening to music. Participants made one-handed movements to the left or right from a central location in response to visual stimuli while listening to task-irrelevant auditory stimuli, which were scales played on a piano. These task-irrelevant scales were either ascending (compatible with rightward movements) or descending (compatible with leftward movements). Pianists were faster to respond when the scale direction was compatible with the direction of response movement, whereas novices' movements were unaffected by the scale. These results are in agreement with existing research on action-effect coupling in musicians, which draw heavily on common coding theory. In addition, these results show how intricate auditory stimuli (ascending or descending scales) evoke coarse, domain-general spatial representations.
Cities in Space: Three Simple Models
Paul Krugman
1991-01-01
Urban agglomerations arise at least in part out of the interaction between economies of scale in production and market size effects. This paper develops a simple spatial framework to develop illustrative models of the determinants of urban location, of the number and size of cities, and of the degree of urbanization. A Central theme is the probable existence of multiple equilibria, and the dependence of the range of potential outcomes on a few key parameters.
Royal London space analysis: plaster versus digital model assessment.
Grewal, Balpreet; Lee, Robert T; Zou, Lifong; Johal, Ama
2016-08-10
With the advent of digital study models, the importance of being able to evaluate space requirements becomes valuable to treatment planning and the justification for any required extraction pattern. This study was undertaken to compare the validity and reliability of the Royal London space analysis (RLSA) undertaken on plaster as compared with digital models. A pilot study (n = 5) was undertaken on plaster and digital models to evaluate the feasibility of digital space planning. This also helped to determine the sample size calculation and as a result, 30 sets of study models with specified inclusion criteria were selected. All five components of the RLSA, namely: crowding; depth of occlusal curve; arch expansion/contraction; incisor antero-posterior advancement and inclination (assessed from the pre-treatment lateral cephalogram) were accounted for in relation to both model types. The plaster models served as the gold standard. Intra-operator measurement error (reliability) was evaluated along with a direct comparison of the measured digital values (validity) with the plaster models. The measurement error or coefficient of repeatability was comparable for plaster and digital space analyses and ranged from 0.66 to 0.95mm. No difference was found between the space analysis performed in either the upper or lower dental arch. Hence, the null hypothesis was accepted. The digital model measurements were consistently larger, albeit by a relatively small amount, than the plaster models (0.35mm upper arch and 0.32mm lower arch). No difference was detected in the RLSA when performed using either plaster or digital models. Thus, digital space analysis provides a valid and reproducible alternative method in the new era of digital records.
A Space Radiation Test Model Study
1989-02-17
approxiniationis fi iso - the course of the ssork. tit, other criterion was applied to the latirig the dominant contributions to the right-hand side of...these Iso end gics (t 17, ; .i rli rlc population ire assUrnd sufficietitv issues, at discussion oif eachi is necessary at the outset high rhir i7...Lopez, J. Geophys. Res., 92, 13485 , 1987. B-16 GEOPHYSICAL RESEARCH LETTERS, VOL. 14, NO. 11, PACES 1166-1169, NDVEM13ER 1981 A NONLINEAR MODEL OF WAVE
Formulating state space models in R with focus on longitudinal regression models
DEFF Research Database (Denmark)
Dethlefsen, Claus; Lundbye-Christensen, Søren
We provide a language for formulating a range of state space models. The described methodology is implemented in the R -package sspir available from cran.r-project.org . A state space model is specified similarly to a generalized linear model in R , by marking the time-varying terms in the form...... We provide a language for formulating a range of state space models. The described methodology is implemented in the R -package sspir available from cran.r-project.org . A state space model is specified similarly to a generalized linear model in R , by marking the time-varying terms...
An integrated model for Jupiter's dynamo action and mean jet dynamics
Gastine, Thomas; Wicht, Johannes; Duarte, Lucia; Heimpel, Moritz
2014-05-01
Data from various space crafts revealed that Jupiter's large scale interior magnetic field is very Earth-like. This is surprising since numerical simulations have demonstrated that, for example, the radial dependence of density, electrical conductivity and other physical properties, which is only mild in the iron cores of terrestrial planets but very drastic in gas planets, can significantly affect the interior dynamics. Jupiter's dynamo action is thought to take place in the deeper envelope where hydrogen, the main constituent of Jupiter's atmosphere, assumes metallic properties. The potential interaction between the observed zonal jets and the deeper dynamo region is an unresolved problem with important consequences for the magnetic field generation. Here we present the first numerical simulation that is based on recent interior models and covers 99% of the planetary radius (below the 1 bar level). A steep decease in the electrical conductivity over the outer 10% in radius allowed us to model both the deeper metallic region and the outer molecular layer in an integrated approach. The magnetic field very closely reproduces Jupiter's known large scale field. A strong equatorial zonal jet remains constrained to the molecular layer while higher latitude jets are suppressed by Lorentz forces. This suggests that Jupiter's higher latitude jets remain shallow and are driven by an additional effect not captured in our deep convection model. The dynamo action of the equatorial jet produces a band of magnetic field located around the equator. The unprecedented magnetic field resolution expected from the Juno mission will allow to resolve this feature allowing a direct detection of the equatorial jet dynamics at depth. Typical secular variation times scales amount to around 750 yr for the dipole contribution but decrease to about 5 yr at the expected Juno resolution (spherical harmonic degree 20). At a nominal mission duration of one year Juno should therefore be able to
A probabilistic model of RNA conformational space
DEFF Research Database (Denmark)
Frellsen, Jes; Moltke, Ida; Thiim, Martin;
2009-01-01
The increasing importance of non-coding RNA in biology and medicine has led to a growing interest in the problem of RNA 3-D structure prediction. As is the case for proteins, RNA 3-D structure prediction methods require two key ingredients: an accurate energy function and a conformational sampling......, the discrete nature of the fragments necessitates the use of carefully tuned, unphysical energy functions, and their non-probabilistic nature impairs unbiased sampling. We offer a solution to the sampling problem that removes these important limitations: a probabilistic model of RNA structure that allows...... conformations for 9 out of 10 test structures, solely using coarse-grained base-pairing information. In conclusion, the method provides a theoretical and practical solution for a major bottleneck on the way to routine prediction and simulation of RNA structure and dynamics in atomic detail....
State-Space Modelling of Loudspeakers using Fractional Derivatives
DEFF Research Database (Denmark)
King, Alexander Weider; Agerkvist, Finn T.
2015-01-01
This work investigates the use of fractional order derivatives in modeling moving-coil loudspeakers. A fractional order state-space solution is developed, leading the way towards incorporating nonlinearities into a fractional order system. The method is used to calculate the response....... It is shown that the identified parameters can be used in a linear fractional order state-space model to simulate the loudspeakers’ time domain response...... of a fractional harmonic oscillator, representing the mechanical part of a loudspeaker, showing the effect of the fractional derivative and its relationship to viscoelasticity. Finally, a loudspeaker model with a fractional order viscoelastic suspension and fractional order voice coil is fit to measurement data...
Dynamic State Space Partitioning for External Memory Model Checking
DEFF Research Database (Denmark)
Evangelista, Sami; Kristensen, Lars Michael
2009-01-01
We describe a dynamic partitioning scheme usable by model checking techniques that divide the state space into partitions, such as most external memory and distributed model checking algorithms. The goal of the scheme is to reduce the number of transitions that link states belonging to different...
Applying reliability models to the maintenance of Space Shuttle software
Schneidewind, Norman F.
1992-01-01
Software reliability models provide the software manager with a powerful tool for predicting, controlling, and assessing the reliability of software during maintenance. We show how a reliability model can be effectively employed for reliability prediction and the development of maintenance strategies using the Space Shuttle Primary Avionics Software Subsystem as an example.
CAD-model-based vision for space applications
Shapiro, Linda G.
1988-01-01
A pose acquisition system operating in space must be able to perform well in a variety of different applications including automated guidance and inspections tasks with many different, but known objects. Since the space station is being designed with automation in mind, there will be CAD models of all the objects, including the station itself. The construction of vision models and procedures directly from the CAD models is the goal of this project. The system that is being designed and implementing must convert CAD models to vision models, predict visible features from a given view point from the vision models, construct view classes representing views of the objects, and use the view class model thus derived to rapidly determine the pose of the object from single images and/or stereo pairs.
Modeling of space-time focusing of localized nondiffracting pulses
Zamboni-Rached, Michel; Besieris, Ioannis M.
2016-10-01
In this paper we develop a method capable of modeling the space-time focusing of nondiffracting pulses. These pulses can possess arbitrary peak velocities and, in addition to being resistant to diffraction, can have their peak intensities and focusing positions chosen a priori. More specifically, we can choose multiple locations (spatial ranges) of space and time focalization; also, the pulse intensities can be chosen in advance. The pulsed wave solutions presented here can have very interesting applications in many different fields, such as free-space optical communications, remote sensing, medical apparatus, etc.
Modeling of Space-Time Focusing of Localized Nondiffracting Pulses
Zamboni-Rached, Michel
2015-01-01
In this paper we develop a method capable of modeling the space-time focusing of nondiffracting pulses. The new pulses can possess arbitrary peak velocities and, in addition to being resistant to diffraction, can have their peak intensities and focusing positions chosen a priori. More specifically, we can choose multiple locations (spatial ranges) of space/time focalization; also, the pulse intensities can be chosen in advance. The pulsed wave solutions presented here can have very interesting applications in many different fields, such as free-space optical communications, remote sensing, medical apparatus, etc.
Modeling electron fractionalization with unconventional Fock spaces
Cobanera, Emilio
2017-08-01
It is shown that certain fractionally-charged quasiparticles can be modeled on D-dimensional lattices in terms of unconventional yet simple Fock algebras of creation and annihilation operators. These unconventional Fock algebras are derived from the usual fermionic algebra by taking roots (the square root, cubic root, etc) of the usual fermionic creation and annihilation operators. If the fermions carry non-Abelian charges, then this approach fractionalizes the Abelian charges only. In particular, the mth-root of a spinful fermion carries charge e/m and spin 1/2. Just like taking a root of a complex number, taking a root of a fermion yields a mildly non-unique result. As a consequence, there are several possible choices of quantum exchange statistics for fermion-root quasiparticles. These choices are tied to the dimensionality D=1,2,3,\\ldots of the lattice by basic physical considerations. One particular family of fermion-root quasiparticles is directly connected to the parafermion zero-energy modes expected to emerge in certain mesoscopic devices involving fractional quantum Hall states. Hence, as an application of potential mesoscopic interest, I investigate numerically the hybridization of Majorana and parafermion zero-energy edge modes caused by fractionalizing but charge-conserving tunneling.
Mirror contamination in space I: mirror modelling
Krijger, J. M.; Snel, R.; van Harten, G.; Rietjens, J. H. H.; Aben, I.
2014-10-01
We present a comprehensive model that can be employed to describe and correct for degradation of (scan) mirrors and diffusers in satellite instruments that suffer from changing optical Ultraviolet to visible (UV-VIS) properties during their operational lifetime. As trend studies become more important, so does the importance of understanding and correcting for this degradation. This is the case not only with respect to the transmission of the optical components, but also with respect to wavelength, polarisation, or scan-angle effects. Our hypothesis is that mirrors in flight suffer from the deposition of a thin absorbing layer of contaminant, which slowly builds up over time. We describe this with the Mueller matrix formalism and Fresnel equations for thin multi-layer contamination films. Special care is taken to avoid the confusion often present in earlier publications concerning the Mueller matrix calculus with out-of-plane reflections. The method can be applied to any UV-VIS satellite instrument. We illustrate and verify our approach to the optical behaviour of the multiple scan mirrors of SCIAMACHY (onboard ENVISAT).
Tsapalis, Antonios S.
This thesis deals with two topics in lattice field theories. In the first part we discuss aspects of renormalization group flow and non-perturbative improvement of actions for scalar theories regularized on a lattice. We construct a perfect action, an action which is free of lattice artifacts, for a given theory. It is shown how a good approximation to the perfect action-referred to as classically perfect-can be constructed based on a well-defined blocking scheme for the O(3) non-linear σ-model. We study the O(N) non- linear σ-model in the large-N limit and derive analytically its perfect action. This action is applied to the O(3) model on a square lattice. The Wolff cluster algorithm is used to simulate numerically the system. We perform scaling tests and discuss the scaling properties of the large- N inspired perfect action as opposed to the standard and the classically perfect action. In the second part we present a new formulation for a quantum field theory with Abelian gauge symmetry. A Hamiltonian is constructed on a four-dimensional Euclidean space-time lattice which is invariant under local transformations. The model is formulated as a 5- dimensional path integral of discrete variables. We argue that dimensional reduction will allow us to study the behavior of the standard compact U(1) gauge theory in 4-d. Based on the idea of the loop- cluster algorithm for quantum spins, we present the construction of a flux-cluster algorithm for the U(1) quantum link model for the spin-1/2 quantization of the electric flux. It is shown how improved estimators for Wilson loop expectation values can be defined. This is important because the Wilson loops are traditionally used to identify confining and Coulomb phases in gauge theories. Our study indicates that the spin-1/2 U(1) quantum link model is strongly coupled for all bare coupling values we examined. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)
A stochastic space-time model for intermittent precipitation occurrences
Sun, Ying
2016-01-28
Modeling a precipitation field is challenging due to its intermittent and highly scale-dependent nature. Motivated by the features of high-frequency precipitation data from a network of rain gauges, we propose a threshold space-time t random field (tRF) model for 15-minute precipitation occurrences. This model is constructed through a space-time Gaussian random field (GRF) with random scaling varying along time or space and time. It can be viewed as a generalization of the purely spatial tRF, and has a hierarchical representation that allows for Bayesian interpretation. Developing appropriate tools for evaluating precipitation models is a crucial part of the model-building process, and we focus on evaluating whether models can produce the observed conditional dry and rain probabilities given that some set of neighboring sites all have rain or all have no rain. These conditional probabilities show that the proposed space-time model has noticeable improvements in some characteristics of joint rainfall occurrences for the data we have considered.
From Diagnosis to Action: An Automated Failure Advisor for Human Deep Space Missions
Colombano, Silvano; Spirkovska, Lilly; Baskaran, Vijayakumar; Morris, Paul; Mcdermott, William; Ossenfort, John; Bajwa, Anupa
2015-01-01
The major goal of current space system development at NASA is to enable human travel to deep space locations such as Mars and asteroids. At that distance, round trip communication with ground operators may take close to an hour, thus it becomes unfeasible to seek ground operator advice for problems that require immediate attention, either for crew safety or for activities that need to be performed at specific times for the attainment of scientific results. To achieve this goal, major reliance will need to be placed on automation systems capable of aiding the crew in detecting and diagnosing failures, assessing consequences of these failures, and providing guidance in repair activities that may be required. We report here on the most current step in the continuing development of such a system, and that is the addition of a Failure Response Advisor. In simple terms, we have a system in place the Advanced Caution and Warning System (ACAWS) to tell us what happened (failure diagnosis) and what happened because that happened (failure effects). The Failure Response Advisor will tell us what to do about it, how long until something must be done and why its important that something be done and will begin to approach the complex reasoning that is generally required for an optimal approach to automated system health management. This advice is based on the criticality and various timing elements, such as durations of activities and of component repairs, failure effects delay, and other factors. The failure advice is provided to operators (crew and mission controllers) together with the diagnostic and effects information. The operators also have the option to drill down for more information about the failure and the reasons for any suggested priorities.
Probabilistic Hybrid Action Models for Predicting Concurrent Percept-driven Robot Behavior
Beetz, M; 10.1613/jair.1565
2011-01-01
This article develops Probabilistic Hybrid Action Models (PHAMs), a realistic causal model for predicting the behavior generated by modern percept-driven robot plans. PHAMs represent aspects of robot behavior that cannot be represented by most action models used in AI planning: the temporal structure of continuous control processes, their non-deterministic effects, several modes of their interferences, and the achievement of triggering conditions in closed-loop robot plans. The main contributions of this article are: (1) PHAMs, a model of concurrent percept-driven behavior, its formalization, and proofs that the model generates probably, qualitatively accurate predictions; and (2) a resource-efficient inference method for PHAMs based on sampling projections from probabilistic action models and state descriptions. We show how PHAMs can be applied to planning the course of action of an autonomous robot office courier based on analytical and experimental results.
NASA Space Radiation Program Integrative Risk Model Toolkit
Kim, Myung-Hee Y.; Hu, Shaowen; Plante, Ianik; Ponomarev, Artem L.; Sandridge, Chris
2015-01-01
NASA Space Radiation Program Element scientists have been actively involved in development of an integrative risk models toolkit that includes models for acute radiation risk and organ dose projection (ARRBOD), NASA space radiation cancer risk projection (NSCR), hemocyte dose estimation (HemoDose), GCR event-based risk model code (GERMcode), and relativistic ion tracks (RITRACKS), NASA radiation track image (NASARTI), and the On-Line Tool for the Assessment of Radiation in Space (OLTARIS). This session will introduce the components of the risk toolkit with opportunity for hands on demonstrations. The brief descriptions of each tools are: ARRBOD for Organ dose projection and acute radiation risk calculation from exposure to solar particle event; NSCR for Projection of cancer risk from exposure to space radiation; HemoDose for retrospective dose estimation by using multi-type blood cell counts; GERMcode for basic physical and biophysical properties for an ion beam, and biophysical and radiobiological properties for a beam transport to the target in the NASA Space Radiation Laboratory beam line; RITRACKS for simulation of heavy ion and delta-ray track structure, radiation chemistry, DNA structure and DNA damage at the molecular scale; NASARTI for modeling of the effects of space radiation on human cells and tissue by incorporating a physical model of tracks, cell nucleus, and DNA damage foci with image segmentation for the automated count; and OLTARIS, an integrated tool set utilizing HZETRN (High Charge and Energy Transport) intended to help scientists and engineers study the effects of space radiation on shielding materials, electronics, and biological systems.
Stringy Models of Modified Gravity: Space-time defects and Structure Formation
Mavromatos, Nick E.
2013-01-01
Starting from microscopic models of space-time foam, based on brane universes propagating in bulk space-times populated by D0-brane defects ("D-particles"), we arrive at effective actions used by a low-energy observer on the brane world to describe his/her observations of the Universe. These actions include, apart from the metric tensor field, also scalar (dilaton) and vector fields, the latter describing the interactions of low-energy matter on the brane world with the recoiling point-like space-time defect (D-particle). The vector field is proportional to the recoil velocity of the D-particle and as such it satisfies a certain constraint. The vector breaks locally Lorentz invariance, which however is assumed to be conserved on average in a space-time foam situation, involving the interaction of matter with populations of D-particle defects. In this paper we demonstrate that, already at the end of the radiation era, the (constrained) vector field associated with the recoil of the defects provides the seeds f...
Estimation methods for nonlinear state-space models in ecology
DEFF Research Database (Denmark)
Pedersen, Martin Wæver; Berg, Casper Willestofte; Thygesen, Uffe Høgsbro
2011-01-01
The use of nonlinear state-space models for analyzing ecological systems is increasing. A wide range of estimation methods for such models are available to ecologists, however it is not always clear, which is the appropriate method to choose. To this end, three approaches to estimation in the theta...... logistic model for population dynamics were benchmarked by Wang (2007). Similarly, we examine and compare the estimation performance of three alternative methods using simulated data. The first approach is to partition the state-space into a finite number of states and formulate the problem as a hidden...... Markov model (HMM). The second method uses the mixed effects modeling and fast numerical integration framework of the AD Model Builder (ADMB) open-source software. The third alternative is to use the popular Bayesian framework of BUGS. The study showed that state and parameter estimation performance...
Continuous-time discrete-space models for animal movement
Hanks, Ephraim M.; Hooten, Mevin B.; Alldredge, Mat W.
2015-01-01
The processes influencing animal movement and resource selection are complex and varied. Past efforts to model behavioral changes over time used Bayesian statistical models with variable parameter space, such as reversible-jump Markov chain Monte Carlo approaches, which are computationally demanding and inaccessible to many practitioners. We present a continuous-time discrete-space (CTDS) model of animal movement that can be fit using standard generalized linear modeling (GLM) methods. This CTDS approach allows for the joint modeling of location-based as well as directional drivers of movement. Changing behavior over time is modeled using a varying-coefficient framework which maintains the computational simplicity of a GLM approach, and variable selection is accomplished using a group lasso penalty. We apply our approach to a study of two mountain lions (Puma concolor) in Colorado, USA.
Geodetic Space Weather Monitoring by means of Ionosphere Modelling
Schmidt, Michael
2017-04-01
The term space weather indicates physical processes and phenomena in space caused by radiation of energy mainly from the Sun. Manifestations of space weather are (1) variations of the Earth's magnetic field, (2) the polar lights in the northern and southern hemisphere, (3) variations within the ionosphere as part of the upper atmosphere characterized by the existence of free electrons and ions, (4) the solar wind, i.e. the permanent emission of electrons and photons, (5) the interplanetary magnetic field, and (6) electric currents, e.g. the van Allen radiation belt. It can be stated that ionosphere disturbances are often caused by so-called solar storms. A solar storm comprises solar events such as solar flares and coronal mass ejections (CMEs) which have different effects on the Earth. Solar flares may cause disturbances in positioning, navigation and communication. CMEs can effect severe disturbances and in extreme cases damages or even destructions of modern infrastructure. Examples are interruptions to satellite services including the global navigation satellite systems (GNSS), communication systems, Earth observation and imaging systems or a potential failure of power networks. Currently the measurements of solar satellite missions such as STEREO and SOHO are used to forecast solar events. Besides these measurements the Earth's ionosphere plays another key role in monitoring the space weather, because it responses to solar storms with an increase of the electron density. Space-geodetic observation techniques, such as terrestrial GNSS, satellite altimetry, space-borne GPS (radio occultation), DORIS and VLBI provide valuable global information about the state of the ionosphere. Additionally geodesy has a long history and large experience in developing and using sophisticated analysis and combination techniques as well as empirical and physical modelling approaches. Consequently, geodesy is predestinated for strongly supporting space weather monitoring via
Modeling of space environment impact on nanostructured materials. General principles
Voronina, Ekaterina; Novikov, Lev
2016-07-01
In accordance with the resolution of ISO TC20/SC14 WG4/WG6 joint meeting, Technical Specification (TS) 'Modeling of space environment impact on nanostructured materials. General principles' which describes computer simulation methods of space environment impact on nanostructured materials is being prepared. Nanomaterials surpass traditional materials for space applications in many aspects due to their unique properties associated with nanoscale size of their constituents. This superiority in mechanical, thermal, electrical and optical properties will evidently inspire a wide range of applications in the next generation spacecraft intended for the long-term (~15-20 years) operation in near-Earth orbits and the automatic and manned interplanetary missions. Currently, ISO activity on developing standards concerning different issues of nanomaterials manufacturing and applications is high enough. Most such standards are related to production and characterization of nanostructures, however there is no ISO documents concerning nanomaterials behavior in different environmental conditions, including the space environment. The given TS deals with the peculiarities of the space environment impact on nanostructured materials (i.e. materials with structured objects which size in at least one dimension lies within 1-100 nm). The basic purpose of the document is the general description of the methodology of applying computer simulation methods which relate to different space and time scale to modeling processes occurring in nanostructured materials under the space environment impact. This document will emphasize the necessity of applying multiscale simulation approach and present the recommendations for the choice of the most appropriate methods (or a group of methods) for computer modeling of various processes that can occur in nanostructured materials under the influence of different space environment components. In addition, TS includes the description of possible
Orbital Optimization in the Active Space Decomposition Model
Kim, Inkoo; Shiozaki, Toru
2015-01-01
We report the derivation and implementation of orbital optimization algorithms for the active space decomposition (ASD) model, which are extensions of complete active space self-consistent field (CASSCF) and its occupation-restricted variants in the conventional multiconfiguration electronic-structure theory. Orbital rotations between active subspaces are included in the optimization, which allows us to unambiguously partition the active space into subspaces, enabling application of ASD to electron and exciton dynamics in covalently linked chromophores. One- and two-particle reduced density matrices, which are required for evaluation of orbital gradient and approximate Hessian elements, are computed from the intermediate tensors in the ASD energy evaluation. Numerical results on 4-(2-naphthylmethyl)-benzaldehyde and [3$_6$]cyclophane and model Hamiltonian analyses of triplet energy transfer processes in the Closs systems are presented. Furthermore model Hamiltonians for hole and electron transfer processes in...
Semi-Automated Design Space Exploration for Formal Modelling
Grov, Gudmund; Ireland, Andrew; Llano, Maria Teresa; Kovacs, Peter; Colton, Simon; Gow, Jeremy
2016-01-01
Refinement based formal methods allow the modelling of systems through incremental steps via abstraction. Discovering the right levels of abstraction, formulating correct and meaningful invariants, and analysing faulty models are some of the challenges faced when using this technique. Here, we propose Design Space Exploration, an approach that aims to assist a designer by automatically providing high-level modelling guidance in real-time. More specifically, through the combination of common p...
Space and Time Ontology: New Models for New Physics
Directory of Open Access Journals (Sweden)
Sara Lumbreras Sancho
2015-02-01
Full Text Available Nickel proposes a model for movement – and in general, for change – in which each instant in time (characterized as the set of real numbers is assigned to one point in a configuration space. As much as this model seems to intuitively fit to our experience, it implies a number of assumptions about the nature of space and time that are interesting to explore. Different perspectives have been developed across History, and it could well be that the next scientific revolution is set in motion by an innovative conception of space and time. One of this alternative perspectives was proposed by Julian Barbour, who has developed a new model of Physics where time does not exist [Barbour, 1999]. This paper reviews not only this concept but also other similarly provocative ideas that might prove useful for improving our understanding of the universe. Prior to this, the relevance of the philosophy of space and time will be briefly outlined and its history reviewed to provide some background for the discussed models. Finally, an approach where space and time are only defined by convention will be considered.
Space Surveillance Network Scheduling Under Uncertainty: Models and Benefits
Valicka, C.; Garcia, D.; Staid, A.; Watson, J.; Rintoul, M.; Hackebeil, G.; Ntaimo, L.
2016-09-01
Advances in space technologies continue to reduce the cost of placing satellites in orbit. With more entities operating space vehicles, the number of orbiting vehicles and debris has reached unprecedented levels and the number continues to grow. Sensor operators responsible for maintaining the space catalog and providing space situational awareness face an increasingly complex and demanding scheduling requirements. Despite these trends, a lack of advanced tools continues to prevent sensor planners and operators from fully utilizing space surveillance resources. One key challenge involves optimally selecting sensors from a network of varying capabilities for missions with differing requirements. Another open challenge, the primary focus of our work, is building robust schedules that effectively plan for uncertainties associated with weather, ad hoc collections, and other target uncertainties. Existing tools and techniques are not amenable to rigorous analysis of schedule optimality and do not adequately address the presented challenges. Building on prior research, we have developed stochastic mixed-integer linear optimization models to address uncertainty due to weather's effect on collection quality. By making use of the open source Pyomo optimization modeling software, we have posed and solved sensor network scheduling models addressing both forms of uncertainty. We present herein models that allow for concurrent scheduling of collections with the same sensor configuration and for proactively scheduling against uncertain ad hoc collections. The suitability of stochastic mixed-integer linear optimization for building sensor network schedules under different run-time constraints will be discussed.
Pyle, E. J.
2013-12-01
The Next Generation Science Standards (NGSS) are a step forward in ensuring that future generations of students become scientifically literate. The NGSS document builds from the National Science Education Standards (1996) and the National Assessment of Educational Progress (NAEP) science framework of 2005. Design teams for the Curriculum Framework for K-12 Science Education were to outline the essential content necessary for students' science literacy, considering the foundational knowledge and the structure of each discipline in the context of learning progressions. Once draft standards were developed, two issues emerged from their review: (a) the continual need to prune 'cherished ideas' within the content, such that only essential ideas were represented, and (b) the potential for prior conceptions of Science & Engineering Practices (SEP) and cross-cutting concepts (CCC) to limit overly constrain performance expectations. With the release of the NGSS, several challenges are emerging for geoscience education. First, the traditional emphasis of Earth science in middle school has been augmented by new standards for high school that require major syntheses of concepts. Second, the integration of SEPs into performance expectations places an increased burden on teachers and curriculum developers to organize instruction around the nature of inquiry in the geosciences. Third, work is needed to define CCCs in Earth contexts, such that the unique structure of the geosciences is best represented. To ensure that the Earth & Space Science standards are implemented through grade 12, two supporting structures must be developed. In the past, many curricular materials claimed that they adhered to the NSES, but in some cases this match was a simple word match or checklist that bore only superficial resemblance to the standards. The structure of the performance expectations is of sufficient sophistication to ensure that adherence to the standards more than a casual exercise. Claims
Nonlinear sigma models with compact hyperbolic target spaces
Gubser, Steven; Saleem, Zain H.; Schoenholz, Samuel S.; Stoica, Bogdan; Stokes, James
2016-06-01
We explore the phase structure of nonlinear sigma models with target spaces corresponding to compact quotients of hyperbolic space, focusing on the case of a hyperbolic genus-2 Riemann surface. The continuum theory of these models can be approximated by a lattice spin system which we simulate using Monte Carlo methods. The target space possesses interesting geometric and topological properties which are reflected in novel features of the sigma model. In particular, we observe a topological phase transition at a critical temperature, above which vortices proliferate, reminiscent of the Kosterlitz-Thouless phase transition in the O(2) model [1, 2]. Unlike in the O(2) case, there are many different types of vortices, suggesting a possible analogy to the Hagedorn treatment of statistical mechanics of a proliferating number of hadron species. Below the critical temperature the spins cluster around six special points in the target space known as Weierstrass points. The diversity of compact hyperbolic manifolds suggests that our model is only the simplest example of a broad class of statistical mechanical models whose main features can be understood essentially in geometric terms.
Transformation of Neural State Space Models into LFT Models for Robust Control Design
DEFF Research Database (Denmark)
Bendtsen, Jan Dimon; Trangbæk, Klaus
2000-01-01
This paper considers the extraction of linear state space models and uncertainty models from neural networks trained as state estimators with direct application to robust control. A new method for writing a neural state space model in a linear fractional transformation form in a non...
Formulating state space models in R with focus on longitudinal regression models
DEFF Research Database (Denmark)
Dethlefsen, Claus; Lundbye-Christensen, Søren
2006-01-01
We provide a language for formulating a range of state space models with response densities within the exponential family. The described methodology is implemented in the R-package sspir. A state space model is specified similarly to a generalized linear model in R, and then the time-varying terms...
A Right Coprime Factorization of Neural State Space Models
DEFF Research Database (Denmark)
Bendtsen, Jan Dimon
2007-01-01
In recent years, various methods for identification of nonlinear systems in closed loop using open-loop approaches have received considerable attention. However, these methods rely on differentially coprime factorizations of the nonlinear plants, which can be difficult to compute in practice....... To address this issue, this paper presents various technical results leading up to explicit formulae for right coprime factorizations of neural state space models, i.e., nonlinear system models represented in state space using neural networks, which satisfy a Bezout identity. ...
SpaceWire model development technology for satellite architecture.
Energy Technology Data Exchange (ETDEWEB)
Eldridge, John M.; Leemaster, Jacob Edward; Van Leeuwen, Brian P.
2011-09-01
Packet switched data communications networks that use distributed processing architectures have the potential to simplify the design and development of new, increasingly more sophisticated satellite payloads. In addition, the use of reconfigurable logic may reduce the amount of redundant hardware required in space-based applications without sacrificing reliability. These concepts were studied using software modeling and simulation, and the results are presented in this report. Models of the commercially available, packet switched data interconnect SpaceWire protocol were developed and used to create network simulations of data networks containing reconfigurable logic with traffic flows for timing system distribution.
Kane Method Based Dynamics Modeling and Control Study for Space Manipulator Capturing a Space Target
Directory of Open Access Journals (Sweden)
Yanhua Han
2016-01-01
Full Text Available Dynamics modeling and control problem of a two-link manipulator mounted on a spacecraft (so-called carrier freely flying around a space target on earth’s circular orbit is studied in the paper. The influence of the carrier’s relative movement on its manipulator is considered in dynamics modeling; nevertheless, that of the manipulator on its carrier is neglected with the assumption that the mass and inertia moment of the manipulator is far less than that of the carrier. Meanwhile, we suppose that the attitude control system of the carrier guarantees its side on which the manipulator is mounted points accurately always the space target during approaching operation. The ideal constraint forces can be out of consideration in dynamics modeling as Kane method is used. The path functions of the manipulator’s end-effector approaching the space target as well as the manipulator’s joints control torque functions are programmed to meet the soft touch requirement that the end-effector’s relative velocity to the space target is zero at touch moment. Numerical simulation validation is conducted finally.
Man in space - The use of animal models
Ballard, Rodney W.; Souza, Kenneth A.
1991-01-01
The use of animal surrogates as experimental subjects in order to provide essential missing information on the effects of long-term spaceflights, to validate countermeasures, and to test medical treatment techniques is discussed. Research needs also include the definition of biomedical adaptations to flight, and the developments of standards for safe space missions to assure human health and productivity during and following flight. NASA research plans in this area are outlined. Over the next 40 years, NASA plans to concentrate on the use of rodents and nonhuman primates as the models of choice for various physiological responses observed in humans during extended stays in space. This research will include flights on the Space Shuttle, unmanned biosatellites, and the Space Station Freedom.
A hypocentral version of the space-time ETAS model
Guo, Yicun; Zhuang, Jiancang; Zhou, Shiyong
2015-10-01
The space-time Epidemic-Type Aftershock Sequence (ETAS) model is extended by incorporating the depth component of earthquake hypocentres. The depths of the direct offspring produced by an earthquake are assumed to be independent of the epicentre locations and to follow a beta distribution, whose shape parameter is determined by the depth of the parent event. This new model is verified by applying it to the Southern California earthquake catalogue. The results show that the new model fits data better than the original epicentre ETAS model and that it provides the potential for modelling and forecasting seismicity with higher resolutions.
Methodology of problem space modeling in industrial enterprise management system
Directory of Open Access Journals (Sweden)
V.V. Glushchevsky
2015-03-01
Full Text Available The aim of the article. The aim of the article is to develop methodological principles for building a problem space model which can be integrated into industrial enterprise management system. The results of the analysis. The author developed methodological principles for constructing the problem space of an industrial enterprise as a structural and functional model. These problems appear on enterprise business process network topology and can be solved by its management system. The centerpiece of the article is description of the main stages of implementation of modeling methodology of industrial enterprise typical management problems. These stages help to solve several units of organizational management system structure of enterprise within their functional competence. Author formulated an axiom system of structural and characteristic properties of modeling space problems elements, and interconnections between them. This system of axioms is actually a justification for the correctness and adequacy of the proposed modeling methodology and comes as theoretical basis in the construction of the structural and functional model of the management problems space. This model generalizes three basic structural components of the enterprise management system with the help of axioms system: a three-dimensional model of the management problem space (the first dimension is the enterprise business process network, the second dimension is a set of management problems, the third dimension is four vectors of measurable and qualitative characteristics of management problems, which can be analyzed and managed during enterprise functioning; a two-dimensional model of the cybernetic space of analytical problems, which are formalized form of management problems (multivariate model experiments can be implemented with the help of this model to solve wide range of problem situations and determine the most effective or optimal management solutions; a two-dimensional model
Nonlinear regime-switching state-space (RSSS) models.
Chow, Sy-Miin; Zhang, Guangjian
2013-10-01
Nonlinear dynamic factor analysis models extend standard linear dynamic factor analysis models by allowing time series processes to be nonlinear at the latent level (e.g., involving interaction between two latent processes). In practice, it is often of interest to identify the phases--namely, latent "regimes" or classes--during which a system is characterized by distinctly different dynamics. We propose a new class of models, termed nonlinear regime-switching state-space (RSSS) models, which subsumes regime-switching nonlinear dynamic factor analysis models as a special case. In nonlinear RSSS models, the change processes within regimes, represented using a state-space model, are allowed to be nonlinear. An estimation procedure obtained by combining the extended Kalman filter and the Kim filter is proposed as a way to estimate nonlinear RSSS models. We illustrate the utility of nonlinear RSSS models by fitting a nonlinear dynamic factor analysis model with regime-specific cross-regression parameters to a set of experience sampling affect data. The parallels between nonlinear RSSS models and other well-known discrete change models in the literature are discussed briefly.
The Things You Do: Internal Models of Others' Expected Behaviour Guide Action Observation.
Schenke, Kimberley C; Wyer, Natalie A; Bach, Patric
2016-01-01
Predictions allow humans to manage uncertainties within social interactions. Here, we investigate how explicit and implicit person models-how different people behave in different situations-shape these predictions. In a novel action identification task, participants judged whether actors interacted with or withdrew from objects. In two experiments, we manipulated, unbeknownst to participants, the two actors action likelihoods across situations, such that one actor typically interacted with one object and withdrew from the other, while the other actor showed the opposite behaviour. In Experiment 2, participants additionally received explicit information about the two individuals that either matched or mismatched their actual behaviours. The data revealed direct but dissociable effects of both kinds of person information on action identification. Implicit action likelihoods affected response times, speeding up the identification of typical relative to atypical actions, irrespective of the explicit knowledge about the individual's behaviour. Explicit person knowledge, in contrast, affected error rates, causing participants to respond according to expectations instead of observed behaviour, even when they were aware that the explicit information might not be valid. Together, the data show that internal models of others' behaviour are routinely re-activated during action observation. They provide first evidence of a person-specific social anticipation system, which predicts forthcoming actions from both explicit information and an individuals' prior behaviour in a situation. These data link action observation to recent models of predictive coding in the non-social domain where similar dissociations between implicit effects on stimulus identification and explicit behavioural wagers have been reported.
Speed limit in internal space of domain walls via all-order effective action of moduli motion
Eto, Minoru; Hashimoto, Koji
2016-03-01
We find that motion in internal moduli spaces of generic domain walls has an upper bound for its velocity. Our finding is based on our generic formula for all-order effective actions of internal moduli parameter of domain wall solitons. It is known that the Nambu-Goldstone mode Z associated with spontaneous breaking of translation symmetry obeys a Nambu-Goto effective Lagrangian √{1 -(∂0Z )2 } detecting the speed of light (|∂0Z |=1 ) in the target spacetime. Solitons can have internal moduli parameters as well, associated with a breaking of internal symmetries such as a phase rotation acting on a field. We obtain, for generic domain walls, an effective Lagrangian of the internal moduli ɛ to all orders in (∂ɛ ). The Lagrangian is given by a function of the Nambu-Goto Lagrangian: L =g (√{1 +(∂μɛ )2 }). This shows generically the existence of an upper bound on ∂0ɛ , i.e., a speed limit in the internal space. The speed limit exists even for solitons in some nonrelativistic field theories, where we find that ɛ is a type I Nambu-Goldstone mode that also obeys a nonlinear dispersion to reach the speed limit. This offers a possibility of detecting the speed limit in condensed matter experiments.
Speed limit in internal space of domain walls via all-order effective action of moduli motion
Eto, Minoru
2015-01-01
We find that motion in internal moduli spaces of generic domain walls has an upper bound for its velocity. Our finding is based on our generic formula for all-order effective actions of internal moduli parameter of domain wall solitons. It is known that the Nambu-Goldstone mode $Z$ associated with spontaneous breaking of translation symmetry obeys a Nambu-Goto effective Lagrangian $\\sqrt{1 - (\\partial_0 Z)^2}$ detecting the speed of light ($|\\partial_0 Z|=1$) in the target spacetime. Solitons can have internal moduli parameters as well, associated with a breaking of internal symmetries such as a phase rotation acting on a field. We obtain, for generic domain walls, an effective Lagrangian of the internal moduli $\\epsilon$ to all order in $(\\partial \\epsilon)$. The Lagrangian is given by a function of the Nambu-Goto Lagrangian: $L = g(\\sqrt{1 + (\\partial_\\mu \\epsilon)^2})$. This shows generically the existence of an upper bound on $\\partial_0 \\epsilon$, i.e. a speed limit in the internal space. The speed limit...
Processing Approach of Non-linear Adjustment Models in the Space of Non-linear Models
Institute of Scientific and Technical Information of China (English)
LI Chaokui; ZHU Qing; SONG Chengfang
2003-01-01
This paper investigates the mathematic features of non-linear models and discusses the processing way of non-linear factors which contributes to the non-linearity of a nonlinear model. On the basis of the error definition, this paper puts forward a new adjustment criterion, SGPE.Last, this paper investigates the solution of a non-linear regression model in the non-linear model space and makes the comparison between the estimated values in non-linear model space and those in linear model space.
Initiation-promotion model of tumor prevalence in mice from space radiation exposures.
Cucinotta, F A; Wilson, J W
1995-08-01
Exposures in space consist of low-level background components from galactic cosmic rays (GCR), occasional intense-energetic solar-particle events, periodic passes through geomagnetic-trapped radiation, and exposure from possible onboard nuclear-propulsion engines. Risk models for astronaut exposure from such diverse components and modalities must be developed to assure adequate protection in future NASA missions. The low-level background exposures (GCR), including relativistic heavy ions (HZE), will be the ultimate limiting factor for astronaut career exposure. We consider herein a two-mutation, initiation-promotion, radiation-carcinogenesis model in mice in which the initiation stage is represented by a linear kinetics model of cellular repair/misrepair, including the track-structure model for heavy ion action cross-sections. The model is validated by comparison with the harderian gland tumor experiments of Alpen et al. for various ion beams. We apply the initiation-promotion model to exposures from galactic cosmic rays, using models of the cosmic-ray environment and heavy ion transport, and consider the effects of the age of the mice prior to and after the exposure and of the length of time in space on predictions of relative risk. Our results indicate that biophysical models of age-dependent radiation hazard will provide a better understanding of GCR risk than models that rely strictly on estimates of the initial slopes of these radiations.
The Cosmological Constant for the Crystalline Vacuum Cosmic Space Model
Montemayor-Aldrete, J A; Morales-Mori, A; Mendoza-Allende, A; Montemayor-Varela, A; Castillo-Mussot, M; Vazquez, G J
2005-01-01
The value of the cosmological constant arising from a crystalline model for vacuum cosmic space with lattice parameter of the order of the neutron radius [1] has been calculated. The model allows to solve, in an easy way, the problem of the cosmological constant giving the right order of magnitude, which corresponds very well with the mean value of matter density in the universe. The obtained value is about 10-48 Km-2. Diffraction experiments with non-thermal neutron beam in cosmic space are proposed to search for the possibility of crystalline structure of vacuum space and to measure the lattice parameter. PACS numbers: 98.80.Es, 04.20.-q, 03.65.-w, 61.50.-f, 98.80.Ft
Multi-scale gravity field modeling in space and time
Wang, Shuo; Panet, Isabelle; Ramillien, Guillaume; Guilloux, Frédéric
2016-04-01
The Earth constantly deforms as it undergoes dynamic phenomena, such as earthquakes, post-glacial rebound and water displacement in its fluid envelopes. These processes have different spatial and temporal scales and are accompanied by mass displacements, which create temporal variations of the gravity field. Since 2002, the GRACE satellite missions provide an unprecedented view of the gravity field spatial and temporal variations. Gravity models built from these satellite data are essential to study the Earth's dynamic processes (Tapley et al., 2004). Up to present, time variations of the gravity field are often modelled using spatial spherical harmonics functions averaged over a fixed period, as 10 days or 1 month. This approach is well suited for modeling global phenomena. To better estimate gravity related to local and/or transient processes, such as earthquakes or floods, and adapt the temporal resolution of the model to its spatial resolution, we propose to model the gravity field using localized functions in space and time. For that, we build a model of the gravity field in space and time with a four-dimensional wavelet basis, well localized in space and time. First we design the 4D basis, then, we study the inverse problem to model the gravity field from the potential differences between the twin GRACE satellites, and its regularization using prior knowledge on the water cycle. Our demonstration of surface water mass signals decomposition in time and space is based on the use of synthetic along-track gravitational potential data. We test the developed approach on one year of 4D gravity modeling and compare the reconstructed water heights to those of the input hydrological model. Perspectives of this work is to apply the approach on real GRACE data, addressing the challenge of a realistic noise, to better describe and understand physical processus with high temporal resolution/low spatial resolution or the contrary.
2009-01-01
Seezink, A., Poell, R. F., & Kirschner, P. A. (2009). Teachers' individual action theories about competence-based education: The value of the cognitive apprenticeship model. Journal of Vocational Education & Training, 61, 203-215.
Cramer, Mary E; Lazure, Linda; Morris, Kathy J; Valerio, Marilyn; Morris, Rosanna
2013-01-01
The RWJF/AARP National Campaign for Action established a goal of establishing Action Coalitions in every state by 2012. Last year, a small Steering Committee formed in Nebraska and used two conceptual models to guide the organization and development of its Action Coalition. The purpose of this article is to present the Internal Coalition Outcome Hierarchy (ICOH) model that guided development of partnership and coalition building. The second model, Determining Program Feasibility, provided a framework for data collection and analysis to identify the opportunities and challenges for strategic program planning to accomplish identified key priorities for Nebraska. A discussion of the models' applications is included and offered as best practices for others seeking to form partnership/coalitions and establish action plans and priorities. Copyright © 2013 Elsevier Inc. All rights reserved.
Holographic Space-time Models of Anti-deSitter Space-times
Banks, Tom
2016-01-01
We study the constraints on HST models of AdS space-time. The causal diamonds of HST along time-like geodesics of AdS space-time, fit nicely into the FRW patch of AdS space. The coordinate singularity of the FRW patch is identified with the proper time at which the Hilbert space of the causal diamond becomes infinite dimensional. For diamonds much smaller than the AdS radius, RAdS, the time dependent Hamiltonians of HST are the same as those used to describe similar diamonds in Minkowski space. In particular, they are invariant under the fuzzy analog of volume preserving diffeomorphisms of the holographic screen, which leads to fast scrambling of perturbations on the horizon of a black hole of size smaller than RAdS. We argue that, in order to take a limit of this system which converges to a CFT, one must choose Hamiltonians, in a range of proper times of order RAdS, which break this invariance, and become local in a particular choice of basis for the variables. We show that, beginning with flat, sub-RAdS, pa...
Interfacial and Wall Transport Models for SPACE-CAP Code
Energy Technology Data Exchange (ETDEWEB)
Hong, Soon Joon; Choo, Yeon Joon; Han, Tae Young; Hwang, Su Hyun; Lee, Byung Chul [FNC Tech., Seoul (Korea, Republic of); Choi, Hoon; Ha, Sang Jun [Korea Electric Power Research Institute, Daejeon (Korea, Republic of)
2009-10-15
The development project for the domestic design code was launched to be used for the safety and performance analysis of pressurized light water reactors. And CAP (Containment Analysis Package) code has been also developed for the containment safety and performance analysis side by side with SPACE. The CAP code treats three fields (gas, continuous liquid, and dispersed drop) for the assessment of containment specific phenomena, and is featured by its multidimensional assessment capabilities. Thermal hydraulics solver was already developed and now under testing of its stability and soundness. As a next step, interfacial and wall transport models was setup. In order to develop the best model and correlation package for the CAP code, various models currently used in major containment analysis codes, which are GOTHIC, CONTAIN2.0, and CONTEMPT-LT, have been reviewed. The origins of the selected models used in these codes have also been examined to find out if the models have not conflict with a proprietary right. In addition, a literature survey of the recent studies has been performed in order to incorporate the better models for the CAP code. The models and correlations of SPACE were also reviewed. CAP models and correlations are composed of interfacial heat/mass, and momentum transport models, and wall heat/mass, and momentum transport models. This paper discusses on those transport models in the CAP code.
Joint space-time geostatistical model for air quality surveillance
Russo, A.; Soares, A.; Pereira, M. J.
2009-04-01
Air pollution and peoples' generalized concern about air quality are, nowadays, considered to be a global problem. Although the introduction of rigid air pollution regulations has reduced pollution from industry and power stations, the growing number of cars on the road poses a new pollution problem. Considering the characteristics of the atmospheric circulation and also the residence times of certain pollutants in the atmosphere, a generalized and growing interest on air quality issues led to research intensification and publication of several articles with quite different levels of scientific depth. As most natural phenomena, air quality can be seen as a space-time process, where space-time relationships have usually quite different characteristics and levels of uncertainty. As a result, the simultaneous integration of space and time is not an easy task to perform. This problem is overcome by a variety of methodologies. The use of stochastic models and neural networks to characterize space-time dispersion of air quality is becoming a common practice. The main objective of this work is to produce an air quality model which allows forecasting critical concentration episodes of a certain pollutant by means of a hybrid approach, based on the combined use of neural network models and stochastic simulations. A stochastic simulation of the spatial component with a space-time trend model is proposed to characterize critical situations, taking into account data from the past and a space-time trend from the recent past. To identify near future critical episodes, predicted values from neural networks are used at each monitoring station. In this paper, we describe the design of a hybrid forecasting tool for ambient NO2 concentrations in Lisbon, Portugal.
Optimisation of Ionic Models to Fit Tissue Action Potentials: Application to 3D Atrial Modelling
Directory of Open Access Journals (Sweden)
Amr Al Abed
2013-01-01
Full Text Available A 3D model of atrial electrical activity has been developed with spatially heterogeneous electrophysiological properties. The atrial geometry, reconstructed from the male Visible Human dataset, included gross anatomical features such as the central and peripheral sinoatrial node (SAN, intra-atrial connections, pulmonary veins, inferior and superior vena cava, and the coronary sinus. Membrane potentials of myocytes from spontaneously active or electrically paced in vitro rabbit cardiac tissue preparations were recorded using intracellular glass microelectrodes. Action potentials of central and peripheral SAN, right and left atrial, and pulmonary vein myocytes were each fitted using a generic ionic model having three phenomenological ionic current components: one time-dependent inward, one time-dependent outward, and one leakage current. To bridge the gap between the single-cell ionic models and the gross electrical behaviour of the 3D whole-atrial model, a simplified 2D tissue disc with heterogeneous regions was optimised to arrive at parameters for each cell type under electrotonic load. Parameters were then incorporated into the 3D atrial model, which as a result exhibited a spontaneously active SAN able to rhythmically excite the atria. The tissue-based optimisation of ionic models and the modelling process outlined are generic and applicable to image-based computer reconstruction and simulation of excitable tissue.
Nechitailo, G.; Gordeev, A.
2004-01-01
The key role in increasing the resistance of plants to unfavorable space flight factors is assigned to biomembranes of root cells. It is these biomembranes in which numerous biochemical and biophysical processes determining the adaptive capacity of plant organisms occur. In the initial period of exposure to unfavorable space flight factors the adaptation reactions of the plant organism undoubtedly increase its resistance. But the intensification of removal of H + ions through the plasmalemma with an increase of the external influence sharply raises the quantity of cations leaving the cell, which leads to the accumulation of a considerable quantity of intracellular negative charges. These charges together with negative charges built in the membrane force protons to concentrate on the external surface of the membrane. Since protons have a very strong electric field, they form such a charge of which the electric field is about from several to hundreds of V/cm. The concentration of positive charges of protons entails the formation of a double electric field which extremely impedes the diffusion of other ions. Thus, a proton barrier is formed. Its length can be very considerable due to which the whole process of transmembrane energy and mass-transfer is disturbed. The proton barrier is easily destroyed by a weak electric field created in the root zone. In experiments on electrostimulation of different plants under space flight conditions at the orbital station MIR the absorption of nutrient elements by the root system increased to the optimal level, the ratio of physiologically active substances in the rhizosphere was normalized, the content of chlorophyll, carotin, and ascorbic acid in leaves corresponded to the ground-based control. Understanding of the mechanism of formation of a proton barrier on the plasmalemma of root cells as a result of the response of plants to the negative action of external factors (microgravity) is of great importance. It allows the
Data and models in Action. Methodological Issues in Production Ecology
Stein, A.; Penning, de F.W.T.
1999-01-01
This book addresses methodological issues of production ecology. A central issue is the combination of the agricultural model with reliable data in relation to scale. A model is developed with data from a single point, whereas decisions are to be made for areas of land. Such an approach requires the
Radiation Belt Environment Model: Application to Space Weather and Beyond
Fok, Mei-Ching H.
2011-01-01
Understanding the dynamics and variability of the radiation belts are of great scientific and space weather significance. A physics-based Radiation Belt Environment (RBE) model has been developed to simulate and predict the radiation particle intensities. The RBE model considers the influences from the solar wind, ring current and plasmasphere. It takes into account the particle drift in realistic, time-varying magnetic and electric field, and includes diffusive effects of wave-particle interactions with various wave modes in the magnetosphere. The RBE model has been used to perform event studies and real-time prediction of energetic electron fluxes. In this talk, we will describe the RBE model equation, inputs and capabilities. Recent advancement in space weather application and artificial radiation belt study will be discussed as well.
Modeling thermally active building components using space mapping
DEFF Research Database (Denmark)
Pedersen, Frank; Weitzmann, Peter; Svendsen, Svend
2005-01-01
In order to efficiently implement thermally active building components in new buildings, it is necessary to evaluate the thermal interaction between them and other building components. Applying parameter investigation or numerical optimization methods to a differential-algebraic (DAE) model....... This paper describes the principle of the space mapping technique, and introduces a simple space mapping technique. The technique is applied to a lumped parameter model of a thermo active component, which provides a model of the thermal performance of the component as a function of two design parameters...... of a building provides a systematic way of estimating efficient building designs. However, using detailed numerical calculations of the components in the building is a time consuming process, which may become prohibitive if the DAE model is to be used for parameter variation or optimization. Unfortunately...
Fast Filtering and Smoothing for Multivariate State Space Models
Koopman, S.J.M.; Durbin, J.
1998-01-01
This paper gives a new approach to diffuse filtering and smoothing for multivariate state space models. The standard approach treats the observations as vectors while our approach treats each element of the observational vector individually. This strategy leads to computationally efficient methods f
Magnetic Testing, and Modeling, Simulation and Analysis for Space Applications
Boghosian, Mary; Narvaez, Pablo; Herman, Ray
2012-01-01
The Aerospace Corporation (Aerospace) and Lockheed Martin Space Systems (LMSS) participated with Jet Propulsion Laboratory (JPL) in the implementation of a magnetic cleanliness program of the NASA/JPL JUNO mission. The magnetic cleanliness program was applied from early flight system development up through system level environmental testing. The JUNO magnetic cleanliness program required setting-up a specialized magnetic test facility at Lockheed Martin Space Systems for testing the flight system and a testing program with facility for testing system parts and subsystems at JPL. The magnetic modeling, simulation and analysis capability was set up and performed by Aerospace to provide qualitative and quantitative magnetic assessments of the magnetic parts, components, and subsystems prior to or in lieu of magnetic tests. Because of the sensitive nature of the fields and particles scientific measurements being conducted by the JUNO space mission to Jupiter, the imposition of stringent magnetic control specifications required a magnetic control program to ensure that the spacecraft's science magnetometers and plasma wave search coil were not magnetically contaminated by flight system magnetic interferences. With Aerospace's magnetic modeling, simulation and analysis and JPL's system modeling and testing approach, and LMSS's test support, the project achieved a cost effective approach to achieving a magnetically clean spacecraft. This paper presents lessons learned from the JUNO magnetic testing approach and Aerospace's modeling, simulation and analysis activities used to solve problems such as remnant magnetization, performance of hard and soft magnetic materials within the targeted space system in applied external magnetic fields.
Swales' Cars Model and the Metaphor of Research Space: An ...
African Journals Online (AJOL)
ANDCORPgh changing the world
following academics for reading through drafts of the paper and offering valuable ... The CARS (Create a Research Space) model for writing academic introductions ..... metaphysical and sometimes mystical or psychological experience of the poet, .... 'COVERT' STEP 3: [A lot has been written about the traditional music of.
Modeling irregularly spaced residual series as a continuous stochastic process
Von Asmuth, J.R.; Bierkens, M.F.P.
2005-01-01
In this paper, the background and functioning of a simple but effective continuous time approach for modeling irregularly spaced residual series is presented. The basic equations were published earlier by von Asmuth et al. (2002), who used them as part of a continuous time transfer function noise mo
The System of Occupations: Modeling Occupations in Sociodemographic Space.
Rotolo, Thomas; McPherson, J. Miller
2001-01-01
Analysis of the age and education composition of occupations in Current Population Survey Annual Demographic Files, 1972-82, supports an ecological model in which occupations compete for members in a shifting niche space defined by members' sociodemographic characteristics. In contrast, the movement of professions in the education dimension…
International Space Station Alpha (ISSA) Integrated Traffic Model
Gates, R. E.
1995-01-01
The paper discusses the development process of the International Space Station Alpha (ISSA) Integrated Traffic Model which is a subsystem analyses tool utilized in the ISSA design analysis cycles. Fast-track prototyping of the detailed relationships between daily crew and station consumables, propellant needs, maintenance requirements and crew rotation via spread sheets provide adequate benchmarks to assess cargo vehicle design and performance characteristics.
Inference and Decoding of Motor Cortex Low-Dimensional Dynamics via Latent State-Space Models.
Aghagolzadeh, Mehdi; Truccolo, Wilson
2016-02-01
Motor cortex neuronal ensemble spiking activity exhibits strong low-dimensional collective dynamics (i.e., coordinated modes of activity) during behavior. Here, we demonstrate that these low-dimensional dynamics, revealed by unsupervised latent state-space models, can provide as accurate or better reconstruction of movement kinematics as direct decoding from the entire recorded ensemble. Ensembles of single neurons were recorded with triple microelectrode arrays (MEAs) implanted in ventral and dorsal premotor (PMv, PMd) and primary motor (M1) cortices while nonhuman primates performed 3-D reach-to-grasp actions. Low-dimensional dynamics were estimated via various types of latent state-space models including, for example, Poisson linear dynamic system (PLDS) models. Decoding from low-dimensional dynamics was implemented via point process and Kalman filters coupled in series. We also examined decoding based on a predictive subsampling of the recorded population. In this case, a supervised greedy procedure selected neuronal subsets that optimized decoding performance. When comparing decoding based on predictive subsampling and latent state-space models, the size of the neuronal subset was set to the same number of latent state dimensions. Overall, our findings suggest that information about naturalistic reach kinematics present in the recorded population is preserved in the inferred low-dimensional motor cortex dynamics. Furthermore, decoding based on unsupervised PLDS models may also outperform previous approaches based on direct decoding from the recorded population or on predictive subsampling.
Action selection in growing state spaces: control of network structure growth
Thalmeier, Dominik; Gómez, Vicenç; Kappen, Hilbert J.
2017-01-01
The dynamical processes taking place on a network depend on its topology. Influencing the growth process of a network therefore has important implications on such dynamical processes. We formulate the problem of influencing the growth of a network as a stochastic optimal control problem in which a structural cost function penalizes undesired topologies. We approximate this control problem with a restricted class of control problems that can be solved using probabilistic inference methods. To deal with the increasing problem dimensionality, we introduce an adaptive importance sampling method for approximating the optimal control. We illustrate this methodology in the context of formation of information cascades, considering the task of influencing the structure of a growing conversation thread, as in Internet forums. Using a realistic model of growing trees, we show that our approach can yield conversation threads with better structural properties than the ones observed without control.
A Management Model for International Participation in Space Exploration Missions
George, Patrick J.; Pease, Gary M.; Tyburski, Timothy E.
2005-01-01
This paper proposes an engineering management model for NASA's future space exploration missions based on past experiences working with the International Partners of the International Space Station. The authors have over 25 years of combined experience working with the European Space Agency, Japan Aerospace Exploration Agency, Canadian Space Agency, Italian Space Agency, Russian Space Agency, and their respective contractors in the design, manufacturing, verification, and integration of their elements electric power system into the United States on-orbit segment. The perspective presented is one from a specific sub-system integration role and is offered so that the lessons learned from solving issues of technical and cultural nature may be taken into account during the formulation of international partnerships. Descriptions of the types of unique problems encountered relative to interactions between international partnerships are reviewed. Solutions to the problems are offered, taking into consideration the technical implications. Through the process of investigating each solution, the important and significant issues associated with working with international engineers and managers are outlined. Potential solutions are then characterized by proposing a set of specific methodologies to jointly develop spacecraft configurations that benefits all international participants, maximizes mission success and vehicle interoperability while minimizing cost.
Applying Model Based Systems Engineering to NASA's Space Communications Networks
Bhasin, Kul; Barnes, Patrick; Reinert, Jessica; Golden, Bert
2013-01-01
System engineering practices for complex systems and networks now require that requirement, architecture, and concept of operations product development teams, simultaneously harmonize their activities to provide timely, useful and cost-effective products. When dealing with complex systems of systems, traditional systems engineering methodology quickly falls short of achieving project objectives. This approach is encumbered by the use of a number of disparate hardware and software tools, spreadsheets and documents to grasp the concept of the network design and operation. In case of NASA's space communication networks, since the networks are geographically distributed, and so are its subject matter experts, the team is challenged to create a common language and tools to produce its products. Using Model Based Systems Engineering methods and tools allows for a unified representation of the system in a model that enables a highly related level of detail. To date, Program System Engineering (PSE) team has been able to model each network from their top-level operational activities and system functions down to the atomic level through relational modeling decomposition. These models allow for a better understanding of the relationships between NASA's stakeholders, internal organizations, and impacts to all related entities due to integration and sustainment of existing systems. Understanding the existing systems is essential to accurate and detailed study of integration options being considered. In this paper, we identify the challenges the PSE team faced in its quest to unify complex legacy space communications networks and their operational processes. We describe the initial approaches undertaken and the evolution toward model based system engineering applied to produce Space Communication and Navigation (SCaN) PSE products. We will demonstrate the practice of Model Based System Engineering applied to integrating space communication networks and the summary of its
Model Experiments for the Determination of Airflow in Large Spaces
DEFF Research Database (Denmark)
Nielsen, Peter V.
Model experiments are one of the methods used for the determination of airflow in large spaces. This paper will discuss the formation of the governing dimensionless numbers. It is shown that experiments with a reduced scale often will necessitate a fully developed turbulence level of the flow....... Details of the flow from supply openings are very important for the determination of room air distribution. It is in some cases possible to make a simplified supply opening for the model experiment....
Phase space analysis of some interacting Chaplygin gas models
Energy Technology Data Exchange (ETDEWEB)
Khurshudyan, M. [Academy of Sciences of Armenia, Institute for Physical Research, Ashtarak (Armenia); Tomsk State University of Control Systems and Radioelectronics, Laboratory for Theoretical Cosmology, Tomsk (Russian Federation); Tomsk State Pedagogical University, Department of Theoretical Physics, Tomsk (Russian Federation); Myrzakulov, R. [Eurasian National University, Eurasian International Center for Theoretical Physics, Astana (Kazakhstan)
2017-02-15
In this paper we discuss a phase space analysis of various interacting Chaplygin gas models in general relativity. Linear and nonlinear sign changeable interactions are considered. For each case appropriate late time attractors of field equations are found. The Chaplygin gas is one of the dark fluids actively considered in modern cosmology due to the fact that it is a joint model of dark energy and dark matter. (orig.)
Gu, Fei; Preacher, Kristopher J; Wu, Wei; Yung, Yiu-Fai
2014-01-01
Although the state space approach for estimating multilevel regression models has been well established for decades in the time series literature, it does not receive much attention from educational and psychological researchers. In this article, we (a) introduce the state space approach for estimating multilevel regression models and (b) extend the state space approach for estimating multilevel factor models. A brief outline of the state space formulation is provided and then state space forms for univariate and multivariate multilevel regression models, and a multilevel confirmatory factor model, are illustrated. The utility of the state space approach is demonstrated with either a simulated or real example for each multilevel model. It is concluded that the results from the state space approach are essentially identical to those from specialized multilevel regression modeling and structural equation modeling software. More importantly, the state space approach offers researchers a computationally more efficient alternative to fit multilevel regression models with a large number of Level 1 units within each Level 2 unit or a large number of observations on each subject in a longitudinal study.
Nonlinear state space model identification of synchronous generators
Energy Technology Data Exchange (ETDEWEB)
Dehghani, M.; Nikravesh, S.K.Y. [Electrical Engineering Department, Amirkabir University of Technology, Tehran (Iran)
2008-05-15
A method for identification of a synchronous generator is suggested in this paper. The method uses the theoretical relations of machine parameters and the Prony method to find the state space model of the system. Such models are useful for controller design and stability tests. The proposed identification method is applied to a third order model of a synchronous generator. In this study, the field voltage is considered as the input and the active output power and the rotor angle are considered as the outputs of the synchronous generator. Simulation results show good accuracy of the identified model. (author)
Space in multi-agent systems modelling spatial processes
Directory of Open Access Journals (Sweden)
Petr Rapant
2007-06-01
Full Text Available Need for modelling of spatial processes arise in the spehere of geoinformation systems in the last time. Some processes (espetially natural ones can be modeled by means of using external tools, e. g. for modelling of contaminant transport in the environment. But in the case of socio-economic processes suitable tools interconnected with GIS are still in quest of reserch and development. One of the candidate technologies are so called multi-agent systems. Their theory is developed quite well, but they lack suitable means for dealing with space. This article deals with this problem and proposes solution for the field of a road transport modelling.
Neuro-Space Mapping for Modeling Heterojunction Bipolar Transistor
Institute of Scientific and Technical Information of China (English)
Yan Shuxia; Cheng Qianfu; Wu Haifeng; Zhang Qijun
2015-01-01
A neuro-space mapping(Neuro-SM) for modeling heterojunction bipolar transistor(HBT) is presented, which can automatically modify the input signals of the given model by neural network. The novel Neuro-SM formu-lations for DC and small-signal simulation are proposed to obtain the mapping network. Simulation results show that the errors between Neuro-SM models and the accurate data are less than 1%, demonstrating that the accurcy of the proposed method is higher than those of the existing models.
Dynamical real space renormalization group applied to sandpile models.
Ivashkevich, E V; Povolotsky, A M; Vespignani, A; Zapperi, S
1999-08-01
A general framework for the renormalization group analysis of self-organized critical sandpile models is formulated. The usual real space renormalization scheme for lattice models when applied to nonequilibrium dynamical models must be supplemented by feedback relations coming from the stationarity conditions. On the basis of these ideas the dynamically driven renormalization group is applied to describe the boundary and bulk critical behavior of sandpile models. A detailed description of the branching nature of sandpile avalanches is given in terms of the generating functions of the underlying branching process.
Combined Hand Gesture — Speech Model for Human Action Recognition
Directory of Open Access Journals (Sweden)
Sheng-Tzong Cheng
2013-12-01
Full Text Available This study proposes a dynamic hand gesture detection technology to effectively detect dynamic hand gesture areas, and a hand gesture recognition technology to improve the dynamic hand gesture recognition rate. Meanwhile, the corresponding relationship between state sequences in hand gesture and speech models is considered by integrating speech recognition technology with a multimodal model, thus improving the accuracy of human behavior recognition. The experimental results proved that the proposed method can effectively improve human behavior recognition accuracy and the feasibility of system applications. Experimental results verified that the multimodal gesture-speech model provided superior accuracy when compared to the single modal versions.
Combined hand gesture--speech model for human action recognition.
Cheng, Sheng-Tzong; Hsu, Chih-Wei; Li, Jian-Pan
2013-12-12
This study proposes a dynamic hand gesture detection technology to effectively detect dynamic hand gesture areas, and a hand gesture recognition technology to improve the dynamic hand gesture recognition rate. Meanwhile, the corresponding relationship between state sequences in hand gesture and speech models is considered by integrating speech recognition technology with a multimodal model, thus improving the accuracy of human behavior recognition. The experimental results proved that the proposed method can effectively improve human behavior recognition accuracy and the feasibility of system applications. Experimental results verified that the multimodal gesture-speech model provided superior accuracy when compared to the single modal versions.
Rodent Models of Non-classical Progesterone Action Regulating Ovulation
Directory of Open Access Journals (Sweden)
Melinda A. Mittelman-Smith
2017-07-01
Full Text Available It is becoming clear that steroid hormones act not only by binding to nuclear receptors that associate with specific response elements in the nucleus but also by binding to receptors on the cell membrane. In this newly discovered manner, steroid hormones can initiate intracellular signaling cascades which elicit rapid effects such as release of internal calcium stores and activation of kinases. We have learned much about the translocation and signaling of steroid hormone receptors from investigations into estrogen receptor α, which can be trafficked to, and signal from, the cell membrane. It is now clear that progesterone (P4 can also elicit effects that cannot be exclusively explained by transcriptional changes. Similar to E2 and its receptors, P4 can initiate signaling at the cell membrane, both through progesterone receptor and via a host of newly discovered membrane receptors (e.g., membrane progesterone receptors, progesterone receptor membrane components. This review discusses the parallels between neurotransmitter-like E2 action and the more recently investigated non-classical P4 signaling, in the context of reproductive behaviors in the rodent.
Nongenomic actions of cortisol in the teleost lactotroph model
DEFF Research Database (Denmark)
Borski, Russell J; Tipsmark, Christian Kølbæk; Mita, M
2006-01-01
of the present study was to investigate the role of phospholipase C (PLC)-IP3 in mediating cortisol's actions. During 30 min and 4-hour incubation, chicken GnRH-II induces a 2-4 fold increase in PRL release from the tilapia pituitary. The stimulatory effect of cGnRH-II was reduced by cortisol, cortisol-21......-hemisuccinate (HEF) and its membrane impermeant analog, HEF-BSA. Since GnRH induces PRL release, in part, via activation of PLC this suggests that cortisol may rapidly inhibit GnRH-induced PRL release by suppressing PLC activity. We also found that cortisol rapidly inhibits IP3 accumulation in tilapia RPD under...... stimulation by angiotensin II, a factor known to exert its cellular effects through stimulation of the PLC-IP3 pathway. Further studies demonstrate that cortisol reduces PLC activity (measured by the hydrolysis of 3H-PIP2) in a dose dependent manner from crude tilapia lactotroph membrane preparations. SRIF...
Discrete state space modeling and control of nonlinear unknown systems.
Savran, Aydogan
2013-11-01
A novel procedure for integrating neural networks (NNs) with conventional techniques is proposed to design industrial modeling and control systems for nonlinear unknown systems. In the proposed approach, a new recurrent NN with a special architecture is constructed to obtain discrete-time state-space representations of nonlinear dynamical systems. It is referred as the discrete state-space neural network (DSSNN). In the DSSNN, the outputs of the hidden layer neurons of the DSSNN represent the system's (pseudo) state. The inputs are fed to output neurons and the delayed outputs of the hidden layer neurons are fed to their inputs via adjustable weights. The discrete state space model of the actual system is directly obtained by training the DSSNN with the input-output data. A training procedure based on the back-propagation through time (BPTT) algorithm is developed. The Levenberg-Marquardt (LM) method with a trust region approach is used to update the DSSNN weights. Linear state space models enable to use well developed conventional analysis and design techniques. Thus, building a linear model of a system has primary importance in industrial applications. Thus, a suitable linearization procedure is proposed to derive the linear state space model from the nonlinear DSSNN representation. The controllability, observability and stability properties are examined. The state feedback controllers are designed with both the linear quadratic regulator (LQR) and the pole placement techniques. The regulator and servo control problems are both addressed. A full order observer is also designed to estimate the state variables. The performance of the proposed procedure is demonstrated by applying for both single-input single-output (SISO) and multiple-input multiple-output (MIMO) nonlinear control problems. © 2013 ISA. Published by Elsevier Ltd. All rights reserved.
Motivation in action: A process model of L2 motivation
1998-01-01
As part of a long-term project aimed at designing classroom interventions to motivate language learners, we have searched for a motivation model that could serve as a theoretical basis for the methodological applications. We have found that none of the existing models we considered were entirely adequate for our purpose for three reasons: (1) they did not provide a sufficiently comprehensive and detailed summary of all the relevant motivational influences on classroom behaviour; (2) they tend...
Estimating parameters for generalized mass action models with connectivity information
Directory of Open Access Journals (Sweden)
Voit Eberhard O
2009-05-01
Full Text Available Abstract Background Determining the parameters of a mathematical model from quantitative measurements is the main bottleneck of modelling biological systems. Parameter values can be estimated from steady-state data or from dynamic data. The nature of suitable data for these two types of estimation is rather different. For instance, estimations of parameter values in pathway models, such as kinetic orders, rate constants, flux control coefficients or elasticities, from steady-state data are generally based on experiments that measure how a biochemical system responds to small perturbations around the steady state. In contrast, parameter estimation from dynamic data requires time series measurements for all dependent variables. Almost no literature has so far discussed the combined use of both steady-state and transient data for estimating parameter values of biochemical systems. Results In this study we introduce a constrained optimization method for estimating parameter values of biochemical pathway models using steady-state information and transient measurements. The constraints are derived from the flux connectivity relationships of the system at the steady state. Two case studies demonstrate the estimation results with and without flux connectivity constraints. The unconstrained optimal estimates from dynamic data may fit the experiments well, but they do not necessarily maintain the connectivity relationships. As a consequence, individual fluxes may be misrepresented, which may cause problems in later extrapolations. By contrast, the constrained estimation accounting for flux connectivity information reduces this misrepresentation and thereby yields improved model parameters. Conclusion The method combines transient metabolic profiles and steady-state information and leads to the formulation of an inverse parameter estimation task as a constrained optimization problem. Parameter estimation and model selection are simultaneously carried out
Saab, Rim; Tausch, Nicole; Spears, Russell; Cheung, Wing-Yee
2015-09-01
We examined predictors of collective action among bystander group members in solidarity with a disadvantaged group by extending the dual pathway model of collective action, which proposes one efficacy-based and one emotion-based path to collective action (Van Zomeren, Spears, Fischer, & Leach, 2004). Based on two proposed functions of social identity performance (Klein, Spears, & Reicher, 2007), we distinguished between the efficacy of collective action at consolidating the identity of a protest movement and its efficacy at achieving social change (political efficacy). We expected identity consolidation efficacy to positively predict collective action tendencies directly and indirectly via political efficacy. We also expected collective action tendencies to be positively predicted by moral outrage and by sympathy in response to disadvantaged outgroup's suffering. These hypotheses were supported in two surveys examining intentions to protest for Palestine in Britain (Study 1), and intentions to attend the June 4th vigil in Hong Kong to commemorate the Tiananmen massacre among a sample of Hong Kong citizens (Study 2). The contributions of these findings to research on the dual pathway model of collective action and the different functions of collective action are discussed.
Action-based Dynamical Modelling for the Milky Way Disk
Trick, Wilma H; Rix, Hans-Walter
2016-01-01
We present RoadMapping, a full-likelihood dynamical modelling machinery that aims to recover the Milky Way's (MW) gravitational potential from large samples of stars in the Galactic disk. RoadMapping models the observed positions and velocities of stars with a parametrized, three-integral distribution function (DF) in a parametrized axisymmetric potential. We investigate through differential test cases with idealized mock data how the breakdown of model assumptions and data properties affect constraints on the potential and DF. Our key results are: (i) If the MW's true potential is not included in the assumed model potential family, we can - in the axisymmetric case - still find a robust estimate for the potential, with only <~ 10% difference in surface density within |z| <= 1.1 kpc inside the observed volume. (ii) Modest systematic differences between the true and model DF are inconsequential. E.g, when binning stars to define sub-populations with simple DFs, binning errors do not affect the modelling ...
Multiple ontologies in action: composite annotations for biosimulation models.
Gennari, John H; Neal, Maxwell L; Galdzicki, Michal; Cook, Daniel L
2011-02-01
There now exists a rich set of ontologies that provide detailed semantics for biological entities of interest. However, there is not (nor should there be) a single source ontology that provides all the necessary semantics for describing biological phenomena. In the domain of physiological biosimulation models, researchers use annotations to convey semantics, and many of these annotations require the use of multiple reference ontologies. Therefore, we have developed the idea of composite annotations that access multiple ontologies to capture the physics-based meaning of model variables. These composite annotations provide the semantic expressivity needed to disambiguate the often-complex features of biosimulation models, and can be used to assist with model merging and interoperability. In this paper, we demonstrate the utility of composite annotations for model merging by describing their use within SemGen, our semantics-based model composition software. More broadly, if orthogonal reference ontologies are to meet their full potential, users need tools and methods to connect and link these ontologies. Our composite annotations and the SemGen tool provide one mechanism for leveraging multiple reference ontologies.
Wingate, Robert J.
2012-01-01
After the launch scrub of Space Shuttle mission STS-133 on November 5, 2010, large cracks were discovered in two of the External Tank intertank stringers. The NASA Marshall Space Flight Center, as managing center for the External Tank Project, coordinated the ensuing failure investigation and repair activities with several organizations, including the manufacturer, Lockheed Martin. To support the investigation, the Marshall Space Flight Center formed an ad-hoc stress analysis team to complement the efforts of Lockheed Martin. The team undertook six major efforts to analyze or test the structural behavior of the stringers. Extensive finite element modeling was performed to characterize the local stresses in the stringers near the region of failure. Data from a full-scale tanking test and from several subcomponent static load tests were used to confirm the analytical conclusions. The analysis and test activities of the team are summarized. The root cause of the stringer failures and the flight readiness rationale for the repairs that were implemented are discussed.
Space modeling with SolidWorks and NX
Duhovnik, Jože; Drešar, Primož
2015-01-01
Through a series of step-by-step tutorials and numerous hands-on exercises, this book aims to equip the reader with both a good understanding of the importance of space in the abstract world of engineers and the ability to create a model of a product in virtual space – a skill essential for any designer or engineer who needs to present ideas concerning a particular product within a professional environment. The exercises progress logically from the simple to the more complex; while SolidWorks or NX is the software used, the underlying philosophy is applicable to all modeling software. In each case, the explanation covers the entire procedure from the basic idea and production capabilities through to the real model; the conversion from 3D model to 2D manufacturing drawing is also clearly explained. Topics covered include modeling of prism, axisymmetric, symmetric, and sophisticated shapes; digitization of physical models using modeling software; creation of a CAD model starting from a physical model; free fo...
A Trusted Host's Authentication Access and Control Model Faced on User Action
Institute of Scientific and Technical Information of China (English)
ZHANG Miao; XU Guoai; HU Zhengming; YANG Yixian
2006-01-01
The conception of trusted network connection (TNC) is introduced, and the weakness of TNC to control user's action is analyzed. After this, the paper brings out a set of secure access and control model based on access, authorization and control, and related authentication protocol. At last the security of this model is analyzed. The model can improve TNC's security of user control and authorization.
State space modeling of Memristor-based Wien oscillator
Talukdar, Abdul Hafiz Ibne
2011-12-01
State space modeling of Memristor based Wien \\'A\\' oscillator has been demonstrated for the first time considering nonlinear ion drift in Memristor. Time dependant oscillating resistance of Memristor is reported in both state space solution and SPICE simulation which plausibly provide the basis of realizing parametric oscillation by Memristor based Wien oscillator. In addition to this part Memristor is shown to stabilize the final oscillation amplitude by means of its nonlinear dynamic resistance which hints for eliminating diode in the feedback network of conventional Wien oscillator. © 2011 IEEE.
Life sciences research in space: The requirement for animal models
Fuller, C. A.; Philips, R. W.; Ballard, R. W.
1987-01-01
Use of animals in NASA space programs is reviewed. Animals are needed because life science experimentation frequently requires long-term controlled exposure to environments, statistical validation, invasive instrumentation or biological tissue sampling, tissue destruction, exposure to dangerous or unknown agents, or sacrifice of the subject. The availability and use of human subjects inflight is complicated by the multiple needs and demands upon crew time. Because only living organisms can sense, integrate and respond to the environment around them, the sole use of tissue culture and computer models is insufficient for understanding the influence of the space environment on intact organisms. Equipment for spaceborne experiments with animals is described.
Space Object Tracking Method Based on a Snake Model
Zhan-wei, Xu; Xin, Wang
2016-04-01
In this paper, aiming at the problem of unstable tracking of low-orbit variable and bright space objects, adopting an active contour model, a kind of improved GVF (Gradient Vector Flow) - Snake algorithm is proposed to realize the real-time search of the real object contour on the CCD image. Combined with the Kalman filter for prediction, a new adaptive tracking method is proposed for space objects. Experiments show that this method can overcome the tracking error caused by the fixed window, and improve the tracking robustness.
A Model of Emergent Universe in Inhomogeneous Space-Time
Bhattacharya, Subhra
2016-01-01
A scenario of an emergent universe is constructed in the background of an inhomogeneous space-time model which is asymptotically (at spatial infinity) FRW space-time. The cosmic substratum consists of non-interacting two components, namely {\\bf a)} homogeneous and isotropic fluid but dissipative in nature and {\\bf b)} an inhomogeneous and anisotropic barotropic fluid. In non-equilibrium thermodynamic prescription (second order deviations), particle creation mechanism is considered the cause for the dissipative phenomena. It is found that for constant value of the particle creation rate parameter there exists a scenario of emergent universe.
Improving active space telescope wavefront control using predictive thermal modeling
Gersh-Range, Jessica; Perrin, Marshall D.
2015-01-01
Active control algorithms for space telescopes are less mature than those for large ground telescopes due to differences in the wavefront control problems. Active wavefront control for space telescopes at L2, such as the James Webb Space Telescope (JWST), requires weighing control costs against the benefits of correcting wavefront perturbations that are a predictable byproduct of the observing schedule, which is known and determined in advance. To improve the control algorithms for these telescopes, we have developed a model that calculates the temperature and wavefront evolution during a hypothetical mission, assuming the dominant wavefront perturbations are due to changes in the spacecraft attitude with respect to the sun. Using this model, we show that the wavefront can be controlled passively by introducing scheduling constraints that limit the allowable attitudes for an observation based on the observation duration and the mean telescope temperature. We also describe the implementation of a predictive controller designed to prevent the wavefront error (WFE) from exceeding a desired threshold. This controller outperforms simpler algorithms even with substantial model error, achieving a lower WFE without requiring significantly more corrections. Consequently, predictive wavefront control based on known spacecraft attitude plans is a promising approach for JWST and other future active space observatories.
State-space modeling to support management of brucellosis in the Yellowstone bison population
Hobbs, N. Thompson; Geremia, Chris; Treanor, John; Wallen, Rick; White, P.J.; Hooten, Mevin B.; Rhyan, Jack C.
2015-01-01
The bison (Bison bison) of the Yellowstone ecosystem, USA, exemplify the difficulty of conserving large mammals that migrate across the boundaries of conservation areas. Bison are infected with brucellosis (Brucella abortus) and their seasonal movements can expose livestock to infection. Yellowstone National Park has embarked on a program of adaptive management of bison, which requires a model that assimilates data to support management decisions. We constructed a Bayesian state-space model to reveal the influence of brucellosis on the Yellowstone bison population. A frequency-dependent model of brucellosis transmission was superior to a density-dependent model in predicting out-of-sample observations of horizontal transmission probability. A mixture model including both transmission mechanisms converged on frequency dependence. Conditional on the frequency-dependent model, brucellosis median transmission rate was 1.87 yr−1. The median of the posterior distribution of the basic reproductive ratio (R0) was 1.75. Seroprevalence of adult females varied around 60% over two decades, but only 9.6 of 100 adult females were infectious. Brucellosis depressed recruitment; estimated population growth rate λ averaged 1.07 for an infected population and 1.11 for a healthy population. We used five-year forecasting to evaluate the ability of different actions to meet management goals relative to no action. Annually removing 200 seropositive female bison increased by 30-fold the probability of reducing seroprevalence below 40% and increased by a factor of 120 the probability of achieving a 50% reduction in transmission probability relative to no action. Annually vaccinating 200 seronegative animals increased the likelihood of a 50% reduction in transmission probability by fivefold over no action. However, including uncertainty in the ability to implement management by representing stochastic variation in the number of accessible bison dramatically reduced the probability of
Self-similarity of phase-space networks of frustrated spin models and lattice gas models
Peng, Yi; Wang, Feng; Han, Yilong
2013-03-01
We studied the self-similar properties of the phase-spaces of two frustrated spin models and two lattice gas models. The frustrated spin models included (1) the anti-ferromagnetic Ising model on a two-dimensional triangular lattice (1a) at the ground states and (1b) above the ground states and (2) the six-vertex model. The two lattice gas models were (3) the one-dimensional lattice gas model and (4) the two-dimensional lattice gas model. The phase spaces were mapped to networks so that the fractal analysis of complex networks could be applied, i.e. the box-covering method and the cluster-growth method. These phase spaces, in turn, establish new classes of networks with unique self-similar properties. Models 1a, 2, and 3 with long-range power-law correlations in real space exhibit fractal phase spaces, while models 1b and 4 with short-range exponential correlations in real space exhibit nonfractal phase spaces. This behavior agrees with one of untested assumptions in Tsallis nonextensive statistics. Hong Kong GRC grants 601208 and 601911
Aquatic blues: modeling depression and antidepressant action in zebrafish.
Nguyen, Michael; Stewart, Adam Michael; Kalueff, Allan V
2014-12-01
Depression is a serious psychiatric condition affecting millions of patients worldwide. Unipolar depression is characterized by low mood, anhedonia, social withdrawal and other severely debilitating psychiatric symptoms. Bipolar disorder manifests in alternating depressed mood and 'hyperactive' manic/hypomanic states. Animal experimental models are an invaluable tool for research into the pathogenesis of bipolar/unipolar depression, and for the development of potential treatments. Due to their high throughput value, genetic tractability, low cost and quick reproductive cycle, zebrafish (Danio rerio) have emerged as a promising new model species for studying brain disorders. Here, we discuss the developing utility of zebrafish for studying depression disorders, and outline future areas of research in this field. We argue that zebrafish represent a useful model organism for studying depression and its behavioral, genetic and physiological mechanisms, as well as for anti-depressant drug discovery.
Mapping from Speech to Images Using Continuous State Space Models
DEFF Research Database (Denmark)
Lehn-Schiøler, Tue; Hansen, Lars Kai; Larsen, Jan
2005-01-01
In this paper a system that transforms speech waveforms to animated faces are proposed. The system relies on continuous state space models to perform the mapping, this makes it possible to ensure video with no sudden jumps and allows continuous control of the parameters in 'face space......'. The performance of the system is critically dependent on the number of hidden variables, with too few variables the model cannot represent data, and with too many overfitting is noticed. Simulations are performed on recordings of 3-5 sec.\\$\\backslash\\$ video sequences with sentences from the Timit database. From...... a subjective point of view the model is able to construct an image sequence from an unknown noisy speech sequence even though the number of training examples are limited....
A growing social network model in geographical space
Antonioni, Alberto; Tomassini, Marco
2017-09-01
In this work we propose a new model for the generation of social networks that includes their often ignored spatial aspects. The model is a growing one and links are created either taking space into account, or disregarding space and only considering the degree of target nodes. These two effects can be mixed linearly in arbitrary proportions through a parameter. We numerically show that for a given range of the combination parameter, and for given mean degree, the generated network class shares many important statistical features with those observed in actual social networks, including the spatial dependence of connections. Moreover, we show that the model provides a good qualitative fit to some measured social networks.
Stochastic modelling of dissolved inorganic nitrogen in space and time
DEFF Research Database (Denmark)
Lophaven, Søren Nymand; Carstensen, Niels Jacob; Rootzen, Helle
2006-01-01
Environmental monitoring datasets often contain a large amount of missing values, and are characterized as being sampled over time on a distinct number of locations in the area of interest. This paper proposes a stochastic approach for modelling such data in space and time, by taking the spatial...... and temporal correlations in data into account. It has been applied to observations of dissolved inorganic nitrogen in the Kattegat during the period 1993-1997. Modelling results are shown as maps of the spatial distribution of dissolved inorganic nitrogen (DIN) in 4 weeks, representing the four seasons......, and as time series of DIN at three different locations. However, the model approach could be applied to any space-time point given by a location in the Kattegat area and a week in the 5-year period 1993-1997. The results can be interpreted from a biological and physical point of view. Thus for the specific...
Action-Based Dynamical Modeling for the Milky Way Disk
Trick, Wilma H.; Bovy, Jo; Rix, Hans-Walter
2016-10-01
We present RoadMapping, a full-likelihood dynamical modeling machinery that aims to recover the Milky Way’s (MW) gravitational potential from large samples of stars in the Galactic disk. RoadMapping models the observed positions and velocities of stars with a parameterized, three-integral distribution function (DF) in a parameterized axisymmetric potential. We investigate through differential test cases with idealized mock data how the breakdown of model assumptions and data properties affect constraints on the potential and DF. Our key results are: (i) If the MW’s true potential is not included in the assumed model potential family, we can—in the axisymmetric case—still find a robust estimate for the potential, with only ≲ 10 % difference in surface density within | z| ≤slant 1.1 {kpc} inside the observed volume. (ii) Modest systematic differences between the true and model DF are inconsequential. E.g., when binning stars to define sub-populations with simple DFs, binning errors do not affect the modeling as long as the DF parameters of neighboring bins differ by \\lt 20 % . In addition, RoadMapping ensures unbiased potential estimates for either (iii) small misjudgements of the spatial selection function (i.e., ≲ 15 % at the survey volume’s edge), (iv) if distances are known to within 10%, or (v) if proper motion uncertainties are known within 10% or are smaller than δ μ ≲ 1 {mas} {{yr}}-1. Challenges are the rapidly increasing computational costs for large sample sizes. Overall, RoadMapping is well suited to making precise new measurements of the MW’s potential with data from the upcoming Gaia releases.
The importance of understanding: Model space moderates goal specificity effects.
Kistner, Saskia; Burns, Bruce D; Vollmeyer, Regina; Kortenkamp, Ulrich
2016-01-01
The three-space theory of problem solving predicts that the quality of a learner's model and the goal specificity of a task interact on knowledge acquisition. In Experiment 1 participants used a computer simulation of a lever system to learn about torques. They either had to test hypotheses (nonspecific goal), or to produce given values for variables (specific goal). In the good- but not in the poor-model condition they saw torque depicted as an area. Results revealed the predicted interaction. A nonspecific goal only resulted in better learning when a good model of torques was provided. In Experiment 2 participants learned to manipulate the inputs of a system to control its outputs. A nonspecific goal to explore the system helped performance when compared to a specific goal to reach certain values when participants were given a good model, but not when given a poor model that suggested the wrong hypothesis space. Our findings support the three-space theory. They emphasize the importance of understanding for problem solving and stress the need to study underlying processes.
Space physiology IV: mathematical modeling of the cardiovascular system in space exploration.
Keith Sharp, M; Batzel, Jerry Joseph; Montani, Jean-Pierre
2013-08-01
Mathematical modeling represents an important tool for analyzing cardiovascular function during spaceflight. This review describes how modeling of the cardiovascular system can contribute to space life science research and illustrates this process via modeling efforts to study postflight orthostatic intolerance (POI), a key issue for spaceflight. Examining this application also provides a context for considering broader applications of modeling techniques to the challenges of bioastronautics. POI, which affects a large fraction of astronauts in stand tests upon return to Earth, presents as dizziness, fainting and other symptoms, which can diminish crew performance and cause safety hazards. POI on the Moon or Mars could be more critical. In the field of bioastronautics, POI has been the dominant application of cardiovascular modeling for more than a decade, and a number of mechanisms for POI have been investigated. Modeling approaches include computational models with a range of incorporated factors and hemodynamic sophistication, and also physical models tested in parabolic and orbital flight. Mathematical methods such as parameter sensitivity analysis can help identify key system mechanisms. In the case of POI, this could lead to more effective countermeasures. Validation is a persistent issue in modeling efforts, and key considerations and needs for experimental data to synergistically improve understanding of cardiovascular responses are outlined. Future directions in cardiovascular modeling include subject-specific assessment of system status, as well as research on integrated physiological responses, leading, for instance, to assessment of subject-specific susceptibility to POI or effects of cardiovascular alterations on muscular, vision and cognitive function.
Nonlinear sigma models with compact hyperbolic target spaces
Energy Technology Data Exchange (ETDEWEB)
Gubser, Steven [Joseph Henry Laboratories, Princeton University, Princeton, NJ 08544 (United States); Saleem, Zain H. [Department of Physics and Astronomy, University of Pennsylvania,Philadelphia, PA 19104 (United States); National Center for Physics, Quaid-e-Azam University Campus,Islamabad 4400 (Pakistan); Schoenholz, Samuel S. [Department of Physics and Astronomy, University of Pennsylvania,Philadelphia, PA 19104 (United States); Stoica, Bogdan [Walter Burke Institute for Theoretical Physics, California Institute of Technology,452-48, Pasadena, CA 91125 (United States); Stokes, James [Department of Physics and Astronomy, University of Pennsylvania,Philadelphia, PA 19104 (United States)
2016-06-23
We explore the phase structure of nonlinear sigma models with target spaces corresponding to compact quotients of hyperbolic space, focusing on the case of a hyperbolic genus-2 Riemann surface. The continuum theory of these models can be approximated by a lattice spin system which we simulate using Monte Carlo methods. The target space possesses interesting geometric and topological properties which are reflected in novel features of the sigma model. In particular, we observe a topological phase transition at a critical temperature, above which vortices proliferate, reminiscent of the Kosterlitz-Thouless phase transition in the O(2) model V.L. Berezinskii, Destruction of long-range order in one-dimensional and two-dimensional systems having a continuous symmetry group II. Quantum systems, Sov. Phys. JETP 34 (1972) 610. J.M. Kosterlitz and D.J. Thouless, Ordering, metastability and phase transitions in two-dimensional systems, J. Phys. C 6 (1973) 1181 [http://inspirehep.net/search?p=find+J+%22J.Phys.,C6,1181%22]. . Unlike in the O(2) case, there are many different types of vortices, suggesting a possible analogy to the Hagedorn treatment of statistical mechanics of a proliferating number of hadron species. Below the critical temperature the spins cluster around six special points in the target space known as Weierstrass points. The diversity of compact hyperbolic manifolds suggests that our model is only the simplest example of a broad class of statistical mechanical models whose main features can be understood essentially in geometric terms.
Community Reintegration: The Value of Educational-Action-Training Models.
Versluys, Hilda P.
1984-01-01
The article describes the principles that guide program development, the use of therapeutic and educational activities, and the components of transitional program models for disabled individuals re-entering the community following discharge from rehabilitation facilities. The role of the occupatonal therapist in successful reintegration is…
Modelling human actions on lightweight structures: experimental and numerical developments
Directory of Open Access Journals (Sweden)
Živanović S.
2015-01-01
Full Text Available This paper presents recent, numerical and experimental, developments in modelling dynamic loading generated by humans. As modern structures with exposure to human-induced loading, such as footbridges, building floors and grandstands, are becoming ever lighter and more slender, they are increasingly susceptible to vibration under human-induced dynamic excitation, such as walking, jumping, running and bobbing, and their vibration serviceability assessment is often a deciding factor in the design process. While simplified modelling of the human using a harmonic force was sufficient for assessment of vibration performance of more robust structures a few decades ago, the higher fidelity models are required in the contemporary design. These models are expected not only to describe both temporal and spectral features of the force signal more accurately, but also to capture the influence, psychological and physiological, of human-structure and human-human interaction mechanisms on the human kinematics, and consequently on the force generated and the resulting vibration response. Significant advances have been made in both the research studies and design guidance. This paper reports the key developments and identifies the scope for further research.
Modeling action potential generation and propagation in NRK fibroblasts
Torres, J.J.; Cornelisse, L.N.; Harks, E.G.; Meerwijk, W.P. van; Theuvenet, A.P.R.; Ypey, D.L.
2004-01-01
Normal rat kidney (NRK) fibroblasts change their excitability properties through the various stages of cell proliferation. The present mathematical model has been developed to explain excitability of quiescent (serum deprived) NRK cells. It includes as cell membrane components, on the basis of patch
Estimation of musculoskeletal models from in situ measurements of muscle action in the rat hindlimb.
Yeo, Sang Hoon; Mullens, Christopher H; Sandercock, Thomas G; Pai, Dinesh K; Tresch, Matthew C
2011-03-01
Musculoskeletal models are often created by making detailed anatomical measurements of muscle properties. These measurements can then be used to determine the parameters of canonical models of muscle action. We describe here a complementary approach for developing and validating muscle models, using in situ measurements of muscle actions. We characterized the actions of two rat hindlimb muscles: the gracilis posticus (GRp) and the posterior head of biceps femoris (BFp; excluding the anterior head with vertebral origin). The GRp is a relatively simple muscle, with a circumscribed origin and insertion. The BFp is more complex, with an insertion distributed along the tibia. We measured the six-dimensional isometric forces and moments at the ankle evoked from stimulating each muscle at a range of limb configurations. The variation of forces and moments across the workspace provides a succinct characterization of muscle action. We then used this data to create a simple muscle model with a single point insertion and origin. The model parameters were optimized to best explain the observed force-moment data. This model explained the relatively simple muscle, GRp, very well (R(2)>0.85). Surprisingly, this simple model was also able to explain the action of the BFp, despite its greater complexity (R(2)>0.84). We then compared the actions observed here with those predicted using recently published anatomical measurements. Although the forces and moments predicted for the GRp were very similar to those observed here, the predictions for the BFp differed. These results show the potential utility of the approach described here for the development and refinement of musculoskeletal models based on in situ measurements of muscle actions.
Foresight Model of Turkey's Defense Industries' Space Studies until 2040
Yuksel, Nurdan; Cifci, Hasan; Cakir, Serhat
2016-07-01
Being advanced in science and technology is inevitable reality in order to be able to have a voice in the globalized world. Therefore, for the countries, making policies in consistent with their societies' intellectual, economic and political infrastructure and attributing them to the vision having been embraced by all parties of the society is quite crucial for the success. The generated policies are supposed to ensure the usage of countries' resources in the most effective and fastest way, determine the priorities and needs of society and set their goals and related roadmaps. In this sense, technology foresight studies based on justified forecasting in science and technology have critical roles in the process of developing policies. In this article, Foresight Model of Turkey's Defense Industries' Space Studies, which is turned out to be the important part of community life and fundamental background of most technologies, up to 2040 is presented. Turkey got late in space technology studies. Hence, for being fast and efficient to use its national resources in a cost effective way and within national and international collaboration, it should be directed to its pre-set goals. By taking all these factors into consideration, the technology foresight model of Turkey's Defense Industry's Space Studies was presented in the study. In the model, the present condition of space studies in the World and Turkey was analyzed; literature survey and PEST analysis were made. PEST analysis will be the inputs of SWOT analysis and Delphi questionnaire will be used in the study. A two-round Delphi survey will be applied to the participants from universities, public and private organizations operating in space studies at Defense Industry. Critical space technologies will be distinguished according to critical technology measures determined by expert survey; space technology fields and goals will be established according to their importance and feasibility indexes. Finally, for the
Computational Model of Primary Visual Cortex Combining Visual Attention for Action Recognition.
Directory of Open Access Journals (Sweden)
Na Shu
Full Text Available Humans can easily understand other people's actions through visual systems, while computers cannot. Therefore, a new bio-inspired computational model is proposed in this paper aiming for automatic action recognition. The model focuses on dynamic properties of neurons and neural networks in the primary visual cortex (V1, and simulates the procedure of information processing in V1, which consists of visual perception, visual attention and representation of human action. In our model, a family of the three-dimensional spatial-temporal correlative Gabor filters is used to model the dynamic properties of the classical receptive field of V1 simple cell tuned to different speeds and orientations in time for detection of spatiotemporal information from video sequences. Based on the inhibitory effect of stimuli outside the classical receptive field caused by lateral connections of spiking neuron networks in V1, we propose surround suppressive operator to further process spatiotemporal information. Visual attention model based on perceptual grouping is integrated into our model to filter and group different regions. Moreover, in order to represent the human action, we consider the characteristic of the neural code: mean motion map based on analysis of spike trains generated by spiking neurons. The experimental evaluation on some publicly available action datasets and comparison with the state-of-the-art approaches demonstrate the superior performance of the proposed model.
The Use of Evolution in a Central Action Selection Model
Directory of Open Access Journals (Sweden)
F. Montes-Gonzalez
2007-01-01
Full Text Available The use of effective central selection provides flexibility in design by offering modularity and extensibility. In earlier papers we have focused on the development of a simple centralized selection mechanism. Our current goal is to integrate evolutionary methods in the design of non-sequential behaviours and the tuning of specific parameters of the selection model. The foraging behaviour of an animal robot (animat has been modelled in order to integrate the sensory information from the robot to perform selection that is nearly optimized by the use of genetic algorithms. In this paper we present how selection through optimization finally arranges the pattern of presented behaviours for the foraging task. Hence, the execution of specific parts in a behavioural pattern may be ruled out by the tuning of these parameters. Furthermore, the intensive use of colour segmentation from a colour camera for locating a cylinder sets a burden on the calculations carried out by the genetic algorithm.
A conceptual model for translating omic data into clinical action
Directory of Open Access Journals (Sweden)
Timothy M Herr
2015-01-01
Full Text Available Genomic, proteomic, epigenomic, and other "omic" data have the potential to enable precision medicine, also commonly referred to as personalized medicine. The volume and complexity of omic data are rapidly overwhelming human cognitive capacity, requiring innovative approaches to translate such data into patient care. Here, we outline a conceptual model for the application of omic data in the clinical context, called "the omic funnel." This model parallels the classic "Data, Information, Knowledge, Wisdom pyramid" and adds context for how to move between each successive layer. Its goal is to allow informaticians, researchers, and clinicians to approach the problem of translating omic data from bench to bedside, by using discrete steps with clearly defined needs. Such an approach can facilitate the development of modular and interoperable software that can bring precision medicine into widespread practice.
A phase-space model for Pleistocene ice volume
Imbrie, John Z; Lisiecki, Lorraine E
2011-01-01
We present a phase-space model that simulates Pleistocene ice volume changes based on Earth's orbital parameters. Terminations in the model are triggered by a combination of ice volume and orbital forcing and agree well with age estimates for Late Pleistocene terminations. The average phase at which model terminations begin is approximately 90 +/- 90 degrees before the maxima in all three orbital cycles. The large variability in phase is likely caused by interactions between the three cycles and ice volume. Unlike previous ice volume models, this model produces an orbitally driven increase in 100-kyr power during the mid-Pleistocene transition without any change in model parameters. This supports the hypothesis that Pleistocene variations in the 100-kyr power of glacial cycles could be caused, at least in part, by changes in Earth's orbital parameters, such as amplitude modulation of the 100-kyr eccentricity cycle, rather than changes within the climate system.
The Perception-Action Model: Counting Computational Mechanisms
DEFF Research Database (Denmark)
Grünbaum, Thor
2016-01-01
of these current discussions and argue that PAM is ambiguous between a strong and a weak version. I argue that, given a standard way of individuating computational mechanisms, the available evidence cannot be used to distinguish between these versions. This not only has consequences for philosophical theories...... of the role of visual consciousness but also has implications for the role of experimental evidence in model testing in cognitive neuroscience....
Molecular model of the action potential sodium channel.
Guy, H R; Seetharamulu, P
1986-01-01
Secondary and tertiary structural models of sodium channel transmembrane segments were developed from its recently determined primary sequence in Electrophorus electricus. The model has four homologous domains, and each domain has eight homologous transmembrane segments, S1 through S8. Each domain contains three relatively apolar segments (S1, S2 and S3) and two very apolar segments (S5 and S8), all postulated to be transmembrane alpha-helices. S4 segments have positively charged residues, mainly arginines, at every third residue. The model channel lining is formed by four S4 transmembrane alpha-helices and four negatively charged S7 segments. S7 segments are postulated to be short, partially transmembrane amphipathic alpha-helices in three domains and a beta-strand in the last domain. S7 segments are preceded by short apolar segments (S6) postulated to be alpha-helices in three domains and a beta-strand in the last domain. Positively charged side chains of S4 form salt bridges with negatively charged side chains on S7 and near the ends of S1 and S3. Putative extracellular segments that contain 5 of the 10 potential N-glycosylation sites link S5 to S6. Channel activation may involve a 'helical screw' mechanism in which S4 helices rotate around their axes as they move toward the extracellular surface. Images PMID:2417247
Acoustic Predictions in Industrial Spaces Using a Diffusion Model
Directory of Open Access Journals (Sweden)
Alexis Billon
2012-01-01
Full Text Available Industrial spaces are known to be very noisy working environment. This noise exposure can be uncomfortable, tiring, or even harmful, at worst. Industrial spaces have several characteristics: they are often huge flat volumes fitted with many obstacles and sound sources. Moreover, they are usually surrounded by rooms where low noise levels are required. The existing prediction tools can seldom model all these phenomena accurately. In this paper, a prediction model based on a diffusion equation is presented. The successive developments carried out to deal with the various propagating phenomena met in industrial spaces are shown. For each phenomenon, numerical or experimental examples are given to highlight the validity of this model. It is also shown that its computation load is very little in comparison to ray-tracing-based methods. In addition, this model can be used as a reliable and flexible tool to study the physics of the coupling between rooms. Finally, an application to a virtual factory is presented.
Discrete random walk models for space-time fractional diffusion
Energy Technology Data Exchange (ETDEWEB)
Gorenflo, Rudolf; Mainardi, Francesco; Moretti, Daniele; Pagnini, Gianni; Paradisi, Paolo
2002-11-01
A physical-mathematical approach to anomalous diffusion may be based on generalized diffusion equations (containing derivatives of fractional order in space or/and time) and related random walk models. By space-time fractional diffusion equation we mean an evolution equation obtained from the standard linear diffusion equation by replacing the second-order space derivative with a Riesz-Feller derivative of order {alpha} is part of (0,2] and skewness {theta} (module{theta}{<=}{l_brace}{alpha},2-{alpha}{r_brace}), and the first-order time derivative with a Caputo derivative of order {beta} is part of (0,1]. Such evolution equation implies for the flux a fractional Fick's law which accounts for spatial and temporal non-locality. The fundamental solution (for the Cauchy problem) of the fractional diffusion equation can be interpreted as a probability density evolving in time of a peculiar self-similar stochastic process that we view as a generalized diffusion process. By adopting appropriate finite-difference schemes of solution, we generate models of random walk discrete in space and time suitable for simulating random variables whose spatial probability density evolves in time according to this fractional diffusion equation.
Nuclear model calculations and their role in space radiation research
Townsend, L. W.; Cucinotta, F. A.; Heilbronn, L. H.
2002-01-01
Proper assessments of spacecraft shielding requirements and concomitant estimates of risk to spacecraft crews from energetic space radiation requires accurate, quantitative methods of characterizing the compositional changes in these radiation fields as they pass through thick absorbers. These quantitative methods are also needed for characterizing accelerator beams used in space radiobiology studies. Because of the impracticality/impossibility of measuring these altered radiation fields inside critical internal body organs of biological test specimens and humans, computational methods rather than direct measurements must be used. Since composition changes in the fields arise from nuclear interaction processes (elastic, inelastic and breakup), knowledge of the appropriate cross sections and spectra must be available. Experiments alone cannot provide the necessary cross section and secondary particle (neutron and charged particle) spectral data because of the large number of nuclear species and wide range of energies involved in space radiation research. Hence, nuclear models are needed. In this paper current methods of predicting total and absorption cross sections and secondary particle (neutrons and ions) yields and spectra for space radiation protection analyses are reviewed. Model shortcomings are discussed and future needs presented. c2002 COSPAR. Published by Elsevier Science Ltd. All right reserved.
Dispersion modeling of thermal power plant emissions on stochastic space
Gorle, J. M. R.; Sambana, N. R.
2016-05-01
This study aims to couple a deterministic atmospheric dispersion solver based on Gaussian model with a nonintrusive stochastic model to quantify the propagation of multiple uncertainties. The nonintrusive model is based on probabilistic collocation framework. The advantage of nonintrusive nature is to retain the existing deterministic plume dispersion model without missing the accuracy in extracting the statistics of stochastic solution. The developed model is applied to analyze the SO2 emission released from coal firing unit in the second stage of the National Thermal Power Corporation (NTPC) in Dadri, India using "urban" conditions. The entire application is split into two cases, depending on the source of uncertainty. In case 1, the uncertainties in stack gas exit conditions are used to construct the stochastic space while in case 2, meteorological conditions are considered as the sources of uncertainty. Both cases develop 2D uncertain random space in which the uncertainty propagation is quantified in terms of plume rise and pollutant concentration distribution under slightly unstable atmospheric stability conditions. Starting with deterministic Gaussian plume model demonstration and its application, development of stochastic collocation model, convergence study, error analysis, and uncertainty quantification are presented in this paper.
Learning Continuous Action Models in a Real-Time Strategy Environment
2008-01-01
method for reasoning with continuous action spaces. Santamaria et al. (1997) also ex- amined integrated CBR/RL approaches that operate on...game tactics through evolu- tionary learning. AI Magazine, 27(3), 75-84. Ram, A., & Santamaria , J.C. (1997). Continuous case-based rea- soning...Computational Intelligence in Games. Hawaii, HO: IEEE. Santamaria , J.C., Sutton, R., & Ram, A. (1998). Experiments with reinforcement learning in
Modeling Ships and Space Craft The Science and Art of Mastering the Oceans and Sky
Hagler, Gina
2013-01-01
Modeling Ships and Space Craft: The Science and Art of Mastering the Oceans and Sky begins with the theories of Aristotle and Archimedes, moving on to examine the work of Froude and Taylor, the early aviators and the Wright Brothers, Goddard and the other rocket men, and the computational fluid dynamic models of our time. It examines the ways each used fluid dynamic principles in the design of their vessels. In the process, this book covers the history of hydrodynamic (aero and fluid) theory and its progression – with some very accessible science examples – including seminal theories. Hydrodynamic principles in action are also explored with examples from nature and the works of man. This is a book for anyone interested in the history of technology – specifically the methods and science behind the use of scale models and hydrodynamic principles in the marine and aeronautical designs of today.
Transformation of Neural State Space Models into LFT Models for Robust Control Design
DEFF Research Database (Denmark)
Bendtsen, Jan Dimon; Trangbæk, Klaus
2000-01-01
This paper considers the extraction of linear state space models and uncertainty models from neural networks trained as state estimators with direct application to robust control. A new method for writing a neural state space model in a linear fractional transformation form in a non-conservative ......This paper considers the extraction of linear state space models and uncertainty models from neural networks trained as state estimators with direct application to robust control. A new method for writing a neural state space model in a linear fractional transformation form in a non......-conservative way is proposed, and it is demonstrated how a standard robust control law can be designed for a system described by means of a multi layer perceptron....
Efficient parameterization of cardiac action potential models using a genetic algorithm
Cairns, Darby I.; Fenton, Flavio H.; Cherry, E. M.
2017-09-01
Finding appropriate values for parameters in mathematical models of cardiac cells is a challenging task. Here, we show that it is possible to obtain good parameterizations in as little as 30-40 s when as many as 27 parameters are fit simultaneously using a genetic algorithm and two flexible phenomenological models of cardiac action potentials. We demonstrate how our implementation works by considering cases of "model recovery" in which we attempt to find parameter values that match model-derived action potential data from several cycle lengths. We assess performance by evaluating the parameter values obtained, action potentials at fit and non-fit cycle lengths, and bifurcation plots for fidelity to the truth as well as consistency across different runs of the algorithm. We also fit the models to action potentials recorded experimentally using microelectrodes and analyze performance. We find that our implementation can efficiently obtain model parameterizations that are in good agreement with the dynamics exhibited by the underlying systems that are included in the fitting process. However, the parameter values obtained in good parameterizations can exhibit a significant amount of variability, raising issues of parameter identifiability and sensitivity. Along similar lines, we also find that the two models differ in terms of the ease of obtaining parameterizations that reproduce model dynamics accurately, most likely reflecting different levels of parameter identifiability for the two models.
Latent state-space models for neural decoding.
Aghagolzadeh, Mehdi; Truccolo, Wilson
2014-01-01
Ensembles of single-neurons in motor cortex can show strong low-dimensional collective dynamics. In this study, we explore an approach where neural decoding is applied to estimated low-dimensional dynamics instead of to the full recorded neuronal population. A latent state-space model (SSM) approach is used to estimate the low-dimensional neural dynamics from the measured spiking activity in population of neurons. A second state-space model representation is then used to decode kinematics, via a Kalman filter, from the estimated low-dimensional dynamics. The latent SSM-based decoding approach is illustrated on neuronal activity recorded from primary motor cortex in a monkey performing naturalistic 3-D reach and grasp movements. Our analysis show that 3-D reach decoding performance based on estimated low-dimensional dynamics is comparable to the decoding performance based on the full recorded neuronal population.
Joint Dynamics Modeling and Parameter Identification for Space Robot Applications
Directory of Open Access Journals (Sweden)
Adenilson R. da Silva
2007-01-01
Full Text Available Long-term mission identification and model validation for in-flight manipulator control system in almost zero gravity with hostile space environment are extremely important for robotic applications. In this paper, a robot joint mathematical model is developed where several nonlinearities have been taken into account. In order to identify all the required system parameters, an integrated identification strategy is derived. This strategy makes use of a robust version of least-squares procedure (LS for getting the initial conditions and a general nonlinear optimization method (MCS—multilevel coordinate search—algorithm to estimate the nonlinear parameters. The approach is applied to the intelligent robot joint (IRJ experiment that was developed at DLR for utilization opportunity on the International Space Station (ISS. The results using real and simulated measurements have shown that the developed algorithm and strategy have remarkable features in identifying all the parameters with good accuracy.
State Space Modelling and Data Analysis Exercises in LISA Pathfinder
Nofrarias, M.; Antonucci, F.; Armano, M.; Audley, H.; Auger, G.; Benedetti, M.; Binetruy, P.; Bogenstahl, J.; Bortoluzzi, D.; Brandt, N.; Caleno, M.; Cavalleri, A.; Congedo, G.; Cruise, M.; Danzmann, K.; De Marchi, F.; Diaz-Aguilo, M.; Diepholz, I.; Dixon, G.; Dolesi, R.; Dunbar, N.; Fauste, J.; Ferraioli, L.; Ferroni, V.; Fichter, W.; Fitzsimons, E.; Freschi, M.; García Marirrodriga, C.; Gerndt, R.; Gesa, L.; Gibert, F.; Giardini, D.; Grimani, C.; Grynagier, A.; Guzmán, F.; Harrison, I.; Heinzel, G.; Hewitson, M.; Hollington, D.; Hoyland, D.; Hueller, M.; Huesler, J.; Jennrich, O.; Jetzer, P.; Johlander, B.; Karnesis, N.; Korsakova, N.; Killow, C.; Llamas, X.; Lloro, I.; Lobo, A.; Maarschalkerweerd, R.; Madden, S.; Mance, D.; Martin, V.; Mateos, I.; McNamara, P.; Mendes, J.; Mitchell, E.; Nicolodi, D.; Perreur-Lloyd, M.; Plagnol, E.; Prat, P.; Ramos-Castro, J.; Reiche, J.; Romera Perez, J. A.; Robertson, D.; Rozemeijer, H.; Russano, G.; Schleicher, A.; Shaul, D.; Sopuerta, C. F.; Sumner, T. J.; Taylor, A.; Texier, D.; Trenkel, C.; Tu, H. B.; Vitale, S.; Wanner, G.; Ward, H.; Waschke, S.; Wass, P.; Wealthy, D.; Wen, S.; Weber, W.; Ziegler, T.; Zweifel, P.
2013-01-01
LISA Pathfinder is a mission planned by the European Space Agency (ESA) to test the key technologies that will allow the detection of gravitational waves in space. The instrument on-board, the LISA Technology package, will undergo an exhaustive campaign of calibrations and noise characterisation campaigns in order to fully describe the noise model. Data analysis plays an important role in the mission and for that reason the data analysis team has been developing a toolbox which contains all the functionality required during operations. In this contribution we give an overview of recent activities, focusing on the improvements in the modelling of the instrument and in the data analysis campaigns performed both with real and simulated data.
State space modelling and data analysis exercises in LISA Pathfinder
Nofrarias, M; Armano, M; Audley, H; Auger, G; Benedetti, M; Binetruy, P; Bogenstahl, J; Bortoluzzi, D; Bosetti, P; Brandt, N; Caleno, M; Cañizares, P; Cavalleri, A; Cesa, M; Chmeissani, M; Conchillo, A; Congedo, G; Cristofolin, I; Cruise, M; Danzmann, K; De Marchi, F; Diaz-Aguilo, M; Diepholz, I; Dixon, G; Dolesi, R; Dunbar, N; Fauste, J; Ferraioli, L; Fichter, V Ferroni W; Fitzsimons, E; Freschi, M; Marin, A García; Marirrodriga, C García; Gesa, R Gerndt L; Gibert, F; Giardini, D; Grimani, C; Grynagier, A; Guillaume, B; Guzmán, F; Harrison, I; Heinzel, G; Hernández, V; Hewitson, M; Hollington, D; Hough, J; Hoyland, D; Hueller, M; Huesler, J; Jennrich, O; Jetzer, P; Johlander, B; Killow, C; Llamas, X; Lloro, I; Lobo, A; Maarschalkerweerd, R; Madden, S; Mance, D; Mateos, I; McNamara, P W; Mendes, J; Mitchell, E; Monsky, A; Nicolini, D; Nicolodi, D; Pedersen, F; Perreur-Lloyd, M; Plagnol, E; Prat, P; Racca, G D; Ramos-Castro, J; Reiche, J; Perez, J A Romera; Robertson, D; Rozemeijer, H; Sanjuan, J; Schleicher, A; Schulte, M; Shaul, D; Stagnaro, L; Strandmoe, S; Steier, F; Sumner, T J; Taylor, A; Texier, D; Trenkel, C; Vitale, H-B Tu S; Wanner, G; Ward, H; Waschke, S; Wass, P; Weber, W J; Ziegler, T; Zweifel, P
2013-01-01
LISA Pathfinder is a mission planned by the European Space Agency to test the key technologies that will allow the detection of gravitational waves in space. The instrument on-board, the LISA Technology package, will undergo an exhaustive campaign of calibrations and noise characterisation campaigns in order to fully describe the noise model. Data analysis plays an important role in the mission and for that reason the data analysis team has been developing a toolbox which contains all the functionalities required during operations. In this contribution we give an overview of recent activities, focusing on the improvements in the modelling of the instrument and in the data analysis campaigns performed both with real and simulated data.
Dynamical 3-Space Gravity Theory: Effects on Polytropic Solar Models
Directory of Open Access Journals (Sweden)
Cahill R. T.
2011-01-01
Full Text Available Numerous experiments and observations have confirmed the existence of a dynamical 3-space, detectable directly by light-speed anisotropy experiments, and indirectly by means of novel gravitational effects, such as bore hole g-anomalies, predictable black hole masses, flat spiral-galaxy rotation curves, and the expansion of the universe, all without dark matter and dark energy. The dynamics for this 3-space follows from a unique generalisation of Newtonian gravity, once that is cast into a velocity formalism. This new theory of gravity is applied to the solar model of the sun to compute new density, pressure and temperature profiles, using polytrope modelling of the equation of state for the matter. These results should be applied to a re-analysis of solar neutrino production, and to stellar evolution in general.
Dynamical 3-Space Gravity Theory: Effects on Polytropic Solar Models
Directory of Open Access Journals (Sweden)
May R. D.
2011-01-01
Full Text Available Numerous experiments and observations have confirmed the existence of a dynamical 3-space, detectable directly by light-speed anisotropy experiments, and indirectly by means of novel gravitational effects, such as bore hole g anomalies, predictable black hole masses, flat spiral-galaxy rotation curves, and the expansion of the universe, all without dark matter and dark energy. The dynamics for this 3-space follows from a unique generalisation of Newtonian gravity, once that is cast into a velocity formalism. This new theory of gravity is applied to the solar model of the sun to compute new density, pressure and temperature profiles, using polytrope modelling of the equation of state for the matter. These results should be applied to a re-analysis of solar neutrino production, and to stellar evolution in general.
Catching the electron in action in real space inside a Ge-Si core-shell nanowire transistor.
Jaishi, Meghnath; Pati, Ranjit
2017-09-21
Catching the electron in action in real space inside a semiconductor Ge-Si core-shell nanowire field effect transistor (FET), which has been demonstrated (J. Xiang, W. Lu, Y. Hu, Y. Wu, H. Yan and C. M. Lieber, Nature, 2006, 441, 489) to outperform the state-of-the-art metal oxide semiconductor FET, is central to gaining unfathomable access into the origin of its functionality. Here, using a quantum transport approach that does not make any assumptions on electronic structure, charge, and potential profile of the device, we unravel the most probable tunneling pathway for electrons in a Ge-Si core-shell nanowire FET with orbital level spatial resolution, which demonstrates gate bias induced decoupling of electron transport between the core and the shell region. Our calculation yields excellent transistor characteristics as noticed in the experiment. Upon increasing the gate bias beyond a threshold value, we observe a rapid drop in drain current resulting in a gate bias driven negative differential resistance behavior and switching in the sign of trans-conductance. We attribute this anomalous behavior in drain current to the gate bias induced modification of the carrier transport pathway from the Ge core to the Si shell region of the nanowire channel. A new experiment involving a four probe junction is proposed to confirm our prediction on gate bias induced decoupling.
A modeling investigation of vowel-to-vowel movement planning in acoustic and muscle spaces
Zandipour, Majid
The primary objective of this research was to explore the coordinate space in which speech movements are planned. A two dimensional biomechanical model of the vocal tract (tongue, lips, jaw, and pharynx) was constructed based on anatomical and physiological data from a subject. The model transforms neural command signals into the actions of muscles. The tongue was modeled by a 221-node finite element mesh. Each of the eight tongue muscles defined within the mesh was controlled by a virtual muscle model. The other vocal-tract components were modeled as simple 2nd-order systems. The model's geometry was adapted to a speaker, using MRI scans of the speaker's vocal tract. The vocal tract model, combined with an adaptive controller that consisted of a forward model (mapping 12-dimensional motor commands to a 64-dimensional acoustic spectrum) and an inverse model (mapping acoustic trajectories to motor command trajectories), was used to simulate and explore the implications of two planning hypotheses: planning in motor space vs. acoustic space. The acoustic, kinematic, and muscle activation (EMG) patterns of vowel-to-vowel sequences generated by the model were compared to data from the speaker whose acoustic, kinematic and EMG were also recorded. The simulation results showed that: (a) modulations of the motor commands effectively accounted for the effects of speaking rate on EMG, kinematic, and acoustic outputs; (b) the movement and acoustic trajectories were influenced by vocal tract biomechanics; and (c) both planning schemes produced similar articulatory movement, EMG, muscle length, force, and acoustic trajectories, which were also comparable to the subject's data under normal speaking conditions. In addition, the effects of a bite-block on measured EMG, kinematics and formants were simulated by the model. Acoustic planning produced successful simulations but motor planning did not. The simulation results suggest that with somatosensory feedback but no auditory
Bessel functions in mass action modeling of memories and remembrances
Energy Technology Data Exchange (ETDEWEB)
Freeman, Walter J. [Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3206 (United States); Capolupo, Antonio [Dipartimento di Fisica, E.R. Caianiello Universitá di Salerno, and INFN Gruppo collegato di Salerno, Fisciano 84084 (Italy); Kozma, Robert [Department of Mathematics, Memphis University, Memphis, TN 38152 (United States); Olivares del Campo, Andrés [The Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BZ (United Kingdom); Vitiello, Giuseppe, E-mail: vitiello@sa.infn.it [Dipartimento di Fisica, E.R. Caianiello Universitá di Salerno, and INFN Gruppo collegato di Salerno, Fisciano 84084 (Italy)
2015-10-02
Data from experimental observations of a class of neurological processes (Freeman K-sets) present functional distribution reproducing Bessel function behavior. We model such processes with couples of damped/amplified oscillators which provide time dependent representation of Bessel equation. The root loci of poles and zeros conform to solutions of K-sets. Some light is shed on the problem of filling the gap between the cellular level dynamics and the brain functional activity. Breakdown of time-reversal symmetry is related with the cortex thermodynamic features. This provides a possible mechanism to deduce lifetime of recorded memory. - Highlights: • We consider data from observations of impulse responses of cortex to electric shocks. • These data are fitted by Bessel functions which may be represented by couples of damped/amplified oscillators. • We study the data by using couples of damped/amplified oscillators. • We discuss lifetime and other properties of the considered brain processes.
Mathematical analysis techniques for modeling the space network activities
Foster, Lisa M.
1992-01-01
The objective of the present work was to explore and identify mathematical analysis techniques, and in particular, the use of linear programming. This topic was then applied to the Tracking and Data Relay Satellite System (TDRSS) in order to understand the space network better. Finally, a small scale version of the system was modeled, variables were identified, data was gathered, and comparisons were made between actual and theoretical data.
Quantum-dot Semiconductor Optical Amplifiers in State Space Model
Institute of Scientific and Technical Information of China (English)
Hussein Taleb; Kambiz Abedi; Saeed Golmohammadi
2013-01-01
A state space model (SSM) is derived for quantum-dot semiconductor optical amplifiers (QD-SOAs).Rate equations of QD-SOA are formulated in the form of state update equations,where average occupation probabilities along QD-SOA cavity are considered as state variables of the system.Simulations show that SSM calculates QD-SOA's static and dynamic characteristics with high accuracy.
The modeling and solution of course of action generation based on IN-DEA
Wan, Lujun; Li, Wen; Dai, Jiangbin; Huang, Aqian
2017-08-01
The course of action (COA) generation is the course of designing the task planning flow, which is one of the key supporting techniques while the military organization executing aerial operation. Due to the outstanding advantage of influence nets (IN), describing the causal logic between random variable, this proposal will introduce IN into the fast building mechanism of COA model. The COA generation model utilize influence nets is established. The probability propagation method is designed, which is based on influence intensity. An improved differential evolution algorithm (IDEA) is designed to solve the action policy optimized selected model. At last, the simulated result of aerial arrack campaign case show the action policy optimized selected in variety influence constants can improve the capability of cause-effect modeling, and the improved differential evolution algorithm has fine convergent and optimized capability.
Christophersen, Catharina
2013-01-01
Arts encounters in schools are often portrayed as encounters between art/artists and children. However, in such encounters, teachers are most often involved. The study presented discusses teachers' experiences with and space for action within The Cultural Rucksack; a national program for arts and culture in Norwegian schools. Observations and…
Recent improvements in atmospheric environment models for Space Station applications
Anderson, B. Jeffrey; Suggs, Ronnie J.; Smith, Robert E.; Hickey, Michael; Catlett, Karen
1991-01-01
The capability of empirical models of the earth's thermosphere must continually be updated if they are to keep pace with their many applications in the aerospace industry. This paper briefly summarizes the progress of several such efforts in support of the Space Station Program. The efforts consists of the development of data bases, analytical studies of the data, and evaluation and intercomparison of thermosphere models. A geomagnetic storm model of Slowey does not compare as well to the MSIS-86 model as does the Marshall Engineering Thermosphere (MET). LDEF orbit decay data is used to evaluate the performance of the MET and MSIS-86 during a period of high solar activity; equal to or exceeding the highest levels that existed during the time of the original data sets upon which these models are based.
Holographic Space-time Models in $1 + 1$ Dimensions
Banks, T
2015-01-01
We construct Holographic Space-time models that reproduce the dynamics of $1 + 1$ dimensional string theory. The necessity for a dilaton field in the $1 + 1$ effective Lagrangian for classical geometry, the appearance of fermions, and even the form of the universal potential in the canonical $1$ matrix model, follow from general HST considerations. We note that 't Hooft's ansatz for the leading contribution to the black hole S-matrix, accounts for the entire S-matrix in these models in the limit that the string scale coincides with the Planck scale, up to transformations between near horizon and asymptotic coordinates. These $1 + 1$ dimensional models are describable as decoupling limits of the near horizon geometry of higher dimensional extremal black holes or black branes, and this suggests that deformations of the simplest model are equally physical. After proposing a notion of "relevant deformations", we describe deformations, which contain excitations corresponding to linear dilaton black holes, some of ...
A semantic space for modeling children's semantic memory
Denhière, Guy; Bellissens, Cédrick; Jhean, Sandra
2008-01-01
The goal of this paper is to present a model of children's semantic memory, which is based on a corpus reproducing the kinds of texts children are exposed to. After presenting the literature in the development of the semantic memory, a preliminary French corpus of 3.2 million words is described. Similarities in the resulting semantic space are compared to human data on four tests: association norms, vocabulary test, semantic judgments and memory tasks. A second corpus is described, which is composed of subcorpora corresponding to various ages. This stratified corpus is intended as a basis for developmental studies. Finally, two applications of these models of semantic memory are presented: the first one aims at tracing the development of semantic similarities paragraph by paragraph; the second one describes an implementation of a model of text comprehension derived from the Construction-integration model (Kintsch, 1988, 1998) and based on such models of semantic memory.
On-line and Model-based Approaches to the Visual Control of Action
Zhao, Huaiyong; Warren, William H.
2014-01-01
Two general approaches to the visual control of action have emerged in last few decades, known as the on-line and model-based approaches. The key difference between them is whether action is controlled by current visual information or on the basis of an internal world model. In this paper, we evaluate three hypotheses: strong on-line control, strong model-based control, and a hybrid solution that combines on-line control with weak off-line strategies. We review experimental research on the co...
Multivariable parametric cost model for space and ground telescopes
Stahl, H. Philip; Henrichs, Todd
2016-09-01
Parametric cost models can be used by designers and project managers to perform relative cost comparisons between major architectural cost drivers and allow high-level design trades; enable cost-benefit analysis for technology development investment; and, provide a basis for estimating total project cost between related concepts. This paper hypothesizes a single model, based on published models and engineering intuition, for both ground and space telescopes: OTA Cost (X) D (1.75 +/- 0.05) λ (-0.5 +/- 0.25) T-0.25 e (-0.04) Y Specific findings include: space telescopes cost 50X to 100X more ground telescopes; diameter is the most important CER; cost is reduced by approximately 50% every 20 years (presumably because of technology advance and process improvements); and, for space telescopes, cost associated with wavelength performance is balanced by cost associated with operating temperature. Finally, duplication only reduces cost for the manufacture of identical systems (i.e. multiple aperture sparse arrays or interferometers). And, while duplication does reduce the cost of manufacturing the mirrors of segmented primary mirror, this cost savings does not appear to manifest itself in the final primary mirror assembly (presumably because the structure for a segmented mirror is more complicated than for a monolithic mirror).
Directory of Open Access Journals (Sweden)
Marcos Antônio Silvestre Gomes
2015-07-01
Full Text Available This article discusses some aspects of the production of urban space considering the social agents actions. The methodology was based on literature searches, data surveys and interviews in public and private agencies, empirical observations and mapping of the urban area. The methodology was based on literature searches, data surveys and interviews in public and private agencies, empirical observations and mapping of the urban area. The objective is to present an analysis of state and real estate developers actions in the production and uneven valorization of urban space in Campos dos Goytacazes-RJ. The results of work indicate the intensification and complexification of actions of these agents with the advent of the oil economy. In the period 1981-2011 there was an intense valuation of South West-East axis of the city, with a vertiginous process of vertical integration and deployment of a high standard closed allotments, which has
THE MODEL CHARACTERISTICS OF JUMP ACTIONS STRUCTURE OF HIGH PERFORMANCE FEMALE VOLLEYBALL PLAYERS
Directory of Open Access Journals (Sweden)
Stech M.
2012-12-01
Full Text Available The purpose of this study was to develop generalized and individual models of the jump actions of skilled female volleyball players. The main prerequisite for the development of the jump actions models were the results of our earlier studies of factor structure of jump actions of 10 sportswomen of the Polish volleyball team "Gedania" (Premier League in the preparatory and competitive periods of the annual cycle of preparation. The athletes age was 22.0 +- 2.9 years, the sports experience - 8.1 +- 3.1 years, body height - 181.9 +- 8.4 years and body weight - 72.8 +- 10.8 kg. Mathematical and statistical processing of the data (the definition of M ± SD and significant differences between the samples was performed using a standard computer program "STATISTICA 7,0". Based on the analysis of the factor structure of 20 jump actions of skilled women volleyball players determined to within 5 of the most informative indexes and their tentative values recommended for the formation of a generalized model of this structure. Comparison of individual models of jump actions of skilled women volleyball players with their generalized models in different periods of preparation can be used for the rational choice of means and methods for the increasing of the training process efficiency.
Phase transition in matrix model with logarithmic action: Toy-model for gluons in baryons
Krishnaswami, G S
2006-01-01
We study the competing effects of gluon self-coupling and their interactions with quarks in a baryon, using the very simple setting of a hermitian 1-matrix model with action tr A^4 - log det(nu + A^2). The logarithmic term comes from integrating out N quarks. The model is a caricature of 2d QCD coupled to adjoint scalars, which are the transversely polarized gluons in a dimensional reduction. nu is a dimensionless ratio of quark mass to coupling constant. The model interpolates between gluons in the vacuum (nu=infinity), gluons weakly coupled to heavy quarks (large nu) and strongly coupled to light quarks in a baryon (nu to 0). It's solution in the large-N limit exhibits a phase transition from a weakly coupled 1-cut phase to a strongly coupled 2-cut phase as nu is decreased below nu_c = 0.27. Free energy and correlation functions are discontinuous in their third and second derivatives at nu_c. The transition to a two-cut phase forces eigenvalues of A away from zero, making glue-ring correlations grow as nu i...
Education as Sustainability: An Action Research Study of the Burns Model of Sustainability Pedagogy
Burns, Heather
2009-01-01
Postsecondary teaching and learning must be reoriented to equip learners with the knowledge, skills, and values they will need for creating a more sustainable world. This action research study examined the effects of implementing the "Burns model of sustainability pedagogy" in university courses taught by the researcher. This model is comprised of…
tThe mode of toxic action (MOA) has been recognized as a key determinant of chemical toxicity andas an alternative to chemical class-based predictive toxicity modeling. However, the development ofquantitative structure activity relationship (QSAR) and other models has been limite...
Multi-Conditional Latent Variable Model for Joint Facial Action Unit Detection
Eleftheriadis, Stefanos; Rudovic, Ognjen; Pantic, Maja
2015-01-01
We propose a novel multi-conditional latent variable model for simultaneous facial feature fusion and detection of facial action units. In our approach we exploit the structure-discovery capabilities of generative models such as Gaussian processes, and the discriminative power of classifiers such as
Operationalizing the Concept of Value--An Action Research-Based Model
Naslund, Dag; Olsson, Annika; Karlsson, Sture
2006-01-01
Purpose: While the importance of measuring customer satisfaction levels is well established, less research exists on how organizations operationalize such knowledge. The purpose of this paper is to describe an action research (AR) case study resulting in a workshop model to operationalize the concept of value. The model facilitates organizational…
Deferred Action: Theoretical model of process architecture design for emergent business processes
Directory of Open Access Journals (Sweden)
Patel, N.V.
2007-01-01
Full Text Available E-Business modelling and ebusiness systems development assumes fixed company resources, structures, and business processes. Empirical and theoretical evidence suggests that company resources and structures are emergent rather than fixed. Planning business activity in emergent contexts requires flexible ebusiness models based on better management theories and models . This paper builds and proposes a theoretical model of ebusiness systems capable of catering for emergent factors that affect business processes. Drawing on development of theories of the ‘action and design’class the Theory of Deferred Action is invoked as the base theory for the theoretical model. A theoretical model of flexible process architecture is presented by identifying its core components and their relationships, and then illustrated with exemplar flexible process architectures capable of responding to emergent factors. Managerial implications of the model are considered and the model’s generic applicability is discussed.
Economic analysis of open space box model utilization in spacecraft
Mohammad, Atif F.; Straub, Jeremy
2015-05-01
It is a known fact that the amount of data about space that is stored is getting larger on an everyday basis. However, the utilization of Big Data and related tools to perform ETL (Extract, Transform and Load) applications will soon be pervasive in the space sciences. We have entered in a crucial time where using Big Data can be the difference (for terrestrial applications) between organizations underperforming and outperforming their peers. The same is true for NASA and other space agencies, as well as for individual missions and the highly-competitive process of mission data analysis and publication. In most industries, conventional opponents and new candidates alike will influence data-driven approaches to revolutionize and capture the value of Big Data archives. The Open Space Box Model is poised to take the proverbial "giant leap", as it provides autonomic data processing and communications for spacecraft. We can find economic value generated from such use of data processing in our earthly organizations in every sector, such as healthcare, retail. We also can easily find retailers, performing research on Big Data, by utilizing sensors driven embedded data in products within their stores and warehouses to determine how these products are actually used in the real world.
Optimal State-Space Reduction for Pedigree Hidden Markov Models
Kirkpatrick, Bonnie
2012-01-01
To analyze whole-genome genetic data inherited in families, the likelihood is typically obtained from a Hidden Markov Model (HMM) having a state space of 2^n hidden states where n is the number of meioses or edges in the pedigree. There have been several attempts to speed up this calculation by reducing the state-space of the HMM. One of these methods has been automated in a calculation that is more efficient than the naive HMM calculation; however, that method treats a special case and the efficiency gain is available for only those rare pedigrees containing long chains of single-child lineages. The other existing state-space reduction method treats the general case, but the existing algorithm has super-exponential running time. We present three formulations of the state-space reduction problem, two dealing with groups and one with partitions. One of these problems, the maximum isometry group problem was discussed in detail by Browning and Browning. We show that for pedigrees, all three of these problems hav...
Borgohain, Gargi; Paul, Sandip
2016-03-10
Classical molecular dynamics simulation of GB1 peptide (a 16-residue β-hairpin) in different osmotic environments is studied. Urea is used for denaturation of the peptide, and trimethylamine-N-oxide (TMAO) is used to offset the effect of urea. Protein-urea electrostatic interactions are found to play a major role in protein-denaturation. To emphasize on protein protecting action of TMAO against urea, two different models of TMAO are used, viz., the Kast model and the Osmotic model. We observe that the Osmotic model of TMAO gives the best protection to counteract urea's action when used in ratio 1:2 of urea:TMAO (i.e., reverse ratio). This is because the presence of TMAO makes urea-protein electrostatic interactions more unfavorable. Preferential solvation of TMAO molecules by urea (and water) molecules is also observed, which causes depletion in the number of urea molecules in the vicinity of the protein. The calculations of intraprotein hydrogen bonds between different residues of protein further reveal the breaking of backbone hydrogen bonds of residues 2 and 15 in the presence of urea, and the same is preserved in the presence of TMAO. Free energy landscapes show that the narrowest distribution is obtained for the osmotic TMAO model when used in reverse ratio.
Liénard-type models for the simulation of the action potential of cardiac nodal cells
Podziemski, P.; Żebrowski, J. J.
2013-10-01
Existing models of cardiac cells which include multi-variable cardiac transmembrane current are too complex to simulate the long time dynamical properties of the heart rhythm. The large number of parameters that need to be defined and set for such models make them not only cumbersome to use but also require a large computing power. Consequently, the application of such models for the bedside analysis of heart rate of a specific patient may be difficult. Other ways of modelling need to be investigated. We consider the general problem of developing a model of cardiac pacemaker tissue that allows to combine the investigation of phenomena at a time scale of thousands of heart beats with the ability to reproduce realistic tissue-level characteristics of cell dynamics. We propose a modified van der Pol-Duffing equation-a Liénard-type oscillator-as a phenomenological model for cardiac nodal tissue, with certain important physiological similarities to ion-channel models of cardiac pacemaker cells. The model presented here is specifically designed to qualitatively reproduce mesoscopic characteristics of cell dynamics, including action potential duration (APD) restitution properties, phase response characteristics, and phase space structure. We show that these characteristics agree qualitatively with the extensive ionic models and experimental results in the literature [Anumonwo et al., 1991, [33], Cao et al., 1999, [49], Coster and Celler, 2003, [31], Qu, 2004, [45], Tsalikakis et al., 2007, [32], Inada et al., 2009, [14], Qu et al., 2010, [50
A logistics model for large space power systems
Koelle, H. H.
Space Power Systems (SPS) have to overcome two hurdles: (1) to find an attractive design, manufacturing and assembly concept and (2) to have available a space transportation system that can provide economical logistic support during the construction and operational phases. An initial system feasibility study, some five years ago, was based on a reference system that used terrestrial resources only and was based partially on electric propulsion systems. The conclusion was: it is feasible but not yet economically competitive with other options. This study is based on terrestrial and extraterrestrial resources and on chemical (LH 2/LOX) propulsion systems. These engines are available from the Space Shuttle production line and require small changes only. Other so-called advanced propulsion systems investigated did not prove economically superior if lunar LOX is available! We assume that a Shuttle derived Heavy Lift Launch Vehicle (HLLV) will become available around the turn of the century and that this will be used to establish a research base on the lunar surface. This lunar base has the potential to grow into a lunar factory producing LOX and construction materials for supporting among other projects also the construction of space power systems in geostationary orbit. A model was developed to simulate the logistics support of such an operation for a 50-year life cycle. After 50 years 111 SPS units with 5 GW each and an availability of 90% will produce 100 × 5 = 500 GW. The model comprises 60 equations and requires 29 assumptions of the parameter involved. 60-state variables calculated with the 60 equations mentioned above are given on an annual basis and as averages for the 50-year life cycle. Recycling of defective parts in geostationary orbit is one of the features of the model. The state-of-the-art with respect to SPS technology is introduced as a variable Mg mass/MW electric power delivered. If the space manufacturing facility, a maintenance and repair facility
Directory of Open Access Journals (Sweden)
Daniel Weiller
2010-05-01
Full Text Available Here we introduce a cognitive model capable to model a variety of behavioral domains and apply it to a navigational task. We used place cells as sensory representation, such that the cells’ place fields divided the environment into discrete states. The robot learns knowledge of the environment by memorizing the sensory outcome of its motor actions. This is composed of a central process, learning the probability of state-to-state transitions by motor actions and a distal processing routine, learning the extent to which these state-to-state transitions are caused by sensory-driven reflex behavior (obstacle avoidance. Navigational decision making integrates central and distal learned environmental knowledge to select an action that leads to a goal state. Differentiating distal and central processing increases the behavioral accuracy of the selected actions and the ability of behavioral adaptation to a changed environment. We propose that the system can canonically be expanded to model other behaviors, using alternative definitions of states and actions. The emphasis of this paper is to test this general cognitive model on a robot in a real world environment
A Neural Dynamic Model Generates Descriptions of Object-Oriented Actions.
Richter, Mathis; Lins, Jonas; Schöner, Gregor
2017-01-01
Describing actions entails that relations between objects are discovered. A pervasively neural account of this process requires that fundamental problems are solved: the neural pointer problem, the binding problem, and the problem of generating discrete processing steps from time-continuous neural processes. We present a prototypical solution to these problems in a neural dynamic model that comprises dynamic neural fields holding representations close to sensorimotor surfaces as well as dynamic neural nodes holding discrete, language-like representations. Making the connection between these two types of representations enables the model to describe actions as well as to perceptually ground movement phrases-all based on real visual input. We demonstrate how the dynamic neural processes autonomously generate the processing steps required to describe or ground object-oriented actions. By solving the fundamental problems of neural pointing, binding, and emergent discrete processing, the model may be a first but critical step toward a systematic neural processing account of higher cognition.
Rapid State Space Modeling Tool for Rectangular Wing Aeroservoelastic Studies
Suh, Peter M.; Conyers, Howard Jason; Mavris, Dimitri N.
2015-01-01
This report introduces a modeling and simulation tool for aeroservoelastic analysis of rectangular wings with trailing-edge control surfaces. The inputs to the code are planform design parameters such as wing span, aspect ratio, and number of control surfaces. Using this information, the generalized forces are computed using the doublet-lattice method. Using Roger's approximation, a rational function approximation is computed. The output, computed in a few seconds, is a state space aeroservoelastic model which can be used for analysis and control design. The tool is fully parameterized with default information so there is little required interaction with the model developer. All parameters can be easily modified if desired. The focus of this report is on tool presentation, verification, and validation. These processes are carried out in stages throughout the report. The rational function approximation is verified against computed generalized forces for a plate model. A model composed of finite element plates is compared to a modal analysis from commercial software and an independently conducted experimental ground vibration test analysis. Aeroservoelastic analysis is the ultimate goal of this tool, therefore, the flutter speed and frequency for a clamped plate are computed using damping-versus-velocity and frequency-versus-velocity analysis. The computational results are compared to a previously published computational analysis and wind-tunnel results for the same structure. A case study of a generic wing model with a single control surface is presented. Verification of the state space model is presented in comparison to damping-versus-velocity and frequency-versus-velocity analysis, including the analysis of the model in response to a 1-cos gust.
2006-08-01
Social Network Modeling, Organizational Modeling, Effects-Based Operations, Knowledge Creation Modeling, Learning Organization 16. SECURITY...SYSTEM SJ SYSTEM INTERACTIONS AND INFLUENCES SOCIAL ORGANIZATIONAL SYSTEM SYSTEM I Multiple actors egaglng In comunities of Commrunitles of Interest...actors’ understanding of the JTF problem space. " The process of staff learning is not addressed in the present simulation mode. Here, staff learning is
Space Partitioning for Privacy Enabled 3D City Models
Filippovska, Y.; Wichmann, A.; Kada, M.
2016-10-01
Due to recent technological progress, data capturing and processing of highly detailed (3D) data has become extensive. And despite all prospects of potential uses, data that includes personal living spaces and public buildings can also be considered as a serious intrusion into people's privacy and a threat to security. It becomes especially critical if data is visible by the general public. Thus, a compromise is needed between open access to data and privacy requirements which can be very different for each application. As privacy is a complex and versatile topic, the focus of this work particularly lies on the visualization of 3D urban data sets. For the purpose of privacy enabled visualizations of 3D city models, we propose to partition the (living) spaces into privacy regions, each featuring its own level of anonymity. Within each region, the depicted 2D and 3D geometry and imagery is anonymized with cartographic generalization techniques. The underlying spatial partitioning is realized as a 2D map generated as a straight skeleton of the open space between buildings. The resulting privacy cells are then merged according to the privacy requirements associated with each building to form larger regions, their borderlines smoothed, and transition zones established between privacy regions to have a harmonious visual appearance. It is exemplarily demonstrated how the proposed method generates privacy enabled 3D city models.
On vector autoregressive modeling in space and time
di Giacinto, Valter
2010-06-01
Despite the fact that it provides a potentially useful analytical tool, allowing for the joint modeling of dynamic interdependencies within a group of connected areas, until lately the VAR approach had received little attention in regional science and spatial economic analysis. This paper aims to contribute in this field by dealing with the issues of parameter identification and estimation and of structural impulse response analysis. In particular, there is a discussion of the adaptation of the recursive identification scheme (which represents one of the more common approaches in the time series VAR literature) to a space-time environment. Parameter estimation is subsequently based on the Full Information Maximum Likelihood (FIML) method, a standard approach in structural VAR analysis. As a convenient tool to summarize the information conveyed by regional dynamic multipliers with a specific emphasis on the scope of spatial spillover effects, a synthetic space-time impulse response function (STIR) is introduced, portraying average effects as a function of displacement in time and space. Asymptotic confidence bands for the STIR estimates are also derived from bootstrap estimates of the standard errors. Finally, to provide a basic illustration of the methodology, the paper presents an application of a simple bivariate fiscal model fitted to data for Italian NUTS 2 regions.
a New Einstein-Hilbert Action and a Superon-Graviton Model (sgm) of Nature
Shima, Kazunari; Tsuda, Motomu; Sawaguchi, Manabu
A nonlinear supersymmetric (NLSUSY) Einstein-Hilbert (EH)-type new action for the unity of nature is obtained by performing Einstein gravity analogue geometrical arguments in high symmetry spacetime inspired by NLSUSY. The new action is unstable and breaks down spontaneously into the EH action with matter in ordinary Riemann spacetime. All elementary particles except the graviton are composed of the fundamental fermion "superon" (the Nambu-Goldstone (NG) fermion of NLSUSY) and regarded as the eigenstates of SO(10) super-Poincaré (SP) algebra, called the superon-graviton model (SGM) of nature. Some phenomenological implications for low energy particle physics and cosmology are discussed. The linearization of NLSUSY including N=1 SGM action is attempted explicitly to obtain the linear SUSY local field theory, which is equivalent and renormalizable.
A Bayesian state-space formulation of dynamic occupancy models.
Royle, J Andrew; Kéry, Marc
2007-07-01
Species occurrence and its dynamic components, extinction and colonization probabilities, are focal quantities in biogeography and metapopulation biology, and for species conservation assessments. It has been increasingly appreciated that these parameters must be estimated separately from detection probability to avoid the biases induced by non-detection error. Hence, there is now considerable theoretical and practical interest in dynamic occupancy models that contain explicit representations of metapopulation dynamics such as extinction, colonization, and turnover as well as growth rates. We describe a hierarchical parameterization of these models that is analogous to the state-space formulation of models in time series, where the model is represented by two components, one for the partially observable occupancy process and another for the observations conditional on that process. This parameterization naturally allows estimation of all parameters of the conventional approach to occupancy models, but in addition, yields great flexibility and extensibility, e.g., to modeling heterogeneity or latent structure in model parameters. We also highlight the important distinction between population and finite sample inference; the latter yields much more precise estimates for the particular sample at hand. Finite sample estimates can easily be obtained using the state-space representation of the model but are difficult to obtain under the conventional approach of likelihood-based estimation. We use R and WinBUGS to apply the model to two examples. In a standard analysis for the European Crossbill in a large Swiss monitoring program, we fit a model with year-specific parameters. Estimates of the dynamic parameters varied greatly among years, highlighting the irruptive population dynamics of that species. In the second example, we analyze route occupancy of Cerulean Warblers in the North American Breeding Bird Survey (BBS) using a model allowing for site
A Bayesian state-space formulation of dynamic occupancy models
Royle, J. Andrew; Kery, M.
2007-01-01
Species occurrence and its dynamic components, extinction and colonization probabilities, are focal quantities in biogeography and metapopulation biology, and for species conservation assessments. It has been increasingly appreciated that these parameters must be estimated separately from detection probability to avoid the biases induced by nondetection error. Hence, there is now considerable theoretical and practical interest in dynamic occupancy models that contain explicit representations of metapopulation dynamics such as extinction, colonization, and turnover as well as growth rates. We describe a hierarchical parameterization of these models that is analogous to the state-space formulation of models in time series, where the model is represented by two components, one for the partially observable occupancy process and another for the observations conditional on that process. This parameterization naturally allows estimation of all parameters of the conventional approach to occupancy models, but in addition, yields great flexibility and extensibility, e.g., to modeling heterogeneity or latent structure in model parameters. We also highlight the important distinction between population and finite sample inference; the latter yields much more precise estimates for the particular sample at hand. Finite sample estimates can easily be obtained using the state-space representation of the model but are difficult to obtain under the conventional approach of likelihood-based estimation. We use R and Win BUGS to apply the model to two examples. In a standard analysis for the European Crossbill in a large Swiss monitoring program, we fit a model with year-specific parameters. Estimates of the dynamic parameters varied greatly among years, highlighting the irruptive population dynamics of that species. In the second example, we analyze route occupancy of Cerulean Warblers in the North American Breeding Bird Survey (BBS) using a model allowing for site
LATEST: A model of saccadic decisions in space and time.
Tatler, Benjamin W; Brockmole, James R; Carpenter, R H S
2017-04-01
Many of our actions require visual information, and for this it is important to direct the eyes to the right place at the right time. Two or three times every second, we must decide both when and where to direct our gaze. Understanding these decisions can reveal the moment-to-moment information priorities of the visual system and the strategies for information sampling employed by the brain to serve ongoing behavior. Most theoretical frameworks and models of gaze control assume that the spatial and temporal aspects of fixation point selection depend on different mechanisms. We present a single model that can simultaneously account for both when and where we look. Underpinning this model is the theoretical assertion that each decision to move the eyes is an evaluation of the relative benefit expected from moving the eyes to a new location compared with that expected by continuing to fixate the current target. The eyes move when the evidence that favors moving to a new location outweighs that favoring staying at the present location. Our model provides not only an account of when the eyes move, but also what will be fixated. That is, an analysis of saccade timing alone enables us to predict where people look in a scene. Indeed our model accounts for fixation selection as well as (and often better than) current computational models of fixation selection in scene viewing. (PsycINFO Database Record
Validation of elastic cross section models for space radiation applications
Werneth, C. M.; Xu, X.; Norman, R. B.; Ford, W. P.; Maung, K. M.
2017-02-01
The space radiation field is composed of energetic particles that pose both acute and long-term risks for astronauts in low earth orbit and beyond. In order to estimate radiation risk to crew members, the fluence of particles and biological response to the radiation must be known at tissue sites. Given that the spectral fluence at the boundary of the shielding material is characterized, radiation transport algorithms may be used to find the fluence of particles inside the shield and body, and the radio-biological response is estimated from experiments and models. The fidelity of the radiation spectrum inside the shield and body depends on radiation transport algorithms and the accuracy of the nuclear cross sections. In a recent study, self-consistent nuclear models based on multiple scattering theory that include the option to study relativistic kinematics were developed for the prediction of nuclear cross sections for space radiation applications. The aim of the current work is to use uncertainty quantification to ascertain the validity of the models as compared to a nuclear reaction database and to identify components of the models that can be improved in future efforts.
Theories and models on the biological of cells in space
Todd, P.; Klaus, D. M.
1996-01-01
A wide variety of observations on cells in space, admittedly made under constraining and unnatural conditions in may cases, have led to experimental results that were surprising or unexpected. Reproducibility, freedom from artifacts, and plausibility must be considered in all cases, even when results are not surprising. The papers in symposium on 'Theories and Models on the Biology of Cells in Space' are dedicated to the subject of the plausibility of cellular responses to gravity -- inertial accelerations between 0 and 9.8 m/sq s and higher. The mechanical phenomena inside the cell, the gravitactic locomotion of single eukaryotic and prokaryotic cells, and the effects of inertial unloading on cellular physiology are addressed in theoretical and experimental studies.
Theories and models on the Biology of Cells in Space
Todd, P.; Klaus, D. M.
A wide variety of observations on cells in space, admittedly made under constraining and unnatural conditions in many cases, have led to experimental results that were surprising or unexpected. Reproducibility, freedom from artifacts, and plausibility must be considered in all cases, even when results are not surprising. The papers in the symposium on ``Theories and Models on the Biology of Cells in Space'' are dedicated to the subject of theplausibility of cellular responses to gravity -- inertial accelerations between 0 and 9.8 m/s^2 and higher. The mechanical phenomena inside the cell, the gravitactic locomotion of single eukaryotic and prokaryotic cells, and the effects of inertial unloading on cellular physiology are addressed in theoretical and experimental studies.
Gilet, Estelle; Diard, Julien; Bessière, Pierre
2011-01-01
In this paper, we study the collaboration of perception and action representations involved in cursive letter recognition and production. We propose a mathematical formulation for the whole perception-action loop, based on probabilistic modeling and bayesian inference, which we call the Bayesian Action-Perception (BAP) model. Being a model of both perception and action processes, the purpose of this model is to study the interaction of these processes. More precisely, the model includes a feedback loop from motor production, which implements an internal simulation of movement. Motor knowledge can therefore be involved during perception tasks. In this paper, we formally define the BAP model and show how it solves the following six varied cognitive tasks using bayesian inference: i) letter recognition (purely sensory), ii) writer recognition, iii) letter production (with different effectors), iv) copying of trajectories, v) copying of letters, and vi) letter recognition (with internal simulation of movements). We present computer simulations of each of these cognitive tasks, and discuss experimental predictions and theoretical developments.
Directory of Open Access Journals (Sweden)
Estelle Gilet
Full Text Available In this paper, we study the collaboration of perception and action representations involved in cursive letter recognition and production. We propose a mathematical formulation for the whole perception-action loop, based on probabilistic modeling and bayesian inference, which we call the Bayesian Action-Perception (BAP model. Being a model of both perception and action processes, the purpose of this model is to study the interaction of these processes. More precisely, the model includes a feedback loop from motor production, which implements an internal simulation of movement. Motor knowledge can therefore be involved during perception tasks. In this paper, we formally define the BAP model and show how it solves the following six varied cognitive tasks using bayesian inference: i letter recognition (purely sensory, ii writer recognition, iii letter production (with different effectors, iv copying of trajectories, v copying of letters, and vi letter recognition (with internal simulation of movements. We present computer simulations of each of these cognitive tasks, and discuss experimental predictions and theoretical developments.
Documentation of a Model Action Plan to Deter Illicit Nuclear Trafficking
Energy Technology Data Exchange (ETDEWEB)
Smith, D; Kristo, M; Niemeyer, S; Dudder, G
2006-07-28
Theft, illegal possession, smuggling, or attempted unauthorized sale of nuclear and radiological materials remains a worldwide problem. The Nuclear Smuggling International Technical Working Group (ITWG) has adopted a model action plan to guide investigation of these cases through a systematic approach to nuclear forensics. The model action plan was recently documented and provides recommendations concerning incident response, collection of evidence in conformance with required legal standards, laboratory sampling and distribution of samples, radioactive materials analysis, including categorization and characterization of samples, forensics analysis of conventional evidence, and case development including interpretation of forensic signatures.
Molecular Dynamics Modeling of Tethered Organics in Confined Spaces
Energy Technology Data Exchange (ETDEWEB)
Waksburg, Avi [Monash University, Australia; Nguyen, M [Monash University, Australia; Chaffe, Alan [Monash University, Australia; Kidder, Michelle [ORNL; Buchanan III, A C [ORNL; Britt, Phillip F [ORNL
2011-01-01
A computational method for constructing and evaluating the dynamic behaviour of functionalised hexagonal mesoporous silica (HMS) MCM-41 models is reported. HMS with three pore diameters (1.7, 2.2 and 2.9 nm) were prepared, and, from these, two series of derivative structures were constructed - one with 1,3-diphenylpropyl (DPP) tethers and the other with smaller dimethylsilyl (DMS) tethers attached to the mesopores internal surfaces. Comparison with experimental data shows that simulation results correctly predict the maximum tether density that can be achieved for each tether and each pore diameter. For the smaller pore models, the extent of DPP functionalisation that can be achieved is limited by the available pore volume. However, for the larger pore model, the extent of functionalisation is limited by access to potentially reactive sites on the pore surface. The dynamic behaviour of the models was investigated over a range of temperatures (240-648 K). At lower temperatures (< 400 K), the mobility of DPP tethers in the 2.9 nm model is actually less than that observed in either the 2.2 nm model or the 1.7 nm model due to the extensive non-bonded interactions that are able to develop between tethers and the silica surface at this diameter. At higher temperatures, the free ends of these tethers break away from the surface, extend further into the pore space and the DPP mobility in the 2.9 nm model is higher than in the smaller pore systems.
Nonlinear State Space Modeling and System Identification for Electrohydraulic Control
Directory of Open Access Journals (Sweden)
Jun Yan
2013-01-01
Full Text Available The paper deals with nonlinear modeling and identification of an electrohydraulic control system for improving its tracking performance. We build the nonlinear state space model for analyzing the highly nonlinear system and then develop a Hammerstein-Wiener (H-W model which consists of a static input nonlinear block with two-segment polynomial nonlinearities, a linear time-invariant dynamic block, and a static output nonlinear block with single polynomial nonlinearity to describe it. We simplify the H-W model into a linear-in-parameters structure by using the key term separation principle and then use a modified recursive least square method with iterative estimation of internal variables to identify all the unknown parameters simultaneously. It is found that the proposed H-W model approximates the actual system better than the independent Hammerstein, Wiener, and ARX models. The prediction error of the H-W model is about 13%, 54%, and 58% less than the Hammerstein, Wiener, and ARX models, respectively.
Action Recognition using Motion Primitives
DEFF Research Database (Denmark)
Moeslund, Thomas B.; Fihl, Preben; Holte, Michael Boelstoft
The number of potential applications has made automatic recognition of human actions a very active research area. Different approaches have been followed based on trajectories through some state space. In this paper we also model an action as a trajectory through a state space, but we represent...... the actions as a sequence of temporal isolated instances, denoted primitives. These primitives are each defined by four features extracted from motion images. The primitives are recognized in each frame based on a trained classifier resulting in a sequence of primitives. From this sequence we recognize...
Haveman, Steven; Bonnema, Gerrit Maarten
2013-01-01
Most formal models are used in detailed design and focus on a single domain. Few effective approaches exist that can effectively tie these lower level models to a high level system model during design space exploration. This complicates the validation of high level system requirements during
Directory of Open Access Journals (Sweden)
Stephane eGrade
2015-06-01
Full Text Available The perception of reachability (i.e., whether an object is within reach relies on body representations and action simulation. Similarly, egocentric distance estimation (i.e., the perception of the distance an object is from the self is thought to be partly derived from embodied action simulation. Although motor simulation is important for both, it is unclear whether the cognitive processes underlying these behaviors rely on the same motor processes. To investigate this, we measured the impact of a motor interference dual-task paradigm on reachability judgment, egocentric distance estimation, and allocentric length estimation (i.e., how distant two stimuli are from each other independent from the self used as a control task. Participants were required to make concurrent actions with either hand actions of foam ball grip squeezing or arm actions of weight lifting, or no concurrent actions. Results showed that concurrent squeeze actions significantly slowed response speed in the reachability judgment and egocentric distance estimation tasks, but that there was no impact of the concurrent actions on allocentric length estimation. Together, these results suggest that reachability and distance perception, both egocentric perspective tasks, and in contrast to the allocentric perspective task, involve action simulation cognitive processes. The results are discussed in terms of the implication of action simulation when evaluating the position of a target relative to the observer’s body, supporting an embodied view of spatial cognition.
Chen, Chang-Kun; Li, Zhi; Sun, Yun-Feng
A new model for describing the disaster system including instantaneous and continuous action synchronously has been developed. The model is composed of three primary parts, that is, the impact from its causative disaster events, stochastic noise of disaster node and self-healing function, and every part is modeled concretely in terms of their characteristics in practice. Some key parameters, namely link appearance probability, retardation coefficient, ultimate repair capacity of government, dynamical modes considering different disaster evolving chains, and the positions of link with the specific performance in disaster network system are involved. Combined with a case study, the proposed model is applied to a certain disaster evolution system, and the influence law of different parameters on disaster evolution process, in disaster networks with instantaneous-action and/or continuous-action, is presented and compared. The results indicate that the destructive impact in the networks by link in continuous action is far greater an order of magnitude than that in instantaneous action. If a link in continuous action emerges in the disaster network system, properties of the causative event for the link, link appearance probability and its position in the network all have a notable influence to the severity of the disaster network. In addition, some peculiar phenomena are also commendably observed in the disaster evolution process based on the model, such as the multipeaks emerging in the destroyed rate number curve for some crisis nodes caused by their various inducing paths together with the relevant retardation coefficients, the existence of the critical value for ultimate repair capacity to recover the disaster node, and so on.
Institute of Scientific and Technical Information of China (English)
张毅
2013-01-01
The Noether symmetry and the conserved quantity for a fractional action-like variational problem in phase space are studied based on the method of fractional dynamics modeling presented by ElNabulsi,namely fractional action-like variational approach.First,the fractional action-like variational problem in phase space is established,and the fractional action-like Hamilton canonical equations are obtained.Secondly,the definitions and criteria of the fractional action-like Noether (quasi-) symmetrical transformations are presented in terms of the invariance of the fractional action-like integral of Hamilton under the infinitesimal transformation of group.Finally,the Noether theorems for the fractional actionlike Hamiltonian system are given,the relationship between the Noether symmetry and the conserved quantity of the system is established.An example is given to illustrate the application of the results.%基于El-Nabulsi提出的分数阶动力学建模方法,即类分数阶变分方法,研究相空间中类分数阶变分问题与Noether对称性和守恒量.建立了相空间中类分数阶变分问题,得到了类分数阶Hamilton正则方程；基于类分数阶Hamilton作用量在无限小群变换下的不变性,提出了相空间中类分数阶Noether(准)对称变换的定义和判据；给出了类分数阶Hamilton系统的Noether定理,建立了类分数阶Noether对称性与守恒量之间的内在关系,并举例说明结果的应用.
Space shuttle’s liftoff: a didactical model
Borghi, Riccardo; Spinozzi, Turi Maria
2017-07-01
The pedagogical aim of the present paper, thought for an undergraduate audience, is to help students to appreciate how the development of elementary models based on physics first principles is a fundamental and necessary preliminary step for the behaviour of complex real systems to be grasped with minimal amounts of math. In some particularly fortunate cases, such models also show reasonably good results when are compared to reality. The speed behaviour of the Space Shuttle during its first two minutes of flight from liftoff is here analysed from such a didactical point of view. Only the momentum conservation law is employed to develop the model, which is eventually applied to quantitatively interpret the telemetry of the 2011 last launches of Shuttle Discovery and Shuttle Endeavour. To the STS-51-L and STS-107 astronauts, in memoriam.
Real space renormalization group theory of disordered models of glasses.
Angelini, Maria Chiara; Biroli, Giulio
2017-03-28
We develop a real space renormalization group analysis of disordered models of glasses, in particular of the spin models at the origin of the random first-order transition theory. We find three fixed points, respectively, associated with the liquid state, with the critical behavior, and with the glass state. The latter two are zero-temperature ones; this provides a natural explanation of the growth of effective activation energy scale and the concomitant huge increase of relaxation time approaching the glass transition. The lower critical dimension depends on the nature of the interacting degrees of freedom and is higher than three for all models. This does not prevent 3D systems from being glassy. Indeed, we find that their renormalization group flow is affected by the fixed points existing in higher dimension and in consequence is nontrivial. Within our theoretical framework, the glass transition results in an avoided phase transition.
[Prognostic model of the space station contamination stage].
Zlotovol'skiĭ, V M; Smolenskaia, G S
1998-01-01
Forty two non-metallic materials, 8 human metabolites and a process liquid (ethylene glycol) were selected for development of a prognostic model of space station contamination by harmful trace admixtures (HTAs). Removal technologies made allowance for absorption by atmospheric condensate (AC) and filter adsorption. Calculations took in 18 HTAs representative of 8 classes of compounds. Simulation modeling allowed to determine HTA migration rates and percent ratio (1), calculate concentrations of contaminants in the atmosphere and atmospheric condensate (2), and to assess filter efficiency by comparison of loads on the filter and a refrigeration/drying set (3). Comparison of empirical and measured data permitted conclusions about adequacy of the model and its potentiality for predicting ramifications of nominal and contingency situations.
Operational Space Weather Models: Trials, Tribulations and Rewards
Schunk, R. W.; Scherliess, L.; Sojka, J. J.; Thompson, D. C.; Zhu, L.
2009-12-01
There are many empirical, physics-based, and data assimilation models that can probably be used for space weather applications and the models cover the entire domain from the surface of the Sun to the Earth’s surface. At Utah State University we developed two physics-based data assimilation models of the terrestrial ionosphere as part of a program called Global Assimilation of Ionospheric Measurements (GAIM). One of the data assimilation models is now in operational use at the Air Force Weather Agency (AFWA) in Omaha, Nebraska. This model is a Gauss-Markov Kalman Filter (GAIM-GM) model, and it uses a physics-based model of the ionosphere and a Kalman filter as a basis for assimilating a diverse set of real-time (or near real-time) measurements. The physics-based model is the Ionosphere Forecast Model (IFM), which is global and covers the E-region, F-region, and topside ionosphere from 90 to 1400 km. It takes account of five ion species (NO+, O2+, N2+, O+, H+), but the main output of the model is a 3-dimensional electron density distribution at user specified times. The second data assimilation model uses a physics-based Ionosphere-Plasmasphere Model (IPM) and an ensemble Kalman filter technique as a basis for assimilating a diverse set of real-time (or near real-time) measurements. This Full Physics model (GAIM-FP) is global, covers the altitude range from 90 to 30,000 km, includes six ions (NO+, O2+, N2+, O+, H+, He+), and calculates the self-consistent ionospheric drivers (electric fields and neutral winds). The GAIM-FP model is scheduled for delivery in 2012. Both of these GAIM models assimilate bottom-side Ne profiles from a variable number of ionosondes, slant TEC from a variable number of ground GPS/TEC stations, in situ Ne from four DMSP satellites, line-of-sight UV emissions measured by satellites, and occultation data. Quality control algorithms for all of the data types are provided as an integral part of the GAIM models and these models take account of
A Knowledge Discovery from POS Data using State Space Models
Sato, Tadahiko; Higuchi, Tomoyuki
The number of competing-brands changes by new product's entry. The new product introduction is endemic among consumer packaged goods firm and is an integral component of their marketing strategy. As a new product's entry affects markets, there is a pressing need to develop market response model that can adapt to such changes. In this paper, we develop a dynamic model that capture the underlying evolution of the buying behavior associated with the new product. This extends an application of a dynamic linear model, which is used by a number of time series analyses, by allowing the observed dimension to change at some point in time. Our model copes with a problem that dynamic environments entail: changes in parameter over time and changes in the observed dimension. We formulate the model with framework of a state space model. We realize an estimation of the model using modified Kalman filter/fixed interval smoother. We find that new product's entry (1) decreases brand differentiation for existing brands, as indicated by decreasing difference between cross-price elasticities; (2) decreases commodity power for existing brands, as indicated by decreasing trend; and (3) decreases the effect of discount for existing brands, as indicated by a decrease in the magnitude of own-brand price elasticities. The proposed framework is directly applicable to other fields in which the observed dimension might be change, such as economic, bioinformatics, and so forth.
Reliability models applicable to space telescope solar array assembly system
Patil, S. A.
1986-01-01
A complex system may consist of a number of subsystems with several components in series, parallel, or combination of both series and parallel. In order to predict how well the system will perform, it is necessary to know the reliabilities of the subsystems and the reliability of the whole system. The objective of the present study is to develop mathematical models of the reliability which are applicable to complex systems. The models are determined by assuming k failures out of n components in a subsystem. By taking k = 1 and k = n, these models reduce to parallel and series models; hence, the models can be specialized to parallel, series combination systems. The models are developed by assuming the failure rates of the components as functions of time and as such, can be applied to processes with or without aging effects. The reliability models are further specialized to Space Telescope Solar Arrray (STSA) System. The STSA consists of 20 identical solar panel assemblies (SPA's). The reliabilities of the SPA's are determined by the reliabilities of solar cell strings, interconnects, and diodes. The estimates of the reliability of the system for one to five years are calculated by using the reliability estimates of solar cells and interconnects given n ESA documents. Aging effects in relation to breaks in interconnects are discussed.
Directory of Open Access Journals (Sweden)
Gabriel A. Radvansky
2016-01-01
Full Text Available The Fluid Events Model is aimed at predicting changes in the actions people take on a moment-by-moment basis. In contrast with other research on action selection, this work does not investigate why some course of action was selected, but rather the likelihood of discontinuing the current course of action and selecting another in the near future. This is done using both task-based and experience-based factors. Prior work evaluated this model in the context of trial-by-trial, independent, interactive events, such as choosing how to copy a figure of a line drawing. In this paper, we extend this model to more covert event experiences, such as reading narratives, as well as to continuous interactive events, such as playing a video game. To this end, the model was applied to existing data sets of reading time and event segmentation for written and picture stories. It was also applied to existing data sets of performance in a strategy board game, an aerial combat game, and a first person shooter game in which a participant’s current state was dependent on prior events. The results revealed that the model predicted behavior changes well, taking into account both the theoretically defined structure of the described events, as well as a person’s prior experience. Thus, theories of event cognition can benefit from efforts that take into account not only how events in the world are structured, but also how people experience those events.
Radvansky, Gabriel A; D'Mello, Sidney K; Abbott, Robert G; Bixler, Robert E
2016-01-01
The Fluid Events Model is aimed at predicting changes in the actions people take on a moment-by-moment basis. In contrast with other research on action selection, this work does not investigate why some course of action was selected, but rather the likelihood of discontinuing the current course of action and selecting another in the near future. This is done using both task-based and experience-based factors. Prior work evaluated this model in the context of trial-by-trial, independent, interactive events, such as choosing how to copy a figure of a line drawing. In this paper, we extend this model to more covert event experiences, such as reading narratives, as well as to continuous interactive events, such as playing a video game. To this end, the model was applied to existing data sets of reading time and event segmentation for written and picture stories. It was also applied to existing data sets of performance in a strategy board game, an aerial combat game, and a first person shooter game in which a participant's current state was dependent on prior events. The results revealed that the model predicted behavior changes well, taking into account both the theoretically defined structure of the described events, as well as a person's prior experience. Thus, theories of event cognition can benefit from efforts that take into account not only how events in the world are structured, but also how people experience those events.
Health Belief Model and Reasoned Action Theory in Predicting Water Saving Behaviors in Yazd, Iran
Directory of Open Access Journals (Sweden)
Mohammad Taghi Ghaneian
2012-12-01
Full Text Available Background: People's behaviors and intentions about healthy behaviors depend on their beliefs, values, and knowledge about the issue. Various models of health education are used in deter-mining predictors of different healthy behaviors but their efficacy in cultural behaviors, such as water saving behaviors, are not studied. The study was conducted to explain water saving beha-viors in Yazd, Iran on the basis of Health Belief Model and Reasoned Action Theory. Methods: The cross-sectional study used random cluster sampling to recruit 200 heads of households to collect the data. The survey questionnaire was tested for its content validity and reliability. Analysis of data included descriptive statistics, simple correlation, hierarchical multiple regression. Results: Simple correlations between water saving behaviors and Reasoned Action Theory and Health Belief Model constructs were statistically significant. Health Belief Model and Reasoned Action Theory constructs explained 20.80% and 8.40% of the variances in water saving beha-viors, respectively. Perceived barriers were the strongest Predictor. Additionally, there was a sta-tistically positive correlation between water saving behaviors and intention. Conclusion: In designing interventions aimed at water waste prevention, barriers of water saving behaviors should be addressed first, followed by people's attitude towards water saving. Health Belief Model constructs, with the exception of perceived severity and benefits, is more powerful than is Reasoned Action Theory in predicting water saving behavior and may be used as a framework for educational interventions aimed at improving water saving behaviors.
Cerba Diaconescu, Oxana; Schlomiuk, Dana; Vulpe, Nicolae
In this article, we consider the class QSL4{u +vc+w^c, ∞ } of all real quadratic differential systems (dx)/(dt) = p(x, y), (dy)/(dt) = q(x, y) with gcd(p, q) = 1, having invariant lines of total multiplicity four and two complex and one real infinite singularities. We first construct compactified canonical forms for the class QSL4{u +vc+w^c, ∞ } so as to include limit points in the 12-dimensional parameter space of this class. We next construct the bifurcation diagrams for these compactified canonical forms. These diagrams contain many repetitions of phase portraits and we show that these are due to many symmetries under the group action. To retain the essence of the dynamics we finally construct the quotient spaces under the action of the group G = Aff(2, ℝ) × ℝ* of affine transformations and time homotheties and we place the phase portraits in these quotient spaces. The final diagrams retain only the necessary information to capture the dynamics under the motion in the parameter space as well as under this group action. We also present here necessary and sufficient conditions for an affine line to be invariant of multiplicity k for a quadratic system.
Differential geometry of the space of Ising models
Machta, Benjamin; Chachra, Ricky; Transtrum, Mark; Sethna, James
2012-02-01
We use information geometry to understand the emergence of simple effective theories, using an Ising model perturbed with terms coupling non-nearest-neighbor spins as an example. The Fisher information is a natural metric of distinguishability for a parameterized space of probability distributions, applicable to models in statistical physics. Near critical points both the metric components (four-point susceptibilities) and the scalar curvature diverge with corresponding critical exponents. However, connections to Renormalization Group (RG) ideas have remained elusive. Here, rather than looking at RG flows of parameters, we consider the reparameterization-invariant flow of the manifold itself. To do this we numerically calculate the metric in the original parameters, taking care to use only information available after coarse-graining. We show that under coarse-graining the metric contracts very anisotropically, leading to a ``sloppy'' spectrum with the metric's Eigenvalues spanning many orders of magnitude. Our results give a qualitative explanation for the success of simple models: most directions in parameter space become fundamentally indistinguishable after coarse-graining.
Simulation Modeling and Performance Evaluation of Space Networks
Jennings, Esther H.; Segui, John
2006-01-01
In space exploration missions, the coordinated use of spacecraft as communication relays increases the efficiency of the endeavors. To conduct trade-off studies of the performance and resource usage of different communication protocols and network designs, JPL designed a comprehensive extendable tool, the Multi-mission Advanced Communications Hybrid Environment for Test and Evaluation (MACHETE). The design and development of MACHETE began in 2000 and is constantly evolving. Currently, MACHETE contains Consultative Committee for Space Data Systems (CCSDS) protocol standards such as Proximity-1, Advanced Orbiting Systems (AOS), Packet Telemetry/Telecommand, Space Communications Protocol Specification (SCPS), and the CCSDS File Delivery Protocol (CFDP). MACHETE uses the Aerospace Corporation s Satellite Orbital Analysis Program (SOAP) to generate the orbital geometry information and contact opportunities. Matlab scripts provide the link characteristics. At the core of MACHETE is a discrete event simulator, QualNet. Delay Tolerant Networking (DTN) is an end-to-end architecture providing communication in and/or through highly stressed networking environments. Stressed networking environments include those with intermittent connectivity, large and/or variable delays, and high bit error rates. To provide its services, the DTN protocols reside at the application layer of the constituent internets, forming a store-and-forward overlay network. The key capabilities of the bundling protocols include custody-based reliability, ability to cope with intermittent connectivity, ability to take advantage of scheduled and opportunistic connectivity, and late binding of names to addresses. In this presentation, we report on the addition of MACHETE models needed to support DTN, namely: the Bundle Protocol (BP) model. To illustrate the use of MACHETE with the additional DTN model, we provide an example simulation to benchmark its performance. We demonstrate the use of the DTN protocol
Modeling and simulation of ion channels and action potentials in taste receptor cells
Institute of Scientific and Technical Information of China (English)
CHEN PeiHua; LIU Xiaodong; ZHANG Wei; ZHOU Jun; WANG Ping; YANG Wei; LUO JianHong
2009-01-01
Based on patch clamp data on the ionic currents of rat taste receptor cells,a mathematical model of mammalian taste receptor cells was constructed to simulate the action potentials of taste receptor cells and their corresponding ionic components,including voltage-gated Na~+ currents and outward delayed rectifier K~+ currents.Our simulations reproduced the action potentials of taste receptor cells in response to electrical stimuli or sour tastants.The kinetics of ion channels and their roles in action potentials of taste receptor cells were also analyzed.Our prototype model of single taste receptor cell and simulation results presented in this paper provide the basis for the further study of taste information processing in the gustatory system.
Modeling and simulation of ion channels and action potentials in taste receptor cells
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Based on patch clamp data on the ionic currents of rat taste receptor cells, a mathematical model of mammalian taste receptor cells was constructed to simulate the action potentials of taste receptor cells and their corresponding ionic components, including voltage-gated Na+ currents and outward delayed rectifier K+ currents. Our simulations reproduced the action potentials of taste receptor cells in response to electrical stimuli or sour tastants. The kinetics of ion channels and their roles in action potentials of taste receptor cells were also analyzed. Our prototype model of single taste receptor cell and simulation results presented in this paper provide the basis for the further study of taste information processing in the gustatory system.
A Model for Predicting Thermomechanical Response of Large Space Structures.
1984-06-01
Dr. Tony Amos (202)767-4937 u.DD FORM 1473, 83 APR EDITION OF I JAN 73 IS OBSOLETE. SECURITY CLASSIFICATION CF THIS PAGE .. ’o 1 v A MODEL FOR...SYMBOL Dr. Tony Amos (202)767-4937 SDD FORM 1473, 83 APR E c , TION OF 1 JAN 73 ,S OBSOLETE. SECLUHITY (CLASSI. ICATION Oi) THI PAGE -i LARGE SPACE...94] for predicting the buckling loads associated with general instability of beam-like lattice trusses. Bazant and Christensen [95] present a
Mind the Gap: Exploring the Underground of the NASA Space Cancer Risk Model
Chappell, L. J.; Elgart, S. R.; Milder, C. M.; Shavers, M. R.; Semones, E. J.; Huff, J. L.
2017-01-01
) defines the knowledge gaps that impact our understanding of the cancer risks. These gaps are outlined in NASA's Human Research Roadmap [4], which identifies the research questions and actions recommended for reducing the uncertainty in the current NSCR model and for formulation of future models. The greatest contributors to uncertainty in the current model include radiation quality, dose rate effects, and the transfer of exposure-based risk from other populations to an astronaut population. Future formulations of the risk model may benefit from including other potential sources of uncertainty such as space dosimetry, errors in human epidemiology data, and the impact of microgravity and other spaceflight stressors. Here, we discuss the current capabilities of the NSCR-2012 model and several immediate research needs, highlighting areas expected to have an operational impact on the current model schema. The following subway-style route map outlines the NSCR-2012 model (Green Line), emphasizing the research gaps in the Human Research Roadmap for risk of radiation-induced carcinogenesis (Stops on Dashed Lines). The map diagrams how these research gaps feed specific portions of the model.
Terpstra, Teun; Lindell, Michael K.
2013-01-01
Although research indicates that adoption of flood preparations among Europeans is low, only a few studies have attempted to explain citizens' preparedness behavior. This article applies the Protective Action Decision Model (PADM) to explain flood preparedness intentions in the Netherlands. Survey data ("N" = 1,115) showed that…
Action and Language Mechanisms in the Brain: Data, Models and Neuroinformatics
DEFF Research Database (Denmark)
Arbib, Michael A.; Bonaiuto, James J.; Bornkessel-Schlesewsky, Ina
2014-01-01
We assess the challenges of studying action and language mechanisms in the brain, both singly and in relation to each other to provide a novel perspective on neuroinformatics, integrating the development of databases for encoding - separately or together - neurocomputational models and empirical...
Artist-Teachers' In-Action Mental Models While Teaching Visual Arts
Russo-Zimet, Gila
2017-01-01
Studies have examined the assumption that teachers have previous perceptions, beliefs and knowledge about learning (Cochran-Smith & Villegas, 2015). This study presented the In-Action Mental Model of twenty leading artist-teachers while teaching Visual Arts in three Israeli art institutions of higher Education. Data was collected in two…
Jarvis, Joy; Dickerson, Claire; Thomas, Kit; Graham, Sally
2014-01-01
This article presents the Action--Reflection--Modelling (ARM) pedagogical approach for teacher education developed during a Malaysia-UK collaborative project to construct a Bachelor of Education (Honours) degree programme in Primary Mathematics, with English and Health and Physical Education as minor subjects. The degree programme was written…
Teacher Educators' In-Action Mental Models in Different Teaching Situations
Mevorach, Miriam; Strauss, Sidney
2012-01-01
In previous studies on teachers' cognition, we discovered that teachers' teaching can be described via a general in-action mental model (IAMM) concerning the structure of the mind and the roles of teaching in fostering children's learning. The purpose of our study was to examine teacher educators' IAMM regarding student teachers' minds and…
Using the Knowledge to Action Process Model to Incite Clinical Change
Petzold, Anita; Korner-Bitensky, Nicol; Menon, Anita
2010-01-01
Introduction: Knowledge translation (KT) has only recently emerged in the field of rehabilitation with attention on creating effective KT interventions to increase clinicians' knowledge and use of evidence-based practice (EBP). The uptake of EBP is a complex process that can be facilitated by the use of the Knowledge to Action Process model. This…
Terpstra, Teun; Lindell, Michael K.
2013-01-01
Although research indicates that adoption of flood preparations among Europeans is low, only a few studies have attempted to explain citizens' preparedness behavior. This article applies the Protective Action Decision Model (PADM) to explain flood preparedness intentions in the Netherlands. Survey data ("N" = 1,115) showed that…
Classical and quantum mechanics of the nonrelativistic Snyder model in curved space
Mignemi, S
2011-01-01
The Snyder-de Sitter (SdS) model is a generalization of the Snyder model to a spacetime background of constant curvature. It is an example of noncommutative spacetime admitting two fundamental scales beside the speed of light, and is invariant under the action of the de Sitter group. Here, we consider its nonrelativistic counterpart, i.e. the Snyder model restricted to a three-dimensional sphere, and the related model obtained by considering the anti-Snyder model on a pseudosphere, that we call anti-Snyder-de Sitter (aSdS). We discuss the classical and the quantum mechanics of a free particle and of an oscillator in this framework. In analogy with the flat case, the properties of the SdS and aSdS model are rather different. In the SdS case, a lower bound on the localization in position and momentum space exists, which does not arise in the aSdS model. In both cases the energy of the harmonic oscillator acquires a dependence on the frequency, but the quantum mechanical aSdS oscillator admits only a finite numb...
Gonzales, Leslie D.
2015-01-01
In this article, readers are asked to suspend conventional notions of affirmative action as a policy that ensures equitable admissions practices to the nation's most elite post secondary institutions, and instead to consider how affirmative action might be understood as a way to challenge the relations of power that govern the legitimation of…
Space Weathering of Olivine: Samples, Experiments and Modeling
Keller, L. P.; Berger, E. L.; Christoffersen, R.
2016-01-01
Olivine is a major constituent of chondritic bodies and its response to space weathering processes likely dominates the optical properties of asteroid regoliths (e.g. S- and many C-type asteroids). Analyses of olivine in returned samples and laboratory experiments provide details and insights regarding the mechanisms and rates of space weathering. Analyses of olivine grains from lunar soils and asteroid Itokawa reveal that they display solar wind damaged rims that are typically not amorphized despite long surface exposure ages, which are inferred from solar flare track densities (up to 10 (sup 7 y)). The olivine damaged rim width rapidly approaches approximately 120 nm in approximately 10 (sup 6 y) and then reaches steady-state with longer exposure times. The damaged rims are nanocrystalline with high dislocation densities, but crystalline order exists up to the outermost exposed surface. Sparse nanophase Fe metal inclusions occur in the damaged rims and are believed to be produced during irradiation through preferential sputtering of oxygen from the rims. The observed space weathering effects in lunar and Itokawa olivine grains are difficult to reconcile with laboratory irradiation studies and our numerical models that indicate that olivine surfaces should readily blister and amorphize on relatively short time scales (less than 10 (sup 3 y)). These results suggest that it is not just the ion fluence alone, but other variable, the ion flux that controls the type and extent of irradiation damage that develops in olivine. This flux dependence argues for caution in extrapolating between high flux laboratory experiments and the natural case. Additional measurements, experiments, and modeling are required to resolve the discrepancies among the observations and calculations involving solar wind processing of olivine.
Model of strong stationary vortex turbulence in space plasmas
Directory of Open Access Journals (Sweden)
G. D. Aburjania
2009-01-01
Full Text Available This paper investigates the macroscopic consequences of nonlinear solitary vortex structures in magnetized space plasmas by developing theoretical model of plasma turbulence. Strongly localized vortex patterns contain trapped particles and, propagating in a medium, excite substantial density fluctuations and thus, intensify the energy, heat and mass transport processes, i.e., such vortices can form strong vortex turbulence. Turbulence is represented as an ensemble of strongly localized (and therefore weakly interacting vortices. Vortices with various amplitudes are randomly distributed in space (due to collisions. For their description, a statistical approach is applied. It is supposed that a stationary turbulent state is formed by balancing competing effects: spontaneous development of vortices due to nonlinear twisting of the perturbations' fronts, cascading of perturbations into short scales (direct spectral cascade and collisional or collisionless damping of the perturbations in the short-wave domain. In the inertial range, direct spectral cascade occurs through merging structures via collisions. It is shown that in the magneto-active plasmas, strong turbulence is generally anisotropic Turbulent modes mainly develop in the direction perpendicular to the local magnetic field. It is found that it is the compressibility of the local medium which primarily determines the character of the turbulent spectra: the strong vortex turbulence forms a power spectrum in wave number space. For example, a new spectrum of turbulent fluctuations in k^{−8/3} is derived which agrees with available experimental data. Within the framework of the developed model particle diffusion processes are also investigated. It is found that the interaction of structures with each other and particles causes anomalous diffusion in the medium. The effective coefficient of diffusion has a square root dependence on the stationary level of noise.
Musser, George
2015-01-01
What is space? It isn't a question that most of us normally stop to ask. Space is the venue of physics; it's where things exist, where they move and take shape. Yet over the past few decades, physicists have discovered a phenomenon that operates outside the confines of space and time. The phenomenon, the ability of one particle to affect another instantly across the vastness of space appears to be almost magical. Einstein grappled with this oddity and couldn't quite resolve it, describing it as "spooky action at a distance." But this strange occurrence has direct connections to black holes, particle collisions, and even the workings of gravity. If space isn't what we thought it was, then what is it? In Spooky Action at a Distance, George Musser sets out to answer that question, offering a provocative exploration of non locality and a celebration of the scientists who are trying to understand it. Musser guides us on an epic journey of scientific discovery into the lives of experimental physicists observing par...
Initial Condition Model from Imaginary Part of Action and the Information Loss
Nielsen, H B
2009-01-01
We review slightly a work by Horowitz and Maldecena solving the information loss problem for black holes by having inside the blackhole - near to the singularity - a boundary condition, as e.g the no boundary proposal by Hartle and Hawking. Here we propose to make this boundary condition come out of our imaginary action model (together with Masao Ninomiya). This model naturally begins effectively to set up boundaries - whether it be in future or past! - especially strongly whenever we reach to high energy physics regimes, such as near the black hole singularity, or in Higgs producing machines as LHC or SSC. In such cases one can say our model predicts miracles. The point is that you may say that the information loss problem, unless you solve it in other ways, call for such a violation of time causality as in our imaginary action model!
The Harari Shupe preon model and nonrelativistic quantum phase space
Żenczykowski, P.
2008-03-01
We propose that the whole algebraic structure of the Harari-Shupe rishon model originates via a Dirac-like linearization of quadratic form x2 +p2, with position and momentum satisfying standard commutation relations. The scheme does not invoke the concept of preons as spin-1/2 subparticles, thus evading the problem of preon confinement, while fully explaining all symmetries emboded in the Harari-Shupe model. Furthermore, the concept of quark colour is naturally linked to the ordering of rishons. Our scheme leads to group U (1) ⊗ SU (3) combined with SU (2), with two of the SU (2) generators not commuting with reflections. An interpretation of intra-generation quark-lepton transformations in terms of genuine rotations and reflections in phase space is proposed.
Poss, J E
2001-06-01
This article discusses the development of a new model representing the synthesis of two models that are often used to study health behaviors: the Health Belief Model and the Theory of Reasoned Action. The new model was developed as the theoretic framework for an investigation of the factors affecting participation by Mexican migrant workers in tuberculosis screening. Development of the synthesized model evolved from the concern that models used to investigate health-seeking behaviors of mainstream Anglo groups in the United States might not be appropriate for studying migrant workers or persons from other cultural backgrounds.
Automated photogrammetry for three-dimensional models of urban spaces
Leberl, Franz; Meixner, Philipp; Wendel, Andreas; Irschara, Arnold
2012-02-01
The location-aware Internet is inspiring intensive work addressing the automated assembly of three-dimensional models of urban spaces with their buildings, circulation spaces, vegetation, signs, even their above-ground and underground utility lines. Two-dimensional geographic information systems (GISs) and municipal utility information exist and can serve to guide the creation of models being built with aerial, sometimes satellite imagery, streetside images, indoor imaging, and alternatively with light detection and ranging systems (LiDARs) carried on airplanes, cars, or mounted on tripods. We review the results of current research to automate the information extraction from sensor data. We show that aerial photography at ground sampling distances (GSD) of 1 to 10 cm is well suited to provide geometry data about building facades and roofs, that streetside imagery at 0.5 to 2 cm is particularly interesting when it is collected within community photo collections (CPCs) by the general public, and that the transition to digital imaging has opened the no-cost option of highly overlapping images in support of a more complete and thus more economical automation. LiDAR-systems are a widely used source of three-dimensional data, but they deliver information not really superior to digital photography.
Discrete model of spacetime in terms of inverse spectra of the $T_0$ Alexandroff topological spaces
Efremov, V N; Efremov, Vladimir N.; Mitskievich, Nikolai V.
2003-01-01
The theory of inverse spectra of $T_0$ Alexandroff topological spaces is used to construct a model of $T_0$-discrete four-dimensional spacetime. The universe evolution is interpreted in terms of a sequence of topology changes in the set of $T_0$-discrete spaces realized as nerves of the canonical partitions of three-dimensional compact manifolds. The cosmological time arrow arises being connected with the refinement of the canonical partitions, and it is defined by the action of homomorphisms in the proper inverse spectrum of three-dimensional $T_0$-discrete spaces. A new causal order relation in this spectrum is postulated having the basic properties of the causal order in the pseudo-Riemannian spacetime however also bearing certain quasi-quantum features. An attempt is made to describe topological changes between compact manifolds in terms of bifurcations of proper inverse spectra; this led us to the concept of bispectrum. As a generalization of this concept, inverse multispectra and superspectrum are intro...
Assembly interruptability robustness model with applications to Space Station Freedom
Wade, James William
1991-02-01
Interruptability robustness of a construction project together with its assembly sequence may be measured by calculating the probability of its survival and successful completion in the face of unplanned interruptions of the assembly process. Such an interruption may jeopardize the survival of the structure being assembled, the survival of the support equipment, and/or the safety of the members of the construction crew, depending upon the stage in the assembly sequence when the interruption occurs. The interruption may be due to a number of actors such as: machinery break-downs, environmental damage, worker emergency illness or injury, etc. Each source of interruption has a probability of occurring, and adds an associated probability of loss, schedule delay, and cost to the project. Several options may exist for reducing the consequences of an interruption at a given point in the assembly sequence, including altering the assembly sequence, adding extra components or equipment as interruptability 'insurance', increasing the capability of support facilities, etc. Each option may provide a different overall performance of the project as it relates to success, assembly time, and project cost. The Interruptability Robustness Model was devised and provides a method which allows the overall interruptability robustness of construction of a project design and its assembly sequence to be quantified. In addition, it identifies the susceptibility to interruptions for the assembly sequence at all points within the assembly sequence. The model is applied to the present problem of quantifying and improving interruptability robustness during the construction of Space Station Freedom. This application was used as a touchstone for devising the Interruptability Robustness Model. However, the model may be utilized to assist in the analysis of interruptability robustness for other space-related construction projects such as the lunar base and orbital assembly of the manned Mars
Health Belief Model and Reasoned Action Theory in Predicting Water Saving Behaviors in Yazd, Iran
Mohammad Taghi Ghaneian; Mahdieh Momayyezi; Mohammad Ali Morowatisharifabad
2012-01-01
Background: People's behaviors and intentions about healthy behaviors depend on their beliefs, values, and knowledge about the issue. Various models of health education are used in deter-mining predictors of different healthy behaviors but their efficacy in cultural behaviors, such as water saving behaviors, are not studied. The study was conducted to explain water saving beha-viors in Yazd, Iran on the basis of Health Belief Model and Reasoned Action Theory. Methods: The cross-sectional stud...
DEFF Research Database (Denmark)
Smets, Barth F.; Lardon, Laurent
2009-01-01
of the outcomes to the various plasmid dynamic parameters. For our analysis, we developed a set of user-friendly MatLab® routines, which are deposited in the public domain. We hope that the availability of these routines will encourage the computationally untrained microbiologist to make use of these mathematical...... models. Finally, further permutations, as well as limitations of these mass action models in view of the structured complexity of most microbial systems are addressed....
Romanov, Evgenii Dmitrievich
2016-08-01
A family of quasi-invariant measures on the special functional space of curves in a finite-dimensional Euclidean space with respect to the action of diffeomorphisms is constructed. The main result is an explicit expression for the Radon-Nikodym derivative of the transformed measure relative to the original one. The stochastic Ito integral allows to express the result in an invariant form for a wider class of diffeomorphisms. These measures can be used to obtain irreducible unitary representations of the diffeomorphisms group which will be studied in future research. A geometric interpretation of the action considered together with a generalization to the multidimensional case makes such representations applicable to problems of quantum mechanics.
Cross-Compiler for Modeling Space-Flight Systems
James, Mark
2007-01-01
Ripples is a computer program that makes it possible to specify arbitrarily complex space-flight systems in an easy-to-learn, high-level programming language and to have the specification automatically translated into LibSim, which is a text-based computing language in which such simulations are implemented. LibSim is a very powerful simulation language, but learning it takes considerable time, and it requires that models of systems and their components be described at a very low level of abstraction. To construct a model in LibSim, it is necessary to go through a time-consuming process that includes modeling each subsystem, including defining its fault-injection states, input and output conditions, and the topology of its connections to other subsystems. Ripples makes it possible to describe the same models at a much higher level of abstraction, thereby enabling the user to build models faster and with fewer errors. Ripples can be executed in a variety of computers and operating systems, and can be supplied in either source code or binary form. It must be run in conjunction with a Lisp compiler.
A mediation model of individual differences in attitudes toward affirmative actions for women.
Moscoso, Silvia; García-Izquierdo, Antonio L; Bastida, María
2012-06-01
A mediation model of the relation between gender and attitudes toward affirmative action in favor of working women was tested. Four mediation variables were considered: perceived unfairness in the situation of working women, perceived threat to the non-designated group (men), self-esteem, and gender self-concept (masculinity and femininity). 192 women and 128 men, with differing occupations, participated. Gender affects individuals' attitudes toward affirmative actions for women, mediated by perceived unfairness in the situation of working women, perceived threat to the non-designated group, and feminine self-concept. Implications for research and practice are discussed.
Baldassarre, Gianluca; Mannella, Francesco; Fiore, Vincenzo G; Redgrave, Peter; Gurney, Kevin; Mirolli, Marco
2013-05-01
Reinforcement (trial-and-error) learning in animals is driven by a multitude of processes. Most animals have evolved several sophisticated systems of 'extrinsic motivations' (EMs) that guide them to acquire behaviours allowing them to maintain their bodies, defend against threat, and reproduce. Animals have also evolved various systems of 'intrinsic motivations' (IMs) that allow them to acquire actions in the absence of extrinsic rewards. These actions are used later to pursue such rewards when they become available. Intrinsic motivations have been studied in Psychology for many decades and their biological substrates are now being elucidated by neuroscientists. In the last two decades, investigators in computational modelling, robotics and machine learning have proposed various mechanisms that capture certain aspects of IMs. However, we still lack models of IMs that attempt to integrate all key aspects of intrinsically motivated learning and behaviour while taking into account the relevant neurobiological constraints. This paper proposes a bio-constrained system-level model that contributes a major step towards this integration. The model focusses on three processes related to IMs and on the neural mechanisms underlying them: (a) the acquisition of action-outcome associations (internal models of the agent-environment interaction) driven by phasic dopamine signals caused by sudden, unexpected changes in the environment; (b) the transient focussing of visual gaze and actions on salient portions of the environment; (c) the subsequent recall of actions to pursue extrinsic rewards based on goal-directed reactivation of the representations of their outcomes. The tests of the model, including a series of selective lesions, show how the focussing processes lead to a faster learning of action-outcome associations, and how these associations can be recruited for accomplishing goal-directed behaviours. The model, together with the background knowledge reviewed in the paper
Equivalence and Differences between Structural Equation Modeling and State-Space Modeling Techniques
Chow, Sy-Miin; Ho, Moon-ho R.; Hamaker, Ellen L.; Dolan, Conor V.
2010-01-01
State-space modeling techniques have been compared to structural equation modeling (SEM) techniques in various contexts but their unique strengths have often been overshadowed by their similarities to SEM. In this article, we provide a comprehensive discussion of these 2 approaches' similarities and differences through analytic comparisons and…
Equivalence and differences between structural equation modeling and state-space modeling techniques
Chow, Sy-Miin; Ho, Moon-ho R.; Hamaker, E.L.; Dolan, C.V.
2010-01-01
State-space modeling techniques have been compared to structural equation modeling (SEM) techniques in various contexts but their unique strengths have often been overshadowed by their similarities to SEM. In this article, we provide a comprehensive discussion of these 2 approaches' similarities and