Tracking in Object Action Space
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...... space of the object affordances, i.e., the space of possible actions that are applied on a given object. This way, 3D body tracking reduces to action tracking in the object (and context) primed parameter space of the object affordances. This reduces the high-dimensional joint-space to a low...
Gauged WZW models for space-time groups and gravitational actions
Mora, Pablo; Pais, Pablo(Centro de Estudios Científicos (CECS), Av. Arturo Prat 514, Valdivia, Chile); Willison, Steven
2011-01-01
In this paper we investigate gauged Wess-Zumino-Witten models for space-time groups as gravitational theories, following the trend of recent work by Anabalon, Willison and Zanelli. We discuss the field equations in any dimension and study in detail the simplest case of two space-time dimensions and gauge group SO(2,1). For this model we study black hole solutions and we calculate their mass and entropy which resulted in a null value for both.
Learning Actions Models: Qualitative Approach
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...... methods suited for finite identifiability of particular types of deterministic actions....
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…
Deep Reinforcement Learning in Parameterized Action Space
Hausknecht, Matthew; Stone, Peter
2015-01-01
Recent work has shown that deep neural networks are capable of approximating both value functions and policies in reinforcement learning domains featuring continuous state and action spaces. However, to the best of our knowledge no previous work has succeeded at using deep neural networks in structured (parameterized) continuous action spaces. To fill this gap, this paper focuses on learning within the domain of simulated RoboCup soccer, which features a small set of discrete action types, ea...
Reinforcement Learning in Continuous Action Spaces
Hasselt, H. van; Wiering, M.A.
2007-01-01
Quite some research has been done on Reinforcement Learning in continuous environments, but the research on problems where the actions can also be chosen from a continuous space is much more limited. We present a new class of algorithms named Continuous Actor Critic Learning Automaton (CACLA) that can handle continuous states and actions. The resulting algorithm is straightforward to implement. An experimental comparison is made between this algorithm and other algorithms that can handle cont...
Reinforcement Learning in Continuous Action Spaces
Hasselt, H. van; Wiering, M.A.
2007-01-01
Quite some research has been done on Reinforcement Learning in continuous environments, but the research on problems where the actions can also be chosen from a continuous space is much more limited. We present a new class of algorithms named Continuous Actor Critic Learning Automaton (CACLA) that c
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...
Juhl, Joakim
This thesis is about mathematical modelling and technology development. While mathematical modelling has become widely deployed within a broad range of scientific practices, it has also gained a central position within technology development. The intersection of mathematical modelling and...... generated. Structured around the intersections of certainty, agency, and dependences, the thesis’ findings are in chapter 9 extended to a discussion of the theoretical fundament through which we interpret the regulation project and its use of modelling. I demonstrate a novel framework that I term...
Reinforcement learning in continuous state and action spaces
Hasselt, H. van; Wiering, M.A.; Otterlo, M. van
2012-01-01
Many traditional reinforcement-learning algorithms have been designed for problems with small finite state and action spaces. Learning in such discrete problems can been difficult, due to noise and delayed reinforcements. However, many real-world problems have continuous state or action spaces, whic
Creating Space: Engaging Deliberation about Climate Action
Phear, Nicolette
In the United States public discourse, climate change is often framed as a polarized and intractable issue. The purpose of this dissertation was to explore deliberation about climate action, and to evaluate whether effective responses to climate change can be facilitated through new structures and processes that enable and encourage dialogue on the subject of how to reduce greenhouse gas emissions. Working with sustainability leaders at the University of Montana and in the community of Missoula, Montana, the author convened three public deliberations, in which a variety of solutions to climate change were discussed. Three questions guided this study: 1) what motivated individuals to engage in deliberation about climate action; 2) how did individual engagement vary and affect the quality of the deliberation; and 3) how effective were the deliberations in building a sense of individual agency and generating collaborative action strategies to address climate change. Based on a rigorous statistical analysis of survey responses combined with qualitative data, this action research study offers a holistic exploration of the three deliberative events convened. The deliberative processes generated collaborative action strategies and increased participants' sense of agency to take action on climate change; the findings also revealed differences in the ways individuals engaged and affected the quality of the overall group deliberation. This dissertation contributes to the literature on collaborative responses and collective action on climate change, broadens understanding of deliberative processes, and provides new insight into opportunities for leading deliberation about climate action.
Pro-torus actions on Poincar\\'e duality spaces
Özkurt, Ali; Dönmez, Doğan
2006-01-01
In this paper, it is shown that some of the results of torus actions on Poincar\\'{e} duality spaces, Borel's dimension formula and topological splitting principle to local weights, hold if `torus' is replaced by `pro-torus'.
Actions of certain arithmetic groups on Gromov hyperbolic spaces
Manning, Jason Fox
2007-01-01
We study the variety of actions of a fixed (Chevalley) group on arbitrary geodesic, Gromov hyperbolic spaces. In high rank we obtain a complete classification. In rank one, we obtain some partial results and give a conjectural picture.
Reinforcement learning in continuous state and action spaces
Hasselt, van, F.N.; Wiering, M.A.; Otterlo, van, M.
2012-01-01
Many traditional reinforcement-learning algorithms have been designed for problems with small finite state and action spaces. Learning in such discrete problems can been difficult, due to noise and delayed reinforcements. However, many real-world problems have continuous state or action spaces, which can make learning a good decision policy even more involved. In this chapter we discuss how to automatically find good decision policies in continuous domains. Because analytically computing a go...
Iglesias Turrión, Pablo
2004-01-01
This paper is about the new social movements against the Globalisation. In particular, I will speak about the period between the demonstrations of Seattle (November/December 99) and the demonstrations of Genoa (June 2001) and the sector of movement that have practiced strategies of civil disobedience and conflict with the police forces. In this period, it has been developed a particular new form of collective action that I've called model anti-summit. The relationship with mass media and the ...
Space for action: How practitioners influence environmental assessment
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
Space for action: How practitioners influence environmental assessment
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.
Unsupervised action classification using space-time link analysis
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 metho...
Collective action and rationality models
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.
Quantum action principle in curved space
Schwinger's action principle is formulated for the quantum system which corresponds to the classical system described by the Lagrangian L/sub c/(x,x) = (M/2)g/sub ij/(x)x/sup i/x/sup j/ -- v(x). It is sufficient for the purpose of deriving the laws of quantum mechanics to consider only c-number variations of coordinates and time. The Euler--Lagrange equation, the canonical commutation relations, and the canonical equations of motion are derived from this principle in a consistent manner. Further, it is shown that an arbitrary point transformation leaves the forms of the fundamental equations invariant. The judicious choice of the quantal Lagrangian is essential in the formulation. A quantum mechanical analog of Noether's theorem, which relates the invariance of the quantal action with a conservation law is established. The ambiguities in the quantal Lagrangian are also discussed, and it is pointed out that the requirement of invariance is not sufficient to determine uniquely the quantal Lagrangian and the Hamiltonian
MHD dynamo action in space plasmas
Electric currents are now recognized to play a major role in the physical process of the Earths magnetosphere as well as in distant astrophysical plasmas. In driving these currents MHD dynamos as well as generators of a thermoelectric nature are important. The primary source of power for the Earths magnetospheric process is the solar wind, which supplies a voltage of the order of 200 kV across the magnetosphere. The direction of the large-scale solar wind electric field varies of many different time scales. The power input to the magnetosphere is closely correlated with the direction of the large-scale solar wind electric field in such a fashion as to mimick the response of a half-wave rectifier with a down-to-dusk conduction direction. Behind this apparently simple response there are complex plasma physical processes that are still very incompletely understood. They are intimately related to auroras, magnetic storms, radiation belts and changes in magnetospheric plasma populations. Similar dynamo actions should occur at other planets having magnetospheres. Recent observations seem to indicate that part of the power input to the Earths magnetosphere comes through MHD dynamo action of a forced plasma flow inside the flanks of the magnetopause and may play a role in other parts of the magnetosphere, too. An example of a cosmical MHD connected to a solid load is the corotating plasma of Jupiters inner magnetosphere, sweeping past the plants inner satelites. In particular the electric currents thereby driven to and from the satellite Io have attracted considerable interest.(author)
Nichols, Barry D.; Dracopoulos, Dimitris C.
2014-01-01
An algorithm based on Newton’s Method is proposed for action selection in continuous state- and action-space reinforcement learning without a policy network or discretization. The proposed method is validated on two benchmark problems: Cart-Pole and double Cart-Pole on which the proposed method achieves comparable or improved performance with less parameters to tune and in less training episodes than CACLA, which has previously been shown to outperform many other continuous state- and action-...
On algebraic spaces with an action of G_m
Drinfeld, Vladimir
2013-01-01
Let Z be an algebraic space of finite type over a field, equipped with an action of the multiplicative group $G_m$. In this situation we define and study a certain algebraic space equipped with an unramified morphism to $A^1\\times Z\\times Z$, where $A^1$ is the affine line. (If Z is affine and smooth this is just the closure of the graph of the action map $G_m\\times Z\\to Z$.) In articles joint with D.Gaitsgory we use this set-up to prove a new result in the geometric theory of automorphic for...
Invariant effective actions, cohomology of homogeneous spaces and anomalies
D`Hoker, E. [California Univ., Los Angeles, CA (United States). Dept. of Physics
1995-10-02
We construct the most general local effective actions for Goldstone boson fields associated with spontaneous symmetry breakdown from a group G to a subgroup H. In a preceding paper, it was shown that any G-invariant term in the action, which results from a non-invariant Lagrangian density, corresponds to a non-trivial generator of the de Rham cohomology classes of G/H. Here, we present an explicit construction of all the generators of this cohomology for any coset space G/H and compact, connected group G. Generators contributing to actions in 4-dimensional space-time arise either as products of generators of lower degree such as the Goldstone-Wilczek current, or are of the Wess-Zumino-Witten type. The latter arise if and only if G has a non-zero G-invariant symmetric d-symbol, which vanishes when restricted to the subgroup H, i.e. when G has anomalous representations in which H is embedded in an anomaly free way. Coupling of additional gauge fields leads to actions whose gauge variation coincides with the chiral anomaly, which is carried here by Goldstone boson fields at tree level. Generators contributing to actions in 3-dimensional space-time arise as Chern-Simons terms evaluated on connections that are composites of the Goldstone field. (orig.).
Invariant effective actions, cohomology of homogeneous spaces and anomalies
We construct the most general local effective actions for Goldstone boson fields associated with spontaneous symmetry breakdown from a group G to a subgroup H. In a preceding paper, it was shown that any G-invariant term in the action, which results from a non-invariant Lagrangian density, corresponds to a non-trivial generator of the de Rham cohomology classes of G/H. Here, we present an explicit construction of all the generators of this cohomology for any coset space G/H and compact, connected group G. Generators contributing to actions in 4-dimensional space-time arise either as products of generators of lower degree such as the Goldstone-Wilczek current, or are of the Wess-Zumino-Witten type. The latter arise if and only if G has a non-zero G-invariant symmetric d-symbol, which vanishes when restricted to the subgroup H, i.e. when G has anomalous representations in which H is embedded in an anomaly free way. Coupling of additional gauge fields leads to actions whose gauge variation coincides with the chiral anomaly, which is carried here by Goldstone boson fields at tree level. Generators contributing to actions in 3-dimensional space-time arise as Chern-Simons terms evaluated on connections that are composites of the Goldstone field. (orig.)
Pro-Torus Actions on Poincaré Duality Spaces
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’.
Introduction. Modelling natural action selection
Tony J Prescott; Bryson, Joanna J; Seth, Anil K.
2007-01-01
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 s...
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
A Note on the Derivation of Wave Action Balance Equation in Frequency Space
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.
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.
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. PMID:12850025
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.
State Space Modeling Using SAS
Rajesh Selukar
2011-01-01
This article provides a brief introduction to the state space modeling capabilities in SAS, a well-known statistical software system. SAS provides state space modeling in a few different settings. SAS/ETS, the econometric and time series analysis module of the SAS system, contains many procedures that use state space models to analyze univariate and multivariate time series data. In addition, SAS/IML, an interactive matrix language in the SAS system, provides Kalman filtering and smoothing ro...
The What, Who, and How of Ecological Action Space
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.
Abstract Action Potential Models for Toxin Recognition
Peterson, James; Khan, Taufiquar
2005-01-01
In this paper, we present a robust methodology using mathematical pattern recognition schemes to detect and classify events in action potentials for recognizing toxins in biological cells. We focus on event detection in action potential via abstraction of information content into a low dimensional feature vector within the constrained computational environment of a biosensor. We use generated families of action potentials from a classic Hodgkin–Huxley model to verify our methodology and build...
Target Space Supersymmetric $\\sigma$ Model Techniques
De Boer, J; Boer, Jan de; Skenderis, Kostas
1996-01-01
We briefly review the covariant formulation of the Green-Schwarz superstring by Berkovits, and describe how a detailed tree-level and one-loop analysis of this model leads, for the first time, to a derivation of the low-energy effective action of the heterotic superstring while keeping target-space supersymmetry manifest. The resulting low-energy theory is old-minimal supergravity coupled to tensor multiplet. The dilaton is part of the compensator multiplet.
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
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…
A learning oriented subjective action space as an indicator of giftedness
ALBERT ZIEGLER
2008-06-01
Full Text Available Traditionally, in giftedness research, the intelligence quotient has been presumed to be the best predictor of high achievement levels. From the perspective of the Actiotope Model of Giftedness, however, it is merely one indicator among several on the effectiveness of the academic action repertoire. In this model, learning is considered to be more important than personal traits for attaining high levels of achievement. This is confirmed with three studies conducted with pupils in grades 8 through 11. In Study 1 it was shown that high achieving pupils in the subject of mathematics can be differentiated from other pupils according to the learning orientation of their subjective action space. High achievement can be better predicted over a temporal distance of six months through the learning orientation of the subjective action space than through intelligence. This finding was replicated in Study 2 for the scholastic subject of biology. In Study 3, an investigation was undertaken to determine whether the performance enhancing effect of a learning oriented subjective action space is also beneficial in coming to terms with experiences of failure. This premise could also be confirmed.
The Character of Space – Describing aspects of space in live action role-play
Karls, Anders
2014-01-01
This paper aims to identify and briefly describe the central aspects of performance space in live action role-play (larp). It begins by introducing the reader to the phenomenon of larp and relating it to other performance arts. It opens up the concept of the magic circle of play and illustrates the different levels of reality and fiction experienced within larp in order to build a base for understanding larp space. Finally it contains the author’s personal reflections over the performance spa...
Large space shell model calculations with small space results
Zamick, Larry; Yu, Xiafei
2015-01-01
We note that in large space shell model calculaiotns and experiment one sometimes get results, the form of which also appear in smaller space calculations. On the other hand there are some results which demand the large space approach.
Action of space charge on aging and breakdown of polymers
无
2001-01-01
The study on how space charges affect aging and breakdown of polymers becomes one of the most important domains. Most of the models are based on the injected charges increasing the local field to induce the breakdown of polymers and breaking the large molecule chains. These models ignore the effects of space charge on the microstruc-ture of dielectric materials. In this review, with the calcula-tion of the electromagnetic energy and the electromechanical energy around a trapped charge and with some new experi-mental results, it is proved that aging and breakdown in polymers are caused during the detrapping of the trapped charges. Aging and breakdown of the polymers are related to the release of the electromechanical energy around trapped charges.
Disentangling Action from Social Space: Tool-Use Differently Shapes the Space around Us
Iachini, Tina; Farnè, Alessandro; Frassinetti, Francesca
2016-01-01
Converging evidence suggests close relationships between the action and social space representations. The concepts of peripersonal space, as defined by cognitive neuroscience, and interpersonal space, as defined by social psychology, refer to approximately the same spatial area surrounding our bodies. The aim of this study was thus to assess experimentally whether the peripersonal (PPS) and interpersonal space (IPS) represent a similar psychological entity. Were this true, they should share some functional features. Here we tested tool-use dependent plasticity, known to modulate PPS, but still unexplored in the IPS. Results from two experiments converge in showing that tool-use remapped the action-related PPS, measured by a Reaching-distance toward a confederate, but did not affect the social-related IPS, measured by a Comfort-distance task. These findings indicate that PPS and IPS rely on dissociable plastic mechanisms and suggest that, at least in the present experimental conditions, there is no full functional overlap between these two spatial representations. PMID:27144720
Diffeomorphisms as symplectomorphisms in history phase space: Bosonic string model
The structure of the history phase space G of a covariant field system and its history group (in the sense of Isham and Linden) is analyzed on an example of a bosonic string. The history space G includes the time map T from the spacetime manifold (the two-sheet) Y to a one-dimensional time manifold T as one of its configuration variables. A canonical history action is posited on G such that its restriction to the configuration history space yields the familiar Polyakov action. The standard Dirac-ADM action is shown to be identical with the canonical history action, the only difference being that the underlying action is expressed in two different coordinate charts on G. The canonical history action encompasses all individual Dirac-ADM actions corresponding to different choices T of foliating Y. The history Poisson brackets of spacetime fields on G induce the ordinary Poisson brackets of spatial fields in the instantaneous phase space G0 of the Dirac-ADM formalism. The canonical history action is manifestly invariant both under spacetime diffeomorphisms Diff Y and temporal diffeomorphisms Diff T. Both of these diffeomorphisms are explicitly represented by symplectomorphisms on the history phase space G. The resulting classical history phase space formalism is offered as a starting point for projection operator quantization and consistent histories interpretation of the bosonic string model
Space environment model construction technology
Nishimoto, Hironobu; Matsumoto, Haruhisa
1992-08-01
A space environment model was constructed based on the results of the review on space environment model conducted in Fiscal Year 1986 and 1987. The space environment model was constructed to collect theories and data required for grasping various physical entities such as radiation, plasma, and spacecraft fragments and so forth, and to enable quantitative prediction of their time wise, spacial distribution and their effects such as electrification and material deterioration, and its system structure and functions were shown. The Technical Data Acquisition Equipment (TEDA) installed onboard the Engineering Test Satellite-5 (ETS-5) consist of various satellite environment monitors and component and material deterioration monitors for the purpose of acquiring technical data required for design and evaluation for satellite development. Review was conducted to clarify the correlation between each TEDA data and to apply the result in constructing the satellite environment model. Correlation between each TEDA data was made clear.
Effective action for the Abelian Higgs model in FLRW
George, Damien P; Postma, Marieke
2012-01-01
We compute the divergent contributions to the one-loop action of the U(1) Abelian Higgs model. The calculation allows for a Friedmann-Lemaitre-Robertson-Walker space-time and a time-dependent expectation value for the scalar field. Treating the time-dependent masses as two-point interactions, we use the in-in formalism to compute the first, second and third order graphs that contribute quadratic and logarithmic divergences to the effective scalar action. Working in R-xi gauge we show that the result is gauge invariant upon using the equations of motion.
Effective action for the Abelian Higgs model in FLRW
George, Damien P.; Mooij, Sander(Nikhef, Science Park 105, Amsterdam, 1098 XG The Netherlands); Postma, Marieke
2012-01-01
We compute the divergent contributions to the one-loop action of the U(1) Abelian Higgs model. The calculation allows for a Friedmann-Lemaitre-Robertson-Walker space-time and a time-dependent expectation value for the scalar field. Treating the time-dependent masses as two-point interactions, we use the in-in formalism to compute the first, second and third order graphs that contribute quadratic and logarithmic divergences to the effective scalar action. Working in R-xi gauge we show that the...
Simplicial models of trace spaces
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...... variation of the end points. The original motivation stems from certain models for concurrent computation. So far, homotopy types of 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...
Belehaki Anna; Messerotti Mauro; Candidi Maurizio
2014-01-01
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 Spa...
A statistical model of future human actions
A critical review has been carried out of models of future human actions during the long term post-closure period of a radioactive waste repository. Various Markov models have been considered as alternatives to the standard Poisson model, and the problems of parameterisation have been addressed. Where the simplistic Poisson model unduly exaggerates the intrusion risk, some form of Markov model may have to be introduced. This situation may well arise for shallow repositories, but it is less likely for deep repositories. Recommendations are made for a practical implementation of a computer based model and its associated database. (Author)
Action Research to Improve the Learning Space for Diagnostic Techniques
Ellen Ariel
2015-08-01
Full Text Available The module described and evaluated here was created in response to perceived learning difficulties in diagnostic test design and interpretation for students in third-year Clinical Microbiology. Previously, the activities in lectures and laboratory classes in the module fell into the lower cognitive operations of “knowledge” and “understanding.” The new approach was to exchange part of the traditional activities with elements of interactive learning, where students had the opportunity to engage in deep learning using a variety of learning styles. The effectiveness of the new curriculum was assessed by means of on-course student assessment throughout the module, a final exam, an anonymous questionnaire on student evaluation of the different activities and a focus group of volunteers. Although the new curriculum enabled a major part of the student cohort to achieve higher pass grades (p < 0.001, it did not meet the requirements of the weaker students, and the proportion of the students failing the module remained at 34%. The action research applied here provided a number of valuable suggestions from students on how to improve future curricula from their perspective. Most importantly, an interactive online program that facilitated flexibility in the learning space for the different reagents and their interaction in diagnostic tests was proposed. The methods applied to improve and assess a curriculum refresh by involving students as partners in the process, as well as the outcomes, are discussed.
Spectral action models of gravity on packed swiss cheese cosmology
Ball, Adam; Marcolli, Matilde
2016-06-01
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 expansion on a space obtained as an Apollonian packing of three-dimensional spheres inside a four-dimensional ball. Using information from the zeta function of the Dirac operator of the spectral triple, we compute the leading terms in the asymptotic expansion of the spectral action. They consist of a zeta regularization of the divergent sum of the leading terms of the spectral actions of the individual spheres in the packing. This accounts for the contribution of points 1 and 3 in the dimension spectrum (as in the case of a 3-sphere). There is an additional term coming from the residue at the additional point in the real dimension spectrum that corresponds to the packing constant, as well as a series of fluctuations coming from log-periodic oscillations, created by the points of the dimension spectrum that are off the real line. These terms detect the fractality of the residue set of the sphere packing. We show that the presence of fractality influences the shape of the slow-roll potential for inflation, obtained from the spectral action. We also discuss the effect of truncating the fractal structure at a certain scale related to the energy scale in the spectral action.
New considerations on Hilbert action and Einstein equations in anisotropic spaces
Voicu, Nicoleta
2009-01-01
We find the generalization of Einstein equations to Finsler spaces by variational means and, based on the invariance of the Finslerian Hilbert action to infinitesimal transformations, we find the analogue of the energy- momentum conservation law in these spaces.
Modeling video evolution for action recognition
Fernando, Basura; Gavves, Stratis; Oramas Mogrovejo, José Antonio; Ghodrati, Amir; Tuytelaars, Tinne
2015-01-01
Fernando B., Gavves E., Oramas Mogrovejo J., Ghodrati A., Tuytelaars T., ''Modeling video evolution for action recognition'', 28th IEEE conference on computer vision and pattern recognition - CVPR 2015, pp. 5378-5387, June 7-12, 2015, Boston, Massachusetts, USA.
Public Health Action Model for Cancer Survivorship.
Moore, Angela R; Buchanan, Natasha D; Fairley, Temeika L; Lee Smith, Judith
2015-12-01
Long-term objectives associated with cancer survivors have been suggested by Healthy People 2020, including increasing the proportion of survivors living beyond 5 years after diagnosis and improving survivors' mental and physical health-related quality of life. Prior to reaching these objectives, several intermediate steps must be taken to improve the physical, social, emotional, and financial well-being of cancer survivors. Public health has a role in developing strategic, actionable, and measurable approaches to facilitate change at multiple levels to improve the lives of survivors and their families. The social ecological model has been used by the public health community as the foundation of multilevel intervention design and implementation, encouraging researchers and practitioners to explore methods that promote internal and external changes at the individual, interpersonal, organizational, community, and policy levels. The survivorship community, including public health professionals, providers, policymakers, survivors, advocates, and caregivers, must work collaboratively to identify, develop, and implement interventions that benefit cancer survivors. The National Action Plan for Cancer Survivorship highlights public health domains and associated strategies that can be the impetus for collaboration between and among the levels in the social ecological model and are integral to improving survivor outcomes. This paper describes the Public Health Action Model for Cancer Survivorship, an integrative framework that combines the National Action Plan for Cancer Survivorship with the social ecological model to demonstrate how interaction among the various levels may promote better outcomes for survivors. PMID:26590641
Parametrized spaces model locally constant homotopy sheaves
Shulman, Michael A.
2007-01-01
We prove that the homotopy theory of parametrized spaces embeds fully and faithfully in the homotopy theory of simplicial presheaves, and that its essential image consists of the locally homotopically constant objects. This gives a homotopy-theoretic version of the classical identification of covering spaces with locally constant sheaves. We also prove a new version of the classical result that spaces parametrized over X are equivalent to spaces with an action of the loop space of X. This giv...
Boundary action of the H+3 model
We find the boundary action for Euclidean AdS2 D-branes in H+3. This action is consistent with the D-branes' symmetries and with the H+3-Liouville relation for disc correlators. It can be used for performing free-field calculations in the H+3 model with boundaries. We explicitly perform the Coulomb-like integrals which appear in the free-field calculation of the bulk one-point function, and find agreement with previously known conformal bootstrap results
Boundary action of the H3+ model
Fateev, V
2008-01-01
We find the boundary action for Euclidean AdS2 D-branes in H3+. This action is consistent with the D-branes' symmetries and with the H3+-Liouville relation for disc correlators. It can be used for performing free-field calculations in the H3+ model with boundaries. We explicitly perform the Coulomb-like integrals which appear in the free-field calculation of the bulk one-point function, and find agreement with previously known conformal bootstrap results.
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.
Johnson, Nicholas L.
2001-01-01
Since the Second European Conference on Space Debris in 1997, the Orbital Debris Program Office at the NASA Johnson Space Center has undertaken a major effort to update and improve the principal software tools employed to model the space debris environment and to evaluate mission risks. NASA's orbital debris engineering model, ORDEM, represents the current and near-term Earth orbital debris population from the largest spacecraft to the smallest debris in a manner which permits spacecraft engineers and experimenters to estimate the frequency and velocity with which a satellite may be struck by debris of different sizes. Using expanded databases and a new program design, ORDEM2000 provides a more accurate environment definition combined with a much broader array of output products in comparison with its predecessor, ORDEM96. Studies of the potential long-term space debris environment are now conducted with EVOLVE 4.0, which incorporates significant advances in debris characterization and breakup modeling. An adjunct to EVOLVE 4.0, GEO EVOLVE has been created to examine debris issues near the geosynchronous orbital regime. In support of NASA Safety Standard 1740.14, which establishes debris mitigation guidelines for all NASA space programs, a set of evaluation tools called the Debris Assessment Software (DAS) is specifically designed for program offices to determine whether they are in compliance with NASA debris mitigation guidelines. DAS 1.5 has recently been released with improved WINDOWS compatibility and graphics functions. DAS 2.0 will incorporate guideline changes in a forthcoming revision to NASA Safety Standard 1740.14. Whereas DAS contains a simplified model to calculate possible risks associated with satellite reentries, NASA's higher fidelity Object Reentry Survival Analysis Tool (ORSAT) has been upgraded to Version 5.0. With the growing awareness of the potential risks posed by uncontrolled satellite reentries to people and property on Earth, the
On the existence of star products on quotient spaces of linear Hamiltonian torus actions
Herbig, Hans-Christian; Iyengar, Srikanth B.; Pflaum, Markus J.
2009-01-01
Koszul complex on the moment map of an effective linear Hamiltonian torus action is acyclic. We rephrase the nonpositivity condition of Arms and Gotay (Adv Math 79(1):43–103, 1990) for linear Hamiltonian torus actions. It follows that reduced spaces of such actions admit continuous star products....
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 of intentional expert action be in line with a philosophical concept of intentional action? Answering these and related questions in a positive sense, this dissertation develops a three-step argum...
Free space in the processes of action research
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...
Map-based model of the cardiac action potential
A simple computationally efficient model which is capable of replicating the basic features of cardiac cell action potential is proposed. The model is a four-dimensional map and demonstrates good correspondence with real cardiac cells. Various regimes of cardiac activity, which can be reproduced by the proposed model, are shown. Bifurcation mechanisms of these regimes transitions are explained using phase space analysis. The dynamics of 1D and 2D lattices of coupled maps which model the behavior of electrically connected cells is discussed in the context of synchronization theory. -- Highlights: → Recent experimental-data based models are complicated for analysis and simulation. → The simplified map-based model of the cardiac cell is constructed. → The model is capable for replication of different types of cardiac activity. → The spatio-temporal dynamics of ensembles of coupled maps are investigated. → Received data are analyzed in context of biophysical processes in the myocardium.
Embedding a State Space Model Into a Markov Decision Process
Nielsen, Lars Relund; Jørgensen, Erik; Højsgaard, Søren
2011-01-01
In agriculture Markov decision processes (MDPs) with finite state and action space are often used to model sequential decision making over time. For instance, states in the process represent possible levels of traits of the animal and transition probabilities are based on biological models...
Klein, Annette M; Hauf, Petra; Aschersleben, Gisa
2006-12-01
The present study investigated differences in infant imitation after watching a televised model and a live model and addressed the issue of whether action effects influence infants' action control in both cases. In a 2x2 design, 12-month-old infants observed a live or a televised model performing a three-step action sequence, in which either the 2nd or the 3rd action step was combined with an acoustical action effect. We assumed that infants would use the observed action-effect relations for their own action control in the test phase afterwards. Even though results exhibited differences in the absolute amount of imitation between the two demonstration groups, both groups showed similar result patterns regarding the action effect manipulation: infants imitated the action step that was followed by a salient action effect more often and mostly as the first target action, emphasizing the important role of action effects in infants' action control. PMID:17138306
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.
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...
Cohomology Complex Projective Space with Actions of G5
孙淑英; 刘宗泽
2000-01-01
Let M2n be a cohomology CPn and p a prime. Set Dp(M2n) = |d >0| M2n admits a smooth Gp action such that the fixed point set of the action Gontains a codimension-2 submanifold of degree d|, DEp(M2n) = |(d; m1, m2, …, mμ)|M2n admits a Gp action of Type Ⅱ0,having multiplicities m1, m2, …, mμ at the isolated fixed points, and m1 + m2+…+ mμ = n, d is the degree of the fixed codimension-2 submanifold| In this paper, we prove that for n = 5 or 7, if D5(M2n)≠Ф, then D5(M2n) = |1|; if DE5( M2n)≠Ф, then DE5(M2n) = |(1; n, 0) |.
Effective action in general chiral superfield model
Petrov, A. Yu.
2000-01-01
The effective action in general chiral superfield model with arbitrary k\\"{a}hlerian potential $K(\\bar{\\Phi},\\Phi)$ and chiral (holomorphic) potential $W(\\Phi)$ is considered. The one-loop and two-loop contributions to k\\"{a}hlerian effective potential and two-loop (first non-zero) contribution to chiral effective potential are found for arbitrary form of functions $K(\\bar{\\Phi},\\Phi)$ and $W(\\Phi)$. It is found that despite the theory is non-renormalizable in general case two-loop contributi...
Fractional Order Modelling Using State Space Theory
Pritesh Shah
2013-06-01
Full Text Available There are various fractional order systems existing. This paper deals with the modelling of fractional order systems using an old and unique model structure i.e. state space model. The fractional order process system can be mathematically modelled by state space model. Simulation results validated that the fractional order model using state space is better as compared to other models such as first order with delay.
Effective action for a quantum scalar field in warped spaces
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.)
Critical Action Learning--Rituals and Reflective Spaces
Heneberry, Pamela; Turner, Arthur
2016-01-01
This paper is written to outline our ideas on rituals and reflective places and how this thinking has emerged through our writing, facilitation and reflections around critical action learning and critical leadership. We attempt to show the conceptual framework that underpins our vision of Critical Leadership and how out of this work we have begun…
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…
Action potential initiation in the hodgkin-huxley model.
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.
Rigidity of group actions on homogeneous spaces, III
Bader, Uri; Gorodnik, Alex; Weiss, Barak
2012-01-01
Consider homogeneous G/H and G/F, for an S-algebraic group G. A lattice {\\Gamma} acts on the left strictly conservatively. The following rigidity results are obtained: morphisms, factors and joinings defined apriori only in the measurable category are in fact algebraically constrained. Arguing in an elementary fashion we manage to classify all the measurable {\\Phi} commuting with the {\\Gamma}-action: assuming ergodicity, we find they are algebraically defined.
Frame-like actions for massless mixed-symmetry fields in Minkowski space
Skvortsov, E.D. [I.E. Tamm Department of Theoretical Physics, P.N. Lebedev Physical Institute, Leninsky prospect 53, 119991 Moscow (Russian Federation)], E-mail: skvortsov@lpi.ru
2009-02-21
A frame-like action for arbitrary mixed-symmetry bosonic massless fields in Minkowski space is constructed. The action is given in a simple form and consists of two terms for a field of any spin. The fields and gauge parameters are certain tensor-valued differential forms. The formulation is based on the unfolded form of equations for mixed-symmetry fields.
Local torus actions modeled on the standard representation
Yoshida, Takahiko
2007-01-01
We introduce the notion of a local torus action modeled on the standard representation (for simplicity, we call it a local torus action). It is a generalization of a locally standard torus action and also an underlying structure of a locally toric Lagrangian fibration. For a local torus action, we define two invariants called a characteristic pair and an Euler class of the orbit map, and prove that local torus actions are classified topologically by them. As a corollary, we obtain a topologic...
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.
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.
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.
Simplicial models for trace spaces
Raussen, Martin
Directed Algebraic Topology studies topological spaces in which certain directed paths (d-paths) - in general irreversible - are singled out. The main interest concerns the spaces of directed paths between given end points - and how those vary under variation of the end points. The original...
Action Research to Improve the Learning Space for Diagnostic Techniques.
Ariel, Ellen; Owens, Leigh
2015-12-01
The module described and evaluated here was created in response to perceived learning difficulties in diagnostic test design and interpretation for students in third-year Clinical Microbiology. Previously, the activities in lectures and laboratory classes in the module fell into the lower cognitive operations of "knowledge" and "understanding." The new approach was to exchange part of the traditional activities with elements of interactive learning, where students had the opportunity to engage in deep learning using a variety of learning styles. The effectiveness of the new curriculum was assessed by means of on-course student assessment throughout the module, a final exam, an anonymous questionnaire on student evaluation of the different activities and a focus group of volunteers. Although the new curriculum enabled a major part of the student cohort to achieve higher pass grades (p learning space for the different reagents and their interaction in diagnostic tests was proposed. The methods applied to improve and assess a curriculum refresh by involving students as partners in the process, as well as the outcomes, are discussed. Journal of Microbiology & Biology Education. PMID:26753024
Pump Component Model in SPACE Code
This technical report describes the pump component model in SPACE code. A literature survey was made on pump models in existing system codes. The models embedded in SPACE code were examined to check the confliction with intellectual proprietary rights. Design specifications, computer coding implementation, and test results are included in this report
An Evolution Model of Space Debris Environment
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.
Cosmological models in the generalized Einstein action
We have studied the evolution of the Universe in the generalized Einstein action of the form R + β R2, where R is the scalar curvature and β = const. We have found exact cosmological solutions that predict the present cosmic acceleration. These models predict an inflationary de-Sitter era occurring in the early Universe. The cosmological constant (Λ) is found to decay with the Hubble constant (H) as, Λ ∝ H4. In this scenario the cosmological constant varies quadratically with the energy density (ρ), i.e., Λ ∝ ρ2. Such a variation is found to describe a two-component cosmic fluid in the Universe. One of the components accelerated the Universe in the early era, and the other in the present era. The scale factor of the Universe varies as a ∼ tn = 1/2 in the radiation era. The cosmological constant vanishes when n = 4/3 and n =1/2. We have found that the inclusion of the term R2 mimics a cosmic matter that could substitute the ordinary matter. (author)
Fixed point action and topology in the CP3 model
We define a fixed point action in two-dimensional lattice CPN-1 models. The fixed point action is a classical perfect lattice action, which is expected to show strongly reduced cutoff effects in numerical simulations. Furthermore, the action has scale-invariant instanton solutions, which enables us to define a correct topological charge without topological defects. Using a parametrization of the fixed point action for the CP3 model in a Monte Carlo simulation, we study the topological susceptibility. copyright 1996 The American Physical Society
The Reaction RuleML Classification of the Event / Action / State Processing and Reasoning Space
Paschke, Adrian
2006-01-01
Reaction RuleML is a general, practical, compact and user-friendly XML-serialized language for the family of reaction rules. In this white paper we give a review of the history of event / action /state processing and reaction rule approaches and systems in different domains, define basic concepts and give a classification of the event, action, state processing and reasoning space as well as a discussion of relevant / related work
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 ...
L. R. Cander
2004-06-01
Full Text Available The COST 271 Action («Effects of the Upper Atmosphere on Terrestrial and Earth-space Communications » within the European ionospheric community has the objectives, embodied in the Memorandum of Understanding (MoU: to study the influence of upper atmospheric conditions on terrestrial and Earth-space communications, to develop methods and techniques to improve ionospheric models over Europe for telecommunication and navigation applications and to transfer the results to the appropriate Radiocommunication Study Groups of the International Telecommunication Union (ITU-R and other national and international organizations dealing with the modern communication systems. This introductory paper summarises briefly the background and historical context of COST 271 and outlines the main objectives, working methods and structure. It also lists the participating countries and institutions, the Management Committee (MC Meetings, Workshops and Short-term Scientific Missions. In addition, the paper discusses the dissemination of the results and the collaboration among the participating institutions and researchers, before outlining the content of the Final Report.
Inversion Copulas from Nonlinear State Space Models
Smith, Michael Stanley; Maneesoonthorn, Worapree
2016-01-01
While copulas constructed from inverting latent elliptical, or skew-elliptical, distributions are popular, they can be inadequate models of serial dependence in time series. As an alternative, we propose an approach to construct copulas from the inversion of latent nonlinear state space models. This allows for new time series copula models that have the same serial dependence structure as a state space model, yet have an arbitrary marginal distribution - something that is difficult to achieve...
Action potential initiation in the hodgkin-huxley model.
Colwell, Lucy J; Brenner, Michael P.
2009-01-01
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...
On the Cohomology of Orbit Space of Free $\\mathbb{Z}_p$-Actions on Lens Spaces
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\
One-plaquette 2 + 1 model with an arbitrary action
The one-plaquette model with a variant lattice action is investigated for the compact group G(N) in the framework of the Hamiltonian approach. The 1/N and the strong-coupling expansions in this model are constructed. The existence of the large N third order phase transition for a wide class of one-plaquette actions is proved
One-plaquette 2 + 1 model with an arbitrary action
Azakov, S.I. (AN Azerbajdzhanskoj SSR, Baku. Inst. Fiziki)
1985-01-01
The one-plaquette model with a variant lattice action is investigated for the compact group G(N) in the framework of the Hamiltonian approach. The 1/N and the strong-coupling expansions in this model are constructed. The existence of the large N third order phase transition for a wide class of one-plaquette actions is proved.
The Learning of Visually Guided Action: An Information-Space Analysis of Pole Balancing
Jacobs, David M.; Vaz, Daniela V.; Michaels, Claire F.
2012-01-01
In cart-pole balancing, one moves a cart in 1 dimension so as to balance an attached inverted pendulum. We approached perception-action and learning in this task from an ecological perspective. This entailed identifying a space of informational variables that balancers use as they perform the task and demonstrating that they improve by traversing…
Action Control of Autonomous Agents in Continuous Valued Space Using RFCN
Shirakawa, Shinichi; Nagao, Tomoharu
Researches on action control of autonomous agents and multiple agents have attracted increasing attentions in recent years. The general method using action control of agents are neural network, genetic programming and reinforcement learning. In this study, we use neural network for action control of autonomous agents. Our method determines the structure and parameter of neural network in evolution. We proposed Flexibly Connected Neural Network (FCN) previously as a method of constructing arbitrary neural networks with optimized structures and parameters to solve unknown problems. FCN was applied to action control of an autonomous agent and showed experimentally that it is effective for perceptual aliasing problems. All of the experiments of FCN, however, are in only grid space. In this paper, we propose a new method based on FCN which can decide correct action in real and continuous valued space. The proposed method which called Real valued FCN (RFCN) optimizes input-output functions of each units, parameters of the input-output functions and speed of each units. In order to examine the effectiveness, we applied the proposed method to action control of an autonomous agent to solve continuous valued maze problems.
Navigation based on symbolic space models
Baras, Karolina; Moreira, Adriano; Meneses, Filipe
2010-01-01
Existing navigation systems are very appropriate for car navigation, but lack support for convenient pedestrian navigation and cannot be used indoors due to GPS limitations. In addition, the creation and the maintenance of the required models are costly and time consuming, and are usually based on proprietary data structures. In this paper we describe a navigation system based on a human inspired symbolic space model. We argue that symbolic space models are much easier...
A fixed-point action for the lattice Schwinger model
We determine non-perturbatively a fixed-point (FP) action for fermions in the two-dimensional U(1) gauge (Schwinger) model. Our parameterization for the fermionic action has terms within a 7 x 7 square on the lattice using compact link variables. With the Wilson fermion action as starting point we determine the FP-action by iterating a block spin transformation (BST) with a blocking factor of 2 in the background of non-compact gauge field configurations sampled according to the (perfect) Gaussian measure. We simulate the model at various values of β and find excellent improvement for the studied observables. (orig.)
Space Vehicle Reliability Modeling in DIORAMA
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.
Scaling test of fermion actions in the Schwinger model
We discuss the scaling behaviour of different fermion actions in dynamical simulations of the 2-dimensional massive Schwinger model. We have chosen Wilson, hypercube, twisted mass and overlap fermion actions. As physical observables, the pion mass and the scalar condensate are computed for the above mentioned actions at a number of coupling values and fermion masses. We also discuss possibilities to simulate overlap fermions dynamically avoiding problems with low-lying eigenvalues of the overlap kernel
Scaling test of fermion actions in the Schwinger model
We discuss the scaling behaviour of different fermion actions in dynamical simulations of the 2-dimensional massive Schwinger model. We have chosen Wilson, hypercube, twisted mass and overlap fermion actions. As physical observables, the pion mass and the scalar condensate are computed for the above mentioned actions at a number of coupling values and fermion masses. We also discuss possibilities to simulate overlap fermions dynamically avoiding problems with low-lying eigenvalues of the overlap kernel. (orig.)
Modeling the value of strategic actions in the superior colliculus
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.
The Cohomology of Orbit Spaces of Certain Free Circle Group Actions
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.
Models for multimegawatt space power systems
Edenburn, M.W.
1990-06-01
This report describes models for multimegawatt, space power systems which Sandia's Advanced Power Systems Division has constructed to help evaluate space power systems for SDI's Space Power Office. Five system models and models for associated components are presented for both open (power system waste products are exhausted into space) and closed (no waste products) systems: open, burst mode, hydrogen cooled nuclear reactor -- turboalternator system; open, hydrogen-oxygen combustion turboalternator system; closed, nuclear reactor powered Brayton cycle system; closed, liquid metal Rankine cycle system; and closed, in-core, reactor therminonic system. The models estimate performance and mass for the components in each of these systems. 17 refs., 8 figs., 15 tabs.
A continuous-time neural model for sequential action
Kachergis, George; Wyatte, Dean; O'Reilly, Randall C.; de Kleijn, Roy; Hommel, Bernhard
2014-01-01
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 ...
Lag space estimation in time series modelling
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...
The fixed point action of the Schwinger model
We compute the fixed point action for the Schwinger model through an expansion in the gauge field. The calculation allows a check of the locality of the action. We test its perfection by computing the 1-loop mass gap at finite spatial volume. (orig.)
Parametric Cost Models for Space Telescopes
Stahl, H. Philip; Henrichs, Todd; Dollinger, Courtney
2010-01-01
Multivariable parametric cost models for space telescopes provide several benefits to designers and space system project managers. They identify major architectural cost drivers and allow high-level design trades. They enable cost-benefit analysis for technology development investment. And, they provide a basis for estimating total project cost. A survey of historical models found that there is no definitive space telescope cost model. In fact, published models vary greatly [1]. Thus, there is a need for parametric space telescopes cost models. An effort is underway to develop single variable [2] and multi-variable [3] parametric space telescope cost models based on the latest available data and applying rigorous analytical techniques. Specific cost estimating relationships (CERs) have been developed which show that aperture diameter is the primary cost driver for large space telescopes; technology development as a function of time reduces cost at the rate of 50% per 17 years; it costs less per square meter of collecting aperture to build a large telescope than a small telescope; and increasing mass reduces cost.
Action patterns in business process models
Smirnov, Sergey; Weidlich, Matthias; Mendling, Jan; Weske, Mathias
2009-01-01
Business process management experiences a large uptake by the industry, and process models play an important role in the analysis and improvement of processes. While an increasing number of staff becomes involved in actual modeling practice, it is crucial to assure model quality and homogeneity along with providing suitable aids for creating models. In this paper we consider the problem of offering recommendations to the user during the act of modeling. Our key contribution is a concept for d...
Transforming community access to space science models
MacNeice, Peter; Hesse, Michael; Kuznetsova, Maria; Maddox, Marlo; Rastaetter, Lutz; Berrios, David; Pulkkinen, Antti
2012-04-01
Researching and forecasting the ever changing space environment (often referred to as space weather) and its influence on humans and their activities are model-intensive disciplines. This is true because the physical processes involved are complex, but, in contrast to terrestrial weather, the supporting observations are typically sparse. Models play a vital role in establishing a physically meaningful context for interpreting limited observations, testing theory, and producing both nowcasts and forecasts. For example, with accurate forecasting of hazardous space weather conditions, spacecraft operators can place sensitive systems in safe modes, and power utilities can protect critical network components from damage caused by large currents induced in transmission lines by geomagnetic storms.
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. PMID:25267830
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
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.
Inequality Constrained State Space Models
Qian, Hang
2015-01-01
The standard Kalman filter cannot handle inequality constraints imposed on the state variables, as state truncation induces a non-linear and non-Gaussian model. We propose a Rao-Blackwellised particle filter with the optimal importance function for forward filtering and the likelihood function evaluation. The particle filter effectively enforces the state constraints when the Kalman filter violates them. We find substantial Monte Carlo variance reduction by using the optimal importance functi...
Do absolutely irreducible group actions have odd dimensional fixed point spaces?
Lauterbach, Reiner; Matthews, Paul
2010-01-01
In his volume [5] on "Symmetry Breaking for Compact Lie Groups" Mike Field quotes a private communication by Jorge Ize claiming that any bifurcation problem with absolutely irreducible group action would lead to bifurcation of steady states. The proof should come from the fact that any absolutely irreducible representation possesses an odd dimensional fixed point space. In this paper we show that there are many examples of groups which have absolutely irreducible representations but no odd di...
Verifying action semantics specifications in UML behavioral models
Planas Hortal, Elena; Cabot Sagrera, Jordi; Gómez Seoane, Cristina
2009-01-01
MDD and MDA approaches require capturing the behavior of UML models in sufficient detail so that the models can be automatically implemented/executed in the production environment. With this purpose, Action Semantics (AS) were added to the UML specification as the fundamental unit of behavior specification. Actions are the basis for defining the fine-grained behavior of operations, activity diagrams, interaction diagrams and state machines. Unfortunately, current proposals devoted to the veri...
One-plaquette (2 + 1)-model with arbitrary action
This paper investigates a one-plaquette model with arbitrary lattice action for the compact group G(N) in the framework of the Hamiltonian approach. The 1/N perturbation theory an the strong coupling expansion are considered in the model. The existence of a phase transition of the third kind in the limit of large N is proved for a large class of one-plaquette actions
One-plaquette (2 + 1)-model with arbitrary action
Azakov, S.I.
1985-08-01
This paper investigates a one-plaquette model with arbitrary lattice action for the compact group G(N) in the framework of the Hamiltonian approach. The 1/N perturbation theory an the strong coupling expansion are considered in the model. The existence of a phase transition of the third kind in the limit of large N is proved for a large class of one-plaquette actions.
A computational model of perception and action for cognitive robotics
Haazebroek, Pascal; Van Dantzig, Saskia; Hommel, Bernhard
2011-01-01
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 ...
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.
In-Space Chemical Propulsion System Model
Byers, David C.; Woodcock, Gordon; Benfield, Michael P. J.
2004-01-01
Multiple, new technologies for chemical systems are becoming available and include high temperature rockets, very light propellant tanks and structures, new bipropellant and monopropellant options, lower mass propellant control components, and zero boil off subsystems. Such technologies offer promise of increasing the performance of in-space chemical propulsion for energetic space missions. A mass model for pressure-fed, Earth and space-storable, advanced chemical propulsion systems (ACPS) was developed in support of the NASA MSFC In-Space Propulsion Program. Data from flight systems and studies defined baseline system architectures and subsystems and analyses were formulated for parametric scaling relationships for all ACPS subsystem. The paper will first provide summary descriptions of the approaches used for the systems and the subsystems and then present selected analyses to illustrate use of the model for missions with characteristics of current interest.
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.
OAST planning model for space systems technology
Sadin, S. R.
1978-01-01
The NASA Office of Aeronautics and Space Technology (OAST) planning model for space systems technology is described, and some space technology forecasts of a general nature are reported. Technology forecasts are presented as a span of technology levels; uncertainties in level of commitment to project and in required time are taken into account, with emphasis on differences resulting from high or low commitment. Forecasts are created by combining several types of data, including information on past technology trends, the trends of past predictions, the rate of advancement predicted by experts in the field, and technology forecasts already published.
Multimedia Mapping using Continuous State Space Models
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....
Institutional Model of Decentralization in Action
Azis, Iwan J.
2011-01-01
Applying the Institutional Model of Decentralization, the paper argues that the presumption that local democracy will impose accountability pressure on elected officials does not always hold. Even in a democratic system like in Indonesia, decentralization policy is welfare-enhancing only for the developed regions, not for all, exacerbating interregional welfare disparity. This "captured democracy" is largely due to the presence of "negative local capture". Where welfare has not improved, limi...
The communicative action and information: a learning to learn transdisciplinary model
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.
Edgeworth streaming model for redshift space distortions
Uhlemann, Cora; Kopp, Michael; Haugg, Thomas
2015-09-01
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 radius, we extend CLPT to the coarse-grained dust model and consider two different smoothing approaches operating in Eulerian and Lagrangian space, respectively. The coarse graining in Eulerian space features modified fluid dynamics different from dust while the coarse graining in Lagrangian space is performed in the initial conditions with subsequent single-streaming dust dynamics, implemented by smoothing the initial power spectrum in the spirit of the truncated Zel'dovich approximation. Finally, we compare the predictions of the different coarse-grained models for the streaming model ingredients to N -body measurements and comment on the proper choice of both the tracer distribution function and the smoothing scale. Since the perturbative methods we considered are not yet accurate enough on small scales, the GSM is sufficient when applied to perturbation theory.
Mouse infection models for space flight immunology
Chapes, Stephen Keith; Ganta, Roman Reddy; Chapers, S. K. (Principal Investigator)
2005-01-01
Several immunological processes can be affected by space flight. However, there is little evidence to suggest that flight-induced immunological deficits lead to illness. Therefore, one of our goals has been to define models to examine host resistance during space flight. Our working hypothesis is that space flight crews will come from a heterogeneous population; the immune response gene make-up will be quite varied. It is unknown how much the immune response gene variation contributes to the potential threat from infectious organisms, allergic responses or other long term health problems (e.g. cancer). This article details recent efforts of the Kansas State University gravitational immunology group to assess how population heterogeneity impacts host health, either in laboratory experimental situations and/or using the skeletal unloading model of space-flight stress. This paper details our use of several mouse strains with several different genotypes. In particular, mice with varying MHCII allotypes and mice on the C57BL background with different genetic defects have been particularly useful tools with which to study infections by Staphylococcus aureus, Salmonella typhimurium, Pasteurella pneumotropica and Ehrlichia chaffeensis. We propose that some of these experimental challenge models will be useful to assess the effects of space flight on host resistance to infection.
Gauge invariant actions for string models
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
Gauge invariant actions for string models
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.
Heat kernel expansion and induced action for matrix models
In this proceeding note, I review some recent results concerning the quantum effective action of certain matrix models, i.e. the supersymmetric IKKT model, in the context of emergent gravity. The absence of pathological UV/IR mixing is discussed, as well as dynamical SUSY breaking and some relations with string theory and supergravity.
Cosmological Models with Fractional Derivatives and Fractional Action Functional
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.
State Space Model for Aggregated Longitudial Data
Brabec, Marek; Konár, Ondřej; Malý, Marek; Pelikán, Emil; Vondráček, Jiří
New York: State University, 2007. s. 46-46. [ISF'2007. International Symposium on Forecasting /27./. 24.06.2007-27.06.2007, New York] R&D Projects: GA AV ČR 1ET400300513 Institutional research plan: CEZ:AV0Z10300504 Keywords : Kalman filter * state space model * natural gas
Cost Modeling for Space Optical Telescope Assemblies
Stahl, H. Philip; Henrichs, Todd; Luedtke, Alexander; West, Miranda
2011-01-01
Parametric cost models are used to plan missions, compare concepts and justify technology investments. This paper reviews an on-going effort to develop cost modes for space telescopes. This paper summarizes the methodology used to develop cost models and documents how changes to the database have changed previously published preliminary cost models. While the cost models are evolving, the previously published findings remain valid: it costs less per square meter of collecting aperture to build a large telescope than a small telescope; technology development as a function of time reduces cost; and lower areal density telescopes cost more than more massive telescopes.
Multivariable Wind Modeling in State Space
Sichani, Mahdi Teimouri; Pedersen, B. J.
2011-01-01
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...... for the vector turbulence process incorporating its phase spectrum in one stage, and its results are compared with a conventional ARMA modeling method....
Numerical modelling of elastic space tethers
Kristiansen, Kristian Uldall; Palmer, P. L.; Roberts, R. M.
2012-01-01
, 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....... It is also shown that on the slow manifold the dynamics of the satellites are well-approximated by the finite dimensional slack-spring model....
Brown, Ronald; Higgins, Philip J.
2002-01-01
The main result is that the fundamental groupoid of the orbit space of a discontinuous action of a discrete group on a Hausdorff space which admits a universal cover is the orbit groupoid of the fundamental groupoid of the space. We also describe work of Higgins and of Taylor which makes this result usable for calculations. As an example, we compute the fundamental group of the symmetric square of a space. The main result, which is related to work of Armstrong, is due to Brown and Higgins in ...
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.
Expanded Parts Model for Human Attribute and Action Recognition in Still Images
Sharma, Gaurav; Jurie, Frédéric; Schmid, Cordelia
2013-01-01
We propose a new model for recognizing human attributes (e.g. wearing a suit, sitting, short hair) and actions (e.g. running, riding a horse) in still images. The proposed model relies on a collection of part templates which are learnt discriminatively to explain specific scale-space locations in the images (in human centric coordinates). It avoids the limitations of highly structured models, which consist of a few (i.e. a mixture of) 'average' templates. To learn our model, we propose an alg...
Do absolutely irreducible group actions have odd dimensional fixed point spaces?
Lauterbach, Reiner
2010-01-01
In his volume [5] on "Symmetry Breaking for Compact Lie Groups" Mike Field quotes a private communication by Jorge Ize claiming that any bifurcation problem with absolutely irreducible group action would lead to bifurcation of steady states. The proof should come from the fact that any absolutely irreducible representation possesses an odd dimensional fixed point space. In this paper we show that there are many examples of groups which have absolutely irreducible representations but no odd dimensional fixed point space. This observation may be relevant also for some degree theoretic considerations concerning equivariant bifurcation. Moreover we show that our examples give rise to some interesting Hamiltonian dynamics and we show that despite some complications we can go a long way towards doing explicit computations and providing complete proofs. For some of the invariant theory needed we will depend on some computer aided computations. The work presented here greatly benefited from the computer algebra progr...
The Perception-Action Model: Counting Computational Mechanisms
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...
A statistical model of possible future human actions
A critical review has been carried out of models of possible future human actions during the long-term post-closure period of a radioactive waste repository. Various Markov models have been considered as alternatives to the more conventional Poisson model, and the problems of parameterisation have been addressed. Where the Poisson model unduly exaggerates the intrusion risk, some form of Markov model may have to be introduced. This situation may well arise for shallow repositories, but it is thought less likely for deep repositories. Consideration of state transition within a Markov model highlights the value of increasing the availability of site information. (author)
Animated pose templates for modeling and detecting human actions.
Yao, Benjamin Z; Nie, Bruce X; Liu, Zicheng; Zhu, Song-Chun
2014-03-01
This paper presents animated pose templates (APTs) for detecting short-term, long-term, and contextual actions from cluttered scenes in videos. Each pose template consists of two components: 1) a shape template with deformable parts represented in an And-node whose appearances are represented by the Histogram of Oriented Gradient (HOG) features, and 2) a motion template specifying the motion of the parts by the Histogram of Optical-Flows (HOF) features. A shape template may have more than one motion template represented by an Or-node. Therefore, each action is defined as a mixture (Or-node) of pose templates in an And-Or tree structure. While this pose template is suitable for detecting short-term action snippets in two to five frames, we extend it in two ways: 1) For long-term actions, we animate the pose templates by adding temporal constraints in a Hidden Markov Model (HMM), and 2) for contextual actions, we treat contextual objects as additional parts of the pose templates and add constraints that encode spatial correlations between parts. To train the model, we manually annotate part locations on several keyframes of each video and cluster them into pose templates using EM. This leaves the unknown parameters for our learning algorithm in two groups: 1) latent variables for the unannotated frames including pose-IDs and part locations, 2) model parameters shared by all training samples such as weights for HOG and HOF features, canonical part locations of each pose, coefficients penalizing pose-transition and part-deformation. To learn these parameters, we introduce a semi-supervised structural SVM algorithm that iterates between two steps: 1) learning (updating) model parameters using labeled data by solving a structural SVM optimization, and 2) imputing missing variables (i.e., detecting actions on unlabeled frames) with parameters learned from the previous step and progressively accepting high-score frames as newly labeled examples. This algorithm belongs to a
Generation of action plans for two mobile robots designed to operate in a space full of obstacles
The paper describes a simulation study conducted on an action plan generator for two mobile robots designed to operate in a space full of obstacles. This plan generator should be able to convert an objective specified by a user into a series of elementary actions, thus reflecting the 'intelligent' behaviour of robots. These actions involve finding the optimum path, avoiding obstacles (for each robot), and solving navigational problems, namely detecting robot-robot collisions and critical situations. A model representing the environment in which the path has to be found is described. The course obtained is optimized by applying a variant of the 'branch and bound' A* algorithm, assigning to each section of the path a cost which is, in fact, the minimum distance to be covered. The navigation strategy is based on the analysis of the paths found and the application of the traffic rules. In order to do this, it was necessary to introduce a classification based on the risks of collision in areas referred to as 'static interference zones'. (author). 8 refs, 7 figs
Adaptive numerical algorithms in space weather modeling
Tóth, Gábor; van der Holst, Bart; Sokolov, Igor V.; De Zeeuw, Darren L.; Gombosi, Tamas I.; Fang, Fang; Manchester, Ward B.; Meng, Xing; Najib, Dalal; Powell, Kenneth G.; Stout, Quentin F.; Glocer, Alex; Ma, Ying-Juan; Opher, Merav
2012-02-01
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 relevant physics in different domains. A multi-physics system can be modeled by a software framework comprising 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 Solarwind Roe-type Upwind Scheme (BATS-R-US) code that can solve various forms of the magnetohydrodynamic (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
Adaptive numerical algorithms in space weather modeling
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 relevant physics in different domains. A multi-physics system can be modeled by a software framework comprising 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 Solarwind Roe-type Upwind Scheme (BATS-R-US) code that can solve various forms of the magnetohydrodynamic (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
Fixed point action for the massless lattice Schwinger model
We determine non-perturbatively the fixed-point action for fermions in the two-dimensional U(1) gauge (Schwinger) model. This is done by iterating a block spin transformation in the background of non-compact gauge field configurations sampled according to the (perfect) Gaussian measure. The resulting action has 123 independent couplings, is bilinear in the Grassmann fields, gauge invariant by the compact gauge transporters considered, and localized within a 7 x 7 lattice centered around one of the fermions. We then simulate the model at various values of β and compare with results obtained with the Wilson fermion action. We find excellent improvement for the observables studied (propagators and masses). (orig.)
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.
Study on Strand Space Model Theory
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.
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.
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 ...
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
Singlet vector models on lens spaces
We present exact computations of partition functions of singlet vector models (infinite level Chern-Simons-matter theories) on lens spaces L(p,1). We identify light topological configurations and their spectra, and we comment on the relevance of our results in studying both the UV completions of Vasiliev’s higher-spin theories and the dS/CFT correspondence in the large N limit
Jointly structuring triadic spaces of meaning and action: book sharing from 3 months on.
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.
Effective actions near singularities: the STU-model
We derive the low energy effective action of the STU-model in four and five dimensions near the line T=U where SU(2) gauge symmetry enhancement occurs. By 'integrating in' the light W± bosons together with their superpartners, the quantum corrected effective action becomes non-singular at T=U and manifestly SU(2) invariant. The four-dimensional theory is found to be consistent with modular invariance and the five-dimensional decompactification limit. (Abstract Copyright [2003], Wiley Periodicals, Inc.)
String states, loops and effective actions in noncommutative field theory and matrix models
Steinacker, Harold C
2016-01-01
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
Steinacker, Harold C.
2016-09-01
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.
Einstein spaces modeling nonminimal modified gravity
Elizalde, Emilio; Vacaru, Sergiu I.
2015-06-01
Off-diagonal vacuum and nonvacuum configurations in the Einstein gravity can mimic physical effects of modified gravitational theories of f( R, T, R μν T μν ) type. To prove this statement, exact and approximate solutions are constructed in the paper, which encode certain models of covariant Hořava-type gravity with dynamical Lorentz symmetry breaking. The corresponding FLRW cosmological dynamics with possible nonholonomic deformations and the reconstruction procedure of certain actions closely related with the standard ΛCDM universe are studied. Off-diagonal generalizations of de Sitter universes are constructed which are generated through nonlinear gravitational polarization of fundamental physical constants and which model interactions with nonconstant exotic fluids and effective matter. The problem of possible matter instability for such off-diagonal deformations in (modified) gravity theories is briefly discussed.
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...
Mathematical models for space shuttle ground systems
Tory, E. G.
1985-01-01
Math models are a series of algorithms, comprised of algebraic equations and Boolean Logic. At Kennedy Space Center, math models for the Space Shuttle Systems are performed utilizing the Honeywell 66/80 digital computers, Modcomp II/45 Minicomputers and special purpose hardware simulators (MicroComputers). The Shuttle Ground Operations Simulator operating system provides the language formats, subroutines, queueing schemes, execution modes and support software to write, maintain and execute the models. The ground systems presented consist primarily of the Liquid Oxygen and Liquid Hydrogen Cryogenic Propellant Systems, as well as liquid oxygen External Tank Gaseous Oxygen Vent Hood/Arm and the Vehicle Assembly Building (VAB) High Bay Cells. The purpose of math modeling is to simulate the ground hardware systems and to provide an environment for testing in a benign mode. This capability allows the engineers to check out application software for loading and launching the vehicle, and to verify the Checkout, Control, & Monitor Subsystem within the Launch Processing System. It is also used to train operators and to predict system response and status in various configurations (normal operations, emergency and contingent operations), including untried configurations or those too dangerous to try under real conditions, i.e., failure modes.
Spatial and frequency domain ring source models for the single muscle fiber action potential
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...... parallel to the fibre axis. Consequently, they cannot easily evaluate the potential at the boundary nodes of a boundary-element electrode model. The Fourier-domain models employ axial-symmetric ring source models, and thereby provide higher accuracy that the line source model, where the source is lumped...... examples including anisotropy show that the spatial models require extreme care in the integration procedure owing to the singularity in the weighting functions. With adequate sampling, the spatial models can evaluate extracellular potentials with high accuracy....
Using modeling to develop and evaluate a corrective action system
At a former trucking facility in EPA Region 4, a corrective action system was installed to remediate groundwater and soil contaminated with gasoline and fuel oil products released from several underground storage tanks (USTs). Groundwater modeling was used to develop the corrective action plan and later used with soil vapor modeling to evaluate the systems effectiveness. Groundwater modeling was used to determine the effects of a groundwater recovery system on the water table at the site. Information gathered during the assessment phase was used to develop a three dimensional depiction of the subsurface at the site. Different groundwater recovery schemes were then modeled to determine the most effective method for recovering contaminated groundwater. Based on the modeling and calculations, a corrective action system combining soil vapor extraction (SVE) and groundwater recovery was designed. The system included seven recovery wells, to extract both soil vapor and groundwater, and a groundwater treatment system. Operation and maintenance of the system included monthly system sampling and inspections and quarterly groundwater sampling. After one year of operation the effectiveness of the system was evaluated. A subsurface soil gas model was used to evaluate the effects of the SVE system on the site contamination as well as its effects on the water table and groundwater recovery operations. Groundwater modeling was used in evaluating the effectiveness of the groundwater recovery system. Plume migration and capture were modeled to insure that the groundwater recovery system at the site was effectively capturing the contaminant plume. The two models were then combined to determine the effects of the two systems, acting together, on the remediation process
Model-based vision for space applications
Chaconas, Karen; Nashman, Marilyn; Lumia, Ronald
1992-01-01
This paper describes a method for tracking moving image features by combining spatial and temporal edge information with model based feature information. The algorithm updates the two-dimensional position of object features by correlating predicted model features with current image data. The results of the correlation process are used to compute an updated model. The algorithm makes use of a high temporal sampling rate with respect to spatial changes of the image features and operates in a real-time multiprocessing environment. Preliminary results demonstrate successful tracking for image feature velocities between 1.1 and 4.5 pixels every image frame. This work has applications for docking, assembly, retrieval of floating objects and a host of other space-related tasks.
Content Modelling for Human Action Detection via Multidimensional Approach
Lili N. A.
2009-03-01
Full Text Available Video content analysis is an active research domain due to the availability andthe increment of audiovisual data in the digital format. There is a need toautomatically extracting video content for efficient access, understanding,browsing and retrieval of videos. To obtain the information that is of interest andto provide better entertainment, tools are needed to help users extract relevantcontent and to effectively navigate through the large amount of available videoinformation. Existing methods do not seem to attempt to model and estimate thesemantic content of the video. Detecting and interpreting human presence,actions and activities is one of the most valuable functions in this proposedframework. The general objectives of this research are to analyze and processthe audio-video streams to a robust audiovisual action recognition system byintegrating, structuring and accessing multimodal information viamultidimensional retrieval and extraction model. The proposed techniquecharacterizes the action scenes by integrating cues obtained from both the audioand video tracks. Information is combined based on visual features (motion,edge, and visual characteristics of objects, audio features and video forrecognizing action. This model uses HMM and GMM to provide a framework forfusing these features and to represent the multidimensional structure of theframework. The action-related visual cues are obtained by computing the spatiotemporaldynamic activity from the video shots and by abstracting specific visualevents. Simultaneously, the audio features are analyzed by locating and computeseveral sound effects of action events that embedded in the video. Finally, theseaudio and visual cues are combined to identify the action scenes. Compared withusing single source of either visual or audio track alone, such combined audiovisualinformation provides more reliable performance and allows us tounderstand the story content of movies in more detail. To compare the
Merging linear discriminant analysis with Bag of Words model for human action recognition
Iosifidis, Alexandros; Tefas, Anastasios; Pitas, Ioannis
2016-01-01
In this paper we propose a novel method for human action recognition, that unifies discriminative Bag of Words (BoW)-based video representation and discriminant subspace learning. An iterative optimization scheme is proposed for sequential discriminant BoWs-based action representation and codebook adaptation based on action discrimination in a reduced dimensionality feature space where action classes are better discriminated. Experiments on four publicly available action recognition data sets...
Model reduction results for flexible space structures
Williams, Trevor; Mostarshedi, Masoud
1993-01-01
This paper describes the novel subsystem balancing technique for obtaining reduced-order models of flexible structures, and investigates its properties fully. This method can be regarded as a combination of the best features of modal truncation (efficiency) and internal balancing (accuracy); it is particularly well suited to the typical practical case of structures which possess clusters of close modes. Numerical results are then presented demonstrating the results obtained by applying subsystem balancing to the Air Force Phillips Laboratory ASTREX testbed, the Jet Propulsion Laboratory antenna facility, and the NASA Marshall Space Flight Center ACES structure.
STS-35 Mission Manager Actions Room at the Marshall Space Flight Center Spacelab Payload Operations
1990-01-01
The primary objective of the STS-35 mission was round the clock observation of the celestial sphere in ultraviolet and X-Ray astronomy with the Astro-1 observatory which consisted of four telescopes: the Hopkins Ultraviolet Telescope (HUT); the Wisconsin Ultraviolet Photo-Polarimeter Experiment (WUPPE); the Ultraviolet Imaging Telescope (UIT); and the Broad Band X-Ray Telescope (BBXRT). The Huntsville Operations Support Center (HOSC) Spacelab Payload Operations Control Center (SL POCC) at the Marshall Space Flight Center (MSFC) was the air/ground communication channel used between the astronauts and ground control teams during the Spacelab missions. Teams of controllers and researchers directed on-orbit science operations, sent commands to the spacecraft, received data from experiments aboard the Space Shuttle, adjusted mission schedules to take advantage of unexpected science opportunities or unexpected results, and worked with crew members to resolve problems with their experiments. Due to loss of data used for pointing and operating the ultraviolet telescopes, MSFC ground teams were forced to aim the telescopes with fine tuning by the flight crew. This photo captures the activities at the Mission Manager Actions Room during the mission.
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
Space weather: Modeling and forecasting ionospheric
Full text: Space weather is the set of phenomena and interactions that take place in the interplanetary medium. It is regulated primarily by the activity originating in the Sun and affects both the artificial satellites that are outside of the protective cover of the Earth's atmosphere as the rest of the planets in the solar system. Among the phenomena that are of great relevance and impact on Earth are the auroras and geomagnetic storms , these are a direct result of irregularities in the flow of the solar wind and the interplanetary magnetic field . Given the high complexity of the physical phenomena involved (magnetic reconnection , particle inlet and ionizing radiation to the atmosphere) one of the great scientific challenges today is to forecast the state of plasmatic means either the interplanetary medium , the magnetosphere and ionosphere , for their importance to the development of various human activities such as radio , global positioning , navigation, etc. . It briefly address some of the international ionospheric modeling methods and contributions and participation that currently has the space group of the Institute of Geophysics Geophysics and Astronomy (IGA) in these activities of modeling and forecasting ionospheric. (author)
Accident sequence modeling: human actions, system response, intelligent decision support
In Probabilistic Safety Assessment (PSA) of large technological systems, accident sequence modeling represents the synthesis of expert judgement, system modeling, and operational evidence. This book contains the papers that were presented at a two-day Seminar that was held in Munich in August 1987. The aim of this Seminar was to provide a forum for in-depth discussion in a workshop atmosphere of the key elements in the modeling process, such as operator actions and system response, and to assess the possibilities of using such models to design operator decision support systems in the form of expert systems or interactive man computer structures. While this evaluation of the state of the art was done in the context of nuclear power reactor safety, most of the models and ideas advanced by the participants have wide applicability and can be used in safety assessments and reliability enhancement programs for other fields, for example the chemical process and aerospace industries. (author)
Reputation and competition in a hidden action model.
Alessandro Fedele
Full Text Available The economics models of reputation and quality in markets can be classified in three categories. (i Pure hidden action, where only one type of seller is present who can provide goods of different quality. (ii Pure hidden information, where sellers of different types have no control over product quality. (iii Mixed frameworks, which include both hidden action and hidden information. In this paper we develop a pure hidden action model of reputation and Bertrand competition, where consumers and firms interact repeatedly in a market with free entry. The price of the good produced by the firms is contractible, whilst the quality is noncontractible, hence it is promised by the firms when a contract is signed. Consumers infer future quality from all available information, i.e., both from what they know about past quality and from current prices. According to early contributions, competition should make reputation unable to induce the production of high-quality goods. We provide a simple solution to this problem by showing that high quality levels are sustained as an outcome of a stationary symmetric equilibrium.
Reputation and competition in a hidden action model.
Fedele, Alessandro; Tedeschi, Piero
2014-01-01
The economics models of reputation and quality in markets can be classified in three categories. (i) Pure hidden action, where only one type of seller is present who can provide goods of different quality. (ii) Pure hidden information, where sellers of different types have no control over product quality. (iii) Mixed frameworks, which include both hidden action and hidden information. In this paper we develop a pure hidden action model of reputation and Bertrand competition, where consumers and firms interact repeatedly in a market with free entry. The price of the good produced by the firms is contractible, whilst the quality is noncontractible, hence it is promised by the firms when a contract is signed. Consumers infer future quality from all available information, i.e., both from what they know about past quality and from current prices. According to early contributions, competition should make reputation unable to induce the production of high-quality goods. We provide a simple solution to this problem by showing that high quality levels are sustained as an outcome of a stationary symmetric equilibrium. PMID:25329387
COST Action FP1005 ``Fibre suspension flow modelling''
Marchioli, Cristian
2013-11-01
Fibre suspensions are extremely complex solid-liquid systems since their components (fibres, flocs, air bubbles and additives) interact mutually in a complex way. The dynamics of fibre suspensions are crucial in many real-life applications, such as pulp and paper production. Current understanding of suspension flow dynamics remains poor and incomplete, resulting in conservative design of industrial equipments, low energy efficiency and equipment oversizing. In this paper, the most recent advancements in modelling and experimentation of fibre suspensions dynamics are presented. These advancements have been obtained in the framework of Action FP1005, funded by the COST Programme (European Cooperation in Science and Technology) to coordinate nationally-funded research on a European level. The Action aims at developing and validating numerical models for prediction of fibre suspensions as well as measurement techniques. The Action offers a forum to solve test cases and to compare simulated results to experiments, resulting in more reliable simulation tools to industry. Successfull introduction of such tool into industrial practice is crucial to innovate and increase competitivity of papermaking industry.
Numerical Modeling of Ocular Dysfunction in Space
Nelson, Emily S.; Mulugeta, Lealem; Vera, J.; Myers, J. G.; Raykin, J.; Feola, A. J.; Gleason, R.; Samuels, B.; Ethier, C. R.
2014-01-01
Upon introduction to microgravity, the near-loss of hydrostatic pressure causes a marked cephalic (headward) shift of fluid in an astronaut's body. The fluid shift, along with other factors of spaceflight, induces a cascade of interdependent physiological responses which occur at varying time scales. Long-duration missions carry an increased risk for the development of the Visual Impairment and Intracranial Pressure (VIIP) syndrome, a spectrum of ophthalmic changes including posterior globe flattening, choroidal folds, distension of the optic nerve sheath, kinking of the optic nerve and potentially permanent degradation of visual function. In the cases of VIIP found to date, the initial onset of symptoms occurred after several weeks to several months of spaceflight, by which time the gross bodily fluid distribution is well established. We are developing a suite of numerical models to simulate the effects of fluid shift on the cardiovascular, central nervous and ocular systems. These models calculate the modified mean volumes, flow rates and pressures that are characteristic of the altered quasi-homeostatic state in microgravity, including intracranial and intraocular pressures. The results of the lumped models provide initial and boundary data to a 3D finite element biomechanics simulation of the globe, optic nerve head and retrobulbar subarachnoid space. The integrated set of models will be used to investigate the evolution of the biomechanical stress state in the ocular tissues due to long-term exposure to microgravity.
Space Power System Modeling with EBAL
Pratt and Whitney Rocket dyne's Engine Balance (EBAL) thermal/fluid system code has been expanded to model nuclear power closed Brayton cycle (CBC) power conversion systems. EBAL was originally developed to perform design analysis of hypersonic vehicle propellant and thermal management systems analysis. Later, it was adapted to rocket engine cycles. The new version of EBAL includes detailed, physics-based models of all key CBC system components. Some component examples are turbo-alternators, heat exchangers, heat pipe radiators, and liquid metal pumps. A liquid metal cooled reactor is included and a gas cooled reactor model is in work. Both thermodynamic and structural analyses are performed for each component. EBAL performs steady-state design analysis with optimization as well as off-design performance analysis. Design optimization is performed both at the component level by the component models and on the system level with a global optimizer. The user has the option to manually drive the optimization process or run parametric analysis to better understand system trade-off. Although recent EBAL developments have focused on a CBC conversion system, the code is easily extendible to other power conversion cycles. This new, more powerful version of EBAL allows for rapid design analysis and optimization of space power systems. A notional example of EBAL's capabilities is included. (authors)
Propagation of signals in spaces with affine connections and metrics as models of space-time
Manoff, Sawa
2003-01-01
The propagation of signals in space-time is considered on the basis of the notion of null (isotropic) vector field in spaces with affine connections and metrics as models of space or of space-time. The Doppler effect is generalized for these types of spaces. The notions of aberration, standard (longitudinal) Doppler effect, and transversal Doppler effect are considered. On their grounds, the Hubble effect appears as Doppler effect with explicit forms of the centrifugal (centripetal) and Corio...
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.
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
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.
Integrability of geodesics and action-angle variables in Sasaki-Einstein space $T^{1,1}$
Visinescu, Mihai
2016-01-01
We briefly describe the construction of St\\"akel-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 these spaces. We present the set of functionally independent integrals of motion for the homogeneous Sasaki-Einstein space $T^{1,1}$. We discuss the integrability of geodesics and construct explicitly the action-angle variables.
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. PMID:26651988
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.
Testing fermion actions. Scaling in the Schwinger model
We test the scaling behaviour of Wilson, hypercube, maximally twisted mass and overlap fermion actions in dynamical simulations of the 2-dimensional massive Schwinger model. We also present possibilities to simulate overlap fermions dynamically by replacing the exact overlap operator by an approximate version. This approximation is used either as only the guidance Hamiltonian, keeping the exact overlap operator as the accept/reject Hamiltonian or for both, the guidance and accept/reject Hamiltonian in the Hybrid Monte Carlo algorithm. In the latter case we test whether the approximation error can be corrected for by computing the determinant ratio of the exact and the approximate overlap operators stochastically. (orig.)
The effective action approach applied to nuclear chiral sigma model
The nuclear chiral sigma model of nuclear matter is considered by means of the Cornwall-Jackiw-tomboulis (CTJ) effective action. The method provides a very general framework for investigating many important problems: chiral symmetry in nuclear medium, energy density of nuclear ground state, nuclear Schwinger-Dyson (SD) equations, etc. It is shown that the SD equations for sigma-omega mixing are actually not present in this formalism. For numerical computation purposes the Hartree-Fock (HF) approximation for ground state energy density is also presented. (author). 26 refs
The Diversity of Enterprise Modeling – a Taxonomy for Enterprise Modeling Actions
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.
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.
Spectral action for Bianchi type-IX cosmological models
Fan, Wentao; Fathizadeh, Farzad; Marcolli, Matilde
2015-10-01
A rationality result previously proved for Robertson-Walker metrics is extended to a homogeneous anisotropic cosmological model, namely the Bianchi type-IX minisuperspace. It is shown that the Seeley-de Witt coefficients appearing in the expansion of the spectral action for the Bianchi type-IX geometry are expressed in terms of polynomials with rational coefficients in the cosmic evolution factors w 1( t) , w 2( t) , w 3( t) , and their higher derivates with respect to time. We begin with the computation of the Dirac operator of this geometry and calculate the coefficients a 0 ,a 2 ,a 4 of the spectral action by using heat kernel methods and parametric pseudodifferential calculus. An efficient method is devised for computing the Seeley-de Witt coefficients of a geometry by making use of Wodzicki's noncommutative residue, and it is confirmed that the method checks out for the cosmological model studied in this article. The advantages of the new method are discussed, which combined with symmetries of the Bianchi type-IX metric, yield an elegant proof of the rationality result.
Spectral Action for Bianchi Type-IX Cosmological Models
Fan, Wentao; Marcolli, Matilde
2015-01-01
A rationality result previously proved for Robertson-Walker metrics is extended to a homogeneous anisotropic cosmological model, namely the Bianchi type-IX minisuperspace. It is shown that the Seeley-de Witt coefficients appearing in the expansion of the spectral action for the Bianchi type-IX geometry are expressed in terms of polynomials with rational coefficients in the cosmic evolution factors $w_1(t), w_2(t), w_3(t),$ and their higher derivates with respect to time. We begin with the computation of the Dirac operator of this geometry and calculate the coefficients $a_0, a_2, a_4$ of the spectral action by using heat kernel methods and parametric pseudodifferential calculus. An efficient method is devised for computing the Seeley-de Witt coefficients of a geometry by making use of Wodzicki's noncommutative residue, and it is confirmed that the method checks out for the cosmological model studied in this article. The advantages of the new method are discussed, which combined with symmetries of the Bianchi ...
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 ...
Evaluating model of frozen soil environment change under engineering actions
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.
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.
Weyl Action of Two-Column Mixed-Symmetry Field and Its Factorization Around (A)dS Space
Joung, Euihun
2016-01-01
We investigate the four-derivative free Weyl action for two-column mixed-symmetry field that makes use of maximal gauge symmetries. In flat space, the action can be uniquely determined from gauge and Weyl (trace shift) symmetry requirements. We show that there is a smooth and unique deformation of the flat action to (A)dS which keeps the same amount of gauge symmetries. This action admits a factorization into two distinct two-derivative actions having gauge parameters of different Young diagrams. Hence, this factorization pattern naturally extends that of the Weyl actions of symmetric higher spin fields to mixed-symmetry cases. The mass-deformation for these actions can be realized preserving one of the gauge symmetries. Although generically non-unitary, in special dimensions, unitarity is achieved selecting different mass deformations for dS and AdS. We consider particular examples of our construction such as New Massive Gravity in three dimensions, linearized bigravity in four dimensions and their arbitrary...
Space Logistics Modeling and Simulation Analysis using SpaceNet: Four Application Cases
Grogan, Paul Thomas; Yue, Howard K.; de Weck, Olivier L.
2011-01-01
The future of space exploration will not be limited to sortie-style missions to single destinations. Even in present exploration taking place at the International Space Station in low-Earth orbit, logistics is complicated by flights arriving from five launch sites on Earth. The future challenges of space logistics given complex campaigns of interconnected missions in deep space will require innovative tools to aid planning and conceptual design. This paper presents a modeling framework to eva...
Spinors on a curved noncommutative space: coupling to torsion and the Gross-Neveu model
Burić, Maja; Madore, John; Nenadović, Luka
2015-09-01
We analyse the Dirac action on the truncated Heisenberg algebra and in particular, the nonminimal couplings to the background gravitational field. By projection to the Heisenberg algebra we obtain a renormalisable model: the noncommutative extension of the Gross-Neveu model. This result indicates that, as on the commutative curved backgrounds, nonminimal couplings with torsion and curvature are necessary (and sufficient) for renormalisability of scalar and spinor theories on the curved noncommutative spaces.
Enhanced surrogate models for statistical design exploiting space mapping technology
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...
Dynamic simulation of hydrodynamic model of drum level wave action and sloshing
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.
Optimization using surrogate models - by the space mapping technique
Søndergaard, Jacob
2003-01-01
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...... 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......Surrogate modelling and optimization techniques are intended for engineering design in the case where an expensive physical model is involved. This thesis provides a literature overview of the field of surrogate modelling and optimization. The space mapping technique is one such method...
On Stable Equilibria in Discrete-Space Social Interaction Models
AKAMATSU Takashi; Fujishima, Shota; Takayama, Yuki
2014-01-01
We investigate the differences and connections between discrete-space and continuous-space social interaction models. Although our class of continuous-space model has a unique equilibrium, we find that discretized models can have multiple equilibria for any degree of discretization, which necessitates a stability analysis of equilibria. We present a general framework for characterizations of equilibria and their stability under a broad class of evolutionary dynamics by using the properties of...
Clausen, Christian
2004-01-01
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...... 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 Novel Reinforcement Learning Architecture for Continuous State and Action Spaces
Víctor Uc-Cetina
2013-01-01
We introduce a reinforcement learning architecture designed for problems with an infinite number of states, where each state can be seen as a vector of real numbers and with a finite number of actions, where each action requires a vector of real numbers as parameters. The main objective of this architecture is to distribute in two actors the work required to learn the final policy. One actor decides what action must be performed; meanwhile, a second actor determines the right parameters for t...
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.
Extracting Space Weather Information from Research Models: Opportunities and Challenges
Hesse, Michael
2010-01-01
In addition to supporting space research in the international community, the Community Coordinated Modeling Center (CCMC) has as its second objective to apply the power of modern research models toward space weather specification and forecasting. Motivated by the objectives to test models and to ease the transition of research models to space weather forecasting organizations, the CCMC has developed a number of real-time modeling systems, as well as a large number of modeling and data products for space weather forecasting support. Over time, these activities have produced tailored products for partners, as well as tools, which address the space weather needs of NASA's robotic mission community. All tools are accessible via a configurable, flexible interface. During this process, CCMC has accumulated substantial experience in understanding model performance, as well as in the design and execution of realtime systems. This presentation will focus on lessons learned and it will suggest low hanging fruit for transition to operations at partner agencies.
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
2006-01-01
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 power of (-40) times the energy of the crystalline structure of vacuum space inside the present Universe volume.
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
Portable space mapping for efficient statistical modeling of passive components
Zhang, L; Aaen, PH; Wood, J.
2012-01-01
In this paper, a portable space-mapping technique is presented for efficient statistical modeling of passive components. The proposed technique utilizes the cost-effective model composition of a statistical space mapping, while introducing the portable mapping concept for flexible model development for passive modeling. The portable mapping is a single-development-multiple-use versatile wrapper, such that after development it can be conveniently combined with any nominal model to form a set o...
Commentary : working across distant spaces : connecting participatory action research and teaching.
Pain, R.
2009-01-01
This commentary reflects on the key themes and goals of this symposium. It contextualizes the relationship between participatory action research (PAR) and teaching in the increasingly popular field of critical action-oriented geography. It considers a number of benefits to student learning from engagement with PAR, drawing on the papers in the collection, and raises some critical questions for future development.
Commentary: Working across Distant Spaces--Connecting Participatory Action Research and Teaching
Pain, Rachel
2009-01-01
This commentary reflects on the key themes and goals of this symposium. It contextualizes the relationship between participatory action research (PAR) and teaching in the increasingly popular field of critical action-oriented geography. It considers a number of benefits to student learning from engagement with PAR, drawing on the papers in the…
Modelling Action Potential Generation and Propagation in Fibroblastic Cells
Torres, J. J.; Cornelisse, L. N.; Harks, E. G. A.; Theuvenet, A. P. R.; Ypey, D. L.
2003-04-01
Using a standard Hodgkin-Huxley (HH) formalism, we present a mathematical model for action potential (AP) generation and intercellular AP propagation in quiescent (serum-deprived) normal rat kidney (NRK) fibroblasts [1], based on the recent experimental identification of the ion channels involved [2]. The principal ion channels described are those of an inwardly rectifying K+ conductance (GKIR), an L-type calcium conductance (GCaL), an intracellular calcium activated Cl- conductance (GCl(Ca)), a residual leak conductance Gleak, and gap junctional channels between the cells (Ggj). The role of each one of these components in the particular shape of the AP wave-form has been analyzed and compared with experimental observations. In addition, we have studied the role of subcellular processes like intracellular calcium dynamics and calcium buffering in AP generation. AP propagation between cells was reconstructed in a hexagonal model of cells coupled by Ggj with physiological conductance values. The model revealed an excitability mechanism of quiescent NRK cells with a particular role of intracellular calcium dynamics. It allows further explorations of the mechanism of signal generation and transmission in NRK cell cultures and its dependence on growth conditions.
Scaling topological charge in the CP3 model using a fixed point action
We define a fixed point action in two-dimensional lattice CPN-1 models. The fixed point action is a classical perfect lattice action, which is expected to show strongly reduced cut-off effects in numerical simulations. Furthermore, the action has scale invariant instanton solutions, which enables us to define a topological charge without topological defects. We present results for the scaling of the topological suceptibility from a Monte Carlo simulation in the CP3 model. (orig.)
A multidimensional decisions modeling framework for built space supply
Farooq, Bilal; Miller, Eric J.; Haider, Murtaza
2013-01-01
The spatial and temporal distribution of built space supply plays an important role in shaping urban form and thus the general travel pattern in an urban area. Within an integrated framework, we are interested in modeling the decisions of a builder in terms of when, where, what type, and how much built space to build. We present a multidimensional discrete-continuous model formulation for the built space supply decisions that are based on expected profit maximization. The framework is applied...
A VECTOR SPACE MODEL FOR INFORMATION RETRIEVAL: A MATLAB APPROACH
Dr. Vinay Chavan
2012-04-01
Full Text Available By and large, three classic framework models have been used in the process of retrieving information: Boolean, Vector Space and Probabilistic. Boolean model is a light weight model which matches the query with precise semantics. Because of its boolean nature, results may be tides, missing partial matching, while on the contrary,vector space model, considering term-frequency, inverse document frequency measures, achieves utmost relevancy in retrieving documents in information retrieval. This paper implements and discusses the issues of information retrieval system with vector space model using MATLAB on Cranfield data collection of aerodynamics domain.
Phase-space dynamics of Bianchi IX cosmological models
The complex phase-space dynamical behaviour of a class of Biachi IX cosmological models is discussed, as the chaotic gravitational collapse due Poincare's homoclinic phenomena, and the n-furcation of periodic orbits and tori in the phase space of the models. Poincare maps which show this behaviour are constructed merically and applications are discussed. (Author)
Space weather products at the Community Coordinated Modeling Center
Hesse, Michael
In addition to supporting space research in the international community, the Community Co-ordinated Modeling Center (CCMC) has as its second objective to bring to apply the power of modern research models toward space weather specification and forecasting. Initially motivated by the objective to test models and to ease the transition of research models to space weather forecasting organization, the CCMC has developed a number of real-time modeling systems, as well as large number of modeling and data products for space weather forecasting. Over time, these activities have evolved into tailored products for partners, as well as into a direct support of the space weather needs within NASA robotic mission community. Accessible through a customizable interface, users within the US or at partnering institutions internationally have access to space weather tools driven by the most advanced space research models. Through partnering with agencies and institutions in the US and abroad, the CCMC strives to set up further data sharing agreements to the benefit of all participating institutions. In this presen-tation, we provide an overview of existing CCMC space weather services and products, and we will explore additional avenues for international collaborations.
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...
A Quotient Space Approximation Model of Multiresolution Signal Analysis
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.
Properties of Brownian Image Models in Scale-Space
Pedersen, Kim Steenstrup
2003-01-01
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...... 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...... of natural images in jet space. The consequence of these results is that the Brownian image model can be used as a least committed model of the covariance structure of the distribution of natural images....
Joint modeling of primary and secondary action in DBM
Koning, Ruud H.; Spring, P.N.; Wansbeek, T.J.
2002-01-01
In this paper we discuss the issue of primary and secondary actions to direct mail offers. Primary action refers to the first responses consumers make toward a direct offer or soliciation. It might represent an order for a product, a request for a catalog or credit card, or a pledge to donate to a c
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.
Advancing Space Weather Modeling Capabilities at the CCMC
Mays, M. Leila; Kuznetsova, Maria; Boblitt, Justin; Chulaki, Anna; MacNeice, Peter; Mendoza, Michelle; Mullinix, Richard; Pembroke, Asher; Pulkkinen, Antti; Rastaetter, Lutz; Shim, Ja Soon; Taktakishvili, Aleksandre; Wiegand, Chiu; Zheng, Yihua
2016-04-01
The Community Coordinated Modeling Center (CCMC, http://ccmc.gsfc.nasa.gov) serves as a community access point to an expanding collection of state-of-the-art space environment models and as a hub for collaborative development on next generation of space weather forecasting systems. In partnership with model developers and the international research and operational communities, the CCMC integrates new data streams and models from diverse sources into end-to-end space weather predictive systems, identifies weak links in data-model & model-model coupling and leads community efforts to fill those gaps. The presentation will focus on the latest model installations at the CCMC and advances in CCMC-led community-wide model validation projects.
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
A Rabbit Ventricular Action Potential Model Replicating Cardiac Dynamics at Rapid Heart Rates
Mahajan, Aman; Shiferaw, Yohannes; Sato, Daisuke; Baher, Ali; Olcese, Riccardo; Xie, Lai-Hua; Yang, Ming-Jim; Chen, Peng-Sheng; Restrepo, Juan G.; Karma, Alain; Garfinkel, Alan; Qu, Zhilin; Weiss, James N.
2008-01-01
Mathematical modeling of the cardiac action potential has proven to be a powerful tool for illuminating various aspects of cardiac function, including cardiac arrhythmias. However, no currently available detailed action potential model accurately reproduces the dynamics of the cardiac action potential and intracellular calcium (Cai) cycling at rapid heart rates relevant to ventricular tachycardia and fibrillation. The aim of this study was to develop such a model. Using an existing rabbit ven...
Palmer, Christopher J; Bigelow, Carol; Van Emmerik, Richard E A
2013-01-01
Soldier equipment compromises task performance as temporal constraints during critical situations and load increase inertial and interactive forces during movement. Methods are necessary to optimise equipment that relate task performance to underlying coordination and perception-action coupling. Employing ecological task analysis and methods from dynamical systems theory, equipment load and coordination was examined during two sub-tasks embedded in combat performance, threat discrimination and dynamic marksmanship. Perception-action coupling was degraded with load during threat discrimination, leading to delays in functional reaction time. Reduced speed and accuracy during dynamic marksmanship under load was related to disrupted segmental coordination and adaptability during postural transitions between targets. These results show how reduced performance under load relates to coordination changes and perception-action coupling. These changes in functional capability are directly related to soldier survivability in combat. The methods employed may aid equipment design towards more optimised performance by modifying equipment or its distribution on humans. PMID:24028557
A FORMAL SPECIFICATION LANGUAGE FOR DYNAMIC STRAND SPACE MODEL
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.
Parallel State Space Construction for Model-Checking
Garavel, Hubert; Mateescu, Radu; Smarandache, Irina
2001-01-01
The verification of concurrent finite-state systems by model-checking often requires to generate (a large part of) the state space of the system under analysis. Because of the state explosion problem, this may be a resource-consuming operation, both in terms of memory and CPU time. In this report, we aim at improving the performances of state space construction by using parallelization techniques. We present parallel algorithms for constructing state spaces (or Labeled Transition Systems) on ...
Background independent effective action from D=1 matrix model
We derive the background independent form of the Das-Jevicki action. The tachyon terms are given to all orders by a generally covariant form of the Das-Jevicki action. The graviton-dilaton sector is the usual low energy effective action. This enables us to examine questions such as the back reaction of the tachyon on the metric. In particular the reason why the usual Liouville term is an exact solution of the conformal invariance conditions, as well as the fact that it has no back reaction, become manifest. We comment on the propagation of a tachyonic perturbation in the background of a black-hole metric. (orig.)
Bootstrapping Critical Ising Model on Three Dimensional Real Projective Space
Nakayama, Yu
2016-04-01
Given conformal data on a flat Euclidean space, we use crosscap conformal bootstrap equations to numerically solve the Lee-Yang model as well as the critical Ising model on a three dimensional real projective space. We check the rapid convergence of our bootstrap program in two dimensions from the exact solutions available. Based on the comparison, we estimate that our systematic error on the numerically solved one-point functions of the critical Ising model on a three dimensional real projective space is less than 1%. Our method opens up a novel way to solve conformal field theories on nontrivial geometries.
A Learning State-Space Model for Image Retrieval
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.
Quantum-Dot Semiconductor Optical Amplifiers: State Space Model versus Rate Equation Model
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.
Zárate, Maria Rodó de
2015-01-01
Introduction In this paper I seek to contribute to feminist geographies of fear by analyzing the ways young feminists in a medium-sized non-metropolitan city of Catalonia manage fear and discomfort in public spaces. Through empirical and analytical methodologies that provide participatory insights to the intersectional and spatial experience of oppression and privilege, I examine their uses and experiences of public space focusing on the personal and collective strategies they develop to f...
Mapping from Speech to Images Using Continuous State Space Models
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...
O(N) Models with Topological Lattice Actions
Bietenholz, Wolfgang; Bögli, Michael; Gerber, Urs; Niedermayer, Ferenc; Pepe, Michele; Wiese, Uwe-Jens; Rejón-Barrera, Fernando G.
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 classic...
A Simulation and Modeling Framework for Space Situational Awareness
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.
A Simulation and Modeling Framework for Space Situational Awareness
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
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.
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
Modeling the Laser Interferometer Space Antenna Optics
Waluschka, Eugene; Pedersen, Tracy R.; McNamara, paul
2005-01-01
The Laser Interferometer Space Antenna (LISA), shown below, will detect gravitational waves produced by objects such as binary black holes or objects falling into black holes (extreme mass ratio inspirals) over a frequency range of l0(exp -4) to 0.1 Hz. Within the conceptual frame work of Newtonian physics, a gravitational wave produces a strain, (Delta)l/l, with magnitudes of the order of Earth based gravitational wave detectors, such as the Laser Interferometer Gravitational-Wave Observatory (LIGO) project, use Michelson interferometers with arm lengths l = 4 km to detect these strains. Earth induced seismic noise limits ground-based instruments detecting gravitational waves with frequencies lower than approx. 1 Hz.
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...
The Einstein-Hilbert action of the space of holomorphic maps from S^2 to CP^k
Alqahtani, L. S.
2013-01-01
Let $\\mathcal{H}_{n,k}(\\Sigma)$ be the space of degree $n\\geq 1$ holomorphic maps from a compact Riemann surface $\\Sigma $ to $\\mathbb{C}P^k$. In the case $\\Sigma=S^2$ and $n=1$, the $L^2$ metric on $\\mathcal{H}_{1,k}(S^2)$ was computed exactly by Speight. In this paper, the Ricci curvature tensor and the scalar curvature on $\\mathcal{H}_{1,k}(S^2)$ are determined explicitly for $k\\geq 2$. An exact direct computation of the Einstein-Hilbert action with respect to the $L^2$ metric on $\\mathcal...
Einstein, the reality of space, and the action-reaction principle
Brown, Harvey R.; Lehmkuhl, Dennis
2013-01-01
Einstein regarded as one of the triumphs of his 1915 theory of gravity --- the general theory of relativity --- that it vindicated the action--reaction principle, while Newtonian mechanics as well as his 1905 special theory of relativity supposedly violated it. In this paper we examine why Einstein came to emphasise this position several years after the development of general relativity. Several key considerations are relevant to the story: the connection Einstein originally saw between Mach'...
An analytic model for the Riemannian space of colors
A scale-invariant generalization of Weinberg's theory of the color space is given. A minimal analytic model is constructed with Gaussian protomeric basis; the metric tensor possesses four independent Killing vectors with an U(1)xSO(1,1) symmetry group. The formalism is applied to dichromatic vision too, and a special model is shown, in which the color space is two-dimensional, however the dominant hues can be identified. 16 refs. (author)
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.
A reference model for space data system interconnection services
Pietras, John; Theis, Gerhard
1993-03-01
The widespread adoption of standard packet-based data communication protocols and services for spaceflight missions provides the foundation for other standard space data handling services. These space data handling services can be defined as increasingly sophisticated processing of data or information received from lower-level services, using a layering approach made famous in the International Organization for Standardization (ISO) Open System Interconnection Reference Model (OSI-RM). The Space Data System Interconnection Reference Model (SDSI-RM) incorporates the conventions of the OSIRM to provide a framework within which a complete set of space data handling services can be defined. The use of the SDSI-RM is illustrated through its application to data handling services and protocols that have been defined by, or are under consideration by, the Consultative Committee for Space Data Systems (CCSDS).
Joint spacing criterion for equivalent continuum model
Currently, the Yucca Mountain Site Characterization Project is investigating the feasibility of the disposal of high-level radioactive waste in the unsaturated Topopah Spring formation. The Topopah Spring formation is a heavily fractured, predominantly vertically jointed, welded tuff, and the potential disposal area is cut by the Ghost Dance fault and bounded by several other fault structures. The joints in the tuff and the faults may have an impact on the emplacement drift or borehole stability, as well as on the movement of fluids through the rock mass. The design of the repository drifts and layout, the waste emplacement scheme, and the thermomechanical performance of the rock mass will be analyzed using various numerical models. These models may be based on different assumptions regarding the representation of the fracture behavior under given applied stresses, and will range from discrete models where individual mechanically active fractures are treated distinctly, to continuum models where the joint behavior is smeared over a representative volume. There is always the question of applicability of a model with respect to a given material domain to be analyzed
A space-averaged model of branched structures
Lopez, Diego; Michelin, Sébastien
2014-01-01
Many biological systems and artificial structures are ramified, and present a high geometric complexity. In this work, we propose a space-averaged model of branched systems for conservation laws. From a one-dimensional description of the system, we show that the space-averaged problem is also one-dimensional, represented by characteristic curves, defined as streamlines of the space-averaged branch directions. The geometric complexity is then captured firstly by the characteristic curves, and secondly by an additional forcing term in the equations. This model is then applied to mass balance in a pipe network and momentum balance in a tree under wind loading.
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
2006-01-01
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 to the power of (-48) square Km. 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.
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.
Frank, M.J.; Scheres, A.P.J.; Sherman, S.J.
2007-01-01
Models of natural action selection implicate fronto-striatal circuits in both motor and cognitive 'actions'. Dysfunction of these circuits leads to decision-making deficits in various populations. We review how computational models provide insights into the mechanistic basis for these deficits in Pa