Sample records for ecological simulation modeling

  1. Ecological Modelling 193 (2006) 271294 A simulation model of sustainability of coastal communities

    E-print Network

    Pierce, Graham

    2006-01-01

    Ecological Modelling 193 (2006) 271­294 A simulation model of sustainability of coastal communities. / Ecological Modelling 193 (2006) 271­294 Fig. 1. Total aquaculture production (EU + EFTA) (FAO Fish Stat). EU and played its part in satisfying an increasing consumer demand for marine fish (Fig. 1). It has been argued

  2. Modelling and simulation of ecological propagation processes: application to fire spread

    Microsoft Academic Search

    Alexandre Muzy; Eric Innocenti; Antoine Aïello; Jean-François Santucci; Paul-antoine Santoni; David R. C. Hill

    2005-01-01

    An important class of ecological problems concerns propagation processes. In ecological modelling, these phenomena generally occur on large scales and are generally difficult to simulate efficiently because of the number of entities. Studies of this kind of phenomena lack genericity and reusability because they are often presented from the point of view of a single domain expert. Simulations made by

  3. ERROR AND UNCERTAINTY ANALYSIS FOR ECOLOGICAL MODELING AND SIMULATION

    EPA Science Inventory

    The main objectives of this project are a) to develop a general methodology for conducting sensitivity and uncertainty analysis and building error budgets in simulation modeling over space and time; and b) to apply that methodology to the assessment of soil erosion through the RU...

  4. Simulation Models for Potato Late Blight Management and Ecology

    Microsoft Academic Search

    G. A. Forbes; W. E. Fry; J. L. Andrade-Piedra; D. Shtienberg

    Late blight of potato has been one of the most widely studied diseases and particular attention has been given to the mathematical\\u000a description of disease development. Several process based simulation models have been developed and this paper focuses primarily\\u000a on several versions developed at Cornell University, and later through collaboration between that University, the International\\u000a Potato Center and the Volcani

  5. Ecological Modelling 193 (2006) 412436 A numerical simulation of the role of zooplankton in C, N and

    E-print Network

    Hambright, K. David

    2006-01-01

    Ecological Modelling 193 (2006) 412­436 A numerical simulation of the role of zooplankton in C, N, IOLR, P.O. Box 447, Migdal 14950, Israel d Limnology and Ecology of Wetlands and Freshwater, MIGAL online 10 November 2005 Abstract We quantify the role of zooplankton in nutrient cycles in Lake Kinneret

  6. Evaluating the ecological benefits of wildfire by integrating fire and ecosystem simulation models

    Microsoft Academic Search

    Robert E. Keane; Eva Karau

    2010-01-01

    Fire managers are now realizing that wildfires can be beneficial because they can reduce hazardous fuels and restore fire-dominated ecosystems. A software tool that assesses potential beneficial and detrimental ecological effects from wildfire would be helpful to fire management. This paper presents a simulation platform called FLEAT (Fire and Landscape Ecology Assessment Tool) that integrates several existing landscape- and stand-level

  7. A FUNCTIONAL DESCRIPTION OF THE ECOLOGICAL DYNAMICS SIMULATION (EDYS) MODEL, WITH APPLICATIONS FOR ARMY AND OTHER FEDERAL LAND MANAGERS

    EPA Science Inventory

    A key component of this capability package is the Ecological Dynamics Simulation (EDYS) model. The model provides the capability to predict responses of training lands to both military and non-military stressors and facilitates linking the cost of training and testing land mainte...

  8. Adding ecology to particle capture models: numerical simulations of capture on a moving cylinder in crossflow.

    PubMed

    Krick, Julian; Ackerman, Josef Daniel

    2015-03-01

    The particle capture efficiency, ?, of systems that remove suspended particles from ambient flow (e.g. suspension feeding, abiotic pollination) has been studied using static collectors in steady flows. Particle deposition on collectors moving due to fluid flow remains largely unknown, despite its ecological relevance. We used numerical modeling to simulate particle deposition on a 2D circular cylinder subject to flow-induced oscillation in a cross flow. Using parameter values relevant to wind pollination and other natural biological systems, we examined the influence of the direction, amplitude and frequency of the oscillation, the Stokes number (Stk=0.01-5, characterizing particle behavior), as well as the Reynolds number (Re=662 and 3309, characterizing flow regime) in steady and unsteady flow, on ?. The numerical model was validated with empirical results for parts of the parameter space. Particle capture occurred via "inertial impaction", "direct interception" and "leeward deposition", as well as via a new mechanism, "collector chasing" for moving collectors. The ? of an oscillating cylinder varied significantly relative to a static cylinder, depending on the parameters used, and on the magnitude of a numerical error that caused loss of particles. This variance of ? was due to a change in relative momentum between the particle and the moving collector, which depends on Re, Stk and the oscillation parameters. Collector oscillation transverse to oncoming flow direction strongly increased ?, whereas collector motion parallel to flow had little effect on capture efficiency. The oscillation also changed leeward capture significantly in some cases. For most conditions, however, leeward deposition was small. Results suggest that collector motion could have significant influence on the particle capture efficiency of natural systems, which indicates the need to incorporate these ecologically more relevant findings into current models. Empirical studies, however, are still necessary to validate these results and provide reliable data. PMID:25496731

  9. A Simulated Stream Ecology Study.

    ERIC Educational Resources Information Center

    Zampella, Robert A.

    1979-01-01

    Describes a simulated field experience to study stream ecology in the classroom. Secondary students determine the composition of the stream community, describe the distribution of the benthic invertebrates, and design a food web. (Author/MA)

  10. Integrating simple stochastic fire spread model with the Regional Hydro-Ecological Simulation System

    NASA Astrophysics Data System (ADS)

    Kennedy, M. C.; McKenzie, D.

    2012-12-01

    Fire has an important role in watershed dynamics, and it is unclear how the interaction between fire and hydrological processes will be modified in a changing climate. Detailed landscape models of fire spread and fire effects require comprehensive data, are computationally intensive, and are subject to cumulative error from uncertainties in many parameters. In contrast, statistical models draw attributes such as extent, frequency, and severity a priori from selected distributions that are estimated from current data, implicitly assuming a stationary driving process that may not hold under climate change. We are designing a relatively simple stochastic model of fire spread (WMFire) that will be coupled with the Regional Hydro-Ecological Simulation System (RHESSys), for projecting the effects of climatic change on mountain watersheds. The model is an extension of exogenously constrained dynamic percolation (ECDP), wherein spread is controlled primarily by a spread probability from burning pixels, and which has been shown to have the capacity to identify dominant controls on cross-scale properties of low-severity fire regimes. Each year RHESSys will pass projected pixel-level values of fuel, fuel moistures, wind speed and wind direction to the fire spread model. Spread probabilities will then be calculated from the fuel load, fuel moisture, and orientation of the pixel relative to the slope gradient and wind direction. The stochastic structure of the spread model will subsume the uncertainties in future patterns of fire spread, fuels and climate. WMFire is being calibrated by and evaluated against current known fire regime properties for watersheds in the Pacific Northwest (USA) using Monte Carlo inference.

  11. Application of a forest-simulation model to assess the energy yield and ecological impact of forest utilization for energy

    SciTech Connect

    Doyle, T W; Shugart, H H; West, D C

    1981-01-01

    This study examines the utilization and management of natural forest lands to meet growing wood-energy demands. An application of a forest simulation model is described for assessing energy returns and long-term ecological impacts of wood-energy harvesting under four general silvicultural practices. Results indicate that moderate energy yields could be expected from mild cutting operations which would significantly effect neither the commercial timber market nor the composition, structure, or diversity of these forests. Forest models can provide an effective tool for determining optimal management strategies that maximize energy returns, minimize environmental detriment, and complement existing land-use plans.

  12. Cosmic emergy based ecological systems modelling

    NASA Astrophysics Data System (ADS)

    Chen, H.; Chen, G. Q.; Ji, X.

    2010-09-01

    Ecological systems modelling based on the unified biophysical measure of cosmic emergy in terms of embodied cosmic exergy is illustrated in this paper with ecological accounting, simulation and scenario analysis, by a case study for the regional socio-economic ecosystem associated with the municipality of Beijing. An urbanized regional ecosystem model with eight subsystems of natural support, agriculture, urban production, population, finance, land area, potential environmental impact, and culture is representatively presented in exergy circuit language with 12 state variables governing by corresponding ecodynamic equations, and 60 flows and auxiliary variables. To characterize the regional socio-economy as an ecosystem, a series of ecological indicators based on cosmic emergy are devised. For a systematic ecological account, cosmic exergy transformities are provided for various dimensions including climate flows, natural resources, industrial products, cultural products, population with educational hierarchy, and environmental emissions. For the urban ecosystem of Beijing in the period from 1990 to 2005, ecological accounting is carried out and characterized in full details. Taking 2000 as the starting point, systems modelling is realized to predict the urban evolution in a one hundred time horizon. For systems regulation, scenario analyses with essential policy-making implications are made to illustrate the long term systems effects of the expected water diversion and rise in energy price.

  13. Physically-Based Modeling of Ecological Restoration

    NASA Astrophysics Data System (ADS)

    Brown, C.; Barros, A. P.

    2001-05-01

    The recovery and continuance of native vegetation communities is the critical component of ecological restoration. As primary producers and basis of the food web, their success will influence and likely control the recovery and sustenance of all higher tropic levels. Intact ecosystems are perfectly designed to produce the vegetation dynamics that they produce. Hence, impacted or altered ecosystems can not be perfectly designed to produce the original vegetation. The alteration of the hydrologic system of the Florida Everglades is causing well-documented changes in the composition of the ecosystem. It is argued that this composition depends on the balance between three vegetation community types, defined here as sawgrass, cattails and periphyton. The factors that may be most critical in the success of the restoration are the factors that will restore the balance between these archetypes. These factors are identified as hydroperiod, water quality (phosphorous concentration) and fire. An investigation of ecological and hydrological models was conducted to evaluate suitability of application to ecological restoration scenarios, such as the vegetation community competition of the Florida Everglades. This investigation revealed aspects of three model types, defined here as ecosystem, hydrologic and competition, are necessary for such a simulation of ecological restoration. A comparison of how each model type treats the common factors of water flow, vegetation dynamics and climate inputs revealed avenues for extension of each model type to better capture the whole system dynamics.

  14. Ecological modeling for applied science

    Microsoft Academic Search

    Forrest Melton; Brad Lobitz; Woody Turner; Edwin Sheffner; John Haynes

    2005-01-01

    Ecological modeling is becoming an increasingly important tool for uniting biological observations with remote sensing and ground-based data networks to develop predictive tools for resource management and human health.The availability of over three petabytes of data from the NASA Earth Observing System Data and Information System (EOSDIS) alone provides an unprecedented opportunity to develop Earth science applications for decision support.

  15. TEMPEST: a Fast Spatially Explicit Model of Ecological Dynamics on Parallel Machines

    E-print Network

    Varela, Carlos

    TEMPEST: a Fast Spatially Explicit Model of Ecological Dynamics on Parallel Machines Bill Maniatty Tom Caraco Boleslaw Szymanski Computer Science Department Department of Biological Sciences Rensselaer the simulation results requires computing global parameters of the ecological environment. Such compu- tations

  16. Spread of insect-vectored plant pathogens: use of simulation models to assess the role of ecological and operational factors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The spread of insect-vectored pathogens is dependent on many factors. As a consequence, it is often difficult to predict effects of manipulating one or more factors on pathogen spread. One method to aid in understanding the role of ecological and operational factors on pathogen spread is the use o...

  17. Ecologic simulation of warm water aquaculture ponds

    SciTech Connect

    Piedrahitu, R.H.; Brune, D.E.; Orlob, G.T.; Tchobanoglous, G.

    1983-06-01

    A generalized ecologic model of a fertilized warm-water aquaculture pond is under development. The model is intended to represent the pond ecosystem and its response to external stimuli. The major physical, chemical and biological processes and parameters are included in the model. A total of 19 state variables are included in the model (dissolved oxygen, alkalinity, pH, ammonia, phytoplankton, etc.). The model is formulated as a system of mass balance equations. The equations include stimulatory and inhibitory effects of environmental parameters on processes taking place in the pond. The equations may be solved for the entire growth period and diurnal as well as seasonal fluctuations may be identified. The ultimate objective of the model is to predict the fish biomass that can be produced in a pond under a given set of environmental conditions.

  18. QUALITATIVE ECOLOGICAL MODELING

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Students construct qualitative models of an ecosystem and use the models to evaluate the direct and indirect effects that may result from perturbations to the ecosystem. Qualitative modeling is described for use in two procedures, each with different educational goals and student backgrounds in min...

  19. Comment on modeling ecological response to climatic change

    Microsoft Academic Search

    George P. Malanson

    1993-01-01

    Researchers have developed many computer simulation models to project ecological responses to climatic change. Three general types of models are examined: transfer functions, stand models, and physiological models. Criteria for evaluation are, first, ability to represent observed and theoretical responses to climatic change i.e., geographical migration, individualistic responses, and disequilibrium or inertia, and second, ability to provide useful information on

  20. Spatial uncertainty and ecological models

    SciTech Connect

    Jager, Yetta [ORNL; King, Anthony Wayne [ORNL

    2004-07-01

    Applied ecological models that are used to understand and manage natural systems often rely on spatial data as input. Spatial uncertainty in these data can propagate into model predictions. Uncertainty analysis, sensitivity analysis, error analysis, error budget analysis, spatial decision analysis, and hypothesis testing using neutral models are all techniques designed to explore the relationship between variation in model inputs and variation in model predictions. Although similar methods can be used to answer them, these approaches address different questions. These approaches differ in (a) whether the focus is forward or backward (forward to evaluate the magnitude of variation in model predictions propagated or backward to rank input parameters by their influence); (b) whether the question involves model robustness to large variations in spatial pattern or to small deviations from a reference map; and (c) whether processes that generate input uncertainty (for example, cartographic error) are of interest. In this commentary, we propose a taxonomy of approaches, all of which clarify the relationship between spatial uncertainty and the predictions of ecological models. We describe existing techniques and indicate a few areas where research is needed.

  1. Modeling the coupling of ocean ecology and biogeochemistry

    Microsoft Academic Search

    S. Dutkiewicz; M. J. Follows; J. G. Bragg

    2009-01-01

    Abstract. 8 We examine the interplay between ecology and biogeochemical cycles in the context 9 of a global three-dimensional ocean model where self-assembling phytoplankton commu- 10 nities emerge from a wide set of potentially viable cell types. We consider the complex 11 model solutions in the light of resource competition theory. The simulations have clear 12 and plausible organization of

  2. Ecological Modelling 146 (2001) 263273 Applications of symbolic machine learning to ecological

    E-print Network

    Dzeroski, Saso

    2001-01-01

    Ecological Modelling 146 (2001) 263­273 Applications of symbolic machine learning to ecological machine learning methods to ecological modelling problems are numerous and varied, ranging from modelling for chemicals. This paper gives an overview of machine learning applications to ecological modelling, focussing

  3. Ecological modeling for applied science

    NASA Astrophysics Data System (ADS)

    Melton, Forrest; Lobitz, Brad; Turner, Woody; Sheffner, Edwin; Haynes, John

    Ecological modeling is becoming an increasingly important tool for uniting biological observations with remote sensing and ground-based data networks to develop predictive tools for resource management and human health.The availability of over three petabytes of data from the NASA Earth Observing System Data and Information System (EOSDIS) alone provides an unprecedented opportunity to develop Earth science applications for decision support. In combination with data networks such as the U.S. National Oceanic and Atmospheric Administration's National Climate Data Center, the nonprofit NatureServe's network of biological inventories, the National Environmental Public Health Tracking Network of the U.S. Centers for Disease Control and Prevention, and many others, there is a vast wealth of Earth observation data on parameters as diverse as land cover, sea surface temperature, precipitation, species distribution, and disease occurrence.

  4. Ecological Impacts of the Cerro Grande Fire: Predicting Elk Movement and Distribution Patterns in Response to Vegetative Recovery through Simulation Modeling October 2005

    SciTech Connect

    S.P. Rupp

    2005-10-01

    In May 2000, the Cerro Grande Fire burned approximately 17,200 ha in north-central New Mexico as the result of an escaped prescribed burn initiated by Bandelier National Monument. The interaction of large-scale fires, vegetation, and elk is an important management issue, but few studies have addressed the ecological implications of vegetative succession and landscape heterogeneity on ungulate populations following large-scale disturbance events. Primary objectives of this research were to identify elk movement pathways on local and landscape scales, to determine environmental factors that influence elk movement, and to evaluate movement and distribution patterns in relation to spatial and temporal aspects of the Cerro Grande Fire. Data collection and assimilation reflect the collaborative efforts of National Park Service, U.S. Forest Service, and Department of Energy (Los Alamos National Laboratory) personnel. Geographic positioning system (GPS) collars were used to track 54 elk over a period of 3+ years and locational data were incorporated into a multi-layered geographic information system (GIS) for analysis. Preliminary tests of GPS collar accuracy indicated a strong effect of 2D fixes on position acquisition rates (PARs) depending on time of day and season of year. Slope, aspect, elevation, and land cover type affected dilution of precision (DOP) values for both 2D and 3D fixes, although significant relationships varied from positive to negative making it difficult to delineate the mechanism behind significant responses. Two-dimensional fixes accounted for 34% of all successfully acquired locations and may affect results in which those data were used. Overall position acquisition rate was 93.3% and mean DOP values were consistently in the range of 4.0 to 6.0 leading to the conclusion collar accuracy was acceptable for modeling purposes. SAVANNA, a spatially explicit, process-oriented ecosystem model, was used to simulate successional dynamics. Inputs to the SAVANNA included a land cover map, long-term weather data, soil maps, and a digital elevation model. Parameterization and calibration were conducted using field plots. Model predictions of herbaceous biomass production and weather were consistent with available data and spatial interpolations of snow were considered reasonable for this study. Dynamic outputs generated by SAVANNA were integrated with static variables, movement rules, and parameters developed for the individual-based model through the application of a habitat suitability index. Model validation indicated reasonable model fit when compared to an independent test set. The finished model was applied to 2 realistic management scenarios for the Jemez Mountains and management implications were discussed. Ongoing validation of the individual-based model presented in this dissertation provides an adaptive management tool that integrates interdisciplinary experience and scientific information, which allows users to make predictions about the impact of alternative management policies.

  5. Ecological Modelling 187 (2005) 179200 Eutrophication model for Lake Washington (USA)

    E-print Network

    Arhonditsis, George B.

    2005-01-01

    Ecological Modelling 187 (2005) 179­200 Eutrophication model for Lake Washington (USA) Part II Abstract We developed a complex eutrophication model to simulate the current chemical and biological of the present eutrophication model with a hydrodynamic model with enhanced vertical resolution will allow more

  6. Modeling Marine Phage Ecology Joseph M. Mahaffy

    E-print Network

    Mahaffy, Joseph M.

    liter sample · Filter water so only phage particles remain · Extract the phage DNA · Randomly breakModeling Marine Phage Ecology Joseph M. Mahaffy Nonlinear Dynamical Systems Group Computational/3 #12;Outline · Introduction to Marine Phage · Discuss Biological Experiments · Contig Analysis

  7. Virtual Epidemics Ecological Modeling on a Parallel Machine Bill Maniatty 1 , Boleslaw Szymanski 2 , Tom Caraco 3

    E-print Network

    Maniatty, William A.

    and the habitat. Computer simulation of population densities and associated spatial patterns in ecological modelsVirtual Epidemics ­ Ecological Modeling on a Parallel Machine Bill Maniatty 1 , Boleslaw Szymanski of ecological interactions is fundamentally important to understanding population dynamics, community stability

  8. GLOBAL CHANGE ECOLOGY -ORIGINAL RESEARCH Local effects of a global problem: modelling the risk of parasite-

    E-print Network

    Poulin, Robert

    cascading effects through ecological networks such as food webs (Ottersen et al. 2001; Stenseth et al. 2002GLOBAL CHANGE ECOLOGY - ORIGINAL RESEARCH Local effects of a global problem: modelling the risk to make realistic predictions about these conse- quences. Here, we adapt a simulation model developed

  9. WASP TRANSPORT MODELING AND WASP ECOLOGICAL MODELING

    EPA Science Inventory

    A combination of lectures, demonstrations, and hands-on excercises will be used to introduce pollutant transport modeling with the U.S. EPA's general water quality model, WASP (Water Quality Analysis Simulation Program). WASP features include a user-friendly Windows-based interfa...

  10. Jan 16 Conceptual models of ecological systems Why is Integration Needed in Ecology?

    E-print Network

    Hansen, Andrew J.

    Jan 16 Conceptual models of ecological systems #12;Why is Integration Needed in Ecology? Great advances have been made by dividing ecology into subdisciplines. But too much focus on subdisciplines has also hindered ecology · too little study of the interface between disciplines · tended to narrow focus

  11. Exploring the Realized Niche: Simulated Ecological Mapping with a Microcomputer.

    ERIC Educational Resources Information Center

    Kent, J. W.

    1983-01-01

    Describes a computer program based upon field observations of littoral zonation modified by a small stream. The program employs user-defined color graphic characters to display simulated ecological maps representing the patterning of organisms in response to local values of niche limiting factors. (Author/JN)

  12. Models, Traffic Models, Simulation, and Traffic Simulation

    Microsoft Academic Search

    Jaume Barceló

    \\u000a This introductory chapter to a book on traffic simulation fundamentals is aimed at setting up a comprehensive framework for\\u000a simulation as a well-established and grounded OR technique and its specificities when applied to traffic systems; the main\\u000a approaches to traffic simulation and the principles of traffic simulation model building; the fundamentals of traffic flow\\u000a theory and its application to traffic

  13. Ecological Modelling 187 (2005) 140178 Eutrophication model for Lake Washington (USA)

    E-print Network

    Arhonditsis, George B.

    2005-01-01

    Ecological Modelling 187 (2005) 140­178 Eutrophication model for Lake Washington (USA) Part I eutrophication model that has been developed to simulate plankton dynamics in Lake Washington, USA. Because loading scenarios. © 2005 Elsevier B.V. All rights reserved. Keywords: Eutrophication; Lake Washington

  14. Ecological Modelling 190 (2006) 159170 Animal dispersal modelling: Handling landscape

    E-print Network

    Alvarez, Nadir

    2006-01-01

    ; Landscape feature; Object-oriented design; Spatially explicit model Corresponding author at: The EcologyEcological Modelling 190 (2006) 159­170 Animal dispersal modelling: Handling landscape features Abstract Animal dispersal in a fragmented landscape depends on the complex interaction between landscape

  15. An Interdisciplinary Model for Teaching Evolutionary Ecology.

    ERIC Educational Resources Information Center

    Coletta, John

    1992-01-01

    Describes a general systems evolutionary model and demonstrates how a previously established ecological model is a function of its past development based on the evolution of the rock, nutrient, and water cycles. Discusses the applications of the model in environmental education. (MDH)

  16. A Global Lake Ecological Observatory Network (GLEON) for synthesising high-frequency sensor data for validation of deterministic ecological models

    USGS Publications Warehouse

    David, Hamilton P; Carey, Cayelan C; Arvola, Lauri; Arzberger, Peter; Brewer, Carol A.; Cole, Jon J; Gaiser, Evelyn; Hanson, Paul C.; Ibelings, Bas W; Jennings, Eleanor; Kratz, Tim K; Lin, Fang-Pang; McBride, Christopher G; de Motta Marques, David; Muraoka, Kohji; Nishri, Ami; Qin, Boqiang; Read, Jordan S.; Rose, Kevin C.; Ryder, Elizabeth; Weathers, Kathleen C.; Zhu, Guangwei; Trolle, Dennis; Brookes, Justin D

    2014-01-01

    A Global Lake Ecological Observatory Network (GLEON; www.gleon.org) has formed to provide a coordinated response to the need for scientific understanding of lake processes, utilising technological advances available from autonomous sensors. The organisation embraces a grassroots approach to engage researchers from varying disciplines, sites spanning geographic and ecological gradients, and novel sensor and cyberinfrastructure to synthesise high-frequency lake data at scales ranging from local to global. The high-frequency data provide a platform to rigorously validate process- based ecological models because model simulation time steps are better aligned with sensor measurements than with lower-frequency, manual samples. Two case studies from Trout Bog, Wisconsin, USA, and Lake Rotoehu, North Island, New Zealand, are presented to demonstrate that in the past, ecological model outputs (e.g., temperature, chlorophyll) have been relatively poorly validated based on a limited number of directly comparable measurements, both in time and space. The case studies demonstrate some of the difficulties of mapping sensor measurements directly to model state variable outputs as well as the opportunities to use deviations between sensor measurements and model simulations to better inform process understanding. Well-validated ecological models provide a mechanism to extrapolate high-frequency sensor data in space and time, thereby potentially creating a fully 3-dimensional simulation of key variables of interest.

  17. Ecological Applications, 8(2), 1998, pp. 365378 1998 by the Ecological Society of America

    E-print Network

    heterogeneity; host-parasite model; Ixodes; land- scape ecology; Lyme disease; New York, USA; Peromyscus leucopus; simulation model; ticks. INTRODUCTION Classic ecological theory assumes spatial homoge- neity

  18. Stochastic ecological network occupancy (SENO) models: a new tool for modeling ecological networks across spatial scales

    Microsoft Academic Search

    Kevin D. Lafferty; Jennifer A. Dunne

    2010-01-01

    Stochastic ecological network occupancy (SENO) models predict the probability that species will occur in a sample of an ecological\\u000a network. In this review, we introduce SENO models as a means to fill a gap in the theoretical toolkit of ecologists. As input,\\u000a SENO models use a topological interaction network and rates of colonization and extinction (including consumer effects) for\\u000a each

  19. Social Ecological Model of Multilevel Influences on Diet

    Cancer.gov

    Social Ecological Model of Multilevel Influences on Diet Social ecological model of multilevel influences on diet: A graphic depicting concentric spheres, with the innermost sphere representing the Individual level and text labels corresponding to key

  20. Social Ecological Model Analysis for ICT Integration

    ERIC Educational Resources Information Center

    Zagami, Jason

    2013-01-01

    ICT integration of teacher preparation programmes was undertaken by the Australian Teaching Teachers for the Future (TTF) project in all 39 Australian teacher education institutions and highlighted the need for guidelines to inform systemic ICT integration approaches. A Social Ecological Model (SEM) was used to positively inform integration…

  1. Simulating ecological changes caused by marine energy devices

    NASA Astrophysics Data System (ADS)

    Schuchert, Pia; Elsaesser, Bjoern; Pritchard, Daniel; Kregting, Louise

    2015-04-01

    Marine renewable energy from wave and tidal technology has the potential to contribute significantly globally to energy security for future generations. However common to both tidal and wave energy extraction systems is concern regarding the potential environmental consequences of the deployment of the technology as environmental and ecological effects are so far poorly understood. Ecological surveys and studies to investigate the environmental impacts are time consuming and costly and are generally reactive; a more efficient approach is to develop 2 and 3D linked hydrodynamic-ecological modelling which has the potential to be proactive and to allow forecasting of the effects of array installation. The objective of the study was to explore tools which can help model and evaluate possible far- and near field changes in the environment and ecosystem caused by the introduction of arrays of marine energy devices. Using the commercial software, MIKE by DHI, we can predict and model possible changes in the ecosystem. MIKE21 and ECOLab modelling software provide the opportunity to couple high level hydrodynamic models with process based ecological models and/or agent based models (ABM). The flow solutions of the model were determined in an idealised tidal basin with the dimensions similar to that of Strangford Lough, Northern Ireland, a body of water renowned for the location of the first grid-connected tidal turbine, SeaGen. In the first instance a simple process oriented ecological NPZD model was developed which are used to model marine and freshwater systems describing four state variables, Nutrient, Phytoplankton, Zooplankton and Detritus. The ecological model was run and evaluated under two hydrodynamic scenarios of the idealised basin. This included no tidal turbines (control) and an array of 55 turbines, an extreme scenario. Whilst an array of turbines has an effect on the hydrodynamics of the Lough, it is unlikely to see an extreme effect on the NPZD model. Further assessment on primary productivity and filter feeders is currently being implemented to assess impacts on these biological systems. Using MIKE software opens up many further possibilities to allow insights into the impacts of marine energy devices on the ecosystem.

  2. Modelling macroevolutionary patterns: An ecological perspective

    NASA Astrophysics Data System (ADS)

    Solé, R. V.

    Complex ecosystems display well-defined macroscopic regularities suggesting that some generic dynamical rules operate at the ecosystem level where the relevance of the single-species features is rather weak. Most evolutionary theory deals with genes/species as the units of selection operating on populations. However, the role of ecological networks and external perturbations seems to be at least as important as microevolutionary events based on natural selection operating at the smalle st levels. Here we review some of the recent theoretical approximations to ecosystem evolution based on network dynamics. It is suggested that the evolutionary dynamics of ecological networks underlie fundamental laws of ecology-level dynamics which naturally decouple micro from macroevolutionary dynamics. Using simple models of macroevolution, most of the available statistical information obtained from the fossil record is remarkably well reproduced and explained within a new theoretical framework.

  3. Aviation Safety Simulation Model

    NASA Technical Reports Server (NTRS)

    Houser, Scott; Yackovetsky, Robert (Technical Monitor)

    2001-01-01

    The Aviation Safety Simulation Model is a software tool that enables users to configure a terrain, a flight path, and an aircraft and simulate the aircraft's flight along the path. The simulation monitors the aircraft's proximity to terrain obstructions, and reports when the aircraft violates accepted minimum distances from an obstruction. This model design facilitates future enhancements to address other flight safety issues, particularly air and runway traffic scenarios. This report shows the user how to build a simulation scenario and run it. It also explains the model's output.

  4. Rainfall simulation experiments in ecological and conventional vineyards.

    NASA Astrophysics Data System (ADS)

    Adrian, Alexander; Brings, Christine; Rodrigo Comino, Jesús; Iserloh, Thomas; Ries, Johannes B.

    2015-04-01

    In October 2014, the Trier University started a measurement series, which defines, compares and evaluates the behavior of runoff and soil erosion with different farming productions in vineyards. The research area is located in Kanzem, a traditional wine village in the Saar Valley (Rheinland-Palatinate, Germany). The test fields show different cultivation methods: ecological (with natural vegetation cover under and around the vines) and conventional cultivated rows of wine. By using the small portable rainfall simulator of Trier University it shall be proved if the assumption that there is more runoff and soil erosion in the conventional part than in the ecological part of the tillage system. Rainfall simulations assess the generation of overland flow, soil erosion and infiltration. So, a trend of soil erosion and runoff of the different cultivation techniques are noted. The objective of this work is to compare the geomorphological dynamics of two different tillage systems. Therefore, 30 rainfall simulations plots were evenly distributed on a west exposition hillside with different slope angels (8-25°), vegetation- and stone-covers. In concrete, the plot surface reaches from strongly covered soil across lithoidal surfaces to bare soil often with compacted lanes of typical using machines. In addition, by using the collected substrate, an estimation and distribution of the grain size of the eroded material shall be given. The eroded substrate is compared to soil samples of the test plots. The first results have shown that there is slightly more runoff and soil erosion in the ecological area than on the conventional part of the vineyard.

  5. Modelling the ecological niche from functional traits

    PubMed Central

    Kearney, Michael; Simpson, Stephen J.; Raubenheimer, David; Helmuth, Brian

    2010-01-01

    The niche concept is central to ecology but is often depicted descriptively through observing associations between organisms and habitats. Here, we argue for the importance of mechanistically modelling niches based on functional traits of organisms and explore the possibilities for achieving this through the integration of three theoretical frameworks: biophysical ecology (BE), the geometric framework for nutrition (GF) and dynamic energy budget (DEB) models. These three frameworks are fundamentally based on the conservation laws of thermodynamics, describing energy and mass balance at the level of the individual and capturing the prodigious predictive power of the concepts of ‘homeostasis’ and ‘evolutionary fitness’. BE and the GF provide mechanistic multi-dimensional depictions of climatic and nutritional niches, respectively, providing a foundation for linking organismal traits (morphology, physiology, behaviour) with habitat characteristics. In turn, they provide driving inputs and cost functions for mass/energy allocation within the individual as determined by DEB models. We show how integration of the three frameworks permits calculation of activity constraints, vital rates (survival, development, growth, reproduction) and ultimately population growth rates and species distributions. When integrated with contemporary niche theory, functional trait niche models hold great promise for tackling major questions in ecology and evolutionary biology. PMID:20921046

  6. Spatially-Explicit Simulation Modeling of Ecological Response to Climate Change: Methodological Considerations in Predicting Shifting Population Dynamics of Infectious Disease Vectors

    PubMed Central

    Dhingra, Radhika; Jimenez, Violeta; Chang, Howard H.; Gambhir, Manoj; Fu, Joshua S.; Liu, Yang; Remais, Justin V.

    2014-01-01

    Poikilothermic disease vectors can respond to altered climates through spatial changes in both population size and phenology. Quantitative descriptors to characterize, analyze and visualize these dynamic responses are lacking, particularly across large spatial domains. In order to demonstrate the value of a spatially explicit, dynamic modeling approach, we assessed spatial changes in the population dynamics of Ixodes scapularis, the Lyme disease vector, using a temperature-forced population model simulated across a grid of 4 × 4 km cells covering the eastern United States, using both modeled (Weather Research and Forecasting (WRF) 3.2.1) baseline/current (2001–2004) and projected (Representative Concentration Pathway (RCP) 4.5 and RCP 8.5; 2057–2059) climate data. Ten dynamic population features (DPFs) were derived from simulated populations and analyzed spatially to characterize the regional population response to current and future climate across the domain. Each DPF under the current climate was assessed for its ability to discriminate observed Lyme disease risk and known vector presence/absence, using data from the US Centers for Disease Control and Prevention. Peak vector population and month of peak vector population were the DPFs that performed best as predictors of current Lyme disease risk. When examined under baseline and projected climate scenarios, the spatial and temporal distributions of DPFs shift and the seasonal cycle of key questing life stages is compressed under some scenarios. Our results demonstrate the utility of spatial characterization, analysis and visualization of dynamic population responses—including altered phenology—of disease vectors to altered climate. PMID:24772388

  7. Implicit assimilation for marine ecological models

    NASA Astrophysics Data System (ADS)

    Weir, B.; Miller, R.; Spitz, Y. H.

    2012-12-01

    We use a new data assimilation method to estimate the parameters of a marine ecological model. At a given point in the ocean, the estimated values of the parameters determine the behaviors of the modeled planktonic groups, and thus indicate which species are dominant. To begin, we assimilate in situ observations, e.g., the Bermuda Atlantic Time-series Study, the Hawaii Ocean Time-series, and Ocean Weather Station Papa. From there, we estimate the parameters at surrounding points in space based on satellite observations of ocean color. Given the variation of the estimated parameters, we divide the ocean into regions meant to represent distinct ecosystems. An important feature of the data assimilation approach is that it refines the confidence limits of the optimal Gaussian approximation to the distribution of the parameters. This enables us to determine the ecological divisions with greater accuracy.

  8. Proceedings of the IASTED International Conference Modelling And Simulation

    E-print Network

    Imperial College, London

    Proceedings of the IASTED International Conference Modelling And Simulation May 5­8, Philadelphia, USA Parallel Simulation of Plankton Ecology S. Al­Battran, A.J. Field Department of Computing R and Medicine 180 Queen's Gate, London SW7 2BZ. Abstract This paper describes a parallel simulation tool

  9. Hierarchical Bayesian Models for Predicting The Spread of Ecological Processes

    E-print Network

    , 222 Math Science Building, Columbia, MO 65211; wikle@stat.missouri.edu 1 #12;INTRODUCTION EcologicalHierarchical Bayesian Models for Predicting The Spread of Ecological Processes Christopher K. Wikle Department of Statistics, University of Missouri To appear: Ecology June 10, 2002 Key Words: Bayesian

  10. A percolation model of ecological flows

    SciTech Connect

    Gardner, R.H.; Turner, M.G.; Dale, V.H.; O'Neill, R.V.

    1988-01-01

    The boundary zone between adjacent communities has long been recognized as a functionally important component of ecosystems. The diversity and abundance of species, the flow and accumulation of material and energy, and the propagation of disturbances may all be affected by landscape boundaries. However, the spatial arrangement of different habitats and their boundaries has received little direct study. The difficulty in studying landscape boundaries has been due, in part, to the variety of responses of organisms to ecotones. Therefore, definitive tests of relationships between ecological processes and the pattern of landscape boundaries will be greatly assisted by developing a standard against which comparisons can be made. Neutral models can define this standard by producing the expected'' Poisson distribution have been well established, but a general approach for relating ecological processes and landscape patterns must still be defined. The purpose of this chapter is to illustrate how neutral models that are developed from percolation theory can be used to address the problem How do ecological system boundaries influence biotic diversity and the flow of energy, information and materials '' 26 refs., 4 figs., 1 tab.

  11. Theory Modeling and Simulation

    SciTech Connect

    Shlachter, Jack [Los Alamos National Laboratory

    2012-08-23

    Los Alamos has a long history in theory, modeling and simulation. We focus on multidisciplinary teams that tackle complex problems. Theory, modeling and simulation are tools to solve problems just like an NMR spectrometer, a gas chromatograph or an electron microscope. Problems should be used to define the theoretical tools needed and not the other way around. Best results occur when theory and experiments are working together in a team.

  12. Reconciling empirical ecology with neutral community models.

    PubMed

    Holyoak, Marcel; Loreau, Michel

    2006-06-01

    Neutral community models embody the idea that individuals are ecologically equivalent, having equal fitness over all environmental conditions, and describe how the spatial dynamics and speciation of such individuals can produce a wide range of patterns of distribution, diversity, and abundance. Neutral models have been controversial, provoking a rush of tests and comments. The debate has been spurred by the suggestion that we should test mechanisms. However, the mechanisms and the spatial scales of interest have never clearly been described, and consequently, the tests have often been only peripherally relevant. At least two mechanisms are present in spatially structured neutral models. Dispersal limitation causes clumping of a species, which increases the strength of intraspecific competition and reduces the strength of interspecific competition. This may prolong coexistence and enhance local and regional diversity. Speciation is present in some neutral models and gives a donor-controlled input of new species, many of which remain rare or are short lived, but which directly add to species diversity. Spatial scale is an important consideration in neutral models. Ecological equivalence and equal fitness have implicit spatial scales because dispersal limitation and its emergent effects operate at population levels, and populations and communities are defined at a chosen spatial scale in recent neutral models; equality is measured relative to a metacommunity, and this necessitates defining the spatial scale of that metacommunity. Furthermore, dispersal has its own scales. Thorough empirical tests of neutral models will require both tests of mechanisms and pattern-producing ability, and will involve coupling theoretical models and experiments. PMID:16869411

  13. 1 NUMERICAL MODELS OF SALT MARSH 2 EVOLUTION: ECOLOGICAL, GEOMORPHIC,

    E-print Network

    1 NUMERICAL MODELS OF SALT MARSH 2 EVOLUTION: ECOLOGICAL, GEOMORPHIC, 3 AND CLIMATIC FACTORS 4: Fagherazzi, S., et al. (2011), Numerical models of salt marsh evolution: Ecological, geomorphic, and climatic and mediates sediment transport processes. Here 12 we present a broad overview of recent numerical models

  14. Modeling the coupling of ocean ecology and biogeochemistry

    Microsoft Academic Search

    S. Dutkiewicz; M. J. Follows; J. G. Bragg

    2009-01-01

    We examine the interplay between ecology and biogeochemical cycles in the context of a global three-dimensional ocean model where self-assembling phytoplankton communities emerge from a wide set of potentially viable cell types. We consider the complex model solutions in the light of resource competition theory. The emergent community structures and ecological regimes vary across different physical environments in the model

  15. Cellular automata as a paradigm for ecological modeling

    Microsoft Academic Search

    P. Hogeweg

    1988-01-01

    We review cellular automata as a modeling formalism and discuss how it can be used for modeling (spatial) ecological processes. The implications of this modeling paradigm for ecological observation are stressed. Finally we discuss some shortcom- ings of the cellular-automaton formalism and mention some extensions and generaliza- tions which may remedy these shortcomings.

  16. AGRICULTURAL SIMULATION MODEL (AGSIM)

    EPA Science Inventory

    AGSIM is a large-scale econometric simulation model of regional crop and national livestock production in the United States. The model was initially developed to analyze the aggregate economic impacts of a wide variety issues facing agriculture, such as technological change, pest...

  17. AN INTRODUCTION TO THE PRACTICE OF ECOLOGICAL MODELING

    EPA Science Inventory

    No abstract. Modeling has become an important tool in the study of ecological systems, as a scan of the table of contents of any major ecological journal makes abundently clear. The development of a conceptual model can be an integral part of designing and carrying out any resear...

  18. Ecological Niche Modeling of Bacillus anthracis on Three Continents: Evidence for Genetic-Ecological Divergence?

    PubMed Central

    Mullins, Jocelyn C.; Garofolo, Giuliano; Van Ert, Matthew; Fasanella, Antonio; Lukhnova, Larisa; Hugh-Jones, Martin E.; Blackburn, Jason K.

    2013-01-01

    We modeled the ecological niche of a globally successful Bacillus anthracis sublineage in the United States, Italy and Kazakhstan to better understand the geographic distribution of anthrax and potential associations between regional populations and ecology. Country-specific ecological-niche models were developed and reciprocally transferred to the other countries to determine if pathogen presence could be accurately predicted on novel landscapes. Native models accurately predicted endemic areas within each country, but transferred models failed to predict known occurrences in the outside countries. While the effects of variable selection and limitations of the genetic data should be considered, results suggest differing ecological associations for the B. anthracis populations within each country and may reflect niche specialization within the sublineage. Our findings provide guidance for developing accurate ecological niche models for this pathogen; models should be developed regionally, on the native landscape, and with consideration to population genetics. Further genomic analysis will improve our understanding of the genetic-ecological dynamics of B. anthracis across these countries and may lead to more refined predictive models for surveillance and proactive vaccination programs. Further studies should evaluate the impact of variable selection of native and transferred models. PMID:23977300

  19. A complementary ecological model of the coordinated school health program.

    PubMed

    Lohrmann, David K

    2008-01-01

    A complementary ecological model of the coordinated school health program (CSHP) reflecting 20 years of evolved changes is proposed. Ecology refers to the complex interrelationship among intrapersonal factors, interpersonal processes and primary groups, institutional factors, community factors, and public policy. Public health and child development theories that incorporate the influence of personal and social environments on health behavior, along with models that incorporate the influence of ecology, were consulted. Concepts from several models were combined with the eight components of CSHP to formulate an ecological model involving six program and services components in an inner circle surrounded by four concentric rings representing the healthy school environment, essential structures of CSHP, local school district governance, and family and community involvement. This complementary ecological model is intended to serve as an additional conceptual approach to CSHP practice, evaluation, and research, and should prove especially useful to practitioners and researchers who already have a fundamental understanding of CSHP. PMID:19711650

  20. Ecological Modelling 189 (2005) 151167 Habitat and exposure modelling for ecological risk assessment: A

    E-print Network

    Hodgson, Michael E.

    2005-01-01

    information system (GIS)-based Monte Carlo simulation model. The model was applied to the raccoons (Procyon lotor) on the Savannah River Site (SRS), a former nuclear production and current research facility

  1. QUANTITATIVE ECOLOGY A Simple Numerical Model of the Flight Behavior of Small Insects in

    E-print Network

    Geerts, Bart

    QUANTITATIVE ECOLOGY A Simple Numerical Model of the Flight Behavior of Small Insects of rising air, and that the insects in those plumes oppose the updrafts at a rate that increases as the updrafts become stronger. In this paper, a simple numerical simulation of the airßow Þeld and insect

  2. Hydrodynamic and Ecological Assessment of Nearshore Restoration: A Modeling Study

    SciTech Connect

    Yang, Zhaoqing; Sobocinski, Kathryn L.; Heatwole, Danelle W.; Khangaonkar, Tarang; Thom, Ronald M.; Fuller, Roger

    2010-04-10

    Along the Pacific Northwest coast, much of the estuarine habitat has been diked over the last century for agricultural land use, residential and commercial development, and transportation corridors. As a result, many of the ecological processes and functions have been disrupted. To protect coastal habitats that are vital to aquatic species, many restoration projects are currently underway to restore the estuarine and coastal ecosystems through dike breaches, setbacks, and removals. Information on physical processes and hydrodynamic conditions are critical for the assessment of the success of restoration actions. Restoration of a 160- acre property at the mouth of the Stillaguamish River in Puget Sound has been proposed. The goal is to restore native tidal habitats and estuary-scale ecological processes by removing the dike. In this study, a three-dimensional hydrodynamic model was developed for the Stillaguamish River estuary to simulate estuarine processes. The model was calibrated to observed tide, current, and salinity data for existing conditions and applied to simulate the hydrodynamic responses to two restoration alternatives. Responses were evaluated at the scale of the restoration footprint. Model data was combined with biophysical data to predict habitat responses at the site. Results showed that the proposed dike removal would result in desired tidal flushing and conditions that would support four habitat types on the restoration footprint. At the estuary scale, restoration would substantially increase the proportion of area flushed with freshwater (< 5 ppt) at flood tide. Potential implications of predicted changes in salinity and flow dynamics are discussed relative to the distribution of tidal marsh habitat.

  3. A Complementary Ecological Model of the Coordinated School Health Program

    ERIC Educational Resources Information Center

    Lohrmann, David K.

    2010-01-01

    Background: A complementary ecological model of the coordinated school health program (CSHP) reflecting 20 years of evolved changes is proposed. Ecology refers to the complex interrelationship between intrapersonal factors, interpersonal processes and primary groups, institutional factors, community factors, and public policy. Methods: Public…

  4. Development and Application of Computer Simulation Tools for Ecological Risk Assessment

    Microsoft Academic Search

    Haiyi Lu; Lisa Axe; Trevor A. Tyson

    2003-01-01

    Based on a review of available models for ecological risk estimation, most are site-specific and their applications are limited. However, general models, which can be easily adapted to other sites, remain few, in addition, they are simple and associated with significant uncertainties. In this paper, an approach is introduced for an ecological risk assessment (ERA) model that can be modified

  5. Designing wetlands for controlling coal mine drainage: an ecologic-economic modelling approach

    Microsoft Academic Search

    Kimberly Anne Baker; M. Siobhan Fennessy; William J. Mitsch

    1991-01-01

    Baker, K.A., Fennessy, M.S. and Mitsch, W.J., 1991. Designing wetlands for controlling coal mine drainage: an ecologic-economic modelling approach. Ecol. Econ., 3: l-24. A simulation model is developed of the efficiency and economics of an application of ecotechnology - using a created wetland to receive and treat coal mine drainage. The model examines the role of loading rates of iron

  6. Mission lifecycle modeling and simulation

    Microsoft Academic Search

    Meemong Lee; Richard J. Weidner; Wenwen Lu

    2000-01-01

    Mission synthesis and simulation research at JPL addresses mission model taxonomy, progressive lifecycle representation, model-based design, and simulation-in-the-loop design. The Virtual Mission (VM) project integrates the research activities and implements a virtual mission lifecycle to enable a globally optimal mission. The VM is composed of three interacting modeling and simulation layers: a mission model architecture layer, a mission system simulation

  7. Delay modeling in logic simulation

    SciTech Connect

    Acken, J. M.; Goldstein, L. H.

    1980-01-01

    As digital integrated circuit size and complexity increases, the need for accurate and efficient computer simulation increases. Logic simulators such as SALOGS (SAndia LOGic Simulator), which utilize transition states in addition to the normal stable states, provide more accurate analysis than is possible with traditional logic simulators. Furthermore, the computational complexity of this analysis is far lower than that of circuit simulation such as SPICE. An eight-value logic simulation environment allows the use of accurate delay models that incorporate both element response and transition times. Thus, timing simulation with an accuracy approaching that of circuit simulation can be accomplished with an efficiency comparable to that of logic simulation. 4 figures.

  8. Modelling ecological interaction despite object-oriented modularity 

    E-print Network

    Derry, Julian F

    1998-01-01

    Ecological modellers may be deterred from using object-oriented programming languages by reports of the inherent rigidity of the object-oriented formulation, giving rise to a poor representation of biotic interaction. ...

  9. INVASIVE SPECIES: PREDICTING GEOGRAPHIC DISTRIBUTIONS USING ECOLOGICAL NICHE MODELING

    EPA Science Inventory

    Present approaches to species invasions are reactive in nature. This scenario results in management that perpetually lags behind the most recent invasion and makes control much more difficult. In contrast, spatially explicit ecological niche modeling provides an effective solut...

  10. EXPLANATORY MODELS FOR ECOLOGICAL RESPONSE SURFACES

    EPA Science Inventory

    It is often spatial patterns in environmental and ecological variables that arouse interest and demand explanation. or environmental response variables, the causal influences of interacting environmental factors produce the patterns of interest. cological response variables by de...

  11. A Parallel Structured Ecological Model for High End Shared Memory Computers

    Microsoft Academic Search

    Dali Wang; Michael W. Berry; Louis J. Gross

    This paper presents a new approach to parallelize spatially-explicit structured ecological models. Previous investigations\\u000a have mainly focused on the use of spatial decomposition for parallelization of these models. Here, we exploit the partitioning\\u000a of species’ age structures (or layers) as part of an integrated ecosystem simulation on a high-end shared memory computer\\u000a using OpenMP. As an example, we use a

  12. Including Overweight or Obese Students in Physical Education: A Social Ecological Constraint Model

    ERIC Educational Resources Information Center

    Li, Weidong; Rukavina, Paul

    2012-01-01

    In this review, we propose a social ecological constraint model to study inclusion of overweight or obese students in physical education by integrating key concepts and assumptions from ecological constraint theory in motor development and social ecological models in health promotion and behavior. The social ecological constraint model proposes…

  13. Boechera, a model system for ecological genomics

    PubMed Central

    Rushworth, Catherine A.; Song, Bao-Hua; Lee, Cheng-Ruei; Mitchell-Olds, Thomas

    2011-01-01

    The selection and development of a study system for evolutionary and ecological functional genomics (EEFG) depends on a variety of factors. Here we present the genus Boechera as an exemplary system with which to address ecological and evolutionary questions. Our focus on Boechera is based on several characteristics: 1) native populations in undisturbed habitats where current environments reflect historical conditions over several thousand years; 2) functional genomics benefitting from its close relationship to Arabidopsis thaliana; 3) inbreeding tolerance enabling development of recombinant inbred lines, near-isogenic lines, and positional cloning; 4) interspecific crosses permitting mapping for genetic analysis of speciation; 5) apomixis (asexual reproduction by seeds) in a genetically tractable diploid; and 6) broad geographic distribution in North America, permitting ecological genetics for a large research community. These characteristics, along with the current sequencing of three Boechera species by the Joint Genome Institute, position Boechera as a rapidly advancing system for EEFG studies. PMID:22059452

  14. Diffusion Approximations for Ecological Models P.K. Pollett

    E-print Network

    Pollett, Phil

    Diffusion Approximations for Ecological Models P.K. Pollett Department of Mathematics, The University of Queensland, Queensland 4072 Australia (pkp@maths.uq.edu.au) Abstract: Diffusion models to inaccurate predictions of critical quantities such as persistence times. This paper examines diffusion models

  15. Ecological Interface Design in the Nuclear Domain: An Empirical Evaluation of Ecological Displays for the Secondary Subsystems of a Boiling Water Reactor Plant Simulator

    Microsoft Academic Search

    Nathan Lau; Greg A. Jamieson; Catherine M. Burns

    2008-01-01

    Laboratory studies have shown that ecological interfaces can enhance operator performance in process control. However, limited verification and validation studies in representative settings are impeding the adoption of the Ecological Interface Design (EID) framework in the nuclear domain. A companion article presents an application of EID to the secondary side of a boiling water reactor plant simulator, demonstrating that the

  16. VARIOGRAPHY AND CONDITIONAL SEQUENTIAL SIMULATION: NEW TOOLS FOR ECOLOGICAL MONITORING

    EPA Science Inventory

    The Superfund reauthorization Act requires an ecological impact statement as part of each site assessment. his is difficult because of the hierarchical multiple dimensionality of ecosystems and becaus of the limited time and resources for the site's monitoring and evaluation. he ...

  17. State of the art of ecological modelling in limnology

    Microsoft Academic Search

    Sven Erik Jørgensen

    1995-01-01

    An overview of modelling in limnology is given by presentation of core problems and milestones of ecological modelling. The history of modelling can be presented by five generations of models, from Lotka-Volterra and Streeter-Phelps to the structural dynamic models of today. The three major problems of modelling in the 1970s are discussed. They are: how do we build a reliable

  18. Large-scale ecological simulations are natural candidates for distributed discrete event simulation. In optimistic sim-

    E-print Network

    Oregon, University of

    turning to individual-based models [1][3]. Rather than summarizing average case behavior with sys- tems of differential equations, an individual based model uses a representation of each individual plant or animal that represent cells. A straightforward approach to distributed simulation is to partition the physical territory

  19. Meeting in Turkey: WASP Transport Modeling and WASP Ecological Modeling

    EPA Science Inventory

    A combination of lectures, demonstrations, and hands-on excercises will be used to introduce pollutant transport modeling with the U.S. EPA's general water quality model, WASP (Water Quality Analysis Simulation Program). WASP features include a user-friendly Windows-based interfa...

  20. Distribution of phytoplankton functional types in high-nitrate, low-chlorophyll waters in a new diagnostic ecological indicator model

    NASA Astrophysics Data System (ADS)

    Palacz, A. P.; St. John, M. A.; Brewin, R. J. W.; Hirata, T.; Gregg, W. W.

    2013-11-01

    Modeling and monitoring plankton functional types (PFTs) is challenged by the insufficient amount of field measurements of ground truths in both plankton models and bio-optical algorithms. In this study, we combine remote sensing data and a dynamic plankton model to simulate an ecologically sound spatial and temporal distribution of phyto-PFTs. We apply an innovative ecological indicator approach to modeling PFTs and focus on resolving the question of diatom-coccolithophore coexistence in the subpolar high-nitrate and low-chlorophyll regions. We choose an artificial neural network as our modeling framework because it has the potential to interpret complex nonlinear interactions governing complex adaptive systems, of which marine ecosystems are a prime example. Using ecological indicators that fulfill the criteria of measurability, sensitivity and specificity, we demonstrate that our diagnostic model correctly interprets some basic ecological rules similar to ones emerging from dynamic models. Our time series highlight a dynamic phyto-PFT community composition in all high-latitude areas and indicate seasonal coexistence of diatoms and coccolithophores. This observation, though consistent with in situ and remote sensing measurements, has so far not been captured by state-of-the-art dynamic models, which struggle to resolve this "paradox of the plankton". We conclude that an ecological indicator approach is useful for ecological modeling of phytoplankton and potentially higher trophic levels. Finally, we speculate that it could serve as a powerful tool in advancing ecosystem-based management of marine resources.

  1. Distribution of phytoplankton functional types in high-nitrate low-chlorophyll waters in a new diagnostic ecological indicator model

    NASA Astrophysics Data System (ADS)

    Palacz, A. P.; St. John, M. A.; Brewin, R. J. W.; Hirata, T.; Gregg, W. W.

    2013-05-01

    Modeling and monitoring plankton functional types (PFTs) is challenged by insufficient amount of field measurements to ground-truth both plankton models and bio-optical algorithms. In this study, we combine remote sensing data and a dynamic plankton model to simulate an ecologically-sound spatial and temporal distribution of phyto-PFTs. We apply an innovative ecological indicator approach to modeling PFTs, and focus on resolving the question of diatom-coccolithophore co-existence in the subpolar high-nitrate and low-chlorophyll regions. We choose an artificial neural network as our modeling framework because it has the potential to interpret complex nonlinear interactions governing complex adaptive systems, of which marine ecosystems are a prime example. Using ecological indicators that fulfill the criteria of measurability, sensitivity and specificity, we demonstrate that our diagnostic model correctly interprets some basic ecological rules similar to ones emerging from dynamic models. Our time series highlight a dynamic phyto-PFT community composition in all high latitude areas, and indicate seasonal co-existence of diatoms and coccolithophores. This observation, though consistent with in situ and remote sensing measurements, was so far not captured by state-of-the-art dynamic models which struggle to resolve this "paradox of the plankton". We conclude that an ecological indicator approach is useful for ecological modeling of phytoplankton and potentially higher trophic levels. Finally, we speculate that it could serve as a powerful tool in advancing ecosystem-based management of marine resources.

  2. PLACE PRIORITIZATION FOR BIODIVERSITY REPRESENTATION USING SPECIES' ECOLOGICAL NICHE MODELING

    Microsoft Academic Search

    Víctor Sánchez-Cordero; Verónica Cirelli; Mariana Munguía; Sahotra Sarkar

    2005-01-01

    Place prioritization for biodiversity representation is essential for conservation planning, particularly in megadiverse countries where high deforestation threatens biodiversity. Given the collecting biases and uneven sampling of biological inventories, there is a need to develop robust models of species' distributions. By modeling species' ecological niches using point occurrence data and digitized environmental feature maps, we can predict potential and extant

  3. Ecological Modelling 177 (2004) 129142 Dynamic trophic cascade

    E-print Network

    Vermont, University of

    2004-01-01

    Ecological Modelling 177 (2004) 129­142 Dynamic trophic cascade Robert A. Herendeen Illinois-function) perturbations on food chains [Ecol. Model. 171 (2004) 21]. The method allows explicit variation-down cascade effects are hard to detect. © 2004 Elsevier B.V. All rights reserved. Keywords: Trophic cascade

  4. ELSEVIER EcologicalModelling95 (1997)95-111 Using machine learning techniques in the construction of models.

    E-print Network

    Dzeroski, Saso

    1997-01-01

    ELSEVIER EcologicalModelling95 (1997)95-111 E(OL061(I monBun6 Using machine learning techniques the acquisition of ecological knowledge, i.e., automate the construction of ecological models. This paper analysis in several ecological domains. These include the biological classification of British rivers based

  5. Simulation of a fire-sensitive ecological threshold: a case study of Ashe juniper on the Edwards Plateau of Texas, USA

    Microsoft Academic Search

    Samuel D. Fuhlendorf; Fred E. Smeins; William E. Grant

    1996-01-01

    A model was developed to represent the establishment of a fire-sensitive woody species from seeds and subsequent survival and growth through five size classes. Simulations accurately represent structural changes associated with increased density and cover of the fire-sensitive Ashe juniper (Juniperus ashei, Buckholz) and provide substantial evidence for multiple steady states and ecological thresholds. Without fire, Ashe juniper increases and

  6. Numerical wind speed simulation model

    SciTech Connect

    Ramsdell, J.V.; Athey, G.F.; Ballinger, M.Y.

    1981-09-01

    A relatively simple stochastic model for simulating wind speed time series that can be used as an alternative to time series from representative locations is described in this report. The model incorporates systematic seasonal variation of the mean wind, its standard deviation, and the correlation speeds. It also incorporates systematic diurnal variation of the mean speed and standard deviation. To demonstrate the model capabilities, simulations were made using model parameters derived from data collected at the Hanford Meteorology Station, and results of analysis of simulated and actual data were compared.

  7. SIMULATION OF ECOLOGICALLY CONSCIOUS CHEMICAL PROCESSES: FUGITIVE EMISSIONS VERSUS OPERATING CONDITIONS: JOURNAL ARTICLE

    EPA Science Inventory

    NRMRL-CIN-1531A Mata, T.M., Smith*, R.L., Young*, D., and Costa, C.A.V. "Simulation of Ecologically Conscious Chemical Processes: Fugitive Emissions versus Operating Conditions." Paper published in: CHEMPOR' 2001, 8th International Chemical Engineering Conference, Aveiro, Portu...

  8. Ecology, 00(0), 0000, pp. 000000 0000 by the Ecological Society of America

    E-print Network

    Turner, Monica G.

    ecology; simulation modeling; sustain- ability. Why are starfish like an atomic bomb? The answer, according to the co-authors of Complexity in landscape ecology, is that like the chain reaction of atomic

  9. Ecological prediction with nonlinear multivariate time-frequency functional data models

    USGS Publications Warehouse

    Yang, Wen-Hsi; Wikle, Christopher K.; Holan, Scott H.; Wildhaber, Mark L.

    2013-01-01

    Time-frequency analysis has become a fundamental component of many scientific inquiries. Due to improvements in technology, the amount of high-frequency signals that are collected for ecological and other scientific processes is increasing at a dramatic rate. In order to facilitate the use of these data in ecological prediction, we introduce a class of nonlinear multivariate time-frequency functional models that can identify important features of each signal as well as the interaction of signals corresponding to the response variable of interest. Our methodology is of independent interest and utilizes stochastic search variable selection to improve model selection and performs model averaging to enhance prediction. We illustrate the effectiveness of our approach through simulation and by application to predicting spawning success of shovelnose sturgeon in the Lower Missouri River.

  10. Ecological Modelling 145 (2001) 111121 Assessing habitat-suitability models with a virtual species

    E-print Network

    Alvarez, Nadir

    2001-01-01

    Ecological Modelling 145 (2001) 111­121 Assessing habitat-suitability models with a virtual species A.H. Hirzel *, V. Helfer, F. Metral Laboratory for Conser6ation Biology, Institute of Ecology, Uni6 May 2001; accepted 22 May 2001 Abstract This paper compares two habitat-suitability assessing methods

  11. Ecological Modelling 138 (2001) 321330 Habitat suitability modelling for red deer (Cer6us elaphus

    E-print Network

    Dzeroski, Saso

    2001-01-01

    Ecological Modelling 138 (2001) 321­330 Habitat suitability modelling for red deer (Cer6us elaphus and assess the potential habitats of a population of red deer in South-central Slovenia. Using existing data on the deer population spatial distribution and size, as well as data on the landscape and ecological

  12. Model Organisms Retain an “Ecological Memory” of Complex Ecologically Relevant Environmental Variation

    PubMed Central

    Beer, Karlyn D.; Wurtmann, Elisabeth J.; Pinel, Nicolás

    2014-01-01

    Although tractable model organisms are essential to characterize the molecular mechanisms of evolution and adaptation, the ecological relevance of their behavior is not always clear because certain traits are easily lost during long-term laboratory culturing. Here, we demonstrate that despite their long tenure in the laboratory, model organisms retain “ecological memory” of complex environmental changes. We have discovered that Halobacterium salinarum NRC-1, a halophilic archaeon that dominates microbial communities in a dynamically changing hypersaline environment, simultaneously optimizes fitness to total salinity, NaCl concentration, and the [K]/[Mg] ratio. Despite being maintained under controlled conditions over the last 50 years, peaks in the three-dimensional fitness landscape occur in salinity and ionic compositions that are not replicated in laboratory culturing but are routinely observed in the natural hypersaline environment of this organism. Intriguingly, adaptation to variations in ion composition was associated with differential regulation of anaerobic metabolism genes, suggesting an intertwined relationship between responses to oxygen and salinity. Our results suggest that the ecological memory of complex environmental variations is imprinted in the networks for coordinating multiple cellular processes. These coordination networks are also essential for dealing with changes in other physicochemically linked factors present during routine laboratory culturing and, hence, retained in model organisms. PMID:24413600

  13. QUANTITATIVE ECOLOGY A Spatial, Markovian Model of Rangeland Grasshopper

    E-print Network

    Latchininsky, Alexandre

    QUANTITATIVE ECOLOGY A Spatial, Markovian Model of Rangeland Grasshopper (Orthoptera: Acrididae of Wyoming are likely to support multiyear infestations of rangeland grasshoppers. Across the state, 91 to the next. Considering only the land that has ever been infested by grasshoppers, 55% of this area was found

  14. Application of an Ecological Model for the Cibolo Creek Watershed

    Microsoft Academic Search

    David Price; Terry McLendon; Cade Coldren

    BACKGROUND: The U.S. Army Engineer District, Fort Worth (CESWF) is involved in demon- strating the utility of an ecological model in the performance and interpretation of a comprehensive General Investigations (GI) study of the Cibolo Creek watershed upstream of Interstate 10 near San Antonio, Texas. Partners to the District in this project are the Natural Resources Conservation Service (NRCS), U.S.

  15. ASSESSMENT OF SPATIAL AUTOCORRELATION IN EMPIRICAL MODELS IN ECOLOGY

    EPA Science Inventory

    Statistically assessing ecological models is inherently difficult because data are autocorrelated and this autocorrelation varies in an unknown fashion. At a simple level, the linking of a single species to a habitat type is a straightforward analysis. With some investigation int...

  16. A Novel Integrated Ecological Model for the study of Sustainability

    EPA Science Inventory

    In recent years, there has been a growing interest among various sections of the society in the study of sustainability. Recently, a generalized mathematical model depicting a combined economic-ecological-social system has been proposed to help in the formal study of sustainabili...

  17. A Model of Practice in Special Education: Dynamic Ecological Analysis

    ERIC Educational Resources Information Center

    Hannant, Barbara; Lim, Eng Leong; McAllum, Ruth

    2010-01-01

    Dynamic Ecological Analysis (DEA) is a model of practice which increases a teams' efficacy by enabling the development of more effective interventions through collaboration and collective reflection. This process has proved to be useful in: a) clarifying thinking and problem-solving, b) transferring knowledge and thinking to significant parties,…

  18. Silene as a model system in ecology and evolution

    Microsoft Academic Search

    G. Bernasconi; J. Antonovics; A. Biere; D. Charlesworth; L. F. Delph; D. Filatov; T. Giraud; M. E. Hood; G. A. B. Marais; D. McCauley; J. R. Pannell; J. A. Shykoff; B. Vyskot; L. M. Wolfe; A. Widmer

    2009-01-01

    The genus Silene, studied by Darwin, Mendel and other early scientists, is re-emerging as a system for studying interrelated questions in ecology, evolution and developmental biology. These questions include sex chromosome evolution, epigenetic control of sex expression, genomic conflict and speciation. Its well-studied interactions with the pathogen Microbotryum has made Silene a model for the evolution and dynamics of disease

  19. The Quality of Home Environment in Brazil: An Ecological Model

    Microsoft Academic Search

    Ebenézer A. de Oliveira; Fernando C. Barros; Luciana D. da Silva Anselmi; Cesar A. Piccinini

    2006-01-01

    Based on Bronfenbrenner's (1999) ecological perspective, a longitudinal, prospective model of individual differences in the quality of home environment (Home Observation for Measurement of the Environment—HOME) was tested in a sample of 179 Brazilian children and their families. Perinatal measures of family socioeconomic status (SES) and child birth weight had direct effects on HOME at preschool age. As either family

  20. Predicting the geography of species' invasions via ecological niche modeling

    E-print Network

    Peterson, A. Townsend

    2003-12-01

    for invasion of the Pacific Northwest by Strix varia, an owl native to east- 428 Volume 78THE QUARTERLY REVIEW OF BIOLOGY Figure 3. Projections of Asian longhorned beetle (Anoplophora glabripennis) ecological niche models (developed on the species’s native...

  1. MODELING THE ECOLOGY OF THE WKIU BUG'S MAUNA KEA ENVIRONMENT

    E-print Network

    Businger, Steven

    MODELING THE ECOLOGY OF THE WKIU BUG'S MAUNA KEA ENVIRONMENT A THESIS SUBMITTED TO THE GRADUATE for providing me with a world of knowledge about the Wkiu Bug, and always being there with my questions about is to develop a better understating of Wkiu Bug distribution and population health, which are controlled

  2. book August 29, 2007 Ecological Models and Data in R

    E-print Network

    book August 29, 2007 Ecological Models and Data in R #12;book August 29, 2007 #12;book August 29;book August 29, 2007 iv ACKNOWLEDGMENTS Lots of people have helped me start and finish this book. I books is just what people do. And last but not least Aidan and especially Tara for their love, pa

  3. Development of stable isotope mixing models in ecology - Fremantle

    EPA Science Inventory

    More than 40 years ago, stable isotope analysis methods used in geochemistry began to be applied to ecological studies. One common application is using mathematical mixing models to sort out the proportional contributions of various sources to a mixture. Examples include contri...

  4. Development of stable isotope mixing models in ecology - Sydney

    EPA Science Inventory

    More than 40 years ago, stable isotope analysis methods used in geochemistry began to be applied to ecological studies. One common application is using mathematical mixing models to sort out the proportional contributions of various sources to a mixture. Examples include contri...

  5. Development of stable isotope mixing models in ecology - Dublin

    EPA Science Inventory

    More than 40 years ago, stable isotope analysis methods used in geochemistry began to be applied to ecological studies. One common application is using mathematical mixing models to sort out the proportional contributions of various sources to a mixture. Examples include contri...

  6. Development of stable isotope mixing models in ecology - Perth

    EPA Science Inventory

    More than 40 years ago, stable isotope analysis methods used in geochemistry began to be applied to ecological studies. One common application is using mathematical mixing models to sort out the proportional contributions of various sources to a mixture. Examples include contri...

  7. Automatic programming of simulation models

    NASA Technical Reports Server (NTRS)

    Schroer, Bernard J.; Tseng, Fan T.; Zhang, Shou X.; Dwan, Wen S.

    1988-01-01

    The objective of automatic programming is to improve the overall environment for describing the program. This improved environment is realized by a reduction in the amount of detail that the programmer needs to know and is exposed to. Furthermore, this improved environment is achieved by a specification language that is more natural to the user's problem domain and to the user's way of thinking and looking at the problem. The goal of this research is to apply the concepts of automatic programming (AP) to modeling discrete event simulation system. Specific emphasis is on the design and development of simulation tools to assist the modeler define or construct a model of the system and to then automatically write the corresponding simulation code in the target simulation language, GPSS/PC. A related goal is to evaluate the feasibility of various languages for constructing automatic programming simulation tools.

  8. Water quality simulation modeling and uncertainty analysis for risk assessment and decision making

    Microsoft Academic Search

    Kenneth H. Reckhow

    1994-01-01

    The usefulness of water quality simulation models for environmental management is explored with a focus on prediction uncertainty. Ecological risk and environmental analysis often involve scientific assessments that are highly uncertain. Still, environmental manage- ment decisions are being made, often with the support of a mathematical simulation model. In the area of pollutant transport and fate in surface waters, few

  9. Ecologic Niche Modeling of Blastomyces dermatitidis in Wisconsin

    PubMed Central

    Reed, Kurt D.; Meece, Jennifer K.; Archer, John R.; Peterson, A. Townsend

    2008-01-01

    Background Blastomycosis is a potentially fatal mycosis that is acquired by inhaling infectious spores of Blastomyces dermatitidis present in the environment. The ecology of this pathogen is poorly understood, in part because it has been extremely difficult to identify the niche(s) it occupies based on culture isolation of the organism from environmental samples. Methodology/Principal Findings We investigated the ecology of blastomycosis by performing maximum entropy modeling of exposure sites from 156 cases of human and canine blastomycosis to provide a regional-scale perspective of the geographic and ecologic distribution of B. dermatitidis in Wisconsin. Based on analysis with climatic, topographic, surface reflectance and other environmental variables, we predicted that ecologic conditions favorable for maintaining the fungus in nature occur predominantly within northern counties and counties along the western shoreline of Lake Michigan. Areas of highest predicted occurrence were often in proximity to waterways, especially in northcentral Wisconsin, where incidence of infection is highest. Ecologic conditions suitable for B. dermatitidis are present in urban and rural environments, and may differ at the extremes of distribution of the species in the state. Conclusions/Significance Our results provide a framework for a more informed search for specific environmental factors modulating B. dermatitidis occurrence and transmission and will be useful for improving public health awareness of relative exposure risks. PMID:18446224

  10. Chain models in computer simulation

    Microsoft Academic Search

    R. Egli; N. F. Stewart

    2004-01-01

    This paper presents an extension of a previously-described framework for the specification and manipulation of models of systems. The original framework and its extension include a convenient application programming interface (API), and this paper describes examples of the use of this API in the context of graphical simulation. These examples include the simulation of objects whose definition involves torques, and

  11. A 2-D process-based model for suspended sediment dynamics: a first step towards ecological modeling

    NASA Astrophysics Data System (ADS)

    Achete, F. M.; van der Wegen, M.; Roelvink, D.; Jaffe, B.

    2015-06-01

    In estuaries suspended sediment concentration (SSC) is one of the most important contributors to turbidity, which influences habitat conditions and ecological functions of the system. Sediment dynamics differs depending on sediment supply and hydrodynamic forcing conditions that vary over space and over time. A robust sediment transport model is a first step in developing a chain of models enabling simulations of contaminants, phytoplankton and habitat conditions. This works aims to determine turbidity levels in the complex-geometry delta of the San Francisco estuary using a process-based approach (Delft3D Flexible Mesh software). Our approach includes a detailed calibration against measured SSC levels, a sensitivity analysis on model parameters and the determination of a yearly sediment budget as well as an assessment of model results in terms of turbidity levels for a single year, water year (WY) 2011. Model results show that our process-based approach is a valuable tool in assessing sediment dynamics and their related ecological parameters over a range of spatial and temporal scales. The model may act as the base model for a chain of ecological models assessing the impact of climate change and management scenarios. Here we present a modeling approach that, with limited data, produces reliable predictions and can be useful for estuaries without a large amount of processes data.

  12. SIMULATION MODELLING OF BUSINESS PROCESSES

    Microsoft Academic Search

    Ray J. Paul; Vlatka Hlupic; George M. Giaglis

    Increasingly, organisations need to adapt to new conditions and competitive pressures. Various change management approaches such as business process re- engineering have been developed to meet this perceived need. This paper investigates the potential of simulation modelling for modelling business processes. After a discussion on business processes related issues, an overview of business process modelling methods is presented. The usability

  13. Evolutionary and Ecological Genomics of Non-Model Plants

    PubMed Central

    Song, Bao-Hua; Mitchell-Olds, Thomas

    2011-01-01

    Dissecting evolutionary dynamics of ecologically important traits is a long-term challenge for biologists. Attempts to understand natural variation and molecular mechanisms have motivated a move from laboratory model systems to non-model systems in diverse natural environments. Next generation sequencing methods, along with an expansion of genomic resources and tools, have fostered new links between diverse disciplines, including molecular biology, evolution, and ecology, and genomics. Great progress has been made in a few non-model wild plants, such as Arabidopsis relatives, monkey flowers, and wild sunflowers. Until recently, the lack of comprehensive genomic information has limited evolutionary and ecological studies to larger QTL regions rather than single gene resolution, and has hindered recognition of general patterns of natural variation and local adaptation. Further efforts in accumulating genomic data and developing bioinformatic and biostatistical tools are now poised to move this field forward. Integrative national and international collaborations and research communities are needed to facilitate development in the field of evolutionary and ecological genomics. PMID:21394233

  14. Ecology.

    ERIC Educational Resources Information Center

    National Audubon Society, New York, NY.

    This set of teaching aids consists of nine Audubon Nature Bulletins, providing teachers and students with informational reading on various ecological topics. The bulletins have these titles: Schoolyard Laboratories, Owls and Predators, The Forest Community, Life in Freshwater Marshes, Camouflage in the Animal World, Life in the Desert, The…

  15. Progress in modeling and simulation.

    PubMed

    Kindler, E

    1998-01-01

    For the modeling of systems, the computers are more and more used while the other "media" (including the human intellect) carrying the models are abandoned. For the modeling of knowledges, i.e. of more or less general concepts (possibly used to model systems composed of instances of such concepts), the object-oriented programming is nowadays widely used. For the modeling of processes existing and developing in the time, computer simulation is used, the results of which are often presented by means of animation (graphical pictures moving and changing in time). Unfortunately, the object-oriented programming tools are commonly not designed to be of a great use for simulation while the programming tools for simulation do not enable their users to apply the advantages of the object-oriented programming. Nevertheless, there are exclusions enabling to use general concepts represented at a computer, for constructing simulation models and for their easy modification. They are described in the present paper, together with true definitions of modeling, simulation and object-oriented programming (including cases that do not satisfy the definitions but are dangerous to introduce misunderstanding), an outline of their applications and of their further development. In relation to the fact that computing systems are being introduced to be control components into a large spectrum of (technological, social and biological) systems, the attention is oriented to models of systems containing modeling components. PMID:10803299

  16. Ecological Modelling 188 (2005) 358373 A model of digestion modulation in grasshoppers

    E-print Network

    Logan, David

    2005-01-01

    Ecological Modelling 188 (2005) 358­373 A model of digestion modulation in grasshoppers William structures (crop, midgut, and hemolymph system) that reasonably reflect available results for grasshoppers.V. Keywords: Absorption-limited; Digestion; Foraging; Ecophysiology; Grasshoppers; Insects Corresponding

  17. Advanced Space Shuttle simulation model

    NASA Technical Reports Server (NTRS)

    Tatom, F. B.; Smith, S. R.

    1982-01-01

    A non-recursive model (based on von Karman spectra) for atmospheric turbulence along the flight path of the shuttle orbiter was developed. It provides for simulation of instantaneous vertical and horizontal gusts at the vehicle center-of-gravity, and also for simulation of instantaneous gusts gradients. Based on this model the time series for both gusts and gust gradients were generated and stored on a series of magnetic tapes, entitled Shuttle Simulation Turbulence Tapes (SSTT). The time series are designed to represent atmospheric turbulence from ground level to an altitude of 120,000 meters. A description of the turbulence generation procedure is provided. The results of validating the simulated turbulence are described. Conclusions and recommendations are presented. One-dimensional von Karman spectra are tabulated, while a discussion of the minimum frequency simulated is provided. The results of spectral and statistical analyses of the SSTT are presented.

  18. mizer: an R package for multispecies, trait-based and community size spectrum ecological modelling

    PubMed Central

    Scott, Finlay; Blanchard, Julia L; Andersen, Ken H

    2014-01-01

    Size spectrum ecological models are representations of a community of individuals which grow and change trophic level. A key emergent feature of these models is the size spectrum; the total abundance of all individuals that scales negatively with size. The models we focus on are designed to capture fish community dynamics useful for assessing the community impacts of fishing.We present mizer, an R package for implementing dynamic size spectrum ecological models of an entire aquatic community subject to fishing. Multiple fishing gears can be defined and fishing mortality can change through time making it possible to simulate a range of exploitation strategies and management options.mizer implements three versions of the size spectrum modelling framework: the community model, where individuals are only characterized by their size; the trait-based model, where individuals are further characterized by their asymptotic size; and the multispecies model where additional trait differences are resolved.A range of plot, community indicator and summary methods are available to inspect the results of the simulations. PMID:25866613

  19. ECOLOGICAL MODEL TESTING: VERIFICATION, VALIDATION OR NEITHER?

    EPA Science Inventory

    Consider the need to make a management decision about a declining animal population. Two models are available to help. Before a decision is made based on model results, the astute manager or policy maker may ask, "Do the models work?" Or, "Have the models been verified or validat...

  20. Development of a zoning-based environmental-ecological-coupled model for lakes: a case study of Baiyangdian Lake in North China

    NASA Astrophysics Data System (ADS)

    Zhao, Y. W.; Xu, M. J.; Xu, F.; Wu, S. R.; Yin, X. A.

    2014-02-01

    Environmental/ecological models are widely used for lake management as they provide a means to understand physical, chemical and biological processes in highly complex ecosystems. Most research focused on the development of environmental (water quality) and ecological models, separately. Limited studies were developed to couple the two models, and in these limited coupled models a lake was regarded as a whole for analysis (i.e., considering the lake to be one well-mixed box), which was appropriate for small-scale lakes and was not sufficient to capture spatial variations within middle-scale or large-scale lakes. In response to this problem, this paper seeks to establish a zoning-based environmental-ecological-coupled model for a lake. The hierarchical cluster analysis (HCA) was adopted to determine the number of zones for a lake based on the analysis of hydrological, water quality and ecological data. MIKE21 model was used to construct two-dimensional hydrodynamics and water quality simulations. STELLA software was used to create a lake ecological model which can simulate the spatial variations of ecological condition based on flow field distribution results generated by MIKE21. The Baiyangdian Lake, the largest freshwater lake in Northern China, was adopted as the study case. The results showed that the new model was promising to predict the spatial variation trends of ecological condition in response to the changes of water quantity and water quality for lakes, and could provide a great convenience for lake management.

  1. Bjt Modeling for Circuit Simulation

    Microsoft Academic Search

    Clement Keung Szeto

    1995-01-01

    Physical models for transport mechanisms important in bipolar transistors are developed, implemented in SPICE3 for DC, AC, and transient analyses, and assessed with numerical device simulations. The analytical model of quasi-saturation, or base -push-out, is derived for all current levels. Deficiencies in previous quasi-saturation models are revealed and overcome. The quasi-saturation model is based on a derivation of the current-induced-base

  2. Model Predictive Control for Automobile Ecological Driving Using Traffic Signal Information

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Daisuke; Kamal, M. A. S.; Mukai, Masakazu; Kawabe, Taketoshi

    This paper presents development of a control system for ecological driving of an automobile. Prediction using traffic signal information is considered to improve the fuel economy. It is assumed that the automobile receives traffic signal information from Intelligent Transportation Systems (ITS). Model predictive control is used to calculate optimal vehicle control inputs using traffic signal information. The performance of the proposed method was analyzed through computer simulation results. It was observed that fuel economy was improved compared with driving of a typical human driving model.

  3. Serpentine: The Evolution and Ecology of a Model System edited by Susan Harrison and Nishanta Rajakaruna

    E-print Network

    Rajakaruna, Nishanta

    Serpentine: The Evolution and Ecology of a Model System edited by Susan Harrison and Nishanta Rajakaruna Serpentine: The Evolution and Ecology of a Model System by Susan Harrison; Nishanta Rajakaruna Ecology & Management, Swedish University of Agricultural Sciences, Umeå, Sweden Serpentine: The Evolution

  4. A CONCEPTUAL MODEL FOR MULTI-SCALAR ASSESSMENTS OF ESTUARINE ECOLOGICAL INTEGRITY

    EPA Science Inventory

    A conceptual model was developed that relates an estuarine system's anthropogenic inputs to it's ecological integrity. Ecological integrity is operationally defined as an emergent property of an ecosystem that exists when the structural components are complete and the functional ...

  5. TEMPEST: a Fast Spatially Explicit Model of Ecological Dynamics on Parallel Machines

    E-print Network

    Maniatty, William A.

    of ecological processes is of prime importance in evolutionary biology and environmental sciencesTEMPEST: a Fast Spatially Explicit Model of Ecological Dynamics on Parallel Machines Bill Maniatty Tom Caraco Boleslaw Szymanski \\Lambda Computer Science Department Department of Biological Sciences

  6. Eco-genetic model to explore fishing-induced ecological and evolutionary effects on growth and maturation schedules

    PubMed Central

    Wang, Hui-Yu; Höök, Tomas O

    2009-01-01

    Eco-genetic individual-based models involve tracking the ecological dynamics of simulated individual organisms that are in part characterized by heritable parameters. We developed an eco-genetic individual-based model to explore ecological and evolutionary interactions of fish growth and maturation schedules. Our model is flexible and allows for exploration of the effects of heritable growth rates (based on von Bertalanffy and biphasic growth patterns), heritable maturation schedules (based on maturation reaction norm concepts), or both on individual- and population-level traits. In baseline simulations with rather simple ecological trade-offs and over a relatively short time period (<200 simulation years), simulated male and female fish evolve differential genetic growth and maturation. Further, resulting patterns of genetically determined growth and maturation are influenced by mortality rate and density-dependent processes, and maturation and growth parameters interact to mediate the evolution of one another. Subsequent to baseline simulations, we conducted experimental simulations to mimic fisheries harvest with two size-limits (targeting large or small fish), an array of fishing mortality rates, and assuming a deterministic or stochastic environment. Our results suggest that fishing with either size-limit may induce considerable changes in life-history trait expression (maturation schedules and growth rates), recruitment, and population abundance and structure. However, targeting large fish would cause more adverse genetic effects and may lead to a population less resilient to environmental stochasticity. PMID:25567890

  7. System dynamic modelling to assess economic viability and risk trade-offs for ecological restoration in South Africa.

    PubMed

    Crookes, D J; Blignaut, J N; de Wit, M P; Esler, K J; Le Maitre, D C; Milton, S J; Mitchell, S A; Cloete, J; de Abreu, P; Fourie nee Vlok, H; Gull, K; Marx, D; Mugido, W; Ndhlovu, T; Nowell, M; Pauw, M; Rebelo, A

    2013-05-15

    Can markets assist by providing support for ecological restoration, and if so, under what conditions? The first step in addressing this question is to develop a consistent methodology for economic evaluation of ecological restoration projects. A risk analysis process was followed in which a system dynamics model was constructed for eight diverse case study sites where ecological restoration is currently being pursued. Restoration costs vary across each of these sites, as do the benefits associated with restored ecosystem functioning. The system dynamics model simulates the ecological, hydrological and economic benefits of ecological restoration and informs a portfolio mapping exercise where payoffs are matched against the likelihood of success of a project, as well as a number of other factors (such as project costs and risk measures). This is the first known application that couples ecological restoration with system dynamics and portfolio mapping. The results suggest an approach that is able to move beyond traditional indicators of project success, since the effect of discounting is virtually eliminated. We conclude that systems dynamic modelling with portfolio mapping can guide decisions on when markets for restoration activities may be feasible. PMID:23524327

  8. Sticklebacks as model hosts in ecological and evolutionary parasitology.

    PubMed

    Barber, Iain

    2013-11-01

    The three-spined stickleback is a small teleost fish, native to coastal regions of the Northern Hemisphere, which has emerged as a key model organism in evolutionary biology and ecology. Sticklebacks possess a well-documented and experimentally amenable parasite fauna, and are well suited to both laboratory and field parasitological investigation. As a consequence, sticklebacks have been extensively used as model hosts in studies of host-parasite interactions, and these studies have provided considerable insight into the roles of parasites in ecology and evolutionary biology. In this review, I discuss key advances in our understanding of host-parasite interactions that have arisen from studies involving stickleback hosts, highlight areas of current research activity, and identify potentially promising areas for future research. PMID:24145060

  9. A J-MADeM agent-based social simulation to model urban mobility

    E-print Network

    Grimaldo, Francisco

    Chapter 1 A J-MADeM agent-based social simulation to model urban mobility Francisco Grimaldo1 transportation, will soon become unsustainable unless there is a change of citizens' minds and transport policies-based social simulation approach to tackle this kind of social-ecological systems. The Jason Multi-modal Agent

  10. ODEs Course Project: Investigating Nonlinear Ecological Models

    E-print Network

    Slastikov, Valeriy V.

    of interaction between species: cooperation, competition, predator- prey, e.t.c. In this project you will study basic models of predator-prey interaction and competing species interaction. Predator-Prey. The predator-prey. The interaction terms measure the efficiency of predator in converting food into more births (bxy), and the rate

  11. Modeling Molecular Dynamics from Simulations

    SciTech Connect

    Hinrichs, Nina Singhal (University of Chicago) [University of Chicago

    2009-01-28

    Many important processes in biology occur at the molecular scale. A detailed understanding of these processes can lead to significant advances in the medical and life sciences. For example, many diseases are caused by protein aggregation or misfolding. One approach to studying these systems is to use physically-based computational simulations to model the interactions and movement of the molecules. While molecular simulations are computationally expensive, it is now possible to simulate many independent molecular dynamics trajectories in a parallel fashion by using super- or distributed- computing methods such as Folding@Home or Blue Gene. The analysis of these large, high-dimensional data sets presents new computational challenges. In this seminar, I will discuss a novel approach to analyzing large ensembles of molecular dynamics trajectories to generate a compact model of the dynamics. This model groups conformations into discrete states and describes the dynamics as Markovian, or history-independent, transitions between the states. I will discuss why the Markovian state model (MSM) is suitable for macromolecular dynamics, and how it can be used to answer many interesting and relevant questions about the molecular system. I will also discuss many of the computational and statistical challenges in building such a model, such as how to appropriately cluster conformations, determine the statistical reliability, and efficiently design new simulations.

  12. Rapidly developing functional genomics in ecological model systems via 454 transcriptome sequencing

    E-print Network

    Wheat, Christopher

    Rapidly developing functional genomics in ecological model systems via 454 transcriptome sequencing Ó Springer Science+Business Media B.V. 2008 Abstract Next generation sequencing technology affords new opportunities in ecological genetics. This paper addresses how an ecological genetics research

  13. Automatic programming of simulation models

    NASA Technical Reports Server (NTRS)

    Schroer, Bernard J.; Tseng, Fan T.; Zhang, Shou X.; Dwan, Wen S.

    1990-01-01

    The concepts of software engineering were used to improve the simulation modeling environment. Emphasis was placed on the application of an element of rapid prototyping, or automatic programming, to assist the modeler define the problem specification. Then, once the problem specification has been defined, an automatic code generator is used to write the simulation code. The following two domains were selected for evaluating the concepts of software engineering for discrete event simulation: manufacturing domain and a spacecraft countdown network sequence. The specific tasks were to: (1) define the software requirements for a graphical user interface to the Automatic Manufacturing Programming System (AMPS) system; (2) develop a graphical user interface for AMPS; and (3) compare the AMPS graphical interface with the AMPS interactive user interface.

  14. Controlling chaos in ecology: from deterministic to individual-based models.

    PubMed

    Solé, R V; Gamarra, J G; Ginovart, M; López, D

    1999-11-01

    The possibility of chaos control in biological systems has been stimulated by recent advances in the study of heart and brain tissue dynamics. More recently, some authors have conjectured that such a method might be applied to population dynamics and even play a nontrivial evolutionary role in ecology. In this paper we explore this idea by means of both mathematical and individual-based simulation models. Because of the intrinsic noise linked to individual behavior, controlling a noisy system becomes more difficult but, as shown here, it is a feasible task allowed to be experimentally tested. PMID:17879875

  15. Economic Analysis. Computer Simulation Models.

    ERIC Educational Resources Information Center

    Sterling Inst., Washington, DC. Educational Technology Center.

    A multimedia course in economic analysis was developed and used in conjunction with the United States Naval Academy. (See ED 043 790 and ED 043 791 for final reports of the project evaluation and development model.) This volume of the text discusses the simulation of behavioral relationships among variable elements in an economy and presents…

  16. Photovoltaic array performance simulation models

    Microsoft Academic Search

    D. F. Menicucci

    1985-01-01

    The experience of the solar industry confirms that despite recent cost reductions the profitability of photovoltaic (PV) systems is often marginal and the configuration and sizing of a system is a critical problem for the design engineer. Construction and evaluation of experimental systems are expensive and seldom justifiable. A mathematical model or computer simulation program is a desirable alternative, provided

  17. Integrating Geographic Information Systems and Ecological Niche Modeling into Disease Ecology: A Case Study of Bacillus anthracis in the United States and Mexico

    Microsoft Academic Search

    Jason K. Blackburn

    \\u000a This chapter provides an overview of geographic information systems, spatial analysis and spatial statistics, and predictive\\u000a ecological niche modeling as they apply to disease ecology. I provide a conceptual model of the epidemiology and outbreak\\u000a ecology of anthrax and the landscape ecology of the pathogen Bacillus anthracis. I apply Anselin’s exploratory spatial data analysis process to these two components of

  18. Modeling abundance using N-mixture models: the importance of considering ecological mechanisms.

    PubMed

    Joseph, Liana N; Elkin, Ché; Martin, Tara G; Possinghami, Hugh P

    2009-04-01

    Predicting abundance across a species' distribution is useful for studies of ecology and biodiversity management. Modeling of survey data in relation to environmental variables can be a powerful method for extrapolating abundances across a species' distribution and, consequently, calculating total abundances and ultimately trends. Research in this area has demonstrated that models of abundance are often unstable and produce spurious estimates, and until recently our ability to remove detection error limited the development of accurate models. The N-mixture model accounts for detection and abundance simultaneously and has been a significant advance in abundance modeling. Case studies that have tested these new models have demonstrated success for some species, but doubt remains over the appropriateness of standard N-mixture models for many species. Here we develop the N-mixture model to accommodate zero-inflated data, a common occurrence in ecology, by employing zero-inflated count models. To our knowledge, this is the first application of this method to modeling count data. We use four variants of the N-mixture model (Poisson, zero-inflated Poisson, negative binomial, and zero-inflated negative binomial) to model abundance, occupancy (zero-inflated models only) and detection probability of six birds in South Australia. We assess models by their statistical fit and the ecological realism of the parameter estimates. Specifically, we assess the statistical fit with AIC and assess the ecological realism by comparing the parameter estimates with expected values derived from literature, ecological theory, and expert opinion. We demonstrate that, despite being frequently ranked the "best model" according to AIC, the negative binomial variants of the N-mixture often produce ecologically unrealistic parameter estimates. The zero-inflated Poisson variant is preferable to the negative binomial variants of the N-mixture, as it models an ecological mechanism rather than a statistical phenomenon and generates reasonable parameter estimates. Our results emphasize the need to include ecological reasoning when choosing appropriate models and highlight the dangers of modeling statistical properties of the data. We demonstrate that, to obtain ecologically realistic estimates of abundance, occupancy and detection probability, it is essential to understand the sources of variation in the data and then use this information to choose appropriate error distributions. PMID:19425427

  19. Simulation Model Driven Engineering for Manufacturing Cell

    E-print Network

    Paris-Sud XI, Université de

    Simulation Model Driven Engineering for Manufacturing Cell Hironori Hibino1 , Toshihiro Inukai2 Abstract. In our research, the simulation model driven engineering for manufacturing cell (SMDE on the simulation model and to extend the range of control applications and simulation applications using the PC

  20. Modeling and Simulation for Safeguards

    SciTech Connect

    Swinhoe, Martyn T. [Los Alamos National Laboratory

    2012-07-26

    The purpose of this talk is to give an overview of the role of modeling and simulation in Safeguards R&D and introduce you to (some of) the tools used. Some definitions are: (1) Modeling - the representation, often mathematical, of a process, concept, or operation of a system, often implemented by a computer program; (2) Simulation - the representation of the behavior or characteristics of one system through the use of another system, especially a computer program designed for the purpose; and (3) Safeguards - the timely detection of diversion of significant quantities of nuclear material. The role of modeling and simulation are: (1) Calculate amounts of material (plant modeling); (2) Calculate signatures of nuclear material etc. (source terms); and (3) Detector performance (radiation transport and detection). Plant modeling software (e.g. FACSIM) gives the flows and amount of material stored at all parts of the process. In safeguards this allow us to calculate the expected uncertainty of the mass and evaluate the expected MUF. We can determine the measurement accuracy required to achieve a certain performance.

  1. Multiscale Stochastic Simulation and Modeling

    SciTech Connect

    James Glimm; Xiaolin Li

    2006-01-10

    Acceleration driven instabilities of fluid mixing layers include the classical cases of Rayleigh-Taylor instability, driven by a steady acceleration and Richtmyer-Meshkov instability, driven by an impulsive acceleration. Our program starts with high resolution methods of numerical simulation of two (or more) distinct fluids, continues with analytic analysis of these solutions, and the derivation of averaged equations. A striking achievement has been the systematic agreement we obtained between simulation and experiment by using a high resolution numerical method and improved physical modeling, with surface tension. Our study is accompanies by analysis using stochastic modeling and averaged equations for the multiphase problem. We have quantified the error and uncertainty using statistical modeling methods.

  2. Assessment of Molecular Modeling & Simulation

    SciTech Connect

    None

    2002-01-03

    This report reviews the development and applications of molecular and materials modeling in Europe and Japan in comparison to those in the United States. Topics covered include computational quantum chemistry, molecular simulations by molecular dynamics and Monte Carlo methods, mesoscale modeling of material domains, molecular-structure/macroscale property correlations like QSARs and QSPRs, and related information technologies like informatics and special-purpose molecular-modeling computers. The panel's findings include the following: The United States leads this field in many scientific areas. However, Canada has particular strengths in DFT methods and homogeneous catalysis; Europe in heterogeneous catalysis, mesoscale, and materials modeling; and Japan in materials modeling and special-purpose computing. Major government-industry initiatives are underway in Europe and Japan, notably in multi-scale materials modeling and in development of chemistry-capable ab-initio molecular dynamics codes.

  3. Numerical models of salt marsh evolution: Ecological, geomorphic, and climatic factors

    USGS Publications Warehouse

    Fagherazzi, S.; Kirwan, M.L.; Mudd, S.M.; Guntenspergen, G.R.; Temmerman, S.; D'Alpaos, A.; Van De Koppel, J.; Rybczyk, J.M.; Reyes, E.; Craft, C.; Clough, J.

    2012-01-01

    Salt marshes are delicate landforms at the boundary between the sea and land. These ecosystems support a diverse biota that modifies the erosive characteristics of the substrate and mediates sediment transport processes. Here we present a broad overview of recent numerical models that quantify the formation and evolution of salt marshes under different physical and ecological drivers. In particular, we focus on the coupling between geomorphological and ecological processes and on how these feedbacks are included in predictive models of landform evolution. We describe in detail models that simulate fluxes of water, organic matter, and sediments in salt marshes. The interplay between biological and morphological processes often produces a distinct scarp between salt marshes and tidal flats. Numerical models can capture the dynamics of this boundary and the progradation or regression of the marsh in time. Tidal channels are also key features of the marsh landscape, flooding and draining the marsh platform and providing a source of sediments and nutrients to the marsh ecosystem. In recent years, several numerical models have been developed to describe the morphogenesis and long-term dynamics of salt marsh channels. Finally, salt marshes are highly sensitive to the effects of long-term climatic change. We therefore discuss in detail how numerical models have been used to determine salt marsh survival under different scenarios of sea level rise. Copyright 2012 by the American Geophysical Union.

  4. From actors to agents in socio-ecological systems models

    PubMed Central

    Rounsevell, M. D. A.; Robinson, D. T.; Murray-Rust, D.

    2012-01-01

    The ecosystem service concept has emphasized the role of people within socio-ecological systems (SESs). In this paper, we review and discuss alternative ways of representing people, their behaviour and decision-making processes in SES models using an agent-based modelling (ABM) approach. We also explore how ABM can be empirically grounded using information from social survey. The capacity for ABM to be generalized beyond case studies represents a crucial next step in modelling SESs, although this comes with considerable intellectual challenges. We propose the notion of human functional types, as an analogy of plant functional types, to support the expansion (scaling) of ABM to larger areas. The expansion of scope also implies the need to represent institutional agents in SES models in order to account for alternative governance structures and policy feedbacks. Further development in the coupling of human-environment systems would contribute considerably to better application and use of the ecosystem service concept. PMID:22144388

  5. Plant model generation for PLC simulation

    Microsoft Academic Search

    Hyeong-Tae Park; Jong-Geun Kwak; Gi-Nam Wang; Sang C. Park

    2010-01-01

    This paper reports an automated procedure for constructing a plant model for PLC simulation. Since PLC programs contain only the control logic without information on the plant model, it is necessary to build the corresponding plant model to perform the simulation. Conventionally, a plant model for PLC simulation has been constructed manually, which requires much effort and in-depth knowledge of

  6. Simulating spin models on GPU

    NASA Astrophysics Data System (ADS)

    Weigel, Martin

    2011-09-01

    Over the last couple of years it has been realized that the vast computational power of graphics processing units (GPUs) could be harvested for purposes other than the video game industry. This power, which at least nominally exceeds that of current CPUs by large factors, results from the relative simplicity of the GPU architectures as compared to CPUs, combined with a large number of parallel processing units on a single chip. To benefit from this setup for general computing purposes, the problems at hand need to be prepared in a way to profit from the inherent parallelism and hierarchical structure of memory accesses. In this contribution I discuss the performance potential for simulating spin models, such as the Ising model, on GPU as compared to conventional simulations on CPU.

  7. Ecological Modelling 164 (2003) 3347 A regional forest ecosystem carbon budget model: impacts

    E-print Network

    Song, Conghe

    2003-01-01

    Ecological Modelling 164 (2003) 33­47 A regional forest ecosystem carbon budget model: impacts investigated the impacts of landuse history and forest age structure on regional carbon fluxes for the forests, an individual-based forest ecosystem carbon flux model (IntCarb) at stand scale is developed. IntCarb combines

  8. Ecological Modelling 188 (2005) 253278 Modelling rain forest diversity: The role of competition

    E-print Network

    Maini, Philip K.

    2005-01-01

    Ecological Modelling 188 (2005) 253­278 Modelling rain forest diversity: The role of competition C model. Our analysis has general implications for all tropical rain forests in that it suggests; Rain forests; Seeding events 1. Introduction There has been much debate about the degree to which

  9. Integrating modelling architecture: a declarative framework for multi-paradigm, multi-scale ecological modelling

    Microsoft Academic Search

    Ferdinando Villa

    2001-01-01

    Multiple modelling paradigms are necessary to formulate crucial modelling problems in modern environmental science. Modelling paradigms help researchers to conceive, formulate and solve problems by providing semantic structures to organise their view of a system or process. An unusually large array of different paradigms is used in Ecology, reflecting the complexity and variety of the natural world. As a result

  10. Comparison of numerical simulations of reactive transport and chemostat-like models

    Microsoft Academic Search

    Ihab Haidar; Frédéric Gérard; Alain Rapaport

    2011-01-01

    The objective of the paper is to evaluate the ability of reactive transport models and their numerical implementations (such as MIN3P) to simulate simple microbial transformations in conditions of chemostat or gradostat models, that are popular in microbial ecology and waste treatment ecosystems. To make this comparison, we first consider an abstract ecosystem composed of a single limiting resource and

  11. Modeling ecological traps for the control of feral pigs.

    PubMed

    Dexter, Nick; McLeod, Steven R

    2015-05-01

    Ecological traps are habitat sinks that are preferred by dispersing animals but have higher mortality or reduced fecundity compared to source habitats. Theory suggests that if mortality rates are sufficiently high, then ecological traps can result in extinction. An ecological trap may be created when pest animals are controlled in one area, but not in another area of equal habitat quality, and when there is density-dependent immigration from the high-density uncontrolled area to the low-density controlled area. We used a logistic population model to explore how varying the proportion of habitat controlled, control mortality rate, and strength of density-dependent immigration for feral pigs could affect the long-term population abundance and time to extinction. Increasing control mortality, the proportion of habitat controlled and the strength of density-dependent immigration decreased abundance both within and outside the area controlled. At higher levels of these parameters, extinction was achieved for feral pigs. We extended the analysis with a more complex stochastic, interactive model of feral pig dynamics in the Australian rangelands to examine how the same variables as the logistic model affected long-term abundance in the controlled and uncontrolled area and time to extinction. Compared to the logistic model of feral pig dynamics, the stochastic interactive model predicted lower abundances and extinction at lower control mortalities and proportions of habitat controlled. To improve the realism of the stochastic interactive model, we substituted fixed mortality rates with a density-dependent control mortality function, empirically derived from helicopter shooting exercises in Australia. Compared to the stochastic interactive model with fixed mortality rates, the model with the density-dependent control mortality function did not predict as substantial decline in abundance in controlled or uncontrolled areas or extinction for any combination of variables. These models demonstrate that pest eradication is theoretically possible without the pest being controlled throughout its range because of density-dependent immigration into the area controlled. The stronger the density-dependent immigration, the better the overall control in controlled and uncontrolled habitat combined. However, the stronger the density-dependent immigration, the poorer the control in the area controlled. For feral pigs, incorporating environmental stochasticity improves the prospects for eradication, but adding a realistic density-dependent control function eliminates these prospects. PMID:26045954

  12. Modeling ecological traps for the control of feral pigs

    PubMed Central

    Dexter, Nick; McLeod, Steven R

    2015-01-01

    Ecological traps are habitat sinks that are preferred by dispersing animals but have higher mortality or reduced fecundity compared to source habitats. Theory suggests that if mortality rates are sufficiently high, then ecological traps can result in extinction. An ecological trap may be created when pest animals are controlled in one area, but not in another area of equal habitat quality, and when there is density-dependent immigration from the high-density uncontrolled area to the low-density controlled area. We used a logistic population model to explore how varying the proportion of habitat controlled, control mortality rate, and strength of density-dependent immigration for feral pigs could affect the long-term population abundance and time to extinction. Increasing control mortality, the proportion of habitat controlled and the strength of density-dependent immigration decreased abundance both within and outside the area controlled. At higher levels of these parameters, extinction was achieved for feral pigs. We extended the analysis with a more complex stochastic, interactive model of feral pig dynamics in the Australian rangelands to examine how the same variables as the logistic model affected long-term abundance in the controlled and uncontrolled area and time to extinction. Compared to the logistic model of feral pig dynamics, the stochastic interactive model predicted lower abundances and extinction at lower control mortalities and proportions of habitat controlled. To improve the realism of the stochastic interactive model, we substituted fixed mortality rates with a density-dependent control mortality function, empirically derived from helicopter shooting exercises in Australia. Compared to the stochastic interactive model with fixed mortality rates, the model with the density-dependent control mortality function did not predict as substantial decline in abundance in controlled or uncontrolled areas or extinction for any combination of variables. These models demonstrate that pest eradication is theoretically possible without the pest being controlled throughout its range because of density-dependent immigration into the area controlled. The stronger the density-dependent immigration, the better the overall control in controlled and uncontrolled habitat combined. However, the stronger the density-dependent immigration, the poorer the control in the area controlled. For feral pigs, incorporating environmental stochasticity improves the prospects for eradication, but adding a realistic density-dependent control function eliminates these prospects. PMID:26045954

  13. Journal of Applied Ecology 2005

    E-print Network

    Fernández-Juricic, Esteban

    Journal of Applied Ecology 2005 42, 943­953 © 2005 British Ecological Society Blackwell Publishing, 621 Charles E. Young Drive South, University of California, Los Angeles, CA 90095­1606, USA.Thesestudiesidentified a number of potential predictive variables. 3. We developed a simulation model that investigates

  14. Homogenization of large-scale movement models in ecology.

    PubMed

    Garlick, Martha J; Powell, James A; Hooten, Mevin B; McFarlane, Leslie R

    2011-09-01

    A difficulty in using diffusion models to predict large scale animal population dispersal is that individuals move differently based on local information (as opposed to gradients) in differing habitat types. This can be accommodated by using ecological diffusion. However, real environments are often spatially complex, limiting application of a direct approach. Homogenization for partial differential equations has long been applied to Fickian diffusion (in which average individual movement is organized along gradients of habitat and population density). We derive a homogenization procedure for ecological diffusion and apply it to a simple model for chronic wasting disease in mule deer. Homogenization allows us to determine the impact of small scale (10-100 m) habitat variability on large scale (10-100 km) movement. The procedure generates asymptotic equations for solutions on the large scale with parameters defined by small-scale variation. The simplicity of this homogenization procedure is striking when compared to the multi-dimensional homogenization procedure for Fickian diffusion,and the method will be equally straightforward for more complex models. PMID:21194012

  15. Application of QUAL2K Model to Assess Ecological Purification Technology for a Polluted River

    PubMed Central

    Zhu, Wenting; Niu, Qian; Zhang, Ruibin; Ye, Rui; Qian, Xin; Qian, Yu

    2015-01-01

    Industrialization and urbanization have caused water pollution and ecosystem degradation, especially in urban canals and rivers in China; accordingly, effective water quality improvement programs are needed. In this study, the Tianlai River in Jiangsu, China was taken as a research site, and a combination of ecological purification technologies consisting of biological rope, phytoremediation, and activated carbon were applied in a laboratory-scale study to examine degradation coefficients under dynamic water conditions. Coefficients were then input into the QUAL2K model to simulate various hypothetical scenarios and determine the minimum density of ecological purification combination and hydraulic retention time (HRT) to meet Grade V or IV of the China standard for surface water. The minimum densities for Grade V and IV were 1.6 times and 2 times the experimental density, while the minimum HRTs for Grade V and IV were 2.4 day and 3 day. The results of this study should provide a practical and efficient design method for ecological purification programs. PMID:25689997

  16. Application of QUAL2K model to assess ecological purification technology for a polluted river.

    PubMed

    Zhu, Wenting; Niu, Qian; Zhang, Ruibin; Ye, Rui; Qian, Xin; Qian, Yu

    2015-02-01

    Industrialization and urbanization have caused water pollution and ecosystem degradation, especially in urban canals and rivers in China; accordingly, effective water quality improvement programs are needed. In this study, the Tianlai River in Jiangsu, China was taken as a research site, and a combination of ecological purification technologies consisting of biological rope, phytoremediation, and activated carbon were applied in a laboratory-scale study to examine degradation coefficients under dynamic water conditions. Coefficients were then input into the QUAL2K model to simulate various hypothetical scenarios and determine the minimum density of ecological purification combination and hydraulic retention time (HRT) to meet Grade V or IV of the China standard for surface water. The minimum densities for Grade V and IV were 1.6 times and 2 times the experimental density, while the minimum HRTs for Grade V and IV were 2.4 day and 3 day. The results of this study should provide a practical and efficient design method for ecological purification programs. PMID:25689997

  17. Creating Simulated Microgravity Patient Models

    NASA Technical Reports Server (NTRS)

    Hurst, Victor; Doerr, Harold K.; Bacal, Kira

    2004-01-01

    The Medical Operational Support Team (MOST) has been tasked by the Space and Life Sciences Directorate (SLSD) at the NASA Johnson Space Center (JSC) to integrate medical simulation into 1) medical training for ground and flight crews and into 2) evaluations of medical procedures and equipment for the International Space Station (ISS). To do this, the MOST requires patient models that represent the physiological changes observed during spaceflight. Despite the presence of physiological data collected during spaceflight, there is no defined set of parameters that illustrate or mimic a 'space normal' patient. Methods: The MOST culled space-relevant medical literature and data from clinical studies performed in microgravity environments. The areas of focus for data collection were in the fields of cardiovascular, respiratory and renal physiology. Results: The MOST developed evidence-based patient models that mimic the physiology believed to be induced by human exposure to a microgravity environment. These models have been integrated into space-relevant scenarios using a human patient simulator and ISS medical resources. Discussion: Despite the lack of a set of physiological parameters representing 'space normal,' the MOST developed space-relevant patient models that mimic microgravity-induced changes in terrestrial physiology. These models are used in clinical scenarios that will medically train flight surgeons, biomedical flight controllers (biomedical engineers; BME) and, eventually, astronaut-crew medical officers (CMO).

  18. Modeling and Simulation: PowerBoosting Productivity with Simulation.

    ERIC Educational Resources Information Center

    Riley, Suzanne

    Minnesota high school students and teachers are learning the technology of simulation and integrating it into business and industrial technology courses. Modeling and simulation is the science of using software to construct a system within an organization and then running simulations of proposed changes to assess results before funds are spent. In…

  19. RIGOROUS MODELING AND SIMULATION OF MECHATRONIC SYSTEMS

    E-print Network

    Taylor, James H.

    RIGOROUS MODELING AND SIMULATION OF MECHATRONIC SYSTEMS James H. Taylor Professor Emeritus, Systems on mechatronic systems. Emphasis is placed on rigorous techniques and selecting the most appropriate method mentioned above for mechatronic systems. Key Words: Mechatronic systems, modeling, simulation, numerical

  20. Simulation modeling with artificial reality technology (SMART): an integration of virtual reality and simulation modeling

    Microsoft Academic Search

    Hank Grant; Chuen-Ki Lai

    1998-01-01

    Simulation Modeling with Artificial Reality Technology (SMART) is a simulation modeling tool that provides a virtual reality interface for building graphical simulation models. The simulation models, comprised of nodes and arcs, are constructed in three dimensions. As the user builds a model, he may immerse himself in it using virtual reality hardware and software tools and take advantage of the

  1. Conservation Models and Ecological Concerns of the Community: A Case-Based Biology Lesson Plan

    NSDL National Science Digital Library

    Fouch, C.

    In this activity, students will design a conservation model that will address the ecological concerns of a community. Students will obtain topographical map of an area and related data; research and analyze appropriate data as to deforestation; survey and select area for removal of trees and landscape according to water flow; and build and produce an ecologically balanced model that will address the concerns of the community. This case will involves the use of botany, environmental science, animal biology, ecology, forestry and mathematics.

  2. Modeling socioeconomic and ecologic aspects of land-use change

    SciTech Connect

    Dale, V.H.; Pedlowski, M.A.; O'Neill, R.V.; Southworth, F.

    1992-01-01

    Land use change is one of the major factors affecting global environmental conditions. Prevalent types of land-use change include replacing forests with agriculture, mines or ranches; forest degradation from collection of firewood; and forest logging. A global effect of wide-scale deforestation is an increase in atmospheric carbon dioxide concentration, which may affect climate. Regional effects include loss of biodiversity and disruption of hydrologic regimes. Local effects include soil erosion, siltation and decreases in soil fertility, loss of extractive reserves, and disruption of indigenous people. Modeling land use change requires combining socioeconomic and ecological factors because socioeconomic forces frequently initiate land-use change and are affected by the subsequent ecological degradation. This paper describes a modeling system that integrates submodels of human colonization and impacts to estimate patterns and rates of deforestation under different immigration and land use scenarios. Immigration which follows road building or paving is a major factor in the rapid deforestation of previously inaccessible areas. Roads facilitate colonization, allow access for large machines, and provide transportation routes for mort of raw materials and produce.

  3. Ecological footprint model using the support vector machine technique.

    PubMed

    Ma, Haibo; Chang, Wenjuan; Cui, Guangbai

    2012-01-01

    The per capita ecological footprint (EF) is one of the most widely recognized measures of environmental sustainability. It aims to quantify the Earth's biological resources required to support human activity. In this paper, we summarize relevant previous literature, and present five factors that influence per capita EF. These factors are: National gross domestic product (GDP), urbanization (independent of economic development), distribution of income (measured by the Gini coefficient), export dependence (measured by the percentage of exports to total GDP), and service intensity (measured by the percentage of service to total GDP). A new ecological footprint model based on a support vector machine (SVM), which is a machine-learning method based on the structural risk minimization principle from statistical learning theory was conducted to calculate the per capita EF of 24 nations using data from 123 nations. The calculation accuracy was measured by average absolute error and average relative error. They were 0.004883 and 0.351078% respectively. Our results demonstrate that the EF model based on SVM has good calculation performance. PMID:22291949

  4. Comparing Aerodynamic Models for Numerical Simulation of

    E-print Network

    Peraire, Jaime

    Comparing Aerodynamic Models for Numerical Simulation of Dynamics and Control of Aircraft and simulation of aircraft, yet other aerodynamics models exist that can provide more accurate results derivatives and other low fidelity models are frequently used in the design and flight simulation of aircraft

  5. Photovoltaic array performance simulation models

    SciTech Connect

    Menicucci, D.F.

    1985-01-01

    The experience of the solar industry confirms that despite recent cost reductions the profitability of photovoltaic (PV) systems is often marginal and the configuration and sizing of a system is a critical problem for the design engineer. Construction and evaluation of experimental systems are expensive and seldom justifiable. A mathematical model or computer simulation program is a desirable alternative, provided reliable results can be obtained. Sandia National Laboratories, Albuquerque (SNLA), has been studying PV system modeling techniques in an effort to develop an effective tool to be used by engineers and architects in the design of cost-effective PV systems. This paper reviews two of the sources of error found in previous PV modeling programs, presents the remedies developed to correct these errors, and describes a new program that incorporates these improvements.

  6. Model Validation with Hybrid Dynamic Simulation

    SciTech Connect

    Huang, Zhenyu; Kosterev, Dmitry; Guttromson, Ross T.; Nguyen, Tony B.

    2006-06-18

    Abstract—Model validation has been one of the central topics in power engineering studies for years. As model validation aims at obtaining reasonable models to represent actual behavior of power system components, it has been essential to validate models against actual measurements or known benchmark behavior. System-wide model simulation results can be compared with actual recordings. However, it is difficult to construct a simulation case for a large power system such as the WECC system and to narrow down to problematic models in a large system. Hybrid dynamic simulation with its capability of injecting external signals into dynamic simulation enables rigorous comparison of measurements and simulation in a small subsystem of interest. This paper presents such a model validation methodology with hybrid dynamic simulation. Two application examples on generator and load model validation are presented to show the validity of this model validation methodology. This methodology is further extended for automatic model validation and dichotomous subsystem model validation.

  7. A model based on Biomimicry to enhance ecologically sustainable design

    Microsoft Academic Search

    Arosha Gamage; Richard Hyde

    2012-01-01

    Sustainable development has become a central part of the agenda in the building design professions; however, in recent years, the concept of ecologically sustainable development has gained ground which aims to balance both economic and environmental facets of sustainability. This has necessitated new approaches to ecological sustainable design that includes ecological facets to design. Such a design approach that draws

  8. Ecological Modelling 170 (2003) 453469 Modeling the brown bear population in Slovenia

    E-print Network

    Dzeroski, Saso

    2003-01-01

    Ecological Modelling 170 (2003) 453­469 Modeling the brown bear population in Slovenia A tool of the core area, and its potential habitat based on natural habitat suitability. Data collected through of the population and maps of its optimal and maximal potential habitat (based on natural suitability). Overall

  9. Simulation, Modelling and Visualisation: Toolkits for Building Simulated Worlds.

    E-print Network

    Hawick, Ken

    Simulation, Modelling and Visualisation: Toolkits for Building Simulated Worlds. D. P. Playne, A. P and particle models to support research with Cahn- Hillard Cook [2] and Ginzburg-Landau equations, artificial and in three dimensions the cells are arranged as a cube. Figure 1: 3D Field Equation Visualisation. Figure 1

  10. Environmental ecological modeling of human blood lead levels in East Asia.

    PubMed

    Niisoe, Tamon; Harada, Kouji H; Hitomi, Toshiaki; Watanabe, Takao; Hung, Nguyen Ngoc; Ishikawa, Hirohiko; Wang, Zifa; Koizumi, Akio

    2011-04-01

    Environmental ecological modeling (EEM), which unifies models simulating transport of chemicals and exposure of humans to chemicals, was used to simulate long-term trends of female adult human blood lead levels (BLLs) and historical exposure to the atmospheric lead in four East Asian countries: Japan, Korea, China, and Vietnam. Anthropogenic lead emissions to the atmosphere in Vietnam were estimated from energy statistics to be 1931 t yr(-1). Calculated BLLs generally agreed with those observed in samples collected in these countries as the error factors were less than 2. The model results revealed that BLLs decreased significantly in Tokyo (by 58%) and Seoul (by 45%) in recent decades and confirmed the effects of efforts to reduce environmental lead in Japan and Korea. The model results also revealed that BLLs in Beijing did not decrease in this decade as much as in Tokyo and Seoul, despite the phasing out of leaded gasoline, and that the contribution from the atmospheric component was increasing (43% in 2009). Finally, we applied EEM to simulate BLLs of children in Hanoi. The probability of children having BLLs greater than 50 ?g L(-1) was 7.5%, which was greater than those observed in developed countries. PMID:21355531

  11. Incorporating Boosted Regression Trees into Ecological Latent Variable Models Rebecca A. Hutchinson and Li-Ping Liu and Thomas G. Dietterich

    E-print Network

    Incorporating Boosted Regression Trees into Ecological Latent Variable Models Rebecca A. Hutchinson ecological phenomena are often observed indirectly. Consequently, probabilistic latent variable models provide an important tool, because they can in- clude explicit models of the ecological phenomenon

  12. Georeferenced model simulations efficiently support targeted monitoring

    NASA Astrophysics Data System (ADS)

    Berlekamp, Jürgen; Klasmeier, Jörg

    2010-05-01

    The European Water Framework Directive (WFD) demands the good ecological and chemical status of surface waters. To meet the definition of good chemical status of the WFD surface water concentrations of priority pollutants must not exceed established environmental quality standards (EQS). Surveillance of the concentrations of numerous chemical pollutants in whole river basins by monitoring is laborious and time-consuming. Moreover, measured data do often not allow for immediate source apportionment which is a prerequisite for defining promising reduction strategies to be implemented within the programme of measures. In this context, spatially explicit model approaches are highly advantageous because they provide a direct link between local point emissions (e.g. treated wastewater) or diffuse non-point emissions (e.g. agricultural runoff) and resulting surface water concentrations. Scenario analyses with such models allow for a priori investigation of potential positive effects of reduction measures such as optimization of wastewater treatment. The geo-referenced model GREAT-ER (Geography-referenced Regional Exposure Assessment Tool for European Rivers) has been designed to calculate spatially resolved averaged concentrations for different flow conditions (e.g. mean or low flow) based on emission estimations for local point source emissions such as treated effluents from wastewater treatment plants. The methodology was applied to selected pharmaceuticals (diclofenac, sotalol, metoprolol, carbamazepin) in the Main river basin in Germany (approx. 27,290 km²). Average concentrations of the compounds were calculated for each river reach in the whole catchment. Simulation results were evaluated by comparison with available data from orienting monitoring and used to develop an optimal monitoring strategy for the assessment of water quality regarding micropollutants at the catchment scale.

  13. Predicting the distribution of Sasquatch in western North America: anything goes with ecological niche modelling

    Microsoft Academic Search

    J. D. Lozier; P. Aniello; M. J. Hickerson

    2009-01-01

    The availability of user-friendly software and publicly available biodiversity databases has led to a rapid increase in the use of ecological niche modelling to predict species distributions. A potential source of error in publicly available data that may affect the accuracy of ecological niche models (ENMs), and one that is difficult to correct for, is incorrect (or incomplete) taxonomy. Here

  14. Ecological Modelling 176 (2004) 6574 Wada basins and qualitative unpredictability in

    E-print Network

    2004-01-01

    Ecological Modelling 176 (2004) 65­74 Wada basins and qualitative unpredictability in ecological of unpredictability is associated with some nonlinear models. The notion of a Wada basin, in which three or more Wada basin boundaries become large, a small amount of stochastic forcing may create chaos-like behavior

  15. MODELING AND SIMULATING HUMAN TEAMWORK BEHAVIORS 1 Modeling and Simulating Human Teamwork

    E-print Network

    MODELING AND SIMULATING HUMAN TEAMWORK BEHAVIORS 1 Modeling and Simulating Human Teamwork Behaviors #12;MODELING AND SIMULATING HUMAN TEAMWORK BEHAVIORS 2 Abstract Among researchers in multi-agent systems there has been growing interest in using intelligent agents to model and simulate human teamwork

  16. Plasma disruption modeling and simulation

    SciTech Connect

    Hassanein, A.

    1994-07-01

    Disruptions in tokamak reactors are considered a limiting factor to successful operation and a reliable design. The behavior of plasma-facing components during a disruption is critical to the overall integrity of the reactor. Erosion of plasma facing-material (PFM) surfaces due to thermal energy dump during the disruption can severely limit the lifetime of these components and thus diminish the economic feasibility of the reactor.Initially, the incident plasma particles will deposit their energy directly on the PFM surface, heating it to a very high temperature where ablation occurs. Models for plasma-material interactions have been developed and used to predict material thermal evolution during the disruption. Within a few microseconds after the start of the disruption, enough material is vaporized to intercept most of the incoming plasma particles. Models for plasma-vapor interactions are necessary to predict vapor cloud expansion and hydrodynamics. Continuous heating of the vapor cloud above the material surface by the incident plasma particles will excite, ionize, and cause vapor atoms to emit thermal radiation. Accurate models for radiation transport in the vapor are essential for calculating the net radiated flux to the material surface which determines the final erosion thickness and consequently component lifetime. A comprehensive model that takes into account various stages of plasma-material interaction has been developed and used to predict erosion rates during reactor disruption, as well during induced disruption in laboratory experiments. Differences between various simulation experiments and reactor conditions are discussed. A two-dimensional radiation transport model has been developed to particularly simulate the effect of small test samples used in laboratory disruption experiments.

  17. Modeling of Army Research Laboratory EMP simulators

    SciTech Connect

    Miletta, J.R.; Chase, R.J.; Luu, B.B. (Army Research Lab., Adelphi, MD (United States)); Williams, J.W.; Viverito, V.J. (Science Applications International Corp., Germantown, MD (United States))

    1993-12-01

    Models are required that permit the estimation of emitted field signatures from EMP simulators to design the simulator antenna structure, to establish the usable test volumes, and to estimate human exposure risk. This paper presents the capabilities and limitations of a variety of EMP simulator models useful to the Army's EMP survivability programs. Comparisons among frequency and time-domain models are provided for two powerful US Army Research Laboratory EMP simulators: AESOP (Army EMP Simulator Operations) and VEMPS II (Vertical EMP Simulator II).

  18. Is it relevant to explicitly parameterize chlorophyll synthesis in marine ecological models?

    NASA Astrophysics Data System (ADS)

    Mateus, M.; Leitão, P. C.; de Pablo, H.; Neves, R.

    2012-06-01

    Oceanographers and modelers often relate chlorophyll concentrations with phytoplankton carbon invoking a suitable C:Chla ratio. However C:Chl ratios are not constant in natural systems, thus making chlorophyll a deceptive measure of true biomass. In this paper we report on the adaptation of an algorithm for chlorophyll synthesis to a complex ecological model for the marine environment. Based on this model we have developed several simulation experiments to assess the performance of the chlorophyll synthesis and the phytoplankton photoadaptation strategy. The model was applied to three distinct settings, comprising distinctive model geometries and ambient conditions: a schematic setting corresponding to a virtual mesocosm without any transport scheme (0D), a 1D vertical open-ocean application to a 150 m deep water-column, and an application to an estuary using a 2D configuration. Conditions vary from spatially stable in the first case to a strong spatial and temporal heterogeneity in the case of the estuary. Our results fall within the range and reproduce some of the trends found in published data, supporting the idea that when conditions have strong changes of nutrient availability and light conditions, a photoacclimation mechanism becomes an essential requirement for reliable chlorophyll biomass estimates. This is particularly relevant if model simulations are to be used to study natural systems complemented by data retrieved from direct measurements.

  19. A modular BLSS simulation model

    NASA Technical Reports Server (NTRS)

    Rummel, John D.; Volk, Tyler

    1987-01-01

    A bioregenerative life support system (BLSS) for extraterrestrial use will be faced with coordination problems more acute than those in any ecosystem found on Earth. A related problem in BLSS design is providing an interface between the various life support processors, one that will allow for their coordination while still allowing for system expansion. A modular model is presented of a BLSS that interfaces system processors only with the material storage reservoirs, allowing those reservoirs to act as the principal buffers in the system and thus minimizing difficulties with processor coordination. The modular nature of the model allows independent development of the detailed submodels that exist within the model framework. Using this model, BLSS dynamics were investigated under normal conditions and under various failure modes. Partial and complete failures of various components, such as the waste processors or the plants themselves, drive transient responses in the model system, allowing the examination of the effectiveness of the system reservoirs as buffers. The results from simulations help to determine control strategies and BLSS design requirements. An evolved version could be used as an interactive control aid in a future BLSS.

  20. Theoretically exploring direct and indirect chemical effects across ecological and exposure scenarios using mechanistic fate and effects modelling.

    PubMed

    De Laender, F; Morselli, M; Baveco, H; Van den Brink, P J; Di Guardo, A

    2015-01-01

    Predicting ecosystem response to chemicals is a complex problem in ecotoxicology and a challenge for risk assessors. The variables potentially influencing chemical fate and exposure define the exposure scenario while the variables determining effects at the ecosystem level define the ecological scenario. In absence of any empirical data, the objective of this paper is to present simulations by a fugacity-based fate model and a differential equation-based ecosystem model to theoretically explore how direct and indirect effects on invertebrate shallow pond communities vary with changing ecological and exposure scenarios. These simulations suggest that direct and indirect effects are larger in mesotrophic systems than in oligotrophic systems. In both trophic states, interaction strength (quantified using grazing rates) was suggested a more important driver for the size and recovery from direct and indirect effects than immigration rate. In general, weak interactions led to smaller direct and indirect effects. For chemicals targeting mesozooplankton only, indirect effects were common in (simple) food-chains but rare in (complex) food-webs. For chemicals directly affecting microzooplankton, the dominant zooplankton group in the modelled community, indirect effects occurred both in food-chains and food-webs. We conclude that the choice of the ecological and exposure scenarios in ecotoxicological modelling efforts needs to be justified because of its influence on the prevalence and magnitude of the predicted effects. Overall, more work needs to be done to empirically test the theoretical expectations formulated here. PMID:25454235

  1. Hierarchical modeling and inference in ecology: The analysis of data from populations, metapopulations and communities

    USGS Publications Warehouse

    Royle, J.A.; Dorazio, R.M.

    2008-01-01

    A guide to data collection, modeling and inference strategies for biological survey data using Bayesian and classical statistical methods. This book describes a general and flexible framework for modeling and inference in ecological systems based on hierarchical models, with a strict focus on the use of probability models and parametric inference. Hierarchical models represent a paradigm shift in the application of statistics to ecological inference problems because they combine explicit models of ecological system structure or dynamics with models of how ecological systems are observed. The principles of hierarchical modeling are developed and applied to problems in population, metapopulation, community, and metacommunity systems. The book provides the first synthetic treatment of many recent methodological advances in ecological modeling and unifies disparate methods and procedures. The authors apply principles of hierarchical modeling to ecological problems, including * occurrence or occupancy models for estimating species distribution * abundance models based on many sampling protocols, including distance sampling * capture-recapture models with individual effects * spatial capture-recapture models based on camera trapping and related methods * population and metapopulation dynamic models * models of biodiversity, community structure and dynamics.

  2. Simulation model development in information security education

    Microsoft Academic Search

    Jose M. Garrido; Tridib Bandyopadhyay

    2009-01-01

    The value of modeling and simulation for education, training, and testing in information security has been documented in several studies. In this paper, we suggest that it is important not only to include the general use of simulation in various courses of the security curriculum, but also to include the theory and development of simulation models. We describe briefly the

  3. Verification and validation of simulation models

    Microsoft Academic Search

    Jack P. C. Kleijnen

    1995-01-01

    This paper surveys verification and validation of models, especially simulation models in operations research. For verification it discusses 1) general good programming practice (such as modular programming), 2) checking intermediate simulation outputs through tracing and statistical testing per module, 3) statistical testing of final simulation outputs against analytical results, and 4) animation. For validation it discusses 1) obtaining real-worl data,

  4. Dynamic fabric modelling and simulation using deformable models

    Microsoft Academic Search

    Hassen Hedfi; Adel Ghith; Hédi BelHadjSalah

    2011-01-01

    This paper proposes a modelling of the dynamic behaviour of textile fabrics based on a new formulation of deformable models. Deformable models such as those that were introduced by Terzopoulos in 1987 for modelling and simulation of deformable objects in computer graphics are reformulated to simulate textile woven fabrics. This investigation tends to produce simulations of textile fabrics showing the

  5. Multiple model simulation: modelling cell division and differentiation in the

    E-print Network

    Stepney, Susan

    behaviours are simulated in the modified-prostate simulation; (c) to experiment with the vari- ous formsMultiple model simulation: modelling cell division and differentiation in the prostate Alastair this approach to building a model of prostate cell division and differentiation, with each model layer

  6. Understanding Climate Change through Modelling and Simulation: A Case for Verification, Validation and Accreditation

    Microsoft Academic Search

    A. J. Masys

    2006-01-01

    The challenges associated with understanding Climate Change (CC) and subsequent socio-technical solutions stem from the complexity and uncertainties inherent within the mechanisms, magnitudes and temporal nature of the environment. Modelling & Simulation (M&S) has flourished as an enabling technology providing insight into the intricacies of Climate Change as well as facilitating understanding regarding the social and ecological implications of these

  7. Integrated Bayesian network framework for modeling complex ecological issues.

    PubMed

    Johnson, Sandra; Mengersen, Kerrie

    2012-07-01

    The management of environmental problems is multifaceted, requiring varied and sometimes conflicting objectives and perspectives to be considered. Bayesian network (BN) modeling facilitates the integration of information from diverse sources and is well suited to tackling the management challenges of complex environmental problems. However, combining several perspectives in one model can lead to large, unwieldy BNs that are difficult to maintain and understand. Conversely, an oversimplified model may lead to an unrealistic representation of the environmental problem. Environmental managers require the current research and available knowledge about an environmental problem of interest to be consolidated in a meaningful way, thereby enabling the assessment of potential impacts and different courses of action. Previous investigations of the environmental problem of interest may have already resulted in the construction of several disparate ecological models. On the other hand, the opportunity may exist to initiate this modeling. In the first instance, the challenge is to integrate existing models and to merge the information and perspectives from these models. In the second instance, the challenge is to include different aspects of the environmental problem incorporating both the scientific and management requirements. Although the paths leading to the combined model may differ for these 2 situations, the common objective is to design an integrated model that captures the available information and research, yet is simple to maintain, expand, and refine. BN modeling is typically an iterative process, and we describe a heuristic method, the iterative Bayesian network development cycle (IBNDC), for the development of integrated BN models that are suitable for both situations outlined above. The IBNDC approach facilitates object-oriented BN (OOBN) modeling, arguably viewed as the next logical step in adaptive management modeling, and that embraces iterative development. The benefits of OOBN modeling in the environmental community have not yet been fully realized in environmental management research. The IBNDC approach to BN modeling is described in the context of 2 case studies. The first is the initiation of blooms of Lyngbya majuscula, a blue-green algae, in Deception Bay, Australia where 3 existing models are being integrated, and the second case study is the viability of the free-ranging cheetah (Acinonyx jubatus) population in Namibia where an integrated OOBN model is created consisting of 3 independent subnetworks, each describing a particular aspect of free-ranging cheetah population conservation. PMID:21853523

  8. Monte Carlo simulation of ice models

    SciTech Connect

    Barkema, G.T. [HLRZ, Forschungszentrum Juelich, 52425 Juelich (Germany)] [HLRZ, Forschungszentrum Juelich, 52425 Juelich (Germany); Newman, M.E. [Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, New Mexico 87501 (United States)] [Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, New Mexico 87501 (United States)

    1998-01-01

    We study a number of Monte Carlo algorithms for the simulation of ice models, and compare their efficiency. One of them, a cluster algorithm for the equivalent three-color model, appears to have a dynamic exponent close to zero, making it particularly useful for simulations of critical ice models. We have performed extensive simulations using our algorithms to determine a number of critical exponents for the square ice and F models. {copyright} {ital 1998} {ital The American Physical Society}

  9. A National Disturbance Modeling System to Support Ecological Carbon Sequestration Assessments

    NASA Astrophysics Data System (ADS)

    Hawbaker, T. J.; Rollins, M. G.; Volegmann, J. E.; Shi, H.; Sohl, T. L.

    2009-12-01

    The U.S. Geological Survey (USGS) is prototyping a methodology to fulfill requirements of Section 712 of the Energy Independence and Security Act (EISA) of 2007. At the core of the EISA requirements is the development of a methodology to complete a two-year assessment of current carbon stocks and other greenhouse gas (GHG) fluxes, and potential increases for ecological carbon sequestration under a range of future climate changes, land-use / land-cover configurations, and policy, economic and management scenarios. Disturbances, especially fire, affect vegetation dynamics and ecosystem processes, and can also introduce substantial uncertainty and risk to the efficacy of long-term carbon sequestration strategies. Thus, the potential impacts of disturbances need to be considered under different scenarios. As part of USGS efforts to meet EISA requirements, we developed the National Disturbance Modeling System (NDMS) using a series of statistical and process-based simulation models. NDMS produces spatially-explicit forecasts of future disturbance locations and severity, and the resulting effects on vegetation dynamics. NDMS is embedded within the Forecasting Scenarios of Future Land Cover (FORE-SCE) model and informs the General Ensemble Biogeochemical Modeling System (GEMS) for quantifying carbon stocks and GHG fluxes. For fires, NDMS relies on existing disturbance histories, such as the Landsat derived Monitoring Trends in Burn Severity (MTBS) and Vegetation Change Tracker (VCT) data being used to update LANDFIRE fuels data. The MTBS and VCT data are used to parameterize models predicting the number and size of fires in relation to climate, land-use/land-cover change, and socioeconomic variables. The locations of individual fire ignitions are determined by an ignition probability surface and then FARSITE is used to simulate fire spread in response to weather, fuels, and topography. Following the fire spread simulations, a burn severity model is used to determine annual changes in biomass pools. Vegetation succession among LANDFIRE vegetation types is initiated using burn perimeter and severity data at the end of each annual simulation. Results from NDMS are used to update land-use/land-cover layers used by FORE-SCE and also transferred to GEMS for quantifying and updating carbon stocks and greenhouse gas fluxes. In this presentation, we present: 1) an overview of NDMS and its role in USGS's national ecological carbon sequestration assessment; 2) validation of NDMS using historic data; and 3) initial forecasts of disturbances for the southeastern United States and their impacts on greenhouse gas emissions, and post-fire carbon stocks and fluxes.

  10. Social network models predict movement and connectivity in ecological landscapes

    USGS Publications Warehouse

    Fletcher, Robert J., Jr.; Acevedo, M.A.; Reichert, B.E.; Pias, K.E.; Kitchens, Wiley M.

    2011-01-01

    Network analysis is on the rise across scientific disciplines because of its ability to reveal complex, and often emergent, patterns and dynamics. Nonetheless, a growing concern in network analysis is the use of limited data for constructing networks. This concern is strikingly relevant to ecology and conservation biology, where network analysis is used to infer connectivity across landscapes. In this context, movement among patches is the crucial parameter for interpreting connectivity but because of the difficulty of collecting reliable movement data, most network analysis proceeds with only indirect information on movement across landscapes rather than using observed movement to construct networks. Statistical models developed for social networks provide promising alternatives for landscape network construction because they can leverage limited movement information to predict linkages. Using two mark-recapture datasets on individual movement and connectivity across landscapes, we test whether commonly used network constructions for interpreting connectivity can predict actual linkages and network structure, and we contrast these approaches to social network models. We find that currently applied network constructions for assessing connectivity consistently, and substantially, overpredict actual connectivity, resulting in considerable overestimation of metapopulation lifetime. Furthermore, social network models provide accurate predictions of network structure, and can do so with remarkably limited data on movement. Social network models offer a flexible and powerful way for not only understanding the factors influencing connectivity but also for providing more reliable estimates of connectivity and metapopulation persistence in the face of limited data.

  11. Propulsion System Modeling and Simulation

    NASA Technical Reports Server (NTRS)

    Tai, Jimmy C. M.; McClure, Erin K.; Mavris, Dimitri N.; Burg, Cecile

    2002-01-01

    The Aerospace Systems Design Laboratory at the School of Aerospace Engineering in Georgia Institute of Technology has developed a core competency that enables propulsion technology managers to make technology investment decisions substantiated by propulsion and airframe technology system studies. This method assists the designer/manager in selecting appropriate technology concepts while accounting for the presence of risk and uncertainty as well as interactions between disciplines. This capability is incorporated into a single design simulation system that is described in this paper. This propulsion system design environment is created with a commercially available software called iSIGHT, which is a generic computational framework, and with analysis programs for engine cycle, engine flowpath, mission, and economic analyses. iSIGHT is used to integrate these analysis tools within a single computer platform and facilitate information transfer amongst the various codes. The resulting modeling and simulation (M&S) environment in conjunction with the response surface method provides the designer/decision-maker an analytical means to examine the entire design space from either a subsystem and/or system perspective. The results of this paper will enable managers to analytically play what-if games to gain insight in to the benefits (and/or degradation) of changing engine cycle design parameters. Furthermore, the propulsion design space will be explored probabilistically to show the feasibility and viability of the propulsion system integrated with a vehicle.

  12. Modeling and simulation: tools for metabolic engineering

    Microsoft Academic Search

    Wolfgang Wiechert

    2002-01-01

    Mathematical modeling is one of the key methodologies of metabolic engineering. Based on a given metabolic model different computational tools for the simulation, data evaluation, systems analysis, prediction, design and optimization of metabolic systems have been developed. The currently used metabolic modeling approaches can be subdivided into structural models, stoichiometric models, carbon flux models, stationary and nonstationary mechanistic models and

  13. Implementation and Performance of Parallel Ecological Simulations \\Lambda William Maniatty, Boleslaw Szymanski a and Tom Caraco b

    E-print Network

    Maniatty, William A.

    Implementation and Performance of Parallel Ecological Simulations \\Lambda William Maniatty of the automaton are discrete sites into which the habitat is partitioned. Probabilistic local state transitions of the habitat that are challenging to implement efficiently on SIMD machines. For exam­ ple, pattern detection

  14. An introduction to enterprise modeling and simulation

    SciTech Connect

    Ostic, J.K.; Cannon, C.E. [Los Alamos National Lab., NM (United States). Technology Modeling and Analysis Group

    1996-09-01

    As part of an ongoing effort to continuously improve productivity, quality, and efficiency of both industry and Department of Energy enterprises, Los Alamos National Laboratory is investigating various manufacturing and business enterprise simulation methods. A number of enterprise simulation software models are being developed to enable engineering analysis of enterprise activities. In this document the authors define the scope of enterprise modeling and simulation efforts, and review recent work in enterprise simulation at Los Alamos National Laboratory as well as at other industrial, academic, and research institutions. References of enterprise modeling and simulation methods and a glossary of enterprise-related terms are provided.

  15. Individuals and their ecologies: analysing the geography of chronic illness within a multilevel modelling framework

    Microsoft Academic Search

    Kelvyn Jones; Craig Duncan

    1995-01-01

    This paper argues for the importance of place differences in understanding chronic illness. A conceptual distinction is drawn between individual and ecological effects and it is argued that aggregate analysis provides an inappropriate methodology for studying place differences. Multilevel modelling, in contrast, allows for the simultaneous analysis of individuals and their ecologies. This approach is applied to data derived from

  16. A conceptual modeling of ecological greywater recycling system in Kuching city, Sarawak, Malaysia

    Microsoft Academic Search

    Darrien Yau Seng Mah; Charles Hin Joo Bong; Frederik Josep Putuhena; Salim Said

    2009-01-01

    A pilot project of greywater ecological treatment is established in Kuching city since 2003. Such treatment facility opens up an opportunity of wastewater reclamation for reuse as secondary sources of water for non-consumptive purposes. This paper aims in exploring the potential of the intended purposes in the newly developed ecological treatment project. The modeling process of using a mathematical representation

  17. Ecological Modelling 170 (2003) 219226 Using regression trees to identify the habitat preference of the sea

    E-print Network

    Dzeroski, Saso

    2003-01-01

    Ecological Modelling 170 (2003) 219­226 Using regression trees to identify the habitat preference rights reserved. Keywords: Machine learning; Tropical marine ecology; Habitat preference; Sea cucumber 1 and habitat requirements of a species can significantly enhance conservation efforts. The sea cucumber

  18. Regional Ecological Risk Assessment for Australia's Tropical Rivers: Application of the Relative Risk Model

    Microsoft Academic Search

    R. E. Bartolo; R. A. van Dam; P. Bayliss

    2012-01-01

    The Relative Risk Model (RRM) was used to undertake a spatially explicit regional ecological risk assessment at a continental scale for the 1.1 million km Northern Tropical Rivers (NTR) region of Australia, and at a catchment scale for the Daly River, Northern Territory. The NTR RRM assessed risks of 18 threats to three aquatic habitats and four ecological assessment endpoints

  19. The Efficacy of Ecological Macro-Models in Preservice Teacher Education: Transforming States of Mind

    ERIC Educational Resources Information Center

    Stibbards, Adam; Puk, Tom

    2011-01-01

    The present study aimed to describe and evaluate a transformative, embodied, emergent learning approach to acquiring ecological literacy through higher education. A class of teacher candidates in a bachelor of education program filled out a survey, which had them rate their level of agreement with 15 items related to ecological macro-models.…

  20. Violent Victimization and Perpetration during Adolescence: Developmental Stage Dependent Ecological Models

    ERIC Educational Resources Information Center

    Matjasko, Jennifer L.; Needham, Belinda L.; Grunden, Leslie N.; Farb, Amy Feldman

    2010-01-01

    Using a variant of the ecological-transactional model and developmental theories of delinquency on a nationally representative sample of adolescents, the current study explored the ecological predictors of violent victimization, perpetration, and both for three different developmental stages during adolescence. We examined the relative influence…

  1. Credibility Evaluation of Missile Flight Simulation Model

    Microsoft Academic Search

    Yanyan Zhou; Dongyang Zhang; Baoxiang Ren

    2010-01-01

    In this paper, credibility evaluation issue of missile flight simulation model is studying by applying neural network technique. Aiming at the subsistent insufficiency of model validation method in application, we present a credibility evaluation method based on neural network. Which uses the powerful ability of nonlinearity mapping of neural network by utilizing missile flight state data of simulation model as

  2. Assimilating LANDSAT data in an ecosystem model for multi-year simulation of grassland carbon, water and energy budget

    Microsoft Academic Search

    Y. Nouvellon; M. S. Moran; A. Chehbouniz; D. Lo Seen; R. Bryant; M. Nichols; L. Prevot; S. Rambal; W. Ni; A. Begue; P. Heilman; T. O. Keefer

    2000-01-01

    In this study, a spatially explicit hydro-ecological model (SEHEM) has been developed and validated over a semi-arid grassland sub-watershed in Arizona. The model combines a plant growth sub-model to simulate the seasonal dynamics of root and aboveground biomass, and a hydrological sub-model to simulate soil moisture and temperature dynamics, energy and water budgets for the soil and the vegetation. In

  3. Aeroacoustic simulation for phonation modeling

    NASA Astrophysics Data System (ADS)

    Irwin, Jeffrey; Hanford, Amanda; Craven, Brent; Krane, Michael

    2011-11-01

    The phonation process occurs as air expelled from the lungs creates a pressure drop and a subsequent air flow across the larynx. The fluid-structure interaction between the turbulent air flow and oscillating vocal folds, combined with additional resonance in the oral and nasal cavities, creates much of what we hear in the human voice. As many voice-related disorders can be traced to irregular vocal tract shape or motion, it is important to understand in detail the physics involved in the phonation process. To numerically compute the physics of phonation, a solver must be able to accurately model acoustic airflow through a moving domain. The open-source CFD package OpenFOAM is currently being used to evaluate existing solvers against simple acoustic test cases, including an open-ended resonator and an expansion chamber, both of which utilize boundary conditions simulating acoustic sources as well as anechoic termination. Results of these test cases will be presented and compared with theory, and the future development of a three-dimensional vocal tract model and custom-mode acoustic solver will be discussed. Acknowledge support of NIH grant 5R01DC005642 and ARL E&F program.

  4. Testing Natureserve's ecological integrity assessment model in Michigan and Indiana

    EPA Science Inventory

    NatureServe, in partnership with member programs from the Natural Heritage Network and federal agencies, has developed an assessment of ecosystems condition, structured around the concept of ecological integrity. Our multi-metric approach for our Ecological Integrity Assessment m...

  5. Theory, Modeling, and Simulation of Semiconductor Lasers

    NASA Technical Reports Server (NTRS)

    Ning, Cun-Zheng; Saini, Subbash (Technical Monitor)

    1998-01-01

    Semiconductor lasers play very important roles in many areas of information technology. In this talk, I will first give an overview of semiconductor laser theory. This will be followed by a description of different models and their shortcomings in modeling and simulation. Our recent efforts in constructing a fully space and time resolved simulation model will then be described. Simulation results based on our model will be presented. Finally the effort towards a self-consistent and comprehensive simulation capability for the opto-electronics integrated circuits (OEICs) will be briefly reviewed.

  6. Verification, validation and accreditation of simulation models

    Microsoft Academic Search

    Robert G. Sargent

    2000-01-01

    The paper discusses verification, validation, and accreditation of simulation models. The different approaches to deciding model validity are presented; how model verification and validation relate to the model development process are discussed; various validation techniques are defined; conceptual model validity, model verification, operational validity, and data validity are described; ways to document results are given; a recommended procedure is presented;

  7. Framework for analyzing ecological trait-based models in multidimensional niche spaces

    NASA Astrophysics Data System (ADS)

    Biancalani, Tommaso; DeVille, Lee; Goldenfeld, Nigel

    2015-05-01

    We develop a theoretical framework for analyzing ecological models with a multidimensional niche space. Our approach relies on the fact that ecological niches are described by sequences of symbols, which allows us to include multiple phenotypic traits. Ecological drivers, such as competitive exclusion, are modeled by introducing the Hamming distance between two sequences. We show that a suitable transform diagonalizes the community interaction matrix of these models, making it possible to predict the conditions for niche differentiation and, close to the instability onset, the asymptotically long time population distributions of niches. We exemplify our method using the Lotka-Volterra equations with an exponential competition kernel.

  8. Modelling and simulation of a heat exchanger

    NASA Technical Reports Server (NTRS)

    Xia, Lei; Deabreu-Garcia, J. Alex; Hartley, Tom T.

    1991-01-01

    Two models for two different control systems are developed for a parallel heat exchanger. First by spatially lumping a heat exchanger model, a good approximate model which has a high system order is produced. Model reduction techniques are applied to these to obtain low order models that are suitable for dynamic analysis and control design. The simulation method is discussed to ensure a valid simulation result.

  9. A simulation oriented animation description model

    Microsoft Academic Search

    Huadoug Ma; Shenquan Liu

    1994-01-01

    Introduces a simulation-oriented animation description model-the temporal logic-based animation description (TLAD) model-and an animation description language based on this model. This model has a powerful description ability, is easy to implement and convenient to use. The model can be used to describe complex animation simulations such as concurrency and path planning. Finally, we describe how to implement an animation system

  10. Modeling supersclar processors via statisical simulation

    Microsoft Academic Search

    Richard Carl; J. E. Smith

    1998-01-01

    Statistical simulation is a technique for fast per-formance evaluation of superscalar processors. First, intrinsic statistical information is collected from a single detailed simulation of a program. This information is then used to generate a synthetic instruction trace that is fed to a simple processor model, along with cache and branch prediction statistics. Because of the probabilistic nature of the simulation,

  11. The Role of Aircraft Noise Simulation Models

    Microsoft Academic Search

    Kenneth J. Plotkin

    Noise simulation models, which compute detailed time histories of noise at a given point, have usually been considered to be specialized research tools. There are, however, situations where the detail provided by simulation can be important, and advances in computing power have made simulation practical for a wider range of problems than in the past. This paper describes the structure

  12. Modeling and simulation of WSN routing protocols

    Microsoft Academic Search

    Xiaoyu Song

    2011-01-01

    In this paper, the simulation and analysis are given to the network simulation tool OPNET network model of the LEACH protocol. The simulation results show that the improved routing algorithm I-LEACH (Improved-LEACH) is better than the original LEACH algorithm that extends the network life cycle, reducing the overall system energy consumption and enhancing the network scalability.

  13. Monte Carlo Simulations of Model Nonionic Surfactants

    E-print Network

    Monte Carlo Simulations of Model Nonionic Surfactants A.P. Chatterjee and A.Z. Panagiotopoulos was studied by histogram reweight- ing grand canonical Monte Carlo simulations. Two di erent sets of site volume fractions using lattice Monte Carlo simulations performed in the canonical constant NV T ensemble

  14. Multi-Model Investigation of Ecological Response to Extreme Events

    NASA Astrophysics Data System (ADS)

    Xu, L.; Kicklighter, D. W.; Felzer, B. S.; Schlosser, C. A.; Chang, K.; Paw U, K.

    2013-12-01

    Extreme events such as droughts and heat waves have serious and damaging impacts on terrestrial processes. Under climate change, these extreme weather events are likely to shift in both magnitude and frequency at regional and local scales. The resulting interactions and feedbacks between the terrestrial and atmosphere systems could lead to non-linear and/or threshold responses in the eco-climate system, and raise a concern as to the resiliency of natural as well as managed ecosystems under extreme changes. This study investigates the response of ecosystem to droughts at different time scales and magnitudes. Four land surface models with different bio-geophysical parameterizations and representations are used to simulate soil-canopy processes, such as evapotranspiration, during these extreme events. The Terrestrial Ecosystem Model (TEM) is a process-based ecosystem model that uses spatially referenced information on climate, elevation, soils, vegetation and water availability to make monthly estimates of vegetation and soil carbon and nitrogen fluxes and pool sizes. There are two versions of TEM model, the TEM-Hydro daily model and the TEM monthly model. The Advanced Canopy-Atmosphere-Soil Algorithm (ACASA) is a multi-layered land surface model based on eddy-covariance theory to calculate the biosphere-atmosphere exchanges of carbon dioxide, water, and momentums. The Community Land Model (CLM) is a community-based model consists of biogeophysics, hydrological cycle, biogeochemistry and dynamic vegetation. Model simulations are evaluated using the biogeophysical and micrometeorological field observations from the AmeriFlux sites across the US. Preliminary results indicate that during a severe drought the link between evapotranspiration and Net Ecosystem Productivity (NEP) in the models is weaker than what observations indicate. This and other interpretations are presented and discussed.

  15. Automated experimentation in ecological networks

    PubMed Central

    2011-01-01

    Background In ecological networks, natural communities are studied from a complex systems perspective by representing interactions among species within them in the form of a graph, which is in turn analysed using mathematical tools. Topological features encountered in complex networks have been proved to provide the systems they represent with interesting attributes such as robustness and stability, which in ecological systems translates into the ability of communities to resist perturbations of different kinds. A focus of research in community ecology is on understanding the mechanisms by which these complex networks of interactions among species in a community arise. We employ an agent-based approach to model ecological processes operating at the species' interaction level for the study of the emergence of organisation in ecological networks. Results We have designed protocols of interaction among agents in a multi-agent system based on ecological processes occurring at the interaction level between species in plant-animal mutualistic communities. Interaction models for agents coordination thus engineered facilitate the emergence of network features such as those found in ecological networks of interacting species, in our artificial societies of agents. Conclusions Agent based models developed in this way facilitate the automation of the design an execution of simulation experiments that allow for the exploration of diverse behavioural mechanisms believed to be responsible for community organisation in ecological communities. This automated way of conducting experiments empowers the study of ecological networks by exploiting the expressive power of interaction models specification in agent systems. PMID:21554669

  16. Public sector administration of ecological economics systems using mediated modeling.

    PubMed

    van den Belt, Marjan; Kenyan, Jennifer R; Krueger, Elizabeth; Maynard, Alison; Roy, Matthew Galen; Raphael, Ian

    2010-01-01

    In today's climate of government outsourcing and multiple stakeholder involvement in public sector management and service delivery, it is more important than ever to rethink and redesign the structure of how policy decisions are made, implemented, monitored, and adapted to new realities. The traditional command-and-control approach is now less effective because an increasing amount of responsibility to deliver public goods and services falls on networks of nongovernment agencies. Even though public administrators are seeking new decision-making models in an increasingly more complex environment, the public sector currently only sparsely utilizes Mediated Modeling (MM). There is growing evidence, however, that by employing MM and similar tools, public interest networks can be better equipped to deal with their long-term viability while maintaining the short-term needs of their clients. However, it may require a shift in organizational culture within and between organizations to achieve the desired results. This paper explores the successes and barriers to implementing MM and similar tools in the public sector and offers insights into utilizing them through a review of case studies and interdisciplinary literature. We aim to raise a broader interest in MM and similar tools among public sector administrators at various administrative levels. We focus primarily, but not exclusively, on those cases operating at the interface of ecology and socio-economic systems. PMID:20146770

  17. Editorial article Industrial ecology in the strategic sustainable development model: strategic applications of industrial ecology

    Microsoft Academic Search

    Jouni Korhonen

    In a recent article of this journal, Robert et al. (Journal of Cleaner Production 10 (2002) 197) define five hierarchical and inter- dependent levels for a systems approach for strategic sustainable development (SSD) to move toward the desired outcome, the state of sustainability. This paper evaluates the concept of industrial ecology (IE) by considering its application and use in terms

  18. BOTTOMLAND HARDWOODS IN THE TIFTON-VIDIALIA UPLAND OF GEORGIA: A CONCEPTUAL MODEL FOR ECOLOGICAL RISK ASSESSMENT

    EPA Science Inventory

    Ecology risk assessment provides a methodology for evaluating threats to ecosystem function associated with environmental perturbations or stressors. his report documents the development of a conceptual model for assessing the ecological risk to the water quality function (WQF) o...

  19. Model Validation with Hybrid Dynamic Simulation

    SciTech Connect

    Huang, Zhenyu; Kosterev, Dmitry; Guttromson, Ross T.; Nguyen, Tony B.

    2006-06-22

    Abstract—Model validation has been one of the central topics in power engineering studies for years. As model validation aims at obtaining reasonable models to represent actual behavior of power system components, it has been essential to validate models against actual measurements or known benchmark behavior. System-wide model simulation results can be compared with actual recordings. However, it is difficult to construct a simulation case for a large power system such as the WECC system and to narrow down to problematic models in a large system. Hybrid dynamic simulation with its capability of injecting external signals into dynamic simulation enables rigorous comparison of measurements and simulation in a small subsystem of interest. This paper presents such a model validation methodology with hybrid dynamic simulation. Two application examples on generator and load model validation are presented to show the validity of this model validation methodology. This methodology is further extended for automatic model validation and dichotomous subsystem model validation. A few methods to define model quality indices have been proposed to quantify model error for model validation criteria development.

  20. On the use of remotely sensed data to constrain process modeling and ecological forecasting

    NASA Astrophysics Data System (ADS)

    Serbin, S.; Greenberg, J. A.

    2014-12-01

    The ability to seamlessly integrate information on vegetation structure, function, and dynamics across a continuum of scales, from the field to satellite observations, greatly enhances our ability to understand how terrestrial vegetation-atmosphere interactions change over time and in response?to disturbances and global change. For example, ecosystem process models require detailed information on the state (e.g. structure, leaf area index), surface properties (e.g. albedo), and dynamics (e.g. phenology, succession) of ecosystems in order to properly simulate the fluxes of carbon (C), water, and energy from the land to the atmosphere as well as address the vulnerability of ecosystems to environmental, pest and pathogen, and other anthropogenic perturbations. Other activities such as species distribution and environmental niche modeling (SDENM) require not only presence/absence information but also detailed spatial and temporal datasets, including climate and remotely sensed observations, to accurately project species ranges under current and often future climatic scenarios. Despite the many challenges of adequately initializing and parameterizing models, the last several decades have shown a substantial increase in the amount of available data useful for improving ecological predictions. Specifically remote sensing data provides an important data constraint for projecting species and successional changes as well as vegetation dynamics and the fluxes of C, water and energy and the storage of C in ecosystems, principally as a synoptic observational dataset for capturing short- to long-term plant-climate interactions. In this talk we will highlight the current and potential uses of various remotely sensed data sources in constraining process modeling and SDENM activities. We will pay particular attention to the uses of remote sensing as a direct constraint on ecological forecasts or a key observational dataset used to capture plant-climate interactions

  1. SSA Modeling and Simulation with DIRSIG

    NASA Astrophysics Data System (ADS)

    Bennett, D.; Allen, D.; Dank, J.; Gartley, M.; Tyler, D.

    2014-09-01

    We describe and demonstrate a robust, physics-based modeling system to simulate ground and space-based observations of both LEO and GEO objects. With the DIRSIG radiometry engine at its core, our system exploits STK, adaptive optics modeling, and detector effects to produce high fidelity simulated images and radiometry. Key to generating quantitative simulations is our ability to attribute engineering-quality, faceted CAD models with reflective and emissive properties derived from laboratory measurements, including the spatial structure of such difficult materials as MLI. In addition to simulated video imagery, we will demonstrate a computational procedure implementing a position-based dynamics approach to shrink wrap MLI around space components.

  2. VHDL simulation with access to transistor models

    NASA Technical Reports Server (NTRS)

    Gibson, J.

    1991-01-01

    Hardware description languages such as VHDL have evolved to aid in the design of systems with large numbers of elements and a wide range of electronic and logical abstractions. For high performance circuits, behavioral models may not be able to efficiently include enough detail to give designers confidence in a simulation's accuracy. One option is to provide a link between the VHDL environment and a transistor level simulation environment. The coupling of the Vantage Analysis Systems VHDL simulator and the NOVA simulator provides the combination of VHDL modeling and transistor modeling.

  3. Dasor, a grid model based simulation library

    Microsoft Academic Search

    Alain Bui; Olivier Flauzac

    Simulation is a key point for designing applications for large scale networks like grids or peer-to-peer networks. To be relevant, simula- tions must be computed with adequate models: communication models, fault models or network models (bandwidth, latency). In previous works, we proposed a ve layer model to map grid applications and the subja- cent network. Particularly, it shows how subjacent

  4. Modelling and simulation of large neural networks

    Microsoft Academic Search

    F. J. Lopez-Aligue; C. Garcia-Orellana; I. Acevedo-Sotoca; H. Gonzalez-Velasco; M. Macias-Macias

    1999-01-01

    We propose an object oriented model for the simulation of large neural networks using the OMTechnique. This modelling has been implemented on a client-server simulator (called NeSim-NNLIB), the server being a “beowulf” cluster, getting up to 18 MCPS with a cluster of 6 Pentium processors

  5. Crop Simulation Models and Decision Support Systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The first computer simulation models for agricultural systems were developed in the 1970s. These early models simulated potential production for major crops as a function of weather conditions, especially temperature and solar radiation. At a later stage, the water component was added to be able to ...

  6. Submarine landslide flows simulation through centrifuge modelling

    E-print Network

    Gue, Chang Shin

    2012-05-08

    SUBMARINE LANDSLIDE FLOWS SIMULATION THROUGH CENTRIFUGE MODELLING by Chang Shin GUE A dissertation submitted for the degree of Doctor of Philosophy at the University of Cambridge Churchill College January... “Continuous effort – not strength or intelligence – is the key to unlocking our potential” - Winston Churchill ABSTRACT SUBMARINE LANDSLIDE FLOWS SIMULATION THROUGH CENTRIFUGE MODELLING Chang Shin GUE Landslides occur both onshore...

  7. Monte Carlo Simulation of Interacting Electron Models

    E-print Network

    Robinson, Robert W.

    Monte Carlo Simulation of Interacting Electron Models by a New Determinant Approach by Mucheng discusses the calculation of determinants and Monte Carlo simulation of Hub- bard models by a new and a Monte Carlo summation algorithm to evaluate the relevant diagram determinant sums. Index words: Monte

  8. Population Ecology: A Simple Model of a Grasshopper Population In a text on Population Ecology, Begon (1996, p. 6) describes the life cycle of the field grasshopper

    E-print Network

    Ford, Andrew

    Population Ecology: A Simple Model of a Grasshopper Population In a text on Population Ecology, Begon (1996, p. 6) describes the life cycle of the field grasshopper (Chorthippus brunneus). The grasshopper is an annual species in which each generation lasts for just one year and there is no overlap

  9. Modelling the ecological–functional diversification of marine Metazoa on geological time scales

    PubMed Central

    Bush, Andrew M.; Novack-Gottshall, Philip M.

    2012-01-01

    The ecological traits and functional capabilities of marine animals have changed significantly since their origin in the late Precambrian. These changes can be analysed quantitatively using multi-dimensional parameter spaces in which the ecological lifestyles of species are represented by particular combinations of parameter values. Here, we present models that describe the filling of this multi-dimensional ‘ecospace’ by ecological lifestyles during metazoan diversification. These models reflect varying assumptions about the processes that drove ecological diversification; they contrast diffusive expansion with driven expansion and niche conservatism with niche partitioning. Some models highlight the importance of interactions among organisms (ecosystem engineering and predator–prey escalation) in promoting new lifestyles or eliminating existing ones. These models reflect processes that were not mutually exclusive; rigorous analyses will continue to reveal their applicability to episodes in metazoan history. PMID:21813550

  10. Modelling the ecological-functional diversification of marine Metazoa on geological time scales.

    PubMed

    Bush, Andrew M; Novack-Gottshall, Philip M

    2012-02-23

    The ecological traits and functional capabilities of marine animals have changed significantly since their origin in the late Precambrian. These changes can be analysed quantitatively using multi-dimensional parameter spaces in which the ecological lifestyles of species are represented by particular combinations of parameter values. Here, we present models that describe the filling of this multi-dimensional 'ecospace' by ecological lifestyles during metazoan diversification. These models reflect varying assumptions about the processes that drove ecological diversification; they contrast diffusive expansion with driven expansion and niche conservatism with niche partitioning. Some models highlight the importance of interactions among organisms (ecosystem engineering and predator-prey escalation) in promoting new lifestyles or eliminating existing ones. These models reflect processes that were not mutually exclusive; rigorous analyses will continue to reveal their applicability to episodes in metazoan history. PMID:21813550

  11. Guidelines for developing and updating Bayesian belief networks applied to ecological modeling and conservation1

    Microsoft Academic Search

    Bruce G. Marcot; J. Douglas Steventon; Glenn D. Sutherland; Robert K. McCann

    Bayesian belief networks (BBNs) are useful tools for modeling ecological predictions and aiding resource- management decision-making. We provide practical guidelines for developing, testing, and revising BBNs. Primary steps in this process include creating influence diagrams of the hypothesized \\

  12. STABLE ISOTOPES IN ECOLOGICAL STUDIES: NEW DEVELOPMENTS IN MIXING MODELS

    EPA Science Inventory

    Stable isotopes are increasingly being used as tracers in ecological studies. One application uses isotopic ratios to quantify the proportional contributions of multiple sources to a mixture. Examples include food sources for animals, water sources for plants, pollution sources...

  13. EPA ?s ECOLOGICAL MODELS FOR INTEGRATED WATERSHED MANAGEMENT

    EPA Science Inventory

    Aquatic ecological populations and communities are affected by the nature and quality of the water in which they live. Specific factors that affect instream biota include chemical variables, biotic interactions, energy source, flow regime, and habitat structure. As watershed mana...

  14. Integrating Edge Detection and Dynamic Modeling in Quantitative Analyses of Ecological Boundaries

    NSDL National Science Digital Library

    WILLIAM F. FAGAN, MARIE-JOSÃ?E FORTIN, and CANDAN SOYKAN (; )

    2003-08-01

    This peer-reviewed article from BioScience about quantitative analysis of ecological boundaries. Habitat boundaries profoundly influence the structure and function of landscapes, influencing ecological processes both locally and over larger scales. In addition, boundaries themselves are dynamic entities whose changes can influence diverse populations, communities, and ecosystems by way of feedback effects. These two issues, scale dependence and spatiotemporal dynamics, underlie much of the now considerable attention that modelers and statisticians have devoted to the quantitative study of ecological edges and boundaries. We present the linkages between methods of delineating boundaries, monitoring boundary changes, and modeling edge-related dynamics. In the process, we clarify statistical and mathe-matical approaches to the study of ecological edges and boundaries, and we discuss important remaining issues in the area of quantitative edge research. In particular, we address conceptual and methodological problems faced by statisticians and modelers, while highlighting topics that would benefit from a collaborative approach.

  15. Modeling and simulation of blood collection systems.

    PubMed

    Alfonso, Edgar; Xie, Xiaolan; Augusto, Vincent; Garraud, Olivier

    2012-03-01

    This paper addresses the modeling and simulation of blood collection systems in France for both fixed site and mobile blood collection with walk in whole blood donors and scheduled plasma and platelet donors. Petri net models are first proposed to precisely describe different blood collection processes, donor behaviors, their material/human resource requirements and relevant regulations. Petri net models are then enriched with quantitative modeling of donor arrivals, donor behaviors, activity times and resource capacity. Relevant performance indicators are defined. The resulting simulation models can be straightforwardly implemented with any simulation language. Numerical experiments are performed to show how the simulation models can be used to select, for different walk in donor arrival patterns, appropriate human resource planning and donor appointment strategies. PMID:22048940

  16. Ecological Niche Modelling of the Bacillus anthracis A1.a sub-lineage in Kazakhstan

    PubMed Central

    2011-01-01

    Background Bacillus anthracis, the causative agent of anthrax, is a globally distributed zoonotic pathogen that continues to be a veterinary and human health problem in Central Asia. We used a database of anthrax outbreak locations in Kazakhstan and a subset of genotyped isolates to model the geographic distribution and ecological associations of B. anthracis in Kazakhstan. The aims of the study were to test the influence of soil variables on a previous ecological niche based prediction of B. anthracis in Kazakhstan and to determine if a single sub-lineage of B. anthracis occupies a unique ecological niche. Results The addition of soil variables to the previously developed ecological niche model did not appreciably alter the limits of the predicted geographic or ecological distribution of B. anthracis in Kazakhstan. The A1.a experiment predicted the sub-lineage to be present over a larger geographic area than did the outbreak based experiment containing multiple lineages. Within the geographic area predicted to be suitable for B. anthracis by all ten best subset models, the A1.a sub-lineage was associated with a wider range of ecological tolerances than the outbreak-soil experiment. Analysis of rule types showed that logit rules predominate in the outbreak-soil experiment and range rules in the A1.a sub-lineage experiment. Random sub-setting of locality points suggests that models of B. anthracis distribution may be sensitive to sample size. Conclusions Our analysis supports careful consideration of the taxonomic resolution of data used to create ecological niche models. Further investigations into the environmental affinities of individual lineages and sub-lineages of B. anthracis will be useful in understanding the ecology of the disease at large and small scales. With model based predictions serving as approximations of disease risk, these efforts will improve the efficacy of public health interventions for anthrax prevention and control. PMID:22152056

  17. THE ECOLOGICAL CONSEQUENCES OF FLOWERING ASYNCHRONY IN MONOECIOUS FIGS: A SIMULATION STUDY

    Microsoft Academic Search

    JUDITH L. BRONSTEIN; PIERRE-HENRI GOUYON; CHRIS GLIDDON; FINN KJELLBERG; GEORGES MICHALOUD

    For plants with temporally separate sexual phases to outcross, population- level flowering asynchrony is necessary, but this can decrease the resource base available for pollinators. We developed a simulation model to examine the consequences of such asynchrony for individual reproductive success and long-term pollinator maintenance with- in monoecious fig populations. In figs, flowering is synchronous within a tree and the

  18. Simulating Runoff from a Grid Based Mercury Model: Flow Comparisons

    EPA Science Inventory

    Several mercury cycling models, including general mass balance approaches, mixed-batch reactors in streams or lakes, or regional process-based models, exist to assess the ecological exposure risks associated with anthropogenically increased atmospheric mercury (Hg) deposition, so...

  19. Computer Simulation in Chemical Kinetics

    ERIC Educational Resources Information Center

    Anderson, Jay Martin

    1976-01-01

    Discusses the use of the System Dynamics technique in simulating a chemical reaction for kinetic analysis. Also discusses the use of simulation modelling in biology, ecology, and the social sciences, where experimentation may be impractical or impossible. (MLH)

  20. Software-Engineering Process Simulation (SEPS) model

    NASA Technical Reports Server (NTRS)

    Lin, C. Y.; Abdel-Hamid, T.; Sherif, J. S.

    1992-01-01

    The Software Engineering Process Simulation (SEPS) model is described which was developed at JPL. SEPS is a dynamic simulation model of the software project development process. It uses the feedback principles of system dynamics to simulate the dynamic interactions among various software life cycle development activities and management decision making processes. The model is designed to be a planning tool to examine tradeoffs of cost, schedule, and functionality, and to test the implications of different managerial policies on a project's outcome. Furthermore, SEPS will enable software managers to gain a better understanding of the dynamics of software project development and perform postmodern assessments.

  1. Stream ecological condition modeling at the reach and the hydrologic unit (HUC) scale: A look at model performance and mapping

    EPA Science Inventory

    The National Hydrography and updated Watershed Boundary Datasets provide a ready-made framework for hydrographic modeling. Determining particular stream reaches or watersheds in poor ecological condition across large regions is an essential goal for monitoring and management. T...

  2. Pathogen survival trajectories: an eco-environmental approach to the modeling of human campylobacteriosis ecology.

    PubMed Central

    Skelly, Chris; Weinstein, Phil

    2003-01-01

    Campylobacteriosis, like many human diseases, has its own ecology in which the propagation of human infection and disease depends on pathogen survival and finding new hosts in order to replicate and sustain the pathogen population. The complexity of this process, a process common to other enteric pathogens, has hampered control efforts. Many unknowns remain, resulting in a poorly understood disease ecology. To provide structure to these unknowns and help direct further research and intervention, we propose an eco-environmental modeling approach for campylobacteriosis. This modeling approach follows the pathogen population as it moves through the environments that define the physical structure of its ecology. In this paper, we term the ecologic processes and environments through which these populations move "pathogen survival trajectories." Although such a modeling approach could have veterinary applications, our emphasis is on human campylobacteriosis and focuses on human exposures to Campylobacter through feces, food, and aquatic environments. The pathogen survival trajectories that lead to human exposure include ecologic filters that limit population size, e.g., cooking food to kill Campylobacter. Environmental factors that influence the size of the pathogen reservoirs include temperature, nutrient availability, and moisture availability during the period of time the pathogen population is moving through the environment between infected and susceptible hosts. We anticipate that the modeling approach proposed here will work symbiotically with traditional epidemiologic and microbiologic research to help guide and evaluate the acquisition of new knowledge about the ecology, eventual intervention, and control of campylobacteriosis. PMID:12515674

  3. Regional assessment of boreal forest productivity using an ecological process model and remote sensing parameter maps.

    PubMed

    Kimball, J. S.; Keyser, A. R.; Running, S. W.; Saatchi, S. S.

    2000-06-01

    An ecological process model (BIOME-BGC) was used to assess boreal forest regional net primary production (NPP) and response to short-term, year-to-year weather fluctuations based on spatially explicit, land cover and biomass maps derived by radar remote sensing, as well as soil, terrain and daily weather information. Simulations were conducted at a 30-m spatial resolution, over a 1205 km(2) portion of the BOREAS Southern Study Area of central Saskatchewan, Canada, over a 3-year period (1994-1996). Simulations of NPP for the study region were spatially and temporally complex, averaging 2.2 (+/- 0.6), 1.8 (+/- 0.5) and 1.7 (+/- 0.5) Mg C ha(-1) year(-1) for 1994, 1995 and 1996, respectively. Spatial variability of NPP was strongly controlled by the amount of aboveground biomass, particularly photosynthetic leaf area, whereas biophysical differences between broadleaf deciduous and evergreen coniferous vegetation were of secondary importance. Simulations of NPP were strongly sensitive to year-to-year variations in seasonal weather patterns, which influenced the timing of spring thaw and deciduous bud-burst. Reductions in annual NPP of approximately 17 and 22% for 1995 and 1996, respectively, were attributed to 3- and 5-week delays in spring thaw relative to 1994. Boreal forest stands with greater proportions of deciduous vegetation were more sensitive to the timing of spring thaw than evergreen coniferous stands. Similar relationships were found by comparing simulated snow depth records with 10-year records of aboveground NPP measurements obtained from biomass harvest plots within the BOREAS region. These results highlight the importance of sub-grid scale land cover complexity in controlling boreal forest regional productivity, the dynamic response of the biome to short-term interannual climate variations, and the potential implications of climate change and other large-scale disturbances. PMID:12651512

  4. Projection- vs. selection-based model reduction of complex hydro-ecological models

    NASA Astrophysics Data System (ADS)

    Galelli, S.; Giuliani, M.; Castelletti, A.; Alsahaf, A.

    2014-12-01

    Projection-based model reduction is one of the most popular approaches used for the identification of reduced-order models (emulators). It is based on the idea of sampling from the original model various values, or snapshots, of the state variables, and then using these snapshots in a projection scheme to find a lower-dimensional subspace that captures the majority of the variation of the original model. The model is then projected onto this subspace and solved, yielding a computationally efficient emulator. Yet, this approach may unnecessarily increase the complexity of the emulator, especially when only a few state variables of the original model are relevant with respect to the output of interest. This is the case of complex hydro-ecological models, which typically account for a variety of water quality processes. On the other hand, selection-based model reduction uses the information contained in the snapshots to select the state variables of the original model that are relevant with respect to the emulator's output, thus allowing for model reduction. This provides a better trade-off between fidelity and model complexity, since the irrelevant and redundant state variables are excluded from the model reduction process. In this work we address these issues by presenting an exhaustive experimental comparison between two popular projection- and selection-based methods, namely Proper Orthogonal Decomposition (POD) and Dynamic Emulation Modelling (DEMo). The comparison is performed on the reduction of DYRESM-CAEDYM, a 1D hydro-ecological model used to describe the in-reservoir water quality conditions of Tono Dam, an artificial reservoir located in western Japan. Experiments on two different output variables (i.e. chlorophyll-a concentration and release water temperature) show that DEMo allows obtaining the same fidelity as POD while reducing the number of state variables in the emulator.

  5. Assessment of ecological security in Changbai Mountain Area, China based on MODIS data and PSR model

    NASA Astrophysics Data System (ADS)

    Huang, Fang; Wang, Ping; Qi, Xin

    2014-11-01

    The assessment of ecological security is to identify the stability of the ecosystem, and to distinguish the capacity of sustainable health and integrity under different kinds of risks. Using MODIS time series images from 2000 to 2008 as the main data source, the derived parameters including NDVI, the ratio of NPP and GPP, forest coverage, landscape diversity and ecological flexibility etc. are integrated to depict the properties of the ecological system. The pressure and response indicators such as population density, industrial production intensity, arable land per capita, fertilizer consumption, highway density, agricultural mechanization level and GDP per capita are also collected and managed by ArcGIS. The `pressure-state-response' (PSR) conceptual model and a hierarchical weighted model are applied to construct an evaluation framework and determine the state of ecological security in Changbai Mountain area. The results show that the ecological security index (ESI) values in 2000 and 2008 were 5.75 and 5.59 respectively, indicating the ecological security state in Changbai Mountain area degraded. In 2000, the area of in good state of ecological security was 21901km2, occupying 28.96% of the study region. 48201 km2 of the land were with moderate level. The grades of ESI in Dunhua, Longjing and Antu decreased from moderate to poor. Though the ESI value of Meihekou increased by 0.12 during 2000-2008, it was still in a very poor state of ecological security induced by intensive human activities. The ecological security situation of Changbai Mountain region was not optimistic on the whole.

  6. Agent-based Mission Modeling and Simulation

    Microsoft Academic Search

    Maarten Sierhuis; J. Clancey; Chin Seah; Alessandro Acquisti; David Bushnell; Bruce Damer; Nancy Dorighi; Larry Edwards; Lisa Faithorn; Lorenzo Flueckiger; Ron van Hoof; Anand Nandkumar; Christian Neukom; Mike Scott; Michael Sims; Roxana Wales; Shin-Ywan Wang; James Wood

    2006-01-01

    A simulation environment for agents is presented, enabling agent-based modeling and simulation of people, systems and robots in space exploration missions. The environment allows the analysis and design of mission operation work procedures, communications and interactions between people and systems, co-located or distributed on Earth and in space. The MODAT (Mission Operations Design and Analysis Toolkit) is the integration of

  7. CAR REGISTRATION SIMULATION MODEL IN GCC COUNTRY

    Microsoft Academic Search

    Shamsuddin Ahmed

    Car registration and inspection simulation experiment to analyze business functions of the traffic department in Al-Ain city in United Arab Emirates (UAE) is reported. The car registration is managed by a government organization in association with a private network service company that looks after the inspection service. A visual AweSim car registration simulation model is developed from workflow viewpoint. The

  8. Modeling and simulation of organic solar cells

    Microsoft Academic Search

    Liming Liu; Guangyong Li

    2010-01-01

    We present our investigation of organic solar cells by modeling and simulation after numerically solving Poisson and continuity equations that describe the electric property of semiconductors. Specifically, simulations reveal that Langevin type recombination, which describes the loss mechanism in pristine materials with low mobility, is not proper to predict the performance of BHJ organic solar cells and will lead counterintuitive

  9. Modeling and simulating electronic textile applications

    Microsoft Academic Search

    Thomas Martin; Mark Jones; Joshua Edmison; Tanwir Sheikh; Zahi Nakad

    2004-01-01

    This paper describes our design of a simulation environment for electronic textiles (e-textiles) and our experiences with that environment. This simulation environment, based upon Ptolemy II, enables us to model a diverse range of areas related to the design of electronic textiles, including the physical environment they will be used in, the behavior of the sensors incorporated into the fabric,

  10. KU-Band rendezvous radar performance computer simulation model

    Microsoft Academic Search

    J. W. Griffin

    1980-01-01

    The preparation of a real time computer simulation model of the KU band rendezvous radar to be integrated into the shuttle mission simulator (SMS), the shuttle engineering simulator (SES), and the shuttle avionics integration laboratory (SAIL) simulator is described. To meet crew training requirements a radar tracking performance model, and a target modeling method were developed. The parent simulation\\/radar simulation

  11. The aircraft movement simulation model

    Microsoft Academic Search

    Michel A. Thomet

    1983-01-01

    The following paragraphs describe a computer program for simulating the movements of aircraft on the apron, taxiways, and runways of an airport. The purpose of this program is to enable the airport planner to evaluate the performance of a given airport layout from an operational point of view. Likewise, he can compare alternative layouts, investigate the impact of a change

  12. Mechanistic and ecological explanations in agent-based models of cognition

    Microsoft Academic Search

    Jason Noble; Manuel de Pinedo

    We argue that two styles of explanation—mechanistic and ecological—are needed in accounting for the behaviour of synthetic agents. An emphasis on mechanistic explanation in some current ALife models is identified, and parallels are drawn with issues in the philosophy of mind literature. We conclude that ecological or agent-level explanation does not come with representational baggage, and that mechanistic ex- planations

  13. From the Conceptual Change Model to the Productive Ecological Koinos Model: Learning that transcends

    NASA Astrophysics Data System (ADS)

    Gelpi-Rodriguez, Phaedra

    This investigation presents the analysis of a model of teaching science called the Conceptual Change Model. This model stimulates students to identify their own and alternate science concepts, and to confront these concepts with dynamic situations that will incite a conceptual change and promote their ability to master and understand the conceptual systems that serve as foundations for scientific knowledge. During a previous research made by this investigator on the Conceptual Change Model, a proposal for a new teaching model came up which she called the Productive Ecological Koinos Model. This model incorporates, among other things, the teacher's reflection and inner thoughts about the concepts taught and the learning experiences achieved in concurrence with students. Using action research, an exploration and analysis was done that focused upon how students and teachers modified their perspective of science while testing the Productive Ecological Koinos Model during the teaching-learning processes that took place in a microbiology course. The action research design allows the researcher to analyze these points from the experiential perspective, while also allowing the researcher to participate in the study. The study employed qualitative research techniques such as reflective diaries, personal profiles of participants, document analysis, audio tape recordings and transcriptions. All of these techniques are accepted within action research (Elliot, 1991). The Wolcott Model was the data analysis method used in the research. The description, analysis and interpretation carried out allowed for the examination of the various components of the Productive Ecological Koinos Model with students and teachers as to the scientific terms virus and contagion, and their experiences during the learning process within and outside the classroom. From the analysis of the Model a modification cropped up which places emphasis on conscious introspection on the learning process. This new learning model has been named the Cognitive Reflection Model. Through this Model, an analysis and introspection is made on the cognitive foundations of the scientific concept from the perspectives of the experiences of both teachers and students. It proposes, among other things, scrutiny into what could be called "Reflexive Science" for the teaching of science subjects as a result of using the Cognitive Reflection Model.

  14. Regional model simulations of New Zealand climate

    Microsoft Academic Search

    James A. Renwick; Jack J. Katzfey; Kim C. Nguyen; John L. McGregor

    1998-01-01

    Simulation of New Zealand climate is examined through the use of a regional climate model nested within the output of the Commonwealth Scientific and Industrial Research Organisation nine-level general circulation model (GCM). R21 resolution GCM output is used to drive a regional model run at 125 km grid spacing over the Australasian region. The 125 km run is used in

  15. Computer simulations and physical modelling of erosion

    E-print Network

    Franklin, W. Randolph

    Computer simulations and physical modelling of erosion C.S. Stuetzle, J. Gross, Z. Chen, B. Cutler in 2 disciplines. 2 / 10 #12;Problem and goals Validation of Erosion Models for Levee Overtopping Levee terrain, a.k.a. soil, · better modeling of local erosion in terrain and earthen structures such as levees

  16. MODELING, SIMULATION AND OPTIMIZATION OF GROUND SOURCE

    E-print Network

    MODELING, SIMULATION AND OPTIMIZATION OF GROUND SOURCE HEAT PUMP SYSTEMS By MUHAMMAD HAIDER KHAN AND OPTIMIZATION OF GROUND SOURCE HEAT PUMP SYSTEMS Thesis Approved..................................................................................................................... 1 1.1 Overview of Ground Source Heat Pump Systems.............................................. 1 1

  17. Mathematical Model Development and Simulation Support

    NASA Technical Reports Server (NTRS)

    Francis, Ronald C.; Tobbe, Patrick A.

    2000-01-01

    This report summarizes the work performed in support of the Contact Dynamics 6DOF Facility and the Flight Robotics Lab at NASA/ MSFC in the areas of Mathematical Model Development and Simulation Support.

  18. Theory, modeling, and simulation annual report, 1992

    SciTech Connect

    Not Available

    1993-05-01

    This report briefly discusses research on the following topics: development of electronic structure methods; modeling molecular processes in clusters; modeling molecular processes in solution; modeling molecular processes in separations chemistry; modeling interfacial molecular processes; modeling molecular processes in the atmosphere; methods for periodic calculations on solids; chemistry and physics of minerals; graphical user interfaces for computational chemistry codes; visualization and analysis of molecular simulations; integrated computational chemistry environment; and benchmark computations.

  19. Ecological modeling as a tool for coastal zone management in Dokai Bay, Japan

    Microsoft Academic Search

    Tetsuo Yanagi; Koh-Ichi Inoue; Sigeru Montani; Machiko Yamada

    1997-01-01

    An ecological numerical model has been developed for coastal zone management in Dokai Bay, Japan. The numerical model experiment reproduces the occurrence of red tides and oxygen-deficiency in Dokai Bay during summer. Moreover, the model experiments forecast that when the phosphorus or nitrogen load from land will be cut by 90% or 95%, respectively, red tides and oxygen-deficiency will not

  20. The construction of ecological logistics park based on network shape enterprises symbiotic relationship model

    Microsoft Academic Search

    Honglu Liu; Jiawei Zuo; Zhenji Zhang; Runtong Zhang

    2008-01-01

    Based on the idea of environmental protection, with network shape enterprise symbiotic relationship model, and make an analysis about how to establish a stable symbiotic model among enterprises in the internal logistics park. Through the analysis, regard that the construction of the ecological logistics park in that is based on the model of network shape enterprises symbiotic relationship is the

  1. Organizational Model for Cooperative and Sustaining Robotic Ecologies Eric Matson Scott DeLoach

    E-print Network

    Deloach, Scott A.

    Organizational Model for Cooperative and Sustaining Robotic Ecologies Eric Matson Scott De research deals with the development of an organizational model and implementation that allows a robotic may be human, intelligent agents or robotic. Robotic Team Formation The model for a population

  2. ECOLOGY AND BEHAVIOR Developmental Database for Phenology Models: Related Insect and

    E-print Network

    Kratochvíl, Lukas

    ECOLOGY AND BEHAVIOR Developmental Database for Phenology Models: Related Insect and Mite Species control the development of ectotherms and are used in phenology models to predict time at which of phenology models, we merged a previously published database of thermal requirements for insects, gathered

  3. Ecological Modelling 153 (2002) 131142 Temperature sensitivity of soil respiration and its effects on

    E-print Network

    Wu, Jianguo "Jingle"

    2002-01-01

    Ecological Modelling 153 (2002) 131­142 Temperature sensitivity of soil respiration and its effects of the nonlinearity in temperature sensitivity of soil respiration, several commonly used ecosystem models produce substantially different estimates of soil respiration with the same or similar model input. In this paper we

  4. Ecological Modelling 258 (2013) 101121 Contents lists available at SciVerse ScienceDirect

    E-print Network

    Arhonditsis, George B.

    2013-01-01

    Washington: A mechanistic approach to physiology in a eutrophication model Gurbir Perhara, , George B acids Zooplankton Growth limitation Stoichiometry Management-oriented models Eutrophication a b s t r and applied ecology. In this study, we enhance an existing eutrophication model with a zooplankton somatic

  5. Supervision in School Psychology: The Developmental/Ecological/Problem-Solving Model

    ERIC Educational Resources Information Center

    Simon, Dennis J.; Cruise, Tracy K.; Huber, Brenda J.; Swerdlik, Mark E.; Newman, Daniel S.

    2014-01-01

    Effective supervision models guide the supervisory relationship and supervisory tasks leading to reflective and purposeful practice. The Developmental/Ecological/Problem-Solving (DEP) Model provides a contemporary framework for supervision specific to school psychology. Designed for the school psychology internship, the DEP Model is also…

  6. Influences on Health Delivery System Satisfaction: A Partial Test of the Ecological Model

    Microsoft Academic Search

    Scott D. Moore; Kevin B. Wright; Daniel R. Bernard

    2009-01-01

    This study uses structural equation modeling to investigate several predictors of hospital system satisfaction. Drawing on Street's ecological perspective, the researchers explore several individual, provider–patient interaction, and system perceptions and expectations, test a model of hospital system satisfaction, and discuss the implications of the structural equation modeling analysis. Specifically, it was hypothesized that individuals who rated themselves as having high

  7. Studying dissolved organic carbon export from the Penobscot Watershed in to Gulf of Maine using Regional Hydro-Ecological Simulation System (RHESSys)

    NASA Astrophysics Data System (ADS)

    Rouhani, S. F. B. B.; Schaaf, C.; Douglas, E. M.; Choate, J. S.; Yang, Y.; Kim, J.

    2014-12-01

    The movement of Dissolved Organic Carbon (DOC) from terrestrial system into aquatic system plays an important role for carbon sequestration in ecosystems and affects the formation of soil organic matters.Carbon cycling, storage, and transport to marine systems have become critical issues in global-change science, especially with regard to northern latitudes (Freeman et al., 2001; Benner et al., 2004). DOC, as an important composition of the carbon cycling, leaches from the terrestrial watersheds is a large source of marine DOC. The Penobscot River basin in north-central Maine is the second largest watershed in New England, which drains in to Gulf of Maine. Approximately 89% of the watershed is forested (Griffith and Alerich, 1996).Studying temporal and spatial changes in DOC export can help us to understand terrestrial carbon cycling and to detect any shifts from carbon sink to carbon source or visa versa in northern latitude forested ecosystems.Despite for the importance of understanding carbon cycling in terrestrial and aquatic biogeochemistry, the Doc export, especially the combination of DOC production from bio-system and DOC transportation from the terrestrial in to stream has been lightly discussed in most conceptual or numerical models. The Regional Hydro-Ecological Simulation System (RHESSys), which has been successfully applied in many study sites, is a physical process based terrestrial model that has the ability to simulate both the source and transportation of DOC by combining both hydrological and ecological processes. The focus of this study is on simulating the DOC concentration and flux from the land to the water using RHESSys in the Penobscot watershed. The simulated results will be compared with field measurement of DOC from the watershed to explore the spatial and temporal DOC export pattern. This study will also enhance our knowledge to select sampling locations properly and also improve our understanding on DOC production and transportation in terrestrial forest ecosystem.

  8. Adversary Modeling and Simulation in Cyber Warfare

    Microsoft Academic Search

    Samuel N. Hamilton; Wendy L. Hamilton

    2008-01-01

    Modeling and simulation provide many excellent benefits in preparation for successful cyber operations. Whether used for creating\\u000a realistic training environments, testing new cyber warfare techniques, or predicting possible adversary actions, it is critical\\u000a for such simulations to take into account the possibility of an active cyber adversary, able to adapt its plans to network\\u000a conditions. Without realtime high fidelity modeling

  9. Application of Chebyshev polynomial to simulated modeling

    NASA Astrophysics Data System (ADS)

    Chi, Hai-Hong; Li, Dian-Pu

    2006-12-01

    Chebyshev polynomial is widely used in many fields, and used usually as function approximation in numerical calculation. In this paper, Chebyshev polynomial expression of the propeller properties across four quadrants is given at first, then the expression of Chebyshev polynomial is transformed to ordinary polynomial for the need of simulation of propeller dynamics. On the basis of it, the dynamical models of propeller across four quadrants are given. The simulation results show the efficiency of mathematical model.

  10. Verification validation and accreditation of simulation models

    Microsoft Academic Search

    Osman Balci

    1997-01-01

    This paper presents guidelines for conducting verifica- tion, validation and accreditation (VV&A) of simulation models. Fifteen guiding principles are introduced to help the researchers, practitioners and managers better com- prehend what VV&A is all about. The VV&A activities are described in the modeling and simulation life cycle. A taxonomy of more than 77 V&V techniques is provided to assist simulationists

  11. Ecology 2005 93, 431440

    E-print Network

    , phenotypic plasticity, population age, reproductive value, senescence, succession Journal of Ecology (2005. Plastic changes in seed dispersal along ecological succession: theoretical predictions from and evolutionary relevance of plastic changes in seed dispersal along ecological succession. Our model describes

  12. Indices, Graphs and Null Models: Analyzing Bipartite Ecological Networks

    Microsoft Academic Search

    Carsten F. Dormann; Jochen Frund; Nico Bluthgen; Bernd Gruber

    2009-01-01

    Many analyses of ecological networks in recent years have introduced new indices to describe network properties. As a consequence, tens of indices are available to address similar questions, differing in specific detail, sensitivity in detecting the property in question, and robustness with respect to network size and sampling intensity. Furthermore, some indices merely reflect the number of species participating in

  13. Integrated Modeling of Microbial Ecology in Subsurface Environments

    E-print Network

    and bioremediation. Finally, he will present extensions of this approach for analyzing microbial ecology species of iron-reducing bacteria critical for uranium bioremediation. Results provide an improved on bioremediation in heterogeneous environments. Frontiers in Biological Sciences Seminar Series Presents #12;

  14. Barriers and supports for female coaches: an ecological model

    Microsoft Academic Search

    Nicole M. LaVoi; Julia K. Dutove

    2012-01-01

    A vast amount of literature exists pertaining to female coaches at all levels of competition from around the globe. Within this article, using Brofenbrenner's ecological systems theory, the complex and multidimensional barriers that affect, impede or prevent females from seeking or remaining in coaching positions, in addition to factors that support and facilitate career advancement and retention, are summarized. Barriers

  15. A Rangeland Hydrology and Erosion Model for Developing Ecological Site Descriptions

    NASA Astrophysics Data System (ADS)

    Nearing, M. A.; Hernandez, M.; Armendariz, G.; Barker, S.; Williams, C. J.

    2014-12-01

    Predicting soil erosion is common practice in natural resource management for assessing the effects of management practices and control techniques of soil productivity, sediment delivery and off site water quality. The Rangeland Hydrology and Erosion Model (RHEM) was designed for this purpose. RHEM is an event-based model that estimates runoff, erosion, and sediment delivery rates and volumes at the spatial scale of the hillslope and the temporal scale of as single rainfall event. It represents erosion processes under normal and fire-impacted rangeland conditions. Moreover, it adopts a new splash erosion and thin sheet -flow transport equation developed from rangeland data, and it links the model hydrologic and erosion parameters with rangeland plant community by providing a new system of parameter estimation equations based on 204 plots at 49 rangeland sites distributed across 15 western U.S. states. Testing was done using long-term runoff and erosion data from small semi-aridland catchments. One of our goals with this project is to develop a framework for incorporating key ecohydrologic information/relationships in Ecological Site Descriptions and thereby enhanced utility of Ecological Site Descriptions s for guiding management. These key ecohydrologic relationships govern the ecologic resilience of the various states and community phases on many rangeland ecological sites and are strongly affected by management practices, land use, and disturbances. However, ecohydrologic data and relationships are often missing in Ecological Site Descriptions and resilience-based state-and-transition models. In this study we applied the RHEM model to data from multiple points in several ecological sites in Arizona, New Mexico, and Utah to assess the utility of the model for informing these Ecological Site Descriptions.

  16. Minimum-complexity helicopter simulation math model

    NASA Technical Reports Server (NTRS)

    Heffley, Robert K.; Mnich, Marc A.

    1988-01-01

    An example of a minimal complexity simulation helicopter math model is presented. Motivating factors are the computational delays, cost, and inflexibility of the very sophisticated math models now in common use. A helicopter model form is given which addresses each of these factors and provides better engineering understanding of the specific handling qualities features which are apparent to the simulator pilot. The technical approach begins with specification of features which are to be modeled, followed by a build up of individual vehicle components and definition of equations. Model matching and estimation procedures are given which enable the modeling of specific helicopters from basic data sources such as flight manuals. Checkout procedures are given which provide for total model validation. A number of possible model extensions and refinement are discussed. Math model computer programs are defined and listed.

  17. Modeling of transformers using circuit simulators

    NASA Astrophysics Data System (ADS)

    Archer, W. E.; Deveney, M. F.; Nagel, R. L.

    Transformers of two different designs, an unencapsulated pot core and an encapsulated toroidal core, have been modeled for circuit analysis with circuit simulation tools. We selected MicroSim's PSPICE and Anology's SABER as the simulation tools and used experimental BH Loop and network analyzer measurements to generate the needed input data. The models are compared for accuracy and convergence using the circuit simulators. Results are presented which demonstrate the effects on circuit performance from magnetic core losses, eddy currents, and mechanical stress on the magnetic cores.

  18. A simulation model of an insect population

    NSDL National Science Digital Library

    0000-00-00

    An insect life table simulation developed by Hein Bijlmakers. The above URL gets you to the introduction of the simulation model where various aspects of an insect population dynamics are explained. The link to the simulation brings you to the model itself with a myriad of variables including population development; egg; larval; pupal and adult mortality by parasitoids and predators amongst others. This is a great tool to investigate various aspects of insect population dynamics allowing one to investigate the impact of a number of variables on a population and may help students understand the function of insect life tables. Up to 40 generations can be iterated.

  19. Modeling and simulation of mobile satellite propagation

    NASA Technical Reports Server (NTRS)

    Barts, R. M.; Stutzman, Warren L.

    1992-01-01

    Mobile satellite systems are subject to severe fading due to blockage of the line-of-sight (LOS) path by roadside vegetation. A thorough understanding of the fading effects is necessary for the design of a reliable land mobile satellite system (LMSS). Analytical and empirical models are presented for predicting fade statistics for vegetative shadowing of mobile satellite terminals. A software simulator for generating simulated fade data is also presented. A physical model relating physical path parameters to propagation model parameters is presented, and results using the model are shown.

  20. Ecological niche modeling of sympatric krill predators around Marguerite Bay, Western Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Friedlaender, Ari S.; Johnston, David W.; Fraser, William R.; Burns, Jennifer; Halpin, Patrick N.; Costa, Daniel P.

    2011-07-01

    Adélie penguins ( Pygoscelis adeliae), carabeater seals ( Lobodon carcinophagus), humpback ( Megaptera novaeangliae), and minke whales ( Balaenoptera bonaernsis) are found in the waters surrounding the Western Antarctic Peninsula. Each species relies primarily on Antarctic krill ( Euphausia superba) and has physiological constraints and foraging behaviors that dictate their ecological niches. Understanding the degree of ecological overlap between sympatric krill predators is critical to understanding and predicting the impacts on climate-driven changes to the Antarctic marine ecosystem. To explore ecological relationships amongst sympatric krill predators, we developed ecological niche models using a maximum entropy modeling approach (Maxent) that allows the integration of data collected by a variety of means (e.g. satellite-based locations and visual observations). We created spatially explicit probability distributions for the four krill predators in fall 2001 and 2002 in conjunction with a suite of environmental variables. We find areas within Marguerite Bay with high krill predator occurrence rates or biological hot spots. We find the modeled ecological niches for Adélie penguins and crabeater seals may be affected by their physiological needs to haul-out on substrate. Thus, their distributions may be less dictated by proximity to prey and more so by physical features that over time provide adequate access to prey. Humpback and minke whales, being fully marine and having greater energetic demands, occupy ecological niches more directly proximate to prey. We also find evidence to suggest that the amount of overlap between modeled niches is relatively low, even for species with similar energetic requirements. In a rapidly changing and variable environment, our modeling work shows little indication that krill predators maintain similar ecological niches across years around Marguerite Bay. Given the amount of variability in the marine environment around the Antarctic Peninsula and how this affects the local abundance of prey, there may be consequences for krill predators with historically little niche overlap to increase the potential for interspecific competition for shared prey resources.

  1. Input modeling: input modeling techniques for discrete-event simulations

    Microsoft Academic Search

    Lawrence Leemis

    2001-01-01

    Most discrete-event simulation models have stochastic elements that mimic the probabilistic nature of the system under consideration. A close match between the input model and the true underlying probabilistic mechanism associated with the system is required for successful input modeling. The general question considered here is how to model an element (e.g., arrival process, service times) in a discrete-event simulation

  2. Developing predictive systems models to address complexity and relevance for ecological risk assessment.

    PubMed

    Forbes, Valery E; Calow, Peter

    2013-07-01

    Ecological risk assessments (ERAs) are not used as well as they could be in risk management. Part of the problem is that they often lack ecological relevance; that is, they fail to grasp necessary ecological complexities. Adding realism and complexity can be difficult and costly. We argue that predictive systems models (PSMs) can provide a way of capturing complexity and ecological relevance cost-effectively. However, addressing complexity and ecological relevance is only part of the problem. Ecological risk assessments often fail to meet the needs of risk managers by not providing assessments that relate to protection goals and by expressing risk in ratios that cannot be weighed against the costs of interventions. Once more, PSMs can be designed to provide outputs in terms of value-relevant effects that are modulated against exposure and that can provide a better basis for decision making than arbitrary ratios or threshold values. Recent developments in the modeling and its potential for implementation by risk assessors and risk managers are beginning to demonstrate how PSMs can be practically applied in risk assessment and the advantages that doing so could have. PMID:23613313

  3. Modeling & Simulation Data Analysis and Modeling & Simulation for the

    E-print Network

    and detection, data analysis and modeling form the core of the chemical-sciences contribution to the Science space using a finite-volume technique. The code uses implicit time advancement, except for the advective capabilities in a number of disciplines. Written in the "developer friendly" Java language, it enables computer

  4. Architecting a Simulation Framework for Model Rehosting

    NASA Technical Reports Server (NTRS)

    Madden, Michael M.

    2004-01-01

    The utility of vehicle math models extends beyond human-in-the-loop simulation. It is desirable to deploy a given model across a multitude of applications that target design, analysis, and research. However, the vehicle model alone represents an incomplete simulation. One must also replicate the environment models (e.g., atmosphere, gravity, terrain) to achieve identical vehicle behavior across all applications. Environment models are increasing in complexity and represent a substantial investment to re-engineer for a new application. A software component that can be rehosted in each application is one solution to the deployment problem. The component must encapsulate both the vehicle and environment models. The component must have a well-defined interface that abstracts the bulk of the logic to operate the models. This paper examines the characteristics of a rehostable modeling component from the perspective of a human-in-the-loop simulation framework. The Langley Standard Real-Time Simulation in C++ (LaSRS++) is used as an example. LaSRS++ was recently redesigned to transform its modeling package into a rehostable component.

  5. Virtual Cell modelling and simulation software environment.

    PubMed

    Moraru, I I; Schaff, J C; Slepchenko, B M; Blinov, M L; Morgan, F; Lakshminarayana, A; Gao, F; Li, Y; Loew, L M

    2008-09-01

    The Virtual Cell (VCell; http://vcell.org/) is a problem solving environment, built on a central database, for analysis, modelling and simulation of cell biological processes. VCell integrates a growing range of molecular mechanisms, including reaction kinetics, diffusion, flow, membrane transport, lateral membrane diffusion and electrophysiology, and can associate these with geometries derived from experimental microscope images. It has been developed and deployed as a web-based, distributed, client-server system, with more than a thousand world-wide users. VCell provides a separation of layers (core technologies and abstractions) representing biological models, physical mechanisms, geometry, mathematical models and numerical methods. This separation clarifies the impact of modelling decisions, assumptions and approximations. The result is a physically consistent, mathematically rigorous, spatial modelling and simulation framework. Users create biological models and VCell will automatically (i) generate the appropriate mathematical encoding for running a simulation and (ii) generate and compile the appropriate computer code. Both deterministic and stochastic algorithms are supported for describing and running non-spatial simulations; a full partial differential equation solver using the finite volume numerical algorithm is available for reaction-diffusion-advection simulations in complex cell geometries including 3D geometries derived from microscope images. Using the VCell database, models and model components can be reused and updated, as well as privately shared among collaborating groups, or published. Exchange of models with other tools is possible via import/export of SBML, CellML and MatLab formats. Furthermore, curation of models is facilitated by external database binding mechanisms for unique identification of components and by standardised annotations compliant with the MIRIAM standard. VCell is now open source, with its native model encoding language (VCML) being a public specification, which stands as the basis for a new generation of more customised, experiment-centric modelling tools using a new plug-in based platform. PMID:19045830

  6. Assessment of water ecological carrying capacity under the two policies in Tieling City on the basis of the integrated system dynamics model.

    PubMed

    Wang, Shuo; Xu, Ling; Yang, Fenglin; Wang, He

    2014-02-15

    Considering the limitation of the traditional method to assess the ecological carrying capacity and the complexity of the water ecological system, we used system dynamics, ANN, and CA-Markov to model a water ecological system. The social component was modeled according to Granger causality test by system dynamics. The natural component consists of the water resource and water environmental capacity, which were forecasted through the prediction of precipitation and change in land use cover. The interaction of the social component and the natural component mainly reflected environmental policies, such as the imposition of an environmental fee and environmental tax based on their values. Simulation results showed the different assessments on water ecological carrying capacity under the two policies. The population grew (2.9 million), and less pollution (86,632.37 t COD and 2854.5 t NH4N) was observed with the imposition of environmental tax compared with the imposition of an environmental fee (2.85 million population, 10,8381 t COD and 3543 t NH4N) at the same GDP level of 585 billion CNY in 2030. According to the causality loop, we discussed the different states under the policies and the reasons that caused the differences in water ecological carrying capacity state. According to game theory, we explained the limitation of the environmental fee policy on the basis of marginal benefit and cost. The externality was cleared up by the environmental tax policy. PMID:24361570

  7. Atmospheric model intercomparison project: Monsoon simulations

    SciTech Connect

    Sperber, K.R. [Lawrence Livermore National Lab., CA (United States). Program for Climate Model Diagnosis and Intercomparison; Palmer, T.N. [European Centre for Medium-Range Weather Forecasts, Reading (United Kingdom)

    1994-06-01

    The simulation of monsoons, in particular the Indian summer monsoon, has proven to be a critical test of a general circulation model`s ability to simulate tropical climate and variability. The Monsoon Numerical Experimentation Group has begun to address questions regarding the predictability of monsoon extremes, in particular conditions associated with El Nino and La Nina conditions that tend to be associated with drought and flood conditions over the Indian subcontinent, through a series of seasonal integrations using analyzed initial conditions from successive days in 1987 and 1988. In this paper the authors present an analysis of simulations associated with the Atmospheric Model Intercomparison Project (AMIP), a coordinated effort to simulate the 1979--1988 decade using standardized boundary conditions with approximately 30 atmospheric general circulation models. The 13 models analyzed to date are listed. Using monthly mean data from these simulations they have calculated indices of precipitation and wind shear in an effort to access the performance of the models over the course of the AMIP decade.

  8. Revolutions in energy through modeling and simulation

    SciTech Connect

    Tatro, M.; Woodard, J.

    1998-08-01

    The development and application of energy technologies for all aspects from generation to storage have improved dramatically with the advent of advanced computational tools, particularly modeling and simulation. Modeling and simulation are not new to energy technology development, and have been used extensively ever since the first commercial computers were available. However, recent advances in computing power and access have broadened the extent and use, and, through increased fidelity (i.e., accuracy) of the models due to greatly enhanced computing power, the increased reliance on modeling and simulation has shifted the balance point between modeling and experimentation. The complex nature of energy technologies has motivated researchers to use these tools to understand better performance, reliability and cost issues related to energy. The tools originated in sciences such as the strength of materials (nuclear reactor containment vessels); physics, heat transfer and fluid flow (oil production); chemistry, physics, and electronics (photovoltaics); and geosciences and fluid flow (oil exploration and reservoir storage). Other tools include mathematics, such as statistics, for assessing project risks. This paper describes a few advancements made possible by these tools and explores the benefits and costs of their use, particularly as they relate to the acceleration of energy technology development. The computational complexity ranges from basic spreadsheets to complex numerical simulations using hardware ranging from personal computers (PCs) to Cray computers. In all cases, the benefits of using modeling and simulation relate to lower risks, accelerated technology development, or lower cost projects.

  9. Biological soil crusts (biocrusts) as a model system in community, landscape and ecosystem ecology

    USGS Publications Warehouse

    Bowker, Matthew A.; Maestre, Fernando T.; Eldridge, David; Belnap, Jayne; Castillo-Monroy, Andrea; Escolar, Cristina; Soliveres, Santiago

    2014-01-01

    Model systems have had a profound influence on the development of ecological theory and general principles. Compared to alternatives, the most effective models share some combination of the following characteristics: simpler, smaller, faster, general, idiosyncratic or manipulable. We argue that biological soil crusts (biocrusts) have unique combinations of these features that should be more widely exploited in community, landscape and ecosystem ecology. In community ecology, biocrusts are elucidating the importance of biodiversity and spatial pattern for maintaining ecosystem multifunctionality due to their manipulability in experiments. Due to idiosyncrasies in their modes of facilitation and competition, biocrusts have led to new models on the interplay between environmental stress and biotic interactions and on the maintenance of biodiversity by competitive processes. Biocrusts are perhaps one of the best examples of micro-landscapes—real landscapes that are small in size. Although they exhibit varying patch heterogeneity, aggregation, connectivity and fragmentation, like macro-landscapes, they are also compatible with well-replicated experiments (unlike macro-landscapes). In ecosystem ecology, a number of studies are imposing small-scale, low cost manipulations of global change or state factors in biocrust micro-landscapes. The versatility of biocrusts to inform such disparate lines of inquiry suggests that they are an especially useful model system that can enable researchers to see ecological principles more clearly and quickly.

  10. Ecologic niche modeling and spatial patterns of disease transmission

    E-print Network

    Peterson, A. Townsend

    2006-12-01

    - ferent Chagas disease vectors in Brazil (11) and a charac- terization of ecologic features of outbreaks of hemorrhagic fever caused by Ebola and Marburg viruses (12,13). Characterizing Distributional Areas A next step in applying ENM approaches to under... or changing land use (25). This approach has seen considerable attention in the biodiversity realm, with both tests and validations (26–28), and with broad applications across faunas and floras (29–32). In the disease world, applications have been few...

  11. Using Species Distribution Models for Conservation Planning and Ecological Forecasting

    Microsoft Academic Search

    Josh J. Lawler; Yolanda F. Wiersma; Falk Huettmann

    \\u000a Conservation practitioners and resource managers must often work with limited data to answer critical, time-sensitive questions.\\u000a In many regions of the world, even the most basic information about the distribution of species is lacking. Knowing the geographic\\u000a extent of a given species or ecological system is the first step in planning for its management or conservation. The sustainable\\u000a management of

  12. Predicting the Current and Future Potential Distributions of Lymphatic Filariasis in Africa Using Maximum Entropy Ecological Niche Modelling

    PubMed Central

    Slater, Hannah; Michael, Edwin

    2012-01-01

    Modelling the spatial distributions of human parasite species is crucial to understanding the environmental determinants of infection as well as for guiding the planning of control programmes. Here, we use ecological niche modelling to map the current potential distribution of the macroparasitic disease, lymphatic filariasis (LF), in Africa, and to estimate how future changes in climate and population could affect its spread and burden across the continent. We used 508 community-specific infection presence data collated from the published literature in conjunction with five predictive environmental/climatic and demographic variables, and a maximum entropy niche modelling method to construct the first ecological niche maps describing potential distribution and burden of LF in Africa. We also ran the best-fit model against climate projections made by the HADCM3 and CCCMA models for 2050 under A2a and B2a scenarios to simulate the likely distribution of LF under future climate and population changes. We predict a broad geographic distribution of LF in Africa extending from the west to the east across the middle region of the continent, with high probabilities of occurrence in the Western Africa compared to large areas of medium probability interspersed with smaller areas of high probability in Central and Eastern Africa and in Madagascar. We uncovered complex relationships between predictor ecological niche variables and the probability of LF occurrence. We show for the first time that predicted climate change and population growth will expand both the range and risk of LF infection (and ultimately disease) in an endemic region. We estimate that populations at risk to LF may range from 543 and 804 million currently, and that this could rise to between 1.65 to 1.86 billion in the future depending on the climate scenario used and thresholds applied to signify infection presence. PMID:22359670

  13. Estimating solar radiation for plant simulation models

    SciTech Connect

    Hodges, T.; French, V.; Leduc, S.

    1985-01-01

    Five algorithms producing daily solar radiation surrogates using daily temperatures and rainfall were evaluated using measured solar radiation data for seven U.S. locations. The algorithms were compared both in terms of accuracy of daily solar radiation estimates and terms of response when used in a plant growth simulation model (CERES-wheat). Requirements for accuracy of solar radiation for plant growth simulation models are discussed. One algorithm is recommended as being best suited for use in these models when neither measured nor satellite estimated solar radiation values are available.

  14. Realistic model for battlefield fire plume simulation

    Microsoft Academic Search

    Dorothy Bruce

    1991-01-01

    Real battlefields are very messy places which may contain burning vehicles, vegetation, or buildings and with atmospheres containing dust and smoke clouds. Realistic scene simulation for system evaluation must therefore also contain these same elements. A model has been developed to generate realistic images of fire plumes from burning military vehicles. Model output includes transmittance through the plume and radiance

  15. Modeling and simulation for control design

    Microsoft Academic Search

    Eric Salter; Chris LaVigna; Mike Mattice; Mary Devito; Robert Testa

    1998-01-01

    This paper documents the use of recently developed symbolic software for modeling of a US Army M113 armoured personnel carrier and numerical simulation of the generated nonlinear ordinary differential equations of motion. A brief discussion of the symbolic software used for modeling, analysis, and control system design of multiple body systems is presented. This software is used to create a

  16. Verifying and validating a simulation model

    Microsoft Academic Search

    Anbin Hu; Ye San; Zicai Wang

    2001-01-01

    This paper presents the verification and validation (V&V) of simulation model with the emphasis on the possible modification. Based on the analysis, a new framework is proposed, and new terms are defined. An example is employed to demonstrate how the framework and terms related are used in verifying and validating an existing model.

  17. Parallel methods for the flight simulation model

    Microsoft Academic Search

    Wei Zhong Xiong; C. Swietlik

    1994-01-01

    The Advanced Computer Applications Center (ACAC) has been involved in evaluating advanced parallel architecture computers and the applicability of these machines to computer simulation models. The advanced systems investigated include parallel machines with shared. memory and distributed architectures consisting of an eight processor Alliant FX\\/8, a twenty four processor sor Sequent Symmetry, Cray XMP, IBM RISC 6000 model 550, and

  18. Modeling and simulation of film blowing process

    E-print Network

    Mayavaram, Ravisankar S.

    2005-08-29

    . In this dissertation, a transient, axisymmetric, nonisothermal, viscoelastic model is developed to simulate the process, and it is solved using finite element method. Material behavior of polymer melt is described using a modified Phan-Thien-Tanner model in the liquid...

  19. Running head: Ornstein-Uhlenbeck state-space model Ecology: in press

    E-print Network

    because such models accommodated unequal time intervals (for example, due to missing data)14 now have abundances pose challenges for analysis.2 Various statistical models for ecological time series data). The data that do exist in studies with missing data or10 unequal time intervals are potentially informative

  20. Artificial neural networks as a tool in ecological modelling, an introduction

    Microsoft Academic Search

    Sovan Lek; J. F. Guégan

    1999-01-01

    Artificial neural networks (ANNs) are non-linear mapping structures based on the function of the human brain. They have been shown to be universal and highly flexible function approximators for any data. These make powerful tools for models, especially when the underlying data relationships are unknown. In this reason, the international workshop on the applications of ANNs to ecological modelling was

  1. Ecological Modelling 185 (2005) 105131 Tropical deforestation in Madagascar: analysis using hierarchical,

    E-print Network

    Silander Jr., John A.

    2005-01-01

    Ecological Modelling 185 (2005) 105­131 Tropical deforestation in Madagascar: analysis using­effect relationships for deforestation at various scales has proven difficult even when rates of deforestation appear approach to develop a novel deforestation model for the eastern wet forested zone of Madagascar, a global

  2. INTEGRATION OF AN ECONOMY UNDER IMPERFECT COMPETITION WITH A TWELVE-CELL ECOLOGICAL MODEL

    EPA Science Inventory

    This report documents the scientific research work done to date on developing a generalized mathematical model depicting a combined economic-ecological-social system with the goal of making it available to the scientific community. The model is preliminary and has not been tested...

  3. Ecological Modelling 171 (2004) 2133 Bottom-up and top-down effects in food chains

    E-print Network

    Vermont, University of

    2004-01-01

    Ecological Modelling 171 (2004) 21­33 Bottom-up and top-down effects in food chains depend analysis of trophic-level interactions within the standard energy-based linear food-chain model, or (2) 21­33 Section 3: General analytical approach for a press-perturbed food chain. Section 4: Response

  4. A Systematic Ecological Model for Adapting Physical Activities: Theoretical Foundations and Practical Examples

    ERIC Educational Resources Information Center

    Hutzler, Yeshayahu

    2007-01-01

    This article proposes a theory- and practice-based model for adapting physical activities. The ecological frame of reference includes Dynamic and Action System Theory, World Health Organization International Classification of Function and Disability, and Adaptation Theory. A systematic model is presented addressing (a) the task objective, (b) task…

  5. Reconstruction of fire regimes through integrated paleoecological proxy data and ecological modeling

    PubMed Central

    Iglesias, Virginia; Yospin, Gabriel I.; Whitlock, Cathy

    2015-01-01

    Fire is a key ecological process affecting vegetation dynamics and land cover. The characteristic frequency, size, and intensity of fire are driven by interactions between top-down climate-driven and bottom-up fuel-related processes. Disentangling climatic from non-climatic drivers of past fire regimes is a grand challenge in Earth systems science, and a topic where both paleoecology and ecological modeling have made substantial contributions. In this manuscript, we (1) review the use of sedimentary charcoal as a fire proxy and the methods used in charcoal-based fire history reconstructions; (2) identify existing techniques for paleoecological modeling; and (3) evaluate opportunities for coupling of paleoecological and ecological modeling approaches to better understand the causes and consequences of past, present, and future fire activity. PMID:25657652

  6. Regional model simulations of New Zealand climate

    NASA Astrophysics Data System (ADS)

    Renwick, James A.; Katzfey, Jack J.; Nguyen, Kim C.; McGregor, John L.

    1998-03-01

    Simulation of New Zealand climate is examined through the use of a regional climate model nested within the output of the Commonwealth Scientific and Industrial Research Organisation nine-level general circulation model (GCM). R21 resolution GCM output is used to drive a regional model run at 125 km grid spacing over the Australasian region. The 125 km run is used in turn to drive a simulation at 50 km resolution over New Zealand. Simulations with a full seasonal cycle are performed for 10 model years. The focus is on the quality of the simulation of present-day climate, but results of a doubled-CO2 run are discussed briefly. Spatial patterns of mean simulated precipitation and surface temperatures improve markedly as horizontal resolution is increased, through the better resolution of the country's orography. However, increased horizontal resolution leads to a positive bias in precipitation. At 50 km resolution, simulated frequency distributions of daily maximum/minimum temperatures are statistically similar to those of observations at many stations, while frequency distributions of daily precipitation appear to be statistically different to those of observations at most stations. Modeled daily precipitation variability at 125 km resolution is considerably less than observed, but is comparable to, or exceeds, observed variability at 50 km resolution. The sensitivity of the simulated climate to changes in the specification of the land surface is discussed briefly. Spatial patterns of the frequency of extreme temperatures and precipitation are generally well modeled. Under a doubling of CO2, the frequency of precipitation extremes changes only slightly at most locations, while air frosts become virtually unknown except at high-elevation sites.

  7. Power electronics system modeling and simulation

    SciTech Connect

    Lai, Jih-Sheng

    1994-12-31

    This paper introduces control system design based softwares, SIMNON and MATLAB/SIMULINK, for power electronics system simulation. A complete power electronics system typically consists of a rectifier bridge along with its smoothing capacitor, an inverter, and a motor. The system components, featuring discrete or continuous, linear or nonlinear, are modeled in mathematical equations. Inverter control methods,such as pulse-width-modulation and hysteresis current control, are expressed in either computer algorithms or digital circuits. After describing component models and control methods, computer programs are then developed for complete systems simulation. Simulation results are mainly used for studying system performances, such as input and output current harmonics, torque ripples, and speed responses. Key computer programs and simulation results are demonstrated for educational purposes.

  8. Cognitive niches: an ecological model of strategy selection.

    PubMed

    Marewski, Julian N; Schooler, Lael J

    2011-07-01

    How do people select among different strategies to accomplish a given task? Across disciplines, the strategy selection problem represents a major challenge. We propose a quantitative model that predicts how selection emerges through the interplay among strategies, cognitive capacities, and the environment. This interplay carves out for each strategy a cognitive niche, that is, a limited number of situations in which the strategy can be applied, simplifying strategy selection. To illustrate our proposal, we consider selection in the context of 2 theories: the simple heuristics framework and the ACT-R (adaptive control of thought-rational) architecture of cognition. From the heuristics framework, we adopt the thesis that people make decisions by selecting from a repertoire of simple decision strategies that exploit regularities in the environment and draw on cognitive capacities, such as memory and time perception. ACT-R provides a quantitative theory of how these capacities adapt to the environment. In 14 simulations and 10 experiments, we consider the choice between strategies that operate on the accessibility of memories and those that depend on elaborate knowledge about the world. Based on Internet statistics, our model quantitatively predicts people's familiarity with and knowledge of real-world objects, the distributional characteristics of the associated speed of memory retrieval, and the cognitive niches of classic decision strategies, including those of the fluency, recognition, integration, lexicographic, and sequential-sampling heuristics. In doing so, the model specifies when people will be able to apply different strategies and how accurate, fast, and effortless people's decisions will be. PMID:21744978

  9. Development of NASA's Models and Simulations Standard

    NASA Technical Reports Server (NTRS)

    Bertch, William J.; Zang, Thomas A.; Steele, Martin J.

    2008-01-01

    From the Space Shuttle Columbia Accident Investigation, there were several NASA-wide actions that were initiated. One of these actions was to develop a standard for development, documentation, and operation of Models and Simulations. Over the course of two-and-a-half years, a team of NASA engineers, representing nine of the ten NASA Centers developed a Models and Simulation Standard to address this action. The standard consists of two parts. The first is the traditional requirements section addressing programmatics, development, documentation, verification, validation, and the reporting of results from both the M&S analysis and the examination of compliance with this standard. The second part is a scale for evaluating the credibility of model and simulation results using levels of merit associated with 8 key factors. This paper provides an historical account of the challenges faced by and the processes used in this committee-based development effort. This account provides insights into how other agencies might approach similar developments. Furthermore, we discuss some specific applications of models and simulations used to assess the impact of this standard on future model and simulation activities.

  10. Towards a coupled hydro-ecological catchment modeling approach Pt.2: water quality model

    NASA Astrophysics Data System (ADS)

    Hartwig, Melanie; Borchardt, Dietrich

    2010-05-01

    Fine sediments are a key constraint for the functions of a river. On the one hand they impact the light and heat regime and, consequently, the primary production. On the other hand they control the hydraulic connectivity of the hyporheic zone, determining residence time and oxygen availability and, hence, bio-geochemical reactions and habitat suitability. In turn, fine sediment delivery to and its fate in the aquatic system is a matter of catchment hydrology and erodability as well as transport capacity and load, respectively. This study aims to assess the influence of fine sediments on the aquatic system and the responses thereupon. The holistic modeling of fine sediment dynamics at catchment scale is challenging because of a lack of available information (input data), knowledge gaps in mathematical descriptions and the large range of spatiotemporal resolutions. In order to face these problems we approach to link distributed overland transport to in stream processes. Study site is the Kharaa river in northern Mongolia that shows a gradual degradation from pristine headwaters to disturbed lower reaches impacted by agricultural practices. Besides effects of climate change and population growth there are several pressures enhancing soil erosion from land surface or bank structures: deforestation and wildfires at headwater hill slopes, intensive grazing at floodplains, diminishing of riparian vegetation from downstream the mid reaches on and irrigated agriculture on vast stretches. Former investigations revealed deficits in benthic communities developed within the middle region and an increase in fine sediment colonisers. The part presented here concerns the water quality modeling using a compartmentalisation approach that describes the water column and sediment compartment at the same time. This is done according to the compendium described within the River Water Quality Model No.1 (RWQM1) and implemented through the AQUASIM Program for Identification and Simulation of Aquatic Systems which includes simplified submodels for sediment transport and oxygen balance. Water quality and hydraulic parameters of water column and hyporheic zone are in focus for a distinct intensive monitoring program at three different reaches along the main river course. This concept of measures contains 24 hour physicochemical measurements as well as recording of water constituents in surface and pore water (extracted via interstitial probes). Further techniques include the analysis of subsurface temperature records and freeze coring for studies on hyporheic flow as well as the examination of biomass of benthic and pelagic phytoplankton for the estimation of production and respiration parameters. Macroinvertebrates and meiofauna communities are investigated at the same time to facilitate the calibration of an ecological submodel. We expect to see effects by colmation of the upper sediment layer in dependency of space (reach) and time (hydrology). This blocking of interstices causes changes in the benthic community composition as well as it seals the lower sediment layers where oxygen depletion and anaerobic biogeochemical processes like denitrification or the mobilization of phoshorus are able to evolve.

  11. Computational Modeling for Fretting Simulation

    Microsoft Academic Search

    Yasuyuki Ishimaru; Keiji Mashimo; Kyota Susai; Yingchao Fu; Anlin Wang

    2009-01-01

    As the number of wire circuits used in automobiles increases, larger force is required to mate connectors. In order to reduce wire assembling cost, connectors with low insertion force are desired. This may, however, result in fretting problems in electric contacts of terminals. To understand the mechanism of this failure, computational modeling is believed to be beneficial. The authors have

  12. Ecological models supporting environmental decision making: a strategy for the future

    USGS Publications Warehouse

    Schmolke, Amelie; Thorbek, Pernille; DeAngelis, Donald L.; Grimm, Volker

    2010-01-01

    Ecological models are important for environmental decision support because they allow the consequences of alternative policies and management scenarios to be explored. However, current modeling practice is unsatisfactory. A literature review shows that the elements of good modeling practice have long been identified but are widely ignored. The reasons for this might include lack of involvement of decision makers, lack of incentives for modelers to follow good practice, and the use of inconsistent terminologies. As a strategy for the future, we propose a standard format for documenting models and their analyses: transparent and comprehensive ecological modeling (TRACE) documentation. This standard format will disclose all parts of the modeling process to scrutiny and make modeling itself more efficient and coherent.

  13. Entomopathogenic Nematodes as a Model System for Advancing the Frontiers of Ecology

    PubMed Central

    Campos–Herrera, Raquel; Barbercheck, Mary; Hoy, Casey W.; Stock, S. Patricia

    2012-01-01

    Entomopathogenic nematodes (EPNs) in the families Heterorhabditidae and Steinernematidae have a mutualistic–symbiotic association with enteric ?-Proteobacteria (Steinernema–Xenorhabdus and Heterorhabditis–Photorhabdus), which confer high virulence against insects. EPNs have been studied intensively because of their role as a natural mortality factor for soil-dwelling arthropods and their potential as biological control agents for belowground insect pests. For many decades, research on EPNs focused on the taxonomy, phylogeny, biogeography, genetics, physiology, biochemistry and ecology, as well as commercial production and application technologies. More recently, EPNs and their bacterial symbionts are being viewed as a model system for advancing research in other disciplines such as soil ecology, symbiosis and evolutionary biology. Integration of existing information, particularly the accumulating information on their biology, into increasingly detailed population models is critical to improving our ability to exploit and manage EPNs as a biological control agent and to understand ecological processes in a changing world. Here, we summarize some recent advances in phylogeny, systematics, biogeography, community ecology and population dynamics models of EPNs, and describe how this research is advancing frontiers in ecology. PMID:23482825

  14. Plasma disruption modeling and simulation

    SciTech Connect

    Hassanein, A. [Argonne National Lab., IL (United States)

    1994-11-01

    Disruptions in tokamak reactors are considered a limiting factor to successful operation and reliable design. The behavior of plasma-facing components during a disruption is critical to the overall integrity of the reactor. Erosion of plasma facing-material (PFM) surfaces due to thermal energy dump during the disruption can severely limit the lifetime of these components and thus diminish the economic feasibility of the reactor. A comprehensive understanding of the interplay of various physical processes during a disruption is essential for determining component lifetime and potentially improving the performance of such components. There are three principal stages in modeling the behavior of PFM during a disruption. Initially, the incident plasma particles will deposit their energy directly on the PFM surface, heating it to a very high temperature where ablation occurs. Models for plasma-material interactions have been developed and used to predict material thermal evolution during the disruption. Within a few microseconds after the start of the disruption, enough material is vaporized to intercept most of the incoming plasma particles. Models for plasma-vapor interactions are necessary to predict vapor cloud expansion and hydrodynamics. Continuous heating of the vapor cloud above the material surface by the incident plasma particles will excite, ionize, and cause vapor atoms to emit thermal radiation. Accurate models for radiation transport in the vapor are essential for calculating the net radiated flux to the material surface which determines the final erosion thickness and consequently component lifetime. A comprehensive model that takes into account various stages of plasma-material interaction has been developed and used to predict erosion rates during reactor disruption, as well during induced disruption in laboratory experiments.

  15. Equivalent drawbead models for sheet forming simulation

    Microsoft Academic Search

    S. J. Moon; M. G. Lee; S. H. Lee; Y. T. Keum

    2010-01-01

    Equivalent drawbead models associated with drawbead types, with which the geometrical modeling of drawbeads can be replaced\\u000a in a numerical simulation of the stamping process, are introduced. The accuracy of the equivalent drawbead models rapidly\\u000a computing the drawbead restraining and opening forces, based on the hybrid membrane\\/bending method accommodating Barlat’s\\u000a anisotropic yield function for the plane stress state and the

  16. Blast furnace on-line simulation model

    Microsoft Academic Search

    Henrik Saxén

    1990-01-01

    A mathematical model of the ironmaking blast furnace (BF) is presented. The model describes the steady-state operation of\\u000a the furnace in one spatial dimension using real process data sampled at the steelworks. The measurement data are reconciled\\u000a by an interface routine which yields boundary conditions obeying the conservation laws of atoms and energy. The simulation\\u000a model, which provides a picture

  17. [Calculation model of urban water resources ecological footprint and its application: a case study in Shenyang City of Northeast China].

    PubMed

    Wang, Jian; Zhang, Chao-Xing; Yu, Ying-Tan; Li, Fa-Yun; Ma, Fang

    2012-08-01

    Water resources ecological footprint can directly reflect the pressure of human social and economic activities to water resources, and provide important reference for the rational utilization of water resources. Based on the existing ecological footprint models and giving full consideration of the water resources need of urban ecological system, this paper established a new calculation model of urban water resources ecological footprint, including domestic water account, process water account, public service water account, and ecological water requirement account. According to the actual situation of Shenyang City, the key parameters of the model were determined, and the water resources ecological footprint and ecological carrying capacity of the City were calculated and analyzed. From 2000 to 2009, the water resources ecological footprint per capita of the City presented an overall decreasing trend, but still had an annual ecological deficit. As compared to that in 2000, the water resources ecological footprint per capita was decreased to 0.31 hm2 in 2005, increased slightly in 2006 and 2007, and remained stable in 2008 and 2009, which suggested that the sustainable utilization of water resources in Shenyang City had definite improvement, but was still in an unsustainable development situation. PMID:23189707

  18. Incorporation of RAM techniques into simulation modeling

    NASA Astrophysics Data System (ADS)

    Nelson, S. C., Jr.; Haire, M. J.; Schryver, J. C.

    1995-01-01

    This work concludes that reliability, availability, and maintainability (RAM) analytical techniques can be incorporated into computer network simulation modeling to yield an important new analytical tool. This paper describes the incorporation of failure and repair information into network simulation to build a stochastic computer model to represent the RAM Performance of two vehicles being developed for the US Army: The Advanced Field Artillery System (AFAS) and the Future Armored Resupply Vehicle (FARV). The AFAS is the US Army's next generation self-propelled cannon artillery system. The FARV is a resupply vehicle for the AFAS. Both vehicles utilize automation technologies to improve the operational performance of the vehicles and reduce manpower. The network simulation model used in this work is task based. The model programmed in this application requirements a typical battle mission and the failures and repairs that occur during that battle. Each task that the FARV performs--upload, travel to the AFAS, refuel, perform tactical/survivability moves, return to logistic resupply, etc.--is modeled. Such a model reproduces a model reproduces operational phenomena (e.g., failures and repairs) that are likely to occur in actual performance. Simulation tasks are modeled as discrete chronological steps; after the completion of each task decisions are programmed that determine the next path to be followed. The result is a complex logic diagram or network. The network simulation model is developed within a hierarchy of vehicle systems, subsystems, and equipment and includes failure management subnetworks. RAM information and other performance measures are collected which have impact on design requirements. Design changes are evaluated through 'what if' questions, sensitivity studies, and battle scenario changes.

  19. Incorporation of RAM techniques into simulation modeling

    SciTech Connect

    Nelson, S.C. Jr.; Haire, M.J.; Schryver, J.C.

    1995-07-01

    This work concludes that reliability, availability, and maintainability (RAM) analytical techniques can be incorporated into computer network simulation modeling to yield an important new analytical tool. This paper describes the incorporation of failure and repair information into network simulation to build a stochastic computer model represents the RAM Performance of two vehicles being developed for the US Army: The Advanced Field Artillery System (AFAS) and the Future Armored Resupply Vehicle (FARV). The AFAS is the US Army`s next generation self-propelled cannon artillery system. The FARV is a resupply vehicle for the AFAS. Both vehicles utilize automation technologies to improve the operational performance of the vehicles and reduce manpower. The network simulation model used in this work is task based. The model programmed in this application requirements a typical battle mission and the failures and repairs that occur during that battle. Each task that the FARV performs--upload, travel to the AFAS, refuel, perform tactical/survivability moves, return to logistic resupply, etc.--is modeled. Such a model reproduces a model reproduces operational phenomena (e.g., failures and repairs) that are likely to occur in actual performance. Simulation tasks are modeled as discrete chronological steps; after the completion of each task decisions are programmed that determine the next path to be followed. The result is a complex logic diagram or network. The network simulation model is developed within a hierarchy of vehicle systems, subsystems, and equipment and includes failure management subnetworks. RAM information and other performance measures are collected which have impact on design requirements. Design changes are evaluated through ``what if`` questions, sensitivity studies, and battle scenario changes.

  20. Toward the Quantification of a Conceptual Framework for Movement Ecology Using Circular Statistical Modeling

    PubMed Central

    Shimatani, Ichiro Ken; Yoda, Ken; Katsumata, Nobuhiro; Sato, Katsufumi

    2012-01-01

    To analyze an animal’s movement trajectory, a basic model is required that satisfies the following conditions: the model must have an ecological basis and the parameters used in the model must have ecological interpretations, a broad range of movement patterns can be explained by that model, and equations and probability distributions in the model should be mathematically tractable. Random walk models used in previous studies do not necessarily satisfy these requirements, partly because movement trajectories are often more oriented or tortuous than expected from the models. By improving the modeling for turning angles, this study aims to propose a basic movement model. On the basis of the recently developed circular auto-regressive model, we introduced a new movement model and extended its applicability to capture the asymmetric effects of external factors such as wind. The model was applied to GPS trajectories of a seabird (Calonectris leucomelas) to demonstrate its applicability to various movement patterns and to explain how the model parameters are ecologically interpreted under a general conceptual framework for movement ecology. Although it is based on a simple extension of a generalized linear model to circular variables, the proposed model enables us to evaluate the effects of external factors on movement separately from the animal’s internal state. For example, maximum likelihood estimates and model selection suggested that in one homing flight section, the seabird intended to fly toward the island, but misjudged its navigation and was driven off-course by strong winds, while in the subsequent flight section, the seabird reset the focal direction, navigated the flight under strong wind conditions, and succeeded in approaching the island. PMID:23226261

  1. Toward an Ecological Economics

    Microsoft Academic Search

    J. R. Stanfield; HERMAN E. DALY

    1983-01-01

    Costanza, R. and Daly, H.E., 1987. Toward an ecological economics. Ecol. Modelling, 38: 1-7. Integrating ecology and economics is increasingly important as humanity's impact on the natural world increases. Current paradigms in both fields are too narrow (and seem to be getting narrower). This paper introduces and summarizes this special issue of Ecological Modeling devoted to ecological economics. There are

  2. Common modeling system for digital simulation

    NASA Technical Reports Server (NTRS)

    Painter, Rick

    1994-01-01

    The Joint Modeling and Simulation System is a tri-service investigation into a common modeling framework for the development digital models. The basis for the success of this framework is an X-window-based, open systems architecture, object-based/oriented methodology, standard interface approach to digital model construction, configuration, execution, and post processing. For years Department of Defense (DOD) agencies have produced various weapon systems/technologies and typically digital representations of the systems/technologies. These digital representations (models) have also been developed for other reasons such as studies and analysis, Cost Effectiveness Analysis (COEA) tradeoffs, etc. Unfortunately, there have been no Modeling and Simulation (M&S) standards, guidelines, or efforts towards commonality in DOD M&S. The typical scenario is an organization hires a contractor to build hardware and in doing so an digital model may be constructed. Until recently, this model was not even obtained by the organization. Even if it was procured, it was on a unique platform, in a unique language, with unique interfaces, and, with the result being UNIQUE maintenance required. Additionally, the constructors of the model expended more effort in writing the 'infrastructure' of the model/simulation (e.g. user interface, database/database management system, data journalizing/archiving, graphical presentations, environment characteristics, other components in the simulation, etc.) than in producing the model of the desired system. Other side effects include: duplication of efforts; varying assumptions; lack of credibility/validation; and decentralization in policy and execution. J-MASS provides the infrastructure, standards, toolset, and architecture to permit M&S developers and analysts to concentrate on the their area of interest.

  3. Simulation analysis: applications of discrete event simulation modeling to military problems

    Microsoft Academic Search

    Raymond R. Hill; John O. Miller; Gregory A. McIntyre

    2001-01-01

    The military is a big user of discrete event simulation models. The use of these models range from training and wargaming their constructive use in important military analyses. In this paper we discuss the uses of military simulation, the issues associated with military simulation to include categorizations of various types of military simulation. We then discuss three particular simulation studies

  4. Abstracts and program proceedings of the 1994 meeting of the International Society for Ecological Modelling North American Chapter

    SciTech Connect

    Kercher, J.R.

    1994-06-01

    This document contains information about the 1994 meeting of the International Society for Ecological Modelling North American Chapter. The topics discussed include: extinction risk assessment modelling, ecological risk analysis of uranium mining, impacts of pesticides, demography, habitats, atmospheric deposition, and climate change.

  5. Application of ecological modelling to investigate the impact of domestic waste water to one natural river system in tropical area (the nhue river, outskirts of hanoi, vietnam)

    NASA Astrophysics Data System (ADS)

    Trinh Anh, D.; Bonnet, M. P.; Prieur, N.

    2003-04-01

    Water quality modelling has been employed as an effective tool to investigate the ecological situation of surface water sources. Within a researching collaboration of Vietnamese and French scientists, one portion, 40 km, of the Nhue river, outskirts of Hanoi city, northern Vietnam, has been investigated since the river has been highly impacted from anthropogenic activities and one 1-D ecological river model was formed based on the investigation. In this paper, biochemical process equations integrated with hydraulic conditions and human alterations are presented as the basis for ecological variation of this river system. Investigation showed that at the origin the river water remains untouched (nutrients are low in natural tropical water) while downstream the river is full of domestic pollutants (organic materials and nutrients). From the hydraulic, biological, chemical data and fieldwork experiments, the sensitivity analysis and parameter estimation have been carried out to verify the biochemical processes and optimise this model. Most calculations (simulation, sensitivity functions and parameter estimation) were performed with AQUASIM, a computer program designed for simulation and data analysis of 1-D river and other aquatic systems. The other supporting calculations for system analysis were implemented with IDENT based on output of a sensitivity analysis carried out with AQUASIM. The simulation results accomplished with available data indicate that the sediment exchanges and biodegradation processes emerge as the most important features that influence the water quality of the river where water is usually overloaded by domestic wastewater and where hydraulic characters are less pronounced. The model construction and simulation results have also pointed out that the river water quality has been spoiled dramatically after the main open-air sewer of the Hanoi city, the To Lich river, excesses to the Nhue. Beside, a metal speciation module was proposed to integrate with existing biochemical model in order to simulate the metal fractions in water column and metal exchange between river water and sediment.

  6. Modeling surgical skill learning with cognitive simulation.

    PubMed

    Park, Shi-Hyun; Suh, Irene H; Chien, Jung-hung; Paik, Jaehyon; Ritter, Frank E; Oleynikov, Dmitry; Siu, Ka-Chun

    2011-01-01

    We used a cognitive architecture (ACT-R) to explore the procedural learning of surgical tasks and then to understand the process of perceptual motor learning and skill decay in surgical skill performance. The ACT-R cognitive model simulates declarative memory processes during motor learning. In this ongoing study, four surgical tasks (bimanual carrying, peg transfer, needle passing, and suture tying) were performed using the da Vinci© surgical system. Preliminary results revealed that an ACT-R model produced similar learning effects. Cognitive simulation can be used to demonstrate and optimize the perceptual motor learning and skill decay in surgical skill training. PMID:21335834

  7. Ecological impact in ditch mesocosms of simulated spray drift from a crop protection program for potatoes.

    PubMed

    Arts, Gertie H P; Buijse-Bogdan, Laura L; Belgers, J Dick M; van Rhenen-Kersten, Caroline H; van Wijngaarden, Rene P A; Roessink, Ivo; Maund, Steve J; van den Brink, Paul J; Brockt, Theo C M

    2006-04-01

    Outdoor aquatic ditch mesocosms were treated with a range of pesticides to simulate various spray drift rates resulting from a typical crop protection program used in the cultivation of potatoes in The Netherlands. The main experimental aims of the present study were to provide information on the fate and ecological effects of drift of the pesticides into surface water and to evaluate the effectiveness of drift-reduction measures in mitigating risks. The pesticides selected and the dosage, frequency, and timing of application were based on normal agricultural practices in the potato crop. Applications of prosulfocarb, metribuzin (both herbicides), lambda-cyhalothrin (insecticide), chlorothalonil, and fluazinam (both fungicides) were made in the sequence typical of the spray calendar for potatoes. A total of 15 treatments with the various compounds were made by spray application to the water surface at 0.2%, 1%, and 5% of the recommended label rates. Chemical fate and effects on ecosystem function and structure (phytoplankton, zooplankton, chlorophyll-a, macroinvertebrates, macrophytes, breakdown of plant litter) were investigated. To interpret the observed effects, treatment concentrations were also expressed in toxic units (TU), which describe the relative toxicity of the compounds with standard toxicity test organisms (Daphnia and algae). After treatment, each compound disappeared from the water phase within 2 d, with the exception of prosulfocarb, for which 50% dissipation time (DT50) values ranged between 6 and 7 d. At the 5% treatment level, an exposure peak of 0.9 TUalgae was observed, which resulted in short-term responses of pH, oxygen, and phytoplankton. At the 5% treatment level, exposure concentrations also exceeded 0.1 TUDaphnia, and this resulted in long-term effects on zooplankton and macroinvertebrates, some of which did not fully recover by the end of the present study. At the 1% treatment level, only slight transient effects were observed on a limited number of zooplankton and macro-invertebrate species and on pH. At the 0.2% level, no consistent treatment-related effects were observed. Most of the observed effects were consistent with the results from higher-tier and mesocosm studies with the individual compounds. Multi and repeated stress played a small role within the applied pesticide package, because of rapid dissipation of most substances and the absence of many simultaneous applications. This suggests that risk assessments based on the individual compounds would in this case have been sufficiently protective for their uses in a crop protection program. PMID:16646380

  8. Simulated annealing for generalized Skyrme models

    NASA Astrophysics Data System (ADS)

    Longpré, J.-P.; Marleau, L.

    2005-05-01

    We use a simulated annealing algorithm to find the static field configuration with the lowest energy in a given sector of topological charge for generalized SU(2) Skyrme models. These numerical results suggest that the following conjecture may hold: the symmetries of the soliton solutions of extended Skyrme models are the same as for the Skyrme model. Indeed, this is verified for two effective Lagrangians with terms of order six and order eight in derivatives of the pion fields, respectively, for topological charges B=1 up to B=4. We also evaluate the energy of these multiskyrmions using the rational maps ansatz. A comparison with the exact numerical results shows that the reliability of this approximation for extended Skyrme models is almost as good as for the pure Skyrme model. Some details regarding the implementation of the simulated annealing algorithm in one and three spatial dimensions are provided.

  9. Ecological Niche Model used to examine the distribution of an invasive, non-indigenous coral.

    PubMed

    Carlos-Júnior, L A; Barbosa, N P U; Moulton, T P; Creed, J C

    2015-02-01

    All organisms have a set of ecological conditions (or niche) which they depend on to survive and establish in a given habitat. The ecological niche of a species limits its geographical distribution. In the particular case of non-indigenous species (NIS), the ecological requirements of the species impose boundaries on the potential distribution of the organism in the new receptor regions. This is a theoretical assumption implicit when Ecological Niche Models (ENMs) are used to assess the potential distribution of NIS. This assumption has been questioned, given that in some cases niche shift may occur during the process of invasion. We used ENMs to investigate whether the model fit with data from the native range of the coral Tubastraea coccinea Lesson, 1829 successfully predicts its invasion in the Atlantic. We also identified which factors best explain the distribution of this NIS. The broad native distributional range of T. coccinea predicted the invaded sites well, especially along the Brazilian coast, the Caribbean Sea and Gulf of Mexico. The occurrence of T. coccinea was positively related to calcite levels and negatively to eutrophy, but was rather unaffected to other variables that often limit other marine organisms, suggesting that this NIS has wide ecological limits, a trait typical of invasive species. PMID:25465286

  10. Experimental Noise Injection in Simulated Model Signals

    NASA Astrophysics Data System (ADS)

    Khan, Tariq; Udpa, Lalita; Udpa, Satish

    2011-06-01

    Nondestructive testing methods have been routinely, designed, evaluated and optimized using simulation models developed using various computational techniques. The simulated signal using computational model differs from the true signal in that the signal does not simulated experimental noise. In order to use the computational models more effectively for signal processing algorithm development, experimental noise should be injected in the simulated signals. Experimental noise PDF (probability density function) can be numerically calculated from measured noise. The experimental signal PDF can then be generated by combining the simulation signal and measurement noise PDF. Sampling from experimental signal distribution is not a straight forward task as the distribution is generally not a standard parametric distribution. This paper presents a method that approximates experimental signal PDF as a mixture of Gaussian densities. Maximum-likelihood estimate of the parameters of Gaussian distributions from a given data set are computed using expectation-maximization (EM) technique. A sampling scheme from the mixture of Gaussian densities is also discussed. The overall algorithm is implemented on eddy current inspection data from steam generator (SG) tubing.

  11. Learning Causal Models via Progressive Alignment & Qualitative Modeling: A Simulation

    Microsoft Academic Search

    Scott E. Friedman; Kenneth D. Forbus

    Learning causal models is one of the central problems of cognitive science. We describe a simulation of early learning in physical domains from observations that uses progressive alignment and qualitative modeling to derive plausible causal models from observations. We show how protohistories can be created via progressive alignment and used with covariance algorithms to infer causality. The result, a causal

  12. Applications of discrete event simulation modeling to military problems

    Microsoft Academic Search

    Raymond R. Hill; J. O. Miller; Gregory A. McIntyre

    2001-01-01

    The military is a big user of discrete event simulation models. The use of these models range from training and wargaming their constructive use in important military analyses. In this paper we discuss the uses of military simulation, the issues associated with military simulation to include categorizations of various types of military simulation. We then discuss three particular simulation studies

  13. Gnie mcanique Thermal Modelling And Correlation of a Comet Simulation

    E-print Network

    Candea, George

    of future investigations on comet CG by the ESA Rosetta mission. A thermal model of the simulation chamberSECTION DE Génie mécanique Thermal Modelling And Correlation of a Comet Simulation Facility Author Thomas Beck André Bieler Why simulating comets? The comet simulation facility SCITEAS (Simulation Chamber

  14. USING STRUCTURAL EQUATION MODELING TO INVESTIGATE RELATIONSHIPS AMONG ECOLOGICAL VARIABLES

    EPA Science Inventory

    This paper gives an introductory account of Structural Equation Modeling (SEM) and demonstrates its application using LISREL< with a model utilizing environmental data. Using nine EMAP data variables, we analyzed their correlation matrix with an SEM model. The model characterized...

  15. WATER SUPPLY SIMULATION MODEL. VOLUME 3. DOCUMENTATION

    EPA Science Inventory

    This three-volume report describes the development of a water supply simulation model (WSSM), a system of computer programs that allows for a systematic evaluation of the physical and economic characteristics of a water distribution system in a spatial framework. The WSSM concept...

  16. TIRE MODELS IN AIRCRAFT LANDING GEAR SIMULATION

    Microsoft Academic Search

    M. T. P. van Slagmaat

    1992-01-01

    This report discusses the development of a simulation model of an aircraft landing gear describing its typical non-linear behaviour. The development of the design tool -which correlates the actual design parameters with the performance of the gear- is a part of the research project that investigates the estimation of the nonlinear dynamical system, which an aircraft landing gear is. This

  17. Modeling and Simulation for Flexible Ureteroscopy

    E-print Network

    Janardan, Ravi

    patient-specific calyceal anatomy, identifying stone size and location, and scope selection a combination of physical and virtual prototyping in 3D. Specifically, 3D-printing techniques are used to facilitate simulation studies and interaction with a virtual model. Conclusion The development of a patient

  18. Models, Simulations, and Games: A Survey.

    ERIC Educational Resources Information Center

    Shubik, Martin; Brewer, Garry D.

    A Rand evaluation of activity and products of gaming, model-building, and simulation carried out under the auspices of the Defense Advanced Research Projects Agency aimed not only to assess the usefulness of gaming in military-political policymaking, but also to contribute to the definition of common standards and the refinement of objectives for…

  19. Center for Advanced Modeling and Simulation Intern

    SciTech Connect

    Gertman, Vanessa

    2010-01-01

    Some interns just copy papers and seal envelopes. Not at INL! Check out how Vanessa Gertman, an INL intern working at the Center for Advanced Modeling and Simulation, spent her summer working with some intense visualization software. Lots more content like this is available at INL's facebook page http://www.facebook.com/idahonationallaboratory.

  20. Biological Invasion: Observations, Theory, Models, Simulations

    E-print Network

    Biological Invasion: Observations, Theory, Models, Simulations Sergei Petrovskii Department;Introduction: What it is all about The term biological invasion is a common name for a variety of phenomena invasionStages of biological invasion. (a) Introduction of an alien species: (b) Establishment

  1. Modelling and Simulation in Aerodynamic Design

    E-print Network

    Mosegaard, Klaus

    Modelling and Simulation in Aerodynamic Design In different kinds of aerodynamic design elements is too complex. Aerodynamic properties of different airfoils are found from either numerical turbine blade, two design features are important. The aerodynamic design attempts to optimize the blade

  2. Optoelectronic Device Modeling Using Field Simulation Techniques

    Microsoft Academic Search

    Minya Zhang

    1998-01-01

    Optoelectronic devices are important devices in optical fiber communications, optical signal processing, and optoelectronic equipment. This thesis develops new models for optoelectronic devices using electromagnetic field simulation techniques. To demonstrate this new technique, two kinds of optoelectronic devices are investigated in this thesis. Vertical cavity surface emitting laseer (VCSEL) is taken as the first research example due to the promising

  3. Optoelectronic device modeling using field simulation techniques

    Microsoft Academic Search

    Minya Zhang

    1998-01-01

    Optoelectronic devices are important devices in optical fiber communications, optical signal processing, and optoelectronic equipment. This thesis develops new models for optoelectronic devices using electromagnetic field simulation techniques. ^ To demonstrate this new technique, two kinds of optoelectronic devices are investigated in this thesis. Vertical cavity surface emitting laser (VCSEL) is taken as the first research example due to the

  4. Theory, Modeling and Simulation Annual Report 2000

    Microsoft Academic Search

    David A Dixon; Bruce C Garrett; TP Straatsma; Donald R Jones; Scott Studham; Robert J Harrison; Jeffrey A Nichols

    2001-01-01

    This annual report describes the 2000 research accomplishments for the Theory, Modeling, and Simulation (TM and S) directorate, one of the six research organizations in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) at Pacific Northwest National Laboratory (PNNL). EMSL is a U.S. Department of Energy (DOE) national scientific user facility and is the centerpiece of the DOE commitment

  5. Theory, Modeling and Simulation Annual Report 2000

    Microsoft Academic Search

    David A. Dixon; Bruce C. Garrett; Tp Straatsma; Donald R. Jones; Ronald S. Studham; Robert J. Harrison; Jeffrey A. Nichols

    2001-01-01

    This annual report describes the 2000 research accomplishments for the Theory, Modeling, and Simulation (TM&S) directorate, one of the six research organizations in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) at Pacific Northwest National Laboratory (PNNL). EMSL is a U.S. Department of Energy (DOE) national scientific user facility and is the centerpiece of the DOE commitment to providing

  6. Love Kills:. Simulations in Penna Ageing Model

    NASA Astrophysics Data System (ADS)

    Stauffer, Dietrich; Cebrat, Stanis?aw; Penna, T. J. P.; Sousa, A. O.

    The standard Penna ageing model with sexual reproduction is enlarged by adding additional bit-strings for love: Marriage happens only if the male love strings are sufficiently different from the female ones. We simulate at what level of required difference the population dies out.

  7. VARIANCE REDUCTION IN SIMULATIONS OF LOSS MODELS

    E-print Network

    Srikant, Rayadurgam

    VARIANCE REDUCTION IN SIMULATIONS OF LOSS MODELS by Rayadurgam Srikant 1 and Ward Whitt 2 October). The variance reduction is often dramatic when the blocking probability is high and the service times are highly component estimators are very unequal, the variance reduction from the optimal convex combination is about 1

  8. VARIANCE REDUCTION IN SIMULATIONS OF LOSS MODELS

    Microsoft Academic Search

    Rayadurgam Srikant; Ward Whitt

    1995-01-01

    We propose a new estimator of steady-state blocking probabilities for simulations of stochasticloss models that can be much more e#cient than the natural estimator (ratio of losses to arrivals).The proposed estimator is a convex combination of the natural estimator and an indirect estimatorbased on the average number of customers in service, obtained from Little's law (L = #W ). Itexploits

  9. Modeling and Simulation Information Analysis Center

    NSDL National Science Digital Library

    The Modeling and Simulation Information Analysis Center (MSIAC) assists the Department of Defense (DoD) in meeting its M&S needs "by providing scientific, technical, and operational support information and services." Through the Help Desk, MSIAC also answers technical inquiries from non-DoD customers, who agree to pay for their service beyond the first two hours. The group has experience in weapons technology including WMD, information management, modeling and simulation, operations analysis, chemical and explosive sciences, material sciences, spectrum engineering, wireless communication, life sciences, medical informatics and telemedicine, transportation systems, and reliability, availability, and maintainability. A wealth of resources are available from this website, including the Modeling & Simulation Resource Repository (MSRR), which is described as "the first place to go for answers to M&S" and Glossary of Modeling and Simulation (M&S) Terms, information on special topics of interest within M&S, and links to related websites. The MSIAC's M&S Journal Online offers quarterly articles of interest to the M&S community free of charge. This site is also reviewed in the March 25, 2005_NSDL MET Report_.

  10. A simulation model for Dynamic File Management

    Microsoft Academic Search

    Lawrence L. Rose; Malcolm A. Gotterer; Jack C. Hayya

    1974-01-01

    This paper describes a FORTRAN simulation program written to carry out Dynamic File Management (DFM) strategies. The DFM model provides effective management of secondary storage while enhancing throughput time. The main problems we address are: how data is moved from level to level; the determination of criteria to justify file movement; and the implications of implementing the DFM techniques. It

  11. Evaluating presence-absence models in ecology: the need to account for prevalence

    Microsoft Academic Search

    STÉPHANIE MANEL; H. CERI WILLIAMS; S. J. ORMEROD

    2001-01-01

    Summary 1. Models for predicting the distribution of organisms from environmental data are widespread in ecology and conservation biology. Their performance is invariably evalu- ated from the percentage success at predicting occurrence at test locations. 2. Using logistic regression with real data from 34 families of aquatic invertebrates in 180 Himalayan streams, we illustrate how this widespread measure of predictive

  12. UNIVERSITY OF CALIFORNIA A STOCHASTIC DYNAMIC MODEL OF THE BEHAVIORAL ECOLOGY OF

    E-print Network

    Mangel, Marc

    of play behavior are learned or experimental in nature) (v) Play only occurs in a stress free environment. UNIVERSITY OF CALIFORNIA SANTA CRUZ A STOCHASTIC DYNAMIC MODEL OF THE BEHAVIORAL ECOLOGY #12;Play behavior has been shown to occur in a surprisingly diverse range of animals, and yet

  13. Scale-dependent foraging ecology of a marine top predator modelled using passive acoustic data

    E-print Network

    Aberdeen, University of

    Scale-dependent foraging ecology of a marine top predator modelled using passive acoustic data especially challenging in marine predators, but passive acoustic techniques provide opportunities to study the behaviour of echolocating species over a range of scales. 2. We used an extensive passive acoustic data set

  14. A Faculty-Development Model for Transforming Introductory Biology and Ecology Courses

    ERIC Educational Resources Information Center

    D'Avanzo, Charlene; Anderson, Charles W.; Hartley, Laurel M.; Pelaez, Nancy

    2012-01-01

    The Diagnostic Question Cluster (DQC) project integrates education research and faculty development to articulate a model for the effective transformation of introductory biology and ecology teaching. Over three years, faculty members from a wide range of institutions used active teaching and DQCs, a type of concept inventory, as pre- and…

  15. A linked model of animal ecology and human behavior for the management of wildlife tourism

    Microsoft Academic Search

    Christina A. D. Semeniuk; Wolfgang Haider; Andrew Cooper; Kristina D. Rothley

    2010-01-01

    Wildlife tourism attractions are characterized as having intricately coupled human–wildlife interactions. Accordingly, the ability to mitigate negative impacts of tourism on wildlife necessitates research into the ecology of the system and of the human dimensions, since plans aimed at optimizing wildlife fitness must also be acceptable to tourists. We developed an integrated systems dynamics model for the management of tourist–stingray

  16. Exploring the Influence of a Social Ecological Model on School-Based Physical Activity

    ERIC Educational Resources Information Center

    Langille, Jessie-Lee D.; Rodgers, Wendy M.

    2010-01-01

    Among rising rates of overweight and obesity, schools have become essential settings to promote health behaviors, such as physical activity (PA). As schools exist within a broader environment, the social ecological model (SEM) provided a framework to consider how different levels interact and influence PA. The purpose of this study was to provide…

  17. ECOLOGICAL ENDPOINT MODELING FOR TMDLS: EFFECTS OF SEDIMENT ON FISH POPULATIONS

    EPA Science Inventory

    Sediment is one of the primary stressors of concern for Total Maximum Daily Loads (TMDLs) for streams, and often it is a concern because of its impact on ecological endpoints. A modeling approach relating sediment to stream fish population dynamics is presented. Equations are d...

  18. Ecological Modelling 192 (2006) 175187 Eco-environmental vulnerability evaluation in mountainous

    E-print Network

    Liang, Shunlin

    2006-01-01

    Ecological Modelling 192 (2006) 175­187 Eco-environmental vulnerability evaluation in mountainous vulnerability and sensitivity according to National Eco-environmental Renovating Scheme of china. In order to analyze eco-environmental vulnera- bility, remote sensing (RS) and geographical information system (GIS

  19. Southward Pleistocene migration of Douglas-fir into Mexico: phylogeography, ecological niche modeling,

    E-print Network

    Gugger, Paul F.

    Southward Pleistocene migration of Douglas-fir into Mexico: phylogeography, ecological niche modeling, Mexico, mtDNA, phylogeography, Pseudotsuga menziesii, rear edge. Summary · Poleward Pleistocene or Pleistocene origin for temperate `sky island' plant taxa in Mexico. These `rear edge' populations situated

  20. An Ecological Risk Model for Early Childhood Anxiety: The Importance of Early Child Symptoms and Temperament

    ERIC Educational Resources Information Center

    Mian, Nicholas D.; Wainwright, Laurel; Briggs-Gowan, Margaret J.; Carter, Alice S.

    2011-01-01

    Childhood anxiety is impairing and associated with later emotional disorders. Studying risk factors for child anxiety may allow earlier identification of at-risk children for prevention efforts. This study applied an ecological risk model to address how early childhood anxiety symptoms, child temperament, maternal anxiety and depression symptoms,…

  1. Granularity and Disaggregation in Compositional Modelling with Applications to Ecological Systems

    E-print Network

    Keppens, Jeroen

    Granularity and Disaggregation in Compositional Modelling with Applications to Ecological Systems Jeroen Keppensa and Qiang Shenb a Dept. of Computer Science, King's College London, Strand, London WC2R 2LS, UK b Dept. of Computer Science, University of Wales, Aberystwyth SY23 3DB, UK Abstract

  2. The painted turtle, Chrysemys picta: a model system for vertebrate evolution, ecology, and human health.

    PubMed

    Valenzuela, Nicole

    2009-07-01

    Painted turtles (Chrysemys picta) are representatives of a vertebrate clade whose biology and phylogenetic position hold a key to our understanding of fundamental aspects of vertebrate evolution. These features make them an ideal emerging model system. Extensive ecological and physiological research provide the context in which to place new research advances in evolutionary genetics, genomics, evolutionary developmental biology, and ecological developmental biology which are enabled by current resources, such as a bacterial artificial chromosome (BAC) library of C. picta, and the imminent development of additional ones such as genome sequences and cDNA and expressed sequence tag (EST) libraries. This integrative approach will allow the research community to continue making advances to provide functional and evolutionary explanations for the lability of biological traits found not only among reptiles but vertebrates in general. Moreover, because humans and reptiles share a common ancestor, and given the ease of using nonplacental vertebrates in experimental biology compared with mammalian embryos, painted turtles are also an emerging model system for biomedical research. For example, painted turtles have been studied to understand many biological responses to overwintering and anoxia, as potential sentinels for environmental xenobiotics, and as a model to decipher the ecology and evolution of sexual development and reproduction. Thus, painted turtles are an excellent reptilian model system for studies with human health, environmental, ecological, and evolutionary significance. PMID:20147199

  3. Modelling bryophyte distribution based on ecological information for extent of occurrence assessment

    Microsoft Academic Search

    Cecília Sérgio; Rui Figueira; David Draper; Rui Menezes; António Jorge Sousa

    2007-01-01

    For some groups such as bryophytes, the IUCN distribution criteria are of critical importance to evaluate threat status, since other parameters cannot be determined readily. In this study, we propose the use of ecological niche modelling methods to estimate the extent of occurrence (EOO) of species. Herbarium (LISU) collection data are used to estimate the potential distribution of bryophytes based

  4. Ecological Modelling 178 (2004) 349356 Growth dilution in multilevel food chains

    E-print Network

    Vermont, University of

    2004-01-01

    Ecological Modelling 178 (2004) 349­356 Growth dilution in multilevel food chains Robert A of growth dilution in all trophic levels of a food chain. We are concerned with concentration as well by Elsevier B.V. Keywords: Growth dilution; Bioaccumulation; Biomagnification; Food chain 1. Introduction

  5. Local Geostatistical Models and Big Data in Hydrological and Ecological Applications

    NASA Astrophysics Data System (ADS)

    Hristopulos, Dionissios

    2015-04-01

    The advent of the big data era creates new opportunities for environmental and ecological modelling but also presents significant challenges. The availability of remote sensing images and low-cost wireless sensor networks implies that spatiotemporal environmental data to cover larger spatial domains at higher spatial and temporal resolution for longer time windows. Handling such voluminous data presents several technical and scientific challenges. In particular, the geostatistical methods used to process spatiotemporal data need to overcome the dimensionality curse associated with the need to store and invert large covariance matrices. There are various mathematical approaches for addressing the dimensionality problem, including change of basis, dimensionality reduction, hierarchical schemes, and local approximations. We present a Stochastic Local Interaction (SLI) model that can be used to model local correlations in spatial data. SLI is a random field model suitable for data on discrete supports (i.e., regular lattices or irregular sampling grids). The degree of localization is determined by means of kernel functions and appropriate bandwidths. The strength of the correlations is determined by means of coefficients. In the "plain vanilla" version the parameter set involves scale and rigidity coefficients as well as a characteristic length. The latter determines in connection with the rigidity coefficient the correlation length of the random field. The SLI model is based on statistical field theory and extends previous research on Spartan spatial random fields [2,3] from continuum spaces to explicitly discrete supports. The SLI kernel functions employ adaptive bandwidths learned from the sampling spatial distribution [1]. The SLI precision matrix is expressed explicitly in terms of the model parameter and the kernel function. Hence, covariance matrix inversion is not necessary for parameter inference that is based on leave-one-out cross validation. This property helps to overcome a significant computational bottleneck of geostatistical models due to the poor scaling of the matrix inversion [4,5]. We present applications to real and simulated data sets, including the Walker lake data, and we investigate the SLI performance using various statistical cross validation measures. References [1] T. Hofmann, B. Schlkopf, A.J. Smola, Annals of Statistics, 36, 1171-1220 (2008). [2] D. T. Hristopulos, SIAM Journal on Scientific Computing, 24(6): 2125-2162 (2003). [3] D. T. Hristopulos and S. N. Elogne, IEEE Transactions on Signal Processing, 57(9): 3475-3487 (2009) [4] G. Jona Lasinio, G. Mastrantonio, and A. Pollice, Statistical Methods and Applications, 22(1):97-112 (2013) [5] Sun, Y., B. Li, and M. G. Genton (2012). Geostatistics for large datasets. In: Advances and Challenges in Space-time Modelling of Natural Events, Lecture Notes in Statistics, pp. 55-77. Springer, Berlin-Heidelberg.

  6. Integrating Evolution into Ecological Modelling: Accommodating Phenotypic Changes in Agent Based Models

    PubMed Central

    Moustakas, Aristides; Evans, Matthew R.

    2013-01-01

    Evolutionary change is a characteristic of living organisms and forms one of the ways in which species adapt to changed conditions. However, most ecological models do not incorporate this ubiquitous phenomenon. We have developed a model that takes a ‘phenotypic gambit’ approach and focuses on changes in the frequency of phenotypes (which differ in timing of breeding and fecundity) within a population, using, as an example, seasonal breeding. Fitness per phenotype calculated as the individual’s contribution to population growth on an annual basis coincide with the population dynamics per phenotype. Simplified model variants were explored to examine whether the complexity included in the model is justified. Outputs from the spatially implicit model underestimated the number of individuals across all phenotypes. When no phenotype transitions are included (i.e. offspring always inherit their parent’s phenotype) numbers of all individuals are always underestimated. We conclude that by using a phenotypic gambit approach evolutionary dynamics can be incorporated into individual based models, and that all that is required is an understanding of the probability of offspring inheriting the parental phenotype. PMID:23940700

  7. Journal of Animal Ecology 2002

    E-print Network

    Walters, Jeffrey R.

    The consequences of disrupted dispersal in fragmented red-cockaded woodpecker Picoides borealis populations KARIN Picoides borealis. 3. We simulated population dynamics as a function of population size and spatial- based model, Picoides borealis, spatially explicit. Journal of Animal Ecology (2002) 71, 710

  8. Adaptive System Modeling for Spacecraft Simulation

    NASA Technical Reports Server (NTRS)

    Thomas, Justin

    2011-01-01

    This invention introduces a methodology and associated software tools for automatically learning spacecraft system models without any assumptions regarding system behavior. Data stream mining techniques were used to learn models for critical portions of the International Space Station (ISS) Electrical Power System (EPS). Evaluation on historical ISS telemetry data shows that adaptive system modeling reduces simulation error anywhere from 50 to 90 percent over existing approaches. The purpose of the methodology is to outline how someone can create accurate system models from sensor (telemetry) data. The purpose of the software is to support the methodology. The software provides analysis tools to design the adaptive models. The software also provides the algorithms to initially build system models and continuously update them from the latest streaming sensor data. The main strengths are as follows: Creates accurate spacecraft system models without in-depth system knowledge or any assumptions about system behavior. Automatically updates/calibrates system models using the latest streaming sensor data. Creates device specific models that capture the exact behavior of devices of the same type. Adapts to evolving systems. Can reduce computational complexity (faster simulations).

  9. Ecological responses to simulated agricultural runoff in a riverine backwater wetland

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Riverine backwater wetlands within river floodplains provide valuable ecological functions such as acting as filters for suspended sediment, nutrients and pesticides entering from adjacent agricultural fields, as well as habitat and refugia for aquatic biota. A 500 m long, 20 m wide riverine backwa...

  10. From patterns to causal understanding: Structural equation modeling (SEM) in soil ecology

    USGS Publications Warehouse

    Eisenhauer, Nico; Powell, Jeff R; Grace, James B.; Bowker, Matthew A.

    2015-01-01

    In this perspectives paper we highlight a heretofore underused statistical method in soil ecological research, structural equation modeling (SEM). SEM is commonly used in the general ecological literature to develop causal understanding from observational data, but has been more slowly adopted by soil ecologists. We provide some basic information on the many advantages and possibilities associated with using SEM and provide some examples of how SEM can be used by soil ecologists to shift focus from describing patterns to developing causal understanding and inspiring new types of experimental tests. SEM is a promising tool to aid the growth of soil ecology as a discipline, particularly by supporting research that is increasingly hypothesis-driven and interdisciplinary, thus shining light into the black box of interactions belowground.

  11. ADAPTABLE SIMULATION MODELS FOR MANUFACTURING Jeffrey W. Herrmann1

    E-print Network

    Herrmann, Jeffrey W.

    ADAPTABLE SIMULATION MODELS FOR MANUFACTURING Jeffrey W. Herrmann1 , Edward Lin1 , Bala Ram2 of Industrial Engineering, North Carolina A&T State University ABSTRACT: Discrete-event simulation is a powerful the simulation model, running the model, and analyzing the output are the basic steps in a simulation study

  12. Global Particle Simulation as A Space Weather Model

    E-print Network

    Nishikawa, Ken-Ichi

    Global Particle Simulation as A Space Weather Model Ken Nishikawa Rutgers University http at the present time, but it will become a vital model · MHD simulations with localized particle simulations very's: Long geomagnetic tail, refined ionosphere models. · 1992: First global particle simulation

  13. Advances in NLTE Modeling for Integrated Simulations

    SciTech Connect

    Scott, H A; Hansen, S B

    2009-07-08

    The last few years have seen significant progress in constructing the atomic models required for non-local thermodynamic equilibrium (NLTE) simulations. Along with this has come an increased understanding of the requirements for accurately modeling the ionization balance, energy content and radiative properties of different elements for a wide range of densities and temperatures. Much of this progress is the result of a series of workshops dedicated to comparing the results from different codes and computational approaches applied to a series of test problems. The results of these workshops emphasized the importance of atomic model completeness, especially in doubly excited states and autoionization transitions, to calculating ionization balance, and the importance of accurate, detailed atomic data to producing reliable spectra. We describe a simple screened-hydrogenic model that calculates NLTE ionization balance with surprising accuracy, at a low enough computational cost for routine use in radiation-hydrodynamics codes. The model incorporates term splitting, {Delta}n = 0 transitions, and approximate UTA widths for spectral calculations, with results comparable to those of much more detailed codes. Simulations done with this model have been increasingly successful at matching experimental data for laser-driven systems and hohlraums. Accurate and efficient atomic models are just one requirement for integrated NLTE simulations. Coupling the atomic kinetics to hydrodynamics and radiation transport constrains both discretizations and algorithms to retain energy conservation, accuracy and stability. In particular, the strong coupling between radiation and populations can require either very short timesteps or significantly modified radiation transport algorithms to account for NLTE material response. Considerations such as these continue to provide challenges for NLTE simulations.

  14. Macro Level Simulation Model Of Space Shuttle Processing

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The contents include: 1) Space Shuttle Processing Simulation Model; 2) Knowledge Acquisition; 3) Simulation Input Analysis; 4) Model Applications in Current Shuttle Environment; and 5) Model Applications for Future Reusable Launch Vehicles (RLV's). This paper is presented in viewgraph form.

  15. Advanced Modeling, Simulation and Analysis (AMSA) Capability Roadmap Progress Review

    NASA Technical Reports Server (NTRS)

    Antonsson, Erik; Gombosi, Tamas

    2005-01-01

    Contents include the following: NASA capability roadmap activity. Advanced modeling, simulation, and analysis overview. Scientific modeling and simulation. Operations modeling. Multi-special sensing (UV-gamma). System integration. M and S Environments and Infrastructure.

  16. [Analysis on sustainable development of marine economy in Jiangsu Province based on marine ecological footprint correction model].

    PubMed

    Yang, Shan; Wang, Yu-ting

    2011-03-01

    Based on the theories and methods of ecological footprint, the concept of marine ecological footprint was proposed. According to the characteristics of marine environment in Jiangsu Province, five sub-models of marine ecological footprints, including fishery, transporation, marine engineering construction, marine energy, and tidal flat, were constructed. The equilibrium factors of the five marine types were determined by using improved entropy method, and the marine footprints and capacities in Jiangsu Province from 2000 to 2008 were calculated and analyzed. In 2000-2008, the marine ecology footprint per capita in Jiangsu Province increased nearly seven times, from 36.90 hm2 to 252.94 hm2, and the ecological capacity per capita grew steadily, from 105.01 hm2 to 185.49 hm2. In 2000, the marine environment in the Province was in a state of ecological surplus, and the marine economy was in a weak sustainable development state. Since 2004, the marine ecological environment deteriorated sharply, with ecological deficit up to 109660.5 hm2, and the sustainability of marine economy declined. The high ecological footprint of fishery was the main reason for the ecological deficit. Tidal flat was the important reserve resource for the sustainable development of marine economy in Jiangsu Province. PMID:21657034

  17. A Simulation Model of IS Security.

    SciTech Connect

    Pendegraft, Norman; Rounds, Mark; Frincke, Deborah A.

    2005-07-01

    Determination of the actual value of security measures is an area currently undergoing scrutiny by many researchers. One method to determine this is to devise a simulation model that incorporates interactions between an information system, its users and a population of attackers. Initial simulation results suggest that the marginal value of additional security may be positive or negative as can the time rate of change of system value. Policy implications include the realization that IT security policy makers should be aware of their location in the state space before setting IT security policy.

  18. Fault diagnosis based on continuous simulation models

    NASA Technical Reports Server (NTRS)

    Feyock, Stefan

    1987-01-01

    The results are described of an investigation of techniques for using continuous simulation models as basis for reasoning about physical systems, with emphasis on the diagnosis of system faults. It is assumed that a continuous simulation model of the properly operating system is available. Malfunctions are diagnosed by posing the question: how can we make the model behave like that. The adjustments that must be made to the model to produce the observed behavior usually provide definitive clues to the nature of the malfunction. A novel application of Dijkstra's weakest precondition predicate transformer is used to derive the preconditions for producing the required model behavior. To minimize the size of the search space, an envisionment generator based on interval mathematics was developed. In addition to its intended application, the ability to generate qualitative state spaces automatically from quantitative simulations proved to be a fruitful avenue of investigation in its own right. Implementations of the Dijkstra transform and the envisionment generator are reproduced in the Appendix.

  19. Robust three-body water simulation model.

    PubMed

    Tainter, C J; Pieniazek, P A; Lin, Y-S; Skinner, J L

    2011-05-14

    The most common potentials used in classical simulations of liquid water assume a pairwise additive form. Although these models have been very successful in reproducing many properties of liquid water at ambient conditions, none is able to describe accurately water throughout its complicated phase diagram. The primary reason for this is the neglect of many-body interactions. To this end, a simulation model with explicit three-body interactions was introduced recently [R. Kumar and J. L. Skinner, J. Phys. Chem. B 112, 8311 (2008)]. This model was parameterized to fit the experimental O-O radial distribution function and diffusion constant. Herein we reparameterize the model, fitting to a wider range of experimental properties (diffusion constant, rotational correlation time, density for the liquid, liquid/vapor surface tension, melting point, and the ice Ih density). The robustness of the model is then verified by comparing simulation to experiment for a number of other quantities (enthalpy of vaporization, dielectric constant, Debye relaxation time, temperature of maximum density, and the temperature-dependent second and third virial coefficients), with good agreement. PMID:21568515

  20. Electron precipitation models in global magnetosphere simulations

    NASA Astrophysics Data System (ADS)

    Zhang, B.; Lotko, W.; Brambles, O.; Wiltberger, M.; Lyon, J.

    2015-02-01

    General methods for improving the specification of electron precipitation in global simulations are described and implemented in the Lyon-Fedder-Mobarry (LFM) global simulation model, and the quality of its predictions for precipitation is assessed. LFM's existing diffuse and monoenergetic electron precipitation models are improved, and new models are developed for lower energy, broadband, and direct-entry cusp precipitation. The LFM simulation results for combined diffuse plus monoenergetic electron precipitation exhibit a quadratic increase in the hemispheric precipitation power as the intensity of solar wind driving increases, in contrast with the prediction from the OVATION Prime (OP) 2010 empirical precipitation model which increases linearly with driving intensity. Broadband precipitation power increases approximately linearly with driving intensity in both models. Comparisons of LFM and OP predictions with estimates of precipitating power derived from inversions of Polar satellite UVI images during a double substorm event (28-29 March 1998) show that the LFM peak precipitating power is >4× larger when using the improved precipitation model and most closely tracks the larger of three different inversion estimates. The OP prediction most closely tracks the double peaks in the intermediate inversion estimate, but it overestimates the precipitating power between the two substorms by a factor >2 relative to all other estimates. LFMs polar pattern of precipitating energy flux tracks that of OP for broadband precipitation exhibits good correlation with duskside region 1 currents for monoenergetic energy flux that OP misses and fails to produce sufficient diffuse precipitation power in the prenoon quadrant that is present in OP. The prenoon deficiency is most likely due to the absence of drift kinetic physics in the LFM simulation.

  1. ADVANCED UTILITY SIMULATION MODEL, MODEL OPERATIONS (VERSION 1.0)

    EPA Science Inventory

    The report is one of several in a series describing the initial development--by the Universities Research Group on Energy (URGE)--of the Advanced Utility Simulation Model (AUSM), one of four stationary source emission and control cost forecasting models developed by the U.S. EPA ...

  2. A generalized reactive separation unit model. Modelling and simulation aspects

    Microsoft Academic Search

    Rafiqul Gani; Thomas S. Jepsen; Eduardo S. Pérez-Cisneros

    1998-01-01

    The modelling and simulation of a generalized reactive separation unit has been developed. The generalized reactive separation unit is able to consider multiple configurations where the reaction and separation may occur simultaneously or where only a single separation process (multiphase) or single reaction process (multireaction) may take place. Therefore, through the generalized reactive separation unit model, it is possible to

  3. Applications of Ecological Niche Modeling for Species Delimitation: A Review and Empirical Evaluation Using Day Geckos (Phelsuma) from Madagascar

    Microsoft Academic Search

    CHRISTOPHER J. RAXWORTHY; COLLEEN M. INGRAM; Nirhy Rabibisoa; RICHARD G. PEARSON

    2007-01-01

    Although the systematic utility of ecological niche modeling is generally well known (e.g., concerning the recog- nition and discovery of areas of endemism for biogeographic analyses), there has been little discussion of applications concerning species delimitation, and to date, no empirical evaluation has been conducted. However, ecological niche mod- eling can provide compelling evidence for allopatry between populations, and can

  4. Modelling and Simulation1 version 1.1

    E-print Network

    Parallel Scientific Computing and Simulations under `Publications.' 2 Dr. P.M.A. Sloot is an associate professor in parallel scientific computing and simulation at the University of Amsterdam and can be reached at system models...........................................................6 Intermezzo: Simulation Lingo

  5. LISP based simulation generators for modeling complex space processes

    NASA Technical Reports Server (NTRS)

    Tseng, Fan T.; Schroer, Bernard J.; Dwan, Wen-Shing

    1987-01-01

    The development of a simulation assistant for modeling discrete event processes is presented. Included are an overview of the system, a description of the simulation generators, and a sample process generated using the simulation assistant.

  6. [Construction of individual-based ecological model for Scomber japonicas at its early growth stages in East China Sea].

    PubMed

    Li, Yue-Song; Chen, Xin-Jun; Yang, Hong

    2012-06-01

    By adopting FVCOM-simulated 3-D physical field and based on the biological processes of chub mackerel (Scomber japonicas) in its early life history from the individual-based biological model, the individual-based ecological model for S. japonicas at its early growth stages in the East China Sea was constructed through coupling the physical field in March-July with the biological model by the method of Lagrange particle tracking. The model constructed could well simulate the transport process and abundance distribution of S. japonicas eggs and larvae. The Taiwan Warm Current, Kuroshio, and Tsushima Strait Warm Current directly affected the transport process and distribution of the eggs and larvae, and indirectly affected the growth and survive of the eggs and larvae through the transport to the nursery grounds with different water temperature and foods. The spawning grounds in southern East China Sea made more contributions to the recruitment to the fishing grounds in northeast East China Sea, but less to the Yangtze estuary and Zhoushan Island. The northwestern and southwestern parts of spawning grounds had strong connectivity with the nursery grounds of Cheju and Tsushima Straits, whereas the northeastern and southeastern parts of the spawning ground had strong connectivity with the nursery grounds of Kyushu and Pacific Ocean. PMID:22937663

  7. A simulation model for material accounting systems

    SciTech Connect

    Coulter, C.A.; Thomas, K.E.

    1987-01-01

    A general-purpose model that was developed to simulate the operation of a chemical processing facility for nuclear materials has been extended to describe material measurement and accounting procedures as well. The model now provides descriptors for material balance areas, a large class of measurement instrument types and their associated measurement errors for various classes of materials, the measurement instruments themselves with their individual calibration schedules, and material balance closures. Delayed receipt of measurement results (as for off-line analytical chemistry assay), with interim use of a provisional measurement value, can be accurately represented. The simulation model can be used to estimate inventory difference variances for processing areas that do not operate at steady state, to evaluate the timeliness of measurement information, to determine process impacts of measurement requirements, and to evaluate the effectiveness of diversion-detection algorithms. Such information is usually difficult to obtain by other means. Use of the measurement simulation model is illustrated by applying it to estimate inventory difference variances for two material balance area structures of a fictitious nuclear material processing line.

  8. A superbubble feedback model for galaxy simulations

    NASA Astrophysics Data System (ADS)

    Keller, B. W.; Wadsley, J.; Benincasa, S. M.; Couchman, H. M. P.

    2014-08-01

    We present a new stellar feedback model that reproduces superbubbles. Superbubbles from clustered young stars evolve quite differently to individual supernovae and are substantially more efficient at generating gas motions. The essential new components of the model are thermal conduction, subgrid evaporation and a subgrid multiphase treatment for cases where the simulation mass resolution is insufficient to model the early stages of the superbubble. The multiphase stage is short compared to superbubble lifetimes. Thermal conduction physically regulates the hot gas mass without requiring a free parameter. Accurately following the hot component naturally avoids overcooling. Prior approaches tend to heat too much mass, leaving the hot interstellar medium (ISM) below 106 K and susceptible to rapid cooling unless ad hoc fixes were used. The hot phase also allows feedback energy to correctly accumulate from multiple, clustered sources, including stellar winds and supernovae. We employ high-resolution simulations of a single star cluster to show the model is insensitive to numerical resolution, unresolved ISM structure and suppression of conduction by magnetic fields. We also simulate a Milky Way analogue and a dwarf galaxy. Both galaxies show regulated star formation and produce strong outflows.

  9. Uncertainty analysis of a spatial habitat suitability model and implications for ecological management of water bodies

    Microsoft Academic Search

    Guda E. M. Van der Lee; Diederik T. Van der Molen; Henk F. P. Van den Boogaard; Hanneke Van der Klis

    2006-01-01

    Habitat suitability index (HSI) models have been generally accepted in ecological management as a means to predict effects\\u000a of pressures and restoration measures on habitats and populations. HSI-models estimate habitat suitability from relevant habitat\\u000a variables. Because outcomes of HSI-studies may have significant consequences, it is crucial to have insight into the uncertainties\\u000a of the predictions. In this study a method

  10. Theory, modeling and simulation: Annual report 1993

    SciTech Connect

    Dunning, T.H. Jr.; Garrett, B.C.

    1994-07-01

    Developing the knowledge base needed to address the environmental restoration issues of the US Department of Energy requires a fundamental understanding of molecules and their interactions in insolation and in liquids, on surfaces, and at interfaces. To meet these needs, the PNL has established the Environmental and Molecular Sciences Laboratory (EMSL) and will soon begin construction of a new, collaborative research facility devoted to advancing the understanding of environmental molecular science. Research in the Theory, Modeling, and Simulation program (TMS), which is one of seven research directorates in the EMSL, will play a critical role in understanding molecular processes important in restoring DOE`s research, development and production sites, including understanding the migration and reactions of contaminants in soils and groundwater, the development of separation process for isolation of pollutants, the development of improved materials for waste storage, understanding the enzymatic reactions involved in the biodegradation of contaminants, and understanding the interaction of hazardous chemicals with living organisms. The research objectives of the TMS program are to apply available techniques to study fundamental molecular processes involved in natural and contaminated systems; to extend current techniques to treat molecular systems of future importance and to develop techniques for addressing problems that are computationally intractable at present; to apply molecular modeling techniques to simulate molecular processes occurring in the multispecies, multiphase systems characteristic of natural and polluted environments; and to extend current molecular modeling techniques to treat complex molecular systems and to improve the reliability and accuracy of such simulations. The program contains three research activities: Molecular Theory/Modeling, Solid State Theory, and Biomolecular Modeling/Simulation. Extended abstracts are presented for 89 studies.

  11. Gecko: A Continuous 2D World for Ecological Modeling

    Microsoft Academic Search

    Ginger Booth

    1997-01-01

    An individual-based simulation system is presented for modelingmultiple species at multiple trophic levels, on a spatially explicit, continuoustwo-dimensional landscape. Biologically motivated rules arespecified at an individual level, and resulting behaviors are observedat an ecosystem level. Individuals are represented by circles with freerange on a resource-producing plane. These circles grow allometricallywith biomass of fixed resources. Resource acquisition behaviorsinclude...

  12. forest ecology Future Fire Probability Modeling with Climate

    E-print Network

    Stambaugh, Michael C

    a primary influence on the occurrence and rate of combustion in ecosystems with carbon-based fuels climate simulations of temperature and precipitation. The probability of a fire occurring in a particular and probabilities from the difference between current and future climates and mapped climate-forced percentage

  13. Model Validation of Power System Components Using Hybrid Dynamic Simulation

    SciTech Connect

    Huang, Zhenyu; Nguyen, Tony B.; Kosterev, Dmitry; Guttromson, Ross T.

    2008-05-31

    Hybrid dynamic simulation, with its capability of injecting external signals into dynamic simulation, opens the traditional dynamic simulation loop for interaction with actual field measurements. This simulation technique enables rigorous comparison between simulation results and actual measurements and model validation of individual power system components within a small subsystem. This paper uses a real example of generator model validation to illustrate the procedure and validity of the component model validation methodology using hybrid dynamic simulation. Initial model calibration has also been carried out to show how model validation results would be used to improve component models

  14. Model Validation of Power System Components Using Hybrid Dynamic Simulation

    SciTech Connect

    Huang, Zhenyu; Nguyen, Tony B.; Kosterev, Dmitry; Guttromson, Ross T.

    2006-05-21

    Abstract—Hybrid dynamic simulation, with its capability of injecting external signals into dynamic simulation, opens the traditional dynamic simulation loop for interaction with actual field measurements. This simulation technique enables rigorous comparison between simulation results and actual measurements and model validation of individual power system components within a small subsystem. This paper uses a real example of generator model validation to illustrate the procedure and validity of the component model validation methodology using hybrid dynamic simulation. Initial model calibration has also been carried out to show how model validation results would be used to improve component models.

  15. Effects of stream topology on ecological community results from neutral models

    EPA Science Inventory

    While neutral theory and models have stimulated considerable literature, less well investigated is the effect of topology on neutral metacommunity model simulations. We implemented a neutral metacommunity model using two different stream network topologies, a widely branched netw...

  16. Cognitive Modeling for Agent-based Simulation of Child Maltreatment

    E-print Network

    Hu, Xiaolin

    Cognitive Modeling for Agent-based Simulation of Child Maltreatment Xiaolin Hu1 , Richard Puddy2 1-based simulation of child maltreatment (CM). The developed model is inspired from parental efficacy, parenting the features of this model. Keywords: Child maltreatment, cognitive modeling, agent-based simulation, parental

  17. Comparison of numerical simulations of reactive transport and chemostat-like models

    E-print Network

    Haidar, Ihab; Rapaport, Alain

    2011-01-01

    The objective of the paper is to evaluate the ability of reactive transport models and their numerical implementations (such as MIN3P) to simulate simple microbial transformations in conditions of chemostat or gradostat models, that are popular in microbial ecology and waste treatment ecosystems. To make this comparison, we first consider an abstract ecosystem composed of a single limiting resource and a single microbial species that are carried by advection. In a second stage, we consider another microbial species in competition for the same limiting resource. Comparing the numerical solutions of the two models, we found that the numerical accuracy of simulations of advective transport models performed with MIN3P depends on the evolution of the concentrations of the microbial species: when the state of the system is close to a non-hyperbolic equilibrium, we observe a numerical inaccuracy that may be due to the discretization method used in numerical approximations of reactive transport equations. Therefore, ...

  18. Implications of Simulation Conceptual Model Development for Simulation Management and Uncertainty Assessment

    NASA Technical Reports Server (NTRS)

    Pace, Dale K.

    2000-01-01

    A simulation conceptual model is a simulation developers way of translating modeling requirements (i. e., what is to be represented by the simulation or its modification) into a detailed design framework (i. e., how it is to be done), from which the software, hardware, networks (in the case of distributed simulation), and systems/equipment that will make up the simulation can be built or modified. A conceptual model is the collection of information which describes a simulation developers concept about the simulation and its pieces. That information consists of assumptions, algorithms, characteristics, relationships, and data. Taken together, these describe how the simulation developer understands what is to be represented by the simulation (entities, actions, tasks, processes, interactions, etc.) and how that representation will satisfy the requirements to which the simulation responds. Thus the conceptual model is the basis for judgment about simulation fidelity and validity for any condition that is not specifically tested. The more perspicuous and precise the conceptual model, the more likely it is that the simulation development will both fully satisfy requirements and allow demonstration that the requirements are satisfied (i. e., validation). Methods used in simulation conceptual model development have significant implications for simulation management and for assessment of simulation uncertainty. This paper suggests how to develop and document a simulation conceptual model so that the simulation fidelity and validity can be most effectively determined. These ideas for conceptual model development apply to all simulation varieties. The paper relates these ideas to uncertainty assessments as they relate to simulation fidelity and validity. The paper also explores implications for simulation management from conceptual model development methods, especially relative to reuse of simulation components.

  19. Simulation Model of Mobile Detection Systems

    Microsoft Academic Search

    T Edmunds; D Faissol; Y Yao

    2009-01-01

    In this paper, we consider a mobile source that we attempt to detect with man-portable, vehicle-mounted or boat-mounted radiation detectors. The source is assumed to transit an area populated with these mobile detectors, and the objective is to detect the source before it reaches a perimeter. We describe a simulation model developed to estimate the probability that one of the

  20. Hybrid cutting simulation via discrete vector model

    Microsoft Academic Search

    Jung W. Park; Yang H. Shin; Yun C. Chung

    2005-01-01

    Geometric cutting simulation and verification play an important role in detecting NC machining errors in mold and die manufacturing, thereby reducing the correcting time and cost on the shop floor. According to workpiece model, current researches may be categorized into view-based, solid-based, and discrete vector-based methods. Each methodology has its own strengths and weaknesses in terms of computing speed, representation

  1. Teaching with Data, Simulations and Models

    NSDL National Science Digital Library

    Today's geoscience education reaches beyond the traditional teaching tools such as rock samples and topographic maps. With the addition of computers in many geoscience classrooms and laboratories, faculty have unprecedented opportunity to create innovative learning experiences by bringing real-world data sets and models and simulations of geoscience processes into the classroom. This site provides resources to help faculty use these resources effectively and easily, by providing access to teaching materials, tips from the classroom and literature about the supporting pedagogy.

  2. Irrigation planning in cotton through simulation modeling

    Microsoft Academic Search

    R. Singh; Joginder Singh

    1996-01-01

    Experiments were undertaken at CCS Haryana Agricultural University Farm, Sirsa (India) to estimate the optimum irrigation\\u000a schedule for cotton resulting in minimum percolation losses. The sprinkler line source technique was adopted for creating\\u000a various irrigation regimes at different crop growth stages. The SWASALT (Simulation of Water And SALT) model after calibration\\u000a and validation provided water balance components. The wa-ter management

  3. A 2-D process-based model for suspended sediment dynamics: a first step towards ecological modeling

    NASA Astrophysics Data System (ADS)

    Achete, F. M.; van der Wegen, M.; Roelvink, D.; Jaffe, B.

    2015-02-01

    In estuaries most of the sediment load is carried in suspension. Sediment dynamics differ depending on sediment supply and hydrodynamic forcing conditions that vary over space and over time. Suspended sediment concentration (SSC) is one of the most important contributors to turbidity, which influences habitat conditions and ecological functions of the system. A robust sediment model is the first step towards a chain of model including contaminants and phytoplankton dynamics and habitat modeling. This works aims to determine turbidity levels in the complex-geometry Delta of San Francisco Estuary using a process-based approach (D-Flow Flexible Mesh software). Our approach includes a detailed calibration against measured SSC levels, a sensitivity analysis on model parameters, the determination of a yearly sediment budget as well as an assessment of model results in terms of turbidity levels for a single year (Water Year 2011). Model results shows that our process-based approach is a valuable tool in assessing sediment dynamics and their related ecological parameters over a range of spatial and temporal scales. The current model may act as the base model for a chain of ecological models and climate scenario forecasting.

  4. Use of Ecological Risk Data in the Development of Visions, Conceptual Site Models and Maps for Department of Energy Lands: Ensuring Sustainability of Protecting Human and Ecological Health

    Microsoft Academic Search

    Joanna Burger

    2005-01-01

    Recent interest in understanding the human and ecological health risks of contaminants on lands in the United States has led some managers and public policy makers to use extensive narratives associated with maps and Conceptual Site Models (CSM) in their Vision statements. While narratives are descriptive, CSMs can graphically depict the sources, releases, transport and exposure pathways, and receptors, together

  5. Computer Modeling and Simulation of Communications Satellite Channels

    Microsoft Academic Search

    LARRY C. PALMER

    1984-01-01

    Computer modeling of satellite communications channels is a valuable adjunct to analytical modeling and hardware simulation for predicting and verifying communications link performance. In the computer simulation approach, sampled signals are created in the computer and operated on by algorithms that simulate the effects of filtering, channel nonlinearities, interference, and noise. After passage through the simulated channel, the distorted signals

  6. Developing effective policies for the sustainable development of ecological agriculture in China: the case study of Jinshan County with a systems dynamics modelB

    Microsoft Academic Search

    Tian Shia; Roderic Gill

    This paper focuses on a search for concrete policy measures to facilitate the overall sustainability of ecological agricultural development at a county level. For this purpose, a system dynamics model (AISEEM) has been developed to explore the potential long-term ecological, economic, institutional and social interactions of ecological agricultural development through a case study of Jinshan County in China. The model

  7. The impacts of multiple stressors to model ecological structures

    SciTech Connect

    Landis, W.G.; Kelly, S.A.; Markiewicz, A.J.; Matthews, R.A. [Huxley Coll. of Environmental Studies, Bellingham, WA (United States); Matthews, G.B. [Western Washington Univ., Bellingham, WA (United States). Computer Science Dept.

    1995-12-31

    The basis of the community conditioning hypothesis is that ecological structures are the result of their unique etiology. Systems that have been exposed to a variety of stressors should reflect this history. The authors how conducted a series of microcosm experiments that can compare the effects of multiple stressors upon community dynamics. The microcosm protocols are derived from the Standardized Aquatic Microcosm (SAM) and have Lemma and additional protozoan species. Two multiple stressor experiments have been conducted. In an extended length SAM (ELSAM), two of four treatments were dosed with the turbine fuel JP-8 one week into the experiment. Two treatments were later exposed to the heat stress, one that had received jet fuel and one that had not. Similarly, an ELSAM was conducted with the second stressor being the further addition of JP-8 replacing the heat shock. Biological, physical and chemical data were analyzed with multivariate techniques including nonmetric clustering and association analysis. Space-time worms and phase diagrams were also employed to ascertain the dynamic relationships of variables identified as important by the multivariate techniques. The experiments do not result in a simple additive linear response to the additional stressor. Examination of the relative population dynamics reveal alterations in trajectories that suggest treatment related effects. As in previous single stressor experiments, recovery does not occur even after extended experimental periods. The authors are now attempting to measure the resulting trajectories, changes in similarity vectors and overall dynamics. However, community conditioning does appear to be an important framework in understanding systems with a heterogeneous array of stressors.

  8. An online database for informing ecological network models: http://kelpforest.ucsc.edu.

    PubMed

    Beas-Luna, Rodrigo; Novak, Mark; Carr, Mark H; Tinker, Martin T; Black, August; Caselle, Jennifer E; Hoban, Michael; Malone, Dan; Iles, Alison

    2014-01-01

    Ecological network models and analyses are recognized as valuable tools for understanding the dynamics and resiliency of ecosystems, and for informing ecosystem-based approaches to management. However, few databases exist that can provide the life history, demographic and species interaction information necessary to parameterize ecological network models. Faced with the difficulty of synthesizing the information required to construct models for kelp forest ecosystems along the West Coast of North America, we developed an online database (http://kelpforest.ucsc.edu/) to facilitate the collation and dissemination of such information. Many of the database's attributes are novel yet the structure is applicable and adaptable to other ecosystem modeling efforts. Information for each taxonomic unit includes stage-specific life history, demography, and body-size allometries. Species interactions include trophic, competitive, facilitative, and parasitic forms. Each data entry is temporally and spatially explicit. The online data entry interface allows researchers anywhere to contribute and access information. Quality control is facilitated by attributing each entry to unique contributor identities and source citations. The database has proven useful as an archive of species and ecosystem-specific information in the development of several ecological network models, for informing management actions, and for education purposes (e.g., undergraduate and graduate training). To facilitate adaptation of the database by other researches for other ecosystems, the code and technical details on how to customize this database and apply it to other ecosystems are freely available and located at the following link (https://github.com/kelpforest-cameo/databaseui). PMID:25343723

  9. Applying ecological models to communities of genetic elements: the case of neutral theory.

    PubMed

    Linquist, Stefan; Cottenie, Karl; Elliott, Tyler A; Saylor, Brent; Kremer, Stefan C; Gregory, T Ryan

    2015-07-01

    A promising recent development in molecular biology involves viewing the genome as a mini-ecosystem, where genetic elements are compared to organisms and the surrounding cellular and genomic structures are regarded as the local environment. Here, we critically evaluate the prospects of ecological neutral theory (ENT), a popular model in ecology, as it applies at the genomic level. This assessment requires an overview of the controversy surrounding neutral models in community ecology. In particular, we discuss the limitations of using ENT both as an explanation of community dynamics and as a null hypothesis. We then analyse a case study in which ENT has been applied to genomic data. Our central finding is that genetic elements do not conform to the requirements of ENT once its assumptions and limitations are made explicit. We further compare this genome-level application of ENT to two other, more familiar approaches in genomics that rely on neutral mechanisms: Kimura's molecular neutral theory and Lynch's mutational-hazard model. Interestingly, this comparison reveals that there are two distinct concepts of neutrality associated with these models, which we dub 'fitness neutrality' and 'competitive neutrality'. This distinction helps to clarify the various roles for neutral models in genomics, for example in explaining the evolution of genome size. PMID:25919906

  10. Computer Models Simulate Fine Particle Dispersion

    NASA Technical Reports Server (NTRS)

    2010-01-01

    Through a NASA Seed Fund partnership with DEM Solutions Inc., of Lebanon, New Hampshire, scientists at Kennedy Space Center refined existing software to study the electrostatic phenomena of granular and bulk materials as they apply to planetary surfaces. The software, EDEM, allows users to import particles and obtain accurate representations of their shapes for modeling purposes, such as simulating bulk solids behavior, and was enhanced to be able to more accurately model fine, abrasive, cohesive particles. These new EDEM capabilities can be applied in many industries unrelated to space exploration and have been adopted by several prominent U.S. companies, including John Deere, Pfizer, and Procter & Gamble.

  11. Integration of environmental simulation models with satellite remote sensing and geographic information systems technologies: case studies

    USGS Publications Warehouse

    Steyaert, Louis T.; Loveland, Thomas R.; Brown, Jesslyn F.; Reed, Bradley C.

    1993-01-01

    Environmental modelers are testing and evaluating a prototype land cover characteristics database for the conterminous United States developed by the EROS Data Center of the U.S. Geological Survey and the University of Nebraska Center for Advanced Land Management Information Technologies. This database was developed from multi temporal, 1-kilometer advanced very high resolution radiometer (AVHRR) data for 1990 and various ancillary data sets such as elevation, ecological regions, and selected climatic normals. Several case studies using this database were analyzed to illustrate the integration of satellite remote sensing and geographic information systems technologies with land-atmosphere interactions models at a variety of spatial and temporal scales. The case studies are representative of contemporary environmental simulation modeling at local to regional levels in global change research, land and water resource management, and environmental simulation modeling at local to regional levels in global change research, land and water resource management and environmental risk assessment. The case studies feature land surface parameterizations for atmospheric mesoscale and global climate models; biogenic-hydrocarbons emissions models; distributed parameter watershed and other hydrological models; and various ecological models such as ecosystem, dynamics, biogeochemical cycles, ecotone variability, and equilibrium vegetation models. The case studies demonstrate the important of multi temporal AVHRR data to develop to develop and maintain a flexible, near-realtime land cover characteristics database. Moreover, such a flexible database is needed to derive various vegetation classification schemes, to aggregate data for nested models, to develop remote sensing algorithms, and to provide data on dynamic landscape characteristics. The case studies illustrate how such a database supports research on spatial heterogeneity, land use, sensitivity analysis, and scaling issues involving regional extrapolations and parameterizations of dynamic land processes within simulation models.

  12. Qualitative simulation for process modeling and control

    NASA Technical Reports Server (NTRS)

    Dalle Molle, D. T.; Edgar, T. F.

    1989-01-01

    A qualitative model is developed for a first-order system with a proportional-integral controller without precise knowledge of the process or controller parameters. Simulation of the qualitative model yields all of the solutions to the system equations. In developing the qualitative model, a necessary condition for the occurrence of oscillatory behavior is identified. Initializations that cannot exhibit oscillatory behavior produce a finite set of behaviors. When the phase-space behavior of the oscillatory behavior is properly constrained, these initializations produce an infinite but comprehensible set of asymptotically stable behaviors. While the predictions include all possible behaviors of the real system, a class of spurious behaviors has been identified. When limited numerical information is included in the model, the number of predictions is significantly reduced.

  13. Common Challenges for Ecological Modelling: Synthesis of Facilitated Discussions Held at the Symposia Organized for the Conference of the International Society for Ecological Modelling in Quebec City, Canada (October 6-9, 2009)

    EPA Science Inventory

    The symposia organized for the conference of the International Society for Ecological Modelling (ISEM 2009) included facilitated discussion sessions following formal presentations. Each symposium focused on a specific subject, and all the subjects could be classified into three b...

  14. A numerical model simulation of longshore transport for Galveston Island 

    E-print Network

    Gilbreath, Stephen Alexander

    1995-01-01

    The shoreline changes, deposition patterns, and longshore transport rates were calculated for the coast of Galveston Island using a numerical model simulation. The model only simulated changes due to waves creating longshore currents. East Beach...

  15. Simulation of models and algorithms for wireless communication systems

    E-print Network

    Jabbour, Imad W

    2007-01-01

    The thesis presents a set of simulations of models and algorithms for wireless communication systems. The simulations are developed using graphical MATLAB interfaces, and cover the fundamentals of wireless channel modeling, ...

  16. Turbulent convection: comparison of Reynolds stress models with numerical simulations

    E-print Network

    Demoulin, Pascal

    Turbulent convection: comparison of Reynolds stress models with numerical simulations Friedrich, University of Vienna, A­1090 Vienna, Austria ABSTRACT Numerical simulations of turbulent convection have of basic properties of compressible convection, and stellar atmospheres. Fully nonlocal convection models

  17. Modelling stream flow for use in ecological studies in a large, arid zone river, central Australia

    NASA Astrophysics Data System (ADS)

    Costelloe, Justin F.; Grayson, Rodger B.; McMahon, Thomas A.

    2005-04-01

    Australian arid zone ephemeral rivers are typically unregulated and maintain a high level of biodiversity and ecological health. Understanding the ecosystem functions of these rivers requires an understanding of their hydrology. These rivers are typified by highly variable hydrological regimes and a paucity, often a complete absence, of hydrological data to describe these flow regimes. A daily time-step, grid-based, conceptual rainfall-runoff model was developed for the previously uninstrumented Neales River in the arid zone of northern South Australia. Hourly, logged stage data provided a record of stream-flow events in the river system. In conjunction with opportunistic gaugings of stream-flow events, these data were used in the calibration of the model. The poorly constrained spatial variability of rainfall distribution and catchment characteristics (e.g. storage depths) limited the accuracy of the model in replicating the absolute magnitudes and volumes of stream-flow events. In particular, small but ecologically important flow events were poorly modelled. Model performance was improved by the application of catchment-wide processes replicating quick runoff from high intensity rainfall and improving the area inundated versus discharge relationship in the channel sections of the model. Representing areas of high and low soil moisture storage depths in the hillslope areas of the catchment also improved the model performance. The need for some explicit representation of the spatial variability of catchment characteristics (e.g. channel/floodplain, low storage hillslope and high storage hillslope) to effectively model the range of stream-flow events makes the development of relatively complex rainfall-runoff models necessary for multisite ecological studies in large, ungauged arid zone catchments. Grid-based conceptual models provide a good balance between providing the capacity to easily define land types with differing rainfall-runoff responses, flexibility in defining data output points and a parsimonious water-balance-routing model.

  18. A heteroskedastic error covariance matrix estimator using a first-order conditional autoregressive Markov simulation for deriving asympotical efficient estimates from ecological sampled Anopheles arabiensis aquatic habitat covariates

    PubMed Central

    Jacob, Benjamin G; Griffith, Daniel A; Muturi, Ephantus J; Caamano, Erick X; Githure, John I; Novak, Robert J

    2009-01-01

    Background Autoregressive regression coefficients for Anopheles arabiensis aquatic habitat models are usually assessed using global error techniques and are reported as error covariance matrices. A global statistic, however, will summarize error estimates from multiple habitat locations. This makes it difficult to identify where there are clusters of An. arabiensis aquatic habitats of acceptable prediction. It is therefore useful to conduct some form of spatial error analysis to detect clusters of An. arabiensis aquatic habitats based on uncertainty residuals from individual sampled habitats. In this research, a method of error estimation for spatial simulation models was demonstrated using autocorrelation indices and eigenfunction spatial filters to distinguish among the effects of parameter uncertainty on a stochastic simulation of ecological sampled Anopheles aquatic habitat covariates. A test for diagnostic checking error residuals in an An. arabiensis aquatic habitat model may enable intervention efforts targeting productive habitats clusters, based on larval/pupal productivity, by using the asymptotic distribution of parameter estimates from a residual autocovariance matrix. The models considered in this research extends a normal regression analysis previously considered in the literature. Methods Field and remote-sampled data were collected during July 2006 to December 2007 in Karima rice-village complex in Mwea, Kenya. SAS 9.1.4® was used to explore univariate statistics, correlations, distributions, and to generate global autocorrelation statistics from the ecological sampled datasets. A local autocorrelation index was also generated using spatial covariance parameters (i.e., Moran's Indices) in a SAS/GIS® database. The Moran's statistic was decomposed into orthogonal and uncorrelated synthetic map pattern components using a Poisson model with a gamma-distributed mean (i.e. negative binomial regression). The eigenfunction values from the spatial configuration matrices were then used to define expectations for prior distributions using a Markov chain Monte Carlo (MCMC) algorithm. A set of posterior means were defined in WinBUGS 1.4.3®. After the model had converged, samples from the conditional distributions were used to summarize the posterior distribution of the parameters. Thereafter, a spatial residual trend analyses was used to evaluate variance uncertainty propagation in the model using an autocovariance error matrix. Results By specifying coefficient estimates in a Bayesian framework, the covariate number of tillers was found to be a significant predictor, positively associated with An. arabiensis aquatic habitats. The spatial filter models accounted for approximately 19% redundant locational information in the ecological sampled An. arabiensis aquatic habitat data. In the residual error estimation model there was significant positive autocorrelation (i.e., clustering of habitats in geographic space) based on log-transformed larval/pupal data and the sampled covariate depth of habitat. Conclusion An autocorrelation error covariance matrix and a spatial filter analyses can prioritize mosquito control strategies by providing a computationally attractive and feasible description of variance uncertainty estimates for correctly identifying clusters of prolific An. arabiensis aquatic habitats based on larval/pupal productivity. PMID:19772590

  19. Modeling Hydrology, Phosphorus and Ecology in the Hampshire Avon Catchment to Assess Alternative Strategies to Improve Water Quality

    NASA Astrophysics Data System (ADS)

    Jin, L.; Whitehead, P. G.; Crossman, J.

    2013-12-01

    Phosphorus (P) enrichment is a worldwide issue of fresh river systems that causes algae blooms, oxygen decline and eutrophication. Therefore, controlling the input of nutrients especially P into aquatic ecosystems is a crucial management focus across much of the world. For example, approximately 70% of water bodies in the Hampshire Avon catchment (UK) are considered not in a good ecological condition due to excess soluble reactive phosphorus (SRP) in the water. In this work, we explored the issues of diffuse and point source P pollution in the Hampshire Avon catchment using an integrated catchment model (INCA) and further we used the model to assess different management options for P reduction. A multi-branch, process based, dynamic water quality model (INCA-P) has been applied to the whole Hampshire Avon river system to simulate water fluxes, concentrations of total phosphorus (TP) and SRP, and ecology. The model has been used to assess impacts of both agricultural runoff and point sources from Waste Water Treatment Plants (WWTPs) on water quality. The results showed that agriculture contributes approximately 40% of the P load and point sources contribute the other 60%. A set of scenarios have been investigated to assess the impacts of alternative P reduction strategies and results suggest that a combined strategy of agricultural P reduction through either fertilizer reductions or better P management together with improved treatment at WWTPs would reduce the SRP concentrations in the river to acceptable levels to meet the European legislation e.g. Water Framework Directive requirements. A seasonal strategy for P reductions from WWTPs would achieve significant benefits at reduced cost.

  20. A Transmission Model for the Ecology of an Avian Blood Parasite in a Temperate Ecosystem

    PubMed Central

    Murdock, Courtney C.; Foufopoulos, Johannes; Simon, Carl P.

    2013-01-01

    Most of our knowledge about avian haemosporidian parasites comes from the Hawaiian archipelago, where recently introduced Plasmodiumrelictum has contributed to the extinction of many endemic avian species. While the ecology of invasive malaria is reasonably understood, the ecology of endemic haemosporidian infection in mainland systems is poorly understood, even though it is the rule rather than the exception. We develop a mathematical model to explore and identify the ecological factors that most influence transmission of the common avian parasite, Leucocytozoonfringillinarum (Apicomplexa). The model was parameterized from White-crowned Sparrow (Zonotrichialeucophrys) and S. silvestre / craigi black fly populations breeding in an alpine ecosystem. We identify and examine the importance of altricial nestlings, the seasonal relapse of infected birds for parasite persistence across breeding seasons, and potential impacts of seasonal changes in black fly emergence on parasite prevalence in a high elevation temperate system. We also use the model to identify and estimate the parameters most influencing transmission dynamics. Our analysis found that relapse of adult birds and young of the year birds were crucial for parasite persistence across multiple seasons. However, distinguishing between nude nestlings and feathered young of the year was unnecessary. Finally, due to model sensitivity to many black fly parameters, parasite prevalence and sparrow recruitment may be most affected by seasonal changes in environmental temperature driving shifts in black fly emergence and gonotrophic cycles. PMID:24073288

  1. Tools from ecology: useful for evaluating infection risk models?

    PubMed

    Brooker, Simon; Hay, Simon I; Bundy, Don A P

    2002-02-01

    Despite the increasing number of models to predict infection risk for a range of diseases, the assessment of their spatial limits, predictive performance and practical application are not widely undertaken. Using the example of Schistosoma haematobium in Africa, this article illustrates how ecozonation and receiver-operator characteristic analysis can help to assess the usefulness of available models objectively. PMID:11832297

  2. Linking dynamic economic and ecological general equilibrium models

    Microsoft Academic Search

    David Finnoff; John Tschirhart

    2008-01-01

    Although ecosystems provide myriad services to economies, only one service is considered in most renewable-resource models. The general equilibrium bioeconomic model introduced here admits a second service, and more importantly it accounts for how the two services are impacted by interactions within an eight-species ecosystem and interactions within a regional economy. Endangered Steller sea lion recovery measures via alternative pollock

  3. Ecological modelling and toxicity data coupled to assess population recovery of marine amphipod Gammarus locusta: Application to disturbance by chronic exposure to aniline.

    PubMed

    de los Santos, Carmen B; Neuparth, Teresa; Torres, Tiago; Martins, Irene; Cunha, Isabel; Sheahan, Dave; McGowan, Tom; Santos, Miguel M

    2015-06-01

    A population agent-based model of marine amphipod Gammarus locusta was designed and implemented as a basis for ecological risk assessment of chemical pollutants impairing life-history traits at the individual level. We further used the model to assess the toxic effects of aniline (a priority hazardous and noxious substance, HNS) on amphipod populations using empirically-built dose-response functions derived from a chronic bioassay that we previously performed with this species. We observed a significant toxicant-induced mortality and adverse effects in reproductive performance (reduction of newborn production) in G. locusta at the individual level. Coupling the population model with the toxicological data from the chronic bioassay allowed the projection of the ecological costs associated with exposure to aniline that might occur in wild populations. Model simulations with different scenarios indicated that even low level prolonged exposure to the HNS aniline can have significant long-term impacts on G. locusta population abundance, until the impacted population returns to undisturbed levels. This approach may be a useful complement in ecotoxicological studies of chemical pollution to transfer individual-collected data to ecological-relevant levels. PMID:25854699

  4. Systematic simulations of modified gravity: chameleon models

    E-print Network

    Philippe Brax; Anne-C. Davis; Baojiu Li; Hans A. Winther; Gong-Bo Zhao

    2013-04-16

    In this work we systematically study the linear and nonlinear structure formation in chameleon theories of modified gravity, using a generic parameterisation which describes a large class of models using only 4 parameters. For this we have modified the N-body simulation code ECOSMOG to perform a total of 65 simulations for different models and parameter values, including the default LCDM. These simulations enable us to explore a significant portion of the parameter space. We have studied the effects of modified gravity on the matter power spectrum and mass function, and found a rich and interesting phenomenology where the difference with the LCDM paradigm cannot be reproduced by a linear analysis even on scales as large as k~0.05h/Mpc, since the latter incorrectly assumes that the modification of gravity depends only on the background matter density. Our results show that the chameleon screening mechanism is significantly more efficient than other mechanisms such as the dilaton and symmetron, especially in high-density regions and at early times, and can serve as a guidance to determine the parts of the chameleon parameter space which are cosmologically interesting and thus merit further studies in the future.

  5. Best Practices for Crash Modeling and Simulation

    NASA Technical Reports Server (NTRS)

    Fasanella, Edwin L.; Jackson, Karen E.

    2002-01-01

    Aviation safety can be greatly enhanced by the expeditious use of computer simulations of crash impact. Unlike automotive impact testing, which is now routine, experimental crash tests of even small aircraft are expensive and complex due to the high cost of the aircraft and the myriad of crash impact conditions that must be considered. Ultimately, the goal is to utilize full-scale crash simulations of aircraft for design evaluation and certification. The objective of this publication is to describe "best practices" for modeling aircraft impact using explicit nonlinear dynamic finite element codes such as LS-DYNA, DYNA3D, and MSC.Dytran. Although "best practices" is somewhat relative, it is hoped that the authors' experience will help others to avoid some of the common pitfalls in modeling that are not documented in one single publication. In addition, a discussion of experimental data analysis, digital filtering, and test-analysis correlation is provided. Finally, some examples of aircraft crash simulations are described in several appendices following the main report.

  6. Systematic simulations of modified gravity: chameleon models

    SciTech Connect

    Brax, Philippe [Institut de Physique Theorique, CEA, IPhT, CNRS, URA 2306, F-91191Gif/Yvette Cedex (France); Davis, Anne-Christine [DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Li, Baojiu [Institute for Computational Cosmology, Department of Physics, Durham University, Durham DH1 3LE (United Kingdom); Winther, Hans A. [Institute of Theoretical Astrophysics, University of Oslo, 0315 Oslo (Norway); Zhao, Gong-Bo, E-mail: philippe.brax@cea.fr, E-mail: a.c.davis@damtp.cam.ac.uk, E-mail: baojiu.li@durham.ac.uk, E-mail: h.a.winther@astro.uio.no, E-mail: gong-bo.zhao@port.ac.uk [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX (United Kingdom)

    2013-04-01

    In this work we systematically study the linear and nonlinear structure formation in chameleon theories of modified gravity, using a generic parameterisation which describes a large class of models using only 4 parameters. For this we have modified the N-body simulation code ecosmog to perform a total of 65 simulations for different models and parameter values, including the default ?CDM. These simulations enable us to explore a significant portion of the parameter space. We have studied the effects of modified gravity on the matter power spectrum and mass function, and found a rich and interesting phenomenology where the difference with the ?CDM paradigm cannot be reproduced by a linear analysis even on scales as large as k ? 0.05 hMpc{sup ?1}, since the latter incorrectly assumes that the modification of gravity depends only on the background matter density. Our results show that the chameleon screening mechanism is significantly more efficient than other mechanisms such as the dilaton and symmetron, especially in high-density regions and at early times, and can serve as a guidance to determine the parts of the chameleon parameter space which are cosmologically interesting and thus merit further studies in the future.

  7. Beyond simple linear mixing models: process-based isotope partitioning of ecological processes.

    PubMed

    Ogle, Kiona; Tucker, Colin; Cable, Jessica M

    2014-01-01

    Stable isotopes are valuable tools for partitioning the components contributing to ecological processes of interest, such as animal diets and trophic interactions, plant resource use, ecosystem gas fluxes, streamflow, and many more. Stable isotope data are often analyzed with simple linear mixing (SLM) models to partition the contributions of different sources, but SLM models cannot incorporate a mechanistic understanding of the underlying processes and do not accommodate additional data associated with these processes (e.g., environmental covariates, flux data, gut contents). Thus, SLM models lack predictive ability. We describe a process-based mixing (PBM) model approach for integrating stable isotopes, other data sources, and process models to partition different sources or process components. This is accomplished via a hierarchical Bayesian framework that quantifies multiple sources of uncertainty and enables the incorporation of process models and prior information to help constrain the source-specific proportional contributions, thereby potentially avoiding identifiability issues that plague SLM models applied to "too many" sources. We discuss the application of the PBM model framework to three diverse examples: temporal and spatial partitioning of streamflow, estimation of plant rooting profiles and water uptake profiles (or water sources) with extension to partitioning soil and ecosystem CO2 fluxes, and reconstructing animal diets. These examples illustrate the advantages of the PBM modeling approach, which facilitates incorporation of ecological theory and diverse sources of information into the mixing model framework, thus enabling one to partition key process components across time and space. PMID:24640543

  8. Simulating temperature-dependent ecological processes at the sub-continental scale: male gypsy moth flight phenology as an example

    NASA Astrophysics Data System (ADS)

    Régnière, J.; Sharov, Alexei

    We simulated male gypsy moth flight phenology for the location of 1371 weather stations east of 100° W longitude and north of 35° N latitude in North America. The output of these simulations, based on average weather conditions from 1961 to 1990, was submitted to two map-interpolation methods: multiple regression and universal kriging. Multiple regression was found to be as accurate as universal kriging and demands less computing power. A map of the date of peak male gypsy moth flight was generated by universal kriging. This map itself constitutes a useful pest-management planning tool; in addition, the map delineates the potential range of the gypsy moth based on its seasonality at the northern edge of its current distribution in eastern North America. The simulation and map-interpolation methods described in this paper thus constitute an interesting approach to the study and monitoring of the ecological impacts of climate change and shifts in land-use patterns at the sub-continental level.

  9. EDITORIAL: Modelling and simulation in polymer and composites processing

    NASA Astrophysics Data System (ADS)

    Castro, Josè M.

    2004-05-01

    The general theme of this special section is modelling and simulation in polymer and composite processing. Composite processing in general involves reactive processing. During the last decade there have been numerous advances in modelling and simulation in both thermoplastic and reactive processing. This fact, coupled with the enormous advances in computing capability, has made Computer Aided Engineering (CAE) a reality. Industry nowadays depends on CAE to improve and/or develop new processes. There is no excuse not to take advantage of modelling and simulation. Another tendency is a clear move towards environmentally benign manufacturing; thus several papers in this issue discuss environmentally benign alternatives to traditional manufacturing for both composite and thermoplastics. The first two papers are a review of modelling and simulation; the first paper by Castro, Cabrera Rios and Mount-Campbell focuses on reactive processing, while the second by Kim and Turng discusses thermoplastics moulding. Another important issue is the need to use empirical modelling for cases where physics-based models are not available or are too cumbersome to use. For that reason the paper by Castro et al focuses on empirical modelling and the paper by Kim and Turng discusses exclusively physics-based modelling. The next three papers, two by Advani and collaborators and the third by Srinivasagupta and Kardos, refer to composite manufacturing. Advani's papers cover recent advances in Reactive Liquid Moulding, a process that has gained great acceptance as an environmentally benign alternative to open moulding. The paper by Srinivasagupta and Kardos covers the important issue of addressing simultaneously both environmental and economical design. In general the environmental optimum does not coincide with the economic optimum; this gives rise to the need to compromise. The Data Envelopment Analysis (DEA) technique, discussed in the first paper, can be used to identify the best set of compromises. The exergy approach used by Srinivasagupta and Kardos to evaluate the ecological impact has shown great potential for measuring the effect of processes in the environment. The process they discuss is an environmentally friendly alternative to the standard pultrusion process. The sixth paper, by Chensong Dong and collaborators, focuses on modelling and optimizing dimensional variation in composites, and offers a good complement to Advani's papers. Papers seven by Lilly et al, and eight by Lyytikainen et al, focus on thermoplastic moulding. The last paper, by Chen et al, discusses the modelling of a technology that has the potential to be the environmentally friendly alternative to painting. I would like to thank Dr Mauricio Cabrera Rios, who obtained his PhD under my supervision and is now a professor at the Universidad Autonoma de Nuevo Leon, Mexico, for his help in coordinating the paper reviews. Also, the willingness of the authors to go through several review iterations where needed is greatly appreciated. Finally I would like to thank Ms Judith Adams (editor), without whose help this issue would not have been possible. She was instrumental in securing some papers and in obtaining the proper evaluations of others.

  10. Mathematics analysis and chaos in an ecological model with an impulsive control strategy

    NASA Astrophysics Data System (ADS)

    Yu, Hengguo; Zhong, Shouming; Agarwal, Ravi P.

    2011-02-01

    In this paper, on the basis of the theories and methods of ecology and ordinary differential equation, an ecological model with an impulsive control strategy is established. By using the theories of impulsive equation, small amplitude perturbation skills and comparison technique, we get the condition which guarantees the global asymptotical stability of the lowest-level prey and mid-level predator eradication periodic solution. It is proved that the system is permanent. Further, influences of the impulsive perturbation on the inherent oscillation are studied numerically, which shows rich dynamics, such as period-doubling bifurcation, period-halving bifurcation, chaotic band, narrow or wide periodic window, chaotic crises,etc. Moreover, the computation of the largest Lyapunov exponent demonstrates the chaotic dynamic behavior of the model. At the same time, we investigate the qualitative nature of strange attractor by using Fourier spectra. All these results may be useful for study of the dynamic complexity of ecosystems.

  11. Simulation of flight control laws design using model predictive controllers

    Microsoft Academic Search

    Zhi-jun Yang; Xiao-hui Qi; Gan-lin Shan

    2009-01-01

    A Model Predictive Control strategy is proposed for the flight control laws design. The modified MPC controller block is applied to the autopilot. The simulation framework uses MATLAB's basic configuration and Aerosim Aeronautical Simulation Blockset which provides a complete set of tools for rapid development of 6 DoF nonlinear aircraft models. The Aerosonde UAV model is utilized in the simulations

  12. Timed Cell-DEVS: modelling and simulation of cell spaces

    E-print Network

    Wainer, Gabriel

    Timed Cell-DEVS: modelling and simulation of cell spaces GABRIEL WAINER AND NORBERT GIAMBIASI DEVS to build a set of tools for modelling and simulation of cell spaces. As a result, the approach allows-effective development of cellular models simulators could be achieved. INTRODUCTION In recent years, a wide number

  13. Simulation based Model Reduction with Proper Orthogonal Decomposition

    E-print Network

    Gugat, Martin

    Simulation based Model Reduction with Proper Orthogonal Decomposition a Maximilian Walther Chair - FAU) Simulation based Model Reduction with POD September 2011 1 / 1 #12;Outline M. Walther (AMII - FAU) Simulation based Model Reduction with POD September 2011 2 / 1 #12;Motivation Motivation M. Walther (AMII

  14. Models for naturally fractured, carbonate reservoir simulations

    SciTech Connect

    Tuncay, K.; Park, A.; Ozkan, G.; Zhan, X.; Ortoleva, P. [Indiana Univ., Bloomington, IN (United States); Hoak, T. [Kestrel Geoscience, Littleton, CO (United States); Sundberg, K. [Phillips Petroleum Co., Bartlesville, OK (United States)

    1998-12-31

    This report outlines the need for new tools for the simulation of fractured carbonate reservoirs. Several problems are identified that call for the development of new reservoir simulation physical models and numerical techniques. These include: karst and vuggy media wherein Darcy`s and traditional multi-phase flow laws do not apply; the need for predicting the preproduction state of fracturing and stress so that the later response of effective stress-dependent reservoirs can be predicted; and methods for predicting the fracturing and collapse of vuggy and karst reservoirs in response to draw-down pressure created during production. Specific research directions for addressing each problem are outlined and preliminary results are noted.

  15. Volumetric modeling in laser BPH therapy simulation.

    PubMed

    Zhang, Nan; Zhou, Xiangmin; Shen, Yunhe; Sweet, Robert

    2010-01-01

    In this paper, we introduce a novel application of volume modeling techniques on laser Benign Prostatic Hyperplasia (BPH) therapy simulation. The core technique in our system is an algorithm for simulating the tissue vaporization process by laser heating. Different from classical volume CSG operations, our technique takes experimental data as the guidance to determine the vaporization amount so that only a specified amount of tissue is vaporized in each time. Our algorithm uses a predictor-corrector strategy. First, we apply the classical CSG algorithm on a tetrahedral grid based distance field to estimate the vaporized tissue amount. Then, a volume-correction phase is applied on the distance field. To improve the performance, we further propose optimization approaches for efficient implementation. PMID:20975181

  16. Eco-Cultural Niche Modeling: New Tools for Reconstructing the Geography and Ecology of Past Human Populations

    E-print Network

    Wohlfarth, Barbara

    Eco-Cultural Niche Modeling: New Tools for Reconstructing the Geography and Ecology of Past Human variety of cultural mechanisms to deal with these conditions. In an effort to understand the in- #12;Eco

  17. An Evolutionary Ecological Approach to the Study of Learning Behavior Using a Robot-Based Model

    Microsoft Academic Search

    Elio Tuci; Matt Quinn; Inman Harvey

    2002-01-01

    We are interested in the construction of ecological models of the evolution of learning behavior using methodological tools developed in the field of evolutionary robotics. In this article, we explore the applicability of integrated (i.e., nonmodular) neural networks with fixed connection weights and simple “leaky-integrator” neurons as controllers for autonomous learning robots. In contrast to Yamauchi and Beer (1994a), we

  18. An Ecological Risk Model for Early Childhood Anxiety: The Importance of Early Child Symptoms and Temperament

    Microsoft Academic Search

    Nicholas D. Mian; Laurel Wainwright; Margaret J. Briggs-Gowan; Alice S. Carter

    2011-01-01

    Childhood anxiety is impairing and associated with later emotional disorders. Studying risk factors for child anxiety may\\u000a allow earlier identification of at-risk children for prevention efforts. This study applied an ecological risk model to address\\u000a how early childhood anxiety symptoms, child temperament, maternal anxiety and depression symptoms, violence exposure, and\\u000a sociodemographic risk factors predict school-aged anxiety symptoms. This longitudinal, prospective

  19. Quantitative Estimation Models and Their Application of Ecological Water Use at a Basin Scale

    Microsoft Academic Search

    Ranghui Wang; Xinmin Lu

    2009-01-01

    Ecological water use (EWU) is urgent in need in the lower reaches of Tarim River in China. Estimation of water amount for\\u000a EWU is depending on some parameters and modeling. EWU is mainly consists of two parts in no runoff area in the basin, i.e.\\u000a total water amount for restoration groundwater table and total stand water amount of the all

  20. An individual-based model of a tritrophic ecology

    Microsoft Academic Search

    Moshi Arthur Charnell

    2008-01-01

    A spatially explicit individual-based model for a predator, prey and plant ecosystem is considered. The movement of the individuals is solely based on nearest-neighbour attraction\\/repulsion and reproduction is asexual. In this simple model emergent spatial organization of the individuals into clusters or groups is present even though all the individuals (predators and prey) are intra-specifically repelled by each other. The

  1. Modeling And Simulation Tools For Education Reform

    NSDL National Science Digital Library

    Created by the Shodor Education Foundation, Inc., the Modeling And Simulation Tools for Education Reform (MASTER) provide useful educational tools that help students and teachers learn through observation and modeling activities. The Shodor Foundation worked in tandem with the National Center for Supercomputing Applications, George Mason University, and other educational organizations to craft these tools and visitors can access all eight of them here. The Fractal Modeling Tools are a good place to start as visitors can download the required software or take in some instructional materials, such as the interactive fractal microscope and the snowflake fractal generator. Other notable areas here include The Pit and the Pendulum, which offers the work of Edgar Allan Poe as a way to learn about better reading through computation.

  2. Multispectral system analysis through modeling and simulation

    NASA Technical Reports Server (NTRS)

    Malila, W. A.; Gleason, J. M.; Cicone, R. C.

    1977-01-01

    The design and development of multispectral remote sensor systems and associated information extraction techniques should be optimized under the physical and economic constraints encountered and yet be effective over a wide range of scene and environmental conditions. Direct measurement of the full range of conditions to be encountered can be difficult, time consuming, and costly. Simulation of multispectral data by modeling scene, atmosphere, sensor, and data classifier characteristics is set forth as a viable alternative, particularly when coupled with limited sets of empirical measurements. A multispectral system modeling capability is described. Use of the model is illustrated for several applications - interpretation of remotely sensed data from agricultural and forest scenes, evaluating atmospheric effects in Landsat data, examining system design and operational configuration, and development of information extraction techniques.

  3. Effects of noise on some dynamical models in ecology.

    PubMed

    Schaffer, W M; Ellner, S; Kot, M

    1986-01-01

    We investigate effects of random perturbations on the dynamics of one-dimensional maps (single species difference equations) and of finite dimensional flows (differential equations for n species). In particular, we study the effects of noise on the invariant measure, on the "correlation" dimension of the attractor, and on the possibility of detecting the nonlinear deterministic component by applying reconstruction techniques to the time series of population abundances. We conclude that adding noise to maps with a stable fixed-point obscures the underlying determinism. This turns out not to be the case for systems exhibiting complex periodic or chaotic motion, whose essential properties are more robust. In some cases, adding noise reveals deterministic structure which otherwise could not be observed. Simulations suggest that similar results hold for flows whose attractor is almost two-dimensional. PMID:3805908

  4. WATER SUPPLY SIMULATION MODEL. VOLUME 1. MODEL DEVELOPMENT

    EPA Science Inventory

    This three-volume report describes the development of a water supply simulation model (WSSM), a system of computer programs that allows for a systematic evaluation of the physical and economic characteristics of a water distribution system in a spatial framework. The WSSM concept...

  5. Towards more ecologically realistic scenarios of plant uptake modelling for chemicals: PAHs in a small forest.

    PubMed

    Terzaghi, Elisa; Zacchello, Gabriele; Scacchi, Marco; Raspa, Giuseppe; Jones, Kevin C; Cerabolini, Bruno; Di Guardo, Antonio

    2015-02-01

    The importance of plants in the accumulation of organic contaminants from air and soil was recognized to the point that even regulatory predictive approaches now include a vegetation compartment or sub-compartment. However, it has recently been shown that many of such approaches lack ecological realism to properly evaluate the dynamic of air/plant/soil exchange, especially when environmental conditions are subject to sudden variations of meteorological or ecological parameters. This paper focuses on the development of a fully dynamic scenario in which the variability of concentrations of selected chemicals in air and plant leaves was studied weekly and related to the corresponding meteorological and ecological parameters, to the evaluate their influence. To develop scenarios for modelling purposes, two different sampling campaigns were performed to measure temporal variability of: 1) polycyclic aromatic hydrocarbon (PAH) concentrations in air of a clearing and a forest site, as well as in leaves of two broadleaf species and 2) two important leaf and canopy traits, specific leaf area (SLA) and leaf area index (LAI). The aim was to evaluate in detail how the variability of meteorological and ecological parameters (SLA and LAI) can influence the uptake/release of organic contaminants by plants and therefore air concentrations. A principal component analysis demonstrated how both meteorological and ecological parameters jointly influence PAH air concentrations. SLA, LAI, as well as leaf density were showed to change over time and among species and to be directly proportional to leaf/canopy uptake rate. While hazelnut had the higher leaf uptake rate, maple became the most important species when considering the canopy uptake rate due to its higher LAI. Other species specific traits, such as the seasonal variation in production of new leaves and the timing of bud burst, were also shown to influence the uptake rate of PAHs by vegetation. PMID:25461034

  6. Case studies and mathematical models of ecological speciation. 1. Cichlids in a crater lake.

    PubMed

    Gavrilets, Sergey; Vose, Aaron; Barluenga, Marta; Salzburger, Walter; Meyer, Axel

    2007-07-01

    A recent study of a pair of sympatric species of cichlids in Lake Apoyo in Nicaragua is viewed as providing probably one of the most convincing examples of sympatric speciation to date. Here, we describe and study a stochastic, individual-based, explicit genetic model tailored for this cichlid system. Our results show that relatively rapid (<20,000 generations) colonization of a new ecological niche and (sympatric or parapatric) speciation via local adaptation and divergence in habitat and mating preferences are theoretically plausible if: (i) the number of loci underlying the traits controlling local adaptation, and habitat and mating preferences is small; (ii) the strength of selection for local adaptation is intermediate; (iii) the carrying capacity of the population is intermediate; and (iv) the effects of the loci influencing nonrandom mating are strong. We discuss patterns and timescales of ecological speciation identified by our model, and we highlight important parameters and features that need to be studied empirically to provide information that can be used to improve the biological realism and power of mathematical models of ecological speciation. PMID:17614905

  7. Simulation Modelling: Educational Development Roles for Learning Technologists.

    ERIC Educational Resources Information Center

    Riley, David

    2002-01-01

    Discusses computer assisted learning and simulation modeling from a United Kingdom perspective. Highlights include modeling with the DMS (Dynamic Modelling System); modeling with STELLA; learning and teaching simulation modeling; educational development roles for learning technologists; and a list of relevant Web sites. (Contains 52 references.)…

  8. ASAP applications of simulation modeling in a wafer fab

    Microsoft Academic Search

    Kishore Potti; A. Gupta

    2002-01-01

    The authors define 4 levels of complexity in simulation modeling: the ability of the models to predict bottlenecks in the fab, capability of the model to be used for strategic applications such as cycle time reduction, the simulation of complex dispatch rules using the model, and the capability of the model to predict operational output of the wafer fab that

  9. A physics-based MTO model for circuit simulation

    Microsoft Academic Search

    Y. Bai; A. Q. Huang

    2000-01-01

    This paper presents a comprehensive model of the MTO (MOS turn-off thyristor) based on the lumped-charge modeling technique. The model includes important effects such as avalanche breakdown, Auger recombination and conductivity modulation. The thermal effect is also included in this model. The model is implemented as a MAST template in the Saber simulator and is compared with numerical simulation

  10. Toy models for galaxy formation versus simulations

    NASA Astrophysics Data System (ADS)

    Dekel, A.; Zolotov, A.; Tweed, D.; Cacciato, M.; Ceverino, D.; Primack, J. R.

    2013-10-01

    We describe simple useful toy models for key processes of galaxy formation in its most active phase, at z > 1, and test the approximate expressions against the typical behaviour in a suite of high-resolution hydro-cosmological simulations of massive galaxies at z=4-1. We address in particular the evolution of (a) the total mass inflow rate from the cosmic web into galactic haloes based on the EPS approximation, (b) the penetration of baryonic streams into the inner galaxy, (c) the disc size, (d) the implied steady-state gas content and star formation rate (SFR) in the galaxy subject to mass conservation and a universal star formation law, (e) the inflow rate within the disc to a central bulge and black hole as derived using energy conservation and self-regulated Q ˜ 1 violent disc instability (VDI) and (f) the implied steady state in the disc and bulge. The toy models provide useful approximations for the behaviour of the simulated galaxies. We find that (a) the inflow rate is proportional to mass and to (1 + z)5/2, (b) the penetration to the inner halo is ˜50 per cent at z=4-2, (c) the disc radius is ˜5 per cent of the virial radius, (d) the galaxies reach a steady state with the SFR following the accretion rate into the galaxy, (e) there is an intense gas inflow through the disc, comparable to the SFR, following the predictions of VDI and (f) the galaxies approach a steady state with the bulge mass comparable to the disc mass, where the draining of gas by SFR, outflows and disc inflows is replenished by fresh accretion. Given the agreement with simulations, these toy models are useful for understanding the complex phenomena in simple terms and for back-of-the-envelope predictions.

  11. Modeling and simulation technology readiness levels.

    SciTech Connect

    Clay, Robert L.; Shneider, Max S.; Marburger, S. J.; Trucano, Timothy Guy

    2006-01-01

    This report summarizes the results of an effort to establish a framework for assigning and communicating technology readiness levels (TRLs) for the modeling and simulation (ModSim) capabilities at Sandia National Laboratories. This effort was undertaken as a special assignment for the Weapon Simulation and Computing (WSC) program office led by Art Hale, and lasted from January to September 2006. This report summarizes the results, conclusions, and recommendations, and is intended to help guide the program office in their decisions about the future direction of this work. The work was broken out into several distinct phases, starting with establishing the scope and definition of the assignment. These are characterized in a set of key assertions provided in the body of this report. Fundamentally, the assignment involved establishing an intellectual framework for TRL assignments to Sandia's modeling and simulation capabilities, including the development and testing of a process to conduct the assignments. To that end, we proposed a methodology for both assigning and understanding the TRLs, and outlined some of the restrictions that need to be placed on this process and the expected use of the result. One of the first assumptions we overturned was the notion of a ''static'' TRL--rather we concluded that problem context was essential in any TRL assignment, and that leads to dynamic results (i.e., a ModSim tool's readiness level depends on how it is used, and by whom). While we leveraged the classic TRL results from NASA, DoD, and Sandia's NW program, we came up with a substantially revised version of the TRL definitions, maintaining consistency with the classic level definitions and the Predictive Capability Maturity Model (PCMM) approach. In fact, we substantially leveraged the foundation the PCMM team provided, and augmented that as needed. Given the modeling and simulation TRL definitions and our proposed assignment methodology, we conducted four ''field trials'' to examine how this would work in practice. The results varied substantially, but did indicate that establishing the capability dependencies and making the TRL assignments was manageable and not particularly time consuming. The key differences arose in perceptions of how this information might be used, and what value it would have (opinions ranged from negative to positive value). The use cases and field trial results are included in this report. Taken together, the results suggest that we can make reasonably reliable TRL assignments, but that using those without the context of the information that led to those results (i.e., examining the measures suggested by the PCMM table, and extended for ModSim TRL purposes) produces an oversimplified result--that is, you cannot really boil things down to just a scalar value without losing critical information.

  12. Modelling and simulation of gyrotrons for ITER

    NASA Astrophysics Data System (ADS)

    Damyanova, M.; Kern, S.; Illy, S.; Thumm, M.; Sabchevski, S.; Zhelyazkov, I.; Vasileva, E.

    2014-06-01

    Powerful gyrotrons of the megawatt class will be used for electron cyclotron resonance heating (ECRH) and current drive (ECCD) of magnetically confined plasma in the thermonuclear reactor ITER. For computer-aided design (CAD), analysis and optimization of their performance numerical experiments based on adequate physical models are used. In this paper, we outline and illustrate the current status of both the available software tools for numerical simulation of such gyrotrons, as well as the novel computer codes of the problem oriented GYREOSS software package which is under development now.

  13. Author's personal copy Ecological Modelling 243 (2012) 1832

    E-print Network

    Hebblewhite, Mark

    2012-01-01

    navigating their landscape in winter. The ABM model is composed of cognitive caribou agents possess- ing and predator/disturbance avoidance. A set of environmental data layers was used to develop a virtual grid, the relative extent to which they perceive industry features as potential predation, and the differential

  14. Ecological utilization of leather tannery waste with circular economy model

    Microsoft Academic Search

    Jing Hu; Zuobing Xiao; Rujun Zhou; Weijun Deng; Mingxi Wang; Shuangshuang Ma

    2011-01-01

    Circular economy (CE) focuses on resource-productivity and eco-efficiency improvement in a comprehensive way, especially on the industrial structure optimization of new technology development and application, equipment renewal and management renovation. The leather industry on the one side boosts the local economic development, on the other side however leads to the tremendous environment pollution and biological chains destruction. The CE model

  15. Ecological Models and Methods in the Study of School Psychology.

    ERIC Educational Resources Information Center

    Scott, Myrtle

    School psychology is a very complex field further complicated by current socio-political contexts which mandate the development of a psychology of school psychology, requiring two things as first steps. The first step is a model which outlines the conceptual map of the area, gives direction to investigations in the area, and checks on the…

  16. Cognitive Niches: An Ecological Model of Strategy Selection

    ERIC Educational Resources Information Center

    Marewski, Julian N.; Schooler, Lael J.

    2011-01-01

    How do people select among different strategies to accomplish a given task? Across disciplines, the strategy selection problem represents a major challenge. We propose a quantitative model that predicts how selection emerges through the interplay among strategies, cognitive capacities, and the environment. This interplay carves out for each…

  17. Multi-objective optimization of an ecological assembly model

    E-print Network

    Coello, Carlos A. Coello

    assembly models, species are introduced from a pool of species according to a sequence of invasion that the invasive species have on the community are the extinction of invasive species with or without sec- ondary, certain sequences can lead to communities with a complete resistance to invasion by other species

  18. Management of marine construction works using ecological modelling

    NASA Astrophysics Data System (ADS)

    Bach, H. K.; Jensen, K.; Lyngby, J. E.

    1997-01-01

    A system of bridges and tunnels between Denmark and Sweden is being constructed. The environmental management of the dredging and reclamation work includes planning using a mathematical model which can forecast the effect of different spill scenarios in order to minimize adverse effects on eelgrass beds. To develop the model, plots of eelgrass beds (4 m 2) were covered with nets excluding 30, 60 and 90% of the light. Shoot density, leaf and root/rhizome biomass, and soluble carbohydrates in roots and rhizomes were observed in order to determine the response of the plants to shading. In selected plots, all aboveground biomass was harvested to assess the re-growth potential. The minimum level of soluble carbohydrates necessary for securing re-growth was 60-90 mg g -1. The inclusion of the subsediment parts of the eelgrass permits model runs beyond one growth season, and the prediction of re-growth after subsequent shading and winter dormancy. The model has been satisfyingly calibrated and validated. A feedback monitoring system has been developed based on field studies of eelgrass variables, a set of pre-fixed environmental criteria and forecasting of the effects of the construction works. The system facilitates planning and management of the dredging and reclamation operations, and mitigating actions during the progression of the work.

  19. Modeling VOC transport in simulated waste drums

    SciTech Connect

    Liekhus, K.J.; Gresham, G.L.; Peterson, E.S.; Rae, C.; Hotz, N.J.; Connolly, M.J.

    1993-06-01

    A volatile organic compound (VOC) transport model has been developed to describe unsteady-state VOC permeation and diffusion within a waste drum. Model equations account for three primary mechanisms for VOC transport from a void volume within the drum. These mechanisms are VOC permeation across a polymer boundary, VOC diffusion across an opening in a volume boundary, and VOC solubilization in a polymer boundary. A series of lab-scale experiments was performed in which the VOC concentration was measured in simulated waste drums under different conditions. A lab-scale simulated waste drum consisted of a sized-down 55-gal metal drum containing a modified rigid polyethylene drum liner. Four polyethylene bags were sealed inside a large polyethylene bag, supported by a wire cage, and placed inside the drum liner. The small bags were filled with VOC-air gas mixture and the VOC concentration was measured throughout the drum over a period of time. Test variables included the type of VOC-air gas mixtures introduced into the small bags, the small bag closure type, and the presence or absence of a variable external heat source. Model results were calculated for those trials where the VOC permeability had been measured. Permeabilities for five VOCs [methylene chloride, 1,1,2-trichloro-1,2,2-trifluoroethane (Freon-113), 1,1,1-trichloroethane, carbon tetrachloride, and trichloroethylene] were measured across a polyethylene bag. Comparison of model and experimental results of VOC concentration as a function of time indicate that model accurately accounts for significant VOC transport mechanisms in a lab-scale waste drum.

  20. Modeling, simulation and control of crude towers

    SciTech Connect

    Hsie, W.L.

    1989-01-01

    A crude tower which separates crude oil into various petroleum fractions, is one of the most complex units in the refining industry. A mathematical model for the rigorous dynamic simulation of a crude tower is developed. The non-linear, coupled modeling equations of a crude tower form a very large set of stiff ordinary differential and algebraic equations. The large dimension and stiffness make the simulation very time consuming. A new model, which is based on a separated component concept, is shown to be able to reduce the dimension and stiffness of the system, and save a large amount of computer time. Several authors who tried to apply the bubble point algorithm (BPA) to solve the modeling equations of crude towers reported difficulties with convergence. In this research, it is shown that the bubble point temperature is extremely sensitive to the error in liquid composition of the components with a wide range of volatility. This sensitivity causes numerical instability of the BPA. The sum of rates algorithm (SRA) is shown to be more suitable for computing the steady state conditions of a crude tower by solving the modeling equations. Once an initial steady-state is reached, the transient responses of the crude tower can be obtained by BPA. The main objective of crude tower control is to maximize the production of more valuable products from the crude feed. This maximization can be accomplished by an effective product quality and pump around control scheme. A computer control algorithm, Quadratic Dynamic Matrix Control (QDMC), is applied to the control of a crude tower. Due to the multivariable and predictive nature of the QDMC algorithm, it handles the interactions of the product quality very effectively.

  1. Distributed Slip Model for Simulating Virtual Earthquakes

    NASA Astrophysics Data System (ADS)

    Shani-Kadmiel, S.; Tsesarsky, M.; Gvirtzman, Z.

    2014-12-01

    We develop a physics based, generic finite fault source, which we call the Distributed Slip Model (DSM) for simulating large virtual earthquakes. This task is a necessary step towards ground motion prediction in earthquake-prone areas with limited instrumental coverage. A reliable ground motion prediction based on virtual earthquakes must account for site, path, and source effects. Assessment of site effect mainly depends on near-surface material properties which are relatively well constrained, using geotechnical site data and borehole measurements. Assessment of path effect depends on the deeper geological structure, which is also typically known to an acceptable resolution. Contrarily to these two effects, which remain constant for a given area of interest, the earthquake rupture process and geometry varies from one earthquake to the other. In this study we focus on a finite fault source representation which is both generic and physics-based, for simulating large earthquakes where limited knowledge is available. Thirteen geometric and kinematic parameters are used to describe the smooth "pseudo-Gaussian" slip distribution, such that slip decays from a point of peak slip within an elliptical rupture patch to zero at the borders of the patch. Radiation pattern and spectral charectaristics of our DSM are compared to those of commonly used finite fault models, i.e., the classical Haskell's Model (HM) and the modified HM with Radial Rupture Propagation (HM-RRP) and the Point Source Model (PSM). Ground motion prediction based on our DSM benefits from the symmetry of the PSM and the directivity of the HM while overcoming inadequacy for modeling large earthquakes of the former and the non-physical uniform slip of the latter.

  2. Modeling, Simulation, and Forecasting of Subseasonal Variability

    NASA Technical Reports Server (NTRS)

    Waliser, Duane; Schubert, Siegfried; Kumar, Arun; Weickmann, Klaus; Dole, Randall

    2003-01-01

    A planning workshop on "Modeling, Simulation and Forecasting of Subseasonal Variability" was held in June 2003. This workshop was the first of a number of meetings planned to follow the NASA-sponsored workshop entitled "Prospects For Improved Forecasts Of Weather And Short-Term Climate Variability On Sub-Seasonal Time Scales" that was held April 2002. The 2002 workshop highlighted a number of key sources of unrealized predictability on subseasonal time scales including tropical heating, soil wetness, the Madden Julian Oscillation (MJO) [a.k.a Intraseasonal Oscillation (ISO)], the Arctic Oscillation (AO) and the Pacific/North American (PNA) pattern. The overarching objective of the 2003 follow-up workshop was to proceed with a number of recommendations made from the 2002 workshop, as well as to set an agenda and collate efforts in the areas of modeling, simulation and forecasting intraseasonal and short-term climate variability. More specifically, the aims of the 2003 workshop were to: 1) develop a baseline of the "state of the art" in subseasonal prediction capabilities, 2) implement a program to carry out experimental subseasonal forecasts, and 3) develop strategies for tapping the above sources of predictability by focusing research, model development, and the development/acquisition of new observations on the subseasonal problem. The workshop was held over two days and was attended by over 80 scientists, modelers, forecasters and agency personnel. The agenda of the workshop focused on issues related to the MJO and tropicalextratropical interactions as they relate to the subseasonal simulation and prediction problem. This included the development of plans for a coordinated set of GCM hindcast experiments to assess current model subseasonal prediction capabilities and shortcomings, an emphasis on developing a strategy to rectify shortcomings associated with tropical intraseasonal variability, namely diabatic processes, and continuing the implementation of an experimental forecast and model development program that focuses on one of the key sources of untapped predictability, namely the MJO. The tangible outcomes of the meeting included: 1) the development of a recommended framework for a set of multi-year ensembles of 45-day hindcasts to be carried out by a number of GCMs so that they can be analyzed in regards to their representations of subseasonal variability, predictability and forecast skill, 2) an assessment of the present status of GCM representations of the MJO and recommendations for future steps to take in order to remedy the remaining shortcomings in these representations, and 3) a final implementation plan for a multi-institute/multi-nation Experimental MJO Prediction Program.

  3. Great Basin Land Management Planning Using Ecological Modeling

    NASA Astrophysics Data System (ADS)

    Forbis, Tara A.; Provencher, Louis; Frid, Leonardo; Medlyn, Gary

    2006-07-01

    This report describes a land management modeling effort that analyzed potential impacts of proposed actions under an updated Bureau of Land Management Resource Management Plan that will guide management for 20 years on 4.6 million hectares in the Great Basin ecoregion of the United States. State-and-transition models that included vegetation data, fire histories, and many parameters (i.e., rates of succession, fire return intervals, outcomes of management actions, and invasion rates of native and nonnative invasive species) were developed through workshops with scientific experts and range management specialists. Alternative restoration scenarios included continuation of current management, full fire suppression, wildfire use in designated fire use zones, wildfire use in resilient vegetation types only, restoration with a tenfold budget increase, no restoration treatments, and no livestock grazing. Under all the scenarios, cover of vegetation states with native perennial understory declined and was replaced by tree-invaded and weed-dominated states. The greatest differences among alternative management scenarios resulted from the use of fire as a tool to maintain native understory. Among restoration scenarios, only the scenario assuming a tenfold budget increase had a more desirable outcome than the current management scenario. Removal of livestock alone had little effect on vegetation resilience. Rather, active restoration was required. The predictive power of the model was limited by current understanding of Great Basin vegetation dynamics and data needs including statistically valid monitoring of restoration treatments, invasiveness and invasibility, and fire histories. The authors suggest that such computer models can be useful tools for systematic analysis of potential impacts in land use planning. However, for a modeling effort to be productive, the management situation must be conducive to open communication among land management agencies and partner entities, including nonprofit organizations.

  4. Orion Landing Simulation Eight Soil Model Comparison

    NASA Technical Reports Server (NTRS)

    Mark, Stephen D.

    2009-01-01

    LS-DYNA finite element simulations of a rigid Orion Crew Module (CM) were used to investigate the CM impact behavior on eight different soil models. Ten different landing conditions, characterized by the combination of CM vertical and horizontal velocity, hang angle, and roll angle were simulated on the eight different soils. The CM center of gravity accelerations, pitch angle, kinetic energy, and soil contact forces were the outputs of interest. The simulation results are presented, with comparisons of the CM behavior on the different soils. The soils analyzed in this study can be roughly categorized as soft, medium, or hard, according to the CM accelerations that occur when landing on them. The soft group is comprised of the Carson Sink Wet soil and the Kennedy Space Center (KSC) Low Density Dry Sand. The medium group includes Carson Sink Dry, the KSC High Density In-Situ Moisture Sand and High Density Flooded Sand, and Cuddeback B. The hard soils are Cuddeback A and the Gantry Unwashed Sand. The softer soils were found to produce lower peak accelerations, have more stable pitch behavior, and to be less sensitive to the landing conditions. This investigation found that the Cuddeback A soil produced the highest peak accelerations and worst stability conditions, and that the best landing performance was achieved on the KSC Low Density Dry Sand.

  5. Nutritional models for a Controlled Ecological Life Support System (CELSS): Linear mathematical modeling

    NASA Technical Reports Server (NTRS)

    Wade, Rose C.

    1989-01-01

    The NASA Controlled Ecological Life Support System (CELSS) Program is involved in developing a biogenerative life support system that will supply food, air, and water to space crews on long-duration missions. An important part of this effort is in development of the knowledge and technological capability of producing and processing foods to provide optimal diets for space crews. This involves such interrelated factors as determination of the diet, based on knowledge of nutrient needs of humans and adjustments in those needs that may be required as a result of the conditions of long-duration space flight; determination of the optimal mixture of crops required to provide nutrients at levels that are sufficient but not excessive or toxic; and consideration of the critical issues of spacecraft space and power limitations, which impose a phytomass minimization requirement. The complex interactions among these factors are examined with the goal of supplying a diet that will satisfy human needs while minimizing the total phytomass requirement. The approach taken was to collect plant nutritional composition and phytomass production data, identify human nutritional needs and estimate the adjustments to the nutrient requirements likely to result from space flight, and then to generate mathematical models from these data.

  6. Modeling and Simulation Methods for Design of Engineering Systems

    Microsoft Academic Search

    Rajarishi Sinha; Christiaan J. J. Paredis; Vei-chung Liang; Pradeep K. Khosla

    2001-01-01

    This article presents an overview of the state-of-the art in modeling and simulation, and studies to which extent current simulation technologies can effectively support the design process. For simulation-based design, modeling languages and simulation environments must take into account the special characteristics of the design process. For instance, languages should allow models to be easily updated and extended to accommodate

  7. Multiple Time Series Ising Model for Financial Market Simulations

    NASA Astrophysics Data System (ADS)

    Takaishi, Tetsuya

    2015-01-01

    In this paper we propose an Ising model which simulates multiple financial time series. Our model introduces the interaction which couples to spins of other systems. Simulations from our model show that time series exhibit the volatility clustering that is often observed in the real financial markets. Furthermore we also find non-zero cross correlations between the volatilities from our model. Thus our model can simulate stock markets where volatilities of stocks are mutually correlated.

  8. From local interactions to population dynamics in site-based models of ecology.

    PubMed

    Johansson, A; Sumpter, D J T

    2003-12-01

    A central problem in ecology is relating the interactions of individuals-described in terms of competition, predation, interference, etc.-to the dynamics of the populations of these individuals-in terms of change in numbers of individuals over time. Here, we address this problem for a class of site-based ecological models, where local interactions between individuals take place at a finite number of discrete resource sites over non-overlapping generations and, between generations, individuals move randomly between sites over the entire system. Such site-based models have previously been applied to a wide range of ecological systems: from those involving contest or scramble competition for resources to host-parasite interactions and meta-populations. We show how the population dynamics of site-based models can be accurately approximated by and understood through deterministic and stochastic difference equations. Conversely, we use the inverse of this approximation to show what implicit assumptions are made about individual interactions by modelling of population dynamics in terms of difference equations. To this end, we prove a useful and general theorem: that any model in our class of site-based models has a corresponding stochastic difference equation population model, by which it can be approximated. This theorem allows us to calculate long-term population dynamics, evolutionary stable strategies and, by extending our theory to account for large deviations, extinction probabilities for a wide range of site-based systems. Our methodology is then illustrated to various examples of between species competition, predator-prey interactions and co-operation. PMID:14630485

  9. SIMULATION MODELING AND ANALYSIS OF OVERNIGHT VISITOR USE OF THE YOSEMITE

    E-print Network

    Martin, Steven

    SIMULATION MODELING AND ANALYSIS OF OVERNIGHT VISITOR USE OF THE YOSEMITE WILDERNESS Final Report ..............................................................................................................................1 Computer Simulation Modeling......................................................................10 Yosemite Wilderness Use Simulation Model

  10. Radiation, Ecology and the Invalid LNT Model: The Evolutionary Imperative

    PubMed Central

    Parsons, Peter A.

    2006-01-01

    Metabolic and energetic efficiency, and hence fitness of organisms to survive, should be maximal in their habitats. This tenet of evolutionary biology invalidates the linear-nothreshold (LNT) model for the risk consequences of environmental agents. Hormesis in response to selection for maximum metabolic and energetic efficiency, or minimum metabolic imbalance, to adapt to a stressed world dominated by oxidative stress should therefore be universal. Radiation hormetic zones extending substantially beyond common background levels, can be explained by metabolic interactions among multiple abiotic stresses. Demographic and experimental data are mainly in accord with this expectation. Therefore, non-linearity becomes the primary model for assessing risks from low-dose ionizing radiation. This is the evolutionary imperative upon which risk assessment for radiation should be based. PMID:18648598

  11. Coupling Ecology and River Dynamics using a Simplified Interaction Model

    NASA Astrophysics Data System (ADS)

    Longjas, A.; Czuba, J. A.; Schwenk, J.; Danesh Yazdi, M.; Hansen, A.; Foufoula-Georgiou, E.

    2013-12-01

    Quantifying how changes in streamflow and sediment affect riverine life is an important component of river basin management and stream restoration efforts, especially under human and climate-induced changes affecting many basins around the world. In the Midwestern US, drastic changes in mussel populations have been witnessed over the past decade begging quantitative understanding of cause and effect and attribution of these changes to the concurrent changes in streamflow and sediment loads to the rivers. Previous empirical analyses have attempted to explore mussel abundance with habitat associations and bulk hydrologic and geomorphic attributes as predictors but results showed relatively weak relationships and low predictive power. In this work, we developed a process-based model that incorporates water-sediment-mussel interactions using functional relationships and predicts the long-term trends of suspended-sediment, chlorophyll-a and mussel population using a daily streamflow record. We applied the model to the Minnesota River Basin, which has experienced significant changes in precipitation and runoff, increased sediment delivery, and decreasing mussel populations. Our model captures the general dynamics of the system and provides a better predictor of mussel populations than predictions based on geomorphic (e.g. upstream drainage area, slope) and hydraulic variables (e.g. 2-year recurrence interval peak streamflow, depth, width, cross sectional area, velocity, and Froude number) alone. To highlight the utility of our model, we tested possible scenarios that illustrate (1) how climate and land-use change may undermine the resilience of mussel populations and (2) how management efforts can allow mussel populations to recover.

  12. Simulation Models for Robust Design Using Location Depth Methods

    E-print Network

    Stadlober, Ernst

    Simulation Models for Robust Design Using Location Depth Methods Ernst Stadlober Institute is described as the range of simulation (SPICE) parameters, but to reduce the costs of simulation- ping. To increase the robustness of the simulation the region covered by the set of boundary points

  13. Pattern-oriented modelling: a ‘multi-scope’ for predictive systems ecology

    PubMed Central

    Grimm, Volker; Railsback, Steven F.

    2012-01-01

    Modern ecology recognizes that modelling systems across scales and at multiple levels—especially to link population and ecosystem dynamics to individual adaptive behaviour—is essential for making the science predictive. ‘Pattern-oriented modelling’ (POM) is a strategy for doing just this. POM is the multi-criteria design, selection and calibration of models of complex systems. POM starts with identifying a set of patterns observed at multiple scales and levels that characterize a system with respect to the particular problem being modelled; a model from which the patterns emerge should contain the right mechanisms to address the problem. These patterns are then used to (i) determine what scales, entities, variables and processes the model needs, (ii) test and select submodels to represent key low-level processes such as adaptive behaviour, and (iii) find useful parameter values during calibration. Patterns are already often used in these ways, but a mini-review of applications of POM confirms that making the selection and use of patterns more explicit and rigorous can facilitate the development of models with the right level of complexity to understand ecological systems and predict their response to novel conditions. PMID:22144392

  14. Computer simulation model of swine production systems: III. A dynamic herd simulation model including reproduction.

    PubMed

    Pomar, C; Harris, D L; Savoie, P; Minvielle, F

    1991-07-01

    A dynamic herd simulation model for a swine production unit has been developed. The model is discrete and stochastic and the appropriate random distributions have been defined from the literature or empirically estimated. Theoretical concepts and relationships presented previously are used to simulate growth and the overall life cycle of individual animals. Simulated animals are young pigs (from birth to slaughter age), gilts, and sows. Animal events are farrowing, weaning, mating, end-nursery (transfer from nursery to the growing-finishing facility), and slaughter and are processed individually using a next-event scheduling orientation package. Animals within the herd are culled for different health and reproductive reasons. Genetic parameters, diet composition, and herd management are input variables chosen by the user. The effects of nutrition, genetics, season, and other factors on several reproductive parameters are considered. Model evaluation is performed by studying the output of the model under specified herd situations. The herd model adequately simulates animal flow and dynamics of the herd. PMID:1885394

  15. Integrated Modeling for the Assessment of Ecological Impacts of Sea Level Rise

    NASA Astrophysics Data System (ADS)

    Hagen, S. C.; Lewis, G.; Bartel, R.; Batten, B.; Huang, W.; Morris, J.; Slinn, D. N.; Sparks, J.; Walters, L.; Wang, D.; Weishampel, J.; Yeh, G.

    2010-12-01

    Sea level rise (SLR) has the potential to affect a variety of coastal habitats with a myriad of deleterious ecological effects and to overwhelm human settlements along the coast. SLR should be given serious consideration when more than half of the U.S. population lives within 50 miles of the coast. SLR effects will be felt along coastal beaches and in estuarine waters, with consequences to barrier islands, submerged aquatic vegetation beds, sand and mud flats, oyster reefs, and tidal and freshwater wetlands. Managers of these coastal resources must be aware of potential consequences of SLR and adjust their plans accordingly to protect and preserve the resources under their care. The Gulf Coast provides critical habitats for a majority of the commercially important species in the Gulf of Mexico, which depend on inshore waters for either permanent residence or nursery area. The ecosystem services provided by these coastal habitats are at risk from rising sea level. Our team will assess the risk to coasts and coastal habitats from SLR in a 5-year project. We will apply existing models of circulation and transport from the watershed to the sea. The ultimate prediction will be of sediment loadings to the estuary as a result of overland flow, shoreline and barrier island erosion, and salinity transport, all of which will be used to model the evolution of intertidal marshes (MEM II). Over the five-year course of our research we will be simulating hydrodynamics and transport for all three NERRS reserves, including: Apalachicola, Weeks Bay and Grand Bay. The project will result in products whereby managers will be able to assess marshes, oyster reefs, submerged aquatic vegetation, predict wetland stability and indentify restoration locations for marsh and oyster habitats. In addition, we will produce Decision Support tools that will enable managers to predict future coastal erosion rates for management-specified shorelines. Project outcomes will enable the management community to prioritize risk management strategies, reformulate set back requirements, improve guidelines for construction of breakwaters and other coastal infrastructure, and assess water resources impacts and protection needs.

  16. A Prototypical Simulation Model to Analyze the Business Process Performance

    NASA Astrophysics Data System (ADS)

    Schmietendorf, Andreas; End, Andreas

    The paper deals with simulation possibilities used for the capacity management of business processes. After a selection process of several simulation tools, the AnyLogic framework is used to implement a prototype. Within this paper, the focus is on the conception and implementation phase of the simulation model. The multi-layered structure of the simulation model is shown, as well as selected implementation details of corresponding resources. Furthermore the author's vision of an integrated simulation environment is introduced. This allows the integration with process modelling tools, configurable interfaces for a parameter transfer and the automation of simulation experiments.

  17. VISION: Verifiable Fuel Cycle Simulation Model

    SciTech Connect

    Jacob J. Jacobson; Abdellatif M. Yacout; Gretchen E. Matthern; Steven J. Piet; David E. Shropshire

    2009-04-01

    The nuclear fuel cycle is a very complex system that includes considerable dynamic complexity as well as detail complexity. In the nuclear power realm, there are experts and considerable research and development in nuclear fuel development, separations technology, reactor physics and waste management. What is lacking is an overall understanding of the entire nuclear fuel cycle and how the deployment of new fuel cycle technologies affects the overall performance of the fuel cycle. The Advanced Fuel Cycle Initiative’s systems analysis group is developing a dynamic simulation model, VISION, to capture the relationships, timing and delays in and among the fuel cycle components to help develop an understanding of how the overall fuel cycle works and can transition as technologies are changed. This paper is an overview of the philosophy and development strategy behind VISION. The paper includes some descriptions of the model and some examples of how to use VISION.

  18. VISION: Verifiable Fuel Cycle Simulation Model

    SciTech Connect

    Jacob Jacobson; A. M. Yacout; Gretchen Matthern; Steven Piet; David Shropshire; Tyler Schweitzer

    2010-11-01

    The nuclear fuel cycle consists of a set of complex components that work together in unison. In order to support the nuclear renaissance, it is necessary to understand the impacts of changes and timing of events in any part of the fuel cycle system. The Advanced Fuel Cycle Initiative’s systems analysis group is developing a dynamic simulation model, VISION, to capture the relationships, timing, and changes in and among the fuel cycle components to help develop an understanding of how the overall fuel cycle works. This paper is an overview of the philosophy and development strategy behind VISION. The paper includes some descriptions of the model components and some examples of how to use VISION.

  19. Modeling and visual simulation of Microalgae photobioreactor

    NASA Astrophysics Data System (ADS)

    Zhao, Ming; Hou, Dapeng; Hu, Dawei

    Microalgae is a kind of nutritious and high photosynthetic efficiency autotrophic plant, which is widely distributed in the land and the sea. It can be extensively used in medicine, food, aerospace, biotechnology, environmental protection and other fields. Photobioreactor which is important equipment is mainly used to cultivate massive and high-density microalgae. In this paper, based on the mathematical model of microalgae which grew under different light intensity, three-dimensional visualization model was built and implemented in 3ds max, Virtools and some other three dimensional software. Microalgae is photosynthetic organism, it can efficiently produce oxygen and absorb carbon dioxide. The goal of the visual simulation is to display its change and impacting on oxygen and carbon dioxide intuitively. In this paper, different temperatures and light intensities were selected to control the photobioreactor, and dynamic change of microalgal biomass, Oxygen and carbon dioxide was observed with the aim of providing visualization support for microalgal and photobioreactor research.

  20. A critical appraisal of model simulations

    SciTech Connect

    MacCracken, M.C.

    1990-02-01

    The complexity of the climate system and the absence of definitive analogs to the evolving climatic situation force use of theoretical models to project the future climatic influence of the relatively rapid and on-going increase in the atmospheric concentrations of CO{sub 2} and other trace gases. The most comprehensive of the available climate models are known as General Circulation Models (GCMs). These models represent what are believed to be the most important components of atmosphere, ocean, and cryosphere system relevant to determining the potential for an enhanced greenhouse effect. Two types of studies are performed to study the potential consequences of the increasing concentrations of greenhouse gases. In the first, the gas concentration (usually CO{sub 2}) is arbitrarily and instantaneously increased and the model is run until a new equilibrium climate is reached, the difference between the perturbed and control results being a measure of the sensitivity of the climate to the imposed perturbation. In the second type of simulation, the gas concentration is slowly increased as time advances. 1 tab.

  1. System of systems modeling and simulation.

    SciTech Connect

    Lawton, Craig R.; Campbell, James E.; Anderson, Dennis James; Thompson, Bruce Miles; Longsine, Dennis E. (Intera, Inc., Austin, TX.); Shirah, Donald N.; Cranwell, Robert M.

    2005-02-01

    Analyzing the performance of a complex System of Systems (SoS) requires a systems engineering approach. Many such SoS exist in the Military domain. Examples include the Army's next generation Future Combat Systems 'Unit of Action' or the Navy's Aircraft Carrier Battle Group. In the case of a Unit of Action, a system of combat vehicles, support vehicles and equipment are organized in an efficient configuration that minimizes logistics footprint while still maintaining the required performance characteristics (e.g., operational availability). In this context, systems engineering means developing a global model of the entire SoS and all component systems and interrelationships. This global model supports analyses that result in an understanding of the interdependencies and emergent behaviors of the SoS. Sandia National Laboratories will present a robust toolset that includes methodologies for developing a SoS model, defining state models and simulating a system of state models over time. This toolset is currently used to perform logistics supportability and performance assessments of the set of Future Combat Systems (FCS) for the U.S. Army's Program Manager Unit of Action.

  2. At the Biological Modeling and Simulation Frontier

    PubMed Central

    Ropella, Glen E. P.; Lam, Tai Ning; Tang, Jonathan; Kim, Sean H. J.; Engelberg, Jesse A.; Sheikh-Bahaei, Shahab

    2009-01-01

    We provide a rationale for and describe examples of synthetic modeling and simulation (M&S) of biological systems. We explain how synthetic methods are distinct from familiar inductive methods. Synthetic M&S is a means to better understand the mechanisms that generate normal and disease-related phenomena observed in research, and how compounds of interest interact with them to alter phenomena. An objective is to build better, working hypotheses of plausible mechanisms. A synthetic model is an extant hypothesis: execution produces an observable mechanism and phenomena. Mobile objects representing compounds carry information enabling components to distinguish between them and react accordingly when different compounds are studied simultaneously. We argue that the familiar inductive approaches contribute to the general inefficiencies being experienced by pharmaceutical R&D, and that use of synthetic approaches accelerates and improves R&D decision-making and thus the drug development process. A reason is that synthetic models encourage and facilitate abductive scientific reasoning, a primary means of knowledge creation and creative cognition. When synthetic models are executed, we observe different aspects of knowledge in action from different perspectives. These models can be tuned to reflect differences in experimental conditions and individuals, making translational research more concrete while moving us closer to personalized medicine. Electronic supplementary material The online version of this article (doi:10.1007/s11095-009-9958-3) contains supplementary material, which is available to authorized users. PMID:19756975

  3. Ecological Niche Modeling to Estimate the Distribution of Japanese Encephalitis Virus in Asia

    PubMed Central

    Miller, Robin H.; Masuoka, Penny; Klein, Terry A.; Kim, Heung-Chul; Somer, Todd; Grieco, John

    2012-01-01

    Background Culex tritaeniorhynchus is the primary vector of Japanese encephalitis virus (JEV), a leading cause of encephalitis in Asia. JEV is transmitted in an enzootic cycle involving large wading birds as the reservoirs and swine as amplifying hosts. The development of a JEV vaccine reduced the number of JE cases in regions with comprehensive childhood vaccination programs, such as in Japan and the Republic of Korea. However, the lack of vaccine programs or insufficient coverage of populations in other endemic countries leaves many people susceptible to JEV. The aim of this study was to predict the distribution of Culex tritaeniorhynchus using ecological niche modeling. Methods/Principal Findings An ecological niche model was constructed using the Maxent program to map the areas with suitable environmental conditions for the Cx. tritaeniorhynchus vector. Program input consisted of environmental data (temperature, elevation, rainfall) and known locations of vector presence resulting from an extensive literature search and records from MosquitoMap. The statistically significant Maxent model of the estimated probability of Cx. tritaeniorhynchus presence showed that the mean temperatures of the wettest quarter had the greatest impact on the model. Further, the majority of human Japanese encephalitis (JE) cases were located in regions with higher estimated probability of Cx. tritaeniorhynchus presence. Conclusions/Significance Our ecological niche model of the estimated probability of Cx. tritaeniorhynchus presence provides a framework for better allocation of vector control resources, particularly in locations where JEV vaccinations are unavailable. Furthermore, this model provides estimates of vector probability that could improve vector surveillance programs and JE control efforts. PMID:22724030

  4. A coupled geomorphic and ecological model of tidal marsh evolution.

    PubMed

    Kirwan, Matthew L; Murray, A Brad

    2007-04-10

    The evolution of tidal marsh platforms and interwoven channel networks cannot be addressed without treating the two-way interactions that link biological and physical processes. We have developed a 3D model of tidal marsh accretion and channel network development that couples physical sediment transport processes with vegetation biomass productivity. Tidal flow tends to cause erosion, whereas vegetation biomass, a function of bed surface depth below high tide, influences the rate of sediment deposition and slope-driven transport processes such as creek bank slumping. With a steady, moderate rise in sea level, the model builds a marsh platform and channel network with accretion rates everywhere equal to the rate of sea-level rise, meaning water depths and biological productivity remain temporally constant. An increase in the rate of sea-level rise, or a reduction in sediment supply, causes marsh-surface depths, biomass productivity, and deposition rates to increase while simultaneously causing the channel network to expand. Vegetation on the marsh platform can promote a metastable equilibrium where the platform maintains elevation relative to a rapidly rising sea level, although disturbance to vegetation could cause irreversible loss of marsh habitat. PMID:17389384

  5. Simulation model for natural gas transmission pipeline network system

    Microsoft Academic Search

    Abraham Debebe Woldeyohannes; Mohd Amin Abd Majid

    2011-01-01

    This paper focuses on developing a simulation model for the analysis of transmission pipeline network system (TPNS) with detailed characteristics of compressor stations. Compressor station is the key element in the TPNS since it provides energy to keep the gas moving. The simulation model is used to create a system that simulates TPNS with different configurations to get pressure and

  6. GRIDMODELICA - A MODELING AND SIMULATION FRAMEWORK FOR THE GRID

    Microsoft Academic Search

    Kaj Nyström; Peter Aronsson; Peter Fritzson

    2004-01-01

    Simulation of complex models is a computationally expensive task. With the advent of grid com- puting, modelers can gain access to vast amounts of cheap computational power. This has however up until now required quite some effort to be put into specially written simulations in Fortran or C and also in the deployment of the simulation on the grid; a

  7. Parallel Simulation of a Stochastic Agent/Environment Interaction Model

    E-print Network

    Vialle, Stéphane

    interest for simulating complex systems (such as social ones, e.g. [14, 12], biological ones, e.g. [30 of such a model in case of simulating a set of mobile autonomous robots evolving in a structured environment1 Parallel Simulation of a Stochastic Agent/Environment Interaction Model Makram BOUZID 1 , Vincent

  8. Estimating population ecology models for the WWW market: evidence of competitive oligopolies.

    PubMed

    de Cabo, Ruth Mateos; Gimeno, Ricardo

    2013-01-01

    This paper proposes adapting a particle filtering algorithm to model online Spanish real estate and job search market segments based on the Lotka-Volterra competition equations. For this purpose the authors use data on Internet information searches from Google Trends to proxy for market share. Market share evolution estimations are coherent with those observed in Google Trends. The results show evidence of low website incompatibility in the markets analyzed. Competitive oligopolies are most common in such low-competition markets, instead of the monopolies predicted by theoretical ecology models under strong competition conditions. PMID:23244754

  9. On the application of multilevel modeling in environmental and ecological studies

    USGS Publications Warehouse

    Qian, S.S.; Cuffney, T.F.; Alameddine, I.; McMahon, G.; Reckhow, K.H.

    2010-01-01

    This paper illustrates the advantages of a multilevel/hierarchical approach for predictive modeling, including flexibility of model formulation, explicitly accounting for hierarchical structure in the data, and the ability to predict the outcome of new cases. As a generalization of the classical approach, the multilevel modeling approach explicitly models the hierarchical structure in the data by considering both the within- and between-group variances leading to a partial pooling of data across all levels in the hierarchy. The modeling framework provides means for incorporating variables at different spatiotemporal scales. The examples used in this paper illustrate the iterative process of model fitting and evaluation, a process that can lead to improved understanding of the system being studied. ?? 2010 by the Ecological Society of America.

  10. Modeling and Simulation of Glucose-Insulin Metabolism

    E-print Network

    Modeling and Simulation of Glucose-Insulin Metabolism Esben Friis-Jensen (s042244) Kongens Lyngby of the blood glucose and insulin kinetics. In this thesis one of the models, Bergman's minimal model is described trough derivation and simulations. It is a model consisting of a glucose and an insulin kinetics

  11. A taxonomy for simulation modeling based on programming language principles

    E-print Network

    Mukherjee, Amlan

    A taxonomy for simulation modeling based on programming language principles PAUL A. FISHWICK many diverse areas employ simulation models, no agreed-upon taxonomy has been developed to categorize than the design structure of the model. We present a uniform model design taxonomy whose categories

  12. Modeling and simulation of cascading contingencies

    NASA Astrophysics Data System (ADS)

    Zhang, Jianfeng

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

  13. Use of model discrimination techniques to improve hydrologic models under ecological constraints: the case of the Maggia Valley, Southern Switzerland

    NASA Astrophysics Data System (ADS)

    Foglia, L.; Mehl, S. W.; Hill, M. C.; Burlando, P.

    2009-04-01

    Model discrimination techniques are used to evaluate alternative conceptual models. Thorough consideration of alternative conceptual models is an important and often neglected step in the study of many natural systems, including groundwater systems. This means that many modelling efforts are less useful for system management than they could be because they exclude alternatives considered important by some stakeholders, which makes them vulnerable to criticism. Important steps include identifying reasonable alternative models and possibly using model averaging to improve predictions and measures of prediction uncertainty. Here we used the computer code MMA (Multi-Model Analysis) as a modelling tool to help: (1) model development, (2) make predictions, and (3) understand the physical processes most important to the system. We focus on the ability of a groundwater model constructed using MODFLOW to predict heads and flows in the Maggia Valley, Southern Switzerland, where connections between groundwater, surface water and ecology are of interest. Sixty-four alternative models were designed deterministically and differ in how the river, recharge, bedrock topography, and hydraulic conductivity are characterized. None of the models correctly represent heads and flows in the Northern and Southern part of the valley simultaneously. A cross-validation experiment was conducted to compare model discrimination results with the ability of the models to predict eight heads and three flows to the stream along three reaches midway along the valley where ecological consequences and, therefore, model accuracy are of great concern. Results suggest: (1) Model averaging appears to have improved prediction accuracy in the problem considered. (2) The most significant model improvements occurred with introduction of spatially distributed recharge and improved bedrock topography. (3) The simplest models poorly represented the system in the area of interest.

  14. Integrating data-driven ecological models in an expert-based decision support system for water management in the Du river basin (Vietnam).

    PubMed

    Hoang, Thu Huong; Mouton, Ans; Lock, Koen; De Pauw, Niels; Goethals, Peter L M

    2013-01-01

    In this study, classification trees were combined with the Water Framework Directive (WFD)-Explorer, a modular toolbox that supports integrated water management in a river basin to evaluate the impact of different restoration measures on river ecology. First, the WFD-Explorer toolbox analysed the effect of different restoration options on the abiotic river characteristics based on the water and substance balance embedded in the simulation environment. Based on these abiotic characteristics, the biological index Biological Monitoring Working Party for Vietnam was then predicted by classification trees that were trained on biological and abiotic data collected in the Du river basin in northern Vietnam. The ecological status of streams in the basin ranged from nearly pristine headwaters to severely impacted river stretches. Elimination of point sources from ore extraction and decentralised domestic wastewater treatment proved to be the most effective measures to improve the ecological condition of the Du river basin. The combination of the WFD-Explorer results with data-driven models enabled model application in a situation where expert knowledge was lacking. Consequently, this approach appeared promising for decision support in the context of river restoration and conservation management. PMID:22415845

  15. The Modeling and Simulation of Marine Air-condition

    Microsoft Academic Search

    Langtao Yan; Jingming Li; Derong Zhang; Chunjiang Liu

    2011-01-01

    To solve the air-condition simulator operational problems in IMO crew training, this paper, taking “Yu Kun” ship as the study object, established the air-condition cooler and compartment temperature dynamic mathematical model. With the Matlab\\/Simulink real-time simulation tools, reasonable and appropriate algorithm simulation parameters, it achieved the real-time dynamic Simulation on Marine air-condition. This simulation not only provided a powerful guarantee

  16. Modeling and simulation of turbulent multiphase flows

    NASA Astrophysics Data System (ADS)

    Li, Zhaorui

    The atomization of liquid spray in turbulent reacting and non-reacting flows usually occurs in two successive steps, i.e., primary breakup and secondary breakup. In the primary breakup region, the evolution of the interface between the phases is usually complex and very difficult to model. In the secondary breakup region, the average droplet size and volume occupied by the droplets are relatively small but the number of droplets is usually very significant. In this study, we use different mathematical and numerical models for different regions of the spray. For dense spray simulations, a coupled Lagrangian interface-tracking and Eulerian level set method is developed and implemented. In this method, the interface is identified based on the locations of notional particles and the geometrical information concerning the interface and fluid properties are obtained from the level set function. The level set function maintains a signed distance function via the particle-based Lagrangian re-initialization technique. Numerical simulations of several 'standard interface-moving' problems and two-fluid laminar and turbulent flows are conducted to assess this new hybrid method. The results of our analysis indicate that the hybrid particle-level set method can handle interfaces with complex shape change, and can accurately predict the interface values without any significant mass loss or gain. The results obtained for isotropic two-fluid turbulence via the new particle-level set method are validated by comparison with those obtained by the 'zero Mach number', variable-density method. The two-way interactions between the turbulent velocity field and the interface are studied by the particle-level set method. Extensive analysis of vorticity and energy equations indicates that the destabilization effect of turbulence and stability effect of surface tension on the interface motion and interface's effect on turbulence are strongly dependent on the density ratio and Weber number. For dilute spray simulations, a robust and efficient Eulerian-Lagrangian-Lagrangian mathematical/numerical LES model is employed. This is based on the filtered mass density function (FMDF) methodology and is applicable to two-phase turbulent reacting flows with two-way mass, momentum and energy coupling between phases included. In the LES/FMDF methodology, the "resolved" carrier gas velocity field is obtained by solving the filtered form of the compressible Navier-Stokes equations with a high-order finite difference scheme. The sugrid species, energy and combustion are modeled with the two-phase scalar FMDF transport equation, which is solved by a Lagrangian Monte Carlo method. The liquid droplet/spray is simulated with a non-equilibrium Lagrangian model and stochastic SGS closures. The two-way coupling is implemented through series of source/sink terms. The two-phase LES/FMDF is employed for systematic analysis of turbulent combustion in the double swirl spray burner and spray-controlled dump combustor for various flows and spray parameters. The effects of fuel type, spray/injection angle, mass loading ratio, droplet size and its distribution, fuel/air composition, wall, and other parameters on the combustion and turbulence are investigated.

  17. Ecological invasion, roughened fronts, and a competitor's extreme advance: integrating stochastic spatial-growth models.

    PubMed

    O'Malley, Lauren; Korniss, G; Caraco, Thomas

    2009-07-01

    Both community ecology and conservation biology seek further understanding of factors governing the advance of an invasive species. We model biological invasion as an individual-based, stochastic process on a two-dimensional landscape. An ecologically superior invader and a resident species compete for space preemptively. Our general model includes the basic contact process and a variant of the Eden model as special cases. We employ the concept of a "roughened" front to quantify effects of discreteness and stochasticity on invasion; we emphasize the probability distribution of the front-runner's relative position. That is, we analyze the location of the most advanced invader as the extreme deviation about the front's mean position. We find that a class of models with different assumptions about neighborhood interactions exhibits universal characteristics. That is, key features of the invasion dynamics span a class of models, independently of locally detailed demographic rules. Our results integrate theories of invasive spatial growth and generate novel hypotheses linking habitat or landscape size (length of the invading front) to invasion velocity, and to the relative position of the most advanced invader. PMID:19219509

  18. Ecological input-output modeling for embodied resources and emissions in Chinese economy 2005

    NASA Astrophysics Data System (ADS)

    Chen, Z. M.; Chen, G. Q.; Zhou, J. B.; Jiang, M. M.; Chen, B.

    2010-07-01

    For the embodiment of natural resources and environmental emissions in Chinese economy 2005, a biophysical balance modeling is carried out based on an extension of the economic input-output table into an ecological one integrating the economy with its various environmental driving forces. Included resource flows into the primary resource sectors and environmental emission flows from the primary emission sectors belong to seven categories as energy resources in terms of fossil fuels, hydropower and nuclear energy, biomass, and other sources; freshwater resources; greenhouse gas emissions in terms of CO2, CH4, and N2O; industrial wastes in terms of waste water, waste gas, and waste solid; exergy in terms of fossil fuel resources, biological resources, mineral resources, and environmental resources; solar emergy and cosmic emergy in terms of climate resources, soil, fossil fuels, and minerals. The resulted database for embodiment intensity and sectoral embodiment of natural resources and environmental emissions is of essential implications in context of systems ecology and ecological economics in general and of global climate change in particular.

  19. Modeling Ecologic and Geomorphic Change in Semi-Arid New Mexico

    NASA Astrophysics Data System (ADS)

    Collins, D. B.; Bras, R. L.

    2004-12-01

    A record of grazing, fire suppression and drought in the semi-arid American south-west since the 1800s has left a mark on the landscape. In the Pajarito Plateau, New Mexico, pinyon-juniper woodlands have expanded at the expense of ponderosa pine forest, giving rise to increased erosion rates - a concern to the sustainability of the soil resource and of vegetation. Soil loss also risks human exposure to contaminants from Los Alamos National Laboratory. The dynamics of this water-controlled environment arise from the complex interplay of climate, hydrology, ecology and geomorphology, an understanding of which is fundamental to solution of the environmental challenges. In an effort to predict the course of ecological and geomorphic change in the region, and to provide a tool for land-use planners in averting possible human health and environmental hazards, a numerical landscape evolution model is developed. It assimilates research encompassing plant physiology, ecology, hydrology, and geomorphology, highlights weaknesses in process understanding, and provides a prediction of the future environmental state on the time-scale of 100s of years.

  20. MODELING LAND USE CHANGE AND ITS ECOLOGICAL CONSEQUENCES IN THE PHOENIX METROPOLITAN REGION Jianguo Wu, John David, Darrel Jenerette, Matt Luck, and Sheryl Berling-Wolff

    E-print Network

    Hall, Sharon J.

    MODELING LAND USE CHANGE AND ITS ECOLOGICAL CONSEQUENCES IN THE PHOENIX METROPOLITAN REGION Jianguo land use change, multiple-scale analysis of the current urban landscape, spatial ecological footprint), (2) Land Use and Land Cover Change Modeling (a CA-Markov-GA model, a rule-based urban growth model