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1

Virtual Driving and Eco-Simulation VR City Modeling, Drive Simulation, and Ecological Habits  

E-print Network

Virtual Driving and Eco-Simulation VR City Modeling, Drive Simulation, and Ecological Habits@asu.edu Keywords: Drive Simulation, Traffic Visualization, Virtual Reality, Driving Behavior, Vehicle Emissions Abstract This paper introduces a VR city model developed for research in driving simulation, driver

2

Simulation of socio-ecological impacts: Modeling a fishing village  

NASA Astrophysics Data System (ADS)

The interrelationship of society and environment is addressed here through the study of a remote fishing village of 750 people. An interdisciplinary study evaluated demographic, economic, and social aspects of the community, and simulation modeling was used to integrate these societal characteristics with environmental factors. The population of the village had grown gradually until the 1960's, when a decline began. Out-migration correlated with declining fish harvests and with increased communications with urban centers. Fishing had provided the greatest economic opportunity, followed by logging. A survey was conducted to investigate the costs and revenues of village fishermen. Diversification characterized the local fleet, and analysis showed that rates of return on investment in the current year were equal between vessel types. The variable levels and rate parameters of the demographic, economic, and social components of the model were specified through static and time series data. Sensitivity analysis to assess the effects of uncertainty, and validation tests against known historical changes were also conducted. Forecast scenarios identified the development options under several levels of fish abundance and investment. The weight given to ecological versus economic resource management registered disproportionate effects due to the interaction between investment and migration rates and resource stochasticity. This finding argues against a “golden mean” rule for evaluating policy trade-offs and argues for the importance of using a dynamic, socio-ecological perspective in designing development policies for rural communities.

Miller, Philip C.

1982-03-01

3

An ecological economic simulation model of mountain fynbos ecosystems  

Microsoft Academic Search

Mountain fynbos ecosystems in South Africa are threatened by alien plant invasions and by a lack of funding for effective management of these invasions. This paper develops an ecological-economic argument for the effective management of plant invasions in mountain fynbos ecosystems. We do this by building a dynamic ecological economic model which values the ecosystem services that fynbos ecosystems provide

Steven I Higgins; Jane K Turpie; Robert Costanza; Richard M Cowling; Dave C Le Maitre; Christo Marais; Guy F Midgley

1997-01-01

4

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...

5

Ecological Modelling 180 (2004) 211229 A forest growth and biomass module for a landscape simulation  

E-print Network

Ecological Modelling 180 (2004) 211­229 A forest growth and biomass module for a landscape model. The combined model simulates disturbances (fire, wind, harvesting), dispersal, forest biomass and windthrow alter forest succession, living biomass and dead biomass across an artificial landscape

Mladenoff, David

6

Predicting waste stabilization pond performance using an ecological simulation model  

SciTech Connect

Waste stabilization ponds (lagoons) are often favored in small communities because of their low cost and ease of operation. Most models currently used to predict performance are empirical or fail to address the primary lagoon cell. Empirical methods for predicting lagoon performance have been found to be off as much as 248 percent when used on a system other than the one they were developed for. Also, the present models developed for the primary cell lack the ability to predict parameters other than biochemical oxygen demand (BOD) and nitrogen. Oxygen consumption is usually estimated from BOD utilization. LAGOON is a fortran program which models the biogeochemical processes characteristic of the primary cell of facultative lagoons. Model parameters can be measured from lagoons in the vicinity of a proposed lagoon or estimated from laboratory studies. The model was calibrated utilizing a subset of the Corinne Utah lagoon data then validated utilizing a subset of the Corinne Utah data.

New, G.R.

1987-01-01

7

Virtual driving and eco-simulation: VR city modeling, drive simulation, and ecological habits  

Microsoft Academic Search

This paper introduces a VR city model developed for research in driving simulation, driver behavior, and vehicle emissions. The project is a part of an interdisciplinary multi-year academic research grant at Arizona State University. First, the outline of the research is explained. The methods of VR city modeling are then introduced. The modeling process of creating road and intersection networks

Christopher J. Grasso; Michael J. McDearmon; Yoshihiro Kobayashi

2010-01-01

8

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...

9

Sensitivity of an ecological model to soil moisture simulations from two different hydrological models  

Microsoft Academic Search

Summary  Although advanced land surface schemes have been developed in the past decade, many biosphere models still use the simple\\u000a bucket model, partly due to its efficiency when it is coupled with an CGCM model. In this paper, we use a sophisticated land\\u000a surface model, the Simulator for Hydrology and Energy Exchange at the Land Surface (SHEELS), including an explicit vegetation

D. Ren; L. M. Leslie; D. J. Karoly

2008-01-01

10

The use of typed lambda calculus for comprehension and construction of simulation models in the domain of ecology  

NASA Technical Reports Server (NTRS)

We are concerned with two important issues in simulation modelling: model comprehension and model construction. Model comprehension is limited because many important choices taken during the modelling process are not documented. This makes it difficult for models to be modified or used by others. A key factor hindering model construction is the vast modelling search space which must be navigated. This is exacerbated by the fact that many modellers are unfamiliar with the terms and concepts catered to by current tools. The root of both problems is the lack of facilities for representing or reasoning about domain concepts in current simulation technology. The basis for our achievements in both of these areas is the development of a language with two distinct levels; one for representing domain information, and the other for representing the simulation model. Of equal importance, is the fact that we make formal connections between these two levels. The domain we are concerned with is ecological modelling. This language, called Elklogic, is based on the typed lambda calculus. Important features include a rich type structure, the use of various higher order functions, and semantics. This enables complex expressions to be constructed from relatively few primitives. The meaning of each expression can be determined in terms of the domain, the simulation model, or the relationship between the two. We describe a novel representation for sets and substructure, and a variety of other general concepts that are especially useful in the ecological domain. We use the type structure in a novel way: for controlling the modelling search space, rather than a proof search space. We facilitate model comprehension by representing modelling decisions that are embodied in the simulation model. We represent the simulation model separately from, but in terms of a domain mode. The explicit links between the two models constitute the modelling decisions. The semantics of Elklogic enables English text to be generated to explain the simulation model in domain terms.

Uschold, Michael

1992-01-01

11

Simulation of regionally ecological land based on a cellular automation model: a case study of Beijing, China.  

PubMed

Ecological land is like the "liver" of a city and is very useful to public health. Ecological land change is a spatially dynamic non-linear process under the interaction between natural and anthropogenic factors at different scales. In this study, by setting up natural development scenario, object orientation scenario and ecosystem priority scenario, a Cellular Automation (CA) model has been established to simulate the evolution pattern of ecological land in Beijing in the year 2020. Under the natural development scenario, most of ecological land will be replaced by construction land and crop land. But under the scenarios of object orientation and ecosystem priority, the ecological land area will increase, especially under the scenario of ecosystem priority. When considering the factors such as total area of ecological land, loss of key ecological land and spatial patterns of land use, the scenarios from priority to inferiority are ecosystem priority, object orientation and natural development, so future land management policies in Beijing should be focused on conversion of cropland to forest, wetland protection and prohibition of exploitation of natural protection zones, water source areas and forest parks to maintain the safety of the regional ecosystem. PMID:23066410

Xie, Hualin; Kung, Chih-Chun; Zhang, Yanting; Li, Xiubin

2012-08-01

12

Simulation of Regionally Ecological Land Based on a Cellular Automation Model: A Case Study of Beijing, China  

PubMed Central

Ecological land is like the “liver” of a city and is very useful to public health. Ecological land change is a spatially dynamic non-linear process under the interaction between natural and anthropogenic factors at different scales. In this study, by setting up natural development scenario, object orientation scenario and ecosystem priority scenario, a Cellular Automation (CA) model has been established to simulate the evolution pattern of ecological land in Beijing in the year 2020. Under the natural development scenario, most of ecological land will be replaced by construction land and crop land. But under the scenarios of object orientation and ecosystem priority, the ecological land area will increase, especially under the scenario of ecosystem priority. When considering the factors such as total area of ecological land, loss of key ecological land and spatial patterns of land use, the scenarios from priority to inferiority are ecosystem priority, object orientation and natural development, so future land management policies in Beijing should be focused on conversion of cropland to forest, wetland protection and prohibition of exploitation of natural protection zones, water source areas and forest parks to maintain the safety of the regional ecosystem. PMID:23066410

Xie, Hualin; Kung, Chih-Chun; Zhang, Yanting; Li, Xiubin

2012-01-01

13

Ecological Modelling 140 (2001) 18 Integrating ecology with human demography, behavior, and  

E-print Network

Ecological Modelling 140 (2001) 1­8 Integrating ecology with human demography, behavior an urgent need to integrate ecology with human demography, behavior, and socioeconomics in order; Human demography; Human behavior; Sociology; Economics; Modeling; Simulation. www

14

Modelling the Geomorphological and Ecological Dynamics of River Corridors: Developing a Simulation Tool for River Management  

NASA Astrophysics Data System (ADS)

Interest in the integrated restoration of managed river corridors has arisen in response to falling levels of riparian and floodplain biodiversity due to flood control works including channalization and flow regulation by headwater impoundments. This decline is in part, a direct response to the impact of engineering works on the geomorphological dynamics of rivers and in particular, upon rates of channel migration. Channel instability, through the processes of bank erosion, avulsion and cutoff, and within and overbank sedimentation, continuously renews the floodplain creating virgin territory for plant colonization. The varying age of alluvial surfaces, in combination with differences in topography and sediment calibre influence plant succession pathways and gives rise to a mosaic of floodplain plant communities. This geomorphological influence underpins the `intermediate disturbance hypothesis' which suggests a non-linear relationship between floodplain turnover rates and biodiversity, which is low in both highly stable and unstable rivers regimes. In the former case, diversity is limited as stable regimes promote succession towards relatively uniform stands of floodplain forest while the in the later case, extreme instability results in the sole dominance of early coloniser species. By contrast, diversity is maximized for intermediate levels of disturbance, which result in a range of habitats at varying positions along successional pathways. While conceptually satisfying, calibration and validation of this perceptual model is confounded by the differing local conditions and environmental history of individual rivers, which complicates simple empirical inter-comparisons. Prescription of the appropriate levels of disturbance necessary to optimise habitat and biological diversity therefore remains unclear and difficult to translate into practical frameworks for river management. This paper presents an alternative approach to investigate this interdependence through the development of a numerical model which captures the primary geomorphological and ecological dynamics of river systems at appropriate levels of complexity tuned to reach and decadal space and time scales. Here a prototype model is presented for braided rivers, in which a simplified flow routing procedure is used to drive predictions of sediment transport and sorting based on a cellular spatial discretization, a force-balance entrainment model and a step-length advection and grain sorting procedure. This sub-model provides the topographic and sedimentological boundary conditions for a stochastic plant succession model which simulates colonization and community development on the evolving braidplain. The model is parameterised and validated against distributed datasets from the braided River Feshie, Scotland. A Monte-Carlo based sensitivity analysis is used to explore the one-way interaction between channel migration and habitat development, with an emphasis placed on the structure of the evolving timeseries of reach-scale biodiversity indicators. Importantly however, the framework also permits full coupling of this interrelationship by modelling the influence of vegetation on bank stability so that feedback can occur to affect channel migration and floodplain turnover. Such feedback is critical in understanding the autogenic switching between channel planform types (meandering and braiding) and a new computational framework for simulating this behaviour is presented.

Brasington, J.; Richards, K.; Bithell, M.

2002-12-01

15

Linking Bayesian and Agent-Based Models to Simulate Complex Social-Ecological Systems in the Sonoran Desert  

NASA Astrophysics Data System (ADS)

Interdependencies of ecologic, hydrologic, and social systems challenge traditional approaches to natural resource management in semi-arid regions. As a complex social-ecological system, water demands in the Sonoran Desert from agricultural and urban users often conflicts with water needs for its ecologically-significant riparian corridors. To explore this system, we developed an agent-based model to simulate complex feedbacks between human decisions and environmental conditions. Cognitive mapping in conjunction with stakeholder participation produced a Bayesian model of conditional probabilities of local human decision-making processes resulting to changes in water demand. Probabilities created in the Bayesian model were incorporated into the agent-based model, so that each agent had a unique probability to make a positive decision based on its perceived environment at each point in time and space. By using a Bayesian approach, uncertainty in the human decision-making process could be incorporated. The spatially-explicit agent-based model simulated changes in depth-to-groundwater by well pumping based on an agent's water demand. Depth-to-groundwater was then used as an indicator of unique vegetation guilds within the riparian corridor. Each vegetation guild provides varying levels of ecosystem services, the changes of which, along with changes in depth-to-groundwater, feedback to influence agent behavior. Using this modeling approach allowed us to examine resilience of semi-arid riparian corridors and agent behavior under various scenarios. The insight provided by the model contributes to understanding how specific interventions may alter the complex social-ecological system in the future.

Pope, A.; Gimblett, R.

2013-12-01

16

Comparison of simulation modeling and satellite techniques for monitoring ecological processes  

NASA Technical Reports Server (NTRS)

In 1985 improvements were made in the world climatic data base for modeling and predictive mapping; in individual process models and the overall carbon-balance models; and in the interface software for mapping the simulation results. Statistical analysis of the data base was begun. In 1986 mapping was shifted to NASA-Goddard. The initial approach involving pattern comparisons was modified to a more statistical approach. A major accomplishment was the expansion and improvement of a global data base of measurements of biomass and primary production, to complement the simulation data. The main accomplishments during 1987 included: production of a master tape with all environmental and satellite data and model results for the 1600 sites; development of a complete mapping system used for the initial color maps comparing annual and monthly patterns of Normalized Difference Vegetation Index (NDVI), actual evapotranspiration, net primary productivity, gross primary productivity, and net ecosystem production; collection of more biosphere measurements for eventual improvement of the biological models; and development of some initial monthly models for primary productivity, based on satellite data.

Box, Elgene O.

1988-01-01

17

Simulated ecology-driven sympatric speciation  

NASA Astrophysics Data System (ADS)

We introduce a multilocus genetically acquired phenotype, submitted to mutations and with selective value, in an age-structured model for biological aging. This phenotype describes a single-trait effect of the environment on an individual, and we study the resulting distribution of this trait among the population. In particular, our simulations show that the appearance of a double phenotypic attractor in the ecology induces the emergence of a stable polymorphism, as observed in the Galapagos finches. In the presence of this polymorphism, the simulations generate short-term speciation, when mating preferences are also allowed to suffer mutations and acquire selective value.

Sá Martins, J. S.; Moss de Oliveira, S.; de Medeiros, G. A.

2001-08-01

18

Multi-Criteria Assessment of Ecological Process Models  

E-print Network

, model verification, model validation, multiple criteria, binary error measures, genetic algorithms, simulated evolution, evolutionary computation, individual based models, canopy competition, model revision, WHORL. #12;03/11/98 4 INTRODUCTION Complex simulation models of ecological processes are increasingly

Washington at Seattle, University of

19

Fire-BGC: A mechanistic ecological process model for simulating fire succession on coniferous forest landscapes of the northern Rocky Mountains. Forest Service research paper  

SciTech Connect

An ecological process model of vegetation dynamics mechanistically simulates long-term stand dynamics on coniferous landscapes of the Northern Rocky Mountains. This model is used to investigate and evaluate cumulative effects of various fire regimes, including prescribed burning and fire exclusion, on the vegetation and fuel complex of a simulation landscape composed of many stands. Detailed documentation of the model FIRE-BGC (a FIRE BioGeoChemical succession model) with complete discussion of all model parameters is followed with results of an application of the FIRE-BGC to a whitebark pine landscape in the Bob Marshall Wilderness Complex. Simulation results of several management scenarios are contrasted to predict the fate of whitebark pine over 200 years. Model testing reveals predictions within 10 to 30 percent of observed values.

Keane, R.E.; Morgan, P.; Running, S.W.

1996-03-01

20

Simulation analysis on the regulation of overflow ecological water consumption in arid areas  

Microsoft Academic Search

After analyzing the regulation of overflow ecological water consumption in the Canmrik ecological area of mainstream zone\\u000a of the Tarim River, in this paper a model of ecological bifurcation is developed, the dynamic overflow process of ecological\\u000a bifurcation is simulated, and the quantitative relationships between the volume of ecological water consumption and the ecological\\u000a conservation extent and overflow time are

Xi Chen; Yue Huang; Jing Qian; HaiLong Liu; XianWei Feng; Ying Liu; AnMing Bao; WeiSheng Wang

2007-01-01

21

COMMUNITY ECOLOGY Toward ecologically explicit null models of nestedness  

E-print Network

of nestedness as an ecological concept and conservation tool. Keywords Forest songbirds Á Random placement modelCOMMUNITY ECOLOGY Toward ecologically explicit null models of nestedness Jeffrey E. Moore � Robert nonrandom subsets of those at richer sites. Conventional null models used to test for statistically

Swihart, Robert K. "Rob"

22

Modeling & Simulation  

NSDL National Science Digital Library

Modeling & Simulation is a journal published by The Society for Modeling and Simulation International. The Society has made its 2004 Modeling and Simulation Resource Guide available free to download. The directory provides descriptions and contact information for the many modeling and simulation software packages currently available, as well as listings for various modeling and simulation organizations worldwide. Two guest articles describe techniques for the application of real-time simulation in simulations that are complex. Previously published articles are also posted in the online archive.

23

Testing ecological models: the meaning of validation  

Microsoft Academic Search

The ecological literature reveals considerable confusion about the meaning of validation in the context of simulation models. The confusion arises as much from semantic and philosophical considerations as from the selection of validation procedures. Validation is not a procedure for testing scientific theory or for certifying the ‘truth’ of current scientific understanding, nor is it a required activity of every

Edward J. Rykiel

1996-01-01

24

Cosmic emergy based ecological systems modelling  

NASA Astrophysics Data System (ADS)

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.

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

2010-09-01

25

Evolution and Simulation Analysis of Mine Ecological Economy System  

Microsoft Academic Search

Mine ecological carrying capability and ecological elastic capability were analysised and the dynamics model of system evolution on mine ecological economy was put forward based on mine ecological carrying capability and ecological elastic capability as state factors of mine eco-system, economic development activities intensity of mineral resources and economic development speed of mineral resources as state factors of mine economic

Sun Shun-li

2010-01-01

26

Register of Ecological Models (REM)  

NSDL National Science Digital Library

Created cooperatively by the University of Kassel and the GSF-National Research Center for Environment and Health in Germany, and maintained by Joachim Benz, this site currently contains 481 ecological models. Users can search the database by model name or subject (e.g., population dynamics, hydrology), browse a brief list of related literature, or enter information on models not currently in the database. Professionals in the life and physical sciences can find common ground at this site.

1998-01-01

27

Spatial uncertainty and ecological models  

SciTech Connect

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.

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

2004-07-01

28

Auto-calibration of a one-dimensional hydrodynamic-ecological model using a Monte Carlo approach: simulation of hypoxic events in a polymictic lake  

NASA Astrophysics Data System (ADS)

Automated calibration of complex deterministic water quality models with a large number of biogeochemical parameters can reduce time-consuming iterative simulations involving empirical judgements of model fit. We undertook auto-calibration of the one-dimensional hydrodynamic-ecological lake model DYRESM-CAEDYM, using a Monte Carlo sampling (MCS) method, in order to test the applicability of this procedure for shallow, polymictic Lake Rotorua (New Zealand). The calibration procedure involved independently minimising the root-mean-square-error (RMSE), maximizing the Pearson correlation coefficient (r) and Nash-Sutcliffe efficient coefficient (Nr) for comparisons of model state variables against measured data. An assigned number of parameter permutations was used for 10,000 simulation iterations. The 'optimal' temperature calibration produced a RMSE of 0.54 °C, Nr-value of 0.99 and r-value of 0.98 through the whole water column based on comparisons with 540 observed water temperatures collected between 13 July 2007 - 13 January 2009. The modeled bottom dissolved oxygen concentration (20.5 m below surface) was compared with 467 available observations. The calculated RMSE of the simulations compared with the measurements was 1.78 mg L-1, the Nr-value was 0.75 and the r-value was 0.87. The autocalibrated model was further tested for an independent data set by simulating bottom-water hypoxia events for the period 15 January 2009 to 8 June 2011 (875 days). This verification produced an accurate simulation of five hypoxic events corresponding to DO < 2 mg L-1 during summer of 2009-2011. The RMSE was 2.07 mg L-1, Nr-value 0.62 and r-value of 0.81, based on the available data set of 738 days. The auto-calibration software of DYRESM-CAEDYM developed here is substantially less time-consuming and more efficient in parameter optimisation than traditional manual calibration which has been the standard tool practiced for similar complex water quality models.

Luo, L.

2011-12-01

29

CollageMachine: Model of ``Interface Ecology''  

E-print Network

CollageMachine: Model of ``Interface Ecology'' By Andruid Kerne dissertation submitted partial addresses browsing creatively, been co­developed with the metadisciplinary framework interface ecology, in addition inside them, open process without definite bounds. a metadiscipline, interface ecology brings

Mohri, Mehryar

30

Spatiotemporal modelling of ecological and evolutionary problems  

E-print Network

Spatiotemporal modelling of ecological and evolutionary problems DSc. dissertation Czárán Tamás MTA;DSc Dissertation:......................................................................................................................145 #12;DSc Dissertation

Czárán, Tamás

31

Ecological economic modeling and valuation of ecosystems  

Microsoft Academic Search

We are attempting to integrate ecological and economic modeling and analysis in order to improve our understanding of regional systems, assess potential future impacts of various land-use, development, and agricultural policy options, and to better assess the value of ecological systems. Starting with an existing spatially articulated ecosystem model of the Patuxent River drainage basin in Maryland, we are adding

N. Bockstael; R. Costanza; I. Strand; W. Boynton; K. Bell; L. Wainger

1995-01-01

32

Role of Ecological Modeling in Risk Assessment  

Microsoft Academic Search

Ecological models are useful tools for evaluating the ecological significance of observed or predicted effects of toxic chemicals on individual organisms. Current risk estimation approaches using hazard quotients for individual-level endpoints have limited utility for assessing risks at the population, ecosystem, and landscape levels, which are the most relevant indicators for environmental management. In this paper, we define different types

Robert A. Pastorok; Resit Akçakaya; Helen Regan; Scott Ferson; Steven M. Bartell

2003-01-01

33

Strategies for landscape ecology: An application using cellular automata models  

Microsoft Academic Search

The countervailing cellular automata (CVCA) is a loose coupled program designed to work in conjunction with SLEUTH (an urban cellular automata simulation model). CVCA operationalises a set of landscape ecological strategies for urban planning. CVCA first assesses a landscape against a set of landscape metrics. It then evaluates the proposed urban cells from SLEUTH against the metrics and allocates future

Elisabete A. Silva; Jack Ahern; Jack Wileden

2008-01-01

34

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

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.

S.P. Rupp

2005-10-01

35

Toward an Ecological Evaluation Model.  

ERIC Educational Resources Information Center

The authors suggest that the aura of authority traditionally placed on educational research and evaluation has been based on an outdated understanding of the scientific enterprise. They outline an alternative view of science which is more ecological and provides more scope and power for evaluating educational programs. They propose a new framework…

Parker, Jackson; Patterson, Jerry L.

1979-01-01

36

Spatial Uncertainty Analysis of Ecological Models  

SciTech Connect

The authors evaluated the sensitivity of a habitat model and a source-sink population model to spatial uncertainty in landscapes with different statistical properties and for hypothetical species with different habitat requirements. Sequential indicator simulation generated alternative landscapes from a source map. Their results showed that spatial uncertainty was highest for landscapes in which suitable habitat was rare and spatially uncorrelated. Although, they were able to exert some control over the degree of spatial uncertainty by varying the sampling density drawn from the source map, intrinsic spatial properties (i.e., average frequency and degree of spatial autocorrelation) played a dominant role in determining variation among realized maps. To evaluate the ecological significance of landscape variation, they compared the variation in predictions from a simple habitat model to variation among landscapes for three species types. Spatial uncertainty in predictions of the amount of source habitat depended on both the spatial life history characteristics of the species and the statistical attributes of the synthetic landscapes. Species differences were greatest when the landscape contained a high proportion of suitable habitat. The predicted amount of source habitat was greater for edge-dependent (interior) species in landscapes with spatially uncorrelated(correlated) suitable habitat. A source-sink model demonstrated that, although variation among landscapes resulted in relatively little variation in overall population growth rate, this spatial uncertainty was sufficient in some situations, to produce qualitatively different predictions about population viability (i.e., population decline vs. increase).

Jager, H.I.; Ashwood, T.L.; Jackson, B.L.; King, A.W.

2000-09-02

37

ECOMOD — An ecological approach to radioecological modelling  

Microsoft Academic Search

A unified methodology is proposed to simulate the dynamic processes of radionuclide migration in aquatic food chains in parallel with their stable analogue elements. The distinguishing feature of the unified radioecological\\/ecological approach is the description of radionuclide migration along with dynamic equations for the ecosystem. The ability of the methodology to predict the results of radioecological experiments is demonstrated by

Tatiana G. Sazykina

2000-01-01

38

Individual-based models in ecology after four decades  

PubMed Central

Individual-based models simulate populations and communities by following individuals and their properties. They have been used in ecology for more than four decades, with their use and ubiquity in ecology growing rapidly in the last two decades. Individual-based models have been used for many applied or “pragmatic” issues, such as informing the protection and management of particular populations in specific locations, but their use in addressing theoretical questions has also grown rapidly, recently helping us to understand how the sets of traits of individual organisms influence the assembly of communities and food webs. Individual-based models will play an increasingly important role in questions posed by complex ecological systems. PMID:24991416

Grimm, Volker

2014-01-01

39

Simulating evolutionary responses of an introgressed insect resistance trait for ecological effect assessment of transgene flow: a model for supporting informed decision-making in environmental risk assessment  

PubMed Central

Predicting outcomes of transgene flow from arable crops requires a system perspective that considers ecological and evolutionary processes within a landscape context. In Europe, the arable weed Raphanus raphanistrum is a potential hybridization partner of oilseed rape, and the two species are ecologically linked through the common herbivores Meligethes spp. Observations in Switzerland show that high densities of Meligethes beetles maintained by oilseed rape crops can lead to considerable damage on R. raphanistrum. We asked how increased insect resistance in R. raphanistrum – as might be acquired through introgression from transgenic oilseed rape – would affect seed production under natural herbivore pressure. In simulation experiments, plants protected against Meligethes beetles produced about twice as many seeds as unprotected plants. All stages in the development of reproductive structures from buds to pods were negatively affected by the herbivore, with the transition from buds to flowers being the most vulnerable. We conclude that resistance to Meligethes beetles could confer a considerable selective advantage upon R. raphanistrum in regions where oilseed rape is widely grown. PMID:23467842

Meier, Matthias S; Trtikova, Miluse; Suter, Matthias; Edwards, Peter J; Hilbeck, Angelika

2013-01-01

40

Using Student Generated Qualitative Ecological Models  

NSDL National Science Digital Library

As simplifications of real system, models can be used by students to improve their understanding of an ecosystem and to make predictions about what will happen after a disturbance or other change to the ecosystem. This activity guides students through the development of quantitative ecological models. Students use a model to explore how ecosystems work and to predict how disturbance can affect ecosystem function.

Dresner, Marion

2010-02-16

41

Simulating the effects of fire and climate change on northern Rocky Mountain landscapes using the ecological process model FIRE-BGC  

SciTech Connect

A mechanistic successional model, FIRE-BGC (a FIRE BioGeoChemical succession model), has been developed to investigate the role of fire and climate on long-term landscape dynamics in northern Rocky Mountain coniferous forests. This FIRE-BGC application explicitly simulates fire behavior and effects on landscape characteristics. Predictions of evapotranspiration are contrasted with and without fire over 200 years of simulation for the McDonald Drainage, Glacier National Park under current climate conditions are provided as an example of the potential of FIRE-BGC.

Keane, R.E.; Ryan, K. [Intermountain Fire Sciences Lab., Missoula, MT (United States); Running, S.W. [Univ. of Montana, Missoula, MT (United States). School of Forestry

1995-12-31

42

OVERVIEW OF CLIMATE INFORMATION NEEDS FOR ECOLOGICAL EFFECTS MODELS  

EPA Science Inventory

Atmospheric scientists engaged in climate change research require a basic understanding of how ecological effects models incorporate climate. This report provides an overview of existing ecological models that might be used to model climate change effects on vegetation. ome agric...

43

QUANTITATIVE ECOLOGY Modeling Colonization of Overwintered Immigrant  

E-print Network

QUANTITATIVE ECOLOGY Modeling Colonization of Overwintered Immigrant Leptinotarsa decemlineata of immigration for individual overwintered adults. Distance was measured to the nearest Ã?eld edge or to the Ã?eld deployment of control measures against immigrating beetles and applicability for spatially explicit

44

Crisis in Context Theory: An Ecological Model  

ERIC Educational Resources Information Center

This article outlines a theory for understanding the impact of a crisis on individuals and organizations. Crisis in context theory (CCT) is grounded in an ecological model and based on literature in the field of crisis intervention and on personal experiences of the authors. A graphic representation denotes key components and premises of CCT,…

Myer, Rick A.; Moore, Holly B.

2006-01-01

45

Social Ecological Model Analysis for ICT Integration  

ERIC Educational Resources Information Center

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…

Zagami, Jason

2013-01-01

46

Modelling macroevolutionary patterns: An ecological perspective  

NASA Astrophysics Data System (ADS)

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.

Solé, R. V.

47

Ecological Modelling xxx (2005) xxxxxx Modelling carbon and water cycles in a beech forest  

E-print Network

Ecological Modelling xxx (2005) xxx­xxx Modelling carbon and water cycles in a beech forest Part I, stems, branches, coarse and fine roots, evapotranspira- tion, soil heterotrophic respiration, water on simulated NEE. Finally 17 parameters, linked to photosynthesis, vegetative respiration and soil water

Boyer, Edmond

48

An ecological process model of systems change.  

PubMed

In June 2007 the American Journal of Community Psychology published a special issue focused on theories, methods and interventions for systems change which included calls from the editors and authors for theoretical advancement in this field. We propose a conceptual model of systems change that integrates familiar and fundamental community psychology principles (succession, interdependence, cycling of resources, adaptation) and accentuates a process orientation. To situate our framework we offer a definition of systems change and a brief review of the ecological perspective and principles. The Ecological Process Model of Systems Change is depicted, described and applied to a case example of policy driven systems level change in publicly funded social programs. We conclude by identifying salient implications for thinking and action which flow from the Model. PMID:21203829

Peirson, Leslea J; Boydell, Katherine M; Ferguson, H Bruce; Ferris, Lorraine E

2011-06-01

49

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

E-print Network

B.V. All rights reserved. Keywords: Landscape model; Animal movement; Dispersal behavior modellingEcological Modelling 190 (2006) 159­170 Animal dispersal modelling: Handling landscape features and related animal choices S´everine Vuilleumier, Richard Metzger Institute of Environmental Science

Alvarez, Nadir

50

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

51

ECOLECON: An ECOLogical-ECONomic model for species conservation in complex forest landscapes  

Microsoft Academic Search

Liu, J., 1993. ECOLECON: An ECOLogical-ECONomic model for species conscrvation in complex forcst landscapes. Ecol. Modelling, 70: 63-87, An ECOLogical-ECONomic model (ECOLECON) has bccn developed to simulate animal population dynamics and economic rcvenucs in rcsponsc to diffcrcnt forest land- scape structurc and timber management scenarios. ECOLECON is a spatially-explicit, individual-based, and object-orientcd program. It is codcd in Borland C +

Jianguo Liu

1993-01-01

52

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

PubMed Central

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

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

2014-01-01

53

Evaluation of model predictions of the ecological effects of 4-nonylphenol -- before and after model refinement  

SciTech Connect

The Littoral Ecosystem Risk Assessment Model (LERAM) is a bioenergetic ecosystem effects model. It links single species toxicity data to a bioenergetic model of the trophic structure of an ecosystem in order to simulate community and ecosystem level effects of chemical stressors. LERAM was used in 1992 to simulate the ecological effects of diflubenzuron. When compared to the results from a littoral enclosure study, the model exaggerated the cascading of effects through the trophic levels of the littoral ecosystem. It was hypothesized that this could be corrected by making minor changes in the representation of the littoral food web. Two refinements of the model were therefore performed: (1) the plankton and macroinvertebrate model populations [eg., predatory Copepoda, herbivorous Insecta, green phytoplankton, etc.] were changed to better represent the habitat and feeding preferences of the endemic taxa; and (2) the method for modeling the microbial degradation of detritus (and the resulting nutrient remineralization) was changed from simulating bacterial populations to simulating bacterial function. Model predictions of the ecological effects of 4-nonylphenol were made before and after these refinements. Both sets of predictions were then compared to the results from a littoral enclosure study of the ecological effects of 4-nonylphenol. The changes in the LERAM predictions were then used to determine the success of the refinements, to guide. future research, and to further define LERAM`s domain of application.

Hanratty, M.P.; Liber, K. [Univ. of Wisconsin, Superior, WI (United States)

1994-12-31

54

An Ecological Model for Premature Infant Feeding  

PubMed Central

Premature infants are at increased risk for poor health, feeding difficulties, and impaired mother-infant interaction leading to developmental delay. Social-environmental risks, such as poverty or minority status, compound these biologic risks, placing premature infants in double jeopardy. Guided by an ecological model, the Hospital-Home Transition: Optimizing Prematures’ Environment (H-HOPE) intervention combines the Auditory, Tactile, Visual, and Vestibular intervention with participatory guidance provided by a nurse and community advocate to address the impact of multiple risk factors on premature infants’ development. PMID:19614884

White-Traut, Rosemary; Norr, Kathleen

2013-01-01

55

An ecological model for premature infant feeding.  

PubMed

Premature infants are at increased risk for poor health, feeding difficulties, and impaired mother-infant interaction, leading to developmental delay. Social-environmental risks, such as poverty or minority status, compound these biological risks, placing premature infants in double jeopardy. Guided by an ecological model, the Hospital-Home Transition: Optimizing Prematures' Environment intervention combines the auditory, tactile, visual, and vestibular intervention with participatory guidance provided by a nurse and community advocate to address the impact of multiple risk factors on premature infants' development. PMID:19614884

White-Traut, Rosemary; Norr, Kathleen

2009-01-01

56

A physiologically-based model of a self-motivated hare in relation to its ecology  

Microsoft Academic Search

The use of individually-based, detail-rich, simulation models for the study of the behavioral ecology of wildlife is expanding for their ability to link evolutionary processes operating at the individual level (e.g. optimal foraging) to ecological and demographic processes usually described at the population level. Within this modelling framework, we tested the possibility of using artificial intelligence (AI) methods and object-oriented

M. Rizzotto; S. Focardi

1997-01-01

57

Big questions, small worlds: microbial model systems in ecology  

Microsoft Academic Search

Although many biologists have embraced microbial model systems as tools to address genetic and physiological questions, the explicit use of microbial communities as model systems in ecology has traditionally been more restricted. Here, we highlight recent studies that use laboratory-based microbial model systems to address ecological questions. Such studies have significantly advanced our understanding of processes that have proven difficult

Christine M. Jessup; Rees Kassen; Samantha E. Forde; Ben Kerr; Angus Buckling; Paul B. Rainey; Brendan J. M. Bohannan

2004-01-01

58

Aviation Safety Simulation Model  

NASA Technical Reports Server (NTRS)

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.

Houser, Scott; Yackovetsky, Robert (Technical Monitor)

2001-01-01

59

Validation of simulation models  

Microsoft Academic Search

This is a tutorial paper on validation of simulation models. Included in this tutorial are what is meant by validation, the problem dependent characteristics of simulation model validation, descriptions of the various validation techniques and their use and a discussion on the statistics used in validation techniques (but not the detailed statistical tests themselves).

Robert G. Sargent

1979-01-01

60

Ecological Modeling: A Tool for the Urban Educator.  

ERIC Educational Resources Information Center

Ecological modeling is a holistic systems level approach to situational analysis which can be used in planning activities for lifelong learning in an urban setting. It is the purpose of this essay to present a discussion of ecological modeling in its pure or conceptual sense and concomitantly to translate this analysis into an effective and…

Spikes, Frank

61

SFRSF: Landscape Synthesis and Ecological Modeling  

NSDL National Science Digital Library

This South Florida Restoration Science Forum (SFRSF) site explores how to understand, describe, and predict ecological changes at the landscape and regional levels. Issues discussed include the effects of landscape hydrology on specific animal populations, predicting ecological responses to landscape management, understanding changes in the landscape by studying vegetation patterns, and the Cape Sable Seaside Sparrow's importance to understanding ecological changes. Links are provided for further information.

62

Coupled physical-ecological modelling in the central part of Jiaozhou Bay II. Coupled with an ecological model  

NASA Astrophysics Data System (ADS)

Sharples' 1-D physical model employing tide-wind driven turbulence closure and surface heating-cooling physics, was coupled with an ecological model with 9-biochemical components: phytoplankton, zooplankton, shellfish, autotrophic and heterotrophic bacterioplankton, dissolved organic carbon (DOC), suspended detritus and sinking particles to simulate the annual evolution of ecosystem in the central part of Jiaozhou Bay. The coupled modeling results showed that the phytoplankton shading effect could reduce seawater temperature by 2°C, so that photosynthesis efficiency should be less than 8%; that the loss of phytoplankton by zooplankton grazing in winter tended to be compensated by phytoplankton advection and diffusion from the outside of the Bay; that the incident irradiance intensity could be the most important factor for phytoplankton growth rate; and that it was the bacterial secondary production that maintained the maximum zooplankton biomass in winter usually observed in the 1990s, indicating that the microbial food loop was extremely important for ecosystem study of Jiaozhou Bay.

Cui, Mao-Chang; Zhu, Hai

2001-03-01

63

Cognitive Modeling for Agent-Based Simulation of Child Maltreatment  

NASA Astrophysics Data System (ADS)

This paper extends previous work to develop cognitive modeling for agent-based simulation of child maltreatment (CM). The developed model is inspired from parental efficacy, parenting stress, and the theory of planned behavior. It provides an explanatory, process-oriented model of CM and incorporates causality relationship and feedback loops from different factors in the social ecology in order for simulating the dynamics of CM. We describe the model and present simulation results to demonstrate the features of this model.

Hu, Xiaolin; Puddy, Richard

64

A complementary ecological model of the coordinated school health program.  

PubMed

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

Lohrmann, David K

2008-01-01

65

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

E-print Network

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

Hodgson, Michael E.

66

Stochastic Downscaling for Hydrodynamic and Ecological Modeling of Lakes  

NASA Astrophysics Data System (ADS)

Weather generators are of interest in climate impact studies, because they allow different modi operandi: (1) More realizations of the past, (2) possible futures as defined by the modeler and (3) possible futures according to the combination of greenhouse gas emission scenarios and their Global Circulation Model (GCM) consequences. Climate modeling has huge inherently unquantifiable uncertainties, yet the results present themselves as single point values without any measure of uncertainty. Given this reduction of risk-relevant information, stochastic downscaling offers itself as a tool to recover the variability present in local measurements. One should bear in mind that the lake models that are fed with downscaling results are themselves deterministic and single runs may prove to be misleading. Especially population dynamics simulated by ecological models are sensitive to very particular events in the input data. A way to handle this sensitivity is to perform Monte Carlo studies with varying meteorological driving forces using a weather generator. For these studies, the Vector-Autoregressive Weather generator (VG), which was first presented at the EGU 2011, was developed further. VG generates daily air temperature, humidity, long- and shortwave radiance and wind. Wind and shortwave radiation is subsequently disaggregated to hourly values, because their short term variability has proven important for the application. Changes relative to the long-term values are modeled as disturbances that act during the autoregressive generation of the synthetic time series. The method preserves the dependence structure between the variables, as changes in the disturbed variable, say temperature, are propagated to the other variables. The approach is flexible because the disturbances can be chosen freely. Changes in mean can be represented as constant disturbance, changes in variability as episodes of certain length and amplitude. The disturbances can also be extracted from GCMs with the help of QQ-downscaled time series. Results of water-quality and ecological modeling using data from VG is contributed by Marieke Anna Frassl under the title "Simulating the effect of meteorological variability on a lake ecosystem". Maria Magdalena Eder contributes three dimensional hydrodynamic lake simulations using VG data in a poster entitled "Advances in estimating the climate sensibility of a large lake using scenario simulations". Both posters can be found in the Session "Lakes and Inland Seas" (HS10.1).

Schlabing, D.; Eder, M.; Frassl, M.; Rinke, K.; Bárdossy, A.

2012-04-01

67

Models and Simulations  

NSDL National Science Digital Library

Scientists use models and simulations to help them visualize, explain, and make predictions and hypotheses about the structures, properties, and behaviors of phenomena (e.g., objects, materials, processes, systems). The extremely small size and complexity

Krajcik, Joseph S.; Sutherland, Leeann M.; Stevens, Shawn Y.

2009-10-14

68

Theory Modeling and Simulation  

SciTech Connect

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.

Shlachter, Jack [Los Alamos National Laboratory

2012-08-23

69

A Conceptual Framework for Evaluating the Domains of Applicability of Ecological Models and its Implementation in the Ecological Production Function Library - International Society for Ecological Modelling Conference  

EPA Science Inventory

The use of computational ecological models to inform environmental management and policy has proliferated in the past 25 years. These models have become essential tools as linkages and feedbacks between human actions and ecological responses can be complex, and as funds for sampl...

70

Hydrodynamic and Ecological Assessment of Nearshore Restoration: A Modeling Study  

SciTech Connect

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.

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

2010-04-10

71

Controlled Ecological Life Support System (CELSS) modeling  

NASA Technical Reports Server (NTRS)

Attention is given to CELSS, a critical technology for the Space Exploration Initiative. OCAM (object-oriented CELSS analysis and modeling) models carbon, hydrogen, and oxygen recycling. Multiple crops and plant types can be simulated. Resource recovery options from inedible biomass include leaching, enzyme treatment, aerobic digestion, and mushroom and fish growth. The benefit of using many small crops overlapping in time, instead of a single large crop, is demonstrated. Unanticipated results include startup transients which reduce the benefit of multiple small crops. The relative contributions of mass, energy, and manpower to system cost are analyzed in order to determine appropriate research directions.

Drysdale, Alan; Thomas, Mark; Fresa, Mark; Wheeler, Ray

1992-01-01

72

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...

73

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...

74

Documentation of the Ecological Risk Assessment Computer Model ECORSK.5  

SciTech Connect

The FORTRAN77 ecological risk computer model--ECORSK.5--has been used to estimate the potential toxicity of surficial deposits of radioactive and non-radioactive contaminants to several threatened and endangered (T and E) species at the Los Alamos National Laboratory (LANL). These analyses to date include preliminary toxicity estimates for the Mexican spotted owl, the American peregrine falcon, the bald eagle, and the southwestern willow flycatcher. This work has been performed as required for the Record of Decision for the construction of the Dual Axis Radiographic Hydrodynamic Test (DARHT) Facility at LANL as part of the Environmental Impact Statement. The model is dependent on the use of the geographic information system and associated software--ARC/INFO--and has been used in conjunction with LANL's Facility for Information Management and Display (FIMAD) contaminant database. The integration of FIMAD data and ARC/INFO using ECORSK.5 allows the generation of spatial information from a gridded area of potential exposure called an Ecological Exposure Unit. ECORSK.5 was used to simulate exposures using a modified Environmental Protection Agency Quotient Method. The model can handle a large number of contaminants within the home range of T and E species. This integration results in the production of hazard indices which, when compared to risk evaluation criteria, estimate the potential for impact from consumption of contaminants in food and ingestion of soil. The assessment is considered a Tier-2 type of analysis. This report summarizes and documents the ECORSK.5 code, the mathematical models used in the development of ECORSK.5, and the input and other requirements for its operation. Other auxiliary FORTRAN 77 codes used for processing and graphing output from ECORSK.5 are also discussed. The reader may refer to reports cited in the introduction to obtain greater detail on past applications of ECORSK.5 and assumptions used in deriving model parameters.

Anthony F. Gallegos; Gilbert J. Gonzales

1999-06-01

75

An ecological risk assessment paradigm using the Spatially Integrated model for Phosphorus Loading and Erosion (SIMPLE)  

Microsoft Academic Search

Ecological risk assessments provide a probabilitistic approach to analyzing and predicting ecosystem responses to stress. We are evaluating the relationship between nonpoint source (NPS) phosphorus loading and the trophic status of the aquatic ecosystem. We are using SIMPLE (the Spatially Integrated Model for Phosphorus Loading and Erosion) to identify probable phosphorus sources in a watershed, simulate the phosphorus loading to

M. D. Matlock; D. E. Storm; J. G. Sabbagh; C. T. Haan; M. D. Smolen; S. L. Burks

1994-01-01

76

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

E-print Network

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 airÃ?ow Ã?eld and insect

Geerts, Bart

77

Ecological Modelling 134 (2000) 283297 Effects of leaf area profiles and canopy stratification on  

E-print Network

We investigated the effects of the shape of leaf area profiles and the number of canopy layersEcological Modelling 134 (2000) 283­297 Effects of leaf area profiles and canopy stratification leaf area in the vertical direction, how does the shape of the leaf area profile affect simulation

Wu, Jianguo "Jingle"

78

Integrating fundamental concepts of ecology, biogeography, and sampling into effective ecological niche modeling and species distribution modeling  

E-print Network

of the accessible area in ecological niche modeling and species distribution modeling. Ecological Modelling 222:1810?1819. Beale CM, Lennon JJ, Gimona A. 2008. Opening the climate envelope reveals no macroscale associations with climate in European birds... versus conservatism: Quantitative approaches to niche evolution. Evolution 62:2868?2883. Wiley EO. 1981. The Theory and Practice of Phylogenetic Systematics. 1st edition. New York: John Wiley & Sons. Figure 1. Summary of representation...

Peterson, A. Townsend; Soberó n, Jorge

2012-10-30

79

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...

80

Comparison of modeled and measured tissue concentrations for ecological receptors  

Microsoft Academic Search

Measured soil concentrations are often used as input in ecological uptake models to estimate the concentrations of chemicals in various organisms. In this study, modeled and measured plant and animal concentrations were compared to evaluate the validity of various uptake modeling approaches for different groups of chemicals. The models used measured soil concentration data collected during a remedial investigation at

William R. Alsop; Elizabeth T. Hawkins; Mark E. Stelljes; William Collins

1996-01-01

81

Modelling Externalities between Ecological and Economic Systems  

Microsoft Academic Search

Environmental sustainability issues have in recent years received much attention from the side of environmental scientists and economists. There is a broad recognition on the relevance of external effects in open and interacting spatial systems. It would be helpful if ecological economic research would deploy an integrated analytical framework for investigation the complex nature of such multi-disciplinary issues. This paper

Shunli Wang; Peter Nijkamp; Erik Verhoef

2001-01-01

82

Space shuttle simulation model  

NASA Technical Reports Server (NTRS)

The effects of atmospheric turbulence in both horizontal and near horizontal flight, during the return of the space shuttle, are important for determining design, control, and 'pilot-in-the-loop' effects. A nonrecursive model (based on von Karman spectra) for atmospheric turbulence along the flight path of the shuttle orbiter was developed which provides for simulation of instantaneous vertical and horizontal gusts at the vehicle center-of-gravity, and also for simulation of instantaneous gust gradients. Based on this model, the time series for both gusts and gust gradients were generated and stored on a series of magnetic tapes which are entitled shuttle simulation turbulence tapes (SSTT). The time series are designed to represent atmospheric turbulence from ground level to an altitude of 10,000 meters. The turbulence generation procedure is described as well as the results of validating the simulated turbulence. Conclusions and recommendations are presented and references cited. The tabulated one dimensional von Karman spectra and the results of spectral and statistical analyses of the SSTT are contained in the appendix.

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

1980-01-01

83

Diffusion Approximations for Ecological Models P.K. Pollett  

E-print Network

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

Pollett, Phil

84

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...

85

Meeting in Korea: 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...

86

SALSA: a simulation tool to assess ecological sustainability of agricultural production.  

PubMed

In order to assess the ecological sustainability of agricultural production systems, there is a need for effective tools. We describe an environmental systems analysis tool called SALSA (Systems Ana/ysis for Sustainable Agriculture). It consists of substance/material flow models in which the simulation results are interpreted with life-cycle assessment methodology. The application of SALSA is demonstrated in a case study in which three different ways of producing pigs are compared with respect to energy input and the environmental impacts of global warming, eutrophication, and acidification. The scenario that combined a low-protein diet without soy meal with an improved manure-management technique with low nitrogen losses was the best for all impact categories studied. The strength of the SALSA models was their capacity to capture consequences of management options that had an influence on several processes on a farm, which enabled the type of complex studies we describe. PMID:16092274

Eriksson, Ingrid Strid; Elmquist, Helena; Nybrant, Thomas

2005-06-01

87

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

ERIC Educational Resources Information Center

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…

Li, Weidong; Rukavina, Paul

2012-01-01

88

Using a social-ecological model to examine obesity interventions  

Microsoft Academic Search

The Nutrition and Physical Activity Program to Prevent Obesity and Other Chronic Diseases at the Centers for Disease Control and Prevention employs a five-level Social-Ecological Model (SEM) to address and understand the issues of overweight and obesity (Hamre et al., 2006). The model suggests that there are multiple levels of influence, and that effective prevention and reduction programs should address

Susan Lee Brown

2011-01-01

89

Turing Machine as an ecological model for Task Analysis  

E-print Network

1 Turing Machine as an ecological model for Task Analysis Thierry Morineau, Emmanuel Frénod model is based on the Turing Machine formalism and takes into account the variety of situations that can opening a door. Keywords: Cognitive work analysis, task analysis, Turing machine, affordance #12;3 1

Frénod, Emmanuel

90

Ecology.  

ERIC Educational Resources Information Center

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…

National Audubon Society, New York, NY.

91

Comparison of a Landsat-based logistic regression model and socioeconomic simulation model of deforestation in the Amazon  

Microsoft Academic Search

Modeling deforestation has become increasingly important in analyzing the effects of land-cover change on ecosystems. A simulation model based on socioeconomic variables was developed and applied to a study area in Central Rondonia, Brazil over a 20 year time period. The simulation model integrates three submodels of settlement diffusion, land-use change, and ecological change and simulates the effects of colonization

Robert C. Frohn

2001-01-01

92

Modeling the ecology of symbiont-mediated protection against parasites.  

PubMed

There is increasing evidence that many maternally transmitted symbionts protect their hosts against parasites, thus ensuring their own persistence. Despite the protection they provide, such symbionts are typically found in only a fraction of the host population. This suggests that symbiont-conferred resistance is costly or that the maternal inheritance of symbionts is not perfect. To investigate these hypotheses and other properties of this complex ecological system, we develop a mathematical model based on the example of bacterial endosymbionts that protect aphids against parasitoid wasps. Simulations show that in the absence of more complex effects, a very fine balance between the costs of harboring symbionts and the strength of protection they provide is required to maintain coexistence of protected and unprotected hosts. These constraints are significantly relaxed and coexistence becomes a common outcome if deployment of symbiont-provided defenses upon a parasite attack entails an additional (induced) cost. Transmission rates of symbionts also affect coexistence, which is more frequently observed under high (but not perfect) fidelity of vertical transfer and low rates of horizontal transfer. Finally, we show that the prevalence of defensive symbionts has a strong influence on the population dynamics of hosts and parasites: population sizes are stable if and only if protected hosts dominate. PMID:22504542

Kwiatkowski, Marek; Vorburger, Christoph

2012-05-01

93

Nonlinear Statistical Modeling and Model Discovery for Ecological Data  

NASA Astrophysics Data System (ADS)

The search for dynamical models (dynamical inference) underlying time-varying phenomena is of fundamental importance for understanding and controlling complex systems in science and technology. Often, however, only part of the system's dynamics can be measured and the state of the dynamical system remains invisible (or hidden). Furthermore, the measurements are usually corrupted by noise and the dynamics is complicated by the interplay of nonlinearity and random perturbations. The problem of dynamical inference in these general settings is challenging researchers for decades. We demonstrate here a path-integral approach to this problem, in which measured data act effectively as a control force driving algorithm towards the most probable solution. The approach is semi-analytical; consequently, the resulting algorithm does not require an extensive global search for the model parameters, provides optimal compensation for the effects of dynamical noise, and is robust for a broad range of dynamical models [1,2]. The strengths of the algorithm are illustrated by inferring the parameters of the stochastic Lorenz system and comparing the results with those of earlier research. The efficiency of the algorithm is further demonstrated by solving an intensively studied problem from the population dynamics of predator-prey system [3] where the prey populations may be observed while the number of predators is difficult or impossible to estimate. We emphasize that the predator-prey dynamics is fully nonlinear, perturbed stochastically by environmental factors and is not known beforehand. We apply our approach to recover both the unknown dynamics of predators and model parameters (including parameters that are traditionally very difficult to estimate) directly from measurements of the prey dynamics The presented method can be further extended to encompass cases of colored noise and specially distributed systems. . It is hoped that techniques such as developed here may be very useful in the future for inferring important ecological variables from limited observational data, as well as in many other fields where similar practical problems are faced. In particular, it can be applied to the inference of a climate forcing mechanisms from reconstructed from the measurements of carbon dioxide in ocean sediment [4]. [1] V. N. Smelyanskiy, D. G. Luchinsky, A. Stefanovska, P. V. E. McClintock, Physical Review Letters, 94, 098101 (2005). [2] V. N. Smelyanskiy, D. G. Luchinsky, D. A. Timucin, A. Bandrivskyy, Physical Review E, 72, 026202 (2005). [3] I. Hanski, H. Henttonen, E. Korpimanaki, L. Oksanen, P. Turchin, Ecology 82, 1505 (2001). [4] S. Rahmstorf, Nature 419, 207 (2002)

Luchinsky, D. G.; Smelyanskiy, V. N.; Timucin, D. A.; Millonas, M. M.

2005-12-01

94

Model organisms retain an "ecological memory" of complex ecologically relevant environmental variation.  

PubMed

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

Beer, Karlyn D; Wurtmann, Elisabeth J; Pinel, Nicolás; Baliga, Nitin S

2014-03-01

95

A New Approach to Ecological Risk Assessment: Simulating Effects of Global Warming on Complex Ecological Networks  

NASA Astrophysics Data System (ADS)

The field of Ecological Risk Assessment (ERA) has been under development since the 1970s. Early ERA borrowed basic concepts from human health risk assessment (HRA) methodology [NAS 1983]. However, because of the nature of an ecosystem, there is a fundamental difference between HRA and ERA. In an HRA, the only receptor is a single human being and the concerned endpoints are always associated with human health issues, such as the risk of cancer. In ERA, however, entire populations, communities and ecosystems are at risk, and ERA must rigorously assess these more complex and larger scaled concerns. Many investigators have attempted to develop a new paradigm for ERA that can deal with this intrinsic distinction. Currently, a six-step framework is now widely used by the U.S. EPA and its contractors. This new paradigm is characterized by: (1) receptor identification, (2) hazard identification, (3) endpoint identification, (4) exposure assessment, (5) doseresponse assessment and (6) risk characterization [Lipton et al. 1993, Suter 1993]. The six-step framework identifies receptors at risk, possible hazards related to certain receptors, and chooses appropriate assessment and measurement endpoints [Suter 1990]. While the additional receptor and endpoint identifications improve on the traditional framework, single-species laboratory toxicity tests typically estimate ecological responses simply by predicting an environmental concentration associated with a certain stressor divided by the no-observed effect concentration (NOEC) for that stressor. This "Hazard Quotient" (HQ) approach ignores interactions between species that are critical to the functioning of communities and ecosystems.

Zhou, Yun; Brose, Ulrich; Kastenberg, William; Martinez, Neo D.

96

Author's personal copy Ecological Modelling 243 (2012) 1832  

E-print Network

caribou (Rangifer tarandus) are classified as threatened in Canada, and the Little Smoky herd in west. Introduction Woodland caribou (Rangifer tarandus caribou) in Alberta are cur- rently designated as threatened behavioral­ecological strategies in pattern-oriented modeling of caribou habitat use in a highly

Hebblewhite, Mark

97

Trade in an Ecological-economic Integrated Model  

Microsoft Academic Search

This paper incorporates the concept of ecological pyramid into the John's specific factor model of trade to examine comparative advantages, gains from trade, terms of trade, and income distributional effects of trade in the presence of non-market ecosystem services. Our results show that the market price undervalues the opportunity cost of land-intensive goods. The terms of trade, pattern of trade,

Amy R. Hwang

2009-01-01

98

Back-end Science Model Integration for Ecological Risk Assessment  

EPA Science Inventory

The U.S. Environmental Protection Agency (USEPA) relies on a number of ecological risk assessment models that have been developed over 30-plus years of regulating pesticide exposure and risks under Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Endangered Spe...

99

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...

100

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

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

101

Inferential consequences of modeling rather than measuring snow accumulation in studies of animal ecology  

USGS Publications Warehouse

Abstract. It is increasingly common for studies of animal ecology to use model-based predictions of environmental variables as explanatory or predictor variables, even though model prediction uncertainty is typically unknown. To demonstrate the potential for misleading inferences when model predictions with error are used in place of direct measurements, we compared snow water equivalent (SWE) and snow depth as predicted by the Snow Data Assimilation System (SNODAS) to field measurements of SWE and snow depth. We examined locations on elk (Cervus canadensis) winter ranges in western Wyoming, because modeled data such as SNODAS output are often used for inferences on elk ecology. Overall, SNODAS predictions tended to overestimate field measurements, prediction uncertainty was high, and the difference between SNODAS predictions and field measurements was greater in snow shadows for both snow variables compared to non-snow shadow areas. We used a simple simulation of snow effects on the probability of an elk being killed by a predator to show that, if SNODAS prediction uncertainty was ignored, we might have mistakenly concluded that SWE was not an important factor in where elk were killed in predatory attacks during the winter. In this simulation, we were interested in the effects of snow at finer scales (2) than the resolution of SNODAS. If bias were to decrease when SNODAS predictions are averaged over coarser scales, SNODAS would be applicable to population-level ecology studies. In our study, however, averaging predictions over moderate to broad spatial scales (9–2200 km2) did not reduce the differences between SNODAS predictions and field measurements. This study highlights the need to carefully evaluate two issues when using model output as an explanatory variable in subsequent analysis: (1) the model’s resolution relative to the scale of the ecological question of interest and (2) the implications of prediction uncertainty on inferences when using model predictions as explanatory or predictor variables.

Paul C Cross;Robert W Klaver;Angela Brennan;Scott Creel;Jon P. Beckmann;Megan Higgs;Brandon M. Scurlock

2013-01-01

102

Evolutionary and Ecological Genomics of Non-Model Plants  

PubMed Central

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

Song, Bao-Hua; Mitchell-Olds, Thomas

2011-01-01

103

Putting the "Ecology" into Environmental Flows: Ecological Dynamics and Demographic Modelling  

NASA Astrophysics Data System (ADS)

There have been significant diversions of water from rivers and streams around the world; natural flow regimes have been perturbed by dams, barriers and excessive extractions. Many aspects of the ecological `health' of riverine systems have declined due to changes in water flows, which has stimulated the development of thinking about the maintenance and restoration of these systems, which we refer to as environmental flow methodologies (EFMs). Most existing EFMs cannot deliver information on the population viability of species because they: (1) use habitat suitability as a proxy for population status; (2) use historical time series (usually of short duration) to forecast future conditions and flow sequences; (3) cannot, or do not, handle extreme flow events associated with climate variability; and (4) assume process stationarity for flow sequences, which means the past sequences are treated as good indicators of the future. These assumptions undermine the capacity of EFMs to properly represent risks associated with different flow management options; assumption (4) is untenable given most climate-change predictions. We discuss these concerns and advocate the use of demographic modelling as a more appropriate tool for linking population dynamics to flow regime change. A `meta-species' approach to demographic modelling is discussed as a useful step from habitat based models towards modelling strategies grounded in ecological theory when limited data are available on flow-demographic relationships. Data requirements of demographic models will undoubtedly expose gaps in existing knowledge, but, in so doing, will strengthen future efforts to link changes in river flows with their ecological consequences.

Shenton, Will; Bond, Nicholas R.; Yen, Jian D. L.; Mac Nally, Ralph

2012-07-01

104

POPULATION MODELS IN ECOLOGICAL RISK ASSESSMENT  

EPA Science Inventory

A SETAC Pellston Workshop on Population-Level Risk Assessment was held in Roskilde, Denmark on 23-27 August 2003. One aspect of this workshop focused on modeling approaches for characterizing population-level effects of chemical exposure. The modeling work group identified th...

105

Inferential consequences of modeling rather than measuring snow accumulation in studies of animal ecology.  

PubMed

It is increasingly common for studies of animal ecology to use model-based predictions of environmental variables as explanatory or predictor variables, even though model prediction uncertainty is typically unknown. To demonstrate the potential for misleading inferences when model predictions with error are used in place of direct measurements, we compared snow water equivalent (SWE) and snow depth as predicted by the Snow Data Assimilation System (SNODAS) to field measurements of SWE and snow depth. We examined locations on elk (Cervus canadensis) winter ranges in western Wyoming, because modeled data such as SNODAS output are often used for inferences on elk ecology. Overall, SNODAS predictions tended to overestimate field measurements, prediction uncertainty was high, and the difference between SNODAS predictions and field measurements was greater in snow shadows for both snow variables compared to non-snow shadow areas. We used a simple simulation of snow effects on the probability of an elk being killed by a predator to show that, if SNODAS prediction uncertainty was ignored, we might have mistakenly concluded that SWE was not an important factor in where elk were killed in predatory attacks during the winter. In this simulation, we were interested in the effects of snow at finer scales (< 1 km2) than the resolution of SNODAS. If bias were to decrease when SNODAS predictions are averaged over coarser scales, SNODAS would be applicable to population-level ecology studies. In our study, however, averaging predictions over moderate to broad spatial scales (9-2200 km2) did not reduce the differences between SNODAS predictions and field measurements. This study highlights the need to carefully evaluate two issues when using model output as an explanatory variable in subsequent analysis: (1) the model's resolution relative to the scale of the ecological question of interest and (2) the implications of prediction uncertainty on inferences when using model predictions as explanatory or predictor variables. PMID:23734491

Brennan, Angela; Cross, Paul C; Higgs, Megan; Beckmann, Jon P; Klaver, Robert W; Scurlock, Brandon M; Creel, Scott

2013-04-01

106

Agent-based modeling and simulation in construction  

Microsoft Academic Search

Agent-based modeling and simulation (ABMS) is a relatively new development that has found extensive use in areas such as social sciences, economics, biology, ecology etc. Can ABMS be effectively used in finding answers to complex construction systems? Our focus is to provide some answers to this question. Initial experimentation is conducted to understand the advantages of using ABMS either in

Anil Sawhney; H. Bashford; K. Walsh; A. R. Mulky

2003-01-01

107

Simulation model verification and validation  

Microsoft Academic Search

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

Robert G. Sargent

1991-01-01

108

Verifying and validating simulation models  

Microsoft Academic Search

This paper discusses verification and validation 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; and a recommended procedureispresented.

Robert G. Sargent

1996-01-01

109

Verifying and validating simulation models  

Microsoft Academic Search

This paper discusses verification and validation of simulation models. The different approaches to deciding model validity am 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; and a recommended procedure is presented.

Robert G. Sargent

1996-01-01

110

Simulation model verification and validation  

Microsoft Academic Search

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

Robert G. Sargent

1991-01-01

111

Ecological prediction with nonlinear multivariate time-frequency functional data models  

USGS Publications Warehouse

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.

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

2013-01-01

112

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...

113

Realism and Relevance of Ecological Models Used in Chemical Risk Assessment  

Microsoft Academic Search

Ecological models have been developed and used in management of renewable natural resources, conservation biology, and assessments of ecological risks posed by toxic chemicals and other stressors. Because few models have been developed specifically for use in assessing chemical risks, this study examines the realism and relevance of a wide range of ecological models from the perspective of assessing toxicological

Steven M. Bartell; Robert A. Pastorok; H. Resit Akçakaya; Helen Regan; Scott Ferson; Christopher Mackay

2003-01-01

114

Relationship of stream ecological conditions to simulated hydraulic metrics across a gradient of basin urbanization  

USGS Publications Warehouse

The relationships among urbanization, stream hydraulics, and aquatic biology were investigated across a gradient of urbanization in 30 small basins in eastern Wisconsin, USA. Simulation of hydraulic metrics with 1-dimensional unsteady flow models was an effective means for mechanistically coupling the effects of urbanization with stream ecological conditions (i.e., algae, invertebrates, and fish). Urbanization, characterized by household, road, and urban land density, was positively correlated with the lowest shear stress for 2 adjacent transects in a reach for the low-flow summer (p < 0.001) and autumn (p < 0.01) periods. Urbanization also was positively correlated with Reynolds number and % exposed stream bed during months with moderate to low flows. Our study demonstrated the value of temporally and spatially explicit hydraulic models for providing mechanistic insight into the relationships between hydraulic variables and biological responses. For example, the positive correlation between filter-feeding invertebrate richness and minimum 2-transect shear stress observed in our study is consistent with a higher concentration of water-column particulates available for filtration. The strength of correlations between hydraulic and biological metrics is related to the time period (annual, seasonal, or monthly) considered. The hydraulic modeling approach, whether based on hourly or daily flow data, allowed documentation of the effects of a spatially variable response within a reach, and the results suggest that stream response to urbanization varies with hydraulic habitat type. ?? North American Benthological Society.

Steuer, J.J.; Bales, J.D.; Giddings, E.M.P.

2009-01-01

115

An Ecological Process Model of Systems Change  

Microsoft Academic Search

In June 2007 the American Journal of Community Psychology published a special issue focused on theories, methods and interventions for systems change which included calls from the\\u000a editors and authors for theoretical advancement in this field. We propose a conceptual model of systems change that integrates\\u000a familiar and fundamental community psychology principles (succession, interdependence, cycling of resources, adaptation) and\\u000a accentuates

Leslea J. Peirson; Katherine M. Boydell; H. Bruce Ferguson; Lorraine E. Ferris

2011-01-01

116

Correlated percolation models of structured habitat in ecology  

NASA Astrophysics Data System (ADS)

Percolation offers acknowledged models of random media when the relevant medium characteristics can be described as a binary feature. However, when considering habitat modeling in ecology, a natural constraint comes from nearest-neighbor correlations between the suitable/unsuitable states of the spatial units forming the habitat. Such constraints are also relevant in the physics of aggregation where underlying processes may lead to a form of correlated percolation. However, in ecology, the processes leading to habitat correlations are in general not known or very complex. As proposed by Hiebeler (2000), these correlations can be captured in a lattice model by an observable aggregation parameter q, supplementing the density p of suitable sites. We investigate this model as an instance of correlated percolation. We analyze the phase diagram of the percolation transition and compute the cluster size distribution, the pair-connectedness function C(r) and the correlation function g(r). We find that while g(r) displays a power-law decrease associated with long-range correlations in a wide domain of parameter values, critical properties are compatible with the universality class of uncorrelated percolation. We contrast the correlation structures obtained respectively for the correlated percolation model and for the Ising model, and show that the diversity of habitat configurations generated by the Hiebeler model is richer than the archetypal Ising model. We also find that emergent structural properties are peculiar to the implemented algorithm, leading to questioning the notion of a well-defined model of aggregated habitat. We conclude that the choice of model and algorithm has strong consequences on what insights ecological studies can get using such models of species habitat.

Huth, Géraldine; Lesne, Annick; Munoz, François; Pitard, Estelle

2014-12-01

117

Mathematical Modeling of Plant Allelopathic Hormesis Based on Ecological-Limiting-Factor Models  

PubMed Central

Allelopathy arises from the release of chemicals by one plant species that affect other species in its vicinity, usually to their detriment. Allelopathic effects have been demonstrated to be limiting factors for species distributions and ecological processes in some natural or agricultural communities. Based on the biphasic hormetic responses of plants to allelochemicals, ecological-limiting-factor models were introduced into the An-Johnson-Lovett hormesis model to improve modelling the phenomenon of allelopathic hormesis and to better reflect the nature of allelopathy as a limiting factor in ecological processes. Outcomes of the models have been compared for several sets of experimental data from the literature and good agreement between the models and data was observed, which indicates that the new models give some insight into the ecological mechanisms involved and may provide more options for modelling the allelopathic phenomenon as well as platforms for further research on plant allelopathic hormesis. PMID:21431081

Liu, Yinghu; Chen, Xiaoqiu; Duan, Shunshan; Feng, Yuanjiao; An, Min

2010-01-01

118

Modeling hydrologic and ecologic responses using a new eco-hydrological model for identification of droughts  

NASA Astrophysics Data System (ADS)

severely damages water and agricultural resources, and both hydrological and ecological responses are important for its understanding. First, precipitation deficit induces soil moisture deficiency and high plant water stress causing agricultural droughts. Second, hydrological drought characterized by deficit of river discharge and groundwater follows agricultural drought. However, contributions of vegetation dynamics to these processes at basin scale have not been quantified. To address this issue, we develop an eco-hydrological model that can calculate river discharge, groundwater, energy flux, and vegetation dynamics as diagnostic variables at basin scale within a distributed hydrological modeling framework. The model is applied to drought analysis in the Medjerda River basin. From model inputs and outputs, we calculate drought indices for different drought types. The model shows reliable accuracy in reproducing observed river discharge in long-term (19 year) simulation. Moreover, the drought index calculated from the model-estimated annual peak of leaf area index correlates well (correlation coefficient r = 0.89) with the drought index from nationwide annual crop production, which demonstrates that the modeled leaf area index is capable of representing agricultural droughts related to historical food shortages. We show that vegetation dynamics have a more rapid response to meteorological droughts than river discharge and groundwater dynamics in the Medjerda basin because vegetation dynamics are sensitive to soil moisture in surface layers, whereas soil moisture in deeper layers strongly contributes to streamflow and groundwater level. Our modeling framework can contribute to analyze drought progress, although analyses for other climate conditions are needed.

Sawada, Yohei; Koike, Toshio; Jaranilla-Sanchez, Patricia Ann

2014-07-01

119

Applying ecological modeling to parenting for Australian refugee families.  

PubMed

Children in families with parents from refugee backgrounds are often viewed as a vulnerable group with increased risks of developing physical or psychological problems. However, there is very little research regarding the strategies that parents might use to parent their children in a new country while they also manage the interrelated challenges of poverty, social isolation, maternal stress, and mental ill health that often go along with resettlement. We explore the application of ecological modeling, specifically at individual, institutional, and policy levels, within an Australian context to critique the factors that shape the development of parenting capacity within refugee families settling in a new Western country. Ecological modeling enables examination of how public policy at local state and national levels influences the individual and family directly and through the organizations that are given the task of implementing many of the policy recommendations. Recommendations for health practice and research are made. PMID:24583875

Grant, Julian; Guerin, Pauline B

2014-10-01

120

Structural Equation Modeling: Applications in Ecological and Evolutionary Biology Research  

USGS Publications Warehouse

This book presents an introduction to the methodology of structural equation modeling, illustrates its use, and goes on to argue that it has revolutionary implications for the study of natural systems. A major theme of this book is that we have, up to this point, attempted to study systems primarily using methods (such as the univariate model) that were designed only for considering individual processes. Understanding systems requires the capacity to examine simultaneous influences and responses. Structural equation modeling (SEM) has such capabilities. It also possesses many other traits that add strength to its utility as a means of making scientific progress. In light of the capabilities of SEM, it can be argued that much of ecological theory is currently locked in an immature state that impairs its relevance. It is further argued that the principles of SEM are capable of leading to the development and evaluation of multivariate theories of the sort vitally needed for the conservation of natural systems. Supplementary information can be found at the authors website, http://www.jamesbgrace.com/. ? Details why multivariate analyses should be used to study ecological systems ? Exposes unappreciated weakness in many current popular analyses ? Emphasizes the future methodological developments needed to advance our understanding of ecological systems.

Pugesek, Bruce H.; von Eye, Alexander; Tomer, Adrian

2003-01-01

121

I. Introduction Simulation Modeling  

E-print Network

, figure of merit, design of experiments, software testing, software validation, program referability, experimentation technique, simulation methodology, and software engineering. Key Words and Phrases: assessment, program efficiency, code verification, software reliability, software robustness, software certification

Tesfatsion, Leigh

122

Ecological Modelling 192 (2006) 143159 Nitrogen transformation and transport modeling  

E-print Network

of nitrogen species in groundwater aquifers. © 2005 Elsevier B.V. All rights reserved. Keywords: Nitrogen, originating from agricultural sites, animal feedlots, septic tanks and other waste disposal sites, is one.V. All rights reserved. doi:10.1016/j.ecolmodel.2005.07.013 #12;144 M.-S. Lee et al. / Ecological

Clement, Prabhakar

123

Opportunities for using the EOS Imaging Spectrometers and synthetic aperture radar in ecological models  

NASA Technical Reports Server (NTRS)

Several promising approaches to assessing biochemical and architectural properties of landscapes are outlined. Strategies for using new EOS sensors in ecological models are examined. Ways in which ecological and remote sensing models can utilize information provided by the new sensors to characterize ecological properties at coarse scales and to estimate within-ecosystem properties are addressed.

Ustin, Susan L.; Wessman, Carol A.; Curtiss, Brian; Kasischke, Eric; Way, Jobea; Vanderbilt, Vern C.

1991-01-01

124

Validating simulation models  

Microsoft Academic Search

In this paper we give a general introduction to model validation, define the various validation techniques, discuss conceptual and operational validity, and present a recommended model validation procedure.

Robert G. Sargent

1983-01-01

125

Automatic programming of simulation models  

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

126

Ecological Modelling 110 (1998) 175207 Individual-based model of sympatric populations of brown and  

E-print Network

and rainbow trout for instream flow assessment: model description and calibration W. Van Winkle a, *, H Elsevier Science B.V. All rights reserved. PII S0304-3800(98)00065-9 #12;W. Van Winkle et al. / Ecological

Jager, Henriette I.

127

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

PubMed

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

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

128

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

PubMed Central

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.

Wang, Hui-Yu; Höök, Tomas O

2009-01-01

129

Modeling the integrated ecology, biogeochemistry, and hydrology of the global terrestrial biosphere in the Community Land Model (CLM4) (Invited)  

NASA Astrophysics Data System (ADS)

Terrestrial ecosystems influence climate through physical, chemical, and biological processes that affect planetary energetics, the hydrologic cycle, and atmospheric composition. Much of our understanding of how terrestrial ecosystems affect climate comes from numerical models of Earth’s climate and their representation of the terrestrial biosphere. These models initially simulated only hydrometeorological processes at the land surface. They have since evolved to simulate the coupled ecology, biogeochemistry, and hydrology of terrestrial ecosystems so that the biosphere and atmosphere form a coupled system. As such, the simulated hydrologic cycle is an emergent property of the ecology and biogeochemistry represented in the model. Here, we use the Community Land Model (CLM4), the land component of the Community Earth System Model, to examine interactions among hydrology, ecology, and biogeochemistry with respect to energy, water, and carbon fluxes. Specifically, carbon uptake during gross primary production (GPP) is linked to water loss during evapotranspiration (ET). Model functional errors in the parameterization of canopy radiative transfer, leaf photosynthesis and stomatal conductance, and canopy scaling lead to substantial errors in simulated GPP and ET. Improvements to these parameterizations gained from theoretical considerations and empirical studies reduce biases in GPP, with concomitant improvement in ET. Most of the bias reduction comes from the revised photosynthesis-stomatal conductance formulation; improved canopy radiation has lesser effect; and changes to canopy scaling have minor effect. A key model parameter is the maximum rate of leaf carboxylation, which is highly uncertain for large-scale climate models and for which various disparate estimates have been published. The effect of model parameter errors on GPP and ET is of comparable magnitude to that of model functional errors and offset bias reductions from improved model parameterizations. Our results imply that this key leaf-level physiological parameter cannot be defined independent of model-specific parameterizations. Our analyses suggest that we still have much to learn about the biochemistry of photosynthesis, the biophysics of evapotranspiration, their interdependencies, and how to represent these processes in models of the terrestrial biosphere for climate simulation.

Bonan, G. B.; Lawrence, P.; Oleson, K. W.; Levis, S.

2010-12-01

130

Progress in modeling and simulation.  

PubMed

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

Kindler, E

1998-01-01

131

Advanced Space Shuttle simulation model  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

132

Informatica 25 (2001) xxxyyy 1 Multi-attribute modelling of economic and ecological impacts of  

E-print Network

, The Netherlands Keywords: qualitative multi-attribute modelling, genetically modified plants, cropping system project "Soil ecological and economic evaluation of genetically modified crops". One of the goals and ecological impacts of using genetically modified crops, with special emphasis on soil biology and ecology

Bohanec, Marko

133

New model diagnostics for spatio-temporal systems in epidemiology and ecology.  

PubMed

A cardinal challenge in epidemiological and ecological modelling is to develop effective and easily deployed tools for model assessment. The availability of such methods would greatly improve understanding, prediction and management of disease and ecosystems. Conventional Bayesian model assessment tools such as Bayes factors and the deviance information criterion (DIC) are natural candidates but suffer from important limitations because of their sensitivity and complexity. Posterior predictive checks, which use summary statistics of the observed process simulated from competing models, can provide a measure of model fit but appropriate statistics can be difficult to identify. Here, we develop a novel approach for diagnosing mis-specifications of a general spatio-temporal transmission model by embedding classical ideas within a Bayesian analysis. Specifically, by proposing suitably designed non-centred parametrization schemes, we construct latent residuals whose sampling properties are known given the model specification and which can be used to measure overall fit and to elicit evidence of the nature of mis-specifications of spatial and temporal processes included in the model. This model assessment approach can readily be implemented as an addendum to standard estimation algorithms for sampling from the posterior distributions, for example Markov chain Monte Carlo. The proposed methodology is first tested using simulated data and subsequently applied to data describing the spread of Heracleum mantegazzianum (giant hogweed) across Great Britain over a 30-year period. The proposed methods are compared with alternative techniques including posterior predictive checking and the DIC. Results show that the proposed diagnostic tools are effective in assessing competing stochastic spatio-temporal transmission models and may offer improvements in power to detect model mis-specifications. Moreover, the latent-residual framework introduced here extends readily to a broad range of ecological and epidemiological models. PMID:24522782

Lau, Max S Y; Marion, Glenn; Streftaris, George; Gibson, Gavin J

2014-04-01

134

From actors to agents in socio-ecological systems models  

PubMed Central

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

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

2012-01-01

135

Modelling dendritic ecological networks in space: anintegrated network perspective  

USGS Publications Warehouse

the context of stream ecology. Within this context, we summarise the key innovations of a new family of spatial statistical models that describe spatial relationships in DENs. Finally, we discuss how different network analyses may be combined to address more complex and novel research questions. While our main focus is streams, the taxonomy of network analyses is also relevant anywhere spatial patterns in both network and 2-D space can be used to explore the influence of multi-scale processes on biota and their habitat (e.g. plant morphology and pest infestation, or preferential migration along stream or road corridors).

Peterson, Erin E.; Ver Hoef, Jay M.; Isaak, Dan J.; Falke, Jeffrey A.; Fortin, Marie-Josée; Jordon, Chris E.; McNyset, Kristina; Monestiez, Pascal; Ruesch, Aaron S.; Sengupta, Aritra; Som, Nicholas; Steel, E. Ashley; Theobald, David M.; Torgersen, Christian E.; Wenger, Seth J.

2013-01-01

136

Homogenization of Large-Scale Movement Models in Ecology  

USGS Publications Warehouse

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. ?? 2010 Society for Mathematical Biology.

Garlick, M.J.; Powell, J.A.; Hooten, M.B.; McFarlane, L.R.

2011-01-01

137

Ecological niche modeling and differentiation of populations of *Triatoma brasiliensis* Neiva, 1911, the most important Chagas disease vector in northeastern Brazil (Hemiptera, Reduviidae, Triatominae)  

E-print Network

Ecologic niche modeling has allowed numerous advances in understanding the geographic ecology of species, including distributionalpredictions, distributionalchange and invasion, and assessment of ecologic differences. We ...

Costa, Jane; Peterson, A. Townsend; Beard, C. Ben

2002-11-01

138

Pattern-oriented modeling of agent-based complex systems: lessons from ecology.  

PubMed

Agent-based complex systems are dynamic networks of many interacting agents; examples include ecosystems, financial markets, and cities. The search for general principles underlying the internal organization of such systems often uses bottom-up simulation models such as cellular automata and agent-based models. No general framework for designing, testing, and analyzing bottom-up models has yet been established, but recent advances in ecological modeling have come together in a general strategy we call pattern-oriented modeling. This strategy provides a unifying framework for decoding the internal organization of agent-based complex systems and may lead toward unifying algorithmic theories of the relation between adaptive behavior and system complexity. PMID:16284171

Grimm, Volker; Revilla, Eloy; Berger, Uta; Jeltsch, Florian; Mooij, Wolf M; Railsback, Steven F; Thulke, Hans-Hermann; Weiner, Jacob; Wiegand, Thorsten; DeAngelis, Donald L

2005-11-11

139

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

Microsoft Academic Search

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

Kenneth H. Reckhow

1994-01-01

140

Modeling, Simulation, and Visualization  

E-print Network

current representation) and dynamic re-planning during model execution. · Go beyond if ­ then planning the occurrence of events to situational awareness by logging the events in the Situational Awareness data base & Information Sciences Division Argonne, IL 60439-4832 phone: 630.252.5308 vang@anl.gov LBC Sponsor:Mr. Morris G

Kemner, Ken

141

Verification of Computer Simulation Models  

Microsoft Academic Search

The problem of validating computer simulation models of industrial systems has received only limited attention in the management science literature. The purpose of this paper is to consider the problem of validating computer models in the light of contemporary thought in the fields of philosophy of science, economic theory, and statistics. In order to achieve this goal we have attempted

Thomas H. Naylor; J. M. Finger

1967-01-01

142

Ecological Modelling 126 (2000) 7377 Leslie model for predatory gall-midge population  

E-print Network

Ecological Modelling 126 (2000) 73­77 Leslie model for predatory gall-midge population Vlastimil´ Budejo6ice, Czech Republic Accepted 16 August 1999 Abstract A Leslie matrix model for predatory gall-midge is used in biological control. We compare the two common parametrizations of Leslie matrix., i.e. the flow

Krivan, Vlastimil

143

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

Microsoft Academic Search

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

Ferdinando Villa

2001-01-01

144

Modeling socioeconomic and ecologic aspects of land-use change  

SciTech Connect

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.

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

1992-01-01

145

Ecological footprint model using the support vector machine technique.  

PubMed

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

Ma, Haibo; Chang, Wenjuan; Cui, Guangbai

2012-01-01

146

Numerical models of salt marsh evolution: ecological, geomorphic, and climatic factors  

USGS Publications Warehouse

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.

Fagherazzi, Sergio; Kirwan, Matthew L.; Mudd, Simon M.; Guntenspergen, Glenn R.; Temmerman, Stijn; D'Alpaos, Andrea; van de Koppel, Johan; Rybczyk, John; Reyes, Enrique; Craft, Chris; Clough, Jonathan

2012-01-01

147

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

USGS Publications Warehouse

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.

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

148

Verification And Validation Of Simulation Models  

Microsoft Academic Search

The Hierarchical Modeling and Simulation System (HI-MASS) is a prototype modeling and simulation system that supports modeling based on the Hierarchical Control Flow Graph Model paradigm and simulation execution using a sequential synchronous simulation algorithm. The prototype is an object oriented C++ based system designed for a Unix environment and implemented using freely available software tools. Models are specified using

Douglas G. Fritz; Robert G. Sargent; Thorsten Daum

1995-01-01

149

treedyn3 forest simulation model  

Microsoft Academic Search

The treedyn3 forest simulation model is a process model of tree growth, carbon and nitrogen dynamics in a single-species, even-aged forest stand. It is based on the treedyn model. Major changes include the computation of sun angle and radiation as a function of latitude and day of the year, the closed-form integration of canopy production as a function of day

Hartmut Bossel

1996-01-01

150

Solanum nigrum: a model ecological expression system and its tools.  

PubMed

Plants respond to environmental stresses through a series of complicated phenotypic responses, which can be understood only with field studies because other organisms must be recruited for their function. If ecologists are to fully participate in the genomics revolution and if molecular biologists are to understand adaptive phenotypic responses, native plant ecological expression systems that offer both molecular tools and interesting natural histories are needed. Here, we present Solanum nigrum L., a Solanaceous relative of potato and tomato for which many genomic tools are being developed, as a model plant ecological expression system. To facilitate manipulative ecological studies with S. nigrum, we describe: (i) an Agrobacterium-based transformation system and illustrate its utility with an example of the antisense expression of RuBPCase, as verified by Southern gel blot analysis and real-time quantitative PCR; (ii) a 789-oligonucleotide microarray and illustrate its utility with hybridizations of herbivore-elicited plants, and verify responses with RNA gel blot analysis and real-time quantitative PCR; (iii) analyses of secondary metabolites that function as direct (proteinase inhibitor activity) and indirect (herbivore-induced volatile organic compounds) defences; and (iv) growth and fitness-estimates for plants grown under field conditions. Using these tools, we demonstrate that attack from flea beetles elicits: (i) a large transcriptional change consistent with elicitation of both jasmonate and salicylate signalling; and (ii) increases in proteinase inhibitor transcripts and activity, and volatile organic compound release. Both flea beetle attack and jasmonate elicitation increased proteinase inhibitors and jasmonate elicitation decreased fitness in field-grown plants. Hence, proteinase inhibitors and jasmonate-signalling are targets for manipulative studies. PMID:15078438

Schmidt, Dominik D; Kessler, André; Kessler, Danny; Schmidt, Silvia; Lim, Michelle; Gase, Klaus; Baldwin, Ian T

2004-05-01

151

Spatial agent-based models for socio-ecological systems: Challenges and prospectsq  

E-print Network

, (3) integration of socio-demographic, ecological, and biophysical models, and (4) spatial. This exploration is especially relevant when dynamics involve abrupt changes, crises and critical transitions

Tesfatsion, Leigh

152

Stochastic models: theory and simulation.  

SciTech Connect

Many problems in applied science and engineering involve physical phenomena that behave randomly in time and/or space. Examples are diverse and include turbulent flow over an aircraft wing, Earth climatology, material microstructure, and the financial markets. Mathematical models for these random phenomena are referred to as stochastic processes and/or random fields, and Monte Carlo simulation is the only general-purpose tool for solving problems of this type. The use of Monte Carlo simulation requires methods and algorithms to generate samples of the appropriate stochastic model; these samples then become inputs and/or boundary conditions to established deterministic simulation codes. While numerous algorithms and tools currently exist to generate samples of simple random variables and vectors, no cohesive simulation tool yet exists for generating samples of stochastic processes and/or random fields. There are two objectives of this report. First, we provide some theoretical background on stochastic processes and random fields that can be used to model phenomena that are random in space and/or time. Second, we provide simple algorithms that can be used to generate independent samples of general stochastic models. The theory and simulation of random variables and vectors is also reviewed for completeness.

Field, Richard V., Jr.

2008-03-01

153

Evolutionary model on market ecology of investors and investments  

NASA Astrophysics Data System (ADS)

The interactions between investors and investments are of significant importance to understand the dynamics of financial markets. An evolutionary model is proposed to investigate the dynamic behaviors of investors and investments in a market ecology. The investors are divided into two groups, active ones and passive ones, distinguished by different selection capabilities based on the partial information, while the investments are simply categorized as good ones and bad ones. Without external influence, the system consisting of both investors and investments can self-organize to a quasi-stationary state according to their own strategies associating with the gains of market information. The model suggests that the partial information asymmetry of investors and various qualities of investments commonly give rise to a diverse dynamic behavior of the system by quantifying the fraction of active investors and of good investment at the quasi-stationary state.

Gao, Ya-Chun; Cai, Shi-Min; Lü, Linyuan; Wang, Bing-Hong

2013-08-01

154

Automatic programming of simulation models  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

155

Ecological Modelling xxx (2005) xxxxxx Modelling carbon and water cycles in a beech forest  

E-print Network

Ecological Modelling xxx (2005) xxx­xxx Modelling carbon and water cycles in a beech forest Part II and heterotrophic respirations, net ecosystem exchange, wood and root growth) and the water cycle (transpiration, soil evaporation, interception, drainage and soil water status) is tested with data from a young beech

Boyer, Edmond

156

Ecological Modelling 143 (2001) 227243 A globally applicable model of daily solar irradiance  

E-print Network

Ecological Modelling 143 (2001) 227­243 A globally applicable model of daily solar irradiance at many ground stations, the total daily solar irradiance (Rs) received at the earth's surface to measured solar irradiance. In a global comparison for the year 1987, VP-RAD-estimated and satellite

Hunt Jr., E. Raymond

157

Economic Analysis. Computer Simulation Models.  

ERIC Educational Resources Information 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…

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

158

Simulating landscape change in the Olympic Peninsula using spatial ecological and socioeconomic data  

SciTech Connect

Ecological and socioeconomic data were integrated to study landscape change for the Dungeness River basin in the Olympic Peninsula, Washington State. A multinomial logit procedure was used to evaluate twenty-two maps representing various data themes to derive transition probabilities of land cover change. Probabilities of forest disturbance were greater on private land than public. Between 1975 and 1988, forest cover increased, grassy/brushy covers decreased, and the number of forest patches increased about 30%. Simulations were run to estimate future land cover. These results were represented as frequency distributions for proportion cover and patch characteristics.

Flamm, R.O. (Florida Marine Research Institute, St. Petersburg, FL (United States)); Gottfried, R. (Univ. of the South, Sewanee, TN (United States)); Lee, R.G.; Naiman, R.J. (Univ. of Washington, Seattle, WA (United States)); Turner, M.G. (Oak Ridge National Laboratory, TN (United States)); Wear, D. (USDA Forest Service, Research Triangle Park, NC (United States))

1994-06-01

159

Collective Philanthropy: Describing and Modeling the Ecology of Giving  

PubMed Central

Reflective of income and wealth distributions, philanthropic gifting appears to follow an approximate power-law size distribution as measured by the size of gifts received by individual institutions. We explore the ecology of gifting by analysing data sets of individual gifts for a diverse group of institutions dedicated to education, medicine, art, public support, and religion. We find that the detailed forms of gift-size distributions differ across but are relatively constant within charity categories. We construct a model for how a donor's income affects their giving preferences in different charity categories, offering a mechanistic explanation for variations in institutional gift-size distributions. We discuss how knowledge of gift-sized distributions may be used to assess an institution's gift-giving profile, to help set fundraising goals, and to design an institution-specific giving pyramid. PMID:24983864

Gottesman, William L.; Reagan, Andrew James; Dodds, Peter Sheridan

2014-01-01

160

Collective Philanthropy: Describing and Modeling the Ecology of Giving  

E-print Network

Reflective of income and wealth distributions, philanthropic gifting appears to follow an approximate power-law size distribution as measured by the size of gifts received by individual institutions. We explore the ecology of gifting by analysing data sets of individual gifts for a diverse group of institutions dedicated to education, medicine, art, public support, and religion. We find that the detailed forms of gift-size distributions differ across but are relatively constant within charity categories. We construct a model for how a donor's income affects their giving preferences in different charity categories, offering a mechanistic explanation for variations in institutional gift-size distributions. We discuss how knowledge of gift-sized distributions may be used to assess an institution's gift-giving profile, to help set fundraising goals, and to design an institution-specific giving pyramid.

Gottesman, William L; Dodds, Peter Sheridan

2013-01-01

161

Collective philanthropy: describing and modeling the ecology of giving.  

PubMed

Reflective of income and wealth distributions, philanthropic gifting appears to follow an approximate power-law size distribution as measured by the size of gifts received by individual institutions. We explore the ecology of gifting by analysing data sets of individual gifts for a diverse group of institutions dedicated to education, medicine, art, public support, and religion. We find that the detailed forms of gift-size distributions differ across but are relatively constant within charity categories. We construct a model for how a donor's income affects their giving preferences in different charity categories, offering a mechanistic explanation for variations in institutional gift-size distributions. We discuss how knowledge of gift-sized distributions may be used to assess an institution's gift-giving profile, to help set fundraising goals, and to design an institution-specific giving pyramid. PMID:24983864

Gottesman, William L; Reagan, Andrew James; Dodds, Peter Sheridan

2014-01-01

162

Integrated Bayesian network framework for modeling complex ecological issues.  

PubMed

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

Johnson, Sandra; Mengersen, Kerrie

2012-07-01

163

Advanced Space Shuttle simulation model  

NASA Technical Reports Server (NTRS)

The effects of atmospheric turbulence in horizontal and near-horizontal flight during the return of the Space Shuttle are important for determining design, control, and pilot-in-the-loop effects. A nonrecursive model (based on vonKarman spectra) for atmospheric turbulence along the flight path of the Shuttle Orbiter has been developed which provides for simulation of instantaneous vertical and horizontal gusts at the vehicle center-of-gravity and also for simulation of instantaneous gust gradients. Based on this model the time series for gusts and gust gradients have been generated and stored on a series of magnetic tapes which are 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, and conclusions and recommendations are presented. Appendices provide tabulated one-dimensional vonKarman spectra, a discussion of the minimum frequency simulated, and the results of spectral and statistical analyses of the SSTT.

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

1982-01-01

164

Modeling and Simulation for Safeguards  

SciTech Connect

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.

Swinhoe, Martyn T. [Los Alamos National Laboratory

2012-07-26

165

The HWVP availability simulation model  

SciTech Connect

This report described the hanford Waste Vitrification Plant simualtion model (HWVP).The model was utilized to simulate the performance and repair of remote handling equipment utilizied at the vitrification plant. The simulation model demonstrates that the HWVP has an availability of {approx} 85%. It also shows that both the MC and CDC cranes have a high utilization factor of {approx} 70%. This means that the crane`s idle time of {approx} 30% may not be sufficient to meet off-normal events such as canister rework. A study is recommended to optimize the crane operations in these areas. The ST/ET crane`s utilization factor is 16%, indicating that it can meet upset conditions. The analysis also shows that the canyon crane has a utilization factor of 29%, or it is idle 61% of the time. This large amount of inactive time demonstrates that the crane can service failed equipment without affecting production.

Reisdorf, J.; Sienko, F.; Melville, D.; Gogg, T.

1994-12-31

166

Social network models predict movement and connectivity in ecological landscapes  

USGS Publications Warehouse

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.

Fletcher, R.J., Jr.; Acevedo, M.A.; Reichert, B.E.; Pias, K.E.; Kitchens, W.M.

2011-01-01

167

Simulation Model Driven Engineering for Manufacturing Cell  

E-print Network

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

Paris-Sud XI, Université de

168

Simulation Framework for Teaching in Modeling and Simulation Areas  

ERIC Educational Resources Information Center

Simulation is the process of executing a model that describes a system with enough detail; this model has its entities, an internal state, some input and output variables and a list of processes bound to these variables. Teaching a simulation language such as general purpose simulation system (GPSS) is always a challenge, because of the way it…

De Giusti, Marisa Raquel; Lira, Ariel Jorge; Villarreal, Gonzalo Lujan

2008-01-01

169

Agrobacterium -mediated transformation of Nicotiana attenuata , a model ecological expression system  

Microsoft Academic Search

Summary.   Research into the genetic basis of the ecological sophistication of plants is hampered by the availability of transformable\\u000a systems with a wealth of well-described ecological interactions. We present an Agrobacterium-mediated transformation system for the model ecological expression system, Nicotiana attenuata, a native tobacco that occupies the post-fire niche in the Great Basin Desert of North America. We describe a

Tamara Krügel; Michelle Lim; Klaus Gase; Rayko Halitschke; Ian T. Baldwin

2002-01-01

170

Simulating spin models on GPU  

E-print Network

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.

Martin Weigel

2010-06-19

171

Identifying Droughts by Modeling the Hydrologic and Ecologic Responses in the Medjerda River Basin, Tunisia  

NASA Astrophysics Data System (ADS)

Drought brings severe damage to water and agricultural resources, and both of hydrological and ecological responses are important for understanding droughts. However, the ecological contributions to drought characteristics at the basin scale have not been quantified. To address this issue, we developed an eco-hydrological model that can calculate vegetation dynamics as a diagnostic valuable in a distributed-hydrological modeling framework and identified different drought types in the Medjerda River Basin where drought is a predominant issue. From the inputs and outputs of the model, we calculate drought indices for different drought types. The model shows reliable accuracy in reproducing the observed river discharge and the satellite observed leaf area index in the long-term (19-year) simulation. Moreover, the drought index calculated from model estimated annual peak of leaf area index is well correlated (correlation coefficient; r = 0.89; see Figure) with drought index from nationwide annual crop production, which show the modeled leaf area index has enough capacity to reproducing agricultural droughts that can be related with historical food shortage on 1988-1989 and 1993-1995. Our model can estimate vegetation dynamics and water cycle simultaneously in the enough accuracy to analyze the basin-scale agricultural and hydrological droughts separately. We clarify that vegetation dynamics has quicker response to meteorological droughts than river discharge and groundwater dynamics in Medjerda River Basin because vegetation dynamics is sensitive to soil moisture in surface layers while soil moisture in deeper layers strongly contributes to stream flow and depth of groundwater level. Therefore, historical agricultural droughts predominantly occurred prior to hydrological droughts and in the 1988-1989 drought, the hydrological drought lasted much longer even after crop production recovered. Standardized anomaly index (SA) for estimated annual maximum leaf area index (green line) from model and observed annual crop production in Tunisia (orange line).

Sawada, Y.; Koike, T.; Jaranilla-sanchez, P. A.

2013-12-01

172

Rule-based simulation models  

NASA Technical Reports Server (NTRS)

Procedural modeling systems, rule based modeling systems, and a method for converting a procedural model to a rule based model are described. Simulation models are used to represent real time engineering systems. A real time system can be represented by a set of equations or functions connected so that they perform in the same manner as the actual system. Most modeling system languages are based on FORTRAN or some other procedural language. Therefore, they must be enhanced with a reaction capability. Rule based systems are reactive by definition. Once the engineering system has been decomposed into a set of calculations using only basic algebraic unary operations, a knowledge network of calculations and functions can be constructed. The knowledge network required by a rule based system can be generated by a knowledge acquisition tool or a source level compiler. The compiler would take an existing model source file, a syntax template, and a symbol table and generate the knowledge network. Thus, existing procedural models can be translated and executed by a rule based system. Neural models can be provide the high capacity data manipulation required by the most complex real time models.

Nieten, Joseph L.; Seraphine, Kathleen M.

1991-01-01

173

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...

174

International Association for Ecology A Generalized, Lumped-Parameter Model of Photosynthesis, Evapotranspiration and Net  

E-print Network

International Association for Ecology A Generalized, Lumped-Parameter Model of Photosynthesis of this work. Publisher contact information may be obtained at . http A generalized, lumped-parameter model of photosynthesis, ?vapotranspiration and net primary production

New Hampshire, University of

175

Simulation Model Development and Analysis in UNITY  

Microsoft Academic Search

We evaluate UNITY - a computational model, specification language and proof system defined by Chandy and Misra (5) for the development of parallel and distributed programs - as a platform for simulation model specification and analysis. We describe a UNITY-based methodology for the construction, analysis and execution of simulation models. The methodology starts with a simulation model specification in the

Ernest H. Page; Marc Abrams

2001-01-01

176

An ecological model of developing researcher competence: the case of software technology in doctoral research  

Microsoft Academic Search

This paper presents an ecological model of developing researcher competence, with a particular focus on doctoral students’\\u000a use of research software. The model extends on theoretical work done by Young et al. (Instructional Science 30(1): 47–63, 2002), modelling the intentional dynamics of technological learning contexts. The development of the ecological\\u000a model is linked to existing ways of understanding the doctoral

Juup Stelma

2011-01-01

177

Simulation of Watershed Systems Using Component-Based Models  

NASA Astrophysics Data System (ADS)

Component-based modeling introduces an alternative approach for simulating watershed systems where a model can be composed of components from different disciplines, interlinked through shared boundary conditions. One advantage of component-based modeling is that it allows components to be created, tested, and maintained by independent groups, while still remaining compliant within a larger modeling system. By providing a basic framework in which components can be interlinked, watershed models can evolve more dynamically because groups are able to specialize in parts of the overall system. Despite these advantages of component-based modeling of watershed systems, there are also challenges. This paper addresses the metadata requirements for guiding development of a component-based watershed model so that different representations of the same process can be easily exchanged. We address this challenge by considering how two widely used watershed modeling systems, the Regional Hydro-Ecologic Simulation System (RHESSys) and the Soil and Water Assessment Tool (SWAT), can be decomposed into components. We then implement prototype components from these models using the Open Modeling Interface (OpenMI) and test how different component configurations can be assembled to simulate rainfall/runoff processes using the Coweeta Hydrologic Laboratory as our study area. The result of this work is proposed metadata requirements for the organization of a component-based watershed modeling system, focusing in particular on the classification of model components and the structure required to enable plug-and-play of model components.

Elag, M.; Goodall, J. L.

2011-12-01

178

A Conceptual Framework for Evaluating the Domains of Applicability of Ecological Models and its Implementation in the Ecological Production Function Library  

EPA Science Inventory

The use of computational ecological models to inform environmental management and policy has proliferated in the past 25 years. These models have become essential tools as linkages and feedbacks between human actions and ecological responses can be complex, and as funds for sampl...

179

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

ERIC Educational Resources Information Center

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

Stibbards, Adam; Puk, Tom

2011-01-01

180

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

ERIC Educational Resources Information Center

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…

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

2010-01-01

181

Towards Grid-Wide Modeling and Simulation  

E-print Network

Modeling and simulation permeate all areas of business, science and engineering. With the increase in the scale and complexity of simulations, large amounts of computational resources are required, and collaborative model ...

Xie, Yong

182

Predicting geographic and ecological distributions of triatomine species in the southern Mexican state of Puebla using ecological niche modeling.  

PubMed

We analyzed the geographic distribution using ecological niche modeling of three species of triatomines distributed in the Mexican state of Puebla. Punctual records were gathered for a period of 5 yr of fieldwork sampling. We used the genetic algorithm for rule-set production (GARP) to achieve the potential distribution of the ecological niche of triatomines. The models showed that Triatoma barberi and Meccus pallidipennis are sympatric and widely distributed in the central-southern part of the state, whereas T. dimidata is restricted to the northern mountains of the state with no overlapping among other species, M. bassolsae was not modeled because of the scarce number of locality records. We highlighted the warm and dry conditions in southern Puebla as important potential areas for triatomine presence. Finally, we correlated the species potential presence with the human population at risk of acquiring Chagas disease by vector-borne transmission; it is showed that M. pallidipennis presents the highest values of both ecological and poverty risk scenarios representing the main potential vector in the state. PMID:18533450

Sandoval-Ruiz, C A; Zumaquero-Rios, J L; Rojas-Soto, O R

2008-05-01

183

Locating Pleistocene Refugia: Comparing Phylogeographic and Ecological Niche Model Predictions  

PubMed Central

Ecological niche models (ENMs) provide a means of characterizing the spatial distribution of suitable conditions for species, and have recently been applied to the challenge of locating potential distributional areas at the Last Glacial Maximum (LGM) when unfavorable climate conditions led to range contractions and fragmentation. Here, we compare and contrast ENM-based reconstructions of LGM refugial locations with those resulting from the more traditional molecular genetic and phylogeographic predictions. We examined 20 North American terrestrial vertebrate species from different regions and with different range sizes for which refugia have been identified based on phylogeographic analyses, using ENM tools to make parallel predictions. We then assessed the correspondence between the two approaches based on spatial overlap and areal extent of the predicted refugia. In 14 of the 20 species, the predictions from ENM and predictions based on phylogeographic studies were significantly spatially correlated, suggesting that the two approaches to development of refugial maps are converging on a similar result. Our results confirm that ENM scenario exploration can provide a useful complement to molecular studies, offering a less subjective, spatially explicit hypothesis of past geographic patterns of distribution. PMID:17622339

Waltari, Eric; Hijmans, Robert J.; Peterson, A. Townsend; Nyari, Arpad S.; Perkins, Susan L.; Guralnick, Robert P.

2007-01-01

184

Ecologic niche modeling of *Blastomyces dermatitidis* in Wisconsin  

E-print Network

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 ...

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

2008-04-30

185

Modeling patch occupancy: Relative performance of ecologically scaled landscape indices  

Microsoft Academic Search

In fragmented landscapes, the likelihood that a species occupies a particular habitat patch is thought to be a function of\\u000a both patch area and patch isolation. Ecologically scaled landscape indices (ESLIs) combine a species’ ecological profile,\\u000a i.e., area requirements and dispersal ability, with indices of patch area and connectivity. Since their introduction, ESLIs\\u000a for area have been modified to incorporate

Carol E. Rizkalla; Jeffrey E. Moore; Robert K. Swihart

2009-01-01

186

Operations planning simulation: Model study  

NASA Technical Reports Server (NTRS)

The use of simulation modeling for the identification of system sensitivities to internal and external forces and variables is discussed. The technique provides a means of exploring alternate system procedures and processes, so that these alternatives may be considered on a mutually comparative basis permitting the selection of a mode or modes of operation which have potential advantages to the system user and the operator. These advantages are measurements is system efficiency are: (1) the ability to meet specific schedules for operations, mission or mission readiness requirements or performance standards and (2) to accomplish the objectives within cost effective limits.

1974-01-01

187

Review of three-dimensional ecological modelling related to the North Sea shelf system. Part 1: models and their results  

NASA Astrophysics Data System (ADS)

The state-of-the-art in modelling the marine ecosystem of the greater North Sea is reviewed, providing an overview especially about three-dimensional models that describe and predict how the marine ecosystem of the greater North Sea area functions and how concentrations and fluxes of biologically important elements vary in space and time, throughout the shelf and over years, in response to physical forcing. Articles with a strong concentration on modelling were selected from the available literature, and all articles around the existing “ecological modelling groups” dealing with the area of the North Sea were sorted in chronological order of their appearance in the literature. We found eleven of such groups and described their different modelling efforts. Selecting the seven three-dimensional models (NORWECOM, GHER, ECOHAM, ERSEM, ELISE, COHERENS and POL3dERSEM), we characterized the complexity of the models, by comparing the resolution in time and space, and the resolution of the trophic structure by discussing the number and kind of state variables and of the processes relating these state variables to each other. The review of biogeochemical/ecological modelling for the greater North Sea shows that important findings by model simulations have either confirmed existing knowledge derived from field work or have given new insight into the mechanisms of the functioning of the North Sea system: the temporal and spatial development and magnitude of primary production, its spreading from the coasts to the north-west over the open North Sea, its mechanisms of limitation, the functioning of the pelagic small food web and of the benthic web, the mechanisms of nutrient regeneration, the effects of riverine and atmospheric nutrient inputs causing eutrophication of coastal waters, the extent of eutrophication in the North Sea, and the budgets for nitrogen, phosphorus, and silicon. The three-dimensional ecological models of the greater North Sea have provided consistent distributions and dynamics of the lower trophic levels on their regional, annual and decadal scales which cannot be derived to this degree of coverage by observations. The state-of-the-art in validation for these models is presented in part 2

Moll, Andreas; Radach, Günther

2003-05-01

188

Model Validation with Hybrid Dynamic Simulation  

SciTech Connect

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.

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

2006-06-18

189

Modeling on an ecological food chain with recycling  

NASA Astrophysics Data System (ADS)

We propose two nutrient-phytoplankton models with instantaneous and time delayed recycling, investigate the dynamics and examine the responses to model complexities. Instead of the familiar specific uptake rate and growth rate functions, we assume only that the nutrient uptake and phytoplankton growth rate functions are positive, increasing and bounded above. We use geometrical and analytical methods to find conditions for the existence of none, one, or at most two positive steady states and analyze the stability properties of each of these equilibria. With the variation of parameters, the system may lose its stability and bifurcation may occur. We study the occurrence of Hopf bifurcation and the possibility of stability switching. Numerical simulations illustrate the analytical results and provide further insight into the dynamics of the models, biological interpretations are given.

Cai, Qinghua; Mohamad, Zakaria; Yuan, Yuan

2012-12-01

190

A modular BLSS simulation model  

NASA Technical Reports Server (NTRS)

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.

Rummel, John D.; Volk, Tyler

1987-01-01

191

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...

192

MODELING AND SIMULATING COOPERATION AND TEAMWORK  

Microsoft Academic Search

Cooperation and teamwork are aspects of human behavior that are crucial to realistic simulation of human behavior, but which have proven difficult to represent in the computer. New advances in cognitive simulation have enabled effective simulation of human behavior in individual tasks ('taskwork'), but teamwork requires still higher order cognitive abilities. The cognitive requirements for modeling and simulating cooperation and

Wayne W. Zachary; Bethlehem Pike

193

Mapping the Potential Risk of Mycetoma Infection in Sudan and South Sudan Using Ecological Niche Modeling  

E-print Network

of soil type and Acacia geographic distribution on mycetoma case distributions. Here, we map risk of mycetoma infection across Sudan and South Sudan using ecological niche modeling (ENM). For this study, records of mycetoma cases were obtained from...

Samy, Abdallah Mohammed; van de Sande, Wendy W. J.; Fahal, Ahmed Hassan; Peterson, A. Townsend

2014-10-16

194

Geographic Distribution of Chagas Disease Vectors in Brazil Based on Ecological NicheModeling  

E-print Network

risk, the geographic distribution of Brazilian triatomines was analyzed. Sixteen out of 62 Brazilian species that both occur in > 20 municipalities and present synanthropic tendencies were modeled based on their ecological niches. Panstrongylus...

Gurgel-Gonç alves, Rodrigo; Galv˜ao, Cl´ eber; Costa, Jane; Peterson, A. Townsend

2011-01-01

195

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

Microsoft Academic Search

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 \\

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

196

Special purpose simulation modeling of tower cranes  

Microsoft Academic Search

Historically, simulation tools have only been used and understood by the academic community. Special purpose simulation (SPS) techniques have introduced computer modeling to the industry, resulting in reduced model development time and a user-friendly environment. This paper describes the special purpose simulation template, which is based on the tower crane operations performed by PCL Constructors Incorporated. On-site management of the

Bradford J. A. Appleton; J. Patra; Y. Mohamed; S. AbourRizk

2002-01-01

197

Verification and validation of simulation models  

Microsoft Academic Search

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,

Jack P. C. Kleijnen

1995-01-01

198

Modeling and simulation of power electronic converters  

Microsoft Academic Search

This paper reviews some of the major approaches to modeling and simulation in power electronics, and provides references that can serve as a starting point for the extensive literature on the subject. The major focus of the paper is on averaged models of various kinds, but sampled-data models are also introduced. The importance of hierarchical modeling and simulation is emphasized

DRAGAN MAKSIMOVIC ´; ALEKSANDAR M. STANKOVIC; V. JOSEPH THOTTUVELIL; GEORGE C. VERGHESE

2001-01-01

199

Validation and verification of simulation models  

Microsoft Academic Search

ABSTRACT This paper discusses validation and verification of simulation models. The different approaches to deciding model validity are presented; how,model validation and verification 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; and a recommended,procedure is presented. 1,INTRODUCTION Simulation models are increasingly

Robert G. Sargent

1992-01-01

200

Designing for ecology : the ecological park  

E-print Network

This thesis aims to define a) what an ecological park is, and b) whether it is a new model in park design. Reference to the literature on landscape ecology is used to analyze the natural ecological merit of these parks, ...

Power, Andres M

2006-01-01

201

Mass-Balance Models for Animal Isotopic Ecology  

E-print Network

of Biology, Albuquerque, NM, USA SYNOPSIS Analysis of natural stable isotope ratios has created a methodological upheaval in animal ecology. Because the distribution of stable isotopes in organisms follows, because animal ecologists have adopted a phenomenological approach to the use of stable isotopes

Wolf, Blair O.

202

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;

203

Predicting the Geography of Species' Invasions via Ecological Niche Modeling  

Microsoft Academic Search

Species' invasions have long been regarded as enormously complex processes, so complex as to defy predictivity. Phases of this process, however, are emerging as highly predictable: the potential geographic course of an invasion can be anticipated with high precision based on the ecological niche characteristics of a species in its native geographic distributional area. This predictivity depends on the premise

A. Townsend Peterson

2003-01-01

204

Automated experimentation in ecological networks  

PubMed Central

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

2011-01-01

205

Aeroacoustic simulation for phonation modeling  

NASA Astrophysics Data System (ADS)

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.

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

2011-11-01

206

An artificial intelligence modelling approach to simulating animal\\/habitat interactions  

Microsoft Academic Search

Saarenmaa, H., Stone, N.D., Folse, L.J., Packard, J.M., Grant, W.E., Makela, M.E. and Coulson, R.N., 1988. An artificial intelligence modelling approach to simulating animal\\/habitat interactions. Ecol. Modelling, 44: 125-141. Ecological modellers have begun to recognize the potential of object-oriented program- ming techniques in structuring models. However, little has been done to take advantage of artificial intelligence's (AI) symbolic representations to

H. SAARENMAA; N. D. STONE; L. J. FOLSE; J. M. PACKARD; W. E. GRANT; M. E. MAKELA; R. N. COULSON

1988-01-01

207

An introduction to enterprise modeling and simulation  

SciTech Connect

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.

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

1996-09-01

208

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

NASA Astrophysics Data System (ADS)

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.

Gelpi-Rodriguez, Phaedra

209

Effects of Changes in Lugu Lake Water Quality on Schizothorax Yunnansis Ecological Habitat Based on HABITAT Model  

NASA Astrophysics Data System (ADS)

Schizothorax Yunnansis is an unique fish species only existing in Lugu Lake, which is located in the southwestern China. The simulation and research on Schizothorax Yunnansis habitat environment have a vital significance to protect this rare fish. With the development of the tourism industry, there bring more pressure on the environmental protection. The living environment of Schizothorax Yunnansis is destroyed seriously because the water quality is suffering the sustaining pollution of domestic sewage from the peripheral villages. This paper analyzes the relationship between water quality change and Schizothorax Yunnansis ecological habitat and evalutes Schizothorax Yunnansis's ecological habitat impact based on HABITAT model. The results show that when the TP concentration in Lugu Lake does not exceed Schizothorax Yunnansis's survival threshold, Schizothorax Yunnansis can get more nutrients and the suitable habitat area for itself is increased. Conversely, it can lead to TP toxicity in the Schizothorax Yunnansis and even death. Therefore, unsuitable habitat area for Schizothorax Yunnansis is increased. It can be seen from the results that HABITAT model can assist in ecological impact assessment studies by translating results of hydrological, water quality models into effects on the natural environment and human society.

Huang, Wei; Mynnet, Arthur

210

Verification and Validation of Simulation Model  

E-print Network

Verification and Validation of Simulation Model 1 Verification and Validation 2 #12;Verification · Examples ­ simulation model: open networks with exponential interarrival time distribution and uniform is consistent with known analytic results 5 Validation · Model should be "good enough" (subjective) · Seek

Shihada, Basem

211

COMPOSABLE SIMULATION MODELS AND THEIR FORMAL VALIDATION  

E-print Network

COMPOSABLE SIMULATION MODELS AND THEIR FORMAL VALIDATION CLAUDIA SZABO B. Eng., "POLITEHNICA, as well as the verification and validation of the composed model. Using a component- connector paradigm and simulation, shared models are reused and as- sembled in various combinations to meet different user

Teo, Yong-Meng

212

Investment simulation model in electrical utility industry  

SciTech Connect

A simulation model is presented which would provide an effective investment tool with the decision makers in dealing with uncertainty inherent in the choice of constructing a power plant. A general simulation model based upon SLAM is developed and a case study is provided to demonstrate the effectiveness of the model. 2 refs.

Park, C.S.

1980-01-01

213

A simulation model for adaptation of cotton bollworm to transgenic Bt cotton in northern China  

Microsoft Academic Search

The commercial use of transgenic cotton expressing an insecticidal protein gene from Bacillus thuringiensis (Bt) began in 1998 in northern China. Resistance management is a major concern for the sustainable use of Bt cotton. With our understanding of the cropping and ecological system in northern China , we developed a simulation model to forecast adaptation of the cotton bollworm ,

RU Li; RUI Chang

214

Construction engineering and project management II: agent-based modeling and simulation in construction  

Microsoft Academic Search

Agent-based Modeling and Simulation (ABMS) is a relatively new development that has found extensive use in areas such as social sciences, economics, biology, ecology etc. Can ABMS be effectively used in finding answers to complex construction systems? The focus of this paper is to provide some answers to this question. Initial experimentation is conducted to understand the advantages of using

Anil Sawhney; Howard H. Bashford; Kenneth D. Walsh; Ajith Rao Mulky

2003-01-01

215

Verification, validation and accreditation of simulation models  

Microsoft Academic Search

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;

Robert G. Sargent

2000-01-01

216

Validation and verification of simulation models  

Microsoft Academic Search

This paper discusses validation and verification of simulation models. The different approaches to deciding model validity are presented; how model validation and verification 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; and a recommended procedure is presented.

Robert G. Sargent

1999-01-01

217

Verification and validation of simulation models  

Microsoft Academic Search

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

Robert G. Sargent

1994-01-01

218

Validation and verification of simulation models  

Microsoft Academic Search

This paper discusses validation and verification of simulation models. The different approaches to deciding model validity are presented; how model validation and verification 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; and a recommended procedure is presented

Robert G. Sargent

1999-01-01

219

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...

220

A model intercomparison for stochastic simulation of temporal precipitation  

NASA Astrophysics Data System (ADS)

Stochastic models, based on diverse stochastic processes, have been applied in the last decades for the simulation of precipitation time series. Different models target a good reproduction of statistical properties of precipitation across a specific range of temporal scales. The choice of the statistical properties and the respective range of scales are frequently dictated by the purpose for which each model is built. Despite the large variety of stochastic precipitation modeling tools, an intercomparison has been rarely attempted. Moreover, a common practice is to validate a stochastic model only for the statistical properties for which it has been developed to perform well. It is our opinion that this practice may have negative implications, especially when stochastic models are used in hydrology as a black box. In this study we present an extensive comparison among some of the most widely applied stochastic precipitation models. Models based on point processes (e.g. Neyman-Scott rectangular pulses model, Bartlett-Lewis rectangular pulses model), Mutiplicative Random Cascades (e.g. canonical and microcanonical MRC), Markov chains, scaling processes and their combinations (e.g. Paschalis et al., 2013, Advances in Water resources) are used in order to assess their efficiency for a number of stations belonging to different climates, spanning from semiarid to wet oceanic. A complete model validation is performed, taking into account all the essential statistical properties of precipitation (e.g. probability distribution, extremes, autocorrelation, intermittency, etc.) for a wide range of temporal scales relevant for hydrological and ecological applications. The overall goal is to identify the general patterns of the strengths and weaknesses of the various modeling tools, and to provide insights for generally applicable guidelines in the model selection dependent on the specific hydrological/ecological application.

Paschalis, Athanasios; Molnar, Peter; Fatichi, Simone; Burlando, Paolo

2014-05-01

221

Theory, Modeling, and Simulation of Semiconductor Lasers  

NASA Technical Reports Server (NTRS)

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.

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

1998-01-01

222

Violent Victimization and Perpetration During Adolescence: Developmental Stage Dependent Ecological Models  

Microsoft Academic Search

Using a variant of the ecological-transactional model and developmental theories of delinquency on a nationally representative\\u000a sample of adolescents, the current study explored the ecological predictors of violent victimization, perpetration, and both\\u000a for three different developmental stages during adolescence. We examined the relative influence of individual and family characteristics,\\u000a peers, and neighborhood characteristics on the odds of experiencing violent victimization

Jennifer L. MatjaskoBelinda; Belinda L. Needham; Leslie N. GrundenAmy; Amy Feldman Farb

2010-01-01

223

Demographic and Ecological Factors in FAO Tropical Deforestation Modelling  

Microsoft Academic Search

\\u000a Tropical forests of developing countries, perceived by the public opinion in developed countries as goods to be preserved,\\u000a are essential resources to be exploited from the internal point of view. Population growth and initial economic development\\u000a requires space, and are associated with some degree of deforestation. Local ecological characteristics, which heavily condition\\u000a agricultural practices and productivity, directly influence clearance requirements.

Roberto Scotti

224

Ammonia-oxidizing bacteria: A model for molecular microbial ecology  

Microsoft Academic Search

The eutrophication of many ecosystems in recent decades has led to an increased interest in the ecology of nitrogen transformation. Chemolitho-autotrophic ammonia-oxidizing bacteria are responsible for the rate-limiting step of nitrification in a wide variety of environments, making them important in the global cycling of nitrogen. These organisms are unique in their ability to use the conversion of ammonia to

George A. Kowalchuk; John R. Stephen

2001-01-01

225

Using Species Distribution Models for Conservation Planning and Ecological Forecasting  

Microsoft Academic Search

\\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

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

226

Ecologic niche modeling and spatial patterns of disease transmission  

E-print Network

- 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... test was possible. Further exploration of this possible application of ENM methods has focused on the mysterious long-term reser- voir of the filoviruses (Ebola and Marburg viruses) by comparing African mammal distributions with those of filovirus...

Peterson, A. Townsend

2006-12-01

227

The Urban Funnel Model and the Spatially Heterogeneous Ecological Footprint  

Microsoft Academic Search

Urban ecological systems are characterized by complex interactions between the natural environment and humans at multiple\\u000a scales; for an individual urban ecosystem, the strongest interactions may occur at the local or regional spatial scale. At\\u000a the regional scale, external ecosystems produce resources that are acquired and transported by humans to urban areas, where\\u000a they are processed and consumed. The assimilation

Matthew A. Luck; G. Darrel Jenerette; Jianguo Wu; Nancy B. Grimm

2001-01-01

228

Using observation-level random effects to model overdispersion in count data in ecology and evolution  

PubMed Central

Overdispersion is common in models of count data in ecology and evolutionary biology, and can occur due to missing covariates, non-independent (aggregated) data, or an excess frequency of zeroes (zero-inflation). Accounting for overdispersion in such models is vital, as failing to do so can lead to biased parameter estimates, and false conclusions regarding hypotheses of interest. Observation-level random effects (OLRE), where each data point receives a unique level of a random effect that models the extra-Poisson variation present in the data, are commonly employed to cope with overdispersion in count data. However studies investigating the efficacy of observation-level random effects as a means to deal with overdispersion are scarce. Here I use simulations to show that in cases where overdispersion is caused by random extra-Poisson noise, or aggregation in the count data, observation-level random effects yield more accurate parameter estimates compared to when overdispersion is simply ignored. Conversely, OLRE fail to reduce bias in zero-inflated data, and in some cases increase bias at high levels of overdispersion. There was a positive relationship between the magnitude of overdispersion and the degree of bias in parameter estimates. Critically, the simulations reveal that failing to account for overdispersion in mixed models can erroneously inflate measures of explained variance (r2), which may lead to researchers overestimating the predictive power of variables of interest. This work suggests use of observation-level random effects provides a simple and robust means to account for overdispersion in count data, but also that their ability to minimise bias is not uniform across all types of overdispersion and must be applied judiciously. PMID:25320683

2014-01-01

229

Ecological Modelling 220 (2009) 24152426 Contents lists available at ScienceDirect  

E-print Network

Modelling journal homepage: www.elsevier.com/locate/ecolmodel Spatio-temporal dissolved oxygen dynamics Mathematical modelling Parameter estimation Dissolved oxygen dynamics a b s t r a c t This paper models the dissolved oxygen (DO) dynamics in the Orbetello lagoon as a function of the physico-chemical and ecological

230

An Ecological Model of Developing Researcher Competence: The Case of Software Technology in Doctoral Research  

ERIC Educational Resources Information Center

This paper presents an ecological model of developing researcher competence, with a particular focus on doctoral students' use of research software. The model extends on theoretical work done by Young et al. ("Instructional Science 30"(1): 47-63, 2002), modelling the intentional dynamics of technological learning contexts. The development of the…

Stelma, Juup

2011-01-01

231

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

ERIC Educational Resources Information Center

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…

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

2014-01-01

232

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

233

Cognitive niches: an ecological model of strategy selection.  

PubMed

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

Marewski, Julian N; Schooler, Lael J

2011-07-01

234

Integrating human and natural systems in community psychology: an ecological model of stewardship behavior.  

PubMed

Community psychology (CP) research on the natural environment lacks a theoretical framework for analyzing the complex relationship between human systems and the natural world. We introduce other academic fields concerned with the interactions between humans and the natural environment, including environmental sociology and coupled human and natural systems. To demonstrate how the natural environment can be included within CP's ecological framework, we propose an ecological model of urban forest stewardship action. Although ecological models of behavior in CP have previously modeled health behaviors, we argue that these frameworks are also applicable to actions that positively influence the natural environment. We chose the environmental action of urban forest stewardship because cities across the United States are planting millions of trees and increased citizen participation in urban tree planting and stewardship will be needed to sustain the benefits provided by urban trees. We used the framework of an ecological model of behavior to illustrate multiple levels of factors that may promote or hinder involvement in urban forest stewardship actions. The implications of our model for the development of multi-level ecological interventions to foster stewardship actions are discussed, as well as directions for future research to further test and refine the model. PMID:22722897

Moskell, Christine; Allred, Shorna Broussard

2013-03-01

235

A Generic Multibody Parachute Simulation Model  

NASA Technical Reports Server (NTRS)

Flight simulation of dynamic atmospheric vehicles with parachute systems is a complex task that is not easily modeled in many simulation frameworks. In the past, the performance of vehicles with parachutes was analyzed by simulations dedicated to parachute operations and were generally not used for any other portion of the vehicle flight trajectory. This approach required multiple simulation resources to completely analyze the performance of the vehicle. Recently, improved software engineering practices and increased computational power have allowed a single simulation to model the entire flight profile of a vehicle employing a parachute.

Neuhaus, Jason Richard; Kenney, Patrick Sean

2006-01-01

236

Model Validation with Hybrid Dynamic Simulation  

SciTech Connect

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.

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

2006-06-22

237

An advanced modelling tool for simulating complex river systems.  

PubMed

The present paper describes MOHID River Network (MRN), a 1D hydrodynamic model for river networks as part of MOHID Water Modelling System, which is a modular system for the simulation of water bodies (hydrodynamics and water constituents). MRN is capable of simulating water quality in the aquatic and benthic phase and its development was especially focused on the reproduction of processes occurring in temporary river networks (flush events, pools formation, and transmission losses). Further, unlike many other models, it allows the quantification of settled materials at the channel bed also over periods when the river falls dry. These features are very important to secure mass conservation in highly varying flows of temporary rivers. The water quality models existing in MOHID are base on well-known ecological models, such as WASP and ERSEM, the latter allowing explicit parameterization of C, N, P, Si, and O cycles. MRN can be coupled to the basin model, MOHID Land, with computes runoff and porous media transport, allowing for the dynamic exchange of water and materials between the river and surroundings, or it can be used as a standalone model, receiving discharges at any specified nodes (ASCII files of time series with arbitrary time step). These features account for spatial gradients in precipitation which can be significant in Mediterranean-like basins. An interface has been already developed for SWAT basin model. PMID:19215966

Trancoso, Ana Rosa; Braunschweig, Frank; Chambel Leitão, Pedro; Obermann, Matthias; Neves, Ramiro

2009-04-01

238

Model validation with hybrid dynamic simulation  

Microsoft Academic Search

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

Zhenyu Huang; M. Kosterev; Ross T. Guttromson; Tony B. Nguyen

2006-01-01

239

Verification and validation of simulation models  

Microsoft Academic Search

In this paper we discuss verification and validation of simulation models. Four different approaches to deciding model validity are described, a graphical paradigm that relates verification and validation to the model development process is presented, and various validation techniques are defined. Conceptual model validity, model verification, operational validity, and data validity are discussed and a way to document results is

Robert G. Sargent

2011-01-01

240

Verification and validation of simulation models  

Microsoft Academic Search

In this paper we discuss verification and validation of simulation models. Four different approaches to deciding model validity are described; two different paradigms that relate verification and validation to the model development process are presented; various validation techniques are defined; conceptual model validity, model verification, operational validity, and data validity are discussed; a way to document results is given; a

Robert G. Sargent

2010-01-01

241

Verification and validation of simulation models  

Microsoft Academic Search

In this paper we discuss verification and validation of simulation models. Four different approaches to deciding model validity are described; two different paradigms that relate verification and validation to the model development process are presented; various validation techniques are defined; conceptual model validity, model verification, operational validity, and data validity are discussed; a way to document results is given; a

Robert G. Sargent

2005-01-01

242

Validation and Verification of Simulation Models  

Microsoft Academic Search

In this paper we discuss validation and verification of simulation models. Four different approaches to deciding model validity are described; two different paradigms that relate validation and verification to the model development process are presented; various validation techniques are defined; conceptual model validity, model verification, operational validity, and data validity are discussed; a way to document results is given; a

Robert G. Sargent

2004-01-01

243

Verification and validation of simulation models  

Microsoft Academic Search

In this paper we discuss verification and validation of simulation models. Four different approaches to deciding model validity are described; two different paradigms that relate verification and validation to the model development process are presented; various validation techniques are defined; conceptual model validity, model verification, operational validity, and data validity are discussed; a way to document results is given; a

Robert G. Sargent

2007-01-01

244

Verification and validation of simulation models  

Microsoft Academic Search

In this paper we discuss verification and validation of simulation models. Four different approaches to deciding model validity are described; two different paradigms that relate verification and validation to the model development process are presented; various validation techniques are defined; conceptual model validity, model verification, operational validity, and data validity are discussed; a way to document results is given; a

Robert G. Sargent

2003-01-01

245

Computational Modeling and Simulation of Infectious Diseases  

E-print Network

Computational Modeling and Simulation of Infectious Diseases May 21­July 27, 2012 Receive a 10-week of Public Health Models of Infectious Disease Agent Study (MIDAS) National Center of Excellence #12;

Sibille, Etienne

246

VHDL simulation with access to transistor models  

NASA Technical Reports Server (NTRS)

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.

Gibson, J.

1991-01-01

247

Carbon sequestration by patch fertilization: A comprehensive assessment using coupled physical-ecological-biogeochemical models  

SciTech Connect

This final report summarizes research undertaken collaboratively between Princeton University, the NOAA Geophysical Fluid Dynamics Laboratory on the Princeton University campus, the State University of New York at Stony Brook, and the University of California, Los Angeles between September 1, 2000, and November 30, 2006, to do fundamental research on ocean iron fertilization as a means to enhance the net oceanic uptake of CO2 from the atmosphere. The approach we proposed was to develop and apply a suite of coupled physical-ecological-biogeochemical models in order to (i) determine to what extent enhanced carbon fixation from iron fertilization will lead to an increase in the oceanic uptake of atmospheric CO2 and how long this carbon will remain sequestered (efficiency), and (ii) examine the changes in ocean ecology and natural biogeochemical cycles resulting from iron fertilization (consequences). The award was funded in two separate three-year installments: • September 1, 2000 to November 30, 2003, for a project entitled “Ocean carbon sequestration by fertilization: An integrated biogeochemical assessment.” A final report was submitted for this at the end of 2003 and is included here as Appendix 1. • December 1, 2003 to November 30, 2006, for a follow-on project under the same grant number entitled “Carbon sequestration by patch fertilization: A comprehensive assessment using coupled physical-ecological-biogeochemical models.” This report focuses primarily on the progress we made during the second period of funding subsequent to the work reported on in Appendix 1. When we began this project, we were thinking almost exclusively in terms of long-term fertilization over large regions of the ocean such as the Southern Ocean, with much of our focus being on how ocean circulation and biogeochemical cycling would interact to control the response to a given fertilization scenario. Our research on these types of scenarios, which was carried out largely during the first three years of our project, led to several major new insights on the interaction between ocean biogeochemistry and circulation. This work, which is described in the following Section II on “Large scale fertilization,” has continued to appear in the literature over the past few years, including two high visibility papers in Nature. Early on in the first three years of our project, it became clear that small "patch-scale" fertilizations over limited regions of order 100 km diameter were much more likely than large scale fertilization, and we carried out a series of idealized patch fertilization simulations reported on in Gnanadesikan et al. (2003). Based on this paper and other results we had obtained by the end of our first three-year grant, we identified a number of important issues that needed to be addressed in the second three-year period of this grant. Section III on “patch fertilization” discusses the major findings of this phase of our research, which is described in two major manuscripts that will be submitted for publication in the near future. This research makes use of new more realistic ocean ecosystem and iron cycling models than our first paper on this topic. We have several major new insights into what controls the efficiency of iron fertilization in the ocean. Section IV on “model development” summarizes a set of papers describing the progress that we made on improving the ecosystem models we use for our iron fertilization simulations.

Jorge L. Sarmiento - Princeton PI, Anand Gnanadesikan - Princeton Co-I, Nicolas Gruber - UCLA PI, Xin Jin - UCLA PostDoc, Robert Armstrong - SUNY /Stony Brook Consultant

2007-06-21

248

OCAM - A CELSS modeling tool: Description and results. [Object-oriented Controlled Ecological Life Support System Analysis and Modeling  

NASA Technical Reports Server (NTRS)

Controlled Ecological Life Support System (CELSS) technology is critical to the Space Exploration Initiative. NASA's Kennedy Space Center has been performing CELSS research for several years, developing data related to CELSS design. We have developed OCAM (Object-oriented CELSS Analysis and Modeling), a CELSS modeling tool, and have used this tool to evaluate CELSS concepts, using this data. In using OCAM, a CELSS is broken down into components, and each component is modeled as a combination of containers, converters, and gates which store, process, and exchange carbon, hydrogen, and oxygen on a daily basis. Multiple crops and plant types can be simulated. Resource recovery options modeled include combustion, leaching, enzyme treatment, aerobic or anaerobic digestion, and mushroom and fish growth. Results include printouts and time-history graphs of total system mass, biomass, carbon dioxide, and oxygen quantities; energy consumption; and manpower requirements. The contributions of mass, energy, and manpower to system cost have been analyzed to compare configurations and determine appropriate research directions.

Drysdale, Alan; Thomas, Mark; Fresa, Mark; Wheeler, Ray

1992-01-01

249

Fast Simulation of Facilitated Spin Models  

NASA Astrophysics Data System (ADS)

We show how to apply the absorbing Markov chain Monte Carlo algorithm of Novotny to simulate kinetically constrained models of glasses. In detail we consider the East model in one dimension. We investigate how to maximize the efficiency of the algorithms, and show that simulation times can be improved on standard continuous time Monte Carlo by several orders of magnitude. We discuss how the method can be applied to other kinetically constrained models with specific focus on the 2-spin facilitated FA model.

Ashton, D. J.; Hedges, L. O.; Garrahan, J. P.

2006-05-01

250

Right model, wrong prediction: Model-free vs Mechanistic forecasting for nonlinear ecological systems  

NASA Astrophysics Data System (ADS)

As environmental time series have grown, and computer-intensive statistical methods have become more convenient, fitting mechanistic models that incorporate both process and observation error (i.e. state-space models) has become increasingly popular. It has been suggested that such models are more robust to noise due to their inclusion of a process-error term, however their out-of-sample forecast ability remains largely untested. Therefore, it is important to determine how various forecasting strategies perform under realistic levels of noise and forcing. We compared the forecast accuracy of a model-free forecasting approach based on nonlinear state-space reconstruction (SSR) against a suite of mechanistic models fit to their own time series with realistic levels of noise added. To further favor the mechanistic approach, these models were fit using a Bayesian adaptive MCMC algorithm actually initiated on the correct parameter values. Surprisingly, we found that the SSR forecasts were more accurate than the correct mechanistic models despite being fit to only one time series of a multivariate system. This was true for four different ecological models, and for experimental data from a series of flour beetle experiments. Our results suggest that for forecasting real ecosystems, where the correct model is never known, a robust model-free approach such as SSR may be a more practical alternative to complex fitted models containing many free parameters.

Perretti, C.; Munch, S. B.; Deyle, E. R.; Ye, H.; Sugihara, G.

2012-12-01

251

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

E-print Network

from data. This is in contrast to methods like neural net- works, which most often produce black and phosphorus) and the biomass of zooplankton (which feeds on phyto- plankton). The modelling formalism most

Dzeroski, Saso

252

Empirical analysis in software process simulation modeling  

Microsoft Academic Search

Software process simulation modeling is increasingly being used to address a variety of issues from the strategic management of software development, to supporting process improvements, to software project management training. The scope of software process simulation applications ranges from narrow focused portions of the life cycle to longer-term product evolutionary models with broad organizational impacts. This paper discusses some of

David M. Raffo; Marc I. Kellner

2000-01-01

253

Computer simulations and physical modelling of erosion  

E-print Network

particle hydrodynamics (SPH). Navier-Stokes on voxel grid. · Terrain development: layered height field · initial SPH model and simulations · visit to Brazil 9 / 10 #12;Future · multiple layers of soil. · sandComputer simulations and physical modelling of erosion C.S. Stuetzle, J. Gross, Z. Chen, B. Cutler

Franklin, W. Randolph

254

Monte Carlo Simulation of Interacting Electron Models  

E-print Network

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

Robinson, Robert W.

255

Modeling and simulation of friction  

Microsoft Academic Search

Two new models for 'slip-stick' friction are presented. One, called the 'bristle model,' is an approximation designed to capture the physical phenomenon of sticking. This model is relatively inefficient numerically. The other model, called the 'reset integrator model,' does not capture the details for the sticking phenomenon, but is numerically efficient and exhibits behavior similar to the model proposed by

David A. Haessig; Bernard Friedland

1991-01-01

256

Modeling the growth dynamics of four candidate crops for Controlled Ecological Life Support Systems (CELSS)  

NASA Technical Reports Server (NTRS)

The production of food for human life support for advanced space missions will require the management of many different crops. The research to design these food production capabilities along with the waste management to recycle human metabolic wastes and inedible plant components are parts of Controlled Ecological Life Support Systems (CELSS). Since complete operating CELSS were not yet built, a useful adjunct to the research developing the various pieces of a CELSS are system simulation models that can examine what is currently known about the possible assembly of subsystems into a full CELSS. The growth dynamics of four crops (wheat, soybeans, potatoes, and lettuce) are examined for their general similarities and differences within the context of their important effects upon the dynamics of the gases, liquids, and solids in the CELSS. Data for the four crops currently under active research in the CELSS program using high-production hydroponics are presented. Two differential equations are developed and applied to the general characteristics of each crop growth pattern. Model parameters are determined by closely approximating each crop's data.

Volk, Tyler

1987-01-01

257

Modeling and simulation of reactive distillation operations  

SciTech Connect

Important aspects related to modeling and simulation of reactive distillation processes are presented. Reactive distillation processes are system specific and are subject to the sensitivity of the model parameters. The sensitive model parameters have been identified as those belonging to the models describing the physical and/or chemical equilibrium of the reactive system. The influence of the sensitive model parameters on simulation/design is highlighted through a systematic analysis of the models typically employed for steady-state and dynamic simulation of reactive distillation operations. For reliable and consistent simulation and design of reactive distillation operations, a necessary first step is a systematic analysis of the model parameter and the design/operational variables. Validated numerical results from test problems involving two reactive systems are presented.

Pilavachi, P.A. [Univ. Libre de Bruxelles, Brussels (Belgium). Faculty of Applied Sciences] [Univ. Libre de Bruxelles, Brussels (Belgium). Faculty of Applied Sciences; Schenk, M.; Perez-Cisneros, E.; Gani, R. [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Chemical Engineering] [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Chemical Engineering

1997-08-01

258

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

NASA Astrophysics Data System (ADS)

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.

Hartwig, Melanie; Borchardt, Dietrich

2010-05-01

259

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

ERIC Educational Resources Information Center

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…

Hutzler, Yeshayahu

2007-01-01

260

Contextualizing rape: Reviewing sequelae and proposing a culturally inclusive ecological model of sexual assault recovery  

Microsoft Academic Search

Consistent evidence demonstrates that many women who encounter the trauma of rape experience a range of both acute reactions and chronic psychological sequelae. This article reviews both the short- and long-term psychological adjustment issues associated with rape. In addition, we propose a culturally inclusive ecological model of sexual assault recovery (CIEMSAR), which integrates and extends existing models to better examine

Helen A. Neville; Mary J. Heppner

1999-01-01

261

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

E-print Network

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

Silander Jr., John A.

262

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...

263

Automated quality assurance checks on model structure in ecological risk assessments  

Microsoft Academic Search

A major criticism routinely leveled against probabilistic risk assessments of putative ecological impacts is that there has been insufficient validation of the model employed in the assessment. The only complete solution to this problem would involve concentrated scientific effort to test and validate the model, which is generally beyond the scope of the risk assessment effort. However, there are several

Scott Ferson

1996-01-01

264

Forest Productivity and Diversity: Using Ecological Theory and Landscape Models to Guide Sustainable Forest Management  

SciTech Connect

Sustainable forest management requires maintaining or increasing ecosystem productivity, while preserving or restoring natural levels of biodiversity. Application of general concepts from ecological theory, along with use of mechanistic, landscape-based computer models, can contribute to the successful achievement of both of these objectives. Ecological theories based on the energetics and dynamics of populations can be used to predict the general distribution of individual species, the diversity of different types of species, ecosystem process rates and pool sizes, and patterns of spatial and temporal heterogeneity over a broad range of environmental conditions. This approach requires subdivision of total biodiversity into functional types of organisms, primarily because different types of organisms respond very differently to the spatial and temporal variation of environmental conditions on landscapes. The diversity of species of the same functional type (particularly among plants) tends to be highest at relatively low levels of net primary productivity, while the total number of different functional types (particularly among animals) tends to be highest at high levels of productivity (e.g., site index or potential net primary productivity). In general, the diversity of animals at higher trophic levels (e.g., predators) reaches its maximum at much higher levels of productivity than the diversity of lower trophic levels (e.g., plants). This means that a single environment cannot support high diversity of all types of organisms. Within the framework of the general patterns described above, the distributions, population dynamics, and diversity of organisms in specific regions can be predicted more precisely using a combination of computer simulation models and GIS data based on satellite information and ground surveys. Biophysical models that use information on soil properties, climate, and hydrology have been developed to predict how the abundance and spatial distribution of various plants and animals. These models can be, used to predict the patterns of forest type and structure that develop in response to variation in productivity and disturbance across complex landscapes, as well as species diversity and the distribution and population fluctuations of threatened species in specific regions.

Huston, M.A.

1998-11-01

265

Study on ecological impact evaluation for land consolidation based on cloud model: a case study of Miaotan town  

Microsoft Academic Search

Combining the basic theory of cloud model and the process of ecological impact evaluation for land consolidation, the author constructs the rule of ecological impact evaluation and the cloud models of the antecedent and the consequent, by translating the uncertain factor conditions into quantitative values with the uncertain illation based on cloud model, computes the evaluation factor scores and comprehensive

Yao-lin Liu; Min Fan; Xiao-yu Yang; Hui Liu

2008-01-01

266

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

E-print Network

Virtual Epidemics ­ Ecological Modeling on a Parallel Machine Bill Maniatty 1 , Boleslaw Szymanski we discuss the implementation of such spatially explicit models of epidemics on massively parallel computers. We have designed and implemented two basic but ecologically significant models for epidemic

Maniatty, William A.

267

Hierarchy Theory in Sociology, Ecology, and Resource Management: A Conceptual Model for Natural Resource or Environmental Sociology and Socioecological Systems  

Microsoft Academic Search

This article argues that hierarchy theory can be used as a conceptual bridge to facilitate analysis of socioecological systems (SES). An SES model is proposed based on a synthesis of structuration theory in sociology and hierarchy theory in ecology. The model is process rather than component based by relating institutional processes with ecological processes at multiple scales. The model also

WILLIAM A. WARREN

2005-01-01

268

MOSFET substrate current model for circuit simulation  

Microsoft Academic Search

A simple, accurate MOSFET substrate current model suitable for a circuit simulator is presented. The effect of substrate bias on substrate current is modeled without introducing additional parameters. The accuracy of this model is demonstrated by its ability to fit the experimental data for both standard and LDD devices with average errors of less than 6%. The new model is

Narain D. Arora; Mahesh S. Sharma

1991-01-01

269

Simulation model for aircraft line maintenance planning  

Microsoft Academic Search

This paper reports results of research that developed a computerized simulation model for the aircraft line maintenance department in Continental Airlines. The original AUTOMOD model that was created duplicated the maintenance operations at Continental's major maintenance station at Newark. Modeling the day-to-day maintenance activities lead to the development of enhanced staffing models and a better understanding of resource requirements on

P. Gupta; M. Bazargan; R. N. McGrath

2003-01-01

270

Qualitative Simulation Model for Software Engineering Process  

Microsoft Academic Search

Software process simulation models hold out the promise of improving project planning and control. However, quantitative models require a very detailed understanding of the software process. In particular, process knowledge needs to be represented quantitatively which requires extensive, reliable software project data. When such data is lacking, quantitative models must impose severe constraints, restricting the value of the models. In

He Zhang; Ming Huo; Barbara Kitchenham; D. Ross Jeffery

2006-01-01

271

Computational modeling for eco engineering: Making the connections between engineering and ecology (Invited)  

NASA Astrophysics Data System (ADS)

Ecological engineering, or eco engineering, is an emerging field in the study of integrating ecology and engineering, concerned with the design, monitoring, and construction of ecosystems. According to Mitsch (1996) 'the design of sustainable ecosystems intends to integrate human society with its natural environment for the benefit of both'. Eco engineering emerged as a new idea in the early 1960s, and the concept has seen refinement since then. As a commonly practiced field of engineering it is relatively novel. Howard Odum (1963) and others first introduced it as 'utilizing natural energy sources as the predominant input to manipulate and control environmental systems'. Mtisch and Jorgensen (1989) were the first to define eco engineering, to provide eco engineering principles and conceptual eco engineering models. Later they refined the definition and increased the number of principles. They suggested that the goals of eco engineering are: a) the restoration of ecosystems that have been substantially disturbed by human activities such as environmental pollution or land disturbance, and b) the development of new sustainable ecosystems that have both human and ecological values. Here a more detailed overview of eco engineering is provided, particularly with regard to how engineers and ecologists are utilizing multi-dimensional computational models to link ecology and engineering, resulting in increasingly successful project implementation. Descriptions are provided pertaining to 1-, 2- and 3-dimensional hydrodynamic models and their use at small- and large-scale applications. A range of conceptual models that have been developed to aid the in the creation of linkages between ecology and engineering are discussed. Finally, several case studies that link ecology and engineering via computational modeling are provided. These studies include localized stream rehabilitation, spawning gravel enhancement on a large river system, and watershed-wide floodplain modeling of the Sacramento River Valley.

Bowles, C.

2013-12-01

272

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

USGS Publications Warehouse

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.

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

2010-01-01

273

Simulation of geological models using multipoint histogram  

SciTech Connect

Simulated annealing optimization technique was used to simulate geological models. After comparing one-point perturbation scheme with two-point swapping scheme, and the Metropolis algorithm with the greedy algorithm, an optimized combination of simulated annealing schedule is presented. The two-dimensional correlation coefficient matrix is introduced to determine a unit configuration which can represent essential features of a geological model. The proposed simulated annealing technique can be used to reproduce the characteristics of a geological model based on multipoint histogram which can be obtained by using a unit configuration. Various geological vertical cross sections and horizontal slices based on field data are used to validate this new technique. Simulated results confirm that one-point perturbation scheme with the Metropolis algorithm provides the best combination to capture the essential features of a geological model. Further, the two-dimensional correlation coefficient matrix provides a technique to choose a priori unit configuration for multipoint histogram, which captures the geological characteristics adequately.

Qiu, W.Y.; Kelkar, M.G. [SPE, Richardson, TX (United States); [Univ. of Tulsa, OK (United States)

1995-12-31

274

Protein Simulation Data in the Relational Model  

PubMed Central

High performance computing is leading to unprecedented volumes of data. Relational databases offer a robust and scalable model for storing and analyzing scientific data. However, these features do not come without a cost—significant design effort is required to build a functional and efficient repository. Modeling protein simulation data in a relational database presents several challenges: the data captured from individual simulations are large, multi-dimensional, and must integrate with both simulation software and external data sites. Here we present the dimensional design and relational implementation of a comprehensive data warehouse for storing and analyzing molecular dynamics simulations using SQL Server. PMID:23204646

Simms, Andrew M.; Daggett, Valerie

2011-01-01

275

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

PubMed Central

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

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

2012-01-01

276

Modeling and simulation of luminescence detection platforms  

Microsoft Academic Search

Motivated by the design of an integrated CMOS-based detection platform, a simulation model for CCD and CMOS imager-based luminescence detection systems is developed. The model comprises four parts. The first portion models the process of photon flux generation from luminescence probes using ATP-based and luciferase label-based assay kinetics. An optics simulator is then used to compute the incident photon flux

Khaled Salama; Helmy Eltoukhy; Arjang Hassibi; Abbas El Gamal

2004-01-01

277

Ecological model of occupational stress. Application to urban firefighters.  

PubMed

1. Multiple individual and organizational barriers make it difficult for occupational health nurses and other providers to understand and handle stress in the workplace. 2. Recent research suggests adverse health effects resulting from occupational stress are more related to the context or conditions of work than workers' characteristics. 3. The ecological approach described in this article provides a means to examine the context in which stress occurs through an analysis of four levels of influence. The levels of influence include the microsystem, the organizational system, the peri-organizational system, and the extra-organizational system. 4. Through a careful analysis using this approach, an identification of the entire spectrum of factors contributing to the occurrence of workplace stressors can be identified, and more effective interventions addressing existing and potential problems related to occupational stress can be developed. PMID:11760257

Salazar, M K; Beaton, R

2000-10-01

278

Predicting the current and future potential distributions of lymphatic filariasis in Africa using maximum entropy ecological niche modelling.  

PubMed

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

Slater, Hannah; Michael, Edwin

2012-01-01

279

Software-Engineering Process Simulation (SEPS) model  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

280

SIMULATION MODELING OF GASTROINTESTINAL ABSORPTION  

EPA Science Inventory

Mathematical dosimetry models incorporate mechanistic determinants of chemical disposition in a living organism to describe relationships between exposure concentration and the internal dose needed for PBPK models and human health risk assessment. Because they rely on determini...

281

An Open Source Simulation Model for Soil and Sediment Bioturbation  

PubMed Central

Bioturbation is one of the most widespread forms of ecological engineering and has significant implications for the structure and functioning of ecosystems, yet our understanding of the processes involved in biotic mixing remains incomplete. One reason is that, despite their value and utility, most mathematical models currently applied to bioturbation data tend to neglect aspects of the natural complexity of bioturbation in favour of mathematical simplicity. At the same time, the abstract nature of these approaches limits the application of such models to a limited range of users. Here, we contend that a movement towards process-based modelling can improve both the representation of the mechanistic basis of bioturbation and the intuitiveness of modelling approaches. In support of this initiative, we present an open source modelling framework that explicitly simulates particle displacement and a worked example to facilitate application and further development. The framework combines the advantages of rule-based lattice models with the application of parameterisable probability density functions to generate mixing on the lattice. Model parameters can be fitted by experimental data and describe particle displacement at the spatial and temporal scales at which bioturbation data is routinely collected. By using the same model structure across species, but generating species-specific parameters, a generic understanding of species-specific bioturbation behaviour can be achieved. An application to a case study and comparison with a commonly used model attest the predictive power of the approach. PMID:22162997

Schiffers, Katja; Teal, Lorna Rachel; Travis, Justin Mark John; Solan, Martin

2011-01-01

282

Mechanism simulation with Working Model  

Microsoft Academic Search

Kinematics is a study of motion and force of linkages, gear trains and cams. To many students, visualizing the motion of a mechanism is very challenging. Physical models can be built to illustrate the motion, and modular models using Tinkertoy or Lego are also effective. However, the link lengths of these models are fixed to some extent, and the physical

Shih-Liang Wang

1996-01-01

283

The ecological footprint: a non-monetary metric of human consumption applied to North America  

Microsoft Academic Search

This paper employs ecological footprint analysis as a potential non-monetary metric of human consumption and ecological productivity in a simulation-modeling framework, applied to North America. The ecological footprint provides an indirect basis for considering the long-term ecological risk and sustainability of human settlements, regions or, in this case, a continent. We examine several scenarios for human consumption, ecological productivity and

Maged Senbel; Timothy McDaniels; Hadi Dowlatabadi

2003-01-01

284

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

E-print Network

agent models (predator-prey systems, battlefield simulations, robot tanks, robot soccer), planetary planted at the centre of the image is gradually grown by releasing "walker" particles around about it. The walkers diffuse randomly and attach themselves to the growing aggregate. This cluster was grown

Hawick, Ken

285

Modeling Physics with Easy Java Simulations  

NSDL National Science Digital Library

The paper Modeling Physics with Easy Java Simulations describes the use of the Easy Java Simulations (Ejs) modeling and authoring tool and shows how this tool can be used to teach mechanics concepts using computer modeling. Although the modeling method can be used without computers, the use of computers allows students to study problems that are difficult and time consuming, to visualize their results, and to communicate their results with others. The combination of computer modeling with theory and experiment can achieve insight and understanding that cannot be achieved with only one approach. Journal article available from http://scitation.aip.org/tpt/

Christian, Wolfgang; Franciscouembre

2008-05-30

286

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

PubMed

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

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

2014-02-15

287

An ecological-physical coupled model applied to Station Papa  

Microsoft Academic Search

A vertical one-dimensional ecosystem model was constructed and applied to Station Papa. The model has seven compartments (phytoplankton, nitrate, ammonium, zooplankton, particulate organic matters, dissolved organic matters, dissolved oxygen) and was coupled with a mixed layer model for calculating diffusion coefficient which appears in the governing equations. The mixed layer model was driven by SST, SSS data observed at Station

Michio Kawamiya; Michio J. Kishi; Yasuhiro Yamanaka; Nobuo Suginohara

1995-01-01

288

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

PubMed

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

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

2012-08-01

289

Modelling and Simulation of Pedestrian Behaviours  

Microsoft Academic Search

The modelling and simulation of autonomous pedestrians has important applications in real-time crowd and crisis simulations. With the increase in processing powers and dedicated graphics cards, more processing powers can now be allocated for the generation of realistic behaviours for individuals within the crowd. We have proposed a representation for autonomous agents that is aimed to generate some human-like behaviours.

W. L. Koh; Lin Lin; Suiping Zhou

2008-01-01

290

Compressible Homogeneous Shear: Simulation and Modeling \\Lambda  

E-print Network

Compressible Homogeneous Shear: Simulation and Modeling \\Lambda S. Sarkar, G. Erlebacher, and M numerical simulation of homogeneous shear flow. A primary observation is that the growth of the turbulent and Engineering (ICASE), NASA Langley Research Center, Hampton, VA 23665. i #12; 1 Introduction Homogeneous

Erlebacher, Gordon

291

Consequence modeling using the fire dynamics simulator  

Microsoft Academic Search

The use of Computational Fluid Dynamics (CFD) and in particular Large Eddy Simulation (LES) codes to model fires provides an efficient tool for the prediction of large-scale effects that include plume characteristics, combustion product dispersion, and heat effects to adjacent objects. This paper illustrates the strengths of the Fire Dynamics Simulator (FDS), an LES code developed by the National Institute

Noah L. Ryder; Jason A. Sutula; Christopher F. Schemel; Andrew J. Hamer; Vincent Van Brunt

2004-01-01

292

Enterprise Modeling and Simulation Within Enterprise Engineering  

Microsoft Academic Search

One of the strengths of simulation as a method of inquiry and tool of study is its ability to provide a platform for breakthrough ideas in emerging interdisciplinary fields. In this article, the author defines enterprise engineering as an interdisciplinary field and discusses the role of modeling and simulation and its potential in enterprise engineering. In particular, the author discusses

Joseph Barjis

2011-01-01

293

Observations and simulations improve space weather models  

E-print Network

- 1 - Observations and simulations improve space weather models June 25, 2014 Los Alamos with fast-moving particles and a space weather system that varies in response to incoming energy computer simulations of the space weather that can affect vital technology, communication and navigation

294

Maintenance Personnel Performance Simulation (MAPPS) model  

SciTech Connect

A stochastic computer model for simulating the actions and behavior of nuclear power plant maintenance personnel is described. The model considers personnel, environmental, and motivational variables to yield predictions of maintenance performance quality and time to perform. The mode has been fully developed and sensitivity tested. Additional evaluation of the model is now taking place.

Siegel, A.I.; Bartter, W.D.; Wolf, J.J.; Knee, H.E.; Haas, P.M.

1984-01-01

295

On Computer Simulation Models of RSW Process  

Microsoft Academic Search

Due to its high complicacy and transitoriness and closeness, resistance spot welding (RSW), which is widely employed as a major sheet metal joining technology in automotive industry, has attracted specific attentions for computer simulations since last century. In this paper, four major RSW numerical models, namely thermal model, electro-thermal model, electro-thermo-mechanical model and electro-thermal model with fluid flow field, are

Haining Zheng; Yongbing Li

2009-01-01

296

Transportation Analysis, Modeling, and Simulation (TAMS) Application  

E-print Network

Transportation Analysis, Modeling, and Simulation (TAMS) Application Center for Transportation Passenger Flows Supply Chain Efficiency Transportation: Energy Environment Safety Security Vehicle Technologies T he Center for Transportation Analysis (CTA) TAMS application is a web-based tool that supports

297

A Simulation To Model Exponential Growth.  

ERIC Educational Resources Information Center

Describes a simulation using dice-tossing students in a population cluster to model the growth of cancer cells. This growth is recorded in a scatterplot and compared to an exponential function graph. (KHR)

Appelbaum, Elizabeth Berman

2000-01-01

298

Modelling Reactive and Proactive Behaviour in Simulation  

E-print Network

This research investigated the simulation model behaviour of a traditional and combined discrete event as well as agent based simulation models when modelling human reactive and proactive behaviour in human centric complex systems. A departmental store was chosen as human centric complex case study where the operation system of a fitting room in WomensWear department was investigated. We have looked at ways to determine the efficiency of new management policies for the fitting room operation through simulating the reactive and proactive behaviour of staff towards customers. Once development of the simulation models and their verification had been done, we carried out a validation experiment in the form of a sensitivity analysis. Subsequently, we executed a statistical analysis where the mixed reactive and proactive behaviour experimental results were compared with some reactive experimental results from previously published works. Generally, this case study discovered that simple proactive individual behaviou...

Majid, Mazlina Abdul; Aickelin, Uwe

2010-01-01

299

MODELING CONCEPTS FOR BMP/LID SIMULATION  

EPA Science Inventory

Enhancement of simulation options for stormwater best management practices (BMPs) and hydrologic source control is discussed in the context of the EPA Storm Water Management Model (SWMM). Options for improvement of various BMP representations are presented, with emphasis on inco...

300

Aggregate calibration of microscopic traffic simulation models  

E-print Network

The problem of calibration of microscopic simulation models with aggregate data has received significant attention in recent years. But day-to-day variability in inputs such as travel demand has not been considered. In ...

Mahanti, Bhanu Prasad, 1981-

2004-01-01

301

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

302

Modeling and simulation of dielectric elastomer actuators  

NASA Astrophysics Data System (ADS)

Dielectric elastomers are used as base material for so-called electroactive polymer (EAP) actuators. A procedure and a specific constitutive model (for the acrylic elastomer VHB 4910) are presented in this work for finite element modeling and simulation of dielectric elastomer actuators of general shape and set-up. The Yeoh strain energy potential and the Prony series are used for describing the large strain time-dependent mechanical response of the dielectric elastomer. Material parameters were determined from uniaxial experiments (relaxation tests and tensile tests). Thereby the inverse problem was solved using iterative finite element calculations. A pre-strained circular actuator was built and activated with a predefined voltage. A three-dimensional finite element model of the circular actuator was created and the electromechanical activation process simulated. Simulation and actual measurements agree to a great extent, thus leading to a validation of both the constitutive model and the actuator simulation procedure proposed in this work.

Wissler, Michael; Mazza, Edoardo

2005-12-01

303

Fuzzy Modeling with Adaptive Simulated Annealing  

E-print Network

approach uses Takagi-Sugeno models and Adaptive Simulated Annealing (ASA) to .... At first , and to investigate the efficiency of the ASA method in this kind of .... Kohonen SOM ( Self Organizing Map ) to realize the clustering ( or vector.

304

MATHEMATICAL MODELING OF SIMULATED PHOTOCHEMICAL SMOG  

EPA Science Inventory

This report deals with the continuing effort to develop a chemical kinetic mechanism to describe the formation of photochemical smog. Using the technique of computer modeling to simulate smog chamber data, several explicit kinetic mechanisms for specific hydrocarbons were analyze...

305

Bayesian Data—Model Integration in Plant Physiological and Ecosystem Ecology  

Microsoft Academic Search

\\u000a This paper reviews and illustrates the use of modern methods for integrating diverse data sources with process-based models\\u000a for learning about plant physiological and ecosystem processes. The particular focus is on how such data sources and models\\u000a can be coupled within a hierarchical Bayesian modeling framework. This framework, however, has been underutilized in physiological\\u000a and ecosystem ecology, despite its great

Kiona Ogle; Jarrett J. Barber

306

Post-fire ecological succession: A theoretical modeling framework  

Microsoft Academic Search

Fire is considered as an extreme disturbance in Mediterranean grasslands or shrublands as it often brings about many sudden changes in the vegetation structure, composition, and diversity patterns. In addition, it creates opportunities for exotic plant species to establish successfully in foreign habitat, and to outperform dominating native species. Monitoring and simulating post-fire successional changes, therefore, are essential tasks to

Amit Chakraborty; Bai-Lian Li

2009-01-01

307

Gecko: A Continuous 2D World for Ecological Modeling  

Microsoft Academic Search

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...

Ginger Booth

1997-01-01

308

Nutrient and plankton dynamics in an intermittently closed\\/open lagoon, Smiths Lake, south-eastern Australia: An ecological model  

Microsoft Academic Search

A spatially resolved, eleven-box ecological model is presented for an Intermittently Closed and Open Lake or Lagoon (ICOLL), configured for Smiths Lake, NSW Australia. ICOLLs are characterised by low flow from the catchment and a dynamic sand bar blocking oceanic exchange, which creates two distinct phases – open and closed. The process descriptions in the ecological model are based on

Jason D. Everett; Mark E. Baird; Iain M. Suthers

2007-01-01

309

Synergism between research and simulation models of estuarine microbial food webs.  

PubMed

Construction of mathematical simulation models helps to organize current information and extend inferences from available data. During the past two decades, microbial ecology has undergone rapid developments in both quantity and quality of available data. In particular, considerable advances have been made in our knowledge of microbial food web dynamics in the Duplin River watershed at Sapelo Island, Georgia. Here we provide examples of how modeling and microbial ecology have interfaced. In the early 1970s, construction of a 14-compartment model of carbon flow through a salt marsh ecosystem aided in directing method development and field experiments on the sediment microbial community. In turn, the results of field experiments corroborated the model's postulated controls on the community. Also, during the past 12 years we have developed a series of simulation models reflecting the growing information on the aquatic microbial food web. Early models provided evidence for the microbial loop but illustrated the paucity of knowledge concerning controls for bacterial growth on detritus. Results from newer methods in microbial ecology and studies from the Duplin River have allowed us to construct a model which provides realistic simulations but is also highly sensitive to certain parameter value changes (e.g., in organic matter availability and grazing by protozoans). Thus improvements in model structure and corroboration of the models with extant data have been closely tied to methodological and conceptual advances in microbial ecology. The relationship is viewed as synergistic, as needs for model parameter values and equation forms have directed further development of methods, experimentation, and field observations. PMID:24194331

Christian, R R; Wetzel, R L

1991-12-01

310

Verification validation and accreditation of simulation models  

Microsoft Academic Search

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

Osman Balci

1997-01-01

311

Verification, Validation And Accreditation Of Simulation Models  

Microsoft Academic Search

This paper presents guidelines for conducting verification, validation and accreditation (VV&A) of simulation models. Fifteen guiding principles are introduced to help the researchers, practitioners and managers better comprehend 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 in selecting

Osman Balci

1997-01-01

312

Simulation models for terminal homing of KEW  

Microsoft Academic Search

Generic models for a realistic simulation of a kinetic energy weapon in the terminal homing mode are studied. While these models are functional in nature and do not describe the hardware characteristics, they do describe the input-output characteristics of the state-of-the-art tactical hardware which they represent. For terminal homing simulation, a KEW was designed in sufficient detail to compute masses

Gano B. Chatterji; Robert D. Curley; Richard A. Bortins

1988-01-01

313

Simulation models for terminal homing of KEW  

NASA Astrophysics Data System (ADS)

Generic models for a realistic simulation of a kinetic energy weapon in the terminal homing mode are studied. While these models are functional in nature and do not describe the hardware characteristics, they do describe the input-output characteristics of the state-of-the-art tactical hardware which they represent. For terminal homing simulation, a KEW was designed in sufficient detail to compute masses and geometric properties such as lengths and center of gravity offsets.

Chatterji, Gano B.; Curley, Robert D.; Bortins, Richard A.

314

Minimum-complexity helicopter simulation math model  

NASA Technical Reports Server (NTRS)

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.

Heffley, Robert K.; Mnich, Marc A.

1988-01-01

315

A CONCEPTUAL MODEL FOR EVALUATING RELATIVE POTENCY DATA FOR USE IN ECOLOGICAL RISK ASSESSMENTS  

EPA Science Inventory

For chemicals with a common mechanism of toxicity, relative potency factors (RPFs) allow dose and exposure measures to be normalized to an equivalent toxicity amount of a model chemical... In ecological risk assessments the large number of possible target species, variety of expo...

316

Ecological Modelling 152 (2002) 205211 The effectiveness of various rabies spatial vaccination  

E-print Network

Ecological Modelling 152 (2002) 205­211 The effectiveness of various rabies spatial vaccination, periodic episodes of rabies epidemics erupt every 5­7 years despite low densities of the main reservoir species of rabies in this area. Canids in this desert are spread non-uniformly over space, with high

Bohrer, Gil

317

Remote sensing, ecological water quality modelling and in situ measurements: a case study in shallow lakes  

Microsoft Academic Search

The application of high spectral and spatial resolution airborne remote sensing has developed to an almost operational level. This paper investigates the role of remote sensing especially coupled to the two other available water quality assessment tools: in situ measurements and ecological water quality modelling data. A case study is presented for three shallow lakes varying in trophic level. Based

A. G. DEKKER; Ž. ZAMUROVI?-NENAD; H. J. HOOGENBOOM; S. W. M. PETERS

1996-01-01

318

COMMUNITY AND ECOSYSTEM ECOLOGY Modeling Temporal Trends in Aphid Vector Dispersal and Cucumber  

E-print Network

COMMUNITY AND ECOSYSTEM ECOLOGY Modeling Temporal Trends in Aphid Vector Dispersal and Cucumber, and epidemics have occurred more frequently since the soybean aphid, Aphis glycines Matsumura, was introduced. Major aphid vectors of CMV epidemics were identiÃ?ed by statistically relating their temporal dispersal

Nault, Brian

319

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...

320

Ecological Modelling 149 (2002) 297311 Risk assessment of the harvested pike-perch population of  

E-print Network

Ecological Modelling 149 (2002) 297­311 Risk assessment of the harvested pike-perch population is developed to assess simulta- neously the annual yield and the extinction risk of the exploited population resulting from different harvesting strategies (i.e. combinations of harvesting efforts on yearlings

Jost, Christian

321

Genetic and ecological effects of salmon farming on wild salmon: modelling from experimental results  

Microsoft Academic Search

Hindar, K., Fleming, I. A., McGinnity, P., and Diserud, O. 2006. Genetic and ecological effects of salmon farming on wild salmon: modelling from experimental results. ? ICES Journal of Marine Science, 63: 1234e1247. Cultured salmonids are released or escape into the wild in large numbers and may make up significant proportions of wild salmonid populations in fresh- and saltwater, causing

Kjetil Hindar; Ian A. Fleming; Philip McGinnity; Ola Diserud

2006-01-01

322

Using Ecological Null Models to Assess the Potential for Marine Protected Area Networks to Protect Biodiversity  

Microsoft Academic Search

Marine protected area (MPA) networks have been proposed as a principal method for conserving biological diversity, yet patterns of diversity may ultimately complicate or compromise the development of such networks. We show how a series of ecological null models can be applied to assemblage data across sites in order to identify non-random biological patterns likely to influence the effectiveness of

Brice X. Semmens; Peter J. Auster; Michelle J. Paddack; Stuart A. Sandin

2010-01-01

323

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

Microsoft Academic Search

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

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

2001-01-01

324

Ecological Modelling 221 (2010) 26992713 Contents lists available at ScienceDirect  

E-print Network

of tourist­stingray interactions at `Stingray City Sandbar' (SCS), Cayman Islands. The model predicts the state of the tourism attraction over time in relation to stingray population size, stingray life anticipated effects on stingray ecology (migration and mortality), and vice versa, thus linking the two

325

Social Ecological Model of Illness Management in High-Risk Youths with Type 1 Diabetes  

ERIC Educational Resources Information Center

In this study, the authors tested a social ecological model of illness management in high-risk, urban adolescents with Type 1 diabetes. It was hypothesized that management behaviors would be associated with individual adolescent characteristics as well as family, peer, and provider relationships. Questionnaires were collected from 96 adolescents…

Naar-King, Sylvie; Podolski, Cheryl-Lynn; Ellis, Deborah A.; Frey, Maureen A.; Templin, Thomas

2006-01-01

326

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

E-print Network

and pathogens in relation to climate change, especially global warming, has been of major concern in many predicted climate change--especially global warming--and parasitism may impact on marine host populationsGLOBAL CHANGE ECOLOGY - ORIGINAL RESEARCH Local effects of a global problem: modelling the risk

Poulin, Robert

327

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

PubMed

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

Valenzuela, Nicole

2009-07-01

328

Ten Years of the Relative Risk Model and Regional Scale Ecological Risk Assessment  

Microsoft Academic Search

It has been 10 years since the publication of the relative risk model (RRM) for regional scale ecological risk assessment. The approach has since been used successfully for a variety of freshwater, marine, and terrestrial environments in North America, South America, and Australia. During this period the types of stressors have been expanded to include more than contaminants. Invasive species,

Wayne G. Landis; Janice K. Wiegers

2007-01-01

329

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

Microsoft Academic Search

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

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

2007-01-01

330

Ecological Modelling 162 (2003) 177198 Delay dynamics of the slug Deroceras reticulatum,  

E-print Network

Ecological Modelling 162 (2003) 177­198 Delay dynamics of the slug Deroceras reticulatum species, Deroceras reticulatum, does not follow a regular annual life cycle, as do the majority of the damage is caused by Deroceras reticulatum, estimated at approx- Corresponding author. Present address

Bees, Martin

331

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

ERIC Educational Resources Information Center

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,…

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

2011-01-01

332

A simulation model of an insect population  

NSDL National Science Digital Library

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.

0002-11-30

333

Modeling and simulation of mobile satellite propagation  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

334

LAKE WATER TEMPERATURE SIMULATION MODEL  

EPA Science Inventory

Functional relationships to describe surface wind mixing, vertical turbulent diffusion, convective heat transfer, and radiation penetration based on data from lakes in Minnesota have been developed. hese relationships have been introduced by regressing model parameters found eith...

335

Modeling and simulation of luminescence detection platforms.  

PubMed

Motivated by the design of an integrated CMOS-based detection platform, a simulation model for CCD and CMOS imager-based luminescence detection systems is developed. The model comprises four parts. The first portion models the process of photon flux generation from luminescence probes using ATP-based and luciferase label-based assay kinetics. An optics simulator is then used to compute the incident photon flux on the imaging plane for a given photon flux and system geometry. Subsequently, the output image is computed using a detailed imaging sensor model that accounts for photodetector spectral response, dark current, conversion gain, and various noise sources. Finally, signal processing algorithms are applied to the image to enhance detection reliability and hence increase the overall system throughput. To validate the model, simulation results are compared to experimental results obtained from a CCD-based system that was built to emulate the integrated CMOS-based platform. PMID:15093208

Salama, Khaled; Eltoukhy, Helmy; Hassibi, Arjang; El-Gamal, Abbas

2004-06-15

336

Conceptualizing Ecology: A Learning Cycle Approach.  

ERIC Educational Resources Information Center

Proposes a teaching strategy to teach ecological concepts and terminology through the use of games and simulations. Includes examples from physiological ecology, population ecology, and ecosystem ecology. (Author/SOE)

Lauer, Thomas E.

2003-01-01

337

Campus Sustainability Planetary Health Ecological Design Social and Environmental Enterprise Incuba-tion EcoVillages Sustainable Food Systems Ecoliteracy Solutions Journal Campus Systems Model Energy  

E-print Network

a Contract for Change Ecological Economics Ecological Design Complex Systems Sustainable Business Social Systems School of Ecological Arts & Design Developing a Contract for Change Ecological Economics to transform our university into a powerful catalyst, model, and engine of positive and lasting change

Hayden, Nancy J.

338

Agent-based Modeling and Simulation  

Microsoft Academic Search

Agent-based modeling and simulation (ABMS) is a new approach to modeling systems comprised of autonomous, interacting agents. Computational advances have made possible a growing number of agent-based models across a variety of application domains. Applications range from modeling agent behavior in the stock market, supply chains, and consumer markets, to predicting the spread of epidemics, mitigating the threat of bio-warfare,

Charles M. Macal; Michael J. North

2009-01-01

339

Architecting a Simulation Framework for Model Rehosting  

NASA Technical Reports Server (NTRS)

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.

Madden, Michael M.

2004-01-01

340

Ecological Modelling 167 (2003) 97114 Modeling white sturgeon movement in a reservoir  

E-print Network

variation in dissolved oxygen and temperature. Temperature and dissolved oxygen were simulated by a CE sturgeon habitat quality was modeled as a function of temperature, dissolved oxygen and, in some cases when sturgeon were unable to leave areas with lethal temperature or dissolved oxygen conditions. Water

Jager, Henriette I.

341

Uses and requirements of ecological niche models and related distributional models  

E-print Network

of species’ distributions, asking what is different. What is more, Grinnell fully appreciated the independent nature of ecological needs, versus barriers that can interrupt or truncate distributions (Grinnell 1914). The concept of an ecological niche has... paper revisited this idea in a broader suite of species (Peterson et al. 1999), testing coincidence of ecological niche dimensions in 37 sister species pairs separated across the Isthmus of Tehuantepec, in southern Mexico—once again, each species...

Peterson, A. Townsend

2006-01-01

342

Modelling and simulation of a distributed battery management system  

Microsoft Academic Search

This paper discusses the modelling and simulation of a distributed battery management system with a continuous and discrete-event simulation environment. The simulation model focuses on replicating the generic components within the system into model blocks to provide a structured approach in simulating battery networks. The simulation model also deals with three key network levels, which are the process level, the

Darren LIM; A. Anbuky

2004-01-01

343

University of Michigan scientists modeling cancer using ecological principles:  

Cancer.gov

The invasion of a new species into an established ecosystem can be directly compared to the steps involved in cancer metastasis. New [University of Michigan] research published in BioMed Central's open access journal Theoretical Biology and Medical Modelling uses the Tilman model of competition between invasive species to study the metastasis of prostate cells into bone.

344

The Ecology of Human Development: Evolving Models for Cultural Psychology  

Microsoft Academic Search

The Whiting model aimed to provide a blueprint for psychocultural research by generating testable hypotheses about the dynamic relationships of a culture with the psychology and behavior of its members. This analysis identifies reasons why the model was so effective at generating hypotheses borne out in empirical research, including its foundational insight that integrated nature and nurture, its reconceptualization of

Carol M. Worthman

2010-01-01

345

ORIGINAL ARTICLE Climate downscaling effects on predictive ecological models  

E-print Network

the scale of climate change and sea-level rise threats to human and natural systems (IPCC 2007), forecasting envelope model Á Downscaling Á Species distribution model Á Florida Á Endangered species Introduction Given Research and Education Center, University of Florida, 3205 College Avenue, Fort Lauderdale, FL 33314, USA e

Mazzotti, Frank

346

Linking dynamic economic and ecological general equilibrium models  

Microsoft Academic Search

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

David Finnoff; John Tschirhart

2008-01-01

347

On identification in Bayesian disease mapping and ecological-spatial regression models.  

PubMed

We discuss identification of structural characteristics of the underlying relative risks ensemble for posterior relative risks inference within Bayesian generalized linear mixed model framework for small-area disease mapping and ecological-spatial regression. We revisit conditionally specified and locally characterized Gaussian Markov random field risks ensemble priors in univariate disease mapping and communicate insight into Gaussian Markov random field variance-covariance characteristics for representing disease risks variability and spatial risks interactions and for structural identification with respect to risks ensemble prior choices. Illustrative examples of identification in Bayesian disease mapping and ecological-spatial regression models are presented for Bayesian hierarchical generalized linear mixed Poisson models and zero-inflated Poisson models. PMID:22573502

MacNab, Ying C

2014-04-01

348

ECO-LIFE: A Simulation of an Ecological System. Student Booklet.  

ERIC Educational Resources Information Center

This document contains an instructional unit which deals with one major topic in ecology. It focuses on the variables which affect the development of populations and determine their final size within a given period of time. The variables operating in nature which determine the development of populations are numerous, thus complicating the task of…

Chen, David

349

Revolutions in energy through modeling and simulation  

SciTech Connect

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.

Tatro, M.; Woodard, J.

1998-08-01

350

Atmospheric model intercomparison project: Monsoon simulations  

SciTech Connect

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.

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

351

SIMULATION MODELS OF TRAFFIC FLOW  

Microsoft Academic Search

This paper reviews the range of traffic models, with particular attention to microsimulation. Although there are major types, there are so many hybrids that it is difficult to classify them all. The standard way of assigning traffic to a network is to find a static equilibrium from which no driver would be able to find a quicker route. This gives

John Taplin

352

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

Microsoft Academic Search

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

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

2006-01-01

353

Model averaging, missing data and multiple imputation: a case study for behavioural ecology  

Microsoft Academic Search

Model averaging, specifically information theoretic approaches based on Akaike’s information criterion (IT-AIC approaches),\\u000a has had a major influence on statistical practices in the field of ecology and evolution. However, a neglected issue is that\\u000a in common with most other model fitting approaches, IT-AIC methods are sensitive to the presence of missing observations.\\u000a The commonest way of handling missing data is

Shinichi Nakagawa; Robert P. Freckleton

2011-01-01

354

Efficient ecosystem services and naturalness in an ecological\\/economic model  

Microsoft Academic Search

In an integrated economic\\/ecological model, the economy benefits from ecosystem services that include: (1) the consumptive\\u000a use of a harvested species, (2) the non-consumptive use of popular species, and (3) naturalness, i.e., the divergence of the\\u000a ecosystem’s biodiversity from its natural steady state. The biological component of the model, which is applied to a nine-species\\u000a Alaskan marine ecosystem, relies on

Thomas Eichner; John Tschirhart

2007-01-01

355

PROGRESS IN PHOTOCHEMICAL AIR QUALITY SIMULATION MODELING  

EPA Science Inventory

Within the class of existing or conceived photochemical air quality simulation models (PAQSM's) there are only several basic approaches. The United States Environmental Protection Agency (U.S. EPA) in the mid-1970's reviewed the various urban scale models which were in existence ...

356

Transient fault modeling and fault injection simulation  

E-print Network

An accurate transient fault model is presented in this thesis. A 7-term exponential current upset model is derived from the results of a device-level, 3-dimensional, single-event-upset simulation. A curve-fitting algorithm is used to extract...

Yuan, Xuejun

2012-06-07

357

Non-linear transformer modeling and simulation  

SciTech Connect

Transformers models for simulation with Pspice and Analogy`s Saber are being developed using experimental B-H Loop and network analyzer measurements. The models are evaluated for accuracy and convergence using several test circuits. Results are presented which demonstrate the effects on circuit performance from magnetic core losses eddy currents and mechanical stress on the magnetic cores.

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

1994-08-01

358

Rotor systems research aircraft simulation mathematical model  

NASA Technical Reports Server (NTRS)

An analytical model developed for evaluating and verifying advanced rotor concepts is discussed. The model was used during in both open loop and real time man-in-the-loop simulation during the rotor systems research aircraft design. Future applications include: pilot training, preflight of test programs, and the evaluation of promising concepts before their implementation on the flight vehicle.

Houck, J. A.; Moore, F. L.; Howlett, J. J.; Pollock, K. S.; Browne, M. M.

1977-01-01

359

Univariate input models for stochastic simulation  

Microsoft Academic Search

Techniques are presented for modeling and randomly sampling many of the multivariate probabilistic input processes that drive discrete-event simulation experiments. Emphasis is given to bivariate and trivariate extensions of the univariate beta, Johnson, and Bézier dist ribution families because of the flexibility of these families to model a wide range of shapes for the marginal distributions while also representing the

Michael E. Kuhl; Julie S. Ivy; Emily K. Lada; Natalie M. Steiger; Mary Ann Flanigan Wagner; James R. Wilson

2010-01-01

360

Structural and behavioral equivalence of simulation models  

Microsoft Academic Search

It M sometimes desu-able to know when two different discrete-event simulation models are, in some sense, interchangeable; that is, whether or not the two models always have the same output when run under identical experimental conditions. This notion of behavioral equivalence, while conceptually simple, is difficult to define in a manner that is both useful and testable. It is difficult

Enver Yücesan; Lee Schruben

1992-01-01

361

Verifying and validating a simulation model  

Microsoft Academic Search

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.

Anbin Hu; Ye San; Zicai Wang

2001-01-01

362

Verifying and validating a simulation model  

Microsoft Academic Search

This paper presents the verification and validation of a simulation model with the emphasis on 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 related terms are used in verifying and validating an existing model

Anbin Hu; Ye San; Zicai Wang

2001-01-01

363

MGAS. METC-Gasifier Advanced Simulation Model  

SciTech Connect

MGAS is a mechanistic model for describing the transient operation of coflow, counterflow, or fixed-bed gasifiers. The model describes the gasifier in one or two dimensions and can simulate the addition, withdrawal, or recycle of gas and solids at multiple locations in the bed.

Syamlal, M. [EG and G, W.A.S.C. Inc., Morgantown, WV (United States); Bissett, L.A. [USDOE Morgantown Energy Tech. Ctr., WV (United States)

1991-01-01

364

Interactively deformable models for surgery simulation  

Microsoft Academic Search

A methodology that addresses important issues concerned with the underlying graphical models designed for surgical simulation, as well as issues related to the real-time interactivity with, and manipulation of, these models is presented. The specific application of interest is laparoscopic surgery, which is performed using endoscopes that present a video image of the organs to the clinicians. The surgeon then

N. F. Ezquerra; J. F. O'Brien; R. Rowe; T. Gadacz; E. Palm

1993-01-01

365

Modeling and simulation of dielectric elastomer actuators  

Microsoft Academic Search

Dielectric elastomers are used as base material for so-called electroactive polymer (EAP) actuators. A procedure and a specific constitutive model (for the acrylic elastomer VHB 4910) are presented in this work for finite element modeling and simulation of dielectric elastomer actuators of general shape and set-up. The Yeoh strain energy potential and the Prony series are used for describing the

Michael Wissler; Edoardo Mazza

2005-01-01

366

Estimating Environmental Drivers for Broad-Scale Ecological Models: Comparing Performance of Modeled Stream Flow and Meteorological Observations  

NASA Astrophysics Data System (ADS)

Fisheries ecologists are charged with assessing the impact of climate and land use changes on wild fish populations. Their ecological population models require estimates of environmental drivers, stream flow and stream temperature, across broad spatial scales. Observation data is frequently not available at that scale, especially for smaller streams and headwaters that are the habitat for target species. As estimates at a coarse temporal resolution are sufficient for many ecological population models, it is possible to develop regionalized models across the broad spatial scale required with the limited observations available. It may also be possible to use measures of air temperature and precipitation, for which meteorological observations are more readily available, as proxy metrics for stream flow and stream temperature. Since additional sources of model uncertainty are avoided by using the proxy measures, it is important to evaluate whether modeled stream flow provides enough improvement to the ecological models to justify this introduction of uncertainty. We employ wild brook trout occupancy models to evaluate these different environmental inputs. We present a regionalized model for estimating stream flow at the seasonal time-step, and a model of summary statistics. Performance of fish occupancy models using each of these estimates is then compared to the performance of a fish occupancy model using meteorological measures as the environmental driver.

Rosner, A.; Letcher, B. H.; Kanno, Y.

2013-12-01

367

Probabilistic ecological risk assessment of DDTs in the Bohai Bay based on a food web bioaccumulation model.  

PubMed

The fugacity-based food web model was developed to simulate the bioaccumulation of dichloro-diphenyl-trichloroethanes (DDTs) in the aquatic ecosystem in the Bohai Bay. The internal exposure levels (IELs) of DDTs in various organism categories were calculated. Monte Carlo-based uncertainty analysis was performed to get the of IEL distributions of DDTs in organisms. Probabilistic ecological risk assessment (ERA) was performed based on IEL distributions and internal species sensitivity distributions (SSDs). The results show that fugacities and bioaccumulation factors (BAFs) generally increased with increasing trophic level in the food web. Octanol-water partition coefficient (K(ow)), DDT levels in water and the lipid contents had the greatest influences on IELs in the organism bodies. The ecological risks of DDTs were relatively high. The risk order was p,p'-DDT>p,p'-DDE>p,p'-DDD. At an internal hazard quotient (HQ(int)) criterion of 1/5, the risk probabilities were 0.10 (0.055-0.17), 0.079 (0.045-0.13) and 0.053 (0.028-0.092) for p,p'-DDT, p,p'-DDE and p,p'-DDD, respectively. The results from ERA based on the internal exposure approximated those based on external exposure. The food web model is a feasible method to predict the extent of bioaccumulation and IELs of hydrophobic organic pollutants in organisms as a step to evaluate their risk posed on aquatic ecosystems. PMID:21075423

Wang, Bin; Yu, Gang; Huang, Jun; Wang, Tai; Hu, Hongying

2011-01-01

368

Modeling Physics with Easy Java Simulations  

NASA Astrophysics Data System (ADS)

Modeling has been shown to correct weaknesses of traditional instruction by engaging students in the design of physical models to describe, explain, and predict phenomena. Although the modeling method can be used without computers, the use of computers allows students to study problems that are difficult and time consuming, to visualize their results, and to communicate their results with others. This combination of computer modeling with theory and experiment can achieve insight and understanding that cannot be achieved with only one approach. This paper describes the Easy Java Simulations (Ejs) modeling and authoring tool and shows how it can be used to teach mechanics concepts with computer modeling.

Christian, Wolfgang; Esquembre, Francisco

2007-11-01

369

Requirements for psychological models to support design: Towards ecological task analysis  

NASA Technical Reports Server (NTRS)

Cognitive engineering is largely concerned with creating environmental designs to support skillful and effective human activity. A set of necessary conditions are proposed for psychological models capable of supporting this enterprise. An analysis of the psychological nature of the design product is used to identify a set of constraints that models must meet if they can usefully guide design. It is concluded that cognitive engineering requires models with resources for describing the integrated human-environment system, and that these models must be capable of describing the activities underlying fluent and effective interaction. These features are required in order to be able to predict the cognitive activity that will be required given various design concepts, and to design systems that promote the acquisition of fluent, skilled behavior. These necessary conditions suggest that an ecological approach can provide valuable resources for psychological modeling to support design. Relying heavily on concepts from Brunswik's and Gibson's ecological theories, ecological task analysis is proposed as a framework in which to predict the types of cognitive activity required to achieve productive behavior, and to suggest how interfaces can be manipulated to alleviate certain types of cognitive demands. The framework is described in terms, and illustrated with an example from the previous research on modeling skilled human-environment interaction.

Kirlik, Alex

1991-01-01

370

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...

371

Mars Smart Lander Parachute Simulation Model  

NASA Technical Reports Server (NTRS)

A multi-body flight simulation for the Mars Smart Lander has been developed that includes six degree-of-freedom rigid-body models for both the supersonically-deployed and subsonically-deployed parachutes. This simulation is designed to be incorporated into a larger simulation of the entire entry, descent and landing (EDL) sequence. The complete end-to-end simulation will provide attitude history predictions of all bodies throughout the flight as well as loads on each of the connecting lines. Other issues such as recontact with jettisoned elements (heat shield, back shield, parachute mortar covers, etc.), design of parachute and attachment points, and desirable line properties can also be addressed readily using this simulation.

Queen, Eric M.; Raiszadeh, Ben

2002-01-01

372

PIXE simulation: Models, methods and technologies  

SciTech Connect

The simulation of PIXE (Particle Induced X-ray Emission) is discussed in the context of general-purpose Monte Carlo systems for particle transport. Dedicated PIXE codes are mainly concerned with the application of the technique to elemental analysis, but they lack the capability of dealing with complex experimental configurations. General-purpose Monte Carlo codes provide powerful tools to model the experimental environment in great detail, but so far they have provided limited functionality for PIXE simulation. This paper reviews recent developments that have endowed the Geant4 simulation toolkit with advanced capabilities for PIXE simulation, and related efforts for quantitative validation of cross sections and other physical parameters relevant to PIXE simulation.

Batic, M. [INFN Sezione di Genova, Via Dodecaneso 33, 16146 Genova, Italy and Jozef Stefan Institute, Jamova cesta 39, Ljubljana 1000 (Slovenia); Pia, M. G.; Saracco, P. [INFN Sezione di Genova, Via Dodecaneso 33, 16146 Genova (Italy); Weidenspointner, G. [Max-Planck-Institut Halbleiterlabor, Otto-Hahn-Ring 6, 81739 Muenchen (Germany) and Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse, Garching 85748 (Germany)

2013-04-19

373

Development of NASA's Models and Simulations Standard  

NASA Technical Reports Server (NTRS)

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.

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

2008-01-01

374

Ecological hierarchies and self-organisation - Pattern analysis, modelling and process integration across scales  

USGS Publications Warehouse

A continuing discussion in applied and theoretical ecology focuses on the relationship of different organisational levels and on how ecological systems interact across scales. We address principal approaches to cope with complex across-level issues in ecology by applying elements of hierarchy theory and the theory of complex adaptive systems. A top-down approach, often characterised by the use of statistical techniques, can be applied to analyse large-scale dynamics and identify constraints exerted on lower levels. Current developments are illustrated with examples from the analysis of within-community spatial patterns and large-scale vegetation patterns. A bottom-up approach allows one to elucidate how interactions of individuals shape dynamics at higher levels in a self-organisation process; e.g., population development and community composition. This may be facilitated by various modelling tools, which provide the distinction between focal levels and resulting properties. For instance, resilience in grassland communities has been analysed with a cellular automaton approach, and the driving forces in rodent population oscillations have been identified with an agent-based model. Both modelling tools illustrate the principles of analysing higher level processes by representing the interactions of basic components.The focus of most ecological investigations on either top-down or bottom-up approaches may not be appropriate, if strong cross-scale relationships predominate. Here, we propose an 'across-scale-approach', closely interweaving the inherent potentials of both approaches. This combination of analytical and synthesising approaches will enable ecologists to establish a more coherent access to cross-level interactions in ecological systems. ?? 2010 Gesellschaft f??r ??kologie.

Reuter, H.; Jopp, F.; Blanco-Moreno, J. M.; Damgaard, C.; Matsinos, Y.; DeAngelis, D. L.

2010-01-01

375

Fast simulation of facilitated spin models  

NASA Astrophysics Data System (ADS)

We show how to apply the absorbing Markov chain Monte Carlo algorithm of Novotny to simulate kinetically constrained models of glasses. We consider in detail one-spin facilitated models, such as the East model and its generalizations to arbitrary dimensions. We investigate how to maximize the efficiency of the algorithms, and show that simulation times can be improved on standard continuous time Monte Carlo by several orders of magnitude. We illustrate the method with equilibrium and aging results. These include a study of relaxation times in the East model for dimensions d = 1 to 13, which provides further evidence that the hierarchical relaxation in this model is present in all dimensions. We discuss how the method can be applied to other kinetically constrained models.

Ashton, Douglas J.; Hedges, Lester O.; Garrahan, Juan P.

2005-12-01

376

Use of an integrated flow model to estimate ecologically relevant hydrologic characteristics at stream biomonitoring sites  

USGS Publications Warehouse

We developed an integrated hydroecological model to provide a comprehensive set of hydrologic variables representing five major components of the flow regime at 856 aquatic-invertebrate monitoring sites in New Jersey. The hydroecological model simulates streamflow by routing water that moves overland and through the subsurface from atmospheric delivery to the watershed outlet. Snow accumulation and melt, evapotranspiration, precipitation, withdrawals, discharges, pervious- and impervious-area runoff, and lake storage were accounted for in the water balance. We generated more than 78 flow variables, which describe the frequency, magnitude, duration, rate of change, and timing of flow events. Highly correlated variables were filtered by principal component analysis to obtain a non-redundant subset of variables that explain the majority of the variation in the complete set. This subset of variables was used to evaluate the effect of changes in the flow regime on aquatic-invertebrate assemblage structure at 856 biomonitoring sites. We used non-metric multidimensional scaling (NMS) to evaluate variation in aquatic-invertebrate assemblage structure across a disturbance gradient. We employed multiple linear regression (MLR) analysis to build a series of MLR models that identify the most important environmental and hydrologic variables driving the differences in the aquatic-invertebrate assemblages across the disturbance gradient. The first axis of NMS ordination was significantly related to many hydrologic, habitat, and land-use/land-cover variables, including the average number of annual storms producing runoff, ratio of 25-75% exceedance flow (flashiness), diversity of natural stream substrate, and the percentage of forested land near the stream channel (forest buffer). Modifications in the hydrologic regime as the result of changes in watershed land use appear to promote the retention of highly tolerant aquatic species; in contrast, species that are sensitive to hydrologic instability and other anthropogenic disturbance become much less prevalent. We also found strong relations between an index of invertebrate-assemblage impairment, its component metrics, and the primary disturbance gradient. The process-oriented watershed modeling approach used in this study provides a means to evaluate how natural landscape features interact with anthropogenic factors and assess their effects on flow characteristics and stream ecology. By combining watershed modeling and indirect ordination techniques, we were able to identify components of the hydrologic regime that have a considerable effect on aquatic-assemblage structure and help in developing short- and long-term management measures that mitigate the effects of anthropogenic disturbance in stream systems.

Kennen, J. G.; Kauffman, L. J.; Ayers, M. A.; Wolock, D. M.; Colarullo, S. J.

2008-01-01

377

Teaching and Learning Ecological Modeling over the Web: a Collaborative Approach  

NSDL National Science Digital Library

This online report, published in Conservation Ecology, describes the framework for web-based collaborative teaching, and provides the layout of an ecological modeling course as an example of how this method of teaching can be implemented. The course content consists of reading materials that describe the theory of systems analysis and modeling, guidelines on how models can be built, and numerous examples and illustrations. The interactive portion includes exercises that can be discussed with and evaluated by the instructor, and provides a means to mimic class discussions. In addition to the course content, the report also offers a discussion of the availability and relevance of other web-based tools, including links to those discussed.

Voinov, Alexy

2010-02-16

378

Modeling and Simulation. 3. Simulation of a Model for Development of Visual Cortical Specificity.  

National Technical Information Service (NTIS)

This document presents a tutorial describing aspects of the coding of computerized simulations of models of visual cortical development. The model considered has an anatomy of an excitatory projection from thalamus to cortex combined with intracortical in...

A. B. Saul, E. E. Clothiaux

1986-01-01

379

Natural history collections and the conservation of poorly known taxa: Ecological niche modeling in central African rainforest genets ( Genetta spp.)  

Microsoft Academic Search

Natural history collections are crucial resources for conservation biology, particularly given the development of the ecological niche modeling (ENM) approach. We combined ENM with taxonomic investigations to address ecological, geographic, and phenotypic variation in the poorly known central African rainforest genets (Genetta cristata, Genetta servalina, Genetta victoriae) to provide new insights into their conservation status. Taxonomic identification was based on

P. Gaubert; M. Pape?; A. T. Peterson

2006-01-01

380

Incorporation of RAM techniques into simulation modeling  

NASA Astrophysics Data System (ADS)

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.

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

1995-01-01

381

An Online Database for Informing Ecological Network Models: http://kelpforest.ucsc.edu  

PubMed Central

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

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

382

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

USGS Publications Warehouse

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/data?baseui).

Beas-Luna, Rodrigo; Tinker, M. Tim; Novak, Mark; Carr, Mark H.; Black, August; Caselle, Jennifer E.; Hoban, Michael; Malone, Dan; Iles, Alison C.

2014-01-01

383

Author's personal copy Ecological Modelling 221 (2010) 23742387  

E-print Network

-based model Human­wildlife interaction Wolf Banff National Park Kootenay National Park Human impact Recreation to investi- gate how varying levels of human presence could affect elements of wolf behavior, including were noticeably affected by the intensity of human pres- ence. The packs' home ranges shrank and wolves

Hebblewhite, Mark

384

Using structural equation modeling to investigate relationships among ecological variables  

Microsoft Academic Search

Structural equation modeling is an advanced multivariate statistical process with which a researcher can construct theoretical concepts, test their measurement reliability, hypothesize and test a theory about their relationships, take into account measurement errors, and consider both direct and indirect effects of variables on one another. Latent variables are theoretical concepts that unite phenomena under a single term, e.g., ecosystem

Ziad A. Malaeb; J. Kevin Summers; Bruce H. Pugesek

2000-01-01

385

Cognitive Niches: An Ecological Model of Strategy Selection  

ERIC Educational Resources Information Center

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…

Marewski, Julian N.; Schooler, Lael J.

2011-01-01

386

Author's personal copy Ecological Modelling 221 (2010) 27602768  

E-print Network

Scientific communication Standardization a b s t r a c t The `ODD' (Overview, Design concepts, and Details in ODD but also two emerg- ing, and unanticipated, benefits: ODD improves the rigorous formulation and social scientists have long been faced with the challenge of how to model the complexity inherent in many

Tesfatsion, Leigh

387

Understanding the Codevelopment of Modeling Practice and Ecological Knowledge  

ERIC Educational Resources Information Center

Despite a recent focus on engaging students in epistemic practices, there is relatively little research on how learning environments can support the simultaneous, coordinated development of both practice and the knowledge that emerges from and supports scientific activity. This study reports on the co-construction of modeling practice and…

Manz, Eve

2012-01-01

388

Big questions, small worlds: microbial model systems in ecology  

E-print Network

of spatial and temporal scales. Microorganisms are also amenable to genetic manipulation and to prolonged of genetic and physiological information available for commonly used microorganisms, combined biologists have embraced microbial model systems as tools to address genetic and physio- logical questions

Buckling, Angus

389

Prediction of the environmental fate and aquatic ecological impact of nitrobenzene in the Songhua River using the modified AQUATOX model.  

PubMed

An accidental discharge of nitrobenzene happened in November 2005 in the Songhua River, China. The AQUATOX model was modified and adapted to simulate the time-dependent nitrobenzene distribution in this multimedia aquatic system and its potential ecological impacts. Nitrobenzene concentrations in flowing water, sediment, and biota were predicted. Based on the initial concentrations of nitrobenzene observed in the field during the accidental discharge, that is, 0.167-1.47 mg/L at different river segments, the predicted water concentrations of nitrobenzene would be lower than 0.02 and 0.002 mg/L after twenty days and one month, respectively. Both model prediction and field observation were in good agreement. The predicted nitrobenzene concentrations in sediments and aquatic organisms would be lower than 0.025 and 0.002 mg/kg, respectively, after two months. Among the environmental factors affecting nitrobenzene concentrations in water, inflow water dilution, water temperature, and initial concentration were the most important, by sensitivity analysis. Comparing the perturbed simulation and control simulation, the biomass changes for diatoms and mussel were significantly affected, whereas, no influence on other organisms could be predicted. Therefore the results indicated that nitrobenzene pollution in the Songhua River should have a limited impact on the benthos community. PMID:18814570

Lei, Bingli; Huang, Shengbiao; Qiao, Min; Li, Tianyun; Wang, Zijian

2008-01-01

390

A Petri Net Approach to Verify and Debug Simulation Models  

Microsoft Academic Search

Verification and Simulation share many issues, one is that simulation models require validation and verification. In the context of simulation, verification is understood as the task to ensure that an exe- cutable simulation model matches its conceptual counterpart while vali- dation is the task to ensure that a simulation model represents the sys- tem under study well enough with respect

Peter Kemper; Carsten Tepper

2006-01-01

391

Simulation and critical care modeling Jennifer E. Krekea  

E-print Network

Simulation and critical care modeling Jennifer E. Krekea , Andrew J. Schaefera,b,c and Mark S in the literature suggest that simulation modeling techniques such as Markov modeling, Monte Carlo simulation, and discrete-event simulation are useful tools for analyzing complex systems in critical care. These simulation

Schaefer, Andrew

392

Distributed earth model/orbiter simulation  

NASA Technical Reports Server (NTRS)

Distributed Earth Model/Orbiter Simulation (DEMOS) is a network based application developed for the UNIX environment that visually monitors or simulates the Earth and any number of orbiting vehicles. Its purpose is to provide Mission Control Center (MCC) flight controllers with a visually accurate three dimensional (3D) model of the Earth, Sun, Moon and orbiters, driven by real time or simulated data. The project incorporates a graphical user interface, 3D modelling employing state-of-the art hardware, and simulation of orbital mechanics in a networked/distributed environment. The user interface is based on the X Window System and the X Ray toolbox. The 3D modelling utilizes the Programmer's Hierarchical Interactive Graphics System (PHIGS) standard and Raster Technologies hardware for rendering/display performance. The simulation of orbiting vehicles uses two methods of vector propagation implemented with standard UNIX/C for portability. Each part is a distinct process that can run on separate nodes of a network, exploiting each node's unique hardware capabilities. The client/server communication architecture of the application can be reused for a variety of distributed applications.

Geisler, Erik; Mcclanahan, Scott; Smith, Gary

1989-01-01

393

Radiation, Ecology and the Invalid LNT Model: The Evolutionary Imperative  

PubMed Central

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

Parsons, Peter A.

2006-01-01

394

METC Gasifier Advanced Simulation (MGAS) model  

SciTech Connect

Morgantown Energy Technology Center is developing an advanced moving-bed gasifier, which is the centerpiece of the Integrated Gasifier Combined-Cycle (IGCC) system, with the features of good efficiency, low cost, and minimal environmental impact. A mathematical model of the gasifier, the METC-Gasifier Advanced Simulation (MGAS) model, has been developed for the analysis and design of advanced gasifiers and other moving-bed gasifiers. This report contains the technical and the user manuals of the MGAS model. The MGAS model can describe the transient operation of coflow, counterflow, or fixed-bed gasifiers. It is a one-dimensional model and can simulate the addition and withdrawal of gas and solids at multiple locations in the bed, a feature essential for simulating beds with recycle. The model describes the reactor in terms of a gas phase and a solids (coal or char) phase. These phases may exist at different temperatures. The model considers several combustion, gasification, and initial stage reactions. The model consists of a set of mass balances for 14 gas species and three coal (pseudo-) species and energy balances for the gas and the solids phases. The resulting partial differential equations are solved using a finite difference technique.

Syamlal, M. [EG and G Washington Analytical Services Center, Inc., Morgantown, WV (United States); Bissett, L.A. [USDOE Morgantown Energy Technology Center, WV (United States)

1992-01-01

395

Rainforest carbon cycling and biodiversity: A simulation model learning tool  

NSDL National Science Digital Library

This modeling activity simulates how atmospheric CO2 concentrations, which influence global climate, increase with deforestation and decrease during reforestation. As fast-growing tropical trees sequester carbon via the process of photosynthesis, carbon also cycles through trees, soil, animals, and back to the atmosphere via respiration and decomposition. Students gain hands-on experience in exploring carbon cycling, and linkages with nutrient cycling and food chains. The quantitative aspects of this activity promote integration of mathematical skills with scientific concepts. The model is downloadable (PCÃÂs only, ExtendSim software, ImagineThat, Inc.) for free at: www.nrem.iastate.edu/ECOS/rfsims.html. This animated, interactive, game-like, bilingual model of a tropical rainforest contains an instructional video, a tutorial-like ÃÂlesson paneÃÂ, and four Levels with different ecological concepts and levels of complexity. Concepts include the law of conservation of matter in relation to carbon cycling between land and atmosphere. Three ÃÂstateÃÂ variables ÃÂ sunlight, rain, and nutrients ÃÂ are adjustable, as is land use, which toggles between pasture and forest in Level 4. Food webs and detrital fluxes are portrayed within an ecosystems context, such that biodiversity declines as habitat becomes degraded. Storages and fluxes are animated with icons to provide a visual sense of the modelÃÂs quantitative basis; actual quantities are provided in spreadsheet and graphic form. Students can thus engage actively in the scientific method by posing questions and formulating hypotheses. They can gather data from running the model at different experimental levels of the state variables to test hypotheses, evaluate the data collected, and present results in essays, posters, or Powerpoints.This material is based on work supported by the U.S. National Science Foundation (Grants DEB 0703561 and 1119223). The simulation model was used in the 2008 Fairchild Challenge: http://www.fairchildgarden.org/education/fclinks/rainforestmodel/.

Russell, Ann E.

2012-02-24

396

A Transmission Model for the Ecology of an Avian Blood Parasite in a Temperate Ecosystem  

PubMed Central

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

Murdock, Courtney C.; Foufopoulos, Johannes; Simon, Carl P.

2013-01-01

397

A transmission model for the ecology of an avian blood parasite in a temperate ecosystem.  

PubMed

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

Murdock, Courtney C; Foufopoulos, Johannes; Simon, Carl P

2013-01-01

398

Bridging the gap between theoretical ecology and real ecosystems: modeling invertebrate community composition in streams.  

PubMed

For the first time, we combine concepts of theoretical food web modeling, the metabolic theory of ecology, and ecological stoichiometry with the use of functional trait databases to predict the coexistence of invertebrate taxa in streams. We developed a mechanistic model that describes growth, death, and respiration of different taxa dependent on various environmental influence factors to estimate survival or extinction. Parameter and input uncertainty is propagated to model results. Such a model is needed to test our current quantitative understanding of ecosystem structure and function and to predict effects of anthropogenic impacts and restoration efforts. The model was tested using macroinvertebrate monitoring data from a catchment of the Swiss Plateau. Even without fitting model parameters, the model is able to represent key patterns of the coexistence structure of invertebrates at sites varying in external conditions (litter input, shading, water quality). This confirms the suitability of the model concept. More comprehensive testing and resulting model adaptations will further increase the predictive accuracy of the model. PMID:23691656

Schuwirth, Nele; Reichert, Peter

2013-02-01

399

Technical Report 2003 -3 MODELING AND SIMULATION OF  

E-print Network

. Technical Report 2003 - 3 MODELING AND SIMULATION OF IEEE 14 BUS SYSTEM WITH FACTS CONTROLLERS Models . . . . . . . . . . . . . . . . . . . 9 2 TOOLS AND SIMULATION RESULTS 16 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 2.2 Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.3 Simulation

Cañizares, Claudio A.

400

A coupled geomorphic and ecological model of tidal marsh evolution.  

PubMed

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

Kirwan, Matthew L; Murray, A Brad

2007-04-10

401

A coupled geomorphic and ecological model of tidal marsh evolution  

PubMed Central

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

Kirwan, Matthew L.; Murray, A. Brad

2007-01-01

402

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

Microsoft Academic Search

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

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

2011-01-01

403

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...

404

Modeling and Simulation of Nuclear Fuel Materials  

SciTech Connect

We review the state of modeling and simulation of nuclear fuels with emphasis on the most widely used nuclear fuel, UO2. The hierarchical scheme presented represents a science-based approach to modeling nuclear fuels by progressively passing information in several stages from ab initio to continuum levels. Such an approach is essential to overcome the challenges posed by radioactive materials handling, experimental limitations in modeling extreme conditions and accident scenarios and small time and distance scales of fundamental defect processes. When used in conjunction with experimental validation, this multiscale modeling scheme can provide valuable guidance to development of fuel for advanced reactors to meet rising global energy demand.

Devanathan, Ram [Pacific Northwest National Laboratory (PNNL); Van Brutzel, Laurent [LSCE/CEA, Gif-sur-Yvette, France; Chartier, Alain [LSCE/CEA, Gif-sur-Yvette, France; Christine, Gueneau [LSCE/CEA, Gif-sur-Yvette, France; Mattsson, Ann [Sandia National Laboratories (SNL); Tikare, Veena [Sandia National Laboratories (SNL); Bartel, Timothy [Sandia National Laboratories (SNL); Besmann, Theodore M [ORNL; Stan, Marius [Los Alamos National Laboratory (LANL); Van Uffelen, Paul [Institute for Transuranium Elements, Germany

2010-01-01

405

Nutritional models for a Controlled Ecological Life Support System (CELSS): Linear mathematical modeling  

NASA Technical Reports Server (NTRS)

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.

Wade, Rose C.

1989-01-01

406

Modelling the ecological consequences of whole tree harvest for bioenergy production  

NASA Astrophysics Data System (ADS)

There is an increasing demand for energy from biomass as a substitute to fossil fuels worldwide, and the Norwegian government plans to double the production of bioenergy to 9% of the national energy production or to 28 TWh per year by 2020. A large part of this increase may come from forests, which have a great potential with respect to biomass supply as forest growth increasingly has exceeded harvest in the last decades. One feasible option is the utilization of forest residues (needles, twigs and branches) in addition to stems, known as Whole Tree Harvest (WTH). As opposed to WTH, the residues are traditionally left in the forest with Conventional Timber Harvesting (CH). However, the residues contain a large share of the treés nutrients, indicating that WTH may possibly alter the supply of nutrients and organic matter to the soil and the forest ecosystem. This may potentially lead to reduced tree growth. Other implications can be nutrient imbalance, loss of carbon from the soil and changes in species composition and diversity. This study aims to identify key factors and appropriate strategies for ecologically sustainable WTH in Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) forest stands in Norway. We focus on identifying key factors driving soil organic matter, nutrients, biomass, biodiversity etc. Simulations of the effect on the carbon and nitrogen budget with the two harvesting methods will also be conducted. Data from field trials and long-term manipulation experiments are used to obtain a first overview of key variables. The relationships between the variables are hitherto unknown, but it is by no means obvious that they could be assumed as linear; thus, an ordinary multiple linear regression approach is expected to be insufficient. Here we apply two advanced and highly flexible modelling frameworks which hardly have been used in the context of tree growth, nutrient balances and biomass removal so far: Generalized Additive Models (GAMs) and Random Forests. Results obtained for GAMs so far show that there are differences between WTH and CH in two directions: both the significance of drivers and the shape of the response functions differ. GAMs turn out to be a flexible and powerful alternative to multivariate linear regression. The restriction to linear relationships seems to be unjustified in the present case. We use Random Forests as a highly efficient classifier which gives reliable estimates for the importance of each driver variable in determining the diameter growth for the two different harvesting treatments. Based on the final results of these two modelling approaches, the study contributes to find appropriate strategies and suitable regions (in Norway) where WTH may be sustainable performed.

Skår, Silje; Lange, Holger; Sogn, Trine

2013-04-01

407

Ecological models of the Mississippi Deltaic Plain Region: data collection and presentation  

SciTech Connect

This report consists of quantified ecosystem models with input-output matrices of the biology, hydrology, geology, and socioeconomics of the major habitats of the Mississippi Deltaic Plain Region. The quantitative framework characterizes the region and provides a data base for future ecological models. The habitats modeled are aggregated from those previously identified in the MDPR by Wicker et al. (1980) according to the classification system of Cowardin et al. (1979). This report was designed to supplement the companion narrative description of the Mississippi Deltaic Plan Region as the final products in the Mississippi Deltaic Plain Region Characterization Study. Together these two volumes provide both general descriptions and detailed data on the region.

Costanza, R.; Neill, C.; Leibowitz, S.G.; Fruci, J.R.; Bahr, L.M. Jr.; Day, J.W. Jr.

1983-03-01

408

Ocean background model for scene simulation  

Microsoft Academic Search

An ocean surface model for synthetic IR\\/visible imaging applications has been developed at GTRI based upon the Pierson-Moskowitz wave spectrum. The model calculates a 2D grid of height values describing a given snapshot of the sea surface. This surface is a function of wind speed and direction as well as elapsed time into the simulation. The time parameter permits the

Albert D. Sheffer; J. Michael Cathcart; John M. Stewart

1993-01-01

409

Modeling and simulation of count data.  

PubMed

Count data, or number of events per time interval, are discrete data arising from repeated time to event observations. Their mean count, or piecewise constant event rate, can be evaluated by discrete probability distributions from the Poisson model family. Clinical trial data characterization often involves population count analysis. This tutorial presents the basics and diagnostics of count modeling and simulation in the context of pharmacometrics. Consideration is given to overdispersion, underdispersion, autocorrelation, and inhomogeneity. PMID:25116273

Plan, E L

2014-01-01

410

System-Level Simulation Modeling with MLDesigner  

Microsoft Academic Search

System-level design presents special simulation modeling challenges. System-level models address the architectural and functional performance of complex systems. Systems are decomposed into a series of interacting sub-systems. Architectures define subsystems, the interconnections between subsystems and contention for shared resources. Functions define the input and output behavior of subsystems. Mission-level studies explore system performance in the context of mission-level scenarios. This

Gunar Schorcht; Ian A. Troxel; Keyvan Farhangian; Peter Unger; Daniel Zinn; Colin K. Mick; Alan D. George; Horst Salzwedel

2003-01-01

411

Optimizing simulation models of agricultural systems  

Microsoft Academic Search

Agricultural systems vary widely in terms of scale, scope and purpose. Managers of thesereal-world systems are typically faced\\u000a with a multitude of alternative management optionsand strategies, and are turning more towards simulation models in an attempt\\u000a to evaluatethese and identify the optimal combination. From a modelling perspective, agriculturalsystems present a range of\\u000a problems which need to be addressed, and these

D. G. Mayer; J. A. Belward; K. Burrage

1998-01-01

412

Safety evaluation using behavioral simulation models  

Microsoft Academic Search

This paper describes a design environment called ADEPT (advanced design environment prototype tool) which enables designers to assess the dependability of systems early in the design process using behavioral simulation models. ADEPT is an interactive graphical design environment which allows design and analysis of systems throughout the entire design cycle. ADEPT supports functional verification, performance evaluation, and dependability analysis early

Anup K. Ghosh; Barry W. Johnson; Joseph A. Profeta

1996-01-01

413

Center for Advanced Modeling and Simulation Intern  

SciTech Connect

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.

Gertman, Vanessa

2010-01-01

414

Love Kills:. Simulations in Penna Ageing Model  

NASA Astrophysics Data System (ADS)

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.

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

415

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...

416

Models, Simulations, and Games: A Survey.  

ERIC Educational Resources Information Center

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…

Shubik, Martin; Brewer, Garry D.

417

Center for Advanced Modeling and Simulation Intern  

ScienceCinema

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.

Gertman, Vanessa

2013-05-28

418

Adaptive System Modeling for Spacecraft Simulation  

NASA Technical Reports Server (NTRS)

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).

Thomas, Justin

2011-01-01

419

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

Microsoft Academic Search

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

Tian Shi; Roderic Gill

2005-01-01

420

Computational Spectrum of Agent Model Simulation  

SciTech Connect

The study of human social behavioral systems is finding renewed interest in military, homeland security and other applications. Simulation is the most generally applied approach to studying complex scenarios in such systems. Here, we outline some of the important considerations that underlie the computational aspects of simulation-based study of human social systems. The fundamental imprecision underlying questions and answers in social science makes it necessary to carefully distinguish among different simulation problem classes and to identify the most pertinent set of computational dimensions associated with those classes. We identify a few such classes and present their computational implications. The focus is then shifted to the most challenging combinations in the computational spectrum, namely, large-scale entity counts at moderate to high levels of fidelity. Recent developments in furthering the state-of-the-art in these challenging cases are outlined. A case study of large-scale agent simulation is provided in simulating large numbers (millions) of social entities at real-time speeds on inexpensive hardware. Recent computational results are identified that highlight the potential of modern high-end computing platforms to push the envelope with respect to speed, scale and fidelity of social system simulations. Finally, the problem of shielding the modeler or domain expert from the complex computational aspects is discussed and a few potential solution approaches are identified.

Perumalla, Kalyan S [ORNL

2010-01-01

421

Model Validation of Power System Components Using Hybrid Dynamic Simulation  

Microsoft Academic Search

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

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

2006-01-01

422

Electronic continuum model for molecular dynamics simulations  

NASA Astrophysics Data System (ADS)

A simple model for accounting for electronic polarization in molecular dynamics (MD) simulations is discussed. In this model, called molecular dynamics electronic continuum (MDEC), the electronic polarization is treated explicitly in terms of the electronic continuum (EC) approximation, while the nuclear dynamics is described with a fixed-charge force field. In such a force-field all atomic charges are scaled to reflect the screening effect by the electronic continuum. The MDEC model is rather similar but not equivalent to the standard nonpolarizable force-fields; the differences are discussed. Of our particular interest is the calculation of the electrostatic part of solvation energy using standard nonpolarizable MD simulations. In a low-dielectric environment, such as protein, the standard MD approach produces qualitatively wrong results. The difficulty is in mistreatment of the electronic polarizability. We show how the results can be much improved using the MDEC approach. We also show how the dielectric constant of the medium obtained in a MD simulation with nonpolarizable force-field is related to the static (total) dielectric constant, which includes both the nuclear and electronic relaxation effects. Using the MDEC model, we discuss recent calculations of dielectric constants of alcohols and alkanes, and show that the MDEC results are comparable with those obtained with the polarizable Drude oscillator model. The applicability of the method to calculations of dielectric properties of proteins is discussed.

Leontyev, I. V.; Stuchebrukhov, A. A.

2009-02-01

423

Electronic continuum model for molecular dynamics simulations.  

PubMed

A simple model for accounting for electronic polarization in molecular dynamics (MD) simulations is discussed. In this model, called molecular dynamics electronic continuum (MDEC), the electronic polarization is treated explicitly in terms of the electronic continuum (EC) approximation, while the nuclear dynamics is described with a fixed-charge force field. In such a force-field all atomic charges are scaled to reflect the screening effect by the electronic continuum. The MDEC model is rather similar but not equivalent to the standard nonpolarizable force-fields; the differences are discussed. Of our particular interest is the calculation of the electrostatic part of solvation energy using standard nonpolarizable MD simulations. In a low-dielectric environment, such as protein, the standard MD approach produces qualitatively wrong results. The difficulty is in mistreatment of the electronic polarizability. We show how the results can be much improved using the MDEC approach. We also show how the dielectric constant of the medium obtained in a MD simulation with nonpolarizable force-field is related to the static (total) dielectric constant, which includes both the nuclear and electronic relaxation effects. Using the MDEC model, we discuss recent calculations of dielectric constants of alcohols and alkanes, and show that the MDEC results are comparable with those obtained with the polarizable Drude oscillator model. The applicability of the method to calculations of dielectric properties of proteins is discussed. PMID:19256627

Leontyev, I V; Stuchebrukhov, A A

2009-02-28

424

Fault diagnosis based on continuous simulation models  

NASA Technical Reports Server (NTRS)

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.

Feyock, Stefan

1987-01-01

425

Atmospheric Modeling And Sensor Simulation (AMASS) study  

NASA Technical Reports Server (NTRS)

The capabilities of the atmospheric modeling and sensor simulation (AMASS) system were studied in order to enhance them. This system is used in processing atmospheric measurements which are utilized in the evaluation of sensor performance, conducting design-concept simulation studies, and also in the modeling of the physical and dynamical nature of atmospheric processes. The study tasks proposed in order to both enhance the AMASS system utilization and to integrate the AMASS system with other existing equipment to facilitate the analysis of data for modeling and image processing are enumerated. The following array processors were evaluated for anticipated effectiveness and/or improvements in throughput by attachment of the device to the P-e: (1) Floating Point Systems AP-120B; (2) Floating Point Systems 5000; (3) CSP, Inc. MAP-400; (4) Analogic AP500; (5) Numerix MARS-432; and (6) Star Technologies, Inc. ST-100.

Parker, K. G.

1984-01-01

426

Flight Simulation Model Exchange. Volume 1  

NASA Technical Reports Server (NTRS)

The NASA Engineering and Safety Center Review Board sponsored an assessment of the draft Standard, Flight Dynamics Model Exchange Standard, BSR/ANSI-S-119-201x (S-119) that was conducted by simulation and guidance, navigation, and control engineers from several NASA Centers. The assessment team reviewed the conventions and formats spelled out in the draft Standard and the actual implementation of two example aerodynamic models (a subsonic F-16 and the HL-20 lifting body) encoded in the Extensible Markup Language grammar. During the implementation, the team kept records of lessons learned and provided feedback to the American Institute of Aeronautics and Astronautics Modeling and Simulation Technical Committee representative. This document contains the results of the assessment.

Murri, Daniel G.; Jackson, E. Bruce

2011-01-01

427

A Superbubble Feedback Model for Galaxy Simulations  

E-print Network

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, sub-grid evaporation and a sub-grid multi-phase treatment for cases where the simulation mass resolution is insufficient to model the early stages of the superbubble. The multi-phase 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 ISM below $10^6$ 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 ...

Keller, B W; Benincasa, S M; Couchman, H M P

2014-01-01

428

Flight Simulation Model Exchange. Volume 2; Appendices  

NASA Technical Reports Server (NTRS)

The NASA Engineering and Safety Center Review Board sponsored an assessment of the draft Standard, Flight Dynamics Model Exchange Standard, BSR/ANSI-S-119-201x (S-119) that was conducted by simulation and guidance, navigation, and control engineers from several NASA Centers. The assessment team reviewed the conventions and formats spelled out in the draft Standard and the actual implementation of two example aerodynamic models (a subsonic F-16 and the HL-20 lifting body) encoded in the Extensible Markup Language grammar. During the implementation, the team kept records of lessons learned and provided feedback to the American Institute of Aeronautics and Astronautics Modeling and Simulation Technical Committee representative. This document contains the appendices to the main report.

Murri, Daniel G.; Jackson, E. Bruce

2011-01-01

429

Testing a Social Ecological Model for Relations between Political Violence and Child Adjustment in Northern Ireland  

PubMed Central

Relations between political violence and child adjustment are matters of international concern. Past research demonstrates the significance of community, family and child psychological processes in child adjustment, supporting study of inter-relations between multiple social ecological factors and child adjustment in contexts of political violence. Testing a social ecological model, 300 mothers and their children (M= 12.28 years, SD = 1.77) from Catholic and Protestant working class neighborhoods in Belfast, Northern Ireland completed measures of community discord, family relations, and children’s regulatory processes (i.e., emotional security) and outcomes. Historical political violence in neighborhoods based on objective records (i.e., politically motivated deaths) were related to family members’ reports of current sectarian and non-sectarian antisocial behavior. Interparental conflict and parental monitoring and children’s emotional security about both the community and family contributed to explanatory pathways for relations between sectarian antisocial behavior in communities and children’s adjustment problems. The discussion evaluates support for social ecological models for relations between political violence and child adjustment and its implications for understanding relations in other parts of the world. PMID:20423550

Cummings, E. Mark; Merrilees, Christine E.; Schermerhorn, Alice C.; Goeke-Morey, Marcie C.; Shirlow, Peter; Cairns, Ed

2013-01-01

430

Development and Application of a Component-based Generic Farm System Simulator Implementing a Semantically Enriched Integrated Modelling Framework  

Microsoft Academic Search

In this paper, the software development and test applications of a component-based generic farm system simulator is presented. The Farm System Simulator (FSSIM) developed within the EU FP6 SEAMLESS project (www.seamless-ip.org) is an integrated modelling system developed to assess the economic and ecological impacts of agricultural and environmental policies and technological innovations. Based on the semantic link of biophysical and

Hongtao Li; Kamel Louhichi; Sander Janssen; Andrea Emilio Rizzoli; Ioannis Athanasiadis; Eelco Meuter; David Huber

431

Integrated Modeling for the Assessment of Ecological Impacts of Sea Level Rise  

NASA Astrophysics Data System (ADS)

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.

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

432

Spatial modeling of ecological areas by fitting the limiting factors for As in the vicinity of mine, Serbia.  

PubMed

Elevated arsenic (As) concentrations in soil are often found in the vicinity of certain mineral deposits that have been, or are currently, under exploitation, regardless of the target resource. Detailed study of such areas for safe agriculture requires considerable financial costs and long periods of time. Application of an appropriate spatial model that describes the behavior of arsenic in soil and plants can significantly ease the whole investigation process. This paper presents a model of ecological security of an area that, in the past, was an antimony mine and has a naturally high content of arsenic. For simulation and modeling the geographic information science (GIS) technology with the inserted predictors influencing the accessibility of As and its content in plants was used. The results obtained were the following: (1) a categorization of contaminated soils according to soil properties was developed; (2) the proposed methodology allows focusing on particular suspect area saving an energy and human resource input; and (3) new safe areas for growing crops in contaminated area were modeled. The application of the proposed model of As solubility to various crops grown around a former antimony mine near the village of Lisa, southwest Serbia showed that significant expansion of the areas suitable for growing potato, raspberry, and pasture was possible. PMID:24281676

Cakmak, Dragan; Perovic, Veljko; Saljnikov, Elmira; Jaramaz, Darko; Sikiric, Biljana

2014-03-01

433

Dynamics modeling and simulation of flexible airships  

NASA Astrophysics Data System (ADS)

The resurgence of airships has created a need for dynamics models and simulation capabilities of these lighter-than-air vehicles. The focus of this thesis is a theoretical framework that integrates the flight dynamics, structural dynamics, aerostatics and aerodynamics of flexible airships. The study begins with a dynamics model based on a rigid-body assumption. A comprehensive computation of aerodynamic effects is presented, where the aerodynamic forces and moments are categorized into various terms based on different physical effects. A series of prediction approaches for different aerodynamic effects are unified and applied to airships. The numerical results of aerodynamic derivatives and the simulated responses to control surface deflection inputs are verified by comparing to existing wind-tunnel and flight test data. With the validated aerodynamics and rigid-body modeling, the equations of motion of an elastic airship are derived by the Lagrangian formulation. The airship is modeled as a free-free Euler-Bernoulli beam and the bending deformations are represented by shape functions chosen as the free-free normal modes. In order to capture the coupling between the aerodynamic forces and the structural elasticity, local velocity on the deformed vehicle is used in the computation of aerodynamic forces. Finally, with the inertial, gravity, aerostatic and control forces incorporated, the dynamics model of a flexible airship is represented by a single set of nonlinear ordinary differential equations. The proposed model is implemented as a dynamics simulation program to analyze the dynamics characteristics of the Skyship-500 airship. Simulation results are presented to demonstrate the influence of structural deformation on the aerodynamic forces and the dynamics behavior of the airship. The nonlinear equations of motion are linearized numerically for the purpose of frequency domain analysis and for aeroelastic stability analysis. The results from the latter for the Skyship-500 airship indicate that this vehicle is not susceptible to aeroelastic instability in its operating range. However, these problems may arise for modern airship designs with thin film materials.

Li, Yuwen

434

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 ...

435

Modelling the Ecological Vulnerability to Forest Fires in Mediterranean Ecosystems Using Geographic Information Technologies  

NASA Astrophysics Data System (ADS)

Forest fires represent a major driver of change at the ecosystem and landscape levels in the Mediterranean region. Environmental features and vegetation are key factors to estimate the ecological vulnerability to fire; defined as the degree to which an ecosystem is susceptible to, and unable to cope with, adverse effects of fire (provided a fire occurs). Given the predicted climatic changes for the region, it is urgent to validate spatially explicit tools for assessing this vulnerability in order to support the design of new fire prevention and restoration strategies. This work presents an innovative GIS-based modelling approach to evaluate the ecological vulnerability to fire of an ecosystem, considering its main components (soil and vegetation) and different time scales. The evaluation was structured in three stages: short-term (focussed on soil degradation risk), medium-term (focussed on changes in vegetation), and coupling of the short- and medium-term vulnerabilities. The model was implemented in two regions: Aragón (inland North-eastern Spain) and Valencia (eastern Spain). Maps of the ecological vulnerability to fire were produced at a regional scale. We partially validated the model in a study site combining two complementary approaches that focused on testing the adequacy of model's predictions in three ecosystems, all very common in fire-prone landscapes of eastern Spain: two shrublands and a pine forest. Both approaches were based on the comparison of model's predictions with values of NDVI (Normalized Difference Vegetation Index), which is considered a good proxy for green biomass. Both methods showed that the model's performance is satisfactory when applied to the three selected vegetation types.

Duguy, Beatriz; Alloza, José Antonio; Baeza, M. Jaime; De la Riva, Juan; Echeverría, Maite; Ibarra, Paloma; Llovet, Juan; Cabello, Fernando Pérez; Rovira, Pere; Vallejo, Ramon V.

2012-12-01

436

A SIMULATION MODEL FOR CANADA-US CLIMATE POLICY ANALYSIS  

E-print Network

A SIMULATION MODEL FOR CANADA-US CLIMATE POLICY ANALYSIS by William J. Tubbs BSc. (Hon: A Simulation Model for Canada-US Climate Policy Analysis Project No.: 457 Examining Committee: Chair: Suzanne the integration of bottom-up technology models and top-down macroeconomic models. A simulation model of the energy

437

Macro Level Simulation Model Of Space Shuttle Processing  

NASA Technical Reports Server (NTRS)

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.

2000-01-01

438

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

NASA Technical Reports Server (NTRS)

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.

Antonsson, Erik; Gombosi, Tamas

2005-01-01

439

MODELLING AND SIMULATING PROCESS-ORIENTED KNOWLEDGE MANAGEMENT  

E-print Network

MODELLING AND SIMULATING PROCESS-ORIENTED KNOWLEDGE MANAGEMENT Irina Shostak¹, Anjo Anjewierden. Simulating those models becomes very valuable when one wants to investigate different knowledge management scenarios. Key words: process-oriented knowledge management, knowledge management business model

Anjewierden, Anjo

440

Optimisation Strategies for Modelling and Simulation  

NASA Astrophysics Data System (ADS)

Progress in computation techniques has been dramatically reducing the gap between modeling and simulation. Simulation as the natural outcome of modeling is used both as a tool to predict the behavior of natural or artificial systems, a tool to validate modeling, and a tool to build and refine models - in particular identify model internal parameters. In this paper we will concentrate upon the latter, model building and identification, using modern optimization techniques, through application examples taken from the digital imaging field. The first example is given by Image Processing with retrieval of known patterns in an image. The second example is taken from synthetic image animation: we show how it is possible to learn the model's internal physical parameters from actual trajectory examples, using Darwin-inspired evolutionary algorithms. In the third example, we will demonstrate how it is possible, when the problem cannot easily be handled by a reasonably simple optimization technique, to split the problem into simpler elements which can be efficiently evolved by an evolutionary optimization algorithm - which is now called "Parisian Evolution". The "Fly algorithm" is a realtime stereovision algorithm which skips conventional preliminary stages of image processing, now applied into mobile robotics and medical imaging. The main question left is now, to which degree is it possible to delegate to a computer a part of the physicist's role, which is to collect examples and build general laws from these examples?

Louchet, Jean

2007-12-01

441

Towards Better Coupling of Hydrological Simulation Models  

NASA Astrophysics Data System (ADS)

Standards for model interoperability and scientific workflow software provide techniques and tools for coupling hydrological simulation models. However, model builders are yet to realize the benefits of these and continue to write ad hoc implementations and scripts. Three case studies demonstrate different approaches to coupling models, the first using tight interfaces (OpenMI), the second using a scientific workflow system (Trident) and the third using a tailored execution engine (Delft Flood Early Warning System - Delft-FEWS). No approach was objectively better than any other approach. The foremost standard for coupling hydrological models is the Open Modeling Interface (OpenMI), which defines interfaces for models to interact. An implementation of the OpenMI standard involves defining interchange terms and writing a .NET/Java wrapper around the model. An execution wrapper such as OatC.GUI or Pipistrelle executes the models. The team built two OpenMI implementations for eWater Source river system models. Once built, it was easy to swap river system models. The team encountered technical challenges with versions of the .Net framework (3.5 calling 4.0) and with the performance of the execution wrappers when running daily simulations. By design, the OpenMI interfaces are general, leaving significant decisions around the semantics of the interfaces to the implementer. Increasingly, scientific workflow tools such as Kepler, Taverna and Trident are able to replace custom scripts. These tools aim to improve the provenance and reproducibility of processing tasks. In particular, Taverna and the myExperiment website have had success making many bioinformatics workflows reusable and sharable. The team constructed Trident activities for hydrological software including IQQM, REALM and eWater Source. They built an activity generator for model builders to build activities for particular river systems. The models were linked at a simulation level, without any daily time-step feedbacks. There was no obvious way to add daily time-step feedbacks without incurring a considerable performance penalty. The Delft-FEWS system connects hydrological models for flood warnings and forecasts in a workflow system. It provides a range of custom facilities for connecting real-time data services. A Delft-FEWS system was constructed to connect a series of eWater Source hydrological models using the batch forecast mode to orchestrate a time-stepping system. The system coupled a series of river models running daily through a service interface. The implementation did not easily support interoperability with other models; however, using command line calls and the file-system did allow a level of language independence. The case-studies covered the coupling of hydrological models through tight interfaces (OpenMI), broad scientific workflow software (Trident) and a tailored execution engine (Delft-FEWS). We found that no approach was objectively better than any other approach. OpenMI had the most flexible interfaces, Trident the best handling of provenance and Delft-FEWS provided a significant set of tools for ingesting and transforming data. The case studies revealed a need for stable execution wrappers, patterns for efficient cross-language interoperability, targeted semantics for hydrological simulation and better handling of daily simulation.

Penton, D.; Stenson, M.; Leighton, B.; Bridgart, R.

2012-12-01

442

Computational ecology as an emerging science  

PubMed Central

It has long been recognized that numerical modelling and computer simulations can be used as a powerful research tool to understand, and sometimes to predict, the tendencies and peculiarities in the dynamics of populations and ecosystems. It has been, however, much less appreciated that the context of modelling and simulations in ecology is essentially different from those that normally exist in other natural sciences. In our paper, we review the computational challenges arising in modern ecology in the spirit of computational mathematics, i.e. with our main focus on the choice and use of adequate numerical methods. Somewhat paradoxically, the complexity of ecological problems does not always require the use of complex computational methods. This paradox, however, can be easily resolved if we recall that application of sophisticated computational methods usually requires clear and unambiguous mathematical problem statement as well as clearly defined benchmark information for model validation. At the same time, many ecological problems still do not have mathematically accurate and unambiguous description, and available field data are often very noisy, and hence it can be hard to understand how the results of computations should be interpreted from the ecological viewpoint. In this scientific context, computational ecology has to deal with a new paradigm: conventional issues of numerical modelling such as convergence and stability become less important than the qualitative analysis that can be provided with the help of computational techniques. We discuss this paradigm by considering computational challenges arising in several specific ecological applications. PMID:23565336

Petrovskii, Sergei; Petrovskaya, Natalia

2012-01-01

443

Ocean background model for scene simulation  

NASA Astrophysics Data System (ADS)

An ocean surface model for synthetic IR/visible imaging applications has been developed at GTRI based upon the Pierson-Moskowitz wave spectrum. The model calculates a 2D grid of height values describing a given snapshot of the sea surface. This surface is a function of wind speed and direction as well as elapsed time into the simulation. The time parameter permits the animation of the sea surface during a simulated movie sequence. Sea signatures are calculated using a combination of models and tools: the GTRI IR signature code GTSIG is used to predict sea temperatures; LOWTRAN7 is used to construct tables of sky radiances; the Fresnel equations are used to construct tables of sea reflectance. These signature components are combined during image rendering with a ray-tracing approach the provides the total radiance (emitted and reflected) from the ocean surface arriving at each sensor image pixel. This ocean model has been integrated into a complete image rendering system called GTRENDER, and is available for use in GTRI applications such as the GTSIMS family of missile simulations.

Sheffer, Albert D., Jr.; Cathcart, J. Michael; Stewart, John M.

1993-11-01

444

Modeling and simulation of the human eye  

NASA Astrophysics Data System (ADS)

The computational modeling of the human eye has been wide studied for different sectors of the scientific and technological community. One of the main reasons for this increasing interest is the possibility to reproduce eye optic properties by means of computational simulations, becoming possible the development of efficient devices to treat and to correct the problems of the vision. This work explores this aspect still little investigated of the modeling of the visual system, considering a computational sketch that make possible the use of real data in the modeling and simulation of the human visual system. This new approach makes possible the individual inquiry of the optic system, assisting in the construction of new techniques used to infer vital data in medical investigations. Using corneal topography to collect real data from patients, a computational model of cornea is constructed and a set of simulations were build to ensure the correctness of the system and to investigate the effect of corneal abnormalities in retinal image formation, such as Plcido Discs, Point Spread Function, Wave front and the projection of a real image and it's visualization on retina.

Duran, R.; Ventura, L.; Nonato, L.; Bruno, O.

2007-02-01

445

eShopper modeling and simulation  

NASA Astrophysics Data System (ADS)

The advent of e-commerce gives an opportunity to shift the paradigm of customer communication into a highly interactive mode. The new generation of commercial Web servers, such as the Blue Martini's server, combines the collection of data on a customer behavior with real-time processing and dynamic tailoring of a feedback page. The new opportunities for direct product marketing and cross selling are arriving. The key problem is what kind of information do we need to achieve these goals, or in other words, how do we model the customer? The paper is devoted to customer modeling and simulation. The focus is on modeling an individual customer. The model is based on the customer's transaction data, click stream data, and demographics. The model includes the hierarchical profile of a customer's preferences to different types of products and brands; consumption models for the different types of products; the current focus, trends, and stochastic models for time intervals between purchases; product affinity models; and some generalized features, such as purchasing power, sensitivity to advertising, price sensitivity, etc. This type of model is used for predicting the date of the next visit, overall spending, and spending for different types of products and brands. For some type of stores (for example, a supermarket) and stable customers, it is possible to forecast the shopping lists rather accurately. The forecasting techniques are discussed. The forecasting results can be used for on- line direct marketing, customer retention, and inventory management. The customer model can also be used as a generative model for simulating the customer's purchasing behavior in different situations and for estimating customer's features.

Petrushin, Valery A.

2001-03-01

446

Theory, modeling and simulation: Annual report 1993  

SciTech Connect

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.

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

1994-07-01

447

Ecology and evolution simulation and quest design for an educational massive multiplayer online game  

E-print Network

In this design-based research project, I developed two simulations to be used as student tools in a massively multiplayer online game targeted at STEM education, the Radix Endeavor. I designed both the underlying agent-based ...

Zhang, Mark (Mark A.)

2013-01-01

448

Simulation of model swimmers near ciliated surfaces  

NASA Astrophysics Data System (ADS)

Biofouling by micro-organisms is problematic on scales from microfluidic devices to the largest ships in the ocean. One solution found in nature for clearing undesired material from surfaces is to employ active cilia, for example, in the respiratory tract. It is feasible to fabricate surfaces covered with artificial cilia actuated by an externally imposed field. Using numerical simulation, we investigate the interactions between these artificial cilia and self-propelled model swimmers. One of the key aims is to explore the possibility of steering swimmers to influence their trajectories through the flow field produced by the cilia. In our simulations, the fluid dynamics is solved using the lattice Boltzmann method while the cilia and model swimmers are governed by elastic internal mechanics. We implement an immersed boundary approach to couple the solid and fluid dynamics.

Shum, Henry; Tripathi, Anurag; Yeomans, Julia; Balazs, Anna

2013-03-01

449

Integration of modeling components into ecological and human health risk assessments  

SciTech Connect

The Hudson River is an important recreational and ecological resource in New York State. From 1957 to 1975 between 209,000 and 1.3 million pounds of polychlorinated biphenyls (PCBs) were discharged into the Hudson River from two electrical capacitor manufacturing facilities. Many PCBs discharged to the river adhered to the sediment in the Upper River. Aquatic organisms have been exposed to PCBs in the sediment through ingestion or direct contact with sediment. PCBs in the sediment can enter the water column via particulate resuspension and dissolved PCB diffusion from sediment pore water to the overlying water column, providing additional exposure pathways. Multiple exposure pathways can increase the body burden of organisms living in contaminated areas. Ecological and human health risk assessments are being performed as part of a reassessment effort to determine the need and extent of remediation, required for contaminated sediments in the Upper River. Hydrodynamic, water quality and food-chain models based upon and calibrated to recent and historical data collection efforts are integrated into the risk assessments to provide estimates of total PCBs, Aroclors and selected congener concentrations at specific locations in the river under current and future scenarios. The results of both the ecological and human health risk assessments will assist in defining PCB concentrations that pose risks to the biological communities of the Hudson River.

Chernoff, H.; Tomchuk, D. [TAMS Consultants, Inc., Boston, MA (United States)

1995-12-31

450

Development of a conceptual model for ecological risk assessment in the Clinch River, VA  

SciTech Connect

The Clinch River watershed is one of five selected by the USEPA to: (1) evaluate the methodology given in the USEPA Framework for Ecological Risk Assessment, and (2) provide a case study with which to develop an ecological risk problem formulation framework given a complex watershed with multiple stressors. The Clinch water is perhaps most notable for its high diversity of endemic mussel and fish species, most of which are threatened and endangered. Discussions among most of the resource managers in the watershed revealed four assessment endpoints for this risk assessment, all of which have ecological and societal value, and which are susceptible to a number of stressors common in the recruitment and reproduction; threatened and endangered mussel species recruitment and reproduction; threatened and endangered fish species recruitment and reproduction; aquatic cave fauna abundance and diversity; and riparian corridor extent, connectivity, and species composition. Together, these endpoints address the goals established by the workgroup: self-sustaining populations of native macroinvertebrates and fish; improving surface and subsurface water quality; and establishing and maintaining functional riparian corridors of native vegetation. The heart of the problem formulation was defining the conceptual model for this system. Several sources were addressed including various anthropogenic land-use activities, introduced species, and acid rain.

Diamond, J.; Miller, J.

1995-12-31

451

Ecological input-output modeling for embodied resources and emissions in Chinese economy 2005  

NASA Astrophysics Data System (ADS)

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.

Chen, Z. M.; Chen, G. Q.; Zhou, J. B.; Jiang, M. M.; Chen, B.

2010-07-01

452

At the Biological Modeling and Simulation Frontier  

Microsoft Academic Search

We provide a rationale for and describe examples of synthetic modeling and simulation (M&S) of biological systems. We explain\\u000a how synthetic methods are distinct from familiar inductive methods. Synthetic M&S is a means to better understand the mechanisms\\u000a that generate normal and disease-related phenomena observed in research, and how compounds of interest interact with them\\u000a to alter phenomena. An objective

C. Anthony Hunt; Glen E. P. Ropella; Tai Ning Lam; Jonathan Tang; Sean H. J. Kim; Jesse A. Engelberg; Shahab Sheikh-Bahaei

2009-01-01

453

Simulation of Advanced Transaction Models Using GOLOG  

Microsoft Academic Search

We propose a logical framework for describing, reasoning about, and simulating transaction mod- els that relax some of the ACID (Atomicity-Consistency-Isolation-Durability) properties of classi- cal transactions. Such extensions, usually called advanced transaction models (ATMs), have been proposed for dealing with new database applications involving long-lived, endless, and cooperative activities. Our approach appeals to non-Markovian theories, in which one may refer

Iluju Kiringa

2001-01-01

454

Coupled map lattice approximations for spatially explicit individual-based models of ecology.  

PubMed

Spatially explicit individual-based models are widely used in ecology but they are often difficult to treat analytically. Despite their intractability they often exhibit clear temporal and spatial patterning. We demonstrate how a spatially explicit individual-based model of scramble competition with local dispersal can be approximated by a stochastic coupled map lattice. The approximation disentangles the deterministic and stochastic element of local interaction and dispersal. We are thus able to understand the individual-based model through a simplified set of equations. In particular, we demonstrate that demographic noise leads to increased stability in the dynamics of locally dispersing single-species populations. The coupled map lattice approximation has general application to a range of spatially explicit individual-based models. It provides a new alternative to current approximation techniques, such as the method of moments and reaction-diffusion approximation, that captures both stochastic effects and large-scale patterning arising in individual-based models. PMID:15893547

Brännström, A; Sumpter, D J T

2005-07-01

455

Postglacial species displacement in Triturus newts deduced from asymmetrically introgressed mitochondrial DNA and ecological niche models  

PubMed Central

Background If the geographical displacement of one species by another is accompanied by hybridization, mitochondrial DNA can introgress asymmetrically, from the outcompeted species into the invading species, over a large area. We explore this phenomenon using the two parapatric crested newt species, Triturus macedonicus and T. karelinii, distributed on the Balkan Peninsula in south-eastern Europe, as a model. Results We first delimit a ca. 54,000?km2 area in which T. macedonicus contains T. karelinii mitochondrial DNA. This introgression zone bisects the range of T. karelinii, cutting off a T. karelinii enclave. The high similarity of introgressed mitochondrial DNA haplotypes with those found in T. karelinii suggests a recent transfer across the species boundary. We then use ecological niche modeling to explore habitat suitability of the location of the present day introgression zone under current, mid-Holocene and Last Glacial Maximum conditions. This area was inhospitable during the Last Glacial Maximum for both species, but would have been habitable at the mid-Holocene. Since the mid-Holocene, ha