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1

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

Microsoft Academic Search

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

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

2005-01-01

2

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...

3

Simulation Models for Potato Late Blight Management and Ecology  

Microsoft Academic Search

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

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

4

Simulating pesticides in ditches to assess ecological risk (SPIDER): I. Model description.  

PubMed

Risk assessment for pesticides in the aquatic environment relies on a comparison between estimated exposure concentrations in surface water bodies and endpoints from a series of effect tests. Many field- and catchment-scale models have been developed, ranging from simple empirical models to comprehensive, physically-based, distributed models that require complex parameterisation, often through inverse modelling methods. Routine use of catchment models for assessment and management of pesticides requires a tool that is comprehensive in being able to address all major routes of entry of pesticides into surface water and that has reasonable parameter requirements. Current models either focus primarily on transport of pesticides in surface runoff or are restricted in application because they require calibration against data from detailed monitoring programmes. SPIDER (Simulating Pesticides In Ditches to assess Ecological Risk) was developed to address the gap in models available to simulate pesticide exposure within networks of small surface water bodies (ditches and streams) in support of ecological risk assessment for pesticides. SPIDER is a locally distributed, capacitance-based model that accounts for pesticide entry into surface water bodies via spray drift, surface runoff, interlayer flow and drainflow and that can be used for small agricultural catchments. This paper provides a detailed description of the model. PMID:18275984

Renaud, Fabrice G; Bellamy, Pat H; Brown, Colin D

2008-05-01

5

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...

6

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

7

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

PubMed

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

Krick, Julian; Ackerman, Josef Daniel

2015-03-01

8

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

9

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

10

Simulating pesticides in ditches to assess ecological risk (SPIDER): II. Benchmarking for the drainage model.  

PubMed

SPIDER (simulating pesticides in ditches to assess ecological risk) is a locally distributed, capacitance-based model that accounts for pesticide entry into surface water bodies via spray drift, surface runoff, interlayer flow and drainage. SPIDER was developed for application to small agricultural catchments. Transport of pesticide from site of application to surface water via subsurface field drains is one of the major routes of entry to surface water. Several pesticide fate models describe transfer of pesticide via drainflow, notably MACRO which has been evaluated against field data in several studies. The capacity of SPIDER to simulate drainflow and pesticide concentration in drain water was evaluated against two datasets that had been used previously to evaluate MACRO independently of this study: a plot experiment at Cockle Park and a field experiment at Maidwell, both located in the UK. In both circumstances, SPIDER was able to reproduce drain hydrographs relatively well with no or limited calibration. At Cockle Park, simulated and observed drainflow over the season were 240 and 278 mm, respectively with a Nash and Sutcliffe model efficiency (NSME) coefficient of 0.32 whilst at Maidwell they were 259 and 296 mm, respectively with a NSME coefficient of 0.55. Prediction of maximum isoproturon concentration at Cockle Park by SPIDER and MACRO were 5.3 and 13.1 microg L(- 1) respectively compared to the 3.8 microg L(- 1) measured in the field, whilst pesticide load to drains over the season were 0.22 and 1.53 g, respectively, compared to an observed load of 0.35 g. Maximum sulfosulfuron concentration at Maidwell were 2.3, 3.9 and 5.4 microg L(- 1) for observed and as simulated by SPIDER and MACRO, respectively and pesticide loading to drains of the season was 0.77, 5.61, 4.77 g, respectively. Results from the sensitivity analysis showed that the sensitivity of SPIDER compared favourably to that of several other capacity models but was more sensitive than MACRO to variations in input parameters. SPIDER is currently being tested at the catchment scale. PMID:18280538

Renaud, Fabrice G; Brown, Colin D

2008-05-01

11

A Simulated Stream Ecology Study.  

ERIC Educational Resources Information Center

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

Zampella, Robert A.

1979-01-01

12

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

13

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

14

Individual-based models as tools for ecological theory and application: Understanding the emergence of organisational properties in ecological systems  

Microsoft Academic Search

Individual-based models offer a structurally unique (and unifying) approach to ecological applications. Model results also provide an important input into ecological theory. The approach operates on the lowest organisational level considered in ecology (i.e. activities of individuals). Simulating the actions of single organisms allows to study how the properties of higher level ecological entities like swarms, populations, trophic networks and

Broder Breckling; Ulrike Middelhoff; Hauke Reuter

2006-01-01

15

Ecological reality and model validation  

SciTech Connect

Definitions of model realism and model validation are developed. Ecological and mathematical arguments are then presented to show that model equations which explicitly treat ecosystem processes can be systematically improved such that greater realism is attained and the condition of validity is approached. Several examples are presented.

Cale, Jr, W. G.; Shugart, H. H.

1980-01-01

16

Effects of changing anthropogenic pressures on water quality and plankton dynamics in three Swiss lakes - Long-term simulations with the biogeochemical-ecological lake model BELAMO  

Microsoft Academic Search

Water quality and plankton dynamics, important indicators for the ecological state of a lake, are affected by many influence factors. To understand the behaviour of a lake under changing driving forces (such as nutrient loads or climatic change), modelling is an important resource. A model used for this purpose should represent the quantitative understanding of the dominant biogeochemical and ecological

A. Dietzel; J. Mieleitner; P. Reichert

2009-01-01

17

Effects of changing anthropogenic pressures on water quality and plankton dynamics in three Swiss lakes - Long-term simulations with the biogeochemical-ecological lake model BELAMO  

NASA Astrophysics Data System (ADS)

Water quality and plankton dynamics, important indicators for the ecological state of a lake, are affected by many influence factors. To understand the behaviour of a lake under changing driving forces (such as nutrient loads or climatic change), modelling is an important resource. A model used for this purpose should represent the quantitative understanding of the dominant biogeochemical and ecological processes within a lake and be as universal as possible. With the Biogeochemical Ecologial LAke MOdel (BELAMO) it was tried to combine the description of biogeochemical processes in the lake with an ecological model. The results of its application to the lakes Greifensee (eutrophic), Lake Zurich (mesotrophic) and Walensee (oligotrophic) indicate that already a relatively simple plankton sub-model can lead to a quite high degree of universality (in the sense of applicability of the same model and parameter values to lakes of different trophic state). The box version of the model distinguishes the four mixed compartments epilimnion, hypolimnion and 2 sediment layers. It aims at a joint calculation of mass balances of nutrients, oxygen, organic particles, one group of phytoplankton and one group of zooplankton in a lake in all four compartments. The model was designed to explicitly describe the sediment processes, instead of considering their effect by source and sink terms at the bottom of the lake for substances exchanged between lake water and the sediment. Therefore the different mineralisation processes had to be quantified. Difficulties compassed the identification of aerobic, anoxic and anaerobic mineralisation rates while representing jointly the measured concentrations of oxygen, nitrate and organic material in the lake. The description of the lake by mixed compartments enhanced this difficulty, because the depth of the sediment layers determines maximal diffusion gradients for the entry of substances into the sediment. One further problem we had to cope with was the availability of concentration data only. The same concentrations can result from different fluxes that drive the dynamics in the lake. Different concentrations can have quite different sensitivities to external changes. An example for this are phosphate and algae. While the phosphate concentration responds quite fast to a decrease in phosphate input loading, the algae might not show this decrease directly. This is due to the ability of adaptation of the algal community and a parallel reaction of zooplankton. For this reason, the reduced turnover rates of phosphate do not necessarily lead to much smaller plankton concentrations. On a shorter time scale, phytoplankton and zooplankton can show faster variability than can be detected by monthly data. This makes it impossible to get a realistic description of short-term algal dynamics. To handle this problem when improving the model we conducted parameter calibrations that fit smoothed model results to smoothed data. This calibration technique avoids fitting the model to uncertain data peaks as well as rejecting parameter combinations resulting in model outputs that do not represent individual data peaks, but cover the main patterns of the measurements correctly. This pattern fitting technique led to a much better performance of the fit algorithm than fitting to the original data, which often resulted in simulations that covered some data peaks, but missed the basic annual and long-term pattern. In the end, long-term simulations for 20-30 years (depending on data availability for the different lakes) showed that good simulations are possible despite significantly changing driving forces. This is an indication of the good mechanistic representation of the processes in the lake. Nevertheless, as this behaviour depends critically on the chosen model parameter values, the predictive power of the model still needs further improvement.

Dietzel, A.; Mieleitner, J.; Reichert, P.

2009-04-01

18

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.

19

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

20

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

21

Ecologic simulation of warm water aquaculture ponds  

SciTech Connect

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

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

1983-06-01

22

QUALITATIVE ECOLOGICAL MODELING  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

23

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

24

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 issue, which integrate ecological, human demographic, behavioral, social, and economic factors through

2001-01-01

25

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

26

Simulated coevolution in a mutating ecology  

NASA Astrophysics Data System (ADS)

The bit-string Penna model is used to simulate the competition between an asexual parthenogenetic and a sexual population sharing the same environment. A newborn of either population can mutate and become a part of the other with some probability. In a stable environment the sexual population soon dies out. When an infestation by rapidly mutating genetically coupled parasites is introduced, however, sexual reproduction prevails, as predicted by the so-called Red Queen hypothesis for the evolution of sex.

Sá Martins, J. S.

2000-03-01

27

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

28

DYNAMIC LANDSCAPES, STABILITY AND ECOLOGICAL MODELING  

EPA Science Inventory

The image of a ball rolling along a series of hills and valleys is an effective heuristic by which to communicate stability concepts in ecology. However, the dynamics of this landscape model have little to do with ecological systems. Other landscape representations, however, are ...

29

Spatial Autocorrelation and Autoregressive Models in Ecology  

Microsoft Academic Search

Recognition and analysis of spatial autocorrelation has defined a new par- adigm in ecology. Attention to spatial pattern can lead to insights that would have been otherwise overlooked, while ignoring space may lead to false conclusions about ecological relationships. We used Gaussian spatial autoregressive models, fit with widely available software, to examine breeding habitat relationships for three common Neotropical migrant

Jeremy W. Lichstein; Theodore R. Simons; Susan A. Shriner; Kathleen E. Franzreb

2002-01-01

30

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

E-print Network

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

Arhonditsis, George B.

2005-01-01

31

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

32

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

33

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

34

Ecological Modelling 250 (2013) 4557 Contents lists available at SciVerse ScienceDirect  

E-print Network

Ecological Modelling 250 (2013) 45­57 Contents lists available at SciVerse ScienceDirect Ecological cycling extension for the LANDIS-II landscape simulation model Sarah L. Karama, , Peter J. Weisberga and Environmental Science, University of Nevada, Mail Stop 186, 1000 Valley Road, Reno, NV 89512, USA b Department

Weisberg, Peter J.

35

Topology Matters: Network topology affects outcomes from community ecology neutral models  

E-print Network

Topology Matters: Network topology affects outcomes from community ecology neutral models Denis and the erratum in a single document. Abstract. Topology affects outcomes of processes in planar networks. Hexagon topology for neutral ecology community models, following the simulation approach of Graham Bell

Jenny, Bernhard

36

Simulating Biological Impairment to Evaluate the Accuracy of Ecological Indicators  

NASA Astrophysics Data System (ADS)

Environmental management depends on accurate monitoring and assessment of ecological conditions. Bioassessments are generally based on the measurement of selected indicators. However, the accuracy of these indicators is difficult to evaluate because the true biological impairment of a system is almost always unknown. We describe a simulation procedure that allows objective comparisons of estimated indicator values against known impairment. We modeled how densities changed with increasing stress as a function of tolerance values. We applied this procedure to data from five reference sites and compared non-metric multidimensional scaling (NMDS) and observed taxa richness for detecting known impairments. NMDS showed that the trajectories of impairment caused by stress were all evident at 100, 300, or 600 counts. However, the discrimination of stress levels within ordination space greatly improved with increasing count. Estimates of richness based on 100- or 300-count samples often severely underestimated true taxa loss and frequently indicated taxa gain. Estimates of taxa loss based on 600 counts also underestimated true taxa loss, but these estimates were strongly correlated with true taxa loss. This simulation procedure should be applicable to the evaluation of how well a variety of biotic indicators measure biological impairment.

Cao, Y.; Hawkins, C. P.

2005-05-01

37

Fundamentals of Model Scaling in Forest Ecology  

Microsoft Academic Search

\\u000a Coping with disturbances of forest systems which result from increasing fluctuations of physical and human environments requires\\u000a a better quantitative understanding of forest ecological processes at different scales. Examples of applied scaling in forest\\u000a ecology are initially discussed to stress the practical relevance of scaling studies. Model-based reasoning serves as a starting\\u000a point of any scaling activity. Initial cognitive processes

Matthias Langensiepen

38

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 A forest ecosystem model (CASTANEA) simulating the carbon balance (canopy photosynthesis, autotrophic and heterotrophic respirations, net ecosystem exchange, wood and root growth) and the water cycle (transpiration

Boyer, Edmond

39

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

E-print Network

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

Arhonditsis, George B.

2005-01-01

40

Predictive habitat distribution models in ecology  

Microsoft Academic Search

With the rise of new powerful statistical techniques and GIS tools, the development of predictive habitat distribution models has rapidly increased in ecology. Such models are static and probabilistic in nature, since they statistically relate the geographical distribution of species or communities to their present environment. A wide array of models has been developed to cover aspects as diverse as

Antoine Guisan; Niklaus E. Zimmermann

2000-01-01

41

I. Introduction Simulation Modeling  

E-print Network

program, and modeling, experimentation, simulation, and programming methodologies or techniques used, experimentation technique, simulation methodology, and software engineering. Key Words and Phrases: assessment task the abilities of the traditional model- based methodologies. As reported by Roth, Gass

Tesfatsion, Leigh

42

Simulating Ecological Complexity Using the Example of Pesticides in Ecosystems.  

ERIC Educational Resources Information Center

Describes a simulation exercise developed for an introductory biology course for nonmajors. The simulation focuses on the control of western spruce budworms in forests of the western United States. A nonlinear, multivariate simulation model is used. (PR)

Muir, Patricia S.; McCune, Bruce

1993-01-01

43

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

USGS Publications Warehouse

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

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

2014-01-01

44

Model selection in ecology and evolution  

Microsoft Academic Search

Recently, researchers in several areas of ecology and evolution have begun to change the way in which they analyze data and make biological inferences. Rather than the traditional null hypothesis testing approach, they have adopted an approach called model selection, in which several competing hypotheses are simultaneously confronted with data. Model selection can be used to identify a single best

Jerald B. Johnson; Kristian S. Omland

2004-01-01

45

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...

46

Ecological Modelling 175 (2004) 6576 Modeling seed dispersal in a variable environment: a case study  

E-print Network

and unfavorable rain phases. Our simulation experiments show that when fruit removal rate is extremely lowEcological Modelling 175 (2004) 65­76 Modeling seed dispersal in a variable environment: a case in dispersal distance and fruit removal rate, particularly given the natural variability of the environment

Moloney, Kirk A.

47

Social Ecological Model of Multilevel Influences on Diet  

Cancer.gov

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

48

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

49

An overview of the utility of population simulation software in molecular ecology.  

PubMed

Stochastic simulation software that simultaneously model genetic, population and environmental processes can inform many topics in molecular ecology. These include forecasting species and community response to environmental change, inferring dispersal ecology, revealing cryptic mating, quantifying past population dynamics, assessing in situ management options and monitoring neutral and adaptive biodiversity change. Advances in population demographic-genetic simulation software, especially with respect to individual life history, landscapes and genetic processes, are transforming and expanding the ways that molecular data can be used. The aim of this review is to explain the roles that such software can play in molecular ecology studies (whether as a principal component or a supporting function) so that researchers can decide whether, when and precisely how simulations can be incorporated into their work. First, I use seven case studies to demonstrate how simulations are employed, their specific advantage/necessity and what alternative or complementary (nonsimulation) approaches are available. I also explain how simulations can be integrated with existing spatial, environmental, historical and genetic data sets. I next describe simulation features that may be of interest to molecular ecologists, such as spatial and behavioural considerations and species' interactions, to provide guidance on how particular simulation capabilities can serve particular needs. Lastly, I discuss the prospect of simulation software in emerging challenges (climate change, biodiversity monitoring, population exploitation) and opportunities (genomics, ancient DNA), in order to emphasize that the scope of simulation-based work is expanding. I also suggest practical considerations, priorities and elements of best practice. This should accelerate the uptake of simulation approaches and firmly embed them as a versatile tool in the molecular ecologist's toolbox. PMID:24689878

Hoban, Sean

2014-05-01

50

Modeling and simulation  

SciTech Connect

This book presents the papers given at a conference on computerized simulation. Topics considered at the conference included expert systems, modeling in electric power systems, power systems operating strategies, energy analysis, a linear programming approach to optimum load shedding in transmission systems, econometrics, simulation in natural gas engineering, solar energy studies, artificial intelligence, vision systems, hydrology, multiprocessors, and flow models.

Hanham, R.; Vogt, W.G.; Mickle, M.H.

1986-01-01

51

Ecological Modelling 106 (1998) 177200 FORMOSAIC: an individual-based spatially explicit model for  

E-print Network

Science B.V. All rights reserved. PII S0304-3800(97)00191-9 #12;J. Liu, P.S. Ashton / Ecological Modelling for simulating forest dynamics in landscape mosaics Jianguo Liu a, *, Peter S. Ashton b a Department of Fisheries and Ashton, 1992). Deforestation and timber harvesting have likely caused many species to be extirpated from

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

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

PubMed

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

2013-09-01

54

Short communication A simple stochastic weather generator for ecological modeling  

E-print Network

properties identical to the historical data. Weather is an important driver of many ecological models of real weather patterns (step 3) depends upon the context of an ecological study. Although statisticalShort communication A simple stochastic weather generator for ecological modeling A.G. Birt a,*, M

Xi, Weimin

55

Modelling the ecological niche from functional traits  

PubMed Central

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

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

2010-01-01

56

Implicit assimilation for marine ecological models  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

57

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

Joseph S. Krajcik

2009-10-14

58

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

59

USING ARTIFICIAL NEURAL NETWORK MODELS TO INTEGRATE HYDROLOGIC AND ECOLOGICAL STUDIES OF THE SNAIL KITE IN THE EVERGLADES, USA  

Microsoft Academic Search

Hydrologists and ecologists have been working in the Everglades on integrating a long- term hydrologic data network and a short-term ecological database to support ecological models of the habitat of the snail kite, a threatened and endangered bird. Data mining techniques, including artificial neural network (ANN) models, were applied to simulate the hydrology of snail kite habitat in the Water

PAUL A. CONRADS; EDWIN ROEHL; RUBY DAAMEN; WILEY M. KITCHENS

60

Model simulates ocean conditions  

NASA Astrophysics Data System (ADS)

Researchers from the National Oceanic and Atmospheric Administration (NOAA) have developed a high-resolution general circulation computer model that has been used to simulate ocean conditions in the tropical Pacific. According to George Philander of NOAA's Geophysical Fluid Dynamics Laboratory in Princeton, N.J., the new model has been used in a “remarkably realistic” simulation of the 1982-1983 El Niño event, one of the most severe on record.The model accurately recreated sea surface temperatures at different stages of the El Niño event and provided simulated currents and subsurface temperatures in excellent agreement with those actually observed, Philander said. “The model is being run in real time, and for the first time provides us with a coherent picture of oceanic conditions in the Pacific.” Later this year, the new model will be transferred to NOAA's National Meteorological Center for operational use.

61

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...

62

Spatial and space–time correlations in ecological models  

Microsoft Academic Search

Space–time autoregressive moving average (STARMA) processes can be used to represent a wide range of theoretical models of ecological variation and statistical models for analyzing ecological data. Many discrete-time, discrete-space ecological processes can be analyzed using STARMA theorems. As an example, one focus is on population genetic models, and using STARMA we obtain not only the usual spatial variance and

Bryan K. Epperson

2000-01-01

63

Cellular automata as a paradigm for ecological modeling  

Microsoft Academic Search

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

P. Hogeweg

1988-01-01

64

RHESSys: Regional Hydro-Ecologic Simulation System—An Object-Oriented Approach to Spatially Distributed Modeling of Carbon, Water, and Nutrient Cycling  

Microsoft Academic Search

Process-based models that can represent multiple and interacting processes provide a framework for combining field-based measure- ments with evolving science-based models of specific hydroecological processes. Use of these models, however, requires that the representation of processes and key assumptions involved be understood by the user community. This paper provides a full description of process implementation in the most recent version

C. L. Tague; L. E. Band

2004-01-01

65

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

PubMed Central

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

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

2013-01-01

66

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.

67

The role of ecological models in linking ecological risk assessment to ecosystem services in agroecosystems.  

PubMed

Agricultural practices are essential for sustaining the human population, but at the same time they can directly disrupt ecosystem functioning. Ecological risk assessment (ERA) aims to estimate possible adverse effects of human activities on ecosystems and their parts. Current ERA practices, however, incorporate very little ecology and base the risk estimates on the results of standard tests with several standard species. The main obstacles for a more ecologically relevant ERA are the lack of clear protection goals and the inherent complexity of ecosystems that is hard to approach empirically. In this paper, we argue that the ecosystem services framework offers an opportunity to define clear and ecologically relevant protection goals. At the same time, ecological models provide the tools to address ecological complexity to the degree needed to link measurement endpoints and ecosystem services, and to quantify service provision and possible adverse effects from human activities. We focus on the ecosystem services relevant for agroecosystem functioning, including pollination, biocontrol and eutrophication effects and present modeling studies relevant for quantification of each of the services. The challenges of the ecosystem services approach are discussed as well as the limitations of ecological models in the context of ERA. A broad, multi-stakeholder dialog is necessary to aid the definition of protection goals in terms of services delivered by ecosystems and their parts. The need to capture spatio-temporal dynamics and possible interactions among service providers pose challenges for ecological models as a basis for decision making. However, we argue that both fields are advancing quickly and can prove very valuable in achieving more ecologically relevant ERA. PMID:21802704

Galic, Nika; Schmolke, Amelie; Forbes, Valery; Baveco, Hans; van den Brink, Paul J

2012-01-15

68

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.

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

On the Integrability and Chaotic behaviour of an ecological model  

E-print Network

A three species food chain model is studied analytically as well as numerically. Integrability of the model is studied using Painleve analysis while chaotic behaviour is studied using numerical techniques, such as calculation of Lyapunov exponents, plotting the bifurcation diagram and phase plots. We correct and critically comment on the wrong results reported recently on this ecological model, in a paper by Rai ([1995] ``Modelling ecological systems'', Int. J. Bifurcation and Chaos 5, 537-543).

M. P. Joy

1996-12-02

71

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

72

Ecological behaviour of three serogroups of Legionella pneumophila within a model plumbing system  

Microsoft Academic Search

Three Legionella pneumophila strains isolated from water samples and belonging to serogroups (sgs) 1, 6 and 9 were analysed for their capacity to colonise an experimental model simulating a domestic hot water distribution system. Ecological factors that could influence the persistence of the sgs such as intracellular life within protozoan hosts and bacterial interference by the production of antagonistic compounds

P. Messi; I. Anacarso; A. Bargellini; M. Bondi; I. Marchesi; S. de Niederhäusern; P. Borella

2011-01-01

73

A Complementary Ecological Model of the Coordinated School Health Program  

ERIC Educational Resources Information Center

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

Lohrmann, David K.

2010-01-01

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

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

76

Pattern-Oriented Modeling of Agent-Based Complex Systems: Lessons from Ecology  

Microsoft Academic Search

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

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

2005-01-01

77

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...

78

Ecologic niche modeling and potential reservoirs for Chagas disease, Mexico  

E-print Network

Ecologic niche modeling may improve our understanding of epidemiologically relevant vector and parasitereservoir distributions. We used this tool to identify host relationships of Triatoma species implicated in transmission of Chagas disease...

Peterson, A. Townsend; Sá nchez-Cordero, Ví ctor; Beard, C. Ben; Ramsey, J. M.

2002-07-01

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

A simulated infrared model board  

NASA Astrophysics Data System (ADS)

Martin Marietta Aerospace has built a model board that simulates infrared imagery for aircraft windscreen and sensor displays in its Simulation and Test Laboratory. The simulation uses an image isocon TV camera with a Farrand optical probe; the video output is 525 or 875-line monochrome forward-looking IR (FLIR) imagery. This paper outlines the design objectives, discusses the appearance of the simulated FLIR imagery on the displays, and describes the techniques used in constructing and painting the model board.

Jones, C. E.; Lee, J.

81

Modeling Dynamics of Patchy Landscapes: Linking Metapopulation Theory, Landscape Ecology and Conservation Biology  

E-print Network

-world problems concerning the sustainability of ecological systems and the human society. On the other handModeling Dynamics of Patchy Landscapes: Linking Metapopulation Theory, Landscape Ecology and Conservation Biology Jianguo Wu* Department of Ecology & Evolutionary Biology Princeton University Princeton

Wu, Jianguo "Jingle"

82

The Ecological Validity of Jury Simulations: Is the Jury Still Out?  

Microsoft Academic Search

Despite the need to assess the ecological validity of jury simulation research before generalizing from simulations to the behavior of real jurors, surprisingly little jury research has directly addressed issues of validity. The present paper reviews the extant research on two aspects of the validity question—specifically, research that has compared different samples of mock jurors, and research that has manipulated

Brian H. Bornstein

1999-01-01

83

Boechera, a model system for ecological genomics  

PubMed Central

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

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

2011-01-01

84

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

85

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

86

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...

87

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...

88

State of the art of ecological modelling in limnology  

Microsoft Academic Search

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

Sven Erik Jørgensen

1995-01-01

89

Dense and sparse aggregations in complex motion: Video coupled with simulation modeling  

Technology Transfer Automated Retrieval System (TEKTRAN)

In censuses of aggregations composed of highly mobile animals, the link between image processing technology and simulation modeling remains relatively unexplored despite demonstrated ecological needs for abundance and density assessments. We introduce a framework that connects video censusing with ...

90

Guide for developing conceptual models for ecological risk assessments  

SciTech Connect

Ecological conceptual models are the result of the problem formulation phase of an ecological risk assessment, which is an important component of the Remedial Investigation process. They present hypotheses of how the site contaminants might affect the site ecology. The contaminant sources, routes, media, routes, and endpoint receptors are presented in the form of a flow chart. This guide is for preparing the conceptual models; use of this guide will standardize the models so that they will be of high quality, useful to the assessment process, and sufficiently consistent so that connections between sources of exposure and receptors can be extended across operable units (OU). Generic conceptual models are presented for source, aquatic integrator, groundwater integrator, and terrestrial OUs.

Suter, G.W., II

1996-05-01

91

Functional modelling for logic simulation  

Microsoft Academic Search

As digital integrated circuits become more complex, Computer Aided Design (CAD) must support more hierarchical design methods. Top-down design is supported in logic simulators by the inclusion of functional models. The SAndia LOGic Simulator (SALOGS) has functional modelling capability but until now only as FORTRAN subroutines. The new Structural Interface to the SALOGS Language (SISL) allows the design engineer access

Peter G. Raeth; John M. Acken; Gary B. Lamont; John M. Borky

1981-01-01

92

Dense and sparse aggregations in complex motion: Video coupled with simulation modeling  

Microsoft Academic Search

Investigations into the complex behaviors of aggregations of highly mobile animals have not used the link between image processing technology and simulation modeling fruitfully to address many fundamental ecological issues. Examples include population censusing, which remains difficult despite the demonstrated ecological importance of assessing abundance and density of organisms. We introduce a theoretical framework that connects thermal infrared video imaging

Thomas G. Hallam; Aruna Raghavan; Haritha Kolli; Dobromir T. Dimitrov; Paula Federico; Hairong Qi; Gary F. McCracken; Margrit Betke; John K. Westbrook; Kimberly Kennard; Thomas H. Kunz

2009-01-01

93

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

94

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 and predict the impact of human activities on wildlife species. This is the case for Banff and Kootenay at ScienceDirect Ecological Modelling journal homepage: www.elsevier.com/locate/ecolmodel How humans shape

Hebblewhite, Mark

2010-01-01

95

Aggregate dynamic economic - ecological models for sustainable development  

Microsoft Academic Search

The aim of the paper is to formulate a general integrated aggregate dynamic model for sustainable development, that will be both simple in structure and able to deal with the main objectives, processes, and constraints applying to sustainable development in closed economic - ecological systems. General characteristics of models to be used for sustainable development are discussed. It turns out

J C J M van den Bergh; P Nijkamp

1991-01-01

96

PLACE PRIORITIZATION FOR BIODIVERSITY REPRESENTATION USING SPECIES' ECOLOGICAL NICHE MODELING  

Microsoft Academic Search

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

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

2005-01-01

97

Numerical wind speed simulation model  

SciTech Connect

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

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

1981-09-01

98

Simulation Models in Higher Education.  

ERIC Educational Resources Information Center

This paper, adapted from a Society for College and University Planning conference, discusses cost simulation models in higher education. Emphasis is placed on the art of management, mini-models vs. maxi-models, the useful model, the reporting problem, anatomy of failure, information vs. action, and words of caution. (MJM)

Morrisseau, James J.

1973-01-01

99

Ecological Niche Modelling of Bank Voles in Western Europe  

PubMed Central

The bank vole (Myodes glareolus) is the natural host of Puumala virus (PUUV) in vast areas of Europe. PUUV is one of the hantaviruses which are transmitted to humans by infected rodents. PUUV causes a general mild form of hemorrhagic fever with renal syndrome (HFRS) called nephropathia epidemica (NE). Vector-borne and zoonotic diseases generally display clear spatial patterns due to different space-dependent factors. Land cover influences disease transmission by controlling both the spatial distribution of vectors or hosts, as well as by facilitating the human contact with them. In this study the use of ecological niche modelling (ENM) for predicting the geographical distribution of bank vole population on the basis of spatial climate information is tested. The Genetic Algorithm for Rule-set Prediction (GARP) is used to model the ecological niche of bank voles in Western Europe. The meteorological data, land cover types and geo-referenced points representing the locations of the bank voles (latitude/longitude) in the study area are used as the primary model input value. The predictive accuracy of the bank vole ecologic niche model was significant (training accuracy of 86%). The output of the GARP models based on the 50% subsets of points used for testing the model showed an accuracy of 75%. Compared with random models, the probability of such high predictivity was low (?2 tests, p < 10?6). As such, the GARP models were predictive and the used ecologic niche model indeed indicates the ecologic requirements of bank voles. This approach successfully identified the areas of infection risk across the study area. The result suggests that the niche modelling approach can be implemented in a next step towards the development of new tools for monitoring the bank vole’s population. PMID:23358234

Amirpour Haredasht, Sara; Barrios, Miguel; Farifteh, Jamshid; Maes, Piet; Clement, Jan; Verstraeten, Willem W.; Tersago, Katrien; Van Ranst, Marc; Coppin, Pol; Berckmans, Daniel; Aerts, Jean-Marie

2013-01-01

100

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

101

Assessing the Effectiveness of a Computer Simulation for Teaching Ecological Experimental Design  

ERIC Educational Resources Information Center

Designing manipulative ecological experiments is a complex and time-consuming process that is problematic to teach in traditional undergraduate classes. This study investigates the effectiveness of using a computer simulation--the Virtual Rocky Shore (VRS)--to facilitate rapid, student-centred learning of experimental design. We gave a series of…

Stafford, Richard; Goodenough, Anne E.; Davies, Mark S.

2010-01-01

102

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...

103

Simulation modeling of estuarine ecosystems  

NASA Technical Reports Server (NTRS)

A simulation model has been developed of Galveston Bay, Texas ecosystem. Secondary productivity measured by harvestable species (such as shrimp and fish) is evaluated in terms of man-related and controllable factors, such as quantity and quality of inlet fresh-water and pollutants. This simulation model used information from an existing physical parameters model as well as pertinent biological measurements obtained by conventional sampling techniques. Predicted results from the model compared favorably with those from comparable investigations. In addition, this paper will discuss remotely sensed and conventional measurements in the framework of prospective models that may be used to study estuarine processes and ecosystem productivity.

Johnson, R. W.

1980-01-01

104

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

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

Metamorphic Modelling: Simulating Metamorphic Processes  

NSDL National Science Digital Library

These activities are aimed at simulating metamorphic rock formation, and explain how increased pressure and heat affect such formation. The first activity, which can also be performed as a teacher demonstration, simulates the idea of contact metamorphism by investigating the effect of heat from a beaker of hot water on egg white. The other two laboratory activities simulate the formation of slate and simulate the distortion of fossils under pressure using plaster of Paris models. The lesson also discusses differences between igneous and metamorphic rocks.

107

Landscape Models and Explanation in Landscape Ecology--A Space for Generative Landscape Science?  

E-print Network

Landscape Models and Explanation in Landscape Ecology-- A Space for Generative Landscape Science in landscape ecology. We discuss the dual modeling goals of prediction and explanation and identify challenges landscape science is offered as a complementaryapproachtoexplanation, combiningmodelsofcandidateprocesses

Brown, Daniel G.

108

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...

109

The Quality of Home Environment in Brazil: An Ecological Model  

Microsoft Academic Search

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

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

2006-01-01

110

A Novel Integrated Ecological Model for the study of Sustainability  

EPA Science Inventory

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

111

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...

112

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...

113

book August 29, 2007 Ecological Models and Data in R  

E-print Network

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

114

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

E-print Network

. 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 a Department of Geomatics Engineering, University of Calgary, 2500 University Drive, Calgary, Alberta T2N 1N4

Hebblewhite, Mark

115

A Model of Practice in Special Education: Dynamic Ecological Analysis  

ERIC Educational Resources Information Center

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

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

2010-01-01

116

Development of stable isotope mixing models in ecology - Sydney  

EPA Science Inventory

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

117

Historical development of stable isotope mixing models in ecology  

EPA Science Inventory

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

118

Development of stable isotope mixing models in ecology - Fremantle  

EPA Science Inventory

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

119

Development of stable isotope mixing models in ecology - Dublin  

EPA Science Inventory

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

120

Development of stable isotope mixing models in ecology - Perth  

EPA Science Inventory

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

121

INTEGRATION OF AN ECONOMIC WITH AN ECOLOGICAL MODEL  

EPA Science Inventory

We summarize our work on integration of an economy under imperfect competition with a simple Lotka-Volterra type ecological model. Firms and households operate within a single period planning horizon, thus there is no savings or investment. Wages are set by a dominant employer. P...

122

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

123

Modeling Marine Phage Ecology Joseph M. Mahaffy  

E-print Network

· Modeling Species Diversity · Summarize Results · Two Compartment Model · Dynamic Model for Phage for rheumatic fever and toxic shock syndrome UBC Jan 2006 ­ p. 4/3 #12;Biological Experiment · Start with a 200

Mahaffy, Joseph M.

124

Modeling and Simulation at NASA  

NASA Technical Reports Server (NTRS)

This slide presentation is composed of two topics. The first reviews the use of modeling and simulation (M&S) particularly as it relates to the Constellation program and discrete event simulation (DES). DES is defined as a process and system analysis, through time-based and resource constrained probabilistic simulation models, that provide insight into operation system performance. The DES shows that the cycles for a launch from manufacturing and assembly to launch and recovery is about 45 days and that approximately 4 launches per year are practicable. The second topic reviews a NASA Standard for Modeling and Simulation. The Columbia Accident Investigation Board made some recommendations related to models and simulations. Some of the ideas inherent in the new standard are the documentation of M&S activities, an assessment of the credibility, and reporting to decision makers, which should include the analysis of the results, a statement as to the uncertainty in the results,and the credibility of the results. There is also discussion about verification and validation (V&V) of models. There is also discussion about the different types of models and simulation.

Steele, Martin J.

2009-01-01

125

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

126

Modelling dendritic ecological networks in space: an integrated network perspective.  

PubMed

Dendritic ecological networks (DENs) are a unique form of ecological networks that exhibit a dendritic network topology (e.g. stream and cave networks or plant architecture). DENs have a dual spatial representation; as points within the network and as points in geographical space. Consequently, some analytical methods used to quantify relationships in other types of ecological networks, or in 2-D space, may be inadequate for studying the influence of structure and connectivity on ecological processes within DENs. We propose a conceptual taxonomy of network analysis methods that account for DEN characteristics to varying degrees and provide a synthesis of the different approaches within 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). PMID:23458322

Peterson, Erin E; Ver Hoef, Jay M; Isaak, Dan J; Falke, Jeffrey A; Fortin, Marie-Josée; Jordan, 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

2013-05-01

127

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

E-print Network

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

Turner, Monica G.

128

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

129

Putting the "ecology" into environmental flows: ecological dynamics and demographic modelling.  

PubMed

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. PMID:22543580

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

2012-07-01

130

Sensitivity analysis and simulation for DOC concentration and flux in the stream in the regional hydro-ecological simulation system (RHESSys)  

NASA Astrophysics Data System (ADS)

While the individual components of carbon cycle have been well studied for a long time, the characteristics, source and destination of carbon fluxes from the land to water are still not yet clear, especially for Dissolved Organic Carbon (DOC). Empirical models have been widely used to estimate DOC in stream channels. Physical process based models are starting to play an important role in improving our knowledge as more of the key processes of DOC production and transportation are being unveiled. The Regional Hydro-Ecological Simulation System (RHESSys) is a physical process based terrestrial model that has the ability to simulate both the source and transportation of DOC by combining both hydrological and ecological processes. This current effort is focused on using the RHESSys model in a coastal urbanized watershed in New England Area. The first part of this research is a description of sensitivity tests undertaken to determine the influence of different parameters on the DOC concentration and flux from the land into the stream in RHESSys. Five groups of parameters were tested. The average and coefficient variance of DOC concentration and flux, as well as a Feedback Index (FI) (which was calculated as the change of DOC concentration and flux divided by the change of each parameter) were used to estimate the extent of these parameters' effects. Four groups of parameters were tested, including model parameters such as DOM_decay_rate, DOC_production_rate and DOC_absorption_rate, climate indices (which included temperature and N_deposition rate), soil and vegetation parameters (which included soil texture and vegetation types) and litter composition. The second part of this research focuses on simulating the DOC concentration and flux from the land to the water using RHESSys in the urbanized Neponset River watershed, which lies to the south of the city of Boston. Both efforts used 30 meters resolution input data at a daily time step. The simulated results compare favorably with field measures of DOC for the watershed.

Yang, Y.; Schaaf, C.; Tague, C.; Tenenbaum, D. E.; Wang, Z.; Douglas, E. M.; Chen, R. F.; Cialino, K. T.; Hwang, T.

2013-12-01

131

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

PubMed Central

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

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

2014-01-01

132

Research on agricultural ecology and environment analysis and modeling based on RS and GIS  

NASA Astrophysics Data System (ADS)

Analysis of agricultural ecology and environment is based on the data of agricultural resources, which are obtained by RS monitoring. The over-exploitation of farmlands will cause structural changes of the soil composition, and damage the planting environment and the agro-ecosystem. Through the research on the dynamic monitoring methods of multitemporal RS images and GIS technology, the crop growth status, crop acreage and other relevant information in agricultural production are extracted based on the monitor and analysis of the conditions of the fields and crop growth. The agro-ecological GIS platform is developed with the establishment of the agricultural resources management database, which manages spatial data, RS data and attribute data of agricultural resources. Using the RS, GIS analysis results, the reasons of agro-ecological destruction are analyzed and the evaluation methods are established. This paper puts forward the concept of utilization capacity of farmland, which describes farmland space for development and utilization that is influenced by the conditions of the land, water resources, climate, pesticides and chemical fertilizers and many other agricultural production factors. Assessment model of agricultural land use capacity is constructed with the help of Fuzzy. Assessing the utilization capacity of farmland can be helpful to agricultural production and ecological protection of farmland. This paper describes the application of the capacity evaluation model with simulated data in two aspects, namely, in evaluating the status of farmland development and utilization and in optimal planting.

Zhang, Wensheng; Chen, Hongfu; Wang, Mingsheng

2009-07-01

133

Modeling, Simulation, and Visualization  

E-print Network

based logistics. LBC Objectives: To develop a model that uses situational awareness (SA) data the occurrence of events to situational awareness by logging the events in the Situational Awareness data base. · Add complex situational analysis and decision making. LBC Layered Architecture Distribution Network

Kemner, Ken

134

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

NASA Astrophysics Data System (ADS)

Drought 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

135

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...

136

Model Predictive Control for Automobile Ecological Driving Using Traffic Signal Information  

NASA Astrophysics Data System (ADS)

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

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

137

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

E-print Network

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

Rajakaruna, Nishanta

138

Tree Modeling and Dynamics Simulation  

NASA Astrophysics Data System (ADS)

This paper introduces the theory about tree modeling and dynamic movements simulation in computer graphics. By comparing many methods we choose Geometry-based rendering as our method. The tree is decomposed into branches and leaves, under the rotation and quaternion methods we realize the tree animation and avoid the Gimbals Lock in Euler rotation. We take Orge 3D as render engine, which has good graphics programming ability. By the end we realize the tree modeling and dynamic movements simulation, achieve realistic visual quality with little computation cost.

Tian-shuang, Fu; Yi-bing, Li; Dong-xu, Shen

139

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

EPA Science Inventory

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

140

CONCEPTUAL MODEL FOR ASSESSING ECOLOGICAL RISK TO WATER QUALITY FUNCTION OF BOTTOMLAND HARDWOOD FORESTS  

EPA Science Inventory

Ecological risk assessment provides a methodology for evaluating the threats of 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 ...

141

Fiber 3.0: An ecological growth model for northeastern forest types. Forest Service general technical report (Final)  

SciTech Connect

Fiber, a stand projection growth model, simulates the growth and structural development of stands in the Northeast. The internal structure of the model is specified and constructed by the ecological type classifications of sugar maple--ash, beech--red maple, oad--white pine, spruce--fir, hemlock--spruce, and cedar--black spruce. Guidelines are provided on operational procedures for the major commercial species growing on these different ecologic land classifications for a range of even-aged and uneven-aged silvicultural treatments and harvesting schedules.

Solomon, D.S.; Herman, D.A.; Leak, W.B.

1995-05-22

142

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. PMID:25567890

Wang, Hui-Yu; Höök, Tomas O

2009-01-01

143

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

144

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

145

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

146

Predicting species invasions using ecological niche modeling  

E-print Network

that has not yet hap pel\\l'd, hut might. Cattle egrets. Cattle egrets (Bubulcus ibis) were originally r('~trictcd to the Old World Tropics in Africa and southern Asia. A flock of this species, however, was blown across the Atlantic ()ce,1...Science 367 Copyright © 2001 All Rights Reserved • x • x .~ x • x x x ~. - ...... .. Figure 1. Map of North America, illustrating predictive modeling of catt~e egret (Bubulcus ibis) invasion. Circles represent training data (occurrence pomts from...

Peterson, A. Townsend; Vieglais, David A.

2001-05-01

147

An overview of APSIM, a model designed for farming systems simulation  

Microsoft Academic Search

The Agricultural Production Systems Simulator (APSIM) is a modular modelling framework that has been developed by the Agricultural Production Systems Research Unit in Australia. APSIM was developed to simulate biophysical process in farming systems, in particular where there is interest in the economic and ecological outcomes of management practice in the face of climatic risk. The paper outlines APSIM's structure

B. A. Keating; P. S. Carberry; G. L. Hammer; M. E. Probert; M. J. Robertson; D. Holzworth; N. I. Huth; J. N. G. Hargreaves; H. Meinke; Z. Hochman; G. McLean; K. Verburg; V. Snow; J. P. Dimes; M. Silburn; E. Wang; S. Brown; K. L. Bristow; S. Asseng; S. Chapman; R. L. McCown; D. M. Freebairn; C. J. Smith

2003-01-01

148

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

149

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

150

Multiscale Stochastic Simulation and Modeling  

SciTech Connect

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

James Glimm; Xiaolin Li

2006-01-10

151

Assessment of Molecular Modeling & Simulation  

SciTech Connect

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

None

2002-01-03

152

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

153

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 to assess the role of forested areas in the global carbon cycle and in the continental water balance. During with a carbon allocation model and coupled with a soil model. CASTANEA describes canopy photosynthesis

Boyer, Edmond

154

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 constructed. From the model we estimate the stable age distribution which is important when the gall-midge

Krivan, Vlastimil

2000-01-01

155

Pattern-Oriented Modeling of Agent-Based Complex Systems: Lessons from Ecology  

NASA Astrophysics Data System (ADS)

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.

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

2005-11-01

156

Simulating spin models on GPU  

NASA Astrophysics Data System (ADS)

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.

Weigel, Martin

2011-09-01

157

Process model of fire ecology and succession in a mixed-conifer forest  

SciTech Connect

A forest succession simulator, SILVA, has been developed for the mixed-conifer forest (seven major species) of the Sierra Nevada, California, to simulate the effects of fire on forest dynamics. SILVA is an extensive modification of a simulator for forests of the northeastern United States. The simulation includes the time development of the growth in tree diameter, tree height, and leaf-area index. Recruitment and mortality are modeled stochastically. Modifications include fire ecology, temporal seed-crop patterns, and seedling-survival factors unique to Sierra Nevada forests. The probability of mortality from fire is determined by the height of crown scorch (a function of fire intensity, diameter at breast height, and bark thickness). The model simulates the dynamic and structural responses of communities to many factors. For 500-yr simulations from an initial clear-cut condition, the time-averaged basal-area ratios of Pinus ponderosa to Abies concolor were 5.2:1 and 1:16 for elevations of 1524 m and 1829 m, respectively. At 1524 m, the ratio of P. ponderosa to A. concolor decreased 59% when fire suppression was introduced. Fire provides P. ponderosa with a strong competitive advantage. Its growth form and growth rate are significant factors in its ability to evade fire. Rank correlations of species were compared with data for stands of ponderosa pine and white fir. Correlations were significant at 1% and 10% levels, respectively.

Kercher, J.R.; Axelrod, M.C.

1984-01-01

158

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

159

STATISTICS IN ECOLOGICAL MODELING; PRESENCE-ONLY DATA AND BOOSTED MARS  

E-print Network

STATISTICS IN ECOLOGICAL MODELING; PRESENCE-ONLY DATA AND BOOSTED MARS A DISSERTATION SUBMITTED was primarily motivated by current problems in eco- logical modeling. One such major problem is the so introduces boosted MARS, a new flexible modeling procedure. In ecological modeling of the habitat

Hastie, Trevor

160

Creating Simulated Microgravity Patient Models  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

161

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

162

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

163

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

E-print Network

Ecological Modelling 188 (2005) 358­373 A model of digestion modulation in grasshoppers William is presented that links digestion and gustatory responsiveness for insect herbivores using chemi- cal reactor models for digestion and feedbacks from nutrient titers in the hemolymph that determine internal delays

Logan, David

164

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

165

Healthcare Policy Modeling, Simulation, and Analysis: COMPARE  

E-print Network

reform are important issues for the American public, the healthcare industry, policy analystsHealthcare Policy Analysis Modeling, Simulation, and Analysis: COMPARE Challenge Decision and Information Sciences Division Modeling, Simulation, and Visualization Group Healthcare and possible healthcare

166

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

167

Process-Driven Ecological Modeling for Landscape Change Analysis  

NASA Astrophysics Data System (ADS)

Landscape pattern is an important driver in ecosystem dynamics and can control system-level functions such as nutrient cycling, connectivity, biodiversity and carbon sequestration. However, the links between process, pattern and function remain ambiguous. Understanding the quantitative relationship between ecological processes and landscape pattern across temporal and spatial scales is vital for successful management and implementation of ecosystem-level projects. We used remote sensing imagery to develop critical landscape metrics to understand the factors influencing landscape change. Our study area, a coastal area in southwest Florida, is highly dynamic with critically eroding beaches and a range of natural and developed land cover types. Hurricanes in 2004 and 2005 caused a breach along the coast of North Captiva Island that filled in by 2010. We used a time series of light detection and ranging (lidar) elevation data and hyperspectral imagery from 2006 and 2010 to determine land cover changes. Landscape level metrics used included: Largest Patch Index, Class Area, Area-weighted mean area, Clumpiness, Area-weighted Contiguity Index, Number of Patches, Percent of landcover, Area-weighted Shape. Our results showed 1) 27% increase in sand/soil class as the channel repaired itself and shoreline was reestablished, 2) 40% decrease in the mudflat class area due to conversion to sand/soil and water, 3) 30% increase in non-wetland vegetation class as a result of new vegetation around the repaired channel, and 4) the water class only slightly increased though there was a marked increase in the patch size area. Thus, the smaller channels disappeared with the infilling of the channel, leaving much larger, less complex patches behind the breach. Our analysis demonstrated that quantification of landscape pattern is critical to linking patterns to ecological processes and understanding how both affect landscape change. Our proof of concept indicated that ecological processes can correlate to landscape pattern and that ecosystem function changes significantly as pattern changes. However, the number of links between landscape metrics and ecological processes are highly variable. Extensively studied processes such as biodiversity can be linked to numerous landscape metrics. In contrast, correlations between sediment cycling and landscape pattern have only been evaluated for a limited number of metrics. We are incorporating these data into a relational database linking landscape and ecological patterns, processes and metrics. The database will be used to parameterize site-specific landscape evolution models projecting how landscape pattern will change as a result of future ecosystem restoration projects. The model is a spatially-explicit, grid-based model that projects changes in community composition based on changes in soil elevations. To capture scalar differences in landscape change, local and regional landscape metrics are analyzed at each time step and correlated with ecological processes to determine how ecosystem function changes with scale over time.

Altman, S.; Reif, M. K.; Swannack, T. M.

2013-12-01

168

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

PubMed

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

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

2015-01-01

169

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

PubMed Central

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

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

2015-01-01

170

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

171

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

172

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

173

Modelling and simulation of radiotherapy  

NASA Astrophysics Data System (ADS)

In this paper, models are described which have been developed to model both the way in which a population of cells respond to radiation and the way in which a population of patients respond to radiotherapy to assist the conduct of clinical trials in silico. Population balance techniques have been used to simulate the age distribution of tumour cells in the cell cycle. Sensitivity to radiation is not constant round the cell cycle and a single fraction of radiation changes the age distribution. Careful timing of further fractions of radiation can be used to maximize the damage delivered to the tumour while minimizing damage to normal tissue. However, tumour modelling does not necessarily predict patient outcome. A separate model has been established to predict the course of a brain cancer called glioblastoma multiforme (GBM). The model considers the growth of the tumour and its effect on the normal brain. A simple representation is included of the health status of the patient and hence the type of treatment offered. It is concluded that although these and similar models have a long way yet to be developed, they are beginning to have an impact on the development of clinical practice.

Kirkby, Norman F.

2007-02-01

174

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

175

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

176

Ubiquitin: molecular modeling and simulations.  

PubMed

The synthesis and destruction of proteins are imperative for maintaining their cellular homeostasis. In the 1970s, Aaron Ciechanover, Avram Hershko, and Irwin Rose discovered that certain proteins are tagged by ubiquitin before degradation, a discovery that awarded them the 2004 Nobel Prize in Chemistry. Compelling data gathered during the last several decades show that ubiquitin plays a vital role not only in protein degradation but also in many cellular functions including DNA repair processes, cell cycle regulation, cell growth, immune system functionality, hormone-mediated signaling in plants, vesicular trafficking pathways, regulation of histone modification and viral budding. Due to the involvement of ubiquitin in such a large number of diverse cellular processes, flaws and impairments in the ubiquitin system were found to be linked to cancer, neurodegenerative diseases, genetic disorders, and immunological disorders. Hence, deciphering the dynamics and complexity of the ubiquitin system is of significant importance. In addition to experimental techniques, computational methodologies have been gaining increasing influence in protein research and are used to uncover the structure, stability, folding, mechanism of action and interactions of proteins. Notably, molecular modeling and molecular dynamics simulations have become powerful tools that bridge the gap between structure and function while providing dynamic insights and illustrating essential mechanistic characteristics. In this study, we present an overview of molecular modeling and simulations of ubiquitin and the ubiquitin system, evaluate the status of the field, and offer our perspective on future progress in this area of research. PMID:24113788

Ganoth, Assaf; Tsfadia, Yossi; Wiener, Reuven

2013-11-01

177

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

E-print Network

Ecological Modelling 170 (2003) 453­469 Modeling the brown bear population in Slovenia A tool as populations of other large predator species, such as wolf (Canis lupus) and lynx (Lynx lynx). The Slovenian it represents the source for natural re-colonization or reintroduction of the bear into Slovenia's neighboring

Dzeroski, Saso

2003-01-01

178

Ecological Modelling 154 (2002) 7591 Modeling landscape net ecosystem productivity (LandNEP)  

E-print Network

Ecological Modelling 154 (2002) 75­91 Modeling landscape net ecosystem productivity (LandNEP) under distribution of net ecosystem productivity (NEP) in a mosaic are dependent on ecosystem type and the chronose ecosystem productivity (NEP); Carbon flux; Landscape; Disturbance; Management www

Chen, Jiquan

179

Strategies for fitting nonlinear ecological models in R, AD Model Builder, and BUGS  

USGS Publications Warehouse

1. Ecologists often use nonlinear fitting techniques to estimate the parameters of complex ecological models, with attendant frustration. This paper compares three open-source model fitting tools and discusses general strategies for defining and fitting models. 2. R is convenient and (relatively) easy to learn, AD Model Builder is fast and robust but comes with a steep learning curve, while BUGS provides the greatest flexibility at the price of speed. 3. Our model-fitting suggestions range from general cultural advice (where possible, use the tools and models that are most common in your subfield) to specific suggestions about how to change the mathematical description of models to make them more amenable to parameter estimation. 4. A companion web site (https://groups.nceas.ucsb.edu/nonlinear-modeling/projects) presents detailed examples of application of the three tools to a variety of typical ecological estimation problems; each example links both to a detailed project report and to full source code and data.

Bolker, Benjamin M.; Gardner, Beth; Maunder, Mark; Berg, Casper W.; Brooks, Mollie; Comita, Liza; Crone, Elizabeth; Cubaynes, Sarah; Davies, Trevor; de Valpine, Perry; Ford, Jessica; Gimenez, Olivier; Kéry, Marc; Kim, Eun Jung; Lennert-Cody, Cleridy; Magunsson, Arni; Martell, Steve; Nash, John; Nielson, Anders; Regentz, Jim; Skaug, Hans; Zipkin, Elise

2013-01-01

180

Application of an integrative hydro-ecological model to study water resources management in the upper and middle parts of the Yellow River basin  

NASA Astrophysics Data System (ADS)

This study presents an application of a well-calibrated integrative hydro-ecological model to examine water resources management in the upper and middle parts of the Yellow River basin, an arid and semiarid area in northwestern China. The hydro-ecological model was developed to simulate dynamic and accumulative hydrologic, ecologic, and economic variables at different spatial units. Four water management scenarios based on water use priorities, a business-as-usual scenario, an ecological scenario, an irrigation use efficiency scenario and water use scenario were designed and modeled over the period of 2011-2020 to reflect alternative water management pathways to the future. Water resource conditions were assessed in terms streamflow, actual evapotranspiration, soil water, groundwater yield, overall water yield, and derived indicator of drought index. Unit crop yield was to assess ecological production, and monetary values of crop productivity and water productivity were used to assess economic output. Scenario analysis results suggested that water stress would continue in the study region under both current water use patterns and ecological scenarios of river flow being fully satisfied.Water use scenarios would result in decreased water availability and ecosystem degradation in the long run. Improving irrigation use efficiency would be the most efficient approach in securing long-term water and food supply. The simulation results from this study provided useful information for evaluating long-term water resources management strategies, and will contribute to the knowledge of interdisciplinary modeling for water resources management in the study region.

Li, Xianglian; Gao, Qiong; Lei, Tingwu; Yang, Xiusheng

2011-03-01

181

Modeling and Simulation in Security Evaluation  

Microsoft Academic Search

Digital computers' earliest applications evaluated models of physical systems to predict their behavior under controlled conditions. To do this, they used simulation, computing changes to the models' state variables as a function of time. Since then, simulation has become fundamental to computer science. Developments in security have their roots elsewhere, but points of contact are increasing between security and simulation,

David M. Nicol

2005-01-01

182

Simulation graphical modeling and analysis (SIGMA) tutorial  

Microsoft Academic Search

SIGMA (?), an interactive graphics approach to teaching discrete event simulation, is described. ? is specifically designed to make learning the fundamentals of simulation modeling easy. ? can automatically translate a simulation model into Pascal or C source code that can be compiled and run on a wide variety of computers. It is possible to represent systems in all of

L. W. Schruben

1990-01-01

183

Integrated support environments for simulation modelling  

Microsoft Academic Search

The general concept of an integrated software support environment to enhance the productivity of the simulation modeller has motivated several groups to design and implement such environments. Underlying each such development is a perspective, implicit or explicit, of the methodology of simulation modelling. This paper rewews the experience of the Computer Aided Simulation Modellin8 (CASM)group at the London School of

David W. Balmer; Ray J. Paul

1990-01-01

184

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

Microsoft Academic Search

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

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

2009-01-01

185

Distribution of Capybaras in an Agroecosystem, Southeastern Brazil, Based on Ecological Niche Modeling  

Microsoft Academic Search

Southeastern Brazil has seen dramatic landscape modifications in recent decades, due to expansion of agriculture and urban areas; these changes have influenced the distribution and abundance of vertebrates. We developed predictive models of ecological and spatial distributions of capybaras (Hydrochoerus hydrochaeris) using ecological niche modeling. Most occurrences of capybaras were in flat areas with water bodies surrounded by sugarcane and

A. Townsend Peterson; Ricardo Scachetti-Pereira; Carlos A. Vettorazzi; Luciano M. Verdade

2009-01-01

186

Research on the sustainable development capacity based on ecological footprint model in the Northeast of China from 1999?2008  

Microsoft Academic Search

Taking the Northeast as the example, this paper put forward a model for evaluating regional sustainable development capacity which was based on ecological footprint method. The result was shown that ecological footprint per capita, ecological carrying capacity per capita and ecological deficit per capita were still rising up, it indicated that the Northeast was in unsustainable development. But GDP footprint

Wu Di; Chunyou Wu; Dawei Xu

2010-01-01

187

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

188

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

189

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

190

Social network models predict movement and connectivity in ecological landscapes  

PubMed Central

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. PMID:22084081

Fletcher, Robert J.; Acevedo, Miguel A.; Reichert, Brian E.; Pias, Kyle E.; Kitchens, Wiley M.

2011-01-01

191

A National Disturbance Modeling System to Support Ecological Carbon Sequestration Assessments  

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

192

Sensitivity analysis as an aid in modelling and control of (poorly-defined) ecological systems. [closed ecological systems  

NASA Technical Reports Server (NTRS)

A literature review of the use of sensitivity analyses in modelling nonlinear, ill-defined systems, such as ecological interactions is presented. Discussions of previous work, and a proposed scheme for generalized sensitivity analysis applicable to ill-defined systems are included. This scheme considers classes of mathematical models, problem-defining behavior, analysis procedures (especially the use of Monte-Carlo methods), sensitivity ranking of parameters, and extension to control system design.

Hornberger, G. M.; Rastetter, E. B.

1982-01-01

193

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

194

Benchmark simulation models, quo vadis?  

PubMed

As the work of the IWA Task Group on Benchmarking of Control Strategies for wastewater treatment plants (WWTPs) is coming to an end, it is essential to disseminate the knowledge gained. For this reason, all authors of the IWA Scientific and Technical Report on benchmarking have come together to provide their insights, highlighting areas where knowledge may still be deficient and where new opportunities are emerging, and to propose potential avenues for future development and application of the general benchmarking framework and its associated tools. The paper focuses on the topics of temporal and spatial extension, process modifications within the WWTP, the realism of models, control strategy extensions and the potential for new evaluation tools within the existing benchmark system. We find that there are major opportunities for application within all of these areas, either from existing work already being done within the context of the benchmarking simulation models (BSMs) or applicable work in the wider literature. Of key importance is increasing capability, usability and transparency of the BSM package while avoiding unnecessary complexity. PMID:23823534

Jeppsson, U; Alex, J; Batstone, D J; Benedetti, L; Comas, J; Copp, J B; Corominas, L; Flores-Alsina, X; Gernaey, K V; Nopens, I; Pons, M-N; Rodríguez-Roda, I; Rosen, C; Steyer, J-P; Vanrolleghem, P A; Volcke, E I P; Vrecko, D

2013-01-01

195

Ecological Modelling 132 (2000) 175190 Edge effects in fragmented landscapes: a generic model for  

E-print Network

for delineating area of edge influences (D-AEI) Daolan Zheng *, Jiquan Chen School of Forestry and Wood Products@geog.umd.edu (D. Zheng). 0304-3800/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved. PII: S0304-3800(00)00254-4 #12;D. Zheng, J. Chen / Ecological Modelling 132 (2000) 175­190176 al., 1993

Chen, Jiquan

196

Ecological Modeling with Soils Data: Semiparametric Stochastic Mixed Models  

E-print Network

buffer environmental change ­ regulating and partitioning water flow (infiltration vs. runoff ­ additive varying-coefficient model using penalized splines ­ spatial dependence through low-rank stochastic

197

Resolving Ecological Questions through Meta-Analysis: Goals, Metrics, and Models  

E-print Network

1105 S pec ial Featu r e Ecology, 80(4), 1999, pp. 1105–1117 q 1999 by the Ecological Society of America RESOLVING ECOLOGICAL QUESTIONS THROUGH META-ANALYSIS: GOALS, METRICS, AND MODELS CRAIG W. OSENBERG,1,5 ORLANDO SARNELLE,2,6 SCOTT D. COOPER,3... studies. Meta-analysis aims to rectify this shortcoming. Meta-analysis is the quantitative synthesis, analysis, and summary of a collection of studies (Hedges and Olkin 1985). Meta-analysis requires that the results of 1106 Ecology, Vol. 80, No. 4CRAIG W...

Osenberg, Craig W.; Sarnelle, Orlando; Cooper, Scott D.; Holt, Robert D.

1999-01-01

198

Fusion Simulation Project (Whole Tokamak Plasma Modeling)  

E-print Network

for a burning plasma simulation capability ­ Emergence of petascale computing capability ­ KnowledgeFusion Simulation Project (Whole Tokamak Plasma Modeling) FSP Committee and Panels Presented;PSACI June 7-8, 2007 PPPL FSP Objective and Motivation · Primary objective of Fusion Simulation

199

Deriving simulators for hybrid Chi models  

Microsoft Academic Search

The hybrid Chi language is a formalism for modeling, simulation and verification of hybrid systems. The formal semantics of hybrid Chi allows the definition of provably correct implementations for simulation, verification and real-time control. This paper discusses the principles of deriving an implementation for simulation and verification directly from the semantics, and presents an implementation based on a symbolic solver.

D. A. van Beek; K. L. Man; M. A. Reniers; J. E. Rooda; R. R. H. Schiffelers

2006-01-01

200

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

201

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...

202

A malaria transmission-directed model of mosquito life cycle and ecology  

PubMed Central

Background Malaria is a major public health issue in much of the world, and the mosquito vectors which drive transmission are key targets for interventions. Mathematical models for planning malaria eradication benefit from detailed representations of local mosquito populations, their natural dynamics and their response to campaign pressures. Methods A new model is presented for mosquito population dynamics, effects of weather, and impacts of multiple simultaneous interventions. This model is then embedded in a large-scale individual-based simulation and results for local elimination of malaria are discussed. Mosquito population behaviours, such as anthropophily and indoor feeding, are included to study their effect upon the efficacy of vector control-based elimination campaigns. Results Results for vector control tools, such as bed nets, indoor spraying, larval control and space spraying, both alone and in combination, are displayed for a single-location simulation with vector species and seasonality characteristic of central Tanzania, varying baseline transmission intensity and vector bionomics. The sensitivities to habitat type, anthropophily, indoor feeding, and baseline transmission intensity are explored. Conclusions The ability to model a spectrum of local vector species with different ecologies and behaviours allows local customization of packages of interventions and exploration of the effect of proposed new tools. PMID:21999664

2011-01-01

203

A qualitative multi-attribute model for economic and ecological assessment of genetically modified crops  

Microsoft Academic Search

Genetically modified (GM) crops have become a real option in modern agriculture. They offer advantages for agricultural production, but they also raise concerns about their ecological and economic impacts. Decisions about GM crops are complex and call for decision support. This paper presents a qualitative multi-attribute model for the assessment of ecological and economic impacts at a farm-level of GM

Marko Bohanec; Antoine Messéan; Sara Scatasta; Frédérique Angevin; Bryan Griffiths; Paul Henning Krogh; Martin Žnidarši?; Sašo Džeroski

2008-01-01

204

Multi-Attribute Modelling of Economic and Ecological Impacts of Agricultural Innovations on Cropping Systems  

E-print Network

ABSTRACT Modeling of economic and ecological impacts of genetically modified crops is a demanding task. We of genetically modified crops . One of the goals of the project is to develop a computer-based decision support system for the assessment of economic and ecological impacts of using genetically modified crops

Bohanec, Marko

205

Interdisciplinary Industrial Ecology Education: Recommendations for an Inclusive Pedagogical Model  

ERIC Educational Resources Information Center

Industrial ecology education is being developed and delivered predominantly within the domains of engineering and management. Such an approach could prove somewhat limiting to the broader goal of developing industrial ecology as an integrated knowledge base inclusive of diverse disciplines, contributing to sustainable development. This paper…

Sharma, Archana

2009-01-01

206

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

207

Pattern-oriented inverse simulation for agent-based modeling: an analysis of family strategies  

Microsoft Academic Search

Pattern Oriented Modeling (POM) is an approach to bottom-up complex system analysis, which was developed in ecology and for agent-based complex systems. This paper proposes a pattern-oriented inverse simulation (PIS) to analyze agent-based complex systems. We apply PIS to a history simulation domain, which aims to analyze a particular family line with more successful candidates in the civil service examination

Chao Yang; Setsuya Kurahashi; Isao Ono; Takao Terano

2010-01-01

208

Uncalibrated Building Energy Simulation Modeling Results  

E-print Network

of the ongoing monitoring of numerous campus buildings. Each building’s energy data were not made available until after the simulations and the analysis of the simulation results were completed. The energy use data were then compared to the simulated energy use...VOLUME 12, NUMBER 4 HVAC&R RESEARCH OCTOBER 2006 1141 Uncalibrated Building Energy Simulation Modeling Results Mushtaq Ahmad Charles H. Culp, PhD, PE Associate Member ASHRAE Fellow ASHRAE Received June 23, 2005; accepted April 17, 2006...

Ahmad, M.; Culp, C.H.

209

Stream temperature modeling and its integration with watershed hydrologic simulation  

NASA Astrophysics Data System (ADS)

Assessments of aquatic habitat and ecosystem risk depend on reliable representation of water quality variables including stream temperature. Presented in this paper is the modeling effort by integrating stream temperature prediction with hydrologic simulations at watershed scale. In specific, the Soil and Water Assessment Tool (SWAT) was adapted as a framework of watershed hydrology simulation for the integration of two modeling approaches for stream temperature, (1) a regression relationship between air-water temperature adjusted by river discharge, and (2) a hydroclimatological model considering lumped heat contribution and exchange. A watershed-scale model accounting for landscape processes and stream connectivity would provide more flexibility and extensibility to a stream temperature predictor, and facilitate the evaluation of stream temperature effects on water quality and ecosystem health. The resultant modeling system was applied to a snowmelt-dominated mountain system in the Boise River Basin, Idaho, with a high-quality stream temperature monitoring network maintained by the U.S. Forest Service. Model evaluation was conducted at both annual and seasonal time scales. Results suggested that modeling performance was associated with the temporal variations of the hydrologic and weather conditions. Seasonally varying parameters are required for more accurate predictions of stream temperature especially for a snowmelt-driven system such as the Boise River Basin. The integrated model is anticipated to support potentially novel ecological applications including habitat assessment and recovery, as well as watershed management and planning for water quality variables sensitive to stream temperature.

Luo, Y.; Ficklin, D. L.; Stewart, I. T.; Isaak, D.

2012-12-01

210

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

Microsoft Academic Search

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

Jouni Korhonen

211

Industrial ecology in the strategic sustainable development model: strategic applications of industrial ecology  

Microsoft Academic Search

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

Jouni Korhonen

2004-01-01

212

SSA Modeling and Simulation with DIRSIG  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

213

The ecological effects of thermopeaking in Alpine streams in flume simulations  

NASA Astrophysics Data System (ADS)

In Alpine areas, the temporal patterns of hydropower plants operations can have consequences for the water bodies which receive downstream releases in the form of "hydropeaking", typically consisting in sharp releases of turbinated water in the river reaches below dams. Hydropeaking may significantly affect also the thermal regime of rivers: typically power plants fed by hypolimnetic releases from large dams cause a reduction in summer temperature and an increase in winter temperatures for long distances downstream. Very few studies have addressed the effects of the short-term temperature fluctuations related to hydropeaking (i.e., thermopeaking) on aquatic fauna, although they can be a major cause of riverine habitat degradation posing serious threats to aquatic communities. In the Adige River watershed, warm thermopeaking occurs from September to January and results in additional (up to 4°C) heating to the natural dial fluctuations; cold thermopeaking occurs from March to July and cools down the temperature (up to 6°C), in contrast with the natural trend that would result in heating during the day. The biological effects of thermopeaking are difficult to study in nature, because they are associated with hydropeaking, which is known to cause a high catastrophic drift due to the increased intensity of bed scour. However, controlled simulations of thermopeaking events could be performed in artificial flumes. We used artificial flumes which had proved to perform discharge manipulations which simulate hydropeaking events, and conducted four simulations, two warm thermopeakings in early and late winter, and two cold-thermopeakings, in early and late summer, respectively. The impact of thermopeaking on benthic macroinvertebrates was assessed by collecting those organisms which are displaced from the substrate and drift in the water column. Displacement can be active (i.e., part of the behavioural repertoire of certain insect species), or passive (i.e., catastrophic and generated by any disturbance). Drifting invertebrates were collected at time intervals before the simulation, and at continuous, short-time intervals during the simulation in order to follow the changes in drift over a short time period during the simulation. We assessed the effects of thermopreaking on the benthos community by answering to the following questions: 1) Do thermal alterations induce an increase in drift of benthic invertebrates? 3) Do a reduction or an increase in water temperature have different effects of invertebrate drift? Benthic invertebrates responded more to the cold thermopeaking simulations, with differences among taxa with different life strategies and ecological requirements.

Maiolini, Bruno; Carolli, Mauro; Bruno, M. Cristina; Siviglia, Annunziato

2010-05-01

214

Modeling techniques for simulating well behavior  

E-print Network

to model the combined effect of wellbore storage and skin in pressure-transient test are developed. These relations enable this effect to be modeled in any conventional reservoir simulator without the need to modify the existing program. Alternative grid...

Rattu, Bungen Christina

2002-01-01

215

Assessing the trophic position and ecological role of squids in marine ecosystems by means of food-web models  

NASA Astrophysics Data System (ADS)

We synthesized available information from ecological models at local and regional scales to obtain a global picture of the trophic position and ecological role of squids in marine ecosystems. First, static food-web models were used to analyze basic ecological parameters and indicators of squids: biomass, production, consumption, trophic level, omnivory index, predation mortality diet, and the ecological role. In addition, we developed various dynamic temporal simulations using two food-web models that included squids in their parameterization, and we investigated potential impacts of fishing pressure and environmental conditions for squid populations and, consequently, for marine food webs. Our results showed that squids occupy a large range of trophic levels in marine food webs and show a large trophic width, reflecting the versatility in their feeding behaviors and dietary habits. Models illustrated that squids are abundant organisms in marine ecosystems, and have high growth and consumption rates, but these parameters are highly variable because squids are adapted to a large variety of environmental conditions. Results also show that squids can have a large trophic impact on other elements of the food web, and top-down control from squids to their prey can be high. In addition, some squid species are important prey of apical predators and may be keystone species in marine food webs. In fact, we found strong interrelationships between neritic squids and the populations of their prey and predators in coastal and shelf areas, while the role of squids in open ocean and upwelling ecosystems appeared more constrained to a bottom-up impact on their predators. Therefore, large removals of squids will likely have large-scale effects on marine ecosystems. In addition, simulations confirm that squids are able to benefit from a general increase in fishing pressure, mainly due to predation release, and quickly respond to changes triggered by the environment. Squids may thus be very sensitive to the effects of fishing and climate change.

Coll, Marta; Navarro, Joan; Olson, Robert J.; Christensen, Villy

2013-10-01

216

VALIDATING SIMULATION MODELS Klaus G. Troitzsch  

E-print Network

, stochastic model, simulation model, validation. ABSTRACT This paper discusses aspects of validating their generalisations around observation, developing new theo- retical structures based on and validated by new evidence of this trait of thinking is the role of simulation or computational mod- eling which can be found in Gilbert

Tesfatsion, Leigh

217

Crop Simulation Models and Decision Support Systems  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

218

System Effectiveness Simulation Model with Nonparametric Dependability  

Microsoft Academic Search

The simulation model presented here is a useful extension of WSEIAC's system's effectiveness methodology. This model accepts information regarding uncertainty with the parametric estimates of the system's attributes. One of the system's attributes, defined as “dependability,” requires Markovian State Transition Process. Time-dependent queueing process and renewal theory application for this dependability matrix are avoided by resorting to a simulation technique.

V. Balachandran

1971-01-01

219

SIMULATION MODELLING OF DEMENTIA PATIENT PATHWAYS  

E-print Network

SIMULATION MODELLING OF DEMENTIA PATIENT PATHWAYS Mohsen Jahangirian, Julie Eatock School of Information Systems, Computing and Mathematics Brunel University, London, UK MalesFemales DEMENTIA `DISEASE-diagnosed patients Disease Progression Disease Onset Community Care DEMENTIA PATHWAY SIMULATION HIGH- LEVEL MODEL

Oakley, Jeremy

220

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.

221

Modelling parasite aggregation: disentangling statistical and ecological approaches.  

PubMed

The overdispersion in macroparasite infection intensity among host populations is commonly simulated using a constant negative binomial aggregation parameter. We describe an alternative to utilising the negative binomial approach and demonstrate important disparities in intervention efficacy projections that can come about from opting for pattern-fitting models that are not process-explicit. We present model output in the context of the epidemiology and control of soil-transmitted helminths due to the significant public health burden imposed by these parasites, but our methods are applicable to other infections with demonstrable aggregation in parasite numbers among hosts. PMID:24703868

Yakob, Laith; Soares Magalhães, Ricardo J; Gray, Darren J; Milinovich, Gabriel; Wardrop, Nicola; Dunning, Rebecca; Barendregt, Jan; Bieri, Franziska; Williams, Gail M; Clements, Archie C A

2014-05-01

222

Modeling and simulation for hybrid electric vehicles. II. Simulation  

Microsoft Academic Search

For pt.I see ibid., vol.3, no.4, p.235-43 (2002). Hybrid electric vehicle (HEV) simulation is conducted based on the model developed for a parallel HEV built in the University of Tennessee, Knoxville (UT-HEV). The HEV simulation is a parametric analysis of the power control schemes and vehicle performance. Major parameters are evaluated for the vehicle driven under the standard urban and

Xiaoling He; Jeffrey W. Hodgson

2002-01-01

223

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...

224

Target modelling for SAR image simulation  

NASA Astrophysics Data System (ADS)

This paper examines target models that might be used in simulations of Synthetic Aperture Radar imagery. We examine the basis for scattering phenomena in SAR, and briefly review the Swerling target model set, before considering extensions to this set discussed in the literature. Methods for simulating and extracting parameters for the extended Swerling models are presented. It is shown that in many cases the more elaborate extended Swerling models can be represented, to a high degree of fidelity, by simpler members of the model set. Further, it is shown that it is quite unlikely that these extended models would be selected when fitting models to typical data samples.

Willis, Chris J.

2014-10-01

225

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

226

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; Nyári, Árpád S.; Perkins, Susan L.; Guralnick, Robert P.

2007-01-01

227

Modeling the ecological impacts of Flaming Gorge Dam operations  

SciTech Connect

Hydropower operations at Flaming Gorge Dam on the Green River in Utah, US, can produce rapid downstream changes in flow and stage during a day. These changes can, in turn, affect ecological resources below the dam, including riparian vegetation, trout, and endangered fish. Four hydropower operational scenarios featuring varying degrees of hydropower-induced flow fluctuation were evaluated with hydrologic models and multispectral aerial videography of the river. Year-round high fluctuations would support the least amount of stable spawning habitat for trout and nursery habitat for endangered fish, and would have the greatest potential for reducing growth and over winter survival of fish. Seasonally, adjusted moderate fluctuation and seasonally adjusted steady flow scenarios could increase food production and over winter survival and would provide the greatest amount of spawning and nursery habitat for fish. The year-round high fluctuation, seasonally adjusted high fluctuation, and seasonally adjusted moderate fluctuation scenarios would result in a 5% decrease in upper riparian zone habitat. the seasonally adjusted steady flow scenario would result in an 8% increase in upper riparian zone habitat. Lower riparian zone habitat would increase by about 17% for year-round and seasonally adjusted high fluctuating flow scenarios but decrease by about 24% and 69% for seasonally adjusted moderate fluctuating and steady flow scenarios, respectively.

Yin, S.C.L.; LaGory, K.E.; Hayse, J.W.; Hlohowskyj, I.; Van Lonkhuyzen, R.A.; Cho, H.E. [Argonne National Lab., IL (United States). Environmental Assessment Div.

1996-05-01

228

A spatially explicit hydro-ecological modeling framework (BEPS-TerrainLab V2.0): Model description and test in a boreal ecosystem in Eastern North America  

NASA Astrophysics Data System (ADS)

SummaryA spatially explicit, process-based hydro-ecological model, BEPS-TerrainLab V2.0, was developed to improve the representation of ecophysiological, hydro-ecological and biogeochemical processes of boreal ecosystems in a tightly coupled manner. Several processes unique to boreal ecosystems were implemented including the sub-surface lateral water fluxes, stratification of vegetation into distinct layers for explicit ecophysiological representation, inclusion of novel spatial upscaling strategies and biogeochemical processes. To account for preferential water fluxes common in humid boreal ecosystems, a novel scheme was introduced based on laboratory analyses. Leaf-scale ecophysiological processes were upscaled to canopy-scale by explicitly considering leaf physiological conditions as affected by light and water stress. The modified model was tested with 2 years of continuous measurements taken at the Eastern Old Black Spruce Site of the Fluxnet-Canada Research Network located in a humid boreal watershed in eastern Canada. Comparison of the simulated and measured ET, water-table depth (WTD), volumetric soil water content (VSWC) and gross primary productivity (GPP) revealed that BEPS-TerrainLab V2.0 simulates hydro-ecological processes with reasonable accuracy. The model was able to explain 83% of the ET, 92% of the GPP variability and 72% of the WTD dynamics. The model suggests that in humid ecosystems such as eastern North American boreal watersheds, topographically driven sub-surface baseflow is the main mechanism of soil water partitioning which significantly affects the local-scale hydrological conditions.

Govind, Ajit; Chen, Jing Ming; Margolis, Hank; Ju, Weimin; Sonnentag, Oliver; Giasson, Marc-André

2009-04-01

229

Ecologic niche modeling of *Blastomyces dermatitidis* in Wisconsin  

E-print Network

variables, we predicted that ecologic conditions favorable for maintaining the fungus in nature occur predominantly within northern counties and counties along the western shoreline of Lake Michigan. Areas of highest predicted occurrence were often...

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

2008-04-30

230

STABLE ISOTOPES IN ECOLOGICAL STUDIES: NEW DEVELOPMENTS IN MIXING MODELS  

EPA Science Inventory

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

231

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

232

Simulation modeling for the health care manager.  

PubMed

This article addresses the use of simulation software to solve administrative problems faced by health care managers. Spreadsheet add-ins, process simulation software, and discrete event simulation software are available at a range of costs and complexity. All use the Monte Carlo method to realistically integrate probability distributions into models of the health care environment. Problems typically addressed by health care simulation modeling are facility planning, resource allocation, staffing, patient flow and wait time, routing and transportation, supply chain management, and process improvement. PMID:19668066

Kennedy, Michael H

2009-01-01

233

Composition and analysis of a model waste for a CELSS (Controlled Ecological Life Support System)  

NASA Technical Reports Server (NTRS)

A model waste based on a modest vegetarian diet is given, including composition and elemental analysis. Its use is recommended for evaluation of candidate waste treatment processes for a Controlled Ecological Life Support System (CELSS).

Wydeven, T. J.

1983-01-01

234

ecological modelling 1 9 8 ( 2 0 0 6 ) 115126 available at www.sciencedirect.com  

E-print Network

-based models Volker Grimma, , Uta Bergerb , Finn Bastiansena , Sigrunn Eliassenc , Vincent Ginotd , Jarl Giskec St.-Paul, 84 814 Avignon Cedex 9, France e Centre for Ecology and Hydrology, Winfrith Technology

Tesfatsion, Leigh

235

Ecological niche modeling implicates climatic adaptation, competitive exclusion, and niche conservatism among Larrea  

E-print Network

Ecological niche modeling implicates climatic adaptation, competitive exclusion, and niche conservatism among Larrea tridentata cytotypes in North American deserts1,2 Robert G. Laport3 , Layla Hatem implicates climatic adaptation, competitive exclusion, and niche conservatism among Larrea tridentata

Ramsey, Justin

236

ECOLOGY AND GEOGRAPHY OF AVIAN VIRUSES USING NICHE MODELS AND WILD BIRD SURVEILLANCE  

E-print Network

The emergence of highly pathogenic avian influenza strain H5N1 (hereafter "H5N1"), and other bird-associated viruses, have raised serious concerns about impacts on human, livestock, and wildlife populations. Ecological niche modelling (ENM...

Williams, Richard A. J.

2010-12-14

237

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

238

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

239

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

240

Simulation modeling and analysis with Arena  

SciTech Connect

The textbook which treats the essentials of the Monte Carlo discrete-event simulation methodology, and does so in the context of a popular Arena simulation environment. It treats simulation modeling as an in-vitro laboratory that facilitates the understanding of complex systems and experimentation with what-if scenarios in order to estimate their performance metrics. The book contains chapters on the simulation modeling methodology and the underpinnings of discrete-event systems, as well as the relevant underlying probability, statistics, stochastic processes, input analysis, model validation and output analysis. All simulation-related concepts are illustrated in numerous Arena examples, encompassing production lines, manufacturing and inventory systems, transportation systems, and computer information systems in networked settings. Chapter 13.3.3 is on coal loading operations on barges/tugboats.

Tayfur Altiok; Benjamin Melamed [Rutgers University, NJ (United States). Department of Industrial and Systems Engineering

2007-06-15

241

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

242

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

NSDL National Science Digital Library

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

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

2003-08-01

243

Modeling, simulation and optimization of  

E-print Network

and simulation accuracy is key for performance characterization ­ Impact of low level architectural details · 1394 · USB ...and more TM-xxxx D$ I$ TriMedia CPU DEVICE IP BLOCK DEVICE IP BLOCK DEVICE IP BLOCK become the key issue · GALS: Globally Asynchronous Locally Synchronous · Many types of interconnects

Bogliolo, Alessandro

244

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

245

Modeling low-flow bedrock springs providing ecological habitats with climate change scenarios  

NASA Astrophysics Data System (ADS)

Groundwater discharge areas, including low-flow bedrock aquifer springs, are ecologically important and can be impacted by climate change. The development of and results from a groundwater modeling study simulating fractured bedrock spring flow are presented. This was conducted to produce hydrological data for an ecohydrological study of an endangered species, Allegheny Mountain Dusky Salamanders (Desmognathus ochrophaeus), in southern Quebec, Canada. The groundwater modeling approach in terms of scale and complexity was strongly driven by the need to produce hydrological data for the related ecohydrological modeling. Flows at four springs at different elevations were simulated for recent past conditions (2006-2010) and for reference (1971-2000) and future (2041-2070) periods using precipitation and temperature data from ten climate scenarios. Statistical analyses of spring flow parameters including activity periods and duration of flow were conducted. Flow rates for the four simulated springs, located at different elevations, are predicted to increase between 2% and 46% and will be active (flowing) 1-2% longer in the future. A significant change (predominantly an increase) looking at the seasonality of the number of active days occurs in the winter (2-4.9%) and spring seasons (-0.6-6.5%). Greatest flow rates were produced from springs at elevations where sub-horizontal fractures intersect the ground surface. These results suggest an intensification of the spring activity at the study site in context of climate change by 2050, which provides a positive habitat outlook for the endangered salamanders residing in the springs for the future.

Levison, J.; Larocque, M.; Ouellet, M. A.

2014-07-01

246

A theory of forest dynamics: The ecological implications of forest succession models  

Microsoft Academic Search

This book is a synthesis of what has been learned about ecological succession from the process of developing the models for the various systems which typically consisted of starting with the FORET model (an Appalachian deciduous forest). Modifying, testing, and applying such a model is the core of this work. Contents, abridged: Forest succession. Computer models of forest succession. Patch

H. H. Shugart

1984-01-01

247

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

248

Modeling and Simulating Electronic Textile Applications  

E-print Network

1 Modeling and Simulating Electronic Textile Applications Thomas Martin, Mark Jones, Joshua Edmison@vt.edu Abstract-- This paper describes our experiences with a simulation environment for electronic textiles to the design of electronic textiles, including the physical environment they will be used in, the behavior

249

Multisite stochastic model for rainfall simulation  

Microsoft Academic Search

In the context of flood management , it is useful and reliable to provide scenarios by rainfall simulation, in order to overcome data limitations in terms of time and spatial resolution. This paper summarizes a methodology for a space-time simulation of hourly rainfall. The first step is to fit a generalized linear model (GLM) in order to generate daily rainfall

V. Montesarchio; F. Napolitano

2009-01-01

250

Modeling and simulating electronic textile applications  

Microsoft Academic Search

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

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

2004-01-01

251

Do Ecological Niche Model Predictions Reflect the Adaptive Landscape of Species?: A Test Using Myristica malabarica Lam., an Endemic Tree in the Western Ghats, India  

E-print Network

Ecological niche models (ENM) have become a popular tool to define and predict the “ecological niche” of a species. An implicit assumption of the ENMs is that the predicted ecological niche of a species actually reflects the adaptive landscape...

Nagaraju, Shivaprakash K.; Gudasalamani, Ravikanth; Barve, Narayani; Ghazoul, Jaboury; Narayangowda, Ganeshaiah Kotiganahalli; Ramanan, Uma Shaanker

2013-11-29

252

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...

253

Simultaneous estimation of both hydrological and ecological parameters in an ecohydrological model by assimilating microwave signal  

NASA Astrophysics Data System (ADS)

To improve the skill of reproducing land-atmosphere interactions in weather, seasonal, and climate prediction systems, it is necessary to simulate correctly and simultaneously the surface soil moisture (SSM) and terrestrial biomass in land surface models. Despite the performance of hydrological and ecosystem models depends highly on parameter calibration, a method for parameter estimation in ungauged areas has yet to be established. We develop an autocalibration system that can simultaneously estimate both hydrological and ecological parameters by assimilating a microwave signal that is sensitive to both SSM and terrestrial biomass. This system comprises a hydrological model that has a physically based, sophisticated soil hydrology scheme, a dynamic vegetation model that can estimate vegetation growth and senescence, and a radiative transfer model that can convert land surface condition into brightness temperatures in the microwave region. By assimilating microwave signals from the Advanced Microwave Scanning Radiometer for Earth Observing System, the system simultaneously optimizes the parameters of these models. We test this approach at three in situ observation sites under different hydroclimatic conditions. Estimated SSM exhibits good agreement with ground-based in situ observed SSM, and estimated leaf area index (LAI) is also improved by the optimization, compared with satellite-observed LAI. The root-mean-square error of SSM and LAI at all sites, estimated by the model with optimized parameters, is much less than that estimated by the model with default parameters. Using microwave satellite brightness temperature data sets, this system offers the potential to calibrate parameters of both hydrological and ecosystem models globally.

Sawada, Yohei; Koike, Toshio

2014-07-01

254

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

255

Mathematical Model Development and Simulation Support  

NASA Technical Reports Server (NTRS)

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

Francis, Ronald C.; Tobbe, Patrick A.

2000-01-01

256

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

257

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

258

DEVELOPMENT OF THE ADVANCED UTILITY SIMULATION MODEL  

EPA Science Inventory

The paper discusses the development of the Advanced Utility Simulation Model (AUSM), developed for the National Acid Precipitation Assessment Program (NAPAP), to forecast air emissions of pollutants from electric utilities. USM integrates generating unit engineering detail with d...

259

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...

260

Theory, modeling, and simulation annual report, 1992  

SciTech Connect

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

Not Available

1993-05-01

261

A simulator for spatially extended kappa models  

PubMed Central

Summary: Spatial Kappa is a simulator of models written in a variant of the rule-based stochastic modelling language Kappa, with spatial extensions. Availability: The spatial kappa simulator is an open-source project licensed under the LGPLv3, with Java source, binaries and manual available at http://github.com/lptolik/SpatialKappa. Contact: oksana.sorokina@ed.ac.uk Supplementary information: Supplementary data are available at Bioinformatics online. PMID:24021382

Sorokina, Oksana; Sorokin, Anatoly; Douglas Armstrong, J.; Danos, Vincent

2013-01-01

262

Agent-based modeling to simulate the dengue spread  

NASA Astrophysics Data System (ADS)

In this paper, we introduce a novel method ABM in simulating the unique process for the dengue spread. Dengue is an acute infectious disease with a long history of over 200 years. Unlike the diseases that can be transmitted directly from person to person, dengue spreads through a must vector of mosquitoes. There is still no any special effective medicine and vaccine for dengue up till now. The best way to prevent dengue spread is to take precautions beforehand. Thus, it is crucial to detect and study the dynamic process of dengue spread that closely relates to human-environment interactions where Agent-Based Modeling (ABM) effectively works. The model attempts to simulate the dengue spread in a more realistic way in the bottom-up way, and to overcome the limitation of ABM, namely overlooking the influence of geographic and environmental factors. Considering the influence of environment, Aedes aegypti ecology and other epidemiological characteristics of dengue spread, ABM can be regarded as a useful way to simulate the whole process so as to disclose the essence of the evolution of dengue spread.

Deng, Chengbin; Tao, Haiyan; Ye, Zhiwei

2008-10-01

263

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...

264

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

265

Adaptive multiscale model for simulating cardiac conduction  

PubMed Central

We present a multiscale model and an adaptive numerical scheme for simulating cardiac action potential propagation along a linear strand of heart muscle cells. This model couples macroscale partial differential equations posed over the tissue to microscale equations posed over discrete cellular geometry. The microscopic equations are used only near action potential wave fronts, and the macroscopic equations are used everywhere else. We study the effects of gap-junctional and ephaptic coupling on conduction in the multiscale model and its fully macroscale and fully microscale analogues. Our simulations reveal that the adaptive multiscale model accurately reproduces the action potential wave forms and wave speeds of the fully microscale model. They also demonstrate that, at low gap-junctional conductivities, the accuracy of fully macroscale simulations is sensitive to numerical grid spacing. Moreover, adaptive multiscale simulations capture the effect of ephaptic coupling, whereas fully macroscale simulations do not. We propose two ways of generalizing our multiscale model to higher dimensions, and we argue that such generalizations may be necessary to obtain accurate three-dimensional simulations of cardiac conduction in certain pathophysiological parameter regimes. PMID:20671202

Hand, Paul E.; Griffith, Boyce E.

2010-01-01

266

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

PubMed Central

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

Skelly, Chris; Weinstein, Phil

2003-01-01

267

Gecko: a continuous 2D world for ecological modeling.  

PubMed

An individual-based simulation system, named Gecko, is presented for modeling multiple species at multiple trophic levels, on a spatially explicit, continuous two-dimensional landscape. Biologically motivated rules are specified at an individual level, and resulting behaviors are observed at an ecosystem level. Individuals are represented by circles with free range on a resource-producing plane. These circles grow allometrically with biomass of fixed resources. Resource acquisition behaviors include competition by area overlap for producers, and movement based on perception and intent. Individual-level energetics are explicitly modeled with inefficient assimilation, resource transformation, and allometrically specified metabolic costs. Individual growth and reproduction requires a history of successful resource acquisition. Terrestrial producer, herbivore, and carnivore species classes are included, extensible to further classes. A grassland food chain model of "plants," "grasshoppers," and "spiders" is used to demonstrate ecosystem-level results of given individual-level behaviors. Ecosystem-level behaviors include a trophic cascade of indirect carnivore-producer interaction effects; stable persistence of all populations; a near-realistic biomass pyramid; and spatial competition and coexistence of multiple producer species. Initial Gecko results show promise for application in both theoretical and natural ecosystem modeling. PMID:9385732

Booth, G

1997-01-01

268

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.

0000-00-00

269

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

NASA Astrophysics Data System (ADS)

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

Huang, Fang; Wang, Ping; Qi, Xin

2014-11-01

270

Simulating Energy, Water and Carbon Fluxes at the Shortgrass Steppe Long Term Ecological Research (LTER) Site  

NASA Astrophysics Data System (ADS)

Coupled atmospheric-biospheric models are a particularly valuable tool for studying the potential effects of land-use and land-cover changes on the near-surface atmosphere since the atmosphere and biosphere are allowed to dynamically interact through the surface and canopy energy balance. GEMRAMS is a coupled atmospheric-biospheric model comprised of an atmospheric model, RAMS, and an ecophysiological process-based model, GEMTM. In the first part of this study, the soil-vegetation-atmosphere-transfer (SVAT) scheme, LEAF2, from RAMS, coupled with GEMTM, are used to simulate energy, water and carbon fluxes over different cropping systems (winter wheat and irrigated corn) and over a mixed C3/C4 shortgrass prairie located at the USDA-ARS Central Plains Experimental Range near Nunn, Colorado, the LTER Shortgrass Steppe site. The new SVAT scheme, GEMLEAF, is forced with air temperature and humidity, wind speed and photosynthetic active radiation (PAR). Calculated canopy temperature and relative humidity, soil moisture and temperature and PAR are used to compute sunlit/shaded leaf photosynthesis (for C3 and C4 plant types) and respiration. Photosynthate is allocated to leaves, shoots, roots and reproductive organs with variable partition coefficients, which are functions of soil water conditions. As water stress increases, the fraction of photosynthate allocated to root growth increases. Leaf area index (LAI) is estimated from daily leaf biomass growth, using the vegetation-prescribed specific leaf area. Canopy conductance, computed and based on photosynthesis and relative humidity, is used to calculate latent heat flux. Simulated energy and CO2 fluxes are compared to observations collected using Bowen ratio flux towers during two growing seasons. Seasonality of the fluxes reflecting different plant phenologies agrees well with the observed patterns. In the second part of this study, simulations for two clear days are performed with GEMRAMS over a model domain centered at the SGS site. Simulated spatial differences in the energy fluxes can be associated with the highly heterogeneous landscape in this area.

Beltran-Przekurat, A. B.; Pielke, R. A.; Morgan, J. A.; Burke, I. C.

2005-12-01

271

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

272

Multi-Criteria Assessment of Ecological Process Models  

E-print Network

Ford Quantitative Ecology and Resource Management Program, and College of Forest Resources, Box 352100 to reveal conflicts in ability to achieve simultaneously different collections of criteria. POMAC improves aspects of WHORL's functioning: three stand height distribution criteria, three #12;03/11/98 3 crown

Washington at Seattle, University of

273

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;

274

Ecological modeling for the extrapolation of ecotoxicological effects measured during in situ assays in Gammarus.  

PubMed

Evaluating the effects of chemical contamination on populations and ecological communities still constitutes a challenging necessity in environmental management. However, the toxic effects of contaminants are commonly measured by means of organism-level responses. Linking such effects measures with ecological models is a promising way to determine population-level impacts. In this way, population models are currently increasingly used in predictive risk assessment procedures, but their use in environmental diagnostic framework remains limited due to their lack of ecological realism. The present study with the crustacean Gammarus fossarum, a sentinel species in freshwater monitoring, combines a dual field and laboratory experimental approach with a population modeling framework. In this way, we developed an ecologically relevant periodic matrix population model for Gammarus. This model allowed us to capture the population dynamics in the field, and to understand the particular pattern of demographic sensitivities induced by Gammarus life-history phenology. The model we developed provided a robust population-level assessment of in situ-based effects measures recorded during a biomonitoring program on a French watershed impacted by past mining activities. Thus, our study illustrates the potential of population modeling when seeking to decipher the role of environmental toxic contamination in ecological perturbations. PMID:24805228

Coulaud, Romain; Geffard, Olivier; Coquillat, Amandine; Quéau, Hervé; Charles, Sandrine; Chaumot, Arnaud

2014-06-01

275

Trimming an aircraft model for flight simulation  

NASA Technical Reports Server (NTRS)

Real-time piloted aircraft simulations with digital computers have been performed at Ames Research Center (ARC) for over two decades. For the simulation of conventional aircraft models, the establishment of initial vehicle and control orientations at various operational flight regimes has been adequately handled by either analog techniques or simple inversion processes. However, exotic helicopter configurations have been introduced recently that require more sophisticated techniques because of their expanded degrees of freedom and environmental vibration levels. At ARC, these techniques are used for the backward solutions to real-time simulation models as required for the generation of trim points. These techniques are presented in this paper with examples from a blade-element helicopter simulation model.

Mcfarland, Richard E.

1987-01-01

276

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

277

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

E-print Network

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

Arhonditsis, George B.

2013-01-01

278

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

279

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

E-print Network

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

Wu, Jianguo "Jingle"

280

SIMULATION MODEL, DRAINMOD-N II  

Microsoft Academic Search

A two-step global sensitivity analysis was conducted for the nitrogen simulation model DRAINMOD-N II to assess the sensitivity of model predictions of NO3-N losses with drainage water to various model inputs. Factors screening using the LH-OAT (Latin hypercube sampling - one at a time) sensitivity analysis method was performed as a first step considering 48 model parameters; then a variance-based

X. Wang; M. A. Youssef; R. W. Skaggs; J. D. Atwood; J. R. Frankenberger

2005-01-01

281

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

282

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...

283

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

284

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

285

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

286

Parallel methods for the flight simulation model  

SciTech Connect

The Advanced Computer Applications Center (ACAC) has been involved in evaluating advanced parallel architecture computers and the applicability of these machines to computer simulation models. The advanced systems investigated include parallel machines with shared. memory and distributed architectures consisting of an eight processor Alliant FX/8, a twenty four processor sor Sequent Symmetry, Cray XMP, IBM RISC 6000 model 550, and the Intel Touchstone eight processor Gamma and 512 processor Delta machines. Since parallelizing a truly efficient application program for the parallel machine is a difficult task, the implementation for these machines in a realistic setting has been largely overlooked. The ACAC has developed considerable expertise in optimizing and parallelizing application models on a collection of advanced multiprocessor systems. One of aspect of such an application model is the Flight Simulation Model, which used a set of differential equations to describe the flight characteristics of a launched missile by means of a trajectory. The Flight Simulation Model was written in the FORTRAN language with approximately 29,000 lines of source code. Depending on the number of trajectories, the computation can require several hours to full day of CPU time on DEC/VAX 8650 system. There is an impetus to reduce the execution time and utilize the advanced parallel architecture computing environment available. ACAC researchers developed a parallel method that allows the Flight Simulation Model to be able to run in parallel on the multiprocessor system. For the benchmark data tested, the parallel Flight Simulation Model implemented on the Alliant FX/8 has achieved nearly linear speedup. In this paper, we describe a parallel method for the Flight Simulation Model. We believe the method presented in this paper provides a general concept for the design of parallel applications. This concept, in most cases, can be adapted to many other sequential application programs.

Xiong, Wei Zhong; Swietlik, C.

1994-06-01

287

Estimating solar radiation for plant simulation models  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

288

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

1996-01-01

289

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

290

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

291

Atomic Models for Non-LTE Simulations  

Microsoft Academic Search

We describe our atomic physics data base for use in future non-LTE simulations of the solar atmosphere. Self-consistent atmospheric models require a treatment that is valid from the photosphere to the corona. We therefore need a vast array of atomic data from many elements spanning the widest range of ion stages. We have therefore been developing atomic models of the

D. Tod Woods; John I. Castor; George H. Fisher

1997-01-01

292

Dynamic centrifugal compressor model for system simulation  

Microsoft Academic Search

A dynamic model of a centrifugal compressor capable of system simulation in the virtual test bed (VTB) computational environment is presented. The model is based on first principles, i.e. the dynamic performance including the losses is determined from the compressor geometry and not from the experimentally determined characteristic performance curves. In this study, the compressor losses, such as incidence and

Wei Jiang; Jamil Khan; Roger A. Dougal

2006-01-01

293

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

294

Metabolic ecology.  

PubMed

Ecological theory that is grounded in metabolic currencies and constraints offers the potential to link ecological outcomes to biophysical processes across multiple scales of organization. The metabolic theory of ecology (MTE) has emphasized the potential for metabolism to serve as a unified theory of ecology, while focusing primarily on the size and temperature dependence of whole-organism metabolic rates. Generalizing metabolic ecology requires extending beyond prediction and application of standardized metabolic rates to theory focused on how energy moves through ecological systems. A bibliometric and network analysis of recent metabolic ecology literature reveals a research network characterized by major clusters focused on MTE, foraging theory, bioenergetics, trophic status, and generalized patterns and predictions. This generalized research network, which we refer to as metabolic ecology, can be considered to include the scaling, temperature and stoichiometric models forming the core of MTE, as well as bioenergetic equations, foraging theory, life-history allocation models, consumer-resource equations, food web theory and energy-based macroecology models that are frequently employed in ecological literature. We conclude with six points we believe to be important to the advancement and integration of metabolic ecology, including nomination of a second fundamental equation, complementary to the first fundamental equation offered by the MTE. PMID:24028511

Humphries, Murray M; McCann, Kevin S

2014-01-01

295

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

296

Power electronics system modeling and simulation  

SciTech Connect

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

Lai, Jih-Sheng

1994-12-31

297

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

298

Multi-Formalism Modelling and Simulation: Application to Cardiac Modelling  

E-print Network

oxygen consumption and blood irrigation on the cardiac muscle, known as is- chemia. Different typesMulti-Formalism Modelling and Simulation: Application to Cardiac Modelling A. Defontaine, A Cardiovascular modelling has been a major research subject for the last decades. Different cardiac models have

Paris-Sud XI, Université de

299

Hydrological validation of multifractal rainfall simulation models  

NASA Astrophysics Data System (ADS)

The observed scaling invariance properties of rainfall time series have often been put forward to justify the choice of multifractal (scaling) models for rainfall stochastic modelling. These models are nevertheless seldom validated on real hydrological applications. Two types of multifractal models - the first one with a Log-Poisson generator and the second one with a uniform generator - were calibrated on a 8 year point rainfall series with a five minute time step. The results obtained with the rainfall series simulated with these models on two hydrological applications (the computation of intensity-duration-frequency, IDF, curves and the conception of a urban drainage storage volume) were compared with those obtained with the original measured rainfall series. The disagreements reveal some limitations of the multifractal models. On the one hand, using the vocabulary of the multifractalists, the models are calibrated on the basis of the statistical properties of the simulated undressed series while the IDF curves are computed on the dressed series. The statistical properties of both types of series clearly differ if a canonical model is used : here the model with the Log-Poisson generator. On the other hand, the optimal dimensions of the storage volume depend on the shape of the hyetographs. The discordances between the volumes obtained with the simulated or measured rainfall series indicate that the temporal structure of the simulated rainfall intensity series (i.e. the shapes of the simulated hyetographs) are not comparable with the one of the measured series. As a conclusion, multifractal models appear to reproduce accuratly only some of the properties of the real measured series. Their appropriateness should not be a priori asserted but verified for each considered application.

Mouhous, N.; Gaume, E.; Andrieu, H.

2003-04-01

300

Using historical and projected future climate model simulations as drivers of agricultural and biological models (Invited)  

NASA Astrophysics Data System (ADS)

Climate model evaluation is frequently performed as a first step in analyzing climate change simulations. Atmospheric scientists are accustomed to evaluating climate models through the assessment of model climatology and biases, the models' representation of large-scale modes of variability (such as ENSO, PDO, AMO, etc) and the relationship between these modes and local variability (e.g. the connection between ENSO and the wintertime precipitation in the Southeast US). While these provide valuable information about the fidelity of historical and projected climate model simulations from an atmospheric scientist's point of view, the application of climate model data to fields such as agriculture, ecology and biology may require additional analyses focused on the particular application's requirements and sensitivities. Typically, historical climate simulations are used to determine a mapping between the model and observed climate, either through a simple (additive for temperature or multiplicative for precipitation) or a more sophisticated (such as quantile matching) bias correction on a monthly or seasonal time scale. Plants, animals and humans however are not directly affected by monthly or seasonal means. To assess the impact of projected climate change on living organisms and related industries (e.g. agriculture, forestry, conservation, utilities, etc.), derivative measures such as the heating degree-days (HDD), cooling degree-days (CDD), growing degree-days (GDD), accumulated chill hours (ACH), wet season onset (WSO) and duration (WSD), among others, are frequently useful. We will present a comparison of the projected changes in such derivative measures calculated by applying: (a) the traditional temperature/precipitation bias correction described above versus (b) a bias correction based on the mapping between the historical model and observed derivative measures themselves. In addition, we will present and discuss examples of various application-based climate model evaluations, such as: (a) agricultural crop yield estimates and (b) species population viability estimates modeled using observed climate data vs. historical climate simulations.

Stefanova, L. B.

2013-12-01

301

Simulation Modeling of Software Development Processes  

NASA Technical Reports Server (NTRS)

A simulation modeling approach is proposed for the prediction of software process productivity indices, such as cost and time-to-market, and the sensitivity analysis of such indices to changes in the organization parameters and user requirements. The approach uses a timed Petri Net and Object Oriented top-down model specification. Results demonstrate the model representativeness, and its usefulness in verifying process conformance to expectations, and in performing continuous process improvement and optimization.

Calavaro, G. F.; Basili, V. R.; Iazeolla, G.

1996-01-01

302

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

USGS Publications Warehouse

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

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

2014-01-01

303

Integrating ecological risk assessments across levels of organization using the Franklin-Noss model of biodiversity  

SciTech Connect

Wildlife toxicologists pioneered methodologies for assessing ecological risk to nontarget species. Historically, ecological risk assessments (ERAS) focused on a limited array of species and were based on a relatively few population-level endpoints (mortality, reproduction). Currently, risk assessment models are becoming increasingly complex that factor in multi-species interactions (across trophic levels) and utilize an increasingly diverse number of ecologically significant endpoints. This trend suggests the increasing importance of safeguarding not only populations of individual species, but also the overall integrity of the larger biotic systems that support them. In this sense, ERAs are in alignment with Conservation Biology, an applied science of ecological knowledge used to conserve biodiversity. A theoretical conservation biology model could be incorporated in ERAs to quantify impacts to biodiversity (structure, function or composition across levels of biological organization). The authors suggest that the Franklin-Noss model for evaluating biodiversity, with its nested, hierarchical approach, may provide a suitable paradigm for assessing and integrating the ecological risk that chemical contaminants pose to biological systems from the simplest levels (genotypes, individual organisms) to the most complex levels of organization (communities and ecosystems). The Franklin-Noss model can accommodate the existing ecotoxicological database and, perhaps more importantly, indicate new areas in which critical endpoints should be identified and investigated.

Brugger, K.E.; Tiebout, H.M. III [DuPont Agricultural Products, Wilmington, DE (United States). Experimental Station; [West Chester Univ., West Chester, PA (United States). Dept. of Biology

1994-12-31

304

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

305

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

306

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

307

Modeling Florida panther movements in response to human attributes of the landscape and ecological settings  

Microsoft Academic Search

This paper describes the development and results of an individual-based spatially explicit model created to assist in the potential reintroduction of the Florida panther (Puma concolor coryi) to northern Florida, an area within its former range. The PANTHER model was created to incorporate human attributes of the landscape with ecological attributes to evaluate and identify landscape features and conservation strategies

Patricia C Cramer; Kenneth M Portier

2001-01-01

308

Trauma Outcome Process Assessment (TOPA) Model: An Ecological Paradigm for Treating Traumatized Sexually Abusive Youth  

Microsoft Academic Search

Discussed is a comprehensive, ecologically based paradigm applicable across cultures and created to assess the effects of abusive traumatic experiences, the Trauma Outcome Process Assessment (TOPA) model (Rasmussen, 1999, 2004, 2007; Rasmussen, Burton, & Christopherson, 1992). The TOPA model comprehensively assesses the risk and protective factors and trauma outcomes that contribute to self-destructive and\\/or abusive behavior in youth. TOPA interventions

Lucinda A. Rasmussen

2012-01-01

309

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...

310

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

PubMed Central

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

311

Common modeling system for digital simulation  

NASA Technical Reports Server (NTRS)

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

Painter, Rick

1994-01-01

312

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

313

Ecology, 86(4), 2005, pp. 10231033 2005 by the Ecological Society of America  

E-print Network

1023 Ecology, 86(4), 2005, pp. 1023­1033 2005 by the Ecological Society of America MATRIX STRUCTURE isolation. We hypothesized that the predictive power of models that relate patch immigration rate to patch and isolation accounted for up to 75% of the variation in patch immigration rate in the simulation study

314

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

PubMed Central

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

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

2015-01-01

315

Balancing ecological complexity in predictive models: a reassessment of risk models in the mountain pine beetle system  

Microsoft Academic Search

Summary 1. The nature of ecological risk assessment is to predict the probability of an event, such as extinc- tion or invasion, in a location where the event has rarely occurred. This typically requires developing risk models from data on events in different locations. One perplexing challenge in developing these models is to find the optimal balance of model complexity

William A. Nelson; Alex Potapov; Mark A. Lewis; Anina E. Hundsdörfer; Fangliang He

2008-01-01

316

Testing turbulent closure models with convection simulations  

NASA Astrophysics Data System (ADS)

We compare simple analytical closure models of homogeneous turbulent Boussinesq convection for stellar applications with three-dimensional simulations. We use turbulent closure models to compute the Reynolds stresses and the turbulent heat flux as functions of rotation rate measured by the Taylor number. We also investigate cases with varying angles between the angular velocity and gravity vectors, corresponding to locating the computational domain at different latitudes ranging from the pole to the equator of the star. We perform three-dimensional numerical simulations in the same parameter regimes for comparison. The free parameters appearing in the closure models are calibrated by two fitting methods using simulation data. A unique determination of the closure parameters is possible only in the non-rotating case or when the system is placed at the pole. In the other cases the fit procedures yield somewhat differing results. The quality of the closure is tested by substituting the resulting coefficients back into the closure model and comparing with the simulation results. To eliminate the possibilities that the results obtained depend on the aspect ratio of the simulation domain or suffer from too small Rayleigh numbers we performed runs varying these parameters. The simulation data for the Reynolds stress and heat fluxes broadly agree with previous compressible simulations. The closure works fairly well with slow and fast rotation but its quality degrades for intermediate rotation rates. We find that the closure parameters depend not only on rotation rate but also on latitude. The weak dependence on Rayleigh number and on the aspect ratio of the domain indicates that our results are generally valid.

Snellman, J. E.; Käpylä, P. J.; Käpylä, M. J.; Rheinhardt, M.

2015-01-01

317

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

318

DYNAMIC MODEL DATA DYNAMIC SIMULATION ,MODELING  

E-print Network

/B/C/D Propane condenser Table 4.1.4 Heat exchanger Unit Operations Unit Operations (Model Name) Description E LINK ,HYSIS SOFTWARE PID CONTROL SYSTEM . REFRIGERATOR SYSTEM SAMPLE . 2 , STAND to effect the pressure than one of cooling water exchanger. Figure 4.2.5 Data for E-2512A/B Figure 4

Hong, Deog Ki

319

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

320

Simulation and modeling for military air operations  

NASA Astrophysics Data System (ADS)

The Joint Forces Air Component Commander (JFACC) in military air operations controls the allocation of resources (wings, squadrons, air defense systems, AWACS) to different geographical locations in the theater of operations. The JFACC mission is to define a sequence of tasks for the aerospace systems at each location, and providing feedback control for the execution of these tasks in the presence of uncertainties and a hostile enemy. Honeywell Labs has been developing an innovative method for control of military air operations. The novel model predictive control (MPC) method extends the models and optimization algorithms utilized in traditional model predictive control systems. The enhancements include a tasking controller and, in a joint effort with USC, a probabilistic threat/survival map indicating high threat regions for aircraft and suggesting optimal routes to avoid these regions. A simulation/modeling environment using object-oriented methodologies has been developed to serve as an aide to demonstrate the value of MPC and facilitate its development. The simulation/modeling environment is based on an open architecture that enables the integration, evaluation, and implementation of different control approaches. The simulation offers a graphical user interface displaying the battlefield, the control performance, and a probability map displaying high threat regions. This paper describes the features of the different control approaches and their integration into the simulation environment.

Kreichauf, Ruth D.; Bedros, Saad; Ateskan, Yusuf; Hespanha, Joao; Kizilocak, Hakan

2001-09-01

321

Simulation tools for optical resist models (STORM)  

NASA Astrophysics Data System (ADS)

STORM is a collection of software tools that provide a general numerical framework for tackling nonlinear model-equations encountered in photoresist process modeling. Post exposure bake models based on a moving-boundary acid transport concept that incorporates transient free-volume generation and densification are used as test vehicles for the simulation tools. The numerical tools are also used to demonstrate a moving-boundary silylation simulator which includes polymer relaxation, reaction-dependent silylating agent diffusivity, and stress-dependent retardation of the reaction rate. Three key elements of the numerical algorithms include: (1) A second order implicit time discretization algorithm with variable timestep control for stability and accuracy requirements. This algorithm known as BDF2 is well suited for highly nonlinear partial differential equations; (2) An improved space discretization finite element algorithm which uses method of partial variable substitution to reduce the number of system variables; (3) Miller's Krylov Subspace Iteration Convergence Accelerator which is used to speed up convergence of the Newton iterations. The Krylov accelerator achieves simulation runs of less that 5 minutes using realistic resist parameters. The same simulation can take more than a day when the Krylov accelerator is not used. A novel free-volume PEB model is presented. The development of this model was driven by challenge to explain new experimental data from collaborators at the University of Texas at Austin. The model is able to link the relief image formation to the mechanical and chemical properties of the resist polymer and is capable of simulating the resist shrinkage upon baking. The two dimensional silylation simulator is the first of its kind to include stress effects. Silylation simulation results illustrate the interplay of the various physical parameters in determining final silylation depth and sidewall angle as a function of exposure and silylation conditions and the film's material properties. Principal examples in 193nm resist modeling and characterization and especially the ability to study influence of chemical structure and properties of photoacid generators on lithographic performance of 193nm resist is presented. The simulator is used to quantify acid generation efficiency, reaction efficiency and diffusion properties of the PAGs, and their effects on resist performance.

Croffie, Ebo Harry

322

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

323

Experimental Noise Injection in Simulated Model Signals  

NASA Astrophysics Data System (ADS)

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

Khan, Tariq; Udpa, Lalita; Udpa, Satish

2011-06-01

324

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

E-print Network

model. Our analysis has general implications for all tropical rain forests in that it suggests in tropical rain forests (Hubbell et al., 1999; Svenning, 1999). Indeed, Tilman (1994) suggests that his model that it is not appropriate for the simulation of tropical rain forest tree species dy- namics.WepresentanadaptationofTilman's

Maini, Philip K.

325

Can we reach consensus between marine ecological models and DEB theory? A look at primary producers  

NASA Astrophysics Data System (ADS)

In the last decades we have witnessed an explosion in marine modeling efforts, both at the development and application levels. A general agreement is expected between ecological models and metabolic theories, and one should be able to use ideas and principles from both views. Nevertheless, there are marked differences that can vary from differences in formulation of processes to baseline assumptions. So far, efforts to reconcile these models of natural systems have been limited. Here, we critically compare ERSEM (European Regional Seas Ecosystem Model), a state of the art ecological model in marine biogeochemical modeling, with a DEB (Dynamic Energy Budget) model (based on the metabolic theory DEB), highlighting similarities and showing where the approaches differ. This study focuses on primary producers and is driven by two main questions: (1) Is it possible to harmonize the philosophy and structure of models like ERSEM with the general scope of unifying metabolic theories such as DEB? (2) Can we bring the current paradigms in ecological modeling for marine communities to consensus with metabolic theories? We analyze the links between the underling processes in the DEB and ERSEM models. We found that the processes of assimilation and mobilization are the most difficult to reconcile between the two models. However, we also find a number of clear analogies between the parameters, state variables and fluxes of the two models, which allow for the transference of knowledge between them.

Marques, Gonçalo M.; Mateus, Marcos; Domingos, Tiago

2014-11-01

326

[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

327

Ongoing ecological divergence in an emerging genomic model.  

PubMed

Much of Earth's biodiversity has arisen through adaptive radiation. Important avenues of phenotypic divergence during this process include the evolution of body size and life history (Schluter 2000). Extensive adaptive radiations of cichlid fishes have occurred in the Great Lakes of Africa, giving rise to behaviours that are remarkably sophisticated and diverse across species. In Tanganyikan shell-brooding cichlids of the tribe Lamprologini, tremendous intraspecific variation in body size accompanies complex breeding systems and use of empty snail shells to hide from predators and rear offspring. A study by Takahashi et al. (2009) in this issue of Molecular Ecology reveals the first case of genetic divergence between dwarf and normal-sized morphs of the same nominal lamprologine species, Telmatochromis temporalis. Patterns of population structure suggest that the dwarf, shell-dwelling morph of T. temporalis might have arisen from the normal, rock-dwelling morph independently in more than one region of the lake, and that pairs of morphs at different sites may represent different stages early in the process of ecological speciation. The findings of Takahashi et al. are important first steps towards understanding the evolution of these intriguing morphs, yet many questions remain unanswered about the mating system, gene flow, plasticity and selection. Despite these limitations, descriptive work like theirs takes on much significance in African cichlids due to forthcoming resources for comparative genomics. PMID:19570143

Arnegard, Matthew E

2009-07-01

328

Ongoing Ecological Divergence in an Emerging Genomic Model  

PubMed Central

Much of Earth’s biodiversity has arisen through adaptive radiation. Important avenues of phenotypic divergence during this process include the evolution of body size and life history (Schluter 2000). Extensive adaptive radiations of cichlid fishes have occurred in the Great Lakes of Africa, giving rise to behaviors that are remarkably sophisticated and diverse across species. In Tanganyikan shell-brooding cichlids of the tribe Lamprologini, tremendous intraspecific variation in body size accompanies complex breeding systems and use of empty snail shells to hide from predators and rear offspring. A study by Takahashi et al. (2009) in this issue of Molecular Ecology reveals the first case of genetic divergence between dwarf and normal-sized morphs of the same nominal lamprologine species, Telmatochromis temporalis. Patterns of population structure suggest that the dwarf, shell-dwelling morph of T. temporalis might have arisen from the normal, rock-dwelling morph independently in more than one region of the lake, and that pairs of morphs at different sites may represent different stages early in the process of ecological speciation. The findings of Takahashi et al. are important first steps toward understanding the evolution of these intriguing morphs, yet many questions remain unanswered about the mating system, gene flow, plasticity, and selection. Despite these limitations, descriptive work like theirs takes on much significance in African cichlids due to forthcoming resources for comparative genomics. PMID:19570143

Arnegard, Matthew E.

2009-01-01

329

Simulation Modeling on the Macintosh using STELLA.  

ERIC Educational Resources Information Center

Describes a new software package for the Apple Macintosh computer which can be used to create elaborate simulation models in a fraction of the time usually required without using a programming language. Illustrates the use of the software which relates to water usage. (TW)

Costanza, Robert

1987-01-01

330

Microstructural Evolution: modeling, simulation, and experiment  

NASA Astrophysics Data System (ADS)

Mesoscale simulation of phase coarsening remains as an active and important topic in materials physics. Classical mean-field theories, as originally formulated by Lifshitz and Slyozov and by Wagner (LSW), exclude all interactions among coarsening particles and ignores local environmental information. Mean-field coarsening rates and predictions of particle size distributions differ markedly from experiment. We proposed a model that includes diffusion Debye screening physics to describe first-order interactions among particles. An efficient multiparticle diffusion model is employed to simulate the dynamics of late-stage phase coarsening. Local environmental information, correlations, and particle interactions within each coarsening "locale" are included in the simulations. These studies reveal that the observed "fluctuations" from mean-field behavior are caused by their differing environments, and not by thermal noise. Multiplicative noise, nonetheless, provides a sound analytical basis to describe microstructural "fluctuations" during late-stage coarsening. The Fokker-Planck equation for the particle size distribution and its asymptotic solution were obtained. The results derived from modeling and simulation are found to be in good agreement with experimental observations obtained for a model alloy system.

Wang, Kegang; Glicksman, Martin E.; Rajan, K.

2004-03-01

331

Biological Invasion: Observations, Theory, Models, Simulations  

E-print Network

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

332

TIRE MODELS IN AIRCRAFT LANDING GEAR SIMULATION  

Microsoft Academic Search

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

M. T. P. van Slagmaat

1992-01-01

333

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

334

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

335

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.

336

Modeling and Simulation Information Analysis Center  

NSDL National Science Digital Library

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

337

Byrd Polar Research Center Climate Model Simulation  

NSDL National Science Digital Library

This set of animations and interactive simulations from the Byrd Polar Research Center at Ohio State University helps students develop an understanding of models used to understand the Earth System. Students consider the types of data that need to be included in a climate model, looking at inputs and outputs as well as variables, such as land surface, and how to measure changes of different parts of Earth's surface over time.

Byrd Polar Research Center

338

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

PubMed

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

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

2015-02-01

339

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

SciTech Connect

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

Kercher, J.R.

1994-06-01

340

USING STRUCTURAL EQUATION MODELING TO INVESTIGATE RELATIONSHIPS AMONG ECOLOGICAL VARIABLES  

EPA Science Inventory

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

341

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

342

Twitter's tweet method modelling and simulation  

NASA Astrophysics Data System (ADS)

This paper seeks to purpose the concept of Twitter marketing methods. The tools that Twitter provides are modelled and simulated using iThink in the context of a Twitter media-marketing agency. The paper has leveraged the system's dynamic paradigm to conduct Facebook marketing tools and methods modelling, using iThink™ system to implement them. It uses the design science research methodology for the proof of concept of the models and modelling processes. The following models have been developed for a twitter marketing agent/company and tested in real circumstances and with real numbers. These models were finalized through a number of revisions and iterators of the design, develop, simulate, test and evaluate. It also addresses these methods that suit most organized promotion through targeting, to the Twitter social media service. The validity and usefulness of these Twitter marketing methods models for the day-to-day decision making are authenticated by the management of the company organization. It implements system dynamics concepts of Twitter marketing methods modelling and produce models of various Twitter marketing situations. The Tweet method that Twitter provides can be adjusted, depending on the situation, in order to maximize the profit of the company/agent.

Sarlis, Apostolos S.; Sakas, Damianos P.; Vlachos, D. S.

2015-02-01

343

Advances in NLTE modeling for integrated simulations  

NASA Astrophysics Data System (ADS)

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

Scott, H. A.; Hansen, S. B.

2010-01-01

344

Conceptual ecological models to support detection of ecological change on Alaska National Wildlife Refuges  

USGS Publications Warehouse

More than 31 million hectares of land are protected and managed in 16 refuges by the U.S. Fish and Wildlife Service (USFWS) in Alaska. The vastness and isolation of Alaskan refuges give rise to relatively intact and complete ecosystems. The potential for these lands to provide habitat for trust species is likely to be altered, however, due to global climate change, which is having dramatic effects at high latitudes. The ability of USFWS to effectively manage these lands in the future will be enhanced by a regional inventory and monitoring program that integrates and supplements monitoring currently being implemented by individual refuges. Conceptual models inform monitoring programs in a number of ways, including summarizing important ecosystem components and processes as well as facilitating communication, discussion and debate about the nature of the system and important management issues. This process can lead to hypotheses regarding future changes, likely results of alternative management actions, identification of monitoring indicators, and ultimately, interpretation of monitoring results. As a first step towards developing a monitoring program, the 16 refuges in Alaska each created a conceptual model of their refuge and the landscape context. Models include prominent ecosystem components, drivers, and processes by which components are linked or altered. The Alaska refuge system also recognizes that designing and implementing monitoring at regional and ecoregional extents has numerous scientific, fiscal, logistical, and political advantages over monitoring conducted exclusively at refuge-specific scales. Broad-scale monitoring is particularly advantageous for examining phenomena such as climate change because effects are best interpreted at broader spatial extents. To enable an ecoregional perspective, a rationale was developed for deriving ecoregional boundaries for four ecoregions (Polar, Interior Alaska, Bering Coast, and North Pacific Coast) from the Unified Ecoregions of Alaska. Ecoregional models were then developed to illustrate resources and processes that operate at spatial scales larger than individual refuges within each ecoregion. Conceptual models also were developed for adjacent marine areas, designated as the North Pacific, Bering Sea, and Beaufort-Chukchi Sea Marine Ecoregions. Although many more conceptual models will be required to support development of a regional monitoring program, these definitions of ecoregions and associated conceptual models are an important foundation.

Woodward, Andrea; Beever, Erik A.

2011-01-01

345

Ecological Modelling 117 (1999) 261267 Modeling bird mortality associated with the M/V Citrus oil spill  

E-print Network

Ecological Modelling 117 (1999) 261­267 Modeling bird mortality associated with the M/V Citrus oil/V Citrus oil spill in February 1996. Most of the islands beaches were searched on an irregular schedule estimated number of birds impacted by the M/V Citrus spill 1930. Given that oiled birds occurred in places

Rockwell, Robert F.

346

Modeling and simulation of magnetic nanoparticle sensor.  

PubMed

Sensitivity and detection limit of a magnetic nanoparticle sensor is modeled and simulated. A micro coil generates an alternating magnetic field which excites magnetic nanoparticles in its vicinity. A concentric sensing coil applies Faraday's law of induction measuring the excited magnetization of the magnetic particles at high frequency. A differential measurement compensates disturbances and the influence of the driving microcoil leaving only the signal caused by the magnetic particles. The sensing system can be used for detection of magnetic nanoparticle labels in immunological point of care diagnostics. The paper shows simulation results for a microcoil system capable of detecting a single superparamagnetic nanoparticle. PMID:17282422

Makiranta, Jarkko; Lekkala, Jukka

2005-01-01

347

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

348

Simulated surface tensions of common water models  

NASA Astrophysics Data System (ADS)

Initial simulated values of the surface tension for the SPC/E water model have indicated excellent agreement with experiment. More recently, differing values have been obtained which are significantly lower than previous estimates. Here, we attempt to explain the differences between the previous studies and show that a variety of simulation conditions can affect the final surface tension values. Consistent values for the surface tensions of six common fixed charge water models (TIP3P, SPC, SPC/E, TIP4P, TIP5P, and TIP6P) are then determined for four temperatures between 275 and 350K. The SPC/E and TIP6P models provide the best agreement with experiment.

Chen, Feng; Smith, Paul E.

2007-06-01

349

Simulated surface tensions of common water models.  

PubMed

Initial simulated values of the surface tension for the SPC/E water model have indicated excellent agreement with experiment. More recently, differing values have been obtained which are significantly lower than previous estimates. Here, we attempt to explain the differences between the previous studies and show that a variety of simulation conditions can affect the final surface tension values. Consistent values for the surface tensions of six common fixed charge water models (TIP3P, SPC, SPC/E, TIP4P, TIP5P, and TIP6P) are then determined for four temperatures between 275 and 350 K. The SPC/E and TIP6P models provide the best agreement with experiment. PMID:17581036

Chen, Feng; Smith, Paul E

2007-06-14

350

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

351

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

352

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

353

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

PubMed Central

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

Moustakas, Aristides; Evans, Matthew R.

2013-01-01

354

Electron precipitation models in global magnetosphere simulations  

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

355

Ecological responses to simulated agricultural runoff in a riverine backwater wetland  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

356

DEVELOPMENT AND APPLICATION OF POPULATION MODELS TO SUPPORT EPA'S ECOLOGICAL RISK ASSESSMENT PROCESSES FOR PESTICIDES  

EPA Science Inventory

As part of a broader exploratory effort to develop ecological risk assessment approaches to estimate potential chemical effects on non-target populations, we describe an approach for developing simple population models to estimate the extent to which acute effects on individual...

357

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

E-print Network

Organizational Model for Cooperative and Sustaining Robotic Ecologies Eric Matson Scott DeLoach Multi-Agent and Cooperative Robotics Laboratory Department of Computing and Information Sciences Kansas, and work as a cooperative team to satisfy mission critical goals. The ability for a robotic colony

Deloach, Scott A.

358

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

359

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...

360

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

361

Ecological Engineering 20 (2003) 379387 Engineering role models: do non-human  

E-print Network

for food and survival. Similarly, `keystone species' have greater impacts on community or ecosystem reserved. Keywords: Ecosystem engineers; Biomimicry; Ecosystem function; Keystone species; Exotic speciesEcological Engineering 20 (2003) 379­387 Engineering role models: do non-human species have

Rosemond, Amy Daum

362

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...

363

The Primate Community of Cachoeira (Brazilian Amazonia): A Model to Decipher Ecological Partitioning  

E-print Network

The Primate Community of Cachoeira (Brazilian Amazonia): A Model to Decipher Ecological, Villeurbanne, France Abstract Dental microwear analysis is conducted on a community of platyrrhine primates from South America. This analysis focuses on the primate community of Cachoeira Porteira (Para, Brazil

Paris-Sud XI, Université de

364

Ecological Modelling 185 (2005) 513529 Air quality prediction in Milan: feed-forward neural networks,  

E-print Network

December 2004; accepted 3 January 2005 Abstract Ozone and PM10 constitute the major concern for air qualityEcological Modelling 185 (2005) 513­529 Air quality prediction in Milan: feed-forward neural as state-of-the-art approach for statistical prediction of air quality, are compared with two alternative

Corani, Giorgio

365

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

366

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

ERIC Educational Resources Information Center

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

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

2012-01-01

367

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

368

Applications of next generation sequencing in molecular ecology of non-model organisms  

Microsoft Academic Search

As most biologists are probably aware, technological advances in molecular biology during the last few years have opened up possibilities to rapidly generate large-scale sequencing data from non-model organisms at a reasonable cost. In an era when virtually any study organism can ‘go genomic’, it is worthwhile to review how this may impact molecular ecology. The first studies to put

R Ekblom; J Galindo

2011-01-01

369

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

Microsoft Academic Search

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

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

2010-01-01

370

Testing an ecological model for transmission of Salmonella enterica in swine production ecosystems using genotyping data  

Microsoft Academic Search

An ecological model for transmission of Salmonella enterica in swine production ecosystems was developed, identifying host species, environmental reservoirs, and temporal, spatial, and functional (i.e., stage of production) dimensions. It was hypothesized that transmission was most likely within spatial and functional compartments, between hosts of the same species and abiotic compartments of the same type. Eighteen swine production systems in

Ronald M. Weigel; Daniele Nucera; Baozhen Qiao; Belete Teferedegne; Dong Kyun Suh; David A. Barber; Peter B. Bahnson; Richard E. Isaacson; Bryan A. White

2007-01-01

371

SPATIAL FOREST SOIL PROPERTIES FOR ECOLOGICAL MODELING IN THE WESTERN OREGON CASCADES  

EPA Science Inventory

The ultimate objective of this work is to provide a spatially distributed database of soil properties to serve as inputs to model ecological processes in western forests at the landscape scale. The Central Western Oregon Cascades are rich in biodiversity and they are a fascinati...

372

Models for simulating the fossil record  

NASA Astrophysics Data System (ADS)

Computer modeling of the distribution of fossils within depositional sequences provides a means for generating hypotheses and increasing understanding of the fossil record. The simulation presented here joins the basin-scale stratigraphic modeling program STRATA, a random-branching model of species origination and extinction, and a model relating the probability of species occurrence to sedimentary facies. Model results indicate that facies sensitivity of species has the strongest control on range offset, i.e., the time between last appearance in a stratigraphic column and the time of extinction within a basin or the time between first appearance in a column and time of origination in a basin. Model results also predict the distribution of zones of increased range offset within depositional sequences. In the results presented here, increased range offset occurs within the transgressive systems tract of the deep basin, in far updip settings, and near the shelf break of the late highstand to early lowstand. The model also demonstrates how incompleteness of the fossil record is partitioned among sampling bias, facies bias, and unconformity bias. In this simulation, sampling bias and facies bias are roughly equal in magnitude and constant across the basin, but unconformity bias increasingly dominates over these two in updip positions.

Holland, Steven M.; Patzkowsky, Mark E.

1999-06-01

373

MODEL UNITED NATIONS Model UN conferences are simulations of  

E-print Network

, and crises faced by, the United Nations. Students play the role of diplomats representing the various memberMODEL UNITED NATIONS BACKGROUND Model UN conferences are simulations of the various committees of states of the UN, while negotiating and debating solutions to pressing global issues ranging from

Graham, Nick

374

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

375

Islands as model systems in ecology and evolution: prospects fifty years after MacArthur-Wilson.  

PubMed

The study of islands as model systems has played an important role in the development of evolutionary and ecological theory. The 50th anniversary of MacArthur and Wilson's (December 1963) article, 'An equilibrium theory of insular zoogeography', was a recent milestone for this theme. Since 1963, island systems have provided new insights into the formation of ecological communities. Here, building on such developments, we highlight prospects for research on islands to improve our understanding of the ecology and evolution of communities in general. Throughout, we emphasise how attributes of islands combine to provide unusual research opportunities, the implications of which stretch far beyond islands. Molecular tools and increasing data acquisition now permit re-assessment of some fundamental issues that interested MacArthur and Wilson. These include the formation of ecological networks, species abundance distributions, and the contribution of evolution to community assembly. We also extend our prospects to other fields of ecology and evolution - understanding ecosystem functioning, speciation and diversification - frequently employing assets of oceanic islands in inferring the geographic area within which evolution has occurred, and potential barriers to gene flow. Although island-based theory is continually being enriched, incorporating non-equilibrium dynamics is identified as a major challenge for the future. PMID:25560682

Warren, Ben H; Simberloff, Daniel; Ricklefs, Robert E; Aguilée, Robin; Condamine, Fabien L; Gravel, Dominique; Morlon, Hélène; Mouquet, Nicolas; Rosindell, James; Casquet, Juliane; Conti, Elena; Cornuault, Josselin; Fernández-Palacios, José María; Hengl, Tomislav; Norder, Sietze J; Rijsdijk, Kenneth F; Sanmartín, Isabel; Strasberg, Dominique; Triantis, Kostas A; Valente, Luis M; Whittaker, Robert J; Gillespie, Rosemary G; Emerson, Brent C; Thébaud, Christophe

2015-02-01

376

A superbubble feedback model for galaxy simulations  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

377

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

378

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

379

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

380

The spatial optimism model research for the regional land use based on the ecological constraint  

NASA Astrophysics Data System (ADS)

The study focuses on the Yunnan-Guizhou (i.e. Yunnan province and Guizhou province) Plateau in China. Since the Yunnan-Guizhou region consists of closed basins, the land resources suiting for development are in a shortage, and the ecological problems in the area are quite complicated. In such circumstance, in order to get the applicable basins area and distribution, certain spatial optimism model is needed. In this research, Digital Elevation Model (DEM) and land use data are used to get the boundary rules of the basins distribution. Furthermore, natural risks, ecological risks and human-made ecological risks are integrated to be analyzed. Finally, the spatial overlay analysis method is used to model the developable basins area and distribution for industries and urbanization. The study process can be divided into six steps. First, basins and their distribution need to be recognized. In this way, the DEM data is used to extract the geomorphology characteristics. The plaque regions with gradient under eight degrees are selected. Among these regions, the total area of the plaque with the area above 8 km2 is 54,000 km2, 10% of the total area. These regions are selected to the potential application of industries and urbanization. In the later five steps, analyses are aimed at these regions. Secondly, the natural risks are analyzed. The conditions of the earthquake, debris flow and rainstorm and flood are combined to classify the natural risks. Thirdly, the ecological risks are analyzed containing the ecological sensibility and ecosystem service function importance. According to the regional ecologic features, the sensibility containing the soil erosion, acid rain, stony desertification and survive condition factors is derived and classified according to the medium value to get the ecological sensibility partition. The ecosystem service function importance is classified and divided considering the biology variation protection and water conservation factors. The fourth step is the man-made ecological risks analysis. The mineral resources exploitation, forest resources developing, farming, tourism, industrialization and urbanization are integrated to derive the potential ecological risks made by human activities. The risks weight are given using the expert marking method, Then the man-made ecological risks are classified and divided among the regions. In the fifth step, the comprehensive ecological controlling divisions are obtained based on the above factors classification. At last, the applicable regions and distribution are derived using the spatial overlay analysis removing the higher ecological risks area and considering the land use status. In conclusion, based on the above comprehensive analyses, the applicable basins area are 2,575 km2 and 1,011 km2 respectively for the Yunnan province and Guizhou province. The amount is less than 1% of the perspective province total area focusing on the central part of the two provinces.

XU, K.; Lu, J.; Chi, Y.

2013-12-01

381

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

382

Teaching with Data, Simulations and Models  

NSDL National Science Digital Library

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

383

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...

384

Web-based simulation: web-based modeling and simulation  

Microsoft Academic Search

This paper introduces the emerging area of web-based simulations and presents an overview of the opportunities and challenges in this field. This introduction begins with an outline of the World Wide Web and aspects of simulation impacted by advances on the Internet. Next, various types of applications of web-based simulations are illustrated. This article concludes with an synopsis of research

S. Narayanan

2000-01-01

385

Computer Models Simulate Fine Particle Dispersion  

NASA Technical Reports Server (NTRS)

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

2010-01-01

386

Simulated lights for an airfield model  

NASA Technical Reports Server (NTRS)

A light at an aircraft landing site is simulated on a model board by the protruding output end of a precision cut optical fiber. The fiber is secured within a counterbore of a counterbored hole in the model board. The length of the precision cut fiber and the depth of the counterbore are closely controlled to ensure that the output end of the fiber protrudes a desired distance. The input end of the precision cut fiber is optically coupled to a collimated light source by a second optical fiber extending through the smaller diameter bore of the counterbored hole.

Gdovin, David P. (Inventor); Lusk, Frank J. (Inventor)

1982-01-01

387

Soybean and wheat double cropping simulation model  

SciTech Connect

A computer simulation model of the soybean (Glycine max (L.)Merr.) and wheat (Triticum aestivum L.) double cropping system was developed to analyze the effects on economic return of planting and harvesting rates, planting dates, and proportion of total farm area involved in double cropping. The model considers delays in planting and harvesting due to rainfall. The costs of the various operations are included along with the value of the crops produced. The results of the variation in percentage of area involved in double cropping and size and number of field equipment are shown using 15 years of historical weather data for the Southeast.

Chen, L.H.; McClendon, R.W.

1985-01-01

388

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

NASA Technical Reports Server (NTRS)

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

Pace, Dale K.

2000-01-01

389

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

390

Ecological Models of Sexual Satisfaction among Lesbian\\/Bisexual and Heterosexual Women  

Microsoft Academic Search

Sexual satisfaction is an integral component of sexual health and well-being, yet we know little about which factors contribute\\u000a to it among lesbian\\/bisexual women. To examine a proposed ecological model of sexual satisfaction, we conducted an internet\\u000a survey of married heterosexual women and lesbian\\/bisexual women in committed same-sex relationships. Structural equation modeling\\u000a included five final latent variables for heterosexual women

Alison W. Henderson; Keren Lehavot; Jane M. Simoni

2009-01-01

391

Population Ecology Based and Benefit Oriented Decision-making Model of Project Portfolio Scale  

Microsoft Academic Search

Firstly, by raising the question of decision-making of project portfolio scale, the attribute of population ecology to project portfolio is unveiled. Then, inspired by theories of population competition and interdependence, the project portfolio is classified into two types. Based on these two types, the TPPSD (transverse project portfolio scale decision-making) model and LPPSD (lengthways project portfolio scale decision-making) model are

Guo Peng; Cao Zhao-xi; Zhu Yu-ming; An Hui-gang

2006-01-01

392

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

PubMed

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

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

2012-06-01

393

Supply chain simulation modeling made easy: An innovative approach  

Microsoft Academic Search

Simulation modeling and analysis requires skills and scientific background to be implemented. This is vital for this powerful methodology to deliver value to the company adopting it. There are several practices to implement and rely on simulation modeling for strategic and operational decision making, including hiring simulation engineers, building internal simulation team, or contract consultants. These practices are different in

Dayana Cope; Mohamed Sam Fayez; Mansooreh Mollaghasemi; Assem Kaylani

2007-01-01

394

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

395

Ecological study of river Suswa: modeling DO and BOD.  

PubMed

In this paper limnological status of river Suswa was observed for a period of two years. A water quality Beck modified Khanna Bhutiani model (BMKB model) was developed to calculate DO (dissolved Oxygen) and BOD (biochemical oxygen demand). The model was developed to calculate DO and BOD by using DO/BOD of same place and upstream in previous season which results in Single output. This model gives the seasonal value on the basis of previously taken upstream and downstream observations/concentrations of DO and BOD. The model was calibrated and verified for the water quality data (Physico-chemical data) of samples collected from river Suswa in different seasons. The model gave good agreement between data observed by it and the data observed manually, thus substantiating the validity of the model. Only minor differences were observed in physical, chemical and heavy metals of all the four sampling stations during the course of study. PMID:17058010

Bhutiani, Rakesh; Khanna, D R

2007-02-01

396

Atomistic modeling and simulation of nanopolycrystalline solids  

NASA Astrophysics Data System (ADS)

In the past decades, nanostructured materials have opened new and fascinating avenues for research. Nanopolycrystalline solids, which consist of nano-sized crystalline grains and significant volume fractions of amorphous grain boundaries, are believed to have substantially different response to the thermal-mechanical-electric-magnetic loads, as compared to the response of single-crystalline materials. Nanopolycrystalline materials are expected to play a key role in the next generation of smart materials. This research presents a framework (1) to generate full atomistic models, (2) to perform non-equilibrium molecular dynamics simulations, and (3) to study multi-physics phenomena of nanopolycrystalline solids. This work starts the physical model and mathematical representation with the framework of molecular dynamics. In addition to the latest theories and techniques of molecular dynamics simulations, this work implemented principle of objectivity and incorporates multi-physics features. Further, a database of empirical interatomic potentials is established and the combination scheme for potentials is revisited, which enables investigation of a broad spectrum of chemical elements (as in periodic table) and compounds (such as rocksalt, perovskite, wurtzite, diamond, etc.). The configurational model of nanopolycrystalline solids consists of two spatial components: (1) crystalline grains, which can be obtained through crystal structure optimization, and (2) amorphous grain boundaries, which can be obtained through amorphization process. Therefore, multi-grain multi-phase nanopolycrystalline material system can be constructed by partitioning the space for grains, followed by filling the inter-grain space with amorphous grain boundaries. Computational simulations are performed on several representative crystalline materials and their mixture, such as rocksalt, perovskite and diamond. Problems of relaxation, mechanical loading, thermal stability, heat conduction, electrical field response, magnetic field response are studied. The simulation results of the mechanical, thermal, electrical and magnetic properties are expected to facilitate the rational design and application of nanostructured materials.

Yang, Zidong

397

The impacts of multiple stressors to model ecological structures  

SciTech Connect

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

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

1995-12-31

398

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

399

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

400

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

401

Einfhrung Modell Simulation Vergleich ZF Elektronengleichgewichte von Atomclustern  

E-print Network

Einführung Modell Simulation Vergleich ZF Elektronengleichgewichte von Atomclustern in starken Laserfeldern Diplomarbeit von Bernd Stahl Institut für Theoretische Physik A, RWTH Aachen Institutsseminar 28.06.2006 Bernd Stahl Elektronengleichgewichte von Atomclustern #12;Einführung Modell Simulation Vergleich ZF

Kull, Hans-Jörg

402

Turbulent convection: comparison of Reynolds stress models with numerical simulations  

E-print Network

Turbulent convection: comparison of Reynolds stress models with numerical simulations Friedrich, University of Vienna, A­1090 Vienna, Austria ABSTRACT Numerical simulations of turbulent convection have of basic properties of compressible convection, and stellar atmospheres. Fully nonlocal convection models

Demoulin, Pascal

403

A numerical model simulation of longshore transport for Galveston Island  

E-print Network

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

Gilbreath, Stephen Alexander

1995-01-01

404

Extreme Value Mixture Modelling: evmix Package and Simulation Study  

E-print Network

Extreme Value Mixture Modelling: evmix Package and Simulation Study 8th Conference on Extreme Value Introduction to Extreme Value Mixture Models Generalised Framework New evmix package on CRAN Simulation Study

Scarrott, Carl

405

Simulation of models and algorithms for wireless communication systems  

E-print Network

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

Jabbour, Imad W

2007-01-01

406

Systematic simulations of modified gravity: chameleon models  

SciTech Connect

In this work we systematically study the linear and nonlinear structure formation in chameleon theories of modified gravity, using a generic parameterisation which describes a large class of models using only 4 parameters. For this we have modified the N-body simulation code ecosmog to perform a total of 65 simulations for different models and parameter values, including the default ?CDM. These simulations enable us to explore a significant portion of the parameter space. We have studied the effects of modified gravity on the matter power spectrum and mass function, and found a rich and interesting phenomenology where the difference with the ?CDM paradigm cannot be reproduced by a linear analysis even on scales as large as k ? 0.05 hMpc{sup ?1}, since the latter incorrectly assumes that the modification of gravity depends only on the background matter density. Our results show that the chameleon screening mechanism is significantly more efficient than other mechanisms such as the dilaton and symmetron, especially in high-density regions and at early times, and can serve as a guidance to determine the parts of the chameleon parameter space which are cosmologically interesting and thus merit further studies in the future.

Brax, Philippe [Institut de Physique Theorique, CEA, IPhT, CNRS, URA 2306, F-91191Gif/Yvette Cedex (France); Davis, Anne-Christine [DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Li, Baojiu [Institute for Computational Cosmology, Department of Physics, Durham University, Durham DH1 3LE (United Kingdom); Winther, Hans A. [Institute of Theoretical Astrophysics, University of Oslo, 0315 Oslo (Norway); Zhao, Gong-Bo, E-mail: philippe.brax@cea.fr, E-mail: a.c.davis@damtp.cam.ac.uk, E-mail: baojiu.li@durham.ac.uk, E-mail: h.a.winther@astro.uio.no, E-mail: gong-bo.zhao@port.ac.uk [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX (United Kingdom)

2013-04-01

407

Best Practices for Crash Modeling and Simulation  

NASA Technical Reports Server (NTRS)

Aviation safety can be greatly enhanced by the expeditious use of computer simulations of crash impact. Unlike automotive impact testing, which is now routine, experimental crash tests of even small aircraft are expensive and complex due to the high cost of the aircraft and the myriad of crash impact conditions that must be considered. Ultimately, the goal is to utilize full-scale crash simulations of aircraft for design evaluation and certification. The objective of this publication is to describe "best practices" for modeling aircraft impact using explicit nonlinear dynamic finite element codes such as LS-DYNA, DYNA3D, and MSC.Dytran. Although "best practices" is somewhat relative, it is hoped that the authors' experience will help others to avoid some of the common pitfalls in modeling that are not documented in one single publication. In addition, a discussion of experimental data analysis, digital filtering, and test-analysis correlation is provided. Finally, some examples of aircraft crash simulations are described in several appendices following the main report.

Fasanella, Edwin L.; Jackson, Karen E.

2002-01-01

408

Simulation Assisted Risk Assessment: Blast Overpressure Modeling  

NASA Technical Reports Server (NTRS)

A probabilistic risk assessment (PRA) approach has been developed and applied to the risk analysis of capsule abort during ascent. The PRA is used to assist in the identification of modeling and simulation applications that can significantly impact the understanding of crew risk during this potentially dangerous maneuver. The PRA approach is also being used to identify the appropriate level of fidelity for the modeling of those critical failure modes. The Apollo launch escape system (LES) was chosen as a test problem for application of this approach. Failure modes that have been modeled and/or simulated to date include explosive overpressure-based failure, explosive fragment-based failure, land landing failures (range limits exceeded either near launch or Mode III trajectories ending on the African continent), capsule-booster re-contact during separation, and failure due to plume-induced instability. These failure modes have been investigated using analysis tools in a variety of technical disciplines at various levels of fidelity. The current paper focuses on the development and application of a blast overpressure model for the prediction of structural failure due to overpressure, including the application of high-fidelity analysis to predict near-field and headwinds effects.

Lawrence, Scott L.; Gee, Ken; Mathias, Donovan; Olsen, Michael

2006-01-01

409

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

410

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

411

Using Mechanistic Models to Scale Ecological Processes across Space and Time  

NSDL National Science Digital Library

This peer-reviewed article from BioScience is about using mechanistic models to scale ecological processes. Human activities affect the natural environment at local to global scales. To understand these effects, knowledge derived from short-term studies on small plots needs to be projected to much broader spatial and temporal scales. One way to project short-term, plot-scale knowledge to broader scales is to embed that knowledge in a mechanistic model of the ecosystem. The National Science Foundation's Long Term Ecological Research (LTER) Network makes two vital contributions to this type of modeling effort: (1) a commitment to multidisciplinary research at individual sites, which results in a broad range of mutually consistent data, and (2) long-term data sets essential for estimating rate constants for slow ecosystem processes that dominate long-term ecosystem dynamics. In this article, we present four examples of how a mechanistic approach to modeling ecological processes can be used to make projections to broader scales. The models are all applied to sites in the LTER Network.

EDWARD B. RASTETTER, JOHN D. ABER, DEBRA P. C. PETERS, DENNIS S. OJIMA, and INGRID C. BURKE (; )

2003-01-01

412

Ecological Modelling 165 (2003) 209220 Implications of fetal sex ratio hypotheses in endangered  

E-print Network

Key deer (Odocoileus virginianus clavium). Several general hypotheses have been proposed that describe rights reserved. Keywords: Key deer; Odocoileus virginianus clavium; Fetal sex ratio; Simulation model

Peterson, M. Nils

413

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

414

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.

415

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

USGS Publications Warehouse

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

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

1993-01-01

416

Modeling And Simulation Tools For Education Reform  

NSDL National Science Digital Library

Created by the Shodor Education Foundation, Inc., the Modeling And Simulation Tools for Education Reform (MASTER) provide useful educational tools that help students and teachers learn through observation and modeling activities. The Shodor Foundation worked in tandem with the National Center for Supercomputing Applications, George Mason University, and other educational organizations to craft these tools and visitors can access all eight of them here. The Fractal Modeling Tools are a good place to start as visitors can download the required software or take in some instructional materials, such as the interactive fractal microscope and the snowflake fractal generator. Other notable areas here include The Pit and the Pendulum, which offers the work of Edgar Allan Poe as a way to learn about better reading through computation.

417

Study on Military Equipment Support Modeling and Simulation  

Microsoft Academic Search

In order to estimate the redness, sustainability and support capability of the operational unit, an support simulation concept model of the military equipment is given as viewed from the system engineering modeling and simulation. Simulation test of military aircraft is analyzed in detail, it is composed of the operational mission, function maintenance process and resource modeling.

Wen-jin ZHANG; Rui KANG; Lin-han GUO; Rui-ying LI

2005-01-01

418

DOMAIN DRIVEN SIMULATION MODELING FOR SOFTWARE DESIGN Andrew Evan Ferayorni  

E-print Network

DOMAIN DRIVEN SIMULATION MODELING FOR SOFTWARE DESIGN by Andrew Evan Ferayorni A Thesis Presented 2007 #12;DOMAIN DRIVEN SIMULATION MODELING FOR SOFTWARE DESIGN by Andrew Evan Ferayorni has been for simulating complex systems, but they do not account for domain knowledge. In contrast, Model-Driven Design

419

EDITORIAL: Modelling and simulation in polymer and composites processing  

NASA Astrophysics Data System (ADS)

The general theme of this special section is modelling and simulation in polymer and composite processing. Composite processing in general involves reactive processing. During the last decade there have been numerous advances in modelling and simulation in both thermoplastic and reactive processing. This fact, coupled with the enormous advances in computing capability, has made Computer Aided Engineering (CAE) a reality. Industry nowadays depends on CAE to improve and/or develop new processes. There is no excuse not to take advantage of modelling and simulation. Another tendency is a clear move towards environmentally benign manufacturing; thus several papers in this issue discuss environmentally benign alternatives to traditional manufacturing for both composite and thermoplastics. The first two papers are a review of modelling and simulation; the first paper by Castro, Cabrera Rios and Mount-Campbell focuses on reactive processing, while the second by Kim and Turng discusses thermoplastics moulding. Another important issue is the need to use empirical modelling for cases where physics-based models are not available or are too cumbersome to use. For that reason the paper by Castro et al focuses on empirical modelling and the paper by Kim and Turng discusses exclusively physics-based modelling. The next three papers, two by Advani and collaborators and the third by Srinivasagupta and Kardos, refer to composite manufacturing. Advani's papers cover recent advances in Reactive Liquid Moulding, a process that has gained great acceptance as an environmentally benign alternative to open moulding. The paper by Srinivasagupta and Kardos covers the important issue of addressing simultaneously both environmental and economical design. In general the environmental optimum does not coincide with the economic optimum; this gives rise to the need to compromise. The Data Envelopment Analysis (DEA) technique, discussed in the first paper, can be used to identify the best set of compromises. The exergy approach used by Srinivasagupta and Kardos to evaluate the ecological impact has shown great potential for measuring the effect of processes in the environment. The process they discuss is an environmentally friendly alternative to the standard pultrusion process. The sixth paper, by Chensong Dong and collaborators, focuses on modelling and optimizing dimensional variation in composites, and offers a good complement to Advani's papers. Papers seven by Lilly et al, and eight by Lyytikainen et al, focus on thermoplastic moulding. The last paper, by Chen et al, discusses the modelling of a technology that has the potential to be the environmentally friendly alternative to painting. I would like to thank Dr Mauricio Cabrera Rios, who obtained his PhD under my supervision and is now a professor at the Universidad Autonoma de Nuevo Leon, Mexico, for his help in coordinating the paper reviews. Also, the willingness of the authors to go through several review iterations where needed is greatly appreciated. Finally I would like to thank Ms Judith Adams (editor), without whose help this issue would not have been possible. She was instrumental in securing some papers and in obtaining the proper evaluations of others.

Castro, Josè M.

2004-05-01

420

An individual-based model of a tritrophic ecology  

Microsoft Academic Search

A spatially explicit individual-based model for a predator, prey and plant ecosystem is considered. The movement of the individuals is solely based on nearest-neighbour attraction\\/repulsion and reproduction is asexual. In this simple model emergent spatial organization of the individuals into clusters or groups is present even though all the individuals (predators and prey) are intra-specifically repelled by each other. The

Moshi Arthur Charnell

2008-01-01

421

Modeling galactic chemical evolution in cosmological simulations  

NASA Astrophysics Data System (ADS)

The most fundamental challenges to models of galactic chemical evolution (GCE) are uncertainties in the basic inputs, including the properties of the stellar initial mass function (IMF), stellar nucleosynthetic yields, and the rate of return of mass and energy to the interstellar and intergalactic medium by Type Ia and II supernovae and stellar winds. In this dissertation, we provide a critical examination of widely available stellar nucleosynthetic yield data, with an eye toward modeling GCE in the broad scope of cosmological hydrodynamical simulations. We examine the implications of uncertain inputs for the Galactic stellar IMF, and nucleosynthetic yields from stellar-evolution calculations, on our ability to ask detailed questions regarding the observed Galactic chemical-abundance patterns. We find a marked need for stellar feedback data from stars of initial mass 8 to 12 Msun and above 40 M sun, and for initial stellar metallicities above and below solar, Z sun=0.02. We find the largest discrepancies amongst nucleosynthetic yield calculations are due to various groups' treatment of hot bottom burning, formation of the 13C pocket in asymptotic giant-branch (AGB) stars, and details of mass loss, rotation, and convection in all stars. Our model of GCE is used to post-process simulations to explore in greater detail the nucleosynthetic evolution of the stellar populations and interstellar/intergalactic medium, and to compare directly to the chemical abundances of the Milky Way stellar halo and dwarf spheroidal galaxy stellar populations.

Peruta, Carolyn Cynthia

422

An ecological model of the impact of sexual assault on women's mental health.  

PubMed

This review examines the psychological impact of adult sexual assault through an ecological theoretical perspective to understand how factors at multiple levels of the social ecology contribute to post-assault sequelae. Using Bronfenbrenner's (1979, 1986, 1995) ecological theory of human development, we examine how individual-level factors (e.g., sociodemographics, biological/genetic factors), assault characteristics (e.g., victim-offender relationship, injury, alcohol use), microsystem factors (e.g., informal support from family and friends), meso/ exosystem factors (e.g., contact with the legal, medical, and mental health systems, and rape crisis centers), macrosystem factors (e.g., societal rape myth acceptance), and chronosystem factors (e.g., sexual revictimization and history of other victimizations) affect adult sexual assault survivors' mental health outcomes (e.g., post-traumatic stress disorder, depression, suicidality, and substance use). Self-blame is conceptualized as meta-construct that stems from all levels of this ecological model. Implications for curbing and/or preventing the negative mental health effects of sexual assault are discussed. PMID:19433406

Campbell, Rebecca; Dworkin, Emily; Cabral, Giannina

2009-07-01

423

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

424

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

425

Ecological interpretation of short-term toxicity results: Development of a population model for Arbacia  

SciTech Connect

The Arbacia punctulata fertilization and larval development tests are used extensively in regulatory and research programs to evaluate toxicity associated with contaminants in aqueous media. These short-term assays are inexpensive, easy to use, and provide information regarding the effects of environmental contaminants on critical life history stages of the sea urchin. Despite substantial consideration of the precision of assay methods, and a clear understanding of the statistical significance of treatment differences, an appreciation of the ecological significance of treatment effects is lacking. To address this problem, a stage classified population projection model was developed to relate short-term test endpoints to potential effects at the population level. The model was applied to evaluate population-level effects using short-term toxicity data obtained in an estuarine ecological risk assessment conducted for Portsmouth Naval Shipyard, Kittery, Maine. The model also was used to examine which test endpoints provide useful information relative to population growth dynamics. Population modeling approaches can be extremely valuable in extrapolating single species toxicity information to higher level ecological endpoints and for identifying appropriate measurement endpoints during toxicity test development.

Munns, W.R. Jr.; Nacci, D.E. [SAIC, Narragansett, RI (United States); Walker, H.A. [Environmental Protection Agency, Narragansett, RI (United States); Johnston, R.K. [NCCOSC, Narragansett, RI (United States). RDTE Division

1994-12-31

426

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...

427

A heteroskedastic error covariance matrix estimator using a first-order conditional autoregressive Markov simulation for deriving asympotical efficient estimates from ecological sampled Anopheles arabiensis aquatic habitat covariates  

PubMed Central

Background Autoregressive regression coefficients for Anopheles arabiensis aquatic habitat models are usually assessed using global error techniques and are reported as error covariance matrices. A global statistic, however, will summarize error estimates from multiple habitat locations. This makes it difficult to identify where there are clusters of An. arabiensis aquatic habitats of acceptable prediction. It is therefore useful to conduct some form of spatial error analysis to detect clusters of An. arabiensis aquatic habitats based on uncertainty residuals from individual sampled habitats. In this research, a method of error estimation for spatial simulation models was demonstrated using autocorrelation indices and eigenfunction spatial filters to distinguish among the effects of parameter uncertainty on a stochastic simulation of ecological sampled Anopheles aquatic habitat covariates. A test for diagnostic checking error residuals in an An. arabiensis aquatic habitat model may enable intervention efforts targeting productive habitats clusters, based on larval/pupal productivity, by using the asymptotic distribution of parameter estimates from a residual autocovariance matrix. The models considered in this research extends a normal regression analysis previously considered in the literature. Methods Field and remote-sampled data were collected during July 2006 to December 2007 in Karima rice-village complex in Mwea, Kenya. SAS 9.1.4® was used to explore univariate statistics, correlations, distributions, and to generate global autocorrelation statistics from the ecological sampled datasets. A local autocorrelation index was also generated using spatial covariance parameters (i.e., Moran's Indices) in a SAS/GIS® database. The Moran's statistic was decomposed into orthogonal and uncorrelated synthetic map pattern components using a Poisson model with a gamma-distributed mean (i.e. negative binomial regression). The eigenfunction values from the spatial configuration matrices were then used to define expectations for prior distributions using a Markov chain Monte Carlo (MCMC) algorithm. A set of posterior means were defined in WinBUGS 1.4.3®. After the model had converged, samples from the conditional distributions were used to summarize the posterior distribution of the parameters. Thereafter, a spatial residual trend analyses was used to evaluate variance uncertainty propagation in the model using an autocovariance error matrix. Results By specifying coefficient estimates in a Bayesian framework, the covariate number of tillers was found to be a significant predictor, positively associated with An. arabiensis aquatic habitats. The spatial filter models accounted for approximately 19% redundant locational information in the ecological sampled An. arabiensis aquatic habitat data. In the residual error estimation model there was significant positive autocorrelation (i.e., clustering of habitats in geographic space) based on log-transformed larval/pupal data and the sampled covariate depth of habitat. Conclusion An autocorrelation error covariance matrix and a spatial filter analyses can prioritize mosquito control strategies by providing a computationally attractive and feasible description of variance uncertainty estimates for correctly identifying clusters of prolific An. arabiensis aquatic habitats based on larval/pupal productivity. PMID:19772590

Jacob, Benjamin G; Griffith, Daniel A; Muturi, Ephantus J; Caamano, Erick X; Githure, John I; Novak, Robert J

2009-01-01

428

Toy models for galaxy formation versus simulations  

NASA Astrophysics Data System (ADS)

We describe simple useful toy models for key processes of galaxy formation in its most active phase, at z > 1, and test the approximate expressions against the typical behaviour in a suite of high-resolution hydro-cosmological simulations of massive galaxies at z=4-1. We address in particular the evolution of (a) the total mass inflow rate from the cosmic web into galactic haloes based on the EPS approximation, (b) the penetration of baryonic streams into the inner galaxy, (c) the disc size, (d) the implied steady-state gas content and star formation rate (SFR) in the galaxy subject to mass conservation and a universal star formation law, (e) the inflow rate within the disc to a central bulge and black hole as derived using energy conservation and self-regulated Q ˜ 1 violent disc instability (VDI) and (f) the implied steady state in the disc and bulge. The toy models provide useful approximations for the behaviour of the simulated galaxies. We find that (a) the inflow rate is proportional to mass and to (1 + z)5/2, (b) the penetration to the inner halo is ˜50 per cent at z=4-2, (c) the disc radius is ˜5 per cent of the virial radius, (d) the galaxies reach a steady state with the SFR following the accretion rate into the galaxy, (e) there is an intense gas inflow through the disc, comparable to the SFR, following the predictions of VDI and (f) the galaxies approach a steady state with the bulge mass comparable to the disc mass, where the draining of gas by SFR, outflows and disc inflows is replenished by fresh accretion. Given the agreement with simulations, these toy models are useful for understanding the complex phenomena in simple terms and for back-of-the-envelope predictions.

Dekel, A.; Zolotov, A.; Tweed, D.; Cacciato, M.; Ceverino, D.; Primack, J. R.

2013-10-01

429

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

characterize ecologic differentiation of Triatoma brasiliensis populations, the most important Chagas’ disease vector in northeastern Brazil. The species’ ecologic niche was modeled based on data from the Fundação Nacionalde Saúde of Brazil(1997...

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

2002-11-01

430

Beyond simple linear mixing models: process-based isotope partitioning of ecological processes.  

PubMed

Stable isotopes are valuable tools for partitioning the components contributing to ecological processes of interest, such as animal diets and trophic interactions, plant resource use, ecosystem gas fluxes, streamflow, and many more. Stable isotope data are often analyzed with simple linear mixing (SLM) models to partition the contributions of different sources, but SLM models cannot incorporate a mechanistic understanding of the underlying processes and do not accommodate additional data associated with these processes (e.g., environmental covariates, flux data, gut contents). Thus, SLM models lack predictive ability. We describe a process-based mixing (PBM) model approach for integrating stable isotopes, other data sources, and process models to partition different sources or process components. This is accomplished via a hierarchical Bayesian framework that quantifies multiple sources of uncertainty and enables the incorporation of process models and prior information to help constrain the source-specific proportional contributions, thereby potentially avoiding identifiability issues that plague SLM models applied to "too many" sources. We discuss the application of the PBM model framework to three diverse examples: temporal and spatial partitioning of streamflow, estimation of plant rooting profiles and water uptake profiles (or water sources) with extension to partitioning soil and ecosystem CO2 fluxes, and reconstructing animal diets. These examples illustrate the advantages of the PBM modeling approach, which facilitates incorporation of ecological theory and diverse sources of information into the mixing model framework, thus enabling one to partition key process components across time and space. PMID:24640543

Ogle, Kiona; Tucker, Colin; Cable, Jessica M

2014-01-01

431

Modeling and simulation technology readiness levels.  

SciTech Connect

This report summarizes the results of an effort to establish a framework for assigning and communicating technology readiness levels (TRLs) for the modeling and simulation (ModSim) capabilities at Sandia National Laboratories. This effort was undertaken as a special assignment for the Weapon Simulation and Computing (WSC) program office led by Art Hale, and lasted from January to September 2006. This report summarizes the results, conclusions, and recommendations, and is intended to help guide the program office in their decisions about the future direction of this work. The work was broken out into several distinct phases, starting with establishing the scope and definition of the assignment. These are characterized in a set of key assertions provided in the body of this report. Fundamentally, the assignment involved establishing an intellectual framework for TRL assignments to Sandia's modeling and simulation capabilities, including the development and testing of a process to conduct the assignments. To that end, we proposed a methodology for both assigning and understanding the TRLs, and outlined some of the restrictions that need to be placed on this process and the expected use of the result. One of the first assumptions we overturned was the notion of a ''static'' TRL--rather we concluded that problem context was essential in any TRL assignment, and that leads to dynamic results (i.e., a ModSim tool's readiness level depends on how it is used, and by whom). While we leveraged the classic TRL results from NASA, DoD, and Sandia's NW program, we came up with a substantially revised version of the TRL definitions, maintaining consistency with the classic level definitions and the Predictive Capability Maturity Model (PCMM) approach. In fact, we substantially leveraged the foundation the PCMM team provided, and augmented that as needed. Given the modeling and simulation TRL definitions and our proposed assignment methodology, we conducted four ''field trials'' to examine how this would work in practice. The results varied substantially, but did indicate that establishing the capability dependencies and making the TRL assignments was manageable and not particularly time consuming. The key differences arose in perceptions of how this information might be used, and what value it would have (opinions ranged from negative to positive value). The use cases and field trial results are included in this report. Taken together, the results suggest that we can make reasonably reliable TRL assignments, but that using those without the context of the information that led to those results (i.e., examining the measures suggested by the PCMM table, and extended for ModSim TRL purposes) produces an oversimplified result--that is, you cannot really boil things down to just a scalar value without losing critical information.

Clay, Robert L.; Shneider, Max S.; Marburger, S. J.; Trucano, Timothy Guy

2006-01-01

432

Modelling and simulation of gyrotrons for ITER  

NASA Astrophysics Data System (ADS)

Powerful gyrotrons of the megawatt class will be used for electron cyclotron resonance heating (ECRH) and current drive (ECCD) of magnetically confined plasma in the thermonuclear reactor ITER. For computer-aided design (CAD), analysis and optimization of their performance numerical experiments based on adequate physical models are used. In this paper, we outline and illustrate the current status of both the available software tools for numerical simulation of such gyrotrons, as well as the novel computer codes of the problem oriented GYREOSS software package which is under development now.

Damyanova, M.; Kern, S.; Illy, S.; Thumm, M.; Sabchevski, S.; Zhelyazkov, I.; Vasileva, E.

2014-06-01

433

Petroleum reservoir data for testing simulation models  

SciTech Connect

This report consists of reservoir pressure and production data for 25 petroleum reservoirs. Included are 5 data sets for single-phase (liquid) reservoirs, 1 data set for a single-phase (liquid) reservoir with pressure maintenance, 13 data sets for two-phase (liquid/gas) reservoirs and 6 for two-phase reservoirs with pressure maintenance. Also given are ancillary data for each reservoir that could be of value in the development and validation of simulation models. A bibliography is included that lists the publications from which the data were obtained.

Lloyd, J.M.; Harrison, W.

1980-09-01

434

Why we need more ecology for genetic models such as C. elegans.  

PubMed

Functional information about the large majority of the genes is still lacking in the classical eukaryotic model species Drosophila melanogaster, Caenorhabditis elegans, and Mus musculus. Because many of these genes are likely to be important in natural settings, considering explicit ecological information should increase our knowledge of gene function. Using C. elegans as an example, we discuss the importance of biotic factors as a driving force in shaping the composition and structure of the nematode genome. We highlight examples for which consideration of ecological information and natural variation have been key to the identification of novel, unexpected gene functions, and use these examples to define future research avenues for the classical genetic model taxa. PMID:25577479

Petersen, Carola; Dirksen, Philipp; Schulenburg, Hinrich

2015-03-01

435

Simulation Modelling: Educational Development Roles for Learning Technologists.  

ERIC Educational Resources Information Center

Discusses computer assisted learning and simulation modeling from a United Kingdom perspective. Highlights include modeling with the DMS (Dynamic Modelling System); modeling with STELLA; learning and teaching simulation modeling; educational development roles for learning technologists; and a list of relevant Web sites. (Contains 52 references.)…

Riley, David

2002-01-01

436

Orion Landing Simulation Eight Soil Model Comparison  

NASA Technical Reports Server (NTRS)

LS-DYNA finite element simulations of a rigid Orion Crew Module (CM) were used to investigate the CM impact behavior on eight different soil models. Ten different landing conditions, characterized by the combination of CM vertical and horizontal velocity, hang angle, and roll angle were simulated on the eight different soils. The CM center of gravity accelerations, pitch angle, kinetic energy, and soil contact forces were the outputs of interest. The simulation results are presented, with comparisons of the CM behavior on the different soils. The soils analyzed in this study can be roughly categorized as soft, medium, or hard, according to the CM accelerations that occur when landing on them. The soft group is comprised of the Carson Sink Wet soil and the Kennedy Space Center (KSC) Low Density Dry Sand. The medium group includes Carson Sink Dry, the KSC High Density In-Situ Moisture Sand and High Density Flooded Sand, and Cuddeback B. The hard soils are Cuddeback A and the Gantry Unwashed Sand. The softer soils were found to produce lower peak accelerations, have more stable pitch behavior, and to be less sensitive to the landing conditions. This investigation found that the Cuddeback A soil produced the highest peak accelerations and worst stability conditions, and that the best landing performance was achieved on the KSC Low Density Dry Sand.

Mark, Stephen D.

2009-01-01

437

Modelling non-Euclidean movement and landscape connectivity in highly structured ecological networks  

USGS Publications Warehouse

The ecological distance SCR model uses spatially indexed capture-recapture data to estimate how activity patterns are influenced by landscape structure. As well as reducing bias in estimates of abundance, this approach provides biologically realistic representations of home range geometry, and direct information about species-landscape interactions. The incorporation of both structural (landscape) and functional (movement) components of connectivity provides a direct measure of species-specific landscape connectivity.

Sutherland, Christopher; Fuller, Angela K.; Royle, J. Andrew

2015-01-01

438

Quantitative Estimation Models and Their Application of Ecological Water Use at a Basin Scale  

Microsoft Academic Search

Ecological water use (EWU) is urgent in need in the lower reaches of Tarim River in China. Estimation of water amount for\\u000a EWU is depending on some parameters and modeling. EWU is mainly consists of two parts in no runoff area in the basin, i.e.\\u000a total water amount for restoration groundwater table and total stand water amount of the all

Ranghui Wang; Xinmin Lu

2009-01-01

439

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

440

Ecological Modelling 248 (2013) 3040 Contents lists available at SciVerse ScienceDirect  

E-print Network

of the total carbon mass of a peatland simulated by the Holocene Peat Model (HPM) derived from different sensitivity analysis; HPM, Holocene Peat Model; OAT, one-at-a-time analysis; PFT, plant functional type

Long, Bernard

441

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

442

Developing Mindful Learners Model: A 21st Century Ecological Approach.  

ERIC Educational Resources Information Center

The Developing Mindful Learners Model (DMLM), developed within the framework of Howard Gardner's multiple intelligences theory, connects three factors--content, framework, and world vision--for the purpose of helping underachieving students to become more "mindful": i.e., to become one who welcomes new ideas, considers more than one perspective,…

Fluellen, Jerry

443

Ecological Models and Methods in the Study of School Psychology.  

ERIC Educational Resources Information Center

School psychology is a very complex field further complicated by current socio-political contexts which mandate the development of a psychology of school psychology, requiring two things as first steps. The first step is a model which outlines the conceptual map of the area, gives direction to investigations in the area, and checks on the…

Scott, Myrtle

444

ECOLOGICAL ENDPOINT MODELING: EFFECTS OF SEDIMENT ON FISH POPULATIONS  

EPA Science Inventory

Sediment is one of the main stressors of concern for TMDLs (Total Maximum Daily Loads) for streams, and often it is a concern because of its impact on biological endpoints. The National Research Council (NRC) has recommended that the EPA promote the development of models that ca...

445

Modeling and Simulation Methods for Design of Engineering Systems  

Microsoft Academic Search

This article presents an overview of the state-of-the art in modeling and simulation, and studies to which extent current simulation technologies can effectively support the design process. For simulation-based design, modeling languages and simulation environments must take into account the special characteristics of the design process. For instance, languages should allow models to be easily updated and extended to accommodate

Rajarishi Sinha; Christiaan J. J. Paredis; Vei-chung Liang; Pradeep K. Khosla

2001-01-01

446

VISION: Verifiable Fuel Cycle Simulation Model  

SciTech Connect

The nuclear fuel cycle is a very complex system that includes considerable dynamic complexity as well as detail complexity. In the nuclear power realm, there are experts and considerable research and development in nuclear fuel development, separations technology, reactor physics and waste management. What is lacking is an overall understanding of the entire nuclear fuel cycle and how the deployment of new fuel cycle technologies affects the overall performance of the fuel cycle. The Advanced Fuel Cycle Initiative’s systems analysis group is developing a dynamic simulation model, VISION, to capture the relationships, timing and delays in and among the fuel cycle components to help develop an understanding of how the overall fuel cycle works and can transition as technologies are changed. This paper is an overview of the philosophy and development strategy behind VISION. The paper includes some descriptions of the model and some examples of how to use VISION.

Jacob J. Jacobson; Abdellatif M. Yacout; Gretchen E. Matthern; Steven J. Piet; David E. Shropshire

2009-04-01

447

Modeling and visual simulation of Microalgae photobioreactor  

NASA Astrophysics Data System (ADS)

Microalgae is a kind of nutritious and high photosynthetic efficiency autotrophic plant, which is widely distributed in the land and the sea. It can be extensively used in medicine, food, aerospace, biotechnology, environmental protection and other fields. Photobioreactor which is important equipment is mainly used to cultivate massive and high-density microalgae. In this paper, based on the mathematical model of microalgae which grew under different light intensity, three-dimensional visualization model was built and implemented in 3ds max, Virtools and some other three dimensional software. Microalgae is photosynthetic organism, it can efficiently produce oxygen and absorb carbon dioxide. The goal of the visual simulation is to display its change and impacting on oxygen and carbon dioxide intuitively. In this paper, different temperatures and light intensities were selected to control the photobioreactor, and dynamic change of microalgal biomass, Oxygen and carbon dioxide was observed with the aim of providing visualization support for microalgal and photobioreactor research.

Zhao, Ming; Hou, Dapeng; Hu, Dawei

448

VISION: Verifiable Fuel Cycle Simulation Model  

SciTech Connect

The nuclear fuel cycle consists of a set of complex components that work together in unison. In order to support the nuclear renaissance, it is necessary to understand the impacts of changes and timing of events in any part of the fuel cycle system. The Advanced Fuel Cycle Initiative’s systems analysis group is developing a dynamic simulation model, VISION, to capture the relationships, timing, and changes in and among the fuel cycle components to help develop an understanding of how the overall fuel cycle works. This paper is an overview of the philosophy and development strategy behind VISION. The paper includes some descriptions of the model components and some examples of how to use VISION.

Jacob Jacobson; A. M. Yacout; Gretchen Matthern; Steven Piet; David Shropshire; Tyler Schweitzer

2010-11-01

449

At the Biological Modeling and Simulation Frontier  

PubMed Central

We provide a rationale for and describe examples of synthetic modeling and simulation (M&S) of biological systems. We explain how synthetic methods are distinct from familiar inductive methods. Synthetic M&S is a means to better understand the mechanisms that generate normal and disease-related phenomena observed in research, and how compounds of interest interact with them to alter phenomena. An objective is to build better, working hypotheses of plausible mechanisms. A synthetic model is an extant hypothesis: execution produces an observable mechanism and phenomena. Mobile objects representing compounds carry information enabling components to distinguish between them and react accordingly when different compounds are studied simultaneously. We argue that the familiar inductive approaches contribute to the general inefficiencies being experienced by pharmaceutical R&D, and that use of synthetic approaches accelerates and improves R&D decision-making and thus the drug development process. A reason is that synthetic models encourage and facilitate abductive scientific reasoning, a primary means of knowledge creation and creative cognition. When synthetic models are executed, we observe different aspects of knowledge in action from different perspectives. These models can be tuned to reflect differences in experimental conditions and individuals, making translational research more concrete while moving us closer to personalized medicine. Electronic supplementary material The online version of this article (doi:10.1007/s11095-009-9958-3) contains supplementary material, which is available to authorized users. PMID:19756975

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

2009-01-01

450

Detailed simulation of morphodynamics: 1. Hydrodynamic model  

NASA Astrophysics Data System (ADS)

We present a three-dimensional high-resolution hydrodynamic model for unsteady incompressible flow over an evolving bed topography. This is achieved by using a multilevel Cartesian grid technique that allows the grid to be refined in high-gradient regions and in the vicinity of the river bed. The grid can be locally refined and adapted to the bed geometry, managing the Cartesian grid cells and faces using a hierarchical tree data approach. A ghost-cell immersed-boundary technique is applied to cells intersecting the bed topography. The governing equations have been discretized using a finite-volume method on a staggered grid, conserving second-order accuracy in time and space. The solution advances in time using the fractional step approach. Large-eddy simulation is used as turbulence closure. We validate the model against several experiments and other results from literature. Model results for Stokes flow around a cylinder in the vicinity of a moving wall agree well with Wannier's analytical solution. At higher Reynolds numbers, computed trailing bubble length, separation angle, and drag coefficient compare favorably with experimental and previous computational results. Results for the flow over two- and three-dimensional dunes agree well with published data, including a fair reproduction of recirculation zones, horse-shoe structures, and boiling effects. This shows that the model is suitable for being used as a hydrodynamic submodel in the high-resolution modeling of sediment transport and formation and evolution of subaqueous ripples and dunes.

Nabi, M.; de Vriend, H. J.; Mosselman, E.; Sloff, C. J.; Shimizu, Y.

2012-12-01

451

Modeling human response errors in synthetic flight simulator domain  

NASA Technical Reports Server (NTRS)

This paper presents a control theoretic approach to modeling human response errors (HRE) in the flight simulation domain. The human pilot is modeled as a supervisor of a highly automated system. The synthesis uses the theory of optimal control pilot modeling for integrating the pilot's observation error and the error due to the simulation model (experimental error). Methods for solving the HRE problem are suggested. Experimental verification of the models will be tested in a flight quality handling simulation.

Ntuen, Celestine A.

1992-01-01

452

AI-Based Simulation: An Alternative to Numerical Simulation and Modeling  

E-print Network

AI-Based Simulation: An Alternative to Numerical Simulation and Modeling Shahab D. Mohaghegh1,2 1 technology based on pattern recognition capabilities of artificial intelli- gence and data mining. Keywords Simulation. 1 Introduction In this paper a new class of reservoir models that are developed based on the pat

Mohaghegh, Shahab

453

ecological modelling 2 0 4 ( 2 0 0 7 ) 427438 available at www.sciencedirect.com  

E-print Network

models using artificial neural networks Young-Seuk Parka, , Jorge Rabinovichb , Sovan Lekc a Department of artificial neural networks (ANN) for sensitivity analysis of simulation models, as applied to simulations of the Classification Trees (CT), Sobol and the stepwise multiple regression with standardized partial regression coef

454

Dimensions of Credibility in Models and Simulations  

NASA Technical Reports Server (NTRS)

Based on the National Aeronautics and Space Administration's (NASA's) work in developing a standard for models and simulations (M&S), the subject of credibility in M&S became a distinct focus. This is an indirect result from the Space Shuttle Columbia Accident Investigation Board (CAIB), which eventually resulted in an action, among others, to improve the rigor in NASA's M&S practices. The focus of this action came to mean a standardized method for assessing and reporting results from any type of M&S. As is typical in the standards development process, this necessarily developed into defming a common terminology base, common documentation requirements (especially for M&S used in critical decision making), and a method for assessing the credibility of M&S results. What surfaced in the development of the NASA Standard was the various dimensions credibility to consider when accepting the results from any model or simulation analysis. The eight generally relevant factors of credibility chosen in the NASA Standard proved only one aspect in the dimensionality of M&S credibility. At the next level of detail, the full comprehension of some of the factors requires an understanding along a couple of dimensions as well. Included in this discussion are the prerequisites for the appropriate use of a given M&S, the choice of factors in credibility assessment with their inherent dimensionality, and minimum requirements for fully reporting M&S results.

Steele, Martin J.

2008-01-01

455

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

456

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

457

Global Particle Simulation as A Space Weather Model  

E-print Network

;Outline · Introduction A brief history of global simulations Comparisons among the different methods difficult to transfer physical values at boundaries #12;A brief history of global simulations · 1978: First at the present time, but it will become a vital model · MHD simulations with localized particle simulations very

Nishikawa, Ken-Ichi

458

An ecologically relevant guinea pig model of fetal behavior.  

PubMed

The laboratory guinea pig, Cavia porcellus, shares with humans many similarities during pregnancy and prenatal development, including precocial offspring and social dependence. These similarities suggest the guinea pig as a promising model of fetal behavioral development as well. Using innovative methods of behavioral acclimation, fetal offspring of female IAF hairless guinea pigs time mated to NIH multicolored Hartley males were observed longitudinally without restraint using noninvasive ultrasound at weekly intervals across the 10 week gestation. To ensure that the ultrasound procedure did not cause significant stress, salivary cortisol was collected both before and after each observation. Measures of fetal spontaneous movement and behavioral state were quantified from video recordings from week 3 through the last week before birth. Results from prenatal quantification of Interlimb Movement Synchrony and state organization reveal guinea pig fetal development to be strikingly similar to that previously reported for other rodents and preterm human infants. Salivary cortisol readings taken before and after sonography did not differ at any observation time point. These results suggest this model holds translational promise for studying the prenatal mechanisms of neurobehavioral development, including those that may result from adverse events. Because the guinea pig is a highly social mammal with a wide range of socially oriented vocalizations, this model may also have utility for studying the prenatal origins and trajectories of developmental disabilities with social-emotional components, such as autism. PMID:25655512

Bellinger, S A; Lucas, D; Kleven, G A

2015-04-15

459

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

460

Turning on the Heat: Ecological Response to Simulated Warming in the Sea  

PubMed Central

Significant warming has been observed in every ocean, yet our ability to predict the consequences of oceanic warming on marine biodiversity remains poor. Experiments have been severely limited because, until now, it has not been possible to manipulate seawater temperature in a consistent manner across a range of marine habitats. We constructed a “hot-plate” system to directly examine ecological responses to elevated seawater temperature in a subtidal marine system. The substratum available for colonisation and overlying seawater boundary layer were warmed for 36 days, which resulted in greater biomass of marine organisms and a doubling of space coverage by a dominant colonial ascidian. The “hot-plate” system will facilitate complex manipulations of temperature and multiple stressors in the field to provide valuable information on the response of individuals, populations and communities to environmental change in any aquatic habitat. PMID:21264244

Smale, Dan A.; Wernberg, Thomas; Peck, Lloyd S.; Barnes, David K. A.

2011-01-01