Science.gov

Sample records for ecological simulation modeling

  1. Simulation of socio-ecological impacts: Modeling a fishing village

    NASA Astrophysics Data System (ADS)

    Miller, Philip C.

    1982-03-01

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

  2. Computer simulation model of ecological succession in Australian subtropical rainforest. Environmental Sciences Division Publication No. 1407

    SciTech Connect

    Shugart, H.H.; Mortlock, A.T.; Hopkins, M.S.; Burgess, I.P.

    1980-04-01

    KIAMBRAM, a detailed simulation model for ecological succession in an Australian subtropical humid rainforest is documented in respect to model structure. Model parameters for 125 rainforest tree species are provided. A listing of the KIAMBRAM model and a sample of output from the model is included.

  3. Predicting waste stabilization pond performance using an ecological simulation model

    SciTech Connect

    New, G.R.

    1987-01-01

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

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

    PubMed

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

    2008-05-01

    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

  5. CELSS-3D: a broad computer model simulating a controlled ecological life support system.

    PubMed

    Schneegurt, M A; Sherman, L A

    1997-01-01

    CELSS-3D is a dynamic, deterministic, and discrete computer simulation of a controlled ecological life support system (CELSS) focusing on biological issues. A series of linear difference equations within a graphic-based modeling environment, the IThink program, was used to describe a modular CELSS system. The overall model included submodels for crop growth chambers, food storage reservoirs, the human crew, a cyanobacterial growth chamber, a waste processor, fixed nitrogen reservoirs, and the atmospheric gases, CO, O2, and N2. The primary process variable was carbon, although oxygen and nitrogen flows were also modeled. Most of the input data used in CELSS-3D were from published sources. A separate linear optimization program, What'sBest!, was used to compare options for the crew's vegetarian diet. CELSS-3D simulations were run for the equivalent of 3 years with a 1-h time interval. Output from simulations run under nominal conditions was used to illustrate dynamic changes in the concentrations of atmospheric gases. The modular design of CELSS-3D will allow other configurations and various failure scenarios to be tested and compared. PMID:11540449

  6. 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...

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

    PubMed

    Renaud, Fabrice G; Brown, Colin D

    2008-05-01

    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

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

    NASA Technical Reports Server (NTRS)

    Uschold, Michael

    1992-01-01

    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

  9. A Simulated Stream Ecology Study.

    ERIC Educational Resources Information Center

    Zampella, Robert A.

    1979-01-01

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

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

    PubMed

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

    2012-08-01

    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

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

    PubMed Central

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

    2012-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Pope, A.; Gimblett, R.

    2013-12-01

    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.

  13. Comparison of simulation modeling and satellite techniques for monitoring ecological processes

    NASA Technical Reports Server (NTRS)

    Box, Elgene O.

    1988-01-01

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

  14. The possibility of coexistence and co-development in language competition: ecology-society computational model and simulation.

    PubMed

    Yun, Jian; Shang, Song-Chao; Wei, Xiao-Dan; Liu, Shuang; Li, Zhi-Jie

    2016-01-01

    Language is characterized by both ecological properties and social properties, and competition is the basic form of language evolution. The rise and decline of one language is a result of competition between languages. Moreover, this rise and decline directly influences the diversity of human culture. Mathematics and computer modeling for language competition has been a popular topic in the fields of linguistics, mathematics, computer science, ecology, and other disciplines. Currently, there are several problems in the research on language competition modeling. First, comprehensive mathematical analysis is absent in most studies of language competition models. Next, most language competition models are based on the assumption that one language in the model is stronger than the other. These studies tend to ignore cases where there is a balance of power in the competition. The competition between two well-matched languages is more practical, because it can facilitate the co-development of two languages. A third issue with current studies is that many studies have an evolution result where the weaker language inevitably goes extinct. From the integrated point of view of ecology and sociology, this paper improves the Lotka-Volterra model and basic reaction-diffusion model to propose an "ecology-society" computational model for describing language competition. Furthermore, a strict and comprehensive mathematical analysis was made for the stability of the equilibria. Two languages in competition may be either well-matched or greatly different in strength, which was reflected in the experimental design. The results revealed that language coexistence, and even co-development, are likely to occur during language competition. PMID:27386304

  15. Ecological model of disaster management.

    PubMed

    Beaton, Randal; Bridges, Elizabeth; Salazar, Mary K; Oberle, Mark W; Stergachis, Andy; Thompson, Jack; Butterfield, Patricia

    2008-11-01

    The ecological model of disaster management provides a framework to guide occupational health nurses who are developing disaster management programs.This ecological model assumes that disaster planning, preparedness, response, and recovery occur at various levels of the organization. These nested, increasingly complex organizational levels include individual and family, workplace, community, state, tribal, federal, and global levels. The ecological model hypothesizes that these levels interact and these dynamic interactions determine disaster planning, preparedness, response, and recovery outcomes. In addition to the features of the hazard or disaster, it is also assumed that parallel disaster planning, preparedness, and response elements, logistical challenges, and flexibility, sustainability, and rehabilitation elements occur at each level of the ecological model. Finally, the model assumes that evaluation of response and recovery efforts should inform future planning and preparedness efforts. PMID:19051571

  16. COFLO: A Computer Aid for Teaching Ecological Simulation.

    ERIC Educational Resources Information Center

    Le vow, Roy B.

    A computer-assisted course was designed to provide students with an understanding of modeling and simulation techniques in quantitiative ecology. It deals with continuous systems and has two segments. One develops mathematical and computer tools, beginning with abstract systems and their relation to physical systems. Modeling principles are next…

  17. Ecological reality and model validation

    SciTech Connect

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

    1980-01-01

    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.

  18. Exploring an Ecologically Sustainable Scheme for Landscape Restoration of Abandoned Mine Land: Scenario-Based Simulation Integrated Linear Programming and CLUE-S Model.

    PubMed

    Zhang, Liping; Zhang, Shiwen; Huang, Yajie; Cao, Meng; Huang, Yuanfang; Zhang, Hongyan

    2016-04-01

    Understanding abandoned mine land (AML) changes during land reclamation is crucial for reusing damaged land resources and formulating sound ecological restoration policies. This study combines the linear programming (LP) model and the CLUE-S model to simulate land-use dynamics in the Mentougou District (Beijing, China) from 2007 to 2020 under three reclamation scenarios, that is, the planning scenario based on the general land-use plan in study area (scenario 1), maximal comprehensive benefits (scenario 2), and maximal ecosystem service value (scenario 3). Nine landscape-scale graph metrics were then selected to describe the landscape characteristics. The results show that the coupled model presented can simulate the dynamics of AML effectively and the spatially explicit transformations of AML were different. New cultivated land dominates in scenario 1, while construction land and forest land account for major percentages in scenarios 2 and 3, respectively. Scenario 3 has an advantage in most of the selected indices as the patches combined most closely. To conclude, reclaiming AML by transformation into more forest can reduce the variability and maintain the stability of the landscape ecological system in study area. These findings contribute to better mapping AML dynamics and providing policy support for the management of AML. PMID:27023575

  19. Exploring an Ecologically Sustainable Scheme for Landscape Restoration of Abandoned Mine Land: Scenario-Based Simulation Integrated Linear Programming and CLUE-S Model

    PubMed Central

    Zhang, Liping; Zhang, Shiwen; Huang, Yajie; Cao, Meng; Huang, Yuanfang; Zhang, Hongyan

    2016-01-01

    Understanding abandoned mine land (AML) changes during land reclamation is crucial for reusing damaged land resources and formulating sound ecological restoration policies. This study combines the linear programming (LP) model and the CLUE-S model to simulate land-use dynamics in the Mentougou District (Beijing, China) from 2007 to 2020 under three reclamation scenarios, that is, the planning scenario based on the general land-use plan in study area (scenario 1), maximal comprehensive benefits (scenario 2), and maximal ecosystem service value (scenario 3). Nine landscape-scale graph metrics were then selected to describe the landscape characteristics. The results show that the coupled model presented can simulate the dynamics of AML effectively and the spatially explicit transformations of AML were different. New cultivated land dominates in scenario 1, while construction land and forest land account for major percentages in scenarios 2 and 3, respectively. Scenario 3 has an advantage in most of the selected indices as the patches combined most closely. To conclude, reclaiming AML by transformation into more forest can reduce the variability and maintain the stability of the landscape ecological system in study area. These findings contribute to better mapping AML dynamics and providing policy support for the management of AML. PMID:27023575

  20. Modeling extreme risks in ecology.

    PubMed

    Burgman, Mark; Franklin, James; Hayes, Keith R; Hosack, Geoffrey R; Peters, Gareth W; Sisson, Scott A

    2012-11-01

    Extreme risks in ecology are typified by circumstances in which data are sporadic or unavailable, understanding is poor, and decisions are urgently needed. Expert judgments are pervasive and disagreements among experts are commonplace. We outline approaches to evaluating extreme risks in ecology that rely on stochastic simulation, with a particular focus on methods to evaluate the likelihood of extinction and quasi-extinction of threatened species, and the likelihood of establishment and spread of invasive pests. We evaluate the importance of assumptions in these assessments and the potential of some new approaches to account for these uncertainties, including hierarchical estimation procedures and generalized extreme value distributions. We conclude by examining the treatment of consequences in extreme risk analysis in ecology and how expert judgment may better be harnessed to evaluate extreme risks. PMID:22817845

  1. Long-term impacts of selective logging on two Amazonian tree species with contrasting ecological and reproductive characteristics: inferences from Eco-gene model simulations.

    PubMed

    Vinson, C C; Kanashiro, M; Sebbenn, A M; Williams, T C R; Harris, S A; Boshier, D H

    2015-08-01

    The impact of logging and subsequent recovery after logging is predicted to vary depending on specific life history traits of the logged species. The Eco-gene simulation model was used to evaluate the long-term impacts of selective logging over 300 years on two contrasting Brazilian Amazon tree species, Dipteryx odorata and Jacaranda copaia. D. odorata (Leguminosae), a slow growing climax tree, occurs at very low densities, whereas J. copaia (Bignoniaceae) is a fast growing pioneer tree that occurs at high densities. Microsatellite multilocus genotypes of the pre-logging populations were used as data inputs for the Eco-gene model and post-logging genetic data was used to verify the output from the simulations. Overall, under current Brazilian forest management regulations, there were neither short nor long-term impacts on J. copaia. By contrast, D. odorata cannot be sustainably logged under current regulations, a sustainable scenario was achieved by increasing the minimum cutting diameter at breast height from 50 to 100 cm over 30-year logging cycles. Genetic parameters were only slightly affected by selective logging, with reductions in the numbers of alleles and single genotypes. In the short term, the loss of alleles seen in J. copaia simulations was the same as in real data, whereas fewer alleles were lost in D. odorata simulations than in the field. The different impacts and periods of recovery for each species support the idea that ecological and genetic information are essential at species, ecological guild or reproductive group levels to help derive sustainable management scenarios for tropical forests. PMID:24424164

  2. Long-term impacts of selective logging on two Amazonian tree species with contrasting ecological and reproductive characteristics: inferences from Eco-gene model simulations

    PubMed Central

    Vinson, C C; Kanashiro, M; Sebbenn, A M; Williams, T CR; Harris, S A; Boshier, D H

    2015-01-01

    The impact of logging and subsequent recovery after logging is predicted to vary depending on specific life history traits of the logged species. The Eco-gene simulation model was used to evaluate the long-term impacts of selective logging over 300 years on two contrasting Brazilian Amazon tree species, Dipteryx odorata and Jacaranda copaia. D. odorata (Leguminosae), a slow growing climax tree, occurs at very low densities, whereas J. copaia (Bignoniaceae) is a fast growing pioneer tree that occurs at high densities. Microsatellite multilocus genotypes of the pre-logging populations were used as data inputs for the Eco-gene model and post-logging genetic data was used to verify the output from the simulations. Overall, under current Brazilian forest management regulations, there were neither short nor long-term impacts on J. copaia. By contrast, D. odorata cannot be sustainably logged under current regulations, a sustainable scenario was achieved by increasing the minimum cutting diameter at breast height from 50 to 100 cm over 30-year logging cycles. Genetic parameters were only slightly affected by selective logging, with reductions in the numbers of alleles and single genotypes. In the short term, the loss of alleles seen in J. copaia simulations was the same as in real data, whereas fewer alleles were lost in D. odorata simulations than in the field. The different impacts and periods of recovery for each species support the idea that ecological and genetic information are essential at species, ecological guild or reproductive group levels to help derive sustainable management scenarios for tropical forests. PMID:24424164

  3. Cosmic emergy based ecological systems modelling

    NASA Astrophysics Data System (ADS)

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

    2010-09-01

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

  4. 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...

  5. Simulated coevolution in a mutating ecology

    NASA Astrophysics Data System (ADS)

    Sá Martins, J. S.

    2000-03-01

    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.

  6. Carbon dioxide emissions from Tucuruí reservoir (Amazon biome): New findings based on three-dimensional ecological model simulations.

    PubMed

    Curtarelli, Marcelo Pedroso; Ogashawara, Igor; de Araújo, Carlos Alberto Sampaio; Lorenzzetti, João Antônio; Leão, Joaquim Antônio Dionísio; Alcântara, Enner; Stech, José Luiz

    2016-05-01

    We used a three-dimensional model to assess the dynamics of diffusive carbon dioxide flux (F(CO2)) from a hydroelectric reservoir located at Amazon rainforest. Our results showed that for the studied periods (2013 summer/wet and winter/dry seasons) the surface averaged F(CO2) presented similar behaviors, with regular emissions peaks. The mean daily surface averaged F(CO2) showed no significant difference between the seasons (p>0.01), with values around -1338mg Cm-2day-1 (summer/wet) and -1395mg Cm-2day-1 (winter/dry). At diel scale, the F(CO2) was large during the night and morning and low during the afternoon in both seasons. Regarding its spatial distribution, the F(CO2) showed to be more heterogeneous during the summer/wet than during the winter/dry season. The highest F(CO2) were observed at transition zone (-300mg Cm-2h-1) during summer and at littoral zone (-55mg Cm-2h-1) during the winter. The total CO2 emitted by the reservoir along 2013 year was estimated to be 1.1Tg C year-1. By extrapolating our results we found that the total carbon emitted by all Amazonian reservoirs can be around 7Tg C year-1, which is 22% lower than the previous published estimate. This significant difference should not be neglected in the carbon inventories since the carbon emission is a key factor when comparing the environmental impacts of different sources of electricity generation and can influences decision makers in the selection of the more appropriate source of electricity and, in case of hydroelectricity, the geographical position of the reservoirs. PMID:26914722

  7. 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 ...

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

    SciTech Connect

    S.P. Rupp

    2005-10-01

    In May 2000, the Cerro Grande Fire burned approximately 17,200 ha in north-central New Mexico as the result of an escaped prescribed burn initiated by Bandelier National Monument. The interaction of large-scale fires, vegetation, and elk is an important management issue, but few studies have addressed the ecological implications of vegetative succession and landscape heterogeneity on ungulate populations following large-scale disturbance events. Primary objectives of this research were to identify elk movement pathways on local and landscape scales, to determine environmental factors that influence elk movement, and to evaluate movement and distribution patterns in relation to spatial and temporal aspects of the Cerro Grande Fire. Data collection and assimilation reflect the collaborative efforts of National Park Service, U.S. Forest Service, and Department of Energy (Los Alamos National Laboratory) personnel. Geographic positioning system (GPS) collars were used to track 54 elk over a period of 3+ years and locational data were incorporated into a multi-layered geographic information system (GIS) for analysis. Preliminary tests of GPS collar accuracy indicated a strong effect of 2D fixes on position acquisition rates (PARs) depending on time of day and season of year. Slope, aspect, elevation, and land cover type affected dilution of precision (DOP) values for both 2D and 3D fixes, although significant relationships varied from positive to negative making it difficult to delineate the mechanism behind significant responses. Two-dimensional fixes accounted for 34% of all successfully acquired locations and may affect results in which those data were used. Overall position acquisition rate was 93.3% and mean DOP values were consistently in the range of 4.0 to 6.0 leading to the conclusion collar accuracy was acceptable for modeling purposes. SAVANNA, a spatially explicit, process-oriented ecosystem model, was used to simulate successional dynamics. Inputs to the

  9. WASP TRANSPORT MODELING AND WASP ECOLOGICAL MODELING

    EPA Science Inventory

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

  10. Spatial Uncertainty Analysis of Ecological Models

    SciTech Connect

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

    2000-09-02

    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).

  11. An Interdisciplinary Model for Teaching Evolutionary Ecology.

    ERIC Educational Resources Information Center

    Coletta, John

    1992-01-01

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

  12. The Integration of Ecological processes into a Multi-layer Higher order closure Land Surface Model

    NASA Astrophysics Data System (ADS)

    Chang, K. Y.; Paw U, K. T.; Chen, S. H.

    2015-12-01

    The ecological impacts on biogeophysical and biogeochemical processes were investigated by a series of simulations conducted by a multi-layer higher order closure land surface model (UCD-ACASA) driven by a variety of meteorological and ecological conditions. The results show that the implementation of a more realistic ecological dataset, once carefully quality controlled, can significantly improve the biogeophysical and biogeochemical simulations, which suggests that the ecological impacts on surface layer simulations are as important as the reliability of the selected land surface model. Therefore, the ability to simulate realistic ecological conditions is imperative and beneficial to improve weather and climate simulations. We coupled the ecological processes in UCD-ACASA by adapting the fully prognostic plant carbon and nitrogen dynamics from the version 4.5 of the Community Land Model (CLM4.5). The simulated ecological conditions are sensitive to both radiative transfer processes and leaf distribution inside the canopy, and the multi-layer feature built in UCD-ACASA enables it to describe these properties more realistically as compared to the other big-leaf models. We conducted another set of simulations to examine the reliability of the simulated biogeophysical, biogeochemical and ecological results. The simulated Leaf Area Index (LAI) was compared with a high resolution remotely sensed LAI dataset, and the results show that the simulated LAI tends to overestimate mean LAI and underestimate annual LAI variation at the selected sites. However, the simulated LAI is reasonable enough to produce comparable simulation results against the simulations driven directly by remotely sensed LAI for the tested biogeophysical and biogeochemical fluxes. The results show that ecological impacts on biogeophysical and biogeochemical simulations are significant, and the implementation of biogeochemical processes into a land surface model has the potential to improve weather and

  13. Individual-based models in ecology after four decades

    PubMed Central

    Grimm, Volker

    2014-01-01

    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

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

    SciTech Connect

    Keane, R.E.; Ryan, K.; Running, S.W.

    1995-12-31

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

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

    ERIC Educational Resources Information Center

    Kent, J. W.

    1983-01-01

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

  16. Simulating Ecological Complexity Using the Example of Pesticides in Ecosystems.

    ERIC Educational Resources Information Center

    Muir, Patricia S.; McCune, Bruce

    1993-01-01

    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)

  17. Social Ecological Model Analysis for ICT Integration

    ERIC Educational Resources Information Center

    Zagami, Jason

    2013-01-01

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

  18. Crisis in Context Theory: An Ecological Model

    ERIC Educational Resources Information Center

    Myer, Rick A.; Moore, Holly B.

    2006-01-01

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

  19. Modelling macroevolutionary patterns: An ecological perspective

    NASA Astrophysics Data System (ADS)

    Solé, R. V.

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

  20. 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...

  1. Regional Variation Exaggerates Ecological Divergence in Niche Models

    PubMed Central

    Godsoe, William

    2010-01-01

    Traditionally, the goal of systematics has been to produce classifications that are both strongly supported and biologically meaningful. In recent years several authors have advocated complementing phylogenetic analyses with measures of another form of evolutionary change, ecological divergence. These analyses frequently rely on ecological niche models to determine if species have comparable environmental requirements, but it has heretofore been difficult to test the accuracy of these inferences. To address this problem, I simulate the geographic distributions of allopatric species with identical environmental requirements. I then test whether existing analyses based on geographic distributions will correctly infer that the 2 species' requirements are identical. This work demonstrates that when taxa disperse to different environments, many analyses can erroneously infer changes in environmental requirements, but the severity of the problem depends on the method used. As this could exaggerate the number of ecologically distinct taxa in a clade, I suggest diagnostics to mitigate this problem. PMID:20525637

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

    USGS Publications Warehouse

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

    2014-01-01

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

  3. Agent-based modeling in ecological economics.

    PubMed

    Heckbert, Scott; Baynes, Tim; Reeson, Andrew

    2010-01-01

    Interconnected social and environmental systems are the domain of ecological economics, and models can be used to explore feedbacks and adaptations inherent in these systems. Agent-based modeling (ABM) represents autonomous entities, each with dynamic behavior and heterogeneous characteristics. Agents interact with each other and their environment, resulting in emergent outcomes at the macroscale that can be used to quantitatively analyze complex systems. ABM is contributing to research questions in ecological economics in the areas of natural resource management and land-use change, urban systems modeling, market dynamics, changes in consumer attitudes, innovation, and diffusion of technology and management practices, commons dilemmas and self-governance, and psychological aspects to human decision making and behavior change. Frontiers for ABM research in ecological economics involve advancing the empirical calibration and validation of models through mixed methods, including surveys, interviews, participatory modeling, and, notably, experimental economics to test specific decision-making hypotheses. Linking ABM with other modeling techniques at the level of emergent properties will further advance efforts to understand dynamics of social-environmental systems. PMID:20146761

  4. Simulating ecological changes caused by marine energy devices

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    PubMed

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

    2013-09-01

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

  6. Recent trends in environmental and ecological modelling.

    PubMed

    Jørgensen, S E

    1999-01-01

    The paper outlines the history of modelling and presents a status of ecological modelling: what is the modelling effort of various ecosystem and various environmental problems. Typical validation results and prognosis validation results of a eutrophication model are applied as an illustration of what models can do in environmental management. Structural dynamic modelling which considers parameters that are changed currently by optimisation of a so-called goal function is presented as one of the recent development to overcome one of the most crucial problems in modelling, namely to consider adaptation. Two case studies are presented to illustrate this approach, namely application of biomanipulation and eutrophication of a shallow lake. Forecast on the directions of development is finally presented. PMID:10683676

  7. Modelling ecological systems in a changing world

    PubMed Central

    Evans, Matthew R.

    2012-01-01

    The world is changing at an unprecedented rate. In such a situation, we need to understand the nature of the change and to make predictions about the way in which it might affect systems of interest; often we may also wish to understand what might be done to mitigate the predicted effects. In ecology, we usually make such predictions (or forecasts) by making use of mathematical models that describe the system and projecting them into the future, under changed conditions. Approaches emphasizing the desirability of simple models with analytical tractability and those that use assumed causal relationships derived statistically from data currently dominate ecological modelling. Although such models are excellent at describing the way in which a system has behaved, they are poor at predicting its future state, especially in novel conditions. In order to address questions about the impact of environmental change, and to understand what, if any, action might be taken to ameliorate it, ecologists need to develop the ability to project models into novel, future conditions. This will require the development of models based on understanding the processes that result in a system behaving the way it does, rather than relying on a description of the system, as a whole, remaining valid indefinitely. PMID:22144381

  8. Handbook of Scaling Methods in Aquatic Ecology: Measurement, Analysis, Simulation

    NASA Astrophysics Data System (ADS)

    Marrasé, Celia

    2004-03-01

    Researchers in aquatic sciences have long been interested in describing temporal and biological heterogeneities at different observation scales. During the 1970s, scaling studies received a boost from the application of spectral analysis to ecological sciences. Since then, new insights have evolved in parallel with advances in observation technologies and computing power. In particular, during the last 2 decades, novel theoretical achievements were facilitated by the use of microstructure profilers, the application of mathematical tools derived from fractal and wavelet analyses, and the increase in computing power that allowed more complex simulations. The idea of publishing the Handbook of Scaling Methods in Aquatic Ecology arose out of a special session of the 2001 Aquatic Science Meeting of the American Society of Limnology and Oceanography. The edition of the book is timely, because it compiles a good amount of the work done in these last 2 decades. The book is comprised of three sections: measurements, analysis, and simulation. Each contains some review chapters and a number of more specialized contributions. The contents are multidisciplinary and focus on biological and physical processes and their interactions over a broad range of scales, from micro-layers to ocean basins. The handbook topics include high-resolution observation methodologies, as well as applications of different mathematical tools for analysis and simulation of spatial structures, time variability of physical and biological processes, and individual organism behavior. The scientific background of the authors is highly diverse, ensuring broad interest for the scientific community.

  9. Rainfall simulation experiments in ecological and conventional vineyards.

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  10. Simulating social-ecological systems: the Island Digital Ecosystem Avatars (IDEA) consortium.

    PubMed

    Davies, Neil; Field, Dawn; Gavaghan, David; Holbrook, Sally J; Planes, Serge; Troyer, Matthias; Bonsall, Michael; Claudet, Joachim; Roderick, George; Schmitt, Russell J; Zettler, Linda Amaral; Berteaux, Véronique; Bossin, Hervé C; Cabasse, Charlotte; Collin, Antoine; Deck, John; Dell, Tony; Dunne, Jennifer; Gates, Ruth; Harfoot, Mike; Hench, James L; Hopuare, Marania; Kirch, Patrick; Kotoulas, Georgios; Kosenkov, Alex; Kusenko, Alex; Leichter, James J; Lenihan, Hunter; Magoulas, Antonios; Martinez, Neo; Meyer, Chris; Stoll, Benoit; Swalla, Billie; Tartakovsky, Daniel M; Murphy, Hinano Teavai; Turyshev, Slava; Valdvinos, Fernanda; Williams, Rich; Wood, Spencer

    2016-01-01

    Systems biology promises to revolutionize medicine, yet human wellbeing is also inherently linked to healthy societies and environments (sustainability). The IDEA Consortium is a systems ecology open science initiative to conduct the basic scientific research needed to build use-oriented simulations (avatars) of entire social-ecological systems. Islands are the most scientifically tractable places for these studies and we begin with one of the best known: Moorea, French Polynesia. The Moorea IDEA will be a sustainability simulator modeling links and feedbacks between climate, environment, biodiversity, and human activities across a coupled marine-terrestrial landscape. As a model system, the resulting knowledge and tools will improve our ability to predict human and natural change on Moorea and elsewhere at scales relevant to management/conservation actions. PMID:26998258

  11. Aviation Safety Simulation Model

    NASA Technical Reports Server (NTRS)

    Houser, Scott; Yackovetsky, Robert (Technical Monitor)

    2001-01-01

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

  12. Modeling and simulation

    SciTech Connect

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

    1986-01-01

    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.

  13. Modelling the unpredictability of future biodiversity in ecological networks.

    PubMed

    Ingram, Travis; Steel, Mike

    2010-06-01

    We consider the question of how accurately we can hope to predict future biodiversity in a world in which many interacting species are at risk of extinction. Simple models assuming that species' extinctions occur independently are easily analysed, but do not account for the fact that many species depend on or otherwise interact with each other. In this paper we evaluate the effect of explicitly incorporating ecological dependencies on the predictive ability of models of extinction. In particular, we compare a model in which species' extinction rates increase because of the extinction of their prey to a model in which the same average rate increase takes place, but in which extinctions occur independently from species to species. One might expect that including this ecological information would make the prediction of future biodiversity more accurate, but instead we find that accounting for food web dependencies reveals greater uncertainty. The expected loss of biodiversity over time is similar between the two models, but the variance in future biodiversity is considerably higher in the model that includes species interactions. This increased uncertainty is because of the non-independence of species-the tendency of two species to respond similarly to the loss of a species on which both depend. We use simulations to show that this increase in variance is robust to many variations of the model, and that its magnitude should be largest in food webs that are highly dependent on a few basal species. Our results should hold whenever ecological dependencies cause most species' extinction risks to covary positively, and illustrate how more information does not necessarily improve our ability to predict future biodiversity loss. PMID:20211629

  14. Dynamic simulation of the laboratory-scale controlled ecological life support system.

    PubMed

    Finn, C K; Srinivasan, V

    1995-01-01

    There are a number of design and control issues that need to be resolved in order to make a crop growth chamber an integral part of a controlled ecological life support system (CELSS) capable of supporting life on extended space missions. A modeling and simulation effort, along with the construction of an experimental testbed, are underway at NASA Ames Research Center to explore the long-term dynamic behavior of closed-loop life support systems. One problem that has been isolated for investigation is the stability and robustness of closed-loop systems over extended periods of time. Currently a crop growth chamber is being integrated with a solid waste processor to study closure of the carbon loop. A dynamic simulation model of the system was developed to evaluate system design options and operational alternatives. The model was also used to simulate the impact of system buffer size on the dynamic behavior of conditions inside the crop growth chamber. PMID:11538310

  15. System dynamic modelling of industrial growth and landscape ecology in China.

    PubMed

    Xu, Jian; Kang, Jian; Shao, Long; Zhao, Tianyu

    2015-09-15

    With the rapid development of large industrial corridors in China, the landscape ecology of the country is currently being affected. Therefore, in this study, a system dynamic model with multi-dimensional nonlinear dynamic prediction function that considers industrial growth and landscape ecology is developed and verified to allow for more sustainable development. Firstly, relationships between industrial development and landscape ecology in China are examined, and five subsystems are then established: industry, population, urban economy, environment and landscape ecology. The main influencing factors are then examined for each subsystem to establish flow charts connecting those factors. Consequently, by connecting the subsystems, an overall industry growth and landscape ecology model is established. Using actual data and landscape index calculated based on GIS of the Ha-Da-Qi industrial corridor, a typical industrial corridor in China, over the period 2005-2009, the model is validated in terms of historical behaviour, logical structure and future prediction, where for 84.8% of the factors, the error rate of the model is less than 5%, the mean error rate of all factors is 2.96% and the error of the simulation test for the landscape ecology subsystem is less than 2%. Moreover, a model application has been made to consider the changes in landscape indices under four industrial development modes, and the optimal industrial growth plan has been examined for landscape ecological protection through the simulation prediction results over 2015-2020. PMID:26160664

  16. Computer Modeling and Simulation

    SciTech Connect

    Pronskikh, V. S.

    2014-05-09

    Verification and validation of computer codes and models used in simulation are two aspects of the scientific practice of high importance and have recently been discussed by philosophers of science. While verification is predominantly associated with the correctness of the way a model is represented by a computer code or algorithm, validation more often refers to model’s relation to the real world and its intended use. It has been argued that because complex simulations are generally not transparent to a practitioner, the Duhem problem can arise for verification and validation due to their entanglement; such an entanglement makes it impossible to distinguish whether a coding error or model’s general inadequacy to its target should be blamed in the case of the model failure. I argue that in order to disentangle verification and validation, a clear distinction between computer modeling (construction of mathematical computer models of elementary processes) and simulation (construction of models of composite objects and processes by means of numerical experimenting with them) needs to be made. Holding on to that distinction, I propose to relate verification (based on theoretical strategies such as inferences) to modeling and validation, which shares the common epistemology with experimentation, to simulation. To explain reasons of their intermittent entanglement I propose a weberian ideal-typical model of modeling and simulation as roles in practice. I suggest an approach to alleviate the Duhem problem for verification and validation generally applicable in practice and based on differences in epistemic strategies and scopes

  17. Theory Modeling and Simulation

    SciTech Connect

    Shlachter, Jack

    2012-08-23

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

  18. AN INTRODUCTION TO THE PRACTICE OF ECOLOGICAL MODELING

    EPA Science Inventory

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

  19. Controlled Ecological Life Support System (CELSS) modeling

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    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.

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

    PubMed

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

    2012-01-15

    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

  1. Stochastic Downscaling for Hydrodynamic and Ecological Modeling of Lakes

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  2. 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...

  3. Progress and Challenges in Coupled Hydrodynamic-Ecological Estuarine Modeling

    EPA Science Inventory

    Numerical modeling has emerged over the last several decades as a widely accepted tool for investigations in environmental sciences. In estuarine research, hydrodynamic and ecological models have moved along parallel tracks with regard to complexity, refinement, computational po...

  4. 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...

  5. Cognitive Modeling for Agent-Based Simulation of Child Maltreatment

    NASA Astrophysics Data System (ADS)

    Hu, Xiaolin; Puddy, Richard

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

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

    SciTech Connect

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

    2010-04-10

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

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

    ERIC Educational Resources Information Center

    Lohrmann, David K.

    2010-01-01

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

  8. Documentation of the Ecological Risk Assessment Computer Model ECORSK.5

    SciTech Connect

    Anthony F. Gallegos; Gilbert J. Gonzales

    1999-06-01

    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.

  9. Analytically tractable model for community ecology with many species.

    PubMed

    Dickens, Benjamin; Fisher, Charles K; Mehta, Pankaj

    2016-08-01

    A fundamental problem in community ecology is understanding how ecological processes such as selection, drift, and immigration give rise to observed patterns in species composition and diversity. Here, we analyze a recently introduced, analytically tractable, presence-absence (PA) model for community assembly, and we use it to ask how ecological traits such as the strength of competition, the amount of diversity, and demographic and environmental stochasticity affect species composition in a community. In the PA model, species are treated as stochastic binary variables that can either be present or absent in a community: species can immigrate into the community from a regional species pool and can go extinct due to competition and stochasticity. Building upon previous work, we show that, despite its simplicity, the PA model reproduces the qualitative features of more complicated models of community assembly. In agreement with recent studies of large, competitive Lotka-Volterra systems, the PA model exhibits distinct ecological behaviors organized around a special ("critical") point corresponding to Hubbell's neutral theory of biodiversity. These results suggest that the concepts of ecological "phases" and phase diagrams can provide a powerful framework for thinking about community ecology, and that the PA model captures the essential ecological dynamics of community assembly. PMID:27627348

  10. Boechera, a model system for ecological genomics

    PubMed Central

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

    2011-01-01

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

  11. Boechera, a model system for ecological genomics.

    PubMed

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

    2011-12-01

    The selection and development of a study system for evolutionary and ecological functional genomics (EEFG) depend 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 as follows: (i) native populations in undisturbed habitats where current environments reflect historical conditions over several thousand years; (ii) functional genomics benefitting from its close relationship to Arabidopsis thaliana; (iii) inbreeding tolerance enabling development of recombinant inbred lines, near-isogenic lines and positional cloning; (iv) interspecific crosses permitting mapping for genetic analysis of speciation; (v) apomixis (asexual reproduction by seeds) in a genetically tractable diploid; and (vi) 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

  12. [Simulation of urban ecological security pattern based on cellular automata: a case of Dongguan City, Guangdong Province of South China].

    PubMed

    Yang, Qing-Sheng; Qiao, Ji-Gang; Ai, Bin

    2013-09-01

    Taking the Dongguan City with rapid urbanization as a case, and selecting landscape ecological security level as evaluation criterion, the urbanization cellular number of 1 km x 1 km ecological security cells was obtained, and imbedded into the transition rules of cellular automata (CA) as the restraint term to control urban development, establish ecological security urban CA, and simulate ecological security urban development pattern. The results showed the integrated landscape ecological security index of the City decreased from 0.497 in 1998 to 0.395 in 2005, indicating that the ecological security at landscape scale was decreased. The CA-simulated integrated ecological security index of the City in 2005 was increased from the measured 0.395 to 0.479, showing that the simulated urban landscape ecological pressure from human became lesser, ecological security became better, and integrated landscape ecological security became higher. CA could be used as an effective tool in researching urban ecological security. PMID:24417120

  13. Ecological risk assessment of genetically modified crops based on cellular automata modeling.

    PubMed

    Yang, Jun; Wang, Zhi-Rui; Yang, De-Li; Yang, Qing; Yan, Jun; He, Ming-Feng

    2009-01-01

    The assessment of ecological risk in genetically modified (GM) biological systems is critically important for decision-making and public acceptance. Cellular automata (CA) provide a potential modeling and simulation framework for representing relationships and interspecies interactions both temporally and spatially. In this paper, a simple subsystem contains only four species: crop, target pest, non-target pest and enemy insect, and a three layer arrangement of LxL stochastic cellular automata with a periodic boundary were established. The simulation of this simplified system showed abundant and sufficient complexity in population assembly and densities, suggesting a prospective application in ecological risk assessment of GM crops. PMID:19477260

  14. 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...

  15. An analytically tractable model for community ecology with many species

    NASA Astrophysics Data System (ADS)

    Dickens, Benjamin; Fisher, Charles; Mehta, Pankaj; Pankaj Mehta Biophysics Theory Group Team

    A fundamental problem in community ecology is to understand how ecological processes such as selection, drift, and immigration yield observed patterns in species composition and diversity. Here, we present an analytically tractable, presence-absence (PA) model for community assembly and use it to ask how ecological traits such as the strength of competition, diversity in competition, and stochasticity affect species composition in a community. In our PA model, we treat species as stochastic binary variables that can either be present or absent in a community: species can immigrate into the community from a regional species pool and can go extinct due to competition and stochasticity. Despite its simplicity, the PA model reproduces the qualitative features of more complicated models of community assembly. In agreement with recent work on large, competitive Lotka-Volterra systems, the PA model exhibits distinct ecological behaviors organized around a special (``critical'') point corresponding to Hubbell's neutral theory of biodiversity. Our results suggest that the concepts of ``phases'' and phase diagrams can provide a powerful framework for thinking about community ecology and that the PA model captures the essential ecological dynamics of community assembly. Pm was supported by a Simons Investigator in the Mathematical Modeling of Living Systems and a Sloan Research Fellowship.

  16. Probabilistic ecological risk assessment of effluent toxicity of a wastewater reclamation plant based on process modeling.

    PubMed

    Zeng, Siyu; Huang, Yunqing; Sun, Fu; Li, Dan; He, Miao

    2016-09-01

    The growing use of reclaimed wastewater for environmental purposes such as stream flow augmentation requires comprehensive ecological risk assessment and management. This study applied a system analysis approach, regarding a wastewater reclamation plant (WRP) and its recipient water body as a whole system, and assessed the ecological risk of the recipient water body caused by the WRP effluent. Instead of specific contaminants, two toxicity indicators, i.e. genotoxicity and estrogenicity, were selected to directly measure the biological effects of all bio-available contaminants in the reclaimed wastewater, as well as characterize the ecological risk of the recipient water. A series of physically based models were developed to simulate the toxicity indicators in a WRP through a typical reclamation process, including ultrafiltration, ozonation, and chlorination. After being validated against the field monitoring data from a full-scale WRP in Beijing, the models were applied to simulate the probability distribution of effluent toxicity of the WRP through Latin Hypercube Sampling to account for the variability of influent toxicity and operation conditions. The simulated effluent toxicity was then used to derive the predicted environmental concentration (PEC) in the recipient stream, considering the variations of the toxicity and flow of the upstream inflow as well. The ratio of the PEC of each toxicity indicator to its corresponding predicted no-effect concentration was finally used for the probabilistic ecological risk assessment. Regional sensitivity analysis was also performed with the developed models to identify the critical control variables and strategies for ecological risk management. PMID:27219046

  17. Advances and Limitations of Disease Biogeography Using Ecological Niche Modeling.

    PubMed

    Escobar, Luis E; Craft, Meggan E

    2016-01-01

    Mapping disease transmission risk is crucial in public and animal health for evidence based decision-making. Ecology and epidemiology are highly related disciplines that may contribute to improvements in mapping disease, which can be used to answer health related questions. Ecological niche modeling is increasingly used for understanding the biogeography of diseases in plants, animals, and humans. However, epidemiological applications of niche modeling approaches for disease mapping can fail to generate robust study designs, producing incomplete or incorrect inferences. This manuscript is an overview of the history and conceptual bases behind ecological niche modeling, specifically as applied to epidemiology and public health; it does not pretend to be an exhaustive and detailed description of ecological niche modeling literature and methods. Instead, this review includes selected state-of-the-science approaches and tools, providing a short guide to designing studies incorporating information on the type and quality of the input data (i.e., occurrences and environmental variables), identification and justification of the extent of the study area, and encourages users to explore and test diverse algorithms for more informed conclusions. We provide a friendly introduction to the field of disease biogeography presenting an updated guide for researchers looking to use ecological niche modeling for disease mapping. We anticipate that ecological niche modeling will soon be a critical tool for epidemiologists aiming to map disease transmission risk, forecast disease distribution under climate change scenarios, and identify landscape factors triggering outbreaks. PMID:27547199

  18. Advances and Limitations of Disease Biogeography Using Ecological Niche Modeling

    PubMed Central

    Escobar, Luis E.; Craft, Meggan E.

    2016-01-01

    Mapping disease transmission risk is crucial in public and animal health for evidence based decision-making. Ecology and epidemiology are highly related disciplines that may contribute to improvements in mapping disease, which can be used to answer health related questions. Ecological niche modeling is increasingly used for understanding the biogeography of diseases in plants, animals, and humans. However, epidemiological applications of niche modeling approaches for disease mapping can fail to generate robust study designs, producing incomplete or incorrect inferences. This manuscript is an overview of the history and conceptual bases behind ecological niche modeling, specifically as applied to epidemiology and public health; it does not pretend to be an exhaustive and detailed description of ecological niche modeling literature and methods. Instead, this review includes selected state-of-the-science approaches and tools, providing a short guide to designing studies incorporating information on the type and quality of the input data (i.e., occurrences and environmental variables), identification and justification of the extent of the study area, and encourages users to explore and test diverse algorithms for more informed conclusions. We provide a friendly introduction to the field of disease biogeography presenting an updated guide for researchers looking to use ecological niche modeling for disease mapping. We anticipate that ecological niche modeling will soon be a critical tool for epidemiologists aiming to map disease transmission risk, forecast disease distribution under climate change scenarios, and identify landscape factors triggering outbreaks. PMID:27547199

  19. [Removal of nitrogen in simulated rivers embanked by ecological concrete].

    PubMed

    Chen, Yang-hui; Lü, Xi-wu; Wu, Yi-feng

    2008-08-01

    The removal of nitrogen was studied in four types of pilot-scale rivers. The embankment for rivers No. 1, 2 and 3 consisted of respectively spheriform ecological-concrete prefab-bricks, rectangular ecological-concrete prefab-bricks and square ecological-concrete prefab-bricks with 4 hemispheroids. The embankment for river No. 4 was made of concrete C25. The results show that the removal rates of NH4+ -N, NO2- -N, NO3- -N and TN of river 1 are 83.6%, 75.2%, 37.1% and 47.5% under hydraulic retention time of 2 days, 83.4%, 53.0%, 30.6% and 40.4% for river 2, 88.1%, 72.4%, 33.0% and 40.9% for river 3. Under the same condition, NH4+ -N, TN of river 4 decreasesby 61.1%, 9.1%, while NO2- -N, NO3- -N increase by 7.4%, 3.4% due to the transformation of NH4+ -N. It indicates that ecological embankment rivers can effectively remove nitrogen. Besides, the addition of pore rate in embankment structure and more rate of plant coverage are good for the removal of nitrogen in ecological embankment rivers. PMID:18839568

  20. Gyrokinetic particle simulation model

    SciTech Connect

    Lee, W.W.

    1986-07-01

    A new type of particle simulation model based on the gyrophase-averaged Vlasov and Poisson equations is presented. The reduced system, in which particle gyrations are removed from the equations of motion while the finite Larmor radius effects are still preserved, is most suitable for studying low frequency microinstabilities in magnetized plasmas. It is feasible to simulate an elongated system (L/sub parallel/ >> L/sub perpendicular/) with a three-dimensional grid using the present model without resorting to the usual mode expansion technique, since there is essentially no restriction on the size of ..delta..x/sub parallel/ in a gyrokinetic plasma. The new approach also enables us to further separate the time and spatial scales of the simulation from those associated with global transport through the use of multiple spatial scale expansion. Thus, the model can be a very efficient tool for studying anomalous transport problems related to steady-state drift-wave turbulence in magnetic confinement devices. It can also be applied to other areas of plasma physics.

  1. 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...

  2. 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...

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

    EPA Science Inventory

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

  4. Comparison of Ecological Validity of Learning Disabilities Diagnostic Models

    ERIC Educational Resources Information Center

    Dean, Vincent J.; Burns, Matthew K.; Grialou, Tina; Varro, Patrick J.

    2006-01-01

    The purpose of this article is to examine models designed for the determination of a learning disability and compare them to specific criteria to determine whether the given diagnostic process is ecological in nature. The traditional child-centered deficit model (CCD), Relative Achievement Discrepancy model (RAD), and Responsiveness to…

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

    PubMed

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

    2005-06-01

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

  6. Guide for developing conceptual models for ecological risk assessments

    SciTech Connect

    Suter, G.W., II

    1996-05-01

    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.

  7. Ecology.

    ERIC Educational Resources Information Center

    National Audubon Society, New York, NY.

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

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

    EPA Science Inventory

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

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

    ERIC Educational Resources Information Center

    Li, Weidong; Rukavina, Paul

    2012-01-01

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

  10. Ecological niche modelling of bank voles in Western Europe.

    PubMed

    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

    2013-02-01

    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 (χ(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

  11. Electricity Portfolio Simulation Model

    Energy Science and Technology Software Center (ESTSC)

    2005-09-01

    Stakeholders often have competing interests when selecting or planning new power plants. The purpose of developing this preliminary Electricity Portfolio Simulation Model (EPSim) is to provide a first cut, dynamic methodology and approach to this problem, that can subsequently be refined and validated, that may help energy planners, policy makers, and energy students better understand the tradeoffs associated with competing electricity portfolios. EPSim allows the user to explore competing electricity portfolios annually from 2002 tomore » 2025 in terms of five different criteria: cost, environmental impacts, energy dependence, health and safety, and sustainability. Four additional criteria (infrastructure vulnerability, service limitations, policy needs and science and technology needs) may be added in future versions of the model. Using an analytic hierarchy process (AHP) approach, users or groups of users apply weights to each of the criteria. The default energy assumptions of the model mimic Department of Energy’s (DOE) electricity portfolio to 2025 (EIA, 2005). At any time, the user can compare alternative portfolios to this reference case portfolio.« less

  12. SSPX simulation model

    SciTech Connect

    Fowler, T K

    1999-09-20

    An analytical approximation to an R-L-C circuit representing SSPX is shown to reproduce the observed capacitor bank efficiency and gun optimization data. As in the SPICE code, the spheromak gun is represented by a fixed resistance chosen to balance energy transfer to the gun. A revised estimate of the magnetic decay time in SSPX Shot 1822 then brings our estimate of the gun efficiency itself in line with the observed spheromak magnetic field for this shot. Prompted by these successes, we present a turbulence-based theoretical model for the spheromak resistance that can be implemented in the SPICE code, of the form: R{sub s} = {kappa}I (1-I{sub 0}/I){sup 2} where I is the gun current, I{sub 0} = ({Lambda}{sub 0}/{mu}{sub 0}){Phi} with bias flux and Taylor eigenvalue {lambda}{sub 0}, and {kappa} is a coefficient based on the magnetic turbulence model employed in Dan Hua's spheromak simulation code. The value of {kappa} giving a good energy balance (around 0.1 m{Omega}/KA) implies substantial turbulence levels. Implementing our model in SPICE would provide a calibration for theoretical calculations of the turbulence. Our analytic approximation to the SPICE code provides guidance to optimize future performance in SSPX, the greatest benefit appearing to come from reducing or eliminating the protective resistor to increase bank efficiency. Eliminating the resistor altogether doubles the bank efficiency and the spheromak magnetic energy.

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

    PubMed Central

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

    2014-01-01

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

  14. Individual-based modeling of ecological and evolutionary processes

    USGS Publications Warehouse

    DeAngelis, Donald L.; Mooij, Wolf M.

    2005-01-01

    Individual-based models (IBMs) allow the explicit inclusion of individual variation in greater detail than do classical differential-equation and difference-equation models. Inclusion of such variation is important for continued progress in ecological and evolutionary theory. We provide a conceptual basis for IBMs by describing five major types of individual variation in IBMs: spatial, ontogenetic, phenotypic, cognitive, and genetic. IBMs are now used in almost all subfields of ecology and evolutionary biology. We map those subfields and look more closely at selected key papers on fish recruitment, forest dynamics, sympatric speciation, metapopulation dynamics, maintenance of diversity, and species conservation. Theorists are currently divided on whether IBMs represent only a practical tool for extending classical theory to more complex situations, or whether individual-based theory represents a radically new research program. We feel that the tension between these two poles of thinking can be a source of creativity in ecology and evolutionary theory.

  15. Acute ecological toxicity and environmental persistence of simulants

    SciTech Connect

    Cataldo, D.A.; Ligotke, M.W.; McVeety, B.D.; Fellows, R.J.; Bolton, H. Jr.; Li, S.W.; Van Voris, P.; Wentsel, R.S.

    1988-06-01

    The objectives of these studies are to establish the comparative environmental behavior and chemical fate of chemical simulants. Laboratory studies were undertaken to establish: (1) deposition efficiency (deposition velocities, Vd) for receptor surfaces including plant foliage and soils; (2) dose/response relationships for important environmental components including plants and soil microflora; and (3) the environmental persistence of the simulants. Chemical agent simulants are employed for a range of testing and training activities where use of chemical agents is less than suitable from a safety and environmental standpoint. A variety of chemical simulant materials are used to simulate either nerve agents or blister agents. The following research describes the environmental effects and persistence of four simulants. These are the nerve agent stimulants diisopropyl methylphosphonate (DIMP), diisopropyl fluorophosphate (DFP), and bis (2-ethylhexyl) phosphonate (BIS), and the mustard stimulant 2-chloroethyl ethyl sulfide (CEES). The vapor pressures for DIMP, DFP, and CEES are relatively high, reported to be 0.17, 0.58 and 3.4 mm Hg, respectively; while that of BIS is substantially less at 5.8 /times/ 10/sup /minus/5/ mm Hg at 25/degree/C. The chemical characteristics of DFP and CEES are very similar to G/VX-agents and mustard, respectively, and are employed for materials evaluation under controlled conditions. However, their toxicity precludes their use in the environment. DIMP and BIS are currently used for testing in the open air. 3 figs., 3 tabs.

  16. Climate and atmosphere simulator for experiments on ecological systems in changing environments.

    PubMed

    Verdier, Bruno; Jouanneau, Isabelle; Simonnet, Benoit; Rabin, Christian; Van Dooren, Tom J M; Delpierre, Nicolas; Clobert, Jean; Abbadie, Luc; Ferrière, Régis; Le Galliard, Jean-François

    2014-01-01

    Grand challenges in global change research and environmental science raise the need for replicated experiments on ecosystems subjected to controlled changes in multiple environmental factors. We designed and developed the Ecolab as a variable climate and atmosphere simulator for multifactor experimentation on natural or artificial ecosystems. The Ecolab integrates atmosphere conditioning technology optimized for accuracy and reliability. The centerpiece is a highly contained, 13-m(3) chamber to host communities of aquatic and terrestrial species and control climate (temperature, humidity, rainfall, irradiance) and atmosphere conditions (O2 and CO2 concentrations). Temperature in the atmosphere and in the water or soil column can be controlled independently of each other. All climatic and atmospheric variables can be programmed to follow dynamical trajectories and simulate gradual as well as step changes. We demonstrate the Ecolab's capacity to simulate a broad range of atmospheric and climatic conditions, their diurnal and seasonal variations, and to support the growth of a model terrestrial plant in two contrasting climate scenarios. The adaptability of the Ecolab design makes it possible to study interactions between variable climate-atmosphere factors and biotic disturbances. Developed as an open-access, multichamber platform, this equipment is available to the international scientific community for exploring interactions and feedbacks between ecological and climate systems. PMID:24955649

  17. Advances in Violence and Trauma: Toward Comprehensive Ecological Models

    ERIC Educational Resources Information Center

    Hughes, Honore M.; Humphrey, Natalie N.; Weaver, Terri L.

    2005-01-01

    The most important things learned about violence and trauma in the past 20 years are that interpersonal violence is prevalent, with different forms co-occurring, and that victims' reactions are complex. Researchers are called to consider models that include the ecological context within which victims experience violence and trauma to gain a better…

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

    ERIC Educational Resources Information Center

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

    2006-01-01

    Based on Bronfenbrenner's (1999) ecological perspective, a longitudinal, prospective model of individual differences in the quality of home environment (Home Observation for Measurement of the Environment--HOME) was tested in a sample of 179 Brazilian children and their families. Perinatal measures of family socioeconomic status (SES) and child…

  19. 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...

  20. 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...

  1. 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...

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

    ERIC Educational Resources Information Center

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

    2010-01-01

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

  3. 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...

  4. 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...

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

    EPA Science Inventory

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

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

  7. 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...

  8. 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...

  9. 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...

  10. Contrail Modeling and Simulation

    NASA Astrophysics Data System (ADS)

    Paoli, Roberto; Shariff, Karim

    2016-01-01

    There is large uncertainty in the radiative forcing induced by aircraft contrails, particularly after they transform to cirrus. It has recently become possible to simulate contrail evolution for long periods after their formation. We review the main physical processes and simulation efforts in the four phases of contrail evolution, namely the jet, vortex, vortex dissipation, and diffusion phases. Recommendations for further work are given.

  11. [New experimental models in microbial ecology].

    PubMed

    Liz'ko, N N

    1989-06-01

    Peculiar features of dysbiosis development in persons under extreme conditions were studied. It was shown that a number of extreme factors participated in formation of dysbiotic disorders in intestinal microflora. Of paramount importance was the neuro-emotional stress. Lability of bifido- and lactoflora was considered as the starting mechanism in dysbacteriosis under the extreme conditions. In the experimental models with rats SPF and Primates during flights of biosatellites of the Kosmos series the role of indigenous++ microflora in maintaining the microecological homeostasis, as well as the need for development of artificial and controlled intestinal microflora promising in prophylaxis of dysbacteriosis under extreme conditions was shown. The theoretical and experimentally grounded necessity of maintaining constant intestine microbiocenosis was confirmed by the practice of using the system of measures for recovery, stabilization and optimization of microflora in persons under extreme conditions. PMID:2802876

  12. INTERPRETING ECOLOGICAL DIVERSITY INDICES APPLIED TO T-RFLP DATA: INSIGHTS FROM SIMULATED MICROBIAL COMMUNITIES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ecological diversity indices are frequently applied to molecular profiling methods, such as terminal restriction fragment length polymorphism (T-RFLP), in order to detect differences in diversity of the microbial communities sampled. We performed simulations to determine whether diversity indices c...

  13. 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...

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

    ERIC Educational Resources Information Center

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

    2010-01-01

    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…

  15. Modeling the ecological consequences of land-use policies in an urbanizing region.

    PubMed

    Conway, Tenley M; Lathrop, Richard G

    2005-03-01

    Insight into future land use and effective ways to control land-use change is crucial to addressing environmental change. A variety of growth-control policies have been adopted by municipal and regional governments within the United States to try to minimize the ecological impact of continued urbanization, but it is often unclear if those policies can meet the stated ecological goals. Land-use-change models provide a way to generate predictions of future change, while exploring the impact of different land-use policies before irreversible transformations occur. In this article, an approach to modeling land-use policies that focuses on their ecological consequences is described. The policy simulation approach was used to predict future land use in the Barnegat Bay and Mullica River watersheds, in southeastern New Jersey, USA. Four commonly used policies were considered: down-zoning, cluster development, wetlands/water buffers, and open space protection. The results of the analysis suggest that none of the policies modeled were able to alter future land-use patterns, raising questions about the effectiveness of commonly adopted land-use policies. However, the policy modeling approach used in this study proved to be a useful way to determine if adoption of a given policy could improve the likelihood of meeting ecological goals. PMID:15772716

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

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

    USGS Publications Warehouse

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

    2009-01-01

    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.

  19. Correlated percolation models of structured habitat in ecology

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    PubMed

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

    2013-04-01

    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

  1. Ecological dynamic model of grassland and its practical verification.

    PubMed

    Zeng, Xiaodong; Wang, Aihui; Zhao, Gang; Shen, Samuel S P; Zeng, Xubin; Zeng, Qingcun

    2005-02-01

    Based on the physico-biophysical considerations, mathematical analysis and some approximate formulations generally adopted in meteorology and ecology, an ecological dynamic model of grassland is developed. The model consists of three interactive variables, i.e. the biomass of living grass, the biomass of wilted grass, and the soil wetness. The major biophysical processes are represented in parameterization formulas, and the model parameters can be determined inversely by using the observational climatological and ecological data. Some major parameters are adjusted by this method to fit the data (although incomplete) in the Inner Mongolia grassland, and other secondary parameters are estimated through sensitivity studies. The model results are well agreed with reality, e.g., (i) the maintenance of grassland requires a minimum amount of annual precipitation (approximately 300 mm); (ii) there is a significant relationship between the annual precipitation and the biomass of living grass; and (iii) the overgrazing will eventually result in desertification. A specific emphasis is put on the shading effect of the wilted grass accumulated on the soil surface. It effectively reduces the soil surface temperature and the evaporation, hence benefits the maintenance of grassland and the reduction of water loss in the soil. PMID:15844356

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

    USGS Publications Warehouse

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

    2013-01-01

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

  3. Numerical wind speed simulation model

    SciTech Connect

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

    1981-09-01

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

  4. Applying ecological modeling to parenting for Australian refugee families.

    PubMed

    Grant, Julian; Guerin, Pauline B

    2014-10-01

    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

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

    USGS Publications Warehouse

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

    2013-01-01

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

  6. Simulation Models in Higher Education.

    ERIC Educational Resources Information Center

    Morrisseau, James J.

    1973-01-01

    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)

  7. So Many Variables: Joint Modeling in Community Ecology.

    PubMed

    Warton, David I; Blanchet, F Guillaume; O'Hara, Robert B; Ovaskainen, Otso; Taskinen, Sara; Walker, Steven C; Hui, Francis K C

    2015-12-01

    Technological advances have enabled a new class of multivariate models for ecology, with the potential now to specify a statistical model for abundances jointly across many taxa, to simultaneously explore interactions across taxa and the response of abundance to environmental variables. Joint models can be used for several purposes of interest to ecologists, including estimating patterns of residual correlation across taxa, ordination, multivariate inference about environmental effects and environment-by-trait interactions, accounting for missing predictors, and improving predictions in situations where one can leverage knowledge of some species to predict others. We demonstrate this by example and discuss recent computation tools and future directions. PMID:26519235

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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.

  9. Structural Equation Modeling: Applications in ecological and evolutionary biology research

    USGS Publications Warehouse

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

    2003-01-01

    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.

  10. Advancing Ecological Models to Compare Scale in Multi-Level Educational Change

    ERIC Educational Resources Information Center

    Woo, David James

    2016-01-01

    Education systems as units of analysis have been metaphorically likened to ecologies to model change. However, ecological models to date have been ineffective in modelling educational change that is multi-scale and occurs across multiple levels of an education system. Thus, this paper advances two innovative, ecological frameworks that improve on…

  11. Unifying wildfire models from ecology and statistical physics.

    PubMed

    Zinck, Richard D; Grimm, Volker

    2009-11-01

    Understanding the dynamics of wildfire regimes is crucial for both regional forest management and predicting global interactions between fire regimes and climate. Accordingly, spatially explicit modeling of forest fire ecosystems is a very active field of research, including both generic and highly specific models. There is, however, a second field in which wildfire has served as a metaphor for more than 20 years: statistical physics. So far, there has been only limited interaction between these two fields of wildfire modeling. Here we show that two typical generic wildfire models from ecology are structurally equivalent to the most commonly used model from statistical physics. All three models can be unified to a single model in which they appear as special cases of regrowth-dependent flammability. This local "ecological memory" of former fire events is key to self-organization in wildfire ecosystems. The unified model is able to reproduce three different patterns observed in real boreal forests: fire size distributions, fire shapes, and a hump-shaped relationship between disturbance intensity (average annual area burned) and diversity of succession stages. The unification enables us to bring together insights from both disciplines in a novel way and to identify limitations that provide starting points for further research. PMID:19799499

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  13. Automatic programming of simulation models

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Zhang, Wensheng; Chen, Hongfu; Wang, Mingsheng

    2009-07-01

    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.

  15. Simulation modeling of estuarine ecosystems

    NASA Technical Reports Server (NTRS)

    Johnson, R. W.

    1980-01-01

    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.

  16. Introducing MERGANSER: A Flexible Framework for Ecological Niche Modeling

    NASA Astrophysics Data System (ADS)

    Klawonn, M.; Dow, E. M.

    2015-12-01

    Ecological Niche Modeling (ENM) is a collection of techniques to find a "fundamental niche", the range of environmental conditions suitable for a species' survival in the absence of inter-species interactions, given a set of environmental parameters. Traditional approaches to ENM face a number of obstacles including limited data accessibility, data management problems, computational costs, interface usability, and model validation. The MERGANSER system, which stands for Modeling Ecological Residency Given A Normalized Set of Environmental Records, addresses these issues through powerful data persistence and flexible data access, coupled with a clear presentation of results and fine-tuned control over model parameters. MERGANSER leverages data measuring 72 weather related phenomena, land cover, soil type, population, species occurrence, general species information, and elevation, totaling over 1.5 TB of data. To the best of the authors' knowledge, MERGANSER uses higher-resolution spatial data sets than previously published models. Since MERGANSER stores data in an instance of Apache SOLR, layers generated in support of niche models are accessible to users via simplified Apache Lucene queries. This is made even simpler via an HTTP front end that generates Lucene queries automatically. Specifically, a user need only enter the name of a place and a species to run a model. Using this approach to synthesizing model layers, the MERGANSER system has successfully reproduced previously published niche model results with a simplified user experience. Input layers for the model are generated dynamically using OpenStreetMap and SOLR's spatial search functionality. Models are then run using either user-specified or automatically determined parameters after normalizing them into a common grid. Finally, results are visualized in the web interface, which allows for quick validation. Model results and all surrounding metadata are also accessible to the user for further study.

  17. TREAT Modeling and Simulation Strategy

    SciTech Connect

    DeHart, Mark David

    2015-09-01

    This report summarizes a four-phase process used to describe the strategy in developing modeling and simulation software for the Transient Reactor Test Facility. The four phases of this research and development task are identified as (1) full core transient calculations with feedback, (2) experiment modeling, (3) full core plus experiment simulation and (4) quality assurance. The document describes the four phases, the relationship between these research phases, and anticipated needs within each phase.

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

    NASA Astrophysics Data System (ADS)

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

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

  19. Modeling and Simulation at NASA

    NASA Technical Reports Server (NTRS)

    Steele, Martin J.

    2009-01-01

    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.

  20. Advanced Space Shuttle simulation model

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  1. Infrared simulation model SENSAT-2.

    PubMed

    Richter, R

    1987-06-15

    The computer model SENSAT-2 has been developed for remote sensing uses of passive sensors in the 1-28-, microm infrared spectral region. The model calculates the IR signature of up to three homogeneous objects in the instantaneous field of view of the sensor. For the atmospheric part, model LOWTRAN-6 is used within SENSAT-2. Model SENSAT-2 can be used for mission analysis of sensors on different platforms like groundbased, aircraft, or satellite. It is a useful design tool for simulating and assessing the radiometric relations that are indispensable in designing sensors. Further uses include the comparison of measurements with simulation results and the radiometric correction of measurements. PMID:20489878

  2. 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 ...

  3. 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 ...

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

    PubMed

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

    2012-01-19

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

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

    PubMed Central

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

    2012-01-01

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

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

    PubMed

    Dexter, Nick; McLeod, Steven R

    2015-05-01

    Ecological traps are habitat sinks that are preferred by dispersing animals but have higher mortality or reduced fecundity compared to source habitats. Theory suggests that if mortality rates are sufficiently high, then ecological traps can result in extinction. An ecological trap may be created when pest animals are controlled in one area, but not in another area of equal habitat quality, and when there is density-dependent immigration from the high-density uncontrolled area to the low-density controlled area. We used a logistic population model to explore how varying the proportion of habitat controlled, control mortality rate, and strength of density-dependent immigration for feral pigs could affect the long-term population abundance and time to extinction. Increasing control mortality, the proportion of habitat controlled and the strength of density-dependent immigration decreased abundance both within and outside the area controlled. At higher levels of these parameters, extinction was achieved for feral pigs. We extended the analysis with a more complex stochastic, interactive model of feral pig dynamics in the Australian rangelands to examine how the same variables as the logistic model affected long-term abundance in the controlled and uncontrolled area and time to extinction. Compared to the logistic model of feral pig dynamics, the stochastic interactive model predicted lower abundances and extinction at lower control mortalities and proportions of habitat controlled. To improve the realism of the stochastic interactive model, we substituted fixed mortality rates with a density-dependent control mortality function, empirically derived from helicopter shooting exercises in Australia. Compared to the stochastic interactive model with fixed mortality rates, the model with the density-dependent control mortality function did not predict as substantial decline in abundance in controlled or uncontrolled areas or extinction for any combination of variables

  7. Modeling ecological traps for the control of feral pigs

    PubMed Central

    Dexter, Nick; McLeod, Steven R

    2015-01-01

    Ecological traps are habitat sinks that are preferred by dispersing animals but have higher mortality or reduced fecundity compared to source habitats. Theory suggests that if mortality rates are sufficiently high, then ecological traps can result in extinction. An ecological trap may be created when pest animals are controlled in one area, but not in another area of equal habitat quality, and when there is density-dependent immigration from the high-density uncontrolled area to the low-density controlled area. We used a logistic population model to explore how varying the proportion of habitat controlled, control mortality rate, and strength of density-dependent immigration for feral pigs could affect the long-term population abundance and time to extinction. Increasing control mortality, the proportion of habitat controlled and the strength of density-dependent immigration decreased abundance both within and outside the area controlled. At higher levels of these parameters, extinction was achieved for feral pigs. We extended the analysis with a more complex stochastic, interactive model of feral pig dynamics in the Australian rangelands to examine how the same variables as the logistic model affected long-term abundance in the controlled and uncontrolled area and time to extinction. Compared to the logistic model of feral pig dynamics, the stochastic interactive model predicted lower abundances and extinction at lower control mortalities and proportions of habitat controlled. To improve the realism of the stochastic interactive model, we substituted fixed mortality rates with a density-dependent control mortality function, empirically derived from helicopter shooting exercises in Australia. Compared to the stochastic interactive model with fixed mortality rates, the model with the density-dependent control mortality function did not predict as substantial decline in abundance in controlled or uncontrolled areas or extinction for any combination of variables

  8. Modelling dendritic ecological networks in space: anintegrated network perspective

    USGS Publications Warehouse

    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

    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).

  9. Using a probabilistic approach in an ecological risk assessment simulation tool: test case for depleted uranium (DU).

    PubMed

    Fan, Ming; Thongsri, Tepwitoon; Axe, Lisa; Tyson, Trevor A

    2005-06-01

    A probabilistic approach was applied in an ecological risk assessment (ERA) to characterize risk and address uncertainty employing Monte Carlo simulations for assessing parameter and risk probabilistic distributions. This simulation tool (ERA) includes a Window's based interface, an interactive and modifiable database management system (DBMS) that addresses a food web at trophic levels, and a comprehensive evaluation of exposure pathways. To illustrate this model, ecological risks from depleted uranium (DU) exposure at the US Army Yuma Proving Ground (YPG) and Aberdeen Proving Ground (APG) were assessed and characterized. Probabilistic distributions showed that at YPG, a reduction in plant root weight is considered likely to occur (98% likelihood) from exposure to DU; for most terrestrial animals, likelihood for adverse reproduction effects ranges from 0.1% to 44%. However, for the lesser long-nosed bat, the effects are expected to occur (>99% likelihood) through the reduction in size and weight of offspring. Based on available DU data for the firing range at APG, DU uptake will not likely affect survival of aquatic plants and animals (<0.1% likelihood). Based on field and laboratory studies conducted at APG and YPG on pocket mice, kangaroo rat, white-throated woodrat, deer, and milfoil, body burden concentrations observed fall into the distributions simulated at both sites. PMID:15910910

  10. Homogenization of Large-Scale Movement Models in Ecology

    USGS Publications Warehouse

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

    2011-01-01

    A difficulty in using diffusion models to predict large scale animal population dispersal is that individuals move differently based on local information (as opposed to gradients) in differing habitat types. This can be accommodated by using ecological diffusion. However, real environments are often spatially complex, limiting application of a direct approach. Homogenization for partial differential equations has long been applied to Fickian diffusion (in which average individual movement is organized along gradients of habitat and population density). We derive a homogenization procedure for ecological diffusion and apply it to a simple model for chronic wasting disease in mule deer. Homogenization allows us to determine the impact of small scale (10-100 m) habitat variability on large scale (10-100 km) movement. The procedure generates asymptotic equations for solutions on the large scale with parameters defined by small-scale variation. The simplicity of this homogenization procedure is striking when compared to the multi-dimensional homogenization procedure for Fickian diffusion,and the method will be equally straightforward for more complex models. ?? 2010 Society for Mathematical Biology.

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

    SciTech Connect

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

    1995-05-22

    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.

  12. Land surface model (LSM version 1.0) for ecological, hydrological, and atmospheric studies: Technical description and user`s guide. Technical note

    SciTech Connect

    Bonan, G.B.

    1996-01-01

    This technical note describes version 1 of the LSM land surface model. In this model, land surface processes are described in terms of biophysical fluxes (latent heat, sensible heat, momentum, reflected solar radiation, emitted longwave radiation) and biochemical fluxes (CO2) that depend on the ecological and hydrologic state of the land. Consequently, ecological and hydrological sub-models are needed to simulate temporal changes in terrestrial biomass and water.

  13. Aquilegia: a new model for plant development, ecology, and evolution.

    PubMed

    Kramer, Elena M

    2009-01-01

    The lower eudicot genus Aquilegia holds enormous potential for investigating aspects of development, ecology, and evolution that are otherwise unrepresented among existing model systems. Its evolutionary history is of particular interest because it represents a phylogenetic midpoint between models such as Arabidopsis and Oryza but, at the same time, has experienced a recent adaptive radiation within the genus. To take advantage of these features, a collaborative group has developed a number of genetic and genomic resources for Aquilegia that have facilitated the study of its distinct morphology. This work has demonstrated that although the petaloid sepals of Aquilegia do not depend on B-class genes for their identity, these loci do control development of the petals, stamens, and novel staminodium. Overall, Aquilegia stands as a key example of the potential utility and speed of developing new genetic model systems. PMID:19575583

  14. Process-Driven Ecological Modeling for Landscape Change Analysis

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  15. Stochastic models: theory and simulation.

    SciTech Connect

    Field, Richard V., Jr.

    2008-03-01

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

  16. A model of ecological and evolutionary consequences of color polymorphism.

    PubMed

    Forsman, Anders; Ahnesjö, Jonas; Caesar, Sofia; Karlsson, Magnus

    2008-01-01

    We summarize direct and indirect effects on fitness components of animal color pattern and present a synthesis of theories concerning the ecological and evolutionary dynamics of chromatic multiple niche polymorphisms. Previous endeavors have aimed primarily at identifying conditions that promote the evolution and maintenance of polymorphisms. We consider in a conceptual model also the reciprocal influence of color polymorphism on population processes and propose that polymorphism entails selective advantages that may promote the ecological success of polymorphic species. The model begins with an evolutionary branching event from mono- to polymorphic condition that, under the influence of correlational selection, is predicted to promote the evolution of physical integration of coloration and other traits (cf. multi-trait coevolution and complex phenotypes). We propose that the coexistence within a population of alternative ecomorphs with coadapted gene complexes promotes utilization of diverse environmental resources, population stability and persistence, colonization success, and range expansions, and enhances the evolutionary potential and speciation. Conversely, we predict polymorphic populations to be less vulnerable to environmental change and at lower risk of range contractions and extinctions compared with monomorphic populations. We offer brief suggestions as to how these falsifiable predictions may be tested. PMID:18376544

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

    SciTech Connect

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

    1992-01-01

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

  18. Tree Modeling and Dynamics Simulation

    NASA Astrophysics Data System (ADS)

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

    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.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    USGS Publications Warehouse

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

    2005-01-01

    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.

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

    PubMed

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

    2005-11-11

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

  2. Evolutionary model on market ecology of investors and investments

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

    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.

  3. Automatic programming of simulation models

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  4. Ecological Risk Model of Childhood Obesity in Chinese Immigrant Children

    PubMed Central

    Zhou, Nan; Cheah, Charissa S. L.

    2015-01-01

    Chinese Americans are the largest and fastest growing Asian American subgroup, increasing about one-third during the 2000s. Despite the slender Asian stereotype, nearly one-third of 6-to-11 years old Chinese American children were found to be overweight (above the 85th percentile in BMI). Importantly, unique and severe health risks are associated with being overweight/obese in Chinese. Unfortunately, Chinese immigrant children have been neglected in the literature on obesity. This review aimed to identify factors at various levels of the ecological model that may place Chinese immigrant children at risk for being overweight/obese in the U.S. Key contextual factors at the micro-, meso-, exo-, macro- and chronosystem were identified guided by Bronfenbrenner’s ecological systems theory. The corresponding mediating and moderating processes among the factors were also reviewed and proposed. By presenting a conceptual framework and relevant research, this review can provide a basic framework for directing future interdisciplinary research in seeking solutions to childhood obesity within this understudied population. PMID:25728887

  5. Ecological risk model of childhood obesity in Chinese immigrant children.

    PubMed

    Zhou, Nan; Cheah, Charissa S L

    2015-07-01

    Chinese Americans are the largest and fastest growing Asian American subgroup, increasing about one-third during the 2000s. Despite the slender Asian stereotype, nearly one-third of 6-to-11 year old Chinese American children were found to be overweight (above the 85th percentile in BMI). Importantly, unique and severe health risks are associated with being overweight/obese in Chinese. Unfortunately, Chinese immigrant children have been neglected in the literature on obesity. This review aimed to identify factors at various levels of the ecological model that may place Chinese immigrant children at risk for being overweight/obese in the U.S. Key contextual factors at the micro-, meso-, exo-, macro- and chronosystem were identified guided by Bronfenbrenner's ecological systems theory. The corresponding mediating and moderating processes among the factors were also reviewed and proposed. By presenting a conceptual framework and relevant research, this review can provide a basic framework for directing future interdisciplinary research in seeking solutions to childhood obesity within this understudied population. PMID:25728887

  6. Economic Analysis. Computer Simulation Models.

    ERIC Educational Resources Information Center

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

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

  7. University Macro Analytic Simulation Model.

    ERIC Educational Resources Information Center

    Baron, Robert; Gulko, Warren

    The University Macro Analytic Simulation System (UMASS) has been designed as a forecasting tool to help university administrators budgeting decisions. Alternative budgeting strategies can be tested on a computer model and then an operational alternative can be selected on the basis of the most desirable projected outcome. UMASS uses readily…

  8. Niche and neutral models predict asymptotically equivalent species abundance distributions in high-diversity ecological communities

    PubMed Central

    Chisholm, Ryan A.; Pacala, Stephen W.

    2010-01-01

    A fundamental challenge in ecology is to understand the mechanisms that govern patterns of relative species abundance. Previous numerical simulations have suggested that complex niche-structured models produce species abundance distributions (SADs) that are qualitatively similar to those of very simple neutral models that ignore differences between species. However, in the absence of an analytical treatment of niche models, one cannot tell whether the two classes of model produce the same patterns via similar or different mechanisms. We present an analytical proof that, in the limit as diversity becomes large, a strong niche model give rises to exactly the same asymptotic form of SAD as the neutral model, and we verify the analytical predictions for a Panamanian tropical forest data set. Our results strongly suggest that neutral processes drive patterns of relative species abundance in high-diversity ecological communities, even when strong niche structure exists. However, neutral theory cannot explain what generates high diversity in the first place, and it may not be valid in low-diversity communities. Our results also confirm that neutral theory cannot be used to infer an absence of niche structure or to explain ecosystem function. PMID:20733073

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

    USGS Publications Warehouse

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

    2012-01-01

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

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

    USGS Publications Warehouse

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

    2012-01-01

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

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

    SciTech Connect

    Flamm, R.O. ); Gottfried, R. ); Lee, R.G.; Naiman, R.J. ); Turner, M.G. ); Wear, D. )

    1994-06-01

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

  12. Introducing BioSARN - an ecological niche model refinement tool.

    PubMed

    Heap, Marshall J

    2016-08-01

    Environmental niche modeling outputs a biological species' potential distribution. Further work is needed to arrive at a species' realized distribution. The Biological Species Approximate Realized Niche (BioSARN) application provides the ecological modeler with a toolset to refine Environmental niche models (ENMs). These tools include soil and land class filtering, niche area quantification and novelties like enhanced temporal corridor definition, and output to a high spatial resolution land class model. BioSARN is exemplified with a study on Fraser fir, a tree species with strong land class and edaphic correlations. Soil and land class filtering caused the potential distribution area to decline 17%. Enhanced temporal corridor definition permitted distinction of current, continuing, and future niches, and thus niche change and movement. Tile quantification analysis provided further corroboration of these trends. BioSARN does not substitute other established ENM methods. Rather, it allows the experimenter to work with their preferred ENM, refining it using their knowledge and experience. Output from lower spatial resolution ENMs to a high spatial resolution land class model is a pseudo high-resolution result. Still, it maybe the best that can be achieved until wide range high spatial resolution environmental data and accurate high precision species occurrence data become generally available. PMID:27547356

  13. Modeling and Simulation for Safeguards

    SciTech Connect

    Swinhoe, Martyn T.

    2012-07-26

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

  14. The HWVP availability simulation model

    SciTech Connect

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

    1994-12-31

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

  15. Multiscale Stochastic Simulation and Modeling

    SciTech Connect

    James Glimm; Xiaolin Li

    2006-01-10

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

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

    PubMed

    Johnson, Sandra; Mengersen, Kerrie

    2012-07-01

    The management of environmental problems is multifaceted, requiring varied and sometimes conflicting objectives and perspectives to be considered. Bayesian network (BN) modeling facilitates the integration of information from diverse sources and is well suited to tackling the management challenges of complex environmental problems. However, combining several perspectives in one model can lead to large, unwieldy BNs that are difficult to maintain and understand. Conversely, an oversimplified model may lead to an unrealistic representation of the environmental problem. Environmental managers require the current research and available knowledge about an environmental problem of interest to be consolidated in a meaningful way, thereby enabling the assessment of potential impacts and different courses of action. Previous investigations of the environmental problem of interest may have already resulted in the construction of several disparate ecological models. On the other hand, the opportunity may exist to initiate this modeling. In the first instance, the challenge is to integrate existing models and to merge the information and perspectives from these models. In the second instance, the challenge is to include different aspects of the environmental problem incorporating both the scientific and management requirements. Although the paths leading to the combined model may differ for these 2 situations, the common objective is to design an integrated model that captures the available information and research, yet is simple to maintain, expand, and refine. BN modeling is typically an iterative process, and we describe a heuristic method, the iterative Bayesian network development cycle (IBNDC), for the development of integrated BN models that are suitable for both situations outlined above. The IBNDC approach facilitates object-oriented BN (OOBN) modeling, arguably viewed as the next logical step in adaptive management modeling, and that embraces iterative development

  17. Collective Philanthropy: Describing and Modeling the Ecology of Giving

    PubMed Central

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

    2014-01-01

    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

  18. Assessment of Molecular Modeling & Simulation

    SciTech Connect

    2002-01-03

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

  19. Airborne castanea pollen forecasting model for ecological and allergological implementation.

    PubMed

    Astray, G; Fernández-González, M; Rodríguez-Rajo, F J; López, D; Mejuto, J C

    2016-04-01

    Castanea sativa Miller belongs to the natural vegetation of many European deciduous forests prompting impacts in the forestry, ecology, allergological and chestnut food industry fields. The study of the Castanea flowering represents an important tool for evaluating the ecological conservation of North-Western Spain woodland and the possible changes in the chestnut distribution due to recent climatic change. The Castanea pollen production and dispersal capacity may cause hypersensitivity reactions in the sensitive human population due to the relationship between patients with chestnut pollen allergy and a potential cross reactivity risk with other pollens or plant foods. In addition to Castanea pollen's importance as a pollinosis agent, its study is also essential in North-Western Spain due to the economic impact of the industry around the chestnut tree cultivation and its beekeeping interest. The aim of this research is to develop an Artificial Neural Networks for predict the Castanea pollen concentration in the atmosphere of the North-West Spain area by means a 20years data set. It was detected an increasing trend of the total annual Castanea pollen concentrations in the atmosphere during the study period. The Artificial Neural Networks (ANNs) implemented in this study show a great ability to predict Castanea pollen concentration one, two and three days ahead. The model to predict the Castanea pollen concentration one day ahead shows a high linear correlation coefficient of 0.784 (individual ANN) and 0.738 (multiple ANN). The results obtained improved those obtained by the classical methodology used to predict the airborne pollen concentrations such as time series analysis or other models based on the correlation of pollen levels with meteorological variables. PMID:26802339

  20. A new quantitative model of ecological compensation based on ecosystem capital in Zhejiang Province, China*

    PubMed Central

    Jin, Yan; Huang, Jing-feng; Peng, Dai-liang

    2009-01-01

    Ecological compensation is becoming one of key and multidiscipline issues in the field of resources and environmental management. Considering the change relation between gross domestic product (GDP) and ecological capital (EC) based on remote sensing estimation, we construct a new quantitative estimate model for ecological compensation, using county as study unit, and determine standard value so as to evaluate ecological compensation from 2001 to 2004 in Zhejiang Province, China. Spatial differences of the ecological compensation were significant among all the counties or districts. This model fills up the gap in the field of quantitative evaluation of regional ecological compensation and provides a feasible way to reconcile the conflicts among benefits in the economic, social, and ecological sectors. PMID:19353749

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

    PubMed Central

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

    2015-01-01

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

  2. Rethinking the linear regression model for spatial ecological data.

    PubMed

    Wagner, Helene H

    2013-11-01

    The linear regression model, with its numerous extensions including multivariate ordination, is fundamental to quantitative research in many disciplines. However, spatial or temporal structure in the data may invalidate the regression assumption of independent residuals. Spatial structure at any spatial scale can be modeled flexibly based on a set of uncorrelated component patterns (e.g., Moran's eigenvector maps, MEM) that is derived from the spatial relationships between sampling locations as defined in a spatial weight matrix. Spatial filtering thus addresses spatial autocorrelation in the residuals by adding such component patterns (spatial eigenvectors) as predictors to the regression model. However, space is not an ecologically meaningful predictor, and commonly used tests for selecting significant component patterns do not take into account the specific nature of these variables. This paper proposes "spatial component regression" (SCR) as a new way of integrating the linear regression model with Moran's eigenvector maps. In its unconditioned form, SCR decomposes the relationship between response and predictors by component patterns, whereas conditioned SCR provides an alternative method of spatial filtering, taking into account the statistical properties of component patterns in the design of statistical hypothesis tests. Application to the well-known multivariate mite data set illustrates how SCR may be used to condition for significant residual spatial structure and to identify additional predictors associated with residual spatial structure. Finally, I argue that all variance is spatially structured, hence spatial independence is best characterized by a lack of excess variance at any spatial scale, i.e., spatial white noise. PMID:24400490

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

    USGS Publications Warehouse

    Fletcher, R.J., Jr.; Acevedo, M.A.; Reichert, Brian E.; Pias, Kyle E.; Kitchens, W.M.

    2011-01-01

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

  4. Modeling Channelization in Coastal Wetlands with Ecological Feedbacks

    NASA Astrophysics Data System (ADS)

    Hughes, Z. J.; Mahadevan, A.; Pennings, S.; FitzGerald, D.

    2014-12-01

    In coastal wetlands in Georgia and South Carolina, dendritic channel networks are actively incising headward at the rate of nearly 2 m/yr. The future geomorphic evolution of these marshes remains in question as rates of relative sea-level rise increase. Our objective is to understand the mechanisms that lead to the evolution of these channel networks through field observations and modeling. We model the geomorphological evolution of tidal creeks by viewing the wetland as a permeable medium. The porosity of the medium affects its hydraulic conductivity, which in turn is altered by erosion. Our multiphase model spontaneously generates channelization and branching networks through flow and erosion. In our field studies, we find that crabs play an active role in grazing vegetation and in the bioturbation of sediments. These effects are incorporated in our model based on field and laboratory observations of crab behavior and its effects on the marsh. We find the erosional patterns and channelization are significantly altered by the faunal feedback. Crabs enhance the growth of channels, inducing the headward erosion of creeks where flow-induced stresses are weakest. They are instrumental in generating high rates of creek extension, which channelize the marsh more effectively in response to sea-level rise. This indicates that the evolution of coastal wetlands is responding to interactions between physics and ecology and highlights the importance of the faunal contribution to these feedbacks.

  5. Simulation Framework for Teaching in Modeling and Simulation Areas

    ERIC Educational Resources Information Center

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

    2008-01-01

    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…

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

    USGS Publications Warehouse

    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

    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.

  7. Standard for Models and Simulations

    NASA Technical Reports Server (NTRS)

    Steele, Martin J.

    2016-01-01

    This NASA Technical Standard establishes uniform practices in modeling and simulation to ensure essential requirements are applied to the design, development, and use of models and simulations (MS), while ensuring acceptance criteria are defined by the program project and approved by the responsible Technical Authority. It also provides an approved set of requirements, recommendations, and criteria with which MS may be developed, accepted, and used in support of NASA activities. As the MS disciplines employed and application areas involved are broad, the common aspects of MS across all NASA activities are addressed. The discipline-specific details of a given MS should be obtained from relevant recommended practices. The primary purpose is to reduce the risks associated with MS-influenced decisions by ensuring the complete communication of the credibility of MS results.

  8. Simulating spin models on GPU

    NASA Astrophysics Data System (ADS)

    Weigel, Martin

    2011-09-01

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

  9. Rule-based simulation models

    NASA Technical Reports Server (NTRS)

    Nieten, Joseph L.; Seraphine, Kathleen M.

    1991-01-01

    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.

  10. Simulation model for the closed plant experiment facility of CEEF.

    PubMed

    Abe, Koichi; Ishikawa, Yoshio; Kibe, Seishiro; Nitta, Keiji

    2005-01-01

    The Closed Ecology Experiment Facilities (CEEF) is a testbed for Controlled Ecological Life Support Systems (CELSS) investigations. CEEF including the physico-chemical material regenerative system has been constructed for the experiments of material circulation among plants, breeding animals and crew of CEEF. Because CEEF is a complex system, an appropriate schedule for the operation must be prepared in advance. The CEEF behavioral Prediction System, CPS, that will help to confirm the operation schedule, is under development. CPS will simulate CEEFs behavior with data (conditions of equipments, quantity of materials in tanks, etc.) of CEEF and an operation schedule that will be made by the operation team everyday, before the schedule will be carried out. The result of the simulation will show whether the operation schedule is appropriate or not. In order to realize CPS, models of the simulation program that is installed in CPS must mirror the real facilities of CEEF. For the first step of development, a flexible algorithm of the simulation program was investigated. The next step was development of a replicate simulation model of the material circulation system for the Closed Plant Experiment Facility (CPEF) that is a part of CEEF. All the parts of a real material circulation system for CPEF are connected together and work as a complex mechanism. In the simulation model, the system was separated into 38 units according to its operational segmentation. In order to develop each model for its corresponding unit, specifications for the model were fixed based on the specifications of the real part. These models were put into a simulation model for the system. PMID:16175692

  11. Simulation model for the closed plant experiment facility of CEEF

    NASA Astrophysics Data System (ADS)

    Abe, Koichi; Ishikawa, Yoshio; Kibe, Seishiro; Nitta, Keiji

    The Closed Ecology Experiment Facilities (CEEF) is a testbed for Controlled Ecological Life Support Systems (CELSS) investigations. CEEF including the physico-chemical material regenerative system has been constructed for the experiments of material circulation among plants, breeding animals and crew of CEEF. Because CEEF is a complex system, an appropriate schedule for the operation must be prepared in advance. The CEEF behavioral Prediction System, CPS, that will help to confirm the operation schedule, is under development. CPS will simulate CEEFs behavior with data (conditions of equipments, quantity of materials in tanks, etc.) of CEEF and an operation schedule that will be made by the operation team everyday, before the schedule will be carried out. The result of the simulation will show whether the operation schedule is appropriate or not. In order to realize CPS, models of the simulation program that is installed in CPS must mirror the real facilities of CEEF. For the first step of development, a flexible algorithm of the simulation program was investigated. The next step was development of a replicate simulation model of the material circulation system for the Closed Plant Experiment Facility (CPEF) that is a part of CEEF. All the parts of a real material circulation system for CPEF are connected together and work as a complex mechanism. In the simulation model, the system was separated into 38 units according to its operational segmentation. In order to develop each model for its corresponding unit, specifications for the model were fixed based on the specifications of the real part. These models were put into a simulation model for the system.

  12. Analysis of ecological transitions in the Black Sea during the last four decades: A modelling study

    NASA Astrophysics Data System (ADS)

    Akoglu, Ekin; Salihoglu, Baris; Oguz, Temel

    2010-05-01

    This work investigates the Black Sea ecosystem and the changes it had undergone in the second half of the 20th century from a fisheries perspective using Ecopath, a widely adopted fisheries model. Different states of the Black Sea ecosystem were modeled using 5 simulation scenarios: Simulation 1, represents the quasi-pristine conditions of the Black Sea ecosystem during early 1960's; Simulation 2, represents the over-enrichment period of the ecosystem during early 1980's before the fisheries collapse and the outburst of alien ctenophore Mnemiopsis leidyi; Simulation 3, represents the changes in the ecosystem along with the outburst of Mnemiopsis in 1989; Simulation 4, represents the aftermath effects in the components of the Black Sea ecosystem just after the collapse of the fisheries; and Simulation 5, represents the recovery period of the fish stocks in the very beginning of the 1990's. According to the results of the model runs, it was found that the Black Sea ecosystem in its quasi-pristine conditions during early 1960's was top-down controlled. The piscivorous pelagic fish and dolphins exerted predation pressure on small pelagic fish species and suppressed their over-development. Our findings suggest that after the removal of these top predators from the ecosystem due to fishing and whaling, the small pelagic fish species had the opportunity to thrive themselves along with the over-enrichment of the Black Sea and reached high biomass levels in 1980's. Small pelagic fishes prevailed in the Black Sea ecosystem until the highly debated outburst of alien ctenophore Mnemiopsis leidyi. In 1989, the biomass of small pelagic fish species declined drastically and their population did not recover until the very beginning of 1990's due to various ecological and anthropogenic effects put forward by the outcomes of the simulations.

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

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    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.

  14. [Ecological security early-warning in Zhoushan Islands based on variable weight model].

    PubMed

    Zhou, Bin; Zhong, Lin-sheng; Chen, Tian; Zhou, Rui

    2015-06-01

    Ecological security early warning, as an important content of ecological security research, is of indicating significance in maintaining regional ecological security. Based on driving force, pressure, state, impact and response (D-P-S-I-R) framework model, this paper took Zhoushan Islands in Zhejiang Province as an example to construct the ecological security early warning index system, test degrees of ecological security early warning of Zhoushan Islands from 2000 to 2012 by using the method of variable weight model, and forecast ecological security state of 2013-2018 by Markov prediction method. The results showed that the variable weight model could meet the study needs of ecological security early warning of Zhoushan Islands. There was a fluctuant rising ecological security early warning index from 0.286 to 0.484 in Zhoushan Islands between year 2000 and 2012, in which the security grade turned from "serious alert" into " medium alert" and the indicator light turned from "orange" to "yellow". The degree of ecological security warning was "medium alert" with the light of "yellow" for Zhoushan Islands from 2013 to 2018. These findings could provide a reference for ecological security maintenance of Zhoushan Islands. PMID:26572042

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

    EPA Science Inventory

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

  16. Interdisciplinary Industrial Ecology Education: Recommendations for an Inclusive Pedagogical Model

    ERIC Educational Resources Information Center

    Sharma, Archana

    2009-01-01

    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…

  17. Stability of ecological industry chain: an entropy model approach.

    PubMed

    Wang, Qingsong; Qiu, Shishou; Yuan, Xueliang; Zuo, Jian; Cao, Dayong; Hong, Jinglan; Zhang, Jian; Dong, Yong; Zheng, Ying

    2016-07-01

    A novel methodology is proposed in this study to examine the stability of ecological industry chain network based on entropy theory. This methodology is developed according to the associated dissipative structure characteristics, i.e., complexity, openness, and nonlinear. As defined in the methodology, network organization is the object while the main focus is the identification of core enterprises and core industry chains. It is proposed that the chain network should be established around the core enterprise while supplementation to the core industry chain helps to improve system stability, which is verified quantitatively. Relational entropy model can be used to identify core enterprise and core eco-industry chain. It could determine the core of the network organization and core eco-industry chain through the link form and direction of node enterprises. Similarly, the conductive mechanism of different node enterprises can be examined quantitatively despite the absence of key data. Structural entropy model can be employed to solve the problem of order degree for network organization. Results showed that the stability of the entire system could be enhanced by the supplemented chain around the core enterprise in eco-industry chain network organization. As a result, the sustainability of the entire system could be further improved. PMID:27055893

  18. Electricity Generation Cost Simulation Model

    Energy Science and Technology Software Center (ESTSC)

    2003-04-25

    The Electricity Generation Cost Simulation Model (GENSIM) is a user-friendly, high-level dynamic simulation model that calculates electricity production costs for variety of electricity generation technologies, including: pulverized coal, gas combustion turbine, gas combined cycle, nuclear, solar (PV and thermal), and wind. The model allows the user to quickly conduct sensitivity analysis on key variables, including: capital, O&M, and fuel costs; interest rates; construction time; heat rates; and capacity factors. The model also includes consideration ofmore » a wide range of externality costs and pollution control options for carbon dioxide, nitrogen oxides, sulfur dioxide, and mercury. Two different data sets are included in the model; one from the U.S. Department of Energy (DOE) and the other from Platt's Research Group. Likely users of this model include executives and staff in the Congress, the Administration and private industry (power plant builders, industrial electricity users and electric utilities). The model seeks to improve understanding of the economic viability of various generating technologies and their emission trade-offs. The base case results using the DOE data, indicate that in the absence of externality costs, or renewable tax credits, pulverized coal and gas combined cycle plants are the least cost alternatives at 3.7 and 3.5 cents/kwhr, respectively. A complete sensitivity analysis on fuel, capital, and construction time shows that these results coal and gas are much more sensitive to assumption about fuel prices than they are to capital costs or construction times. The results also show that making nuclear competitive with coal or gas requires significant reductions in capital costs, to the $1000/kW level, if no other changes are made. For renewables, the results indicate that wind is now competitive with the nuclear option and is only competitive with coal and gas for grid connected applications if one includes the federal production tax

  19. Electricity Generation Cost Simulation Model

    SciTech Connect

    2003-04-25

    The Electricity Generation Cost Simulation Model (GENSIM) is a user-friendly, high-level dynamic simulation model that calculates electricity production costs for variety of electricity generation technologies, including: pulverized coal, gas combustion turbine, gas combined cycle, nuclear, solar (PV and thermal), and wind. The model allows the user to quickly conduct sensitivity analysis on key variables, including: capital, O&M, and fuel costs; interest rates; construction time; heat rates; and capacity factors. The model also includes consideration of a wide range of externality costs and pollution control options for carbon dioxide, nitrogen oxides, sulfur dioxide, and mercury. Two different data sets are included in the model; one from the U.S. Department of Energy (DOE) and the other from Platt's Research Group. Likely users of this model include executives and staff in the Congress, the Administration and private industry (power plant builders, industrial electricity users and electric utilities). The model seeks to improve understanding of the economic viability of various generating technologies and their emission trade-offs. The base case results using the DOE data, indicate that in the absence of externality costs, or renewable tax credits, pulverized coal and gas combined cycle plants are the least cost alternatives at 3.7 and 3.5 cents/kwhr, respectively. A complete sensitivity analysis on fuel, capital, and construction time shows that these results coal and gas are much more sensitive to assumption about fuel prices than they are to capital costs or construction times. The results also show that making nuclear competitive with coal or gas requires significant reductions in capital costs, to the $1000/kW level, if no other changes are made. For renewables, the results indicate that wind is now competitive with the nuclear option and is only competitive with coal and gas for grid connected applications if one includes the federal production tax credit

  20. Using two-dimensional hydrodynamic models at scales of ecological importance

    NASA Astrophysics Data System (ADS)

    Crowder, D. W.; Diplas, P.

    2000-05-01

    Modeling of flow features that are important in assessing stream habitat conditions has been a long-standing interest of stream biologists. Recently, they have begun examining the usefulness of two-dimensional (2-D) hydrodynamic models in attaining this objective. Current modeling practices consider relatively long channel sections with their bathymetry represented in terms of large, macro-scale, topographic features. Meso-scale topographic features, such as boulders, root-wads and other obstructions are typically not considered in the modeling process. Instead, the overall effects of these flow obstructions are captured through increased values in the channel roughness parameters. Such an approach to 2-D modeling allows one to accurately predict average depth and velocity values; however, it is not capable of providing any information about the flow patterns in the vicinity of these obstructions. Biologists though have known that such meso-scale features and the complex velocity patterns generated by their presence, play an important role in the ecology of streams, and thus cannot be ignored. It is therefore evident that there is a need to develop better tools, capable of modeling flow characteristics at scales of ecological importance. The purpose of this study is to expand the utility of 2-D hydraulic models to capture these flow features that are critical for characterizing stream habitat conditions. There exists a paucity of research addressing what types of topographic features should be included in 2-D model studies and to what extent a boulder or series of exposed boulders can influence predicted flow conditions and traditional useable habitat computations. Moreover, little research has been performed to evaluate the impact mesh refinement has on model results in natural streams. Numerical simulations, based on a natural river channel containing several large boulders, indicate that explicitly modeling local obstructions/boulders can significantly impact

  1. SEMI Modeling and Simulation Roadmap

    SciTech Connect

    Hermina, W.L.

    2000-10-02

    With the exponential growth in the power of computing hardware and software, modeling and simulation is becoming a key enabler for the rapid design of reliable Microsystems. One vision of the future microsystem design process would include the following primary software capabilities: (1) The development of 3D part design, through standard CAD packages, with automatic design rule checks that guarantee the manufacturability and performance of the microsystem. (2) Automatic mesh generation, for 3D parts as manufactured, that permits computational simulation of the process steps, and the performance and reliability analysis for the final microsystem. (3) Computer generated 2D layouts for process steps that utilize detailed process models to generate the layout and process parameter recipe required to achieve the desired 3D part. (4) Science-based computational tools that can simulate the process physics, and the coupled thermal, fluid, structural, solid mechanics, electromagnetic and material response governing the performance and reliability of the microsystem. (5) Visualization software that permits the rapid visualization of 3D parts including cross-sectional maps, performance and reliability analysis results, and process simulation results. In addition to these desired software capabilities, a desired computing infrastructure would include massively parallel computers that enable rapid high-fidelity analysis, coupled with networked compute servers that permit computing at a distance. We now discuss the individual computational components that are required to achieve this vision. There are three primary areas of focus: design capabilities, science-based capabilities and computing infrastructure. Within each of these areas, there are several key capability requirements.

  2. Simulation and experimental studies of operators` decision styles and crew composition while using an ecological and traditional user interface for the control room of a nuclear power plant

    SciTech Connect

    Meshkati, N.; Buller, B.J.; Azadeh, M.A.

    1995-04-01

    The goal of this research is threefold: (1) use of the Skill-, Rule-, and Knowledge-based levels of cognitive control -- the SRK framework -- to develop an integrated information processing conceptual framework (for integration of workstation, job, and team design); (2) to evaluate the user interface component of this framework -- the Ecological display; and (3) to analyze the effect of operators` individual information processing behavior and decision styles on handling plant disturbances plus their performance on, and preference for, Traditional and Ecological user interfaces. A series of studies were conducted. In Part I, a computer simulation model and a mathematical model were developed. In Part II, an experiment was designed and conducted at the EBR-II plant of the Argonne National Laboratory-West in Idaho Falls, Idaho. It is concluded that: the integrated SRK-based information processing model for control room operations is superior to the conventional rule-based model; operators` individual decision styles and the combination of their styles play a significant role in effective handling of nuclear power plant disturbances; use of the Ecological interface results in significantly more accurate event diagnosis and recall of various plant parameters, faster response to plant transients, and higher ratings of subject preference; and operators` decision styles affect on both their performance and preference for the Ecological interface.

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

    USGS Publications Warehouse

    Royle, J. Andrew; Dorazio, Robert M.

    2008-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  5. Simulated annealing model of acupuncture

    NASA Astrophysics Data System (ADS)

    Shang, Charles; Szu, Harold

    2015-05-01

    The growth control singularity model suggests that acupuncture points (acupoints) originate from organizers in embryogenesis. Organizers are singular points in growth control. Acupuncture can cause perturbation of a system with effects similar to simulated annealing. In clinical trial, the goal of a treatment is to relieve certain disorder which corresponds to reaching certain local optimum in simulated annealing. The self-organizing effect of the system is limited and related to the person's general health and age. Perturbation at acupoints can lead a stronger local excitation (analogous to higher annealing temperature) compared to perturbation at non-singular points (placebo control points). Such difference diminishes as the number of perturbed points increases due to the wider distribution of the limited self-organizing activity. This model explains the following facts from systematic reviews of acupuncture trials: 1. Properly chosen single acupoint treatment for certain disorder can lead to highly repeatable efficacy above placebo 2. When multiple acupoints are used, the result can be highly repeatable if the patients are relatively healthy and young but are usually mixed if the patients are old, frail and have multiple disorders at the same time as the number of local optima or comorbidities increases. 3. As number of acupoints used increases, the efficacy difference between sham and real acupuncture often diminishes. It predicted that the efficacy of acupuncture is negatively correlated to the disease chronicity, severity and patient's age. This is the first biological - physical model of acupuncture which can predict and guide clinical acupuncture research.

  6. Modelling and simulation of radiotherapy

    NASA Astrophysics Data System (ADS)

    Kirkby, Norman F.

    2007-02-01

    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.

  7. Uterine Contraction Modeling and Simulation

    NASA Technical Reports Server (NTRS)

    Liu, Miao; Belfore, Lee A.; Shen, Yuzhong; Scerbo, Mark W.

    2010-01-01

    Building a training system for medical personnel to properly interpret fetal heart rate tracing requires developing accurate models that can relate various signal patterns to certain pathologies. In addition to modeling the fetal heart rate signal itself, the change of uterine pressure that bears strong relation to fetal heart rate and provides indications of maternal and fetal status should also be considered. In this work, we have developed a group of parametric models to simulate uterine contractions during labor and delivery. Through analysis of real patient records, we propose to model uterine contraction signals by three major components: regular contractions, impulsive noise caused by fetal movements, and low amplitude noise invoked by maternal breathing and measuring apparatus. The regular contractions are modeled by an asymmetric generalized Gaussian function and least squares estimation is used to compute the parameter values of the asymmetric generalized Gaussian function based on uterine contractions of real patients. Regular contractions are detected based on thresholding and derivative analysis of uterine contractions. Impulsive noise caused by fetal movements and low amplitude noise by maternal breathing and measuring apparatus are modeled by rational polynomial functions and Perlin noise, respectively. Experiment results show the synthesized uterine contractions can mimic the real uterine contractions realistically, demonstrating the effectiveness of the proposed algorithm.

  8. Plasma disruption modeling and simulation

    SciTech Connect

    Hassanein, A.

    1994-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  10. Locating Pleistocene Refugia: Comparing Phylogeographic and Ecological Niche Model Predictions

    PubMed Central

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

    2007-01-01

    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

  11. 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...

  12. A modular BLSS simulation model

    NASA Technical Reports Server (NTRS)

    Rummel, John D.; Volk, Tyler

    1987-01-01

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

  13. Modeling on an ecological food chain with recycling

    NASA Astrophysics Data System (ADS)

    Cai, Qinghua; Mohamad, Zakaria; Yuan, Yuan

    2012-12-01

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

  14. Ubiquitin: molecular modeling and simulations.

    PubMed

    Ganoth, Assaf; Tsfadia, Yossi; Wiener, Reuven

    2013-11-01

    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

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

    PubMed Central

    2011-01-01

    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

  16. 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...

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

    ERIC Educational Resources Information Center

    Stibbards, Adam; Puk, Tom

    2011-01-01

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

  18. The ecological effects of thermopeaking in Alpine streams in flume simulations

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    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.

  19. Georeferenced model simulations efficiently support targeted monitoring

    NASA Astrophysics Data System (ADS)

    Berlekamp, Jürgen; Klasmeier, Jörg

    2010-05-01

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

  20. Propulsion System Modeling and Simulation

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Biancalani, Tommaso; DeVille, Lee; Goldenfeld, Nigel

    2015-05-01

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

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

    PubMed

    Biancalani, Tommaso; DeVille, Lee; Goldenfeld, Nigel

    2015-05-01

    We develop a theoretical framework for analyzing ecological models with a multidimensional niche space. Our approach relies on the fact that ecological niches are described by sequences of symbols, which allows us to include multiple phenotypic traits. Ecological drivers, such as competitive exclusion, are modeled by introducing the Hamming distance between two sequences. We show that a suitable transform diagonalizes the community interaction matrix of these models, making it possible to predict the conditions for niche differentiation and, close to the instability onset, the asymptotically long time population distributions of niches. We exemplify our method using the Lotka-Volterra equations with an exponential competition kernel. PMID:26066119

  3. An approximate model for pulsar navigation simulation

    NASA Astrophysics Data System (ADS)

    Jovanovic, Ilija; Enright, John

    2016-02-01

    This paper presents an approximate model for the simulation of pulsar aided navigation systems. High fidelity simulations of these systems are computationally intensive and impractical for simulating periods of a day or more. Simulation of yearlong missions is done by abstracting navigation errors as periodic Gaussian noise injections. This paper presents an intermediary approximate model to simulate position errors for periods of several weeks, useful for building more accurate Gaussian error models. This is done by abstracting photon detection and binning, replacing it with a simple deterministic process. The approximate model enables faster computation of error injection models, allowing the error model to be inexpensively updated throughout a simulation. Testing of the approximate model revealed an optimistic performance prediction for non-millisecond pulsars with more accurate predictions for pulsars in the millisecond spectrum. This performance gap was attributed to noise which is not present in the approximate model but can be predicted and added to improve accuracy.

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

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

    A spatially resolved, eleven-box ecological model is presented for an Intermittently Closed and Open Lake or Lagoon (ICOLL), configured for Smiths Lake, NSW Australia. ICOLLs are characterised by low flow from the catchment and a dynamic sand bar blocking oceanic exchange, which creates two distinct phases - open and closed. The process descriptions in the ecological model are based on a combination of physical and physiological limits to the processes of nutrient uptake, light capture by phytoplankton and predator-prey interactions. An inverse model is used to calculate mixing coefficients from salinity observations. When compared to field data, the ecological model obtains a fit for salinity, nitrogen, phosphorus, chlorophyll a and zooplankton which is within 1.5 standard deviations of the mean of the field data. Simulations show that nutrient limitation (nitrogen and phosphorus) is the dominant factor limiting growth of the autotrophic state variables during both the open and closed phases of the lake. The model is characterised by strong oscillations in phytoplankton and zooplankton abundance, typical of predator-prey cycles. There is an increase in the productivity of phytoplankton and zooplankton during the open phase. This increased productivity is exported out of the lagoon with a net nitrogen export from water column variables of 489 and 2012 mol N d -1 during the two studied openings. The model is found to be most sensitive to the mortality and feeding efficiency of zooplankton.

  5. Aeroacoustic simulation for phonation modeling

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

  6. An Ecological Model of Child Maltreatment in a Canadian Province.

    ERIC Educational Resources Information Center

    Krishnan, Vijaya; Morrison, Kenneth B.

    1995-01-01

    This study employed an ecological perspective to predict variations in the rate of child abuse and neglect among children aged 0 to 19 years in Alberta, Canada, in 1986. Positive correlates of the child maltreatment rate included population change, unemployment rate, percent Native, and North West region of Alberta. Implications for assessing…

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

    PubMed

    Bush, Andrew M; Novack-Gottshall, Philip M

    2012-02-23

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

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

    NASA Technical Reports Server (NTRS)

    Wydeven, T. J.

    1983-01-01

    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).

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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

  10. Simulation model for the Closed Plant Experimental Facilities of CEEF

    NASA Astrophysics Data System (ADS)

    Abe, K.; Ishikawa, Y.; Kibe, S.; Nitta, K.

    The Closed Ecology Experiment Facilities (CEEF) is a testbed for CELSS investigations. CEEF including the physico-chemical material regenerative system has been constructed for the experiments of material circulation among plants, breeding animals, humans (crew of the CEEF). Because CEEF is a complex system, an appropriate schedule for the operation must be prepared in advance. The CEEF behavioral Prediction System, CPS, that will help to confirm the operation schedule, is under development. CPS will simulate CEEF's behavior with data (conditions of equipments, quantity of materials in tanks, etc.) of CEEF and an operation schedule that will be made by the operation team everyday, before the schedule will be carried out. The result of the simulation will show whether the operation schedule is appropriate or not. In order to realize CPS, models of the simulation program that is installed in CPS must mirror the real facilities of CEEF. A flexible algorithm for the first step of development of the simulation program was already investigated. The next step was development of a replicate simulation model of the material circulation system for the Closed Plant Experimental Facilities (CPEF) that is a part of CEEF. All the parts of real material circulation system for CPEF are connected together and work as a complex mechanism. In the simulation model, the system was separated into 38 units according to its operational segmentation. In order to develop each model for its corresponding unit, specifications for the model were fixed based on the specifications of the real part. These models were put into a simulation model for the system.

  11. Assessing uncertainties in a second-generation dynamic vegetation model caused by ecological scale limitations.

    PubMed

    Fisher, Rosie; McDowell, Nate; Purves, Drew; Moorcroft, Paul; Sitch, Stephen; Cox, Peter; Huntingford, Chris; Meir, Patrick; Woodward, F Ian

    2010-08-01

    *Second-generation Dynamic Global Vegetation Models (DGVMs) have recently been developed that explicitly represent the ecological dynamics of disturbance, vertical competition for light, and succession. Here, we introduce a modified second-generation DGVM and examine how the representation of demographic processes operating at two-dimensional spatial scales not represented by these models can influence predicted community structure, and responses of ecosystems to climate change. *The key demographic processes we investigated were seed advection, seed mixing, sapling survival, competitive exclusion and plant mortality. We varied these parameters in the context of a simulated Amazon rainforest ecosystem containing seven plant functional types (PFTs) that varied along a trade-off surface between growth and the risk of starvation induced mortality. *Varying the five unconstrained parameters generated community structures ranging from monocultures to equal co-dominance of the seven PFTs. When exposed to a climate change scenario, the competing impacts of CO(2) fertilization and increasing plant mortality caused ecosystem biomass to diverge substantially between simulations, with mid-21st century biomass predictions ranging from 1.5 to 27.0 kg C m(-2). *Filtering the results using contemporary observation ranges of biomass, leaf area index (LAI), gross primary productivity (GPP) and net primary productivity (NPP) did not substantially constrain the potential outcomes. We conclude that demographic processes represent a large source of uncertainty in DGVM predictions. PMID:20618912

  12. Ecologically-focused Calibration of Hydrological Models for Environmental Flow Applications

    NASA Astrophysics Data System (ADS)

    Adams, S. K.; Bledsoe, B. P.

    2015-12-01

    Hydrologic alteration resulting from watershed urbanization is a common cause of aquatic ecosystem degradation. Developing environmental flow criteria for urbanizing watersheds requires quantitative flow-ecology relationships that describe biological responses to streamflow alteration. Ideally, gaged flow data are used to develop flow-ecology relationships; however, biological monitoring sites are frequently ungaged. For these ungaged locations, hydrologic models must be used to predict streamflow characteristics through calibration and testing at gaged sites, followed by extrapolation to ungaged sites. Physically-based modeling of rainfall-runoff response has frequently utilized "best overall fit" calibration criteria, such as the Nash-Sutcliffe Efficiency (NSE), that do not necessarily focus on specific aspects of the flow regime relevant to biota of interest. This study investigates the utility of employing flow characteristics known a priori to influence regional biological endpoints as "ecologically-focused" calibration criteria compared to traditional, "best overall fit" criteria. For this study, 19 continuous HEC-HMS 4.0 models were created in coastal southern California and calibrated to hourly USGS streamflow gages with nearby biological monitoring sites using one "best overall fit" and three "ecologically-focused" criteria: NSE, Richards-Baker Flashiness Index (RBI), percent of time when the flow is < 1 cfs (%<1), and a Combined Calibration (RBI and %<1). Calibrated models were compared using calibration accuracy, environmental flow metric reproducibility, and the strength of flow-ecology relationships. Results indicate that "ecologically-focused" criteria can be calibrated with high accuracy and may provide stronger flow-ecology relationships than "best overall fit" criteria, especially when multiple "ecologically-focused" criteria are used in concert, despite inabilities to accurately reproduce additional types of ecological flow metrics to which the

  13. An introduction to enterprise modeling and simulation

    SciTech Connect

    Ostic, J.K.; Cannon, C.E.

    1996-09-01

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

  14. Structured building model reduction toward parallel simulation

    SciTech Connect

    Dobbs, Justin R.; Hencey, Brondon M.

    2013-08-26

    Building energy model reduction exchanges accuracy for improved simulation speed by reducing the number of dynamical equations. Parallel computing aims to improve simulation times without loss of accuracy but is poorly utilized by contemporary simulators and is inherently limited by inter-processor communication. This paper bridges these disparate techniques to implement efficient parallel building thermal simulation. We begin with a survey of three structured reduction approaches that compares their performance to a leading unstructured method. We then use structured model reduction to find thermal clusters in the building energy model and allocate processing resources. Experimental results demonstrate faster simulation and low error without any interprocessor communication.

  15. The big data-big model (BDBM) challenges in ecological research

    NASA Astrophysics Data System (ADS)

    Luo, Y.

    2015-12-01

    The field of ecology has become a big-data science in the past decades due to development of new sensors used in numerous studies in the ecological community. Many sensor networks have been established to collect data. For example, satellites, such as Terra and OCO-2 among others, have collected data relevant on global carbon cycle. Thousands of field manipulative experiments have been conducted to examine feedback of terrestrial carbon cycle to global changes. Networks of observations, such as FLUXNET, have measured land processes. In particular, the implementation of the National Ecological Observatory Network (NEON), which is designed to network different kinds of sensors at many locations over the nation, will generate large volumes of ecological data every day. The raw data from sensors from those networks offer an unprecedented opportunity for accelerating advances in our knowledge of ecological processes, educating teachers and students, supporting decision-making, testing ecological theory, and forecasting changes in ecosystem services. Currently, ecologists do not have the infrastructure in place to synthesize massive yet heterogeneous data into resources for decision support. It is urgent to develop an ecological forecasting system that can make the best use of multiple sources of data to assess long-term biosphere change and anticipate future states of ecosystem services at regional and continental scales. Forecasting relies on big models that describe major processes that underlie complex system dynamics. Ecological system models, despite great simplification of the real systems, are still complex in order to address real-world problems. For example, Community Land Model (CLM) incorporates thousands of processes related to energy balance, hydrology, and biogeochemistry. Integration of massive data from multiple big data sources with complex models has to tackle Big Data-Big Model (BDBM) challenges. Those challenges include interoperability of multiple

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  17. Space station models, mockups and simulators

    NASA Technical Reports Server (NTRS)

    Miller, K. H.; Osgood, A.

    1985-01-01

    Schematic outlines for space station models, mockups, and simulators are presented. The types of Boeing models, mockups, and simulators are given along with the classes and characteristics. The use of models in the 767 program is briefly given. Computerized human factors tools are outlined. The use of computer aided design and computer aided manufacturing in the approach for the space station is advocated.

  18. Predicting ecological roles in the rhizosphere using metabolome and transportome modeling

    SciTech Connect

    Larsen, Peter E.; Collart, Frank R.; Dai, Yang; Blanchard, Jeffrey L.

    2015-09-02

    The ability to obtain complete genome sequences from bacteria in environmental samples, such as soil samples from the rhizosphere, has highlighted the microbial diversity and complexity of environmental communities. New algorithms to analyze genome sequence information in the context of community structure are needed to enhance our understanding of the specific ecological roles of these organisms in soil environments. We present a machine learning approach using sequenced Pseudomonad genomes coupled with outputs of metabolic and transportomic computational models for identifying the most predictive molecular mechanisms indicative of a Pseudomonad’s ecological role in the rhizosphere: a biofilm, biocontrol agent, promoter of plant growth, or plant pathogen. Computational predictions of ecological niche were highly accurate overall with models trained on transportomic model output being the most accurate (Leave One Out Validation F-scores between 0.82 and 0.89). The strongest predictive molecular mechanism features for rhizosphere ecological niche overlap with many previously reported analyses of Pseudomonad interactions in the rhizosphere, suggesting that this approach successfully informs a system-scale level understanding of how Pseudomonads sense and interact with their environments. The observation that an organism’s transportome is highly predictive of its ecological niche is a novel discovery and may have implications in our understanding microbial ecology. The framework developed here can be generalized to the analysis of any bacteria across a wide range of environments and ecological niches making this approach a powerful tool for providing insights into functional predictions from bacterial genomic data.

  19. Predicting Ecological Roles in the Rhizosphere Using Metabolome and Transportome Modeling

    PubMed Central

    Larsen, Peter E.; Collart, Frank R.; Dai, Yang

    2015-01-01

    The ability to obtain complete genome sequences from bacteria in environmental samples, such as soil samples from the rhizosphere, has highlighted the microbial diversity and complexity of environmental communities. However, new algorithms to analyze genome sequence information in the context of community structure are needed to enhance our understanding of the specific ecological roles of these organisms in soil environments. We present a machine learning approach using sequenced Pseudomonad genomes coupled with outputs of metabolic and transportomic computational models for identifying the most predictive molecular mechanisms indicative of a Pseudomonad’s ecological role in the rhizosphere: a biofilm, biocontrol agent, promoter of plant growth, or plant pathogen. Computational predictions of ecological niche were highly accurate overall with models trained on transportomic model output being the most accurate (Leave One Out Validation F-scores between 0.82 and 0.89). The strongest predictive molecular mechanism features for rhizosphere ecological niche overlap with many previously reported analyses of Pseudomonad interactions in the rhizosphere, suggesting that this approach successfully informs a system-scale level understanding of how Pseudomonads sense and interact with their environments. The observation that an organism’s transportome is highly predictive of its ecological niche is a novel discovery and may have implications in our understanding microbial ecology. The framework developed here can be generalized to the analysis of any bacteria across a wide range of environments and ecological niches making this approach a powerful tool for providing insights into functional predictions from bacterial genomic data. PMID:26332409

  20. 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...

  1. Survey of models/simulations at RADC

    NASA Astrophysics Data System (ADS)

    Denz, M. L.

    1982-11-01

    A survey was conducted to evaluate the current state of the art and technology of model/simulation capabilities at Rome Air Development Center, Griffiss AFB, NY. This memo presents a tabulation of 28 such models/simulations. These models/simulations are being used within RADC in the development and evaluations of Command, Control, Communications and Intelligence (C3I) technology. The results of this survey are incorporated in this memo.

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

    NASA Astrophysics Data System (ADS)

    Gelpi-Rodriguez, Phaedra

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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.

  4. Calibration and analysis of genome-based models for microbial ecology

    PubMed Central

    Louca, Stilianos; Doebeli, Michael

    2015-01-01

    Microbial ecosystem modeling is complicated by the large number of unknown parameters and the lack of appropriate calibration tools. Here we present a novel computational framework for modeling microbial ecosystems, which combines genome-based model construction with statistical analysis and calibration to experimental data. Using this framework, we examined the dynamics of a community of Escherichia coli strains that emerged in laboratory evolution experiments, during which an ancestral strain diversified into two coexisting ecotypes. We constructed a microbial community model comprising the ancestral and the evolved strains, which we calibrated using separate monoculture experiments. Simulations reproduced the successional dynamics in the evolution experiments, and pathway activation patterns observed in microarray transcript profiles. Our approach yielded detailed insights into the metabolic processes that drove bacterial diversification, involving acetate cross-feeding and competition for organic carbon and oxygen. Our framework provides a missing link towards a data-driven mechanistic microbial ecology. DOI: http://dx.doi.org/10.7554/eLife.08208.001 PMID:26473972

  5. Theory, Modeling, and Simulation of Semiconductor Lasers

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  6. Evaluating uncertainty in stochastic simulation models

    SciTech Connect

    McKay, M.D.

    1998-02-01

    This paper discusses fundamental concepts of uncertainty analysis relevant to both stochastic simulation models and deterministic models. A stochastic simulation model, called a simulation model, is a stochastic mathematical model that incorporates random numbers in the calculation of the model prediction. Queuing models are familiar simulation models in which random numbers are used for sampling interarrival and service times. Another example of simulation models is found in probabilistic risk assessments where atmospheric dispersion submodels are used to calculate movement of material. For these models, randomness comes not from the sampling of times but from the sampling of weather conditions, which are described by a frequency distribution of atmospheric variables like wind speed and direction as a function of height above ground. A common characteristic of simulation models is that single predictions, based on one interarrival time or one weather condition, for example, are not nearly as informative as the probability distribution of possible predictions induced by sampling the simulation variables like time and weather condition. The language of model analysis is often general and vague, with terms having mostly intuitive meaning. The definition and motivations for some of the commonly used terms and phrases offered in this paper lead to an analysis procedure based on prediction variance. In the following mathematical abstraction the authors present a setting for model analysis, relate practical objectives to mathematical terms, and show how two reasonable premises lead to a viable analysis strategy.

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

    PubMed Central

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Sawada, Yohei; Koike, Toshio

    2014-07-01

    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.

  9. A Generic Multibody Parachute Simulation Model

    NASA Technical Reports Server (NTRS)

    Neuhaus, Jason Richard; Kenney, Patrick Sean

    2006-01-01

    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.

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

    PubMed

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

    2000-06-01

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

  11. [Assessment on the ecological suitability in Zhuhai City, Guangdong, China, based on minimum cumulative resistance model].

    PubMed

    Li, Jian-fei; Li, Lin; Guo, Luo; Du, Shi-hong

    2016-01-01

    Urban landscape has the characteristics of spatial heterogeneity. Because the expansion process of urban constructive or ecological land has different resistance values, the land unit stimulates and promotes the expansion of ecological land with different intensity. To compare the effect of promoting and hindering functions in the same land unit, we firstly compared the minimum cumulative resistance value of promoting and hindering functions, and then looked for the balance of two landscape processes under the same standard. According to the ecology principle of minimum limit factor, taking the minimum cumulative resistance analysis method under two expansion processes as the evaluation method of urban land ecological suitability, this research took Zhuhai City as the study area to estimate urban ecological suitability by relative evaluation method with remote sensing image, field survey, and statistics data. With the support of ArcGIS, five types of indicators on landscape types, ecological value, soil erosion sensitivity, sensitivity of geological disasters, and ecological function were selected as input parameters in the minimum cumulative resistance model to compute urban ecological suitability. The results showed that the ecological suitability of the whole Zhuhai City was divided into five levels: constructive expansion prohibited zone (10.1%), constructive expansion restricted zone (32.9%), key construction zone (36.3%), priority development zone (2.3%), and basic cropland (18.4%). Ecological suitability of the central area of Zhuhai City was divided into four levels: constructive expansion prohibited zone (11.6%), constructive expansion restricted zone (25.6%), key construction zone (52.4%), priority development zone (10.4%). Finally, we put forward the sustainable development framework of Zhuhai City according to the research conclusion. On one hand, the government should strictly control the development of the urban center area. On the other hand, the

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

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

    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

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

    PubMed Central

    Skelly, Chris; Weinstein, Phil

    2003-01-01

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

  14. SSA Modeling and Simulation with DIRSIG

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  15. VHDL simulation with access to transistor models

    NASA Technical Reports Server (NTRS)

    Gibson, J.

    1991-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Mynnet, Arthur

    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.

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

    NASA Astrophysics Data System (ADS)

    Huang, Fang; Wang, Ping; Qi, Xin

    2014-11-01

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

  18. A model intercomparison for stochastic simulation of temporal precipitation

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  19. 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...

  20. Teaching Population Ecology Modeling by Means of the Hewlett-Packard 9100A.

    ERIC Educational Resources Information Center

    Tuinstra, Kenneth E.

    The incorporation of mathematical modeling experiences into an undergraduate biology course is described. Detailed expositions of three models used to teach concepts of population ecology are presented, including introductions to major concepts, user instructions, trial data and problem sets. The models described are: 1) an exponential/logistic…

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

    ERIC Educational Resources Information Center

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

    2014-01-01

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

  2. 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 ...

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

    USGS Publications Warehouse

    Woodward, Andrea; Beever, Erik A.

    2011-01-01

    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

  4. Resist profile simulation with fast lithography model

    NASA Astrophysics Data System (ADS)

    He, Yan-Ying; Chou, Chih-Shiang; Tang, Yu-Po; Huang, Wen-Chun; Liu, Ru-Gun; Gau, Tsai-Sheng

    2014-03-01

    A traditional approach to construct a fast lithographic model is to match wafer top-down SEM images, contours and/or gauge CDs with a TCC model plus some simple resist representation. This modeling method has been proven and is extensively used for OPC modeling. As the technology moves forward, this traditional approach has become insufficient in regard to lithography weak point detection, etching bias prediction, etc. The drawback of this approach is from metrology and simulation. First, top-down SEM is only good for acquiring planar CD information. Some 3D metrology such as cross-section SEM or AFM is necessary to obtain the true resist profile. Second, the TCC modeling approach is only suitable for planar image simulation. In order to model the resist profile, full 3D image simulation is needed. Even though there are many rigorous simulators capable of catching the resist profile very well, none of them is feasible for full-chip application due to the tremendous consumption of computational resource. The authors have proposed a quasi-3D image simulation method in the previous study [1], which is suitable for full-chip simulation with the consideration of sidewall angles, to improve the model accuracy of planar models. In this paper, the quasi-3D image simulation is extended to directly model the resist profile with AFM and/or cross-section SEM data. Resist weak points detected by the model generated with this 3D approach are verified on the wafer.

  5. Ongoing Ecological Divergence in an Emerging Genomic Model

    PubMed Central

    Arnegard, Matthew E.

    2009-01-01

    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

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

    PubMed

    Moskell, Christine; Allred, Shorna Broussard

    2013-03-01

    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

  7. 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...

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  9. It is the economy, stupid! Projecting the fate of fish populations using ecological-economic modeling.

    PubMed

    Quaas, Martin F; Reusch, Thorsten B H; Schmidt, Jörn O; Tahvonen, Olli; Voss, Rudi

    2016-01-01

    Four marine fish species are among the most important on the world market: cod, salmon, tuna, and sea bass. While the supply of North American and European markets for two of these species - Atlantic salmon and European sea bass - mainly comes from fish farming, Atlantic cod and tunas are mainly caught from wild stocks. We address the question what will be the status of these wild stocks in the midterm future, in the year 2048, to be specific. Whereas the effects of climate change and ecological driving forces on fish stocks have already gained much attention, our prime interest is in studying the effects of changing economic drivers, as well as the impact of variable management effectiveness. Using a process-based ecological-economic multispecies optimization model, we assess the future stock status under different scenarios of change. We simulate (i) technological progress in fishing, (ii) increasing demand for fish, and (iii) increasing supply of farmed fish, as well as the interplay of these driving forces under different scenarios of (limited) fishery management effectiveness. We find that economic change has a substantial effect on fish populations. Increasing aquaculture production can dampen the fishing pressure on wild stocks, but this effect is likely to be overwhelmed by increasing demand and technological progress, both increasing fishing pressure. The only solution to avoid collapse of the majority of stocks is institutional change to improve management effectiveness significantly above the current state. We conclude that full recognition of economic drivers of change will be needed to successfully develop an integrated ecosystem management and to sustain the wild fish stocks until 2048 and beyond. PMID:26348787

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

    SciTech Connect

    Sarmiento, Jorge L.; Gnanadesikan, Anand; Gruber, Nicolas; Jin, Xin; Armstrong, Robert

    2007-06-21

    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; and, 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

  11. Automated experimentation in ecological networks

    PubMed Central

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Hartwig, Melanie; Borchardt, Dietrich

    2010-05-01

    Fine sediments are a key constraint for the functions of a river. On the one hand they impact the light and heat regime and, consequently, the primary production. On the other hand they control the hydraulic connectivity of the hyporheic zone, determining residence time and oxygen availability and, hence, bio-geochemical reactions and habitat suitability. In turn, fine sediment delivery to and its fate in the aquatic system is a matter of catchment hydrology and erodability as well as transport capacity and load, respectively. This study aims to assess the influence of fine sediments on the aquatic system and the responses thereupon. The holistic modeling of fine sediment dynamics at catchment scale is challenging because of a lack of available information (input data), knowledge gaps in mathematical descriptions and the large range of spatiotemporal resolutions. In order to face these problems we approach to link distributed overland transport to in stream processes. Study site is the Kharaa river in northern Mongolia that shows a gradual degradation from pristine headwaters to disturbed lower reaches impacted by agricultural practices. Besides effects of climate change and population growth there are several pressures enhancing soil erosion from land surface or bank structures: deforestation and wildfires at headwater hill slopes, intensive grazing at floodplains, diminishing of riparian vegetation from downstream the mid reaches on and irrigated agriculture on vast stretches. Former investigations revealed deficits in benthic communities developed within the middle region and an increase in fine sediment colonisers. The part presented here concerns the water quality modeling using a compartmentalisation approach that describes the water column and sediment compartment at the same time. This is done according to the compendium described within the River Water Quality Model No.1 (RWQM1) and implemented through the AQUASIM Program for Identification and Simulation

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

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

  15. Using circuit theory to model connectivity in ecology, evolution, and conservation.

    PubMed

    McRae, Brad H; Dickson, Brett G; Keitt, Timothy H; Shah, Viral B

    2008-10-01

    Connectivity among populations and habitats is important for a wide range of ecological processes. Understanding, preserving, and restoring connectivity in complex landscapes requires connectivity models and metrics that are reliable, efficient, and process based. We introduce a new class of ecological connectivity models based in electrical circuit theory. Although they have been applied in other disciplines, circuit-theoretic connectivity models are new to ecology. They offer distinct advantages over common analytic connectivity models, including a theoretical basis in random walk theory and an ability to evaluate contributions of multiple dispersal pathways. Resistance, current, and voltage calculated across graphs or raster grids can be related to ecological processes (such as individual movement and gene flow) that occur across large population networks or landscapes. Efficient algorithms can quickly solve networks with millions of nodes, or landscapes with millions of raster cells. Here we review basic circuit theory, discuss relationships between circuit and random walk theories, and describe applications in ecology, evolution, and conservation. We provide examples of how circuit models can be used to predict movement patterns and fates of random walkers in complex landscapes and to identify important habitat patches and movement corridors for conservation planning. PMID:18959309

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

    NASA Technical Reports Server (NTRS)

    Volk, Tyler

    1987-01-01

    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.

  17. Ecological model of occupational stress. Application to urban firefighters.

    PubMed

    Salazar, M K; Beaton, R

    2000-10-01

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

  18. Protein Simulation Data in the Relational Model.

    PubMed

    Simms, Andrew M; Daggett, Valerie

    2012-10-01

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

  19. Protein Simulation Data in the Relational Model

    PubMed Central

    Simms, Andrew M.; Daggett, Valerie

    2011-01-01

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

  20. Simulation modeling for the health care manager.

    PubMed

    Kennedy, Michael H

    2009-01-01

    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

  1. Metabolic ecology.

    PubMed

    Humphries, Murray M; McCann, Kevin S

    2014-01-01

    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

  2. Predicting fish species distribution in estuaries: Influence of species' ecology in model accuracy

    NASA Astrophysics Data System (ADS)

    França, Susana; Cabral, Henrique N.

    2016-10-01

    Current threats to biodiversity, combined with limited data availability, have made for species distribution models (SDMs) to be increasingly used due to their ability to predict species' potential distribution, by relating species occurrence with environmental estimates. Often used in ecology, conservation biology and environmental management, SDMs have been informing conservation strategies, and thus it is becoming crucial to understand how trustworthy their predictions are. Uncertainty in model predictions is expected, but knowing the origin of prediction errors may help reducing it. Indeed, uncertainty may be related not only with data quality and the modelling algorithm used, but also with species ecological characteristics. To investigate whether the performance of SDM's may vary with species' ecological characteristics, distribution models for 21 fish species occurring in estuaries from the Portuguese coast were examined. These models were built at two distinct spatial resolutions and seven environmental explanatory variables were used as predictors. SDMs' accuracy was assessed with the area under the curve (AUC) of receiver operating characteristics (ROC) plots, sensitivity and specificity. Relationships between each measure of accuracy and species ecological characteristics were then examined. SDMs of the fish species presented small differences between the considered scales, and predictors as latitude, temperature and salinity were often selected at both scales. Measures of model accuracy presented differences between species and scales, but generally higher accuracy was obtained at smaller spatial scales. Among the ecological traits tested, species feeding mode and estuarine use functional groups were the most influential on the performance of distribution models. Habitat tolerance (number of habitat types frequented), species abundance, body size and spawning period also showed some effect. This analyses will contribute to distinguish, based on species

  3. 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...

  4. An Extensible Reduced Order Model Builder for Simulation and Modeling

    SciTech Connect

    2012-09-28

    REVEAL is a software framework for building reduced order models (surrogate models) for high fidelity complex scientific simulations. REVEAL is designed to do reduced order modeling and sensitivity analysis for scientific simulations. REVEAL incorporates a range of sampling and regression methods. It provides complete user environment and is adaptable to new simulators, runs jobs on any computing platform of choice, automatically post processes simulation results and provides a range of data analysis tools. The software is generic and can easily be extended to incorporate new methods, simulators.

  5. An Extensible Reduced Order Model Builder for Simulation and Modeling

    Energy Science and Technology Software Center (ESTSC)

    2012-09-28

    REVEAL is a software framework for building reduced order models (surrogate models) for high fidelity complex scientific simulations. REVEAL is designed to do reduced order modeling and sensitivity analysis for scientific simulations. REVEAL incorporates a range of sampling and regression methods. It provides complete user environment and is adaptable to new simulators, runs jobs on any computing platform of choice, automatically post processes simulation results and provides a range of data analysis tools. The softwaremore » is generic and can easily be extended to incorporate new methods, simulators.« less

  6. Range bagging: a new method for ecological niche modelling from presence-only data

    PubMed Central

    Drake, John M.

    2015-01-01

    The ecological niche is the set of environments in which a population of a species can persist without introduction of individuals from other locations. A good mathematical or computational representation of the niche is a prerequisite to addressing many questions in ecology, biogeography, evolutionary biology and conservation. A particularly challenging question for ecological niche modelling is the problem of presence-only modelling. That is, can an ecological niche be identified from records drawn only from the set of niche environments without records from non-niche environments for comparison? Here, I introduce a new method for ecological niche modelling from presence-only data called range bagging. Range bagging draws on the concept of a species' environmental range, but was inspired by the empirical performance of ensemble learning algorithms in other areas of ecological research. This paper extends the concept of environmental range to multiple dimensions and shows that range bagging is computationally feasible even when the number of environmental dimensions is large. The target of the range bagging base learner is an environmental tolerance of the species in a projection of its niche and is therefore an ecologically interpretable property of a species' biological requirements. The computational complexity of range bagging is linear in the number of examples, which compares favourably with the main alternative, Qhull. In conclusion, range bagging appears to be a reasonable choice for niche modelling in applications in which a presence-only method is desired and may provide a solution to problems in other disciplines where one-class classification is required, such as outlier detection and concept learning. PMID:25948612

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

    USGS Publications Warehouse

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

    2014-01-01

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

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

    SciTech Connect

    Brugger, K.E.; Tiebout, H.M. III |

    1994-12-31

    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.

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

    SciTech Connect

    Huston, M.A.

    1998-11-01

    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

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

    ERIC Educational Resources Information Center

    Hutzler, Yeshayahu

    2007-01-01

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

  11. COMPARING THE UTILITY OF MULTIMEDIA MODELS FOR HUMAN AND ECOLOGICAL EXPOSURE ANALYSIS: TWO CASES

    EPA Science Inventory

    A number of models are available for exposure assessment; however, few are used as tools for both human and ecosystem risks. This discussion will consider two modeling frameworks that have recently been used to support human and ecological decision making. The study will compare ...

  12. 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...

  13. Variable selection with random forest: Balancing stability, performance, and interpretation in ecological and environmental modeling

    EPA Science Inventory

    Random forest (RF) is popular in ecological and environmental modeling, in part, because of its insensitivity to correlated predictors and resistance to overfitting. Although variable selection has been proposed to improve both performance and interpretation of RF models, it is u...

  14. Software-Engineering Process Simulation (SEPS) model

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

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

    PubMed Central

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

    2015-01-01

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

  16. Simulation modeling and analysis with Arena

    SciTech Connect

    Tayfur Altiok; Benjamin Melamed

    2007-06-15

    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.

  17. A unifying framework for marine ecological model comparison

    NASA Astrophysics Data System (ADS)

    Fennel, Wolfgang; Osborn, Thomas

    2005-05-01

    The complex network of the marine food chain with all the details of the behavior of individuals and the interactions with physical processes cannot be included into one generic model. Modelling requires simplification and idealization. The reduction of complex problems to simpler, but tractable problems are guided by the questions being addressed. Consequently, a variety of different models have been developed with different choices of state variables, process formulations, and different degree of physical control. In the last decade a multitude of studies were based on biogeochemical models, population models, and individual based models. There are now models available that cover the full range from individual based models, to population models, to biomass models, to combinations thereof. The biological model components are linked to physical models ranging from 1d water column models to full 3d general circulation models. This paper attempts to develop an unifying theoretical framework that elucidates the relationships among the different classes of models. The theory is based on state densities, which characterize individuals in an abstract phase space. Integration of the state densities over spatial or biological variables relates population densities, abundance or biomass to individuals.

  18. Coupled Human-Ecological Dynamics and Land Degradation in Global Drylands-A modelling approach (Invited)

    NASA Astrophysics Data System (ADS)

    Helldén, U.

    2009-12-01

    Drylands comprise one-third of the Earth’s land area. They pose research, management, and policy challenges impacting the livelihoods of 2.5 billion people. Desertification is said to affect some 10-20% of the drylands and is assumed to expand with climate change and population growth. Recent paradigms stress the importance of understanding linkages between human-ecological (H-E) systems in order to achieve sustainable management policies. Understanding coupled H-E systems is difficult at local levels. It represents an even greater challenge at regional scales to guide priorities and policy decisions at national and international levels. System dynamic modelling may help facilitating the probblem. Desertification and land degradation are often modelled and mathematically defined in terms of soil erosion. The soil erosion process is usually described as a function of vegetation ground cover, rainfall characteristics, topography, soil characteristics and land management. On-going research based on system dynamic modelling, focussing on elucidating the inherent complexity of H-E systems across multiple scales, enables an assessment of the relative roles that climate, policy, management, land condition, vulnerability and human adaptation may play in desertification and dryland development. An early approach (1995) to study desertification through an H-E coupled model considered desertification to be stress beyond resilience, i.e. irreversible, using a predator-prey system approach. As most predator-prey models, it was based on two linked differential equations describing the evolution of both a human population (predator) and natural resources (prey) in terms of gains, losses and interaction. A recent effort used a model approach to assess desertification risk through system stability condition analysis. It is based on the assumption that soil erosion and the soil sub-system play an overriding final role in the desertification processes. It is stressing the role and

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

    USGS Publications Warehouse

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

    2010-01-01

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

  20. Predicting ecological roles in the rhizosphere using metabolome and transportome modeling

    DOE PAGESBeta

    Larsen, Peter E.; Collart, Frank R.; Dai, Yang; Blanchard, Jeffrey L.

    2015-09-02

    The ability to obtain complete genome sequences from bacteria in environmental samples, such as soil samples from the rhizosphere, has highlighted the microbial diversity and complexity of environmental communities. New algorithms to analyze genome sequence information in the context of community structure are needed to enhance our understanding of the specific ecological roles of these organisms in soil environments. We present a machine learning approach using sequenced Pseudomonad genomes coupled with outputs of metabolic and transportomic computational models for identifying the most predictive molecular mechanisms indicative of a Pseudomonad’s ecological role in the rhizosphere: a biofilm, biocontrol agent, promoter ofmore » plant growth, or plant pathogen. Computational predictions of ecological niche were highly accurate overall with models trained on transportomic model output being the most accurate (Leave One Out Validation F-scores between 0.82 and 0.89). The strongest predictive molecular mechanism features for rhizosphere ecological niche overlap with many previously reported analyses of Pseudomonad interactions in the rhizosphere, suggesting that this approach successfully informs a system-scale level understanding of how Pseudomonads sense and interact with their environments. The observation that an organism’s transportome is highly predictive of its ecological niche is a novel discovery and may have implications in our understanding microbial ecology. The framework developed here can be generalized to the analysis of any bacteria across a wide range of environments and ecological niches making this approach a powerful tool for providing insights into functional predictions from bacterial genomic data.« less

  1. Modeling and managing the interactions between hydrology, ecology and economics

    NASA Astrophysics Data System (ADS)

    Loucks, Daniel P.

    2006-09-01

    SummaryThis paper outlines a seven-step planning process being implemented on two large river basin studies currently underway in North America. One study involves the management of lake levels and flows in Lake Ontario and the St. Lawrence River on the border between Canada and the US. The International Joint Commission that oversees all water management issues between these two countries supports this study. The other involves the Greater Everglades region in south Florida in the US. In both studies multiple agencies and multiple stakeholders are involved in an attempt to find better ways of meeting multiple economic, environmental and ecological objectives. Both studies were motivated by the desire to find ways of improving the habitat of ecosystems within their basins and at the same time providing no less, or if possible greater, economic and social benefits that are derived from reliable water supplies, flows, levels, and flood protection. The seven-step planning process attempts to provide a very transparent and fully participatory approach toward reaching a common vision among all agencies and stakeholders as to how their hydrological system can be adaptively managed to better meet current and future objectives. This paper presents the seven steps and focuses on how all the values of various objectives are being defined and considered, together, in an attempt to define what water management policy works best and to an agreement on just what is 'best'.

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

    PubMed Central

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

    2012-01-01

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

  3. Rabi multi-sector reservoir simulation model

    SciTech Connect

    Bruijnzeels, C.; O`Halloran, C.

    1995-12-31

    To ensure optimum ultimate recovery of the 46 meter thick oil rim of the Rabi Field in Gabon, a full field simulation model was required. Due to it`s size and complexity, with local cusping, coning and geological circumstances dominating individual well behavior, a single full field model would be too large for existing hardware. A method was developed to simulate the full field with 5 separate sector models, whilst allowing the development in one sector model to have an effect on the boundary conditions of another sector. In this manner, the 13 x 4.5 km field could be simulated with a horizontal well spacing down to 175 meter. This paper focuses on the method used to attach single 3-phase tank cells to a sector simulation grid in order to represent non-simulated parts of the field. It also describes the history matching methodology and how to run a multisector model in forecasting mode. This method can be used for any reservoir, where size and complexity require large reservoir simulation models that normally could not be modeled within the constraints of available computer facilities. Detailed studies can be conducted on specific parts of a field, whilst allowing for dynamic flow and pressure effects caused by the rest of the field.

  4. Structural model uncertainty in stochastic simulation

    SciTech Connect

    McKay, M.D.; Morrison, J.D.

    1997-09-01

    Prediction uncertainty in stochastic simulation models can be described by a hierarchy of components: stochastic variability at the lowest level, input and parameter uncertainty at a higher level, and structural model uncertainty at the top. It is argued that a usual paradigm for analysis of input uncertainty is not suitable for application to structural model uncertainty. An approach more likely to produce an acceptable methodology for analyzing structural model uncertainty is one that uses characteristics specific to the particular family of models.

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

    SciTech Connect

    Not Available

    1993-05-01

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

  6. MODELING CONCEPTS FOR BMP/LID SIMULATION

    EPA Science Inventory

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

  7. A Simulation To Model Exponential Growth.

    ERIC Educational Resources Information Center

    Appelbaum, Elizabeth Berman

    2000-01-01

    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)

  8. 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...

  9. Mathematical Model Development and Simulation Support

    NASA Technical Reports Server (NTRS)

    Francis, Ronald C.; Tobbe, Patrick A.

    2000-01-01

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

  10. 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...

  11. ECOLOGICAL THEORY. A general consumer-resource population model.

    PubMed

    Lafferty, Kevin D; DeLeo, Giulio; Briggs, Cheryl J; Dobson, Andrew P; Gross, Thilo; Kuris, Armand M

    2015-08-21

    Food-web dynamics arise from predator-prey, parasite-host, and herbivore-plant interactions. Models for such interactions include up to three consumer activity states (questing, attacking, consuming) and up to four resource response states (susceptible, exposed, ingested, resistant). Articulating these states into a general model allows for dissecting, comparing, and deriving consumer-resource models. We specify this general model for 11 generic consumer strategies that group mathematically into predators, parasites, and micropredators and then derive conditions for consumer success, including a universal saturating functional response. We further show how to use this framework to create simple models with a common mathematical lineage and transparent assumptions. Underlying assumptions, missing elements, and composite parameters are revealed when classic consumer-resource models are derived from the general model. PMID:26293960

  12. Integrating evolution into ecological modelling: accommodating phenotypic changes in agent based models.

    PubMed

    Moustakas, Aristides; Evans, Matthew R

    2013-01-01

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

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

    PubMed Central

    Moustakas, Aristides; Evans, Matthew R.

    2013-01-01

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

  14. Minimum-complexity helicopter simulation math model

    NASA Technical Reports Server (NTRS)

    Heffley, Robert K.; Mnich, Marc A.

    1988-01-01

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

  15. The impacts of multiple stressors to model ecological structures

    SciTech Connect

    Landis, W.G.; Kelly, S.A.; Markiewicz, A.J.; Matthews, R.A.; Matthews, G.B.

    1995-12-31

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

  16. Modeling: The Role of Atomistic Simulations

    SciTech Connect

    Aga, Rachel S; Morris, James R

    2007-01-01

    A major advantage of atomistic simulations is that a detailed picture of the model under investigation is available, and so they have been very instrumental in explaining the connection of macroscopic properties to the atomic scale. Simulations play a significant role in the development and testing of theories. For example, simulations have been extensively used to test the mode-coupling theory (MCT). The theory predicts that at some critical temperature Tc, known as the mode-coupling temperature, the supercooled liquid undergoes a structural arrest, prohibiting the system from accessing all possible states, thus, essentially undergoing an ergodic to nonergodic transition. It gives definite predictions on various correlation functions that can be calculated directly in simulations. Simulations and MCT have played a tremendous role in elucidating a majority of what we now understand about the dynamics of glass-forming systems. Simulations can also be used to compare with experimental results to validate the model, so that one can use simulation results to measure properties not accessible to experiments. In many cases, as will be illustrated in the next sections, results of simulations motivate experimental investigations. Part of the goal of this chapter is to examine the contributions of atomic simulations to the current state of understanding of metallic glasses.

  17. The Ecological Model Web Concept: A Consultative Infrastructure for Decision Makers and Researchers

    NASA Astrophysics Data System (ADS)

    Geller, G.; Nativi, S.

    2011-12-01

    Rapid climate and socioeconomic changes may be outrunning society's ability to understand, predict, and respond to change effectively. Decision makers want better information about what these changes will be and how various resources will be affected, while researchers want better understanding of the components and processes of ecological systems, how they interact, and how they respond to change. Although there are many excellent models in ecology and related disciplines, there is only limited coordination among them, and accessible, openly shared models or model systems that can be consulted to gain insight on important ecological questions or assist with decision-making are rare. A "consultative infrastructure" that increased access to and sharing of models and model outputs would benefit decision makers, researchers, as well as modelers. Of course, envisioning such an ambitious system is much easier than building it, but several complementary approaches exist that could contribute. The one discussed here is called the Model Web. This is a concept for an open-ended system of interoperable computer models and databases based on making models and their outputs available as services ("model as a service"). Initially, it might consist of a core of several models from which it could grow gradually as new models or databases were added. However, a model web would not be a monolithic, rigidly planned and built system--instead, like the World Wide Web, it would grow largely organically, with limited central control, within a framework of broad goals and data exchange standards. One difference from the WWW is that a model web is much harder to create, and has more pitfalls, and thus is a long term vision. However, technology, science, observations, and models have advanced enough so that parts of an ecological model web can be built and utilized now, forming a framework for gradual growth as well as a broadly accessible infrastructure. Ultimately, the value of a model

  18. Modeling of transformers using circuit simulators

    SciTech Connect

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

    1994-07-01

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

  19. Intelligent Simulation Model To Facilitate EHR Training

    PubMed Central

    Mohan, Vishnu; Scholl, Gretchen; Gold, Jeffrey A.

    2015-01-01

    Despite the rapid growth of EHR use, there are currently no standardized protocols for EHR training. A simulation EHR environment may offer significant advantages with respect to EHR training, but optimizing the training paradigm requires careful consideration of the simulation model itself, and how it is to be deployed during training. In this paper, we propose Six Principles that are EHR-agnostic and provide the framework for the development of an intelligent simulation model that can optimize EHR training by replicating real-world clinical conditions and appropriate cognitive loads. PMID:26958229

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

    PubMed Central

    Slater, Hannah; Michael, Edwin

    2012-01-01

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

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

    PubMed

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

    2015-02-01

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

  2. A Model of the Textbook in the Ecology of Education.

    ERIC Educational Resources Information Center

    Thompson, Patricia J.

    This paper presents a model and conceptual framework for textbook research. The model will help scholars from a variety of disciplines approach textbook research from a common theoretical grounding and later compare and synthesize their findings using agreed-upon categories and a shared vocabulary. The author first describes two rudimentary models…

  3. An Ecological Model for the Processing of Symbolic Information.

    ERIC Educational Resources Information Center

    Bierschenk, Bernhard

    1982-01-01

    Cognitive model of processing symbolic information abstracted from verbal expressions should consider running text, not scattered sentences. A valid abstraction of information structures should be based on explicit encoding of intentionality and valuation. A model must cope with empirical context and novelty instead of truth-values in…

  4. Binary black hole simulations for surrogate modeling

    NASA Astrophysics Data System (ADS)

    Hemberger, Daniel; SXS Collaboration

    2016-03-01

    Analytic or data-driven models of binary black hole coalescences are used to densely cover the full parameter space, because it is computationally infeasible to do so using numerical relativity (NR). However, these models still need input from NR, either for calibration, or because the model is agnostic to the underlying physics. We use the Spectral Einstein Code (SpEC) to provide a large number of simulations to aid the construction of a NR surrogate model in a 5-dimensional subset of the parameter space. I will present an analysis of the simulations that were used to construct the surrogate model. I will also describe the infrastructure that was needed to efficiently perform a large number of simulations across many computational resources.

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

    EPA Science Inventory

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

  6. Importance of ocean circulation in ecological modeling: An example from the North Sea

    NASA Astrophysics Data System (ADS)

    Skogen, Morten D.; Moll, Andreas

    2005-09-01

    There is an increasing number of ecological models for the North Sea around. Skogen and Moll (2000) [Skogen, M.D., Moll, A. 2000. Interannual variability of the North Sea primary production: comparison from two model studies. Continental Shelf Research 20 (2), 129-151] compared the interannual variability of the North Sea primary production using two state-of-the-art ecological models, NORWECOM and ECOHAM1. Their conclusion was that the two models agreed on an annual mean primary production, its variability and the timing and size of the peak production. On the other hand, there was a low (even negative dependent of area) correlation in the production in different years between the two models. In the present work, these conclusions are brought further. To try to better understand the observed differences between the two models, the two ecological models are run in an identical physical setting. With such a set-up also the interannual variability between the two models is in agreement, and it is concluded that the single most important factor for a reliable modeling of phytoplankton and nutrient distributions and transports within the North Sea is a proper physical model.

  7. An approach to the mathematical modelling of a controlled ecological life support system

    NASA Technical Reports Server (NTRS)

    Averner, M. M.

    1981-01-01

    An approach to the design of a computer based model of a closed ecological life-support system suitable for use in extraterrestrial habitats is presented. The model is based on elemental mass balance and contains representations of the metabolic activities of biological components. The model can be used as a tool in evaluating preliminary designs for closed regenerative life support systems and as a method for predicting the behavior of such systems.

  8. 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...

  9. River system environmental modeling and simulation methodology

    SciTech Connect

    Rao, N.B.

    1981-01-01

    Several computer models have been built to examine pollution in rivers. However, the current state of the art in this field emphasizes problem solving using specific programs. A general methodology for building and simulating models of river systems is lacking. Thus, the purpose of this research was to develop a methodology which can be used to conceptualize, visualize, construct and analyze using simulation, models of pollution in river systems. The conceptualization and visualization of these models was facilitated through a network representation. The implementation of the models was accomplished using the capabilities of an existing simulation language, GASP V. The methodology also provides data management facilities for model outputs through the use of the Simulation Data Language (SDL), and high quality plotting facilities through the use of the graphics package DISSPLA (Display Integrated Software System and Plotting Language). Using this methodology, a river system is modeled as consisting of certain elements, namely reaches, junctions, dams, reservoirs, withdrawals and pollutant sources. All these elements of the river system are described in a standard form which has been implemented on a computer. This model, when executed, produces spatial and temporal distributions of the pollutants in the river system. Furthermore, these outputs can be stored in a database and used to produce high quality plots. The result of this research is a methodology for building, implementing and examining the results of models of pollution in river systems.

  10. Architecting a Simulation Framework for Model Rehosting

    NASA Technical Reports Server (NTRS)

    Madden, Michael M.

    2004-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Hristopulos, Dionissios

    2015-04-01

    The advent of the big data era creates new opportunities for environmental and ecological modelling but also presents significant challenges. The availability of remote sensing images and low-cost wireless sensor networks implies that spatiotemporal environmental data to cover larger spatial domains at higher spatial and temporal resolution for longer time windows. Handling such voluminous data presents several technical and scientific challenges. In particular, the geostatistical methods used to process spatiotemporal data need to overcome the dimensionality curse associated with the need to store and invert large covariance matrices. There are various mathematical approaches for addressing the dimensionality problem, including change of basis, dimensionality reduction, hierarchical schemes, and local approximations. We present a Stochastic Local Interaction (SLI) model that can be used to model local correlations in spatial data. SLI is a random field model suitable for data on discrete supports (i.e., regular lattices or irregular sampling grids). The degree of localization is determined by means of kernel functions and appropriate bandwidths. The strength of the correlations is determined by means of coefficients. In the "plain vanilla" version the parameter set involves scale and rigidity coefficients as well as a characteristic length. The latter determines in connection with the rigidity coefficient the correlation length of the random field. The SLI model is based on statistical field theory and extends previous research on Spartan spatial random fields [2,3] from continuum spaces to explicitly discrete supports. The SLI kernel functions employ adaptive bandwidths learned from the sampling spatial distribution [1]. The SLI precision matrix is expressed explicitly in terms of the model parameter and the kernel function. Hence, covariance matrix inversion is not necessary for parameter inference that is based on leave-one-out cross validation. This property

  12. Exploring an Ecological Model of Perceived Usability within a Multi-Tiered Vocabulary Intervention

    ERIC Educational Resources Information Center

    Neugebauer, Sabina R.; Chafouleas, Sandra M.; Coyne, Michael D.; McCoach, D. Betsy; Briesch, Amy M.

    2016-01-01

    The present study examines an ecological model for intervention use to explain student vocabulary performance in a multi-tiered intervention setting. A teacher self-report measure composed of factors hypothesized to influence intervention use at multiple levels (i.e., individual, intervention, and system level) was administered to 54 teachers and…

  13. Molecular tools and bumble bees: revealing hidden details of ecology and evolution in a model system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bumble bees are a longstanding model system for studies on behavior, ecology, and evolution, due to their well-studied social lifestyle, invaluable roles as both wild and managed pollinators, and their ubiquity and diversity across temperate ecosystems. Yet despite their importance, many aspects of ...

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

    ERIC Educational Resources Information Center

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

    2011-01-01

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

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

    ERIC Educational Resources Information Center

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

    2012-01-01

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

  16. Applying the Social Ecological Model to Creating Asthma-Friendly Schools in Louisiana

    ERIC Educational Resources Information Center

    Nuss, Henry J.; Hester, Laura L.; Perry, Mark A.; Stewart-Briley, Collette; Reagon, Valamar M.; Collins, Pamela

    2016-01-01

    Background: In 2010, the Louisiana Asthma Management and Prevention Program (LAMP) implemented the Asthma-Friendly Schools Initiative in high-risk Louisiana populations. The social ecological model (SEM) was used as a framework for an asthma program implemented in 70 state K-12 public schools over 2 years. Methods: Activities included a needs…

  17. An Ecological Model of Externalizing Behaviors in African-American Adolescents: No Family Is an Island.

    ERIC Educational Resources Information Center

    Mason, Craig A.; And Others

    1994-01-01

    Examined the utility of a 2-step ecological model in predicting externalizing behavior among 144 African American seventh and eighth graders. Found that parental work environment and parental social support had an indirect impact on externalizing by influencing the microsystem variables of parental warmth, parental use of restrictive control, and…

  18. 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...

  19. Application of the Rangeland Hydrology and Erosion Model to Ecological Site Descriptions and Management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The utility of Ecological Site Descriptions (ESDs) and State-and-Transition Models (STMs) concepts in guiding rangeland management hinges on their ability to accurately describe and predict community dynamics and the associated consequences. For many rangeland ecosystems, plant community dynamics ar...

  20. 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...

  1. The Expansion of National Educational Systems: Tests of a Population Ecology Model

    ERIC Educational Resources Information Center

    Nielsen, Francois; Hannan, Michael T.

    1977-01-01

    This paper investigates the expansion of enrollments in national systems of education during the 1950-1970 period from the point of view of the population ecology of organizations. A simplified dynamic model of the growth of a population of educational organizations is estimated using various techniques for pooling time series of data. (Author/JM)

  2. Female-Headed Families: An Ecological Model of Residential Concentration in a Small City.

    ERIC Educational Resources Information Center

    And Others; Roncek, Dennis W.

    1980-01-01

    Proposed an ecological model to explain the concentration of female-headed families in a small city. Data for city blocks provided patterns of concentration. Of the physical variables, only historical development of the city and market decisions by nonresidential consumers were important predictors of concentration; spatial concentration was not…

  3. Ecological niche modeling of Coccidioides spp. in western North American deserts.

    PubMed

    Baptista-Rosas, Raúl C; Hinojosa, Alejandro; Riquelme, Meritxell

    2007-09-01

    Coccidioidomycosis is an endemic infectious disease in western North American deserts caused by the dimorphic ascomycete Coccidioides spp. Even though there has been an increase in the number of reported cases in the last years, few positive isolations have been obtained from soil samples in endemic areas for the disease. This low correlation between epidemiological and environmental data prompted us to better characterize the fundamental ecological niche of this important fungal pathogen. By using a combination of environmental variables and geospatially referenced points, where positive isolations had been obtained in southern California and Arizona (USA) and Sonora (Mexico), we have applied Genetic Algorithm for Rule Set Production (GARP) and Geographical Information Systems (GIS) to characterize the most likely ecological conditions favorable for the presence of the fungus. This model, based on environmental variables, allowed us to identify hotspots for the presence of the fungus in areas of southern California, Arizona, Texas, Baja California, and northern Mexico, whereas an alternative model based on bioclimatic variables gave us much broader probable distribution areas. We have overlapped the hotspots obtained with the environmental model with the available epidemiological information and have found a high match. Our model suggests that the most probable fundamental ecological niche for Coccidioides spp. is found in the arid lands of the North American deserts and provides the methodological basis to further characterize the realized ecological niche of Coccidioides spp., which would ultimately contribute to design smart field-sampling strategies. PMID:17395734

  4. Culture Specific Approaches to the Treatment of Latin Multiple Substance Abusers: Family and Ecological Intervention Models.

    ERIC Educational Resources Information Center

    Szapocznik, Jose; And Others

    Four models developed for the treatment of Cuban American adult and adolescent drug and alcohol abusers are discussed in this paper. The study reviewed was aimed at (1) investigating the effectiveness of "Ecological Family Systems Therapy," an approach created by the Spanish Family Guidance Clinic in Miami, Florida, and (2) identifying the…

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

    ERIC Educational Resources Information Center

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

    2006-01-01

    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…

  6. Using Teacher-Generated Ecological Models to Assess Knowledge Gained During Teacher Training

    NASA Astrophysics Data System (ADS)

    Dresner, M.; Moldenke, A.

    2005-12-01

    Developing a capacity for systems thinking (ways to understand complex systems) requires both immersion in challenging, real-world problem contexts and exposure to systems analysis language, tools and procedures, such as ecosystem modeling. Modeling is useful as a means of conveying complex, dynamic interactions. Models of ecosystems can facilitate an ability to be attentive to whole systems by illustrating multiple factors of interaction, feedback, subsystems and inputs and outputs, which lead to a greater understanding of ecosystem functioning. Concept mapping, which uses models of students' ideas organized hierarchically is used in assessment, but it does not having any outside utility. Ecosystem models, on the other hand, are legitimate end-products in and of themselves. A change made in a learner-generated model that conforms to patterns observed in nature by the learner can be seen as reflections of his or her understanding. Starting with their own reflections on previous ecological knowledge, teachers will model components of the ecosystem they are about to study. 'Teaching models' will be used to familiarize learners with the symbolic language of models and to teach some basic ecology concepts. Teachers then work directly with ecologists in conducting research, using the steps of a straightforward study as a guide, and then observe and discuss patterns in the data they have collected. Higher-order thinking skills are practiced through the reflective use of ecological models. Through a series of questions including analysis, relational reasoning, synthesis, testing, and explaining, pairs of teacher describe the principles and theories about ecology that they think might be operating in their models to one another. They describe the consequences of human-caused impacts and possible causal patterns. They explain any differences in their understanding of ecosystem interactions before and after their research experiences

  7. Atmospheric model intercomparison project: Monsoon simulations

    SciTech Connect

    Sperber, K.R.; Palmer, T.N.

    1994-06-01

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

  8. Revolutions in energy through modeling and simulation

    SciTech Connect

    Tatro, M.; Woodard, J.

    1998-08-01

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

  9. Electrical Load Modeling and Simulation

    SciTech Connect

    Chassin, David P.

    2013-01-01

    Electricity consumer demand response and load control are playing an increasingly important role in the development of a smart grid. Smart grid load management technologies such as Grid FriendlyTM controls and real-time pricing are making their way into the conventional model of grid planning and operations. However, the behavior of load both affects, and is affected by load control strategies that are designed to support electric grid planning and operations. This chapter discussed the natural behavior of electric loads, how it interacts with various load control and demand response strategies, what the consequences are for new grid operation concepts and the computing issues these new technologies raise.

  10. Agent-based modeling to simulate the dengue spread

    NASA Astrophysics Data System (ADS)

    Deng, Chengbin; Tao, Haiyan; Ye, Zhiwei

    2008-10-01

    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.

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

    PubMed

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

    2012-08-01

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

  12. Non-linear transformer modeling and simulation

    SciTech Connect

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

    1994-08-01

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

  13. Rotor systems research aircraft simulation mathematical model

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    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.

  14. Estimating solar radiation for plant simulation models

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  15. Modeling and simulation of metal forming equipment

    NASA Astrophysics Data System (ADS)

    Frazier, W. G.; Medina, E. A.; Malas, J. C.; Irwin, R. D.

    1997-04-01

    The demand for components made from hard-to-form materials is growing, as is the need to better understand and improve the control of metal forming equipment. Techniques are presented for developing accurate models and computer simulations of metal forming equipment for the purpose of improving metal forming process design. Emphasis is placed on modeling the dynamic behavior of hydraulic vertical forge presses, although similar principles apply to other types of metal forming equipment. These principles are applied to modeling and simulation of a 1000 ton forge press in service at Wright-Patterson Air Force Base, Ohio, along with experimental verification.

  16. Molecular simulation and modeling of complex I.

    PubMed

    Hummer, Gerhard; Wikström, Mårten

    2016-07-01

    Molecular modeling and molecular dynamics simulations play an important role in the functional characterization of complex I. With its large size and complicated function, linking quinone reduction to proton pumping across a membrane, complex I poses unique modeling challenges. Nonetheless, simulations have already helped in the identification of possible proton transfer pathways. Simulations have also shed light on the coupling between electron and proton transfer, thus pointing the way in the search for the mechanistic principles underlying the proton pump. In addition to reviewing what has already been achieved in complex I modeling, we aim here to identify pressing issues and to provide guidance for future research to harness the power of modeling in the functional characterization of complex I. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt. PMID:26780586

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

    PubMed

    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

    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

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

    USGS Publications Warehouse

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

    2015-01-01

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

  19. A queuing model for road traffic simulation

    SciTech Connect

    Guerrouahane, N.; Aissani, D.; Bouallouche-Medjkoune, L.; Farhi, N.

    2015-03-10

    We present in this article a stochastic queuing model for the raod traffic. The model is based on the M/G/c/c state dependent queuing model, and is inspired from the deterministic Godunov scheme for the road traffic simulation. We first propose a variant of M/G/c/c state dependent model that works with density-flow fundamental diagrams rather than density-speed relationships. We then extend this model in order to consider upstream traffic demand as well as downstream traffic supply. Finally, we show how to model a whole raod by concatenating raod sections as in the deterministic Godunov scheme.

  20. PIXE simulation: Models, methods and technologies

    SciTech Connect

    Batic, M.; Pia, M. G.; Saracco, P.; Weidenspointner, G.

    2013-04-19

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

  1. Mars Smart Lander Parachute Simulation Model

    NASA Technical Reports Server (NTRS)

    Queen, Eric M.; Raiszadeh, Ben

    2002-01-01

    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.

  2. Adding more ecology into species delimitation: ecological niche models and phylogeography help define cryptic species in the black salamander (Aneides flavipunctatus).

    PubMed

    Rissler, Leslie J; Apodaca, Joseph J

    2007-12-01

    Being able to efficiently and accurately delimit species is one of the most basic and important aspects of systematics because species are the fundamental unit of analysis in biogeography, ecology, and conservation. We present a rationale and approach for combining ecological niche modeling, spatially explicit analyses of environmental data, and phylogenetics in species delimitation, and we use our methodology in an empirical example focusing on Aneides flavipunctatus, the black salamander (Caudata: Plethodontidae), in California. We assess the relationships between genetic, environmental, and geographic distance among populations. We use 11 climatic variables and point locality data from public databases to create ecological niche models. The suitability of potential contact zones between parapatric lineages is also assessed using the data from ecological niche modeling. Phylogenetic analyses of portions of the mitochondrial genome reveal morphologically cryptic mitochondrial lineages in this species. In addition, we find that patterns of genetic divergence are strongly associated with divergence in the ecological niche. Our work demonstrates the ease and utility of using spatial analyses of environmental data and phylogenetics in species delimitation, especially for groups displaying fine-scaled endemism and cryptic species. PMID:18066928

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

    SciTech Connect

    Kercher, J.R.

    1994-06-01

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

  4. Ecological Models and Methods in the Study of School Psychology.

    ERIC Educational Resources Information Center

    Scott, Myrtle

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

  5. Beyond Cultural Relativism: An Ecological Model for Rhetorical Ethics.

    ERIC Educational Resources Information Center

    Mackin, Jim

    A model intended to overcome the cultural relativism of determining what is an ethical act draws an analogy to environmental studies. Beginning with the concepts of "telos" (final purpose) and "archai" (priority), the notion of an ecosystem of ethics avoids limitation to a particular historical definition of good. Since the telos of human life is…

  6. 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...

  7. Understanding the Codevelopment of Modeling Practice and Ecological Knowledge

    ERIC Educational Resources Information Center

    Manz, Eve

    2012-01-01

    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…

  8. Cognitive Niches: An Ecological Model of Strategy Selection

    ERIC Educational Resources Information Center

    Marewski, Julian N.; Schooler, Lael J.

    2011-01-01

    How do people select among different strategies to accomplish a given task? Across disciplines, the strategy selection problem represents a major challenge. We propose a quantitative model that predicts how selection emerges through the interplay among strategies, cognitive capacities, and the environment. This interplay carves out for each…

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

    ERIC Educational Resources Information Center

    Fluellen, Jerry

    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,…

  10. Power electronics system modeling and simulation

    SciTech Connect

    Lai, Jih-Sheng

    1994-12-31

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

  11. Five forest harvesting simulation models, part 1: modeling characteristics

    SciTech Connect

    Goulet, D.V.; Iff, R.H.; Sirois, D.L.

    1980-01-01

    This paper is the first of two describing the conclusions from a study to determine the state of the art in timber harvesting computer simulation modeling. Five models were evaluated -- Forest Harvesting Simulation Model (FHSM), Full Tree Field Chipping (FTFC), Harvesting System Simulator (HSS), Simulation Applied to Logging Systems (SAPLOS), and Timber Harvesting and Transport Simulator (THATS) -- for their potential use in southern forest harvesting operations. In Part I, modeling characteristics and overall model philosophy are identified and illustrated. This includes a detailed discussion of the wood flow process in each model, accounting strategies for productive/non-productive times, performance variables, and the different types of harvesting systems modelable. In Part II we discuss user implementation problems. Those dealt with in detail are: What questions can be asked of the model. What are the modeling tradeoffs, and how do they impact on the analysis. What are the computer skills necessary to effectively work with the model. What computer support is needed. Are the models operational. The results provide a good picture of the state of the art in timber harvesting computer simulation. Much learning has occurred in the generation of these models, and many modeling and implementation problems have been uncovered, some of which remain unsolved. Hence, the user needs to examine closely the model and the intended application so that results will represent usable, valid data. It is recommended that the development of timber harvesting computer simulation modeling continue, so that existing and proposed timber harvesting strategies can be adequately evaluated. A set of design criteria are proposed. (Refs. 21).

  12. Great Basin land management planning using ecological modeling.

    PubMed

    Forbis, Tara A; Provencher, Louis; Frid, Leonardo; Medlyn, Gary

    2006-07-01

    This report describes a land management modeling effort that analyzed potential impacts of proposed actions under an updated Bureau of Land Management Resource Management Plan that will guide management for 20 years on 4.6 million hectares in the Great Basin ecoregion of the United States. State-and-transition models that included vegetation data, fire histories, and many parameters (i.e., rates of succession, fire return intervals, outcomes of management actions, and invasion rates of native and nonnative invasive species) were developed through workshops with scientific experts and range management specialists. Alternative restoration scenarios included continuation of current management, full fire suppression, wildfire use in designated fire use zones, wildfire use in resilient vegetation types only, restoration with a tenfold budget increase, no restoration treatments, and no livestock grazing. Under all the scenarios, cover of vegetation states with native perennial understory declined and was replaced by tree-invaded and weed-dominated states. The greatest differences among alternative management scenarios resulted from the use of fire as a tool to maintain native understory. Among restoration scenarios, only the scenario assuming a tenfold budget increase had a more desirable outcome than the current management scenario. Removal of livestock alone had little effect on vegetation resilience. Rather, active restoration was required. The predictive power of the model was limited by current understanding of Great Basin vegetation dynamics and data needs including statistically valid monitoring of restoration treatments, invasiveness and invasibility, and fire histories. The authors suggest that such computer models can be useful tools for systematic analysis of potential impacts in land use planning. However, for a modeling effort to be productive, the management situation must be conducive to open communication among land management agencies and partner

  13. Great Basin Land Management Planning Using Ecological Modeling

    NASA Astrophysics Data System (ADS)

    Forbis, Tara A.; Provencher, Louis; Frid, Leonardo; Medlyn, Gary

    2006-07-01

    This report describes a land management modeling effort that analyzed potential impacts of proposed actions under an updated Bureau of Land Management Resource Management Plan that will guide management for 20 years on 4.6 million hectares in the Great Basin ecoregion of the United States. State-and-transition models that included vegetation data, fire histories, and many parameters (i.e., rates of succession, fire return intervals, outcomes of management actions, and invasion rates of native and nonnative invasive species) were developed through workshops with scientific experts and range management specialists. Alternative restoration scenarios included continuation of current management, full fire suppression, wildfire use in designated fire use zones, wildfire use in resilient vegetation types only, restoration with a tenfold budget increase, no restoration treatments, and no livestock grazing. Under all the scenarios, cover of vegetation states with native perennial understory declined and was replaced by tree-invaded and weed-dominated states. The greatest differences among alternative management scenarios resulted from the use of fire as a tool to maintain native understory. Among restoration scenarios, only the scenario assuming a tenfold budget increase had a more desirable outcome than the current management scenario. Removal of livestock alone had little effect on vegetation resilience. Rather, active restoration was required. The predictive power of the model was limited by current understanding of Great Basin vegetation dynamics and data needs including statistically valid monitoring of restoration treatments, invasiveness and invasibility, and fire histories. The authors suggest that such computer models can be useful tools for systematic analysis of potential impacts in land use planning. However, for a modeling effort to be productive, the management situation must be conducive to open communication among land management agencies and partner

  14. Statistical Properties of Downscaled CMIP3 Global Climate Model Simulations

    NASA Astrophysics Data System (ADS)

    Duffy, P.; Tyan, S.; Thrasher, B.; Maurer, E. P.; Tebaldi, C.

    2009-12-01

    Spatial downscaling of global climate model projections adds physically meaningful spatial detail, and brings the results down to a scale that is more relevant to human and ecological systems. Statistical/empirical downscaling methods are computationally inexpensive, and thus can be applied to large ensembles of global climate model projections. Here we examine some of the statistical properties of a large ensemble of empirically downscale global climate projections. The projections are the CMIP3 global climate model projections that were performed by modeling groups around the world and archived by the Program for Climate Model Diagnosis and Intercomparison at Lawrence Livermore National Laboratory. Downscaled versions of 112 of these simulations were created on 2007 and are archived at http://gdo-dcp.ucllnl.org/downscaled_cmip3_projections/dcpInterface.html. The downscaling methodology employed, “Bias Correction/Spatial Downscaling” (BCSD), includes a correction of GCM biases relative to observations during a historical reference period, as well as empirical downscaling to grid scale of ~12 km. We analyzed these downscaled projections and some of the original global model results to assess effects of the bias correction and downscaling on the statistical properties of the ensemble. We also assessed uncertainty in the climate response to increased greenhouse gases from initial conditions relative to the uncertainty introduced by choice of global climate model.

  15. Modeling and simulation of plasma processing equipment

    NASA Astrophysics Data System (ADS)

    Kim, Heon Chang

    Currently plasma processing technology is utilized in a wide range of applications including advanced Integrated Circuit (IC) fabrication. Traditionally, plasma processing equipments have been empirically designed and optimized at great expense of development time and cost. This research proposes the development of a first principle based, multidimensional plasma process simulator with the aim of enhancing the equipment design procedure. The proposed simulator accounts for nonlinear interactions among various plasma chemistry and physics, neutral chemistry and transport, and dust transport phenomena. A three moment modeling approach is employed that shows good predictive capabilities at reasonable computational expense. For numerical efficiency, various versions of explicit and implicit Essentially Non- Oscillatory (ENO) algorithms are employed. For the rapid evaluation of time-periodic steady-state solutions, a feedback control approach is employed. Two dimensional simulation results of capacitively coupled rf plasmas show that ion bombardment uniformity can be improved through simulation based design of the plasma process. Through self-consistent simulations of an rf triode, it is also shown that effects of secondary rf voltage and frequency on ion bombardment energy can be accurately captured. These results prove that scaling relations among important process variables can be identified through the three moment modeling and simulation approach. Through coupling of the plasma model with a neutral chemistry and transport model, spatiotemporal distributions of both charged and uncharged species, including metastables, are predicted for an oxygen plasma. Furthermore, simulation results also verify the existence of a double layer in this electronegative plasma. Through Lagrangian simulation of dust in a plasma reactor, it is shown that small particles are accumulate near the center and the radial sheath boundary depending on their initial positions while large

  16. Pressurized Cadaver Model in Cardiothoracic Surgical Simulation.

    PubMed

    Greene, Christina L; Minneti, Michael; Sullivan, Maura E; Baker, Craig J

    2015-09-01

    Simulation is increasingly recognized as an integral aspect of thoracic surgery education. A number of simulators have been introduced to teach component cardiothoracic skills; however, no good model exists for numerous essential skills including redo sternotomy and internal mammary artery takedown. These procedures are often relegated to thoracic surgery residents but have significant negative implications if performed incorrectly. Fresh tissue dissection is recognized as the gold standard for surgical simulation, but the lack of circulating blood volume limits surgical realism. Our aim is to describe the technique of the pressurized cadaver for use in cardiothoracic surgical procedures, focusing on internal mammary artery takedown. PMID:26354651

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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

  18. 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...

  19. Coupling Ecology and River Dynamics using a Simplified Interaction Model

    NASA Astrophysics Data System (ADS)

    Longjas, A.; Czuba, J. A.; Schwenk, J.; Danesh Yazdi, M.; Hansen, A.; Foufoula-Georgiou, E.

    2013-12-01

    Quantifying how changes in streamflow and sediment affect riverine life is an important component of river basin management and stream restoration efforts, especially under human and climate-induced changes affecting many basins around the world. In the Midwestern US, drastic changes in mussel populations have been witnessed over the past decade begging quantitative understanding of cause and effect and attribution of these changes to the concurrent changes in streamflow and sediment loads to the rivers. Previous empirical analyses have attempted to explore mussel abundance with habitat associations and bulk hydrologic and geomorphic attributes as predictors but results showed relatively weak relationships and low predictive power. In this work, we developed a process-based model that incorporates water-sediment-mussel interactions using functional relationships and predicts the long-term trends of suspended-sediment, chlorophyll-a and mussel population using a daily streamflow record. We applied the model to the Minnesota River Basin, which has experienced significant changes in precipitation and runoff, increased sediment delivery, and decreasing mussel populations. Our model captures the general dynamics of the system and provides a better predictor of mussel populations than predictions based on geomorphic (e.g. upstream drainage area, slope) and hydraulic variables (e.g. 2-year recurrence interval peak streamflow, depth, width, cross sectional area, velocity, and Froude number) alone. To highlight the utility of our model, we tested possible scenarios that illustrate (1) how climate and land-use change may undermine the resilience of mussel populations and (2) how management efforts can allow mussel populations to recover.

  20. An ecologically relevant guinea pig model of fetal behavior

    PubMed Central

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

    2015-01-01

    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 multi-colored Hartley males were observed longitudinally without restraint using noninvasive ultrasound at weekly intervals across the 10 week gestation. To insure 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

  1. A review and synthesis of late Pleistocene extinction modeling: progress delayed by mismatches between ecological realism, interpretation, and methodological transparency.

    PubMed

    Yule, Jeffrey V; Fournier, Robert J; Jensen, Christopher X J; Yang, Jinyan

    2014-06-01

    Late Pleistocene extinctions occurred globally over a period of about 50,000 years, primarily affecting mammals of > or = 44 kg body mass (i.e., megafauna) first in Australia, continuing in Eurasia and, finally, in the Americas. Polarized debate about the cause(s) of the extinctions centers on the role of climate change and anthropogenic factors (especially hunting). Since the late 1960s, investigators have developed mathematical models to simulate the ecological interactions that might have contributed to the extinctions. Here, we provide an overview of the various methodologies used and conclusions reached in the modeling literature, addressing both the strengths and weaknesses of modeling as an explanatory tool. Although late Pleistocene extinction models now provide a solid foundation for viable future work, we conclude, first, that single models offer less compelling support for their respective explanatory hypotheses than many realize; second, that disparities in methodology (both in terms of model parameterization and design) prevent meaningful comparison between models and, more generally, progress from model to model in increasing our understanding of these extinctions; and third, that recent models have been presented and possibly developed without sufficient regard for the transparency of design that facilitates scientific progress. PMID:24984323

  2. Simulation Modeling of Software Development Processes

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

    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.

  3. Incorporation of RAM techniques into simulation modeling

    NASA Astrophysics Data System (ADS)

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

    1995-01-01

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

  4. Analyzing Strategic Business Rules through Simulation Modeling

    NASA Astrophysics Data System (ADS)

    Orta, Elena; Ruiz, Mercedes; Toro, Miguel

    Service Oriented Architecture (SOA) holds promise for business agility since it allows business process to change to meet new customer demands or market needs without causing a cascade effect of changes in the underlying IT systems. Business rules are the instrument chosen to help business and IT to collaborate. In this paper, we propose the utilization of simulation models to model and simulate strategic business rules that are then disaggregated at different levels of an SOA architecture. Our proposal is aimed to help find a good configuration for strategic business objectives and IT parameters. The paper includes a case study where a simulation model is built to help business decision-making in a context where finding a good configuration for different business parameters and performance is too complex to analyze by trial and error.

  5. Using structural equation modeling to investigate relationships among ecological variables

    USGS Publications Warehouse

    Malaeb, Z.A.; Kevin, Summers J.; Pugesek, B.H.

    2000-01-01

    Structural equation modeling is an advanced multivariate statistical process with which a researcher can construct theoretical concepts, test their measurement reliability, hypothesize and test a theory about their relationships, take into account measurement errors, and consider both direct and indirect effects of variables on one another. Latent variables are theoretical concepts that unite phenomena under a single term, e.g., ecosystem health, environmental condition, and pollution (Bollen, 1989). Latent variables are not measured directly but can be expressed in terms of one or more directly measurable variables called indicators. For some researchers, defining, constructing, and examining the validity of latent variables may be the end task of itself. For others, testing hypothesized relationships of latent variables may be of interest. We analyzed the correlation matrix of eleven environmental variables from the U.S. Environmental Protection Agency's (USEPA) Environmental Monitoring and Assessment Program for Estuaries (EMAP-E) using methods of structural equation modeling. We hypothesized and tested a conceptual model to characterize the interdependencies between four latent variables-sediment contamination, natural variability, biodiversity, and growth potential. In particular, we were interested in measuring the direct, indirect, and total effects of sediment contamination and natural variability on biodiversity and growth potential. The model fit the data well and accounted for 81% of the variability in biodiversity and 69% of the variability in growth potential. It revealed a positive total effect of natural variability on growth potential that otherwise would have been judged negative had we not considered indirect effects. That is, natural variability had a negative direct effect on growth potential of magnitude -0.3251 and a positive indirect effect mediated through biodiversity of magnitude 0.4509, yielding a net positive total effect of 0

  6. Distributed earth model/orbiter simulation

    NASA Technical Reports Server (NTRS)

    Geisler, Erik; Mcclanahan, Scott; Smith, Gary

    1989-01-01

    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.

  7. Common modeling system for digital simulation

    NASA Technical Reports Server (NTRS)

    Painter, Rick

    1994-01-01

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

  8. A coupled geomorphic and ecological model of tidal marsh evolution.

    PubMed

    Kirwan, Matthew L; Murray, A Brad

    2007-04-10

    The evolution of tidal marsh platforms and interwoven channel networks cannot be addressed without treating the two-way interactions that link biological and physical processes. We have developed a 3D model of tidal marsh accretion and channel network development that couples physical sediment transport processes with vegetation biomass productivity. Tidal flow tends to cause erosion, whereas vegetation biomass, a function of bed surface depth below high tide, influences the rate of sediment deposition and slope-driven transport processes such as creek bank slumping. With a steady, moderate rise in sea level, the model builds a marsh platform and channel network with accretion rates everywhere equal to the rate of sea-level rise, meaning water depths and biological productivity remain temporally constant. An increase in the rate of sea-level rise, or a reduction in sediment supply, causes marsh-surface depths, biomass productivity, and deposition rates to increase while simultaneously causing the channel network to expand. Vegetation on the marsh platform can promote a metastable equilibrium where the platform maintains elevation relative to a rapidly rising sea level, although disturbance to vegetation could cause irreversible loss of marsh habitat. PMID:17389384

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

    NASA Technical Reports Server (NTRS)

    Kirlik, Alex

    1991-01-01

    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.

  10. Wave modelling as a proxy for seagrass ecological modelling: Comparing fetch and process-based predictions for a bay and reef lagoon

    NASA Astrophysics Data System (ADS)

    Callaghan, David P.; Leon, Javier X.; Saunders, Megan I.

    2015-02-01

    The distribution, abundance, behaviour, and morphology of marine species is affected by spatial variability in the wave environment. Maps of wave metrics (e.g. significant wave height Hs, peak energy wave period Tp, and benthic wave orbital velocity URMS) are therefore useful for predictive ecological models of marine species and ecosystems. A number of techniques are available to generate maps of wave metrics, with varying levels of complexity in terms of input data requirements, operator knowledge, and computation time. Relatively simple "fetch-based" models are generated using geographic information system (GIS) layers of bathymetry and dominant wind speed and direction. More complex, but computationally expensive, "process-based" models are generated using numerical models such as the Simulating Waves Nearshore (SWAN) model. We generated maps of wave metrics based on both fetch-based and process-based models and asked whether predictive performance in models of benthic marine habitats differed. Predictive models of seagrass distribution for Moreton Bay, Southeast Queensland, and Lizard Island, Great Barrier Reef, Australia, were generated using maps based on each type of wave model. For Lizard Island, performance of the process-based wave maps was significantly better for describing the presence of seagrass, based on Hs, Tp, and URMS. Conversely, for the predictive model of seagrass in Moreton Bay, based on benthic light availability and Hs, there was no difference in performance using the maps of the different wave metrics. For predictive models where wave metrics are the dominant factor determining ecological processes it is recommended that process-based models be used. Our results suggest that for models where wave metrics provide secondarily useful information, either fetch- or process-based models may be equally useful.

  11. Battery thermal models for hybrid vehicle simulations

    NASA Astrophysics Data System (ADS)

    Pesaran, Ahmad A.

    This paper summarizes battery thermal modeling capabilities for: (1) an advanced vehicle simulator (ADVISOR); and (2) battery module and pack thermal design. The National Renewable Energy Laboratory's (NREL's) ADVISOR is developed in the Matlab/Simulink environment. There are several battery models in ADVISOR for various chemistry types. Each one of these models requires a thermal model to predict the temperature change that could affect battery performance parameters, such as resistance, capacity and state of charges. A lumped capacitance battery thermal model in the Matlab/Simulink environment was developed that included the ADVISOR battery performance models. For thermal evaluation and design of battery modules and packs, NREL has been using various computer aided engineering tools including commercial finite element analysis software. This paper will discuss the thermal ADVISOR battery model and its results, along with the results of finite element modeling that were presented at the workshop on "Development of Advanced Battery Engineering Models" in August 2001.

  12. Modeling surgical skill learning with cognitive simulation.

    PubMed

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

    2011-01-01

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

  13. An evolutionary ecological perspective on demographic transitions: modeling multiple currencies.

    PubMed

    Low, Bobbi S; Simon, Carl P; Anderson, Kermyt G

    2002-01-01

    Life history theory postulates tradeoffs of current versus future reproduction; today women face evolutionarily novel versions of these tradeoffs. Optimal age at first birth is the result of tradeoffs in fertility and mortality; ceteris paribus, early reproduction is advantageous. Yet modern women in developed nations experience relatively late first births; they appear to be trading off socioeconomic status and the paths to raised SES, education and work, against early fertility. Here, [1] using delineating parameter values drawn from data in the literature, we model these tradeoffs to determine how much socioeconomic advantage will compensate for delayed first births and lower lifetime fertility; and [2] we examine the effects of work and education on women's lifetime and age-specific fertility using data from seven cohorts in the Panel Study of Income Dynamics (PSID). PMID:11891931

  14. Microbial ecology-based methods to characterize the bacterial communities of non-model insects.

    PubMed

    Prosdocimi, Erica M; Mapelli, Francesca; Gonella, Elena; Borin, Sara; Crotti, Elena

    2015-12-01

    Among the animals of the Kingdom Animalia, insects are unparalleled for their widespread diffusion, diversity and number of occupied ecological niches. In recent years they have raised researcher interest not only because of their importance as human and agricultural pests, disease vectors and as useful breeding species (e.g. honeybee and silkworm), but also because of their suitability as animal models. It is now fully recognized that microorganisms form symbiotic relationships with insects, influencing their survival, fitness, development, mating habits and the immune system and other aspects of the biology and ecology of the insect host. Thus, any research aimed at deepening the knowledge of any given insect species (perhaps species of applied interest or species emerging as novel pests or vectors) must consider the characterization of the associated microbiome. The present review critically examines the microbiology and molecular ecology techniques that can be applied to the taxonomical and functional analysis of the microbiome of non-model insects. Our goal is to provide an overview of current approaches and methods addressing the ecology and functions of microorganisms and microbiomes associated with insects. Our focus is on operational details, aiming to provide a concise guide to currently available advanced techniques, in an effort to extend insect microbiome research beyond simple descriptions of microbial communities. PMID:26476138

  15. Ecological Interventionist Causal Models in Psychosis: Targeting Psychological Mechanisms in Daily Life.

    PubMed

    Reininghaus, Ulrich; Depp, Colin A; Myin-Germeys, Inez

    2016-03-01

    Integrated models of psychotic disorders have posited a number of putative psychological mechanisms that may contribute to the development of psychotic symptoms, but it is only recently that a modest amount of experience sampling research has provided evidence on their role in daily life, outside the research laboratory. A number of methodological challenges remain in evaluating specificity of potential causal links between a given psychological mechanism and psychosis outcomes in a systematic fashion, capitalizing on longitudinal data to investigate temporal ordering. In this article, we argue for testing ecological interventionist causal models that draw on real world and real-time delivered, ecological momentary interventions for generating evidence on several causal criteria (association, time order, and direction/sole plausibility) under real-world conditions, while maximizing generalizability to social contexts and experiences in heterogeneous populations. Specifically, this approach tests whether ecological momentary interventions can (1) modify a putative mechanism and (2) produce changes in the mechanism that lead to sustainable changes in intended psychosis outcomes in individuals' daily lives. Future research using this approach will provide translational evidence on the active ingredients of mobile health and in-person interventions that promote sustained effectiveness of ecological momentary interventions and, thereby, contribute to ongoing efforts that seek to enhance effectiveness of psychological interventions under real-world conditions. PMID:26707864

  16. Ecological risk assessment of water environment for Luanhe River Basin based on relative risk model.

    PubMed

    Liu, Jingling; Chen, Qiuying; Li, Yongli

    2010-11-01

    The relative risk model (RRM) was applied in regional ecological risk assessments successfully. In this study, the RRM was developed through increasing the data of risk source and introducing the source-stressor-habitat exposure filter (SSH), the endpoint-habitat exposure filter (EH) and the stressor-endpoint effect filter (SE) to reflect the meaning of exposure and effect more explicit. Water environment which include water quality, water quantity and aquatic ecosystems was selected as the ecological risk assessment endpoints. The Luanhe River Basin located in the North China was selected as model case. The results showed that there were three low risk regions, one medium risk region and two high risk regions in the Luanhe River Basin. The results also indicated habitat destruction was the largest stressor with the risk scores as high as 11.87 for the Luanhe water environment, the second was oxygen consuming organic pollutants (9.28) and the third was nutrients (7.78). So these three stressors were the main influencing factors of the ecological pressure in the study area. Furthermore, animal husbandry was the biggest source with the risk scores as high as 20.38, the second was domestic sewage (14.00), and the third was polluting industry (9.96). For habitats, waters and farmland were enduring the bigger pressure and should be taken considerable attention. Water deterioration and ecological service values damaged were facing the biggest risk pressure, and secondly was biodiversity decreased and landscape fragmentation. PMID:20683654

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

    USGS Publications Warehouse

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

    2010-01-01

    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.

  18. How well do climate models simulate precipitation?

    NASA Astrophysics Data System (ADS)

    Schaller, Nathalie; Mahlstein, Irina; Knutti, Reto; Cermak, Jan

    2010-05-01

    This study compares three different methods to evaluate the ability of Atmosphere Ocean General Circulation Models (AOGCMs) to simulate precipitation. Currently, AOGCMs are the most powerful tool to investigate the future climate but how to evaluate them is a relatively new research field. Thus, no standardized metric for defining a climate model's skill has been defined so far. The common way to proceed is to evaluate the model simulations against observations using statistical measures. However, precipitation is highly variable on both the spatial and temporal scales. We therefore suspect that metrics representing regional features of the modelled precipitation response to climate change are more suitable to identify the good models than statistical measures defined on a global scale. Here, we compare three different ways of ranking the climate models: a) biases in a broad range of climate variables, b) only biases in global precipitation and c) regional features of modelled precipitation in areas where future changes are expected to be pronounced. Surprisingly, the multimodel mean performs only average for the feature-based ranking, while it outperforms all single models in the two bias-based rankings. In the feature-based ranking, the models performing best can be different for each region or zonal band considered and identifying them each time newly depending on the purpose may allow for more reliable projections. Further, this study reveals that many models have similar biases and that the observation datasets are often located at one end of the model range. Our results suggest that weighting the models according to their ability to simulate the present climate might lead to more reliable projections than the "one model, one vote" approach that has been favored so far.

  19. Ion selective transistor modelling for behavioural simulations.

    PubMed

    Daniel, M; Janicki, M; Wroblewski, W; Dybko, A; Brzozka, Z; Napieralski, A

    2004-01-01

    Computer aided design and simulation of complex silicon microsystems oriented for environment monitoring requires efficient and accurate models of ion selective sensors, compatible with the existing behavioural simulators. This paper concerns sensors based on the back-side contact Ion Sensitive Field Effect Transistors (ISFETs). The ISFETs with silicon nitride gate are sensitive to hydrogen ion concentration. When the transistor gate is additionally covered with a special ion selective membrane, selectivity to other than hydrogen ions can be achieved. Such sensors are especially suitable for flow analysis of solutions containing various ions. The problem of ion selective sensor modelling is illustrated here on a practical example of an ammonium sensitive membrane. The membrane is investigated in the presence of some interfering ions and appropriate selectivity coefficients are determined. Then, the model of the whole sensor is created and used in subsequent electrical simulations. Providing that appropriate selectivity coefficients are known, the proposed model is applicable for any membrane, and can be straightforwardly implemented for behavioural simulation of water monitoring microsystems. The model has been already applied in a real on-line water pollution monitoring system for detection of various contaminants. PMID:15685987

  20. Ecological Acclimation and Hydrologic Response: Problem Complexity and Modeling Challenges

    NASA Astrophysics Data System (ADS)

    Kumar, P.; Srinivasan, V.; Le, P. V. V.; Drewry, D.

    2012-04-01

    Elevated CO2 in the atmosphere leads to a number of acclimatory responses in different vegetation types. These may be characterized as structural such as vegetation height or foliage density, ecophysiological such as reduction in stomatal conductance, and biochemical such as photosynthetic down-regulation. Furthermore, the allocation of assimilated carbon to different vegetation parts such as leaves, roots, stem and seeds is also altered such that empirical allometric relations are no longer valid. The extent and nature of these acclimatory responses vary between C3 and C4 vegetation and across species. These acclimatory responses have significant impact on hydrologic fluxes both pertaining to water and energy with the possibility of large-scale hydrologic influence. Capturing the pathways of acclimatory response to provide accurate ecohydrologic response predictions requires incorporating subtle relationships that are accentuated under elevated CO2. The talk will discuss the challenges of modeling these as well as applications to soybean, maize and bioenergy crops such as switchgrass and miscanthus.

  1. Damage modeling for Taylor impact simulations

    NASA Astrophysics Data System (ADS)

    Anderson, C. E., Jr.; Chocron, I. S.; Nicholls, A. E.

    2006-08-01

    G. I. Taylor showed that dynamic material properties could be deduced from the impact of a projectile against a rigid boundary. The Taylor anvil test became very useful with the advent of numerical simulations and has been used to infer and/or to validate material constitutive constants. A new experimental facility has been developed to conduct Taylor anvil impacts to support validation of constitutive constants used in simulations. Typically, numerical simulations are conducted assuming 2-D cylindrical symmetry, but such computations cannot hope to capture the damage observed in higher velocity experiments. A computational study was initiated to examine the ability to simulate damage and subsequent deformation of the Taylor specimens. Three-dimensional simulations, using the Johnson-Cook damage model, were conducted with the nonlinear Eulerian wavecode CTH. The results of the simulations are compared to experimental deformations of 6061-T6 aluminum specimens as a function of impact velocity, and conclusions regarding the ability to simulate fracture and reproduce the observed deformations are summarized.

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

    PubMed Central

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

    2014-01-01

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

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

    USGS Publications Warehouse

    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

    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).

  4. Observation simulation experiments with regional prediction models

    NASA Technical Reports Server (NTRS)

    Diak, George; Perkey, Donald J.; Kalb, Michael; Robertson, Franklin R.; Jedlovec, Gary

    1990-01-01

    Research efforts in FY 1990 included studies employing regional scale numerical models as aids in evaluating potential contributions of specific satellite observing systems (current and future) to numerical prediction. One study involves Observing System Simulation Experiments (OSSEs) which mimic operational initialization/forecast cycles but incorporate simulated Advanced Microwave Sounding Unit (AMSU) radiances as input data. The objective of this and related studies is to anticipate the potential value of data from these satellite systems, and develop applications of remotely sensed data for the benefit of short range forecasts. Techniques are also being used that rely on numerical model-based synthetic satellite radiances to interpret the information content of various types of remotely sensed image and sounding products. With this approach, evolution of simulated channel radiance image features can be directly interpreted in terms of the atmospheric dynamical processes depicted by a model. Progress is being made in a study using the internal consistency of a regional prediction model to simplify the assessment of forced diabatic heating and moisture initialization in reducing model spinup times. Techniques for model initialization are being examined, with focus on implications for potential applications of remote microwave observations, including AMSU and Special Sensor Microwave Imager (SSM/I), in shortening model spinup time for regional prediction.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  6. Modeling and Simulation of Nuclear Fuel Materials

    SciTech Connect

    Devanathan, Ram; Van Brutzel, Laurent; Tikare, Veena; Bartel, Timothy; Besmann, Theodore M; Stan, Marius; Van Uffelen, Paul

    2010-01-01

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

  7. Modeling and Simulation of Nuclear Fuel Materials

    SciTech Connect

    Devanathan, Ramaswami; Van Brutzel, Laurent; Chartier, Alan; Gueneau, Christine; Mattsson, Ann E.; Tikare, Veena; Bartel, Timothy; Besmann, T. M.; Stan, Marius; Van Uffelen, Paul

    2010-10-01

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

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

    NASA Astrophysics Data System (ADS)

    Stefanova, L. B.

    2013-12-01

    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

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

    ERIC Educational Resources Information Center

    Shubik, Martin; Brewer, Garry D.

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

  10. Center for Advanced Modeling and Simulation Intern

    SciTech Connect

    Gertman, Vanessa

    2010-01-01

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

  11. Love Kills:. Simulations in Penna Ageing Model

    NASA Astrophysics Data System (ADS)

    Stauffer, Dietrich; Cebrat, Stanisław; Penna, T. J. P.; Sousa, A. O.

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

  12. Teaching Environmental Systems Modelling Using Computer Simulation.

    ERIC Educational Resources Information Center

    Moffatt, Ian

    1986-01-01

    A computer modeling course in environmental systems and dynamics is presented. The course teaches senior undergraduates to analyze a system of interest, construct a system flow chart, and write computer programs to simulate real world environmental processes. An example is presented along with a course evaluation, figures, tables, and references.…

  13. Center for Advanced Modeling and Simulation Intern

    ScienceCinema

    Gertman, Vanessa

    2013-05-28

    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.

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

    PubMed

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

    2008-01-01

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

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

    PubMed

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

    2012-06-01

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

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

    PubMed

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

    2014-01-01

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

  17. Do Ecological Niche Models Accurately Identify Climatic Determinants of Species Ranges?

    PubMed

    Searcy, Christopher A; Shaffer, H Bradley

    2016-04-01

    Defining species' niches is central to understanding their distributions and is thus fundamental to basic ecology and climate change projections. Ecological niche models (ENMs) are a key component of making accurate projections and include descriptions of the niche in terms of both response curves and rankings of variable importance. In this study, we evaluate Maxent's ranking of environmental variables based on their importance in delimiting species' range boundaries by asking whether these same variables also govern annual recruitment based on long-term demographic studies. We found that Maxent-based assessments of variable importance in setting range boundaries in the California tiger salamander (Ambystoma californiense; CTS) correlate very well with how important those variables are in governing ongoing recruitment of CTS at the population level. This strong correlation suggests that Maxent's ranking of variable importance captures biologically realistic assessments of factors governing population persistence. However, this result holds only when Maxent models are built using best-practice procedures and variables are ranked based on permutation importance. Our study highlights the need for building high-quality niche models and provides encouraging evidence that when such models are built, they can reflect important aspects of a species' ecology. PMID:27028071

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

    PubMed Central

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

    2013-01-01

    Most of our knowledge about avian haemosporidian parasites comes from the Hawaiian archipelago, where recently introduced Plasmodiumrelictum has contributed to the extinction of many endemic avian species. While the ecology of invasive malaria is reasonably understood, the ecology of endemic haemosporidian infection in mainland systems is poorly understood, even though it is the rule rather than the exception. We develop a mathematical model to explore and identify the ecological factors that most influence transmission of the common avian parasite, Leucocytozoonfringillinarum (Apicomplexa). The model was parameterized from White-crowned Sparrow (Zonotrichialeucophrys) and S. silvestre / craigi black fly populations breeding in an alpine ecosystem. We identify and examine the importance of altricial nestlings, the seasonal relapse of infected birds for parasite persistence across breeding seasons, and potential impacts of seasonal changes in black fly emergence on parasite prevalence in a high elevation temperate system. We also use the model to identify and estimate the parameters most influencing transmission dynamics. Our analysis found that relapse of adult birds and young of the year birds were crucial for parasite persistence across multiple seasons. However, distinguishing between nude nestlings and feathered young of the year was unnecessary. Finally, due to model sensitivity to many black fly parameters, parasite prevalence and sparrow recruitment may be most affected by seasonal changes in environmental temperature driving shifts in black fly emergence and gonotrophic cycles. PMID:24073288

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

    SciTech Connect

    Munns, W.R. Jr.; Nacci, D.E.; Walker, H.A.; Johnston, R.K.

    1994-12-31

    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.

  20. Adaptive System Modeling for Spacecraft Simulation

    NASA Technical Reports Server (NTRS)

    Thomas, Justin

    2011-01-01

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

  1. Twitter's tweet method modelling and simulation

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Wade, Rose C.

    1989-01-01

    The NASA Controlled Ecological Life Support System (CELSS) Program is involved in developing a biogenerative life support system that will supply food, air, and water to space crews on long-duration missions. An important part of this effort is in development of the knowledge and technological capability of producing and processing foods to provide optimal diets for space crews. This involves such interrelated factors as determination of the diet, based on knowledge of nutrient needs of humans and adjustments in those needs that may be required as a result of the conditions of long-duration space flight; determination of the optimal mixture of crops required to provide nutrients at levels that are sufficient but not excessive or toxic; and consideration of the critical issues of spacecraft space and power limitations, which impose a phytomass minimization requirement. The complex interactions among these factors are examined with the goal of supplying a diet that will satisfy human needs while minimizing the total phytomass requirement. The approach taken was to collect plant nutritional composition and phytomass production data, identify human nutritional needs and estimate the adjustments to the nutrient requirements likely to result from space flight, and then to generate mathematical models from these data.

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

    PubMed

    Campbell, Rebecca; Dworkin, Emily; Cabral, Giannina

    2009-07-01

    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

  4. Numerical simulations and modeling of turbulent combustion

    NASA Astrophysics Data System (ADS)

    Cuenot, B.

    Turbulent combustion is the basic physical phenomenon responsible for efficient energy release by any internal combustion engine. However it is accompanied by other undesirable phenomena such as noise, pollutant species emission or damaging instabilities that may even lead to the system desctruction. It is then crucial to control this phenomenon, to understand all its mecanisms and to master it in industrial systems. For long time turbulent combustion has been explored only through theory and experiment. But the rapid increase of computers power during the last years has allowed an important development of numerical simulation, that has become today an essential tool for research and technical design. Direct numerical simulation has then allowed to rapidly progress in the knowledge of turbulent flame structures, leading to new modelisations for steady averaged simulations. Recently large eddy simulation has made a new step forward by refining the description of complex and unsteady flames. The main problem that arises when performing numerical simulation of turbulent combustion is linked to the description of the flame front. Being very thin, it can not however be reduced to a simple interface as it is the location of intense chemical transformation and of strong variations of thermodynamical quantities. Capturing the internal structure of a zone with a thickness of the order of 0.1 mm in a computation with a mesh step 10 times larger being impossible, it is necessary to model the turbulent flame. Models depend on the chemical structure of the flame, on the ambiant turbulence, on the combustion regime (flamelets, distributed combustion, etc.) and on the reactants injection mode (premixed or not). One finds then a large class of models, from the most simple algebraic model with a one-step chemical kinetics, to the most complex model involving probablity density functions, cross-correlations and multiple-step or fully complex chemical kinetics.

  5. Advances in NLTE modeling for integrated simulations

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

    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, Δ 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.

  6. Computational Spectrum of Agent Model Simulation

    SciTech Connect

    Perumalla, Kalyan S

    2010-01-01

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

  7. Upscaling aquatic ecology: Pairing modern analytics with Big Data to simulate 2500 U.S. lakes

    NASA Astrophysics Data System (ADS)

    Read, J. S.; Winslow, L.; Hansen, G.; Van Den Hoek, J.; Markfort, C. D.; Booth, N.

    2013-12-01

    Lakes are increasingly recognized as relevant engines in global processes, as recent estimates of the number of lakes and their contribution to biogeochemical cycles greatly exceed estimates from earlier assessments. Currently, our understanding of the diversity of physical controls on lake ecosystems is lacking, in part due to geographically limited observational campaigns and a failure to integrate Big Data products and informatics into modern limnological science practices. Momentum towards the interoperability of cyber-infrastructure in the fields of hydrology, climatology, remote sensing, and the geosciences has provided timely access to the pursuit of research aimed at upscaling our knowledge of the drivers of aquatic ecosystems. Here we share details of an open-source, standards-based data manipulation framework and one-dimensional model that were used to simulate water temperature dynamics for thousands of individual lakes. In addition to the automated scaling of gridded meteorological driver data, we integrated satellite estimates of water clarity and surrounding canopy heights in order to parameterize important lake-specific characteristics that influence lake physics. These methods keep terabyte-scale data off of the desktop through the use of web processing services, which performed many of our data-rich and computationally intensive tasks. We highlight results from a regional test-bed (the state of Wisconsin), as well as discuss opportunities for aquatic ecologists to leverage future pairings between Big Data and web-informatics. Supporting datasets include satellite imagery, space and airborne LIDAR, gridded climate reanalysis data, hydrography inventories, and citizen scientist measurements of water temperature; all components of the successful modeling of daily water temperature profiles for 2,500 lakes during 1979-2011. These results are being used to explain the long-term climate component of trends in the populations of two staples of the

  8. Conceptualizing Ecology: A Learning Cycle Approach.

    ERIC Educational Resources Information Center

    Lauer, Thomas E.

    2003-01-01

    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)

  9. Modelling the ecological consequences of whole tree harvest for bioenergy production

    NASA Astrophysics Data System (ADS)

    Skår, Silje; Lange, Holger; Sogn, Trine

    2013-04-01

    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

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

    USGS Publications Warehouse

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

    2015-01-01

    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.

  11. Robust three-body water simulation model

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

    The most common potentials used in classical simulations of liquid water assume a pairwise additive form. Although these models have been very successful in reproducing many properties of liquid water at ambient conditions, none is able to describe accurately water throughout its complicated phase diagram. The primary reason for this is the neglect of many-body interactions. To this end, a simulation model with explicit three-body interactions was introduced recently [R. Kumar and J. L. Skinner, J. Phys. Chem. B 112, 8311 (2008), 10.1021/jp8009468]. This model was parameterized to fit the experimental O-O radial distribution function and diffusion constant. Herein we reparameterize the model, fitting to a wider range of experimental properties (diffusion constant, rotational correlation time, density for the liquid, liquid/vapor surface tension, melting point, and the ice Ih density). The robustness of the model is then verified by comparing simulation to experiment for a number of other quantities (enthalpy of vaporization, dielectric constant, Debye relaxation time, temperature of maximum density, and the temperature-dependent second and third virial coefficients), with good agreement.

  12. Modeling of protein loops by simulated annealing.

    PubMed Central

    Collura, V.; Higo, J.; Garnier, J.

    1993-01-01

    A method is presented to model loops of protein to be used in homology modeling of proteins. This method employs the ESAP program of Higo et al. (Higo, J., Collura, V., & Garnier, J., 1992, Biopolymers 32, 33-43) and is based on a fast Monte Carlo simulation and a simulated annealing algorithm. The method is tested on different loops or peptide segments from immunoglobulin, bovine pancreatic trypsin inhibitor, and bovine trypsin. The predicted structure is obtained from the ensemble average of the coordinates of the Monte Carlo simulation at 300 K, which exhibits the lowest internal energy. The starting conformation of the loop prior to modeling is chosen to be completely extended, and a closing harmonic potential is applied to N, CA, C, and O atoms of the terminal residues. A rigid geometry potential of Robson and Platt (1986, J. Mol. Biol. 188, 259-281) with a united atom representation is used. This we demonstrate to yield a loop structure with good hydrogen bonding and torsion angles in the allowed regions of the Ramachandran map. The average accuracy of the modeling evaluated on the eight modeled loops is 1 A root mean square deviation (rmsd) for the backbone atoms and 2.3 A rmsd for all heavy atoms. PMID:8401234

  13. Fault diagnosis based on continuous simulation models

    NASA Technical Reports Server (NTRS)

    Feyock, Stefan

    1987-01-01

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

  14. Electronic continuum model for molecular dynamics simulations.

    PubMed

    Leontyev, I V; Stuchebrukhov, A A

    2009-02-28

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

  15. Flight Simulation Model Exchange. Volume 2; Appendices

    NASA Technical Reports Server (NTRS)

    Murri, Daniel G.; Jackson, E. Bruce

    2011-01-01

    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.

  16. Flight Simulation Model Exchange. Volume 1

    NASA Technical Reports Server (NTRS)

    Murri, Daniel G.; Jackson, E. Bruce

    2011-01-01

    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.

  17. Atmospheric Modeling And Sensor Simulation (AMASS) study

    NASA Technical Reports Server (NTRS)

    Parker, K. G.

    1984-01-01

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

  18. Computational model for protein unfolding simulation

    NASA Astrophysics Data System (ADS)

    Tian, Xu-Hong; Zheng, Ye-Han; Jiao, Xiong; Liu, Cai-Xing; Chang, Shan

    2011-06-01

    The protein folding problem is one of the fundamental and important questions in molecular biology. However, the all-atom molecular dynamics studies of protein folding and unfolding are still computationally expensive and severely limited by the time scale of simulation. In this paper, a simple and fast protein unfolding method is proposed based on the conformational stability analyses and structure modeling. In this method, two structure-based conditions are considered to identify the unstable regions of proteins during the unfolding processes. The protein unfolding trajectories are mimicked through iterative structure modeling according to conformational stability analyses. Two proteins, chymotrypsin inhibitor 2 (CI2) and α -spectrin SH3 domain (SH3) were simulated by this method. Their unfolding pathways are consistent with the previous molecular dynamics simulations. Furthermore, the transition states of the two proteins were identified in unfolding processes and the theoretical Φ values of these transition states showed significant correlations with the experimental data (the correlation coefficients are >0.8). The results indicate that this method is effective in studying protein unfolding. Moreover, we analyzed and discussed the influence of parameters on the unfolding simulation. This simple coarse-grained model may provide a general and fast approach for the mechanism studies of protein folding.

  19. Compressible homogeneous shear: Simulation and modeling

    NASA Technical Reports Server (NTRS)

    Sarkar, S.; Erlebacher, G.; Hussaini, M. Y.

    1992-01-01

    Compressibility effects were studied on turbulence by direct numerical simulation of homogeneous shear flow. A primary observation is that the growth of the turbulent kinetic energy decreases with increasing turbulent Mach number. The sinks provided by compressible dissipation and the pressure dilatation, along with reduced Reynolds shear stress, are shown to contribute to the reduced growth of kinetic energy. Models are proposed for these dilatational terms and verified by direct comparison with the simulations. The differences between the incompressible and compressible fields are brought out by the examination of spectra, statistical moments, and structure of the rate of strain tensor.

  20. Blast furnace on-line simulation model

    NASA Astrophysics Data System (ADS)

    Saxén, Henrik

    1990-10-01

    A mathematical model of the ironmaking blast furnace (BF) is presented. The model describes the steady-state operation of the furnace in one spatial dimension using real process data sampled at the steelworks. The measurement data are reconciled by an interface routine which yields boundary conditions obeying the conservation laws of atoms and energy. The simulation model, which provides a picture of the internal conditions of the BF, can be used to evaluate the current state of the process and to predict the effect of operating actions on the performance of the furnace.

  1. An empirical model of the Baltic Sea reveals the importance of social dynamics for ecological regime shifts.

    PubMed

    Lade, Steven J; Niiranen, Susa; Hentati-Sundberg, Jonas; Blenckner, Thorsten; Boonstra, Wiebren J; Orach, Kirill; Quaas, Martin F; Österblom, Henrik; Schlüter, Maja

    2015-09-01

    Regime shifts triggered by human activities and environmental changes have led to significant ecological and socioeconomic consequences in marine and terrestrial ecosystems worldwide. Ecological processes and feedbacks associated with regime shifts have received considerable attention, but human individual and collective behavior is rarely treated as an integrated component of such shifts. Here, we used generalized modeling to develop a coupled social-ecological model that integrated rich social and ecological data to investigate the role of social dynamics in the 1980s Baltic Sea cod boom and collapse. We showed that psychological, economic, and regulatory aspects of fisher decision making, in addition to ecological interactions, contributed both to the temporary persistence of the cod boom and to its subsequent collapse. These features of the social-ecological system also would have limited the effectiveness of stronger fishery regulations. Our results provide quantitative, empirical evidence that incorporating social dynamics into models of natural resources is critical for understanding how resources can be managed sustainably. We also show that generalized modeling, which is well-suited to collaborative model development and does not require detailed specification of causal relationships between system variables, can help tackle the complexities involved in creating and analyzing social-ecological models. PMID:26283344

  2. An empirical model of the Baltic Sea reveals the importance of social dynamics for ecological regime shifts

    PubMed Central

    Lade, Steven J.; Niiranen, Susa; Hentati-Sundberg, Jonas; Blenckner, Thorsten; Boonstra, Wiebren J.; Orach, Kirill; Quaas, Martin F.; Österblom, Henrik; Schlüter, Maja

    2015-01-01

    Regime shifts triggered by human activities and environmental changes have led to significant ecological and socioeconomic consequences in marine and terrestrial ecosystems worldwide. Ecological processes and feedbacks associated with regime shifts have received considerable attention, but human individual and collective behavior is rarely treated as an integrated component of such shifts. Here, we used generalized modeling to develop a coupled social–ecological model that integrated rich social and ecological data to investigate the role of social dynamics in the 1980s Baltic Sea cod boom and collapse. We showed that psychological, economic, and regulatory aspects of fisher decision making, in addition to ecological interactions, contributed both to the temporary persistence of the cod boom and to its subsequent collapse. These features of the social–ecological system also would have limited the effectiveness of stronger fishery regulations. Our results provide quantitative, empirical evidence that incorporating social dynamics into models of natural resources is critical for understanding how resources can be managed sustainably. We also show that generalized modeling, which is well-suited to collaborative model development and does not require detailed specification of causal relationships between system variables, can help tackle the complexities involved in creating and analyzing social–ecological models. PMID:26283344

  3. Development of stressor-response models for an ecological risk assessment case study

    SciTech Connect

    Nacci, D.E.; Munns, W.R.; Cayula, S.; Serbst, J.; Johnston, R.K.; Walker, H.A.

    1994-12-31

    An estuarine ecological risk assessment for the Portsmouth Naval Shipyard (Kittery, ME) is being conducted following the US EPA`s Framework for Ecological Risk Assessment (ERA). As part of the Analysis phase of the ERA, laboratory studies were conducted to develop stressor-response models for lead, the primary contaminant of concern. Thirty-day exposures to adult sea urchins, Arbacia punctulata, occurred via food or suspended sediment. Exposure media were amended with lead sulfate to 10--100 or 100--300 times uncontaminated levels for the Feeding or Sediment Experiments, respectively. The sea urchin experimental model was selected because it permitted the measurement of biological endpoints with significance at the population level (e.g., adult survival and reproduction success), including those used in standard marine bioassays (i.e., fertilization and larval development). Feeding Experiment treatments produced few effects. Sediment Experiment treatments resulted in reductions in survival, growth and reproductive output of exposed adults and were directly toxic to early lifestages. However, in uncontaminated sea water, gametes from Sediment Experiment adults fertilized and completed larval development normally. Data from these experimental systems will be used to produce models relating lead exposure to specific biological responses and, ultimately, ecological risk.

  4. GLAST Burst Monitor Instrument Simulation and Modeling

    SciTech Connect

    Hoover, A. S.; Kippen, R. M.; Wallace, M. S.; Pendleton, G. N.; Fishman, G. J.; Meegan, C. A.; Kouveliotou, C.; Wilson-Hodge, C. A.; Bhat, P. N.; Briggs, M. S.; Connaughton, V.; Paciesas, W. S.; Preece, R. D.

    2008-05-22

    The GLAST Burst Monitor (GBM) is designed to provide wide field of view observations of gamma-ray bursts and other fast transient sources in the energy range 10 keV to 30 MeV. The GBM is composed of several unshielded and uncollimated scintillation detectors (twelve NaI and two BGO) that are widely dispersed about the GLAST spacecraft. As a result, reconstructing source locations, energy spectra, and temporal properties from GBM data requires detailed knowledge of the detectors' response to both direct radiation as well as that scattered from the spacecraft and Earth's atmosphere. This full GBM instrument response will be captured in the form of a response function database that is derived from computer modeling and simulation. The simulation system is based on the GEANT4 Monte Carlo radiation transport simulation toolset.

  5. Facebook's personal page modelling and simulation

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    In this paper we will try to define the utility of Facebook's Personal Page marketing method. This tool that Facebook provides, is modelled and simulated using iThink in the context of a Facebook 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 model has been developed for a social media marketing agent/company, Facebook platform oriented and tested in real circumstances. This model is finalized through a number of revisions and iterators of the design, development, simulation, testing and evaluation processes. The validity and usefulness of this Facebook marketing model for the day-to-day decision making are authenticated by the management of the company organization. Facebook's Personal Page method can be adjusted, depending on the situation, in order to maximize the total profit of the company which is to bring new customers, keep the interest of the old customers and deliver traffic to its website.

  6. Optimisation Strategies for Modelling and Simulation

    NASA Astrophysics Data System (ADS)

    Louchet, Jean

    2007-12-01

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

  7. Towards Better Coupling of Hydrological Simulation Models

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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

  8. Theory, modeling and simulation: Annual report 1993

    SciTech Connect

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

    1994-07-01

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

  9. eShopper modeling and simulation

    NASA Astrophysics Data System (ADS)

    Petrushin, Valery A.

    2001-03-01

    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.

  10. 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...

  11. Simulating temperature-dependent ecological processes at the sub-continental scale: male gypsy moth flight phenology as an example

    NASA Astrophysics Data System (ADS)

    Régnière, J.; Sharov, Alexei

    We simulated male gypsy moth flight phenology for the location of 1371 weather stations east of 100° W longitude and north of 35° N latitude in North America. The output of these simulations, based on average weather conditions from 1961 to 1990, was submitted to two map-interpolation methods: multiple regression and universal kriging. Multiple regression was found to be as accurate as universal kriging and demands less computing power. A map of the date of peak male gypsy moth flight was generated by universal kriging. This map itself constitutes a useful pest-management planning tool; in addition, the map delineates the potential range of the gypsy moth based on its seasonality at the northern edge of its current distribution in eastern North America. The simulation and map-interpolation methods described in this paper thus constitute an interesting approach to the study and monitoring of the ecological impacts of climate change and shifts in land-use patterns at the sub-continental level.

  12. Modelling and simulation of virtual Mars scene

    NASA Astrophysics Data System (ADS)

    Sun, Si-liang; Chen, Ren; Sun, Li; Yan, Jie

    2011-08-01

    There is a limited cognition on human beings comprehend the universe. Aiming at the impending need of mars exploration in the near future, starting from the mars three-dimensional (3D) model, the mars texture which based on several reality pictures was drew and the Bump mapping technique was managed to enhance the realistic rendering. In order to improve the simulation fidelity, the composing of mars atmospheric was discussed and the reason caused atmospheric scattering was investigated, the scattering algorithm was studied and calculated as well. The reasons why "Red storm" that frequently appeared on mars were particularized, these factors inevitable brought on another celestial body appearance. To conquer this problem, two methods which depended on different position of view point (universe point and terrestrial point) were proposed: in previous way, the 3D model was divided into different meshes to simulate the storm effect and the formula algorithm that mesh could rotate with any axis was educed. From a certain extent the model guaranteed rendering result when looked at the mars (with "Red storm") in universe; in latter way, 3D mars terrain scene was build up according to the mars pictures downloaded on "Google Mars", particle system used to simulated the storm effect, then the Billboard technique was managed to finish the color emendation and rendering compensation. At the end, the star field simulation based on multiple texture blending was given. The result of experiment showed that these methods had not only given a substantial increase in fidelity, but also guaranteed real-time rendering. It can be widely used in simulation of space battlefield and exploration tasks.

  13. Pattern-oriented modelling: a 'multi-scope' for predictive systems ecology.

    PubMed

    Grimm, Volker; Railsback, Steven F

    2012-01-19

    Modern ecology recognizes that modelling systems across scales and at multiple levels-especially to link population and ecosystem dynamics to individual adaptive behaviour-is essential for making the science predictive. 'Pattern-oriented modelling' (POM) is a strategy for doing just this. POM is the multi-criteria design, selection and calibration of models of complex systems. POM starts with identifying a set of patterns observed at multiple scales and levels that characterize a system with respect to the particular problem being modelled; a model from which the patterns emerge should contain the right mechanisms to address the problem. These patterns are then used to (i) determine what scales, entities, variables and processes the model needs, (ii) test and select submodels to represent key low-level processes such as adaptive behaviour, and (iii) find useful parameter values during calibration. Patterns are already often used in these ways, but a mini-review of applications of POM confirms that making the selection and use of patterns more explicit and rigorous can facilitate the development of models with the right level of complexity to understand ecological systems and predict their response to novel conditions. PMID:22144392

  14. Simulation model of clastic sedimentary processes

    SciTech Connect

    Tetzlaff, D.M.

    1987-01-01

    This dissertation describes SEDSIM, a computer model that simulates erosion, transport, and deposition of clastic sediments by free-surface flow in natural environments. SEDSIM is deterministic and is applicable to sedimentary processes in rivers, deltas, continental shelves, submarine canyons, and turbidite fans. The model is used to perform experiments in clastic sedimentation. Computer experimentation is limited by computing power available, but is free from scaling problems associated with laboratory experiments. SEDSIM responds to information provided to it at the outset of a simulation experiment, including topography, subsurface configuration, physical parameters of fluid and sediment, and characteristics of sediment sources. Extensive computer graphics are incorporated in SEDSIM. The user can display the three-dimensional geometry of simulated deposits in the form of successions of contour maps, perspective diagrams, vector plots of current velocities, and vertical sections of any azimuth orientation. The sections show both sediment age and composition. SEDSIM works realistically with processes involving channel shifting and topographic changes. Example applications include simulation of an ancient submarine canyon carved into a Cretaceous sequence in the National Petroleum Reserve in Alaska, known mainly from seismic sections and a sequence of Tertiary age in the Golden Meadow oil field of Louisiana, known principally from well logs.

  15. Modeling Hydrology, Phosphorus and Ecology in the Hampshire Avon Catchment to Assess Alternative Strategies to Improve Water Quality

    NASA Astrophysics Data System (ADS)

    Jin, L.; Whitehead, P. G.; Crossman, J.

    2013-12-01

    Phosphorus (P) enrichment is a worldwide issue of fresh river systems that causes algae blooms, oxygen decline and eutrophication. Therefore, controlling the input of nutrients especially P into aquatic ecosystems is a crucial management focus across much of the world. For example, approximately 70% of water bodies in the Hampshire Avon catchment (UK) are considered not in a good ecological condition due to excess soluble reactive phosphorus (SRP) in the water. In this work, we explored the issues of diffuse and point source P pollution in the Hampshire Avon catchment using an integrated catchment model (INCA) and further we used the model to assess different management options for P reduction. A multi-branch, process based, dynamic water quality model (INCA-P) has been applied to the whole Hampshire Avon river system to simulate water fluxes, concentrations of total phosphorus (TP) and SRP, and ecology. The model has been used to assess impacts of both agricultural runoff and point sources from Waste Water Treatment Plants (WWTPs) on water quality. The results showed that agriculture contributes approximately 40% of the P load and point sources contribute the other 60%. A set of scenarios have been investigated to assess the impacts of alternative P reduction strategies and results suggest that a combined strategy of agricultural P reduction through either fertilizer reductions or better P management together with improved treatment at WWTPs would reduce the SRP concentrations in the river to acceptable levels to meet the European legislation e.g. Water Framework Directive requirements. A seasonal strategy for P reductions from WWTPs would achieve significant benefits at reduced cost.

  16. Consequence modeling using the fire dynamics simulator.

    PubMed

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

    2004-11-11

    The use of Computational Fluid Dynamics (CFD) and in particular Large Eddy Simulation (LES) codes to model fires provides an efficient tool for the prediction of large-scale effects that include plume characteristics, combustion product dispersion, and heat effects to adjacent objects. This paper illustrates the strengths of the Fire Dynamics Simulator (FDS), an LES code developed by the National Institute of Standards and Technology (NIST), through several small and large-scale validation runs and process safety applications. The paper presents two fire experiments--a small room fire and a large (15 m diameter) pool fire. The model results are compared to experimental data and demonstrate good agreement between the models and data. The validation work is then extended to demonstrate applicability to process safety concerns by detailing a model of a tank farm fire and a model of the ignition of a gaseous fuel in a confined space. In this simulation, a room was filled with propane, given time to disperse, and was then ignited. The model yields accurate results of the dispersion of the gas throughout the space. This information can be used to determine flammability and explosive limits in a space and can be used in subsequent models to determine the pressure and temperature waves that would result from an explosion. The model dispersion results were compared to an experiment performed by Factory Mutual. Using the above examples, this paper will demonstrate that FDS is ideally suited to build realistic models of process geometries in which large scale explosion and fire failure risks can be evaluated with several distinct advantages over more traditional CFD codes. Namely transient solutions to fire and explosion growth can be produced with less sophisticated hardware (lower cost) than needed for traditional CFD codes (PC type computer verses UNIX workstation) and can be solved for longer time histories (on the order of hundreds of seconds of computed time) with

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

    NASA Astrophysics Data System (ADS)

    Hagen, S. C.; Lewis, G.; Bartel, R.; Batten, B.; Huang, W.; Morris, J.; Slinn, D. N.; Sparks, J.; Walters, L.; Wang, D.; Weishampel, J.; Yeh, G.

    2010-12-01

    Sea level rise (SLR) has the potential to affect a variety of coastal habitats with a myriad of deleterious ecological effects and to overwhelm human settlements along the coast. SLR should be given serious consideration when more than half of the U.S. population lives within 50 miles of the coast. SLR effects will be felt along coastal beaches and in estuarine waters, with consequences to barrier islands, submerged aquatic vegetation beds, sand and mud flats, oyster reefs, and tidal and freshwater wetlands. Managers of these coastal resources must be aware of potential consequences of SLR and adjust their plans accordingly to protect and preserve the resources under their care. The Gulf Coast provides critical habitats for a majority of the commercially important species in the Gulf of Mexico, which depend on inshore waters for either permanent residence or nursery area. The ecosystem services provided by these coastal habitats are at risk from rising sea level. Our team will assess the risk to coasts and coastal habitats from SLR in a 5-year project. We will apply existing models of circulation and transport from the watershed to the sea. The ultimate prediction will be of sediment loadings to the estuary as a result of overland flow, shoreline and barrier island erosion, and salinity transport, all of which will be used to model the evolution of intertidal marshes (MEM II). Over the five-year course of our research we will be simulating hydrodynamics and transport for all three NERRS reserves, including: Apalachicola, Weeks Bay and Grand Bay. The project will result in products whereby managers will be able to assess marshes, oyster reefs, submerged aquatic vegetation, predict wetland stability and indentify restoration locations for marsh and oyster habitats. In addition, we will produce Decision Support tools that will enable managers to predict future coastal erosion rates for management-specified shorelines. Project outcomes will enable the management

  18. High-Fidelity Roadway Modeling and Simulation

    NASA Technical Reports Server (NTRS)

    Wang, Jie; Papelis, Yiannis; Shen, Yuzhong; Unal, Ozhan; Cetin, Mecit

    2010-01-01

    Roads are an essential feature in our daily lives. With the advances in computing technologies, 2D and 3D road models are employed in many applications, such as computer games and virtual environments. Traditional road models were generated by professional artists manually using modeling software tools such as Maya and 3ds Max. This approach requires both highly specialized and sophisticated skills and massive manual labor. Automatic road generation based on procedural modeling can create road models using specially designed computer algorithms or procedures, reducing the tedious manual editing needed for road modeling dramatically. But most existing procedural modeling methods for road generation put emphasis on the visual effects of the generated roads, not the geometrical and architectural fidelity. This limitation seriously restricts the applicability of the generated road models. To address this problem, this paper proposes a high-fidelity roadway generation method that takes into account road design principles practiced by civil engineering professionals, and as a result, the generated roads can support not only general applications such as games and simulations in which roads are used as 3D assets, but also demanding civil engineering applications, which requires accurate geometrical models of roads. The inputs to the proposed method include road specifications, civil engineering road design rules, terrain information, and surrounding environment. Then the proposed method generates in real time 3D roads that have both high visual and geometrical fidelities. This paper discusses in details the procedures that convert 2D roads specified in shape files into 3D roads and civil engineering road design principles. The proposed method can be used in many applications that have stringent requirements on high precision 3D models, such as driving simulations and road design prototyping. Preliminary results demonstrate the effectiveness of the proposed method.

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

    NASA Technical Reports Server (NTRS)

    Antonsson, Erik; Gombosi, Tamas

    2005-01-01

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

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

    PubMed Central

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

    2013-01-01

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

  1. An ecological model of intimate partner violence perpetration at different levels of severity.

    PubMed

    Smith Slep, Amy M; Foran, Heather M; Heyman, Richard E

    2014-08-01

    Intimate partner violence (IPV) is a significant public health concern. This study proposed and tested an ecological model of both general and clinically significant (i.e., injurious or fear-evoking) IPV perpetration (IPVPerp). Risk and promotive factors from multiple ecological levels of influence (i.e., individual, family, workplace, community) were hypothesized to be important in the prediction of IPVPerp. Although clinically significant IPVPerp and general IPVPerp were hypothesized to relate, specific risks for clinically significant IPVPerp were hypothesized. U.S. Air Force active duty members and civilian spouses (N = 34,861 men; 24,331 women) from 82 sites worldwide completed the 2006 Community Assessment, an anonymous online survey assessing IPVPerp along with a variety of potential risk and promotive factors. Final structural equation models for men and women, cross-validated in holdout samples, clearly supported the relevance of an ecological approach to IPVPerp. Factors from all 4 levels were associated with both general IPVPerp and clinically significant IPVPerp, with relatively distal community and workplace factors operating via more proximal individual and family level variables (e.g., relationship satisfaction). The results suggest a variety of both established and novel potential targets for indirectly targeting general and clinically significant IPVPerp by improving risk profiles at the individual, family, workplace, and community levels. PMID:25000132

  2. Testing a social ecological model for relations between political violence and child adjustment in Northern Ireland.

    PubMed

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

    2010-05-01

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

  3. Model parameters for simulation of physiological lipids.

    PubMed

    Hills, Ronald D; McGlinchey, Nicholas

    2016-05-01

    Coarse grain simulation of proteins in their physiological membrane environment can offer insight across timescales, but requires a comprehensive force field. Parameters are explored for multicomponent bilayers composed of unsaturated lipids DOPC and DOPE, mixed-chain saturation POPC and POPE, and anionic lipids found in bacteria: POPG and cardiolipin. A nonbond representation obtained from multiscale force matching is adapted for these lipids and combined with an improved bonding description of cholesterol. Equilibrating the area per lipid yields robust bilayer simulations and properties for common lipid mixtures with the exception of pure DOPE, which has a known tendency to form nonlamellar phase. The models maintain consistency with an existing lipid-protein interaction model, making the force field of general utility for studying membrane proteins in physiologically representative bilayers. © 2016 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc. PMID:26864972

  4. Simulation of model swimmers near ciliated surfaces

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  5. Refined Transistor Model For Simulation Of SEU

    NASA Technical Reports Server (NTRS)

    Zoutendyk, John A.; Benumof, Reuben

    1988-01-01

    Equivalent base resistance added. Theoretical study develops equations for parameters of Gummel-Poon model of bipolar junction transistor: includes saturation current, amplification factors, charging times, knee currents, capacitances, and resistances. Portion of study concerned with base region goes beyond Gummel-Poon analysis to provide more complete understanding of transistor behavior. Extended theory useful in simulation of single-event upset (SEU) caused in logic circuits by cosmic rays or other ionizing radiation.

  6. Theory, Modeling and Simulation Annual Report 2000

    SciTech Connect

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

    2001-11-01

    This annual report describes the 2000 research accomplishments for the Theory, Modeling, and Simulation (TM and S) directorate, one of the six research organizations in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) at Pacific Northwest National Laboratory (PNNL). EMSL is a U.S. Department of Energy (DOE) national scientific user facility and is the centerpiece of the DOE commitment to providing world-class experimental, theoretical, and computational capabilities for solving the nation's environmental problems.

  7. Theory, Modeling and Simulation Annual Report 2000

    SciTech Connect

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

    2001-11-01

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

  8. Ecological Niche Modeling to Estimate the Distribution of Japanese Encephalitis Virus in Asia

    PubMed Central

    Miller, Robin H.; Masuoka, Penny; Klein, Terry A.; Kim, Heung-Chul; Somer, Todd; Grieco, John

    2012-01-01

    Background Culex tritaeniorhynchus is the primary vector of Japanese encephalitis virus (JEV), a leading cause of encephalitis in Asia. JEV is transmitted in an enzootic cycle involving large wading birds as the reservoirs and swine as amplifying hosts. The development of a JEV vaccine reduced the number of JE cases in regions with comprehensive childhood vaccination programs, such as in Japan and the Republic of Korea. However, the lack of vaccine programs or insufficient coverage of populations in other endemic countries leaves many people susceptible to JEV. The aim of this study was to predict the distribution of Culex tritaeniorhynchus using ecological niche modeling. Methods/Principal Findings An ecological niche model was constructed using the Maxent program to map the areas with suitable environmental conditions for the Cx. tritaeniorhynchus vector. Program input consisted of environmental data (temperature, elevation, rainfall) and known locations of vector presence resulting from an extensive literature search and records from MosquitoMap. The statistically significant Maxent model of the estimated probability of Cx. tritaeniorhynchus presence showed that the mean temperatures of the wettest quarter had the greatest impact on the model. Further, the majority of human Japanese encephalitis (JE) cases were located in regions with higher estimated probability of Cx. tritaeniorhynchus presence. Conclusions/Significance Our ecological niche model of the estimated probability of Cx. tritaeniorhynchus presence provides a framework for better allocation of vector control resources, particularly in locations where JEV vaccinations are unavailable. Furthermore, this model provides estimates of vector probability that could improve vector surveillance programs and JE control efforts. PMID:22724030

  9. Computer Simulation in Chemical Kinetics

    ERIC Educational Resources Information Center

    Anderson, Jay Martin

    1976-01-01

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

  10. A comparison of hydrologic models for ecological flows and water availability

    USGS Publications Warehouse

    Caldwell, Peter V; Kennen, Jonathan G.; Sun, Gee; Kiang, Julie E.; Butcher, John B; Eddy, Michelle C; Hay, Lauren E.; LaFontaine, Jacob H.; Hain, Ernie F.; Nelson, Stacy C; McNulty, Steve G

    2015-01-01

    Robust hydrologic models are needed to help manage water resources for healthy aquatic ecosystems and reliable water supplies for people, but there is a lack of comprehensive model comparison studies that quantify differences in streamflow predictions among model applications developed to answer management questions. We assessed differences in daily streamflow predictions by four fine-scale models and two regional-scale monthly time step models by comparing model fit statistics and bias in ecologically relevant flow statistics (ERFSs) at five sites in the Southeastern USA. Models were calibrated to different extents, including uncalibrated (level A), calibrated to a downstream site (level B), calibrated specifically for the site (level C) and calibrated for the site with adjusted precipitation and temperature inputs (level D). All models generally captured the magnitude and variability of observed streamflows at the five study sites, and increasing level of model calibration generally improved performance. All models had at least 1 of 14 ERFSs falling outside a +/−30% range of hydrologic uncertainty at every site, and ERFSs related to low flows were frequently over-predicted. Our results do not indicate that any specific hydrologic model is superior to the others evaluated at all sites and for all measures of model performance. Instead, we provide evidence that (1) model performance is as likely to be related to calibration strategy as it is to model structure and (2) simple, regional-scale models have comparable performance to the more complex, fine-scale models at a monthly time step.

  11. Simulation and modeling of homogeneous, compressed turbulence

    NASA Technical Reports Server (NTRS)

    Wu, C. T.; Ferziger, J. H.; Chapman, D. R.

    1985-01-01

    Low Reynolds number homogeneous turbulence undergoing low Mach number isotropic and one-dimensional compression was simulated by numerically solving the Navier-Stokes equations. The numerical simulations were performed on a CYBER 205 computer using a 64 x 64 x 64 mesh. A spectral method was used for spatial differencing and the second-order Runge-Kutta method for time advancement. A variety of statistical information was extracted from the computed flow fields. These include three-dimensional energy and dissipation spectra, two-point velocity correlations, one-dimensional energy spectra, turbulent kinetic energy and its dissipation rate, integral length scales, Taylor microscales, and Kolmogorov length scale. Results from the simulated flow fields were used to test one-point closure, two-equation models. A new one-point-closure, three-equation turbulence model which accounts for the effect of compression is proposed. The new model accurately calculates four types of flows (isotropic decay, isotropic compression, one-dimensional compression, and axisymmetric expansion flows) for a wide range of strain rates.

  12. Simulation and modeling of homogeneous, compressed turbulence

    NASA Astrophysics Data System (ADS)

    Wu, C. T.; Ferziger, J. H.; Chapman, D. R.

    1985-05-01

    Low Reynolds number homogeneous turbulence undergoing low Mach number isotropic and one-dimensional compression was simulated by numerically solving the Navier-Stokes equations. The numerical simulations were performed on a CYBER 205 computer using a 64 x 64 x 64 mesh. A spectral method was used for spatial differencing and the second-order Runge-Kutta method for time advancement. A variety of statistical information was extracted from the computed flow fields. These include three-dimensional energy and dissipation spectra, two-point velocity correlations, one-dimensional energy spectra, turbulent kinetic energy and its dissipation rate, integral length scales, Taylor microscales, and Kolmogorov length scale. Results from the simulated flow fields were used to test one-point closure, two-equation models. A new one-point-closure, three-equation turbulence model which accounts for the effect of compression is proposed. The new model accurately calculates four types of flows (isotropic decay, isotropic compression, one-dimensional compression, and axisymmetric expansion flows) for a wide range of strain rates.

  13. Progress in Modeling and Simulation of Batteries

    SciTech Connect

    Turner, John A

    2016-01-01

    Modeling and simulation of batteries, in conjunction with theory and experiment, are important research tools that offer opportunities for advancement of technologies that are critical to electric motors. The development of data from the application of these tools can provide the basis for managerial and technical decision-making. Together, these will continue to transform batteries for electric vehicles. This collection of nine papers presents the modeling and simulation of batteries and the continuing contribution being made to this impressive progress, including topics that cover: * Thermal behavior and characteristics * Battery management system design and analysis * Moderately high-fidelity 3D capabilities * Optimization Techniques and Durability As electric vehicles continue to gain interest from manufacturers and consumers alike, improvements in economy and affordability, as well as adoption of alternative fuel sources to meet government mandates are driving battery research and development. Progress in modeling and simulation will continue to contribute to battery improvements that deliver increased power, energy storage, and durability to further enhance the appeal of electric vehicles.

  14. On the application of multilevel modeling in environmental and ecological studies

    USGS Publications Warehouse

    Qian, S.S.; Cuffney, T.F.; Alameddine, I.; McMahon, G.; Reckhow, K.H.

    2010-01-01

    This paper illustrates the advantages of a multilevel/hierarchical approach for predictive modeling, including flexibility of model formulation, explicitly accounting for hierarchical structure in the data, and the ability to predict the outcome of new cases. As a generalization of the classical approach, the multilevel modeling approach explicitly models the hierarchical structure in the data by considering both the within- and between-group variances leading to a partial pooling of data across all levels in the hierarchy. The modeling framework provides means for incorporating variables at different spatiotemporal scales. The examples used in this paper illustrate the iterative process of model fitting and evaluation, a process that can lead to improved understanding of the system being studied. ?? 2010 by the Ecological Society of America.

  15. Pattern-oriented modelling: a ‘multi-scope’ for predictive systems ecology

    PubMed Central

    Grimm, Volker; Railsback, Steven F.

    2012-01-01

    Modern ecology recognizes that modelling systems across scales and at multiple levels—especially to link population and ecosystem dynamics to individual adaptive behaviour—is essential for making the science predictive. ‘Pattern-oriented modelling’ (POM) is a strategy for doing just this. POM is the multi-criteria design, selection and calibration of models of complex systems. POM starts with identifying a set of patterns observed at multiple scales and levels that characterize a system with respect to the particular problem being modelled; a model from which the patterns emerge should contain the right mechanisms to address the problem. These patterns are then used to (i) determine what scales, entities, variables and processes the model needs, (ii) test and select submodels to represent key low-level processes such as adaptive behaviour, and (iii) find useful parameter values during calibration. Patterns are already often used in these ways, but a mini-review of applications of POM confirms that making the selection and use of patterns more explicit and rigorous can facilitate the development of models with the right level of complexity to understand ecological systems and predict their response to novel conditions. PMID:22144392

  16. Estimating population ecology models for the WWW market: evidence of competitive oligopolies.

    PubMed

    de Cabo, Ruth Mateos; Gimeno, Ricardo

    2013-01-01

    This paper proposes adapting a particle filtering algorithm to model online Spanish real estate and job search market segments based on the Lotka-Volterra competition equations. For this purpose the authors use data on Internet information searches from Google Trends to proxy for market share. Market share evolution estimations are coherent with those observed in Google Trends. The results show evidence of low website incompatibility in the markets analyzed. Competitive oligopolies are most common in such low-competition markets, instead of the monopolies predicted by theoretical ecology models under strong competition conditions. PMID:23244754

  17. Computer Models Simulate Fine Particle Dispersion

    NASA Technical Reports Server (NTRS)

    2010-01-01

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

  18. Qualitative simulation for process modeling and control

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  19. Biomedical Simulation Models of Human Auditory Processes

    NASA Technical Reports Server (NTRS)

    Bicak, Mehmet M. A.

    2012-01-01

    Detailed acoustic engineering models that explore noise propagation mechanisms associated with noise attenuation and transmission paths created when using hearing protectors such as earplugs and headsets in high noise environments. Biomedical finite element (FE) models are developed based on volume Computed Tomography scan data which provides explicit external ear, ear canal, middle ear ossicular bones and cochlea geometry. Results from these studies have enabled a greater understanding of hearing protector to flesh dynamics as well as prioritizing noise propagation mechanisms. Prioritization of noise mechanisms can form an essential framework for exploration of new design principles and methods in both earplug and earcup applications. These models are currently being used in development of a novel hearing protection evaluation system that can provide experimentally correlated psychoacoustic noise attenuation. Moreover, these FE models can be used to simulate the effects of blast related impulse noise on human auditory mechanisms and brain tissue.

  20. Simulating energy, water and carbon fluxes at the shortgrass steppe long term ecological site

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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. GEMRAMS is a coupled atmospheric-biospheric model composed of an atmospheric model, RAMS, and an ecophysiological process-based...

  1. Ecological Niche Modeling for the Prediction of the Geographic Distribution of Cutaneous Leishmaniasis in Tunisia.

    PubMed

    Chalghaf, Bilel; Chlif, Sadok; Mayala, Benjamin; Ghawar, Wissem; Bettaieb, Jihène; Harrabi, Myriam; Benie, Goze Bertin; Michael, Edwin; Salah, Afif Ben

    2016-04-01

    Cutaneous leishmaniasis is a very complex disease involving multiple factors that limit its emergence and spatial distribution. Prediction of cutaneous leishmaniasis epidemics in Tunisia remains difficult because most of the epidemiological tools used so far are descriptive in nature and mainly focus on a time dimension. The purpose of this work is to predict the potential geographic distribution of Phlebotomus papatasi and zoonotic cutaneous leishmaniasis caused by Leishmania major in Tunisia using Grinnellian ecological niche modeling. We attempted to assess the importance of environmental factors influencing the potential distribution of P. papatasi and cutaneous leishmaniasis caused by L. major. Vectors were trapped in central Tunisia during the transmission season using CDC light traps (John W. Hock Co., Gainesville, FL). A global positioning system was used to record the geographical coordinates of vector occurrence points and households tested positive for cutaneous leishmaniasis caused by L. major. Nine environmental layers were used as predictor variables to model the P. papatasi geographical distribution and five variables were used to model the L. major potential distribution. Ecological niche modeling was used to relate known species' occurrence points to values of environmental factors for these same points to predict the presence of the species in unsampled regions based on the value of the predictor variables. Rainfall and temperature contributed the most as predictors for sand flies and human case distributions. Ecological niche modeling anticipated the current distribution of P. papatasi with the highest suitability for species occurrence in the central and southeastern part of Tunisian. Furthermore, our study demonstrated that governorates of Gafsa, Sidi Bouzid, and Kairouan are at highest epidemic risk. PMID:26856914

  2. . Ecological conceptual models: a framework and case study on ecosystem management for South Florida sustainability

    USGS Publications Warehouse

    Gentile, J.H.; Harwell, M.A.; Cropper, W., Jr.; Harwell, C. C.; DeAngelis, Donald L.; Davis, S.; Ogden, J.C.; Lirman, D.

    2001-01-01

    The Everglades and South Florida ecosystems are the focus of national and international attention because of their current degraded and threatened state. Ecological risk assessment, sustainability and ecosystem and adaptive management principles and processes are being used nationally as a decision and policy framework for a variety of types of ecological assessments. The intent of this study is to demonstrate the application of these paradigms and principles at a regional scale. The effects-directed assessment approach used in this study consists of a retrospective, eco-epidemiological phase to determine the causes for the current conditions and a prospective predictive risk-based assessment using scenario analysis to evaluate future options. Embedded in these assessment phases is a process that begins with the identification of goals and societal preferences which are used to develop an integrated suite of risk-based and policy relevant conceptual models. Conceptual models are used to illustrate the linkages among management (societal) actions, environmental stressors, and societal/ecological effects, and provide the basis for developing and testing causal hypotheses. These models, developed for a variety of landscape units and their drivers, stressors, and endpoints, are used to formulate hypotheses to explain the current conditions. They are also used as the basis for structuring management scenarios and analyses to project the temporal and spatial magnitude of risk reduction and system recovery. Within the context of recovery, the conceptual models are used in the initial development of performance criteria for those stressors that are determined to be most important in shaping the landscape, and to guide the use of numerical models used to develop quantitative performance criteria in the scenario analysis. The results will be discussed within an ecosystem and adaptive management framework that provides the foundation for decision making.

  3. Ecological Niche Modeling for the Prediction of the Geographic Distribution of Cutaneous Leishmaniasis in Tunisia

    PubMed Central

    Chalghaf, Bilel; Chlif, Sadok; Mayala, Benjamin; Ghawar, Wissem; Bettaieb, Jihène; Harrabi, Myriam; Benie, Goze Bertin; Michael, Edwin; Salah, Afif Ben

    2016-01-01

    Cutaneous leishmaniasis is a very complex disease involving multiple factors that limit its emergence and spatial distribution. Prediction of cutaneous leishmaniasis epidemics in Tunisia remains difficult because most of the epidemiological tools used so far are descriptive in nature and mainly focus on a time dimension. The purpose of this work is to predict the potential geographic distribution of Phlebotomus papatasi and zoonotic cutaneous leishmaniasis caused by Leishmania major in Tunisia using Grinnellian ecological niche modeling. We attempted to assess the importance of environmental factors influencing the potential distribution of P. papatasi and cutaneous leishmaniasis caused by L. major. Vectors were trapped in central Tunisia during the transmission season using CDC light traps (John W. Hock Co., Gainesville, FL). A global positioning system was used to record the geographical coordinates of vector occurrence points and households tested positive for cutaneous leishmaniasis caused by L. major. Nine environmental layers were used as predictor variables to model the P. papatasi geographical distribution and five variables were used to model the L. major potential distribution. Ecological niche modeling was used to relate known species' occurrence points to values of environmental factors for these same points to predict the presence of the species in unsampled regions based on the value of the predictor variables. Rainfall and temperature contributed the most as predictors for sand flies and human case distributions. Ecological niche modeling anticipated the current distribution of P. papatasi with the highest suitability for species occurrence in the central and southeastern part of Tunisian. Furthermore, our study demonstrated that governorates of Gafsa, Sidi Bouzid, and Kairouan are at highest epidemic risk. PMID:26856914

  4. Atomistic modeling and simulation of nanopolycrystalline solids

    NASA Astrophysics Data System (ADS)

    Yang, Zidong

    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

  5. Integrating Visualizations into Modeling NEST Simulations

    PubMed Central

    Nowke, Christian; Zielasko, Daniel; Weyers, Benjamin; Peyser, Alexander; Hentschel, Bernd; Kuhlen, Torsten W.

    2015-01-01

    Modeling large-scale spiking neural networks showing realistic biological behavior in their dynamics is a complex and tedious task. Since these networks consist of millions of interconnected neurons, their simulation produces an immense amount of data. In recent years it has become possible to simulate even larger networks. However, solutions to assist researchers in understanding the simulation's complex emergent behavior by means of visualization are still lacking. While developing tools to partially fill this gap, we encountered the challenge to integrate these tools easily into the neuroscientists' daily workflow. To understand what makes this so challenging, we looked into the workflows of our collaborators and analyzed how they use the visualizations to solve their daily problems. We identified two major issues: first, the analysis process can rapidly change focus which requires to switch the visualization tool that assists in the current problem domain. Second, because of the heterogeneous data that results from simulations, researchers want to relate data to investigate these effectively. Since a monolithic application model, processing and visualizing all data modalities and reflecting all combinations of possible workflows in a holistic way, is most likely impossible to develop and to maintain, a software architecture that offers specialized visualization tools that run simultaneously and can be linked together to reflect the current workflow, is a more feasible approach. To this end, we have developed a software architecture that allows neuroscientists to integrate visualization tools more closely into the modeling tasks. In addition, it forms the basis for semantic linking of different visualizations to reflect the current workflow. In this paper, we present this architecture and substantiate the usefulness of our approach by common use cases we encountered in our collaborative work. PMID:26733860

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

    PubMed Central

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

    2009-01-01

    Background Autoregressive regression coefficients for Anopheles arabiensis aquatic habitat models are usually assessed using global error techniques and are reported as error covariance matrices. A global statistic, however, will summarize error estimates from multiple habitat locations. This makes it difficult to identify where there are clusters of An. arabiensis aquatic habitats of acceptable prediction. It is therefore useful to conduct some form of spatial error analysis to detect clusters of An. arabiensis aquatic habitats based on uncertainty residuals from individual sampled habitats. In this research, a method of error estimation for spatial simulation models was demonstrated using autocorrelation indices and eigenfunction spatial filters to distinguish among the effects of parameter uncertainty on a stochastic simulation of ecological sampled Anopheles aquatic habitat covariates. A test for diagnostic checking error residuals in an An. arabiensis aquatic habitat model may enable intervention efforts targeting productive habitats clusters, based on larval/pupal productivity, by using the asymptotic distribution of parameter estimates from a residual autocovariance matrix. The models considered in this research extends a normal regression analysis previously considered in the literature. Methods Field and remote-sampled data were collected during July 2006 to December 2007 in Karima rice-village complex in Mwea, Kenya. SAS 9.1.4® was used to explore univariate statistics, correlations, distributions, and to generate global autocorrelation statistics from the ecological sampled datasets. A local autocorrelation index was also generated using spatial covariance parameters (i.e., Moran's Indices) in a SAS/GIS® database. The Moran's statistic was decomposed into orthogonal and uncorrelated synthetic map pattern components using a Poisson model with a gamma-distributed mean (i.e. negative binomial regression). The eigenfunction values from the spatial

  7. LISP based simulation generators for modeling complex space processes

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  8. Use of model discrimination techniques to improve hydrologic models under ecological constraints: the case of the Maggia Valley, Southern Switzerland

    NASA Astrophysics Data System (ADS)

    Foglia, L.; Mehl, S. W.; Hill, M. C.; Burlando, P.

    2009-04-01

    Model discrimination techniques are used to evaluate alternative conceptual models. Thorough consideration of alternative conceptual models is an important and often neglected step in the study of many natural systems, including groundwater systems. This means that many modelling efforts are less useful for system management than they could be because they exclude alternatives considered important by some stakeholders, which makes them vulnerable to criticism. Important steps include identifying reasonable alternative models and possibly using model averaging to improve predictions and measures of prediction uncertainty. Here we used the computer code MMA (Multi-Model Analysis) as a modelling tool to help: (1) model development, (2) make predictions, and (3) understand the physical processes most important to the system. We focus on the ability of a groundwater model constructed using MODFLOW to predict heads and flows in the Maggia Valley, Southern Switzerland, where connections between groundwater, surface water and ecology are of interest. Sixty-four alternative models were designed deterministically and differ in how the river, recharge, bedrock topography, and hydraulic conductivity are characterized. None of the models correctly represent heads and flows in the Northern and Southern part of the valley simultaneously. A cross-validation experiment was conducted to compare model discrimination results with the ability of the models to predict eight heads and three flows to the stream along three reaches midway along the valley where ecological consequences and, therefore, model accuracy are of great concern. Results suggest: (1) Model averaging appears to have improved prediction accuracy in the problem considered. (2) The most significant model improvements occurred with introduction of spatially distributed recharge and improved bedrock topography. (3) The simplest models poorly represented the system in the area of interest.

  9. [Modeling and Simulation of Spectral Polarimetric BRDF].

    PubMed

    Ling, Jin-jiang; Li, Gang; Zhang, Ren-bin; Tang, Qian; Ye, Qiu

    2016-01-01

    Under the conditions of the polarized light, The reflective surface of the object is affected by many factors, refractive index, surface roughness, and so the angle of incidence. For the rough surface in the different wavelengths of light exhibit different reflection characteristics of polarization, a spectral polarimetric BRDF based on Kirchhof theory is proposee. The spectral model of complex refraction index is combined with refraction index and extinction coefficient spectral model which were got by using the known complex refraction index at different value. Then get the spectral model of surface roughness derived from the classical surface roughness measuring method combined with the Fresnel reflection function. Take the spectral model of refraction index and roughness into the BRDF model, then the spectral polarimetirc BRDF model is proposed. Compare the simulation results of the refractive index varies with wavelength, roughness is constant, the refraction index and roughness both vary with wavelength and origin model with other papers, it shows that, the spectral polarimetric BRDF model can show the polarization characteristics of the surface accurately, and can provide a reliable basis for the application of polarization remote sensing, and other aspects of the classification of substances. PMID:27228737

  10. Integration of modeling components into ecological and human health risk assessments

    SciTech Connect

    Chernoff, H.; Tomchuk, D.

    1995-12-31

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

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

    SciTech Connect

    Diamond, J.; Miller, J.

    1995-12-31

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

    For the embodiment of natural resources and environmental emissions in Chinese economy 2005, a biophysical balance modeling is carried out based on an extension of the economic input-output table into an ecological one integrating the economy with its various environmental driving forces. Included resource flows into the primary resource sectors and environmental emission flows from the primary emission sectors belong to seven categories as energy resources in terms of fossil fuels, hydropower and nuclear energy, biomass, and other sources; freshwater resources; greenhouse gas emissions in terms of CO2, CH4, and N2O; industrial wastes in terms of waste water, waste gas, and waste solid; exergy in terms of fossil fuel resources, biological resources, mineral resources, and environmental resources; solar emergy and cosmic emergy in terms of climate resources, soil, fossil fuels, and minerals. The resulted database for embodiment intensity and sectoral embodiment of natural resources and environmental emissions is of essential implications in context of systems ecology and ecological economics in general and of global climate change in particular.

  13. Best Practices for Crash Modeling and Simulation

    NASA Technical Reports Server (NTRS)

    Fasanella, Edwin L.; Jackson, Karen E.

    2002-01-01

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

  14. Simulation Assisted Risk Assessment: Blast Overpressure Modeling

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    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.

  15. A Simple Memristor Model for Circuit Simulations

    NASA Astrophysics Data System (ADS)

    Fullerton, Farrah-Amoy; Joe, Aaleyah; Gergel-Hackett, Nadine; Department of Chemistry; Physics Team

    This work describes the development of a model for the memristor, a novel nanoelectronic technology. The model was designed to replicate the real-world electrical characteristics of previously fabricated memristor devices, but was constructed with basic circuit elements using a free widely available circuit simulator, LT Spice. The modeled memrsistors were then used to construct a circuit that performs material implication. Material implication is a digital logic that can be used to perform all of the same basic functions as traditional CMOS gates, but with fewer nanoelectronic devices. This memristor-based digital logic could enable memristors' use in new paradigms of computer architecture with advantages in size, speed, and power over traditional computing circuits. Additionally, the ability to model the real-world electrical characteristics of memristors in a free circuit simulator using its standard library of elements could enable not only the development of memristor material implication, but also the development of a virtually unlimited array of other memristor-based circuits.

  16. Desktop Modeling and Simulation: Parsimonious, yet Effective Discrete-Event Simulation Analysis

    NASA Technical Reports Server (NTRS)

    Bradley, James R.

    2012-01-01

    This paper evaluates how quickly students can be trained to construct useful discrete-event simulation models using Excel The typical supply chain used by many large national retailers is described, and an Excel-based simulation model is constructed of it The set of programming and simulation skills required for development of that model are then determined we conclude that six hours of training are required to teach the skills to MBA students . The simulation presented here contains all fundamental functionallty of a simulation model, and so our result holds for any discrete-event simulation model. We argue therefore that Industry workers with the same technical skill set as students having completed one year in an MBA program can be quickly trained to construct simulation models. This result gives credence to the efficacy of Desktop Modeling and Simulation whereby simulation analyses can be quickly developed, run, and analyzed with widely available software, namely Excel.

  17. Tropical Forests, Savannas and Grasslands: Bridging the Knowledge Gap Between Ecology and Dynamic Global Vegetation Models

    NASA Astrophysics Data System (ADS)

    Baudena, M.; Dekker, S. C.; van Bodegom, P. M.; Cuesta, B.; Higgins, S. I.; Lehsten, V.; Reick, C. H.; Rietkerk, M.; Scheiter, S.; Yin, Z.; Zavala, M. A.; Brovkin, V.

    2014-12-01

    Due to global climate change, tropical forest, savanna, and grassland biomes, and the transitions between them, are expected to undergo major changes in the future. Dynamic Global Vegetation Models (DGVMs) are largely used to understand vegetation dynamics under present climate, and to predict its changes under future conditions. However, several DGVMs display high uncertainty in predicting vegetation in tropical areas. Here we present the results of a comparative analysis of three different DGVMs (JSBACH, LPJ-GUESS-SPITFIRE and aDGVM) with regard to their different representations of the ecological mechanisms and feedbacks that determine the forest, savanna and grassland biomes, in an attempt to bridge the knowledge gap between ecology and global modelling. We compared model outcomes to observed tree cover along a mean annual precipitation gradient in Africa. Through these comparisons, and by drawing on the large number of recent studies that have delivered new insights into the ecology of tropical ecosystems in general, and of savannas in particular, we identify two main mechanisms that need an improved representation in the DGVMs. The first mechanism encompasses water limitation to tree growth, and tree-grass competition for water, which are key factors in determining savanna occurrence in arid and semi-arid areas. The second is a grass-fire feedback, which maintains both forest and savannas in mesic areas. Grasses constitute the majority of the fuel load, and at the same time benefit from the openness of the landscape after fires, since they recover faster than trees. Additionally, these two mechanisms are better represented when the models also include tree life stages (adults and seedlings), and distinguish between fire-prone and shade-tolerant savanna trees, and fire-resistant and shade-intolerant forest trees. Including these basic elements could improve the predictive ability of the DGVMs, not only under current climate conditions but also and especially

  18. Forests, savannas, and grasslands: bridging the knowledge gap between ecology and Dynamic Global Vegetation Models

    NASA Astrophysics Data System (ADS)

    Baudena, M.; Dekker, S. C.; van Bodegom, P. M.; Cuesta, B.; Higgins, S. I.; Lehsten, V.; Reick, C. H.; Rietkerk, M.; Scheiter, S.; Yin, Z.; Zavala, M. A.; Brovkin, V.

    2015-03-01

    The forest, savanna, and grassland biomes, and the transitions between them, are expected to undergo major changes in the future due to global climate change. Dynamic global vegetation models (DGVMs) are very useful for understanding vegetation dynamics under the present climate, and for predicting its changes under future conditions. However, several DGVMs display high uncertainty in predicting vegetation in tropical areas. Here we perform a comparative analysis of three different DGVMs (JSBACH, LPJ-GUESS-SPITFIRE and aDGVM) with regard to their representation of the ecological mechanisms and feedbacks that determine the forest, savanna, and grassland biomes, in an attempt to bridge the knowledge gap between ecology and global modeling. The outcomes of the models, which include different mechanisms, are compared to observed tree cover along a mean annual precipitation gradient in Africa. By drawing on the large number of recent studies that have delivered new insights into the ecology of tropical ecosystems in general, and of savannas in particular, we identify two main mechanisms that need improved representation in the examined DGVMs. The first mechanism includes water limitation to tree growth, and tree-grass competition for water, which are key factors in determining savanna presence in arid and semi-arid areas. The second is a grass-fire feedback, which maintains both forest and savanna presence in mesic areas. Grasses constitute the majority of the fuel load, and at the same time benefit from the openness of the landscape after fires, since they recover faster than trees. Additionally, these two mechanisms are better represented when the models also include tree life stages (adults and seedlings), and distinguish between fire-prone and shade-tolerant forest trees, and fire-resistant and shade-intolerant savanna trees. Including these basic elements could improve the predictive ability of the DGVMs, not only under current climate conditions but also and

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

    PubMed Central

    2012-01-01

    Background If the geographical displacement of one species by another is accompanied by hybridization, mitochondrial DNA can introgress asymmetrically, from the outcompeted species into the invading species, over a large area. We explore this phenomenon using the two parapatric crested newt species, Triturus macedonicus and T. karelinii, distributed on the Balkan Peninsula in south-eastern Europe, as a model. Results We first delimit a ca. 54,000 km2 area in which T. macedonicus contains T. karelinii mitochondrial DNA. This introgression zone bisects the range of T. karelinii, cutting off a T. karelinii enclave. The high similarity of introgressed mitochondrial DNA haplotypes with those found in T. karelinii suggests a recent transfer across the species boundary. We then use ecological niche modeling to explore habitat suitability of the location of the present day introgression zone under current, mid-Holocene and Last Glacial Maximum conditions. This area was inhospitable during the Last Glacial Maximum for both species, but would have been habitable at the mid-Holocene. Since the mid-Holocene, habitat suitability generally increased for T. macedonicus, whereas it decreased for T. karelinii. Conclusion The presence of a T. karelinii enclave suggests that T. karelinii was the first to colonize the area where the present day introgression zone is positioned after the Last Glacial Maximum. Subsequently, we propose T. karelinii was outcompeted by T. macedonicus, which captured T. karelinii mitochondrial DNA via introgressive hybridization in the process. Ecological niche modeling suggests that this replacement was likely facilitated by a shift in climate since the mid-Holocene. We suggest that the northwestern part of the current introgression zone was probably never inhabited by T. karelinii itself, and that T. karelinii mitochondrial DNA spread there through T. macedonicus exclusively. Considering the spatial distribution of the introgressed mitochondrial DNA and

  20. Forests, savannas and grasslands: bridging the knowledge gap between ecology and Dynamic Global Vegetation Models

    NASA Astrophysics Data System (ADS)

    Baudena, M.; Dekker, S. C.; van Bodegom, P. M.; Cuesta, B.; Higgins, S. I.; Lehsten, V.; Reick, C. H.; Rietkerk, M.; Scheiter, S.; Yin, Z.; Zavala, M. A.; Brovkin, V.

    2014-06-01

    The forest, savanna, and grassland biomes, and the transitions between them, are expected to undergo major changes in the future, due to global climate change. Dynamic Global Vegetation Models (DGVMs) are very useful to understand vegetation dynamics under present climate, and to predict its changes under future conditions. However, several DGVMs display high uncertainty in predicting vegetation in tropical areas. Here we perform a comparative analysis of three different DGVMs (JSBACH, LPJ-GUESS-SPITFIRE and aDGVM) with regard to their representation of the ecological mechanisms and feedbacks that determine the forest, savanna and grassland biomes, in an attempt to bridge the knowledge gap between ecology and global modelling. Model outcomes, obtained including different mechanisms, are compared to observed tree cover along a mean annual precipitation gradient in Africa. Through these comparisons, and by drawing on the large number of recent studies that have delivered new insights into the ecology of tropical ecosystems in general, and of savannas in particular, we identify two main mechanisms that need an improved representation in the DGVMs. The first mechanism includes water limitation to tree growth, and tree-grass competition for water, which are key factors in determining savanna presence in arid and semi-arid areas. The second is a grass-fire feedback, which maintains both forest and savanna occurrences in mesic areas. Grasses constitute the majority of the fuel load, and at the same time benefit from the openness of the landscape after fires, since they recover faster than trees. Additionally, these two mechanisms are better represented when the models also include tree life stages (adults and seedlings), and distinguish between fire-prone and shade-tolerant savanna trees, and fire-resistant and shade-intolerant forest trees. Including these basic elements could improve the predictive ability of the DGVMs, not only under current climate conditions but also