WorldWideScience

Sample records for scenario tree modelling

  1. Scenario tree airline fleet planning for demand uncertainty

    NARCIS (Netherlands)

    Repko, M.G.J.; Lopes dos Santos, Bruno F.

    2017-01-01

    This paper proposes an innovative multi-period modeling approach to solve the airline fleet planning problem under demand uncertainty. The problem is modeled using a scenario tree approach. The tree is composed of nodes, which represent points of decision in multiple time stages of the planning

  2. OBEST: The Object-Based Event Scenario Tree Methodology

    International Nuclear Information System (INIS)

    WYSS, GREGORY D.; DURAN, FELICIA A.

    2001-01-01

    Event tree analysis and Monte Carlo-based discrete event simulation have been used in risk assessment studies for many years. This report details how features of these two methods can be combined with concepts from object-oriented analysis to develop a new risk assessment methodology with some of the best features of each. The resultant Object-Based Event Scenarios Tree (OBEST) methodology enables an analyst to rapidly construct realistic models for scenarios for which an a priori discovery of event ordering is either cumbersome or impossible (especially those that exhibit inconsistent or variable event ordering, which are difficult to represent in an event tree analysis). Each scenario produced by OBEST is automatically associated with a likelihood estimate because probabilistic branching is integral to the object model definition. The OBEST method uses a recursive algorithm to solve the object model and identify all possible scenarios and their associated probabilities. Since scenario likelihoods are developed directly by the solution algorithm, they need not be computed by statistical inference based on Monte Carlo observations (as required by some discrete event simulation methods). Thus, OBEST is not only much more computationally efficient than these simulation methods, but it also discovers scenarios that have extremely low probabilities as a natural analytical result--scenarios that would likely be missed by a Monte Carlo-based method. This report documents the OBEST methodology, the demonstration software that implements it, and provides example OBEST models for several different application domains, including interactions among failing interdependent infrastructure systems, circuit analysis for fire risk evaluation in nuclear power plants, and aviation safety studies

  3. Credibilistic multi-period portfolio optimization based on scenario tree

    Science.gov (United States)

    Mohebbi, Negin; Najafi, Amir Abbas

    2018-02-01

    In this paper, we consider a multi-period fuzzy portfolio optimization model with considering transaction costs and the possibility of risk-free investment. We formulate a bi-objective mean-VaR portfolio selection model based on the integration of fuzzy credibility theory and scenario tree in order to dealing with the markets uncertainty. The scenario tree is also a proper method for modeling multi-period portfolio problems since the length and continuity of their horizon. We take the return and risk as well cardinality, threshold, class, and liquidity constraints into consideration for further compliance of the model with reality. Then, an interactive dynamic programming method, which is based on a two-phase fuzzy interactive approach, is employed to solve the proposed model. In order to verify the proposed model, we present an empirical application in NYSE under different circumstances. The results show that the consideration of data uncertainty and other real-world assumptions lead to more practical and efficient solutions.

  4. Scenario evolution: Interaction between event tree construction and numerical analyses

    International Nuclear Information System (INIS)

    Barr, G.E.; Barnard, R.W.; Dockery, H.A.; Dunn, E.; MacIntyre, A.T.

    1991-01-01

    Construction of well-posed scenarios for the range of conditions possible at any proposed repository site is a critical first step to assessing total system performance. Even tree construction is the method that is being used to develop potential failure scenarios for the proposed nuclear waste repository at Yucca Mountain. An event tree begins with an initial event or condition. Subsequent events are listed in a sequence, leading eventually to release of radionuclides to the accessible environment. Ensuring the validity of the scenarios requires iteration between problems constructed using scenarios contained in the event tree sequence, experimental results, and numerical analyses. Details not adequately captured within the tree initially may become more apparent as a result of analyses. To illustrate this process, we discuss the iterations used to develop numerical analyses for PACE-90 using basaltic igneous activity and human-intrusion event trees

  5. Scenario evolution: Interaction between event tree construction and numerical analyses

    International Nuclear Information System (INIS)

    Barr, G.E.; Barnard, R.W.; Dockery, H.A.; Dunn, E.; MacIntyre, A.T.

    1990-01-01

    Construction of well-posed scenarios for the range of conditions possible at any proposed repository site is a critical first step to assessing total system performance. Event tree construction is the method that is being used to develop potential failure scenarios for the proposed nuclear waste repository at Yucca Mountain. An event tree begins with an initial event or condition. Subsequent events are listed in a sequence, leading eventually to release of radionuclides to the accessible environment. Ensuring the validity of the scenarios requires iteration between problems constructed using scenarios contained in the event tree sequence, experimental results, and numerical analyses. Details not adequately captured within the tree initially may become more apparent as a result of analyses. To illustrate this process, the authors discuss the iterations used to develop numerical analyses for PACE-90 (Performance Assessment Calculational Exercises) using basaltic igneous activity and human-intrusion event trees

  6. Scenario Modeling of Thermal Influence from Forest Fire Front on a Coniferous Tree Trunk

    Directory of Open Access Journals (Sweden)

    Baranovskiy Nikolay V.

    2016-01-01

    Full Text Available Scenario research results of heat transfer and tissue damage in three-layered tree trunk influenced by heat flux from forest fire are presented. The problem is solved in two-dimensional statement in polar coordinates. The typical range of influence parameters (heat flux from forest fire front, trunk radius, coniferous species, air temperature, duration of exposure and distance from fire line is considered. Temperature distributions in different moments of time are obtained. Condition of tree damage by forest fire influence is under consideration in this research. Information summarized using tables with scenario and fire consequences results.

  7. Complex accident scenarios modelled and analysed by Stochastic Petri Nets

    International Nuclear Information System (INIS)

    Nývlt, Ondřej; Haugen, Stein; Ferkl, Lukáš

    2015-01-01

    This paper is focused on the usage of Petri nets for an effective modelling and simulation of complicated accident scenarios, where an order of events can vary and some events may occur anywhere in an event chain. These cases are hardly manageable by traditional methods as event trees – e.g. one pivotal event must be often inserted several times into one branch of the tree. Our approach is based on Stochastic Petri Nets with Predicates and Assertions and on an idea, which comes from the area of Programmable Logic Controllers: an accidental scenario is described as a net of interconnected blocks, which represent parts of the scenario. So the scenario is firstly divided into parts, which are then modelled by Petri nets. Every block can be easily interconnected with other blocks by input/output variables to create complex ones. In the presented approach, every event or a part of a scenario is modelled only once, independently on a number of its occurrences in the scenario. The final model is much more transparent then the corresponding event tree. The method is shown in two case studies, where the advanced one contains a dynamic behavior. - Highlights: • Event & Fault trees have problems with scenarios where an order of events can vary. • Paper presents a method for modelling and analysis of dynamic accident scenarios. • The presented method is based on Petri nets. • The proposed method solves mentioned problems of traditional approaches. • The method is shown in two case studies: simple and advanced (with dynamic behavior)

  8. Tree cover in Central Africa: determinants and sensitivity under contrasted scenarios of global change.

    Science.gov (United States)

    Aleman, Julie C; Blarquez, Olivier; Gourlet-Fleury, Sylvie; Bremond, Laurent; Favier, Charly

    2017-01-30

    Tree cover is a key variable for ecosystem functioning, and is widely used to study tropical ecosystems. But its determinants and their relative importance are still a matter of debate, especially because most regional and global analyses have not considered the influence of agricultural practices. More information is urgently needed regarding how human practices influence vegetation structure. Here we focused in Central Africa, a region still subjected to traditional agricultural practices with a clear vegetation gradient. Using remote sensing data and global databases, we calibrated a Random Forest model to correlatively link tree cover with climatic, edaphic, fire and agricultural practices data. We showed that annual rainfall and accumulated water deficit were the main drivers of the distribution of tree cover and vegetation classes (defined by the modes of tree cover density), but agricultural practices, especially pastoralism, were also important in determining tree cover. We simulated future tree cover with our model using different scenarios of climate and land-use (agriculture and population) changes. Our simulations suggest that tree cover may respond differently regarding the type of scenarios, but land-use change was an important driver of vegetation change even able to counterbalance the effect of climate change in Central Africa.

  9. Scenario tree generation and multi-asset financial optimization problems

    DEFF Research Database (Denmark)

    Geyer, Alois; Hanke, Michael; Weissensteiner, Alex

    2013-01-01

    We compare two popular scenario tree generation methods in the context of financial optimization: moment matching and scenario reduction. Using a simple problem with a known analytic solution, moment matching-when ensuring absence of arbitrage-replicates this solution precisely. On the other hand...

  10. A scenario tree model for the Canadian Notifiable Avian Influenza Surveillance System and its application to estimation of probability of freedom and sample size determination.

    Science.gov (United States)

    Christensen, Jette; Stryhn, Henrik; Vallières, André; El Allaki, Farouk

    2011-05-01

    In 2008, Canada designed and implemented the Canadian Notifiable Avian Influenza Surveillance System (CanNAISS) with six surveillance activities in a phased-in approach. CanNAISS was a surveillance system because it had more than one surveillance activity or component in 2008: passive surveillance; pre-slaughter surveillance; and voluntary enhanced notifiable avian influenza surveillance. Our objectives were to give a short overview of two active surveillance components in CanNAISS; describe the CanNAISS scenario tree model and its application to estimation of probability of populations being free of NAI virus infection and sample size determination. Our data from the pre-slaughter surveillance component included diagnostic test results from 6296 serum samples representing 601 commercial chicken and turkey farms collected from 25 August 2008 to 29 January 2009. In addition, we included data from a sub-population of farms with high biosecurity standards: 36,164 samples from 55 farms sampled repeatedly over the 24 months study period from January 2007 to December 2008. All submissions were negative for Notifiable Avian Influenza (NAI) virus infection. We developed the CanNAISS scenario tree model, so that it will estimate the surveillance component sensitivity and the probability of a population being free of NAI at the 0.01 farm-level and 0.3 within-farm-level prevalences. We propose that a general model, such as the CanNAISS scenario tree model, may have a broader application than more detailed models that require disease specific input parameters, such as relative risk estimates. Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.

  11. Stochastic Unit Commitment Based on Multi-Scenario Tree Method Considering Uncertainty

    Directory of Open Access Journals (Sweden)

    Kyu-Hyung Jo

    2018-03-01

    Full Text Available With the increasing penetration of renewable energy, it is difficult to schedule unit commitment (UC in a power system because of the uncertainty associated with various factors. In this paper, a new solution procedure based on a multi-scenario tree method (MSTM is presented and applied to the proposed stochastic UC problem. In this process, the initial input data of load and wind power are modeled as different levels using the mean absolute percentage error (MAPE. The load and wind scenarios are generated using Monte Carlo simulation (MCS that considers forecasting errors. These multiple scenarios are applied in the MSTM for solving the stochastic UC problem, including not only the load and wind power uncertainties, but also sudden outages of the thermal unit. When the UC problem has been formulated, the simulation is conducted for 24-h period by using the short-term UC model, and the operating costs and additional reserve requirements are thus obtained. The effectiveness of the proposed solution approach is demonstrated through a case study based on a modified IEEE-118 bus test system.

  12. AUTOMATIC TREE-CROWN DETECTION IN CHALLENGING SCENARIOS

    Directory of Open Access Journals (Sweden)

    D. Bulatov

    2016-06-01

    Full Text Available In this paper, a new procedure for individual tree detection and modeling is presented. The input of this procedure consists of a normalized digital surface model NDSM, and a possibly error-prone classification result. The procedure is modular so that the functionality, the advantages and the disadvantages for every single module will be explained. The most important technical contributions of the paper are: Employing watershed transformation combined with classification results, applying hotspots detectors for identifying treetops in groups of trees, and correcting NDSM by detecting and geometric reconstruction of small anomalies, such as earth walls. Two minor contributions are made up by a detailed literature research on available methods for individual tree detection and estimation of tree-crowns for clearly identified trees in order to reduce arbitrariness by assigning trees to one of the few types in the output model.

  13. Attack Trees for Practical Security Assessment: Ranking of Attack Scenarios with ADTool 2.0

    NARCIS (Netherlands)

    Gadyatskaya, Olga; Jhawar, Ravi; Kordy, P.T.; Lounis, Karim; Mauw, Sjouke; Trujillo-Rasua, Rolando

    2016-01-01

    In this tool demonstration paper we present the ADTool2.0: an open-source software tool for design, manipulation and analysis of attack trees. The tool supports ranking of attack scenarios based on quantitative attributes entered by the user; it is scriptable; and it incorporates attack trees with

  14. A Method to Quantify Plant Availability and Initiating Event Frequency Using a Large Event Tree, Small Fault Tree Model

    International Nuclear Information System (INIS)

    Kee, Ernest J.; Sun, Alice; Rodgers, Shawn; Popova, ElmiraV; Nelson, Paul; Moiseytseva, Vera; Wang, Eric

    2006-01-01

    South Texas Project uses a large fault tree to produce scenarios (minimal cut sets) used in quantification of plant availability and event frequency predictions. On the other hand, the South Texas Project probabilistic risk assessment model uses a large event tree, small fault tree for quantifying core damage and radioactive release frequency predictions. The South Texas Project is converting its availability and event frequency model to use a large event tree, small fault in an effort to streamline application support and to provide additional detail in results. The availability and event frequency model as well as the applications it supports (maintenance and operational risk management, system engineering health assessment, preventive maintenance optimization, and RIAM) are briefly described. A methodology to perform availability modeling in a large event tree, small fault tree framework is described in detail. How the methodology can be used to support South Texas Project maintenance and operations risk management is described in detail. Differences with other fault tree methods and other recently proposed methods are discussed in detail. While the methods described are novel to the South Texas Project Risk Management program and to large event tree, small fault tree models, concepts in the area of application support and availability modeling have wider applicability to the industry. (authors)

  15. A time-dependent event tree technique for modelling recovery operations

    International Nuclear Information System (INIS)

    Kohut, P.; Fitzpatrick, R.

    1991-01-01

    The development of a simplified time dependent event tree methodology is presented. The technique is especially applicable to describe recovery operations in nuclear reactor accident scenarios initiated by support system failures. The event tree logic is constructed using time dependent top events combined with a damage function that contains information about the final state time behavior of the reactor core. Both the failure and the success states may be utilized for the analysis. The method is illustrated by modeling the loss of service water function with special emphasis on the RCP [reactor coolant pump] seal LOCA [loss of coolant accident] scenario. 5 refs., 2 figs., 2 tabs

  16. Online scenario labeling using a hidden Markov model for assessment of nuclear plant state

    International Nuclear Information System (INIS)

    Zamalieva, Daniya; Yilmaz, Alper; Aldemir, Tunc

    2013-01-01

    By taking into account both aleatory and epistemic uncertainties within the same probabilistic framework, dynamic event trees (DETs) provide more comprehensive and systematic coverage of possible scenarios following an initiating event compared to conventional event trees. When DET generation algorithms are applied to complex realistic systems, extremely large amounts of data can be produced due to both the large number of scenarios generated following a single initiating event and the large number of data channels that represent these scenarios. In addition, the computational time required for the simulation of each scenario can be very large (e.g. about 24 h of serial run simulation time for a 4 h station blackout scenario). Since scenarios leading to system failure are more of interest, a method is proposed for online labeling of scenarios as failure or non-failure. The algorithm first trains a Hidden Markov Model, which represents the behavior of non-failure scenarios, using a training set from previous simulations. Then, the maximum likelihoods of sample failure and non-failure scenarios fitting this model are computed. These values are used to determine the timestamp at which the labeling of a certain scenario should be performed. Finally, during the succeeding timestamps, the likelihood of each scenario fitting the learned model is computed, and a dynamic thresholding based on the previously calculated likelihood values is applied. The scenarios whose likelihood is higher than the threshold are labeled as non-failure. The proposed algorithm can further delay the non-failure scenarios or discontinue them in order to redirect the computational resources toward the failure scenarios, and reduce computational time and complexity. Experiments using RELAP5/3D model of a fast reactor utilizing an Reactor Vessel Auxiliary Cooling System (RVACS) passive decay heat removal system and dynamic analysis of a station blackout (SBO) event show that the proposed method is

  17. Evaluation of temporal surveillance system sensitivity and freedom from bovine viral diarrhea in Danish dairy herds using scenario tree modelling.

    Science.gov (United States)

    Foddai, Alessandro; Stockmarr, Anders; Boklund, Anette

    2016-06-21

    The temporal sensitivity of the surveillance system (TemSSe) for Bovine Viral Diarrhea (BVD) in Danish dairy herds was evaluated. Currently, the Danish antibody blocking ELISA is used to test quarterly bulk tank milk (BTM). To optimize the surveillance system as an early warning system, we considered the possibility of using the SVANOVIR ELISA, as this test has been shown to detect BVD-positive herds earlier than the blocking ELISA in BTM tests. Information from data (2010) and outputs from two published stochastic models were fed into a stochastic scenario tree to estimate the TemSSe. For that purpose we considered: the risk of BVD introduction into the dairy population, the ELISA used and the high risk period (HRP) from BVD introduction to testing (at 90 or 365 days). The effect of introducing one persistently infected (PI) calf or one transiently infected (TI) milking cow into 1 (or 8) dairy herd(s) was investigated. Additionally we estimated the confidence in low (PLow) herd prevalence (tree methodology, could be applied to optimize early warning surveillance systems of different animal diseases.

  18. Thematic and spatial resolutions affect model-based predictions of tree species distribution.

    Science.gov (United States)

    Liang, Yu; He, Hong S; Fraser, Jacob S; Wu, ZhiWei

    2013-01-01

    Subjective decisions of thematic and spatial resolutions in characterizing environmental heterogeneity may affect the characterizations of spatial pattern and the simulation of occurrence and rate of ecological processes, and in turn, model-based tree species distribution. Thus, this study quantified the importance of thematic and spatial resolutions, and their interaction in predictions of tree species distribution (quantified by species abundance). We investigated how model-predicted species abundances changed and whether tree species with different ecological traits (e.g., seed dispersal distance, competitive capacity) had different responses to varying thematic and spatial resolutions. We used the LANDIS forest landscape model to predict tree species distribution at the landscape scale and designed a series of scenarios with different thematic (different numbers of land types) and spatial resolutions combinations, and then statistically examined the differences of species abundance among these scenarios. Results showed that both thematic and spatial resolutions affected model-based predictions of species distribution, but thematic resolution had a greater effect. Species ecological traits affected the predictions. For species with moderate dispersal distance and relatively abundant seed sources, predicted abundance increased as thematic resolution increased. However, for species with long seeding distance or high shade tolerance, thematic resolution had an inverse effect on predicted abundance. When seed sources and dispersal distance were not limiting, the predicted species abundance increased with spatial resolution and vice versa. Results from this study may provide insights into the choice of thematic and spatial resolutions for model-based predictions of tree species distribution.

  19. Constructing Dynamic Event Trees from Markov Models

    International Nuclear Information System (INIS)

    Paolo Bucci; Jason Kirschenbaum; Tunc Aldemir; Curtis Smith; Ted Wood

    2006-01-01

    In the probabilistic risk assessment (PRA) of process plants, Markov models can be used to model accurately the complex dynamic interactions between plant physical process variables (e.g., temperature, pressure, etc.) and the instrumentation and control system that monitors and manages the process. One limitation of this approach that has prevented its use in nuclear power plant PRAs is the difficulty of integrating the results of a Markov analysis into an existing PRA. In this paper, we explore a new approach to the generation of failure scenarios and their compilation into dynamic event trees from a Markov model of the system. These event trees can be integrated into an existing PRA using software tools such as SAPHIRE. To implement our approach, we first construct a discrete-time Markov chain modeling the system of interest by: (a) partitioning the process variable state space into magnitude intervals (cells), (b) using analytical equations or a system simulator to determine the transition probabilities between the cells through the cell-to-cell mapping technique, and, (c) using given failure/repair data for all the components of interest. The Markov transition matrix thus generated can be thought of as a process model describing the stochastic dynamic behavior of the finite-state system. We can therefore search the state space starting from a set of initial states to explore all possible paths to failure (scenarios) with associated probabilities. We can also construct event trees of arbitrary depth by tracing paths from a chosen initiating event and recording the following events while keeping track of the probabilities associated with each branch in the tree. As an example of our approach, we use the simple level control system often used as benchmark in the literature with one process variable (liquid level in a tank), and three control units: a drain unit and two supply units. Each unit includes a separate level sensor to observe the liquid level in the tank

  20. Sequence Tree Modeling for Combined Accident and Feed-and-Bleed Operation

    International Nuclear Information System (INIS)

    Kim, Bo Gyung; Kang Hyun Gook; Yoon, Ho Joon

    2016-01-01

    In order to address this issue, this study suggests the sequence tree model to analyze accident sequence systematically. Using the sequence tree model, all possible scenarios which need a specific safety action to prevent the core damage can be identified and success conditions of safety action under complicated situation such as combined accident will be also identified. Sequence tree is branch model to divide plant condition considering the plant dynamics. Since sequence tree model can reflect the plant dynamics, arising from interaction of different accident timing and plant condition and from the interaction between the operator action, mitigation system, and the indicators for operation, sequence tree model can be used to develop the dynamic event tree model easily. Target safety action for this study is a feed-and-bleed (F and B) operation. A F and B operation directly cools down the reactor cooling system (RCS) using the primary cooling system when residual heat removal by the secondary cooling system is not available. In this study, a TLOFW accident and a TLOFW accident with LOCA were the target accidents. Based on the conventional PSA model and indicators, the sequence tree model for a TLOFW accident was developed. If sampling analysis is performed, practical accident sequences can be identified based on the sequence analysis. If a realistic distribution for the variables can be obtained for sampling analysis, much more realistic accident sequences can be described. Moreover, if the initiating event frequency under a combined accident can be quantified, the sequence tree model can translate into a dynamic event tree model based on the sampling analysis results

  1. Sequence Tree Modeling for Combined Accident and Feed-and-Bleed Operation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bo Gyung; Kang Hyun Gook [KAIST, Daejeon (Korea, Republic of); Yoon, Ho Joon [Khalifa University of Science, Abu Dhabi (United Arab Emirates)

    2016-05-15

    In order to address this issue, this study suggests the sequence tree model to analyze accident sequence systematically. Using the sequence tree model, all possible scenarios which need a specific safety action to prevent the core damage can be identified and success conditions of safety action under complicated situation such as combined accident will be also identified. Sequence tree is branch model to divide plant condition considering the plant dynamics. Since sequence tree model can reflect the plant dynamics, arising from interaction of different accident timing and plant condition and from the interaction between the operator action, mitigation system, and the indicators for operation, sequence tree model can be used to develop the dynamic event tree model easily. Target safety action for this study is a feed-and-bleed (F and B) operation. A F and B operation directly cools down the reactor cooling system (RCS) using the primary cooling system when residual heat removal by the secondary cooling system is not available. In this study, a TLOFW accident and a TLOFW accident with LOCA were the target accidents. Based on the conventional PSA model and indicators, the sequence tree model for a TLOFW accident was developed. If sampling analysis is performed, practical accident sequences can be identified based on the sequence analysis. If a realistic distribution for the variables can be obtained for sampling analysis, much more realistic accident sequences can be described. Moreover, if the initiating event frequency under a combined accident can be quantified, the sequence tree model can translate into a dynamic event tree model based on the sampling analysis results.

  2. A Bayesian Supertree Model for Genome-Wide Species Tree Reconstruction

    Science.gov (United States)

    De Oliveira Martins, Leonardo; Mallo, Diego; Posada, David

    2016-01-01

    Current phylogenomic data sets highlight the need for species tree methods able to deal with several sources of gene tree/species tree incongruence. At the same time, we need to make most use of all available data. Most species tree methods deal with single processes of phylogenetic discordance, namely, gene duplication and loss, incomplete lineage sorting (ILS) or horizontal gene transfer. In this manuscript, we address the problem of species tree inference from multilocus, genome-wide data sets regardless of the presence of gene duplication and loss and ILS therefore without the need to identify orthologs or to use a single individual per species. We do this by extending the idea of Maximum Likelihood (ML) supertrees to a hierarchical Bayesian model where several sources of gene tree/species tree disagreement can be accounted for in a modular manner. We implemented this model in a computer program called guenomu whose inputs are posterior distributions of unrooted gene tree topologies for multiple gene families, and whose output is the posterior distribution of rooted species tree topologies. We conducted extensive simulations to evaluate the performance of our approach in comparison with other species tree approaches able to deal with more than one leaf from the same species. Our method ranked best under simulated data sets, in spite of ignoring branch lengths, and performed well on empirical data, as well as being fast enough to analyze relatively large data sets. Our Bayesian supertree method was also very successful in obtaining better estimates of gene trees, by reducing the uncertainty in their distributions. In addition, our results show that under complex simulation scenarios, gene tree parsimony is also a competitive approach once we consider its speed, in contrast to more sophisticated models. PMID:25281847

  3. A Bayesian Supertree Model for Genome-Wide Species Tree Reconstruction.

    Science.gov (United States)

    De Oliveira Martins, Leonardo; Mallo, Diego; Posada, David

    2016-05-01

    Current phylogenomic data sets highlight the need for species tree methods able to deal with several sources of gene tree/species tree incongruence. At the same time, we need to make most use of all available data. Most species tree methods deal with single processes of phylogenetic discordance, namely, gene duplication and loss, incomplete lineage sorting (ILS) or horizontal gene transfer. In this manuscript, we address the problem of species tree inference from multilocus, genome-wide data sets regardless of the presence of gene duplication and loss and ILS therefore without the need to identify orthologs or to use a single individual per species. We do this by extending the idea of Maximum Likelihood (ML) supertrees to a hierarchical Bayesian model where several sources of gene tree/species tree disagreement can be accounted for in a modular manner. We implemented this model in a computer program called guenomu whose inputs are posterior distributions of unrooted gene tree topologies for multiple gene families, and whose output is the posterior distribution of rooted species tree topologies. We conducted extensive simulations to evaluate the performance of our approach in comparison with other species tree approaches able to deal with more than one leaf from the same species. Our method ranked best under simulated data sets, in spite of ignoring branch lengths, and performed well on empirical data, as well as being fast enough to analyze relatively large data sets. Our Bayesian supertree method was also very successful in obtaining better estimates of gene trees, by reducing the uncertainty in their distributions. In addition, our results show that under complex simulation scenarios, gene tree parsimony is also a competitive approach once we consider its speed, in contrast to more sophisticated models. © The Author(s) 2014. Published by Oxford University Press on behalf of the Society of Systematic Biologists.

  4. Urban tree growth modeling

    Science.gov (United States)

    E. Gregory McPherson; Paula J. Peper

    2012-01-01

    This paper describes three long-term tree growth studies conducted to evaluate tree performance because repeated measurements of the same trees produce critical data for growth model calibration and validation. Several empirical and process-based approaches to modeling tree growth are reviewed. Modeling is more advanced in the fields of forestry and...

  5. Biomass Scenario Model Scenario Library: Definitions, Construction, and Description

    Energy Technology Data Exchange (ETDEWEB)

    Inman, D.; Vimmerstedt, L.; Bush, B.; Peterson, S.

    2014-04-01

    Understanding the development of the biofuels industry in the United States is important to policymakers and industry. The Biomass Scenario Model (BSM) is a system dynamics model of the biomass-to-biofuels system that can be used to explore policy effects on biofuels development. Because of the complexity of the model, as well as the wide range of possible future conditions that affect biofuels industry development, we have not developed a single reference case but instead developed a set of specific scenarios that provide various contexts for our analyses. The purpose of this report is to describe the scenarios that comprise the BSM scenario library. At present, we have the following policy-focused scenarios in our library: minimal policies, ethanol-focused policies, equal access to policies, output-focused policies, technological diversity focused, and the point-of-production- focused. This report describes each scenario, its policy settings, and general insights gained through use of the scenarios in analytic studies.

  6. Evaluation of the cost-effectiveness of bovine brucellosis surveillance in a disease-free country using stochastic scenario tree modelling.

    Directory of Open Access Journals (Sweden)

    Viviane Hénaux

    Full Text Available Surveillance systems of exotic infectious diseases aim to ensure transparency about the country-specific animal disease situation (i.e. demonstrate disease freedom and to identify any introductions. In a context of decreasing resources, evaluation of surveillance efficiency is essential to help stakeholders make relevant decisions about prioritization of measures and funding allocation. This study evaluated the efficiency (sensitivity related to cost of the French bovine brucellosis surveillance system using stochastic scenario tree models. Cattle herds were categorized into three risk groups based on the annual number of purchases, given that trading is considered as the main route of brucellosis introduction in cattle herds. The sensitivity in detecting the disease and the costs of the current surveillance system, which includes clinical (abortion surveillance, programmed serological testing and introduction controls, were compared to those of 19 alternative surveillance scenarios. Surveillance costs included veterinary fees and laboratory analyses. The sensitivity over a year of the current surveillance system was predicted to be 91±7% at a design prevalence of 0.01% for a total cost of 14.9±1.8 million €. Several alternative surveillance scenarios, based on clinical surveillance and random or risk-based serological screening in a sample (20% of the population, were predicted to be at least as sensitive but for a lower cost. Such changes would reduce whole surveillance costs by 20 to 61% annually, and the costs for farmers only would be decreased from about 12.0 million € presently to 5.3-9.0 million € (i.e. 25-56% decrease. Besides, fostering the evolution of the surveillance system in one of these directions would be in agreement with the European regulations and farmers perceptions on brucellosis risk and surveillance.

  7. Evaluation of the cost-effectiveness of bovine brucellosis surveillance in a disease-free country using stochastic scenario tree modelling.

    Science.gov (United States)

    Hénaux, Viviane; Calavas, Didier

    2017-01-01

    Surveillance systems of exotic infectious diseases aim to ensure transparency about the country-specific animal disease situation (i.e. demonstrate disease freedom) and to identify any introductions. In a context of decreasing resources, evaluation of surveillance efficiency is essential to help stakeholders make relevant decisions about prioritization of measures and funding allocation. This study evaluated the efficiency (sensitivity related to cost) of the French bovine brucellosis surveillance system using stochastic scenario tree models. Cattle herds were categorized into three risk groups based on the annual number of purchases, given that trading is considered as the main route of brucellosis introduction in cattle herds. The sensitivity in detecting the disease and the costs of the current surveillance system, which includes clinical (abortion) surveillance, programmed serological testing and introduction controls, were compared to those of 19 alternative surveillance scenarios. Surveillance costs included veterinary fees and laboratory analyses. The sensitivity over a year of the current surveillance system was predicted to be 91±7% at a design prevalence of 0.01% for a total cost of 14.9±1.8 million €. Several alternative surveillance scenarios, based on clinical surveillance and random or risk-based serological screening in a sample (20%) of the population, were predicted to be at least as sensitive but for a lower cost. Such changes would reduce whole surveillance costs by 20 to 61% annually, and the costs for farmers only would be decreased from about 12.0 million € presently to 5.3-9.0 million € (i.e. 25-56% decrease). Besides, fostering the evolution of the surveillance system in one of these directions would be in agreement with the European regulations and farmers perceptions on brucellosis risk and surveillance.

  8. A working definition of scenario and a method of scenario construction

    International Nuclear Information System (INIS)

    Barr, G.E.; Dunn, E.

    1992-01-01

    The event-tree method of scenario construction has been chosen for the Yucca Mountain performance assessment. Its applicability and suitability to the problem are discussed and compared with those of the Nuclear Regulatory Commission (NRC) method. The event-tree method is appropriate for an incompletely characterized site, where there must be an evolving understanding, over time, of the processes at work, for a site that may require analysis of details in specific context, and when the scenario functions to guide site characterization. Anticipating the eventual requirement for using the NRC method, we show that the event-tree method can be translated to the NRC format after final scenario screening

  9. The Scenario Model Intercomparison Project (ScenarioMIP) for CMIP6

    Energy Technology Data Exchange (ETDEWEB)

    O' Neill, Brian C.; Tebaldi, Claudia; van Vuuren, Detlef P.; Eyring, Veronika; Friedlingstein, Pierre; Hurtt, George; Knutti, Reto; Kriegler, Elmar; Lamarque, Jean-Francois; Lowe, Jason; Meehl, Gerald A.; Moss, Richard; Riahi, Keywan; Sanderson, Benjamin M.

    2016-01-01

    Projections of future climate change play a fundamental role in improving understanding of the climate system as well as characterizing societal risks and response options. The Scenario Model Intercomparison Project (ScenarioMIP) is the primary activity within Phase 6 of the Coupled Model Intercomparison Project (CMIP6) that will provide multi-model climate projections based on alternative scenarios of future emissions and land use changes produced with integrated assessment models. In this paper, we describe ScenarioMIP's objectives, experimental design, and its relation to other activities within CMIP6. The ScenarioMIP design is one component of a larger scenario process that aims to facilitate a wide range of integrated studies across the climate science, integrated assessment modeling, and impacts, adaptation, and vulnerability communities, and will form an important part of the evidence base in the forthcoming Intergovernmental Panel on Climate Change (IPCC) assessments. At the same time, it will provide the basis for investigating a number of targeted science and policy questions that are especially relevant to scenario-based analysis, including the role of specific forcings such as land use and aerosols, the effect of a peak and decline in forcing, the consequences of scenarios that limit warming to below 2 °C, the relative contributions to uncertainty from scenarios, climate models, and internal variability, and long-term climate system outcomes beyond the 21st century. To serve this wide range of scientific communities and address these questions, a design has been identified consisting of eight alternative 21st century scenarios plus one large initial condition ensemble and a set of long-term extensions, divided into two tiers defined by relative priority. Some of these scenarios will also provide a basis for variants planned to be run in other CMIP6-Endorsed MIPs to investigate questions related to specific forcings. Harmonized, spatially

  10. Different intra- and interspecific facilitation mechanisms between two Mediterranean trees under a climate change scenario.

    Science.gov (United States)

    Gimeno, Teresa E; Escudero, Adrián; Valladares, Fernando

    2015-01-01

    In harsh environments facilitation alleviates biotic and abiotic constraints on tree recruitment. Under ongoing drier climate change, we expect facilitation to increase as a driver of coexistence. However, this might not hold under extreme abiotic stress and when the outcome depends on the interaction with other drivers such as altered herbivore pressure due to land use change. We performed a field water-manipulation experiment to quantify the importance of facilitation in two coexisting Mediterranean trees (dominant Juniperus thurifera and coexisting Quercus ilex subsp. ballota) under a climate change scenario. Shifts in canopy dominance favouring Q. ilex could be based on the extension of heterospecific facilitation to the detriment of conspecific alleviation. We found that saplings of both species transplanted under the canopy of nurse trees had greater survival probability, growth and photochemical efficiency. Intra- and interspecific facilitation mechanisms differed: alleviation of abiotic stress benefited both species during summer and J. thurifera during winter, whereas browsing protection was relevant only for Q. ilex. Facilitation was greater under the dry treatment only for Q. ilex, which partially agreed with the predictions of the stress gradient hypothesis. We conclude that present rainfall availability limits neither J. thurifera nor Q. ilex establishment. Nevertheless, under current global change scenarios, imposing increasing abiotic stress together with altered herbivore browsing, nurse trees could differentially facilitate the establishment of Q. ilex due to species-specific traits, i.e. palatability; drought, heat and cold tolerance, underlying species differences in the facilitation mechanisms and eventually triggering a change from pure juniper woodlands to mixed formations.

  11. Biophysical modelling of intra-ring variations in tracheid features and wood density of Pinus pinaster trees exposed to seasonal droughts

    Science.gov (United States)

    Sarah Wilkinson; Jerome Ogee; Jean-Christophe Domec; Mark Rayment; Lisa Wingate

    2015-01-01

    Process-based models that link seasonally varying environmental signals to morphological features within tree rings are essential tools to predict tree growth response and commercially important wood quality traits under future climate scenarios. This study evaluated model portrayal of radial growth and wood anatomy observations within a mature maritime pine (Pinus...

  12. A Model for the Detailed Analysis of Radio Links Involving Tree Canopies

    Directory of Open Access Journals (Sweden)

    F. Perez-Fontan

    2016-12-01

    Full Text Available Detailed analysis of tree canopy interaction with incident radiowaves has mainly been limited to remote sensing for the purpose of forest classification among many other applications. This represents a monostatic configuration, unlike the case of communication links, which are bistatic. In general, link analyses have been limited to the application of simple, empirical formulas based on the use of specific attenuation values in dB/m and the traversed vegetated mass as, e.g., the model in Recommendation ITU-R P.833-8 [1]. In remote sensing, two main techniques are used: Multiple Scattering Theory (MST [2][5] and Radiative Transfer Theory (RT, [5] and [6]. We have paid attention in the past to MST [7][10]. It was shown that a full application of MST leads to very long computation times which are unacceptable in the case where we have to analyze a scenario with several trees. Extensive work using MST has been also presented by others in [11][16] showing the interest in this technique. We have proposed a simplified model for scattering from tree canopies based on a hybridization of MST and a modified physical optics (PO approach [16]. We assume that propagation through a canopy is accounted for by using the complex valued propagation constant obtained by MST. Unlike the case when the full MST is applied, the proposed approach offers significant benefits including a direct software implementation and acceptable computation times even for high frequencies and electrically large canopies. The proposed model thus replaces the coherent component in MST, significant in the forward direction, but keeps the incoherent or diffuse scattering component present in all directions. The incoherent component can be calculated within reasonable times. Here, we present tests of the proposed model against MST using an artificial single-tree scenario at 2 GHz and 10 GHz.

  13. Development of a CFD Model Including Tree's Drag Parameterizations: Application to Pedestrian's Wind Comfort in an Urban Area

    Science.gov (United States)

    Kang, G.; Kim, J.

    2017-12-01

    This study investigated the tree's effect on wind comfort at pedestrian height in an urban area using a computational fluid dynamics (CFD) model. We implemented the tree's drag parameterization scheme to the CFD model and validated the simulated results against the wind-tunnel measurement data as well as LES data via several statistical methods. The CFD model underestimated (overestimated) the concentrations on the leeward (windward) walls inside the street canyon in the presence of trees, because the CFD model can't resolve the latticed cage and can't reflect the concentration increase and decrease caused by the latticed cage in the simulations. However, the scalar pollutants' dispersion simulated by the CFD model was quite similar to that in the wind-tunnel measurement in pattern and magnitude, on the whole. The CFD model overall satisfied the statistical validation indices (root normalized mean square error, geometric mean variance, correlation coefficient, and FAC2) but failed to satisfy the fractional bias and geometric mean bias due to the underestimation on the leeward wall and overestimation on the windward wall, showing that its performance was comparable to the LES's performance. We applied the CFD model to evaluation of the trees' effect on the pedestrian's wind-comfort in an urban area. To investigate sensory levels for human activities, the wind-comfort criteria based on Beaufort wind-force scales (BWSs) were used. In the tree-free scenario, BWS 4 and 5 (unpleasant condition for sitting long and sitting short, respectively) appeared in the narrow spaces between buildings, in the upwind side of buildings, and the unobstructed areas. In the tree scenario, BWSs decreased by 1 3 grade inside the campus of Pukyong National University located in the target area, which indicated that trees planted in the campus effectively improved pedestrian's wind comfort.

  14. [Effects of sampling plot number on tree species distribution prediction under climate change].

    Science.gov (United States)

    Liang, Yu; He, Hong-Shi; Wu, Zhi-Wei; Li, Xiao-Na; Luo, Xu

    2013-05-01

    Based on the neutral landscapes under different degrees of landscape fragmentation, this paper studied the effects of sampling plot number on the prediction of tree species distribution at landscape scale under climate change. The tree species distribution was predicted by the coupled modeling approach which linked an ecosystem process model with a forest landscape model, and three contingent scenarios and one reference scenario of sampling plot numbers were assumed. The differences between the three scenarios and the reference scenario under different degrees of landscape fragmentation were tested. The results indicated that the effects of sampling plot number on the prediction of tree species distribution depended on the tree species life history attributes. For the generalist species, the prediction of their distribution at landscape scale needed more plots. Except for the extreme specialist, landscape fragmentation degree also affected the effects of sampling plot number on the prediction. With the increase of simulation period, the effects of sampling plot number on the prediction of tree species distribution at landscape scale could be changed. For generalist species, more plots are needed for the long-term simulation.

  15. Biomass Scenario Model | Energy Analysis | NREL

    Science.gov (United States)

    Biomass Scenario Model Biomass Scenario Model The Biomass Scenario Model (BSM) is a unique range of lignocellulosic biomass feedstocks into biofuels. Over the past 25 years, the corn ethanol plant matter (lignocellulosic biomass) to fermentable sugars for the production of fuel ethanol

  16. Modelling tree biomasses in Finland

    Energy Technology Data Exchange (ETDEWEB)

    Repola, J.

    2013-06-01

    Biomass equations for above- and below-ground tree components of Scots pine (Pinus sylvestris L), Norway spruce (Picea abies [L.] Karst) and birch (Betula pendula Roth and Betula pubescens Ehrh.) were compiled using empirical material from a total of 102 stands. These stands (44 Scots pine, 34 Norway spruce and 24 birch stands) were located mainly on mineral soil sites representing a large part of Finland. The biomass models were based on data measured from 1648 sample trees, comprising 908 pine, 613 spruce and 127 birch trees. Biomass equations were derived for the total above-ground biomass and for the individual tree components: stem wood, stem bark, living and dead branches, needles, stump, and roots, as dependent variables. Three multivariate models with different numbers of independent variables for above-ground biomass and one for below-ground biomass were constructed. Variables that are normally measured in forest inventories were used as independent variables. The simplest model formulations, multivariate models (1) were mainly based on tree diameter and height as independent variables. In more elaborated multivariate models, (2) and (3), additional commonly measured tree variables such as age, crown length, bark thickness and radial growth rate were added. Tree biomass modelling includes consecutive phases, which cause unreliability in the prediction of biomass. First, biomasses of sample trees should be determined reliably to decrease the statistical errors caused by sub-sampling. In this study, methods to improve the accuracy of stem biomass estimates of the sample trees were developed. In addition, the reliability of the method applied to estimate sample-tree crown biomass was tested, and no systematic error was detected. Second, the whole information content of data should be utilized in order to achieve reliable parameter estimates and applicable and flexible model structure. In the modelling approach, the basic assumption was that the biomasses of

  17. DAG-based attack and defense modeling: don’t miss the forest for the attack trees

    NARCIS (Netherlands)

    Kordy, Barbara; Piètre-Cambacédès, Ludovic; Schweitzer, Patrick

    2015-01-01

    This paper presents the current state of the art on attack and defense modeling approaches that are based on directed acyclic graphs (DAGs). DAGs allow for a hierarchical decomposition of complex scenarios into simple, easily understandable and quantifiable actions. Methods based on threat trees and

  18. Process Risk Assessment using Dynamic Simulation of Scenarios

    DEFF Research Database (Denmark)

    Markert, Frank; Kozin, Igor; Duijm, Nijs Jan

    2016-01-01

    identification, description of accident scenarios and using the conventional approach to develop static event trees for events following a loss of containment. Modelling the impacts and consequences needs models to describe the release, dispersion and effect of the hazardous material, as well as models...

  19. Model checking exact cost for attack scenarios

    DEFF Research Database (Denmark)

    Aslanyan, Zaruhi; Nielson, Flemming

    2017-01-01

    Attack trees constitute a powerful tool for modelling security threats. Many security analyses of attack trees can be seamlessly expressed as model checking of Markov Decision Processes obtained from the attack trees, thus reaping the benefits of a coherent framework and a mature tool support....... However, current model checking does not encompass the exact cost analysis of an attack, which is standard for attack trees. Our first contribution is the logic erPCTL with cost-related operators. The extended logic allows to analyse the probability of an event satisfying given cost bounds and to compute...... the exact cost of an event. Our second contribution is the model checking algorithm for erPCTL. Finally, we apply our framework to the analysis of attack trees....

  20. Assessing the Cooling Benefits of Tree Shade by an Outdoor Urban Physical Scale Model at Tempe, AZ

    Directory of Open Access Journals (Sweden)

    Qunshan Zhao

    2018-01-01

    Full Text Available Urban green infrastructure, especially shade trees, offers benefits to the urban residential environment by mitigating direct incoming solar radiation on building facades, particularly in hot settings. Understanding the impact of different tree locations and arrangements around residential properties has the potential to maximize cooling and can ultimately guide urban planners, designers, and homeowners on how to create the most sustainable urban environment. This research measures the cooling effect of tree shade on building facades through an outdoor urban physical scale model. The physical scale model is a simulated neighborhood consisting of an array of concrete cubes to represent houses with identical artificial trees. We tested and compared 10 different tree densities, locations, and arrangement scenarios in the physical scale model. The experimental results show that a single tree located at the southeast of the building can provide up to 2.3 °C hourly cooling benefits to east facade of the building. A two-tree cluster arrangement provides more cooling benefits (up to 6.6 °C hourly cooling benefits to the central facade when trees are located near the south and southeast sides of the building. The research results confirm the cooling benefits of tree shade and the importance of wisely designing tree locations and arrangements in the built environment.

  1. Learning in data-limited multimodal scenarios: Scandent decision forests and tree-based features.

    Science.gov (United States)

    Hor, Soheil; Moradi, Mehdi

    2016-12-01

    Incomplete and inconsistent datasets often pose difficulties in multimodal studies. We introduce the concept of scandent decision trees to tackle these difficulties. Scandent trees are decision trees that optimally mimic the partitioning of the data determined by another decision tree, and crucially, use only a subset of the feature set. We show how scandent trees can be used to enhance the performance of decision forests trained on a small number of multimodal samples when we have access to larger datasets with vastly incomplete feature sets. Additionally, we introduce the concept of tree-based feature transforms in the decision forest paradigm. When combined with scandent trees, the tree-based feature transforms enable us to train a classifier on a rich multimodal dataset, and use it to classify samples with only a subset of features of the training data. Using this methodology, we build a model trained on MRI and PET images of the ADNI dataset, and then test it on cases with only MRI data. We show that this is significantly more effective in staging of cognitive impairments compared to a similar decision forest model trained and tested on MRI only, or one that uses other kinds of feature transform applied to the MRI data. Copyright © 2016. Published by Elsevier B.V.

  2. Automated Generation of Attack Trees

    DEFF Research Database (Denmark)

    Vigo, Roberto; Nielson, Flemming; Nielson, Hanne Riis

    2014-01-01

    Attack trees are widely used to represent threat scenarios in a succinct and intuitive manner, suitable for conveying security information to non-experts. The manual construction of such objects relies on the creativity and experience of specialists, and therefore it is error-prone and impractica......Attack trees are widely used to represent threat scenarios in a succinct and intuitive manner, suitable for conveying security information to non-experts. The manual construction of such objects relies on the creativity and experience of specialists, and therefore it is error......-prone and impracticable for large systems. Nonetheless, the automated generation of attack trees has only been explored in connection to computer networks and levering rich models, whose analysis typically leads to an exponential blow-up of the state space. We propose a static analysis approach where attack trees...... are automatically inferred from a process algebraic specification in a syntax-directed fashion, encompassing a great many application domains and avoiding incurring systematically an exponential explosion. Moreover, we show how the standard propositional denotation of an attack tree can be used to phrase...

  3. Fault tree analysis of loss of cooling to a HALW storage tank

    International Nuclear Information System (INIS)

    Nomura, Yasushi

    1992-01-01

    Results of a scenario identification, a fault tree construction and an analysis for a loss of cooling accident in a High Activity Liquid Waste (HALW) tank of a typical model of reprocessing facility, is rendered together with considerations of the system reliability improvement by changing the model design. Model plant data, basic failure frequency data and a fault tree analysis named FTL have been introduced from NUKEM GmbH, Germany. They are throughly reviewed and reevaluated at JAERI, and improved to apply to Japanese facilities. A general systematic method for constructing fault trees is used to avoid missing scenarios, thus all of the 10 conceivable accident scenarios for 'HALW storage tank without cooling, HALW boiling' are identified, and a total failure frequency are calculated to be in the 90 % confidence interval of (1.1 ∼ 5.8) x 10 -6 /yr for the German model plant. (author)

  4. Structural Equation Model Trees

    Science.gov (United States)

    Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman

    2013-01-01

    In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree…

  5. SCENARIO OF AN ACCIDENT OF SOIL DAMS IN CASE OF WATER SPILL OVER A DAM CREST BY USING FAULT TREE ANALYSIS

    OpenAIRE

    Kuznetsov Dmitriy Viktorovich

    2016-01-01

    The scenario of a hydrodynamic accident of water flow over a crest of a soil dam is considered by the method of fault tree analysis, for which the basic reasons and controlled diagnostic indicators of an accident have been defined. Logical operators “AND”/”OR” were used for creation of a sequence of logically connected events, leading to an undesired event in the scenario of accident. The scenario of the accident was plotted in case of three basic reasons - an excessive settling of a dam cres...

  6. A model for the inverse 1-median problem on trees under uncertain costs

    Directory of Open Access Journals (Sweden)

    Kien Trung Nguyen

    2016-01-01

    Full Text Available We consider the problem of justifying vertex weights of a tree under uncertain costs so that a prespecified vertex become optimal and the total cost should be optimal in the uncertainty scenario. We propose a model which delivers the information about the optimal cost which respect to each confidence level \\(\\alpha \\in [0,1]\\. To obtain this goal, we first define an uncertain variable with respect to the minimum cost in each confidence level. If all costs are independently linear distributed, we present the inverse distribution function of this uncertain variable in \\(O(n^{2}\\log n\\ time, where \\(n\\ is the number of vertices in the tree.

  7. Real-Time Flood Control by Tree-Based Model Predictive Control Including Forecast Uncertainty: A Case Study Reservoir in Turkey

    Directory of Open Access Journals (Sweden)

    Gökçen Uysal

    2018-03-01

    Full Text Available Optimal control of reservoirs is a challenging task due to conflicting objectives, complex system structure, and uncertainties in the system. Real time control decisions suffer from streamflow forecast uncertainty. This study aims to use Probabilistic Streamflow Forecasts (PSFs having a lead-time up to 48 h as input for the recurrent reservoir operation problem. A related technique for decision making is multi-stage stochastic optimization using scenario trees, referred to as Tree-based Model Predictive Control (TB-MPC. Deterministic Streamflow Forecasts (DSFs are provided by applying random perturbations on perfect data. PSFs are synthetically generated from DSFs by a new approach which explicitly presents dynamic uncertainty evolution. We assessed different variables in the generation of stochasticity and compared the results using different scenarios. The developed real-time hourly flood control was applied to a test case which had limited reservoir storage and restricted downstream condition. According to hindcasting closed-loop experiment results, TB-MPC outperforms the deterministic counterpart in terms of decreased downstream flood risk according to different independent forecast scenarios. TB-MPC was also tested considering different number of tree branches, forecast horizons, and different inflow conditions. We conclude that using synthetic PSFs in TB-MPC can provide more robust solutions against forecast uncertainty by resolution of uncertainty in trees.

  8. Reconciliation of Gene and Species Trees

    Directory of Open Access Journals (Sweden)

    L. Y. Rusin

    2014-01-01

    Full Text Available The first part of the paper briefly overviews the problem of gene and species trees reconciliation with the focus on defining and algorithmic construction of the evolutionary scenario. Basic ideas are discussed for the aspects of mapping definitions, costs of the mapping and evolutionary scenario, imposing time scales on a scenario, incorporating horizontal gene transfers, binarization and reconciliation of polytomous trees, and construction of species trees and scenarios. The review does not intend to cover the vast diversity of literature published on these subjects. Instead, the authors strived to overview the problem of the evolutionary scenario as a central concept in many areas of evolutionary research. The second part provides detailed mathematical proofs for the solutions of two problems: (i inferring a gene evolution along a species tree accounting for various types of evolutionary events and (ii trees reconciliation into a single species tree when only gene duplications and losses are allowed. All proposed algorithms have a cubic time complexity and are mathematically proved to find exact solutions. Solving algorithms for problem (ii can be naturally extended to incorporate horizontal transfers, other evolutionary events, and time scales on the species tree.

  9. Current and Future Distribution of the Tropical Tree Cedrela odorata L. in Mexico under Climate Change Scenarios Using MaxLike

    Science.gov (United States)

    Martínez Meyer, Enrique; Sánchez-Velásquez, Lázaro R.

    2016-01-01

    Climate change is recognized as an important threat to global biodiversity because it increases the risk of extinction of many species on the planet. Mexico is a megadiverse country and native tree species such as red cedar (Cedrela odorata) can be used to maintain forests while helping mitigate climate change, because it is considered a fast growing pioneer species with great economic potential in the forestry industry. In order to assess possible shifts in areas suitable for C. odorata plantations in Mexico with ecological niche models, we used the MaxLike algorithm, climate variables, the geo-referenced records of this species, three general circulation models and three scenarios of future emissions. Results show a current potential distribution of 573,079 km2 with an average probability of occurrence of 0.93 (± 0.13). The potential distribution area could increase up to 650,356 km2 by 2060 according to the general circulation model HADCM3 B2, with an average probability of occurrence of 0.86 (± 0.14). Finally, we delimited an area of 35,377 km2 that has a high potential for the establishment of C. odorata plantations, by selecting those sites with optimal conditions for its growth that are outside protected areas and are currently devoid of trees. C. odorata has a significant potential to help in the mitigation of the effects of climate change. Using MaxLike we identified extense areas in Mexico suitable to increase carbon sequestration through plantations of this highly valued native tree species. PMID:27732622

  10. Current and Future Distribution of the Tropical Tree Cedrela odorata L. in Mexico under Climate Change Scenarios Using MaxLike.

    Science.gov (United States)

    Estrada-Contreras, Israel; Equihua, Miguel; Laborde, Javier; Martínez Meyer, Enrique; Sánchez-Velásquez, Lázaro R

    2016-01-01

    Climate change is recognized as an important threat to global biodiversity because it increases the risk of extinction of many species on the planet. Mexico is a megadiverse country and native tree species such as red cedar (Cedrela odorata) can be used to maintain forests while helping mitigate climate change, because it is considered a fast growing pioneer species with great economic potential in the forestry industry. In order to assess possible shifts in areas suitable for C. odorata plantations in Mexico with ecological niche models, we used the MaxLike algorithm, climate variables, the geo-referenced records of this species, three general circulation models and three scenarios of future emissions. Results show a current potential distribution of 573,079 km2 with an average probability of occurrence of 0.93 (± 0.13). The potential distribution area could increase up to 650,356 km2 by 2060 according to the general circulation model HADCM3 B2, with an average probability of occurrence of 0.86 (± 0.14). Finally, we delimited an area of 35,377 km2 that has a high potential for the establishment of C. odorata plantations, by selecting those sites with optimal conditions for its growth that are outside protected areas and are currently devoid of trees. C. odorata has a significant potential to help in the mitigation of the effects of climate change. Using MaxLike we identified extense areas in Mexico suitable to increase carbon sequestration through plantations of this highly valued native tree species.

  11. Current and Future Distribution of the Tropical Tree Cedrela odorata L. in Mexico under Climate Change Scenarios Using MaxLike.

    Directory of Open Access Journals (Sweden)

    Israel Estrada-Contreras

    Full Text Available Climate change is recognized as an important threat to global biodiversity because it increases the risk of extinction of many species on the planet. Mexico is a megadiverse country and native tree species such as red cedar (Cedrela odorata can be used to maintain forests while helping mitigate climate change, because it is considered a fast growing pioneer species with great economic potential in the forestry industry. In order to assess possible shifts in areas suitable for C. odorata plantations in Mexico with ecological niche models, we used the MaxLike algorithm, climate variables, the geo-referenced records of this species, three general circulation models and three scenarios of future emissions. Results show a current potential distribution of 573,079 km2 with an average probability of occurrence of 0.93 (± 0.13. The potential distribution area could increase up to 650,356 km2 by 2060 according to the general circulation model HADCM3 B2, with an average probability of occurrence of 0.86 (± 0.14. Finally, we delimited an area of 35,377 km2 that has a high potential for the establishment of C. odorata plantations, by selecting those sites with optimal conditions for its growth that are outside protected areas and are currently devoid of trees. C. odorata has a significant potential to help in the mitigation of the effects of climate change. Using MaxLike we identified extense areas in Mexico suitable to increase carbon sequestration through plantations of this highly valued native tree species.

  12. Decision tree modeling using R.

    Science.gov (United States)

    Zhang, Zhongheng

    2016-08-01

    In machine learning field, decision tree learner is powerful and easy to interpret. It employs recursive binary partitioning algorithm that splits the sample in partitioning variable with the strongest association with the response variable. The process continues until some stopping criteria are met. In the example I focus on conditional inference tree, which incorporates tree-structured regression models into conditional inference procedures. While growing a single tree is subject to small changes in the training data, random forests procedure is introduced to address this problem. The sources of diversity for random forests come from the random sampling and restricted set of input variables to be selected. Finally, I introduce R functions to perform model based recursive partitioning. This method incorporates recursive partitioning into conventional parametric model building.

  13. Disentangling the Effects of Water Stress on Carbon Acquisition, Vegetative Growth, and Fruit Quality of Peach Trees by Means of the QualiTree Model

    Directory of Open Access Journals (Sweden)

    Mitra Rahmati

    2018-01-01

    its sink strength, and; secondly, through an indirect reducing effect on photosynthesis. Fruit composition was moderately affected by water stress. The enhancements performed in the model broadened its predictive capabilities and proved that QualiTree allows for a better understanding of the water stress effects on fruit-tree functioning and might be useful for designing innovative horticultural practices in a changing climate scenario.

  14. Disentangling the Effects of Water Stress on Carbon Acquisition, Vegetative Growth, and Fruit Quality of Peach Trees by Means of the QualiTree Model.

    Science.gov (United States)

    Rahmati, Mitra; Mirás-Avalos, José M; Valsesia, Pierre; Lescourret, Françoise; Génard, Michel; Davarynejad, Gholam H; Bannayan, Mohammad; Azizi, Majid; Vercambre, Gilles

    2018-01-01

    , and; secondly, through an indirect reducing effect on photosynthesis. Fruit composition was moderately affected by water stress. The enhancements performed in the model broadened its predictive capabilities and proved that QualiTree allows for a better understanding of the water stress effects on fruit-tree functioning and might be useful for designing innovative horticultural practices in a changing climate scenario.

  15. Paleoflood Data, Extreme Floods and Frequency: Data and Models for Dam Safety Risk Scenarios

    Science.gov (United States)

    England, J. F.; Godaire, J.; Klinger, R.

    2007-12-01

    Extreme floods and probability estimates are crucial components in dam safety risk analysis and scenarios for water-resources decision making. The field-based collection of paleoflood data provides needed information on the magnitude and probability of extreme floods at locations of interest in a watershed or region. The stratigraphic record present along streams in the form of terrace and floodplain deposits represent direct indicators of the magnitude of large floods on a river, and may provide 10 to 100 times longer records than conventional stream gaging records of large floods. Paleoflood data is combined with gage and historical streamflow estimates to gain insights to flood frequency scaling, model extrapolations and uncertainty, and provide input scenarios to risk analysis event trees. We illustrate current data collection and flood frequency modeling approaches via case studies in the western United States, including the American River in California and the Arkansas River in Colorado. These studies demonstrate the integration of applied field geology, hydraulics, and surface-water hydrology. Results from these studies illustrate the gains in information content on extreme floods, provide data- based means to separate flood generation processes, guide flood frequency model extrapolations, and reduce uncertainties. These data and scenarios strongly influence water resources management decisions.

  16. Comprehensive decision tree models in bioinformatics.

    Directory of Open Access Journals (Sweden)

    Gregor Stiglic

    Full Text Available PURPOSE: Classification is an important and widely used machine learning technique in bioinformatics. Researchers and other end-users of machine learning software often prefer to work with comprehensible models where knowledge extraction and explanation of reasoning behind the classification model are possible. METHODS: This paper presents an extension to an existing machine learning environment and a study on visual tuning of decision tree classifiers. The motivation for this research comes from the need to build effective and easily interpretable decision tree models by so called one-button data mining approach where no parameter tuning is needed. To avoid bias in classification, no classification performance measure is used during the tuning of the model that is constrained exclusively by the dimensions of the produced decision tree. RESULTS: The proposed visual tuning of decision trees was evaluated on 40 datasets containing classical machine learning problems and 31 datasets from the field of bioinformatics. Although we did not expected significant differences in classification performance, the results demonstrate a significant increase of accuracy in less complex visually tuned decision trees. In contrast to classical machine learning benchmarking datasets, we observe higher accuracy gains in bioinformatics datasets. Additionally, a user study was carried out to confirm the assumption that the tree tuning times are significantly lower for the proposed method in comparison to manual tuning of the decision tree. CONCLUSIONS: The empirical results demonstrate that by building simple models constrained by predefined visual boundaries, one not only achieves good comprehensibility, but also very good classification performance that does not differ from usually more complex models built using default settings of the classical decision tree algorithm. In addition, our study demonstrates the suitability of visually tuned decision trees for datasets

  17. Comprehensive decision tree models in bioinformatics.

    Science.gov (United States)

    Stiglic, Gregor; Kocbek, Simon; Pernek, Igor; Kokol, Peter

    2012-01-01

    Classification is an important and widely used machine learning technique in bioinformatics. Researchers and other end-users of machine learning software often prefer to work with comprehensible models where knowledge extraction and explanation of reasoning behind the classification model are possible. This paper presents an extension to an existing machine learning environment and a study on visual tuning of decision tree classifiers. The motivation for this research comes from the need to build effective and easily interpretable decision tree models by so called one-button data mining approach where no parameter tuning is needed. To avoid bias in classification, no classification performance measure is used during the tuning of the model that is constrained exclusively by the dimensions of the produced decision tree. The proposed visual tuning of decision trees was evaluated on 40 datasets containing classical machine learning problems and 31 datasets from the field of bioinformatics. Although we did not expected significant differences in classification performance, the results demonstrate a significant increase of accuracy in less complex visually tuned decision trees. In contrast to classical machine learning benchmarking datasets, we observe higher accuracy gains in bioinformatics datasets. Additionally, a user study was carried out to confirm the assumption that the tree tuning times are significantly lower for the proposed method in comparison to manual tuning of the decision tree. The empirical results demonstrate that by building simple models constrained by predefined visual boundaries, one not only achieves good comprehensibility, but also very good classification performance that does not differ from usually more complex models built using default settings of the classical decision tree algorithm. In addition, our study demonstrates the suitability of visually tuned decision trees for datasets with binary class attributes and a high number of possibly

  18. Italian energy scenarios: Markal model

    International Nuclear Information System (INIS)

    Gracceva, Francesco

    2005-01-01

    Energy scenarios carried out through formal models comply with scientific criteria such as internal coherence and transparency. Besides, Markal methodology allows a good understanding of the complex nature of the energy system. The business-as-usual scenario carried out through the Markal-Italy model shows that structural changes occurring in end-use sectors will continue to drive up energy consumption, in spite of the slow economic growth and the quite high energy prices [it

  19. Development on quantitative safety analysis method of accident scenario. The automatic scenario generator development for event sequence construction of accident

    International Nuclear Information System (INIS)

    Kojima, Shigeo; Onoue, Akira; Kawai, Katsunori

    1998-01-01

    This study intends to develop a more sophisticated tool that will advance the current event tree method used in all PSA, and to focus on non-catastrophic events, specifically a non-core melt sequence scenario not included in an ordinary PSA. In the non-catastrophic event PSA, it is necessary to consider various end states and failure combinations for the purpose of multiple scenario construction. Therefore it is anticipated that an analysis work should be reduced and automated method and tool is required. A scenario generator that can automatically handle scenario construction logic and generate the enormous size of sequences logically identified by state-of-the-art methodology was developed. To fulfill the scenario generation as a technical tool, a simulation model associated with AI technique and graphical interface, was introduced. The AI simulation model in this study was verified for the feasibility of its capability to evaluate actual systems. In this feasibility study, a spurious SI signal was selected to test the model's applicability. As a result, the basic capability of the scenario generator could be demonstrated and important scenarios were generated. The human interface with a system and its operation, as well as time dependent factors and their quantification in scenario modeling, was added utilizing human scenario generator concept. Then the feasibility of an improved scenario generator was tested for actual use. Automatic scenario generation with a certain level of credibility, was achieved by this study. (author)

  20. Disruption scenarios for a nuclear-waste repository on the Nevada Test Site

    International Nuclear Information System (INIS)

    Link, R.L.; Bingham, F.W.; Barr, G.E.

    1981-01-01

    Scenarios are being constructed for the release of radioactive maerial from hypothetical repositories in different types of rock at NTS. Deductive event trees are constructed; each path through an event tree is a scenario. The complete set of NTS event trees comprises about 340 scenarios, not counting the multiple paths through the subtrees made by expanding complex events. Each of these scenarios is being analyzed for 10 different types of rocks

  1. Modelling the role of nitrogen in acidification of Swedish lakes: future scenarios of acid deposition, climate change and forestry practices

    Energy Technology Data Exchange (ETDEWEB)

    Moldan, Filip (Swedish Environmental Research Institute Ltd., Stockholm (Sweden)); Cosby, B. Jack (Dept. of Env. Sciences, Univ. of Virginia, Charlottesville, VA (United States)); Wright, Richard F. (Norwegian Inst. for Water Research, Kjelsas, Oslo (Norway))

    2009-12-15

    There are three major drivers that can cause future changes in lake water chemistry: air pollution, land use and climate change. In this report we used an extensive set of Swedish lakes sampled in 1995, 2000 and in 2005 to model future lake water chemistry under 5 different scenarios. The base case scenario represented deposition of air pollutants under current legislation (CLE); that is assuming that emissions of sulphur (S) and nitrogen (N) will be reduced as currently agreed by the Gothenburg protocol, NEC directive and other legislation. After the agreed emission reductions were achieved, no further reduction in deposition was assumed and deposition was maintained constant up to year 2100. The base scenario assumed no change in current forestry practices and no climate change. A second other deposition scenario was based on maximum (technically) feasible emission reduction (MFR). The MFR scenario also did not assume change of either forestry practices or climate. A maximum biomass harvest was modelled (land use, LU, scenario), which entailed harvest of tree stems, slash and stumps. A scenario of climate change (CC) followed the IPCC A2 scenario downscaled to Sweden by SMHI. Finally climate change and land use were combined (CCLU scenario). The CC, LU and CCLU scenarios were driven by the 'current legislation' (CLE) deposition scenario for S and N deposition. The biogeochemical model MAGIC was used in this project, and scenarios were evaluated up to year 2100. Special attention was paid to the impact of the future scenarios on N leaching

  2. Finiteness results for Abelian tree models

    NARCIS (Netherlands)

    Draisma, J.; Eggermont, R.H.

    2015-01-01

    Equivariant tree models are statistical models used in the reconstruction of phylogenetic trees from genetic data. Here equivariant refers to a symmetry group imposed on the root distribution and on the transition matrices in the model. We prove that if that symmetry group is Abelian, then the

  3. Finiteness results for Abelian tree models

    NARCIS (Netherlands)

    Draisma, J.; Eggermont, R.H.

    2012-01-01

    Equivariant tree models are statistical models used in the reconstruction of phylogenetic trees from genetic data. Here equivariant refers to a symmetry group imposed on the root distribution and on the transition matrices in the model. We prove that if that symmetry group is Abelian, then the

  4. Finiteness results for Abelian tree models

    NARCIS (Netherlands)

    Draisma, J.; Eggermont, R.H.

    2015-01-01

    Equivariant tree models are statistical models used in the reconstruction of phylogenetic trees from genetic data. Here equivariant§ refers to a symmetry group imposed on the root distribution and on the transition matrices in the model. We prove that if that symmetry group is Abelian, then the

  5. Interactive wood combustion for botanical tree models

    KAUST Repository

    Pirk, Sören

    2017-11-22

    We present a novel method for the combustion of botanical tree models. Tree models are represented as connected particles for the branching structure and a polygonal surface mesh for the combustion. Each particle stores biological and physical attributes that drive the kinetic behavior of a plant and the exothermic reaction of the combustion. Coupled with realistic physics for rods, the particles enable dynamic branch motions. We model material properties, such as moisture and charring behavior, and associate them with individual particles. The combustion is efficiently processed in the surface domain of the tree model on a polygonal mesh. A user can dynamically interact with the model by initiating fires and by inducing stress on branches. The flames realistically propagate through the tree model by consuming the available resources. Our method runs at interactive rates and supports multiple tree instances in parallel. We demonstrate the effectiveness of our approach through numerous examples and evaluate its plausibility against the combustion of real wood samples.

  6. Climatic changes lead to declining winter chill for fruit and nut trees in California during 1950-2099.

    Science.gov (United States)

    Luedeling, Eike; Zhang, Minghua; Girvetz, Evan H

    2009-07-16

    Winter chill is one of the defining characteristics of a location's suitability for the production of many tree crops. We mapped and investigated observed historic and projected future changes in winter chill in California, quantified with two different chilling models (Chilling Hours, Dynamic Model). Based on hourly and daily temperature records, winter chill was modeled for two past temperature scenarios (1950 and 2000), and 18 future scenarios (average conditions during 2041-2060 and 2080-2099 under each of the B1, A1B and A2 IPCC greenhouse gas emissions scenarios, for the CSIRO-MK3, HadCM3 and MIROC climate models). For each scenario, 100 replications of the yearly temperature record were produced, using a stochastic weather generator. We then introduced and mapped a novel climatic statistic, "safe winter chill", the 10% quantile of the resulting chilling distributions. This metric can be interpreted as the amount of chilling that growers can safely expect under each scenario. Winter chill declined substantially for all emissions scenarios, with the area of safe winter chill for many tree species or cultivars decreasing 50-75% by mid-21st century, and 90-100% by late century. Both chilling models consistently projected climatic conditions by the middle to end of the 21st century that will no longer support some of the main tree crops currently grown in California, with the Chilling Hours Model projecting greater changes than the Dynamic Model. The tree crop industry in California will likely need to develop agricultural adaptation measures (e.g. low-chill varieties and dormancy-breaking chemicals) to cope with these projected changes. For some crops, production might no longer be possible.

  7. Can phenological models predict tree phenology accurately under climate change conditions?

    Science.gov (United States)

    Chuine, Isabelle; Bonhomme, Marc; Legave, Jean Michel; García de Cortázar-Atauri, Inaki; Charrier, Guillaume; Lacointe, André; Améglio, Thierry

    2014-05-01

    or compromise dormancy break at the species equatorward range limits leading to a delay or even impossibility to flower or set new leaves. These models are classically parameterized with flowering or budburst dates only, with no information on the dormancy break date because this information is very scarce. We evaluated the efficiency of a set of process-based phenological models to accurately predict the dormancy break dates of four fruit trees. Our results show that models calibrated solely with flowering or budburst dates do not accurately predict the dormancy break date. Providing dormancy break date for the model parameterization results in much more accurate simulation of this latter, with however a higher error than that on flowering or bud break dates. But most importantly, we show also that models not calibrated with dormancy break dates can generate significant differences in forecasted flowering or bud break dates when using climate scenarios. Our results claim for the urgent need of massive measurements of dormancy break dates in forest and fruit trees to yield more robust projections of phenological changes in a near future.

  8. Biodiversity and climate change: consequences for upper tree line in Slovakia

    Directory of Open Access Journals (Sweden)

    Minďaš Jozef

    2016-09-01

    Full Text Available Study of the effects of climate change on upper tree limit has mainly focused on the diversity of tree species as a result of the ability of species to tolerate temperature and moisture changes as well as some effects of disturbance regime changes. The tree species diversity changes due to climate change has been analysed via gap model and biodiversity indices. Gap models are individually based on simulations of establishment, growth, and mortality of each tree on the forest plot. Input ecological data for model calculations have been taken from the permanent research plots located in primeval forests in mountainous regions in Slovakia. The results of regional scenarios of the climatic change for the territory of Slovakia have been used, from which the values according to the CGCM3.1 (global model, KNMI and MPI (regional models. Model results for conditions of the climate change scenarios suggest a shift of the upper forest limit to the region of the present subalpine zone, in supramontane zone. The most significant tree species diversity changes have been identified for the upper tree line and current belt of dwarf pine (Pinus mugo occurrence. Hill’s index of biodiversity in the upper forest line increased by 30 – 35% for horizon of 2050, resp. by 45 – 50% modeled for the horizon of 2075. Calculated values of Shannon’s index show an even higher increase due to climate change. For horizon 2050 is a roughly of three fold increase and horizon for 2075 by almost fivefold increase in the value of the index. Results from the gap model indicate the increase of tree species diversity 2 – 2,5 times.

  9. Using niche-based modelling to assess the impact of climate change on tree functional diversity in Europe

    DEFF Research Database (Denmark)

    Thuiller, Wilfried; Lavorel, Sandra; Sykes, Martin T.

    2006-01-01

    Rapid anthropogenic climate change is already affecting species distributions and ecosystem functioning worldwide. We applied niche-based models to analyse the impact of climate change on tree species and functional diversity in Europe. Present-day climate was used to predict the distributions...... of 122 tree species from different functional types (FT). We then explored projections of future distributions under one climate scenario for 2080, considering two alternative dispersal assumptions: no dispersal and unlimited dispersal. The species-rich broadleaved deciduous group appeared to play a key...... role in the future of different European regions. Temperate areas were projected to lose both species richness and functional diversity due to the loss of broadleaved deciduous trees. These were projected to migrate to boreal forests, thereby increasing their species richness and functional diversity...

  10. Ecohydrological modeling: the consideration of agricultural trees is essential in the Mediterranean area

    Science.gov (United States)

    Fader, Marianela; von Bloh, Werner; Shi, Sinan; Bondeau, Alberte; Cramer, Wolfgang

    2016-04-01

    In the Mediterranean region, climate and land use change are expected to impact on natural and agricultural ecosystems by warming, reduced rainfall and direct degradation of ecosystems. Human population growth and socioeconomic changes, notably on the Eastern and Southern shores, will require increases in food production and put additional pressure on agro-ecosystems and water resources. Coping with these challenges requires informed decisions that, in turn, require assessments by means of a comprehensive ecohydrological model. Here we present here the inclusion of 10 Mediterranean agricultural plants, mainly perennial crops, in an agro-ecosystem model (LPJmL, "Lund-Potsdam-Jena managed Land"): nut trees, date palms, citrus trees, orchards, olive trees, grapes, cotton, potatoes, vegetables and fodder grasses. The model was then successfully tested in three model outputs: agricultural yields, irrigation requirements and soil carbon density. A first application of the model indicates that, currently, agricultural trees consume in average more irrigation water per hectare than annual crops. Also, different crops show different magnitude of changes in net irrigation requirements due to climate change, being the increases most pronounced in agricultural trees. This is very relevant since the Mediterranean area as a whole might face an increase in gross irrigation requirements between 4% and 74% from climate change and population growth if irrigation systems and conveyance are not improved. Additionally, future water scarcity might pose further challenges to the agricultural sector: Algeria, Libya, Israel, Jordan, Lebanon, Syria, Serbia, Morocco, Tunisia and Spain have a high risk of not being able to sustainably meet future irrigation water requirements in some scenarios by the end of the century (1). The importance of including agricultural trees in the ecohydrological models is also shown in the results concerning soil organic carbon (SOC). Since in former model

  11. An Integrated Scenario Ensemble-Based Framework for Hurricane Evacuation Modeling: Part 1-Decision Support System.

    Science.gov (United States)

    Davidson, Rachel A; Nozick, Linda K; Wachtendorf, Tricia; Blanton, Brian; Colle, Brian; Kolar, Randall L; DeYoung, Sarah; Dresback, Kendra M; Yi, Wenqi; Yang, Kun; Leonardo, Nicholas

    2018-03-30

    This article introduces a new integrated scenario-based evacuation (ISE) framework to support hurricane evacuation decision making. It explicitly captures the dynamics, uncertainty, and human-natural system interactions that are fundamental to the challenge of hurricane evacuation, but have not been fully captured in previous formal evacuation models. The hazard is represented with an ensemble of probabilistic scenarios, population behavior with a dynamic decision model, and traffic with a dynamic user equilibrium model. The components are integrated in a multistage stochastic programming model that minimizes risk and travel times to provide a tree of evacuation order recommendations and an evaluation of the risk and travel time performance for that solution. The ISE framework recommendations offer an advance in the state of the art because they: (1) are based on an integrated hazard assessment (designed to ultimately include inland flooding), (2) explicitly balance the sometimes competing objectives of minimizing risk and minimizing travel time, (3) offer a well-hedged solution that is robust under the range of ways the hurricane might evolve, and (4) leverage the substantial value of increasing information (or decreasing degree of uncertainty) over the course of a hurricane event. A case study for Hurricane Isabel (2003) in eastern North Carolina is presented to demonstrate how the framework is applied, the type of results it can provide, and how it compares to available methods of a single scenario deterministic analysis and a two-stage stochastic program. © 2018 Society for Risk Analysis.

  12. Using Service Scenarios to Model Business Services

    DEFF Research Database (Denmark)

    Bækgaard, Lars

    The purpose of the paper is to present and evaluate the notion of service scenarios. A service is work done by a service executor in interaction with a service consumer. A service scenario is a model of a service system and the roles that are played by the actors participating and interacting...... during the execution of a service. The model represents the roles and the interactions between the participants. Service scenarios can be used to model specific services and roles played by human beings and IT systems in the execution of services. The use of service scenarios is demonstrated by means...... of a case study in a public library. The case study indicates that service systems should be understood as socio-technical systems in which service executors and service consumers co-create value in mutual interaction with each other and with a set of shared resources....

  13. Interactive wood combustion for botanical tree models

    KAUST Repository

    Pirk, Sö ren; Jarząbek, Michał; Hadrich, Torsten; Michels, Dominik L.; Palubicki, Wojciech

    2017-01-01

    We present a novel method for the combustion of botanical tree models. Tree models are represented as connected particles for the branching structure and a polygonal surface mesh for the combustion. Each particle stores biological and physical

  14. Phylogenetic tree reconstruction accuracy and model fit when proportions of variable sites change across the tree.

    Science.gov (United States)

    Shavit Grievink, Liat; Penny, David; Hendy, Michael D; Holland, Barbara R

    2010-05-01

    Commonly used phylogenetic models assume a homogeneous process through time in all parts of the tree. However, it is known that these models can be too simplistic as they do not account for nonhomogeneous lineage-specific properties. In particular, it is now widely recognized that as constraints on sequences evolve, the proportion and positions of variable sites can vary between lineages causing heterotachy. The extent to which this model misspecification affects tree reconstruction is still unknown. Here, we evaluate the effect of changes in the proportions and positions of variable sites on model fit and tree estimation. We consider 5 current models of nucleotide sequence evolution in a Bayesian Markov chain Monte Carlo framework as well as maximum parsimony (MP). We show that for a tree with 4 lineages where 2 nonsister taxa undergo a change in the proportion of variable sites tree reconstruction under the best-fitting model, which is chosen using a relative test, often results in the wrong tree. In this case, we found that an absolute test of model fit is a better predictor of tree estimation accuracy. We also found further evidence that MP is not immune to heterotachy. In addition, we show that increased sampling of taxa that have undergone a change in proportion and positions of variable sites is critical for accurate tree reconstruction.

  15. Scenarios in society, society in scenarios: toward a social scientific analysis of storyline-driven environmental modeling

    International Nuclear Information System (INIS)

    Garb, Yaakov; Pulver, Simone; VanDeveer, Stacy D

    2008-01-01

    Scenario analysis, an approach to thinking about alternative futures based on storyline-driven modeling, has become increasingly common and important in attempts to understand and respond to the impacts of human activities on natural systems at a variety of scales. The construction of scenarios is a fundamentally social activity, yet social scientific perspectives have rarely been brought to bear on it. Indeed, there is a growing imbalance between the increasing technical sophistication of the modeling elements of scenarios and the continued simplicity of our understanding of the social origins, linkages, and implications of the narratives to which they are coupled. Drawing on conceptual and methodological tools from science and technology studies, sociology and political science, we offer an overview of what a social scientific analysis of scenarios might include. In particular, we explore both how scenarios intervene in social microscale and macroscale contexts and how aspects of such contexts are embedded in scenarios, often implicitly. Analyzing the social 'work' of scenarios (i) can enhance the understanding of scenario developers and modeling practitioners of the knowledge production processes in which they participate and (ii) can improve the utility of scenario products as decision-support tools to actual, rather than imagined, decision-makers.

  16. A Method of Fire Scenarios Identification in a Consolidated Fire Risk Analysis

    International Nuclear Information System (INIS)

    Lim, Ho Gon; Han, Sang Hoon; Yang, Joon Eon

    2010-01-01

    Conventional fire PSA consider only two cases of fire scenarios, that is one for fire without propagation and the other for single propagation to neighboring compartment. Recently, a consolidated fire risk analysis using single fault tree (FT) was developed. However, the fire scenario identification in the new method is similar to conventional fire analysis method. The present study develops a new method of fire scenario identification in a consolidated fire risk analysis method. An equation for fire propagation is developed to identify fire scenario and a mapping method of fire scenarios into internal event risk model is discussed. Finally, an algorithm for automatic program is suggested

  17. Estimation of Tree Lists from Airborne Laser Scanning Using Tree Model Clustering and k-MSN Imputation

    Directory of Open Access Journals (Sweden)

    Jörgen Wallerman

    2013-04-01

    Full Text Available Individual tree crowns may be delineated from airborne laser scanning (ALS data by segmentation of surface models or by 3D analysis. Segmentation of surface models benefits from using a priori knowledge about the proportions of tree crowns, which has not yet been utilized for 3D analysis to any great extent. In this study, an existing surface segmentation method was used as a basis for a new tree model 3D clustering method applied to ALS returns in 104 circular field plots with 12 m radius in pine-dominated boreal forest (64°14'N, 19°50'E. For each cluster below the tallest canopy layer, a parabolic surface was fitted to model a tree crown. The tree model clustering identified more trees than segmentation of the surface model, especially smaller trees below the tallest canopy layer. Stem attributes were estimated with k-Most Similar Neighbours (k-MSN imputation of the clusters based on field-measured trees. The accuracy at plot level from the k-MSN imputation (stem density root mean square error or RMSE 32.7%; stem volume RMSE 28.3% was similar to the corresponding results from the surface model (stem density RMSE 33.6%; stem volume RMSE 26.1% with leave-one-out cross-validation for one field plot at a time. Three-dimensional analysis of ALS data should also be evaluated in multi-layered forests since it identified a larger number of small trees below the tallest canopy layer.

  18. Modeling Caribbean tree stem diameters from tree height and crown width measurements

    Science.gov (United States)

    Thomas Brandeis; KaDonna Randolph; Mike Strub

    2009-01-01

    Regression models to predict diameter at breast height (DBH) as a function of tree height and maximum crown radius were developed for Caribbean forests based on data collected by the U.S. Forest Service in the Commonwealth of Puerto Rico and Territory of the U.S. Virgin Islands. The model predicting DBH from tree height fit reasonably well (R2 = 0.7110), with...

  19. Application of Goal Tree-Success Tree model as the knowledge-base of operator advisory systems

    International Nuclear Information System (INIS)

    Kim, I.S.; Modarres, M.

    1987-01-01

    The most important portion of an expert system development is the articulation of knowledge by the expert and its satisfactory formulation in a suitable knowledge representation scheme for mechanization by a computer. A 'deep knowledge' approach called Goal Tree-Success Tree model is devised to represent complex dynamic domain knowledge. This approach can hierarchically model the underlying principles of a given process domain (for example nuclear power plant operations domain). The Goal Tree-Success Tree can then be used to represent the knowledge-base and provide means of selecting an efficient search routine in the inference engine of an expert system. A prototype expert system has been developed to demonstrate the method. This expert system models the operation of a typical system used in the pressurized water reactors. The expert system is modeled for real-time operations if an interface between plant parameters and the expert system is established. The real-time operation provides an ability to quickly remedy minor disturbances that can quickly lead to a system malfunction or trip. A description of both the Goal Tree-Success Tree model and the prototype expert system is presented. (orig.)

  20. "Growing trees backwards": Description of a stand reconstruction model

    Science.gov (United States)

    Jonathan D. Bakker; Andrew J. Sanchez Meador; Peter Z. Fule; David W. Huffman; Margaret M. Moore

    2008-01-01

    We describe an individual-tree model that uses contemporary measurements to "grow trees backward" and reconstruct past tree diameters and stand structure in ponderosa pine dominated stands of the Southwest. Model inputs are contemporary structural measurements of all snags, logs, stumps, and living trees, and radial growth measurements, if available. Key...

  1. Tree biomass in the Swiss landscape: nationwide modelling for improved accounting for forest and non-forest trees.

    Science.gov (United States)

    Price, B; Gomez, A; Mathys, L; Gardi, O; Schellenberger, A; Ginzler, C; Thürig, E

    2017-03-01

    Trees outside forest (TOF) can perform a variety of social, economic and ecological functions including carbon sequestration. However, detailed quantification of tree biomass is usually limited to forest areas. Taking advantage of structural information available from stereo aerial imagery and airborne laser scanning (ALS), this research models tree biomass using national forest inventory data and linear least-square regression and applies the model both inside and outside of forest to create a nationwide model for tree biomass (above ground and below ground). Validation of the tree biomass model against TOF data within settlement areas shows relatively low model performance (R 2 of 0.44) but still a considerable improvement on current biomass estimates used for greenhouse gas inventory and carbon accounting. We demonstrate an efficient and easily implementable approach to modelling tree biomass across a large heterogeneous nationwide area. The model offers significant opportunity for improved estimates on land use combination categories (CC) where tree biomass has either not been included or only roughly estimated until now. The ALS biomass model also offers the advantage of providing greater spatial resolution and greater within CC spatial variability compared to the current nationwide estimates.

  2. How much does climate change threaten European forest tree species distributions?

    Science.gov (United States)

    Dyderski, Marcin K; Paź, Sonia; Frelich, Lee E; Jagodziński, Andrzej M

    2018-03-01

    Although numerous species distribution models have been developed, most were based on insufficient distribution data or used older climate change scenarios. We aimed to quantify changes in projected ranges and threat level by the years 2061-2080, for 12 European forest tree species under three climate change scenarios. We combined tree distribution data from the Global Biodiversity Information Facility, EUFORGEN, and forest inventories, and we developed species distribution models using MaxEnt and 19 bioclimatic variables. Models were developed for three climate change scenarios-optimistic (RCP2.6), moderate (RCP4.5), and pessimistic (RPC8.5)-using three General Circulation Models, for the period 2061-2080. Our study revealed different responses of tree species to projected climate change. The species may be divided into three groups: "winners"-mostly late-successional species: Abies alba, Fagus sylvatica, Fraxinus excelsior, Quercus robur, and Quercus petraea; "losers"-mostly pioneer species: Betula pendula, Larix decidua, Picea abies, and Pinus sylvestris; and alien species-Pseudotsuga menziesii, Quercus rubra, and Robinia pseudoacacia, which may be also considered as "winners." Assuming limited migration, most of the species studied would face a significant decrease in suitable habitat area. The threat level was highest for species that currently have the northernmost distribution centers. Ecological consequences of the projected range contractions would be serious for both forest management and nature conservation. © 2017 John Wiley & Sons Ltd.

  3. Modeling and Understanding Time-Evolving Scenarios

    Directory of Open Access Journals (Sweden)

    Riccardo Melen

    2015-08-01

    Full Text Available In this paper, we consider the problem of modeling application scenarios characterized by variability over time and involving heterogeneous kinds of knowledge. The evolution of distributed technologies creates new and challenging possibilities of integrating different kinds of problem solving methods, obtaining many benefits from the user point of view. In particular, we propose here a multilayer modeling system and adopt the Knowledge Artifact concept to tie together statistical and Artificial Intelligence rule-based methods to tackle problems in ubiquitous and distributed scenarios.

  4. Development and application of a tree-code in simulation scenarios of the plasma-wall interaction

    International Nuclear Information System (INIS)

    Berberich, Benjamin

    2012-03-01

    Processes in the plasma edge layer of magnetic fusion devices occur on widely disparate length- and time-scales. Also recently developed features in this particular region, such as stochastic magnetic fields, underline the necessity for three dimensional, full-kinetic simulation tools. Contemporary programs often deploy ad hoc assumptions and approximations for microscopic phenomena for which self-consistent ab initio models in principle exist, but are still computationally too expensive or complex to implement. Recently, mesh-free methods have matured into a new class of tools for such first-principles computations which thanks to their geometric flexibility are highly promising for tackling complicated TOKAMAK regions. In this work we have develop the massively parallel Tree-Code PEPC-B (Pretty Efficient Parallel Coulomb solver) into a new tool for plasma material interaction studies. After a brief overview of the working principles of Tree-Codes two main topic groups are addressed: First the leap-frog Boris integration scheme is discussed and its numerical limitations are pointed out. To overcome these limitations the method is enhanced to a guiding-center integrator. As a proof of principal, numerical experiments are conducted reproducing the anticipated drift kinetic aspects of particle orbits. It turns out that this new technique is much less sensitive to large time steps than the original concept was. One major drawback of mesh-free methods which hinders their direct use for plasma-edge simulations is the difficulty in representing solid structures and associated boundary conditions. Therefore, an alternative concept is proposed using charge carrying Wall-Particles, which fits naturally in the mesh-free doctrine. These developments incorporate the second main topic group of this report. To prove the physical correctness of this new idea, a quasi one dimensional plasma-wall interface scenario is chosen. By studying the system with great detail, good agreement

  5. Maximum parsimony, substitution model, and probability phylogenetic trees.

    Science.gov (United States)

    Weng, J F; Thomas, D A; Mareels, I

    2011-01-01

    The problem of inferring phylogenies (phylogenetic trees) is one of the main problems in computational biology. There are three main methods for inferring phylogenies-Maximum Parsimony (MP), Distance Matrix (DM) and Maximum Likelihood (ML), of which the MP method is the most well-studied and popular method. In the MP method the optimization criterion is the number of substitutions of the nucleotides computed by the differences in the investigated nucleotide sequences. However, the MP method is often criticized as it only counts the substitutions observable at the current time and all the unobservable substitutions that really occur in the evolutionary history are omitted. In order to take into account the unobservable substitutions, some substitution models have been established and they are now widely used in the DM and ML methods but these substitution models cannot be used within the classical MP method. Recently the authors proposed a probability representation model for phylogenetic trees and the reconstructed trees in this model are called probability phylogenetic trees. One of the advantages of the probability representation model is that it can include a substitution model to infer phylogenetic trees based on the MP principle. In this paper we explain how to use a substitution model in the reconstruction of probability phylogenetic trees and show the advantage of this approach with examples.

  6. Estimation of Tree Cover in an Agricultural Parkland of Senegal Using Rule-Based Regression Tree Modeling

    Directory of Open Access Journals (Sweden)

    Stefanie M. Herrmann

    2013-10-01

    Full Text Available Field trees are an integral part of the farmed parkland landscape in West Africa and provide multiple benefits to the local environment and livelihoods. While field trees have received increasing interest in the context of strengthening resilience to climate variability and change, the actual extent of farmed parkland and spatial patterns of tree cover are largely unknown. We used the rule-based predictive modeling tool Cubist® to estimate field tree cover in the west-central agricultural region of Senegal. A collection of rules and associated multiple linear regression models was constructed from (1 a reference dataset of percent tree cover derived from very high spatial resolution data (2 m Orbview as the dependent variable, and (2 ten years of 10-day 250 m Moderate Resolution Imaging Spectrometer (MODIS Normalized Difference Vegetation Index (NDVI composites and derived phenological metrics as independent variables. Correlation coefficients between modeled and reference percent tree cover of 0.88 and 0.77 were achieved for training and validation data respectively, with absolute mean errors of 1.07 and 1.03 percent tree cover. The resulting map shows a west-east gradient from high tree cover in the peri-urban areas of horticulture and arboriculture to low tree cover in the more sparsely populated eastern part of the study area. A comparison of current (2000s tree cover along this gradient with historic cover as seen on Corona images reveals dynamics of change but also areas of remarkable stability of field tree cover since 1968. The proposed modeling approach can help to identify locations of high and low tree cover in dryland environments and guide ground studies and management interventions aimed at promoting the integration of field trees in agricultural systems.

  7. FB-Tree: A B+-Tree for Flash-Based SSDs

    DEFF Research Database (Denmark)

    Jørgensen, Martin V.; Rasmussen, René B.; Saltenis, Simonas

    2011-01-01

    Due to their many advantages, flash-based SSDs (Solid-State Drives) have become a mainstream alternative to magnetic disks for database servers. Nevertheless, database systems, designed and optimized for magnetic disks, still do not fully exploit all the benefits of the new technology. We propose....... As a consequence, the FB-tree outperforms a regular B+-tree in all scenarios tested. For instance, the throughput of a random workload of 75% updates increases by a factor of three using only two times the space of the B+-tree....

  8. Assessing forest vulnerability to climate warming using a process-based model of tree growth: bad prospects for rear-edges.

    Science.gov (United States)

    Sánchez-Salguero, Raúl; Camarero, Jesus Julio; Gutiérrez, Emilia; González Rouco, Fidel; Gazol, Antonio; Sangüesa-Barreda, Gabriel; Andreu-Hayles, Laia; Linares, Juan Carlos; Seftigen, Kristina

    2017-07-01

    Growth models can be used to assess forest vulnerability to climate warming. If global warming amplifies water deficit in drought-prone areas, tree populations located at the driest and southernmost distribution limits (rear-edges) should be particularly threatened. Here, we address these statements by analyzing and projecting growth responses to climate of three major tree species (silver fir, Abies alba; Scots pine, Pinus sylvestris; and mountain pine, Pinus uncinata) in mountainous areas of NE Spain. This region is subjected to Mediterranean continental conditions, it encompasses wide climatic, topographic and environmental gradients, and, more importantly, it includes rear-edges of the continuous distributions of these tree species. We used tree-ring width data from a network of 110 forests in combination with the process-based Vaganov-Shashkin-Lite growth model and climate-growth analyses to forecast changes in tree growth during the 21st century. Climatic projections were based on four ensembles CO 2 emission scenarios. Warm and dry conditions during the growing season constrain silver fir and Scots pine growth, particularly at the species rear-edge. By contrast, growth of high-elevation mountain pine forests is enhanced by climate warming. The emission scenario (RCP 8.5) corresponding to the most pronounced warming (+1.4 to 4.8 °C) forecasted mean growth reductions of -10.7% and -16.4% in silver fir and Scots pine, respectively, after 2050. This indicates that rising temperatures could amplify drought stress and thus constrain the growth of silver fir and Scots pine rear-edge populations growing at xeric sites. Contrastingly, mountain pine growth is expected to increase by +12.5% due to a longer and warmer growing season. The projections of growth reduction in silver fir and Scots pine portend dieback and a contraction of their species distribution areas through potential local extinctions of the most vulnerable driest rear-edge stands. Our modeling

  9. Using a Numerical Model to Assess the Geomorphic Impacts of Forest Management Scenarios on Streams

    Science.gov (United States)

    Davidson, S. L.; Eaton, B. C.

    2014-12-01

    In-stream large wood governs the morphology of many small to intermediate streams, while riparian vegetation influences bank strength and channel pattern. Forest management practices such as harvesting and fire suppression therefore dramatically influence channel processes and associated aquatic habitat. The primary objective of this research is to compare the impacts of three common forest scenarios - natural fire disturbance, forest harvesting with a riparian buffer, and fire suppression - on the volume of in-channel wood and the complexity of aquatic habitat in channels at a range of scales. Each scenario is explored through Monte Carlo simulations run over a period of 1000 years using a numerical reach scale channel simulator (RSCS), with variations in tree toppling rate and forest density used to represent each forest management trajectory. The habitat complexity associated with each scenario is assessed based on the area of the bed occupied by pools and spawning sized sediment, the availability of wood cover, and the probability of avulsion. Within the fire scenario, we also use the model to separately investigate the effects of root decay and recovery on equilibrium channel geometry by varying the rooting depth and associated bank strength through time. The results show that wood loading and habitat complexity are influenced by the timing and magnitude of wood recruitment, as well as channel scale. The forest harvesting scenario produces the lowest wood loads and habitat complexity so long as the buffer width is less than the average mature tree height. The natural fire cycle produces the greatest wood loading and habitat complexity, but also the greatest variability because these streams experience significant periods without wood recruitment as forests regenerate. In reaches that experience recurrent fires, width increases in the post-fire period as roots decay, at times producing a change in channel pattern when a threshold width to depth ratio is

  10. Fast admixture analysis and population tree estimation for SNP and NGS data

    DEFF Research Database (Denmark)

    Cheng, Jade Yu; Mailund, Thomas; Nielsen, Rasmus

    2017-01-01

    assumption for identifying ancestry components correctly and for inferring the correct tree. In most cases, ancestry components are inferred correctly, although sample sizes and times since admixture can influence the results. We show that the popular Gaussian approximation tends to perform poorly under......-calling associated with Next Generation Sequencing (NGS) data. We also present a new method for estimating population trees from ancestry components using a Gaussian approximation. Using coalescence simulations of diverging populations, we explore the adequacy of the STRUCTURE-style models and the Gaussian...... extreme divergence scenarios e.g. with very long branch lengths, but the topologies of the population trees are accurately inferred in all scenarios explored. The new methods are implemented together with appropriate visualization tools in the software package Ohana....

  11. PERFORMANCE COMPARISON OF SCENARIO-GENERATION METHODS APPLIED TO A STOCHASTIC OPTIMIZATION ASSET-LIABILITY MANAGEMENT MODEL

    Directory of Open Access Journals (Sweden)

    Alan Delgado de Oliveira

    Full Text Available ABSTRACT In this paper, we provide an empirical discussion of the differences among some scenario tree-generation approaches for stochastic programming. We consider the classical Monte Carlo sampling and Moment matching methods. Moreover, we test the Resampled average approximation, which is an adaptation of Monte Carlo sampling and Monte Carlo with naive allocation strategy as the benchmark. We test the empirical effects of each approach on the stability of the problem objective function and initial portfolio allocation, using a multistage stochastic chance-constrained asset-liability management (ALM model as the application. The Moment matching and Resampled average approximation are more stable than the other two strategies.

  12. New substitution models for rooting phylogenetic trees.

    Science.gov (United States)

    Williams, Tom A; Heaps, Sarah E; Cherlin, Svetlana; Nye, Tom M W; Boys, Richard J; Embley, T Martin

    2015-09-26

    The root of a phylogenetic tree is fundamental to its biological interpretation, but standard substitution models do not provide any information on its position. Here, we describe two recently developed models that relax the usual assumptions of stationarity and reversibility, thereby facilitating root inference without the need for an outgroup. We compare the performance of these models on a classic test case for phylogenetic methods, before considering two highly topical questions in evolutionary biology: the deep structure of the tree of life and the root of the archaeal radiation. We show that all three alignments contain meaningful rooting information that can be harnessed by these new models, thus complementing and extending previous work based on outgroup rooting. In particular, our analyses exclude the root of the tree of life from the eukaryotes or Archaea, placing it on the bacterial stem or within the Bacteria. They also exclude the root of the archaeal radiation from several major clades, consistent with analyses using other rooting methods. Overall, our results demonstrate the utility of non-reversible and non-stationary models for rooting phylogenetic trees, and identify areas where further progress can be made. © 2015 The Authors.

  13. From scenarios to domain models: processes and representations

    Science.gov (United States)

    Haddock, Gail; Harbison, Karan

    1994-03-01

    The domain specific software architectures (DSSA) community has defined a philosophy for the development of complex systems. This philosophy improves productivity and efficiency by increasing the user's role in the definition of requirements, increasing the systems engineer's role in the reuse of components, and decreasing the software engineer's role to the development of new components and component modifications only. The scenario-based engineering process (SEP), the first instantiation of the DSSA philosophy, has been adopted by the next generation controller project. It is also the chosen methodology of the trauma care information management system project, and the surrogate semi-autonomous vehicle project. SEP uses scenarios from the user to create domain models and define the system's requirements. Domain knowledge is obtained from a variety of sources including experts, documents, and videos. This knowledge is analyzed using three techniques: scenario analysis, task analysis, and object-oriented analysis. Scenario analysis results in formal representations of selected scenarios. Task analysis of the scenario representations results in descriptions of tasks necessary for object-oriented analysis and also subtasks necessary for functional system analysis. Object-oriented analysis of task descriptions produces domain models and system requirements. This paper examines the representations that support the DSSA philosophy, including reference requirements, reference architectures, and domain models. The processes used to create and use the representations are explained through use of the scenario-based engineering process. Selected examples are taken from the next generation controller project.

  14. Modelling diameter growth, mortality and recruitment of trees in ...

    African Journals Online (AJOL)

    Modelling diameter growth, mortality and recruitment of trees in miombo woodlands of Tanzania. ... Individual tree diameter growth and mortality models, and area-based recruitment models were developed. ... AJOL African Journals Online.

  15. Modelling agro-forestry scenarios for ammonia abatement in the landscape

    International Nuclear Information System (INIS)

    Bealey, W J; Braban, C F; Famulari, D; Theobald, M R; Reis, S; Sutton, M A; Loubet, B; Reay, D S

    2014-01-01

    Ammonia emissions from livestock production can have negative impacts on nearby protected sites and ecosystems that are sensitive to eutrophication and acidification. Trees are effective scavengers of both gaseous and particulate pollutants from the atmosphere making tree belts potentially effective landscape features to support strategies aiming to reduce ammonia impacts. This research used the MODDAS-THETIS a coupled turbulence and deposition turbulence model, to examine the relationships between tree canopy structure and ammonia capture for three source types—animal housing, slurry lagoon, and livestock under a tree canopy. By altering the canopy length, leaf area index, leaf area density, and height of the canopy in the model the capture efficiencies varied substantially. A maximum of 27% of the emitted ammonia was captured by tree canopy for the animal housing source, for the slurry lagoon the maximum was 19%, while the livestock under trees attained a maximum of 60% recapture. Using agro-forestry systems of differing tree structures near ‘hot spots’ of ammonia in the landscape could provide an effective abatement option for the livestock industry that complements existing source reduction measures. (paper)

  16. Pesticide bioconcentration modelling for fruit trees.

    Science.gov (United States)

    Paraíba, Lourival Costa

    2007-01-01

    The model presented allows simulating the pesticide concentration evolution in fruit trees and estimating the pesticide bioconcentration factor in fruits. Pesticides are non-ionic organic compounds that are degraded in soils cropped with woody species, fruit trees and other perennials. The model allows estimating the pesticide uptake by plants through the water transpiration stream and also the time in which maximum pesticide concentration occur in the fruits. The equation proposed presents the relationships between bioconcentration factor (BCF) and the following variables: plant water transpiration volume (Q), pesticide transpiration stream concentration factor (TSCF), pesticide stem-water partition coefficient (K(Wood,W)), stem dry biomass (M) and pesticide dissipation rate in the soil-plant system (k(EGS)). The modeling started and was developed from a previous model "Fruit Tree Model" (FTM), reported by Trapp and collaborators in 2003, to which was added the hypothesis that the pesticide degradation in the soil follows a first order kinetic equation. The FTM model for pesticides (FTM-p) was applied to a hypothetic mango plant cropping (Mangifera indica) treated with paclobutrazol (growth regulator) added to the soil. The model fitness was evaluated through the sensitivity analysis of the pesticide BCF values in fruits with respect to the model entry data variability.

  17. Modeling and Testing Landslide Hazard Using Decision Tree

    Directory of Open Access Journals (Sweden)

    Mutasem Sh. Alkhasawneh

    2014-01-01

    Full Text Available This paper proposes a decision tree model for specifying the importance of 21 factors causing the landslides in a wide area of Penang Island, Malaysia. These factors are vegetation cover, distance from the fault line, slope angle, cross curvature, slope aspect, distance from road, geology, diagonal length, longitude curvature, rugosity, plan curvature, elevation, rain perception, soil texture, surface area, distance from drainage, roughness, land cover, general curvature, tangent curvature, and profile curvature. Decision tree models are used for prediction, classification, and factors importance and are usually represented by an easy to interpret tree like structure. Four models were created using Chi-square Automatic Interaction Detector (CHAID, Exhaustive CHAID, Classification and Regression Tree (CRT, and Quick-Unbiased-Efficient Statistical Tree (QUEST. Twenty-one factors were extracted using digital elevation models (DEMs and then used as input variables for the models. A data set of 137570 samples was selected for each variable in the analysis, where 68786 samples represent landslides and 68786 samples represent no landslides. 10-fold cross-validation was employed for testing the models. The highest accuracy was achieved using Exhaustive CHAID (82.0% compared to CHAID (81.9%, CRT (75.6%, and QUEST (74.0% model. Across the four models, five factors were identified as most important factors which are slope angle, distance from drainage, surface area, slope aspect, and cross curvature.

  18. Simulating phenological shifts in French temperate forests under two climatic change scenarios and four driving global circulation models

    Science.gov (United States)

    Lebourgeois, François; Pierrat, Jean-Claude; Perez, Vincent; Piedallu, Christian; Cecchini, Sébastien; Ulrich, Erwin

    2010-09-01

    After modeling the large-scale climate response patterns of leaf unfolding, leaf coloring and growing season length of evergreen and deciduous French temperate trees, we predicted the effects of eight future climate scenarios on phenological events. We used the ground observations from 103 temperate forests (10 species and 3,708 trees) from the French Renecofor Network and for the period 1997-2006. We applied RandomForest algorithms to predict phenological events from climatic and ecological variables. With the resulting models, we drew maps of phenological events throughout France under present climate and under two climatic change scenarios (A2, B2) and four global circulation models (HadCM3, CGCM2, CSIRO2 and PCM). We compared current observations and predicted values for the periods 2041-2070 and 2071-2100. On average, spring development of oaks precedes that of beech, which precedes that of conifers. Annual cycles in budburst and leaf coloring are highly correlated with January, March-April and October-November weather conditions through temperature, global solar radiation or potential evapotranspiration depending on species. At the end of the twenty-first century, each model predicts earlier budburst (mean: 7 days) and later leaf coloring (mean: 13 days) leading to an average increase in the growing season of about 20 days (for oaks and beech stands). The A2-HadCM3 hypothesis leads to an increase of up to 30 days in many areas. As a consequence of higher predicted warming during autumn than during winter or spring, shifts in leaf coloring dates appear greater than trends in leaf unfolding. At a regional scale, highly differing climatic response patterns were observed.

  19. Low Tree-Growth Elasticity of Forest Biomass Indicated by an Individual-Based Model

    Directory of Open Access Journals (Sweden)

    Robbie A. Hember

    2018-01-01

    Full Text Available Environmental conditions and silviculture fundamentally alter the metabolism of individual trees and, therefore, need to be studied at that scale. However, changes in forest biomass density (Mg C ha−1 may be decoupled from changes in growth (kg C year−1 when the latter also accelerates the life cycle of trees and strains access to light, nutrients, and water. In this study, we refer to an individual-based model of forest biomass dynamics to constrain the magnitude of system feedbacks associated with ontogeny and competition and estimate the scaling relationship between changes in tree growth and forest biomass density. The model was driven by fitted equations of annual aboveground biomass growth (Gag, probability of recruitment (Pr, and probability of mortality (Pm parameterized against field observations of black spruce (Picea mariana (Mill. BSP, interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn. Franco, and western hemlock (Tsuga heterophylla (Raf. Sarg.. A hypothetical positive step-change in mean tree growth was imposed half way through the simulations and landscape-scale responses were then evaluated by comparing pre- and post-stimulus periods. Imposing a 100% increase in tree growth above calibrated predictions (i.e., contemporary rates only translated into 36% to 41% increases in forest biomass density. This corresponded with a tree-growth elasticity of forest biomass (εG,SB ranging from 0.33 to 0.55. The inelastic nature of stand biomass density was attributed to the dependence of mortality on intensity of competition and tree size, which decreased stand density by 353 to 495 trees ha−1, and decreased biomass residence time by 10 to 23 years. Values of εG,SB depended on the magnitude of the stimulus. For example, a retrospective scenario in which tree growth increased from 50% below contemporary rates up to contemporary rates indicated values of εG,SB ranging from 0.66 to 0.75. We conclude that: (1 effects of

  20. Climate change affects winter chill for temperate fruit and nut trees.

    Science.gov (United States)

    Luedeling, Eike; Girvetz, Evan H; Semenov, Mikhail A; Brown, Patrick H

    2011-01-01

    Temperate fruit and nut trees require adequate winter chill to produce economically viable yields. Global warming has the potential to reduce available winter chill and greatly impact crop yields. We estimated winter chill for two past (1975 and 2000) and 18 future scenarios (mid and end 21st century; 3 Global Climate Models [GCMs]; 3 greenhouse gas emissions [GHG] scenarios). For 4,293 weather stations around the world and GCM projections, Safe Winter Chill (SWC), the amount of winter chill that is exceeded in 90% of all years, was estimated for all scenarios using the "Dynamic Model" and interpolated globally. We found that SWC ranged between 0 and about 170 Chill Portions (CP) for all climate scenarios, but that the global distribution varied across scenarios. Warm regions are likely to experience severe reductions in available winter chill, potentially threatening production there. In contrast, SWC in most temperate growing regions is likely to remain relatively unchanged, and cold regions may even see an increase in SWC. Climate change impacts on SWC differed quantitatively among GCMs and GHG scenarios, with the highest GHG leading to losses up to 40 CP in warm regions, compared to 20 CP for the lowest GHG. The extent of projected changes in winter chill in many major growing regions of fruits and nuts indicates that growers of these commodities will likely experience problems in the future. Mitigation of climate change through reductions in greenhouse gas emissions can help reduce the impacts, however, adaption to changes will have to occur. To better prepare for likely impacts of climate change, efforts should be undertaken to breed tree cultivars for lower chilling requirements, to develop tools to cope with insufficient winter chill, and to better understand the temperature responses of tree crops.

  1. Realistic modelling of external flooding scenarios - A multi-disciplinary approach

    International Nuclear Information System (INIS)

    Brinkman, J.L.

    2014-01-01

    against flooding and timing of the events into account as basis for the development and screening of flooding scenarios. Realistic modelling of external flooding scenarios in a PSA requires a multi-disciplinary approach. Next to being thoroughly familiar with the design features of the plant against flooding, like its critical elevations for safety (related) equipment and the strength of buildings, additional knowledge is necessary on design of flood protection measures as dikes and dunes, their failure behaviour and modelling. The approach does not change the basic flooding scenarios - the event tree structure - itself, but impacts the initiating event of the specific flooding scenarios. (authors)

  2. Model Performance Evaluation and Scenario Analysis (MPESA)

    Science.gov (United States)

    Model Performance Evaluation and Scenario Analysis (MPESA) assesses the performance with which models predict time series data. The tool was developed Hydrological Simulation Program-Fortran (HSPF) and the Stormwater Management Model (SWMM)

  3. Selective Tree-ring Models: A Novel Method for Reconstructing Streamflow Using Tree Rings

    Science.gov (United States)

    Foard, M. B.; Nelson, A. S.; Harley, G. L.

    2017-12-01

    Surface water is among the most instrumental and vulnerable resources in the Northwest United States (NW). Recent observations show that overall water quantity is declining in streams across the region, while extreme flooding events occur more frequently. Historical streamflow models inform probabilities of extreme flow events (flood or drought) by describing frequency and duration of past events. There are numerous examples of tree-rings being utilized to reconstruct streamflow in the NW. These models confirm that tree-rings are highly accurate at predicting streamflow, however there are many nuances that limit their applicability through time and space. For example, most models predict streamflow from hydrologically altered rivers (e.g. dammed, channelized) which may hinder our ability to predict natural prehistoric flow. They also have a tendency to over/under-predict extreme flow events. Moreover, they often neglect to capture the changing relationships between tree-growth and streamflow over time and space. To address these limitations, we utilized national tree-ring and streamflow archives to investigate the relationships between the growth of multiple coniferous species and free-flowing streams across the NW using novel species-and site-specific streamflow models - a term we coined"selective tree-ring models." Correlation function analysis and regression modeling were used to evaluate the strengths and directions of the flow-growth relationships. Species with significant relationships in the same direction were identified as strong candidates for selective models. Temporal and spatial patterns of these relationships were examined using running correlations and inverse distance weighting interpolation, respectively. Our early results indicate that (1) species adapted to extreme climates (e.g. hot-dry, cold-wet) exhibit the most consistent relationships across space, (2) these relationships weaken in locations with mild climatic variability, and (3) some

  4. Metapopulation modelling of riparian tree species persistence in river networks under climate change.

    Science.gov (United States)

    Van Looy, Kris; Piffady, Jérémy

    2017-11-01

    Floodplain landscapes are highly fragmented by river regulation resulting in habitat degradation and flood regime perturbation, posing risks to population persistence. Climate change is expected to pose supplementary risks in this context of fragmented landscapes, and especially for river systems adaptation management programs are developed. The association of habitat quality and quantity with the landscape dynamics and resilience to human-induced disturbances is still poorly understood in the context of species survival and colonization processes, but essential to prioritize conservation and restoration actions. We present a modelling approach that elucidates network connectivity and landscape dynamics in spatial and temporal context to identify vital corridors and conservation priorities in the Loire river and its tributaries. Alteration of flooding and flow regimes is believed to be critical to population dynamics in river ecosystems. Still, little is known of critical levels of alteration both spatially and temporally. We applied metapopulation modelling approaches for a dispersal-limited tree species, white elm; and a recruitment-limited tree species, black poplar. In different model steps the connectivity and natural dynamics of the river landscape are confronted with physical alterations (dams/dykes) to species survival and then future scenarios for climatic changes and potential adaptation measures are entered in the model and translated in population persistence over the river basin. For the two tree species we highlighted crucial network zones in relation to habitat quality and connectivity. Where the human impact model already shows currently restricted metapopulation development, climate change is projected to aggravate this persistence perspective substantially. For both species a significant drawback to the basin population is observed, with 1/3 for elm and ¼ for poplar after 25 years already. But proposed adaptation measures prove effective to even

  5. Tree mortality predicted from drought-induced vascular damage

    Science.gov (United States)

    Anderegg, William R.L.; Flint, Alan L.; Huang, Cho-ying; Flint, Lorraine E.; Berry, Joseph A.; Davis, Frank W.; Sperry, John S.; Field, Christopher B.

    2015-01-01

    The projected responses of forest ecosystems to warming and drying associated with twenty-first-century climate change vary widely from resiliency to widespread tree mortality1, 2, 3. Current vegetation models lack the ability to account for mortality of overstorey trees during extreme drought owing to uncertainties in mechanisms and thresholds causing mortality4, 5. Here we assess the causes of tree mortality, using field measurements of branch hydraulic conductivity during ongoing mortality in Populus tremuloides in the southwestern United States and a detailed plant hydraulics model. We identify a lethal plant water stress threshold that corresponds with a loss of vascular transport capacity from air entry into the xylem. We then use this hydraulic-based threshold to simulate forest dieback during historical drought, and compare predictions against three independent mortality data sets. The hydraulic threshold predicted with 75% accuracy regional patterns of tree mortality as found in field plots and mortality maps derived from Landsat imagery. In a high-emissions scenario, climate models project that drought stress will exceed the observed mortality threshold in the southwestern United States by the 2050s. Our approach provides a powerful and tractable way of incorporating tree mortality into vegetation models to resolve uncertainty over the fate of forest ecosystems in a changing climate.

  6. Extended tree-level gauge mediation

    DEFF Research Database (Denmark)

    Monaco, M.; Nardecchia, M.; Romanino, A.

    2011-01-01

    Tree-level gauge mediation (TGM) is a scenario of SUSY breaking in which the tree-level exchange of heavy (possibly GUT) vector fields generates flavor-universal sfermion masses. In this work we extend this framework to the case of E(6) that is the natural extension of the minimal case studied so...... if the gauge group does not contain SU(5). If SUSY breaking is mediated purely by the U(1) generator that commutes with SO(10) we obtain universal sfermion masses and thus can derive the CMSSM boundary conditions in a novel scenario....

  7. Two graphical user interfaces for managing and analyzing MODFLOW groundwater-model scenarios

    Science.gov (United States)

    Banta, Edward R.

    2014-01-01

    Scenario Manager and Scenario Analyzer are graphical user interfaces that facilitate the use of calibrated, MODFLOW-based groundwater models for investigating possible responses to proposed stresses on a groundwater system. Scenario Manager allows a user, starting with a calibrated model, to design and run model scenarios by adding or modifying stresses simulated by the model. Scenario Analyzer facilitates the process of extracting data from model output and preparing such display elements as maps, charts, and tables. Both programs are designed for users who are familiar with the science on which groundwater modeling is based but who may not have a groundwater modeler’s expertise in building and calibrating a groundwater model from start to finish. With Scenario Manager, the user can manipulate model input to simulate withdrawal or injection wells, time-variant specified hydraulic heads, recharge, and such surface-water features as rivers and canals. Input for stresses to be simulated comes from user-provided geographic information system files and time-series data files. A Scenario Manager project can contain multiple scenarios and is self-documenting. Scenario Analyzer can be used to analyze output from any MODFLOW-based model; it is not limited to use with scenarios generated by Scenario Manager. Model-simulated values of hydraulic head, drawdown, solute concentration, and cell-by-cell flow rates can be presented in display elements. Map data can be represented as lines of equal value (contours) or as a gradated color fill. Charts and tables display time-series data obtained from output generated by a transient-state model run or from user-provided text files of time-series data. A display element can be based entirely on output of a single model run, or, to facilitate comparison of results of multiple scenarios, an element can be based on output from multiple model runs. Scenario Analyzer can export display elements and supporting metadata as a Portable

  8. Algorithmic fault tree construction by component-based system modeling

    International Nuclear Information System (INIS)

    Majdara, Aref; Wakabayashi, Toshio

    2008-01-01

    Computer-aided fault tree generation can be easier, faster and less vulnerable to errors than the conventional manual fault tree construction. In this paper, a new approach for algorithmic fault tree generation is presented. The method mainly consists of a component-based system modeling procedure an a trace-back algorithm for fault tree synthesis. Components, as the building blocks of systems, are modeled using function tables and state transition tables. The proposed method can be used for a wide range of systems with various kinds of components, if an inclusive component database is developed. (author)

  9. A tree-parenchyma coupled model for lung ventilation simulation.

    Science.gov (United States)

    Pozin, Nicolas; Montesantos, Spyridon; Katz, Ira; Pichelin, Marine; Vignon-Clementel, Irene; Grandmont, Céline

    2017-11-01

    In this article, we develop a lung ventilation model. The parenchyma is described as an elastic homogenized media. It is irrigated by a space-filling dyadic resistive pipe network, which represents the tracheobronchial tree. In this model, the tree and the parenchyma are strongly coupled. The tree induces an extra viscous term in the system constitutive relation, which leads, in the finite element framework, to a full matrix. We consider an efficient algorithm that takes advantage of the tree structure to enable a fast matrix-vector product computation. This framework can be used to model both free and mechanically induced respiration, in health and disease. Patient-specific lung geometries acquired from computed tomography scans are considered. Realistic Dirichlet boundary conditions can be deduced from surface registration on computed tomography images. The model is compared to a more classical exit compartment approach. Results illustrate the coupling between the tree and the parenchyma, at global and regional levels, and how conditions for the purely 0D model can be inferred. Different types of boundary conditions are tested, including a nonlinear Robin model of the surrounding lung structures. Copyright © 2017 John Wiley & Sons, Ltd.

  10. Guideliness for system modeling: fault tree [analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yoon Hwan; Yang, Joon Eon; Kang, Dae Il; Hwang, Mee Jeong

    2004-07-01

    This document, the guidelines for system modeling related to Fault Tree Analysis(FTA), is intended to provide the guidelines with the analyzer to construct the fault trees in the level of the capability category II of ASME PRA standard. Especially, they are to provide the essential and basic guidelines and the related contents to be used in support of revising the Ulchin 3 and 4 PSA model for risk monitor within the capability category II of ASME PRA standard. Normally the main objective of system analysis is to assess the reliability of system modeled by Event Tree Analysis (ETA). A variety of analytical techniques can be used for the system analysis, however, FTA method is used in this procedures guide. FTA is the method used for representing the failure logic of plant systems deductively using AND, OR or NOT gates. The fault tree should reflect all possible failure modes that may contribute to the system unavailability. This should include contributions due to the mechanical failures of the components, Common Cause Failures (CCFs), human errors and outages for testing and maintenance. This document identifies and describes the definitions and the general procedures of FTA and the essential and basic guidelines for reving the fault trees. Accordingly, the guidelines for FTA will be capable to guide the FTA to the level of the capability category II of ASME PRA standard.

  11. Guideliness for system modeling: fault tree [analysis

    International Nuclear Information System (INIS)

    Lee, Yoon Hwan; Yang, Joon Eon; Kang, Dae Il; Hwang, Mee Jeong

    2004-07-01

    This document, the guidelines for system modeling related to Fault Tree Analysis(FTA), is intended to provide the guidelines with the analyzer to construct the fault trees in the level of the capability category II of ASME PRA standard. Especially, they are to provide the essential and basic guidelines and the related contents to be used in support of revising the Ulchin 3 and 4 PSA model for risk monitor within the capability category II of ASME PRA standard. Normally the main objective of system analysis is to assess the reliability of system modeled by Event Tree Analysis (ETA). A variety of analytical techniques can be used for the system analysis, however, FTA method is used in this procedures guide. FTA is the method used for representing the failure logic of plant systems deductively using AND, OR or NOT gates. The fault tree should reflect all possible failure modes that may contribute to the system unavailability. This should include contributions due to the mechanical failures of the components, Common Cause Failures (CCFs), human errors and outages for testing and maintenance. This document identifies and describes the definitions and the general procedures of FTA and the essential and basic guidelines for reving the fault trees. Accordingly, the guidelines for FTA will be capable to guide the FTA to the level of the capability category II of ASME PRA standard

  12. Use of fault and decision tree analyses to protect against industrial sabotage

    International Nuclear Information System (INIS)

    Fullwood, R.R.; Erdmann, R.C.

    1975-01-01

    Fault tree and decision tree analyses provide systematic bases for evaluation of safety systems and procedures. Heuristically, this paper shows applications of these methods for industrial sabotage analysis at a reprocessing plant. Fault trees constructed by ''leak path'' analysis for completeness through path inventory. The escape fault tree is readily developed by this method and using the reciprocal character of the trees, the attack fault tree is constructed. After construction, the events on the fault tree are corrected for their nonreciprocal character. The fault trees are algebraically solved and the protection that is afforded is ranked by the number of barriers that must be penetrated. No attempt is made to assess the barrier penetration probabilities or penetration time duration. Event trees are useful for dynamic plant protection analysis through their time-sequencing character. To illustrate their usefulness, a simple attack scenario is devised and event-tree analyzed. Two saboteur success paths and 21 failure paths are found. This example clearly shows the event tree usefulness for concisely presenting the time sequencing of key decision points. However, event trees have the disadvantage of being scenario dependent, therefore requiring a separate event tree for each scenario

  13. Quantitative Verification and Synthesis of Attack-Defence Scenarios

    DEFF Research Database (Denmark)

    Aslanyan, Zaruhi; Nielson, Flemming; Parker, David

    2016-01-01

    analysis of quantitative properties of complex attack-defence scenarios, using an extension of attack-defence trees which models temporal ordering of actions and allows explicit dependencies in the strategies adopted by attackers and defenders. We adopt a game-theoretic approach, translating attack...... which guarantee or optimise some quantitative property, such as the probability of a successful attack, the expected cost incurred, or some multi-objective trade-off between the two. We implement our approach, building upon the PRISM-games model checker, and apply it to a case study of an RFID goods...

  14. Verification of Fault Tree Models with RBDGG Methodology

    International Nuclear Information System (INIS)

    Kim, Man Cheol

    2010-01-01

    Currently, fault tree analysis is widely used in the field of probabilistic safety assessment (PSA) of nuclear power plants (NPPs). To guarantee the correctness of fault tree models, which are usually manually constructed by analysts, a review by other analysts is widely used for verifying constructed fault tree models. Recently, an extension of the reliability block diagram was developed, which is named as RBDGG (reliability block diagram with general gates). The advantage of the RBDGG methodology is that the structure of a RBDGG model is very similar to the actual structure of the analyzed system and, therefore, the modeling of a system for a system reliability and unavailability analysis becomes very intuitive and easy. The main idea of the development of the RBDGG methodology is similar to that of the development of the RGGG (Reliability Graph with General Gates) methodology. The difference between the RBDGG methodology and RGGG methodology is that the RBDGG methodology focuses on the block failures while the RGGG methodology focuses on the connection line failures. But, it is also known that an RGGG model can be converted to an RBDGG model and vice versa. In this paper, a new method for the verification of the constructed fault tree models using the RBDGG methodology is proposed and demonstrated

  15. Imitation learning of car driving skills with decision trees and random forests

    Directory of Open Access Journals (Sweden)

    Cichosz Paweł

    2014-09-01

    Full Text Available Machine learning is an appealing and useful approach to creating vehicle control algorithms, both for simulated and real vehicles. One common learning scenario that is often possible to apply is learning by imitation, in which the behavior of an exemplary driver provides training instances for a supervised learning algorithm. This article follows this approach in the domain of simulated car racing, using the TORCS simulator. In contrast to most prior work on imitation learning, a symbolic decision tree knowledge representation is adopted, which combines potentially high accuracy with human readability, an advantage that can be important in many applications. Decision trees are demonstrated to be capable of representing high quality control models, reaching the performance level of sophisticated pre-designed algorithms. This is achieved by enhancing the basic imitation learning scenario to include active retraining, automatically triggered on control failures. It is also demonstrated how better stability and generalization can be achieved by sacrificing human-readability and using decision tree model ensembles. The methodology for learning control models contributed by this article can be hopefully applied to solve real-world control tasks, as well as to develop video game bots

  16. "Growing trees backwards": Description of a stand reconstruction model (P-53)

    Science.gov (United States)

    Jonathan D. Bakker; Andrew J. Sanchez Meador; Peter Z. Fule; David W. Huffman; Margaret M. Moore

    2008-01-01

    We describe an individual-tree model that uses contemporary measurements to "grow trees backward" and reconstruct past tree diameters and stand structure in ponderosa pine dominated stands of the Southwest. Model inputs are contemporary structural measurements of all snags, logs, stumps, and living trees, and radial growth measurements, if available. Key...

  17. Modeling percent tree canopy cover: a pilot study

    Science.gov (United States)

    John W. Coulston; Gretchen G. Moisen; Barry T. Wilson; Mark V. Finco; Warren B. Cohen; C. Kenneth Brewer

    2012-01-01

    Tree canopy cover is a fundamental component of the landscape, and the amount of cover influences fire behavior, air pollution mitigation, and carbon storage. As such, efforts to empirically model percent tree canopy cover across the United States are a critical area of research. The 2001 national-scale canopy cover modeling and mapping effort was completed in 2006,...

  18. A deterministic model for the growth of non-conducting electrical tree structures

    International Nuclear Information System (INIS)

    Dodd, S J

    2003-01-01

    Electrical treeing is of interest to the electrical generation, transmission and distribution industries as it is one of the causes of insulation failure in electrical machines, switchgear and transformer bushings. In this paper a deterministic electrical tree growth model is described. The model is based on electrostatics and local electron avalanches to model partial discharge activity within the growing tree structure. Damage to the resin surrounding the tree structure is dependent on the local electrostatic energy dissipation by partial discharges within the tree structure and weighted by the magnitudes of the local electric fields in the resin surrounding the tree structure. The model is successful in simulating the formation of branched structures without the need of a random variable, a requirement of previous stochastic models. Instability in the spatial development of partial discharges within the tree structure takes the role of the stochastic element as used in previous models to produce branched tree structures. The simulated electrical trees conform to the experimentally observed behaviour; tree length versus time and electrical tree growth rate as a function of applied voltage for non-conducting electrical trees. The phase synchronous partial discharge activity and the spatial distribution of emitted light from the tree structure are also in agreement with experimental data for non-conducting trees as grown in a flexible epoxy resin and in polyethylene. The fact that similar tree growth behaviour is found using pure amorphous (epoxy resin) and semicrystalline (polyethylene) materials demonstrate that neither annealed or quenched noise, representing material inhomogeneity, is required for the formation of irregular branched structures (electrical trees). Instead, as shown in this paper, branched growth can occur due to the instability of individual discharges within the tree structure

  19. Modeling Ecosystem Services for Park Trees: Sensitivity of i-Tree Eco Simulations to Light Exposure and Tree Species Classification

    Directory of Open Access Journals (Sweden)

    Rocco Pace

    2018-02-01

    Full Text Available Ecosystem modeling can help decision making regarding planting of urban trees for climate change mitigation and air pollution reduction. Algorithms and models that link the properties of plant functional types, species groups, or single species to their impact on specific ecosystem services have been developed. However, these models require a considerable effort for initialization that is inherently related to uncertainties originating from the high diversity of plant species in urban areas. We therefore suggest a new automated method to be used with the i-Tree Eco model to derive light competition for individual trees and investigate the importance of this property. Since competition depends also on the species, which is difficult to determine from increasingly used remote sensing methodologies, we also investigate the impact of uncertain tree species classification on the ecosystem services by comparing a species-specific inventory determined by field observation with a genus-specific categorization and a model initialization for the dominant deciduous and evergreen species only. Our results show how the simulation of competition affects the determination of carbon sequestration, leaf area, and related ecosystem services and that the proposed method provides a tool for improving estimations. Misclassifications of tree species can lead to large deviations in estimates of ecosystem impacts, particularly concerning biogenic volatile compound emissions. In our test case, monoterpene emissions almost doubled and isoprene emissions decreased to less than 10% when species were estimated to belong only to either two groups instead of being determined by species or genus. It is discussed that this uncertainty of emission estimates propagates further uncertainty in the estimation of potential ozone formation. Overall, we show the importance of using an individual light competition approach and explicitly parameterizing all ecosystem functions at the

  20. Development of nuclear spent fuel Maritime transportation scenario

    International Nuclear Information System (INIS)

    Yoo, Min; Kang, Hyun Gook

    2014-01-01

    Spent fuel transportation of South Korea is to be conducted through near sea because it is able to ship a large amount of the spent fuel far from the public comparing to overland transportation. The maritime transportation is expected to be increased and its risk has to be assessed. For the risk assessment, this study utilizes the probabilistic safety assessment (PSA) method and the notions of the combined event. Risk assessment of maritime transportation of spent fuel is not well developed in comparison with overland transportation. For the assessment, first, the transportation scenario should be developed and categorized. Categories are assorted into the locations, release aspects and exposure aspects. This study deals with accident that happens on voyage and concentrated on ship-ship collision. The collision accident scenario is generated with event tree analysis. The scenario will be exploited for the maritime transportation risk model which includes consequence and accident probability

  1. Development of nuclear spent fuel Maritime transportation scenario

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Min; Kang, Hyun Gook [KAIST, Daejeon (Korea, Republic of)

    2014-08-15

    Spent fuel transportation of South Korea is to be conducted through near sea because it is able to ship a large amount of the spent fuel far from the public comparing to overland transportation. The maritime transportation is expected to be increased and its risk has to be assessed. For the risk assessment, this study utilizes the probabilistic safety assessment (PSA) method and the notions of the combined event. Risk assessment of maritime transportation of spent fuel is not well developed in comparison with overland transportation. For the assessment, first, the transportation scenario should be developed and categorized. Categories are assorted into the locations, release aspects and exposure aspects. This study deals with accident that happens on voyage and concentrated on ship-ship collision. The collision accident scenario is generated with event tree analysis. The scenario will be exploited for the maritime transportation risk model which includes consequence and accident probability.

  2. Linking definitions, mechanisms, and modeling of drought-induced tree death.

    Science.gov (United States)

    Anderegg, William R L; Berry, Joseph A; Field, Christopher B

    2012-12-01

    Tree death from drought and heat stress is a critical and uncertain component in forest ecosystem responses to a changing climate. Recent research has illuminated how tree mortality is a complex cascade of changes involving interconnected plant systems over multiple timescales. Explicit consideration of the definitions, dynamics, and temporal and biological scales of tree mortality research can guide experimental and modeling approaches. In this review, we draw on the medical literature concerning human death to propose a water resource-based approach to tree mortality that considers the tree as a complex organism with a distinct growth strategy. This approach provides insight into mortality mechanisms at the tree and landscape scales and presents promising avenues into modeling tree death from drought and temperature stress. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Modelling fruit-temperature dynamics within apple tree crowns using virtual plants.

    Science.gov (United States)

    Saudreau, M; Marquier, A; Adam, B; Sinoquet, H

    2011-10-01

    Fruit temperature results from a complex system involving the climate, the tree architecture, the fruit location within the tree crown and the fruit thermal properties. Despite much theoretical and experimental evidence for large differences (up to 10 °C in sunny conditions) between fruit temperature and air temperature, fruit temperature is never used in horticultural studies. A way of modelling fruit-temperature dynamics from climate data is addressed in this work. The model is based upon three-dimensional virtual representation of apple trees and links three-dimensional virtual trees with a physical-based fruit-temperature dynamical model. The overall model was assessed by comparing model outputs to field measures of fruit-temperature dynamics. The model was able to simulate both the temperature dynamics at fruit scale, i.e. fruit-temperature gradients and departure from air temperature, and at the tree scale, i.e. the within-tree-crown variability in fruit temperature (average root mean square error value over fruits was 1·43 °C). This study shows that linking virtual plants with the modelling of the physical plant environment offers a relevant framework to address the modelling of fruit-temperature dynamics within a tree canopy. The proposed model offers opportunities for modelling effects of the within-crown architecture on fruit thermal responses in horticultural studies.

  4. Scenario-based verification of real-time systems using UPPAAL

    DEFF Research Database (Denmark)

    Li, Shuhao; Belaguer, Sandie; David, Alexandre

    2010-01-01

    Abstract This paper proposes two approaches to tool-supported automatic verification of dense real-time systems against scenario-based requirements, where a system is modeled as a network of timed automata (TAs) or as a set of driving live sequence charts (LSCs), and a requirement is specified...... as a separate monitored LSC chart. We make timed extensions to a kernel subset of the LSC language and define a trace-based semantics. By translating a monitored LSC chart to a behavior-equivalent observer TA and then non-intrusively composing this observer with the original TA modeled real-time system......, the problem of scenario-based verification reduces to a computation tree logic (CTL) real-time model checking problem. In case the real time system is modeled as a set of driving LSC charts, we translate these driving charts and the monitored chart into a behavior-equivalent network of TAs by using a “one...

  5. Climatic correlates of tree mortality in water- and energy-limited forests.

    Directory of Open Access Journals (Sweden)

    Adrian J Das

    Full Text Available Recent increases in tree mortality rates across the western USA are correlated with increasing temperatures, but mechanisms remain unresolved. Specifically, increasing mortality could predominantly be a consequence of temperature-induced increases in either (1 drought stress, or (2 the effectiveness of tree-killing insects and pathogens. Using long-term data from California's Sierra Nevada mountain range, we found that in water-limited (low-elevation forests mortality was unambiguously best modeled by climatic water deficit, consistent with the first mechanism. In energy-limited (high-elevation forests deficit models were only equivocally better than temperature models, suggesting that the second mechanism is increasingly important in these forests. We could not distinguish between models predicting mortality using absolute versus relative changes in water deficit, and these two model types led to different forecasts of mortality vulnerability under future climate scenarios. Our results provide evidence for differing climatic controls of tree mortality in water- and energy-limited forests, while highlighting the need for an improved understanding of tree mortality processes.

  6. Tree Mortality Undercuts Ability of Tree-Planting Programs to Provide Benefits: Results of a Three-City Study

    Directory of Open Access Journals (Sweden)

    Sarah Widney

    2016-03-01

    Full Text Available Trees provide numerous benefits for urban residents, including reduced energy usage, improved air quality, stormwater management, carbon sequestration, and increased property values. Quantifying these benefits can help justify the costs of planting trees. In this paper, we use i-Tree Streets to quantify the benefits of street trees planted by nonprofits in three U.S. cities (Detroit, Michigan; Indianapolis, Indiana, and Philadelphia, Pennsylvania from 2009 to 2011. We also use both measured and modeled survival and growth rates to “grow” the tree populations 5 and 10 years into the future to project the future benefits of the trees under different survival and growth scenarios. The 4059 re-inventoried trees (2864 of which are living currently provide almost $40,000 (USD in estimated annual benefits ($9–$20/tree depending on the city, the majority (75% of which are increased property values. The trees can be expected to provide increasing annual benefits during the 10 years after planting if the annual survival rate is higher than the 93% annual survival measured during the establishment period. However, our projections show that with continued 93% or lower annual survival, the increase in annual benefits from tree growth will not be able to make up for the loss of benefits as trees die. This means that estimated total annual benefits from a cohort of planted trees will decrease between the 5-year projection and the 10-year projection. The results of this study indicate that without early intervention to ensure survival of planted street trees, tree mortality may be significantly undercutting the ability of tree-planting programs to provide benefits to neighborhood residents.

  7. Predictive integrated modelling for ITER scenarios

    International Nuclear Information System (INIS)

    Artaud, J.F.; Imbeaux, F.; Aniel, T.; Basiuk, V.; Eriksson, L.G.; Giruzzi, G.; Hoang, G.T.; Huysmans, G.; Joffrin, E.; Peysson, Y.; Schneider, M.; Thomas, P.

    2005-01-01

    The uncertainty on the prediction of ITER scenarios is evaluated. 2 transport models which have been extensively validated against the multi-machine database are used for the computation of the transport coefficients. The first model is GLF23, the second called Kiauto is a model in which the profile of dilution coefficient is a gyro Bohm-like analytical function, renormalized in order to get profiles consistent with a given global energy confinement scaling. The package of codes CRONOS is used, it gives access to the dynamics of the discharge and allows the study of interplay between heat transport, current diffusion and sources. The main motivation of this work is to study the influence of parameters such plasma current, heat, density, impurities and toroidal moment transport. We can draw the following conclusions: 1) the target Q = 10 can be obtained in ITER hybrid scenario at I p = 13 MA, using either the DS03 two terms scaling or the GLF23 model based on the same pedestal; 2) I p = 11.3 MA, Q = 10 can be reached only assuming a very peaked pressure profile and a low pedestal; 3) at fixed Greenwald fraction, Q increases with density peaking; 4) achieving a stationary q-profile with q > 1 requires a large non-inductive current fraction (80%) that could be provided by 20 to 40 MW of LHCD; and 5) owing to the high temperature the q-profile penetration is delayed and q = 1 is reached about 600 s in ITER hybrid scenario at I p = 13 MA, in the absence of active q-profile control. (A.C.)

  8. Total tree, merchantable stem and branch volume models for ...

    African Journals Online (AJOL)

    Total tree, merchantable stem and branch volume models for miombo woodlands of Malawi. Daud J Kachamba, Tron Eid. Abstract. The objective of this study was to develop general (multispecies) models for prediction of total tree, merchantable stem and branch volume including options with diameter at breast height (dbh) ...

  9. Modeling Future Land Use Scenarios in South Korea: Applying the IPCC Special Report on Emissions Scenarios and the SLEUTH Model on a Local Scale

    Science.gov (United States)

    Han, Haejin; Hwang, YunSeop; Ha, Sung Ryong; Kim, Byung Sik

    2015-05-01

    This study developed three scenarios of future land use/land cover on a local level for the Kyung-An River Basin and its vicinity in South Korea at a 30-m resolution based on the two scenario families of the Intergovernmental Panel on Climate Change (IPCC) Special Report Emissions Scenarios (SRES): A2 and B1, as well as a business-as-usual scenario. The IPCC SRES A2 and B1 were used to define future local development patterns and associated land use change. We quantified the population-driven demand for urban land use for each qualitative storyline and allocated the urban demand in geographic space using the SLEUTH model. The model results demonstrate the possible land use/land cover change scenarios for the years from 2000 to 2070 by examining the broad narrative of each SRES within the context of a local setting, such as the Kyoungan River Basin, constructing narratives of local development shifts and modeling a set of `best guess' approximations of the future land use conditions in the study area. This study found substantial differences in demands and patterns of land use changes among the scenarios, indicating compact development patterns under the SRES B1 compared to the rapid and dispersed development under the SRES A2.

  10. Modeling future land use scenarios in South Korea: applying the IPCC special report on emissions scenarios and the SLEUTH model on a local scale.

    Science.gov (United States)

    Han, Haejin; Hwang, YunSeop; Ha, Sung Ryong; Kim, Byung Sik

    2015-05-01

    This study developed three scenarios of future land use/land cover on a local level for the Kyung-An River Basin and its vicinity in South Korea at a 30-m resolution based on the two scenario families of the Intergovernmental Panel on Climate Change (IPCC) Special Report Emissions Scenarios (SRES): A2 and B1, as well as a business-as-usual scenario. The IPCC SRES A2 and B1 were used to define future local development patterns and associated land use change. We quantified the population-driven demand for urban land use for each qualitative storyline and allocated the urban demand in geographic space using the SLEUTH model. The model results demonstrate the possible land use/land cover change scenarios for the years from 2000 to 2070 by examining the broad narrative of each SRES within the context of a local setting, such as the Kyoungan River Basin, constructing narratives of local development shifts and modeling a set of 'best guess' approximations of the future land use conditions in the study area. This study found substantial differences in demands and patterns of land use changes among the scenarios, indicating compact development patterns under the SRES B1 compared to the rapid and dispersed development under the SRES A2.

  11. The Prediction of Drought-Related Tree Mortality in Vegetation Models

    Science.gov (United States)

    Schwinning, S.; Jensen, J.; Lomas, M. R.; Schwartz, B.; Woodward, F. I.

    2013-12-01

    Drought-related tree die-off events at regional scales have been reported from all wooded continents and it has been suggested that their frequency may be increasing. The prediction of these drought-related die-off events from regional to global scales has been recognized as a critical need for the conservation of forest resources and improving the prediction of climate-vegetation interactions. However, there is no conceptual consensus on how to best approach the quantitative prediction of tree mortality. Current models use a variety of mechanisms to represent demographic events. Mortality is modeled to represent a number of different processes, including death by fire, wind throw, extreme temperatures, and self-thinning, and each vegetation model differs in the emphasis they place on specific mechanisms. Dynamic global vegetation models generally operate on the assumption of incremental vegetation shift due to changes in the carbon economy of plant functional types and proportional effects on recruitment, growth, competition and mortality, but this may not capture sudden and sweeping tree death caused by extreme weather conditions. We tested several different approaches to predicting tree mortality within the framework of the Sheffield Dynamic Global Vegetation Model. We applied the model to the state of Texas, USA, which in 2011 experienced extreme drought conditions, causing the death of an estimated 300 million trees statewide. We then compared predicted to actual mortality to determine which algorithms most accurately predicted geographical variation in tree mortality. We discuss implications regarding the ongoing debate on the causes of tree death.

  12. Scenario Analysis With Economic-Energy Systems Models Coupled to Simple Climate Models

    Science.gov (United States)

    Hanson, D. A.; Kotamarthi, V. R.; Foster, I. T.; Franklin, M.; Zhu, E.; Patel, D. M.

    2008-12-01

    Here, we compare two scenarios based on Stanford University's Energy Modeling Forum Study 22 on global cooperative and non-cooperative climate policies. In the former, efficient transition paths are implemented including technology Research and Development effort, energy conservation programs, and price signals for greenhouse gas (GHG) emissions. In the non-cooperative case, some countries try to relax their regulations and be free riders. Total emissions and costs are higher in the non-cooperative scenario. The simulations, including climate impacts, run to the year 2100. We use the Argonne AMIGA-MARS economic-energy systems model, the Texas AM University's Forest and Agricultural Sector Optimization Model (FASOM), and the University of Illinois's Integrated Science Assessment Model (ISAM), with offline coupling between the FASOM and AMIGA-MARS and an online coupling between AMIGA-MARS and ISAM. This set of models captures the interaction of terrestrial systems, land use, crops and forests, climate change, human activity, and energy systems. Our scenario simulations represent dynamic paths over which all the climate, terrestrial, economic, and energy technology equations are solved simultaneously Special attention is paid to biofuels and how they interact with conventional gasoline/diesel fuel markets. Possible low-carbon penetration paths are based on estimated costs for new technologies, including cellulosic biomass, coal-to-liquids, plug-in electric vehicles, solar and nuclear energy. We explicitly explore key uncertainties that affect mitigation and adaptation scenarios.

  13. Fruit tree model for uptake of organic compounds from soil

    DEFF Research Database (Denmark)

    Trapp, Stefan; Rasmussen, D.; Samsoe-Petersen, L.

    2003-01-01

    -state, and an example calculation is given. The Fruit Tree Model is compared to the empirical equation of Travis and Arms (T&A), and to results from fruits, collected in contaminated areas. For polar compounds, both T&A and the Fruit Tree Model predict bioconcentration factors fruit to soil (BCF, wet weight based......) of > 1. No empirical data are available to support this prediction. For very lipophilic compounds (log K-OW > 5), T&A overestimates the uptake. The conclusion from the Fruit Tree Model is that the transfer of lipophilic compounds into fruits is not relevant. This was also found by an empirical study...... with PCDD/F. According to the Fruit Tree Model, polar chemicals are transferred efficiently into fruits, but empirical data to verify these predictions are lacking....

  14. Tree shrew (Tupaia belangeri as a novel laboratory disease animal model

    Directory of Open Access Journals (Sweden)

    Ji Xiao

    2017-05-01

    Full Text Available The tree shrew (Tupaia belangeri is a promising laboratory animal that possesses a closer genetic relationship to primates than to rodents. In addition, advantages such as small size, easy breeding, and rapid reproduction make the tree shrew an ideal subject for the study of human disease. Numerous tree shrew disease models have been generated in biological and medical studies in recent years. Here we summarize current tree shrew disease models, including models of infectious diseases, cancers, depressive disorders, drug addiction, myopia, metabolic diseases, and immune-related diseases. With the success of tree shrew transgenic technology, this species will be increasingly used in biological and medical studies in the future.

  15. Parameter identification in multinomial processing tree models

    NARCIS (Netherlands)

    Schmittmann, V.D.; Dolan, C.V.; Raijmakers, M.E.J.; Batchelder, W.H.

    2010-01-01

    Multinomial processing tree models form a popular class of statistical models for categorical data that have applications in various areas of psychological research. As in all statistical models, establishing which parameters are identified is necessary for model inference and selection on the basis

  16. Waste Isolation Safety Assessment Program scenario analysis methods for use in assessing the safety of the geologic isolation of nuclear waste

    International Nuclear Information System (INIS)

    Greenborg, J.; Winegardner, W.K.; Pelto, P.J.; Voss, J.W.; Stottlemyre, J.A.; Forbes, I.A.; Fussell, J.B.; Burkholder, H.C.

    1978-11-01

    The relative utility of the various safety analysis methods to scenario analysis for a repository system was evaluated by judging the degree to which certain criteria are satisfied by use of the method. Six safety analysis methods were reviewed in this report for possible use in scenario analysis of nuclear waste repositories: expert opinion, perspectives analysis, fault trees/event trees, Monte Carlo simulation, Markov chains, and classical systems analysis. Four criteria have been selected. The criteria suggest that the methods: (1) be quantitative and scientifically based; (2) model the potential disruptive events and processes, (3) model the system before and after failure (sufficiently detailed to provide for subsequent consequence analysis); and (4) be compatible with the level of available system knowledge and data. Expert opinion, fault trees/event trees, Monte Carlo simulation and classical systems analysis were judged to have the greatest potential appliation to the problem of scenario analysis. The methods were found to be constrained by limited data and by knowledge of the processes governing the system. It was determined that no single method is clearly superior to others when measured against all the criteria. Therefore, to get the best understanding of system behavior, a combination of the methods is recommended. Monte Carlo simulation was judged to be the most suitable matrix in which to incorporate a combination of methods

  17. Component-based modeling of systems for automated fault tree generation

    International Nuclear Information System (INIS)

    Majdara, Aref; Wakabayashi, Toshio

    2009-01-01

    One of the challenges in the field of automated fault tree construction is to find an efficient modeling approach that can support modeling of different types of systems without ignoring any necessary details. In this paper, we are going to represent a new system of modeling approach for computer-aided fault tree generation. In this method, every system model is composed of some components and different types of flows propagating through them. Each component has a function table that describes its input-output relations. For the components having different operational states, there is also a state transition table. Each component can communicate with other components in the system only through its inputs and outputs. A trace-back algorithm is proposed that can be applied to the system model to generate the required fault trees. The system modeling approach and the fault tree construction algorithm are applied to a fire sprinkler system and the results are presented

  18. Systematic evaluation of fault trees using real-time model checker UPPAAL

    International Nuclear Information System (INIS)

    Cha, Sungdeok; Son, Hanseong; Yoo, Junbeom; Jee, Eunkyung; Seong, Poong Hyun

    2003-01-01

    Fault tree analysis, the most widely used safety analysis technique in industry, is often applied manually. Although techniques such as cutset analysis or probabilistic analysis can be applied on the fault tree to derive further insights, they are inadequate in locating flaws when failure modes in fault tree nodes are incorrectly identified or when causal relationships among failure modes are inaccurately specified. In this paper, we demonstrate that model checking technique is a powerful tool that can formally validate the accuracy of fault trees. We used a real-time model checker UPPAAL because the system we used as the case study, nuclear power emergency shutdown software named Wolsong SDS2, has real-time requirements. By translating functional requirements written in SCR-style tabular notation into timed automata, two types of properties were verified: (1) if failure mode described in a fault tree node is consistent with the system's behavioral model; and (2) whether or not a fault tree node has been accurately decomposed. A group of domain engineers with detailed technical knowledge of Wolsong SDS2 and safety analysis techniques developed fault tree used in the case study. However, model checking technique detected subtle ambiguities present in the fault tree

  19. Development and application of a tree-code in simulation scenarios of the plasma-wall interaction; Entwicklung und Anwendung eines Tree-Codes in Simulationsszenarios der Plasma-Wand-Wechselwirkung

    Energy Technology Data Exchange (ETDEWEB)

    Berberich, Benjamin

    2012-03-15

    Processes in the plasma edge layer of magnetic fusion devices occur on widely disparate length- and time-scales. Also recently developed features in this particular region, such as stochastic magnetic fields, underline the necessity for three dimensional, full-kinetic simulation tools. Contemporary programs often deploy ad hoc assumptions and approximations for microscopic phenomena for which self-consistent ab initio models in principle exist, but are still computationally too expensive or complex to implement. Recently, mesh-free methods have matured into a new class of tools for such first-principles computations which thanks to their geometric flexibility are highly promising for tackling complicated TOKAMAK regions. In this work we have develop the massively parallel Tree-Code PEPC-B (Pretty Efficient Parallel Coulomb solver) into a new tool for plasma material interaction studies. After a brief overview of the working principles of Tree-Codes two main topic groups are addressed: First the leap-frog Boris integration scheme is discussed and its numerical limitations are pointed out. To overcome these limitations the method is enhanced to a guiding-center integrator. As a proof of principal, numerical experiments are conducted reproducing the anticipated drift kinetic aspects of particle orbits. It turns out that this new technique is much less sensitive to large time steps than the original concept was. One major drawback of mesh-free methods which hinders their direct use for plasma-edge simulations is the difficulty in representing solid structures and associated boundary conditions. Therefore, an alternative concept is proposed using charge carrying Wall-Particles, which fits naturally in the mesh-free doctrine. These developments incorporate the second main topic group of this report. To prove the physical correctness of this new idea, a quasi one dimensional plasma-wall interface scenario is chosen. By studying the system with great detail, good agreement

  20. Based on user interest level of modeling scenarios and browse content

    Science.gov (United States)

    Zhao, Yang

    2017-08-01

    User interest modeling is the core of personalized service, taking into account the impact of situational information on user preferences, the user behavior days of financial information. This paper proposes a method of user interest modeling based on scenario information, which is obtained by calculating the similarity of the situation. The user's current scene of the approximate scenario set; on the "user - interest items - scenarios" three-dimensional model using the situation pre-filtering method of dimension reduction processing. View the content of the user interested in the theme, the analysis of the page content to get each topic of interest keywords, based on the level of vector space model user interest. The experimental results show that the user interest model based on the scenario information is within 9% of the user's interest prediction, which is effective.

  1. Bridging process-based and empirical approaches to modeling tree growth

    Science.gov (United States)

    Harry T. Valentine; Annikki Makela; Annikki Makela

    2005-01-01

    The gulf between process-based and empirical approaches to modeling tree growth may be bridged, in part, by the use of a common model. To this end, we have formulated a process-based model of tree growth that can be fitted and applied in an empirical mode. The growth model is grounded in pipe model theory and an optimal control model of crown development. Together, the...

  2. Modular techniques for dynamic fault-tree analysis

    Science.gov (United States)

    Patterson-Hine, F. A.; Dugan, Joanne B.

    1992-01-01

    It is noted that current approaches used to assess the dependability of complex systems such as Space Station Freedom and the Air Traffic Control System are incapable of handling the size and complexity of these highly integrated designs. A novel technique for modeling such systems which is built upon current techniques in Markov theory and combinatorial analysis is described. It enables the development of a hierarchical representation of system behavior which is more flexible than either technique alone. A solution strategy which is based on an object-oriented approach to model representation and evaluation is discussed. The technique is virtually transparent to the user since the fault tree models can be built graphically and the objects defined automatically. The tree modularization procedure allows the two model types, Markov and combinatoric, to coexist and does not require that the entire fault tree be translated to a Markov chain for evaluation. This effectively reduces the size of the Markov chain required and enables solutions with less truncation, making analysis of longer mission times possible. Using the fault-tolerant parallel processor as an example, a model is built and solved for a specific mission scenario and the solution approach is illustrated in detail.

  3. 3D Visualization of Trees Based on a Sphere-Board Model

    Directory of Open Access Journals (Sweden)

    Jiangfeng She

    2018-01-01

    Full Text Available Because of the smooth interaction of tree systems, the billboard and crossed-plane techniques of image-based rendering (IBR have been used for tree visualization for many years. However, both the billboard-based tree model (BBTM and the crossed-plane tree model (CPTM have several notable limitations; for example, they give an impression of slicing when viewed from the top side, and they produce an unimpressive stereoscopic effect and insufficient lighted effects. In this study, a sphere-board-based tree model (SBTM is proposed to eliminate these defects and to improve the final visual effects. Compared with the BBTM or CPTM, the proposed SBTM uses one or more sphere-like 3D geometric surfaces covered with a virtual texture, which can present more details about the foliage than can 2D planes, to represent the 3D outline of a tree crown. However, the profile edge presented by a continuous surface is overly smooth and regular, and when used to delineate the outline of a tree crown, it makes the tree appear very unrealistic. To overcome this shortcoming and achieve a more natural final visual effect of the tree model, an additional process is applied to the edge of the surface profile. In addition, the SBTM can better support lighted effects because of its cubic geometrical features. Interactive visualization effects for a single tree and a grove are presented in a case study of Sabina chinensis. The results show that the SBTM can achieve a better compromise between realism and performance than can the BBTM or CPTM.

  4. Water-Tree Modelling and Detection for Underground Cables

    Science.gov (United States)

    Chen, Qi

    In recent years, aging infrastructure has become a major concern for the power industry. Since its inception in early 20th century, the electrical system has been the cornerstone of an industrial society. Stable and uninterrupted delivery of electrical power is now a base necessity for the modern world. As the times march-on, however, the electrical infrastructure ages and there is the inevitable need to renew and replace the existing system. Unfortunately, due to time and financial constraints, many electrical systems today are forced to operate beyond their original design and power utilities must find ways to prolong the lifespan of older equipment. Thus, the concept of preventative maintenance arises. Preventative maintenance allows old equipment to operate longer and at better efficiency, but in order to implement preventative maintenance, the operators must know minute details of the electrical system, especially some of the harder to assess issues such water-tree. Water-tree induced insulation degradation is a problem typically associated with older cable systems. It is a very high impedance phenomenon and it is difficult to detect using traditional methods such as Tan-Delta or Partial Discharge. The proposed dissertation studies water-tree development in underground cables, potential methods to detect water-tree location and water-tree severity estimation. The dissertation begins by developing mathematical models of water-tree using finite element analysis. The method focuses on surface-originated vented tree, the most prominent type of water-tree fault in the field. Using the standard operation parameters of North American electrical systems, the water-tree boundary conditions are defined. By applying finite element analysis technique, the complex water-tree structure is broken down to homogeneous components. The result is a generalized representation of water-tree capacitance at different stages of development. The result from the finite element analysis

  5. Development of Accident Scenarios and Quantification Methodology for RAON Accelerator

    International Nuclear Information System (INIS)

    Lee, Yongjin; Jae, Moosung

    2014-01-01

    The RIsp (Rare Isotope Science Project) plans to provide neutron-rich isotopes (RIs) and stable heavy ion beams. The accelerator is defined as radiation production system according to Nuclear Safety Law. Therefore, it needs strict operate procedures and safety assurance to prevent radiation exposure. In order to satisfy this condition, there is a need for evaluating potential risk of accelerator from the design stage itself. Though some of PSA researches have been conducted for accelerator, most of them focus on not general accident sequence but simple explanation of accident. In this paper, general accident scenarios are developed by Event Tree and deduce new quantification methodology of Event Tree. In this study, some initial events, which may occur in the accelerator, are selected. Using selected initial events, the accident scenarios of accelerator facility are developed with Event Tree. These results can be used as basic data of the accelerator for future risk assessments. After analyzing the probability of each heading, it is possible to conduct quantification and evaluate the significance of the accident result. If there is a development of the accident scenario for external events, risk assessment of entire accelerator facility will be completed. To reduce the uncertainty of the Event Tree, it is possible to produce a reliable data via the presented quantification techniques

  6. Discrete dynamic event tree modeling and analysis of nuclear power plant crews for safety assessment

    International Nuclear Information System (INIS)

    Mercurio, D.

    2011-01-01

    Current Probabilistic Risk Assessment (PRA) and Human Reliability Analysis (HRA) methodologies model the evolution of accident sequences in Nuclear Power Plants (NPPs) mainly based on Logic Trees. The evolution of these sequences is a result of the interactions between the crew and plant; in current PRA methodologies, simplified models of these complex interactions are used. In this study, the Accident Dynamic Simulator (ADS), a modeling framework based on the Discrete Dynamic Event Tree (DDET), has been used for the simulation of crew-plant interactions during potential accident scenarios in NPPs. In addition, an operator/crew model has been developed to treat the response of the crew to the plant. The 'crew model' is made up of three operators whose behavior is guided by a set of rules-of-behavior (which represents the knowledge and training of the operators) coupled with written and mental procedures. In addition, an approach for addressing the crew timing variability in DDETs has been developed and implemented based on a set of HRA data from a simulator study. Finally, grouping techniques were developed and applied to the analysis of the scenarios generated by the crew-plant simulation. These techniques support the post-simulation analysis by grouping similar accident sequences, identifying the key contributing events, and quantifying the conditional probability of the groups. These techniques are used to characterize the context of the crew actions in order to obtain insights for HRA. The model has been applied for the analysis of a Small Loss Of Coolant Accident (SLOCA) event for a Pressurized Water Reactor (PWR). The simulation results support an improved characterization of the performance conditions or context of operator actions, which can be used in an HRA, in the analysis of the reliability of the actions. By providing information on the evolution of system indications, dynamic of cues, crew timing in performing procedure steps, situation

  7. A stochastic Forest Fire Model for future land cover scenarios assessment

    Directory of Open Access Journals (Sweden)

    M. D'Andrea

    2010-10-01

    Full Text Available Land cover is affected by many factors including economic development, climate and natural disturbances such as wildfires. The ability to evaluate how fire regimes may alter future vegetation, and how future vegetation may alter fire regimes, would assist forest managers in planning management actions to be carried out in the face of anticipated socio-economic and climatic change. In this paper, we present a method for calibrating a cellular automata wildfire regime simulation model with actual data on land cover and wildfire size-frequency. The method is based on the observation that many forest fire regimes, in different forest types and regions, exhibit power law frequency-area distributions. The standard Drossel-Schwabl cellular automata Forest Fire Model (DS-FFM produces simulations which reproduce this observed pattern. However, the standard model is simplistic in that it considers land cover to be binary – each cell either contains a tree or it is empty – and the model overestimates the frequency of large fires relative to actual landscapes. Our new model, the Modified Forest Fire Model (MFFM, addresses this limitation by incorporating information on actual land use and differentiating among various types of flammable vegetation. The MFFM simulation model was tested on forest types with Mediterranean and sub-tropical fire regimes. The results showed that the MFFM was able to reproduce structural fire regime parameters for these two regions. Further, the model was used to forecast future land cover. Future research will extend this model to refine the forecasts of future land cover and fire regime scenarios under climate, land use and socio-economic change.

  8. Probabilistic construction of inflow scenarios at a reservoir; Construction probabiliste de scenarios d'apports a un reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Seidou, O.; Robert, B.; Marche, C.; Rousselle, J. [Ecole Polytechnique de Montreal, Departement des Genies Civil, Geologique et des Mines, Montreal, PQ (Canada); Lefebvre, M. [Ecole Polytechnique de Montreal, Departement de Mathematiques et de Genie Industriel, Montreal, PQ (Canada)

    2004-02-01

    Development of risk indicators to aid in decisions affecting the operation of hydric systems is described. The significant part of the risk affecting hydric systems is the uncertainty surrounding future inflows. A method to construct inflow scenarios starting from an arbitrary date 'y' of the year is developed using a Markovian process which also has been used to model short-term uncertainty in stream flow. The text is divided in five parts: (1) methodology, (2) terminology, (3) theory, (4) application, and (5) results. The scenarios are built to reproduce the statistical behaviour of the river or reservoir and have the shape of an event tree whose structure is defined by the user before application of the method. Application of the method is illustrated by two examples, one involving the Harricana River, the other the Cabonga Reservoir, both situated in the province of Quebec. 11 refs., 4 tabs., 4 figs.

  9. BIOMOVS test scenario model comparison using BIOPATH

    International Nuclear Information System (INIS)

    Grogan, H.A.; Van Dorp, F.

    1986-07-01

    This report presents the results of the irrigation test scenario, presented in the BIOMOVS intercomparison study, calculated by the computer code BIOPATH. This scenario defines a constant release of Tc-99 and Np-237 into groundwater that is used for irrigation. The system of compartments used to model the biosphere is based upon an area in northern Switzerland and is essentially the same as that used in Projekt Gewaehr to assess the radiological impact of a high level waste repository. Two separate irrigation methods are considered, namely ditch and overhead irrigation. Their influence on the resultant activities calculated in the groundwater, soil and different foodproducts, as a function of time, is evaluated. The sensitivity of the model to parameter variations is analysed which allows a deeper understanding of the model chain. These results are assessed subjectively in a first effort to realistically quantify the uncertainty associated with each calculated activity. (author)

  10. A homeostatic-partly dynamic model for 137Cs in trees

    International Nuclear Information System (INIS)

    Frissel, M.

    1994-01-01

    A model has been developed to describe the behaviour of 137 Cs in trees. The core of the model is the assumption that 137 Cs/K ratio in soil determines the 137 Cs/K ratio in various parts of a tree. This is an equilibrium model but taking into account the time dependence of Cs/K ratio in the soil (caused by K-fertilization) it has been extended to a dynamic model. The model desribes a growing tree. Four compartments are considered: soil; easily accessible parts of the tree; woody parts difficult to access; fruits or leaves. The model is homeostatic, i.e. all 137 Cs concentrations and fluxes are controlled by K concentrations and fluxes, respectively. The addition of K-fertilizer to the soil manifests itself in an immediate change of the Cs/K ratio in the soil and in the easily accessible plant parts, but only slowly - in the woody parts. Also an excess of Cs in the woody part is only slowly released. Important processes are the discrimination between Cs and K and the luxurious consumption of K. The cycling of K in the system (throughput of K via falling leaves, branches, etc.) is also important. Furthermore, a good insight in accessibility of the various parts of the tree seems required, the division in only three compartments, as in the model is probably unsufficient. (author)

  11. Accident scenarios triggered by lightning strike on atmospheric storage tanks

    International Nuclear Information System (INIS)

    Necci, Amos; Argenti, Francesca; Landucci, Gabriele; Cozzani, Valerio

    2014-01-01

    Severe Natech accidents may be triggered by lightning strike affecting storage tanks containing relevant inventories of hazardous materials. The present study focused on the identification of event sequences and accident scenarios following lightning impact on atmospheric tanks. Reference event trees, validated using past accident analysis, are provided to describe the specific accident chains identified, accounting for reference protection and mitigation safety barriers usually adopted in current industrial practice. An overall methodology was outlined to allow the calculation of the expected frequencies of final scenarios following lightning impact on atmospheric storage tanks, taking into account the expected performance of available safety barriers. The methodology was applied to a case study in order to better understand the data that may be obtained and their importance in the framework of quantitative risk assessment (QRA) and of the risk management of industrial facilities with respect to external hazards due to natural events. - Highlights: • Event sequences following lightning impact on atmospheric tanks were identified. • Reference event trees including standard safety barriers were obtained. • Safety barriers applied in industrial practice were assessed to quantify event trees. • Frequencies of final scenarios following lightning impact on tanks were calculated. • Natech scenarios caused by lightning have an important influence on risk profiles

  12. Pareto Efficient Solution of Attack-Defence Trees

    NARCIS (Netherlands)

    Aslanyan, Zaruhi; Nielson, Flemming

    Attack-defence trees are a promising approach for representing threat scenarios and possible countermeasures in a concise and intuitive manner. An attack-defence tree describes the interaction between an attacker and a defender, and is evaluated by assigning parameters to the nodes, such as

  13. The shape and temporal dynamics of phylogenetic trees arising from geographic speciation.

    Science.gov (United States)

    Pigot, Alex L; Phillimore, Albert B; Owens, Ian P F; Orme, C David L

    2010-12-01

    Phylogenetic trees often depart from the expectations of stochastic models, exhibiting imbalance in diversification among lineages and slowdowns in the rate of lineage accumulation through time. Such departures have led to a widespread perception that ecological differences among species or adaptation and subsequent niche filling are required to explain patterns of diversification. However, a key element missing from models of diversification is the geographical context of speciation and extinction. In this study, we develop a spatially explicit model of geographic range evolution and cladogenesis, where speciation arises via vicariance or peripatry, and explore the effects of these processes on patterns of diversification. We compare the results with those observed in 41 reconstructed avian trees. Our model shows that nonconstant rates of speciation and extinction are emergent properties of the apportioning of geographic ranges that accompanies speciation. The dynamics of diversification exhibit wide variation, depending on the mode of speciation, tendency for range expansion, and rate of range evolution. By varying these parameters, the model is able to capture many, but not all, of the features exhibited by birth-death trees and extant bird clades. Under scenarios with relatively stable geographic ranges, strong slowdowns in diversification rates are produced, with faster rates of range dynamics leading to constant or accelerating rates of apparent diversification. A peripatric model of speciation with stable ranges also generates highly unbalanced trees typical of bird phylogenies but fails to produce realistic range size distributions among the extant species. Results most similar to those of a birth-death process are reached under a peripatric speciation scenario with highly volatile range dynamics. Taken together, our results demonstrate that considering the geographical context of speciation and extinction provides a more conservative null model of

  14. A stochastic model of nanoparticle self-assembly on Cayley trees

    International Nuclear Information System (INIS)

    Mazilu, I; Schwen, E M; Banks, W E; Pope, B K; Mazilu, D A

    2015-01-01

    Nanomedicine is an emerging area of medical research that uses innovative nanotechnologies to improve the delivery of therapeutic and diagnostic agents with maximum clinical benefit. We present a versatile stochastic model that can be used to capture the basic features of drug encapsulation of nanoparticles on tree-like synthetic polymers called dendrimers. The geometry of a dendrimer is described mathematically as a Cayley tree. We use our stochastic model to study the dynamics of deposition and release of monomers (simulating the drug molecules) on Cayley trees (simulating dendrimers). We present analytical and Monte Carlo simulation results for the particle density on Cayley trees of coordination number three and four

  15. Selection bias in species distribution models: An econometric approach on forest trees based on structural modeling

    Science.gov (United States)

    Martin-StPaul, N. K.; Ay, J. S.; Guillemot, J.; Doyen, L.; Leadley, P.

    2014-12-01

    Species distribution models (SDMs) are widely used to study and predict the outcome of global changes on species. In human dominated ecosystems the presence of a given species is the result of both its ecological suitability and human footprint on nature such as land use choices. Land use choices may thus be responsible for a selection bias in the presence/absence data used in SDM calibration. We present a structural modelling approach (i.e. based on structural equation modelling) that accounts for this selection bias. The new structural species distribution model (SSDM) estimates simultaneously land use choices and species responses to bioclimatic variables. A land use equation based on an econometric model of landowner choices was joined to an equation of species response to bioclimatic variables. SSDM allows the residuals of both equations to be dependent, taking into account the possibility of shared omitted variables and measurement errors. We provide a general description of the statistical theory and a set of applications on forest trees over France using databases of climate and forest inventory at different spatial resolution (from 2km to 8km). We also compared the outputs of the SSDM with outputs of a classical SDM (i.e. Biomod ensemble modelling) in terms of bioclimatic response curves and potential distributions under current climate and climate change scenarios. The shapes of the bioclimatic response curves and the modelled species distribution maps differed markedly between SSDM and classical SDMs, with contrasted patterns according to species and spatial resolutions. The magnitude and directions of these differences were dependent on the correlations between the errors from both equations and were highest for higher spatial resolutions. A first conclusion is that the use of classical SDMs can potentially lead to strong miss-estimation of the actual and future probability of presence modelled. Beyond this selection bias, the SSDM we propose represents

  16. Discrete Discriminant analysis based on tree-structured graphical models

    DEFF Research Database (Denmark)

    Perez de la Cruz, Gonzalo; Eslava, Guillermina

    The purpose of this paper is to illustrate the potential use of discriminant analysis based on tree{structured graphical models for discrete variables. This is done by comparing its empirical performance using estimated error rates for real and simulated data. The results show that discriminant a...... analysis based on tree{structured graphical models is a simple nonlinear method competitive with, and sometimes superior to, other well{known linear methods like those assuming mutual independence between variables and linear logistic regression.......The purpose of this paper is to illustrate the potential use of discriminant analysis based on tree{structured graphical models for discrete variables. This is done by comparing its empirical performance using estimated error rates for real and simulated data. The results show that discriminant...

  17. Biomass models to estimate carbon stocks for hardwood tree species

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Peinado, R.; Montero, G.; Rio, M. del

    2012-11-01

    To estimate forest carbon pools from forest inventories it is necessary to have biomass models or biomass expansion factors. In this study, tree biomass models were developed for the main hardwood forest species in Spain: Alnus glutinosa, Castanea sativa, Ceratonia siliqua, Eucalyptus globulus, Fagus sylvatica, Fraxinus angustifolia, Olea europaea var. sylvestris, Populus x euramericana, Quercus canariensis, Quercus faginea, Quercus ilex, Quercus pyrenaica and Quercus suber. Different tree biomass components were considered: stem with bark, branches of different sizes, above and belowground biomass. For each species, a system of equations was fitted using seemingly unrelated regression, fulfilling the additivity property between biomass components. Diameter and total height were explored as independent variables. All models included tree diameter whereas for the majority of species, total height was only considered in the stem biomass models and in some of the branch models. The comparison of the new biomass models with previous models fitted separately for each tree component indicated an improvement in the accuracy of the models. A mean reduction of 20% in the root mean square error and a mean increase in the model efficiency of 7% in comparison with recently published models. So, the fitted models allow estimating more accurately the biomass stock in hardwood species from the Spanish National Forest Inventory data. (Author) 45 refs.

  18. The Studies of Decision Tree in Estimation of Breast Cancer Risk by Using Polymorphism Nucleotide

    Directory of Open Access Journals (Sweden)

    Frida Seyedmir

    2017-07-01

    Full Text Available Abstract Introduction:   Decision tree is the data mining tools to collect, accurate prediction and sift information from massive amounts of data that are used widely in the field of computational biology and bioinformatics. In bioinformatics can be predict on diseases, including breast cancer. The use of genomic data including single nucleotide polymorphisms is a very important factor in predicting the risk of diseases. The number of seven important SNP among hundreds of thousands genetic markers were identified as factors associated with breast cancer. The objective of this study is to evaluate the training data on decision tree predictor error of the risk of breast cancer by using single nucleotide polymorphism genotype. Methods: The risk of breast cancer were calculated associated with the use of SNP formula:xj = fo * In human,  The decision tree can be used To predict the probability of disease using single nucleotide polymorphisms .Seven SNP with different odds ratio associated with breast cancer considered and coding and design of decision tree model, C4.5, by  Csharp2013 programming language were done. In the decision tree created with the coding, the four important associated SNP was considered. The decision tree error in two case of coding and using WEKA were assessment and percentage of decision tree accuracy in prediction of breast cancer were calculated. The number of trained samples was obtained with systematic sampling. With coding, two scenarios as well as software WEKA, three scenarios with different sets of data and the number of different learning and testing, were evaluated. Results: In both scenarios of coding, by increasing the training percentage from 66/66 to 86/42, the error reduced from 55/56 to 9/09. Also by running of WEKA on three scenarios with different sets of data, the number of different education, and different tests by increasing records number from 81 to 2187, the error rate decreased from 48/15 to 13

  19. Contrasting safety assessments of a runway incursion scenario: Event sequence analysis versus multi-agent dynamic risk modelling

    International Nuclear Information System (INIS)

    Stroeve, Sybert H.; Blom, Henk A.P.; Bakker, G.J.

    2013-01-01

    In the safety literature it has been argued, that in a complex socio-technical system safety cannot be well analysed by event sequence based approaches, but requires to capture the complex interactions and performance variability of the socio-technical system. In order to evaluate the quantitative and practical consequences of these arguments, this study compares two approaches to assess accident risk of an example safety critical sociotechnical system. It contrasts an event sequence based assessment with a multi-agent dynamic risk model (MA-DRM) based assessment, both of which are performed for a particular runway incursion scenario. The event sequence analysis uses the well-known event tree modelling formalism and the MA-DRM based approach combines agent based modelling, hybrid Petri nets and rare event Monte Carlo simulation. The comparison addresses qualitative and quantitative differences in the methods, attained risk levels, and in the prime factors influencing the safety of the operation. The assessments show considerable differences in the accident risk implications of the performance of human operators and technical systems in the runway incursion scenario. In contrast with the event sequence based results, the MA-DRM based results show that the accident risk is not manifest from the performance of and relations between individual human operators and technical systems. Instead, the safety risk emerges from the totality of the performance and interactions in the agent based model of the safety critical operation considered, which coincides very well with the argumentation in the safety literature.

  20. Forward modeling of tree-ring data: a case study with a global network

    Science.gov (United States)

    Breitenmoser, P. D.; Frank, D.; Brönnimann, S.

    2012-04-01

    Information derived from tree-rings is one of the most powerful tools presently available for studying past climatic variability as well as identifying fundamental relationships between tree-growth and climate. Climate reconstructions are typically performed by extending linear relationships, established during the overlapping period of instrumental and climate proxy archives into the past. Such analyses, however, are limited by methodological assumptions, including stationarity and linearity of the climate-proxy relationship. We investigate climate and tree-ring data using the Vaganov-Shashkin-Lite (VS-Lite) forward model of tree-ring width formation to examine the relations among actual tree growth and climate (as inferred from the simulated chronologies) to reconstruct past climate variability. The VS-lite model has been shown to produce skill comparable to that achieved using classical dendrochronological statistical modeling techniques when applied on simulations of a network of North American tree-ring chronologies. Although the detailed mechanistic processes such as photosynthesis, storage, or cell processes are not modeled directly, the net effect of the dominating nonlinear climatic controls on tree-growth are implemented into the model by the principle of limiting factors and threshold growth response functions. The VS-lite model requires as inputs only latitude, monthly mean temperature and monthly accumulated precipitation. Hence, this simple, process-based model enables ring-width simulation at any location where monthly climate records exist. In this study, we analyse the growth response of simulated tree-rings to monthly climate conditions obtained from the 20th century reanalysis project back to 1871. These simulated tree-ring chronologies are compared to the climate-driven variability in worldwide observed tree-ring chronologies from the International Tree Ring Database. Results point toward the suitability of the relationship among actual tree

  1. Modeling the Ecosystem Services Provided by Trees in Urban Ecosystems: Using Biome-BGC to Improve i-Tree Eco

    Science.gov (United States)

    Brown, Molly E.; McGroddy, Megan; Spence, Caitlin; Flake, Leah; Sarfraz, Amna; Nowak, David J.; Milesi, Cristina

    2012-01-01

    As the world becomes increasingly urban, the need to quantify the effect of trees in urban environments on energy usage, air pollution, local climate and nutrient run-off has increased. By identifying, quantifying and valuing the ecological activity that provides services in urban areas, stronger policies and improved quality of life for urban residents can be obtained. Here we focus on two radically different models that can be used to characterize urban forests. The i-Tree Eco model (formerly UFORE model) quantifies ecosystem services (e.g., air pollution removal, carbon storage) and values derived from urban trees based on field measurements of trees and local ancillary data sets. Biome-BGC (Biome BioGeoChemistry) is used to simulate the fluxes and storage of carbon, water, and nitrogen in natural environments. This paper compares i-Tree Eco's methods to those of Biome-BGC, which estimates the fluxes and storage of energy, carbon, water and nitrogen for vegetation and soil components of the ecosystem. We describe the two models and their differences in the way they calculate similar properties, with a focus on carbon and nitrogen. Finally, we discuss the implications of further integration of these two communities for land managers such as those in Maryland.

  2. Isoprene Emission Factors for Subtropical Street Trees for Regional Air Quality Modeling.

    Science.gov (United States)

    Dunn-Johnston, Kristina A; Kreuzwieser, Jürgen; Hirabayashi, Satoshi; Plant, Lyndal; Rennenberg, Heinz; Schmidt, Susanne

    2016-01-01

    Evaluating the environmental benefits and consequences of urban trees supports their sustainable management in cities. Models such as i-Tree Eco enable decision-making by quantifying effects associated with particular tree species. Of specific concern are emissions of biogenic volatile organic compounds, particularly isoprene, that contribute to the formation of photochemical smog and ground level ozone. Few studies have quantified these potential disservices of urban trees, and current models predominantly use emissions data from trees that differ from those in our target region of subtropical Australia. The present study aimed (i) to quantify isoprene emission rates of three tree species that together represent 16% of the inventoried street trees in the target region; (ii) to evaluate outputs of the i-Tree Eco model using species-specific versus currently used, generic isoprene emission rates; and (iii) to evaluate the findings in the context of regional air quality. Isoprene emission rates of (Myrtaceae) and (Proteaceae) were 2.61 and 2.06 µg g dry leaf weight h, respectively, whereas (Sapindaceae) was a nonisoprene emitter. We substituted the generic isoprene emission rates with these three empirical values in i-Tree Eco, resulting in a 182 kg yr (97%) reduction in isoprene emissions, totaling 6284 kg yr when extrapolated to the target region. From these results we conclude that care has to be taken when using generic isoprene emission factors for urban tree models. We recommend that emissions be quantified for commonly planted trees, allowing decision-makers to select tree species with the greatest overall benefit for the urban environment. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  3. Hierarchical models for informing general biomass equations with felled tree data

    Science.gov (United States)

    Brian J. Clough; Matthew B. Russell; Christopher W. Woodall; Grant M. Domke; Philip J. Radtke

    2015-01-01

    We present a hierarchical framework that uses a large multispecies felled tree database to inform a set of general models for predicting tree foliage biomass, with accompanying uncertainty, within the FIA database. Results suggest significant prediction uncertainty for individual trees and reveal higher errors when predicting foliage biomass for larger trees and for...

  4. A framework for modeling scenario-based barrier island storm impacts

    Science.gov (United States)

    Mickey, Rangley; Long, Joseph W.; Dalyander, P. Soupy; Plant, Nathaniel G.; Thompson, David M.

    2018-01-01

    Methods for investigating the vulnerability of existing or proposed coastal features to storm impacts often rely on simplified parametric models or one-dimensional process-based modeling studies that focus on changes to a profile across a dune or barrier island. These simple studies tend to neglect the impacts to curvilinear or alongshore varying island planforms, influence of non-uniform nearshore hydrodynamics and sediment transport, irregular morphology of the offshore bathymetry, and impacts from low magnitude wave events (e.g. cold fronts). Presented here is a framework for simulating regionally specific, low and high magnitude scenario-based storm impacts to assess the alongshore variable vulnerabilities of a coastal feature. Storm scenarios based on historic hydrodynamic conditions were derived and simulated using the process-based morphologic evolution model XBeach. Model results show that the scenarios predicted similar patterns of erosion and overwash when compared to observed qualitative morphologic changes from recent storm events that were not included in the dataset used to build the scenarios. The framework model simulations were capable of predicting specific areas of vulnerability in the existing feature and the results illustrate how this storm vulnerability simulation framework could be used as a tool to help inform the decision-making process for scientists, engineers, and stakeholders involved in coastal zone management or restoration projects.

  5. Analysis of global warming stabilization scenarios. The Asian-Pacific Integrated Model

    International Nuclear Information System (INIS)

    Kainuma, Mikiko; Morita, Tsuneyuki; Masui, Toshihiko; Takahashi, Kiyoshi; Matsuoka, Yuzuru

    2004-01-01

    This paper analyzes the economic and climatic impacts of the EMF 19 emission scenarios. A reference scenario, three emission scenarios targeting 550 ppmv atmospheric concentration, and three tax scenarios are analyzed. The profiles of energy consumption and economic losses of each policy scenario are compared to the reference scenario. The model also estimates that global mean temperature will increase 1.7-2.9 C in 2100, and the sea level will rise 40-51 cm, compared to the 1990 levels under the EMF scenarios. Impacts on food productivity and malaria infection are estimated to be very severe in some countries in the Asian region

  6. MRI-based decision tree model for diagnosis of biliary atresia.

    Science.gov (United States)

    Kim, Yong Hee; Kim, Myung-Joon; Shin, Hyun Joo; Yoon, Haesung; Han, Seok Joo; Koh, Hong; Roh, Yun Ho; Lee, Mi-Jung

    2018-02-23

    To evaluate MRI findings and to generate a decision tree model for diagnosis of biliary atresia (BA) in infants with jaundice. We retrospectively reviewed features of MRI and ultrasonography (US) performed in infants with jaundice between January 2009 and June 2016 under approval of the institutional review board, including the maximum diameter of periportal signal change on MRI (MR triangular cord thickness, MR-TCT) or US (US-TCT), visibility of common bile duct (CBD) and abnormality of gallbladder (GB). Hepatic subcapsular flow was reviewed on Doppler US. We performed conditional inference tree analysis using MRI findings to generate a decision tree model. A total of 208 infants were included, 112 in the BA group and 96 in the non-BA group. Mean age at the time of MRI was 58.7 ± 36.6 days. Visibility of CBD, abnormality of GB and MR-TCT were good discriminators for the diagnosis of BA and the MRI-based decision tree using these findings with MR-TCT cut-off 5.1 mm showed 97.3 % sensitivity, 94.8 % specificity and 96.2 % accuracy. MRI-based decision tree model reliably differentiates BA in infants with jaundice. MRI can be an objective imaging modality for the diagnosis of BA. • MRI-based decision tree model reliably differentiates biliary atresia in neonatal cholestasis. • Common bile duct, gallbladder and periportal signal changes are the discriminators. • MRI has comparable performance to ultrasonography for diagnosis of biliary atresia.

  7. Particle Reduction Strategies - PAREST. Traffic emission modelling. Model comparision and alternative scenarios. Sub-report

    International Nuclear Information System (INIS)

    Kugler, Ulrike; Theloke, Jochen; Joerss, Wolfram

    2013-01-01

    The modeling of the reference scenario and the various reduction scenarios in PAREST was based on the Central System of Emissions (CSE) (CSE, 2007). Emissions from road traffic were calculated by using the traffic emission model TREMOD (Knoerr et al., 2005) and fed into the CSE. The version TREMOD 4.17 has been used. The resulting emission levels in PAREST reference scenario were supplemented by the emission-reducing effect of the implementation of the future Euro 5 and 6 emission standards for cars and light commercial vehicles and Euro VI for heavy commercial vehicles in combination with the truck toll extension. [de

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

    Science.gov (United States)

    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.

  9. Modeling the effects of tree species and incubation temperature on soil's extracellular enzyme activity in 78-year-old tree plantations

    Science.gov (United States)

    Zhou, Xiaoqi; Wang, Shen S. J.; Chen, Chengrong

    2017-12-01

    Forest plantations have been widely used as an effective measure for increasing soil carbon (C), and nitrogen (N) stocks and soil enzyme activities play a key role in soil C and N losses during decomposition of soil organic matter. However, few studies have been carried out to elucidate the mechanisms behind the differences in soil C and N cycling by different tree species in response to climate warming. Here, we measured the responses of soil's extracellular enzyme activity (EEA) to a gradient of temperatures using incubation methods in 78-year-old forest plantations with different tree species. Based on a soil enzyme kinetics model, we established a new statistical model to investigate the effects of temperature and tree species on soil EEA. In addition, we established a tree species-enzyme-C/N model to investigate how temperature and tree species influence soil C/N contents over time without considering plant C inputs. These extracellular enzymes included C acquisition enzymes (β-glucosidase, BG), N acquisition enzymes (N-acetylglucosaminidase, NAG; leucine aminopeptidase, LAP) and phosphorus acquisition enzymes (acid phosphatases). The results showed that incubation temperature and tree species significantly influenced all soil EEA and Eucalyptus had 1.01-2.86 times higher soil EEA than coniferous tree species. Modeling showed that Eucalyptus had larger soil C losses but had 0.99-2.38 times longer soil C residence time than the coniferous tree species over time. The differences in the residual soil C and N contents between Eucalyptus and coniferous tree species, as well as between slash pine (Pinus elliottii Engelm. var. elliottii) and hoop pine (Araucaria cunninghamii Ait.), increase with time. On the other hand, the modeling results help explain why exotic slash pine can grow faster, as it has 1.22-1.38 times longer residual soil N residence time for LAP, which mediate soil N cycling in the long term, than native coniferous tree species like hoop pine and

  10. Modeling the effects of tree species and incubation temperature on soil's extracellular enzyme activity in 78-year-old tree plantations

    Directory of Open Access Journals (Sweden)

    X. Zhou

    2017-12-01

    Full Text Available Forest plantations have been widely used as an effective measure for increasing soil carbon (C, and nitrogen (N stocks and soil enzyme activities play a key role in soil C and N losses during decomposition of soil organic matter. However, few studies have been carried out to elucidate the mechanisms behind the differences in soil C and N cycling by different tree species in response to climate warming. Here, we measured the responses of soil's extracellular enzyme activity (EEA to a gradient of temperatures using incubation methods in 78-year-old forest plantations with different tree species. Based on a soil enzyme kinetics model, we established a new statistical model to investigate the effects of temperature and tree species on soil EEA. In addition, we established a tree species–enzyme–C∕N model to investigate how temperature and tree species influence soil C∕N contents over time without considering plant C inputs. These extracellular enzymes included C acquisition enzymes (β-glucosidase, BG, N acquisition enzymes (N-acetylglucosaminidase, NAG; leucine aminopeptidase, LAP and phosphorus acquisition enzymes (acid phosphatases. The results showed that incubation temperature and tree species significantly influenced all soil EEA and Eucalyptus had 1.01–2.86 times higher soil EEA than coniferous tree species. Modeling showed that Eucalyptus had larger soil C losses but had 0.99–2.38 times longer soil C residence time than the coniferous tree species over time. The differences in the residual soil C and N contents between Eucalyptus and coniferous tree species, as well as between slash pine (Pinus elliottii Engelm. var. elliottii and hoop pine (Araucaria cunninghamii Ait., increase with time. On the other hand, the modeling results help explain why exotic slash pine can grow faster, as it has 1.22–1.38 times longer residual soil N residence time for LAP, which mediate soil N cycling in the long term, than native

  11. Biomass Scenario Model Documentation: Data and References

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Y.; Newes, E.; Bush, B.; Peterson, S.; Stright, D.

    2013-05-01

    The Biomass Scenario Model (BSM) is a system dynamics model that represents the entire biomass-to-biofuels supply chain, from feedstock to fuel use. The BSM is a complex model that has been used for extensive analyses; the model and its results can be better understood if input data used for initialization and calibration are well-characterized. It has been carefully validated and calibrated against the available data, with data gaps filled in using expert opinion and internally consistent assumed values. Most of the main data sources that feed into the model are recognized as baseline values by the industry. This report documents data sources and references in Version 2 of the BSM (BSM2), which only contains the ethanol pathway, although subsequent versions of the BSM contain multiple conversion pathways. The BSM2 contains over 12,000 total input values, with 506 distinct variables. Many of the variables are opportunities for the user to define scenarios, while others are simply used to initialize a stock, such as the initial number of biorefineries. However, around 35% of the distinct variables are defined by external sources, such as models or reports. The focus of this report is to provide insight into which sources are most influential in each area of the supply chain.

  12. Workflow Fault Tree Generation Through Model Checking

    DEFF Research Database (Denmark)

    Herbert, Luke Thomas; Sharp, Robin

    2014-01-01

    We present a framework for the automated generation of fault trees from models of realworld process workflows, expressed in a formalised subset of the popular Business Process Modelling and Notation (BPMN) language. To capture uncertainty and unreliability in workflows, we extend this formalism...

  13. Global warming factors modelled for 40 generic municipal waste management scenarios

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Simion, F.; Tonini, Davide

    2009-01-01

    Global warming factors (kg CO2-eq.-tonne—1 of waste) have been modelled for 40 different municipal waste management scenarios involving a variety of recycling systems (paper, glass, plastic and organics) and residual waste management by landfilling, incineration or mechanical—biological waste...... treatment. For average European waste composition most waste management scenarios provided negative global warming factors and hence overall savings in greenhouse gas emissions: Scenarios with landfilling saved 0—400, scenarios with incineration saved 200—700, and scenarios with mechanical...

  14. Climate change impacts on tree ranges: model intercomparison facilitates understanding and quantification of uncertainty.

    Science.gov (United States)

    Cheaib, Alissar; Badeau, Vincent; Boe, Julien; Chuine, Isabelle; Delire, Christine; Dufrêne, Eric; François, Christophe; Gritti, Emmanuel S; Legay, Myriam; Pagé, Christian; Thuiller, Wilfried; Viovy, Nicolas; Leadley, Paul

    2012-06-01

    Model-based projections of shifts in tree species range due to climate change are becoming an important decision support tool for forest management. However, poorly evaluated sources of uncertainty require more scrutiny before relying heavily on models for decision-making. We evaluated uncertainty arising from differences in model formulations of tree response to climate change based on a rigorous intercomparison of projections of tree distributions in France. We compared eight models ranging from niche-based to process-based models. On average, models project large range contractions of temperate tree species in lowlands due to climate change. There was substantial disagreement between models for temperate broadleaf deciduous tree species, but differences in the capacity of models to account for rising CO(2) impacts explained much of the disagreement. There was good quantitative agreement among models concerning the range contractions for Scots pine. For the dominant Mediterranean tree species, Holm oak, all models foresee substantial range expansion. © 2012 Blackwell Publishing Ltd/CNRS.

  15. Integrating land use and climate change scenarios and models into assessment of forested watershed services in Southern Thailand.

    Science.gov (United States)

    Trisurat, Yongyut; Eawpanich, Piyathip; Kalliola, Risto

    2016-05-01

    The Thadee watershed, covering 112km(2), is the main source of water for agriculture and household consumption in the Nakhon Srithammarat Province in Southern Thailand. As the natural forests upstream have been largely degraded and transformed to fruit tree and rubber plantations, problems with landslides and flooding have resulted. This research attempts to predict how further land-use/land-cover changes during 2009-2020 and conceivable changes in rainfall may influence the future levels of water yield and sediment load in the Thadee River. Three different land use scenarios (trend, development and conservation) were defined in collaboration with the local stakeholders, and three different rainfall scenarios (average rainfall, climate change and extreme wet) were determined on the basis of literature sources. Spatially explicit empirical modelling was employed to allocate future land demands and to assess the contributions of land use and rainfall changes, considering both their separate and combined effects. The results suggest that substantial land use changes may occur from a large expansion of rubber plantations in the upper sub-watersheds, especially under the development land use scenario. The reduction of the current annual rainfall by approximately 30% would decrease the predicted water yields by 38% from 2009. According to the extreme rainfall scenario (an increase of 36% with respect to current rainfall), an amplification of 50% of the current runoff could result. Sensitivity analyses showed that the predicted soil loss is more responsive to changes in rainfall than to the compared land use scenarios alone. However, very high sediment load and runoff levels were predicted on the basis of combined intensified land use and extreme rainfall scenarios. Three conservation activities-protection, reforestation and a mixed-cropping system-are proposed to maintain the functional watershed services of the Thadee watershed region. Copyright © 2016 Elsevier Inc

  16. Model-Based Military Scenario Management for Defence Capability

    National Research Council Canada - National Science Library

    Gori, Ronnie; Chen, Pin; Pozgay, Angela

    2004-01-01

    .... This paper describes initial work towards the development of an information model that links scenario and capability related information, and the results of capability analysis and experimentation...

  17. Reversible polymorphism-aware phylogenetic models and their application to tree inference.

    Science.gov (United States)

    Schrempf, Dominik; Minh, Bui Quang; De Maio, Nicola; von Haeseler, Arndt; Kosiol, Carolin

    2016-10-21

    We present a reversible Polymorphism-Aware Phylogenetic Model (revPoMo) for species tree estimation from genome-wide data. revPoMo enables the reconstruction of large scale species trees for many within-species samples. It expands the alphabet of DNA substitution models to include polymorphic states, thereby, naturally accounting for incomplete lineage sorting. We implemented revPoMo in the maximum likelihood software IQ-TREE. A simulation study and an application to great apes data show that the runtimes of our approach and standard substitution models are comparable but that revPoMo has much better accuracy in estimating trees, divergence times and mutation rates. The advantage of revPoMo is that an increase of sample size per species improves estimations but does not increase runtime. Therefore, revPoMo is a valuable tool with several applications, from speciation dating to species tree reconstruction. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  18. High-resolution gravity and seismic-refraction surveys of the Smoke Tree Wash area, Joshua Tree National Park, California

    Science.gov (United States)

    Langenheim, Victoria E.; Rymer, Michael J.; Catchings, Rufus D.; Goldman, Mark R.; Watt, Janet T.; Powell, Robert E.; Matti, Jonathan C.

    2016-03-02

    We describe high-resolution gravity and seismic refraction surveys acquired to determine the thickness of valley-fill deposits and to delineate geologic structures that might influence groundwater flow beneath the Smoke Tree Wash area in Joshua Tree National Park. These surveys identified a sedimentary basin that is fault-controlled. A profile across the Smoke Tree Wash fault zone reveals low gravity values and seismic velocities that coincide with a mapped strand of the Smoke Tree Wash fault. Modeling of the gravity data reveals a basin about 2–2.5 km long and 1 km wide that is roughly centered on this mapped strand, and bounded by inferred faults. According to the gravity model the deepest part of the basin is about 270 m, but this area coincides with low velocities that are not characteristic of typical basement complex rocks. Most likely, the density contrast assumed in the inversion is too high or the uncharacteristically low velocities represent highly fractured or weathered basement rocks, or both. A longer seismic profile extending onto basement outcrops would help differentiate which scenario is more accurate. The seismic velocities also determine the depth to water table along the profile to be about 40–60 m, consistent with water levels measured in water wells near the northern end of the profile.

  19. Modeling and validation of directional reflectance for heterogeneous agro-forestry scenarios

    Science.gov (United States)

    Yelu, Z.; Jing, L.; Qinhuo, L.; Huete, A. R.

    2015-12-01

    Landscape heterogeneity is a common natural phenomenon but is seldom considered in current radiative transfer models for predicting the surface reflectance. This paper developed an explicit analytical Radiative Transfer model for heterogeneous Agro-Forestry scenarios (RTAF) by dividing the scenario into non-boundary regions and boundary regions. The scattering contribution of the non-boundary regions that are treated as homogeneous canopies can be estimated from the SAILH model, whereas that of the boundary regions with lengths, widths, canopy heights, and orientations of the field patches, is calculated based on the bidirectional gap probability by considering the interactions and mutual shadowing effects among different patches. The hot spot factor is extended for heterogeneous scenarios, the Hapke model for soil anisotropy is incorporated, and the contributions of the direct and diffuse radiation are separately calculated. The multi-angular airborne observations and the Discrete Anisotropic Radiative Transfer (DART) model simulations were used for validating and evaluating the RTAF model over an agro-forestry scenario in Heihe River Basin, China. It indicates that the RTAF model can accurately simulate the hemispherical-directional reflectance factors (HDRFs) of the heterogeneous agro-forestry scenario, with an RMSE of 0.0016 and 0.0179 in the red and near-infrared (NIR) bands, respectively. The RTAF model was compared with two widely used models, the dominant cover type (DCT) model and the spectral linear mixture (SLM) model, which either neglected the interactions and mutual shadowing effects between the shelterbets and crops, or did not account for the contribution of the shelterbets. Results suggest that the boundary effect can significantly influence the angular distribution of the HDRFs, and consequently enlarged the HDRF variations between the backward and forward directions in the principle plane. The RTAF model reduced the maximum relative error from 25

  20. Anomalous diffusion in a lattice-gas wind-tree model

    International Nuclear Information System (INIS)

    Kong, X.P.; Cohen, E.G.D.

    1989-01-01

    Two new strictly deterministic lattice-gas automata derived from Ehrenfest's wind-tree model are studied. While in one model normal diffusion occurs, the other model exhibits abnormal diffusion in that the distribution function of the displacements of the wind particle is non-Gaussian, but its second moment, the mean-square displacement, is proportional to the time, so that a diffusion coefficient can be defined. A connection with the percolation problem and a self-avoiding random walk for the case in which the lattice is completely covered with trees is discussed

  1. Recruiting Conventional Tree Architecture Models into State-of-the-Art LiDAR Mapping for Investigating Tree Growth Habits in Structure.

    Science.gov (United States)

    Lin, Yi; Jiang, Miao; Pellikka, Petri; Heiskanen, Janne

    2018-01-01

    Mensuration of tree growth habits is of considerable importance for understanding forest ecosystem processes and forest biophysical responses to climate changes. However, the complexity of tree crown morphology that is typically formed after many years of growth tends to render it a non-trivial task, even for the state-of-the-art 3D forest mapping technology-light detection and ranging (LiDAR). Fortunately, botanists have deduced the large structural diversity of tree forms into only a limited number of tree architecture models, which can present a-priori knowledge about tree structure, growth, and other attributes for different species. This study attempted to recruit Hallé architecture models (HAMs) into LiDAR mapping to investigate tree growth habits in structure. First, following the HAM-characterized tree structure organization rules, we run the kernel procedure of tree species classification based on the LiDAR-collected point clouds using a support vector machine classifier in the leave-one-out-for-cross-validation mode. Then, the HAM corresponding to each of the classified tree species was identified based on expert knowledge, assisted by the comparison of the LiDAR-derived feature parameters. Next, the tree growth habits in structure for each of the tree species were derived from the determined HAM. In the case of four tree species growing in the boreal environment, the tests indicated that the classification accuracy reached 85.0%, and their growth habits could be derived by qualitative and quantitative means. Overall, the strategy of recruiting conventional HAMs into LiDAR mapping for investigating tree growth habits in structure was validated, thereby paving a new way for efficiently reflecting tree growth habits and projecting forest structure dynamics.

  2. Context Tree Estimation in Variable Length Hidden Markov Models

    OpenAIRE

    Dumont, Thierry

    2011-01-01

    We address the issue of context tree estimation in variable length hidden Markov models. We propose an estimator of the context tree of the hidden Markov process which needs no prior upper bound on the depth of the context tree. We prove that the estimator is strongly consistent. This uses information-theoretic mixture inequalities in the spirit of Finesso and Lorenzo(Consistent estimation of the order for Markov and hidden Markov chains(1990)) and E.Gassiat and S.Boucheron (Optimal error exp...

  3. Failure rate modeling using fault tree analysis and Bayesian network: DEMO pulsed operation turbine study case

    International Nuclear Information System (INIS)

    Dongiovanni, Danilo Nicola; Iesmantas, Tomas

    2016-01-01

    Highlights: • RAMI (Reliability, Availability, Maintainability and Inspectability) assessment of secondary heat transfer loop for a DEMO nuclear fusion plant. • Definition of a fault tree for a nuclear steam turbine operated in pulsed mode. • Turbine failure rate models update by mean of a Bayesian network reflecting the fault tree analysis in the considered scenario. • Sensitivity analysis on system availability performance. - Abstract: Availability will play an important role in the Demonstration Power Plant (DEMO) success from an economic and safety perspective. Availability performance is commonly assessed by Reliability Availability Maintainability Inspectability (RAMI) analysis, strongly relying on the accurate definition of system components failure modes (FM) and failure rates (FR). Little component experience is available in fusion application, therefore requiring the adaptation of literature FR to fusion plant operating conditions, which may differ in several aspects. As a possible solution to this problem, a new methodology to extrapolate/estimate components failure rate under different operating conditions is presented. The DEMO Balance of Plant nuclear steam turbine component operated in pulse mode is considered as study case. The methodology moves from the definition of a fault tree taking into account failure modes possibly enhanced by pulsed operation. The fault tree is then translated into a Bayesian network. A statistical model for the turbine system failure rate in terms of subcomponents’ FR is hence obtained, allowing for sensitivity analyses on the structured mixture of literature and unknown FR data for which plausible value intervals are investigated to assess their impact on the whole turbine system FR. Finally, the impact of resulting turbine system FR on plant availability is assessed exploiting a Reliability Block Diagram (RBD) model for a typical secondary cooling system implementing a Rankine cycle. Mean inherent availability

  4. Failure rate modeling using fault tree analysis and Bayesian network: DEMO pulsed operation turbine study case

    Energy Technology Data Exchange (ETDEWEB)

    Dongiovanni, Danilo Nicola, E-mail: danilo.dongiovanni@enea.it [ENEA, Nuclear Fusion and Safety Technologies Department, via Enrico Fermi 45, Frascati 00040 (Italy); Iesmantas, Tomas [LEI, Breslaujos str. 3 Kaunas (Lithuania)

    2016-11-01

    Highlights: • RAMI (Reliability, Availability, Maintainability and Inspectability) assessment of secondary heat transfer loop for a DEMO nuclear fusion plant. • Definition of a fault tree for a nuclear steam turbine operated in pulsed mode. • Turbine failure rate models update by mean of a Bayesian network reflecting the fault tree analysis in the considered scenario. • Sensitivity analysis on system availability performance. - Abstract: Availability will play an important role in the Demonstration Power Plant (DEMO) success from an economic and safety perspective. Availability performance is commonly assessed by Reliability Availability Maintainability Inspectability (RAMI) analysis, strongly relying on the accurate definition of system components failure modes (FM) and failure rates (FR). Little component experience is available in fusion application, therefore requiring the adaptation of literature FR to fusion plant operating conditions, which may differ in several aspects. As a possible solution to this problem, a new methodology to extrapolate/estimate components failure rate under different operating conditions is presented. The DEMO Balance of Plant nuclear steam turbine component operated in pulse mode is considered as study case. The methodology moves from the definition of a fault tree taking into account failure modes possibly enhanced by pulsed operation. The fault tree is then translated into a Bayesian network. A statistical model for the turbine system failure rate in terms of subcomponents’ FR is hence obtained, allowing for sensitivity analyses on the structured mixture of literature and unknown FR data for which plausible value intervals are investigated to assess their impact on the whole turbine system FR. Finally, the impact of resulting turbine system FR on plant availability is assessed exploiting a Reliability Block Diagram (RBD) model for a typical secondary cooling system implementing a Rankine cycle. Mean inherent availability

  5. Approximate dynamic fault tree calculations for modelling water supply risks

    International Nuclear Information System (INIS)

    Lindhe, Andreas; Norberg, Tommy; Rosén, Lars

    2012-01-01

    Traditional fault tree analysis is not always sufficient when analysing complex systems. To overcome the limitations dynamic fault tree (DFT) analysis is suggested in the literature as well as different approaches for how to solve DFTs. For added value in fault tree analysis, approximate DFT calculations based on a Markovian approach are presented and evaluated here. The approximate DFT calculations are performed using standard Monte Carlo simulations and do not require simulations of the full Markov models, which simplifies model building and in particular calculations. It is shown how to extend the calculations of the traditional OR- and AND-gates, so that information is available on the failure probability, the failure rate and the mean downtime at all levels in the fault tree. Two additional logic gates are presented that make it possible to model a system's ability to compensate for failures. This work was initiated to enable correct analyses of water supply risks. Drinking water systems are typically complex with an inherent ability to compensate for failures that is not easily modelled using traditional logic gates. The approximate DFT calculations are compared to results from simulations of the corresponding Markov models for three water supply examples. For the traditional OR- and AND-gates, and one gate modelling compensation, the errors in the results are small. For the other gate modelling compensation, the error increases with the number of compensating components. The errors are, however, in most cases acceptable with respect to uncertainties in input data. The approximate DFT calculations improve the capabilities of fault tree analysis of drinking water systems since they provide additional and important information and are simple and practically applicable.

  6. Pareto Efficient Solutions of Attack-Defence Trees

    DEFF Research Database (Denmark)

    Aslanyan, Zaruhi; Nielson, Flemming

    2015-01-01

    Attack-defence trees are a promising approach for representing threat scenarios and possible countermeasures in a concise and intuitive manner. An attack-defence tree describes the interaction between an attacker and a defender, and is evaluated by assigning parameters to the nodes, such as proba......Attack-defence trees are a promising approach for representing threat scenarios and possible countermeasures in a concise and intuitive manner. An attack-defence tree describes the interaction between an attacker and a defender, and is evaluated by assigning parameters to the nodes......, such as probability or cost of attacks and defences. In case of multiple parameters most analytical methods optimise one parameter at a time, e.g., minimise cost or maximise probability of an attack. Such methods may lead to sub-optimal solutions when optimising conflicting parameters, e.g., minimising cost while...... maximising probability. In order to tackle this challenge, we devise automated techniques that optimise all parameters at once. Moreover, in the case of conflicting parameters our techniques compute the set of all optimal solutions, defined in terms of Pareto efficiency. The developments are carried out...

  7. Methods for Developing Emissions Scenarios for Integrated Assessment Models

    Energy Technology Data Exchange (ETDEWEB)

    Prinn, Ronald [MIT; Webster, Mort [MIT

    2007-08-20

    The overall objective of this research was to contribute data and methods to support the future development of new emissions scenarios for integrated assessment of climate change. Specifically, this research had two main objectives: 1. Use historical data on economic growth and energy efficiency changes, and develop probability density functions (PDFs) for the appropriate parameters for two or three commonly used integrated assessment models. 2. Using the parameter distributions developed through the first task and previous work, we will develop methods of designing multi-gas emission scenarios that usefully span the joint uncertainty space in a small number of scenarios. Results on the autonomous energy efficiency improvement (AEEI) parameter are summarized, an uncertainty analysis of elasticities of substitution is described, and the probabilistic emissions scenario approach is presented.

  8. SCENARIO OF AN ACCIDENT OF SOIL DAMS IN CASE OF WATER SPILL OVER A DAM CREST BY USING FAULT TREE ANALYSIS

    Directory of Open Access Journals (Sweden)

    Kuznetsov Dmitriy Viktorovich

    2016-04-01

    Full Text Available The scenario of a hydrodynamic accident of water flow over a crest of a soil dam is considered by the method of fault tree analysis, for which the basic reasons and controlled diagnostic indicators of an accident have been defined. Logical operators “AND”/”OR” were used for creation of a sequence of logically connected events, leading to an undesired event in the scenario of accident. The scenario of the accident was plotted in case of three basic reasons - an excessive settling of a dam crest, an excess flood, an inoperable spillway, taking into account the sequence of the events’ development and with observance of the necessary conditions leading to an accident. “Technical” reasons were observed in the present scenario, force majeure events were not considered. The provided scenario of the accident consists of two branches of events’ development: the left one that depends on an upstream level, and the right one that depends on settling of a dam crest. In each of the considered events an accident “the water spill over a crest of a soil dam” is possible only in case of execution of two different conditions at the same time, i.e. in case of an appropriate upstream level and the appropriate mark of a crest of a soil dam. The conditions of the accident are defined by diagnostic indices - the upstream level and settling of a dam crest, which at the same time are safety criteria of the hydraulic structure for soil dams. They allow defining the technical condition of the construction. Four possible technical conditions are suggested for the definition of technical statuses - normative, operable, limited operable, abnormal. Criteria of safety are the boundaries of the state: for loading and impact - it is the upstream level, for geometrical compliance of the construction - it is a dam crest mark.

  9. Projections for the changes in growing season length of tree-ring formation on the Tibetan Plateau based on CMIP5 model simulations.

    Science.gov (United States)

    He, Minhui; Yang, Bao; Shishov, Vladimir; Rossi, Sergio; Bräuning, Achim; Ljungqvist, Fredrik Charpentier; Grießinger, Jussi

    2018-04-01

    The response of the growing season to the ongoing global warming has gained considerable attention. In particular, how and to which extent the growing season will change during this century is essential information for the Tibetan Plateau, where the observed warming trend has exceeded the global mean. In this study, the 1960-2014 mean length of the tree-ring growing season (LOS) on the Tibetan Plateau was derived from results of the Vaganov-Shashkin oscilloscope tree growth model, based on 20 composite study sites and more than 3000 trees. Bootstrap and partial correlations were used to evaluate the most significant climate factors determining the LOS in the study region. Based on this relationship, we predicted the future variability of the LOS under three emission scenarios (Representative Concentration Pathways (RCP) 2.6, 6.0, and 8.5, representing different concentrations of greenhouse gasses) derived from 17 Earth system models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5). The averaged LOS on the Tibetan Plateau is 103 days during the period 1960-2014, and April-September minimum temperature is the strongest factor controlling the LOS. We detected a general increase in the LOS over the twenty-first century under all the three selected scenarios. By the middle of this century, LOS will extend by about 3 to 4 weeks under the RCPs 2.6 and 6.0, and by more than 1 month (37 days) under the RCP 8.5, relative to the baseline period 1960-2014. From the middle to the end of the twenty-first century, LOS will further extend by about 3 to 4 weeks under the RCPs 6.0 and 8.5, respectively. Under the RCP 2.6 scenario, however, the extension reaches a plateau at around 2050 and about 2 weeks LOS extension. In total, we found an average rate of 2.1, 3.6, and 5.0 days decade -1 for the LOS extension from 2015 to 2100 under the RCPs 2.6, 6.0, and 8.5, respectively. However, such estimated LOS extensions may be offset by other ecological

  10. TRAINING TREE ADJOINING GRAMMARS WITH HUGE TEXT CORPUS USING SPARK MAP REDUCE

    Directory of Open Access Journals (Sweden)

    Vijay Krishna Menon

    2015-07-01

    Full Text Available Tree adjoining grammars (TAGs are mildly context sensitive formalisms used mainly in modelling natural languages. Usage and research on these psycho linguistic formalisms have been erratic in the past decade, due to its demanding construction and difficulty to parse. However, they represent promising future for formalism based NLP in multilingual scenarios. In this paper we demonstrate basic synchronous Tree adjoining grammar for English-Tamil language pair that can be used readily for machine translation. We have also developed a multithreaded chart parser that gives ambiguous deep structures and a par dependency structure known as TAG derivation. Furthermore we then focus on a model for training this TAG for each language using a large corpus of text through a map reduce frequency count model in spark and estimation of various probabilistic parameters for the grammar trees thereafter; these parameters can be used to perform statistical parsing on the trained grammar.

  11. Recruiting Conventional Tree Architecture Models into State-of-the-Art LiDAR Mapping for Investigating Tree Growth Habits in Structure

    Directory of Open Access Journals (Sweden)

    Yi Lin

    2018-02-01

    Full Text Available Mensuration of tree growth habits is of considerable importance for understanding forest ecosystem processes and forest biophysical responses to climate changes. However, the complexity of tree crown morphology that is typically formed after many years of growth tends to render it a non-trivial task, even for the state-of-the-art 3D forest mapping technology—light detection and ranging (LiDAR. Fortunately, botanists have deduced the large structural diversity of tree forms into only a limited number of tree architecture models, which can present a-priori knowledge about tree structure, growth, and other attributes for different species. This study attempted to recruit Hallé architecture models (HAMs into LiDAR mapping to investigate tree growth habits in structure. First, following the HAM-characterized tree structure organization rules, we run the kernel procedure of tree species classification based on the LiDAR-collected point clouds using a support vector machine classifier in the leave-one-out-for-cross-validation mode. Then, the HAM corresponding to each of the classified tree species was identified based on expert knowledge, assisted by the comparison of the LiDAR-derived feature parameters. Next, the tree growth habits in structure for each of the tree species were derived from the determined HAM. In the case of four tree species growing in the boreal environment, the tests indicated that the classification accuracy reached 85.0%, and their growth habits could be derived by qualitative and quantitative means. Overall, the strategy of recruiting conventional HAMs into LiDAR mapping for investigating tree growth habits in structure was validated, thereby paving a new way for efficiently reflecting tree growth habits and projecting forest structure dynamics.

  12. Population differentiation in tree-ring growth response of white fir (Abies concolor) to climate: Implications for predicting forest responses to climate change

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Deborah Bowne [Univ. of California, Berkeley, CA (United States)

    1993-01-01

    Forest succession models and correlative models have predicted 200--650 kilometer shifts in the geographic range of temperate forests and forest species as one response to global climate change. Few studies have investigated whether population differences may effect the response of forest species to climate change. This study examines differences in tree-ring growth, and in the phenotypic plasticity of tree-ring growth in 16-year old white fir, Abies concolor, from ten populations grown in four common gardens in the Sierra Nevada of California. For each population, tree-ring growth was modelled as a function of precipitation and degree-day sums. Tree-ring growth under three scenarios of doubled CO2 climates was estimated.

  13. Assessing the predictive capability of randomized tree-based ensembles in streamflow modelling

    Science.gov (United States)

    Galelli, S.; Castelletti, A.

    2013-07-01

    Combining randomization methods with ensemble prediction is emerging as an effective option to balance accuracy and computational efficiency in data-driven modelling. In this paper, we investigate the prediction capability of extremely randomized trees (Extra-Trees), in terms of accuracy, explanation ability and computational efficiency, in a streamflow modelling exercise. Extra-Trees are a totally randomized tree-based ensemble method that (i) alleviates the poor generalisation property and tendency to overfitting of traditional standalone decision trees (e.g. CART); (ii) is computationally efficient; and, (iii) allows to infer the relative importance of the input variables, which might help in the ex-post physical interpretation of the model. The Extra-Trees potential is analysed on two real-world case studies - Marina catchment (Singapore) and Canning River (Western Australia) - representing two different morphoclimatic contexts. The evaluation is performed against other tree-based methods (CART and M5) and parametric data-driven approaches (ANNs and multiple linear regression). Results show that Extra-Trees perform comparatively well to the best of the benchmarks (i.e. M5) in both the watersheds, while outperforming the other approaches in terms of computational requirement when adopted on large datasets. In addition, the ranking of the input variable provided can be given a physically meaningful interpretation.

  14. Merits of a Scenario Approach in Dredge Plume Modelling

    DEFF Research Database (Denmark)

    Pedersen, Claus; Chu, Amy Ling Chu; Hjelmager Jensen, Jacob

    2011-01-01

    Dredge plume modelling is a key tool for quantification of potential impacts to inform the EIA process. There are, however, significant uncertainties associated with the modelling at the EIA stage when both dredging methodology and schedule are likely to be a guess at best as the dredging...... contractor would rarely have been appointed. Simulation of a few variations of an assumed full dredge period programme will generally not provide a good representation of the overall environmental risks associated with the programme. An alternative dredge plume modelling strategy that attempts to encapsulate...... uncertainties associated with preliminary dredging programmes by using a scenario-based modelling approach is presented. The approach establishes a set of representative and conservative scenarios for key factors controlling the spill and plume dispersion and simulates all combinations of e.g. dredge, climatic...

  15. Models for estimation of tree volume in the miombo woodlands of ...

    African Journals Online (AJOL)

    Volume of trees is an important parameter in forest management, but only volume models with limited geographical and tree size coverage have previously been developed for Tanzanian miombo woodlands. This study developed models for estimating total, merchantable stem and branches volume applicable for the entire ...

  16. Modeling time-to-event (survival) data using classification tree analysis.

    Science.gov (United States)

    Linden, Ariel; Yarnold, Paul R

    2017-12-01

    Time to the occurrence of an event is often studied in health research. Survival analysis differs from other designs in that follow-up times for individuals who do not experience the event by the end of the study (called censored) are accounted for in the analysis. Cox regression is the standard method for analysing censored data, but the assumptions required of these models are easily violated. In this paper, we introduce classification tree analysis (CTA) as a flexible alternative for modelling censored data. Classification tree analysis is a "decision-tree"-like classification model that provides parsimonious, transparent (ie, easy to visually display and interpret) decision rules that maximize predictive accuracy, derives exact P values via permutation tests, and evaluates model cross-generalizability. Using empirical data, we identify all statistically valid, reproducible, longitudinally consistent, and cross-generalizable CTA survival models and then compare their predictive accuracy to estimates derived via Cox regression and an unadjusted naïve model. Model performance is assessed using integrated Brier scores and a comparison between estimated survival curves. The Cox regression model best predicts average incidence of the outcome over time, whereas CTA survival models best predict either relatively high, or low, incidence of the outcome over time. Classification tree analysis survival models offer many advantages over Cox regression, such as explicit maximization of predictive accuracy, parsimony, statistical robustness, and transparency. Therefore, researchers interested in accurate prognoses and clear decision rules should consider developing models using the CTA-survival framework. © 2017 John Wiley & Sons, Ltd.

  17. Transforming Graphical System Models to Graphical Attack Models

    DEFF Research Database (Denmark)

    Ivanova, Marieta Georgieva; Probst, Christian W.; Hansen, Rene Rydhof

    2016-01-01

    Manually identifying possible attacks on an organisation is a complex undertaking; many different factors must be considered, and the resulting attack scenarios can be complex and hard to maintain as the organisation changes. System models provide a systematic representation of organisations...... approach to transforming graphical system models to graphical attack models in the form of attack trees. Based on an asset in the model, our transformations result in an attack tree that represents attacks by all possible actors in the model, after which the actor in question has obtained the asset....

  18. Modelling modulus of elasticity of Pinus pinaster Ait. in northwestern Spain with standing tree acoustic measurements, tree, stand and site variables

    Directory of Open Access Journals (Sweden)

    Esther Merlo

    2014-04-01

    Full Text Available Aim of study: Modelling the structural quality of Pinus pinaster Ait. wood on the basis of measurements made on standing trees is essential because of the importance of the species in the Galician forestry and timber industries and the good mechanical properties of its wood. In this study, we investigated how timber stiffness is affected by tree and stand properties, climatic and edaphic characteristics and competition. Area of study: The study was performed in Galicia, north-western Spain.Material and methods: Ten pure and even-aged P. pinaster stands were selected and tree and stand variables and the stress wave velocity of 410 standing trees were measured. A sub-sample of 73 trees, representing the variability in acoustic velocity, were felled and sawed into structural timber pieces (224 which were subjected to a bending test to determine the modulus of elasticity (MOE. Main results: Linear models including wood properties explained more than 97%, 73% and 60% of the observed MOE variability at site, tree and board level, respectively, with acoustic velocity and wood density as the main regressors. Other linear models, which did not include wood density, explained more than 88%, 69% and 55% of the observed MOE variability at site, tree and board level, respectively, with acoustic velocity as the main regressor. Moreover, a classification tree for estimating the visual grade according to standard UNE 56544:2011 was developed. Research highlights: The results have demonstrated the usefulness of acoustic velocity for predicting MOE in standing trees. The use of the fitted equations together with existing dynamic growth models will enable preliminary assessment of timber stiffness in relation to different silvicultural alternatives used with this species.Keywords: stress wave velocity, modulus of elasticity, site index, competition index, stepwise regression, CART.

  19. Developing Models to Forcast Sales of Natural Christmas Trees

    Science.gov (United States)

    Lawrence D. Garrett; Thomas H. Pendleton

    1977-01-01

    A study of practices for marketing Christmas trees in Winston-Salem, North Carolina, and Denver, Colorado, revealed that such factors as retail lot competition, tree price, consumer traffic, and consumer income were very important in determining a particular retailer's sales. Analyses of 4 years of market data were used in developing regression models for...

  20. Valuating Indonesian upstream oil management scenario through system dynamics modelling

    Science.gov (United States)

    Ketut Gunarta, I.; Putri, F. A.

    2018-04-01

    Under the existing regulation in Constitution Number 22 Year 2001 (UU No 22 Tahun 2001), Production Sharing Contract (PSC) continues to be the scenario in conducting oil and gas upstream mining activities as the previous regulation (UU No. 8 Tahun 1971). Because of the high costs and risks in upstream mining activities, the contractors are dominated by foreign companies, meanwhile National Oil Company (NOC) doesn’t act much. The domination of foreign contractor companies also warned Indonesia in several issues addressing to energy independence and energy security. Therefore, to achieve the goals of energy which is independence and security, there need to be a revision in upstream oil activities regulating scenario. The scenarios will be comparing the current scenario, which is PSC, with the “full concession” scenario for National Oil Company (NOC) in managing oil upstream mining activities. Both scenario will be modelled using System Dynamics methodology and assessed furthermore using financial valuation method of income approach. Under the 2 scenarios, the author will compare which scenario is better for upstream oil management in reaching the goals mentioned before and more profitable in financial aspect. From the simulation, it is gathered that concession scenario offers better option than PSC in reaching energy independence and energy security.

  1. Highly Accurate Tree Models Derived from Terrestrial Laser Scan Data: A Method Description

    Directory of Open Access Journals (Sweden)

    Jan Hackenberg

    2014-05-01

    Full Text Available This paper presents a method for fitting cylinders into a point cloud, derived from a terrestrial laser-scanned tree. Utilizing high scan quality data as the input, the resulting models describe the branching structure of the tree, capable of detecting branches with a diameter smaller than a centimeter. The cylinders are stored as a hierarchical tree-like data structure encapsulating parent-child neighbor relations and incorporating the tree’s direction of growth. This structure enables the efficient extraction of tree components, such as the stem or a single branch. The method was validated both by applying a comparison of the resulting cylinder models with ground truth data and by an analysis between the input point clouds and the models. Tree models were accomplished representing more than 99% of the input point cloud, with an average distance from the cylinder model to the point cloud within sub-millimeter accuracy. After validation, the method was applied to build two allometric models based on 24 tree point clouds as an example of the application. Computation terminated successfully within less than 30 min. For the model predicting the total above ground volume, the coefficient of determination was 0.965, showing the high potential of terrestrial laser-scanning for forest inventories.

  2. Dry forest resilience varies under simulated climate‐management scenarios in a central Oregon, USA landscape.

    Science.gov (United States)

    Halofsky, Joshua S; Halofsky, Jessica E; Burcsu, Theresa; Hemstrom, Miles A

    Determining appropriate actions to create or maintain landscapes resilient to climate change is challenging because of uncertainty associated with potential effects of climate change and their interactions with land management. We used a set of climate-informed state-and-transition models to explore the effects of management and natural disturbances on vegetation composition and structure under different future climates. Models were run for dry forests of central Oregon under a fire suppression scenario (i.e., no management other than the continued suppression of wildfires) and an active management scenario characterized by light to moderate thinning from below and some prescribed fire, planting, and salvage logging. Without climate change, area in dry province forest types remained constant. With climate change, dry mixed-conifer forests increased in area (by an average of 21–26% by 2100), and moist mixed-conifer forests decreased in area (by an average of 36–60% by 2100), under both management scenarios. Average area in dry mixed-conifer forests varied little by management scenario, but potential decreases in the moist mixed-conifer forest were lower with active management. With changing climate in the dry province of central Oregon, our results suggest the likelihood of sustaining current levels of dense, moist mixed-conifer forests with large-diameter, old trees is low (less than a 10% chance) irrespective of management scenario; an opposite trend was observed under no climate change simulations. However, results also suggest active management within the dry and moist mixed-conifer forests that creates less dense forest conditions can increase the persistence of larger-diameter, older trees across the landscape. Owing to projected increases in wildfire, our results also suggest future distributions of tree structures will differ from the present. Overall, our projections indicate proactive management can increase forest resilience and sustain some societal

  3. Modeling the temporal dynamics of nonstructural carbohydrate pools in forest trees

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, Andrew [Northern Arizona Univ., Flagstaff, AZ (United States); Harvard Univ., Cambridge, MA (United States)

    2017-11-09

    Trees store carbohydrates, in the form of sugars and starch, as reserves to be used to power both future growth as well as to support day-to-day metabolic functions. These reserves are particularly important in the context of how trees cope with disturbance and stress—for example, as related to pest outbreaks, wind or ice damage, and extreme climate events. In this project, we measured the size of carbon reserves in forest trees, and determined how quickly these reserves are used and replaced—i.e., their “turnover time”. Our work was conducted at Harvard Forest, a temperate deciduous forest in central Massachusetts. Through field sampling, laboratory-based chemical analyses, and allometric modeling, we scaled these measurements up to whole-tree NSC budgets. We used these data to test and improve computer simulation models of carbon flow through forest ecosystems. Our modeling focused on the mathematical representation of these stored carbon reserves, and we examined the sensitivity of model performance to different model structures. This project contributes to DOE’s goal to improve next-generation models of the earth system, and to understand the impacts of climate change on terrestrial ecosystems.

  4. Above- and Belowground Biomass Models for Trees in the Miombo Woodlands of Malawi

    Directory of Open Access Journals (Sweden)

    Daud J. Kachamba

    2016-02-01

    Full Text Available In this study we present general (multiple tree species from several sites above- and belowground biomass models for trees in the miombo woodlands of Malawi. Such models are currently lacking in the country. The modelling was based on 74 trees comprising 33 different species with diameters at breast height (dbh and total tree height (ht ranging from 5.3 to 2 cm and from 3.0 to 25.0 m, respectively. Trees were collected from four silvicultural zones covering a wide range of conditions. We tested different models including dbh, ht and wood specific gravity ( ρ as independent variables. We evaluated model performance using pseudo-R2, root mean square error (RMSE, a covariance matrix for the parameter estimates, mean prediction error (MPE and relative mean prediction error (MPE%. Computation of MPE% was based on leave-one-out cross-validation. Values of pseudo-R2 and MPE% ranged 0.82–0.97 and 0.9%–2.8%, respectively. Model performance indicated that the models can be used over a wide range of geographical and ecological conditions in Malawi.

  5. Climate change and socio-economic scenarios, land use modelling implications on water resources in an inner alpine area, Switzerland

    Science.gov (United States)

    Rey, Emmanuel; Schneider, Flurina; Liniger, Hanspeter; Weingartner, Rolf; Herweg, Karl

    2014-05-01

    The MontanAqua project aims to study the water resources management in the region Sierre-Montana (Valais, Switzerland). Land use is known to have an influence on the water resources (soil moisture dynamic, soil sealing, surface runoff and deep percolation). Thus land use modelling is of importance for the water resources management. An actual land use map was produced using infrared imagery (Niklaus 2012, Fig.1). Land use changes are known to be mainly drived by socio-economic factors as well as climatic factors (Dolman et al. 2003). Potential future Land uses was separatly predicted according to 1-. socio-economic and 2-. climatic/abiotic drivers : 1. 4 socio-economic scenarios were developped with stakeholders (Schneider et al. 2013) between 2010 and 2012. We modeled those socio-economic scenarios into a GIS application using Python programming (ModelBuilder in ArcGIS 10) to get a cartographic transcription of the wishes of the stakeholders for their region in 2050. 2. Uncorrelated climatic and abiotic drivers were used in a BIOMOD2 (Georges et al. 2013) framework. 4 models were used: Maximum Entropy (MAXENT), Multiple Adaptive Regression Splines (MARS), Classification Tree Analysis (CTA) and the Flexible Discriminant Analysis (FDA) to predict grassland, alpine pasture, vineyards and forest in our study region. Climatic scenarios were then introduced into the models to predict potential land use in 2050 driven only by climatic and abiotic factors The comparison of all the outputs demonstrates that the socio-economic drivers will have a more important impact in the region than the climatic drivers (e.g. -70% grassland surface for the worst socio-economic scenario vs. -40% of grassland surface for the worst climatic models). Further analysis also brings out the sensitivity of the grassland/alpine pasture system to the climate change and to socio-economic changes. Future work will be to cross the different land use maps obtained by the two model types and to use

  6. Nervous systems and scenarios for the invertebrate-to-vertebrate transition.

    Science.gov (United States)

    Holland, Nicholas D

    2016-01-05

    Older evolutionary scenarios for the origin of vertebrates often gave nervous systems top billing in accordance with the notion that a big-brained Homo sapiens crowned a tree of life shaped mainly by progressive evolution. Now, however, tree thinking positions all extant organisms equidistant from the tree's root, and molecular phylogenies indicate that regressive evolution is more common than previously suspected. Even so, contemporary theories of vertebrate origin still focus on the nervous system because of its functional importance, its richness in characters for comparative biology, and its central position in the two currently prominent scenarios for the invertebrate-to-vertebrate transition, which grew out of the markedly neurocentric annelid and enteropneust theories of the nineteenth century. Both these scenarios compare phyla with diverse overall body plans. This diversity, exacerbated by the scarcity of relevant fossil data, makes it challenging to establish plausible homologies between component parts (e.g. nervous system regions). In addition, our current understanding of the relation between genotype and phenotype is too preliminary to permit us to convert gene network data into structural features in any simple way. These issues are discussed here with special reference to the evolution of nervous systems during proposed transitions from invertebrates to vertebrates. © 2015 The Author(s).

  7. Systems analysis approach to probabilistic modeling of fault trees

    International Nuclear Information System (INIS)

    Bartholomew, R.J.; Qualls, C.R.

    1985-01-01

    A method of probabilistic modeling of fault tree logic combined with stochastic process theory (Markov modeling) has been developed. Systems are then quantitatively analyzed probabilistically in terms of their failure mechanisms including common cause/common mode effects and time dependent failure and/or repair rate effects that include synergistic and propagational mechanisms. The modeling procedure results in a state vector set of first order, linear, inhomogeneous, differential equations describing the time dependent probabilities of failure described by the fault tree. The solutions of this Failure Mode State Variable (FMSV) model are cumulative probability distribution functions of the system. A method of appropriate synthesis of subsystems to form larger systems is developed and applied to practical nuclear power safety systems

  8. Biophysical modelling of intra-ring variations in tracheid features and wood density of Pinus pinaster trees exposed to seasonal droughts.

    Science.gov (United States)

    Wilkinson, Sarah; Ogée, Jérôme; Domec, Jean-Christophe; Rayment, Mark; Wingate, Lisa

    2015-03-01

    Process-based models that link seasonally varying environmental signals to morphological features within tree rings are essential tools to predict tree growth response and commercially important wood quality traits under future climate scenarios. This study evaluated model portrayal of radial growth and wood anatomy observations within a mature maritime pine (Pinus pinaster (L.) Aït.) stand exposed to seasonal droughts. Intra-annual variations in tracheid anatomy and wood density were identified through image analysis and X-ray densitometry on stem cores covering the growth period 1999-2010. A cambial growth model was integrated with modelled plant water status and sugar availability from the soil-plant-atmosphere transfer model MuSICA to generate estimates of cell number, cell volume, cell mass and wood density on a weekly time step. The model successfully predicted inter-annual variations in cell number, ring width and maximum wood density. The model was also able to predict the occurrence of special anatomical features such as intra-annual density fluctuations (IADFs) in growth rings. Since cell wall thickness remained surprisingly constant within and between growth rings, variations in wood density were primarily the result of variations in lumen diameter, both in the model and anatomical data. In the model, changes in plant water status were identified as the main driver of the IADFs through a direct effect on cell volume. The anatomy data also revealed that a trade-off existed between hydraulic safety and hydraulic efficiency. Although a simplified description of cambial physiology is presented, this integrated modelling approach shows potential value for identifying universal patterns of tree-ring growth and anatomical features over a broad climatic gradient. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  9. From Modelling to Execution of Enterprise Integration Scenarios: The GENIUS Tool

    Science.gov (United States)

    Scheibler, Thorsten; Leymann, Frank

    One of the predominant problems IT companies are facing today is Enterprise Application Integration (EAI). Most of the infrastructures built to tackle integration issues are proprietary because no standards exist for how to model, develop, and actually execute integration scenarios. EAI patterns gain importance for non-technical business users to ease and harmonize the development of EAI scenarios. These patterns describe recurring EAI challenges and propose possible solutions in an abstract way. Therefore, one can use those patterns to describe enterprise architectures in a technology neutral manner. However, patterns are documentation only used by developers and systems architects to decide how to implement an integration scenario manually. Thus, patterns are not theoretical thought to stand for artefacts that will immediately be executed. This paper presents a tool supporting a method how EAI patterns can be used to generate executable artefacts for various target platforms automatically using a model-driven development approach, hence turning patterns into something executable. Therefore, we introduce a continuous tool chain beginning at the design phase and ending in executing an integration solution in a completely automatically manner. For evaluation purposes we introduce a scenario demonstrating how the tool is utilized for modelling and actually executing an integration scenario.

  10. Yield curve event tree construction for multi stage stochastic programming models

    DEFF Research Database (Denmark)

    Rasmussen, Kourosh Marjani; Poulsen, Rolf

    Dynamic stochastic programming (DSP) provides an intuitive framework for modelling of financial portfolio choice problems where market frictions are present and dynamic re--balancing has a significant effect on initial decisions. The application of these models in practice, however, is limited....... Indeed defining a universal and tractable framework for fully ``appropriate'' event trees is in our opinion an impossible task. A problem specific approach to designing such event trees is the way ahead. In this paper we propose a number of desirable properties which should be present in an event tree...

  11. Tree-Structured Digital Organisms Model

    Science.gov (United States)

    Suzuki, Teruhiko; Nobesawa, Shiho; Tahara, Ikuo

    Tierra and Avida are well-known models of digital organisms. They describe a life process as a sequence of computation codes. A linear sequence model may not be the only way to describe a digital organism, though it is very simple for a computer-based model. Thus we propose a new digital organism model based on a tree structure, which is rather similar to the generic programming. With our model, a life process is a combination of various functions, as if life in the real world is. This implies that our model can easily describe the hierarchical structure of life, and it can simulate evolutionary computation through mutual interaction of functions. We verified our model by simulations that our model can be regarded as a digital organism model according to its definitions. Our model even succeeded in creating species such as viruses and parasites.

  12. GEOMETRIC MODELLING OF TREE ROOTS WITH DIFFERENT LEVELS OF DETAIL

    Directory of Open Access Journals (Sweden)

    J. I. Guerrero Iñiguez

    2017-09-01

    Full Text Available This paper presents a geometric approach for modelling tree roots with different Levels of Detail, suitable for analysis of the tree anchoring, potentially occupied underground space, interaction with urban elements and damage produced and taken in the built-in environment. Three types of tree roots are considered to cover several species: tap root, heart shaped root and lateral roots. Shrubs and smaller plants are not considered, however, a similar approach can be considered if the information is available for individual species. The geometrical approach considers the difficulties of modelling the actual roots, which are dynamic and almost opaque to direct observation, proposing generalized versions. For each type of root, different geometric models are considered to capture the overall shape of the root, a simplified block model, and a planar or surface projected version. Lower detail versions are considered as compatibility version for 2D systems while higher detail models are suitable for 3D analysis and visualization. The proposed levels of detail are matched with CityGML Levels of Detail, enabling both analysis and aesthetic views for urban modelling.

  13. Geometric Modelling of Tree Roots with Different Levels of Detail

    Science.gov (United States)

    Guerrero Iñiguez, J. I.

    2017-09-01

    This paper presents a geometric approach for modelling tree roots with different Levels of Detail, suitable for analysis of the tree anchoring, potentially occupied underground space, interaction with urban elements and damage produced and taken in the built-in environment. Three types of tree roots are considered to cover several species: tap root, heart shaped root and lateral roots. Shrubs and smaller plants are not considered, however, a similar approach can be considered if the information is available for individual species. The geometrical approach considers the difficulties of modelling the actual roots, which are dynamic and almost opaque to direct observation, proposing generalized versions. For each type of root, different geometric models are considered to capture the overall shape of the root, a simplified block model, and a planar or surface projected version. Lower detail versions are considered as compatibility version for 2D systems while higher detail models are suitable for 3D analysis and visualization. The proposed levels of detail are matched with CityGML Levels of Detail, enabling both analysis and aesthetic views for urban modelling.

  14. Comparing tree foliage biomass models fitted to a multispecies, felled-tree biomass dataset for the United States

    Science.gov (United States)

    Brian J. Clough; Matthew B. Russell; Grant M. Domke; Christopher W. Woodall; Philip J. Radtke

    2016-01-01

    tEstimation of live tree biomass is an important task for both forest carbon accounting and studies of nutri-ent dynamics in forest ecosystems. In this study, we took advantage of an extensive felled-tree database(with 2885 foliage biomass observations) to compare different models and grouping schemes based onphylogenetic and geographic variation for predicting foliage...

  15. Harvesting cost model for small trees in natural stands in the interior northwest.

    Science.gov (United States)

    Bruce R. Hartsough; Xiaoshan Zhang; Roger D. Fight

    2001-01-01

    Realistic logging cost models are needed for long-term forest management planning. Data from numerous published studies were combined to estimate the costs of harvesting small trees in natural stands in the Interior Northwest of North America. Six harvesting systems were modeled. Four address gentle terrain: manual log-length, manual whole-tree, mechanized whole-tree,...

  16. Adaptive scenarios: a training model for today's public health workforce.

    Science.gov (United States)

    Uden-Holman, Tanya; Bedet, Jennifer; Walkner, Laurie; Abd-Hamid, Nor Hashidah

    2014-01-01

    With the current economic climate, money for training is scarce. In addition, time is a major barrier to participation in trainings. To meet the public health workforce's rising demand for training, while struggling with less time and fewer resources, the Upper Midwest Preparedness and Emergency Response Learning Center has developed a model of online training that provides the public health workforce with individually customized, needs-based training experiences. Adaptive scenarios are rooted in case-based reasoning, a learning approach that focuses on the specific knowledge needed to solve a problem. Proponents of case-based reasoning argue that learners benefit from being able to remember previous similar situations and reusing information and knowledge from that situation. Adaptive scenarios based on true-to-life job performance provide an opportunity to assess skills by presenting the user with choices to make in a problem-solving context. A team approach was used to develop the adaptive scenarios. Storylines were developed that incorporated situations aligning with the knowledge, skills, and attitudes outlined in the Public Health Preparedness and Response Core Competency Model. This article examines 2 adaptive scenarios: "Ready or Not? A Family Preparedness Scenario" and "Responding to a Crisis: Managing Emotions and Stress Scenario." The scenarios are available on Upper Midwest Preparedness and Emergency Response Learning Center's Learning Management System, the Training Source (http://training-source.org). Evaluation data indicate that users' experiences have been positive. Integrating the assessment and training elements of the scenarios so that the training experience is uniquely adaptive to each user is one of the most efficient ways to provide training. The opportunity to provide individualized, needs-based training without having to administer separate assessments has the potential to save time and resources. These adaptive scenarios continue to be

  17. TERNIRBU: Description of model and individual evaluation of model performance for scenario S

    International Nuclear Information System (INIS)

    Kanyar, B.; Fueloep, N.

    1996-01-01

    The compartmental model used is realized as a procedure of the general purpose code TAMDYN for simulation, sensitivity and uncertainty calculations of dynamic models. More details of the model structure and parameters are given in the description of the VAMP MP Scenario CB. The difference between the climate in Finland and Central Bohemia was taken into consideration by shifting the seasonality function with 12 days' according to the weekly average temperature. The lake system and the contamination of fishes was simulated by the model SIRATEC used and validated in the BIOMOVS Scenario A5. The model was extended to two fish-compartments for roach and pike ones as a catanary system. For simulations the code TAMDYN was used. The doses were estimated from the time integrated concentrations of the proper components multiplied by the dose conversion factor. 4 figs

  18. A modeling study of the impact of urban trees on ozone

    Science.gov (United States)

    David J. Nowak; Kevin L. Civerolo; S. Trivikrama Rao; Gopal Sistla; Christopher J. Luley; Daniel E. Crane

    2000-01-01

    Modeling the effects of increased urban tree cover on ozone concentrations (July 13-15, 1995) from Washington, DC, to central Massachusetts reveals that urban trees generally reduce ozone concentrations in cities, but tend to increase average ozone concentrations in the overall modeling domain. During the daytime, average ozone reductions in urban areas (1 ppb) were...

  19. Mapping potential carbon and timber losses from hurricanes using a decision tree and ecosystem services driver model.

    Science.gov (United States)

    Delphin, S; Escobedo, F J; Abd-Elrahman, A; Cropper, W

    2013-11-15

    Information on the effect of direct drivers such as hurricanes on ecosystem services is relevant to landowners and policy makers due to predicted effects from climate change. We identified forest damage risk zones due to hurricanes and estimated the potential loss of 2 key ecosystem services: aboveground carbon storage and timber volume. Using land cover, plot-level forest inventory data, the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model, and a decision tree-based framework; we determined potential damage to subtropical forests from hurricanes in the Lower Suwannee River (LS) and Pensacola Bay (PB) watersheds in Florida, US. We used biophysical factors identified in previous studies as being influential in forest damage in our decision tree and hurricane wind risk maps. Results show that 31% and 0.5% of the total aboveground carbon storage in the LS and PB, respectively was located in high forest damage risk (HR) zones. Overall 15% and 0.7% of the total timber net volume in the LS and PB, respectively, was in HR zones. This model can also be used for identifying timber salvage areas, developing ecosystem service provision and management scenarios, and assessing the effect of other drivers on ecosystem services and goods. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Estimating Coextinction Risks from Epidemic Tree Death: Affiliate Lichen Communities among Diseased Host Tree Populations of Fraxinus excelsior

    Science.gov (United States)

    Jönsson, Mari T.; Thor, Göran

    2012-01-01

    At least 10% of the world’s tree species are threatened with extinction and pathogens are increasingly implicated in tree threats. Coextinction and threats to affiliates as a consequence of the loss or decline of their host trees is a poorly understood phenomenon. Ash dieback is an emerging infectious disease causing severe dieback of common ash Fraxinus excelsior throughout Europe. We utilized available empirical data on affiliate epiphytic lichen diversity (174 species and 17,800 observations) among 20 ash dieback infected host tree populations of F. excelsior on the island Gotland in the Baltic Sea, Sweden. From this, we used structured scenario projections scaled with empirical data of ash dieback disease to generate probabilistic models for estimating local and regional lichen coextinction risks. Average coextinction probabilities (Ā) were 0.38 (95% CI ±0.09) for lichens occurring on F. excelsior and 0.14 (95% CI ±0.03) when considering lichen persistence on all tree species. Ā was strongly linked to local disease incidence levels and generally increasing with lichen host specificity to F. excelsior and decreasing population size. Coextinctions reduced affiliate community viability, with significant local reductions in species richness and shifts in lichen species composition. Affiliates were projected to become locally extirpated before their hosts, illuminating the need to also consider host tree declines. Traditionally managed open wooded meadows had the highest incidence of ash dieback disease and significantly higher proportions of affiliate species projected to go extinct, compared with unmanaged closed forests and semi-open grazed sites. Most cothreatened species were not previously red-listed, which suggest that tree epidemics cause many unforeseen threats to species. Our analysis shows that epidemic tree deaths represent an insidious, mostly overlooked, threat to sessile affiliate communities in forested environments. Current conservation and

  1. Runtime Optimizations for Tree-Based Machine Learning Models

    NARCIS (Netherlands)

    N. Asadi; J.J.P. Lin (Jimmy); A.P. de Vries (Arjen)

    2014-01-01

    htmlabstractTree-based models have proven to be an effective solution for web ranking as well as other machine learning problems in diverse domains. This paper focuses on optimizing the runtime performance of applying such models to make predictions, specifically using gradient-boosted regression

  2. Modelling of electric tree progression due to space charge modified fields

    International Nuclear Information System (INIS)

    Seralathan, K E; Mahajan, A; Gupta, Nandini

    2008-01-01

    Tree initiation and growth require localized field enhancement that results in material erosion and formation of tree channels. Tree progression is linked to partial discharges within the tree tubules, characterized by recurrent periods of activity followed by quiescent states. Charge builds up across the non-conducting tree channels during the inactive regime, and discharge follows. In this work, the role of the space charge modified field during the non-discharging regime in deciding the site of subsequent discharges and thereby shaping tree structures is studied. A simple stochastic model was developed, in order to understand the respective effects of charges trapped on the walls of tree tubules, at channel tips, or in the volume of the dielectric. While some charge distributions are seen to arrest tree growth, others encourage axial growth towards the other electrode, and some aid in producing bushy trees clustered around the needle tip. The effect of carbon deposition within tree channels, making them effectively conducting, was also investigated. The insights gained from the simulations were successfully used to explain tree growth in the laboratory under high- and low-field conditions

  3. Scenario planning.

    Science.gov (United States)

    Enzmann, Dieter R; Beauchamp, Norman J; Norbash, Alexander

    2011-03-01

    In facing future developments in health care, scenario planning offers a complementary approach to traditional strategic planning. Whereas traditional strategic planning typically consists of predicting the future at a single point on a chosen time horizon and mapping the preferred plans to address such a future, scenario planning creates stories about multiple likely potential futures on a given time horizon and maps the preferred plans to address the multiple described potential futures. Each scenario is purposefully different and specifically not a consensus worst-case, average, or best-case forecast; nor is scenario planning a process in probabilistic prediction. Scenario planning focuses on high-impact, uncertain driving forces that in the authors' example affect the field of radiology. Uncertainty is the key concept as these forces are mapped onto axes of uncertainty, the poles of which have opposed effects on radiology. One chosen axis was "market focus," with poles of centralized health care (government control) vs a decentralized private market. Another axis was "radiology's business model," with one pole being a unified, single specialty vs a splintered, disaggregated subspecialty. The third axis was "technology and science," with one pole representing technology enabling to radiology vs technology threatening to radiology. Selected poles of these axes were then combined to create 3 scenarios. One scenario, termed "entrepreneurialism," consisted of a decentralized private market, a disaggregated business model, and threatening technology and science. A second scenario, termed "socialized medicine," had a centralized market focus, a unified specialty business model, and enabling technology and science. A third scenario, termed "freefall," had a centralized market focus, a disaggregated business model, and threatening technology and science. These scenarios provide a range of futures that ultimately allow the identification of defined "signposts" that can

  4. Documentation and evaluation of model validation data used in scenario S

    International Nuclear Information System (INIS)

    Rantavaara, A.; Arvela, H.; Suomela, M.

    1996-01-01

    Most radioactive fallout received in Finland after the Chernobyl nuclear accident originated in the first major release and spread over the test region between April 27 and 29, 1986. Most radioactive material was deposited with heavy showers which caused an uneven areal distribution. Deposition continued with varying intensity until May 12. At the end of April the growing season had not yet begun in Finland. Estimation of the mean deposition density was one of the modelling tasks. To avoid a biased starting point for foodchain assessments due to modellers' own deposition estimates, the mean deposition density of 137 Cs in each subregion used in the scenario was given as input information. The model validation test was started as a blind test. All regional information in the scenario description was coded, and the first maps of subregions were schematic to hide the actual test area. The blind test idea was gradually cancelled in the course of the exercise. The geographical region S was revealed after deposition estimates were made. At the same time, sources of information in the open literature became available to the modellers. After the blind test phase, communication was encouraged between modellers and the compiler of the scenario description at the Finnish Centre for Radiation and Nuclear Safety (STUK) to avoid unnecessary misinterpretations of input information. Clarifications and additional information provided in the course of model calculations are included in the present scenario description. 100 refs, 31 figs, 67 tabs

  5. The future of large old trees in urban landscapes.

    Science.gov (United States)

    Le Roux, Darren S; Ikin, Karen; Lindenmayer, David B; Manning, Adrian D; Gibbons, Philip

    2014-01-01

    Large old trees are disproportionate providers of structural elements (e.g. hollows, coarse woody debris), which are crucial habitat resources for many species. The decline of large old trees in modified landscapes is of global conservation concern. Once large old trees are removed, they are difficult to replace in the short term due to typically prolonged time periods needed for trees to mature (i.e. centuries). Few studies have investigated the decline of large old trees in urban landscapes. Using a simulation model, we predicted the future availability of native hollow-bearing trees (a surrogate for large old trees) in an expanding city in southeastern Australia. In urban greenspace, we predicted that the number of hollow-bearing trees is likely to decline by 87% over 300 years under existing management practices. Under a worst case scenario, hollow-bearing trees may be completely lost within 115 years. Conversely, we predicted that the number of hollow-bearing trees will likely remain stable in semi-natural nature reserves. Sensitivity analysis revealed that the number of hollow-bearing trees perpetuated in urban greenspace over the long term is most sensitive to the: (1) maximum standing life of trees; (2) number of regenerating seedlings ha(-1); and (3) rate of hollow formation. We tested the efficacy of alternative urban management strategies and found that the only way to arrest the decline of large old trees requires a collective management strategy that ensures: (1) trees remain standing for at least 40% longer than currently tolerated lifespans; (2) the number of seedlings established is increased by at least 60%; and (3) the formation of habitat structures provided by large old trees is accelerated by at least 30% (e.g. artificial structures) to compensate for short term deficits in habitat resources. Immediate implementation of these recommendations is needed to avert long term risk to urban biodiversity.

  6. Overview of the Biomass Scenario Model

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, Steve [Lexidyne, LLC, Colorado Springs, CO (United States)

    2015-09-01

    This report describes the structure of the October 2012 version of the Biomass Scenario Model (BSM) in considerable detail, oriented towards readers with a background or interest in the underlying modeling structures. Readers seeking a less-detailed summary of the BSM may refer to Peterson (2013). BSM aims to provide a framework for exploring the potential contribution of biofuel technologies to the transportation energy supply for the United States over the next several decades. The model has evolved significantly from the prototype developed as part of the Role of Biomass in America" tm s Energy Future (RBAEF) project. BSM represents the supply chain surrounding conversion pathways for multiple fuel products, including ethanol, butanol, and infrastructure-compatible biofuels such as diesel, jet fuel, and gasoline.

  7. Simple Prediction of Type 2 Diabetes Mellitus via Decision Tree Modeling

    Directory of Open Access Journals (Sweden)

    Mehrab Sayadi

    2017-06-01

    Full Text Available Background: Type 2 Diabetes Mellitus (T2DM is one of the most important risk factors in cardiovascular disorders considered as a common clinical and public health problem. Early diagnosis can reduce the burden of the disease. Decision tree, as an advanced data mining method, can be used as a reliable tool to predict T2DM. Objectives: This study aimed to present a simple model for predicting T2DM using decision tree modeling. Materials and Methods: This analytical model-based study used a part of the cohort data obtained from a database in Healthy Heart House of Shiraz, Iran. The data included routine information, such as age, gender, Body Mass Index (BMI, family history of diabetes, and systolic and diastolic blood pressure, which were obtained from the individuals referred for gathering baseline data in Shiraz cohort study from 2014 to 2015. Diabetes diagnosis was used as binary datum. Decision tree technique and J48 algorithm were applied using the WEKA software (version 3.7.5, New Zealand. Additionally, Receiver Operator Characteristic (ROC curve and Area Under Curve (AUC were used for checking the goodness of fit. Results: The age of the 11302 cases obtained after data preparation ranged from 18 to 89 years with the mean age of 48.1 ± 11.4 years. Additionally, 51.1% of the cases were male. In the tree structure, blood pressure and age were placed where most information was gained. In our model, however, gender was not important and was placed on the final branch of the tree. Total precision and AUC were 87% and 89%, respectively. This indicated that the model had good accuracy for distinguishing patients from normal individuals. Conclusions: The results showed that T2DM could be predicted via decision tree model without laboratory tests. Thus, this model can be used in pre-clinical and public health screening programs.

  8. An Objective Approach to Select Climate Scenarios when Projecting Species Distribution under Climate Change.

    Directory of Open Access Journals (Sweden)

    Nicolas Casajus

    Full Text Available An impressive number of new climate change scenarios have recently become available to assess the ecological impacts of climate change. Among these impacts, shifts in species range analyzed with species distribution models are the most widely studied. Whereas it is widely recognized that the uncertainty in future climatic conditions must be taken into account in impact studies, many assessments of species range shifts still rely on just a few climate change scenarios, often selected arbitrarily. We describe a method to select objectively a subset of climate change scenarios among a large ensemble of available ones. Our k-means clustering approach reduces the number of climate change scenarios needed to project species distributions, while retaining the coverage of uncertainty in future climate conditions. We first show, for three biologically-relevant climatic variables, that a reduced number of six climate change scenarios generates average climatic conditions very close to those obtained from a set of 27 scenarios available before reduction. A case study on potential gains and losses of habitat by three northeastern American tree species shows that potential future species distributions projected from the selected six climate change scenarios are very similar to those obtained from the full set of 27, although with some spatial discrepancies at the edges of species distributions. In contrast, projections based on just a few climate models vary strongly according to the initial choice of climate models. We give clear guidance on how to reduce the number of climate change scenarios while retaining the central tendencies and coverage of uncertainty in future climatic conditions. This should be particularly useful during future climate change impact studies as more than twice as many climate models were reported in the fifth assessment report of IPCC compared to the previous one.

  9. An Objective Approach to Select Climate Scenarios when Projecting Species Distribution under Climate Change.

    Science.gov (United States)

    Casajus, Nicolas; Périé, Catherine; Logan, Travis; Lambert, Marie-Claude; de Blois, Sylvie; Berteaux, Dominique

    2016-01-01

    An impressive number of new climate change scenarios have recently become available to assess the ecological impacts of climate change. Among these impacts, shifts in species range analyzed with species distribution models are the most widely studied. Whereas it is widely recognized that the uncertainty in future climatic conditions must be taken into account in impact studies, many assessments of species range shifts still rely on just a few climate change scenarios, often selected arbitrarily. We describe a method to select objectively a subset of climate change scenarios among a large ensemble of available ones. Our k-means clustering approach reduces the number of climate change scenarios needed to project species distributions, while retaining the coverage of uncertainty in future climate conditions. We first show, for three biologically-relevant climatic variables, that a reduced number of six climate change scenarios generates average climatic conditions very close to those obtained from a set of 27 scenarios available before reduction. A case study on potential gains and losses of habitat by three northeastern American tree species shows that potential future species distributions projected from the selected six climate change scenarios are very similar to those obtained from the full set of 27, although with some spatial discrepancies at the edges of species distributions. In contrast, projections based on just a few climate models vary strongly according to the initial choice of climate models. We give clear guidance on how to reduce the number of climate change scenarios while retaining the central tendencies and coverage of uncertainty in future climatic conditions. This should be particularly useful during future climate change impact studies as more than twice as many climate models were reported in the fifth assessment report of IPCC compared to the previous one.

  10. Generic physical protection logic trees

    International Nuclear Information System (INIS)

    Paulus, W.K.

    1981-10-01

    Generic physical protection logic trees, designed for application to nuclear facilities and materials, are presented together with a method of qualitative evaluation of the trees for design and analysis of physical protection systems. One or more defense zones are defined where adversaries interact with the physical protection system. Logic trees that are needed to describe the possible scenarios within a defense zone are selected. Elements of a postulated or existing physical protection system are tagged to the primary events of the logic tree. The likelihood of adversary success in overcoming these elements is evaluated on a binary, yes/no basis. The effect of these evaluations is propagated through the logic of each tree to determine whether the adversary is likely to accomplish the end event of the tree. The physical protection system must be highly likely to overcome the adversary before he accomplishes his objective. The evaluation must be conducted for all significant states of the site. Deficiencies uncovered become inputs to redesign and further analysis, closing the loop on the design/analysis cycle

  11. Generic physical protection logic trees

    Energy Technology Data Exchange (ETDEWEB)

    Paulus, W.K.

    1981-10-01

    Generic physical protection logic trees, designed for application to nuclear facilities and materials, are presented together with a method of qualitative evaluation of the trees for design and analysis of physical protection systems. One or more defense zones are defined where adversaries interact with the physical protection system. Logic trees that are needed to describe the possible scenarios within a defense zone are selected. Elements of a postulated or existing physical protection system are tagged to the primary events of the logic tree. The likelihood of adversary success in overcoming these elements is evaluated on a binary, yes/no basis. The effect of these evaluations is propagated through the logic of each tree to determine whether the adversary is likely to accomplish the end event of the tree. The physical protection system must be highly likely to overcome the adversary before he accomplishes his objective. The evaluation must be conducted for all significant states of the site. Deficiencies uncovered become inputs to redesign and further analysis, closing the loop on the design/analysis cycle.

  12. Technology versus demand regulation - strategic modelling of transport, land use and energy scenarios

    International Nuclear Information System (INIS)

    Pfaffenbichler, Paul C.; Shepherd, Simon

    2007-01-01

    Scarcity of oil supply is seen as one of the biggest future threats to our society. The recently finished EU-funded research project STEPs (Scenarios for the Transport System and Energy Supply and their Potential Effects) had the objective to develop, compare and assess possible scenarios for the transport system and the energy supply of the future taking into account the effects on the environment as well as economic and social viability. Two energy supply scenarios, one with and one without scarcity of oil supply, form the basis of STEPs. Furthermore two different policies are suggested to tackle the problem of scarcity of oil: a technology driven strategy and a demand regulation based strategy. This paper presents the application of these scenarios and strategies to the strategic Systems Dynamics model MARS (Metropolitan Activity Relocation Simulator) covering the metropolitan area of Edinburgh. Scenario indicators like car ownership, fleet composition and fuel resource costs were provided by the European model ASTRA and the world energy market model POLES. The first part of the paper summarises the scenarios and strategies in detail. The second part describes briefly some basics of Systems Dynamics as well as the main mechanisms underlying the model MARS. Finally the results of the scenario simulations are presented. The main outcome is that a demand regulation policy is more effective in reducing the consumption of non-renewable energy resources than a technology driven policy

  13. Synchronization scenarios in the Winfree model of coupled oscillators

    Science.gov (United States)

    Gallego, Rafael; Montbrió, Ernest; Pazó, Diego

    2017-10-01

    Fifty years ago Arthur Winfree proposed a deeply influential mean-field model for the collective synchronization of large populations of phase oscillators. Here we provide a detailed analysis of the model for some special, analytically tractable cases. Adopting the thermodynamic limit, we derive an ordinary differential equation that exactly describes the temporal evolution of the macroscopic variables in the Ott-Antonsen invariant manifold. The low-dimensional model is then thoroughly investigated for a variety of pulse types and sinusoidal phase response curves (PRCs). Two structurally different synchronization scenarios are found, which are linked via the mutation of a Bogdanov-Takens point. From our results, we infer a general rule of thumb relating pulse shape and PRC offset with each scenario. Finally, we compare the exact synchronization threshold with the prediction of the averaging approximation given by the Kuramoto-Sakaguchi model. At the leading order, the discrepancy appears to behave as an odd function of the PRC offset.

  14. Detecting treatment-subgroup interactions in clustered data with generalized linear mixed-effects model trees.

    Science.gov (United States)

    Fokkema, M; Smits, N; Zeileis, A; Hothorn, T; Kelderman, H

    2017-10-25

    Identification of subgroups of patients for whom treatment A is more effective than treatment B, and vice versa, is of key importance to the development of personalized medicine. Tree-based algorithms are helpful tools for the detection of such interactions, but none of the available algorithms allow for taking into account clustered or nested dataset structures, which are particularly common in psychological research. Therefore, we propose the generalized linear mixed-effects model tree (GLMM tree) algorithm, which allows for the detection of treatment-subgroup interactions, while accounting for the clustered structure of a dataset. The algorithm uses model-based recursive partitioning to detect treatment-subgroup interactions, and a GLMM to estimate the random-effects parameters. In a simulation study, GLMM trees show higher accuracy in recovering treatment-subgroup interactions, higher predictive accuracy, and lower type II error rates than linear-model-based recursive partitioning and mixed-effects regression trees. Also, GLMM trees show somewhat higher predictive accuracy than linear mixed-effects models with pre-specified interaction effects, on average. We illustrate the application of GLMM trees on an individual patient-level data meta-analysis on treatments for depression. We conclude that GLMM trees are a promising exploratory tool for the detection of treatment-subgroup interactions in clustered datasets.

  15. Modelling Project Feasibility Robustness by Use of Scenarios

    DEFF Research Database (Denmark)

    Moshøj, Claus Rehfeld; Leleur, Steen

    1998-01-01

    , SEAM secures a consistent inclusion of actual scenario elements in the quantitative impact modelling and facilitates a transparent project feasibility robustness analysis. SEAM is implemented as part of a decision support system with a toolbox structure applicable to different types of transport...

  16. Scenario-Led Habitat Modelling of Land Use Change Impacts on Key Species.

    Directory of Open Access Journals (Sweden)

    Matthew Geary

    Full Text Available Accurate predictions of the impacts of future land use change on species of conservation concern can help to inform policy-makers and improve conservation measures. If predictions are spatially explicit, predicted consequences of likely land use changes could be accessible to land managers at a scale relevant to their working landscape. We introduce a method, based on open source software, which integrates habitat suitability modelling with scenario-building, and illustrate its use by investigating the effects of alternative land use change scenarios on landscape suitability for black grouse Tetrao tetrix. Expert opinion was used to construct five near-future (twenty years scenarios for the 800 km2 study site in upland Scotland. For each scenario, the cover of different land use types was altered by 5-30% from 20 random starting locations and changes in habitat suitability assessed by projecting a MaxEnt suitability model onto each simulated landscape. A scenario converting grazed land to moorland and open forestry was the most beneficial for black grouse, and 'increased grazing' (the opposite conversion the most detrimental. Positioning of new landscape blocks was shown to be important in some situations. Increasing the area of open-canopy forestry caused a proportional decrease in suitability, but suitability gains for the 'reduced grazing' scenario were nonlinear. 'Scenario-led' landscape simulation models can be applied in assessments of the impacts of land use change both on individual species and also on diversity and community measures, or ecosystem services. A next step would be to include landscape configuration more explicitly in the simulation models, both to make them more realistic, and to examine the effects of habitat placement more thoroughly. In this example, the recommended policy would be incentives on grazing reduction to benefit black grouse.

  17. Assessing models of speciation under different biogeographic scenarios; An empirical study using multi-locus and RNA-seq analyses

    Science.gov (United States)

    Edwards, Taylor; Tollis, Marc; Hsieh, PingHsun; Gutenkunst, Ryan N.; Liu, Zhen; Kusumi, Kenro; Culver, Melanie; Murphy, Robert W.

    2016-01-01

    Evolutionary biology often seeks to decipher the drivers of speciation, and much debate persists over the relative importance of isolation and gene flow in the formation of new species. Genetic studies of closely related species can assess if gene flow was present during speciation, because signatures of past introgression often persist in the genome. We test hypotheses on which mechanisms of speciation drove diversity among three distinct lineages of desert tortoise in the genus Gopherus. These lineages offer a powerful system to study speciation, because different biogeographic patterns (physical vs. ecological segregation) are observed at opposing ends of their distributions. We use 82 samples collected from 38 sites, representing the entire species' distribution and generate sequence data for mtDNA and four nuclear loci. A multilocus phylogenetic analysis in *BEAST estimates the species tree. RNA-seq data yield 20,126 synonymous variants from 7665 contigs from two individuals of each of the three lineages. Analyses of these data using the demographic inference package ∂a∂i serve to test the null hypothesis of no gene flow during divergence. The best-fit demographic model for the three taxa is concordant with the *BEAST species tree, and the ∂a∂i analysis does not indicate gene flow among any of the three lineages during their divergence. These analyses suggest that divergence among the lineages occurred in the absence of gene flow and in this scenario the genetic signature of ecological isolation (parapatric model) cannot be differentiated from geographic isolation (allopatric model).

  18. Interpreting energy scenarios

    Science.gov (United States)

    Iyer, Gokul; Edmonds, James

    2018-05-01

    Quantitative scenarios from energy-economic models inform decision-making about uncertain futures. Now, research shows the different ways these scenarios are subsequently used by users not involved in their initial development. In the absence of clear guidance from modellers, users may place too much or too little confidence in scenario assumptions and results.

  19. Fractal approach to computer-analytical modelling of tree crown

    International Nuclear Information System (INIS)

    Berezovskaya, F.S.; Karev, G.P.; Kisliuk, O.F.; Khlebopros, R.G.; Tcelniker, Yu.L.

    1993-09-01

    In this paper we discuss three approaches to the modeling of a tree crown development. These approaches are experimental (i.e. regressive), theoretical (i.e. analytical) and simulation (i.e. computer) modeling. The common assumption of these is that a tree can be regarded as one of the fractal objects which is the collection of semi-similar objects and combines the properties of two- and three-dimensional bodies. We show that a fractal measure of crown can be used as the link between the mathematical models of crown growth and light propagation through canopy. The computer approach gives the possibility to visualize a crown development and to calibrate the model on experimental data. In the paper different stages of the above-mentioned approaches are described. The experimental data for spruce, the description of computer system for modeling and the variant of computer model are presented. (author). 9 refs, 4 figs

  20. Assessment and modeling of inductive and non-inductive scenarios for ITER

    International Nuclear Information System (INIS)

    Boucher, D.; Vayakis, G.; Moreau, D.

    1999-01-01

    This paper presents recent developments in modeling and simulations of ITER performances and scenarios. The first part presents an improved modeling of coupled divertor/main plasma operation including the simulation of the measurements involved in the control loop. The second part explores the fusion performances predicted under non-inductive operation with internal transport barrier. The final part covers a detailed scenario for non-inductive operation using a reverse shear configuration with lower hybrid and fast wave current drive. (author)

  1. Spatial distribution of block falls using volumetric GIS-decision-tree models

    Science.gov (United States)

    Abdallah, C.

    2010-10-01

    Block falls are considered a significant aspect of surficial instability contributing to losses in land and socio-economic aspects through their damaging effects to natural and human environments. This paper predicts and maps the geographic distribution and volumes of block falls in central Lebanon using remote sensing, geographic information systems (GIS) and decision-tree modeling (un-pruned and pruned trees). Eleven terrain parameters (lithology, proximity to fault line, karst type, soil type, distance to drainage line, elevation, slope gradient, slope aspect, slope curvature, land cover/use, and proximity to roads) were generated to statistically explain the occurrence of block falls. The latter were discriminated using SPOT4 satellite imageries, and their dimensions were determined during field surveys. The un-pruned tree model based on all considered parameters explained 86% of the variability in field block fall measurements. Once pruned, it classifies 50% in block falls' volumes by selecting just four parameters (lithology, slope gradient, soil type, and land cover/use). Both tree models (un-pruned and pruned) were converted to quantitative 1:50,000 block falls' maps with different classes; starting from Nil (no block falls) to more than 4000 m 3. These maps are fairly matching with coincidence value equal to 45%; however, both can be used to prioritize the choice of specific zones for further measurement and modeling, as well as for land-use management. The proposed tree models are relatively simple, and may also be applied to other areas (i.e. the choice of un-pruned or pruned model is related to the availability of terrain parameters in a given area).

  2. Hydrochemical analysis of groundwater using a tree-based model

    Science.gov (United States)

    Litaor, M. Iggy; Brielmann, H.; Reichmann, O.; Shenker, M.

    2010-06-01

    SummaryHydrochemical indices are commonly used to ascertain aquifer characteristics, salinity problems, anthropogenic inputs and resource management, among others. This study was conducted to test the applicability of a binary decision tree model to aquifer evaluation using hydrochemical indices as input. The main advantage of the tree-based model compared to other commonly used statistical procedures such as cluster and factor analyses is the ability to classify groundwater samples with assigned probability and the reduction of a large data set into a few significant variables without creating new factors. We tested the model using data sets collected from headwater springs of the Jordan River, Israel. The model evaluation consisted of several levels of complexity, from simple separation between the calcium-magnesium-bicarbonate water type of karstic aquifers to the more challenging separation of calcium-sodium-bicarbonate water type flowing through perched and regional basaltic aquifers. In all cases, the model assigned measures for goodness of fit in the form of misclassification errors and singled out the most significant variable in the analysis. The model proceeded through a sequence of partitions providing insight into different possible pathways and changing lithology. The model results were extremely useful in constraining the interpretation of geological heterogeneity and constructing a conceptual flow model for a given aquifer. The tree model clearly identified the hydrochemical indices that were excluded from the analysis, thus providing information that can lead to a decrease in the number of routinely analyzed variables and a significant reduction in laboratory cost.

  3. Model checking software for phylogenetic trees using distribution and database methods

    Directory of Open Access Journals (Sweden)

    Requeno José Ignacio

    2013-12-01

    Full Text Available Model checking, a generic and formal paradigm stemming from computer science based on temporal logics, has been proposed for the study of biological properties that emerge from the labeling of the states defined over the phylogenetic tree. This strategy allows us to use generic software tools already present in the industry. However, the performance of traditional model checking is penalized when scaling the system for large phylogenies. To this end, two strategies are presented here. The first one consists of partitioning the phylogenetic tree into a set of subgraphs each one representing a subproblem to be verified so as to speed up the computation time and distribute the memory consumption. The second strategy is based on uncoupling the information associated to each state of the phylogenetic tree (mainly, the DNA sequence and exporting it to an external tool for the management of large information systems. The integration of all these approaches outperforms the results of monolithic model checking and helps us to execute the verification of properties in a real phylogenetic tree.

  4. Decision-Tree Models of Categorization Response Times, Choice Proportions, and Typicality Judgments

    Science.gov (United States)

    Lafond, Daniel; Lacouture, Yves; Cohen, Andrew L.

    2009-01-01

    The authors present 3 decision-tree models of categorization adapted from T. Trabasso, H. Rollins, and E. Shaughnessy (1971) and use them to provide a quantitative account of categorization response times, choice proportions, and typicality judgments at the individual-participant level. In Experiment 1, the decision-tree models were fit to…

  5. Context trees for privacy-preserving modeling of genetic data

    NARCIS (Netherlands)

    Kusters, C.J.; Ignatenko, T.

    2016-01-01

    In this work, we use context trees for privacypreserving modeling of genetic sequences. The resulting estimated models are applied for functional comparison of genetic sequences in a privacy preserving way. Here we define privacy as uncertainty about the genetic source sequence given its model and

  6. A diagnostic tree model for polytomous responses with multiple strategies.

    Science.gov (United States)

    Ma, Wenchao

    2018-04-23

    Constructed-response items have been shown to be appropriate for cognitively diagnostic assessments because students' problem-solving procedures can be observed, providing direct evidence for making inferences about their proficiency. However, multiple strategies used by students make item scoring and psychometric analyses challenging. This study introduces the so-called two-digit scoring scheme into diagnostic assessments to record both students' partial credits and their strategies. This study also proposes a diagnostic tree model (DTM) by integrating the cognitive diagnosis models with the tree model to analyse the items scored using the two-digit rubrics. Both convergent and divergent tree structures are considered to accommodate various scoring rules. The MMLE/EM algorithm is used for item parameter estimation of the DTM, and has been shown to provide good parameter recovery under varied conditions in a simulation study. A set of data from TIMSS 2007 mathematics assessment is analysed to illustrate the use of the two-digit scoring scheme and the DTM. © 2018 The British Psychological Society.

  7. Modeling tree crown dynamics with 3D partial differential equations.

    Science.gov (United States)

    Beyer, Robert; Letort, Véronique; Cournède, Paul-Henry

    2014-01-01

    We characterize a tree's spatial foliage distribution by the local leaf area density. Considering this spatially continuous variable allows to describe the spatiotemporal evolution of the tree crown by means of 3D partial differential equations. These offer a framework to rigorously take locally and adaptively acting effects into account, notably the growth toward light. Biomass production through photosynthesis and the allocation to foliage and wood are readily included in this model framework. The system of equations stands out due to its inherent dynamic property of self-organization and spontaneous adaptation, generating complex behavior from even only a few parameters. The density-based approach yields spatially structured tree crowns without relying on detailed geometry. We present the methodological fundamentals of such a modeling approach and discuss further prospects and applications.

  8. Model trees for identifying exceptional players in the NHL and NBA draft

    OpenAIRE

    Liu, Yejia

    2018-01-01

    Drafting players is crucial for a team’s success. We describe a data-driven interpretable approach for assessing prospects in the National Hockey League and National Basketball Association. Previous approaches have built a predictive model based on player features, or derived performance predictions from comparable players. Our work develops model tree learning, which incorporates strengths of both model-based and cohort-based approaches. A model tree partitions the feature space according to...

  9. Oncogenetic tree model of somatic mutations and DNA methylation in colon tumors.

    Science.gov (United States)

    Sweeney, Carol; Boucher, Kenneth M; Samowitz, Wade S; Wolff, Roger K; Albertsen, Hans; Curtin, Karen; Caan, Bette J; Slattery, Martha L

    2009-01-01

    Our understanding of somatic alterations in colon cancer has evolved from a concept of a series of events taking place in a single sequence to a recognition of multiple pathways. An oncogenetic tree is a model intended to describe the pathways and sequence of somatic alterations in carcinogenesis without assuming that tumors will fall in mutually exclusive categories. We applied this model to data on colon tumor somatic alterations. An oncogenetic tree model was built using data on mutations of TP53, KRAS2, APC, and BRAF genes, methylation at CpG sites of MLH1 and TP16 genes, methylation in tumor (MINT) markers, and microsatellite instability (MSI) for 971 colon tumors from a population-based series. Oncogenetic tree analysis resulted in a reproducible tree with three branches. The model represents methylation of MINT markers as initiating a branch and predisposing to MSI, methylation of MHL1 and TP16, and BRAF mutation. APC mutation is the first alteration in an independent branch and is followed by TP53 mutation. KRAS2 mutation was placed a third independent branch, implying that it neither depends on, nor predisposes to, the other alterations. Individual tumors were observed to have alteration patterns representing every combination of one, two, or all three branches. The oncogenetic tree model assumptions are appropriate for the observed heterogeneity of colon tumors, and the model produces a useful visual schematic of the sequence of events in pathways of colon carcinogenesis.

  10. A Model of Desired Performance in Phylogenetic Tree Construction for Teaching Evolution.

    Science.gov (United States)

    Brewer, Steven D.

    This research paper examines phylogenetic tree construction-a form of problem solving in biology-by studying the strategies and heuristics used by experts. One result of the research is the development of a model of desired performance for phylogenetic tree construction. A detailed description of the model and the sample problems which illustrate…

  11. Estimating tree bole volume using artificial neural network models for four species in Turkey.

    Science.gov (United States)

    Ozçelik, Ramazan; Diamantopoulou, Maria J; Brooks, John R; Wiant, Harry V

    2010-01-01

    Tree bole volumes of 89 Scots pine (Pinus sylvestris L.), 96 Brutian pine (Pinus brutia Ten.), 107 Cilicica fir (Abies cilicica Carr.) and 67 Cedar of Lebanon (Cedrus libani A. Rich.) trees were estimated using Artificial Neural Network (ANN) models. Neural networks offer a number of advantages including the ability to implicitly detect complex nonlinear relationships between input and output variables, which is very helpful in tree volume modeling. Two different neural network architectures were used and produced the Back propagation (BPANN) and the Cascade Correlation (CCANN) Artificial Neural Network models. In addition, tree bole volume estimates were compared to other established tree bole volume estimation techniques including the centroid method, taper equations, and existing standard volume tables. An overview of the features of ANNs and traditional methods is presented and the advantages and limitations of each one of them are discussed. For validation purposes, actual volumes were determined by aggregating the volumes of measured short sections (average 1 meter) of the tree bole using Smalian's formula. The results reported in this research suggest that the selected cascade correlation artificial neural network (CCANN) models are reliable for estimating the tree bole volume of the four examined tree species since they gave unbiased results and were superior to almost all methods in terms of error (%) expressed as the mean of the percentage errors. 2009 Elsevier Ltd. All rights reserved.

  12. Modeling Flood & Drought Scenario for Water Management in Porali River Basin, Balochistan

    Directory of Open Access Journals (Sweden)

    Shoaib Ahmed

    2013-12-01

    Full Text Available Recent history shows that floods have become a frequently occurring disaster in Balochistan, especially during monsoon season. Two rivers, river Porali and river Kud overflows, inundating its banks and causing destruction to cultivated land and property. This study is an attempt to identify flood prone areas of Porali river basin for future flood scenario and propose possible reservoir locations for excess flood water storage. Computer-based models Hydrological Simulation Program-FORTRAN (HSPF and HEC-river analysis system (HEC-RAS are used as tools to simulate existing and future flood and drought scenarios. Models are calibrated and validated using data from 3 weather stations, namely Wadh, Bela, and Uthal and stream flow data from two gauging stations. The highest and the lowest 10 years of precipitation data are extracted, from historic dataset of all stations, to attain future flooding and drought scenarios, respectively. Flood inundation map is generated highlighting agricultural prone land and settlements of the watershed. Using Digital Elevation Model (DEM and volume of water calculated from the flood scenario, possible locations for reservoirs are marked that can store excess water for the use in drought years. Flow and volume of water has also been simulated for drought scenario. Analyses show that 3 × 109 m3 of water available due to immense flooding that is sufficient for the survival for one drought year, as the volume of water for latter scenario is 2.9 × 108m3.

  13. Model and scenario variations in predicted number of generations of Spodoptera litura Fab. on peanut during future climate change scenario.

    Directory of Open Access Journals (Sweden)

    Mathukumalli Srinivasa Rao

    Full Text Available The present study features the estimation of number of generations of tobacco caterpillar, Spodoptera litura. Fab. on peanut crop at six locations in India using MarkSim, which provides General Circulation Model (GCM of future data on daily maximum (T.max, minimum (T.min air temperatures from six models viz., BCCR-BCM2.0, CNRM-CM3, CSIRO-Mk3.5, ECHams5, INCM-CM3.0 and MIROC3.2 along with an ensemble of the six from three emission scenarios (A2, A1B and B1. This data was used to predict the future pest scenarios following the growing degree days approach in four different climate periods viz., Baseline-1975, Near future (NF -2020, Distant future (DF-2050 and Very Distant future (VDF-2080. It is predicted that more generations would occur during the three future climate periods with significant variation among scenarios and models. Among the seven models, 1-2 additional generations were predicted during DF and VDF due to higher future temperatures in CNRM-CM3, ECHams5 & CSIRO-Mk3.5 models. The temperature projections of these models indicated that the generation time would decrease by 18-22% over baseline. Analysis of variance (ANOVA was used to partition the variation in the predicted number of generations and generation time of S. litura on peanut during crop season. Geographical location explained 34% of the total variation in number of generations, followed by time period (26%, model (1.74% and scenario (0.74%. The remaining 14% of the variation was explained by interactions. Increased number of generations and reduction of generation time across the six peanut growing locations of India suggest that the incidence of S. litura may increase due to projected increase in temperatures in future climate change periods.

  14. Estimation of miniature forest parameters, species, tree shape, and distance between canopies by means of Monte-Carlo based radiative transfer model with forestry surface model

    International Nuclear Information System (INIS)

    Ding, Y.; Arai, K.

    2007-01-01

    A method for estimation of forest parameters, species, tree shape, distance between canopies by means of Monte-Carlo based radiative transfer model with forestry surface model is proposed. The model is verified through experiments with the miniature model of forest, tree array of relatively small size of trees. Two types of miniature trees, ellipse-looking and cone-looking canopy are examined in the experiments. It is found that the proposed model and experimental results show a coincidence so that the proposed method is validated. It is also found that estimation of tree shape, trunk tree distance as well as distinction between deciduous or coniferous trees can be done with the proposed model. Furthermore, influences due to multiple reflections between trees and interaction between trees and under-laying grass are clarified with the proposed method

  15. On the distribution of interspecies correlation for Markov models of character evolution on Yule trees.

    Science.gov (United States)

    Mulder, Willem H; Crawford, Forrest W

    2015-01-07

    Efforts to reconstruct phylogenetic trees and understand evolutionary processes depend fundamentally on stochastic models of speciation and mutation. The simplest continuous-time model for speciation in phylogenetic trees is the Yule process, in which new species are "born" from existing lineages at a constant rate. Recent work has illuminated some of the structural properties of Yule trees, but it remains mostly unknown how these properties affect sequence and trait patterns observed at the tips of the phylogenetic tree. Understanding the interplay between speciation and mutation under simple models of evolution is essential for deriving valid phylogenetic inference methods and gives insight into the optimal design of phylogenetic studies. In this work, we derive the probability distribution of interspecies covariance under Brownian motion and Ornstein-Uhlenbeck models of phenotypic change on a Yule tree. We compute the probability distribution of the number of mutations shared between two randomly chosen taxa in a Yule tree under discrete Markov mutation models. Our results suggest summary measures of phylogenetic information content, illuminate the correlation between site patterns in sequences or traits of related organisms, and provide heuristics for experimental design and reconstruction of phylogenetic trees. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Hydrodynamics of isohydric and anisohydric trees: insights from models and measurements

    Science.gov (United States)

    Novick, K. A.; Oishi, A. C.; Roman, D. T.; Benson, M. C.; Miniat, C.

    2016-12-01

    In an effort to understand and predict the mechanisms that govern tree response to hydrologic stress, plant hydraulic theory, which classifies trees along a continuum of isohydric to anisohydric water use strategies, is increasingly being used. Isohydry maintains relatively constant leaf water potential during periods of water stress, promoting wide hydraulic safety margins that reduce the risk of xylem cavitation. In contrast, anisohydry allows leaf water potential to fall as soil water potential falls, but in doing so trees incur a greater risk of hydraulic failure. As a result, unique patterns of stomatal functioning between isohydric and anisohydric species are both predicted and observed in leaf-, tree-, and stand-level water use. We use a novel model formulation to examine the dynamics of three mechanisms that are potentially limiting to leaf-level gas exchange in trees during drought: (1) a `demand limitation' driven by an assumption of stomatal optimization of water loss and carbon uptake; (2) `hydraulic limitation' of water movement from the roots to the leaves; and (3) `non-stomatal' limitations imposed by declining leaf water status within the leaf. Model results suggest that species-specific `economics' of stomatal behavior may play an important role in differentiating species along the continuum of isohydric to anisohydric behavior; specifically, we show that non-stomatal and demand limitations may reduce stomatal conductance and increase leaf water potential, promoting wide safety margins characteristic of isohydric species. Direct comparisons of modeled and measured stomatal conductance further indicated that non-stomatal and demand limitations reproduced observed patterns of tree water use well for an isohydric species but that a hydraulic limitation likely applies in the case of an anisohydric species. This modeling framework used in concert with climate data may help land managers and scientists predict when and what forest species and communities

  17. Function-centered modeling of engineering systems using the goal tree-success tree technique and functional primitives

    International Nuclear Information System (INIS)

    Modarres, Mohammad; Cheon, Se Woo

    1999-01-01

    Most of the complex systems are formed through some hierarchical evolution. Therefore, those systems can be best described through hierarchical frameworks. This paper describes some fundamental attributes of complex physical systems and several hierarchies such as functional, behavioral, goal/condition, and event hierarchies, then presents a function-centered approach to system modeling. Based on the function-centered concept, this paper describes the joint goal tree-success tree (GTST) and the master logic diagram (MLD) as a framework for developing models of complex physical systems. A function-based lexicon for classifying the most common elements of engineering systems for use in the GTST-MLD framework has been proposed. The classification is based on the physical conservation laws that govern the engineering systems. Functional descriptions based on conservation laws provide a simple and rich vocabulary for modeling complex engineering systems

  18. DG TO FT - AUTOMATIC TRANSLATION OF DIGRAPH TO FAULT TREE MODELS

    Science.gov (United States)

    Iverson, D. L.

    1994-01-01

    Fault tree and digraph models are frequently used for system failure analysis. Both types of models represent a failure space view of the system using AND and OR nodes in a directed graph structure. Each model has its advantages. While digraphs can be derived in a fairly straightforward manner from system schematics and knowledge about component failure modes and system design, fault tree structure allows for fast processing using efficient techniques developed for tree data structures. The similarities between digraphs and fault trees permits the information encoded in the digraph to be translated into a logically equivalent fault tree. The DG TO FT translation tool will automatically translate digraph models, including those with loops or cycles, into fault tree models that have the same minimum cut set solutions as the input digraph. This tool could be useful, for example, if some parts of a system have been modeled using digraphs and others using fault trees. The digraphs could be translated and incorporated into the fault trees, allowing them to be analyzed using a number of powerful fault tree processing codes, such as cut set and quantitative solution codes. A cut set for a given node is a group of failure events that will cause the failure of the node. A minimum cut set for a node is any cut set that, if any of the failures in the set were to be removed, the occurrence of the other failures in the set will not cause the failure of the event represented by the node. Cut sets calculations can be used to find dependencies, weak links, and vital system components whose failures would cause serious systems failure. The DG TO FT translation system reads in a digraph with each node listed as a separate object in the input file. The user specifies a terminal node for the digraph that will be used as the top node of the resulting fault tree. A fault tree basic event node representing the failure of that digraph node is created and becomes a child of the terminal

  19. Determining the Role of Sediment Deposition and Transport in the Formation and Maintenance of Tree Islands in the Florida Everglades

    Science.gov (United States)

    Mitchell-Bruker, S.; Childers, D.; Ross, M.; Leonard, L.; Solo-Gabriel, H.; Stothoff, S.

    2002-05-01

    gradients on tree islands and in the surrounding marsh. These data will be analyzed using statistical and hydrologic models to test the hypothesis that surface water flow is an essential force in forming and maintaining tree islands. A sediment and nutrient transport model is being developed to apply these data to scenarios for flow in a vegetated wetland. By constraining model parameters to the limits supported by these data, the full range of possible flow and transport scenarios can be tested in the model. These model results, along with statistical analysis will be used to support or reject the hypothesis that sediment and nutrient transport are key components in the formation of hardwood hammock and bay head tree islands.

  20. Building classification trees to explain the radioactive contamination levels of the plants

    International Nuclear Information System (INIS)

    Briand, B.

    2008-04-01

    The objective of this thesis is the development of a method allowing the identification of factors leading to various radioactive contamination levels of the plants. The methodology suggested is based on the use of a radioecological transfer model of the radionuclides through the environment (A.S.T.R.A.L. computer code) and a classification-tree method. Particularly, to avoid the instability problems of classification trees and to preserve the tree structure, a node level stabilizing technique is used. Empirical comparisons are carried out between classification trees built by this method (called R.E.N. method) and those obtained by the C.A.R.T. method. A similarity measure is defined to compare the structure of two classification trees. This measure is used to study the stabilizing performance of the R.E.N. method. The methodology suggested is applied to a simplified contamination scenario. By the results obtained, we can identify the main variables responsible of the various radioactive contamination levels of four leafy-vegetables (lettuce, cabbage, spinach and leek). Some extracted rules from these classification trees can be usable in a post-accidental context. (author)

  1. Not seeing the forest for the trees: size of the minimum spanning trees (MSTs) forest and branch significance in MST-based phylogenetic analysis.

    Science.gov (United States)

    Teixeira, Andreia Sofia; Monteiro, Pedro T; Carriço, João A; Ramirez, Mário; Francisco, Alexandre P

    2015-01-01

    Trees, including minimum spanning trees (MSTs), are commonly used in phylogenetic studies. But, for the research community, it may be unclear that the presented tree is just a hypothesis, chosen from among many possible alternatives. In this scenario, it is important to quantify our confidence in both the trees and the branches/edges included in such trees. In this paper, we address this problem for MSTs by introducing a new edge betweenness metric for undirected and weighted graphs. This spanning edge betweenness metric is defined as the fraction of equivalent MSTs where a given edge is present. The metric provides a per edge statistic that is similar to that of the bootstrap approach frequently used in phylogenetics to support the grouping of taxa. We provide methods for the exact computation of this metric based on the well known Kirchhoff's matrix tree theorem. Moreover, we implement and make available a module for the PHYLOViZ software and evaluate the proposed metric concerning both effectiveness and computational performance. Analysis of trees generated using multilocus sequence typing data (MLST) and the goeBURST algorithm revealed that the space of possible MSTs in real data sets is extremely large. Selection of the edge to be represented using bootstrap could lead to unreliable results since alternative edges are present in the same fraction of equivalent MSTs. The choice of the MST to be presented, results from criteria implemented in the algorithm that must be based in biologically plausible models.

  2. Functional Traits and Water Transport Strategies in Lowland Tropical Rainforest Trees

    Science.gov (United States)

    Apgaua, Deborah M. G.; Ishida, Françoise Y.; Tng, David Y. P.; Laidlaw, Melinda J.; Santos, Rubens M.; Rumman, Rizwana; Eamus, Derek; Holtum, Joseph A. M.; Laurance, Susan G. W.

    2015-01-01

    Understanding how tropical rainforest trees may respond to the precipitation extremes predicted in future climate change scenarios is paramount for their conservation and management. Tree species clearly differ in drought susceptibility, suggesting that variable water transport strategies exist. Using a multi-disciplinary approach, we examined the hydraulic variability in trees in a lowland tropical rainforest in north-eastern Australia. We studied eight tree species representing broad plant functional groups (one palm and seven eudicot mature-phase, and early-successional trees). We characterised the species’ hydraulic system through maximum rates of volumetric sap flow and velocities using the heat ratio method, and measured rates of tree growth and several stem, vessel, and leaf traits. Sap flow measures exhibited limited variability across species, although early-successional species and palms had high mean sap velocities relative to most mature-phase species. Stem, vessel, and leaf traits were poor predictors of sap flow measures. However, these traits exhibited different associations in multivariate analysis, revealing gradients in some traits across species and alternative hydraulic strategies in others. Trait differences across and within tree functional groups reflect variation in water transport and drought resistance strategies. These varying strategies will help in our understanding of changing species distributions under predicted drought scenarios. PMID:26087009

  3. Functional Traits and Water Transport Strategies in Lowland Tropical Rainforest Trees.

    Directory of Open Access Journals (Sweden)

    Deborah M G Apgaua

    Full Text Available Understanding how tropical rainforest trees may respond to the precipitation extremes predicted in future climate change scenarios is paramount for their conservation and management. Tree species clearly differ in drought susceptibility, suggesting that variable water transport strategies exist. Using a multi-disciplinary approach, we examined the hydraulic variability in trees in a lowland tropical rainforest in north-eastern Australia. We studied eight tree species representing broad plant functional groups (one palm and seven eudicot mature-phase, and early-successional trees. We characterised the species' hydraulic system through maximum rates of volumetric sap flow and velocities using the heat ratio method, and measured rates of tree growth and several stem, vessel, and leaf traits. Sap flow measures exhibited limited variability across species, although early-successional species and palms had high mean sap velocities relative to most mature-phase species. Stem, vessel, and leaf traits were poor predictors of sap flow measures. However, these traits exhibited different associations in multivariate analysis, revealing gradients in some traits across species and alternative hydraulic strategies in others. Trait differences across and within tree functional groups reflect variation in water transport and drought resistance strategies. These varying strategies will help in our understanding of changing species distributions under predicted drought scenarios.

  4. Functional Traits and Water Transport Strategies in Lowland Tropical Rainforest Trees.

    Science.gov (United States)

    Apgaua, Deborah M G; Ishida, Françoise Y; Tng, David Y P; Laidlaw, Melinda J; Santos, Rubens M; Rumman, Rizwana; Eamus, Derek; Holtum, Joseph A M; Laurance, Susan G W

    2015-01-01

    Understanding how tropical rainforest trees may respond to the precipitation extremes predicted in future climate change scenarios is paramount for their conservation and management. Tree species clearly differ in drought susceptibility, suggesting that variable water transport strategies exist. Using a multi-disciplinary approach, we examined the hydraulic variability in trees in a lowland tropical rainforest in north-eastern Australia. We studied eight tree species representing broad plant functional groups (one palm and seven eudicot mature-phase, and early-successional trees). We characterised the species' hydraulic system through maximum rates of volumetric sap flow and velocities using the heat ratio method, and measured rates of tree growth and several stem, vessel, and leaf traits. Sap flow measures exhibited limited variability across species, although early-successional species and palms had high mean sap velocities relative to most mature-phase species. Stem, vessel, and leaf traits were poor predictors of sap flow measures. However, these traits exhibited different associations in multivariate analysis, revealing gradients in some traits across species and alternative hydraulic strategies in others. Trait differences across and within tree functional groups reflect variation in water transport and drought resistance strategies. These varying strategies will help in our understanding of changing species distributions under predicted drought scenarios.

  5. Predictive mapping of soil organic carbon in wet cultivated lands using classification-tree based models

    DEFF Research Database (Denmark)

    Kheir, Rania Bou; Greve, Mogens Humlekrog; Bøcher, Peder Klith

    2010-01-01

    the geographic distribution of SOC across Denmark using remote sensing (RS), geographic information systems (GISs) and decision-tree modeling (un-pruned and pruned classification trees). Seventeen parameters, i.e. parent material, soil type, landscape type, elevation, slope gradient, slope aspect, mean curvature...... field measurements in the area of interest (Denmark). A large number of tree-based classification models (588) were developed using (i) all of the parameters, (ii) all Digital Elevation Model (DEM) parameters only, (iii) the primary DEM parameters only, (iv), the remote sensing (RS) indices only, (v......) selected pairs of parameters, (vi) soil type, parent material and landscape type only, and (vii) the parameters having a high impact on SOC distribution in built pruned trees. The best constructed classification tree models (in the number of three) with the lowest misclassification error (ME...

  6. Development of a model of the coronary arterial tree for the 4D XCAT phantom

    International Nuclear Information System (INIS)

    Fung, George S K; Tsui, Benjamin M W; Segars, W Paul; Gullberg, Grant T

    2011-01-01

    A detailed three-dimensional (3D) model of the coronary artery tree with cardiac motion has great potential for applications in a wide variety of medical imaging research areas. In this work, we first developed a computer-generated 3D model of the coronary arterial tree for the heart in the extended cardiac-torso (XCAT) phantom, thereby creating a realistic computer model of the human anatomy. The coronary arterial tree model was based on two datasets: (1) a gated cardiac dual-source computed tomography (CT) angiographic dataset obtained from a normal human subject and (2) statistical morphometric data of porcine hearts. The initial proximal segments of the vasculature and the anatomical details of the boundaries of the ventricles were defined by segmenting the CT data. An iterative rule-based generation method was developed and applied to extend the coronary arterial tree beyond the initial proximal segments. The algorithm was governed by three factors: (1) statistical morphometric measurements of the connectivity, lengths and diameters of the arterial segments; (2) avoidance forces from other vessel segments and the boundaries of the myocardium, and (3) optimality principles which minimize the drag force at the bifurcations of the generated tree. Using this algorithm, the 3D computational model of the largest six orders of the coronary arterial tree was generated, which spread across the myocardium of the left and right ventricles. The 3D coronary arterial tree model was then extended to 4D to simulate different cardiac phases by deforming the original 3D model according to the motion vector map of the 4D cardiac model of the XCAT phantom at the corresponding phases. As a result, a detailed and realistic 4D model of the coronary arterial tree was developed for the XCAT phantom by imposing constraints of anatomical and physiological characteristics of the coronary vasculature. This new 4D coronary artery tree model provides a unique simulation tool that can be

  7. Driving-forces model on individual behavior in scenarios considering moving threat agents

    Science.gov (United States)

    Li, Shuying; Zhuang, Jun; Shen, Shifei; Wang, Jia

    2017-09-01

    The individual behavior model is a contributory factor to improve the accuracy of agent-based simulation in different scenarios. However, few studies have considered moving threat agents, which often occur in terrorist attacks caused by attackers with close-range weapons (e.g., sword, stick). At the same time, many existing behavior models lack validation from cases or experiments. This paper builds a new individual behavior model based on seven behavioral hypotheses. The driving-forces model is an extension of the classical social force model considering scenarios including moving threat agents. An experiment was conducted to validate the key components of the model. Then the model is compared with an advanced Elliptical Specification II social force model, by calculating the fitting errors between the simulated and experimental trajectories, and being applied to simulate a specific circumstance. Our results show that the driving-forces model reduced the fitting error by an average of 33.9% and the standard deviation by an average of 44.5%, which indicates the accuracy and stability of the model in the studied situation. The new driving-forces model could be used to simulate individual behavior when analyzing the risk of specific scenarios using agent-based simulation methods, such as risk analysis of close-range terrorist attacks in public places.

  8. Rogeaulito: A World Energy Scenario Modeling Tool for Transparent Energy System Thinking

    International Nuclear Information System (INIS)

    Benichou, Léo; Mayr, Sebastian

    2014-01-01

    Rogeaulito is a world energy model for scenario building developed by the European think tank The Shift Project. It’s a tool to explore world energy choices from a very long-term and systematic perspective. As a key feature and novelty it computes energy supply and demand independently from each other revealing potentially missing energy supply by 2100. It is further simple to use, didactic, and open source. As such, it targets a broad user group and advocates for reproducibility and transparency in scenario modeling as well as model-based learning. Rogeaulito applies an engineering approach using disaggregated data in a spreadsheet model.

  9. Rogeaulito: A World Energy Scenario Modeling Tool for Transparent Energy System Thinking

    Energy Technology Data Exchange (ETDEWEB)

    Benichou, Léo, E-mail: leo.benichou@theshiftproject.org [The Shift Project, Paris (France); Mayr, Sebastian, E-mail: communication@theshiftproject.org [Paris School of International Affairs, Sciences Po., Paris (France)

    2014-01-13

    Rogeaulito is a world energy model for scenario building developed by the European think tank The Shift Project. It’s a tool to explore world energy choices from a very long-term and systematic perspective. As a key feature and novelty it computes energy supply and demand independently from each other revealing potentially missing energy supply by 2100. It is further simple to use, didactic, and open source. As such, it targets a broad user group and advocates for reproducibility and transparency in scenario modeling as well as model-based learning. Rogeaulito applies an engineering approach using disaggregated data in a spreadsheet model.

  10. Quantitative Verification and Synthesis of Attack-Defence Scenarios Conference

    NARCIS (Netherlands)

    Aslanyan, Zaruhi; Nielson, Flemming; Parker, David

    Attack-defence trees are a powerful technique for formally evaluating attack-defence scenarios. They represent in an intuitive, graphical way the interaction between an attacker and a defender who compete in order to achieve conflicting objectives. We propose a novel framework for the formal

  11. Economic impacts of climate change. Flooding and salinity in scenarios, models and cases

    International Nuclear Information System (INIS)

    Jonkhoff, W.; Koops, O.; Van der Krogt, R.; Oude Essink, G.; Rietveld, E.

    2008-07-01

    In this report, climatic and economic scenarios are combined and future risks are calculated for the consequences of climate change, such as a rising sea level, flooding, extreme draughts and salinity. The calculation of these economic effects of climate change are based on climate scenarios of the KNMI (Royal Dutch Meteorological Institute), TNO's RAEM model (Spatial General Economic Model), the high tide information system of the Dutch Ministry of Waterways and Public Works and the Space scanner of the Environmental Assessment Agency. Next to information on scenarios and models, this report also addresses damage calculations of flooding near Lopik and Ter Heide. The report ends with policy recommendations for adaptation policy. [mk] [nl

  12. TreePOD: Sensitivity-Aware Selection of Pareto-Optimal Decision Trees.

    Science.gov (United States)

    Muhlbacher, Thomas; Linhardt, Lorenz; Moller, Torsten; Piringer, Harald

    2018-01-01

    Balancing accuracy gains with other objectives such as interpretability is a key challenge when building decision trees. However, this process is difficult to automate because it involves know-how about the domain as well as the purpose of the model. This paper presents TreePOD, a new approach for sensitivity-aware model selection along trade-offs. TreePOD is based on exploring a large set of candidate trees generated by sampling the parameters of tree construction algorithms. Based on this set, visualizations of quantitative and qualitative tree aspects provide a comprehensive overview of possible tree characteristics. Along trade-offs between two objectives, TreePOD provides efficient selection guidance by focusing on Pareto-optimal tree candidates. TreePOD also conveys the sensitivities of tree characteristics on variations of selected parameters by extending the tree generation process with a full-factorial sampling. We demonstrate how TreePOD supports a variety of tasks involved in decision tree selection and describe its integration in a holistic workflow for building and selecting decision trees. For evaluation, we illustrate a case study for predicting critical power grid states, and we report qualitative feedback from domain experts in the energy sector. This feedback suggests that TreePOD enables users with and without statistical background a confident and efficient identification of suitable decision trees.

  13. Hierarchical Multinomial Processing Tree Models: A Latent-Trait Approach

    Science.gov (United States)

    Klauer, Karl Christoph

    2010-01-01

    Multinomial processing tree models are widely used in many areas of psychology. A hierarchical extension of the model class is proposed, using a multivariate normal distribution of person-level parameters with the mean and covariance matrix to be estimated from the data. The hierarchical model allows one to take variability between persons into…

  14. iTree-Hydro: Snow hydrology update for the urban forest hydrology model

    Science.gov (United States)

    Yang Yang; Theodore A. Endreny; David J. Nowak

    2011-01-01

    This article presents snow hydrology updates made to iTree-Hydro, previously called the Urban Forest Effects—Hydrology model. iTree-Hydro Version 1 was a warm climate model developed by the USDA Forest Service to provide a process-based planning tool with robust water quantity and quality predictions given data limitations common to most urban areas. Cold climate...

  15. Selection the Optimum Suppliers Compound Using a Mixed Model of MADM and Fault Tree Analysis

    Directory of Open Access Journals (Sweden)

    Meysam Azimian

    2017-03-01

    Full Text Available In this paper, an integrated approach of MADM and fault tree analysis (FTA is provided for determining the most reliable combination of suppliers for a strategic product in IUT University. At first, risks of suppliers is estimated by defining the indices for evaluating them, determining their relative status indices and using satisfying and SAW methods. Then, intrinsic risks of utilized equipments in the products are qualified and the final integrated risk for equipments is determined. Finally, through all the different scenarios, the best composition of equipment suppliers is selected by defining the palpable top events and fault tree analysis. The contribution of this paper is about proposing an integrated method of MADM and FTA to determine the most reliable suppliers in order to minimize the final risk of providing a product.

  16. Reconstructing 3D Tree Models Using Motion Capture and Particle Flow

    Directory of Open Access Journals (Sweden)

    Jie Long

    2013-01-01

    Full Text Available Recovering tree shape from motion capture data is a first step toward efficient and accurate animation of trees in wind using motion capture data. Existing algorithms for generating models of tree branching structures for image synthesis in computer graphics are not adapted to the unique data set provided by motion capture. We present a method for tree shape reconstruction using particle flow on input data obtained from a passive optical motion capture system. Initial branch tip positions are estimated from averaged and smoothed motion capture data. Branch tips, as particles, are also generated within a bounding space defined by a stack of bounding boxes or a convex hull. The particle flow, starting at branch tips within the bounding volume under forces, creates tree branches. The forces are composed of gravity, internal force, and external force. The resulting shapes are realistic and similar to the original tree crown shape. Several tunable parameters provide control over branch shape and arrangement.

  17. Study on reliability analysis based on multilevel flow models and fault tree method

    International Nuclear Information System (INIS)

    Chen Qiang; Yang Ming

    2014-01-01

    Multilevel flow models (MFM) and fault tree method describe the system knowledge in different forms, so the two methods express an equivalent logic of the system reliability under the same boundary conditions and assumptions. Based on this and combined with the characteristics of MFM, a method mapping MFM to fault tree was put forward, thus providing a way to establish fault tree rapidly and realizing qualitative reliability analysis based on MFM. Taking the safety injection system of pressurized water reactor nuclear power plant as an example, its MFM was established and its reliability was analyzed qualitatively. The analysis result shows that the logic of mapping MFM to fault tree is correct. The MFM is easily understood, created and modified. Compared with the traditional fault tree analysis, the workload is greatly reduced and the modeling time is saved. (authors)

  18. MODELING BILL-OF-MATERIAL WITH TREE DATA STRUCTURE: CASE STUDY IN FURNITURE MANUFACTURER

    Directory of Open Access Journals (Sweden)

    Toni Prahasto

    2012-02-01

    Full Text Available This paper presents a modeling of Bill-of-Material with tree data structure. The BOM represents wooden furniture products. The management of BOM is incorporated into an MRP software which is specially built for a furniture manufacturer. The tree data structure is approached with an object oriented programming to provide the creation and modification of the data. The tree object is designed so that a downstream programmer can create an application with high productivity, using the BOM object of course. Legality of the development is ensured by adapting open source resources, i.e. MySQL database engine, PHP server script, and client-side Javascript. The BOM object is used extensively in the MRP software that is being developed. A couple of screenshots are presented to demonstrate the ease of creation and manipulation of Bill-of-Material. The proper approach of modeling BOM with tree structure allows the programmer to reach high productivity during the development of the aforementioned MRP customized software. Keyword : Modeling, Bill of Material, Tree Data Structure

  19. A maximum pseudo-likelihood approach for estimating species trees under the coalescent model

    Directory of Open Access Journals (Sweden)

    Edwards Scott V

    2010-10-01

    Full Text Available Abstract Background Several phylogenetic approaches have been developed to estimate species trees from collections of gene trees. However, maximum likelihood approaches for estimating species trees under the coalescent model are limited. Although the likelihood of a species tree under the multispecies coalescent model has already been derived by Rannala and Yang, it can be shown that the maximum likelihood estimate (MLE of the species tree (topology, branch lengths, and population sizes from gene trees under this formula does not exist. In this paper, we develop a pseudo-likelihood function of the species tree to obtain maximum pseudo-likelihood estimates (MPE of species trees, with branch lengths of the species tree in coalescent units. Results We show that the MPE of the species tree is statistically consistent as the number M of genes goes to infinity. In addition, the probability that the MPE of the species tree matches the true species tree converges to 1 at rate O(M -1. The simulation results confirm that the maximum pseudo-likelihood approach is statistically consistent even when the species tree is in the anomaly zone. We applied our method, Maximum Pseudo-likelihood for Estimating Species Trees (MP-EST to a mammal dataset. The four major clades found in the MP-EST tree are consistent with those in the Bayesian concatenation tree. The bootstrap supports for the species tree estimated by the MP-EST method are more reasonable than the posterior probability supports given by the Bayesian concatenation method in reflecting the level of uncertainty in gene trees and controversies over the relationship of four major groups of placental mammals. Conclusions MP-EST can consistently estimate the topology and branch lengths (in coalescent units of the species tree. Although the pseudo-likelihood is derived from coalescent theory, and assumes no gene flow or horizontal gene transfer (HGT, the MP-EST method is robust to a small amount of HGT in the

  20. Dimensional Reduction for the General Markov Model on Phylogenetic Trees.

    Science.gov (United States)

    Sumner, Jeremy G

    2017-03-01

    We present a method of dimensional reduction for the general Markov model of sequence evolution on a phylogenetic tree. We show that taking certain linear combinations of the associated random variables (site pattern counts) reduces the dimensionality of the model from exponential in the number of extant taxa, to quadratic in the number of taxa, while retaining the ability to statistically identify phylogenetic divergence events. A key feature is the identification of an invariant subspace which depends only bilinearly on the model parameters, in contrast to the usual multi-linear dependence in the full space. We discuss potential applications including the computation of split (edge) weights on phylogenetic trees from observed sequence data.

  1. Dynamic simulation of sustainable farm development scenarios using cognitive modeling

    Directory of Open Access Journals (Sweden)

    Tuzhyk Kateryna

    2017-03-01

    Full Text Available Dynamic simulation of sustainable farm development scenarios using cognitive modeling. The paper presents a dynamic simulation system of sustainable development scenarios on farms using cognitive modeling. The system incorporates relevant variables which affect the sustainable development of farms. Its user provides answers to strategic issues connected with the level of farm sustainability over a long-term perspective of dynamic development. The work contains a description of the model structure as well as the results of simulations carried out on 16 farms in northern Ukraine. The results show that the process of sustainability is based mainly on the potential for innovation in agricultural production and biodiversity. The user is able to simulate various scenarios for the sustainable development of a farm and visualize the influence of factors on the economic and social situation, as well as on environmental aspects. Upon carrying out a series of simulations, it was determined that the development of farms characterized by sustainable development is based on additional profit, which serves as the main motivation for transforming a conventional farm into a sustainable one. Nevertheless, additional profit is not the only driving force in the system of sustainable development. The standard of living, market condition, and legal regulations as well as government support also play a significant motivational role.

  2. Riparian vegetation structure under desertification scenarios

    Science.gov (United States)

    Rosário Fernandes, M.; Segurado, Pedro; Jauch, Eduardo; Ferreira, M. Teresa

    2015-04-01

    Riparian areas are responsible for many ecological and ecosystems services, including the filtering function, that are considered crucial to the preservation of water quality and social benefits. The main goal of this study is to quantify and understand the riparian variability under desertification scenario(s) and identify the optimal riparian indicators for water scarcity and droughts (WS&D), henceforth improving river basin management. This study was performed in the Iberian Tâmega basin, using riparian woody patches, mapped by visual interpretation on Google Earth imagery, along 130 Sampling Units of 250 m long river stretches. Eight riparian structural indicators, related with lateral dimension, weighted area and shape complexity of riparian patches were calculated using Patch Analyst extension for ArcGis 10. A set of 29 hydrological, climatic, and hydrogeomorphological variables were computed, by a water modelling system (MOHID), using monthly meteorological data between 2008 and 2014. Land-use classes were also calculated, in a 250m-buffer surrounding each sampling unit, using a classification based system on Corine Land Cover. Boosted Regression Trees identified Mean-width (MW) as the optimal riparian indicator for water scarcity and drought, followed by the Weighted Class Area (WCA) (classification accuracy =0.79 and 0.69 respectively). Average Flow and Strahler number were consistently selected, by all boosted models, as the most important explanatory variables. However, a combined effect of hidrogeomorphology and land-use can explain the high variability found in the riparian width mainly in Tâmega tributaries. Riparian patches are larger towards Tâmega river mouth although with lower shape complexity, probably related with more continuous and almost monospecific stands. Climatic, hydrological and land use scenarios, singly and combined, were used to quantify the riparian variability responding to these changes, and to assess the loss of riparian

  3. Stochastic Channel Modeling for Railway Tunnel Scenarios at 25 GHz

    Directory of Open Access Journals (Sweden)

    Danping He

    2018-02-01

    Full Text Available More people prefer using rail traffic for travel or for commuting owing to its convenience and flexibility. The railway scenario has become an important communication scenario in the fifth generation era. The communication system should be designed to support high‐data‐rate demands with seamless connectivity at a high mobility. In this paper, the channel characteristics are studied and modeled for the railway tunnel scenario with straight and curved route shapes. On the basis of measurements using the “Mobile Hotspot Network” system, a three‐dimensional ray tracer (RT is calibrated and validated for the target scenarios. More channel characteristics are explored via RT simulations at 25.25 GHz with a 500‐MHz bandwidth. The key channel parameters are extracted, provided, and incorporated into a 3rd‐Generation‐Partnership‐Project‐like stochastic channel generator. The necessary channel information can be practically realized, which can support the link‐level and system‐level design of the communication system in similar scenarios.

  4. THM modelling of buffer, backfill and other system components. Critical processes and scenarios

    International Nuclear Information System (INIS)

    Aakesson, Mattias; Kristensson, Ola; Boergesson, Lennart; Dueck, Ann; Hernelind, Jan

    2010-03-01

    A number of critical thermo-hydro-mechanical processes and scenarios for the buffer, tunnel backfill and other filling components in the repository have been identified. These processes and scenarios representing different aspects of the repository evolution have been pinpointed and modelled. In total, 22 cases have been modelled. Most cases have been analysed with finite element (FE) calculations, using primarily the two codes Abaqus and Code B right. For some cases analytical methods have been used either to supplement the FE calculations or due to that the scenario has a character that makes it unsuitable or very difficult to use the FE method. Material models and element models and choice of parameters as well as presumptions have been stated for all modelling cases. In addition, the results have been analysed and conclusions drawn for each case. The uncertainties have also been analysed. Besides the information given for all cases studied, the codes and material models have been described in a separate so called data report

  5. THM modelling of buffer, backfill and other system components. Critical processes and scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Aakesson, Mattias; Kristensson, Ola; Boergesson, Lennart; Dueck, Ann (Clay Technology AB, Lund (Sweden)); Hernelind, Jan (5T-Engineering AB, Vaesteraas (Sweden))

    2010-03-15

    A number of critical thermo-hydro-mechanical processes and scenarios for the buffer, tunnel backfill and other filling components in the repository have been identified. These processes and scenarios representing different aspects of the repository evolution have been pinpointed and modelled. In total, 22 cases have been modelled. Most cases have been analysed with finite element (FE) calculations, using primarily the two codes Abaqus and Code-Bright. For some cases analytical methods have been used either to supplement the FE calculations or due to that the scenario has a character that makes it unsuitable or very difficult to use the FE method. Material models and element models and choice of parameters as well as presumptions have been stated for all modelling cases. In addition, the results have been analysed and conclusions drawn for each case. The uncertainties have also been analysed. Besides the information given for all cases studied, the codes and material models have been described in a separate so called data report

  6. 3D modeling of olive tree and simulating the harvesting forces

    Directory of Open Access Journals (Sweden)

    Glăvan Dan Ovidiu

    2017-01-01

    Full Text Available The paper presents the results of the study regarding the influence of shaking forces on olive tree harvesting systems. Shaking forces can be released through several methods. Important is the end result, namely the shaking force and the cadence of shaking speed. Mechanical and automatic harvesting methods collect more olives than traditional methods but may damage the olive trees. In order to prevent this damage, we need to calculate the necessary shaking force. An original research method is proposed to simulate shaking forces using a 3D olive tree model with Autodesk Inventor software. In the experiments, we use different shaking forces and various shaking speeds. We also use different diameters of the olive tree trunk. We analyze the results from this experiment to determine the optimal shaking force for harvesting olives without damaging the olive tree.

  7. Applying and Individual-Based Model to Simultaneously Evaluate Net Ecosystem Production and Tree Diameter Increment

    Science.gov (United States)

    Fang, F. J.

    2017-12-01

    Reconciling observations at fundamentally different scales is central in understanding the global carbon cycle. This study investigates a model-based melding of forest inventory data, remote-sensing data and micrometeorological-station data ("flux towers" estimating forest heat, CO2 and H2O fluxes). The individual tree-based model FORCCHN was used to evaluate the tree DBH increment and forest carbon fluxes. These are the first simultaneous simulations of the forest carbon budgets from flux towers and individual-tree growth estimates of forest carbon budgets using the continuous forest inventory data — under circumstances in which both predictions can be tested. Along with the global implications of such findings, this also improves the capacity for forest sustainable management and the comprehensive understanding of forest ecosystems. In forest ecology, diameter at breast height (DBH) of a tree significantly determines an individual tree's cross-sectional sapwood area, its biomass and carbon storage. Evaluation the annual DBH increment (ΔDBH) of an individual tree is central to understanding tree growth and forest ecology. Ecosystem Carbon flux is a consequence of key ecosystem processes in the forest-ecosystem carbon cycle, Gross and Net Primary Production (GPP and NPP, respectively) and Net Ecosystem Respiration (NEP). All of these closely relate with tree DBH changes and tree death. Despite advances in evaluating forest carbon fluxes with flux towers and forest inventories for individual tree ΔDBH, few current ecological models can simultaneously quantify and predict the tree ΔDBH and forest carbon flux.

  8. Modeling of air pollutant removal by dry deposition to urban trees using a WRF/CMAQ/i-Tree Eco coupled system

    Science.gov (United States)

    Maria Theresa I. Cabaraban; Charles N. Kroll; Satoshi Hirabayashi; David J. Nowak

    2013-01-01

    A distributed adaptation of i-Tree Eco was used to simulate dry deposition in an urban area. This investigation focused on the effects of varying temperature, LAI, and NO2 concentration inputs on estimated NO2 dry deposition to trees in Baltimore, MD. A coupled modeling system is described, wherein WRF provided temperature...

  9. Building optimal regression tree by ant colony system-genetic algorithm: Application to modeling of melting points

    Energy Technology Data Exchange (ETDEWEB)

    Hemmateenejad, Bahram, E-mail: hemmatb@sums.ac.ir [Department of Chemistry, Shiraz University, Shiraz (Iran, Islamic Republic of); Medicinal and Natural Products Chemistry Research Center, Shiraz University of Medical Sciences, Shiraz (Iran, Islamic Republic of); Shamsipur, Mojtaba [Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Zare-Shahabadi, Vali [Young Researchers Club, Mahshahr Branch, Islamic Azad University, Mahshahr (Iran, Islamic Republic of); Akhond, Morteza [Department of Chemistry, Shiraz University, Shiraz (Iran, Islamic Republic of)

    2011-10-17

    Highlights: {yields} Ant colony systems help to build optimum classification and regression trees. {yields} Using of genetic algorithm operators in ant colony systems resulted in more appropriate models. {yields} Variable selection in each terminal node of the tree gives promising results. {yields} CART-ACS-GA could model the melting point of organic materials with prediction errors lower than previous models. - Abstract: The classification and regression trees (CART) possess the advantage of being able to handle large data sets and yield readily interpretable models. A conventional method of building a regression tree is recursive partitioning, which results in a good but not optimal tree. Ant colony system (ACS), which is a meta-heuristic algorithm and derived from the observation of real ants, can be used to overcome this problem. The purpose of this study was to explore the use of CART and its combination with ACS for modeling of melting points of a large variety of chemical compounds. Genetic algorithm (GA) operators (e.g., cross averring and mutation operators) were combined with ACS algorithm to select the best solution model. In addition, at each terminal node of the resulted tree, variable selection was done by ACS-GA algorithm to build an appropriate partial least squares (PLS) model. To test the ability of the resulted tree, a set of approximately 4173 structures and their melting points were used (3000 compounds as training set and 1173 as validation set). Further, an external test set containing of 277 drugs was used to validate the prediction ability of the tree. Comparison of the results obtained from both trees showed that the tree constructed by ACS-GA algorithm performs better than that produced by recursive partitioning procedure.

  10. Event tree analysis of accidents during transport of radioactive materials in Japan

    International Nuclear Information System (INIS)

    Watabe, N.; Shirai, K.; Noguchi, K.; Suzuki, H.; Kinehara, Y.

    1993-01-01

    The Event Tree Method is one of the Probabilistic Safety Assessment Method. It introduces the accident scenario and the results of countermeasures. Therefore, it is effective in determining latent accident scenarios in the transfer. In this report the Event Tree Method is used to study the tunnel fire and its effects are evaluated. And this is the first trail of our Probabilistic Safety Assessment. The Event Tree for determining the early conditions when a car engine catches fire in a tunnel is examined. There are fire extinguishers, tunnel equipments for fire-fighting, fire stations and the heat-resisting property of the container for protecting from the fire. The protection level against the over 800degC-30min. fire accident is 88.3 %. (J.P.N.)

  11. Rogeaulito: a world energy scenario modeling tool for transparent energy system thinking

    Directory of Open Access Journals (Sweden)

    Léo eBenichou

    2014-01-01

    Full Text Available Rogeaulito is a world energy model for scenario building developed by the European think tank The Shift Project. It’s a tool to explore world energy choices from a very long-term and systematic perspective. As a key feature and novelty it computes energy supply and demand independently from each other revealing potentially missing energy supply by 2100. It is further simple to use, didactic and open source. As such, it targets a broad user group and advocates for reproducibility and transparency in scenario modeling as well as model-based learning. Rogeaulito applies an engineering approach using disaggregated data in a spreadsheet model.

  12. Rooting phylogenetic trees under the coalescent model using site pattern probabilities.

    Science.gov (United States)

    Tian, Yuan; Kubatko, Laura

    2017-12-19

    Phylogenetic tree inference is a fundamental tool to estimate ancestor-descendant relationships among different species. In phylogenetic studies, identification of the root - the most recent common ancestor of all sampled organisms - is essential for complete understanding of the evolutionary relationships. Rooted trees benefit most downstream application of phylogenies such as species classification or study of adaptation. Often, trees can be rooted by using outgroups, which are species that are known to be more distantly related to the sampled organisms than any other species in the phylogeny. However, outgroups are not always available in evolutionary research. In this study, we develop a new method for rooting species tree under the coalescent model, by developing a series of hypothesis tests for rooting quartet phylogenies using site pattern probabilities. The power of this method is examined by simulation studies and by application to an empirical North American rattlesnake data set. The method shows high accuracy across the simulation conditions considered, and performs well for the rattlesnake data. Thus, it provides a computationally efficient way to accurately root species-level phylogenies that incorporates the coalescent process. The method is robust to variation in substitution model, but is sensitive to the assumption of a molecular clock. Our study establishes a computationally practical method for rooting species trees that is more efficient than traditional methods. The method will benefit numerous evolutionary studies that require rooting a phylogenetic tree without having to specify outgroups.

  13. Categorizing ideas about trees: a tree of trees.

    Science.gov (United States)

    Fisler, Marie; Lecointre, Guillaume

    2013-01-01

    The aim of this study is to explore whether matrices and MP trees used to produce systematic categories of organisms could be useful to produce categories of ideas in history of science. We study the history of the use of trees in systematics to represent the diversity of life from 1766 to 1991. We apply to those ideas a method inspired from coding homologous parts of organisms. We discretize conceptual parts of ideas, writings and drawings about trees contained in 41 main writings; we detect shared parts among authors and code them into a 91-characters matrix and use a tree representation to show who shares what with whom. In other words, we propose a hierarchical representation of the shared ideas about trees among authors: this produces a "tree of trees." Then, we categorize schools of tree-representations. Classical schools like "cladists" and "pheneticists" are recovered but others are not: "gradists" are separated into two blocks, one of them being called here "grade theoreticians." We propose new interesting categories like the "buffonian school," the "metaphoricians," and those using "strictly genealogical classifications." We consider that networks are not useful to represent shared ideas at the present step of the study. A cladogram is made for showing who is sharing what with whom, but also heterobathmy and homoplasy of characters. The present cladogram is not modelling processes of transmission of ideas about trees, and here it is mostly used to test for proximity of ideas of the same age and for categorization.

  14. Land-use change outweighs projected effects of changing rainfall on tree cover in sub-Saharan Africa.

    Science.gov (United States)

    Aleman, Julie C; Blarquez, Olivier; Staver, Carla A

    2016-09-01

    Global change will likely affect savanna and forest structure and distributions, with implications for diversity within both biomes. Few studies have examined the impacts of both expected precipitation and land use changes on vegetation structure in the future, despite their likely severity. Here, we modeled tree cover in sub-Saharan Africa, as a proxy for vegetation structure and land cover change, using climatic, edaphic, and anthropic data (R(2)  = 0.97). Projected tree cover for the year 2070, simulated using scenarios that include climate and land use projections, generally decreased, both in forest and savanna, although the directionality of changes varied locally. The main driver of tree cover changes was land use change; the effects of precipitation change were minor by comparison. Interestingly, carbon emissions mitigation via increasing biofuels production resulted in decreases in tree cover, more severe than scenarios with more intense precipitation change, especially within savannas. Evaluation of tree cover change against protected area extent at the WWF Ecoregion scale suggested areas of high biodiversity and ecosystem services concern. Those forests most vulnerable to large decreases in tree cover were also highly protected, potentially buffering the effects of global change. Meanwhile, savannas, especially where they immediately bordered forests (e.g. West and Central Africa), were characterized by a dearth of protected areas, making them highly vulnerable. Savanna must become an explicit policy priority in the face of climate and land use change if conservation and livelihoods are to remain viable into the next century. © 2016 John Wiley & Sons Ltd.

  15. The relative contributions of disease and insects in the decline of a long-lived tree: a stochastic demographic model of whitebark pine (Pinus albicaulis)

    Science.gov (United States)

    Jules, Erik S; Jackson, Jenell I.; van Mantgem, Phillip J.; Beck, Jennifer S.; Murray, Michael P.; Sahara, E. April

    2016-01-01

    Pathogens and insect pests have become increasingly important drivers of tree mortality in forested ecosystems. Unfortunately, understanding the relative contributions of multiple mortality agents to the population decline of trees is difficult, because it requires frequent measures of tree survival, growth, and recruitment, as well as the incidence of mortality agents. We present a population model of whitebark pine (Pinus albicaulis), a high-elevation tree undergoing rapid decline in western North America. The loss of whitebark pine is thought to be primarily due to an invasive pathogen (white pine blister rust; Cronartium ribicola) and a native insect (mountain pine beetle; Dendroctonus ponderosae). We utilized seven plots in Crater Lake National Park (Oregon, USA) where 1220 trees were surveyed for health and the presence of blister rust and beetle activity annually from 2003–2014, except 2008. We constructed size-based projection matrices for nine years and calculated the deterministic growth rate (λ) using an average matrix and the stochastic growth rate (λs) by simulation for whitebark pine in our study population. We then assessed the roles of blister rust and beetles by calculating λ and λsusing matrices in which we removed trees with blister rust and, separately, trees with beetles. We also conducted life-table response experiments (LTRE) to determine which demographic changes contributed most to differences in λ between ambient conditions and the two other scenarios. The model suggests that whitebark pine in our plots are currently declining 1.1% per year (λ = 0.9888, λs = 0.9899). Removing blister rust from the models resulted in almost no increase in growth (λ = 0.9916, λs = 0.9930), while removing beetles resulted in a larger increase in growth (λ = 1.0028, λs = 1.0045). The LTRE demonstrated that reductions in stasis of the three largest size classes due to beetles contributed most to the smaller λ in the ambient condition

  16. SWAT meta-modeling as support of the management scenario analysis in large watersheds.

    Science.gov (United States)

    Azzellino, A; Çevirgen, S; Giupponi, C; Parati, P; Ragusa, F; Salvetti, R

    2015-01-01

    In the last two decades, numerous models and modeling techniques have been developed to simulate nonpoint source pollution effects. Most models simulate the hydrological, chemical, and physical processes involved in the entrainment and transport of sediment, nutrients, and pesticides. Very often these models require a distributed modeling approach and are limited in scope by the requirement of homogeneity and by the need to manipulate extensive data sets. Physically based models are extensively used in this field as a decision support for managing the nonpoint source emissions. A common characteristic of this type of model is a demanding input of several state variables that makes the calibration and effort-costing in implementing any simulation scenario more difficult. In this study the USDA Soil and Water Assessment Tool (SWAT) was used to model the Venice Lagoon Watershed (VLW), Northern Italy. A Multi-Layer Perceptron (MLP) network was trained on SWAT simulations and used as a meta-model for scenario analysis. The MLP meta-model was successfully trained and showed an overall accuracy higher than 70% both on the training and on the evaluation set, allowing a significant simplification in conducting scenario analysis.

  17. Surface-based geometric modelling using teaching trees for advanced robots

    International Nuclear Information System (INIS)

    Nakamura, Akira; Ogasawara, Tsukasa; Tsukune, Hideo; Oshima, Masaki

    2000-01-01

    Geometric modelling of the environment is important in robot motion planning. Generally, shapes can be stored in a data base, so the elements that need to be decided are positions and orientations. In this paper, surface-based geometric modelling using a teaching tree is proposed. In this modelling, combinations of surfaces are considered in order to decide positions and orientations of objects. The combinations are represented by a depth-first tree, which makes it easy for the operator to select one combination out of several. This method is effective not only in the case when perfect data can be obtained, but also when conditions for measurement of three-dimensional data are unfavorable, which often occur in the environment of a working robot. (author)

  18. Decision- rather than scenario-centred downscaling: Towards smarter use of climate model outputs

    Science.gov (United States)

    Wilby, Robert L.

    2013-04-01

    Climate model output has been used for hydrological impact assessments for at least 25 years. Scenario-led methods raise awareness about risks posed by climate variability and change to the security of supplies, performance of water infrastructure, and health of freshwater ecosystems. However, it is less clear how these analyses translate into actionable information for adaptation. One reason is that scenario-led methods typically yield very large uncertainty bounds in projected impacts at regional and river catchment scales. Consequently, there is growing interest in vulnerability-based frameworks and strategies for employing climate model output in decision-making contexts. This talk begins by summarising contrasting perspectives on climate models and principles for testing their utility for water sector applications. Using selected examples it is then shown how water resource systems may be adapted with varying levels of reliance on climate model information. These approaches include the conventional scenario-led risk assessment, scenario-neutral strategies, safety margins and sensitivity testing, and adaptive management of water systems. The strengths and weaknesses of each approach are outlined and linked to selected water management activities. These cases show that much progress can be made in managing water systems without dependence on climate models. Low-regret measures such as improved forecasting, better inter-agency co-operation, and contingency planning, yield benefits regardless of the climate outlook. Nonetheless, climate model scenarios are useful for evaluating adaptation portfolios, identifying system thresholds and fixing weak links, exploring the timing of investments, improving operating rules, or developing smarter licensing regimes. The most problematic application remains the climate change safety margin because of the very low confidence in extreme precipitation and river flows generated by climate models. In such cases, it is necessary to

  19. Identifying the rooted species tree from the distribution of unrooted gene trees under the coalescent.

    Science.gov (United States)

    Allman, Elizabeth S; Degnan, James H; Rhodes, John A

    2011-06-01

    Gene trees are evolutionary trees representing the ancestry of genes sampled from multiple populations. Species trees represent populations of individuals-each with many genes-splitting into new populations or species. The coalescent process, which models ancestry of gene copies within populations, is often used to model the probability distribution of gene trees given a fixed species tree. This multispecies coalescent model provides a framework for phylogeneticists to infer species trees from gene trees using maximum likelihood or Bayesian approaches. Because the coalescent models a branching process over time, all trees are typically assumed to be rooted in this setting. Often, however, gene trees inferred by traditional phylogenetic methods are unrooted. We investigate probabilities of unrooted gene trees under the multispecies coalescent model. We show that when there are four species with one gene sampled per species, the distribution of unrooted gene tree topologies identifies the unrooted species tree topology and some, but not all, information in the species tree edges (branch lengths). The location of the root on the species tree is not identifiable in this situation. However, for 5 or more species with one gene sampled per species, we show that the distribution of unrooted gene tree topologies identifies the rooted species tree topology and all its internal branch lengths. The length of any pendant branch leading to a leaf of the species tree is also identifiable for any species from which more than one gene is sampled.

  20. Land use change modeling through scenario-based cellular automata Markov: improving spatial forecasting.

    Science.gov (United States)

    Jahanishakib, Fatemeh; Mirkarimi, Seyed Hamed; Salmanmahiny, Abdolrassoul; Poodat, Fatemeh

    2018-05-08

    Efficient land use management requires awareness of past changes, present actions, and plans for future developments. Part of these requirements is achieved using scenarios that describe a future situation and the course of changes. This research aims to link scenario results with spatially explicit and quantitative forecasting of land use development. To develop land use scenarios, SMIC PROB-EXPERT and MORPHOL methods were used. It revealed eight scenarios as the most probable. To apply the scenarios, we considered population growth rate and used a cellular automata-Markov chain (CA-MC) model to implement the quantified changes described by each scenario. For each scenario, a set of landscape metrics was used to assess the ecological integrity of land use classes in terms of fragmentation and structural connectivity. The approach enabled us to develop spatial scenarios of land use change and detect their differences for choosing the most integrated landscape pattern in terms of landscape metrics. Finally, the comparison between paired forecasted scenarios based on landscape metrics indicates that scenarios 1-1, 2-2, 3-2, and 4-1 have a more suitable integrity. The proposed methodology for developing spatial scenarios helps executive managers to create scenarios with many repetitions and customize spatial patterns in real world applications and policies.

  1. Modeling Answer Change Behavior: An Application of a Generalized Item Response Tree Model

    Science.gov (United States)

    Jeon, Minjeong; De Boeck, Paul; van der Linden, Wim

    2017-01-01

    We present a novel application of a generalized item response tree model to investigate test takers' answer change behavior. The model allows us to simultaneously model the observed patterns of the initial and final responses after an answer change as a function of a set of latent traits and item parameters. The proposed application is illustrated…

  2. Parallel family trees for transfer matrices in the Potts model

    Science.gov (United States)

    Navarro, Cristobal A.; Canfora, Fabrizio; Hitschfeld, Nancy; Navarro, Gonzalo

    2015-02-01

    The computational cost of transfer matrix methods for the Potts model is related to the question in how many ways can two layers of a lattice be connected? Answering the question leads to the generation of a combinatorial set of lattice configurations. This set defines the configuration space of the problem, and the smaller it is, the faster the transfer matrix can be computed. The configuration space of generic (q , v) transfer matrix methods for strips is in the order of the Catalan numbers, which grows asymptotically as O(4m) where m is the width of the strip. Other transfer matrix methods with a smaller configuration space indeed exist but they make assumptions on the temperature, number of spin states, or restrict the structure of the lattice. In this paper we propose a parallel algorithm that uses a sub-Catalan configuration space of O(3m) to build the generic (q , v) transfer matrix in a compressed form. The improvement is achieved by grouping the original set of Catalan configurations into a forest of family trees, in such a way that the solution to the problem is now computed by solving the root node of each family. As a result, the algorithm becomes exponentially faster than the Catalan approach while still highly parallel. The resulting matrix is stored in a compressed form using O(3m ×4m) of space, making numerical evaluation and decompression to be faster than evaluating the matrix in its O(4m ×4m) uncompressed form. Experimental results for different sizes of strip lattices show that the parallel family trees (PFT) strategy indeed runs exponentially faster than the Catalan Parallel Method (CPM), especially when dealing with dense transfer matrices. In terms of parallel performance, we report strong-scaling speedups of up to 5.7 × when running on an 8-core shared memory machine and 28 × for a 32-core cluster. The best balance of speedup and efficiency for the multi-core machine was achieved when using p = 4 processors, while for the cluster

  3. A Two-Account Life Insurance Model for Scenario-Based Valuation Including Event Risk

    Directory of Open Access Journals (Sweden)

    Ninna Reitzel Jensen

    2015-06-01

    Full Text Available Using a two-account model with event risk, we model life insurance contracts taking into account both guaranteed and non-guaranteed payments in participating life insurance as well as in unit-linked insurance. Here, event risk is used as a generic term for life insurance events, such as death, disability, etc. In our treatment of participating life insurance, we have special focus on the bonus schemes “consolidation” and “additional benefits”, and one goal is to formalize how these work and interact. Another goal is to describe similarities and differences between participating life insurance and unit-linked insurance. By use of a two-account model, we are able to illustrate general concepts without making the model too abstract. To allow for complicated financial markets without dramatically increasing the mathematical complexity, we focus on economic scenarios. We illustrate the use of our model by conducting scenario analysis based on Monte Carlo simulation, but the model applies to scenarios in general and to worst-case and best-estimate scenarios in particular. In addition to easy computations, our model offers a common framework for the valuation of life insurance payments across product types. This enables comparison of participating life insurance products and unit-linked insurance products, thus building a bridge between the two different ways of formalizing life insurance products. Finally, our model distinguishes itself from the existing literature by taking into account the Markov model for the state of the policyholder and, hereby, facilitating event risk.

  4. Incorporating additional tree and environmental variables in a lodgepole pine stem profile model

    Science.gov (United States)

    John C. Byrne

    1993-01-01

    A new variable-form segmented stem profile model is developed for lodgepole pine (Pinus contorta) trees from the northern Rocky Mountains of the United States. I improved estimates of stem diameter by predicting two of the model coefficients with linear equations using a measure of tree form, defined as a ratio of dbh and total height. Additional improvements were...

  5. How will climate change affect the potential distribution of Eurasian Tree Sparrows Passer montanus in North America?

    Science.gov (United States)

    Graham, Jim; Jarnevich, Catherine; Young, Nick; Newman, Greg; Stohlgren, Thomas

    2011-01-01

    Habitat suitability models have been used to predict the present and future potential distribution of a variety of species. Eurasian tree sparrows Passer montanus, native to Eurasia, have established populations in other parts of the world. In North America, their current distribution is limited to a relatively small region around its original introduction to St. Louis, Missouri. We combined data from the Global Biodiversity Information Facility with current and future climate data to create habitat suitability models using Maxent for this species. Under projected climate change scenarios, our models show that the distribution and range of the Eurasian tree sparrow could increase as far as the Pacific Northwest and Newfoundland. This is potentially important information for prioritizing the management and control of this non-native species.

  6. Modeling stem increment in individual Pinus occidentalis Sw. trees in La Sierra, Dominican Republic

    Energy Technology Data Exchange (ETDEWEB)

    Bueno, S.; Bevilacqua, E.

    2010-07-01

    One of the most common and important tree characteristics used in forest management decision-making is tree diameter-at-breast height (DBH). This paper presents results on an evaluation of two growth functions developed to model stem diameter increases in individual Pinus occidentalis Sw. trees in La Sierra, Dominican Republic. The first model was developed in order to predict future DBH (FDM) at different intervals of time and the other for predicting growth, that is, periodic annual diameter increment (PADIM). Each model employed two statistical techniques for fitting model parameters: stepwise ordinary least squares (OLS) regression, and mixed models. The two statistical approaches varied in how they accounted for the repeated measurements on individual trees over time, affecting standard error estimates and statistical inference of model parameters. Each approach was evaluated based on six goodness of- fit statistics, using both calibration and validation data sets. The objectives were 1) to determine the best model for predicting future tree DBH; 2) to determine the best model for predicting periodic annual diameter increment, both models using tree size, age, site index and different indices of competitive status; and 3) compare which of these two modeling approaches predicts better the future DBH. OLS provided a better fit for both of the growth functions, especially in regards to bias. Both models showed advantages and disadvantages when they were used to predict growth and future diameter. For the prediction of future diameter with FDM, accuracy of predictions were within one centimeter for a five-year projection interval. The PADIM presented negligible bias in estimating future diameter, although there was a small increase in bias as time of prediction increased. As expected, each model was the best in estimating the response variable it was developed for.. However, a closer examination of the distribution of errors showed a slight advantage of the FDM

  7. Intercomparison of hydrological model structures and calibration approaches in climate scenario impact projections

    Science.gov (United States)

    Vansteenkiste, Thomas; Tavakoli, Mohsen; Ntegeka, Victor; De Smedt, Florimond; Batelaan, Okke; Pereira, Fernando; Willems, Patrick

    2014-11-01

    The objective of this paper is to investigate the effects of hydrological model structure and calibration on climate change impact results in hydrology. The uncertainty in the hydrological impact results is assessed by the relative change in runoff volumes and peak and low flow extremes from historical and future climate conditions. The effect of the hydrological model structure is examined through the use of five hydrological models with different spatial resolutions and process descriptions. These were applied to a medium sized catchment in Belgium. The models vary from the lumped conceptual NAM, PDM and VHM models over the intermediate detailed and distributed WetSpa model to the fully distributed MIKE SHE model. The latter model accounts for the 3D groundwater processes and interacts bi-directionally with a full hydrodynamic MIKE 11 river model. After careful and manual calibration of these models, accounting for the accuracy of the peak and low flow extremes and runoff subflows, and the changes in these extremes for changing rainfall conditions, the five models respond in a similar way to the climate scenarios over Belgium. Future projections on peak flows are highly uncertain with expected increases as well as decreases depending on the climate scenario. The projections on future low flows are more uniform; low flows decrease (up to 60%) for all models and for all climate scenarios. However, the uncertainties in the impact projections are high, mainly in the dry season. With respect to the model structural uncertainty, the PDM model simulates significantly higher runoff peak flows under future wet scenarios, which is explained by its specific model structure. For the low flow extremes, the MIKE SHE model projects significantly lower low flows in dry scenario conditions in comparison to the other models, probably due to its large difference in process descriptions for the groundwater component, the groundwater-river interactions. The effect of the model

  8. Complementary models of tree species-soil relationships in old-growth temperate forests

    Science.gov (United States)

    Cross, Alison; Perakis, Steven S.

    2011-01-01

    Ecosystem level studies identify plant soil feed backs as important controls on soil nutrient availability,particularly for nitrogen and phosphorus. Although site and species specific studies of tree species soil relationships are relatively common,comparatively fewer studies consider multiple coexisting speciesin old-growth forests across a range of sites that vary underlying soil fertility. We characterized patterns in forest floor and mineral soil nutrients associated with four common tree species across eight undisturbed old-growth forests in Oregon, USA, and used two complementary conceptual models to assess tree species soil relationships. Plant soil feedbacks that could reinforce sitelevel differences in nutrient availability were assessed using the context dependent relationships model, where by relative species based differences in each soil nutrient divergedorconvergedas nutrient status changed across sites. Tree species soil relationships that did not reflect strong feedbacks were evaluated using a site independent relationships model, where by forest floor and surface mineral soil nutrient tools differed consistently by tree species across sites,without variation in deeper mineral soils. We found that theorganically cycled elements carbon, nitrogen, and phosphorus exhibited context-dependent differences among species in both forest floor and mineral soil, and most of ten followed adivergence model,where by species differences were greatest at high-nutrient sites. These patterns are consistent with the oryemphasizing biotic control of these elements through plant soil feedback mechanisms. Site independent species differences were strongest for pool so if the weather able cations calcium, magnesium, potassium,as well as phosphorus, in mineral soils. Site independent species differences in forest floor nutrients we reattributable too nespecies that displayed significant greater forest floor mass accumulation. Our finding confirmed that site-independent and

  9. Using Scenario-based Business Modelling to Explore the 5G Telecommunication Market

    DEFF Research Database (Denmark)

    Moqaddamerad, Sara; Ahokangas, Petri; Matinmikko, Marja

    2017-01-01

    Innovative technologies often alter established value chains and make traditional strategic planning methods inadequate. In this paper, we present the use of scenario-based business modelling to explore the market for the fifth generation mobile communication networks (5G). We discuss four...... scenarios that have been developed in a collaborative effort among different actors in the market. We then describe the approach to build business models and discuss lessons learned and benefits from the novel approach. This approach complements traditional techniques through providing a powerful platform...

  10. Model checking coalitional games in shortage resource scenarios

    Directory of Open Access Journals (Sweden)

    Dario Della Monica

    2013-07-01

    Full Text Available Verification of multi-agents systems (MAS has been recently studied taking into account the need of expressing resource bounds. Several logics for specifying properties of MAS have been presented in quite a variety of scenarios with bounded resources. In this paper, we study a different formalism, called Priced Resource-Bounded Alternating-time Temporal Logic (PRBATL, whose main novelty consists in moving the notion of resources from a syntactic level (part of the formula to a semantic one (part of the model. This allows us to track the evolution of the resource availability along the computations and provides us with a formalisms capable to model a number of real-world scenarios. Two relevant aspects are the notion of global availability of the resources on the market, that are shared by the agents, and the notion of price of resources, depending on their availability. In a previous work of ours, an initial step towards this new formalism was introduced, along with an EXPTIME algorithm for the model checking problem. In this paper we better analyze the features of the proposed formalism, also in comparison with previous approaches. The main technical contribution is the proof of the EXPTIME-hardness of the the model checking problem for PRBATL, based on a reduction from the acceptance problem for Linearly-Bounded Alternating Turing Machines. In particular, since the problem has multiple parameters, we show two fixed-parameter reductions.

  11. Modeling pollinator community response to contrasting bioenergy scenarios.

    Directory of Open Access Journals (Sweden)

    Ashley B Bennett

    Full Text Available In the United States, policy initiatives aimed at increasing sources of renewable energy are advancing bioenergy production, especially in the Midwest region, where agricultural landscapes dominate. While policy directives are focused on renewable fuel production, biodiversity and ecosystem services will be impacted by the land-use changes required to meet production targets. Using data from field observations, we developed empirical models for predicting abundance, diversity, and community composition of flower-visiting bees based on land cover. We used these models to explore how bees might respond under two contrasting bioenergy scenarios: annual bioenergy crop production and perennial grassland bioenergy production. In the two scenarios, 600,000 ha of marginal annual crop land or marginal grassland were converted to perennial grassland or annual row crop bioenergy production, respectively. Model projections indicate that expansion of annual bioenergy crop production at this scale will reduce bee abundance by 0 to 71%, and bee diversity by 0 to 28%, depending on location. In contrast, converting annual crops on marginal soil to perennial grasslands could increase bee abundance from 0 to 600% and increase bee diversity between 0 and 53%. Our analysis of bee community composition suggested a similar pattern, with bee communities becoming less diverse under annual bioenergy crop production, whereas bee composition transitioned towards a more diverse community dominated by wild bees under perennial bioenergy crop production. Models, like those employed here, suggest that bioenergy policies have important consequences for pollinator conservation.

  12. The algebra of the general Markov model on phylogenetic trees and networks.

    Science.gov (United States)

    Sumner, J G; Holland, B R; Jarvis, P D

    2012-04-01

    It is known that the Kimura 3ST model of sequence evolution on phylogenetic trees can be extended quite naturally to arbitrary split systems. However, this extension relies heavily on mathematical peculiarities of the associated Hadamard transformation, and providing an analogous augmentation of the general Markov model has thus far been elusive. In this paper, we rectify this shortcoming by showing how to extend the general Markov model on trees to include incompatible edges; and even further to more general network models. This is achieved by exploring the algebra of the generators of the continuous-time Markov chain together with the “splitting” operator that generates the branching process on phylogenetic trees. For simplicity, we proceed by discussing the two state case and then show that our results are easily extended to more states with little complication. Intriguingly, upon restriction of the two state general Markov model to the parameter space of the binary symmetric model, our extension is indistinguishable from the Hadamard approach only on trees; as soon as any incompatible splits are introduced the two approaches give rise to differing probability distributions with disparate structure. Through exploration of a simple example, we give an argument that our extension to more general networks has desirable properties that the previous approaches do not share. In particular, our construction allows for convergent evolution of previously divergent lineages; a property that is of significant interest for biological applications.

  13. Distance-independent individual tree diameter-increment model for Thuya [Tetraclinis articulata (VAHL. MAST.] stands in Tunisia

    Directory of Open Access Journals (Sweden)

    T. Sghaier

    2013-12-01

    Full Text Available Aim of study: The aim of the work was to develop an individual tree diameter-increment model for Thuya (Tetraclinis articulata in Tunisia.Area of study: The natural Tetraclinis articulata stands at Jbel Lattrech in north-eastern of Tunisia.Material and methods:  Data came from 200 trees located in 50 sample plots. The diameter at age t and the diameter increment for the last five years obtained from cores taken at breast height were measured for each tree. Four difference equations derived from the base functions of Richards, Lundqvist, Hossfeld IV and Weibull were tested using the age-independent formulations of the growth functions. Both numerical and graphical analyses were used to evaluate the performance of the candidate models.Main results: Based on the analysis, the age-independent difference equation derived from the base function Richards model was selected. Two of the three parameters (growth rate and shape parameter of the retained model were related to site quality, represented by a Growth Index, stand density and the basal area in larger trees divided by diameter of the subject tree expressing the inter-tree competition.Research highlights: The proposed model can be useful for predicting the diameter growth of Tetraclinis articulata in Tunisia when age is not available or for trees growing in uneven-aged stands.Keywords: Age-independent growth model; difference equations; Tetraclinis articulata; Tunisia.

  14. Tree Colors: Color Schemes for Tree-Structured Data.

    Science.gov (United States)

    Tennekes, Martijn; de Jonge, Edwin

    2014-12-01

    We present a method to map tree structures to colors from the Hue-Chroma-Luminance color model, which is known for its well balanced perceptual properties. The Tree Colors method can be tuned with several parameters, whose effect on the resulting color schemes is discussed in detail. We provide a free and open source implementation with sensible parameter defaults. Categorical data are very common in statistical graphics, and often these categories form a classification tree. We evaluate applying Tree Colors to tree structured data with a survey on a large group of users from a national statistical institute. Our user study suggests that Tree Colors are useful, not only for improving node-link diagrams, but also for unveiling tree structure in non-hierarchical visualizations.

  15. Using decision tree induction systems for modeling space-time behavior

    NARCIS (Netherlands)

    Arentze, T.A.; Hofman, F.; Mourik, van H.; Timmermans, H.J.P.; Wets, G.

    2000-01-01

    Discrete choice models are commonly used to predict individuals' activity and travel choices either separately or simultaneously in activity scheduling models. This paper investigates the possibilities of decision tree induction systems as an alternative approach. The ability of decision frees to

  16. European Climate - Energy Security Nexus. A model based scenario analysis

    International Nuclear Information System (INIS)

    Criqui, Patrick; Mima, Silvana

    2011-01-01

    In this research, we have provided an overview of the climate-security nexus in the European sector through a model based scenario analysis with POLES model. The analysis underline that under stringent climate policies, Europe take advantage of a double dividend in its capacity to develop a new cleaner energy model and in lower vulnerability to potential shocks on the international energy markets. (authors)

  17. Modeling the Greek energy system: Scenarios of clean energy use and their implications

    International Nuclear Information System (INIS)

    Roinioti, Argiro; Koroneos, Christopher; Wangensteen, Ivar

    2012-01-01

    The Greek energy system is one of the most carbon intensive energy systems in Europe. Hydrocarbons and solid fuels (lignite) cover over 80% of the final energy demand. The main objective of this work is to build energy scenarios for the future – with a focus on the electricity production system – and explore how these scenarios are reflected in economic, environmental terms and in terms of energy efficiency. The main tool which is used in the scenario analysis is LEAP (Long range Energy Alternatives Planning System). The scenarios are essentially the result of developing “storylines” driven by the uncertainties which cannot be controlled by the analysts or decision makers, and technical and non-technical options the analyst or decision maker may choose from. A set of uncertainties is considered as a possible future or storyline, and one or more options can be selected as a possible strategy. The combination of a storyline and a specific strategy gives a scenario. The main uncertainties for the Greek energy system are identified and various technical options are explored. Rather than using a model which leads to optimum strategies from a set of alternatives, the model in use will apply different strategies. - Highlights: ► A demand-driven approach was used to build energy scenarios for the Greek interconnected system. ► Each Scenario consists of a possible future and a strategy. ► High RES penetration will decrease CO 2 emissions but it will also increase capital cost. ► Carbon intensity is reduced in all the scenarios.

  18. Truth-telling and Nash equilibria in minimum cost spanning tree models

    DEFF Research Database (Denmark)

    Hougaard, Jens Leth; Tvede, Mich

    2012-01-01

    In this paper we consider the minimum cost spanning tree model. We assume that a central planner aims at implementing a minimum cost spanning tree not knowing the true link costs. The central planner sets up a game where agents announce link costs, a tree is chosen and costs are allocated according...... to the rules of the game. We characterize ways of allocating costs such that true announcements constitute Nash equilibria both in case of full and incomplete information. In particular, we find that the Shapley rule based on the irreducible cost matrix is consistent with truthful announcements while a series...

  19. Helping Moroccan women preserve the argan tree at the gateway to ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2010-11-01

    Nov 1, 2010 ... ... Charrouf of the Faculté des sciences at the Université Mohammed V of Rabat, and Professor ... Therefore, the project aims not only to help prevent further ... the development of argan tree management scenarios; the selection of trees ... on the French networks (France 2 and FR3), and on Radio-Canada.

  20. Looking Forward: Using Scenario Modeling to Support Regional Land Use Planning in Northern Yukon, Canada

    Directory of Open Access Journals (Sweden)

    Shawn R. Francis

    2011-12-01

    We describe how the ALCES® landscape cumulative effects simulation model was used to explore possible outcomes of an oil and gas scenario in the Eagle Plain basin of the North Yukon Planning Region of Yukon Territory, Canada. Scenario modeling was conducted to facilitate informed discussion about key land use issues and practices, potential levels of landscape change, and possible socioeconomic benefits and environmental impacts. Modeling results supported the sustainable development and cumulative effects management recommendations of the North Yukon Regional Land Use Plan. Land use scenario modeling, as applied in this project, was found to be an effective approach for establishing sustainable development guidelines through a regional planning process.

  1. A Model for Generating Multi-hazard Scenarios

    Science.gov (United States)

    Lo Jacomo, A.; Han, D.; Champneys, A.

    2017-12-01

    Communities in mountain areas are often subject to risk from multiple hazards, such as earthquakes, landslides, and floods. Each hazard has its own different rate of onset, duration, and return period. Multiple hazards tend to complicate the combined risk due to their interactions. Prioritising interventions for minimising risk in this context is challenging. We developed a probabilistic multi-hazard model to help inform decision making in multi-hazard areas. The model is applied to a case study region in the Sichuan province in China, using information from satellite imagery and in-situ data. The model is not intended as a predictive model, but rather as a tool which takes stakeholder input and can be used to explore plausible hazard scenarios over time. By using a Monte Carlo framework and varrying uncertain parameters for each of the hazards, the model can be used to explore the effect of different mitigation interventions aimed at reducing the disaster risk within an uncertain hazard context.

  2. A conceptual approach to approximate tree root architecture in infinite slope models

    Science.gov (United States)

    Schmaltz, Elmar; Glade, Thomas

    2016-04-01

    Vegetation-related properties - particularly tree root distribution and coherent hydrologic and mechanical effects on the underlying soil mantle - are commonly not considered in infinite slope models. Indeed, from a geotechnical point of view, these effects appear to be difficult to be reproduced reliably in a physically-based modelling approach. The growth of a tree and the expansion of its root architecture are directly connected with both intrinsic properties such as species and age, and extrinsic factors like topography, availability of nutrients, climate and soil type. These parameters control four main issues of the tree root architecture: 1) Type of rooting; 2) maximum growing distance to the tree stem (radius r); 3) maximum growing depth (height h); and 4) potential deformation of the root system. Geometric solids are able to approximate the distribution of a tree root system. The objective of this paper is to investigate whether it is possible to implement root systems and the connected hydrological and mechanical attributes sufficiently in a 3-dimensional slope stability model. Hereby, a spatio-dynamic vegetation module should cope with the demands of performance, computation time and significance. However, in this presentation, we focus only on the distribution of roots. The assumption is that the horizontal root distribution around a tree stem on a 2-dimensional plane can be described by a circle with the stem located at the centroid and a distinct radius r that is dependent on age and species. We classified three main types of tree root systems and reproduced the species-age-related root distribution with three respective mathematical solids in a synthetic 3-dimensional hillslope ambience. Thus, two solids in an Euclidian space were distinguished to represent the three root systems: i) cylinders with radius r and height h, whilst the dimension of latter defines the shape of a taproot-system or a shallow-root-system respectively; ii) elliptic

  3. Dark matter scenarios in a constrained model with Dirac gauginos

    CERN Document Server

    Goodsell, Mark D.; Müller, Tobias; Porod, Werner; Staub, Florian

    2015-01-01

    We perform the first analysis of Dark Matter scenarios in a constrained model with Dirac Gauginos. The model under investigation is the Constrained Minimal Dirac Gaugino Supersymmetric Standard model (CMDGSSM) where the Majorana mass terms of gauginos vanish. However, $R$-symmetry is broken in the Higgs sector by an explicit and/or effective $B_\\mu$-term. This causes a mass splitting between Dirac states in the fermion sector and the neutralinos, which provide the dark matter candidate, become pseudo-Dirac states. We discuss two scenarios: the universal case with all scalar masses unified at the GUT scale, and the case with non-universal Higgs soft-terms. We identify different regions in the parameter space which fullfil all constraints from the dark matter abundance, the limits from SUSY and direct dark matter searches and the Higgs mass. Most of these points can be tested with the next generation of direct dark matter detection experiments.

  4. Climate change effects on the geographic distribution of specialist tree species of the Brazilian tropical dry forests.

    Science.gov (United States)

    Rodrigues, P M S; Silva, J O; Eisenlohr, P V; Schaefer, C E G R

    2015-08-01

    The aim of this study was to evaluate the ecological niche models (ENMs) for three specialist trees (Anadenanthera colubrina, Aspidosperma pyrifolium and Myracrodruon urundeuva) in seasonally dry tropical forests (SDTFs) in Brazil, considering present and future pessimist scenarios (2080) of climate change. These three species exhibit typical deciduousness and are widely distributed by SDTF in South America, being important in studies of the historical and evolutionary processes experienced by this ecosystem. The modeling of the potential geographic distribution of species was done by the method of maximum entropy (Maxent).We verified a general expansion of suitable areas for occurrence of the three species in future (c.a., 18%), although there was reduction of areas with high environmental suitability in Caatinga region. Precipitation of wettest quarter and temperature seasonality were the predictor variables that most contributed to our models. Climatic changes can provide more severe and longer dry season with increasing temperature and tree mortality in tropics. On this scenario, areas currently occupied by rainforest and savannas could become more suitable for occurrence of the SDTF specialist trees, whereas regions occupied by Caatinga could not support the future level of unsustainable (e.g., aridity). Long-term multidisciplinary studies are necessary to make reliable predictions of the plant's adaptation strategies and responses to climate changes in dry forest at community level. Based on the high deforestation rate, endemism and threat, public policies to minimize the effects of climate change on the biodiversity found within SDTFs must be undertaken rapidly.

  5. Comparison of tree types of models for the prediction of final academic achievement

    Directory of Open Access Journals (Sweden)

    Silvana Gasar

    2002-12-01

    Full Text Available For efficient prevention of inappropriate secondary school choices and by that academic failure, school counselors need a tool for the prediction of individual pupil's final academic achievements. Using data mining techniques on pupils' data base and expert modeling, we developed several models for the prediction of final academic achievement in an individual high school educational program. For data mining, we used statistical analyses, clustering and two machine learning methods: developing classification decision trees and hierarchical decision models. Using an expert system shell DEX, an expert system, based on a hierarchical multi-attribute decision model, was developed manually. All the models were validated and evaluated from the viewpoint of their applicability. The predictive accuracy of DEX models and decision trees was equal and very satisfying, as it reached the predictive accuracy of an experienced counselor. With respect on the efficiency and difficulties in developing models, and relatively rapid changing of our education system, we propose that decision trees are used in further development of predictive models.

  6. Predictive models for radial sap flux variation in coniferous, diffuse-porous and ring-porous temperate trees.

    Science.gov (United States)

    Berdanier, Aaron B; Miniat, Chelcy F; Clark, James S

    2016-08-01

    Accurately scaling sap flux observations to tree or stand levels requires accounting for variation in sap flux between wood types and by depth into the tree. However, existing models for radial variation in axial sap flux are rarely used because they are difficult to implement, there is uncertainty about their predictive ability and calibration measurements are often unavailable. Here we compare different models with a diverse sap flux data set to test the hypotheses that radial profiles differ by wood type and tree size. We show that radial variation in sap flux is dependent on wood type but independent of tree size for a range of temperate trees. The best-fitting model predicted out-of-sample sap flux observations and independent estimates of sapwood area with small errors, suggesting robustness in the new settings. We develop a method for predicting whole-tree water use with this model and include computer code for simple implementation in other studies. Published by Oxford University Press 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  7. Simulating Crop Evapotranspiration Response under Different Planting Scenarios by Modified SWAT Model in an Irrigation District, Northwest China.

    Science.gov (United States)

    Liu, Xin; Wang, Sufen; Xue, Han; Singh, Vijay P

    2015-01-01

    Modelling crop evapotranspiration (ET) response to different planting scenarios in an irrigation district plays a significant role in optimizing crop planting patterns, resolving agricultural water scarcity and facilitating the sustainable use of water resources. In this study, the SWAT model was improved by transforming the evapotranspiration module. Then, the improved model was applied in Qingyuan Irrigation District of northwest China as a case study. Land use, soil, meteorology, irrigation scheduling and crop coefficient were considered as input data, and the irrigation district was divided into subdivisions based on the DEM and local canal systems. On the basis of model calibration and verification, the improved model showed better simulation efficiency than did the original model. Therefore, the improved model was used to simulate the crop evapotranspiration response under different planting scenarios in the irrigation district. Results indicated that crop evapotranspiration decreased by 2.94% and 6.01% under the scenarios of reducing the planting proportion of spring wheat (scenario 1) and summer maize (scenario 2) by keeping the total cultivated area unchanged. However, the total net output values presented an opposite trend under different scenarios. The values decreased by 3.28% under scenario 1, while it increased by 7.79% under scenario 2, compared with the current situation. This study presents a novel method to estimate crop evapotranspiration response under different planting scenarios using the SWAT model, and makes recommendations for strategic agricultural water management planning for the rational utilization of water resources and development of local economy by studying the impact of planting scenario changes on crop evapotranspiration and output values in the irrigation district of northwest China.

  8. Simulating Crop Evapotranspiration Response under Different Planting Scenarios by Modified SWAT Model in an Irrigation District, Northwest China.

    Directory of Open Access Journals (Sweden)

    Xin Liu

    Full Text Available Modelling crop evapotranspiration (ET response to different planting scenarios in an irrigation district plays a significant role in optimizing crop planting patterns, resolving agricultural water scarcity and facilitating the sustainable use of water resources. In this study, the SWAT model was improved by transforming the evapotranspiration module. Then, the improved model was applied in Qingyuan Irrigation District of northwest China as a case study. Land use, soil, meteorology, irrigation scheduling and crop coefficient were considered as input data, and the irrigation district was divided into subdivisions based on the DEM and local canal systems. On the basis of model calibration and verification, the improved model showed better simulation efficiency than did the original model. Therefore, the improved model was used to simulate the crop evapotranspiration response under different planting scenarios in the irrigation district. Results indicated that crop evapotranspiration decreased by 2.94% and 6.01% under the scenarios of reducing the planting proportion of spring wheat (scenario 1 and summer maize (scenario 2 by keeping the total cultivated area unchanged. However, the total net output values presented an opposite trend under different scenarios. The values decreased by 3.28% under scenario 1, while it increased by 7.79% under scenario 2, compared with the current situation. This study presents a novel method to estimate crop evapotranspiration response under different planting scenarios using the SWAT model, and makes recommendations for strategic agricultural water management planning for the rational utilization of water resources and development of local economy by studying the impact of planting scenario changes on crop evapotranspiration and output values in the irrigation district of northwest China.

  9. Stand competition determines how different tree species will cope with a warming climate.

    Directory of Open Access Journals (Sweden)

    Laura Fernández-de-Uña

    Full Text Available Plant-plant interactions influence how forests cope with climate and contribute to modulate species response to future climate scenarios. We analysed the functional relationships between growth, climate and competition for Pinus sylvestris, Quercus pyrenaica and Quercus faginea to investigate how stand competition modifies forest sensitivity to climate and simulated how annual growth rates of these species with different drought tolerance would change throughout the 21st century. Dendroecological data from stands subjected to thinning were modelled using a novel multiplicative nonlinear approach to overcome biases related to the general assumption of a linear relationship between covariates and to better mimic the biological relationships involved. Growth always decreased exponentially with increasing competition, which explained more growth variability than climate in Q. faginea and P. sylvestris. The effect of precipitation was asymptotic in all cases, while the relationship between growth and temperature reached an optimum after which growth declined with warmer temperatures. Our growth projections indicate that the less drought-tolerant P. sylvestris would be more negatively affected by climate change than the studied sub-Mediterranean oaks. Q. faginea and P. sylvestris mean growth would decrease under all the climate change scenarios assessed. However, P. sylvestris growth would decline regardless of the competition level, whereas this decrease would be offset by reduced competition in Q. faginea. Conversely, Q. pyrenaica growth would remain similar to current rates, except for the warmest scenario. Our models shed light on the nature of the species-specific interaction between climate and competition and yield important implications for management. Assuming that individual growth is directly related to tree performance, trees under low competition would better withstand the warmer conditions predicted under climate change scenarios but in

  10. A support vector machine based test for incongruence between sets of trees in tree space

    Science.gov (United States)

    2012-01-01

    Background The increased use of multi-locus data sets for phylogenetic reconstruction has increased the need to determine whether a set of gene trees significantly deviate from the phylogenetic patterns of other genes. Such unusual gene trees may have been influenced by other evolutionary processes such as selection, gene duplication, or horizontal gene transfer. Results Motivated by this problem we propose a nonparametric goodness-of-fit test for two empirical distributions of gene trees, and we developed the software GeneOut to estimate a p-value for the test. Our approach maps trees into a multi-dimensional vector space and then applies support vector machines (SVMs) to measure the separation between two sets of pre-defined trees. We use a permutation test to assess the significance of the SVM separation. To demonstrate the performance of GeneOut, we applied it to the comparison of gene trees simulated within different species trees across a range of species tree depths. Applied directly to sets of simulated gene trees with large sample sizes, GeneOut was able to detect very small differences between two set of gene trees generated under different species trees. Our statistical test can also include tree reconstruction into its test framework through a variety of phylogenetic optimality criteria. When applied to DNA sequence data simulated from different sets of gene trees, results in the form of receiver operating characteristic (ROC) curves indicated that GeneOut performed well in the detection of differences between sets of trees with different distributions in a multi-dimensional space. Furthermore, it controlled false positive and false negative rates very well, indicating a high degree of accuracy. Conclusions The non-parametric nature of our statistical test provides fast and efficient analyses, and makes it an applicable test for any scenario where evolutionary or other factors can lead to trees with different multi-dimensional distributions. The

  11. A method for generating stochastic 3D tree models with Python in Autodesk Maya

    Directory of Open Access Journals (Sweden)

    Nemanja Stojanović

    2016-12-01

    Full Text Available This paper introduces a method for generating 3D tree models using stochastic L-systems with stochastic parameters and Perlin noise. L-system is the most popular method for plant modeling and Perlin noise is extensively used for generating high detailed textures. Our approach is probabilistic. L-systems with a random choice of parameters can represent observed objects quite well and they are used for modeling and generating realistic plants. Textures and normal maps are generated with combinations of Perlin noises what make these trees completely unique. Script for generating these trees, textures and normal maps is written with Python/PyMEL/NumPy in Autodesk Maya.

  12. San Onofre/Zion auxiliary feedwater system seismic fault tree modeling

    International Nuclear Information System (INIS)

    Najafi, B.; Eide, S.

    1982-02-01

    As part of the study for the seismic evaluation of the San Onofre Unit 1 Auxiliary Feedwater System (AFWS), a fault tree model was developed capable of handling the effect of structural failure of the plant (in the event of an earthquake) on the availability of the AFWS. A compatible fault tree model was developed for the Zion Unit 1 AFWS in order to compare the results of the two systems. It was concluded that if a single failure of the San Onofre Unit 1 AFWS is to be prevented, some weight existing, locally operated locked open manual valves have to be used for isolation of a rupture in specific parts of the AFWS pipings

  13. Stem biomass and volume models of selected tropical tree species ...

    African Journals Online (AJOL)

    Stem biomass and stem volume were modelled as a function of diameter (at breast height; Dbh) and stem height (height to the crown base). Logarithmic models are presented that utilise Dbh and height data to predict tree component biomass and stem volumes. Alternative models are given that afford prediction based on ...

  14. Toward a predictive model for water and carbon fluxes of non-native trees in urban habitats

    Science.gov (United States)

    McCarthy, H. R.; Jenerette, G. D.; Pataki, D. E.

    2008-12-01

    There is considerable interest in estimating uptake of water and carbon by urban trees, in order to assess some of the major costs and benefits associated with maintaining or expanding urban tree cover. However, making large-scale estimates of water and carbon fluxes is challenging in urban ecosystems, where community composition and environmental conditions are highly altered and experimental data is sparse. This is particularly true in regions such as southern California, where few trees are native, yet many species can flourish given supplemental irrigation. In such scenarios one practical way to scale water and carbon fluxes may be to identify reliable traits which can be used to predict gas exchange when trees are transplanted to a new environment. To test this approach, leaf level gas exchange measurements were conducted on eight common urban tree species within the Los Angeles basin. The objective was to determine how well gas exchange parameters, including maximum photosynthesis and stomatal conductance, sensitivity of stomatal conductance to vapor pressure deficit (VPD), and water use efficiency (WUE), can be predicted based on the native habitat and climate (temperature and precipitation) of each study species. All of the species studied naturally occur in humid tropical or subtropical climate zones where precipitation varies widely from ~400 - 3000 mm per year. We found Jacaranda (Jacaranda chelonia) and honey locust (Gleditsia triacanthos) to have the highest photosynthesis and reference (at VPD=1 kPa) conductance, and to be most sensitive to VPD. WUE was found to be greatest in Indian laurel fig (Ficus microcarpa), rose gum (Eucalyptus grandis) and Queensland lacebark (Brachychiton discolor). The relative ordering of maximum photosynthesis and conductance across species was not entirely predictable based on our current knowledge of the native habitats of each species: several other species had similar native climates to Jacaranda and honey locust, yet

  15. Comparing i-Tree modeled ozone deposition with field measurements in a periurban Mediterranean forest

    Science.gov (United States)

    A. Morani; D. Nowak; S. Hirabayashi; G. Guidolotti; M. Medori; V. Muzzini; S. Fares; G. Scarascia Mugnozza; C. Calfapietra

    2014-01-01

    Ozone flux estimates from the i-Tree model were compared with ozone flux measurements using the Eddy Covariance technique in a periurban Mediterranean forest near Rome (Castelporziano). For the first time i-Tree model outputs were compared with field measurements in relation to dry deposition estimates. Results showed generally a...

  16. Search for Higgs boson in beyond standard model scenarios

    Indian Academy of Sciences (India)

    The principal physics motivation of the LHC experiments is to search for the Higgs boson and to probe the physics of TeV energy scale. Potential of discovery for Higgs bosons in various scenarios beyond standard model have been estimated for both CMS and ATLAS experiments through detailed detector simulations.

  17. [Responses of Pinus tabulaeformis forest ecosystem in North China to climate change and elevated CO2: a simulation based on BIOME-BGC model and tree-ring data].

    Science.gov (United States)

    He, Jun-Jie; Peng, Xing-Yuan; Chen, Zhen-Ju; Cui, Ming-Xing; Zhang, Xian-Liang; Zhou, Chang-Hong

    2012-07-01

    Based on BIOME-BGC model and tree-ring data, a modeling study was conducted to estimate the dynamic changes of the net primary productivity (NPP) of Pinus tabulaeformis forest ecosystem in North China in 1952-2008, and explore the responses of the radial growth and NPP to regional climate warming as well as the dynamics of the NPP in the future climate change scenarios. The simulation results indicated the annual NPP of the P. tabulaeformis ecosystem in 1952-2008 fluctuated from 244.12 to 645.31 g C x m(-2) x a(-1), with a mean value of 418.6 g C x m(-2) x a(-1) The mean air temperature in May-June and the precipitation from previous August to current July were the main factors limiting the radial growth of P. tabulaeformis and the NPP of P. tabulaeformis ecosystem. In the study period, both the radial growth and the NPP presented a decreasing trend due to the regional warming and drying climate condition. In the future climate scenarios, the NPP would have positive responses to the increase of air temperature, precipitation, and their combination. The elevated CO2 would benefit the increase of the NPP, and the increment would be about 16.1% due to the CO2 fertilization. At both ecosystem and regional scales, the tree-ring data would be an ideal proxy to predict the ecosystem dynamic change, and could be used to validate and calibrate the process-based ecosystem models including BIOME-BGC.

  18. Identification of reference accident scenarios in SEVESO establishments

    International Nuclear Information System (INIS)

    Delvosalle, C.; Fievez, C.; Pipart, A.; Fabrega, J. Casal; Planas, E.; Christou, M.; Mushtaq, F.

    2005-01-01

    In the frame of the ESREL special session on ARAMIS project, this paper aims at presenting the work carried out in the first Work Package, devoted to the definition of accident scenarios. This topic is a key-point in risk assessment, and serves as basis for the whole risk quantification. A first part of the work aims at building a Methodology for the Identification of Major Accident Hazards (MIMAH), which is carried out with the development of generic fault and event trees based on a typology of equipment and substances. This work is coupled with an historical analysis of accidents. In a second part, influence of safety devices and policies will be considered, in order to build a Methodology for the Identification of Reference Accident Scenarios (MIRAS). This last one will take into account safety systems and lead to obtain more realistic scenarios

  19. Long-term scenario alternatives and their implications: LEAP model application of Panama's electricity sector

    International Nuclear Information System (INIS)

    McPherson, Madeleine; Karney, Bryan

    2014-01-01

    Panama recently enacted a new law, which aims to promote wind energy by mandating long term power purchase tenders. The implications of this new law lend some uncertainty to Panama's electricity development pathway. This paper quantitatively analyzes the current status of power generation in Panama, and explores various potential future scenarios and the associated impacts on the system marginal cost, global warming potential, and resource diversity index. To this end, this study applies the scenario development methodology developed by Schwartz in the context of the energy-economic modeling platform ‘Long-range Energy Alternative Planning’ (LEAP). Four scenarios are developed and analyzed. The Business as Usual scenario extrapolates the electricity generation trend that has been observed over the last decade; it is compared to three alternative scenarios which have more specific objectives. Scenario 1 encourages climate mitigation without incorporating new technologies in the generation mix, Scenario 2 maximizes resource diversity, and Scenario 3 minimizes global warming potential. For each scenario, the composition of the electricity generation profile, system marginal cost, global warming potential, and resource diversity is predicted quantitatively. These scenarios to not attempt to forecast likely developments, but rather illuminate the tradeoffs that different development pathways entail. - Highlights: • This paper models Panama's electricity sector using the LEAP model platform. • Four scenarios are developed and analyzed. • Impact analysis includes: system cost, global warming potential, resource diversity index. • Panama can achieve a sustainable grid with existing technologies and costs. • There is an tradeoff between the resource diversity and global warming potential

  20. Modelling effects of tree population dynamics, tree throw and pit-mound formation/diffusion on microtopography over time in different forest settings

    Science.gov (United States)

    Martin, Y. E.; Johnson, E. A.; Gallaway, J.; Chaikina, O.

    2011-12-01

    Herein we conduct a followup investigation to an earlier research project in which we developed a numerical model of tree population dynamics, tree throw, and sediment transport associated with the formation of pit-mound features for Hawk Creek watershed, Canadian Rockies (Gallaway et al., 2009). We extend this earlier work by exploring the most appropriate transport relations to simulate the diffusion over time of newly-formed pit-pound features due to tree throw. We combine our earlier model with a landscape development model that can incorporate these diffusive transport relations. Using these combined models, changes in hillslope microtopography over time associated with the formation of pit-mound features and their decay will be investigated. The following ideas have motivated this particular study: (i) Rates of pit-mound degradation remain a source of almost complete speculation, as there is almost no long-term information on process rates. Therefore, we will attempt to tackle the issue of pit-mound degradation in a methodical way that can guide future field studies; (ii) The degree of visible pit-mound topography at any point in time on the landscape is a joint function of the rate of formation of new pit-mound features due to tree death/topple and their magnitude vs. the rate of decay of pit-mound features. An example of one interesting observation that arises is the following: it appears that pit-mound topography is often more pronounced in some eastern North American forests vs. field sites along the eastern slopes of the Canadian Rockies. Why is this the case? Our investigation begins by considering whether pit-mound decay might occur by linear or nonlinear diffusion. What differences might arise depending on which diffusive approach is adopted? What is the magnitude of transport rates associated with these possible forms of transport relations? We explore linear and nonlinear diffusion at varying rates and for different sizes of pit-mound pairs using a

  1. Exploring Bioeconomy Growth through the Public Release of the Biomass Scenario Model

    Energy Technology Data Exchange (ETDEWEB)

    Newes, Emily K [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Biddy, Mary J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Bush, Brian W [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Inman, Daniel J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Vimmerstedt, Laura J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Peterson, Steve [Lexidyne, LLC

    2017-08-02

    The Biomass Scenario Model (BSM) is an important tool for exploring vibrant future bioeconomy scenarios that leverage domestic resources. Developed by NREL and BETO, this model of the domestic biofuels supply chain has been used to explore success strategies for BETO's activities towards bioeconomy growth. The BSM offers a robust test bed for detailed exploration of effects of BETO activities within the complex context of resource availability; physical, technological, and economic constraints; behavior; and policy. The public release of the model in 2017 will allow broad engagement with the theme of the conference as model users can analyze bioeconomy growth, domestic biomass resource use, and associated effects. The BSM is a carefully validated, state-of-the-art, dynamic model of the biomass to biofuels supply chain. Using a system dynamics simulation modeling approach, the model tracks long-term deployment of biofuels given technology development and investment, considering land availability, the competing oil market, consumer demand, and government policies over time. Sample outputs include biofuels production, feedstock use, capital investment, incentives, and costs of feedstocks and fuels. BSM scenarios reveal technological, economic, and policy challenges, as well as opportunities for dynamic growth of the bioeconomy with strategic public and private investment at key points in the system. The model logic and results have been reviewed extensively, through collaborative analysis, expert reviews and external publications (https://www.zotero.org/groups/bsm_publications/).

  2. M5 model tree based predictive modeling of road accidents on non-urban sections of highways in India.

    Science.gov (United States)

    Singh, Gyanendra; Sachdeva, S N; Pal, Mahesh

    2016-11-01

    This work examines the application of M5 model tree and conventionally used fixed/random effect negative binomial (FENB/RENB) regression models for accident prediction on non-urban sections of highway in Haryana (India). Road accident data for a period of 2-6 years on different sections of 8 National and State Highways in Haryana was collected from police records. Data related to road geometry, traffic and road environment related variables was collected through field studies. Total two hundred and twenty two data points were gathered by dividing highways into sections with certain uniform geometric characteristics. For prediction of accident frequencies using fifteen input parameters, two modeling approaches: FENB/RENB regression and M5 model tree were used. Results suggest that both models perform comparably well in terms of correlation coefficient and root mean square error values. M5 model tree provides simple linear equations that are easy to interpret and provide better insight, indicating that this approach can effectively be used as an alternative to RENB approach if the sole purpose is to predict motor vehicle crashes. Sensitivity analysis using M5 model tree also suggests that its results reflect the physical conditions. Both models clearly indicate that to improve safety on Indian highways minor accesses to the highways need to be properly designed and controlled, the service roads to be made functional and dispersion of speeds is to be brought down. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Modeling the effectiveness of tree planting to mitigate habitat loss in blue oak woodlands

    Science.gov (United States)

    Richard B. Standiford; Douglas McCreary; William Frost

    2002-01-01

    Many local conservation policies have attempted to mitigate the loss of oak woodland habitat resulting from conversion to urban or intensive agricultural land uses through tree planting. This paper models the development of blue oak (Quercus douglasii) stand structure attributes over 50 years after planting. The model uses a single tree, distance...

  4. Regional deposition of thoron progeny in models of the human tracheobronchial tree

    Energy Technology Data Exchange (ETDEWEB)

    Smith, S.M.; Cheng, Yung-Sung; Yeh, Hsu-Chi

    1995-12-01

    Models of the human tracheobronchial tree have been used to determine total and regional aerosol deposition of inhaled particles. Particle sizes measured in these studies have all been > 40 nm in diameter. The deposition of aerosols < 40 nm in diameter has not been measured. Particles in the ultrafine aerosol size range include some combustion aerosols and indoor radon progeny. Also, the influence of reduced lung size and airflow rates on particle deposition in young children has not been determined. With their smaller lung size and smaller minute volumes, children may be at increased risk from ultrafine pollutants. In order to accurately determine dose of inhaled aerosols, the effects of particle size, minute volume, and age at exposure must be quantified. The purpose of this study was to determine the deposition efficiency of ultrafine aerosols smaller than 40 nm in diameter in models of the human tracheobronchia tree. This study demonstrates that the deposition efficiency of aerosols in the model of the child`s tracheobronchial tree may be slightly higher than in the adult models.

  5. Regional deposition of thoron progeny in models of the human tracheobronchial tree

    International Nuclear Information System (INIS)

    Smith, S.M.; Cheng, Yung-Sung; Yeh, Hsu-Chi.

    1995-01-01

    Models of the human tracheobronchial tree have been used to determine total and regional aerosol deposition of inhaled particles. Particle sizes measured in these studies have all been > 40 nm in diameter. The deposition of aerosols < 40 nm in diameter has not been measured. Particles in the ultrafine aerosol size range include some combustion aerosols and indoor radon progeny. Also, the influence of reduced lung size and airflow rates on particle deposition in young children has not been determined. With their smaller lung size and smaller minute volumes, children may be at increased risk from ultrafine pollutants. In order to accurately determine dose of inhaled aerosols, the effects of particle size, minute volume, and age at exposure must be quantified. The purpose of this study was to determine the deposition efficiency of ultrafine aerosols smaller than 40 nm in diameter in models of the human tracheobronchia tree. This study demonstrates that the deposition efficiency of aerosols in the model of the child's tracheobronchial tree may be slightly higher than in the adult models

  6. Study of traffic-related pollutant removal from street canyon with trees: dispersion and deposition perspective.

    Science.gov (United States)

    Morakinyo, Tobi Eniolu; Lam, Yun Fat

    2016-11-01

    Numerical experiments involving street canyons of varying aspect ratio with traffic-induced pollutants (PM 2.5 ) and implanted trees of varying aspect ratio, leaf area index, leaf area density distribution, trunk height, tree-covered area, and tree planting pattern under different wind conditions were conducted using a computational fluid dynamics (CFD) model, ENVI-met. Various aspects of dispersion and deposition were investigated, which include the influence of various tree configurations and wind condition on dispersion within the street canyon, pollutant mass at the free stream layer and street canyon, and comparison between mass removal by surface (leaf) deposition and mass enhancement due to the presence of trees. Results revealed that concentration level was enhanced especially within pedestrian level in street canyons with trees relative to their tree-free counterparts. Additionally, we found a dependence of the magnitude of concentration increase (within pedestrian level) and decrease (above pedestrian level) due to tree configuration and wind condition. Furthermore, we realized that only ∼0.1-3 % of PM 2.5 was dispersed to the free stream layer while a larger percentage (∼97 %) remained in the canyon, regardless of its aspect ratio, prevailing wind condition, and either tree-free or with tree (of various configuration). Lastly, results indicate that pollutant removal due to deposition on leaf surfaces is potentially sufficient to counterbalance the enhancement of PM 2.5 by such trees under some tree planting scenarios and wind conditions.

  7. A CVAR scenario for a standard monetary model using theory-consistent expectations

    DEFF Research Database (Denmark)

    Juselius, Katarina

    2017-01-01

    A theory-consistent CVAR scenario describes a set of testable regularities capturing basic assumptions of the theoretical model. Using this concept, the paper considers a standard model for exchange rate determination and shows that all assumptions about the model's shock structure and steady...

  8. A Survey of Game Theoretic Approaches to Modelling Decision-Making in Information Warfare Scenarios

    Directory of Open Access Journals (Sweden)

    Kathryn Merrick

    2016-07-01

    Full Text Available Our increasing dependence on information technologies and autonomous systems has escalated international concern for information- and cyber-security in the face of politically, socially and religiously motivated cyber-attacks. Information warfare tactics that interfere with the flow of information can challenge the survival of individuals and groups. It is increasingly important that both humans and machines can make decisions that ensure the trustworthiness of information, communication and autonomous systems. Subsequently, an important research direction is concerned with modelling decision-making processes. One approach to this involves modelling decision-making scenarios as games using game theory. This paper presents a survey of information warfare literature, with the purpose of identifying games that model different types of information warfare operations. Our contribution is a systematic identification and classification of information warfare games, as a basis for modelling decision-making by humans and machines in such scenarios. We also present a taxonomy of games that map to information warfare and cyber crime problems as a precursor to future research on decision-making in such scenarios. We identify and discuss open research questions including the role of behavioural game theory in modelling human decision making and the role of machine decision-making in information warfare scenarios.

  9. Expansion of Protected Areas under Climate Change: An Example of Mountainous Tree Species in Taiwan

    Directory of Open Access Journals (Sweden)

    Wei-Chih Lin

    2014-11-01

    Full Text Available Tree species in mountainous areas are expected to shift their distribution upward in elevation in response to climate change, calling for a potential redesign of existing protected areas. This study aims to predict whether or not the distributions of two high-mountain tree species, Abies (Abies kawakamii and Tsuga (Tsuga chinensis var. formosana, will significantly shift upward due to temperature change, and whether current protected areas will be suitable for conserving these species. Future temperature change was projected for 15 different future scenarios produced from five global climate models. Shifts in Abies and Tsuga distributions were then predicted through the use of species distribution models (SDMs which included occurrence data of Abies and Tsuga, as well as seasonal temperature, and elevation. The 25 km × 25 km downscaled General Circulation Model (GCMs data for 2020–2039 produced by the Taiwan Climate Change Projection and Information Platform was adopted in this study. Habitat suitability in the study area was calculated using maximum entropy model under different climatic scenarios. A bootstrap method was applied to assess the parameter uncertainty of the maximum entropy model. In comparison to the baseline projection, we found that there are significant differences in suitable habitat distributions for Abies and Tsuga under seven of the 15 scenarios. The results suggest that mountainous ecosystems will be substantially impacted by climate change. We also found that the uncertainty originating from GCMs and the parameters of the SDM contribute most to the overall level of variability in species distributions. Finally, based on the uncertainty analysis and the shift in habitat suitability, we applied systematic conservation planning approaches to identify suitable areas to add to Taiwan’s protected area network.

  10. Linking state-and-transition simulation and timber supply models for forest biomass production scenarios

    Science.gov (United States)

    Costanza, Jennifer; Abt, Robert C.; McKerrow, Alexa; Collazo, Jaime

    2015-01-01

    We linked state-and-transition simulation models (STSMs) with an economics-based timber supply model to examine landscape dynamics in North Carolina through 2050 for three scenarios of forest biomass production. Forest biomass could be an important source of renewable energy in the future, but there is currently much uncertainty about how biomass production would impact landscapes. In the southeastern US, if forests become important sources of biomass for bioenergy, we expect increased land-use change and forest management. STSMs are ideal for simulating these landscape changes, but the amounts of change will depend on drivers such as timber prices and demand for forest land, which are best captured with forest economic models. We first developed state-and-transition model pathways in the ST-Sim software platform for 49 vegetation and land-use types that incorporated each expected type of landscape change. Next, for the three biomass production scenarios, the SubRegional Timber Supply Model (SRTS) was used to determine the annual areas of thinning and harvest in five broad forest types, as well as annual areas converted among those forest types, agricultural, and urban lands. The SRTS output was used to define area targets for STSMs in ST-Sim under two scenarios of biomass production and one baseline, business-as-usual scenario. We show that ST-Sim output matched SRTS targets in most cases. Landscape dynamics results indicate that, compared with the baseline scenario, forest biomass production leads to more forest and, specifically, more intensively managed forest on the landscape by 2050. Thus, the STSMs, informed by forest economics models, provide important information about potential landscape effects of bioenergy production.

  11. Linking state-and-transition simulation and timber supply models for forest biomass production scenarios

    Directory of Open Access Journals (Sweden)

    Jennifer K. Costanza

    2015-03-01

    Full Text Available We linked state-and-transition simulation models (STSMs with an economics-based timber supply model to examine landscape dynamics in North Carolina through 2050 for three scenarios of forest biomass production. Forest biomass could be an important source of renewable energy in the future, but there is currently much uncertainty about how biomass production would impact landscapes. In the southeastern US, if forests become important sources of biomass for bioenergy, we expect increased land-use change and forest management. STSMs are ideal for simulating these landscape changes, but the amounts of change will depend on drivers such as timber prices and demand for forest land, which are best captured with forest economic models. We first developed state-and-transition model pathways in the ST-Sim software platform for 49 vegetation and land-use types that incorporated each expected type of landscape change. Next, for the three biomass production scenarios, the SubRegional Timber Supply Model (SRTS was used to determine the annual areas of thinning and harvest in five broad forest types, as well as annual areas converted among those forest types, agricultural, and urban lands. The SRTS output was used to define area targets for STSMs in ST-Sim under two scenarios of biomass production and one baseline, business-as-usual scenario. We show that ST-Sim output matched SRTS targets in most cases. Landscape dynamics results indicate that, compared with the baseline scenario, forest biomass production leads to more forest and, specifically, more intensively managed forest on the landscape by 2050. Thus, the STSMs, informed by forest economics models, provide important information about potential landscape effects of bioenergy production.

  12. Running scenarios using the Waste Tank Safety and Operations Hanford Site model

    International Nuclear Information System (INIS)

    Stahlman, E.J.

    1995-11-01

    Management of the Waste Tank Safety and Operations (WTS ampersand O) at Hanford is a large and complex task encompassing 177 tanks and having a budget of over $500 million per year. To assist managers in this task, a model based on system dynamics was developed by the Massachusetts Institute of Technology. The model simulates the WTS ampersand O at the Hanford Tank Farms by modeling the planning, control, and flow of work conducted by Managers, Engineers, and Crafts. The model is described in Policy Analysis of Hanford Tank Farm Operations with System Dynamics Approach (Kwak 1995b) and Management Simulator for Hanford Tank Farm Operations (Kwak 1995a). This document provides guidance for users of the model in developing, running, and analyzing results of management scenarios. The reader is assumed to have an understanding of the model and its operation. Important parameters and variables in the model are described, and two scenarios are formulated as examples

  13. EDITORIAL: Where next with global environmental scenarios? Where next with global environmental scenarios?

    Science.gov (United States)

    O'Neill, Brian; Pulver, Simone; Van Deveer, Stacy; Garb, Yaakov

    2008-12-01

    Scenarios have become a standard tool in the portfolio of techniques that scientists and policy-makers use to envision and plan for the future. Defined as plausible, challenging and relevant stories about how the future might unfold that integrate quantitative models with qualitative assessments of social and political trends, scenarios are a central component in assessment processes for a range of global issues, including climate change, biodiversity, agriculture, and energy. Yet, despite their prevalence, systematic analysis of scenarios is in its beginning stages. Fundamental questions remain about both the epistemology and scientific credibility of scenarios and their roles in policymaking and social change. Answers to these questions have the potential to determine the future of scenario analyses. Is scenario analysis moving in the direction of earth system governance informed by global scenarios generated through increasingly complex and comprehensive models integrating socio-economic and earth systems? Or will global environmental scenario analyses lose favour compared to more focused, policy-driven, regionally specific modelling? These questions come at an important time for the climate change issue, given that the scenario community, catalyzed by the Intergovernmental Panel on Climate Change (IPCC), is currently preparing to embark on a new round of scenario development processes aimed at coordinating research and assessment, and informing policy, over the next five to ten years. These and related questions about where next to go with global environmental scenarios animated a workshop held at Brown University (Note1) that brought together leading practitioners and scholars of global environmental change scenarios from research, policy-making, advocacy, and business settings. The workshop aimed to provide an overview of current practices/best practices in scenario production and scenario use across a range of global environmental change arenas. Participants

  14. Study on competitive interaction models in Cayley tree

    International Nuclear Information System (INIS)

    Moreira, J.G.M.A.

    1987-12-01

    We propose two kinds of models in the Cayley tree to simulate Ising models with axial anisotropy in the cubic lattice. The interaction in the direction of the anisotropy is simulated by the interaction along the branches of the tree. The interaction in the planes perpendicular to the anisotropy direction, in the first model, is simulated by interactions between spins in neighbour branches of the same generation arising from same site of the previous generation. In the second model, the simulation of the interaction in the planes are produced by mean field interactions among all spins in sites of the same generation arising from the same site of the previous generations. We study these models in the limit of infinite coordination number. First, we analyse a situation with antiferromagnetic interactions along the branches between first neighbours only, and we find the analogous of a metamagnetic Ising model. In the following, we introduce competitive interactions between first and second neighbours along the branches, to simulate the ANNNI model. We obtain one equation of differences which relates the magnetization of one generation with the magnetization of the two previous generations, to permit a detailed study of the modulated phase region. We note that the wave number of the modulation, for one fixed temperature, changes with the competition parameter to form a devil's staircase with a fractal dimension which increases with the temperature. We discuss the existence of strange atractors, related to a possible caothic phase. Finally, we show the obtained results when we consider interactions along the branches with three neighbours. (author)

  15. Effects of uncertainty in model predictions of individual tree volume on large area volume estimates

    Science.gov (United States)

    Ronald E. McRoberts; James A. Westfall

    2014-01-01

    Forest inventory estimates of tree volume for large areas are typically calculated by adding model predictions of volumes for individual trees. However, the uncertainty in the model predictions is generally ignored with the result that the precision of the large area volume estimates is overestimated. The primary study objective was to estimate the effects of model...

  16. Cluster Risk of Walking Scenarios Based on Macroscopic Flow Model and Crowding Force Analysis

    Directory of Open Access Journals (Sweden)

    Xiaohong Li

    2018-02-01

    Full Text Available In recent years, accidents always happen in confined space such as metro stations because of congestion. Various researchers investigated the patterns of dense crowd behaviors in different scenarios via simulations or experiments and proposed methods for avoiding accidents. In this study, a classic continuum macroscopic model was applied to simulate the crowded pedestrian flow in typical scenarios such as at bottlenecks or with an obstacle. The Lax–Wendroff finite difference scheme and artificial viscosity filtering method were used to discretize the model to identify high-density risk areas. Furthermore, we introduced a contact crowding force test of the interactions among pedestrians at bottlenecks. Results revealed that in the most dangerous area, the individual on the corner position bears the maximum pressure in such scenarios is 90.2 N, and there is an approximate exponential relationship between crowding force and density indicated by our data. The results and findings presented in this paper can facilitate more reasonable and precise simulation models by utilizing crowding force and crowd density and ensure the safety of pedestrians in high-density scenarios.

  17. Visioning the Future: Scenarios Modeling of the Florida Coastal Everglades

    Science.gov (United States)

    Flower, Hilary; Rains, Mark; Fitz, Carl

    2017-11-01

    In this paper, we provide screening-level analysis of plausible Everglades ecosystem response by 2060 to sea level rise (0.50 m) interacting with macroclimate change (1.5 °C warming, 7% increase in evapotranspiration, and rainfall that either increases or decreases by 10%). We used these climate scenarios as input to the Ecological Landscape Model to simulate changes to seven interactive hydro-ecological metrics. Mangrove forest and other marine influences migrated up to 15 km inland in both scenarios, delineated by the saltwater front. Freshwater habitat area decreased by 25-30% under our two climate change scenarios and was largely replaced by mangroves and, in the increased rainfall scenario, open water as well. Significant mangroves drowned along northern Florida Bay in both climate change scenarios due to sea level rise. Increased rainfall of 10% provided significant benefits to the spatial and temporal salinity regime within the marine-influenced zone, providing a more gradual and natural adjustment for at-risk flora and fauna. However, increased rainfall also increased the risk of open water, due to water depths that inhibited mangrove establishment and reduced peat accumulation rates. We infer that ecological effects related to sea level rise may occur in the extreme front-edge of saltwater intrusion, that topography will control the incursion of this zone as sea level rises, and that differences in freshwater availability will have ecologically significant effects on ecosystem resilience through the temporal and spatial pattern of salinity changes.

  18. Normal and Abnormal Scenario Modeling with GoldSim for Radioactive Waste Disposal System

    International Nuclear Information System (INIS)

    Lee, Youn Myoung; Jeong, Jong Tae

    2010-08-01

    A modeling study and development of a total system performance assessment (TSPA) template program, by which an assessment of safety and performance for the radioactive waste repository with normal and/or abnormal nuclide release cases could be assessed has been carried out by utilizing a commercial development tool program, GoldSim. Scenarios associated with the various FEPs and involved in the performance of the proposed repository in view of nuclide transport and transfer both in the geosphere and biosphere has been also carried out. Selected normal and abnormal scenarios that could alter groundwater flow scheme and then nuclide transport are modeled with the template program. To this end in-depth system models for the normal and abnormal well and earthquake scenarios that are conceptually and rather practically described and then ready for implementing into a GoldSim TSPA template program are introduced with conceptual schemes for each repository system. Illustrative evaluations with data currently available are also shown

  19. Phenomenological viability of orbifold models with three Higgs families

    International Nuclear Information System (INIS)

    Escudero, Nicolas; Munoz, Carlos; Teixeira, Ana M.

    2006-01-01

    We discuss the phenomenological viability of string multi-Higgs doublet models, namely a scenario of heterotic Z 3 orbifolds with two Wilson lines, which naturally predicts three supersymmetric families of matter and Higgs fields. We study the orbifold parameter space, and discuss the compatibility of the predicted Yukawa couplings with current experimental data. We address the implications of tree-level flavour changing neutral processes in constraining the Higgs sector of the model, finding that viable scenarios can be obtained for a reasonably light Higgs spectrum. We also take into account the tree-level contributions to indirect CP violation, showing that the experimental value of ε K can be accommodated in the present framework

  20. Biogeochemical modelling vs. tree-ring data - comparison of forest ecosystem productivity estimates

    Science.gov (United States)

    Zorana Ostrogović Sever, Maša; Barcza, Zoltán; Hidy, Dóra; Paladinić, Elvis; Kern, Anikó; Marjanović, Hrvoje

    2017-04-01

    Forest ecosystems are sensitive to environmental changes as well as human-induce disturbances, therefore process-based models with integrated management modules represent valuable tool for estimating and forecasting forest ecosystem productivity under changing conditions. Biogeochemical model Biome-BGC simulates carbon, nitrogen and water fluxes, and it is widely used for different terrestrial ecosystems. It was modified and parameterised by many researchers in the past to meet the specific local conditions. In this research, we used recently published improved version of the model Biome-BGCMuSo (BBGCMuSo), with multilayer soil module and integrated management module. The aim of our research is to validate modelling results of forest ecosystem productivity (NPP) from BBGCMuSo model with observed productivity estimated from an extensive dataset of tree-rings. The research was conducted in two distinct forest complexes of managed Pedunculate oak in SE Europe (Croatia), namely Pokupsko basin and Spačva basin. First, we parameterized BBGCMuSo model at a local level using eddy-covariance (EC) data from Jastrebarsko EC site. Parameterized model was used for the assessment of productivity on a larger scale. Results of NPP assessment with BBGCMuSo are compared with NPP estimated from tree ring data taken from trees on over 100 plots in both forest complexes. Keywords: Biome-BGCMuSo, forest productivity, model parameterization, NPP, Pedunculate oak

  1. Implications of Model Structure and Detail for Utility Planning: Scenario Case Studies Using the Resource Planning Model

    Energy Technology Data Exchange (ETDEWEB)

    Mai, Trieu [National Renewable Energy Lab. (NREL), Golden, CO (United States); Barrows, Clayton [National Renewable Energy Lab. (NREL), Golden, CO (United States); Lopez, Anthony [National Renewable Energy Lab. (NREL), Golden, CO (United States); Hale, Elaine [National Renewable Energy Lab. (NREL), Golden, CO (United States); Dyson, Mark [National Renewable Energy Lab. (NREL), Golden, CO (United States); Eurek, Kelly [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-04-01

    In this report, we analyze the impacts of model configuration and detail in capacity expansion models, computational tools used by utility planners looking to find the least cost option for planning the system and by researchers or policy makers attempting to understand the effects of various policy implementations. The present analysis focuses on the importance of model configurations — particularly those related to capacity credit, dispatch modeling, and transmission modeling — to the construction of scenario futures. Our analysis is primarily directed toward advanced tools used for utility planning and is focused on those impacts that are most relevant to decisions with respect to future renewable capacity deployment. To serve this purpose, we develop and employ the NREL Resource Planning Model to conduct a case study analysis that explores 12 separate capacity expansion scenarios of the Western Interconnection through 2030.

  2. Effect of different tree mortality patterns on stand development in the forest model SIBYLA

    Directory of Open Access Journals (Sweden)

    Trombik Jiří

    2016-09-01

    Full Text Available Forest mortality critically affects stand structure and the quality of ecosystem services provided by forests. Spruce bark beetle (Ips typographus generates rather complex infestation and mortality patterns, and implementation of such patterns in forest models is challenging. We present here the procedure, which allows to simulate the bark beetle-related tree mortality in the forest dynamics model Sibyla. We explored how sensitive various production and stand structure indicators are to tree mortality patterns, which can be generated by bark beetles. We compared the simulation outputs for three unmanaged forest stands with 40, 70 and 100% proportion of spruce as affected by the disturbance-related mortality that occurred in a random pattern and in a patchy pattern. The used tree species and age class-specific mortality rates were derived from the disturbance-related mortality records from Slovakia. The proposed algorithm was developed in the SQLite using the Python language, and the algorithm allowed us to define the degree of spatial clustering of dead trees ranging from a random distribution to a completely clustered distribution; a number of trees that died in either mode is set to remain equal. We found significant differences between the long-term developments of the three investigated forest stands, but we found very little effect of the tested mortality modes on stand increment, tree species composition and diversity, and tree size diversity. Hence, our hypothesis that the different pattern of dead trees emergence should affect the competitive interactions between trees and regeneration, and thus affect selected productivity and stand structure indicators was not confirmed.

  3. (Almost) practical tree codes

    KAUST Repository

    Khina, Anatoly

    2016-08-15

    We consider the problem of stabilizing an unstable plant driven by bounded noise over a digital noisy communication link, a scenario at the heart of networked control. To stabilize such a plant, one needs real-time encoding and decoding with an error probability profile that decays exponentially with the decoding delay. The works of Schulman and Sahai over the past two decades have developed the notions of tree codes and anytime capacity, and provided the theoretical framework for studying such problems. Nonetheless, there has been little practical progress in this area due to the absence of explicit constructions of tree codes with efficient encoding and decoding algorithms. Recently, linear time-invariant tree codes were proposed to achieve the desired result under maximum-likelihood decoding. In this work, we take one more step towards practicality, by showing that these codes can be efficiently decoded using sequential decoding algorithms, up to some loss in performance (and with some practical complexity caveats). We supplement our theoretical results with numerical simulations that demonstrate the effectiveness of the decoder in a control system setting.

  4. Rate of tree carbon accumulation increases continuously with tree size.

    Science.gov (United States)

    Stephenson, N L; Das, A J; Condit, R; Russo, S E; Baker, P J; Beckman, N G; Coomes, D A; Lines, E R; Morris, W K; Rüger, N; Alvarez, E; Blundo, C; Bunyavejchewin, S; Chuyong, G; Davies, S J; Duque, A; Ewango, C N; Flores, O; Franklin, J F; Grau, H R; Hao, Z; Harmon, M E; Hubbell, S P; Kenfack, D; Lin, Y; Makana, J-R; Malizia, A; Malizia, L R; Pabst, R J; Pongpattananurak, N; Su, S-H; Sun, I-F; Tan, S; Thomas, D; van Mantgem, P J; Wang, X; Wiser, S K; Zavala, M A

    2014-03-06

    Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest carbon cycle--particularly net primary productivity and carbon storage--increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute tree mass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age. Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree's total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth, inform efforts to undertand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence.

  5. Projection of U.S. forest sector carbon sequestration under U.S. and global timber market and wood energy consumption scenarios, 2010-2060

    Science.gov (United States)

    Prakash Nepal; Peter J. Ince; Kenneth E. Skog; Sun J. Chang

    2012-01-01

    This study provides a modeling framework to examine change over time in U.S. forest sector carbon inventory (in U.S. timberland tree biomass and harvested wood products) for alternative projections of U.S. and global timber markets, including wood energy consumption, based on established IPCC/RPA scenarios. Results indicated that the U.S. forest sector’s projected...

  6. On P-adic λ-model on the Cayley tree

    International Nuclear Information System (INIS)

    Khamaraev, M.; Mukhamedov, F.

    2004-04-01

    We consider a nearest-neighbour p-adic A-model with spin values ±1 on the Cayley tree of order k ≥ 1. We prove that a p-adic Gibbs measure is unique for p≥ 3. If p 2 then we find a condition which guarantees uniqueness of p-adic Gibbs measure. Besides, the results are applied to the p-adic Ising model. (author)

  7. A Root water uptake model to compensate disease stress in citrus trees

    Science.gov (United States)

    Peddinti, S. R.; Kambhammettu, B. P.; Lad, R. S.; Suradhaniwar, S.

    2017-12-01

    Plant root water uptake (RWU) controls a number of hydrologic fluxes in simulating unsaturated flow and transport processes. Variable saturated models that simulate soil-water-plant interactions within the rizhosphere do not account for the health of the tree. This makes them difficult to analyse RWU patterns for diseased trees. Improper irrigation management activities on diseased (Phytopthora spp. affected) citrus trees of central India has resulted in a significant reduction in crop yield accompanied by disease escalation. This research aims at developing a quantitative RWU model that accounts for the reduction in water stress as a function of plant disease level (hereafter called as disease stress). A total of four research plots with varying disease severity were considered for our field experimentation. A three-dimensional electrical resistivity tomography (ERT) was performed to understand spatio-temporal distribution in soil moisture following irrigation. Evaporation and transpiration were monitored daily using micro lysimeter and sap flow meters respectively. Disease intensity was quantified (on 0 to 9 scale) using pathological analysis on soil samples. Pedo-physocal and pedo-electric relations were established under controlled laboratory conditions. A non-linear disease stress response function for citrus trees was derived considering phonological, hydrological, and pathological parameters. Results of numerical simulations conclude that the propagation of error in RWU estimates by ignoring the health condition of the tree is significant. The developed disease stress function was then validated in the presence of deficit water and nutrient stress conditions. Results of numerical analysis showed a good agreement with experimental data, corroborating the need for alternate management practices for disease citrus trees.

  8. Coupled 0D-1D CFD Modeling of Right Heart and Pulmonary Artery Morphometry Tree

    Science.gov (United States)

    Dong, Melody; Yang, Weiguang; Feinstein, Jeffrey A.; Marsden, Alison

    2017-11-01

    Pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary artery (PA) pressure and remodeling of the distal PAs resulting in right ventricular (RV) dysfunction and failure. It is hypothesized that patients with untreated ventricular septal defects (VSD) may develop PAH due to elevated flows and pressures in the PAs. Wall shear stress (WSS), due to elevated flows, and circumferential stress, due to elevated pressures, are known to play a role in vascular mechanobiology. Thus, simulating VSD hemodynamics and wall mechanics may facilitate our understanding of mechanical stimuli leading to PAH initiation and progression. Although 3D CFD models can capture detailed hemodynamics in the proximal PAs, they cannot easily model hemodynamics and wave propagation in the distal PAs, where remodeling occurs. To improve current PA models, we will present a new method that couples distal PA hemodynamics with RV function. Our model couples a 0D lumped parameter model of the RV to a 1D model of the PA tree, based on human PA morphometry data, to characterize RV performance and WSS changes in the PA tree. We will compare a VSD 0D-1D model and a 0D-3D model coupled to a mathematical morphometry tree model to quantify WSS in the entire PA vascular tree.

  9. Land-Use Scenarios: National-Scale Housing-Density Scenarios Consistent with Climate Change Storylines (Final Report)

    Science.gov (United States)

    EPA announced the availability of the final report, Land-Use Scenarios: National-Scale Housing-Density Scenarios Consistent with Climate Change Storylines. This report describes the scenarios and models used to generate national-scale housing density scenarios for the con...

  10. Effects of lightning on trees: A predictive model based on in situ electrical resistivity.

    Science.gov (United States)

    Gora, Evan M; Bitzer, Phillip M; Burchfield, Jeffrey C; Schnitzer, Stefan A; Yanoviak, Stephen P

    2017-10-01

    The effects of lightning on trees range from catastrophic death to the absence of observable damage. Such differences may be predictable among tree species, and more generally among plant life history strategies and growth forms. We used field-collected electrical resistivity data in temperate and tropical forests to model how the distribution of power from a lightning discharge varies with tree size and identity, and with the presence of lianas. Estimated heating density (heat generated per volume of tree tissue) and maximum power (maximum rate of heating) from a standardized lightning discharge differed 300% among tree species. Tree size and morphology also were important; the heating density of a hypothetical 10 m tall Alseis blackiana was 49 times greater than for a 30 m tall conspecific, and 127 times greater than for a 30 m tall Dipteryx panamensis . Lianas may protect trees from lightning by conducting electric current; estimated heating and maximum power were reduced by 60% (±7.1%) for trees with one liana and by 87% (±4.0%) for trees with three lianas. This study provides the first quantitative mechanism describing how differences among trees can influence lightning-tree interactions, and how lianas can serve as natural lightning rods for trees.

  11. Regional climate change scenarios

    International Nuclear Information System (INIS)

    Somot, S.

    2005-01-01

    Because studies of the regional impact of climate change need higher spatial resolution than that obtained in standard global climate change scenarios, developing regional scenarios from models is a crucial goal for the climate modelling community. The zoom capacity of ARPEGE-Climat, the Meteo-France climate model, allows use of scenarios with a horizontal resolution of about 50 km over France and the Mediterranean basin. An IPCC-A2 scenario for the end of the 21. century in France shows higher temperatures in each season and more winter and less summer precipitation than now. Tuning the modelled statistical distributions to observed temperature and precipitation allows us to study changes in the frequency of extreme events between today's climate and that at the end of century. The frequency of very hot days in summer will increase. In particular, the frequency of days with a maximum temperature above 35 deg C will be multiplied by a factor of 10, on average. In our scenario, the Toulouse area and Provence might see one quarter of their summer days with a maximum temperature above 35 deg C. (author)

  12. SCENARIO PLANNING AS LEARNING

    Directory of Open Access Journals (Sweden)

    Antonio Lourenço Junior

    2010-10-01

    Full Text Available Scenario Planning has been increasingly used, from its introduction to the decision process as effective tools to test decisions, and improve performance in a dynamic environment (Chermack, 2005. The purpose of this article is to demonstrate the potential of an experimental Scenario Planning Model to mobilize, encourage and add more content to the organization’s decision making process – mainly with respect to Strategic Plans of two governmental institutions, a pharmaceutical company and a technology education foundation.  This study describes the application stages of a hybrid scenario-planning model – herein referred to as Planning as Learning – via action-research, showing the scenarios resulting from the experiment and describes the main results of an assessment of such practice. In order to do that, two well-established Scenario Planning models (Prospective school and Shell’s model were analyzed. They were used as a reference for the proposition and application of an experimental model in the two study objects. A questionnaire was used to assess the technique impact. It was possible to obtain high levels of reliability. In-depth interviews were also conducted with the participants. At the end, the results confirmed the model efficiency as a basis for decision making in the competitive environment in which the two institutions are inserted, also to encourage the learning process as a group, as observed throughout the work.

  13. Modelling Snowmelt Runoff under Climate Change Scenarios in an Ungauged Mountainous Watershed, Northwest China

    Directory of Open Access Journals (Sweden)

    Yonggang Ma

    2013-01-01

    Full Text Available An integrated modeling system has been developed for analyzing the impact of climate change on snowmelt runoff in Kaidu Watershed, Northwest China. The system couples Hadley Centre Coupled Model version 3 (HadCM3 outputs with Snowmelt Runoff Model (SRM. The SRM was verified against observed discharge for outlet hydrological station of the watershed during the period from April to September in 2001 and generally performed well for Nash-Sutcliffe coefficient (EF and water balance coefficient (RE. The EF is approximately over 0.8, and the water balance error is lower than ± 10%, indicating reasonable prediction accuracy. The Statistical Downscaling Model (SDSM was used to downscale coarse outputs of HadCM3, and then the downscaled future climate data were used as inputs of the SRM. Four scenarios were considered for analyzing the climate change impact on snowmelt flow in the Kaidu Watershed. And the results indicated that watershed hydrology would alter under different climate change scenarios. The stream flow in spring is likely to increase with the increased mean temperature; the discharge and peck flow in summer decrease with the decreased precipitation under Scenarios 1 and 2. Moreover, the consideration of the change in cryosphere area would intensify the variability of stream flow under Scenarios 3 and 4. The modeling results provide useful decision support for water resources management.

  14. Spatial Simulation Modelling of Future Forest Cover Change Scenarios in Luangprabang Province, Lao PDR

    Directory of Open Access Journals (Sweden)

    Khamma Homsysavath

    2011-08-01

    Full Text Available Taking Luangprabang province in Lao Peoples’s Democratic Republic (PDR as an example, we simulated future forest cover changes under the business-as-usual (BAU, pessimistic and optimistic scenarios based on the Markov-cellular automata (MCA model. We computed transition probabilities from satellite-derived forest cover maps (1993 and 2000 using the Markov chains, while the “weights of evidence” technique was used to generate transition potential maps. The initial forest cover map (1993, the transition potential maps and the 1993–2000 transition probabilities were used to calibrate the model. Forest cover simulations were then performed from 1993 to 2007 at an annual time-step. The simulated forest cover map for 2007 was compared to the observed (actual forest cover map for 2007 in order to test the accuracy of the model. Following the successful calibration and validation, future forest cover changes were simulated up to 2014 under different scenarios. The MCA simulations under the BAU and pessimistic scenarios projected that current forest areas would decrease, whereas unstocked forest areas would increase in the future. Conversely, the optimistic scenario projected that current forest areas would increase in the future if strict forestry laws enforcing conservation in protected forest areas are implemented. The three simulation scenarios provide a very good case study for simulating future forest cover changes at the subnational level (Luangprabang province. Thus, the future simulated forest cover changes can possibly be used as a guideline to set reference scenarios as well as undertake REDD/REDD+ preparedness activities within the study area.

  15. Application of decision tree model for the ground subsidence hazard mapping near abandoned underground coal mines.

    Science.gov (United States)

    Lee, Saro; Park, Inhye

    2013-09-30

    Subsidence of ground caused by underground mines poses hazards to human life and property. This study analyzed the hazard to ground subsidence using factors that can affect ground subsidence and a decision tree approach in a geographic information system (GIS). The study area was Taebaek, Gangwon-do, Korea, where many abandoned underground coal mines exist. Spatial data, topography, geology, and various ground-engineering data for the subsidence area were collected and compiled in a database for mapping ground-subsidence hazard (GSH). The subsidence area was randomly split 50/50 for training and validation of the models. A data-mining classification technique was applied to the GSH mapping, and decision trees were constructed using the chi-squared automatic interaction detector (CHAID) and the quick, unbiased, and efficient statistical tree (QUEST) algorithms. The frequency ratio model was also applied to the GSH mapping for comparing with probabilistic model. The resulting GSH maps were validated using area-under-the-curve (AUC) analysis with the subsidence area data that had not been used for training the model. The highest accuracy was achieved by the decision tree model using CHAID algorithm (94.01%) comparing with QUEST algorithms (90.37%) and frequency ratio model (86.70%). These accuracies are higher than previously reported results for decision tree. Decision tree methods can therefore be used efficiently for GSH analysis and might be widely used for prediction of various spatial events. Copyright © 2013. Published by Elsevier Ltd.

  16. An Assessment of the Effectiveness of Tree-Based Models for Multi-Variate Flood Damage Assessment in Australia

    Directory of Open Access Journals (Sweden)

    Roozbeh Hasanzadeh Nafari

    2016-07-01

    Full Text Available Flood is a frequent natural hazard that has significant financial consequences for Australia. In Australia, physical losses caused by floods are commonly estimated by stage-damage functions. These methods usually consider only the depth of the water and the type of buildings at risk. However, flood damage is a complicated process, and it is dependent on a variety of factors which are rarely taken into account. This study explores the interaction, importance, and influence of water depth, flow velocity, water contamination, precautionary measures, emergency measures, flood experience, floor area, building value, building quality, and socioeconomic status. The study uses tree-based models (regression trees and bagging decision trees and a dataset collected from 2012 to 2013 flood events in Queensland, which includes information on structural damages, impact parameters, and resistance variables. The tree-based approaches show water depth, floor area, precautionary measures, building value, and building quality to be important damage-influencing parameters. Furthermore, the performance of the tree-based models is validated and contrasted with the outcomes of a multi-parameter loss function (FLFArs from Australia. The tree-based models are shown to be more accurate than the stage-damage function. Consequently, considering more parameters and taking advantage of tree-based models is recommended. The outcome is important for improving established Australian flood loss models and assisting decision-makers and insurance companies dealing with flood risk assessment.

  17. LBA-ECO LC-14 Modeled Deforestation Scenarios, Amazon Basin: 2002-2050

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides the results of the two modeled scenarios for future patterns of deforestation across the Amazon Basin from 2002 to 2050. This larger defined...

  18. LBA-ECO LC-14 Modeled Deforestation Scenarios, Amazon Basin: 2002-2050

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set provides the results of the two modeled scenarios for future patterns of deforestation across the Amazon Basin from 2002 to 2050. This larger...

  19. Scenarios of socio-economic and energy development of the country up to 2010

    International Nuclear Information System (INIS)

    Tsvetanov, P.

    1990-01-01

    The scenarios description is given as the first stage of a procedure of an energy-economy interrelations dynamics study, the other two stages being the formulation and the analysis of the development variants. The scenarios reflect quantitatively the policies and the international conditions for the socio-economic, energy demand and energy supply developments of the country. Two economic development scenarios ('high' - official macroeconomic views and 'low' - economic restructuring and decrease of energy intensity) hierarchically preside over the two corresponding energy demand scenarios of different technological evolutions ('traditional' and 'energy efficiency' oriented one) in the industry, the transport and the domestic and services sectors. Four energy supply system scenarios follow, corresponding to different approaches in the development of the energy conversion technologies and energy carriers, thus constituting a scenario tree of the studies. 16 refs., 2 figs., 7 tab., 1 ann. (R.Ts.)

  20. Multi scenario seismic hazard assessment for Egypt

    Science.gov (United States)

    Mostafa, Shaimaa Ismail; Abd el-aal, Abd el-aziz Khairy; El-Eraki, Mohamed Ahmed

    2018-05-01

    Egypt is located in the northeastern corner of Africa within a sensitive seismotectonic location. Earthquakes are concentrated along the active tectonic boundaries of African, Eurasian, and Arabian plates. The study area is characterized by northward increasing sediment thickness leading to more damage to structures in the north due to multiple reflections of seismic waves. Unfortunately, man-made constructions in Egypt were not designed to resist earthquake ground motions. So, it is important to evaluate the seismic hazard to reduce social and economic losses and preserve lives. The probabilistic seismic hazard assessment is used to evaluate the hazard using alternative seismotectonic models within a logic tree framework. Alternate seismotectonic models, magnitude-frequency relations, and various indigenous attenuation relationships were amended within a logic tree formulation to compute and develop the regional exposure on a set of hazard maps. Hazard contour maps are constructed for peak ground acceleration as well as 0.1-, 0.2-, 0.5-, 1-, and 2-s spectral periods for 100 and 475 years return periods for ground motion on rock. The results illustrate that Egypt is characterized by very low to high seismic activity grading from the west to the eastern part of the country. The uniform hazard spectra are estimated at some important cities distributed allover Egypt. The deaggregation of seismic hazard is estimated at some cities to identify the scenario events that contribute to a selected seismic hazard level. The results of this study can be used in seismic microzonation, risk mitigation, and earthquake engineering purposes.

  1. Regional Models of Diameter as a Function of Individual Tree Attributes, Climate and Site Characteristics for Six Major Tree Species in Alberta, Canada

    Directory of Open Access Journals (Sweden)

    Dan A. MacIsaac

    2011-09-01

    Full Text Available We investigated the relationship of stem diameter to tree, site and stand characteristics for six major tree species (trembling aspen, white birch, balsam fir, lodgepole pine, black spruce, and white spruce in Alberta (Canada with data from Alberta Sustainable Resource Development Permanent Sample Plots. Using non-linear mixed effects modeling techniques, we developed models to estimate diameter at breast height using height, crown and stand attributes. Mixed effects models (with plot as subject using height, crown area, and basal area of the larger trees explained on average 95% of the variation in diameter at breast height across the six species with a root mean square error of 2.0 cm (13.4% of mean diameter. Fixed effects models (without plot as subject including the Natural Sub-Region (NSR information explained on average 90% of the variation in diameter at breast height across the six species with a root mean square error equal to 2.8 cm (17.9% of mean diameter. Selected climate variables provided similar results to models with NSR information. The inclusion of nutrient regime and moisture regime did not significantly improve the predictive ability of these models.

  2. Using Multi-Scenario Tsunami Modelling Results combined with Probabilistic Analyses to provide Hazard Information for the South-WestCoast of Indonesia

    Science.gov (United States)

    Zosseder, K.; Post, J.; Steinmetz, T.; Wegscheider, S.; Strunz, G.

    2009-04-01

    the inundation for a specific area, the wave height at coast at this area and the estimated times of arrival (ETAs) of the waves, caused by one tsunamigenic source with a specific magnitude. These parameters from the several scenarios can overlap each other along the coast and must be combined to get one comprehensive hazard assessment for all possible future tsunamis at the region under observation. The simplest way to derive the inundation probability along the coast using the multiscenario approach is to overlay all scenario inundation results and to determine how often a point on land will be significantly inundated from the various scenarios. But this does not take into account that the used tsunamigenic sources for the modeled scenarios have different likelihoods of causing a tsunami. Hence a statistical analysis of historical data and geophysical investigation results based on numerical modelling results is added to the hazard assessment, which clearly improves the significance of the hazard assessment. For this purpose the present method is developed and contains a complex logical combination of the diverse probabilities assessed like probability of occurrence for different earthquake magnitudes at different localities, probability of occurrence for a specific wave height at the coast and the probability for every point on land likely to get hit by a tsunami. The values are combined by a logical tree technique and quantified by statistical analysis of historical data and of the tsunami modelling results as mentioned before. This results in a tsunami inundation probability map covering the South West Coast of Indonesia which nevertheless shows a significant spatial diversity offering a good base for evacuation planning and mitigation strategies. Keywords: tsunami hazard assessment, tsunami modelling, probabilistic analysis, early warning

  3. Rate of tree carbon accumulation increases continuously with tree size

    Science.gov (United States)

    Stephenson, N.L.; Das, A.J.; Condit, R.; Russo, S.E.; Baker, P.J.; Beckman, N.G.; Coomes, D.A.; Lines, E.R.; Morris, W.K.; Rüger, N.; Álvarez, E.; Blundo, C.; Bunyavejchewin, S.; Chuyong, G.; Davies, S.J.; Duque, Á.; Ewango, C.N.; Flores, O.; Franklin, J.F.; Grau, H.R.; Hao, Z.; Harmon, M.E.; Hubbell, S.P.; Kenfack, D.; Lin, Y.; Makana, J.-R.; Malizia, A.; Malizia, L.R.; Pabst, R.J.; Pongpattananurak, N.; Su, S.-H.; Sun, I-F.; Tan, S.; Thomas, D.; van Mantgem, P.J.; Wang, X.; Wiser, S.K.; Zavala, M.A.

    2014-01-01

    Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest carbon cycle—particularly net primary productivity and carbon storage - increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute tree mass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age. Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree’s total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth, inform efforts to understand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence.

  4. Low carbon society scenario analysis of transport sector of an emerging economy—The AIM/Enduse modelling approach

    International Nuclear Information System (INIS)

    Selvakkumaran, Sujeetha; Limmeechokchai, Bundit

    2015-01-01

    The transport sector of a country is the backbone driving the economy forward. Thailand’s land transport sector is modelled using the AIM/Enduse, which is a recursive dynamic optimization model, based on bottom-up modelling principle. The travel demand is divided into two major categories which are passenger travel and freight travel. The objective of this paper is to analyse the mitigation possible through low carbon society (LCS) measures and emission tax (ET). Two scenario clusters are devised along with the BAU case. The LCS scenario cluster has three designed scenarios which are LCS-L, LCS-M and LCS-H. The emission tax (ET) cluster has four scenarios, where the taxes of 50, 100, 200 and 500 USD/t-CO 2 are implemented. Along with this the marginal abatement costs (MAC) of the counter-measures (CMs) and the co-benefits in terms of energy security, productivity and air pollutant mitigation are also assessed. Results show that LCS scenarios are possible of mitigating up to 1230 Mt-CO 2 cumulatively, from 2010 to 2050. In terms of MACs, new vehicles play a pivotal role, along with hybrid vehicles. The Average Abatement Cost (AAC) assessment shows that the AAC of LCS-H scenario is in the order of 100 USD/t-CO 2 . All the LCS and ET scenarios show an enhancement in energy security and also a threefold increase in productivity. There is distinct mitigation in terms of air pollutants from the transport sector as well. -- Highlights: •Thailand transport sector has been modelled using AIM/Enduse model. •Potential cumulative mitigation of CO 2 during 2010–2050 is approximately 30% when compared the BAU scenario. •Abatement cost curves show that various counter measures are practical in the transport sector. •Energy security is enhanced due to CO 2 mitigation in the LCS scenario

  5. Systolic trees and systolic language recognition by tree automata

    Energy Technology Data Exchange (ETDEWEB)

    Steinby, M

    1983-01-01

    K. Culik II, J. Gruska, A. Salomaa and D. Wood have studied the language recognition capabilities of certain types of systolically operating networks of processors (see research reports Cs-81-32, Cs-81-36 and Cs-82-01, Univ. of Waterloo, Ontario, Canada). In this paper, their model for systolic VLSI trees is formalised in terms of standard tree automaton theory, and the way in which some known facts about recognisable forests and tree transductions can be applied in VLSI tree theory is demonstrated. 13 references.

  6. An idealized model for tree-grass coexistence in savannas : The role of life stage structure and fire disturbances

    NARCIS (Netherlands)

    Baudena, Mara|info:eu-repo/dai/nl/340303867; D'Andrea, Fabio; Provenzale, A.

    2010-01-01

    1. We discuss a simple implicit-space model for the competition of trees and grasses in an idealized savanna environment. The model represents patch occupancy dynamics within the habitat and introduces life stage structure in the tree population, namely adults and seedlings. A tree can be

  7. Effects of species biological traits and environmental heterogeneity on simulated tree species distribution shifts under climate change.

    Science.gov (United States)

    Wang, Wen J; He, Hong S; Thompson, Frank R; Spetich, Martin A; Fraser, Jacob S

    2018-09-01

    Demographic processes (fecundity, dispersal, colonization, growth, and mortality) and their interactions with environmental changes are not well represented in current climate-distribution models (e.g., niche and biophysical process models) and constitute a large uncertainty in projections of future tree species distribution shifts. We investigate how species biological traits and environmental heterogeneity affect species distribution shifts. We used a species-specific, spatially explicit forest dynamic model LANDIS PRO, which incorporates site-scale tree species demography and competition, landscape-scale dispersal and disturbances, and regional-scale abiotic controls, to simulate the distribution shifts of four representative tree species with distinct biological traits in the central hardwood forest region of United States. Our results suggested that biological traits (e.g., dispersal capacity, maturation age) were important for determining tree species distribution shifts. Environmental heterogeneity, on average, reduced shift rates by 8% compared to perfect environmental conditions. The average distribution shift rates ranged from 24 to 200myear -1 under climate change scenarios, implying that many tree species may not able to keep up with climate change because of limited dispersal capacity, long generation time, and environmental heterogeneity. We suggest that climate-distribution models should include species demographic processes (e.g., fecundity, dispersal, colonization), biological traits (e.g., dispersal capacity, maturation age), and environmental heterogeneity (e.g., habitat fragmentation) to improve future predictions of species distribution shifts in response to changing climates. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Safety analyses of potential exposure in medical irradiation plants by Fuzzy Fault Tree

    International Nuclear Information System (INIS)

    Casamirra, Maddalena; Castiglia, Francesco; Giardina, Mariarosa; Tomarchio, Elio

    2008-01-01

    The results of Fuzzy Fault Tree (FFT) analyses of various accidental scenarios, which involve the operators in potential exposures inside an High Dose Rate (HDR) remote after-loading systems for use in brachytherapy, are reported. To carry out fault tree analyses by means of fuzzy probabilities, the TREEZZY2 computer code is used. Moreover, the HEART (Human Error Assessment and Reduction Technique) model, properly modified on the basis of the fuzzy approach, has been employed to assess the impact of performances haping and error-promoting factors in the context of the accidental events. The assessment of potential dose values for some identified accidental scenarios allows to consider, for a particular event, a fuzzy uncertainty range in potential dose estimate. The availability of lower and upper limits allows evaluating the possibility of optimization of the installation from the point of view of radiation protection. The adequacy of the training and information program for staff and patients (and their family members) and the effectiveness of behavioural rules and safety procedures were tested. Some recommendations on procedures and equipment to reduce the risk of radiological exposure are also provided. (author)

  9. An Assessment for A Filtered Containment Venting Strategy Using Decision Tree Models

    International Nuclear Information System (INIS)

    Shin, Hoyoung; Jae, Moosung

    2016-01-01

    In this study, a probabilistic assessment of the severe accident management strategy through a filtered containment venting system was performed by using decision tree models. In Korea, the filtered containment venting system has been installed for the first time in Wolsong unit 1 as a part of Fukushima follow-up steps, and it is planned to be applied gradually for all the remaining reactors. Filtered containment venting system, one of severe accident countermeasures, prevents a gradual pressurization of the containment building exhausting noncondensable gas and vapor to the outside of the containment building. In this study, a probabilistic assessment of the filtered containment venting strategy, one of the severe accident management strategies, was performed by using decision tree models. Containment failure frequencies of each decision were evaluated by the developed decision tree model. The optimum accident management strategies were evaluated by comparing the results. Various strategies in severe accident management guidelines (SAMG) could be improved by utilizing the methodology in this study and the offsite risk analysis methodology

  10. An Assessment for A Filtered Containment Venting Strategy Using Decision Tree Models

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Hoyoung; Jae, Moosung [Hanyang University, Seoul (Korea, Republic of)

    2016-10-15

    In this study, a probabilistic assessment of the severe accident management strategy through a filtered containment venting system was performed by using decision tree models. In Korea, the filtered containment venting system has been installed for the first time in Wolsong unit 1 as a part of Fukushima follow-up steps, and it is planned to be applied gradually for all the remaining reactors. Filtered containment venting system, one of severe accident countermeasures, prevents a gradual pressurization of the containment building exhausting noncondensable gas and vapor to the outside of the containment building. In this study, a probabilistic assessment of the filtered containment venting strategy, one of the severe accident management strategies, was performed by using decision tree models. Containment failure frequencies of each decision were evaluated by the developed decision tree model. The optimum accident management strategies were evaluated by comparing the results. Various strategies in severe accident management guidelines (SAMG) could be improved by utilizing the methodology in this study and the offsite risk analysis methodology.

  11. Protective Alternatives of SMR against Extreme Threat Scenario – A Preliminary Risk Analysis

    International Nuclear Information System (INIS)

    Shohet, I.M.; Ornai, D.; Gal, E.; Ronen, Y.; Vidra, M.

    2014-01-01

    The article presents a preliminary risk analysis of the main features in NPP (Nuclear Power Plant) that includes SMR - Small and Modular Reactors, given an extreme threat scenario. A review of the structure and systems of the SMR is followed by systematic definitions and analysis of the threat scenario to which a preliminary risk analysis was carried out. The article outlines the basic events caused by the referred threat scenario, which had led to possible failure mechanisms according to FTA (Fault-Tree-Analysis),critical protective circuits, and todetecting critical topics for the protection and safety of the reactor

  12. Coalescent methods for estimating phylogenetic trees.

    Science.gov (United States)

    Liu, Liang; Yu, Lili; Kubatko, Laura; Pearl, Dennis K; Edwards, Scott V

    2009-10-01

    We review recent models to estimate phylogenetic trees under the multispecies coalescent. Although the distinction between gene trees and species trees has come to the fore of phylogenetics, only recently have methods been developed that explicitly estimate species trees. Of the several factors that can cause gene tree heterogeneity and discordance with the species tree, deep coalescence due to random genetic drift in branches of the species tree has been modeled most thoroughly. Bayesian approaches to estimating species trees utilizes two likelihood functions, one of which has been widely used in traditional phylogenetics and involves the model of nucleotide substitution, and the second of which is less familiar to phylogeneticists and involves the probability distribution of gene trees given a species tree. Other recent parametric and nonparametric methods for estimating species trees involve parsimony criteria, summary statistics, supertree and consensus methods. Species tree approaches are an appropriate goal for systematics, appear to work well in some cases where concatenation can be misleading, and suggest that sampling many independent loci will be paramount. Such methods can also be challenging to implement because of the complexity of the models and computational time. In addition, further elaboration of the simplest of coalescent models will be required to incorporate commonly known issues such as deviation from the molecular clock, gene flow and other genetic forces.

  13. Development of a shortleaf pine individual-tree growth equation using non-linear mixed modeling techniques

    Science.gov (United States)

    Chakra B. Budhathoki; Thomas B. Lynch; James M. Guldin

    2010-01-01

    Nonlinear mixed-modeling methods were used to estimate parameters in an individual-tree basal area growth model for shortleaf pine (Pinus echinata Mill.). Shortleaf pine individual-tree growth data were available from over 200 permanently established 0.2-acre fixed-radius plots located in naturally-occurring even-aged shortleaf pine forests on the...

  14. Process based model sheds light on climate sensitivity of Mediterranean tree-ring width

    Directory of Open Access Journals (Sweden)

    R. Touchan

    2012-03-01

    Full Text Available We use the process-based VS (Vaganov-Shashkin model to investigate whether a regional Pinus halepensis tree-ring chronology from Tunisia can be simulated as a function of climate alone by employing a biological model linking day length and daily temperature and precipitation (AD 1959–2004 from a climate station to ring-width variations. We check performance of the model on independent data by a validation exercise in which the model's parameters are tuned using data for 1982–2004 and the model is applied to generate tree-ring indices for 1959–1981. The validation exercise yields a highly significant positive correlation between the residual chronology and estimated growth curve (r=0.76 p<0.0001, n=23. The model shows that the average duration of the growing season is 191 days, with considerable variation from year to year. On average, soil moisture limits tree-ring growth for 128 days and temperature for 63 days. Model results depend on chosen values of parameters, in particular a parameter specifying a balance ratio between soil moisture and precipitation. Future work in the Mediterranean region should include multi-year natural experiments to verify patterns of cambial-growth variation suggested by the VS model.

  15. Biosphere modelling for a HLW repository - scenario and parameter variations

    International Nuclear Information System (INIS)

    Grogan, H.

    1985-03-01

    In Switzerland high-level radioactive wastes have been considered for disposal in deep-lying crystalline formations. The individual doses to man resulting from radionuclides entering the biosphere via groundwater transport are calculated. The main recipient area modelled, which constitutes the base case, is a broad gravel terrace sited along the south bank of the river Rhine. An alternative recipient region, a small valley with a well, is also modelled. A number of parameter variations are performed in order to ascertain their impact on the doses. Finally two scenario changes are modelled somewhat simplistically, these consider different prevailing climates, namely tundra and a warmer climate than present. In the base case negligibly low doses to man in the long term, resulting from the existence of a HLW repository have been calculated. Cs-135 results in the largest dose (8.4E-7 mrem/y at 6.1E+6 y) while Np-237 gives the largest dose from the actinides (3.6E-8 mrem/y). The response of the model to parameter variations cannot be easily predicted due to non-linear coupling of many of the parameters. However, the calculated doses were negligibly low in all cases as were those resulting from the two scenario variations. (author)

  16. Developing scenarios to assess future landslide risks: a model-based approach applied to mountainous regions

    Science.gov (United States)

    Vacquie, Laure; Houet, Thomas

    2016-04-01

    In the last century, European mountain landscapes have experienced significant transformations. Natural and anthropogenic changes, climate changes, touristic and industrial development, socio-economic interactions, and their implications in terms of LUCC (land use and land cover changes) have directly influenced the spatial organization and vulnerability of mountain landscapes. This study is conducted as part of the SAMCO project founded by the French National Science Agency (ANR). It aims at developing a methodological approach, combining various tools, modelling platforms and methods, to identify vulnerable regions to landslide hazards accounting for futures LUCC. It presents an integrated approach combining participative scenarios and a LULC changes simulation models to assess the combined effects of LUCC and climate change on landslide risks in the Cauterets valley (French Pyrenees Mountains) up to 2100. Through vulnerability and risk mapping, the objective is to gather information to support landscape planning and implement land use strategies with local stakeholders for risk management. Four contrasting scenarios are developed and exhibit contrasting trajectories of socio-economic development. Prospective scenarios are based on national and international socio-economic contexts relying on existing assessment reports. The methodological approach integrates knowledge from local stakeholders to refine each scenario during their construction and to reinforce their plausibility and relevance by accounting for local specificities, e.g. logging and pastoral activities, touristic development, urban planning, etc. A process-based model, the Forecasting Scenarios for Mountains (ForeSceM) model, developed on the Dinamica Ego modelling platform is used to spatially allocate futures LUCC for each prospective scenario. Concurrently, a spatial decision support tool, i.e. the SYLVACCESS model, is used to identify accessible areas for forestry in scenario projecting logging

  17. Response of a multi-stressed Mediterranean river to future climate and socio-economic scenarios.

    Science.gov (United States)

    Stefanidis, Konstantinos; Panagopoulos, Yiannis; Mimikou, Maria

    2018-06-15

    Streams and rivers are among the most threatened ecosystems in Europe due to the combined effects of multiple pressures related to anthropogenic activities. Particularly in the Mediterranean region, changes in hydromorphology along with increased nutrient loadings are known to affect the ecological functions and ecosystem services of streams and rivers with the anticipated climate change being likely to further impair their functionality and structure. In this study, we investigated the combined effects of agricultural driven stressors on the ecology and delivered services of the Pinios river basin in Greece under three future world scenarios developed within the EU funded MARS project. Scenarios are based on combinations of Representative Concentration Pathways and Shared Socioeconomic Pathways and refer to early century (2030) and mid-century (2060) representing future climate worlds with particular socioeconomic characteristics. To assess the responses of ecological and ecosystem service indicators to the scenarios we first simulated hydrology and water quality in Pinios with a process-based model. Simulated abiotic stressor parameters (predictors) were linked to two biotic indicators, the macroinvertebrate indicators ASPT and EPT, with empirical modelling based on boosted regression trees and general linear models. Our results showed that the techno world scenario driven by fast economic growth and intensive exploitation of energy resources had the largest impact on both the abiotic status (nutrient loads and concentrations in water) and the biotic indicators. In contrast, the predicted changes under the other two future worlds, consensus and fragmented, were more diverse and were mostly dictated by the projected climate. This work showed that the future scenarios, especially the mid-century ones, had significant impact on both abiotic status and biotic responses underpinning the need for implementing catchment management practices able to mitigate the

  18. Comparing Two Different Approaches to the Modeling of the Common Cause Failures in Fault Trees

    International Nuclear Information System (INIS)

    Vukovic, I.; Mikulicic, V.; Vrbanic, I.

    2002-01-01

    The potential for common cause failures in systems that perform critical functions has been recognized as very important contributor to risk associated with operation of nuclear power plants. Consequentially, modeling of common cause failures (CCF) in fault trees has become one among the essential elements in any probabilistic safety assessment (PSA). Detailed and realistic representation of CCF potential in fault tree structure is sometimes very challenging task. This is especially so in the cases where a common cause group involves more than two components. During the last ten years the difficulties associated with this kind of modeling have been overcome to some degree by development of integral PSA tools with high capabilities. Some of them allow for the definition of CCF groups and their automated expanding in the process of Boolean resolution and generation of minimal cutsets. On the other hand, in PSA models developed and run by more traditional tools, CCF-potential had to be modeled in the fault trees explicitly. With explicit CCF modeling, fault trees can grow very large, especially in the cases when they involve CCF groups with 3 or more members, which can become an issue for the management of fault trees and basic events with traditional non-integral PSA models. For these reasons various simplifications had to be made. Speaking in terms of an overall PSA model, there are also some other issues that need to be considered, such as maintainability and accessibility of the model. In this paper a comparison is made between the two approaches to CCF modeling. Analysis is based on a full-scope Level 1 PSA model for internal initiating events that had originally been developed by a traditional PSA tool and later transferred to a new-generation PSA tool with automated CCF modeling capabilities. Related aspects and issues mentioned above are discussed in the paper. (author)

  19. Optimizing Water Allocation under Uncertain System Conditions for Water and Agriculture Future Scenarios in Alfeios River Basin (Greece—Part B: Fuzzy-Boundary Intervals Combined with Multi-Stage Stochastic Programming Model

    Directory of Open Access Journals (Sweden)

    Eleni Bekri

    2015-11-01

    Full Text Available Optimal water allocation within a river basin still remains a great modeling challenge for engineers due to various hydrosystem complexities, parameter uncertainties and their interactions. Conventional deterministic optimization approaches have given their place to stochastic, fuzzy and interval-parameter programming approaches and their hybrid combinations for overcoming these difficulties. In many countries, including Mediterranean countries, water resources management is characterized by uncertain, imprecise and limited data because of the absence of permanent measuring systems, inefficient river monitoring and fragmentation of authority responsibilities. A fuzzy-boundary-interval linear programming methodology developed by Li et al. (2010 is selected and applied in the Alfeios river basin (Greece for optimal water allocation under uncertain system conditions. This methodology combines an ordinary multi-stage stochastic programming with uncertainties expressed as fuzzy-boundary intervals. Upper- and lower-bound solution intervals for optimized water allocation targets and probabilistic water allocations and shortages are estimated under a baseline scenario and four water and agricultural policy future scenarios for an optimistic and a pessimistic attitude of the decision makers. In this work, the uncertainty of the random water inflows is incorporated through the simultaneous generation of stochastic equal-probability hydrologic scenarios at various inflow positions instead of using a scenario-tree approach in the original methodology.

  20. Tree Transduction Tools for Cdec

    Directory of Open Access Journals (Sweden)

    Austin Matthews

    2014-09-01

    Full Text Available We describe a collection of open source tools for learning tree-to-string and tree-to-tree transducers and the extensions to the cdec decoder that enable translation with these. Our modular, easy-to-extend tools extract rules from trees or forests aligned to strings and trees subject to different structural constraints. A fast, multithreaded implementation of the Cohn and Blunsom (2009 model for extracting compact tree-to-string rules is also included. The implementation of the tree composition algorithm used by cdec is described, and translation quality and decoding time results are presented. Our experimental results add to the body of evidence suggesting that tree transducers are a compelling option for translation, particularly when decoding speed and translation model size are important.

  1. Building interpretable predictive models for pediatric hospital readmission using Tree-Lasso logistic regression.

    Science.gov (United States)

    Jovanovic, Milos; Radovanovic, Sandro; Vukicevic, Milan; Van Poucke, Sven; Delibasic, Boris

    2016-09-01

    Quantification and early identification of unplanned readmission risk have the potential to improve the quality of care during hospitalization and after discharge. However, high dimensionality, sparsity, and class imbalance of electronic health data and the complexity of risk quantification, challenge the development of accurate predictive models. Predictive models require a certain level of interpretability in order to be applicable in real settings and create actionable insights. This paper aims to develop accurate and interpretable predictive models for readmission in a general pediatric patient population, by integrating a data-driven model (sparse logistic regression) and domain knowledge based on the international classification of diseases 9th-revision clinical modification (ICD-9-CM) hierarchy of diseases. Additionally, we propose a way to quantify the interpretability of a model and inspect the stability of alternative solutions. The analysis was conducted on >66,000 pediatric hospital discharge records from California, State Inpatient Databases, Healthcare Cost and Utilization Project between 2009 and 2011. We incorporated domain knowledge based on the ICD-9-CM hierarchy in a data driven, Tree-Lasso regularized logistic regression model, providing the framework for model interpretation. This approach was compared with traditional Lasso logistic regression resulting in models that are easier to interpret by fewer high-level diagnoses, with comparable prediction accuracy. The results revealed that the use of a Tree-Lasso model was as competitive in terms of accuracy (measured by area under the receiver operating characteristic curve-AUC) as the traditional Lasso logistic regression, but integration with the ICD-9-CM hierarchy of diseases provided more interpretable models in terms of high-level diagnoses. Additionally, interpretations of models are in accordance with existing medical understanding of pediatric readmission. Best performing models have

  2. Challenges of electricity production scenarios modelling for life cycle assessment of environmental impacts

    International Nuclear Information System (INIS)

    Blanc, Isabelle; Beloin-Saint-Pierre, Didier

    2013-01-01

    This communication presents a first attempt at making a life cycle assessment of prospective electricity production scenarios which were designed in the EnerGEO project. We start by a basic review of system (in this case, scenario) modelling expectations in today's LCA study. We then review some of the challenges of implementation due to the lack of detailed description of present and future electricity production systems. The importance of a detailed description is then shown with an evaluation of uncertainty of life cycle impact assessment results for three scenarios of German electricity production in 2030. The significant uncertainties we found, prevent us from detecting a relevant trend or making any comparison between the three chosen scenarios. We finally come to the conclusion that the LCA methodology will become relevant for the environmental assessment of electricity production scenarios when many more detailed information are accounted to describe future technologies, structures and sources of energy. (orig.)

  3. Challenges of electricity production scenarios modelling for life cycle assessment of environmental impacts

    Energy Technology Data Exchange (ETDEWEB)

    Blanc, Isabelle; Beloin-Saint-Pierre, Didier [MINES ParisTech, Sophia Antipolis (France). Observation, Impacts, Energy Center

    2013-07-01

    This communication presents a first attempt at making a life cycle assessment of prospective electricity production scenarios which were designed in the EnerGEO project. We start by a basic review of system (in this case, scenario) modelling expectations in today's LCA study. We then review some of the challenges of implementation due to the lack of detailed description of present and future electricity production systems. The importance of a detailed description is then shown with an evaluation of uncertainty of life cycle impact assessment results for three scenarios of German electricity production in 2030. The significant uncertainties we found, prevent us from detecting a relevant trend or making any comparison between the three chosen scenarios. We finally come to the conclusion that the LCA methodology will become relevant for the environmental assessment of electricity production scenarios when many more detailed information are accounted to describe future technologies, structures and sources of energy. (orig.)

  4. Potential recovery of industrial wood and energy wood raw material in different cutting and climate scenarios for Finland

    International Nuclear Information System (INIS)

    Kaerkkaeinen, Leena; Nuutinen, Tuula; Matala, Juho; Kellomaeki, Seppo; Haerkoenen, Kari

    2008-01-01

    The aim of this study was to estimate the simultaneous recovery of industrial wood and raw material for energy wood from cuttings in Finland during the next 50 years. Two cutting scenarios (maximum and sustainable cuttings) and two climate scenarios (current and changing climate) were analysed to determine their impacts on harvesting potential. The analysis was carried out using sample plot and tree data from the ninth National Forest Inventory and a management-oriented large-scale forestry model (MELA) into which the transfer functions based on physiological modelling were incorporated to describe the impacts of climate change. Depending on the climate scenario, the volume of potential recovery of industrial wood in the maximum cutting scenario during the period 2003-2013 varied from 103 to 105 million m 3 a -1 , while the amount of potential energy wood raw material was 35 Tg a -1 . During the period 2043-2053, in the current climate scenario, the potential recovery of industrial wood was 64 million m 3 a -1 and energy wood raw material 22 Tg a -1 , and in the changing climate scenario, 85 million m 3 a -1 and 29 Tg a -1 , respectively. In the sustainable cutting scenario, depending on the climate scenario used, the potential recovery of industrial wood during the period 2003-2013 varied from 74 to 76 million m 3 a -1 , while the amount of potential energy wood was 25 Tg a -1 . During the period 2043-2053, in the current climate scenario, the potential recovery of industrial wood was 80 million m 3 a -1 and energy wood raw material 26 Tg a -1 , and in the changing climate scenario, 88 million m 3 a -1 and 29 Tg a -1 , respectively. (author)

  5. Stochastic modelling of tree architecture and biomass allocation: application to teak (Tectona grandis L. f.), a tree species with polycyclic growth and leaf neoformation.

    Science.gov (United States)

    Tondjo, Kodjo; Brancheriau, Loïc; Sabatier, Sylvie; Kokutse, Adzo Dzifa; Kokou, Kouami; Jaeger, Marc; de Reffye, Philippe; Fourcaud, Thierry

    2018-06-08

    For a given genotype, the observed variability of tree forms results from the stochasticity of meristem functioning and from changing and heterogeneous environmental factors affecting biomass formation and allocation. In response to climate change, trees adapt their architecture by adjusting growth processes such as pre- and neoformation, as well as polycyclic growth. This is the case for the teak tree. The aim of this work was to adapt the plant model, GreenLab, in order to take into consideration both these processes using existing data on this tree species. This work adopted GreenLab formalism based on source-sink relationships at organ level that drive biomass production and partitioning within the whole plant over time. The stochastic aspect of phytomer production can be modelled by a Bernoulli process. The teak model was designed, parameterized and analysed using the architectural data from 2- to 5-year-old teak trees in open field stands. Growth and development parameters were identified, fitting the observed compound organic series with the theoretical series, using generalized least squares methods. Phytomer distributions of growth units and branching pattern varied depending on their axis category, i.e. their physiological age. These emerging properties were in accordance with the observed growth patterns and biomass allocation dynamics during a growing season marked by a short dry season. Annual growth patterns observed on teak, including shoot pre- and neoformation and polycyclism, were reproduced by the new version of the GreenLab model. However, further updating is discussed in order to ensure better consideration of radial variation in basic specific gravity of wood. Such upgrading of the model will enable teak ideotypes to be defined for improving wood production in terms of both volume and quality.

  6. Climate scenarios for California

    Science.gov (United States)

    Cayan, Daniel R.; Maurer, Ed; Dettinger, Mike; Tyree, Mary; Hayhoe, Katharine; Bonfils, Celine; Duffy, Phil; Santer, Ben

    2006-01-01

    Possible future climate changes in California are investigated from a varied set of climate change model simulations. These simulations, conducted by three state-of-the-art global climate models, provide trajectories from three greenhouse gas (GHG) emission scenarios. These scenarios and the resulting climate simulations are not “predictions,” but rather are a limited sample from among the many plausible pathways that may affect California’s climate. Future GHG concentrations are uncertain because they depend on future social, political, and technological pathways, and thus the IPCC has produced four “families” of emission scenarios. To explore some of these uncertainties, emissions scenarios A2 (a medium-high emissions) and B1 (low emissions) were selected from the current IPCC Fourth climate assessment, which provides several recent model simulations driven by A2 and B1 emissions. The global climate model simulations addressed here were from PCM1, the Parallel Climate Model from the National Center for Atmospheric Research (NCAR) and U.S. Department of Energy (DOE) group, and CM2.1 from the National Oceanic and Atmospheric Administration (NOAA) Geophysical Fluids Dynamics Laboratory (GFDL).

  7. Development of groundwater pesticide exposure modeling scenarios for vulnerable spring and winter wheat-growing areas.

    Science.gov (United States)

    Padilla, Lauren; Winchell, Michael; Peranginangin, Natalia; Grant, Shanique

    2017-11-01

    Wheat crops and the major wheat-growing regions of the United States are not included in the 6 crop- and region-specific scenarios developed by the US Environmental Protection Agency (USEPA) for exposure modeling with the Pesticide Root Zone Model conceptualized for groundwater (PRZM-GW). The present work augments the current scenarios by defining appropriately vulnerable PRZM-GW scenarios for high-producing spring and winter wheat-growing regions that are appropriate for use in refined pesticide exposure assessments. Initial screening-level modeling was conducted for all wheat areas across the conterminous United States as defined by multiple years of the Cropland Data Layer land-use data set. Soil, weather, groundwater temperature, evaporation depth, and crop growth and management practices were characterized for each wheat area from publicly and nationally available data sets and converted to input parameters for PRZM. Approximately 150 000 unique combinations of weather, soil, and input parameters were simulated with PRZM for an herbicide applied for postemergence weed control in wheat. The resulting postbreakthrough average herbicide concentrations in a theoretical shallow aquifer were ranked to identify states with the largest regions of relatively vulnerable wheat areas. For these states, input parameters resulting in near 90 th percentile postbreakthrough average concentrations corresponding to significant wheat areas with shallow depth to groundwater formed the basis for 4 new spring wheat scenarios and 4 new winter wheat scenarios to be used in PRZM-GW simulations. Spring wheat scenarios were identified in North Dakota, Montana, Washington, and Texas. Winter wheat scenarios were identified in Oklahoma, Texas, Kansas, and Colorado. Compared to the USEPA's original 6 scenarios, postbreakthrough average herbicide concentrations in the new scenarios were lower than all but Florida Potato and Georgia Coastal Peanuts of the original scenarios and better

  8. Identifiability of tree-child phylogenetic networks under a probabilistic recombination-mutation model of evolution.

    Science.gov (United States)

    Francis, Andrew; Moulton, Vincent

    2018-06-07

    Phylogenetic networks are an extension of phylogenetic trees which are used to represent evolutionary histories in which reticulation events (such as recombination and hybridization) have occurred. A central question for such networks is that of identifiability, which essentially asks under what circumstances can we reliably identify the phylogenetic network that gave rise to the observed data? Recently, identifiability results have appeared for networks relative to a model of sequence evolution that generalizes the standard Markov models used for phylogenetic trees. However, these results are quite limited in terms of the complexity of the networks that are considered. In this paper, by introducing an alternative probabilistic model for evolution along a network that is based on some ground-breaking work by Thatte for pedigrees, we are able to obtain an identifiability result for a much larger class of phylogenetic networks (essentially the class of so-called tree-child networks). To prove our main theorem, we derive some new results for identifying tree-child networks combinatorially, and then adapt some techniques developed by Thatte for pedigrees to show that our combinatorial results imply identifiability in the probabilistic setting. We hope that the introduction of our new model for networks could lead to new approaches to reliably construct phylogenetic networks. Copyright © 2018 Elsevier Ltd. All rights reserved.

  9. Learning from global emissions scenarios

    International Nuclear Information System (INIS)

    O'Neill, Brian C; Nakicenovic, Nebojsa

    2008-01-01

    Scenarios of global greenhouse gas emissions have played a key role in climate change analysis for over twenty years. Currently, several research communities are organizing to undertake a new round of scenario development in the lead-up to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). To help inform this process, we assess a number of past efforts to develop and learn from sets of global greenhouse gas emissions scenarios. We conclude that while emissions scenario exercises have likely had substantial benefits for participating modeling teams and produced insights from individual models, learning from the exercises taken as a whole has been more limited. Model comparison exercises have typically focused on the production of large numbers of scenarios while investing little in assessing the results or the production process, perhaps on the assumption that later assessment efforts could play this role. However, much of this assessment potential remains untapped. Efforts such as scenario-related chapters of IPCC reports have been most informative when they have gone to extra lengths to carry out more specific comparison exercises, but in general these assessments do not have the remit or resources to carry out the kind of detailed analysis of scenario results necessary for drawing the most useful conclusions. We recommend that scenario comparison exercises build-in time and resources for assessing scenario results in more detail at the time when they are produced, that these exercises focus on more specific questions to improve the prospects for learning, and that additional scenario assessments are carried out separately from production exercises. We also discuss the obstacles to better assessment that might exist, and how they might be overcome. Finally, we recommend that future work include much greater emphasis on understanding how scenarios are actually used, as a guide to improving scenario production.

  10. Modelling short-rotation coppice and tree planting for urban carbon management - a citywide analysis.

    Science.gov (United States)

    McHugh, Nicola; Edmondson, Jill L; Gaston, Kevin J; Leake, Jonathan R; O'Sullivan, Odhran S

    2015-10-01

    The capacity of urban areas to deliver provisioning ecosystem services is commonly overlooked and underutilized. Urban populations have globally increased fivefold since 1950, and they disproportionately consume ecosystem services and contribute to carbon emissions, highlighting the need to increase urban sustainability and reduce environmental impacts of urban dwellers. Here, we investigated the potential for increasing carbon sequestration, and biomass fuel production, by planting trees and short-rotation coppice (SRC), respectively, in a mid-sized UK city as a contribution to meeting national commitments to reduce CO 2 emissions.Iterative GIS models were developed using high-resolution spatial data. The models were applied to patches of public and privately owned urban greenspace suitable for planting trees and SRC, across the 73 km 2 area of the city of Leicester. We modelled tree planting with a species mix based on the existing tree populations, and SRC with willow and poplar to calculate biomass production in new trees, and carbon sequestration into harvested biomass over 25 years.An area of 11 km 2 comprising 15% of the city met criteria for tree planting and had the potential over 25 years to sequester 4200 tonnes of carbon above-ground. Of this area, 5·8 km 2 also met criteria for SRC planting and over the same period this could yield 71 800 tonnes of carbon in harvested biomass.The harvested biomass could supply energy to over 1566 domestic homes or 30 municipal buildings, resulting in avoided carbon emissions of 29 236 tonnes of carbon over 25 years when compared to heating by natural gas. Together with the net carbon sequestration into trees, a total reduction of 33 419 tonnes of carbon in the atmosphere could be achieved in 25 years by combined SRC and tree planting across the city. Synthesis and applications . We demonstrate that urban greenspaces in a typical UK city are underutilized for provisioning ecosystem services by trees and

  11. Probabilistic reasoning with graphical security models

    NARCIS (Netherlands)

    Kordy, Barbara; Pouly, Marc; Schweitzer, Patrick

    This work provides a computational framework for meaningful probabilistic evaluation of attack–defense scenarios involving dependent actions. We combine the graphical security modeling technique of attack–defense trees with probabilistic information expressed in terms of Bayesian networks. In order

  12. Tree manipulation experiment

    Science.gov (United States)

    Nishina, K.; Takenaka, C.; Ishizuka, S.; Hashimoto, S.; Yagai, Y.

    2012-12-01

    Some forest operations such as thinning and harvesting management could cause changes in N cycling and N2O emission from soils, since thinning and harvesting managements are accompanied with changes in aboveground environments such as an increase of slash falling and solar radiation on the forest floor. However, a considerable uncertainty exists in effects of thinning and harvesting on N2O fluxes regarding changes in belowground environments by cutting trees. To focus on the effect of changes in belowground environments on the N2O emissions from soils, we conducted a tree manipulation experiment in Japanese cedar (Cryptomeria japonica) stand without soil compaction and slash falling near the chambers and measured N2O flux at 50 cm and 150 cm distances from the tree trunk (stump) before and after cutting. We targeted 5 trees for the manipulation and established the measurement chambers to the 4 directions around each targeted tree relative to upper slope (upper, left, right, lower positions). We evaluated the effect of logging on the emission by using hierarchical Bayesian model. HB model can evaluate the variability in observed data and their uncertainties in the estimation with various probability distributions. Moreover, the HB model can easily accommodate the non-linear relationship among the N2O emissions and the environmental factors, and explicitly take non-independent data (nested structure of data) for the estimation into account by using random effects in the model. Our results showed tree cutting stimulated N2O emission from soils, and also that the increase of N2O flux depended on the distance from the trunk (stump): the increase of N2O flux at 50 cm from the trunk (stump) was greater than that of 150 cm from the trunk. The posterior simulation of the HB model indicated that the stimulation of N2O emission by tree cut- ting could reach up to 200 cm in our experimental plot. By tree cutting, the estimated N2O emission at 0-40 cm from the trunk doubled

  13. Social Foundation of Scenario Planning

    DEFF Research Database (Denmark)

    Rowland, Nicholas James; Spaniol, Matthew Jon

    2017-01-01

    In this article, the authors establish that models of scenario planning typically involve a series of phases, stages, or steps that imply a sequenced (i.e., linear or chronological) process. Recursive models, in contrast, allow phases to repeat, thus, incorporating iteration. The authors acknowle......In this article, the authors establish that models of scenario planning typically involve a series of phases, stages, or steps that imply a sequenced (i.e., linear or chronological) process. Recursive models, in contrast, allow phases to repeat, thus, incorporating iteration. The authors...... from science and technology studies (STS) on knowledge production, the authors explain transition from one phase to the next and iteration between and within phases based on social negotiation. To this end, the authors examine the interplay between the “scenario development” phase and the “scenario use......” phase of a planning process with a non-governmental organization in Denmark. The upshot for facilitators is practical insight into how transition between phases and phase iteration in scenario planning can be identified, leveraged, and, thus, managed. The upshot for scholars is a related insight...

  14. Capturing spiral radial growth of conifers using the superellipse to model tree-ring geometric shape.

    Science.gov (United States)

    Shi, Pei-Jian; Huang, Jian-Guo; Hui, Cang; Grissino-Mayer, Henri D; Tardif, Jacques C; Zhai, Li-Hong; Wang, Fu-Sheng; Li, Bai-Lian

    2015-01-01

    Tree-rings are often assumed to approximate a circular shape when estimating forest productivity and carbon dynamics. However, tree rings are rarely, if ever, circular, thereby possibly resulting in under- or over-estimation in forest productivity and carbon sequestration. Given the crucial role played by tree ring data in assessing forest productivity and carbon storage within a context of global change, it is particularly important that mathematical models adequately render cross-sectional area increment derived from tree rings. We modeled the geometric shape of tree rings using the superellipse equation and checked its validation based on the theoretical simulation and six actual cross sections collected from three conifers. We found that the superellipse better describes the geometric shape of tree rings than the circle commonly used. We showed that a spiral growth trend exists on the radial section over time, which might be closely related to spiral grain along the longitudinal axis. The superellipse generally had higher accuracy than the circle in predicting the basal area increment, resulting in an improved estimate for the basal area. The superellipse may allow better assessing forest productivity and carbon storage in terrestrial forest ecosystems.

  15. Risk modelling of shale gas development scenarios in the Central Karoo

    CSIR Research Space (South Africa)

    Schreiner, GO

    2018-06-01

    Full Text Available The scientific assessment of shale gas development was compiled by over 200 authors and peer reviewers from around the world. Novel assessment methods were used based on the concepts of risk, scenarios and predictive landscape modelling. Three...

  16. Modeling the global society-biosphere-climate system : Part 2: Computed scenarios

    NARCIS (Netherlands)

    Alcamo, J.; Van Den Born, G.J.; Bouwman, A.F.; De Haan, B.J.; Klein Goldewijk, K.; Klepper, O.; Krabec, J.; Leemans, R.; Olivier, J.G.J.; Toet, A.M.C.; De Vries, H.J.M.; Van Der Woerd, H.J.

    1994-01-01

    This paper presents scenarios computed with IMAGE 2.0, an integrated model of the global environment and climate change. Results are presented for selected aspects of the society-biosphere-climate system including primary energy consumption, emissions of various greenhouse gases, atmospheric

  17. Mean-field lattice trees

    NARCIS (Netherlands)

    Borgs, C.; Chayes, J.T.; Hofstad, van der R.W.; Slade, G.

    1999-01-01

    We introduce a mean-field model of lattice trees based on embeddings into d of abstract trees having a critical Poisson offspring distribution. This model provides a combinatorial interpretation for the self-consistent mean-field model introduced previously by Derbez and Slade [9], and provides an

  18. An analytical model of stand dynamics as a function of tree growth, mortality and recruitment: the shade tolerance-stand structure hypothesis revisited.

    Science.gov (United States)

    Zavala, Miguel A; Angulo, Oscar; Bravo de la Parra, Rafael; López-Marcos, Juan C

    2007-02-07

    Light competition and interspecific differences in shade tolerance are considered key determinants of forest stand structure and dynamics. Specifically two main stand diameter distribution types as a function of shade tolerance have been proposed based on empirical observations. All-aged stands of shade tolerant species tend to have steeply descending, monotonic diameter distributions (inverse J-shaped curves). Shade intolerant species in contrast typically exhibit normal (unimodal) tree diameter distributions due to high mortality rates of smaller suppressed trees. In this study we explore the generality of this hypothesis which implies a causal relationship between light competition or shade tolerance and stand structure. For this purpose we formulate a partial differential equation system of stand dynamics as a function of individual tree growth, recruitment and mortality which allows us to explore possible individual-based mechanisms--e.g. light competition-underlying observed patterns of stand structure--e.g. unimodal or inverse J-shaped equilibrium diameter curves. We find that contrary to expectations interspecific differences in growth patterns can result alone in any of the two diameter distributions types observed in the field. In particular, slow growing species can present unimodal equilibrium curves even in the absence of light competition. Moreover, light competition and shade intolerance evaluated both at the tree growth and mortality stages did not have a significant impact on stand structure that tended to converge systematically towards an inverse J-shaped curves for most tree growth scenarios. Realistic transient stand dynamics for even aged stands of shade intolerant species (unimodal curves) were only obtained when recruitment was completely suppressed, providing further evidence on the critical role played by juvenile stages of tree development (e.g. the sampling stage) on final forest structure and composition. The results also point out the

  19. Modelling Regional Climate Change Effects On Potential Natural Ecosystems in Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Koca, D.; Smith, B.; Sykes, M.T. [Centre for GeoBiosphere Science, Department of Physical Geography and Ecosystems Analysis, Lund University, Soelvegatan 12, S-223 62 Lund (Sweden)

    2006-10-15

    This study aims to demonstrate the potential of a process-based regional ecosystem model, LPJ-GUESS, driven by climate scenarios generated by a regional climate model system (RCM) to generate predictions useful for assessing effects of climatic and CO2 change on the key ecosystem services of carbon uptake and storage. Scenarios compatible with the A2 and B2 greenhouse gas emission scenarios of the Special Report on Emission Scenarios (SRES) and with boundary conditions from two general circulation models (GCMs) - HadAM3H and ECHAM4/OPYC3 - were used in simulations to explore changes in tree species distributions, vegetation structure, productivity and ecosystem carbon stocks for the late 21st Century, thus accommodating a proportion of the GCM-based and emissions-based uncertainty in future climate development. The simulations represented in this study were of the potential natural vegetation ignoring direct anthropogenic effects. Results suggest that shifts in climatic zones may lead to changes in species distribution and community composition among seven major tree species of natural Swedish forests. All four climate scenarios were associated with an extension of the boreal forest treeline with respect to altitude and latitude. In the boreal and boreo-nemoral zones, the dominance of Norway spruce and to a lesser extent Scots pine was reduced in favour of deciduous broadleaved tree species. The model also predicted substantial increases in vegetation net primary productivity (NPP), especially in central Sweden. Expansion of forest cover and increased local biomass enhanced the net carbon sink over central and northern Sweden, despite increased carbon release through decomposition processes in the soil. In southern Sweden, reduced growing season soil moisture levels counterbalanced the positive effects of a longer growing season and increased carbon supply on NPP, with the result that many areas were converted from a sink to a source of carbon by the late 21st

  20. Modelling Regional Climate Change Effects On Potential Natural Ecosystems in Sweden

    International Nuclear Information System (INIS)

    Koca, D.; Smith, B.; Sykes, M.T.

    2006-01-01

    This study aims to demonstrate the potential of a process-based regional ecosystem model, LPJ-GUESS, driven by climate scenarios generated by a regional climate model system (RCM) to generate predictions useful for assessing effects of climatic and CO2 change on the key ecosystem services of carbon uptake and storage. Scenarios compatible with the A2 and B2 greenhouse gas emission scenarios of the Special Report on Emission Scenarios (SRES) and with boundary conditions from two general circulation models (GCMs) - HadAM3H and ECHAM4/OPYC3 - were used in simulations to explore changes in tree species distributions, vegetation structure, productivity and ecosystem carbon stocks for the late 21st Century, thus accommodating a proportion of the GCM-based and emissions-based uncertainty in future climate development. The simulations represented in this study were of the potential natural vegetation ignoring direct anthropogenic effects. Results suggest that shifts in climatic zones may lead to changes in species distribution and community composition among seven major tree species of natural Swedish forests. All four climate scenarios were associated with an extension of the boreal forest treeline with respect to altitude and latitude. In the boreal and boreo-nemoral zones, the dominance of Norway spruce and to a lesser extent Scots pine was reduced in favour of deciduous broadleaved tree species. The model also predicted substantial increases in vegetation net primary productivity (NPP), especially in central Sweden. Expansion of forest cover and increased local biomass enhanced the net carbon sink over central and northern Sweden, despite increased carbon release through decomposition processes in the soil. In southern Sweden, reduced growing season soil moisture levels counterbalanced the positive effects of a longer growing season and increased carbon supply on NPP, with the result that many areas were converted from a sink to a source of carbon by the late 21st

  1. Evaluating adaptation options for urban flooding based on new high-end emission scenario regional climate model simulations

    DEFF Research Database (Denmark)

    Arnbjerg-Nielsen, Karsten; Leonardsen, L.; Madsen, Henrik

    2015-01-01

    Climate change adaptation studies on urban flooding are often based on a model chain approach from climate forcing scenarios to analysis of adaptation measures. Previous analyses of climate change impacts in Copenhagen, Denmark, were supplemented by 2 high-end scenario simulations. These include...... a regional climate model projection forced to a global temperature increase of 6 degrees C in 2100 as well as a projection based on a high radiative forcing scenario (RCP8.5). With these scenarios, projected impacts of extreme precipitation increase significantly. For extreme sea surges, the impacts do...... by almost 4 and 8 times the current EAD for the RCP8.5 and 6 degrees C scenario, respectively. For both hazards, business-as-usual is not a possible scenario, since even in the absence of policy-driven changes, significant autonomous adaptation is likely to occur. Copenhagen has developed an adaptation plan...

  2. Tree growth visualization

    Science.gov (United States)

    L. Linsen; B.J. Karis; E.G. McPherson; B. Hamann

    2005-01-01

    In computer graphics, models describing the fractal branching structure of trees typically exploit the modularity of tree structures. The models are based on local production rules, which are applied iteratively and simultaneously to create a complex branching system. The objective is to generate three-dimensional scenes of often many realistic- looking and non-...

  3. A passive cold storage device economic model to evaluate selected immunization location scenarios.

    Science.gov (United States)

    Norman, Bryan A; Nourollahi, Sevnaz; Chen, Sheng-I; Brown, Shawn T; Claypool, Erin G; Connor, Diana L; Schmitz, Michelle M; Rajgopal, Jayant; Wateska, Angela R; Lee, Bruce Y

    2013-10-25

    The challenge of keeping vaccines cold at health posts given the unreliability of power sources in many low- and middle-income countries and the expense and maintenance requirements of solar refrigerators has motivated the development of passive cold storage devices (PCDs), containers that keep vaccines cold without using an active energy source. With different PCDs under development, manufacturers, policymakers and funders need guidance on how varying different PCD characteristics may affect the devices' cost and utility. We developed an economic spreadsheet model representing the lowest two levels of a typical Expanded Program on Immunization (EPI) vaccine supply chain: a district store, the immunization locations that the district store serves, and the transport vehicles that operate between the district store and the immunization locations. The model compares the use of three vaccine storage device options [(1) portable PCDs, (2) stationary PCDs, or (3) solar refrigerators] and allows the user to vary different device (e.g., size and cost) and scenario characteristics (e.g., catchment area population size and vaccine schedule). For a sample set of select scenarios and equipment specification, we found the portable PCD to generally be better suited to populations of 5,000 or less. The stationary PCD replenished once per month can be a robust design especially with a 35L capacity and a cost of $2,500 or less. The solar device was generally a reasonable alternative for most of the scenarios explored if the cost was $2,100 or less (including installation). No one device type dominated over all explored circumstances. Therefore, the best device may vary from country-to-country and location-to-location within a country. This study introduces a quantitative model to help guide PCD development. Although our selected set of explored scenarios and device designs was not exhaustive, future explorations can further alter model input values to represent additional scenarios

  4. Postprocessing of Accidental Scenarios by Semi-Supervised Self-Organizing Maps

    Directory of Open Access Journals (Sweden)

    Francesco Di Maio

    2017-01-01

    Full Text Available Integrated Deterministic and Probabilistic Safety Analysis (IDPSA of dynamic systems calls for the development of efficient methods for accidental scenarios generation. The necessary consideration of failure events timing and sequencing along the scenarios requires the number of scenarios to be generated to increase with respect to conventional PSA. Consequently, their postprocessing for retrieving safety relevant information regarding the system behavior is challenged because of the large amount of generated scenarios that makes the computational cost for scenario postprocessing enormous and the retrieved information difficult to interpret. In the context of IDPSA, the interpretation consists in the classification of the generated scenarios as safe, failed, Near Misses (NMs, and Prime Implicants (PIs. To address this issue, in this paper we propose the use of an ensemble of Semi-Supervised Self-Organizing Maps (SSSOMs whose outcomes are combined by a locally weighted aggregation according to two strategies: a locally weighted aggregation and a decision tree based aggregation. In the former, we resort to the Local Fusion (LF principle for accounting the classification reliability of the different SSSOM classifiers, whereas in the latter we build a classification scheme to select the appropriate classifier (or ensemble of classifiers, for the type of scenario to be classified. The two strategies are applied for the postprocessing of the accidental scenarios of a dynamic U-Tube Steam Generator (UTSG.

  5. Perceived Organizational Support for Enhancing Welfare at Work: A Regression Tree Model

    Science.gov (United States)

    Giorgi, Gabriele; Dubin, David; Perez, Javier Fiz

    2016-01-01

    When trying to examine outcomes such as welfare and well-being, research tends to focus on main effects and take into account limited numbers of variables at a time. There are a number of techniques that may help address this problem. For example, many statistical packages available in R provide easy-to-use methods of modeling complicated analysis such as classification and tree regression (i.e., recursive partitioning). The present research illustrates the value of recursive partitioning in the prediction of perceived organizational support in a sample of more than 6000 Italian bankers. Utilizing the tree function party package in R, we estimated a regression tree model predicting perceived organizational support from a multitude of job characteristics including job demand, lack of job control, lack of supervisor support, training, etc. The resulting model appears particularly helpful in pointing out several interactions in the prediction of perceived organizational support. In particular, training is the dominant factor. Another dimension that seems to influence organizational support is reporting (perceived communication about safety and stress concerns). Results are discussed from a theoretical and methodological point of view. PMID:28082924

  6. Why do trees die? Characterizing the drivers of background tree mortality

    Science.gov (United States)

    Das, Adrian J.; Stephenson, Nathan L.; Davis, Kristin P.

    2016-01-01

    The drivers of background tree mortality rates—the typical low rates of tree mortality found in forests in the absence of acute stresses like drought—are central to our understanding of forest dynamics, the effects of ongoing environmental changes on forests, and the causes and consequences of geographical gradients in the nature and strength of biotic interactions. To shed light on factors contributing to background tree mortality, we analyzed detailed pathological data from 200,668 tree-years of observation and 3,729 individual tree deaths, recorded over a 13-yr period in a network of old-growth forest plots in California's Sierra Nevada mountain range. We found that: (1) Biotic mortality factors (mostly insects and pathogens) dominated (58%), particularly in larger trees (86%). Bark beetles were the most prevalent (40%), even though there were no outbreaks during the study period; in contrast, the contribution of defoliators was negligible. (2) Relative occurrences of broad classes of mortality factors (biotic, 58%; suppression, 51%; and mechanical, 25%) are similar among tree taxa, but may vary with tree size and growth rate. (3) We found little evidence of distinct groups of mortality factors that predictably occur together on trees. Our results have at least three sets of implications. First, rather than being driven by abiotic factors such as lightning or windstorms, the “ambient” or “random” background mortality that many forest models presume to be independent of tree growth rate is instead dominated by biotic agents of tree mortality, with potentially critical implications for forecasting future mortality. Mechanistic models of background mortality, even for healthy, rapidly growing trees, must therefore include the insects and pathogens that kill trees. Second, the biotic agents of tree mortality, instead of occurring in a few predictable combinations, may generally act opportunistically and with a relatively large degree of independence from

  7. An Integrated Approach of Model checking and Temporal Fault Tree for System Safety Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Kwang Yong; Seong, Poong Hyun [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2009-10-15

    Digitalization of instruments and control systems in nuclear power plants offers the potential to improve plant safety and reliability through features such as increased hardware reliability and stability, and improved failure detection capability. It however makes the systems and their safety analysis more complex. Originally, safety analysis was applied to hardware system components and formal methods mainly to software. For software-controlled or digitalized systems, it is necessary to integrate both. Fault tree analysis (FTA) which has been one of the most widely used safety analysis technique in nuclear industry suffers from several drawbacks as described in. In this work, to resolve the problems, FTA and model checking are integrated to provide formal, automated and qualitative assistance to informal and/or quantitative safety analysis. Our approach proposes to build a formal model of the system together with fault trees. We introduce several temporal gates based on timed computational tree logic (TCTL) to capture absolute time behaviors of the system and to give concrete semantics to fault tree gates to reduce errors during the analysis, and use model checking technique to automate the reasoning process of FTA.

  8. Investigation of an artificial intelligence technology--Model trees. Novel applications for an immediate release tablet formulation database.

    Science.gov (United States)

    Shao, Q; Rowe, R C; York, P

    2007-06-01

    This study has investigated an artificial intelligence technology - model trees - as a modelling tool applied to an immediate release tablet formulation database. The modelling performance was compared with artificial neural networks that have been well established and widely applied in the pharmaceutical product formulation fields. The predictability of generated models was validated on unseen data and judged by correlation coefficient R(2). Output from the model tree analyses produced multivariate linear equations which predicted tablet tensile strength, disintegration time, and drug dissolution profiles of similar quality to neural network models. However, additional and valuable knowledge hidden in the formulation database was extracted from these equations. It is concluded that, as a transparent technology, model trees are useful tools to formulators.

  9. Reuse-centric Requirements Analysis with Task Models, Scenarios, and Critical Parameters

    Directory of Open Access Journals (Sweden)

    Cyril Montabert

    2007-02-01

    Full Text Available This paper outlines a requirements-analysis process that unites task models, scenarios, and critical parameters to exploit and generate reusable knowledge at the requirements phase. Through the deployment of a critical-parameter-based approach to task modeling, the process yields the establishment of an integrative and formalized model issued from scenarios that can be used for requirements characterization. Furthermore, not only can this entity serve as interface to a knowledge repository relying on a critical-parameter-based taxonomy to support reuse but its characterization in terms of critical parameters also allows the model to constitute a broader reuse solution. We discuss our vision for a user-centric and reuse-centric approach to requirements analysis, present previous efforts implicated with this line of work, and state the revisions brought to extend the reuse potential and effectiveness of a previous iteration of a requirements tool implementing such process. Finally, the paper describes the sequence and nature of the activities involved with the conduct of our proposed requirements-analysis technique, concluding by previewing ongoing work in the field that will explore the feasibility for designers to use our approach.

  10. Propagation Path Loss Models for 5G Urban Micro- and Macro-Cellular Scenarios

    DEFF Research Database (Denmark)

    Sun, Shu; Rappaport, Theodore S.; Rangan, Sundeep

    2016-01-01

    This paper presents and compares two candidate large-scale propagation path loss models, the alpha-beta-gamma (ABG) model and the close-in (CI) free space reference distance model, for the design of fifth generation (5G) wireless communication systems in urban micro- and macro-cellular scenarios....

  11. Flat tree-level inflationary potentials in the light of cosmic microwave background and large scale structure data

    CERN Document Server

    Ballesteros, G; Espinosa, J R; de Austri, R Ruiz; Trotta, R

    2008-01-01

    We use cosmic microwave background and large scale structure data to test a broad and physically well-motivated class of inflationary models: those with flat tree-level potentials (typical in supersymmetry). The non-trivial features of the potential arise from radiative corrections which give a simple logarithmic dependence on the inflaton field, making the models very predictive. We also consider a modified scenario with new physics beyond a certain high-energy cut-off showing up as non-renormalizable operators (NRO) in the inflaton field. We find that both kinds of models fit remarkably well CMB and LSS data, with very few free parameters. Besides, a large part of these models naturally predict a reasonable number of e-folds. A robust feature of these scenarios is the smallness of tensor perturbations (r < 10^{-3}). The NRO case can give a sizeable running of the spectral index while achieving a sufficient number of e-folds. We use Bayesian model comparison tools to assess the relative performance of the...

  12. Trees in the city: valuing street trees in Portland, Oregon

    Science.gov (United States)

    G.H. Donovan; D.T. Butry

    2010-01-01

    We use a hedonic price model to simultaneously estimate the effects of street trees on the sales price and the time-on-market (TOM) of houses in Portland. Oregon. On average, street trees add $8,870 to sales price and reduce TOM by 1.7 days. In addition, we found that the benefits of street trees spill over to neighboring houses. Because the provision and maintenance...

  13. Modeling Trees with a Space Colonization Algorithm

    OpenAIRE

    Morell Higueras, Marc

    2014-01-01

    [CATALÀ] Aquest TFG tracta la implementació d'un algorisme de generació procedural que construeixi una estructura reminiscent a la d'un arbre de clima temperat, i també la implementació del pas de l'estructura a un model tridimensional, acompanyat de l'eina per a visualitzar el resultat i fer-ne l'exportació [ANGLÈS] This TFG consists of the implementation of a procedural generation algorithm that builds a structure reminiscent of that of a temperate climate tree, and also consists of the ...

  14. Meteorological Factors and Tree Characteristics Influencing the Initiation and Rate of Stemflow from Deciduous Trees in an Urban Park

    Science.gov (United States)

    Schooling, J. T.; Carlyle-Moses, D. E.

    2013-12-01

    Stemflow, SF, represents that portion of precipitation that is intercepted by a tree's canopy and diverted to the ground at the tree base by flowing along branches and down the bole. The focused input of water and nutrients associated with SF have been shown to be of hydrological and biogeochemical importance in a number of plant communities and forest environments. Although the concentrated water volume and the nutrient / pollutant fluxes associated with SF in urban areas may be highly relevant for stormwater quantity and quality management, they have received only minor study in built environments. In an urban park in Kamloops, British Columbia, Canada, SF volumes generated from 40 deciduous trees representing 22 species were sampled on a precipitation event basis over a period of 16 months. Using this data, we derived the threshold rainfall depth required for SF initiation from each tree by taking the absolute value of the y-intercept of the linear regression of SF volume versus rainfall depth divided by the slope of that regression. The SF discharge rate once the threshold rainfall depth had been reached was taken as the slope of the linear regression equation. Thus, a simplified SF equation was developed: SFv = QSF x (Pg = Pg''), where SFv is stemflow volume (litres), QSF is the discharge rate (litres / mm), and Pg and Pg' represent the precipitation depth and the threshold precipitation depth, respectively. We then examined the influence of meteorological factors (precipitation type [rain / snow / rain + snow], precipitation depth, rainfall intensity, wind speed and direction, and vapour pressure deficit), and tree characteristics (tree diameter at breast height, tree height, leaf size and orientation, bark roughness, crown projection area, leaf area index, canopy cover fraction, branching angle, the proportion of the crown that was comprised of branches, and overlap with other tree canopies) on QSF and Pg' in order to expand on the simplified model and

  15. Optimization Method of Fusing Model Tree into Partial Least Squares

    Directory of Open Access Journals (Sweden)

    Yu Fang

    2017-01-01

    Full Text Available Partial Least Square (PLS can’t adapt to the characteristics of the data of many fields due to its own features multiple independent variables, multi-dependent variables and non-linear. However, Model Tree (MT has a good adaptability to nonlinear function, which is made up of many multiple linear segments. Based on this, a new method combining PLS and MT to analysis and predict the data is proposed, which build MT through the main ingredient and the explanatory variables(the dependent variable extracted from PLS, and extract residual information constantly to build Model Tree until well-pleased accuracy condition is satisfied. Using the data of the maxingshigan decoction of the monarch drug to treat the asthma or cough and two sample sets in the UCI Machine Learning Repository, the experimental results show that, the ability of explanation and predicting get improved in the new method.

  16. How disturbance, competition, and dispersal interact to prevent tree range boundaries from keeping pace with climate change.

    Science.gov (United States)

    Liang, Yu; Duveneck, Matthew J; Gustafson, Eric J; Serra-Diaz, Josep M; Thompson, Jonathan R

    2018-01-01

    Climate change is expected to cause geographic shifts in tree species' ranges, but such shifts may not keep pace with climate changes because seed dispersal distances are often limited and competition-induced changes in community composition can be relatively slow. Disturbances may speed changes in community composition, but the interactions among climate change, disturbance and competitive interactions to produce range shifts are poorly understood. We used a physiologically based mechanistic landscape model to study these interactions in the northeastern United States. We designed a series of disturbance scenarios to represent varied disturbance regimes in terms of both disturbance extent and intensity. We simulated forest succession by incorporating climate change under a high-emissions future, disturbances, seed dispersal, and competition using the landscape model parameterized with forest inventory data. Tree species range boundary shifts in the next century were quantified as the change in the location of the 5th (the trailing edge) and 95th (the leading edge) percentiles of the spatial distribution of simulated species. Simulated tree species range boundary shifts in New England over the next century were far below (usually change (usually more than 110 km over 100 years) under a high-emissions scenario. Simulated species` ranges shifted northward at both the leading edge (northern boundary) and trailing edge (southern boundary). Disturbances may expedite species' recruitment into new sites, but they had little effect on the velocity of simulated range boundary shifts. Range shifts at the trailing edge tended to be associated with photosynthetic capacity, competitive ability for light and seed dispersal ability, whereas shifts at the leading edge were associated only with photosynthetic capacity and competition for light. This study underscores the importance of understanding the role of interspecific competition and disturbance when studying tree range

  17. LINEAR MIXED MODEL TO DESCRIBE THE BASAL AREA INCREMENT FOR INDIVUDUAL CEDRO (Cedrela odorata L.TREES IN OCCIDENTAL AMAZON, BRAZIL

    Directory of Open Access Journals (Sweden)

    Thiago Augusto da Cunha

    2013-01-01

    Full Text Available Reliable growth data from trees are important to establish a rational forest management. Characteristics from trees, like the size, crown architecture and competition indices have been used to mathematically describe the increment efficiently when associated with them. However, the precise role of these effects in the growth-modeling destined to tropical trees needs to be further studied. Here it is reconstructed the basal area increment (BAI of individual Cedrela odorata trees, sampled at Amazon forest, to develop a growth- model using potential-predictors like: (1 classical tree size; (2 morphometric data; (3 competition and (4 social position including liana loads. Despite the large variation in tree size and growth, we observed that these kinds of predictor variables described well the BAI in level of individual tree. The fitted mixed model achieve a high efficiency (R2=92.7 % and predicted 3-years BAI over bark for trees of Cedrela odorata ranging from 10 to 110 cm at diameter at breast height. Tree height, steam slenderness and crown formal demonstrated high influence in the BAI growth model and explaining most of the growth variance (Partial R2=87.2%. Competition variables had negative influence on the BAI, however, explained about 7% of the total variation. The introduction of a random parameter on the regressions model (mixed modelprocedure has demonstrated a better significance approach to the data observed and showed more realistic predictions than the fixed model.

  18. Interspecific variation in tree seedlings establishment in canopy gaps in relation to tree density

    Energy Technology Data Exchange (ETDEWEB)

    Reader, R.J.; Bonser, S.P.; Duralia, T.E.; Bricker, B.D. [Guelph Univ., ON (Canada). Dept. of Botany

    1995-10-01

    We tested whether interspecific variation in tree seedling establishment in canopy gaps was significantly related to interspecific variation in tree density, for seven deciduous forest tree species (Quercus alba, Hamamelis virginiana, Acer rubrum, Sassafras albidum, Quercus rubra, Prunus serotina, Ostrya virginiana). For each species, seedling establishment was calculated as the difference in seedling density before experimental gap creation versus three years after gap creation. In each of the six experimentally-created gap types (33% or 66% removal of tree basal area from 0.01ha, 0.05ha or 0.20ha patches), differences in seedling establishment among species were significantly related to differences in their density in the tree canopy. A regression model with log{sub e} tree density as the independent variable accounted for between 93% and 98% of interspecific variation in seedling establishment. Our results provide empirical support for models of tree dynamics in gaps that assume seedling establishment depends on canopy tree density. 17 refs, 1 fig, 3 tabs

  19. A Generalized Deforestation and Land-Use Change Scenario Generator for Use in Climate Modelling Studies

    Science.gov (United States)

    Tompkins, Adrian Mark; Caporaso, Luca; Biondi, Riccardo; Bell, Jean Pierre

    2015-01-01

    A new deforestation and land-use change scenario generator model (FOREST-SAGE) is presented that is designed to interface directly with dynamic vegetation models used in latest generation earth system models. The model requires a regional-scale scenario for aggregate land-use change that may be time-dependent, provided by observational studies or by regional land-use change/economic models for future projections. These land-use categories of the observations/economic model are first translated into equivalent plant function types used by the particular vegetation model, and then FOREST-SAGE disaggregates the regional-scale scenario to the local grid-scale of the earth system model using a set of risk-rules based on factors such as proximity to transport networks, distance weighted population density, forest fragmentation and presence of protected areas and logging concessions. These rules presently focus on the conversion of forest to agriculture and pasture use, but could be generalized to other land use change conversions. After introducing the model, an evaluation of its performance is shown for the land-cover changes that have occurred in the Central African Basin from 2001–2010 using retrievals from MODerate Resolution Imaging Spectroradiometer Vegetation Continuous Field data. The model is able to broadly reproduce the spatial patterns of forest cover change observed by MODIS, and the use of the local-scale risk factors enables FOREST-SAGE to improve land use change patterns considerably relative to benchmark scenarios used in the latest Coupled Model Intercomparison Project integrations. The uncertainty to the various risk factors is investigated using an ensemble of investigations, and it is shown that the model is sensitive to the population density, forest fragmentation and reforestation factors specified. PMID:26394392

  20. Assessment of nuclear power scenarios allowing for matrix behavior in radiological impact modeling of disposal scenarios

    International Nuclear Information System (INIS)

    Tronche, E.; Boussier, H.

    2000-01-01

    Under the provisions of the 1991 French radioactive waste management law, various fuel cycle scenarios will be assessed and compared in terms of feasibility, flexibility, cost, and ultimate waste radio-toxic inventory. The latter criterion may be further broken down into 'potential radio-toxic inventory' (the radio-toxic inventory of all the radionuclides produced) and 'residual radio-toxic inventory' (the radionuclide fraction reaching the biosphere after migration from the repository). The innovative scientific contribution of this study is to consider a third type of radio-toxic inventory: the potential radio-toxic inventory after conditioning, i.e. taking into account the containment capacity of the radionuclide conditioning matrices. The matrix fraction subjected to alteration over time determines the potential for radionuclide release, hence the notion of the potential radio-toxic inventory after conditioning. An initial comparison of possible scenarios is proposed by considering orders of magnitude for the radionuclide containment capacity of the disposal matrices and for their mobilization potential. All the scenarios investigated are normalized to the same annual electric power production so that a legitimate comparison can be established for the ultimate wasteform produced per year of operation. This approach reveals significant differences among the scenarios considered that do not appear when only the raw potential radio-toxic inventory is taken into account. The matrix containment performance has a decisive effect on the final impact of a given scenario or type of scenario. Pu recycling scenarios thus reduce the potential radio-toxicity by roughly a factor of 50 compared with an open cycle; the gain rises to a factor of about 300 for scenarios in which Pu and the minor actinides are recycled. Interestingly, the results obtained by the use of a dedicated containment matrix for the minor actinides in a scenario limited to Pu recycling were comparable to

  1. Monitoring Million Trees LA: Tree performance during the early years and future benefits

    Science.gov (United States)

    E. Gregory McPherson

    2014-01-01

    Million Trees LA (MTLA) is one of several large-scale mayoral tree planting initiatives striving to create more livable cities through urban forestry. This study combined field sampling of tree survival and growth with numerical modeling of future benefits to assess performance of MTLA plantings. From 2006 to 2010 MTLA planted a diverse mix of 91,786 trees....

  2. TreeNetViz: revealing patterns of networks over tree structures.

    Science.gov (United States)

    Gou, Liang; Zhang, Xiaolong Luke

    2011-12-01

    Network data often contain important attributes from various dimensions such as social affiliations and areas of expertise in a social network. If such attributes exhibit a tree structure, visualizing a compound graph consisting of tree and network structures becomes complicated. How to visually reveal patterns of a network over a tree has not been fully studied. In this paper, we propose a compound graph model, TreeNet, to support visualization and analysis of a network at multiple levels of aggregation over a tree. We also present a visualization design, TreeNetViz, to offer the multiscale and cross-scale exploration and interaction of a TreeNet graph. TreeNetViz uses a Radial, Space-Filling (RSF) visualization to represent the tree structure, a circle layout with novel optimization to show aggregated networks derived from TreeNet, and an edge bundling technique to reduce visual complexity. Our circular layout algorithm reduces both total edge-crossings and edge length and also considers hierarchical structure constraints and edge weight in a TreeNet graph. These experiments illustrate that the algorithm can reduce visual cluttering in TreeNet graphs. Our case study also shows that TreeNetViz has the potential to support the analysis of a compound graph by revealing multiscale and cross-scale network patterns. © 2011 IEEE

  3. Impact modelling of water resources development and climate scenarios on Zambezi River discharge

    Directory of Open Access Journals (Sweden)

    Harald Kling

    2014-07-01

    New hydrological insights for the region: Comparisons between historical and future scenarios show that the biggest changes have already occurred. Construction of Kariba and CahoraBassa dams in the mid 1900s altered the seasonality and flow duration curves. Future irrigation development will cause decreases of a similar magnitude to those caused by current reservoir evaporation losses. The discharge is highly sensitive to small precipitation changes and the two climate models used give different signs for future precipitation change, suggestive of large uncertainty. The river basin model and database are available as anopen-online Decision Support System to facilitate impact assessments of additional climate or development scenarios.

  4. Map-Based Channel Model for Urban Macrocell Propagation Scenarios

    Directory of Open Access Journals (Sweden)

    Jose F. Monserrat

    2015-01-01

    Full Text Available The evolution of LTE towards 5G has started and different research projects and institutions are in the process of verifying new technology components through simulations. Coordination between groups is strongly recommended and, in this sense, a common definition of test cases and simulation models is needed. The scope of this paper is to present a realistic channel model for urban macrocell scenarios. This model is map-based and takes into account the layout of buildings situated in the area under study. A detailed description of the model is given together with a comparison with other widely used channel models. The benchmark includes a measurement campaign in which the proposed model is shown to be much closer to the actual behavior of a cellular system. Particular attention is given to the outdoor component of the model, since it is here where the proposed approach is showing main difference with other previous models.

  5. Phylogenetic trees

    OpenAIRE

    Baños, Hector; Bushek, Nathaniel; Davidson, Ruth; Gross, Elizabeth; Harris, Pamela E.; Krone, Robert; Long, Colby; Stewart, Allen; Walker, Robert

    2016-01-01

    We introduce the package PhylogeneticTrees for Macaulay2 which allows users to compute phylogenetic invariants for group-based tree models. We provide some background information on phylogenetic algebraic geometry and show how the package PhylogeneticTrees can be used to calculate a generating set for a phylogenetic ideal as well as a lower bound for its dimension. Finally, we show how methods within the package can be used to compute a generating set for the join of any two ideals.

  6. Influence of climate change on the flowering of temperate fruit trees

    Science.gov (United States)

    Perez-Lopez, D.; Ruiz-Ramos, M.; Sánchez-Sánchez, E.; Centeno, A.; Prieto-Egido, I.; Lopez-de-la-Franca, N.

    2012-04-01

    It is well known that winter chilling is necessary for the flowering of temperate trees. The chilling requirement is a criterion for choosing a species or variety at a given location. Also chemistry products can be used for reducing the chilling-hours needs but make our production more expensive. This study first analysed the observed values of chilling hours for some representative agricultural locations in Spain for the last three decades and their projected changes under climate change scenarios. Usually the chilling is measured and calculated as chilling-hours, and different methods have been used to calculate them (e.g. Richarson et al., 1974 among others) according to the species considered. For our objective North Carolina method (Shaltout and Unrath, 1983) was applied for apples, Utah method (Richardson et al. 1974) for peach and grapevine and the approach used by De Melo-Abreu et al. (2004) for olive trees. The influence of climate change in temperate trees was studied by calculating projections of chilling-hours with climate data from Regional Climate Models (RCMs) at high resolution (25 km) from the European Project ENSEMBLES (http://www.ensembles-eu.org/). These projections will allow for analysing the modelled variations of chill-hours between 2nd half of 20C and 1st half of 21C at the study locations.

  7. Using ROC curves to compare neural networks and logistic regression for modeling individual noncatastrophic tree mortality

    Science.gov (United States)

    Susan L. King

    2003-01-01

    The performance of two classifiers, logistic regression and neural networks, are compared for modeling noncatastrophic individual tree mortality for 21 species of trees in West Virginia. The output of the classifier is usually a continuous number between 0 and 1. A threshold is selected between 0 and 1 and all of the trees below the threshold are classified as...

  8. Data acquisition in modeling using neural networks and decision trees

    Directory of Open Access Journals (Sweden)

    R. Sika

    2011-04-01

    Full Text Available The paper presents a comparison of selected models from area of artificial neural networks and decision trees in relation with actualconditions of foundry processes. The work contains short descriptions of used algorithms, their destination and method of data preparation,which is a domain of work of Data Mining systems. First part concerns data acquisition realized in selected iron foundry, indicating problems to solve in aspect of casting process modeling. Second part is a comparison of selected algorithms: a decision tree and artificial neural network, that is CART (Classification And Regression Trees and BP (Backpropagation in MLP (Multilayer Perceptron networks algorithms.Aim of the paper is to show an aspect of selecting data for modeling, cleaning it and reducing, for example due to too strong correlationbetween some of recorded process parameters. Also, it has been shown what results can be obtained using two different approaches:first when modeling using available commercial software, for example Statistica, second when modeling step by step using Excel spreadsheetbasing on the same algorithm, like BP-MLP. Discrepancy of results obtained from these two approaches originates from a priorimade assumptions. Mentioned earlier Statistica universal software package, when used without awareness of relations of technologicalparameters, i.e. without user having experience in foundry and without scheduling ranks of particular parameters basing on acquisition, can not give credible basis to predict the quality of the castings. Also, a decisive influence of data acquisition method has been clearly indicated, the acquisition should be conducted according to repetitive measurement and control procedures. This paper is based on about 250 records of actual data, for one assortment for 6 month period, where only 12 data sets were complete (including two that were used for validation of neural network and useful for creating a model. It is definitely too

  9. Nonparametric Tree-Based Predictive Modeling of Storm Outages on an Electric Distribution Network.

    Science.gov (United States)

    He, Jichao; Wanik, David W; Hartman, Brian M; Anagnostou, Emmanouil N; Astitha, Marina; Frediani, Maria E B

    2017-03-01

    This article compares two nonparametric tree-based models, quantile regression forests (QRF) and Bayesian additive regression trees (BART), for predicting storm outages on an electric distribution network in Connecticut, USA. We evaluated point estimates and prediction intervals of outage predictions for both models using high-resolution weather, infrastructure, and land use data for 89 storm events (including hurricanes, blizzards, and thunderstorms). We found that spatially BART predicted more accurate point estimates than QRF. However, QRF produced better prediction intervals for high spatial resolutions (2-km grid cells and towns), while BART predictions aggregated to coarser resolutions (divisions and service territory) more effectively. We also found that the predictive accuracy was dependent on the season (e.g., tree-leaf condition, storm characteristics), and that the predictions were most accurate for winter storms. Given the merits of each individual model, we suggest that BART and QRF be implemented together to show the complete picture of a storm's potential impact on the electric distribution network, which would allow for a utility to make better decisions about allocating prestorm resources. © 2016 Society for Risk Analysis.

  10. Significance of Bias Correction in Drought Frequency and Scenario Analysis Based on Climate Models

    Science.gov (United States)

    Aryal, Y.; Zhu, J.

    2015-12-01

    Assessment of future drought characteristics is difficult as climate models usually have bias in simulating precipitation frequency and intensity. To overcome this limitation, output from climate models need to be bias corrected based on the specific purpose of applications. In this study, we examine the significance of bias correction in the context of drought frequency and scenario analysis using output from climate models. In particular, we investigate the performance of three widely used bias correction techniques: (1) monthly bias correction (MBC), (2) nested bias correction (NBC), and (3) equidistance quantile mapping (EQM) The effect of bias correction in future scenario of drought frequency is also analyzed. The characteristics of drought are investigated in terms of frequency and severity in nine representative locations in different climatic regions across the United States using regional climate model (RCM) output from the North American Regional Climate Change Assessment Program (NARCCAP). The Standardized Precipitation Index (SPI) is used as the means to compare and forecast drought characteristics at different timescales. Systematic biases in the RCM precipitation output are corrected against the National Centers for Environmental Prediction (NCEP) North American Regional Reanalysis (NARR) data. The results demonstrate that bias correction significantly decreases the RCM errors in reproducing drought frequency derived from the NARR data. Preserving mean and standard deviation is essential for climate models in drought frequency analysis. RCM biases both have regional and timescale dependence. Different timescale of input precipitation in the bias corrections show similar results. Drought frequency obtained from the RCM future (2040-2070) scenarios is compared with that from the historical simulations. The changes in drought characteristics occur in all climatic regions. The relative changes in drought frequency in future scenario in relation to

  11. Risk assessment of complex accident scenarios

    International Nuclear Information System (INIS)

    Kluegel, Jens-Uwe

    2012-01-01

    The use of methods of risk assessment in accidents in nuclear plants is based on an old tradition. The first consistent systematic study is considered to be the Rasmussen Study of the U.S. Nuclear Regulatory Commission, NRC, WASH-1400. Above and beyond the realm of nuclear technology, there is an extensive range of accident, risk and reliability research into technical-administrative systems. In the past, it has been this area of research which has led to the development of concepts of safety precautions of the type also introduced into nuclear technology (barrier concept, defense in depth, single-failure criterion), where they are now taken for granted as trivial concepts. Also for risk analysis, nuclear technology made use of methods (such as event and fault tree analyses) whose origins were outside the nuclear field. One area in which the use of traditional methods of probabilistic safety analysis is encountering practical problems is risk assessment of complex accident scenarios in nuclear technology. A definition is offered of the term 'complex accident scenarios' in nuclear technology. A number of problems are addressed which arise in the use of traditional PSA procedures in risk assessment of complex accident scenarios. Cases of complex accident scenarios are presented to demonstrate methods of risk assessment which allow robust results to be obtained even when traditional techniques of risk analysis are maintained as a matter of principle. These methods are based on the use of conditional risk metrics. (orig.)

  12. Scenario modelling of land use/land cover changes in Munessa-Shashemene landscape of the Ethiopian highlands.

    Science.gov (United States)

    Kindu, Mengistie; Schneider, Thomas; Döllerer, Martin; Teketay, Demel; Knoke, Thomas

    2018-05-01

    Models under a set of scenarios are used to simulate and improve our understanding of land use/land cover (LULC) changes, which is central for sustainable management of a given natural resource. In this study, we simulated and examined the possible future LULC patterns and changes in Munessa-Shashemene landscape of the Ethiopian highlands covering four decades (2012-2050) using a spatially explicit GIS-based model. Both primary and secondary sources were utilized to identify relevant explanatory variables (drivers) and LULC datasets for the model. Three alternative scenarios, namely Business As Usual (BAU), Forest Conservation and Water Protection (FCWP) and Sustainable Intensification (SI) were used. The simulated LULC map of 2012 was compared with the actual for model validation and showed a good consistency. The results revealed that areas of croplands will increase widely under the BAU scenario and would expand to the remaining woodlands, natural forests and grasslands, reflecting vulnerability of these LULC types and potential loss of associated ecosystem service values (ESVs). FCWP scenario would bring competition among other LULC types, particularly more pressure to the grassland ecosystem. Hence, the two scenarios will result in severe LULC dynamics that lead to serious environmental crisis. The SI scenario, with holistic approach, demonstrated that expansion of croplands could vigorously be reduced, remaining forests better conserved and degraded land recovered, resulting in gains of the associated total ESVs. We conclude that a holistic landscape management, i.e. SI, is the best approach to ensure expected production while safeguarding the environment of the studied landscape and elsewhere with similar geographic settings. Further study is suggested to practically test our framework through a research for development approach in a test site so that it can be used as a model area for effective use and conservation of our natural resources. Copyright

  13. Temperature-based modeling of reference evapotranspiration using several artificial intelligence models: application of different modeling scenarios

    Science.gov (United States)

    Sanikhani, Hadi; Kisi, Ozgur; Maroufpoor, Eisa; Yaseen, Zaher Mundher

    2018-02-01

    The establishment of an accurate computational model for predicting reference evapotranspiration (ET0) process is highly essential for several agricultural and hydrological applications, especially for the rural water resource systems, water use allocations, utilization and demand assessments, and the management of irrigation systems. In this research, six artificial intelligence (AI) models were investigated for modeling ET0 using a small number of climatic data generated from the minimum and maximum temperatures of the air and extraterrestrial radiation. The investigated models were multilayer perceptron (MLP), generalized regression neural networks (GRNN), radial basis neural networks (RBNN), integrated adaptive neuro-fuzzy inference systems with grid partitioning and subtractive clustering (ANFIS-GP and ANFIS-SC), and gene expression programming (GEP). The implemented monthly time scale data set was collected at the Antalya and Isparta stations which are located in the Mediterranean Region of Turkey. The Hargreaves-Samani (HS) equation and its calibrated version (CHS) were used to perform a verification analysis of the established AI models. The accuracy of validation was focused on multiple quantitative metrics, including root mean squared error (RMSE), mean absolute error (MAE), correlation coefficient (R 2), coefficient of residual mass (CRM), and Nash-Sutcliffe efficiency coefficient (NS). The results of the conducted models were highly practical and reliable for the investigated case studies. At the Antalya station, the performance of the GEP and GRNN models was better than the other investigated models, while the performance of the RBNN and ANFIS-SC models was best compared to the other models at the Isparta station. Except for the MLP model, all the other investigated models presented a better performance accuracy compared to the HS and CHS empirical models when applied in a cross-station scenario. A cross-station scenario examination implies the

  14. Scenario development methodologies

    International Nuclear Information System (INIS)

    Eng, T.; Hudson, J.; Stephansson, O.

    1994-11-01

    In the period 1981-1994, SKB has studied several methodologies to systematize and visualize all the features, events and processes (FEPs) that can influence a repository for radioactive waste in the future. All the work performed is based on the terminology and basic findings in the joint SKI/SKB work on scenario development presented in the SKB Technical Report 89-35. The methodologies studied are a) Event tree analysis, b) Influence diagrams and c) Rock Engineering Systems (RES) matrices. Each one of the methodologies is explained in this report as well as examples of applications. One chapter is devoted to a comparison between the two most promising methodologies, namely: Influence diagrams and the RES methodology. In conclusion a combination of parts of the Influence diagram and the RES methodology is likely to be a promising approach. 26 refs

  15. SMART-DS: Synthetic Models for Advanced, Realistic Testing: Distribution Systems and Scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Palmintier, Bryan: Hodge, Bri-Mathias

    2017-01-26

    This presentation provides a Smart-DS project overview and status update for the ARPA-e GRID DATA program meeting 2017, including distribution systems, models, and scenarios, as well as opportunities for GRID DATA collaborations.

  16. Modelling land use changes according to transportation scenarios using raster based GIS indicators

    DEFF Research Database (Denmark)

    Fuglsang, Morten; Münier, Bernd; Hansen, Henning Sten

    2012-01-01

    the cellular automata model LUCIA. An Eastern Danish case area was selected, comprising the Copenhagen metropolitan area and its hinterland. The different scenarios are described using a range of different GIS datasets. These include mapping of accessibility based on public and private transportation, urban....... In the EU-FP7 research project PASHMINA (Paradigm Shift modelling and innovative approaches), three storylines of future transportation paradigm shifts towards 2050 are created. These storylines are translated into spatial planning strategies and their implication on land use changes were modelled via...... in urban distribution that different spatial planning strategies may initiate, and thus change the shape of the urban landscape. The scenarios outline different planning strategies, leading to a more homogenous urban structure, targeted at a reduction of transportation work and thus energy consumption...

  17. Modeling and analysis of long-term energy scenarios for sustainable strategies of Ethiopia

    Energy Technology Data Exchange (ETDEWEB)

    Senshaw, Dereje Azemraw

    2014-04-15

    Despite robust economic growth, Ethiopia is one of the countries with poor energy accesses. Contributing factors are poor availability of energy, unreliable and insufficient quality of energy, and insufficient policy. Recognizing that energy access and security are indispensable to economic transformation, Ethiopia needs to cope with key challenges related to energy security, climate change mitigation and also diversification of energy supply. In order to achieve these targets and strive towards sustainable energy for all, Ethiopia's energy system requires a major transformation. The main achievement of this research has been the development of alternative energy options under different conditions for Ethiopia up to 2050. To identify an energy pathway that would meet Ethiopia's energy needs in a sustainable manner, three scenarios are considered: the business-as usual (BAU), moderate shift (Scenario1) and the advanced shift scenario (Scenario 2). The scenarios were developed, quantified and analyzed using a bottom-up model for Long Term Alternative Energy Planning (LEAP). These scenarios represent a range of energy policy measures that Ethiopia could adopt to achieve its sustainable development goals. The BAU scenario reflects a continuation of the current policy trend and considers on economic growth rate of 7%, while Scenario 1 and Scenario 2 represent moderate and advanced levels of commitment in economic growth, energy diversity and reduction of energy import dependency and CO{sub 2} emissions limits, respectively. The scenario analysis shows that the primary energy requirements for Ethiopia's socio-economic development will increase sharply over the period (2010-2050) in all three scenarios. BAU, Scenario 1 and Scenario 2 show an expected to growth at annual rates of 4.1, 4.9 and 5.7% respectively. If the current policy trends (as represented by BAU) continue, the total energy demand in Ethiopia is expected to reach 6,553 Petajoule (PJ) by 2050

  18. Modeling and analysis of long-term energy scenarios for sustainable strategies of Ethiopia

    International Nuclear Information System (INIS)

    Senshaw, Dereje Azemraw

    2014-04-01

    Despite robust economic growth, Ethiopia is one of the countries with poor energy accesses. Contributing factors are poor availability of energy, unreliable and insufficient quality of energy, and insufficient policy. Recognizing that energy access and security are indispensable to economic transformation, Ethiopia needs to cope with key challenges related to energy security, climate change mitigation and also diversification of energy supply. In order to achieve these targets and strive towards sustainable energy for all, Ethiopia's energy system requires a major transformation. The main achievement of this research has been the development of alternative energy options under different conditions for Ethiopia up to 2050. To identify an energy pathway that would meet Ethiopia's energy needs in a sustainable manner, three scenarios are considered: the business-as usual (BAU), moderate shift (Scenario1) and the advanced shift scenario (Scenario 2). The scenarios were developed, quantified and analyzed using a bottom-up model for Long Term Alternative Energy Planning (LEAP). These scenarios represent a range of energy policy measures that Ethiopia could adopt to achieve its sustainable development goals. The BAU scenario reflects a continuation of the current policy trend and considers on economic growth rate of 7%, while Scenario 1 and Scenario 2 represent moderate and advanced levels of commitment in economic growth, energy diversity and reduction of energy import dependency and CO 2 emissions limits, respectively. The scenario analysis shows that the primary energy requirements for Ethiopia's socio-economic development will increase sharply over the period (2010-2050) in all three scenarios. BAU, Scenario 1 and Scenario 2 show an expected to growth at annual rates of 4.1, 4.9 and 5.7% respectively. If the current policy trends (as represented by BAU) continue, the total energy demand in Ethiopia is expected to reach 6,553 Petajoule (PJ) by 2050 from

  19. Benchmarking energy scenarios for China: perspectives from top-down, economic and bottom-up, technical modelling

    DEFF Research Database (Denmark)

    This study uses a soft-linking methodology to harmonise two complex global top-down and bottom-up models with a regional China focus. The baseline follows the GDP and demographic trends of the Shared Socio-economic Pathways (SSP2) scenario, down-scaled for China, while the carbon tax scenario fol......-specific modelling results further. These new sub-regional China features can now be used for a more detailed analysis of China's regional developments in a global context....

  20. Modelling dimensional growth of three street tree species in the ...

    African Journals Online (AJOL)

    The results could also be used in the process of modelling energy use reduction, air pollution uptake, rainfall interception, carbon sequestration and microclimate modification of urban forests such as those found in the City of Tshwane. Keywords: allometry; regression; size relationships; tree growth; urban forests. Southern ...

  1. Using Scenario Visioning and Participatory System Dynamics Modeling to Investigate the Future: Lessons from Minnesota 2050

    Directory of Open Access Journals (Sweden)

    Kathryn J. Draeger

    2010-08-01

    Full Text Available Both scenario visioning and participatory system dynamics modeling emphasize the dynamic and uncontrollable nature of complex socio-ecological systems, and the significance of multiple feedback mechanisms. These two methodologies complement one another, but are rarely used together. We partnered with regional organizations in Minnesota to design a future visioning process that incorporated both scenarios and participatory system dynamics modeling. The three purposes of this exercise were: first, to assist regional leaders in making strategic decisions that would make their communities sustainable; second, to identify research gaps that could impede the ability of regional and state groups to plan for the future; and finally, to introduce more systems thinking into planning and policy-making around environmental issues. We found that scenarios and modeling complemented one another, and that both techniques allowed regional groups to focus on the sustainability of fundamental support systems (energy, food, and water supply. The process introduced some creative tensions between imaginative scenario visioning and quantitative system dynamics modeling, and between creating desired futures (a strong cultural norm and inhabiting the future (a premise of the Minnesota 2050 exercise. We suggest that these tensions can stimulate more agile, strategic thinking about the future.

  2. Spatial soil zinc content distribution from terrain parameters: A GIS-based decision-tree model in Lebanon

    Energy Technology Data Exchange (ETDEWEB)

    Bou Kheir, Rania, E-mail: rania.boukheir@agrsci.d [Lebanese University, Faculty of Letters and Human Sciences, Department of Geography, GIS Research Laboratory, P.O. Box 90-1065, Fanar (Lebanon); Department of Agroecology and Environment, Faculty of Agricultural Sciences (DJF), Aarhus University, Blichers Alle 20, P.O. Box 50, DK-8830 Tjele (Denmark); Greve, Mogens H. [Department of Agroecology and Environment, Faculty of Agricultural Sciences (DJF), Aarhus University, Blichers Alle 20, P.O. Box 50, DK-8830 Tjele (Denmark); Abdallah, Chadi [Natio