Search

Abstract A new high-order statistical moment based on multi-scale (MSHOM) is proposed for researching traditional statistics in this paper. In addition, the indispensable theoretical basis and derivation are illustrated in detail. With the help of three simulated time series, two kinds of situations of MSHOM analysis are mainly discussed in this work. One is accomplished by Gaussian white noise (GWN) and the other is fulfilled with Logistic map and autoregressive fractionally integrated moving-average (ARFIMA). Due to the insufficient performance of MSHOM, we propose an improved MSHOM, which is called MSHOM with control (C-MSHOM). Meanwhile, its performance is tested by the data of US and Chinese stock markets. However, C-MSHOM also brings an extra preprocess stage of data and the uncertainty of selection. To solve these problems, a more generic method, that is, generalized multi-scale high-order moments (G-MSHOM) is given in this paper. Highlights • A new high-order statistical moment is proposed based on multi-scale (MSHOM). • Two improved methods are proposed to widen extent of applications. • The analytic properties of the MSHOM method are presented in detail. • Simulation results show the stability and precision of the MSHOM method. • Benefits of MSHOM and G-MSHOM are shown using US and Chinese stock markets data. [ABSTRACT FROM AUTHOR]

Power split configurations exhibit potential on decreasing fuel consumption. However, how to select the best power split configuration among all the possible configurations still need to be explored. In this paper, a one-dimensional searching ECMS (Equivalent Consumption Minimization Strategy) is developed to evaluate fuel consumption for input power split configuration. Additionally, a battery degradation model based on experimental data is applied to evaluate the battery degradation for input power split configuration. According to one-dimensional searching ECMS and battery degradation model, the impact of different input power split configurations on fuel consumption and battery degradation is investigated. Simulations show that configuration T1 has fuel consumption and battery degradation advantages for PHEV city bus application in China. These advantages are observed because the system efficiency operation points of configuration T1 are closer to the high efficiency area than the system efficiency operation points of other input power split configurations. Furthermore, according to the lever model and one-dimensional searching ECMS method, a power split configuration selection method is provided in this paper. The simulation results based on configuration selection method still indicate that configuration T1 appears to have the best fuel economy for PHEV city bus application. Moreover, configuration T5, with a lever length close to 0, exhibits the worst fuel consumption and battery degradation. [ABSTRACT FROM AUTHOR]

The market for solar energy in the US has grown exponentially due to increased consumer demand resulting from price reduction via economies of scale, technological progress, and a variety of incentives from federal and state governments as well as utility companies. The installation of solar power in Tennessee has more than doubled each year from 2009 to 2011. In this paper, we focus on the behavior of the Tennessee Solar Value Chain (TNSVC) to study the factors that influence growth of solar industry in the state. The impact of existing incentives on the TNSVC is analyzed. The TNSVC is simulated based on inputs from on-site survey to estimate economic impact in terms of the number of jobs added and the tax revenue generated in the state. In addition, a sensitivity analysis for the impact on the TNSVC under different policies those may be adopted by the state of Tennessee in the future is conducted. This paper employs a holistic model which can predict PV installation demand, understand solar value chain capacity, and estimate the revenue generation. It should be noted that the method employed in this study is not unique to the solar energy industry in Tennessee. The data utilized in this study is a combination of public domain information and surveys of suppliers, manufacturers, distributors, and installers. This makes the model in this paper flexible enough to be applied to assess the solar value chain in other state or country. [ABSTRACT FROM AUTHOR]

With increased use of variable refrigerant flow (VRF) systems in the U.S. building sector, interests in capability and rationality of various building energy modeling tools to simulate VRF systems are rising. This paper presents the detailed procedures for model calibration of a VRF system with a dedicated outdoor air system (DOAS) by comparing to detailed measured data from an occupancy emulated small office building. The building energy model is first developed based on as-built drawings, and building and system characteristics available. The whole building energy modeling tool used for the study is U.S. DOE’s EnergyPlus version 8.1. The initial model is, then, calibrated with the hourly measured data from the target building and VRF-DOAS system. In a detailed calibration procedures of the VRF-DOAS, the original EnergyPlus source code is modified to enable the modeling of the specific VRF-DOAS installed in the building. After a proper calibration during cooling and heating seasons, the VRF-DOAS model can reasonably predict the performance of the actual VRF-DOAS system based on the criteria from ASHRAE Guideline 14-2014. The calibration results show that hourly CV-RMSE and NMBE would be 15.7% and 3.8%, respectively, which is deemed to be calibrated. The whole-building energy usage after calibration of the VRF-DOAS model is 1.9% (78.8 kWh) lower than that of the measurements during comparison period. [ABSTRACT FROM AUTHOR]

Abstract: This paper analyzes the welfare effects of slot controls on major US airports. We consider the fundamental tradeoff between benefits from queuing delay reduction and costs due to simultaneous schedule delay increase to passengers while imposing slot limits at airports. A set of quantitative models and simulation procedures are developed to explore the possible airline scheduling responses through reallocating and trimming flights. We find that, of the 35 major US airports, a more widespread use of slot controls would improve travelers’ welfare. The results from our analyses suggest that slot caps at the four airports that currently have slot controls (Washington Reagan, Newark, New York LaGuardia, New York John F. Kennedy) are set too high. Further slot reduction by removing some of the flights at these airports could generate additional benefits to passengers. Slot controls can potentially reduce two thirds of the total system delays caused by congestion. A number of implementation and design issues related to the use of slot controls are also discussed in the paper. [Copyright &y& Elsevier]

Abstract: Set relations are particularly suitable for specifying the small-step operational semantics of synchronous languages. In this paper, a formal library of set relations for the definition, verification of properties, and execution of binary set relations is presented. The formal library consists of a set of theories written in the Prototype Verification System (PVS) that contains definitions and proofs of properties, such as determinism and compositionality, for synchronous relations. The paper also proposes a serialization procedure that enables the simulation of synchronous set relations via set rewriting systems. The library and the serialization procedure are illustrated with the rewriting logic semantics of the Plan Execution Interchange Language (PLEXIL), a rich synchronous plan execution language developed by NASA to support autonomous spacecraft operations. [Copyright &y& Elsevier]

Abstract: Many evolving nuclear energy technologies use advanced predictive multiscale, multiphysics modeling and simulation (M&S) capabilities to reduce the cost and schedule of design and licensing. Historically, the role of experiments has been as a primary tool for the design and understanding of nuclear system behavior, while M&S played the subordinate role of supporting experiments. In the new era of multiscale, multiphysics computational-based technology development, this role has been reversed. The experiments will still be needed, but they will be performed at different scales to calibrate and validate the models leading to predictive simulations for design and licensing. Minimizing the required number of validation experiments produces cost and time savings. The use of multiscale, multiphysics models introduces challenges in validating these predictive tools – traditional methodologies will have to be modified to address these challenges. This paper gives the basic aspects of a methodology that can potentially be used to address these new challenges in the design and licensing of evolving nuclear technology. The main components of the proposed methodology are verification, validation, calibration, and uncertainty quantification – steps similar to the components of the traditional US Nuclear Regulatory Commission (NRC) licensing approach, with the exception of the calibration step. An enhanced calibration concept is introduced here, and is accomplished through data assimilation. The goal of this methodology is to enable best-estimate prediction of system behaviors in both normal and safety-related environments. This goal requires the additional steps of estimating the domain of validation, and quantification of uncertainties, allowing for the extension of results to areas of the validation domain that are not directly tested with experiments. These might include the extension of the M&S capabilities for application to full-scale systems. The new methodology suggests a formalism to quantify an adequate level of validation (predictive maturity) with respect to existing data, so that required new testing can be minimized, saving cost by demonstrating that further testing will not enhance the quality of the predictive tools. The proposed methodology is at a conceptual level. Upon maturity, and if considered favorably by the stakeholders, it could serve as a new framework for the next generation of the best estimate plus uncertainty (BEPU) licensing methodology that the NRC has developed. In order to achieve maturity, the methodology must be communicated to scientific, design, and regulatory stakeholders for discussion and debate. This paper is the first step in establishing that communication. [Copyright &y& Elsevier]

Abstract: To maintain ultra-low particle concentrations, cleanrooms can require several hundred air changes per hour. These ventilation rates make cleanrooms 30–50 times more energy intensive than the average U.S. commercial building. There are an estimated 12millionm2 of cleanroom space in the U.S., consuming over 370PJ of energy each year. This paper explores opportunities to improve the energy efficiency of cleanrooms while maintaining or improving operating conditions. This paper documents the modeling of a 1600m2 cleanroom in upstate New York. The TRNSYS model includes TMY2 weather data; building geometry and material properties; empirical data on occupancy, lighting and process equipment; and sophisticated HVAC systems. The model was validated based on metered steam, chilled water and electricity usage. Under 8% error was achieved in all fields. Four strategies were simulated: a heat recovery system for exhaust air, resulting in an 11.4% energy reduction with a 2.7-year simple payback; solar preheating of desiccant dehumidifier regeneration air (2.4% energy reduction, 11.5-year payback); improved lighting controls (0.3% energy reduction, 1.5-year payback); and demand-controlled filtration (4.4% energy reduction, 3.1-year payback). Implementation of recommended strategies is predicted to save 9TJ, 862tonnes of CO2, and $164k annually. [Copyright &y& Elsevier]

Abstract: This paper reports a design and building process of a net-zero-energy modular house, named ElementHouse, which was entered for the 2007 Solar Decathlon competition that was organized by the U.S. Department of Energy. This paper discusses the development of the ElementHouse from its initial concept to the actual construction, which integrated multi-disciplinary knowledge of architecture, mechanical engineering, and electrical engineering. By employing computer-aided simulation tools, several design approaches were developed to achieve the optimal balance among function, aesthetics, economy, and energy—a challenge in many sustainable building designs. A simplified energy model helped to form the building configuration at the preliminary design stage by showing how energy use is affected by various parameters, leading to optimization studies that provided design guidelines towards an energy-efficient building envelope and opening design. Energy modelling also estimated the annual energy use and electricity generation, as well as the costs associated with long-term operation of the house. The energy demand estimate and its daily power profile helped to design the photovoltaic (PV) system. The modular configuration of the building and its roof structure was then iteratively altered to accommodate the PV panels in such a way as to generate the most power and to facilitate interstate transportation of ElementHouse. With the progress of the design process, detailed energy simulation using EnergyPlus provided more accurate estimates of power use and generation and, coupled with daylighting simulation performed with Radiance, permitted finalizing the building envelope, opening, and electric lighting design. The building envelope embraced the passive and low energy philosophy to minimize the annual heating and cooling load and to optimize natural lighting. By illustrating the whole picture of ElementHouse design, this paper discusses a way of effectively designing and building a comfortable and affordable solar house. [Copyright &y& Elsevier]

Abstract: In Service-Oriented Architecture (SOA), the concepts that services can be discovered and application can be composed via service discovery bring great flexibility to application development [Y. Chen, W.T. Tsai, Distributed Service-Oriented Software Development, Kendall/Hunt, 2008, ]. Microsoft Robotics Studio (MSRS) is a recent initiative in applying SOA to embedded systems and one of its key features is its 3-D simulation tool that allows applications to be simulated before deployment. This paper proposes an ontology-based service-oriented simulation framework with MSRS by adding a set of ontology systems, i.e., service ontology, workflow ontology, entity ontology, and environment ontology. These ontology systems store relevant information useful to compose simulation applications, and items stored also cross reference to each other to facilitate reusability and rapid application composition, This paper then provides a detailed case study on a popular robotic game Sumobot using MSRS to illustrate the key concepts and how they can support rapid simulation development. [1] The contents of this paper were developed under a grant from US Department of Defense and the Fund for the Improvement of Postsecondary Education (FIPSE), US Department of Education. However, these contents do not necessarily represent the policy of the Department of Education, and you should not assume endorsement by the Federal Government. 1 [Copyright &y& Elsevier]

Abstract: This paper presents the results of thermal-hydraulic sensitivity calculation of the “Natural Circulation” test at Unit 6, Kozloduy NPP. The RELAP5/MOD3.2 computer code has been used to simulate the Natural Circulation in a VVER-1000 Nuclear Power Plant (NPP) model. The results are an important part of the validation of the RELAP5/MOD3.2 code. A model of VVER-1000 based on Unit 6 of Kozloduy NPP has been developed for the systems thermal-hydraulics code RELAP5/MOD3.2. This model was developed at the Institute for Nuclear Research and Nuclear Energy – Bulgarian Academy of Sciences (INRNE-BAS), Sofia and was used for simulation of the behavior of the real VVER-1000 NPP during the Natural Circulation test. The data included steady-state and operational transient results. The purpose of the experiment, which was done according to the “Program for investigation of primary side Natural Circulation of coolant on NPP”, was to explicitly establish the response of the plant under primary loop Natural Circulation conditions. The possibility to remove approximately 150MW using the Natural Circulation was also demonstrated during the test. The paper discusses the influence of Pressurizer nodalization on calculation of Pressurizer water level. The comparisons between the RELAP5 results and the test data indicate good general agreement. The report also contains a brief summary of the main NPP systems included in the RELAP5 VVER model and the NC transient sequences. This report was possible through the participation of leading specialists from Kozloduy NPP and with the assistance of Argonne National Laboratory, under the International Nuclear Safety Program (INSP) of the United States Department of Energy. [Copyright &y& Elsevier]

Abstract: Current interest in the shipment of liquefied natural gas (LNG) has renewed the debate about the safety of shipping large volumes of flammable fuels. The size of a spreading pool following a release of LNG from an LNG tank ship has been the subject of numerous papers and studies dating back to the mid-1970s. Several papers have presented idealized views of how the LNG would be released and spread across a quiescent water surface. There is a considerable amount of publicly available material describing these idealized releases, but little discussion of how other flammable fuels would behave if released from similar sized ships. The purpose of this paper is to determine whether the models currently available from the United States Federal Energy Regulatory Commission (FERC) can be used to simulate the release, spreading, vaporization, and pool fire impacts for materials other than LNG, and if so, identify which material-specific parameters are required. The review of the basic equations and principles in FERC''s LNG release, spreading, and burning models did not reveal a critical fault that would prevent their use in evaluating the consequences of other flammable fluid releases. With the correct physical data, the models can be used with the same level of confidence for materials such as LPG and gasoline as they are for LNG. [Copyright &y& Elsevier]

Virtual Reality (VR) can reduce time and costs, and lead to increases in quality, in the development of a product. Given the pressure on car companies to reduce time-to-market and to continually improve quality, the automotive industry has championed the use of VR across a number of applications, including design, manufacturing, and training. This paper describes interviews with 11 engineers and employees of allied disciplines from an automotive manufacturer about their current physical and virtual properties and processes. The results guided a review of research findings and scientific advances from the academic literature, which formed the basis of recommendations for future developments of VR technologies and applications. These include: develop a greater range of virtual contexts; use multi-sensory simulation; address perceived differences between virtual and real cars; improve motion capture capabilities; implement networked 3D technology; and use VR for market research. [ABSTRACT FROM AUTHOR]

Daylight Savings Time (DST) is promoted as a tool to conserve energy. However, ex post reduced form estimates of the effects of DST find no evidence of energy savings and find some evidence of a small increase in energy use. This paper investigates this disconnect using detailed individual time use data to look at the behavioral effects of DST. We study how individuals change their time use in response to the abrupt shift in daylight associated with DST. We leverage two natural experiments to identify the effect of DST on behavior. First, we study periods around the annual shift in daylight induced by moving into and out of DST. Second, we compare activities by time interval before and after the change in DST start dates that occurred in 2007. We find cautious evidence that individuals are shifting potentially energy intensive activities earlier in the day, which is consistent with earlier findings of increased energy usage. [ABSTRACT FROM AUTHOR]

Abstract: This paper studies the revised hours of service regulations for truck drivers in the United States which entered into force in July 2013. It provides a detailed model of the new regulation and presents and a new simulation-based method to assess the impact of the rule change on operational costs and road safety. Unlike previous methodologies, the proposed methodology for assessing the impact of hours of service regulations takes into account that, by optimizing routes and schedules, carriers can minimize the economic impact of stricter regulations. Simulation experiments are conducted indicating that the monetized safety benefit of reducing the daily driving time limits is on the same order of magnitude as the increase in operational costs. [Copyright &y& Elsevier]

Summary: The Soil and Water Assessment Tool (SWAT) and the Hydrologic Simulation Program-Fortran (HSPF) are two river basin simulation models with similar scheme of watershed delineation and functionalities. Both have been selected as modeling tools to support decision and policy making in management of the Illinois River Basin, the United States. This paper reports results calibrating and evaluating SWAT and HSPF model to hydrologic data in the Illinois River Basin, with relative performance of two models in hydrologic simulation and model behaviors under calibration being further compared. In this study, two different calibration approaches, the multi-criteria and the generalized likelihood uncertainty estimation (GLUE) method, were used to quantify uncertainties originated from the use of multi-site discharge observations and the presence of equifinal solutions. It is concluded that both models achieved satisfactory performance after the calibration, and the parameter identification of each model was subject to considerable uncertainties. Furthermore, there exist parameter sets that enable the HSPF model to generate more accurate predictions of the discharges in the main stem of the Illinois River than the SWAT model does, but when the two models were run in un-calibrated mode the distributions of the model fit summary statistics for HSPF observed in the Monte Carlo sampling during GLUE calibration are more varied than those for SWAT with heavier tails on the inferior side and SWAT would have comparable performance to HSPF on average. This finding implies that the accuracy that the HSPF model can achieve in a modeling exercise may have more reliance on the efficacy of the calibration procedure, and the application of SWAT may have some advantage when calibration data are lacking or scarce. [Copyright &y& Elsevier]

This is the second part of a two-part paper that integrates economic and industrial ecology methods to estimate the indirect rebound effect from residential energy efficiency investments. We apply the model developed in part one to simulate the indirect rebound, given an estimate of the direct rebound, using a 2002 environmentally-extended input–output model and the 2004 Consumer Expenditure Survey (in 2002$) for the U.S. We find an indirect rebound of 5–15% in primary energy and CO2e emissions, assuming a 10% direct rebound, depending on the fuel saved with efficiency and household income. The indirect rebound can be as high as 30–40% in NOx or SO2 emissions for efficiency in natural gas services. The substitution effect modeled in part one is small in most cases, and we discuss appropriate applications for proportional or income elasticity spending assumptions. Large indirect rebound effects occur as the U.S. electric grid becomes less-carbon intensive, in households with large transportation demands, or as energy prices increase. Even in extreme cases, there is limited evidence for backfire, or a rebound effect greater than 100%. Enacting pollution taxes or auctioned permits that internalize the externalities of energy use would ensure that rebound effects unambiguously increase consumers'' welfare. [Copyright &y& Elsevier]

Abstract: Biofuel production from renewable biomass has experienced increased interest in order to reduce U.S. dependence on imported oil and reduce carbon emissions. Concerns regarding cost efficiency and environmental problems result in significant challenges that hinder the increased biofuel production from renewable biomass. This paper describes the development of a simulation model with an easy-to-use graphical user interface for the biofuel supply chain. The model considers key supply chain activities including biomass harvesting/processing, transportation, and storage. The model uses the delivered feedstock cost, energy consumption, and GHG emissions as system performance criteria. The utility of the supply chain simulation model is demonstrated by considering a biomass supply chain for a biofuel facility in the lower peninsula of Michigan. The results show that the model is a useful tool for supply chain management, including selection of the optimal biofuel facility location, logistics design, inventory management, and information exchange. [Copyright &y& Elsevier]

Abstract: The paper considers the construction of a confidence band for the trend function of a stationary time series. An explicit formula is derived based on polynomial splines and . The performance of the confidence band is illustrated by simulation studies. The proposed method is applied to the analysis of the annual yields of wheat in the United States. [Copyright &y& Elsevier]

Abstract: This paper presents the results of an investigation on the effect of wind turbulence for the reduction of drag for a speed skater. A speed skater competing in an indoor oval is subjected to turbulent flow conditions. Measurements of flow characteristics in a speed skating oval were made and a simulation of those conditions was developed in the NRC 2m×3m Wind Tunnel. Wind tunnel tests on mannequins of a speed skater with force measurement using an external balance have indicated that the reduction of drag coefficient with Reynolds number was strongly affected by the flow conditions. The effects were not consistent for three different positions of a speed skater. [Copyright &y& Elsevier]

Abstract: The Institute of Medicine (IOM) has pointed out that the existing pandemic mitigation models lack the dynamic decision support capability. In this paper, we present a simulation optimization model to generate dynamic strategies for distribution of limited mitigation resources, such as vaccines and antivirals, over a network of regional outbreaks. The model has the capability to redistribute the resources remaining from previous allocations in response to changes in the pandemic progress. The model strives to minimize the impact of ongoing outbreaks and the expected impact of potential outbreaks, considering measures of morbidity, mortality, and social distancing, translated into the societal and economic costs of lost productivity and medical services. The model is implemented on a simulated H5N1 outbreak involving four counties in the state of Florida, U.S. with over four million inhabitants. The performance of our strategy is compared to that of a myopic distribution strategy. Sensitivity analysis is performed to assess the impact of variability of some critical factors on policy performance. The methodology is intended to support public health policy on effective distribution of limited mitigation resources. [Copyright &y& Elsevier]

Abstract: In the early 2000s, NASA made substantial progress in the development of solar sail propulsion systems for use in robotic science and exploration of the solar system. Two different 20-m solar sail systems were produced. NASA has successfully completed functional vacuum testing in their Glenn Research Center’s Space Power Facility at Plum Brook Station, Ohio. The sails were designed and developed by Alliant Techsystems Space Systems and L’Garde, respectively. The sail systems consist of a central structure with four deployable booms that support each sail. These sail designs are robust enough for deployment in a one-atmosphere, one-gravity environment and are scalable to much larger solar sails – perhaps as large as 150m on a side. Computation modeling and analytical simulations were performed in order to assess the scalability of the technology to the larger sizes that are required to implement the first generation of missions using solar sails. Furthermore, life and space environmental effects testing of sail and component materials was also conducted. NASA terminated funding for solar sails and other advanced space propulsion technologies shortly after these ground demonstrations were completed. In order to capitalize on the $30M investment made in solar sail technology to that point, NASA Marshall Space Flight Center funded the NanoSail-D, a subscale solar sail system designed for possible small spacecraft applications. The NanoSail-D mission flew on board a Falcon-1 rocket, launched August 2, 2008. As a result of the failure of that rocket, the NanoSail-D was never successfully given the opportunity to achieve orbit. The NanoSail-D flight spare was flown in the Fall of 2010. This review paper summarizes NASA’s investment in solar sail technology to date and discusses future opportunities. [Copyright &y& Elsevier]

Abstract: The Monte Carlo (MC) method can be applied to simulate brachytherapy treatment planning. The MCNP5 code gives, together with results, a statistical uncertainty associated with them. However, the latter is not the only existing uncertainty related to the simulation and other uncertainties must be taken into account. A complete analysis of all sources of uncertainty having some influence on results of the simulation of brachytherapy treatment is presented in this paper. This analysis has been based on the recommendations of the American Association for Physicist in Medicine (AAPM) and of the International Standard Organisation (ISO). [Copyright &y& Elsevier]

Abstract: It has been a long history for testing whether the underlying distribution belongs to a particular one or a parametric class of distributions. In this paper, we propose some empirical likelihood ratio tests via estimating equations. The proposed new tests allow one to add more relevant constraints so as to improve the powers. A simulation study shows the effectiveness of the new tests. The new method is then used to test employer size and market value distributions of US firms. [Copyright &y& Elsevier]

Abstract: This paper presents the development of a method to optimize a solar-assisted cooling system with limited budget constraints. Regression analysis is used to identify the relationship between the solar fraction and the system factors according to the data provided by experiments. In order to obtain an accurate model to estimate the problem using small number of experimental trials, the method of central composite design (CCD) from design of experiment (DE) is used as a key technique. The experimental trials are conducted in the transient energy system simulation (TRNSYS) tool. Finally, the optimization problem is formulated and solved by including the model as the objective function, the physical constraints of the system factors, and the budget limit. A case study was conducted to apply this optimization method to the design of a solar-assisted double-effect absorption cooling system installed in a small-sized office building in West Lafayette, IN, USA. The results show the developed optimal model strongly agrees with the physical system model in TRNSYS. This optimization method can be generally applied to different types of solar cooling systems, and other renewable energy systems. [Copyright &y& Elsevier]

Abstract: Appropriate benchmarks for water productivity (WP), defined here as the amount of grain yield produced per unit of water supply, are needed to help identify and diagnose inefficiencies in crop production and water management in irrigated systems. Such analysis is lacking for maize in the Western U.S. Corn Belt where irrigated production represents 58% of total maize output. The objective of this paper was to quantify WP and identify opportunities to increase it in irrigated maize systems of central Nebraska. In the present study, a benchmark for maize WP was (i) developed from relationships between simulated yield and seasonal water supply (stored soil water and sowing-to-maturity rainfall plus irrigation) documented in a previous study; (ii) validated against actual data from crops grown with good management over a wide range of environments and water supply regimes (n =123); and (iii) used to evaluate WP of farmer''s fields in central Nebraska using a 3-y database (2005–2007) that included field-specific values for yield and applied irrigation (n =777). The database was also used to quantify applied irrigation, irrigation water-use efficiency (IWUE; amount of yield produced per unit of applied irrigation), and the impact of agronomic practices on both parameters. Opportunities to improve irrigation management were evaluated using a maize simulation model in combination with actual weather records and detailed data on soil properties and crop management collected from a subset of fields (n =123). The linear function derived from the relationship between simulated grain yield and seasonal water supply, namely the mean WP function (slope=19.3kgha−1 mm−1; x-intercept=100mm), proved to be a robust benchmark for maize WP when compared with actual yield and water supply data. Average farmer''s WP in central Nebraska was ∼73% of the WP derived from the slope of the mean WP function. A substantial number of fields (55% of total) had water supply in excess of that required to achieve yield potential (900mm). Pivot irrigation (instead of surface irrigation) and conservation tillage in fields under soybean–maize rotation had the greatest IWUE and yield. Applied irrigation was 41 and 20% less under pivot and conservation tillage than under surface irrigation and conventional tillage, respectively. Simulation analysis showed that up to 32% of the annual water volume allocated to irrigated maize in the region could be saved with little yield penalty, by switching current surface systems to pivot, improving irrigation schedules to be more synchronous with crop water requirements and, as a fine-tune option, adopting limited irrigation. [Copyright &y& Elsevier]

Abstract: Training and process analysis in the construction industry has not taken full advantage of new technologies in simulation, modeling, and semantic web and software engineering. The purpose of this research is to develop a framework for a virtual interactive construction education system taking full advantage of these technologies. The modules will simulate the construction process for a facility from start to finish using information drawn from domain experts using real projects in the built environment. These modules can be used as training tools for new employees where they attempt to optimize time and cost in a virtual environment given a limited number of equipment, time and employee options. They can also be used as a process analysis tool before, during and after construction where a number of situational variables could be analyzed for exposure of potential risk. These modules would be particularly useful for repetitive construction where the initial project or task is analyzed for optimization and risk mitigation. This paper describes the framework using a residential construction example that is a 900 square foot (about 85m2) wood frame single family house designed for the United States. [ABSTRACT FROM AUTHOR]

Abstract: The Advanced Life Support/NASA Specialized Center of Research and Training (ALS/NSCORT) focuses on research and development of technologies to support human habitation during space missions. This research was done as part of an effort to maintain crewmembers’ water supply in a closed life-support system. The water subsystem was the primary focus of this study because water is one of the most expensive and important resources for human survival. This paper focuses on the application of previously-developed methodologies for controlling a water-treatment system. The water-treatment and usage model was set up based on the Baseline Value and Assumptions Document (BVAD) published by NASA. The conditions, or “states”, of the system are captured hourly in the model. Control policies are defined in terms of treatment efficiencies. One control policy is to be used for the system at the beginning of each hour. A simulation is developed to study the impact of different control policies to this model. The Markov Decision Process (MDP) is used to aid the decision of choosing a policy to be used. In order for the MDP to pick the best policy, a state-space exploration technique, the Controlled Random Walk, is used for state-space exploration. This technique, together with re-initialization of initial system conditions, allow the system to visit a larger portion of the state space compared to some other techniques. In order to describe the state transitions, transition-probability matrices need to be computed. A probability-convergence technique is developed to minimize bias while computing these matrices. This technique is based on the Kullback–Leibler divergence measure, but modified for this application. A test case is constructed to assess the performance of best policies. Three scenarios with different levels of fluctuation, or disturbances, of water-consumption and treatment efficiencies are introduced in the test case. Results show that the best policies outperformed cases where fixed policies, as well as random policies, are used in all three scenarios. [Copyright &y& Elsevier]

Abstract: This paper compares spatial and seasonal variations and temporal trends in modeled and measured concentrations of sulfur and nitrogen compounds in wet and dry deposition over an 18-year period (1988–2005) over a portion of the northeastern United States. Substantial emissions reduction programs occurred over this time period, including Title IV of the Clean Air Act Amendments of 1990 which primarily resulted in large decreases in sulfur dioxide (SO2) emissions by 1995, and nitrogen oxide (NOx) trading programs which resulted in large decreases in warm season NOx emissions by 2004. Additionally, NOx emissions from mobile sources declined more gradually over this period. The results presented here illustrate the use of both operational and dynamic model evaluation and suggest that the modeling system largely captures the seasonal and long-term changes in sulfur compounds. The modeling system generally captures the long-term trends in nitrogen compounds, but does not reproduce the average seasonal variation or spatial patterns in nitrate. [ABSTRACT FROM AUTHOR]

Abstract: This paper examines the impact of tripled anthropogenic emissions from China and India over the base level (gaseous species and carbonaceous aerosols for 2000) on air quality over the U.S. using the WRF/Chem (Weather Research and Forecasting – Chemistry) model at 1° resolution. WRF/Chem is a state-of-the-science, fully coupled chemistry and meteorology system suitable for simulating the transport and dispersion of pollutants and their impacts. The analyses in this work were focused on MAM (March, April and May). The simulations indicate an extensive area of elevated pollutant concentrations spanning from the Arabian Sea to the Northern Pacific and to the Northern Atlantic. MAM mean contributions from the tripled Asian emissions over the U.S. are found to be: 6–12 ppbv for CO, 1.0–2.5 ppbv for O3, and 0.6–1.6 μg m−3 for PM2.5 on a daily basis. [Copyright &y& Elsevier]

Many nearshore restoration projects are currently underway at coastal locations where human influence and development have disrupted natural habitat and coastal ecological systems. The objectives of these projects in general are to restore the lost estuarine functions to the tidal marshland. Often these projects are conducted with little understanding of the potential effects of other nearby projects within the ecosystem, and similarly, it is easy to neglect the effect of the local project on the larger estuarine scale. In this paper, a modeling study is presented to evaluate the hydrodynamic responses of multiple restoration projects and their cumulative effect in the Snohomish River estuary in Washington, USA. The concept of absolute mean tidal transport is introduced and used to measure the cumulative effect of the proposed restoration projects on the estuarine hydrodynamics. The results show that the hydrodynamic responses due to multiple restoration projects are additive in the estuary, and the effect is nonlinear. The hydrodynamic response under restoration conditions depends on the size of the restoration area and the geometric configuration of the existing river channels. Within a complex braided estuary such as the Snohomish, the influence of a specific restoration project is not only experienced locally, but also found to significantly affect tidal transport in all distributary branches within the system. [Copyright &y& Elsevier]

Abstract: As of November 2008, the number of cell phone subscribers in the US exceeded 267 million, nearly three times more than the 97 million subscribers in June 2000. This rapid growth in cell phone use has led to concerns regarding their impact on driver performance and road safety. Numerous legislative efforts are under way to restrict hand-held cell phone use while driving. Since 1999, every state has considered such legislation, but few have passed primary enforcement laws. As of 2008, six states, the District of Columbia (DC), and the Virgin Islands have laws banning the use of hand-held cell phones while driving. A review of the literature suggests that in laboratory settings, hand-held cell phone use impairs driver performance by increasing tension, delaying reaction time, and decreasing awareness. However, there exists insufficient evidence to prove that hand-held cell phone use increases automobile-accident-risk. In contrast to other research in this area that uses questionnaires, tests, and simulators, this study analyzes the impact of hand-held cell phone use on driving safety based on historical automobile-accident-risk-related data and statistics, which would be of interest to transportation policy-makers. To this end, a pre-law and post-law comparison of automobile accident rate measures provides one way to assess the effect of hand-held cell phone bans on driving safety; this paper provides such an analysis using public domain data sources. A discussion of what additional data are required to build convincing arguments in support of or against legislation is also provided. [Copyright &y& Elsevier]

Abstract: Active debris removal (ADR) was suggested as a potential means to remediate the low Earth orbit (LEO) debris environment as early as the 1980s. The reasons ADR has not become practical are due to its technical difficulties and the high cost associated with the approach. However, as the LEO debris populations continue to increase, ADR may be the only option to preserve the near-Earth environment for future generations. An initial study was completed in 2007 to demonstrate that a simple ADR target selection criterion could be developed to reduce the future debris population growth. The present paper summarizes a comprehensive study based on more realistic simulation scenarios, including fragments generated from the 2007 Fengyun-1C event, mitigation measures, and other target selection options. The simulations were based on the NASA long-term orbital debris projection model, LEGEND. A scenario where, at the end of mission lifetimes, spacecraft and upper stages were moved to 25-year decay orbits, was adopted as the baseline environment for comparison. Different annual removal rates and different ADR target selection criteria were tested, and the resulting 200-year future environment projections were compared with the baseline scenario. Results of this parametric study indicate that (1) an effective removal strategy can be developed using a selection criterion based on the mass and collision probability of each object, and (2) the LEO environment can be stabilized in the next 200 years with an ADR removal rate of five objects per year. [Copyright &y& Elsevier]

Abstract: Hydrocephalus, a condition which affects thousands of people annually in the US alone, arises as a result of a build-up of cerebrospinal fluid (CSF) in the brain’s ventricular cavity due to an imbalance between the rates of CSF production and absorption. Although the earliest known instances of hydrocephalus date back to the time of Hippocrates, the pathophysiology of hydrocephalus is still poorly understood, and is the subject of active debate in the literature. Recently, the pulsations of the cerebrospinal fluid have been suggested as a possible mechanism for ventricular expansion. In this paper, we attempt to determine the significance of these pulsations in the development of hydrocephalus by simulating their mechanical effects on the brain. The brain parenchyma is modelled as a fractional Zener viscoelastic solid, which extends the work previously presented in Sivaloganathan et al. [S. Sivaloganathan, M. Stastna, G. Tenti, J. Drake, A viscoelastic model of the brain parenchyma with pulsatile ventricular pressure, Appl. Math. Comput. 165 (2005) 687–698]. Explicit solutions for the displacement and stresses are obtained by solving the boundary value problems corresponding to the cases of infant and adult hydrocephalus. As expected, when the cranial vault is a rigid container, as in adult hydrocephalus, very small displacements are predicted. [Copyright &y& Elsevier]

Abstract: X-ray phase contrast imaging solves the basic problem of conventional X-ray imaging, i.e. low image contrast arising from small absorption differences. For years X-ray phase contrast imaging was thought to be restricted to synchrotron radiation facilities, but a new approach was recently developed at UCL which makes synchrotron-like phase effects achievable with conventional sources, by introducing two separate sets of appropriately designed coded-apertures at either side of the imaged object. Although most proposed applications of X-ray phase contrast imaging are focused on medical aspects, substantial advantages can be gained in other fields, including security inspections. In this case the system has to be based around higher X-ray energies, which has an impact on the system design. This paper describes such a design. A previously developed and experimentally validated simulation program was used to estimate the image contrast that can be expected from a range of details of interest in security inspections imaged under various conditions, including beam spectrum, detector characteristics, coded-aperture design, source-to-sample and sample-to-detector distances, etc.—while taking into account the interplay between these different parameters. The conditions providing maximum image contrast were chosen and used in the ultimate system design. [Copyright &y& Elsevier]

Summary: The main aim of frequency analysis of hydrological data is the definition of the quantiles with a given return period, also known as return levels, namely, the values of a hydrological variable X exceeded on average once in T time intervals. To make the analysis effective, these values have to be complemented with information about their uncertainty, which is usually quantified by confidence intervals (CIs). The paper discusses and compares some parametric, non-parametric, and simulation techniques to build CIs for quantiles with emphasis on the extreme ones. In particular, the work focuses on the usefulness of fractional order statistics to compute CIs for quantiles. This approach appears attractive as it involves simple analytical formulas and allows computing fully non-parametric CIs without requiring information about the parent distribution of the data. Since CIs for order statistics can be used to approximate CIs for quantiles based on order statistics, the relation between them is explored as well. The applicability of methods based on order statistics is assessed by studying the actual coverage probability through simulations, and applying these approaches to annual maximum peak discharge records from 22 streamgage stations in the continental United States and a streamgage station downtown Rome, Italy. For extreme quantiles, results show that these techniques are generally outperformed in term of coverage probability by other methods, such as Monte Carlo approach, when the parent distribution is well-specified or mis-specification involves distributions with tail behavior similar to the one used to generate the sample. On the other hand, the application to real world data indicates that the values of confidence limits based on order statistics are close to those obtained by Monte Carlo approach. In particular, the upper limits from non-parametric setups often result in cautionary values. [Copyright &y& Elsevier]

Abstract: The great Lisbon earthquake of November 1st, 1755 with an estimated moment magnitude of 8.5–9.0 was the most destructive earthquake in European history. The associated tsunami run-up was reported to have reached 5–15 m along the Portuguese and Moroccan coasts and the run-up was significant at the Azores and Madeira Island. Run-up reports from a trans-oceanic tsunami were documented in the Caribbean, Brazil and Newfoundland (Canada). No reports were documented along the U.S. East Coast. Many attempts have been made to characterize the 1755 Lisbon earthquake source using geophysical surveys and modeling the near-field earthquake intensity and tsunami effects. Studying far field effects, as presented in this paper, is advantageous in establishing constraints on source location and strike orientation because trans-oceanic tsunamis are less influenced by near source bathymetry and are unaffected by triggered submarine landslides at the source. Source location, fault orientation and bathymetry are the main elements governing transatlantic tsunami propagation to sites along the U.S. East Coast, much more than distance from the source and continental shelf width. Results of our far and near-field tsunami simulations based on relative amplitude comparison limit the earthquake source area to a region located south of the Gorringe Bank in the center of the Horseshoe Plain. This is in contrast with previously suggested sources such as Marqués de Pombal Fault, and Gulf of Cádiz Fault, which are farther east of the Horseshoe Plain. The earthquake was likely to be a thrust event on a fault striking ~345° and dipping to the ENE as opposed to the suggested earthquake source of the Gorringe Bank Fault, which trends NE–SW. Gorringe Bank, the Madeira-Tore Rise (MTR), and the Azores appear to have acted as topographic scatterers for tsunami energy, shielding most of the U.S. East Coast from the 1755 Lisbon tsunami. Additional simulations to assess tsunami hazard to the U.S. East Coast from possible future earthquakes along the Azores–Iberia plate boundary indicate that sources west of the MTR and in the Gulf of Cadiz may affect the southeastern coast of the U.S. The Azores–Iberia plate boundary west of the MTR is characterized by strike–slip faults, not thrusts, but the Gulf of Cadiz may have thrust faults. Southern Florida seems to be at risk from sources located east of MTR and South of the Gorringe Bank, but it is mostly shielded by the Bahamas. Higher resolution near-shore bathymetry along the U.S. East Coast and the Caribbean as well as a detailed study of potential tsunami sources in the central west part of the Horseshoe Plain are necessary to verify our simulation results. [Copyright &y& Elsevier]

Abstract: Recently, several improvements were made in the DORIS data processing at the IGN/JPL (Institut Geographique National, France; Jet Propulsion Laboratory, California Institute of Technology, USA) analysis center: use of GRACE-derived gravity fields, data preprocessing and station discontinuity detection, etc. This allowed enhanced performances for ground station geodetic positioning (typically 10mm using a week of data), as well as for polar motion (0.5–1.0 mass for daily determination). However, since the loss in 2004 of the DORIS receiver on the TOPEX/Poseidon mission, only four satellites (SPOT-2, SPOT-4, SPOT-5, and ENVISAT) are currently equipped with DORIS receivers. Furthermore, most of them are aging and some have already far exceeded their expected lifetime. The goal of this paper is to analyze how the geodetic performances could be degraded in the future if one or more of these satellites would unfortunately be lost, and to envisage which satellites are currently the most critical in the DORIS geodetic performances. We have reanalyzed 1 year of recent DORIS data (2005), processing all possible combinations of satellite constellation sub-sets. We then compared these results (station coordinates and polar motion) with those obtained in regular data processing when using DORIS data from all four available satellites in 2005. We demonstrate the importance of the SPOT-5 data, equipped with a new type of on-board DORIS receiver. The study also shows some possible weaknesses in our current ENVISAT orbit computations. Fortunately, new DORIS satellites are also expected in the near future (Jason-2, CRYOSAT-2 and AltiKa), which could improve current DORIS-derived geodetic results due to their specific type of orbit (different from the SPOT sun-synchronous orbits) and also to enhanced on-board receivers. [Copyright &y& Elsevier]

SAFE_AIR II is a model which simulates transport and diffusion of airborne pollutants emitted in the low atmosphere above complex orography at both local and regional scale, under non-stationary and inhomogeneous emission and meteorological conditions. The aim of this paper is the assessment of the performance of the dispersive module (P6) of SAFE_AIR II in simulating pollutant concentrations due to releases from area sources. This analysis has been carried out comparing the results of model simulations with the data collected in a U.S. Environmental Protection Agency Meteorological Wind Tunnel. Three different scenarios have been investigated in order to understand the effects of the shape and orientation of the area source. To compare measured concentrations against the corresponding predicted ones, both graphical analyses and appropriate statistical indices have been used. The capability of the code to simulate area sources has been outlined. [Copyright &y& Elsevier]

This paper details modeling assumptions and simulation results for an unglazed collector system supplying domestic hot water, space heating, and space cooling loads. Collectors are modeled using unglazed collector test results. Variation of savings with collector area, storage volume, heat exchanger size, and wind for the Albuquerque, NM climate are shown. Over the storage-to-collector ratio range of 40–640 l/m2 collector, annual savings varies only ±15%. Cooling is sensitive to heat exchanger size, and heating is sensitive to wind velocity. At a collector area of 23 m2, the unglazed system meets about 56% of the annual total energy demand, saving 25.9 $/m2 yr for an all-electric home. For the 23 m2 area, savings for a cold/damp (Madison) and a hot/humid (Miami) climate are 64% and 56%, respectively, of the savings in Albuquerque. [Copyright &y& Elsevier]

We describe and validate a simple PV simulation model capable of predicting average PV output as a function of array geometry (slope and azimuth) and location. This simulation tool is used in the Clean Power Estimator––a web-based PV economic evaluation program available in the US and several countries. Results show that the simplified model accurately captures array geometry, seasonal and daily PV output variations when benchmarked against a standard PV simulation program. This paper concludes that web-based Clean Power Estimator simulations have a sound physical basis. [Copyright &y& Elsevier]