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Background Study: Technology‐supported learning environments, act as significant observational and enabling indicators for evaluating and encouraging the digital revolution of education, are of vital importance in current educational research. Keeping track of the dynamics of technology‐supported learning environment research allows for the enrichment of theoretical studies and a prompt innovation of talent‐training environments. Objectives: The present study carried out a bibliometric analysis of the core collection of WoS database over the last two decades. Method: This study is a bibliometric research. We applied CiteSpace and VOSviewer for co‐occurrence and evolution analysis. In addition, we extracted the fundamental ideas and thoughts through reading and analysis. Results: First, the study found that technology‐supported learning environment research is in a growth phase, with core journals such as Interactive Learning Environments or Computers & Education. The findings show that a core research team comprised of such scholars as Hwang Gwo‐Jen, Lester James C. and Wong Lung‐Hsiang. Key nations of publishing and research strength are from China, the United States, the United Kingdom and the Netherlands. Second, the hot topics in research on technology‐supported learning environments were virtual learning environments, technology‐enabled learning environments and interactive learning environments. Nine study specifics were derived from these three topics such as moulding function, generating scenario, stimulating sensation, effect verification, design idea, research reflection, inquiry and research, virtual community, and mixed environment. Lastly, the frontier evolution offers a pattern of development from enhancing performance to changing mode to incorporating experience. Conclusion: Looking ahead, our research recommendations for the field of technology‐supported learning environments include a multifaceted approach. We should aim to enhance research designs and methodologies, develop contemporary guiding theories and strive for a balanced representation across various educational domains, expanding our scope to encompass all academic disciplines. In terms of practical application, it is imperative to focus on the design and implementation of technology‐supported learning environments from three critical perspectives: "change‐demand," "student‐learning" and "online‐offline." These approaches will collectively ensure that technology‐supported learning environments are both innovative and responsive to the diverse needs of the educational landscape. Lay Description: What is already known about this topic: Technology‐supported learning environments are currently a focal and hot research topic in the field of education.Although numerous studies have been conducted on the learning environment of technical support, there has yet to be a systematic and comprehensive review of the related research. What this paper adds: This study provides a comprehensive review of research on the technology‐supported learning environments over the past two decades.This study primarily presents an overview of research on the technology‐supported learning environments over the past two decades, focusing on main literature, research strength, hot topics and frontier evolution. Implications for practice and/or policy: Researchers need to further advance research on technology‐supported learning environments by enriching research designs and methods, constructing up‐to‐date guiding theories and achieving a balance across different educational domains while extending the reach to all disciplines.Educational practitioners need to pay attention to the design and implementation of technology‐supported learning environments from the three viewpoints of "change‐demand," "student‐learning" and "online‐offline." [ABSTRACT FROM AUTHOR]

This case study demonstrates the application of an unsupervised topic modeling algorithm to 7,773 English-language articles published in the Library Quarterly from 1931 to 2015. The analysis of 85 years of the journal's output follows an exploratory data analysis framework to generate novel hypotheses about the history of LIS using topic modeling, a method for identifying clusters of co-occurring words within large collections of text. The paper closely examines two topics that suggest differences in gender representation in the journal to propose and support a new hypothesis regarding the historical inclusion of gendered objects of study in LIS literature. [ABSTRACT FROM AUTHOR]

Highlights • 3D models can be used to accurately predict flood wave propagation in natural environments. • 3D non-hydrostatic models can be used to study cases when flow becomes locally pressurized. • 3D models can be used to estimate effectiveness of flood protection measures. Abstract This paper discusses development and validation of a 3-D, non-hydrostatic, Reynolds-Averaged Navier–Stokes (RANS) model using the Volume of Fluid (VOF) approach to simulate flooding events in natural environments. A series of validation simulations in simple and complex geometries are performed to test the different modules of the flow solver. The paper also discusses the differences between simulation results obtained using the 3-D model and those obtained using a standard, 2-D hydrostatic, depth-averaged model. The predictions by the two models show fairly large differences in regions where 3-D effects are expected to be significant (e.g., in regions containing highly-curved river reaches and near hydraulic structures). Then, the validated 3-D model is employed to investigate the efficiency of using flood-protection walls to reduce adverse effects of flooding in the Iowa River near Iowa City, Iowa, USA. Finally, the propagation of a flood wave in a reach of the Iowa River containing a bridge is simulated and the effects of the flow becoming pressurized beneath the bridge deck are discussed. For such applications, in which the regime can change locally between open channel and pressurized flow, the use of fully 3-D, non-hydrostatic models may be the only viable option to accurately predict flow hydrodynamics and its effects on bed shear stresses and sediment entrainment potential, especially around locations where the flow becomes pressurized. [ABSTRACT FROM AUTHOR]

• We evaluate the empirical relevance of the profit-squeeze mechanism to HP and Hamilton filters using quarterly data for the United States from 1948-67 to 2016. • We extend Goodwin's (1967) growth-cycle model to include the employment rate, income distribution, and capacity utilisation as endogenous variables. • We show analytically that the system always admits a family of periodic solutions. • The model is estimated econometrically using the Autoregressive Distributed Lag (ARDL) approach. • Through numerical simulations and making use of our estimations, we confirm that fluctuations are persistent and bounded. Vector Autoregressive (VAR) models have been applied for a long time now to study profit-squeeze cycles, most of the time using problematic Hodrick-Prescott (HP) filtered time series. In a recent paper, Hamilton (2018) has provided a simple alternative that overcomes the main drawbacks of the HP procedure. In order to evaluate the empirical relevance of the profit-squeeze mechanism, we compare both methodologies using quarterly data for the United States after the Second World War. It is shown that using the Hamilton detrending method significantly increases the magnitude as well as the time length of the response. Furthermore, we present an extension of Goodwin's (1967) growth-cycle model that includes employment rates, income distribution, and capacity utilisation as endogenous variables. We demonstrate analytically that the system always admits a family of periodic solutions. The model is estimated using the Autoregressive Distributed Lag (ARDL) approach. Through numerical simulations and making use of our estimations, we confirm that fluctuations are persistent and bounded. [ABSTRACT FROM AUTHOR]

This paper develops a frequentist model averaging approach for threshold model specifications. The resulting estimator is proved to be asymptotically optimal in the sense of achieving the lowest possible squared errors. In particular, when combining estimators from threshold autoregressive models, this approach is also proved to be asymptotically optimal. Simulation results show that for the situation where the existing model averaging approach is not applicable, our proposed model averaging approach has a good performance; for the other situations, our proposed model averaging approach performs marginally better than other commonly used model selection and model averaging methods. An empirical application of our approach on the US unemployment data is given. [ABSTRACT FROM AUTHOR]

Abstract For future engines to become more efficient, with enhanced fuel economy and increased power output, accurate prediction of new designs is required over the full lifetime of an engine. The analysis uses of a local pressure coefficient of boundary shear strength of asperities value, taking into account the localised effects of surface texture, coating and surface deposition. XPS spectra analysis was also carried out to identify the surface depositions as a result of combustion, not previously taken into account during piston ring pack simulation. It was found that piston varnish on the liner corresponded to higher values of the pressure coefficient of boundary shear strength of asperities, showing the importance of using real system components run under representative operating conditions. Highlights • The paper presents measurements of ς from a used real cylinder liner surface. • XPS is used to identify chemical composition of liner surface regions. • Depositions and tribo-films on the liner surface are characterised. • Results show that boundary friction is dependent on the by-products of combustion over time. • Simulation shows that results for friction can vary by 30% at peak combustion pressure. [ABSTRACT FROM AUTHOR]

This paper describes environmental systems games developed for energy and water resource use designed to be adaptable from high school to undergraduate use. Two of the games are computer simulations with adjustable levels of difficulty that can be done in a computer lab or as a homework assignment. The third is a peer-to-peer roleplayer game designed for an immersive in-class simulation. For the energy and the peer-to-peer water games, we describe (1) the overall strategy or story line adopted, (2) the manner in which the game is played by students in a classroom setting, (3) the use of scientific literature in conceptualizing and parameterizing the game, and (4) possible game extensions. Preliminary data from use at the undergraduate level shows that the games are very well-received by students and, consistent with other research on quasi-experimental simulations, likely enhance learning outcomes. [ABSTRACT FROM AUTHOR]

To address the inadequacy of ambulance design standards, the Department of Homeland Security Science and Technology Directorate, the National Institute of Standards and Technology, the National Institute for Occupational Safety and Health, and BMT Designers and Planners have collaborated to develop new design standards for ambulance patient compartments. This paper presents a simulation-based approach to evaluate and guide improving patient compartment designs that conform to developed requirements for better performance and safety of ambulance users. Those requirements address hazards stemming from (1) the inability of providers to remain safely restrained while treating patients, and (2) the musculoskeletal damage from awkward body postures. An initial design was developed through the axiomatic design approach with inputs from stakeholders such as emergency medical service providers and ambulance manufacturers. The design was imported into a human task simulation tool. It was tested for performance to identify areas for further improvements, which resulted in a second design concept. This paper shows how computer simulation was used to evaluate the effectiveness of the two successive design concepts in enabling providers to perform a range of medical care tasks while remaining seated and restrained. We also evaluated the musculoskeletal effect of these designs on the providers. The results showed that using a simulation-based evaluation produced patient compartments that better meet user requirements when compared with traditional designs. This research produced a set of requirements and recommendations that we believe will lead to better design standards and guidelines for the next generation of ambulances. [ABSTRACT FROM AUTHOR]

The American automobile industry is facing substantial environmental and energy challenges driving the pursuit of alternative powertrain technologies—“The intervening mechanism by which power is transmitted from an engine to a propeller or axle that it drives,” which nominally includes engine, transmission, drive shafts, differentials, and the final drive. Emerging alternative fuel vehicles are showing their potential to address these challenges. However, diffusion of new technologies has many complications. This paper uses system dynamics modeling to investigate the impacts of individual and organizational parameters. This model embeds two traditional modeling methods for technology adoption, the Bass diffusion model and multinomial logit regression method. Five types of powertrain systems and three major stakeholders are considered. Mathematical relationships among different variables are elaborated. The qualitative impacts of government feebate, manufacturer willingness, and consumer purchasing preferences on economic and environmental issues are addressed using scenario analysis. [ABSTRACT FROM AUTHOR]

Drug-drug interactions (DDIs) are a common cause of adverse drug events (ADEs). The electronic medical record (EMR) database and the FDA's adverse event reporting system (FAERS) database are the major data sources for mining and testing the ADE associated DDI signals. Most DDI data mining methods focus on pair-wise drug interactions, and methods to detect high-dimensional DDIs in medical databases are lacking. In this paper, we propose 2 novel mixture drug-count response models for detecting high-dimensional drug combinations that induce myopathy. The "count" indicates the number of drugs in a combination. One model is called fixed probability mixture drug-count response model with a maximum risk threshold (FMDRM-MRT). The other model is called count-dependent probability mixture drug-count response model with a maximum risk threshold (CMDRM-MRT), in which the mixture probability is count dependent. Compared with the previous mixture drug-count response model (MDRM) developed by our group, these 2 new models show a better likelihood in detecting high-dimensional drug combinatory effects on myopathy. CMDRM-MRT identified and validated (54; 374; 637; 442; 131) 2-way to 6-way drug interactions, respectively, which induce myopathy in both EMR and FAERS databases. We further demonstrate FAERS data capture much higher maximum myopathy risk than EMR data do. The consistency of 2 mixture models' parameters and local false discovery rate estimates are evaluated through statistical simulation studies. [ABSTRACT FROM AUTHOR]

Historically, two-lane highways served primarily as uninterrupted flow connectors between major population centers. Increasingly, however, population growth in areas between the major population centers along these highways is reaching levels such that occasional signalized intersections are commonly present. Given increasing congestion along these routes, particularly as a result of increased signalization, transportation engineers need methods and tools to analyze highway performance. The current analysis methodology contained in the commonly used highway capacity manual (HCM) for two-lane highways is limited in scope to completely uninterrupted-flow facilities. Furthermore, the spacing of signalized intersections along a two-lane highway is typically great enough such that the urban streets analysis methodology of the HCM is not applicable. Until recently, a simulation tool did not exist that could model the combination of two-lane highway segments and signalized intersections. This capability is now incorporated in the corridor simulation (CORSIM) microscopic traffic simulation program. This study uses the updated version of CORSIM to develop an analytical methodology for two-lane highway facilities (i.e., the combination of two-lane highway segments and signalized intersections). This study is a follow-up to a similar one conducted in 2009 at the University of Florida. However, a major distinction is that the previous study had to use a hybrid simulation approach [TWO-lane PASsing and CORridor SIMulation (TWOPAS and CORSIM)] whereas this study used the improved version of CORSIM that provides a unified and more accurate simulation approach. Although many similarities exist in the results for this study and the preceding one, several differences in model structures and coefficients were identified in this study. The service measure percent delay was retained for its efficacy in assessing operations on complex two-lane highway facilities (particularly those with signalized intersections), but this paper presents new percent delay-based level-of-service criteria thresholds. This paper also provides additional guidance for facility segmentation in situations in which a speed limit reduction is applied in the vicinity of a signalized intersection. [ABSTRACT FROM AUTHOR]

A primary purpose of health insurance is to protect families from medical expenditure risk. Despite this goal and despite the fact that research has found that Medicaid can crowd out private coverage, little is known about the effect of Medicaid on families' spending patterns. This paper implements a simulated instrumental variables strategy with data from the Consumer Expenditure Survey to estimate the effect of an additional family member becoming eligible for Medicaid on family-level health insurance coverage and spending. The results indicate that an additional family member becoming eligible for Medicaid increases the number of people in the family with Medicaid coverage by about 0.135-0.142 and decreases the likelihood that a family has any medical spending in a quarter by 2.7 percentage points. As previous research often finds with different data sets, I find evidence that Medicaid expansions crowd out some private coverage. Unlike most other data sets, the Consumer Expenditure Survey allows for considering the financial implications of crowd-out. The results indicate that families that transition from private coverage to Medicaid are able to spend significantly less on health insurance expenses, meaning Medicaid expansions can be welfare improving for families even when crowd-out occurs. [ABSTRACT FROM AUTHOR]

Storm-scale and mesocyclone-scale processes occurring contemporaneously with a tornado in the Goshen County, Wyoming, supercell observed on 5 June 2009 during the second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) are examined using ensemble analyses produced by assimilating mobile radar and in situ observations into a high-resolution convection-resolving model. This paper focuses on understanding the evolution of the vertical structure of the storm, the outflow buoyancy, and processes affecting the vertical vorticity and circulation within the mesocyclone that correspond to changes in observed tornado intensity. Tornadogenesis occurs when the low-level mesocyclone is least negatively buoyant relative to the environment, possesses its largest circulation, and is collocated with the largest azimuthally averaged convergence during the analysis period. The average buoyancy, circulation, and convergence within the near-surface mesocyclone (on spatial scales resolved by the model) all decrease as the tornado intensifies and matures. The tornado and its parent low-level mesocyclone both dissipate surrounded by a weakening rear-flank downdraft. The decreasing buoyancy of parcels within the low-level mesocyclone may partly be responsible for the weakening of the updraft surrounding the tornado and decoupling of the mid- and low-level circulation. Although the supply of horizontal vorticity generated in the forward flank of the storm increases throughout the life cycle of the tornado, it is presumably less easily tilted and stretched on the mesocyclone-scale during tornado maturity owing to the disruption of the low-level updraft/downdraft structure. Changes in radar-measured tornado intensity lag those of ensemble Kalman filter (EnKF) mesocyclone vorticity and circulation. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study that incorporates computer simulations in teaching linear scheduling concepts and techniques, in a civil engineering course, 'Construction Planning and Scheduling.' The effect of the use of computer simulations in the course shows that the students who were taught with simulation gained a better understanding of linear scheduling concepts and techniques than those students taught without simulation. The data and analysis leading to this finding are presented and discussed in this paper. Two groups of students were considered in this research: (1) civil engineering students from the Department of Civil and Coastal Engineering at the University of Florida and (2) civil engineering students from the Department of Civil Engineering at the University of Chile. Each group was randomly separated into two subgroups: one subgroup was taught by using the traditional method of linear scheduling (without the use of computer simulation) and the other subgroup was taught by using simulations. At the end of the teaching period, the students in both subgroups answered an objective test-type questionnaire specifically designed to address their understanding of linear scheduling techniques. They were also required, in a more subjective way, to provide their evaluation of the teaching method involved. To assess the effect of incorporating computer simulation in teaching linear scheduling, the students' evaluations and answers to the questionnaire were statistically compared. The analysis of the responses showed significant differences between the students' understanding of the subject by using the two teaching methods, with the use of computer simulation shown to be a more effective teaching tool for linear scheduling techniques. [ABSTRACT FROM AUTHOR]

This paper presents FEKO and NEC-2 simulations done on three dipole-like structures; the big blade, the tied-fork and the fork antenna. These antenna elements are considered for the design of the long wavelength array (LWA). The LWA is an interferometer under construction in New Mexico, USA for astronomical observations in the 20 - 80 MHz spectrum. This paper presents the simulation results of a co-polarized antenna gain patterns, impedance values, and mutual couplings for each candidate elements. Coupling results from FEKO and NEC-2 simulations are compared with measurement result of the big blade antenna. The paper also presents 5- parameters for 25 elements of the tied-fork antennas. [ABSTRACT FROM AUTHOR]

If U.S. health care spending growth continues unchecked, the nation will have far less in the future to purchase other essentials, including education, infrastructure, and consumer goods. The point at which nonhealth spending could begin a precipitous decline was previously projected in a paper by Michael Chernew and colleagues to be 2050, unless the rate of health cost growth can be lowered (that is, "bending the curve"). This paper evaluates alternative approaches. First, it looks at the effect on health and nonhealth spending of a one-time reduction in health costs--for example, through a sharp reduction in overuse of medical services in higher-cost regions of the country. It concludes that a one-time reduction in the range of 20-35 percent would delay Chernew's projected decline in nonhealth spending by ten to twenty years. Second, it looks at the effect of combining up-front spending reductions of this size with a longer-range cut in the rate of growth of health spending from 2 percentage points to 1.5 percentage points annually. It finds that this scenario would postpone a major drop in nonhealth spending almost until the twenty-second century. The paper argues that substantial up-front reductions in health spending are therefore worth pursuing to protect the nation's long-term economic growth. [ABSTRACT FROM AUTHOR]

Abstract: The NASA Orbital Debris Engineering Model, ORDEM2000, is in the process of being updated to a new version: ORDEM2008. The data-driven ORDEM covers a spectrum of object size from 10μm to greater than 1m, and ranging from LEO (low Earth orbit) to GEO (geosynchronous orbit) altitude regimes. ORDEM2008 centimeter-sized populations are statistically derived from Haystack and HAX (the Haystack Auxiliary) radar data, while micron-sized populations are estimated from shuttle impact records. Each of the model populations consists of a large number of orbits with specified orbital elements, the number of objects on each orbit (with corresponding uncertainty), and the size, type, and material assignment for each object. This paper describes the general methodology and procedure commonly used in the statistical inference of the ORDEM2008 LEO debris populations. Major steps in the population derivations include data analysis, reference-population construction, definition of model parameters in terms of reference populations, linking model parameters with data, seeking best estimates for the model parameters, uncertainty analysis, and assessment of the outcomes. To demonstrate the population-derivation process and to validate the Bayesian statistical model applied in the population derivations throughout, this paper uses illustrative examples for the special cases of large-size (>1m, >32cm, and >10cm) populations that are tracked by SSN (the Space Surveillance Network) and also monitored by Haystack and HAX radars operating in a staring mode. [Copyright &y& Elsevier]

The specific aim of this paper is to model the vision-posture coupling behavior, which is important for astronauts to stabilize their locomotion in partial gravities as the National Aeronautics and Space Administration plans for manned missions to the Moon and Mars [1]. As such, an optimal scheme is assumed in postural-control processes to stabilize visual optical flows. An experiment was conducted, in which human subjects attended a visual-gait tracking task. In tracking control, head position errors can be used to regulate inputs so that appropriate compensatory changes can be obtained. The "optimal" scheme describes a compromise between postural adjusting efforts and tracking errors. The results show that the proposed optimal-control model describes the gait tracking process more reliably than McRuer's crossover model of the human-plant compensatory behaviors. In practice, if the tracking goal is to be roughly right rather than precisely wrong, this paper also provides the experimental data regarding the human tolerance and achievable performance under various unloading conditions and tracking difficulties. This information and related experimental setup could also be applied to postsurgery gait rehabilitation. [ABSTRACT FROM AUTHOR]

To predict atmospheric conditions in an urban environment, the land surface processes must be accurately described through the use of detailed land use (LU) and land cover (LC) data. Use of the U.S. Geological Survey (USGS) 25-category data, currently in the Fifth-generation Mesoscale Model (MM5), with the Noah land surface model (LSM) and MRF (medium-range forecast) planetary boundary layer (PBL) schemes resulted in the over-prediction of daytime temperatures in the Houston downtown area due to the inaccurate representation as a completely impervious surface. This bias could be corrected with the addition of canopy water in the urban areas from the evapotranspiration effects of urban vegetation. A more fundamental approach would be to utilize an LULC dataset that represents land surface features accurately. The Texas Forest Service (TFS) LULC dataset established with the LANDSAT satellite imagery correctly represents the Houston–Galveston–Brazoria (HGB) area as mixtures of urban, residential, grass, and forest LULC types. This paper describes how the Noah LSM and PBL schemes in the MM5 were modified to accommodate the TFS-LULC data. Comparisons with various meteorological measurements show that the MM5 simulation made with the high resolution LULC data improves the boundary layer mixing conditions and local wind patterns in the Houston Ship Channel, which is a critically important anthropogenic emission area affecting the HGB air pollution problems. In particular, when the synoptic flows are weak, the improved LULC data simulates the asymmetrically elongated Houston heat island convergence zone influencing the location of the afternoon Gulf of Mexico sea-breeze front and the Galveston Bay breeze flows. This paper is part I of a two-part study and focuses on the meteorological simulation. In part II, effects of using the different meteorological inputs on air quality simulations are discussed. [Copyright &y& Elsevier]

This article concerns an investigation of the full scale evacuation of a building with a configuration similar to that of the World Trade Center (WTC) north tower using computer simulation. A range of evacuation scenarios is explored in order to better understand the evacuation of the WTC on 11 September 2001. The analysis makes use of response time data derived from a study of published WTC survivor accounts. Geometric details of the building are obtained from architects' plans while the total building population used in the scenarios is based on estimates produced by the National Institute of Standards and Technology formal investigation into the evacuation. This paper attempts to approximate the events of 11 September 2001 and pursue several 'what if' questions concerning the evacuation. In particular, the study explores the likely outcome had a single staircase survived intact from top to bottom. More generally, this paper explores issues associated with the practical limits of building size that can be expected to be efficiently evacuated using stairs alone. [ABSTRACT FROM AUTHOR]

For a long time emotions have been kept out of the deliberate tools of science; scientists have expressed emotion, but no tools could sense and respond to their affective information. This paper highlights research at the MIT Media Laboratory aimed at giving computers the ability to comfortably sense, recognize, and respond to the human communication of emotion, especially affective states such as frustration, confusion, interest, distress, anger, and joy. Two main themes of sensing--self-report and concurrent expression--are described, together with examples of systems that give users new ways to communicate emotion to computers and, through computers, to other people. In addition to building systems that try to elicit and detect frustration, our research group has built a system that responds to user frustration in a way that appears to help alleviate it. This paper highlights applications of this research to interface design, wearable computing, entertainment, and education, and briefly presents some potential ethical concerns and how they might be addressed. [ABSTRACT FROM AUTHOR]

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]

A web-based Roof Savings Calculator (RSC) has been deployed for the United States Department of Energy as an industry-consensus tool to help building owners, manufacturers, distributors, contractors and researchers easily run complex roof and attic simulations. RSC simulates multiple roof and attic technologies for side-by-side comparison including reflective roofs, different roof slopes, above sheathing ventilation, radiant barriers, low-emittance roof surfaces, duct location, duct leakage rates, multiple substrate types, and insulation levels. Annual simulations of hour-by-hour, whole-building performance are used to provide estimated annual energy and cost savings from reduced HVAC use. While RSC reported similar cooling savings to other simulation engines, heating penalty varied significantly. RSC results show reduced cool roofing cost-effectiveness, thus mitigating expected economic incentives for this countermeasure to the urban heat island effect. This paper consolidates comparison of RSC's projected energy savings to other simulation engines including DOE-2.1E, AtticSim, Micropas, and EnergyPlus. Also included are comparisons to previous simulation-based studies, analysis of RSC cooling savings and heating penalties, the role of radiative heat exchange in an attic assembly, and changes made for increased accuracy of the duct model. Radiant heat transfer and duct interaction not previously modeled is considered a major contributor to heating penalties. [ABSTRACT FROM AUTHOR]

Coalbed methane is a worthwhile potential energy source, because methane gas is eco-friendly and a huge amount of coalbed methane has been buried in the United States, China, Australia, etc. This paper introduces a new simulation model of a vacuum pressure swing adsorption process that has been widely used to purify unconventional gases such as coalbed methane and landfill gas. The developed mathematical model includes a novel interstitial gas velocity equation derived by using a mole balance concept and an overall mass balance equation. The model is verified by comparing with three sets of laboratory-scale (about 0.5 Nm³h-1) experimental data and one set of pilot-scale (100 Nm³h-1) design data. Because the differences between the simulation results and the data are reasonably small, one can conclude that the 200 times scale-up design through the new simulation model is successful. [ABSTRACT FROM AUTHOR]

With vapor compression systems consuming a significant portion of the overall U.S. energy consumption each year, extensive efforts have been made toward the development of control strategies which aim to maximize system efficiency while providing the desired cooling. However, previous control strategies under-utilize a degree of freedom corresponding to the amount of refrigerant in the system, which is related to condenser subcooling and can significantly affect system efficiency. In this paper, an alternative system architecture, which utilizes a receiver and an additional electronic expansion valve, is used to provide independent control of condenser subcooling. Simulation and experimental results show there exists an optimal subcooling which maximizes system efficiency; however, this optimal subcooling changes with operating conditions. Therefore, extremum seeking control is implemented to find the optimal subcooling in an adaptive, model-free manner. Experimental results demonstrate a 9% increase in efficiency using the alternative architecture and extremum seeking control. [ABSTRACT FROM AUTHOR]

Abstract: In order to consider the effect of battery temperature on the total fuel consumption when a Pontryagin's Minimum Principle (PMP)-based power management strategy is applied to a fuel cell hybrid vehicle (FCHV), this paper designates the battery temperature as a second-state variable other than the battery state of charge (SOC) and defines a new costate for the battery temperature in the control problem. The PMP-based power management strategy is implemented in a computer simulation and the relationship among the final values of the two state variables and the total fuel consumption is illustrated based on the simulation results. This relationship is defined as an optimal surface in this research. Using the optimal surface, it can be concluded that considering the battery temperature effect in the PMP-based power management strategy improves the fuel economy of the FCHV. Potential fuel economy gains attributed to consideration of the battery temperature effect are also determined based on the optimal surfaces. [Copyright &y& Elsevier]

Throughout the 70-year history of NASA Glenn Research Center (GRC), technology development efforts that promoted advancement in aeronautics technologies, aerospace sciences, materials for hostile environments, and microgravity physics have also enabled the maturation of technologies that have affected medical practice on Earth, in the air, and in space. GRC's unique skill mix, required for aeronautics research and space exploration, ultimately also advanced the development of a wide array of capabilities applicable to biomedical engineering. This paper presents a historical review of notable biomedical endeavors at GRC that have addressed common and uncommon medical conditions afflicting both astronauts and non-astronauts. It also highlights the unique physiological stressors associated with residing in space. The physiological changes associated with these stimuli present evolving challenges for researchers to devise new and innovative medical interventions and technologies. [ABSTRACT FROM AUTHOR]

Abstract: The French Alternative Energies and Atomic Energy Commission (CEA) is conducting an R&D program to improve the characterization of long lived and medium activity radioactive waste packages with nondestructive nuclear measurements. Neutron interrogation with the “Associated Particle Technique” (APT), which brings 3D information about waste materials composition, was studied by numerical simulation with the MCNP computer code [1] and MODAR data analysis software [2]. The design of the system is first presented, especially shields and collimators used to limit the detectors count rate because of the intense gamma emission of the waste. The random background due to the neutron generator was also limited by a specific shield as recommended earlier [3]. Then the paper presents numerical simulations illustrating the ability of APT to characterize specific volumes of interest filled with different materials (iron, water, aluminum, PVC, oil) in different waste packages. Main limitations are also identified, such as neutron scattering in the dense, hydrogenous waste matrices. [Copyright &y& Elsevier]

Abstract: Industrial fire and explosion hazards due to accidents in fuel storage units have gained a considerable attention in recent years. Both, the regulatory bodies and scientific communities are heavily concerned about the proper safety measures to avoid such calamities in the future. This paper aims to bring some essentials related to the hazards that arose from recent fuel storage fire accidents occurring in Buncefield, UK (2005), Puerto Rico, USA (2009) and Sitapura, India (2009). The potential similarities behind occurrence of these accidents are studied. The applicability of various methods (models) and also computer simulations to estimate the safety distances according to the international standards for both explosion and fire hazard are verified. The overpressures caused by the Vapor Cloud Explosions (VCE) and radiation fluxes emitted by the fires are considered for respective explosion and fire hazard estimations. The prime focus is placed on the regulations laid down by the National Fire Protection Agency of the United States and the European Norms. [Copyright &y& Elsevier]

Abstract: Breakup model is the key area of space debris environment modeling. NASA standard breakup model is currently the most widely used for general-purpose. It is a statistical model found based on space surveillance data and a few ground-based test data. NASA model takes the mass, impact velocity magnitude for input and provides the fragment size, area-to-mass ratio, velocity magnitude distributions for output. A more precise approach for spacecraft disintegration fragment analysis is presented in this paper. This approach is based on hypervelocity impact dynamics and takes the shape, material, internal structure and impact location etc. of spacecraft and impactor, which might greatly affect the fragment distribution, into consideration. The approach is a combination of finite element and particle methods, entitled finite element reconstruction (FER). By reconstructing elements from the particle debris cloud, reliable individual fragments are identified. Fragment distribution is generated with undirected graph conversion and connected component analysis. Ground-based test from literature is introduced for verification. In the simulation satellite targets and impactors are modeled in detail including the shape, material, internal structure and so on. FER output includes the total number of fragments and the mass, size and velocity vector of each fragment. The reported fragment distribution of FER shows good agreement with the test, and has good accuracy for small fragments. [Copyright &y& Elsevier]

Abstract: In order to economically gain the maximum energy from the wind turbine, the performance of the blade profile must be obtained. In this paper, the results of aerodynamic simulations of the steady low-speed flow past two-dimensional S-series wind-turbine-blade profiles, developed by the National Renewable Energy Laboratory (NREL), are presented. The aerodynamic simulations were performed using a Computational Fluid Dynamics (CFD) method based on the finite-volume approach. The governing equations used in the simulations are the Reynolds-Averaged-Navier–Stokes (RANS) equations. The wind conditions during the simulations were developed from the wind speeds over different sites in Egypt. The lift and drag forces are the most important parameters in studying the wind-turbine performance. Therefore, an attempt to study the lift and drag forces on the wind turbine blades at various sections is presented. The maximum sliding ratio (lift/drag ratio) is desired in order to gain the maximum power from the wind turbine. The performance of different blade profiles at different wind speeds was investigated and the optimum blade profile for each wind speed is determined based on the maximum sliding ratio. Moreover, the optimum Angle Of Attack (AOA) for each blade profile is determined at the different wind speeds. The numerical results are benchmarked against wind tunnel measurements. The comparisons show that the CFD code used in this study can accurately predict the wind-turbine blades aerodynamic loads. [Copyright &y& Elsevier]

Based on analyses of the relationship between Pacific Meridional Mode (PMM) and number of tropical cyclones (TCs) activity over the western North Pacific, the impacts of the PMM on Tc activity over the western North Pacific are studied using numerical simulations with an Atmospheric General Circulation Model (CAM3) of National Center for Atmospheric Research (of USA). The result shows that the PMM has impacts on the large-scale generating environment of TCs, thus affecting their number and strength. The numerical simulations using the NCAR CAM3 indicate that with the inclusion of the forcing from sea surface temperature (SST) of the PMM, there appears a decreased magnitude of the vertical zonal wind shear, large proportion of relative humidity, anomalous westerly wind at low levels and anomalous easterly wind at high levels, in association with anomalous cyclonic circulation at low levels and anomalous anti-cyclonic circulation at high levels over the tropical western Pacific. Thus, the PMM provides favorable environment for the typhoon genesis. In the sensitivity experiment, TCs have larger strength, lower SST at the center, stronger tangential wind at 850 hPa and intensified warm cores at high levels. In this paper, the simulation results are similar to that in the data analyses, which reveals the important impact of the PMM on TC activity over the western North Pacific. [ABSTRACT FROM AUTHOR]

The National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program provides a rich source of data stratified according to tumor biomarkers that play an important role in cancer surveillance research. These data are useful for analyzing trends in cancer incidence and survival. These tumor markers, however, are often prone to missing observations. To address the problem of missing data, the authors employed sequential regression multivariate imputation for breast cancer variables, with a particular focus on estrogen receptor status, using data from 13 SEER registries covering the period 1992–2007. In this paper, they present an approach to accounting for missing information through the creation of imputed data sets that can be analyzed using existing software (e.g., SEER*Stat) developed for analyzing cancer registry data. Bias in age-adjusted trends in female breast cancer incidence is shown graphically before and after imputation of estrogen receptor status, stratified by age and race. The imputed data set will be made available in SEER*Stat (http://seer.cancer.gov/analysis/index.html) to facilitate accurate estimation of breast cancer incidence trends. To ensure that the imputed data set is used correctly, the authors provide detailed, step-by-step instructions for conducting analyses. This is the first time that a nationally representative, population-based cancer registry data set has been imputed and made available to researchers for conducting a variety of analyses of breast cancer incidence trends. [ABSTRACT FROM PUBLISHER]

Abstract: Coalbed methane (CBM) formations provides a considerable amount of the US natural gas production and have the potential of storing significant amounts of carbon dioxide (CO2) through enhanced gas recovery operations. Enhanced coalbed methane (ECBM) recovery by injection of CO2 or a mixture of CO2 and nitrogen (N2) has been proven to recover additional natural gas resources. However, since coalbeds are normally saturated with water and can be in communication with an aquifer, a large amount of water is often co-produced during the natural gas extraction. The conventional approach for CBM production relies on the reduction of the gas partial pressure in the coal seam. This can be accomplished by either pumping the formation water to the surface and/or by injecting gases such as N2 and CO2. Disposal of the produced water is an environmental challenge as harmful impurities must be removed by appropriate purification techniques. Consequently, a reduction of water production in CBM operations is desirable. In this paper we present a numerical investigation of the potential reduction in water production during ECBM operations that are commonly used to increase methane (CH4) recovery. We use a three-dimensional coalbed model with an aquifer located at the bottom to investigate the amounts of gas and water produced in ECBM operations per volume of coal seam as a function of aquifer strength and sorption characteristics including sorption induced strain. The amount of gas/water that is produced varies significantly depending on the aquifer strength and injection gas composition. We demonstrate that injection of CO2 and/or N2 in some settings reduces the water handling problem substantially. CBM is an important worldwide energy source with a large number of formations being excellent candidates for ECBM recovery processes. Our analysis of the interplay between coal characteristics, aquifer support and the resultant behavior in terms of gas/water production provides valuable input for optimization of future planning and operations. [Copyright &y& Elsevier]

Abstract: Thermal mass combined with other passive strategies can play an important role in buildings energy efficiency, minimizing the need of space-conditioning mechanical systems. However, the use of lightweight materials with low thermal mass is becoming increasingly common. Phase Change Materials (PCMs) can add thermal energy storage benefits to lightweight constructions. There are many studies about the use of PCM in buildings, but there are still some difficulties for effective use and practical application of these materials. The study of applications used in real buildings could help us find solutions to these difficulties. This paper analyzed different PCM applications presented in highly efficient lightweight construction houses that have participated in the American Solar Decathlon, an international competition organized by U.S. Department of Energy. These houses have been tested and monitored in Washington DC, place with suitable climate conditions for short term thermal storage systems. The study started with a classification of the PCM applications and included an analysis of the systems, materials, switching temperatures, containments and design strategies used to improve the houses energy performance. Also, it included results of numerical simulations and experimentation that the participant team had done, complemented with information available in the literature about similar materials or applications. [Copyright &y& Elsevier]

Abstract: In this paper, we present the PolyMAX module which enhances network simulator 2 (ns-2), the most popular network simulator used in academia, to provide one of the most complete simulation tools to evaluate the performance of Mobile WiMAX networks. PolyMAX is based on the National Institute of Standards and Technology (NIST) module and our specific contributions consist on the design and implementation of the Quality of Service (QoS) classes and QoS management messages, the uplink access grant-request mechanisms, Adaptive Modulation and Coding, and a scheduler handling all five WiMAX QoS classes. We also present validation results for the different components of our module and typical WiMAX simulation scenarios illustrating its flexibility and some of its features. The PolyMAX module represents an important tool enabling researchers to easily implement their Mobile WiMAX scheduling and Adaptive Modulation and Coding (AMC) algorithms and accurately evaluate their performance for realistic scenarios. [Copyright &y& Elsevier]

Abstract: This paper identifies the impact of thermostat strategies on heating and cooling energy consumptions in buildings, thus suggesting the importance of a database for understanding the effect of thermostat settings and for deciding energy-conscious strategies. Using computer simulation, diverse thermostat strategies – change of setback period, change of set-point temperature, and change of setback temperature – were tested parametrically in a typical USA single-family homes, located in two climate zones, namely cold (Detroit, Michigan) and hot-humid (Miami, Florida). Analysis revealed that heating and cooling systems were significant energy-consuming components in each climate zone. Accordingly, heating energy in cold climate zones and cooling energy in hot-humid climate zones have potential for matchingly significant saving. Diverse thermostat strategies (changes of setback period, of set-point, of setback temperature) demonstrated their obvious impacts on such saving. In the cold climate in particular, the heating system showed the most significant energy-saving effect via proper thermostat strategies. Proper setback period, set-point and setback temperature need to be established to achieve energy efficiency in residential buildings. [ABSTRACT FROM AUTHOR]

Most of the existing technical trading rules are linear in nature. This paper investigates the predictability of nonlinear time series model based trading strategies in the U.S. stock market. The performance of the nonlinear trading rule is compared with that of the linear model based rules. It is found that the self-exciting threshold autoregressive (SETAR) model based trading rules perform slightly better than the AR rules for the Dow Jones and Standard and Poor 500, while the AR rules perform slightly better in the NASDAQ market. Both the SETAR and the AR rules outperform the VMA rules. The results are confirmed by bootstrap simulations. [ABSTRACT FROM AUTHOR]

Modelling of contaminant transport on watersheds is a problem of concern with regard to the protection of water ecosystems. This paper presents a numerical model, using the finite element method, to simulate contaminant transport hydrodynamics. Spatial and temporal progression of a spilled toxic substance was compiled for the Macks-Creek basin located in United States. It is shown that the developed tool, based on coupled terrain and surface runoff models, provided adequate results in terms of runoff velocities and height. Results from this compute served as an input of a computer based system that we developed to simulate the real-time contaminant behaviour and spreading since its spillage. The developed model can be used in both simulating and forecasting modes. Obtained predictions are of practical relevance to hydrologists and water resources managers for applications in environmental management strategies during infrastructure and urban planning phases as well. [ABSTRACT FROM AUTHOR]

This paper presents updated national health spending projections for 2009-2019 that take into account recent comprehensive health reform legislation and other relevant changes in law and regulations. Relative to our February 2010 projections under prior law, average annual growth in national health spending over the projection period is estimated to be 0.2 percentage point higher than our previous estimate. The health care share of gross domestic product (GDP) is expected to be 0.3 percentage point higher in 2019. Within these net overall impacts are larger differences for trends in spending and spending growth by payer, attributable to reform's many major changes to health care coverage and financing. [ABSTRACT FROM AUTHOR]

Kathleen Sebelius, secretary of health and human services, has issued a challenge to enroll the millions of uninsured children eligible for public insurance in Medicaid or the Children's Health Insurance Program (CHIP). This paper provides estimates of the rates at which children in the various states participated in these programs in 2008 as well as the number who were eligible for them but uninsured. According to our coverage estimates, an estimated 7.3 million children were uninsured on an average day in 2008, of whom 4.7 million (65 percent) were eligible for Medicaid or CHIP but not enrolled. Participation rates varied across states from 55 percent to 95 percent, and ten states had participation rates close to or above 90 percent. Thirty-nine percent of eligible uninsured children (1.8 million) live in just three states--California, Texas, and Florida--and 61 percent (2.9 million) live in ten states. Meeting Secretary Sebelius's challenge means achieving success in these populous states, in part through tools and resources available under the 2009 CHIP reauthorization law. [ABSTRACT FROM AUTHOR]

The emerging field of computational toxicology applies mathematical and computer models and molecular biological and chemical approaches to explore both qualitative and quantitative relationships between sources of environmental pollutant exposure and adverse health outcomes. The integration of modern computing with molecular biology and chemistry will allow scientists to better prioritize data, inform decision makers on chemical risk assessments and understand a chemical's progression from the environment to the target tissue within an organism and ultimately to the key steps that trigger an adverse health effect. In this paper, several of the major research activities being sponsored by Environmental Protection Agency's National Center for Computational Toxicology are highlighted. Potential links between research in computational toxicology and human exposure science are identified. As with the traditional approaches for toxicity testing and hazard assessment, exposure science is required to inform design and interpretation of high-throughput assays. In addition, common themes inherent throughout National Center for Computational Toxicology research activities are highlighted for emphasis as exposure science advances into the 21st century. [ABSTRACT FROM AUTHOR]

In this paper, numerical simulations of tornadoes are presented. The problem considered is to first simulate numerically a tornado-like vortex passing through a populated area and then analyse the paths as it impacts structures. This study was invigorated after a tornado, classified F2 on the Fujita scale, striked Embry-Riddle Aeronautical University Daytona Beach Campus in December 2006. The computational domain used in this study is the Florida ERAU Campus and includes accurately all the different buildings. Computations of turbulent flow around several complex shaped buildings are performed using a k-ε turbulence model. The tornado is modelled by means of a vortex which is generated using a pressure gradient. The results obtained are physically reasonable and serve as a first step towards modelling tornadoes. [ABSTRACT FROM AUTHOR]