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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: 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: 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]

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]

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: 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: 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: 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: 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: 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]