Automatic generation and simulation of urban building energy models based on city datasets for city-scale building retrofit analysis

DOE PAGES

Chen, Yixing; Hong, Tianzhen; Piette, Mary Ann

2017-08-07

Buildings in cities consume 30–70% of total primary energy, and improving building energy efficiency is one of the key strategies towards sustainable urbanization. Urban building energy models (UBEM) can support city managers to evaluate and prioritize energy conservation measures (ECMs) for investment and the design of incentive and rebate programs. This paper presents the retrofit analysis feature of City Building Energy Saver (CityBES) to automatically generate and simulate UBEM using EnergyPlus based on cities’ building datasets and user-selected ECMs. CityBES is a new open web-based tool to support city-scale building energy efficiency strategic plans and programs. The technical details ofmore » using CityBES for UBEM generation and simulation are introduced, including the workflow, key assumptions, and major databases. Also presented is a case study that analyzes the potential retrofit energy use and energy cost savings of five individual ECMs and two measure packages for 940 office and retail buildings in six city districts in northeast San Francisco, United States. The results show that: (1) all five measures together can save 23–38% of site energy per building; (2) replacing lighting with light-emitting diode lamps and adding air economizers to existing heating, ventilation and air-conditioning (HVAC) systems are most cost-effective with an average payback of 2.0 and 4.3 years, respectively; and (3) it is not economical to upgrade HVAC systems or replace windows in San Francisco due to the city's mild climate and minimal cooling and heating loads. Furthermore, the CityBES retrofit analysis feature does not require users to have deep knowledge of building systems or technologies for the generation and simulation of building energy models, which helps overcome major technical barriers for city managers and their consultants to adopt UBEM.« less

Fast Learning for Immersive Engagement in Energy Simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bush, Brian W; Bugbee, Bruce; Gruchalla, Kenny M

The fast computation which is critical for immersive engagement with and learning from energy simulations would be furthered by developing a general method for creating rapidly computed simplified versions of NREL's computation-intensive energy simulations. Created using machine learning techniques, these 'reduced form' simulations can provide statistically sound estimates of the results of the full simulations at a fraction of the computational cost with response times - typically less than one minute of wall-clock time - suitable for real-time human-in-the-loop design and analysis. Additionally, uncertainty quantification techniques can document the accuracy of the approximate models and their domain of validity. Approximationmore » methods are applicable to a wide range of computational models, including supply-chain models, electric power grid simulations, and building models. These reduced-form representations cannot replace or re-implement existing simulations, but instead supplement them by enabling rapid scenario design and quality assurance for large sets of simulations. We present an overview of the framework and methods we have implemented for developing these reduced-form representations.« less

Design and development of Building energy simulation Software for prefabricated cabin type of industrial building (PCES)

NASA Astrophysics Data System (ADS)

Zhang, Jun; Li, Ri Yi

2018-06-01

Building energy simulation is an important supporting tool for green building design and building energy consumption assessment, At present, Building energy simulation software can't meet the needs of energy consumption analysis and cabinet level micro environment control design of prefabricated building. thermal physical model of prefabricated building is proposed in this paper, based on the physical model, the energy consumption calculation software of prefabricated cabin building(PCES) is developed. we can achieve building parameter setting, energy consumption simulation and building thermal process and energy consumption analysis by PCES.

Using Delft3D to Simulate Current Energy Conversion

NASA Astrophysics Data System (ADS)

James, S. C.; Chartrand, C.; Roberts, J.

2015-12-01

As public concern with renewable energy increases, current energy conversion (CEC) technology is being developed to optimize energy output and minimize environmental impact. CEC turbines generate energy from tidal and current systems and create wakes that interact with turbines located downstream of a device. The placement of devices can greatly influence power generation and structural reliability. CECs can also alter the ecosystem process surrounding the turbines, such as flow regimes, sediment dynamics, and water quality. Software is needed to investigate specific CEC sites to simulate power generation and hydrodynamic responses of a flow through a CEC turbine array. This work validates Delft3D against several flume experiments by simulating the power generation and hydrodynamic response of flow through a turbine or actuator disc(s). Model parameters are then calibrated against these data sets to reproduce momentum removal and wake recovery data with 3-D flow simulations. Simulated wake profiles and turbulence intensities compare favorably to the experimental data and demonstrate the utility and accuracy of a fast-running tool for future siting and analysis of CEC arrays in complex domains.

Guidelines for the analysis of free energy calculations.

PubMed

Klimovich, Pavel V; Shirts, Michael R; Mobley, David L

2015-05-01

Free energy calculations based on molecular dynamics simulations show considerable promise for applications ranging from drug discovery to prediction of physical properties and structure-function studies. But these calculations are still difficult and tedious to analyze, and best practices for analysis are not well defined or propagated. Essentially, each group analyzing these calculations needs to decide how to conduct the analysis and, usually, develop its own analysis tools. Here, we review and recommend best practices for analysis yielding reliable free energies from molecular simulations. Additionally, we provide a Python tool, alchemical-analysis.py, freely available on GitHub as part of the pymbar package (located at http://github.com/choderalab/pymbar), that implements the analysis practices reviewed here for several reference simulation packages, which can be adapted to handle data from other packages. Both this review and the tool covers analysis of alchemical calculations generally, including free energy estimates via both thermodynamic integration and free energy perturbation-based estimators. Our Python tool also handles output from multiple types of free energy calculations, including expanded ensemble and Hamiltonian replica exchange, as well as standard fixed ensemble calculations. We also survey a range of statistical and graphical ways of assessing the quality of the data and free energy estimates, and provide prototypes of these in our tool. We hope this tool and discussion will serve as a foundation for more standardization of and agreement on best practices for analysis of free energy calculations.

Guidelines for the analysis of free energy calculations

PubMed Central

Klimovich, Pavel V.; Shirts, Michael R.; Mobley, David L.

2015-01-01

Free energy calculations based on molecular dynamics (MD) simulations show considerable promise for applications ranging from drug discovery to prediction of physical properties and structure-function studies. But these calculations are still difficult and tedious to analyze, and best practices for analysis are not well defined or propagated. Essentially, each group analyzing these calculations needs to decide how to conduct the analysis and, usually, develop its own analysis tools. Here, we review and recommend best practices for analysis yielding reliable free energies from molecular simulations. Additionally, we provide a Python tool, alchemical–analysis.py, freely available on GitHub at https://github.com/choderalab/pymbar–examples, that implements the analysis practices reviewed here for several reference simulation packages, which can be adapted to handle data from other packages. Both this review and the tool covers analysis of alchemical calculations generally, including free energy estimates via both thermodynamic integration and free energy perturbation-based estimators. Our Python tool also handles output from multiple types of free energy calculations, including expanded ensemble and Hamiltonian replica exchange, as well as standard fixed ensemble calculations. We also survey a range of statistical and graphical ways of assessing the quality of the data and free energy estimates, and provide prototypes of these in our tool. We hope these tools and discussion will serve as a foundation for more standardization of and agreement on best practices for analysis of free energy calculations. PMID:25808134

Comparison of tropical cyclogenesis processes in climate model and cloud-resolving model simulations using moist static energy budget analysis

NASA Astrophysics Data System (ADS)

Wing, Allison; Camargo, Suzana; Sobel, Adam; Kim, Daehyun; Murakami, Hiroyuki; Reed, Kevin; Vecchi, Gabriel; Wehner, Michael; Zarzycki, Colin; Zhao, Ming

2017-04-01

In recent years, climate models have improved such that high-resolution simulations are able to reproduce the climatology of tropical cyclone activity with some fidelity and show some skill in seasonal forecasting. However biases remain in many models, motivating a better understanding of what factors control the representation of tropical cyclone activity in climate models. We explore the tropical cyclogenesis processes in five high-resolution climate models, including both coupled and uncoupled configurations. Our analysis framework focuses on how convection, moisture, clouds and related processes are coupled and employs budgets of column moist static energy and the spatial variance of column moist static energy. The latter was originally developed to study the mechanisms of tropical convective organization in idealized cloud-resolving models, and allows us to quantify the different feedback processes responsible for the amplification of moist static energy anomalies associated with the organization of convection and cyclogenesis. We track the formation and evolution of tropical cyclones in the climate model simulations and apply our analysis both along the individual tracks and composited over many tropical cyclones. We then compare the genesis processes; in particular, the role of cloud-radiation interactions, to those of spontaneous tropical cyclogenesis in idealized cloud-resolving model simulations.

Technical Highlight: NREL Improves Building Energy Simulation Programs Through Diagnostic Testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Polly, B.

2012-01-09

This technical highlight describes NREL research to develop Building Energy Simulation Test for Existing Homes (BESTEST-EX) to increase the quality and accuracy of energy analysis tools for the building retrofit market.

Energy simulation and optimization for a small commercial building through Modelica

NASA Astrophysics Data System (ADS)

Rivas, Bryan

Small commercial buildings make up the majority of buildings in the United States. Energy consumed by these buildings is expected to drastically increase in the next few decades, with a large percentage of the energy consumed attributed to cooling systems. This work presents the simulation and optimization of a thermostat schedule to minimize energy consumption in a small commercial building test bed during the cooling season. The simulation occurs through the use of the multi-engineering domain Dymola environment based on the Modelica open source programming language and is optimized with the Java based optimization program GenOpt. The simulation uses both physically based modeling utilizing heat transfer principles for the building and regression analysis for energy consumption. GenOpt is dynamically coupled to Dymola through various interface files. There are very few studies that have coupled GenOpt to a building simulation program and even fewer studies have used Dymola for building simulation as extensively as the work presented here. The work presented proves Dymola as a viable alternative to other building simulation programs such as EnergyPlus and MatLab. The model developed is used to simulate the energy consumption of a test bed, a commissioned real world small commercial building, while maintaining indoor thermal comfort. Potential applications include smart or intelligent building systems, predictive simulation of small commercial buildings, and building diagnostics.

A novel method for energy harvesting simulation based on scenario generation

NASA Astrophysics Data System (ADS)

Wang, Zhe; Li, Taoshen; Xiao, Nan; Ye, Jin; Wu, Min

2018-06-01

Energy harvesting network (EHN) is a new form of computer networks. It converts ambient energy into usable electric energy and supply the electrical energy as a primary or secondary power source to the communication devices. However, most of the EHN uses the analytical probability distribution function to describe the energy harvesting process, which cannot accurately identify the actual situation for the lack of authenticity. We propose an EHN simulation method based on scenario generation in this paper. Firstly, instead of setting a probability distribution in advance, it uses optimal scenario reduction technology to generate representative scenarios in single period based on the historical data of the harvested energy. Secondly, it uses homogeneous simulated annealing algorithm to generate optimal daily energy harvesting scenario sequences to get a more accurate simulation of the random characteristics of the energy harvesting network. Then taking the actual wind power data as an example, the accuracy and stability of the method are verified by comparing with the real data. Finally, we cite an instance to optimize the network throughput, which indicate the feasibility and effectiveness of the method we proposed from the optimal solution and data analysis in energy harvesting simulation.

A simulation of high energy cosmic ray propagation 1

NASA Technical Reports Server (NTRS)

Honda, M.; Kifune, T.; Matsubara, Y.; Mori, M.; Nishijima, K.; Teshima, M.

1985-01-01

High energy cosmic ray propagation of the energy region 10 to the 14.5 power - 10 to the 18th power eV is simulated in the inter steller circumstances. In conclusion, the diffusion process by turbulent magnetic fields is classified into several regions by ratio of the gyro-radius and the scale of turbulence. When the ratio becomes larger then 10 to the minus 0.5 power, the analysis with the assumption of point scattering can be applied with the mean free path E sup 2. However, when the ratio is smaller than 10 to the minus 0.5 power, we need a more complicated analysis or simulation. Assuming the turbulence scale of magnetic fields of the Galaxy is 10-30pc and the mean magnetic field strength is 3 micro gauss, the energy of cosmic ray with that gyro-radius is about 10 to the 16.5 power eV.

Analysis and Optimization of Building Energy Consumption

NASA Astrophysics Data System (ADS)

Chuah, Jun Wei

Energy is one of the most important resources required by modern human society. In 2010, energy expenditures represented 10% of global gross domestic product (GDP). By 2035, global energy consumption is expected to increase by more than 50% from current levels. The increased pace of global energy consumption leads to significant environmental and socioeconomic issues: (i) carbon emissions, from the burning of fossil fuels for energy, contribute to global warming, and (ii) increased energy expenditures lead to reduced standard of living. Efficient use of energy, through energy conservation measures, is an important step toward mitigating these effects. Residential and commercial buildings represent a prime target for energy conservation, comprising 21% of global energy consumption and 40% of the total energy consumption in the United States. This thesis describes techniques for the analysis and optimization of building energy consumption. The thesis focuses on building retrofits and building energy simulation as key areas in building energy optimization and analysis. The thesis first discusses and evaluates building-level renewable energy generation as a solution toward building energy optimization. The thesis next describes a novel heating system, called localized heating. Under localized heating, building occupants are heated individually by directed radiant heaters, resulting in a considerably reduced heated space and significant heating energy savings. To support localized heating, a minimally-intrusive indoor occupant positioning system is described. The thesis then discusses occupant-level sensing (OLS) as the next frontier in building energy optimization. OLS captures the exact environmental conditions faced by each building occupant, using sensors that are carried by all building occupants. The information provided by OLS enables fine-grained optimization for unprecedented levels of energy efficiency and occupant comfort. The thesis also describes a retrofit

Database for Simulation of Electron Spectra for Surface Analysis (SESSA)Database for Simulation of Electron Spectra for Surface Analysis (SESSA)

National Institute of Standards and Technology Data Gateway

SRD 100 Database for Simulation of Electron Spectra for Surface Analysis (SESSA)Database for Simulation of Electron Spectra for Surface Analysis (SESSA) (PC database for purchase)   This database has been designed to facilitate quantitative interpretation of Auger-electron and X-ray photoelectron spectra and to improve the accuracy of quantitation in routine analysis. The database contains all physical data needed to perform quantitative interpretation of an electron spectrum for a thin-film specimen of given composition. A simulation module provides an estimate of peak intensities as well as the energy and angular distributions of the emitted electron flux.

Energy consumption analysis and simulation of waste heat recovery technology of ceramic rotary kiln

NASA Astrophysics Data System (ADS)

Chen, Zhiguang; Zhou, Yu; Qin, Chaokui; Zhang, Xuemei

2018-03-01

Ceramsite is widely used in the construction industry, insulation works and oil industry in China, and the manufacture equipment is mainly industrial kiln. In this paper, energy consumption analysis had been carried out through experimental test of a Ceramsite kiln in Henan province. Results showed that the discharge temperature of Ceramsite was about 1393K, and the waste heat accounted for 22.1% of the total energy consumption. A structure of cyclone preheater which recovered waste heat of the high temperature Ceramsite by blast cooling was designed. Then, using Fluent software, performance of the unit was simulated. The minimum temperature that Ceramsite could reach, heat dissipating capacity of Ceramsite, temperature at air outlet, wall temperature of the unit and pressure loss were analyzed. Performance of the designed unit under different inlet velocity was analyzed as well.

Aircraft Rollout Iterative Energy Simulation

NASA Technical Reports Server (NTRS)

Kinoshita, L.

1986-01-01

Aircraft Rollout Iterative Energy Simulation (ARIES) program analyzes aircraft-brake performance during rollout. Simulates threedegree-of-freedom rollout after nose-gear touchdown. Amount of brake energy dissipated during aircraft landing determines life expectancy of brake pads. ARIES incorporates brake pressure, actual flight data, crosswinds, and runway characteristics to calculate following: brake energy during rollout for up to four independent brake systems; time profiles of rollout distance, velocity, deceleration, and lateral runway position; and all aerodynamic moments on aircraft. ARIES written in FORTRAN 77 for batch execution.

A Labor Market Analysis of the Electricity Sector for 2030 using the National Energy with Weather System Simulator

NASA Astrophysics Data System (ADS)

Terry, L.; Clack, C.; Marquis, M.; Paine, J.; Picciano, P.

2015-12-01

We conducted an analysis that utilized the National Renewable Energy Laboratory's (NREL) Jobs and Economic Development Impact (JEDI) models to estimate the temporary and permanent jobs, earnings, and state sales tax revenues that would be created by various scenarios of the National Energy with Weather System (NEWS) simulator. This simulator was created by a collaboration between the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado and the Earth Systems Research Laboratory (ESRL NOAA). The NEWS simulator used three years of high-resolution (13-km, hourly) weather and power data to select the most cost-efficient, resource-maximizing, and complementary locations for wind, solar photovoltaic, and natural gas power plants along with high-voltage direct-current transmission, thereby providing the cheapest possible electricity grid that facilitates the incorporation of large amounts of wind and solar PV. We applied various assumptions to ensure that we produced conservative estimates, while keeping costs in line with those of the NEWS simulator. Our analysis shows that under the lowest carbon-emitting scenario of the NEWS carried out (80% reduction in CO2 compared with 1990 levels), almost ten million new jobs could be created by 2030. Of those jobs, over 400,000 would be permanently supporting the operations of the power plants. That particular scenario would also add over 500 billion to the paychecks of American workers and 75 billion to state tax revenues by 2030. All of this is achieved with average electricity costs of 10.7¢/kWh, because the electric system relies less heavily on fuel and more on jobs constructing, operating, and maintaining infrastructure. We use the current presentation to describe the methods used to reach these findings and examine some potential impacts of our estimates on public policy. Although we are able to identify some systematic problems with the JEDI model, we find that these problems

The perceived value of using BIM for energy simulation

NASA Astrophysics Data System (ADS)

Lewis, Anderson M.

Building Information Modeling (BIM) is becoming an increasingly important tool in the Architectural, Engineering & Construction (AEC) industries. Some of the benefits associated with BIM include but are not limited to cost and time savings through greater trade and design coordination, and more accurate estimating take-offs. BIM is a virtual 3D, parametric design software that allows users to store information of a model within and can be used as a communication platform between project stakeholders. Likewise, energy simulation is an integral tool for predicting and optimizing a building's performance during design. Creating energy models and running energy simulations can be a time consuming activity due to the large number of parameters and assumptions that must be addressed to achieve reasonably accurate results. However, leveraging information imbedded within Building Information Models (BIMs) has the potential to increase accuracy and reduce the amount of time required to run energy simulations and can facilitate continuous energy simulations throughout the design process, thus optimizing building performance. Although some literature exists on how design stakeholders perceive the benefits associated with leveraging BIM for energy simulation, little is known about how perceptions associated with leveraging BIM for energy simulation differ between various green design stakeholder user groups. Through an e-survey instrument, this study seeks to determine how perceptions of using BIMs to inform energy simulation differ among distinct design stakeholder groups, which include BIM-only users, energy simulation-only users and BIM and energy simulation users. Additionally, this study seeks to determine what design stakeholders perceive as the main barriers and benefits of implementing BIM-based energy simulation. Results from this study suggest that little to no correlation exists between green design stakeholders' perceptions of the value associated with using

BLAST: Building energy simulation in Hong Kong

NASA Astrophysics Data System (ADS)

Fong, Sai-Keung

1999-11-01

evaluated. It was found that the supply of cool air to the lower portion of the compartment provided significant performance of space cooling. The mathematical relationships between different shading patterns and different glass window to wall ratios of single compartments were established to provide a guide for easy approximation of energy use under similar conditions. In addition, the Overall Thermal Transfer Values (OTTV) for the compartments were studied. The monthly and annual energy use of three realistic buildings were investigated. They were a commercial building, an industrial building and a dual-purpose building. The cooling loads per floor area for the buildings were studied and the OTTV were evaluated by two different methods. Sensitivity analysis was carried out to investigate the impact of the parameters of internal heat gains on the energy use of an academic building. It was found that there was major influence of indoor temperature setting on building energy use The performances of using the local weather data file of TMY and example weather years 1980 and 1989 were evaluated. TMY was found to be the most suitable for energy simulation while the weather years 1980 and 1989 yielded good results.

Grid connected integrated community energy system. Phase II: final state 2 report. Cost benefit analysis, operating costs and computer simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1978-03-22

A grid-connected Integrated Community Energy System (ICES) with a coal-burning power plant located on the University of Minnesota campus is planned. The cost benefit analysis performed for this ICES, the cost accounting methods used, and a computer simulation of the operation of the power plant are described. (LCL)

The Energy-Environment Simulator as a Classroom Aid.

ERIC Educational Resources Information Center

Sell, Nancy J.; Van Koevering, Thomas E.

1981-01-01

Describes the use, availability, and flexibility of the Energy-Environment Simulator, a specially designed analog computer which simulates the real-world energy situation and which is programed with estimated United States and world supplies of energy sources and estimated United States energy demands. (MP)

Discrete kinetic models from funneled energy landscape simulations.

PubMed

Schafer, Nicholas P; Hoffman, Ryan M B; Burger, Anat; Craig, Patricio O; Komives, Elizabeth A; Wolynes, Peter G

2012-01-01

A general method for facilitating the interpretation of computer simulations of protein folding with minimally frustrated energy landscapes is detailed and applied to a designed ankyrin repeat protein (4ANK). In the method, groups of residues are assigned to foldons and these foldons are used to map the conformational space of the protein onto a set of discrete macrobasins. The free energies of the individual macrobasins are then calculated, informing practical kinetic analysis. Two simple assumptions about the universality of the rate for downhill transitions between macrobasins and the natural local connectivity between macrobasins lead to a scheme for predicting overall folding and unfolding rates, generating chevron plots under varying thermodynamic conditions, and inferring dominant kinetic folding pathways. To illustrate the approach, free energies of macrobasins were calculated from biased simulations of a non-additive structure-based model using two structurally motivated foldon definitions at the full and half ankyrin repeat resolutions. The calculated chevrons have features consistent with those measured in stopped flow chemical denaturation experiments. The dominant inferred folding pathway has an "inside-out", nucleation-propagation like character.

A multiple perspective modeling and simulation approach for renewable energy policy evaluation

NASA Astrophysics Data System (ADS)

Alyamani, Talal M.

Environmental issues and reliance on fossil fuel sources, including coal, oil, and natural gas, are the two most common energy issues that are currently faced by the United States (U.S.). Incorporation of renewable energy sources, a non-economical option in electricity generation compared to conventional sources that burn fossil fuels, single handedly promises a viable solution for both of these issues. Several energy policies have concordantly been suggested to reduce the financial burden of adopting renewable energy technologies and make such technologies competitive with conventional sources throughout the U.S. This study presents a modeling and analysis approach for comprehensive evaluation of renewable energy policies with respect to their benefits to various related stakeholders--customers, utilities, governmental and environmental agencies--where the debilitating impacts, advantages, and disadvantages of such policies can be assessed and quantified at the state level. In this work, a novel simulation framework is presented to help policymakers promptly assess and evaluate policies from different perspectives of its stakeholders. The proposed framework is composed of four modules: 1) a database that collates the economic, operational, and environmental data; 2) elucidation of policy, which devises the policy for the simulation model; 3) a preliminary analysis, which makes predictions for consumption, supply, and prices; and 4) a simulation model. After the validity of the proposed framework is demonstrated, a series of planned Florida and Texas renewable energy policies are implemented into the presented framework as case studies. Two solar and one energy efficiency programs are selected as part of the Florida case study. A utility rebate and federal tax credit programs are selected as part of the Texas case study. The results obtained from the simulation and conclusions drawn on the assessment of current energy policies are presented with respect to the

Simulation-Based Valuation of Transactive Energy Systems

DOE PAGES

Huang, Qiuhua; McDermott, Tom; Tang, Yingying; ...

2018-05-18

Transactive Energy (TE) has been recognized as a promising technique for integrating responsive loads and distributed energy resources as well as advancing grid modernization. To help the industry better understand the value of TE and compare different TE schemes in a systematic and transparent manner, a comprehensive simulation-based TE valuation method is developed. The method has the following salient features: 1) it formally defines the valuation scenarios, use cases, baseline and valuation metrics; 2) an open-source simulation platform for transactive energy systems has been developed by integrating transmission, distribution and building simulators, and plugin TE and non-TE agents through themore » Framework for Network Co-Simulation (FNCS); 3) transparency and flexibility of the valuation is enhanced through separation of simulation and valuation, base valuation metrics and final valuation metrics. In conclusion, a valuation example based on the Smart Grid Interoperability Panel (SGIP) Use Case 1 is provided to demonstrate the developed TE simulation program and the valuation method.« less

Simulation-Based Valuation of Transactive Energy Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Qiuhua; McDermott, Tom; Tang, Yingying

Transactive Energy (TE) has been recognized as a promising technique for integrating responsive loads and distributed energy resources as well as advancing grid modernization. To help the industry better understand the value of TE and compare different TE schemes in a systematic and transparent manner, a comprehensive simulation-based TE valuation method is developed. The method has the following salient features: 1) it formally defines the valuation scenarios, use cases, baseline and valuation metrics; 2) an open-source simulation platform for transactive energy systems has been developed by integrating transmission, distribution and building simulators, and plugin TE and non-TE agents through themore » Framework for Network Co-Simulation (FNCS); 3) transparency and flexibility of the valuation is enhanced through separation of simulation and valuation, base valuation metrics and final valuation metrics. In conclusion, a valuation example based on the Smart Grid Interoperability Panel (SGIP) Use Case 1 is provided to demonstrate the developed TE simulation program and the valuation method.« less

The Energy-Environment Simulator as a Classroom Aid.

ERIC Educational Resources Information Center

Sell, Nancy J.; Van Koevering, Thomas E.

1981-01-01

Energy-Environment Simulators, provided by the U.S. Department of Energy, can be used to help individuals experience the effects of unbridled energy consumption for the next century on a national or worldwide scale. The simulator described is a specially designed analog computer which models the real-world energy situation. (MP)

Contribution to solving the energy crisis - Simulating the prospects for low cost energy through silicon solar cells

NASA Technical Reports Server (NTRS)

Kran, A.

1978-01-01

PECAN (Photovoltaic Energy Conversion Analysis) is a highly interactive decision analysis and support system. It simulates the prospects for widespread use of solar cells for the generation of electrical power. PECAN consists of a set of integrated APL functions for evaluating the potential of terrestrial photovoltaics. Specifically, the system is a deterministic simulator, which translates present and future manufacturing technology into economic and financial terms, using the production unit concept. It guides solar cell development in three areas: tactical decision making, strategic planning, and the formulation of alternative options.

SIMWEST - A simulation model for wind energy storage systems

NASA Technical Reports Server (NTRS)

Edsinger, R. W.; Warren, A. W.; Gordon, L. H.; Chang, G. C.

1978-01-01

This paper describes a comprehensive and efficient computer program for the modeling of wind energy systems with storage. The level of detail of SIMWEST (SImulation Model for Wind Energy STorage) is consistent with evaluating the economic feasibility as well as the general performance of wind energy systems with energy storage options. The software package consists of two basic programs and a library of system, environmental, and control components. The first program is a precompiler which allows the library components to be put together in building block form. The second program performs the technoeconomic system analysis with the required input/output, and the integration of system dynamics. An example of the application of the SIMWEST program to a current 100 kW wind energy storage system is given.

Simulation on a car interior aerodynamic noise control based on statistical energy analysis

NASA Astrophysics Data System (ADS)

Chen, Xin; Wang, Dengfeng; Ma, Zhengdong

2012-09-01

How to simulate interior aerodynamic noise accurately is an important question of a car interior noise reduction. The unsteady aerodynamic pressure on body surfaces is proved to be the key effect factor of car interior aerodynamic noise control in high frequency on high speed. In this paper, a detail statistical energy analysis (SEA) model is built. And the vibra-acoustic power inputs are loaded on the model for the valid result of car interior noise analysis. The model is the solid foundation for further optimization on car interior noise control. After the most sensitive subsystems for the power contribution to car interior noise are pointed by SEA comprehensive analysis, the sound pressure level of car interior aerodynamic noise can be reduced by improving their sound and damping characteristics. The further vehicle testing results show that it is available to improve the interior acoustic performance by using detailed SEA model, which comprised by more than 80 subsystems, with the unsteady aerodynamic pressure calculation on body surfaces and the materials improvement of sound/damping properties. It is able to acquire more than 2 dB reduction on the central frequency in the spectrum over 800 Hz. The proposed optimization method can be looked as a reference of car interior aerodynamic noise control by the detail SEA model integrated unsteady computational fluid dynamics (CFD) and sensitivity analysis of acoustic contribution.

Environment, power, and society. [stressing energy language and energy analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Odum, H.T.

Studies of the energetics of ecological systems suggest general means for applying basic laws of energy and matter to the complex systems of nature and man. In this book, energy language is used to consider the pressing problem of survival in our time--the partnership of man in nature. An effort is made to show that energy analysis can help answer many of the questions of economics, law, and religion. Models for the analysis of a system are made by recognizing major divisions whose causal relationships are indicated by the pathways of interchange of energy and work. Then simulation allows themore » model's performance to be tested against the performance of the real system. Ideal energy flows are illustrated with ecological systems and then applied to all kinds of situations from very small biochemical processes to the large overall systems of man and the biosphere. Energy diagraming is included to consider the great problems of power, pollution, population, food, and war. This account also attempts to introduce ecology through the energy language.« less

Thermal dynamic simulation of wall for building energy efficiency under varied climate environment

NASA Astrophysics Data System (ADS)

Wang, Xuejin; Zhang, Yujin; Hong, Jing

2017-08-01

Aiming at different kind of walls in five cities of different zoning for thermal design, using thermal instantaneous response factors method, the author develops software to calculation air conditioning cooling load temperature, thermal response factors, and periodic response factors. On the basis of the data, the author gives the net work analysis about the influence of dynamic thermal of wall on air-conditioning load and thermal environment in building of different zoning for thermal design regional, and put forward the strategy how to design thermal insulation and heat preservation wall base on dynamic thermal characteristic of wall under different zoning for thermal design regional. And then provide the theory basis and the technical references for the further study on the heat preservation with the insulation are in the service of energy saving wall design. All-year thermal dynamic load simulating and energy consumption analysis for new energy-saving building is very important in building environment. This software will provide the referable scientific foundation for all-year new thermal dynamic load simulation, energy consumption analysis, building environment systems control, carrying through farther research on thermal particularity and general particularity evaluation for new energy -saving walls building. Based on which, we will not only expediently design system of building energy, but also analyze building energy consumption and carry through scientific energy management. The study will provide the referable scientific foundation for carrying through farther research on thermal particularity and general particularity evaluation for new energy saving walls building.

Predicting RNA Duplex Dimerization Free-Energy Changes upon Mutations Using Molecular Dynamics Simulations.

PubMed

Sakuraba, Shun; Asai, Kiyoshi; Kameda, Tomoshi

2015-11-05

The dimerization free energies of RNA-RNA duplexes are fundamental values that represent the structural stability of RNA complexes. We report a comparative analysis of RNA-RNA duplex dimerization free-energy changes upon mutations, estimated from a molecular dynamics simulation and experiments. A linear regression for nine pairs of double-stranded RNA sequences, six base pairs each, yielded a mean absolute deviation of 0.55 kcal/mol and an R(2) value of 0.97, indicating quantitative agreement between simulations and experimental data. The observed accuracy indicates that the molecular dynamics simulation with the current molecular force field is capable of estimating the thermodynamic properties of RNA molecules.

Turbulence flight director analysis and preliminary simulation

NASA Technical Reports Server (NTRS)

Johnson, D. E.; Klein, R. E.

1974-01-01

A control column and trottle flight director display system is synthesized for use during flight through severe turbulence. The column system is designed to minimize airspeed excursions without overdriving attitude. The throttle system is designed to augment the airspeed regulation and provide an indication of the trim thrust required for any desired flight path angle. Together they form an energy management system to provide harmonious display indications of current aircraft motions and required corrective action, minimize gust upset tendencies, minimize unsafe aircraft excursions, and maintain satisfactory ride qualities. A preliminary fixed-base piloted simulation verified the analysis and provided a shakedown for a more sophisticated moving-base simulation to be accomplished next. This preliminary simulation utilized a flight scenario concept combining piloting tasks, random turbulence, and discrete gusts to create a high but realistic pilot workload conducive to pilot error and potential upset. The turbulence director (energy management) system significantly reduced pilot workload and minimized unsafe aircraft excursions.

Free-energy analysis of the electron-density fluctuation in the quantum-mechanical/molecular-mechanical simulation combined with the theory of energy representation.

PubMed

Matubayasi, Nobuyuki; Takahashi, Hideaki

2012-01-28

The relationship is investigated for QM/MM (quantum-mechanical/molecular-mechanical) systems between the fluctuations of the electronic state of the QM subsystem and of the solvation effect due to the QM-MM interaction. The free-energy change due to the electron-density fluctuation around its average is highlighted, and is evaluated through an approximate functional formulated in terms of distribution functions of the many-body coupling (pairwise non-additive) part of the QM-MM interaction energy. A set of QM/MM simulations are conducted in MM water solvent for QM water solute in ambient and supercritical conditions and for QM glycine solute in the neutral and zwitterionic forms. The variation of the electronic distortion energy of the QM solute in the course of QM/MM simulation is then shown to be compensated by the corresponding variation of the free energy of solvation. The solvation free energy conditioned by the electronic distortion energy is further analyzed with its components. It is found that the many-body contribution is essentially equal between the free energy and the average sum of solute-solvent interaction energy. © 2012 American Institute of Physics

Fluid Flow Simulation and Energetic Analysis of Anomalocarididae Locomotion

NASA Astrophysics Data System (ADS)

Mikel-Stites, Maxwell; Staples, Anne

2014-11-01

While an abundance of animal locomotion simulations have been performed modeling the motions of living arthropods and aquatic animals, little quantitative simulation and reconstruction of gait parameters has been done to model the locomotion of extinct animals, many of which bear little physical resemblance to their modern descendants. To that end, this project seeks to analyze potential swimming patterns used by the anomalocaridid family, (specifically Anomalocaris canadensis, a Cambrian Era aquatic predator), and determine the most probable modes of movement. This will serve to either verify or cast into question the current assumed movement patterns and properties of these animals and create a bridge between similar flexible-bodied swimmers and their robotic counterparts. This will be accomplished by particle-based fluid flow simulations of the flow around the fins of the animal, as well as an energy analysis of a variety of sample gaits. The energy analysis will then be compared to the extant information regarding speed/energy use curves in an attempt to determine which modes of swimming were most energy efficient for a given range of speeds. These results will provide a better understanding of how these long-extinct animals moved, possibly allowing an improved understanding of their behavioral patterns, and may also lead to a novel potential platform for bio-inspired underwater autonomous vehicles (UAVs).

Simulation based analysis of laser beam brazing

NASA Astrophysics Data System (ADS)

Dobler, Michael; Wiethop, Philipp; Schmid, Daniel; Schmidt, Michael

2016-03-01

Laser beam brazing is a well-established joining technology in car body manufacturing with main applications in the joining of divided tailgates and the joining of roof and side panels. A key advantage of laser brazed joints is the seam's visual quality which satisfies highest requirements. However, the laser beam brazing process is very complex and process dynamics are only partially understood. In order to gain deeper knowledge of the laser beam brazing process, to determine optimal process parameters and to test process variants, a transient three-dimensional simulation model of laser beam brazing is developed. This model takes into account energy input, heat transfer as well as fluid and wetting dynamics that lead to the formation of the brazing seam. A validation of the simulation model is performed by metallographic analysis and thermocouple measurements for different parameter sets of the brazing process. These results show that the multi-physical simulation model not only can be used to gain insight into the laser brazing process but also offers the possibility of process optimization in industrial applications. The model's capabilities in determining optimal process parameters are exemplarily shown for the laser power. Small deviations in the energy input can affect the brazing results significantly. Therefore, the simulation model is used to analyze the effect of the lateral laser beam position on the energy input and the resulting brazing seam.

Effective Energy Simulation and Optimal Design of Side-lit Buildings with Venetian Blinds

NASA Astrophysics Data System (ADS)

Cheng, Tian

Venetian blinds are popularly used in buildings to control the amount of incoming daylight for improving visual comfort and reducing heat gains in air-conditioning systems. Studies have shown that the proper design and operation of window systems could result in significant energy savings in both lighting and cooling. However, there is no convenient computer tool that allows effective and efficient optimization of the envelope of side-lit buildings with blinds now. Three computer tools, Adeline, DOE2 and EnergyPlus widely used for the above-mentioned purpose have been experimentally examined in this study. Results indicate that the two former tools give unacceptable accuracy due to unrealistic assumptions adopted while the last one may generate large errors in certain conditions. Moreover, current computer tools have to conduct hourly energy simulations, which are not necessary for life-cycle energy analysis and optimal design, to provide annual cooling loads. This is not computationally efficient, particularly not suitable for optimal designing a building at initial stage because the impacts of many design variations and optional features have to be evaluated. A methodology is therefore developed for efficient and effective thermal and daylighting simulations and optimal design of buildings with blinds. Based on geometric optics and radiosity method, a mathematical model is developed to reasonably simulate the daylighting behaviors of venetian blinds. Indoor illuminance at any reference point can be directly and efficiently computed. They have been validated with both experiments and simulations with Radiance. Validation results show that indoor illuminances computed by the new models agree well with the measured data, and the accuracy provided by them is equivalent to that of Radiance. The computational efficiency of the new models is much higher than that of Radiance as well as EnergyPlus. Two new methods are developed for the thermal simulation of buildings. A

Simulation Studies on Energy Harvesting Characterisitcs and Storage Analysis Through Microcantilever Vibration

NASA Astrophysics Data System (ADS)

Solleti, Ravi Teja; Harikrishna, Kyatham; Velmurugan, V.

Vibrations can be a good source of energy and can be harvested and utilized by simple design and fabrication using the MEMS technology. Energy harvesting provides unending sources of energy for low-power electronics devices where the use of batteries is not feasible. Piezoelectric energy harvesters are widely considered because of their compact design, compatibility to MEMS devices and ability to respond to a wide range of frequencies freely available in the environment. In this project, a rectangular model for cantilever-based piezoelectric energy harvester is proposed with different designs like two layer, two layer with proof mass, four layer and four layer with proof mass designed with dimensions as 50μm×50μm×1μm for each layer using COMSOL Multiphysics 5.0. Simulation results were obtained using silicon as substrate, aluminium as electrodes and PZT-5H and ZnO as piezoelectric materials and the respective stress and voltages were obtained by applying a force acting on foot, train, roller coaster and a general value of 10N/m2 on top of the cantilever. The effects of varying geometrical dimensions of the device were also investigated.

Coarse-grained versus atomistic simulations: realistic interaction free energies for real proteins.

PubMed

May, Ali; Pool, René; van Dijk, Erik; Bijlard, Jochem; Abeln, Sanne; Heringa, Jaap; Feenstra, K Anton

2014-02-01

To assess whether two proteins will interact under physiological conditions, information on the interaction free energy is needed. Statistical learning techniques and docking methods for predicting protein-protein interactions cannot quantitatively estimate binding free energies. Full atomistic molecular simulation methods do have this potential, but are completely unfeasible for large-scale applications in terms of computational cost required. Here we investigate whether applying coarse-grained (CG) molecular dynamics simulations is a viable alternative for complexes of known structure. We calculate the free energy barrier with respect to the bound state based on molecular dynamics simulations using both a full atomistic and a CG force field for the TCR-pMHC complex and the MP1-p14 scaffolding complex. We find that the free energy barriers from the CG simulations are of similar accuracy as those from the full atomistic ones, while achieving a speedup of >500-fold. We also observe that extensive sampling is extremely important to obtain accurate free energy barriers, which is only within reach for the CG models. Finally, we show that the CG model preserves biological relevance of the interactions: (i) we observe a strong correlation between evolutionary likelihood of mutations and the impact on the free energy barrier with respect to the bound state; and (ii) we confirm the dominant role of the interface core in these interactions. Therefore, our results suggest that CG molecular simulations can realistically be used for the accurate prediction of protein-protein interaction strength. The python analysis framework and data files are available for download at http://www.ibi.vu.nl/downloads/bioinformatics-2013-btt675.tgz.

Radiation and ionization energy loss simulation for the GDH sum rule experiment in Hall-A at Jefferson Lab

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Xin -Hu; Ye, Yun -Xiu; Chen, Jian -Ping

2015-07-17

The radiation and ionization energy loss are presented for single arm Monte Carlo simulation for the GDH sum rule experiment in Hall-A at Jefferson Lab. Radiation and ionization energy loss are discussed formore » $$^{12}C$$ elastic scattering simulation. The relative momentum ratio $$\\frac{\\Delta p}{p}$$ and $$^{12}C$$ elastic cross section are compared without and with radiation energy loss and a reasonable shape is obtained by the simulation. The total energy loss distribution is obtained, showing a Landau shape for $$^{12}C$$ elastic scattering. This simulation work will give good support for radiation correction analysis of the GDH sum rule experiment.« less

Energy dynamics in a simulation of LAPD turbulence

NASA Astrophysics Data System (ADS)

Friedman, Brett

2012-10-01

It is often assumed that linear instabilities maintain turbulence in plasmas and some fluids, but this is not always the case. It is well known that many fluids display subcritical turbulence at a Reynolds number well below the threashold of linear instability. Certain plasma models such as drift waves in a sheared slab also exhibit subcritical turbulence [1]. In other instances such as drift-ballooning turbulence in tokamak edge plasmas, linear instabilities exist in a system, but they become subdominant to more robust nonlinear mechanisms that sustain a turbulent state [2, 3]. In our simulation of LAPD turbulence, which was previously analyzed in [4], we diagnose the results using an energy dynamics analysis [5]. This allows us to track energy input into turbulent fluctuations and energy dissipation out of them. We also track conservative energy transfer between different energy types (e.g. from potential to kinetic energy) and between different Fourier waves of the system. The result is that a nonlinear instability drives and maintains the turbulence in the steady state saturated phase of the simulation. While a linear restistive drift wave instability resides in the system, the nonlinear drift wave instability dominates when the fluctuation amplitude becomes large enough. The nonlinear instability is identified by its energy growth rate spectrum, which varies significantly from the linear growth rate spectrum. The main differences are the presence of positive growth rates when k|| = 0 and negative growth rates for nonzero k||, which is opposite that of the linear growth rate spectrum.[4pt] [1] B. D. Scott, Phys. Rev. Lett., 65, 3289 (1990).[0pt] [2] A. Zeiler et al, Phys. Plasmas, 3, 2951 (1996).[0pt] [3] B. D. Scott, Phys. Plasmas, 12, 062314 (2005).[0pt] [4] P. Popovich et al, Phys. Plasmas, 17, 122312 (2010).[0pt] [5] [physics.plasm-ph].

Water Energy Simulation Toolset

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Thuy; Jeffers, Robert

The Water-Energy Simulation Toolset (WEST) is an interactive simulation model that helps visualize impacts of different stakeholders on water quantity and quality of a watershed. The case study is applied for the Snake River Basin with the fictional name Cutthroat River Basin. There are four groups of stakeholders of interest: hydropower, agriculture, flood control, and environmental protection. Currently, the quality component depicts nitrogen-nitrate contaminant. Users can easily interact with the model by changing certain inputs (climate change, fertilizer inputs, etc.) to observe the change over the entire system. Users can also change certain parameters to test their management policy.

Simulation and visualization of energy-related occupant behavior in office buildings

DOE PAGES

Chen, Yixing; Liang, Xin; Hong, Tianzhen; ...

2017-03-15

In current building performance simulation programs, occupant presence and interactions with building systems are over-simplified and less indicative of real world scenarios, contributing to the discrepancies between simulated and actual energy use in buildings. Simulation results are normally presented using various types of charts. However, using those charts, it is difficult to visualize and communicate the importance of occupants’ behavior to building energy performance. This study introduced a new approach to simulating and visualizing energy-related occupant behavior in office buildings. First, the Occupancy Simulator was used to simulate the occupant presence and movement and generate occupant schedules for each spacemore » as well as for each occupant. Then an occupant behavior functional mockup unit (obFMU) was used to model occupant behavior and analyze their impact on building energy use through co-simulation with EnergyPlus. Finally, an agent-based model built upon AnyLogic was applied to visualize the simulation results of the occupant movement and interactions with building systems, as well as the related energy performance. A case study using a small office building in Miami, FL was presented to demonstrate the process and application of the Occupancy Simulator, the obFMU and EnergyPlus, and the AnyLogic module in simulation and visualization of energy-related occupant behaviors in office buildings. Furthermore, the presented approach provides a new detailed and visual way for policy makers, architects, engineers and building operators to better understand occupant energy behavior and their impact on energy use in buildings, which can improve the design and operation of low energy buildings.« less

Simulation and visualization of energy-related occupant behavior in office buildings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Yixing; Liang, Xin; Hong, Tianzhen

In current building performance simulation programs, occupant presence and interactions with building systems are over-simplified and less indicative of real world scenarios, contributing to the discrepancies between simulated and actual energy use in buildings. Simulation results are normally presented using various types of charts. However, using those charts, it is difficult to visualize and communicate the importance of occupants’ behavior to building energy performance. This study introduced a new approach to simulating and visualizing energy-related occupant behavior in office buildings. First, the Occupancy Simulator was used to simulate the occupant presence and movement and generate occupant schedules for each spacemore » as well as for each occupant. Then an occupant behavior functional mockup unit (obFMU) was used to model occupant behavior and analyze their impact on building energy use through co-simulation with EnergyPlus. Finally, an agent-based model built upon AnyLogic was applied to visualize the simulation results of the occupant movement and interactions with building systems, as well as the related energy performance. A case study using a small office building in Miami, FL was presented to demonstrate the process and application of the Occupancy Simulator, the obFMU and EnergyPlus, and the AnyLogic module in simulation and visualization of energy-related occupant behaviors in office buildings. Furthermore, the presented approach provides a new detailed and visual way for policy makers, architects, engineers and building operators to better understand occupant energy behavior and their impact on energy use in buildings, which can improve the design and operation of low energy buildings.« less

Building Energy Simulation Test for Existing Homes (BESTEST-EX) (Presentation)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Judkoff, R.; Neymark, J.; Polly, B.

2011-12-01

This presentation discusses the goals of NREL Analysis Accuracy R&D; BESTEST-EX goals; what BESTEST-EX is; how it works; 'Building Physics' cases; 'Building Physics' reference results; 'utility bill calibration' cases; limitations and potential future work. Goals of NREL Analysis Accuracy R&D are: (1) Provide industry with the tools and technical information needed to improve the accuracy and consistency of analysis methods; (2) Reduce the risks associated with purchasing, financing, and selling energy efficiency upgrades; and (3) Enhance software and input collection methods considering impacts on accuracy, cost, and time of energy assessments. BESTEST-EX Goals are: (1) Test software predictions of retrofitmore » energy savings in existing homes; (2) Ensure building physics calculations and utility bill calibration procedures perform up to a minimum standard; and (3) Quantify impact of uncertainties in input audit data and occupant behavior. BESTEST-EX is a repeatable procedure that tests how well audit software predictions compare to the current state of the art in building energy simulation. There is no direct truth standard. However, reference software have been subjected to validation testing, including comparisons with empirical data.« less

The new program OPAL for molecular dynamics simulations and energy refinements of biological macromolecules.

PubMed

Luginbühl, P; Güntert, P; Billeter, M; Wüthrich, K

1996-09-01

A new program for molecular dynamics (MD) simulation and energy refinement of biological macromolecules, OPAL, is introduced. Combined with the supporting program TRAJEC for the analysis of MD trajectories, OPAL affords high efficiency and flexibility for work with different force fields, and offers a user-friendly interface and extensive trajectory analysis capabilities. Salient features are computational speeds of up to 1.5 GFlops on vector supercomputers such as the NEC SX-3, ellipsoidal boundaries to reduce the system size for studies in explicit solvents, and natural treatment of the hydrostatic pressure. Practical applications of OPAL are illustrated with MD simulations of pure water, energy minimization of the NMR structure of the mixed disulfide of a mutant E. coli glutaredoxin with glutathione in different solvent models, and MD simulations of a small protein, pheromone Er-2, using either instantaneous or time-averaged NMR restraints, or no restraints.

Suitability of Synthetic Driving Profiles from Traffic Micro-Simulation for Real-World Energy Analysis: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hou, Yunfei; Wood, Eric; Burton, Evan

A shift towards increased levels of driving automation is generally expected to result in improved safety and traffic congestion outcomes. However, little empirical data exists to estimate the impact that automated driving could have on energy consumption and greenhouse gas emissions. In the absence of empirical data on differences between drive cycles from present day vehicles (primarily operated by humans) and future vehicles (partially or fully operated by computers) one approach is to model both situations over identical traffic conditions. Such an exercise requires traffic micro-simulation to not only accurately model vehicle operation under high levels of automation, but alsomore » (and potentially more challenging) vehicle operation under present day human drivers. This work seeks to quantify the ability of a commercial traffic micro-simulation program to accurately model real-world drive cycles in vehicles operated primarily by humans in terms of driving speed, acceleration, and simulated fuel economy. Synthetic profiles from models of freeway and arterial facilities near Atlanta, Georgia, are compared to empirical data collected from real-world drivers on the same facilities. Empirical and synthetic drive cycles are then simulated in a powertrain efficiency model to enable comparison on the basis of fuel economy. Synthetic profiles from traffic micro-simulation were found to exhibit low levels of transient behavior relative to the empirical data. Even with these differences, the synthetic and empirical data in this study agree well in terms of driving speed and simulated fuel economy. The differences in transient behavior between simulated and empirical data suggest that larger stochastic contributions in traffic micro-simulation (relative to those present in the traffic micro-simulation tool used in this study) are required to fully capture the arbitrary elements of human driving. Interestingly, the lack of stochastic contributions from models of human

Efficient Analysis of Simulations of the Sun's Magnetic Field

NASA Astrophysics Data System (ADS)

Scarborough, C. W.; Martínez-Sykora, J.

2014-12-01

Dynamics in the solar atmosphere, including solar flares, coronal mass ejections, micro-flares and different types of jets, are powered by the evolution of the sun's intense magnetic field. 3D Radiative Magnetohydrodnamics (MHD) computer simulations have furthered our understanding of the processes involved: When non aligned magnetic field lines reconnect, the alteration of the magnetic topology causes stored magnetic energy to be converted into thermal and kinetic energy. Detailed analysis of this evolution entails tracing magnetic field lines, an operation which is not time-efficient on a single processor. By utilizing a graphics card (GPU) to trace lines in parallel, conducting such analysis is made feasible. We applied our GPU implementation to the most advanced 3D Radiative-MHD simulations (Bifrost, Gudicksen et al. 2011) of the solar atmosphere in order to better understand the evolution of the modeled field lines.

Liberian macroeconomy and simulation of sectoral energy demand: 1981-2000

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hill, L.J.

1984-06-01

The primary purpose of this report is to document the results of a research effort on end-use, sector energy demand in Liberia, West Africa over the 1981-2000 time horizon. The research was undertaken as one component of a much broader integrated energy assessment of Liberia. Other components of the assessment, however, focused on current energy supply and consumption together with future energy supply options for Liberia. This particular report is devoted exclusively to a discussion of Liberian energy demand. The methodology utilized to simulate Liberian sectoral energy demand over the period 1981-2000 involved the recursive interaction of a macroeconomic modelmore » and individual, econometrically-estimated sectoral demand equations. That is, given the projections for gross output in the Liberian economy from the macroeconomic model, sectoral energy demand was simulated. The individual energy demand equations were estimated on the basis of economic variables that are theorized to influence energy consumption in the respective sectors (e.g., price, output). The primary conclusion drawn from the analysis is that, besides being sensitive to changes in international economic activity, the demand for energy in Liberia over the 1981 to 2000 horizon is highly sensitive to internal production of its two primary exports: iron ore and rubber. More specifically, as characterized in the four scenarios, future growth in Liberian energy demand is contingent on the output of three companies: the Liberian American Swedish Mining Company, the Bong Mining Company, and the Firestone Rubber Company. Therefore, expansion of Liberia's energy supply capacity in the future should proceed cautiously. 16 references, 6 figures, 15 tables.« less

QM/MM free energy simulations: recent progress and challenges

PubMed Central

Lu, Xiya; Fang, Dong; Ito, Shingo; Okamoto, Yuko; Ovchinnikov, Victor

2016-01-01

Due to the higher computational cost relative to pure molecular mechanical (MM) simulations, hybrid quantum mechanical/molecular mechanical (QM/MM) free energy simulations particularly require a careful consideration of balancing computational cost and accuracy. Here we review several recent developments in free energy methods most relevant to QM/MM simulations and discuss several topics motivated by these developments using simple but informative examples that involve processes in water. For chemical reactions, we highlight the value of invoking enhanced sampling technique (e.g., replica-exchange) in umbrella sampling calculations and the value of including collective environmental variables (e.g., hydration level) in metadynamics simulations; we also illustrate the sensitivity of string calculations, especially free energy along the path, to various parameters in the computation. Alchemical free energy simulations with a specific thermodynamic cycle are used to probe the effect of including the first solvation shell into the QM region when computing solvation free energies. For cases where high-level QM/MM potential functions are needed, we analyze two different approaches: the QM/MM-MFEP method of Yang and co-workers and perturbative correction to low-level QM/MM free energy results. For the examples analyzed here, both approaches seem productive although care needs to be exercised when analyzing the perturbative corrections. PMID:27563170

Protein free energy landscapes from long equilibrium simulations

NASA Astrophysics Data System (ADS)

Piana-Agostinetti, Stefano

Many computational techniques based on molecular dynamics (MD) simulation can be used to generate data to aid in the construction of protein free energy landscapes with atomistic detail. Unbiased, long, equilibrium MD simulations--although computationally very expensive--are particularly appealing, as they can provide direct kinetic and thermodynamic information on the transitions between the states that populate a protein free energy surface. It can be challenging to know how to analyze and interpret even results generated by this direct technique, however. I will discuss approaches we have employed, using equilibrium MD simulation data, to obtain descriptions of the free energy landscapes of proteins ranging in size from tens to thousands of amino acids.

Simulation of radiation energy release in air showers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glaser, Christian; Erdmann, Martin; Hörandel, Jörg R.

2016-09-01

A simulation study of the energy released by extensive air showers in the form of MHz radiation is performed using the CoREAS simulation code. We develop an efficient method to extract this radiation energy from air-shower simulations. We determine the longitudinal profile of the radiation energy release and compare it to the longitudinal profile of the energy deposit by the electromagnetic component of the air shower. We find that the radiation energy corrected for the geometric dependence of the geomagnetic emission scales quadratically with the energy in the electromagnetic component of the air shower with a second-order dependence on themore » atmospheric density at the position of the maximum shower development X {sub max}. In a measurement where X {sub max} is not accessible, this second order dependence can be approximated using the zenith angle of the incoming direction of the air shower with only a minor loss in accuracy. Our method results in an intrinsic uncertainty of 4% in the determination of the energy in the electromagnetic air-shower component, which is well below current experimental uncertainties.« less

Computer Simulation in Predicting Biochemical Processes and Energy Balance at WWTPs

NASA Astrophysics Data System (ADS)

Drewnowski, Jakub; Zaborowska, Ewa; Hernandez De Vega, Carmen

2018-02-01

Nowadays, the use of mathematical models and computer simulation allow analysis of many different technological solutions as well as testing various scenarios in a short time and at low financial budget in order to simulate the scenario under typical conditions for the real system and help to find the best solution in design or operation process. The aim of the study was to evaluate different concepts of biochemical processes and energy balance modelling using a simulation platform GPS-x and a comprehensive model Mantis2. The paper presents the example of calibration and validation processes in the biological reactor as well as scenarios showing an influence of operational parameters on the WWTP energy balance. The results of batch tests and full-scale campaign obtained in the former work were used to predict biochemical and operational parameters in a newly developed plant model. The model was extended with sludge treatment devices, including anaerobic digester. Primary sludge removal efficiency was found as a significant factor determining biogas production and further renewable energy production in cogeneration. Water and wastewater utilities, which run and control WWTP, are interested in optimizing the process in order to save environment, their budget and decrease the pollutant emissions to water and air. In this context, computer simulation can be the easiest and very useful tool to improve the efficiency without interfering in the actual process performance.

Simulating the energy performance of holographic glazings

NASA Astrophysics Data System (ADS)

Papamichael, K.; Beltran, L.; Furler, Reto; Lee, E. S.; Selkowitz, Steven E.; Rubin, Michael

1994-09-01

The light diffraction properties of holographic diffractive structures present an opportunity to improve the daylight performance in side-lit office spaces by redirecting and reflecting sunlight off the ceiling, providing adequate daylight illumination up to 30 ft (9.14 m) from the window wall. Prior studies of prototypical holographic glazings, installed above conventional `view' windows, have shown increased daylight levels over a deeper perimeter area than clear glass, for selected sun positions. In this study, we report on the simulation of the energy performance of prototypical holographic glazings assuming a commercial office building in the inland Los Angeles climate. The simulation of the energy performance involved determination of both luminous and thermal performance. Since the optical complexity of holographic glazings prevented the use of conventional algorithms for the simulation of their luminous performance, we used a newly developed method that combines experimentally determined directional workplane illuminance coefficients with computer-based analytical routines to determine a comprehensive set of daylight factors for many sun positions. These daylight factors were then used within the DOE-2.1D energy simulation program to determine hourly daylight and energy performance over the course of an entire year for four window orientations. Since the prototypical holographic diffractive structures considered in this study were applied on single pane clear glass, we also simulated the performance of hypothetical glazings, assuming the daylight performance of the prototype holographic glazings and the thermal performance of double-pane and low-e glazings. Finally, we addressed various design and implementation issues towards potential performance improvement.

Protecting High Energy Barriers: A New Equation to Regulate Boost Energy in Accelerated Molecular Dynamics Simulations.

PubMed

Sinko, William; de Oliveira, César Augusto F; Pierce, Levi C T; McCammon, J Andrew

2012-01-10

Molecular dynamics (MD) is one of the most common tools in computational chemistry. Recently, our group has employed accelerated molecular dynamics (aMD) to improve the conformational sampling over conventional molecular dynamics techniques. In the original aMD implementation, sampling is greatly improved by raising energy wells below a predefined energy level. Recently, our group presented an alternative aMD implementation where simulations are accelerated by lowering energy barriers of the potential energy surface. When coupled with thermodynamic integration simulations, this implementation showed very promising results. However, when applied to large systems, such as proteins, the simulation tends to be biased to high energy regions of the potential landscape. The reason for this behavior lies in the boost equation used since the highest energy barriers are dramatically more affected than the lower ones. To address this issue, in this work, we present a new boost equation that prevents oversampling of unfavorable high energy conformational states. The new boost potential provides not only better recovery of statistics throughout the simulation but also enhanced sampling of statistically relevant regions in explicit solvent MD simulations.

Refined lateral energy correction functions for the KASCADE-Grande experiment based on Geant4 simulations

NASA Astrophysics Data System (ADS)

Gherghel-Lascu, A.; Apel, W. D.; Arteaga-Velázquez, J. C.; Bekk, K.; Bertaina, M.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Cantoni, E.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.; Engler, J.; Fuchs, B.; Fuhrmann, D.; Gils, H. J.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Huber, D.; Huege, T.; Kampert, K.-H.; Kang, D.; Klages, H. O.; Link, K.; Łuczak, P.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.; Oehlschläger, J.; Ostapchenko, S.; Palmieri, N.; Petcu, M.; Pierog, T.; Rebel, H.; Roth, M.; Schieler, H.; Schoo, S.; Schröder, F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Ulrich, H.; Weindl, A.; Wochele, J.; Zabierowski, J.

2015-02-01

In previous studies of KASCADE-Grande data, a Monte Carlo simulation code based on the GEANT3 program has been developed to describe the energy deposited by EAS particles in the detector stations. In an attempt to decrease the simulation time and ensure compatibility with the geometry description in standard KASCADE-Grande analysis software, several structural elements have been neglected in the implementation of the Grande station geometry. To improve the agreement between experimental and simulated data, a more accurate simulation of the response of the KASCADE-Grande detector is necessary. A new simulation code has been developed based on the GEANT4 program, including a realistic geometry of the detector station with structural elements that have not been considered in previous studies. The new code is used to study the influence of a realistic detector geometry on the energy deposited in the Grande detector stations by particles from EAS events simulated by CORSIKA. Lateral Energy Correction Functions are determined and compared with previous results based on GEANT3.

The Measures Contribution Researches on Renewable Energy Accommodation Based on Production Simulation

NASA Astrophysics Data System (ADS)

Zhe, MI; Jinfang, Zhang; Jun, Liu

2018-06-01

This paper presents the impacts of load, source and grid factors on renewable energy accommodation in the northern region of China. Renewable energy curtailment reasons and key measures to improve accommodations are also discussed. The production simulation method is utilized to analysis renewable energy accommodation and the Shapely value method is introduced to calculate the accommodation contribution rate of different factors. The result shows that the amount of renewable energy accommodation is 389 TWh in northern region of China by the year 2020. The contribution rate of load, source and grid factors to renewable energy accommodation are 39%, 35.8% and 25.1%, respectively.

Testing simulation and structural models with applications to energy demand

NASA Astrophysics Data System (ADS)

Wolff, Hendrik

2007-12-01

This dissertation deals with energy demand and consists of two parts. Part one proposes a unified econometric framework for modeling energy demand and examples illustrate the benefits of the technique by estimating the elasticity of substitution between energy and capital. Part two assesses the energy conservation policy of Daylight Saving Time and empirically tests the performance of electricity simulation. In particular, the chapter "Imposing Monotonicity and Curvature on Flexible Functional Forms" proposes an estimator for inference using structural models derived from economic theory. This is motivated by the fact that in many areas of economic analysis theory restricts the shape as well as other characteristics of functions used to represent economic constructs. Specific contributions are (a) to increase the computational speed and tractability of imposing regularity conditions, (b) to provide regularity preserving point estimates, (c) to avoid biases existent in previous applications, and (d) to illustrate the benefits of our approach via numerical simulation results. The chapter "Can We Close the Gap between the Empirical Model and Economic Theory" discusses the more fundamental question of whether the imposition of a particular theory to a dataset is justified. I propose a hypothesis test to examine whether the estimated empirical model is consistent with the assumed economic theory. Although the proposed methodology could be applied to a wide set of economic models, this is particularly relevant for estimating policy parameters that affect energy markets. This is demonstrated by estimating the Slutsky matrix and the elasticity of substitution between energy and capital, which are crucial parameters used in computable general equilibrium models analyzing energy demand and the impacts of environmental regulations. Using the Berndt and Wood dataset, I find that capital and energy are complements and that the data are significantly consistent with duality

Dynamic extension of the Simulation Problem Analysis Kernel (SPANK)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sowell, E.F.; Buhl, W.F.

1988-07-15

The Simulation Problem Analysis Kernel (SPANK) is an object-oriented simulation environment for general simulation purposes. Among its unique features is use of the directed graph as the primary data structure, rather than the matrix. This allows straightforward use of graph algorithms for matching variables and equations, and reducing the problem graph for efficient numerical solution. The original prototype implementation demonstrated the principles for systems of algebraic equations, allowing simulation of steady-state, nonlinear systems (Sowell 1986). This paper describes how the same principles can be extended to include dynamic objects, allowing simulation of general dynamic systems. The theory is developed andmore » an implementation is described. An example is taken from the field of building energy system simulation. 2 refs., 9 figs.« less

Rise time of proton cut-off energy in 2D and 3D PIC simulations

NASA Astrophysics Data System (ADS)

Babaei, J.; Gizzi, L. A.; Londrillo, P.; Mirzanejad, S.; Rovelli, T.; Sinigardi, S.; Turchetti, G.

2017-04-01

The Target Normal Sheath Acceleration regime for proton acceleration by laser pulses is experimentally consolidated and fairly well understood. However, uncertainties remain in the analysis of particle-in-cell simulation results. The energy spectrum is exponential with a cut-off, but the maximum energy depends on the simulation time, following different laws in two and three dimensional (2D, 3D) PIC simulations so that the determination of an asymptotic value has some arbitrariness. We propose two empirical laws for the rise time of the cut-off energy in 2D and 3D PIC simulations, suggested by a model in which the proton acceleration is due to a surface charge distribution on the target rear side. The kinetic energy of the protons that we obtain follows two distinct laws, which appear to be nicely satisfied by PIC simulations, for a model target given by a uniform foil plus a contaminant layer that is hydrogen-rich. The laws depend on two parameters: the scaling time, at which the energy starts to rise, and the asymptotic cut-off energy. The values of the cut-off energy, obtained by fitting 2D and 3D simulations for the same target and laser pulse configuration, are comparable. This suggests that parametric scans can be performed with 2D simulations since 3D ones are computationally very expensive, delegating their role only to a correspondence check. In this paper, the simulations are carried out with the PIC code ALaDyn by changing the target thickness L and the incidence angle α, with a fixed a0 = 3. A monotonic dependence, on L for normal incidence and on α for fixed L, is found, as in the experimental results for high temporal contrast pulses.

Computer simulated building energy consumption for verification of energy conservation measures in network facilities

NASA Technical Reports Server (NTRS)

Plankey, B.

1981-01-01

A computer program called ECPVER (Energy Consumption Program - Verification) was developed to simulate all energy loads for any number of buildings. The program computes simulated daily, monthly, and yearly energy consumption which can be compared with actual meter readings for the same time period. Such comparison can lead to validation of the model under a variety of conditions, which allows it to be used to predict future energy saving due to energy conservation measures. Predicted energy saving can then be compared with actual saving to verify the effectiveness of those energy conservation changes. This verification procedure is planned to be an important advancement in the Deep Space Network Energy Project, which seeks to reduce energy cost and consumption at all DSN Deep Space Stations.

Energy consumption analysis of the Venus Deep Space Station (DSS-13)

NASA Technical Reports Server (NTRS)

Hayes, N. V.

1983-01-01

This report continues the energy consumption analysis and verification study of the tracking stations of the Goldstone Deep Space Communications Complex, and presents an audit of the Venus Deep Space Station (DSS 13). Due to the non-continuous radioastronomy research and development operations at the station, estimations of energy usage were employed in the energy consumption simulation of both the 9-meter and 26-meter antenna buildings. A 17.9% decrease in station energy consumption was experienced over the 1979-1981 years under study. A comparison of the ECP computer simulations and the station's main watt-hour meter readings showed good agreement.

Analysis of laser energy characteristics of laser guided weapons based on the hardware-in-the-loop simulation system

NASA Astrophysics Data System (ADS)

Zhu, Yawen; Cui, Xiaohong; Wang, Qianqian; Tong, Qiujie; Cui, Xutai; Li, Chenyu; Zhang, Le; Peng, Zhong

2016-11-01

The hardware-in-the-loop simulation system, which provides a precise, controllable and repeatable test conditions, is an important part of the development of the semi-active laser (SAL) guided weapons. In this paper, laser energy chain characteristics were studied, which provides a theoretical foundation for the SAL guidance technology and the hardware-in-the-loop simulation system. Firstly, a simplified equation was proposed to adjust the radar equation according to the principles of the hardware-in-the-loop simulation system. Secondly, a theoretical model and calculation method were given about the energy chain characteristics based on the hardware-in-the-loop simulation system. We then studied the reflection characteristics of target and the distance between the missile and target with major factors such as the weather factors. Finally, the accuracy of modeling was verified by experiment as the values measured experimentally generally follow the theoretical results from the model. And experimental results revealed that ratio of attenuation of the laser energy exhibited a non-linear change vs. pulse number, which were in accord with the actual condition.

Free energies from dynamic weighted histogram analysis using unbiased Markov state model.

PubMed

Rosta, Edina; Hummer, Gerhard

2015-01-13

The weighted histogram analysis method (WHAM) is widely used to obtain accurate free energies from biased molecular simulations. However, WHAM free energies can exhibit significant errors if some of the biasing windows are not fully equilibrated. To account for the lack of full equilibration, we develop the dynamic histogram analysis method (DHAM). DHAM uses a global Markov state model to obtain the free energy along the reaction coordinate. A maximum likelihood estimate of the Markov transition matrix is constructed by joint unbiasing of the transition counts from multiple umbrella-sampling simulations along discretized reaction coordinates. The free energy profile is the stationary distribution of the resulting Markov matrix. For this matrix, we derive an explicit approximation that does not require the usual iterative solution of WHAM. We apply DHAM to model systems, a chemical reaction in water treated using quantum-mechanics/molecular-mechanics (QM/MM) simulations, and the Na(+) ion passage through the membrane-embedded ion channel GLIC. We find that DHAM gives accurate free energies even in cases where WHAM fails. In addition, DHAM provides kinetic information, which we here use to assess the extent of convergence in each of the simulation windows. DHAM may also prove useful in the construction of Markov state models from biased simulations in phase-space regions with otherwise low population.

Building Energy Consumption Pattern Analysis of Detached Housing for the Policy Decision Simulator

NASA Astrophysics Data System (ADS)

Lim, Jiyoun; Lee, Seung-Eon

2018-03-01

The Korean government announced its plan to raise the previous reduction goal of greenhouse gas emission from buildings by 26.9% until 2020 on July 2015. Therefore, policies regarding efficiency in the building energy are implemented fast, but the level of building owners and market understanding is low in general, and the government service system which supports decision making for implementing low-energy buildings has not been provided yet. The purpose of this study is to present the design direction for establishing user customized building energy database to perform a role to provide autonomous ecosystem of low-energy buildings. In order to reduce energy consumption in buildings, it is necessary to carry out the energy performance analysis based on the characteristics of target building. By analysing about 20-thousand cases of the amount of housing energy consumption in Korea, this study suggested the real energy consumption pattern by building types. Also, the energy performance of a building could be determined by energy consumption, but previous building energy consumption analysis programs required expert knowledge and experience in program usage, so it was difficult for normal building users to use such programs. Therefore, a measure to provide proper default using the level of data which general users with no expert knowledge regarding building energy could enter easily was suggested in this study.

Simulation of Flywheel Energy Storage System Controls

NASA Technical Reports Server (NTRS)

Truong, Long V.; Wolff, Frederick J.; Dravid, Narayan

2001-01-01

This paper presents the progress made in the controller design and operation of a flywheel energy storage system. The switching logic for the converter bridge circuit has been redefined to reduce line current harmonics, even at the highest operating speed of the permanent magnet motor-generator. An electromechanical machine model is utilized to simulate charge and discharge operation of the inertial energy in the flywheel. Controlling the magnitude of phase currents regulates the rate of charge and discharge. The resulting improvements are demonstrated by simulation.

Essential energy space random walks to accelerate molecular dynamics simulations: Convergence improvements via an adaptive-length self-healing strategy

NASA Astrophysics Data System (ADS)

Zheng, Lianqing; Yang, Wei

2008-07-01

Recently, accelerated molecular dynamics (AMD) technique was generalized to realize essential energy space random walks so that further sampling enhancement and effective localized enhanced sampling could be achieved. This method is especially meaningful when essential coordinates of the target events are not priori known; moreover, the energy space metadynamics method was also introduced so that biasing free energy functions can be robustly generated. Despite the promising features of this method, due to the nonequilibrium nature of the metadynamics recursion, it is challenging to rigorously use the data obtained at the recursion stage to perform equilibrium analysis, such as free energy surface mapping; therefore, a large amount of data ought to be wasted. To resolve such problem so as to further improve simulation convergence, as promised in our original paper, we are reporting an alternate approach: the adaptive-length self-healing (ALSH) strategy for AMD simulations; this development is based on a recent self-healing umbrella sampling method. Here, the unit simulation length for each self-healing recursion is increasingly updated based on the Wang-Landau flattening judgment. When the unit simulation length for each update is long enough, all the following unit simulations naturally run into the equilibrium regime. Thereafter, these unit simulations can serve for the dual purposes of recursion and equilibrium analysis. As demonstrated in our model studies, by applying ALSH, both fast recursion and short nonequilibrium data waste can be compromised. As a result, combining all the data obtained from all the unit simulations that are in the equilibrium regime via the weighted histogram analysis method, efficient convergence can be robustly ensured, especially for the purpose of free energy surface mapping.

Energy performance analysis of a detached single-family house to be refurbished

NASA Astrophysics Data System (ADS)

Aleixo, Kevin; Curado, António

2017-07-01

This study was developed with the purpose of analyzing the reinforcement of the energy performance in a detached single-family house to be refurbished, using this building as a case-study for simulation and experimental analysis. The building is located in Viana do Castelo, a city in the northwest of Portugal nearby the Atlantic Ocean. The developed study was carried out in order to characterize the thermal performance of the house, using simulation analysis in a dynamic regime. The energy consumption study was developed in permanent regime analysis, using simulation tools. At the end, the study aimed to propose and define the best retrofitting solutions, both passive and active, and to improve the energy performance of the building. The outcomes of the study provided the importance of passive retrofitting solutions on thermal comfort and energy performance. The use of a set of thermal solutions, as the insulation of the roof, walls and the windows, it is possible to achieve a global gain of 0, 63 °C and to reduce energy consumption in 61, 46 [kWh/m2.year]. The study of the building in a simplified thermal regime, according to the Portuguese energy efficiency regulation, allowed the determination of the energy efficiency class of the house and retrofitting solutions proposed. The initial energy performance class of the building is C. With the application of a passive set of solutions, it's possible to improve the energy performance to a class B. With the implementation of some active solutions, it is possible to reach an energy class A +.

Theoretical modeling, simulation and experimental study of hybrid piezoelectric and electromagnetic energy harvester

NASA Astrophysics Data System (ADS)

Li, Ping; Gao, Shiqiao; Cong, Binglong

2018-03-01

In this paper, performances of vibration energy harvester combined piezoelectric (PE) and electromagnetic (EM) mechanism are studied by theoretical analysis, simulation and experimental test. For the designed harvester, electromechanical coupling modeling is established, and expressions of vibration response, output voltage, current and power are derived. Then, performances of the harvester are simulated and tested; moreover, the power charging rechargeable battery is realized through designed energy storage circuit. By the results, it's found that compared with piezoelectric-only and electromagnetic-only energy harvester, the hybrid energy harvester can enhance the output power and harvesting efficiency; furthermore, at the harmonic excitation, output power of harvester linearly increases with acceleration amplitude increasing; while it enhances with acceleration spectral density increasing at the random excitation. In addition, the bigger coupling strength, the bigger output power is, and there is the optimal load resistance to make the harvester output the maximal power.

Free Energy Landscape of Protein-Protein Encounter Resulting from Brownian Dynamics Simulations of Barnase:Barstar.

PubMed

Spaar, Alexander; Helms, Volkhard

2005-07-01

Over the past years Brownian dynamics (BD) simulations have been proven to be a suitable tool for the analysis of protein-protein association. The computed rates and relative trends for protein mutants and different ionic strength are generally in good agreement with experimental results, e.g. see ref 1. By design, BD simulations correspond to an intensive sampling over energetically favorable states, rather than to a systematic sampling over all possible states which is feasible only at rather low resolution. On the example of barnase and barstar, a well characterized model system of electrostatically steered diffusional encounter, we report here the computation of the 6-dimensional free energy landscape for the encounter process of two proteins by a novel, careful analysis of the trajectories from BD simulations. The aim of these studies was the clarification of the encounter state. Along the trajectories, the individual positions and orientations of one protein (relative to the other) are recorded and stored in so-called occupancy maps. Since the number of simulated trajectories is sufficiently high, these occupancy maps can be interpreted as a probability distribution which allows the calculation of the entropy landscape by the use of a locally defined entropy function. Additionally, the configuration dependent electrostatic and desolvation energies are recorded in separate maps. The free energy landscape of protein-protein encounter is finally obtained by summing the energy and entropy contributions. In the free energy profile along the reaction path, which is defined as the path along the minima in the free energy landscape, a minimum shows up suggesting this to be used as the definition of the encounter state. This minimum describes a state of reduced diffusion velocity where the electrostatic attraction is compensated by the repulsion due to the unfavorable desolvation of the charged residues and the entropy loss due to the increasing restriction of the

Exploring the Energy Landscapes of Protein Folding Simulations with Bayesian Computation

PubMed Central

Burkoff, Nikolas S.; Várnai, Csilla; Wells, Stephen A.; Wild, David L.

2012-01-01

Nested sampling is a Bayesian sampling technique developed to explore probability distributions localized in an exponentially small area of the parameter space. The algorithm provides both posterior samples and an estimate of the evidence (marginal likelihood) of the model. The nested sampling algorithm also provides an efficient way to calculate free energies and the expectation value of thermodynamic observables at any temperature, through a simple post processing of the output. Previous applications of the algorithm have yielded large efficiency gains over other sampling techniques, including parallel tempering. In this article, we describe a parallel implementation of the nested sampling algorithm and its application to the problem of protein folding in a Gō-like force field of empirical potentials that were designed to stabilize secondary structure elements in room-temperature simulations. We demonstrate the method by conducting folding simulations on a number of small proteins that are commonly used for testing protein-folding procedures. A topological analysis of the posterior samples is performed to produce energy landscape charts, which give a high-level description of the potential energy surface for the protein folding simulations. These charts provide qualitative insights into both the folding process and the nature of the model and force field used. PMID:22385859

A hadron-nucleus collision event generator for simulations at intermediate energies

NASA Astrophysics Data System (ADS)

Ackerstaff, K.; Bisplinghoff, J.; Bollmann, R.; Cloth, P.; Diehl, O.; Dohrmann, F.; Drüke, V.; Eisenhardt, S.; Engelhardt, H. P.; Ernst, J.; Eversheim, P. D.; Filges, D.; Fritz, S.; Gasthuber, M.; Gebel, R.; Greiff, J.; Gross, A.; Gross-Hardt, R.; Hinterberger, F.; Jahn, R.; Lahr, U.; Langkau, R.; Lippert, G.; Maschuw, R.; Mayer-Kuckuk, T.; Mertler, G.; Metsch, B.; Mosel, F.; Paetz gen. Schieck, H.; Petry, H. R.; Prasuhn, D.; von Przewoski, B.; Rohdjeß, H.; Rosendaal, D.; Roß, U.; von Rossen, P.; Scheid, H.; Schirm, N.; Schulz-Rojahn, M.; Schwandt, F.; Scobel, W.; Sterzenbach, G.; Theis, D.; Weber, J.; Wellinghausen, A.; Wiedmann, W.; Woller, K.; Ziegler, R.; EDDA-Collaboration

2002-10-01

Several available codes for hadronic event generation and shower simulation are discussed and their predictions are compared to experimental data in order to obtain a satisfactory description of hadronic processes in Monte Carlo studies of detector systems for medium energy experiments. The most reasonable description is found for the intra-nuclear-cascade (INC) model of Bertini which employs microscopic description of the INC, taking into account elastic and inelastic pion-nucleon and nucleon-nucleon scattering. The isobar model of Sternheimer and Lindenbaum is used to simulate the inelastic elementary collisions inside the nucleus via formation and decay of the Δ33-resonance which, however, limits the model at higher energies. To overcome this limitation, the INC model has been extended by using the resonance model of the HADRIN code, considering all resonances in elementary collisions contributing more than 2% to the total cross-section up to kinetic energies of 5 GeV. In addition, angular distributions based on phase shift analysis are used for elastic nucleon-nucleon as well as elastic and charge exchange pion-nucleon scattering. Also kaons and antinucleons can be treated as projectiles. Good agreement with experimental data is found predominantly for lower projectile energies, i.e. in the regime of the Bertini code. The original as well as the extended Bertini model have been implemented as shower codes into the high energy detector simulation package GEANT-3.14, allowing now its use also in full Monte Carlo studies of detector systems at intermediate energies. The GEANT-3.14 here have been used mainly for its powerful geometry and analysing packages due to the complex EDDA detector system.

Energy Analysis Research | Energy Analysis | NREL

Science.gov Websites

innovation through integration. Illustration of NREL energy analysis research, including impact systems analysis integrates all aspects of our capability set to develop future energy system scenarios evaluate and understand the impact of markets, policies, and financing on technology uptake and the impact

EnergyPlus Run Time Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, Tianzhen; Buhl, Fred; Haves, Philip

2008-09-20

EnergyPlus is a new generation building performance simulation program offering many new modeling capabilities and more accurate performance calculations integrating building components in sub-hourly time steps. However, EnergyPlus runs much slower than the current generation simulation programs. This has become a major barrier to its widespread adoption by the industry. This paper analyzed EnergyPlus run time from comprehensive perspectives to identify key issues and challenges of speeding up EnergyPlus: studying the historical trends of EnergyPlus run time based on the advancement of computers and code improvements to EnergyPlus, comparing EnergyPlus with DOE-2 to understand and quantify the run time differences,more » identifying key simulation settings and model features that have significant impacts on run time, and performing code profiling to identify which EnergyPlus subroutines consume the most amount of run time. This paper provides recommendations to improve EnergyPlus run time from the modeler?s perspective and adequate computing platforms. Suggestions of software code and architecture changes to improve EnergyPlus run time based on the code profiling results are also discussed.« less

Free energy analysis of cell spreading.

PubMed

McEvoy, Eóin; Deshpande, Vikram S; McGarry, Patrick

2017-10-01

In this study we present a steady-state adaptation of the thermodynamically motivated stress fiber (SF) model of Vigliotti et al. (2015). We implement this steady-state formulation in a non-local finite element setting where we also consider global conservation of the total number of cytoskeletal proteins within the cell, global conservation of the number of binding integrins on the cell membrane, and adhesion limiting ligand density on the substrate surface. We present a number of simulations of cell spreading in which we consider a limited subset of the possible deformed spread-states assumed by the cell in order to examine the hypothesis that free energy minimization drives the process of cell spreading. Simulations suggest that cell spreading can be viewed as a competition between (i) decreasing cytoskeletal free energy due to strain induced assembly of cytoskeletal proteins into contractile SFs, and (ii) increasing elastic free energy due to stretching of the mechanically passive components of the cell. The computed minimum free energy spread area is shown to be lower for a cell on a compliant substrate than on a rigid substrate. Furthermore, a low substrate ligand density is found to limit cell spreading. The predicted dependence of cell spread area on substrate stiffness and ligand density is in agreement with the experiments of Engler et al. (2003). We also simulate the experiments of Théry et al. (2006), whereby initially circular cells deform and adhere to "V-shaped" and "Y-shaped" ligand patches. Analysis of a number of different spread states reveals that deformed configurations with the lowest free energy exhibit a SF distribution that corresponds to experimental observations, i.e. a high concentration of highly aligned SFs occurs along free edges, with lower SF concentrations in the interior of the cell. In summary, the results of this study suggest that cell spreading is driven by free energy minimization based on a competition between decreasing

Energy Savings Analysis of the Proposed NYStretch-Energy Code 2018

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Bing; Zhang, Jian; Chen, Yan

This study was conducted by the Pacific Northwest National Laboratory (PNNL) in support of the stretch energy code development led by the New York State Energy Research and Development Authority (NYSERDA). In 2017 NYSERDA developed its 2016 Stretch Code Supplement to the 2016 New York State Energy Conservation Construction Code (hereinafter referred to as “NYStretch-Energy”). NYStretch-Energy is intended as a model energy code for statewide voluntary adoption that anticipates other code advancements culminating in the goal of a statewide Net Zero Energy Code by 2028. Since then, NYSERDA continues to develop the NYStretch-Energy Code 2018 edition. To support the effort,more » PNNL conducted energy simulation analysis to quantify the energy savings of proposed commercial provisions of the NYStretch-Energy Code (2018) in New York. The focus of this project is the 20% improvement over existing commercial model energy codes. A key requirement of the proposed stretch code is that it be ‘adoptable’ as an energy code, meaning that it must align with current code scope and limitations, and primarily impact building components that are currently regulated by local building departments. It is largely limited to prescriptive measures, which are what most building departments and design projects are most familiar with. This report describes a set of energy-efficiency measures (EEMs) that demonstrate 20% energy savings over ANSI/ASHRAE/IES Standard 90.1-2013 (ASHRAE 2013) across a broad range of commercial building types and all three climate zones in New York. In collaboration with New Building Institute, the EEMs were developed from national model codes and standards, high-performance building codes and standards, regional energy codes, and measures being proposed as part of the on-going code development process. PNNL analyzed these measures using whole building energy models for selected prototype commercial buildings and multifamily buildings representing buildings

Simulation of electricity demand in a remote island for optimal planning of a hybrid renewable energy system

NASA Astrophysics Data System (ADS)

Koskinas, Aristotelis; Zacharopoulou, Eleni; Pouliasis, George; Engonopoulos, Ioannis; Mavroyeoryos, Konstantinos; Deligiannis, Ilias; Karakatsanis, Georgios; Dimitriadis, Panayiotis; Iliopoulou, Theano; Koutsoyiannis, Demetris; Tyralis, Hristos

2017-04-01

We simulate the electrical energy demand in the remote island of Astypalaia. To this end we first obtain information regarding the local socioeconomic conditions and energy demand. Secondly, the available hourly demand data are analysed at various time scales (hourly, weekly, daily, seasonal). The cross-correlations between the electrical energy demand and the mean daily temperature as well as other climatic variables for the same time period are computed. Also, we investigate the cross-correlation between those climatic variables and other variables related to renewable energy resources from numerous observations around the globe in order to assess the impact of each one to a hybrid renewable energy system. An exploratory data analysis including all variables is performed with the purpose to find hidden relationships. Finally, the demand is simulated considering all the periodicities found in the analysis. The simulation time series will be used in the development of a framework for planning of a hybrid renewable energy system in Astypalaia. Acknowledgement: This research is conducted within the frame of the undergraduate course "Stochastic Methods in Water Resources" of the National Technical University of Athens (NTUA). The School of Civil Engineering of NTUA provided moral support for the participation of the students in the Assembly.

Efficient and Robust Optimization for Building Energy Simulation.

PubMed

Pourarian, Shokouh; Kearsley, Anthony; Wen, Jin; Pertzborn, Amanda

2016-06-15

Efficiently, robustly and accurately solving large sets of structured, non-linear algebraic and differential equations is one of the most computationally expensive steps in the dynamic simulation of building energy systems. Here, the efficiency, robustness and accuracy of two commonly employed solution methods are compared. The comparison is conducted using the HVACSIM+ software package, a component based building system simulation tool. The HVACSIM+ software presently employs Powell's Hybrid method to solve systems of nonlinear algebraic equations that model the dynamics of energy states and interactions within buildings. It is shown here that the Powell's method does not always converge to a solution. Since a myriad of other numerical methods are available, the question arises as to which method is most appropriate for building energy simulation. This paper finds considerable computational benefits result from replacing the Powell's Hybrid method solver in HVACSIM+ with a solver more appropriate for the challenges particular to numerical simulations of buildings. Evidence is provided that a variant of the Levenberg-Marquardt solver has superior accuracy and robustness compared to the Powell's Hybrid method presently used in HVACSIM+.

Computational Analysis on Performance of Thermal Energy Storage (TES) Diffuser

NASA Astrophysics Data System (ADS)

Adib, M. A. H. M.; Adnan, F.; Ismail, A. R.; Kardigama, K.; Salaam, H. A.; Ahmad, Z.; Johari, N. H.; Anuar, Z.; Azmi, N. S. N.

2012-09-01

Application of thermal energy storage (TES) system reduces cost and energy consumption. The performance of the overall operation is affected by diffuser design. In this study, computational analysis is used to determine the thermocline thickness. Three dimensional simulations with different tank height-to-diameter ratio (HD), diffuser opening and the effect of difference number of diffuser holes are investigated. Medium HD tanks simulations with double ring octagonal diffuser show good thermocline behavior and clear distinction between warm and cold water. The result show, the best performance of thermocline thickness during 50% time charging occur in medium tank with height-to-diameter ratio of 4.0 and double ring octagonal diffuser with 48 holes (9mm opening ~ 60%) acceptable compared to diffuser with 6mm ~ 40% and 12mm ~ 80% opening. The conclusion is computational analysis method are very useful in the study on performance of thermal energy storage (TES).

Analysis of vibrational-translational energy transfer using the direct simulation Monte Carlo method

NASA Technical Reports Server (NTRS)

Boyd, Iain D.

1991-01-01

A new model is proposed for energy transfer between the vibrational and translational modes for use in the direct simulation Monte Carlo method (DSMC). The model modifies the Landau-Teller theory for a harmonic oscillator and the rate transition is related to an experimental correlation for the vibrational relaxation time. Assessment of the model is made with respect to three different computations: relaxation in a heat bath, a one-dimensional shock wave, and hypersonic flow over a two-dimensional wedge. These studies verify that the model achieves detailed balance, and excellent agreement with experimental data is obtained in the shock wave calculation. The wedge flow computation reveals that the usual phenomenological method for simulating vibrational nonequilibrium in the DSMC technique predicts much higher vibrational temperatures in the wake region.

Performance of Geant4 in simulating semiconductor particle detector response in the energy range below 1 MeV

NASA Astrophysics Data System (ADS)

Soti, G.; Wauters, F.; Breitenfeldt, M.; Finlay, P.; Kraev, I. S.; Knecht, A.; Porobić, T.; Zákoucký, D.; Severijns, N.

2013-11-01

Geant4 simulations play a crucial role in the analysis and interpretation of experiments providing low energy precision tests of the Standard Model. This paper focuses on the accuracy of the description of the electron processes in the energy range between 100 and 1000 keV. The effect of the different simulation parameters and multiple scattering models on the backscattering coefficients is investigated. Simulations of the response of HPGe and passivated implanted planar Si detectors to β particles are compared to experimental results. An overall good agreement is found between Geant4 simulations and experimental data.

Visualizing Energy on Target: Molecular Dynamics Simulations

DTIC Science & Technology

2017-12-01

ARL-TR-8234 ● DEC 2017 US Army Research Laboratory Visualizing Energy on Target: Molecular Dynamics Simulations by DeCarlos E...return it to the originator. ARL-TR-8234● DEC 2017 US Army Research Laboratory Visualizing Energy on Target: Molecular Dynamics...REPORT TYPE Technical Report 3. DATES COVERED (From - To) 1 October 2015–30 September 2016 4. TITLE AND SUBTITLE Visualizing Energy on Target

Crisis on Mars: Classroom Energy Simulation.

ERIC Educational Resources Information Center

Pribble, Donald A.

1979-01-01

Described in this article is an energy conservation simulation game in which students participate in a space mission to Mars. Activities such as decision making, valuing, and problem solving occur during the game. (SA)

Model and particle-in-cell simulation of ion energy distribution in collisionless sheath

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Zhuwen, E-mail: zzwwdxy@gznc.edu.cn; Key Laboratory of Photoelectron Materials Design and Simulation in Guizhou Province, Guiyang 550018; Scientific Research Innovation Team in Plasma and Functional Thin Film Materials in Guizhou Province, Guiyang 550018

2015-06-15

In this paper, we propose a self-consistent theoretical model, which is described by the ion energy distributions (IEDs) in collisionless sheaths, and the analytical results for different combined dc/radio frequency (rf) capacitive coupled plasma discharge cases, including sheath voltage errors analysis, are compared with the results of numerical simulations using a one-dimensional plane-parallel particle-in-cell (PIC) simulation. The IEDs in collisionless sheaths are performed on combination of dc/rf voltage sources electrodes discharge using argon as the process gas. The incident ions on the grounded electrode are separated, according to their different radio frequencies, and dc voltages on a separated electrode, themore » IEDs, and widths of energy in sheath and the plasma sheath thickness are discussed. The IEDs, the IED widths, and sheath voltages by the theoretical model are investigated and show good agreement with PIC simulations.« less

Simulation based energy-resource efficient manufacturing integrated with in-process virtual management

NASA Astrophysics Data System (ADS)

Katchasuwanmanee, Kanet; Cheng, Kai; Bateman, Richard

2016-09-01

As energy efficiency is one of the key essentials towards sustainability, the development of an energy-resource efficient manufacturing system is among the great challenges facing the current industry. Meanwhile, the availability of advanced technological innovation has created more complex manufacturing systems that involve a large variety of processes and machines serving different functions. To extend the limited knowledge on energy-efficient scheduling, the research presented in this paper attempts to model the production schedule at an operation process by considering the balance of energy consumption reduction in production, production work flow (productivity) and quality. An innovative systematic approach to manufacturing energy-resource efficiency is proposed with the virtual simulation as a predictive modelling enabler, which provides real-time manufacturing monitoring, virtual displays and decision-makings and consequentially an analytical and multidimensional correlation analysis on interdependent relationships among energy consumption, work flow and quality errors. The regression analysis results demonstrate positive relationships between the work flow and quality errors and the work flow and energy consumption. When production scheduling is controlled through optimization of work flow, quality errors and overall energy consumption, the energy-resource efficiency can be achieved in the production. Together, this proposed multidimensional modelling and analysis approach provides optimal conditions for the production scheduling at the manufacturing system by taking account of production quality, energy consumption and resource efficiency, which can lead to the key competitive advantages and sustainability of the system operations in the industry.

Closing loop base pairs in RNA loop-loop complexes: structural behavior, interaction energy and solvation analysis through molecular dynamics simulations.

PubMed

Golebiowski, Jérôme; Antonczak, Serge; Fernandez-Carmona, Juan; Condom, Roger; Cabrol-Bass, Daniel

2004-12-01

Nanosecond molecular dynamics using the Ewald summation method have been performed to elucidate the structural and energetic role of the closing base pair in loop-loop RNA duplexes neutralized by Mg2+ counterions in aqueous phases. Mismatches GA, CU and Watson-Crick GC base pairs have been considered for closing the loop of an RNA in complementary interaction with HIV-1 TAR. The simulations reveal that the mismatch GA base, mediated by a water molecule, leads to a complex that presents the best compromise between flexibility and energetic contributions. The mismatch CU base pair, in spite of the presence of an inserted water molecule, is too short to achieve a tight interaction at the closing-loop junction and seems to force TAR to reorganize upon binding. An energetic analysis has allowed us to quantify the strength of the interactions of the closing and the loop-loop pairs throughout the simulations. Although the water-mediated GA closing base pair presents an interaction energy similar to that found on fully geometry-optimized structure, the water-mediated CU closing base pair energy interaction reaches less than half the optimal value.

Analysis of the interrelationship of energy, economy, and environment: A model of a sustainable energy future for Korea

NASA Astrophysics Data System (ADS)

Boo, Kyung-Jin

The primary purpose of this dissertation is to provide the groundwork for a sustainable energy future in Korea. For this purpose, a conceptual framework of sustainable energy development was developed to provide a deeper understanding of interrelationships between energy, the economy, and the environment (E 3). Based on this theoretical work, an empirical simulation model was developed to investigate the ways in which E3 interact. This dissertation attempts to develop a unified concept of sustainable energy development by surveying multiple efforts to integrate various definitions of sustainability. Sustainable energy development should be built on the basis of three principles: ecological carrying capacity, economic efficiency, and socio-political equity. Ecological carrying capacity delineates the earth's resource constraints as well as its ability to assimilate wastes. Socio-political equity implies an equitable distribution of the benefits and costs of energy consumption and an equitable distribution of environmental burdens. Economic efficiency dictates efficient allocation of scarce resources. The simulation model is composed of three modules: an energy module, an environmental module and an economic module. Because the model is grounded on economic structural behaviorism, the dynamic nature of the current economy is effectively depicted and simulated through manipulating exogenous policy variables. This macro-economic model is used to simulate six major policy intervention scenarios. Major findings from these policy simulations were: (1) carbon taxes are the most effective means of reducing air-pollutant emissions; (2) sustainable energy development can be achieved through reinvestment of carbon taxes into energy efficiency and renewable energy programs; and (3) carbon taxes would increase a nation's welfare if reinvested in relevant areas. The policy simulation model, because it is based on neoclassical economics, has limitations such that it cannot fully

Exploring the energy landscapes of protein folding simulations with Bayesian computation.

PubMed

Burkoff, Nikolas S; Várnai, Csilla; Wells, Stephen A; Wild, David L

2012-02-22

Nested sampling is a Bayesian sampling technique developed to explore probability distributions localized in an exponentially small area of the parameter space. The algorithm provides both posterior samples and an estimate of the evidence (marginal likelihood) of the model. The nested sampling algorithm also provides an efficient way to calculate free energies and the expectation value of thermodynamic observables at any temperature, through a simple post processing of the output. Previous applications of the algorithm have yielded large efficiency gains over other sampling techniques, including parallel tempering. In this article, we describe a parallel implementation of the nested sampling algorithm and its application to the problem of protein folding in a Gō-like force field of empirical potentials that were designed to stabilize secondary structure elements in room-temperature simulations. We demonstrate the method by conducting folding simulations on a number of small proteins that are commonly used for testing protein-folding procedures. A topological analysis of the posterior samples is performed to produce energy landscape charts, which give a high-level description of the potential energy surface for the protein folding simulations. These charts provide qualitative insights into both the folding process and the nature of the model and force field used. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

High resolution simulations of energy absorption in dynamically loaded cellular structures

NASA Astrophysics Data System (ADS)

Winter, R. E.; Cotton, M.; Harris, E. J.; Eakins, D. E.; McShane, G.

2017-03-01

Cellular materials have potential application as absorbers of energy generated by high velocity impact. CTH, a Sandia National Laboratories Code which allows very severe strains to be simulated, has been used to perform very high resolution simulations showing the dynamic crushing of a series of two-dimensional, stainless steel metal structures with varying architectures. The structures are positioned to provide a cushion between a solid stainless steel flyer plate with velocities ranging from 300 to 900 m/s, and an initially stationary stainless steel target. Each of the alternative architectures under consideration was formed by an array of identical cells each of which had a constant volume and a constant density. The resolution of the simulations was maximised by choosing a configuration in which one-dimensional conditions persisted for the full period over which the specimen densified, a condition which is most readily met by impacting high density specimens at high velocity. It was found that the total plastic flow and, therefore, the irreversible energy dissipated in the fully densified energy absorbing cell, increase (a) as the structure becomes more rodlike and less platelike and (b) as the impact velocity increases. Sequential CTH images of the deformation processes show that the flow of the cell material may be broadly divided into macroscopic flow perpendicular to the compression direction and jetting-type processes (microkinetic flow) which tend to predominate in rod and rodlike configurations and also tend to play an increasing role at increased strain rates. A very simple analysis of a configuration in which a solid flyer impacts a solid target provides a baseline against which to compare and explain features seen in the simulations. The work provides a basis for the development of energy absorbing structures for application in the 200-1000 m/s impact regime.

Energy transfer mechanism and probability analysis of submarine pipe laterally impacted by dropped objects

NASA Astrophysics Data System (ADS)

Liang, Jing; Yu, Jian-xing; Yu, Yang; Lam, W.; Zhao, Yi-yu; Duan, Jing-hui

2016-06-01

Energy transfer ratio is the basic-factor affecting the level of pipe damage during the impact between dropped object and submarine pipe. For the purpose of studying energy transfer and damage mechanism of submarine pipe impacted by dropped objects, series of experiments are designed and carried out. The effective yield strength is deduced to make the quasi-static analysis more reliable, and the normal distribution of energy transfer ratio caused by lateral impact on pipes is presented by statistic analysis of experimental results based on the effective yield strength, which provides experimental and theoretical basis for the risk analysis of submarine pipe system impacted by dropped objects. Failure strains of pipe material are confirmed by comparing experimental results with finite element simulation. In addition, impact contact area and impact time are proved to be the major influence factors of energy transfer by sensitivity analysis of the finite element simulation.

Entry, concentration and market efficiency: A simulation of the PJM energy market

NASA Astrophysics Data System (ADS)

Harvill, Terry

The rapid and substantial expansion of the PJM energy market during 2004 and 2005 provides a unique opportunity to test the theory of market concentration and its effect on market efficiency. With ten years of operational experience, the PJM energy market is uniquely suited to test the theories of market concentration and efficiency in a natural experiment. This research tests the hypothesis that, for a given number of generating units in the industry, system marginal price will be a decreasing function of the number of owners or generators controlling the units (i.e., the industry concentration ratio). Market simulations are utilized to assess price-cost markups in the PJM energy market during three distinct periods of expansion: (1) pre-Commonwealth Edison integration, (2) pre-American Electric Power (AEP), Dayton Power and Light (DPL), Duquesne Light (Duquesne), and Dominion Virginia Power (Dominion) integration, and (3) post-AFT, DPL. Duquesne, and Dominion Integration. The results of the market simulations for the May 1 to August 31 periods for 2003, 2004, and 2005, indicate that the performance of the market improved with the addition of new market participants in 2004 and 2005. The results of the simulation indicate that the load-weighted Lerner index decreased to -3.70 percent in 2005 from 0.92 percent in 2003. Clearly, the addition of Commonwealth Edison in 2004 significantly increased constraints within the PJM energy market and likely impacted the observed prices in PJM during 2004 due to the lack of a significant link to the other PJM market participants. This deficiency was address in 2005 with the addition of American Electric Power. The market simulations also highlight the prevalence of computed negative markups in the simulation results. Many of the off-peak periods in particular are characterized by negative markups where the expected marginal cost exceeds the observed price. Unit commitment constraints are believed to largely account for these

Efficient and Robust Optimization for Building Energy Simulation

PubMed Central

Pourarian, Shokouh; Kearsley, Anthony; Wen, Jin; Pertzborn, Amanda

2016-01-01

Efficiently, robustly and accurately solving large sets of structured, non-linear algebraic and differential equations is one of the most computationally expensive steps in the dynamic simulation of building energy systems. Here, the efficiency, robustness and accuracy of two commonly employed solution methods are compared. The comparison is conducted using the HVACSIM+ software package, a component based building system simulation tool. The HVACSIM+ software presently employs Powell’s Hybrid method to solve systems of nonlinear algebraic equations that model the dynamics of energy states and interactions within buildings. It is shown here that the Powell’s method does not always converge to a solution. Since a myriad of other numerical methods are available, the question arises as to which method is most appropriate for building energy simulation. This paper finds considerable computational benefits result from replacing the Powell’s Hybrid method solver in HVACSIM+ with a solver more appropriate for the challenges particular to numerical simulations of buildings. Evidence is provided that a variant of the Levenberg-Marquardt solver has superior accuracy and robustness compared to the Powell’s Hybrid method presently used in HVACSIM+. PMID:27325907

Simulation for analysis and control of superplastic forming. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zacharia, T.; Aramayo, G.A.; Simunovic, S.

1996-08-01

A joint study was conducted by Oak Ridge National Laboratory (ORNL) and the Pacific Northwest Laboratory (PNL) for the U.S. Department of Energy-Lightweight Materials (DOE-LWM) Program. the purpose of the study was to assess and benchmark the current modeling capabilities with respect to accuracy of predictions and simulation time. Two modeling capabilities with respect to accuracy of predictions and simulation time. Two simulation platforms were considered in this study, which included the LS-DYNA3D code installed on ORNL`s high- performance computers and the finite element code MARC used at PNL. both ORNL and PNL performed superplastic forming (SPF) analysis on amore » standard butter-tray geometry, which was defined by PNL, to better understand the capabilities of the respective models. The specific geometry was selected and formed at PNL, and the experimental results, such as forming time and thickness at specific locations, were provided for comparisons with numerical predictions. Furthermore, comparisons between the ORNL simulation results, using elasto-plastic analysis, and PNL`s results, using rigid-plastic flow analysis, were performed.« less

Simulating the Value of Concentrating Solar Power with Thermal Energy Storage in a Production Cost Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Denholm, P.; Hummon, M.

2012-11-01

Concentrating solar power (CSP) deployed with thermal energy storage (TES) provides a dispatchable source of renewable energy. The value of CSP with TES, as with other potential generation resources, needs to be established using traditional utility planning tools. Production cost models, which simulate the operation of grid, are often used to estimate the operational value of different generation mixes. CSP with TES has historically had limited analysis in commercial production simulations. This document describes the implementation of CSP with TES in a commercial production cost model. It also describes the simulation of grid operations with CSP in a test systemmore » consisting of two balancing areas located primarily in Colorado.« less

Energy Storage Analysis of a Mixed R161/MOF-5 Nanoparticle Nanofluid Based on Molecular Simulations

PubMed Central

Wang, Qiang; Tang, Shengli; Li, Leilei

2018-01-01

The thermal properties of refrigerants can be modified by adding porous nanoparticles into them. Here, molecular simulations, including molecular dynamics and grand canonical Monte Carlo, were employed to study the thermal energy storage properties of an R161/MOF-5 nanofluid. The results show that the thermodynamic energy change of MOF-5 nanoparticles is linear to the temperature. The adsorption heat calculated by grand canonical Monte Carlo is close to that calculated by the Clausius–Clapeyron equation. Additionally, a negative enhancement of the thermal energy storage capacity of the R161/MOF-5 nanofluid is found near the phase transition area. PMID:29783773

Energy Storage Analysis of a Mixed R161/MOF-5 Nanoparticle Nanofluid Based on Molecular Simulations.

PubMed

Wang, Qiang; Tang, Shengli; Li, Leilei

2018-05-20

The thermal properties of refrigerants can be modified by adding porous nanoparticles into them. Here, molecular simulations, including molecular dynamics and grand canonical Monte Carlo, were employed to study the thermal energy storage properties of an R161/MOF-5 nanofluid. The results show that the thermodynamic energy change of MOF-5 nanoparticles is linear to the temperature. The adsorption heat calculated by grand canonical Monte Carlo is close to that calculated by the Clausius⁻Clapeyron equation. Additionally, a negative enhancement of the thermal energy storage capacity of the R161/MOF-5 nanofluid is found near the phase transition area.

Analysis of plasma particle and energy fluxes to material surfaces from tokamak edge turbulence simulations

NASA Astrophysics Data System (ADS)

Umansky, M. V.; Cohen, B. I.; Rognlien, T. D.; Boedo, J. A.; Rudakov, D. L.

2012-10-01

Recent BOUT simulations of edge plasma turbulence in L-mode regime in the boundary region of DIII-D tokamak have demonstrated reasonable match with key edge diagnostics [1]. Order-of-magnitude level agreement has been found in the characteristic amplitude, wavenumber, and frequency of turbulent fluctuations, as compared with experimental data from reciprocating edge Langmuir probe and Beam Emission Spectroscopy systems. Owing to this encouraging agreement, output data from these simulations are analyzed to get insights on physical mechanisms and properties of plasma particle and energy fluxes to material surfaces. Of particular interest is plasma turbulence propagating into, or generated in, the far scrape-off layer region where plasma interacts with material walls. Results of statistical analyses of simulated turbulence plasma transport will be presented and physical implications will be discussed. [4pt] [1] B.I. Cohen et al., APS-DPP 2012

Development of EnergyPlus Utility to Batch Simulate Building Energy Performance on a National Scale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valencia, Jayson F.; Dirks, James A.

2008-08-29

EnergyPlus is a simulation program that requires a large number of details to fully define and model a building. Hundreds or even thousands of lines in a text file are needed to run the EnergyPlus simulation depending on the size of the building. To manually create these files is a time consuming process that would not be practical when trying to create input files for thousands of buildings needed to simulate national building energy performance. To streamline the process needed to create the input files for EnergyPlus, two methods were created to work in conjunction with the National Renewable Energymore » Laboratory (NREL) Preprocessor; this reduced the hundreds of inputs needed to define a building in EnergyPlus to a small set of high-level parameters. The first method uses Java routines to perform all of the preprocessing on a Windows machine while the second method carries out all of the preprocessing on the Linux cluster by using an in-house built utility called Generalized Parametrics (GPARM). A comma delimited (CSV) input file is created to define the high-level parameters for any number of buildings. Each method then takes this CSV file and uses the data entered for each parameter to populate an extensible markup language (XML) file used by the NREL Preprocessor to automatically prepare EnergyPlus input data files (idf) using automatic building routines and macro templates. Using a Linux utility called “make”, the idf files can then be automatically run through the Linux cluster and the desired data from each building can be aggregated into one table to be analyzed. Creating a large number of EnergyPlus input files results in the ability to batch simulate building energy performance and scale the result to national energy consumption estimates.« less

HEAO-1 analysis of Low Energy Detectors (LED)

NASA Technical Reports Server (NTRS)

Nousek, John A.

1992-01-01

The activities at Penn State University are described. During the period Oct. 1990 to Dec. 1991 work on HEAO-1 analysis of the Low Energy Detectors (LED) concentrated on using the improved detector spectral simulation model and fitting diffuse x-ray background spectral data. Spectral fitting results, x-ray point sources, and diffuse x-ray sources are described.

Reasoning about energy in qualitative simulation

NASA Technical Reports Server (NTRS)

Fouche, Pierre; Kuipers, Benjamin J.

1992-01-01

While possible behaviors of a mechanism that are consistent with an incomplete state of knowledge can be predicted through qualitative modeling and simulation, spurious behaviors corresponding to no solution of any ordinary differential equation consistent with the model may be generated. The present method for energy-related reasoning eliminates an important source of spurious behaviors, as demonstrated by its application to a nonlinear, proportional-integral controlled. It is shown that such qualitative properties of such a system as stability and zero-offset control are captured by the simulation.

Simulations of the Fe K α Energy Spectra from Gravitationally Microlensed Quasars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krawczynski, H.; Chartas, G., E-mail: krawcz@wustl.edu

The analysis of the Chandra X-ray observations of the gravitationally lensed quasar RX J1131−1231 revealed the detection of multiple and energy-variable spectral peaks. The spectral variability is thought to result from the microlensing of the Fe K α emission, selectively amplifying the emission from certain regions of the accretion disk with certain effective frequency shifts of the Fe K α line emission. In this paper, we combine detailed simulations of the emission of Fe K α photons from the accretion disk of a Kerr black hole with calculations of the effect of gravitational microlensing on the observed energy spectra. Themore » simulations show that microlensing can indeed produce multiply peaked energy spectra. We explore the dependence of the spectral characteristics on black hole spin, accretion disk inclination, corona height, and microlensing amplification factor and show that the measurements can be used to constrain these parameters. We find that the range of observed spectral peak energies of QSO RX J1131−1231 can only be reproduced for black hole inclinations exceeding 70° and for lamppost corona heights of less than 30 gravitational radii above the black hole. We conclude by emphasizing the scientific potential of studies of the microlensed Fe K α quasar emission and the need for more detailed modeling that explores how the results change for more realistic accretion disk and corona geometries and microlensing magnification patterns. A full analysis should furthermore model the signal-to-noise ratio of the observations and the resulting detection biases.« less

Merging Energy Policy Decision Support, Education, and Communication: The 'World Energy' Simulation Role-Playing Game

NASA Astrophysics Data System (ADS)

Rooney-varga, J. N.; Franck, T.; Jones, A.; Sterman, J.; Sawin, E.

2013-12-01

To meet international goals for climate change mitigation and adaptation, as well as energy access and equity, there is an urgent need to explore and define energy policy paths forward. Despite this need, students, citizens, and decision-makers often hold deeply flawed mental models of the energy and climate systems. Here we describe a simulation role-playing game, World Energy, that provides an immersive learning experience in which participants can create their own path forward for global energy policy and learn about the impact of their policy choices on carbon dioxide emissions, temperature rise, energy supply mix, energy prices, and energy demand. The game puts players in the decision-making roles of advisors to the United Nations Sustainable Energy for All Initiative (drawn from international leaders from industry, governments, intergovernmental organizations, and citizens groups) and, using a state-of-the-art decision-support simulator, asks them to negotiate a plan for global energy policy. We use the En-ROADS (Energy Rapid Overview and Decision Support) simulator, which runs on a laptop computer in <0.1 sec. En-ROADS enables users to specify many factors, including R&D-driven cost reductions in fossil fuel-based, renewable, or carbon-neutral energy technologies; taxes and subsidies for different energy sources; performance standards and energy efficiency; emissions prices; policies to address other greenhouse gas emissions (e.g., methane, nitrous oxide, chlorofluorocarbons, etc.); and assumptions about GDP and population. In World Energy, participants must balance climate change mitigation goals with equity, prices and access to energy, and the political feasibility of policies. Initial results indicate participants gain insights into the dynamics of the energy and climate systems and greater understanding of the potential impacts policies.

NECAP: NASA's Energy-Cost Analysis Program. Part 1: User's manual

NASA Technical Reports Server (NTRS)

Henninger, R. H. (Editor)

1975-01-01

The NECAP is a sophisticated building design and energy analysis tool which has embodied within it all of the latest ASHRAE state-of-the-art techniques for performing thermal load calculation and energy usage predictions. It is a set of six individual computer programs which include: response factor program, data verification program, thermal load analysis program, variable temperature program, system and equipment simulation program, and owning and operating cost program. Each segment of NECAP is described, and instructions are set forth for preparing the required input data and for interpreting the resulting reports.

Hybrid Simulation Modeling to Estimate U.S. Energy Elasticities

NASA Astrophysics Data System (ADS)

Baylin-Stern, Adam C.

This paper demonstrates how an U.S. application of CIMS, a technologically explicit and behaviourally realistic energy-economy simulation model which includes macro-economic feedbacks, can be used to derive estimates of elasticity of substitution (ESUB) and autonomous energy efficiency index (AEEI) parameters. The ability of economies to reduce greenhouse gas emissions depends on the potential for households and industry to decrease overall energy usage, and move from higher to lower emissions fuels. Energy economists commonly refer to ESUB estimates to understand the degree of responsiveness of various sectors of an economy, and use estimates to inform computable general equilibrium models used to study climate policies. Using CIMS, I have generated a set of future, 'pseudo-data' based on a series of simulations in which I vary energy and capital input prices over a wide range. I then used this data set to estimate the parameters for transcendental logarithmic production functions using regression techniques. From the production function parameter estimates, I calculated an array of elasticity of substitution values between input pairs. Additionally, this paper demonstrates how CIMS can be used to calculate price-independent changes in energy-efficiency in the form of the AEEI, by comparing energy consumption between technologically frozen and 'business as usual' simulations. The paper concludes with some ideas for model and methodological improvement, and how these might figure into future work in the estimation of ESUBs from CIMS. Keywords: Elasticity of substitution; hybrid energy-economy model; translog; autonomous energy efficiency index; rebound effect; fuel switching.

Validation of the train energy and dynamics simulator (TEDS).

DOT National Transportation Integrated Search

2015-01-01

FRA has developed Train Energy and Dynamics Simulator (TEDS) based upon a longitudinal train dynamics and operations : simulation model which allows users to conduct safety and risk evaluations, incident investigations, studies of train operations, :...

Energy analysis of cool, medium, and dark roofs on residential buildings in the U.S

NASA Astrophysics Data System (ADS)

Dunbar, Michael A.

This study reports an energy analysis of cool, medium, and dark roofs on residential buildings in the U.S. Three analyses were undertaken in this study: energy consumption, economic analysis, and an environmental analysis. The energy consumption reports the electricity and natural gas consumption of the simulations. The economic analysis uses tools such as simple payback period (SPP) and net present value (NPV) to determine the profitability of the cool roof and the medium roof. The variable change for each simulation model was the roof color. The default color was a dark roof and the results were focused on the changes produced by the cool roof and the medium roof. The environmental analysis uses CO2 emissions to assess the environmental impact of the cool roof and the medium roof. The analysis uses the U.S. Department of Energy (DOE) EnergyPlus software to produce simulations of a typical, two-story residential home in the U.S. The building details of the typical, two-story U.S. residential home and the International Energy Conservation Code (IECC) building code standards used are discussed in this study. This study indicates that, when material and labor costs are. assessed, the cool roof and the medium roof do not yield a SPP less than 10 years. Furthermore, the NPV results assess that neither the cool roof nor the medium roof are a profitable investment in any climate zone in the U.S. The environmental analysis demonstrates that both the cool roof and the medium roof have a positive impact in warmer climates by reducing the CO2 emissions as much as 264 kg and 129 kg, respectively.

KINETIC ENERGY FROM SUPERNOVA FEEDBACK IN HIGH-RESOLUTION GALAXY SIMULATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simpson, Christine M.; Bryan, Greg L.; Ostriker, Jeremiah P.

We describe a new method for adding a prescribed amount of kinetic energy to simulated gas modeled on a cartesian grid by directly altering grid cells’ mass and velocity in a distributed fashion. The method is explored in the context of supernova (SN) feedback in high-resolution (∼10 pc) hydrodynamic simulations of galaxy formation. Resolution dependence is a primary consideration in our application of the method, and simulations of isolated explosions (performed at different resolutions) motivate a resolution-dependent scaling for the injected fraction of kinetic energy that we apply in cosmological simulations of a 10{sup 9} M{sub ⊙} dwarf halo. Wemore » find that in high-density media (≳50 cm{sup −3}) with coarse resolution (≳4 pc per cell), results are sensitive to the initial kinetic energy fraction due to early and rapid cooling. In our galaxy simulations, the deposition of small amounts of SN energy in kinetic form (as little as 1%) has a dramatic impact on the evolution of the system, resulting in an order-of-magnitude suppression of stellar mass. The overall behavior of the galaxy in the two highest resolution simulations we perform appears to converge. We discuss the resulting distribution of stellar metallicities, an observable sensitive to galactic wind properties, and find that while the new method demonstrates increased agreement with observed systems, significant discrepancies remain, likely due to simplistic assumptions that neglect contributions from SNe Ia and stellar winds.« less

Energy consumption program: A computer model simulating energy loads in buildings

NASA Technical Reports Server (NTRS)

Stoller, F. W.; Lansing, F. L.; Chai, V. W.; Higgins, S.

1978-01-01

The JPL energy consumption computer program developed as a useful tool in the on-going building modification studies in the DSN energy conservation project is described. The program simulates building heating and cooling loads and computes thermal and electric energy consumption and cost. The accuracy of computations are not sacrificed, however, since the results lie within + or - 10 percent margin compared to those read from energy meters. The program is carefully structured to reduce both user's time and running cost by asking minimum information from the user and reducing many internal time-consuming computational loops. Many unique features were added to handle two-level electronics control rooms not found in any other program.

Inclusion of Structural Flexibility in Design Load Analysis for Wave Energy Converters: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Yi; Yu, Yi-Hsiang; van Rij, Jennifer A

2017-08-14

Hydroelastic interactions, caused by ocean wave loading on wave energy devices with deformable structures, are studied in the time domain. A midfidelity, hybrid modeling approach of rigid-body and flexible-body dynamics is developed and implemented in an open-source simulation tool for wave energy converters (WEC-Sim) to simulate the dynamic responses of wave energy converter component structural deformations under wave loading. A generalized coordinate system, including degrees of freedom associated with rigid bodies, structural modes, and constraints connecting multiple bodies, is utilized. A simplified method of calculating stress loads and sectional bending moments is implemented, with the purpose of sizing and designingmore » wave energy converters. Results calculated using the method presented are verified with those of high-fidelity fluid-structure interaction simulations, as well as low-fidelity, frequency-domain, boundary element method analysis.« less

Free energy of steps using atomistic simulations

NASA Astrophysics Data System (ADS)

Freitas, Rodrigo; Frolov, Timofey; Asta, Mark

The properties of solid-liquid interfaces are known to play critical roles in solidification processes. Particularly special importance is given to thermodynamic quantities that describe the equilibrium state of these surfaces. For example, on the solid-liquid-vapor heteroepitaxial growth of semiconductor nanowires the crystal nucleation process on the faceted solid-liquid interface is influenced by the solid-liquid and vapor-solid interfacial free energies, and also by the free energies of associated steps at these faceted interfaces. Crystal-growth theories and mesoscale simulation methods depend on quantitative information about these properties, which are often poorly characterized from experimental measurements. In this work we propose an extension of the capillary fluctuation method for calculation of the free energy of steps on faceted crystal surfaces. From equilibrium atomistic simulations of steps on (111) surfaces of Copper we computed accurately the step free energy for different step orientations. We show that the step free energy remains finite at all temperature up to the melting point and that the results obtained agree with the more well established method of thermodynamic integration if finite size effects are taken into account. The research of RF and MA at UC Berkeley were supported by the US National Science Foundation (Grant No. DMR-1105409). TF acknowledges support through a postdoctoral fellowship from the Miller Institute for Basic Research in Science.

SIVEH: numerical computing simulation of wireless energy-harvesting sensor nodes.

PubMed

Sanchez, Antonio; Blanc, Sara; Climent, Salvador; Yuste, Pedro; Ors, Rafael

2013-09-04

The paper presents a numerical energy harvesting model for sensor nodes, SIVEH (Simulator I-V for EH), based on I-V hardware tracking. I-V tracking is demonstrated to be more accurate than traditional energy modeling techniques when some of the components present different power dissipation at either different operating voltages or drawn currents. SIVEH numerical computing allows fast simulation of long periods of time-days, weeks, months or years-using real solar radiation curves. Moreover, SIVEH modeling has been enhanced with sleep time rate dynamic adjustment, while seeking energy-neutral operation. This paper presents the model description, a functional verification and a critical comparison with the classic energy approach.

Simulating drought impacts on energy balance in an Amazonian rainforest

NASA Astrophysics Data System (ADS)

Imbuzeiro, H. A.; Costa, M. H.; Galbraith, D.; Christoffersen, B. O.; Powell, T.; Harper, A. B.; Levine, N. M.; Rowland, L.; Moorcroft, P. R.; Benezoli, V. H.; Meir, P.; da Costa, A. C. L.; Brando, P. M.; Malhi, Y.; Saleska, S. R.; Williams, M. D.

2014-12-01

The studies of the interaction between vegetation and climate change in the Amazon Basin indicate that up to half of the region's forests may be displaced by savanna vegetation by the end of the century. Additional analyses suggest that complex interactions among land use, fire-frequency, and episodic drought are driving an even more rapid process of the forest impoverishment and displacement referred here as "savannization". But it is not clear whether surface/ecosystem models are suitable to analyze extreme events like a drought. Long-term simulations of throughfall exclusion experiments has provided unique insights into the energy dynamics of Amazonian rainforests during drought conditions. In this study, we evaluate how well six surface/ecosystem models quantify the energy dynamics from two Amazonian throughfall exclusion experiments. All models were run for the Tapajós and Caxiuanã sites with one control plot using normal precipitation (i.e. do not impose a drought) and then the drought manipulation was imposed for several drought treatments (10 to 90% rainfall exclusion). The sap flow, net radiation (Rn), sensible (H), latent (LE) and ground (G) heat flux are used to analyze if the models are able to capture the dynamics of water stress and what the implications for the energy dynamics are. With respect to the model validation, when we compare the sap flow observed and transpiration simulated, models are more accurate to simulate control plots than drought treatments (50% rainfall exclusion). The results show that the models overestimate the sap flow data during the drought conditions, but they were able to capture the changes in the main energy balance components for different drought treatments. The Rn and LE decreased and H increased with more intensity of drought. The models sensitivity analysis indicate that models are more sensitive to drought when rainfall is excluded for more than 60% and when this reduction occurs during the dry season.

Impact Testing and Simulation of a Sinusoid Foam Sandwich Energy Absorber

NASA Technical Reports Server (NTRS)

Jackson, Karen E.; Fasanella, Edwin L; Littell, Justin D.

2015-01-01

A sinusoidal-shaped foam sandwich energy absorber was developed and evaluated at NASA Langley Research Center through multi-level testing and simulation performed under the Transport Rotorcraft Airframe Crash Testbed (TRACT) research project. The energy absorber, designated the "sinusoid," consisted of hybrid carbon- Kevlar® plain weave fabric face sheets, two layers for each face sheet oriented at +/-45deg with respect to the vertical or crush direction, and a closed-cell ELFOAM(TradeMark) P200 polyisocyanurate (2.0-lb/ft3) foam core. The design goal for the energy absorber was to achieve an average floor-level acceleration of between 25- and 40-g during the full-scale crash test of a retrofitted CH-46E helicopter airframe, designated TRACT 2. Variations in the design were assessed through quasi-static and dynamic crush testing of component specimens. Once the design was finalized, a 5-ft-long subfloor beam was fabricated and retrofitted into a barrel section of a CH-46E helicopter. A vertical drop test of the barrel section was conducted onto concrete to evaluate the performance of the energy absorber prior to retrofit into TRACT 2. Finite element models were developed of all test articles and simulations were performed using LSDYNA ®, a commercial nonlinear explicit transient dynamic finite element code. Test analysis results are presented for the sinusoid foam sandwich energy absorber as comparisons of load-displacement and acceleration-time-history responses, as well as predicted and experimental structural deformations and progressive damage for each evaluation level (component testing through barrel section drop testing).

Digital computer simulation of inductor-energy-storage dc-to-dc converters with closed-loop regulators

NASA Technical Reports Server (NTRS)

Ohri, A. K.; Owen, H. A.; Wilson, T. G.; Rodriguez, G. E.

1974-01-01

The simulation of converter-controller combinations by means of a flexible digital computer program which produces output to a graphic display is discussed. The procedure is an alternative to mathematical analysis of converter systems. The types of computer programming involved in the simulation are described. Schematic diagrams, state equations, and output equations are displayed for four basic forms of inductor-energy-storage dc to dc converters. Mathematical models are developed to show the relationship of the parameters.

Atomistic observation and simulation analysis of spatio-temporal fluctuations during radiation-induced amorphization.

PubMed

Watanabe, Seiichi; Hoshino, Misaki; Koike, Takuto; Suda, Takanori; Ohnuki, Soumei; Takahashi, Heishichirou; Lam, Nighi Q

2003-01-01

We performed a dynamical-atomistic study of radiation-induced amorphization in the NiTi intermetallic compound using in situ high-resolution high-voltage electron microscopy and molecular dynamics simulations in connection with image simulation. Spatio-temporal fluctuations as non-equilibrium fluctuations in an energy-dissipative system, due to transient atom-cluster formation during amorphization, were revealed by the present spatial autocorrelation analysis.

Validation studies of the DOE-2 Building Energy Simulation Program. Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sullivan, R.; Winkelmann, F.

1998-06-01

This report documents many of the validation studies (Table 1) of the DOE-2 building energy analysis simulation program that have taken place since 1981. Results for several versions of the program are presented with the most recent study conducted in 1996 on version DOE-2.1E and the most distant study conducted in 1981 on version DOE-1.3. This work is part of an effort related to continued development of DOE-2, particularly in its use as a simulation engine for new specialized versions of the program such as the recently released RESFEN 3.1. RESFEN 3.1 is a program specifically dealing with analyzing themore » energy performance of windows in residential buildings. The intent in providing the results of these validation studies is to give potential users of the program a high degree of confidence in the calculated results. Validation studies in which calculated simulation data is compared to measured data have been conducted throughout the development of the DOE-2 program. Discrepancies discovered during the course of such work has resulted in improvements in the simulation algorithms. Table 2 provides a listing of additions and modifications that have been made to various versions of the program since version DOE-2.1A. One of the most significant recent changes in the program occurred with version DOE-2.1E. An improved algorithm for calculating the outside surface film coefficient was implemented. In addition, integration of the WINDOW 4 program was accomplished resulting in improved ability in analyzing window energy performance. Validation and verification of a program as sophisticated as DOE-2 must necessarily be limited because of the approximations inherent in the program. For example, the most accurate model of the heat transfer processes in a building would include a three-dimensional analysis. To justify such detailed algorithmic procedures would correspondingly require detailed information describing the building and/or HVAC system and energy plant

Serious simulation game development for energy transition education using integrated framework game design

NASA Astrophysics Data System (ADS)

Destyanto, A. R.; Putri, O. A.; Hidayatno, A.

2017-11-01

Due to the advantages that serious simulation game offered, many areas of studies, including energy, have used serious simulation games as their instruments. However, serious simulation games in the field of energy transition still have few attentions. In this study, serious simulation game is developed and tested as the activity of public education about energy transition which is a conversion from oil to natural gas program. The aim of the game development is to create understanding and awareness about the importance of energy transition for society in accelerating the process of energy transition in Indonesia since 1987 the energy transition program has not achieved the conversion target yet due to the lack of education about energy transition for society. Developed as a digital serious simulation game following the framework of integrated game design, the Transergy game has been tested to 15 users and then analysed. The result of verification and validation of the game shows that Transergy gives significance to the users for understanding and triggering the needs of oil to natural gas conversion.

Simulating evolution of technology: An aid to energy policy analysis. A case study of strategies to control greenhouse gases in Canada

NASA Astrophysics Data System (ADS)

Nyboer, John

Issues related to the reduction of greenhouse gases are encumbered with uncertainties for decision makers. Unfortunately, conventional analytical tools generate widely divergent forecasts of the effects of actions designed to mitigate these emissions. "Bottom-up" models show the costs of reducing emissions attained through the penetration of efficient technologies to be low or negative. In contrast, more aggregate "top-down" models show costs of reduction to be high. The methodological approaches of the different models used to simulate energy consumption generate, in part, the divergence found in model outputs. To address this uncertainty and bring convergence, I use a technology-explicit model that simulates turnover of equipment stock as a function of detailed data on equipment costs and stock characteristics and of verified behavioural data related to equipment acquisition and retrofitting. Such detail can inform the decision maker of the effects of actions to reduce greenhouse gases due to changes in (1) technology stocks, (2) products or services, or (3) the mix of fuels used. This thesis involves two main components: (1) the development of a quantitative model to analyse energy demand and (2) the application of this tool to a policy issue, abatement of COsb2 emissions. The analysis covers all of Canada by sector (8 industrial subsectors, residential commercial) and region. An electricity supply model to provide local electricity prices supplemented the quantitative model. Forecasts of growth and structural change were provided by national macroeconomic models. Seven different simulations were applied to each sector in each region including a base case run and three runs simulating emissions charges of 75/tonne, 150/tonne and 225/tonne CO sb2. The analysis reveals that there is significant variation in the costs and quantity of emissions reduction by sector and region. Aggregated results show that Canada can meet both stabilisation targets (1990 levels of

Evaluation of Emerging Energy-Efficient Heterogeneous Computing Platforms for Biomolecular and Cellular Simulation Workloads.

PubMed

Stone, John E; Hallock, Michael J; Phillips, James C; Peterson, Joseph R; Luthey-Schulten, Zaida; Schulten, Klaus

2016-05-01

Many of the continuing scientific advances achieved through computational biology are predicated on the availability of ongoing increases in computational power required for detailed simulation and analysis of cellular processes on biologically-relevant timescales. A critical challenge facing the development of future exascale supercomputer systems is the development of new computing hardware and associated scientific applications that dramatically improve upon the energy efficiency of existing solutions, while providing increased simulation, analysis, and visualization performance. Mobile computing platforms have recently become powerful enough to support interactive molecular visualization tasks that were previously only possible on laptops and workstations, creating future opportunities for their convenient use for meetings, remote collaboration, and as head mounted displays for immersive stereoscopic viewing. We describe early experiences adapting several biomolecular simulation and analysis applications for emerging heterogeneous computing platforms that combine power-efficient system-on-chip multi-core CPUs with high-performance massively parallel GPUs. We present low-cost power monitoring instrumentation that provides sufficient temporal resolution to evaluate the power consumption of individual CPU algorithms and GPU kernels. We compare the performance and energy efficiency of scientific applications running on emerging platforms with results obtained on traditional platforms, identify hardware and algorithmic performance bottlenecks that affect the usability of these platforms, and describe avenues for improving both the hardware and applications in pursuit of the needs of molecular modeling tasks on mobile devices and future exascale computers.

Evaluation of Emerging Energy-Efficient Heterogeneous Computing Platforms for Biomolecular and Cellular Simulation Workloads

PubMed Central

Stone, John E.; Hallock, Michael J.; Phillips, James C.; Peterson, Joseph R.; Luthey-Schulten, Zaida; Schulten, Klaus

2016-01-01

Many of the continuing scientific advances achieved through computational biology are predicated on the availability of ongoing increases in computational power required for detailed simulation and analysis of cellular processes on biologically-relevant timescales. A critical challenge facing the development of future exascale supercomputer systems is the development of new computing hardware and associated scientific applications that dramatically improve upon the energy efficiency of existing solutions, while providing increased simulation, analysis, and visualization performance. Mobile computing platforms have recently become powerful enough to support interactive molecular visualization tasks that were previously only possible on laptops and workstations, creating future opportunities for their convenient use for meetings, remote collaboration, and as head mounted displays for immersive stereoscopic viewing. We describe early experiences adapting several biomolecular simulation and analysis applications for emerging heterogeneous computing platforms that combine power-efficient system-on-chip multi-core CPUs with high-performance massively parallel GPUs. We present low-cost power monitoring instrumentation that provides sufficient temporal resolution to evaluate the power consumption of individual CPU algorithms and GPU kernels. We compare the performance and energy efficiency of scientific applications running on emerging platforms with results obtained on traditional platforms, identify hardware and algorithmic performance bottlenecks that affect the usability of these platforms, and describe avenues for improving both the hardware and applications in pursuit of the needs of molecular modeling tasks on mobile devices and future exascale computers. PMID:27516922

Essential energy space random walk via energy space metadynamics method to accelerate molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Li, Hongzhi; Min, Donghong; Liu, Yusong; Yang, Wei

2007-09-01

To overcome the possible pseudoergodicity problem, molecular dynamic simulation can be accelerated via the realization of an energy space random walk. To achieve this, a biased free energy function (BFEF) needs to be priori obtained. Although the quality of BFEF is essential for sampling efficiency, its generation is usually tedious and nontrivial. In this work, we present an energy space metadynamics algorithm to efficiently and robustly obtain BFEFs. Moreover, in order to deal with the associated diffusion sampling problem caused by the random walk in the total energy space, the idea in the original umbrella sampling method is generalized to be the random walk in the essential energy space, which only includes the energy terms determining the conformation of a region of interest. This essential energy space generalization allows the realization of efficient localized enhanced sampling and also offers the possibility of further sampling efficiency improvement when high frequency energy terms irrelevant to the target events are free of activation. The energy space metadynamics method and its generalization in the essential energy space for the molecular dynamics acceleration are demonstrated in the simulation of a pentanelike system, the blocked alanine dipeptide model, and the leucine model.

Free-energy analyses of a proton transfer reaction by simulated-tempering umbrella sampling and first-principles molecular dynamics simulations.

PubMed

Mori, Yoshiharu; Okamoto, Yuko

2013-02-01

A simulated tempering method, which is referred to as simulated-tempering umbrella sampling, for calculating the free energy of chemical reactions is proposed. First principles molecular dynamics simulations with this simulated tempering were performed to study the intramolecular proton transfer reaction of malonaldehyde in an aqueous solution. Conformational sampling in reaction coordinate space can be easily enhanced with this method, and the free energy along a reaction coordinate can be calculated accurately. Moreover, the simulated-tempering umbrella sampling provides trajectory data more efficiently than the conventional umbrella sampling method.

A New Maximum Likelihood Approach for Free Energy Profile Construction from Molecular Simulations

PubMed Central

Lee, Tai-Sung; Radak, Brian K.; Pabis, Anna; York, Darrin M.

2013-01-01

A novel variational method for construction of free energy profiles from molecular simulation data is presented. The variational free energy profile (VFEP) method uses the maximum likelihood principle applied to the global free energy profile based on the entire set of simulation data (e.g from multiple biased simulations) that spans the free energy surface. The new method addresses common obstacles in two major problems usually observed in traditional methods for estimating free energy surfaces: the need for overlap in the re-weighting procedure and the problem of data representation. Test cases demonstrate that VFEP outperforms other methods in terms of the amount and sparsity of the data needed to construct the overall free energy profiles. For typical chemical reactions, only ~5 windows and ~20-35 independent data points per window are sufficient to obtain an overall qualitatively correct free energy profile with sampling errors an order of magnitude smaller than the free energy barrier. The proposed approach thus provides a feasible mechanism to quickly construct the global free energy profile and identify free energy barriers and basins in free energy simulations via a robust, variational procedure that determines an analytic representation of the free energy profile without the requirement of numerically unstable histograms or binning procedures. It can serve as a new framework for biased simulations and is suitable to be used together with other methods to tackle with the free energy estimation problem. PMID:23457427

Energy dynamics in a simulation of LAPD turbulence

NASA Astrophysics Data System (ADS)

Friedman, B.; Carter, T. A.; Umansky, M. V.; Schaffner, D.; Dudson, B.

2012-10-01

Energy dynamics calculations in a 3D fluid simulation of drift wave turbulence in the linear Large Plasma Device [W. Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] illuminate processes that drive and dissipate the turbulence. These calculations reveal that a nonlinear instability dominates the injection of energy into the turbulence by overtaking the linear drift wave instability that dominates when fluctuations about the equilibrium are small. The nonlinear instability drives flute-like (k∥=0) density fluctuations using free energy from the background density gradient. Through nonlinear axial wavenumber transfer to k∥≠0 fluctuations, the nonlinear instability accesses the adiabatic response, which provides the requisite energy transfer channel from density to potential fluctuations as well as the phase shift that causes instability. The turbulence characteristics in the simulations agree remarkably well with experiment. When the nonlinear instability is artificially removed from the system through suppressing k∥=0 modes, the turbulence develops a coherent frequency spectrum which is inconsistent with experimental data. This indicates the importance of the nonlinear instability in producing experimentally consistent turbulence.

Design, modeling, simulation and evaluation of a distributed energy system

NASA Astrophysics Data System (ADS)

Cultura, Ambrosio B., II

This dissertation presents the design, modeling, simulation and evaluation of distributed energy resources (DER) consisting of photovoltaics (PV), wind turbines, batteries, a PEM fuel cell and supercapacitors. The distributed energy resources installed at UMass Lowell consist of the following: 2.5kW PV, 44kWhr lead acid batteries and 1500W, 500W & 300W wind turbines, which were installed before year 2000. Recently added to that are the following: 10.56 kW PV array, 2.4 kW wind turbine, 29 kWhr Lead acid batteries, a 1.2 kW PEM fuel cell and 4-140F supercapacitors. Each newly added energy resource has been designed, modeled, simulated and evaluated before its integration into the existing PV/Wind grid-connected system. The Mathematical and Simulink model of each system was derived and validated by comparing the simulated and experimental results. The Simulated results of energy generated from a 10.56kW PV system are in good agreement with the experimental results. A detailed electrical model of a 2.4kW wind turbine system equipped with a permanent magnet generator, diode rectifier, boost converter and inverter is presented. The analysis of the results demonstrates the effectiveness of the constructed simulink model, and can be used to predict the performance of the wind turbine. It was observed that a PEM fuel cell has a very fast response to load changes. Moreover, the model has validated the actual operation of the PEM fuel cell, showing that the simulated results in Matlab Simulink are consistent with the experimental results. The equivalent mathematical equation, derived from an electrical model of the supercapacitor, is used to simulate its voltage response. The model is completely capable of simulating its voltage behavior, and can predict the charge time and discharge time of voltages on the supercapacitor. The bi-directional dc-dc converter was designed in order to connect the 48V battery bank storage to the 24V battery bank storage. This connection was

Simulation Speed Analysis and Improvements of Modelica Models for Building Energy Simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jorissen, Filip; Wetter, Michael; Helsen, Lieve

This paper presents an approach for speeding up Modelica models. Insight is provided into how Modelica models are solved and what determines the tool’s computational speed. Aspects such as algebraic loops, code efficiency and integrator choice are discussed. This is illustrated using simple building simulation examples and Dymola. The generality of the work is in some cases verified using OpenModelica. Using this approach, a medium sized office building including building envelope, heating ventilation and air conditioning (HVAC) systems and control strategy can be simulated at a speed five hundred times faster than real time.

SIVEH: Numerical Computing Simulation of Wireless Energy-Harvesting Sensor Nodes

PubMed Central

Sanchez, Antonio; Blanc, Sara; Climent, Salvador; Yuste, Pedro; Ors, Rafael

2013-01-01

The paper presents a numerical energy harvesting model for sensor nodes, SIVEH (Simulator I–V for EH), based on I–V hardware tracking. I–V tracking is demonstrated to be more accurate than traditional energy modeling techniques when some of the components present different power dissipation at either different operating voltages or drawn currents. SIVEH numerical computing allows fast simulation of long periods of time—days, weeks, months or years—using real solar radiation curves. Moreover, SIVEH modeling has been enhanced with sleep time rate dynamic adjustment, while seeking energy-neutral operation. This paper presents the model description, a functional verification and a critical comparison with the classic energy approach. PMID:24008287

Materials, Chemistry, and Simulation for Future Energy Technology.

PubMed

Aguey-Zinsou, Kondo-Francois; Wang, Da-Wei; Su, Dang-Sheng

2015-09-07

Special Issue: The Future of Energy. The science and engineering of clean energy now is becoming a multidisciplinary area, typically when new materials, chemistry, or mechanisms are met. "Trial and error" is the past. Exploration of new concepts for future clean energy can be accomplished through computer-aided materials design and reaction simulation, thanks to innovations in information technologies. This special issue, a fruit of the Energy Future Conference organized by UNSW Australia, has compiled some excellent examples of such approaches. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Energy landscape paving simulations of the trp-cage protein.

PubMed

Schug, Alexander; Wenzel, Wolfgang; Hansmann, Ulrich H E

2005-05-15

We evaluate the efficiency of multiple variants of energy landscape paving in all-atom simulations of the trp-cage protein using a recently developed new force field. Especially, we introduce a temperature-free variant of the method and demonstrate that it allows a fast scanning of the energy landscape. Nativelike structures are found in less time than by other techniques. The sampled low-energy configurations indicate a funnel-like energy landscape.

Chemical Dynamics Simulations of Intermolecular Energy Transfer: Azulene + N2 Collisions.

PubMed

Kim, Hyunsik; Paul, Amit K; Pratihar, Subha; Hase, William L

2016-07-14

Chemical dynamics simulations were performed to investigate collisional energy transfer from highly vibrationally excited azulene (Az*) in a N2 bath. The intermolecular potential between Az and N2, used for the simulations, was determined from MP2/6-31+G* ab initio calculations. Az* is prepared with an 87.5 kcal/mol excitation energy by using quantum microcanonical sampling, including its 95.7 kcal/mol zero-point energy. The average energy of Az* versus time, obtained from the simulations, shows different rates of Az* deactivation depending on the N2 bath density. Using the N2 bath density and Lennard-Jones collision number, the average energy transfer per collision ⟨ΔEc⟩ was obtained for Az* as it is collisionally relaxed. By comparing ⟨ΔEc⟩ versus the bath density, the single collision limiting density was found for energy transfer. The resulting ⟨ΔEc⟩, for an 87.5 kcal/mol excitation energy, is 0.30 ± 0.01 and 0.32 ± 0.01 kcal/mol for harmonic and anharmonic Az potentials, respectively. For comparison, the experimental value is 0.57 ± 0.11 kcal/mol. During Az* relaxation there is no appreciable energy transfer to Az translation and rotation, and the energy transfer is to the N2 bath.

Analysis of EnergyPlus for use in residential building energy optimization

NASA Astrophysics Data System (ADS)

Spencer, Justin S.

This work explored the utility of EnergyPlus as a simulation engine for doing residential building energy optimization, with the objective of finding the modeling areas that require further development in EnergyPlus for residential optimization applications. This work was conducted primarily during 2006-2007, with publication occurring later in 2010. The assessments and recommendations apply to the simulation tool versions available in 2007. During this work, an EnergyPlus v2.0 (2007) input file generator was developed for use in BEopt 0.8.0.4 (2007). BEopt 0.8.0.4 is a residential Building Energy optimization program developed at the National Renewable Energy Laboratory in Golden, Colorado. Residential modeling capabilities of EnergyPlus v2.0 were scrutinized and tested. Modeling deficiencies were identified in a number of areas. These deficiencies were compared to deficiencies in the DOE2.2 V44E4(2007)/TRNSYS simulation engines. The highest priority gaps in EnergyPlus v2.0's residential modeling capability are in infiltration, duct leakage, and foundation modeling. Optimization results from DOE2.2 V44E4 and EnergyPlus v2.0 were analyzed to search for modeling differences that have a significant impact on optimization results. Optimal buildings at different energy savings levels were compared to look for biases. It was discovered that the EnergyPlus v2.0 optimizations consistently chose higher wall insulation levels than the DOE2.2 V44E4 optimizations. The points composing the optimal paths chosen by DOE2.2 V44E4 and EnergyPlus v2.0 were compared to look for points chosen by one optimization that were significantly different from the other optimal path. These outliers were compared to consensus optimal points to determine the simulation differences that cause disparities in the optimization results. The differences were primarily caused by modeling of window radiation exchange and HVAC autosizing.

Binding mode analysis, dynamic simulation and binding free energy calculations of the MurF ligase from Acinetobacter baumannii.

PubMed

Ahmad, Sajjad; Raza, Saad; Uddin, Reaz; Azam, Syed Sikander

2017-10-01

MurF ligase catalyzes the final cytoplasmic step of bacterial peptidoglycan biosynthesis and, as such, is a validated target for therapeutic intervention. Herein, we performed molecular docking to identify putative inhibitors of Acinetobacter baumannii MurF (AbMurF). Based on comparative docking analysis, compound 114 (ethyl pyridine substituted 3-cyanothiophene) was predicted to potentially be the most active ligand. Computational pharmacokinetic characterization of drug-likeness of the compound showed it to fulfil all the parameters of Muegge and the MDDR rule. A molecular dynamic simulation of 114 indicated the complex to be stable on the basis of an average root mean square deviation (RMSD) value of 2.09Å for the ligand. The stability of the complex was further supported by root mean square fluctuation (RMSF), beta factor and radius of gyration values. Analyzing the complex using radial distribution function (RDF) and a novel analytical tool termed the axial frequency distribution (AFD) illustrated that after simulation the ligand is positioned in close vicinity of the protein active site where Thr42 and Asp43 participate in hydrogen bonding and stabilization of the complex. Binding free energy calculations based on the Poisson-Boltzmann or Generalized-Born Surface Area Continuum Solvation (MM(PB/GB)SA) method indicated the van der Waals contribution to the overall binding energy of the complex to be dominant along with electrostatic contributions involving the hot spot amino acids from the protein active site. The present results indicate that the screened compound 114 may act as a parent structure for designing potent derivatives against AbMurF in specific and MurF of other bacterial pathogens in general. Copyright © 2017 Elsevier Inc. All rights reserved.

Optimal reconstruction of the folding landscape using differential energy surface analysis

NASA Astrophysics Data System (ADS)

La Porta, Arthur; Denesyuk, Natalia A.; de Messieres, Michel

2013-03-01

In experiments and in simulations, the free energy of a state of a system can be determined from the probability that the state is occupied. However, it is often necessary to impose a biasing potential on the system so that high energy states are sampled with sufficient frequency. The unbiased energy is typically obtained from the data using the weighted histogram analysis method (WHAM). Here we present differential energy surface analysis (DESA), in which the gradient of the energy surface, dE/dx, is extracted from data taken with a series of harmonic biasing potentials. It is shown that DESA produces a maximum likelihood estimate of the folding landscape gradient. DESA is demonstrated by analyzing data from a simulated system as well as data from a single-molecule unfolding experiment in which the end-to-end distance of a DNA hairpin is measured. It is shown that the energy surface obtained from DESA is indistinguishable from the energy surface obtained when WHAM is applied to the same data. Two criteria are defined which indicate whether the DESA results are self-consistent. It is found that these criteria can detect a situation where the energy is not a single-valued function of the measured reaction coordinate. The criteria were found to be satisfied for the experimental data analyzed, confirming that end-to-end distance is a good reaction coordinate for the experimental system. The combination of DESA and the optical trap assay in which a structure is disrupted under harmonic constraint facilitates an extremely accurate measurement of the folding energy surface.

A comparison of renewable energy technologies using two simulation softwares: HOMER and RETScreen

NASA Astrophysics Data System (ADS)

Ramli, Mohd Sufian; Wahid, Siti Sufiah Abd; Hassan, Khairul Kamarudin

2017-08-01

This paper concerns on modelling renewable energy technologies including PV standalone system (PVSS) and wind standalone system (WSS) as well as PV-wind hybrid system (PVWHS). To evaluate the performance of all power system configurations in term of economic analysis and optimization, simulation tools called HOMER and RETScreen are used in this paper. HOMER energy modeling software is a powerful tool for designing and analyzing hybrid power systems, which contains a mix of conventional generators, wind turbines, solar photovoltaic's, hydropower, batteries, and other inputs. RETScreen uses a Microsoft Excel-based spreadsheet model that consists of a set of workbooks which calculates the annual average energy flows with adjustment factors to account for temporal effects such as solar-load coincidence. Sizes of equipments are calculated and inserted as inputs to HOMER and RETScreen. The result obtained are analyzed and discussed. The cost per kWh to generate electricity using the PVSS system to supply the average demand of 8.4 kWh/day ranges between RM 1.953/kWh to RM 3.872/kWh. It has been found that the PVSS gives the lowest cost of energy compared to the other proposed two technologies that have been simulated by using HOMER and RETScreen.

Monte Carlo simulation of energy deposition by low-energy electrons in molecular hydrogen

NASA Technical Reports Server (NTRS)

Heaps, M. G.; Furman, D. R.; Green, A. E. S.

1975-01-01

A set of detailed atomic cross sections has been used to obtain the spatial deposition of energy by 1-20-eV electrons in molecular hydrogen by a Monte Carlo simulation of the actual trajectories. The energy deposition curve (energy per distance traversed) is quite peaked in the forward direction about the entry point for electrons with energies above the threshold of the electronic states, but the peak decreases and broadens noticeably as the electron energy decreases below 10 eV (threshold for the lowest excitable electronic state of H2). The curve also assumes a very symmetrical shape for energies below 10 eV, indicating the increasing importance of elastic collisions in determining the shape of the curve, although not the mode of energy deposition.

Research on simulation system with the wide range and high-precision laser energy characteristics

NASA Astrophysics Data System (ADS)

Dong, Ke-yan; Lou, Yan; He, Jing-yi; Tong, Shou-feng; Jiang, Hui-lin

2012-10-01

The Hardware-in-the-loop(HWIL) simulation test is one of the important parts for the development and performance testing of semi-active laser-guided weapons. In order to obtain accurate results, the confidence level of the target environment should be provided for a high-seeker during the HWIL simulation test of semi-active laser-guided weapons, and one of the important simulation parameters is the laser energy characteristic. In this paper, based on the semi-active laser-guided weapon guidance principles, an important parameter of simulation of confidence which affects energy characteristics in performance test of HWIL simulation was analyzed. According to the principle of receiving the same energy by using HWIL simulation and in practical application, HWIL energy characteristics simulation systems with the crystal absorption structure was designed. And on this basis, the problems of optimal design of the optical system were also analyzed. The measured results show that the dynamic attenuation range of the system energy is greater than 50dB, the dynamic attenuation stability is less than 5%, and the maximum energy changing rate driven by the servo motor is greater than 20dB/s.

A SOFTWARE TOOL TO COMPARE MEASURED AND SIMULATED BUILDING ENERGY PERFORMANCE DATA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maile, Tobias; Bazjanac, Vladimir; O'Donnell, James

2011-11-01

Building energy performance is often inadequate when compared to design goals. To link design goals to actual operation one can compare measured with simulated energy performance data. Our previously developed comparison approach is the Energy Performance Comparison Methodology (EPCM), which enables the identification of performance problems based on a comparison of measured and simulated performance data. In context of this method, we developed a software tool that provides graphing and data processing capabilities of the two performance data sets. The software tool called SEE IT (Stanford Energy Efficiency Information Tool) eliminates the need for manual generation of data plots andmore » data reformatting. SEE IT makes the generation of time series, scatter and carpet plots independent of the source of data (measured or simulated) and provides a valuable tool for comparing measurements with simulation results. SEE IT also allows assigning data points on a predefined building object hierarchy and supports different versions of simulated performance data. This paper briefly introduces the EPCM, describes the SEE IT tool and illustrates its use in the context of a building case study.« less

Building energy simulation in real time through an open standard interface

DOE PAGES

Pang, Xiufeng; Nouidui, Thierry S.; Wetter, Michael; ...

2015-10-20

Building energy models (BEMs) are typically used for design and code compliance for new buildings and in the renovation of existing buildings to predict energy use. We present the increasing adoption of BEM as standard practice in the building industry presents an opportunity to extend the use of BEMs into construction, commissioning and operation. In 2009, the authors developed a real-time simulation framework to execute an EnergyPlus model in real time to improve building operation. This paper reports an enhancement of that real-time energy simulation framework. The previous version only works with software tools that implement the custom co-simulation interfacemore » of the Building Controls Virtual Test Bed (BCVTB), such as EnergyPlus, Dymola and TRNSYS. The new version uses an open standard interface, the Functional Mockup Interface (FMI), to provide a generic interface to any application that supports the FMI protocol. In addition, the new version utilizes the Simple Measurement and Actuation Profile (sMAP) tool as the data acquisition system to acquire, store and present data. Lastly, this paper introduces the updated architecture of the real-time simulation framework using FMI and presents proof-of-concept demonstration results which validate the new framework.« less

Free energy landscape of the Michaelis complex of lactate dehydrogenase: A network analysis of atomistic simulations

NASA Astrophysics Data System (ADS)

Pan, Xiaoliang; Schwartz, Steven

2015-03-01

It has long been recognized that the structure of a protein is a hierarchy of conformations interconverting on multiple time scales. However, the conformational heterogeneity is rarely considered in the context of enzymatic catalysis in which the reactant is usually represented by a single conformation of the enzyme/substrate complex. Lactate dehydrogenase (LDH) catalyzes the interconversion of pyruvate and lactate with concomitant interconversion of two forms of the cofactor nicotinamide adenine dinucleotide (NADH and NAD+). Recent experimental results suggest that multiple substates exist within the Michaelis complex of LDH, and they are catalytic competent at different reaction rates. In this study, millisecond-scale all-atom molecular dynamics simulations were performed on LDH to explore the free energy landscape of the Michaelis complex, and network analysis was used to characterize the distribution of the conformations. Our results provide a detailed view of the kinetic network the Michaelis complex and the structures of the substates at atomistic scale. It also shed some light on understanding the complete picture of the catalytic mechanism of LDH.

Free energy surface of the Michaelis complex of lactate dehydrogenase: a network analysis of microsecond simulations.

PubMed

Pan, Xiaoliang; Schwartz, Steven D

2015-04-30

It has long been recognized that the structure of a protein creates a hierarchy of conformations interconverting on multiple time scales. The conformational heterogeneity of the Michaelis complex is of particular interest in the context of enzymatic catalysis in which the reactant is usually represented by a single conformation of the enzyme/substrate complex. Lactate dehydrogenase (LDH) catalyzes the interconversion of pyruvate and lactate with concomitant interconversion of two forms of the cofactor nicotinamide adenine dinucleotide (NADH and NAD(+)). Recent experimental results suggest that multiple substates exist within the Michaelis complex of LDH, and they show a strong variance in their propensity toward the on-enzyme chemical step. In this study, microsecond-scale all-atom molecular dynamics simulations were performed on LDH to explore the free energy landscape of the Michaelis complex, and network analysis was used to characterize the distribution of the conformations. Our results provide a detailed view of the kinetic network of the Michaelis complex and the structures of the substates at atomistic scales. They also shed light on the complete picture of the catalytic mechanism of LDH.

XIMPOL: a new x-ray polarimetry observation-simulation and analysis framework

NASA Astrophysics Data System (ADS)

Omodei, Nicola; Baldini, Luca; Pesce-Rollins, Melissa; di Lalla, Niccolò

2017-08-01

We present a new simulation framework, XIMPOL, based on the python programming language and the Scipy stack, specifically developed for X-ray polarimetric applications. XIMPOL is not tied to any specific mission or instrument design and is meant to produce fast and yet realistic observation-simulations, given as basic inputs: (i) an arbitrary source model including morphological, temporal, spectral and polarimetric information, and (ii) the response functions of the detector under study, i.e., the effective area, the energy dispersion, the point-spread function and the modulation factor. The format of the response files is OGIP compliant, and the framework has the capability of producing output files that can be directly fed into the standard visualization and analysis tools used by the X-ray community, including XSPEC which make it a useful tool not only for simulating physical systems, but also to develop and test end-to-end analysis chains.

Simplified energy-balance model for pragmatic multi-dimensional device simulation

NASA Astrophysics Data System (ADS)

Chang, Duckhyun; Fossum, Jerry G.

1997-11-01

To pragmatically account for non-local carrier heating and hot-carrier effects such as velocity overshoot and impact ionization in multi-dimensional numerical device simulation, a new simplified energy-balance (SEB) model is developed and implemented in FLOODS[16] as a pragmatic option. In the SEB model, the energy-relaxation length is estimated from a pre-process drift-diffusion simulation using the carrier-velocity distribution predicted throughout the device domain, and is used without change in a subsequent simpler hydrodynamic (SHD) simulation. The new SEB model was verified by comparison of two-dimensional SHD and full HD DC simulations of a submicron MOSFET. The SHD simulations yield detailed distributions of carrier temperature, carrier velocity, and impact-ionization rate, which agree well with the full HD simulation results obtained with FLOODS. The most noteworthy feature of the new SEB/SHD model is its computational efficiency, which results from reduced Newton iteration counts caused by the enhanced linearity. Relative to full HD, SHD simulation times can be shorter by as much as an order of magnitude since larger voltage steps for DC sweeps and larger time steps for transient simulations can be used. The improved computational efficiency can enable pragmatic three-dimensional SHD device simulation as well, for which the SEB implementation would be straightforward as it is in FLOODS or any robust HD simulator.

Energy demand hourly simulations and energy saving strategies in greenhouses for the Mediterranean climate

NASA Astrophysics Data System (ADS)

Priarone, A.; Fossa, M.; Paietta, E.; Rolando, D.

2017-01-01

This research has been devoted to the selection of the most favourable plant solutions for ventilation, heating and cooling, thermo-hygrometric control of a greenhouse, in the framework of the energy saving and the environmental protection. The identified plant solutions include shading of glazing surfaces, natural ventilation by means of controlled opening windows, forced convection of external air and forced convection of air treated by the HVAC system for both heating and cooling. The selected solution combines HVAC system to a Ground Coupled Heat Pump (GCHP), which is an innovative renewable technology applied to greenhouse buildings. The energy demand and thermal loads of the greenhouse to fulfil the requested internal design conditions have been evaluated through an hourly numerical simulation, using the Energy Plus (E-plus) software. The overall heat balance of the greenhouse also includes the latent heat exchange due to crop evapotranspiration, accounted through an original iterative calculation procedure that combines the E-plus dynamic simulations and the FAO Penman-Monteith method. The obtained hourly thermal loads have been used to size the borehole field for the geothermal heat pump by using a dedicated GCHP hourly simulation tool.

Free Energy, Enthalpy and Entropy from Implicit Solvent End-Point Simulations.

PubMed

Fogolari, Federico; Corazza, Alessandra; Esposito, Gennaro

2018-01-01

Free energy is the key quantity to describe the thermodynamics of biological systems. In this perspective we consider the calculation of free energy, enthalpy and entropy from end-point molecular dynamics simulations. Since the enthalpy may be calculated as the ensemble average over equilibrated simulation snapshots the difficulties related to free energy calculation are ultimately related to the calculation of the entropy of the system and in particular of the solvent entropy. In the last two decades implicit solvent models have been used to circumvent the problem and to take into account solvent entropy implicitly in the solvation terms. More recently outstanding advancement in both implicit solvent models and in entropy calculations are making the goal of free energy estimation from end-point simulations more feasible than ever before. We review briefly the basic theory and discuss the advancements in light of practical applications.

System-of-Systems Approach for Integrated Energy Systems Modeling and Simulation: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mittal, Saurabh; Ruth, Mark; Pratt, Annabelle

Today’s electricity grid is the most complex system ever built—and the future grid is likely to be even more complex because it will incorporate distributed energy resources (DERs) such as wind, solar, and various other sources of generation and energy storage. The complexity is further augmented by the possible evolution to new retail market structures that provide incentives to owners of DERs to support the grid. To understand and test new retail market structures and technologies such as DERs, demand-response equipment, and energy management systems while providing reliable electricity to all customers, an Integrated Energy System Model (IESM) is beingmore » developed at NREL. The IESM is composed of a power flow simulator (GridLAB-D), home energy management systems implemented using GAMS/Pyomo, a market layer, and hardware-in-the-loop simulation (testing appliances such as HVAC, dishwasher, etc.). The IESM is a system-of-systems (SoS) simulator wherein the constituent systems are brought together in a virtual testbed. We will describe an SoS approach for developing a distributed simulation environment. We will elaborate on the methodology and the control mechanisms used in the co-simulation illustrated by a case study.« less

A simulation model for wind energy storage systems. Volume 1: Technical report

NASA Technical Reports Server (NTRS)

Warren, A. W.; Edsinger, R. W.; Chan, Y. K.

1977-01-01

A comprehensive computer program for the modeling of wind energy and storage systems utilizing any combination of five types of storage (pumped hydro, battery, thermal, flywheel and pneumatic) was developed. The level of detail of Simulation Model for Wind Energy Storage (SIMWEST) is consistent with a role of evaluating the economic feasibility as well as the general performance of wind energy systems. The software package consists of two basic programs and a library of system, environmental, and load components. The first program is a precompiler which generates computer models (in FORTRAN) of complex wind source storage application systems, from user specifications using the respective library components. The second program provides the techno-economic system analysis with the respective I/O, the integration of systems dynamics, and the iteration for conveyance of variables. SIMWEST program, as described, runs on the UNIVAC 1100 series computers.

Influence of photon energy cuts on PET Monte Carlo simulation results.

PubMed

Mitev, Krasimir; Gerganov, Georgi; Kirov, Assen S; Schmidtlein, C Ross; Madzhunkov, Yordan; Kawrakow, Iwan

2012-07-01

The purpose of this work is to study the influence of photon energy cuts on the results of positron emission tomography (PET) Monte Carlo (MC) simulations. MC simulations of PET scans of a box phantom and the NEMA image quality phantom are performed for 32 photon energy cut values in the interval 0.3-350 keV using a well-validated numerical model of a PET scanner. The simulations are performed with two MC codes, egs_pet and GEANT4 Application for Tomographic Emission (GATE). The effect of photon energy cuts on the recorded number of singles, primary, scattered, random, and total coincidences as well as on the simulation time and noise-equivalent count rate is evaluated by comparing the results for higher cuts to those for 1 keV cut. To evaluate the effect of cuts on the quality of reconstructed images, MC generated sinograms of PET scans of the NEMA image quality phantom are reconstructed with iterative statistical reconstruction. The effects of photon cuts on the contrast recovery coefficients and on the comparison of images by means of commonly used similarity measures are studied. For the scanner investigated in this study, which uses bismuth germanate crystals, the transport of Bi X(K) rays must be simulated in order to obtain unbiased estimates for the number of singles, true, scattered, and random coincidences as well as for an unbiased estimate of the noise-equivalent count rate. Photon energy cuts higher than 170 keV lead to absorption of Compton scattered photons and strongly increase the number of recorded coincidences of all types and the noise-equivalent count rate. The effect of photon cuts on the reconstructed images and the similarity measures used for their comparison is statistically significant for very high cuts (e.g., 350 keV). The simulation time decreases slowly with the increase of the photon cut. The simulation of the transport of characteristic x rays plays an important role, if an accurate modeling of a PET scanner system is to be achieved

Comparison of Building Loads Analysis and System Thermodynamics (BLAST) Computer Program Simulations and Measured Energy Use for Army Buildings.

DTIC Science & Technology

1980-05-01

engineering ,ZteNo D R RPTE16 research w 9 laboratory COMPARISON OF BUILDING LOADS ANALYSIS AND SYSTEM THERMODYNAMICS (BLAST) AD 0 5 5,0 3COMPUTER PROGRAM...Building Loads Analysis and System Thermodynamics (BLAST) computer program. A dental clinic and a battalion headquarters and classroom building were...Building and HVAC System Data Computer Simulation Comparison of Actual and Simulated Results ANALYSIS AND FINDINGS

Energy consumption analysis for various memristive networks under different learning strategies

NASA Astrophysics Data System (ADS)

Deng, Lei; Wang, Dong; Zhang, Ziyang; Tang, Pei; Li, Guoqi; Pei, Jing

2016-02-01

Recently, various memristive systems emerge to emulate the efficient computing paradigm of the brain cortex; whereas, how to make them energy efficient still remains unclear, especially from an overall perspective. Here, a systematical and bottom-up energy consumption analysis is demonstrated, including the memristor device level and the network learning level. We propose an energy estimating methodology when modulating the memristive synapses, which is simulated in three typical neural networks with different synaptic structures and learning strategies for both offline and online learning. These results provide an in-depth insight to create energy efficient brain-inspired neuromorphic devices in the future.

Numerical models analysis of energy conversion process in air-breathing laser propulsion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong Yanji; Song Junling; Cui Cunyan

Energy source was considered as a key essential in this paper to describe energy conversion process in air-breathing laser propulsion. Some secondary factors were ignored when three independent modules, ray transmission module, energy source term module and fluid dynamic module, were established by simultaneous laser radiation transportation equation and fluid mechanics equation. The incidence laser beam was simulated based on ray tracing method. The calculated results were in good agreement with those of theoretical analysis and experiments.

Building energy analysis tool

DOEpatents

Brackney, Larry; Parker, Andrew; Long, Nicholas; Metzger, Ian; Dean, Jesse; Lisell, Lars

2016-04-12

A building energy analysis system includes a building component library configured to store a plurality of building components, a modeling tool configured to access the building component library and create a building model of a building under analysis using building spatial data and using selected building components of the plurality of building components stored in the building component library, a building analysis engine configured to operate the building model and generate a baseline energy model of the building under analysis and further configured to apply one or more energy conservation measures to the baseline energy model in order to generate one or more corresponding optimized energy models, and a recommendation tool configured to assess the one or more optimized energy models against the baseline energy model and generate recommendations for substitute building components or modifications.

Plans for wind energy system simulation

NASA Technical Reports Server (NTRS)

Dreier, M. E.

1978-01-01

A digital computer code and a special purpose hybrid computer, were introduced. The digital computer program, the Root Perturbation Method or RPM, is an implementation of the classic floquet procedure which circumvents numerical problems associated with the extraction of Floquet roots. The hybrid computer, the Wind Energy System Time domain simulator (WEST), yields real time loads and deformation information essential to design and system stability investigations.

Summary of: Simulating the Value of Concentrating Solar Power with Thermal Energy Storage in a Production Cost Model (Presentation)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Denholm, P.; Hummon, M.

2013-02-01

Concentrating solar power (CSP) deployed with thermal energy storage (TES) provides a dispatchable source of renewable energy. The value of CSP with TES, as with other potential generation resources, needs to be established using traditional utility planning tools. Production cost models, which simulate the operation of grid, are often used to estimate the operational value of different generation mixes. CSP with TES has historically had limited analysis in commercial production simulations. This document describes the implementation of CSP with TES in a commercial production cost model. It also describes the simulation of grid operations with CSP in a test systemmore » consisting of two balancing areas located primarily in Colorado.« less

Simulations of eddy kinetic energy transport in barotropic turbulence

NASA Astrophysics Data System (ADS)

Grooms, Ian

2017-11-01

Eddy energy transport in rotating two-dimensional turbulence is investigated using numerical simulation. Stochastic forcing is used to generate an inhomogeneous field of turbulence and the time-mean energy profile is diagnosed. An advective-diffusive model for the transport is fit to the simulation data by requiring the model to accurately predict the observed time-mean energy distribution. Isotropic harmonic diffusion of energy is found to be an accurate model in the case of uniform, solid-body background rotation (the f plane), with a diffusivity that scales reasonably well with a mixing-length law κ ∝V ℓ , where V and ℓ are characteristic eddy velocity and length scales. Passive tracer dynamics are added and it is found that the energy diffusivity is 75 % of the tracer diffusivity. The addition of a differential background rotation with constant vorticity gradient β leads to significant changes to the energy transport. The eddies generate and interact with a mean flow that advects the eddy energy. Mean advection plus anisotropic diffusion (with reduced diffusivity in the direction of the background vorticity gradient) is moderately accurate for flows with scale separation between the eddies and mean flow, but anisotropic diffusion becomes a much less accurate model of the transport when scale separation breaks down. Finally, it is observed that the time-mean eddy energy does not look like the actual eddy energy distribution at any instant of time. In the future, stochastic models of the eddy energy transport may prove more useful than models of the mean transport for predicting realistic eddy energy distributions.

FESetup: Automating Setup for Alchemical Free Energy Simulations.

PubMed

Loeffler, Hannes H; Michel, Julien; Woods, Christopher

2015-12-28

FESetup is a new pipeline tool which can be used flexibly within larger workflows. The tool aims to support fast and easy setup of alchemical free energy simulations for molecular simulation packages such as AMBER, GROMACS, Sire, or NAMD. Post-processing methods like MM-PBSA and LIE can be set up as well. Ligands are automatically parametrized with AM1-BCC, and atom mappings for a single topology description are computed with a maximum common substructure search (MCSS) algorithm. An abstract molecular dynamics (MD) engine can be used for equilibration prior to free energy setup or standalone. Currently, all modern AMBER force fields are supported. Ease of use, robustness of the code, and automation where it is feasible are the main development goals. The project follows an open development model, and we welcome contributions.

Magnetoacoustic Wave Energy from Numerical Simulations of an Observed Sunspot Umbra

NASA Astrophysics Data System (ADS)

Felipe, T.; Khomenko, E.; Collados, M.

2011-07-01

We aim at reproducing the height dependence of sunspot wave signatures obtained from spectropolarimetric observations through three-dimensional MHD numerical simulations. A magnetostatic sunspot model based on the properties of the observed sunspot is constructed and perturbed at the photosphere, introducing the fluctuations measured with the Si I λ10827 line. The results of the simulations are compared with the oscillations observed simultaneously at different heights from the He I λ10830 line, the Ca II H core, and the Fe I blends in the wings of the Ca II H line. The simulations show a remarkable agreement with the observations. They reproduce the velocity maps and power spectra at the formation heights of the observed lines, as well as the phase and amplification spectra between several pairs of lines. We find that the stronger shocks at the chromosphere are accompanied with a delay between the observed signal and the simulated one at the corresponding height, indicating that shocks shift the formation height of the chromospheric lines to higher layers. Since the simulated wave propagation matches very well the properties of the observed one, we are able to use the numerical calculations to quantify the energy contribution of the magnetoacoustic waves to the chromospheric heating in sunspots. Our findings indicate that the energy supplied by these waves is too low to balance the chromospheric radiative losses. The energy contained at the formation height of the lowermost Si I λ10827 line in the form of slow magnetoacoustic waves is already insufficient to heat the higher layers, and the acoustic energy which reaches the chromosphere is around 3-9 times lower than the required amount of energy. The contribution of the magnetic energy is even lower.

Simulation of Flywheel Energy Storage System

DTIC Science & Technology

2006-01-01

currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) 02/11/06 2. REPORT TYPE...Government Purpose Rights 14. ABSTRACT Presented is a comprehensive power model for the Flywheel Attitude Control , Energy Transmission, and Storage...flywheel units and the Agile Multi-Purpose Satellite Simulator (AMPSS). The purpose of FACETS is to demonstrate integrated attitude control maneuvers

The mesoscale forcing of a midlatitude upper-tropospheric jet streak by a simulated convective system. 2: Kinetic energy and resolution analysis

NASA Technical Reports Server (NTRS)

Wolf, Bart J.; Johnson, D. R.

1995-01-01

A kinetic energy (KE) analysis of the forcing of a mesoscale upper-tropospheric jet streak by organized diabatic processes within the simulated convective system (SCS) that was discussed in Part 1 is presented in this study. The relative contributions of the ageostrophic components of motion to the generation of KE of the convectively generated jet streak are compared, along with the KE generation by the rotational (nondivergent) and irrotational (divergent) mass transport. The sensitivity of the numerical simulations of SCS development to resolution is also briefly examined. Analysis within isentropic coordinates provides for an explicit determination of the influence of the diabatic processes on the generation of KE. The upper-level production of specific KE is due predominatly to the inertial advective ageostrophic component (IAD), and as such represents the primary process through which the KE of the convectively generated jet streak is realized. A secondary contribution by the inertial diabatic (IDI) term is observed. Partitioning the KE generation into its rotational and irrotational components reveals that the latter, which is directly linked to the diabatic heating within the SCS through isentropic continuity requirements, is the ultimate source of KE generation as the global area integral of generation by the rotational component vanishes. Comparison with an identical dry simulation reveals that the net generation of KE must be attributed to latent heating. Both the IAD and IDI ageostrophic components play important roles in this regard. Examination of results from simulations conducted at several resolutions supports the previous findings in that the effects of diabatic processes and ageostrophic motion on KE generation remain consistent. Resolution does impact the location and timing of SCS development, a result that has important implications in forecasting the onset of convection that develops from evolution of the large-scale flow and moisture

Dihedral angle principal component analysis of molecular dynamics simulations.

PubMed

Altis, Alexandros; Nguyen, Phuong H; Hegger, Rainer; Stock, Gerhard

2007-06-28

It has recently been suggested by Mu et al. [Proteins 58, 45 (2005)] to use backbone dihedral angles instead of Cartesian coordinates in a principal component analysis of molecular dynamics simulations. Dihedral angles may be advantageous because internal coordinates naturally provide a correct separation of internal and overall motion, which was found to be essential for the construction and interpretation of the free energy landscape of a biomolecule undergoing large structural rearrangements. To account for the circular statistics of angular variables, a transformation from the space of dihedral angles {phi(n)} to the metric coordinate space {x(n)=cos phi(n),y(n)=sin phi(n)} was employed. To study the validity and the applicability of the approach, in this work the theoretical foundations underlying the dihedral angle principal component analysis (dPCA) are discussed. It is shown that the dPCA amounts to a one-to-one representation of the original angle distribution and that its principal components can readily be characterized by the corresponding conformational changes of the peptide. Furthermore, a complex version of the dPCA is introduced, in which N angular variables naturally lead to N eigenvalues and eigenvectors. Applying the methodology to the construction of the free energy landscape of decaalanine from a 300 ns molecular dynamics simulation, a critical comparison of the various methods is given.

Dihedral angle principal component analysis of molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Altis, Alexandros; Nguyen, Phuong H.; Hegger, Rainer; Stock, Gerhard

2007-06-01

It has recently been suggested by Mu et al. [Proteins 58, 45 (2005)] to use backbone dihedral angles instead of Cartesian coordinates in a principal component analysis of molecular dynamics simulations. Dihedral angles may be advantageous because internal coordinates naturally provide a correct separation of internal and overall motion, which was found to be essential for the construction and interpretation of the free energy landscape of a biomolecule undergoing large structural rearrangements. To account for the circular statistics of angular variables, a transformation from the space of dihedral angles {φn} to the metric coordinate space {xn=cosφn,yn=sinφn} was employed. To study the validity and the applicability of the approach, in this work the theoretical foundations underlying the dihedral angle principal component analysis (dPCA) are discussed. It is shown that the dPCA amounts to a one-to-one representation of the original angle distribution and that its principal components can readily be characterized by the corresponding conformational changes of the peptide. Furthermore, a complex version of the dPCA is introduced, in which N angular variables naturally lead to N eigenvalues and eigenvectors. Applying the methodology to the construction of the free energy landscape of decaalanine from a 300ns molecular dynamics simulation, a critical comparison of the various methods is given.

Morse-Smale Analysis of Ion Diffusion in Ab Initio Battery Materials Simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gyulassy, Attila; Knoll, Aaron; Lau, Kah Chun

Ab initio molecular dynamics (AIMD) simulations are increasingly useful in modeling, optimizing and synthesizing materials in energy sciences. In solving Schrödinger’s equation, they generate the electronic structure of the simulated atoms as a scalar field. However, methods for analyzing these volume data are not yet common in molecular visualization. The Morse-Smale complex is a proven, versatile tool for topological analysis of scalar fields. In this paper, we apply the discrete Morse-Smale complex to analysis of first-principles battery materials simulations. We consider a carbon nanosphere structure used in battery materials research, and employ Morse-Smale decomposition to determine the possible lithium ionmore » diffusion paths within that structure. Our approach is novel in that it uses the wavefunction itself as opposed distance fields, and that we analyze the 1-skeleton of the Morse-Smale complex to reconstruct our diffusion paths. Furthermore, it is the first application where specific motifs in the graph structure of the complete 1-skeleton define features, namely carbon rings with specific valence. We compare our analysis of DFT data with that of a distance field approximation, and discuss implications on larger classical molecular dynamics simulations.« less

Investigation of allosteric modulation mechanism of metabotropic glutamate receptor 1 by molecular dynamics simulations, free energy and weak interaction analysis

NASA Astrophysics Data System (ADS)

Bai, Qifeng; Yao, Xiaojun

2016-02-01

Metabotropic glutamate receptor 1 (mGlu1), which belongs to class C G protein-coupled receptors (GPCRs), can be coupled with G protein to transfer extracellular signal by dimerization and allosteric regulation. Unraveling the dimer packing and allosteric mechanism can be of great help for understanding specific regulatory mechanism and designing more potential negative allosteric modulator (NAM). Here, we report molecular dynamics simulation studies of the modulation mechanism of FITM on the wild type, T815M and Y805A mutants of mGlu1 through weak interaction analysis and free energy calculation. The weak interaction analysis demonstrates that van der Waals (vdW) and hydrogen bonding play an important role on the dimer packing between six cholesterol molecules and mGlu1 as well as the interaction between allosteric sites T815, Y805 and FITM in wild type, T815M and Y805A mutants of mGlu1. Besides, the results of free energy calculations indicate that secondary binding pocket is mainly formed by the residues Thr748, Cys746, Lys811 and Ser735 except for FITM-bound pocket in crystal structure. Our results can not only reveal the dimer packing and allosteric regulation mechanism, but also can supply useful information for the design of potential NAM of mGlu1.

Simulation of High Energy Emission from Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Ziaeepour, Houri

Gamma-Ray Bursts (GRBs) are the must violent explosions after the Big-Bang. Their high energy radiation can potentially carry information about the most inner part of the accretion disk of a collapsing star, ionize the surrounding material in the host galaxy, and thereby influence the process of star formation specially in the dense environment at high redshifts. They can also have a significant contribution in the formation of high energy cosmic-rays. Here we present new simulations of GRBs according to a dynamically consistent relativistic shock model for the prompt emission, with or without the presence of an magnetic field. They show that the properties of observed bursts are well reproduced by this model up to GeV energies. They help to better understand GRB phenomenon, and provide an insight into characteristics of relativistic jets and particle acceleration which cannot yet be simulated with enough precision from first principles.

Challenges in reducing the computational time of QSTS simulations for distribution system analysis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deboever, Jeremiah; Zhang, Xiaochen; Reno, Matthew J.

The rapid increase in penetration of distributed energy resources on the electric power distribution system has created a need for more comprehensive interconnection modelling and impact analysis. Unlike conventional scenario - based studies , quasi - static time - series (QSTS) simulation s can realistically model time - dependent voltage controllers and the diversity of potential impacts that can occur at different times of year . However, to accurately model a distribution system with all its controllable devices, a yearlong simulation at 1 - second resolution is often required , which could take conventional computers a computational time of 10more » to 120 hours when an actual unbalanced distribution feeder is modeled . This computational burden is a clear l imitation to the adoption of QSTS simulation s in interconnection studies and for determining optimal control solutions for utility operations . Our ongoing research to improve the speed of QSTS simulation has revealed many unique aspects of distribution system modelling and sequential power flow analysis that make fast QSTS a very difficult problem to solve. In this report , the most relevant challenges in reducing the computational time of QSTS simulations are presented: number of power flows to solve, circuit complexity, time dependence between time steps, multiple valid power flow solutions, controllable element interactions, and extensive accurate simulation analysis.« less

Advanced computational simulations of water waves interacting with wave energy converters

NASA Astrophysics Data System (ADS)

Pathak, Ashish; Freniere, Cole; Raessi, Mehdi

2017-03-01

Wave energy converter (WEC) devices harness the renewable ocean wave energy and convert it into useful forms of energy, e.g. mechanical or electrical. This paper presents an advanced 3D computational framework to study the interaction between water waves and WEC devices. The computational tool solves the full Navier-Stokes equations and considers all important effects impacting the device performance. To enable large-scale simulations in fast turnaround times, the computational solver was developed in an MPI parallel framework. A fast multigrid preconditioned solver is introduced to solve the computationally expensive pressure Poisson equation. The computational solver was applied to two surface-piercing WEC geometries: bottom-hinged cylinder and flap. Their numerically simulated response was validated against experimental data. Additional simulations were conducted to investigate the applicability of Froude scaling in predicting full-scale WEC response from the model experiments.

A virtual laboratory for the simulation of sustainable energy systems in a low energy building: A case study

NASA Astrophysics Data System (ADS)

Breen, M.; O'Donovan, A.; Murphy, M. D.; Delaney, F.; Hill, M.; Sullivan, P. D. O.

2016-03-01

The aim of this paper was to develop a virtual laboratory simulation platform of the National Building Retrofit Test-bed at the Cork Institute of Technology, Ireland. The building in question is a low-energy retrofit which is provided with electricity by renewable systems including photovoltaics and wind. It can be thought of as a living laboratory, as a number of internal and external building factors are recorded at regular intervals during human occupation. The analysis carried out in this paper demonstrated that, for the period from April to September 2015, the electricity provided by the renewable systems did not consistently match the building’s electricity requirements due to differing load profiles. It was concluded that the use of load shifting techniques may help to increase the percentage of renewable energy utilisation.

Toward prethreshold gate-based quantum simulation of chemical dynamics: using potential energy surfaces to simulate few-channel molecular collisions

DOE PAGES

Sornborger, Andrew Tyler; Stancil, Phillip; Geller, Michael R.

2018-03-22

Here, one of the most promising applications of an error-corrected universal quantum computer is the efficient simulation of complex quantum systems such as large molecular systems. In this application, one is interested in both the electronic structure such as the ground state energy and dynamical properties such as the scattering cross section and chemical reaction rates. However, most theoretical work and experimental demonstrations have focused on the quantum computation of energies and energy surfaces. In this work, we attempt to make the prethreshold (not error-corrected) quantum simulation of dynamical properties practical as well. We show that the use of precomputedmore » potential energy surfaces and couplings enables the gate-based simulation of few-channel but otherwise realistic molecular collisions. Our approach is based on the widely used Born–Oppenheimer approximation for the structure problem coupled with a semiclassical method for the dynamics. In the latter the electrons are treated quantum mechanically but the nuclei are classical, which restricts the collisions to high energy or temperature (typically above ≈10 eV). By using operator splitting techniques optimized for the resulting time-dependent Hamiltonian simulation problem, we give several physically realistic collision examples, with 3–8 channels and circuit depths < 1000.« less

Toward prethreshold gate-based quantum simulation of chemical dynamics: using potential energy surfaces to simulate few-channel molecular collisions

NASA Astrophysics Data System (ADS)

Sornborger, Andrew T.; Stancil, Phillip; Geller, Michael R.

2018-05-01

One of the most promising applications of an error-corrected universal quantum computer is the efficient simulation of complex quantum systems such as large molecular systems. In this application, one is interested in both the electronic structure such as the ground state energy and dynamical properties such as the scattering cross section and chemical reaction rates. However, most theoretical work and experimental demonstrations have focused on the quantum computation of energies and energy surfaces. In this work, we attempt to make the prethreshold (not error-corrected) quantum simulation of dynamical properties practical as well. We show that the use of precomputed potential energy surfaces and couplings enables the gate-based simulation of few-channel but otherwise realistic molecular collisions. Our approach is based on the widely used Born-Oppenheimer approximation for the structure problem coupled with a semiclassical method for the dynamics. In the latter the electrons are treated quantum mechanically but the nuclei are classical, which restricts the collisions to high energy or temperature (typically above ≈ 10 eV). By using operator splitting techniques optimized for the resulting time-dependent Hamiltonian simulation problem, we give several physically realistic collision examples, with 3-8 channels and circuit depths < 1000.

Toward prethreshold gate-based quantum simulation of chemical dynamics: using potential energy surfaces to simulate few-channel molecular collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sornborger, Andrew Tyler; Stancil, Phillip; Geller, Michael R.

Here, one of the most promising applications of an error-corrected universal quantum computer is the efficient simulation of complex quantum systems such as large molecular systems. In this application, one is interested in both the electronic structure such as the ground state energy and dynamical properties such as the scattering cross section and chemical reaction rates. However, most theoretical work and experimental demonstrations have focused on the quantum computation of energies and energy surfaces. In this work, we attempt to make the prethreshold (not error-corrected) quantum simulation of dynamical properties practical as well. We show that the use of precomputedmore » potential energy surfaces and couplings enables the gate-based simulation of few-channel but otherwise realistic molecular collisions. Our approach is based on the widely used Born–Oppenheimer approximation for the structure problem coupled with a semiclassical method for the dynamics. In the latter the electrons are treated quantum mechanically but the nuclei are classical, which restricts the collisions to high energy or temperature (typically above ≈10 eV). By using operator splitting techniques optimized for the resulting time-dependent Hamiltonian simulation problem, we give several physically realistic collision examples, with 3–8 channels and circuit depths < 1000.« less

An energy function for dynamics simulations of polypeptides in torsion angle space

NASA Astrophysics Data System (ADS)

Sartori, F.; Melchers, B.; Böttcher, H.; Knapp, E. W.

1998-05-01

Conventional simulation techniques to model the dynamics of proteins in atomic detail are restricted to short time scales. A simplified molecular description, in which high frequency motions with small amplitudes are ignored, can overcome this problem. In this protein model only the backbone dihedrals φ and ψ and the χi of the side chains serve as degrees of freedom. Bond angles and lengths are fixed at ideal geometry values provided by the standard molecular dynamics (MD) energy function CHARMM. In this work a Monte Carlo (MC) algorithm is used, whose elementary moves employ cooperative rotations in a small window of consecutive amide planes, leaving the polypeptide conformation outside of this window invariant. A single of these window MC moves generates local conformational changes only. But, the application of many such moves at different parts of the polypeptide backbone leads to global conformational changes. To account for the lack of flexibility in the protein model employed, the energy function used to evaluate conformational energies is split into sequentially neighbored and sequentially distant contributions. The sequentially neighbored part is represented by an effective (φ,ψ)-torsion potential. It is derived from MD simulations of a flexible model dipeptide using a conventional MD energy function. To avoid exaggeration of hydrogen bonding strengths, the electrostatic interactions involving hydrogen atoms are scaled down at short distances. With these adjustments of the energy function, the rigid polypeptide model exhibits the same equilibrium distributions as obtained by conventional MD simulation with a fully flexible molecular model. Also, the same temperature dependence of the stability and build-up of α helices of 18-alanine as found in MD simulations is observed using the adapted energy function for MC simulations. Analyses of transition frequencies demonstrate that also dynamical aspects of MD trajectories are faithfully reproduced. Finally

Coarse-Grained Simulations of Protein-Protein Association: An Energy Landscape Perspective

PubMed Central

Ravikumar, Krishnakumar M.; Huang, Wei; Yang, Sichun

2012-01-01

Understanding protein-protein association is crucial in revealing the molecular basis of many biological processes. Here, we describe a theoretical simulation pipeline to study protein-protein association from an energy landscape perspective. First, a coarse-grained model is implemented and its applications are demonstrated via molecular dynamics simulations for several protein complexes. Second, an enhanced search method is used to efficiently sample a broad range of protein conformations. Third, multiple conformations are identified and clustered from simulation data and further projected on a three-dimensional globe specifying protein orientations and interacting energies. Results from several complexes indicate that the crystal-like conformation is favorable on the energy landscape even if the landscape is relatively rugged with metastable conformations. A closer examination on molecular forces shows that the formation of associated protein complexes can be primarily electrostatics-driven, hydrophobics-driven, or a combination of both in stabilizing specific binding interfaces. Taken together, these results suggest that the coarse-grained simulations and analyses provide an alternative toolset to study protein-protein association occurring in functional biomolecular complexes. PMID:22947945

DES Y1 Results: Validating Cosmological Parameter Estimation Using Simulated Dark Energy Surveys

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacCrann, N.; et al.

We use mock galaxy survey simulations designed to resemble the Dark Energy Survey Year 1 (DES Y1) data to validate and inform cosmological parameter estimation. When similar analysis tools are applied to both simulations and real survey data, they provide powerful validation tests of the DES Y1 cosmological analyses presented in companion papers. We use two suites of galaxy simulations produced using different methods, which therefore provide independent tests of our cosmological parameter inference. The cosmological analysis we aim to validate is presented in DES Collaboration et al. (2017) and uses angular two-point correlation functions of galaxy number counts and weak lensing shear, as well as their cross-correlation, in multiple redshift bins. While our constraints depend on the specific set of simulated realisations available, for both suites of simulations we find that the input cosmology is consistent with the combined constraints from multiple simulated DES Y1 realizations in themore » $$\\Omega_m-\\sigma_8$$ plane. For one of the suites, we are able to show with high confidence that any biases in the inferred $$S_8=\\sigma_8(\\Omega_m/0.3)^{0.5}$$ and $$\\Omega_m$$ are smaller than the DES Y1 $$1-\\sigma$$ uncertainties. For the other suite, for which we have fewer realizations, we are unable to be this conclusive; we infer a roughly 70% probability that systematic biases in the recovered $$\\Omega_m$$ and $$S_8$$ are sub-dominant to the DES Y1 uncertainty. As cosmological analyses of this kind become increasingly more precise, validation of parameter inference using survey simulations will be essential to demonstrate robustness.« less

The Effects of an Energy-Environment Simulator Upon Selected Energy-Related Attitudes of Science Students and In-Service Teachers.

ERIC Educational Resources Information Center

Dunlop, David L.

This document is the outcome of a study designed to investigate the energy-related attitudes of several different groups of science students and science teachers both before and after working with an energy-environment simulator for approximately an hour. During the interaction with the simulator, the participants decided upon the variables they…

Simulation of Energy Response of the ATIC Calorimeter

NASA Technical Reports Server (NTRS)

Batkov, K. E.; Adams, J. H., Jr.; Ahn, H. S.; Bashindzhagyan, G. L.; Case, G.; Christl, M.; Chang, J.; Fazely, A. R.; Ganel, O.; Granger, D.;

Mechanism of pKID/KIX Association Studied by Molecular Dynamics Free Energy Simulations.

PubMed

Bomblies, Rainer; Luitz, Manuel P; Zacharias, Martin

2016-08-25

The phosphorylated kinase-inducible domain (pKID) associates with the kinase interacting domain (KIX) via a coupled folding and binding mechanism. The pKID domain is intrinsically disordered when unbound and upon phosphorylation at Ser133 binds to the KIX domain adopting a well-defined kinked two-helix structure. In order to identify putative hot spot residues of binding that could serve as an initial stable anchor, we performed in silico alanine scanning free energy simulations. The simulations indicate that charged residues including the phosphorylated central Ser133 of pKID make significant contributions to binding. However, these are of slightly smaller magnitude compared to several hydrophobic side chains not defining a single dominant binding hot spot. Both continuous molecular dynamics (MD) simulations and free energy analysis demonstrate that phosphorylation significantly stabilizes the central kinked motif around Ser133 of pKID and shifts the conformational equilibrium toward the bound conformation already in the absence of KIX. This result supports a view that pKID/KIX association follows in part a conformational selection process. During a 1.5 μs explicit solvent MD simulation, folding of pKID on the surface of KIX was observed after an initial contact at the bound position of the phosphorylation site was enforced following a sequential process of αA helix association and a stepwise association and folding of the second αB helix compatible with available experimental results.

Data Intensive Analysis of Biomolecular Simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Straatsma, TP; Soares, Thereza A.

2007-12-01

The advances in biomolecular modeling and simulation made possible by the availability of increasingly powerful high performance computing resources is extending molecular simulations to biological more relevant system size and time scales. At the same time, advances in simulation methodologies are allowing more complex processes to be described more accurately. These developments make a systems approach to computational structural biology feasible, but this will require a focused emphasis on the comparative analysis of the increasing number of molecular simulations that are being carried out for biomolecular systems with more realistic models, multi-component environments, and for longer simulation times. Just asmore » in the case of the analysis of the large data sources created by the new high-throughput experimental technologies, biomolecular computer simulations contribute to the progress in biology through comparative analysis. The continuing increase in available protein structures allows the comparative analysis of the role of structure and conformational flexibility in protein function, and is the foundation of the discipline of structural bioinformatics. This creates the opportunity to derive general findings from the comparative analysis of molecular dynamics simulations of a wide range of proteins, protein-protein complexes and other complex biological systems. Because of the importance of protein conformational dynamics for protein function, it is essential that the analysis of molecular trajectories is carried out using a novel, more integrative and systematic approach. We are developing a much needed rigorous computer science based framework for the efficient analysis of the increasingly large data sets resulting from molecular simulations. Such a suite of capabilities will also provide the required tools for access and analysis of a distributed library of generated trajectories. Our research is focusing on the following areas: (1) the development

Data Intensive Analysis of Biomolecular Simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Straatsma, TP

2008-03-01

The advances in biomolecular modeling and simulation made possible by the availability of increasingly powerful high performance computing resources is extending molecular simulations to biological more relevant system size and time scales. At the same time, advances in simulation methodologies are allowing more complex processes to be described more accurately. These developments make a systems approach to computational structural biology feasible, but this will require a focused emphasis on the comparative analysis of the increasing number of molecular simulations that are being carried out for biomolecular systems with more realistic models, multi-component environments, and for longer simulation times. Just asmore » in the case of the analysis of the large data sources created by the new high-throughput experimental technologies, biomolecular computer simulations contribute to the progress in biology through comparative analysis. The continuing increase in available protein structures allows the comparative analysis of the role of structure and conformational flexibility in protein function, and is the foundation of the discipline of structural bioinformatics. This creates the opportunity to derive general findings from the comparative analysis of molecular dynamics simulations of a wide range of proteins, protein-protein complexes and other complex biological systems. Because of the importance of protein conformational dynamics for protein function, it is essential that the analysis of molecular trajectories is carried out using a novel, more integrative and systematic approach. We are developing a much needed rigorous computer science based framework for the efficient analysis of the increasingly large data sets resulting from molecular simulations. Such a suite of capabilities will also provide the required tools for access and analysis of a distributed library of generated trajectories. Our research is focusing on the following areas: (1) the development

CALIBRATED ULTRA FAST IMAGE SIMULATIONS FOR THE DARK ENERGY SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruderer, Claudio; Chang, Chihway; Refregier, Alexandre

2016-01-20

Image simulations are becoming increasingly important in understanding the measurement process of the shapes of galaxies for weak lensing and the associated systematic effects. For this purpose we present the first implementation of the Monte Carlo Control Loops (MCCL), a coherent framework for studying systematic effects in weak lensing. It allows us to model and calibrate the shear measurement process using image simulations from the Ultra Fast Image Generator (UFig) and the image analysis software SExtractor. We apply this framework to a subset of the data taken during the Science Verification period (SV) of the Dark Energy Survey (DES). Wemore » calibrate the UFig simulations to be statistically consistent with one of the SV images, which covers ∼0.5 square degrees. We then perform tolerance analyses by perturbing six simulation parameters and study their impact on the shear measurement at the one-point level. This allows us to determine the relative importance of different parameters. For spatially constant systematic errors and point-spread function, the calibration of the simulation reaches the weak lensing precision needed for the DES SV survey area. Furthermore, we find a sensitivity of the shear measurement to the intrinsic ellipticity distribution, and an interplay between the magnitude-size and the pixel value diagnostics in constraining the noise model. This work is the first application of the MCCL framework to data and shows how it can be used to methodically study the impact of systematics on the cosmic shear measurement.« less

Free-energy landscape, principal component analysis, and structural clustering to identify representative conformations from molecular dynamics simulations: the myoglobin case.

PubMed

Papaleo, Elena; Mereghetti, Paolo; Fantucci, Piercarlo; Grandori, Rita; De Gioia, Luca

2009-01-01

Several molecular dynamics (MD) simulations were used to sample conformations in the neighborhood of the native structure of holo-myoglobin (holo-Mb), collecting trajectories spanning 0.22 micros at 300 K. Principal component (PCA) and free-energy landscape (FEL) analyses, integrated by cluster analysis, which was performed considering the position and structures of the individual helices of the globin fold, were carried out. The coherence between the different structural clusters and the basins of the FEL, together with the convergence of parameters derived by PCA indicates that an accurate description of the Mb conformational space around the native state was achieved by multiple MD trajectories spanning at least 0.14 micros. The integration of FEL, PCA, and structural clustering was shown to be a very useful approach to gain an overall view of the conformational landscape accessible to a protein and to identify representative protein substates. This method could be also used to investigate the conformational and dynamical properties of Mb apo-, mutant, or delete versions, in which greater conformational variability is expected and, therefore identification of representative substates from the simulations is relevant to disclose structure-function relationship.

Stochastic Modeling of Overtime Occupancy and Its Application in Building Energy Simulation and Calibration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Kaiyu; Yan, Da; Hong, Tianzhen

2014-02-28

Overtime is a common phenomenon around the world. Overtime drives both internal heat gains from occupants, lighting and plug-loads, and HVAC operation during overtime periods. Overtime leads to longer occupancy hours and extended operation of building services systems beyond normal working hours, thus overtime impacts total building energy use. Current literature lacks methods to model overtime occupancy because overtime is stochastic in nature and varies by individual occupants and by time. To address this gap in the literature, this study aims to develop a new stochastic model based on the statistical analysis of measured overtime occupancy data from an officemore » building. A binomial distribution is used to represent the total number of occupants working overtime, while an exponential distribution is used to represent the duration of overtime periods. The overtime model is used to generate overtime occupancy schedules as an input to the energy model of a second office building. The measured and simulated cooling energy use during the overtime period is compared in order to validate the overtime model. A hybrid approach to energy model calibration is proposed and tested, which combines ASHRAE Guideline 14 for the calibration of the energy model during normal working hours, and a proposed KS test for the calibration of the energy model during overtime. The developed stochastic overtime model and the hybrid calibration approach can be used in building energy simulations to improve the accuracy of results, and better understand the characteristics of overtime in office buildings.« less

Power in the loop real time simulation platform for renewable energy generation

NASA Astrophysics Data System (ADS)

Li, Yang; Shi, Wenhui; Zhang, Xing; He, Guoqing

2018-02-01

Nowadays, a large scale of renewable energy sources has been connecting to power system and the real time simulation platform is widely used to carry out research on integration control algorithm, power system stability etc. Compared to traditional pure digital simulation and hardware in the loop simulation, power in the loop simulation has higher accuracy and degree of reliability. In this paper, a power in the loop analog digital hybrid simulation platform has been built and it can be used not only for the single generation unit connecting to grid, but also for multiple new energy generation units connecting to grid. A wind generator inertia control experiment was carried out on the platform. The structure of the inertia control platform was researched and the results verify that the platform is up to need for renewable power in the loop real time simulation.

Qgui: A high-throughput interface for automated setup and analysis of free energy calculations and empirical valence bond simulations in biological systems.

PubMed

Isaksen, Geir Villy; Andberg, Tor Arne Heim; Åqvist, Johan; Brandsdal, Bjørn Olav

2015-07-01

Structural information and activity data has increased rapidly for many protein targets during the last decades. In this paper, we present a high-throughput interface (Qgui) for automated free energy and empirical valence bond (EVB) calculations that use molecular dynamics (MD) simulations for conformational sampling. Applications to ligand binding using both the linear interaction energy (LIE) method and the free energy perturbation (FEP) technique are given using the estrogen receptor (ERα) as a model system. Examples of free energy profiles obtained using the EVB method for the rate-limiting step of the enzymatic reaction catalyzed by trypsin are also shown. In addition, we present calculation of high-precision Arrhenius plots to obtain the thermodynamic activation enthalpy and entropy with Qgui from running a large number of EVB simulations. Copyright © 2015 Elsevier Inc. All rights reserved.

Transactive Systems Simulation and Valuation Platform Trial Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Widergren, Steven E.; Hammerstrom, Donald J.; Huang, Qiuhua

Transactive energy systems use principles of value to coordinate responsive supply and demand in energy systems. Work continues within the Transactive Systems Program, which is funded by the U.S. Department of Energy at Pacific Northwest National Laboratory, to understand the value of, understand the theory behind, and simulate the behaviors of transactive energy systems. This report summarizes recent advances made by this program. The main capability advances include a more comprehensive valuation model, including recommended documentation that should make valuation studies of all sorts more transparent, definition of economic metrics with which transactive mechanisms can be evaluated, and multiple improvementsmore » to the time-simulation environment that is being used to evaluate transactive scenarios.« less

Simulation of diurnal thermal energy storage systems: Preliminary results

NASA Astrophysics Data System (ADS)

Katipamula, S.; Somasundaram, S.; Williams, H. R.

1994-12-01

This report describes the results of a simulation of thermal energy storage (TES) integrated with a simple-cycle gas turbine cogeneration system. Integrating TES with cogeneration can serve the electrical and thermal loads independently while firing all fuel in the gas turbine. The detailed engineering and economic feasibility of diurnal TES systems integrated with cogeneration systems has been described in two previous PNL reports. The objective of this study was to lay the ground work for optimization of the TES system designs using a simulation tool called TRNSYS (TRaNsient SYstem Simulation). TRNSYS is a transient simulation program with a sequential-modular structure developed at the Solar Energy Laboratory, University of Wisconsin-Madison. The two TES systems selected for the base-case simulations were: (1) a one-tank storage model to represent the oil/rock TES system; and (2) a two-tank storage model to represent the molten nitrate salt TES system. Results of the study clearly indicate that an engineering optimization of the TES system using TRNSYS is possible. The one-tank stratified oil/rock storage model described here is a good starting point for parametric studies of a TES system. Further developments to the TRNSYS library of available models (economizer, evaporator, gas turbine, etc.) are recommended so that the phase-change processes is accurately treated.

Energy deposition evaluation for ultra-low energy electron beam irradiation systems using calibrated thin radiochromic film and Monte Carlo simulations.

PubMed

Matsui, S; Mori, Y; Nonaka, T; Hattori, T; Kasamatsu, Y; Haraguchi, D; Watanabe, Y; Uchiyama, K; Ishikawa, M

2016-05-01

For evaluation of on-site dosimetry and process design in industrial use of ultra-low energy electron beam (ULEB) processes, we evaluate the energy deposition using a thin radiochromic film and a Monte Carlo simulation. The response of film dosimeter was calibrated using a high energy electron beam with an acceleration voltage of 2 MV and alanine dosimeters with uncertainty of 11% at coverage factor 2. Using this response function, the results of absorbed dose measurements for ULEB were evaluated from 10 kGy to 100 kGy as a relative dose. The deviation between the responses of deposit energy on the films and Monte Carlo simulations was within 15%. As far as this limitation, relative dose estimation using thin film dosimeters with response function obtained by high energy electron irradiation and simulation results is effective for ULEB irradiation processes management.

Geospatial Analysis | Energy Analysis | NREL

Science.gov Websites

products and tools. Image of a triangle divided into sections called Market, Economic, Technical, and Featured Study U.S. Renewable Energy Technical Potentials: A GIS-Based Analysis summarizes the achievable energy generation, or technical potential, of specific renewable energy technologies given system

Free Energy Reconstruction from Metadynamics or Adiabatic Free Energy Dynamics Simulations.

PubMed

Cuendet, Michel A; Tuckerman, Mark E

2014-08-12

In molecular dynamics simulations, most enhanced sampling methods are traditionally associated with one particular estimator to calculate the free energy surface (FES), such as the histogram, the mean force, or the bias potential. Here, we start from the realization that four enhanced sampling methods, metadynamics and well-tempered metadynamics (in their extended Lagrangian form), as well as driven adiabatic free energy dynamics (dAFED) and unified free energy dynamics (UFED), can be used in combination with any of the three above-mentioned FES estimators. We compare the convergence properties of these estimators on the alanine dipeptide and a sodium ion solvation shell. We find that the mean force estimator is superior in all cases. We also show that it can be marginally beneficial to combine information from the histogram and the force, provided that both are of comparable accuracy.

Data, exergy, and energy analysis of a vertical-bore, ground-source heat pump to for domestic water heating under simulated occupancy conditions

DOE PAGES

Ally, Moonis Raza; Munk, Jeffrey D.; Baxter, Van D.; ...

2015-05-27

Evidence is provided to support the view that greater than two-thirds of energy required to produce domestic hot water may be extracted from the ground which serves as renewable energy resource. The case refers to a 345 m2 research house located in Oak Ridge, Tennessee, 36.01 N 84.26 W in a mixed-humid climate with HDD of 2218 C-days (3993 F-days) and CDD of 723 C-days (1301 F-days). The house is operated under simulated occupancy conditions in which the hot water use protocol is based on the Building America Research Benchmark Definition (Hendron 2008; Hendron and Engebrecht 2010) which captures themore » water consumption lifestyles of the average family in the United States. The 5.275 (1.5-ton) water-to-water ground source heat pump (WW-GSHP) shared the same vertical bore with a 7.56 KW water-to-air ground source heat pump for space conditioning the same house. Energy and exergy analysis of data collected continuously over a twelve month period provide performance metrics and sources of inherent systemic inefficiencies. Data and analyses are vital to better understand how WW-GSHPs may be further improved to enable the ground to be used as a renewable energy resource.« less

Feasibility of generating quantitative composition images in dual energy mammography: a simulation study

NASA Astrophysics Data System (ADS)

Lee, Donghoon; Kim, Ye-seul; Choi, Sunghoon; Lee, Haenghwa; Choi, Seungyeon; Kim, Hee-Joung

2016-03-01

Breast cancer is one of the most common malignancies in women. For years, mammography has been used as the gold standard for localizing breast cancer, despite its limitation in determining cancer composition. Therefore, the purpose of this simulation study is to confirm the feasibility of obtaining tumor composition using dual energy digital mammography. To generate X-ray sources for dual energy mammography, 26 kVp and 39 kVp voltages were generated for low and high energy beams, respectively. Additionally, the energy subtraction and inverse mapping functions were applied to provide compositional images. The resultant images showed that the breast composition obtained by the inverse mapping function with cubic fitting achieved the highest accuracy and least noise. Furthermore, breast density analysis with cubic fitting showed less than 10% error compare to true values. In conclusion, this study demonstrated the feasibility of creating individual compositional images and capability of analyzing breast density effectively.

Scenario simulation based assessment of subsurface energy storage

NASA Astrophysics Data System (ADS)

Beyer, C.; Bauer, S.; Dahmke, A.

2014-12-01

Energy production from renewable sources such as solar or wind power is characterized by temporally varying power supply. The politically intended transition towards renewable energies in Germany („Energiewende") hence requires the installation of energy storage technologies to compensate for the fluctuating production. In this context, subsurface energy storage represents a viable option due to large potential storage capacities and the wide prevalence of suited geological formations. Technologies for subsurface energy storage comprise cavern or deep porous media storage of synthetic hydrogen or methane from electrolysis and methanization, or compressed air, as well as heat storage in shallow or moderately deep porous formations. Pressure build-up, fluid displacement or temperature changes induced by such operations may affect local and regional groundwater flow, geomechanical behavior, groundwater geochemistry and microbiology. Moreover, subsurface energy storage may interact and possibly be in conflict with other "uses" like drinking water abstraction or ecological goods and functions. An utilization of the subsurface for energy storage therefore requires an adequate system and process understanding for the evaluation and assessment of possible impacts of specific storage operations on other types of subsurface use, the affected environment and protected entities. This contribution presents the framework of the ANGUS+ project, in which tools and methods are developed for these types of assessments. Synthetic but still realistic scenarios of geological energy storage are derived and parameterized for representative North German storage sites by data acquisition and evaluation, and experimental work. Coupled numerical hydraulic, thermal, mechanical and reactive transport (THMC) simulation tools are developed and applied to simulate the energy storage and subsurface usage scenarios, which are analyzed for an assessment and generalization of the imposed THMC

Modeling and simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

1986-01-01

This book presents the papers given at a conference on computerized simulation. Topics considered at the conference included expert systems, modeling in electric power systems, power systems operating strategies, energy analysis, a linear programming approach to optimum load shedding in transmission systems, econometrics, simulation in natural gas engineering, solar energy studies, artificial intelligence, vision systems, hydrology, multiprocessors, and flow models.

The effect of binding energy and resolution in simulations of the common envelope binary interaction

NASA Astrophysics Data System (ADS)

Iaconi, Roberto; De Marco, Orsola; Passy, Jean-Claude; Staff, Jan

2018-06-01

The common envelope binary interaction remains one of the least understood phases in the evolution of compact binaries, including those that result in Type Ia supernovae and in mergers that emit detectable gravitational waves. In this work, we continue the detailed and systematic analysis of 3D hydrodynamic simulations of the common envelope interaction aimed at understanding the reliability of the results. Our first set of simulations replicate the five simulations of Passy et al. (a 0.88 M⊙, 90 R⊙ red giant branch (RGB) primary with companions in the range 0.1-0.9 M⊙) using a new adaptive mesh refinement gravity solver implemented on our modified version of the hydrodynamic code ENZO. Despite smaller final separations obtained, these more resolved simulations do not alter the nature of the conclusions that are drawn. We also carry out five identical simulations but with a 2.0 M⊙ primary RGB star with the same core mass as the Passy et al. simulations, isolating the effect of the envelope binding energy. With a more bound envelope, all the companions in-spiral faster and deeper, though relatively less gas is unbound. Even at the highest resolution, the final separation attained by simulations with a heavier primary is similar to the size of the smoothed potential even if we account for the loss of some angular momentum by the simulation. As a result, we suggest that an ˜2.0 M⊙ RGB primary may possibly end in a merger with companions as massive as 0.6 M⊙, something that would not be deduced using analytical arguments based on energy conservation.

Simulating electron energy loss spectroscopy with the MNPBEM toolbox

NASA Astrophysics Data System (ADS)

Hohenester, Ulrich

2014-03-01

Within the MNPBEM toolbox, we show how to simulate electron energy loss spectroscopy (EELS) of plasmonic nanoparticles using a boundary element method approach. The methodology underlying our approach closely follows the concepts developed by García de Abajo and coworkers (Garcia de Abajo, 2010). We introduce two classes eelsret and eelsstat that allow in combination with our recently developed MNPBEM toolbox for a simple, robust, and efficient computation of EEL spectra and maps. The classes are accompanied by a number of demo programs for EELS simulation of metallic nanospheres, nanodisks, and nanotriangles, and for electron trajectories passing by or penetrating through the metallic nanoparticles. We also discuss how to compute electric fields induced by the electron beam and cathodoluminescence. Catalogue identifier: AEKJ_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKJ_v2_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 38886 No. of bytes in distributed program, including test data, etc.: 1222650 Distribution format: tar.gz Programming language: Matlab 7.11.0 (R2010b). Computer: Any which supports Matlab 7.11.0 (R2010b). Operating system: Any which supports Matlab 7.11.0 (R2010b). RAM:≥1 GB Classification: 18. Catalogue identifier of previous version: AEKJ_v1_0 Journal reference of previous version: Comput. Phys. Comm. 183 (2012) 370 External routines: MESH2D available at www.mathworks.com Does the new version supersede the previous version?: Yes Nature of problem: Simulation of electron energy loss spectroscopy (EELS) for plasmonic nanoparticles. Solution method: Boundary element method using electromagnetic potentials. Reasons for new version: The new version of the toolbox includes two additional classes for the simulation of electron energy

Computer simulation program for medium-energy ion scattering and Rutherford backscattering spectrometry

NASA Astrophysics Data System (ADS)

Nishimura, Tomoaki

2016-03-01

A computer simulation program for ion scattering and its graphical user interface (MEISwin) has been developed. Using this program, researchers have analyzed medium-energy ion scattering and Rutherford backscattering spectrometry at Ritsumeikan University since 1998, and at Rutgers University since 2007. The main features of the program are as follows: (1) stopping power can be chosen from five datasets spanning several decades (from 1977 to 2011), (2) straggling can be chosen from two datasets, (3) spectral shape can be selected as Gaussian or exponentially modified Gaussian, (4) scattering cross sections can be selected as Coulomb or screened, (5) simulations adopt the resonant elastic scattering cross section of 16O(4He, 4He)16O, (6) pileup simulation for RBS spectra is supported, (7) natural and specific isotope abundances are supported, and (8) the charge fraction can be chosen from three patterns (fixed, energy-dependent, and ion fraction with charge-exchange parameters for medium-energy ion scattering). This study demonstrates and discusses the simulations and their results.

Coupling the Multizone Airflow and Contaminant Transport Software CONTAM with EnergyPlus Using Co-Simulation.

PubMed

Dols, W Stuart; Emmerich, Steven J; Polidoro, Brian J

2016-08-01

Building modelers need simulation tools capable of simultaneously considering building energy use, airflow and indoor air quality (IAQ) to design and evaluate the ability of buildings and their systems to meet today's demanding energy efficiency and IAQ performance requirements. CONTAM is a widely-used multizone building airflow and contaminant transport simulation tool that requires indoor temperatures as input values. EnergyPlus is a prominent whole-building energy simulation program capable of performing heat transfer calculations that require interzone and infiltration airflows as input values. On their own, each tool is limited in its ability to account for thermal processes upon which building airflow may be significantly dependent and vice versa. This paper describes the initial phase of coupling of CONTAM with EnergyPlus to capture the interdependencies between airflow and heat transfer using co-simulation that allows for sharing of data between independently executing simulation tools. The coupling is accomplished based on the Functional Mock-up Interface (FMI) for Co-simulation specification that provides for integration between independently developed tools. A three-zone combined heat transfer/airflow analytical BESTEST case was simulated to verify the co-simulation is functioning as expected, and an investigation of a two-zone, natural ventilation case designed to challenge the coupled thermal/airflow solution methods was performed.

Energy deposition evaluation for ultra-low energy electron beam irradiation systems using calibrated thin radiochromic film and Monte Carlo simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsui, S., E-mail: smatsui@gpi.ac.jp; Mori, Y.; Nonaka, T.

2016-05-15

For evaluation of on-site dosimetry and process design in industrial use of ultra-low energy electron beam (ULEB) processes, we evaluate the energy deposition using a thin radiochromic film and a Monte Carlo simulation. The response of film dosimeter was calibrated using a high energy electron beam with an acceleration voltage of 2 MV and alanine dosimeters with uncertainty of 11% at coverage factor 2. Using this response function, the results of absorbed dose measurements for ULEB were evaluated from 10 kGy to 100 kGy as a relative dose. The deviation between the responses of deposit energy on the films andmore » Monte Carlo simulations was within 15%. As far as this limitation, relative dose estimation using thin film dosimeters with response function obtained by high energy electron irradiation and simulation results is effective for ULEB irradiation processes management.« less

Coarse-grained simulations of protein-protein association: an energy landscape perspective.

PubMed

Ravikumar, Krishnakumar M; Huang, Wei; Yang, Sichun

2012-08-22

Understanding protein-protein association is crucial in revealing the molecular basis of many biological processes. Here, we describe a theoretical simulation pipeline to study protein-protein association from an energy landscape perspective. First, a coarse-grained model is implemented and its applications are demonstrated via molecular dynamics simulations for several protein complexes. Second, an enhanced search method is used to efficiently sample a broad range of protein conformations. Third, multiple conformations are identified and clustered from simulation data and further projected on a three-dimensional globe specifying protein orientations and interacting energies. Results from several complexes indicate that the crystal-like conformation is favorable on the energy landscape even if the landscape is relatively rugged with metastable conformations. A closer examination on molecular forces shows that the formation of associated protein complexes can be primarily electrostatics-driven, hydrophobics-driven, or a combination of both in stabilizing specific binding interfaces. Taken together, these results suggest that the coarse-grained simulations and analyses provide an alternative toolset to study protein-protein association occurring in functional biomolecular complexes. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Dark Energy Survey Year 1 Results: Multi-Probe Methodology and Simulated Likelihood Analyses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krause, E.; et al.

We present the methodology for and detail the implementation of the Dark Energy Survey (DES) 3x2pt DES Year 1 (Y1) analysis, which combines configuration-space two-point statistics from three different cosmological probes: cosmic shear, galaxy-galaxy lensing, and galaxy clustering, using data from the first year of DES observations. We have developed two independent modeling pipelines and describe the code validation process. We derive expressions for analytical real-space multi-probe covariances, and describe their validation with numerical simulations. We stress-test the inference pipelines in simulated likelihood analyses that vary 6-7 cosmology parameters plus 20 nuisance parameters and precisely resemble the analysis to be presented in the DES 3x2pt analysis paper, using a variety of simulated input data vectors with varying assumptions. We find that any disagreement between pipelines leads to changes in assigned likelihoodmore » $$\\Delta \\chi^2 \\le 0.045$$ with respect to the statistical error of the DES Y1 data vector. We also find that angular binning and survey mask do not impact our analytic covariance at a significant level. We determine lower bounds on scales used for analysis of galaxy clustering (8 Mpc$$~h^{-1}$$) and galaxy-galaxy lensing (12 Mpc$$~h^{-1}$$) such that the impact of modeling uncertainties in the non-linear regime is well below statistical errors, and show that our analysis choices are robust against a variety of systematics. These tests demonstrate that we have a robust analysis pipeline that yields unbiased cosmological parameter inferences for the flagship 3x2pt DES Y1 analysis. We emphasize that the level of independent code development and subsequent code comparison as demonstrated in this paper is necessary to produce credible constraints from increasingly complex multi-probe analyses of current data.« less

Commercial Building Energy Saver, API

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, Tianzhen; Piette, Mary; Lee, Sang Hoon

2015-08-27

The CBES API provides Application Programming Interface to a suite of functions to improve energy efficiency of buildings, including building energy benchmarking, preliminary retrofit analysis using a pre-simulation database DEEP, and detailed retrofit analysis using energy modeling with the EnergyPlus simulation engine. The CBES API is used to power the LBNL CBES Web App. It can be adopted by third party developers and vendors into their software tools and platforms.

Validation Methodology to Allow Simulated Peak Reduction and Energy Performance Analysis of Residential Building Envelope with Phase Change Materials: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tabares-Velasco, P. C.; Christensen, C.; Bianchi, M.

2012-08-01

Phase change materials (PCM) represent a potential technology to reduce peak loads and HVAC energy consumption in residential buildings. This paper summarizes NREL efforts to obtain accurate energy simulations when PCMs are modeled in residential buildings: the overall methodology to verify and validate Conduction Finite Difference (CondFD) and PCM algorithms in EnergyPlus is presented in this study. It also shows preliminary results of three residential building enclosure technologies containing PCM: PCM-enhanced insulation, PCM impregnated drywall and thin PCM layers. The results are compared based on predicted peak reduction and energy savings using two algorithms in EnergyPlus: the PCM and Conductionmore » Finite Difference (CondFD) algorithms.« less

Analysis of Plane-Parallel Electron Beam Propagation in Different Media by Numerical Simulation Methods

NASA Astrophysics Data System (ADS)

Miloichikova, I. A.; Bespalov, V. I.; Krasnykh, A. A.; Stuchebrov, S. G.; Cherepennikov, Yu. M.; Dusaev, R. R.

2018-04-01

Simulation by the Monte Carlo method is widely used to calculate the character of ionizing radiation interaction with substance. A wide variety of programs based on the given method allows users to choose the most suitable package for solving computational problems. In turn, it is important to know exactly restrictions of numerical systems to avoid gross errors. Results of estimation of the feasibility of application of the program PCLab (Computer Laboratory, version 9.9) for numerical simulation of the electron energy distribution absorbed in beryllium, aluminum, gold, and water for industrial, research, and clinical beams are presented. The data obtained using programs ITS and Geant4 being the most popular software packages for solving the given problems and the program PCLab are presented in the graphic form. A comparison and an analysis of the results obtained demonstrate the feasibility of application of the program PCLab for simulation of the absorbed energy distribution and dose of electrons in various materials for energies in the range 1-20 MeV.

Irregular Wave Energy Extraction Analysis for a Slider Crank WEC Power Take-Off System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sang, Yuanrui; Karayaka, H. Bora; Yan, Yanjun

2015-09-02

Slider crank Wave Energy Converter (WEC) is a novel energy conversion device. It converts wave energy into electricity at a relatively high efficiency, and it features a simple structure. Past analysis on this WEC has been done under regular sinusoidal wave conditions, and a suboptimal energy could be achieved. This paper presents the analysis of the system under irregular wave conditions; a time-domain hydrodynamics model is adopted and the control methodology is modified to better serve the irregular wave conditions. Results from the simulations show that the performance of the system under irregular wave conditions is different from that undermore » regular sinusoidal wave conditions, but still a reasonable amount of energy can be extracted.« less

Holistic Nursing Simulation: A Concept Analysis.

PubMed

Cohen, Bonni S; Boni, Rebecca

2018-03-01

Simulation as a technology and holistic nursing care as a philosophy are two components within nursing programs that have merged during the process of knowledge and skill acquisition in the care of the patients as whole beings. Simulation provides opportunities to apply knowledge and skill through the use of simulators, standardized patients, and virtual settings. Concerns with simulation have been raised regarding the integration of the nursing process and recognizing the totality of the human being. Though simulation is useful as a technology, the nursing profession places importance on patient care, drawing on knowledge, theories, and expertise to administer patient care. There is a need to promptly and comprehensively define the concept of holistic nursing simulation to provide consistency and a basis for quality application within nursing curricula. This concept analysis uses Walker and Avant's approach to define holistic nursing simulation by defining antecedents, consequences, and empirical referents. The concept of holism and the practice of holistic nursing incorporated into simulation require an analysis of the concept of holistic nursing simulation by developing a language and model to provide direction for educators in design and development of holistic nursing simulation.

Use of a grid simulation model for longer-term analysis of wind energy integration

NASA Astrophysics Data System (ADS)

Bossanyi, E.

A simulation model of an electricity generating system is used to study the integration of wind energy onto the system. Most of the system cost savings achieved are due to the savings of fossil fuels, but in the long term additional savings result from re-optimization of the plant mix. Break-even costs are calculated for wind turbines to become economically viable as fossil fuel savers. This allows the optimum economic penetration level for wind turbines of any given cost to be derived. Break-even costs up to reasonably large penetrations appear to be within reach with modern technology. Results are also given with scenarios of increasing fossil fuel prices and increased nuclear capacity.

Simulation and Fabrication of Wagon-Wheel-Shaped Piezoelectric Transducer for Raindrop Energy Harvesting Application

NASA Astrophysics Data System (ADS)

Wong, Chin Hong; Dahari, Zuraini; Jumali, Mohammad Hafizuddin; Mohamed, Khairudin; Mohamed, Julie Juliewatty

2017-03-01

Harvesting vibrational energy from impacting raindrops using piezoelectric material has been proven to be a promising approach for future outdoor applications, providing a good alternative resource that can be applied in outdoor rainy environments. We present herein an optimum novel polyvinylidene fluoride (PVDF) piezoelectric transducer specifically developed to harvest raindrop energy. The finite-element method was applied for simulation and optimization of the piezoelectric raindrop energy harvester (PREH) using COMSOL Multiphysics software, investigating the electrical potential, surface charge density, and total displacement for different transducer dimensions. According to the simulation results, the structure that generated the highest electrical potential and surface charge density was a wagon-wheel-shaped structure consisting of six spokes with wheel diameter of 30 mm, spoke width of 2 mm, center pad diameter of 6 mm, and thickness of 25 μm. This optimum wagon-wheel-shaped device was then fabricated by spin coating of PVDF, sputtering of aluminum, a poling process, and computer numerical control machining of a polytetrafluoroethylene stand. The fabricated PREH was characterized by x-ray diffraction analysis and Fourier-transform infrared spectroscopy. Finally, the fabricated PREH was tested under actual rain conditions with an alternating current to direct current converter connected in parallel, revealing that a single cell could generate average peak voltage of 22.5 mV and produce electrical energy of 3.4 nJ from ten impacts in 20 s.

NISAC | National Infrastructure Simulation and Analysis Center | NISAC

Science.gov Websites

Logo National Infrastructure Simulation and Analysis Center Search Btn search this site... Overview Capabilities Fact Sheets Publications Contacts NISAC content top NISAC The National Infrastructure Simulation and Analysis Center (NISAC) is a modeling, simulation, and analysis program within the Department of

Thermal and Mechanical Non-Equilibrium Effects on Turbulent Flows: Fundamental Studies of Energy Exchanges Through Direct Numerical Simulations, Molecular Simulations and Experiments

DTIC Science & Technology

2016-02-26

AFRL-AFOSR-VA-TR-2016-0104 Thermal and mechanical non-equilibrium effects on turbulent flows:fundamental studies of energy exchanges through direct...flows: fundamental studies of energy exchanges through direct numerical simulations, molecular simulations and experiments 5a.  CONTRACT NUMBER 5b...AVAILABILITY STATEMENT A DISTRIBUTION UNLIMITED: PB Public Release 13. SUPPLEMENTARY NOTES 14. ABSTRACT Utilizing internal energy exchange for intelligent

Extracting Aggregation Free Energies of Mixed Clusters from Simulations of Small Systems: Application to Ionic Surfactant Micelles.

PubMed

Zhang, X; Patel, L A; Beckwith, O; Schneider, R; Weeden, C J; Kindt, J T

2017-11-14

Micelle cluster distributions from molecular dynamics simulations of a solvent-free coarse-grained model of sodium octyl sulfate (SOS) were analyzed using an improved method to extract equilibrium association constants from small-system simulations containing one or two micelle clusters at equilibrium with free surfactants and counterions. The statistical-thermodynamic and mathematical foundations of this partition-enabled analysis of cluster histograms (PEACH) approach are presented. A dramatic reduction in computational time for analysis was achieved through a strategy similar to the selector variable method to circumvent the need for exhaustive enumeration of the possible partitions of surfactants and counterions into clusters. Using statistics from a set of small-system (up to 60 SOS molecules) simulations as input, equilibrium association constants for micelle clusters were obtained as a function of both number of surfactants and number of associated counterions through a global fitting procedure. The resulting free energies were able to accurately predict micelle size and charge distributions in a large (560 molecule) system. The evolution of micelle size and charge with SOS concentration as predicted by the PEACH-derived free energies and by a phenomenological four-parameter model fit, along with the sensitivity of these predictions to variations in cluster definitions, are analyzed and discussed.

Zero-point energy conservation in classical trajectory simulations: Application to H2CO

NASA Astrophysics Data System (ADS)

Lee, Kin Long Kelvin; Quinn, Mitchell S.; Kolmann, Stephen J.; Kable, Scott H.; Jordan, Meredith J. T.

2018-05-01

A new approach for preventing zero-point energy (ZPE) violation in quasi-classical trajectory (QCT) simulations is presented and applied to H2CO "roaming" reactions. Zero-point energy may be problematic in roaming reactions because they occur at or near bond dissociation thresholds and these channels may be incorrectly open or closed depending on if, or how, ZPE has been treated. Here we run QCT simulations on a "ZPE-corrected" potential energy surface defined as the sum of the molecular potential energy surface (PES) and the global harmonic ZPE surface. Five different harmonic ZPE estimates are examined with four, on average, giving values within 4 kJ/mol—chemical accuracy—for H2CO. The local harmonic ZPE, at arbitrary molecular configurations, is subsequently defined in terms of "projected" Cartesian coordinates and a global ZPE "surface" is constructed using Shepard interpolation. This, combined with a second-order modified Shepard interpolated PES, V, allows us to construct a proof-of-concept ZPE-corrected PES for H2CO, Veff, at no additional computational cost to the PES itself. Both V and Veff are used to model product state distributions from the H + HCO → H2 + CO abstraction reaction, which are shown to reproduce the literature roaming product state distributions. Our ZPE-corrected PES allows all trajectories to be analysed, whereas, in previous simulations, a significant proportion was discarded because of ZPE violation. We find ZPE has little effect on product rotational distributions, validating previous QCT simulations. Running trajectories on V, however, shifts the product kinetic energy release to higher energy than on Veff and classical simulations of kinetic energy release should therefore be viewed with caution.

Automated detection and analysis of particle beams in laser-plasma accelerator simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ushizima, Daniela Mayumi; Geddes, C.G.; Cormier-Michel, E.

Numerical simulations of laser-plasma wakefield (particle) accelerators model the acceleration of electrons trapped in plasma oscillations (wakes) left behind when an intense laser pulse propagates through the plasma. The goal of these simulations is to better understand the process involved in plasma wake generation and how electrons are trapped and accelerated by the wake. Understanding of such accelerators, and their development, offer high accelerating gradients, potentially reducing size and cost of new accelerators. One operating regime of interest is where a trapped subset of electrons loads the wake and forms an isolated group of accelerated particles with low spread inmore » momentum and position, desirable characteristics for many applications. The electrons trapped in the wake may be accelerated to high energies, the plasma gradient in the wake reaching up to a gigaelectronvolt per centimeter. High-energy electron accelerators power intense X-ray radiation to terahertz sources, and are used in many applications including medical radiotherapy and imaging. To extract information from the simulation about the quality of the beam, a typical approach is to examine plots of the entire dataset, visually determining the adequate parameters necessary to select a subset of particles, which is then further analyzed. This procedure requires laborious examination of massive data sets over many time steps using several plots, a routine that is unfeasible for large data collections. Demand for automated analysis is growing along with the volume and size of simulations. Current 2D LWFA simulation datasets are typically between 1GB and 100GB in size, but simulations in 3D are of the order of TBs. The increase in the number of datasets and dataset sizes leads to a need for automatic routines to recognize particle patterns as particle bunches (beam of electrons) for subsequent analysis. Because of the growth in dataset size, the application of machine learning techniques

Random walk numerical simulation for hopping transport at finite carrier concentrations: diffusion coefficient and transport energy concept.

PubMed

Gonzalez-Vazquez, J P; Anta, Juan A; Bisquert, Juan

2009-11-28

The random walk numerical simulation (RWNS) method is used to compute diffusion coefficients for hopping transport in a fully disordered medium at finite carrier concentrations. We use Miller-Abrahams jumping rates and an exponential distribution of energies to compute the hopping times in the random walk simulation. The computed diffusion coefficient shows an exponential dependence with respect to Fermi-level and Arrhenius behavior with respect to temperature. This result indicates that there is a well-defined transport level implicit to the system dynamics. To establish the origin of this transport level we construct histograms to monitor the energies of the most visited sites. In addition, we construct "corrected" histograms where backward moves are removed. Since these moves do not contribute to transport, these histograms provide a better estimation of the effective transport level energy. The analysis of this concept in connection with the Fermi-level dependence of the diffusion coefficient and the regime of interest for the functioning of dye-sensitised solar cells is thoroughly discussed.

Quantifying the Energy Landscape Statistics in Proteins - a Relaxation Mode Analysis

NASA Astrophysics Data System (ADS)

Cai, Zhikun; Zhang, Yang

Energy landscape, the hypersurface in the configurational space, has been a useful concept in describing complex processes that occur over a very long time scale, such as the multistep slow relaxations of supercooled liquids and folding of polypeptide chains into structured proteins. Despite extensive simulation studies, its experimental characterization still remains a challenge. To address this challenge, we developed a relaxation mode analysis (RMA) for liquids under a framework analogous to the normal mode analysis for solids. Using RMA, important statistics of the activation barriers of the energy landscape becomes accessible from experimentally measurable two-point correlation functions, e.g. using quasi-elastic and inelastic scattering experiments. We observed a prominent coarsening effect of the energy landscape. The results were further confirmed by direct sampling of the energy landscape using a metadynamics-like adaptive autonomous basin climbing computation. We first demonstrate RMA in a supercooled liquid when dynamical cooperativity emerges in the landscape-influenced regime. Then we show this framework reveals encouraging energy landscape statistics when applied to proteins.

Quantitative assessment of energy and resource recovery in wastewater treatment plants based on plant-wide simulations.

PubMed

Fernández-Arévalo, T; Lizarralde, I; Fdz-Polanco, F; Pérez-Elvira, S I; Garrido, J M; Puig, S; Poch, M; Grau, P; Ayesa, E

2017-07-01

The growing development of technologies and processes for resource treatment and recovery is offering endless possibilities for creating new plant-wide configurations or modifying existing ones. However, the configurations' complexity, the interrelation between technologies and the influent characteristics turn decision-making into a complex or unobvious process. In this frame, the Plant-Wide Modelling (PWM) library presented in this paper allows a thorough, comprehensive and refined analysis of different plant configurations that are basic aspects in decision-making from an energy and resource recovery perspective. In order to demonstrate the potential of the library and the need to run simulation analyses, this paper carries out a comparative analysis of WWTPs, from a techno-economic point of view. The selected layouts were (1) a conventional WWTP based on a modified version of the Benchmark Simulation Model No. 2, (2) an upgraded or retrofitted WWTP, and (3) a new Wastewater Resource Recovery Facilities (WRRF) concept denominated as C/N/P decoupling WWTP. The study was based on a preliminary analysis of the organic matter and nutrient energy use and recovery options, a comprehensive mass and energy flux distribution analysis in each configuration in order to compare and identify areas for improvement, and a cost analysis of each plant for different influent COD/TN/TP ratios. Analysing the plants from a standpoint of resources and energy utilization, a low utilization of the energy content of the components could be observed in all configurations. In the conventional plant, the COD used to produce biogas was around 29%, the upgraded plant was around 36%, and 34% in the C/N/P decoupling WWTP. With regard to the self-sufficiency of plants, achieving self-sufficiency was not possible in the conventional plant, in the upgraded plant it depended on the influent C/N ratio, and in the C/N/P decoupling WWTP layout self-sufficiency was feasible for almost all influents

Full long-term design response analysis of a wave energy converter

DOE PAGES

Coe, Ryan G.; Michelen, Carlos; Eckert-Gallup, Aubrey; ...

2017-09-21

Efficient design of wave energy converters requires an accurate understanding of expected loads and responses during the deployment lifetime of a device. A study has been conducted to better understand best-practices for prediction of design responses in a wave energy converter. A case-study was performed in which a simplified wave energy converter was analyzed to predict several important device design responses. The application and performance of a full long-term analysis, in which numerical simulations were used to predict the device response for a large number of distinct sea states, was studied. Environmental characterization and selection of sea states for thismore » analysis at the intended deployment site were performed using principle-components analysis. The full long-term analysis applied here was shown to be stable when implemented with a relatively low number of sea states and convergent with an increasing number of sea states. As the number of sea states utilized in the analysis was increased, predicted response levels did not change appreciably. Furthermore, uncertainty in the response levels was reduced as more sea states were utilized.« less

Full long-term design response analysis of a wave energy converter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coe, Ryan G.; Michelen, Carlos; Eckert-Gallup, Aubrey

Efficient design of wave energy converters requires an accurate understanding of expected loads and responses during the deployment lifetime of a device. A study has been conducted to better understand best-practices for prediction of design responses in a wave energy converter. A case-study was performed in which a simplified wave energy converter was analyzed to predict several important device design responses. The application and performance of a full long-term analysis, in which numerical simulations were used to predict the device response for a large number of distinct sea states, was studied. Environmental characterization and selection of sea states for thismore » analysis at the intended deployment site were performed using principle-components analysis. The full long-term analysis applied here was shown to be stable when implemented with a relatively low number of sea states and convergent with an increasing number of sea states. As the number of sea states utilized in the analysis was increased, predicted response levels did not change appreciably. Furthermore, uncertainty in the response levels was reduced as more sea states were utilized.« less

Linking Automated Data Analysis and Visualization with Applications in Developmental Biology and High-Energy Physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruebel, Oliver

2009-11-20

Knowledge discovery from large and complex collections of today's scientific datasets is a challenging task. With the ability to measure and simulate more processes at increasingly finer spatial and temporal scales, the increasing number of data dimensions and data objects is presenting tremendous challenges for data analysis and effective data exploration methods and tools. Researchers are overwhelmed with data and standard tools are often insufficient to enable effective data analysis and knowledge discovery. The main objective of this thesis is to provide important new capabilities to accelerate scientific knowledge discovery form large, complex, and multivariate scientific data. The research coveredmore » in this thesis addresses these scientific challenges using a combination of scientific visualization, information visualization, automated data analysis, and other enabling technologies, such as efficient data management. The effectiveness of the proposed analysis methods is demonstrated via applications in two distinct scientific research fields, namely developmental biology and high-energy physics.Advances in microscopy, image analysis, and embryo registration enable for the first time measurement of gene expression at cellular resolution for entire organisms. Analysis of high-dimensional spatial gene expression datasets is a challenging task. By integrating data clustering and visualization, analysis of complex, time-varying, spatial gene expression patterns and their formation becomes possible. The analysis framework MATLAB and the visualization have been integrated, making advanced analysis tools accessible to biologist and enabling bioinformatic researchers to directly integrate their analysis with the visualization. Laser wakefield particle accelerators (LWFAs) promise to be a new compact source of high-energy particles and radiation, with wide applications ranging from medicine to physics. To gain insight into the complex physical processes of

Filtering analysis of a direct numerical simulation of the turbulent Rayleigh-Benard problem

NASA Technical Reports Server (NTRS)

Eidson, T. M.; Hussaini, M. Y.; Zang, T. A.

1990-01-01

A filtering analysis of a turbulent flow was developed which provides details of the path of the kinetic energy of the flow from its creation via thermal production to its dissipation. A low-pass spatial filter is used to split the velocity and the temperature field into a filtered component (composed mainly of scales larger than a specific size, nominally the filter width) and a fluctuation component (scales smaller than a specific size). Variables derived from these fields can fall into one of the above two ranges or be composed of a mixture of scales dominated by scales near the specific size. The filter is used to split the kinetic energy equation into three equations corresponding to the three scale ranges described above. The data from a direct simulation of the Rayleigh-Benard problem for conditions where the flow is turbulent are used to calculate the individual terms in the three kinetic energy equations. This is done for a range of filter widths. These results are used to study the spatial location and the scale range of the thermal energy production, the cascading of kinetic energy, the diffusion of kinetic energy, and the energy dissipation. These results are used to evaluate two subgrid models typically used in large-eddy simulations of turbulence. Subgrid models attempt to model the energy below the filter width that is removed by a low-pass filter.

Low-Energy Impacts onto Lunar Regolith Simulant

NASA Astrophysics Data System (ADS)

Seward, Laura M.; Colwell, J.; Mellon, M.; Stemm, B.

2012-10-01

Low-Energy Impacts onto Lunar Regolith Simulant Laura M. Seward1, Joshua E. Colwell1, Michael T. Mellon2, and Bradley A. Stemm1, 1Department of Physics, University of Central Florida, Orlando, Florida, 2Southwest Research Institute, Boulder, Colorado. Impacts and cratering in space play important roles in the formation and evolution of planetary bodies. Low-velocity impacts and disturbances to planetary regolith are also a consequence of manned and robotic exploration of planetary bodies such as the Moon, Mars, and asteroids. We are conducting a program of laboratory experiments to study low-velocity impacts of 1 to 5 m/s into JSC-1 lunar regolith simulant, JSC-Mars-1 Martian regolith simulant, and silica targets under 1 g. We use direct measurement of ejecta mass and high-resolution video tracking of ejecta particle trajectories to derive ejecta mass velocity distributions. Additionally, we conduct similar experiments under microgravity conditions in a laboratory drop tower and on parabolic aircraft with velocities as low as 10 cm/s. We wish to characterize and understand the collision parameters that control the outcome of low-velocity impacts into regolith, including impact velocity, impactor mass, target shape and size distribution, regolith depth, target relative density, and crater depth, and to experimentally determine the functional dependencies of the outcomes of low-velocity collisions (ejecta mass and ejecta velocities) on the controlling parameters of the collision. We present results from our ongoing study showing the positive correlation between impact energy and ejecta mass. The total ejecta mass is also dependent on the packing density (porosity) of the regolith. We find that ejecta mass velocity fits a power-law or broken power-law distribution. Our goal is to understand the physics of ejecta production and regolith compaction in low-energy impacts and experimentally validate predictive models for dust flow and deposition. We will present our

Coupling Visualization, Simulation, and Deep Learning for Ensemble Steering of Complex Energy Models: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Potter, Kristin C; Brunhart-Lupo, Nicholas J; Bush, Brian W

We have developed a framework for the exploration, design, and planning of energy systems that combines interactive visualization with machine-learning based approximations of simulations through a general purpose dataflow API. Our system provides a visual inter- face allowing users to explore an ensemble of energy simulations representing a subset of the complex input parameter space, and spawn new simulations to 'fill in' input regions corresponding to new enegery system scenarios. Unfortunately, many energy simula- tions are far too slow to provide interactive responses. To support interactive feedback, we are developing reduced-form models via machine learning techniques, which provide statistically soundmore » esti- mates of the full simulations at a fraction of the computational cost and which are used as proxies for the full-form models. Fast com- putation and an agile dataflow enhance the engagement with energy simulations, and allow researchers to better allocate computational resources to capture informative relationships within the system and provide a low-cost method for validating and quality-checking large-scale modeling efforts.« less

Analysis of energy flow during playground surface impacts.

PubMed

Davidson, Peter L; Wilson, Suzanne J; Chalmers, David J; Wilson, Barry D; Eager, David; McIntosh, Andrew S

2013-10-01

The amount of energy dissipated away from or returned to a child falling onto a surface will influence fracture risk but is not considered in current standards for playground impact-attenuating surfaces. A two-mass rheological computer simulation was used to model energy flow within the wrist and surface during hand impact with playground surfaces, and the potential of this approach to provide insights into such impacts and predict injury risk examined. Acceleration data collected on-site from typical playground surfaces and previously obtained data from children performing an exercise involving freefalling with a fully extended arm provided input. The model identified differences in energy flow properties between playground surfaces and two potentially harmful surface characteristics: more energy was absorbed by (work done on) the wrist during both impact and rebound on rubber surfaces than on bark, and rubber surfaces started to rebound (return energy to the wrist) while the upper limb was still moving downward. Energy flow analysis thus provides information on playground surface characteristics and the impact process, and has the potential to identify fracture risks, inform the development of safer impact-attenuating surfaces, and contribute to development of new energy-based arm fracture injury criteria and tests for use in conjunction with current methods.

Dynamic simulation and preliminary finite element analysis of gunshot wounds to the human mandible.

PubMed

Tang, Zhen; Tu, Wenbing; Zhang, Gang; Chen, Yubin; Lei, Tao; Tan, Yinghui

2012-05-01

Due to the complications arising from gunshot wounds to the maxillofacial region, traditional models of gunshot wounds cannot meet our research needs. In this study, we established a finite element model and conducted preliminary simulation and analysis to determine the injury mechanism and degree of damage for gunshot wounds to the human mandible. Based on a previously developed modelling method that used animal experiments and internal parameters, digital computed tomography data for the human mandible were used to establish a three-dimensional finite element model of the human mandible. The mechanism by which a gunshot injures the mandible was dynamically simulated under different shot conditions. First, the residual velocities of the shootings using different projectiles at varying entry angles and impact velocities were calculated. Second, the energy losses of the projectiles and the rates of energy loss after exiting the mandible were calculated. Finally, the data were compared and analysed. The dynamic processes involved in gunshot wounds to the human mandible were successfully simulated using two projectiles, three impact velocities, and three entry angles. The stress distributions in different parts of mandible after injury were also simulated. Based on the computation and analysis of the modelling data, we found that the injury severity of the mandible and the injury efficiency of the projectiles differ under different injury conditions. The finite element model has many advantages for the analysis of ballistic wounds, and is expected to become an improved model for studying maxillofacial gunshot wounds. Copyright © 2011 Elsevier Ltd. All rights reserved.

Simulations of skin barrier function: free energies of hydrophobic and hydrophilic transmembrane pores in ceramide bilayers.

PubMed

Notman, Rebecca; Anwar, Jamshed; Briels, W J; Noro, Massimo G; den Otter, Wouter K

2008-11-15

Transmembrane pore formation is central to many biological processes such as ion transport, cell fusion, and viral infection. Furthermore, pore formation in the ceramide bilayers of the stratum corneum may be an important mechanism by which penetration enhancers such as dimethylsulfoxide (DMSO) weaken the barrier function of the skin. We have used the potential of mean constraint force (PMCF) method to calculate the free energy of pore formation in ceramide bilayers in both the innate gel phase and in the DMSO-induced fluidized state. Our simulations show that the fluid phase bilayers form archetypal water-filled hydrophilic pores similar to those observed in phospholipid bilayers. In contrast, the rigid gel-phase bilayers develop hydrophobic pores. At the relatively small pore diameters studied here, the hydrophobic pores are empty rather than filled with bulk water, suggesting that they do not compromise the barrier function of ceramide membranes. A phenomenological analysis suggests that these vapor pores are stable, below a critical radius, because the penalty of creating water-vapor and tail-vapor interfaces is lower than that of directly exposing the strongly hydrophobic tails to water. The PMCF free energy profile of the vapor pore supports this analysis. The simulations indicate that high DMSO concentrations drastically impair the barrier function of the skin by strongly reducing the free energy required for pore opening.

Simulations of Skin Barrier Function: Free Energies of Hydrophobic and Hydrophilic Transmembrane Pores in Ceramide Bilayers

PubMed Central

Notman, Rebecca; Anwar, Jamshed; Briels, W. J.; Noro, Massimo G.; den Otter, Wouter K.

2008-01-01

Transmembrane pore formation is central to many biological processes such as ion transport, cell fusion, and viral infection. Furthermore, pore formation in the ceramide bilayers of the stratum corneum may be an important mechanism by which penetration enhancers such as dimethylsulfoxide (DMSO) weaken the barrier function of the skin. We have used the potential of mean constraint force (PMCF) method to calculate the free energy of pore formation in ceramide bilayers in both the innate gel phase and in the DMSO-induced fluidized state. Our simulations show that the fluid phase bilayers form archetypal water-filled hydrophilic pores similar to those observed in phospholipid bilayers. In contrast, the rigid gel-phase bilayers develop hydrophobic pores. At the relatively small pore diameters studied here, the hydrophobic pores are empty rather than filled with bulk water, suggesting that they do not compromise the barrier function of ceramide membranes. A phenomenological analysis suggests that these vapor pores are stable, below a critical radius, because the penalty of creating water-vapor and tail-vapor interfaces is lower than that of directly exposing the strongly hydrophobic tails to water. The PMCF free energy profile of the vapor pore supports this analysis. The simulations indicate that high DMSO concentrations drastically impair the barrier function of the skin by strongly reducing the free energy required for pore opening. PMID:18708461

Monte Carlo simulations on atropisomerism of thienotriazolodiazepines applicable to slow transition phenomena using potential energy surfaces by ab initio molecular orbital calculations.

PubMed

Morikami, Kenji; Itezono, Yoshiko; Nishimoto, Masahiro; Ohta, Masateru

2014-01-01

Compounds with a medium-sized flexible ring often show atropisomerism that is caused by the high-energy barriers between long-lived conformers that can be isolated and often have different biological properties to each other. In this study, the frequency of the transition between the two stable conformers, aS and aR, of thienotriazolodiazepine compounds with flexible 7-membered rings was estimated computationally by Monte Carlo (MC) simulations and validated experimentally by NMR experiments. To estimate the energy barriers for transitions as precisely as possible, the potential energy (PE) surfaces used in the MC simulations were calculated by molecular orbital (MO) methods. To accomplish the MC simulations with the MO-based PE surfaces in a practical central processing unit (CPU) time, the MO-based PE of each conformer was pre-calculated and stored before the MC simulations, and then only referred to during the MC simulations. The activation energies for transitions calculated by the MC simulations agreed well with the experimental ΔG determined by the NMR experiments. The analysis of the transition trajectories of the MC simulations revealed that the transition occurred not only through the transition states, but also through many different transition paths. Our computational methods gave us quantitative estimates of atropisomerism of the thienotriazolodiazepine compounds in a practical period of time, and the method could be applicable for other slow-dynamics phenomena that cannot be investigated by other atomistic simulations.

Statistical analysis of CSP plants by simulating extensive meteorological series

NASA Astrophysics Data System (ADS)

Pavón, Manuel; Fernández, Carlos M.; Silva, Manuel; Moreno, Sara; Guisado, María V.; Bernardos, Ana

2017-06-01

The feasibility analysis of any power plant project needs the estimation of the amount of energy it will be able to deliver to the grid during its lifetime. To achieve this, its feasibility study requires a precise knowledge of the solar resource over a long term period. In Concentrating Solar Power projects (CSP), financing institutions typically requires several statistical probability of exceedance scenarios of the expected electric energy output. Currently, the industry assumes a correlation between probabilities of exceedance of annual Direct Normal Irradiance (DNI) and energy yield. In this work, this assumption is tested by the simulation of the energy yield of CSP plants using as input a 34-year series of measured meteorological parameters and solar irradiance. The results of this work show that, even if some correspondence between the probabilities of exceedance of annual DNI values and energy yields is found, the intra-annual distribution of DNI may significantly affect this correlation. This result highlights the need of standardized procedures for the elaboration of representative DNI time series representative of a given probability of exceedance of annual DNI.

Scope of wind energy in Bangladesh and simulation analysis of three different horizontal axis wind turbine blade shapes

NASA Astrophysics Data System (ADS)

Khan, Md. Arif-Ul Islam; Das, Swapnil; Dey, Saikat

2017-12-01

: Economic growth and energy demand are intertwined. Therefore, one of the most important concerns of the government and in the world is the need for energy security. Currently, the world relies on coal, crude oil and natural gas for energy generati on. However, the energy crisis together with climate change and depletion of oil have become major concerns to all countries. Therefore, alternative energy resources such as wind energy attracted interest from both public and private sectors to invest in energy generation from this source extensively. Both Vertical and Horizontal axis wind turbine can be used for this purpose. But, Horizontal axis is the most promising between them due to its efficiency and low expense. Bangladesh being a tropical country does have a lot of wind flow at different seasons of the year. However, there are some windy locations in which wind energy projects could be feasible. In this project a detailed review of the current st ate-of-art for wind turbine blade design is presented including theoretical maximum efficiency, Horizontal Axis Wind Turbine (HAWT) blade design, simulation power and COP values for different blade material. By studying previously collected data on the wind resources available in B angladesh at present and by analyzing this data, this paper will discuss the scope of wind energy in Bangladesh.

The Application of High Energy Resolution Green's Functions to Threat Scenario Simulation

NASA Astrophysics Data System (ADS)

Thoreson, Gregory G.; Schneider, Erich A.

2012-04-01

Radiation detectors installed at key interdiction points provide defense against nuclear smuggling attempts by scanning vehicles and traffic for illicit nuclear material. These hypothetical threat scenarios may be modeled using radiation transport simulations. However, high-fidelity models are computationally intensive. Furthermore, the range of smuggler attributes and detector technologies create a large problem space not easily overcome by brute-force methods. Previous research has demonstrated that decomposing the scenario into independently simulated components using Green's functions can simulate photon detector signals with coarse energy resolution. This paper extends this methodology by presenting physics enhancements and numerical treatments which allow for an arbitrary level of energy resolution for photon transport. As a result, spectroscopic detector signals produced from full forward transport simulations can be replicated while requiring multiple orders of magnitude less computation time.

A Method for Modeling Household Occupant Behavior to Simulate Residential Energy Consumption

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Brandon J; Starke, Michael R; Abdelaziz, Omar

2014-01-01

This paper presents a statistical method for modeling the behavior of household occupants to estimate residential energy consumption. Using data gathered by the U.S. Census Bureau in the American Time Use Survey (ATUS), actions carried out by survey respondents are categorized into ten distinct activities. These activities are defined to correspond to the major energy consuming loads commonly found within the residential sector. Next, time varying minute resolution Markov chain based statistical models of different occupant types are developed. Using these behavioral models, individual occupants are simulated to show how an occupant interacts with the major residential energy consuming loadsmore » throughout the day. From these simulations, the minimum number of occupants, and consequently the minimum number of multiple occupant households, needing to be simulated to produce a statistically accurate representation of aggregate residential behavior can be determined. Finally, future work will involve the use of these occupant models along side residential load models to produce a high-resolution energy consumption profile and estimate the potential for demand response from residential loads.« less

Hybrid Simulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trujillo, David J.; Sridharan, Srikesh; Weinstock, Irvin

HybSim (short for Hybrid Simulator) is a flexible, easy to use screening tool that allows the user to quanti the technical and economic benefits of installing a village hybrid generating system and simulates systems with any combination of —Diesel generator sets —Photovoltaic arrays -Wind Turbines and -Battery energy storage systems Most village systems (or small population sites such as villages, remote military bases, small communities, independent or isolated buildings or centers) depend on diesel generation systems for their source of energy. HybSim allows the user to determine other "sources" of energy that can greatly reduce the dollar to kilo-watt hourmore » ratio. Supported by the DOE, Energy Storage Program, HybSim was initially developed to help analyze the benefits of energy storage systems in Alaskan villages. Soon after its development, other sources of energy were added providing the user with a greater range of analysis opportunities and providing the village with potentially added savings. In addition to village systems, HybSim has generated interest for use from military institutions in energy provisions and USAID for international village analysis.« less

Magneto-acoustic wave energy in sunspots: observations and numerical simulations

NASA Astrophysics Data System (ADS)

Felipe, T.; Khomenko, E.; Collados, M.; Beck, C.

2011-11-01

We have reproduced some sunspot wave signatures obtained from spectropolarimetric observations through 3D MHD numericalsimulations. The results of the simulations arecompared with the oscillations observed simultaneously at different heights from the SiI lambda10827Å line, HeI lambda10830Å line, the CaII H core and the FeI blends at the wings of the CaII H line. The simulations show a remarkable agreement with the observations, and we have used them to quantify the energy contribution of the magneto-acoustic waves to the chromospheric heating in sunspots. Our findings indicate that the energy supplied by these waves is 5-10 times lower than the amount needed to balance the chromospheric radiative losses.

Free energy of solvated salt bridges: a simulation and experimental study.

PubMed

White, Andrew D; Keefe, Andrew J; Ella-Menye, Jean-Rene; Nowinski, Ann K; Shao, Qing; Pfaendtner, Jim; Jiang, Shaoyi

2013-06-20

Charged amino acids are the most common on surfaces of proteins and understanding the interactions between these charged amino acids, salt bridging, is crucial for understanding protein-protein interactions. Previous simulations have been limited to implicit solvent or fixed binding geometry due to the sampling required for converged free energies. Using well-tempered metadynamics, we have calculated salt bridge free energy surfaces in water and confirmed the results with NMR experiments. The simulations give binding free energies, quantitative ranking of salt bridging strength, and insights into the hydration of the salt bridges. The arginine-aspartate salt bridge was found to be the weakest and arginine-glutamate the strongest, showing that arginine can discriminate between aspartate and glutamate, whereas the salt bridges with lysine are indistinguishable in their free energy. The salt bridging hydration is found to be complementary to salt bridge orientation with arginine having specific orientations.

Capturing RNA Folding Free Energy with Coarse-Grained Molecular Dynamics Simulations

PubMed Central

Bell, David R.; Cheng, Sara Y.; Salazar, Heber; Ren, Pengyu

2017-01-01

We introduce a coarse-grained RNA model for molecular dynamics simulations, RACER (RnA CoarsE-gRained). RACER achieves accurate native structure prediction for a number of RNAs (average RMSD of 2.93 Å) and the sequence-specific variation of free energy is in excellent agreement with experimentally measured stabilities (R2 = 0.93). Using RACER, we identified hydrogen-bonding (or base pairing), base stacking, and electrostatic interactions as essential driving forces for RNA folding. Also, we found that separating pairing vs. stacking interactions allowed RACER to distinguish folded vs. unfolded states. In RACER, base pairing and stacking interactions each provide an approximate stability of 3–4 kcal/mol for an A-form helix. RACER was developed based on PDB structural statistics and experimental thermodynamic data. In contrast with previous work, RACER implements a novel effective vdW potential energy function, which led us to re-parameterize hydrogen bond and electrostatic potential energy functions. Further, RACER is validated and optimized using a simulated annealing protocol to generate potential energy vs. RMSD landscapes. Finally, RACER is tested using extensive equilibrium pulling simulations (0.86 ms total) on eleven RNA sequences (hairpins and duplexes). PMID:28393861

Simulation of Solar Energy Use in Livelihood of Buildings

NASA Astrophysics Data System (ADS)

Lvocich, I. Ya; Preobrazhenskiy, A. P.; Choporov, O. N.

2017-11-01

Solar energy can be considered as the most technological and economical type of renewable energy. The purpose of the paper is to increase the efficiency of solar energy utilization on the basis of the mathematical simulation of the solar collector. A mathematical model of the radiant heat transfer vacuum solar collector is clarified. The model was based on the process of radiative heat transfer between glass and copper walls with the defined blackness degrees. A mathematical model of the ether phase transition point is developed. The dependence of the reservoir walls temperature change on the ambient temperature over time is obtained. The results of the paper can be useful for the development of prospective sources using solar energy.

Molecular dynamics simulations studies and free energy analysis on inhibitors of MDM2-p53 interaction.

PubMed

Niu, Rui-Juan; Zheng, Qing-Chuan; Zhang, Ji-Long; Zhang, Hong-Xing

2013-11-01

The oncoprotein MDM2 (murine double minute 2) negatively regulates the activity and stability of tumor suppressor p53. Inactivation of the MDM2-p53 interaction by potent inhibitors offers new possibilities for anticancer therapy. Molecular dynamics (MD) simulations were performed on three inhibitors-MDM2 complexes to investigate the stability and structural transitions. Simulations show that the backbone of MDM2 maintains stable during the whole time. However, slightly structural changes of inhibitors and MDM2 are observed. Furthermore, the molecular mechanics generalized Born surface area (MM-GBSA) approach was introduced to analyze the interactions between inhibitors and MDM2. The results show that binding of inhibitor pDIQ to MDM2 is significantly stronger than that of pMI and pDI to MDM2. The side chains of residues have more contribution than backbone of residues in energy decomposition. The structure-affinity analyses show that L54, I61, M62, Y67, Q72, H73 and V93 produce important interaction energy with inhibitors. The residue W/Y22' is also very important to the interaction between the inhibitors and MDM2. The three-dimensional structures at different times indicate that the mobility of Y100 influences on the binding of inhibitors to MDM2, and its change has important role in conformations of inhibitors and MDM2. Copyright © 2013 Elsevier Inc. All rights reserved.

Alchemical free energy simulations for biological complexes: powerful but temperamental....

PubMed

Aleksandrov, Alexey; Thompson, Damien; Simonson, Thomas

2010-01-01

Free energy simulations compare multiple ligand:receptor complexes by "alchemically" transforming one into another, yielding binding free energy differences. Since their introduction in the 1980s, many technical and theoretical obstacles were surmounted, and the method ("MDFE," since molecular dynamics are often used) has matured into a powerful tool. We describe its current status, its effectiveness, and the challenges it faces. MDFE has provided chemical accuracy for many systems but remains expensive, with significant human overhead costs. The bottlenecks have shifted, partly due to increased computer power. To study diverse sets of ligands, force field availability and accuracy can be a major difficulty. Another difficulty is the frequent need to consider multiple states, related to sidechain protonation or buried waters, for example. Sophisticated, automated methods to sample these states are maturing, such as constant pH simulations. Meanwhile, combinations of MDFE and simpler approaches, like continuum dielectric models, can be very effective. As illustrations, we show how, with careful force field parameterization, MDFE accurately predicts binding specificities between complex tetracycline ligands and their targets. We describe substrate binding to the aspartyl-tRNA synthetase enzyme, where many distinct electrostatic states play a role, and a histidine and a Mg(2+) ion act as coupled switches that help enforce a strict preference for the aspartate substrate, relative to several analogs. Overall, MDFE has achieved a predictive status, where novel ligands can be studied and molecular recognition elucidated in depth. It should play an increasing role in the analysis of complex cellular processes and biomolecular engineering. 2009 John Wiley & Sons, Ltd.

Energy levels scheme simulation of divalent cobalt doped bismuth germanate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andreici, Emiliana-Laura, E-mail: andreicilaura@yahoo.com; Petkova, Petya; Avram, Nicolae M.

The aim of this paper is to simulate the energy levels scheme for Bismuth Germanate (BGO) doped with divalent cobalt, in order to give a reliable explanation for spectral experimental data. In the semiempirical crystal field theory we first modeled the Crystal Field Parameters (CFPs) of BGO:Cr{sup 2+} system, in the frame of Exchange Charge Model (ECM), with actually site symmetry of the impurity ions after doping. The values of CFPs depend on the geometry of doped host matrix and by parameter G of ECM. First, we optimized the geometry of undoped BGO host matrix and afterwards, that of dopedmore » BGO with divalent cobalt. The charges effect of ligands and covalence bonding between cobalt cations and oxygen anions, in the cluster approach, also were taken into account. With the obtained values of the CFPs we simulate the energy levels scheme of cobalt ions, by diagonalizing the matrix of the doped crystal Hamiltonian. Obviously, energy levels and estimated Racah parameters B and C were compared with the experimental spectroscopic data and discussed. Comparison of obtained results with experimental data shows quite satisfactory, which justify the model and simulation schemes used for the title system.« less

Simulation of Energy Savings in Automotive Coatings Processes

NASA Astrophysics Data System (ADS)

Gerini Romagnoli, Marco

Recently, the automakers have become more and more aware of the environmental and economic impact of their manufacturing processes. The paint shop is the largest energy user in a vehicle manufacturing plant, and one way to reduce costs and energy usage is the optimization of this area. This project aims at providing a tool to model and simulate a paint shop, in order to run and analyze some scenarios and case studies, helping to take strategic decisions. Analytical computations and real data were merged to build a tool that can be used by FCA for their Sterling Heights plant. Convection and conduction heat losses were modeled for the dip processes and the ovens. Thermal balances were used to compute the consumptions of booths, decks and ovens, while pump and fan energy consumptions were modeled for each sub-process. The user acts on a calendar, scheduling a year of production, and the model predicts the energy consumption of the paint shop. Five scenarios were run to test different conditions and the influence of scheduling on the energy consumption. Two different sets of production schedules have been evaluated, the first one fulfilling the production requirement in one shift of 10 hours, at high rate, the second one using two 7-hour-long shifts at medium production rate. It was found that the unit cost was minimized in the warmest months of spring and fall, and system shutdown was a crucial factor to reduce energy consumption. A fifth hypothetical scenario was run, with a 4 month continuous production and an 8 month total shutdown, which reduced the energy consumption to a half of the best realistic scenario. When the plant was run in a two-shifts configuration, the cost to coat a vehicle was found to be 29 with weekend shutdown, and 39 without. In the one-shift configuration, the cost was slightly higher, but the difference was less than 5%. While the fifth scenario showed a consistent reduction of the unit cost, inventory and logistic expenses deriving from the

Stochastic simulation and analysis of biomolecular reaction networks

PubMed Central

Frazier, John M; Chushak, Yaroslav; Foy, Brent

2009-01-01

Background In recent years, several stochastic simulation algorithms have been developed to generate Monte Carlo trajectories that describe the time evolution of the behavior of biomolecular reaction networks. However, the effects of various stochastic simulation and data analysis conditions on the observed dynamics of complex biomolecular reaction networks have not recieved much attention. In order to investigate these issues, we employed a a software package developed in out group, called Biomolecular Network Simulator (BNS), to simulate and analyze the behavior of such systems. The behavior of a hypothetical two gene in vitro transcription-translation reaction network is investigated using the Gillespie exact stochastic algorithm to illustrate some of the factors that influence the analysis and interpretation of these data. Results Specific issues affecting the analysis and interpretation of simulation data are investigated, including: (1) the effect of time interval on data presentation and time-weighted averaging of molecule numbers, (2) effect of time averaging interval on reaction rate analysis, (3) effect of number of simulations on precision of model predictions, and (4) implications of stochastic simulations on optimization procedures. Conclusion The two main factors affecting the analysis of stochastic simulations are: (1) the selection of time intervals to compute or average state variables and (2) the number of simulations generated to evaluate the system behavior. PMID:19534796

Comparison of Moist Static Energy and Budget between the GCM-Simulated Madden–Julian Oscillation and Observations over the Indian Ocean and Western Pacific

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Xiaoqing; Deng, Liping

The moist static energy (MSE) anomalies and MSE budget associated with the Madden–Julian oscillation (MJO) simulated in the Iowa State University General Circulation Model (ISUGCM) over the Indian and Pacific Oceans are compared with observations. Different phase relationships between MJO 850-hPa zonal wind, precipitation, and surface latent heat flux are simulated over the Indian Ocean and western Pacific, which are greatly influenced by the convection closure, trigger conditions, and convective momentum transport (CMT). The moist static energy builds up from the lower troposphere 15–20 days before the peak of MJO precipitation, and reaches the maximum in the middle troposphere (500–600more » hPa) near the peak of MJO precipitation. The gradual lower-tropospheric heating and moistening and the upward transport of moist static energy are important aspects of MJO events, which are documented in observational studies but poorly simulated in most GCMs. The trigger conditions for deep convection, obtained from the year-long cloud resolving model (CRM) simulations, contribute to the striking difference between ISUGCM simulations with the original and modified convection schemes and play the major role in the improved MJO simulation in ISUGCM. Additionally, the budget analysis with the ISUGCM simulations shows the increase in MJO MSE is in phase with the horizontal advection of MSE over the western Pacific, while out of phase with the horizontal advection of MSE over the Indian Ocean. However, the NCEP analysis shows that the tendency of MJO MSE is in phase with the horizontal advection of MSE over both oceans.« less

A strategy for analysis of (molecular) equilibrium simulations: Configuration space density estimation, clustering, and visualization

NASA Astrophysics Data System (ADS)

Hamprecht, Fred A.; Peter, Christine; Daura, Xavier; Thiel, Walter; van Gunsteren, Wilfred F.

2001-02-01

We propose an approach for summarizing the output of long simulations of complex systems, affording a rapid overview and interpretation. First, multidimensional scaling techniques are used in conjunction with dimension reduction methods to obtain a low-dimensional representation of the configuration space explored by the system. A nonparametric estimate of the density of states in this subspace is then obtained using kernel methods. The free energy surface is calculated from that density, and the configurations produced in the simulation are then clustered according to the topography of that surface, such that all configurations belonging to one local free energy minimum form one class. This topographical cluster analysis is performed using basin spanning trees which we introduce as subgraphs of Delaunay triangulations. Free energy surfaces obtained in dimensions lower than four can be visualized directly using iso-contours and -surfaces. Basin spanning trees also afford a glimpse of higher-dimensional topographies. The procedure is illustrated using molecular dynamics simulations on the reversible folding of peptide analoga. Finally, we emphasize the intimate relation of density estimation techniques to modern enhanced sampling algorithms.

Teaching a Model-based Climatology Using Energy Balance Simulation.

ERIC Educational Resources Information Center

Unwin, David

1981-01-01

After outlining the difficulties of teaching climatology within an undergraduate geography curriculum, the author describes and evaluates the use of a computer assisted simulation to model surface energy balance and the effects of land use changes on local climate. (AM)

Data and Tools | Energy Analysis | NREL

Science.gov Websites

and Tools Energy Analysis Data and Tools NREL develops energy analysis data and tools to assess collections. Data Products Technology and Performance Analysis Tools Energy Systems Analysis Tools Economic and Financial Analysis Tools

Simulated quantum computation of molecular energies.

PubMed

Aspuru-Guzik, Alán; Dutoi, Anthony D; Love, Peter J; Head-Gordon, Martin

2005-09-09

The calculation time for the energy of atoms and molecules scales exponentially with system size on a classical computer but polynomially using quantum algorithms. We demonstrate that such algorithms can be applied to problems of chemical interest using modest numbers of quantum bits. Calculations of the water and lithium hydride molecular ground-state energies have been carried out on a quantum computer simulator using a recursive phase-estimation algorithm. The recursive algorithm reduces the number of quantum bits required for the readout register from about 20 to 4. Mappings of the molecular wave function to the quantum bits are described. An adiabatic method for the preparation of a good approximate ground-state wave function is described and demonstrated for a stretched hydrogen molecule. The number of quantum bits required scales linearly with the number of basis functions, and the number of gates required grows polynomially with the number of quantum bits.

Large-scale energy budget of impulsive magnetic reconnection: Theory and simulation.

PubMed

Kiehas, S A; Volkonskaya, N N; Semenov, V S; Erkaev, N V; Kubyshkin, I V; Zaitsev, I V

2017-03-01

We evaluate the large-scale energy budget of magnetic reconnection utilizing an analytical time-dependent impulsive reconnection model and a numerical 2-D MHD simulation. With the generalization to compressible plasma, we can investigate changes in the thermal, kinetic, and magnetic energies. We study these changes in three different regions: (a) the region defined by the outflowing plasma (outflow region, OR), (b) the region of compressed magnetic fields above/below the OR (traveling compression region, TCR), and (c) the region trailing the OR and TCR (wake). For incompressible plasma, we find that the decrease inside the OR is compensated by the increase in kinetic energy. However, for the general compressible case, the decrease in magnetic energy inside the OR is not sufficient to explain the increase in thermal and kinetic energy. Hence, energy from other regions needs to be considered. We find that the decrease in thermal and magnetic energy in the wake, together with the decrease in magnetic energy inside the OR, is sufficient to feed the increase in kinetic and thermal energies in the OR and the increase in magnetic and thermal energies inside the TCR. That way, the energy budget is balanced, but consequently, not all magnetic energy is converted into kinetic and thermal energies of the OR. Instead, a certain fraction gets transfered into the TCR. As an upper limit of the efficiency of reconnection (magnetic energy → kinetic energy) we find η eff =1/2. A numerical simulation is used to include a finite thickness of the current sheet, which shows the importance of the pressure gradient inside the OR for the conversion of kinetic energy into thermal energy.

Statistical Energy Analysis (SEA) and Energy Finite Element Analysis (EFEA) Predictions for a Floor-Equipped Composite Cylinder

NASA Technical Reports Server (NTRS)

Grosveld, Ferdinand W.; Schiller, Noah H.; Cabell, Randolph H.

2011-01-01

Comet Enflow is a commercially available, high frequency vibroacoustic analysis software founded on Energy Finite Element Analysis (EFEA) and Energy Boundary Element Analysis (EBEA). Energy Finite Element Analysis (EFEA) was validated on a floor-equipped composite cylinder by comparing EFEA vibroacoustic response predictions with Statistical Energy Analysis (SEA) and experimental results. Statistical Energy Analysis (SEA) predictions were made using the commercial software program VA One 2009 from ESI Group. The frequency region of interest for this study covers the one-third octave bands with center frequencies from 100 Hz to 4000 Hz.

Improving Energy Efficiency for the Vehicle Assembly Industry: A Discrete Event Simulation Approach

NASA Astrophysics Data System (ADS)

Oumer, Abduaziz; Mekbib Atnaw, Samson; Kie Cheng, Jack; Singh, Lakveer

2016-11-01

This paper presented a Discrete Event Simulation (DES) model for investigating and improving energy efficiency in vehicle assembly line. The car manufacturing industry is one of the highest energy consuming industries. Using Rockwell Arena DES package; a detailed model was constructed for an actual vehicle assembly plant. The sources of energy considered in this research are electricity and fuel; which are the two main types of energy sources used in a typical vehicle assembly plant. The model depicts the performance measurement for process- specific energy measures of painting, welding, and assembling processes. Sound energy efficiency model within this industry has two-fold advantage: reducing CO2 emission and cost reduction associated with fuel and electricity consumption. The paper starts with an overview of challenges in energy consumption within the facilities of automotive assembly line and highlights the parameters for energy efficiency. The results of the simulation model indicated improvements for energy saving objectives and reduced costs.

Energy loss analysis of an integrated space power distribution system

NASA Technical Reports Server (NTRS)

Kankam, M. D.; Ribeiro, P. F.

1992-01-01

The results of studies related to conceptual topologies of an integrated utility-like space power system are described. The system topologies are comparatively analyzed by considering their transmission energy losses as functions of mainly distribution voltage level and load composition. The analysis is expedited by use of a Distribution System Analysis and Simulation (DSAS) software. This recently developed computer program by the Electric Power Research Institute (EPRI) uses improved load models to solve the power flow within the system. However, present shortcomings of the software with regard to space applications, and incompletely defined characteristics of a space power system make the results applicable to only the fundamental trends of energy losses of the topologies studied. Accountability, such as included, for the effects of the various parameters on the system performance can constitute part of a planning tool for a space power distribution system.

IFC BIM-Based Methodology for Semi-Automated Building Energy Performance Simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bazjanac, Vladimir

2008-07-01

Building energy performance (BEP) simulation is still rarely used in building design, commissioning and operations. The process is too costly and too labor intensive, and it takes too long to deliver results. Its quantitative results are not reproducible due to arbitrary decisions and assumptions made in simulation model definition, and can be trusted only under special circumstances. A methodology to semi-automate BEP simulation preparation and execution makes this process much more effective. It incorporates principles of information science and aims to eliminate inappropriate human intervention that results in subjective and arbitrary decisions. This is achieved by automating every part ofmore » the BEP modeling and simulation process that can be automated, by relying on data from original sources, and by making any necessary data transformation rule-based and automated. This paper describes the new methodology and its relationship to IFC-based BIM and software interoperability. It identifies five steps that are critical to its implementation, and shows what part of the methodology can be applied today. The paper concludes with a discussion of application to simulation with EnergyPlus, and describes data transformation rules embedded in the new Geometry Simplification Tool (GST).« less

Correcting for the free energy costs of bond or angle constraints in molecular dynamics simulations

PubMed Central

König, Gerhard; Brooks, Bernard R.

2014-01-01

Background Free energy simulations are an important tool in the arsenal of computational biophysics, allowing the calculation of thermodynamic properties of binding or enzymatic reactions. This paper introduces methods to increase the accuracy and precision of free energy calculations by calculating the free energy costs of constraints during post-processing. The primary purpose of employing constraints for these free energy methods is to increase the phase space overlap between ensembles, which is required for accuracy and convergence. Methods The free energy costs of applying or removing constraints are calculated as additional explicit steps in the free energy cycle. The new techniques focus on hard degrees of freedom and use both gradients and Hessian estimation. Enthalpy, vibrational entropy, and Jacobian free energy terms are considered. Results We demonstrate the utility of this method with simple classical systems involving harmonic and anharmonic oscillators, four-atomic benchmark systems, an alchemical mutation of ethane to methanol, and free energy simulations between alanine and serine. The errors for the analytical test cases are all below 0.0007 kcal/mol, and the accuracy of the free energy results of ethane to methanol is improved from 0.15 to 0.04 kcal/mol. For the alanine to serine case, the phase space overlaps of the unconstrained simulations range between 0.15 and 0.9%. The introduction of constraints increases the overlap up to 2.05%. On average, the overlap increases by 94% relative to the unconstrained value and precision is doubled. Conclusions The approach reduces errors arising from constraints by about an order of magnitude. Free energy simulations benefit from the use of constraints through enhanced convergence and higher precision. General Significance The primary utility of this approach is to calculate free energies for systems with disparate energy surfaces and bonded terms, especially in multi-scale molecular mechanics

Free energy simulations with the AMOEBA polarizable force field and metadynamics on GPU platform.

PubMed

Peng, Xiangda; Zhang, Yuebin; Chu, Huiying; Li, Guohui

2016-03-05

The free energy calculation library PLUMED has been incorporated into the OpenMM simulation toolkit, with the purpose to perform enhanced sampling MD simulations using the AMOEBA polarizable force field on GPU platform. Two examples, (I) the free energy profile of water pair separation (II) alanine dipeptide dihedral angle free energy surface in explicit solvent, are provided here to demonstrate the accuracy and efficiency of our implementation. The converged free energy profiles could be obtained within an affordable MD simulation time when the AMOEBA polarizable force field is employed. Moreover, the free energy surfaces estimated using the AMOEBA polarizable force field are in agreement with those calculated from experimental data and ab initio methods. Hence, the implementation in this work is reliable and would be utilized to study more complicated biological phenomena in both an accurate and efficient way. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

HVAC modifications and computerized energy analysis for the Operations Support Building at the Mars Deep Space Station at Goldstone

NASA Technical Reports Server (NTRS)

Halperin, A.; Stelzmuller, P.

1986-01-01

The key heating, ventilation, and air-conditioning (HVAC) modifications implemented at the Mars Deep Space Station's Operation Support Building at Jet Propulsion Laboratories (JPL) in order to reduce energy consumption and decrease operating costs are described. An energy analysis comparison between the computer simulated model for the building and the actual meter data was presented. The measurement performance data showed that the cumulative energy savings was about 21% for the period 1979 to 1981. The deviation from simulated data to measurement performance data was only about 3%.

A simulation model for wind energy storage systems. Volume 2: Operation manual

NASA Technical Reports Server (NTRS)

Warren, A. W.; Edsinger, R. W.; Burroughs, J. D.

1977-01-01

A comprehensive computer program (SIMWEST) developed for the modeling of wind energy/storage systems utilizing any combination of five types of storage (pumped hydro, battery, thermal, flywheel, and pneumatic) is described. Features of the program include: a precompiler which generates computer models (in FORTRAN) of complex wind source/storage/application systems, from user specifications using the respective library components; a program which provides the techno-economic system analysis with the respective I/O the integration of system dynamics, and the iteration for conveyance of variables; and capability to evaluate economic feasibility as well as general performance of wind energy systems. The SIMWEST operation manual is presented and the usage of the SIMWEST program and the design of the library components are described. A number of example simulations intended to familiarize the user with the program's operation is given along with a listing of each SIMWEST library subroutine.

Simulation of the outdoor energy efficiency of an autonomous solar kit based on meteorological data for a site in Central Europa

NASA Astrophysics Data System (ADS)

Bouzaki, Mohammed Moustafa; Chadel, Meriem; Benyoucef, Boumediene; Petit, Pierre; Aillerie, Michel

2016-07-01

This contribution analyzes the energy provided by a solar kit dedicated to autonomous usage and installed in Central Europa (Longitude 6.10°; Latitude 49.21° and Altitude 160 m) by using the simulation software PVSYST. We focused the analysis on the effect of temperature and solar irradiation on the I-V characteristic of a commercial PV panel. We also consider in this study the influence of charging and discharging the battery on the generator efficiency. Meteorological data are integrated into the simulation software. As expected, the solar kit provides an energy varying all along the year with a minimum in December. In the proposed approach, we consider this minimum as the lowest acceptable energy level to satisfy the use. Thus for the other months, a lost in the available renewable energy exists if no storage system is associated.

Integrating software architectures for distributed simulations and simulation analysis communities.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldsby, Michael E.; Fellig, Daniel; Linebarger, John Michael

2005-10-01

The one-year Software Architecture LDRD (No.79819) was a cross-site effort between Sandia California and Sandia New Mexico. The purpose of this research was to further develop and demonstrate integrating software architecture frameworks for distributed simulation and distributed collaboration in the homeland security domain. The integrated frameworks were initially developed through the Weapons of Mass Destruction Decision Analysis Center (WMD-DAC), sited at SNL/CA, and the National Infrastructure Simulation & Analysis Center (NISAC), sited at SNL/NM. The primary deliverable was a demonstration of both a federation of distributed simulations and a federation of distributed collaborative simulation analysis communities in the context ofmore » the same integrated scenario, which was the release of smallpox in San Diego, California. To our knowledge this was the first time such a combination of federations under a single scenario has ever been demonstrated. A secondary deliverable was the creation of the standalone GroupMeld{trademark} collaboration client, which uses the GroupMeld{trademark} synchronous collaboration framework. In addition, a small pilot experiment that used both integrating frameworks allowed a greater range of crisis management options to be performed and evaluated than would have been possible without the use of the frameworks.« less

Water Quality Analysis Simulation

EPA Pesticide Factsheets

The Water Quality analysis simulation Program, an enhancement of the original WASP. This model helps users interpret and predict water quality responses to natural phenomena and man-made pollution for variious pollution management decisions.

The Chemistry of Shocked High-energy Materials: Connecting Atomistic Simulations to Experiments

NASA Astrophysics Data System (ADS)

Islam, Md Mahbubul; Strachan, Alejandro

2017-06-01

A comprehensive atomistic-level understanding of the physics and chemistry of shocked high energy (HE) materials is crucial for designing safe and efficient explosives. Advances in the ultrafast spectroscopy and laser shocks enabled the study of shock-induced chemistry at extreme conditions occurring at picosecond timescales. Despite this progress experiments are not without limitations and do not enable a direct characterization of chemical reactions. At the same time, large-scale reactive molecular dynamics (MD) simulations are capable of providing description of the shocked-induced chemistry but the uncertainties resulting from the use of approximate descriptions of atomistic interactions remain poorly quantified. We use ReaxFF MD simulations to investigate the shock and temperature induced chemical decomposition mechanisms of polyvinyl nitrate, RDX, and nitromethane. The effect of various shock pressures on reaction initiation mechanisms is investigated for all three materials. We performed spectral analysis from atomistic velocities at different shock pressures to enable direct comparison with experiments. The simulations predict volume-increasing reactions at the shock-to-detonation transitions and the shock vs. particle velocity data are in good agreement with available experimental data. The ReaxFF MD simulations validated against experiments enabled prediction of reaction kinetics of shocked materials, and interpretation of experimental spectroscopy data via assignment of the spectral peaks to dictate various reaction pathways at extreme conditions.

The Importance of Simulation Workflow and Data Management in the Accelerated Climate Modeling for Energy Project

NASA Astrophysics Data System (ADS)

Bader, D. C.

2015-12-01

The Accelerated Climate Modeling for Energy (ACME) Project is concluding its first year. Supported by the Office of Science in the U.S. Department of Energy (DOE), its vision is to be "an ongoing, state-of-the-science Earth system modeling, modeling simulation and prediction project that optimizes the use of DOE laboratory resources to meet the science needs of the nation and the mission needs of DOE." Included in the "laboratory resources," is a large investment in computational, network and information technologies that will be utilized to both build better and more accurate climate models and broadly disseminate the data they generate. Current model diagnostic analysis and data dissemination technologies will not scale to the size of the simulations and the complexity of the models envisioned by ACME and other top tier international modeling centers. In this talk, the ACME Workflow component plans to meet these future needs will be described and early implementation examples will be highlighted.

Improved Reweighting of Accelerated Molecular Dynamics Simulations for Free Energy Calculation.

PubMed

Miao, Yinglong; Sinko, William; Pierce, Levi; Bucher, Denis; Walker, Ross C; McCammon, J Andrew

2014-07-08

Accelerated molecular dynamics (aMD) simulations greatly improve the efficiency of conventional molecular dynamics (cMD) for sampling biomolecular conformations, but they require proper reweighting for free energy calculation. In this work, we systematically compare the accuracy of different reweighting algorithms including the exponential average, Maclaurin series, and cumulant expansion on three model systems: alanine dipeptide, chignolin, and Trp-cage. Exponential average reweighting can recover the original free energy profiles easily only when the distribution of the boost potential is narrow (e.g., the range ≤20 k B T) as found in dihedral-boost aMD simulation of alanine dipeptide. In dual-boost aMD simulations of the studied systems, exponential average generally leads to high energetic fluctuations, largely due to the fact that the Boltzmann reweighting factors are dominated by a very few high boost potential frames. In comparison, reweighting based on Maclaurin series expansion (equivalent to cumulant expansion on the first order) greatly suppresses the energetic noise but often gives incorrect energy minimum positions and significant errors at the energy barriers (∼2-3 k B T). Finally, reweighting using cumulant expansion to the second order is able to recover the most accurate free energy profiles within statistical errors of ∼ k B T, particularly when the distribution of the boost potential exhibits low anharmonicity (i.e., near-Gaussian distribution), and should be of wide applicability. A toolkit of Python scripts for aMD reweighting "PyReweighting" is distributed free of charge at http://mccammon.ucsd.edu/computing/amdReweighting/.

Improved Reweighting of Accelerated Molecular Dynamics Simulations for Free Energy Calculation

PubMed Central

2015-01-01

Accelerated molecular dynamics (aMD) simulations greatly improve the efficiency of conventional molecular dynamics (cMD) for sampling biomolecular conformations, but they require proper reweighting for free energy calculation. In this work, we systematically compare the accuracy of different reweighting algorithms including the exponential average, Maclaurin series, and cumulant expansion on three model systems: alanine dipeptide, chignolin, and Trp-cage. Exponential average reweighting can recover the original free energy profiles easily only when the distribution of the boost potential is narrow (e.g., the range ≤20kBT) as found in dihedral-boost aMD simulation of alanine dipeptide. In dual-boost aMD simulations of the studied systems, exponential average generally leads to high energetic fluctuations, largely due to the fact that the Boltzmann reweighting factors are dominated by a very few high boost potential frames. In comparison, reweighting based on Maclaurin series expansion (equivalent to cumulant expansion on the first order) greatly suppresses the energetic noise but often gives incorrect energy minimum positions and significant errors at the energy barriers (∼2–3kBT). Finally, reweighting using cumulant expansion to the second order is able to recover the most accurate free energy profiles within statistical errors of ∼kBT, particularly when the distribution of the boost potential exhibits low anharmonicity (i.e., near-Gaussian distribution), and should be of wide applicability. A toolkit of Python scripts for aMD reweighting “PyReweighting” is distributed free of charge at http://mccammon.ucsd.edu/computing/amdReweighting/. PMID:25061441

Cost Benefit and Alternatives Analysis of Distribution Systems with Energy Storage Systems: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harris, Tom; Nagarajan, Adarsh; Baggu, Murali

This paper explores monetized and non-monetized benefits from storage interconnected to distribution system through use cases illustrating potential applications for energy storage in California's electric utility system. This work supports SDG&E in its efforts to quantify, summarize, and compare the cost and benefit streams related to implementation and operation of energy storage on its distribution feeders. This effort develops the cost benefit and alternatives analysis platform, integrated with QSTS feeder simulation capability, and analyzed use cases to explore the cost-benefit of implementation and operation of energy storage for feeder support and market participation.

Effects of a Caffeine-Containing Energy Drink on Simulated Soccer Performance

PubMed Central

Del Coso, Juan; Muñoz-Fernández, Víctor E.; Muñoz, Gloria; Fernández-Elías, Valentín E.; Ortega, Juan F.; Hamouti, Nassim; Barbero, José C.; Muñoz-Guerra, Jesús

2012-01-01

Background To investigate the effects of a caffeine-containing energy drink on soccer performance during a simulated game. A second purpose was to assess the post-exercise urine caffeine concentration derived from the energy drink intake. Methodology/Principal Findings Nineteen semiprofessional soccer players ingested 630±52 mL of a commercially available energy drink (sugar-free Red Bull®) to provide 3 mg of caffeine per kg of body mass, or a decaffeinated control drink (0 mg/kg). After sixty minutes they performed a 15-s maximal jump test, a repeated sprint test (7×30 m; 30 s of active recovery) and played a simulated soccer game. Individual running distance and speed during the game were measured using global positioning satellite (GPS) devices. In comparison to the control drink, the ingestion of the energy drink increased mean jump height in the jump test (34.7±4.7 v 35.8±5.5 cm; P<0.05), mean running speed during the sprint test (25.6±2.1 v 26.3±1.8 km · h−1; P<0.05) and total distance covered at a speed higher than 13 km · h−1 during the game (1205±289 v 1436±326 m; P<0.05). In addition, the energy drink increased the number of sprints during the whole game (30±10 v 24±8; P<0.05). Post-exercise urine caffeine concentration was higher after the energy drink than after the control drink (4.1±1.0 v 0.1±0.1 µg · mL−1; P<0.05). Conclusions/significance A caffeine-containing energy drink in a dose equivalent to 3 mg/kg increased the ability to repeatedly sprint and the distance covered at high intensity during a simulated soccer game. In addition, the caffeinated energy drink increased jump height which may represent a meaningful improvement for headers or when players are competing for a ball. PMID:22348079

Effects of a caffeine-containing energy drink on simulated soccer performance.

PubMed

Del Coso, Juan; Muñoz-Fernández, Víctor E; Muñoz, Gloria; Fernández-Elías, Valentín E; Ortega, Juan F; Hamouti, Nassim; Barbero, José C; Muñoz-Guerra, Jesús

2012-01-01

To investigate the effects of a caffeine-containing energy drink on soccer performance during a simulated game. A second purpose was to assess the post-exercise urine caffeine concentration derived from the energy drink intake. Nineteen semiprofessional soccer players ingested 630 ± 52 mL of a commercially available energy drink (sugar-free Red Bull®) to provide 3 mg of caffeine per kg of body mass, or a decaffeinated control drink (0 mg/kg). After sixty minutes they performed a 15-s maximal jump test, a repeated sprint test (7 × 30 m; 30 s of active recovery) and played a simulated soccer game. Individual running distance and speed during the game were measured using global positioning satellite (GPS) devices. In comparison to the control drink, the ingestion of the energy drink increased mean jump height in the jump test (34.7 ± 4.7 v 35.8 ± 5.5 cm; P<0.05), mean running speed during the sprint test (25.6 ± 2.1 v 26.3 ± 1.8 km · h(-1); P<0.05) and total distance covered at a speed higher than 13 km · h(-1) during the game (1205 ± 289 v 1436 ± 326 m; P<0.05). In addition, the energy drink increased the number of sprints during the whole game (30 ± 10 v 24 ± 8; P<0.05). Post-exercise urine caffeine concentration was higher after the energy drink than after the control drink (4.1 ± 1.0 v 0.1 ± 0.1 µg · mL(-1); P<0.05). A caffeine-containing energy drink in a dose equivalent to 3 mg/kg increased the ability to repeatedly sprint and the distance covered at high intensity during a simulated soccer game. In addition, the caffeinated energy drink increased jump height which may represent a meaningful improvement for headers or when players are competing for a ball.

Analysis of energy recovery potential using innovative technologies of waste gasification.

PubMed

Lombardi, Lidia; Carnevale, Ennio; Corti, Andrea

2012-04-01

In this paper, two alternative thermo-chemical processes for waste treatment were analysed: high temperature gasification and gasification associated to plasma process. The two processes were analysed from the thermodynamic point of view, trying to reconstruct two simplified models, using appropriate simulation tools and some support data from existing/planned plants, able to predict the energy recovery performances by process application. In order to carry out a comparative analysis, the same waste stream input was considered as input to the two models and the generated results were compared. The performances were compared with those that can be obtained from conventional combustion with energy recovery process by means of steam turbine cycle. Results are reported in terms of energy recovery performance indicators as overall energy efficiency, specific energy production per unit of mass of entering waste, primary energy source savings, specific carbon dioxide production. Copyright © 2011 Elsevier Ltd. All rights reserved.

Overcoming free energy barriers using unconstrained molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Hénin, Jérôme; Chipot, Christophe

2004-08-01

Association of unconstrained molecular dynamics (MD) and the formalisms of thermodynamic integration and average force [Darve and Pohorille, J. Chem. Phys. 115, 9169 (2001)] have been employed to determine potentials of mean force. When implemented in a general MD code, the additional computational effort, compared to other standard, unconstrained simulations, is marginal. The force acting along a chosen reaction coordinate ξ is estimated from the individual forces exerted on the chemical system and accumulated as the simulation progresses. The estimated free energy derivative computed for small intervals of ξ is canceled by an adaptive bias to overcome the barriers of the free energy landscape. Evolution of the system along the reaction coordinate is, thus, limited by its sole self-diffusion properties. The illustrative examples of the reversible unfolding of deca-L-alanine, the association of acetate and guanidinium ions in water, the dimerization of methane in water, and its transfer across the water liquid-vapor interface are examined to probe the efficiency of the method.

Simulation of the Atmospheric Boundary Layer for Wind Energy Applications

NASA Astrophysics Data System (ADS)

Marjanovic, Nikola

Energy production from wind is an increasingly important component of overall global power generation, and will likely continue to gain an even greater share of electricity production as world governments attempt to mitigate climate change and wind energy production costs decrease. Wind energy generation depends on wind speed, which is greatly influenced by local and synoptic environmental forcings. Synoptic forcing, such as a cold frontal passage, exists on a large spatial scale while local forcing manifests itself on a much smaller scale and could result from topographic effects or land-surface heat fluxes. Synoptic forcing, if strong enough, may suppress the effects of generally weaker local forcing. At the even smaller scale of a wind farm, upstream turbines generate wakes that decrease the wind speed and increase the atmospheric turbulence at the downwind turbines, thereby reducing power production and increasing fatigue loading that may damage turbine components, respectively. Simulation of atmospheric processes that span a considerable range of spatial and temporal scales is essential to improve wind energy forecasting, wind turbine siting, turbine maintenance scheduling, and wind turbine design. Mesoscale atmospheric models predict atmospheric conditions using observed data, for a wide range of meteorological applications across scales from thousands of kilometers to hundreds of meters. Mesoscale models include parameterizations for the major atmospheric physical processes that modulate wind speed and turbulence dynamics, such as cloud evolution and surface-atmosphere interactions. The Weather Research and Forecasting (WRF) model is used in this dissertation to investigate the effects of model parameters on wind energy forecasting. WRF is used for case study simulations at two West Coast North American wind farms, one with simple and one with complex terrain, during both synoptically and locally-driven weather events. The model's performance with different

Design and Analysis of Solar Smartflower Simulation by Solidwork Program

NASA Astrophysics Data System (ADS)

Mulyana, Tatang; Sebayang, Darwin; Fajrina, Fildzah; Raihan; Faizal, M.

2018-03-01

The potential of solar energy that is so large in Indonesia can be a driving force for the use of renewable energy as a solution for energy needs. Government with the community can utilize and optimize this technology to increase the electrification ratio up to 100% in all corners of Indonesia. Because of its modular and practical nature, making this technology easy to apply. One of the latest imported products that have started to be offered and sold in Indonesia but not yet widely used for solar power generation is the kind of smartflower. Before using the product, it is of course very important and immediately to undertake an in-depth study of the utilization, use, maintenance, repair, component supply and fabrication. The best way to know the above is through a review of the design and simulation. To meet this need, this paper presents a solar-smartflower design and then simulated using the facilities available in the solidwork program. Solid simulation express is a tool that serves to create power simulation of a design part modelling. With the simulation is very helpful at all to reduce errors in making design. Accurate or not a design created is also influenced by several other factors such as material objects, the silent part of the part, and the load given. The simulation is static simulation and body battery drop test, and based on the results of this simulation is known that the design results have been very satisfactory.

Parameter studies on the energy balance closure problem using large-eddy simulation

NASA Astrophysics Data System (ADS)

De Roo, Frederik; Banerjee, Tirtha; Mauder, Matthias

2017-04-01

The imbalance of the surface energy budget in eddy-covariance measurements is still a pending problem. A possible cause is the presence of land surface heterogeneity. Heterogeneities of the boundary layer scale or larger are most effective in influencing the boundary layer turbulence, and large-eddy simulations have shown that secondary circulations within the boundary layer can affect the surface energy budget. However, the precise influence of the surface characteristics on the energy imbalance and its partitioning is still unknown. To investigate the influence of surface variables on all the components of the flux budget under convective conditions, we set up a systematic parameter study by means of large-eddy simulation. For the study we use a virtual control volume approach, and we focus on idealized heterogeneity by considering spatially variable surface fluxes. The surface fluxes vary locally in intensity and these patches have different length scales. The main focus lies on heterogeneities of length scales of the kilometer scale and one decade smaller. For each simulation, virtual measurement towers are positioned at functionally different positions. We discriminate between the locally homogeneous towers, located within land use patches, with respect to the more heterogeneous towers, and find, among others, that the flux-divergence and the advection are strongly linearly related within each class. Furthermore, we seek correlators for the energy balance ratio and the energy residual in the simulations. Besides the expected correlation with measurable atmospheric quantities such as the friction velocity, boundary-layer depth and temperature and moisture gradients, we have also found an unexpected correlation with the temperature difference between sonic temperature and surface temperature. In additional simulations with a large number of virtual towers, we investigate higher order correlations, which can be linked to secondary circulations. In a companion

Correcting for the free energy costs of bond or angle constraints in molecular dynamics simulations.

PubMed

König, Gerhard; Brooks, Bernard R

2015-05-01

Free energy simulations are an important tool in the arsenal of computational biophysics, allowing the calculation of thermodynamic properties of binding or enzymatic reactions. This paper introduces methods to increase the accuracy and precision of free energy calculations by calculating the free energy costs of constraints during post-processing. The primary purpose of employing constraints for these free energy methods is to increase the phase space overlap between ensembles, which is required for accuracy and convergence. The free energy costs of applying or removing constraints are calculated as additional explicit steps in the free energy cycle. The new techniques focus on hard degrees of freedom and use both gradients and Hessian estimation. Enthalpy, vibrational entropy, and Jacobian free energy terms are considered. We demonstrate the utility of this method with simple classical systems involving harmonic and anharmonic oscillators, four-atomic benchmark systems, an alchemical mutation of ethane to methanol, and free energy simulations between alanine and serine. The errors for the analytical test cases are all below 0.0007kcal/mol, and the accuracy of the free energy results of ethane to methanol is improved from 0.15 to 0.04kcal/mol. For the alanine to serine case, the phase space overlaps of the unconstrained simulations range between 0.15 and 0.9%. The introduction of constraints increases the overlap up to 2.05%. On average, the overlap increases by 94% relative to the unconstrained value and precision is doubled. The approach reduces errors arising from constraints by about an order of magnitude. Free energy simulations benefit from the use of constraints through enhanced convergence and higher precision. The primary utility of this approach is to calculate free energies for systems with disparate energy surfaces and bonded terms, especially in multi-scale molecular mechanics/quantum mechanics simulations. This article is part of a Special Issue

Modeling and simulation research on electromagnetic and energy-recycled damper based on Adams

NASA Astrophysics Data System (ADS)

Zhou, C. F.; Zhang, K.; Zhang, Pengfei

2018-05-01

In order to study the voltage and power output characteristics of the electromagnetic and energy-recycled damper which consists of gear, rack and generator, the Adams model of this damper and the Simulink model of generator are established, and the co-simulation is accomplished with these two models. The output indexes such as the gear speed and power of generator are obtained by the simulation, and the simulation results demonstrate that the voltage peak of the damper is 25 V; the maximum output power of the damper is 8 W. The above research provides a basis for the prototype development of electromagnetic and energy-recycled damper with gear and rack.

Determination of Membrane-Insertion Free Energies by Molecular Dynamics Simulations

PubMed Central

Gumbart, James; Roux, Benoît

2012-01-01

The accurate prediction of membrane-insertion probability for arbitrary protein sequences is a critical challenge to identifying membrane proteins and determining their folded structures. Although algorithms based on sequence statistics have had moderate success, a complete understanding of the energetic factors that drive the insertion of membrane proteins is essential to thoroughly meeting this challenge. In the last few years, numerous attempts to define a free-energy scale for amino-acid insertion have been made, yet disagreement between most experimental and theoretical scales persists. However, for a recently resolved water-to-bilayer scale, it is found that molecular dynamics simulations that carefully mimic the conditions of the experiment can reproduce experimental free energies, even when using the same force field as previous computational studies that were cited as evidence of this disagreement. Therefore, it is suggested that experimental and simulation-based scales can both be accurate and that discrepancies stem from disparities in the microscopic processes being considered rather than methodological errors. Furthermore, these disparities make the development of a single universally applicable membrane-insertion free energy scale difficult. PMID:22385850

Variations in laser energy outputs over a series of simulated treatments.

PubMed

Lister, T S; Brewin, M P

2014-10-01

Test patches are routinely employed to determine the likely efficacy and the risk of adverse effects from cutaneous laser treatments. However, the degree to which these represent a full treatment has not been investigated in detail. This study aimed to determine the variability in pulse-to-pulse output energy from a representative selection of cutaneous laser systems in order to assess the value of laser test patches. The output energies of each pulse from seven cutaneous laser systems were measured using a pyroelectric measurement head over a 2-h period, employing a regime of 10-min simulated treatments followed by a 5-min rest period (between patients). Each laser system appeared to demonstrate a different pattern of variation in output energy per pulse over the period measured. The output energies from a range of cutaneous laser systems have been shown to vary considerably between a representative test patch and a full treatment, and over the course of an entire simulated clinic list. © 2014 British Association of Dermatologists.

US Clean Energy Sector and the Opportunity for Modeling and Simulation

NASA Technical Reports Server (NTRS)

Inge, Carole Cameron

2011-01-01

The following paper sets forth the current understanding of the US clean energy demand and opportunity. As clean energy systems come online and technology is developed, modeling and simulation of these complex energy programs provides an untapped business opportunity. The US Department of Defense provides a great venue for developing new technology in the energy sector because it is demanding lower fuel costs, more energy efficiencies in its buildings and bases, and overall improvements in its carbon footprint. These issues coupled with the security issues faced by foreign dependence on oil will soon bring more clean energy innovations to the forefront (lighter batteries for soldiers, alternative fuel for jets, energy storage systems for ships, etc).

Energy expenditure during competitive Latin American dancing simulation.

PubMed

Massidda, Myosotis; Cugusi, Lucia; Ibba, Maurizio; Tradori, Iosto; Calò, Carla Maria

2011-12-01

The aims of this study were to estimate the energy expenditure (EE) and the intensity of physical activity (PA) during a competitive simulation of Latin American dancing and to evaluate the differences in PA and EE values between the sexes, between different dance types, and between the various phases of the competition. Ten Italian dancers (five couples, 5 males and 5 females) competing in Latin American dancing at the international level were examined in this study. The EE (kcal) was measured during the semifinal and final phases of the competition using the SenseWear Pro Armband (SWA). Paired-sample t-tests were used to determine differences in the metabolic equivalent (MET) and EE values between the semifinal and final phases and between each dance. One-way analysis of variance was used to analyze the differences in the MET and EE values between the sexes. The intensity of PA during the dance sequence ranged from moderate (3 to 6 METs) to vigorous (6 to 9 METs). The male dancers had higher EE values than the female dancers during all phases of the simulation. Similar MET values were observed in both sexes. The PA intensity during the finals phase was vigorous for 56% of the time of dance. Of all the dance styles, the rumba had the lowest MET and EE values. Our results demonstrate that competitive Latin American dancing is a heavy exercise and suggest that monitoring variables during normal training can improve training protocols and the dancers' fitness levels.

Levelized Cost of Energy Calculator | Energy Analysis | NREL

Science.gov Websites

Levelized Cost of Energy Calculator Levelized Cost of Energy Calculator Transparent Cost Database Button The levelized cost of energy (LCOE) calculator provides a simple calculator for both utility-scale need to be included for a thorough analysis. To estimate simple cost of energy, use the slider controls

Predicting the Macroscopic Fracture Energy of Epoxy Resins from Atomistic Molecular Simulations

DOE PAGES

Meng, Zhaoxu; Bessa, Miguel A.; Xia, Wenjie; ...

2016-12-06

Predicting the macroscopic fracture energy of highly crosslinked glassy polymers from atomistic simulations is challenging due to the size of the process zone being large in these systems. Here, we present a scale-bridging approach that links atomistic molecular dynamics simulations to macroscopic fracture properties on the basis of a continuum fracture mechanics model for two different epoxy materials. Our approach reveals that the fracture energy of epoxy resins strongly depends on the functionality of epoxy resin and the component ratio between the curing agent (amine) and epoxide. The most intriguing part of our study is that we demonstrate that themore » fracture energy exhibits a maximum value within the range of conversion degrees considered (from 65% to 95%), which can be attributed to the combined effects of structural rigidity and post-yield deformability. Our study provides physical insight into the molecular mechanisms that govern the fracture characteristics of epoxy resins and demonstrates the success of utilizing atomistic molecular simulations towards predicting macroscopic material properties.« less

Predicting the Macroscopic Fracture Energy of Epoxy Resins from Atomistic Molecular Simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, Zhaoxu; Bessa, Miguel A.; Xia, Wenjie

Predicting the macroscopic fracture energy of highly crosslinked glassy polymers from atomistic simulations is challenging due to the size of the process zone being large in these systems. Here, we present a scale-bridging approach that links atomistic molecular dynamics simulations to macroscopic fracture properties on the basis of a continuum fracture mechanics model for two different epoxy materials. Our approach reveals that the fracture energy of epoxy resins strongly depends on the functionality of epoxy resin and the component ratio between the curing agent (amine) and epoxide. The most intriguing part of our study is that we demonstrate that themore » fracture energy exhibits a maximum value within the range of conversion degrees considered (from 65% to 95%), which can be attributed to the combined effects of structural rigidity and post-yield deformability. Our study provides physical insight into the molecular mechanisms that govern the fracture characteristics of epoxy resins and demonstrates the success of utilizing atomistic molecular simulations towards predicting macroscopic material properties.« less

Fast scattering simulation tool for multi-energy x-ray imaging

NASA Astrophysics Data System (ADS)

Sossin, A.; Tabary, J.; Rebuffel, V.; Létang, J. M.; Freud, N.; Verger, L.

2015-12-01

A combination of Monte Carlo (MC) and deterministic approaches was employed as a means of creating a simulation tool capable of providing energy resolved x-ray primary and scatter images within a reasonable time interval. Libraries of Sindbad, a previously developed x-ray simulation software, were used in the development. The scatter simulation capabilities of the tool were validated through simulation with the aid of GATE and through experimentation by using a spectrometric CdTe detector. A simple cylindrical phantom with cavities and an aluminum insert was used. Cross-validation with GATE showed good agreement with a global spatial error of 1.5% and a maximum scatter spectrum error of around 6%. Experimental validation also supported the accuracy of the simulations obtained from the developed software with a global spatial error of 1.8% and a maximum error of around 8.5% in the scatter spectra.

Freud: a software suite for high-throughput simulation analysis

NASA Astrophysics Data System (ADS)

Harper, Eric; Spellings, Matthew; Anderson, Joshua; Glotzer, Sharon

Computer simulation is an indispensable tool for the study of a wide variety of systems. As simulations scale to fill petascale and exascale supercomputing clusters, so too does the size of the data produced, as well as the difficulty in analyzing these data. We present Freud, an analysis software suite for efficient analysis of simulation data. Freud makes no assumptions about the system being analyzed, allowing for general analysis methods to be applied to nearly any type of simulation. Freud includes standard analysis methods such as the radial distribution function, as well as new methods including the potential of mean force and torque and local crystal environment analysis. Freud combines a Python interface with fast, parallel C + + analysis routines to run efficiently on laptops, workstations, and supercomputing clusters. Data analysis on clusters reduces data transfer requirements, a prohibitive cost for petascale computing. Used in conjunction with simulation software, Freud allows for smart simulations that adapt to the current state of the system, enabling the study of phenomena such as nucleation and growth, intelligent investigation of phases and phase transitions, and determination of effective pair potentials.

Simulating the Response of a Composite Honeycomb Energy Absorber. Part 1; Dynamic Crushing of Components and Multi-Terrain Impacts

NASA Technical Reports Server (NTRS)

Jackson, Karen E.; Fasanella, Edwin L.; Polanco, Michael A.

2012-01-01

This paper describes the experimental and analytical evaluation of an externally deployable composite honeycomb structure that is designed to attenuate impact energy during helicopter crashes. The concept, designated the Deployable Energy Absorber (DEA), utilizes an expandable Kevlar (Registered Trademark) honeycomb to dissipate kinetic energy through crushing. The DEA incorporates a unique flexible hinge design that allows the honeycomb to be packaged and stowed until needed for deployment. Experimental evaluation of the DEA included dynamic crush tests of multi-cell components and vertical drop tests of a composite fuselage section, retrofitted with DEA blocks, onto multi-terrain. Finite element models of the test articles were developed and simulations were performed using the transient dynamic code, LSDYNA (Registered Trademark). In each simulation, the DEA was represented using shell elements assigned two different material properties: Mat 24, an isotropic piecewise linear plasticity model, and Mat 58, a continuum damage mechanics model used to represent laminated composite fabrics. DEA model development and test-analysis comparisons are presented.

Building Energy Monitoring and Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, Tianzhen; Feng, Wei; Lu, Alison

This project aimed to develop a standard methodology for building energy data definition, collection, presentation, and analysis; apply the developed methods to a standardized energy monitoring platform, including hardware and software, to collect and analyze building energy use data; and compile offline statistical data and online real-time data in both countries for fully understanding the current status of building energy use. This helps decode the driving forces behind the discrepancy of building energy use between the two countries; identify gaps and deficiencies of current building energy monitoring, data collection, and analysis; and create knowledge and tools to collect and analyzemore » good building energy data to provide valuable and actionable information for key stakeholders.« less

Analysis of energy resolution in the KURRI-LINAC pulsed neutron facility

NASA Astrophysics Data System (ADS)

Sano, Tadafumi; Hori, Jun-ichi; Takahashi, Yoshiyuki; Yashima, Hiroshi; Lee, Jaehong; Harada, Hideo

2017-09-01

In this study, we carried out Monte Carlo simulations to obtain the energy resolution of the neutron flux for TOF measurements in the KURRI-LINAC pulsed neutron facility. The simulation was performed on the moderated neutron flux from the pac-man type moderator at the energy range from 0.1 eV to 10 keV. As the result, we obtained the energy resolutions (ΔE/E) of about 0.7% to 1.3% between 0.1 eV to 10 keV. The energy resolution obtained from Monte Carlo simulation agreed with the resolution using the simplified evaluation formula. In addition, we compared the energy resolution among KURRI-LINAC and other TOF facilities, the energy dependency of the energy resolution with the pac-man type moderator in KURRI-LINAC was similar to the J-PARC ANNRI for the single-bunch mode.

Economic analysis of small wind-energy conversion systems

NASA Astrophysics Data System (ADS)

Haack, B. N.

1982-05-01

A computer simulation was developed for evaluating the economics of small wind energy conversion systems (SWECS). Input parameters consisted of initial capital investment, maintenance and operating costs, the cost of electricity from other sources, and the yield of electricity. Capital costs comprised the generator, tower, necessity for an inverter and/or storage batteries, and installation, in addition to interest on loans. Wind data recorded every three hours for one year in Detroit, MI was employed with a 0.16 power coefficient to extrapolate up to hub height as an example, along with 10 yr of use variances. A maximum return on investment was found to reside in using all the energy produced on site, rather than selling power to the utility. It is concluded that, based on a microeconomic analysis, SWECS are economically viable at present only where electric rates are inordinately high, such as in remote regions or on islands.

Kinematics analysis of vertical magnetic suspension energy storage flywheel rotor under transient rotational speed

NASA Astrophysics Data System (ADS)

Ren, Zhengyi; Huang, Tong; Feng, Jiajia; Zhou, Yuanwei

2018-05-01

In this paper, a 600Wh vertical maglev energy storage flywheel rotor system is taken as a model. The motion equation of a rigid rotor considering the gyroscopic effect and the center of mass offset is obtained by the centroid theorem, and the experimental verification is carried out. Using the state variable method, the Matlab software was used to program and simulate the radial displacement and radial electromagnetic force of the rotor system at each speed. The results show that the established system model is in accordance with the designed 600Wh vertical maglev energy storage flywheel model. The results of the simulation analysis are helpful to further understand the dynamic nature of the flywheel rotor at different transient speeds.

Simulation of energy- efficient building prototype using different insulating materials

NASA Astrophysics Data System (ADS)

Ouhaibi, Salma; Belouaggadia, Naoual; Lbibb, Rachid; Ezzine, Mohammed

2018-05-01

The objective of this work is to analyze the energetic efficiency of an individual building including an area of 130 m2 multi-zone, located in the region of FEZ which is characterized by a very hot and dry climate in summer and a quite cold one in winter, by incorporating insulating materials. This study was performed using TRNSYS V16 simulation software during a typical year of the FEZ region. Our simulation consists in developing a comparative study of two types of polystyrene and silica-aerogel insulation materials, in order to determine the best thermal performance. The results show that the thermal insulation of the building envelope is among the most effective solutions that give a significant reduction in energy requirements. Similarly, the use of silica-aerogels gives a good thermal performance, and therefore a good energy gain.

Wind Energy System Time-domain (WEST) analyzers using hybrid simulation techniques

NASA Technical Reports Server (NTRS)

Hoffman, J. A.

1979-01-01

Two stand-alone analyzers constructed for real time simulation of the complex dynamic characteristics of horizontal-axis wind energy systems are described. Mathematical models for an aeroelastic rotor, including nonlinear aerodynamic and elastic loads, are implemented with high speed digital and analog circuitry. Models for elastic supports, a power train, a control system, and a rotor gimbal system are also included. Limited correlation efforts show good comparisons between results produced by the analyzers and results produced by a large digital simulation. The digital simulation results correlate well with test data.

In situ and in-transit analysis of cosmological simulations

DOE PAGES

Friesen, Brian; Almgren, Ann; Lukic, Zarija; ...

2016-08-24

Modern cosmological simulations have reached the trillion-element scale, rendering data storage and subsequent analysis formidable tasks. To address this circumstance, we present a new MPI-parallel approach for analysis of simulation data while the simulation runs, as an alternative to the traditional workflow consisting of periodically saving large data sets to disk for subsequent ‘offline’ analysis. We demonstrate this approach in the compressible gasdynamics/N-body code Nyx, a hybrid MPI+OpenMP code based on the BoxLib framework, used for large-scale cosmological simulations. We have enabled on-the-fly workflows in two different ways: one is a straightforward approach consisting of all MPI processes periodically haltingmore » the main simulation and analyzing each component of data that they own (‘ in situ’). The other consists of partitioning processes into disjoint MPI groups, with one performing the simulation and periodically sending data to the other ‘sidecar’ group, which post-processes it while the simulation continues (‘in-transit’). The two groups execute their tasks asynchronously, stopping only to synchronize when a new set of simulation data needs to be analyzed. For both the in situ and in-transit approaches, we experiment with two different analysis suites with distinct performance behavior: one which finds dark matter halos in the simulation using merge trees to calculate the mass contained within iso-density contours, and another which calculates probability distribution functions and power spectra of various fields in the simulation. Both are common analysis tasks for cosmology, and both result in summary statistics significantly smaller than the original data set. We study the behavior of each type of analysis in each workflow in order to determine the optimal configuration for the different data analysis algorithms.« less

Energy-Systems Economic Analysis

NASA Technical Reports Server (NTRS)

Doane, J.; Slonski, M. L.; Borden, C. S.

1982-01-01

Energy Systems Economic Analysis (ESEA) program is flexible analytical tool for rank ordering of alternative energy systems. Basic ESEA approach derives an estimate of those costs incurred as result of purchasing, installing and operating an energy system. These costs, suitably aggregated into yearly costs over lifetime of system, are divided by expected yearly energy output to determine busbar energy costs. ESEA, developed in 1979, is written in FORTRAN IV for batch execution.

Simulation of energy-dependent electron diffusion processes in the Earth's outer radiation belt

DOE PAGES

Ma, Q.; Li, W.; Thorne, R. M.; ...

2016-04-28

The radial and local diffusion processes induced by various plasma waves govern the highly energetic electron dynamics in the Earth's radiation belts, causing distinct characteristics in electron distributions at various energies. In this study, we present our simulation results of the energetic electron evolution during a geomagnetic storm using the University of California, Los Angeles 3-D diffusion code. Following the plasma sheet electron injections, the electrons at different energy bands detected by the Magnetic Electron Ion Spectrometer (MagEIS) and Relativistic Electron Proton Telescope (REPT) instruments on board the Van Allen Probes exhibit a rapid enhancement followed by a slow diffusivemore » movement in differential energy fluxes, and the radial extent to which electrons can penetrate into depends on energy with closer penetration toward the Earth at lower energies than higher energies. We incorporate radial diffusion, local acceleration, and loss processes due to whistler mode wave observations to perform a 3-D diffusion simulation. Here, our simulation results demonstrate that chorus waves cause electron flux increase by more than 1 order of magnitude during the first 18 h, and the subsequent radial extents of the energetic electrons during the storm recovery phase are determined by the coupled radial diffusion and the pitch angle scattering by EMIC waves and plasmaspheric hiss. The radial diffusion caused by ULF waves and local plasma wave scattering are energy dependent, which lead to the observed electron flux variations with energy dependences. Lastly, this study suggests that plasma wave distributions in the inner magnetosphere are crucial for the energy-dependent intrusions of several hundred keV to several MeV electrons.« less

An expanded system simulation model for solar energy storage (technical report), volume 1

NASA Technical Reports Server (NTRS)

Warren, A. W.

1979-01-01

The simulation model for wind energy storage (SIMWEST) program now includes wind and/or photovoltaic systems utilizing any combination of five types of storage (pumped hydro, battery, thermal, flywheel and pneumatic) and is available for the UNIVAC 1100 series and the CDC 6000 series computers. The level of detail is consistent with a role of evaluating the economic feasibility as well as the general performance of wind and/or photovoltaic energy systems. The software package consists of two basic programs and a library of system, environmental, and load components. The first program is a precompiler which generates computer models (in FORTRAN) of complex wind and/or photovoltaic source/storage/application systems, from user specifications using the respective library components. The second program provides the techno-economic system analysis with the respective I/0, the integration of system dynamics, and the iteration for conveyance of variables.

Simulation of energy spectrum of GEM detector from an x-ray quantum

NASA Astrophysics Data System (ADS)

Malinowski, K.; Chernyshova, M.; Czarski, T.; Kowalska-Strzęciwilk, E.; Linczuk, P.; Wojeński, A.; Krawczyk, R.; Gąska, M.

2018-01-01

This paper presents the results of the energy resolution simulation for the triple GEM-based detector for x-ray quantum of 5.9 keV . Photons of this energy are emitted by 55Fe source, which is a standard calibration marker for this type of detectors. The calculations were made in Garfield++ in two stages. In the first stage, the distribution of the amount of primary electrons generated in the drift volume by the x-ray quantum was simulated using the Heed program. Secondly, the primary electrons of the resulting quantitative distribution were treated as a source of electron avalanches propagated through the whole volume of the triple GEM-based detector. The distribution of the obtained signals created a spectrum corresponding to the peak at 5.9 keV, which allowed us to determine the theoretical energy resolution of the detector. Its knowledge allows observing and improving the eventual experimental deterioration of the energy resolution, inevitably accompanying processes of registration and processing of the signals.

Energy-Water System Solutions | Energy Analysis | NREL

Science.gov Websites

simultaneously. Example Projects Energy, water, and renewable opportunities assessment at Bagram Air Force Base opportunity to plan integrated infrastructure. Example Projects Identification of critical water and campus-level opportunities. Example Projects Net Zero Energy-Water-Waste analysis for Fort Carson Net

Methodology for analysis and simulation of large multidisciplinary problems

NASA Technical Reports Server (NTRS)

Russell, William C.; Ikeda, Paul J.; Vos, Robert G.

1989-01-01

The Integrated Structural Modeling (ISM) program is being developed for the Air Force Weapons Laboratory and will be available for Air Force work. Its goal is to provide a design, analysis, and simulation tool intended primarily for directed energy weapons (DEW), kinetic energy weapons (KEW), and surveillance applications. The code is designed to run on DEC (VMS and UNIX), IRIS, Alliant, and Cray hosts. Several technical disciplines are included in ISM, namely structures, controls, optics, thermal, and dynamics. Four topics from the broad ISM goal are discussed. The first is project configuration management and includes two major areas: the software and database arrangement and the system model control. The second is interdisciplinary data transfer and refers to exchange of data between various disciplines such as structures and thermal. Third is a discussion of the integration of component models into one system model, i.e., multiple discipline model synthesis. Last is a presentation of work on a distributed processing computing environment.

An analysis of a low-energy, low-water use community in Mexico City

NASA Astrophysics Data System (ADS)

Bermudez Alcocer, Jose Luis

This study investigated how to determine a potential scenario to reduce energy, water and transportation use in Mexico City by implementing low-energy, low-water use communities. The proposed mixed-use community has multi-family apartments and a small grocery store. The research included the analysis of: case studies, energy simulation, and hand calculations for water, transportation and cost analysis. The previous case studies reviewed include: communities in Mexico City, Mexico, Austin, Texas, Phoenix, Arizona, New York City, New York and San Diego, California in terms of successful low-energy, low-water use projects. The analysis and comparison of these centers showed that the Multifamiliar Miguel Aleman is an excellent candidate to be examined for Mexico City. This technical potential study evaluated energy conserving measures such as low-energy appliances and efficient lighting that could be applied to the apartments in Mexico City to reduce energy-use. The use of the simulations and manual calculations showed that the application of the mixed-use concept was successful in reducing the energy and water use and the corresponding carbon footprint. Finally, this technical potential study showed taking people out of their cars as a result of the presence of the on-site grocery store, small recreation center and park on the ground floor also reduced their overall transportation energy-use. The improvement of the whole community (i.e., apartments plus grocery store) using energy-efficient measures provided a reduction of 70 percent of energy from the base-case. In addition a 69 percent reduction in water-use was achieved by using water-saving fixtures and greywater reuse technologies for the complex. The combination of high-efficiency automobiles and the presence of the on-site grocery store, small recreation center and park potentially reduced the transportation energy-use by 65 percent. The analysis showed an energy cost reduction of 82 percent reduction for

Calibrated energy simulations of potential energy savings in actual retail buildings

NASA Astrophysics Data System (ADS)

Alhafi, Zuhaira

Retail stores are commercial buildings with high energy consumption due to their typically large volumes and long hours of operation. This dissertation assesses heating, ventilating and air conditioning saving strategies based on energy simulations with input parameters from actual retail buildings. The dissertation hypothesis is that "Retail store buildings will save a significant amount of energy by (1) modifying ventilation rates, and/or (2) resetting set point temperatures. These strategies have shown to be beneficial in previous studies. As presented in the literature review, potential energy savings ranged from 0.5% to 30% without compromising indoor thermal comfort and indoor air quality. The retail store buildings can be ventilated at rates significantly lower than rates called for in the ASHRAE Standard 62.1-2010 while maintaining acceptable indoor air quality. Therefore, two dissertation objectives are addressed: (1) Investigate opportunities to reduce ventilation rates that do not compromise indoor air quality in retail stores located in Central Pennsylvania, (2) Investigate opportunities to increase (in summer) and decrease (in winter) set point temperatures that do not compromise thermal comfort. This study conducted experimental measurements of ventilation rates required to maintain acceptable air quality and indoor environmental conditions requirements for two retail stores using ASHRAE Standard 62.1_2012. More specifically, among other parameters, occupancy density, indoor and outdoor pollutant concentrations, and indoor temperatures were measured continuously for one week interval. One of these retail stores were tested four times for a yearlong time period. Pollutants monitored were formaldehyde, carbon dioxide, particle size distributions and concentrations, as well as total volatile organic compounds. As a part of the base protocol, the number of occupants in each store was hourly counted during the test, and the results reveal that the occupant

SRG110 Stirling Generator Dynamic Simulator Vibration Test Results and Analysis Correlation

NASA Technical Reports Server (NTRS)

Suarez, Vicente J.; Lewandowski, Edward J.; Callahan, John

2006-01-01

The U.S. Department of Energy (DOE), Lockheed Martin (LM), and NASA Glenn Research Center (GRC) have been developing the Stirling Radioisotope Generator (SRG110) for use as a power system for space science missions. The launch environment enveloping potential missions results in a random input spectrum that is significantly higher than historical RPS launch levels and is a challenge for designers. Analysis presented in prior work predicted that tailoring the compliance at the generator-spacecraft interface reduced the dynamic response of the system thereby allowing higher launch load input levels and expanding the range of potential generator missions. To confirm analytical predictions, a dynamic simulator representing the generator structure, Stirling convertors and heat sources was designed and built for testing with and without a compliant interface. Finite element analysis was performed to guide the generator simulator and compliant interface design so that test modes and frequencies were representative of the SRG110 generator. This paper presents the dynamic simulator design, the test setup and methodology, test article modes and frequencies and dynamic responses, and post-test analysis results. With the compliant interface, component responses to an input environment exceeding the SRG110 qualification level spectrum were all within design allowables. Post-test analysis included finite element model tuning to match test frequencies and random response analysis using the test input spectrum. Analytical results were in good overall agreement with the test results and confirmed previous predictions that the SRG110 power system may be considered for a broad range of potential missions, including those with demanding launch environments.

SRG110 Stirling Generator Dynamic Simulator Vibration Test Results and Analysis Correlation

NASA Technical Reports Server (NTRS)

Lewandowski, Edward J.; Suarez, Vicente J.; Goodnight, Thomas W.; Callahan, John

2007-01-01

The U.S. Department of Energy (DOE), Lockheed Martin (LM), and NASA Glenn Research Center (GRC) have been developing the Stirling Radioisotope Generator (SRG110) for use as a power system for space science missions. The launch environment enveloping potential missions results in a random input spectrum that is significantly higher than historical radioisotope power system (RPS) launch levels and is a challenge for designers. Analysis presented in prior work predicted that tailoring the compliance at the generator-spacecraft interface reduced the dynamic response of the system thereby allowing higher launch load input levels and expanding the range of potential generator missions. To confirm analytical predictions, a dynamic simulator representing the generator structure, Stirling convertors and heat sources were designed and built for testing with and without a compliant interface. Finite element analysis was performed to guide the generator simulator and compliant interface design so that test modes and frequencies were representative of the SRG110 generator. This paper presents the dynamic simulator design, the test setup and methodology, test article modes and frequencies and dynamic responses, and post-test analysis results. With the compliant interface, component responses to an input environment exceeding the SRG110 qualification level spectrum were all within design allowables. Post-test analysis included finite element model tuning to match test frequencies and random response analysis using the test input spectrum. Analytical results were in good overall agreement with the test results and confirmed previous predictions that the SRG110 power system may be considered for a broad range of potential missions, including those with demanding launch environments.

Sensitivity Analysis of Multidisciplinary Rotorcraft Simulations

NASA Technical Reports Server (NTRS)

Wang, Li; Diskin, Boris; Biedron, Robert T.; Nielsen, Eric J.; Bauchau, Olivier A.

2017-01-01

A multidisciplinary sensitivity analysis of rotorcraft simulations involving tightly coupled high-fidelity computational fluid dynamics and comprehensive analysis solvers is presented and evaluated. An unstructured sensitivity-enabled Navier-Stokes solver, FUN3D, and a nonlinear flexible multibody dynamics solver, DYMORE, are coupled to predict the aerodynamic loads and structural responses of helicopter rotor blades. A discretely-consistent adjoint-based sensitivity analysis available in FUN3D provides sensitivities arising from unsteady turbulent flows and unstructured dynamic overset meshes, while a complex-variable approach is used to compute DYMORE structural sensitivities with respect to aerodynamic loads. The multidisciplinary sensitivity analysis is conducted through integrating the sensitivity components from each discipline of the coupled system. Numerical results verify accuracy of the FUN3D/DYMORE system by conducting simulations for a benchmark rotorcraft test model and comparing solutions with established analyses and experimental data. Complex-variable implementation of sensitivity analysis of DYMORE and the coupled FUN3D/DYMORE system is verified by comparing with real-valued analysis and sensitivities. Correctness of adjoint formulations for FUN3D/DYMORE interfaces is verified by comparing adjoint-based and complex-variable sensitivities. Finally, sensitivities of the lift and drag functions obtained by complex-variable FUN3D/DYMORE simulations are compared with sensitivities computed by the multidisciplinary sensitivity analysis, which couples adjoint-based flow and grid sensitivities of FUN3D and FUN3D/DYMORE interfaces with complex-variable sensitivities of DYMORE structural responses.

Development of Residential Prototype Building Models and Analysis System for Large-Scale Energy Efficiency Studies Using EnergyPlus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mendon, Vrushali V.; Taylor, Zachary T.

ABSTRACT: Recent advances in residential building energy efficiency and codes have resulted in increased interest in detailed residential building energy models using the latest energy simulation software. One of the challenges of developing residential building models to characterize new residential building stock is to allow for flexibility to address variability in house features like geometry, configuration, HVAC systems etc. Researchers solved this problem in a novel way by creating a simulation structure capable of creating fully-functional EnergyPlus batch runs using a completely scalable residential EnergyPlus template system. This system was used to create a set of thirty-two residential prototype buildingmore » models covering single- and multifamily buildings, four common foundation types and four common heating system types found in the United States (US). A weighting scheme with detailed state-wise and national weighting factors was designed to supplement the residential prototype models. The complete set is designed to represent a majority of new residential construction stock. The entire structure consists of a system of utility programs developed around the core EnergyPlus simulation engine to automate the creation and management of large-scale simulation studies with minimal human effort. The simulation structure and the residential prototype building models have been used for numerous large-scale studies, one of which is briefly discussed in this paper.« less

Advanced statistical energy analysis

NASA Astrophysics Data System (ADS)

Heron, K. H.

1994-09-01

A high-frequency theory (advanced statistical energy analysis (ASEA)) is developed which takes account of the mechanism of tunnelling and uses a ray theory approach to track the power flowing around a plate or a beam network and then uses statistical energy analysis (SEA) to take care of any residual power. ASEA divides the energy of each sub-system into energy that is freely available for transfer to other sub-systems and energy that is fixed within the sub-systems that are physically separate and can be interpreted as a series of mathematical models, the first of which is identical to standard SEA and subsequent higher order models are convergent on an accurate prediction. Using a structural assembly of six rods as an example, ASEA is shown to converge onto the exact results while SEA is shown to overpredict by up to 60 dB.

Hourly test reference weather data in the changing climate of Finland for building energy simulations.

PubMed

Jylhä, Kirsti; Ruosteenoja, Kimmo; Jokisalo, Juha; Pilli-Sihvola, Karoliina; Kalamees, Targo; Mäkelä, Hanna; Hyvönen, Reijo; Drebs, Achim

2015-09-01

Dynamic building energy simulations need hourly weather data as input. The same high temporal resolution is required for assessments of future heating and cooling energy demand. The data presented in this article concern current typical values and estimated future changes in outdoor air temperature, wind speed, relative humidity and global, diffuse and normal solar radiation components. Simulated annual and seasonal delivered energy consumptions for heating of spaces, heating of ventilation supply air and cooling of spaces in the current and future climatic conditions are also presented for an example house, with district heating and a mechanical space cooling system. We provide details on how the synthetic future weather files were created and utilised as input data for dynamic building energy simulations by the IDA Indoor Climate and Energy program and also for calculations of heating and cooling degree-day sums. The information supplied here is related to the research article titled "Energy demand for the heating and cooling of residential houses in Finland in a changing climate" [1].

Equilibration and analysis of first-principles molecular dynamics simulations of water

NASA Astrophysics Data System (ADS)

Dawson, William; Gygi, François

2018-03-01

First-principles molecular dynamics (FPMD) simulations based on density functional theory are becoming increasingly popular for the description of liquids. In view of the high computational cost of these simulations, the choice of an appropriate equilibration protocol is critical. We assess two methods of estimation of equilibration times using a large dataset of first-principles molecular dynamics simulations of water. The Gelman-Rubin potential scale reduction factor [A. Gelman and D. B. Rubin, Stat. Sci. 7, 457 (1992)] and the marginal standard error rule heuristic proposed by White [Simulation 69, 323 (1997)] are evaluated on a set of 32 independent 64-molecule simulations of 58 ps each, amounting to a combined cumulative time of 1.85 ns. The availability of multiple independent simulations also allows for an estimation of the variance of averaged quantities, both within MD runs and between runs. We analyze atomic trajectories, focusing on correlations of the Kohn-Sham energy, pair correlation functions, number of hydrogen bonds, and diffusion coefficient. The observed variability across samples provides a measure of the uncertainty associated with these quantities, thus facilitating meaningful comparisons of different approximations used in the simulations. We find that the computed diffusion coefficient and average number of hydrogen bonds are affected by a significant uncertainty in spite of the large size of the dataset used. A comparison with classical simulations using the TIP4P/2005 model confirms that the variability of the diffusivity is also observed after long equilibration times. Complete atomic trajectories and simulation output files are available online for further analysis.

Equilibration and analysis of first-principles molecular dynamics simulations of water.

PubMed

Dawson, William; Gygi, François

2018-03-28

First-principles molecular dynamics (FPMD) simulations based on density functional theory are becoming increasingly popular for the description of liquids. In view of the high computational cost of these simulations, the choice of an appropriate equilibration protocol is critical. We assess two methods of estimation of equilibration times using a large dataset of first-principles molecular dynamics simulations of water. The Gelman-Rubin potential scale reduction factor [A. Gelman and D. B. Rubin, Stat. Sci. 7, 457 (1992)] and the marginal standard error rule heuristic proposed by White [Simulation 69, 323 (1997)] are evaluated on a set of 32 independent 64-molecule simulations of 58 ps each, amounting to a combined cumulative time of 1.85 ns. The availability of multiple independent simulations also allows for an estimation of the variance of averaged quantities, both within MD runs and between runs. We analyze atomic trajectories, focusing on correlations of the Kohn-Sham energy, pair correlation functions, number of hydrogen bonds, and diffusion coefficient. The observed variability across samples provides a measure of the uncertainty associated with these quantities, thus facilitating meaningful comparisons of different approximations used in the simulations. We find that the computed diffusion coefficient and average number of hydrogen bonds are affected by a significant uncertainty in spite of the large size of the dataset used. A comparison with classical simulations using the TIP4P/2005 model confirms that the variability of the diffusivity is also observed after long equilibration times. Complete atomic trajectories and simulation output files are available online for further analysis.

JASMINE: Data analysis and simulation

NASA Astrophysics Data System (ADS)

Yamada, Yoshiyuki; Gouda, Naoteru; Yano, Taihei; Kobayashi, Yukiyasu; Sako, Nobutada; Jasmine Working Group

JASMINE will study the structure and evolution of the Milky Way Galaxy. To accomplish these objectives JASMINE will measure trigonometric parallaxes, positions and proper motions of about 10 million stars with a precision of 10 μas at z = 14 mag. In this paper methods for data analysis and error budgets, on-board data handling such as sampling strategy and data compression, and simulation software for end-to-end simulation are presented.

Overcoming free energy barriers using unconstrained molecular dynamics simulations.

PubMed

Hénin, Jérôme; Chipot, Christophe

2004-08-15

Association of unconstrained molecular dynamics (MD) and the formalisms of thermodynamic integration and average force [Darve and Pohorille, J. Chem. Phys. 115, 9169 (2001)] have been employed to determine potentials of mean force. When implemented in a general MD code, the additional computational effort, compared to other standard, unconstrained simulations, is marginal. The force acting along a chosen reaction coordinate xi is estimated from the individual forces exerted on the chemical system and accumulated as the simulation progresses. The estimated free energy derivative computed for small intervals of xi is canceled by an adaptive bias to overcome the barriers of the free energy landscape. Evolution of the system along the reaction coordinate is, thus, limited by its sole self-diffusion properties. The illustrative examples of the reversible unfolding of deca-L-alanine, the association of acetate and guanidinium ions in water, the dimerization of methane in water, and its transfer across the water liquid-vapor interface are examined to probe the efficiency of the method. (c) 2004 American Institute of Physics.

Clean Energy Manufacturing Analysis Center (CEMAC)

DOE Office of Scientific and Technical Information (OSTI.GOV)

2015-12-01

The U.S. Department of Energy's Clean Energy Manufacturing Analysis Center (CEMAC) provides objective analysis and up-to-date data on global supply chains and manufacturing of clean energy technologies. Policymakers and industry leaders seek CEMAC insights to inform choices to promote economic growth and the transition to a clean energy economy.

Ultra-low frequency vibration data acquisition concerns in operating flight simulators. [Motion sickness inducing vibrations in flight simulators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Hoy, B.W.

1988-01-01

The measurement of ultra-low frequency vibration (.01 to 1.0 Hz) in motion based flight simulators was undertaken to quantify the energy and frequencies of motion present during operation. Methods of measurement, the selection of transducers, recorders, and analyzers and the development of a test plan, as well as types of analysis are discussed. Analysis of the data using a high-speed minicomputer and a comparison of the computer analysis with standard FFT analysis are also discussed. Measurement of simulator motion with the pilot included as part of the control dynamics had not been done up to this time. The data aremore » being used to evaluate the effect of low frequency energy on the vestibular system of the air crew, and the incidence of simulator induced sickness. 11 figs.« less

Energies and 2'-Hydroxyl Group Orientations of RNA Backbone Conformations. Benchmark CCSD(T)/CBS Database, Electronic Analysis, and Assessment of DFT Methods and MD Simulations.

PubMed

Mládek, Arnošt; Banáš, Pavel; Jurečka, Petr; Otyepka, Michal; Zgarbová, Marie; Šponer, Jiří

2014-01-14

Sugar-phosphate backbone is an electronically complex molecular segment imparting RNA molecules high flexibility and architectonic heterogeneity necessary for their biological functions. The structural variability of RNA molecules is amplified by the presence of the 2'-hydroxyl group, capable of forming multitude of intra- and intermolecular interactions. Bioinformatics studies based on X-ray structure database revealed that RNA backbone samples at least 46 substates known as rotameric families. The present study provides a comprehensive analysis of RNA backbone conformational preferences and 2'-hydroxyl group orientations. First, we create a benchmark database of estimated CCSD(T)/CBS relative energies of all rotameric families and test performance of dispersion-corrected DFT-D3 methods and molecular mechanics in vacuum and in continuum solvent. The performance of the DFT-D3 methods is in general quite satisfactory. The B-LYP-D3 method provides the best trade-off between accuracy and computational demands. B3-LYP-D3 slightly outperforms the new PW6B95-D3 and MPW1B95-D3 and is the second most accurate density functional of the study. The best agreement with CCSD(T)/CBS is provided by DSD-B-LYP-D3 double-hybrid functional, although its large-scale applications may be limited by high computational costs. Molecular mechanics does not reproduce the fine energy differences between the RNA backbone substates. We also demonstrate that the differences in the magnitude of the hyperconjugation effect do not correlate with the energy ranking of the backbone conformations. Further, we investigated the 2'-hydroxyl group orientation preferences. For all families, we conducted a QM and MM hydroxyl group rigid scan in gas phase and solvent. We then carried out set of explicit solvent MD simulations of folded RNAs and analyze 2'-hydroxyl group orientations of different backbone families in MD. The solvent energy profiles determined primarily by the sugar pucker match well with the

Testing and simulation of silicon photomultiplier readouts for scintillators in high-energy astronomy and solar physics

NASA Astrophysics Data System (ADS)

Bloser, P. F.; Legere, J. S.; Bancroft, C. M.; Jablonski, L. F.; Wurtz, J. R.; Ertley, C. D.; McConnell, M. L.; Ryan, J. M.

2014-11-01

the simulations. This discrepancy is likely due to the high input impedance of the readout board front-end electronics, which introduces a non-linear saturation effect in the SiPM for large light pulses. Analysis of the simulations indicates several additional steps that must be taken to optimize the energy resolution of SiPM-based scintillator detectors.

Simulations of neutron transport at low energy: a comparison between GEANT and MCNP.

PubMed

Colonna, N; Altieri, S

2002-06-01

The use of the simulation tool GEANT for neutron transport at energies below 20 MeV is discussed, in particular with regard to shielding and dose calculations. The reliability of the GEANT/MICAP package for neutron transport in a wide energy range has been verified by comparing the results of simulations performed with this package in a wide energy range with the prediction of MCNP-4B, a code commonly used for neutron transport at low energy. A reasonable agreement between the results of the two codes is found for the neutron flux through a slab of material (iron and ordinary concrete), as well as for the dose released in soft tissue by neutrons. These results justify the use of the GEANT/MICAP code for neutron transport in a wide range of applications, including health physics problems.

Transient analysis and energy optimization of solar heating and cooling systems in various configurations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Calise, F.; Dentice d'Accadia, M.; Palombo, A.

2010-03-15

In this paper, a transient simulation model of solar-assisted heating and cooling systems (SHC) is presented. A detailed case study is also discussed, in which three different configurations are considered. In all cases, the SHC system is based on the coupling of evacuated solar collectors with a single-stage LiBr-H{sub 2}O absorption chiller, and a gas-fired boiler is also included for auxiliary heating, only during the winter season. In the first configuration, the cooling capacity of the absorption chiller and the solar collector area are designed on the basis of the maximum cooling load, and an electric chiller is used asmore » the auxiliary cooling system. The second layout is similar to the first one, but, in this case, the absorption chiller and the solar collector area are sized in order to balance only a fraction of the maximum cooling load. Finally, in the third configuration, there is no electric chiller, and the auxiliary gas-fired boiler is also used in summer to feed the absorption chiller, in case of scarce solar irradiation. The simulation model was developed using the TRNSYS software, and included the analysis of the dynamic behaviour of the building in which the SHC systems were supposed to be installed. The building was simulated using a single-lumped capacitance model. An economic model was also developed, in order to assess the operating and capital costs of the systems under analysis. Furthermore, a mixed heuristic-deterministic optimization algorithm was implemented, in order to determine the set of the synthesis/design variables that maximize the energy efficiency of each configuration under analysis. The results of the case study were analyzed on monthly and weekly basis, paying special attention to the energy and monetary flows of the standard and optimized configurations. The results are encouraging as for the potential of energy saving. On the contrary, the SHC systems appear still far from the economic profitability: however, this is

Measurement and simulation of lineal energy distribution at the CERN high energy facility with a tissue equivalent proportional counter.

PubMed

Rollet, S; Autischer, M; Beck, P; Latocha, M

2007-01-01

The response of a tissue equivalent proportional counter (TEPC) in a mixed radiation field with a neutron energy distribution similar to the radiation field at commercial flight altitudes has been studied. The measurements have been done at the CERN-EU High-Energy Reference Field (CERF) facility where a well-characterised radiation field is available for intercomparison. The TEPC instrument used by the ARC Seibersdorf Research is filled with pure propane gas at low pressure and can be used to determine the lineal energy distribution of the energy deposition in a mass of gas equivalent to a 2 microm diameter volume of unit density tissue, of similar size to the nuclei of biological cells. The linearity of the detector response was checked both in term of dose and dose rate. The effect of dead-time has been corrected. The influence of the detector exposure location and orientation in the radiation field on the dose distribution was also studied as a function of the total dose. The microdosimetric distribution of the absorbed dose as a function of the lineal energy has been obtained and compared with the same distribution simulated with the FLUKA Monte Carlo transport code. The dose equivalent was calculated by folding this distribution with the quality factor as a function of linear energy transfer. The comparison between the measured and simulated distributions show that they are in good agreement. As a result of this study the detector is well characterised, thanks also to the numerical simulations the instrument response is well understood, and it's currently being used onboard the aircrafts to evaluate the dose to aircraft crew caused by cosmic radiation.

Molecular dynamics simulation of low-energy recoil events in titanate pyrochlores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Liyuan; Setyawan, Wahyu; Li, Yuhong

2017-01-01

Molecular dynamics simulations of low-energy displacements in titanate pyrochlores have been carried out along three main directions, to determineE dfor A, Ti and O, corresponding defect configurations, and defect formation dynamics.

Next-Generation Climate Modeling Science Challenges for Simulation, Workflow and Analysis Systems

NASA Astrophysics Data System (ADS)

Koch, D. M.; Anantharaj, V. G.; Bader, D. C.; Krishnan, H.; Leung, L. R.; Ringler, T.; Taylor, M.; Wehner, M. F.; Williams, D. N.

2016-12-01

We will present two examples of current and future high-resolution climate-modeling research that are challenging existing simulation run-time I/O, model-data movement, storage and publishing, and analysis. In each case, we will consider lessons learned as current workflow systems are broken by these large-data science challenges, as well as strategies to repair or rebuild the systems. First we consider the science and workflow challenges to be posed by the CMIP6 multi-model HighResMIP, involving around a dozen modeling groups performing quarter-degree simulations, in 3-member ensembles for 100 years, with high-frequency (1-6 hourly) diagnostics, which is expected to generate over 4PB of data. An example of science derived from these experiments will be to study how resolution affects the ability of models to capture extreme-events such as hurricanes or atmospheric rivers. Expected methods to transfer (using parallel Globus) and analyze (using parallel "TECA" software tools) HighResMIP data for such feature-tracking by the DOE CASCADE project will be presented. A second example will be from the Accelerated Climate Modeling for Energy (ACME) project, which is currently addressing challenges involving multiple century-scale coupled high resolution (quarter-degree) climate simulations on DOE Leadership Class computers. ACME is anticipating production of over 5PB of data during the next 2 years of simulations, in order to investigate the drivers of water cycle changes, sea-level-rise, and carbon cycle evolution. The ACME workflow, from simulation to data transfer, storage, analysis and publication will be presented. Current and planned methods to accelerate the workflow, including implementing run-time diagnostics, and implementing server-side analysis to avoid moving large datasets will be presented.

Advances in free-energy-based simulations of protein folding and ligand binding.

PubMed

Perez, Alberto; Morrone, Joseph A; Simmerling, Carlos; Dill, Ken A

2016-02-01

Free-energy-based simulations are increasingly providing the narratives about the structures, dynamics and biological mechanisms that constitute the fabric of protein science. Here, we review two recent successes. It is becoming practical: first, to fold small proteins with free-energy methods without knowing substructures and second, to compute ligand-protein binding affinities, not just their binding poses. Over the past 40 years, the timescales that can be simulated by atomistic MD are doubling every 1.3 years--which is faster than Moore's law. Thus, these advances are not simply due to the availability of faster computers. Force fields, solvation models and simulation methodology have kept pace with computing advancements, and are now quite good. At the tip of the spear recently are GPU-based computing, improved fast-solvation methods, continued advances in force fields, and conformational sampling methods that harness external information. Copyright © 2015 Elsevier Ltd. All rights reserved.

Molecular dynamics simulation and binding free energy studies of novel leads belonging to the benzofuran class inhibitors of Mycobacterium tuberculosis Polyketide Synthase 13.

PubMed

Cruz, Jorddy N; Costa, José F S; Khayat, André S; Kuca, Kamil; Barros, Carlos A L; Neto, A M J C

2018-05-04

In this work, the binding mechanism of new Polyketide Synthase 13 (Pks13) inhibitors has been studied through molecular dynamics simulation and free energy calculations. The drug Tam1 and its analogs, belonging to the benzofuran class, were submitted to 100 ns simulations, and according to the results obtained for root mean square deviation, all the simulations converged from approximately 30 ns. For the analysis of backbone flotation, the root mean square fluctuations were plotted for the Cα atoms; analysis revealed that the greatest fluctuation occurred in the residues that are part of the protein lid domain. The binding free energy value (ΔG bind ) obtained for the Tam16 lead molecule was of -51.43 kcal/mol. When comparing this result with the ΔG bind values for the remaining analogs, the drug Tam16 was found to be the highest ranked: this result is in agreement with the experimental results obtained by Aggarwal and collaborators, where it was verified that the IC 50 for Tam16 is the smallest necessary to inhibit the Pks13 (IC 50  = 0.19 μM). The energy decomposition analysis suggested that the residues which most interact with inhibitors are: Ser1636, Tyr1637, Asn1640, Ala1667, Phe1670, and Tyr1674, from which the greatest energy contribution to Phe1670 was particularly notable. For the lead molecule Tam16, a hydrogen bond with the hydroxyl of the phenol not observed in the other analogs induced a more stable molecular structure. Aggarwal and colleagues reported this hydrogen bonding as being responsible for the stability of the molecule, optimizing its physic-chemical, toxicological, and pharmacokinetic properties.

Cluster Free Energies from Simple Simulations of Small Numbers of Aggregants: Nucleation of Liquid MTBE from Vapor and Aqueous Phases.

PubMed

Patel, Lara A; Kindt, James T

2017-03-14

We introduce a global fitting analysis method to obtain free energies of association of noncovalent molecular clusters using equilibrated cluster size distributions from unbiased constant-temperature molecular dynamics (MD) simulations. Because the systems simulated are small enough that the law of mass action does not describe the aggregation statistics, the method relies on iteratively determining a set of cluster free energies that, using appropriately weighted sums over all possible partitions of N monomers into clusters, produces the best-fit size distribution. The quality of these fits can be used as an objective measure of self-consistency to optimize the cutoff distance that determines how clusters are defined. To showcase the method, we have simulated a united-atom model of methyl tert-butyl ether (MTBE) in the vapor phase and in explicit water solution over a range of system sizes (up to 95 MTBE in the vapor phase and 60 MTBE in the aqueous phase) and concentrations at 273 K. The resulting size-dependent cluster free energy functions follow a form derived from classical nucleation theory (CNT) quite well over the full range of cluster sizes, although deviations are more pronounced for small cluster sizes. The CNT fit to cluster free energies yielded surface tensions that were in both cases lower than those for the simulated planar interfaces. We use a simple model to derive a condition for minimizing non-ideal effects on cluster size distributions and show that the cutoff distance that yields the best global fit is consistent with this condition.

Impact Test and Simulation of Energy Absorbing Concepts for Earth Entry Vehicles

NASA Technical Reports Server (NTRS)

Billings, Marcus D.; Fasanella, Edwin L.; Kellas, Sotiris

2001-01-01

Nonlinear dynamic finite element simulations have been performed to aid in the design of an energy absorbing concept for a highly reliable passive Earth Entry Vehicle (EEV) that will directly impact the Earth without a parachute. EEV's are designed to return materials from asteroids, comets, or planets for laboratory analysis on Earth. The EEV concept uses an energy absorbing cellular structure designed to contain and limit the acceleration of space exploration samples during Earth impact. The spherical shaped cellular structure is composed of solid hexagonal and pentagonal foam-filled cells with hybrid graphite- epoxy/Kevlar cell walls. Space samples fit inside a smaller sphere at the center of the EEV's cellular structure. Comparisons of analytical predictions using MSC,Dytran with test results obtained from impact tests performed at NASA Langley Research Center were made for three impact velocities ranging from 32 to 40 m/s. Acceleration and deformation results compared well with the test results. These finite element models will be useful for parametric studies of off-nominal impact conditions.

Binding energies and modelling of nuclei in semiclassical simulations

NASA Astrophysics Data System (ADS)

Pérez-García, M. Ángeles; Tsushima, K.; Valcarce, A.

2008-03-01

We study the binding energies of spin isospin saturated nuclei with nucleon number 8⩽A⩽100 in semiclassical Monte Carlo many-body simulations. The model Hamiltonian consists of (i) nucleon kinetic energy, (ii) a nucleon nucleon interaction potential, and (iii) an effective Pauli potential which depends on density. The basic ingredients of the nucleon nucleon potential are a short-range repulsion, and a medium-range attraction. Our results demonstrate that one can always expect to obtain the empirical binding energies for a set of nuclei by introducing a proper density dependent Pauli potential in terms of a single variable, the nucleon number, A. The present work shows that in the suggested procedure there is a delicate counterbalance of kinetic and potential energetic contributions allowing a good reproduction of the experimental nuclear binding energies. This type of calculations may be of interest in further reproduction of other properties of nuclei such as radii and also exotic nuclei.

An Analysis of Home Energy Score and REM/Rate Energy Simulation Results for Homes in Three Climates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merket, Noel D

Energy ratings and scores for homes attempt to give homeowners a understandable metric to compare the energy efficiency of homes. Two rating systems in the marketplace include RESNET's Home Energy Rating System (HERS) and DOE's Home Energy Score (HEScore) and include differing energy calculation methodologies. This report compares the energy predictions from both REM/Rate and Home Energy Score for populations of real homes in three climates and determines some features of homes that lead to the greatest differences between energy predictions.

Energy consumption during simulated minimal access surgery with and without using an armrest.

PubMed

Jafri, Mansoor; Brown, Stuart; Arnold, Graham; Abboud, Rami; Wang, Weijie

2013-03-01

Minimal access surgery (MAS) can be a lengthy procedure when compared to open surgery and therefore surgeon fatigue becomes an important issue and surgeons may expose themselves to chronic injuries and making errors. There have been few studies on this topic and they have used only questionnaires and electromyography rather than direct measurement of energy expenditure (EE). The aim of this study was to investigate whether the use of an armrest could reduce the EE of surgeons during MAS. Sixteen surgeons performed simulated MAS with and without using an armrest. They were required to perform the time-consuming task of using scissors to cut a rubber glove through its top layer in a triangular fashion with the help of a laparoscopic camera. Energy consumptions were measured using the Oxycon Mobile system during all the procedures. Error rate and duration time for simulated surgery were recorded. After performing the simulated surgery, subjects scored how comfortable they felt using the armrest. It was found that O(2) uptake (VO(2)) was 5 % less when surgeons used the armrest. The error rate when performing the procedure with the armrest was 35 % compared with 42.29 % without the armrest. Additionally, comfort levels with the armrest were higher than without the armrest. 75 % of surgeons indicated a preference for using the armrest during the simulated surgery. The armrest provides support for surgeons and cuts energy consumption during simulated MAS.

Kinetic energy spectra, vertical resolution and dissipation in high-resolution atmospheric simulations.

NASA Astrophysics Data System (ADS)

Skamarock, W. C.

2017-12-01

We have performed week-long full-physics simulations with the MPAS global model at 15 km cell spacing using vertical mesh spacings of 800, 400, 200 and 100 meters in the mid-troposphere through the mid-stratosphere. We find that the horizontal kinetic energy spectra in the upper troposphere and stratosphere does not converge with increasing vertical resolution until we reach 200 meter level spacing. Examination of the solutions indicates that significant inertia-gravity waves are not vertically resolved at the lower vertical resolutions. Diagnostics from the simulations indicate that the primary kinetic energy dissipation results from the vertical mixing within the PBL parameterization and from the gravity-wave drag parameterization, with smaller but significant contributions from damping in the vertical transport scheme and from the horizontal filters in the dynamical core. Most of the kinetic energy dissipation in the free atmosphere occurs within breaking mid-latitude baroclinic waves. We will briefly review these results and their implications for atmospheric model configuration and for atmospheric dynamics, specifically that related to the dynamics associated with the mesoscale kinetic energy spectrum.

Analysis of Voyager Observed High-Energy Electron Fluxes in the Heliosheath Using MHD Simulations

NASA Technical Reports Server (NTRS)

Washimi, Haruichi; Webber, W. R.; Zank, Gary P.; Hu, Qiang; Florinski, Vladimir; Adams, James; Kubo, Yuki

2011-01-01

The Voyager spacecraft (V1 and V2) observed electrons of 6-14 MeV in the heliosheath which showed several incidences of flux variation relative to a background of gradually increasing flux with distance from the Sun. The increasing flux of background electrons is thought to result from inward radial diffusion. We compare the temporal electron flux variation with dynamical phenomena in the heliosheath that are obtained from our MHD simulations. Because our simulation is based on V2 observed plasma data before V2 crossed the termination shock, this analysis is effective up to late 2008, i.e., about a year after the V2-crossing, during which disturbances, driven prior to the crossing time, survived in the heliosheath. Several electron flux variations correspond to times directly associated with interplanetary shock events. One noteworthy example corresponds to various times associated with the March 2006 interplanetary shock, these being the collision with the termination shock, the passage past the V1 spacecraft, and the collision with the region near the heliopause, as identified by W.R. Webber et al. for proton/helium of 7-200 MeV. Our simulations indicate that all other electron flux variations, except one, correspond well to the times when a shock-driven magneto-sonic pulse and its reflection in the heliosheath either passed across V1/V2, or collided with the termination shock or with the plasma sheet near the heliopause. This result suggests that variation in the electron flux should be due to either direct or indirect effects of magnetosonic pulses in the heliosheath driven by interplanetary shocks

Advanced Coupled Simulation of Borehole Thermal Energy Storage Systems and Above Ground Installations

NASA Astrophysics Data System (ADS)

Welsch, Bastian; Rühaak, Wolfram; Schulte, Daniel O.; Bär, Kristian; Sass, Ingo

2016-04-01

Seasonal thermal energy storage in borehole heat exchanger arrays is a promising technology to reduce primary energy consumption and carbon dioxide emissions. These systems usually consist of several subsystems like the heat source (e.g. solarthermics or a combined heat and power plant), the heat consumer (e.g. a heating system), diurnal storages (i.e. water tanks), the borehole thermal energy storage, additional heat sources for peak load coverage (e.g. a heat pump or a gas boiler) and the distribution network. For the design of an integrated system, numerical simulations of all subsystems are imperative. A separate simulation of the borehole energy storage is well-established but represents a simplification. In reality, the subsystems interact with each other. The fluid temperatures of the heat generation system, the heating system and the underground storage are interdependent and affect the performance of each subsystem. To take into account these interdependencies, we coupled a software for the simulation of the above ground facilities with a finite element software for the modeling of the heat flow in the subsurface and the borehole heat exchangers. This allows for a more realistic view on the entire system. Consequently, a finer adjustment of the system components and a more precise prognosis of the system's performance can be ensured.

Distributed energy store railguns experiment and analysis

NASA Astrophysics Data System (ADS)

Holland, L. D.

1984-02-01

Electromagnetic acceleration of projectiles holds the potential for achieving higher velocities than yet achieved by any other means. A railgun is the simplest form of electromagnetic macroparticle accelerator and can generate the highest sustained accelerating force. The practical length of conventional railguns is limited by the impedance of the rails because current must be carried along the entire length of the rails. A railgun and power supply system called the distributed energy store railgun was proposed as a solution to this limitation. A distributed energy storage railgun was constructed and successfully operated. In addition to this demonstration of the distributed energy store railgun principle, a theoretical model of the system was also constructed. A simple simulation of the railgun system based on this model, but ignoring frictional drag, was compared with the experimental results. During the process of comparing results from the simulation and the experiment, the effect of significant frictional drag of the projectile on the sidewalls of the bore was observed.

Rapid Convergence of Energy and Free Energy Profiles with Quantum Mechanical Size in Quantum Mechanical-Molecular Mechanical Simulations of Proton Transfer in DNA.

PubMed

Das, Susanta; Nam, Kwangho; Major, Dan Thomas

2018-03-13

In recent years, a number of quantum mechanical-molecular mechanical (QM/MM) enzyme studies have investigated the dependence of reaction energetics on the size of the QM region using energy and free energy calculations. In this study, we revisit the question of QM region size dependence in QM/MM simulations within the context of energy and free energy calculations using a proton transfer in a DNA base pair as a test case. In the simulations, the QM region was treated with a dispersion-corrected AM1/d-PhoT Hamiltonian, which was developed to accurately describe phosphoryl and proton transfer reactions, in conjunction with an electrostatic embedding scheme using the particle-mesh Ewald summation method. With this rigorous QM/MM potential, we performed rather extensive QM/MM sampling, and found that the free energy reaction profiles converge rapidly with respect to the QM region size within ca. ±1 kcal/mol. This finding suggests that the strategy of QM/MM simulations with reasonably sized and selected QM regions, which has been employed for over four decades, is a valid approach for modeling complex biomolecular systems. We point to possible causes for the sensitivity of the energy and free energy calculations to the size of the QM region, and potential implications.

Kinematics of Globular Cluster: new Perspectives of Energy Equipartition from N-body Simulations

NASA Astrophysics Data System (ADS)

Kim, Hyunwoo; Pasquato, Mario; Yoon, Suk-jin

2018-01-01

Globular clusters (GCs) evolve dynamically through gravitational two-body interactions between stars. We investigated the evolution towards energy equipartition in GCs using direct n-body simulations in NBODY6. If a GC reaches full energy equipartition, the velocity dispersion as a function of stars’ mass becomes a power law with exponent -1/2. However, our n-body simulations never reach full equipartition, which is similar to Trenti & van de Marel (2013) results. Instead we found that in simulations with a shallow mass spectrum the best fit exponent becomes positive slightly before core collapse time. This inversion is a new result, which can be used as a kinematic predictor of core collapse. We are currently exploring applications of this inversion indicator to the detection of intermediate mass black holes.

Air source integrated heat pump simulation model for EnergyPlus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Bo; New, Joshua; Baxter, Van

An Air Source Integrated Heat Pump (AS-IHP) is an air source, multi-functional spacing conditioning unit with water heating function (WH), which can lead to great energy savings by recovering the condensing waste heat for domestic water heating. This paper summarizes development of the EnergyPlus AS-IHP model, introducing the physics, sub-models, working modes, and control logic. Based on the model, building energy simulations were conducted to demonstrate greater than 50% annual energy savings, in comparison to a baseline heat pump with electric water heater, over 10 US cities, using the EnergyPlus quick-service restaurant template building. We assessed water heating energy savingmore » potentials using AS-IHP versus both gas and electric baseline systems, and pointed out climate zones where AS-IHPs are promising. In addition, a grid integration strategy was investigated to reveal further energy saving and electricity cost reduction potentials, via increasing the water heating set point temperature during off-peak hours and using larger water tanks.« less

LENS: μLENS Simulations, Analysis, and Results

NASA Astrophysics Data System (ADS)

Rasco, Charles

2013-04-01

Simulations of the Low-Energy Neutrino Spectrometer prototype, μLENS, have been performed in order to benchmark the first measurements of the μLENS detector at the Kimballton Underground Research Facility (KURF). μLENS is a 6x6x6 celled scintillation lattice filled with Linear Alkylbenzene based scintillator. We have performed simulations of μLENS using the GEANT4 toolkit. We have measured various radioactive sources, LEDs, and environmental background radiation measurements at KURF using up to 96 PMTs with a simplified data acquisition system of QDCs and TDCs. In this talk we will demonstrate our understanding of the light propagation and we will compare simulation results with measurements of the μLENS detector of various radioactive sources, LEDs, and the environmental background radiation.

Analysis of the economics of photovoltaic-diesel-battery energy systems for remote applications

NASA Technical Reports Server (NTRS)

Brainard, W. A.

1983-01-01

Computer simulations were conducted to analyze the performance and operating cost of a photovoltaic energy source combined with a diesel generator system and battery storage. The simulations were based on the load demand profiles used for the design of an all photovoltaic energy system installed in the remote Papago Indian Village of Schuchuli, Arizona. Twenty year simulations were run using solar insolation data from Phoenix SOLMET tapes. Total energy produced, energy consumed, operation and maintenance costs were calculated. The life cycle and levelized energy costs were determined for a variety of system configurations (i.e., varying amounts of photovoltaic array and battery storage).

Simulating and validating coastal gradients in wind energy resources

NASA Astrophysics Data System (ADS)

Hahmann, Andrea; Floors, Rogier; Karagali, Ioanna; Vasiljevic, Nikola; Lea, Guillaume; Simon, Elliot; Courtney, Michael; Badger, Merete; Peña, Alfredo; Hasager, Charlotte

2016-04-01

The experimental campaign of the RUNE (Reducing Uncertainty of Near-shore wind resource Estimates) project took place on the western coast of Denmark during the winter 2015-2016. The campaign used onshore scanning lidar technology combined with ocean and satellite information and produced a unique dataset to study the transition in boundary layer dynamics across the coastal zone. The RUNE project aims at reducing the uncertainty of near-shore wind resource estimates produced by mesoscale modeling. With this in mind, simulations using the Weather Research and Forecasting (WRF) model were performed to identify the sensitivity in the coastal gradients of wind energy resources to various model parameters and model inputs. Among these: model horizontal grid spacing and the planetary boundary layer and surface-layer scheme. We report on the differences amongst these simulations and preliminary results on the comparison of the model simulations with the RUNE observations of lidar and satellite measurements and near coastal tall mast.

Analysis of the Space Shuttle main engine simulation

NASA Technical Reports Server (NTRS)

Deabreu-Garcia, J. Alex; Welch, John T.

1993-01-01

This is a final report on an analysis of the Space Shuttle Main Engine Program, a digital simulator code written in Fortran. The research was undertaken in ultimate support of future design studies of a shuttle life-extending Intelligent Control System (ICS). These studies are to be conducted by NASA Lewis Space Research Center. The primary purpose of the analysis was to define the means to achieve a faster running simulation, and to determine if additional hardware would be necessary for speeding up simulations for the ICS project. In particular, the analysis was to consider the use of custom integrators based on the Matrix Stability Region Placement (MSRP) method. In addition to speed of execution, other qualities of the software were to be examined. Among these are the accuracy of computations, the useability of the simulation system, and the maintainability of the program and data files. Accuracy involves control of truncation error of the methods, and roundoff error induced by floating point operations. It also involves the requirement that the user be fully aware of the model that the simulator is implementing.

Effects of 3D Virtual Simulators in the Introductory Wind Energy Course: A Tool for Teaching Engineering Concepts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Do, Phuong T.; Moreland, John R.; Delgado, Catherine

Our research provides an innovative solution for optimizing learning effectiveness and improving postsecondary education through the development of virtual simulators that can be easily used and integrated into existing wind energy curriculum. Two 3D virtual simulators are developed in our laboratory for use in an immersive 3D virtual reality (VR) system or for 3D display on a 2D screen. Our goal is to apply these prototypical simulators to train postsecondary students and professionals in wind energy education; and to offer experiential learning opportunities in 3D modeling, simulation, and visualization. The issue of transferring learned concepts to practical applications is amore » widespread problem in postsecondary education. Related to this issue is a critical demand to educate and train a generation of professionals for the wind energy industry. With initiatives such as the U.S. Department of Energy's “20% Wind Energy by 2030” outlining an exponential increase of wind energy capacity over the coming years, revolutionary educational reform is needed to meet the demand for education in the field of wind energy. These developments and implementation of Virtual Simulators and accompanying curriculum will propel national reforms, meeting the needs of the wind energy industrial movement and addressing broader educational issues that affect a number of disciplines.« less

Effects of 3D Virtual Simulators in the Introductory Wind Energy Course: A Tool for Teaching Engineering Concepts

DOE PAGES

Do, Phuong T.; Moreland, John R.; Delgado, Catherine; ...

2013-01-01

Our research provides an innovative solution for optimizing learning effectiveness and improving postsecondary education through the development of virtual simulators that can be easily used and integrated into existing wind energy curriculum. Two 3D virtual simulators are developed in our laboratory for use in an immersive 3D virtual reality (VR) system or for 3D display on a 2D screen. Our goal is to apply these prototypical simulators to train postsecondary students and professionals in wind energy education; and to offer experiential learning opportunities in 3D modeling, simulation, and visualization. The issue of transferring learned concepts to practical applications is amore » widespread problem in postsecondary education. Related to this issue is a critical demand to educate and train a generation of professionals for the wind energy industry. With initiatives such as the U.S. Department of Energy's “20% Wind Energy by 2030” outlining an exponential increase of wind energy capacity over the coming years, revolutionary educational reform is needed to meet the demand for education in the field of wind energy. These developments and implementation of Virtual Simulators and accompanying curriculum will propel national reforms, meeting the needs of the wind energy industrial movement and addressing broader educational issues that affect a number of disciplines.« less

Application of a forest-simulation model to assess the energy yield and ecological impact of forest utilization for energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doyle, T W; Shugart, H H; West, D C

1981-01-01

This study examines the utilization and management of natural forest lands to meet growing wood-energy demands. An application of a forest simulation model is described for assessing energy returns and long-term ecological impacts of wood-energy harvesting under four general silvicultural practices. Results indicate that moderate energy yields could be expected from mild cutting operations which would significantly effect neither the commercial timber market nor the composition, structure, or diversity of these forests. Forest models can provide an effective tool for determining optimal management strategies that maximize energy returns, minimize environmental detriment, and complement existing land-use plans.

A piezoelectric six-DOF vibration energy harvester based on parallel mechanism: dynamic modeling, simulation, and experiment

NASA Astrophysics Data System (ADS)

Yuan, G.; Wang, D. H.

2017-03-01

Multi-directional and multi-degree-of-freedom (multi-DOF) vibration energy harvesting are attracting more and more research interest in recent years. In this paper, the principle of a piezoelectric six-DOF vibration energy harvester based on parallel mechanism is proposed to convert the energy of the six-DOF vibration to single-DOF vibrations of the limbs on the energy harvester and output voltages. The dynamic model of the piezoelectric six-DOF vibration energy harvester is established to estimate the vibrations of the limbs. On this basis, a Stewart-type piezoelectric six-DOF vibration energy harvester is developed and explored. In order to validate the established dynamic model and the analysis results, the simulation model of the Stewart-type piezoelectric six-DOF vibration energy harvester is built and tested with different vibration excitations by SimMechanics, and some preliminary experiments are carried out. The results show that the vibration of the limbs on the piezoelectric six-DOF vibration energy harvester can be estimated by the established dynamic model. The developed Stewart-type piezoelectric six-DOF vibration energy harvester can harvest the energy of multi-directional linear vibration and multi-axis rotating vibration with resonance frequencies of 17 Hz, 25 Hz, and 47 Hz. Moreover, the resonance frequencies of the developed piezoelectric six-DOF vibration energy harvester are not affected by the direction changing of the vibration excitation.

Development of a Platform for Simulating and Optimizing Thermoelectric Energy Systems

NASA Astrophysics Data System (ADS)

Kreuder, John J.

Thermoelectrics are solid state devices that can convert thermal energy directly into electrical energy. They have historically been used only in niche applications because of their relatively low efficiencies. With the advent of nanotechnology and improved manufacturing processes thermoelectric materials have become less costly and more efficient As next generation thermoelectric materials become available there is a need for industries to quickly and cost effectively seek out feasible applications for thermoelectric heat recovery platforms. Determining the technical and economic feasibility of such systems requires a model that predicts performance at the system level. Current models focus on specific system applications or neglect the rest of the system altogether, focusing on only module design and not an entire energy system. To assist in screening and optimizing entire energy systems using thermoelectrics, a novel software tool, Thermoelectric Power System Simulator (TEPSS), is developed for system level simulation and optimization of heat recovery systems. The platform is designed for use with a generic energy system so that most types of thermoelectric heat recovery applications can be modeled. TEPSS is based on object-oriented programming in MATLABRTM. A modular, shell based architecture is developed to carry out concept generation, system simulation and optimization. Systems are defined according to the components and interconnectivity specified by the user. An iterative solution process based on Newton's Method is employed to determine the system's steady state so that an objective function representing the cost of the system can be evaluated at the operating point. An optimization algorithm from MATLAB's Optimization Toolbox uses sequential quadratic programming to minimize this objective function with respect to a set of user specified design variables and constraints. During this iterative process many independent system simulations are executed and

Fault Gauge Numerical Simulation : Dynamic Rupture Propagation and Local Energy Partitioning

NASA Astrophysics Data System (ADS)

Mollon, G.

2017-12-01

In this communication, we present dynamic simulations of the local (centimetric) behaviour of a fault filled with a granular gauge submitted to dynamic rupture. The numerical tool (Fig. 1) combines classical Discrete Element Modelling (albeit with the ability to deal with arbitrary grain shapes) for the simualtion of the gauge, and continuous modelling for the simulation of the acoustic waves emission and propagation. In a first part, the model is applied to the simulation of steady-state shearing of the fault under remote displacement boudary conditions, in order to observe the shear accomodation at the interface (R1 cracks, localization, wear, etc.). It also makes it possible to fit to desired values the Rate and State Friction properties of the granular gauge by adapting the contact laws between grains. Such simulations provide quantitative insight in the steady-state energy partitionning between fracture, friction and acoustic emissions as a function of the shear rate. In a second part, the model is submitted to dynamic rupture. For that purpose, the fault is elastically preloaded just below rupture, and a displacement pulse is applied at one end of the sample (and on only one side of the fault). This allows to observe the propagation of the instability along the fault and the interplay between this propagation and the local granular phenomena. Energy partitionning is then observed both in space and time.

How to Run FAST Simulations.

PubMed

Zimmerman, M I; Bowman, G R

2016-01-01

Molecular dynamics (MD) simulations are a powerful tool for understanding enzymes' structures and functions with full atomistic detail. These physics-based simulations model the dynamics of a protein in solution and store snapshots of its atomic coordinates at discrete time intervals. Analysis of the snapshots from these trajectories provides thermodynamic and kinetic properties such as conformational free energies, binding free energies, and transition times. Unfortunately, simulating biologically relevant timescales with brute force MD simulations requires enormous computing resources. In this chapter we detail a goal-oriented sampling algorithm, called fluctuation amplification of specific traits, that quickly generates pertinent thermodynamic and kinetic information by using an iterative series of short MD simulations to explore the vast depths of conformational space. © 2016 Elsevier Inc. All rights reserved.

Measurement and Simulation of the Variation in Proton-Induced Energy Deposition in Large Silicon Diode Arrays

NASA Technical Reports Server (NTRS)

Howe, Christina L.; Weller, Robert A.; Reed, Robert A.; Sierawski, Brian D.; Marshall, Paul W.; Marshall, Cheryl J.; Mendenhall, Marcus H.; Schrimpf, Ronald D.

2007-01-01

The proton induced charge deposition in a well characterized silicon P-i-N focal plane array is analyzed with Monte Carlo based simulations. These simulations include all physical processes, together with pile up, to accurately describe the experimental data. Simulation results reveal important high energy events not easily detected through experiment due to low statistics. The effects of each physical mechanism on the device response is shown for a single proton energy as well as a full proton space flux.

Analysis of local warm forming of high strength steel using near infrared ray energy

NASA Astrophysics Data System (ADS)

Yang, W. H.; Lee, K.; Lee, E. H.; Yang, D. Y.

2013-12-01

The automotive industry has been pressed to satisfy more rigorous fuel efficiency requirements to promote energy conservation, safety features and cost containment. To satisfy this need, high strength steel has been developed and used for many different vehicle parts. The use of high strength steels, however, requires careful analysis and creativity in order to accommodate its relatively high springback behavior. An innovative method, called local warm forming with near infrared ray, has been developed to help promote the use of high strength steels in sheet metal forming. For this method, local regions of the work piece are heated using infrared ray energy, thereby promoting the reduction of springback behavior. In this research, a V-bend test is conducted with DP980. After springback, the bend angles for specimens without local heating are compared to those with local heating. Numerical analysis has been performed using the commercial program, DEFORM-2D. This analysis is carried out with the purpose of understanding how changes to the local stress distribution will affect the springback during the unloading process. The results between experimental and computational approaches are evaluated to assure the accuracy of the simulation. Subsequent numerical simulation studies are performed to explore best practices with respect to thermal boundary conditions, timing, and applicability to the production environment.

Workshop on data acquisition and trigger system simulations for high energy physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1992-12-31

This report discusses the following topics: DAQSIM: A data acquisition system simulation tool; Front end and DCC Simulations for the SDC Straw Tube System; Simulation of Non-Blocklng Data Acquisition Architectures; Simulation Studies of the SDC Data Collection Chip; Correlation Studies of the Data Collection Circuit & The Design of a Queue for this Circuit; Fast Data Compression & Transmission from a Silicon Strip Wafer; Simulation of SCI Protocols in Modsim; Visual Design with vVHDL; Stochastic Simulation of Asynchronous Buffers; SDC Trigger Simulations; Trigger Rates, DAQ & Online Processing at the SSC; Planned Enhancements to MODSEM II & SIMOBJECT -- anmore » Overview -- R.; DAGAR -- A synthesis system; Proposed Silicon Compiler for Physics Applications; Timed -- LOTOS in a PROLOG Environment: an Algebraic language for Simulation; Modeling and Simulation of an Event Builder for High Energy Physics Data Acquisition Systems; A Verilog Simulation for the CDF DAQ; Simulation to Design with Verilog; The DZero Data Acquisition System: Model and Measurements; DZero Trigger Level 1.5 Modeling; Strategies Optimizing Data Load in the DZero Triggers; Simulation of the DZero Level 2 Data Acquisition System; A Fast Method for Calculating DZero Level 1 Jet Trigger Properties and Physics Input to DAQ Studies.« less

Simulation model of stratified thermal energy storage tank using finite difference method

NASA Astrophysics Data System (ADS)

Waluyo, Joko

2016-06-01

Stratified TES tank is normally used in the cogeneration plant. The stratified TES tanks are simple, low cost, and equal or superior in thermal performance. The advantage of TES tank is that it enables shifting of energy usage from off-peak demand for on-peak demand requirement. To increase energy utilization in a stratified TES tank, it is required to build a simulation model which capable to simulate the charging phenomenon in the stratified TES tank precisely. This paper is aimed to develop a novel model in addressing the aforementioned problem. The model incorporated chiller into the charging of stratified TES tank system in a closed system. The model was developed in one-dimensional type involve with heat transfer aspect. The model covers the main factors affect to degradation of temperature distribution namely conduction through the tank wall, conduction between cool and warm water, mixing effect on the initial flow of the charging as well as heat loss to surrounding. The simulation model is developed based on finite difference method utilizing buffer concept theory and solved in explicit method. Validation of the simulation model is carried out using observed data obtained from operating stratified TES tank in cogeneration plant. The temperature distribution of the model capable of representing S-curve pattern as well as simulating decreased charging temperature after reaching full condition. The coefficient of determination values between the observed data and model obtained higher than 0.88. Meaning that the model has capability in simulating the charging phenomenon in the stratified TES tank. The model is not only capable of generating temperature distribution but also can be enhanced for representing transient condition during the charging of stratified TES tank. This successful model can be addressed for solving the limitation temperature occurs in charging of the stratified TES tank with the absorption chiller. Further, the stratified TES tank can be

San Carlos Apache Tribe - Energy Organizational Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rapp, James; Albert, Steve

2012-04-01

The San Carlos Apache Tribe (SCAT) was awarded $164,000 in late-2011 by the U.S. Department of Energy (U.S. DOE) Tribal Energy Program's "First Steps Toward Developing Renewable Energy and Energy Efficiency on Tribal Lands" Grant Program. This grant funded:  The analysis and selection of preferred form(s) of tribal energy organization (this Energy Organization Analysis, hereinafter referred to as "EOA").  Start-up staffing and other costs associated with the Phase 1 SCAT energy organization.  An intern program.  Staff training.  Tribal outreach and workshops regarding the new organization and SCAT energy programs and projects, including two annual tribalmore » energy summits (2011 and 2012). This report documents the analysis and selection of preferred form(s) of a tribal energy organization.« less

In-Depth Analysis of Simulation Engine Codes for Comparison with DOE s Roof Savings Calculator and Measured Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

New, Joshua Ryan; Levinson, Ronnen; Huang, Yu

The Roof Savings Calculator (RSC) was developed through collaborations among Oak Ridge National Laboratory (ORNL), White Box Technologies, Lawrence Berkeley National Laboratory (LBNL), and the Environmental Protection Agency in the context of a California Energy Commission Public Interest Energy Research project to make cool-color roofing materials a market reality. The RSC website and a simulation engine validated against demonstration homes were developed to replace the liberal DOE Cool Roof Calculator and the conservative EPA Energy Star Roofing Calculator, which reported different roof savings estimates. A preliminary analysis arrived at a tentative explanation for why RSC results differed from previous LBNLmore » studies and provided guidance for future analysis in the comparison of four simulation programs (doe2attic, DOE-2.1E, EnergyPlus, and MicroPas), including heat exchange between the attic surfaces (principally the roof and ceiling) and the resulting heat flows through the ceiling to the building below. The results were consolidated in an ORNL technical report, ORNL/TM-2013/501. This report is an in-depth inter-comparison of four programs with detailed measured data from an experimental facility operated by ORNL in South Carolina in which different segments of the attic had different roof and attic systems.« less

NIMROD Simulations of Spheromak Formation, Magnetic Reconnection and Energy Confinement in SSPX

NASA Astrophysics Data System (ADS)

Hooper, E. B.; Sovinec, C. R.

2005-10-01

The SSPX spheromak is formed and driven by a coaxial electrostatic gun that injects current and magnetic flux. Magnetic fluctuations are associated with the conversion of toroidal to poloidal magnetic flux during formation. After formation, fluctuations that break axisymmetry degrade magnetic surfaces, and are anti-correlated with the core temperature and energy confinement time. We report NIMROD simulations extending earlier work^1 supporting the SSPX experiment through predictions of performance and providing insight. The simulations are in fairly good agreement with features observed in SSPX and underscore the importance of current profile control in mitigating magnetic fluctuation amplitudes and improving confinement. The simulations yield insight into magnetic reconnection and the relationship of fluctuations to field line stochasticity. We have added external circuit equations for the new 32 module capacitor bank in SSPX that will add flexibility in shaping the injector current pulses and substantially increase the injected currents and the magnetic energy. New NIMROD simulations of SSPX lead to higher temperature plasmas than in previous simulations. *Work supported by U.S. DOE, under Contr. No. W-7405-ENG-48 at U. Cal. LLNL and under grant FG02-01ER54661 at U. Wisc Madison. ^1C. R. Sovinec, B. I. Cohen, et al., Phys. Rev. Lett. 94, 035003 (2005); B. I. Cohen, E. B. Hooper, et al., Phys. Plasmas 12, 056106 (2005).

Cloud-radiative effects on implied oceanic energy transport as simulated by atmospheric general circulation models

NASA Technical Reports Server (NTRS)

Gleckler, P. J.; Randall, D. A.; Boer, G.; Colman, R.; Dix, M.; Galin, V.; Helfand, M.; Kiehl, J.; Kitoh, A.; Lau, W.

1995-01-01

This paper summarizes the ocean surface net energy flux simulated by fifteen atmospheric general circulation models constrained by realistically-varying sea surface temperatures and sea ice as part of the Atmospheric Model Intercomparison Project. In general, the simulated energy fluxes are within the very large observational uncertainties. However, the annual mean oceanic meridional heat transport that would be required to balance the simulated surface fluxes is shown to be critically sensitive to the radiative effects of clouds, to the extent that even the sign of the Southern Hemisphere ocean heat transport can be affected by the errors in simulated cloud-radiation interactions. It is suggested that improved treatment of cloud radiative effects should help in the development of coupled atmosphere-ocean general circulation models.

Photovoltaic energy production map of Greece based on simulated and measured data

NASA Astrophysics Data System (ADS)

Vokas, Georgios A.; Lagogiannis, Konstantinos V.; Papageorgas, Panagiotis; Salame, Takla

2017-02-01

The aim of this research is in one hand to reveal the real energy production of a medium scale Photovoltaic (PV) plant located at different sites in Greece and on the other to compare measured data to the predicted ones resulted from one well-known, PV simulation software. During the last ten years a capacity of more than 2,5 GWp of PV systems has been installed in Greece. Almost 37% of the installations are ranged from 10 to 100 kWp due to favorable Feed-in-Tariff policy pricing, according to the Greek regulation. Previous investigations proved a remarkable difference between measured and predicted energy production in Greece regarding all PV systems technologies. For the purposes of this study more than 250 medium scale PV plants have been measured and more than 850 annually energy production data series for those parks have been collected. Those data constitute a great sample that has been compared to more than 225 simulations data resulted by a well-known web software for PV systems energy yield calculations with improved solar radiation database. Additionally, in order to have a visual feeling concerning the real PV energy yield footprint in Greece, an updated map has been developed and illustrated, providing a useful tool for both business and academic purposes.

The analysis of energy consumption of the transport and manipulation process of Fanuc AM100iB robot

NASA Astrophysics Data System (ADS)

Cholewa, A.; Świder, J.; Zbilski, A.

2017-08-01

This article describes test results of energy consumption of Fanuc ArcMate 100iB robot during realization of the transport and manipulation process. The energy consumption test involved the acquisition of values of angular positions of the robot’s encoder shafts and values of tensions and expansions of the electrical currents in three phases of each engine. Based on the simulation results, the analysis of energy consumption was carried out, which specified the tested palletizing process using the set of complete and partial decompositions of the energy consumption of all these factors, which in significant degree impacted the amount of energy taken during the process. Quality of the data provided by the analysis of energy consumption was assessed through validation of results, which involved direct comparison of corresponding parameters, which values were measured and calculated. With regards to the developed analysis of energy consumption, computerized techniques were used to determine the impact of all material factors on the total energy consumption of the machine. The work presents the most significant results of the obtained outcomes.

Overcoming potential energy distortions in constrained internal coordinate molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Kandel, Saugat; Salomon-Ferrer, Romelia; Larsen, Adrien B.; Jain, Abhinandan; Vaidehi, Nagarajan

2016-01-01

The Internal Coordinate Molecular Dynamics (ICMD) method is an attractive molecular dynamics (MD) method for studying the dynamics of bonded systems such as proteins and polymers. It offers a simple venue for coarsening the dynamics model of a system at multiple hierarchical levels. For example, large scale protein dynamics can be studied using torsional dynamics, where large domains or helical structures can be treated as rigid bodies and the loops connecting them as flexible torsions. ICMD with such a dynamic model of the protein, combined with enhanced conformational sampling method such as temperature replica exchange, allows the sampling of large scale domain motion involving high energy barrier transitions. Once these large scale conformational transitions are sampled, all-torsion, or even all-atom, MD simulations can be carried out for the low energy conformations sampled via coarse grained ICMD to calculate the energetics of distinct conformations. Such hierarchical MD simulations can be carried out with standard all-atom forcefields without the need for compromising on the accuracy of the forces. Using constraints to treat bond lengths and bond angles as rigid can, however, distort the potential energy landscape of the system and reduce the number of dihedral transitions as well as conformational sampling. We present here a two-part solution to overcome such distortions of the potential energy landscape with ICMD models. To alleviate the intrinsic distortion that stems from the reduced phase space in torsional MD, we use the Fixman compensating potential. To additionally alleviate the extrinsic distortion that arises from the coupling between the dihedral angles and bond angles within a force field, we propose a hybrid ICMD method that allows the selective relaxing of bond angles. This hybrid ICMD method bridges the gap between all-atom MD and torsional MD. We demonstrate with examples that these methods together offer a solution to eliminate the potential

Overcoming potential energy distortions in constrained internal coordinate molecular dynamics simulations.

PubMed

Kandel, Saugat; Salomon-Ferrer, Romelia; Larsen, Adrien B; Jain, Abhinandan; Vaidehi, Nagarajan

2016-01-28

The Internal Coordinate Molecular Dynamics (ICMD) method is an attractive molecular dynamics (MD) method for studying the dynamics of bonded systems such as proteins and polymers. It offers a simple venue for coarsening the dynamics model of a system at multiple hierarchical levels. For example, large scale protein dynamics can be studied using torsional dynamics, where large domains or helical structures can be treated as rigid bodies and the loops connecting them as flexible torsions. ICMD with such a dynamic model of the protein, combined with enhanced conformational sampling method such as temperature replica exchange, allows the sampling of large scale domain motion involving high energy barrier transitions. Once these large scale conformational transitions are sampled, all-torsion, or even all-atom, MD simulations can be carried out for the low energy conformations sampled via coarse grained ICMD to calculate the energetics of distinct conformations. Such hierarchical MD simulations can be carried out with standard all-atom forcefields without the need for compromising on the accuracy of the forces. Using constraints to treat bond lengths and bond angles as rigid can, however, distort the potential energy landscape of the system and reduce the number of dihedral transitions as well as conformational sampling. We present here a two-part solution to overcome such distortions of the potential energy landscape with ICMD models. To alleviate the intrinsic distortion that stems from the reduced phase space in torsional MD, we use the Fixman compensating potential. To additionally alleviate the extrinsic distortion that arises from the coupling between the dihedral angles and bond angles within a force field, we propose a hybrid ICMD method that allows the selective relaxing of bond angles. This hybrid ICMD method bridges the gap between all-atom MD and torsional MD. We demonstrate with examples that these methods together offer a solution to eliminate the potential