Constraint methods that accelerate free-energy simulations of biomolecules.
Perez, Alberto; MacCallum, Justin L; Coutsias, Evangelos A; Dill, Ken A
2015-12-28
Atomistic molecular dynamics simulations of biomolecules are critical for generating narratives about biological mechanisms. The power of atomistic simulations is that these are physics-based methods that satisfy Boltzmann's law, so they can be used to compute populations, dynamics, and mechanisms. But physical simulations are computationally intensive and do not scale well to the sizes of many important biomolecules. One way to speed up physical simulations is by coarse-graining the potential function. Another way is to harness structural knowledge, often by imposing spring-like restraints. But harnessing external knowledge in physical simulations is problematic because knowledge, data, or hunches have errors, noise, and combinatoric uncertainties. Here, we review recent principled methods for imposing restraints to speed up physics-based molecular simulations that promise to scale to larger biomolecules and motions.
A novel method for energy harvesting simulation based on scenario generation
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 novel energy conversion based method for velocity correction in molecular dynamics simulations
Energy Technology Data Exchange (ETDEWEB)
Jin, Hanhui [School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310027 (China); Collaborative Innovation Center of Advanced Aero-Engine, Hangzhou 310027 (China); Liu, Ningning [School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310027 (China); Ku, Xiaoke, E-mail: xiaokeku@zju.edu.cn [School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310027 (China); Fan, Jianren [State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027 (China)
2017-05-01
Molecular dynamics (MD) simulation has become an important tool for studying micro- or nano-scale dynamics and the statistical properties of fluids and solids. In MD simulations, there are mainly two approaches: equilibrium and non-equilibrium molecular dynamics (EMD and NEMD). In this paper, a new energy conversion based correction (ECBC) method for MD is developed. Unlike the traditional systematic correction based on macroscopic parameters, the ECBC method is developed strictly based on the physical interaction processes between the pair of molecules or atoms. The developed ECBC method can apply to EMD and NEMD directly. While using MD with this method, the difference between the EMD and NEMD is eliminated, and no macroscopic parameters such as external imposed potentials or coefficients are needed. With this method, many limits of using MD are lifted. The application scope of MD is greatly extended.
A novel energy conversion based method for velocity correction in molecular dynamics simulations
International Nuclear Information System (INIS)
Jin, Hanhui; Liu, Ningning; Ku, Xiaoke; Fan, Jianren
2017-01-01
Molecular dynamics (MD) simulation has become an important tool for studying micro- or nano-scale dynamics and the statistical properties of fluids and solids. In MD simulations, there are mainly two approaches: equilibrium and non-equilibrium molecular dynamics (EMD and NEMD). In this paper, a new energy conversion based correction (ECBC) method for MD is developed. Unlike the traditional systematic correction based on macroscopic parameters, the ECBC method is developed strictly based on the physical interaction processes between the pair of molecules or atoms. The developed ECBC method can apply to EMD and NEMD directly. While using MD with this method, the difference between the EMD and NEMD is eliminated, and no macroscopic parameters such as external imposed potentials or coefficients are needed. With this method, many limits of using MD are lifted. The application scope of MD is greatly extended.
Simulation Study of the Energy Performance of Different Space Heating Methods in Plus-energy Housing
DEFF Research Database (Denmark)
Schøtt, Jacob; Andersen, Mads E.; Kazanci, Ongun Berk
2016-01-01
Due to a shortage of energy resources, the focus on indoor environment and energy use in buildings is increasing which sets higher standards for the performance of HVAC systems in buildings. The variety of available heating systems for both residential buildings and office buildings is therefore...... cases the heat source was a natural gas fired condensing boiler, and for the floor heating cases also an air-to-water heat pump was used to compare two heat sources. The systems were also compared in terms of auxiliary energy use for pumps and fans. The results show that the investigated floor heating...... from the low temperature heating potential since an increased floor covering requires higher average water temperatures in the floor loops and decreases the COP of the heat pump. The water-based heating systems required significantly less auxiliary energy input compared to the air-based heating system...
Simulation model of stratified thermal energy storage tank using finite difference method
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
2015-01-01
The reliability of free energy simulations (FES) is limited by two factors: (a) the need for correct sampling and (b) the accuracy of the computational method employed. Classical methods (e.g., force fields) are typically used for FES and present a myriad of challenges, with parametrization being a principle one. On the other hand, parameter-free quantum mechanical (QM) methods tend to be too computationally expensive for adequate sampling. One widely used approach is a combination of methods, where the free energy difference between the two end states is computed by, e.g., molecular mechanics (MM), and the end states are corrected by more accurate methods, such as QM or hybrid QM/MM techniques. Here we report two new approaches that significantly improve the aforementioned scheme; with a focus on how to compute corrections between, e.g., the MM and the more accurate QM calculations. First, a molecular dynamics trajectory that properly samples relevant conformational degrees of freedom is generated. Next, potential energies of each trajectory frame are generated with a QM or QM/MM Hamiltonian. Free energy differences are then calculated based on the QM or QM/MM energies using either a non-Boltzmann Bennett approach (QM-NBB) or non-Boltzmann free energy perturbation (NB-FEP). Both approaches are applied to calculate relative and absolute solvation free energies in explicit and implicit solvent environments. Solvation free energy differences (relative and absolute) between ethane and methanol in explicit solvent are used as the initial test case for QM-NBB. Next, implicit solvent methods are employed in conjunction with both QM-NBB and NB-FEP to compute absolute solvation free energies for 21 compounds. These compounds range from small molecules such as ethane and methanol to fairly large, flexible solutes, such as triacetyl glycerol. Several technical aspects were investigated. Ultimately some best practices are suggested for improving methods that seek to connect
Institute of Scientific and Technical Information of China (English)
2012-01-01
The integrated power generation system of wind, photovoltaic （PV） and energy storage is composed of several wind turbines, PV units and energy storage units. The detailed model of integrated generation is not suitable for the large-scale powe.r system simulation because of the model＇s complexity and long computation time. An equivalent method for power flow calculation and transient simulation of the integrated generation system is proposed based on actual projects, so as to establish the foundation of such integrated system simulation and analysis.
A method for assessing buildings’ energy efficiency by dynamic simulation and experimental activity
International Nuclear Information System (INIS)
Pisello, Anna Laura; Goretti, Michele; Cotana, Franco
2012-01-01
Highlights: ► We propose a new methodology for the evaluation of buildings’ thermal-energetic performance. ► We express year-round performance by an appropriate objective function. ► The procedure allows to translate dynamic simulation results into buildings’ energy guidelines. ► The proposed index shows an important correlation with indoor thermal comfort international index DH. -- Abstract: Buildings’ thermal-energetic assessment and the relative proposal of new technical solutions applied to both summer and winter analyses has a strategic role in increasing the year-round performance of buildings. Buildings’ dynamic analysis is by now a well-established procedure to study effective building energy performance given real climate considerations. Then in this work, a concise and effective methodology for analyzing buildings’ thermal performance in a dynamic environment is proposed and applied to different case studies, consisting of single-family residential buildings’ prototypes. This procedure is aimed to define different performance levels by proper non-dimensional indexes named thermal deviation indexes (TDI). These indexes values could express in a concise way buildings’ thermal behavior, different optimization strategies impact, sensitivity analysis results. Buildings’ prototypes representing the case studies are three free-floating houses where the architectural shape role and the sensitivity of different envelope features are analyzed, also supported by experimental results regarding envelope properties measured on existing residential buildings in Italy. The three prototypes are respectively designed to optimize summer or winter energy performance or to represent the typical Italian house before and after energy efficiency regulation is implemented. To better define the important envelope parameters necessary to calibrate the numerical models, experimental activities are conducted. In particular, thermal insulation level and roof
Gao, Longfei
2018-02-22
We consider numerical simulation of the isotropic elastic wave equations arising from seismic applications with non-trivial land topography. The more flexible finite element method is applied to the shallow region of the simulation domain to account for the topography, and combined with the more efficient finite difference method that is applied to the deep region of the simulation domain. We demonstrate that these two discretization methods, albeit starting from different formulations of the elastic wave equation, can be joined together smoothly via weakly imposed interface conditions. Discrete energy analysis is employed to derive the proper interface treatment, leading to an overall discretization that is energy-conserving. Numerical examples are presented to demonstrate the efficacy of the proposed interface treatment.
Gao, Longfei; Keyes, David E.
2018-01-01
We consider numerical simulation of the isotropic elastic wave equations arising from seismic applications with non-trivial land topography. The more flexible finite element method is applied to the shallow region of the simulation domain to account for the topography, and combined with the more efficient finite difference method that is applied to the deep region of the simulation domain. We demonstrate that these two discretization methods, albeit starting from different formulations of the elastic wave equation, can be joined together smoothly via weakly imposed interface conditions. Discrete energy analysis is employed to derive the proper interface treatment, leading to an overall discretization that is energy-conserving. Numerical examples are presented to demonstrate the efficacy of the proposed interface treatment.
Yaguchi, A; Nagase, K; Ishikawa, M; Iwasaka, T; Odagaki, M; Hosaka, H
2006-01-01
Computer simulation and myocardial cell models were used to evaluate a low-energy defibrillation technique. A generated spiral wave, considered to be a mechanism of fibrillation, and fibrillation were investigated using two myocardial sheet models: a two-dimensional computer simulation model and a two-dimensional experimental model. A new defibrillation technique that has few side effects, which are induced by the current passing into the patient's body, on cardiac muscle is desired. The purpose of the present study is to conduct a basic investigation into an efficient defibrillation method. In order to evaluate the defibrillation method, the propagation of excitation in the myocardial sheet is measured during the normal state and during fibrillation, respectively. The advantages of the low-energy defibrillation technique are then discussed based on the stimulation timing.
Directory of Open Access Journals (Sweden)
E. Bauer
2017-07-01
Full Text Available Glacial cycles of the late Quaternary are controlled by the asymmetrically varying mass balance of continental ice sheets in the Northern Hemisphere. Surface mass balance is governed by processes of ablation and accumulation. Here two ablation schemes, the positive-degree-day (PDD method and the surface energy balance (SEB approach, are compared in transient simulations of the last glacial cycle with the Earth system model of intermediate complexity CLIMBER-2. The standard version of the CLIMBER-2 model incorporates the SEB approach and simulates ice volume variations in reasonable agreement with paleoclimate reconstructions during the entire last glacial cycle. Using results from the standard CLIMBER-2 model version, we simulated ablation with the PDD method in offline mode by applying different combinations of three empirical parameters of the PDD scheme. We found that none of the parameter combinations allow us to simulate a surface mass balance of the American and European ice sheets that is similar to that obtained with the standard SEB method. The use of constant values for the empirical PDD parameters led either to too much ablation during the first phase of the last glacial cycle or too little ablation during the final phase. We then substituted the standard SEB scheme in CLIMBER-2 with the PDD scheme and performed a suite of fully interactive (online simulations of the last glacial cycle with different combinations of PDD parameters. The results of these simulations confirmed the results of the offline simulations: no combination of PDD parameters realistically simulates the evolution of the ice sheets during the entire glacial cycle. The use of constant parameter values in the online simulations leads either to a buildup of too much ice volume at the end of glacial cycle or too little ice volume at the beginning. Even when the model correctly simulates global ice volume at the last glacial maximum (21 ka, it is unable to simulate
Integrated Building Energy Design of a Danish Office Building Based on Monte Carlo Simulation Method
DEFF Research Database (Denmark)
Sørensen, Mathias Juul; Myhre, Sindre Hammer; Hansen, Kasper Kingo
2017-01-01
The focus on reducing buildings energy consumption is gradually increasing, and the optimization of a building’s performance and maximizing its potential leads to great challenges between architects and engineers. In this study, we collaborate with a group of architects on a design project of a new...... office building located in Aarhus, Denmark. Building geometry, floor plans and employee schedules were obtained from the architects which is the basis for this study. This study aims to simplify the iterative design process that is based on the traditional trial and error method in the late design phases...
Jin, Dongliang; Coasne, Benoit
2017-10-24
Different molecular simulation strategies are used to assess the stability of methane hydrate under various temperature and pressure conditions. First, using two water molecular models, free energy calculations consisting of the Einstein molecule approach in combination with semigrand Monte Carlo simulations are used to determine the pressure-temperature phase diagram of methane hydrate. With these calculations, we also estimate the chemical potentials of water and methane and methane occupancy at coexistence. Second, we also consider two other advanced molecular simulation techniques that allow probing the phase diagram of methane hydrate: the direct coexistence method in the Grand Canonical ensemble and the hyperparallel tempering Monte Carlo method. These two direct techniques are found to provide stability conditions that are consistent with the pressure-temperature phase diagram obtained using rigorous free energy calculations. The phase diagram obtained in this work, which is found to be consistent with previous simulation studies, is close to its experimental counterpart provided the TIP4P/Ice model is used to describe the water molecule.
International Nuclear Information System (INIS)
Capeluto, I. Guedi; Ochoa, Carlos E.
2014-01-01
Vast amounts of the European residential stock were built with limited consideration for energy efficiency, yet its refurbishment can help reach national energy reduction goals, decreasing environmental impact. Short-term retrofits with reduced interference to inhabitants can be achieved by upgrading facades with elements that enhance energy efficiency and user comfort. The European Union-funded Meefs Retrofitting (Multifunctional Energy Efficient Façade System) project aims to develop an adaptable mass-produced facade system for energy improvement in existing residential buildings throughout the continent. This article presents a simplified methodology to identify preferred strategies and combinations for the early design stages of such system. This was derived from studying weather characteristics of European regions and outlining climatic energy-saving strategies based on human thermal comfort. Strategies were matched with conceptual technologies like glazing, shading and insulation. The typical building stock was characterized from statistics of previous European projects. Six improvements and combinations were modelled using a simulation model, identifying and ranking preferred configurations. The methodology is summarized in a synoptic scheme identifying the energy rankings of each improvement and combination for the studied climates and façade orientations. - Highlights: • First results of EU project for new energy efficient façade retrofit system. • System consists of prefabricated elements with multiple options for flexibility. • Modular strategies were determined that adapt to different climates. • Technologies matching the strategies were identified. • Presents a method for use and application in different climates across Europe
Water Energy Simulation Toolset
Energy Technology Data Exchange (ETDEWEB)
2017-05-17
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.
Sopori, Bhushan L.
1995-01-01
A method and apparatus for improving the accuracy of the simulation of sunlight reaching the earth's surface includes a relatively small heated chamber having an optical inlet and an optical outlet, the chamber having a cavity that can be filled with a heated stream of CO.sub.2 and water vapor. A simulated beam comprising infrared and near infrared light can be directed through the chamber cavity containing the CO.sub.2 and water vapor, whereby the spectral characteristics of the beam are altered so that the output beam from the chamber contains wavelength bands that accurately replicate atmospheric absorption of solar energy due to atmospheric CO.sub.2 and moisture.
Sopori, B.L.
1995-06-20
A method and apparatus for improving the accuracy of the simulation of sunlight reaching the earth`s surface includes a relatively small heated chamber having an optical inlet and an optical outlet, the chamber having a cavity that can be filled with a heated stream of CO{sub 2} and water vapor. A simulated beam comprising infrared and near infrared light can be directed through the chamber cavity containing the CO{sub 2} and water vapor, whereby the spectral characteristics of the beam are altered so that the output beam from the chamber contains wavelength bands that accurately replicate atmospheric absorption of solar energy due to atmospheric CO{sub 2} and moisture. 8 figs.
International Nuclear Information System (INIS)
Boonekamp, Piet G.M.
2006-01-01
Starting from the conditions for a successful implementation of saving options, a general framework was developed to investigate possible interaction effects in sets of energy policy measures. Interaction regards the influence of one measure on the energy saving effect of another measure. The method delivers a matrix for all combinations of measures, with each cell containing qualitative information on the strength and type of interaction: overlapping, reinforcing, or independent of each other. Results are presented for the set of policy measures on household energy efficiency in the Netherlands for 1990-2003. The second part regards a quantitative analysis of the interaction effects between three major measures: a regulatory energy tax, investment subsidies and regulation of gas use for space heating. Using a detailed bottom-up model, household energy use in the period 1990-2000 was simulated with and without these measures. The results indicate that combinations of two or three policy measures yield 13-30% less effect than the sum of the effects of the separate measures
International Nuclear Information System (INIS)
Turner, Adam C.; Zhang Di; Kim, Hyun J.; DeMarco, John J.; Cagnon, Chris H.; Angel, Erin; Cody, Dianna D.; Stevens, Donna M.; Primak, Andrew N.; McCollough, Cynthia H.; McNitt-Gray, Michael F.
2009-01-01
The purpose of this study was to present a method for generating x-ray source models for performing Monte Carlo (MC) radiation dosimetry simulations of multidetector row CT (MDCT) scanners. These so-called ''equivalent'' source models consist of an energy spectrum and filtration description that are generated based wholly on the measured values and can be used in place of proprietary manufacturer's data for scanner-specific MDCT MC simulations. Required measurements include the half value layers (HVL 1 and HVL 2 ) and the bowtie profile (exposure values across the fan beam) for the MDCT scanner of interest. Using these measured values, a method was described (a) to numerically construct a spectrum with the calculated HVLs approximately equal to those measured (equivalent spectrum) and then (b) to determine a filtration scheme (equivalent filter) that attenuates the equivalent spectrum in a similar fashion as the actual filtration attenuates the actual x-ray beam, as measured by the bowtie profile measurements. Using this method, two types of equivalent source models were generated: One using a spectrum based on both HVL 1 and HVL 2 measurements and its corresponding filtration scheme and the second consisting of a spectrum based only on the measured HVL 1 and its corresponding filtration scheme. Finally, a third type of source model was built based on the spectrum and filtration data provided by the scanner's manufacturer. MC simulations using each of these three source model types were evaluated by comparing the accuracy of multiple CT dose index (CTDI) simulations to measured CTDI values for 64-slice scanners from the four major MDCT manufacturers. Comprehensive evaluations were carried out for each scanner using each kVp and bowtie filter combination available. CTDI experiments were performed for both head (16 cm in diameter) and body (32 cm in diameter) CTDI phantoms using both central and peripheral measurement positions. Both equivalent source model types
Habershon, Scott; Manolopoulos, David E.
2009-12-01
The approximate quantum mechanical ring polymer molecular dynamics (RPMD) and linearized semiclassical initial value representation (LSC-IVR) methods are compared and contrasted in a study of the dynamics of the flexible q-TIP4P/F water model at room temperature. For this water model, a RPMD simulation gives a diffusion coefficient that is only a few percent larger than the classical diffusion coefficient, whereas a LSC-IVR simulation gives a diffusion coefficient that is three times larger. We attribute this discrepancy to the unphysical leakage of initially quantized zero point energy (ZPE) from the intramolecular to the intermolecular modes of the liquid as the LSC-IVR simulation progresses. In spite of this problem, which is avoided by construction in RPMD, the LSC-IVR may still provide a useful approximation to certain short-time dynamical properties which are not so strongly affected by the ZPE leakage. We illustrate this with an application to the liquid water dipole absorption spectrum, for which the RPMD approximation breaks down at frequencies in the O-H stretching region owing to contamination from the internal modes of the ring polymer. The LSC-IVR does not suffer from this difficulty and it appears to provide quite a promising way to calculate condensed phase vibrational spectra.
Habershon, Scott; Manolopoulos, David E
2009-12-28
The approximate quantum mechanical ring polymer molecular dynamics (RPMD) and linearized semiclassical initial value representation (LSC-IVR) methods are compared and contrasted in a study of the dynamics of the flexible q-TIP4P/F water model at room temperature. For this water model, a RPMD simulation gives a diffusion coefficient that is only a few percent larger than the classical diffusion coefficient, whereas a LSC-IVR simulation gives a diffusion coefficient that is three times larger. We attribute this discrepancy to the unphysical leakage of initially quantized zero point energy (ZPE) from the intramolecular to the intermolecular modes of the liquid as the LSC-IVR simulation progresses. In spite of this problem, which is avoided by construction in RPMD, the LSC-IVR may still provide a useful approximation to certain short-time dynamical properties which are not so strongly affected by the ZPE leakage. We illustrate this with an application to the liquid water dipole absorption spectrum, for which the RPMD approximation breaks down at frequencies in the O-H stretching region owing to contamination from the internal modes of the ring polymer. The LSC-IVR does not suffer from this difficulty and it appears to provide quite a promising way to calculate condensed phase vibrational spectra.
DEFF Research Database (Denmark)
Vanhoutteghem, Lies
2013-01-01
with current and future energy requirements, the influence of window size, type and orientation on space heating demand and thermal indoor environment were investigated in EnergyPlus by comparing a window design with an even distribution (same glazingto-floor-area in each room) with a traditional window design....... Charts illustrating a space of solutions for space heating demand defined by targets for daylight and thermal indoor environment were used to discuss the effect of different window parameters and potential conflicts related to window design were identified in deep or narrow southoriented side-lit rooms...
Gamma ray energy loss spectra simulation in NaI detectors with the Monte Carlo method
International Nuclear Information System (INIS)
Vieira, W.J.
1982-01-01
With the aim of studying and applying the Monte Carlo method, a computer code was developed to calculate the pulse height spectra and detector efficiencies for gamma rays incident on NaI (Tl) crystals. The basic detector processes in NaI (Tl) detectors are given together with an outline of Monte Carlo methods and a general review of relevant published works. A detailed description of the application of Monte Carlo methods to ν-ray detection in NaI (Tl) detectors is given. Comparisons are made with published, calculated and experimental, data. (Author) [pt
Computer simulation is a useful tool for benchmarking the electrical and fuel energy consumption and water use in a fluid milk plant. In this study, a computer simulation model of the fluid milk process based on high temperature short time (HTST) pasteurization was extended to include models for pr...
International Nuclear Information System (INIS)
Huang, Jingying; Qin, Datong; Peng, Zhiyuan
2015-01-01
Highlights: • A two-degree-of-freedom lumped thermal model is developed for battery. • The battery thermal model is integrated with vehicle driving model. • Real-time battery thermal responses is obtained. • Active control of current by regenerative braking ratio adjustment is proposed. • More energy is recovered with smaller battery temperature rise. - Abstract: Battery thermal management is important for the safety and reliability of electric vehicle. Based on the parameters obtained from battery hybrid pulse power characterization test, a two-degree-of-freedom lumped thermal model is established. The battery model is then integrated with vehicle driving model to simulate real-time battery thermal responses. An active control method is proposed to reduce heat generation due to regenerative braking. The proposed control method not only subjects to the braking safety regulation, but also adjusts the regenerative braking ratio through a fuzzy controller. By comparing with other regenerative braking scenarios, the effectiveness of the proposed strategy has been validated. According to the results, the proposed control strategy suppresses battery temperature rise by modifying the charge current due to regenerative braking. The overlarge components of current are filtered out whereas the small ones are magnified. Therefore, with smaller battery temperature rise, more energy is recovered. Compared to the traditional passive heat dissipating, the proposed active methodology is feasible and provides a novel solution for electric vehicle battery thermal management.
Sidler, Dominik; Schwaninger, Arthur; Riniker, Sereina
2016-10-21
In molecular dynamics (MD) simulations, free-energy differences are often calculated using free energy perturbation or thermodynamic integration (TI) methods. However, both techniques are only suited to calculate free-energy differences between two end states. Enveloping distribution sampling (EDS) presents an attractive alternative that allows to calculate multiple free-energy differences in a single simulation. In EDS, a reference state is simulated which "envelopes" the end states. The challenge of this methodology is the determination of optimal reference-state parameters to ensure equal sampling of all end states. Currently, the automatic determination of the reference-state parameters for multiple end states is an unsolved issue that limits the application of the methodology. To resolve this, we have generalised the replica-exchange EDS (RE-EDS) approach, introduced by Lee et al. [J. Chem. Theory Comput. 10, 2738 (2014)] for constant-pH MD simulations. By exchanging configurations between replicas with different reference-state parameters, the complexity of the parameter-choice problem can be substantially reduced. A new robust scheme to estimate the reference-state parameters from a short initial RE-EDS simulation with default parameters was developed, which allowed the calculation of 36 free-energy differences between nine small-molecule inhibitors of phenylethanolamine N-methyltransferase from a single simulation. The resulting free-energy differences were in excellent agreement with values obtained previously by TI and two-state EDS simulations.
GEM simulation methods development
International Nuclear Information System (INIS)
Tikhonov, V.; Veenhof, R.
2002-01-01
A review of methods used in the simulation of processes in gas electron multipliers (GEMs) and in the accurate calculation of detector characteristics is presented. Such detector characteristics as effective gas gain, transparency, charge collection and losses have been calculated and optimized for a number of GEM geometries and compared with experiment. A method and a new special program for calculations of detector macro-characteristics such as signal response in a real detector readout structure, and spatial and time resolution of detectors have been developed and used for detector optimization. A detailed development of signal induction on readout electrodes and electronics characteristics are included in the new program. A method for the simulation of charging-up effects in GEM detectors is described. All methods show good agreement with experiment
Energy consumption assessment methods
Energy Technology Data Exchange (ETDEWEB)
Sutherland, K S
1975-01-01
The why, what, and how-to aspects of energy audits for industrial plants, and the application of energy accounting methods to a chemical plant in order to assess energy conservation possibilities are discussed. (LCL)
Wu, Yan; Huang, Yuan-yuan
2018-03-01
Abnormal grain growth of single phase AZ31 Mg alloy in the spatio-temporal process has been simulated by phase field models, and the influencing factors of abnormal grain growth are studied in order to find the ways to control secondary recrystallization in the microstructure. The study aims to find out the mechanisms for abnormal grain growth in real alloys. It is shown from the simulated results that the abnormal grain growth can be controlled by the strain restored energy. Secondary recrystallization after an annealing treatment can be induced if there are grains of a certain orientation in the microstructure with local high restored energy. However, if the value of the local restored energy at a certain grain orientation is not greater than 1.1E 0, there may be no abnormal grain growth in the microstructure.
Reddy, M Rami; Erion, Mark D
2009-12-01
Molecular dynamics (MD) simulations in conjunction with thermodynamic perturbation approach was used to calculate relative solvation free energies of five pairs of small molecules, namely; (1) methanol to ethane, (2) acetone to acetamide, (3) phenol to benzene, (4) 1,1,1 trichloroethane to ethane, and (5) phenylalanine to isoleucine. Two studies were performed to evaluate the dependence of the convergence of these calculations on MD simulation length and starting configuration. In the first study, each transformation started from the same well-equilibrated configuration and the simulation length was varied from 230 to 2,540 ps. The results indicated that for transformations involving small structural changes, a simulation length of 860 ps is sufficient to obtain satisfactory convergence. In contrast, transformations involving relatively large structural changes, such as phenylalanine to isoleucine, require a significantly longer simulation length (>2,540 ps) to obtain satisfactory convergence. In the second study, the transformation was completed starting from three different configurations and using in each case 860 ps of MD simulation. The results from this study suggest that performing one long simulation may be better than averaging results from three different simulations using a shorter simulation length and three different starting configurations.
Methods of channeling simulation
International Nuclear Information System (INIS)
Barrett, J.H.
1989-06-01
Many computer simulation programs have been used to interpret experiments almost since the first channeling measurements were made. Certain aspects of these programs are important in how accurately they simulate ions in crystals; among these are the manner in which the structure of the crystal is incorporated, how any quantity of interest is computed, what ion-atom potential is used, how deflections are computed from the potential, incorporation of thermal vibrations of the lattice atoms, correlations of thermal vibrations, and form of stopping power. Other aspects of the programs are included to improve the speed; among these are table lookup, importance sampling, and the multiparameter method. It is desirable for programs to facilitate incorporation of special features of interest in special situations; examples are relaxations and enhanced vibrations of surface atoms, easy substitution of an alternate potential for comparison, change of row directions from layer to layer in strained-layer lattices, and different vibration amplitudes for substitutional solute or impurity atoms. Ways of implementing all of these aspects and features and the consequences of them will be discussed. 30 refs., 3 figs
Gerber, Paul R.; Mark, Alan E.; van Gunsteren, Wilfred F.
1993-06-01
Derivatives of free energy differences have been calculated by molecular dynamics techniques. The systems under study were ternary complexes of Trimethoprim (TMP) with dihydrofolate reductases of E. coli and chicken liver, containing the cofactor NADPH. Derivatives are taken with respect to modification of TMP, with emphasis on altering the 3-, 4- and 5-substituents of the phenyl ring. A linear approximation allows the encompassing of a whole set of modifications in a single simulation, as opposed to a full perturbation calculation, which requires a separate simulation for each modification. In the case considered here, the proposed technique requires a factor of 1000 less computing effort than a full free energy perturbation calculation. For the linear approximation to yield a significant result, one has to find ways of choosing the perturbation evolution, such that the initial trend mirrors the full calculation. The generation of new atoms requires a careful treatment of the singular terms in the non-bonded interaction. The result can be represented by maps of the changed molecule, which indicate whether complex formation is favoured under movement of partial charges and change in atom polarizabilities. Comparison with experimental measurements of inhibition constants reveals fair agreement in the range of values covered. However, detailed comparison fails to show a significant correlation. Possible reasons for the most pronounced deviations are given.
Energy Technology Data Exchange (ETDEWEB)
Neymark, J.; Judkoff, R.
2002-01-01
This report describes the Building Energy Simulation Test for Heating, Ventilating, and Air-Conditioning Equipment Models (HVAC BESTEST) project conducted by the Tool Evaluation and Improvement International Energy Agency (IEA) Experts Group. The group was composed of experts from the Solar Heating and Cooling (SHC) Programme, Task 22, Subtask A. The current test cases, E100-E200, represent the beginning of work on mechanical equipment test cases; additional cases that would expand the current test suite have been proposed for future development.
Mora Osorio, Camilo Andrés; González Barrios, Andrés Fernando
2016-12-07
Calculation of the Gibbs free energy changes of biological molecules at the oil-water interface is commonly performed with Molecular Dynamics simulations (MD). It is a process that could be performed repeatedly in order to find some molecules of high stability in this medium. Here, an alternative method of calculation has been proposed: a group contribution method (GCM) for peptides based on MD of the twenty classic amino acids to obtain free energy change during the insertion of any peptide chain in water-dodecane interfaces. Multiple MD of the twenty classic amino acids located at the interface of rectangular simulation boxes with a dodecane-water medium were performed. A GCM to calculate the free energy of entire peptides is then proposed. The method uses the summation of the Gibbs free energy of each amino acid adjusted in function of its presence or absence in the chain as well as its hydrophobic characteristics. Validation of the equation was performed with twenty-one peptides all simulated using MD in dodecane-water rectangular boxes in previous work, obtaining an average relative error of 16%.
Stjernschantz, E.M.; Marelius, J.; Medina, C.; Jacobsson, M.; Vermeulen, N.P.E.; Oostenbrink, C.
2006-01-01
An extensive evaluation of the linear interaction energy (LIE) method for the prediction of binding affinity of docked compounds has been performed, with an emphasis on its applicability in lead optimization. An automated setup is presented, which allows for the use of the method in an industrial
Tomasula, P M; Datta, N; Yee, W C F; McAloon, A J; Nutter, D W; Sampedro, F; Bonnaillie, L M
2014-07-01
Computer simulation is a useful tool for benchmarking electrical and fuel energy consumption and water use in a fluid milk plant. In this study, a computer simulation model of the fluid milk process based on high temperature, short time (HTST) pasteurization was extended to include models for processes for shelf-stable milk and extended shelf-life milk that may help prevent the loss or waste of milk that leads to increases in the greenhouse gas (GHG) emissions for fluid milk. The models were for UHT processing, crossflow microfiltration (MF) without HTST pasteurization, crossflow MF followed by HTST pasteurization (MF/HTST), crossflow MF/HTST with partial homogenization, and pulsed electric field (PEF) processing, and were incorporated into the existing model for the fluid milk process. Simulation trials were conducted assuming a production rate for the plants of 113.6 million liters of milk per year to produce only whole milk (3.25%) and 40% cream. Results showed that GHG emissions in the form of process-related CO₂ emissions, defined as CO₂ equivalents (e)/kg of raw milk processed (RMP), and specific energy consumptions (SEC) for electricity and natural gas use for the HTST process alone were 37.6g of CO₂e/kg of RMP, 0.14 MJ/kg of RMP, and 0.13 MJ/kg of RMP, respectively. Emissions of CO2 and SEC for electricity and natural gas use were highest for the PEF process, with values of 99.1g of CO₂e/kg of RMP, 0.44 MJ/kg of RMP, and 0.10 MJ/kg of RMP, respectively, and lowest for the UHT process at 31.4 g of CO₂e/kg of RMP, 0.10 MJ/kg of RMP, and 0.17 MJ/kg of RMP. Estimated unit production costs associated with the various processes were lowest for the HTST process and MF/HTST with partial homogenization at $0.507/L and highest for the UHT process at $0.60/L. The increase in shelf life associated with the UHT and MF processes may eliminate some of the supply chain product and consumer losses and waste of milk and compensate for the small increases in GHG
Seiffert, Betsy R.; Ducrozet, Guillaume
2018-01-01
We examine the implementation of a wave-breaking mechanism into a nonlinear potential flow solver. The success of the mechanism will be studied by implementing it into the numerical model HOS-NWT, which is a computationally efficient, open source code that solves for the free surface in a numerical wave tank using the high-order spectral (HOS) method. Once the breaking mechanism is validated, it can be implemented into other nonlinear potential flow models. To solve for wave-breaking, first a wave-breaking onset parameter is identified, and then a method for computing wave-breaking associated energy loss is determined. Wave-breaking onset is calculated using a breaking criteria introduced by Barthelemy et al. (J Fluid Mech https://arxiv.org/pdf/1508.06002.pdf, submitted) and validated with the experiments of Saket et al. (J Fluid Mech 811:642-658, 2017). Wave-breaking energy dissipation is calculated by adding a viscous diffusion term computed using an eddy viscosity parameter introduced by Tian et al. (Phys Fluids 20(6): 066,604, 2008, Phys Fluids 24(3), 2012), which is estimated based on the pre-breaking wave geometry. A set of two-dimensional experiments is conducted to validate the implemented wave breaking mechanism at a large scale. Breaking waves are generated by using traditional methods of evolution of focused waves and modulational instability, as well as irregular breaking waves with a range of primary frequencies, providing a wide range of breaking conditions to validate the solver. Furthermore, adjustments are made to the method of application and coefficient of the viscous diffusion term with negligible difference, supporting the robustness of the eddy viscosity parameter. The model is able to accurately predict surface elevation and corresponding frequency/amplitude spectrum, as well as energy dissipation when compared with the experimental measurements. This suggests the model is capable of calculating wave-breaking onset and energy dissipation
Uncertainty Quantification in Alchemical Free Energy Methods.
Bhati, Agastya P; Wan, Shunzhou; Hu, Yuan; Sherborne, Brad; Coveney, Peter V
2018-05-02
Alchemical free energy methods have gained much importance recently from several reports of improved ligand-protein binding affinity predictions based on their implementation using molecular dynamics simulations. A large number of variants of such methods implementing different accelerated sampling techniques and free energy estimators are available, each claimed to be better than the others in its own way. However, the key features of reproducibility and quantification of associated uncertainties in such methods have barely been discussed. Here, we apply a systematic protocol for uncertainty quantification to a number of popular alchemical free energy methods, covering both absolute and relative free energy predictions. We show that a reliable measure of error estimation is provided by ensemble simulation-an ensemble of independent MD simulations-which applies irrespective of the free energy method. The need to use ensemble methods is fundamental and holds regardless of the duration of time of the molecular dynamics simulations performed.
Shayesteh, E.
2015-01-01
Electrical energy is one of the most common forms of energy these days. Consequently, electric power system is an indispensable part of any society. However, due to the deregulation of electricity markets and the growth in the share of power generation by uncontrollable renewable energies such as
Czech Academy of Sciences Publication Activity Database
Smith, W.; Lísal, Martin
2002-01-01
Roč. 66, č. 1 (2002), s. 011104-1 - 011104-1 ISSN 1063-651X R&D Projects: GA ČR GA203/02/0805 Grant - others:NSERC(CA) OGP1041 Keywords : MC * simulation * reaction Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.397, year: 2002
Le, Khanh Chau
2012-01-01
The above examples should make clear the necessity of understanding the mechanism of vibrations and waves in order to control them in an optimal way. However vibrations and waves are governed by differential equations which require, as a rule, rather complicated mathematical methods for their analysis. The aim of this textbook is to help students acquire both a good grasp of the first principles from which the governing equations can be derived, and the adequate mathematical methods for their solving. Its distinctive features, as seen from the title, lie in the systematic and intensive use of Hamilton's variational principle and its generalizations for deriving the governing equations of conservative and dissipative mechanical systems, and also in providing the direct variational-asymptotic analysis, whenever available, of the energy and dissipation for the solution of these equations. It will be demonstrated that many well-known methods in dynamics like those of Lindstedt-Poincare, Bogoliubov-Mitropolsky, Ko...
Directory of Open Access Journals (Sweden)
Kyoung-Rok Lee
2013-12-01
Full Text Available A floating Oscillating Water Column (OWC wave energy converter, a Backward Bent Duct Buoy (BBDB, was simulated using a state-of-the-art, two-dimensional, fully-nonlinear Numerical Wave Tank (NWT technique. The hydrodynamic performance of the floating OWC device was evaluated in the time domain. The acceleration potential method, with a full-updated kernel matrix calculation associated with a mode decomposition scheme, was implemented to obtain accurate estimates of the hydrodynamic force and displacement of a freely floating BBDB. The developed NWT was based on the potential theory and the boundary element method with constant panels on the boundaries. The mixed Eulerian-Lagrangian (MEL approach was employed to capture the nonlinear free surfaces inside the chamber that interacted with a pneumatic pressure, induced by the time-varying airflow velocity at the air duct. A special viscous damping was applied to the chamber free surface to represent the viscous energy loss due to the BBDB's shape and motions. The viscous damping coefficient was properly selected using a comparison of the experimental data. The calculated surface elevation, inside and outside the chamber, with a tuned viscous damping correlated reasonably well with the experimental data for various incident wave conditions. The conservation of the total wave energy in the computational domain was confirmed over the entire range of wave frequencies.
Energy Technology Data Exchange (ETDEWEB)
Djuric, Z.; Mihajlov, A.A. (Inst. of Physics, Belgrade (Yugoslavia))
1989-01-01
In the paper we have presented the model method of calculating electrical arc parameters in the macroparticles' electrodynamic accelerator at the given rail width and the given width between them. The method is based on energy losses simulation at the arc's boundary surfaces and is a modification of the one-dimensional version of Powell and Batteh's method. It has been shown that the proposed method is adequate for operative use and that it enables the determination of both macroscopic arc parameters - acceleration, length, electroconductivity, mean temperature and density of particles etc., as well as local arc plasma parameters. The values of these parameters are determined by numerical solutions of the self-consistent system of magnetic-hydrodynamic, material and thermodynamic equations, at the arc's given mass and muzzle voltage between rails. It has also been shown that the proposed method allows the comparison of one-, two- and three-dimensional arc approximations. In the present paper we have used the method assuming that arc plasma is at most doubly ionized and produced exclusively by copper atoms. (orig.).
BLAST: Building energy simulation in Hong Kong
Fong, Sai-Keung
1999-11-01
The characteristics of energy use in buildings under local weather conditions were studied and evaluated using the energy simulation program BLAST-3.0. The parameters used in the energy simulation for the study and evaluation include the architectural features, different internal building heat load settings and weather data. In this study, mathematical equations and the associated coefficients useful to the industry were established. A technology for estimating energy use in buildings under local weather conditions was developed by using the results of this study. A weather data file of Typical Meteorological Years (TMY) has been compiled for building energy studies by analyzing and evaluating the weather of Hong Kong from the year 1979 to 1988. The weather data file TMY and the example weather years 1980 and 1988 were used by BLAST-3.0 to evaluate and study the energy use in different buildings. BLAST-3.0 was compared with other building energy simulation and approximation methods: Bin method and Degree Days method. Energy use in rectangular compartments of different volumes varying from 4,000 m3 to 40,000 m3 with different aspect ratios were analyzed. The use of energy in buildings with concrete roofs was compared with those with glass roofs at indoor temperature 21°C, 23°C and 25°C. Correlation relationships among building energy, space volume, monthly mean temperature and solar radiation were derived and investigated. The effects of space volume, monthly mean temperature and solar radiation on building energy were evaluated. The coefficients of the mathematical relationships between space volume and energy use in a building were computed and found satisfactory. The calculated coefficients can be used for quick estimation of energy use in buildings under similar situations. To study energy use in buildings, the cooling load per floor area against room volume was investigated. The case of an air-conditioned single compartment with 5 m ceiling height was
Simulation approach towards energy flexible manufacturing systems
Beier, Jan
2017-01-01
This authored monograph provides in-depth analysis and methods for aligning electricity demand of manufacturing systems to VRE supply. The book broaches both long-term system changes and real-time manufacturing execution and control, and the author presents a concept with different options for improved energy flexibility including battery, compressed air and embodied energy storage. The reader will also find a detailed application procedure as well as an implementation into a simulation prototype software. The book concludes with two case studies. The target audience primarily comprises research experts in the field of green manufacturing systems. .
New methods in plasma simulation
International Nuclear Information System (INIS)
Mason, R.J.
1990-01-01
The development of implicit methods of particle-in-cell (PIC) computer simulation in recent years, and their merger with older hybrid methods have created a new arsenal of simulation techniques for the treatment of complex practical problems in plasma physics. The new implicit hybrid codes are aimed at transitional problems that lie somewhere between the long time scale, high density regime associated with MHD modeling, and the short time scale, low density regime appropriate to PIC particle-in-cell techniques. This transitional regime arises in ICF coronal plasmas, in pulsed power plasma switches, in Z-pinches, and in foil implosions. Here, we outline how such a merger of implicit and hybrid methods has been carried out, specifically in the ANTHEM computer code, and demonstrate the utility of implicit hybrid simulation in applications. 25 refs., 5 figs
Energy Technology Data Exchange (ETDEWEB)
Neymark J.; Judkoff, R.
2004-12-01
This report documents an additional set of mechanical system test cases that are planned for inclusion in ANSI/ASHRAE STANDARD 140. The cases test a program's modeling capabilities on the working-fluid side of the coil, but in an hourly dynamic context over an expanded range of performance conditions. These cases help to scale the significance of disagreements that are less obvious in the steady-state cases. The report is Vol. 2 of HVAC BESTEST Volume 1. Volume 1 was limited to steady-state test cases that could be solved with analytical solutions. Volume 2 includes hourly dynamic effects, and other cases that cannot be solved analytically. NREL conducted this work in collaboration with the Tool Evaluation and Improvement Experts Group under the International Energy Agency (IEA) Solar Heating and Cooling Programme Task 22.
International Nuclear Information System (INIS)
Capdevielle, Jean-Noel
1972-01-01
This research thesis addresses the study of large air showers and the field of high energy physics and of astrophysics. The author discusses fluctuations undergone by large showers, and reports the development of a simulation method which is used for the determination of the morphology of these large air showers, that is their longitudinal and lateral development. Simulation results are compared with experimental results, and the influence of fluctuations is discussed. The author reports the application of the simulation method to high energy physics and to astrophysics, notably through an example of use of the simulation method in application to the Kiel Group experiment performed at the Pic du Midi. Possible developments are then discussed [fr
Simulation of diesel engine energy conversion processes
Directory of Open Access Journals (Sweden)
А. С. Афанасьев
2016-12-01
Full Text Available In order to keep diesel engines in good working order the troubleshooting methods shall be improved. For their further improvement by parameters of associated processes a need has arisen to develop a diesel engine troubleshooting method based on time parameters of operating cycle. For such method to be developed a computational experiment involving simulation of diesel engine energy conversion processes has been carried out. The simulation was based on the basic mathematical model of reciprocating internal combustion engines, representing a closed system of equations and relationships. The said model has been supplemented with the engine torque dynamics taking into account the current values of in-cylinder processes with different amounts of fuel injected, including zero feed.The torque values obtained by the in-cylinder pressure conversion does not account for mechanical losses, which is why the base simulation program has been supplemented with calculations for the friction and pumping forces. In order to determine the indicator diagram of idle cylinder a transition to zero fuel feed mode and exclusion of the combustion process from calculation have been provisioned.
Scalable Quantum Simulation of Molecular Energies
Directory of Open Access Journals (Sweden)
P. J. J. O’Malley
2016-07-01
Full Text Available We report the first electronic structure calculation performed on a quantum computer without exponentially costly precompilation. We use a programmable array of superconducting qubits to compute the energy surface of molecular hydrogen using two distinct quantum algorithms. First, we experimentally execute the unitary coupled cluster method using the variational quantum eigensolver. Our efficient implementation predicts the correct dissociation energy to within chemical accuracy of the numerically exact result. Second, we experimentally demonstrate the canonical quantum algorithm for chemistry, which consists of Trotterization and quantum phase estimation. We compare the experimental performance of these approaches to show clear evidence that the variational quantum eigensolver is robust to certain errors. This error tolerance inspires hope that variational quantum simulations of classically intractable molecules may be viable in the near future.
Wave Energy Converter Annual Energy Production Uncertainty Using Simulations
Directory of Open Access Journals (Sweden)
Clayton E. Hiles
2016-09-01
Full Text Available Critical to evaluating the economic viability of a wave energy project is: (1 a robust estimate of the electricity production throughout the project lifetime and (2 an understanding of the uncertainty associated with said estimate. Standardization efforts have established mean annual energy production (MAEP as the metric for quantification of wave energy converter (WEC electricity production and the performance matrix approach as the appropriate method for calculation. General acceptance of a method for calculating the MAEP uncertainty has not yet been achieved. Several authors have proposed methods based on the standard engineering approach to error propagation, however, a lack of available WEC deployment data has restricted testing of these methods. In this work the magnitude and sensitivity of MAEP uncertainty is investigated. The analysis is driven by data from simulated deployments of 2 WECs of different operating principle at 4 different locations. A Monte Carlo simulation approach is proposed for calculating the variability of MAEP estimates and is used to explore the sensitivity of the calculation. The uncertainty of MAEP ranged from 2%–20% of the mean value. Of the contributing uncertainties studied, the variability in the wave climate was found responsible for most of the uncertainty in MAEP. Uncertainty in MAEP differs considerably between WEC types and between deployment locations and is sensitive to the length of the input data-sets. This implies that if a certain maximum level of uncertainty in MAEP is targeted, the minimum required lengths of the input data-sets will be different for every WEC-location combination.
Dynamic modeling, simulation and control of energy generation
Vepa, Ranjan
2013-01-01
This book addresses the core issues involved in the dynamic modeling, simulation and control of a selection of energy systems such as gas turbines, wind turbines, fuel cells and batteries. The principles of modeling and control could be applied to other non-convention methods of energy generation such as solar energy and wave energy.A central feature of Dynamic Modeling, Simulation and Control of Energy Generation is that it brings together diverse topics in thermodynamics, fluid mechanics, heat transfer, electro-chemistry, electrical networks and electrical machines and focuses on their appli
Building energy demand aggregation and simulation tools
DEFF Research Database (Denmark)
Gianniou, Panagiota; Heller, Alfred; Rode, Carsten
2015-01-01
to neighbourhoods and cities. Buildings occupy a key place in the development of smart cities as they represent an important potential to integrate smart energy solutions. Building energy consumption affects significantly the performance of the entire energy network. Therefore, a realistic estimation...... of the aggregated building energy use will not only ensure security of supply but also enhance the stabilization of national energy balances. In this study, the aggregation of building energy demand was investigated for a real case in Sønderborg, Denmark. Sixteen single-family houses -mainly built in the 1960s......- were examined, all connected to the regional district heating network. The aggregation of building energy demands was carried out according to typologies, being represented by archetype buildings. These houses were modelled with dynamic energy simulation software and with a simplified simulation tool...
Energy simulation in building design
Hensen, J.L.M.
1992-01-01
Design decision support related to building energy consumption and / or indoor climate, should be based on an integral approach of environment, building, heating, ventilating and airconditioning (HVAC) system and occupants. The tools to achieve this are now available in the form of computer
Dual-energy mammography: simulation studies
International Nuclear Information System (INIS)
Bliznakova, K; Kolitsi, Z; Pallikarakis, N
2006-01-01
This paper presents a mammography simulator and demonstrates its applicability in feasibility studies in dual-energy (DE) subtraction mammography. This mammography simulator is an evolution of a previously presented x-ray imaging simulation system, which has been extended with new functionalities that are specific for DE simulations. The new features include incident exposure and dose calculations, the implementation of a DE subtraction algorithm as well as amendments to the detector and source modelling. The system was then verified by simulating experiments and comparing their results against published data. The simulator was used to carry out a feasibility study of the applicability of DE techniques in mammography, and more precisely to examine whether this modality could result in better visualization and detection of microcalcifications. Investigations were carried out using a 3D breast software phantom of average thickness, monoenergetic and polyenergetic beam spectra and various detector configurations. Dual-shot techniques were simulated. Results showed the advantage of using monoenergetic in comparison with polyenergetic beams. Optimization studies with monochromatic sources were carried out to obtain the optimal low and high incident energies, based on the assessment of the figure of merit of the simulated microcalcifications in the subtracted images. The results of the simulation study with the optimal energies demonstrated that the use of the DE technique can improve visualization and increase detectability, allowing identification of microcalcifications of sizes as small as 200 μm. The quantitative results are also verified by means of a visual inspection of the synthetic images
Numerical simulation methods for electron and ion optics
International Nuclear Information System (INIS)
Munro, Eric
2011-01-01
This paper summarizes currently used techniques for simulation and computer-aided design in electron and ion beam optics. Topics covered include: field computation, methods for computing optical properties (including Paraxial Rays and Aberration Integrals, Differential Algebra and Direct Ray Tracing), simulation of Coulomb interactions, space charge effects in electron and ion sources, tolerancing, wave optical simulations and optimization. Simulation examples are presented for multipole aberration correctors, Wien filter monochromators, imaging energy filters, magnetic prisms, general curved axis systems and electron mirrors.
Simulation of tendon energy storage in pedaling
DEFF Research Database (Denmark)
Rasmussen, John; Damsgaard, Michael; Christensen, Søren Tørholm
2001-01-01
The role of elastic energy stored in tendons during pedaling is investigated by means of numerical simulation using the AnyBody body modeling system. The loss of metabolic energy due to tendon elasticity is computed and compared to the mechanical work involved in the process. The AnyBody simulati...
Kou, Jisheng
2016-02-25
In this paper, we propose an energy-stable evolution method for the calculation of the phase equilibria under given volume, temperature, and moles (VT-flash). An evolution model for describing the dynamics of two-phase fluid system is based on Fick’s law of diffusion for multi-component fluids and the Peng-Robinson equation of state. The mobility is obtained from diffusion coefficients by relating the gradient of chemical potential to the gradient of molar density. The evolution equation for moles of each component is derived using the discretization of diffusion equations, while the volume evolution equation is constructed based on the mechanical mechanism and the Peng-Robinson equation of state. It is proven that the proposed evolution system can well model the VT-flash problem, and moreover, it possesses the property of total energy decay. By using the Euler time scheme to discretize this evolution system, we develop an energy stable algorithm with an adaptive choice strategy of time steps, which allows us to calculate the suitable time step size to guarantee the physical properties of moles and volumes, including positivity, maximum limits, and correct definition of the Helmhotz free energy function. The proposed evolution method is also proven to be energy-stable under the proposed time step choice. Numerical examples are tested to demonstrate efficiency and robustness of the proposed method.
Simulation Tool For Energy Consumption and Production
DEFF Research Database (Denmark)
Nysteen, Michael; Mynderup, Henrik; Poulsen, Bjarne
2013-01-01
In order to promote adoption of smart grid with the general public it is necessary to be able to visualize the benefits of a smart home. Software tools that model the effects can help significantly with this. However, only little work has been done in the area of simulating and visualizing...... the energy consumption in smart homes. This paper presents a prototype simulation tool that allows graphical modeling of a home. Based on the modeled homes the user is able to simulate the energy consumptions and compare scenarios. The simulations are based on dynamic weather and energy price data as well...... as well as appliances and other electrical components used in the modeled homes....
Kou, Jisheng; Sun, Shuyu; Wang, Xiuhua
2016-01-01
In this paper, we propose an energy-stable evolution method for the calculation of the phase equilibria under given volume, temperature, and moles (VT-flash). An evolution model for describing the dynamics of two-phase fluid system is based on Fick
Visualizing Energy on Target: Molecular Dynamics Simulations
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
Energy forecasts, perspectives and methods
Energy Technology Data Exchange (ETDEWEB)
Svensson, J E; Mogren, A
1984-01-01
The authors have analyzed different methods for long term energy prognoses, in particular energy consumption forecasts. Energy supply and price prognoses are also treated, but in a less detailed manner. After defining and discussing the various methods/models used in forecasts, a generalized discussion of the influence on the prognoses from the perspectives (background factors, world view, norms, ideology) of the prognosis makers is given. Some basic formal demands that should be asked from any rational forecast are formulated and discussed. The authors conclude that different forecasting methodologies are supplementing each other. There is no best method, forecasts should be accepted as views of the future from differing perspectives. The primary prognostic problem is to show the possible futures, selecting the wanted future is a question of political process.
QM/MM free energy simulations: recent progress and challenges
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
A Method for Determining Optimal Residential Energy Efficiency Packages
Energy Technology Data Exchange (ETDEWEB)
Polly, B. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Gestwick, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bianchi, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Anderson, R. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Horowitz, S. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Christensen, C. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Judkoff, R. [National Renewable Energy Lab. (NREL), Golden, CO (United States)
2011-04-01
This report describes an analysis method for determining optimal residential energy efficiency retrofit packages and, as an illustrative example, applies the analysis method to a 1960s-era home in eight U.S. cities covering a range of International Energy Conservation Code (IECC) climate regions. The method uses an optimization scheme that considers average energy use (determined from building energy simulations) and equivalent annual cost to recommend optimal retrofit packages specific to the building, occupants, and location.
Computer simulation of high energy displacement cascades
International Nuclear Information System (INIS)
Heinisch, H.L.
1990-01-01
A methodology developed for modeling many aspects of high energy displacement cascades with molecular level computer simulations is reviewed. The initial damage state is modeled in the binary collision approximation (using the MARLOWE computer code), and the subsequent disposition of the defects within a cascade is modeled with a Monte Carlo annealing simulation (the ALSOME code). There are few adjustable parameters, and none are set to physically unreasonable values. The basic configurations of the simulated high energy cascades in copper, i.e., the number, size and shape of damage regions, compare well with observations, as do the measured numbers of residual defects and the fractions of freely migrating defects. The success of these simulations is somewhat remarkable, given the relatively simple models of defects and their interactions that are employed. The reason for this success is that the behavior of the defects is very strongly influenced by their initial spatial distributions, which the binary collision approximation adequately models. The MARLOWE/ALSOME system, with input from molecular dynamics and experiments, provides a framework for investigating the influence of high energy cascades on microstructure evolution. (author)
Fast Learning for Immersive Engagement in Energy Simulations
Energy Technology Data Exchange (ETDEWEB)
Bush, Brian W [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Bugbee, Bruce [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Gruchalla, Kenny M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Krishnan, Venkat K [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Potter, Kristin C [National Renewable Energy Laboratory (NREL), Golden, CO (United States)
2018-04-25
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. Approximation 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.
Simulation of quantum systems by the tomography Monte Carlo method
International Nuclear Information System (INIS)
Bogdanov, Yu I
2007-01-01
A new method of statistical simulation of quantum systems is presented which is based on the generation of data by the Monte Carlo method and their purposeful tomography with the energy minimisation. The numerical solution of the problem is based on the optimisation of the target functional providing a compromise between the maximisation of the statistical likelihood function and the energy minimisation. The method does not involve complicated and ill-posed multidimensional computational procedures and can be used to calculate the wave functions and energies of the ground and excited stationary sates of complex quantum systems. The applications of the method are illustrated. (fifth seminar in memory of d.n. klyshko)
DNA - A Thermal Energy System Simulator
DEFF Research Database (Denmark)
2008-01-01
DNA is a general energy system simulator for both steady-state and dynamic simulation. The program includes a * component model library * thermodynamic state models for fluids and solid fuels and * standard numerical solvers for differential and algebraic equation systems and is free and portable...... (open source, open use, standard FORTRAN77). DNA is text-based using whichever editor, you like best. It has been integerated with the emacs editor. This is usually available on unix-like systems. for windows we recommend the Installation instructions for windows: First install emacs and then run...... the DNA installer...
Methods for Monte Carlo simulations of biomacromolecules.
Vitalis, Andreas; Pappu, Rohit V
2009-01-01
The state-of-the-art for Monte Carlo (MC) simulations of biomacromolecules is reviewed. Available methodologies for sampling conformational equilibria and associations of biomacromolecules in the canonical ensemble, given a continuum description of the solvent environment, are reviewed. Detailed sections are provided dealing with the choice of degrees of freedom, the efficiencies of MC algorithms and algorithmic peculiarities, as well as the optimization of simple movesets. The issue of introducing correlations into elementary MC moves, and the applicability of such methods to simulations of biomacromolecules is discussed. A brief discussion of multicanonical methods and an overview of recent simulation work highlighting the potential of MC methods are also provided. It is argued that MC simulations, while underutilized biomacromolecular simulation community, hold promise for simulations of complex systems and phenomena that span multiple length scales, especially when used in conjunction with implicit solvation models or other coarse graining strategies.
Numerical methods used in simulation
International Nuclear Information System (INIS)
Caseau, Paul; Perrin, Michel; Planchard, Jacques
1978-01-01
The fundamental numerical problem posed by simulation problems is the stability of the resolution diagram. The system of the most used equations is defined, since there is a family of models of increasing complexity with 3, 4 or 5 equations although only models with 3 and 4 equations have been used extensively. After defining what is meant by explicit or implicit, the best established stability results is given for one-dimension problems and then for two-dimension problems. It is shown that two types of discretisation may be defined: four and eight point diagrams (in one or two dimensions) and six and ten point diagrams (in one or two dimensions). To end, some results are given on problems that are not usually treated very much, i.e. non-asymptotic stability and the stability of diagrams based on finite elements [fr
Methods for simulating turbulent phase screen
International Nuclear Information System (INIS)
Zhang Jianzhu; Zhang Feizhou; Wu Yi
2012-01-01
Some methods for simulating turbulent phase screen are summarized, and their characteristics are analyzed by calculating the phase structure function, decomposing phase screens into Zernike polynomials, and simulating laser propagation in the atmosphere. Through analyzing, it is found that, the turbulent high-frequency components are well contained by those phase screens simulated by the FFT method, but the low-frequency components are little contained. The low-frequency components are well contained by screens simulated by Zernike method, but the high-frequency components are not contained enough. The high frequency components contained will be improved by increasing the order of the Zernike polynomial, but they mainly lie in the edge-area. Compared with the two methods above, the fractal method is a better method to simulate turbulent phase screens. According to the radius of the focal spot and the variance of the focal spot jitter, there are limitations in the methods except the fractal method. Combining the FFT and Zernike method or combining the FFT method and self-similar theory to simulate turbulent phase screens is an effective and appropriate way. In general, the fractal method is probably the best way. (authors)
Simulation of Spheromak Evolution and Energy Confinement
International Nuclear Information System (INIS)
Cohen, B; Hooper, E; Cohen, R; Hill, D; McLean, H; Wood, R; Woodruff, S; Sovinec, C; Cone, G
2004-01-01
Simulation results are presented that illustrate the formation and decay of a spheromak plasma driven by a coaxial electrostatic plasma gun, and that model the energy confinement of the plasma. The physics of magnetic reconnection during spheromak formation is also illuminated. The simulations are performed with the three-dimensional, time-dependent, resistive magnetohydrodynamic NIMROD code. The simulation results are compared to data from the SSPX spheromak experiment at the Lawrence Livermore National Laboratory. The simulation results are tracking the experiment with increasing fidelity (e.g., improved agreement with measurements of the magnetic field, fluctuation amplitudes, and electron temperature) as the simulation has been improved in its representations of the geometry of the experiment (plasma gun and flux conserver), the magnetic bias coils, and the detailed time dependence of the current source driving the plasma gun, and uses realistic parameters. The simulations are providing a better understanding of the dominant physics in SSPX, including when the flux surfaces close and the mechanisms limiting the efficiency of electrostatic drive
Simulation of Spheromak Evolution and Energy Confinement
International Nuclear Information System (INIS)
Cohen, B.; Hooper, E.; Cohen, R.; Hill, D.; McLean, H.; Wood, R.; Woodruff, S.
2004-01-01
Simulation results are presented that illustrate the formation and decay of a spheromak plasma driven by a coaxial electrostatic plasma gun, and that model the energy confinement of the plasma. The physics of magnetic reconnection during spheromak formation is also illuminated. The simulations are performed with the three-dimensional, time-dependent, resistive magnetohydrodynamic NIMROD code. The dimensional, simulation results are compared to data from the SSPX spheromak experiment at the Lawrence Livermore National Laboratory. The simulation results are tracking the experiment with increasing fidelity (e.g., improved agreement with measurements of the magnetic field, fluctuation amplitudes, and electron temperature) as the simulation has been improved in its representations of the geometry of the experiment (plasma gun and flux conserver), the magnetic bias coils, and the detailed time dependence of the current source driving the plasma gun, and uses realistic parameters. The simulations are providing a better understanding of the dominant physics in SSPX, including when the flux surfaces close and the mechanisms limiting the efficiency of electrostatic drive
Simulation-based optimization of sustainable national energy systems
International Nuclear Information System (INIS)
Batas Bjelić, Ilija; Rajaković, Nikola
2015-01-01
The goals of the EU2030 energy policy should be achieved cost-effectively by employing the optimal mix of supply and demand side technical measures, including energy efficiency, renewable energy and structural measures. In this paper, the achievement of these goals is modeled by introducing an innovative method of soft-linking of EnergyPLAN with the generic optimization program (GenOpt). This soft-link enables simulation-based optimization, guided with the chosen optimization algorithm, rather than manual adjustments of the decision vectors. In order to obtain EnergyPLAN simulations within the optimization loop of GenOpt, the decision vectors should be chosen and explained in GenOpt for scenarios created in EnergyPLAN. The result of the optimization loop is an optimal national energy master plan (as a case study, energy policy in Serbia was taken), followed with sensitivity analysis of the exogenous assumptions and with focus on the contribution of the smart electricity grid to the achievement of EU2030 goals. It is shown that the increase in the policy-induced total costs of less than 3% is not significant. This general method could be further improved and used worldwide in the optimal planning of sustainable national energy systems. - Highlights: • Innovative method of soft-linking of EnergyPLAN with GenOpt has been introduced. • Optimal national energy master plan has been developed (the case study for Serbia). • Sensitivity analysis on the exogenous world energy and emission price development outlook. • Focus on the contribution of smart energy systems to the EU2030 goals. • Innovative soft-linking methodology could be further improved and used worldwide.
Simulation of the Energy Saver refrigeration system
International Nuclear Information System (INIS)
Barton, H.R. Jr.; Nicholls, J.E.; Mulholland, G.T.
1981-10-01
The helium refrigeration for the Energy Saver is supplied by a Central Helium Liquefier and 24 Satellite Refrigerators installed over a 1-1/4 square mile area. An interactive, software simulator has been developed to calculate the refrigeration available from the cryogenic system over a wide range of operating conditions. The refrigeration system simulator incorporates models of the components which have been developed to quantitatively describe changes in system performance. The simulator output is presented in a real-time display which has been used to search for the optimal operating conditions of the Satellite-Central system, to examine the effect of an extended range of operating parameters and to identify equipment modifications which would improve the system performance
Methodology for Validating Building Energy Analysis Simulations
Energy Technology Data Exchange (ETDEWEB)
Judkoff, R.; Wortman, D.; O' Doherty, B.; Burch, J.
2008-04-01
The objective of this report was to develop a validation methodology for building energy analysis simulations, collect high-quality, unambiguous empirical data for validation, and apply the validation methodology to the DOE-2.1, BLAST-2MRT, BLAST-3.0, DEROB-3, DEROB-4, and SUNCAT 2.4 computer programs. This report covers background information, literature survey, validation methodology, comparative studies, analytical verification, empirical validation, comparative evaluation of codes, and conclusions.
Detector Simulation: Data Treatment and Analysis Methods
Apostolakis, J
2011-01-01
Detector Simulation in 'Data Treatment and Analysis Methods', part of 'Landolt-Börnstein - Group I Elementary Particles, Nuclei and Atoms: Numerical Data and Functional Relationships in Science and Technology, Volume 21B1: Detectors for Particles and Radiation. Part 1: Principles and Methods'. This document is part of Part 1 'Principles and Methods' of Subvolume B 'Detectors for Particles and Radiation' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the Section '4.1 Detector Simulation' of Chapter '4 Data Treatment and Analysis Methods' with the content: 4.1 Detector Simulation 4.1.1 Overview of simulation 4.1.1.1 Uses of detector simulation 4.1.2 Stages and types of simulation 4.1.2.1 Tools for event generation and detector simulation 4.1.2.2 Level of simulation and computation time 4.1.2.3 Radiation effects and background studies 4.1.3 Components of detector simulation 4.1.3.1 Geometry modeling 4.1.3.2 External fields 4.1.3.3 Intro...
Isogeometric methods for numerical simulation
Bordas, Stéphane
2015-01-01
The book presents the state of the art in isogeometric modeling and shows how the method has advantaged. First an introduction to geometric modeling with NURBS and T-splines is given followed by the implementation into computer software. The implementation in both the FEM and BEM is discussed.
A simulation method for lightning surge response of switching power
International Nuclear Information System (INIS)
Wei, Ming; Chen, Xiang
2013-01-01
In order to meet the need of protection design for lighting surge, a prediction method of lightning electromagnetic pulse (LEMP) response which is based on system identification is presented. Experiments of switching power's surge injection were conducted, and the input and output data were sampled, de-noised and de-trended. In addition, the model of energy coupling transfer function was obtained by system identification method. Simulation results show that the system identification method can predict the surge response of linear circuit well. The method proposed in the paper provided a convenient and effective technology for simulation of lightning effect.
Energy-efficient cooking methods
Energy Technology Data Exchange (ETDEWEB)
De, Dilip K. [Department of Physics, University of Jos, P.M.B. 2084, Jos, Plateau State (Nigeria); Muwa Shawhatsu, N. [Department of Physics, Federal University of Technology, Yola, P.M.B. 2076, Yola, Adamawa State (Nigeria); De, N.N. [Department of Mechanical and Aerospace Engineering, The University of Texas at Arlington, Arlington, TX 76019 (United States); Ikechukwu Ajaeroh, M. [Department of Physics, University of Abuja, Abuja (Nigeria)
2013-02-15
Energy-efficient new cooking techniques have been developed in this research. Using a stove with 649{+-}20 W of power, the minimum heat, specific heat of transformation, and on-stove time required to completely cook 1 kg of dry beans (with water and other ingredients) and 1 kg of raw potato are found to be: 710 {+-}kJ, 613 {+-}kJ, and 1,144{+-}10 s, respectively, for beans and 287{+-}12 kJ, 200{+-}9 kJ, and 466{+-}10 s for Irish potato. Extensive researches show that these figures are, to date, the lowest amount of heat ever used to cook beans and potato and less than half the energy used in conventional cooking with a pressure cooker. The efficiency of the stove was estimated to be 52.5{+-}2 %. Discussion is made to further improve the efficiency in cooking with normal stove and solar cooker and to save food nutrients further. Our method of cooking when applied globally is expected to contribute to the clean development management (CDM) potential. The approximate values of the minimum and maximum CDM potentials are estimated to be 7.5 x 10{sup 11} and 2.2 x 10{sup 13} kg of carbon credit annually. The precise estimation CDM potential of our cooking method will be reported later.
Accelerated weight histogram method for exploring free energy landscapes
Energy Technology Data Exchange (ETDEWEB)
Lindahl, V.; Lidmar, J.; Hess, B. [Department of Theoretical Physics and Swedish e-Science Research Center, KTH Royal Institute of Technology, 10691 Stockholm (Sweden)
2014-07-28
Calculating free energies is an important and notoriously difficult task for molecular simulations. The rapid increase in computational power has made it possible to probe increasingly complex systems, yet extracting accurate free energies from these simulations remains a major challenge. Fully exploring the free energy landscape of, say, a biological macromolecule typically requires sampling large conformational changes and slow transitions. Often, the only feasible way to study such a system is to simulate it using an enhanced sampling method. The accelerated weight histogram (AWH) method is a new, efficient extended ensemble sampling technique which adaptively biases the simulation to promote exploration of the free energy landscape. The AWH method uses a probability weight histogram which allows for efficient free energy updates and results in an easy discretization procedure. A major advantage of the method is its general formulation, making it a powerful platform for developing further extensions and analyzing its relation to already existing methods. Here, we demonstrate its efficiency and general applicability by calculating the potential of mean force along a reaction coordinate for both a single dimension and multiple dimensions. We make use of a non-uniform, free energy dependent target distribution in reaction coordinate space so that computational efforts are not wasted on physically irrelevant regions. We present numerical results for molecular dynamics simulations of lithium acetate in solution and chignolin, a 10-residue long peptide that folds into a β-hairpin. We further present practical guidelines for setting up and running an AWH simulation.
A method for ensemble wildland fire simulation
Mark A. Finney; Isaac C. Grenfell; Charles W. McHugh; Robert C. Seli; Diane Trethewey; Richard D. Stratton; Stuart Brittain
2011-01-01
An ensemble simulation system that accounts for uncertainty in long-range weather conditions and two-dimensional wildland fire spread is described. Fuel moisture is expressed based on the energy release component, a US fire danger rating index, and its variation throughout the fire season is modeled using time series analysis of historical weather data. This analysis...
Renewable energy: Method and measures
International Nuclear Information System (INIS)
Nilsen, Trond Hartvedt
2003-01-01
The thesis presents various possibilities for renewable energy in Norway. The wind power would give a practical and economic alternative. The external costs for the wind power would be moderate. In chapter 3 the utility cost analysis for renewable alternatives are studied relative to the macroeconomic efficiency. Some methodical problems and how these analyses are used are reviewed. In the practical utility cost analyses wind power is studied relative to gas power which is the non-renewable alternative present in Norway today. A qualitative part is included. It is not possible to determine whether wind power is preferable to gas power in the macroeconomic perspective. Wind power would be the choice if high environmental and CO2 cleaning costs are expected. The first conclusion to be drawn is that it is difficult to decide whether wind power is the best solution based on cost benefit analysis. However, the alternative seems to be quite robust in the analysis. Due to the central position the energy supplies have in the society this business should be heavily regulated. The sector is also overtaxed as a reduction in consumption is desired. The analysis shows that the system does not function perfectly. The thesis surveys various measures for improving the renewable energy supply and focuses on the wind power. A model for and analysis of the measures are carried out and resulted in a second conclusion. The measures have various properties as to the influence on the market. A subsidy is a fine measure for stimulation production of green power while a tax reduces efficiently the production of black power. A system with green licenses in combination with a subsidy and a tax would be preferable as to increasing the part of renewable energy of the total production. It is therefore necessary to have clearly defined goals and use suitable measures for achieving them. The costs of wind power is falling and it would therefore soon be macroeconomic profitable. It is also
Kinematics and simulation methods to determine the target thickness
International Nuclear Information System (INIS)
Rosales, P.; Aguilar, E.F.; Martinez Q, E.
2001-01-01
Making use of the kinematics and of the particles energy loss two methods for calculating the thickness of a target are described. Through a computer program and other of simulation in which parameters obtained experimentally are used. Several values for a 12 C target thickness were obtained. It is presented a comparison of the obtained values with each one of the used programs. (Author)
Dynamical simulation of heavy ion collisions; VUU and QMD method
International Nuclear Information System (INIS)
Niita, Koji
1992-01-01
We review two simulation methods based on the Vlasov-Uehling-Uhlenbeck (VUU) equation and Quantum Molecular Dynamics (QMD), which are the most widely accepted theoretical framework for the description of intermediate-energy heavy-ion reactions. We show some results of the calculations and compare them with the experimental data. (author)
Simulation of vacancy migration energy in Cu under high strain
International Nuclear Information System (INIS)
Sato, K.; Yoshiie, T.; Satoh, Y.; Xu, Q.; Kiritani, M.
2003-01-01
The activation energy for the migration of vacancies in Cu under high strain was calculated by computer simulation using static methods. The migration energy of vacancies was 0.98 eV in the absence of deformation. It varied with the migration direction and stress direction because the distance between a vacancy and its neighboring atoms changes by deformation. For example, the migration energy for the shortest migration distance was reduced to 9.6 and 39.4% of its initial value by 10% compression and 20% elongation, respectively, while that for the longest migration distance was raised to 171.7 by 20% elongation. If many vacancies are created during high-speed deformation, the lowering of migration energy enables vacancies to escape to sinks such as surfaces, even during the shorter deformation period. The critical strain rate above which the strain rate dependence of vacancy accumulation ceases to exist increases with the lowering of vacancy migration energy
Spectral Methods in Numerical Plasma Simulation
DEFF Research Database (Denmark)
Coutsias, E.A.; Hansen, F.R.; Huld, T.
1989-01-01
An introduction is given to the use of spectral methods in numerical plasma simulation. As examples of the use of spectral methods, solutions to the two-dimensional Euler equations in both a simple, doubly periodic region, and on an annulus will be shown. In the first case, the solution is expanded...
Evaluation of structural reliability using simulation methods
Directory of Open Access Journals (Sweden)
Baballëku Markel
2015-01-01
Full Text Available Eurocode describes the 'index of reliability' as a measure of structural reliability, related to the 'probability of failure'. This paper is focused on the assessment of this index for a reinforced concrete bridge pier. It is rare to explicitly use reliability concepts for design of structures, but the problems of structural engineering are better known through them. Some of the main methods for the estimation of the probability of failure are the exact analytical integration, numerical integration, approximate analytical methods and simulation methods. Monte Carlo Simulation is used in this paper, because it offers a very good tool for the estimation of probability in multivariate functions. Complicated probability and statistics problems are solved through computer aided simulations of a large number of tests. The procedures of structural reliability assessment for the bridge pier and the comparison with the partial factor method of the Eurocodes have been demonstrated in this paper.
Energy models: methods and trends
Energy Technology Data Exchange (ETDEWEB)
Reuter, A [Division of Energy Management and Planning, Verbundplan, Klagenfurt (Austria); Kuehner, R [IER Institute for Energy Economics and the Rational Use of Energy, University of Stuttgart, Stuttgart (Germany); Wohlgemuth, N [Department of Economy, University of Klagenfurt, Klagenfurt (Austria)
1997-12-31
Energy environmental and economical systems do not allow for experimentation since this would be dangerous, too expensive or even impossible. Instead, mathematical models are applied for energy planning. Experimenting is replaced by varying the structure and some parameters of `energy models`, computing the values of depending parameters, comparing variations, and interpreting their outcomings. Energy models are as old as computers. In this article the major new developments in energy modeling will be pointed out. We distinguish between 3 reasons of new developments: progress in computer technology, methodological progress and novel tasks of energy system analysis and planning. 2 figs., 19 refs.
Energy models: methods and trends
International Nuclear Information System (INIS)
Reuter, A.; Kuehner, R.; Wohlgemuth, N.
1996-01-01
Energy environmental and economical systems do not allow for experimentation since this would be dangerous, too expensive or even impossible. Instead, mathematical models are applied for energy planning. Experimenting is replaced by varying the structure and some parameters of 'energy models', computing the values of depending parameters, comparing variations, and interpreting their outcomings. Energy models are as old as computers. In this article the major new developments in energy modeling will be pointed out. We distinguish between 3 reasons of new developments: progress in computer technology, methodological progress and novel tasks of energy system analysis and planning
2-d Simulations of Test Methods
DEFF Research Database (Denmark)
Thrane, Lars Nyholm
2004-01-01
One of the main obstacles for the further development of self-compacting concrete is to relate the fresh concrete properties to the form filling ability. Therefore, simulation of the form filling ability will provide a powerful tool in obtaining this goal. In this paper, a continuum mechanical...... approach is presented by showing initial results from 2-d simulations of the empirical test methods slump flow and L-box. This method assumes a homogeneous material, which is expected to correspond to particle suspensions e.g. concrete, when it remains stable. The simulations have been carried out when...... using both a Newton and Bingham model for characterisation of the rheological properties of the concrete. From the results, it is expected that both the slump flow and L-box can be simulated quite accurately when the model is extended to 3-d and the concrete is characterised according to the Bingham...
Novel Methods for Electromagnetic Simulation and Design
2016-08-03
modeling software that can handle complicated, electrically large objects in a manner that is sufficiently fast to allow design by simulation. 15. SUBJECT...electrically large objects in a manner that is sufficiently fast to allow design by simulation. We also developed new methods for scattering from cavities in a...basis for high fidelity modeling software that can handle complicated, electrically large objects in a manner that is sufficiently fast to allow
Simulation of embedded systems for energy consumption estimation
Energy Technology Data Exchange (ETDEWEB)
Lafond, S.
2009-07-01
Technology developments in semiconductor fabrication along with a rapid expansion of the market for portable devices, such as PDAs and mobile phones, make the energy consumption of embedded systems a major problem. Indeed the need to provide an increasing number of computational intensive applications and at the same time to maximize the battery life of portable devices can be seen as incompatible trends. System simulation is a flexible and convenient method for analyzinging and exploring the performance of a system or sub-system. At the same time, the increasing use of computational intensive applications strengthens the need to maximize the battery life of portable devices. As a consequence, the simulation of embedded systems for energy consumption estimation is becoming essential in order to study and explore the influence of system design choices on the system energy consumption. The original publications presented in the second part of this thesis propose several frameworks for evaluating the effects of particular system and software architectures on the system energy consumption. From a software point of view Java and C based applications are studied, and from a hardware perspective systems using general purpose processor and heterogeneous platforms with dedicated hardware accelerators are analyzed. Papers 1 and 2 present a framework for estimating the energy consumption of an embedded Java Virtual Machine and show how an accurate energy consumption model of Java opcodes can be obtained. Paper 3 evaluates the cost-effectiveness of Forward Error Correction algorithms in terms of energy consumption and demonstrates that a substantial energy saving is achievable in a DVB-H receiver when a FEC algorithm is used for file downloading scenarios. Paper 4 and 5 present the simulation of heterogeneous platforms and point out the drawback of different mechanisms used to synchronize a hardware accelerator used as a peripheral device. Paper 6 shows that the use of a multi
Matrix method for acoustic levitation simulation.
Andrade, Marco A B; Perez, Nicolas; Buiochi, Flavio; Adamowski, Julio C
2011-08-01
A matrix method is presented for simulating acoustic levitators. A typical acoustic levitator consists of an ultrasonic transducer and a reflector. The matrix method is used to determine the potential for acoustic radiation force that acts on a small sphere in the standing wave field produced by the levitator. The method is based on the Rayleigh integral and it takes into account the multiple reflections that occur between the transducer and the reflector. The potential for acoustic radiation force obtained by the matrix method is validated by comparing the matrix method results with those obtained by the finite element method when using an axisymmetric model of a single-axis acoustic levitator. After validation, the method is applied in the simulation of a noncontact manipulation system consisting of two 37.9-kHz Langevin-type transducers and a plane reflector. The manipulation system allows control of the horizontal position of a small levitated sphere from -6 mm to 6 mm, which is done by changing the phase difference between the two transducers. The horizontal position of the sphere predicted by the matrix method agrees with the horizontal positions measured experimentally with a charge-coupled device camera. The main advantage of the matrix method is that it allows simulation of non-symmetric acoustic levitators without requiring much computational effort.
Modeling and Simulation of Energy Recovery from a Photovoltaic ...
African Journals Online (AJOL)
Modeling and Simulation of Energy Recovery from a Photovoltaic Solar cell. ... Photovoltaic (PV) solar cell which converts solar energy directly into electrical energy is one of ... model of the solar panel which could represent the real systems.
Testing simulation and structural models with applications to energy demand
Wolff, Hendrik
2007-12-01
theory. Both results would not necessarily be achieved using standard econometric methods. The final chapter "Daylight Time and Energy" uses a quasi-experiment to evaluate a popular energy conservation policy: we challenge the conventional wisdom that extending Daylight Saving Time (DST) reduces energy demand. Using detailed panel data on half-hourly electricity consumption, prices, and weather conditions from four Australian states we employ a novel 'triple-difference' technique to test the electricity-saving hypothesis. We show that the extension failed to reduce electricity demand and instead increased electricity prices. We also apply the most sophisticated electricity simulation model available in the literature to the Australian data. We find that prior simulation models significantly overstate electricity savings. Our results suggest that extending DST will fail as an instrument to save energy resources.
Renewable energy delivery systems and methods
Walker, Howard Andrew
2013-12-10
A system, method and/or apparatus for the delivery of energy at a site, at least a portion of the energy being delivered by at least one or more of a plurality of renewable energy technologies, the system and method including calculating the load required by the site for the period; calculating the amount of renewable energy for the period, including obtaining a capacity and a percentage of the period for the renewable energy to be delivered; comparing the total load to the renewable energy available; and, implementing one or both of additional and alternative renewable energy sources for delivery of energy to the site.
Model calibration for building energy efficiency simulation
International Nuclear Information System (INIS)
Mustafaraj, Giorgio; Marini, Dashamir; Costa, Andrea; Keane, Marcus
2014-01-01
Highlights: • Developing a 3D model relating to building architecture, occupancy and HVAC operation. • Two calibration stages developed, final model providing accurate results. • Using an onsite weather station for generating the weather data file in EnergyPlus. • Predicting thermal behaviour of underfloor heating, heat pump and natural ventilation. • Monthly energy saving opportunities related to heat pump of 20–27% was identified. - Abstract: This research work deals with an Environmental Research Institute (ERI) building where an underfloor heating system and natural ventilation are the main systems used to maintain comfort condition throughout 80% of the building areas. Firstly, this work involved developing a 3D model relating to building architecture, occupancy and HVAC operation. Secondly, the calibration methodology, which consists of two levels, was then applied in order to insure accuracy and reduce the likelihood of errors. To further improve the accuracy of calibration a historical weather data file related to year 2011, was created from the on-site local weather station of ERI building. After applying the second level of calibration process, the values of Mean bias Error (MBE) and Cumulative Variation of Root Mean Squared Error (CV(RMSE)) on hourly based analysis for heat pump electricity consumption varied within the following ranges: (MBE) hourly from −5.6% to 7.5% and CV(RMSE) hourly from 7.3% to 25.1%. Finally, the building was simulated with EnergyPlus to identify further possibilities of energy savings supplied by a water to water heat pump to underfloor heating system. It found that electricity consumption savings from the heat pump can vary between 20% and 27% on monthly bases
International Nuclear Information System (INIS)
Papageorgiou, George Nathaniel
2005-01-01
In the face of limited energy reserves and the global warming phenomenon, Europe is undergoing a transition from rapidly depleting fossil fuels to renewable unconventional energy sources. During this transition period, energy shortfalls will occur and energy prices will be increasing in an oscillating manner. As a result of the turbulence and dynamicity that will accompany the transition period, energy analysts need new appropriate methods, techniques and tools in order to develop forecasts for the behaviour of energy markets, which would assist in the long term strategic energy planning and policy analysis. This paper reviews energy market behaviour as related to policy formation, and from a dynamic point of view through the use of ''systems thinking'' and ''system dynamics'' principles, provides a framework for modelling the energy production and consumption process in relation to their environment. Thereby, effective energy planning can be developed via computerised simulation using policy experimentation. In a demonstration model depicted in this paper, it is shown that disasters due to attractive policies can be avoided by using simple computer simulation. (Author)
Simulation teaching method in Engineering Optics
Lu, Qieni; Wang, Yi; Li, Hongbin
2017-08-01
We here introduce a pedagogical method of theoretical simulation as one major means of the teaching process of "Engineering Optics" in course quality improvement action plan (Qc) in our school. Students, in groups of three to five, complete simulations of interference, diffraction, electromagnetism and polarization of light; each student is evaluated and scored in light of his performance in the interviews between the teacher and the student, and each student can opt to be interviewed many times until he is satisfied with his score and learning. After three years of Qc practice, the remarkable teaching and learning effect is obatined. Such theoretical simulation experiment is a very valuable teaching method worthwhile for physical optics which is highly theoretical and abstruse. This teaching methodology works well in training students as to how to ask questions and how to solve problems, which can also stimulate their interest in research learning and their initiative to develop their self-confidence and sense of innovation.
Hybrid Method Simulation of Slender Marine Structures
DEFF Research Database (Denmark)
Christiansen, Niels Hørbye
This present thesis consists of an extended summary and five appended papers concerning various aspects of the implementation of a hybrid method which combines classical simulation methods and artificial neural networks. The thesis covers three main topics. Common for all these topics...... only recognize patterns similar to those comprised in the data used to train the network. Fatigue life evaluation of marine structures often considers simulations of more than a hundred different sea states. Hence, in order for this method to be useful, the training data must be arranged so...... that a single neural network can cover all relevant sea states. The applicability and performance of the present hybrid method is demonstrated on a numerical model of a mooring line attached to a floating offshore platform. The second part of the thesis demonstrates how sequential neural networks can be used...
A Simulation Method Measuring Psychomotor Nursing Skills.
McBride, Helena; And Others
1981-01-01
The development of a simulation technique to evaluate performance of psychomotor skills in an undergraduate nursing program is described. This method is used as one admission requirement to an alternate route nursing program. With modifications, any health profession could use this technique where psychomotor skills performance is important.…
Coordinated Optimal Operation Method of the Regional Energy Internet
Directory of Open Access Journals (Sweden)
Rishang Long
2017-05-01
Full Text Available The development of the energy internet has become one of the key ways to solve the energy crisis. This paper studies the system architecture, energy flow characteristics and coordinated optimization method of the regional energy internet. Considering the heat-to-electric ratio of a combined cooling, heating and power unit, energy storage life and real-time electricity price, a double-layer optimal scheduling model is proposed, which includes economic and environmental benefit in the upper layer and energy efficiency in the lower layer. A particle swarm optimizer–individual variation ant colony optimization algorithm is used to solve the computational efficiency and accuracy. Through the calculation and simulation of the simulated system, the energy savings, level of environmental protection and economic optimal dispatching scheme are realized.
International Nuclear Information System (INIS)
Alagoz, B. Baykant; Kaygusuz, Asim; Akcin, Murat; Alagoz, Serkan
2013-01-01
Future smart grids will require a flexible, observable, and controllable network for reliable and efficient energy delivery under uncertain generation and demand conditions. One of the mechanisms for efficient and reliable energy generation is dynamic demand-responsive generation management based on energy price adjustments that creates a balance in energy markets. This study presents a closed-loop PID (proportional–integral–derivative) controller-based price control method for autonomous and real-time balancing of energy demand and generation in smart grid electricity markets. The PID control system can regulate energy prices online to respond dynamically and instantaneously to the varying energy demands of grid consumers. Independent energy suppliers in the smart grid decide whether to sell their energy to the grid according to the energy prices declared by the closed-loop PID controller system. Energy market simulations demonstrate that PID-controlled energy price regulation can effectively maintain an energy balance for hourly demand fluctuations of consumers. - Highlights: • This study presents a control theoretic approach for management of energy balance. • A closed-loop PID controller-based price controlling method is used in smart grid. • The simulation results demonstrate advantages of PID-based energy price control. • This method is appropriate for demand responsive management of smart grid markets
FESetup: Automating Setup for Alchemical Free Energy Simulations.
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.
An Efficient Simulation Method for Rare Events
Rached, Nadhir B.
2015-01-07
Estimating the probability that a sum of random variables (RVs) exceeds a given threshold is a well-known challenging problem. Closed-form expressions for the sum distribution do not generally exist, which has led to an increasing interest in simulation approaches. A crude Monte Carlo (MC) simulation is the standard technique for the estimation of this type of probability. However, this approach is computationally expensive, especially when dealing with rare events. Variance reduction techniques are alternative approaches that can improve the computational efficiency of naive MC simulations. We propose an Importance Sampling (IS) simulation technique based on the well-known hazard rate twisting approach, that presents the advantage of being asymptotically optimal for any arbitrary RVs. The wide scope of applicability of the proposed method is mainly due to our particular way of selecting the twisting parameter. It is worth observing that this interesting feature is rarely satisfied by variance reduction algorithms whose performances were only proven under some restrictive assumptions. It comes along with a good efficiency, illustrated by some selected simulation results comparing the performance of our method with that of an algorithm based on a conditional MC technique.
An Efficient Simulation Method for Rare Events
Rached, Nadhir B.; Benkhelifa, Fatma; Kammoun, Abla; Alouini, Mohamed-Slim; Tempone, Raul
2015-01-01
Estimating the probability that a sum of random variables (RVs) exceeds a given threshold is a well-known challenging problem. Closed-form expressions for the sum distribution do not generally exist, which has led to an increasing interest in simulation approaches. A crude Monte Carlo (MC) simulation is the standard technique for the estimation of this type of probability. However, this approach is computationally expensive, especially when dealing with rare events. Variance reduction techniques are alternative approaches that can improve the computational efficiency of naive MC simulations. We propose an Importance Sampling (IS) simulation technique based on the well-known hazard rate twisting approach, that presents the advantage of being asymptotically optimal for any arbitrary RVs. The wide scope of applicability of the proposed method is mainly due to our particular way of selecting the twisting parameter. It is worth observing that this interesting feature is rarely satisfied by variance reduction algorithms whose performances were only proven under some restrictive assumptions. It comes along with a good efficiency, illustrated by some selected simulation results comparing the performance of our method with that of an algorithm based on a conditional MC technique.
Scenario simulation based assessment of subsurface energy storage
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
Method for Determining Optimal Residential Energy Efficiency Retrofit Packages
Energy Technology Data Exchange (ETDEWEB)
Polly, B.; Gestwick, M.; Bianchi, M.; Anderson, R.; Horowitz, S.; Christensen, C.; Judkoff, R.
2011-04-01
Businesses, government agencies, consumers, policy makers, and utilities currently have limited access to occupant-, building-, and location-specific recommendations for optimal energy retrofit packages, as defined by estimated costs and energy savings. This report describes an analysis method for determining optimal residential energy efficiency retrofit packages and, as an illustrative example, applies the analysis method to a 1960s-era home in eight U.S. cities covering a range of International Energy Conservation Code (IECC) climate regions. The method uses an optimization scheme that considers average energy use (determined from building energy simulations) and equivalent annual cost to recommend optimal retrofit packages specific to the building, occupants, and location. Energy savings and incremental costs are calculated relative to a minimum upgrade reference scenario, which accounts for efficiency upgrades that would occur in the absence of a retrofit because of equipment wear-out and replacement with current minimum standards.
Control Methods Utilizing Energy Optimizing Schemes in Refrigeration Systems
DEFF Research Database (Denmark)
Larsen, L.S; Thybo, C.; Stoustrup, Jakob
2003-01-01
The potential energy savings in refrigeration systems using energy optimal control has been proved to be substantial. This however requires an intelligent control that drives the refrigeration systems towards the energy optimal state. This paper proposes an approach for a control, which drives th...... the condenser pressure towards an optimal state. The objective of this is to present a feasible method that can be used for energy optimizing control. A simulation model of a simple refrigeration system will be used as basis for testing the control method....
Estimating building energy consumption using extreme learning machine method
International Nuclear Information System (INIS)
Naji, Sareh; Keivani, Afram; Shamshirband, Shahaboddin; Alengaram, U. Johnson; Jumaat, Mohd Zamin; Mansor, Zulkefli; Lee, Malrey
2016-01-01
The current energy requirements of buildings comprise a large percentage of the total energy consumed around the world. The demand of energy, as well as the construction materials used in buildings, are becoming increasingly problematic for the earth's sustainable future, and thus have led to alarming concern. The energy efficiency of buildings can be improved, and in order to do so, their operational energy usage should be estimated early in the design phase, so that buildings are as sustainable as possible. An early energy estimate can greatly help architects and engineers create sustainable structures. This study proposes a novel method to estimate building energy consumption based on the ELM (Extreme Learning Machine) method. This method is applied to building material thicknesses and their thermal insulation capability (K-value). For this purpose up to 180 simulations are carried out for different material thicknesses and insulation properties, using the EnergyPlus software application. The estimation and prediction obtained by the ELM model are compared with GP (genetic programming) and ANNs (artificial neural network) models for accuracy. The simulation results indicate that an improvement in predictive accuracy is achievable with the ELM approach in comparison with GP and ANN. - Highlights: • Buildings consume huge amounts of energy for operation. • Envelope materials and insulation influence building energy consumption. • Extreme learning machine is used to estimate energy usage of a sample building. • The key effective factors in this study are insulation thickness and K-value.
Simulation methods for nuclear production scheduling
International Nuclear Information System (INIS)
Miles, W.T.; Markel, L.C.
1975-01-01
Recent developments and applications of simulation methods for use in nuclear production scheduling and fuel management are reviewed. The unique characteristics of the nuclear fuel cycle as they relate to the overall optimization of a mixed nuclear-fossil system in both the short-and mid-range time frame are described. Emphasis is placed on the various formulations and approaches to the mid-range planning problem, whose objective is the determination of an optimal (least cost) system operation strategy over a multi-year planning horizon. The decomposition of the mid-range problem into power system simulation, reactor core simulation and nuclear fuel management optimization, and system integration models is discussed. Present utility practices, requirements, and research trends are described. 37 references
Adaptive implicit method for thermal compositional reservoir simulation
Energy Technology Data Exchange (ETDEWEB)
Agarwal, A.; Tchelepi, H.A. [Society of Petroleum Engineers, Richardson, TX (United States)]|[Stanford Univ., Palo Alto (United States)
2008-10-15
As the global demand for oil increases, thermal enhanced oil recovery techniques are becoming increasingly important. Numerical reservoir simulation of thermal methods such as steam assisted gravity drainage (SAGD) is complex and requires a solution of nonlinear mass and energy conservation equations on a fine reservoir grid. The most currently used technique for solving these equations is the fully IMplicit (FIM) method which is unconditionally stable, allowing for large timesteps in simulation. However, it is computationally expensive. On the other hand, the method known as IMplicit pressure explicit saturations, temperature and compositions (IMPEST) is computationally inexpensive, but it is only conditionally stable and restricts the timestep size. To improve the balance between the timestep size and computational cost, the thermal adaptive IMplicit (TAIM) method uses stability criteria and a switching algorithm, where some simulation variables such as pressure, saturations, temperature, compositions are treated implicitly while others are treated with explicit schemes. This presentation described ongoing research on TAIM with particular reference to thermal displacement processes such as the stability criteria that dictate the maximum allowed timestep size for simulation based on the von Neumann linear stability analysis method; the switching algorithm that adapts labeling of reservoir variables as implicit or explicit as a function of space and time; and, complex physical behaviors such as heat and fluid convection, thermal conduction and compressibility. Key numerical results obtained by enhancing Stanford's General Purpose Research Simulator (GPRS) were also presented along with a list of research challenges. 14 refs., 2 tabs., 11 figs., 1 appendix.
Energy flux simulation in heterogeneous cropland - a two year study
Klein, Christian; Thieme, Christoph; Biernath, Christian; Heinlein, Florian; Priesack, Eckart
2016-04-01
Recent studies show that uncertainties in regional and global climate and weather simulations are partly due to inadequate descriptions of the energy flux exchanges between the land surface and the atmosphere [Stainforth et al. 2005]. One major shortcoming is the limitation of the grid-cell resolution, which is recommended to be about at least 3x3 km² in most models due to limitations in the model physics. To represent each individual grid cell most models select one dominant soil type and one dominant land use type. This resolution, however, is often too coarse in regions where the spatial heterogeneity of soil and land use types are high, e.g. in Central Europe. The relevance of vegetation (e.g. crops), ground cover, and soil properties to the moisture and energy exchanges between the land surface and the atmosphere is well known [McPherson 2007], but the impact of vegetation growth dynamics on energy fluxes is only partly understood [Gayler et al. 2014]. An elegant method to avoid the shortcoming of grid cell resolution is the so called mosaic approach. This approach is part of the recently developed ecosystem model framework Expert-N [Biernath et al. 2013] . The aim of this study was to analyze the impact of the characteristics of five managed field plots, planted with winter wheat, potato and maize on the near surface soil moistures and on the near surface energy flux exchanges of the soil-plant-atmosphere interface. The simulated energy fluxes were compared with eddy flux tower measurements between the respective fields at the research farm Scheyern, North-West of Munich, Germany. To perform these simulations, we coupled the ecosystem model Expert-N to an analytical footprint model [Mauder & Foken 2011] . The coupled model system has the ability to calculate the mixing ratio of the surface energy fluxes at a given point within one grid cell (in this case at the flux tower between the two fields). The approach accounts for the temporarily and spatially
Lagrangian numerical methods for ocean biogeochemical simulations
Paparella, Francesco; Popolizio, Marina
2018-05-01
We propose two closely-related Lagrangian numerical methods for the simulation of physical processes involving advection, reaction and diffusion. The methods are intended to be used in settings where the flow is nearly incompressible and the Péclet numbers are so high that resolving all the scales of motion is unfeasible. This is commonplace in ocean flows. Our methods consist in augmenting the method of characteristics, which is suitable for advection-reaction problems, with couplings among nearby particles, producing fluxes that mimic diffusion, or unresolved small-scale transport. The methods conserve mass, obey the maximum principle, and allow to tune the strength of the diffusive terms down to zero, while avoiding unwanted numerical dissipation effects.
Simulation and the Monte Carlo method
Rubinstein, Reuven Y
2016-01-01
Simulation and the Monte Carlo Method, Third Edition reflects the latest developments in the field and presents a fully updated and comprehensive account of the major topics that have emerged in Monte Carlo simulation since the publication of the classic First Edition over more than a quarter of a century ago. While maintaining its accessible and intuitive approach, this revised edition features a wealth of up-to-date information that facilitates a deeper understanding of problem solving across a wide array of subject areas, such as engineering, statistics, computer science, mathematics, and the physical and life sciences. The book begins with a modernized introduction that addresses the basic concepts of probability, Markov processes, and convex optimization. Subsequent chapters discuss the dramatic changes that have occurred in the field of the Monte Carlo method, with coverage of many modern topics including: Markov Chain Monte Carlo, variance reduction techniques such as the transform likelihood ratio...
Simulating colloid hydrodynamics with lattice Boltzmann methods
International Nuclear Information System (INIS)
Cates, M E; Stratford, K; Adhikari, R; Stansell, P; Desplat, J-C; Pagonabarraga, I; Wagner, A J
2004-01-01
We present a progress report on our work on lattice Boltzmann methods for colloidal suspensions. We focus on the treatment of colloidal particles in binary solvents and on the inclusion of thermal noise. For a benchmark problem of colloids sedimenting and becoming trapped by capillary forces at a horizontal interface between two fluids, we discuss the criteria for parameter selection, and address the inevitable compromise between computational resources and simulation accuracy
An improved method for simulating radiographs
International Nuclear Information System (INIS)
Laguna, G.W.
1986-01-01
The parameters involved in generating actual radiographs and what can and cannot be modeled are examined in this report. Using the spectral distribution of the radiation source and the mass absorption curve for the material comprising the part to be modeled, the actual amount of radiation that would pass through the part and reach the film is determined. This method increases confidence in the results of the simulation and enables the modeling of parts made of multiple materials
An Energy Oriented Model and Simulator for Wireless Sensor etworks
African Journals Online (AJOL)
Nafiisah
Wireless Sensor Network, Energy Modeling, Simulation, Energy. Efficiency ..... xMBCR: This scheme is based on the MBCR strategy, but improves the battery ... Moreover WSNs require large scale deployment (smart dusts) in remote and.
Spectral methods in numerical plasma simulation
International Nuclear Information System (INIS)
Coutsias, E.A.; Hansen, F.R.; Huld, T.; Knorr, G.; Lynov, J.P.
1989-01-01
An introduction is given to the use of spectral methods in numerical plasma simulation. As examples of the use of spectral methods, solutions to the two-dimensional Euler equations in both a simple, doubly periodic region, and on an annulus will be shown. In the first case, the solution is expanded in a two-dimensional Fourier series, while a Chebyshev-Fourier expansion is employed in the second case. A new, efficient algorithm for the solution of Poisson's equation on an annulus is introduced. Problems connected to aliasing and to short wavelength noise generated by gradient steepening are discussed. (orig.)
Electromagnetic simulation using the FDTD method
Sullivan, Dennis M
2013-01-01
A straightforward, easy-to-read introduction to the finite-difference time-domain (FDTD) method Finite-difference time-domain (FDTD) is one of the primary computational electrodynamics modeling techniques available. Since it is a time-domain method, FDTD solutions can cover a wide frequency range with a single simulation run and treat nonlinear material properties in a natural way. Written in a tutorial fashion, starting with the simplest programs and guiding the reader up from one-dimensional to the more complex, three-dimensional programs, this book provides a simple, yet comp
The perceived value of using BIM for energy simulation
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
CALIBRATED ULTRA FAST IMAGE SIMULATIONS FOR THE DARK ENERGY SURVEY
Energy Technology Data Exchange (ETDEWEB)
Bruderer, Claudio; Chang, Chihway; Refregier, Alexandre; Amara, Adam; Bergé, Joel; Gamper, Lukas, E-mail: claudio.bruderer@phys.ethz.ch [Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093 Zürich (Switzerland)
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). We 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.
International Nuclear Information System (INIS)
Antonenko, V.G.; Blau, D.S.
2006-01-01
After all lead tungstate crystals have been fabricated and transferred for assembling of the gamma-spectrometer PHOS in frame of ALICE experiment on the Large Hadron Collider a simulation was performed of the light collection in single scintillation module taking into account realistic properties of entire crystal party [ru
Nuclear methods in environmental and energy research
Energy Technology Data Exchange (ETDEWEB)
Vogt, J. R. [ed.
1977-01-01
The topics considered in the seven sessions were nuclear methods in atmospheric research; nuclear and atomic methodology; nuclear methods in tracer applications; energy exploration, production, and utilization; nuclear methods in environmental monitoring; nuclear methods in water research; and nuclear methods in biological research. Individual abstracts were prepared for each paper. (JSR)
Nuclear methods in environmental and energy research
International Nuclear Information System (INIS)
Vogt, J.R.
1980-01-01
A total of 75 papers were presented on nuclear methods for analysis of environmental and biological samples. Sessions were devoted to software and mathematical methods; nuclear methods in atmospheric and water research; nuclear and atomic methodology; nuclear methods in biology and medicine; and nuclear methods in energy research
Nuclear methods in environmental and energy research
Energy Technology Data Exchange (ETDEWEB)
Vogt, J R [ed.
1980-01-01
A total of 75 papers were presented on nuclear methods for analysis of environmental and biological samples. Sessions were devoted to software and mathematical methods; nuclear methods in atmospheric and water research; nuclear and atomic methodology; nuclear methods in biology and medicine; and nuclear methods in energy research.
Method for producing chemical energy
Jorgensen, Betty S.; Danen, Wayne C.
2004-09-21
Fluoroalkylsilane-coated metal particles having a central metal core, a buffer layer surrounding the core, and a fluoroalkylsilane layer attached to the buffer layer are prepared by combining a chemically reactive fluoroalkylsilane compound with an oxide coated metal particle having a hydroxylated surface. The resulting fluoroalkylsilane layer that coats the particles provides them with excellent resistance to aging. The particles can be blended with oxidant particles to form energetic powder that releases chemical energy when the buffer layer is physically disrupted so that the reductant metal core can react with the oxidant.
Discrete kinetic models from funneled energy landscape simulations.
Directory of Open Access Journals (Sweden)
Nicholas P Schafer
Full Text Available 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.
Econometric methods for energy planning and policy
International Nuclear Information System (INIS)
Bhatia, R.
1989-01-01
The paper reports on the following: econometric models are often used in energy planning and policy for energy demand analysis at the macro and sectorial levels; estimating income and price elasticities of demand which can be used to analyze effects of growth and price changes; assessing interfuel and interfactor substitutions; forecasting energy demand; and estimating cost functions and forecasting supply. The illustrations in the paper are confined to single equation systems estimated by least squares method as used in analyzing changes in aggregate energy demand and sectorial energy demand. The use of econometric methods is illustrated with the help of empirical studies from a few countries (notably India). 2 tabs
Meshless Method for Simulation of Compressible Flow
Nabizadeh Shahrebabak, Ebrahim
In the present age, rapid development in computing technology and high speed supercomputers has made numerical analysis and computational simulation more practical than ever before for large and complex cases. Numerical simulations have also become an essential means for analyzing the engineering problems and the cases that experimental analysis is not practical. There are so many sophisticated and accurate numerical schemes, which do these simulations. The finite difference method (FDM) has been used to solve differential equation systems for decades. Additional numerical methods based on finite volume and finite element techniques are widely used in solving problems with complex geometry. All of these methods are mesh-based techniques. Mesh generation is an essential preprocessing part to discretize the computation domain for these conventional methods. However, when dealing with mesh-based complex geometries these conventional mesh-based techniques can become troublesome, difficult to implement, and prone to inaccuracies. In this study, a more robust, yet simple numerical approach is used to simulate problems in an easier manner for even complex problem. The meshless, or meshfree, method is one such development that is becoming the focus of much research in the recent years. The biggest advantage of meshfree methods is to circumvent mesh generation. Many algorithms have now been developed to help make this method more popular and understandable for everyone. These algorithms have been employed over a wide range of problems in computational analysis with various levels of success. Since there is no connectivity between the nodes in this method, the challenge was considerable. The most fundamental issue is lack of conservation, which can be a source of unpredictable errors in the solution process. This problem is particularly evident in the presence of steep gradient regions and discontinuities, such as shocks that frequently occur in high speed compressible flow
DEFF Research Database (Denmark)
Li, Rongling; Wei, Feng; Zhao, Yang
2017-01-01
Occupant behaviour has a substantial impact on the prediction of building energy performance. To capture this impact, co-simulation is considered an effective approach. It is still a new method in need of more development. In this study, a co-simulation framework is established to couple Energy......Plus with Java via Functional Mock-up Interface (FMI) using the EnergyPlusToFMU software package. This method is applied to a case study of a single occupant office with control of lighting, plug load and thermostat. Two control scenarios are studied. These are occupancy and occupant behaviour based control (OC...
A novel dual energy method for enhanced quantitative computed tomography
Emami, A.; Ghadiri, H.; Rahmim, A.; Ay, M. R.
2018-01-01
Accurate assessment of bone mineral density (BMD) is critically important in clinical practice, and conveniently enabled via quantitative computed tomography (QCT). Meanwhile, dual-energy QCT (DEQCT) enables enhanced detection of small changes in BMD relative to single-energy QCT (SEQCT). In the present study, we aimed to investigate the accuracy of QCT methods, with particular emphasis on a new dual-energy approach, in comparison to single-energy and conventional dual-energy techniques. We used a sinogram-based analytical CT simulator to model the complete chain of CT data acquisitions, and assessed performance of SEQCT and different DEQCT techniques in quantification of BMD. We demonstrate a 120% reduction in error when using a proposed dual-energy Simultaneous Equation by Constrained Least-squares method, enabling more accurate bone mineral measurements.
A new method for simulating human emotions
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
How to make machines express emotions would be instrumental in establishing a completely new paradigm for man ma-chine interaction. A new method for simulating and assessing artificial psychology has been developed for the research of the emo-tion robot. The human psychology activity is regarded as a Markov process. An emotion space and psychology model is constructedbased on Markov process. The conception of emotion entropy is presented to assess the artificial emotion complexity. The simulatingresults play up to human psychology activity. This model can also be applied to consumer-friendly human-computer interfaces, andinteractive video etc.
Simulating condensation on microstructured surfaces using Lattice Boltzmann Method
Alexeev, Alexander; Vasyliv, Yaroslav
2017-11-01
We simulate a single component fluid condensing on 2D structured surfaces with different wettability. To simulate the two phase fluid, we use the athermal Lattice Boltzmann Method (LBM) driven by a pseudopotential force. The pseudopotential force results in a non-ideal equation of state (EOS) which permits liquid-vapor phase change. To account for thermal effects, the athermal LBM is coupled to a finite volume discretization of the temperature evolution equation obtained using a thermal energy rate balance for the specific internal energy. We use the developed model to probe the effect of surface structure and surface wettability on the condensation rate in order to identify microstructure topographies promoting condensation. Financial support is acknowledged from Kimberly-Clark.
Assessment and simulation tools for sustainable energy systems theory and applications
Cavallaro, Fausto
2013-01-01
This book covers both simulations using markal model and linear programming (LP) and methods and applications of multi-criteria, fuzzy-sets, algorithm genetics and neural nets (artificial intelligence) to energy systems.
Nesting Large-Eddy Simulations Within Mesoscale Simulations for Wind Energy Applications
Lundquist, J. K.; Mirocha, J. D.; Chow, F. K.; Kosovic, B.; Lundquist, K. A.
2008-12-01
With increasing demand for more accurate atmospheric simulations for wind turbine micrositing, for operational wind power forecasting, and for more reliable turbine design, simulations of atmospheric flow with resolution of tens of meters or higher are required. These time-dependent large-eddy simulations (LES) account for complex terrain and resolve individual atmospheric eddies on length scales smaller than turbine blades. These small-domain high-resolution simulations are possible with a range of commercial and open- source software, including the Weather Research and Forecasting (WRF) model. In addition to "local" sources of turbulence within an LES domain, changing weather conditions outside the domain can also affect flow, suggesting that a mesoscale model provide boundary conditions to the large-eddy simulations. Nesting a large-eddy simulation within a mesoscale model requires nuanced representations of turbulence. Our group has improved the Weather and Research Forecating model's (WRF) LES capability by implementing the Nonlinear Backscatter and Anisotropy (NBA) subfilter stress model following Kosoviæ (1997) and an explicit filtering and reconstruction technique to compute the Resolvable Subfilter-Scale (RSFS) stresses (following Chow et al, 2005). We have also implemented an immersed boundary method (IBM) in WRF to accommodate complex terrain. These new models improve WRF's LES capabilities over complex terrain and in stable atmospheric conditions. We demonstrate approaches to nesting LES within a mesoscale simulation for farms of wind turbines in hilly regions. Results are sensitive to the nesting method, indicating that care must be taken to provide appropriate boundary conditions, and to allow adequate spin-up of turbulence in the LES domain. This work is performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Comparison of validation methods for forming simulations
Schug, Alexander; Kapphan, Gabriel; Bardl, Georg; Hinterhölzl, Roland; Drechsler, Klaus
2018-05-01
The forming simulation of fibre reinforced thermoplastics could reduce the development time and improve the forming results. But to take advantage of the full potential of the simulations it has to be ensured that the predictions for material behaviour are correct. For that reason, a thorough validation of the material model has to be conducted after characterising the material. Relevant aspects for the validation of the simulation are for example the outer contour, the occurrence of defects and the fibre paths. To measure these features various methods are available. Most relevant and also most difficult to measure are the emerging fibre orientations. For that reason, the focus of this study was on measuring this feature. The aim was to give an overview of the properties of different measuring systems and select the most promising systems for a comparison survey. Selected were an optical, an eddy current and a computer-assisted tomography system with the focus on measuring the fibre orientations. Different formed 3D parts made of unidirectional glass fibre and carbon fibre reinforced thermoplastics were measured. Advantages and disadvantages of the tested systems were revealed. Optical measurement systems are easy to use, but are limited to the surface plies. With an eddy current system also lower plies can be measured, but it is only suitable for carbon fibres. Using a computer-assisted tomography system all plies can be measured, but the system is limited to small parts and challenging to evaluate.
Examples of Applications of Vortex Methods to Wind Energy
DEFF Research Database (Denmark)
Branlard, Emmanuel Simon Pierre
2017-01-01
The current chapter presents wind-energy simulations obtained with the vortex code OmniVor (described in Chap. 44 ) and compared to BEM, CFD and measurements. The chapter begins by comparing rotor loads obtained with vortex methods, BEM and actuator-line simulations of wind turbines under uniform...... and yawed inflows. The second section compares wakes and flow fields obtained by actuator-disk simulations and a free-wake vortex code that uses vortex segments and vortex particles. The third section compares different implementations of viscous diffusion models and investigate their effects...
A simulation of low energy channeling of protons in silicon
International Nuclear Information System (INIS)
Sabin, J.R.
1994-01-01
The authors present early results from the CHANNEL code, which simulates the passage of ionized projectiles through bulk solids. CHANNEL solves the classical equations of motion for the projectile using the force obtained from the gradient of the quantum mechanically derived coulombic potential of the solid (determined via a full potential augmented plane wave FLAPW calculation on the bulk) and a quantum mechanical energy dissipation term, the stopping power, as determined from the local electron density, using the method of Echenique, Nieminen, and Ritchie. The code then generates the trajectory of the ionic projectile for a given initial velocity and a given incident position on the unit cell face. For each incident projectile velocity, the authors generate trajectories for incidence distributed over the channel face. The distribution of ranges generates an implantation profile. In this paper, they report ion (proton) implantation profiles for low energy protons with initial velocity along the (100) and (110) channel directions of diamond structured Silicon
MCB. A continuous energy Monte Carlo burnup simulation code
International Nuclear Information System (INIS)
Cetnar, J.; Wallenius, J.; Gudowski, W.
1999-01-01
A code for integrated simulation of neutrinos and burnup based upon continuous energy Monte Carlo techniques and transmutation trajectory analysis has been developed. Being especially well suited for studies of nuclear waste transmutation systems, the code is an extension of the well validated MCNP transport program of Los Alamos National Laboratory. Among the advantages of the code (named MCB) is a fully integrated data treatment combined with a time-stepping routine that automatically corrects for burnup dependent changes in reaction rates, neutron multiplication, material composition and self-shielding. Fission product yields are treated as continuous functions of incident neutron energy, using a non-equilibrium thermodynamical model of the fission process. In the present paper a brief description of the code and applied methods are given. (author)
Three methods to measure RH bond energies
International Nuclear Information System (INIS)
Berkowitz, J.; Ellison, G.B.; Gutman, D.
1993-01-01
In this paper the authors compare and contrast three powerful methods for experimentally measuring bond energies in polyatomic molecules. The methods are: radical kinetics; gas phase acidity cycles; and photoionization mass spectroscopy. The knowledge of the values of bond energies are a basic piece of information to a chemist. Chemical reactions involve the making and breaking of chemical bonds. It has been shown that comparable bonds in polyatomic molecules, compared to the same bonds in radicals, can be significantly different. These bond energies can be measured in terms of bond dissociation energies
MODELING SIMULATION AND PERFORMANCE STUDY OF GRIDCONNECTED PHOTOVOLTAIC ENERGY SYSTEM
Nagendra K; Karthik J; Keerthi Rao C; Kumar Raja Pemmadi
2017-01-01
This paper presents Modeling Simulation of grid connected Photovoltaic Energy System and performance study using MATLAB/Simulink. The Photovoltaic energy system is considered in three main parts PV Model, Power conditioning System and Grid interface. The Photovoltaic Model is inter-connected with grid through full scale power electronic devices. The simulation is conducted on the PV energy system at normal temperature and at constant load by using MATLAB.
Ductile crack growth simulation from near crack tip dissipated energy
International Nuclear Information System (INIS)
Marie, S.; Chapuliot, S.
2000-01-01
A method to calculate ductile tearing in both small scale fracture mechanics specimens and cracked components is presented. This method is based on an estimation of the dissipated energy calculated near the crack tip. Firstly, the method is presented. It is shown that a characteristic parameter G fr can be obtained, relevant to the dissipated energy in the fracture process. The application of the method to the calculation of side grooved crack tip (CT) specimens of different sizes is examined. The value of G fr is identified by comparing the calculated and experimental load line displacement versus crack extension curve for the smallest CT specimen. With this identified value, it is possible to calculate the global behaviour of the largest specimen. The method is then applied to the calculation of a pipe containing a through-wall thickness crack subjected to a bending moment. This pipe is made of the same material as the CT specimens. It is shown that it is possible to simulate the global behaviour of the structure including the prediction of up to 90-mm crack extension. Local terms such as the equivalent stress or the crack tip opening angle are found to be constant during the crack extension process. This supports the view that G fr controls the fields in the vicinity near the crack tip. (orig.)
Synthetic CT: Simulating low dose single and dual energy protocols from a dual energy scan
International Nuclear Information System (INIS)
Wang, Adam S.; Pelc, Norbert J.
2011-01-01
Purpose: The choice of CT protocol can greatly impact patient dose and image quality. Since acquiring multiple scans at different techniques on a given patient is undesirable, the ability to predict image quality changes starting from a high quality exam can be quite useful. While existing methods allow one to generate simulated images of lower exposure (mAs) from an acquired CT exam, the authors present and validate a new method called synthetic CT that can generate realistic images of a patient at arbitrary low dose protocols (kVp, mAs, and filtration) for both single and dual energy scans. Methods: The synthetic CT algorithm is derived by carefully ensuring that the expected signal and noise are accurate for the simulated protocol. The method relies on the observation that the material decomposition from a dual energy CT scan allows the transmission of an arbitrary spectrum to be predicted. It requires an initial dual energy scan of the patient to either synthesize raw projections of a single energy scan or synthesize the material decompositions of a dual energy scan. The initial dual energy scan contributes inherent noise to the synthesized projections that must be accounted for before adding more noise to simulate low dose protocols. Therefore, synthetic CT is subject to the constraint that the synthesized data have noise greater than the inherent noise. The authors experimentally validated the synthetic CT algorithm across a range of protocols using a dual energy scan of an acrylic phantom with solutions of different iodine concentrations. An initial 80/140 kVp dual energy scan of the phantom provided the material decomposition necessary to synthesize images at 100 kVp and at 120 kVp, across a range of mAs values. They compared these synthesized single energy scans of the phantom to actual scans at the same protocols. Furthermore, material decompositions of a 100/120 kVp dual energy scan are synthesized by adding correlated noise to the initial material
Modeling and Simulation of Smart Energy Systems
DEFF Research Database (Denmark)
Connolly, David; Lund, Henrik; Mathiesen, Brian Vad
2015-01-01
At a global level, it is essential that the world transfers from fossil fuels to renewable energy resources to minimize the implications of climate change, which has been clearly demonstrated by the Intergovernmental Panel on Climate Change (IPCC, 2007a). At a national level, for most countries, ...... are presented on individual technologies and complete energy system strategies, which outline how it is possible to reach a 100% renewable energy system in the coming decades.......At a global level, it is essential that the world transfers from fossil fuels to renewable energy resources to minimize the implications of climate change, which has been clearly demonstrated by the Intergovernmental Panel on Climate Change (IPCC, 2007a). At a national level, for most countries......, the transition to renewable energy will improve energy security of supply, create new jobs, enhance trade, and consequently grow the national economy. However, even with such promising consequences, renewable energy only provided approximately 13% of the world's energy in 2007 (International Energy Agency, 2009a...
Computational Fluid Dynamics and Building Energy Performance Simulation
DEFF Research Database (Denmark)
Nielsen, Peter V.; Tryggvason, Tryggvi
An interconnection between a building energy performance simulation program and a Computational Fluid Dynamics program (CFD) for room air distribution will be introduced for improvement of the predictions of both the energy consumption and the indoor environment. The building energy performance...
Quantum control with NMR methods: Application to quantum simulations
International Nuclear Information System (INIS)
Negrevergne, Camille
2002-01-01
Manipulating information according to quantum laws allows improvements in the efficiency of the way we treat certain problems. Liquid state Nuclear Magnetic Resonance methods allow us to initialize, manipulate and read the quantum state of a system of coupled spins. These methods have been used to realize an experimental small Quantum Information Processor (QIP) able to process information through around hundred elementary operations. One of the main themes of this work was to design, optimize and validate reliable RF-pulse sequences used to 'program' the QIP. Such techniques have been used to run a quantum simulation algorithm for anionic systems. Some experimental results have been obtained on the determination of Eigen energies and correlation function for a toy problem consisting of fermions on a lattice, showing an experimental proof of principle for such quantum simulations. (author) [fr
Cognitive Simulation Driven Domestic Heating Energy Management
Thilakarathne, D.J.; Treur, J.
2016-01-01
Energy management for domestic heating is a non trivial research challenge, especially given the dynamics associated to indoor and outdoor air temperatures, required comfortable temperature set points over time, parameters of the heating source and system, and energy loss rate and capacity of a
Method for optimising the energy of pumps
Skovmose Kallesøe, Carsten; De Persis, Claudio
2011-01-01
The method involves determining whether pumps (pu1, pu5) are directly assigned to loads (v1, v3) as pilot pumps (pu2, pu3) and hydraulically connected upstream of the pilot pumps. The upstream pumps are controlled with variable speed for energy optimization. Energy optimization circuits are selected
Nonstationary signals phase-energy approach-theory and simulations
Klein, R; Braun, S; 10.1006/mssp.2001.1398
2001-01-01
Modern time-frequency methods are intended to deal with a variety of nonstationary signals. One specific class, prevalent in the area of rotating machines, is that of harmonic signals of varying frequencies and amplitude. This paper presents a new adaptive phase-energy (APE) approach for time-frequency representation of varying harmonic signals. It is based on the concept of phase (frequency) paths and the instantaneous power spectral density (PSD). It is this path which represents the dynamic behaviour of the system generating the observed signal. The proposed method utilises dynamic filters based on an extended Nyquist theorem, enabling extraction of signal components with optimal signal-to-noise ratio. The APE detects the most energetic harmonic components (frequency paths) in the analysed signal. Tests on simulated signals show the superiority of the APE in resolution and resolving power as compared to STFT and wavelets wave- packet decomposition. The dynamic filters also enable the reconstruction of the ...
Rare event simulation using Monte Carlo methods
Rubino, Gerardo
2009-01-01
In a probabilistic model, a rare event is an event with a very small probability of occurrence. The forecasting of rare events is a formidable task but is important in many areas. For instance a catastrophic failure in a transport system or in a nuclear power plant, the failure of an information processing system in a bank, or in the communication network of a group of banks, leading to financial losses. Being able to evaluate the probability of rare events is therefore a critical issue. Monte Carlo Methods, the simulation of corresponding models, are used to analyze rare events. This book sets out to present the mathematical tools available for the efficient simulation of rare events. Importance sampling and splitting are presented along with an exposition of how to apply these tools to a variety of fields ranging from performance and dependability evaluation of complex systems, typically in computer science or in telecommunications, to chemical reaction analysis in biology or particle transport in physics. ...
GEANT4 simulations for low energy proton computerized tomography
International Nuclear Information System (INIS)
Milhoretto, Edney; Schelin, Hugo R.; Setti, Joao A.P.; Denyak, Valery; Paschuk, Sergei A.; Evseev, Ivan G.; Assis, Joaquim T. de; Yevseyeva, O.; Lopes, Ricardo T.; Vinagre Filho, Ubirajara M.
2010-01-01
This work presents the recent results of computer simulations for the low energy proton beam tomographic scanner installed at the cyclotron CV-28 of IEN/CNEN. New computer simulations were performed in order to adjust the parameters of previous simulation within the first experimental results and to understand some specific effects that affected the form of the final proton energy spectra. To do this, the energy and angular spread of the initial proton beam were added, and the virtual phantom geometry was specified more accurately in relation to the real one. As a result, a more realistic view on the measurements was achieved.
GEANT4 simulations for low energy proton computerized tomography
Energy Technology Data Exchange (ETDEWEB)
Milhoretto, Edney [Federal University of Technology-Parana, UTFPR, Av. Sete de Setembro 3165, Curitiba-PR (Brazil); Schelin, Hugo R. [Federal University of Technology-Parana, UTFPR, Av. Sete de Setembro 3165, Curitiba-PR (Brazil)], E-mail: schelin@utfpr.edu.br; Setti, Joao A.P.; Denyak, Valery; Paschuk, Sergei A. [Federal University of Technology-Parana, UTFPR, Av. Sete de Setembro 3165, Curitiba-PR (Brazil); Evseev, Ivan G.; Assis, Joaquim T. de; Yevseyeva, O. [Polytechnic Institute/UERJ, Rua Alberto Rangel s/n, N. Friburgo, RJ, Brazil 28630-050 (Brazil); Lopes, Ricardo T. [Nuclear Instr. Lab./COPPE/UFRJ, Av. Horacio Macedo 2030, Rio de Janeiro-RJ (Brazil); Vinagre Filho, Ubirajara M. [Institute of Nuclear Engineering-IEN/CNEN, Rua Helio de Almeida 75, Rio de Janeiro-RJ (Brazil)
2010-04-15
This work presents the recent results of computer simulations for the low energy proton beam tomographic scanner installed at the cyclotron CV-28 of IEN/CNEN. New computer simulations were performed in order to adjust the parameters of previous simulation within the first experimental results and to understand some specific effects that affected the form of the final proton energy spectra. To do this, the energy and angular spread of the initial proton beam were added, and the virtual phantom geometry was specified more accurately in relation to the real one. As a result, a more realistic view on the measurements was achieved.
An Exploration Algorithm for Stochastic Simulators Driven by Energy Gradients
Directory of Open Access Journals (Sweden)
Anastasia S. Georgiou
2017-06-01
Full Text Available In recent work, we have illustrated the construction of an exploration geometry on free energy surfaces: the adaptive computer-assisted discovery of an approximate low-dimensional manifold on which the effective dynamics of the system evolves. Constructing such an exploration geometry involves geometry-biased sampling (through both appropriately-initialized unbiased molecular dynamics and through restraining potentials and, machine learning techniques to organize the intrinsic geometry of the data resulting from the sampling (in particular, diffusion maps, possibly enhanced through the appropriate Mahalanobis-type metric. In this contribution, we detail a method for exploring the conformational space of a stochastic gradient system whose effective free energy surface depends on a smaller number of degrees of freedom than the dimension of the phase space. Our approach comprises two steps. First, we study the local geometry of the free energy landscape using diffusion maps on samples computed through stochastic dynamics. This allows us to automatically identify the relevant coarse variables. Next, we use the information garnered in the previous step to construct a new set of initial conditions for subsequent trajectories. These initial conditions are computed so as to explore the accessible conformational space more efficiently than by continuing the previous, unbiased simulations. We showcase this method on a representative test system.
Computational Simulations and the Scientific Method
Kleb, Bil; Wood, Bill
2005-01-01
As scientific simulation software becomes more complicated, the scientific-software implementor's need for component tests from new model developers becomes more crucial. The community's ability to follow the basic premise of the Scientific Method requires independently repeatable experiments, and model innovators are in the best position to create these test fixtures. Scientific software developers also need to quickly judge the value of the new model, i.e., its cost-to-benefit ratio in terms of gains provided by the new model and implementation risks such as cost, time, and quality. This paper asks two questions. The first is whether other scientific software developers would find published component tests useful, and the second is whether model innovators think publishing test fixtures is a feasible approach.
DEFF Research Database (Denmark)
Christensen, Jørgen Erik; Dalla Rosa, Alessandro; Nagla, Inese
potential of the energy saving in the society it is very important to address the decisive involvement of the end-users. The human behaviour is the factor that affects the most the energy use in low-energy buildings and should be included in energy simulations. The results can then be linked to programs...... the implementation of C02 neutral communities. A link between a dynamic energy simulation program for buildings and a simulation program for district heating networks is demonstrated. The results of the investigation give an example of how to analyze a community and make recommendations for applying the low...... in a cost-effective way in areas with linear heat densities down to 0.20 MWh/(m.year). Even in cases where the user behaviour is not optimal, the system is able to deliver heat to each customer. The low-energy district heating concept could be strategic for reaching ambitious energy and climate targets...
Energy related design decisions deserve simulation approach
Hensen, J.L.M.
1994-01-01
Building energy consumption and indoor climate result from complex dynamic thermal interactions between outdoor environment, building structure, environmental control systems, and occupants. This reality is too complicated to be casted in simple expressions, rules or graphs. After a general overview
Computational Fluid Dynamics and Building Energy Performance Simulation
DEFF Research Database (Denmark)
Nielsen, Peter Vilhelm; Tryggvason, T.
1998-01-01
An interconnection between a building energy performance simulation program and a Computational Fluid Dynamics program (CFD) for room air distribution will be introduced for improvement of the predictions of both the energy consumption and the indoor environment. The building energy performance...... simulation program requires a detailed description of the energy flow in the air movement which can be obtained by a CFD program. The paper describes an energy consumption calculation in a large building, where the building energy simulation program is modified by CFD predictions of the flow between three...... zones connected by open areas with pressure and buoyancy driven air flow. The two programs are interconnected in an iterative procedure. The paper shows also an evaluation of the air quality in the main area of the buildings based on CFD predictions. It is shown that an interconnection between a CFD...
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.
The Simulation of the Recharging Method Based on Solar Radiation for an Implantable Biosensor.
Li, Yun; Song, Yong; Kong, Xianyue; Li, Maoyuan; Zhao, Yufei; Hao, Qun; Gao, Tianxin
2016-09-10
A method of recharging implantable biosensors based on solar radiation is proposed. Firstly, the models of the proposed method are developed. Secondly, the recharging processes based on solar radiation are simulated using Monte Carlo (MC) method and the energy distributions of sunlight within the different layers of human skin have been achieved and discussed. Finally, the simulation results are verified experimentally, which indicates that the proposed method will contribute to achieve a low-cost, convenient and safe method for recharging implantable biosensors.
Methods for Distributed Optimal Energy Management
DEFF Research Database (Denmark)
Brehm, Robert
The presented research deals with the fundamental underlying methods and concepts of how the growing number of distributed generation units based on renewable energy resources and distributed storage devices can be most efficiently integrated into the existing utility grid. In contrast to convent......The presented research deals with the fundamental underlying methods and concepts of how the growing number of distributed generation units based on renewable energy resources and distributed storage devices can be most efficiently integrated into the existing utility grid. In contrast...... to conventional centralised optimal energy flow management systems, here-in, focus is set on how optimal energy management can be achieved in a decentralised distributed architecture such as a multi-agent system. Distributed optimisation methods are introduced, targeting optimisation of energy flow in virtual......-consumption of renewable energy resources in low voltage grids. It can be shown that this method prevents mutual discharging of batteries and prevents peak loads, a supervisory control instance can dictate the level of autarchy from the utility grid. Further it is shown that the problem of optimal energy flow management...
Attia, S.G.; Gratia, E.; De Herde, A.; Hensen, J.L.M.
2013-01-01
Building performance simulation (BPS) is the basis for informed decision-making of Net Zero Energy Buildings (NZEBs) design. This paper aims to investigate the use of building performance simulation tools as a method of informing the design decision of NZEBs. The aim of this study is to evaluate the
Directory of Open Access Journals (Sweden)
Kaushikbhai C. Parmar
2017-04-01
Full Text Available Simulation gives different results when using different methods for the same simulation. Autodesk Moldflow Simulation software provide two different facilities for creating mold for the simulation of injection molding process. Mold can be created inside the Moldflow or it can be imported as CAD file. The aim of this paper is to study the difference in the simulation results like mold temperature part temperature deflection in different direction time for the simulation and coolant temperature for this two different methods.
Energy Dependent Streaming in Lattice Boltzmann Simulations
Czech Academy of Sciences Publication Activity Database
Pavlo, Pavol; Vahala, G.; Vahala, L.
2001-01-01
Roč. 46, č. 8 (2001), s. 241 ISSN 0003-0503. [Annual Meeting of the Division of Plasma Physics of the American Physical Society/43rd./. Long Beach, CA, 29.10.2001-02.11.2001] R&D Projects: GA ČR GA202/00/1216 Institutional research plan: CEZ:AV0Z2043910 Keywords : Lattice Boltzmann Simulations Subject RIV: BL - Plasma and Gas Discharge Physics
Methods for risk estimation in nuclear energy
Energy Technology Data Exchange (ETDEWEB)
Gauvenet, A [CEA, 75 - Paris (France)
1979-01-01
The author presents methods for estimating the different risks related to nuclear energy: immediate or delayed risks, individual or collective risks, risks of accidents and long-term risks. These methods have attained a highly valid level of elaboration and their application to other industrial or human problems is currently under way, especially in English-speaking countries.
Energy deposition profile on ISOLDE Beam Dumps by FLUKA simulations
Vlachoudis, V
2014-01-01
In this report an estimation of the energy deposited on the current ISOLDE beam dumps obtained by means of FLUKA simulation code is presented. This is done for both ones GPS and HRS. Some estimations of temperature raise are given based on the assumption of adiabatic increase from energy deposited by the impinging protons. However, the results obtained here in relation to temperature are only a rough estimate. They are meant to be further studied through thermomechanical simulations using the energyprofiles hereby obtained.
CFD simulation of energy sources in EAF
Directory of Open Access Journals (Sweden)
Ekrem Büyükkaya
2017-10-01
Full Text Available Modeling of energy production and heat transfer by carbon combustion and electrical arc is performed using Fluent computational fluid dynamic (CFD software in this manuscript. The heat energy generated by carbon burning and electric arc radiation during combustion of the scrap in the EAO has been examined in detail. For this reason, modeling studies have utilized the combustion reactions of carbon particles and electromagnetically emitted radiation. Firstly, particle surface and gas reactions are investigated in terms of injected carbon burning. The result of the chemical reaction at the burner outlet is about 3000 K of the core temperature during combustion. It has been determined that the temperature which acts on the slag is 2200 K. The radiation temperature was found to be highest in the area under the electrodes and fell to 1850 K in the area where the melt was poured. Under steady operating conditions, it was seen that electric energy was absorbed by about 5.5% of the electrodes. As a result of this study, CFD software can be used to model combustion and radiation and energy generation and heat transfer for an electric arc furnace at the design study.
Simulation of the human energy system / Cornelis Petrus Botha
Botha, Cornelis Petrus
2002-01-01
Preface - Biotechnology is generally accepted to be the next economical wave of the future. In order to attain the many benefits associated with this growing industry simulation modelling techniques have to be implemented successfully. One of the simulations that ne' ed to be performed is that of the human energy system. Pharmaceutical companies are currently pouring vast amounts of capital into research regarding simulation of bodily processes. Their aim is to develop cure...
DEFF Research Database (Denmark)
Dalla Rosa, Alessandro
2012-01-01
The future will demand implementation of C02 neutral communities, the consequences being a far more complex design of the whole energy system, since the future energy infrastructures will be dynamic and climate responsive systems. Software able to work with such level of complexity is at present...... a missing link in the development. In this paper is demonstrated how a link between a dynamic Building Simulation Programme (BSP) and a simulation program for District Heating (DH) networks can give important information during the design phase. By using a BSP it is possible to analyze the influence...... of the human behaviour regarding the building and link the results to the simulation program for DH networks. The results show that human behaviour can lead to 50% higher heating demand and 60% higher peak loads than expected according to reference values in standardized calculation of energy demand...
Simulation of pulsed accidental energy release in a reactor core
International Nuclear Information System (INIS)
Ryshanskii, V.A.; Ivanov, A.G.; Uskov, A.A.
1995-01-01
At the present time the strength of the load-bearing members of VVER and fast reactors during a hypothetical accident is ordinarily investigated in model experiments [1]. A power burst during an accident is simulated by a nonnuclear exothermal reaction in water, which simulates the coolant and fills the model. The problem is to make the correct choice of the simulator of the accidental energy burst as an effective (i.e., sufficiently high working capacity) source of dangerous loads, corresponding to the conditions of an accident. What factors and parameters determine the energy release? The answers to these questions are contradictory
Energy conservation in molecular dynamics simulations of classical systems
DEFF Research Database (Denmark)
Toxværd, Søren; Heilmann, Ole; Dyre, J. C.
2012-01-01
Classical Newtonian dynamics is analytic and the energy of an isolated system is conserved. The energy of such a system, obtained by the discrete “Verlet” algorithm commonly used in molecular dynamics simulations, fluctuates but is conserved in the mean. This is explained by the existence...
Evaluation of null-point detection methods on simulation data
Olshevsky, Vyacheslav; Fu, Huishan; Vaivads, Andris; Khotyaintsev, Yuri; Lapenta, Giovanni; Markidis, Stefano
2014-05-01
We model the measurements of artificial spacecraft that resemble the configuration of CLUSTER propagating in the particle-in-cell simulation of turbulent magnetic reconnection. The simulation domain contains multiple isolated X-type null-points, but the majority are O-type null-points. Simulations show that current pinches surrounded by twisted fields, analogous to laboratory pinches, are formed along the sequences of O-type nulls. In the simulation, the magnetic reconnection is mainly driven by the kinking of the pinches, at spatial scales of several ion inertial lentghs. We compute the locations of magnetic null-points and detect their type. When the satellites are separated by the fractions of ion inertial length, as it is for CLUSTER, they are able to locate both the isolated null-points, and the pinches. We apply the method to the real CLUSTER data and speculate how common are pinches in the magnetosphere, and whether they play a dominant role in the dissipation of magnetic energy.
A survey of modelling methods for high-fidelity wind farm simulations using large eddy simulation
DEFF Research Database (Denmark)
Breton, Simon-Philippe; Sumner, J.; Sørensen, Jens Nørkær
2017-01-01
surveys the most common schemes available to model the rotor, atmospheric conditions and terrain effects within current state-of-the-art LES codes, of which an overview is provided. A summary of the experimental research data available for validation of LES codes within the context of single and multiple......Large eddy simulations (LES) of wind farms have the capability to provide valuable and detailed information about the dynamics of wind turbine wakes. For this reason, their use within the wind energy research community is on the rise, spurring the development of new models and methods. This review...
A fast mollified impulse method for biomolecular atomistic simulations
Energy Technology Data Exchange (ETDEWEB)
Fath, L., E-mail: lukas.fath@kit.edu [Institute for App. and Num. Mathematics, Karlsruhe Institute of Technology (Germany); Hochbruck, M., E-mail: marlis.hochbruck@kit.edu [Institute for App. and Num. Mathematics, Karlsruhe Institute of Technology (Germany); Singh, C.V., E-mail: chandraveer.singh@utoronto.ca [Department of Materials Science & Engineering, University of Toronto (Canada)
2017-03-15
Classical integration methods for molecular dynamics are inherently limited due to resonance phenomena occurring at certain time-step sizes. The mollified impulse method can partially avoid this problem by using appropriate filters based on averaging or projection techniques. However, existing filters are computationally expensive and tedious in implementation since they require either analytical Hessians or they need to solve nonlinear systems from constraints. In this work we follow a different approach based on corotation for the construction of a new filter for (flexible) biomolecular simulations. The main advantages of the proposed filter are its excellent stability properties and ease of implementation in standard softwares without Hessians or solving constraint systems. By simulating multiple realistic examples such as peptide, protein, ice equilibrium and ice–ice friction, the new filter is shown to speed up the computations of long-range interactions by approximately 20%. The proposed filtered integrators allow step sizes as large as 10 fs while keeping the energy drift less than 1% on a 50 ps simulation.
Particle identification methods in High Energy Physics
Energy Technology Data Exchange (ETDEWEB)
Va' Vra, J.
2000-01-27
This paper deals with two major particle identification methods: dE/dx and Cherenkov detection. In the first method, the authors systematically compare existing dE/dx data with various predictions available in the literature, such as the Particle Data group recommendation, and judge the overall consistency. To my knowledge, such comparison was not done yet in a published form for the gaseous detectors used in High-Energy physics. As far as the second method, there are two major Cherenkov light detection techniques: the threshold and the Ring imaging methods. The authors discuss the recent trend in these techniques.
Correcting for the free energy costs of bond or angle constraints in molecular dynamics simulations.
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
Energy saving baking methods. Energibesparende bagemetoder
Energy Technology Data Exchange (ETDEWEB)
Gry, P.
1988-01-01
The project ''Energy Saving Baking Methods'', run as part of the Energy Research Project-1984, and has as its aim to investigate potentials for energy saving by employing microwaves in the baking process. The project is a follow-up of the Nordic Industry Fund project which was completed in 1983. Smaller test ovens with IR long waves, warm air convection and microwaves of 2,47 GHz were used. Measurements of heat distribution from all three energy sources have been made. Extensive experiments have been carried out in order to develope baking methods for white loaves which are energy saving, but where the quality of the bread does not undergo any form of deterioration. Tests were made using microwaves alone, and in combination with hot air and IR. A resulting saving 35% baking time was achieved, and a further reduction of baking time can be reached where a greater improvement of energy distribution can take place, especially in the case of microwaves and IR. (AB).
Excitation methods for energy dispersive analysis
International Nuclear Information System (INIS)
Jaklevic, J.M.
1976-01-01
The rapid development in recent years of energy dispersive x-ray fluorescence analysis has been based primarily on improvements in semiconductor detector x-ray spectrometers. However, the whole analysis system performance is critically dependent on the availability of optimum methods of excitation for the characteristic x rays in specimens. A number of analysis facilities based on various methods of excitation have been developed over the past few years. A discussion is given of the features of various excitation methods including charged particles, monochromatic photons, and broad-energy band photons. The effects of the excitation method on background and sensitivity are discussed from both theoretical and experimental viewpoints. Recent developments such as pulsed excitation and polarized photons are also discussed
Numerical methods in simulation of resistance welding
DEFF Research Database (Denmark)
Nielsen, Chris Valentin; Martins, Paulo A.F.; Zhang, Wenqi
2015-01-01
Finite element simulation of resistance welding requires coupling betweenmechanical, thermal and electrical models. This paper presents the numerical models and theircouplings that are utilized in the computer program SORPAS. A mechanical model based onthe irreducible flow formulation is utilized...... a resistance welding point of view, the most essential coupling between the above mentioned models is the heat generation by electrical current due to Joule heating. The interaction between multiple objects is anothercritical feature of the numerical simulation of resistance welding because it influences...... thecontact area and the distribution of contact pressure. The numerical simulation of resistancewelding is illustrated by a spot welding example that includes subsequent tensile shear testing...
Virtual Crowds Methods, Simulation, and Control
Pelechano, Nuria; Allbeck, Jan
2008-01-01
There are many applications of computer animation and simulation where it is necessary to model virtual crowds of autonomous agents. Some of these applications include site planning, education, entertainment, training, and human factors analysis for building evacuation. Other applications include simulations of scenarios where masses of people gather, flow, and disperse, such as transportation centers, sporting events, and concerts. Most crowd simulations include only basic locomotive behaviors possibly coupled with a few stochastic actions. Our goal in this survey is to establish a baseline o
Systems and methods for wave energy conversion
MacDonald, Daniel G.; Cantara, Justin; Nathan, Craig; Lopes, Amy M.; Green, Brandon E.
2017-02-28
Systems for wave energy conversion that have components that can survive the harsh marine environment and that can be attached to fixed structures, such as a pier, and having the ability to naturally adjust for tidal height and methods for their use are presented.
Radiation energy calibrating system and method
International Nuclear Information System (INIS)
Jacobson, A.F.
1980-01-01
A radiation energy calibrating system and method which uses a pair of calibrated detectors for measurements of radiation intensity from x-ray tubes for a non-invasive determination of the electrical characteristics; I.E., the tube potential and/or current
Energy requirements during sponge cake baking: Experimental and simulated approach
International Nuclear Information System (INIS)
Ureta, M. Micaela; Goñi, Sandro M.; Salvadori, Viviana O.; Olivera, Daniela F.
2017-01-01
Highlights: • Sponge cake energy consumption during baking was studied. • High oven temperature and forced convection mode favours oven energy savings. • Forced convection produced higher weight loss thus a higher product energy demand. • Product energy demand was satisfactorily estimated by the baking model applied. • The greatest energy efficiency corresponded to the forced convection mode. - Abstract: Baking is a high energy demanding process, which requires special attention in order to know and improve its efficiency. In this work, energy consumption associated to sponge cake baking is investigated. A wide range of operative conditions (two ovens, three convection modes, three oven temperatures) were compared. Experimental oven energy consumption was estimated taking into account the heating resistances power and a usage factor. Product energy demand was estimated from both experimental and modeling approaches considering sensible and latent heat. Oven energy consumption results showed that high oven temperature and forced convection mode favours energy savings. Regarding product energy demand, forced convection produced faster and higher weight loss inducing a higher energy demand. Besides, this parameter was satisfactorily estimated by the baking model applied, with an average error between experimental and simulated values in a range of 8.0–10.1%. Finally, the energy efficiency results indicated that it increased linearly with the effective oven temperature and that the greatest efficiency corresponded to the forced convection mode.
Hybrid Building Performance Simulation Models for Industrial Energy Efficiency Applications
Directory of Open Access Journals (Sweden)
Peter Smolek
2018-06-01
Full Text Available In the challenge of achieving environmental sustainability, industrial production plants, as large contributors to the overall energy demand of a country, are prime candidates for applying energy efficiency measures. A modelling approach using cubes is used to decompose a production facility into manageable modules. All aspects of the facility are considered, classified into the building, energy system, production and logistics. This approach leads to specific challenges for building performance simulations since all parts of the facility are highly interconnected. To meet this challenge, models for the building, thermal zones, energy converters and energy grids are presented and the interfaces to the production and logistics equipment are illustrated. The advantages and limitations of the chosen approach are discussed. In an example implementation, the feasibility of the approach and models is shown. Different scenarios are simulated to highlight the models and the results are compared.
Simulation and energy analysis of distributed electric heating system
Yu, Bo; Han, Shenchao; Yang, Yanchun; Liu, Mingyuan
2018-02-01
Distributed electric heating system assistssolar heating systemby using air-source heat pump. Air-source heat pump as auxiliary heat sourcecan make up the defects of the conventional solar thermal system can provide a 24 - hour high - efficiency work. It has certain practical value and practical significance to reduce emissions and promote building energy efficiency. Using Polysun software the system is simulated and compared with ordinary electric boiler heating system. The simulation results show that upon energy request, 5844.5kW energy is saved and 3135kg carbon - dioxide emissions are reduced and5844.5 kWhfuel and energy consumption is decreased with distributed electric heating system. Theeffect of conserving energy and reducing emissions using distributed electric heating systemis very obvious.
Solar energy utilization by physical methods.
Wolf, M
1974-04-19
On the basis of the estimated contributions of these differing methods of the utilization of solar energy, their total energy delivery impact on the projected U.S. energy economy (9) can be evaluated (Fig. 5). Despite this late energy impact, the actual sales of solar energy utilization equipment will be significant at an early date. Potential sales in photovoltaic arrays alone could exceed $400 million by 1980, in order to meet the projected capacity buildup (10). Ultimately, the total energy utilization equipment industry should attain an annual sales volume of several tens of billion dollars in the United States, comparable to that of several other energy related industries. Varying amounts of technology development are required to assure the technical and economic feasibility of the different solar energy utilization methods. Several of these developments are far enough along that the paths can be analyzed from the present time to the time of demonstration of technical and economic feasibility, and from there to production and marketing readiness. After that point, a period of market introduction will follow, which will differ in duration according to the type of market addressed. It may be noted that the present rush to find relief from the current energy problem, or to be an early leader in entering a new market, can entail shortcuts in sound engineering practice, particularly in the areas of design for durability and easy maintenance, or of proper application engineering. The result can be loss of customer acceptance, as has been experienced in the past with various products, including solar water heaters. Since this could cause considerable delay in achieving the expected total energy impact, it will be important to spend adequate time at this stage for thorough development. Two other aspects are worth mentioning. The first is concerned with the economic impacts. Upon reflection on this point, one will observe that largescale solar energy utilization will
EVALUATION OF ENERGY PERFORMANCE USING DOE-2 ENERGY SIMULATION PROGRAM IN SINGAPORE
Directory of Open Access Journals (Sweden)
Po Seng Kian
2000-01-01
Full Text Available Recently, due to worldwide energy cost rising significantly, there has been an essential need to minimize the energy consumption. This global warning address many countries including Singapore realizing the important of energy efficiency in industries and buildings. This paper deals with analyzing the energy consumption of an 11-storey commercial building in Singapore using DOE-2 Energy Simulation Program. A study is made on the benefits derived from modifying the building envelope, space system setting, air-conditioning plant, and lighting. This encompasses a description of its quantitative impact on cooling load, energy consumption and energy saving achieved as compared with the original building. Following this, a life cycle costing is done to determine the economic benefits attained from this modification. This study shows that some alternative solutions can be achieved using energy simulation program to conserve the energy consumption.
Kinetic Energy from Supernova Feedback in High-resolution Galaxy Simulations
Simpson, Christine M.; Bryan, Greg L.; Hummels, Cameron; Ostriker, Jeremiah P.
2015-08-01
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 109 M⊙ dwarf halo. We find that in high-density media (≳50 cm-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.
Free energy simulations with the AMOEBA polarizable force field and metadynamics on GPU platform.
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.
Simulation-based Investigations of Electrostatic Beam Energy Analysers
Pahl, Hannes
2015-01-01
An energy analyser is needed to measure the beam energy profile behind the REX-EBIS at ISOLDE. The device should be able to operate with an accuracy of 1 V at voltages up to 30 kV. In order to find a working concept for an electrostatic energy analyser different designs were evaluated with simulations. A spherical device and its design issues are presented. The potential deformation effects of grids at high voltages and their influence on the energy resolution were investigated. First tests were made with a grid-free ring electrode device and show promising results.
Rocklin, Gabriel J; Mobley, David L; Dill, Ken A; Hünenberger, Philippe H
2013-11-14
The calculation of a protein-ligand binding free energy based on molecular dynamics (MD) simulations generally relies on a thermodynamic cycle in which the ligand is alchemically inserted into the system, both in the solvated protein and free in solution. The corresponding ligand-insertion free energies are typically calculated in nanoscale computational boxes simulated under periodic boundary conditions and considering electrostatic interactions defined by a periodic lattice-sum. This is distinct from the ideal bulk situation of a system of macroscopic size simulated under non-periodic boundary conditions with Coulombic electrostatic interactions. This discrepancy results in finite-size effects, which affect primarily the charging component of the insertion free energy, are dependent on the box size, and can be large when the ligand bears a net charge, especially if the protein is charged as well. This article investigates finite-size effects on calculated charging free energies using as a test case the binding of the ligand 2-amino-5-methylthiazole (net charge +1 e) to a mutant form of yeast cytochrome c peroxidase in water. Considering different charge isoforms of the protein (net charges -5, 0, +3, or +9 e), either in the absence or the presence of neutralizing counter-ions, and sizes of the cubic computational box (edges ranging from 7.42 to 11.02 nm), the potentially large magnitude of finite-size effects on the raw charging free energies (up to 17.1 kJ mol(-1)) is demonstrated. Two correction schemes are then proposed to eliminate these effects, a numerical and an analytical one. Both schemes are based on a continuum-electrostatics analysis and require performing Poisson-Boltzmann (PB) calculations on the protein-ligand system. While the numerical scheme requires PB calculations under both non-periodic and periodic boundary conditions, the latter at the box size considered in the MD simulations, the analytical scheme only requires three non-periodic PB
Energy Technology Data Exchange (ETDEWEB)
Rocklin, Gabriel J. [Department of Pharmaceutical Chemistry, University of California San Francisco, 1700 4th St., San Francisco, California 94143-2550, USA and Biophysics Graduate Program, University of California San Francisco, 1700 4th St., San Francisco, California 94143-2550 (United States); Mobley, David L. [Departments of Pharmaceutical Sciences and Chemistry, University of California Irvine, 147 Bison Modular, Building 515, Irvine, California 92697-0001, USA and Department of Chemistry, University of New Orleans, 2000 Lakeshore Drive, New Orleans, Louisiana 70148 (United States); Dill, Ken A. [Laufer Center for Physical and Quantitative Biology, 5252 Stony Brook University, Stony Brook, New York 11794-0001 (United States); Hünenberger, Philippe H., E-mail: phil@igc.phys.chem.ethz.ch [Laboratory of Physical Chemistry, Swiss Federal Institute of Technology, ETH, 8093 Zürich (Switzerland)
2013-11-14
The calculation of a protein-ligand binding free energy based on molecular dynamics (MD) simulations generally relies on a thermodynamic cycle in which the ligand is alchemically inserted into the system, both in the solvated protein and free in solution. The corresponding ligand-insertion free energies are typically calculated in nanoscale computational boxes simulated under periodic boundary conditions and considering electrostatic interactions defined by a periodic lattice-sum. This is distinct from the ideal bulk situation of a system of macroscopic size simulated under non-periodic boundary conditions with Coulombic electrostatic interactions. This discrepancy results in finite-size effects, which affect primarily the charging component of the insertion free energy, are dependent on the box size, and can be large when the ligand bears a net charge, especially if the protein is charged as well. This article investigates finite-size effects on calculated charging free energies using as a test case the binding of the ligand 2-amino-5-methylthiazole (net charge +1 e) to a mutant form of yeast cytochrome c peroxidase in water. Considering different charge isoforms of the protein (net charges −5, 0, +3, or +9 e), either in the absence or the presence of neutralizing counter-ions, and sizes of the cubic computational box (edges ranging from 7.42 to 11.02 nm), the potentially large magnitude of finite-size effects on the raw charging free energies (up to 17.1 kJ mol{sup −1}) is demonstrated. Two correction schemes are then proposed to eliminate these effects, a numerical and an analytical one. Both schemes are based on a continuum-electrostatics analysis and require performing Poisson-Boltzmann (PB) calculations on the protein-ligand system. While the numerical scheme requires PB calculations under both non-periodic and periodic boundary conditions, the latter at the box size considered in the MD simulations, the analytical scheme only requires three non
Rocklin, Gabriel J.; Mobley, David L.; Dill, Ken A.; Hünenberger, Philippe H.
2013-11-01
The calculation of a protein-ligand binding free energy based on molecular dynamics (MD) simulations generally relies on a thermodynamic cycle in which the ligand is alchemically inserted into the system, both in the solvated protein and free in solution. The corresponding ligand-insertion free energies are typically calculated in nanoscale computational boxes simulated under periodic boundary conditions and considering electrostatic interactions defined by a periodic lattice-sum. This is distinct from the ideal bulk situation of a system of macroscopic size simulated under non-periodic boundary conditions with Coulombic electrostatic interactions. This discrepancy results in finite-size effects, which affect primarily the charging component of the insertion free energy, are dependent on the box size, and can be large when the ligand bears a net charge, especially if the protein is charged as well. This article investigates finite-size effects on calculated charging free energies using as a test case the binding of the ligand 2-amino-5-methylthiazole (net charge +1 e) to a mutant form of yeast cytochrome c peroxidase in water. Considering different charge isoforms of the protein (net charges -5, 0, +3, or +9 e), either in the absence or the presence of neutralizing counter-ions, and sizes of the cubic computational box (edges ranging from 7.42 to 11.02 nm), the potentially large magnitude of finite-size effects on the raw charging free energies (up to 17.1 kJ mol-1) is demonstrated. Two correction schemes are then proposed to eliminate these effects, a numerical and an analytical one. Both schemes are based on a continuum-electrostatics analysis and require performing Poisson-Boltzmann (PB) calculations on the protein-ligand system. While the numerical scheme requires PB calculations under both non-periodic and periodic boundary conditions, the latter at the box size considered in the MD simulations, the analytical scheme only requires three non-periodic PB
Alternative energy technologies an introduction with computer simulations
Buxton, Gavin
2014-01-01
Introduction to Alternative Energy SourcesGlobal WarmingPollutionSolar CellsWind PowerBiofuelsHydrogen Production and Fuel CellsIntroduction to Computer ModelingBrief History of Computer SimulationsMotivation and Applications of Computer ModelsUsing Spreadsheets for SimulationsTyping Equations into SpreadsheetsFunctions Available in SpreadsheetsRandom NumbersPlotting DataMacros and ScriptsInterpolation and ExtrapolationNumerical Integration and Diffe
Collaborative simulation method with spatiotemporal synchronization process control
Zou, Yisheng; Ding, Guofu; Zhang, Weihua; Zhang, Jian; Qin, Shengfeng; Tan, John Kian
2016-10-01
When designing a complex mechatronics system, such as high speed trains, it is relatively difficult to effectively simulate the entire system's dynamic behaviors because it involves multi-disciplinary subsystems. Currently,a most practical approach for multi-disciplinary simulation is interface based coupling simulation method, but it faces a twofold challenge: spatial and time unsynchronizations among multi-directional coupling simulation of subsystems. A new collaborative simulation method with spatiotemporal synchronization process control is proposed for coupling simulating a given complex mechatronics system across multiple subsystems on different platforms. The method consists of 1) a coupler-based coupling mechanisms to define the interfacing and interaction mechanisms among subsystems, and 2) a simulation process control algorithm to realize the coupling simulation in a spatiotemporal synchronized manner. The test results from a case study show that the proposed method 1) can certainly be used to simulate the sub-systems interactions under different simulation conditions in an engineering system, and 2) effectively supports multi-directional coupling simulation among multi-disciplinary subsystems. This method has been successfully applied in China high speed train design and development processes, demonstrating that it can be applied in a wide range of engineering systems design and simulation with improved efficiency and effectiveness.
Comparison of vibrational conductivity and radiative energy transfer methods
Le Bot, A.
2005-05-01
This paper is concerned with the comparison of two methods well suited for the prediction of the wideband response of built-up structures subjected to high-frequency vibrational excitation. The first method is sometimes called the vibrational conductivity method and the second one is rather known as the radiosity method in the field of acoustics, or the radiative energy transfer method. Both are based on quite similar physical assumptions i.e. uncorrelated sources, mean response and high-frequency excitation. Both are based on analogies with some equations encountered in the field of heat transfer. However these models do not lead to similar results. This paper compares the two methods. Some numerical simulations on a pair of plates joined along one edge are provided to illustrate the discussion.
Math-Based Simulation Tools and Methods
National Research Council Canada - National Science Library
Arepally, Sudhakar
2007-01-01
.... The following methods are reviewed: matrix operations, ordinary and partial differential system of equations, Lagrangian operations, Fourier transforms, Taylor Series, Finite Difference Methods, implicit and explicit finite element...
Dark Energy Studies with LSST Image Simulations, Final Report
International Nuclear Information System (INIS)
Peterson, John Russell
2016-01-01
This grant funded the development and dissemination of the Photon Simulator (PhoSim) for the purpose of studying dark energy at high precision with the upcoming Large Synoptic Survey Telescope (LSST) astronomical survey. The work was in collaboration with the LSST Dark Energy Science Collaboration (DESC). Several detailed physics improvements were made in the optics, atmosphere, and sensor, a number of validation studies were performed, and a significant number of usability features were implemented. Future work in DESC will use PhoSim as the image simulation tool for data challenges used by the analysis groups.
International Nuclear Information System (INIS)
Liang, Hongbo; Fan, Man; You, Shijun; Zheng, Wandong; Zhang, Huan; Ye, Tianzhen; Zheng, Xuejing
2017-01-01
Highlights: •Four optical models for parabolic trough solar collectors were compared in detail. •Characteristics of Monte Carlo Method and Finite Volume Method were discussed. •A novel method was presented combining advantages of different models. •The method was suited to optical analysis of collectors with different geometries. •A new kind of cavity receiver was simulated depending on the novel method. -- Abstract: The PTC (parabolic trough solar collector) is widely used for space heating, heat-driven refrigeration, solar power, etc. The concentrated solar radiation is the only energy source for a PTC, thus its optical performance significantly affects the collector efficiency. In this study, four different optical models were constructed, validated and compared in detail. On this basis, a novel coupled method was presented by combining advantages of these models, which was suited to carry out a mass of optical simulations of collectors with different geometrical parameters rapidly and accurately. Based on these simulation results, the optimal configuration of a collector with highest efficiency can be determined. Thus, this method was useful for collector optimization and design. In the four models, MCM (Monte Carlo Method) and FVM (Finite Volume Method) were used to initialize photons distribution, as well as CPEM (Change Photon Energy Method) and MCM were adopted to describe the process of reflecting, transmitting and absorbing. For simulating reflection, transmission and absorption, CPEM was more efficient than MCM, so it was utilized in the coupled method. For photons distribution initialization, FVM saved running time and computation effort, whereas it needed suitable grid configuration. MCM only required a total number of rays for simulation, whereas it needed higher computing cost and its results fluctuated in multiple runs. In the novel coupled method, the grid configuration for FVM was optimized according to the “true values” from MCM of
Building Performance Simulation tools for planning of energy efficiency retrofits
DEFF Research Database (Denmark)
Mondrup, Thomas Fænø; Karlshøj, Jan; Vestergaard, Flemming
2014-01-01
Designing energy efficiency retrofits for existing buildings will bring environmental, economic, social, and health benefits. However, selecting specific retrofit strategies is complex and requires careful planning. In this study, we describe a methodology for adopting Building Performance...... to energy efficiency retrofits in social housing. To generate energy savings, we focus on optimizing the building envelope. We evaluate alternative building envelope actions using procedural solar radiation and daylight simulations. In addition, we identify the digital information flow and the information...... Simulation (BPS) tools as energy and environmentally conscious decision-making aids. The methodology has been developed to screen buildings for potential improvements and to support the development of retrofit strategies. We present a case study of a Danish renovation project, implementing BPS approaches...
Contrasting the capabilities of building energy performance simulation programs
Energy Technology Data Exchange (ETDEWEB)
Crawley, Drury B. [US Department of Energy, Washington, DC (United States); Hand, Jon W. [University of Strathclyde, Glasgow, Scotland (United Kingdom). Energy Systems Research Unit; Kummert, Michael [University of Wisconsin-Madison (United States). Solar Energy Laboratory; Griffith, Brent T. [National Renewable Energy Laboratory, Golden, CO (United States)
2008-04-15
For the past 50 years, a wide variety of building energy simulation programs have been developed, enhanced and are in use throughout the building energy community. This paper is an overview of a report, which provides up-to-date comparison of the features and capabilities of twenty major building energy simulation programs. The comparison is based on information provided by the program developers in the following categories: general modeling features; zone loads; building envelope and daylighting and solar; infiltration, ventilation and multizone airflow; renewable energy systems; electrical systems and equipment; HVAC systems; HVAC equipment; environmental emissions; economic evaluation; climate data availability, results reporting; validation; and user interface, links to other programs, and availability. (author)
Simulation-based support for integrated design of new low-energy office buildings
DEFF Research Database (Denmark)
Petersen, Steffen
. The method uses the energy frame concept to express the constraints of the optimisation problem, which is then solved by minimising the costs of conserving energy in all the individual energy-saving measures. A case example illustrates how the method enables designers to establish a qualified estimate...... a method for making informed decisions in the early stages of building design to fulfil performance requirements with regard to energy consumption and indoor environment. The method is operationalised in a program that utilises a simple simulation program to make performance predictions of user......-defined parameter variations. The program then presents the output in a way that enables designers to make informed decisions. The method and the program reduce the need for design iterations, reducing time consumption and construction costs, to obtain the intended energy performance and indoor environment. Paper...
Energy efficient process planning based on numerical simulations
Neugebauer, Reimund; Hochmuth, C.; Schmidt, G.; Dix, M.
2011-01-01
The main goal of energy-efficient manufacturing is to generate products with maximum value-added at minimum energy consumption. To this end, in metal cutting processes, it is necessary to reduce the specific cutting energy while, at the same time, precision requirements have to be ensured. Precision is critical in metal cutting processes because they often constitute the final stages of metalworking chains. This paper presents a method for the planning of energy-efficient machining processes ...
Spacecraft Dynamic Characterization by Strain Energies Method
Bretagne, J.-M.; Fragnito, M.; Massier, S.
2002-01-01
In the last years the significant increase in satellite broadcasting demand, with the wide band communication dawn, has given a great impulse to the telecommunication satellite market. The big demand is translated from operators (such as SES/Astra, Eutelsat, Intelsat, Inmarsat, EuroSkyWay etc.) in an increase of orders of telecom satellite to the world industrials. The largest part of these telecom satellite orders consists of Geostationary platforms which grow more and more in mass (over 5 tons) due to an ever longer demanded lifetime (up to 20 years), and become more complex due to the need of implementing an ever larger number of repeaters, antenna reflectors and feeds, etc... In this frame, the mechanical design and verification of these large spacecraft become difficult and ambitious at the same time, driven by the dry mass limitation objective. By the Finite Element Method (FEM), and on the basis of the telecom satellite heritage of a world leader constructor such as Alcatel Space Industries it is nowadays possible to model these spacecraft in a realistic and confident way in order to identify the main global dynamic aspects such as mode shapes, mass participation and/or dynamic responses. But on the other hand, one of the main aims consists in identifying soon in a program the most critical aspects of the system behavior in the launch dynamic environment, such as possible dynamic coupling between the different subsystems and secondary structures of the spacecraft (large deployable reflectors, thrusters, etc.). To this aim a numerical method has been developed in the frame of the Alcatel SPACEBUS family program, using MSC/Nastran capabilities and it is presented in this paper. The method is based on Spacecraft sub-structuring and strain energy calculation. The method mainly consists of two steps : 1) subsystem modal strain energy ratio (with respect to the global strain energy); 2) subsystem strain energy calculation for each mode according to the base driven
Simulation of bubble motion under gravity by lattice Boltzmann method
International Nuclear Information System (INIS)
Takada, Naoki; Misawa, Masaki; Tomiyama, Akio; Hosokawa, Shigeo
2001-01-01
We describe the numerical simulation results of bubble motion under gravity by the lattice Boltzmann method (LBM), which assumes that a fluid consists of mesoscopic fluid particles repeating collision and translation and a multiphase interface is reproduced in a self-organizing way by repulsive interaction between different kinds of particles. The purposes in this study are to examine the applicability of LBM to the numerical analysis of bubble motions, and to develop a three-dimensional version of the binary fluid model that introduces a free energy function. We included the buoyancy terms due to the density difference in the lattice Boltzmann equations, and simulated single-and two-bubble motions, setting flow conditions according to the Eoetvoes and Morton numbers. The two-dimensional results by LBM agree with those by the Volume of Fluid method based on the Navier-Stokes equations. The three-dimensional model possesses the surface tension satisfying the Laplace's law, and reproduces the motion of single bubble and the two-bubble interaction of their approach and coalescence in circular tube. There results prove that the buoyancy terms and the 3D model proposed here are suitable, and that LBM is useful for the numerical analysis of bubble motion under gravity. (author)
Research methods of simulate digital compensators and autonomous control systems
Directory of Open Access Journals (Sweden)
V. S. Kudryashov
2016-01-01
Full Text Available The peculiarity of the present stage of development of the production is the need to control and regulate a large number of process parameters, the mutual influence on each other that when using single-circuit systems significantly reduces the quality of the transition process, resulting in significant costs of raw materials and energy, reduce the quality of the products. Using a stand-alone digital control system eliminates the correlation of technological parameters, to give the system the desired dynamic and static properties, improve the quality of regulation. However, the complexity of the configuration and implementation of procedures (modeling compensators autonomous systems of this type, associated with the need to perform a significant amount of complex analytic transformation significantly limit the scope of their application. In this regard, the approach based on the decompo sition proposed methods of calculation and simulation (realization, consisting in submitting elements autonomous control part digital control system in a series parallel connection. The above theoretical study carried out in a general way for any dimension systems. The results of computational experiments, obtained during the simulation of the four autonomous control systems, comparative analysis and conclusions on the effectiveness of the use of each of the methods. The results obtained can be used in the development of multi-dimensional process control systems.
Examining ion channel properties using free-energy methods.
Domene, Carmen; Furini, Simone
2009-01-01
Recent advances in structural biology have revealed the architecture of a number of transmembrane channels, allowing for these complex biological systems to be understood in atomistic detail. Computational simulations are a powerful tool by which the dynamic and energetic properties, and thereby the function of these protein architectures, can be investigated. The experimentally observable properties of a system are often determined more by energetic than dynamics, and therefore understanding the underlying free energy (FE) of biophysical processes is of crucial importance. Critical to the accurate evaluation of FE values are the problems of obtaining accurate sampling of complex biological energy landscapes, and of obtaining accurate representations of the potential energy of a system, this latter problem having been addressed through the development of molecular force fields. While these challenges are common to all FE methods, depending on the system under study, and the questions being asked of it, one technique for FE calculation may be preferable to another, the choice of method and simulation protocol being crucial to achieve efficiency. Applied in a correct manner, FE calculations represent a predictive and affordable computational tool with which to make relevant contact with experiments. This chapter, therefore, aims to give an overview of the most widely implemented computational methods used to calculate the FE associated with particular biochemical or biophysical events, and to highlight their recent applications to ion channels. Copyright © 2009 Elsevier Inc. All rights reserved.
Interactive methods for exploring particle simulation data
Energy Technology Data Exchange (ETDEWEB)
Co, Christopher S.; Friedman, Alex; Grote, David P.; Vay, Jean-Luc; Bethel, E. Wes; Joy, Kenneth I.
2004-05-01
In this work, we visualize high-dimensional particle simulation data using a suite of scatter plot-based visualizations coupled with interactive selection tools. We use traditional 2D and 3D projection scatter plots as well as a novel oriented disk rendering style to convey various information about the data. Interactive selection tools allow physicists to manually classify ''interesting'' sets of particles that are highlighted across multiple, linked views of the data. The power of our application is the ability to correspond new visual representations of the simulation data with traditional, well understood visualizations. This approach supports the interactive exploration of the high-dimensional space while promoting discovery of new particle behavior.
Hospital Registration Process Reengineering Using Simulation Method
Directory of Open Access Journals (Sweden)
Qiang Su
2010-01-01
Full Text Available With increasing competition, many healthcare organizations have undergone tremendous reform in the last decade aiming to increase efficiency, decrease waste, and reshape the way that care is delivered. This study focuses on the operational efficiency improvement of hospital’s registration process. The operational efficiency related factors including the service process, queue strategy, and queue parameters were explored systematically and illustrated with a case study. Guided by the principle of business process reengineering (BPR, a simulation approach was employed for process redesign and performance optimization. As a result, the queue strategy is changed from multiple queues and multiple servers to single queue and multiple servers with a prepare queue. Furthermore, through a series of simulation experiments, the length of the prepare queue and the corresponding registration process efficiency was quantitatively evaluated and optimized.
Hybrid Simulation Modeling to Estimate U.S. Energy Elasticities
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.
International Nuclear Information System (INIS)
Song, Junnian; Yang, Wei; Higano, Yoshiro; Wang, Xian’en
2015-01-01
Highlights: • Renewable energy development is expanded and introduced into socioeconomic activities. • A dynamic optimization simulation model is developed based on input–output approach. • Regional economic, energy and environmental impacts are assessed dynamically. • Industrial and energy structure is adjusted optimally for GHG emission reduction. - Abstract: Specifying the renewable energy development as new energy industries to be newly introduced into current socioeconomic activities, this study develops a dynamic simulation model with input–output approach to make comprehensive assessment of the impacts on economic development, energy consumption and GHG emission under distinct levels of GHG emission constraints involving targeted GHG emission reduction policies (ERPs) and industrial restructuring. The model is applied to Jilin City to conduct 16 terms of dynamic simulation work with GRP as objective function subject to mass, value and energy balances aided by the extended input–output table with renewable energy industries introduced. Simulation results indicate that achievement of GHG emission reduction target is contributed by renewable energy industries, ERPs and industrial restructuring collectively, which reshape the terminal energy consumption structure with a larger proportion of renewable energy. Wind power, hydropower and biomass combustion power industries account for more in the power generation structure implying better industrial prospects. Mining, chemical, petroleum processing, non-metal, metal and thermal power industries are major targets for industrial restructuring. This method is crucial for understanding the role of renewable energy development in GHG mitigation efforts and other energy-related planning settings, allowing to explore the optimal level for relationships among all socioeconomic activities and facilitate to simultaneous pursuit of economic development, energy utilization and environmental preservation
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.
Teaching simulator for divulgation of the nuclear energy
International Nuclear Information System (INIS)
Ortega B, M.G.; Gutierrez F, R.
2003-01-01
To solicitude of the authorities of the 'Universum' sciences museum of the UNAM, it develops a highly interactive computational system, to provide of information to the population in general about basic principles, uses and benefits of the nuclear energy. The objective is to achieve a better understanding and acceptance of the nuclear technology in our country. The system allows the visualization and simulation of nuclear processes as well as of its applications. The system is divided in three levels: basic, intermediate and simulation. In the basic level multimedia information is included on diverse basic concepts of the nuclear energy. The intermediate level includes the description and operation of some systems of the Laguna Verde nuclear power plant (CNLV). Finally the simulation level contains representative scenarios that the user can control by means of virtual control panels of the main systems of the CNLV. Inside the system a part of interactive games is included with the purpose that the user remembers with more easiness all the concepts and advantages of the nuclear energy mentioned during the previous levels. The system contributes, by means of the development of multimedia computational tools and of simulation, to the popularization of the use and applications of the nuclear energy in Mexico. (Author)
Molecular dynamics simulations and free energy profile of ...
Indian Academy of Sciences (India)
aDepartment of Chemical Engineering, bDepartment of Chemistry, Amirkabir University of Technology,. 15875-4413 ... Lipid bilayers; Paracetamol; free energy; molecular dynamics simulation; membrane. 1. ..... bilayer is less favourable due to the hydrophobic nature .... Orsi M and Essex J W 2010 Soft Matter 6 3797. 54.
MALAYSIAN WEATHER DATA (TRY) FOR ENERGY SIMULATIONS IN BUILDINGS
DEFF Research Database (Denmark)
Reimann, Gregers Peter
2001-01-01
Detailed energy simulations for buildings in Malaysia have become possible after the recent construction of a Malaysian TRY (Test Reference Year) based on 21 years of hourly weather data from Subang Meteorological Station. The climatic parameters contained in the TRY are dry bulb temperature, wet...
BRUS2. An energy system simulator for long term planning
DEFF Research Database (Denmark)
Skytte, K.; Skjerk Christensen, P.
1999-01-01
BRUS2 is a technical-economic bottom-up scenario model. The objective of BRUS2 is to provide decision-makers with information on consequences of given trends of parameters of society like population growth and productivity, and of political goals, e.g., energy saving initiatives. BRUS2 simulates ...
International Nuclear Information System (INIS)
Sakane, Shinichi; Yezdimer, Eric M.; Liu, Wenbin; Barriocanal, Jose A.; Doren, Douglas J.; Wood, Robert H.
2000-01-01
The ab initio/classical free energy perturbation (ABC-FEP) method proposed previously by Wood et al. [J. Chem. Phys. 110, 1329 (1999)] uses classical simulations to calculate solvation free energies within an empirical potential model, then applies free energy perturbation theory to determine the effect of changing the empirical solute-solvent interactions to corresponding interactions calculated from ab initio methods. This approach allows accurate calculation of solvation free energies using an atomistic description of the solvent and solute, with interactions calculated from first principles. Results can be obtained at a feasible computational cost without making use of approximations such as a continuum solvent or an empirical cavity formation energy. As such, the method can be used far from ambient conditions, where the empirical parameters needed for approximate theories of solvation may not be available. The sources of error in the ABC-FEP method are the approximations in the ab initio method, the finite sample of configurations, and the classical solvent model. This article explores the accuracy of various approximations used in the ABC-FEP method by comparing to the experimentally well-known free energy of hydration of water at two state points (ambient conditions, and 973.15 K and 600 kg/m3). The TIP4P-FQ model [J. Chem. Phys. 101, 6141 (1994)] is found to be a reliable solvent model for use with this method, even at supercritical conditions. Results depend strongly on the ab initio method used: a gradient-corrected density functional theory is not adequate, but a localized MP2 method yields excellent agreement with experiment. Computational costs are reduced by using a cluster approximation, in which ab initio pair interaction energies are calculated between the solute and up to 60 solvent molecules, while multi-body interactions are calculated with only a small cluster (5 to 12 solvent molecules). Sampling errors for the ab initio contribution to
Gradient augmented level set method for phase change simulations
Anumolu, Lakshman; Trujillo, Mario F.
2018-01-01
A numerical method for the simulation of two-phase flow with phase change based on the Gradient-Augmented-Level-set (GALS) strategy is presented. Sharp capturing of the vaporization process is enabled by: i) identification of the vapor-liquid interface, Γ (t), at the subgrid level, ii) discontinuous treatment of thermal physical properties (except for μ), and iii) enforcement of mass, momentum, and energy jump conditions, where the gradients of the dependent variables are obtained at Γ (t) and are consistent with their analytical expression, i.e. no local averaging is applied. Treatment of the jump in velocity and pressure at Γ (t) is achieved using the Ghost Fluid Method. The solution of the energy equation employs the sub-grid knowledge of Γ (t) to discretize the temperature Laplacian using second-order one-sided differences, i.e. the numerical stencil completely resides within each respective phase. To carefully evaluate the benefits or disadvantages of the GALS approach, the standard level set method is implemented and compared against the GALS predictions. The results show the expected trend that interface identification and transport are predicted noticeably better with GALS over the standard level set. This benefit carries over to the prediction of the Laplacian and temperature gradients in the neighborhood of the interface, which are directly linked to the calculation of the vaporization rate. However, when combining the calculation of interface transport and reinitialization with two-phase momentum and energy, the benefits of GALS are to some extent neutralized, and the causes for this behavior are identified and analyzed. Overall the additional computational costs associated with GALS are almost the same as those using the standard level set technique.
Numerical simulation for cracks detection using the finite elements method
Directory of Open Access Journals (Sweden)
S Bennoud
2016-09-01
Full Text Available The means of detection must ensure controls either during initial construction, or at the time of exploitation of all parts. The Non destructive testing (NDT gathers the most widespread methods for detecting defects of a part or review the integrity of a structure. In the areas of advanced industry (aeronautics, aerospace, nuclear …, assessing the damage of materials is a key point to control durability and reliability of parts and materials in service. In this context, it is necessary to quantify the damage and identify the different mechanisms responsible for the progress of this damage. It is therefore essential to characterize materials and identify the most sensitive indicators attached to damage to prevent their destruction and use them optimally. In this work, simulation by finite elements method is realized with aim to calculate the electromagnetic energy of interaction: probe and piece (with/without defect. From calculated energy, we deduce the real and imaginary components of the impedance which enables to determine the characteristic parameters of a crack in various metallic parts.
A New Model to Simulate Energy Performance of VRF Systems
Energy Technology Data Exchange (ETDEWEB)
Hong, Tianzhen; Pang, Xiufeng; Schetrit, Oren; Wang, Liping; Kasahara, Shinichi; Yura, Yoshinori; Hinokuma, Ryohei
2014-03-30
This paper presents a new model to simulate energy performance of variable refrigerant flow (VRF) systems in heat pump operation mode (either cooling or heating is provided but not simultaneously). The main improvement of the new model is the introduction of the evaporating and condensing temperature in the indoor and outdoor unit capacity modifier functions. The independent variables in the capacity modifier functions of the existing VRF model in EnergyPlus are mainly room wet-bulb temperature and outdoor dry-bulb temperature in cooling mode and room dry-bulb temperature and outdoor wet-bulb temperature in heating mode. The new approach allows compliance with different specifications of each indoor unit so that the modeling accuracy is improved. The new VRF model was implemented in a custom version of EnergyPlus 7.2. This paper first describes the algorithm for the new VRF model, which is then used to simulate the energy performance of a VRF system in a Prototype House in California that complies with the requirements of Title 24 ? the California Building Energy Efficiency Standards. The VRF system performance is then compared with three other types of HVAC systems: the Title 24-2005 Baseline system, the traditional High Efficiency system, and the EnergyStar Heat Pump system in three typical California climates: Sunnyvale, Pasadena and Fresno. Calculated energy savings from the VRF systems are significant. The HVAC site energy savings range from 51 to 85percent, while the TDV (Time Dependent Valuation) energy savings range from 31 to 66percent compared to the Title 24 Baseline Systems across the three climates. The largest energy savings are in Fresno climate followed by Sunnyvale and Pasadena. The paper discusses various characteristics of the VRF systems contributing to the energy savings. It should be noted that these savings are calculated using the Title 24 prototype House D under standard operating conditions. Actual performance of the VRF systems for real
Benchmarking HRA methods against different NPP simulator data
International Nuclear Information System (INIS)
Petkov, Gueorgui; Filipov, Kalin; Velev, Vladimir; Grigorov, Alexander; Popov, Dimiter; Lazarov, Lazar; Stoichev, Kosta
2008-01-01
The paper presents both international and Bulgarian experience in assessing HRA methods, underlying models approaches for their validation and verification by benchmarking HRA methods against different NPP simulator data. The organization, status, methodology and outlooks of the studies are described
Clarke, Peter; Varghese, Philip; Goldstein, David
2018-01-01
A discrete velocity method is developed for gas mixtures of diatomic molecules with both rotational and vibrational energy states. A full quantized model is described, and rotation-translation and vibration-translation energy exchanges are simulated using a Larsen-Borgnakke exchange model. Elastic and inelastic molecular interactions are modeled during every simulated collision to help produce smooth internal energy distributions. The method is verified by comparing simulations of homogeneous relaxation by our discrete velocity method to numerical solutions of the Jeans and Landau-Teller equations, and to direct simulation Monte Carlo. We compute the structure of a 1D shock using this method, and determine how the rotational energy distribution varies with spatial location in the shock and with position in velocity space.
Math-Based Simulation Tools and Methods
National Research Council Canada - National Science Library
Arepally, Sudhakar
2007-01-01
...: HMMWV 30-mph Rollover Test, Soldier Gear Effects, Occupant Performance in Blast Effects, Anthropomorphic Test Device, Human Models, Rigid Body Modeling, Finite Element Methods, Injury Criteria...
Particle-transport simulation with the Monte Carlo method
International Nuclear Information System (INIS)
Carter, L.L.; Cashwell, E.D.
1975-01-01
Attention is focused on the application of the Monte Carlo method to particle transport problems, with emphasis on neutron and photon transport. Topics covered include sampling methods, mathematical prescriptions for simulating particle transport, mechanics of simulating particle transport, neutron transport, and photon transport. A literature survey of 204 references is included. (GMT)
Calibrating a combined energy systems analysis and controller design method with empirical data
International Nuclear Information System (INIS)
Murphy, Gavin Bruce; Counsell, John; Allison, John; Brindley, Joseph
2013-01-01
The drive towards low carbon constructions has seen buildings increasingly utilise many different energy systems simultaneously to control the human comfort of the indoor environment; such as ventilation with heat recovery, various heating solutions and applications of renewable energy. This paper describes a dynamic modelling and simulation method (IDEAS – Inverse Dynamics based Energy Assessment and Simulation) for analysing the energy utilisation of a building and its complex servicing systems. The IDEAS case study presented in this paper is based upon small perturbation theory and can be used for the analysis of the performance of complex energy systems and also for the design of smart control systems. This paper presents a process of how any dynamic model can be calibrated against a more empirical based data model, in this case the UK Government's SAP (Standard Assessment Procedure). The research targets of this work are building simulation experts for analysing the energy use of a building and also control engineers to assist in the design of smart control systems for dwellings. The calibration process presented is transferable and has applications for simulation experts to assist in calibrating any dynamic building simulation method with an empirical based method. - Highlights: • Presentation of an energy systems analysis method for assessing the energy utilisation of buildings and their complex servicing systems. • An inverse dynamics based controller design method is detailed. • Method of how a dynamic model can be calibrated with an empirical based model
Real-time hybrid simulation using the convolution integral method
International Nuclear Information System (INIS)
Kim, Sung Jig; Christenson, Richard E; Wojtkiewicz, Steven F; Johnson, Erik A
2011-01-01
This paper proposes a real-time hybrid simulation method that will allow complex systems to be tested within the hybrid test framework by employing the convolution integral (CI) method. The proposed CI method is potentially transformative for real-time hybrid simulation. The CI method can allow real-time hybrid simulation to be conducted regardless of the size and complexity of the numerical model and for numerical stability to be ensured in the presence of high frequency responses in the simulation. This paper presents the general theory behind the proposed CI method and provides experimental verification of the proposed method by comparing the CI method to the current integration time-stepping (ITS) method. Real-time hybrid simulation is conducted in the Advanced Hazard Mitigation Laboratory at the University of Connecticut. A seismically excited two-story shear frame building with a magneto-rheological (MR) fluid damper is selected as the test structure to experimentally validate the proposed method. The building structure is numerically modeled and simulated, while the MR damper is physically tested. Real-time hybrid simulation using the proposed CI method is shown to provide accurate results
Simulation of tunneling construction methods of the Cisumdawu toll road
Abduh, Muhamad; Sukardi, Sapto Nugroho; Ola, Muhammad Rusdian La; Ariesty, Anita; Wirahadikusumah, Reini D.
2017-11-01
Simulation can be used as a tool for planning and analysis of a construction method. Using simulation technique, a contractor could design optimally resources associated with a construction method and compare to other methods based on several criteria, such as productivity, waste, and cost. This paper discusses the use of simulation using Norwegian Method of Tunneling (NMT) for a 472-meter tunneling work in the Cisumdawu Toll Road project. Primary and secondary data were collected to provide useful information for simulation as well as problems that may be faced by the contractor. The method was modelled using the CYCLONE and then simulated using the WebCYCLONE. The simulation could show the duration of the project from the duration model of each work tasks which based on literature review, machine productivity, and several assumptions. The results of simulation could also show the total cost of the project that was modeled based on journal construction & building unit cost and online websites of local and international suppliers. The analysis of the advantages and disadvantages of the method was conducted based on its, wastes, and cost. The simulation concluded the total cost of this operation is about Rp. 900,437,004,599 and the total duration of the tunneling operation is 653 days. The results of the simulation will be used for a recommendation to the contractor before the implementation of the already selected tunneling operation.
Workshop on data acquisition and trigger system simulations for high energy physics
International Nuclear Information System (INIS)
1992-01-01
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 ampersand The Design of a Queue for this Circuit; Fast Data Compression ampersand 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 ampersand Online Processing at the SSC; Planned Enhancements to MODSEM II ampersand SIMOBJECT -- an 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
Workshop on data acquisition and trigger system simulations for high energy physics
Energy Technology Data Exchange (ETDEWEB)
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 -- an 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.
Large Eddy Simulation of Turbulent Flows in Wind Energy
DEFF Research Database (Denmark)
Chivaee, Hamid Sarlak
This research is devoted to the Large Eddy Simulation (LES), and to lesser extent, wind tunnel measurements of turbulent flows in wind energy. It starts with an introduction to the LES technique associated with the solution of the incompressible Navier-Stokes equations, discretized using a finite......, should the mesh resolution, numerical discretization scheme, time averaging period, and domain size be chosen wisely. A thorough investigation of the wind turbine wake interactions is also conducted and the simulations are validated against available experimental data from external sources. The effect...... Reynolds numbers, and thereafter, the fully-developed infinite wind farm boundary later simulations are performed. Sources of inaccuracy in the simulations are investigated and it is found that high Reynolds number flows are more sensitive to the choice of the SGS model than their low Reynolds number...
Simulation of off-energy electron background in DELPHI
Falk, E; Von Holtey, Georg
1997-01-01
Monte Carlo simulations of off-energy electron background in the DELPHI luminometer STIC are reported. The study simulates the running conditions at 68 GeV with and without bunch trains. The electrostatic separators, which create the vertical separation bumps for the the bunch trains, cause a high concentration of background in the vertical plane. The simulations are compared to LEP data taken under similar running conditions. A comparison between the simulated running conditions at 68 GeV and those of the new LEP2 beam optics at 80.5 GeV is made. Moreover, the study investigates background components entering STIC elsewhere that through the front of the detector, and a significant portion is found to enter either from the back or from below. Possible improvements of the background situation are also discussed.
Interval sampling methods and measurement error: a computer simulation.
Wirth, Oliver; Slaven, James; Taylor, Matthew A
2014-01-01
A simulation study was conducted to provide a more thorough account of measurement error associated with interval sampling methods. A computer program simulated the application of momentary time sampling, partial-interval recording, and whole-interval recording methods on target events randomly distributed across an observation period. The simulation yielded measures of error for multiple combinations of observation period, interval duration, event duration, and cumulative event duration. The simulations were conducted up to 100 times to yield measures of error variability. Although the present simulation confirmed some previously reported characteristics of interval sampling methods, it also revealed many new findings that pertain to each method's inherent strengths and weaknesses. The analysis and resulting error tables can help guide the selection of the most appropriate sampling method for observation-based behavioral assessments. © Society for the Experimental Analysis of Behavior.
Study on low-energy sputtering near the threshold energy by molecular dynamics simulations
Directory of Open Access Journals (Sweden)
C. Yan
2012-09-01
Full Text Available Using molecular dynamics simulation, we have studied the low-energy sputtering at the energies near the sputtering threshold. Different projectile-target combinations of noble metal atoms (Cu, Ag, Au, Ni, Pd, and Pt are simulated in the range of incident energy from 0.1 to 200 eV. It is found that the threshold energies for sputtering are different for the cases of M1 < M2 and M1 ≥ M2, where M1 and M2 are atomic mass of projectile and target atoms, respectively. The sputtering yields are found to have a linear dependence on the reduced incident energy, but the dependence behaviors are different for the both cases. The two new formulas are suggested to describe the energy dependences of the both cases by fitting the simulation results with the determined threshold energies. With the study on the energy dependences of sticking probabilities and traces of the projectiles and recoils, we propose two different mechanisms to describe the sputtering behavior of low-energy atoms near the threshold energy for the cases of M1 < M2 and M1 ≥ M2, respectively.
The frontal method in hydrodynamics simulations
Walters, R.A.
1980-01-01
The frontal solution method has proven to be an effective means of solving the matrix equations resulting from the application of the finite element method to a variety of problems. In this study, several versions of the frontal method were compared in efficiency for several hydrodynamics problems. Three basic modifications were shown to be of value: 1. Elimination of equations with boundary conditions beforehand, 2. Modification of the pivoting procedures to allow dynamic management of the equation size, and 3. Storage of the eliminated equations in a vector. These modifications are sufficiently general to be applied to other classes of problems. ?? 1980.
Simulated galaxy interactions as probes of merger spectral energy distributions
Energy Technology Data Exchange (ETDEWEB)
Lanz, Lauranne; Zezas, Andreas; Smith, Howard A.; Ashby, Matthew L. N.; Fazio, Giovanni G.; Hernquist, Lars [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Hayward, Christopher C. [Heidelberger Institut für Theoretische Studien, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany); Brassington, Nicola, E-mail: llanz@ipac.caltech.edu [School of Physics, Astronomy and Mathematics, University of Hertfordshire, College Lane, Hatfield, AL10 9AB (United Kingdom)
2014-04-10
We present the first systematic comparison of ultraviolet-millimeter spectral energy distributions (SEDs) of observed and simulated interacting galaxies. Our sample is drawn from the Spitzer Interacting Galaxy Survey and probes a range of galaxy interaction parameters. We use 31 galaxies in 14 systems which have been observed with Herschel, Spitzer, GALEX, and 2MASS. We create a suite of GADGET-3 hydrodynamic simulations of isolated and interacting galaxies with stellar masses comparable to those in our sample of interacting galaxies. Photometry for the simulated systems is then calculated with the SUNRISE radiative transfer code for comparison with the observed systems. For most of the observed systems, one or more of the simulated SEDs match reasonably well. The best matches recover the infrared luminosity and the star formation rate of the observed systems, and the more massive systems preferentially match SEDs from simulations of more massive galaxies. The most morphologically distorted systems in our sample are best matched to the simulated SEDs that are close to coalescence, while less evolved systems match well with the SEDs over a wide range of interaction stages, suggesting that an SED alone is insufficient for identifying the interaction stage except during the most active phases in strongly interacting systems. This result is supported by our finding that the SEDs calculated for simulated systems vary little over the interaction sequence.
Study on simulation methods of atrium building cooling load in hot and humid regions
Energy Technology Data Exchange (ETDEWEB)
Pan, Yiqun; Li, Yuming; Huang, Zhizhong [Institute of Building Performance and Technology, Sino-German College of Applied Sciences, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Wu, Gang [Weldtech Technology (Shanghai) Co. Ltd. (China)
2010-10-15
In recent years, highly glazed atria are popular because of their architectural aesthetics and advantage of introducing daylight into inside. However, cooling load estimation of such atrium buildings is difficult due to complex thermal phenomena that occur in the atrium space. The study aims to find out a simplified method of estimating cooling loads through simulations for various types of atria in hot and humid regions. Atrium buildings are divided into different types. For every type of atrium buildings, both CFD and energy models are developed. A standard method versus the simplified one is proposed to simulate cooling load of atria in EnergyPlus based on different room air temperature patterns as a result from CFD simulation. It incorporates CFD results as input into non-dimensional height room air models in EnergyPlus, and the simulation results are defined as a baseline model in order to compare with the results from the simplified method for every category of atrium buildings. In order to further validate the simplified method an actual atrium office building is tested on site in a typical summer day and measured results are compared with simulation results using the simplified methods. Finally, appropriate methods of simulating different types of atrium buildings are proposed. (author)
DEFF Research Database (Denmark)
Frimurer, Thomas M.; Günther, Peter H.; Sørensen, Morten Dahl
1999-01-01
adiabatic mapping, conformational change, essentialdynamics, free energy simulations, Kunitz type inhibitor *ga3(VI)......adiabatic mapping, conformational change, essentialdynamics, free energy simulations, Kunitz type inhibitor *ga3(VI)...
Multiple time-scale methods in particle simulations of plasmas
International Nuclear Information System (INIS)
Cohen, B.I.
1985-01-01
This paper surveys recent advances in the application of multiple time-scale methods to particle simulation of collective phenomena in plasmas. These methods dramatically improve the efficiency of simulating low-frequency kinetic behavior by allowing the use of a large timestep, while retaining accuracy. The numerical schemes surveyed provide selective damping of unwanted high-frequency waves and preserve numerical stability in a variety of physics models: electrostatic, magneto-inductive, Darwin and fully electromagnetic. The paper reviews hybrid simulation models, the implicitmoment-equation method, the direct implicit method, orbit averaging, and subcycling
The stochastic energy-Casimir method
Arnaudon, Alexis; Ganaba, Nader; Holm, Darryl D.
2018-04-01
In this paper, we extend the energy-Casimir stability method for deterministic Lie-Poisson Hamiltonian systems to provide sufficient conditions for stability in probability of stochastic dynamical systems with symmetries. We illustrate this theory with classical examples of coadjoint motion, including the rigid body, the heavy top, and the compressible Euler equation in two dimensions. The main result is that stable deterministic equilibria remain stable in probability up to a certain stopping time that depends on the amplitude of the noise for finite-dimensional systems and on the amplitude of the spatial derivative of the noise for infinite-dimensional systems. xml:lang="fr"
Advanced Analysis Methods in High Energy Physics
Energy Technology Data Exchange (ETDEWEB)
Pushpalatha C. Bhat
2001-10-03
During the coming decade, high energy physics experiments at the Fermilab Tevatron and around the globe will use very sophisticated equipment to record unprecedented amounts of data in the hope of making major discoveries that may unravel some of Nature's deepest mysteries. The discovery of the Higgs boson and signals of new physics may be around the corner. The use of advanced analysis techniques will be crucial in achieving these goals. The author discusses some of the novel methods of analysis that could prove to be particularly valuable for finding evidence of any new physics, for improving precision measurements and for exploring parameter spaces of theoretical models.
A simulation of laser energy absorption by nanowired surface
Energy Technology Data Exchange (ETDEWEB)
Vasconcelos, Miguel F.S.; Ramos, Alexandre F., E-mail: miguel.vasconcelos@usp.br, E-mail: alex.ramos@usp.br [Universidade de São Paulo (USP), SP (Brazil). Escola de Artes, Ciências e Humanidades
2017-07-01
Despite recent advances on research about laser inertial fusion energy, to increase the portion of energy absorbed by the target's surface from lasers remains as an important challenge. The plasma formed during the initial instants of laser arrival shields the target and prevents the absorption of laser energy by the deeper layers of the material. One strategy to circumvent that effect is the construction of targets whose surfaces are populated with nanowires. The nanowired surfaces have increased absorption of laser energy and constitutes a promising pathway for enhancing laser-matter coupling. In our work we present the results of simulations aiming to investigate how target's geometrical properties might contribute for maximizing laser energy absorption by material. Simulations have been carried out using the software FLASH, a multi-physics platform developed by researchers from the University of Chicago, written in FORTRAN 90 and Python. Different tools for generating target's geometry and analysis of results were developed using Python. Our results show that a nanowired surfaces has an increased energy absorption when compared with non wired surface. The software for visualization developed in this work also allowed an analysis of the spatial dynamics of the target's temperature, electron density, ionization levels and temperature of the radiation emitted by it. (author)
A simulation of laser energy absorption by nanowired surface
International Nuclear Information System (INIS)
Vasconcelos, Miguel F.S.; Ramos, Alexandre F.
2017-01-01
Despite recent advances on research about laser inertial fusion energy, to increase the portion of energy absorbed by the target's surface from lasers remains as an important challenge. The plasma formed during the initial instants of laser arrival shields the target and prevents the absorption of laser energy by the deeper layers of the material. One strategy to circumvent that effect is the construction of targets whose surfaces are populated with nanowires. The nanowired surfaces have increased absorption of laser energy and constitutes a promising pathway for enhancing laser-matter coupling. In our work we present the results of simulations aiming to investigate how target's geometrical properties might contribute for maximizing laser energy absorption by material. Simulations have been carried out using the software FLASH, a multi-physics platform developed by researchers from the University of Chicago, written in FORTRAN 90 and Python. Different tools for generating target's geometry and analysis of results were developed using Python. Our results show that a nanowired surfaces has an increased energy absorption when compared with non wired surface. The software for visualization developed in this work also allowed an analysis of the spatial dynamics of the target's temperature, electron density, ionization levels and temperature of the radiation emitted by it. (author)
Sizing through simulation of systems for photovoltaic solar energy applied to rural electrification
International Nuclear Information System (INIS)
Rodríguez‐Borges, Ciaddy Gina; Sarmiento‐Sera, Antonio
2011-01-01
The present work is based on the sizing method by means of simulation of the photovoltaic systems energy behavior, applied to rural electrification in regions far from the electric net. The denomination of infra/over sized systems is made and a requested analysis of one particular case is exposed, where it is considered two energy options of different qualities of electric service and the economic valuation of each option is requested, with its corresponding argument. The quality level is established with the fault index in the electricity service for energy lack in the batteries, besides the quantity of energy autonomy days of the system. As conclusions, in infra-sizing conditions systems, and with established quality level of service, multiple sizing solutions exist, and under certain conditions, not always the systems with more quality level, are those of more cost, as well as the presence of a minimum cost in the sizing can be obtained by simulation methods. (author)
Energy Technology Data Exchange (ETDEWEB)
Delsante, A.E. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Highett, VIC (Australia). Div. of Building Construction and Engineering
1995-12-31
The Nationwide House Energy Rating Scheme (NatHERS) uses a simulation program as its reference tool to evaluate the energy demand of buildings. The Commonwealth Scientific Industrial Research Organisation (CSIRO) developed software called CHENATH, is a significantly enhanced version of the CHEETAH simulation program. As part of the NatHERS development process, it was considered important to subject CHENATH to further testing. Two separate evaluation projects were undertaken. This paper describes one of these projects. CHENATH was compared with a reference set of eight internationally recognized simulation programs using the BESTEST methodology. Annual heating and cooling energy requirements were compared for a specified set of variations on a simple double-glazed building. Annual incident and transmitted solar radiation was also compared, for which CHENATH agreed very well with the reference set. It also agreed well for heating energy, but tended to over-predict cooling energy. This is largely because it controls an environmental temperature rather than the required air temperature. For the same reason CHENATH over-predicted heating and cooling demands. No major discrepancies were found that would suggest bugs in the program. (author). 4 tabs., 10 figs., 4 refs.
Natural tracer test simulation by stochastic particle tracking method
International Nuclear Information System (INIS)
Ackerer, P.; Mose, R.; Semra, K.
1990-01-01
Stochastic particle tracking methods are well adapted to 3D transport simulations where discretization requirements of other methods usually cannot be satisfied. They do need a very accurate approximation of the velocity field. The described code is based on the mixed hybrid finite element method (MHFEM) to calculated the piezometric and velocity field. The random-walk method is used to simulate mass transport. The main advantages of the MHFEM over FD or FE are the simultaneous calculation of pressure and velocity, which are considered as unknowns; the possibility of interpolating velocities everywhere; and the continuity of the normal component of the velocity vector from one element to another. For these reasons, the MHFEM is well adapted for particle tracking methods. After a general description of the numerical methods, the model is used to simulate the observations made during the Twin Lake Tracer Test in 1983. A good match is found between observed and simulated heads and concentrations. (Author) (12 refs., 4 figs.)
International Nuclear Information System (INIS)
Fuss, M.C.; Munoz, A.; Oller, J.C.; Blanco, F.; Williart, A.; Limao-Vieira, P.; Borge, M.J.G.; Tengblad, O.; Huerga, C.; Tellez, M.; Garcia, G.
2011-01-01
The present study introduces LEPTS, an event-by-event Monte Carlo programme, for simulating an ophthalmic 106 Ru/ 106 Rh applicator relevant in brachytherapy of ocular tumours. The distinctive characteristics of this code are the underlying radiation-matter interaction models that distinguish elastic and several kinds of inelastic collisions, as well as the use of mostly experimental input data. Special emphasis is placed on the treatment of low-energy electrons for generally being responsible for the deposition of a large portion of the total energy imparted to matter. - Highlights: → We present the Monte Carlo code LEPTS, a low-energy particle track simulation. → Carefully selected input data from 10 keV to 1 eV. → Application to an electron emitting Ru-106/Rh-106 plaque used in brachytherapy.
A Finite Element Method for Simulation of Compressible Cavitating Flows
Shams, Ehsan; Yang, Fan; Zhang, Yu; Sahni, Onkar; Shephard, Mark; Oberai, Assad
2016-11-01
This work focuses on a novel approach for finite element simulations of multi-phase flows which involve evolving interface with phase change. Modeling problems, such as cavitation, requires addressing multiple challenges, including compressibility of the vapor phase, interface physics caused by mass, momentum and energy fluxes. We have developed a mathematically consistent and robust computational approach to address these problems. We use stabilized finite element methods on unstructured meshes to solve for the compressible Navier-Stokes equations. Arbitrary Lagrangian-Eulerian formulation is used to handle the interface motions. Our method uses a mesh adaptation strategy to preserve the quality of the volumetric mesh, while the interface mesh moves along with the interface. The interface jump conditions are accurately represented using a discontinuous Galerkin method on the conservation laws. Condensation and evaporation rates at the interface are thermodynamically modeled to determine the interface velocity. We will present initial results on bubble cavitation the behavior of an attached cavitation zone in a separated boundary layer. We acknowledge the support from Army Research Office (ARO) under ARO Grant W911NF-14-1-0301.
Energy Technology Data Exchange (ETDEWEB)
NONE
2001-01-01
In the report, research results discussed in 1999 fiscal year at Nuclear Code Evaluation Committee of Nuclear Code Research Committee were summarized. Present status of Monte Carlo simulation on nuclear energy study was described. Especially, besides of criticality, shielding and core analyses, present status of applications to risk and radiation damage analyses, high energy transport and nuclear theory calculations of Monte Carlo Method was described. The 18 papers are indexed individually. (J.P.N.)
Modelling and simulation of an energy transport phenomenon in a solid-fluid mixture
International Nuclear Information System (INIS)
Costa, M.L.M.; Sampaio, R.; Gama, R.M.S. da.
1989-08-01
In the present work a model for a local description of the energy transfer phenomenon in a binary (solid-fluid) saturated mixture is proposed. The heat transfer in a saturated flow (through a porous medium) between two parallel plates is simulated by using the Finite Volumes Method. (author) [pt
Factorization method for simulating QCD at finite density
International Nuclear Information System (INIS)
Nishimura, Jun
2003-01-01
We propose a new method for simulating QCD at finite density. The method is based on a general factorization property of distribution functions of observables, and it is therefore applicable to any system with a complex action. The so-called overlap problem is completely eliminated by the use of constrained simulations. We test this method in a Random Matrix Theory for finite density QCD, where we are able to reproduce the exact results for the quark number density. (author)
Directory of Open Access Journals (Sweden)
Young Tae Chae
2016-06-01
Full Text Available A calibrated building simulation model was developed to assess the energy performance of a large historic research building. The complexity of space functions and operational conditions with limited availability of energy meters makes it hard to understand the end-used energy consumption in detail and to identify appropriate retrofitting options for reducing energy consumption and greenhouse gas (GHG emissions. An energy simulation model was developed to study the energy usage patterns not only at a building level, but also of the internal thermal zones, and system operations. The model was validated using site measurements of energy usage and a detailed audit of the internal load conditions, system operation, and space programs to minimize the discrepancy between the documented status and actual operational conditions. Based on the results of the calibrated model and end-used energy consumption, the study proposed potential energy conservation measures (ECMs for the building envelope, HVAC system operational methods, and system replacement. It also evaluated each ECM from the perspective of both energy and utility cost saving potentials to help retrofitting plan decision making. The study shows that the energy consumption of the building was highly dominated by the thermal requirements of laboratory spaces. Among other ECMs the demand management option of overriding the setpoint temperature is the most cost effective measure.
Numerical simulations of energy transfer in two collisionless interpenetrating plasmas
Directory of Open Access Journals (Sweden)
Davis S.
2013-11-01
Full Text Available Ion stream instabilities are essential for collisionless shock formation as seen in astrophysics. Weakly relativistic shocks are considered as candidates for sources of high energy cosmic rays. Laboratory experiments may provide a better understanding of this phenomenon. High intensity short pulse laser systems are opening possibilities for efficient ion acceleration to high energies. Their collision with a secondary target could be used for collisionless shock formation. In this paper, using particle-in-cell simulations we are studying interaction of a sub-relativistic, laser created proton beam with a secondary gas target. We show that the ion bunch initiates strong electron heating accompanied by the Weibel-like filamentation and ion energy losses. The energy repartition between ions, electrons and magnetic fields are investigated. This yields insight on the processes occurring in the interstellar medium (ISM and gamma-ray burst afterglows.
Simulation of Solar Energy Use in Livelihood of Buildings
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.
Evaluation of full-scope simulator testing methods
Energy Technology Data Exchange (ETDEWEB)
Feher, M P; Moray, N; Senders, J W; Biron, K [Human Factors North Inc., Toronto, ON (Canada)
1995-03-01
This report discusses the use of full scope nuclear power plant simulators in licensing examinations for Unit First Operators of CANDU reactors. The existing literature is reviewed, and an annotated bibliography of the more important sources provided. Since existing methods are judged inadequate, conceptual bases for designing a system for licensing are discussed, and a method proposed which would make use of objective scoring methods based on data collection in full-scope simulators. A field trial of such a method is described. The practicality of such a method is critically discussed and possible advantages of subjective methods of evaluation considered. (author). 32 refs., 1 tab., 4 figs.
Evaluation of full-scope simulator testing methods
International Nuclear Information System (INIS)
Feher, M.P.; Moray, N.; Senders, J.W.; Biron, K.
1995-03-01
This report discusses the use of full scope nuclear power plant simulators in licensing examinations for Unit First Operators of CANDU reactors. The existing literature is reviewed, and an annotated bibliography of the more important sources provided. Since existing methods are judged inadequate, conceptual bases for designing a system for licensing are discussed, and a method proposed which would make use of objective scoring methods based on data collection in full-scope simulators. A field trial of such a method is described. The practicality of such a method is critically discussed and possible advantages of subjective methods of evaluation considered. (author). 32 refs., 1 tab., 4 figs
Franco, Alejandro A; Bessler, Wolfgang G
2015-01-01
This book reviews the use of innovative physical multiscale modeling methods to deeply understand the electrochemical mechanisms and numerically simulate the structure and properties of electrochemical devices for energy storage and conversion.
Robustness of Component Models in Energy System Simulators
DEFF Research Database (Denmark)
Elmegaard, Brian
2003-01-01
During the development of the component-based energy system simulator DNA (Dynamic Network Analysis), several obstacles to easy use of the program have been observed. Some of these have to do with the nature of the program being based on a modelling language, not a graphical user interface (GUI......). Others have to do with the interaction between models of the nature of the substances in an energy system (e.g., fuels, air, flue gas), models of the components in a system (e.g., heat exchangers, turbines, pumps), and the solver for the system of equations. This paper proposes that the interaction...
New method of fast simulation for a hadron calorimeter response
International Nuclear Information System (INIS)
Kul'chitskij, Yu.; Sutiak, J.; Tokar, S.; Zenis, T.
2003-01-01
In this work we present the new method of a fast Monte-Carlo simulation of a hadron calorimeter response. It is based on the three-dimensional parameterization of the hadronic shower obtained from the ATLAS TILECAL test beam data and GEANT simulations. A new approach of including the longitudinal fluctuations of hadronic shower is described. The obtained results of the fast simulation are in good agreement with the TILECAL experimental data
Simulation of energy- efficient building prototype using different insulating materials
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.
DNA – A General Energy System Simulation Tool
DEFF Research Database (Denmark)
Elmegaard, Brian; Houbak, Niels
2005-01-01
The paper reviews the development of the energy system simulation tool DNA (Dynamic Network Analysis). DNA has been developed since 1989 to be able to handle models of any kind of energy system based on the control volume approach, usually systems of lumped parameter components. DNA has proven...... to be a useful tool in the analysis and optimization of several types of thermal systems: Steam turbines, gas turbines, fuels cells, gasification, refrigeration and heat pumps for both conventional fossil fuels and different types of biomass. DNA is applicable for models of both steady state and dynamic...... operation. The program decides at runtime to apply the DAE solver if the system contains differential equations. This makes it easy to extend an existing steady state model to simulate dynamic operation of the plant. The use of the program is illustrated by examples of gas turbine models. The paper also...
Draught risk index tool for building energy simulations
DEFF Research Database (Denmark)
Vorre, Mette Havgaard; Jensen, Rasmus Lund; Nielsen, Peter V.
2014-01-01
Flow elements combined with a building energy simulation tool can be used to indicate areas and periods when there is a risk of draught in a room. The study tests this concept by making a tool for post-processing of data from building energy simulations. The objective is to show indications...... of draught risk during a whole year, giving building designers a tool for the design stage of a building. The tool uses simple one-at-a-time calculations of flow elements and assesses the uncertainty of the result by counting the number of overlapping flow elements. The calculation time is low, making...... it usable in the early design stage to optimise the building layout. The tool provides an overview of the general draught pattern over a period, e.g. a whole year, and of how often there is a draught risk....
DEFF Research Database (Denmark)
Wang, Weizhi; Wu, Minghao; Palm, Johannes
2018-01-01
for almost linear incident waves. First, we show that the computational fluid dynamics simulations have acceptable agreement to experimental data. We then present a verification and validation study focusing on the solution verification covering spatial and temporal discretization, iterative and domain......The wave loads and the resulting motions of floating wave energy converters are traditionally computed using linear radiation–diffraction methods. Yet for certain cases such as survival conditions, phase control and wave energy converters operating in the resonance region, more complete...... dynamics simulations have largely been overlooked in the wave energy sector. In this article, we apply formal verification and validation techniques to computational fluid dynamics simulations of a passively controlled point absorber. The phase control causes the motion response to be highly nonlinear even...
Analytical simulation of the cantilever-type energy harvester
Directory of Open Access Journals (Sweden)
Jie Mei
2016-01-01
Full Text Available This article describes an analytical model of the cantilever-type energy harvester based on Euler–Bernoulli’s beam theory. Starting from the Hamiltonian form of total energy equation, the bending mode shapes and electromechanical dynamic equations are derived. By solving the constitutive electromechanical dynamic equation, the frequency transfer function of output voltage and power can be obtained. Through a case study of a unimorph piezoelectric energy harvester, this analytical modeling method has been validated by the finite element method.
Daylighting simulation: methods, algorithms, and resources
Energy Technology Data Exchange (ETDEWEB)
Carroll, William L.
1999-12-01
This document presents work conducted as part of Subtask C, ''Daylighting Design Tools'', Subgroup C2, ''New Daylight Algorithms'', of the IEA SHC Task 21 and the ECBCS Program Annex 29 ''Daylight in Buildings''. The search for and collection of daylighting analysis methods and algorithms led to two important observations. First, there is a wide range of needs for different types of methods to produce a complete analysis tool. These include: Geometry; Light modeling; Characterization of the natural illumination resource; Materials and components properties, representations; and Usability issues (interfaces, interoperability, representation of analysis results, etc). Second, very advantageously, there have been rapid advances in many basic methods in these areas, due to other forces. They are in part driven by: The commercial computer graphics community (commerce, entertainment); The lighting industry; Architectural rendering and visualization for projects; and Academia: Course materials, research. This has led to a very rich set of information resources that have direct applicability to the small daylighting analysis community. Furthermore, much of this information is in fact available online. Because much of the information about methods and algorithms is now online, an innovative reporting strategy was used: the core formats are electronic, and used to produce a printed form only secondarily. The electronic forms include both online WWW pages and a downloadable .PDF file with the same appearance and content. Both electronic forms include live primary and indirect links to actual information sources on the WWW. In most cases, little additional commentary is provided regarding the information links or citations that are provided. This in turn allows the report to be very concise. The links are expected speak for themselves. The report consists of only about 10+ pages, with about 100+ primary links, but
Methods of the Water-Energy-Food Nexus
Directory of Open Access Journals (Sweden)
Aiko Endo
2015-10-01
Full Text Available This paper focuses on a collection of methods that can be used to analyze the water-energy-food (WEF nexus. We classify these methods as qualitative or quantitative for interdisciplinary and transdisciplinary research approaches. The methods for interdisciplinary research approaches can be used to unify a collection of related variables, visualize the research problem, evaluate the issue, and simulate the system of interest. Qualitative methods are generally used to describe the nexus in the region of interest, and include primary research methods such as Questionnaire Surveys, as well as secondary research methods such as Ontology Engineering and Integrated Maps. Quantitative methods for examining the nexus include Physical Models, Benefit-Cost Analysis (BCA, Integrated Indices, and Optimization Management Models. The authors discuss each of these methods in the following sections, along with accompanying case studies from research sites in Japan and the Philippines. Although the case studies are specific to two regions, these methods could be applicable to other areas, with appropriate calibration.
Micro energy harvesting from ambient motion : modeling, simulation and design
Energy Technology Data Exchange (ETDEWEB)
Blystad, Lars-Cyril
2012-07-01
Vibration energy harvesting is the process of converting available ambient kinetic energy into useful electrical energy. It can be done on large scale with e.g. a wind-driven turbine. This thesis deals with small scale energy harvesters that are suitable for fabrication in Micro electromechanical Systems (MEMS) technologies. Such MEMS energy harvesters have the potential to supply power for micro power devices. Modeling, simulation and design of MEMS vibration energy harvesters are the foci of this thesis. Transduction mechanisms that are covered are electrostatic and piezoelectric. Electric equivalent circuits are obtained for the use in electromechanical simulations with the circuit simulator SPICE. The feasibility of simulating both narrow- and broadband vibrations, to model different external driving forces, in a standard circuit simulator is demonstrated. Comparisons of the har- vesters performance for different excitations are presented. A selection of passive and active power conditioning circuits is investigated and their performances compared. The active nonlinear switching conversion circuitry performs better than simple passive circuitry, especially when mechanical end stops are in effect. The active switching circuits give higher electromechanical damping, and thus can be driven at higher acceleration amplitudes before end stops are engaged. Mechanical end stops have to be present in all MEMS vibrational energy harvesters. Either due to space limitations, reliability issues, Simliberate introduction of nonlinearities or a combination of these. ulations in the thesis include mechanical end stops and thus include the corresponding nonlinearities introduced in the system. When the mechanical end stops are hit by the proof mass during high-amplitude vibrations, nonlinear effects such as saturation and jumps are present. The end stops increase the effective bandwidth at large acceleration amplitudes. End stops limit the output power for sinusoidal
NMTC/JAM, Simulates High Energy Nuclear Reactions and Nuclear-Meson Transport Processes
International Nuclear Information System (INIS)
Furihata, Shiori
2002-01-01
1 - Description of program or function: NMTC/JAM is an upgraded version of the code system NMTC/JAERI97. NMTC/JAERI97 simulates high energy nuclear reactions and nucleon-meson transport processes. It implements an intra-nuclear cascade model taking account of the in-medium nuclear effects and the pre-equilibrium calculation model based on the exciton one. For treating the nucleon transport process, the nucleon-nucleus cross sections are revised to those derived by the systematics of Pearlstein. Moreover, the level density parameter derived by Ignatyuk is included as a new option for particle evaporation calculation. A geometry package based on the Combinatorial Geometry with multi-array system and the importance sampling technique is implemented in the code. Tally function is also employed for obtaining such physical quantities as neutron energy spectra, heat deposition and nuclide yield without editing a history file. The code can simulate both the primary spallation reaction and the secondary particle transport in the intermediate energy region from 20 MeV to 3.5 GeV by the use of the Monte Carlo technique. The code has been employed in combination with the neutron-photon transport codes available to the energy region below 20 MeV for neutronics calculation of accelerator-based subcritical reactors, analyses of thick target spallation experimented and so on. 2 - Methods: High energy nuclear reactions induced by incident high energy protons, neutrons and pions are simulated with the Monte Carlo Method by the intra-nuclear nucleon-nucleon reaction probabilities based on an intra-nuclear nucleon cascade model followed by the particle evaporation including high energy fission process. Jet-Aa Microscopic transport model (JAM) is employed to simulate high energy nuclear reactions in the energy range of GeV. All reaction channels are taken into account in the JAM calculation. An intra-nuclear cascade model (ISOBAR code) taking account of the in-medium nuclear effects
Monte Carlo simulation of energy deposition by low-energy electrons in molecular hydrogen
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.
Sanitation methods using high energy electron beams
International Nuclear Information System (INIS)
Levaillant, C.; Gallien, C.L.
1979-01-01
Short recycling of waste water and the use of liquid or dehydrated sludge as natural manure for agriculture or animal supplement feed is of great economical and ecological interest. It implies strong biological and chemical disinfection. Ionizing radiations produced by radioactive elements or linear accelerators can be used as a complement of conventional methods in the treatment of liquid and solid waste. An experiment conducted with high-energy electron-beam linear accelerators is presented. Degradation of undesirable metabolites in water occurs for a dose of 50 kRad. Undesirable seeds present in sludge are destroyed with a 200 kRad dose. A 300 kRad dose is sufficient for parasitic and bacterial disinfection (DL 90). Destruction of polio virus (DL 90) is obtained for 400 kRad. Higher doses (1000 to 2000 kRad) produce mineralization of toxic organic mercury, reduce some chemical toxic pollutants present in sludge and improve flocculation. (author)
Method and system of nuclear energy generation
International Nuclear Information System (INIS)
Wilke, W.
1975-01-01
The method is based on the nuclear reaction Li 6 (n,α)H 3 . Thermal neutrons, whose generation require a power reactor, are fed to a lithium deuterite target in such a manner that part of the tritons produced in this reaction undergo nuclear fusion of the kind d(T,n)α with the deuterons of the target. The remaining tritons are reacted with additional deuterons. The tritium produced in this reaction is processed and fed back to the lithium target over a triton source. It is also possible to process the tritium to a target, feed deuterons to it, and in addition to give the neutrons produced from the T(d,n)α reaction after slowing down to thermal energy to the lithium target. (DG/LH) [de
Energy Technology Data Exchange (ETDEWEB)
Ayros, E.; Hildebrandt, H.; Peissner, K. [Fichtner GmbH und Co. KG, Stuttgart (Germany). Wasserbau und Wasserkraftwerke; Bardossy, A. [Stuttgart Univ. (Germany). Inst. fuer Wasserbau
2008-07-01
Simulated Annealing (SA) is an optimization method analogous to the thermodynamic method and is a new alternative for optimising the energy production of hydropower systems with storage capabilities. The SA-Algorithm is presented here and it was applied for the maximization of the energy production of the Baghdara hydropower plant in Afghanistan. The results were also compared with a non-linear optimization method NLP. (orig.)
A particle-based method for granular flow simulation
Chang, Yuanzhang; Bao, Kai; Zhu, Jian; Wu, Enhua
2012-01-01
We present a new particle-based method for granular flow simulation. In the method, a new elastic stress term, which is derived from a modified form of the Hooke's law, is included in the momentum governing equation to handle the friction of granular materials. Viscosity force is also added to simulate the dynamic friction for the purpose of smoothing the velocity field and further maintaining the simulation stability. Benefiting from the Lagrangian nature of the SPH method, large flow deformation can be well handled easily and naturally. In addition, a signed distance field is also employed to enforce the solid boundary condition. The experimental results show that the proposed method is effective and efficient for handling the flow of granular materials, and different kinds of granular behaviors can be well simulated by adjusting just one parameter. © 2012 Science China Press and Springer-Verlag Berlin Heidelberg.
Research on Monte Carlo simulation method of industry CT system
International Nuclear Information System (INIS)
Li Junli; Zeng Zhi; Qui Rui; Wu Zhen; Li Chunyan
2010-01-01
There are a series of radiation physical problems in the design and production of industry CT system (ICTS), including limit quality index analysis; the effect of scattering, efficiency of detectors and crosstalk to the system. Usually the Monte Carlo (MC) Method is applied to resolve these problems. Most of them are of little probability, so direct simulation is very difficult, and existing MC methods and programs can't meet the needs. To resolve these difficulties, particle flux point auto-important sampling (PFPAIS) is given on the basis of auto-important sampling. Then, on the basis of PFPAIS, a particular ICTS simulation method: MCCT is realized. Compared with existing MC methods, MCCT is proved to be able to simulate the ICTS more exactly and effectively. Furthermore, the effects of all kinds of disturbances of ICTS are simulated and analyzed by MCCT. To some extent, MCCT can guide the research of the radiation physical problems in ICTS. (author)
A simple method for potential flow simulation of cascades
Indian Academy of Sciences (India)
vortex panel method to simulate potential flow in cascades is presented. The cascade ... The fluid loading on the blades, such as the normal force and pitching moment, may ... of such discrete infinite array singularities along the blade surface.
A particle-based method for granular flow simulation
Chang, Yuanzhang
2012-03-16
We present a new particle-based method for granular flow simulation. In the method, a new elastic stress term, which is derived from a modified form of the Hooke\\'s law, is included in the momentum governing equation to handle the friction of granular materials. Viscosity force is also added to simulate the dynamic friction for the purpose of smoothing the velocity field and further maintaining the simulation stability. Benefiting from the Lagrangian nature of the SPH method, large flow deformation can be well handled easily and naturally. In addition, a signed distance field is also employed to enforce the solid boundary condition. The experimental results show that the proposed method is effective and efficient for handling the flow of granular materials, and different kinds of granular behaviors can be well simulated by adjusting just one parameter. © 2012 Science China Press and Springer-Verlag Berlin Heidelberg.
Comparing three methods for participatory simulation of hospital work systems
DEFF Research Database (Denmark)
Broberg, Ole; Andersen, Simone Nyholm
Summative Statement: This study compared three participatory simulation methods using different simulation objects: Low resolution table-top setup using Lego figures, full scale mock-ups, and blueprints using Lego figures. It was concluded the three objects by differences in fidelity and affordance...... scenarios using the objects. Results: Full scale mock-ups significantly addressed the local space and technology/tool elements of a work system. In contrast, the table-top simulation object addressed the organizational issues of the future work system. The blueprint based simulation addressed...
Forest canopy BRDF simulation using Monte Carlo method
Huang, J.; Wu, B.; Zeng, Y.; Tian, Y.
2006-01-01
Monte Carlo method is a random statistic method, which has been widely used to simulate the Bidirectional Reflectance Distribution Function (BRDF) of vegetation canopy in the field of visible remote sensing. The random process between photons and forest canopy was designed using Monte Carlo method.
Simulation of scanning geometry for Shadow Shield counter using Monte Carlo method
International Nuclear Information System (INIS)
Deepu, R.; Manohari, M.; Mathiyarasu, R.
2018-01-01
The whole body counting facility at RSD, IGCAR employs a Shadow Shield Counter (SSC) for the assessment of internal exposure of radiation workers from fission and activation products. The SSC system is routinely calibrated using an in-house built Masonite cut sheet phantom, loaded with standard point sources, in scanning mode. The system is capable of measuring gamma energy from 200 keV to 3 MeV. The standard sources available have energies in the range of 300 - 1500 keV. In order to extend the energy range, numerical simulation can be carried out. As, numerical methods cannot simulate scanning mode directly, a novel scheme is attempted to generate the efficiency value for scanning mode through the use of multiple static mode. The same method was also verified through measurement. The efficiency values of the simulation as well two measurements techniques were compared
Simulation methods of nuclear electromagnetic pulse effects in integrated circuits
International Nuclear Information System (INIS)
Cheng Jili; Liu Yuan; En Yunfei; Fang Wenxiao; Wei Aixiang; Yang Yuanzhen
2013-01-01
In the paper the ways to compute the response of transmission line (TL) illuminated by electromagnetic pulse (EMP) were introduced firstly, which include finite-difference time-domain (FDTD) and trans-mission line matrix (TLM); then the feasibility of electromagnetic topology (EMT) in ICs nuclear electromagnetic pulse (NEMP) effect simulation was discussed; in the end, combined with the methods computing the response of TL, a new method of simulate the transmission line in IC illuminated by NEMP was put forward. (authors)
Directory of Open Access Journals (Sweden)
R. Roofegari Nejad
2016-06-01
Full Text Available This paper presents novel methods for Demand Response (DR programs by considering welfare state of consumers, to deal with the operational uncertainties, such as wind energy and energy price, within the framework of a smart microgrid. In this regard, total loads of microgrid are classified into two groups and each one is represented by a typical load. First group is energy storage capability represents by heater loads and second is curtailment capability loads represents by lighting loads. Next by the proposed DR methods, consumed energy of the all loads is coupled to the wind energy rate and energy price. Finally these methods are applied in the operation of a smart microgrid, consists of dispatchable supplier (microturbine, nondispatchable supplier (wind turbine, energy storage system and loads with the capability of energy exchanging with upstream distribution network. In order to consider uncertainties, Monte Carlo simulation method is used, which various scenarios are generated and applied in the operation of microgrid. In the end, the simulation results on a typical microgrid show that implementing proposed DR methods contributes to increasing total operational profit of smart microgrid and also decreasing the risk of low profit too.
An introduction to computer simulation methods applications to physical systems
Gould, Harvey; Christian, Wolfgang
2007-01-01
Now in its third edition, this book teaches physical concepts using computer simulations. The text incorporates object-oriented programming techniques and encourages readers to develop good programming habits in the context of doing physics. Designed for readers at all levels , An Introduction to Computer Simulation Methods uses Java, currently the most popular programming language. Introduction, Tools for Doing Simulations, Simulating Particle Motion, Oscillatory Systems, Few-Body Problems: The Motion of the Planets, The Chaotic Motion of Dynamical Systems, Random Processes, The Dynamics of Many Particle Systems, Normal Modes and Waves, Electrodynamics, Numerical and Monte Carlo Methods, Percolation, Fractals and Kinetic Growth Models, Complex Systems, Monte Carlo Simulations of Thermal Systems, Quantum Systems, Visualization and Rigid Body Dynamics, Seeing in Special and General Relativity, Epilogue: The Unity of Physics For all readers interested in developing programming habits in the context of doing phy...
Motion simulation of hydraulic driven safety rod using FSI method
International Nuclear Information System (INIS)
Jung, Jaeho; Kim, Sanghaun; Yoo, Yeonsik; Cho, Yeonggarp; Kim, Jong In
2013-01-01
Hydraulic driven safety rod which is one of them is being developed by Division for Reactor Mechanical Engineering, KAERI. In this paper the motion of this rod is simulated by fluid structure interaction (FSI) method before manufacturing for design verification and pump sizing. A newly designed hydraulic driven safety rod which is one of reactivity control mechanism is simulated using FSI method for design verification and pump sizing. The simulation is done in CFD domain with UDF. The pressure drop is changed slightly by flow rates. It means that the pressure drop is mainly determined by weight of moving part. The simulated velocity of piston is linearly proportional to flow rates so the pump can be sized easily according to the rising and drop time requirement of the safety rod using the simulation results
Bagli, Enrico; Guidi, Vincenzo
2013-08-01
A toolkit for the simulation of coherent interactions between high-energy charged particles and complex crystal structures, called DYNECHARM++ has been developed. The code has been written in C++ language taking advantage of this object-oriented programing method. The code is capable to evaluating the electrical characteristics of complex atomic structures and to simulate and track the particle trajectory within them. Calculation method of electrical characteristics based on their expansion in Fourier series has been adopted. Two different approaches to simulate the interaction have been adopted, relying on the full integration of particle trajectories under the continuum potential approximation and on the definition of cross-sections of coherent processes. Finally, the code has proved to reproduce experimental results and to simulate interaction of charged particles with complex structures.
LDRD Final Report: Adaptive Methods for Laser Plasma Simulation
International Nuclear Information System (INIS)
Dorr, M R; Garaizar, F X; Hittinger, J A
2003-01-01
The goal of this project was to investigate the utility of parallel adaptive mesh refinement (AMR) in the simulation of laser plasma interaction (LPI). The scope of work included the development of new numerical methods and parallel implementation strategies. The primary deliverables were (1) parallel adaptive algorithms to solve a system of equations combining plasma fluid and light propagation models, (2) a research code implementing these algorithms, and (3) an analysis of the performance of parallel AMR on LPI problems. The project accomplished these objectives. New algorithms were developed for the solution of a system of equations describing LPI. These algorithms were implemented in a new research code named ALPS (Adaptive Laser Plasma Simulator) that was used to test the effectiveness of the AMR algorithms on the Laboratory's large-scale computer platforms. The details of the algorithm and the results of the numerical tests were documented in an article published in the Journal of Computational Physics [2]. A principal conclusion of this investigation is that AMR is most effective for LPI systems that are ''hydrodynamically large'', i.e., problems requiring the simulation of a large plasma volume relative to the volume occupied by the laser light. Since the plasma-only regions require less resolution than the laser light, AMR enables the use of efficient meshes for such problems. In contrast, AMR is less effective for, say, a single highly filamented beam propagating through a phase plate, since the resulting speckle pattern may be too dense to adequately separate scales with a locally refined mesh. Ultimately, the gain to be expected from the use of AMR is highly problem-dependent. One class of problems investigated in this project involved a pair of laser beams crossing in a plasma flow. Under certain conditions, energy can be transferred from one beam to the other via a resonant interaction with an ion acoustic wave in the crossing region. AMR provides an
M.A.E.G.U.S.: Measuring alternate energy generation via unity simulation
Nataraja, Kavin Muhilan
This paper presents the MAEGUS serious game and a study to determine its efficacy as a pedagogical tool. The MAEGUS serious game teaches sustainable energy concepts through gameplay simulating wind turbines and solar arrays. Players take the role of an energy manager for a city and use realistic data and information visualizations to learn the physical factors of wind and solar energy generation. The MAEGUS serious game study compares game assisted learning to a more traditional teaching method such as reading material in a crossover study, the results of which can inform future serious game development for educational purposes.
WINS. Market Simulation Tool for Facilitating Wind Energy Integration
Energy Technology Data Exchange (ETDEWEB)
Shahidehpour, Mohammad [Illinois Inst. of Technology, Chicago, IL (United States)
2012-10-30
Integrating 20% or more wind energy into the system and transmitting large sums of wind energy over long distances will require a decision making capability that can handle very large scale power systems with tens of thousands of buses and lines. There is a need to explore innovative analytical and implementation solutions for continuing reliable operations with the most economical integration of additional wind energy in power systems. A number of wind integration solution paths involve the adoption of new operating policies, dynamic scheduling of wind power across interties, pooling integration services, and adopting new transmission scheduling practices. Such practices can be examined by the decision tool developed by this project. This project developed a very efficient decision tool called Wind INtegration Simulator (WINS) and applied WINS to facilitate wind energy integration studies. WINS focused on augmenting the existing power utility capabilities to support collaborative planning, analysis, and wind integration project implementations. WINS also had the capability of simulating energy storage facilities so that feasibility studies of integrated wind energy system applications can be performed for systems with high wind energy penetrations. The development of WINS represents a major expansion of a very efficient decision tool called POwer Market Simulator (POMS), which was developed by IIT and has been used extensively for power system studies for decades. Specifically, WINS provides the following superiorities; (1) An integrated framework is included in WINS for the comprehensive modeling of DC transmission configurations, including mono-pole, bi-pole, tri-pole, back-to-back, and multi-terminal connection, as well as AC/DC converter models including current source converters (CSC) and voltage source converters (VSC); (2) An existing shortcoming of traditional decision tools for wind integration is the limited availability of user interface, i.e., decision
A SOFTWARE TOOL TO COMPARE MEASURED AND SIMULATED BUILDING ENERGY PERFORMANCE DATA
Energy Technology Data Exchange (ETDEWEB)
Maile, Tobias; Bazjanac, Vladimir; O' Donnell, James; Garr, Matthew
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 and 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.
Energy Technology Data Exchange (ETDEWEB)
Potter, Kristin C [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Brunhart-Lupo, Nicholas J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Bush, Brian W [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Gruchalla, Kenny M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Bugbee, Bruce [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Krishnan, Venkat K [National Renewable Energy Laboratory (NREL), Golden, CO (United States)
2017-10-09
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 sound 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.
Thermal dynamic simulation of wall for building energy efficiency under varied climate environment
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.
Real time simulation method for fast breeder reactors dynamics
International Nuclear Information System (INIS)
Miki, Tetsushi; Mineo, Yoshiyuki; Ogino, Takamichi; Kishida, Koji; Furuichi, Kenji.
1985-01-01
The development of multi-purpose real time simulator models with suitable plant dynamics was made; these models can be used not only in training operators but also in designing control systems, operation sequences and many other items which must be studied for the development of new type reactors. The prototype fast breeder reactor ''Monju'' is taken as an example. Analysis is made on various factors affecting the accuracy and computer load of its dynamic simulation. A method is presented which determines the optimum number of nodes in distributed systems and time steps. The oscillations due to the numerical instability are observed in the dynamic simulation of evaporators with a small number of nodes, and a method to cancel these oscillations is proposed. It has been verified through the development of plant dynamics simulation codes that these methods can provide efficient real time dynamics models of fast breeder reactors. (author)
Simulation of plume dynamics by the Lattice Boltzmann Method
Mora, Peter; Yuen, David A.
2017-09-01
The Lattice Boltzmann Method (LBM) is a semi-microscopic method to simulate fluid mechanics by modelling distributions of particles moving and colliding on a lattice. We present 2-D simulations using the LBM of a fluid in a rectangular box being heated from below, and cooled from above, with a Rayleigh of Ra = 108, similar to current estimates of the Earth's mantle, and a Prandtl number of 5000. At this Prandtl number, the flow is found to be in the non-inertial regime where the inertial terms denoted I ≪ 1. Hence, the simulations presented lie within the regime of relevance for geodynamical problems. We obtain narrow upwelling plumes with mushroom heads and chutes of downwelling fluid as expected of a flow in the non-inertial regime. The method developed demonstrates that the LBM has great potential for simulating thermal convection and plume dynamics relevant to geodynamics, albeit with some limitations.
Method of simulating dose reduction for digital radiographic systems
International Nuclear Information System (INIS)
Baath, M.; Haakansson, M.; Tingberg, A.; Maansson, L. G.
2005-01-01
The optimisation of image quality vs. radiation dose is an important task in medical imaging. To obtain maximum validity of the optimisation, it must be based on clinical images. Images at different dose levels can then either be obtained by collecting patient images at the different dose levels sought to investigate - including additional exposures and permission from an ethical committee - or by manipulating images to simulate different dose levels. The aim of the present work was to develop a method of simulating dose reduction for digital radiographic systems. The method uses information about the detective quantum efficiency and noise power spectrum at the original and simulated dose levels to create an image containing filtered noise. When added to the original image this results in an image with noise which, in terms of frequency content, agrees with the noise present in an image collected at the simulated dose level. To increase the validity, the method takes local dose variations in the original image into account. The method was tested on a computed radiography system and was shown to produce images with noise behaviour similar to that of images actually collected at the simulated dose levels. The method can, therefore, be used to modify an image collected at one dose level so that it simulates an image of the same object collected at any lower dose level. (authors)
A tool for simulating parallel branch-and-bound methods
Golubeva, Yana; Orlov, Yury; Posypkin, Mikhail
2016-01-01
The Branch-and-Bound method is known as one of the most powerful but very resource consuming global optimization methods. Parallel and distributed computing can efficiently cope with this issue. The major difficulty in parallel B&B method is the need for dynamic load redistribution. Therefore design and study of load balancing algorithms is a separate and very important research topic. This paper presents a tool for simulating parallel Branchand-Bound method. The simulator allows one to run load balancing algorithms with various numbers of processors, sizes of the search tree, the characteristics of the supercomputer's interconnect thereby fostering deep study of load distribution strategies. The process of resolution of the optimization problem by B&B method is replaced by a stochastic branching process. Data exchanges are modeled using the concept of logical time. The user friendly graphical interface to the simulator provides efficient visualization and convenient performance analysis.
A tool for simulating parallel branch-and-bound methods
Directory of Open Access Journals (Sweden)
Golubeva Yana
2016-01-01
Full Text Available The Branch-and-Bound method is known as one of the most powerful but very resource consuming global optimization methods. Parallel and distributed computing can efficiently cope with this issue. The major difficulty in parallel B&B method is the need for dynamic load redistribution. Therefore design and study of load balancing algorithms is a separate and very important research topic. This paper presents a tool for simulating parallel Branchand-Bound method. The simulator allows one to run load balancing algorithms with various numbers of processors, sizes of the search tree, the characteristics of the supercomputer’s interconnect thereby fostering deep study of load distribution strategies. The process of resolution of the optimization problem by B&B method is replaced by a stochastic branching process. Data exchanges are modeled using the concept of logical time. The user friendly graphical interface to the simulator provides efficient visualization and convenient performance analysis.
A new rapid method for rockfall energies and distances estimation
Giacomini, Anna; Ferrari, Federica; Thoeni, Klaus; Lambert, Cedric
2016-04-01
Rockfalls are characterized by long travel distances and significant energies. Over the last decades, three main methods have been proposed in the literature to assess the rockfall runout: empirical, process-based and GIS-based methods (Dorren, 2003). Process-based methods take into account the physics of rockfall by simulating the motion of a falling rock along a slope and they are generally based on a probabilistic rockfall modelling approach that allows for taking into account the uncertainties associated with the rockfall phenomenon. Their application has the advantage of evaluating the energies, bounce heights and distances along the path of a falling block, hence providing valuable information for the design of mitigation measures (Agliardi et al., 2009), however, the implementation of rockfall simulations can be time-consuming and data-demanding. This work focuses on the development of a new methodology for estimating the expected kinetic energies and distances of the first impact at the base of a rock cliff, subject to the conditions that the geometry of the cliff and the properties of the representative block are known. The method is based on an extensive two-dimensional sensitivity analysis, conducted by means of kinematic simulations based on probabilistic modelling of two-dimensional rockfall trajectories (Ferrari et al., 2016). To take into account for the uncertainty associated with the estimation of the input parameters, the study was based on 78400 rockfall scenarios performed by systematically varying the input parameters that are likely to affect the block trajectory, its energy and distance at the base of the rock wall. The variation of the geometry of the rock cliff (in terms of height and slope angle), the roughness of the rock surface and the properties of the outcropping material were considered. A simplified and idealized rock wall geometry was adopted. The analysis of the results allowed finding empirical laws that relate impact energies
Analysis of Monte Carlo methods for the simulation of photon transport
International Nuclear Information System (INIS)
Carlsson, G.A.; Kusoffsky, L.
1975-01-01
In connection with the transport of low-energy photons (30 - 140 keV) through layers of water of different thicknesses, various aspects of Monte Carlo methods are examined in order to improve their effectivity (to produce statistically more reliable results with shorter computer times) and to bridge the gap between more physical methods and more mathematical ones. The calculations are compared with results of experiments involving the simulation of photon transport, using direct methods and collision density ones (J.S.)
Improved methods to evaluate realised energy savings
Boonekamp, P.G.M.
2005-01-01
This thesis regards the calculation of realised energy savings at national and sectoral level, and the policy contribution to total savings. It is observed that the results of monitoring and evaluation studies on realised energy savings are hardly applied in energy saving policy. Causes are the lack
SIMULATIONS OF THE AGS MMPS STORING ENERGY IN CAPACITOR BANKS
Energy Technology Data Exchange (ETDEWEB)
MARNERIS,I.; BADEA, V.S.; BONATI, R.; ROSER, T.; SANDBERG, J.
2007-06-25
The Brookhaven AGS Main Magnet Power Supply (MMPS) is a thyristor control supply rated at 5500 Amps, +/-9000 Volts. The peak magnet power is 50 MWatts. The power supply is fed from a motor/generator manufactured by Siemens. The generator is 3 phase 7500 Volts rated at 50 MVA. The peak power requirements come from the stored energy in the rotor of the motor/generator. The motor generator is about 45 years old, made by Siemens and it is not clear if companies will be manufacturing similar machines in the future. We are therefore investigating different ways of storing energy for future AGS MMPS operations. This paper will present simulations of a power supply where energy is stored in capacitor banks. Two dc to dc converters will be presented along with the control system of the power section. The switching elements will be IGCT's made by ABB. The simulation program used is called PSIM version 6.1. The average power from the local power authority into the power supply will be kept constant during the pulsing of the magnets at +/-50 MW. The reactive power will also be kept constant below 1.5 MVAR. Waveforms will be presented.
SIMULATIONS OF THE AGS MMPS STORING ENERGY IN CAPACITOR BANKS
International Nuclear Information System (INIS)
MARNERIS, I.; BADEA, V.S.; BONATI, R.; ROSER, T.; SANDBERG, J.
2007-01-01
The Brookhaven AGS Main Magnet Power Supply (MMPS) is a thyristor control supply rated at 5500 Amps, +/-9000 Volts. The peak magnet power is 50 MWatts. The power supply is fed from a motor/generator manufactured by Siemens. The generator is 3 phase 7500 Volts rated at 50 MVA. The peak power requirements come from the stored energy in the rotor of the motor/generator. The motor generator is about 45 years old, made by Siemens and it is not clear if companies will be manufacturing similar machines in the future. We are therefore investigating different ways of storing energy for future AGS MMPS operations. This paper will present simulations of a power supply where energy is stored in capacitor banks. Two dc to dc converters will be presented along with the control system of the power section. The switching elements will be IGCT's made by ABB. The simulation program used is called PSIM version 6.1. The average power from the local power authority into the power supply will be kept constant during the pulsing of the magnets at +/-50 MW. The reactive power will also be kept constant below 1.5 MVAR. Waveforms will be presented
The Simulation and Analysis of the Closed Die Hot Forging Process by A Computer Simulation Method
Directory of Open Access Journals (Sweden)
Dipakkumar Gohil
2012-06-01
Full Text Available The objective of this research work is to study the variation of various parameters such as stress, strain, temperature, force, etc. during the closed die hot forging process. A computer simulation modeling approach has been adopted to transform the theoretical aspects in to a computer algorithm which would be used to simulate and analyze the closed die hot forging process. For the purpose of process study, the entire deformation process has been divided in to finite number of steps appropriately and then the output values have been computed at each deformation step. The results of simulation have been graphically represented and suitable corrective measures are also recommended, if the simulation results do not agree with the theoretical values. This computer simulation approach would significantly improve the productivity and reduce the energy consumption of the overall process for the components which are manufactured by the closed die forging process and contribute towards the efforts in reducing the global warming.
A review of methods for the evaluation of the energy contribution of daylight in buildings
Energy Technology Data Exchange (ETDEWEB)
Attenborough, M; Goodwin, A
1996-07-01
A review has been undertaken of energy prediction methods and daylight calculation methods currently in use in the UK. This was based on a literature review and discussions with large engineering practices and academics involved in the areas of daylighting and energy simulation research. The aim of this review was to identify manual methods or computer programs that are capable of determining energy use in non-domestic buildings and of taking into account the energy savings resulting from daylighting. One potential application for these methods is in supporting anticipated energy targets for non-domestic buildings within Building Regulations and other energy labelling schemes. The review has identified a range of methods which are capable of predicting overall energy use while accounting for daylight. These vary in complexity from empirical methods such as ESICHECK and the CIBSE Energy Code through to dynamic energy simulation models such as DOE 2 and ESP. For each of the methods identified a brief assessment has been made of their technical capabilities ease of use and availability. These assessments have been based on discussions with users and program developers. Descriptions of the various methods are given. (Author)
Simulation of a low energy beam transport line
International Nuclear Information System (INIS)
Yang Yao; Liu Zhanwen; Zhang Wenhui; Ma Hongyi; Zhang Xuezhen; Zhao Hongwei; Yao Ze'en
2012-01-01
A 2.45 GHz electron cyclotron resonance intense proton source and a low energy beam transport line with dual-Glaser lens were designed and fabricated by Institute of Modern Physics for a compact pulsed hadron source at Tsinghua. The intense proton beams extracted from the ion source are transported through the transport line to match the downstream radio frequency quadrupole accelerator. Particle-in-cell code BEAMPATH was used to carry out the beam transport simulations and optimize the magnetic field structures of the transport line. Emittance growth due to space charge and spherical aberrations of the Glaser lens were studied in both theory and simulation. The results show that narrow beam has smaller aberrations and better beam quality through the transport line. To better match the radio frequency quadrupole accelerator, a shorter transport line is desired with sufficient space charge neutralization. (authors)
Boll, Torben; Zhu, Zhiyong; Al-Kassab, Talaat; Schwingenschlö gl, Udo
2012-01-01
In this article the Cu-Au binding energy in Cu3Au is determined by comparing experimental atom probe tomography (APT) results to simulations. The resulting bonding energy is supported by density functional theory calculations. The APT simulations
International Nuclear Information System (INIS)
Visbal, Jorge H. Wilches; Costa, Alessandro M.
2016-01-01
Percentage depth dose of electron beams represents an important item of data in radiation therapy treatment since it describes the dosimetric properties of these. Using an accurate transport theory, or the Monte Carlo method, has been shown obvious differences between the dose distribution of electron beams of a clinical accelerator in a water simulator object and the dose distribution of monoenergetic electrons of nominal energy of the clinical accelerator in water. In radiotherapy, the electron spectra should be considered to improve the accuracy of dose calculation since the shape of PDP curve depends of way how radiation particles deposit their energy in patient/phantom, that is, the spectrum. Exist three principal approaches to obtain electron energy spectra from central PDP: Monte Carlo Method, Direct Measurement and Inverse Reconstruction. In this work it will be presented the Simulated Annealing method as a practical, reliable and simple approach of inverse reconstruction as being an optimal alternative to other options. (author)
Two methods for decreasing the flexibility gap in national energy systems
International Nuclear Information System (INIS)
Batas Bjelić, Ilija; Rajaković, Nikola; Krajačić, Goran; Duić, Neven
2016-01-01
More variable renewable energy sources and energy efficiency measures create an additional flexibility gap and require a novel energy planning method for sustainable national energy systems. The firstly presented method uses only EnergyPLAN tool in order to decrease the flexibility gap in a national energy system. Generic Optimization program (GenOpt"®) is an optimization program for the minimization of a cost function that is evaluated by an external simulation program, such as EnergyPLAN, which was used as the second method in this research. Successful strategies to decrease the flexibility gap are verified on the case of the Serbian national energy system using two methods for its structure design: (1) the iterative method, based on heuristics and manual procedure of using only EnergyPLAN, and (2) the optimization method, based on soft-linking of EnergyPLAN with GenOpt"®. The latter method, named EPOPT (EnergyPlan-genOPT), found the solution for the structure of the sustainable national energy system at the total cost of 8190 M€, while the iterative method was only able to find solutions at the cost in the range of 8251–8598 M€ by targeting only one sustainability goal. The advantages of the EPOPT method are its accuracy, user-friendliness and minimal costs, are valuable for planners. - Highlights: • Heuristic and optimization method for sustainable national energy system structure. • The same input assumptions resulting in different energy system structure. • Both methods are successful in decreasing of the flexibility gap. • The EPOPT method advantages are in the speed, accuracy and planner comfort. • Advanced method for the sustainable national energy policy planning.
Plasma simulations using the Car-Parrinello method
International Nuclear Information System (INIS)
Clerouin, J.; Zerah, G.; Benisti, D.; Hansen, J.P.
1990-01-01
A simplified version of the Car-Parrinello method, based on the Thomas-Fermi (local density) functional for the electrons, is adapted to the simulation of the ionic dynamics in dense plasmas. The method is illustrated by an explicit application to a degenerate one-dimensional hydrogen plasma
Nonequilibrium relaxation method – An alternative simulation strategy
Indian Academy of Sciences (India)
One well-established simulation strategy to study the thermal phases and transitions of a given microscopic model system is the so-called equilibrium method, in which one first realizes the equilibrium ensemble of a finite system and then extrapolates the results to infinite system. This equilibrium method traces over the ...
A direct simulation method for flows with suspended paramagnetic particles
Kang, T.G.; Hulsen, M.A.; Toonder, den J.M.J.; Anderson, P.D.; Meijer, H.E.H.
2008-01-01
A direct numerical simulation method based on the Maxwell stress tensor and a fictitious domain method has been developed to solve flows with suspended paramagnetic particles. The numerical scheme enables us to take into account both hydrodynamic and magnetic interactions between particles in a
DRK methods for time-domain oscillator simulation
Sevat, M.F.; Houben, S.H.M.J.; Maten, ter E.J.W.; Di Bucchianico, A.; Mattheij, R.M.M.; Peletier, M.A.
2006-01-01
This paper presents a new Runge-Kutta type integration method that is well-suited for time-domain simulation of oscillators. A unique property of the new method is that its damping characteristics can be controlled by a continuous parameter.
The afforestation problem: a heuristic method based on simulated annealing
DEFF Research Database (Denmark)
Vidal, Rene Victor Valqui
1992-01-01
This paper presents the afforestation problem, that is the location and design of new forest compartments to be planted in a given area. This optimization problem is solved by a two-step heuristic method based on simulated annealing. Tests and experiences with this method are also presented....
Multilevel panel method for wind turbine rotor flow simulations
van Garrel, Arne
2016-01-01
Simulation methods of wind turbine aerodynamics currently in use mainly fall into two categories: the first is the group of traditional low-fidelity engineering models and the second is the group of computationally expensive CFD methods based on the Navier-Stokes equations. For an engineering
LOMEGA: a low frequency, field implicit method for plasma simulation
International Nuclear Information System (INIS)
Barnes, D.C.; Kamimura, T.
1982-04-01
Field implicit methods for low frequency plasma simulation by the LOMEGA (Low OMEGA) codes are described. These implicit field methods may be combined with particle pushing algorithms using either Lorentz force or guiding center force models to study two-dimensional, magnetized, electrostatic plasmas. Numerical results for ωsub(e)deltat>>1 are described. (author)
Performance evaluation of sea surface simulation methods for target detection
Xia, Renjie; Wu, Xin; Yang, Chen; Han, Yiping; Zhang, Jianqi
2017-11-01
With the fast development of sea surface target detection by optoelectronic sensors, machine learning has been adopted to improve the detection performance. Many features can be learned from training images by machines automatically. However, field images of sea surface target are not sufficient as training data. 3D scene simulation is a promising method to address this problem. For ocean scene simulation, sea surface height field generation is the key point to achieve high fidelity. In this paper, two spectra-based height field generation methods are evaluated. Comparison between the linear superposition and linear filter method is made quantitatively with a statistical model. 3D ocean scene simulating results show the different features between the methods, which can give reference for synthesizing sea surface target images with different ocean conditions.
Clinical simulation as an evaluation method in health informatics
DEFF Research Database (Denmark)
Jensen, Sanne
2016-01-01
Safe work processes and information systems are vital in health care. Methods for design of health IT focusing on patient safety are one of many initiatives trying to prevent adverse events. Possible patient safety hazards need to be investigated before health IT is integrated with local clinical...... work practice including other technology and organizational structure. Clinical simulation is ideal for proactive evaluation of new technology for clinical work practice. Clinical simulations involve real end-users as they simulate the use of technology in realistic environments performing realistic...... tasks. Clinical simulation study assesses effects on clinical workflow and enables identification and evaluation of patient safety hazards before implementation at a hospital. Clinical simulation also offers an opportunity to create a space in which healthcare professionals working in different...
Scalable Methods for Eulerian-Lagrangian Simulation Applied to Compressible Multiphase Flows
Zwick, David; Hackl, Jason; Balachandar, S.
2017-11-01
Multiphase flows can be found in countless areas of physics and engineering. Many of these flows can be classified as dispersed two-phase flows, meaning that there are solid particles dispersed in a continuous fluid phase. A common technique for simulating such flow is the Eulerian-Lagrangian method. While useful, this method can suffer from scaling issues on larger problem sizes that are typical of many realistic geometries. Here we present scalable techniques for Eulerian-Lagrangian simulations and apply it to the simulation of a particle bed subjected to expansion waves in a shock tube. The results show that the methods presented here are viable for simulation of larger problems on modern supercomputers. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1315138. This work was supported in part by the U.S. Department of Energy under Contract No. DE-NA0002378.
On theory and simulation of heaving-buoy wave-energy converters with control
Energy Technology Data Exchange (ETDEWEB)
Eidsmoen, H.
1995-12-01
Heaving-buoy wave-energy converters with control were studied. The buoy is small compared to the wavelength. The resonance bandwidth is then narrow and the energy conversion in irregular waves can be significantly increased if the oscillatory motion of the device can be actively controlled, and the power output from the converter will vary less with time than the wave power transport. A system of two concentric cylinders of the same radius, oscillating in heave only, is analysed in the frequency-domain. The mathematical model can be used to study a tight-moored buoy, as well as a buoy reacting against a submerged body. The knowledge of the frequency-domain hydrodynamic parameters is used to develop frequency-domain and time-domain mathematical models of heaving-buoy wave energy converters. The main emphasis is on using control to maximize the energy production and to protect the machinery of the wave-energy converter in very large waves. Three different methods are used to study control. (1) In the frequency-domain explicit analytical expressions for the optimum oscillation are found, assuming a continuous sinusoidal control force, and from these expressions the optimum time-domain oscillation can be determined. (2) The second method uses optimal control theory, using a control variable as the instrument for the optimisation. Unlike the first method, this method can include non-linearities. But this method gives numerical time series for the state variables and the control variable rather than analytical expressions for the optimum oscillation. (3) The third method is time-domain simulation. Non-linear forces are included, but the method only gives the response of the system to a given incident wave. How the different methods can be used to develop real-time control is discussed. Simulations are performed for a tight-moored heaving-buoy converter with a high-pressure hydraulic system for energy production and motion control. 147 refs., 38 figs., 22 tabs.
Application of direct simulation Monte Carlo method for analysis of AVLIS evaporation process
International Nuclear Information System (INIS)
Nishimura, Akihiko
1995-01-01
The computation code of the direct simulation Monte Carlo (DSMC) method was developed in order to analyze the atomic vapor evaporation in atomic vapor laser isotope separation (AVLIS). The atomic excitation temperatures of gadolinium atom were calculated for the model with five low lying states. Calculation results were compared with the experiments obtained by laser absorption spectroscopy. Two types of DSMC simulations which were different in inelastic collision procedure were carried out. It was concluded that the energy transfer was forbidden unless the total energy of the colliding atoms exceeds a threshold value. (author)
Energy Technology Data Exchange (ETDEWEB)
Kurnik, Charles W. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Keates, Steven [ADM Associates, Inc., Atlanta, GA (United States)
2017-10-09
This protocol is intended to describe the recommended method when evaluating the whole-building performance of new construction projects in the commercial sector. The protocol focuses on energy conservation measures (ECMs) or packages of measures where evaluators can analyze impacts using building simulation. These ECMs typically require the use of calibrated building simulations under Option D of the International Performance Measurement and Verification Protocol (IPMVP).
Architecture oriented modeling and simulation method for combat mission profile
Directory of Open Access Journals (Sweden)
CHEN Xia
2017-05-01
Full Text Available In order to effectively analyze the system behavior and system performance of combat mission profile, an architecture-oriented modeling and simulation method is proposed. Starting from the architecture modeling,this paper describes the mission profile based on the definition from National Military Standard of China and the US Department of Defense Architecture Framework(DoDAFmodel, and constructs the architecture model of the mission profile. Then the transformation relationship between the architecture model and the agent simulation model is proposed to form the mission profile executable model. At last,taking the air-defense mission profile as an example,the agent simulation model is established based on the architecture model,and the input and output relations of the simulation model are analyzed. It provides method guidance for the combat mission profile design.
A nondissipative simulation method for the drift kinetic equation
International Nuclear Information System (INIS)
Watanabe, Tomo-Hiko; Sugama, Hideo; Sato, Tetsuya
2001-07-01
With the aim to study the ion temperature gradient (ITG) driven turbulence, a nondissipative kinetic simulation scheme is developed and comprehensively benchmarked. The new simulation method preserving the time-reversibility of basic kinetic equations can successfully reproduce the analytical solutions of asymmetric three-mode ITG equations which are extended to provide a more general reference for benchmarking than the previous work [T.-H. Watanabe, H. Sugama, and T. Sato: Phys. Plasmas 7 (2000) 984]. It is also applied to a dissipative three-mode system, and shows a good agreement with the analytical solution. The nondissipative simulation result of the ITG turbulence accurately satisfies the entropy balance equation. Usefulness of the nondissipative method for the drift kinetic simulations is confirmed in comparisons with other dissipative schemes. (author)
DEFF Research Database (Denmark)
Petersen, Steffen; Svendsen, Svend
2011-01-01
A method for simulating predictive control of building systems operation in the early stages of building design is presented. The method uses building simulation based on weather forecasts to predict whether there is a future heating or cooling requirement. This information enables the thermal...... control systems of the building to respond proactively to keep the operational temperature within the thermal comfort range with the minimum use of energy. The method is implemented in an existing building simulation tool designed to inform decisions in the early stages of building design through...... parametric analysis. This enables building designers to predict the performance of the method and include it as a part of the solution space. The method furthermore facilitates the task of configuring appropriate building systems control schemes in the tool, and it eliminates time consuming manual...
Macroscopic/microscopic simulation of nuclear reactions at intermediate energies
International Nuclear Information System (INIS)
Lacroix, D.; Van Lauwe, A.; Durand, D.
2003-01-01
An event generator, HIPSE (Heavy-Ion Phase-Space Exploration), dedicated to the description of nuclear collisions in the intermediate energy range is presented. The model simulates events for reactions close to the fusion barrier (5-10 MeV/A) up to higher energy (100 MeV/A) and it gives access to the phase-space explored during the collision. The development of HIPSE has been largely influenced by experimental observations. We have separated the reaction into 4 steps: contact, fragment formation, chemical freeze-out, and in-flight deexcitation. HIPSE will be useful for a study of various mechanisms such as neck fragmentation or multi-fragmentation
Energy Technology Data Exchange (ETDEWEB)
Ortiz-Ramírez, Pablo, E-mail: rapeitor@ug.uchile.cl; Ruiz, Andrés [Departamento de Física, Facultad de Ciencias, Universidad de Chile (Chile)
2016-07-07
The Monte Carlo simulation of the gamma spectroscopy systems is a common practice in these days. The most popular softwares to do this are MCNP and Geant4 codes. The intrinsic spatial efficiency method is a general and absolute method to determine the absolute efficiency of a spectroscopy system for any extended sources, but this was only demonstrated experimentally for cylindrical sources. Due to the difficulty that the preparation of sources with any shape represents, the simplest way to do this is by the simulation of the spectroscopy system and the source. In this work we present the validation of the intrinsic spatial efficiency method for sources with different geometries and for photons with an energy of 661.65 keV. In the simulation the matrix effects (the auto-attenuation effect) are not considered, therefore these results are only preliminaries. The MC simulation is carried out using the FLUKA code and the absolute efficiency of the detector is determined using two methods: the statistical count of Full Energy Peak (FEP) area (traditional method) and the intrinsic spatial efficiency method. The obtained results show total agreement between the absolute efficiencies determined by the traditional method and the intrinsic spatial efficiency method. The relative bias is lesser than 1% in all cases.
Design, modeling, simulation and evaluation of a distributed energy system
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 of the Atmospheric Boundary Layer for Wind Energy Applications
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
Energy Technology Data Exchange (ETDEWEB)
Kandel, Saugat; Salomon-Ferrer, Romelia; Larsen, Adrien B.; Vaidehi, Nagarajan, E-mail: nvaidehi@coh.org [Division of Immunology, Beckman Research Institute of the City of Hope, Duarte, California 91010 (United States); Jain, Abhinandan, E-mail: Abhi.Jain@jpl.nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109 (United States)
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
Energy Technology Data Exchange (ETDEWEB)
Goldberg, L. F.; Steigauf, B.
2013-04-01
A split simulation whole building energy/3-dimensional earth contact model (termed the BUFETS/EnergyPlus Model or BEM) capable of modeling the full range of foundation systems found in the target retrofit housing stock has been extensively tested. These foundation systems that include abovegrade foundation walls, diabatic floors or slabs as well as lookout or walkout walls, currently cannot be modeled within BEopt.
Energy Technology Data Exchange (ETDEWEB)
Goldberg, Louise F. [NorthernSTAR Building America Partnership, Minneapolis, MN (United States); Steigauf, Brianna [NorthernSTAR Building America Partnership, Minneapolis, MN (United States)
2013-04-01
A split simulation whole building energy / 3-dimensional earth contact model (termed the BUFETS/EnergyPlus Model or BEM) capable of modeling the full range of foundation systems found in the target retrofit housing stock has been extensively tested. These foundation systems that include abovegrade foundation walls, diabatic floors or slabs as well as lookout or walkout walls, currently cannot be modeled within BEopt.
Simulations of structure formation in interacting dark energy cosmologies
International Nuclear Information System (INIS)
Baldi, M.
2009-01-01
The evidence in favor of a dark energy component dominating the Universe, and driving its presently accelerated expansion, has progressively grown during the last decade of cosmological observations. If this dark energy is given by a dynamic scalar field, it may also have a direct interaction with other matter fields in the Universe, in particular with cold dark matter. Such interaction would imprint new features on the cosmological background evolution as well as on the growth of cosmic structure, like an additional long-range fifth-force between massive particles, or a variation in time of the dark matter particle mass. We present here the implementation of these new physical effects in the N-body code GADGET-2, and we discuss the outcomes of a series of high-resolution N-body simulations for a selected family of interacting dark energy models. We interestingly find, in contrast with previous claims, that the inner overdensity of dark matter halos decreases in these models with respect to ΛCDM, and consistently halo concentrations show a progressive reduction for increasing couplings. Furthermore, the coupling induces a bias in the overdensities of cold dark matter and baryons that determines a decrease of the halo baryon fraction below its cosmological value. These results go in the direction of alleviating tensions between astrophysical observations and the predictions of the ΛCDM model on small scales, thereby opening new room for coupled dark energy models as an alternative to the cosmological constant.
Numerical Simulation of Tubular Pumping Systems with Different Regulation Methods
Zhu, Honggeng; Zhang, Rentian; Deng, Dongsheng; Feng, Xusong; Yao, Linbi
2010-06-01
Since the flow in tubular pumping systems is basically along axial direction and passes symmetrically through the impeller, most satisfying the basic hypotheses in the design of impeller and having higher pumping system efficiency in comparison with vertical pumping system, they are being widely applied to low-head pumping engineering. In a pumping station, the fluctuation of water levels in the sump and discharge pool is most common and at most time the pumping system runs under off-design conditions. Hence, the operation of pump has to be flexibly regulated to meet the needs of flow rates, and the selection of regulation method is as important as that of pump to reduce operation cost and achieve economic operation. In this paper, the three dimensional time-averaged Navier-Stokes equations are closed by RNG κ-ɛ turbulent model, and two tubular pumping systems with different regulation methods, equipped with the same pump model but with different designed system structures, are numerically simulated respectively to predict the pumping system performances and analyze the influence of regulation device and help designers make final decision in the selection of design schemes. The computed results indicate that the pumping system with blade-adjusting device needs longer suction box, and the increased hydraulic loss will lower the pumping system efficiency in the order of 1.5%. The pumping system with permanent magnet motor, by means of variable speed regulation, obtains higher system efficiency partly for shorter suction box and partly for different structure design. Nowadays, the varied speed regulation is realized by varied frequency device, the energy consumption of which is about 3˜4% of output power of the motor. Hence, when the efficiency of variable frequency device is considered, the total pumping system efficiency will probably be lower.
Deng, Nanjie; Zhang, Bin W; Levy, Ronald M
2015-06-09
The ability to accurately model solvent effects on free energy surfaces is important for understanding many biophysical processes including protein folding and misfolding, allosteric transitions, and protein–ligand binding. Although all-atom simulations in explicit solvent can provide an accurate model for biomolecules in solution, explicit solvent simulations are hampered by the slow equilibration on rugged landscapes containing multiple basins separated by barriers. In many cases, implicit solvent models can be used to significantly speed up the conformational sampling; however, implicit solvent simulations do not fully capture the effects of a molecular solvent, and this can lead to loss of accuracy in the estimated free energies. Here we introduce a new approach to compute free energy changes in which the molecular details of explicit solvent simulations are retained while also taking advantage of the speed of the implicit solvent simulations. In this approach, the slow equilibration in explicit solvent, due to the long waiting times before barrier crossing, is avoided by using a thermodynamic cycle which connects the free energy basins in implicit solvent and explicit solvent using a localized decoupling scheme. We test this method by computing conformational free energy differences and solvation free energies of the model system alanine dipeptide in water. The free energy changes between basins in explicit solvent calculated using fully explicit solvent paths agree with the corresponding free energy differences obtained using the implicit/explicit thermodynamic cycle to within 0.3 kcal/mol out of ∼3 kcal/mol at only ∼8% of the computational cost. We note that WHAM methods can be used to further improve the efficiency and accuracy of the implicit/explicit thermodynamic cycle.
Activity coefficients from molecular simulations using the OPAS method
Kohns, Maximilian; Horsch, Martin; Hasse, Hans
2017-10-01
A method for determining activity coefficients by molecular dynamics simulations is presented. It is an extension of the OPAS (osmotic pressure for the activity of the solvent) method in previous work for studying the solvent activity in electrolyte solutions. That method is extended here to study activities of all components in mixtures of molecular species. As an example, activity coefficients in liquid mixtures of water and methanol are calculated for 298.15 K and 323.15 K at 1 bar using molecular models from the literature. These dense and strongly interacting mixtures pose a significant challenge to existing methods for determining activity coefficients by molecular simulation. It is shown that the new method yields accurate results for the activity coefficients which are in agreement with results obtained with a thermodynamic integration technique. As the partial molar volumes are needed in the proposed method, the molar excess volume of the system water + methanol is also investigated.
Method for the transmission of energy
International Nuclear Information System (INIS)
Weissenbach, B.
1976-01-01
According ot the invention, chemical energy and/or chemically bound latent energy from a heat source (preferably from a nuclear reactor), is conveyed to a consumer by means of ordinary, saturated hydrocarbons, or their oxygen-containing derivates (preferably methanol), or synthesis gas in open- or closed-cycle systems. (GG) [de
Energy Technology Data Exchange (ETDEWEB)
Agertz, Oscar; Kravtsov, Andrey V.; Leitner, Samuel N.; Gnedin, Nickolay Y.
2013-05-21
We investigate the momentum and energy budget of stellar feedback during different stages of stellar evolution, and study its impact on the interstellar medium (ISM) using simulations of local star-forming regions and galactic disks at the resolution affordable in modern cosmological zoom-in simulations. In particular, we present a novel subgrid model for the momentum injection due to radiation pressure and stellar winds from massive stars during early, pre-supernova (pre-SN) evolutionary stages of young star clusters. Early injection of momentum acts to clear out dense gas in star-forming regions, hence limiting star formation. The reduced gas density mitigates radiative losses of thermal feedback energy from subsequent SN explosions. The detailed impact of stellar feedback depends sensitively on the implementation and choice of parameters. Somewhat encouragingly, we find that implementations in which feedback is efficient lead to approximate self-regulation of the global star formation efficiency. We compare simulation results using our feedback implementation to other phenomenological feedback methods, where thermal feedback energy is allowed to dissipate over timescales longer than the formal gas cooling time. We find that simulations with maximal momentum injection suppress star formation to a similar degree as is found in simulations adopting adiabatic thermal feedback. However, different feedback schemes are found to produce significant differences in the density and thermodynamic structure of the ISM, and are hence expected to have a qualitatively different impact on galaxy evolution.
International Nuclear Information System (INIS)
Agertz, Oscar; Kravtsov, Andrey V.; Leitner, Samuel N.; Gnedin, Nickolay Y.
2013-01-01
We investigate the momentum and energy budget of stellar feedback during different stages of stellar evolution, and study its impact on the interstellar medium (ISM) using simulations of local star-forming regions and galactic disks at the resolution affordable in modern cosmological zoom-in simulations. In particular, we present a novel subgrid model for the momentum injection due to radiation pressure and stellar winds from massive stars during early, pre-supernova (pre-SN) evolutionary stages of young star clusters. Early injection of momentum acts to clear out dense gas in star-forming regions, hence limiting star formation. The reduced gas density mitigates radiative losses of thermal feedback energy from subsequent SN explosions. The detailed impact of stellar feedback depends sensitively on the implementation and choice of parameters. Somewhat encouragingly, we find that implementations in which feedback is efficient lead to approximate self-regulation of the global star formation efficiency. We compare simulation results using our feedback implementation to other phenomenological feedback methods, where thermal feedback energy is allowed to dissipate over timescales longer than the formal gas cooling time. We find that simulations with maximal momentum injection suppress star formation to a similar degree as is found in simulations adopting adiabatic thermal feedback. However, different feedback schemes are found to produce significant differences in the density and thermodynamic structure of the ISM, and are hence expected to have a qualitatively different impact on galaxy evolution.
Simulation of the acoustic wave propagation using a meshless method
Directory of Open Access Journals (Sweden)
Bajko J.
2017-01-01
Full Text Available This paper presents numerical simulations of the acoustic wave propagation phenomenon modelled via Linearized Euler equations. A meshless method based on collocation of the strong form of the equation system is adopted. Moreover, the Weighted least squares method is used for local approximation of derivatives as well as stabilization technique in a form of spatial ltering. The accuracy and robustness of the method is examined on several benchmark problems.
Numerical simulation methods for wave propagation through optical waveguides
International Nuclear Information System (INIS)
Sharma, A.
1993-01-01
The simulation of the field propagation through waveguides requires numerical solutions of the Helmholtz equation. For this purpose a method based on the principle of orthogonal collocation was recently developed. The method is also applicable to nonlinear pulse propagation through optical fibers. Some of the salient features of this method and its application to both linear and nonlinear wave propagation through optical waveguides are discussed in this report. 51 refs, 8 figs, 2 tabs
A Simulation Framework for Optimal Energy Storage Sizing
Directory of Open Access Journals (Sweden)
Carlos Suazo-Martínez
2014-05-01
Full Text Available Despite the increasing interest in Energy Storage Systems (ESS, quantification of their technical and economical benefits remains a challenge. To assess the use of ESS, a simulation approach for ESS optimal sizing is presented. The algorithm is based on an adapted Unit Commitment, including ESS operational constraints, and the use of high performance computing (HPC. Multiple short-term simulations are carried out within a multiple year horizon. Evaluation is performed for Chile's Northern Interconnected Power System (SING. The authors show that a single year evaluation could lead to sub-optimal results when evaluating optimal ESS size. Hence, it is advisable to perform long-term evaluations of ESS. Additionally, the importance of detailed simulation for adequate assessment of ESS contributions and to fully capture storage value is also discussed. Furthermore, the robustness of the optimal sizing approach is evaluated by means of a sensitivity analyses. The results suggest that regulatory frameworks should recognize multiple value streams from storage in order to encourage greater ESS integration.
De Beer, Stephanie B A; Glättli, Alice; Hutzler, Johannes; Vermeulen, Nico P E; Oostenbrink, Chris
2011-07-30
4-Hydroxyphenylpyruvate dioxygenase is a relevant target in both pharmaceutical and agricultural research. We report on molecular dynamics simulations and free energy calculations on this enzyme, in complex with 12 inhibitors for which experimental affinities were determined. We applied the thermodynamic integration approach and the more efficient one-step perturbation. Even though simulations seem well converged and both methods show excellent agreement between them, the correlation with the experimental values remains poor. We investigate the effect of slight modifications on the charge distribution of these highly conjugated systems and find that accurate models can be obtained when using improved force field parameters. This study gives insight into the applicability of free energy methods and current limitations in force field parameterization. Copyright © 2011 Wiley Periodicals, Inc.
Reliability Verification of DBE Environment Simulation Test Facility by using Statistics Method
International Nuclear Information System (INIS)
Jang, Kyung Nam; Kim, Jong Soeg; Jeong, Sun Chul; Kyung Heum
2011-01-01
In the nuclear power plant, all the safety-related equipment including cables under the harsh environment should perform the equipment qualification (EQ) according to the IEEE std 323. There are three types of qualification methods including type testing, operating experience and analysis. In order to environmentally qualify the safety-related equipment using type testing method, not analysis or operation experience method, the representative sample of equipment, including interfaces, should be subjected to a series of tests. Among these tests, Design Basis Events (DBE) environment simulating test is the most important test. DBE simulation test is performed in DBE simulation test chamber according to the postulated DBE conditions including specified high-energy line break (HELB), loss of coolant accident (LOCA), main steam line break (MSLB) and etc, after thermal and radiation aging. Because most DBE conditions have 100% humidity condition, in order to trace temperature and pressure of DBE condition, high temperature steam should be used. During DBE simulation test, if high temperature steam under high pressure inject to the DBE test chamber, the temperature and pressure in test chamber rapidly increase over the target temperature. Therefore, the temperature and pressure in test chamber continue fluctuating during the DBE simulation test to meet target temperature and pressure. We should ensure fairness and accuracy of test result by confirming the performance of DBE environment simulation test facility. In this paper, in order to verify reliability of DBE environment simulation test facility, statistics method is used
Advance in research on aerosol deposition simulation methods
International Nuclear Information System (INIS)
Liu Keyang; Li Jingsong
2011-01-01
A comprehensive analysis of the health effects of inhaled toxic aerosols requires exact data on airway deposition. A knowledge of the effect of inhaled drugs is essential to the optimization of aerosol drug delivery. Sophisticated analytical deposition models can be used for the computation of total, regional and generation specific deposition efficiencies. The continuously enhancing computer seem to allow us to study the particle transport and deposition in more and more realistic airway geometries with the help of computational fluid dynamics (CFD) simulation method. In this article, the trends in aerosol deposition models and lung models, and the methods for achievement of deposition simulations are also reviewed. (authors)
Finite element method for simulation of the semiconductor devices
International Nuclear Information System (INIS)
Zikatanov, L.T.; Kaschiev, M.S.
1991-01-01
An iterative method for solving the system of nonlinear equations of the drift-diffusion representation for the simulation of the semiconductor devices is worked out. The Petrov-Galerkin method is taken for the discretization of these equations using the bilinear finite elements. It is shown that the numerical scheme is a monotonous one and there are no oscillations of the solutions in the region of p-n transition. The numerical calculations of the simulation of one semiconductor device are presented. 13 refs.; 3 figs
Reliability analysis of neutron transport simulation using Monte Carlo method
International Nuclear Information System (INIS)
Souza, Bismarck A. de; Borges, Jose C.
1995-01-01
This work presents a statistical and reliability analysis covering data obtained by computer simulation of neutron transport process, using the Monte Carlo method. A general description of the method and its applications is presented. Several simulations, corresponding to slowing down and shielding problems have been accomplished. The influence of the physical dimensions of the materials and of the sample size on the reliability level of results was investigated. The objective was to optimize the sample size, in order to obtain reliable results, optimizing computation time. (author). 5 refs, 8 figs
Simulation of Energy Savings in Automotive Coatings Processes
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
Energy consumption program: A computer model simulating energy loads in buildings
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.
Lee, M.W.; Meuwly, M.
2013-01-01
The evaluation of hydration free energies is a sensitive test to assess force fields used in atomistic simulations. We showed recently that the vibrational relaxation times, 1D- and 2D-infrared spectroscopies for CN(-) in water can be quantitatively described from molecular dynamics (MD) simulations with multipolar force fields and slightly enlarged van der Waals radii for the C- and N-atoms. To validate such an approach, the present work investigates the solvation free energy of cyanide in water using MD simulations with accurate multipolar electrostatics. It is found that larger van der Waals radii are indeed necessary to obtain results close to the experimental values when a multipolar force field is used. For CN(-), the van der Waals ranges refined in our previous work yield hydration free energy between -72.0 and -77.2 kcal mol(-1), which is in excellent agreement with the experimental data. In addition to the cyanide ion, we also study the hydroxide ion to show that the method used here is readily applicable to similar systems. Hydration free energies are found to sensitively depend on the intermolecular interactions, while bonded interactions are less important, as expected. We also investigate in the present work the possibility of applying the multipolar force field in scoring trajectories generated using computationally inexpensive methods, which should be useful in broader parametrization studies with reduced computational resources, as scoring is much faster than the generation of the trajectories.
Energy Technology Data Exchange (ETDEWEB)
Sun, Kaiyu; Yan, Da; Hong, Tianzhen; Guo, Siyue
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 office 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.
Investigation of Compton scattering correction methods in cardiac SPECT by Monte Carlo simulations
International Nuclear Information System (INIS)
Silva, A.M. Marques da; Furlan, A.M.; Robilotta, C.C.
2001-01-01
The goal of this work was the use of Monte Carlo simulations to investigate the effects of two scattering correction methods: dual energy window (DEW) and dual photopeak window (DPW), in quantitative cardiac SPECT reconstruction. MCAT torso-cardiac phantom, with 99m Tc and non-uniform attenuation map was simulated. Two different photopeak windows were evaluated in DEW method: 15% and 20%. Two 10% wide subwindows centered symmetrically within the photopeak were used in DPW method. Iterative ML-EM reconstruction with modified projector-backprojector for attenuation correction was applied. Results indicated that the choice of the scattering and photopeak windows determines the correction accuracy. For the 15% window, fitted scatter fraction gives better results than k = 0.5. For the 20% window, DPW is the best method, but it requires parameters estimation using Monte Carlo simulations. (author)
Methods of Comprehensive Assessment for China’s Energy Sustainability
Xu, Zhijin; Song, Yankui
2018-02-01
In order to assess the sustainable development of China’s energy objectively and accurately, we need to establish a reasonable indicator system for energy sustainability and make a targeted comprehensive assessment with the scientific methods. This paper constructs a comprehensive indicator system for energy sustainability from five aspects of economy, society, environment, energy resources and energy technology based on the theory of sustainable development and the theory of symbiosis. On this basis, it establishes and discusses the assessment models and the general assessment methods for energy sustainability with the help of fuzzy mathematics. It is of some reference for promoting the sustainable development of China’s energy, economy and society.
MONTE CARLO METHOD AND APPLICATION IN @RISK SIMULATION SYSTEM
Directory of Open Access Journals (Sweden)
Gabriela Ižaríková
2015-12-01
Full Text Available The article is an example of using the software simulation @Risk designed for simulation in Microsoft Excel spread sheet, demonstrated the possibility of its usage in order to show a universal method of solving problems. The simulation is experimenting with computer models based on the real production process in order to optimize the production processes or the system. The simulation model allows performing a number of experiments, analysing them, evaluating, optimizing and afterwards applying the results to the real system. A simulation model in general is presenting modelling system by using mathematical formulations and logical relations. In the model is possible to distinguish controlled inputs (for instance investment costs and random outputs (for instance demand, which are by using a model transformed into outputs (for instance mean value of profit. In case of a simulation experiment at the beginning are chosen controlled inputs and random (stochastic outputs are generated randomly. Simulations belong into quantitative tools, which can be used as a support for a decision making.
MAESTRO: Methods and Advanced Equipment for Simulation and Treatment in Radio-Oncology
Barthe, Jean; Hugon, Régis; Nicolai, Jean Philippe
2007-12-01
The integrated project MAESTRO (Methods and Advanced Equipment for Simulation and Treatment in Radio-Oncology) under contract with the European Commission in life sciences FP6 (LSHC-CT-2004-503564), concerns innovative research to develop and validate in clinical conditions, advanced methods and equipment needed in cancer treatment for new modalities in high-conformal external radiotherapy using electrons, photons and protons beams of high energy.
An Energy Efficiency Evaluation Method Based on Energy Baseline for Chemical Industry
Yao, Dong-mei; Zhang, Xin; Wang, Ke-feng; Zou, Tao; Wang, Dong; Qian, Xin-hua
2016-01-01
According to the requirements and structure of ISO 50001 energy management system, this study proposes an energy efficiency evaluation method based on energy baseline for chemical industry. Using this method, the energy plan implementation effect in the processes of chemical production can be evaluated quantitatively, and evidences for system fault diagnosis can be provided. This method establishes the energy baseline models which can meet the demand of the different kinds of production proce...
Mirsadeghi, M.
2011-01-01
Building performance simulation (BPS) is widely applied to analyse heat, air and moisture (HAM) related issues in the indoor environment such as energy consumption, thermal comfort, condensation and mould growth. The uncertainty associated with such simulations can be high, and incorrect simulation
Energy Technology Data Exchange (ETDEWEB)
HOLM,ELIZABETH A.; BATTAILE,CORBETT C.; BUCHHEIT,THOMAS E.; FANG,HUEI ELIOT; RINTOUL,MARK DANIEL; VEDULA,VENKATA R.; GLASS,S. JILL; KNOROVSKY,GERALD A.; NEILSEN,MICHAEL K.; WELLMAN,GERALD W.; SULSKY,DEBORAH; SHEN,YU-LIN; SCHREYER,H. BUCK
2000-04-01
Computational materials simulations have traditionally focused on individual phenomena: grain growth, crack propagation, plastic flow, etc. However, real materials behavior results from a complex interplay between phenomena. In this project, the authors explored methods for coupling mesoscale simulations of microstructural evolution and micromechanical response. In one case, massively parallel (MP) simulations for grain evolution and microcracking in alumina stronglink materials were dynamically coupled. In the other, codes for domain coarsening and plastic deformation in CuSi braze alloys were iteratively linked. this program provided the first comparison of two promising ways to integrate mesoscale computer codes. Coupled microstructural/micromechanical codes were applied to experimentally observed microstructures for the first time. In addition to the coupled codes, this project developed a suite of new computational capabilities (PARGRAIN, GLAD, OOF, MPM, polycrystal plasticity, front tracking). The problem of plasticity length scale in continuum calculations was recognized and a solution strategy was developed. The simulations were experimentally validated on stockpile materials.
Heavy Bearings Exploitation Energy and Reduction Methods
Szekely, V. G.; Cioară, R.
2016-11-01
The global trend of resource conservation so as “not to compromise the ability of future generation's development” is the fundamental basis of the concept of sustainable development. Concordant with this, the energy efficiency of products is increasingly discussed and frequently taken into account in the design stage. In more cases a product is more appreciated and more attractive as the energy consumption and its associated materials are lower. In the production stage, said consumption advantages primarily the manufacturer, particularly through low consumption thereof. In the operational phase, low energy and materials consumption represents an user advantage and it's a major argument in the decision to purchase and use a particular product. Heavy bearings are frequent products used in wind turbines that are producing non-conventional “clean” energy, as windmills. An enhanced energy efficiency bearing contributes to the enhancement of the overall efficiency of the wind turbines. Based on a suitable mathematical model, this paper identifies and recommends courses of action to reduce the operating energy of heavy bearing through the “cage” - which is the subject of a much larger research - with the highest priority. The identified actions may constitute from a set of requirements for the design stage of the heavy bearing predominantly oriented towards innovation-invention.
Simulation methods with extended stability for stiff biochemical Kinetics
Directory of Open Access Journals (Sweden)
Rué Pau
2010-08-01
Full Text Available Abstract Background With increasing computer power, simulating the dynamics of complex systems in chemistry and biology is becoming increasingly routine. The modelling of individual reactions in (biochemical systems involves a large number of random events that can be simulated by the stochastic simulation algorithm (SSA. The key quantity is the step size, or waiting time, τ, whose value inversely depends on the size of the propensities of the different channel reactions and which needs to be re-evaluated after every firing event. Such a discrete event simulation may be extremely expensive, in particular for stiff systems where τ can be very short due to the fast kinetics of some of the channel reactions. Several alternative methods have been put forward to increase the integration step size. The so-called τ-leap approach takes a larger step size by allowing all the reactions to fire, from a Poisson or Binomial distribution, within that step. Although the expected value for the different species in the reactive system is maintained with respect to more precise methods, the variance at steady state can suffer from large errors as τ grows. Results In this paper we extend Poisson τ-leap methods to a general class of Runge-Kutta (RK τ-leap methods. We show that with the proper selection of the coefficients, the variance of the extended τ-leap can be well-behaved, leading to significantly larger step sizes. Conclusions The benefit of adapting the extended method to the use of RK frameworks is clear in terms of speed of calculation, as the number of evaluations of the Poisson distribution is still one set per time step, as in the original τ-leap method. The approach paves the way to explore new multiscale methods to simulate (biochemical systems.
Method for energy recovery of spent ERL beams
Energy Technology Data Exchange (ETDEWEB)
Marhauser, Frank; Hannon, Fay; Rimmer, Robert; Whitney, R. Roy
2018-01-16
A method for recovering energy from spent energy recovered linac (ERL) beams. The method includes adding a plurality of passive decelerating cavities at the beam dump of the ERL, adding one or more coupling waveguides between the passive decelerating cavities, setting an adequate external Q (Qext) to adjust to the beam loading situation, and extracting the RF energy through the coupling waveguides.
High viscosity fluid simulation using particle-based method
Chang, Yuanzhang
2011-03-01
We present a new particle-based method for high viscosity fluid simulation. In the method, a new elastic stress term, which is derived from a modified form of the Hooke\\'s law, is included in the traditional Navier-Stokes equation to simulate the movements of the high viscosity fluids. Benefiting from the Lagrangian nature of Smoothed Particle Hydrodynamics method, large flow deformation can be well handled easily and naturally. In addition, in order to eliminate the particle deficiency problem near the boundary, ghost particles are employed to enforce the solid boundary condition. Compared with Finite Element Methods with complicated and time-consuming remeshing operations, our method is much more straightforward to implement. Moreover, our method doesn\\'t need to store and compare to an initial rest state. The experimental results show that the proposed method is effective and efficient to handle the movements of highly viscous flows, and a large variety of different kinds of fluid behaviors can be well simulated by adjusting just one parameter. © 2011 IEEE.
Thermal energy storage devices, systems, and thermal energy storage device monitoring methods
Tugurlan, Maria; Tuffner, Francis K; Chassin, David P.
2016-09-13
Thermal energy storage devices, systems, and thermal energy storage device monitoring methods are described. According to one aspect, a thermal energy storage device includes a reservoir configured to hold a thermal energy storage medium, a temperature control system configured to adjust a temperature of the thermal energy storage medium, and a state observation system configured to provide information regarding an energy state of the thermal energy storage device at a plurality of different moments in time.
Simulation of energy use in buildings with multiple micro generators
International Nuclear Information System (INIS)
Karmacharya, S.; Putrus, G.; Underwood, C.P.; Mahkamov, K.; McDonald, S.; Alexakis, A.
2014-01-01
This paper focuses on the detailed modelling of micro combined heat and power (mCHP) modules and their interaction with other renewable micro generators in domestic applications based on an integrated modular modelling approach. The simulation model has been developed using Matlab/Simulink and incorporates a Stirling engine mCHP module embedded in a lumped-parameter domestic energy model, together with contributions from micro wind and photovoltaic modules. The Stirling cycle component model is based on experimental identification of a domestic-scale system which includes start up and shut down characteristics. The integrated model is used to explore the interactions between the various energy supply technologies and results are presented showing the most favourable operating conditions that can be used to inform the design of advanced energy control strategies in building. The integrated model offers an improvement on previous models of this kind in that a fully-dynamic approach is adopted for the equipment and plant enabling fast changing load events such as switching on/off domestic loads and hot water, to be accurately captured at a minimum interval of 1 min. The model is applied to two typical 3- and 4-bedroom UK house types equipped with a mCHP module and two other renewable energy technologies for a whole year. Results of the two cases show that the electrical contribution of a Stirling engine type mCHP heavily depends on the thermal demand of the building and that up to 19% of the locally-generated electricity is exported whilst meeting a similar percentage of the overall annual electricity demand. Results also show that the increased number of switching of mCHP module has an impact on seasonal module efficiency and overall fuel utilisation. The results demonstrate the need for the analysis of equipment design and optimal sizing of thermal and electrical energy storage. -- Highlights: • Dynamic modelling of a building along with its space heating and hot
A Force Balanced Fragmentation Method for ab Initio Molecular Dynamic Simulation of Protein
Directory of Open Access Journals (Sweden)
Mingyuan Xu
2018-05-01
Full Text Available A force balanced generalized molecular fractionation with conjugate caps (FB-GMFCC method is proposed for ab initio molecular dynamic simulation of proteins. In this approach, the energy of the protein is computed by a linear combination of the QM energies of individual residues and molecular fragments that account for the two-body interaction of hydrogen bond between backbone peptides. The atomic forces on the caped H atoms were corrected to conserve the total force of the protein. Using this approach, ab initio molecular dynamic simulation of an Ace-(ALA9-NME linear peptide showed the conservation of the total energy of the system throughout the simulation. Further a more robust 110 ps ab initio molecular dynamic simulation was performed for a protein with 56 residues and 862 atoms in explicit water. Compared with the classical force field, the ab initio molecular dynamic simulations gave better description of the geometry of peptide bonds. Although further development is still needed, the current approach is highly efficient, trivially parallel, and can be applied to ab initio molecular dynamic simulation study of large proteins.
Aiding Design of Wave Energy Converters via Computational Simulations
Jebeli Aqdam, Hejar; Ahmadi, Babak; Raessi, Mehdi; Tootkaboni, Mazdak
2015-11-01
With the increasing interest in renewable energy sources, wave energy converters will continue to gain attention as a viable alternative to current electricity production methods. It is therefore crucial to develop computational tools for the design and analysis of wave energy converters. A successful design requires balance between the design performance and cost. Here an analytical solution is used for the approximate analysis of interactions between a flap-type wave energy converter (WEC) and waves. The method is verified using other flow solvers and experimental test cases. Then the model is used in conjunction with a powerful heuristic optimization engine, Charged System Search (CSS) to explore the WEC design space. CSS is inspired by charged particles behavior. It searches the design space by considering candidate answers as charged particles and moving them based on the Coulomb's laws of electrostatics and Newton's laws of motion to find the global optimum. Finally the impacts of changes in different design parameters on the power takeout of the superior WEC designs are investigated. National Science Foundation, CBET-1236462.
Computerized simulation methods for dose reduction, in radiodiagnosis
International Nuclear Information System (INIS)
Brochi, M.A.C.
1990-01-01
The present work presents computational methods that allow the simulation of any situation encountered in diagnostic radiology. Parameters of radiographic techniques that yield a standard radiographic image, previously chosen, and so could compare the dose of radiation absorbed by the patient is studied. Initially the method was tested on a simple system composed of 5.0 cm of water and 1.0 mm of aluminium and, after verifying experimentally its validity, it was applied in breast and arm fracture radiographs. It was observed that the choice of the filter material is not an important factor, because analogous behaviours were presented by aluminum, iron, copper, gadolinium, and other filters. A method of comparison of materials based on the spectral match is shown. Both the results given by this simulation method and the experimental measurements indicate an equivalence of brass and copper, both more efficient than aluminium, in terms of exposition time, but not of dose. (author)
Effective Energy Simulation and Optimal Design of Side-lit Buildings with Venetian Blinds
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
Vectorization of a particle simulation method for hypersonic rarefied flow
Mcdonald, Jeffrey D.; Baganoff, Donald
1988-01-01
An efficient particle simulation technique for hypersonic rarefied flows is presented at an algorithmic and implementation level. The implementation is for a vector computer architecture, specifically the Cray-2. The method models an ideal diatomic Maxwell molecule with three translational and two rotational degrees of freedom. Algorithms are designed specifically for compatibility with fine grain parallelism by reducing the number of data dependencies in the computation. By insisting on this compatibility, the method is capable of performing simulation on a much larger scale than previously possible. A two-dimensional simulation of supersonic flow over a wedge is carried out for the near-continuum limit where the gas is in equilibrium and the ideal solution can be used as a check on the accuracy of the gas model employed in the method. Also, a three-dimensional, Mach 8, rarefied flow about a finite-span flat plate at a 45 degree angle of attack was simulated. It utilized over 10 to the 7th particles carried through 400 discrete time steps in less than one hour of Cray-2 CPU time. This problem was chosen to exhibit the capability of the method in handling a large number of particles and a true three-dimensional geometry.
A multiscale quantum mechanics/electromagnetics method for device simulations.
Yam, ChiYung; Meng, Lingyi; Zhang, Yu; Chen, GuanHua
2015-04-07
Multiscale modeling has become a popular tool for research applying to different areas including materials science, microelectronics, biology, chemistry, etc. In this tutorial review, we describe a newly developed multiscale computational method, incorporating quantum mechanics into electronic device modeling with the electromagnetic environment included through classical electrodynamics. In the quantum mechanics/electromagnetics (QM/EM) method, the regions of the system where active electron scattering processes take place are treated quantum mechanically, while the surroundings are described by Maxwell's equations and a semiclassical drift-diffusion model. The QM model and the EM model are solved, respectively, in different regions of the system in a self-consistent manner. Potential distributions and current densities at the interface between QM and EM regions are employed as the boundary conditions for the quantum mechanical and electromagnetic simulations, respectively. The method is illustrated in the simulation of several realistic systems. In the case of junctionless field-effect transistors, transfer characteristics are obtained and a good agreement between experiments and simulations is achieved. Optical properties of a tandem photovoltaic cell are studied and the simulations demonstrate that multiple QM regions are coupled through the classical EM model. Finally, the study of a carbon nanotube-based molecular device shows the accuracy and efficiency of the QM/EM method.
A mixed finite element method for particle simulation in lasertron
International Nuclear Information System (INIS)
Le Meur, G.
1987-03-01
A particle simulation code is being developed with the aim to treat the motion of charged particles in electromagnetic devices, such as Lasertron. The paper describes the use of mixed finite element methods in computing the field components, without derivating them from scalar or vector potentials. Graphical results are shown
A simulation based engineering method to support HAZOP studies
DEFF Research Database (Denmark)
Enemark-Rasmussen, Rasmus; Cameron, David; Angelo, Per Bagge
2012-01-01
the conventional HAZOP procedure. The method systematically generates failure scenarios by considering process equipment deviations with pre-defined failure modes. The effect of failure scenarios is then evaluated using dynamic simulations -in this study the K-Spice® software used. The consequences of each failure...
Vectorization of a particle simulation method for hypersonic rarefied flow
International Nuclear Information System (INIS)
Mcdonald, J.D.; Baganoff, D.
1988-01-01
An efficient particle simulation technique for hypersonic rarefied flows is presented at an algorithmic and implementation level. The implementation is for a vector computer architecture, specifically the Cray-2. The method models an ideal diatomic Maxwell molecule with three translational and two rotational degrees of freedom. Algorithms are designed specifically for compatibility with fine grain parallelism by reducing the number of data dependencies in the computation. By insisting on this compatibility, the method is capable of performing simulation on a much larger scale than previously possible. A two-dimensional simulation of supersonic flow over a wedge is carried out for the near-continuum limit where the gas is in equilibrium and the ideal solution can be used as a check on the accuracy of the gas model employed in the method. Also, a three-dimensional, Mach 8, rarefied flow about a finite-span flat plate at a 45 degree angle of attack was simulated. It utilized over 10 to the 7th particles carried through 400 discrete time steps in less than one hour of Cray-2 CPU time. This problem was chosen to exhibit the capability of the method in handling a large number of particles and a true three-dimensional geometry. 14 references
Correction of measured multiplicity distributions by the simulated annealing method
International Nuclear Information System (INIS)
Hafidouni, M.
1993-01-01
Simulated annealing is a method used to solve combinatorial optimization problems. It is used here for the correction of the observed multiplicity distribution from S-Pb collisions at 200 GeV/c per nucleon. (author) 11 refs., 2 figs
A mixed finite element method for particle simulation in Lasertron
International Nuclear Information System (INIS)
Le Meur, G.
1987-01-01
A particle simulation code is being developed with the aim to treat the motion of charged particles in electromagnetic devices, such as Lasertron. The paper describes the use of mixed finite element methods in computing the field components, without derivating them from scalar or vector potentials. Graphical results are shown
Simulating water hammer with corrective smoothed particle method
Hou, Q.; Kruisbrink, A.C.H.; Tijsseling, A.S.; Keramat, A.
2012-01-01
The corrective smoothed particle method (CSPM) is used to simulate water hammer. The spatial derivatives in the water-hammer equations are approximated by a corrective kernel estimate. For the temporal derivatives, the Euler-forward time integration algorithm is employed. The CSPM results are in
Relative Free Energies for Hydration of Monovalent Ions from QM and QM/MM Simulations.
Lev, Bogdan; Roux, Benoît; Noskov, Sergei Yu
2013-09-10
Methods directly evaluating the hydration structure and thermodynamics of physiologically relevant cations (Na(+), K(+), Cl(-), etc.) have wide ranging applications in the fields of inorganic, physical, and biological chemistry. All-atom simulations based on accurate potential energy surfaces appear to offer a viable option for assessing the chemistry of ion solvation. Although MD and free energy simulations of ion solvation with classical force fields have proven their usefulness, a number of challenges still remain. One of them is the difficulty of force field benchmarking and validation against structural and thermodynamic data obtained for a condensed phase. Hybrid quantum mechanical/molecular mechanical (QM/MM) models combined with sampling algorithms have the potential to provide an accurate solvation model and to incorporate the effects from the surrounding, which is often missing in gas-phase ab initio computations. Herein, we report the results from QM/MM free energy simulations of Na(+)/K(+) and Cl(-)/Br(-) hydration where we simultaneously characterized the relative thermodynamics of ion solvation and changes in the solvation structure. The Flexible Inner Region Ensemble Separator (FIRES) method was used to impose a spatial separation between QM region and the outer sphere of solvent molecules treated with the CHARMM27 force field. FEP calculations based on QM/MM simulations utilizing the CHARMM/deMon2k interface were performed with different basis set combinations for K(+)/Na(+) and Cl(-)/Br(-) perturbations to establish the dependence of the computed free energies on the basis set level. The dependence of the computed relative free energies on the size of the QM and MM regions is discussed. The current methodology offers an accurate description of structural and thermodynamic aspects of the hydration of alkali and halide ions in neat solvents and can be used to obtain thermodynamic data on ion solvation in condensed phase along with underlying
STUDY ON SIMULATION METHOD OF AVALANCHE : FLOW ANALYSIS OF AVALANCHE USING PARTICLE METHOD
塩澤, 孝哉
2015-01-01
In this paper, modeling for the simulation of the avalanche by a particle method is discussed. There are two kinds of the snow avalanches, one is the surface avalanche which shows a smoke-like flow, and another is the total-layer avalanche which shows a flow like Bingham fluid. In the simulation of the surface avalanche, the particle method in consideration of a rotation resistance model is used. The particle method by Bingham fluid is used in the simulation of the total-layer avalanche. At t...
Method of osmotic energy harvesting using responsive compounds and molecules
Hu, Xiao; Cai, Yufeng; Lai, Zhiping; Zhong, Yujiang
2017-01-01
The present invention discloses and claims a more efficient and economical method and system for osmotic energy production and capture using responsive compounds and molecules. The present invention is an energy harvest system enabled by stimuli
Efficient method for transport simulations in quantum cascade lasers
Directory of Open Access Journals (Sweden)
Maczka Mariusz
2017-01-01
Full Text Available An efficient method for simulating quantum transport in quantum cascade lasers is presented. The calculations are performed within a simple approximation inspired by Büttiker probes and based on a finite model for semiconductor superlattices. The formalism of non-equilibrium Green’s functions is applied to determine the selected transport parameters in a typical structure of a terahertz laser. Results were compared with those obtained for a infinite model as well as other methods described in literature.
A method of simulating and visualizing nuclear reactions
International Nuclear Information System (INIS)
Atwood, C.H.; Paul, K.M.
1994-01-01
Teaching nuclear reactions to students is difficult because the mechanisms are complex and directly visualizing them is impossible. As a teaching tool, the authors have developed a method of simulating nuclear reactions using colliding water droplets. Videotaping of the collisions, taken with a high shutter speed camera and run frame-by-frame, shows details of the collisions that are analogous to nuclear reactions. The method for colliding the water drops and videotaping the collisions are shown
Modeling and Simulation of a Wave Energy Converter INWAVE
Directory of Open Access Journals (Sweden)
Seung Kwan Song
2017-01-01
Full Text Available INGINE Inc. developed its own wave energy converter (WEC named INWAVE and has currently installed three prototype modules in Jeju Island, Korea. This device is an on-shore-type WEC that consists of a buoy, pulleys fixed to the sea-floor and a power take off module (PTO. Three ropes are moored tightly on the bottom of the buoy and connected to the PTO via the pulleys, which are moving back and forth according to the motion of the buoy. Since the device can harness wave energy from all six degrees of movement of the buoy, it is possible to extract energy efficiently even under low energy density conditions provided in the coastal areas. In the PTO module, the ratchet gears convert the reciprocating movement of the rope drum into a uni-directional rotation and determine the transmission of power from the relation of the angular velocities between the rope drum and the generator. In this process, the discontinuity of the power transmission occurs and causes the modeling divergence. Therefore, we introduce the concept of the virtual torsion spring in order to prevent the impact error in the ratchet gear module, thereby completing the PTO modeling. In this paper, we deal with dynamic analysis in the time domain, based on Newtonian mechanics and linear wave theory. We derive the combined dynamics of the buoy and PTO modules via geometric relation between the buoy and mooring ropes, then suggest the ratchet gear mechanism with the virtual torsion spring element to reduce the dynamic errors during the phase transitions. Time domain simulation is carried out under irregular waves that reflect the actual wave states of the installation area, and we evaluate the theoretical performance using the capture width ratio.
The method of planning the energy consumption for electricity market
Russkov, O. V.; Saradgishvili, S. E.
2017-10-01
The limitations of existing forecast models are defined. The offered method is based on game theory, probabilities theory and forecasting the energy prices relations. New method is the basis for planning the uneven energy consumption of industrial enterprise. Ecological side of the offered method is disclosed. The program module performed the algorithm of the method is described. Positive method tests at the industrial enterprise are shown. The offered method allows optimizing the difference between planned and factual consumption of energy every hour of a day. The conclusion about applicability of the method for addressing economic and ecological challenges is made.
A Biologically Inspired Energy-Efficient Duty Cycle Design Method for Wireless Sensor Networks
Directory of Open Access Journals (Sweden)
Jie Zhou
2017-01-01
Full Text Available The recent success of emerging wireless sensor networks technology has encouraged researchers to develop new energy-efficient duty cycle design algorithm in this field. The energy-efficient duty cycle design problem is a typical NP-hard combinatorial optimization problem. In this paper, we investigate an improved elite immune evolutionary algorithm (IEIEA strategy to optimize energy-efficient duty cycle design scheme and monitored area jointly to enhance the network lifetimes. Simulation results show that the network lifetime of the proposed IEIEA method increased compared to the other two methods, which means that the proposed method improves the full coverage constraints.
Modeling energy market dynamics using discrete event system simulation
International Nuclear Information System (INIS)
Gutierrez-Alcaraz, G.; Sheble, G.B.
2009-01-01
This paper proposes the use of Discrete Event System Simulation to study the interactions among fuel and electricity markets and consumers, and the decision-making processes of fuel companies (FUELCOs), generation companies (GENCOs), and consumers in a simple artificial energy market. In reality, since markets can reach a stable equilibrium or fail, it is important to observe how they behave in a dynamic framework. We consider a Nash-Cournot model in which marketers are depicted as Nash-Cournot players that determine supply to meet end-use consumption. Detailed engineering considerations such as transportation network flows are omitted, because the focus is upon the selection and use of appropriate market models to provide answers to policy questions. (author)
Design and Control of Full Scale Wave Energy Simulator System
DEFF Research Database (Denmark)
Pedersen, Henrik C.; Hansen, Anders Hedegaard; Hansen, Rico Hjerm
2012-01-01
For wave energy to become feasible it is a requirement that the efficiency and reliability of the power take-off (PTO) systems are significantly improved. The cost of installing and testing PTO-systems at sea are however very high, and the focus of the current paper is therefore on the design...... of a full scale wave simulator for testing PTO-systems for point absorbers. The main challenge is here to design a system, which mimics the behavior of a wave when interacting with a given PTO-system. The paper includes a description of the developed system, located at Aalborg University......, and the considerations behind the design. Based on the description a model of the system is presented, which, along with a description of the wave theory applied, makes the foundation for the control strategy. The objective of the control strategy is to emulate not only the wave behavior, but also the dynamic wave...
Theoretical Simulations of Materials for Nuclear Energy Applications
International Nuclear Information System (INIS)
Abrikosov, A.; Ponomareva, A.V.; Nikonov, A.Y.; Barannikova, S.A.; Dmitriev, A.I.
2014-01-01
We have demonstrated that state-of-the art theoretical calculations have a capability to predict thermodynamic and mechanical properties of materials with very high accuracy, comparable to the experimental accuracy. Considering Fe-Cr alloys, we have investigated the effect of multicomponent alloying on their phase stability, and we have shown that alloying elements Ni, Mn, and Mo, present in RPV steels, reduce the stability of low-Cr steels against binodal, as well as spinodal decomposition. Considering Zr-Nb alloys, we have demonstrated a possibility of obtaining their elastic moduli from ab initio electronic structure calculations. We argue that theoretical simulations represent valuable tool for a design of new materials for nuclear energy applications
Simulated Energy Usage for a Novel 6 DOF Articulated Robot
International Nuclear Information System (INIS)
Shaik, A A; Tlale, N; Bright, G
2014-01-01
The serial robot architecture is widespread in modern day manufacturing, and over the last few decades the technology has matured and settled to its current state. One drawback from the architecture however is the location of motors and gearboxes which are either at the joint it controls or close by. A novel hybrid 6 DOF robot was designed to move all the actuators to the robot base, and to control the desired axis through a set of connected links and gears, while maintaining the same workspace and dexterity. This would reduce the inertia of the movable part of the robot and some of the moment arms on the 3 axes required for translation of the 3 DOF spherical wrist. Doing so would decrease the energy requirements when compared to a 6 DOF serial robot. This paper focuses on the mathematical modelling and simulation of the novel hybrid machine design and compares it to an equivalent serial robot
METHOD FOR OPTIMIZING THE ENERGY OF PUMPS
Skovmose Kallesøe, Carsten; De Persis, Claudio
2013-01-01
The device for energy-optimization on operation of several centrifugal pumps controlled in rotational speed, in a hydraulic installation, begins firstly with determining which pumps as pilot pumps are assigned directly to a consumer and which pumps are hydraulically connected in series upstream of
Different methods for waste to energy transformation
Koning, J. de
1998-01-01
In the past 25 years, many technological developments have taken place in the thermal treatment of Municipal Solid Waste (MSW). Apart from the initials goal of the technology (i.e., volume reduction and inertisation), flue gas emissions, solid residues, energy efficiency and economics became
DEFF Research Database (Denmark)
Hansen, David Christoffer; Seco, Joao; Sørensen, Thomas Sangild
2015-01-01
Background. Accurate stopping power estimation is crucial for treatment planning in proton therapy, and the uncertainties in stopping power are currently the largest contributor to the employed dose margins. Dual energy x-ray computed tomography (CT) (clinically available) and proton CT (in...... development) have both been proposed as methods for obtaining patient stopping power maps. The purpose of this work was to assess the accuracy of proton CT using dual energy CT scans of phantoms to establish reference accuracy levels. Material and methods. A CT calibration phantom and an abdomen cross section...... phantom containing inserts were scanned with dual energy and single energy CT with a state-of-the-art dual energy CT scanner. Proton CT scans were simulated using Monte Carlo methods. The simulations followed the setup used in current prototype proton CT scanners and included realistic modeling...
A modeling method for hybrid energy behaviors in flexible machining systems
International Nuclear Information System (INIS)
Li, Yufeng; He, Yan; Wang, Yan; Wang, Yulin; Yan, Ping; Lin, Shenlong
2015-01-01
Increasingly environmental and economic pressures have led to great concerns regarding the energy consumption of machining systems. Understanding energy behaviors of flexible machining systems is a prerequisite for improving energy efficiency of these systems. This paper proposes a modeling method to predict energy behaviors in flexible machining systems. The hybrid energy behaviors not only depend on the technical specification related of machine tools and workpieces, but are significantly affected by individual production scenarios. In the method, hybrid energy behaviors are decomposed into Structure-related energy behaviors, State-related energy behaviors, Process-related energy behaviors and Assignment-related energy behaviors. The modeling method for the hybrid energy behaviors is proposed based on Colored Timed Object-oriented Petri Net (CTOPN). The former two types of energy behaviors are modeled by constructing the structure of CTOPN, whist the latter two types of behaviors are simulated by applying colored tokens and associated attributes. Machining on two workpieces in the experimental workshop were undertaken to verify the proposed modeling method. The results showed that the method can provide multi-perspective transparency on energy consumption related to machine tools, workpieces as well as production management, and is particularly suitable for flexible manufacturing system when frequent changes in machining systems are often encountered. - Highlights: • Energy behaviors in flexible machining systems are modeled in this paper. • Hybrid characteristics of energy behaviors are examined from multiple viewpoints. • Flexible modeling method CTOPN is used to predict the hybrid energy behaviors. • This work offers a multi-perspective transparency on energy consumption
Energy Technology Data Exchange (ETDEWEB)
Pletschen, Ingo; Rohr, Stephan [ThyssenKrupp Aufzugswerke GmbH, Neuhausen a.d.F. (Germany); Kennel, Ralph [Technische Univ. Muenchen (Germany)
2011-07-01
Elevator systems would be in principal a good example for a perpetuum mobile. While lifting loads and persons electrical energy is converted into potential energy and reconverted later. In practice these conversions are however lossy. So the aim for high energy efficiency is to minimize these losses. However, as a travel of an elevator consists in main parts of acceleration and deceleration, the exclusive consideration of the efficiency during constant speed is not sufficient. Thus a simulation environment is introduced which reliably determines the elevators' energy consumption. The simulation is validated at an elevator afterwards the different influences on the energy consumption of elevators are analyzed. (orig.)
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.
Quantum mechanical simulation methods for studying biological systems
International Nuclear Information System (INIS)
Bicout, D.; Field, M.
1996-01-01
Most known biological mechanisms can be explained using fundamental laws of physics and chemistry and a full understanding of biological processes requires a multidisciplinary approach in which all the tools of biology, chemistry and physics are employed. An area of research becoming increasingly important is the theoretical study of biological macromolecules where numerical experimentation plays a double role of establishing a link between theoretical models and predictions and allowing a quantitative comparison between experiments and models. This workshop brought researchers working on different aspects of the development and application of quantum mechanical simulation together, assessed the state-of-the-art in the field and highlighted directions for future research. Fourteen lectures (theoretical courses and specialized seminars) deal with following themes: 1) quantum mechanical calculations of large systems, 2) ab initio molecular dynamics where the calculation of the wavefunction and hence the energy and forces on the atoms for a system at a single nuclear configuration are combined with classical molecular dynamics algorithms in order to perform simulations which use a quantum mechanical potential energy surface, 3) quantum dynamical simulations, electron and proton transfer processes in proteins and in solutions and finally, 4) free seminars that helped to enlarge the scope of the workshop. (N.T.)
Meshfree simulation of avalanches with the Finite Pointset Method (FPM)
Michel, Isabel; Kuhnert, Jörg; Kolymbas, Dimitrios
2017-04-01
Meshfree methods are the numerical method of choice in case of applications which are characterized by strong deformations in conjunction with free surfaces or phase boundaries. In the past the meshfree Finite Pointset Method (FPM) developed by Fraunhofer ITWM (Kaiserslautern, Germany) has been successfully applied to problems in computational fluid dynamics such as water crossing of cars, water turbines, and hydraulic valves. Most recently the simulation of granular flows, e.g. soil interaction with cars (rollover), has also been tackled. This advancement is the basis for the simulation of avalanches. Due to the generalized finite difference formulation in FPM, the implementation of different material models is quite simple. We will demonstrate 3D simulations of avalanches based on the Drucker-Prager yield criterion as well as the nonlinear barodesy model. The barodesy model (Division of Geotechnical and Tunnel Engineering, University of Innsbruck, Austria) describes the mechanical behavior of soil by an evolution equation for the stress tensor. The key feature of successful and realistic simulations of avalanches - apart from the numerical approximation of the occurring differential operators - is the choice of the boundary conditions (slip, no-slip, friction) between the different phases of the flow as well as the geometry. We will discuss their influences for simplified one- and two-phase flow examples. This research is funded by the German Research Foundation (DFG) and the FWF Austrian Science Fund.
Zero-Point Energy Leakage in Quantum Thermal Bath Molecular Dynamics Simulations.
Brieuc, Fabien; Bronstein, Yael; Dammak, Hichem; Depondt, Philippe; Finocchi, Fabio; Hayoun, Marc
2016-12-13
The quantum thermal bath (QTB) has been presented as an alternative to path-integral-based methods to introduce nuclear quantum effects in molecular dynamics simulations. The method has proved to be efficient, yielding accurate results for various systems. However, the QTB method is prone to zero-point energy leakage (ZPEL) in highly anharmonic systems. This is a well-known problem in methods based on classical trajectories where part of the energy of the high-frequency modes is transferred to the low-frequency modes leading to a wrong energy distribution. In some cases, the ZPEL can have dramatic consequences on the properties of the system. Thus, we investigate the ZPEL by testing the QTB method on selected systems with increasing complexity in order to study the conditions and the parameters that influence the leakage. We also analyze the consequences of the ZPEL on the structural and vibrational properties of the system. We find that the leakage is particularly dependent on the damping coefficient and that increasing its value can reduce and, in some cases, completely remove the ZPEL. When using sufficiently high values for the damping coefficient, the expected energy distribution among the vibrational modes is ensured. In this case, the QTB method gives very encouraging results. In particular, the structural properties are well-reproduced. The dynamical properties should be regarded with caution although valuable information can still be extracted from the vibrational spectrum, even for large values of the damping term.
Energy-pointwise discrete ordinates transport methods
International Nuclear Information System (INIS)
Williams, M.L.; Asgari, M.; Tashakorri, R.
1997-01-01
A very brief description is given of a one-dimensional code, CENTRM, which computes a detailed, space-dependent flux spectrum in a pointwise-energy representation within the resolved resonance range. The code will become a component in the SCALE system to improve computation of self-shielded cross sections, thereby enhancing the accuracy of codes such as KENO. CENTRM uses discrete-ordinates transport theory with an arbitrary angular quadrature order and a Legendre expansion of scattering anisotropy for moderator materials and heavy nuclides. The CENTRM program provides capability to deterministically compute full energy range, space-dependent angular flux spectra, rigorously accounting for resonance fine-structure and scattering anisotropy effects
Method of transport simulation for electrons between 10eV and 30keV
International Nuclear Information System (INIS)
Terrissol, Michel.
1978-01-01
A transport simulation of low energy electrons in matter using a Monte-Carlo method and studying all the interactions of the electrons with atoms, molecules or assembly of them is described. Elastic scattering, ionization, excitation, plasmon creation, reorganization following inner-shell ionization, electron-hole pair creation ... are simulated individually by sampling of confirmed experimental or theoretical cross sections. So atomic and molecular gases, metals such as aluminium and liquid water have been studied. The simulation allows to follow the electrons until their energy reaches the atomic or molecular ionization potential of the irradiated matter. The entire trajectories of primary electron and of all secondaries set in motion are exactly reproduced. Several applications to multiple scattering, radiobiology, microdosimetry, electronic microscope are represented and some results are directly compared with experimental ones [fr
Macdonald, R. L.; Grover, M. S.; Schwartzentruber, T. E.; Panesi, M.
2018-02-01
This work presents the analysis of non-equilibrium energy transfer and dissociation of nitrogen molecules (N2(g+1Σ) ) using two different approaches: the direct molecular simulation (DMS) method and the coarse-grain quasi-classical trajectory (CG-QCT) method. The two methods are used to study thermochemical relaxation in a zero-dimensional isochoric and isothermal reactor in which the nitrogen molecules are heated to several thousand degrees Kelvin, forcing the system into strong non-equilibrium. The analysis considers thermochemical relaxation for temperatures ranging from 10 000 to 25 000 K. Both methods make use of the same potential energy surface for the N2(g+1Σ ) -N2(g+1Σ ) system taken from the NASA Ames quantum chemistry database. Within the CG-QCT method, the rovibrational energy levels of the electronic ground state of the nitrogen molecule are lumped into a reduced number of bins. Two different grouping strategies are used: the more conventional vibrational-based grouping, widely used in the literature, and energy-based grouping. The analysis of both the internal state populations and concentration profiles show excellent agreement between the energy-based grouping and the DMS solutions. During the energy transfer process, discrepancies arise between the energy-based grouping and DMS solution due to the increased importance of mode separation for low energy states. By contrast, the vibrational grouping, traditionally considered state-of-the-art, captures well the behavior of the energy relaxation but fails to consistently predict the dissociation process. The deficiency of the vibrational grouping model is due to the assumption of strict mode separation and equilibrium of rotational energy states. These assumptions result in errors predicting the energy contribution to dissociation from the rotational and vibrational modes, with rotational energy actually contributing 30%-40% of the energy required to dissociate a molecule. This work confirms the
A Parsimonious Bootstrap Method to Model Natural Inflow Energy Series
Directory of Open Access Journals (Sweden)
Fernando Luiz Cyrino Oliveira
2014-01-01
Full Text Available The Brazilian energy generation and transmission system is quite peculiar in its dimension and characteristics. As such, it can be considered unique in the world. It is a high dimension hydrothermal system with huge participation of hydro plants. Such strong dependency on hydrological regimes implies uncertainties related to the energetic planning, requiring adequate modeling of the hydrological time series. This is carried out via stochastic simulations of monthly inflow series using the family of Periodic Autoregressive models, PAR(p, one for each period (month of the year. In this paper it is shown the problems in fitting these models by the current system, particularly the identification of the autoregressive order “p” and the corresponding parameter estimation. It is followed by a proposal of a new approach to set both the model order and the parameters estimation of the PAR(p models, using a nonparametric computational technique, known as Bootstrap. This technique allows the estimation of reliable confidence intervals for the model parameters. The obtained results using the Parsimonious Bootstrap Method of Moments (PBMOM produced not only more parsimonious model orders but also adherent stochastic scenarios and, in the long range, lead to a better use of water resources in the energy operation planning.
Same Content, Different Methods: Comparing Lecture, Engaged Classroom, and Simulation.
Raleigh, Meghan F; Wilson, Garland Anthony; Moss, David Alan; Reineke-Piper, Kristen A; Walden, Jeffrey; Fisher, Daniel J; Williams, Tracy; Alexander, Christienne; Niceler, Brock; Viera, Anthony J; Zakrajsek, Todd
2018-02-01
There is a push to use classroom technology and active teaching methods to replace didactic lectures as the most prevalent format for resident education. This multisite collaborative cohort study involving nine residency programs across the United States compared a standard slide-based didactic lecture, a facilitated group discussion via an engaged classroom, and a high-fidelity, hands-on simulation scenario for teaching the topic of acute dyspnea. The primary outcome was knowledge retention at 2 to 4 weeks. Each teaching method was assigned to three different residency programs in the collaborative according to local resources. Learning objectives were determined by faculty. Pre- and posttest questions were validated and utilized as a measurement of knowledge retention. Each site administered the pretest, taught the topic of acute dyspnea utilizing their assigned method, and administered a posttest 2 to 4 weeks later. Differences between the groups were compared using paired t-tests. A total of 146 residents completed the posttest, and scores increased from baseline across all groups. The average score increased 6% in the standard lecture group (n=47), 11% in the engaged classroom (n=53), and 9% in the simulation group (n=56). The differences in improvement between engaged classroom and simulation were not statistically significant. Compared to standard lecture, both engaged classroom and high-fidelity simulation were associated with a statistically significant improvement in knowledge retention. Knowledge retention after engaged classroom and high-fidelity simulation did not significantly differ. More research is necessary to determine if different teaching methods result in different levels of comfort and skill with actual patient care.
Non-conventional energy and propulsion methods
International Nuclear Information System (INIS)
Valone, T.
1991-01-01
From the disaster of the Space Shuttle, Challenger, to the Kuwaiti oil well fires, we are reminded constantly of our dependence on dangerous, combustible fuels for energy and propulsion. Over the past ten years, there has been a considerable production of new and exciting inventions which defy conventional analysis. The term non-conventional was coined in 1980 by a Canadian engineer to designate a separate technical discipline for this type of endeavor. Since then, several conferences have been devoted solely to these inventions. Integrity Research Corp., an affiliate of the Institute, has made an effort to investigate each viable product, develop business plans for several to facilitate development and marketing, and in some cases, assign an engineering student intern to building a working prototype. Each inventor discussed in this presentation has produced a unique device for free energy generation or highly efficient force production. Included in this paper is also a short summary for non-specialists explaining the physics of free energy generation along with a working definition. The main topics of discussion include: space power, inertial propulsion, kinetobaric force, magnetic motors, thermal fluctuations, over-unity hat pumps, ambient temperature superconductivity and nuclear battery
Evaluation of a scattering correction method for high energy tomography
Tisseur, David; Bhatia, Navnina; Estre, Nicolas; Berge, Léonie; Eck, Daniel; Payan, Emmanuel
2018-01-01
One of the main drawbacks of Cone Beam Computed Tomography (CBCT) is the contribution of the scattered photons due to the object and the detector. Scattered photons are deflected from their original path after their interaction with the object. This additional contribution of the scattered photons results in increased measured intensities, since the scattered intensity simply adds to the transmitted intensity. This effect is seen as an overestimation in the measured intensity thus corresponding to an underestimation of absorption. This results in artifacts like cupping, shading, streaks etc. on the reconstructed images. Moreover, the scattered radiation provides a bias for the quantitative tomography reconstruction (for example atomic number and volumic mass measurement with dual-energy technique). The effect can be significant and difficult in the range of MeV energy using large objects due to higher Scatter to Primary Ratio (SPR). Additionally, the incident high energy photons which are scattered by the Compton effect are more forward directed and hence more likely to reach the detector. Moreover, for MeV energy range, the contribution of the photons produced by pair production and Bremsstrahlung process also becomes important. We propose an evaluation of a scattering correction technique based on the method named Scatter Kernel Superposition (SKS). The algorithm uses a continuously thickness-adapted kernels method. The analytical parameterizations of the scatter kernels are derived in terms of material thickness, to form continuously thickness-adapted kernel maps in order to correct the projections. This approach has proved to be efficient in producing better sampling of the kernels with respect to the object thickness. This technique offers applicability over a wide range of imaging conditions and gives users an additional advantage. Moreover, since no extra hardware is required by this approach, it forms a major advantage especially in those cases where
Papoulakos, Konstantinos; Pollakis, Giorgos; Moustakis, Yiannis; Markopoulos, Apostolis; Iliopoulou, Theano; Dimitriadis, Panayiotis; Koutsoyiannis, Demetris; Efstratiadis, Andreas
2017-04-01
Small islands are regarded as promising areas for developing hybrid water-energy systems that combine multiple sources of renewable energy with pumped-storage facilities. Essential element of such systems is the water storage component (reservoir), which implements both flow and energy regulations. Apparently, the representation of the overall water-energy management problem requires the simulation of the operation of the reservoir system, which in turn requires a faithful estimation of water inflows and demands of water and energy. Yet, in small-scale reservoir systems, this task in far from straightforward, since both the availability and accuracy of associated information is generally very poor. For, in contrast to large-scale reservoir systems, for which it is quite easy to find systematic and reliable hydrological data, in the case of small systems such data may be minor or even totally missing. The stochastic approach is the unique means to account for input data uncertainties within the combined water-energy management problem. Using as example the Livadi reservoir, which is the pumped storage component of the small Aegean island of Astypalaia, Greece, we provide a simulation framework, comprising: (a) a stochastic model for generating synthetic rainfall and temperature time series; (b) a stochastic rainfall-runoff model, whose parameters cannot be inferred through calibration and, thus, they are represented as correlated random variables; (c) a stochastic model for estimating water supply and irrigation demands, based on simulated temperature and soil moisture, and (d) a daily operation model of the reservoir system, providing stochastic forecasts of water and energy outflows. 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
Combining optimisation and simulation in an energy systems analysis of a Swedish iron foundry
International Nuclear Information System (INIS)
Mardan, Nawzad; Klahr, Roger
2012-01-01
To face global competition, and also reduce environmental and climate impact, industry-wide changes are needed, especially regarding energy use, which is closely related to global warming. Energy efficiency is therefore an essential task for the future as it has a significant impact on both business profits and the environment. For the analysis of possible changes in industrial production processes, and to choose what changes should be made, various modelling tools can be used as a decision support. This paper uses two types of energy analysis tool: Discrete Event Simulation (DES) and Energy Systems Optimisation (ESO). The aim of this study is to describe how a DES and an ESO tool can be combined. A comprehensive five-step approach is proposed for reducing system costs and making a more robust production system. A case study representing a new investment in part of a Swedish iron foundry is also included to illustrate the method's use. The method described in this paper is based on the use of the DES program QUEST and the ESO tool reMIND. The method combination itself is generic, i.e. other similar programs can be used as well with some adjustments and adaptations. The results from the case study show that when different boundary conditions are used the result obtained from the simulation tools is not optimum, in other words, the result shows only a feasible solution and not the best way to run the factory. It is therefore important to use the optimisation tool in such cases in order to obtain the optimum operating strategy. By using the optimisation tool a substantial amount of resources can be saved. The results also show that the combination of optimisation and simulation tools is useful to provide very detailed information about how the system works and to predict system behaviour as well as to minimise the system cost. -- Highlights: ► This study describes how a simulation and an optimisation tool can be combined. ► A case study representing a new
Energy Technology Data Exchange (ETDEWEB)
Wu, Y., E-mail: yican.wu@fds.org.cn [Inst. of Nuclear Energy Safety Technology, Hefei, Anhui (China)
2015-07-01
'Full text:' Super Monte Carlo Simulation Program for Advanced Nuclear Energy Systems (SuperMC) is a CAD-based Monte Carlo (MC) program for integrated simulation of nuclear system by making use of hybrid MC-deterministic method and advanced computer technologies. The main usability features are automatic modeling of geometry and physics, visualization and virtual simulation and cloud computing service. SuperMC 2.3, the latest version, can perform coupled neutron and photon transport calculation. SuperMC has been verified by more than 2000 benchmark models and experiments, and has been applied in tens of major nuclear projects, such as the nuclear design and analysis of International Thermonuclear Experimental Reactor (ITER) and China Lead-based reactor (CLEAR). Development and applications of SuperMC are introduced in this presentation. (author)
International Nuclear Information System (INIS)
Wu, Y.
2015-01-01
'Full text:' Super Monte Carlo Simulation Program for Advanced Nuclear Energy Systems (SuperMC) is a CAD-based Monte Carlo (MC) program for integrated simulation of nuclear system by making use of hybrid MC-deterministic method and advanced computer technologies. The main usability features are automatic modeling of geometry and physics, visualization and virtual simulation and cloud computing service. SuperMC 2.3, the latest version, can perform coupled neutron and photon transport calculation. SuperMC has been verified by more than 2000 benchmark models and experiments, and has been applied in tens of major nuclear projects, such as the nuclear design and analysis of International Thermonuclear Experimental Reactor (ITER) and China Lead-based reactor (CLEAR). Development and applications of SuperMC are introduced in this presentation. (author)
Computer simulation studies of high energy collision cascades
International Nuclear Information System (INIS)
Robinson, M.T.
1991-07-01
A modified binary collision approximation allowing the proper order of the collisions in time was used to study cascades in Cu and Au at primary kinetic energies up to 100 keV. Nonlinearities were approximated by letting already-stopped cascade atoms become targets in later collisions, using an improved method of locating potential targets to extend the calculations to energies much higher than heretofore. Beside the effect of the approximate nonlinearity, the effect of thermal disorder in the targets was examined. Target redisplacements reduce the damage in Cu by 3% at most, but in Au they reduce it by amounts up to 20% at 100 keV. Thermal disorder is also important: by disrupting crystal effects, the damage is reduced significantly. 11 refs., 4 figs
THREE-PHASE ENERGY SUPPLY SYSTEMS SIMULATION FOR THE TOTAL POWER LOSSES COMPONENTS ASSESSMENT
Directory of Open Access Journals (Sweden)
D.V. Tugay
2016-09-01
Full Text Available Purpose. The goal is to optimize a structure of Matlab-model of the three-phase energy supply system with power active filter. The mathematical model that describes the energy supply system modes of operation which contains additional losses is proposed. Methodology. We have applied concepts of the electrical circuits theory, mathematical modeling elements based on linear algebra and vector calculus, mathematical simulation in Matlab package. Results. We have developed two models of three-phase energy supply system. The first one is based on a vector representation, and the second one on the matrix representation of energy processes. Using these models we have solved the problem of maintaining unchanged the average useful power for 279 cases of energy supply system modes of operation. Originality. We have developed methods of mathematical analysis of a three-phase energy supply systems with polyharmonic voltages and currents in the symmetric and asymmetric modes. Practical value. We have created Matlab-model of a three-phase energy supply system with automated calculation of a correction factor. It allows reducing more than one order the time for energy processes elucidation in multiphase systems.
Advancement of DOE's EnergyPlus Building Energy Simulation Payment
Energy Technology Data Exchange (ETDEWEB)
Gu, Lixing [Florida Solar Energy Center, Cocoa, FL (United States); Shirey, Don [Florida Solar Energy Center, Cocoa, FL (United States); Raustad, Richard [Florida Solar Energy Center, Cocoa, FL (United States); Nigusse, Bereket [Florida Solar Energy Center, Cocoa, FL (United States); Sharma, Chandan [Florida Solar Energy Center, Cocoa, FL (United States); Lawrie, Linda [DHL Consulting, Bonn (Germany); Strand, Rick [Univ. of Illinois, Champaign, IL (United States); Pedersen, Curt [COPA, Panama City (Panama); Fisher, Dan [Oklahoma State Univ., Stillwater, OK (United States); Lee, Edwin [Oklahoma State Univ., Stillwater, OK (United States); Witte, Mike [GARD Analytics, Arlington Heights, IL (United States); Glazer, Jason [GARD Analytics, Arlington Heights, IL (United States); Barnaby, Chip [Wrightsoft, Lexington, MA (United States)
2011-09-30
significantly under this project, more enhancements are needed for further improvement to ensure that EnergyPlus is able to simulate the latest technologies and perform desired HAVC system operations for the development of next generation HVAC systems. Additional development will be performed under a new 5-year project managed by the National Renewable Energy Laboratory.
Radiobiological application of simulation of low-energy electron transport in liquid water
International Nuclear Information System (INIS)
Eudaldo Puell, Teresa.
1979-01-01
A Monte-Carlo transport simulation method, so-called event-after-event method provide results about trajectories of low-energy electrons, slowing-down in liquid water. A radiosensitive target model constituted by water cylindrical volumes, like the ones which surround the DNA molecule, is taken into consideration. The results characterizing the primary physical stage of radiation action, such as, space ionization distributions, interionization distance distributions ..., are obtained in some configurations constituted by single or several targets, in order to approach the biological reality [fr
Modified network simulation model with token method of bus access
Directory of Open Access Journals (Sweden)
L.V. Stribulevich
2013-08-01
Full Text Available Purpose. To study the characteristics of the local network with the marker method of access to the bus its modified simulation model was developed. Methodology. Defining characteristics of the network is carried out on the developed simulation model, which is based on the state diagram-layer network station with the mechanism of processing priorities, both in steady state and in the performance of control procedures: the initiation of a logical ring, the entrance and exit of the station network with a logical ring. Findings. A simulation model, on the basis of which can be obtained the dependencies of the application the maximum waiting time in the queue for different classes of access, and the reaction time usable bandwidth on the data rate, the number of network stations, the generation rate applications, the number of frames transmitted per token holding time, frame length was developed. Originality. The technique of network simulation reflecting its work in the steady condition and during the control procedures, the mechanism of priority ranking and handling was proposed. Practical value. Defining network characteristics in the real-time systems on railway transport based on the developed simulation model.
Thermal shale fracturing simulation using the Cohesive Zone Method (CZM)
Enayatpour, Saeid; van Oort, Eric; Patzek, Tadeusz
2018-01-01
Extensive research has been conducted over the past two decades to improve hydraulic fracturing methods used for hydrocarbon recovery from tight reservoir rocks such as shales. Our focus in this paper is on thermal fracturing of such tight rocks to enhance hydraulic fracturing efficiency. Thermal fracturing is effective in generating small fractures in the near-wellbore zone - or in the vicinity of natural or induced fractures - that may act as initiation points for larger fractures. Previous analytical and numerical results indicate that thermal fracturing in tight rock significantly enhances rock permeability, thereby enhancing hydrocarbon recovery. Here, we present a more powerful way of simulating the initiation and propagation of thermally induced fractures in tight formations using the Cohesive Zone Method (CZM). The advantages of CZM are: 1) CZM simulation is fast compared to similar models which are based on the spring-mass particle method or Discrete Element Method (DEM); 2) unlike DEM, rock material complexities such as scale-dependent failure behavior can be incorporated in a CZM simulation; 3) CZM is capable of predicting the extent of fracture propagation in rock, which is more difficult to determine in a classic finite element approach. We demonstrate that CZM delivers results for the challenging fracture propagation problem of similar accuracy to the eXtended Finite Element Method (XFEM) while reducing complexity and computational effort. Simulation results for thermal fracturing in the near-wellbore zone show the effect of stress anisotropy in fracture propagation in the direction of the maximum horizontal stress. It is shown that CZM can be used to readily obtain the extent and the pattern of induced thermal fractures.
Thermal shale fracturing simulation using the Cohesive Zone Method (CZM)
Enayatpour, Saeid
2018-05-17
Extensive research has been conducted over the past two decades to improve hydraulic fracturing methods used for hydrocarbon recovery from tight reservoir rocks such as shales. Our focus in this paper is on thermal fracturing of such tight rocks to enhance hydraulic fracturing efficiency. Thermal fracturing is effective in generating small fractures in the near-wellbore zone - or in the vicinity of natural or induced fractures - that may act as initiation points for larger fractures. Previous analytical and numerical results indicate that thermal fracturing in tight rock significantly enhances rock permeability, thereby enhancing hydrocarbon recovery. Here, we present a more powerful way of simulating the initiation and propagation of thermally induced fractures in tight formations using the Cohesive Zone Method (CZM). The advantages of CZM are: 1) CZM simulation is fast compared to similar models which are based on the spring-mass particle method or Discrete Element Method (DEM); 2) unlike DEM, rock material complexities such as scale-dependent failure behavior can be incorporated in a CZM simulation; 3) CZM is capable of predicting the extent of fracture propagation in rock, which is more difficult to determine in a classic finite element approach. We demonstrate that CZM delivers results for the challenging fracture propagation problem of similar accuracy to the eXtended Finite Element Method (XFEM) while reducing complexity and computational effort. Simulation results for thermal fracturing in the near-wellbore zone show the effect of stress anisotropy in fracture propagation in the direction of the maximum horizontal stress. It is shown that CZM can be used to readily obtain the extent and the pattern of induced thermal fractures.
Design, simulation, fabrication, and characterization of MEMS vibration energy harvesters
Oxaal, John
Energy harvesting from ambient sources has been a longtime goal for microsystem engineers. The energy available from ambient sources is substantial and could be used to power wireless micro devices, making them fully autonomous. Self-powered wireless sensors could have many applications in for autonomous monitoring of residential, commercial, industrial, geological, or biological environments. Ambient vibrations are of particular interest for energy harvesting as they are ubiquitous and have ample kinetic energy. In this work a MEMS device for vibration energy harvesting using a variable capacitor structure is presented. The nonlinear electromechanical dynamics of a gap-closing type structure is experimentally studied. Important experimental considerations such as the importance of reducing off-axis vibration during testing, characterization methods, dust contamination, and the effect of grounding on parasitic capacitance are discussed. A comprehensive physics based model is developed and validated with two different microfabricated devices. To achieve maximal power, devices with high aspect ratio electrodes and a novel two-level stopper system are designed and fabricated. The maximum achieved power from the MEMS device when driven by sinusoidal vibrations was 3.38 muW. Vibrations from HVAC air ducts, which have a primary frequency of 65 Hz and amplitude of 155 mgrms, are targeted as the vibration source and devices are designed for maximal power harvesting potential at those conditions. Harvesting from the air ducts, the devices reached 118 nW of power. When normalized to the operating conditions, the best figure of merit of the devices tested was an order of magnitude above state-of-the-art of the devices (1.24E-6).
Hybrid numerical methods for multiscale simulations of subsurface biogeochemical processes
International Nuclear Information System (INIS)
Scheibe, T D; Tartakovsky, A M; Tartakovsky, D M; Redden, G D; Meakin, P
2007-01-01
Many subsurface flow and transport problems of importance today involve coupled non-linear flow, transport, and reaction in media exhibiting complex heterogeneity. In particular, problems involving biological mediation of reactions fall into this class of problems. Recent experimental research has revealed important details about the physical, chemical, and biological mechanisms involved in these processes at a variety of scales ranging from molecular to laboratory scales. However, it has not been practical or possible to translate detailed knowledge at small scales into reliable predictions of field-scale phenomena important for environmental management applications. A large assortment of numerical simulation tools have been developed, each with its own characteristic scale. Important examples include 1. molecular simulations (e.g., molecular dynamics); 2. simulation of microbial processes at the cell level (e.g., cellular automata or particle individual-based models); 3. pore-scale simulations (e.g., lattice-Boltzmann, pore network models, and discrete particle methods such as smoothed particle hydrodynamics); and 4. macroscopic continuum-scale simulations (e.g., traditional partial differential equations solved by finite difference or finite element methods). While many problems can be effectively addressed by one of these models at a single scale, some problems may require explicit integration of models across multiple scales. We are developing a hybrid multi-scale subsurface reactive transport modeling framework that integrates models with diverse representations of physics, chemistry and biology at different scales (sub-pore, pore and continuum). The modeling framework is being designed to take advantage of advanced computational technologies including parallel code components using the Common Component Architecture, parallel solvers, gridding, data and workflow management, and visualization. This paper describes the specific methods/codes being used at each
Application of Macro Response Monte Carlo method for electron spectrum simulation
International Nuclear Information System (INIS)
Perles, L.A.; Almeida, A. de
2007-01-01
During the past years several variance reduction techniques for Monte Carlo electron transport have been developed in order to reduce the electron computation time transport for absorbed dose distribution. We have implemented the Macro Response Monte Carlo (MRMC) method to evaluate the electron spectrum which can be used as a phase space input for others simulation programs. Such technique uses probability distributions for electron histories previously simulated in spheres (called kugels). These probabilities are used to sample the primary electron final state, as well as the creation secondary electrons and photons. We have compared the MRMC electron spectra simulated in homogeneous phantom against the Geant4 spectra. The results showed an agreement better than 6% in the spectra peak energies and that MRMC code is up to 12 time faster than Geant4 simulations
Electrical appliance energy consumption control methods and electrical energy consumption systems
Donnelly, Matthew K [Kennewick, WA; Chassin, David P [Pasco, WA; Dagle, Jeffery E [Richland, WA; Kintner-Meyer, Michael [Richland, WA; Winiarski, David W [Kennewick, WA; Pratt, Robert G [Kennewick, WA; Boberly-Bartis, Anne Marie [Alexandria, VA
2006-03-07
Electrical appliance energy consumption control methods and electrical energy consumption systems are described. In one aspect, an electrical appliance energy consumption control method includes providing an electrical appliance coupled with a power distribution system, receiving electrical energy within the appliance from the power distribution system, consuming the received electrical energy using a plurality of loads of the appliance, monitoring electrical energy of the power distribution system, and adjusting an amount of consumption of the received electrical energy via one of the loads of the appliance from an initial level of consumption to an other level of consumption different than the initial level of consumption responsive to the monitoring.
Electrical appliance energy consumption control methods and electrical energy consumption systems
Donnelly, Matthew K [Kennewick, WA; Chassin, David P [Pasco, WA; Dagle, Jeffery E [Richland, WA; Kintner-Meyer, Michael [Richland, WA; Winiarski, David W [Kennewick, WA; Pratt, Robert G [Kennewick, WA; Boberly-Bartis, Anne Marie [Alexandria, VA
2008-09-02
Electrical appliance energy consumption control methods and electrical energy consumption systems are described. In one aspect, an electrical appliance energy consumption control method includes providing an electrical appliance coupled with a power distribution system, receiving electrical energy within the appliance from the power distribution system, consuming the received electrical energy using a plurality of loads of the appliance, monitoring electrical energy of the power distribution system, and adjusting an amount of consumption of the received electrical energy via one of the loads of the appliance from an initial level of consumption to an other level of consumption different than the initial level of consumption responsive to the monitoring.
Discrete Particle Method for Simulating Hypervelocity Impact Phenomena
Directory of Open Access Journals (Sweden)
Erkai Watson
2017-04-01
Full Text Available In this paper, we introduce a computational model for the simulation of hypervelocity impact (HVI phenomena which is based on the Discrete Element Method (DEM. Our paper constitutes the first application of DEM to the modeling and simulating of impact events for velocities beyond 5 kms-1. We present here the results of a systematic numerical study on HVI of solids. For modeling the solids, we use discrete spherical particles that interact with each other via potentials. In our numerical investigations we are particularly interested in the dynamics of material fragmentation upon impact. We model a typical HVI experiment configuration where a sphere strikes a thin plate and investigate the properties of the resulting debris cloud. We provide a quantitative computational analysis of the resulting debris cloud caused by impact and a comprehensive parameter study by varying key parameters of our model. We compare our findings from the simulations with recent HVI experiments performed at our institute. Our findings are that the DEM method leads to very stable, energy–conserving simulations of HVI scenarios that map the experimental setup where a sphere strikes a thin plate at hypervelocity speed. Our chosen interaction model works particularly well in the velocity range where the local stresses caused by impact shock waves markedly exceed the ultimate material strength.
Acceleration of coupled granular flow and fluid flow simulations in pebble bed energy systems
International Nuclear Information System (INIS)
Li, Yanheng; Ji, Wei
2013-01-01
Highlights: ► Fast simulation of coupled pebble flow and coolant flow in PBR systems is studied. ► Dimension reduction based on axisymmetric geometry shows significant speedup. ► Relaxation of coupling frequency is investigated and an optimal range is determined. ► A total of 80% efficiency increase is achieved by the two fast strategies. ► Fast strategies can be applied to simulating other general fluidized bed systems. -- Abstract: Fast and accurate approaches to simulating the coupled particle flow and fluid flow are of importance to the analysis of large particle-fluid systems. This is especially needed when one tries to simulate pebble flow and coolant flow in Pebble Bed Reactor (PBR) energy systems on a routine basis. As one of the Generation IV designs, the PBR design is a promising nuclear energy system with high fuel performance and inherent safety. A typical PBR core can be modeled as a particle-fluid system with strong interactions among pebbles, coolants and reactor walls. In previous works, the coupled Discrete Element Method (DEM)-Computational Fluid Dynamics (CFD) approach has been investigated and applied to modeling PBR systems. However, the DEM-CFD approach is computationally expensive due to large amounts of pebbles in PBR systems. This greatly restricts the PBR analysis for the real time prediction and inclusion of more physics. In this work, based on the symmetry of the PBR geometry and the slow motion characteristics of the pebble flow, two acceleration strategies are proposed. First, a simplified 3D-DEM/2D-CFD approach is proposed to speed up the DEM-CFD simulation without loss of accuracy. Pebble flow is simulated by a full 3D DEM, while the coolant flow field is calculated with a 2D CFD simulation by averaging variables along the annular direction in the cylindrical and annular geometries. Second, based on the slow motion of pebble flow, the impact of the coupling frequency on the computation accuracy and efficiency is
Acceleration of coupled granular flow and fluid flow simulations in pebble bed energy systems
Energy Technology Data Exchange (ETDEWEB)
Li, Yanheng, E-mail: liy19@rpi.edu [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY (United States); Ji, Wei, E-mail: jiw2@rpi.edu [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY (United States)
2013-05-15
Highlights: ► Fast simulation of coupled pebble flow and coolant flow in PBR systems is studied. ► Dimension reduction based on axisymmetric geometry shows significant speedup. ► Relaxation of coupling frequency is investigated and an optimal range is determined. ► A total of 80% efficiency increase is achieved by the two fast strategies. ► Fast strategies can be applied to simulating other general fluidized bed systems. -- Abstract: Fast and accurate approaches to simulating the coupled particle flow and fluid flow are of importance to the analysis of large particle-fluid systems. This is especially needed when one tries to simulate pebble flow and coolant flow in Pebble Bed Reactor (PBR) energy systems on a routine basis. As one of the Generation IV designs, the PBR design is a promising nuclear energy system with high fuel performance and inherent safety. A typical PBR core can be modeled as a particle-fluid system with strong interactions among pebbles, coolants and reactor walls. In previous works, the coupled Discrete Element Method (DEM)-Computational Fluid Dynamics (CFD) approach has been investigated and applied to modeling PBR systems. However, the DEM-CFD approach is computationally expensive due to large amounts of pebbles in PBR systems. This greatly restricts the PBR analysis for the real time prediction and inclusion of more physics. In this work, based on the symmetry of the PBR geometry and the slow motion characteristics of the pebble flow, two acceleration strategies are proposed. First, a simplified 3D-DEM/2D-CFD approach is proposed to speed up the DEM-CFD simulation without loss of accuracy. Pebble flow is simulated by a full 3D DEM, while the coolant flow field is calculated with a 2D CFD simulation by averaging variables along the annular direction in the cylindrical and annular geometries. Second, based on the slow motion of pebble flow, the impact of the coupling frequency on the computation accuracy and efficiency is
Geothermal energy control system and method
Matthews, Hugh B.
1977-01-01
A geothermal energy transfer and utilization system makes use of thermal energy stored in hot solute-bearing well water to generate super-heated steam from an injected flow of clean water; the super-heated steam is then used for operating a turbine-driven pump at the well bottom for pumping the hot solute-bearing water at high pressure and in liquid state to the earth's surface, where it is used by transfer of its heat to a closed-loop boiler-turbine-alternator combination for the generation of electrical or other power. Residual concentrated solute-bearing water is pumped back into the earth. The clean cooled water is regenerated at the surface-located system and is returned to the deep well pumping system also for lubrication of a novel bearing arrangement supporting the turbine-driven pump system. The bearing system employs liquid lubricated thrust and radial bearings with all bearing surfaces bathed in clean water serving as a lubricant and maintained under pressure to prevent entry into the bearings of contaminated geothermal fluid, an auxiliary thrust ball bearing arrangement comes into operation when starting or stopping the pumping system.
Aero-Hydro-Elastic Simulation Platform for Wave Energy Systems and floating Wind Turbines
DEFF Research Database (Denmark)
Kallesøe, Bjarne Skovmose
This report present results from the PSO project 2008-1-10092 entitled Aero-Hydro-Elastic Simulation Platform for Wave Energy Systems and floating Wind Turbines that deals with measurements, modelling and simulations of the world’s first combined wave and wind energy platform. The floating energy...
Comparison of gas dehydration methods based on energy ...
African Journals Online (AJOL)
Comparison of gas dehydration methods based on energy consumption. ... PROMOTING ACCESS TO AFRICAN RESEARCH ... This study compares three conventional methods of natural gas (Associated Natural Gas) dehydration to carry out ...
Experiences using DAKOTA stochastic expansion methods in computational simulations.
Energy Technology Data Exchange (ETDEWEB)
Templeton, Jeremy Alan; Ruthruff, Joseph R.
2012-01-01
Uncertainty quantification (UQ) methods bring rigorous statistical connections to the analysis of computational and experiment data, and provide a basis for probabilistically assessing margins associated with safety and reliability. The DAKOTA toolkit developed at Sandia National Laboratories implements a number of UQ methods, which are being increasingly adopted by modeling and simulation teams to facilitate these analyses. This report disseminates results as to the performance of DAKOTA's stochastic expansion methods for UQ on a representative application. Our results provide a number of insights that may be of interest to future users of these methods, including the behavior of the methods in estimating responses at varying probability levels, and the expansion levels for the methodologies that may be needed to achieve convergence.
A path method for finding energy barriers and minimum energy paths in complex micromagnetic systems
International Nuclear Information System (INIS)
Dittrich, R.; Schrefl, T.; Suess, D.; Scholz, W.; Forster, H.; Fidler, J.
2002-01-01
Minimum energy paths and energy barriers are calculated for complex micromagnetic systems. The method is based on the nudged elastic band method and uses finite-element techniques to represent granular structures. The method was found to be robust and fast for both simple test problems as well as for large systems such as patterned granular media. The method is used to estimate the energy barriers in CoCr-based perpendicular recording media
A modular method to handle multiple time-dependent quantities in Monte Carlo simulations
International Nuclear Information System (INIS)
Shin, J; Faddegon, B A; Perl, J; Schümann, J; Paganetti, H
2012-01-01
A general method for handling time-dependent quantities in Monte Carlo simulations was developed to make such simulations more accessible to the medical community for a wide range of applications in radiotherapy, including fluence and dose calculation. To describe time-dependent changes in the most general way, we developed a grammar of functions that we call ‘Time Features’. When a simulation quantity, such as the position of a geometrical object, an angle, a magnetic field, a current, etc, takes its value from a Time Feature, that quantity varies over time. The operation of time-dependent simulation was separated into distinct parts: the Sequence samples time values either sequentially at equal increments or randomly from a uniform distribution (allowing quantities to vary continuously in time), and then each time-dependent quantity is calculated according to its Time Feature. Due to this modular structure, time-dependent simulations, even in the presence of multiple time-dependent quantities, can be efficiently performed in a single simulation with any given time resolution. This approach has been implemented in TOPAS (TOol for PArticle Simulation), designed to make Monte Carlo simulations with Geant4 more accessible to both clinical and research physicists. To demonstrate the method, three clinical situations were simulated: a variable water column used to verify constancy of the Bragg peak of the Crocker Lab eye treatment facility of the University of California, the double-scattering treatment mode of the passive beam scattering system at Massachusetts General Hospital (MGH), where a spinning range modulator wheel accompanied by beam current modulation produces a spread-out Bragg peak, and the scanning mode at MGH, where time-dependent pulse shape, energy distribution and magnetic fields control Bragg peak positions. Results confirm the clinical applicability of the method. (paper)
Simulation of wing-body junction flows with hybrid RANS/LES methods
International Nuclear Information System (INIS)
Fu Song; Xiao Zhixiang; Chen Haixin; Zhang Yufei; Huang Jingbo
2007-01-01
In this paper, flows past two wing-body junctions, the Rood at zero angle of attack and NASA TN D-712 at 12.5 o angle of attack, are investigated with two Reynolds-Averaged Navier-Stokes (RANS) and large eddy simulation (LES) hybrid methods. One is detached eddy simulation (DES) and the other is delayed-DES, both are based on a weakly nonlinear two-equation k-ω model. While the RANS method can predict the mean flow behaviours reasonably accurately, its performance for the turbulent kinetic energy and shear stress, as compared with available experimental data, is not satisfactory. DES, through introducing a length scale in the dissipation terms of the turbulent kinetic energy equation, delivers flow separation, a vortex or the onset of vortex breakdown too early. DDES, with its delayed effect, shows a great improvement in flow structures and turbulence characteristics, and agrees well with measurements
Discrete Element Method Simulation of a Boulder Extraction From an Asteroid
Kulchitsky, Anton K.; Johnson, Jerome B.; Reeves, David M.; Wilkinson, Allen
2014-01-01
The force required to pull 7t and 40t polyhedral boulders from the surface of an asteroid is simulated using the discrete element method considering the effects of microgravity, regolith cohesion and boulder acceleration. The connection between particle surface energy and regolith cohesion is estimated by simulating a cohesion sample tearing test. An optimal constant acceleration is found where the peak net force from inertia and cohesion is a minimum. Peak pulling forces can be further reduced by using linear and quadratic acceleration functions with up to a 40% reduction in force for quadratic acceleration.
SUPERNOVA SIMULATIONS AND STRATEGIES FOR THE DARK ENERGY SURVEY
Energy Technology Data Exchange (ETDEWEB)
Bernstein, J. P.; Kuhlmann, S.; Biswas, R.; Kovacs, E.; Crane, I.; Hufford, T. [Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439 (United States); Kessler, R.; Frieman, J. A. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Aldering, G.; Kim, A. G.; Nugent, P. [E. O. Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); D' Andrea, C. B.; Nichol, R. C. [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth PO1 3FX (United Kingdom); Finley, D. A.; Marriner, J.; Reis, R. R. R. [Center for Particle Astrophysics, Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States); Jarvis, M. J. [Centre for Astrophysics, Science and Technology Research Institute, University of Hertfordshire, Hatfield, Herts AL10 9AB (United Kingdom); Mukherjee, P.; Parkinson, D. [Department of Physics and Astronomy, Pevensey 2 Building, University of Sussex, Falmer, Brighton BN1 9QH (United Kingdom); Sako, M. [Department of Physics and Astronomy, University of Pennsylvania, 203 South 33rd Street, Philadelphia, PA 19104 (United States); and others
2012-07-10
We present an analysis of supernova light curves simulated for the upcoming Dark Energy Survey (DES) supernova search. The simulations employ a code suite that generates and fits realistic light curves in order to obtain distance modulus/redshift pairs that are passed to a cosmology fitter. We investigated several different survey strategies including field selection, supernova selection biases, and photometric redshift measurements. Using the results of this study, we chose a 30 deg{sup 2} search area in the griz filter set. We forecast (1) that this survey will provide a homogeneous sample of up to 4000 Type Ia supernovae in the redshift range 0.05
SUPERNOVA SIMULATIONS AND STRATEGIES FOR THE DARK ENERGY SURVEY
International Nuclear Information System (INIS)
Bernstein, J. P.; Kuhlmann, S.; Biswas, R.; Kovacs, E.; Crane, I.; Hufford, T.; Kessler, R.; Frieman, J. A.; Aldering, G.; Kim, A. G.; Nugent, P.; D'Andrea, C. B.; Nichol, R. C.; Finley, D. A.; Marriner, J.; Reis, R. R. R.; Jarvis, M. J.; Mukherjee, P.; Parkinson, D.; Sako, M.
2012-01-01
We present an analysis of supernova light curves simulated for the upcoming Dark Energy Survey (DES) supernova search. The simulations employ a code suite that generates and fits realistic light curves in order to obtain distance modulus/redshift pairs that are passed to a cosmology fitter. We investigated several different survey strategies including field selection, supernova selection biases, and photometric redshift measurements. Using the results of this study, we chose a 30 deg 2 search area in the griz filter set. We forecast (1) that this survey will provide a homogeneous sample of up to 4000 Type Ia supernovae in the redshift range 0.05 < z < 1.2 and (2) that the increased red efficiency of the DES camera will significantly improve high-redshift color measurements. The redshift of each supernova with an identified host galaxy will be obtained from spectroscopic observations of the host. A supernova spectrum will be obtained for a subset of the sample, which will be utilized for control studies. In addition, we have investigated the use of combined photometric redshifts taking into account data from both the host and supernova. We have investigated and estimated the likely contamination from core-collapse supernovae based on photometric identification, and have found that a Type Ia supernova sample purity of up to 98% is obtainable given specific assumptions. Furthermore, we present systematic uncertainties due to sample purity, photometric calibration, dust extinction priors, filter-centroid shifts, and inter-calibration. We conclude by estimating the uncertainty on the cosmological parameters that will be measured from the DES supernova data.
Method II : The energy-momentum map
Broer, H.; Hoveijn, I.; Lunter, G.; Vegter, G.
2003-01-01
In this chapter we apply the energy–momentum map reduction method to the same class of systems as in Chap. 2, namely two degree-of-freedom systems with optional symmetry, near equilibrium and close to resonance. We calculate the tangent space and nondegeneracy conditions for the 1:2, 1:3 and 1:4
From fuel cells to batteries: Synergies, scales and simulation methods
Bessler, Wolfgang G.
2011-01-01
The recent years have shown a dynamic growth of battery research and development activities both in academia and industry, supported by large governmental funding initiatives throughout the world. A particular focus is being put on lithium-based battery technologies. This situation provides a stimulating environment for the fuel cell modeling community, as there are considerable synergies in the modeling and simulation methods for fuel cells and batteries. At the same time, batter...
A novel method for predicting the power outputs of wave energy converters
Wang, Yingguang
2018-03-01
This paper focuses on realistically predicting the power outputs of wave energy converters operating in shallow water nonlinear waves. A heaving two-body point absorber is utilized as a specific calculation example, and the generated power of the point absorber has been predicted by using a novel method (a nonlinear simulation method) that incorporates a second order random wave model into a nonlinear dynamic filter. It is demonstrated that the second order random wave model in this article can be utilized to generate irregular waves with realistic crest-trough asymmetries, and consequently, more accurate generated power can be predicted by subsequently solving the nonlinear dynamic filter equation with the nonlinearly simulated second order waves as inputs. The research findings demonstrate that the novel nonlinear simulation method in this article can be utilized as a robust tool for ocean engineers in their design, analysis and optimization of wave energy converters.
Application of subset simulation methods to dynamic fault tree analysis
International Nuclear Information System (INIS)
Liu Mengyun; Liu Jingquan; She Ding
2015-01-01
Although fault tree analysis has been implemented in the nuclear safety field over the past few decades, it was recently criticized for the inability to model the time-dependent behaviors. Several methods are proposed to overcome this disadvantage, and dynamic fault tree (DFT) has become one of the research highlights. By introducing additional dynamic gates, DFT is able to describe the dynamic behaviors like the replacement of spare components or the priority of failure events. Using Monte Carlo simulation (MCS) approach to solve DFT has obtained rising attention, because it can model the authentic behaviors of systems and avoid the limitations in the analytical method. In this paper, it provides an overview and MCS information for DFT analysis, including the sampling of basic events and the propagation rule for logic gates. When calculating rare-event probability, large amount of simulations in standard MCS are required. To improve the weakness, subset simulation (SS) approach is applied. Using the concept of conditional probability and Markov Chain Monte Carlo (MCMC) technique, the SS method is able to accelerate the efficiency of exploring the failure region. Two cases are tested to illustrate the performance of SS approach, and the numerical results suggest that it gives high efficiency when calculating complicated systems with small failure probabilities. (author)
A computer method for simulating the decay of radon daughters
International Nuclear Information System (INIS)
Hartley, B.M.
1988-01-01
The analytical equations representing the decay of a series of radioactive atoms through a number of daughter products are well known. These equations are for an idealized case in which the expectation value of the number of atoms which decay in a certain time can be represented by a smooth curve. The real curve of the total number of disintegrations from a radioactive species consists of a series of Heaviside step functions, with the steps occurring at the time of the disintegration. The disintegration of radioactive atoms is said to be random but this random behaviour is such that a single species forms an ensemble of which the times of disintegration give a geometric distribution. Numbers which have a geometric distribution can be generated by computer and can be used to simulate the decay of one or more radioactive species. A computer method is described for simulating such decay of radioactive atoms and this method is applied specifically to the decay of the short half life daughters of radon 222 and the emission of alpha particles from polonium 218 and polonium 214. Repeating the simulation of the decay a number of times provides a method for investigating the statistical uncertainty inherent in methods for measurement of exposure to radon daughters. This statistical uncertainty is difficult to investigate analytically since the time of decay of an atom of polonium 218 is not independent of the time of decay of subsequent polonium 214. The method is currently being used to investigate the statistical uncertainties of a number of commonly used methods for the counting of alpha particles from radon daughters and the calculations of exposure
Optimization Models and Methods Developed at the Energy Systems Institute
N.I. Voropai; V.I. Zorkaltsev
2013-01-01
The paper presents shortly some optimization models of energy system operation and expansion that have been created at the Energy Systems Institute of the Siberian Branch of the Russian Academy of Sciences. Consideration is given to the optimization models of energy development in Russia, a software package intended for analysis of power system reliability, and model of flow distribution in hydraulic systems. A general idea of the optimization methods developed at the Energy Systems Institute...
A novel iterative energy calibration method for composite germanium detectors
International Nuclear Information System (INIS)
Pattabiraman, N.S.; Chintalapudi, S.N.; Ghugre, S.S.
2004-01-01
An automatic method for energy calibration of the observed experimental spectrum has been developed. The method presented is based on an iterative algorithm and presents an efficient way to perform energy calibrations after establishing the weights of the calibration data. An application of this novel technique for data acquired using composite detectors in an in-beam γ-ray spectroscopy experiment is presented
A novel iterative energy calibration method for composite germanium detectors
Energy Technology Data Exchange (ETDEWEB)
Pattabiraman, N.S.; Chintalapudi, S.N.; Ghugre, S.S. E-mail: ssg@alpha.iuc.res.in
2004-07-01
An automatic method for energy calibration of the observed experimental spectrum has been developed. The method presented is based on an iterative algorithm and presents an efficient way to perform energy calibrations after establishing the weights of the calibration data. An application of this novel technique for data acquired using composite detectors in an in-beam {gamma}-ray spectroscopy experiment is presented.
Landsgesell, Jonas; Holm, Christian; Smiatek, Jens
2017-02-14
We present a novel method for the study of weak polyelectrolytes and general acid-base reactions in molecular dynamics and Monte Carlo simulations. The approach combines the advantages of the reaction ensemble and the Wang-Landau sampling method. Deprotonation and protonation reactions are simulated explicitly with the help of the reaction ensemble method, while the accurate sampling of the corresponding phase space is achieved by the Wang-Landau approach. The combination of both techniques provides a sufficient statistical accuracy such that meaningful estimates for the density of states and the partition sum can be obtained. With regard to these estimates, several thermodynamic observables like the heat capacity or reaction free energies can be calculated. We demonstrate that the computation times for the calculation of titration curves with a high statistical accuracy can be significantly decreased when compared to the original reaction ensemble method. The applicability of our approach is validated by the study of weak polyelectrolytes and their thermodynamic properties.
TMCC: a transient three-dimensional neutron transport code by the direct simulation method - 222
International Nuclear Information System (INIS)
Shen, H.; Li, Z.; Wang, K.; Yu, G.
2010-01-01
A direct simulation method (DSM) is applied to solve the transient three-dimensional neutron transport problems. DSM is based on the Monte Carlo method, and can be considered as an application of the Monte Carlo method in the specific type of problems. In this work, the transient neutronics problem is solved by simulating the dynamic behaviors of neutrons and precursors of delayed neutrons during the transient process. DSM gets rid of various approximations which are always necessary to other methods, so it is precise and flexible in the requirement of geometric configurations, material compositions and energy spectrum. In this paper, the theory of DSM is introduced first, and the numerical results obtained with the new transient analysis code, named TMCC (Transient Monte Carlo Code), are presented. (authors)
Impedance adaptation methods of the piezoelectric energy harvesting
Kim, Hyeoungwoo
factor. This characteristic is useful for a small force vibration source which has a high displacement such as human's activities. An experimental setup was used to apply the same conditions as a vibrating car engine. The experiment was done with a cymbal transducer which has 29 mm PZT diameter, 1mm PZT thickness, and 0.4mm endcap operating under force of 70 N in the frequency range of 10--200 Hz. It was found that the generated power was increased and the output impedance was decreased with a higher frequency of vibration source at a constant force. The experimental results were found to be in agreement with the analytical results from the model using the equivalent circuit. In addition, the FEM simulation (ATILA) was employed to optimize the dimensions of cymbal transducer such as endcap thickness and PZT thickness. Finally, the electrical impedance matching method used to increase the electrical to electrical energy transfer for some applications was discussed. To match the output impedance, two methods were employed: one is changing capacitance of transducer by size effect and multilayered ceramics, and another one is developing an energy harvesting circuit which consumes low electrical power and maximizes the output transferred to the intended load. The fabricated multilayered ceramics which has 10, 100 mum thick, layers yielded 10 times higher output current for 40 times reduced output load. Also the electrical output power was double. A DC-DC buck converter which has 78% efficiency was fabricated to transfer the accumulated electrical energy to the low output load without consuming more than 5 mW of power itself. In this DC-DC converter, most of the power was consumed by the gate drive which was required for PWM switching. To reduce the power consumption of the gate drive, the switching frequency was fixed at 1 kHz with optimal duty cycle around 1˜5%. Also the dependence of the inductance (L) in the DC-DC converter was investigated and optimized to increase the
Energy based methods for determining elastic plastic fracture
International Nuclear Information System (INIS)
Witt, F.J.
1979-01-01
Several methods are currently in use or under study for calculating various conditions of fracturing for varying degrees of plasticity. Among these are innovations on the J-integral concept, crack opening displacement or angle, the two parameter concept and the equivalent energy method. Methods involving crack arrest and ductile tearing also fall in this category. Each of these methods have many salient points and some efforts are underway to establish the underlying relationship between them. In this paper, the current research directions of J-integral and equivalent energy methodologies are reviewed with a broader discussion presented for the equivalent energy methodology. The fundamental basis of equivalent energy methodology rests with the volumetric energy ratio. For fractures governed by linear elastic fracture mechanics, the volumetric energy ratio is independent of flaw size and geometry and depends only on the scale factor between model and prototype and temperature. The behavioral aspects of the volumetric energy ratios have been investigated throughout the temperature range from brittle fracture to fully ductile fracture. For five different specimen and structural configurations it has been shown experimentally that the volumetric energy ratio retains its basic properties. That is, the volumetric energy ratio while changing in actual value, maintains its independence of geometry and flaw size while retaining a unique dependence on scale factor and temperature. This property interpreted in terms of fracture mechanics leads to the equivalent energy method. (orig.)
Chowdhury, Md Mukul
With the increased practice of modularization and prefabrication, the construction industry gained the benefits of quality management, improved completion time, reduced site disruption and vehicular traffic, and improved overall safety and security. Whereas industrialized construction methods, such as modular and manufactured buildings, have evolved over decades, core techniques used in prefabrication plants vary only slightly from those employed in traditional site-built construction. With a focus on energy and cost efficient modular construction, this research presents the development of a simulation, measurement and optimization system for energy consumption in the manufacturing process of modular construction. The system is based on Lean Six Sigma principles and loosely coupled system operation to identify the non-value adding tasks and possible causes of low energy efficiency. The proposed system will also include visualization functions for demonstration of energy consumption in modular construction. The benefits of implementing this system include a reduction in the energy consumption in production cost, decrease of energy cost in the production of lean-modular construction, and increase profit. In addition, the visualization functions will provide detailed information about energy efficiency and operation flexibility in modular construction. A case study is presented to validate the reliability of the system.
Atmosphere Re-Entry Simulation Using Direct Simulation Monte Carlo (DSMC Method
Directory of Open Access Journals (Sweden)
Francesco Pellicani
2016-05-01
Full Text Available Hypersonic re-entry vehicles aerothermodynamic investigations provide fundamental information to other important disciplines like materials and structures, assisting the development of thermal protection systems (TPS efficient and with a low weight. In the transitional flow regime, where thermal and chemical equilibrium is almost absent, a new numerical method for such studies has been introduced, the direct simulation Monte Carlo (DSMC numerical technique. The acceptance and applicability of the DSMC method have increased significantly in the 50 years since its invention thanks to the increase in computer speed and to the parallel computing. Anyway, further verification and validation efforts are needed to lead to its greater acceptance. In this study, the Monte Carlo simulator OpenFOAM and Sparta have been studied and benchmarked against numerical and theoretical data for inert and chemically reactive flows and the same will be done against experimental data in the near future. The results show the validity of the data found with the DSMC. The best setting of the fundamental parameters used by a DSMC simulator are presented for each software and they are compared with the guidelines deriving from the theory behind the Monte Carlo method. In particular, the number of particles per cell was found to be the most relevant parameter to achieve valid and optimized results. It is shown how a simulation with a mean value of one particle per cell gives sufficiently good results with very low computational resources. This achievement aims to reconsider the correct investigation method in the transitional regime where both the direct simulation Monte Carlo (DSMC and the computational fluid-dynamics (CFD can work, but with a different computational effort.
A particle finite element method for machining simulations
Sabel, Matthias; Sator, Christian; Müller, Ralf
2014-07-01
The particle finite element method (PFEM) appears to be a convenient technique for machining simulations, since the geometry and topology of the problem can undergo severe changes. In this work, a short outline of the PFEM-algorithm is given, which is followed by a detailed description of the involved operations. The -shape method, which is used to track the topology, is explained and tested by a simple example. Also the kinematics and a suitable finite element formulation are introduced. To validate the method simple settings without topological changes are considered and compared to the standard finite element method for large deformations. To examine the performance of the method, when dealing with separating material, a tensile loading is applied to a notched plate. This investigation includes a numerical analysis of the different meshing parameters, and the numerical convergence is studied. With regard to the cutting simulation it is found that only a sufficiently large number of particles (and thus a rather fine finite element discretisation) leads to converged results of process parameters, such as the cutting force.
Transport calculation of medium-energy protons and neutrons by Monte Carlo method
International Nuclear Information System (INIS)
Ban, Syuuichi; Hirayama, Hideo; Katoh, Kazuaki.
1978-09-01
A Monte Carlo transport code, ARIES, has been developed for protons and neutrons at medium energy (25 -- 500 MeV). Nuclear data provided by R.G. Alsmiller, Jr. were used for the calculation. To simulate the cascade development in the medium, each generation was represented by a single weighted particle and an average number of emitted particles was used as the weight. Neutron fluxes were stored by the collisions density method. The cutoff energy was set to 25 MeV. Neutrons below the cutoff were stored to be used as the source for the low energy neutron transport calculation upon the discrete ordinates method. Then transport calculations were performed for both low energy neutrons (thermal -- 25 MeV) and secondary gamma-rays. Energy spectra of emitted neutrons were calculated and compared with those of published experimental and calculated results. The agreement was good for the incident particles of energy between 100 and 500 MeV. (author)
Multigrid Methods for Fully Implicit Oil Reservoir Simulation
Molenaar, J.
1996-01-01
In this paper we consider the simultaneous flow of oil and water in reservoir rock. This displacement process is modeled by two basic equations: the material balance or continuity equations and the equation of motion (Darcy's law). For the numerical solution of this system of nonlinear partial differential equations there are two approaches: the fully implicit or simultaneous solution method and the sequential solution method. In the sequential solution method the system of partial differential equations is manipulated to give an elliptic pressure equation and a hyperbolic (or parabolic) saturation equation. In the IMPES approach the pressure equation is first solved, using values for the saturation from the previous time level. Next the saturations are updated by some explicit time stepping method; this implies that the method is only conditionally stable. For the numerical solution of the linear, elliptic pressure equation multigrid methods have become an accepted technique. On the other hand, the fully implicit method is unconditionally stable, but it has the disadvantage that in every time step a large system of nonlinear algebraic equations has to be solved. The most time-consuming part of any fully implicit reservoir simulator is the solution of this large system of equations. Usually this is done by Newton's method. The resulting systems of linear equations are then either solved by a direct method or by some conjugate gradient type method. In this paper we consider the possibility of applying multigrid methods for the iterative solution of the systems of nonlinear equations. There are two ways of using multigrid for this job: either we use a nonlinear multigrid method or we use a linear multigrid method to deal with the linear systems that arise in Newton's method. So far only a few authors have reported on the use of multigrid methods for fully implicit simulations. Two-level FAS algorithm is presented for the black-oil equations, and linear multigrid for
The effect of interatomic potential in molecular dynamics simulation of low energy ion implantation
International Nuclear Information System (INIS)
Chan, H.Y.; Nordlund, K.; Peltola, J.; Gossmann, H.-J.L.; Ma, N.L.; Srinivasan, M.P.; Benistant, F.; Chan, Lap
2005-01-01
Being able to accurately predict dopant profiles at sub-keV implant energies is critical for the microelectronic industry. Molecular Dynamics (MD), with its capability to account for multiple interactions as energy lowers, is an increasingly popular simulation method. We report our work on sub-keV implantation using MD and investigate the effect of different interatomic potentials on the range profiles. As an approximation, only pair potentials are considered in this work. Density Functional Theory (DFT) is used to calculate the pair potentials for a wide range of dopants (B, C, N, F, Si, P, Ga, Ge, As, In and Sb) in single crystalline silicon. A commonly used repulsive potential is also included in the study. Importance of the repulsive and attractive regions of the potential has been investigated with different elements and we show that a potential depicting the right attractive forces is especially important for heavy elements at low energies
International Nuclear Information System (INIS)
Li, Gang; Li, Xiao-Sen; Li, Bo; Wang, Yi
2014-01-01
The combination forms of the hydrate dissociation methods in different well systems are divided into 6 main patterns. Dissociation processes of methane hydrate in porous media using the inverted five-spot water flooding method (Pattern 4) are investigated by the experimental observation and numerical simulation. In situ methane hydrate is synthesized in the Cubic Hydrate Simulator (CHS), a 5.832-L cubic reactor. A center vertical well is used as the hot water injection well, while the four vertical wells at the corner are the gas and water production wells. The gas production begins simultaneously with the hot water injection, while after approximately 20 min of compression, the water begins to be produced. One of the common characteristics of the inverted five-spot water flooding method is that both the gas and water production rates decrease with the reduction of the hydrate dissociation rate. The evaluation of the energy efficiency ratio might indicate the inverted five-spot water flooding as a promising gas producing method from the hydrate reservoir. - Highlights: • A three-dimensional 5.8-L cubic pressure vessel is developed. • Gas production of hydrate using inverted five-spot flooding method is studied. • Water/gas production rate and energy efficiency ratio are evaluated. • Temperature distributions of numerical simulation and experiment agree well. • Hydrate dissociation process is a moving boundary problem in this study
Research on Matching Method of Power Supply Parameters for Dual Energy Source Electric Vehicles
Jiang, Q.; Luo, M. J.; Zhang, S. K.; Liao, M. W.
2018-03-01
A new type of power source is proposed, which is based on the traffic signal matching method of the dual energy source power supply composed of the batteries and the supercapacitors. First, analyzing the power characteristics is required to meet the excellent dynamic characteristics of EV, studying the energy characteristics is required to meet the mileage requirements and researching the physical boundary characteristics is required to meet the physical conditions of the power supply. Secondly, the parameter matching design with the highest energy efficiency is adopted to select the optimal parameter group with the method of matching deviation. Finally, the simulation analysis of the vehicle is carried out in MATLABSimulink, The mileage and energy efficiency of dual energy sources are analyzed in different parameter models, and the rationality of the matching method is verified.
Method to deduce the energy spectrum by the Pierre Auger Observatory
Energy Technology Data Exchange (ETDEWEB)
Maris, I.; Roth, M.; Schmidt, T.; Schuessler, F.; Unger, M. [Univ. Karlsruhe (Germany); Bluemer, J. [Univ. Karlsruhe (Germany); Forschungszentrum Karlsruhe (Germany)
2007-07-01
Taken into account the great advantage of having a hybrid detector it has been developed a method, simulation independent, to determine the energy of the comic rays recorded by the surface detector of the Pierre Auger Observatory. The method assumes that the cosmic ray flux has the same distribution in zenith angle for all energy ranges. Therefore one can relate the calorimetric measurement of the fluorescence detector of the CR energy with a SD quantity, e.g. shower size at 1000m distance from the core, corrected for the different attenuations in the atmosphere. The method of measuring and calibrating the primary energy and the influence of reconstruction uncertainties on the energy spectrum are presented. (orig.)
Radon movement simulation in overburden by the 'Scattered Packet Method'
International Nuclear Information System (INIS)
Marah, H.; Sabir, A.; Hlou, L.; Tayebi, M.
1998-01-01
The analysis of Radon ( 222 Rn) movement in overburden needs the resolution of the General Equation of Transport in porous medium, involving diffusion and convection. Generally this equation was derived and solved analytically. The 'Scattered Packed Method' is a recent mathematical method of resolution, initially developed for the electrons movements in the semiconductors studies. In this paper, we have adapted this method to simulate radon emanation in porous medium. The keys parameters are the radon concentration at the source, the diffusion coefficient, and the geometry. To show the efficiency of this method, several cases of increasing complexity are considered. This model allows to follow the migration, in the time and space, of radon produced as a function of the characteristics of the studied site. Forty soil radon measurements were taken from a North Moroccan fault. Forward modeling of the radon anomalies produces satisfactory fits of the observed data and allows the overburden thickness determination. (author)
Chassin, David P [Pasco, WA; Donnelly, Matthew K [Kennewick, WA; Dagle, Jeffery E [Richland, WA
2011-12-06
Electrical power distribution control methods, electrical energy demand monitoring methods, and power management devices are described. In one aspect, an electrical power distribution control method includes providing electrical energy from an electrical power distribution system, applying the electrical energy to a load, providing a plurality of different values for a threshold at a plurality of moments in time and corresponding to an electrical characteristic of the electrical energy, and adjusting an amount of the electrical energy applied to the load responsive to an electrical characteristic of the electrical energy triggering one of the values of the threshold at the respective moment in time.
External individual monitoring: experiments and simulations using Monte Carlo Method
International Nuclear Information System (INIS)
Guimaraes, Carla da Costa
2005-01-01
In this work, we have evaluated the possibility of applying the Monte Carlo simulation technique in photon dosimetry of external individual monitoring. The GEANT4 toolkit was employed to simulate experiments with radiation monitors containing TLD-100 and CaF 2 :NaCl thermoluminescent detectors. As a first step, X ray spectra were generated impinging electrons on a tungsten target. Then, the produced photon beam was filtered in a beryllium window and additional filters to obtain the radiation with desired qualities. This procedure, used to simulate radiation fields produced by a X ray tube, was validated by comparing characteristics such as half value layer, which was also experimentally measured, mean photon energy and the spectral resolution of simulated spectra with that of reference spectra established by international standards. In the construction of thermoluminescent dosimeter, two approaches for improvements have. been introduced. The first one was the inclusion of 6% of air in the composition of the CaF 2 :NaCl detector due to the difference between measured and calculated values of its density. Also, comparison between simulated and experimental results showed that the self-attenuation of emitted light in the readout process of the fluorite dosimeter must be taken into account. Then, in the second approach, the light attenuation coefficient of CaF 2 :NaCl compound estimated by simulation to be 2,20(25) mm -1 was introduced. Conversion coefficients C p from air kerma to personal dose equivalent were calculated using a slab water phantom with polymethyl-metacrilate (PMMA) walls, for reference narrow and wide X ray spectrum series [ISO 4037-1], and also for the wide spectra implanted and used in routine at Laboratorio de Dosimetria. Simulations of backscattered radiations by PMMA slab water phantom and slab phantom of ICRU tissue-equivalent material produced very similar results. Therefore, the PMMA slab water phantom that can be easily constructed with low
An Energy Efficiency Evaluation Method Based on Energy Baseline for Chemical Industry
Directory of Open Access Journals (Sweden)
Dong-mei Yao
2016-01-01
Full Text Available According to the requirements and structure of ISO 50001 energy management system, this study proposes an energy efficiency evaluation method based on energy baseline for chemical industry. Using this method, the energy plan implementation effect in the processes of chemical production can be evaluated quantitatively, and evidences for system fault diagnosis can be provided. This method establishes the energy baseline models which can meet the demand of the different kinds of production processes and gives the general solving method of each kind of model according to the production data. Then the energy plan implementation effect can be evaluated and also whether the system is running normally can be determined through the baseline model. Finally, this method is used on cracked gas compressor unit of ethylene plant in some petrochemical enterprise; it can be proven that this method is correct and practical.
International Nuclear Information System (INIS)
Berthiau, G.
1995-10-01
The circuit design problem consists in determining acceptable parameter values (resistors, capacitors, transistors geometries ...) which allow the circuit to meet various user given operational criteria (DC consumption, AC bandwidth, transient times ...). This task is equivalent to a multidimensional and/or multi objective optimization problem: n-variables functions have to be minimized in an hyper-rectangular domain ; equality constraints can be eventually specified. A similar problem consists in fitting component models. In this way, the optimization variables are the model parameters and one aims at minimizing a cost function built on the error between the model response and the data measured on the component. The chosen optimization method for this kind of problem is the simulated annealing method. This method, provided by the combinatorial optimization domain, has been adapted and compared with other global optimization methods for the continuous variables problems. An efficient strategy of variables discretization and a set of complementary stopping criteria have been proposed. The different parameters of the method have been adjusted with analytical functions of which minima are known, classically used in the literature. Our simulated annealing algorithm has been coupled with an open electrical simulator SPICE-PAC of which the modular structure allows the chaining of simulations required by the circuit optimization process. We proposed, for high-dimensional problems, a partitioning technique which ensures proportionality between CPU-time and variables number. To compare our method with others, we have adapted three other methods coming from combinatorial optimization domain - the threshold method, a genetic algorithm and the Tabu search method - The tests have been performed on the same set of test functions and the results allow a first comparison between these methods applied to continuous optimization variables. Finally, our simulated annealing program
International Nuclear Information System (INIS)
Hamilton, S.; Veselka, T.D.; Cirillo, R.R.
1991-01-01
Global warming control strategies which mandate stringent caps on emissions of greenhouse forcing gases can substantially alter a country's demand, production, and imports of energy products. Although there is a large degree of uncertainty when attempting to estimate the potential impact of these strategies, insights into the problem can be acquired through computer model simulations. This paper presents one method of structuring a general equilibrium model, the ENergy and Power Evaluation Program/Global Climate Change (ENPEP/GCC), to simulate changes in a country's energy supply and demand balance in response to global warming control strategies. The equilibrium model presented in this study is based on the principle of decomposition, whereby a large complex problem is divided into a number of smaller submodules. Submodules simulate energy activities and conversion processes such as electricity production. These submodules are linked together to form an energy supply and demand network. Linkages identify energy and fuel flows among various activities. Since global warming control strategies can have wide reaching effects, a complex network was constructed. The network represents all energy production, conversion, transportation, distribution, and utilization activities. The structure of the network depicts interdependencies within and across economic sectors and was constructed such that energy prices and demand responses can be simulated. Global warming control alternatives represented in the network include: (1) conservation measures through increased efficiency; and (2) substitution of fuels that have high greenhouse gas emission rates with fuels that have lower emission rates. 6 refs., 4 figs., 4 tabs
Energy storage cell impedance measuring apparatus, methods and related systems
Morrison, John L.; Morrison, William H.; Christophersen, Jon P.
2017-12-26
Energy storage cell impedance testing devices, circuits, and related methods are disclosed. An energy storage cell impedance measuring device includes a sum of sinusoids (SOS) current excitation circuit including differential current sources configured to isolate a ground terminal of the differential current sources from a positive terminal and a negative terminal of an energy storage cell. A method includes applying an SOS signal comprising a sum of sinusoidal current signals to the energy storage cell with the SOS current excitation circuit, each of the sinusoidal current signals oscillating at a different one of a plurality of different frequencies. The method also includes measuring an electrical signal at a positive terminal and a negative terminal of the energy storage cell, and computing an impedance of the energy storage cell at each of the plurality of different frequencies using the measured electrical signal.
Numerical method for IR background and clutter simulation
Quaranta, Carlo; Daniele, Gina; Balzarotti, Giorgio
1997-06-01
The paper describes a fast and accurate algorithm of IR background noise and clutter generation for application in scene simulations. The process is based on the hypothesis that background might be modeled as a statistical process where amplitude of signal obeys to the Gaussian distribution rule and zones of the same scene meet a correlation function with exponential form. The algorithm allows to provide an accurate mathematical approximation of the model and also an excellent fidelity with reality, that appears from a comparison with images from IR sensors. The proposed method shows advantages with respect to methods based on the filtering of white noise in time or frequency domain as it requires a limited number of computation and, furthermore, it is more accurate than the quasi random processes. The background generation starts from a reticule of few points and by means of growing rules the process is extended to the whole scene of required dimension and resolution. The statistical property of the model are properly maintained in the simulation process. The paper gives specific attention to the mathematical aspects of the algorithm and provides a number of simulations and comparisons with real scenes.
Viscoelastic Earthquake Cycle Simulation with Memory Variable Method
Hirahara, K.; Ohtani, M.
2017-12-01
There have so far been no EQ (earthquake) cycle simulations, based on RSF (rate and state friction) laws, in viscoelastic media, except for Kato (2002), who simulated cycles on a 2-D vertical strike-slip fault, and showed nearly the same cycles as those in elastic cases. The viscoelasticity could, however, give more effects on large dip-slip EQ cycles. In a boundary element approach, stress is calculated using a hereditary integral of stress relaxation function and slip deficit rate, where we need the past slip rates, leading to huge computational costs. This is a cause for almost no simulations in viscoelastic media. We have investigated the memory variable method utilized in numerical computation of wave propagation in dissipative media (e.g., Moczo and Kristek, 2005). In this method, introducing memory variables satisfying 1st order differential equations, we need no hereditary integrals in stress calculation and the computational costs are the same order of those in elastic cases. Further, Hirahara et al. (2012) developed the iterative memory variable method, referring to Taylor et al. (1970), in EQ cycle simulations in linear viscoelastic media. In this presentation, first, we introduce our method in EQ cycle simulations and show the effect of the linear viscoelasticity on stick-slip cycles in a 1-DOF block-SLS (standard linear solid) model, where the elastic spring of the traditional block-spring model is replaced by SLS element and we pull, in a constant rate, the block obeying RSF law. In this model, the memory variable stands for the displacement of the dash-pot in SLS element. The use of smaller viscosity reduces the recurrence time to a minimum value. The smaller viscosity means the smaller relaxation time, which makes the stress recovery quicker, leading to the smaller recurrence time. Second, we show EQ cycles on a 2-D dip-slip fault with the dip angel of 20 degrees in an elastic layer with thickness of 40 km overriding a Maxwell viscoelastic half
Simulation study on unfolding methods for diagnostic X-rays and mixed gamma rays
International Nuclear Information System (INIS)
Hashimoto, Makoto; Ohtaka, Masahiko; Ara, Kuniaki; Kanno, Ikuo; Imamura, Ryo; Mikami, Kenta; Nomiya, Seiichiro; Onabe, Hideaki
2009-01-01
A photon detector operating in current mode that can sense X-ray energy distribution has been reported. This detector consists of a row of several segment detectors. The energy distribution is derived using an unfolding technique. In this paper, comparisons of the unfolding techniques among error reduction, spectrum surveillance, and neural network methods are discussed through simulation studies on the detection of diagnostic X-rays and gamma rays emitted by a mixture of 137 Cs and 60 Co. For diagnostic X-ray measurement, the spectrum surveillance and neural network methods appeared promising, while the error reduction method yielded poor results. However, in the case of measuring mixtures of gamma rays, the error reduction method was both sufficient and effective. (author)
Amyloid oligomer structure characterization from simulations: A general method
Energy Technology Data Exchange (ETDEWEB)
Nguyen, Phuong H., E-mail: phuong.nguyen@ibpc.fr [Laboratoire de Biochimie Théorique, UPR 9080, CNRS Université Denis Diderot, Sorbonne Paris Cité IBPC, 13 rue Pierre et Marie Curie, 75005 Paris (France); Li, Mai Suan [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Derreumaux, Philippe, E-mail: philippe.derreumaux@ibpc.fr [Laboratoire de Biochimie Théorique, UPR 9080, CNRS Université Denis Diderot, Sorbonne Paris Cité IBPC, 13 rue Pierre et Marie Curie, 75005 Paris (France); Institut Universitaire de France, 103 Bvd Saint-Germain, 75005 Paris (France)
2014-03-07
Amyloid oligomers and plaques are composed of multiple chemically identical proteins. Therefore, one of the first fundamental problems in the characterization of structures from simulations is the treatment of the degeneracy, i.e., the permutation of the molecules. Second, the intramolecular and intermolecular degrees of freedom of the various molecules must be taken into account. Currently, the well-known dihedral principal component analysis method only considers the intramolecular degrees of freedom, and other methods employing collective variables can only describe intermolecular degrees of freedom at the global level. With this in mind, we propose a general method that identifies all the structures accurately. The basis idea is that the intramolecular and intermolecular states are described in terms of combinations of single-molecule and double-molecule states, respectively, and the overall structures of oligomers are the product basis of the intramolecular and intermolecular states. This way, the degeneracy is automatically avoided. The method is illustrated on the conformational ensemble of the tetramer of the Alzheimer's peptide Aβ{sub 9−40}, resulting from two atomistic molecular dynamics simulations in explicit solvent, each of 200 ns, starting from two distinct structures.
Limitations in simulator time-based human reliability analysis methods
International Nuclear Information System (INIS)
Wreathall, J.
1989-01-01
Developments in human reliability analysis (HRA) methods have evolved slowly. Current methods are little changed from those of almost a decade ago, particularly in the use of time-reliability relationships. While these methods were suitable as an interim step, the time (and the need) has come to specify the next evolution of HRA methods. As with any performance-oriented data source, power plant simulator data have no direct connection to HRA models. Errors reported in data are normal deficiencies observed in human performance; failures are events modeled in probabilistic risk assessments (PRAs). Not all errors cause failures; not all failures are caused by errors. Second, the times at which actions are taken provide no measure of the likelihood of failures to act correctly within an accident scenario. Inferences can be made about human reliability, but they must be made with great care. Specific limitations are discussed. Simulator performance data are useful in providing qualitative evidence of the variety of error types and their potential influences on operating systems. More work is required to combine recent developments in the psychology of error with the qualitative data collected at stimulators. Until data become openly available, however, such an advance will not be practical
SIMULATION OF THE SYSTEMS WITH RENEWABLE ENERGY SOURCES USING HOMER SOFTWARE
Directory of Open Access Journals (Sweden)
FIRINCĂ S.D.
2015-12-01
Full Text Available This paper simulates by using the Homer software, distributed energy systems with capacity below 1 MW. Among the renewable energy sources are used wind and solar energy. For photovoltaic panels, we are considering two situations: fixed panels, oriented at 45 ° and panels with tracking system with two axis. Simulation results contain information regarding operation hours of the system throughout the year, energy produced from the renewable energy sources, energy consumption for the load, and excess of electrical energy. The Homer software also allows an economic analysis of these systems.
Thermal energy storage apparatus, controllers and thermal energy storage control methods
Hammerstrom, Donald J.
2016-05-03
Thermal energy storage apparatus, controllers and thermal energy storage control methods are described. According to one aspect, a thermal energy storage apparatus controller includes processing circuitry configured to access first information which is indicative of surpluses and deficiencies of electrical energy upon an electrical power system at a plurality of moments in time, access second information which is indicative of temperature of a thermal energy storage medium at a plurality of moments in time, and use the first and second information to control an amount of electrical energy which is utilized by a heating element to heat the thermal energy storage medium at a plurality of moments in time.
Household energy studies: the gap between theory and method
Energy Technology Data Exchange (ETDEWEB)
Crosbie, T.
2006-09-15
At the level of theory it is now widely accepted that energy consumption patterns are a complex technical and socio-cultural phenomenon and to understand this phenomenon, it must be viewed from both engineering and social science perspectives. However, the methodological approaches taken in household energy studies lag behind the theoretical advances made in the last ten or fifteen years. The quantitative research methods traditionally used within the fields of building science, economics, and psychology continue to dominate household energy studies, while the qualitative ethnographic approaches to examining social and cultural phenomena traditionally used within anthropology and sociology are most frequently overlooked. This paper offers a critical review of the research methods used in household energy studies which illustrates the scope and limitations of both qualitative and quantitative research methods in this area of study. In doing so it demonstrates that qualitative research methods are essential to designing effective energy efficiency interventions. [Author].
Hardware-in-the-loop grid simulator system and method
Fox, John Curtiss; Collins, Edward Randolph; Rigas, Nikolaos
2017-05-16
A hardware-in-the-loop (HIL) electrical grid simulation system and method that combines a reactive divider with a variable frequency converter to better mimic and control expected and unexpected parameters in an electrical grid. The invention provides grid simulation in a manner to allow improved testing of variable power generators, such as wind turbines, and their operation once interconnected with an electrical grid in multiple countries. The system further comprises an improved variable fault reactance (reactive divider) capable of providing a variable fault reactance power output to control a voltage profile, therein creating an arbitrary recovery voltage. The system further comprises an improved isolation transformer designed to isolate zero-sequence current from either a primary or secondary winding in a transformer or pass the zero-sequence current from a primary to a secondary winding.
Jakobtorweihen, S.; Zuniga, A. Chaides; Ingram, T.; Gerlach, T.; Keil, F. J.; Smirnova, I.
2014-07-01
Quantitative predictions of biomembrane/water partition coefficients are important, as they are a key property in pharmaceutical applications and toxicological studies. Molecular dynamics (MD) simulations are used to calculate free energy profiles for different solutes in lipid bilayers. How to calculate partition coefficients from these profiles is discussed in detail and different definitions of partition coefficients are compared. Importantly, it is shown that the calculated coefficients are in quantitative agreement with experimental results. Furthermore, we compare free energy profiles from MD simulations to profiles obtained by the recent method COSMOmic, which is an extension of the conductor-like screening model for realistic solvation to micelles and biomembranes. The free energy profiles from these molecular methods are in good agreement. Additionally, solute orientations calculated with MD and COSMOmic are compared and again a good agreement is found. Four different solutes are investigated in detail: 4-ethylphenol, propanol, 5-phenylvaleric acid, and dibenz[a,h]anthracene, whereby the latter belongs to the class of polycyclic aromatic hydrocarbons. The convergence of the free energy profiles from biased MD simulations is discussed and the results are shown to be comparable to equilibrium MD simulations. For 5-phenylvaleric acid the influence of the carboxyl group dihedral angle on free energy profiles is analyzed with MD simulations.
International Nuclear Information System (INIS)
Jakobtorweihen, S.; Ingram, T.; Gerlach, T.; Smirnova, I.; Zuniga, A. Chaides; Keil, F. J.
2014-01-01
Quantitative predictions of biomembrane/water partition coefficients are important, as they are a key property in pharmaceutical applications and toxicological studies. Molecular dynamics (MD) simulations are used to calculate free energy profiles for different solutes in lipid bilayers. How to calculate partition coefficients from these profiles is discussed in detail and different definitions of partition coefficients are compared. Importantly, it is shown that the calculated coefficients are in quantitative agreement with experimental results. Furthermore, we compare free energy profiles from MD simulations to profiles obtained by the recent method COSMOmic, which is an extension of the conductor-like screening model for realistic solvation to micelles and biomembranes. The free energy profiles from these molecular methods are in good agreement. Additionally, solute orientations calculated with MD and COSMOmic are compared and again a good agreement is found. Four different solutes are investigated in detail: 4-ethylphenol, propanol, 5-phenylvaleric acid, and dibenz[a,h]anthracene, whereby the latter belongs to the class of polycyclic aromatic hydrocarbons. The convergence of the free energy profiles from biased MD simulations is discussed and the results are shown to be comparable to equilibrium MD simulations. For 5-phenylvaleric acid the influence of the carboxyl group dihedral angle on free energy profiles is analyzed with MD simulations
Target injection methods for inertial fusion energy
International Nuclear Information System (INIS)
Petzoldt, R.W.; Moir, R.W.
1994-06-01
We have studied four methods to inject IFE targets: the gas gun, electrostatic accelerator, induction accelerator, and rail gun. We recommend a gas gun for indirect drive targets because they can support a gas pressure load on one end and can slide along the gun barrel without damage. With the gas gun, the amount of gas required for each target (about 10 to 100 mg) is acceptable; for other types of targets, a sabot would be necessary. A cam and poppet valve arrangement is recommended for gas flow control. An electrostatic accelerator is attractive for use with lightweight spherical direct drive targets. Since there is no physical contact between the target and the injector, there will be no wear of either component during the injection process. An induction accelerator has an advantage of no electrical contact between the target and the injector. Physical contact is not even necessary, so the wear should be minimal. It requires a cylindrical conductive target sleeve which is a substantial added mass. A rail gun is a simpler device than an electrostatic accelerator or induction accelerator. It requires electrical contact between the target and the rails and may have a significant wear rate. The wear in a vacuum could be reduced by use of a solid lubricant such as MoS 2 . The total required accuracy of target injection, tracking and beam pointing of ±0.4 mm appears achievable but will require development and experimental verification
Strategic Plan for Nuclear Energy -- Knowledge Base for Advanced Modeling and Simulation (NE-KAMS)
Energy Technology Data Exchange (ETDEWEB)
Kimberlyn C. Mousseau
2011-10-01
The Nuclear Energy Computational Fluid Dynamics Advanced Modeling and Simulation (NE-CAMS) system is being developed at the Idaho National Laboratory (INL) in collaboration with Bettis Laboratory, Sandia National Laboratory (SNL), Argonne National Laboratory (ANL), Utah State University (USU), and other interested parties with the objective of developing and implementing a comprehensive and readily accessible data and information management system for computational fluid dynamics (CFD) verification and validation (V&V) in support of nuclear energy systems design and safety analysis. The two key objectives of the NE-CAMS effort are to identify, collect, assess, store and maintain high resolution and high quality experimental data and related expert knowledge (metadata) for use in CFD V&V assessments specific to the nuclear energy field and to establish a working relationship with the U.S. Nuclear Regulatory Commission (NRC) to develop a CFD V&V database, including benchmark cases, that addresses and supports the associated NRC regulations and policies on the use of CFD analysis. In particular, the NE-CAMS system will support the Department of Energy Office of Nuclear Energy Advanced Modeling and Simulation (NEAMS) Program, which aims to develop and deploy advanced modeling and simulation methods and computational tools for reliable numerical simulation of nuclear reactor systems for design and safety analysis. Primary NE-CAMS Elements There are four primary elements of the NE-CAMS knowledge base designed to support computer modeling and simulation in the nuclear energy arena as listed below. Element 1. The database will contain experimental data that can be used for CFD validation that is relevant to nuclear reactor and plant processes, particularly those important to the nuclear industry and the NRC. Element 2. Qualification standards for data evaluation and classification will be incorporated and applied such that validation data sets will result in well
Power Take-Off Simulation for Scale Model Testing of Wave Energy Converters
Directory of Open Access Journals (Sweden)
Scott Beatty
2017-07-01
Full Text Available Small scale testing in controlled environments is a key stage in the development of potential wave energy conversion technology. Furthermore, it is well known that the physical design and operational quality of the power-take off (PTO used on the small scale model can have vast effects on the tank testing results. Passive mechanical elements such as friction brakes and air dampers or oil filled dashpots are fraught with nonlinear behaviors such as static friction, temperature dependency, and backlash, the effects of which propagate into the wave energy converter (WEC power production data, causing very high uncertainty in the extrapolation of the tank test results to the meaningful full ocean scale. The lack of quality in PTO simulators is an identified barrier to the development of WECs worldwide. A solution to this problem is to use actively controlled actuators for PTO simulation on small scale model wave energy converters. This can be done using force (or torque-controlled feedback systems with suitable instrumentation, enabling the PTO to exert any desired time and/or state dependent reaction force. In this paper, two working experimental PTO simulators on two different wave energy converters are described. The first implementation is on a 1:25 scale self-reacting point absorber wave energy converter with optimum reactive control. The real-time control system, described in detail, is implemented in LabVIEW. The second implementation is on a 1:20 scale single body point absorber under model-predictive control, implemented with a real-time controller in MATLAB/Simulink. Details on the physical hardware, software, and feedback control methods, as well as results, are described for each PTO. Lastly, both sets of real-time control code are to be web-hosted, free for download, modified and used by other researchers and WEC developers.
Directory of Open Access Journals (Sweden)
Wenlong Tian
2017-09-01
Full Text Available Limited battery energy restricts the duration of the underwater operation of underwater mooring platforms (UMPs. In this paper, a flow-induced vibration energy converter (FIVEC is designed to produce power for the UMPs and extend their operational time. The FIVEC is equipped with a thin plate to capture the kinetic energy in the vortices shed from the surface of the UMP. A magnetic coupling (MC is applied for the non-contacting transmission of the plate torque to the generators so that the friction loss can be minimized. In order to quantify and evaluate the performance of the FIVEC, two-dimensional computational fluid dynamics (CFD simulations are performed. Simulations are based on the Reynolds Averaged Navier-Stokes (RANS equations and the shear stress transport (SST k-ω turbulent model is utilized. The CFD method is firstly validated using existing experimental data. Then the influences of plate length and system damping on the performance of the FIVEC are evaluated. The results show that the device has a maximum averaged power coefficient of 0.0520 (13.86 W in the considered situations. The results also demonstrate the feasibility of this energy converter plan.
International Nuclear Information System (INIS)
Hovestreydt, E.; Karlsruhe Univ.; Parthe, E.; Benedict, U.
1987-01-01
A Fortran 77 computer program is described which allows the simulation of energy dispersive X-ray and synchrotron powder diffraction diagrams. The input consists of structural data (space group, unit cell dimensions, atomic positional and displacement parameters) and information on the experimental conditions (chosen Bragg angle, type of X-ray tube and applied voltage or operating power of synchrotron radiation source). The output consists of the normalized intensities of the diffraction lines, listed by increasing energy (in keV), and of an optional intensity-energy plot. The intensities are calculated with due consideration of the wave-length dependence of both the anomalous dispersion and the absorption coefficients. For a better agreement between observed and calculated spectra provision is made to optionally superimpose, on the calculated diffraction line spectrum, all additional lines such as fluorescence and emission lines and escape peaks. The different effects which have been considered in the simulation are discussed in some detail. A sample calculation of the energy dispersive powder diffraction pattern of UPt 3 (Ni 3 Sn structure type) is given. Warning: the user of ENDIX should be aware that for a successful application it is necessary to adapt the program to correspond to the actual experimental conditions. Even then, due to the only approximately known values of certain functions, the agreement between observed and calculated intensities will not be as good as for angle dispersive diffraction methods
'Odontologic dosimetric card' experiments and simulations using Monte Carlo methods
International Nuclear Information System (INIS)
Menezes, C.J.M.; Lima, R. de A.; Peixoto, J.E.; Vieira, J.W.
2008-01-01
The techniques for data processing, combined with the development of fast and more powerful computers, makes the Monte Carlo methods one of the most widely used tools in the radiation transport simulation. For applications in diagnostic radiology, this method generally uses anthropomorphic phantoms to evaluate the absorbed dose to patients during exposure. In this paper, some Monte Carlo techniques were used to simulation of a testing device designed for intra-oral X-ray equipment performance evaluation called Odontologic Dosimetric Card (CDO of 'Cartao Dosimetrico Odontologico' in Portuguese) for different thermoluminescent detectors. This paper used two computational models of exposition RXD/EGS4 and CDO/EGS4. In the first model, the simulation results are compared with experimental data obtained in the similar conditions. The second model, it presents the same characteristics of the testing device studied (CDO). For the irradiations, the X-ray spectra were generated by the IPEM report number 78, spectrum processor. The attenuated spectrum was obtained for IEC 61267 qualities and various additional filters for a Pantak 320 X-ray industrial equipment. The results obtained for the study of the copper filters used in the determination of the kVp were compared with experimental data, validating the model proposed for the characterization of the CDO. The results shower of the CDO will be utilized in quality assurance programs in order to guarantee that the equipment fulfill the requirements of the Norm SVS No. 453/98 MS (Brazil) 'Directives of Radiation Protection in Medical and Dental Radiodiagnostic'. We conclude that the EGS4 is a suitable code Monte Carlo to simulate thermoluminescent dosimeters and experimental procedures employed in the routine of the quality control laboratory in diagnostic radiology. (author)
Adaptive mesh refinement and adjoint methods in geophysics simulations
Burstedde, Carsten
2013-04-01
It is an ongoing challenge to increase the resolution that can be achieved by numerical geophysics simulations. This applies to considering sub-kilometer mesh spacings in global-scale mantle convection simulations as well as to using frequencies up to 1 Hz in seismic wave propagation simulations. One central issue is the numerical cost, since for three-dimensional space discretizations, possibly combined with time stepping schemes, a doubling of resolution can lead to an increase in storage requirements and run time by factors between 8 and 16. A related challenge lies in the fact that an increase in resolution also increases the dimensionality of the model space that is needed to fully parametrize the physical properties of the simulated object (a.k.a. earth). Systems that exhibit a multiscale structure in space are candidates for employing adaptive mesh refinement, which varies the resolution locally. An example that we found well suited is the mantle, where plate boundaries and fault zones require a resolution on the km scale, while deeper area can be treated with 50 or 100 km mesh spacings. This approach effectively reduces the number of computational variables by several orders of magnitude. While in this case it is possible to derive the local adaptation pattern from known physical parameters, it is often unclear what are the most suitable criteria for adaptation. We will present the goal-oriented error estimation procedure, where such criteria are derived from an objective functional that represents the observables to be computed most accurately. Even though this approach is well studied, it is rarely used in the geophysics community. A related strategy to make finer resolution manageable is to design methods that automate the inference of model parameters. Tweaking more than a handful of numbers and judging the quality of the simulation by adhoc comparisons to known facts and observations is a tedious task and fundamentally limited by the turnaround times
Sánchez-Pérez, J F; Marín, F; Morales, J L; Cánovas, M; Alhama, F
2018-01-01
Mathematical models simulating different and representative engineering problem, atomic dry friction, the moving front problems and elastic and solid mechanics are presented in the form of a set of non-linear, coupled or not coupled differential equations. For different parameters values that influence the solution, the problem is numerically solved by the network method, which provides all the variables of the problems. Although the model is extremely sensitive to the above parameters, no assumptions are considered as regards the linearization of the variables. The design of the models, which are run on standard electrical circuit simulation software, is explained in detail. The network model results are compared with common numerical methods or experimental data, published in the scientific literature, to show the reliability of the model.
2018-01-01
Mathematical models simulating different and representative engineering problem, atomic dry friction, the moving front problems and elastic and solid mechanics are presented in the form of a set of non-linear, coupled or not coupled differential equations. For different parameters values that influence the solution, the problem is numerically solved by the network method, which provides all the variables of the problems. Although the model is extremely sensitive to the above parameters, no assumptions are considered as regards the linearization of the variables. The design of the models, which are run on standard electrical circuit simulation software, is explained in detail. The network model results are compared with common numerical methods or experimental data, published in the scientific literature, to show the reliability of the model. PMID:29518121
Simulation of operation modes of isochronous cyclotron by a new interactive method
International Nuclear Information System (INIS)
Taraszkiewicz, R.; Talach, M.; Sulikowski, J.; Doruch, H.; Norys, T.; Sroka, A.; Kiyan, I.N.; )
2007-01-01
Operation mode simulation methods are based on selection of trim coil currents in the isochronous cyclotron for formation of the required magnetic field at a certain level of the main coil current. The traditional current selection method is based on finding a solution for all trim coils simultaneously. After setting the calculated operation mode, it is usually necessary to perform a control measurement of the magnetic field map and to repeat the calculation for a more accurate solution. The new current selection method is based on successively finding solutions for each particular trim coil. The trim coils are taken one by one in reverse order from the edge to the center of the isochronous cyclotron. The new operation mode simulation method is based on the new current selection method. The new method, as against the traditional one, includes iterative calculation of the kinetic energy at the extraction radius. A series of experiments on proton beam formation within the range of working acceleration radii at extraction energies from 32 to 59 MeV, which were carried out at the AIC144 multipurpose isochronous cyclotron (designed mainly for the eye melanoma treatment and production of radioisotopes) at the INP PAS (Cracow), showed that the new method makes unnecessary any control measurements of magnetic fields for getting the desired operation mode, which indicates a high accuracy of the calculation. (authors)
Simulation of Rossi-α method with analog Monte-Carlo method
International Nuclear Information System (INIS)
Lu Yuzhao; Xie Qilin; Song Lingli; Liu Hangang
2012-01-01
The analog Monte-Carlo code for simulating Rossi-α method based on Geant4 was developed. The prompt neutron decay constant α of six metal uranium configurations in Oak Ridge National Laboratory were calculated. α was also calculated by Burst-Neutron method and the result was consistent with the result of Rossi-α method. There is the difference between results of analog Monte-Carlo simulation and experiment, and the reasons for the difference is the gaps between uranium layers. The influence of gaps decrease as the sub-criticality deepens. The relative difference between results of analog Monte-Carlo simulation and experiment changes from 19% to 0.19%. (authors)
Reduction Methods for Real-time Simulations in Hybrid Testing
DEFF Research Database (Denmark)
Andersen, Sebastian
2016-01-01
Hybrid testing constitutes a cost-effective experimental full scale testing method. The method was introduced in the 1960's by Japanese researchers, as an alternative to conventional full scale testing and small scale material testing, such as shake table tests. The principle of the method...... is performed on a glass fibre reinforced polymer composite box girder. The test serves as a pilot test for prospective real-time tests on a wind turbine blade. The Taylor basis is implemented in the test, used to perform the numerical simulations. Despite of a number of introduced errors in the real...... is to divide a structure into a physical substructure and a numerical substructure, and couple these in a test. If the test is conducted in real-time it is referred to as real time hybrid testing. The hybrid testing concept has developed significantly since its introduction in the 1960', both with respect...
2012-05-30
...-AC46 Energy Conservation Program: Alternative Efficiency Determination Methods and Alternative Rating... regulations authorizing the use of alternative methods of determining energy efficiency or energy consumption... alternative methods of determining energy efficiency or energy consumption of various consumer products and...
Numerical simulations of granular dynamics: I. Hard-sphere discrete element method and tests
Richardson, Derek C.; Walsh, Kevin J.; Murdoch, Naomi; Michel, Patrick
2011-03-01
We present a new particle-based (discrete element) numerical method for the simulation of granular dynamics, with application to motions of particles on small solar system body and planetary surfaces. The method employs the parallel N-body tree code pkdgrav to search for collisions and compute particle trajectories. Collisions are treated as instantaneous point-contact events between rigid spheres. Particle confinement is achieved by combining arbitrary combinations of four provided wall primitives, namely infinite plane, finite disk, infinite cylinder, and finite cylinder, and degenerate cases of these. Various wall movements, including translation, oscillation, and rotation, are supported. We provide full derivations of collision prediction and resolution equations for all geometries and motions. Several tests of the method are described, including a model granular “atmosphere” that achieves correct energy equipartition, and a series of tumbler simulations that show the expected transition from tumbling to centrifuging as a function of rotation rate.
DEFF Research Database (Denmark)
Oropeza-Perez, Ivan; Østergaard, Poul Alberg; Remmen, Arne
2013-01-01
a thermal air flow simulation program - Into the energy systems analysis model. Descriptions of the energy systems in two geographical locations, i.e. Mexico and Denmark, are set up as inputs. Then, the assessment is done by calculating the energy impacts as well as environmental benefits in the energy...
Measurement of ion energy by a calorimetric method
Energy Technology Data Exchange (ETDEWEB)
Mizuhashi, Kiyoshi; Tajima, Satoshi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Bunak, Suwat
1996-12-01
In calorimetric method, ion energy is determined based on the temperature changes during radiation of an absorbing material, radiation current and heat capacity of the calorimeter. This method is convenient and its measuring procedures are simple as well as the measuring apparatus. Here, the temperature changes of the calorimeter during {sup 14}N ion beam radiation were determined. The temperature increased linearly when irradiated with {sup 14}N{sup 3+}, 8.3 MeV or {sup 14}N{sup 2+}, 6 MeV, but not linearly for {sup 14}N{sup 1+}, 3.6 MeV, resulting in a comparatively large error. Thus, the measurement of ion energy by calorimetric method was found available as a convenient method for an accelerator having an energy stability less than 10{sup -3}. Especially this method seems to be useful for low-energy ion accelerator or ion injecting apparatus. (M.N.)
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.
Jun, Gyuchan T; Morris, Zoe; Eldabi, Tillal; Harper, Paul; Naseer, Aisha; Patel, Brijesh; Clarkson, John P
2011-05-19
There is an increasing recognition that modelling and simulation can assist in the process of designing health care policies, strategies and operations. However, the current use is limited and answers to questions such as what methods to use and when remain somewhat underdeveloped. The aim of this study is to provide a mechanism for decision makers in health services planning and management to compare a broad range of modelling and simulation methods so that they can better select and use them or better commission relevant modelling and simulation work. This paper proposes a modelling and simulation method comparison and selection tool developed from a comprehensive literature review, the research team's extensive expertise and inputs from potential users. Twenty-eight different methods were identified, characterised by their relevance to different application areas, project life cycle stages, types of output and levels of insight, and four input resources required (time, money, knowledge and data). The characterisation is presented in matrix forms to allow quick comparison and selection. This paper also highlights significant knowledge gaps in the existing literature when assessing the applicability of particular approaches to health services management, where modelling and simulation skills are scarce let alone money and time. A modelling and simulation method comparison and selection tool is developed to assist with the selection of methods appropriate to supporting specific decision making processes. In particular it addresses the issue of which method is most appropriate to which specific health services management problem, what the user might expect to be obtained from the method, and what is required to use the method. In summary, we believe the tool adds value to the scarce existing literature on methods comparison and selection.
Energy Technology Data Exchange (ETDEWEB)
Araujo, Leonardo Rodrigues de [Instituto Federal do Espirito Santo, Vitoria, ES (Brazil)], E-mail: leoaraujo@ifes.edu.br; Donatelli, Joao Luiz Marcon [Universidade Federal do Espirito Santo (UFES), Vitoria, ES (Brazil)], E-mail: joaoluiz@npd.ufes.br; Silva, Edmar Alino da Cruz [Instituto Tecnologico de Aeronautica (ITA/CTA), Sao Jose dos Campos, SP (Brazil); Azevedo, Joao Luiz F. [Instituto de Aeronautica e Espaco (CTA/IAE/ALA), Sao Jose dos Campos, SP (Brazil)
2010-07-01
Thermal systems are essential in facilities such as thermoelectric plants, cogeneration plants, refrigeration systems and air conditioning, among others, in which much of the energy consumed by humanity is processed. In a world with finite natural sources of fuels and growing energy demand, issues related with thermal system design, such as cost estimative, design complexity, environmental protection and optimization are becoming increasingly important. Therefore the need to understand the mechanisms that degrade energy, improve energy sources use, reduce environmental impacts and also reduce project, operation and maintenance costs. In recent years, a consistent development of procedures and techniques for computational design of thermal systems has occurred. In this context, the fundamental objective of this study is a performance comparative analysis of structural and parametric optimization of a cogeneration system using stochastic methods: genetic algorithm and simulated annealing. This research work uses a superstructure, modelled in a process simulator, IPSEpro of SimTech, in which the appropriate design case studied options are included. Accordingly, the cogeneration system optimal configuration is determined as a consequence of the optimization process, restricted within the configuration options included in the superstructure. The optimization routines are written in MsExcel Visual Basic, in order to work perfectly coupled to the simulator process. At the end of the optimization process, the system optimal configuration, given the characteristics of each specific problem, should be defined. (author)
Multi-criteria ranking of energy generation scenarios with Monte Carlo simulation
International Nuclear Information System (INIS)
Baležentis, Tomas; Streimikiene, Dalia
2017-01-01
Highlights: • Two advanced optimization models were applied for EU energy policy scenarios development. • Several advanced MCDA were applied for energy policy scenarios ranking: WASPAS, ARAS, TOPSIS. • A Monte Carlo simulation was applied for sensitivity analysis of scenarios ranking. • New policy insights in terms of energy scenarios forecasting were provided based on research conducted. - Abstract: Integrated Assessment Models (IAMs) are omnipresent in energy policy analysis. Even though IAMs can successfully handle uncertainty pertinent to energy planning problems, they render multiple variables as outputs of the modelling. Therefore, policy makers are faced with multiple energy development scenarios and goals. Specifically, technical, environmental, and economic aspects are represented by multiple criteria, which, in turn, are related to conflicting objectives. Preferences of decision makers need to be taken into account in order to facilitate effective energy planning. Multi-criteria decision making (MCDM) tools are relevant in aggregating diverse information and thus comparing alternative energy planning options. The paper aims at ranking European Union (EU) energy development scenarios based on several IAMs with respect to multiple criteria. By doing so, we account for uncertainty surrounding policy priorities outside the IAM. In order to follow a sustainable approach, the ranking of policy options is based on EU energy policy priorities: energy efficiency improvements, increased use of renewables, reduction in and low mitigations costs of GHG emission. The ranking of scenarios is based on the estimates rendered by the two advanced IAMs relying on different approaches, namely TIAM and WITCH. The data are fed into the three MCDM techniques: the method of weighted aggregated sum/product assessment (WASPAS), the Additive Ratio Assessment (ARAS) method, and technique for order preference by similarity to ideal solution (TOPSIS). As MCDM techniques allow
Evaluation of binding energies by using quantum mechanical methods
International Nuclear Information System (INIS)
Postolache, Cristian; Matei, Lidia; Postolache, Carmen
2002-01-01
Evaluation of binding energies (BE) in molecular structure is needed for modelling chemical and radiochemical processes by quantum-chemical methods. An important field of application is evaluation of radiolysis and autoradiolysis stability of organic and inorganic compounds as well as macromolecular structures. The current methods of calculation do not allow direct determination of BE but only of total binding energies (TBE) and enthalpies. BEs were evaluated indirectly by determining the homolytic dissociation energies. The molecular structures were built and geometrically optimized by the molecular mechanics methods MM+ and AMBER. The energy minimizations were refined by semi-empirical methods. Depending on the chosen molecular structure, the CNDO, INDO, PM3 and AM1 methods were used. To reach a high confidence level the minimizations were done for gradients lower than 10 -3 RMS. The energy values obtained by the difference of the fragment TBLs, of the transition states and initial molecular structures, respectively, were associated to the hemolytic fragmentation energy and BE, respectively. In order to evaluate the method's accuracy and to establish the application fields of the evaluation methods, the obtained values of BEs were compared with the experimental data taken from literature. To this goal there were built, geometrically optimized by semi-empirical methods and evaluated the BEs for 74 organic and inorganic compounds (alkanes, alkene, alkynes, halogenated derivatives, alcohols, aldehydes, ketones, carboxylic acids, nitrogen and sulfur compounds, water, hydrogen peroxide, ammonia, hydrazine, etc. (authors)
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.
Rapid simulation of spatial epidemics: a spectral method.
Brand, Samuel P C; Tildesley, Michael J; Keeling, Matthew J
2015-04-07
Spatial structure and hence the spatial position of host populations plays a vital role in the spread of infection. In the majority of situations, it is only possible to predict the spatial spread of infection using simulation models, which can be computationally demanding especially for large population sizes. Here we develop an approximation method that vastly reduces this computational burden. We assume that the transmission rates between individuals or sub-populations are determined by a spatial transmission kernel. This kernel is assumed to be isotropic, such that the transmission rate is simply a function of the distance between susceptible and infectious individuals; as such this provides the ideal mechanism for modelling localised transmission in a spatial environment. We show that the spatial force of infection acting on all susceptibles can be represented as a spatial convolution between the transmission kernel and a spatially extended 'image' of the infection state. This representation allows the rapid calculation of stochastic rates of infection using fast-Fourier transform (FFT) routines, which greatly improves the computational efficiency of spatial simulations. We demonstrate the efficiency and accuracy of this fast spectral rate recalculation (FSR) method with two examples: an idealised scenario simulating an SIR-type epidemic outbreak amongst N habitats distributed across a two-dimensional plane; the spread of infection between US cattle farms, illustrating that the FSR method makes continental-scale outbreak forecasting feasible with desktop processing power. The latter model demonstrates which areas of the US are at consistently high risk for cattle-infections, although predictions of epidemic size are highly dependent on assumptions about the tail of the transmission kernel. Copyright © 2015 Elsevier Ltd. All rights reserved.
Simulation of core-level binding energy shifts in germanium-doped lead telluride crystals
International Nuclear Information System (INIS)
Zyubin, A.S.; Dedyulin, S.N.; Yashina, L.V.; Shtanov, V.I.
2007-01-01
To simulate the changes in core-level binding energies in germanium-doped lead telluride, cluster calculations of the changes in the electrostatic potential at the corresponding centers have been performed. Different locations of the Ge atom in the crystal bulk have been considered: near vacancies, near another dopant site, and near the surface. For calculating the potential in the clusters that model the bulk and the surface of the lead telluride crystal (c-PbTe), the electron density obtained in the framework of the Hartree-Fock and hybrid density functional theory (DFT) methods has been used [ru
Microclimate design methods for energy-saving houses on various site conditions in Korea
Energy Technology Data Exchange (ETDEWEB)
Kim, Min Kyeong
2008-07-09
A small area can have several different microclimates depending on how much sunlight, shade or wind are exposed on the area. Microclimate can be influenced by inclined terrain, surfaces, and 3-dimensionally geometry such as combinations of architectural elements and annex buildings. This study investigates microclimate modification for energy-saving using design elements of Korean traditional and passive house. Microclimate analysis method in this study enables to predict temporal and spatial variances in the building geometry. A combination of passive solar heating, cold wind blocking, indoor air circulation, natural ventilation cooling and shading etc, seasonally help to form a comfort condition with less energy consumption. The passive heating and cooling controls with microclimate modification are efficient to accomplish the energy efficiency in the building. This work includes the microclimate modifications of the high-performance designs, microclimate energy-saving methods, Passive House design methods, and common physical bases in energy simulation methods. For hot and humid summer in Korea, ventilation is beneficial for convective or evaporative cooling. The air flow through a building geometry is generated by differences in air temperature and pressure. The layout of surrounding buildings acts as barriers and diverts the flow into narrower. The resulted patterns of airflow are affected more by building geometry and orientation than by air speed. A novel simulation method combining multi-zone and CFD energy simulations is used to analyze energy-saving aspects in passive and microclimate design elements. EnergyPlus is a multi-zone energy simulation tool that uses a parameterization to simplify the energy-saving problem for each zone. However, the model is not appropriate to handle variations in the building geometry since it estimates only the average value for each volume. On the contrary, CFD method with subdivided grid units is more suitable to estimate
Discrete vortex method simulations of aerodynamic admittance in bridge aerodynamics
DEFF Research Database (Denmark)
Rasmussen, Johannes Tophøj; Hejlesen, Mads Mølholm; Larsen, Allan
, and to determine aerodynamic forces and the corresponding ﬂutter limit. A simulation of the three-dimensional bridge responseto turbulent wind is carried out by quasi steady theory by modelling the bridge girder as a line like structure [2], applying the aerodynamic load coefﬁcients found from the current version......The meshless and remeshed Discrete Vortex Method (DVM) has been widely used in academia and by the industry to model two-dimensional ﬂow around bluff bodies. The implementation “DVMFLOW” [1] is used by the bridge design company COWI to determine and visualise the ﬂow ﬁeld around bridge sections...
Numerical Simulation of Plasma Antenna with FDTD Method
International Nuclear Information System (INIS)
Chao, Liang; Yue-Min, Xu; Zhi-Jiang, Wang
2008-01-01
We adopt cylindrical-coordinate FDTD algorithm to simulate and analyse a 0.4-m-long column configuration plasma antenna. FDTD method is useful for solving electromagnetic problems, especially when wave characteristics and plasma properties are self-consistently related to each other. Focus on the frequency from 75 MHz to 400 MHz, the input impedance and radiation efficiency of plasma antennas are computed. Numerical results show that, different from copper antenna, the characteristics of plasma antenna vary simultaneously with plasma frequency and collision frequency. The property can be used to construct dynamically reconBgurable antenna. The investigation is meaningful and instructional for the optimization of plasma antenna design
Numerical simulation of plasma antenna with FDTD method
International Nuclear Information System (INIS)
Liang Chao; Xu Yuemin; Wang Zhijiang
2008-01-01
We adopt cylindrical-coordinate FDTD algorithm to simulate and analyse a 0.4-m-long column configuration plasma antenna. FDTD method is useful for solving electromagnetic problems, especially when wave characteristics and plasma properties are self-consistently related to each other. Focus on the frequency from 75 MHz to 400 MHz, the input impedance and radiation efficiency of plasma antennas are computed. Numerical results show that, different from copper antenna, the characteristics of plasma antenna vary simultaneously with plasma frequency and collision frequency. The property can be used to construct dynamically reconfigurable antenna. The investigation is meaningful and instructional for the optimization of plasma antenna design. (authors)
Serçinoglu, Onur; Ozbek, Pemra
2018-05-25
Atomistic molecular dynamics (MD) simulations generate a wealth of information related to the dynamics of proteins. If properly analyzed, this information can lead to new insights regarding protein function and assist wet-lab experiments. Aiming to identify interactions between individual amino acid residues and the role played by each in the context of MD simulations, we present a stand-alone software called gRINN (get Residue Interaction eNergies and Networks). gRINN features graphical user interfaces (GUIs) and a command-line interface for generating and analyzing pairwise residue interaction energies and energy correlations from protein MD simulation trajectories. gRINN utilizes the features of NAMD or GROMACS MD simulation packages and automatizes the steps necessary to extract residue-residue interaction energies from user-supplied simulation trajectories, greatly simplifying the analysis for the end-user. A GUI, including an embedded molecular viewer, is provided for visualization of interaction energy time-series, distributions, an interaction energy matrix, interaction energy correlations and a residue correlation matrix. gRINN additionally offers construction and analysis of Protein Energy Networks, providing residue-based metrics such as degrees, betweenness-centralities, closeness centralities as well as shortest path analysis. gRINN is free and open to all users without login requirement at http://grinn.readthedocs.io.