Simulator for candu600 fuel handling system. the experimental model
International Nuclear Information System (INIS)
Marinescu, N.; Predescu, D.; Valeca, S.
2013-01-01
A main way to increase the nuclear plant safety is related to selection and continuous training of the operation staff. In this order, the computer programs for training, testing and evaluation of the knowledge get, or training simulators including the advanced analytical models of the technological systems are using. The Institute for Nuclear Research from Pitesti, Romania intend to design and build an Fuel Handling Simulator at his F/M Head Test Rig facility, that will be used for training of operating personnel. This paper presents simulated system, advantages to use the simulator, and the experimental model of simulator, that has been built to allows setting of the requirements and fabrication details, especially for the software kit that will be designed and implement on main simulator. (authors)
Low dose CT simulation using experimental noise model
Energy Technology Data Exchange (ETDEWEB)
Nakanishi, Satori; Zamyatin, Alexander A. [Toshiba Medical Systems Corporation, Tochigi, Otawarashi (Japan); Silver, Michael D. [Toshiba Medical Research Institute, Vernon Hills, IL (United States)
2011-07-01
We suggest a method to obtain system noise model experimentally without relying on assumptions on statistical distribution of the noise; also, knowledge of DAS gain and electronic noise level are not required. Evaluation with ultra-low dose CT data (5 mAs) shows good match between simulated and real data noise. (orig.)
A sEMG model with experimentally based simulation parameters.
Wheeler, Katherine A; Shimada, Hiroshima; Kumar, Dinesh K; Arjunan, Sridhar P
2010-01-01
A differential, time-invariant, surface electromyogram (sEMG) model has been implemented. While it is based on existing EMG models, the novelty of this implementation is that it assigns more accurate distributions of variables to create realistic motor unit (MU) characteristics. Variables such as muscle fibre conduction velocity, jitter (the change in the interpulse interval between subsequent action potential firings) and motor unit size have been considered to follow normal distributions about an experimentally obtained mean. In addition, motor unit firing frequencies have been considered to have non-linear and type based distributions that are in accordance with experimental results. Motor unit recruitment thresholds have been considered to be related to the MU type. The model has been used to simulate single channel differential sEMG signals from voluntary, isometric contractions of the biceps brachii muscle. The model has been experimentally verified by conducting experiments on three subjects. Comparison between simulated signals and experimental recordings shows that the Root Mean Square (RMS) increases linearly with force in both cases. The simulated signals also show similar values and rates of change of RMS to the experimental signals.
Tyre tread-block friction: modelling, simulation and experimental validation
Wallaschek, Jörg; Wies, Burkard
2013-07-01
Pneumatic tyres are used in vehicles since the beginning of the last century. They generate braking and steering forces for bicycles, motor cycles, cars, busses, trucks, agricultural vehicles and aircraft. These forces are generated in the usually very small contact area between tyre and road and their performance characteristics are of eminent importance for safety and comfort. Much research has been addressed to optimise tyre design with respect to footprint pressure and friction. In this context, the development of virtual tyre prototypes, that is, simulation models for the tyre, has grown to a science in its own. While the modelling of the structural dynamics of the tyre has reached a very advanced level, which allows to take into account effects like the rate-independent inelasticity of filled elastomers or the transient 3D deformations of the ply-reinforced tread, shoulder and sidewalls, little is known about the friction between tread-block elements and road. This is particularly obvious in the case when snow, ice, water or a third-body layer are present in the tyre-road contact. In the present paper, we give a survey on the present state of knowledge in the modelling, simulation and experimental validation of tyre tread-block friction processes. We concentrate on experimental techniques.
Experimental Design for Sensitivity Analysis of Simulation Models
Kleijnen, J.P.C.
2001-01-01
This introductory tutorial gives a survey on the use of statistical designs for what if-or sensitivity analysis in simulation.This analysis uses regression analysis to approximate the input/output transformation that is implied by the simulation model; the resulting regression model is also known as
Numerical simulation and experimental validation of aircraft ground deicing model
Directory of Open Access Journals (Sweden)
Bin Chen
2016-05-01
Full Text Available Aircraft ground deicing plays an important role of guaranteeing the aircraft safety. In practice, most airports generally use as many deicing fluids as possible to remove the ice, which causes the waste of the deicing fluids and the pollution of the environment. Therefore, the model of aircraft ground deicing should be built to establish the foundation for the subsequent research, such as the optimization of the deicing fluid consumption. In this article, the heat balance of the deicing process is depicted, and the dynamic model of the deicing process is provided based on the analysis of the deicing mechanism. In the dynamic model, the surface temperature of the deicing fluids and the ice thickness are regarded as the state parameters, while the fluid flow rate, the initial temperature, and the injection time of the deicing fluids are treated as control parameters. Ignoring the heat exchange between the deicing fluids and the environment, the simplified model is obtained. The rationality of the simplified model is verified by the numerical simulation and the impacts of the flow rate, the initial temperature and the injection time on the deicing process are investigated. To verify the model, the semi-physical experiment system is established, consisting of the low-constant temperature test chamber, the ice simulation system, the deicing fluid heating and spraying system, the simulated wing, the test sensors, and the computer measure and control system. The actual test data verify the validity of the dynamic model and the accuracy of the simulation analysis.
Simulation and Experimental Works of Quadcopter Model for Simple Maneuver
Directory of Open Access Journals (Sweden)
Rafiuddin Syam
2017-03-01
Full Text Available This study aims to create a simulated and experimental of aircraft movements for multirotor quadcopter. The research method is theoretical and experimental methods. For theoretical method consists of calculating the dynamics and kinematics. While the experimental method consists of the aircraft testing and processing of GPS data recorded aircraft. The results showed that the acceleration acting on the aircraft is large enough that x ̈ = 1.751 m/s2, y = 2.038 m /s2 = 1.6371 m danz ̈ / s2, (2 the value of the maximum error between the theoretical and the actual movement is ex = 0.682 m; ey and ez = 0.353 m = 0.546 m. Theoretical movement pattern already resembles the actual movement
Simulation and Experimental Works of Quadcopter Model for Simple Maneuver
Directory of Open Access Journals (Sweden)
Rafiuddin Syam
2015-03-01
Full Text Available This study aims to create a simulated and experimental of aircraft movements for multirotor quadcopter. The research method is theoretical and experimental methods. For theoretical method consists of calculating the dynamics and kinematics. While the experimental method consists of the aircraft testing and processing of GPS data recorded aircraft. The results showed that the acceleration acting on the aircraft is large enough that x ̈ = 1.751 m/s2, y = 2.038 m /s2 = 1.6371 m and z ̈ / s2, (2 the value of the maximum error between the theoretical and the actual movement is ex = 0.682 m; ey and ez = 0.353 m = 0.546 m. Theoretical movement pattern already resembles the actual movement.
Hypersonic Combustor Model Inlet CFD Simulations and Experimental Comparisons
Venkatapathy, E.; TokarcikPolsky, S.; Deiwert, G. S.; Edwards, Thomas A. (Technical Monitor)
1995-01-01
Numerous two-and three-dimensional computational simulations were performed for the inlet associated with the combustor model for the hypersonic propulsion experiment in the NASA Ames 16-Inch Shock Tunnel. The inlet was designed to produce a combustor-inlet flow that is nearly two-dimensional and of sufficient mass flow rate for large scale combustor testing. The three-dimensional simulations demonstrated that the inlet design met all the design objectives and that the inlet produced a very nearly two-dimensional combustor inflow profile. Numerous two-dimensional simulations were performed with various levels of approximations such as in the choice of chemical and physical models, as well as numerical approximations. Parametric studies were conducted to better understand and to characterize the inlet flow. Results from the two-and three-dimensional simulations were used to predict the mass flux entering the combustor and a mass flux correlation as a function of facility stagnation pressure was developed. Surface heat flux and pressure measurements were compared with the computed results and good agreement was found. The computational simulations helped determine the inlet low characteristics in the high enthalpy environment, the important parameters that affect the combustor-inlet flow, and the sensitivity of the inlet flow to various modeling assumptions.
Experimental Benchmarking of Fire Modeling Simulations. Final Report
International Nuclear Information System (INIS)
Greiner, Miles; Lopez, Carlos
2003-01-01
A series of large-scale fire tests were performed at Sandia National Laboratories to simulate a nuclear waste transport package under severe accident conditions. The test data were used to benchmark and adjust the Container Analysis Fire Environment (CAFE) computer code. CAFE is a computational fluid dynamics fire model that accurately calculates the heat transfer from a large fire to a massive engulfed transport package. CAFE will be used in transport package design studies and risk analyses
Studies of turbulent round jets through experimentation, simulation, and modeling
Keedy, Ryan
analysis computationally taxing. A Probability Density Function (PDF) model for the concentration of scalars, as well as for the droplet number in different size bins, is developed. The growth of droplets as they evolve along the jet, for different downstream and radial positions, compared favorably with experimental measurements in the literature. We utilized a graphical processing unit with the PDF method to more efficiently compute the statistics of the droplet diameter in the non-uniform supersaturation field.
Melt pool modelling, simulation and experimental validation for SLM
Wits, Wessel
2017-01-01
SLM parts are built by successively melting layers of powder in a powder bed. Process parameters are often optimized experimentally by laser scanning a number of single tracks and subsequently determining which settings lead to a good compromise between quality and build speed. However,
Models, simulation, and experimental issues in structural mechanics
Maceri, Franco; Vairo, Giuseppe
2017-01-01
The reader aware in Structural Mechanics will find in this book a source of fruitful knowledge and effective tools useful for imagining, creating, and promoting novel and challenging developments. It addresses a wide range of topics, such as mechanics and geotechnics, vibration and damping, damage and friction, experimental methods, and advanced structural materials. It also discusses analytical, experimental and numerical findings, focusing on theoretical and practical issues, and leading to innovations in the field. Collecting some of the latest results from the Lagrange Laboratory, a European scientific research group, mainly consisting of Italian and French engineers, mechanicians and mathematicians, the book presents the most recent example of the long-term scientific cooperation between well-established French and Italian Mechanics, Mathematics and Engineering Schools. .
Study on driver model for hybrid truck based on driving simulator experimental results
Directory of Open Access Journals (Sweden)
Dam Hoang Phuc
2018-04-01
Full Text Available In this paper, a proposed car-following driver model taking into account some features of both the compensatory and anticipatory model representing the human pedal operation has been verified by driving simulator experiments with several real drivers. The comparison between computer simulations performed by determined model parameters with the experimental results confirm the correctness of this mathematical driver model and identified model parameters. Then the driver model is joined to a hybrid vehicle dynamics model and the moderate car following maneuver simulations with various driver parameters are conducted to investigate influences of driver parameters on vehicle dynamics response and fuel economy. Finally, major driver parameters involved in the longitudinal control of drivers are clarified. Keywords: Driver model, Driver-vehicle closed-loop system, Car Following, Driving simulator/hybrid electric vehicle (B1
DEFF Research Database (Denmark)
de Souza Reboucas, Geraldo Francisco; Santos, Ilmar; Thomsen, Jon Juel
2017-01-01
The frequency response of a single-degree of freedom vibro-impact oscillator is analysed using Harmonic Linearization, Averaging and Numeric Simulations considering two different impact force models, one given by a piecewise-linear function and other by a high-order polynomial. Experimental...
The NASA Ames Hypersonic Combustor-Model Inlet CFD Simulations and Experimental Comparisons
Venkatapathy, E.; Tokarcik-Polsky, S.; Deiwert, G. S.; Edwards, Thomas A. (Technical Monitor)
1995-01-01
Computations have been performed on a three-dimensional inlet associated with the NASA Ames combustor model for the hypersonic propulsion experiment in the 16-inch shock tunnel. The 3-dimensional inlet was designed to have the combustor inlet flow nearly two-dimensional and of sufficient mass flow necessary for combustion. The 16-inch shock tunnel experiment is a short duration test with test time of the order of milliseconds. The flow through the inlet is in chemical non-equilibrium. Two test entries have been completed and limited experimental results for the inlet region of the combustor-model are available. A number of CFD simulations, with various levels of simplifications such as 2-D simulations, 3-D simulations with and without chemical reactions, simulations with and without turbulent conditions, etc., have been performed. These simulations have helped determine the model inlet flow characteristics and the important factors that affect the combustor inlet flow and the sensitivity of the flow field to these simplifications. In the proposed paper, CFD modeling of the hypersonic inlet, results from the simulations and comparison with available experimental results will be presented.
Ball bearing defect models: A study of simulated and experimental fault signatures
Mishra, C.; Samantaray, A. K.; Chakraborty, G.
2017-07-01
Numerical model based virtual prototype of a system can serve as a tool to generate huge amount of data which replace the dependence on expensive and often difficult to conduct experiments. However, the model must be accurate enough to substitute the experiments. The abstraction level and details considered during model development depend on the purpose for which simulated data should be generated. This article concerns development of simulation models for deep groove ball bearings which are used in a variety of rotating machinery. The purpose of the model is to generate vibration signatures which usually contain features of bearing defects. Three different models with increasing level-of-complexity are considered: a bearing kinematics based planar motion block diagram model developed in MATLAB Simulink which does not explicitly consider cage and traction dynamics, a planar motion model with cage, traction and contact dynamics developed using multi-energy domain bond graph formalism in SYMBOLS software, and a detailed spatial multi-body dynamics model with complex contact and traction mechanics developed using ADAMS software. Experiments are conducted using Spectra Quest machine fault simulator with different prefabricated faulted bearings. The frequency domain characteristics of simulated and experimental vibration signals for different bearing faults are compared and conclusions are drawn regarding usefulness of the developed models.
Pyrolysis of Municipal Green Waste: A Modelling, Simulation and Experimental Analysis
Directory of Open Access Journals (Sweden)
Mohammed J. Kabir
2015-07-01
Full Text Available Pyrolysis is the thermo-chemical conversion of carbonaceous feedstock in the absence of oxygen to produce bio-fuel (bio-oil, bio-char and syn-gas. Bio-fuel production from municipal green waste (MGW through the pyrolysis process has attracted considerable attention recently in the renewable energy sector because it can reduce greenhouse gas emissions and contribute to energy security. This study analyses properties of MGW feedstock available in Rockhampton city of Central Queensland, Australia, and presents an experimental investigation of producing bio-fuel from that MGW through the pyrolysis process using a short sealed rotary furnace. It was found from the experiment that about 19.97% bio-oil, 40.83% bio-char and 29.77% syn-gas can be produced from the MGW. Then, a four-stage steady state simulation model is developed for pyrolysis process performance simulation using Aspen Plus software. In the first stage, the moisture content of the MGW feed is reduced. In the second stage, the MGW is decomposed according to its elemental constituents. In the third stage, condensate material is separated and, finally, the pyrolysis reactions are modelled using the Gibbs free energy minimisation approach. The MGW’s ultimate and proximate analysis data were used in the Aspen Plus simulation as input parameters. The model is validated with experimentally measured data. A good agreement between simulation and experimental results was found. More specifically, the variation of modelling and experimental elemental compositions of the MGW was found to be 7.3% for carbon, 15.82% for hydrogen, 7.04% for nitrogen and 5.56% for sulphur. The validated model is used to optimise the biofuel production from the MGW as a function of operating variables such as temperature, moisture content, particle size and process heat air–fuel ratio. The modelling and optimisation results are presented, analysed and discussed.
Verification of simulation model with COBRA-IIIP code by confrontment of experimental results
International Nuclear Information System (INIS)
Silva Galetti, M.R. da; Pontedeiro, A.C.; Oliveira Barroso, A.C. de
1985-01-01
It is presented an evaluation of the COBRA IIIP/MIT code (of thermal hydraulic analysis by subchannels), comparing their results with experimental data obtained in stationary and transient regimes. It was done a study to calculate the spatial and temporal critical heat flux. It is presented a sensitivity study of simulation model related to the turbulent mixture and the number of axial intervals. (M.C.K.) [pt
A hierarchy of models for simulating experimental results from a 3D heterogeneous porous medium
Vogler, Daniel; Ostvar, Sassan; Paustian, Rebecca; Wood, Brian D.
2018-04-01
In this work we examine the dispersion of conservative tracers (bromide and fluorescein) in an experimentally-constructed three-dimensional dual-porosity porous medium. The medium is highly heterogeneous (σY2 = 5.7), and consists of spherical, low-hydraulic-conductivity inclusions embedded in a high-hydraulic-conductivity matrix. The bimodal medium was saturated with tracers, and then flushed with tracer-free fluid while the effluent breakthrough curves were measured. The focus for this work is to examine a hierarchy of four models (in the absence of adjustable parameters) with decreasing complexity to assess their ability to accurately represent the measured breakthrough curves. The most information-rich model was (1) a direct numerical simulation of the system in which the geometry, boundary and initial conditions, and medium properties were fully independently characterized experimentally with high fidelity. The reduced-information models included; (2) a simplified numerical model identical to the fully-resolved direct numerical simulation (DNS) model, but using a domain that was one-tenth the size; (3) an upscaled mobile-immobile model that allowed for a time-dependent mass-transfer coefficient; and, (4) an upscaled mobile-immobile model that assumed a space-time constant mass-transfer coefficient. The results illustrated that all four models provided accurate representations of the experimental breakthrough curves as measured by global RMS error. The primary component of error induced in the upscaled models appeared to arise from the neglect of convection within the inclusions. We discuss the necessity to assign value (via a utility function or other similar method) to outcomes if one is to further select from among model options. Interestingly, these results suggested that the conventional convection-dispersion equation, when applied in a way that resolves the heterogeneities, yields models with high fidelity without requiring the imposition of a more
Directory of Open Access Journals (Sweden)
Yuanyuan Ma
2018-01-01
Full Text Available This paper focuses on the modeling, simulation, and experimental verification of wideband single-input single-output (SISO mobile fading channels for indoor propagation environments. The indoor reference channel model is derived from a geometrical rectangle scattering model, which consists of an infinite number of scatterers. It is assumed that the scatterers are exponentially distributed over the two-dimensional (2D horizontal plane of a rectangular room. Analytical expressions are derived for the probability density function (PDF of the angle of arrival (AOA, the PDF of the propagation path length, the power delay profile (PDP, and the frequency correlation function (FCF. An efficient sum-of-cisoids (SOC channel simulator is derived from the nonrealizable reference model by employing the SOC principle. It is shown that the SOC channel simulator approximates closely the reference model with respect to the FCF. The SOC channel simulator enables the performance evaluation of wideband indoor wireless communication systems with reduced realization expenditure. Moreover, the rationality and usefulness of the derived indoor channel model is confirmed by various measurements at 2.4, 5, and 60 GHz.
An experimentally validated simulation model for a four-stage spray dryer
DEFF Research Database (Denmark)
Petersen, Lars Norbert; Poulsen, Niels Kjølstad; Niemann, Hans Henrik
2017-01-01
mathematical model is an index-1 differential algebraic equation (DAE) model with 12 states, 9 inputs, 8 disturbances, and 30 parameters. The parameters in the model are identified from well-excited experimental data obtained from the industrialtype spray dryer. The simulated outputs ofthe model are validated...... is divided into four consecutive stages: a primary spray drying stage, two heated fluid bed stages, and a cooling fluid bed stage. Each of these stages in the model is assumed ideally mixed and the dynamics are described by mass- and energy balances. These balance equations are coupled with constitutive...... equations such as a thermodynamic model, the water evaporation rate, the heat transfer rates, and an equation for the stickiness of the powder (glass transition temperature). Laboratory data is used to model the equilibrium moisture content and the glass transition temperature of the powder. The resulting...
Combining experimental and simulation data of molecular processes via augmented Markov models.
Olsson, Simon; Wu, Hao; Paul, Fabian; Clementi, Cecilia; Noé, Frank
2017-08-01
Accurate mechanistic description of structural changes in biomolecules is an increasingly important topic in structural and chemical biology. Markov models have emerged as a powerful way to approximate the molecular kinetics of large biomolecules while keeping full structural resolution in a divide-and-conquer fashion. However, the accuracy of these models is limited by that of the force fields used to generate the underlying molecular dynamics (MD) simulation data. Whereas the quality of classical MD force fields has improved significantly in recent years, remaining errors in the Boltzmann weights are still on the order of a few [Formula: see text], which may lead to significant discrepancies when comparing to experimentally measured rates or state populations. Here we take the view that simulations using a sufficiently good force-field sample conformations that are valid but have inaccurate weights, yet these weights may be made accurate by incorporating experimental data a posteriori. To do so, we propose augmented Markov models (AMMs), an approach that combines concepts from probability theory and information theory to consistently treat systematic force-field error and statistical errors in simulation and experiment. Our results demonstrate that AMMs can reconcile conflicting results for protein mechanisms obtained by different force fields and correct for a wide range of stationary and dynamical observables even when only equilibrium measurements are incorporated into the estimation process. This approach constitutes a unique avenue to combine experiment and computation into integrative models of biomolecular structure and dynamics.
International Nuclear Information System (INIS)
Doi, M.; Tanaka, N.; Fuma, S.; Kawabata, Z.
2004-01-01
Well-designed experimental model ecosystem could be a simple reference of the actual environment and complex ecological systems. For ecological toxicity test of radiation and other environmental toxicants, we investigated and aquatic microbial ecosystem (closed microcosm) in the test tube with initial substrates,autotroph flagellate algae (Euglena, G.), heterotroph ciliate protozoa (Tetrahymena T.) and saprotroph bacteria (E, coli). These species organizes by itself to construct the ecological system, that keeps the sustainable population dynamics for more than 2 years after inoculation only by adding light diurnally and controlling temperature at 25 degree Celsius. Objective of the study is to develop the particle-based computer simulation by reviewing interactions among microbes and environment, and analyze the ecological toxicities of radiation on the microcosm by replicating experimental results in the computer simulation. (Author) 14 refs
Energy Technology Data Exchange (ETDEWEB)
Yun, Sung Mi; Kang, Christina S. [Department of Environmental Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 143-701 (Korea, Republic of); Kim, Jonghwa [Department of Industrial Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 143-701 (Korea, Republic of); Kim, Han S., E-mail: hankim@konkuk.ac.kr [Department of Environmental Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 143-701 (Korea, Republic of)
2015-04-28
Highlights: • Remediation of complex contaminated soil achieved by sequential soil flushing. • Removal of Zn, Pb, and heavy petroleum oils using 0.05 M citric acid and 2% SDS. • Unified desorption distribution coefficients modeled and experimentally determined. • Nonequilibrium models for the transport behavior of complex contaminants in soils. - Abstract: The removal of heavy metals (Zn and Pb) and heavy petroleum oils (HPOs) from a soil with complex contamination was examined by soil flushing. Desorption and transport behaviors of the complex contaminants were assessed by batch and continuous flow reactor experiments and through modeling simulations. Flushing a one-dimensional flow column packed with complex contaminated soil sequentially with citric acid then a surfactant resulted in the removal of 85.6% of Zn, 62% of Pb, and 31.6% of HPO. The desorption distribution coefficients, K{sub Ubatch} and K{sub Lbatch}, converged to constant values as C{sub e} increased. An equilibrium model (ADR) and nonequilibrium models (TSNE and TRNE) were used to predict the desorption and transport of complex contaminants. The nonequilibrium models demonstrated better fits with the experimental values obtained from the column test than the equilibrium model. The ranges of K{sub Ubatch} and K{sub Lbatch} were very close to those of K{sub Ufit} and K{sub Lfit} determined from model simulations. The parameters (R, β, ω, α, and f) determined from model simulations were useful for characterizing the transport of contaminants within the soil matrix. The results of this study provide useful information for the operational parameters of the flushing process for soils with complex contamination.
Simulation and experimental validation of the dynamical model of a dual-rotor vibrotactor
Miklós, Á.; Szabó, Z.
2015-01-01
In this work, a novel design for small vibrotactors called the Dual Excenter is presented, which makes it possible to produce vibrations with independently adjustable frequency and amplitude. This feature has been realized using two coaxially aligned eccentric rotors, which are driven by DC motors independently. The prototype of the device has been built, where mechanical components are integrated on a frame with two optical sensors for the measurement of angular velocity and phase angle. The system is equipped with a digital controller. Simulations confirm the results of analytical investigations and they allow us to model the sampling method of the signals of the angular velocity and the phase angle between the rotors. Furthermore, we model the discrete behavior of the controller, which is a PI controller for the angular velocities and a PID controller for the phase angle. Finally, simulation results are compared to experimental ones, which show that the Dual Excenter concept is feasible.
MATLAB/Simulink Pulse-Echo Ultrasound System Simulator Based on Experimentally Validated Models.
Kim, Taehoon; Shin, Sangmin; Lee, Hyongmin; Lee, Hyunsook; Kim, Heewon; Shin, Eunhee; Kim, Suhwan
2016-02-01
A flexible clinical ultrasound system must operate with different transducers, which have characteristic impulse responses and widely varying impedances. The impulse response determines the shape of the high-voltage pulse that is transmitted and the specifications of the front-end electronics that receive the echo; the impedance determines the specification of the matching network through which the transducer is connected. System-level optimization of these subsystems requires accurate modeling of pulse-echo (two-way) response, which in turn demands a unified simulation of the ultrasonics and electronics. In this paper, this is realized by combining MATLAB/Simulink models of the high-voltage transmitter, the transmission interface, the acoustic subsystem which includes wave propagation and reflection, the receiving interface, and the front-end receiver. To demonstrate the effectiveness of our simulator, the models are experimentally validated by comparing the simulation results with the measured data from a commercial ultrasound system. This simulator could be used to quickly provide system-level feedback for an optimized tuning of electronic design parameters.
Javaherchi, Teymour; Stelzenmuller, Nick; Seydel, Joseph; Aliseda, Alberto
2014-11-01
The performance, turbulent wake evolution and interaction of multiple Horizontal Axis Hydrokinetic Turbines (HAHT) is analyzed in a 45:1 scale model setup. We combine experimental measurements with different RANS-based computational simulations that model the turbines with sliding-mesh, rotating reference frame and blame element theory strategies. The influence of array spacing and Tip Speed Ratio on performance and wake velocity structure is investigated in three different array configurations: Two coaxial turbines at different downstream spacing (5d to 14d), Three coaxial turbines with 5d and 7d downstream spacing, and Three turbines with lateral offset (0.5d) and downstream spacing (5d & 7d). Comparison with experimental measurements provides insights into the dynamics of HAHT arrays, and by extension to closely packed HAWT arrays. The experimental validation process also highlights the influence of the closure model used (k- ω SST and k- ɛ) and the flow Reynolds number (Re=40,000 to 100,000) on the computational predictions of devices' performance and characteristics of the flow field inside the above-mentioned arrays, establishing the strengths and limitations of existing numerical models for use in industrially-relevant settings (computational cost and time). Supported by DOE through the National Northwest Marine Renewable Energy Center (NNMREC).
Hydrological Modelling Using a Rainfall Simulator over an Experimental Hillslope Plot
Directory of Open Access Journals (Sweden)
Arpit Chouksey
2017-03-01
Full Text Available Hydrological processes are complex to compute in hilly areas when compared to plain areas. The governing processes behind runoff generation on hillslopes are subsurface storm flow, saturation excess flow, overland flow, return flow and pipe storage. The simulations of the above processes in the soil matrix require detailed hillslope hydrological modelling. In the present study, a hillslope experimental plot has been designed to study the runoff generation processes on the plot scale. The setup is designed keeping in view the natural hillslope conditions prevailing in the Northwestern Himalayas, India where high intensity rainfall events occur frequently. A rainfall simulator was installed over the experimental hillslope plot to generate rainfall with an intensity of 100 mm/h, which represents the dominating rainfall intensity range in the region. Soil moisture sensors were also installed at variable depths from 100 to 1000 mm at different locations of the plot to observe the soil moisture regime. From the experimental observations it was found that once the soil is saturated, it remains at field capacity for the next 24–36 h. Such antecedent moisture conditions are most favorable for the generation of rapid stormflow from hillslopes. A dye infiltration test was performed on the undisturbed soil column to observe the macropore fraction variability over the vegetated hillslopes. The estimated macropore fractions are used as essential input for the hillslope hydrological model. The main objective of the present study was to develop and test a method for estimating runoff responses from natural rainfall over hillslopes of the Northwestern Himalayas using a portable rainfall simulator. Using the experimental data and the developed conceptual model, the overland flow and the subsurface flow through a macropore-dominated area have been estimated/analyzed. The surface and subsurface runoff estimated using the developed hillslope hydrological model
Directory of Open Access Journals (Sweden)
Ping Li
2018-03-01
Full Text Available In this paper, performances of vibration energy harvester combined piezoelectric (PE and electromagnetic (EM mechanism are studied by theoretical analysis, simulation and experimental test. For the designed harvester, electromechanical coupling modeling is established, and expressions of vibration response, output voltage, current and power are derived. Then, performances of the harvester are simulated and tested; moreover, the power charging rechargeable battery is realized through designed energy storage circuit. By the results, it’s found that compared with piezoelectric-only and electromagnetic-only energy harvester, the hybrid energy harvester can enhance the output power and harvesting efficiency; furthermore, at the harmonic excitation, output power of harvester linearly increases with acceleration amplitude increasing; while it enhances with acceleration spectral density increasing at the random excitation. In addition, the bigger coupling strength, the bigger output power is, and there is the optimal load resistance to make the harvester output the maximal power.
International Nuclear Information System (INIS)
Goldberg, L.F.
1990-08-01
The activities described in this report do not constitute a continuum but rather a series of linked smaller investigations in the general area of one- and two-dimensional Stirling machine simulation. The initial impetus for these investigations was the development and construction of the Mechanical Engineering Test Rig (METR) under a grant awarded by NASA to Dr. Terry Simon at the Department of Mechanical Engineering, University of Minnesota. The purpose of the METR is to provide experimental data on oscillating turbulent flows in Stirling machine working fluid flow path components (heater, cooler, regenerator, etc.) with particular emphasis on laminar/turbulent flow transitions. Hence, the initial goals for the grant awarded by NASA were, broadly, to provide computer simulation backup for the design of the METR and to analyze the results produced. This was envisaged in two phases: First, to apply an existing one-dimensional Stirling machine simulation code to the METR and second, to adapt a two-dimensional fluid mechanics code which had been developed for simulating high Rayleigh number buoyant cavity flows to the METR. The key aspect of this latter component was the development of an appropriate turbulence model suitable for generalized application to Stirling simulation. A final-step was then to apply the two-dimensional code to an existing Stirling machine for which adequate experimental data exist. The work described herein was carried out over a period of three years on a part-time basis. Forty percent of the first year's funding was provided as a match to the NASA funds by the Underground Space Center, University of Minnesota, which also made its computing facilities available to the project at no charge
Directory of Open Access Journals (Sweden)
George Perry
2016-10-01
Full Text Available The amount of palaeoecological information available continues to grow rapidly, providing improved descriptions of the dynamics of past ecosystems and enabling them to be seen from new perspectives. At the same time, there has been concern over whether palaeoecological enquiry needs to move beyond descriptive inference to a more hypothesis-focussed or experimental approach; however, the extent to which conventional hypothesis-driven scientific frameworks can be applied to historical contexts (i.e., the past is the subject of ongoing debate. In other disciplines concerned with human-environment interactions, including physical geography and archaeology, there has been growing use of generative simulation models, typified by agent-based approaches. Generative modelling encourages counter-factual questioning (what if…?, a mode of argument that is particularly important in systems and time-periods, such as the Holocene and now the Anthropocene, where the effects of humans and other biophysical processes are deeply intertwined. However, palaeoecologically focused simulation of the dynamics of the ecosystems of the past either seems to be conducted to assess the applicability of some model to the future or treats humans simplistically as external forcing factors. In this review we consider how generative simulation-modelling approaches could contribute to our understanding of past human-environment interactions. We consider two key issues: the need for null models for understanding past dynamics and the need to be able learn more from pattern-based analysis. In this light, we argue that there is considerable scope for palaeocology to benefit from developments in generative models and their evaluation. We discuss the view that simulation is a form of experiment and, by using case studies, consider how the many patterns available to palaeoecologists can support model evaluation in a way that moves beyond simplistic pattern-matching and how such models
Experimental model of smoking and simulation of reflux with acid and pepsin in rats.
Zen Junior, José Hélio; Del Negro, André; Colli Neto, José Alexandre; Araujo, Marina Rachel; Altemani, Albina Maria; Andreollo, Nelson Adami
2012-01-01
To develop experimental models to evaluate the effects of hydrochloric acid associated with the pepsin instilled in the mucosa of the upper esophagus and the esophagogastric junction of young male rats Wistar, simulating injury caused by gastroesophageal reflux on the mucosa of aero-digestive tract in humans as well as the action of the risk exposure of mucosa to cigarette smoke. Fifty young male Wistar rats divided in 5 groups with 10 animals each one, respectively simulating pharyngo-laryngeal reflux and gastroesophageal reflux, pharyngo-laryngeal reflux and smoking, smoking only, gastroesophageal reflux and control group. The histopathologic studies no recorded neoplasias, only mild changes and no significant alterations. The hemo-oximetry (carboxyhemoglobin and methemoglobim) and CO2 concentration confirm that the animals were submitted to high intensity of exposure to carcinogens in tobacco and its derivatives. The experimental models were highly efficient, practical, easy to use and economical and can be employed in other similar studies to determine the harmful effects by smoking and reflux.
Comparison of simulation and experimental results for a model aqueous tert-butanol solution
Overduin, S. D.; Patey, G. N.
2017-07-01
Molecular dynamics simulations are used to investigate the behavior of aqueous tert-butanol (TBA) solutions for a range of temperatures, using the CHARMM generalized force field (CGenFF) to model TBA and the TIP4P/2005 or TIP4P-Ew water model. Simulation results for the density, isothermal compressibility, constant pressure heat capacity, and self-diffusion coefficients are in good accord with experimental measurements. Agreement with the experiment is particularly good at low TBA concentration, where experiments have revealed anomalies in a number of thermodynamic properties. Importantly, the CGenFF model does not exhibit liquid-liquid demixing at temperatures between 290 and 320 K (for systems of 32 000 molecules), in contrast with the situation for several other common TBA models [R. Gupta and G. N. Patey, J. Chem. Phys. 137, 034509 (2012)]. However, whereas real water and TBA are miscible at all temperatures where the liquid is stable, we observe some evidence of demixing at 340 K and above. To evaluate the structural properties at low concentrations, we compare with both neutron scattering and recent spectroscopic measurements. This reveals that while the CGenFF model is a definite improvement over other models that have been considered, the TBA molecules still exhibit a tendency to associate at low concentrations that is somewhat stronger than that indicated by experiments. Finally, we discuss the range and decay times of the long-range correlations, providing an indication of the system size and simulation times that are necessary in order to obtain reliable results for certain properties.
International Nuclear Information System (INIS)
Reyes, A.; Henríquez-Vargas, L.; Aravena, R.; Sepúlveda, F.
2015-01-01
Highlights: • Enhancement of paraffin wax thermal conductivity using soft drink can stripes. • Thermal analysis and simulations results agree well with experimental data. • Increase in accumulator thermal efficiencies through addition of external aluminum stripes. • Proposed accumulator allows up to 13,000 kJ of energy storage. - Abstract: Soft drink cans filled with paraffin wax mixed with 7.5% aluminum stripes, obtained from disposable cans, doubled the thermal conductivity of cans filled only with paraffin wax. Promising results obtained in a prototype heat exchanger encouraged the construction of this unit 6 times bigger. We experimentally evaluated and model a heat exchanger for solar energy accumulation, composed by 300 disposable soft drink cans filled with a total of 59.25 kg of paraffin wax mixed with 7.5% aluminum stripes. The effect of adding 2.75 kg of aluminum fins for enhancing heat transfer from the outer surface of the cans to the circulant air was experimentally analyzed. In sunny days, the wax melted completely in about 4 h. The accumulated energy in form of latent heat (about 13,000 kJ) allowed to increase the temperature of 0.040 kg/s of circulant air in at least 20 °C during a period of 2.5 h. For an air mass rate of 0.018 kg/s the period was extended practically to 5 h. The accumulator thermal analysis was presented and a subsequent numerical simulation with Matlab was performed to compare with the experimental results obtaining good agreement specially for higher air mass flow rates. The low cost accumulator presented is of simple construction and will allow extended use of solar energy for applications such as drying processes or household calefaction system.
Bonne, F.; Alamir, M.; Bonnay, P.
2017-02-01
This paper deals with multivariable constrained model predictive control for Warm Compression Stations (WCS). WCSs are subject to numerous constraints (limits on pressures, actuators) that need to be satisfied using appropriate algorithms. The strategy is to replace all the PID loops controlling the WCS with an optimally designed model-based multivariable loop. This new strategy leads to high stability and fast disturbance rejection such as those induced by a turbine or a compressor stop, a key-aspect in the case of large scale cryogenic refrigeration. The proposed control scheme can be used to achieve precise control of pressures in normal operation or to avoid reaching stopping criteria (such as excessive pressures) under high disturbances (such as a pulsed heat load expected to take place in future fusion reactors, expected in the cryogenic cooling systems of the International Thermonuclear Experimental Reactor ITER or the Japan Torus-60 Super Advanced fusion experiment JT-60SA). The paper details the simulator used to validate this new control scheme and the associated simulation results on the SBTs WCS. This work is partially supported through the French National Research Agency (ANR), task agreement ANR-13-SEED-0005.
Directory of Open Access Journals (Sweden)
Guoyan Li
2016-01-01
Full Text Available The gear damage will induce modulation effects in vibration signals. A thorough analysis of modulation sidebands spectral structure is necessary for fault diagnosis of planetary gear set. However, the spectral characteristics are complicated in practice, especially for a multistage planetary gear set which contains close frequency components. In this study, a coupled lateral and torsional dynamic model is established to predict the modulation sidebands of a two-stage compound planetary gear set. An improved potential energy method is used to calculate the time-varying mesh stiffness of each gear pair, and the influence of crack propagation on the mesh stiffness is analyzed. The simulated signals of the gear set are obtained by using Runge-Kutta numerical analysis method. Meanwhile, the sidebands characteristics are summarized to exhibit the modulation effects caused by sun gear damage. At the end, the experimental signals collected from an industrial SD16 planetary gearbox are analyzed to verify the theoretical derivations. The results of experiment agree well with the simulated analysis.
Silva-Ortigoza, R.; Silva-Ortigoza, G.; Hernandez-Guzman, V. M.; Saldana-Gonzalez, G.; Marcelino-Aranda, M.; Marciano-Melchor, M.
2012-01-01
We introduce a dc/dc boost power converter as a didactic prototype intended to support courses on electric circuit analysis experimentally. The corresponding mathematical model is obtained, the converter is designed and an experimental setup is described, constructed and tested. Simplicity of construction as well as low cost of components renders…
International Nuclear Information System (INIS)
Silva-Ortigoza, R; Marciano-Melchor, M; Silva-Ortigoza, G; Hernández-Guzmán, V M; Saldaña-González, G; Marcelino-Aranda, M
2012-01-01
We introduce a dc/dc boost power converter as a didactic prototype intended to support courses on electric circuit analysis experimentally. The corresponding mathematical model is obtained, the converter is designed and an experimental setup is described, constructed and tested. Simplicity of construction as well as low cost of components renders the feasible introduction of this equipment in undergraduate laboratories. (paper)
Energy Technology Data Exchange (ETDEWEB)
Turinsky, Paul J [North Carolina State Univ., Raleigh, NC (United States); Abdel-Khalik, Hany S [North Carolina State Univ., Raleigh, NC (United States); Stover, Tracy E [North Carolina State Univ., Raleigh, NC (United States)
2011-03-01
An optimization technique has been developed to select optimized experimental design specifications to produce data specifically designed to be assimilated to optimize a given reactor concept. Data from the optimized experiment is assimilated to generate posteriori uncertainties on the reactor concept’s core attributes from which the design responses are computed. The reactor concept is then optimized with the new data to realize cost savings by reducing margin. The optimization problem iterates until an optimal experiment is found to maximize the savings. A new generation of innovative nuclear reactor designs, in particular fast neutron spectrum recycle reactors, are being considered for the application of closing the nuclear fuel cycle in the future. Safe and economical design of these reactors will require uncertainty reduction in basic nuclear data which are input to the reactor design. These data uncertainty propagate to design responses which in turn require the reactor designer to incorporate additional safety margin into the design, which often increases the cost of the reactor. Therefore basic nuclear data needs to be improved and this is accomplished through experimentation. Considering the high cost of nuclear experiments, it is desired to have an optimized experiment which will provide the data needed for uncertainty reduction such that a reactor design concept can meet its target accuracies or to allow savings to be realized by reducing the margin required due to uncertainty propagated from basic nuclear data. However, this optimization is coupled to the reactor design itself because with improved data the reactor concept can be re-optimized itself. It is thus desired to find the experiment that gives the best optimized reactor design. Methods are first established to model both the reactor concept and the experiment and to efficiently propagate the basic nuclear data uncertainty through these models to outputs. The representativity of the experiment
[Compared Markov with fractal models by using single-channel experimental and simulation data].
Lan, Tonghan; Wu, Hongxiu; Lin, Jiarui
2006-10-01
The gating mechanical kinetical of ion channels has been modeled as a Markov process. In these models it is assumed that the channel protein has a small number of discrete conformational states and kinetic rate constants connecting these states are constant, the transition rate constants among the states is independent both of time and of the previous channel activity. It is assumed in Liebovitch's fractal model that the channel exists in an infinite number of energy states, consequently, transitions from one conductance state to another would be governed by a continuum of rate constants. In this paper, a statistical comparison is presented of Markov and fractal models of ion channel gating, the analysis is based on single-channel data from ion channel voltage-dependence K+ single channel of neuron cell and simulation data from three-states Markov model.
Load theory behind the wheel: an experimental application of a cognitive model to simulated driving
Murphy, Gillian
2017-01-01
Load Theory is a prominent model of selective attention first proposed over twenty years ago. Load Theory is supported by a great many experimental and neuroimaging studies. There is however, little evidence that Load Theory can be applied to real world attention, though it has great practical potential. Driving, as an everyday task where failures of attention can have profound consequences, stands to benefit from the understanding of selective attention that Load Theory provides. The aim of ...
Experimental Simulation of Flow-Induced Vibration for Developing a Grid-to-Rod Fretting Model
Energy Technology Data Exchange (ETDEWEB)
Lee, Youngho; Kim, Hyungkyu; Kang, Heungseok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2013-05-15
GTRF margin was calculated based on the fuel reliabilities program of operating power plants. But they have not accumulated sufficient experience under challenging operating conditions to be considered proven solutions. In addition, GTRF behaviors were significantly differed according to the plant types, operating condition and fuel types. So, analytical methods to resolve GTRF degradations are considered as difficult procedures for actual application. One of the most important problems is that it is difficult to evaluate the GTRF resistance of new spacer grid under operating power plant condition. Up to now, as a consequence, compliance with the fretting wear limit (typically 10% of the cladding thickness) is checked a posteriori, through post-irradiation examination. Therefore, in this study, rod simulation method for determining GTRF resistance of new spacer grid was proposed with a specially designed wear tester. This simulator enables us to examine the spacer grid shape effect under relatively short development period. In addition, for developing GTRF model, flow-induced vibration (FIV) was measured with different major variables such as GTR clearance, flow rate, etc. Fretting wear tests of nuclear fuel rods (i. e. grid-to-rod fretting) have been performed to examine the flow rate effect by using a specially designed test section with a simulated primary coolant. Based on above results, developed FIV-wear simulator could be effective to examine the spacer grid shape effect with short development period. Further study will be discussed on the GTR clearance effect with various spacer grid shapes.
International Nuclear Information System (INIS)
Wuerz, H.; Arkhipov, N.I.; Bakhtin, V.P.; Konkashbaev, I.; Landman, I.; Safronov, V.M.; Toporkov, D.A.; Zhitlukhin, A.M.
1995-01-01
The high divertor heat load during a tokamak plasma disruption results in sudden evaporation of a thin layer of divertor plate material, which acts as vapor shield and protects the target from further excessive evaporation. Formation and effectiveness of the vapor shield are theoretically modeled and are experimentally analyzed at the 2MK-200 facility under conditions simulating the thermal quench phase of ITER tokamak plasma disruptions. ((orig.))
Sasmal, G. P.; Hochstein, J. I.; Wendl, M. C.; Hardy, T. L.
1991-01-01
A multidimensional computational model of the pressurization process in a slush hydrogen propellant storage tank was developed and its accuracy evaluated by comparison to experimental data measured for a 5 ft diameter spherical tank. The fluid mechanic, thermodynamic, and heat transfer processes within the ullage are represented by a finite-volume model. The model was shown to be in reasonable agreement with the experiment data. A parameter study was undertaken to examine the dependence of the pressurization process on initial ullage temperature distribution and pressurant mass flow rate. It is shown that for a given heat flux rate at the ullage boundary, the pressurization process is nearly independent of initial temperature distribution. Significant differences were identified between the ullage temperature and velocity fields predicted for pressurization of slush and those predicted for pressurization of liquid hydrogen. A simplified model of the pressurization process was constructed in search of a dimensionless characterization of the pressurization process. It is shown that the relationship derived from this simplified model collapses all of the pressure history data generated during this study into a single curve.
Directory of Open Access Journals (Sweden)
Vijay Barethiye
2017-12-01
Full Text Available Modeling dynamic characteristics of an automotive shock absorber is a challenging task due to its complex behavior. In the present paper, the nonparametric and hybrid approach is proposed to represent the nonlinear and hysteresis characteristics of the shock absorber. An experiment is carried out on a car damper utilizing INSTRON to obtain force-velocity characteristics of the shock absorber. The experimental data is used to devise two different models, namely, piecewise linear model and hysteresis model, to capture the damping properties of the absorber and for consequent use in simulations. The complexity involved due to certain physical phenomenon such as oil compressibility, gas entrapment etc. gives rise to hysteresis behavior and the present paper tries to model such behavior with the help of Neural Networks. Finally, a combined (hybrid shock absorber model (including the characteristics of both piecewise linear and hysteresis behavior is developed in Simulink and integrated into a quarter car simulation to verify its feasibility. The results generated by the combined (hybrid model are compared with linear as well as piecewise linear model and the comparison shows that the proposed model substantially a better option to study the vehicle characteristics more accurately and precisely.
DEFF Research Database (Denmark)
Avolio, E.; Federico, S.; Miglietta, M.
2017-01-01
the surface, where the model uncertainties are, usually, smaller than at the surface. A general anticlockwise rotation of the simulated flow with height is found at all levels. The mixing height is overestimated by all schemes and a possible role of the simulated sensible heat fluxes for this mismatching......The sensitivity of boundary layer variables to five (two non-local and three local) planetary boundary-layer (PBL) parameterization schemes, available in the Weather Research and Forecasting (WRF) mesoscale meteorological model, is evaluated in an experimental site in Calabria region (southern...... is investigated. On a single-case basis, significantly better results are obtained when the atmospheric conditions near the measurement site are dominated by synoptic forcing rather than by local circulations. From this study, it follows that the two first order non-local schemes, ACM2 and YSU, are the schemes...
International Nuclear Information System (INIS)
Noroy-Nadal, M.H.
2002-06-01
This memory presents the research concerning the characterization of materials and the Non Destructive Testing (N.D.T) by ultrasonics. The different topics include three steps: modeling, computations and experimental validation. The studied materials concern mainly metals. The memory is divided in four parts. The first one concerns the characterization of materials versus temperature. The determination of the shear modulus G(T) is especially studied for a large temperature range, and around the melting point. The second part is devoted to studies by photothermal devices essentially focused on the modeling of the mechanical displacement and the stress field in coated materials. In this particular field of interest, applications concern either the mechanical characterization of the coating, the defect detection in the structure and finally the evaluation of the coating adhesion. The third section is dedicated to microstructural characterization using acoustic microscopy. The evaluation of crystallographic texture is especially approached, for metallic objects obtained by forming. Before concluding and pointing out some perspectives to this work, the last section concerns the introduction of optimization techniques, applied to the material characterization by acoustic microscopy. (author)
International Nuclear Information System (INIS)
Wang Yong; Salvage, Karen
2005-01-01
A geochemical model is developed for the immobilization of U in the presence of metallic Fe. Zero-valent iron (ZVI) serves as a reducing agent inducing the reductive-precipitation of U, and ZVI corrosion products can serve as absorbing agents for U. The numerical model developed allows the complex interactions of U in solution in differing concentrations to be examined, under variable pH and redox conditions, with or without carbonate, in the presence of ZVI of different size and surface area. It incorporates Fe corrosion, Fe(II) and Fe(III) corrosion product formation, reductive-precipitation of U from the soluble U(VI) valence to the poorly soluble U(IV) valence, adsorption/de-sorption of U onto the Fe oxide corrosion products, and aqueous speciation. The processes of Fe corrosion and reductive precipitation of U are simulated as non-equilibrium, an improvement over other geochemical models. The reductive-precipitation process may use either ZVI or Fe(II) as the reducing agent. The model is calibrated using 3 separate sets of experimental data from published literature that cover a wide range of redox conditions. Sensitivity of the model predictions to variations in input parameters is examined. The simulation results show that the different published experimental results can be explained by different solution chemistries in the studies, specifically O 2 and CO 2 availability and pH, and the amount and surface area of the metallic Fe. With this numerical model the behavior of U in ZVI containing systems over a range of conditions realistic for groundwater can be investigated. By synthesizing observations across several experimental studies, it will lead to a broader understanding of the processes controlling U immobilization under varied geochemical conditions
International Nuclear Information System (INIS)
Lin Chiwen
2001-01-01
This part of the presentation discusses the modelling details required and the simulation techniques available for analyses, facilitating the comparison with the experimental data and providing support for interpretation of the test results. It is organised to cover the following topics: analysis inputs; basic modelling requirements for reactor coolant system; method applicable for reactor cooling system; consideration of damping values and integration time steps; typical analytic models used for analysis of reactor pressure vessel and internals; hydrodynamic mass and fluid damping for the internal analysis; impact elements for fuel analysis; and PEI theorem and its applications. The intention of these topics is to identify the key parameters associated with models of analysis and analytical methods. This should provide proper basis for useful comparison with the test results
International Nuclear Information System (INIS)
Clemmer, R.G.; Land, R.H.; Maroni, V.A.; Mintz, J.M.
1978-01-01
Although some experience has been gained in the design and construction of 0.5 to 5 m 3 /s air-detritiation systems, little information is available on the performance of these systems under realistic conditions. Recently completed studies at ANL have attempted to provide some perspective on this subject. A time-dependent computer model was developed to study the effects of various reaction and soaking mechanisms that could occur in a typically-sized fusion reactor building (approximately 10 5 m 3 ) following a range of tritium releases (2 to 200 g). In parallel with the computer study, a small (approximately 50 liter) test chamber was set up to investigate cleanup characteristics under conditions which could also be simulated with the computer code. Whereas results of computer analyses indicated that only approximately 10 -3 percent of the tritium released to an ambient enclosure should be converted to tritiated water, the bench-scale experiments gave evidence of conversions to water greater than 1%. Furthermore, although the amounts (both calculated and observed) of soaked-in tritium are usually only a very small fraction of the total tritium release, the soaked tritium is significant, in that its continuous return to the enclosure extends the cleanup time beyond the predicted value in the absence of any soaking mechanisms
Modeling, Simulation, Additive Manufacturing, and Experimental Evaluation of Solid and Porous NiTi
Taheri Andani, Mohsen
transformation temperatures of the manufactured parts. To this end both phase transformation and mechanical behavior of the AM parts are studied. Moreover, the application of additive manufacturing to develop NiTi components with desired stiffness by introducing engineered porosity is studied. To this end, a unit cell made of two interconnecting struts is used to generate the CAD files for a series of porous structures with six different levels of porosity in the range of 20% to 82%. Finite element analyses are conducted to examine the stress-strain behavior of the fabricated structures under loading. To validate the simulations, uniaxial compression tests are performed on three NiTi samples with three different levels of porosity (32%, 45%, and 58%). The experimental data closely match with the analytical results. The findings of this study indicate that introducing porosity to a NiTi structure results in a significant drop in the stiffness of the component. These results pave the way for designing porous NiTi structures with the desired level of stiffness.
Energy Technology Data Exchange (ETDEWEB)
Yang, Weibo; Liu, Guangyuan [School of Energy and Power Engineering, Yangzhou University, Yangzhou City (China); Shi, Mingheng; Chen, Zhenqian [School of Energy and Environment, Southeast University, Nanjing City (China)
2009-10-15
Heat transfer around vertical ground heat exchanger (GHE) is a common problem for the design and simulation of ground coupled heat pump (GCHP). In this paper, an updated two-region vertical U-tube GHE analytical model, which is fit for system dynamic simulation of GCHP, is proposed and developed. It divides the heat transfer region of GHE into two parts at the boundary of borehole wall, and the two regions are coupled by the temperature of borehole wall. Both steady and transient heat transfer method are used to analyze the heat transfer process inside and outside borehole, respectively. The transient borehole wall temperature is calculated for the soil region outside borehole by use of a variable heat flux cylindrical source model. As for the region inside borehole, considering the variation of fluid temperature along the borehole length and the heat interference between two adjacent legs of U-tube, a quasi-three dimensional steady-state heat transfer analytical model for the borehole is developed based on the element energy conservation. The implement process of the model used in the dynamic simulation of GCHPs is illuminated in detail and the application calculation example for it is also presented. The experimental validation on the model is performed in a solar-geothermal multifunctional heat pump experiment system with two vertical boreholes and each with a 30 m vertical 1 1/4 in nominal diameter HDPE single U-tube GHE, the results indicate that the calculated fluid outlet temperatures of GHE by the model are agreed well with the corresponding test data and the guess relative error is less than 6%. (author)
Experimental facilities and simulation means
International Nuclear Information System (INIS)
Thomas, J.B.
2009-01-01
This paper and its associated series of slides review the experimental facilities and the simulation means used for the development of nuclear reactors in France. These experimental facilities include installations used for the measurement and qualification of nuclear data (mainly cross-sections) like EOLE reactor and Minerve zero power reactor, installations like material testing reactors, installations dedicated to reactor safety experiments like Cabri reactor, and other installations like accelerators (Jannus accelerator, GANIL for instance) that are complementary to neutron irradiations in experimental reactors. The simulation means rely on a series of advanced computer codes: Tripoli-Apollo for neutron transport, Numodis for irradiation impact on materials, Neptune and Cathare for 2-phase fluid dynamics, Europlexus for mechanical structures, and Pleiades (with Alcyone) for nuclear fuels. (A.C.)
Energy Technology Data Exchange (ETDEWEB)
Khedr, A.; Abdel-Latif, Salwa H. [Nuclear and Radiological Regulatory Authority, Cairo (Egypt); Abdel-Hadi, Eed A. [Benha Univ., Cairo (Egypt). Shobra Faculty of Engineering; D' Auria, F. [Pisa Univ. (Italy)
2016-03-15
In an attempt to understand the built-up of natural circulation in MTR pool type upward flow research reactors after loss of power, an experimental test rig was built to simulate the loop of natural circulation in MTR reactors. The test rig consisting of two vertically oriented branches, in one of them the core is simulated by two rectangular, electrically heated, parallel channels. The other branch simulates the part of the return pipe that participates in the development of core natural circulation. In the first phase of the work, many experimental runs at different conditions of channel's power and branch's initial temperatures are performed. The channel's coolant and surface temperatures were measured. The measurements and their interpretation were published by the first three authors. In the present work the thermal hydraulic behavior of the test rig is complemented by theoretical analysis using RELAP5 Mod 3.3 system code. The analysis consisting of two parts; in the first part RELAP5 model is validated against the measured values and in the second part some of the other not measured hydraulic parameters are predicted and analyzed. The test rig is typically nodalized and an input dick is prepared. In spite of the low pressure of the test rig, the results show that RELAP5 qualitatively predicts the thermal hydraulic behaviour and the accompanied phenomenon of flow inversion of such facilities. Quantitatively, there is a difference between the predicted and measured values especially the channel's surface temperature. This difference may be return to the uncertainties in initial conditions of experimental runs, the position of the thermocouples which buried inside the heat structure, and the heat transfer package in RELAP5.
Tesfay, Hayelom D.
, and Alumina) were conducted. Based on the experimental results, analytical models for UVAG and CG (conventional grinding without ultrasonic vibration) processes were developed. As for the numerical study, an extended finite element method (XFEM) based on Virtual Crack Closure Technique (VCCT) in ABAQUS was used to model the formation of edge chippings both for UVAG and CG processes. The experimental results are compared against the numerical FEA and the analytical models. The experimental, theoretical, and computational simulation results revealed that the edge chipping size of bioceramics can be significantly reduced with the assistance of ultrasonic vibration. The investigation procedures and the results obtained in this dissertation would be used as a reference and practical guidance for choosing reasonable process variables as well as designing mathematical (analytical and numerical) models in manufacturing industries and academic institutions when the edge chippings of brittle materials are expected to be controlled.
Directory of Open Access Journals (Sweden)
Mimoun Maurice
2011-03-01
Full Text Available Abstract Background Controlling airborne contamination is of major importance in burn units because of the high susceptibility of burned patients to infections and the unique environmental conditions that can accentuate the infection risk. In particular the required elevated temperatures in the patient room can create thermal convection flows which can transport airborne contaminates throughout the unit. In order to estimate this risk and optimize the design of an intensive care room intended to host severely burned patients, we have relied on a computational fluid dynamic methodology (CFD. Methods The study was carried out in 4 steps: i patient room design, ii CFD simulations of patient room design to model air flows throughout the patient room, adjacent anterooms and the corridor, iii construction of a prototype room and subsequent experimental studies to characterize its performance iv qualitative comparison of the tendencies between CFD prediction and experimental results. The Electricité De France (EDF open-source software Code_Saturne® (http://www.code-saturne.org was used and CFD simulations were conducted with an hexahedral mesh containing about 300 000 computational cells. The computational domain included the treatment room and two anterooms including equipment, staff and patient. Experiments with inert aerosol particles followed by time-resolved particle counting were conducted in the prototype room for comparison with the CFD observations. Results We found that thermal convection can create contaminated zones near the ceiling of the room, which can subsequently lead to contaminate transfer in adjacent rooms. Experimental confirmation of these phenomena agreed well with CFD predictions and showed that particles greater than one micron (i.e. bacterial or fungal spore sizes can be influenced by these thermally induced flows. When the temperature difference between rooms was 7°C, a significant contamination transfer was observed to
Baran, Timothy M; Foster, Thomas H
2011-08-01
We present a new Monte Carlo model of cylindrical diffusing fibers that is implemented with a graphics processing unit. Unlike previously published models that approximate the diffuser as a linear array of point sources, this model is based on the construction of these fibers. This allows for accurate determination of fluence distributions and modeling of fluorescence generation and collection. We demonstrate that our model generates fluence profiles similar to a linear array of point sources, but reveals axially heterogeneous fluorescence detection. With axially homogeneous excitation fluence, approximately 90% of detected fluorescence is collected by the proximal third of the diffuser for μ(s)'∕μ(a) = 8 in the tissue and 70 to 88% is collected in this region for μ(s)'∕μ(a) = 80. Increased fluorescence detection by the distal end of the diffuser relative to the center section is also demonstrated. Validation of these results was performed by creating phantoms consisting of layered fluorescent regions. Diffusers were inserted into these layered phantoms and fluorescence spectra were collected. Fits to these spectra show quantitative agreement between simulated fluorescence collection sensitivities and experimental results. These results will be applicable to the use of diffusers as detectors for dosimetry in interstitial photodynamic therapy.
[Animal experimentation, computer simulation and surgical research].
Carpentier, Alain
2009-11-01
We live in a digital world In medicine, computers are providing new tools for data collection, imaging, and treatment. During research and development of complex technologies and devices such as artificial hearts, computer simulation can provide more reliable information than experimentation on large animals. In these specific settings, animal experimentation should serve more to validate computer models of complex devices than to demonstrate their reliability.
DEFF Research Database (Denmark)
Heydorn, S; Menné, T; Andersen, K E
2003-01-01
previously diagnosed with hand eczema to explore whether immersion of fingers in a solution with or without the patch-test-positive fragrance allergen would cause or exacerbate hand eczema on the exposed finger. The study was double blinded and randomized. All participants had a positive patch test to either...... hydroxycitronellal or Lyral (hydroxyisohexyl 3-cyclohexene carboxaldehyde). Each participant immersed a finger from each hand, once a day, in a solution containing the fragrance allergen or placebo. During the first 2 weeks, the concentration of fragrance allergen in the solution was low (approximately 10 p...... meter. 3 of 15 hand eczema patients developed eczema on the finger immersed in the fragrance-containing solution, 3 of 15 on the placebo finger and 3 of 15 on both fingers. Using this experimental exposure model simulating real-life exposure, we found no association between immersion of a finger...
Ma, Baoshun; Ruwet, Vincent; Corieri, Patricia; Theunissen, Raf; Riethmuller, Michel; Darquenne, Chantal
2009-05-01
Accurate modeling of air flow and aerosol transport in the alveolated airways is essential for quantitative predictions of pulmonary aerosol deposition. However, experimental validation of such modeling studies has been scarce. The objective of this study is to validate CFD predictions of flow field and particle trajectory with experiments within a scaled-up model of alveolated airways. Steady flow (Re = 0.13) of silicone oil was captured by particle image velocimetry (PIV), and the trajectories of 0.5 mm and 1.2 mm spherical iron beads (representing 0.7 to 14.6 mum aerosol in vivo) were obtained by particle tracking velocimetry (PTV). At twelve selected cross sections, the velocity profiles obtained by CFD matched well with those by PIV (within 1.7% on average). The CFD predicted trajectories also matched well with PTV experiments. These results showed that air flow and aerosol transport in models of human alveolated airways can be simulated by CFD techniques with reasonable accuracy.
Jefferson, A.; Avellaneda, P. M.; Jarden, K. M.; Turner, V. K.; Grieser, J.
2016-12-01
Distributed green infrastructure approaches to stormwater management that can be retrofit into existing development are of growing interest, but questions remain about their effectiveness at the watershed-scale. In suburban northeastern Ohio, homeowners on a residential street with 55% impervious surface were given the opportunity for free rain barrels, rain gardens, and bioretention cells. Of 163 parcels, only 22 owners (13.5%) chose to participate, despite intense outreach efforts. After pre-treatment monitoring, 37 rain barrels, 7 rain gardens, and 16 street-side bioretention cells were installed in 2013-2014. Using a paired watershed approach, a reduction in up to 33% of peak flow and 40% of total runoff volume per storm was measured in the storm sewer. Using the monitoring data, a calibrated and validated SWMM model was built to explore the long-term effectiveness of the green infrastructure against a wider range of hydrological conditions. Model results confirm the effectiveness of green infrastructure in reducing surface runoff and increasing infiltration and evaporation. Based on 20 years of historical precipitation data, the model shows that the green infrastructure is capable of reducing flows by >40% at the 1, 2, and 5 year return period, suggesting some resilience to projected increases in precipitation intensity in a changing climate. Further, in this project, more benefit is derived from the street-side bioretention cells than from the rain barrels and gardens that treat rooftop runoff. Substantial hydrological gains were achieved despite low homeowner participation. Surveys indicate that many residents viewed stormwater as the city's problem and had negative perceptions of green infrastructure, despite slightly pro-environment values generally. Overall, this study demonstrates green infrastructure's hydrological effectiveness but raises challenging questions about overcoming social barriers retrofits at the neighborhood scale.
International Nuclear Information System (INIS)
Wuerz, H.; Arkhipov, N.I.; Bakhin, V.P.; Goel, B.; Hoebel, W.; Konkashbaev, I.; Landman, I.; Piazza, G.; Safronov, V.M.; Sherbakov, A.R.; Toporkov, D.A.; Zhitlukhin, A.M.
1994-01-01
The high divertor heat load during a tokamak plasma disruption results in sudden evaporation of a thin layer of divertor plate material, which acts as vapor shield and protects the target from further excessive evaporation. Formation and effectiveness of the vapor shield are theoretically modeled and experimentally investigated at the 2MK-200 facility under conditions simulating the thermal quench phase of ITER tokamak plasma disruptions. In the optical wavelength range C II, C III, C IV emission lines for graphite, Cu I, Cu II lines for copper and continuum radiation for tungsten samples are observed in the target plasma. The plasma expands along the magnetic field lines with velocities of (4±1)x10 6 cm/s for graphite and 10 5 cm/s for copper. Modeling was done with a radiation hydrodynamics code in one-dimensional planar geometry. The multifrequency radiation transport is treated in flux limited diffusion and in forward reverse transport approximation. In these first modeling studies the overall shielding efficiency for carbon and tungsten defined as ratio of the incident energy and the vaporization energy for power densities of 10 MW/cm 2 exceeds a factor of 30. The vapor shield is established within 2 μs, the power fraction to the target after 10 μs is below 3% and reaches in the stationary state after about 20 μs a value of around 1.5%. ((orig.))
International Nuclear Information System (INIS)
Lelong, Franck
2010-01-01
In a pressurized water reactor (PWR), during a Loss Of Coolant Accident (LOCA), liquid water evaporates and the fuel assemblies are not cooled anymore; as a consequence, the temperature rises to such an extent that some parts of the fuel assemblies can be deformed resulting in 'ballooned regions'. When reflooding occurs, the cooling of these partially blocked parts of the fuel assemblies will depend on the coolant flow that is a mixture of overheated vapour and under-saturated droplets. The aim of this thesis is to study the heat transfer between droplets and hot walls of the fuel rods. In this purpose, an experimental device has been designed in accordance with droplets and wall features (droplet velocity and diameter, wall temperature) representative of LOCA conditions. The cooling of a hot Nickel disk, previously heated by induction, is cooled down by a stream of monodispersed droplet. The rear face temperature profiles are measured by infrared thermography. Then, the estimation of wall heat flux is performed by an inverse conduction technique from these infrared images. The effect of droplet dynamical properties (diameter, velocity) on the heat flux is studied. These experimental data allow us to validate an analytical model of heat exchange between droplet and hot slab. This model is based on combined dynamical and thermal considerations. On the one hand, the droplet dynamics is considered through a spring analogy in order to evaluate the evolution of droplet features such as the spreading diameter when the droplet is squeezed over the hot surface. On the other hand, thermal parameters, such as the thickness of the vapour cushion beneath the droplet, are determined from an energy balance. In the short term, this model will be integrated in a CFD code (named NEPTUNE-CFD) to simulate the cooling of a reactor core during a LOCA, taking into account the droplet/wall heat exchange. (author)
Energy Technology Data Exchange (ETDEWEB)
Al Cheikh Kassem, N.; Miriel, J.; Roux, A. [Institut National des Sciences Appliquees (INSA), 35 - Rennes (France)
1993-12-31
This work presents a simulation model of sensible and latent heat storage in the soil of an agricultural greenhouse. Results recorded by the laboratory device of grounded storage and thermo-physic parameter values of soil experimentally obtained by a three rod thermal shock probe are used for checking the simulation model and thus assessing the performance of such a system and the coupling between the greenhouse and the storage. (Authors). 3 refs., 6 figs.
Law, R. M.; Peters, W.; Roedenbeck, C.; Aulagnier, C.; Baker, I.; Bergmann, D. J.; Bousquet, P.; Brandt, J.; Bruhwiler, L.; Cameron-Smith, P. J.; Christensen, J. H.; Delage, F.; Denning, A. S.; Fan, S.; Geels, C.; Houweling, S.; Imasu, R.; Karstens, U.; Kawa, S. R.; Kleist, J.; Krol, M. C.; Lin, S. -J.; Lokupitiya, R.; Maki, T.; Maksyutov, S.; Niwa, Y.; Onishi, R.; Parazoo, N.; Patra, P. K.; Pieterse, G.; Rivier, L.; Satoh, M.; Serrar, S.; Taguchi, S.; Takigawa, M.; Vautard, R.; Vermeulen, A. T.; Zhu, Z.
2008-01-01
[1] A forward atmospheric transport modeling experiment has been coordinated by the TransCom group to investigate synoptic and diurnal variations in CO2. Model simulations were run for biospheric, fossil, and air-sea exchange of CO2 and for SF6 and radon for 2000-2003. Twenty-five models or model
Law, R. M.; Peters, W.; RöDenbeck, C.; Aulagnier, C.; Baker, I.; Bergmann, D. J.; Bousquet, P.; Brandt, J.; Bruhwiler, L.; Cameron-Smith, P. J.; Christensen, J. H.; Delage, F.; Denning, A. S.; Fan, S.; Geels, C.; Houweling, S.; Imasu, R.; Karstens, U.; Kawa, S. R.; Kleist, J.; Krol, M. C.; Lin, S.-J.; Lokupitiya, R.; Maki, T.; Maksyutov, S.; Niwa, Y.; Onishi, R.; Parazoo, N.; Patra, P. K.; Pieterse, G.; Rivier, L.; Satoh, M.; Serrar, S.; Taguchi, S.; Takigawa, M.; Vautard, R.; Vermeulen, A. T.; Zhu, Z.
2008-01-01
A forward atmospheric transport modeling experiment has been coordinated by the TransCom group to investigate synoptic and diurnal variations in CO2. Model simulations were run for biospheric, fossil, and air-sea exchange of CO2 and for SF6 and radon for 2000-2003. Twenty-five models or model
Computer Modeling and Simulation
Energy Technology Data Exchange (ETDEWEB)
Pronskikh, V. S. [Fermilab
2014-05-09
Verification and validation of computer codes and models used in simulation are two aspects of the scientific practice of high importance and have recently been discussed by philosophers of science. While verification is predominantly associated with the correctness of the way a model is represented by a computer code or algorithm, validation more often refers to model’s relation to the real world and its intended use. It has been argued that because complex simulations are generally not transparent to a practitioner, the Duhem problem can arise for verification and validation due to their entanglement; such an entanglement makes it impossible to distinguish whether a coding error or model’s general inadequacy to its target should be blamed in the case of the model failure. I argue that in order to disentangle verification and validation, a clear distinction between computer modeling (construction of mathematical computer models of elementary processes) and simulation (construction of models of composite objects and processes by means of numerical experimenting with them) needs to be made. Holding on to that distinction, I propose to relate verification (based on theoretical strategies such as inferences) to modeling and validation, which shares the common epistemology with experimentation, to simulation. To explain reasons of their intermittent entanglement I propose a weberian ideal-typical model of modeling and simulation as roles in practice. I suggest an approach to alleviate the Duhem problem for verification and validation generally applicable in practice and based on differences in epistemic strategies and scopes
Ewert, F.; Rodriguez, D.; Jamieson, P.; Semenov, M.A.; Mitchell, R.A.C.; Goudriaan, J.; Porter, J.R.; Kimball, B.A.; Pinter, P.J.; Manderscheid, R.; Weigel, H.J.; Fangmeier, A.; Fereres, E.; Villalobos, F.
2002-01-01
Effects of increasing carbon dioxide concentration [CO2] on wheat vary depending on water supply and climatic conditions, which are difficult to estimate. Crop simulation models are often used to predict the impact of global atmospheric changes on food production. However, models have rarely been
DEFF Research Database (Denmark)
Conrad, Finn; Pobedza, J.; Sobczyk, A.
2003-01-01
The paper presents experimental-based modelling, simulation, analysis and design of water hydraulic actuators for motion control of machines, lifts, cranes and robots. The contributions includes results from on-going research projects on fluid power and mechatronics based on tap water hydraulic...
International Nuclear Information System (INIS)
Hernandez Gonzalez, Francisco Alberto
2016-01-01
The Breeder Units contains pebble beds of lithium orthosilicate (Li_4SiO_4) as tritium breeder material and beryllium as neutron multiplier. In this dissertation a closed validation strategy for the thermo-mechanical validation of the Breeder Units has been developed. This strategy is based on the development of dedicated testing and modeling tools, which are needed for the qualification of the thermo-mechanical functionality of these components in an out-of-pile experimental campaign. The neutron flux in the Breeder Units induces a nonhomogeneous volumetric heating in the pebble beds that must be mimicked in an out-of-pile experiment with an external heating system minimizing the intrusion in the pebble beds. Therefore, a heater system that simulates this volumetric heating has been developed. This heater system is based on ohmic heating and linear heater elements, which approximates the point heat sources of the granular material by linear sources. These linear sources represent ''linear pebbles'' in discrete locations close enough to relatively reproduce the thermal gradients occurring in the functional materials. The heater concept has been developed for the Li_4SiO_4 and it is based on a hexagonal matrix arrangement of linear and parallel heater elements of diameter 1 mm separated by 7 mm. A set of uniformly distributed thermocouples in the transversal and longitudinal direction in the pebble bed midplane allows a 2D temperature reconstruction of that measurement plane by means of biharmonic spline interpolation. This heating system has been implemented in a relevant Breeder Unit region and its proof-of-concept has been tested in a PRE-test Mock-Up eXperiment (PREMUX) that has been designed and constructed in the frame of this dissertation. The packing factor of the pebble bed with and without the heating system does not show significant differences, giving an indirect evidence of the low intrusion of the system. Such low intrusion has been confirmed by in
Energy Technology Data Exchange (ETDEWEB)
Hernandez Gonzalez, Francisco Alberto
2016-10-14
The Breeder Units contains pebble beds of lithium orthosilicate (Li{sub 4}SiO{sub 4}) as tritium breeder material and beryllium as neutron multiplier. In this dissertation a closed validation strategy for the thermo-mechanical validation of the Breeder Units has been developed. This strategy is based on the development of dedicated testing and modeling tools, which are needed for the qualification of the thermo-mechanical functionality of these components in an out-of-pile experimental campaign. The neutron flux in the Breeder Units induces a nonhomogeneous volumetric heating in the pebble beds that must be mimicked in an out-of-pile experiment with an external heating system minimizing the intrusion in the pebble beds. Therefore, a heater system that simulates this volumetric heating has been developed. This heater system is based on ohmic heating and linear heater elements, which approximates the point heat sources of the granular material by linear sources. These linear sources represent ''linear pebbles'' in discrete locations close enough to relatively reproduce the thermal gradients occurring in the functional materials. The heater concept has been developed for the Li{sub 4}SiO{sub 4} and it is based on a hexagonal matrix arrangement of linear and parallel heater elements of diameter 1 mm separated by 7 mm. A set of uniformly distributed thermocouples in the transversal and longitudinal direction in the pebble bed midplane allows a 2D temperature reconstruction of that measurement plane by means of biharmonic spline interpolation. This heating system has been implemented in a relevant Breeder Unit region and its proof-of-concept has been tested in a PRE-test Mock-Up eXperiment (PREMUX) that has been designed and constructed in the frame of this dissertation. The packing factor of the pebble bed with and without the heating system does not show significant differences, giving an indirect evidence of the low intrusion of the system. Such
International Nuclear Information System (INIS)
Chason, E; Chan, W L
2009-01-01
Kinetic Monte Carlo simulations model the evolution of surfaces during low energy ion bombardment using atomic level mechanisms of defect formation, recombination and surface diffusion. Because the individual kinetic processes are completely determined, the resulting morphological evolution can be directly compared with continuum models based on the same mechanisms. We present results of simulations based on a curvature-dependent sputtering mechanism and diffusion of mobile surface defects. The results are compared with a continuum linear instability model based on the same physical processes. The model predictions are found to be in good agreement with the simulations for predicting the early-stage morphological evolution and the dependence on processing parameters such as the flux and temperature. This confirms that the continuum model provides a reasonable approximation of the surface evolution from multiple interacting surface defects using this model of sputtering. However, comparison with experiments indicates that there are many features of the surface evolution that do not agree with the continuum model or simulations, suggesting that additional mechanisms are required to explain the observed behavior.
Directory of Open Access Journals (Sweden)
Iulian Rosu
2018-04-01
Full Text Available The aim of this study is to investigate the thermal evolution of an aircraft tire rolling at high velocities up to take off values. As this kind of experiment is difficult to realize on a real runway, experimental tests were realized on aircraft tires rolling on a steel drum. The rotating drum facility allows to apply variable velocities beyond the take off limits, at fixed skidding angles and loadings. The rolling conditions, vertical loading, velocity and cornering conditions were adopted to correspond to the real conditions of an aircraft tire running or skidding on a flat runway. In the experimental part, the influence of skidding angle, velocity and loading on the thermal evolution of the tire tread were investigated. The thermo-mechanical finite element analysis of a pneumatic radial tire structure was performed taking into account the hyper-viscoelastic rubber behavior, with heating mechanisms developed by the inelastic deformation and by friction. Three-dimensional finite element simulations of an aircraft tire rolling on a steel drum were carried out using Abaqus/Standard finite element solver. The comparison of the temperature distribution on the tire tread between numerical results and the experimental data shows the same overall tendencies. The good correlation between numerical and experimental data shows that numerical simulation could predict the thermal evolution of the tire in critical situations. The authors would like to mention that for confidentiality reason, certain numerical data could not be revealed.
Heydorn, S; Menné, T; Andersen, K E; Bruze, M; Svedman, C; Basketter, D; Johansen, J D
2003-06-01
Recently, we showed that 10 x 2% of consecutively patch-tested hand eczema patients had a positive patch test to a selection of fragrances containing fragrances relevant to hand exposure. In this study, we used repeated skin exposure to a patch test-positive fragrance allergen in patients previously diagnosed with hand eczema to explore whether immersion of fingers in a solution with or without the patch-test-positive fragrance allergen would cause or exacerbate hand eczema on the exposed finger. The study was double blinded and randomized. All participants had a positive patch test to either hydroxycitronellal or Lyral (hydroxyisohexyl 3-cyclohexene carboxaldehyde). Each participant immersed a finger from each hand, once a day, in a solution containing the fragrance allergen or placebo. During the first 2 weeks, the concentration of fragrance allergen in the solution was low (approximately 10 p.p.m.), whilst during the following 2 weeks, the concentration was relatively high (approximately 250 p.p.m.), imitating real-life exposure to a household product like dishwashing liquid diluted in water and the undiluted product, respectively. Evaluation was made using a clinical scale and laser Doppler flow meter. 3 of 15 hand eczema patients developed eczema on the finger immersed in the fragrance-containing solution, 3 of 15 on the placebo finger and 3 of 15 on both fingers. Using this experimental exposure model simulating real-life exposure, we found no association between immersion of a finger in a solution containing fragrance and development of clinically visible eczema on the finger in 15 participants previously diagnosed with hand eczema and with a positive patch test to the fragrance in question.
Experimental Modeling of Dynamic Systems
DEFF Research Database (Denmark)
Knudsen, Morten Haack
2006-01-01
An engineering course, Simulation and Experimental Modeling, has been developed that is based on a method for direct estimation of physical parameters in dynamic systems. Compared with classical system identification, the method appears to be easier to understand, apply, and combine with physical...
Directory of Open Access Journals (Sweden)
Jennifer A Nichols
Full Text Available The utility of biomechanical models and simulations to examine clinical problems is currently limited by the need for extensive amounts of experimental data describing how a given procedure or disease affects the musculoskeletal system. Methods capable of predicting how individual biomechanical parameters are altered by surgery are necessary for the efficient development of surgical simulations. In this study, we evaluate to what extent models based on limited amounts of quantitative data can be used to predict how surgery influences muscle moment arms, a critical parameter that defines how muscle force is transformed into joint torque. We specifically examine proximal row carpectomy and scaphoid-excision four-corner fusion, two common surgeries to treat wrist osteoarthritis. Using models of these surgeries, which are based on limited data and many assumptions, we perform simulations to formulate a hypothesis regarding how these wrist surgeries influence muscle moment arms. Importantly, the hypothesis is based on analysis of only the primary wrist muscles. We then test the simulation-based hypothesis using a cadaveric experiment that measures moment arms of both the primary wrist and extrinsic thumb muscles. The measured moment arms of the primary wrist muscles are used to verify the hypothesis, while those of the extrinsic thumb muscles are used as cross-validation to test whether the hypothesis is generalizable. The moment arms estimated by the models and measured in the cadaveric experiment both indicate that a critical difference between the surgeries is how they alter radial-ulnar deviation versus flexion-extension moment arms at the wrist. Thus, our results demonstrate that models based on limited quantitative data can provide novel insights. This work also highlights that synergistically utilizing simulation and experimental methods can aid the design of experiments and make it possible to test the predictive limits of current computer
Simulation - modeling - experiment
International Nuclear Information System (INIS)
2004-01-01
After two workshops held in 2001 on the same topics, and in order to make a status of the advances in the domain of simulation and measurements, the main goals proposed for this workshop are: the presentation of the state-of-the-art of tools, methods and experiments in the domains of interest of the Gedepeon research group, the exchange of information about the possibilities of use of computer codes and facilities, about the understanding of physical and chemical phenomena, and about development and experiment needs. This document gathers 18 presentations (slides) among the 19 given at this workshop and dealing with: the deterministic and stochastic codes in reactor physics (Rimpault G.); MURE: an evolution code coupled with MCNP (Meplan O.); neutronic calculation of future reactors at EdF (Lecarpentier D.); advance status of the MCNP/TRIO-U neutronic/thermal-hydraulics coupling (Nuttin A.); the FLICA4/TRIPOLI4 thermal-hydraulics/neutronics coupling (Aniel S.); methods of disturbances and sensitivity analysis of nuclear data in reactor physics, application to VENUS-2 experimental reactor (Bidaud A.); modeling for the reliability improvement of an ADS accelerator (Biarotte J.L.); residual gas compensation of the space charge of intense beams (Ben Ismail A.); experimental determination and numerical modeling of phase equilibrium diagrams of interest in nuclear applications (Gachon J.C.); modeling of irradiation effects (Barbu A.); elastic limit and irradiation damage in Fe-Cr alloys: simulation and experiment (Pontikis V.); experimental measurements of spallation residues, comparison with Monte-Carlo simulation codes (Fallot M.); the spallation target-reactor coupling (Rimpault G.); tools and data (Grouiller J.P.); models in high energy transport codes: status and perspective (Leray S.); other ways of investigation for spallation (Audoin L.); neutrons and light particles production at intermediate energies (20-200 MeV) with iron, lead and uranium targets (Le Colley F
Jia, Bing
2014-03-01
A comb-shaped chaotic region has been simulated in multiple two-dimensional parameter spaces using the Hindmarsh—Rose (HR) neuron model in many recent studies, which can interpret almost all of the previously simulated bifurcation processes with chaos in neural firing patterns. In the present paper, a comb-shaped chaotic region in a two-dimensional parameter space was reproduced, which presented different processes of period-adding bifurcations with chaos with changing one parameter and fixed the other parameter at different levels. In the biological experiments, different period-adding bifurcation scenarios with chaos by decreasing the extra-cellular calcium concentration were observed from some neural pacemakers at different levels of extra-cellular 4-aminopyridine concentration and from other pacemakers at different levels of extra-cellular caesium concentration. By using the nonlinear time series analysis method, the deterministic dynamics of the experimental chaotic firings were investigated. The period-adding bifurcations with chaos observed in the experiments resembled those simulated in the comb-shaped chaotic region using the HR model. The experimental results show that period-adding bifurcations with chaos are preserved in different two-dimensional parameter spaces, which provides evidence of the existence of the comb-shaped chaotic region and a demonstration of the simulation results in different two-dimensional parameter spaces in the HR neuron model. The results also present relationships between different firing patterns in two-dimensional parameter spaces.
International Nuclear Information System (INIS)
Jia Bing
2014-01-01
A comb-shaped chaotic region has been simulated in multiple two-dimensional parameter spaces using the Hindmarsh—Rose (HR) neuron model in many recent studies, which can interpret almost all of the previously simulated bifurcation processes with chaos in neural firing patterns. In the present paper, a comb-shaped chaotic region in a two-dimensional parameter space was reproduced, which presented different processes of period-adding bifurcations with chaos with changing one parameter and fixed the other parameter at different levels. In the biological experiments, different period-adding bifurcation scenarios with chaos by decreasing the extra-cellular calcium concentration were observed from some neural pacemakers at different levels of extra-cellular 4-aminopyridine concentration and from other pacemakers at different levels of extra-cellular caesium concentration. By using the nonlinear time series analysis method, the deterministic dynamics of the experimental chaotic firings were investigated. The period-adding bifurcations with chaos observed in the experiments resembled those simulated in the comb-shaped chaotic region using the HR model. The experimental results show that period-adding bifurcations with chaos are preserved in different two-dimensional parameter spaces, which provides evidence of the existence of the comb-shaped chaotic region and a demonstration of the simulation results in different two-dimensional parameter spaces in the HR neuron model. The results also present relationships between different firing patterns in two-dimensional parameter spaces
Directory of Open Access Journals (Sweden)
Wefstaedt Patrick
2009-11-01
Full Text Available Abstract Background Among other causes the long-term result of hip prostheses in dogs is determined by aseptic loosening. A prevention of prosthesis complications can be achieved by an optimization of the tribological system which finally results in improved implant duration. In this context a computerized model for the calculation of hip joint loadings during different motions would be of benefit. In a first step in the development of such an inverse dynamic multi-body simulation (MBS- model we here present the setup of a canine hind limb model applicable for the calculation of ground reaction forces. Methods The anatomical geometries of the MBS-model have been established using computer tomography- (CT- and magnetic resonance imaging- (MRI- data. The CT-data were collected from the pelvis, femora, tibiae and pads of a mixed-breed adult dog. Geometric information about 22 muscles of the pelvic extremity of 4 mixed-breed adult dogs was determined using MRI. Kinematic and kinetic data obtained by motion analysis of a clinically healthy dog during a gait cycle (1 m/s on an instrumented treadmill were used to drive the model in the multi-body simulation. Results and Discussion As a result the vertical ground reaction forces (z-direction calculated by the MBS-system show a maximum deviation of 1.75%BW for the left and 4.65%BW for the right hind limb from the treadmill measurements. The calculated peak ground reaction forces in z- and y-direction were found to be comparable to the treadmill measurements, whereas the curve characteristics of the forces in y-direction were not in complete alignment. Conclusion In conclusion, it could be demonstrated that the developed MBS-model is suitable for simulating ground reaction forces of dogs during walking. In forthcoming investigations the model will be developed further for the calculation of forces and moments acting on the hip joint during different movements, which can be of help in context with the in
International Nuclear Information System (INIS)
Davidson, Sean R H; Sherar, Michael D
2003-01-01
Urethral cooling catheters are used to prevent thermal damage to the urethra during thermal therapy of the prostate. Quantification of a catheter's heat transfer characteristics is necessary for prediction of the catheter's influence on the temperature and thermal dose distribution in periurethral tissue. Two cooling catheters with different designs were examined: the Dornier Urowave catheter and a prototype device from BSD Medical Corp. A convection coefficient, h, was used to characterize the cooling ability of each catheter. The value of the convection coefficient (h = 330 W m -2 deg C -1 for the Dornier catheter, h = 160 W m -2 deg C -1 for the BSD device) was obtained by comparing temperatures measured in a tissue-equivalent phantom material to temperatures predicted by a finite element method simulation of the phantom experiments. The coefficient was found to be insensitive to the rate of coolant flow inside the catheter between 40 and 120 ml min -1 . The convection coefficient method for modelling urethral catheters was incorporated into simulations of microwave heating of the prostate. Results from these simulations indicate that the Dornier device is significantly more effective than the BSD catheter at cooling the tissue surrounding the urethra
Directory of Open Access Journals (Sweden)
Huamu Xie
2016-10-01
Full Text Available High-average-current, high-brightness electron sources have important applications, such as in high-repetition-rate free-electron lasers, or in the electron cooling of hadrons. Bialkali photocathodes are promising high-quantum-efficiency (QE cathode materials, while superconducting rf (SRF electron guns offer continuous-mode operation at high acceleration, as is needed for high-brightness electron sources. Thus, we must have a comprehensive understanding of the performance of bialkali photocathode at cryogenic temperatures when they are to be used in SRF guns. To remove the heat produced by the radio-frequency field in these guns, the cathode should be cooled to cryogenic temperatures. We recorded an 80% reduction of the QE upon cooling the K_{2}CsSb cathode from room temperature down to the temperature of liquid nitrogen in Brookhaven National Laboratory (BNL’s 704 MHz SRF gun. We conducted several experiments to identify the underlying mechanism in this reduction. The change in the spectral response of the bialkali photocathode, when cooled from room temperature (300 K to 166 K, suggests that a change in the ionization energy (defined as the energy gap from the top of the valence band to vacuum level is the main reason for this reduction. We developed an analytical model of the process, based on Spicer’s three-step model. The change in ionization energy, with falling temperature, gives a simplified description of the QE’s temperature dependence. We also developed a 2D Monte Carlo code to simulate photoemission that accounts for the wavelength-dependent photon absorption in the first step, the scattering and diffusion in the second step, and the momentum conservation in the emission step. From this simulation, we established a correlation between ionization energy and reduction in the QE. The simulation yielded results comparable to those from the analytical model. The simulation offers us additional capabilities such as calculation
PEMFC modeling and experimental validation
Energy Technology Data Exchange (ETDEWEB)
Vargas, J.V.C. [Federal University of Parana (UFPR), Curitiba, PR (Brazil). Dept. of Mechanical Engineering], E-mail: jvargas@demec.ufpr.br; Ordonez, J.C.; Martins, L.S. [Florida State University, Tallahassee, FL (United States). Center for Advanced Power Systems], Emails: ordonez@caps.fsu.edu, martins@caps.fsu.edu
2009-07-01
In this paper, a simplified and comprehensive PEMFC mathematical model introduced in previous studies is experimentally validated. Numerical results are obtained for an existing set of commercial unit PEM fuel cells. The model accounts for pressure drops in the gas channels, and for temperature gradients with respect to space in the flow direction, that are investigated by direct infrared imaging, showing that even at low current operation such gradients are present in fuel cell operation, and therefore should be considered by a PEMFC model, since large coolant flow rates are limited due to induced high pressure drops in the cooling channels. The computed polarization and power curves are directly compared to the experimentally measured ones with good qualitative and quantitative agreement. The combination of accuracy and low computational time allow for the future utilization of the model as a reliable tool for PEMFC simulation, control, design and optimization purposes. (author)
Directory of Open Access Journals (Sweden)
Pedro J. Martínez
2017-09-01
Full Text Available A dedicated outdoor air system (DOAS can be designed to supply 100% of the outside air and meet the latent load of the room with dry air. The objectives of this study were to develop a model of a DOAS equipped with a desiccant wheel and a vapor-compression refrigeration system, build a prototype, validate the model with experimental data, and gain knowledge about the system operation. The test facility was designed with the desiccant wheel downstream of the cooling coil to take advantage of the operating principles of cooling coils and desiccants. A model of the DOAS was developed in the TRNSYS environment. The root mean standard error (RMSE was used for model validation by comparing the measured air and refrigerant properties with the corresponding calculated values. The results obtained with the developed model showed that the DOAS was able to maintain an indoor humidity ratio depending on outdoor conditions. Laboratory tests were also used to investigate the effect of changes in the regeneration air temperature and the process airflow rate on the process air humidity ratio at the outlet of the wheel. The results are consistent with the technical literature.
International Nuclear Information System (INIS)
Mikrenska, M.; Koulev, P.; Renard, J.-B.; Hadamcik, E.; Worms, J.-C.
2006-01-01
The Direct Simulation Monte Carlo (DSMC) model is presented for three-dimensional single scattering of natural light by suspended, randomly oriented, optically homogeneous and isotropic, rounded and stochastically rough cubic particles. The modelled particles have large size parameter that allows geometric optics approximation to be used. The proposed computational model is simple and flexible. It is tested by comparison with known geometric optics solution for a perfect cube and Lorenz-Mie solution for a sphere, as extreme cases of the class of rounded cubes. Scattering and polarization properties of particles with various geometrical and optical characteristics are examined. The experimental study of real NaCl crystals with new Progra 2 instrument in microgravity conditions is conducted. The experimental and computed polarization and brightness phase curves are compared
Directory of Open Access Journals (Sweden)
Jorge Flávio Cazé B. da Costa Silva
2007-12-01
Full Text Available In this study, two hydrological models to estimate soil losses and sediment yield due to sheet and channel erosion, at the basin outlet, are applied to Guaraíra River Experimental Basin, located in Paraíba State, northeastern Brazil. The soil erosion models are (a the classical Universal Soil Loss Equation (USLE, which is used to simulate annual and monthly soil losses; and (b Kineros model, which is used to simulate the sediment yield within the basin. Kineros model is a physically-based distributed model that uses a cascade of planes and channels to represent the basin and to describe the processes of interception, infiltration, surface runoff and erosion within the basin. The USLE is computed using land use, soil erodibility, topographic digital maps, as well as observed rainfall data. It was found that Guaraíra river experimental basin has a low potential for soil losses; however, specific areas which are susceptible to the erosion process in the basin could be detected by the modeling techniques coupled to a GIS (Geographic Information System.
Quantitative comparison between simulated and experimental FCC rolling textures
DEFF Research Database (Denmark)
Wronski, M.; Wierzbanowski, K.; Leffers, Torben
2015-01-01
The degree of similarity between simulated and experimental fcc rolling textures is characterized by a single scalar parameter. The textures are simulated with a relatively simple and efficient 1-point model which allows us to vary the strength of the interaction between the grains and the surrou...
International Nuclear Information System (INIS)
Guerrero-Rodríguez, N.F.; Rey-Boué, Alexis B.
2014-01-01
Highlights: • A MSOGI-FLL is used to detect the frequency. • A PR harmonic-compensator is used. • Grid-connected PV system insensitive to harmonic pollution. • RTDS reinforced the final validation of the control algorithms. • Several algorithms are combined in this paper. - Abstract: The large number of Photovoltaic plants and its utilization as agents of a Distributed Generation Systems justified the increasing efforts towards the optimal design of the overall grid-connected System. In a Distributed Generation environment the low voltage 3-phase utility grid could be affected by some disturbances such as voltage unbalanced, variations of frequency and harmonics distortion and it is mandatory that the control algorithms used in the inverter can be able to maintain the power flow between the renewable agent and the low voltage 3-phase utility grid; in addition a unitary power factor must be attained. A Proportional-Resonant regulator is used to performance a current control with the output current of the inverter and a Multiple Second Order Generalized Integrator Frequency-Locked Loop (MSOGI-FLL) is used to detect the frequency of the low voltage 3-phase utility grid. Some low order harmonics are introduced in the low voltage 3-phase utility grid in order to see the effect of the harmonic compensator. In order to validate the model of the Photovoltaic Renewable agent, the synchronization algorithm and the inverter control algorithm, some simulations using MATLAB/SIMULINK from The MathWorks, Inc. are shown firstly, and secondly, some Real-Time Digital Simulation tests using a Real-Time Digital Simulation (RTDS) Platform are carried out
Johnson, Tony; Metcalfe, Jason; Brewster, Benjamin; Manteuffel, Christopher; Jaswa, Matthew; Tierney, Terrance
2010-04-01
The proliferation of intelligent systems in today's military demands increased focus on the optimization of human-robot interactions. Traditional studies in this domain involve large-scale field tests that require humans to operate semiautomated systems under varying conditions within military-relevant scenarios. However, provided that adequate constraints are employed, modeling and simulation can be a cost-effective alternative and supplement. The current presentation discusses a simulation effort that was executed in parallel with a field test with Soldiers operating military vehicles in an environment that represented key elements of the true operational context. In this study, "constructive" human operators were designed to represent average Soldiers executing supervisory control over an intelligent ground system. The constructive Soldiers were simulated performing the same tasks as those performed by real Soldiers during a directly analogous field test. Exercising the models in a high-fidelity virtual environment provided predictive results that represented actual performance in certain aspects, such as situational awareness, but diverged in others. These findings largely reflected the quality of modeling assumptions used to design behaviors and the quality of information available on which to articulate principles of operation. Ultimately, predictive analyses partially supported expectations, with deficiencies explicable via Soldier surveys, experimenter observations, and previously-identified knowledge gaps.
Rossetti, Manuel D
2015-01-01
Emphasizes a hands-on approach to learning statistical analysis and model building through the use of comprehensive examples, problems sets, and software applications With a unique blend of theory and applications, Simulation Modeling and Arena®, Second Edition integrates coverage of statistical analysis and model building to emphasize the importance of both topics in simulation. Featuring introductory coverage on how simulation works and why it matters, the Second Edition expands coverage on static simulation and the applications of spreadsheets to perform simulation. The new edition als
Kaloop, Mosbeh R.; Yigit, Cemal O.; Hu, Jong W.
2018-03-01
Recently, the high rate global navigation satellite system-precise point positioning (GNSS-PPP) technique has been used to detect the dynamic behavior of structures. This study aimed to increase the accuracy of the extraction oscillation properties of structural movements based on the high-rate (10 Hz) GNSS-PPP monitoring technique. A developmental model based on the combination of wavelet package transformation (WPT) de-noising and neural network prediction (NN) was proposed to improve the dynamic behavior of structures for GNSS-PPP method. A complicated numerical simulation involving highly noisy data and 13 experimental cases with different loads were utilized to confirm the efficiency of the proposed model design and the monitoring technique in detecting the dynamic behavior of structures. The results revealed that, when combined with the proposed model, GNSS-PPP method can be used to accurately detect the dynamic behavior of engineering structures as an alternative to relative GNSS method.
Energy Technology Data Exchange (ETDEWEB)
Noroy-Nadal, M H
2002-06-15
This memory presents the research concerning the characterization of materials and the Non Destructive Testing (N.D.T) by ultrasonics. The different topics include three steps: modeling, computations and experimental validation. The studied materials concern mainly metals. The memory is divided in four parts. The first one concerns the characterization of materials versus temperature. The determination of the shear modulus G(T) is especially studied for a large temperature range, and around the melting point. The second part is devoted to studies by photothermal devices essentially focused on the modeling of the mechanical displacement and the stress field in coated materials. In this particular field of interest, applications concern either the mechanical characterization of the coating, the defect detection in the structure and finally the evaluation of the coating adhesion. The third section is dedicated to microstructural characterization using acoustic microscopy. The evaluation of crystallographic texture is especially approached, for metallic objects obtained by forming. Before concluding and pointing out some perspectives to this work, the last section concerns the introduction of optimization techniques, applied to the material characterization by acoustic microscopy. (author)
Farah, J; Bonfrate, A; De Marzi, L; De Oliveira, A; Delacroix, S; Martinetti, F; Trompier, F; Clairand, I
2015-05-01
This study focuses on the configuration and validation of an analytical model predicting leakage neutron doses in proton therapy. Using Monte Carlo (MC) calculations, a facility-specific analytical model was built to reproduce out-of-field neutron doses while separately accounting for the contribution of intra-nuclear cascade, evaporation, epithermal and thermal neutrons. This model was first trained to reproduce in-water neutron absorbed doses and in-air neutron ambient dose equivalents, H*(10), calculated using MCNPX. Its capacity in predicting out-of-field doses at any position not involved in the training phase was also checked. The model was next expanded to enable a full 3D mapping of H*(10) inside the treatment room, tested in a clinically relevant configuration and finally consolidated with experimental measurements. Following the literature approach, the work first proved that it is possible to build a facility-specific analytical model that efficiently reproduces in-water neutron doses and in-air H*(10) values with a maximum difference less than 25%. In addition, the analytical model succeeded in predicting out-of-field neutron doses in the lateral and vertical direction. Testing the analytical model in clinical configurations proved the need to separate the contribution of internal and external neutrons. The impact of modulation width on stray neutrons was found to be easily adjustable while beam collimation remains a challenging issue. Finally, the model performance agreed with experimental measurements with satisfactory results considering measurement and simulation uncertainties. Analytical models represent a promising solution that substitutes for time-consuming MC calculations when assessing doses to healthy organs. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
Simulation - modeling - experiment; Simulation - modelisation - experience
Energy Technology Data Exchange (ETDEWEB)
NONE
2004-07-01
After two workshops held in 2001 on the same topics, and in order to make a status of the advances in the domain of simulation and measurements, the main goals proposed for this workshop are: the presentation of the state-of-the-art of tools, methods and experiments in the domains of interest of the Gedepeon research group, the exchange of information about the possibilities of use of computer codes and facilities, about the understanding of physical and chemical phenomena, and about development and experiment needs. This document gathers 18 presentations (slides) among the 19 given at this workshop and dealing with: the deterministic and stochastic codes in reactor physics (Rimpault G.); MURE: an evolution code coupled with MCNP (Meplan O.); neutronic calculation of future reactors at EdF (Lecarpentier D.); advance status of the MCNP/TRIO-U neutronic/thermal-hydraulics coupling (Nuttin A.); the FLICA4/TRIPOLI4 thermal-hydraulics/neutronics coupling (Aniel S.); methods of disturbances and sensitivity analysis of nuclear data in reactor physics, application to VENUS-2 experimental reactor (Bidaud A.); modeling for the reliability improvement of an ADS accelerator (Biarotte J.L.); residual gas compensation of the space charge of intense beams (Ben Ismail A.); experimental determination and numerical modeling of phase equilibrium diagrams of interest in nuclear applications (Gachon J.C.); modeling of irradiation effects (Barbu A.); elastic limit and irradiation damage in Fe-Cr alloys: simulation and experiment (Pontikis V.); experimental measurements of spallation residues, comparison with Monte-Carlo simulation codes (Fallot M.); the spallation target-reactor coupling (Rimpault G.); tools and data (Grouiller J.P.); models in high energy transport codes: status and perspective (Leray S.); other ways of investigation for spallation (Audoin L.); neutrons and light particles production at intermediate energies (20-200 MeV) with iron, lead and uranium targets (Le Colley F
Aviation Safety Simulation Model
Houser, Scott; Yackovetsky, Robert (Technical Monitor)
2001-01-01
The Aviation Safety Simulation Model is a software tool that enables users to configure a terrain, a flight path, and an aircraft and simulate the aircraft's flight along the path. The simulation monitors the aircraft's proximity to terrain obstructions, and reports when the aircraft violates accepted minimum distances from an obstruction. This model design facilitates future enhancements to address other flight safety issues, particularly air and runway traffic scenarios. This report shows the user how to build a simulation scenario and run it. It also explains the model's output.
Experimental simulations of ethylene evaporites on Titan
Czaplinski, E.; Farnsworth, K.; Singh, S.; Chevrier, V.
2017-12-01
Titan has an abundance of lakes and seas, as identified by the Cassini spacecraft. Major components of these liquid bodies include methane (CH4) and ethane (C2H6), however minor constituents are also thought to exist (e.g. ethylene (C2H4)). As the lakes and seas evaporate, 5-μm-bright deposits, resembling evaporite deposits on Earth, are left behind in a "bathtub ring" fashion. Previous studies include models of evaporites, and observations of the 5-μm-bright regions, but the community is still lacking a complete suite of experimental evaporite studies. In this study, we experimentally investigate evaporites in order to determine their composition and how they affect infrared spectra during the evaporation process. The University of Arkansas owns a specialized chamber that simulates the surface conditions of Titan ( 90 K and 1.5 bar). Gaseous hydrocarbons are condensed within the chamber and analyzed with Fourier Transform Infrared (FTIR) Spectroscopy and band depth calculations. In this study, three types of experiments were performed: ethane/ethylene, methane/ethylene, and methane/ethane/ethylene. For these experiments, methane was the only species that readily evaporated at Titan conditions (due to its high volatility), while ethane, being the more stable solvent, did not readily evaporate. Therefore, we will present spectral results of ethylene evaporite formation within these mixtures. Our results imply that evaporite formation is strongly dependent on the composition of the solvent. The north polar lakes of Titan are predicted to be methane-rich, indicating that they may be more likely to form evaporites. Alternatively, Ontario Lacus, a south polar lake, is predominately composed of ethane, which may make it more difficult to form evaporites. As we continue to study Titan's mysterious lakes and seas, we hope to draw insights on their exact composition, conditions for evaporite formation, habitability potential, and comparing Titan to prebiotic Earth.
International Nuclear Information System (INIS)
Ricciardi, G.
2008-10-01
The designing of a pressurized water reactor core subjected to seismic loading, is a major concern of the nuclear industry. We propose, in this PhD report, to establish the global behaviour equations of the core, in term of a porous medium. Local equations of fluid and structure are space averaged on a control volume, thus we define an equivalent fluid and an equivalent structure, of which unknowns are defined on the whole space. The non-linear fuel assemblies behaviour is modelled by a visco-elastic constitutive law. The fluid-structure coupling is accounted for by a body force, the expression of that force is based on empirical formula of fluid forces acting on a tube subject to an axial flow. The resulting equations are solved using a finite element method. A validation of the model, on three experimental device, is proposed. The first one presents two fuel assemblies subjected to axial flow. One of the two fuel assemblies is deviated from its position of equilibrium and released, while the other is at rest. The second one presents a six assemblies row, immersed in water, placed on a shaking table that can simulate seismic loading. Finally, the last one presents nine fuel assemblies network, arranged in a three by three, subject to an axial flow. The displacement of the central fuel assembly is imposed. The simulations are in agreement with the experiments, the model reproduces the influence of the flow of fluid on the dynamics and coupling of the fuel assemblies. (author)
National Research Council Canada - National Science Library
Gagnon, Colleen M; Stevens, William K
1999-01-01
.... Despite the high level of visibility that first generation Joint and Service-specific experimentation programs have attracted, surprisingly little attention has been paid to how to best leverage...
Comparing DINA code simulations with TCV experimental plasma equilibrium responses
International Nuclear Information System (INIS)
Khayrutdinov, R.R.; Lister, J.B.; Lukash, V.E.; Wainwright, J.P.
2000-08-01
The DINA non-linear time dependent simulation code has been validated against an extensive set of plasma equilibrium response experiments carried out on the TCV tokamak. Limited and diverted plasmas are found to be well modelled during the plasma current flat top. In some simulations the application of the PF coil voltage stimulation pulse sufficiently changed the plasma equilibrium that the vertical position feedback control loop became unstable. This behaviour was also found in the experimental work, and cannot be reproduced using linear time-independent models. A single null diverted plasma discharge was also simulated from start-up to shut-down and the results were found to accurately reproduce their experimental equivalents. The most significant difference noted was the penetration time of the poloidal flux, leading to a delayed onset of sawtoothing in the DINA simulation. The complete set of frequency stimulation experiments used to measure the open loop tokamak plasma equilibrium response was also simulated using DINA and the results were analysed in an identical fashion to the experimental data. The frequency response of the DINA simulations agrees with the experimental results. Comparisons with linear models are also discussed to identify areas of good and only occasionally less good agreement. (author)
Energy Technology Data Exchange (ETDEWEB)
Adkins, Harold E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
2013-04-01
Under current U.S. Nuclear Regulatory Commission regulation, it is not sufficient for used nuclear fuel (UNF) to simply maintain its integrity during the storage period, it must maintain its integrity in such a way that it can withstand the physical forces of handling and transportation associated with restaging the fuel and moving it to treatment or recycling facilities, or a geologic repository. Hence it is necessary to understand the performance characteristics of aged UNF cladding and ancillary components under loadings stemming from transport initiatives. Researchers would like to demonstrate that enough information, including experimental support and modeling and simulation capabilities, exists to establish a preliminary determination of UNF structural performance under normal conditions of transport (NCT). This research, development and demonstration (RD&D) plan describes a methodology, including development and use of analytical models, to evaluate loading and associated mechanical responses of UNF rods and key structural components. This methodology will be used to provide a preliminary assessment of the performance characteristics of UNF cladding and ancillary components under rail-related NCT loading. The methodology couples modeling and simulation and experimental efforts currently under way within the Used Fuel Disposition Campaign (UFDC). The methodology will involve limited uncertainty quantification in the form of sensitivity evaluations focused around available fuel and ancillary fuel structure properties exclusively. The work includes collecting information via literature review, soliciting input/guidance from subject matter experts, performing computational analyses, planning experimental measurement and possible execution (depending on timing), and preparing a variety of supporting documents that will feed into and provide the basis for future initiatives. The methodology demonstration will focus on structural performance evaluation of
2014-07-01
The formulation of constitutive equations for asphaltic pavement is based on rheological models which include the asphalt mixture, additives, and the bitumen. In terms of the asphalt, the rheology addresses the flow and permanent deformation in time,...
Directory of Open Access Journals (Sweden)
Guillermo Rey
2016-11-01
Full Text Available Tri-generation plants will have an important role in the near future in the residential sector where heating and cooling demands come into play throughout the year. Depending on the building’s location, the characteristics of its enclosure and its use, the thermal loads and demands will be different. This article analyses and compares a combined cooling, heating and power (CCHP system tested in the laboratory and a single household located in Spain. The cooling capacity is obtained using a reversible heat pump where the compressor is driven directly by a gas engine with internal combustion engine (ICE technology. The tests were carried out in a work bench at three different operating speeds. A variable-speed model is developed in the TRNSYS simulation environment with an operating strategy following the thermal load (FTL. Once the micro-CCHP system was modeled with experimental data and validated, it was dynamically simulated to analyze its performance in different climatic zones defined in the Spanish “Código Técnico de la Edificación” (CTE. This study reveals that the micro-CCHP system is suitable in mild weathers during the summer season.
International Nuclear Information System (INIS)
Sundelll-Bergman, S.; Avila, R.; Cruz, I. de la; Xu, S.; Puhakainen, M.; Heikkinene, T.; Rahola, T.; Hosseini, A.; Nielsen, Sven; Sigurgeirsson, M.
2009-06-01
This report summarises the findings of a project on assessing the impact of releases of radionuclides into sewage systems and was established to provide more knowledge and suitable tools for emergency preparedness purposes in urban areas. It was known that the design of sewage plants, and their wastewater treatments, is rather similar between the Nordic countries. One sewage plant in each of the five Nordic countries was selected for assessing the impact of radionuclide releases from hospitals into their sewerage systems. Measurements and model predictions of dose assessments to different potentially exposed members of the public were carried out. The results from the dose assessments indicate that in case of routine releases annual doses to the three hypothetical groups of individuals are most likely insignificant. Estimated doses for workers are below 10 μSv/y, for the two studied radionuclides 99mTc and 131I. If uncertainties in the predictions of activity concentrations in sludge are considered, then the probability of obtaining doses above 10 μSv/y may not be insignificant. The models and approaches developed can also be applied in case of accidental releases. A laboratory inter-comparison exercise was also organised to compare analytical results across the laboratories participating in the project, using both 131I, dominating man-made radionuclide in sewage systems due to the medical use. A process oriented model of the biological treatment is also proposed in the report that does not require as much input data as for the LUCIA model. This model is a combination of a simplified well known Activated Sludge Model No.1 (Henze, 1987) and the Kd concept used in the LUCIA model. The simplified model is able to estimate the concentrations and the retention time of the sludge in different parts of the treatment plant, which in turn, can be used as a tool for the dose assessment purpose.filled by the activity. (au)
Energy Technology Data Exchange (ETDEWEB)
Sundelll-Bergman, S. (Vattenfall Power Consultant, Stockholm (Sweden)); Avila, R.; Cruz, I. de la (Facilia AB, (Sweden)); Xu, S. (Swedish Radiation Safety Authority, (Sweden)); Puhakainen, M.; Heikkinene, T.; Rahola, T. (STUK (Finland)); Hosseini, A. (Norwegian Radiation Protection Authority (Norway)); Nielsen, Sven (Risoe National Laboratory for Sustainable Energy, DTU (Denmark)); Sigurgeirsson, M. (Geislavarnir rikisins (Iceland))
2009-06-15
This report summarises the findings of a project on assessing the impact of releases of radionuclides into sewage systems and was established to provide more knowledge and suitable tools for emergency preparedness purposes in urban areas. It was known that the design of sewage plants, and their wastewater treatments, is rather similar between the Nordic countries. One sewage plant in each of the five Nordic countries was selected for assessing the impact of radionuclide releases from hospitals into their sewerage systems. Measurements and model predictions of dose assessments to different potentially exposed members of the public were carried out. The results from the dose assessments indicate that in case of routine releases annual doses to the three hypothetical groups of individuals are most likely insignificant. Estimated doses for workers are below 10 muSv/y, for the two studied radionuclides 99mTc and 131I. If uncertainties in the predictions of activity concentrations in sludge are considered, then the probability of obtaining doses above 10 muSv/y may not be insignificant. The models and approaches developed can also be applied in case of accidental releases. A laboratory inter-comparison exercise was also organised to compare analytical results across the laboratories participating in the project, using both 131I, dominating man-made radionuclide in sewage systems due to the medical use. A process oriented model of the biological treatment is also proposed in the report that does not require as much input data as for the LUCIA model. This model is a combination of a simplified well known Activated Sludge Model No.1 (Henze, 1987) and the Kd concept used in the LUCIA model. The simplified model is able to estimate the concentrations and the retention time of the sludge in different parts of the treatment plant, which in turn, can be used as a tool for the dose assessment purpose.filled by the activity. (au)
DEFF Research Database (Denmark)
Dumont, Olivier; Carmo, Carolina; Quoilin, Sylvain
2015-01-01
This paper presents an innovative building comprising a heat pump connected to a solar roof and a geothermal heat exchanger. This unit is able to invert its cycle and operate as an Organic Rankine Cycle (ORC). The solar roof is producing large amount of heat throughout the year. This allows...... and fluid R134a shows promising performance with a net electrical energy produced over one year reaching 4030 kWh. Following that, a prototype has been built and has proven the feasibility of the technology. Finally, a simulation code including the building, the ground heat exchanger, the thermal energy...... storage, the solar roof and the reversible HP/ORC unit is developed and allows to perform a sensivity analysis. Annual results show that this technology leads to a Positive Energy Building....
Simulation in Complex Modelling
DEFF Research Database (Denmark)
Nicholas, Paul; Ramsgaard Thomsen, Mette; Tamke, Martin
2017-01-01
This paper will discuss the role of simulation in extended architectural design modelling. As a framing paper, the aim is to present and discuss the role of integrated design simulation and feedback between design and simulation in a series of projects under the Complex Modelling framework. Complex...... performance, engage with high degrees of interdependency and allow the emergence of design agency and feedback between the multiple scales of architectural construction. This paper presents examples for integrated design simulation from a series of projects including Lace Wall, A Bridge Too Far and Inflated...... Restraint developed for the research exhibition Complex Modelling, Meldahls Smedie Gallery, Copenhagen in 2016. Where the direct project aims and outcomes have been reported elsewhere, the aim for this paper is to discuss overarching strategies for working with design integrated simulation....
Waterlander, Wilma E; Blakely, Tony; Nghiem, Nhung; Cleghorn, Christine L; Eyles, Helen; Genc, Murat; Wilson, Nick; Jiang, Yannan; Swinburn, Boyd; Jacobi, Liana; Michie, Jo; Ni Mhurchu, Cliona
2016-07-19
There is a need for accurate and precise food price elasticities (PE, change in consumer demand in response to change in price) to better inform policy on health-related food taxes and subsidies. The Price Experiment and Modelling (Price ExaM) study aims to: I) derive accurate and precise food PE values; II) quantify the impact of price changes on quantity and quality of discrete food group purchases and; III) model the potential health and disease impacts of a range of food taxes and subsidies. To achieve this, we will use a novel method that includes a randomised Virtual Supermarket experiment and econometric methods. Findings will be applied in simulation models to estimate population health impact (quality-adjusted life-years [QALYs]) using a multi-state life-table model. The study will consist of four sequential steps: 1. We generate 5000 price sets with random price variation for all 1412 Virtual Supermarket food and beverage products. Then we add systematic price variation for foods to simulate five taxes and subsidies: a fruit and vegetable subsidy and taxes on sugar, saturated fat, salt, and sugar-sweetened beverages. 2. Using an experimental design, 1000 adult New Zealand shoppers complete five household grocery shops in the Virtual Supermarket where they are randomly assigned to one of the 5000 price sets each time. 3. Output data (i.e., multiple observations of price configurations and purchased amounts) are used as inputs to econometric models (using Bayesian methods) to estimate accurate PE values. 4. A disease simulation model will be run with the new PE values as inputs to estimate QALYs gained and health costs saved for the five policy interventions. The Price ExaM study has the potential to enhance public health and economic disciplines by introducing internationally novel scientific methods to estimate accurate and precise food PE values. These values will be used to model the potential health and disease impacts of various food pricing policy
Directory of Open Access Journals (Sweden)
Wilma E. Waterlander
2016-07-01
Full Text Available Abstract Background There is a need for accurate and precise food price elasticities (PE, change in consumer demand in response to change in price to better inform policy on health-related food taxes and subsidies. Methods/Design The Price Experiment and Modelling (Price ExaM study aims to: I derive accurate and precise food PE values; II quantify the impact of price changes on quantity and quality of discrete food group purchases and; III model the potential health and disease impacts of a range of food taxes and subsidies. To achieve this, we will use a novel method that includes a randomised Virtual Supermarket experiment and econometric methods. Findings will be applied in simulation models to estimate population health impact (quality-adjusted life-years [QALYs] using a multi-state life-table model. The study will consist of four sequential steps: 1. We generate 5000 price sets with random price variation for all 1412 Virtual Supermarket food and beverage products. Then we add systematic price variation for foods to simulate five taxes and subsidies: a fruit and vegetable subsidy and taxes on sugar, saturated fat, salt, and sugar-sweetened beverages. 2. Using an experimental design, 1000 adult New Zealand shoppers complete five household grocery shops in the Virtual Supermarket where they are randomly assigned to one of the 5000 price sets each time. 3. Output data (i.e., multiple observations of price configurations and purchased amounts are used as inputs to econometric models (using Bayesian methods to estimate accurate PE values. 4. A disease simulation model will be run with the new PE values as inputs to estimate QALYs gained and health costs saved for the five policy interventions. Discussion The Price ExaM study has the potential to enhance public health and economic disciplines by introducing internationally novel scientific methods to estimate accurate and precise food PE values. These values will be used to model the potential
Scientific Modeling and simulations
Diaz de la Rubia, Tomás
2009-01-01
Showcases the conceptual advantages of modeling which, coupled with the unprecedented computing power through simulations, allow scientists to tackle the formibable problems of our society, such as the search for hydrocarbons, understanding the structure of a virus, or the intersection between simulations and real data in extreme environments
Automated Simulation Model Generation
Huang, Y.
2013-01-01
One of today's challenges in the field of modeling and simulation is to model increasingly larger and more complex systems. Complex models take long to develop and incur high costs. With the advances in data collection technologies and more popular use of computer-aided systems, more data has become
Experimental and numerical simulation of carbon manganese steel ...
African Journals Online (AJOL)
Experimental and numerical simulation of carbon manganese steel for cyclic plastic behaviour. J Shit, S Dhar, S Acharyya. Abstract. The paper deals with finite element modeling of saturated low cycle fatigue and the cyclic hardening phenomena of the materials Sa333 grade 6 carbon steel and SS316 stainless steel.
Kamath, Ashwin; Urval, Rathnakar P; Shenoy, Ashok K
2017-01-01
A randomized controlled pilot study was carried out to determine the effect of a 15-minute practice of ANB exercise on experimentally induced anxiety using the simulated public speaking model in yoga-naïve healthy young adults. Thirty consenting medical students were equally divided into test and control groups. The test group performed alternate nostril breathing exercise for 15 minutes, while the control group sat in a quiet room before participating in the simulated public speaking test (SPST). Visual Analog Mood Scale and Self-Statements during Public Speaking scale were used to measure the mood state at different phases of the SPST. The psychometric scores of both groups were comparable at baseline. Repeated-measures ANOVA showed a significant effect of phase ( p < 0.05), but group and gender did not have statistically significant influence on the mean anxiety scores. However, the test group showed a trend towards lower mean scores for the anxiety factor when compared with the control group. Considering the limitations of this pilot study and the trend seen towards lower anxiety in the test group, alternate nostril breathing may have potential anxiolytic effect in acute stressful situations. A study with larger sample size is therefore warranted. This trial is registered with CTRI/2014/03/004460.
AEGIS geologic simulation model
International Nuclear Information System (INIS)
Foley, M.G.
1982-01-01
The Geologic Simulation Model (GSM) is used by the AEGIS (Assessment of Effectiveness of Geologic Isolation Systems) program at the Pacific Northwest Laboratory to simulate the dynamic geology and hydrology of a geologic nuclear waste repository site over a million-year period following repository closure. The GSM helps to organize geologic/hydrologic data; to focus attention on active natural processes by requiring their simulation; and, through interactive simulation and calibration, to reduce subjective evaluations of the geologic system. During each computer run, the GSM produces a million-year geologic history that is possible for the region and the repository site. In addition, the GSM records in permanent history files everything that occurred during that time span. Statistical analyses of data in the history files of several hundred simulations are used to classify typical evolutionary paths, to establish the probabilities associated with deviations from the typical paths, and to determine which types of perturbations of the geologic/hydrologic system, if any, are most likely to occur. These simulations will be evaluated by geologists familiar with the repository region to determine validity of the results. Perturbed systems that are determined to be the most realistic, within whatever probability limits are established, will be used for the analyses that involve radionuclide transport and dose models. The GSM is designed to be continuously refined and updated. Simulation models are site specific, and, although the submodels may have limited general applicability, the input data equirements necessitate detailed characterization of each site before application
Experimental Object-Oriented Modelling
DEFF Research Database (Denmark)
Hansen, Klaus Marius
through, e.g., technical prototyping and active user involvement. We introduce and examine “experimental object-oriented modelling” as the intersection of these practices. The contributions of this thesis are expected to be within three perspectives on models and modelling in experimental system...... development: Grounding We develop an empirically based conceptualization of modelling and use of models in system development projects characterized by a high degree of uncertainty in requirements and point to implications for tools and techniques for modelling in such a setting. Techniques We introduce......This thesis examines object-oriented modelling in experimental system development. Object-oriented modelling aims at representing concepts and phenomena of a problem domain in terms of classes and objects. Experimental system development seeks active experimentation in a system development project...
Validation of simulation models
DEFF Research Database (Denmark)
Rehman, Muniza; Pedersen, Stig Andur
2012-01-01
In philosophy of science, the interest for computational models and simulations has increased heavily during the past decades. Different positions regarding the validity of models have emerged but the views have not succeeded in capturing the diversity of validation methods. The wide variety...
Simulation prototyping of an experimental solar house
Energy Technology Data Exchange (ETDEWEB)
Osborne, A.; Baur, S. [Department of Civil, Architectural and Environmental Engineering, Missouri University of Science and Technology, 1401 Pine Street, Rolla, MO 65409 (United States); Grantham, K. [Department of Engineering Management, Missouri University of Science and Technology, 600 W. 14th Street, Rolla, MO 65409 (United States)
2010-06-15
This paper presents a comparative analysis between an energy simulation model and an actual solar home. The case study used was the Team Missouri's 2009 Solar Decathlon entry. The home was evaluated using the predicted data developed with the use of Energy-10 Version 1.8. The software simulates the energy use performance of building strategies ranging from building envelope and system efficiency options. The performance data used was collected during the 2009 Solar Decathlon competition. Results comparing energy efficient strategies, consumption and generation are explored with future implications discussed. (authors)
Validation process of simulation model
International Nuclear Information System (INIS)
San Isidro, M. J.
1998-01-01
It is presented a methodology on empirical validation about any detailed simulation model. This king of validation it is always related with an experimental case. The empirical validation has a residual sense, because the conclusions are based on comparisons between simulated outputs and experimental measurements. This methodology will guide us to detect the fails of the simulation model. Furthermore, it can be used a guide in the design of posterior experiments. Three steps can be well differentiated: Sensitivity analysis. It can be made with a DSA, differential sensitivity analysis, and with a MCSA, Monte-Carlo sensitivity analysis. Looking the optimal domains of the input parameters. It has been developed a procedure based on the Monte-Carlo methods and Cluster techniques, to find the optimal domains of these parameters. Residual analysis. This analysis has been made on the time domain and on the frequency domain, it has been used the correlation analysis and spectral analysis. As application of this methodology, it is presented the validation carried out on a thermal simulation model on buildings, Esp., studying the behavior of building components on a Test Cell of LECE of CIEMAT. (Author) 17 refs
ANOVA parameters influence in LCF experimental data and simulation results
Directory of Open Access Journals (Sweden)
Vercelli A.
2010-06-01
Full Text Available The virtual design of components undergoing thermo mechanical fatigue (TMF and plastic strains is usually run in many phases. The numerical finite element method gives a useful instrument which becomes increasingly effective as the geometrical and numerical modelling gets more accurate. The constitutive model definition plays an important role in the effectiveness of the numerical simulation [1, 2] as, for example, shown in Figure 1. In this picture it is shown how a good cyclic plasticity constitutive model can simulate a cyclic load experiment. The component life estimation is the subsequent phase and it needs complex damage and life estimation models [3-5] which take into account of several parameters and phenomena contributing to damage and life duration. The calibration of these constitutive and damage models requires an accurate testing activity. In the present paper the main topic of the research activity is to investigate whether the parameters, which result to be influent in the experimental activity, influence the numerical simulations, thus defining the effectiveness of the models in taking into account of all the phenomena actually influencing the life of the component. To obtain this aim a procedure to tune the parameters needed to estimate the life of mechanical components undergoing TMF and plastic strains is presented for commercial steel. This procedure aims to be easy and to allow calibrating both material constitutive model (for the numerical structural simulation and the damage and life model (for life assessment. The procedure has been applied to specimens. The experimental activity has been developed on three sets of tests run at several temperatures: static tests, high cycle fatigue (HCF tests, low cycle fatigue (LCF tests. The numerical structural FEM simulations have been run on a commercial non linear solver, ABAQUS®6.8. The simulations replied the experimental tests. The stress, strain, thermal results from the thermo
NUMERICAL SIMULATION AND MODELING OF UNSTEADY FLOW ...
African Journals Online (AJOL)
2014-06-30
Jun 30, 2014 ... objective of this study is to control the simulation of unsteady flows around structures. ... Aerospace, our results were in good agreement with experimental .... Two-Equation Eddy-Viscosity Turbulence Models for Engineering.
International Nuclear Information System (INIS)
Lee, M.J.; Sheppard, J.C.; Sullenberger, M.; Woodley, M.D.
1983-09-01
On-line mathematical models have been used successfully for computer controlled operation of SPEAR and PEP. The same model control concept is being implemented for the operation of the LINAC and for the Damping Ring, which will be part of the Stanford Linear Collider (SLC). The purpose of this paper is to describe the general relationships between models, simulations and the control system for any machine at SLAC. The work we have done on the development of the empirical model for the Damping Ring will be presented as an example
PSH Transient Simulation Modeling
Energy Technology Data Exchange (ETDEWEB)
Muljadi, Eduard [National Renewable Energy Laboratory (NREL), Golden, CO (United States)
2017-12-21
PSH Transient Simulation Modeling presentation from the WPTO FY14 - FY16 Peer Review. Transient effects are an important consideration when designing a PSH system, yet numerical techniques for hydraulic transient analysis still need improvements for adjustable-speed (AS) reversible pump-turbine applications.
Modeling and Simulation of Nanoindentation
Huang, Sixie; Zhou, Caizhi
2017-11-01
Nanoindentation is a hardness test method applied to small volumes of material which can provide some unique effects and spark many related research activities. To fully understand the phenomena observed during nanoindentation tests, modeling and simulation methods have been developed to predict the mechanical response of materials during nanoindentation. However, challenges remain with those computational approaches, because of their length scale, predictive capability, and accuracy. This article reviews recent progress and challenges for modeling and simulation of nanoindentation, including an overview of molecular dynamics, the quasicontinuum method, discrete dislocation dynamics, and the crystal plasticity finite element method, and discusses how to integrate multiscale modeling approaches seamlessly with experimental studies to understand the length-scale effects and microstructure evolution during nanoindentation tests, creating a unique opportunity to establish new calibration procedures for the nanoindentation technique.
DEFF Research Database (Denmark)
Larsen, Gunner Chr.; Madsen Aagaard, Helge; Larsen, Torben J.
We present a consistent, physically based theory for the wake meandering phenomenon, which we consider of crucial importance for the overall description of wind turbine loadings in wind farms. In its present version the model is confined to single wake situations. The model philosophy does, howev...... methodology has been implemented in the aeroelastic code HAWC2, and example simulations of wake situations, from the small Tjæreborg wind farm, have been performed showing satisfactory agreement between predictions and measurements...
Structured building model reduction toward parallel simulation
Energy Technology Data Exchange (ETDEWEB)
Dobbs, Justin R. [Cornell University; Hencey, Brondon M. [Cornell University
2013-08-26
Building energy model reduction exchanges accuracy for improved simulation speed by reducing the number of dynamical equations. Parallel computing aims to improve simulation times without loss of accuracy but is poorly utilized by contemporary simulators and is inherently limited by inter-processor communication. This paper bridges these disparate techniques to implement efficient parallel building thermal simulation. We begin with a survey of three structured reduction approaches that compares their performance to a leading unstructured method. We then use structured model reduction to find thermal clusters in the building energy model and allocate processing resources. Experimental results demonstrate faster simulation and low error without any interprocessor communication.
Liquid metal cooled experimental fast reactor simulator
International Nuclear Information System (INIS)
Guimaraes, Lamartine; Braz Filho, Francisco; Borges, Eduardo M.; Rosa, Mauricio A.P.; Rocamora, Francisco; Hirdes, Viviane R.
1997-01-01
This paper is a continuation of the work that has been done in the area of fast reactor component dynamic analysis, as part of the REARA project at the IEAv/CTA-Brazil. A couple of preceding papers, presented in other meetings, introduced major concept design components of the REARA reactor. The components are set together in order to represent a full model of the power plant. Full model transient results will be presented, together with several parameters to help us to better establish the REARA experimental plant concept. (author). 8 refs., 6 figs., 3 tabs
Experimental simulation of closed timelike curves.
Ringbauer, Martin; Broome, Matthew A; Myers, Casey R; White, Andrew G; Ralph, Timothy C
2014-06-19
Closed timelike curves are among the most controversial features of modern physics. As legitimate solutions to Einstein's field equations, they allow for time travel, which instinctively seems paradoxical. However, in the quantum regime these paradoxes can be resolved, leaving closed timelike curves consistent with relativity. The study of these systems therefore provides valuable insight into nonlinearities and the emergence of causal structures in quantum mechanics--essential for any formulation of a quantum theory of gravity. Here we experimentally simulate the nonlinear behaviour of a qubit interacting unitarily with an older version of itself, addressing some of the fascinating effects that arise in systems traversing a closed timelike curve. These include perfect discrimination of non-orthogonal states and, most intriguingly, the ability to distinguish nominally equivalent ways of preparing pure quantum states. Finally, we examine the dependence of these effects on the initial qubit state, the form of the unitary interaction and the influence of decoherence.
Steel Fibers Reinforced Concrete Pipes - Experimental Tests and Numerical Simulation
Doru, Zdrenghea
2017-10-01
The paper presents in the first part a state of the art review of reinforced concrete pipes used in micro tunnelling realised through pipes jacking method and design methods for steel fibres reinforced concrete. In part two experimental tests are presented on inner pipes with diameters of 1410mm and 2200mm, and specimens (100x100x500mm) of reinforced concrete with metal fibres (35 kg / m3). In part two experimental tests are presented on pipes with inner diameters of 1410mm and 2200mm, and specimens (100x100x500mm) of reinforced concrete with steel fibres (35 kg / m3). The results obtained are analysed and are calculated residual flexural tensile strengths which characterise the post-cracking behaviour of steel fibres reinforced concrete. In the third part are presented numerical simulations of the tests of pipes and specimens. The model adopted for the pipes test was a three-dimensional model and loads considered were those obtained in experimental tests at reaching breaking forces. Tensile stresses determined were compared with mean flexural tensile strength. To validate tensile parameters of steel fibres reinforced concrete, experimental tests of the specimens were modelled with MIDAS program to reproduce the flexural breaking behaviour. To simulate post - cracking behaviour was used the method σ — ε based on the relationship stress - strain, according to RILEM TC 162-TDF. For the specimens tested were plotted F — δ diagrams, which have been superimposed for comparison with the similar diagrams of experimental tests. The comparison of experimental results with those obtained from numerical simulation leads to the following conclusions: - the maximum forces obtained by numerical calculation have higher values than the experimental values for the same tensile stresses; - forces corresponding of residual strengths have very similar values between the experimental and numerical calculations; - generally the numerical model estimates a breaking force greater
Directory of Open Access Journals (Sweden)
José Hélio Zen Junior
2012-01-01
Full Text Available PURPOSE: To develop experimental models to evaluate the effects of hydrochloric acid associated with the pepsin instilled in the mucosa of the upper esophagus and the esophagogastric junction of young male rats Wistar, simulating injury caused by gastroesophageal reflux on the mucosa of aero-digestive tract in humans as well as the action of the risk exposure of mucosa to cigarette smoke. METHODS: Fifty young male Wistar rats divided in 5 groups with 10 animals each one, respectively simulating pharyngo-laryngeal reflux and gastroesophageal reflux, pharyngo-laryngeal reflux and smoking, smoking only, gastroesophageal reflux and control group. RESULTS: The histopathologic studies no recorded neoplasias, only mild changes and no significant alterations. The hemo-oximetry (carboxyhemoglobin and methemoglobim and CO2 concentration confirm that the animals were submitted to high intensity of exposure to carcinogens in tobacco and its derivatives. CONCLUSION: The experimental models were highly efficient, practical, easy to use and economical and can be employed in other similar studies to determine the harmful effects by smoking and reflux.OBJETIVO: Desenvolver modelos experimentais para avaliar os efeitos do ácido clorídrico associado a pepsina, instilados na mucosa da parte superior do esôfago e da junção esofagogástrica de jovens ratos Wistar, simulando lesão causada por refluxo gastroesofágico na mucosa do trato aero-digestivo em humanos, bem como a ação da exposição ao risco de mucosa, como a fumaça de cigarro. MÉTODOS: Cinqüenta jovens ratos Wistar divididos em cinco grupos com 10 animais cada um, respectivamente, simulando o refluxo faringo-laríngeo e refluxo gastroesofágico, refluxo faringo-laríngeo e tabagismo, tabagismo só, refluxo gastroesofágico e grupo controle. RESULTADOS: os estudos histopatológicos não registraram neoplasias, apenas leves alterações e não significativas. O hemo-oximetria (carboxiemoglobina e
Directory of Open Access Journals (Sweden)
P. Trambauer
2011-09-01
Full Text Available The groundwater flow models currently used in the western part of The Netherlands and in other similar peaty areas are thought to be a too simplified representation of the hydrological reality. One of the reasons is that, due to the schematization of the subsoil, its heterogeneity cannot be represented adequately. Moreover, the applicability of Darcy's law in these types of soils has been questioned, but this law forms the basis of most groundwater flow models.
With the purpose of assessing the typical heterogeneity of the subsoil and to verify the applicability of Darcy's law, geo-hydrological fieldwork was completed at an experimental field within a research area in the western part of The Netherlands. The assessments were carried out for the so-called Complex Confining Layer (CCL, which is the Holocene peaty to clayey layer overlying Pleistocene sandy deposits. Borehole drilling through the CCL with a hand auger was completed and revealed the typical heterogeneous character of this layer, showing a dominance of muddy, humified peat which is alternated with fresher peat and clay.
Slug tests were carried out to study the applicability of Darcy's law, given that previous studies suggested its non-validity for humified peat soils due to a variable horizontal hydraulic conductivity K_{h} with head differences. For higher humification degrees, the experiments indeed suggested a variable K_{h}, but this appeared to be the result of the inappropriate use of steady-state formulae for transient experiments in peaty environments. The muddy peat sampled has a rather plastic nature, and the high compressibility of this material leads to transient behavior. However, using transient formulae, the slug tests conducted for different initial groundwater heads showed that there was hardly any evidence of a variation of the hydraulic conductivity with the applied head differences. Therefore, Darcy's law can be used
Thermomechanical simulations and experimental validation for high speed incremental forming
Ambrogio, Giuseppina; Gagliardi, Francesco; Filice, Luigino; Romero, Natalia
2016-10-01
Incremental sheet forming (ISF) consists in deforming only a small region of the workspace through a punch driven by a NC machine. The drawback of this process is its slowness. In this study, a high speed variant has been investigated from both numerical and experimental points of view. The aim has been the design of a FEM model able to perform the material behavior during the high speed process by defining a thermomechanical model. An experimental campaign has been performed by a CNC lathe with high speed to test process feasibility. The first results have shown how the material presents the same performance than in conventional speed ISF and, in some cases, better material behavior due to the temperature increment. An accurate numerical simulation has been performed to investigate the material behavior during the high speed process confirming substantially experimental evidence.
Experimentation and numerical simulation of steel fibre reinforced concrete pipes
International Nuclear Information System (INIS)
Fuente, A. de la; Domingues de Figueiredo, A.; Aguado, A.; Molins, C.; Chama Neto, P. J.
2011-01-01
The results concerning on an experimental and a numerical study related to SFRCP are presented. Eighteen pipes with an internal diameter of 600 mm and fibre dosages of 10, 20 and 40 kg/m3 were manufactured and tested. Some technological aspects were concluded. Likewise, a numerical parameterized model was implemented. With this model, the simulation of the resistant behaviour of SFRCP can be performed. In this sense, the results experimentally obtained were contrasted with those suggested by means MAP reaching very satisfactory correlations. Taking it into account, it could be said that the numerical model is a useful tool for the optimal design of the SFRCP fibre dosages, avoiding the need of the systematic employment of the test as an indirect design method. Consequently, the use of this model would reduce the overall cost of the pipes and would give fibres a boost as a solution for this structural typology. (Author) 27 refs.
Simulation modeling and analysis with Arena
Altiok, Tayfur
2007-01-01
Simulation Modeling and Analysis with Arena is a highly readable textbook which treats the essentials of the Monte Carlo discrete-event simulation methodology, and does so in the context of a popular Arena simulation environment. It treats simulation modeling as an in-vitro laboratory that facilitates the understanding of complex systems and experimentation with what-if scenarios in order to estimate their performance metrics. The book contains chapters on the simulation modeling methodology and the underpinnings of discrete-event systems, as well as the relevant underlying probability, statistics, stochastic processes, input analysis, model validation and output analysis. All simulation-related concepts are illustrated in numerous Arena examples, encompassing production lines, manufacturing and inventory systems, transportation systems, and computer information systems in networked settings.· Introduces the concept of discrete event Monte Carlo simulation, the most commonly used methodology for modeli...
Tong, Xuming; Chen, Jinghang; Miao, Hongyu; Li, Tingting; Zhang, Le
2015-01-01
Agent-based models (ABM) and differential equations (DE) are two commonly used methods for immune system simulation. However, it is difficult for ABM to estimate key parameters of the model by incorporating experimental data, whereas the differential equation model is incapable of describing the complicated immune system in detail. To overcome these problems, we developed an integrated ABM regression model (IABMR). It can combine the advantages of ABM and DE by employing ABM to mimic the multi-scale immune system with various phenotypes and types of cells as well as using the input and output of ABM to build up the Loess regression for key parameter estimation. Next, we employed the greedy algorithm to estimate the key parameters of the ABM with respect to the same experimental data set and used ABM to describe a 3D immune system similar to previous studies that employed the DE model. These results indicate that IABMR not only has the potential to simulate the immune system at various scales, phenotypes and cell types, but can also accurately infer the key parameters like DE model. Therefore, this study innovatively developed a complex system development mechanism that could simulate the complicated immune system in detail like ABM and validate the reliability and efficiency of model like DE by fitting the experimental data. PMID:26535589
Numerical simulation and experimental validation of coiled adiabatic capillary tubes
Energy Technology Data Exchange (ETDEWEB)
Garcia-Valladares, O. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico (UNAM), Apdo. Postal 34, 62580 Temixco, Morelos (Mexico)
2007-04-15
The objective of this study is to extend and validate the model developed and presented in previous works [O. Garcia-Valladares, C.D. Perez-Segarra, A. Oliva, Numerical simulation of capillary tube expansion devices behaviour with pure and mixed refrigerants considering metastable region. Part I: mathematical formulation and numerical model, Applied Thermal Engineering 22 (2) (2002) 173-182; O. Garcia-Valladares, C.D. Perez-Segarra, A. Oliva, Numerical simulation of capillary tube expansion devices behaviour with pure and mixed refrigerants considering metastable region. Part II: experimental validation and parametric studies, Applied Thermal Engineering 22 (4) (2002) 379-391] to coiled adiabatic capillary tube expansion devices working with pure and mixed refrigerants. The discretized governing equations are coupled using an implicit step by step method. A special treatment has been implemented in order to consider transitions (subcooled liquid region, metastable liquid region, metastable two-phase region and equilibrium two-phase region). All the flow variables (enthalpies, temperatures, pressures, vapor qualities, velocities, heat fluxes, etc.) together with the thermophysical properties are evaluated at each point of the grid in which the domain is discretized. The numerical model allows analysis of aspects such as geometry, type of fluid (pure substances and mixtures), critical or non-critical flow conditions, metastable regions, and transient aspects. Comparison of the numerical simulation with a wide range of experimental data presented in the technical literature will be shown in the present article in order to validate the model developed. (author)
Energy Technology Data Exchange (ETDEWEB)
Larsen, G.C.; Aagaard Madsen, H.; Larsen, T.J.; Troldborg, N.
2008-07-15
We present a consistent, physically based theory for the wake meandering phenomenon, which we consider of crucial importance for the overall description of wind turbine loadings in wind farms. In its present version the model is confined to single wake situations. The model philosophy does, however, have the potential to include also mutual wake interaction phenomenons. The basic conjecture behind the dynamic wake meandering (DWM) model is that wake transportation in the atmospheric boundary layer is driven by the large scale lateral- and vertical turbulence components. Based on this conjecture a stochastic model of the downstream wake meandering is formulated. In addition to the kinematic formulation of the dynamics of the 'meandering frame of reference', models characterizing the mean wake deficit as well as the added wake turbulence, described in the meandering frame of reference, are an integrated part the DWM model complex. For design applications, the computational efficiency of wake deficit prediction is a key issue. A computationally low cost model is developed for this purpose. Likewise, the character of the added wake turbulence, generated by the up-stream turbine in the form of shed and trailed vorticity, has been approached by a simple semi-empirical model essentially based on an eddy viscosity philosophy. Contrary to previous attempts to model wake loading, the DWM approach opens for a unifying description in the sense that turbine power- and load aspects can be treated simultaneously. This capability is a direct and attractive consequence of the model being based on the underlying physical process, and it potentially opens for optimization of wind farm topology, of wind farm operation as well as of control strategies for the individual turbine. To establish an integrated modeling tool, the DWM methodology has been implemented in the aeroelastic code HAWC2, and example simulations of wake situations, from the small Tjaereborg wind farm, have
Computer simulations of the random barrier model
DEFF Research Database (Denmark)
Schrøder, Thomas; Dyre, Jeppe
2002-01-01
A brief review of experimental facts regarding ac electronic and ionic conduction in disordered solids is given followed by a discussion of what is perhaps the simplest realistic model, the random barrier model (symmetric hopping model). Results from large scale computer simulations are presented...
Energy Technology Data Exchange (ETDEWEB)
Loehn, Helmut
2010-11-03
danger of washing out of the phosphoric acid. In an additional test row the Celtec-P-1000 HT-MEA was subjected to temperature change cycles (40 - 160 C), which lead to irreversible voltage losses. In a final test row performance tests were carried out with a HT-PEM fuel cell stack (16 cells /1 kW), developed in the fuel cell research centre of Volkswagen with a special gas diffusion electrode, which should avoid the degradation at deep temperatures. In these examinations no irreversible voltage losses could be detected, but the tests had to be aborted because of leakage problems. The by the experimental examinations gained insight of the superior operating behaviour and the further advantages of the HT-PEMFC in comparison to the LT-PEMFC were crucial for the construction of a simulation model for a single HT-PEM fuel cell in the theoretical part of this thesis, that also should be suitable as process simulation model for the computer based development of a virtual fuel cell within the interdisciplinary project ''Virtual Fuel Cell'' at the TU Darmstadt. The model is a numerical 2D ''along the channel'' - model, that was constructed with the finite element software COMSOL Multiphysics (version 3.5 a). The stationary, one phase model comprises altogether ten dependent variables in seven application modules in a highly complex, coupled non linear system of equations with 33713 degrees of freedom (1675 rectangle elements with 1768 nodes). The simulation model describes the mass transport processes and the electro-chemical reactions in a HT-PEM fuel cell with good accuracy, the model validation by comparing the model results with experimental data could be proved. So the 2D-model is basically suitable as process simulation model for the projecting of a virtual HT-PEM fuel cell. (orig.)
Biomolecular modelling and simulations
Karabencheva-Christova, Tatyana
2014-01-01
Published continuously since 1944, the Advances in Protein Chemistry and Structural Biology series is the essential resource for protein chemists. Each volume brings forth new information about protocols and analysis of proteins. Each thematically organized volume is guest edited by leading experts in a broad range of protein-related topics. Describes advances in biomolecular modelling and simulations Chapters are written by authorities in their field Targeted to a wide audience of researchers, specialists, and students The information provided in the volume is well supported by a number of high quality illustrations, figures, and tables.
Photovoltaic array performance simulation models
Energy Technology Data Exchange (ETDEWEB)
Menicucci, D. F.
1986-09-15
The experience of the solar industry confirms that, despite recent cost reductions, the profitability of photovoltaic (PV) systems is often marginal and the configuration and sizing of a system is a critical problem for the design engineer. Construction and evaluation of experimental systems are expensive and seldom justifiable. A mathematical model or computer-simulation program is a desirable alternative, provided reliable results can be obtained. Sandia National Laboratories, Albuquerque (SNLA), has been studying PV-system modeling techniques in an effort to develop an effective tool to be used by engineers and architects in the design of cost-effective PV systems. This paper reviews two of the sources of error found in previous PV modeling programs, presents the remedies developed to correct these errors, and describes a new program that incorporates these improvements.
Simplified simulation of an experimental fast reactor plant
International Nuclear Information System (INIS)
Fujii, Masaaki; Fujita, Minoru.
1978-01-01
Purposes of the simulation are to study the dynamic behavior of a liquid metal-cooled experimental fast breeder reactor plant and to design the control system of the reactor plant by modified-RAPID (Reactor and Plant Integrated Dynamics) computer program. As for the plant model, the Japan Experimental Fast Reactor ''Joyo'' was referred to approximately. This computer program is designed for the calculation of steady-state and transient temperatures in a FBR plant; which is described by a model consisting of the core, upper and lower plenums, an intermediate heat exchanger, an air dump heat exchanger, primary-secondary and tertiary coolant systems and connecting pipes. The basic equations are solved numerically by finite difference approximation. The mathematical model for an experimental FBR plant is useful for the design of the control system of FBR plants. The results of numerical simulation showed that the proportional change in the flow rates of the primary and secondary coolant loops provides good performance in relation to the stepped change in the power level. (J.P.N.)
Experimental Simulations to Understand the Lunar and Martian Surficial Processes
Zhao, Y. Y. S.; Li, X.; Tang, H.; Li, Y.; Zeng, X.; Chang, R.; Li, S.; Zhang, S.; Jin, H.; Mo, B.; Li, R.; Yu, W.; Wang, S.
2016-12-01
In support with China's Lunar and Mars exploration programs and beyond, our center is dedicated to understand the surficial processes and environments of planetary bodies. Over the latest several years, we design, build and optimize experimental simulation facilities and utilize them to test hypotheses and evaluate affecting mechanisms under controlled conditions particularly relevant to the Moon and Mars. Among the fundamental questions to address, we emphasize on five major areas: (1) Micrometeorites bombardment simulation to evaluate the formation mechanisms of np-Fe0 which was found in lunar samples and the possible sources of Fe. (2) Solar wind implantation simulation to evaluate the alteration/amorphization/OH or H2O formation on the surface of target minerals or rocks. (3) Dusts mobility characteristics on the Moon and other planetary bodies by excitation different types of dust particles and measuring their movements. (4) Mars basaltic soil simulant development (e.g., Jining Martian Soil Simulant (JMSS-1)) and applications for scientific/engineering experiments. (5) Halogens (Cl and Br) and life essential elements (C, H, O, N, P, and S) distribution and speciation on Mars during surficial processes such as sedimentary- and photochemical- related processes. Depending on the variables of interest, the simulation systems provide flexibility to vary source of energy, temperature, pressure, and ambient gas composition in the reaction chambers. Also, simulation products can be observed or analyzed in-situ by various analyzer components inside the chamber, without interrupting the experimental conditions. In addition, behavior of elements and isotopes during certain surficial processes (e.g., evaporation, dissolution, etc.) can be theoretically predicted by our theoretical geochemistry group with thermodynamics-kinetics calculation and modeling, which supports experiment design and result interpretation.
Electrochemical desalination of bricks - Experimental and modeling
DEFF Research Database (Denmark)
Skibsted, Gry; Ottosen, Lisbeth M.; Jensen, Pernille Erland
2015-01-01
Chlorides, nitrates and sulfates play an important role in the salt-decay of porous materials in buildings and monuments. Electrochemical desalination is a technology able to remove salts from such porous materials in order to stop or prevent the decay. In this paper, experimental and numerical......-contaminated bricks with respect to the monovalent ions is discussed. Comparison between the experimental and the simulation results showed that the proposed numerical model is able to predict electrochemical desalination treatments with remarkable accuracy, and it can be used as a predictive tool...
Verifying and Validating Simulation Models
Energy Technology Data Exchange (ETDEWEB)
Hemez, Francois M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-02-23
This presentation is a high-level discussion of the Verification and Validation (V&V) of computational models. Definitions of V&V are given to emphasize that “validation” is never performed in a vacuum; it accounts, instead, for the current state-of-knowledge in the discipline considered. In particular comparisons between physical measurements and numerical predictions should account for their respective sources of uncertainty. The differences between error (bias), aleatoric uncertainty (randomness) and epistemic uncertainty (ignorance, lack-of- knowledge) are briefly discussed. Four types of uncertainty in physics and engineering are discussed: 1) experimental variability, 2) variability and randomness, 3) numerical uncertainty and 4) model-form uncertainty. Statistical sampling methods are available to propagate, and analyze, variability and randomness. Numerical uncertainty originates from the truncation error introduced by the discretization of partial differential equations in time and space. Model-form uncertainty is introduced by assumptions often formulated to render a complex problem more tractable and amenable to modeling and simulation. The discussion concludes with high-level guidance to assess the “credibility” of numerical simulations, which stems from the level of rigor with which these various sources of uncertainty are assessed and quantified.
Model improvements to simulate charging in SEM
Arat, K. T.; Klimpel, T.; Hagen, C. W.
2018-03-01
Charging of insulators is a complex phenomenon to simulate since the accuracy of the simulations is very sensitive to the interaction of electrons with matter and electric fields. In this study, we report model improvements for a previously developed Monte-Carlo simulator to more accurately simulate samples that charge. The improvements include both modelling of low energy electron scattering and charging of insulators. The new first-principle scattering models provide a more realistic charge distribution cloud in the material, and a better match between non-charging simulations and experimental results. Improvements on charging models mainly focus on redistribution of the charge carriers in the material with an induced conductivity (EBIC) and a breakdown model, leading to a smoother distribution of the charges. Combined with a more accurate tracing of low energy electrons in the electric field, we managed to reproduce the dynamically changing charging contrast due to an induced positive surface potential.
Impulse pumping modelling and simulation
International Nuclear Information System (INIS)
Pierre, B; Gudmundsson, J S
2010-01-01
Impulse pumping is a new pumping method based on propagation of pressure waves. Of particular interest is the application of impulse pumping to artificial lift situations, where fluid is transported from wellbore to wellhead using pressure waves generated at wellhead. The motor driven element of an impulse pumping apparatus is therefore located at wellhead and can be separated from the flowline. Thus operation and maintenance of an impulse pump are facilitated. The paper describes the different elements of an impulse pumping apparatus, reviews the physical principles and details the modelling of the novel pumping method. Results from numerical simulations of propagation of pressure waves in water-filled pipelines are then presented for illustrating impulse pumping physical principles, and validating the described modelling with experimental data.
Experimental and simulated strength of spot welds
DEFF Research Database (Denmark)
Nielsen, Chris Valentin; Bennedbæk, Rune A.K.; Larsen, Morten B.
2014-01-01
Weld strength testing of single spots in DP600 steel is presented for the three typical testing procedures, i.e. tensile-shear, cross-tension and peel testing. Spot welds are performed at two sets of welding parameters and strength testing under these conditions is presented by load......-elongation curves revealing the maximum load and the elongation at break. Welding and strength testing is simulated by SORPAS® 3D, which allows the two processes to be prepared in a combined simulation, such that the simulated welding properties are naturally applied to the simulation of strength testing. Besides...... the size and shape of the weld nugget, these properties include the new strength of the material in the weld and the heat affected zone based on the predicted hardness resulting from microstructural phase changes simulated during cooling of the weld before strength testing. Comparisons between overall...
International Nuclear Information System (INIS)
Fitton, N; Datta, A; Hastings, A; Kuhnert, M; Smith, P; Topp, C F E; Cloy, J M; Rees, R M; Cardenas, L M; Williams, J R; Smith, K; Chadwick, D
2014-01-01
The United Kingdom currently reports nitrous oxide emissions from agriculture using the IPCC default Tier 1 methodology. However Tier 1 estimates have a large degree of uncertainty as they do not account for spatial variations in emissions. Therefore biogeochemical models such as DailyDayCent (DDC) are increasingly being used to provide a spatially disaggregated assessment of annual emissions. Prior to use, an assessment of the ability of the model to predict annual emissions should be undertaken, coupled with an analysis of how model inputs influence model outputs, and whether the modelled estimates are more robust that those derived from the Tier 1 methodology. The aims of the study were (a) to evaluate if the DailyDayCent model can accurately estimate annual N 2 O emissions across nine different experimental sites, (b) to examine its sensitivity to different soil and climate inputs across a number of experimental sites and (c) to examine the influence of uncertainty in the measured inputs on modelled N 2 O emissions. DailyDayCent performed well across the range of cropland and grassland sites, particularly for fertilized fields indicating that it is robust for UK conditions. The sensitivity of the model varied across the sites and also between fertilizer/manure treatments. Overall our results showed that there was a stronger correlation between the sensitivity of N 2 O emissions to changes in soil pH and clay content than the remaining input parameters used in this study. The lower the initial site values for soil pH and clay content, the more sensitive DDC was to changes from their initial value. When we compared modelled estimates with Tier 1 estimates for each site, we found that DailyDayCent provided a more accurate representation of the rate of annual emissions. (paper)
Energy Technology Data Exchange (ETDEWEB)
Thiers, Stephane; Aoun, Bernard; Peuportier, Bruno [MINES ParisTech, CEP - Centre Energetique et Procedes, 60 Boulevard St Michel, 75272 Paris Cedex 06 (France)
2010-06-15
Cogeneration provides heat and power in a more efficient way than separate production. Micro-cogeneration (micro-CHP) is an emerging solution for the improvement of energy and environmental assessments of residential buildings. A wood pellet Stirling engine micro-CHP unit has been studied in order to characterize its annual performance when integrated to a building. First, through a test bench experiment, both transient and steady state behaviors of the micro-CHP unit have been characterized and modeled. Then a more complete model representing a hot water and heating system including the micro-CHP unit and a stratified storage tank has been carried out. This model has been coupled to a building model. A sensitivity analysis by simulation shows that the dimensioning of different elements of the system strongly influences its global energy performance. (author)
Directory of Open Access Journals (Sweden)
Fukang Ma
2017-05-01
Full Text Available The scavenging process for opposed-piston folded-cranktrain (OPFC diesel engines can be described by the time evolution of the in-cylinder and exhaust chamber residual gas rates. The relation curve of in-cylinder and exhaust chamber residual gas rate is called scavenging profile, which is calculated through the changes of in-cylinder and exhaust chamber gas compositions determined by computational fluid dynamics (CFD simulation. The scavenging profile is used to calculate the scavenging process by mono-dimensional (1D simulation. The tracer gas method (TGM is employed to validate the accuracy of the scavenging profile. At the same time, the gas exchange performance under different intake and exhaust state parameters was examined based on the TGM. The results show that the scavenging process from 1D simulation and experiment match well, which means the scavenging model obtained by CFD simulation performs well and validation of its effectiveness by TGM is possible. The difference between intake and exhaust pressure has a significant positive effect on the gas exchange performance and trapped gas mass, but the pressure difference has little effect on the scavenging efficiency and the trapped air mass if the delivery ratio exceeds 1.4.
Using IMPRINT to Guide Experimental Design with Simulated Task Environments
2015-06-18
USING IMPRINT TO GUIDE EXPERIMENTAL DESIGN OF SIMULATED TASK ENVIRONMENTS THESIS Gregory...ENG-MS-15-J-052 USING IMPRINT TO GUIDE EXPERIMENTAL DESIGN WITH SIMULATED TASK ENVIRONMENTS THESIS Presented to the Faculty Department...Civilian, USAF June 2015 DISTRIBUTION STATEMENT A. APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. AFIT-ENG-MS-15-J-052 USING IMPRINT
International Nuclear Information System (INIS)
Vella, G.; Maio, P.A. Di; Giammusso, R.; Tincani, A.; Orco, G. Dell
2006-01-01
Within the framework of the activities promoted by European Fusion Development Agreement on the technology of the Helium Cooled Pebble Bed Test Blanket Module to be irradiated in one of the ITER equatorial ports, attention has been focused on the theoretical modelling of the thermo-mechanical constitutive behaviour of both beryllium and lithiated ceramics pebble beds, that are envisaged to act respectively as neutron multiplier and tritium breeder. The thermo-mechanical behaviour of the pebble beds and their nuclear performances in terms of tritium production depend on the reactor relevant conditions (heat flux and neutron wall load), the pebble sizes and the breeder cell geometries (bed thickness, pebble packing factor, bed overall thermal conductivity). ENEA-Brasimone and the Department of Nuclear Engineering (DIN) of the Palermo University have performed intense research activities intended to investigate fusion-relevant pebble bed thermo-mechanical behaviour by adopting both experimental and theoretical approaches. In particular, ENEA has carried out several experimental campaigns on small scale mock-ups tested in out-of-pile conditions, while DIN has developed a proper constitutive model that has been implemented on commercial FEM code, for the prediction of the thermal and mechanical performances of fusion-relevant pebble beds and for the comparison with the experimental results of the ENEA tests. In that framework, HELICA mock-up has been set-up and tested to investigate the behaviour of pebble bed in reactor-relevant geometries, providing useful data sets to be numerically reproduced by means of the DIN constitutive model, contributing to its assessment. The paper presents the constitutive model developed and the main experimental results of two test campaigns on HELICA mock-up carried out at HE-FUS 3 facility of ENEA Brasimone, the geometry of the mock-up, the adopted thermal and mechanical boundary conditions and the test operating conditions. The most
Simulant-material experimental investigation of flow dynamics in the CRBR Upper-Core Structure
International Nuclear Information System (INIS)
Wilhelm, D.; Starkovich, V.S.; Chapyak, E.J.
1982-09-01
The results of a simulant-material experimental investigation of flow dynamics in the Clinch River Breeder Reactor (CRBR) Upper Core Structure are described. The methodology used to design the experimental apparatus and select test conditions is detailed. Numerous comparisons between experimental data and SIMMER-II Code calculations are presented with both advantages and limitations of the SIMMER modeling features identified
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.
Parra-Robles, J; Ajraoui, S; Deppe, M H; Parnell, S R; Wild, J M
2010-06-01
Models of lung acinar geometry have been proposed to analytically describe the diffusion of (3)He in the lung (as measured with pulsed gradient spin echo (PGSE) methods) as a possible means of characterizing lung microstructure from measurement of the (3)He ADC. In this work, major limitations in these analytical models are highlighted in simple diffusion weighted experiments with (3)He in cylindrical models of known geometry. The findings are substantiated with numerical simulations based on the same geometry using finite difference representation of the Bloch-Torrey equation. The validity of the existing "cylinder model" is discussed in terms of the physical diffusion regimes experienced and the basic reliance of the cylinder model and other ADC-based approaches on a Gaussian diffusion behaviour is highlighted. The results presented here demonstrate that physical assumptions of the cylinder model are not valid for large diffusion gradient strengths (above approximately 15 mT/m), which are commonly used for (3)He ADC measurements in human lungs. (c) 2010 Elsevier Inc. All rights reserved.
Real-time numerical simulation with high efficiency for an experimental reactor system
International Nuclear Information System (INIS)
Ding Shuling; Li Fu; Li Sifeng; Chu Xinyuan
2006-01-01
The paper presents a systematic and efficient method for numerical real-time simulation of an experimental reactor. The reactor models were built based on the physical characteristics of the experimental reactor, and several real-time simulation approaches were discussed and compared in the paper. How to implement the real-time reactor simulation system in Windows platform for the sake of hardware-in-loop experiment for the reactor power control system was discussed. (authors)
Adjustment model of thermoluminescence experimental data
International Nuclear Information System (INIS)
Moreno y Moreno, A.; Moreno B, A.
2002-01-01
This model adjusts the experimental results for thermoluminescence according to the equation: I (T) = I (a i * exp (-1/b i * (T-C i )) where: a i , b i , c i are the i-Th peak adjusted to a gaussian curve. The adjustments of the curve can be operated manual or analytically using the macro function and the solver.xla complement installed previously in the computational system. In this work it is shown: 1. The information of experimental data from a LiF curve obtained from the Physics Institute of UNAM which the data adjustment model is operated in the macro type. 2. A LiF curve of four peaks obtained from Harshaw information simulated in Microsoft Excel, discussed in previous works, as a reference not in macro. (Author)
Notes on modeling and simulation
Energy Technology Data Exchange (ETDEWEB)
Redondo, Antonio [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-03-10
These notes present a high-level overview of how modeling and simulation are carried out by practitioners. The discussion is of a general nature; no specific techniques are examined but the activities associated with all modeling and simulation approaches are briefly addressed. There is also a discussion of validation and verification and, at the end, a section on why modeling and simulation are useful.
Energy Technology Data Exchange (ETDEWEB)
Ricciardi, G.
2008-10-15
The designing of a pressurized water reactor core subjected to seismic loading, is a major concern of the nuclear industry. We propose, in this PhD report, to establish the global behaviour equations of the core, in term of a porous medium. Local equations of fluid and structure are space averaged on a control volume, thus we define an equivalent fluid and an equivalent structure, of which unknowns are defined on the whole space. The non-linear fuel assemblies behaviour is modelled by a visco-elastic constitutive law. The fluid-structure coupling is accounted for by a body force, the expression of that force is based on empirical formula of fluid forces acting on a tube subject to an axial flow. The resulting equations are solved using a finite element method. A validation of the model, on three experimental device, is proposed. The first one presents two fuel assemblies subjected to axial flow. One of the two fuel assemblies is deviated from its position of equilibrium and released, while the other is at rest. The second one presents a six assemblies row, immersed in water, placed on a shaking table that can simulate seismic loading. Finally, the last one presents nine fuel assemblies network, arranged in a three by three, subject to an axial flow. The displacement of the central fuel assembly is imposed. The simulations are in agreement with the experiments, the model reproduces the influence of the flow of fluid on the dynamics and coupling of the fuel assemblies. (author)
Simulation of Experimental Background using FLUKA
Energy Technology Data Exchange (ETDEWEB)
Rokni, Sayed
1999-05-11
In November 1997, Experiment T423 began acquiring data with the intentions of understanding the energy spectra of high-energy neutrons generated in the interaction of electrons with lead. The following describes a series of FLUKA simulations studying (1) particle yields in the absence of all background; (2) the background caused from scattering in the room; (3) the effects of the thick lead shielding which surrounded the detector; (4) the sources of neutron background created in this lead shielding; and (5) the ratio of the total background to the ideal yield. In each case, particular attention is paid to the neutron yield.
Experimental models of developmental hypothyroidism.
Argumedo, G S; Sanz, C R; Olguín, H J
2012-02-01
Hypothyroidism is a systemic disease resulting from either thyroid gland's anatomical and functional absence or lack of hypophyseal stimulation, both of which can lead to deficiency in thyroid hormone (TH) production. TH is essential for human and animal development, growth, and function of multiple organs. Children with deficient TH can develop alterations in central nervous system (CNS), striated muscle, bone tissue, liver, bone marrow, and cardiorespiratory system. Among the clinical outlook are signs like breathing difficulty, cardiac insufficiency, dysphagia, and repeated bronchial aspiration, constipation, muscle weakness, cognitive alterations, cochlear dysfunction, reduced height, defects in temperature regulation, anaemia, jaundice, susceptibility to infection, and others. Experimental and clinical studies have shown that TH is very essential for normal brain development. Other research work based on mice pointed out that a reduced level of TH in pregnant mother leads to congenital hypothyroidism in animal models and it is associated with mental retardation, deep neurologic deficiency that impacts on cognitive, learning, and memory functions. The principal experimental model studies that have focused on hypothyroidism are reviewed in this study. This is important on considering the fact that almost all animal species require thyroid hormones for their metabolism. © Georg Thieme Verlag KG Stuttgart · New York.
Experimental simulation of retrodirective cross-eye jamming
CSIR Research Space (South Africa)
Du Plessis, WP
2010-01-01
Full Text Available Experimental measurements that accurately simulate the effect of a retrodirective cross-eye jammer on a monopulse radar are described. The accuracy of a recently published extended analysis of retrodirective crosseye jamming and the limitations...
International Nuclear Information System (INIS)
Intriligator, D.S.; Steele, G.R.
1985-01-01
Laboratory experiments have been performed that show the effect on the electron temperature of inserting a spherical conducting model, larger than the Debye length, into a free-streaming high-energy (1 kv) unmagnetized hydrogen plasma. These experiments are the first electron temperature experiments conducted at energies and compositions directly relevant to solar wind and astrophysical plasma phenomena. The incident plasma parameters were held constant. A large number of axial profiles of the electron temperature ratios T/sub e//sub in// T/sub e//sub out/ behind the model downstream in the model wake are presented. A rigorous statistical approach is used in the analysis of the electron temperature ratio data in both our experimental laboratory data and in our reanalysis of the published data of others. The following new results ae obtained: (1) In energetic plasma flow there is no overall temperature enhancement in the near wake since the best fit to the T/sub e//sub i/n/ T/sub e//sub out/ data is a horizontal straight line having a mean value of 1.05; (2) No statistically significant electron temperature enhancement peaks or depressions exist in the near-wake region behind a model at zero potential in a high-energy plasma even at distances less than or equal to Ma, where M is the acoustic Mach number and a is the model radius. This implies a ''filling in'' of electrons in the wake region which may be due to the higher mobility of these energetic electrons. This mechanism may permit the solar wind electrons to significantly contribute to the maintenance of the nightside ionosphere at Venus
Simulation Model of a Transient
DEFF Research Database (Denmark)
Jauch, Clemens; Sørensen, Poul; Bak-Jensen, Birgitte
2005-01-01
This paper describes the simulation model of a controller that enables an active-stall wind turbine to ride through transient faults. The simulated wind turbine is connected to a simple model of a power system. Certain fault scenarios are specified and the turbine shall be able to sustain operati...
International Nuclear Information System (INIS)
Garnier-Laplace, J.
1990-10-01
Uptake and retention of 110m Ag are quantified from laboratory studies carried out on an experimental freshwater ecosystem composed by two abiotic units, water and sediment, and by four trophic levels: primary producer (Scenedesmus obliquus), first order consumers (Daphnia magna, Gammarus pulex, Chrionomus sp.), second order consumer (Cyprinus carpio) and third order one (Salmo trutta). The chosen analytical process consists in expressing each transfer by a mathematical equation which formulation is based on a theoric analysis. Experiments allow to calibrate parameters of these equations for each unit of the food chain. All experimental data concerning 110m Ag uptake emphasize the radioprotection implications of this radioelement, because of the high values of the estimated radioecological parameters. On the basis of the results obtained, a determinist mathematical model has been conceived to simulate the radionuclide distribution in the food chain as a function of a chronic or acute contamination mode. Its application gives the development with time of the mean 110m Ag concentration values for each trophic level. The first approaches based on the analysis of the results of field studies, carried out on ecosystems affected by chronic pollution (Rhone river) or acute one (as a consequence of the Chernobyl accident), give to the model an important explicative and global predictive quality. The age of the fish, their dietary habits which vary according to the annual cycle of the prey species and with theirposition in the food chain, appear such as essential parameters. The trophic pathway is clearly predominant whatever the contamination mode and, explains, for acute exposure, why accumulation of 110m Ag can be prolonged for a long time after the surrounding environment contamination [fr
Novel Experimental Simulations of the Atmospheric Injection of Meteoric Metals
Energy Technology Data Exchange (ETDEWEB)
Gómez Martín, J. C.; Bones, D. L.; Carrillo-Sánchez, J. D.; James, A. D.; Plane, J. M. C. [School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT (United Kingdom); Trigo-Rodríguez, J. M. [Meteorites, Minor Bodies and Planetary Science Group, Institute of Space Sciences (CSIC-IEEC). Campus UAB, C/Can Magrans s/n, E-08193 Cerdanyola del Vallés (Barcelona) (Spain); Fegley, B. Jr., E-mail: J.M.C.Plane@leeds.ac.uk [Washington University, St. Louis, MO (United States)
2017-02-20
A newly developed laboratory, Meteoric Ablation Simulator (MASI), is used to test model predictions of the atmospheric ablation of interplanetary dust particles (IDPs) with experimental Na, Fe, and Ca vaporization profiles. MASI is the first laboratory setup capable of performing time-resolved atmospheric ablation simulations, by means of precision resistive heating and atomic laser-induced fluorescence detection. Experiments using meteoritic IDP analogues show that at least three mineral phases (Na-rich plagioclase, metal sulfide, and Mg-rich silicate) are required to explain the observed appearance temperatures of the vaporized elements. Low melting temperatures of Na-rich plagioclase and metal sulfide, compared to silicate grains, preclude equilibration of all the elemental constituents in a single melt. The phase-change process of distinct mineral components determines the way in which Na and Fe evaporate. Ca evaporation is dependent on particle size and on the initial composition of the molten silicate. Measured vaporized fractions of Na, Fe, and Ca as a function of particle size and speed confirm differential ablation (i.e., the most volatile elements such as Na ablate first, followed by the main constituents Fe, Mg, and Si, and finally the most refractory elements such as Ca). The Chemical Ablation Model (CABMOD) provides a reasonable approximation to this effect based on chemical fractionation of a molten silicate in thermodynamic equilibrium, even though the compositional and geometric description of IDPs is simplistic. Improvements in the model are required in order to better reproduce the specific shape of the elemental ablation profiles.
Catalytic Reactive Distillation for the Esterification Process: Experimental and Simulation
Directory of Open Access Journals (Sweden)
M. Mallaiah
2017-10-01
Full Text Available In the present study, methyl acetate has been synthesized using esterification of acetic acid with methanol in a continuous packed bed catalytic reactive distillation col- umn in the presence of novel Indion 180 ion exchange resin solid catalyst. The experiments were conducted at various operating conditions like reboiler temperature, reflux ratio, and different feed flow rates of the acetic acid and methanol. The non-ideal pseudo-homogeneous kinetic model has been developed for esterification of acetic acid with methanol in the presence of Indion 180 catalyst. The developed kinetic model was used for the simulation of the reactive distillation column for the synthesis of methyl acetate using equilibrium stage model in Aspen Plus version 7.3. The simulation results were compared with experimental results, and found that there is a good agreement between them. The sensitivity analyses were also carried out for the different parameters of bot- tom flow rate, feed temperatures of acetic acid and methanol, and feed flow rate of acetic acid and methanol.
Cognitive models embedded in system simulation models
International Nuclear Information System (INIS)
Siegel, A.I.; Wolf, J.J.
1982-01-01
If we are to discuss and consider cognitive models, we must first come to grips with two questions: (1) What is cognition; (2) What is a model. Presumably, the answers to these questions can provide a basis for defining a cognitive model. Accordingly, this paper first places these two questions into perspective. Then, cognitive models are set within the context of computer simulation models and a number of computer simulations of cognitive processes are described. Finally, pervasive issues are discussed vis-a-vis cognitive modeling in the computer simulation context
Validity of microgravity simulation models on earth
DEFF Research Database (Denmark)
Regnard, J; Heer, M; Drummer, C
2001-01-01
Many studies have used water immersion and head-down bed rest as experimental models to simulate responses to microgravity. However, some data collected during space missions are at variance or in contrast with observations collected from experimental models. These discrepancies could reflect...... incomplete knowledge of the characteristics inherent to each model. During water immersion, the hydrostatic pressure lowers the peripheral vascular capacity and causes increased thoracic blood volume and high vascular perfusion. In turn, these changes lead to high urinary flow, low vasomotor tone, and a high...
General introduction to simulation models
DEFF Research Database (Denmark)
Hisham Beshara Halasa, Tariq; Boklund, Anette
2012-01-01
trials. However, if simulation models would be used, good quality input data must be available. To model FMD, several disease spread models are available. For this project, we chose three simulation model; Davis Animal Disease Spread (DADS), that has been upgraded to DTU-DADS, InterSpread Plus (ISP......Monte Carlo simulation can be defined as a representation of real life systems to gain insight into their functions and to investigate the effects of alternative conditions or actions on the modeled system. Models are a simplification of a system. Most often, it is best to use experiments and field...... trials to investigate the effect of alternative conditions or actions on a specific system. Nonetheless, field trials are expensive and sometimes not possible to conduct, as in case of foot-and-mouth disease (FMD). Instead, simulation models can be a good and cheap substitute for experiments and field...
Energy Technology Data Exchange (ETDEWEB)
Munoz-Cobo, Jose L., E-mail: jlcobos@iqn.upv.es [Instituto de Ingenieria Energetica, Universidad Politecnica de Valencia, Valencia (Spain); Chiva, Sergio [Department of Mechanical Engineering and Construction, Universitat Jaume I, Castellon (Spain); Essa, Mohamed Ali Abd El Aziz [Instituto de Ingenieria Energetica, Universidad Politecnica de Valencia, Valencia (Spain); Mendes, Santos [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico)
2012-01-15
Highlights: Black-Right-Pointing-Pointer We have simulated bubbly flow in vertical pipes by coupling a Lagrangian model to an Eulerian one, and to a 3D random walk model. Black-Right-Pointing-Pointer A set of experiments in a vertical column with isothermal co-current two phase flow have been performed and used to validate the previous model. Black-Right-Pointing-Pointer We have investigated the influence of the turbulence induced by the bubbles on the results. Black-Right-Pointing-Pointer Comparison of experimental and computed results has been performed for different boundary conditions. - Abstract: A set of two phase flow experiments for different conditions ranging from bubbly flow to cap/slug flow have been performed under isothermal concurrent upward air-water flow conditions in a vertical column of 3 m height. Special attention in these experiments was devoted to the transition from bubbly to cap/slug flow. The interfacial velocity of the bubbles and the void fraction distribution was obtained using 2 and 4 sensors conductivity probes. Numerical simulations of these experiments for bubbly flow conditions were performed by coupling a Lagrangian code with an Eulerian one. The first one tracks the 3D motion of the individual bubbles in cylindrical coordinates (r, {phi}, z) inside the fluid field under the action of the following forces: buoyancy, drag, lift, wall lubrication. Also we have incorporated a 3D stochastic differential equation model to account for the random motion of the individual bubbles in the turbulent velocity field of the carrier liquid. Also we have considered the deformations undergone by the bubbles when they touch the walls of the pipe and are compressed until they rebound. The velocity and turbulence fields of the liquid phase were computed by solving the time dependent conservation equations in its Reynolds Averaged Transport Equation form (RANS). The turbulent kinetic energy k, and the dissipation rate {epsilon} transport equations
International Nuclear Information System (INIS)
Muñoz-Cobo, José L.; Chiva, Sergio; Essa, Mohamed Ali Abd El Aziz; Mendes, Santos
2012-01-01
Highlights: ► We have simulated bubbly flow in vertical pipes by coupling a Lagrangian model to an Eulerian one, and to a 3D random walk model. ► A set of experiments in a vertical column with isothermal co-current two phase flow have been performed and used to validate the previous model. ► We have investigated the influence of the turbulence induced by the bubbles on the results. ► Comparison of experimental and computed results has been performed for different boundary conditions. - Abstract: A set of two phase flow experiments for different conditions ranging from bubbly flow to cap/slug flow have been performed under isothermal concurrent upward air–water flow conditions in a vertical column of 3 m height. Special attention in these experiments was devoted to the transition from bubbly to cap/slug flow. The interfacial velocity of the bubbles and the void fraction distribution was obtained using 2 and 4 sensors conductivity probes. Numerical simulations of these experiments for bubbly flow conditions were performed by coupling a Lagrangian code with an Eulerian one. The first one tracks the 3D motion of the individual bubbles in cylindrical coordinates (r, φ, z) inside the fluid field under the action of the following forces: buoyancy, drag, lift, wall lubrication. Also we have incorporated a 3D stochastic differential equation model to account for the random motion of the individual bubbles in the turbulent velocity field of the carrier liquid. Also we have considered the deformations undergone by the bubbles when they touch the walls of the pipe and are compressed until they rebound. The velocity and turbulence fields of the liquid phase were computed by solving the time dependent conservation equations in its Reynolds Averaged Transport Equation form (RANS). The turbulent kinetic energy k, and the dissipation rate ε transport equations were simultaneously solved using the k, epsilon model in a (r, z) grid by the finite volume method and the
Experimental models of liver fibrosis.
Yanguas, Sara Crespo; Cogliati, Bruno; Willebrords, Joost; Maes, Michaël; Colle, Isabelle; van den Bossche, Bert; de Oliveira, Claudia Pinto Marques Souza; Andraus, Wellington; Alves, Venâncio Avancini Ferreira; Leclercq, Isabelle; Vinken, Mathieu
2016-05-01
Hepatic fibrosis is a wound healing response to insults and as such affects the entire world population. In industrialized countries, the main causes of liver fibrosis include alcohol abuse, chronic hepatitis virus infection and non-alcoholic steatohepatitis. A central event in liver fibrosis is the activation of hepatic stellate cells, which is triggered by a plethora of signaling pathways. Liver fibrosis can progress into more severe stages, known as cirrhosis, when liver acini are substituted by nodules, and further to hepatocellular carcinoma. Considerable efforts are currently devoted to liver fibrosis research, not only with the goal of further elucidating the molecular mechanisms that drive this disease, but equally in view of establishing effective diagnostic and therapeutic strategies. The present paper provides a state-of-the-art overview of in vivo and in vitro models used in the field of experimental liver fibrosis research.
Decentralized adaptive control of manipulators - Theory, simulation, and experimentation
Seraji, Homayoun
1989-01-01
The author presents a simple decentralized adaptive-control scheme for multijoint robot manipulators based on the independent joint control concept. The control objective is to achieve accurate tracking of desired joint trajectories. The proposed control scheme does not use the complex manipulator dynamic model, and each joint is controlled simply by a PID (proportional-integral-derivative) feedback controller and a position-velocity-acceleration feedforward controller, both with adjustable gains. Simulation results are given for a two-link direct-drive manipulator under adaptive independent joint control. The results illustrate trajectory tracking under coupled dynamics and varying payload. The proposed scheme is implemented on a MicroVAX II computer for motion control of the three major joints of a PUMA 560 arm. Experimental results are presented to demonstrate that trajectory tracking is achieved despite coupled nonlinear joint dynamics.
Simulation-based optimal Bayesian experimental design for nonlinear systems
Huan, Xun
2013-01-01
The optimal selection of experimental conditions is essential to maximizing the value of data for inference and prediction, particularly in situations where experiments are time-consuming and expensive to conduct. We propose a general mathematical framework and an algorithmic approach for optimal experimental design with nonlinear simulation-based models; in particular, we focus on finding sets of experiments that provide the most information about targeted sets of parameters.Our framework employs a Bayesian statistical setting, which provides a foundation for inference from noisy, indirect, and incomplete data, and a natural mechanism for incorporating heterogeneous sources of information. An objective function is constructed from information theoretic measures, reflecting expected information gain from proposed combinations of experiments. Polynomial chaos approximations and a two-stage Monte Carlo sampling method are used to evaluate the expected information gain. Stochastic approximation algorithms are then used to make optimization feasible in computationally intensive and high-dimensional settings. These algorithms are demonstrated on model problems and on nonlinear parameter inference problems arising in detailed combustion kinetics. © 2012 Elsevier Inc.
Comparing TCV experimental VDE responses with DINA code simulations
Favez, J.-Y.; Khayrutdinov, R. R.; Lister, J. B.; Lukash, V. E.
2002-02-01
The DINA free-boundary equilibrium simulation code has been implemented for TCV, including the full TCV feedback and diagnostic systems. First results showed good agreement with control coil perturbations and correctly reproduced certain non-linear features in the experimental measurements. The latest DINA code simulations, presented in this paper, exploit discharges with different cross-sectional shapes and different vertical instability growth rates which were subjected to controlled vertical displacement events (VDEs), extending previous work with the DINA code on the DIII-D tokamak. The height of the TCV vessel allows observation of the non-linear evolution of the VDE growth rate as regions of different vertical field decay index are crossed. The vertical movement of the plasma is found to be well modelled. For most experiments, DINA reproduces the S-shape of the vertical displacement in TCV with excellent precision. This behaviour cannot be modelled using linear time-independent models because of the predominant exponential shape due to the unstable pole of any linear time-independent model. The other most common equilibrium parameters like the plasma current Ip, the elongation κ, the triangularity δ, the safety factor q, the ratio between the averaged plasma kinetic pressure and the pressure of the poloidal magnetic field at the edge of the plasma βp, and the internal self inductance li also show acceptable agreement. The evolution of the growth rate γ is estimated and compared with the evolution of the closed-loop growth rate calculated with the RZIP linear model, confirming the origin of the observed behaviour.
Comparing TCV experimental VDE responses with DINA code simulations
International Nuclear Information System (INIS)
Favez, J.Y.; Khayrutdinov, J.B.; Lister, J.B.; Lukash, V.E.
2001-10-01
The DINA free-boundary equilibrium simulation code has been implemented for TCV, including the full TCV feedback and diagnostic systems. First results showed good agreement with control coil perturbations and correctly reproduced certain non-linear features in the experimental measurements. The latest DINA code simulations, presented in this paper, exploit discharges with different cross- sectional shapes and different vertical instability growth rates which were subjected to controlled Vertical Displacement Events, extending previous work with the DINA code on the DIII-D tokamak. The height of the TCV vessel allows observation of the non- linear evolution of the VDE growth rate as regions of different vertical field decay index are crossed. The vertical movement of the plasma is found to be well modelled. For most experiments, DINA reproduces the S-shape of the vertical displacement in TCV with excellent precision. This behaviour cannot be modelled using linear time-independent models because of the predominant exponential shape due to the unstable pole of any linear time-independent model. The other most common equilibrium parameters like the plasma current Ip, the elongation K, the triangularity d, the safety factor q, the ratio between the averaged plasma kinetic pressure and the pressure of the poloidal magnetic field at the edge of the plasma bp and the internal self inductance l also show acceptable agreement. The evolution of the growth rate g is estimated and compared with the evolution of the closed loop growth rate calculated with the RZIP linear model, confirming the origin of the observed behaviour. (author)
Goudarzi, Shervin; Amrollahi, R.; Niknam Sharak, M.
2014-06-01
In this paper the results of the numerical simulation for Amirkabir Mather-type Plasma Focus Facility (16 kV, 36μF and 115 nH) in several experiments with Argon as working gas at different working conditions (different discharge voltages and gas pressures) have been presented and compared with the experimental results. Two different models have been used for simulation: five-phase model of Lee and lumped parameter model of Gonzalez. It is seen that the results (optimum pressures and current signals) of the Lee model at different working conditions show better agreement than lumped parameter model with experimental values.
International Nuclear Information System (INIS)
Goudarzi, Shervin; Amrollahi, R; Sharak, M Niknam
2014-01-01
In this paper the results of the numerical simulation for Amirkabir Mather-type Plasma Focus Facility (16 kV, 36μF and 115 nH) in several experiments with Argon as working gas at different working conditions (different discharge voltages and gas pressures) have been presented and compared with the experimental results. Two different models have been used for simulation: five-phase model of Lee and lumped parameter model of Gonzalez. It is seen that the results (optimum pressures and current signals) of the Lee model at different working conditions show better agreement than lumped parameter model with experimental values.
Models of experimental saccular aneurysms of carotid arteries in canine
International Nuclear Information System (INIS)
Zhang Haixia; Cheng Yingsheng; Li Minghua
2006-01-01
Objective: To study the availability by making experimental saccular aneurysm models of carotid arteries in canine similar to human intracranial aneurysms. Methods: Twenty healthy canines with experimental saccular side-wall aneurysms of carotid arteries were created successfully by surgery. Results: Forty experimental saccular side-wall aneurysms of carotid arteries were created successfully with 36 aneurysms and parent arteries maintaining patency with each other and four spontaneously occluded confirmed by angiography. Model successful rate reached 90%. Conclusions: Experimental saccular side-wall aneurysms of carotid arteries in canines were one of best models created for simulating human intracranial aneurysms. (authors)
Experimental animal modelling for TB vaccine development
Directory of Open Access Journals (Sweden)
Pere-Joan Cardona
2017-03-01
Full Text Available Research for a novel vaccine to prevent tuberculosis is an urgent medical need. The current vaccine, BCG, has demonstrated a non-homogenous efficacy in humans, but still is the gold standard to be improved upon. In general, the main indicator for testing the potency of new candidates in animal models is the reduction of the bacillary load in the lungs at the acute phase of the infection. Usually, this reduction is similar to that induced by BCG, although in some cases a weak but significant improvement can be detected, but none of candidates are able to prevent establishment of infection. The main characteristics of several laboratory animals are reviewed, reflecting that none are able to simulate the whole characteristics of human tuberculosis. As, so far, no surrogate of protection has been found, it is important to test new candidates in several models in order to generate convincing evidence of efficacy that might be better than that of BCG in humans. It is also important to investigate the use of “in silico” and “ex vivo” models to better understand experimental data and also to try to replace, or at least reduce and refine experimental models in animals.
Experimental validation of a computer simulation of radiographic film
International Nuclear Information System (INIS)
Goncalves, Elicardo A. de S.; Azeredo, Raphaela; Assis, Joaquim T.; Anjos, Marcelino J. dos; Oliveira, Davi F.; Oliveira, Luis F. de
2015-01-01
In radiographic films, the behavior of characteristic curve is very important for the image quality. Digitization/visualization are always performed by light transmission and the characteristic curve is known as a behavior of optical density in function of exposure. In a first approach, in a Monte-Carlo computer simulation trying to build a Hurter-Driffield curve by a stochastic model, the results showed the same known shape, but some behaviors, like the influence of silver grain size, are not expected. A real H and D curve was build exposing films, developing and measuring the optical density. When comparing model results with a real curve, trying to fit them and estimating some parameters, a difference in high exposure region shows a divergence between the models and the experimental data. Since the optical density is a function of metallic silver generated by chemical development, direct proportion was considered, but the results suggests a limitation in this proportion. In fact, when the optical density was changed by another way to measure silver concentration, like x-ray fluorescence, the new results agree with the models. Therefore, overexposed films can contain areas with different silver concentrations but it can't be seen due to the fact that optical density measurement is limited. Mapping the silver concentration in the film area can be a solution to reveal these dark images, and x-ray fluorescence has shown to be the best way to perform this new way to digitize films. (author)
Experimental validation of a computer simulation of radiographic film
Energy Technology Data Exchange (ETDEWEB)
Goncalves, Elicardo A. de S., E-mail: elicardo.goncalves@ifrj.edu.br [Instituto Federal do Rio de Janeiro (IFRJ), Paracambi, RJ (Brazil). Laboratorio de Instrumentacao e Simulacao Computacional Cientificas Aplicadas; Azeredo, Raphaela, E-mail: raphaelaazeredo@yahoo.com.br [Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ (Brazil). Instituto de Fisica Armando Dias Tavares. Programa de Pos-Graduacao em Fisica; Assis, Joaquim T., E-mail: joaquim@iprj.uerj.br [Universidade do Estado do Rio de Janeiro (UERJ), Nova Friburgo, RJ (Brazil). Instituto Politecnico; Anjos, Marcelino J. dos; Oliveira, Davi F.; Oliveira, Luis F. de, E-mail: marcelin@uerj.br, E-mail: davi.oliveira@uerj.br, E-mail: lfolive@uerj.br [Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ (Brazil). Instituto de Fisica Armando Dias Tavares. Departamento de Fisica Aplicada e Termodinamica
2015-07-01
In radiographic films, the behavior of characteristic curve is very important for the image quality. Digitization/visualization are always performed by light transmission and the characteristic curve is known as a behavior of optical density in function of exposure. In a first approach, in a Monte-Carlo computer simulation trying to build a Hurter-Driffield curve by a stochastic model, the results showed the same known shape, but some behaviors, like the influence of silver grain size, are not expected. A real H and D curve was build exposing films, developing and measuring the optical density. When comparing model results with a real curve, trying to fit them and estimating some parameters, a difference in high exposure region shows a divergence between the models and the experimental data. Since the optical density is a function of metallic silver generated by chemical development, direct proportion was considered, but the results suggests a limitation in this proportion. In fact, when the optical density was changed by another way to measure silver concentration, like x-ray fluorescence, the new results agree with the models. Therefore, overexposed films can contain areas with different silver concentrations but it can't be seen due to the fact that optical density measurement is limited. Mapping the silver concentration in the film area can be a solution to reveal these dark images, and x-ray fluorescence has shown to be the best way to perform this new way to digitize films. (author)
Study of TXRF experimental system by Monte Carlo simulation
International Nuclear Information System (INIS)
Costa, Ana Cristina M.; Leitao, Roberta G.; Lopes, Ricardo T.; Anjos, Marcelino J.; Conti, Claudio C.
2011-01-01
The Total-Reflection X-ray Fluorescence (TXRF) technique offers unique possibilities to study the concentrations of a wide range of trace elements in various types of samples. Besides that, the TXRF technique is widely used to study the trace elements in biological, medical and environmental samples due to its multielemental character as well as simplicity of sample preparation and quantification methods used. In general the TXRF experimental setup is not simple and might require substantial experimental efforts. On the other hand, in recent years, experimental TXRF portable systems have been developed. It has motivated us to develop our own TXRF portable system. In this work we presented a first step in order to optimize a TXRF experimental setup using Monte Carlo simulation by MCNP code. The results found show that the Monte Carlo simulation method can be used to investigate the development of a TXRF experimental system before its assembly. (author)
Simulated and experimental compression of a compact toroid
Energy Technology Data Exchange (ETDEWEB)
Johnson, J N; Hwang, D Q; Horton, R D; Evans, R W; Owen, J M
2009-05-06
We present simulation results and experimental data for the compression of a compact toroid by a conducting nozzle without a center electrode. In both simulation and experiment, the flow of the plasma is greatly obstructed by even modest magnetic fields. A simple mechanism for this obstruction is suggested by our simulations. In particular, the configuration of the plasmoid's magnetic field plays a significant role in the success of the experiment. We analyze two types of plasma configurations under compression and demonstrate that the results from the simulations matches those from the experiments, and that the mechanism predicts the different behaviors observed in the two cases.
Experimental investigations and numerical simulations of methane cup-burner flame
Directory of Open Access Journals (Sweden)
Kubát P.
2013-04-01
Full Text Available Pulsation frequency of the cup-burner flame was determined by means of experimental investigations and numerical simulations. Simplified chemical kinetics was successfully implemented into a laminar fluid flow model applied to the complex burner geometry. Our methodical approach is based on the monitoring of flame emission, fast Fourier transformation and reproduction of measured spectral features by numerical simulations. Qualitative agreement between experimental and predicted oscillatory behaviour was obtained by employing a two-step methane oxidation scheme.
ECONOMIC MODELING STOCKS CONTROL SYSTEM: SIMULATION MODEL
Климак, М.С.; Войтко, С.В.
2016-01-01
Considered theoretical and applied aspects of the development of simulation models to predictthe optimal development and production systems that create tangible products andservices. It isproved that theprocessof inventory control needs of economicandmathematical modeling in viewof thecomplexity of theoretical studies. A simulation model of stocks control that allows make managementdecisions with production logistics
Progress in modeling and simulation.
Kindler, E
1998-01-01
For the modeling of systems, the computers are more and more used while the other "media" (including the human intellect) carrying the models are abandoned. For the modeling of knowledges, i.e. of more or less general concepts (possibly used to model systems composed of instances of such concepts), the object-oriented programming is nowadays widely used. For the modeling of processes existing and developing in the time, computer simulation is used, the results of which are often presented by means of animation (graphical pictures moving and changing in time). Unfortunately, the object-oriented programming tools are commonly not designed to be of a great use for simulation while the programming tools for simulation do not enable their users to apply the advantages of the object-oriented programming. Nevertheless, there are exclusions enabling to use general concepts represented at a computer, for constructing simulation models and for their easy modification. They are described in the present paper, together with true definitions of modeling, simulation and object-oriented programming (including cases that do not satisfy the definitions but are dangerous to introduce misunderstanding), an outline of their applications and of their further development. In relation to the fact that computing systems are being introduced to be control components into a large spectrum of (technological, social and biological) systems, the attention is oriented to models of systems containing modeling components.
Stochastic modeling analysis and simulation
Nelson, Barry L
1995-01-01
A coherent introduction to the techniques for modeling dynamic stochastic systems, this volume also offers a guide to the mathematical, numerical, and simulation tools of systems analysis. Suitable for advanced undergraduates and graduate-level industrial engineers and management science majors, it proposes modeling systems in terms of their simulation, regardless of whether simulation is employed for analysis. Beginning with a view of the conditions that permit a mathematical-numerical analysis, the text explores Poisson and renewal processes, Markov chains in discrete and continuous time, se
Mathematical model and simulations of radiation fluxes from buried radionuclides
International Nuclear Information System (INIS)
Ahmad Saat
1999-01-01
A mathematical model and a simple Monte Carlo simulations were developed to predict radiation fluxes from buried radionuclides. The model and simulations were applied to measured (experimental) data. The results of the mathematical model showed good acceptable order of magnitude agreement. A good agreement was also obtained between the simple simulations and the experimental results. Thus, knowing the radionuclide distribution profiles in soil from a core sample, it can be applied to the model or simulations to estimate the radiation fluxes emerging from the soil surface. (author)
FASTBUS simulation models in VHDL
International Nuclear Information System (INIS)
Appelquist, G.
1992-11-01
Four hardware simulation models implementing the FASTBUS protocol are described. The models are written in the VHDL hardware description language to obtain portability, i.e. without relations to any specific simulator. They include two complete FASTBUS devices, a full-duplex segment interconnect and ancillary logic for the segment. In addition, master and slave models using a high level interface to describe FASTBUS operations, are presented. With these models different configurations of FASTBUS systems can be evaluated and the FASTBUS transactions of new devices can be verified. (au)
Model reduction for circuit simulation
Hinze, Michael; Maten, E Jan W Ter
2011-01-01
Simulation based on mathematical models plays a major role in computer aided design of integrated circuits (ICs). Decreasing structure sizes, increasing packing densities and driving frequencies require the use of refined mathematical models, and to take into account secondary, parasitic effects. This leads to very high dimensional problems which nowadays require simulation times too large for the short time-to-market demands in industry. Modern Model Order Reduction (MOR) techniques present a way out of this dilemma in providing surrogate models which keep the main characteristics of the devi
Bot, G.P.A.
1989-01-01
A model is a representation of a real system to describe some properties i.e. internal factors of that system (out-puts) as function of some external factors (inputs). It is impossible to describe the relation between all internal factors (if even all internal factors could be defined) and all
Experimental study and modelling of transient boiling
International Nuclear Information System (INIS)
Baudin, Nicolas
2015-01-01
A failure in the control system of the power of a nuclear reactor can lead to a Reactivity Initiated Accident in a nuclear power plant. Then, a power peak occurs in some fuel rods, high enough to lead to the coolant film boiling. It leads to an important increase of the temperature of the rod. The possible risk of the clad failure is a matter of interest for the Institut de Radioprotection et de Securite Nucleaire. The transient boiling heat transfer is not yet understood and modelled. An experimental set-up has been built at the Institut de Mecanique des Fluides de Toulouse (IMFT). Subcooled HFE-7000 flows vertically upward in a semi annulus test section. The inner half cylinder simulates the clad and is made of a stainless steel foil, heated by Joule effect. Its temperature is measured by an infrared camera, coupled with a high speed camera for the visualization of the flow topology. The whole boiling curve is studied in steady state and transient regimes: convection, onset of boiling, nucleate boiling, critical heat flux, film boiling and rewetting. The steady state heat transfers are well modelled by literature correlations. Models are suggested for the transient heat flux: the convection and nucleate boiling evolutions are self-similar during a power step. This observation allows to model more complex evolutions, as temperature ramps. The transient Hsu model well represents the onset of nucleate boiling. When the intensity of the power step increases, the film boiling begins at the same temperature but with an increasing heat flux. For power ramps, the critical heat flux decreases while the corresponding temperature increases with the heating rate. When the wall is heated, the film boiling heat transfer is higher than in steady state but it is not understood. A two-fluid model well simulates the cooling film boiling and the rewetting. (author)
A VRLA battery simulation model
International Nuclear Information System (INIS)
Pascoe, Phillip E.; Anbuky, Adnan H.
2004-01-01
A valve regulated lead acid (VRLA) battery simulation model is an invaluable tool for the standby power system engineer. The obvious use for such a model is to allow the assessment of battery performance. This may involve determining the influence of cells suffering from state of health (SOH) degradation on the performance of the entire string, or the running of test scenarios to ascertain the most suitable battery size for the application. In addition, it enables the engineer to assess the performance of the overall power system. This includes, for example, running test scenarios to determine the benefits of various load shedding schemes. It also allows the assessment of other power system components, either for determining their requirements and/or vulnerabilities. Finally, a VRLA battery simulation model is vital as a stand alone tool for educational purposes. Despite the fundamentals of the VRLA battery having been established for over 100 years, its operating behaviour is often poorly understood. An accurate simulation model enables the engineer to gain a better understanding of VRLA battery behaviour. A system level multipurpose VRLA battery simulation model is presented. It allows an arbitrary battery (capacity, SOH, number of cells and number of strings) to be simulated under arbitrary operating conditions (discharge rate, ambient temperature, end voltage, charge rate and initial state of charge). The model accurately reflects the VRLA battery discharge and recharge behaviour. This includes the complex start of discharge region known as the coup de fouet
Sensitivity Analysis of Simulation Models
Kleijnen, J.P.C.
2009-01-01
This contribution presents an overview of sensitivity analysis of simulation models, including the estimation of gradients. It covers classic designs and their corresponding (meta)models; namely, resolution-III designs including fractional-factorial two-level designs for first-order polynomial
Computer Based Modelling and Simulation
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 3. Computer Based Modelling and Simulation - Modelling Deterministic Systems. N K Srinivasan. General Article Volume 6 Issue 3 March 2001 pp 46-54. Fulltext. Click here to view fulltext PDF. Permanent link:
Simulation and experimental research on line throwing rocket with flight
Wen-bin Gu; Ming Lu; Jian-qing Liu; Qin-xing Dong; Zhen-xiong Wang; Jiang-hai Chen
2014-01-01
The finite segment method is used to model the line throwing rocket system. A dynamic model of line throwing rocket with flight motion based on Kane's method is presented by the kinematics description of the system and the consideration of the forces acting on the system. The experiment designed according to the parameters of the dynamic model is made. The simulation and experiment results, such as range, velocity and flight time, are compared and analyzed. The simulation results are basicall...
Ye, Yan; Lv, Qingsong; Wu, Maocheng; Xu, Yishen; Gu, Jihua
2017-08-01
In view of some problems about the traditional photoelectric specialty experimental teaching process, such as separation of theoretical teaching and practical teaching, immobilization of experimental teaching contents, low quality of experiments and no obvious effect, we explored and practiced a new experimental teaching model of "theoretical teaching, virtual simulation and physical experiment", which combined the characteristics of photoelectric information science and engineering major and the essential requirements of engineering innovation talents cultivation. The virtual simulation experiment platform has many advantages, such as high performance-to-price ratio, easy operation and open experimental process, which makes virtual simulation combine physical experiment, complete each other with virtual for practical. After the users log into the virtual simulation experimental platform, they will first study the contents of the experiment, clarify the purpose and requirements of the experiment, master the method of using the instrument and the relevant notes, and then use the experimental instruments provided by the platform to build the corresponding experimental system. Once the experimenter's optical path is set incorrectly or the instrument parameters are set incorrectly, the error or warning message will be automatically triggered, and the reference information will be given instructing the student to complete the correct experimental operation. The results of our practice in recent years show that the teaching reform of the photoelectric specialty experiments has not only brought great convenience to the experimental teaching management, broadened the students' thinking and vision, enhanced the students' experimental skills and comprehensive qualities, but also made the students participate in the experiment with their enthusiasm. During the construction of experiment programs, the students' engineering practical ability and independent innovation awareness
Vehicle dynamics modeling and simulation
Schramm, Dieter; Bardini, Roberto
2014-01-01
The authors examine in detail the fundamentals and mathematical descriptions of the dynamics of automobiles. In this context different levels of complexity will be presented, starting with basic single-track models up to complex three-dimensional multi-body models. A particular focus is on the process of establishing mathematical models on the basis of real cars and the validation of simulation results. The methods presented are explained in detail by means of selected application scenarios.
MATLAB simulation for an experimental setup of digital feedback control
International Nuclear Information System (INIS)
Zheng Lifang; Liu Songqiang
2005-01-01
This paper describes the digital feedback simulation using MATLAB for an experimental accelerator control setup. By analyzing the plant characteristic in time-domain and frequency-domain, a guideline for design of digital filter and PID controller is derived. (authors)
Theory, simulation, and experimental studies of zonal flows
International Nuclear Information System (INIS)
Hahm, T. S.; Burrell, K.H.; Lin, Z.; Nazikian, R.; Synakowski, E.J.
2000-01-01
The authors report on current theoretical understanding of the characteristics of self-generated zonal flows as observed in nonlinear gyrokinetic simulations of toroidal ITG turbulence [Science 281, 1835 (1998)], and discuss various possibilities for experimental measurements of signature of zonal flows
Numerical simulation of Higgs models
International Nuclear Information System (INIS)
Jaster, A.
1995-10-01
The SU(2) Higgs and the Schwinger model on the lattice were analysed. Numerical simulations of the SU(2) Higgs model were performed to study the finite temperature electroweak phase transition. With the help of the multicanonical method the distribution of an order parameter at the phase transition point was measured. This was used to obtain the order of the phase transition and the value of the interface tension with the histogram method. Numerical simulations were also performed at zero temperature to perform renormalization. The measured values for the Wilson loops were used to determine the static potential and from this the renormalized gauge coupling. The Schwinger model was simulated at different gauge couplings to analyse the properties of the Kaplan-Shamir fermions. The prediction that the mass parameter gets only multiplicative renormalization was tested and verified. (orig.)
Stochastic models: theory and simulation.
Energy Technology Data Exchange (ETDEWEB)
Field, Richard V., Jr.
2008-03-01
Many problems in applied science and engineering involve physical phenomena that behave randomly in time and/or space. Examples are diverse and include turbulent flow over an aircraft wing, Earth climatology, material microstructure, and the financial markets. Mathematical models for these random phenomena are referred to as stochastic processes and/or random fields, and Monte Carlo simulation is the only general-purpose tool for solving problems of this type. The use of Monte Carlo simulation requires methods and algorithms to generate samples of the appropriate stochastic model; these samples then become inputs and/or boundary conditions to established deterministic simulation codes. While numerous algorithms and tools currently exist to generate samples of simple random variables and vectors, no cohesive simulation tool yet exists for generating samples of stochastic processes and/or random fields. There are two objectives of this report. First, we provide some theoretical background on stochastic processes and random fields that can be used to model phenomena that are random in space and/or time. Second, we provide simple algorithms that can be used to generate independent samples of general stochastic models. The theory and simulation of random variables and vectors is also reviewed for completeness.
Self-Radiolysis of Tritiated Water: Experimental Study and Simulation
International Nuclear Information System (INIS)
Heinze, Sylver; Stolz, Thibaut; Ducret, Didier; Colson, Jean-Claude
2005-01-01
Radioactive decay of tritium contained in tritiated water leads to the production of gaseous helium and, through self-radiolysis, to the formation of molecular hydrogen and oxygen. For safety management of tritiated water storage, it is essential to be able to predict pressure increase resulting from this phenomenon. The present study aims to identify the mechanisms that take place in self-radiolysis of chemically pure liquid tritiated water. The evolution of the concentration of hydrogen and oxygen in the gas phase of closed vessels containing tritiated water has been followed experimentally. Simulation of pure water radiolysis has been carried out using data from the literature. In order to fit experimental results, simulation should take into account gas phase recombination reaction between hydrogen and oxygen. A simplified system has been extracted from the complete chemical system used to simulate radiolysis. This system allows identifying the basic mechanisms that are responsible for tritiated water self-radiolysis
Plasma modelling and numerical simulation
International Nuclear Information System (INIS)
Van Dijk, J; Kroesen, G M W; Bogaerts, A
2009-01-01
Plasma modelling is an exciting subject in which virtually all physical disciplines are represented. Plasma models combine the electromagnetic, statistical and fluid dynamical theories that have their roots in the 19th century with the modern insights concerning the structure of matter that were developed throughout the 20th century. The present cluster issue consists of 20 invited contributions, which are representative of the state of the art in plasma modelling and numerical simulation. These contributions provide an in-depth discussion of the major theories and modelling and simulation strategies, and their applications to contemporary plasma-based technologies. In this editorial review, we introduce and complement those papers by providing a bird's eye perspective on plasma modelling and discussing the historical context in which it has surfaced. (editorial review)
EXPERIMENTAL MEASUREMENT, ANALYSIS AND MODELLING ...
African Journals Online (AJOL)
30 juin 2010 ... We obtain a good agreement between the resolution of the nonlinear equation of heat and the results obtained by the experimentation. . Keywords: Emissivity, Température, optimal Linearisation, finite elements. 1. ..... basse température, Rapport de Stage de D.E.A, Université Paris 12 – Val de Marne.
Experimental Oral Candidiasis in Animal Models
Samaranayake, Yuthika H.; Samaranayake, Lakshman P.
2001-01-01
Oral candidiasis is as much the final outcome of the vulnerability of the host as of the virulence of the invading organism. We review here the extensive literature on animal experiments mainly appertaining to the host predisposing factors that initiate and perpetuate these infections. The monkey, rat, and mouse are the choice models for investigating oral candidiasis, but comparisons between the same or different models appear difficult, because of variables such as the study design, the number of animals used, their diet, the differences in Candida strains, and the duration of the studies. These variables notwithstanding, the following could be concluded. (i) The primate model is ideal for investigating Candida-associated denture stomatitis since both erythematous and pseudomembranous lesions have been produced in monkeys with prosthetic plates; they are, however, expensive and difficult to obtain and maintain. (ii) The rat model (both Sprague-Dawley and Wistar) is well proven for observing chronic oral candidal colonization and infection, due to the ease of breeding and handling and their ready availability. (iii) Mice are similar, but in addition there are well characterized variants simulating immunologic and genetic abnormalities (e.g., athymic, euthymic, murine-acquired immune deficiency syndrome, and severe combined immunodeficient models) and hence are used for short-term studies relating the host immune response and oral candidiasis. Nonetheless, an ideal, relatively inexpensive model representative of the human oral environment in ecological and microbiological terms is yet to be described. Until such a model is developed, researchers should pay attention to standardization of the experimental protocols described here to obtain broadly comparable and meaningful data. PMID:11292645
Experimental models for Murray’s law
Akita, Dai; Kunita, Itsuki; Fricker, Mark D.; Kuroda, Shigeru; Sato, Katsuhiko; Nakagaki, Toshiyuki
2017-01-01
Transport networks are ubiquitous in multicellular organisms and include leaf veins, fungal mycelia and blood vessels. While transport of materials and signals through the network plays a crucial role in maintaining the living system, the transport capacity of the network can best be understood in terms of hydrodynamics. We report here that plasmodium from the large, single-celled amoeboid Physarum was able to construct a hydrodynamically optimized vein-network when evacuating biomass from confined arenas of various shapes through a narrow exit. Increasingly thick veins developed towards the exit, and the network spanned the arena via repetitive bifurcations to give a branching tree. The Hausdorff distance from all parts of the plasmodium to the vein network was kept low, whilst the hydrodynamic conductivity from distal parts of the network to the exit was equivalent, irrespective of the arena shape. This combination of spatial patterning and differential vein thickening served to evacuate biomass at an equivalent rate across the entire arena. The scaling relationship at the vein branches was determined experimentally to be 2.53-3.29, consistent with predictions from Murray’s law. Furthermore, we show that mathematical models for self-organised, adaptive transport in Physarum simulate the experimental network organisation well if the scaling coefficient of the current-reinforcement rule is set to 3. In simulations, this resulted in rapid development of an optimal network that minimised the combined volume and frictional energy in comparison with other scaling coefficients. This would predict that the boundary shear forces within each vein are constant throughout the network, and would be consistent with a feedback mechanism based on a sensing a threshold shear at the vein wall.
Experimental models for Murray’s law
International Nuclear Information System (INIS)
Akita, Dai; Kunita, Itsuki; Fricker, Mark D; Kuroda, Shigeru; Sato, Katsuhiko; Nakagaki, Toshiyuki
2017-01-01
Transport networks are ubiquitous in multicellular organisms and include leaf veins, fungal mycelia and blood vessels. While transport of materials and signals through the network plays a crucial role in maintaining the living system, the transport capacity of the network can best be understood in terms of hydrodynamics. We report here that plasmodium from the large, single-celled amoeboid Physarum was able to construct a hydrodynamically optimized vein-network when evacuating biomass from confined arenas of various shapes through a narrow exit. Increasingly thick veins developed towards the exit, and the network spanned the arena via repetitive bifurcations to give a branching tree. The Hausdorff distance from all parts of the plasmodium to the vein network was kept low, whilst the hydrodynamic conductivity from distal parts of the network to the exit was equivalent, irrespective of the arena shape. This combination of spatial patterning and differential vein thickening served to evacuate biomass at an equivalent rate across the entire arena. The scaling relationship at the vein branches was determined experimentally to be 2.53–3.29, consistent with predictions from Murray’s law. Furthermore, we show that mathematical models for self-organised, adaptive transport in Physarum simulate the experimental network organisation well if the scaling coefficient of the current-reinforcement rule is set to 3. In simulations, this resulted in rapid development of an optimal network that minimised the combined volume and frictional energy in comparison with other scaling coefficients. This would predict that the boundary shear forces within each vein are constant throughout the network, and would be consistent with a feedback mechanism based on a sensing a threshold shear at the vein wall. (paper)
Tsunamigenic earthquake simulations using experimentally derived friction laws
Murphy, S.; Di Toro, G.; Romano, F.; Scala, A.; Lorito, S.; Spagnuolo, E.; Aretusini, S.; Festa, G.; Piatanesi, A.; Nielsen, S.
2018-03-01
Seismological, tsunami and geodetic observations have shown that subduction zones are complex systems where the properties of earthquake rupture vary with depth as a result of different pre-stress and frictional conditions. A wealth of earthquakes of different sizes and different source features (e.g. rupture duration) can be generated in subduction zones, including tsunami earthquakes, some of which can produce extreme tsunamigenic events. Here, we offer a geological perspective principally accounting for depth-dependent frictional conditions, while adopting a simplified distribution of on-fault tectonic pre-stress. We combine a lithology-controlled, depth-dependent experimental friction law with 2D elastodynamic rupture simulations for a Tohoku-like subduction zone cross-section. Subduction zone fault rocks are dominantly incohesive and clay-rich near the surface, transitioning to cohesive and more crystalline at depth. By randomly shifting along fault dip the location of the high shear stress regions ("asperities"), moderate to great thrust earthquakes and tsunami earthquakes are produced that are quite consistent with seismological, geodetic, and tsunami observations. As an effect of depth-dependent friction in our model, slip is confined to the high stress asperity at depth; near the surface rupture is impeded by the rock-clay transition constraining slip to the clay-rich layer. However, when the high stress asperity is located in the clay-to-crystalline rock transition, great thrust earthquakes can be generated similar to the Mw 9 Tohoku (2011) earthquake.
2015-03-26
response. Additionally, choosing correlated levels for multiple factors results in multicollinearity which can cause problems such as model...misspecification or large variances and covariances for the regression coefficients. A good way to avoid multicollinearity is to use orthogonal, factorial
Model for Simulation Atmospheric Turbulence
DEFF Research Database (Denmark)
Lundtang Petersen, Erik
1976-01-01
A method that produces realistic simulations of atmospheric turbulence is developed and analyzed. The procedure makes use of a generalized spectral analysis, often called a proper orthogonal decomposition or the Karhunen-Loève expansion. A set of criteria, emphasizing a realistic appearance...... eigenfunctions and estimates of the distributions of the corresponding expansion coefficients. The simulation method utilizes the eigenfunction expansion procedure to produce preliminary time histories of the three velocity components simultaneously. As a final step, a spectral shaping procedure is then applied....... The method is unique in modeling the three velocity components simultaneously, and it is found that important cross-statistical features are reasonably well-behaved. It is concluded that the model provides a practical, operational simulator of atmospheric turbulence....
International Nuclear Information System (INIS)
Robert, Y.
2007-09-01
This work is a part of study which goal is to realize a computer modelling of the thermomechanical phenomena occurring during the YAG pulse laser welding of titanium alloy (TA6V). The filet welding has different heterogeneities (microstructural and mechanical). In fact, the temperature causes microstructural changes (phase transformations, precipitations) and modifies the mechanical properties. Thermomechanical modelling has thus to be established for the welding of TA6V. (author)
Directory of Open Access Journals (Sweden)
Deirdre R. Meldrum
2012-06-01
Full Text Available Single-cell studies of phenotypic heterogeneity reveal more information about pathogenic processes than conventional bulk-cell analysis methods. By enabling high-resolution structural and functional imaging, a single-cell three-dimensional (3D imaging system can be used to study basic biological processes and to diagnose diseases such as cancer at an early stage. One mechanism that such systems apply to accomplish 3D imaging is rotation of a single cell about a fixed axis. However, many cell rotation mechanisms require intricate and tedious microfabrication, or fail to provide a suitable environment for living cells. To address these and related challenges, we applied numerical simulation methods to design new microfluidic chambers capable of generating fluidic microvortices to rotate suspended cells. We then compared several microfluidic chip designs experimentally in terms of: (1 their ability to rotate biological cells in a stable and precise manner; and (2 their suitability, from a geometric standpoint, for microscopic cell imaging. We selected a design that incorporates a trapezoidal side chamber connected to a main flow channel because it provided well-controlled circulation and met imaging requirements. Micro particle-image velocimetry (micro-PIV was used to provide a detailed characterization of flows in the new design. Simulated and experimental results demonstrate that a trapezoidal side chamber represents a viable option for accomplishing controlled single cell rotation. Further, agreement between experimental and simulated results confirms that numerical simulation is an effective method for chamber design.
IVIM: modeling, experimental validation and application to animal models
International Nuclear Information System (INIS)
Fournet, Gabrielle
2016-01-01
This PhD thesis is centered on the study of the IVIM ('Intravoxel Incoherent Motion') MRI sequence. This sequence allows for the study of the blood microvasculature such as the capillaries, arterioles and venules. To be sensitive only to moving groups of spins, diffusion gradients are added before and after the 180 degrees pulse of a spin echo (SE) sequence. The signal component corresponding to spins diffusing in the tissue can be separated from the one related to spins travelling in the blood vessels which is called the IVIM signal. These two components are weighted by f IVIM which represents the volume fraction of blood inside the tissue. The IVIM signal is usually modelled by a mono-exponential (ME) function and characterized by a pseudo-diffusion coefficient, D*. We propose instead a bi-exponential IVIM model consisting of a slow pool, characterized by F slow and D* slow corresponding to the capillaries as in the ME model, and a fast pool, characterized by F fast and D* fast, related to larger vessels such as medium-size arterioles and venules. This model was validated experimentally and more information was retrieved by comparing the experimental signals to a dictionary of simulated IVIM signals. The influence of the pulse sequence, the repetition time and the diffusion encoding time was also studied. Finally, the IVIM sequence was applied to the study of an animal model of Alzheimer's disease. (author) [fr
Modeling, simulation and optimization of bipedal walking
Berns, Karsten
2013-01-01
The model-based investigation of motions of anthropomorphic systems is an important interdisciplinary research topic involving specialists from many fields such as Robotics, Biomechanics, Physiology, Orthopedics, Psychology, Neurosciences, Sports, Computer Graphics and Applied Mathematics. This book presents a study of basic locomotion forms such as walking and running is of particular interest due to the high demand on dynamic coordination, actuator efficiency and balance control. Mathematical models and numerical simulation and optimization techniques are explained, in combination with experimental data, which can help to better understand the basic underlying mechanisms of these motions and to improve them. Example topics treated in this book are Modeling techniques for anthropomorphic bipedal walking systems Optimized walking motions for different objective functions Identification of objective functions from measurements Simulation and optimization approaches for humanoid robots Biologically inspired con...
Platform for Modeling and Simulation of Photovoltaic Generation Systems
Directory of Open Access Journals (Sweden)
Anny A. Arroyave-Berrio
2013-11-01
Full Text Available A platform for modeling and simulation using Matlab is presented. The platform has four models of photovoltaic panels. It identifies the parameters of each one, for a given solar panel, based on experimental data of voltage, current and environmental conditions. Also the platform generates four blocks, for using in Matlab-Simulink and Psim simulation tools. The experimental validation of the platform was made using the PV panels of the Metropolitan Technological Institute (ITM Lab.
Radiation Modeling with Direct Simulation Monte Carlo
Carlson, Ann B.; Hassan, H. A.
1991-01-01
Improvements in the modeling of radiation in low density shock waves with direct simulation Monte Carlo (DSMC) are the subject of this study. A new scheme to determine the relaxation collision numbers for excitation of electronic states is proposed. This scheme attempts to move the DSMC programs toward a more detailed modeling of the physics and more reliance on available rate data. The new method is compared with the current modeling technique and both techniques are compared with available experimental data. The differences in the results are evaluated. The test case is based on experimental measurements from the AVCO-Everett Research Laboratory electric arc-driven shock tube of a normal shock wave in air at 10 km/s and .1 Torr. The new method agrees with the available data as well as the results from the earlier scheme and is more easily extrapolated to di erent ow conditions.
Simulation of FRET dyes allows quantitative comparison against experimental data
Reinartz, Ines; Sinner, Claude; Nettels, Daniel; Stucki-Buchli, Brigitte; Stockmar, Florian; Panek, Pawel T.; Jacob, Christoph R.; Nienhaus, Gerd Ulrich; Schuler, Benjamin; Schug, Alexander
2018-03-01
Fully understanding biomolecular function requires detailed insight into the systems' structural dynamics. Powerful experimental techniques such as single molecule Förster Resonance Energy Transfer (FRET) provide access to such dynamic information yet have to be carefully interpreted. Molecular simulations can complement these experiments but typically face limits in accessing slow time scales and large or unstructured systems. Here, we introduce a coarse-grained simulation technique that tackles these challenges. While requiring only few parameters, we maintain full protein flexibility and include all heavy atoms of proteins, linkers, and dyes. We are able to sufficiently reduce computational demands to simulate large or heterogeneous structural dynamics and ensembles on slow time scales found in, e.g., protein folding. The simulations allow for calculating FRET efficiencies which quantitatively agree with experimentally determined values. By providing atomically resolved trajectories, this work supports the planning and microscopic interpretation of experiments. Overall, these results highlight how simulations and experiments can complement each other leading to new insights into biomolecular dynamics and function.
DEFF Research Database (Denmark)
Nauheimer, Michael; Relan, Rishi; Madsen, Henrik
2017-01-01
composites, without the possibility of visual inspection of the infusion process calls for a sensor system (possibly virtual) for monitoring the process. This paper proposes a two-step modelling methodology to identify the parameters related to the flow-front that are essential for determining the current...
Nonlinear friction model for servo press simulation
Ma, Ninshu; Sugitomo, Nobuhiko; Kyuno, Takunori; Tamura, Shintaro; Naka, Tetsuo
2013-12-01
The friction coefficient was measured under an idealized condition for a pulse servo motion. The measured friction coefficient and its changing with both sliding distance and a pulse motion showed that the friction resistance can be reduced due to the re-lubrication during unloading process of the pulse servo motion. Based on the measured friction coefficient and its changes with sliding distance and re-lubrication of oil, a nonlinear friction model was developed. Using the newly developed the nonlinear friction model, a deep draw simulation was performed and the formability was evaluated. The results were compared with experimental ones and the effectiveness was verified.
Directory of Open Access Journals (Sweden)
Naíme de Barcellos Trevisan
2009-02-01
Full Text Available Este trabalho tem como objetivo verificar a confiabilidade do Modelo Pampa Corte na predição de desempenho de bovinos de corte, em sistemas de pastejo. Para tanto, foram confrontados os valores preditos pelo modelo com dados disponíveis na literatura. Foram verificados coeficientes de correlação acima de 90% entre os dados reais e os simulados em todas as alternativas testadas. O banco de dados do Modelo precisa ser ampliado em termos de alternativas de produtividade das forrageiras, em diferentes condições climáticas. Os parâmetros qualitativos degradabilidade da proteína bruta e fibra em detergente neutro da consorciação aveia preta e azevém necessitam ainda ser pesquisados, assim como o desempenho de animais em pastagens singulares de aveia ou azevém.This study had the objective to evaluate Pampa Corte Model’s reliability in predicting beef cattle performance in grazing systems. For this purpose, model’s predicted values were compared to available data base of published papers. Correlation coefficients above 90 % were obtained between simulated and real data in all tested alternatives. Model’s data base should be enlarged by forage productivity data in different climatic conditions. Mixtures of Italian ryegrass and oat need more studies to obtain qualitative parameters (crude protein degradability and neutral detergent fiber, as well, animal performance in the single pastures of oat or Italian ryegrass.
Computer simulations and the changing face of scientific experimentation
Duran, Juan M
2013-01-01
Computer simulations have become a central tool for scientific practice. Their use has replaced, in many cases, standard experimental procedures. This goes without mentioning cases where the target system is empirical but there are no techniques for direct manipulation of the system, such as astronomical observation. To these cases, computer simulations have proved to be of central importance. The question about their use and implementation, therefore, is not only a technical one but represents a challenge for the humanities as well. In this volume, scientists, historians, and philosophers joi
Experimental Evaluation of Simulation Abstractions for Wireless Sensor Network MAC Protocols
Directory of Open Access Journals (Sweden)
G. P. Halkes
2010-01-01
Full Text Available The evaluation of MAC protocols for Wireless Sensor Networks (WSNs is often performed through simulation. These simulations necessarily abstract away from reality in many ways. However, the impact of these abstractions on the results of the simulations has received only limited attention. Moreover, many studies on the accuracy of simulation have studied either the physical layer and per link effects or routing protocol effects. To the best of our knowledge, no other work has focused on the study of the simulation abstractions with respect to MAC protocol performance. In this paper, we present the results of an experimental study of two often used abstractions in the simulation of WSN MAC protocols. We show that a simple SNR-based reception model can provide quite accurate results for metrics commonly used to evaluate MAC protocols. Furthermore, we provide an analysis of what the main sources of deviation are and thereby how the simulations can be improved to provide even better results.
Modeling and Simulation for Safeguards
International Nuclear Information System (INIS)
Swinhoe, Martyn T.
2012-01-01
The purpose of this talk is to give an overview of the role of modeling and simulation in Safeguards R and D and introduce you to (some of) the tools used. Some definitions are: (1) Modeling - the representation, often mathematical, of a process, concept, or operation of a system, often implemented by a computer program; (2) Simulation - the representation of the behavior or characteristics of one system through the use of another system, especially a computer program designed for the purpose; and (3) Safeguards - the timely detection of diversion of significant quantities of nuclear material. The role of modeling and simulation are: (1) Calculate amounts of material (plant modeling); (2) Calculate signatures of nuclear material etc. (source terms); and (3) Detector performance (radiation transport and detection). Plant modeling software (e.g. FACSIM) gives the flows and amount of material stored at all parts of the process. In safeguards this allow us to calculate the expected uncertainty of the mass and evaluate the expected MUF. We can determine the measurement accuracy required to achieve a certain performance.
Experimental and Kinetic Modeling Study of Ethyl Levulinate Oxidation in a Jet-Stirred Reactor
Wang, Jui-Yang
2017-01-01
levulinate chemical kinetic model was first developed by Dr. Stephen Dooley, Trinity College Dublin, and simulated under the same conditions, using the Perfect-Stirred Reactor code in Chemkin software. In comparing the simulation results with experimental
Novel sensors for food inspection modelling, fabrication and experimentation
Abdul Rahman, Mohd Syaifudin; Yu, Pak-Lam
2014-01-01
This book addresses presents recent developments of novel planar interdigital sensors for food inspection. It covers the fundamentals of sensors, their design, modelling and simulations, fabrications, characterizations, experimental investigations and analyses. This book will be useful for the engineers and researchers especially higher undergraduate, postgraduate students as well as practitioners working on the development of Electromagnetic Sensors.
Knoch, Fabian; Schäfer, Ken; Diezemann, Gregor; Speck, Thomas
2018-01-01
We present a dynamic coarse-graining technique that allows one to simulate the mechanical unfolding of biomolecules or molecular complexes on experimentally relevant time scales. It is based on Markov state models (MSMs), which we construct from molecular dynamics simulations using the pulling coordinate as an order parameter. We obtain a sequence of MSMs as a function of the discretized pulling coordinate, and the pulling process is modeled by switching among the MSMs according to the protocol applied to unfold the complex. This way we cover seven orders of magnitude in pulling speed. In the region of rapid pulling, we additionally perform steered molecular dynamics simulations and find excellent agreement between the results of the fully atomistic and the dynamically coarse-grained simulations. Our technique allows the determination of the rates of mechanical unfolding in a dynamical range from approximately 10-8/ns to 1/ns thus reaching experimentally accessible time regimes without abandoning atomistic resolution.
Assessment of Molecular Modeling & Simulation
Energy Technology Data Exchange (ETDEWEB)
None
2002-01-03
This report reviews the development and applications of molecular and materials modeling in Europe and Japan in comparison to those in the United States. Topics covered include computational quantum chemistry, molecular simulations by molecular dynamics and Monte Carlo methods, mesoscale modeling of material domains, molecular-structure/macroscale property correlations like QSARs and QSPRs, and related information technologies like informatics and special-purpose molecular-modeling computers. The panel's findings include the following: The United States leads this field in many scientific areas. However, Canada has particular strengths in DFT methods and homogeneous catalysis; Europe in heterogeneous catalysis, mesoscale, and materials modeling; and Japan in materials modeling and special-purpose computing. Major government-industry initiatives are underway in Europe and Japan, notably in multi-scale materials modeling and in development of chemistry-capable ab-initio molecular dynamics codes.
Seasonal cycle of Martian climate : Experimental data and numerical simulation
Rodin, A. V.; Willson, R. J.
2006-01-01
The most adequate theoretical method of investigating the present-day Martian climate is numerical simulation based on a model of general circulation of the atmosphere. First and foremost, such models encounter the greatest difficulties in description of aerosols and clouds, which in turn
International Nuclear Information System (INIS)
Kluson, J.; Jansky, B.
2009-01-01
Reference mixed neutron-gamma fields are used for test and calibration of dosimetric and spectrometric systems, intercomparison measurements, and benchmark tests and represent experimental base for reactor studies. Set of the spherical experimental assemblies for the mixed neutron-gamma reference fields implementation was build in the NRI Rez. Extended sets of measurements and simulation calculations were done to describe the reference mixed field dosimetry and spectral characteristics with best achievable precision. The Monte Carlo technique was used for different experimental setups models description, comparison and verification and field characteristics simulation. Effects (hardly distinguishable experimentally) were also studied ( contributions from individual parts of experimental setup, field individual components and next effects as shadow shield cones transparency, etc.). Some results and main conclusions of these studies and calculations are presented and discussed. (authors)
International Nuclear Information System (INIS)
Kluson, J.; Jansky, B.
2008-01-01
Reference mixed neutron-gamma fields are used for test and calibration of dosimetric and spectrometric systems, intercomparison measurements, and benchmark tests and represent experimental base for reactor studies. Set of the spherical experimental assemblies for the mixed neutron-gamma reference fields implementation was build in the NRI Rez. Extended sets of measurements and simulation calculations were done to describe the reference mixed field dosimetry and spectral characteristics with best achievable precision. The Monte Carlo technique was used for different experimental setups models description, comparison and verification and field characteristics simulation. Effects (hardly distinguishable experimentally) were also studied ( contributions from individual parts of experimental setup, field individual components and next effects as shadow shield cones transparency, etc.). Some results and main conclusions of these studies and calculations are presented and discussed. (authors)
NRTA simulation by modeling PFPF
International Nuclear Information System (INIS)
Asano, Takashi; Fujiwara, Shigeo; Takahashi, Saburo; Shibata, Junichi; Totsu, Noriko
2003-01-01
In PFPF, NRTA system has been applied since 1991. It has been confirmed by evaluating facility material accountancy data provided from operator in each IIV that a significant MUF was not generated. In case of throughput of PFPF scale, MUF can be evaluated with a sufficient detection probability by the present NRTA evaluation manner. However, by increasing of throughput, the uncertainty of material accountancy will increase, and the detection probability will decline. The relationship between increasing of throughput and declining of detection probability and the maximum throughput upon application of following measures with a sufficient detection probability were evaluated by simulation of NRTA system. This simulation was performed by modeling of PFPF. Measures for increasing detection probability are shown as follows. Shortening of the evaluation interval. Segmentation of evaluation area. This report shows the results of these simulations. (author)
Investigation of approximate models of experimental temperature characteristics of machines
Parfenov, I. V.; Polyakov, A. N.
2018-05-01
This work is devoted to the investigation of various approaches to the approximation of experimental data and the creation of simulation mathematical models of thermal processes in machines with the aim of finding ways to reduce the time of their field tests and reducing the temperature error of the treatments. The main methods of research which the authors used in this work are: the full-scale thermal testing of machines; realization of various approaches at approximation of experimental temperature characteristics of machine tools by polynomial models; analysis and evaluation of modelling results (model quality) of the temperature characteristics of machines and their derivatives up to the third order in time. As a result of the performed researches, rational methods, type, parameters and complexity of simulation mathematical models of thermal processes in machine tools are proposed.
International Nuclear Information System (INIS)
Yan Hao; Tian Zhaofei
2014-01-01
In the third loop of China Experimental Fast Reactor (CEFR), steam turboset take an important role in converting heat energy into electric energy. However, turbo sets have not been operated on the condition of more than 40%P_0 (P_0 is full power) since they were installed. Thus it is necessary to make an analogue simulation. Based on the real models of turbo sets in CEFR, simulation models were created with the help of Flowmaster platform. By using such simulation models, a steady state result in full power circumstance was got, which is in accordance with design parameters. Meanwhile, a transient state simulation with operating condition ranging from full power to 40%P_0 was accomplished and a result which verifies part of performance and running conditions of turbo sets was got. The result of analogue simulation shows that based on Flowmaster platform, the running condition of simulation models can comply with design requirement, and offer reference values to the actual running. Such simulation models can also offer reference values to other simulation models in the third loop of CEFR. (authors)
Repository simulation model: Final report
International Nuclear Information System (INIS)
1988-03-01
This report documents the application of computer simulation for the design analysis of the nuclear waste repository's waste handling and packaging operations. The Salt Repository Simulation Model was used to evaluate design alternatives during the conceptual design phase of the Salt Repository Project. Code development and verification was performed by the Office of Nuclear Waste Isolation (ONWL). The focus of this report is to relate the experience gained during the development and application of the Salt Repository Simulation Model to future repository design phases. Design of the repository's waste handling and packaging systems will require sophisticated analysis tools to evaluate complex operational and logistical design alternatives. Selection of these design alternatives in the Advanced Conceptual Design (ACD) and License Application Design (LAD) phases must be supported by analysis to demonstrate that the repository design will cost effectively meet DOE's mandated emplacement schedule and that uncertainties in the performance of the repository's systems have been objectively evaluated. Computer simulation of repository operations will provide future repository designers with data and insights that no other analytical form of analysis can provide. 6 refs., 10 figs
Simulation and experimental research on line throwing rocket with flight
Directory of Open Access Journals (Sweden)
Wen-bin Gu
2014-06-01
Full Text Available The finite segment method is used to model the line throwing rocket system. A dynamic model of line throwing rocket with flight motion based on Kane's method is presented by the kinematics description of the system and the consideration of the forces acting on the system. The experiment designed according to the parameters of the dynamic model is made. The simulation and experiment results, such as range, velocity and flight time, are compared and analyzed. The simulation results are basically agreed with the test data, which shows that the flight motion of the line throwing rocket can be predicted by the dynamic model. A theoretical model and guide for the further research on the disturbance of rope and the guidance, flight control of line throwing rocket are provided by the dynamic modeling.
Weigel, Martin
2011-09-01
Over the last couple of years it has been realized that the vast computational power of graphics processing units (GPUs) could be harvested for purposes other than the video game industry. This power, which at least nominally exceeds that of current CPUs by large factors, results from the relative simplicity of the GPU architectures as compared to CPUs, combined with a large number of parallel processing units on a single chip. To benefit from this setup for general computing purposes, the problems at hand need to be prepared in a way to profit from the inherent parallelism and hierarchical structure of memory accesses. In this contribution I discuss the performance potential for simulating spin models, such as the Ising model, on GPU as compared to conventional simulations on CPU.
Standard for Models and Simulations
Steele, Martin J.
2016-01-01
This NASA Technical Standard establishes uniform practices in modeling and simulation to ensure essential requirements are applied to the design, development, and use of models and simulations (MS), while ensuring acceptance criteria are defined by the program project and approved by the responsible Technical Authority. It also provides an approved set of requirements, recommendations, and criteria with which MS may be developed, accepted, and used in support of NASA activities. As the MS disciplines employed and application areas involved are broad, the common aspects of MS across all NASA activities are addressed. The discipline-specific details of a given MS should be obtained from relevant recommended practices. The primary purpose is to reduce the risks associated with MS-influenced decisions by ensuring the complete communication of the credibility of MS results.
Numerical model simulation of atmospheric coolant plumes
International Nuclear Information System (INIS)
Gaillard, P.
1980-01-01
The effect of humid atmospheric coolants on the atmosphere is simulated by means of a three-dimensional numerical model. The atmosphere is defined by its natural vertical profiles of horizontal velocity, temperature, pressure and relative humidity. Effluent discharge is characterised by its vertical velocity and the temperature of air satured with water vapour. The subject of investigation is the area in the vicinity of the point of discharge, with due allowance for the wake effect of the tower and buildings and, where application, wind veer with altitude. The model equations express the conservation relationships for mometum, energy, total mass and water mass, for an incompressible fluid behaving in accordance with the Boussinesq assumptions. Condensation is represented by a simple thermodynamic model, and turbulent fluxes are simulated by introduction of turbulent viscosity and diffusivity data based on in-situ and experimental water model measurements. The three-dimensional problem expressed in terms of the primitive variables (u, v, w, p) is governed by an elliptic equation system which is solved numerically by application of an explicit time-marching algorithm in order to predict the steady-flow velocity distribution, temperature, water vapour concentration and the liquid-water concentration defining the visible plume. Windstill conditions are simulated by a program processing the elliptic equations in an axisymmetrical revolution coordinate system. The calculated visible plumes are compared with plumes observed on site with a view to validate the models [fr
Große Perdekamp, Markus; Braunwarth, Roland; Kromeier, Jan; Nadjem, Hadi; Pollak, Stefan; Thierauf, Annette
2013-07-01
In current forensic practice, fatal injuries from black powder guns are rare events. In contact and close-range shots, the intensity of GSR deposition (soot, powder particles) is much greater than that in shots with smokeless powder ammunition. The same applies to any burning effects from the combustion gases. Besides, a wad of felt interposed between the propellant and the lead bullet may enter the wound channel. Apart from these findings seen in close-range shots, another characteristic feature results from the mostly spherical shape of the missiles causing maximum tissue damage at the entrance site. Two fatal injuries inflicted with muzzle-loading weapons are reported. In the first case, suicide was committed with a cal. 11.6 mm miniature cannon by firing a contact shot to the back of the neck. In test shots using black powder (1 and 2 g) as propellant, the mean bullet velocity measured 1 m away from the weapon was 87.11 and 146.85 m/s, respectively, corresponding to a kinetic energy of 32.49 and 92.95 J, respectively. Contact test shots to composite models consisting of ballistic soap covered by pig skin at the entrance site were evaluated by CT and revealed cone-like cavitations along the bullet path as known from spherical missiles and penetration depths up to 25 cm. The second case presented deals with a homicidal close-range shot discharged from a muzzle-loading percussion pistol cal. .44. The skin around the entrance site (root of the nose) was densely covered with blackish soot and powder particles, whereas the eyebrows and eyelashes showed singeing of the hairs. The flattened bullet and the wad had got stuck under the scalp of the occipital region. In both cases, there was a disproportionally large zone of tissue destruction in the initial parts of the wound tracks.
Experimental validation of neutron activation simulation of a varian medical linear accelerator.
Morato, S; Juste, B; Miro, R; Verdu, G; Diez, S
2016-08-01
This work presents a Monte Carlo simulation using the last version of MCNP, v. 6.1.1, of a Varian CLinAc emitting a 15MeV photon beam. The main objective of the work is to estimate the photoneutron production and activated products inside the medical linear accelerator head. To that, the Varian LinAc head was modelled in detail using the manufacturer information, and the model was generated with a CAD software and exported as a mesh to be included in the particle transport simulation. The model includes the transport of photoneutrons generated by primary photons and the (n, γ) reactions which can result in activation products. The validation of this study was done using experimental measures. Activation products have been identified by in situ gamma spectroscopy placed at the jaws exit of the LinAc shortly after termination of a high energy photon beam irradiation. Comparison between experimental and simulation results shows good agreement.
Advances in NLTE Modeling for Integrated Simulations
Energy Technology Data Exchange (ETDEWEB)
Scott, H A; Hansen, S B
2009-07-08
The last few years have seen significant progress in constructing the atomic models required for non-local thermodynamic equilibrium (NLTE) simulations. Along with this has come an increased understanding of the requirements for accurately modeling the ionization balance, energy content and radiative properties of different elements for a wide range of densities and temperatures. Much of this progress is the result of a series of workshops dedicated to comparing the results from different codes and computational approaches applied to a series of test problems. The results of these workshops emphasized the importance of atomic model completeness, especially in doubly excited states and autoionization transitions, to calculating ionization balance, and the importance of accurate, detailed atomic data to producing reliable spectra. We describe a simple screened-hydrogenic model that calculates NLTE ionization balance with surprising accuracy, at a low enough computational cost for routine use in radiation-hydrodynamics codes. The model incorporates term splitting, {Delta}n = 0 transitions, and approximate UTA widths for spectral calculations, with results comparable to those of much more detailed codes. Simulations done with this model have been increasingly successful at matching experimental data for laser-driven systems and hohlraums. Accurate and efficient atomic models are just one requirement for integrated NLTE simulations. Coupling the atomic kinetics to hydrodynamics and radiation transport constrains both discretizations and algorithms to retain energy conservation, accuracy and stability. In particular, the strong coupling between radiation and populations can require either very short timesteps or significantly modified radiation transport algorithms to account for NLTE material response. Considerations such as these continue to provide challenges for NLTE simulations.
Simulation test of PIUS-type reactor with large scale experimental apparatus
International Nuclear Information System (INIS)
Tamaki, M.; Tsuji, Y.; Ito, T.; Tasaka, K.; Kukita, Yutaka
1995-01-01
A large scale experimental apparatus for simulating the PIUS-type reactor has been constructed keeping the volumetric scaling ratio to the realistic reactor model. Fundamental experiments such as a steady state operation and a pump trip simulation were performed. Experimental results were compared with those obtained by the small scale apparatus in JAERI. We have already reported the effectiveness of the feedback control for the primary loop pump speed (PI control) for the stable operation. In this paper this feedback system is modified and the PID control is introduced. This new system worked well for the operation of the PIUS-type reactor even in a rapid transient condition. (author)
Developing Phenomena Models from Experimental Data
DEFF Research Database (Denmark)
Kristensen, Niels Rode; Madsen, Henrik; Jørgensen, Sten Bay
2003-01-01
A systematic approach for developing phenomena models from experimental data is presented. The approach is based on integrated application of stochastic differential equation (SDE) modelling and multivariate nonparametric regression, and it is shown how these techniques can be used to uncover...... unknown functionality behind various phenomena in first engineering principles models using experimental data. The proposed modelling approach has significant application potential, e.g. for determining unknown reaction kinetics in both chemical and biological processes. To illustrate the performance...... of the approach, a case study is presented, which shows how an appropriate phenomena model for the growth rate of biomass in a fed-batch bioreactor can be inferred from data....
Developing Phenomena Models from Experimental Data
DEFF Research Database (Denmark)
A systematic approach for developing phenomena models from experimental data is presented. The approach is based on integrated application of stochastic differential equation (SDE) modelling and multivariate nonparametric regression, and it is shown how these techniques can be used to uncover...... unknown functionality behind various phenomena in first engineering principles models using experimental data. The proposed modelling approach has significant application potential, e.g. for determining unknown reaction kinetics in both chemical and biological processes. To illustrate the performance...... of the approach, a case study is presented, which shows how an appropriate phenomena model for the growth rate of biomass in a fed-batch bioreactor can be inferred from data....
Directory of Open Access Journals (Sweden)
Annamaria Buonomano
2016-06-01
Full Text Available This paper presents numerical and experimental analyses aimed at evaluating the technical and economic feasibility of photovoltaic/thermal (PVT collectors. An experimental setup was purposely designed and constructed in order to compare the electrical performance of a PVT solar field with the one achieved by an identical solar field consisting of conventional photovoltaic (PV panels. The experimental analysis also aims at evaluating the potential advantages of PVT vs. PV in terms of enhancement of electrical efficiency and thermal energy production. The installed experimental set-up includes four flat polycrystalline silicon PV panels and four flat unglazed polycrystalline silicon PVT collectors. The total electrical power and area of the solar field are 2 kWe and 13 m2, respectively. The experimental set-up is currently installed at the company AV Project Ltd., located in Avellino (Italy. This study also analyzes the system from a numerical point of view, including a thermo-economic dynamic simulation model for the design and the assessment of energy performance and economic profitability of the solar systems consisting of glazed PVT and PV collectors. The experimental setup was modelled and partly simulated in TRNSYS environment. The simulation model was useful to analyze efficiencies and temperatures reached by such solar technologies, by taking into account the reference technology of PVTs (consisting of glazed collectors as well as to compare the numerical data obtained by dynamic simulations with the gathered experimental results for the PV technology. The numerical analysis shows that the PVT global efficiency is about 26%. Conversely, from the experimental point of view, the average thermal efficiency of PVT collectors is around 13% and the electrical efficiencies of both technologies are almost coincident and equal to 15%.
Biomedical Simulation Models of Human Auditory Processes
Bicak, Mehmet M. A.
2012-01-01
Detailed acoustic engineering models that explore noise propagation mechanisms associated with noise attenuation and transmission paths created when using hearing protectors such as earplugs and headsets in high noise environments. Biomedical finite element (FE) models are developed based on volume Computed Tomography scan data which provides explicit external ear, ear canal, middle ear ossicular bones and cochlea geometry. Results from these studies have enabled a greater understanding of hearing protector to flesh dynamics as well as prioritizing noise propagation mechanisms. Prioritization of noise mechanisms can form an essential framework for exploration of new design principles and methods in both earplug and earcup applications. These models are currently being used in development of a novel hearing protection evaluation system that can provide experimentally correlated psychoacoustic noise attenuation. Moreover, these FE models can be used to simulate the effects of blast related impulse noise on human auditory mechanisms and brain tissue.
Experimental models of demyelination and remyelination.
Torre-Fuentes, L; Moreno-Jiménez, L; Pytel, V; Matías-Guiu, J A; Gómez-Pinedo, U; Matías-Guiu, J
2017-08-29
Experimental animal models constitute a useful tool to deepen our knowledge of central nervous system disorders. In the case of multiple sclerosis, however, there is no such specific model able to provide an overview of the disease; multiple models covering the different pathophysiological features of the disease are therefore necessary. We reviewed the different in vitro and in vivo experimental models used in multiple sclerosis research. Concerning in vitro models, we analysed cell cultures and slice models. As for in vivo models, we examined such models of autoimmunity and inflammation as experimental allergic encephalitis in different animals and virus-induced demyelinating diseases. Furthermore, we analysed models of demyelination and remyelination, including chemical lesions caused by cuprizone, lysolecithin, and ethidium bromide; zebrafish; and transgenic models. Experimental models provide a deeper understanding of the different pathogenic mechanisms involved in multiple sclerosis. Choosing one model or another depends on the specific aims of the study. Copyright © 2017 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.
Advances in Intelligent Modelling and Simulation Simulation Tools and Applications
Oplatková, Zuzana; Carvalho, Marco; Kisiel-Dorohinicki, Marek
2012-01-01
The human capacity to abstract complex systems and phenomena into simplified models has played a critical role in the rapid evolution of our modern industrial processes and scientific research. As a science and an art, Modelling and Simulation have been one of the core enablers of this remarkable human trace, and have become a topic of great importance for researchers and practitioners. This book was created to compile some of the most recent concepts, advances, challenges and ideas associated with Intelligent Modelling and Simulation frameworks, tools and applications. The first chapter discusses the important aspects of a human interaction and the correct interpretation of results during simulations. The second chapter gets to the heart of the analysis of entrepreneurship by means of agent-based modelling and simulations. The following three chapters bring together the central theme of simulation frameworks, first describing an agent-based simulation framework, then a simulator for electrical machines, and...
MODELLING, SIMULATING AND OPTIMIZING BOILERS
DEFF Research Database (Denmark)
Sørensen, Kim; Condra, Thomas Joseph; Houbak, Niels
2004-01-01
In the present work a framework for optimizing the design of boilers for dynamic operation has been developed. A cost function to be minimized during the optimization has been formulated and for the present design variables related to the Boiler Volume and the Boiler load Gradient (i.e. ring rate...... on the boiler) have been dened. Furthermore a number of constraints related to: minimum and maximum boiler load gradient, minimum boiler size, Shrinking and Swelling and Steam Space Load have been dened. For dening the constraints related to the required boiler volume a dynamic model for simulating the boiler...... performance has been developed. Outputs from the simulations are shrinking and swelling of water level in the drum during for example a start-up of the boiler, these gures combined with the requirements with respect to allowable water level uctuations in the drum denes the requirements with respect to drum...
Modeling and simulation for micro DC motor based on simulink
Shen, Hanxin; Lei, Qiao; Chen, Wenxiang
2017-09-01
The micro DC motor has a large market demand but there is a lack of theoretical research for it. Through detailed analysis of the commutation process of micro DC motor commutator, based on micro DC motor electromagnetic torque equation and mechanical torque equation, with the help of Simulink toolkit, a triangle connection micro DC motor simulation model is established. By using the model, a sample micro DC motor are simulated, and an experimental measurements has been carried on the sample micro DC motor. It is found that the simulation results are consistent with theoretical analysis and experimental results.
SEMI Modeling and Simulation Roadmap
Energy Technology Data Exchange (ETDEWEB)
Hermina, W.L.
2000-10-02
With the exponential growth in the power of computing hardware and software, modeling and simulation is becoming a key enabler for the rapid design of reliable Microsystems. One vision of the future microsystem design process would include the following primary software capabilities: (1) The development of 3D part design, through standard CAD packages, with automatic design rule checks that guarantee the manufacturability and performance of the microsystem. (2) Automatic mesh generation, for 3D parts as manufactured, that permits computational simulation of the process steps, and the performance and reliability analysis for the final microsystem. (3) Computer generated 2D layouts for process steps that utilize detailed process models to generate the layout and process parameter recipe required to achieve the desired 3D part. (4) Science-based computational tools that can simulate the process physics, and the coupled thermal, fluid, structural, solid mechanics, electromagnetic and material response governing the performance and reliability of the microsystem. (5) Visualization software that permits the rapid visualization of 3D parts including cross-sectional maps, performance and reliability analysis results, and process simulation results. In addition to these desired software capabilities, a desired computing infrastructure would include massively parallel computers that enable rapid high-fidelity analysis, coupled with networked compute servers that permit computing at a distance. We now discuss the individual computational components that are required to achieve this vision. There are three primary areas of focus: design capabilities, science-based capabilities and computing infrastructure. Within each of these areas, there are several key capability requirements.
Atomic scale simulations for improved CRUD and fuel performance modeling
Energy Technology Data Exchange (ETDEWEB)
Andersson, Anders David Ragnar [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cooper, Michael William Donald [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-01-06
A more mechanistic description of fuel performance codes can be achieved by deriving models and parameters from atomistic scale simulations rather than fitting models empirically to experimental data. The same argument applies to modeling deposition of corrosion products on fuel rods (CRUD). Here are some results from publications in 2016 carried out using the CASL allocation at LANL.
Simulation and experimental study of resin flow in fibre fabrics
Yan, Fei; Yan, Shilin; Li, Yongjing
2017-06-01
Liquid Composite Moulding (LCM) is gradually becoming the most competitive manufacturing technology for producing large composite parts with complex geometry with high quality and low cost. These parts include those for airplanes, wind turbine blades and automobile components. Fibre fabrics in liquid composite moulding can be considered as dual-scale porous media. In different gap scales, an unsaturated flow is produced during the mould filling process. This particular flow behaviour deviates from the traditional Darcy’s law, which is used to calculate the filling pressure and will cause errors. According to sink theory, the unsaturated flow characteristics of this dual-scale porous media were studied in this paper, and a FEM solution program was developed. The results showed that the pressure curves against the position which simulated by sink functions were departure from the position of traditional theory. In addition, the simulation results of partially-saturated region were consistent with the experimental data.
Tokamak Simulation Code modeling of NSTX
International Nuclear Information System (INIS)
Jardin, S.C.; Kaye, S.; Menard, J.; Kessel, C.; Glasser, A.H.
2000-01-01
The Tokamak Simulation Code [TSC] is widely used for the design of new axisymmetric toroidal experiments. In particular, TSC was used extensively in the design of the National Spherical Torus eXperiment [NSTX]. The authors have now benchmarked TSC with initial NSTX results and find excellent agreement for plasma and vessel currents and magnetic flux loops when the experimental coil currents are used in the simulations. TSC has also been coupled with a ballooning stability code and with DCON to provide stability predictions for NSTX operation. TSC has also been used to model initial CHI experiments where a large poloidal voltage is applied to the NSTX vacuum vessel, causing a force-free current to appear in the plasma. This is a phenomenon that is similar to the plasma halo current that sometimes develops during a plasma disruption
Directory of Open Access Journals (Sweden)
Adriano Luiz de Paula
2011-01-01
Full Text Available Recognizing the importance of an adequate characterization of radar absorbing materials, and consequently their development, the present study aims to contribute for the establishment and validation of experimental determination and numerical simulation of electromagnetic materials complex permittivity and permeability, using a Teflon® sample. The present paper branches out into two related topics. The first one is concerned about the implementation of a computational modeling to predict the behavior of electromagnetic materials in confined environment by using electromagnetic three-dimensional simulation. The second topic re-examines the Nicolson-Ross-Weir mathematical model to retrieve the constitutive parameters (complex permittivity and permeability of a homogeneous sample (Teflon®, from scattering coefficient measurements. The experimental and simulated results show a good convergence that guarantees the application of the used methodologies for the characterization of different radar absorbing materials samples.
Improving the physiological realism of experimental models.
Vinnakota, Kalyan C; Cha, Chae Y; Rorsman, Patrik; Balaban, Robert S; La Gerche, Andre; Wade-Martins, Richard; Beard, Daniel A; Jeneson, Jeroen A L
2016-04-06
The Virtual Physiological Human (VPH) project aims to develop integrative, explanatory and predictive computational models (C-Models) as numerical investigational tools to study disease, identify and design effective therapies and provide an in silico platform for drug screening. Ultimately, these models rely on the analysis and integration of experimental data. As such, the success of VPH depends on the availability of physiologically realistic experimental models (E-Models) of human organ function that can be parametrized to test the numerical models. Here, the current state of suitable E-models, ranging from in vitro non-human cell organelles to in vivo human organ systems, is discussed. Specifically, challenges and recent progress in improving the physiological realism of E-models that may benefit the VPH project are highlighted and discussed using examples from the field of research on cardiovascular disease, musculoskeletal disorders, diabetes and Parkinson's disease.
Comparison of CFD simulations with experimental Jet Erosion Tests results
Mercier, F.; Bonelli, S.; Pinettes, P.; Golay, F.; Anselmet, F.; Philippe, P.
2014-01-01
The Jet Erosion Test (JET) is an experimental device increasingly used to quantify the resistance of soils to erosion. This resistance is characterised by two geotechnical parameters: the critical shear stress and the erosion coefficient. The JET interpretation model of Hanson and Cook (2004) provides an estimation of these erosion parameters. But Hanson's model is simplified, semi-empirical and several assumed hypotheses can be discussed. Our aim is to determine the relevance of the JET inte...
Simulated annealing model of acupuncture
Shang, Charles; Szu, Harold
2015-05-01
The growth control singularity model suggests that acupuncture points (acupoints) originate from organizers in embryogenesis. Organizers are singular points in growth control. Acupuncture can cause perturbation of a system with effects similar to simulated annealing. In clinical trial, the goal of a treatment is to relieve certain disorder which corresponds to reaching certain local optimum in simulated annealing. The self-organizing effect of the system is limited and related to the person's general health and age. Perturbation at acupoints can lead a stronger local excitation (analogous to higher annealing temperature) compared to perturbation at non-singular points (placebo control points). Such difference diminishes as the number of perturbed points increases due to the wider distribution of the limited self-organizing activity. This model explains the following facts from systematic reviews of acupuncture trials: 1. Properly chosen single acupoint treatment for certain disorder can lead to highly repeatable efficacy above placebo 2. When multiple acupoints are used, the result can be highly repeatable if the patients are relatively healthy and young but are usually mixed if the patients are old, frail and have multiple disorders at the same time as the number of local optima or comorbidities increases. 3. As number of acupoints used increases, the efficacy difference between sham and real acupuncture often diminishes. It predicted that the efficacy of acupuncture is negatively correlated to the disease chronicity, severity and patient's age. This is the first biological - physical model of acupuncture which can predict and guide clinical acupuncture research.
Operations planning simulation: Model study
1974-01-01
The use of simulation modeling for the identification of system sensitivities to internal and external forces and variables is discussed. The technique provides a means of exploring alternate system procedures and processes, so that these alternatives may be considered on a mutually comparative basis permitting the selection of a mode or modes of operation which have potential advantages to the system user and the operator. These advantages are measurements is system efficiency are: (1) the ability to meet specific schedules for operations, mission or mission readiness requirements or performance standards and (2) to accomplish the objectives within cost effective limits.
Numerical Simulation and Experimental Validation of the Inflation Test of Latex Balloons
Directory of Open Access Journals (Sweden)
Claudio Bustos
Full Text Available Abstract Experiments and modeling aimed at assessing the mechanical response of latex balloons in the inflation test are presented. To this end, the hyperelastic Yeoh material model is firstly characterized via tensile test and, then, used to numerically simulate via finite elements the stress-strain evolution during the inflation test. The numerical pressure-displacement curves are validated with those obtained experimentally. Moreover, this analysis is extended to a biomedical problem of an eyeball under glaucoma conditions.
Numerical Simulation and Experimental Validation of the Inflation Test of Latex Balloons
Bustos, Claudio; Herrera, Claudio García; Celentano, Diego; Chen, Daming; Cruchaga, Marcela
2016-01-01
Abstract Experiments and modeling aimed at assessing the mechanical response of latex balloons in the inflation test are presented. To this end, the hyperelastic Yeoh material model is firstly characterized via tensile test and, then, used to numerically simulate via finite elements the stress-strain evolution during the inflation test. The numerical pressure-displacement curves are validated with those obtained experimentally. Moreover, this analysis is extended to a biomedical problem of an...
Understanding Leadership: An Experimental-Experiential Model
Hole, George T.
2014-01-01
Books about leadership are dangerous to readers who fantasize about being leaders or apply leadership ideas as if they were proven formulas. As an antidote, I offer an experimental framework in which any leadership-management model can be tested to gain experiential understanding of the model. As a result one can gain reality-based insights about…
Numerical modeling and experimental validation of thermoplastic composites induction welding
Palmieri, Barbara; Nele, Luigi; Galise, Francesco
2018-05-01
In this work, a numerical simulation and experimental test of the induction welding of continuous fibre-reinforced thermoplastic composites (CFRTPCs) was provided. The thermoplastic Polyamide 66 (PA66) with carbon fiber fabric was used. Using a dedicated software (JMag Designer), the influence of the fundamental process parameters such as temperature, current and holding time was investigated. In order to validate the results of the simulations, and therefore the numerical model used, experimental tests were carried out, and the temperature values measured during the tests were compared with the aid of an optical pyrometer, with those provided by the numerical simulation. The mechanical properties of the welded joints were evaluated by single lap shear tests.
Simulation model of a PWR power plant
International Nuclear Information System (INIS)
Larsen, N.
1987-03-01
A simulation model of a hypothetical PWR power plant is described. A large number of disturbances and failures in plant function can be simulated. The model is written as seven modules to the modular simulation system for continuous processes DYSIM and serves also as a user example of this system. The model runs in Fortran 77 on the IBM-PC-AT. (author)
International Nuclear Information System (INIS)
Popescu, Lucretiu M.
2000-01-01
A computer code package (PTSIM) for particle transport Monte Carlo simulation was developed using object oriented techniques of design and programming. A flexible system for simulation of coupled photon, electron transport, facilitating development of efficient simulation applications, was obtained. For photons: Compton and photo-electric effects, pair production and Rayleigh interactions are simulated, while for electrons, a class II condensed history scheme was considered, in which catastrophic interactions (Moeller electron-electron interaction, bremsstrahlung, etc.) are treated in detail and all other interactions with reduced individual effect on electron history are grouped together using continuous slowing down approximation and energy straggling theories. Electron angular straggling is simulated using Moliere theory or a mixed model in which scatters at large angles are treated as distinct events. Comparisons with experimentally benchmarks for electron transmission and bremsstrahlung emissions energy and angular spectra, and for dose calculations are presented
Application of Hidden Markov Models in Biomolecular Simulations.
Shukla, Saurabh; Shamsi, Zahra; Moffett, Alexander S; Selvam, Balaji; Shukla, Diwakar
2017-01-01
Hidden Markov models (HMMs) provide a framework to analyze large trajectories of biomolecular simulation datasets. HMMs decompose the conformational space of a biological molecule into finite number of states that interconvert among each other with certain rates. HMMs simplify long timescale trajectories for human comprehension, and allow comparison of simulations with experimental data. In this chapter, we provide an overview of building HMMs for analyzing bimolecular simulation datasets. We demonstrate the procedure for building a Hidden Markov model for Met-enkephalin peptide simulation dataset and compare the timescales of the process.
Bridging experiments, models and simulations
DEFF Research Database (Denmark)
Carusi, Annamaria; Burrage, Kevin; Rodríguez, Blanca
2012-01-01
Computational models in physiology often integrate functional and structural information from a large range of spatiotemporal scales from the ionic to the whole organ level. Their sophistication raises both expectations and skepticism concerning how computational methods can improve our...... understanding of living organisms and also how they can reduce, replace, and refine animal experiments. A fundamental requirement to fulfill these expectations and achieve the full potential of computational physiology is a clear understanding of what models represent and how they can be validated. The present...... that contributes to defining the specific aspects of cardiac electrophysiology the MSE system targets, rather than being only an external test, and that this is driven by advances in experimental and computational methods and the combination of both....
Experimental Validation of a Dynamic Model for Lightweight Robots
Directory of Open Access Journals (Sweden)
Alessandro Gasparetto
2013-03-01
Full Text Available Nowadays, one of the main topics in robotics research is dynamic performance improvement by means of a lightening of the overall system structure. The effective motion and control of these lightweight robotic systems occurs with the use of suitable motion planning and control process. In order to do so, model-based approaches can be adopted by exploiting accurate dynamic models that take into account the inertial and elastic terms that are usually neglected in a heavy rigid link configuration. In this paper, an effective method for modelling spatial lightweight industrial robots based on an Equivalent Rigid Link System approach is considered from an experimental validation perspective. A dynamic simulator implementing the formulation is used and an experimental test-bench is set-up. Experimental tests are carried out with a benchmark L-shape mechanism.
Li, Peng; Jiang, Shengyuan; Tang, Dewei; Xu, Bo
2017-05-01
For sake of striking a balance between the need of drilling efficiency and the constrains of power budget on the moon, the penetrations per revolution of drill bit are generally limited in the range around 0.1 mm, and besides the geometric angle of the cutting blade need to be well designed. This paper introduces a simulation approach based on PFC3D (particle flow code 3 dimensions) for analyzing the cutting load feature on lunar rock simulant, which is derived from different geometric-angle blades with a small cutting depth. The mean values of the cutting force of five blades in the survey region (four on the boundary points and one on the center point) are selected as the macroscopic responses of model. The method of experimental design which includes Plackett-Burman (PB) design and central composite design (CCD) method is adopted in the matching procedure of microparameters in PFC model. Using the optimization method of enumeration, the optimum set of microparameters is acquired. Then, the experimental validation is implemented by using other twenty-five blades with different geometric angles, and the results from both simulations and laboratory tests give fair agreements. Additionally, the rock breaking process cut by different blades are quantified from simulation analysis. This research provides the theoretical support for the refinement of the rock cutting load prediction and the geometric design of cutting blade on the drill bit.
Simulation and experimental validation of the performance of a absorption refrigerator
International Nuclear Information System (INIS)
Olbricht, Michael; Luke, Andrea
2015-01-01
The two biggest obstacles to a stronger market penetration of absorption refrigerators are their high cost and the size of the apparatus, which are due to the inaccurate methods for plant design. In order to contribute to an improved design a thermodynamic model is presented to describe the performance of a absorption refrigerator with the working fluid water/lithium. In this model, the processes are displayed in the single apparatus and coupled to each other in the systemic context. Thereby the interactions between the apparatus can specifically investigated and thus the process limiting component can be identified under the respective conditions. A validation of the simulation model and the boundary conditions used is done based on experimental data operating a self-developed absorption refrigerator. In the simulation, the heat transfer surfaces in accordance with the real system can be specified. The heat transport is taken into account based on typical values for the heat transfer in the individual apparatuses. Simulation results show good agreement with the experimental data. The physical relationships and influences externally defined operating parameters are correctly reproduced. Due to the chosen low heat transfer coefficient, the calculated cooling capacities by the model are below the experimentally measured. Finally, the possibilities and limitations are discussed by using the model and further improvement possibilities are suggested. [de
Object Oriented Toolbox for Modelling and Simulation of Dynamical Systems
DEFF Research Database (Denmark)
Poulsen, Mikael Zebbelin; Wagner, Falko Jens; Thomsen, Per Grove
1998-01-01
This paper presents the results of an ongoing project, dealing with design and implementation of a simulation toolbox based on object oriented modelling techniques. The paper describes an experimental implementation of parts of such a toolbox in C++, and discusses the experiences drawn from that ...... that process. Essential to the work is the focus on simulation of complex dynamical systems, from modelling the single components/subsystems to building complete systemssuch a toolbox in C++, and discusses the experiences drawn from that process....
Monte Carlo simulation and experimental verification of radiotherapy electron beams
International Nuclear Information System (INIS)
Griffin, J.; Deloar, H. M.
2007-01-01
Full text: Based on fundamental physics and statistics, the Monte Carlo technique is generally accepted as the accurate method for modelling radiation therapy treatments. A Monte Carlo simulation system has been installed, and models of linear accelerators in the more commonly used electron beam modes have been built and commissioned. A novel technique for radiation dosimetry is also being investigated. Combining the advantages of both water tank and solid phantom dosimetry, a hollow, thin walled shell or mask is filled with water and then raised above the natural water surface to produce a volume of water with the desired irregular shape.
EXPERIMENTAL MODEL OF THE PRIMARY MALE HYPOGONADISM
Directory of Open Access Journals (Sweden)
P. A. Kulikova
2014-01-01
Full Text Available Background: Development of the new methods of treatment of primary male hypogonadism is an urgent medical problem. Its solution requires a suitable experimental model of the disease. Aim: The creation of new experimental model of primary male hypogonadism. Materials and methods: The study was conducted on the male Wistar rats, hypogonadism was modeled by temporary ligation of the distal part of the spermatic cord. Results: It was shown that three-day ligation of the spermatic cord led to persistent disturbance of the testosterone-producing and reproductive functions. These manifestations were reversible at shorter duration of the exposure. Conclusion: The created model of primary male hypogonadism is characterized by the persistent testosterone-producing and reproductive functions disturbance, technical availability, non-toxicity to the other organs and systems. Availability of the model provides new opportunities for the development of approaches to treating diseases of the reproductive organs in men.
Galaxy Alignments: Theory, Modelling & Simulations
Kiessling, Alina; Cacciato, Marcello; Joachimi, Benjamin; Kirk, Donnacha; Kitching, Thomas D.; Leonard, Adrienne; Mandelbaum, Rachel; Schäfer, Björn Malte; Sifón, Cristóbal; Brown, Michael L.; Rassat, Anais
2015-11-01
The shapes of galaxies are not randomly oriented on the sky. During the galaxy formation and evolution process, environment has a strong influence, as tidal gravitational fields in the large-scale structure tend to align nearby galaxies. Additionally, events such as galaxy mergers affect the relative alignments of both the shapes and angular momenta of galaxies throughout their history. These "intrinsic galaxy alignments" are known to exist, but are still poorly understood. This review will offer a pedagogical introduction to the current theories that describe intrinsic galaxy alignments, including the apparent difference in intrinsic alignment between early- and late-type galaxies and the latest efforts to model them analytically. It will then describe the ongoing efforts to simulate intrinsic alignments using both N-body and hydrodynamic simulations. Due to the relative youth of this field, there is still much to be done to understand intrinsic galaxy alignments and this review summarises the current state of the field, providing a solid basis for future work.
Experimental and simulation analysis of hydrogen production by partial oxidation of methanol
Energy Technology Data Exchange (ETDEWEB)
Sikander, U. [National Univ. of Science and Technology, Islamabad (Pakistan)
2014-10-15
Partial oxidation of methanol is the only self-sustaining process for onboard production of hydrogen. For this a fixed bed catalytic reactor is designed, based on heterogeneous catalytic reaction. To develop an optimized process, simulation is carried out using ASPEN HYSYS v 7.1. Reaction kinetics is developed on the basis of Langmuir Hinshel wood model. 45:55:5 of CuO: ZnO: Al/sub 2/O/sub 3/ is used as a catalyst. Simulation results are studied in detail to understand the phenomenon of partial oxidation of methanol inside the reactor. An experimental rig is developed for hydrogen production through partial oxidation of methanol. Results obtained from process simulation and experimental work; are compared with each other. (author)
Simulations of argon accident scenarios in the ATLAS experimental cavern a safety analysis
Balda, F
2002-01-01
Some characteristic accidents in the ATLAS experimental cavern (UX15) are simulated by means of STAR-CD, a code using the "Finite-Volume" method. These accidents involve different liquid argon leaks from the barrel cryostat of the detector, thus causing the dispersion of the argon into the Muon Chamber region and the evaporation of the liquid. The subsequent temperature gradients and distribution of argon concentrations, as well as their evolution in time are simulated and discussed, with the purpose of analysing the dangers related to asphyxiation and to contact with cryogenic fluids for the working personnel. A summary of the theory that stands behind the code is also given. In order to validate the models, an experimental test on a liquid argon spill performed earlier is simulated, showing that the program is able to output reliable results. At the end, some safety-related recommendations are listed.
Modeling of Experimental Adsorption Isotherm Data
Directory of Open Access Journals (Sweden)
Xunjun Chen
2015-01-01
Full Text Available Adsorption is considered to be one of the most effective technologies widely used in global environmental protection areas. Modeling of experimental adsorption isotherm data is an essential way for predicting the mechanisms of adsorption, which will lead to an improvement in the area of adsorption science. In this paper, we employed three isotherm models, namely: Langmuir, Freundlich, and Dubinin-Radushkevich to correlate four sets of experimental adsorption isotherm data, which were obtained by batch tests in lab. The linearized and non-linearized isotherm models were compared and discussed. In order to determine the best fit isotherm model, the correlation coefficient (r2 and standard errors (S.E. for each parameter were used to evaluate the data. The modeling results showed that non-linear Langmuir model could fit the data better than others, with relatively higher r2 values and smaller S.E. The linear Langmuir model had the highest value of r2, however, the maximum adsorption capacities estimated from linear Langmuir model were deviated from the experimental data.
An Interactive Multimedia Based Instruction in Experimental Modelling
DEFF Research Database (Denmark)
Knudsen, Morten; Nielsen, J.N.; Østergaard, J.
1997-01-01
A CD-ROM based interactive multimedia instruction in experimental modelling for Danish Engineering School teachers is described. The content is based on a new sensitivity approach for direct estimation of physical parameters in linear and nonlinear dynamic systems. The presentation is inspired of...... of Solomans=s inventory of learning styles. To enhance active learning and motivation by real life problems, the simulation tool Matlab is integrated in the authoring program Medi8or....
Energy Technology Data Exchange (ETDEWEB)
Olbricht, Michael; Luke, Andrea [Kassel Univ. (Germany). Fachgebiet Technische Thermodynamik
2015-07-01
The two biggest obstacles to a stronger market penetration of absorption refrigerators are their high cost and the size of the apparatus, which are due to the inaccurate methods for plant design. In order to contribute to an improved design a thermodynamic model is presented to describe the performance of a absorption refrigerator with the working fluid water/lithium. In this model, the processes are displayed in the single apparatus and coupled to each other in the systemic context. Thereby the interactions between the apparatus can specifically investigated and thus the process limiting component can be identified under the respective conditions. A validation of the simulation model and the boundary conditions used is done based on experimental data operating a self-developed absorption refrigerator. In the simulation, the heat transfer surfaces in accordance with the real system can be specified. The heat transport is taken into account based on typical values for the heat transfer in the individual apparatuses. Simulation results show good agreement with the experimental data. The physical relationships and influences externally defined operating parameters are correctly reproduced. Due to the chosen low heat transfer coefficient, the calculated cooling capacities by the model are below the experimentally measured. Finally, the possibilities and limitations are discussed by using the model and further improvement possibilities are suggested. [German] Die beiden groessten Hemmnisse fuer eine staerkere Marktdurchdringung von Absorptionskaeltemaschinen (AKM) sind deren hohe Anschaffungskosten sowie die Baugroesse der Apparate, die durch die ungenauen Methoden zur Anlagenauslegung begruendet sind. Als Beitrag fuer eine verbesserte Auslegung wird ein thermodynamisches Modell zur Beschreibung des Betriebsverhaltens einer AKM mit dem Arbeitsstoffpaar Wasser/Lithiumbromid vorgestellt. In diesem werden die Prozesse in den Einzelapparaten abgebildet und im systemischen
Development of a fault test experimental facility model using Matlab
Energy Technology Data Exchange (ETDEWEB)
Pereira, Iraci Martinez; Moraes, Davi Almeida, E-mail: martinez@ipen.br, E-mail: dmoraes@dk8.com.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)
2015-07-01
The Fault Test Experimental Facility was developed to simulate a PWR nuclear power plant and is instrumented with temperature, level and pressure sensors. The Fault Test Experimental Facility can be operated to generate normal and fault data, and these failures can be added initially small, and their magnitude being increasing gradually. This work presents the Fault Test Experimental Facility model developed using the Matlab GUIDE (Graphical User Interface Development Environment) toolbox that consists of a set of functions designed to create interfaces in an easy and fast way. The system model is based on the mass and energy inventory balance equations. Physical as well as operational aspects are taken into consideration. The interface layout looks like a process flowchart and the user can set the input variables. Besides the normal operation conditions, there is the possibility to choose a faulty variable from a list. The program also allows the user to set the noise level for the input variables. Using the model, data were generated for different operational conditions, both under normal and fault conditions with different noise levels added to the input variables. Data generated by the model will be compared with Fault Test Experimental Facility data. The Fault Test Experimental Facility theoretical model results will be used for the development of a Monitoring and Fault Detection System. (author)
Development of a fault test experimental facility model using Matlab
International Nuclear Information System (INIS)
Pereira, Iraci Martinez; Moraes, Davi Almeida
2015-01-01
The Fault Test Experimental Facility was developed to simulate a PWR nuclear power plant and is instrumented with temperature, level and pressure sensors. The Fault Test Experimental Facility can be operated to generate normal and fault data, and these failures can be added initially small, and their magnitude being increasing gradually. This work presents the Fault Test Experimental Facility model developed using the Matlab GUIDE (Graphical User Interface Development Environment) toolbox that consists of a set of functions designed to create interfaces in an easy and fast way. The system model is based on the mass and energy inventory balance equations. Physical as well as operational aspects are taken into consideration. The interface layout looks like a process flowchart and the user can set the input variables. Besides the normal operation conditions, there is the possibility to choose a faulty variable from a list. The program also allows the user to set the noise level for the input variables. Using the model, data were generated for different operational conditions, both under normal and fault conditions with different noise levels added to the input variables. Data generated by the model will be compared with Fault Test Experimental Facility data. The Fault Test Experimental Facility theoretical model results will be used for the development of a Monitoring and Fault Detection System. (author)
Biomass thermochemical gasification: Experimental studies and modeling
Kumar, Ajay
The overall goals of this research were to study the biomass thermochemical gasification using experimental and modeling techniques, and to evaluate the cost of industrial gas production and combined heat and power generation. This dissertation includes an extensive review of progresses in biomass thermochemical gasification. Product gases from biomass gasification can be converted to biopower, biofuels and chemicals. However, for its viable commercial applications, the study summarizes the technical challenges in the gasification and downstream processing of product gas. Corn stover and dried distillers grains with solubles (DDGS), a non-fermentable byproduct of ethanol production, were used as the biomass feedstocks. One of the objectives was to determine selected physical and chemical properties of corn stover related to thermochemical conversion. The parameters of the reaction kinetics for weight loss were obtained. The next objective was to investigate the effects of temperature, steam to biomass ratio and equivalence ratio on gas composition and efficiencies. DDGS gasification was performed on a lab-scale fluidized-bed gasifier with steam and air as fluidizing and oxidizing agents. Increasing the temperature resulted in increases in hydrogen and methane contents and efficiencies. A model was developed to simulate the performance of a lab-scale gasifier using Aspen Plus(TM) software. Mass balance, energy balance and minimization of Gibbs free energy were applied for the gasification to determine the product gas composition. The final objective was to optimize the process by maximizing the net energy efficiency, and to estimate the cost of industrial gas, and combined heat and power (CHP) at a biomass feedrate of 2000 kg/h. The selling price of gas was estimated to be 11.49/GJ for corn stover, and 13.08/GJ for DDGS. For CHP generation, the electrical and net efficiencies were 37 and 86%, respectively for corn stover, and 34 and 78%, respectively for DDGS. For
Experimental study and simulations of infiltration in evapotranspiration landfill covers
Directory of Open Access Journals (Sweden)
Wen-xian Zhang
2009-09-01
Full Text Available Various cover systems have been designed for landfill sites in order to minimize infiltration (percolation into the underlying waste. This study evaluated the soil water balance performance of evapotranspiration covers (ET covers and simulated percolation in the systems using the active region model (ARM. Experiments were conducted to measure water flow processes and water balance components in a bare soil cover and different ET covers. Results showed that vegetation played a critical role in controlling the water balance of the ET covers. In soil profiles of 60-cm depth with and without vegetation cover, the maximum soil water storage capacities were 97.2 mm and 62.8 mm, respectively. The percolation amount in the bare soil was 2.1 times that in the vegetation-covered soil. The ARM simulated percolation more accurately than the continuum model because it considered preferential flow. Numerical simulation results also indicated that using the ET cover system was an effective way of removing water through evapotranspiration, thus reducing percolation.
Beam equipment electromagnetic interaction in accelerators: simulation and experimental benchmarking
Passarelli, Andrea; Vaccaro, Vittorio Giorgio; Massa, Rita; Masullo, Maria Rosaria
One of the most significant technological problems to achieve the nominal performances in the Large Hadron Collider (LHC) concerns the system of collimation of particle beams. The use of collimators crystals, exploiting the channeling effect on extracted beam, has been experimentally demonstrated. The first part of this thesis is about the optimization of UA9 goniometer at CERN, this device used for beam collimation will replace a part of the vacuum chamber. The optimization process, however, requires the calculation of the coupling impedance between the circulating beam and this structure in order to define the threshold of admissible intensity to do not trigger instability processes. Simulations have been performed with electromagnetic codes to evaluate the coupling impedance and to assess the beam-structure interaction. The results clearly showed that the most concerned resonance frequencies are due solely to the open cavity to the compartment of the motors and position sensors considering the crystal in o...
International Nuclear Information System (INIS)
Anith Khairunnisa Ghazali; Mohd Sabri Minhat
2015-01-01
Reactor TRIGA PUSPATI (RTP) undergoes safe operation for more than 30 years and the only research reactor in Malaysia. The main safety feature of Instrumentation and Control (I and C) system design is such that any failure in the electronic, or its associated components, does not lead to an uncontrolled rate of reactivity. There are no best models for RTP simulation was designed for study and research. Therefore, the comparison for I&C parameters are very essential, to design the best RTP model using MATLAB/ Simulink as close as the RTP. The simulation of TRIGA reactor type already develop using desktop reactor simulator such as Personal Computer Transient Analyzer (PCTRAN). The experimental data from RTP and simulation of PCTRAN shows some similarities and differences due to certain limitation. Currently, the structured RTP simulation was designed using MATLAB and Simulink tool that consist of ideal fission chamber, controller, control rod position, height to worth and RTP model. The study on this paper focus on comparison between real data from RTP and simulation result from PCTRAN on I&C parameters such as water level, fuel temperature, bulk temperature, power rated and rod position. The error analysis due to some similarities and differences of I&C parameters shall be obtained and analysed. The result will be used as reference for proposed new structured of RTP model. (author)
Hemorrhoids: an experimental model in monkeys
Directory of Open Access Journals (Sweden)
Plapler Hélio
2006-01-01
Full Text Available PURPOSE: Hemorrhoids are a matter of concern due to a painful outcome. We describe a simple, easy and reliable experimental model to produce hemorrhoids in monkeys. METHODS: 14 monkeys (Cebus apella were used. After general anesthesia, hemorrhoids were induced by ligation of the inferior hemorrhoidal vein, which is very alike to humans. The vein was located through a perianal incision, dissected and ligated with a 3-0 vicryl. The skin was sutured with a 4-0 catgut thread. Animals were kept in appropriate cages and evaluated daily. RESULTS: Nine days later there were hemorrhoidal piles in the anus in fifty percent (50% of the animals. Outcome was unremarkable. There was no bleeding and all animals showed no signs of pain or suffering. CONCLUSION: This is an affordable and reliable experimental model to induce hemorrhoids for experimental studies.
THE MARK I BUSINESS SYSTEM SIMULATION MODEL
of a large-scale business simulation model as a vehicle for doing research in management controls. The major results of the program were the...development of the Mark I business simulation model and the Simulation Package (SIMPAC). SIMPAC is a method and set of programs facilitating the construction...of large simulation models. The object of this document is to describe the Mark I Corporation model, state why parts of the business were modeled as they were, and indicate the research applications of the model. (Author)
Statistical 3D damage accumulation model for ion implant simulators
Hernandez-Mangas, J M; Enriquez, L E; Bailon, L; Barbolla, J; Jaraiz, M
2003-01-01
A statistical 3D damage accumulation model, based on the modified Kinchin-Pease formula, for ion implant simulation has been included in our physically based ion implantation code. It has only one fitting parameter for electronic stopping and uses 3D electron density distributions for different types of targets including compound semiconductors. Also, a statistical noise reduction mechanism based on the dose division is used. The model has been adapted to be run under parallel execution in order to speed up the calculation in 3D structures. Sequential ion implantation has been modelled including previous damage profiles. It can also simulate the implantation of molecular and cluster projectiles. Comparisons of simulated doping profiles with experimental SIMS profiles are presented. Also comparisons between simulated amorphization and experimental RBS profiles are shown. An analysis of sequential versus parallel processing is provided.
Statistical 3D damage accumulation model for ion implant simulators
International Nuclear Information System (INIS)
Hernandez-Mangas, J.M.; Lazaro, J.; Enriquez, L.; Bailon, L.; Barbolla, J.; Jaraiz, M.
2003-01-01
A statistical 3D damage accumulation model, based on the modified Kinchin-Pease formula, for ion implant simulation has been included in our physically based ion implantation code. It has only one fitting parameter for electronic stopping and uses 3D electron density distributions for different types of targets including compound semiconductors. Also, a statistical noise reduction mechanism based on the dose division is used. The model has been adapted to be run under parallel execution in order to speed up the calculation in 3D structures. Sequential ion implantation has been modelled including previous damage profiles. It can also simulate the implantation of molecular and cluster projectiles. Comparisons of simulated doping profiles with experimental SIMS profiles are presented. Also comparisons between simulated amorphization and experimental RBS profiles are shown. An analysis of sequential versus parallel processing is provided
DSMC simulation and experimental validation of shock interaction in hypersonic low density flow.
Xiao, Hong; Shang, Yuhe; Wu, Di
2014-01-01
Direct simulation Monte Carlo (DSMC) of shock interaction in hypersonic low density flow is developed. Three collision molecular models, including hard sphere (HS), variable hard sphere (VHS), and variable soft sphere (VSS), are employed in the DSMC study. The simulations of double-cone and Edney's type IV hypersonic shock interactions in low density flow are performed. Comparisons between DSMC and experimental data are conducted. Investigation of the double-cone hypersonic flow shows that three collision molecular models can predict the trend of pressure coefficient and the Stanton number. HS model shows the best agreement between DSMC simulation and experiment among three collision molecular models. Also, it shows that the agreement between DSMC and experiment is generally good for HS and VHS models in Edney's type IV shock interaction. However, it fails in the VSS model. Both double-cone and Edney's type IV shock interaction simulations show that the DSMC errors depend on the Knudsen number and the models employed for intermolecular interaction. With the increase in the Knudsen number, the DSMC error is decreased. The error is the smallest in HS compared with those in the VHS and VSS models. When the Knudsen number is in the level of 10(-4), the DSMC errors, for pressure coefficient, the Stanton number, and the scale of interaction region, are controlled within 10%.
Numerical Simulation and Experimental Study of Deep Bed Corn Drying Based on Water Potential
Directory of Open Access Journals (Sweden)
Zhe Liu
2015-01-01
Full Text Available The concept and the model of water potential, which were widely used in agricultural field, have been proved to be beneficial in the application of vacuum drying model and have provided a new way to explore the grain drying model since being introduced to grain drying and storage fields. Aiming to overcome the shortcomings of traditional deep bed drying model, for instance, the application range of this method is narrow and such method does not apply to systems of which pressure would be an influential factor such as vacuum drying system in a way combining with water potential drying model. This study established a numerical simulation system of deep bed corn drying process which has been proved to be effective according to the results of numerical simulation and corresponding experimental investigation and has revealed that desorption and adsorption coexist in deep bed drying.
Optimal Experimental Design for Model Discrimination
Myung, Jay I.; Pitt, Mark A.
2009-01-01
Models of a psychological process can be difficult to discriminate experimentally because it is not easy to determine the values of the critical design variables (e.g., presentation schedule, stimulus structure) that will be most informative in differentiating them. Recent developments in sampling-based search methods in statistics make it…
SiO2-Ta2O5 sputtering yields: simulated and experimental results
International Nuclear Information System (INIS)
Vireton, E.; Ganau, P.; Mackowski, J.M.; Michel, C.; Pinard, L.; Remillieux, A.
1994-09-01
To improve mirrors coating, we have modeled sputtering of binary oxide targets using TRIM code. First, we have proposed a method to calculate TRIM input parameters using on the one hand thermodynamic cycle and on the other hand Malherbe's results. Secondly, an iterative processing has provided for oxide steady targets caused by ionic bombardment. Thirdly, we have exposed a model to get experimental sputtering yields. Fourthly, for (Ar - SiO 2 ) pair, we have determined that steady target is a silica one. A good agreement between simulated and experimental yields versus ion incident angle has been found. For (Ar - Ta 2 O 5 ) pair, we have to introduce preferential sputtering concept to explain discrepancy between simulation and experiment. In this case, steady target is tantalum monoxide. For (Ar - Ta(+O 2 ) pair, tantalum sputtered by argon ions in reactive oxygen atmosphere, we have to take into account new concept of oxidation stimulated by ion beam. We have supposed that tantalum target becomes a Ta 2 O 5 one in reactive oxygen atmosphere. Then, following mechanism is similar to previous pair. We have obtained steady target of tantalum monoxide too. Comparison between simulated and experimental sputtering yields versus ion incident angle has given very good agreement. By simulation, we have found that tantalum monoxide target has at least 15 angstrom thickness. Those results are compatible with Malherbe's and Taglauer's ones. (authors)
Vivio, Francesco; Fanelli, Pierluigi; Ferracci, Michele
2018-03-01
In aeronautical and automotive industries the use of rivets for applications requiring several joining points is now very common. In spite of a very simple shape, a riveted junction has many contact surfaces and stress concentrations that make the local stiffness very difficult to be calculated. To overcome this difficulty, commonly finite element models with very dense meshes are performed for single joint analysis because the accuracy is crucial for a correct structural analysis. Anyhow, when several riveted joints are present, the simulation becomes computationally too heavy and usually significant restrictions to joint modelling are introduced, sacrificing the accuracy of local stiffness evaluation. In this paper, we tested the accuracy of a rivet finite element presented in previous works by the authors. The structural behaviour of a lap joint specimen with a rivet joining is simulated numerically and compared to experimental measurements. The Rivet Element, based on a closed-form solution of a reference theoretical model of the rivet joint, simulates local and overall stiffness of the junction combining high accuracy with low degrees of freedom contribution. In this paper the Rivet Element performances are compared to that of a FE non-linear model of the rivet, built with solid elements and dense mesh, and to experimental data. The promising results reported allow to consider the Rivet Element able to simulate, with a great accuracy, actual structures with several rivet connections.
Distributed simulation a model driven engineering approach
Topçu, Okan; Oğuztüzün, Halit; Yilmaz, Levent
2016-01-01
Backed by substantive case studies, the novel approach to software engineering for distributed simulation outlined in this text demonstrates the potent synergies between model-driven techniques, simulation, intelligent agents, and computer systems development.
Benchmark simulation models, quo vadis?
Jeppsson, U; Alex, J; Batstone, D J; Benedetti, L; Comas, J; Copp, J B; Corominas, L; Flores-Alsina, X; Gernaey, K V; Nopens, I; Pons, M-N; Rodríguez-Roda, I; Rosen, C; Steyer, J-P; Vanrolleghem, P A; Volcke, E I P; Vrecko, D
2013-01-01
As the work of the IWA Task Group on Benchmarking of Control Strategies for wastewater treatment plants (WWTPs) is coming to an end, it is essential to disseminate the knowledge gained. For this reason, all authors of the IWA Scientific and Technical Report on benchmarking have come together to provide their insights, highlighting areas where knowledge may still be deficient and where new opportunities are emerging, and to propose potential avenues for future development and application of the general benchmarking framework and its associated tools. The paper focuses on the topics of temporal and spatial extension, process modifications within the WWTP, the realism of models, control strategy extensions and the potential for new evaluation tools within the existing benchmark system. We find that there are major opportunities for application within all of these areas, either from existing work already being done within the context of the benchmarking simulation models (BSMs) or applicable work in the wider literature. Of key importance is increasing capability, usability and transparency of the BSM package while avoiding unnecessary complexity.
Simulation modelling of fynbos ecosystems: Systems analysis and conceptual models
CSIR Research Space (South Africa)
Kruger, FJ
1985-03-01
Full Text Available -animal interactions. An additional two models, which expand aspects of the FYNBOS model, are described: a model for simulating canopy processes; and a Fire Recovery Simulator. The canopy process model will simulate ecophysiological processes in more detail than FYNBOS...
NUMERICAL SIMULATION AND EXPERIMENTAL STUDY OF DRAGREDUCING SURFACE OF A REAL SHARK SKIN*
Institute of Scientific and Technical Information of China (English)
ZHANG De-yuan; LUO Yue-hao; LI Xiang; CHEN Hua-wei
2011-01-01
It is well known that shark skin surface can effectively inhabit the occurrence of turbulence and reduce the wall friction,but in order to understand the mechanism of drag reduction, one has to solve the problem of the turbulent flow on grooved-scale surface, and in that respect, the direct numerical simulation is an important tool.In this article, based on the real biological shark skin,the model of real shark skin is built through high-accurate scanning and data processing.The turbulent flow on a real shark skin is comprehensively simulated, and based on the simulation, the drag reduction mechanism is discussed.In addition, in order to validate the drag-reducing effect of shark skin surface, actual experiments were carried out in water tunnel, and the experimental results are approximately consistent with the numerical simulation.
Design and simulation experimental study of bracket plates in steam generator for AC600 PWR
International Nuclear Information System (INIS)
Zhang Fuyuan; Zhang Wenqi; Ji Quankai; Zeng Xi; Xie Yongyao
1998-01-01
Seven-holes type bracket plate at the inlet nozzle and three-holes taper bracket plate at outlet nozzle are designed. According to 'local form and structure change' simulation theory, hydraulic models and simulators for the simulative experiments are designed. Taking water as the medium, the simulative experiments have been completed at the room temperature. The ζ-Re curves (here, ζ is the local pressure loss coefficient at the nozzles after the bracket plates are installed and Re is Reynolds number) have been got. Based on the experimental results, the computation and the analysis have been shown that. If the bracket plates are used in the steam generator (SG) of AC600 PWR, the pressure drop of primary side in the SG is about 14 percent higher than that of the 55/19 B style SG
Experimental and Monte Carlo simulated spectra of a liquid-metal-jet x-ray source
International Nuclear Information System (INIS)
Marziani, M.; Gambaccini, M.; Di Domenico, G.; Taibi, A.; Cardarelli, P.
2014-01-01
A prototype x-ray system based on a liquid-metal-jet anode was evaluated within the framework of the LABSYNC project. The generated spectrum was measured using a CZT-based spectrometer and was compared with spectra simulated by three Monte Carlo codes: MCNPX, PENELOPE and EGS5. Notable differences in the simulated spectra were found. These are mainly attributable to differences in the models adopted for the electron-impact ionization cross section. The simulation that more closely reproduces the experimentally measured spectrum was provided by PENELOPE. - Highlights: • The x-ray spectrum of a liquid-jet x-ray anode was measured with a CZT spectrometer. • Results were compared with Monte Carlo simulations using MCNPX, PENELOPE, EGS5. • Notable differences were found among the Monte Carlo simulated spectra. • The key role was played by the electron-impact ionization cross-section model used. • The experimentally measured spectrum was closely reproduced by the PENELOPE code
Macrophages and Uveitis in Experimental Animal Models
Directory of Open Access Journals (Sweden)
Salvador Mérida
2015-01-01
Full Text Available Resident and infiltrated macrophages play relevant roles in uveitis as effectors of innate immunity and inductors of acquired immunity. They are major effectors of tissue damage in uveitis and are also considered to be potent antigen-presenting cells. In the last few years, experimental animal models of uveitis have enabled us to enhance our understanding of the leading role of macrophages in eye inflammation processes, including macrophage polarization in experimental autoimmune uveoretinitis and the major role of Toll-like receptor 4 in endotoxin-induced uveitis. This improved knowledge should guide advantageous iterative research to establish mechanisms and possible therapeutic targets for human uveitis resolution.
An introduction to enterprise modeling and simulation
Energy Technology Data Exchange (ETDEWEB)
Ostic, J.K.; Cannon, C.E. [Los Alamos National Lab., NM (United States). Technology Modeling and Analysis Group
1996-09-01
As part of an ongoing effort to continuously improve productivity, quality, and efficiency of both industry and Department of Energy enterprises, Los Alamos National Laboratory is investigating various manufacturing and business enterprise simulation methods. A number of enterprise simulation software models are being developed to enable engineering analysis of enterprise activities. In this document the authors define the scope of enterprise modeling and simulation efforts, and review recent work in enterprise simulation at Los Alamos National Laboratory as well as at other industrial, academic, and research institutions. References of enterprise modeling and simulation methods and a glossary of enterprise-related terms are provided.
Simulation and Modeling Methodologies, Technologies and Applications
Filipe, Joaquim; Kacprzyk, Janusz; Pina, Nuno
2014-01-01
This book includes extended and revised versions of a set of selected papers from the 2012 International Conference on Simulation and Modeling Methodologies, Technologies and Applications (SIMULTECH 2012) which was sponsored by the Institute for Systems and Technologies of Information, Control and Communication (INSTICC) and held in Rome, Italy. SIMULTECH 2012 was technically co-sponsored by the Society for Modeling & Simulation International (SCS), GDR I3, Lionphant Simulation, Simulation Team and IFIP and held in cooperation with AIS Special Interest Group of Modeling and Simulation (AIS SIGMAS) and the Movimento Italiano Modellazione e Simulazione (MIMOS).
Irradiation Design for an Experimental Murine Model
International Nuclear Information System (INIS)
Ballesteros-Zebadua, P.; Moreno-Jimenez, S.; Suarez-Campos, J. E.; Celis, M. A.; Larraga-Gutierrez, J. M.; Garcia-Garduno, O. A.; Rubio-Osornio, M. C.; Custodio-Ramirez, V.; Paz, C.
2010-01-01
In radiotherapy and stereotactic radiosurgery, small animal experimental models are frequently used, since there are still a lot of unsolved questions about the biological and biochemical effects of ionizing radiation. This work presents a method for small-animal brain radiotherapy compatible with a dedicated 6MV Linac. This rodent model is focused on the research of the inflammatory effects produced by ionizing radiation in the brain. In this work comparisons between Pencil Beam and Monte Carlo techniques, were used in order to evaluate accuracy of the calculated dose using a commercial planning system. Challenges in this murine model are discussed.
Composing problem solvers for simulation experimentation: a case study on steady state estimation.
Leye, Stefan; Ewald, Roland; Uhrmacher, Adelinde M
2014-01-01
Simulation experiments involve various sub-tasks, e.g., parameter optimization, simulation execution, or output data analysis. Many algorithms can be applied to such tasks, but their performance depends on the given problem. Steady state estimation in systems biology is a typical example for this: several estimators have been proposed, each with its own (dis-)advantages. Experimenters, therefore, must choose from the available options, even though they may not be aware of the consequences. To support those users, we propose a general scheme to aggregate such algorithms to so-called synthetic problem solvers, which exploit algorithm differences to improve overall performance. Our approach subsumes various aggregation mechanisms, supports automatic configuration from training data (e.g., via ensemble learning or portfolio selection), and extends the plugin system of the open source modeling and simulation framework James II. We show the benefits of our approach by applying it to steady state estimation for cell-biological models.
Paxson, Daniel E.; Fotia, Matthew L.; Hoke, John; Schauer, Fred
2015-01-01
A quasi-two-dimensional, computational fluid dynamic (CFD) simulation of a rotating detonation engine (RDE) is described. The simulation operates in the detonation frame of reference and utilizes a relatively coarse grid such that only the essential primary flow field structure is captured. This construction and other simplifications yield rapidly converging, steady solutions. Viscous effects, and heat transfer effects are modeled using source terms. The effects of potential inlet flow reversals are modeled using boundary conditions. Results from the simulation are compared to measured data from an experimental RDE rig with a converging-diverging nozzle added. The comparison is favorable for the two operating points examined. The utility of the code as a performance optimization tool and a diagnostic tool are discussed.
Recent Advances in Simulation of Eddy Current Testing of Tubes and Experimental Validations
Reboud, C.; Prémel, D.; Lesselier, D.; Bisiaux, B.
2007-03-01
Eddy current testing (ECT) is widely used in iron and steel industry for the inspection of tubes during manufacturing. A collaboration between CEA and the Vallourec Research Center led to the development of new numerical functionalities dedicated to the simulation of ECT of non-magnetic tubes by external probes. The achievement of experimental validations led us to the integration of these models into the CIVA platform. Modeling approach and validation results are discussed here. A new numerical scheme is also proposed in order to improve the accuracy of the model.
At the biological modeling and simulation frontier.
Hunt, C Anthony; Ropella, Glen E P; Lam, Tai Ning; Tang, Jonathan; Kim, Sean H J; Engelberg, Jesse A; Sheikh-Bahaei, Shahab
2009-11-01
We provide a rationale for and describe examples of synthetic modeling and simulation (M&S) of biological systems. We explain how synthetic methods are distinct from familiar inductive methods. Synthetic M&S is a means to better understand the mechanisms that generate normal and disease-related phenomena observed in research, and how compounds of interest interact with them to alter phenomena. An objective is to build better, working hypotheses of plausible mechanisms. A synthetic model is an extant hypothesis: execution produces an observable mechanism and phenomena. Mobile objects representing compounds carry information enabling components to distinguish between them and react accordingly when different compounds are studied simultaneously. We argue that the familiar inductive approaches contribute to the general inefficiencies being experienced by pharmaceutical R&D, and that use of synthetic approaches accelerates and improves R&D decision-making and thus the drug development process. A reason is that synthetic models encourage and facilitate abductive scientific reasoning, a primary means of knowledge creation and creative cognition. When synthetic models are executed, we observe different aspects of knowledge in action from different perspectives. These models can be tuned to reflect differences in experimental conditions and individuals, making translational research more concrete while moving us closer to personalized medicine.
A physiological production model for cacao : results of model simulations
Zuidema, P.A.; Leffelaar, P.A.
2002-01-01
CASE2 is a physiological model for cocoa (Theobroma cacao L.) growth and yield. This report introduces the CAcao Simulation Engine for water-limited production in a non-technical way and presents simulation results obtained with the model.
Comparison of GEANT4 Simulations with Experimental Data for Thick Al Absorbers
International Nuclear Information System (INIS)
Yevseyeva, Olga; Assis, Joaquim de; Evseev, Ivan; Schelin, Hugo; Paschuk, Sergei; Milhoretto, Edney; Setti, Joao; Diaz, Katherin; Lopes, Ricardo; Hormaza, Joel
2009-01-01
Proton beams in medical applications deal with relatively thick targets like the human head or trunk. Therefore, relatively small differences in the total proton stopping power given, for example, by the different models provided by GEANT4 can lead to significant disagreements in the final proton energy spectra when integrated along lengthy proton trajectories. This work presents proton energy spectra obtained by GEANT4.8.2 simulations using ICRU49, Ziegler1985 and Ziegler2000 models for 19.68 MeV protons passing through a number of Al absorbers with various thicknesses. The spectra were compared with the experimental data, with TRIM/SRIM2008 and MCNPX2.4.0 simulations, and with the Payne analytical solution for the transport equation in the Fokker-Plank approximation. It is shown that the MCNPX simulations reasonably reproduce well all experimental spectra. For the relatively thin targets all the methods give practically identical results but this is not the same for the thick absorbers. It should be noted that all the spectra were measured at the proton energies significantly above 2 MeV, i.e., in the so-called 'Bethe-Bloch region'. Therefore the observed disagreements in GEANT4 results, simulated with different models, are somewhat unexpected. Further studies are necessary for better understanding and definitive conclusions.
Modeling VOC transport in simulated waste drums
International Nuclear Information System (INIS)
Liekhus, K.J.; Gresham, G.L.; Peterson, E.S.; Rae, C.; Hotz, N.J.; Connolly, M.J.
1993-06-01
A volatile organic compound (VOC) transport model has been developed to describe unsteady-state VOC permeation and diffusion within a waste drum. Model equations account for three primary mechanisms for VOC transport from a void volume within the drum. These mechanisms are VOC permeation across a polymer boundary, VOC diffusion across an opening in a volume boundary, and VOC solubilization in a polymer boundary. A series of lab-scale experiments was performed in which the VOC concentration was measured in simulated waste drums under different conditions. A lab-scale simulated waste drum consisted of a sized-down 55-gal metal drum containing a modified rigid polyethylene drum liner. Four polyethylene bags were sealed inside a large polyethylene bag, supported by a wire cage, and placed inside the drum liner. The small bags were filled with VOC-air gas mixture and the VOC concentration was measured throughout the drum over a period of time. Test variables included the type of VOC-air gas mixtures introduced into the small bags, the small bag closure type, and the presence or absence of a variable external heat source. Model results were calculated for those trials where the VOC permeability had been measured. Permeabilities for five VOCs [methylene chloride, 1,1,2-trichloro-1,2,2-trifluoroethane (Freon-113), 1,1,1-trichloroethane, carbon tetrachloride, and trichloroethylene] were measured across a polyethylene bag. Comparison of model and experimental results of VOC concentration as a function of time indicate that model accurately accounts for significant VOC transport mechanisms in a lab-scale waste drum
Stocco, Andrea; Yamasaki, Brianna L; Prat, Chantel S
2018-04-01
This article describes the data analyzed in the paper "Individual differences in the Simon effect are underpinned by differences in the competitive dynamics in the basal ganglia: An experimental verification and a computational model" (Stocco et al., 2017) [1]. The data includes behavioral results from participants performing three cognitive tasks (Probabilistic Stimulus Selection (Frank et al., 2004) [2], Simon task (Craft and Simon, 1970) [3], and Automated Operation Span (Unsworth et al., 2005) [4]), as well as simulationed traces generated by a computational neurocognitive model that accounts for individual variations in human performance across the tasks. The experimental data encompasses individual data files (in both preprocessed and native output format) as well as group-level summary files. The simulation data includes the entire model code, the results of a full-grid search of the model's parameter space, and the code used to partition the model space and parallelize the simulations. Finally, the repository includes the R scripts used to carry out the statistical analyses reported in the original paper.
Development of a Simulation Model for Swimming with Diving Fins
Directory of Open Access Journals (Sweden)
Motomu Nakashima
2018-02-01
Full Text Available The simulation model to assess the performance of diving fin was developed by extending the swimming human simulation model SWUM. A diving fin was modeled as a series of five rigid plates and connected to the human model by springs and dampers. These plates were connected to each other by virtual springs and dampers, and fin’s bending property was represented by springs and dampers as well. An actual diver’s swimming motion with fins was acquired by a motion capture experiment. In order to determine the bending property of the fin, two bending tests on land were conducted. In addition, an experiment was conducted in order to determine the fluid force coefficients in the fluid force model for the fin. Finally, using all measured and identified information, a simulation, in which the experimental situation was reproduced, was carried out. It was confirmed that the diver in the simulation propelled forward in the water successfully.
Energy Technology Data Exchange (ETDEWEB)
Skraaning, Gyrd Jr.
2004-03-15
This report is a reprint of a dr.philos. thesis written by Gyrd Skraaning Jr. The text was submitted and accepted by the Norwegian University of Science and Technology in 2003 (ISBN 82-471-5237-1). The thesis suggests a nonlinear model of the theoretical relationship between experimental control and realism, claiming that high degrees of realism and experimental control can be obtained simultaneously if the experimental methods are utilized strategically and developed further. This is in opposition to the conventional opinion that realism and experimental control are mutually excluding objectives. The thesis debates the impact of the operating task on human performance during simulator studies in HAMMLAB, and suggests how task variation can be experimentally controlled. In a within subject design, every subject is tested under all experimental conditions, and the presentation order of the conditions is counterbalanced to compensate for order effects. In realistic settings, it is essential that the experimental design imposes few artificial constrains on the research environment. At the same time, the design should be able to uncover experimental effects in situations where the number of participants is low. Within-subject design represents a reasonable compromise between these aspirations. In this respect, an alternative counterbalancing method is proposed (dis-ORDER). A theoretical analysis of the human performance concept and a discussion about performance measurement in complex operating environments, are followed by a debate on the shortcomings of traditional performance indicators. Two specialized operator performance assessment techniques are then presented and evaluated (OPAS and ORT). (Author)
International Nuclear Information System (INIS)
Skraaning, Gyrd Jr.
2004-03-01
This report is a reprint of a dr.philos. thesis written by Gyrd Skraaning Jr. The text was submitted and accepted by the Norwegian University of Science and Technology in 2003 (ISBN 82-471-5237-1). The thesis suggests a nonlinear model of the theoretical relationship between experimental control and realism, claiming that high degrees of realism and experimental control can be obtained simultaneously if the experimental methods are utilized strategically and developed further. This is in opposition to the conventional opinion that realism and experimental control are mutually excluding objectives. The thesis debates the impact of the operating task on human performance during simulator studies in HAMMLAB, and suggests how task variation can be experimentally controlled. In a within subject design, every subject is tested under all experimental conditions, and the presentation order of the conditions is counterbalanced to compensate for order effects. In realistic settings, it is essential that the experimental design imposes few artificial constrains on the research environment. At the same time, the design should be able to uncover experimental effects in situations where the number of participants is low. Within-subject design represents a reasonable compromise between these aspirations. In this respect, an alternative counterbalancing method is proposed (dis-ORDER). A theoretical analysis of the human performance concept and a discussion about performance measurement in complex operating environments, are followed by a debate on the shortcomings of traditional performance indicators. Two specialized operator performance assessment techniques are then presented and evaluated (OPAS and ORT). (Author)
Microstructural evolution during nitriding, finite element simulation and experimental assessment
Energy Technology Data Exchange (ETDEWEB)
Hassani-Gangaraj, S.M. [Politecnico di Milano, Dipartimento di Meccanica, Via La Masa, 1, 20156 Milano (Italy); Guagliano, M., E-mail: mario.guagliano@polimi.it [Politecnico di Milano, Dipartimento di Meccanica, Via La Masa, 1, 20156 Milano (Italy)
2013-04-15
A finite element simulation of nitriding is proposed in this paper, using the analogy between diffusion and heat conduction, to overcome the shortcomings of the classical internal oxidation model in predicting the kinetics of layer growth and nitrogen distribution during nitriding. To verify the model, a typical gas nitriding has been carried out on an axisymmetric specimen. Treated specimen has been characterized using optical microscopy (OM), scanning electron microscopy (SEM), micro-hardness and X-Ray diffraction (XRD) measurements. It was found that the so-called diffusion zone can be divided into two parts with different influence on the mechanical characteristics including residual stress and hardening. First layer which is a two phase region of ferritic matrix and γ′ (Fe{sub 4}N) makes further improvement with respect to the second layer which is a solid solution of nitrogen in ferrite. The formation of that two phase region, which is not predicted by classical model, can be efficiently recognized by the proposed model. It is also proved that the model has the ability to consider the geometry dependency of layer growth and formation in nitriding.
Simulation and experimental study on lithium ion battery short circuit
International Nuclear Information System (INIS)
Zhao, Rui; Liu, Jie; Gu, Junjie
2016-01-01
Highlights: • Both external and internal short circuit tests were performed on Li-ion batteries. • An electrochemical–thermal model with an additional nail site heat source is presented. • The model can accurately simulate the temperature variations of non-venting batteries. • The model is reliable in predicting the occurrence and start time of thermal runaway. • A hydrogel cooling system proves its strength in preventing battery thermal runaway. - Abstract: Safety is the first priority in lithium ion (Li-ion) battery applications. A large portion of electrical and thermal hazards caused by Li-ion battery is associated with short circuit. In this paper, both external and internal short circuit tests are conducted. Li-ion batteries and battery packs of different capacities are used. The results indicate that external short circuit is worse for smaller size batteries due to their higher internal resistances, and this type of short can be well managed by assembling fuses. In internal short circuit tests, higher chance of failure is found on larger capacity batteries. A modified electrochemical–thermal model is proposed, which incorporates an additional heat source from nail site and proves to be successful in depicting temperature changes in batteries. Specifically, the model is able to estimate the occurrence and approximate start time of thermal runaway. Furthermore, the effectiveness of a hydrogel based thermal management system in suppressing thermal abuse and preventing thermal runaway propagation is verified through the external and internal short tests on batteries and battery packs.
Experimental Simulations of Lunar Magma Ocean Crystallization: The Plot (But Not the Crust) Thickens
Draper, D. S.; Rapp, J. F.; Elardo, S. M.; Shearer, C. K., Jr.; Neal, C. R.
2016-01-01
Numerical models of differentiation of a global-scale lunar magma ocean (LMO) have raised as many questions as they have answered. Recent orbital missions and sample studies have provided new context for a large range of lithologies, from the comparatively magnesian "purest anorthosite" reported by to Si-rich domes and spinel-rich clasts with widespread areal distributions. In addition, the GRAIL mission provided strong constraints on lunar crustal density and average thickness. Can this increasingly complex geology be accounted for via the formation and evolution of the LMO? We have in recent years been conducting extensive sets of petrologic experiments designed to fully simulate LMO crystallization, which had not been attempted previously. Here we review the key results from these experiments, which show that LMO differentiation is more complex than initial models suggested. Several important features expected from LMO crystallization models have yet to be reproduced experimentally; combined modelling and experimental work by our group is ongoing.
Huntington disease: Experimental models and therapeutic perspectives
International Nuclear Information System (INIS)
Serrano Sanchez, Teresa; Blanco Lezcano, Lisette; Garcia Minet, Rocio; Alberti Amador, Esteban; Diaz Armesto, Ivan and others
2011-01-01
Huntington's disease (HD) is a degenerative dysfunction of hereditary origin. Up to date there is not, an effective treatment to the disease which having lapsed 15 or 20 years advances inexorably, in a slow form, toward the total inability or death. This paper reviews the clinical and morphological characteristics of Huntington's disease as well as the experimental models more commonly used to study this disease, having as source the articles indexed in Medline data base, published in the last 20 years. Advantages and disadvantages of all experimental models to reproduce the disease as well as the perspectives to therapeutic assay have been also considered. the consent of outline reported about the toxic models, those induced by neurotoxins such as quinolinic acid, appears to be the most appropriate to reproduce the neuropathologic characteristic of the disease, an genetic models contributing with more evidence to the knowledge of the disease etiology. Numerous treatments ameliorate clinical manifestations, but none of them has been able to stop or diminish the affectations derived from neuronal loss. At present time it is possible to reproduce, at least partially, the characteristics of the disease in experimentation animals that allow therapy evaluation in HD. from the treatment view point, the more promissory seems to be transplantation of no neuronal cells, taking into account ethical issues and factibility. On the other hand the new technology of interference RNA emerges as a potential therapeutic tool for treatment in HD, and to respond basic questions on the development of the disease.
Simulation-Based Internal Models for Safer Robots
Directory of Open Access Journals (Sweden)
Christian Blum
2018-01-01
Full Text Available In this paper, we explore the potential of mobile robots with simulation-based internal models for safety in highly dynamic environments. We propose a robot with a simulation of itself, other dynamic actors and its environment, inside itself. Operating in real time, this simulation-based internal model is able to look ahead and predict the consequences of both the robot’s own actions and those of the other dynamic actors in its vicinity. Hence, the robot continuously modifies its own actions in order to actively maintain its own safety while also achieving its goal. Inspired by the problem of how mobile robots could move quickly and safely through crowds of moving humans, we present experimental results which compare the performance of our internal simulation-based controller with a purely reactive approach as a proof-of-concept study for the practical use of simulation-based internal models.
Network Modeling and Simulation A Practical Perspective
Guizani, Mohsen; Khan, Bilal
2010-01-01
Network Modeling and Simulation is a practical guide to using modeling and simulation to solve real-life problems. The authors give a comprehensive exposition of the core concepts in modeling and simulation, and then systematically address the many practical considerations faced by developers in modeling complex large-scale systems. The authors provide examples from computer and telecommunication networks and use these to illustrate the process of mapping generic simulation concepts to domain-specific problems in different industries and disciplines. Key features: Provides the tools and strate
Dynamic Modeling of Wind Turbine Gearboxes and Experimental Validation
DEFF Research Database (Denmark)
Pedersen, Rune
Grinding corrections are often applied to gear teeth, which will alter the load distribution across the tooth. Grinding corrections will also change the load sharing between neighboring tooth pairs, and in turn the gear mesh stiffness. In this thesis, a model for calculating the gear mesh stiffness...... is presented. The model takes into account the effects of load and applied grinding corrections. The results are verified by comparing to simulated and experimental results reported in the existing literature. Using gear data loosely based on a 1 MW wind turbine gearbox, the gear mesh stiffness is expanded...
Scaled Experimental Modeling of VHTR Plenum Flows
Energy Technology Data Exchange (ETDEWEB)
ICONE 15
2007-04-01
Abstract The Very High Temperature Reactor (VHTR) is the leading candidate for the Next Generation Nuclear Power (NGNP) Project in the U.S. which has the goal of demonstrating the production of emissions free electricity and hydrogen by 2015. Various scaled heated gas and water flow facilities were investigated for modeling VHTR upper and lower plenum flows during the decay heat portion of a pressurized conduction-cooldown scenario and for modeling thermal mixing and stratification (“thermal striping”) in the lower plenum during normal operation. It was concluded, based on phenomena scaling and instrumentation and other practical considerations, that a heated water flow scale model facility is preferable to a heated gas flow facility and to unheated facilities which use fluids with ranges of density to simulate the density effect of heating. For a heated water flow lower plenum model, both the Richardson numbers and Reynolds numbers may be approximately matched for conduction-cooldown natural circulation conditions. Thermal mixing during normal operation may be simulated but at lower, but still fully turbulent, Reynolds numbers than in the prototype. Natural circulation flows in the upper plenum may also be simulated in a separate heated water flow facility that uses the same plumbing as the lower plenum model. However, Reynolds number scaling distortions will occur at matching Richardson numbers due primarily to the necessity of using a reduced number of channels connected to the plenum than in the prototype (which has approximately 11,000 core channels connected to the upper plenum) in an otherwise geometrically scaled model. Experiments conducted in either or both facilities will meet the objectives of providing benchmark data for the validation of codes proposed for NGNP designs and safety studies, as well as providing a better understanding of the complex flow phenomena in the plenums.
Experimental and simulation validation of ABHE for disinfection of Legionella in hot water systems
International Nuclear Information System (INIS)
Altorkmany, Lobna; Kharseh, Mohamad; Ljung, Anna-Lena; Staffan Lundström, T.
2017-01-01
Highlights: • ABHE system can supply a continues thermal treatment of water with saving energy. • Mathematical and experimental validation of ABHE performance are presented. • EES-based model is developed to simulate ABHE system. • Energy saving by ABHE is proved for different initial working parameters. - Abstract: The work refers to an innovative system inspired by nature that mimics the thermoregulation system that exists in animals. This method, which is called Anti Bacteria Heat Exchanger (ABHE), is proposed to achieve continuous thermal disinfection of bacteria in hot water systems with high energy efficiency. In particular, this study aims to demonstrate the opportunity to gain energy by means of recovering heat over a plate heat exchanger. Firstly, the thermodynamics of the ABHE is clarified to define the ABHE specification. Secondly, a first prototype of an ABHE is built with a specific configuration based on simplicity regarding design and construction. Thirdly, an experimental test is carried out. Finally, a computer model is built to simulate the ABHE system and the experimental data is used to validate the model. The experimental results indicate that the performance of the ABHE system is strongly dependent on the flow rate, while the supplied temperature has less effect. Experimental and simulation data show a large potential for saving energy of this thermal disinfection method by recovering heat. To exemplify, when supplying water at a flow rate of 5 kg/min and at a temperature of 50 °C, the heat recovery is about 1.5 kW while the required pumping power is 1 W. This means that the pressure drop is very small compared to the energy recovered and consequently high saving in total cost is promising.
Experimental Investigation and High Resolution Simulation of In-Situ Combustion Processes
Energy Technology Data Exchange (ETDEWEB)
Margot Gerritsen; Tony Kovscek
2008-04-30
This final technical report describes work performed for the project 'Experimental Investigation and High Resolution Numerical Simulator of In-Situ Combustion Processes', DE-FC26-03NT15405. In summary, this work improved our understanding of in-situ combustion (ISC) process physics and oil recovery. This understanding was translated into improved conceptual models and a suite of software algorithms that extended predictive capabilities. We pursued experimental, theoretical, and numerical tasks during the performance period. The specific project objectives were (i) identification, experimentally, of chemical additives/injectants that improve combustion performance and delineation of the physics of improved performance, (ii) establishment of a benchmark one-dimensional, experimental data set for verification of in-situ combustion dynamics computed by simulators, (iii) develop improved numerical methods that can be used to describe in-situ combustion more accurately, and (iv) to lay the underpinnings of a highly efficient, 3D, in-situ combustion simulator using adaptive mesh refinement techniques and parallelization. We believe that project goals were met and exceeded as discussed.
Solar power plant performance evaluation: simulation and experimental validation
International Nuclear Information System (INIS)
Natsheh, E M; Albarbar, A
2012-01-01
In this work the performance of solar power plant is evaluated based on a developed model comprise photovoltaic array, battery storage, controller and converters. The model is implemented using MATLAB/SIMULINK software package. Perturb and observe (P and O) algorithm is used for maximizing the generated power based on maximum power point tracker (MPPT) implementation. The outcome of the developed model are validated and supported by a case study carried out using operational 28.8kW grid-connected solar power plant located in central Manchester. Measurements were taken over 21 month's period; using hourly average irradiance and cell temperature. It was found that system degradation could be clearly monitored by determining the residual (the difference) between the output power predicted by the model and the actual measured power parameters. It was found that the residual exceeded the healthy threshold, 1.7kW, due to heavy snow in Manchester last winter. More important, the developed performance evaluation technique could be adopted to detect any other reasons that may degrade the performance of the P V panels such as shading and dirt. Repeatability and reliability of the developed system performance were validated during this period. Good agreement was achieved between the theoretical simulation and the real time measurement taken the online grid connected solar power plant.
Solar power plant performance evaluation: simulation and experimental validation
Natsheh, E. M.; Albarbar, A.
2012-05-01
In this work the performance of solar power plant is evaluated based on a developed model comprise photovoltaic array, battery storage, controller and converters. The model is implemented using MATLAB/SIMULINK software package. Perturb and observe (P&O) algorithm is used for maximizing the generated power based on maximum power point tracker (MPPT) implementation. The outcome of the developed model are validated and supported by a case study carried out using operational 28.8kW grid-connected solar power plant located in central Manchester. Measurements were taken over 21 month's period; using hourly average irradiance and cell temperature. It was found that system degradation could be clearly monitored by determining the residual (the difference) between the output power predicted by the model and the actual measured power parameters. It was found that the residual exceeded the healthy threshold, 1.7kW, due to heavy snow in Manchester last winter. More important, the developed performance evaluation technique could be adopted to detect any other reasons that may degrade the performance of the P V panels such as shading and dirt. Repeatability and reliability of the developed system performance were validated during this period. Good agreement was achieved between the theoretical simulation and the real time measurement taken the online grid connected solar power plant.
Modelling and simulation of a heat exchanger
Xia, Lei; Deabreu-Garcia, J. Alex; Hartley, Tom T.
1991-01-01
Two models for two different control systems are developed for a parallel heat exchanger. First by spatially lumping a heat exchanger model, a good approximate model which has a high system order is produced. Model reduction techniques are applied to these to obtain low order models that are suitable for dynamic analysis and control design. The simulation method is discussed to ensure a valid simulation result.
Dynamic modeling and simulation of a real world billiard
International Nuclear Information System (INIS)
Hartl, Alexandre E.; Miller, Bruce N.; Mazzoleni, Andre P.
2011-01-01
Gravitational billiards provide an experimentally accessible arena for testing formulations of nonlinear dynamics. We present a mathematical model that captures the essential dynamics required for describing the motion of a realistic billiard for arbitrary boundaries. Simulations of the model are applied to parabolic, wedge and hyperbolic billiards that are driven sinusoidally. Direct comparisons are made between the model's predictions and previously published experimental data. It is shown that the data can be successfully modeled with a simple set of parameters without an assumption of exotic energy dependence. -- Highlights: → We create a model of a gravitational billiard that includes rotation and dissipation. → Predictions of the model are compared with the experiments of Felt and Olafsen. → The simulations correctly predict the essential features of the experiments.
Modeling and simulation of large HVDC systems
Energy Technology Data Exchange (ETDEWEB)
Jin, H.; Sood, V.K.
1993-01-01
This paper addresses the complexity and the amount of work in preparing simulation data and in implementing various converter control schemes and the excessive simulation time involved in modelling and simulation of large HVDC systems. The Power Electronic Circuit Analysis program (PECAN) is used to address these problems and a large HVDC system with two dc links is simulated using PECAN. A benchmark HVDC system is studied to compare the simulation results with those from other packages. The simulation time and results are provided in the paper.
Experimental tests of proton spin models
International Nuclear Information System (INIS)
Ramsey, G.P.; Argonne National Lab., IL
1989-01-01
We have developed models for the spin-weighted quark and gluon distribution in a longitudinally polarized proton. The model parameters are determined from current algebra sum rules and polarized deep-inelastic scattering data. A number of different scenarios are presented for the fraction of spin carried the constituent parton distributions. A possible long-range experimental program is suggested for measuring various hard scattering processes using polarized lepton and proton beams. With the knowledge gained from these experiments, we can begin to understand the parton contributions to the proton spin. 28 refs., 5 figs
Directory of Open Access Journals (Sweden)
Andrea Stocco
2018-04-01
Full Text Available This article describes the data analyzed in the paper “Individual differences in the Simon effect are underpinned by differences in the competitive dynamics in the basal ganglia: An experimental verification and a computational model” (Stocco et al., 2017 [1]. The data includes behavioral results from participants performing three cognitive tasks (Probabilistic Stimulus Selection (Frank et al., 2004 [2], Simon task (Craft and Simon, 1970 [3], and Automated Operation Span (Unsworth et al., 2005 [4], as well as simulationed traces generated by a computational neurocognitive model that accounts for individual variations in human performance across the tasks. The experimental data encompasses individual data files (in both preprocessed and native output format as well as group-level summary files. The simulation data includes the entire model code, the results of a full-grid search of the model's parameter space, and the code used to partition the model space and parallelize the simulations. Finally, the repository includes the R scripts used to carry out the statistical analyses reported in the original paper.
Synthetic tracked aperture ultrasound imaging: design, simulation, and experimental evaluation.
Zhang, Haichong K; Cheng, Alexis; Bottenus, Nick; Guo, Xiaoyu; Trahey, Gregg E; Boctor, Emad M
2016-04-01
Ultrasonography is a widely used imaging modality to visualize anatomical structures due to its low cost and ease of use; however, it is challenging to acquire acceptable image quality in deep tissue. Synthetic aperture (SA) is a technique used to increase image resolution by synthesizing information from multiple subapertures, but the resolution improvement is limited by the physical size of the array transducer. With a large F-number, it is difficult to achieve high resolution in deep regions without extending the effective aperture size. We propose a method to extend the available aperture size for SA-called synthetic tracked aperture ultrasound (STRATUS) imaging-by sweeping an ultrasound transducer while tracking its orientation and location. Tracking information of the ultrasound probe is used to synthesize the signals received at different positions. Considering the practical implementation, we estimated the effect of tracking and ultrasound calibration error to the quality of the final beamformed image through simulation. In addition, to experimentally validate this approach, a 6 degree-of-freedom robot arm was used as a mechanical tracker to hold an ultrasound transducer and to apply in-plane lateral translational motion. Results indicate that STRATUS imaging with robotic tracking has the potential to improve ultrasound image quality.
Numerical and experimental validation of a particle Galerkin method for metal grinding simulation
Wu, C. T.; Bui, Tinh Quoc; Wu, Youcai; Luo, Tzui-Liang; Wang, Morris; Liao, Chien-Chih; Chen, Pei-Yin; Lai, Yu-Sheng
2018-03-01
In this paper, a numerical approach with an experimental validation is introduced for modelling high-speed metal grinding processes in 6061-T6 aluminum alloys. The derivation of the present numerical method starts with an establishment of a stabilized particle Galerkin approximation. A non-residual penalty term from strain smoothing is introduced as a means of stabilizing the particle Galerkin method. Additionally, second-order strain gradients are introduced to the penalized functional for the regularization of damage-induced strain localization problem. To handle the severe deformation in metal grinding simulation, an adaptive anisotropic Lagrangian kernel is employed. Finally, the formulation incorporates a bond-based failure criterion to bypass the prospective spurious damage growth issues in material failure and cutting debris simulation. A three-dimensional metal grinding problem is analyzed and compared with the experimental results to demonstrate the effectiveness and accuracy of the proposed numerical approach.
Simulation and experimental research of heat leakage of cryogenic transfer lines
Deng, B. C.; Xie, X. J.; Pan, W.; Jiang, R. X.; Li, J.; Yang, S. Q.; Li, Q.
2017-12-01
The heat leakage of cryogenic transfer lines directly influences the performance of large-scale helium refrigerator. In this paper, a thermal model of cryogenic transfer line considering numerical simulation of support coupled with MLI was established. To validate the model, test platform of cryogenic transfer lines with the merits of disassembly outer pipe and changeable easily multi-layer insulation has been built. The experimental results of heat leakage through overall length of cryogenic transfer lines, support and multi-layer insulation were obtained. The heat leakages of multi-layer insulation, a support and the overall leakage are 1.02 W/m, 0.44 W and 1.46 W/m from experimental data, respectively. The difference of heat leakage of MLI between experiment and simulation were less than 5%. The temperature distribution of support and MLI obtained in presented model in good agreement with experimental data. It is expected to reduce the overall heat leakage of cryogenic transfer lines further by optimizing structure of support based on the above thermal model and test platform in this paper.
Experimental In Vivo Models of Candidiasis
Directory of Open Access Journals (Sweden)
Esther Segal
2018-02-01
Full Text Available Candidiasis is a multifaceted fungal disease including mucosal-cutaneous, visceral, and disseminated infections caused by yeast species of the genus Candida. Candida infections are among the most common human mycoses. Candida species are the third to fourth most common isolates from bloodstream infections in neutropenic or immunocompromised hospitalized patients. The mucosal-cutaneous forms—particularly vaginal infections—have a high prevalence. Vaginitis caused by Candida species is the second most common vaginal infection. Hence, candidiasis is a major subject for research, including experimental in vivo models to study pathogenesis, prevention, or therapy of the disease. The following review article will focus on various experimental in vivo models in different laboratory animals, such as mammals (mice, rats, rabbits, the fruit fly–Drosophila melanogaster, the larvae of the moth Galleria mellonella, or the free-living nematode Caenorhabditis elegans. The review will describe the induction of the different clinical forms of candidiasis in the various models and the validity of such models in mimicking the human clinical situations. The use of such models for the assessment of antifungal drugs, evaluation of potential vaccines to protect before candidiasis, exploration of Candida virulence factors, and comparison of pathogenicity of different Candida species will be included in the review. All of the above will be reported as based on published studies of numerous investigators as well as on the research of the author and his group.
Bloxham, Harry A; Velichko, Alexander; Wilcox, Paul David
2016-12-01
Ultrasonic nondestructive testing inspections using phased arrays are performed on a wide range of components and materials. All real inspections suffer, to varying extents, from coherent noise, including image artifacts and speckle caused by complex geometries and grain scatter, respectively. By its nature, this noise is not reduced by averaging; however, it degrades the signal-to-noise ratio of defects and ultimately limits their detectability. When evaluating the effectiveness of an inspection, a large pool of data from samples containing a range of different defects are important to estimate the probability of detection of defects and to help characterize them. For a given inspection, coherent noise is easy to measure experimentally but hard to model realistically. Conversely, the ultrasonic response of defects can be simulated relatively easily. This paper proposes a novel method of simulating realistic array data by combining noise-free simulations of defect responses with coherent noise taken from experimental data. This removes the need for costly physical samples with known defects to be made and allows for large data sets to be created easily.
Experimental modeling of eddy current inspection capabilities
International Nuclear Information System (INIS)
Junker, W.R.; Clark, W.G.
1984-01-01
This chapter examines the experimental modeling of eddy current inspection capabilities based upon the use of liquid mercury samples designed to represent metal components containing discontinuities. A brief summary of past work with mercury modeling and a detailed discussion of recent experiments designed to further evaluate the technique are presented. The main disadvantages of the mercury modeling concept are that mercury is toxic and must be handled carefully, liquid mercury can only be used to represent nonferromagnetic materials, and wetting and meniscus problems can distort the effective size of artificial discontinuities. Artificial discontinuities placed in a liquid mercury sample can be used to represent discontinuities in solid metallic structures. Discontinuity size and type cannot be characterized from phase angle and signal amplitude data developed with a surface scanning, pancake-type eddy current probe. It is concluded that the mercury model approach can greatly enhance the overall understanding and applicability of eddy current inspection techniques
Genetic fuzzy system modeling and simulation of vascular behaviour
DEFF Research Database (Denmark)
Tang, Jiaowei; Boonen, Harrie C.M.
Background: The purpose of our project is to identify the rule sets and their interaction within the framework of cardiovascular function. By an iterative process of computational simulation and experimental work, we strive to mimic the physiological basis for cardiovascular adaptive changes in c...... the pressure change of different blood vessels. Conclusion: Genetic fuzzy system is one of potential modeling methods in modeling and simulation of vascular behavior.......Background: The purpose of our project is to identify the rule sets and their interaction within the framework of cardiovascular function. By an iterative process of computational simulation and experimental work, we strive to mimic the physiological basis for cardiovascular adaptive changes...... in cardiovascular disease and ultimately improve pharmacotherapy. For this purpose, novel computational approaches incorporating adaptive properties, auto-regulatory control and rule sets will be assessed, properties that are commonly lacking in deterministic models based on differential equations. We hypothesize...
Experimental and modelling results of a parallel-plate based active magnetic regenerator
DEFF Research Database (Denmark)
Tura, A.; Nielsen, Kaspar Kirstein; Rowe, A.
2012-01-01
The performance of a permanent magnet magnetic refrigerator (PMMR) using gadolinium parallel plates is described. The configuration and operating parameters are described in detail. Experimental results are compared to simulations using an established twodimensional model of an active magnetic...
Endometriose: modelo experimental em ratas Endometriosis: experimental model in rats
Directory of Open Access Journals (Sweden)
Eduardo Schor
1999-06-01
Full Text Available Objetivo: divulgar a metodologia da indução de endometriose experimental em animais de laboratório. Método: utilizamos ratas albinas, virgens, adultas de aproximadamente três meses de idade, que foram inicialmente anestesiadas pelo éter etílico. Aberta a cavidade abdominal, identificamos os cornos uterinos e retiramos um fragmento de aproximadamente 4 cm do corno uterino direito. Esse fragmento foi mergulhado em solução fisiológica e sob lupa estereoscópica foi separado o endométrio do miométrio e feitos retângulos de aproximadamente 4 por 5 mm. Esses foram fixados por meio de fio de sutura, sobre vasos sangüíneos visíveis a olho nu, na parede lateral do abdômen, tomando-se sempre o cuidado de manter a porção do endométrio livre voltada para a luz da cavidade abdominal. Após 21 dias os animais foram novamente operados para verificarmos o tamanho dos implantes e para retirada do endométrio ectópico para análise histológica. Resultados: macroscopicamente observamos crescimento significativo dos implantes endometriais. Ao exame microscópico pudemos observar a presença de epitélio glandular e estroma semelhantes ao do endométrio tópico. Conclusões: o modelo utilizado reproduz a doença, em ratas, sendo método auxiliar de valia para estudar esta afecção, principalmente a ação de medicamentos sobre esses implantes.Purpose: to demonstrate the experimental endometriosis induction in animals. Method: we used adult female Wistar rats weighing 200 - 250 g anesthetized with ethyl ether to open the abdominal cavity. After identifying the uterine horns, we removed an approximately 4 cm fragment from the right uterine horn. This fragment was placed in physiological saline and, with the aid of a stereoscopic magnifying glass, the endometrium was separated from the myometrium and cut into rectangles of approximately 4 x 5 mm. These rectangles were fastened to the lateral abdominal wall near great blood vessels, taking care
International Nuclear Information System (INIS)
Wang Zhou; Luo Rui; Yang Xianyong; Liang Taofeng
1999-01-01
In a pool fast reactor, the roof structure is penetrated by a number of pumps and heat exchanger units to form some annular spaces with various sizes. The natural convection of argon gas happens in the pool sky and the small annular gaps between those components and the roof containment due to thermosiphonic effects. The natural convection is studied experimentally and numerically to predict the temperature distributions inside the annular space and its surrounding structure. Numerical simulation is performed by using LVEL turbulence model and extending computational domain to the entire pool sky. The predicted results are in fair agreement with the experimental data. In comparison with commonly used k-ε model, LVEL model has better accuracy for the turbulent flow in a gap space
Systematic integration of experimental data and models in systems biology.
Li, Peter; Dada, Joseph O; Jameson, Daniel; Spasic, Irena; Swainston, Neil; Carroll, Kathleen; Dunn, Warwick; Khan, Farid; Malys, Naglis; Messiha, Hanan L; Simeonidis, Evangelos; Weichart, Dieter; Winder, Catherine; Wishart, Jill; Broomhead, David S; Goble, Carole A; Gaskell, Simon J; Kell, Douglas B; Westerhoff, Hans V; Mendes, Pedro; Paton, Norman W
2010-11-29
The behaviour of biological systems can be deduced from their mathematical models. However, multiple sources of data in diverse forms are required in the construction of a model in order to define its components and their biochemical reactions, and corresponding parameters. Automating the assembly and use of systems biology models is dependent upon data integration processes involving the interoperation of data and analytical resources. Taverna workflows have been developed for the automated assembly of quantitative parameterised metabolic networks in the Systems Biology Markup Language (SBML). A SBML model is built in a systematic fashion by the workflows which starts with the construction of a qualitative network using data from a MIRIAM-compliant genome-scale model of yeast metabolism. This is followed by parameterisation of the SBML model with experimental data from two repositories, the SABIO-RK enzyme kinetics database and a database of quantitative experimental results. The models are then calibrated and simulated in workflows that call out to COPASIWS, the web service interface to the COPASI software application for analysing biochemical networks. These systems biology workflows were evaluated for their ability to construct a parameterised model of yeast glycolysis. Distributed information about metabolic reactions that have been described to MIRIAM standards enables the automated assembly of quantitative systems biology models of metabolic networks based on user-defined criteria. Such data integration processes can be implemented as Taverna workflows to provide a rapid overview of the components and their relationships within a biochemical system.
International Nuclear Information System (INIS)
Evans, T.E.; Leonard, A.W.; West, W.P.; Finkenthal, D.F.; Fenstermacher, M.E.; Porter, G.D.
1998-08-01
Experimentally measured carbon line emissions and total radiated power distributions from the DIII-D divertor and Scrape-Off Layer (SOL) are compared to those calculated with the Monte Carlo Impurity (MCI) model. A UEDGE background plasma is used in MCI with the Roth and Garcia-Rosales (RG-R) chemical sputtering model and/or one of six physical sputtering models. While results from these simulations do not reproduce all of the features seen in the experimentally measured radiation patterns, the total radiated power calculated in MCI is in relatively good agreement with that measured by the DIII-D bolometric system when the Smith78 physical sputtering model is coupled to RG-R chemical sputtering in an unaltered UEDGE plasma. Alternatively, MCI simulations done with UEDGE background ion temperatures along the divertor target plates adjusted to better match those measured in the experiment resulted in three physical sputtering models which when coupled to the RG-R model gave a total radiated power that was within 10% of measured value
Modeling, simulation, and experiments of coating growth on nanofibers
International Nuclear Information System (INIS)
Clemons, C. B.; Hamrick, P.; Heminger, J.; Kreider, K. L.; Young, G. W.; Buldum, A.; Evans, E.; Zhang, G.
2008-01-01
This work is a comparison of modeling and simulation results with experiments for an integrated experimental/modeling investigation of a procedure to coat nanofibers and core-clad nanostructures with thin film materials using plasma enhanced physical vapor deposition. In the experimental effort, electrospun polymer nanofibers are coated with metallic materials under different operating conditions to observe changes in the coating morphology. The modeling effort focuses on linking simple models at the reactor level, nanofiber level and atomic level to form a comprehensive model. The comprehensive model leads to the definition of an evolution equation for the coating free surface around an isolated nanofiber. This evolution equation was previously derived and solved under conditions of a nearly circular coating, with a concentration field that was only radially dependent and that was independent of the location of the coating free surface. These assumptions permitted the development of analytical expressions for the concentration field. The present work does not impose the above-mentioned conditions and considers numerical simulations of the concentration field that couple with level set simulations of the evolution equation for the coating free surface. Further, the cases of coating an isolated fiber as well as a multiple fiber mat are considered. Simulation results are compared with experimental results as the reactor pressure and power, as well as the nanofiber mat porosity, are varied
Materials for the nuclear - Modelling and simulation of structure materials
International Nuclear Information System (INIS)
Berthoud, Georges; Ducros, Gerard; Feron, Damien; Guerin, Yannick; Latge, Christian; Limoge, Yves; Santarini, Gerard; Seiler, Jean-Marie; Vernaz, Etienne; Cappelaere, Chantal; Andrieux, Catherine; Athenes, Manuel; Baldinozzi, Guido; Bechade, Jean-Luc; Bonin, Bernard; Boutard, Jean-Louis; Brechet, Yves; Bruneval, Fabien; Carassou, Sebastien; Castelier, Etienne; Chartier, Alain; Clouet, Emmanuel; Marinica, Mihai-Cosmin; Crocombette, Jean-Paul; Dupuy, Laurent; Forget, Pierre; Fu, Chu Chun; Garnier, Jerome; Gelebart, Lionel; Henry, Jean; Jourdan, Thomas; Luneville, Laurence; Marini, Bernard; Meslin, Estelle; Nastar, Maylise; Onimus, Fabien; Poussard, Christophe; Proville, Laurent; Ribis, Joel; Robertson, Christian; Rodney, David; Roma, Guido; Sauzay, Maxime; Simeone, David; Soisson, Frederic; Tanguy, Benoit; Toffolon-Masclet, Caroline; Trocellier, Patrick; Van Brutzel, Laurent; Ventelon, Usa; Vincent, Ludovic; Willaime, Francois; Yvon, Pascal; Behar, Christophe; Provitina, Olivier; Lecomte, Michael; Forestier, Alain; Bender, Alexandra; Parisot, Jean-Francois; Finot, Pierre
2016-01-01
This collective publication proposes presentations of scientific approaches implemented to model and simulate the behaviour of materials submitted to irradiation, of associated experimental methods, and of some recent important results. After an introduction presenting the various materials used in different types of nuclear reactors (PWR, etc.), the effects of irradiation at the macroscopic or at the atomic scale, and the multi-scale (time and space) approach to the modelling of these materials, a chapter proposes an overview of modelling tools: multi-scale approach, electronic calculations for condensed matter, inter-atomic potentials, molecular dynamics simulation, thermodynamic and medium force potentials, phase diagrams, simulation of primary damages in reactor materials, kinetic models, dislocation dynamics, production of microstructures for simulation, crystalline visco-plasticity, homogenization methods in continuum mechanics, local approach and probabilistic approach in material fracture. The next part presents tools for experimental validation: tools for microscopic characterization or for mechanical characterization, experimental reactors and tests in atomic pile, tools for irradiation by charged particles. The next chapters presents different examples of thermodynamic and kinetic modelling in the case of various alloys (zirconium alloys, iron-chromium alloys, silicon carbide, austenitic alloys), of plasticity and failure modelling
Models for Experimental High Density Housing
Bradecki, Tomasz; Swoboda, Julia; Nowak, Katarzyna; Dziechciarz, Klaudia
2017-10-01
The article presents the effects of research on models of high density housing. The authors present urban projects for experimental high density housing estates. The design was based on research performed on 38 examples of similar housing in Poland that have been built after 2003. Some of the case studies show extreme density and that inspired the researchers to test individual virtual solutions that would answer the question: How far can we push the limits? The experimental housing projects show strengths and weaknesses of design driven only by such indexes as FAR (floor attenuation ratio - housing density) and DPH (dwellings per hectare). Although such projects are implemented, the authors believe that there are reasons for limits since high index values may be in contradiction to the optimum character of housing environment. Virtual models on virtual plots presented by the authors were oriented toward maximising the DPH index and DAI (dwellings area index) which is very often the main driver for developers. The authors also raise the question of sustainability of such solutions. The research was carried out in the URBAN model research group (Gliwice, Poland) that consists of academic researchers and architecture students. The models reflect architectural and urban regulations that are valid in Poland. Conclusions might be helpful for urban planners, urban designers, developers, architects and architecture students.
Modeling and Simulation of Low Voltage Arcs
Ghezzi, L.; Balestrero, A.
2010-01-01
Modeling and Simulation of Low Voltage Arcs is an attempt to improve the physical understanding, mathematical modeling and numerical simulation of the electric arcs that are found during current interruptions in low voltage circuit breakers. An empirical description is gained by refined electrical
Experimental data and dose-response models
International Nuclear Information System (INIS)
Ullrich, R.L.
1985-01-01
Dose-response relationships for radiation carcinogenesis have been of interest to biologists, modelers, and statisticians for many years. Despite his interest there are few instances in which there are sufficient experimental data to allow the fitting of various dose-response models. In those experimental systems for which data are available the dose-response curves for tumor induction for the various systems cannot be described by a single model. Dose-response models which have been observed following acute exposures to gamma rays include threshold, quadratic, and linear models. Data on sex, age, and environmental influences of dose suggest a strong role of host factors on the dose response. With decreasing dose rate the effectiveness of gamma ray irradiation tends to decrease in essentially every instance. In those cases in which the high dose rate dose response could be described by a quadratic model, the effect of dose rate is consistent with predictions based on radiation effects on the induction of initial events. Whether the underlying reasons for the observed dose-rate effect is a result of effects on the induction of initial events or is due to effects on the subsequent steps in the carcinogenic process is unknown. Information on the dose response for tumor induction for high LET (linear energy transfer) radiations such as neutrons is even more limited. The observed dose and dose rate data for tumor induction following neutron exposure are complex and do not appear to be consistent with predictions based on models for the induction of initial events
Simulation model for electron irradiated IGZO thin film transistors
Dayananda, G. K.; Shantharama Rai, C.; Jayarama, A.; Kim, Hyun Jae
2018-02-01
An efficient drain current simulation model for the electron irradiation effect on the electrical parameters of amorphous In-Ga-Zn-O (IGZO) thin-film transistors is developed. The model is developed based on the specifications such as gate capacitance, channel length, channel width, flat band voltage etc. Electrical parameters of un-irradiated IGZO samples were simulated and compared with the experimental parameters and 1 kGy electron irradiated parameters. The effect of electron irradiation on the IGZO sample was analysed by developing a mathematical model.
Surface physics theoretical models and experimental methods
Mamonova, Marina V; Prudnikova, I A
2016-01-01
The demands of production, such as thin films in microelectronics, rely on consideration of factors influencing the interaction of dissimilar materials that make contact with their surfaces. Bond formation between surface layers of dissimilar condensed solids-termed adhesion-depends on the nature of the contacting bodies. Thus, it is necessary to determine the characteristics of adhesion interaction of different materials from both applied and fundamental perspectives of surface phenomena. Given the difficulty in obtaining reliable experimental values of the adhesion strength of coatings, the theoretical approach to determining adhesion characteristics becomes more important. Surface Physics: Theoretical Models and Experimental Methods presents straightforward and efficient approaches and methods developed by the authors that enable the calculation of surface and adhesion characteristics for a wide range of materials: metals, alloys, semiconductors, and complex compounds. The authors compare results from the ...
Accurate lithography simulation model based on convolutional neural networks
Watanabe, Yuki; Kimura, Taiki; Matsunawa, Tetsuaki; Nojima, Shigeki
2017-07-01
Lithography simulation is an essential technique for today's semiconductor manufacturing process. In order to calculate an entire chip in realistic time, compact resist model is commonly used. The model is established for faster calculation. To have accurate compact resist model, it is necessary to fix a complicated non-linear model function. However, it is difficult to decide an appropriate function manually because there are many options. This paper proposes a new compact resist model using CNN (Convolutional Neural Networks) which is one of deep learning techniques. CNN model makes it possible to determine an appropriate model function and achieve accurate simulation. Experimental results show CNN model can reduce CD prediction errors by 70% compared with the conventional model.
Directory of Open Access Journals (Sweden)
Lizal Frantisek
2016-01-01
Full Text Available Correct definition of boundary conditions is crucial for the appropriate simulation of a flow. It is a common practice that simulation of sufficiently long upstream entrance section is performed instead of experimental investigation of the actual conditions at the boundary of the examined area, in the case that the measurement is either impossible or extremely demanding. We focused on the case of a benchmark channel with ventilation outlet, which models a regular automotive ventilation system. At first, measurements of air velocity and turbulence intensity were performed at the boundary of the examined area, i.e. in the rectangular channel 272.5 mm upstream the ventilation outlet. Then, the experimentally acquired results were compared with results obtained by numerical simulation of further upstream entrance section defined according to generally approved theoretical suggestions. The comparison showed that despite the simple geometry and general agreement of average axial velocity, certain difference was found in the shape of the velocity profile. The difference was attributed to the simplifications of the numerical model and the isotropic turbulence assumption of the used turbulence model. The appropriate recommendations were stated for the future work.
COMPARISON OF RF CAVITY TRANSPORT MODELS FOR BBU SIMULATIONS
Energy Technology Data Exchange (ETDEWEB)
Ilkyoung Shin,Byung Yunn,Todd Satogata,Shahid Ahmed
2011-03-01
The transverse focusing effect in RF cavities plays a considerable role in beam dynamics for low-energy beamline sections and can contribute to beam breakup (BBU) instability. The purpose of this analysis is to examine RF cavity models in simulation codes which will be used for BBU experiments at Jefferson Lab and improve BBU simulation results. We review two RF cavity models in the simulation codes elegant and TDBBU (a BBU simulation code developed at Jefferson Lab). elegant can include the Rosenzweig-Serafini (R-S) model for the RF focusing effect. Whereas TDBBU uses a model from the code TRANSPORT which considers the adiabatic damping effect, but not the RF focusing effect. Quantitative comparisons are discussed for the CEBAF beamline. We also compare the R-S model with the results from numerical simulations for a CEBAF-type 5-cell superconducting cavity to validate the use of the R-S model as an improved low-energy RF cavity transport model in TDBBU. We have implemented the R-S model in TDBBU. It will improve BBU simulation results to be more matched with analytic calculations and experimental results.
Comparison Of RF Cavity Transport Models For BBU Simulations
International Nuclear Information System (INIS)
Shin, Ilkyoung; Yunn, Byung; Satogata, Todd; Ahmed, Shahid
2011-01-01
The transverse focusing effect in RF cavities plays a considerable role in beam dynamics for low-energy beamline sections and can contribute to beam breakup (BBU) instability. The purpose of this analysis is to examine RF cavity models in simulation codes which will be used for BBU experiments at Jefferson Lab and improve BBU simulation results. We review two RF cavity models in the simulation codes elegant and TDBBU (a BBU simulation code developed at Jefferson Lab). elegant can include the Rosenzweig-Serafini (R-S) model for the RF focusing effect. Whereas TDBBU uses a model from the code TRANSPORT which considers the adiabatic damping effect, but not the RF focusing effect. Quantitative comparisons are discussed for the CEBAF beamline. We also compare the R-S model with the results from numerical simulations for a CEBAF-type 5-cell superconducting cavity to validate the use of the R-S model as an improved low-energy RF cavity transport model in TDBBU. We have implemented the R-S model in TDBBU. It will improve BBU simulation results to be more matched with analytic calculations and experimental results.
Beyond Modeling: All-Atom Olfactory Receptor Model Simulations
Directory of Open Access Journals (Sweden)
Peter C Lai
2012-05-01
Full Text Available Olfactory receptors (ORs are a type of GTP-binding protein-coupled receptor (GPCR. These receptors are responsible for mediating the sense of smell through their interaction with odor ligands. OR-odorant interactions marks the first step in the process that leads to olfaction. Computational studies on model OR structures can validate experimental functional studies as well as generate focused and novel hypotheses for further bench investigation by providing a view of these interactions at the molecular level. Here we have shown the specific advantages of simulating the dynamic environment that is associated with OR-odorant interactions. We present a rigorous methodology that ranges from the creation of a computationally-derived model of an olfactory receptor to simulating the interactions between an OR and an odorant molecule. Given the ubiquitous occurrence of GPCRs in the membranes of cells, we anticipate that our OR-developed methodology will serve as a model for the computational structural biology of all GPCRs.
International Nuclear Information System (INIS)
Bouchet, M I De Barros; Matta, C; Le-Mogne, Th; Martin, J Michel; Zhang, Q; III, W Goddard; Kano, M; Mabuchi, Y; Ye, J
2007-01-01
We report a unique tribological system that produces superlubricity under boundary lubrication conditions with extremely little wear. This system is a thin coating of hydrogen-free amorphous Diamond-Like-Carbon (denoted as ta-C) at 353 K in a ta-C/ta-C friction pair lubricated with pure glycerol. To understand the mechanism of friction vanishing we performed ToF-SIMS experiments using deuterated glycerol and 13 C glycerol. This was complemented by first-principles-based computer simulations using the ReaxFF reactive force field to create an atomistic model of ta-C. These simulations show that DLC with the experimental density of 3.24 g/cc leads to an atomistic structure consisting of a 3D percolating network of tetrahedral (sp 3 ) carbons accounting for 71.5% of the total, in excellent agreement with the 70% deduced from our Auger spectroscopy and XANES experiments. The simulations show that the remaining carbons (with sp 2 and sp 1 character) attach in short chains of length 1 to 7. In sliding simulations including glycerol molecules, the surface atoms react readily to form a very smooth carbon surface containing OH-terminated groups. This agrees with our SIMS experiments. The simulations find that the OH atoms are mostly bound to surface sp 1 atoms leading to very flexible elastic response to sliding. Both simulations and experiments suggest that the origin of the superlubricity arises from the formation of this OH-terminated surface
International Nuclear Information System (INIS)
Chaparian, A.; Oghabian, M. A.; Changizi, V.
2009-01-01
Recently, it has been indicated that X-ray coherent scatter from biological tissues can be used to access signature of tissue. Some scientists are interested in studying this effect to get early detection of breast cancer. Since experimental methods for optimization are time consuming and expensive, some scientists suggest using simulation. Monte Carlo codes are the best option for radiation simulation: however, one permanent defect with Monte Carlo codes has been the lack of a sufficient physical model for coherent (Rayleigh) scattering, including molecular interference effects. Materials and Methods: It was decided to obtain molecular interference functions of coherent X-ray scattering for normal breast tissues by combination of modeling and experimental methods. A Monte Carlo simulation program was written to simulate the angular distribution of scattered photons for the normal breast tissue samples. Moreover, experimental diffraction patterns of these tissues were measured by means of energy dispersive X-ray diffraction method. The simulation and experimental data were used to obtain a tabulation of molecular interference functions for breast tissues. Results: With this study a tabulation of molecular interference functions for normal breast tissues Was prepared to facilitate the simulation diffraction patterns of the tissues without any experimental. Conclusion: The method may lead to design new systems for early detection of breast cancer.
Experimental and numerical simulation of thermomechanical phenomena during a TIG welding process
International Nuclear Information System (INIS)
Depradeux, L.; Julien, J.F.
2004-01-01
In this study, a parallel experimental and numerical simulation of phenomena that take place in the Heat Affected Zone (HAZ) during TIG welding on 316L stainless steel is presented. The aim of this study is to predict by numerical simulation residual stresses and distortions generated by the welding process. For the experiment, a very simple geometry with reduced dimensions is considered: the specimens are disks, made of 316L. The discs are heated in the central zone in order to reproduce thermo-mechanical cycles that take place in the HAZ during a TIG welding process. During and after thermal cycle, a large quantity of measurement is provided, and allows to compare the results of different numerical models used in the simulations. The comparative thermal and mechanical analysis allows to assess the general ability of the numerical models to describe the structural behavior. The importance of the heat input rate and material characteristics is also investigated. When a melted zone is created, the thermal simulation reproduce well the temperature field in the upper face of the disk, but the size of the weld pool is not correctly rated, as fluid flows are not taken into account. Despite this fact, the general structural behavior is well represented by simulation
Whole-building Hygrothermal Simulation Model
DEFF Research Database (Denmark)
Rode, Carsten; Grau, Karl
2003-01-01
An existing integrated simulation tool for dynamic thermal simulation of building was extended with a transient model for moisture release and uptake in building materials. Validation of the new model was begun with comparison against measurements in an outdoor test cell furnished with single...... materials. Almost quasi-steady, cyclic experiments were used to compare the indoor humidity variation and the numerical results of the integrated simulation tool with the new moisture model. Except for the case with chipboard as furnishing, the predictions of indoor humidity with the detailed model were...
Superficial tension: experimental model with simple materials
Directory of Open Access Journals (Sweden)
Tintori Ferreira, María Alejandra
2012-09-01
Full Text Available In this work appears a didactic offer based on an experimental activity using materials of very low cost, orientated to achieving that the student understand and interpret the phenomenon of superficial tension together with the importance of the modeling in sciences. It has as principal aim of education bring the student over to the mechanics of the static fluids and the intermolecular forces, combining scientific contents with questions near to the student what provides an additional motivation to the reflection of the scientific investigation.
A model for plasma discharges simulation in Tokamak devices
International Nuclear Information System (INIS)
Fonseca, Antonio M.M.; Silva, Ruy P. da; Galvao, Ricardo M.O.; Kusnetzov, Yuri; Nascimento, I.C.; Cuevas, Nelson
2001-01-01
In this work, a 'zero-dimensional' model for simulation of discharges in Tokamak machine is presented. The model allows the calculation of the time profiles of important parameters of the discharge. The model was applied to the TCABR Tokamak to study the influence of parameters and physical processes during the discharges. Basically it is constituted of five differential equations: two related to the primary and secondary circuits of the ohmic heating transformer and the other three conservation equations of energy, charge and neutral particles. From the physical model, a computer program has been built with the objective of obtaining the time profiles of plasma current, the current in the primary of the ohmic heating transformer, the electronic temperature, the electronic density and the neutral particle density. It was also possible, with the model, to simulate the effects of gas puffing during the shot. The results of the simulation were compared with the experimental results obtained in the TCABR Tokamak, using hydrogen gas
Simulation modeling for the health care manager.
Kennedy, Michael H
2009-01-01
This article addresses the use of simulation software to solve administrative problems faced by health care managers. Spreadsheet add-ins, process simulation software, and discrete event simulation software are available at a range of costs and complexity. All use the Monte Carlo method to realistically integrate probability distributions into models of the health care environment. Problems typically addressed by health care simulation modeling are facility planning, resource allocation, staffing, patient flow and wait time, routing and transportation, supply chain management, and process improvement.
Protein Simulation Data in the Relational Model.
Simms, Andrew M; Daggett, Valerie
2012-10-01
High performance computing is leading to unprecedented volumes of data. Relational databases offer a robust and scalable model for storing and analyzing scientific data. However, these features do not come without a cost-significant design effort is required to build a functional and efficient repository. Modeling protein simulation data in a relational database presents several challenges: the data captured from individual simulations are large, multi-dimensional, and must integrate with both simulation software and external data sites. Here we present the dimensional design and relational implementation of a comprehensive data warehouse for storing and analyzing molecular dynamics simulations using SQL Server.
Modeling and simulation of blood collection systems.
Alfonso, Edgar; Xie, Xiaolan; Augusto, Vincent; Garraud, Olivier
2012-03-01
This paper addresses the modeling and simulation of blood collection systems in France for both fixed site and mobile blood collection with walk in whole blood donors and scheduled plasma and platelet donors. Petri net models are first proposed to precisely describe different blood collection processes, donor behaviors, their material/human resource requirements and relevant regulations. Petri net models are then enriched with quantitative modeling of donor arrivals, donor behaviors, activity times and resource capacity. Relevant performance indicators are defined. The resulting simulation models can be straightforwardly implemented with any simulation language. Numerical experiments are performed to show how the simulation models can be used to select, for different walk in donor arrival patterns, appropriate human resource planning and donor appointment strategies.
Numerical Simulation of Hydrogen Combustion: Global Reaction Model and Validation
Energy Technology Data Exchange (ETDEWEB)
Zhang, Yun [School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an (China); Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY (United States); Liu, Yinhe, E-mail: yinheliu@mail.xjtu.edu.cn [School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an (China)
2017-11-20
Due to the complexity of modeling the combustion process in nuclear power plants, the global mechanisms are preferred for numerical simulation. To quickly perform the highly resolved simulations with limited processing resources of large-scale hydrogen combustion, a method based on thermal theory was developed to obtain kinetic parameters of global reaction mechanism of hydrogen–air combustion in a wide range. The calculated kinetic parameters at lower hydrogen concentration (C{sub hydrogen} < 20%) were validated against the results obtained from experimental measurements in a container and combustion test facility. In addition, the numerical data by the global mechanism (C{sub hydrogen} > 20%) were compared with the results by detailed mechanism. Good agreement between the model prediction and the experimental data was achieved, and the comparison between simulation results by the detailed mechanism and the global reaction mechanism show that the present calculated global mechanism has excellent predictable capabilities for a wide range of hydrogen–air mixtures.
Numerical Simulation of Hydrogen Combustion: Global Reaction Model and Validation
International Nuclear Information System (INIS)
Zhang, Yun; Liu, Yinhe
2017-01-01
Due to the complexity of modeling the combustion process in nuclear power plants, the global mechanisms are preferred for numerical simulation. To quickly perform the highly resolved simulations with limited processing resources of large-scale hydrogen combustion, a method based on thermal theory was developed to obtain kinetic parameters of global reaction mechanism of hydrogen–air combustion in a wide range. The calculated kinetic parameters at lower hydrogen concentration (C hydrogen < 20%) were validated against the results obtained from experimental measurements in a container and combustion test facility. In addition, the numerical data by the global mechanism (C hydrogen > 20%) were compared with the results by detailed mechanism. Good agreement between the model prediction and the experimental data was achieved, and the comparison between simulation results by the detailed mechanism and the global reaction mechanism show that the present calculated global mechanism has excellent predictable capabilities for a wide range of hydrogen–air mixtures.
CFD simulation and experimental validation of a GM type double inlet pulse tube refrigerator
Banjare, Y. P.; Sahoo, R. K.; Sarangi, S. K.
2010-04-01
Pulse tube refrigerator has the advantages of long life and low vibration over the conventional cryocoolers, such as GM and stirling coolers because of the absence of moving parts in low temperature. This paper performs a three-dimensional computational fluid dynamic (CFD) simulation of a GM type double inlet pulse tube refrigerator (DIPTR) vertically aligned, operating under a variety of thermal boundary conditions. A commercial computational fluid dynamics (CFD) software package, Fluent 6.1 is used to model the oscillating flow inside a pulse tube refrigerator. The simulation represents fully coupled systems operating in steady-periodic mode. The externally imposed boundary conditions are sinusoidal pressure inlet by user defined function at one end of the tube and constant temperature or heat flux boundaries at the external walls of the cold-end heat exchangers. The experimental method to evaluate the optimum parameters of DIPTR is difficult. On the other hand, developing a computer code for CFD analysis is equally complex. The objectives of the present investigations are to ascertain the suitability of CFD based commercial package, Fluent for study of energy and fluid flow in DIPTR and to validate the CFD simulation results with available experimental data. The general results, such as the cool down behaviours of the system, phase relation between mass flow rate and pressure at cold end, the temperature profile along the wall of the cooler and refrigeration load are presented for different boundary conditions of the system. The results confirm that CFD based Fluent simulations are capable of elucidating complex periodic processes in DIPTR. The results also show that there is an excellent agreement between CFD simulation results and experimental results.
Modeling and Simulation of Matrix Converter
DEFF Research Database (Denmark)
Liu, Fu-rong; Klumpner, Christian; Blaabjerg, Frede
2005-01-01
This paper discusses the modeling and simulation of matrix converter. Two models of matrix converter are presented: one is based on indirect space vector modulation and the other is based on power balance equation. The basis of these two models is• given and the process on modeling is introduced...
Modelling toolkit for simulation of maglev devices
Peña-Roche, J.; Badía-Majós, A.
2017-01-01
A stand-alone App1 has been developed, focused on obtaining information about relevant engineering properties of magnetic levitation systems. Our modelling toolkit provides real time simulations of 2D magneto-mechanical quantities for superconductor (SC)/permanent magnet structures. The source code is open and may be customised for a variety of configurations. Ultimately, it relies on the variational statement of the critical state model for the superconducting component and has been verified against experimental data for YBaCuO/NdFeB assemblies. On a quantitative basis, the values of the arising forces, induced superconducting currents, as well as a plot of the magnetic field lines are displayed upon selection of an arbitrary trajectory of the magnet in the vicinity of the SC. The stability issues related to the cooling process, as well as the maximum attainable forces for a given material and geometry are immediately observed. Due to the complexity of the problem, a strategy based on cluster computing, database compression, and real-time post-processing on the device has been implemented.
Energy Technology Data Exchange (ETDEWEB)
Munoz-Cobo, J.L. [Univ. Politecnica de Valencia, Inst. de Ingenieria Energetica, Valencia (Spain); Chiva, S. [Univ. Jaume I, Dept. of Mechnical Engineering and Construction, Castellon (Spain); Abd El Aziz Essa, M. [Univ. Politecnica de Valencia, Inst. de Ingenieria Energetica, Valencia (Spain); Mendes, S. [Univ. Autonoma de Nuevo Leon, Facultad de Ingenieria Mecanica y Electrica (Mexico)
2011-07-01
A set of air-water experiments have been performed under isothermal upward concurrent flow in a vertical column. The interfacial velocity, interfacial area of the bubbles and the void fraction distributions was obtained. Numerical validation of these results for bubbly flow conditions were performed by coupling a Lagrangian code which tracks the 3D motion of the individual bubbles, with an Eulerian one. Both Lagrangian and Eulerian calculations were performed in parallel and iterative self-consistent method was developed. The bubbles-induced turbulence is an important issue considered, to obtain good predictions of experimental results. (author)
Simulation of MILD combustion using Perfectly Stirred Reactor model
Chen, Z.
2016-07-06
A simple model based on a Perfectly Stirred Reactor (PSR) is proposed for moderate or intense low-oxygen dilution (MILD) combustion. The PSR calculation is performed covering the entire flammability range and the tabulated chemistry approach is used with a presumed joint probability density function (PDF). The jet, in hot and diluted coflow experimental set-up under MILD conditions, is simulated using this reactor model for two oxygen dilution levels. The computed results for mean temperature, major and minor species mass fractions are compared with the experimental data and simulation results obtained recently using a multi-environment transported PDF approach. Overall, a good agreement is observed at three different axial locations for these comparisons despite the over-predicted peak value of CO formation. This suggests that MILD combustion can be effectively modelled by the proposed PSR model with lower computational cost.
Directory of Open Access Journals (Sweden)
Dewa Ngakan Ketut Putra Negara
2012-11-01
Full Text Available Deflection has an important role in order to design structure or machine component, beside consideration of stresscalculation. This is due to although stress is still smaller then stress allowed by material strength, but probably happen thatdeflection exceeds limit allowed. That condition affects serious hazard on machine elements or structure due to it can affectof component deviate from its main function. One of element which is often experience of deflection is beam. Beams playsignificant roles in many engineering applications, including buildings, bridges, automobiles, and airplane structures. In thisresearch, material to be used was Steel ASTM 1060, with specimen in the form of curved beam. Physical condition of beamwas modeled use of BEAM3 2D. Variation of loads to be applied were W = 100, 150, 200, 250, 300, 350, 400, 450, 500, and550 gr in vertical direction. The result of simulation was verificated by analytical and experimental data. Evaluation wascarried out by statistical test (t-test. The result of simulation is categorized to be good if the result of simulation is samewith analytical and experimental data. The result of research shows that loading has a significant effect on the deflection.The higher load affect the higher of deflection Modeling use of BEAM3 2D gave good result of deflection. This is showedfrom t-test have done, where the result of simulation was same with analytical and experimental data. Other advantage ofsimulation was deflection result obtained was not limited only at the end of beam, but it can predict of deflection at eachnode or point desired
Experimental analysis and dynamic simulation of a novel high-temperature solar cooling system
International Nuclear Information System (INIS)
Buonomano, Annamaria; Calise, Francesco; D’Accadia, Massimo Dentice; Ferruzzi, Gabriele; Frascogna, Sabrina; Palombo, Adolfo; Russo, Roberto; Scarpellino, Marco
2016-01-01
Highlights: • The paper presents an innovative high temperature solar cooling system. • The system is based on novel flat-plate evacuated solar thermal collectors. • Results of an experimental campaign in Saudi Arabia are reported. • A dynamic simulation model and a detailed economic analyses are developed. • Results show that the collector and the system as a whole exhibit excellent performance. - Abstract: This paper presents experimental and numerical analyses of a novel high-temperature solar cooling system based on innovative flat-plate evacuated solar thermal collectors (SC). This is the first solar cooling system, including a double-effect absorption chiller, which is based on non-concentrating solar thermal collectors. The aim of the paper is prove the technical and economic feasibility of the system, also presenting a comparison with a conventional technology, based on concentrating solar thermal collectors. To this scope, an experimental setup has been installed in Saudi Arabia. Here, several measurement devices are installed in order to monitor and control all the thermodynamic parameters of the system. The paper presents some of the main results of this experimental campaign, showing temperatures, powers, energies and efficiencies for a selected period. Experimental results showed that collector peak efficiency is higher than 60%, whereas daily average efficiency is around 40%. This prototypal solar cooling system has been numerically analysed, developing a dynamic simulation model aiming at predicting system performance. For a representative operating period, numerical data were compared with the experimental one, showing an excellent accuracy of the model. A similar system, equipped with Parabolic Trough solar thermal collectors (PTC) was also simulated in order to compare the novel solar collectors with such reference technology. For both systems a detailed thermo-economic model has been implemented in order to perform such comparison also
Experimental model of bladder instability in rabbits
Directory of Open Access Journals (Sweden)
Balasteghin K.T.
2003-01-01
Full Text Available OBJECTIVE: Propose a new experimental model of bladder instability in rabbits after partial bladder obstruction. MATERIALS AND METHODS: Thirty North Folk male rabbits, weighting 1,700 to 2,820 g (mean: 2,162 g were studied. The animals were distributed in 2 experimental groups, formed by 15 rabbits each: Group 1 - clinical control. In this group there was no surgical intervention; Group 2 - bladder outlet obstruction. In this group, after anesthetizing the animal, urethral cannulation with Foley catheter 10F was performed and then an adjustable plastic bracelet was passed around the bladder neck. It was then adjusted in order to not constrict the urethra. The following parameters were studied in M1 - pre-operative period; M2 - 4 weeks post-operatively moments: 1- urine culture; 2- cystometric study; 3- serum creatinine and BUN. RESULTS: Bladder weight was 2.5 times larger in the group with obstruction than in the control group. Cystometric evaluation showed a significant increase in maximal vesical volume in the final moment at Group G2. However, there was no statistically significant difference among the groups studied. There was no statistically significant difference between maximal detrusor pressure and vesical compliance in the different moments or in the studied groups. There was an absence of uninhibited detrusor contractions in all the animals in group 1, and involuntary contractions were detected in 93% of group 2 animals. There was no significant variation in BUN and serum creatinine either among the groups or in the same group. CONCLUSIONS: We observed in the group with obstruction a bladder weight 2.5 higher than normal bladders. We detected involuntary contractions in 93% of the animals in group 2, establishing this experimental model as appropriate to secondary bladder instability and partial bladder outlet obstruction.
Simulation models for tokamak plasmas
International Nuclear Information System (INIS)
Dimits, A.M.; Cohen, B.I.
1992-01-01
Two developments in the nonlinear simulation of tokamak plasmas are described: (A) Simulation algorithms that use quasiballooning coordinates have been implemented in a 3D fluid code and a 3D partially linearized (Δf) particle code. In quasiballooning coordinates, one of the coordinate directions is closely aligned with that of the magnetic field, allowing both optimal use of the grid resolution for structures highly elongated along the magnetic field as well as implementation of the correct periodicity conditions with no discontinuities in the toroidal direction. (B) Progress on the implementation of a likeparticle collision operator suitable for use in partially linearized particle codes is reported. The binary collision approach is shown to be unusable for this purpose. The algorithm under development is a complete version of the test-particle plus source-field approach that was suggested and partially implemented by Xu and Rosenbluth
Directory of Open Access Journals (Sweden)
Bourseau P.
2006-11-01
Full Text Available On propose un modèle de désactivation lente d'un catalyseur de répartition poreuse bimodale par dépôt solide d'un des produits de réaction dans les pores. Le dépôt solide catalyse également la réaction, la désactivation s'effectuant par diminution de la surface spécifique et bouchage progressif des pores. Le modèle prend en compte les limitations diffusionnelles existant à l'intérieur du grain de catalyseur. Ce modèle utilise une représentation géométrique particulière des pores, et une loi de diffusion tenant compte de la variation des paramètres texturaux au cours du temps. Il suppose la connaissance expérimentale de la surface spécifique totale et de la distribution du volume poreux en fonction du diamètre des pores. Ce modèle a permis de retrouver avec un très bon accord quantitatif la courbe de captation des métaux (Ni + V en fonction du temps de fonctionnement obtenue expérimentalement pour un catalyseur d'hydrodémétallisation (HDM sur un pétrole brut de Boscan désasphalté. Il permet en outre de prédire la durée de vie et le taux d'occupation final du volume poreux d'un catalyseur d'HDM modèle. A model is proposed for the slow deactivation of a catalyst with a bimodal pore distribution by a solid deposit of one of the reaction products inside the pores. The solid deposit is by itself a catalyst for the reaction, with deactivation resulting from the progressive decrease of specific area and blockage of the pores. The model takes Intragranular diffusional limitations into account. This model uses an original geometric representation of the pores together with a diffusion law incorporating the variation of textural parameters in time. It requires the experimental determination of the total specific area and of pore volume distribution as a function of pore diameter. Numerical simulations with this model provided a very good quantitative fit with the capture curve for metals (Ni + V as a function of
Simulation of the AC corona phenomenon with experimental validation
International Nuclear Information System (INIS)
Villa, Andrea; Barbieri, Luca; Marco, Gondola; Malgesini, Roberto; Leon-Garzon, Andres R
2017-01-01
The corona effect, and in particular the Trichel phenomenon, is an important aspect of plasma physics with many technical applications, such as pollution reduction, surface and medical treatments. This phenomenon is also associated with components used in the power industry where it is, in many cases, the source of electro-magnetic disturbance, noise and production of undesired chemically active species. Despite the power industry to date using mainly alternating current (AC) transmission, most of the studies related to the corona effect have been carried out with direct current (DC) sources. Therefore, there is technical interest in validating numerical codes capable of simulating the AC phenomenon. In this work we describe a set of partial differential equations that are comprehensive enough to reproduce the distinctive features of the corona in an AC regime. The model embeds some selectable chemical databases, comprising tens of chemical species and hundreds of reactions, the thermal dynamics of neutral species and photoionization. A large set of parameters—deduced from experiments and numerical estimations—are compared, to assess the effectiveness of the proposed approach. (paper)
International Nuclear Information System (INIS)
Gunnasegaran, P; Yusoff, M Z; Abdullah, M Z
2015-01-01
This paper discusses the impact of diamond nanofluid on heat transfer characteristics in a Loop Heat Pipe (LHP). In this study, diamond nanoparticles in water with particle mass concentration ranged from 0% to 3% is considered as the operational fluid within the LHP. The experiments are carried out by manufacturing the LHP, in which the setup consists of a water tank with pump, a flat evaporator, condenser installed with two pieces of fans, two transportation lines (vapor and liquid lines), copper pipe sections for attachment of the thermocouples and power supply. The uniqueness of the current experimental setup is the vapor line of LHP which is made of transparent plastic tube to visualize the fluid flow patterns. The experimental results are verified by Finite Element (FE) simulation using a three-dimensional (3D) model based on the heat transfer by conduction where the LHP as a whole is modeled by assuming it as a conducting medium without taking into account the events occurring inside the LHP. The LHP performance is evaluated in terms of transient temperature distribution and total thermal resistance (R t ). The experimental and simulation results are found in good agreement. (paper)
Directory of Open Access Journals (Sweden)
Sanjeev Jakhar
2016-06-01
Full Text Available Earth air heat exchanger (EAHE systems are insufficient to meet the thermal comfort requirements in winter conditions. The low heating potential of such systems can be improved by integrating the system with solar air heating duct (SAHD. The aim of this paper is to present a model to estimate the heating potential for EAHE system with and without SAHD. The model is generated using TRNSYS 17 simulation tool and validated against experimental investigation on an experimental set-up in Ajmer, India. The experiment was done during the winter season, where the system was evaluated for different inlet flow velocities, length and depth of buried pipe. From the experimentation, it was observed that the depth of 3.7 m is sufficient for pipe burial and the 34 m length of pipe is sufficient to get optimum EAHE outlet temperature. It is also observed that increase in flow velocity results in drop in EAHE outlet temperature, while room temperature is found to increase for higher velocities (5 m/s. The COP of the system also increased up to 6.304 when assisted with solar air heating duct. The results obtained from the experiment data are in good agreement with simulated results within the variation of up to 7.9%.
Park, Chanhun; Nam, Hee-Geun; Lee, Ki Bong; Mun, Sungyong
2014-10-24
The economically-efficient separation of formic acid from acetic acid and succinic acid has been a key issue in the production of formic acid with the Actinobacillus bacteria fermentation. To address this issue, an optimal three-zone simulated moving bed (SMB) chromatography for continuous separation of formic acid from acetic acid and succinic acid was developed in this study. As a first step for this task, the adsorption isotherm and mass-transfer parameters of each organic acid on the qualified adsorbent (Amberchrom-CG300C) were determined through a series of multiple frontal experiments. The determined parameters were then used in optimizing the SMB process for the considered separation. During such optimization, the additional investigation for selecting a proper SMB port configuration, which could be more advantageous for attaining better process performances, was carried out between two possible configurations. It was found that if the properly selected port configuration was adopted in the SMB of interest, the throughout and the formic-acid product concentration could be increased by 82% and 181% respectively. Finally, the optimized SMB process based on the properly selected port configuration was tested experimentally using a self-assembled SMB unit with three zones. The SMB experimental results and the relevant computer simulation verified that the developed process in this study was successful in continuous recovery of formic acid from a ternary organic-acid mixture of interest with high throughput, high purity, high yield, and high product concentration. Copyright © 2014 Elsevier B.V. All rights reserved.
A multi-scale experimental and simulation approach for fractured subsurface systems
Viswanathan, H. S.; Carey, J. W.; Frash, L.; Karra, S.; Hyman, J.; Kang, Q.; Rougier, E.; Srinivasan, G.
2017-12-01
Fractured systems play an important role in numerous subsurface applications including hydraulic fracturing, carbon sequestration, geothermal energy and underground nuclear test detection. Fractures that range in scale from microns to meters and their structure control the behavior of these systems which provide over 85% of our energy and 50% of US drinking water. Determining the key mechanisms in subsurface fractured systems has been impeded due to the lack of sophisticated experimental methods to measure fracture aperture and connectivity, multiphase permeability, and chemical exchange capacities at the high temperature, pressure, and stresses present in the subsurface. In this study, we developed and use microfluidic and triaxial core flood experiments required to reveal the fundamental dynamics of fracture-fluid interactions. In addition we have developed high fidelity fracture propagation and discrete fracture network flow models to simulate these fractured systems. We also have developed reduced order models of these fracture simulators in order to conduct uncertainty quantification for these systems. We demonstrate an integrated experimental/modeling approach that allows for a comprehensive characterization of fractured systems and develop models that can be used to optimize the reservoir operating conditions over a range of subsurface conditions.
A model management system for combat simulation
Dolk, Daniel R.
1986-01-01
The design and implementation of a model management system to support combat modeling is discussed. Structured modeling is introduced as a formalism for representing mathematical models. A relational information resource dictionary system is developed which can accommodate structured models. An implementation is described. Structured modeling is then compared to Jackson System Development (JSD) as a methodology for facilitating discrete event simulation. JSD is currently better at representin...
HVDC System Characteristics and Simulation Models
Energy Technology Data Exchange (ETDEWEB)
Moon, S.I.; Han, B.M.; Jang, G.S. [Electric Enginnering and Science Research Institute, Seoul (Korea)
2001-07-01
This report deals with the AC-DC power system simulation method by PSS/E and EUROSTAG for the development of a strategy for the reliable operation of the Cheju-Haenam interconnected system. The simulation using both programs is performed to analyze HVDC simulation models. In addition, the control characteristics of the Cheju-Haenam HVDC system as well as Cheju AC system characteristics are described in this work. (author). 104 figs., 8 tabs.
Physically realistic modeling of maritime training simulation
Cieutat , Jean-Marc
2003-01-01
Maritime training simulation is an important matter of maritime teaching, which requires a lot of scientific and technical skills.In this framework, where the real time constraint has to be maintained, all physical phenomena cannot be studied; the most visual physical phenomena relating to the natural elements and the ship behaviour are reproduced only. Our swell model, based on a surface wave simulation approach, permits to simulate the shape and the propagation of a regular train of waves f...
Software-Engineering Process Simulation (SEPS) model
Lin, C. Y.; Abdel-Hamid, T.; Sherif, J. S.
1992-01-01
The Software Engineering Process Simulation (SEPS) model is described which was developed at JPL. SEPS is a dynamic simulation model of the software project development process. It uses the feedback principles of system dynamics to simulate the dynamic interactions among various software life cycle development activities and management decision making processes. The model is designed to be a planning tool to examine tradeoffs of cost, schedule, and functionality, and to test the implications of different managerial policies on a project's outcome. Furthermore, SEPS will enable software managers to gain a better understanding of the dynamics of software project development and perform postmodern assessments.
Systematic modelling and simulation of refrigeration systems
DEFF Research Database (Denmark)
Rasmussen, Bjarne D.; Jakobsen, Arne
1998-01-01
The task of developing a simulation model of a refrigeration system can be very difficult and time consuming. In order for this process to be effective, a systematic method for developing the system model is required. This method should aim at guiding the developer to clarify the purpose...... of the simulation, to select appropriate component models and to set up the equations in a well-arranged way. In this paper the outline of such a method is proposed and examples showing the use of this method for simulation of refrigeration systems are given....
Experimental models of chronic subdural hematoma.
D'Abbondanza, Josephine A; Loch Macdonald, R
2014-02-01
Chronic subdural hematoma (CSDH) is a common neurosurgical problem. Most studies of pathogenesis and treatment involve humans. Advances in understanding of human diseases may be made using animal models. We reviewed all animal models of CSDH and report here their results, conclusions and limitations in order to set a baseline upon which further advanced experimental work related to this disease can be made. PubMed, Medline, Embase and ISI Web of Knowledge were searched with no time limits using the keyword 'chronic subdural hematoma' and MeSH term 'hematoma, subdural, chronic'. The authors reviewed all papers written related to this disease and selected all publications involving animals. There were no other restrictions. The findings and conclusions of the papers are summarized here. No formal analysis was done because of the variation in species used, methods for induction of CSDH, times of assessment and reporting of results. Attempts to create CSDH have been made in mice, rats, cats, dogs and monkeys. Methods include injection or surgical implantation of clotted blood or various other blood products and mixtures into the potential subdural space or the subcutaneous space. No intracranial model produced a progressively expanding CSDH. Transient hematoma expansion with liquification could be produced by subcutaneous injections in some models. Spontaneous subdural blood collections were found after creation of hydrocephalus in mice by systemic injection of the neurotoxin, 6-aminonicotinamide. The histology of the hematoma membranes in several models resembles the appearance in humans. None of the models has been replicated since its first description. We did not find a report of a reproducible, well-described animal model of human CSDH.
Hadronic models and experimental data for the neutrino beam production
Collazuol, G; Guglielmi, A M; Sala, P R
2000-01-01
The predictions of meson production by 450 GeV/c protons on Be using the Monte Carlo FLUKA standalone and GEANT-FLUKA and GEANT-GHEISHA in GEANT are compared with available experimental measurements. The comparison enlightens the improvements of the hadronic generator models of the present standalone code FLUKA with respect to the 1992 version which is embedded into GEANT-FLUKA. Worse results were obtained with the GHEISHA package. A complete simulation of the SPS neutrino beam line at CERN showed significant variations in the intensity and composition of the neutrino beam when FLUKA standalone instead of the GEANT-FLUKA package is used to simulate particle production in the Be target.
Hadronic models and experimental data for the neutrino beam production
International Nuclear Information System (INIS)
Collazuol, G.; Ferrari, A.; Guglielmi, A.; Sala, P.R.
2000-01-01
The predictions of meson production by 450 GeV/c protons on Be using the Monte Carlo FLUKA standalone and GEANT-FLUKA and GEANT-GHEISHA in GEANT are compared with available experimental measurements. The comparison enlightens the improvements of the hadronic generator models of the present standalone code FLUKA with respect to the 1992 version which is embedded into GEANT-FLUKA. Worse results were obtained with the GHEISHA package. A complete simulation of the SPS neutrino beam line at CERN showed significant variations in the intensity and composition of the neutrino beam when FLUKA standalone instead of the GEANT-FLUKA package is used to simulate particle production in the Be target
CFD Modeling and Experimental Validation of a Solar Still
Directory of Open Access Journals (Sweden)
Mahmood Tahir
2017-01-01
Full Text Available Earth is the densest planet of the solar system with total area of 510.072 million square Km. Over 71.68% of this area is covered with water leaving a scant area of 28.32% for human to inhabit. The fresh water accounts for only 2.5% of the total volume and the rest is the brackish water. Presently, the world is facing chief problem of lack of potable water. This issue can be addressed by converting brackish water into potable through a solar distillation process and solar still is specially assigned for this purpose. Efficiency of a solar still explicitly depends on its design parameters, such as wall material, chamber depth, width and slope of the zcondensing surface. This study was aimed at investigating the solar still parameters using CFD modeling and experimental validation. The simulation data of ANSYS-FLUENT was compared with actual experimental data. A close agreement among the simulated and experimental results was seen in the presented work. It reveals that ANSYS-FLUENT is a potent tool to analyse the efficiency of the new designs of the solar distillation systems.
Modeling and simulation in inquiry learning: Checking solutions and giving intelligent advice
Bravo, C.; van Joolingen, W.R.; de Jong, T.
2006-01-01
Inquiry learning is a didactic approach in which students acquire knowledge and skills through processes of theory building and experimentation. Computer modeling and simulation can play a prominent role within this approach. Students construct representations of physical systems using modeling.
Experimental limits from ATLAS on Standard Model Higgs production.
ATLAS, collaboration
2012-01-01
Experimental limits from ATLAS on Standard Model Higgs production in the mass range 110-600 GeV. The solid curve reflects the observed experimental limits for the production of a Higgs of each possible mass value (horizontal axis). The region for which the solid curve dips below the horizontal line at the value of 1 is excluded with a 95% confidence level (CL). The dashed curve shows the expected limit in the absence of the Higgs boson, based on simulations. The green and yellow bands correspond (respectively) to 68%, and 95% confidence level regions from the expected limits. Higgs masses in the narrow range 123-130 GeV are the only masses not excluded at 95% CL
Injection Moulding Simulation and Experimental Validation of Hearing Aid Shells
DEFF Research Database (Denmark)
Islam, Aminul; Li, Xiaoliu
and warpage were taken as the main comparison criteria. Different parameter settings in Moldex3D were investigated to find their influence on the accuracy of the simulation. Results showed that the injection molding process prediction from the simulation was relatively precise when the nozzle geometry...
Directory of Open Access Journals (Sweden)
Bernard J.
2009-11-01
Full Text Available Rigorous electrochemical models to simulate the cycling performance of batteries have been successfully developed and reported in the literature. They constitute a very promising approach for State-of-Charge (SoC estimation based on the physics of the cell with regards to other methods since SoC is an internal parameter of these physical models. However, the computational time needed to solve electrochemical battery models for online applications requires to develop a simplified physics-based battery model. In this work, our goal is to present and validate an advanced 0D-electrochemical model of a Ni-MH cell, as an example. This lumped-parameter model will be used to design an extended Kalman filter to predict the SoC of a Ni-MH pack. It is presented, followed by an extensive experimental study conducted on Ni-MH cells to better understand the mechanisms of physico-chemical phenomena occurring at both electrodes and support the model development. The last part of the paper focuses on the evaluation of the model with regards to experimental results obtained on Ni-MH sealed cells but also on the related commercial HEV battery pack. Des modèles électrochimiques fins permettant de simuler le comportement de batteries ont été développés avec succès et reportés dans la littérature. Ils constituent une alternative aux méthodes classiques pour estimer l’état de charge (SoC pour State of Charge des batteries, cette variable étant ici un paramètre interne du modèle physique. Cependant, pour les applications embarquées, il est nécessaire de développer des modèles simplifiés sur la base de ces modèles physiques afin de diminuer le temps de calcul nécessaire à la résolution des équations. Ici, nous présenterons à titre d’exemple un modèle électrochimique 0D avancé d’un accumulateur NiMH et sa validation. Ce modèle à paramètres concentrés sera utilisé pour réaliser un filtre de Kalman qui permettra la prédiction de l
Experimental and theoretical requirements for fuel modelling
International Nuclear Information System (INIS)
Gatesoupe, J.P.
1979-01-01
From a scientific point of view it may be considered that any event in the life of a fuel pin under irradiation should be perfectly well understood and foreseen from that deterministic point of view, the whole behaviour of the pin maybe analysed and dismantled with a specific function for every component part and each component part related to one basic phenomenon which can be independently studied on pure physical grounds. When extracted from the code structure the subroutine is studied for itself by specialists who try to keep as close as possible to the physics involved in the phenomenon; that often leads to an impressive luxury in details and a subsequent need for many unavailable input data. It might seem more secure to follow that approach since it tries to be firmly based on theoretical grounds. One should think so if the phenomenological situation in the pin were less complex than it is. The codes would not be adequate for off-normal operating conditions since for the accidental transient conditions the key-phenomena would not be the same as for steady-state or slow transient conditions. The orientation given to fuel modelling is based on our two main technological constraints which are: no fuel melting; no cladding failure; no excessive cladding deformation. In this context, the only relevant models are those which have a significant influence on the maximum temperatures in the fuel or on the cladding damage hence the selection between key models and irrelevant models which will next be done. A rather pragmatic view is kept on codification with a special focus on a few determinant aspects of fuel behaviour and no attention to models which are nothing but decorative. Fuel modeling is merely considered as a link between experimental knowledge; it serves as a guide for further improvements in fuel design and as so happens to be quite useful. On this basis the main lacks in of fuel behaviour is described. These are mainly concerning: thermal transfer through
Deriving simulators for hybrid Chi models
Beek, van D.A.; Man, K.L.; Reniers, M.A.; Rooda, J.E.; Schiffelers, R.R.H.
2006-01-01
The hybrid Chi language is formalism for modeling, simulation and verification of hybrid systems. The formal semantics of hybrid Chi allows the definition of provably correct implementations for simulation, verification and realtime control. This paper discusses the principles of deriving an
Modeling and simulation for RF system design
Frevert, Ronny; Jancke, Roland; Knöchel, Uwe; Schwarz, Peter; Kakerow, Ralf; Darianian, Mohsen
2005-01-01
Focusing on RF specific modeling and simulation methods, and system and circuit level descriptions, this work contains application-oriented training material. Accompanied by a CD- ROM, it combines the presentation of a mixed-signal design flow, an introduction into VHDL-AMS and Verilog-A, and the application of commercially available simulators.
International Nuclear Information System (INIS)
Bianchini, Alessandro; Balduzzi, Francesco; Bachant, Peter; Ferrara, Giovanni; Ferrari, Lorenzo
2017-01-01
Highlights: • 2D CFD simulations compared to experimental tow-tank data on the RVAT test model. • The use of CFD with open-field-like boundaries is suggested. • A reliable estimation of the turbine performance and the wake structure is obtained. • The transitional turbulence model is recommended for low TSRs and/or small rotors. • The wake analysis identified the main vortical structures generated by the blades. - Abstract: Thanks to the continuous improvement of calculation resources, computational fluid dynamics (CFD) is expected to provide in the next few years a cost-effective and accurate tool to improve the understanding of the unsteady aerodynamics of Darrieus wind turbines. This rotor type is in fact increasingly welcome by the wind energy community, especially in case of small size applications and/or non-conventional installation sites. In the present study, unique tow tank experimental data on the performance curve and the near-wake structure of a Darrieus rotor were used as a benchmark to validate the effectiveness of different CFD approaches. In particular, a dedicated analysis is provided to assess the suitability, the effectiveness and the future prospects of simplified two-dimensional (2D) simulations. The correct definition of the computational domain, the selection of the turbulence models and the correction of simulated data for the parasitic torque components are discussed in this study. Results clearly show that, (only) if properly set, two-dimensional CFD simulations are able to provide - with a reasonable computational cost - an accurate estimation of the turbine performance and also quite reliably describe the attended flow-field around the rotor and its wake.
CFD simulation of a burner for syngas characterization and experimental validation
Energy Technology Data Exchange (ETDEWEB)
Fantozzi, Francesco; Desideri, Umberto [University of Perugia (Italy). Dept. of Industrial Engineering], Emails: fanto@unipg.it, umberto.desideri@unipg.it; D' Amico, Michele [University of Perugia (Italy). Dept. of Energetic Engineering], E-mail: damico@crbnet.it
2009-07-01
Biomass and waste are distributed and renewable energy sources that may contribute effectively to sustainability if used on a small and micro scale. This requires the transformation through efficient technologies (gasification, pyrolysis and anaerobic digestion) into a suitable gaseous fuel to use in small internal combustion engines and gas turbines. The characterization of biomass derived syngas during combustion is therefore a key issue to improve the performance of small scale integrated plants because synthesis gas show significant differences with respect to Natural Gas (mixture of gases, low calorific value, hydrogen content, tar and particulate content) that may turn into ignition problems, combustion instabilities, difficulties in emission control and fouling. To this aim a burner for syngas combustion and LHV measurement through mass and energy balance was realized and connected to the rotary-kiln laboratory scale pyrolyzer at the Department of Industrial Engineering of the University of Perugia. A computational fluid dynamics (CFD) simulation of the burner was carried out considering the combustion of propane to investigate temperature and pressure distribution, heat transmission and distribution of the combustion products and by products. The simulation was carried out using the CFD program Star-CD. Before the simulation a geometrical model of the burner was built and the volume of model was subdivided in cells. A sensibility analysis of cells was carried out to estimate the approximation degree of the model. Experimental data about combustion emission were carried out with the propane combustion in the burner, the comparison between numerical results and experimental data was studied to validate the simulation for future works involved with the combustion of treated or raw (syngas with tar) syngas obtained from pyrolysis process. (author)
International Nuclear Information System (INIS)
Villagran-Muniz, M; Sobral, H; Navarro-Gonzalez, R; Velazquez, P F; Raga, A C
2003-01-01
Tabletop laboratory experiments have been used to simulate natural lightning, interacting explosions and astrophysical jets. When a high-energy laser pulse is focused in air, a laser-induced plasma (LIP) is produced, that generates a shock wave and an adiabatic expansion of the gas. In our work we have used LIPs in order to simulate lightning, for the study of chemical reactions relevant to atmospheric science. Several diagnostics have been applied to our LIPs, such as deflectometry, shadowgraphy and interferometry, which yield full spatial information of the process (electron density and temperature, the position of the shock wave fronts and the expansion of the hot gas), with a time resolution that ranges from nanoseconds to milliseconds. A new diagnostic alternative was implemented for shadowgraphy, which uses either continuous lasers or conventional light sources. The experimental results have been reproduced by hydrodynamic codes that we have developed. With astrophysical applications in mind, we have simulated and diagnosed the interaction of two explosions, with the aforementioned techniques. For this purpose, two LIPs are synchronized and diagnosed spatially and temporarily. Also, by producing the LIP in a glass sphere with a nozzle that ejects a shock wave and hot gas, we are able to simulate astrophysical jets. With such experiments, astrophysical models developed by us have been validated, showing excellent agreement between experiments and numerical simulations
Numerical and experimental approaches to simulate soil clogging in porous media
Kanarska, Yuliya; LLNL Team
2012-11-01
Failure of a dam by erosion ranks among the most serious accidents in civil engineering. The best way to prevent internal erosion is using adequate granular filters in the transition areas where important hydraulic gradients can appear. In case of cracking and erosion, if the filter is capable of retaining the eroded particles, the crack will seal and the dam safety will be ensured. A finite element numerical solution of the Navier-Stokes equations for fluid flow together with Lagrange multiplier technique for solid particles was applied to the simulation of soil filtration. The numerical approach was validated through comparison of numerical simulations with the experimental results of base soil particle clogging in the filter layers performed at ERDC. The numerical simulation correctly predicted flow and pressure decay due to particle clogging. The base soil particle distribution was almost identical to those measured in the laboratory experiment. To get more precise understanding of the soil transport in granular filters we investigated sensitivity of particle clogging mechanisms to various aspects such as particle size ration, the amplitude of hydraulic gradient, particle concentration and contact properties. By averaging the results derived from the grain-scale simulations, we investigated how those factors affect the semi-empirical multiphase model parameters in the large-scale simulation tool. The Department of Homeland Security Science and Technology Directorate provided funding for this research.
WDM Systems and Networks Modeling, Simulation, Design and Engineering
Ellinas, Georgios; Roudas, Ioannis
2012-01-01
WDM Systems and Networks: Modeling, Simulation, Design and Engineering provides readers with the basic skills, concepts, and design techniques used to begin design and engineering of optical communication systems and networks at various layers. The latest semi-analytical system simulation techniques are applied to optical WDM systems and networks, and a review of the various current areas of optical communications is presented. Simulation is mixed with experimental verification and engineering to present the industry as well as state-of-the-art research. This contributed volume is divided into three parts, accommodating different readers interested in various types of networks and applications. The first part of the book presents modeling approaches and simulation tools mainly for the physical layer including transmission effects, devices, subsystems, and systems), whereas the second part features more engineering/design issues for various types of optical systems including ULH, access, and in-building system...
Experimental and simulation studies on mineral trapping of CO2 with brine
International Nuclear Information System (INIS)
Soong, Y.; Goodman, A.L.; McCarthy-Jones, J.R.; Baltrus, J.P.
2004-01-01
The reaction of carbon dioxide (CO 2 ) with brine samples collected from the Oriskany Formation in Indiana County, PA, was investigated in an autoclave reactor under various conditions. A geochemical code, PHREEQC, was used as to simulate the reaction in the autoclave reactor. The combined experimental and modeling data suggests that pH (pH > 9) plays a key role in the formation of carbonate minerals. The effects of temperature and CO 2 pressure have a lesser impact on the formation of carbonate minerals
An experimental and kinetic modeling study of glycerol pyrolysis
International Nuclear Information System (INIS)
Fantozzi, F.; Frassoldati, A.; Bartocci, P.; Cinti, G.; Quagliarini, F.; Bidini, G.; Ranzi, E.M.
2016-01-01
Highlights: • Glycerol pyrolysis can produce about 44–48%v hydrogen at 750–800 °C. • A simplified 452 reactions kinetic model of glycerol pyrolysis has been developed. • The model has good agreement with experimental data. • Non condensable gas yields can reach 70%. - Abstract: Pyrolysis of glycerol, a by-product of the biodiesel industry, is an important potential source of hydrogen. The obtained high calorific value gas can be used either as a fuel for combined heat and power (CHP) generation or as a transportation fuel (for example hydrogen to be used in fuel cells). Optimal process conditions can improve glycerol pyrolysis by increasing gas yield and hydrogen concentration. A detailed kinetic mechanism of glycerol pyrolysis, which involves 137 species and more than 4500 reactions, was drastically simplified and reduced to a new skeletal kinetic scheme of 44 species, involved in 452 reactions. An experimental campaign with a batch pyrolysis reactor was properly designed to further validate the original and the skeletal mechanisms. The comparisons between model predictions and experimental data strongly suggest the presence of a catalytic process promoting steam reforming of methane. High pyrolysis temperatures (750–800 °C) improve process performances and non-condensable gas yields of 70%w can be achieved. Hydrogen mole fraction in pyrolysis gas is about 44–48%v. The skeletal mechanism developed can be easily used in Computational Fluid Dynamic software, reducing the simulation time.
Thermo-hydraulic simulations of the experimental fast reactor core
International Nuclear Information System (INIS)
Silveira Luz, M. da; Braz Filho, F.A.; Borges, E.M.
1985-01-01
A study of the core and performance of metallic fuel of the experimental fast reactor, from the thermal-hydraulic point of view, was carried out employing the COBRA IV-I code. The good safety characteristics of this reactor and the feasibility of using metallic fuel in experimental fast reactor were demonstrated. (Author) [pt
Magnetosphere Modeling: From Cartoons to Simulations
Gombosi, T. I.
2017-12-01
Over the last half a century physics-based global computer simulations became a bridge between experiment and basic theory and now it represents the "third pillar" of geospace research. Today, many of our scientific publications utilize large-scale simulations to interpret observations, test new ideas, plan campaigns, or design new instruments. Realistic simulations of the complex Sun-Earth system have been made possible by the dramatically increased power of both computing hardware and numerical algorithms. Early magnetosphere models were based on simple E&M concepts (like the Chapman-Ferraro cavity) and hydrodynamic analogies (bow shock). At the beginning of the space age current system models were developed culminating in the sophisticated Tsyganenko-type description of the magnetic configuration. The first 3D MHD simulations of the magnetosphere were published in the early 1980s. A decade later there were several competing global models that were able to reproduce many fundamental properties of the magnetosphere. The leading models included the impact of the ionosphere by using a height-integrated electric potential description. Dynamic coupling of global and regional models started in the early 2000s by integrating a ring current and a global magnetosphere model. It has been recognized for quite some time that plasma kinetic effects play an important role. Presently, global hybrid simulations of the dynamic magnetosphere are expected to be possible on exascale supercomputers, while fully kinetic simulations with realistic mass ratios are still decades away. In the 2010s several groups started to experiment with PIC simulations embedded in large-scale 3D MHD models. Presently this integrated MHD-PIC approach is at the forefront of magnetosphere simulations and this technique is expected to lead to some important advances in our understanding of magnetosheric physics. This talk will review the evolution of magnetosphere modeling from cartoons to current systems
Siegfried, Robert
2014-01-01
Robert Siegfried presents a framework for efficient agent-based modeling and simulation of complex systems. He compares different approaches for describing structure and dynamics of agent-based models in detail. Based on this evaluation the author introduces the "General Reference Model for Agent-based Modeling and Simulation" (GRAMS). Furthermore he presents parallel and distributed simulation approaches for execution of agent-based models -from small scale to very large scale. The author shows how agent-based models may be executed by different simulation engines that utilize underlying hard
SEIR model simulation for Hepatitis B
Side, Syafruddin; Irwan, Mulbar, Usman; Sanusi, Wahidah
2017-09-01
Mathematical modelling and simulation for Hepatitis B discuss in this paper. Population devided by four variables, namely: Susceptible, Exposed, Infected and Recovered (SEIR). Several factors affect the population in this model is vaccination, immigration and emigration that occurred in the population. SEIR Model obtained Ordinary Differential Equation (ODE) non-linear System 4-D which then reduces to 3-D. SEIR model simulation undertaken to predict the number of Hepatitis B cases. The results of the simulation indicates the number of Hepatitis B cases will increase and then decrease for several months. The result of simulation using the number of case in Makassar also found the basic reproduction number less than one, that means, Makassar city is not an endemic area of Hepatitis B.
Maintenance Personnel Performance Simulation (MAPPS) model
International Nuclear Information System (INIS)
Siegel, A.I.; Bartter, W.D.; Wolf, J.J.; Knee, H.E.; Haas, P.M.
1984-01-01
A stochastic computer model for simulating the actions and behavior of nuclear power plant maintenance personnel is described. The model considers personnel, environmental, and motivational variables to yield predictions of maintenance performance quality and time to perform. The mode has been fully developed and sensitivity tested. Additional evaluation of the model is now taking place
Turbine modelling for real time simulators
International Nuclear Information System (INIS)
Oliveira Barroso, A.C. de; Araujo Filho, F. de
1992-01-01
A model for vapor turbines and its peripherals has been developed. All the important variables have been included and emphasis has been given for the computational efficiency to obtain a model able to simulate all the modeled equipment. (A.C.A.S.)
Experimental ship fire measurements with simulated radioactive cargo
International Nuclear Information System (INIS)
Koski, J.A.; Arviso, M.; Bobbe, J.G.; Wix, S.D.; Cole, J.K.; Hohnstreiter, G.F.; Beene, D.E. Jr.
1997-10-01
Results from a series of eight test fires ranging in size from 2.2 to 18.8 MW conducted aboard the Coast Guard fire test ship Mayo Lykes at Mobile, Alabama are presented and discussed. Tests aboard the break bulk type cargo ship consisted of heptane spray fires simulating engine room and galley fires, wood crib fires simulating cargo hold fires, and pool fires staged for comparison to land based regulatory fire results. Primary instrumentation for the tests consisted of two pipe calorimeters that simulated a typical package shape for radioactive materials packages
Experimental ship fire measurements with simulated radioactive cargo
International Nuclear Information System (INIS)
Koski, J.A.; Arvisol, M.; Bobbe, J.G.; Wix, S.D.; Cole, J.K.; Hohnstreiter, G.F.; Wix, S.D.; Beene, D.E.; Keane, M.P.
1998-01-01
Results from a series of eight test fires ranging in size from 2.2 to 18.8 MW conducted aboard the Coast Guard fire test ship Mayo Lykes at Mobile, Alabama are presented and discussed. Tests aboard the break-bulk type cargo ship consisted of heptane spray fires simulating engine room and galley fires, wood crib fires simulating cargo hold fires, and pool fires staged for comparison to land-based regulatory fire results. Primary instrumentation for the tests consisted of two pipe calorimeters that simulated a typical package shape for radioactive materials packages. (authors)
Experimental models of autoimmune inflammatory ocular diseases
Directory of Open Access Journals (Sweden)
Fabio Gasparin
2012-04-01
Full Text Available Ocular inflammation is one of the leading causes of blindness and loss of vision. Human uveitis is a complex and heterogeneous group of diseases characterized by inflammation of intraocular tissues. The eye may be the only organ involved, or uveitis may be part of a systemic disease. A significant number of cases are of unknown etiology and are labeled idiopathic. Animal models have been developed to the study of the physiopathogenesis of autoimmune uveitis due to the difﬁculty in obtaining human eye inflamed tissues for experiments. Most of those models are induced by injection of speciﬁc photoreceptors proteins (e.g., S-antigen, interphotoreceptor retinoid-binding protein, rhodopsin, recoverin, phosducin. Non-retinal antigens, including melanin-associated proteins and myelin basic protein, are also good inducers of uveitis in animals. Understanding the basic mechanisms and pathogenesis of autoimmune ocular diseases are essential for the development of new treatment approaches and therapeutic agents. The present review describes the main experimental models of autoimmune ocular inflammatory diseases.
Modeling a nuclear reactor for experimental purposes
International Nuclear Information System (INIS)
Berta, V.T.
1980-01-01
The Loss-of-Fluid Test (LOFT) Facility is a scale model of a commercial PWR and is as fully functional and operational as the generic commercial counterpart. LOFT was designed and built for experimental purposes as part of the overall NRC reactor safety research program. The purpose of LOFT is to assess the capability of reactor safety systems to perform their intended functions during occurrences of off-normal conditions in a commercial nuclear reactor. Off-normal conditions arising from large and small break loss-of-coolant accidents (LOCA), operational transients, and anticipated transients without scram (ATWS) were to be investigated. This paper describes the LOFT model of the generic PWR and summarizes the experiments that have been conducted in the context of the significant findings involving the complex transient thermal-hydraulics and the consequent effects on the commercial reactor analytical licensing techniques. Through these techniques the validity of the LOFT model as a scaled counterpart of the generic PWR is shown
Theory, modeling, and simulation annual report, 1992
Energy Technology Data Exchange (ETDEWEB)
1993-05-01
This report briefly discusses research on the following topics: development of electronic structure methods; modeling molecular processes in clusters; modeling molecular processes in solution; modeling molecular processes in separations chemistry; modeling interfacial molecular processes; modeling molecular processes in the atmosphere; methods for periodic calculations on solids; chemistry and physics of minerals; graphical user interfaces for computational chemistry codes; visualization and analysis of molecular simulations; integrated computational chemistry environment; and benchmark computations.
Tobacco experimental model to induce urinary bladder neoplasms
Directory of Open Access Journals (Sweden)
José Alexandre Colli Neto
2014-01-01
Full Text Available OBJECTIVE: to develop an experimental model of exposure to tobacco burning (cigarette products to assess the effects of its chronic use in relation to cancers of the bladder. METHODS: the animals were chronically exposed to the burning tobacco products in a semi-open chamber to simulate smoking. Thirty young Wistar rats were divided into two groups: one with 20 animals simulating smoking for six months, and ten not exposed control animals for the same period. After exposure by inhalation of cigarette smoke, animals were euthanized and subjected to histopathological study of the bladder wall. RESULTS: no tumor was found but mild and non significant alterations. The studies of hemo-oximetry (carboxyhemoglobin and methemoglobin and the concentration of carbon dioxide (CO2 confirm that the animals were exposed to high concentrations of tobacco smoke and its derivatives. CONCLUSION: no bladder mucosal neoplasia was found in the pathological study of animals. The developed experimental models were highly efficient, practical and easy to use and can be used in other similar studies to determine the harmful effects caused by smoking.
Modeling and simulation with operator scaling
Cohen, Serge; Meerschaert, Mark M.; Rosiński, Jan
2010-01-01
Self-similar processes are useful in modeling diverse phenomena that exhibit scaling properties. Operator scaling allows a different scale factor in each coordinate. This paper develops practical methods for modeling and simulating stochastic processes with operator scaling. A simulation method for operator stable Levy processes is developed, based on a series representation, along with a Gaussian approximation of the small jumps. Several examples are given to illustrate practical application...
Tian, Jiting; Zhou, Wei; Feng, Qijie; Zheng, Jian
2018-03-01
An unsolved problem in research of sputtering from metals induced by energetic large cluster ions is that molecular dynamics (MD) simulations often produce sputtering yields much higher than experimental results. Different from the previous simulations considering only elastic atomic interactions (nuclear stopping), here we incorporate inelastic electrons-atoms interactions (electronic stopping, ES) into MD simulations using a friction model. In this way we have simulated continuous 45° impacts of 10-20 keV C60 on a Ag(111) surface, and found that the calculated sputtering yields can be very close to the experimental results when the model parameter is appropriately assigned. Conversely, when we ignore the effect of ES, the yields are much higher, just like the previous studies. We further expand our research to the sputtering of Au induced by continuous keV C60 or Ar100 bombardments, and obtain quite similar results. Our study indicates that the gap between the experimental and the simulated sputtering yields is probably induced by the ignorance of ES in the simulations, and that a careful treatment of this issue is important for simulations of cluster-ion-induced sputtering, especially for those aiming to compare with experiments.
Modeling of magnetic particle suspensions for simulations
Satoh, Akira
2017-01-01
The main objective of the book is to highlight the modeling of magnetic particles with different shapes and magnetic properties, to provide graduate students and young researchers information on the theoretical aspects and actual techniques for the treatment of magnetic particles in particle-based simulations. In simulation, we focus on the Monte Carlo, molecular dynamics, Brownian dynamics, lattice Boltzmann and stochastic rotation dynamics (multi-particle collision dynamics) methods. The latter two simulation methods can simulate both the particle motion and the ambient flow field simultaneously. In general, specialized knowledge can only be obtained in an effective manner under the supervision of an expert. The present book is written to play such a role for readers who wish to develop the skill of modeling magnetic particles and develop a computer simulation program using their own ability. This book is therefore a self-learning book for graduate students and young researchers. Armed with this knowledge,...
Energy Technology Data Exchange (ETDEWEB)
Sun Qi; Groth, Alexandra; Bertram, Matthias; Waechter, Irina; Bruijns, Tom; Hermans, Roel; Aach, Til [Philips Research Europe, Weisshausstrasse 2, 52066 Aachen (Germany) and Institute of Imaging and Computer Vision, RWTH Aachen University, Sommerfeldstrasse 24, 52074 Aachen (Germany); Philips Research Europe, Weisshausstrasse 2, 52066 Aachen (Germany); Philips Healthcare, X-Ray Pre-Development, Veenpluis 4-6, 5684PC Best (Netherlands); Institute of Imaging and Computer Vision, RWTH Aachen University, Sommerfeldstrasse 24, 52074 Aachen (Germany)
2010-09-15
Purpose: Recently, image-based computational fluid dynamics (CFD) simulation has been applied to investigate the hemodynamics inside human cerebral aneurysms. The knowledge of the computed three-dimensional flow fields is used for clinical risk assessment and treatment decision making. However, the reliability of the application specific CFD results has not been thoroughly validated yet. Methods: In this work, by exploiting a phantom aneurysm model, the authors therefore aim to prove the reliability of the CFD results obtained from simulations with sufficiently accurate input boundary conditions. To confirm the correlation between the CFD results and the reality, virtual angiograms are generated by the simulation pipeline and are quantitatively compared to the experimentally acquired angiograms. In addition, a parametric study has been carried out to systematically investigate the influence of the input parameters associated with the current measuring techniques on the flow patterns. Results: Qualitative and quantitative evaluations demonstrate good agreement between the simulated and the real flow dynamics. Discrepancies of less than 15% are found for the relative root mean square errors of time intensity curve comparisons from each selected characteristic position. The investigated input parameters show different influences on the simulation results, indicating the desired accuracy in the measurements. Conclusions: This study provides a comprehensive validation method of CFD simulation for reproducing the real flow field in the cerebral aneurysm phantom under well controlled conditions. The reliability of the CFD is well confirmed. Through the parametric study, it is possible to assess the degree of validity of the associated CFD model based on the parameter values and their estimated accuracy range.
International Nuclear Information System (INIS)
Sun Qi; Groth, Alexandra; Bertram, Matthias; Waechter, Irina; Bruijns, Tom; Hermans, Roel; Aach, Til
2010-01-01
Purpose: Recently, image-based computational fluid dynamics (CFD) simulation has been applied to investigate the hemodynamics inside human cerebral aneurysms. The knowledge of the computed three-dimensional flow fields is used for clinical risk assessment and treatment decision making. However, the reliability of the application specific CFD results has not been thoroughly validated yet. Methods: In this work, by exploiting a phantom aneurysm model, the authors therefore aim to prove the reliability of the CFD results obtained from simulations with sufficiently accurate input boundary conditions. To confirm the correlation between the CFD results and the reality, virtual angiograms are generated by the simulation pipeline and are quantitatively compared to the experimentally acquired angiograms. In addition, a parametric study has been carried out to systematically investigate the influence of the input parameters associated with the current measuring techniques on the flow patterns. Results: Qualitative and quantitative evaluations demonstrate good agreement between the simulated and the real flow dynamics. Discrepancies of less than 15% are found for the relative root mean square errors of time intensity curve comparisons from each selected characteristic position. The investigated input parameters show different influences on the simulation results, indicating the desired accuracy in the measurements. Conclusions: This study provides a comprehensive validation method of CFD simulation for reproducing the real flow field in the cerebral aneurysm phantom under well controlled conditions. The reliability of the CFD is well confirmed. Through the parametric study, it is possible to assess the degree of validity of the associated CFD model based on the parameter values and their estimated accuracy range.
Modelling and Simulation of Wave Loads
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard; Thoft-Christensen, Palle
velocity can be approximated by a Gaussian Markov process. Known approximate results for the first-passage density or equivalently, the distribution of the extremes of wave loads are presented and compared with rather precise simulation results. It is demonstrated that the approximate results......A simple model of the wave load on slender members of offshore structures is described. The wave elevation of the sea state is modelled by a stationary Gaussian process. A new procedure to simulate realizations of the wave loads is developed. The simulation method assumes that the wave particle...
Modelling and Simulation of Wave Loads
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard; Thoft-Christensen, Palle
1985-01-01
velocity can be approximated by a Gaussian Markov process. Known approximate results for the first passage density or equivalently, the distribution of the extremes of wave loads are presented and compared with rather precise simulation results. It is demonstrated that the approximate results......A simple model of the wave load on stender members of offshore structures is described . The wave elevation of the sea stateis modelled by a stationary Gaussian process. A new procedure to simulate realizations of the wave loads is developed. The simulation method assumes that the wave particle...
Modeling and simulation of discrete event systems
Choi, Byoung Kyu
2013-01-01
Computer modeling and simulation (M&S) allows engineers to study and analyze complex systems. Discrete-event system (DES)-M&S is used in modern management, industrial engineering, computer science, and the military. As computer speeds and memory capacity increase, so DES-M&S tools become more powerful and more widely used in solving real-life problems. Based on over 20 years of evolution within a classroom environment, as well as on decades-long experience in developing simulation-based solutions for high-tech industries, Modeling and Simulation of Discrete-Event Systems is the only book on
Minimum-complexity helicopter simulation math model
Heffley, Robert K.; Mnich, Marc A.
1988-01-01
An example of a minimal complexity simulation helicopter math model is presented. Motivating factors are the computational delays, cost, and inflexibility of the very sophisticated math models now in common use. A helicopter model form is given which addresses each of these factors and provides better engineering understanding of the specific handling qualities features which are apparent to the simulator pilot. The technical approach begins with specification of features which are to be modeled, followed by a build up of individual vehicle components and definition of equations. Model matching and estimation procedures are given which enable the modeling of specific helicopters from basic data sources such as flight manuals. Checkout procedures are given which provide for total model validation. A number of possible model extensions and refinement are discussed. Math model computer programs are defined and listed.
Modeling and simulation of axisymmetric coating growth on nanofibers
International Nuclear Information System (INIS)
Moore, K.; Clemons, C. B.; Kreider, K. L.; Young, G. W.
2007-01-01
This work is a modeling and simulation extension of an integrated experimental/modeling investigation of a procedure to coat nanofibers and core-clad nanostructures with thin film materials using plasma enhanced physical vapor deposition. In the experimental effort, electrospun polymer nanofibers are coated with metallic materials under different operating conditions to observe changes in the coating morphology. The modeling effort focuses on linking simple models at the reactor level, nanofiber level, and atomic level to form a comprehensive model. The comprehensive model leads to the definition of an evolution equation for the coating free surface. This equation was previously derived and solved under a single-valued assumption in a polar geometry to determine the coating morphology as a function of operating conditions. The present work considers the axisymmetric geometry and solves the evolution equation without the single-valued assumption and under less restrictive assumptions on the concentration field than the previous work
Comparison of SRIM, MCNPX and GEANT simulations with experimental data for thick Al absorbers
International Nuclear Information System (INIS)
Evseev, Ivan G.; Schelin, Hugo R.; Paschuk, Sergei A.; Milhoretto, Edney; Setti, Joao A.P.; Yevseyeva, Olga; Assis, Joaquim T. de; Hormaza, Joel M.; Diaz, Katherin S.; Lopes, Ricardo T.
2010-01-01
Proton computerized tomography deals with relatively thick targets like the human head or trunk. In this case precise analytical calculation of the proton final energy is a rather complicated task, thus the Monte Carlo simulation stands out as a solution. We used the GEANT4.8.2 code to calculate the proton final energy spectra after passing a thick Al absorber and compared it with the same conditions of the experimental data. The ICRU49, Ziegler85 and Ziegler2000 models from the low energy extension pack were used. The results were also compared with the SRIM2008 and MCNPX2.4 simulations, and with solutions of the Boltzmann transport equation in the Fokker-Planck approximation.
Comparison of SRIM, MCNPX and GEANT simulations with experimental data for thick Al absorbers
Energy Technology Data Exchange (ETDEWEB)
Evseev, Ivan G. [Federal University of Technology-Parana-UTFPR, Av.7 de Setembro 3165, Curitiba-PR (Brazil); Schelin, Hugo R. [Federal University of Technology-Parana-UTFPR, Av.7 de Setembro 3165, Curitiba-PR (Brazil)], E-mail: schelin@utfpr.edu.br; Paschuk, Sergei A.; Milhoretto, Edney; Setti, Joao A.P. [Federal University of Technology-Parana-UTFPR, Av.7 de Setembro 3165, Curitiba-PR (Brazil); Yevseyeva, Olga; Assis, Joaquim T. de [Instituto Politecnico da UERJ, Rua Alberto Rangel s/n, Nova Friburgo-RJ (Brazil); Hormaza, Joel M. [Instituto de Biociencias da UNESP, Distrito de Rubiao Junior s/n, Botucatu-SP (Brazil); Diaz, Katherin S. [CEADEN, Calle 30 502 e/5ta y 7ma Avenida, Playa, Ciudad Habana (Cuba); Lopes, Ricardo T. [Laboratorio de Instrumentacao Nuclear, COPPE, UFRJ, Rio de Janeiro-RJ (Brazil)
2010-04-15
Proton computerized tomography deals with relatively thick targets like the human head or trunk. In this case precise analytical calculation of the proton final energy is a rather complicated task, thus the Monte Carlo simulation stands out as a solution. We used the GEANT4.8.2 code to calculate the proton final energy spectra after passing a thick Al absorber and compared it with the same conditions of the experimental data. The ICRU49, Ziegler85 and Ziegler2000 models from the low energy extension pack were used. The results were also compared with the SRIM2008 and MCNPX2.4 simulations, and with solutions of the Boltzmann transport equation in the Fokker-Planck approximation.
Cousineau, Sarah M
2005-01-01
Space charge effects are a major contributor to beam halo and emittance growth leading to beam loss in high intensity, low energy accelerators. As future accelerators strive towards unprecedented levels of beam intensity and beam loss control, a more comprehensive understanding of space charge effects is required. A wealth of simulation tools have been developed for modeling beams in linacs and rings, and with the growing availability of high-speed computing systems, computationally expensive problems that were inconceivable a decade ago are now being handled with relative ease. This has opened the field for realistic simulations of space charge effects, including detailed benchmarks with experimental data. A great deal of effort is being focused in this direction, and several recent benchmark studies have produced remarkably successful results. This paper reviews the achievements in space charge benchmarking in the last few years, and discusses the challenges that remain.
International Nuclear Information System (INIS)
Traore, Ph; Daaboul, M; Louste, Ch
2010-01-01
In this paper a comparative study between numerical and experimental results from particle image velocimetry (PIV) measurements is presented in the case of two-dimensional electrohydrodynamic plumes that arise when a sharp metallic blade, submerged in non-conducting liquids, supports a high electric potential. Experiments and numerical simulations have been conducted in order to compare both the approaches. Very good agreement has been found through velocity profiles and velocity fields which proves the relevance of our numerical model. For high potentials the jet flow issued forth from the blade becomes unsteady and starts to flap on the vertical wall. Some snapshots of the temporal evolution of the isocontours of charge density which is not accessible from experiment are presented thanks to the numerical simulation.
Simulation-based optimal Bayesian experimental design for nonlinear systems
Huan, Xun; Marzouk, Youssef M.
2013-01-01
The optimal selection of experimental conditions is essential to maximizing the value of data for inference and prediction, particularly in situations where experiments are time-consuming and expensive to conduct. We propose a general mathematical
An experimental and modeling study of diethyl carbonate oxidation
Nakamura, Hisashi; Curran, Henry J.; Polo-Có rdoba, Á ngel David; Pitz, William J.; Dagaut, P.; Togbé , Casimir; Sarathy, Mani; Mehl, Marco; Agudelo, John Ramiro; Bustamante, Felipe
2015-01-01
Diethyl carbonate (DEC) is an attractive biofuel that can be used to displace petroleum-derived diesel fuel, thereby reducing CO2 and particulate emissions from diesel engines. A better understanding of DEC combustion characteristics is needed to facilitate its use in internal combustion engines. Toward this goal, ignition delay times for DEC were measured at conditions relevant to internal combustion engines using a rapid compression machine (RCM) and a shock tube. The experimental conditions investigated covered a wide range of temperatures (660-1300K), a pressure of 30bar, and equivalence ratios of 0.5, 1.0 and 2.0 in air. To provide further understanding of the intermediates formed in DEC oxidation, species concentrations were measured in a jet-stirred reactor at 10atm over a temperature range of 500-1200K and at equivalence ratios of 0.5, 1.0 and 2.0. These experimental measurements were used to aid the development and validation of a chemical kinetic model for DEC.The experimental results for ignition in the RCM showed near negative temperature coefficient (NTC) behavior. Six-membered alkylperoxy radical (RO˙2) isomerizations are conventionally thought to initiate low-temperature branching reactions responsible for NTC behavior, but DEC has no such possible 6- and 7-membered ring isomerizations. However, its molecular structure allows for 5-, 8- and 9-membered ring RO˙2 isomerizations. To provide accurate rate constants for these ring structures, ab initio computations for RO˙2⇌Q˙OOH isomerization reactions were performed. These new RO˙2 isomerization rate constants have been implemented in a chemical kinetic model for DEC oxidation. The model simulations have been compared with ignition delay times measured in the RCM near the NTC region. Results of the simulation were also compared with experimental results for ignition in the high-temperature region and for species concentrations in the jet-stirred reactor. Chemical kinetic insights into the
An experimental and modeling study of diethyl carbonate oxidation
Nakamura, Hisashi
2015-04-01
Diethyl carbonate (DEC) is an attractive biofuel that can be used to displace petroleum-derived diesel fuel, thereby reducing CO2 and particulate emissions from diesel engines. A better understanding of DEC combustion characteristics is needed to facilitate its use in internal combustion engines. Toward this goal, ignition delay times for DEC were measured at conditions relevant to internal combustion engines using a rapid compression machine (RCM) and a shock tube. The experimental conditions investigated covered a wide range of temperatures (660-1300K), a pressure of 30bar, and equivalence ratios of 0.5, 1.0 and 2.0 in air. To provide further understanding of the intermediates formed in DEC oxidation, species concentrations were measured in a jet-stirred reactor at 10atm over a temperature range of 500-1200K and at equivalence ratios of 0.5, 1.0 and 2.0. These experimental measurements were used to aid the development and validation of a chemical kinetic model for DEC.The experimental results for ignition in the RCM showed near negative temperature coefficient (NTC) behavior. Six-membered alkylperoxy radical (RO˙2) isomerizations are conventionally thought to initiate low-temperature branching reactions responsible for NTC behavior, but DEC has no such possible 6- and 7-membered ring isomerizations. However, its molecular structure allows for 5-, 8- and 9-membered ring RO˙2 isomerizations. To provide accurate rate constants for these ring structures, ab initio computations for RO˙2⇌Q˙OOH isomerization reactions were performed. These new RO˙2 isomerization rate constants have been implemented in a chemical kinetic model for DEC oxidation. The model simulations have been compared with ignition delay times measured in the RCM near the NTC region. Results of the simulation were also compared with experimental results for ignition in the high-temperature region and for species concentrations in the jet-stirred reactor. Chemical kinetic insights into the
International Nuclear Information System (INIS)
Hassan, M.A.; Naderi, S.; Bushroa, A.R.
2014-01-01
Highlights: • Low-velocity impact test on GFRP with different energy levels and thicknesses. • Using force–deflection curve to determine critical energy for penetration threshold. • Reflection of damage processes to different type of diagrams. • Significant influence of Initial energy and thickness on dynamic response of plates. • Good agreements between experimental and FEM models for the force history data. - Abstract: This paper addresses the response of Glass Fiber Reinforced Plastic laminates (GFRPs) under low-velocity impact. Experimental tests were performed according to ASTM: D5628 for different initial impact energy levels ranging from 9.8 J to 29.4 J and specimen thicknesses of 2, 3 and 4 mm. The impact damage process and contact stiffness were studied incrementally until a perforation phase of the layered compounds occurred, in line with a force–deflection diagram and imaging of impacted laminates. The influence that impact parameters such as velocity and initial energy had on deflection and damage of the test specimens was investigated. Finite Element Simulation (FES) was done using MSC. MARC® was additionally carried out to understand the impact mechanism and correlation between these parameters and the induced damage. The simulation and experimental results reached good accord regarding maximum contact force and contact time with insignificant amount of damage
Large Eddy Simulations and Experimental Investigation of Flow in a Swirl Stabilized Combustor
Kewlani, Gaurav
2012-01-09
Swirling flows are the preferred mode of flame stabilization in lean premixed gas turbine engine combustors. Developing a fundamental understanding of combustion dynamics and flame stability in such systems requires a detailed investigation of the complex interactions between fluid mechanics and combustion. The turbulent reacting flow in a sudden expansion swirl combustor is studied using compressible large eddy simulations (LES) and compared with experimental data measured using PIV. Different vortex breakdown structures are observed, as the mixture equivalence ratio is reduced, that progressively diminish the stability of the flame. Sub-grid scale combustion models such as the artificially thickened flame method and the partially stirred reactor approach, along with appropriate chemical schemes, are implemented to describe the flame. The numerical predictions for average velocity correspond well with experimental results, and higher accuracy is obtained using the more detailed reaction mechanism. Copyright © 2012 American Institute of Aeronautics and Astronautics, Inc.
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
Validation of a Wave-Body Interaction Model by Experimental Tests
DEFF Research Database (Denmark)
Ferri, Francesco; Kramer, Morten; Pecher, Arthur
2013-01-01
Within the wave energy field, numerical simulation has recently acquired a worldwide consent as being a useful tool, besides physical model testing. The main goal of this work is the validation of a numerical model by experimental results. The numerical model is based on a linear wave-body intera...
A unified mobility model for quantum mechanical simulation of MOSFETs
International Nuclear Information System (INIS)
Park, Ji Sun; Lee, Ji Young; Lee, Sang Kyung; Shin, Hyung Soon; Jin, Seong Hoon; Park, Young June; Min, Hong Shik
2004-01-01
A unified electron and hole mobility model for inversion and accumulation layers with quantum effect is presented for the first time. By accounting for the screened Coulomb scattering based on the well-known bulk mobility model and allowing the surface roughness scattering term to be a function of net charge, the new model is applicable to the bulk, inversion, and accumulation layers with only one set of fitting parameters. The new model is implemented in the 2-D quantum mechanical device simulator and gives excellent agreement with the experimentally measured effective mobility data over a wide range of effective transverse field, substrate doping, substrate bias, and temperature.
Computer Based Modelling and Simulation
Indian Academy of Sciences (India)
GENERAL I ARTICLE. Computer Based ... universities, and later did system analysis, ... sonal computers (PC) and low cost software packages and tools. They can serve as useful learning experience through student projects. Models are .... Let us consider a numerical example: to calculate the velocity of a trainer aircraft ...
Thermal unit availability modeling in a regional simulation model
International Nuclear Information System (INIS)
Yamayee, Z.A.; Port, J.; Robinett, W.
1983-01-01
The System Analysis Model (SAM) developed under the umbrella of PNUCC's System Analysis Committee is capable of simulating the operation of a given load/resource scenario. This model employs a Monte-Carlo simulation to incorporate uncertainties. Among uncertainties modeled is thermal unit availability both for energy simulation (seasonal) and capacity simulations (hourly). This paper presents the availability modeling in the capacity and energy models. The use of regional and national data in deriving the two availability models, the interaction between the two and modifications made to the capacity model in order to reflect regional practices is presented. A sample problem is presented to show the modification process. Results for modeling a nuclear unit using NERC-GADS is presented
Plasma disruption modeling and simulation
International Nuclear Information System (INIS)
Hassanein, A.
1994-01-01
Disruptions in tokamak reactors are considered a limiting factor to successful operation and reliable design. The behavior of plasma-facing components during a disruption is critical to the overall integrity of the reactor. Erosion of plasma facing-material (PFM) surfaces due to thermal energy dump during the disruption can severely limit the lifetime of these components and thus diminish the economic feasibility of the reactor. A comprehensive understanding of the interplay of various physical processes during a disruption is essential for determining component lifetime and potentially improving the performance of such components. There are three principal stages in modeling the behavior of PFM during a disruption. Initially, the incident plasma particles will deposit their energy directly on the PFM surface, heating it to a very high temperature where ablation occurs. Models for plasma-material interactions have been developed and used to predict material thermal evolution during the disruption. Within a few microseconds after the start of the disruption, enough material is vaporized to intercept most of the incoming plasma particles. Models for plasma-vapor interactions are necessary to predict vapor cloud expansion and hydrodynamics. Continuous heating of the vapor cloud above the material surface by the incident plasma particles will excite, ionize, and cause vapor atoms to emit thermal radiation. Accurate models for radiation transport in the vapor are essential for calculating the net radiated flux to the material surface which determines the final erosion thickness and consequently component lifetime. A comprehensive model that takes into account various stages of plasma-material interaction has been developed and used to predict erosion rates during reactor disruption, as well during induced disruption in laboratory experiments
Experimental study and modelling of iron ore reduction by hydrogen
International Nuclear Information System (INIS)
Wagner, D.
2008-01-01
In an effort to find new ways to drastically reduce the CO 2 emissions from the steel industry (ULCOS project), the reduction of iron ore by pure hydrogen in a shaft furnace was investigated. The work consisted of literature, experimental, and modelling studies. The chemical reaction and its kinetics were analysed on the basis of thermogravimetric experiments and physicochemical characterizations of partially reduced samples. A specific kinetic model was designed, which simulates the successive reactions, the different steps of mass transport, and possible iron sintering, at the particle scale. Finally, a 2-dimensional numerical model of a shaft furnace was developed. It depicts the variation of the solid and gas temperatures and compositions throughout the reactor. One original feature of the model is using the law of additive characteristic times for calculating the reaction rates. This allowed us to handle both the particle and the reactor scale, while keeping reasonable calculation time. From the simulation results, the influence of the process parameters was assessed. Optimal operating conditions were concluded, which reveal the efficiency of the hydrogen process. (author)
Uterus models for use in virtual reality hysteroscopy simulators.
Niederer, Peter; Weiss, Stephan; Caduff, Rosmarie; Bajka, Michael; Szekély, Gabor; Harders, Matthias
2009-05-01
Virtual reality models of human organs are needed in surgery simulators which are developed for educational and training purposes. A simulation can only be useful, however, if the mechanical performance of the system in terms of force-feedback for the user as well as the visual representation is realistic. We therefore aim at developing a mechanical computer model of the organ in question which yields realistic force-deformation behavior under virtual instrument-tissue interactions and which, in particular, runs in real time. The modeling of the human uterus is described as it is to be implemented in a simulator for minimally invasive gynecological procedures. To this end, anatomical information which was obtained from specially designed computed tomography and magnetic resonance imaging procedures as well as constitutive tissue properties recorded from mechanical testing were used. In order to achieve real-time performance, the combination of mechanically realistic numerical uterus models of various levels of complexity with a statistical deformation approach is suggested. In view of mechanical accuracy of such models, anatomical characteristics including the fiber architecture along with the mechanical deformation properties are outlined. In addition, an approach to make this numerical representation potentially usable in an interactive simulation is discussed. The numerical simulation of hydrometra is shown in this communication. The results were validated experimentally. In order to meet the real-time requirements and to accommodate the large biological variability associated with the uterus, a statistical modeling approach is demonstrated to be useful.
Experimental Preparation and Numerical Simulation of High Thermal Conductive Cu/CNTs Nanocomposites
Directory of Open Access Journals (Sweden)
Muhsan Ali Samer
2014-07-01
Full Text Available Due to the rapid growth of high performance electronics devices accompanied by overheating problem, heat dissipater nanocomposites material having ultra-high thermal conductivity and low coefficient of thermal expansion was proposed. In this work, a nanocomposite material made of copper (Cu reinforced by multi-walled carbon nanotubes (CNTs up to 10 vol. % was prepared and their thermal behaviour was measured experimentally and evaluated using numerical simulation. In order to numerically predict the thermal behaviour of Cu/CNTs composites, three different prediction methods were performed. The results showed that rules of mixture method records the highest thermal conductivity for all predicted composites. In contrast, the prediction model which takes into account the influence of the interface thermal resistance between CNTs and copper particles, has shown the lowest thermal conductivity which considered as the closest results to the experimental measurement. The experimentally measured thermal conductivities showed remarkable increase after adding 5 vol.% CNTs and higher than the thermal conductivities predicted via Nan models, indicating that the improved fabrication technique of powder injection molding that has been used to produced Cu/CNTs nanocomposites has overcome the challenges assumed in the mathematical models.
Modelling and simulating fire tube boiler performance
DEFF Research Database (Denmark)
Sørensen, K.; Condra, T.; Houbak, Niels
2003-01-01
A model for a flue gas boiler covering the flue gas and the water-/steam side has been formulated. The model has been formulated as a number of sub models that are merged into an overall model for the complete boiler. Sub models have been defined for the furnace, the convection zone (split in 2......: a zone submerged in water and a zone covered by steam), a model for the material in the boiler (the steel) and 2 models for resp. the water/steam zone (the boiling) and the steam. The dynamic model has been developed as a number of Differential-Algebraic-Equation system (DAE). Subsequently Mat......Lab/Simulink has been applied for carrying out the simulations. To be able to verify the simulated results experiments has been carried out on a full scale boiler plant....
Numerical modelling of negative discharges in air with experimental validation
International Nuclear Information System (INIS)
Tran, T N; Golosnoy, I O; Lewin, P L; Georghiou, G E
2011-01-01
Axisymmetric finite element models have been developed for the simulation of negative discharges in air without and with the presence of dielectrics. The models are based on the hydrodynamic drift-diffusion approximation. A set of continuity equations accounting for the movement, generation and loss of charge carriers (electrons, positive and negative ions) is coupled with Poisson's equation to take into account the effect of space and surface charges on the electric field. The model of a negative corona discharge (without dielectric barriers) in a needle-plane geometry is analysed first. The results obtained show good agreement with experimental observations for various Trichel pulse characteristics. With dielectric barriers introduced into the discharge system, the surface discharge exhibits some similarities and differences to the corona case. The model studies the dynamics of volume charge generation, electric field variations and charge accumulation over the dielectric surface. The predicted surface charge density is consistent with experimental results obtained from the Pockels experiment in terms of distribution form and magnitude.
Lap weld joint modelling and simulation of welding in programme SYSWELD
Directory of Open Access Journals (Sweden)
Koňár Radoslav
2018-01-01
Full Text Available Simulations of the welding process for applications of practice using SYSWELD are presented. This paper presents simulation of welding in the repair of high-pressure gas pipeline with steel sleeve with composite filling. Material of experimental sample was steel S355. The simulations in SYSWELD divided in to two parts: the thermal simulation followed by the mechanical simulation. The results of the numerical model, which are listed in article are compared to real experiments.
An Improved Model for FE Modeling and Simulation of Closed Cell Al-Alloy Foams
Hasan, MD. Anwarul
2010-01-01
Cell wall material properties of Al-alloy foams have been derived by a combination of nanoindentation experiment and numerical simulation. Using the derived material properties in FE (finite element) modeling of foams, the existing constitutive models of closed-cell Al-alloy foams have been evaluated against experimental results. An improved representative model has been proposed for FE analysis of closed-cell Al-alloy foams. The improved model consists of a combination of spherical and cruci...
A virtual laboratory notebook for simulation models.
Winfield, A J
1998-01-01
In this paper we describe how we have adopted the laboratory notebook as a metaphor for interacting with computer simulation models. This 'virtual' notebook stores the simulation output and meta-data (which is used to record the scientist's interactions with the simulation). The meta-data stored consists of annotations (equivalent to marginal notes in a laboratory notebook), a history tree and a log of user interactions. The history tree structure records when in 'simulation' time, and from what starting point in the tree changes are made to the parameters by the user. Typically these changes define a new run of the simulation model (which is represented as a new branch of the history tree). The tree shows the structure of the changes made to the simulation and the log is required to keep the order in which the changes occurred. Together they form a record which you would normally find in a laboratory notebook. The history tree is plotted in simulation parameter space. This shows the scientist's interactions with the simulation visually and allows direct manipulation of the parameter information presented, which in turn is used to control directly the state of the simulation. The interactions with the system are graphical and usually involve directly selecting or dragging data markers and other graphical control devices around in parameter space. If the graphical manipulators do not provide precise enough control then textual manipulation is still available which allows numerical values to be entered by hand. The Virtual Laboratory Notebook, by providing interesting interactions with the visual view of the history tree, provides a mechanism for giving the user complex and novel ways of interacting with biological computer simulation models.
An Experimental Approach to Simulations of the CLIC Interaction Point
DEFF Research Database (Denmark)
Esberg, Jakob
2012-01-01
with respect to the luminosity weighted depolarization is discussed. In the chapter on muons, the implementation of the production of incoherent muons in GUINEA-PIG++ will be discussed. Comments on the correctness and completeness of the implementation of muon production will be presented. The chapter...... experiments conducted at MAMI will be presented. Furthermore the chapter discusses the performance of new CMOS based detectors to be used in future experiments by the NA63 collaboration. The chapter on collider simulations introduces the beam-beam simulation codes GUINEA-PIG and GUINEA-PIG++, their methods...... of operation and their features. The characteristics of the simulated particles are presented and a comparison between the outputs of these codes with those from CAIN. \\item In the chapter on tridents, the implementation of the direct trident process in GUINEA-PIG++ is described. The results are compared...
Turbulence modeling for Francis turbine water passages simulation
International Nuclear Information System (INIS)
Maruzewski, P; Munch, C; Mombelli, H P; Avellan, F; Hayashi, H; Yamaishi, K; Hashii, T; Sugow, Y
2010-01-01
The applications of Computational Fluid Dynamics, CFD, to hydraulic machines life require the ability to handle turbulent flows and to take into account the effects of turbulence on the mean flow. Nowadays, Direct Numerical Simulation, DNS, is still not a good candidate for hydraulic machines simulations due to an expensive computational time consuming. Large Eddy Simulation, LES, even, is of the same category of DNS, could be an alternative whereby only the small scale turbulent fluctuations are modeled and the larger scale fluctuations are computed directly. Nevertheless, the Reynolds-Averaged Navier-Stokes, RANS, model have become the widespread standard base for numerous hydraulic machine design procedures. However, for many applications involving wall-bounded flows and attached boundary layers, various hybrid combinations of LES and RANS are being considered, such as Detached Eddy Simulation, DES, whereby the RANS approximation is kept in the regions where the boundary layers are attached to the solid walls. Furthermore, the accuracy of CFD simulations is highly dependent on the grid quality, in terms of grid uniformity in complex configurations. Moreover any successful structured and unstructured CFD codes have to offer a wide range to the variety of classic RANS model to hybrid complex model. The aim of this study is to compare the behavior of turbulent simulations for both structured and unstructured grids topology with two different CFD codes which used the same Francis turbine. Hence, the study is intended to outline the encountered discrepancy for predicting the wake of turbine blades by using either the standard k-ε model, or the standard k-ε model or the SST shear stress model in a steady CFD simulation. Finally, comparisons are made with experimental data from the EPFL Laboratory for Hydraulic Machines reduced scale model measurements.
Turbulence modeling for Francis turbine water passages simulation
Energy Technology Data Exchange (ETDEWEB)
Maruzewski, P; Munch, C; Mombelli, H P; Avellan, F [Ecole polytechnique federale de Lausanne, Laboratory of Hydraulic Machines Avenue de Cour 33 bis, CH-1007 Lausanne (Switzerland); Hayashi, H; Yamaishi, K; Hashii, T; Sugow, Y, E-mail: pierre.maruzewski@epfl.c [Nippon KOEI Power Systems, 1-22 Doukyu, Aza, Morijyuku, Sukagawa, Fukushima Pref. 962-8508 (Japan)
2010-08-15
The applications of Computational Fluid Dynamics, CFD, to hydraulic machines life require the ability to handle turbulent flows and to take into account the effects of turbulence on the mean flow. Nowadays, Direct Numerical Simulation, DNS, is still not a good candidate for hydraulic machines simulations due to an expensive computational time consuming. Large Eddy Simulation, LES, even, is of the same category of DNS, could be an alternative whereby only the small scale turbulent fluctuations are modeled and the larger scale fluctuations are computed directly. Nevertheless, the Reynolds-Averaged Navier-Stokes, RANS, model have become the widespread standard base for numerous hydraulic machine design procedures. However, for many applications involving wall-bounded flows and attached boundary layers, various hybrid combinations of LES and RANS are being considered, such as Detached Eddy Simulation, DES, whereby the RANS approximation is kept in the regions where the boundary layers are attached to the solid walls. Furthermore, the accuracy of CFD simulations is highly dependent on the grid quality, in terms of grid uniformity in complex configurations. Moreover any successful structured and unstructured CFD codes have to offer a wide range to the variety of classic RANS model to hybrid complex model. The aim of this study is to compare the behavior of turbulent simulations for both structured and unstructured grids topology with two different CFD codes which used the same Francis turbine. Hence, the study is intended to outline the encountered discrepancy for predicting the wake of turbine blades by using either the standard k-{epsilon} model, or the standard k-{epsilon} model or the SST shear stress model in a steady CFD simulation. Finally, comparisons are made with experimental data from the EPFL Laboratory for Hydraulic Machines reduced scale model measurements.
Turbulence modeling for Francis turbine water passages simulation
Maruzewski, P.; Hayashi, H.; Munch, C.; Yamaishi, K.; Hashii, T.; Mombelli, H. P.; Sugow, Y.; Avellan, F.
2010-08-01
The applications of Computational Fluid Dynamics, CFD, to hydraulic machines life require the ability to handle turbulent flows and to take into account the effects of turbulence on the mean flow. Nowadays, Direct Numerical Simulation, DNS, is still not a good candidate for hydraulic machines simulations due to an expensive computational time consuming. Large Eddy Simulation, LES, even, is of the same category of DNS, could be an alternative whereby only the small scale turbulent fluctuations are modeled and the larger scale fluctuations are computed directly. Nevertheless, the Reynolds-Averaged Navier-Stokes, RANS, model have become the widespread standard base for numerous hydraulic machine design procedures. However, for many applications involving wall-bounded flows and attached boundary layers, various hybrid combinations of LES and RANS are being considered, such as Detached Eddy Simulation, DES, whereby the RANS approximation is kept in the regions where the boundary layers are attached to the solid walls. Furthermore, the accuracy of CFD simulations is highly dependent on the grid quality, in terms of grid uniformity in complex configurations. Moreover any successful structured and unstructured CFD codes have to offer a wide range to the variety of classic RANS model to hybrid complex model. The aim of this study is to compare the behavior of turbulent simulations for both structured and unstructured grids topology with two different CFD codes which used the same Francis turbine. Hence, the study is intended to outline the encountered discrepancy for predicting the wake of turbine blades by using either the standard k-epsilon model, or the standard k-epsilon model or the SST shear stress model in a steady CFD simulation. Finally, comparisons are made with experimental data from the EPFL Laboratory for Hydraulic Machines reduced scale model measurements.
International Nuclear Information System (INIS)
Zhu Dingqiang; Shen Wentao; Cai Guobiao; Ke Weina
2013-01-01
The optical properties of a spatial target are important characteristics for its detection, identification, tracking and interception. A homeostatic model of the temperature and infrared characteristics of the target has been developed considering the radiation of the environmental background. The heat conduction inside the wall and the effect of an internal heat source are included in the model. The reflection characteristics of the target are calculated with bi-directional reflection distribution function (BRDF) models. The temperature and infrared radiation have been measured in the simulating space environment in the ground tests. The comparisons between the theoretical results and experimental data demonstrate a good agreement. Applying the developed model, the influences of several parameters (such as spin frequency, absorptivity/emissivity and thermal conductivity) of the target have been investigated. Highlights: ► A mathematical model was developed to predict the optical characteristics of a spatial target. ► The temperature and infrared radiation are measured in ground tests. ► The simulation results and the test results are consistent. ► The effects of several target parameters were analysed.
Experimental Characterization and Modeling of PEM Fuel Cells
DEFF Research Database (Denmark)
Jespersen, Jesper Lebæk
fundamental knowledge of the transport and electrochemical processes of PEM fuel cells and to provide methods for obtaining high quality data for PEM fuel cell simulation model validation. In this thesis three different areas of experimental characterization techniques was investigated, they include: Stack...... for obtaining very detailed data of the manifold flow. Moreover, the tools complement each other well, as high quality validation data can be obtained from PIV measurements to verify CFD models. AC Impedance Spectroscopy was used to thoroughly characterize a HTPEM single cell. The measurement method...... was furthermore transferred onto a Labview platform, which signiffcantly improves the exibility and lowers the cost of using this method. This technique is expected to bea very important future tool, used both for material characterization, celldiagnostic, system optimization and as a control input parameter...
Modeling and Simulation of Claus Unit Reaction Furnace
Directory of Open Access Journals (Sweden)
Maryam Pahlavan
2016-01-01
Full Text Available Reaction furnace is the most important part of the Claus sulfur recovery unit and its performance has a significant impact on the process efficiency. Too many reactions happen in the furnace and their kinetics and mechanisms are not completely understood; therefore, modeling reaction furnace is difficult and several works have been carried out on in this regard so far. Equilibrium models are commonly used to simulate the furnace, but the related literature states that the outlet of furnace is not in equilibrium and the furnace reactions are controlled by kinetic laws; therefore, in this study, the reaction furnace is simulated by a kinetic model. The predicted outlet temperature and concentrations by this model are compared with experimental data published in the literature and the data obtained by PROMAX V2.0 simulator. The results show that the accuracy of the proposed kinetic model and PROMAX simulator is almost similar, but the kinetic model used in this paper has two importance abilities. Firstly, it is a distributed model and can be used to obtain the temperature and concentration profiles along the furnace. Secondly, it is a dynamic model and can be used for analyzing the transient behavior and designing the control system.
Polarimetric Emission of Rain Events: Simulation and Experimental Results at X-Band
Directory of Open Access Journals (Sweden)
Nuria Duffo
2009-06-01
Full Text Available Accurate models are used today for infrared and microwave satellite radiance simulations of the first two Stokes elements in the physical retrieval, data assimilation etc. of surface and atmospheric parameters. Although in the past a number of theoretical and experimental works have studied the polarimetric emission of some natural surfaces, specially the sea surface roughened by the wind (Windsat mission, very limited studies have been conducted on the polarimetric emission of rain cells or other natural surfaces. In this work, the polarimetric emission (four Stokes elements of a rain cell is computed using the polarimetric radiative transfer equation assuming that raindrops are described by Pruppacher-Pitter shapes and that their size distribution follows the Laws-Parsons law. The Boundary Element Method (BEM is used to compute the exact bistatic scattering coefficients for each raindrop shape and different canting angles. Numerical results are compared to the Rayleigh or Mie scattering coefficients, and to Oguchi’s ones, showing that above 1-2 mm raindrop size the exact formulation is required to model properly the scattering. Simulation results using BEM are then compared to the experimental data gathered with a X-band polarimetric radiometer. It is found that the depolarization of the radiation caused by the scattering of non-spherical raindrops induces a non-zero third Stokes parameter, and the differential phase of the scattering coefficients induces a non-zero fourth Stokes parameter.
International Nuclear Information System (INIS)
Grossetete, Claudie
1995-01-01
We present here an experimental investigation and some numerical simulations of void profile development in a vertical cylindrical pipe. This study is motivated by the lack of information dealing with the influence of entrance effects and bubble size evolution upon the multidimensional development of upward bubbly flow in pipe. The axial development of two-phase air-water upward bubbly and bubbly-to-slug transition flows in a vertical pipe is investigated experimentally first. Profiles of liquid mean velocity, liquid axial turbulent intensity, void fraction, bubble frequency, bubble velocity, mean equivalent bubble diameter and volumetric interfacial area are determined along the same test section at three axial locations. It is found that the bubbly-to-slug transition can be deduced from the simultaneous analysis of the different measured profiles. Local analysis of the studied bubbly flows shows that their development does not depend on the shape of the void distribution at the inlet. However, it is found that the bubble size evolution strongly affects the void distribution. Secondly, multidimensional numerical simulations of bubbly flows with very different gas injection modes are made with the help of the tri dimensional two-fluid ASTRID code. It is shown that the classical models used to close the transverse momentum equations of the two-fluid model (lift and dispersion forces) do not capture the physical phenomena of bubble migration in pipe flows. (author) [fr
International Nuclear Information System (INIS)
Grossetete, C.
1995-12-01
We present here an experimental investigation and some numerical simulations of void profile development in a vertical cylindrical pipe. This study is motivated by the lack of information dealing with the influence of entrance effects and bubble size evolution upon the multidimensional development of upward bubbly flow in pipe. The axial development of two-phase air-water upward bubbly and bubbly-to-slug transition flows in a vertical pipe is investigated experimentally first. Profiles of liquid mean velocity, liquid axial turbulent intensity, void fraction, bubble frequency, bubble velocity, mean equivalent bubble diameter and volumetric interfacial area are determined along the same test section at three axial locations. It is found that the bubbly-to-slug transition can be deduced from the simultaneous analysis of the different measured profiles. Local analysis of the studied bubbly flows shows that their development does not depend on the shape of the void distribution at the inlet. However, it is found that the bubble size evolution strongly affects the void distribution. Secondly, multidimensional numerical simulations of bubbly flows with very different gas injection modes are made with the help of the tridimensional two-fluid ASTRID code. It is shown that the classical models used to close the transverse momentum equations of the two-fluid model (lift and dispersion forces) do not capture the physical phenomena of bubble migration in pipe flows
International Nuclear Information System (INIS)
Magnoli, M V; Maiwald, M
2014-01-01
Francis turbines have been running more and more frequently in part load conditions, in order to satisfy the new market requirements for more dynamic and flexible energy generation, ancillary services and grid regulation. The turbines should be able to be operated for longer durations with flows below the optimum point, going from part load to deep part load and even speed-no-load. These operating conditions are characterised by important unsteady flow phenomena taking place at the draft tube cone and in the runner channels, in the respective cases of part load and deep part load. The current expectations are that new Francis turbines present appropriate hydraulic stability and moderate pressure pulsations at overload, part load, deep part load and speed-no-load with high efficiency levels at normal operating range. This study presents series of investigations performed by Voith Hydro with the objective to improve the hydraulic stability of Francis turbines at overload, part load and deep part load, reduce pressure pulsations and enlarge the know-how about the transient fluid flow through the turbine at these challenging conditions. Model test measurements showed that distinct runner designs were able to influence the pressure pulsation level in the machine. Extensive experimental investigations focused on the runner deflector geometry, on runner features and how they could reduce the pressure oscillation level. The impact of design variants and machine configurations on the vortex rope at the draft tube cone at overload and part load and on the runner channel vortex at deep part load were experimentally observed and evaluated based on the measured pressure pulsation amplitudes. Numerical investigations were employed for improving the understanding of such dynamic fluid flow effects. As example for the design and experimental investigations, model test observations and pressure pulsation curves for Francis machines in mid specific speed range, around n qopt = 50
Dynamic Simulation of Human Gait Model With Predictive Capability.
Sun, Jinming; Wu, Shaoli; Voglewede, Philip A
2018-03-01
In this paper, it is proposed that the central nervous system (CNS) controls human gait using a predictive control approach in conjunction with classical feedback control instead of exclusive classical feedback control theory that controls based on past error. To validate this proposition, a dynamic model of human gait is developed using a novel predictive approach to investigate the principles of the CNS. The model developed includes two parts: a plant model that represents the dynamics of human gait and a controller that represents the CNS. The plant model is a seven-segment, six-joint model that has nine degrees-of-freedom (DOF). The plant model is validated using data collected from able-bodied human subjects. The proposed controller utilizes model predictive control (MPC). MPC uses an internal model to predict the output in advance, compare the predicted output to the reference, and optimize the control input so that the predicted error is minimal. To decrease the complexity of the model, two joints are controlled using a proportional-derivative (PD) controller. The developed predictive human gait model is validated by simulating able-bodied human gait. The simulation results show that the developed model is able to simulate the kinematic output close to experimental data.
MODELLING, SIMULATING AND OPTIMIZING BOILERS
DEFF Research Database (Denmark)
Sørensen, K.; Condra, T.; Houbak, Niels
2003-01-01
, and the total stress level (i.e. stresses introduced due to internal pressure plus stresses introduced due to temperature gradients) must always be kept below the allowable stress level. In this way, the increased water-/steam space that should allow for better dynamic performance, in the end causes limited...... freedom with respect to dynamic operation of the plant. By means of an objective function including as well the price of the plant as a quantification of the value of dynamic operation of the plant an optimization is carried out. The dynamic model of the boiler plant is applied to define parts...
Signal Simulation and Experimental Research on Acoustic Emission using LS-DYNA
Directory of Open Access Journals (Sweden)
Zhang Jianchao
2015-09-01
Full Text Available To calculate sound wave velocity, we performed the Hsu-Nielsen lead break experiment using the ANSYS/LS-DYNA finite element software. First, we identified the key problems in the finite element analysis, such as selecting the exciting force, dividing the grid density, and setting the calculation steps. Second, we established the finite element model of the sound wave transmission in a plate under the lead break simulation. Results revealed not only the transmission characteristics of the sound wave but also the simulation and calculation of the transmission velocity of the longitudinal and transverse waves through the time travel curve of the vibration velocity of the sound wave at various nodes. Finally, the Hsu-Nielsen lead break experiment was implemented. The results of the theoretical calculation and simulation analysis were consistent with the experimental results, thus demonstrating that the research method using the ANSYS/LS-DYNA software to simulate sound wave transmissions in acoustic emission experiments is feasible and effective.
Liu, Z; Voelger, P; Sugimoto, N
2000-06-20
We carried out a simulation study for the observation of clouds and aerosols with the Japanese Experimental Lidar in Space Equipment (ELISE), which is a two-wavelength backscatter lidar with three detection channels. The National Space Development Agency of Japan plans to launch the ELISE on the Mission Demonstrate Satellite 2 (MDS-2). In the simulations, the lidar return signals for the ELISE are calculated for an artificial, two-dimensional atmospheric model including different types of clouds and aerosols. The signal detection processes are simulated realistically by inclusion of various sources of noise. The lidar signals that are generated are then used as input for simulations of data analysis with inversion algorithms to investigate retrieval of the optical properties of clouds and aerosols. The results demonstrate that the ELISE can provide global data on the structures and optical properties of clouds and aerosols. We also conducted an analysis of the effects of cloud inhomogeneity on retrievals from averaged lidar profiles. We show that the effects are significant for space lidar observations of optically thick broken clouds.
Dobson, Patrick F.; Kneafsey, Timothy J.; Sonnenthal, Eric L.; Spycher, Nicolas; Apps, John A.
2003-05-01
, differences in fluid flow rates and thermal gradients between the experimental setup and anticipated conditions at Yucca Mountain need to be factored into scaling the results of the dissolution/precipitation experiments and associated simulations to THC models for the potential Yucca Mountain repository.
Demonstration of theoretical and experimental simulations in fiber optics course
Yao, Tianfu; Wang, Xiaolin; Shi, Jianhua; Lei, Bing; Liu, Wei; Wang, Wei; Hu, Haojun
2017-08-01
"Fiber optics" course plays a supporting effect in the curriculum frame of optics and photonics at both undergraduate and postgraduate levels. Moreover, the course can be treated as compulsory for students specialized in the fiber-related field, such as fiber communication, fiber sensing and fiber light source. The corresponding content in fiber optics requires the knowledge of geometrical and physical optics as background, including basic optical theory and fiber components in practice. Thus, to help the students comprehend the relatively abundant and complex content, it is necessary to investigate novel teaching method assistant the classic lectures. In this paper, we introduce the multidimensional pattern in fiber-optics teaching involving theoretical and laboratory simulations. First, the theoretical simulations is demonstrated based on the self-developed software named "FB tool" which can be installed in both smart phone with Android operating system and personal computer. FB tool covers the fundamental calculations relating to transverse modes, fiber lasers and nonlinearities and so on. By comparing the calculation results with other commercial software like COMSOL, SFTool shows high accuracy with high speed. Then the laboratory simulations are designed including fiber coupling, Erbium doped fiber amplifiers, fiber components and so on. The simulations not only supports students understand basic knowledge in the course, but also provides opportunities to develop creative projects in fiber optics.
Experimental simulation of the natural transformation of kerogen
Energy Technology Data Exchange (ETDEWEB)
Monin, J C [Institut Francais du Petrole, Rueil-Malmaison, France; Durand, B; Vandenbroucke, M; Huc, A Y
1980-01-01
Analytical techniques such as elemental analysis, infrared spectroscopy, ESR, dark-field electron microscopy and reflectance analysis applied to kerogens enables the geochemist to describe how they evolve at depth. Simulation of this evolution is obtained by the temperature-programmed heating of immature samples in a stream of inert gas. Comparison of naturally occurring samples at increasing stages of maturation, and artificially matured samples demonstrates that this simulation generally reproduces the overall characteristics of evolution at depth. However, agreement is better for hydrogen-rich than for oxygen-rich kerogens. In fact, oxygen is eliminated in nature, and in the laboratory, by different mechanisms. In nature, elimination takes place mainly at the beginning of burial. Temperatures used in the laboratory are necessarily much higher and appear to cause secondary reactions which favor water formation. Elimination of hydrogen occurs, during natural maturation, at greater depths and temperatures - i.e., in the oil and gas formation zone. Therefore, laboratory simulation is better for kerogens which have already reached the oil formation stage. Hydrocarbons released by natural and laboratory-simulated maturation are compared. Although quantities and distributions are different, similarities exist which can be used, to a first approximation, to predict the distribution of hydrocarbons obtained from naturally-evolving kerogens.
Advanced training simulator models. Implementation and validation
International Nuclear Information System (INIS)
Borkowsky, Jeffrey; Judd, Jerry; Belblidia, Lotfi; O'farrell, David; Andersen, Peter
2008-01-01
Modern training simulators are required to replicate plant data for both thermal-hydraulic and neutronic response. Replication is required such that reactivity manipulation on the simulator properly trains the operator for reactivity manipulation at the plant. This paper discusses advanced models which perform this function in real-time using the coupled code system THOR/S3R. This code system models the all fluids systems in detail using an advanced, two-phase thermal-hydraulic a model. The nuclear core is modeled using an advanced, three-dimensional nodal method and also by using cycle-specific nuclear data. These models are configured to run interactively from a graphical instructor station or handware operation panels. The simulator models are theoretically rigorous and are expected to replicate the physics of the plant. However, to verify replication, the models must be independently assessed. Plant data is the preferred validation method, but plant data is often not available for many important training scenarios. In the absence of data, validation may be obtained by slower-than-real-time transient analysis. This analysis can be performed by coupling a safety analysis code and a core design code. Such a coupling exists between the codes RELAP5 and SIMULATE-3K (S3K). RELAP5/S3K is used to validate the real-time model for several postulated plant events. (author)
Regularization modeling for large-eddy simulation
Geurts, Bernardus J.; Holm, D.D.
2003-01-01
A new modeling approach for large-eddy simulation (LES) is obtained by combining a "regularization principle" with an explicit filter and its inversion. This regularization approach allows a systematic derivation of the implied subgrid model, which resolves the closure problem. The central role of
Analytical system dynamics modeling and simulation
Fabien, Brian C
2008-01-01
This book offering a modeling technique based on Lagrange's energy method includes 125 worked examples. Using this technique enables one to model and simulate systems as diverse as a six-link, closed-loop mechanism or a transistor power amplifier.
Hybrid simulation models of production networks
Kouikoglou, Vassilis S
2001-01-01
This book is concerned with a most important area of industrial production, that of analysis and optimization of production lines and networks using discrete-event models and simulation. The book introduces a novel approach that combines analytic models and discrete-event simulation. Unlike conventional piece-by-piece simulation, this method observes a reduced number of events between which the evolution of the system is tracked analytically. Using this hybrid approach, several models are developed for the analysis of production lines and networks. The hybrid approach combines speed and accuracy for exceptional analysis of most practical situations. A number of optimization problems, involving buffer design, workforce planning, and production control, are solved through the use of hybrid models.
Dynamic modeling and simulation of wind turbines
International Nuclear Information System (INIS)
Ghafari Seadat, M.H.; Kheradmand Keysami, M.; Lari, H.R.
2002-01-01
Using wind energy for generating electricity in wind turbines is a good way for using renewable energies. It can also help to protect the environment. The main objective of this paper is dynamic modeling by energy method and simulation of a wind turbine aided by computer. In this paper, the equations of motion are extracted for simulating the system of wind turbine and then the behavior of the system become obvious by solving the equations. The turbine is considered with three blade rotor in wind direction, induced generator that is connected to the network and constant revolution for simulation of wind turbine. Every part of the wind turbine should be simulated for simulation of wind turbine. The main parts are blades, gearbox, shafts and generator
International Nuclear Information System (INIS)
Clifford, Corey E.; Kimber, Mark L.
2015-01-01
Although computational fluid dynamics (CFD) has not been directly utilized to perform safety analyses of nuclear reactors in the United States, several vendors are considering adopting commercial numerical packages for current and future projects. To ensure the accuracy of these computational models, it is imperative to validate the assumptions and approximations built into commercial CFD codes against physical data from flows analogous to those in modern nuclear reactors. To this end, researchers at Utah State University (USU) have constructed the Rotatable Buoyancy Tunnel (RoBuT) test facility, which is designed to provide flow and thermal validation data for CFD simulations of forced and mixed convection scenarios. In order to evaluate the ability of current CFD codes to capture the complex physics associated with these types of flows, a computational model of the RoBuT test facility is created using the ANSYS Fluent commercial CFD code. The numerical RoBuT model is analyzed at identical conditions to several experimental trials undertaken at USU. Each experiment is reconstructed numerically and evaluated with the second-order Reynolds stress model (RSM). Two different thermal boundary conditions at the heated surface of the RoBuT test section are investigated: constant temperature (isothermal) and constant surface heat flux (isoflux). Additionally, the fluid velocity at the inlet of the test section is varied in an effort to modify the relative importance of natural convection heat transfer from the heated wall of the RoBuT. Mean velocity, both in the streamwise and transverse directions, as well as components of the Reynolds stress tensor at three points downstream of the RoBuT test section inlet are compared to results obtained from experimental trials. Early computational results obtained from this research initiative are in good agreement with experimental data obtained from the RoBuT facility and both the experimental data and numerical method can be used
Deterministic modelling and stochastic simulation of biochemical pathways using MATLAB.
Ullah, M; Schmidt, H; Cho, K H; Wolkenhauer, O
2006-03-01
The analysis of complex biochemical networks is conducted in two popular conceptual frameworks for modelling. The deterministic approach requires the solution of ordinary differential equations (ODEs, reaction rate equations) with concentrations as continuous state variables. The stochastic approach involves the simulation of differential-difference equations (chemical master equations, CMEs) with probabilities as variables. This is to generate counts of molecules for chemical species as realisations of random variables drawn from the probability distribution described by the CMEs. Although there are numerous tools available, many of them free, the modelling and simulation environment MATLAB is widely used in the physical and engineering sciences. We describe a collection of MATLAB functions to construct and solve ODEs for deterministic simulation and to implement realisations of CMEs for stochastic simulation using advanced MATLAB coding (Release 14). The program was successfully applied to pathway models from the literature for both cases. The results were compared to implementations using alternative tools for dynamic modelling and simulation of biochemical networks. The aim is to provide a concise set of MATLAB functions that encourage the experimentation with systems biology models. All the script files are available from www.sbi.uni-rostock.de/ publications_matlab-paper.html.
Directory of Open Access Journals (Sweden)
R. Fargère
2012-01-01
Full Text Available Some interactions between the dynamic and tribological behaviour of geared transmissions are examined, and a number of experimental and simulation results are compared. A model is introduced which incorporates most of the possible interactions between gears, shafts and hydrodynamic journal bearings. It combines (i a specific element for wide-faced gears that includes the normal contact conditions between actual mating teeth, that is, with tooth shape deviations and mounting errors, (ii shaft finite elements, and (iii the external forces generated by journal bearings determined by directly solving Reynolds' equation. The simulation results are compared with the measurement obtained on a high-precision test rig with single-stage spur and helical gears supported by hydrodynamic journal bearings. The experimental and simulation results compare well thus validating the simulation strategy both at the global and local scales.
Regional model simulations of New Zealand climate
Renwick, James A.; Katzfey, Jack J.; Nguyen, Kim C.; McGregor, John L.
1998-03-01
Simulation of New Zealand climate is examined through the use of a regional climate model nested within the output of the Commonwealth Scientific and Industrial Research Organisation nine-level general circulation model (GCM). R21 resolution GCM output is used to drive a regional model run at 125 km grid spacing over the Australasian region. The 125 km run is used in turn to drive a simulation at 50 km resolution over New Zealand. Simulations with a full seasonal cycle are performed for 10 model years. The focus is on the quality of the simulation of present-day climate, but results of a doubled-CO2 run are discussed briefly. Spatial patterns of mean simulated precipitation and surface temperatures improve markedly as horizontal resolution is increased, through the better resolution of the country's orography. However, increased horizontal resolution leads to a positive bias in precipitation. At 50 km resolution, simulated frequency distributions of daily maximum/minimum temperatures are statistically similar to those of observations at many stations, while frequency distributions of daily precipitation appear to be statistically different to those of observations at most stations. Modeled daily precipitation variability at 125 km resolution is considerably less than observed, but is comparable to, or exceeds, observed variability at 50 km resolution. The sensitivity of the simulated climate to changes in the specification of the land surface is discussed briefly. Spatial patterns of the frequency of extreme temperatures and precipitation are generally well modeled. Under a doubling of CO2, the frequency of precipitation extremes changes only slightly at most locations, while air frosts become virtually unknown except at high-elevation sites.
Landscape Modelling and Simulation Using Spatial Data
Directory of Open Access Journals (Sweden)
Amjed Naser Mohsin AL-Hameedawi
2017-08-01
Full Text Available In this paper a procedure was performed for engendering spatial model of landscape acclimated to reality simulation. This procedure based on combining spatial data and field measurements with computer graphics reproduced using Blender software. Thereafter that we are possible to form a 3D simulation based on VIS ALL packages. The objective was to make a model utilising GIS, including inputs to the feature attribute data. The objective of these efforts concentrated on coordinating a tolerable spatial prototype, circumscribing facilitation scheme and outlining the intended framework. Thus; the eventual result was utilized in simulation form. The performed procedure contains not only data gathering, fieldwork and paradigm providing, but extended to supply a new method necessary to provide the respective 3D simulation mapping production, which authorises the decision makers as well as investors to achieve permanent acceptance an independent navigation system for Geoscience applications.
Theory, Modeling and Simulation Annual Report 2000; FINAL
International Nuclear Information System (INIS)
Dixon, David A; Garrett, Bruce C; Straatsma, TP; Jones, Donald R; Studham, Scott; Harrison, Robert J; Nichols, Jeffrey A
2001-01-01
This annual report describes the 2000 research accomplishments for the Theory, Modeling, and Simulation (TM and S) directorate, one of the six research organizations in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) at Pacific Northwest National Laboratory (PNNL). EMSL is a U.S. Department of Energy (DOE) national scientific user facility and is the centerpiece of the DOE commitment to providing world-class experimental, theoretical, and computational capabilities for solving the nation's environmental problems
Experimental study and CFD simulation of rotational eccentric cylinder in a magnetorheological fluid
International Nuclear Information System (INIS)
Omidbeygi, F.; Hashemabadi, S.H.
2012-01-01
In this study, a magnetorheological (MR) fluid is prepared using carbonyl iron filings and low viscosity lubricating oil. The effects of magnetic field and weight percentage of particles on the viscosity of the MR fluid have been measured using a rotational viscometer. The yield stress under an applied magnetic field was also obtained experimentally. In the absence of an applied magnetic field, the MR fluid behaves as a Newtonian fluid. When the magnetic field is applied, the MR fluid behaves like Bingham plastics with a magnetic field dependent yield stress. Afterward, the results compared with those of CFD simulation of two eccentric cylinders in the MR fluid. Results show that the influences of MR effects, caused by the applied magnetic field, on the model characteristics are significant and not negligible. The viscosity is enhanced by increasing of the magnetic field, eccentricity ratio and weight percentage of suspensions. The MR effects and increasing of weight percentage and eccentricity ratio also provide an enhancement in the yield stresses and required total torque for rotation of inner cylinder. Also the simulation results indicate a good representation of the experiment by the model. - Highlights: ► Preparation of a magnetorheological fluid with carbonyl iron particles in lubricating oil. ► Rheological measurement for influence of solid content and magnetic field intensity. ► Simulation of eccentric rotating cylinder in prepared MR fluid with CFD techniques.
Standard Model theory calculations and experimental tests
International Nuclear Information System (INIS)
Cacciari, M.; Hamel de Monchenault, G.
2015-01-01
To present knowledge, all the physics at the Large Hadron Collider (LHC) can be described in the framework of the Standard Model (SM) of particle physics. Indeed the newly discovered Higgs boson with a mass close to 125 GeV seems to confirm the predictions of the SM. Thus, besides looking for direct manifestations of the physics beyond the SM, one of the primary missions of the LHC is to perform ever more stringent tests of the SM. This requires not only improved theoretical developments to produce testable predictions and provide experiments with reliable event generators, but also sophisticated analyses techniques to overcome the formidable experimental environment of the LHC and perform precision measurements. In the first section, we describe the state of the art of the theoretical tools and event generators that are used to provide predictions for the production cross sections of the processes of interest. In section 2, inclusive cross section measurements with jets, leptons and vector bosons are presented. Examples of differential cross sections, charge asymmetries and the study of lepton pairs are proposed in section 3. Finally, in section 4, we report studies on the multiple production of gauge bosons and constraints on anomalous gauge couplings
Quantitative interface models for simulating microstructure evolution
International Nuclear Information System (INIS)
Zhu, J.Z.; Wang, T.; Zhou, S.H.; Liu, Z.K.; Chen, L.Q.
2004-01-01
To quantitatively simulate microstructural evolution in real systems, we investigated three different interface models: a sharp-interface model implemented by the software DICTRA and two diffuse-interface models which use either physical order parameters or artificial order parameters. A particular example is considered, the diffusion-controlled growth of a γ ' precipitate in a supersaturated γ matrix in Ni-Al binary alloys. All three models use the thermodynamic and kinetic parameters from the same databases. The temporal evolution profiles of composition from different models are shown to agree with each other. The focus is on examining the advantages and disadvantages of each model as applied to microstructure evolution in alloys
A queuing model for road traffic simulation
International Nuclear Information System (INIS)
Guerrouahane, N.; Aissani, D.; Bouallouche-Medjkoune, L.; Farhi, N.
2015-01-01
We present in this article a stochastic queuing model for the raod traffic. The model is based on the M/G/c/c state dependent queuing model, and is inspired from the deterministic Godunov scheme for the road traffic simulation. We first propose a variant of M/G/c/c state dependent model that works with density-flow fundamental diagrams rather than density-speed relationships. We then extend this model in order to consider upstream traffic demand as well as downstream traffic supply. Finally, we show how to model a whole raod by concatenating raod sections as in the deterministic Godunov scheme
Clock error models for simulation and estimation
International Nuclear Information System (INIS)
Meditch, J.S.
1981-10-01
Mathematical models for the simulation and estimation of errors in precision oscillators used as time references in satellite navigation systems are developed. The results, based on all currently known oscillator error sources, are directly implementable on a digital computer. The simulation formulation is sufficiently flexible to allow for the inclusion or exclusion of individual error sources as desired. The estimation algorithms, following from Kalman filter theory, provide directly for the error analysis of clock errors in both filtering and prediction
Modeling and simulation goals and accomplishments
International Nuclear Information System (INIS)
Turinsky, P.
2013-01-01
The CASL (Consortium for Advanced Simulation of Light Water Reactors) mission is to develop and apply the Virtual Reactor simulator (VERA) to optimise nuclear power in terms of capital and operating costs, of nuclear waste production and of nuclear safety. An efficient and reliable virtual reactor simulator relies on 3-dimensional calculations, accurate physics models and code coupling. Advances in computer hardware, along with comparable advances in numerical solvers make the VERA project achievable. This series of slides details the VERA project and presents the specificities and performance of the codes involved in the project and ends by listing the computing needs
Simple model of surface roughness for binary collision sputtering simulations
Energy Technology Data Exchange (ETDEWEB)
Lindsey, Sloan J. [Institute of Solid-State Electronics, TU Wien, Floragasse 7, A-1040 Wien (Austria); Hobler, Gerhard, E-mail: gerhard.hobler@tuwien.ac.at [Institute of Solid-State Electronics, TU Wien, Floragasse 7, A-1040 Wien (Austria); Maciążek, Dawid; Postawa, Zbigniew [Institute of Physics, Jagiellonian University, ul. Lojasiewicza 11, 30348 Kraków (Poland)
2017-02-15
Highlights: • A simple model of surface roughness is proposed. • Its key feature is a linearly varying target density at the surface. • The model can be used in 1D/2D/3D Monte Carlo binary collision simulations. • The model fits well experimental glancing incidence sputtering yield data. - Abstract: It has been shown that surface roughness can strongly influence the sputtering yield – especially at glancing incidence angles where the inclusion of surface roughness leads to an increase in sputtering yields. In this work, we propose a simple one-parameter model (the “density gradient model”) which imitates surface roughness effects. In the model, the target’s atomic density is assumed to vary linearly between the actual material density and zero. The layer width is the sole model parameter. The model has been implemented in the binary collision simulator IMSIL and has been evaluated against various geometric surface models for 5 keV Ga ions impinging an amorphous Si target. To aid the construction of a realistic rough surface topography, we have performed MD simulations of sequential 5 keV Ga impacts on an initially crystalline Si target. We show that our new model effectively reproduces the sputtering yield, with only minor variations in the energy and angular distributions of sputtered particles. The success of the density gradient model is attributed to a reduction of the reflection coefficient – leading to increased sputtering yields, similar in effect to surface roughness.
Simple model of surface roughness for binary collision sputtering simulations
International Nuclear Information System (INIS)
Lindsey, Sloan J.; Hobler, Gerhard; Maciążek, Dawid; Postawa, Zbigniew
2017-01-01
Highlights: • A simple model of surface roughness is proposed. • Its key feature is a linearly varying target density at the surface. • The model can be used in 1D/2D/3D Monte Carlo binary collision simulations. • The model fits well experimental glancing incidence sputtering yield data. - Abstract: It has been shown that surface roughness can strongly influence the sputtering yield – especially at glancing incidence angles where the inclusion of surface roughness leads to an increase in sputtering yields. In this work, we propose a simple one-parameter model (the “density gradient model”) which imitates surface roughness effects. In the model, the target’s atomic density is assumed to vary linearly between the actual material density and zero. The layer width is the sole model parameter. The model has been implemented in the binary collision simulator IMSIL and has been evaluated against various geometric surface models for 5 keV Ga ions impinging an amorphous Si target. To aid the construction of a realistic rough surface topography, we have performed MD simulations of sequential 5 keV Ga impacts on an initially crystalline Si target. We show that our new model effectively reproduces the sputtering yield, with only minor variations in the energy and angular distributions of sputtered particles. The success of the density gradient model is attributed to a reduction of the reflection coefficient – leading to increased sputtering yields, similar in effect to surface roughness.
Simulation and experimental study of thermal performance of a ...
Indian Academy of Sciences (India)
of a building roof with a phase change material (PCM) .... ware model of concrete roof without cylindrical holes and PRO-E software model concrete roof .... John Kosnya, Kaushik Biswas, William Miller and Scott Kriner 2012 Field thermal ...
Energy performance of a ventilated façade by simulation with experimental validation
International Nuclear Information System (INIS)
Aparicio-Fernández, Carolina; Vivancos, José-Luis; Ferrer-Gisbert, Pablo; Royo-Pastor, Rafael
2014-01-01
A model for a building with ventilated façade was created using the software tool TRNSYS, version 17, and airflow parameters were simulated using TRNFlow. The results obtained with the model are compared and validated with experimental data. The temperature distribution along the air cavity was analysed and a chimney effect was observed, which produced the highest temperature gradient on the first floor. The heat flux of the external wall was analysed, and greater temperatures were observed on the external layer and inside the cavity. The model allows to calculate the energy demand of the building façade proposing and evaluating passive strategies. The corresponding office building for computer laboratories located in Valencia (Spain), was monitored for a year. The thermal behaviour of the floating external sheet was analysed using an electronic panel designed for the reading and storage of data. A feasibility study of the recovery of hot air inside the façade into the building was performed. The results obtained showed a lower heating demand when hot air is introduced inside the building, increasing the efficiency of heat recovery equipment. - Highlights: •An existing office building was monitored for a year. •A model of a ventilated façade by TRNSYS simulation tool was validated. •Air flow parameters inside the ventilated façade were identified. •Recovery of the hot air inside the façade for input into the building was studied
Otto-Bliesner, B.; Braconnot, P.; Harrison, S.P.; Renssen, H.
2017-01-01
Two interglacial epochs are included in the suite of Paleoclimate Modeling Intercomparison Project (PMIP4) simulations in the Coupled Model Intercomparison Project (CMIP6). The experimental protocols for Tier 1 simulations of the mid-Holocene (midHolocene, 6000 years before present) and the Last
Otto-bliesner, Bette L.; Braconnot, Pascale; Harrison, Sandy P.; Lunt, Daniel J.; Abe-Ouchi, Ayako; Albani, Samuel; Bartlein, Patrick J.; Capron, Emilie; Carlson, Anders E.; Dutton, Andrea; Fischer, Hubertus; Goelzer, Heiko|info:eu-repo/dai/nl/412549123; Govin, Aline; Haywood, Alan; Joos, Fortunat; Legrande, Allegra N.; Lipscomb, William H.; Lohmann, Gerrit; Mahowald, Natalie; Nehrbass-Ahles, Christoph; Pausata, Francesco S. R.; Peterschmitt, Jean-yves; Phipps, Steven J.; Renssen, Hans; Zhang, Qiong
2017-01-01
Two interglacial epochs are included in the suite of Paleoclimate Modeling Intercomparison Project (PMIP4) simulations in the Coupled Model Intercomparison Project (CMIP6). The experimental protocols for simulations of the mid-Holocene (midHolocene, 6000 years before present) and the Last
Experimental simulation of microinteractions in large scale explosions
Energy Technology Data Exchange (ETDEWEB)
Chen, X.; Luo, R.; Yuen, W.W.; Theofanous, T.G. [California Univ., Santa Barbara, CA (United States). Center for Risk Studies and Safety
1998-01-01
This paper presents data and analysis of recent experiments conducted in the SIGMA-2000 facility to simulate microinteractions in large scale explosions. Specifically, the fragmentation behavior of a high temperature molten steel drop under high pressure (beyond critical) conditions are investigated. The current data demonstrate, for the first time, the effect of high pressure in suppressing the thermal effect of fragmentation under supercritical conditions. The results support the microinteractions idea, and the ESPROSE.m prediction of fragmentation rate. (author)
Experimental validation of solid rocket motor damping models
Riso, Cristina; Fransen, Sebastiaan; Mastroddi, Franco; Coppotelli, Giuliano; Trequattrini, Francesco; De Vivo, Alessio
2017-12-01
In design and certification of spacecraft, payload/launcher coupled load analyses are performed to simulate the satellite dynamic environment. To obtain accurate predictions, the system damping properties must be properly taken into account in the finite element model used for coupled load analysis. This is typically done using a structural damping characterization in the frequency domain, which is not applicable in the time domain. Therefore, the structural damping matrix of the system must be converted into an equivalent viscous damping matrix when a transient coupled load analysis is performed. This paper focuses on the validation of equivalent viscous damping methods for dynamically condensed finite element models via correlation with experimental data for a realistic structure representative of a slender launch vehicle with solid rocket motors. A second scope of the paper is to investigate how to conveniently choose a single combination of Young's modulus and structural damping coefficient—complex Young's modulus—to approximate the viscoelastic behavior of a solid propellant material in the frequency band of interest for coupled load analysis. A scaled-down test article inspired to the Z9-ignition Vega launcher configuration is designed, manufactured, and experimentally tested to obtain data for validation of the equivalent viscous damping methods. The Z9-like component of the test article is filled with a viscoelastic material representative of the Z9 solid propellant that is also preliminarily tested to investigate the dependency of the complex Young's modulus on the excitation frequency and provide data for the test article finite element model. Experimental results from seismic and shock tests performed on the test configuration are correlated with numerical results from frequency and time domain analyses carried out on its dynamically condensed finite element model to assess the applicability of different equivalent viscous damping methods to describe
Experimental validation of solid rocket motor damping models
Riso, Cristina; Fransen, Sebastiaan; Mastroddi, Franco; Coppotelli, Giuliano; Trequattrini, Francesco; De Vivo, Alessio
2018-06-01
In design and certification of spacecraft, payload/launcher coupled load analyses are performed to simulate the satellite dynamic environment. To obtain accurate predictions, the system damping properties must be properly taken into account in the finite element model used for coupled load analysis. This is typically done using a structural damping characterization in the frequency domain, which is not applicable in the time domain. Therefore, the structural damping matrix of the system must be converted into an equivalent viscous damping matrix when a transient coupled load analysis is performed. This paper focuses on the validation of equivalent viscous damping methods for dynamically condensed finite element models via correlation with experimental data for a realistic structure representative of a slender launch vehicle with solid rocket motors. A second scope of the paper is to investigate how to conveniently choose a single combination of Young's modulus and structural damping coefficient—complex Young's modulus—to approximate the viscoelastic behavior of a solid propellant material in the frequency band of interest for coupled load analysis. A scaled-down test article inspired to the Z9-ignition Vega launcher configuration is designed, manufactured, and experimentally tested to obtain data for validation of the equivalent viscous damping methods. The Z9-like component of the test article is filled with a viscoelastic material representative of the Z9 solid propellant that is also preliminarily tested to investigate the dependency of the complex Young's modulus on the excitation frequency and provide data for the test article finite element model. Experimental results from seismic and shock tests performed on the test configuration are correlated with numerical results from frequency and time domain analyses carried out on its dynamically condensed finite element model to assess the applicability of different equivalent viscous damping methods to describe
Simulation Modeling of Software Development Processes
Calavaro, G. F.; Basili, V. R.; Iazeolla, G.
1996-01-01
A simulation modeling approach is proposed for the prediction of software process productivity indices, such as cost and time-to-market, and the sensitivity analysis of such indices to changes in the organization parameters and user requirements. The approach uses a timed Petri Net and Object Oriented top-down model specification. Results demonstrate the model representativeness, and its usefulness in verifying process conformance to expectations, and in performing continuous process improvement and optimization.
Experimental simulation and limitations of quantum walks with trapped ions
International Nuclear Information System (INIS)
Matjeschk, R; Schneider, Ch; Enderlein, M; Huber, T; Schmitz, H; Glueckert, J; Schaetz, T
2012-01-01
We examine the prospects of discrete quantum walks (QWs) with trapped ions. In particular, we analyze in detail the limitations of the protocol of Travaglione and Milburn (2002 Phys. Rev. A 65 032310) that has been implemented by several experimental groups in recent years. Based on the first realization in our group (Schmitz et al 2009 Phys. Rev. Lett. 103 090504), we investigate the consequences of leaving the scope of the approximations originally made, such as the Lamb-Dicke approximation. We explain the consequential deviations from the idealized QW for different experimental realizations and an increasing number of steps by taking into account higher-order terms of the quantum evolution. It turns out that these already become significant after a few steps, which is confirmed by experimental results and is currently limiting the scalability of this approach. Finally, we propose a new scheme using short laser pulses, derived from a protocol from the field of quantum computation. We show that this scheme is not subject to the above-mentioned restrictions and analytically and numerically evaluate its limitations, based on a realistic implementation with our specific setup. Implementing the protocol with state-of-the-art techniques should allow for substantially increasing the number of steps to 100 and beyond and should be extendable to higher-dimensional QWs. (paper)