10,004 research outputs found
Geothermal systems simulation: A case study
Geothermal reservoir simulation is a key step for developing sustainable and efficient strategies for the exploitation of geothermal resources. It is applied in the assessment of several areas of reservoir engineering, such as reservoir performance and re-injection programs, pressure decline in depletion, phase transition conditions, and natural evolution of hydrothermal convection systems. Fluid flow and heat transfer in rock masses, fluid-rock chemical interaction and rock mass deformation are some of the processes addressed in reservoir modelling. The case study of the Las Tres Virgenes (LTV) geothermal field (10 MWe), Baja California Sur, Mexico is presented. Three dimensional (3D) natural state simulations were carried out from emplacement and cooling of two spherical magma chambers using a conductive approach. A conceptual model of the volcanic system was developed on a lithostratigraphic and geochronological basis. Magma chamber volumes were established from eruptive volumes estimations. The thermophysical properties of the medium were assumed to correspond to the dominant rock in each lithological unit as an initial value, and further calibration was made considering histograms of experimentally obtained thermophysical properties of rocks. As the boundaries of the model lie far from the thermal anomaly, we assumed specified temperature boundaries. A Finite Volume (FV) numerical scheme was implemented in a Fortran 90 code to solve the heat equation. Static formation temperatures from well logs were used for validation of the numerical results. Good agreement was observed in those geothermal wells dominated by conductive heat transfer. For other wells, however, it is clear that conduction alone cannot explain observed behaviour, three-dimensional convective models are being implemented for future multiphysics simulations
Cyber-Virtual Systems: Simulation, Validation & Visualization
We describe our ongoing work and view on simulation, validation and
visualization of cyber-physical systems in industrial automation during
development, operation and maintenance. System models may represent an existing
physical part - for example an existing robot installation - and a software
simulated part - for example a possible future extension. We call such systems
cyber-virtual systems.
In this paper, we present the existing VITELab infrastructure for
visualization tasks in industrial automation. The new methodology for
simulation and validation motivated in this paper integrates this
infrastructure. We are targeting scenarios, where industrial sites which may be
in remote locations are modeled and visualized from different sites anywhere in
the world.
Complementing the visualization work, here, we are also concentrating on
software modeling challenges related to cyber-virtual systems and simulation,
testing, validation and verification techniques for them. Software models of
industrial sites require behavioural models of the components of the industrial
sites such as models for tools, robots, workpieces and other machinery as well
as communication and sensor facilities. Furthermore, collaboration between
sites is an important goal of our work.Comment: Preprint, 9th International Conference on Evaluation of Novel
Approaches to Software Engineering (ENASE 2014
Measurement criteria in man machine systems simulation
Simulation, models, and games as analogies measurement criteria in man-machine system simulatio
Application of control theory to dynamic systems simulation
The application of control theory is applied to dynamic systems simulation. Theory and methodology applicable to controlled ecological life support systems are considered. Spatial effects on system stability, design of control systems with uncertain parameters, and an interactive computing language (PARASOL-II) designed for dynamic system simulation, report quality graphics, data acquisition, and simple real time control are discussed
Nonlinear Control Systems Simulation Using Spreadsheets
In this paper, a method for simulating nonlinear control systems using spreadsheets is presented. Various nonlinear blocks are simulated using graphics and cell formulas, and are generated by clicking on specially developed toolbar buttons. These blocks can be connected to one another using a simple and intuitive procedure again based on graphics and toolbar buttons. A complete nonlinear system can thus be created by generating and connecting its constituting basic blocks, using the simple graphics interface provided. The corresponding data may then be entered in the familiar manner as illustrated, and finally the system can be simulated literally at the click of a button. Such a system can be analyzed by calculating its time response to any input signal or by using other methods such as phase-plane trajectories. The simulation is characterized by its availability, flexibility, and simplicity. The paper provides several examples to illustrate the simulation capabilities available. The first example considers a servo with a dead-zone and a saturation amplifier, the second illustrates the steps required to obtain a phase-plane trajectory, and the third example considers a nonlinear system having a PI controller and nonlinearity consisting of soft saturation. The final example illustrates a relay-controlled servo system
Weak Lensing by Intergalactic Mini-Structures in Quadruple Lens Systems: Simulation and Detection
We investigate the weak lensing effects of line-of-sight structures on
quadruple images in quasar-galaxy strong lens systems based on N-body and
ray-tracing simulations that can resolve halos with a mass of 10^5 solar mass.
The intervening halos and voids disturb the magnification ratios of lensed
images as well as their relative positions due to lensing. The magnification
ratios typically change by O(10%) when the shifts of relative angular positions
of lensed images are constrained to <0.004 arcsec. The constrained amplitudes
of projected density perturbations due to line-of-sight structures are O(10^8)
solar mass per arcsec^2. These results are consistent with our new analytical
estimate based on the two-point correlation of density fluctuations. The
observed mid-infrared (MIR) flux ratios for 6 quasar-galaxy lens systems with
quadruple images agree well with the numerically estimated values without
taking into account of subhalos residing in the lensing galaxies. We find that
the constrained mean amplitudes of projected density perturbations in the
line-of-sight are negative, which suggests that the fluxes of lensed images are
perturbed mainly by minivoids and minihalos in underdense regions. We derive a
new fitting formula for estimating the probability distribution function of
magnification perturbation. We also find that the mean amplitude of
magnification perturbation roughly equals the standard deviation regardless of
the model parameters.Comment: 22 pages, 15 figures, accepted for publication in MNRA
Identification of linear systems. Simulation studies Final report, Feb. 1967 - Apr. 1968
Analytical development and computerized simulation of parameter estimation technique for identifying linear and nonlinear system
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