Simulator nested

The simulations nested in the coarse grid METRAS results agree in a similar way with the reference simulation in the second half of the simulation time (after about 21 h i.e. 18 CET of 29 August 2003). At this time the performance of simulation 5 is somewhat closer to the other nested simulations than before. This might be a hint that the nesting becomes less relevant and the situation is more locally driven. In the first 21 h of the simulation the two simulations with constant update intervals (3 h, 6 h) are closest to the reference case, while the adaptive update simulations (3, 4) show a high variability in performance. This is a hint that the acceleration is probably not a reliable measure to determine update intervals. The best performance is received in the present case study for a nesting every 3 h. 

The computer effort required for convergence depends on the number and complexity of the recycles ia the dowsheet, the nonlinearities ia the physical properties, and the nonlinearities ia the calculation of phase or chemical equiHbria. In sequential-modular simulators these calculations are converged one at a time, sequentially, and ia a nested manner. In equation-oriented simulators they are converged as a group and, ia the case of complex dow sheets involving nonideal mixtures, there could be significant reduction ia computer effort. 

Hierarchical Structure. In order to be better able to simulate the hierarchical nature of many real-world complex systems, in which agent behavior can itself be best described as being the result of the collective behavior of some swarm of constituent agents. Swarm is designed so that agents themselves can be swarms of other agents. Moreover, Swarm is designed around a time hierarchy, Thus, Swarm is both a nested hierarchy of swarms and a nested hierarchy of schedules. 

This is based on the example of Matko, Korba and Zupancic (1), who describe methods of simulating process transform functions, based on partitioned and nested forms of solution. Here the process transfer function is given by... 

Some recent applications have benefited from advances in computing and computational techniques. Steady-state simulation is being used off-line for process analysis, design, and retrofit process simulators can model flow sheets with up to about a million equations by employing nested procedures. Other applications have resulted in great economic benefits these include on-line real-time optimization models for data reconciliation and parameter estimation followed by optimal adjustment of operating conditions. Models of up to 500,000 variables have been used on a refinery-wide basis. 

D Monte Carlo A kind of nested Monte Carlo simulation in which distributions representing both incertitude and variability are combined together. Typically, the outer loop selects random values for the parameters specifying the distributions used in an inner loop to represent variability. 

Notice that two values are displayed in the Simulation Status window. The bottom line changes quickly and is the main sweep variable, Vs. The line second to the bottom is the nested sweep variable, BV. Notice that for each value of BV, Vs is swept from -15 to +15. Logically, the primary sweep loop executes inside the secondary sweep loop. That is, BV is set to 1 and Vs is swept from -15 to +15. Then BV is set to 2, and Vs is swept from —15 to +15. Then BV is set to 3, and Vs is swept from -15 to +15, and so on. When the analysis is finished, Probe will run. Add the trace V(VL) (press the INSERT key) ... 

The simulation status window indicates the progress of each loop. Notice that for each value of the nested variable, the main variable is swept from 0 to 15 volts. When the simulation is finished, the Probe window will display a blank window. I W N switch Probe to occupy the entire window. Press the INSERT key and add the trace IC (Ql) ... 

Figure 4.15 Hebeloma danicum (arrowhead) and H. mdicosoides (the rest) fruiting on buried uric acid, which simulates their growth on abandoned nests of wasps underground (see Section 3.4). Twenty-five g of uric acid was buried together with humus (arrow) at the bottom (20 x 20 cm) of a 20 cm deep hole on December 8, 1984, in a Pinus-Quercus forest, Shiga, Japan photograph taken on October 17, 1985.

In order to investigate possible effects of global climate change on the near-surface concentrations of photochemical compounds in southern Germany, nested regional simulations with MCCM were carried out (Forkel and Knoche 2006). The simulations with horizontal resolutions of 60 (for whole Europe) and 20 km (for central... 

Interface Module and Model Nesting Effects on Air Quality Simulation... 

The regional air quality (AQ) forecasting system of FMI has been set up in 2005 and opened for public access via internet in 2006 (http //silam.fmi.fi). A primary goal of the system is to evaluate and forecast the air pollution over the Finnish territory. Since Finland is a receptor of practically all main pollutants, the area of the simulations is necessarily covered the whole of Europe with a compromising resolution of 30 km. A nested domain was introduced in 2007 and it covers northern Europe with a resolution of 10 km. 

Technically, the transfer of the information from the ACTM to meteorological model is straightforward. For the operational forecasts, the next cycle meteorological calculations can use the previous cycle chemical composition results. For the case of nested simulations, both re-analyses and forecasts, the next-step nested meteorological computations can utilise the previous-step composition data. 

Changes in the atmospheric fields happen on different time scales and with different speed. Therefore, we adapt the time intervals for writing the model results (that are the forcing data for nested simulations) to the time scales, in which the atmospheric fields change, instead of using short but constant time intervals. If significant changes happen on short time scales, the results should be written more often than for more or less steady conditions. 

Fig. 19.1 The model areas used for the coarse grid run yielding the forcing data (a) and for the nested simulations for the case low pressure system over Europe (b). The positioning of the nested area is shown by the frame in (a)...

METRAS is able to yield simulation results on different scales and details. Nesting is a helpful tool to improve the model performance if the forcing data represent the meteorological situation in a realistic way. The current studies on the impact of update interval lengths on model performance lead to the following conclusions ... 

Experimental heat of adsorption obtained by chromatography at zero coverage is compared with simulated heat of adsorption for 3 models in Table 2. Here simulation for the acid site model was closer to the experimental value than the pure siliceous model and the silanol nest model. 

The adsorption equilibria were measured using a gravimetric method and were expressed as isotherms. A chromatographic method was used to get the initial slope of the isotherms. In the simulation, GCMC method was used to calculate amounts adsorbed for various conditions. When the experiment result and simulation result of chloroform are compared, the simulation for the acid site model was most agreement with chromatographic data and baratron data. The simulation result of tetrachloroethylene with three models corresponded mostly for the non-polar molecule, and above all the acid site model was the closest to the experiment result. Therefore, to get better coincidence between experimental data and simulation, it was found to be necessary to account for aluminum rather than silanol nest. 

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