Using Graphs of Queues and Genetic Algorithms to Fast Approximate Crowd Simulations

Influence of two- and three-dimensional simulations on bubble behavior in gas–solid fluidized beds with and without immersed horizontal tubes

In spite of the importance of a detailed description of the filamentary current constriction of the IGBT during the turn-off operation that could lead to the device’s failure, there are to date no quantitative 3D simulation results of the filament growth and dynamic that can be compared with experimental results. In this paper we present 3D numerical simulations on the failure mode in the Unclamped Inductance Switching (UIS) test operation, extended to the full device area, which will be usefully compared with detailed experimental results on a large number of trench IGBT test samples. For the first time extended 3D dynamic electrothermal simulations of the whole die are made, to take into account both the electric and thermal effects of the filamentary conduction in avalanche mode. The onset of a filament growth condition for a current level just above the turnover voltage evaluated by the 3D simulations, and the area of the filament, obtained for the first time, are well in agreement with the quantitative data extracted by the experimental evaluations. Moreover, the thermal heating due to the filament formation is found to be quite independent from the current level, because it depends on the current density in the filament, rather than on the injected current. The delay time between the filament formation and the final failure time seen in the experimental results is verified to be due to the movement of the filament all around the chip surface in search of a cooler spot. The movement of the filament along the whole die area is verified for the first time by full area 3D electrothermal dynamic simulations, with times in agreement with the experimental delay between filament formation and final failure seen in all the failure reports.

There have been remarkable advances in semiconductor industry but the miniaturization of magnetic devices is progressed very slowly. So many studies are carried out overcoming the gap. To develop small size devices, proper design and property simulation of the devices are requested to spare the efforts before fabrication processes. However, there is a few of simulation studies have been reported. In this work, we fabricated thin film toroidal inductors using permalloy as a core material and measured the properties to estimate 2D and 3D simulation in the magnetic devices. The 3D simulation shows more agreeable results than the 2D simulation. On the other hand, when we changed core materials, the inductor using Fe-Hf-C-N nanocrystalline alloys as core material shows the better properties than using permalloy and Fe-Zr-C-N alloys.

We used ultrasonic shear waves for nondestructive defect detection in a billet using transmitted waves. We utilized the deviation the time-of-flight (TOF) obtained by cross-correlation of transmitted waves of a defect-free reference plane and that of a measurement plane containing a defect. We compared the performance of longitudinal waves and shear waves at different wavelengths in detecting the diameter of a circular defect in two-dimensional (2D) simulation and the TOF for a cylindrical defect while changing the vibration direction of shear waves in three-dimensional (3D) simulation. Shear waves detected defects better than longitudinal waves in the 2D simulation, especially at wavelengths of 1.4–2.4 mm. In the 3D simulation, the maximum TOF was larger when the vibration direction was perpendicular to the defect’s major axis than when it was parallel in the measurement using shear waves. This suggests a defect’s shape can be estimated by measurement using shear waves.

Two- and three-dimensional Direct Numerical Simulation of particle-laden gravity currents

Modified social force model considering emotional contagion for crowd evacuation simulation

In this study, E-Scaffolding Enhance Learning (ESEL) using Web-based simulation has been designed and implemented. The scaffolding approach in this research is a conceptual scaffolding of the moment of inertia. Web-based simulation consists of 2D and 3D simulation. The 3D simulation was developed using unity software and 2D simulation was developed using scratch and articulate storyline software. All simulation was published as an Html file, and finally inserted into the website. The validation of the product was carried out by experts such as a physics lecturer and a physics teacher. The implementation phase was carried out through collaborative distance learning between one Senior High School in Bandung and one school in West Nusa Tenggara. The validation results show that ESEL using Web-based simulation on moment of inertia is deserved with an average score of 92% in the very good category. Nevertheless, there are several improvements still need to be made in terms of the appearance of the Web-based 3D simulation especially when it is accessed by phone cell. The appearance of the Web-based 3D simulation is still not responsive for smartphones. But based on the questionnaire result of students, ESEL using Web-based simulation on moment of inertia has a value 71% which means that ESEL has a good category of validation and is interesting for the students. ESEL using Web-based simulation also improves students’ activities in the distance learning of physics classroom.

Strategic planning for airport design and operations is a challenging task, since it should consider a variety of alternative futures, their consequences for airport performance and possible strategies for ensuring that the airport meets its business objectives. Existing models and tools for quantifying airport performance require significant detailed data, substantial airport modelling effort and do not readily produce the information relevant to decision makers. Therefore, a fast and simple simulation model is needed that provides insight into the key performance indicators of an airport for different strategies across different futures. In this paper, a simple simulation model is developed, and different scenarios with increasing traffic and changing traffic distribution are simulated with a general simulation platform called ProModel, which can provide output data for airport capacity evaluation and a bottleneck checking. Case study shows that the model can be easily executed and proved to be feasible to quickly generate interest results for decision makers.

Highlights Bin filler design and bin dimensions determine apple distribution Performance of new apple distribution systems was estimated with 3D simulations Simulated lemniscate scattering path demonstrated improved apple distribution in rectangular bins 3D simulation provides an efficient, informed design decision tool before going into production Abstract. Mechanical harvest platform systems equipped with conveyors were meant to replace the traditional apple-picking ladder and bucket; however, their feasibility has not yet been exhausted. The conveyor belts transport the apples to the bin filler, whose role is to distribute the fruit into the bins. Commercial mechanical harvest platforms are designed to perform well with square bins; however, Israeli apple industry bins are rectangular. This results in a non-uniform apple distribution, which requires human intervention and contributes to apple bruising and economic loss. In the present study, a 3D simulation was used to quantitatively evaluate the performance of three novel bin filler designs (back-and-forth, double disk, and lemniscate) and compare them to commercial bin fillers. The bin filler models were tested for the uniformity of the apples distributed into square and rectangular bins. The angle of repose and the standard deviation of the height of the top layer of apples were calculated. The commercial bin filler model performed better when filling square bins (angle = 12°, SD height = 31 mm) than rectangular bins (angle = 18°, SD height = 71 mm). The lemniscate model (angle = 10°, SD height = 41 mm) outperformed the two others as well as the commercial bin filler model (collapsed: angle = 18°, height = 67 mm). A machine design for the lemniscate model is proposed. The quantitative methods described in this study point to the potential benefit of 3D simulation as an inexpensive means to explore the feasibility of new harvest devices.

Large progress has been realized in modeling conduction heat transfer problems over the past decade by the introduction of high performance compact thermal models (CTMs) mainly developed for thermal design of complicated electronic systems. The objective of this paper is to generalize these advances to convective heat transfer. A new convective CTM is proposed, which offers many advantages over the traditional approach using the heat transfer coefficient (HTC). The latter is simply a zeroth order CTM. The HTC is quite handy and simple, but with unpredictable errors. It can be suitable for hand calculations of simple systems giving rather crude estimates. For a higher precision, users have no other option than time consuming 3D simulations. For large systems, in terms of number of components, 3D simulations can be rapidly impractical. The CTM bridges the gap between both approaches going gradually from “HTC” levels (low precision and calculations time) at the zeroth order, to 3D simulation precision and computing time levels at large orders. Fortunately, like for conduction, a CTM of order of few tens quickly approaches 3D simulation precision levels, while keeping computation time significantly lower than 3D simulation. Moreover, the CTM approach solves conjugate heat transfer problems in a quite elegant way. A “black box” model, developed for fluid domain alone, can be easily combined with classical CTM conduction models to generate good precision predictions for any combination of fluid/solid domains.

Assessment of energy production from photovoltaic modules integrated in typical shading devices

3D validation, 2D feasibility, corrected and developed correlations for pure solid-gallium phase change modeling by enthalpy-porosity methodology

Eddy currents in permanent magnets of synchronous machines may cause their demagnetization due to overheating. Thus eddy current analysis has been discussed widely. 3D transient analyses of eddy current losses yield most accurate results but are also performed at very high computational cost. A previously introduced more efficient 2D approach for accurate eddy current calculation is adapted in this publication for the use with interior permanent magnet machines. Instead of only considering axial eddy currents inside the magnets, radial eddy current displacement is considered by analyzing the magnets in multiple sectional planes. The computed results comply with the theoretical expectations and the results from a 3D simulation. This confirms the method's applicability as a quick and accurate alternative to costly 3D eddy current simulations.

Context.Convective motions at the stellar surface generate a stochastic colored noise source in the radial velocity (RV) data. This noise impedes the detection of small exoplanets. Moreover, the unknown statistics (amplitude, distribution) related to this noise make it difficult to estimate the false alarm probability (FAP) for exoplanet detection tests.Aims.In this paper, we investigate the possibility of using 3D magneto-hydrodynamical (MHD) simulations of stellar convection to design detection methods that can provide both a reliable estimate of the FAP and a high detection power.Methods.We tested the realism of 3D simulations in producing solar RV by comparing them with the observed disk integrated velocities taken by the GOLF instrument on board the SOHO spacecraft. We presented a new detection method based on periodograms standardized by these simulated time series, applying several detection tests to these standarized periodograms.Results.The power spectral density of the 3D synthetic convective noise is consistent with solar RV observations for short periods. For regularly sampled observations, the analytic expressions of FAP derived for several statistical tests applied to the periodogram standardized by 3D simulation noise are accurate. The adaptive tests considered in this work (Higher-Criticism, Berk-Jones), which are new in the exoplanet field, may offer better detection performance than classical tests (based on the highest periodogram value) in the case of multi-planetary systems and planets with eccentric orbits.Conclusions.3D MHD simulations are now mature enough to produce reliable synthetic time series of the convective noise affecting RV data. These series can be used to access to the statistics of this noise and derive accurate FAP of tests that are a critical element in the detection of exoplanets down to the cm s−1level.

The purpose of this paper is to shed light on how and when 3D simulations are preferable over 2D simulations in order to predict the replicated height of nanocavities via plastic injection moulding. Simulations are necessary since not all the cavity is copied depending on geometrical and injection conditions. A 3D simulation is preferable over a 2D simulation in two cases: (i) when the heat transfer through the walls parallel to the simulated domain is not negligible and (ii) when the polymer final shape is relevant. This work explains when 2D simulations like the more commonly found in the literature are not enough to obtain reliable results and how to obtain such results by means of a 3D simulation.