3D Simulation of Nanostructures Replication via Injection Molding

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.

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.

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.

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

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.

Plastic pumps are used to efficiently move liquids within aquaculture systems and seafood processing facilities. Commonly, the centrifugal pump casing is fabricated by plastic injection molding technology. In the plastic injection molding process, the control parameters are essential to the success of plastic molding product fabrication. This study aims to optimize process parameters for the quality of centrifugal pump casing during plastic injection molding using a combination of response surface methodology (RSM) and the NSGA-II method. Firstly, the L27 orthogonal array design of the experiment method is used, which has four input variables, including plastic temperature, mold temperature, cooling time, and injection time (filling time and packing time). The output responses of the injection molding process to be evaluated are the warpage and shrinkage deformation of the molded product. After obtaining data, the RSM model is applied to describe the relationship between the input and output variables. Finally, multi-objective optimization uses the NSGA-II method for the best product quality. The results show that the optimized parameters for injection molding of the centrifugal pump casing are a plastic temperature of 200°C, mold temperature of 65°C, cooling time of 25s, and injection time of 10s with warpage of 0.868 mm, and shrinkage of 10.104mm.

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.

A comparative study between two- and three-dimensional (2D and 3D) modeling is carried out on arc discharge phenomena inside a thermal plasma torch with hollow electrodes, in order to evaluate the effects of arc root configuration characterized by either 2D annular or 3D highly localized attachment on the electrode surface. For this purpose, a more precise 3D transient model has been developed by taking account of 3D arc current distribution and arc root rotation. The 3D simulation results apparently reveal that the 3D arc root attachment brings about the inherent 3D and turbulence nature of plasma fields inside the torch. It is also found that the constricted arc column near the vortex chamber plays an important role in heating and acceleration of injected arc gases by concentrating arc currents on the axis of the hollow electrodes. The inherent 3D nature of arc discharge is well preserved inside the cathode region, while these 3D features slowly diminish behind the vortex chamber where the turbulent flow begins to be developed in the anode region. Based on the present simulation results, it is noted that the mixing effects of the strong turbulent flow on the heat and mass transfer are mainly responsible for the gradual relaxation of the 3D structures of plasma fields into the 2D axisymmetric ones that eventually appear in the anode region near the torch exit. From a detailed comparison of the 3D results with the 2D ones, the arc root configuration seems to have a significant effect on the heat transfer to the electrode surfaces interacting with the turbulent plasma flow. That is, in the 2D simulation based on an axisymmetric stationary model, the turbulence phenomena are fairly underestimated and the amount of heat transferred to the cold anode wall is calculated to be smaller than that obtained in the 3D simulation. For the validation of the numerical simulations, calculated plasma temperatures and axial velocities are compared with experimentally measured ones, and the 3D simulation turns out to be more accurate than the 2D simulation as a result of a relatively precise description of the turbulent phenomena inside the torch using a more realistic model of arc root attachment. Finally, it is suggested that the 3D transient formulation is indeed required for describing the real arc discharge phenomena inside the torch, while the 2D stationary approach is sometimes useful for getting practical information about the time-averaged plasma characteristics outside the torch because of its simplicity and rapidness in computation.

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 use of Crowd Simulation for re-enacting different real life scenarios has been studied in the literature. In this field of research, the interplay between ambient assisted living solutions and the behavior of pedestrians in large installations is highly relevant. However, when designing these simulations, the necessary simplifications may result in different ranges of accuracy. The more realistic the simulation task is, the more complex and computational expensive it becomes. We present an approach towards a reasonable trade-off: given a complex and computational expensive crowd simulation, how to produce fast crowd simulations whose results approximate the results of the detailed and more realistic model. These faster simulations can be used to forecast the outcome of several scenarios, enabling the use of simulations in decision-making methods. This work contributes with a simplified faster simulation model that uses a graph of queues for modeling an environment where a set of agents will navigate. This model is configured using Genetic Algorithms (GA) applied to data obtained from complex 3D crowd simulations. This is illustrated with a proof-of-concept scenario where a 3D simulation of one floor of a faculty building, with its corresponding students, is re-enacted in the network of queues version. The success criteria are achieving a similar total number of people in particular floor areas along the simulation in both the simplified simulation and the original one. The experiments confirm that this approach approximates the number of people in each area with a sufficient degree of fidelity with respect to the results that are obtained by a more complex 3D simulator.

Experimental verification of three-dimensional simulations of LTO layer deposition on structures prepared by anisotropic wet etching of silicon