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[Abstract] Large eddy simulation with flltered-structure-function subgrid model and implicit large eddy simulation (ILES without explicit subgrid model) using high-order accuracy and high resolution compact scheme have been perfor...
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[Abstract] Large eddy simulation with flltered-structure-function subgrid model and implicit large eddy simulation (ILES without explicit subgrid model) using high-order accuracy and high resolution compact scheme have been performed on the tip vortex shedding from a rectangular half-wing with a NACA 0012 airfoil section and a rounded wing tip. The formation of the tip vortex and its initial development in the boundary layer and the near field wake are investigated and analyzed in detail. The physics, why the tip vortex, which is originally turbulent in the boundary layer, is re-laminarized and becomes stable and laminar rapidly after shedding in the near field, is revealed by this simulation. The computation also shows the widely used second order subgrid model is not consistent to six-order compact scheme and would degenerate the six-order LES results to second order. Therefore, high order schemes, gird refinement and six order subgrid models are critical to LES approaches.
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A consortium of 13 Historically Black Colleges and Universities (HBCUs) has been collaborating for more than four years resulting in the implementation of experiment centric pedagogy (ECP) in over forty courses that involve circui...
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A consortium of 13 Historically Black Colleges and Universities (HBCUs) has been collaborating for more than four years resulting in the implementation of experiment centric pedagogy (ECP) in over forty courses that involve circuits and electronics. ECP is enabled in this project through the use of mobile, inexpensive personal electronic instrumentation; usually Digilent's Analog Discovery (AD). ECP allows students with various learning styles to learn at their own pace and in their own environments by providing an alternative path to the acquisition of technical skills and knowledge both in the classroom and outside. Most of the courses addressed have been in the circuits and electronics sequence in electrical and computer engineering programs. Faculty involved in this effort has also used the same approach to support hands-on learning in introductory engineering courses, both focused on general engineering and specifically on introduction to ECE, in courses outside of ECE and in capstone design courses. This program was initiated and funding obtained because the group recognized that integrating hands-on learning is one of the key approaches that has been proven to be effective in improving retention by making the learning experience engaging and motivating for students. Results of internal and external evaluation has shown the introduction of AD board based ECP to be successful in a variety of instructional settings, instructional methodologies, and with diverse learning styles. This project has benefited from and inspired similar work by faculty at other universities who have been officially and unofficially affiliated with the 13 HBCUs. In this paper we will report on the immediate classroom impact of ECP on the engineering student as well as the long-term systemic experience at institutions both inside and outside the HBCU project.
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For more than fifty years US Navy submarines have used a body-of-revolution (BOR) hull design. Even the ballistic missile submarines have used a BOR hull design with the addition of a deck to cover the missile hatches. With the CN...
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For more than fifty years US Navy submarines have used a body-of-revolution (BOR) hull design. Even the ballistic missile submarines have used a BOR hull design with the addition of a deck to cover the missile hatches. With the CNO's recent emphases on improving the ocean interface, and developing modularity for the submarine's payload (OPNAV N875, 2000), the possibility of using a non-body-of-revolution (NBOR) has been suggested. With this type of hull a submarine could be developed that would allow dockside payload module changes including, but not limited to: ballistic missile modules, conventional missile modules, ASDS vehicle modules, SDV modules, and mine modules. The navy has very little experimental data on non-body-of-revolution hull forms and the little that is available has no systematic variation. The Maneuvering and Control Division of the David Taylor Model Basin, Naval Surface Warfare Center (NSWC) is developing improved techniques for quantifying and predicting the maneuvering characteristics for NBOR submersibles. Two distinct areas of work are described in this paper: 1-Parametric captive model experiments to determine the effects on stability and control due to geometric changes; and, 2-A study to determine the effects of L/D on the BOR series of models.
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Deep learning approaches achieve prominent success in 3D semantic segmentation. However, collecting densely annotated real-world 3D datasets is extremely time-consuming and expensive. Training models on synthetic data and generali...
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Deep learning approaches achieve prominent success in 3D semantic segmentation. However, collecting densely annotated real-world 3D datasets is extremely time-consuming and expensive. Training models on synthetic data and generalizing on real-world scenarios becomes an appealing alternative, but unfortunately suffers from notorious domain shifts. In this work, we propose a Data-Oriented Domain Adaptation (DODA) framework to mitigate pattern and context gaps caused by different sensing mechanisms and layout placements across domains. Our DODA encompasses virtual scan simulation to imitate real-world point cloud patterns and tail-aware cuboid mixing to alleviate the interior context gap with a cuboid-based intermediate domain. The first unsupervised sim-to-real adaptation benchmark on 3D indoor semantic segmentation is also built on 3D-FRONT, ScanNet and S3DIS along with 8 popular Unsupervised Domain Adaptation (UDA) methods. Our DODA surpasses existing UDA approaches by over 13% on both 3D-FRONT → ScanNet and 3D-FRONT → S3DIS.
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Computational fluid dynamics study is performed to examine the effectiveness of two tripping methods including Hama strip and two-dimensional wire on laminar-to-turbulence boundary layer transition over 6:1 prolate spheroid. The c...
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Computational fluid dynamics study is performed to examine the effectiveness of two tripping methods including Hama strip and two-dimensional wire on laminar-to-turbulence boundary layer transition over 6:1 prolate spheroid. The correlation-based transition γ-Re_(θt) SST model that was previously implemented in an in-house CFD software and benchmarked against data for smooth surfaces is employed in the current study. Effect of trip thickness on the performance of both tripping techniques are investigated for a straight and level model at a range of flow speeds. Results indicate that a smaller thickness for Hama strip compared to wire is required to be effective at the same flow condition. Effect of tripping on boundary layer thickness and drag components are also examined. Numerical results are also validated against experimental data for smooth and wire tripped cases on Joubert model and reasonable agreement is achieved.
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Computational fluid dynamics study is performed to examine the effectiveness of two tripping methods including Hama strip and two-dimensional wire on laminar-to-turbulence boundary layer transition over 6:1 prolate spheroid. The c...
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Computational fluid dynamics study is performed to examine the effectiveness of two tripping methods including Hama strip and two-dimensional wire on laminar-to-turbulence boundary layer transition over 6:1 prolate spheroid. The correlation-based transition γ-Re_(θt) SST model that was previously implemented in an in-house CFD software and benchmarked against data for smooth surfaces is employed in the current study. Effect of trip thickness on the performance of both tripping techniques are investigated for a straight and level model at a range of flow speeds. Results indicate that a smaller thickness for Hama strip compared to wire is required to be effective at the same flow condition. Effect of tripping on boundary layer thickness and drag components are also examined. Numerical results are also validated against experimental data for smooth and wire tripped cases on Joubert model and reasonable agreement is achieved.
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This paper presents a high fidelity numerical analysis of boundary layer transition on a generic three-dimensional streamlined axisymmetric body. An in-house computational fluid dynamic software, which was previously validated for...
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This paper presents a high fidelity numerical analysis of boundary layer transition on a generic three-dimensional streamlined axisymmetric body. An in-house computational fluid dynamic software, which was previously validated for laminar-to-turbulence transition predictions, is employed to investigate a forced transition of boundary layer with Hama strip. Effectiveness of tripping with different thicknesses is examined on the flow at a range of speed and angle of attack, and a comparison is performed between forces, moment, and flow fields of un-tripped and tripped cases. In general, the effectiveness of tripping improves with the trip height and Reynolds number, while diminishes as the angle of attack increases. The results of un-tripped flow are also validated against published test data and reasonable correlations are obtained.
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In this paper, we present a framework for reconstructing a point-based 3D model of an object from a single-view image. We found distance metrics, like Chamfer distance, were used in previous work to measure the difference of two p...
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In this paper, we present a framework for reconstructing a point-based 3D model of an object from a single-view image. We found distance metrics, like Chamfer distance, were used in previous work to measure the difference of two point sets and serve as the loss function in point-based reconstruction. However, such point-point loss does not constrain the 3D model from a global perspective. We propose adding geometric adversarial loss (GAL). It is composed of two terms where the geometric loss ensures consistent shape of reconstructed 3D models close to ground-truth from different viewpoints, and the conditional adversarial loss generates a semantically-meaningful point cloud. GAL benefits predicting the obscured part of objects and maintaining geometric structure of the predicted 3D model. Both the qualitative results and quantitative analysis manifest the generality and suitability of our method.
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In this paper, we present a framework for reconstructing a point-based 3D model of an object from a single-view image. We found distance metrics, like Chamfer distance, were used in previous work to measure the difference of two p...
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In this paper, we present a framework for reconstructing a point-based 3D model of an object from a single-view image. We found distance metrics, like Chamfer distance, were used in previous work to measure the difference of two point sets and serve as the loss function in point-based reconstruction. However, such point-point loss does not constrain the 3D model from a global perspective. We propose adding geometric adversarial loss (GAL). It is composed of two terms where the geometric loss ensures consistent shape of reconstructed 3D models close to ground-truth from different viewpoints, and the conditional adversarial loss generates a semantically-meaningful point cloud. GAL benefits predicting the obscured part of objects and maintaining geometric structure of the predicted 3D model. Both the qualitative results and quantitative analysis manifest the generality and suitability of our method.
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With the growth of market competition on manufacture, milk-run becomes a popular just-in-time (JIT) logistic strategy to ensure vehicle pickups and delivers goods on multiple round trips with fixed time window. Reasonable milk-run...
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With the growth of market competition on manufacture, milk-run becomes a popular just-in-time (JIT) logistic strategy to ensure vehicle pickups and delivers goods on multiple round trips with fixed time window. Reasonable milk-run vehicle routing planning is able to improve the utilization of vehicle, so that logistic cost can be reduced. In order to better capture the real-world scenes, we build a novel milk-run model called MOPDPTW (Multiple-Orders Pickup and Delivery Problem with Time-bound Window) based on PDPTW (Pickup and Delivery Problem with Time Window). Aiming at minimizing the number of used vehicles and total travel distance in this model, a two-layers heuristic search algorithm is proposed to solve this problem. The inner layer of proposed algorithm searches possible solutions in global and sends them to the outer layer to find local optimal solution. We validate our algorithm against an improved large neighborhood algorithm on standard Li and Lim's benchmark and instances modified for MOPDPTW. The experiment results show that our algorithm performs better in reducing the logistic cost of milk-run.
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