11,616 research outputs found
Learning to Place New Objects
The ability to place objects in the environment is an important skill for a
personal robot. An object should not only be placed stably, but should also be
placed in its preferred location/orientation. For instance, a plate is
preferred to be inserted vertically into the slot of a dish-rack as compared to
be placed horizontally in it. Unstructured environments such as homes have a
large variety of object types as well as of placing areas. Therefore our
algorithms should be able to handle placing new object types and new placing
areas. These reasons make placing a challenging manipulation task. In this
work, we propose a supervised learning algorithm for finding good placements
given the point-clouds of the object and the placing area. It learns to combine
the features that capture support, stability and preferred placements using a
shared sparsity structure in the parameters. Even when neither the object nor
the placing area is seen previously in the training set, our algorithm predicts
good placements. In extensive experiments, our method enables the robot to
stably place several new objects in several new placing areas with 98%
success-rate; and it placed the objects in their preferred placements in 92% of
the cases
Computational Aerodynamics on unstructed meshes
New 2D and 3D unstructured-grid based flow solvers have been developed for simulating steady compressible flows for aerodynamic applications. The codes employ the full compressible Euler/Navier-Stokes equations. The Spalart-Al Imaras one equation turbulence model is used to model turbulence effects of flows. The spatial discretisation has been obtained using a cell-centred finite volume scheme on unstructured-grids, consisting of triangles in 2D and of tetrahedral and prismatic elements in 3D. The temporal discretisation has been obtained with an explicit multistage Runge-Kutta scheme. An "inflation" mesh generation technique is introduced to effectively reduce the difficulty in generating highly stretched 2D/3D viscous grids in regions near solid surfaces. The explicit flow method is accelerated by the use of a multigrid method with consideration of the high grid aspect ratio in viscous flow simulations. A solution mesh adaptation technique is incorporated to improve the overall accuracy of the 2D inviscid and viscous flow solutions. The 3D flow solvers are parallelised in a MIMD fashion aimed at a PC cluster system to reduce the computing time for aerodynamic applications. The numerical methods are first applied to several 2D inviscid flow cases, including subsonic flow in a bump channel, transonic flow around a NACA0012 airfoil and transonic flow around the RAE 2822 airfoil to validate the numerical algorithms. The rest of the 2D case studies concentrate on viscous flow simulations including laminar/turbulent flow over a flat plate, transonic turbulent flow over the RAE 2822 airfoil, and low speed turbulent flows in a turbine cascade with massive separations. The results are compared to experimental data to assess the accuracy of the method. The over resolved problem with mesh adaptation on viscous flow simulations is addressed with a two phase mesh reconstruction procedure. The solution convergence rate with the aspect ratio adaptive multigrid method and the direct connectivity based multigrid is assessed in several viscous turbulent flow simulations. Several 3D test cases are presented to validate the numerical algorithms for solving Euler/Navier-Stokes equations. Inviscid flow around the M6 wing airfoil is simulated on the tetrahedron based 3D flow solver with an upwind scheme and spatial second order finite volume method. The efficiency of the multigrid for inviscid flow simulations is examined. The efficiency of the parallelised 3D flow solver and the PC cluster system is assessed with simulations of the same case with different partitioning schemes. The present parallelised 3D flow solvers on the PC cluster system show satisfactory parallel computing performance. Turbulent flows over a flat plate are simulated with the tetrahedron based and prismatic based flow solver to validate the viscous term treatment. Next, simulation of turbulent flow over the M6 wing is carried out with the parallelised 3D flow solvers to demonstrate the overall accuracy of the algorithms and the efficiency of the multigrid method. The results show very good agreement with experimental data. A highly stretched and well-formed computational grid near the solid wall and wake regions is generated with the "inflation" method. The aspect ratio adaptive multigrid displayed a good acceleration rate. Finally, low speed flow around the NREL Phase 11 Wind turbine is simulated and the results are compared to the experimental data
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China’s new Foreign Investment Law: deeper reform and more trust are needed
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Zen Design: Applying Zen Principles to Brand Identity in Contemporary Graphic Design
Relaxing and finding inner balance is extremely important to those of us who live in a fast-paced, modern world. Zen has become more and more popular in different cultures and we can see the shadows of it in many of the products we interact with and use in daily life. It is being used in branding intentionally and unintentionally in some form but very few of these efforts are effective.
Through research and informational analysis, this thesis provides a simple way to understand Zen principles from psychological and aesthetic perspectives, and also identifies the similarities and differences between Modernism and Zen. A case study was also conducted on an experimental brand to explore the possibility of applying Zen principles to Brand Identity in Contemporary Graphic Design. A brand manual was created using the knowledge and findings gathered through research. The project integrates research, informational poster design, and brand identity design
Steering between Bloch oscillation and dipole oscillation in parabolic optical waveguide arrays
We study the optical oscillations of supermodes in planar optical waveguide
arrays with parabolically graded propagation constant in individual waveguide
interacting through nearest neighbor couplings. In these arrays, we have
identified a transition between a symmetric dipole oscillation (DO) and a
symmetry-breaking Bloch oscillation (BO) under appropriate conditions. There
exist obvious correspondences between gradon localization and various optical
oscillations. By virtue of an analogue between the oscillation of optical
system and that of a plane pendulum, we propose a shift of the graded profile
to cause a transition from BO to DO. We confirm the optical transition by means
of Hamiltonian optics, as well as by the field evolution of the supermodes. The
results offer great potential applications in optical switching, which can be
applied to design suitable optical devices.Comment: Submitted to JOSA B for publication
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