303 research outputs found
Sound field separation technique using the principle of double layer patch acoustic radiation modes
In order to solve the problems of near-field acoustic holography in applications such as external interference and aperture effects, a sound field separation technique using the principle of double layer patch acoustic radiation modes is proposed in this paper. The radiated acoustic pressures over two planar surfaces at certain distances from the sources are calculated first. Then, the effects resulting from the backscattering interference in non-free sound fields can be eliminated by a double-layer sound field separation technique. Next, data interpolation and extrapolation are performed on the separated data to increase the sound source's pressures on the holographic plane equivalently for holographic images with higher spatial resolution. Simulation and experimental results demonstrate that good agreements can be obtained with few measuring points
Nonlinear Transport of Graphene in the Quantum Hall Regime
We have studied the breakdown of the integer quantum Hall (QH) effect with
fully broken symmetry, in an ultra-high mobility graphene device sandwiched
between two single crystal hexagonal boron nitride substrates. The evolution
and stabilities of the QH states are studied quantitatively through the
nonlinear transport with dc Hall voltage bias. The mechanism of the QH
breakdown in graphene and the movement of the Fermi energy with the electrical
Hall field are discussed. This is the first study in which the stabilities of
fully symmetry broken QH states are probed all together. Our results raise the
possibility that the v=6 states might be a better target for the quantum
resistance standard.Comment: 15 pages,6 figure
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ICDP workshop on scientific drilling of Nam Co on the Tibetan Plateau: 1Â million years of paleoenvironmental history, geomicrobiology, tectonics and paleomagnetism derived from sediments of a high-altitude lake
The Tibetan Plateau is of peculiar societal relevance as it provides freshwater from the so-called “Water Tower of Asia” to a large portion of the Asian population. However, future climate change will affect the hydrological cycle in this area. To define parameters for future climate change scenarios it is necessary to improve the knowledge about thresholds, timing, pace and intensity of past climatic changes and associated environmental impacts. Sedimentary archives reaching far back in time and spanning several glacial–interglacial cycles such as Nam Co provide the unique possibility to extract such information. In order to explore the scientific opportunities that an ICDP drilling effort at Nam Co would provide, 40 scientists from 13 countries representing various scientific disciplines met in Beijing from 22 to 24 May 2018. Besides paleoclimatic investigations, opportunities for paleomagnetic, deep biosphere, tectonic and paleobiological studies were discussed. After having explored the technical and logistical challenges and the scientific opportunities all participants agreed on the great value and need to drill this extraordinary archive, which has a sediment thickness of more than 1 km, likely covering more than 1 Ma
RH20T: A Comprehensive Robotic Dataset for Learning Diverse Skills in One-Shot
A key challenge in robotic manipulation in open domains is how to acquire
diverse and generalizable skills for robots. Recent research in one-shot
imitation learning has shown promise in transferring trained policies to new
tasks based on demonstrations. This feature is attractive for enabling robots
to acquire new skills and improving task and motion planning. However, due to
limitations in the training dataset, the current focus of the community has
mainly been on simple cases, such as push or pick-place tasks, relying solely
on visual guidance. In reality, there are many complex skills, some of which
may even require both visual and tactile perception to solve. This paper aims
to unlock the potential for an agent to generalize to hundreds of real-world
skills with multi-modal perception. To achieve this, we have collected a
dataset comprising over 110,000 contact-rich robot manipulation sequences
across diverse skills, contexts, robots, and camera viewpoints, all collected
in the real world. Each sequence in the dataset includes visual, force, audio,
and action information. Moreover, we also provide a corresponding human
demonstration video and a language description for each robot sequence. We have
invested significant efforts in calibrating all the sensors and ensuring a
high-quality dataset. The dataset is made publicly available at rh20t.github.ioComment: RSS 2023 workshop on LTAMP. The project page is at rh20t.github.i
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