1,271 research outputs found
Research on the near field sound source localization method for small snapshots
The performance of standard MVDR algorithm would be decreased sharply when the sampled data is small. In this paper, vector MVDR algorithm and the diagonal loading are proposed to improve the robustness. Firstly, the sample date covariance matrix is whitened to obtain more uniform noise, and then use the standard deviation of covariance matrix as the loading amount to complete diagonal loading. Finally, the effectiveness and robustness of the proposed algorithm is verified by simulation. Simulation results reveal that it has higher positioning accuracy with small sample, with the increase of SNR and snapshots, the estimation’s RMSE of target location decreases continuously
Quantized Feedback Control of Network Empowerment Ammunition with Data-Rate Limitations
This paper investigates quantized feedback control problems for network empowerment ammunition, where the sensors and the controller are connected by a digital communication network with data-rate limitations. Different from the existing ones, a new bit-allocation algorithm on the basis of the singular values of the plant matrix is proposed to encode the plant states. A lower bound on the data rate is presented to ensure stabilization of the unstable plant. It is shown in our results that, the algorithm can be employed for the more general case. An illustrative example is given to demonstrate the effectiveness of the proposed algorithm
Ultrafast fluorescent decay induced by metal-mediated dipole-dipole interaction in two-dimensional molecular aggregates
Two-dimensional molecular aggregate (2DMA), a thin sheet of strongly
interacting dipole molecules self-assembled at close distance on an ordered
lattice, is a fascinating fluorescent material. It is distinctively different
from the single or colloidal dye molecules or quantum dots in most previous
research. In this paper, we verify for the first time that when a 2DMA is
placed at a nanometric distance from a metallic substrate, the strong and
coherent interaction between the dipoles inside the 2DMA dominates its
fluorescent decay at picosecond timescale. Our streak-camera lifetime
measurement and interacting lattice-dipole calculation reveal that the
metal-mediated dipole-dipole interaction shortens the fluorescent lifetime to
about one half and increases the energy dissipation rate by ten times than
expected from the noninteracting single-dipole picture. Our finding can enrich
our understanding of nanoscale energy transfer in molecular excitonic systems
and may designate a new direction for developing fast and efficient
optoelectronic devices.Comment: 9 pages, 6 figure
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High reward enhances perceptual learning.
Studies of perceptual learning have revealed a great deal of plasticity in adult humans. In this study, we systematically investigated the effects and mechanisms of several forms (trial-by-trial, block, and session rewards) and levels (no, low, high, subliminal) of monetary reward on the rate, magnitude, and generalizability of perceptual learning. We found that high monetary reward can greatly promote the rate and boost the magnitude of learning and enhance performance in untrained spatial frequencies and eye without changing interocular, interlocation, and interdirection transfer indices. High reward per se made unique contributions to the enhanced learning through improved internal noise reduction. Furthermore, the effects of high reward on perceptual learning occurred in a range of perceptual tasks. The results may have major implications for the understanding of the nature of the learning rule in perceptual learning and for the use of reward to enhance perceptual learning in practical applications
Electromagnetic counterparts of high-frequency gravitational waves in a rotating laboratory frame system and their detection
We consider the perturbative photon flows (PPFs, i.e., electromagnetic (EM)
counterparts) generated by the EM resonance response to high-frequency
gravitational waves (HFGWs) with additional polarization states in a rotating
laboratory frame system. It is found that when the propagating direction of the
HFGWs and the symmetrical axis of the laboratory frame system are the same, the
PPFs have the maximum value. In this case, using the rotation (the rotation of
azimuth ) of the EM detection system, all six possible polarization
states of the HFGWs can be separated and displayed. For the current
experimental conditions, it is quite prospective to detect the PPFs generated
by the HFGWs predicted in the braneworld models, the primordial black hole
theories and the interaction mechanism between astrophysical plasma and intense
EM radiation, etc., due to the large amplitudes (or high spectral densities)
and spectral characteristics of these HFGWs. Detecting the primordial HFGWs
from inflation faces great challenges at present, but it is not impossible.Comment: 29 pages, 8 figures, 1 table; corrected some minor typos; added
reference
4-(4-Pentylcyclohexyl)phenol
In the title compound, C17H26O, the cyclohexyl ring adopts a chair conformation with the C-atom substituents in equatorial sites. The H atom of the O—H group is disordered over two positions of equal occupancy. In the crystal, O—H⋯O hydrogen bonds lead to [010] chains
5-(Pyridin-4-yl)isophthalic acid
In the title compound, C13H9NO4, the two carboxylic groups and the benzene ring are approximately co-planar with a maximum atomic deviation 0.175 (4) Å, while the pyridine ring is oriented at a dihedral angle of 31.07 (18)° with respect to the benzene ring. In the crystal, molecules are linked by O—H⋯O, O—H⋯N and weak C—H⋯O hydrogen bonds, forming a three-dimensional supramolecular framework
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