205 research outputs found
Robusni algoritam praćenja mjerenjem smjera pomoću strukturiranog potpunog Kalmanovog filtra zasnovanog na metodi najmanjih kvadrata
A nonlinear approach called the robust structured total least squares kalman filter (RSTLS-KF) algorithm is proposed for solving tracking inaccuracy caused by outliers in bearings-only multi-station passive tracking. In that regard, the robust extremal function is introduced to the weighted structured total least squares (WSTLS) location criterion, and then the improved Danish equivalent weight function is built on the basis, which can identify outliers automatically and reduce the weight of the polluted data. Finally, the observation equation is linearized according to the RSTLS location result with the structured total least norm (STLN) solution. Hence location and velocity of the target can be given by the Kalman filter. Simulation results show that tracking performance of the RSTLS-KF is comparable or better than that of conventional algorithms. Furthermore, when outliers appear, the RSTLS-KF is accurate and robust, whereas the conventional algorithms become distort seriously.U ovome radu predložen je nelinearni pristup za rješavanje netočnosti uzrokovanih netipčnim vrijednostima kod praćenja mjerenjem smjera pasivnim senzorima s više stanica. Pristup je zasnovan na robusnom strukturiranom potpunom Kalmanovom filtru zasnovanom na metodi najmanjih kvadrata. Pomoću predložene metode moguće je estimirati položaj i brzinu praćenog objekta. Simulacijski rezultati pokazuju da je učinkovitost predloženog algoritma jednaka ili bolja od konvencionalnih algoritama. Nadalje, u prisustvu netipčnih vrijednosti mjerenja, predloženi algoritam zadržava točnost i robusnost, dok konvencionalni algoritmi pokazuju pogreške u estimaciji
High quality electrostatically defined hall bars in monolayer graphene
Realizing graphene's promise as an atomically thin and tunable platform for
fundamental studies and future applications in quantum transport requires the
ability to electrostatically define the geometry of the structure and control
the carrier concentration, without compromising the quality of the system.
Here, we demonstrate the working principle of a new generation of high quality
gate defined graphene samples, where the challenge of doing so in a gapless
semiconductor is overcome by using the insulating state, which emerges
at modest applied magnetic fields. In order to verify that the quality of our
devices is not compromised by the presence of multiple gates we compare the
electronic transport response of different sample geometries, paying close
attention to fragile quantum states, such as the fractional quantum Hall (FQH)
states, that are highly susceptible to disorder. The ability to define local
depletion regions without compromising device quality establishes a new
approach towards structuring graphene-based quantum transport devices
Nighttime Smartphone Reflective Flare Removal Using Optical Center Symmetry Prior
Reflective flare is a phenomenon that occurs when light reflects inside
lenses, causing bright spots or a "ghosting effect" in photos, which can impact
their quality. Eliminating reflective flare is highly desirable but
challenging. Many existing methods rely on manually designed features to detect
these bright spots, but they often fail to identify reflective flares created
by various types of light and may even mistakenly remove the light sources in
scenarios with multiple light sources. To address these challenges, we propose
an optical center symmetry prior, which suggests that the reflective flare and
light source are always symmetrical around the lens's optical center. This
prior helps to locate the reflective flare's proposal region more accurately
and can be applied to most smartphone cameras. Building on this prior, we
create the first reflective flare removal dataset called BracketFlare, which
contains diverse and realistic reflective flare patterns. We use continuous
bracketing to capture the reflective flare pattern in the underexposed image
and combine it with a normally exposed image to synthesize a pair of
flare-corrupted and flare-free images. With the dataset, neural networks can be
trained to remove the reflective flares effectively. Extensive experiments
demonstrate the effectiveness of our method on both synthetic and real-world
datasets.Comment: CVPR2023 (Highlight
Resonant TMR inversion in LiF/EuS based spin-filter tunnel junctions
Resonant tunneling can lead to inverse tunnel magnetoresistance when impurity
levels rather than direct tunneling dominate the transport process. We
fabricated hybrid magnetic tunnel junctions of CoFe/LiF/EuS/Ti, with an
epitaxial LiF energy barrier joined with a polycrystalline EuS spin-filter
bar-rier. Due to the water solubility of LiF, the devices were fully packaged
in situ. The devices showed sizeable positive TMR up to 16% at low bias
voltages but clearly inverted TMR at higher bias voltages. The TMR inversion
depends sensitively on the thickness of LiF, and the tendency of inversion
disap-pears when LiF gets thick enough and recovers its intrinsic properties
Surface modes in plasmonic Bragg fibers with negative average permittivity
We investigate surface modes in plasmonic Bragg fibers composed of
nanostructured coaxial cylindrical metal-dielectric multilayers. We demonstrate
that the existence of surface modes is determined by the sign of the spatially
averaged permittivity of the plasmonic Bragg fiber, \bar{% \varepsilon}.
Specifically, localized surface modes occur at the interface between the
cylindrical core with and the outermost uniform
dielectric medium, which is similar to the topologically protected plasmonic
surface modes at the interface between two different one-dimensional planar
metal-dielectric lattices with opposite signs of the averaged permittivity.
Moreover, when increasing the number of dielectric-metal rings, the propagation
constant of surface modes with different azimuthal mode numbers is approaching
that of surface plasmon polaritons formed at the corresponding planar
metal/dielectric interface. Robustness of such surface modes of plasmonic Bragg
fibers is demonstrated too.Comment: 10 pages, 5 figures, Optics Express, to be publishe
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