398 research outputs found
WALLSY: The UWB and SmartMesh IP enabled Wireless Ad-hoc Low-power Localization SYstem
This paper follows the implementation of a proofof-concept localization system for GNSS-denied environments.
WALLSY (Wireless Ad-hoc Low-power Localization SYstem)
is a portable and modular Ultra Wide-Band (UWB) and Smart
Mesh IP (SMIP) hybrid. WALLSY uses UWB two way ranging
(TWR) to measure distances, which are then sent via the lowpower SMIP backbone network to a central hub for calculating
coordinates of tracked objects. The system is highly flexible and
requires no external infrastructure or prior knowledge of the
installation site. It uses a completely nomadic topology and
delivers high localization accuracy with all modules being
battery powered. It achieves this by using a custom time-slotting
protocol which maximizes deep-sleep mode for UWB. Battery
life can be further improved by activating inertial measurement
unit (IMU) filtering. Visualization of tracked objects and
system reconfiguration can be executed on-the-fly and are both
accessible to end users through a simple graphical user interface
(GUI). Results demonstrate that WALLSY can achieve more
than ten times longer battery lifetime compared to competing
solutions (localizing every 30 seconds). It provides 3D
coordinates with an average spatial error of 60.5cm and an
average standard deviation of 15cm. The system also provides
support for up to 20 tags
Flat-band energy analysis of the temperature-dependent superconducting gap for hydrogenated graphite fibers found from nonlocal electrical conductance experimental data
Experimental evidence of novel phenomena in hydrogenated graphite fibers is
found. An indirect excitonic mechanism is likely leading to a SC state below
the temperature Tc = 50 K, where the gap is divergent. Analysis of the gap
within the framework provided by the Bardeen-Cooper-Schrieffer (BCS) theory of
superconductivity shows that this is a multigap system. The energy gap data can
be better explained within the framework of topologically protected flat bands
applied to systems in which superconductivity occurs on the surface or at the
internal interfaces of the samples. The temperature dependence of the SC gap is
linear above 50 K. We use nonlocal differential conductance Gdiff(V) = dI(V)/dV
experimental data to show clear evidence of topological phenomena such as
interference of chiral asymmetric Andreev edge states and crossed Andreev
conversion. Gdiff(V) has a negative part that results from the nonlocal
coherence between electron and holes in the Andreev edge states. We conclude
that hydrogenated graphite bears the marks of an unconventional
high-temperature superconductor (HTSC).Comment: 5 pages, 7 figures. arXiv admin note: substantial text overlap with
arXiv:2005.0587
Magneto-structural phase transitions and two-dimensional spin waves in graphite
We have previously found experimental evidence for several quantum phenomena
in oxygen-ion implanted of hydrogenated graphite: ferromagnetism,
antiferromagnetism, paramagentism, triplet superconductivity, Andreev states,
Little-Parks oscillations, Lamb shift, Casimir effect, colossal
magnetoresistance, and topologically-protected flat-energy bands [1-6]. Triplet
superconductivity results in the formation of Josephson junctions, thus with
potential of being used for spintronics applications in the critical area of
quantum computing. In this paper, we are showing new experimental evidence for
the formation of two-dimensional (2D) spin waves in oxygen-ion enriched and in
hydrogenated highly oriented pyrolytic graphite. The temperature evolution of
the remanent magnetization Mrem(T) data confirms the formation of spin waves
that follow the 2D Heisenberg model with a weak uniaxial anisotropy. In
addition, the step-like features also found in the temperature dependence of
the electrical resistivity between insulating and metallic states suggest
several outstanding possibilities, such as a structural transition, triplet
superconductivity, and chiral properties.Comment: 8 pages,7 figures, accepted by the Conference Editors for the
CEC-ICMC 2023 Conference for publication in the IOP Conference Series:
Materials Science and Engineering, Advances in Cryogenic Engineerin
QUANTIFYING FIT IN ICE HOCKEY SKATE BOOTS
Skates are specifically designed for the hockey game context. It is vital that skates be chosen in relation with proper size and shape, as well as with respect to play style and position (Pearsall et al. 2000). To provide optimal function, they must "fit". Fit infers many traits: to fit snugly around the contours of the bony ankle and foot structures, to provide stability, and to avoid discomfort. Nonetheless, players have often sacrificed "fit for comfort" at the expense of "fit for performance". Comfort and fit are interrelated qualities and important factors for footwear in recreational and physical activities. Increasing interest in footwear comfort resulted in several investigations that associated comfort with plantar pressure distribution (Chen et al.1994). To date, improved ratings for shoes comfort can be done by adding a control condition to the testing protocol and using a visual analog scale (VAS) to assess comfort (Mundermann et al. 2002). Little have been done in assessing fit in ice hockey boots. The purpose of this study is to quantify fit in the ice hockey skate boots by means of pressure distribution measures in conjunction with perceptual VAS ratings
Multipartite Entanglement Evolution Under Separable Operations
We study how multi-partite entanglement evolves under the paradigm of
separable operations, which include the local operations and classical
communication (LOCC) as a special case. We prove that the average "decay" of
entanglement induced by a separable operation is measure independent (among
SL-invariant ones) and state independent: the ratio between the average output
entanglement and the initial entanglement is solely a function of the separable
operation, regardless of the input state and of the SL-invariant entanglement
measure being used. We discuss the "disentangling power" of a quantum channel
and show that it exhibits a similar state invariance as the average
entanglement decay ratio. Our Rapid Communication significantly extends the
bipartite results of Ref. [1-3] as well as the multi-partite one of Ref. [4],
all of the previous work being restricted to one-sided or particular noise
models.Comment: Replaced by the published version, comments are welcome
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