8,477 research outputs found
A V-Diagram for the Design of Integrated Health Management for Unmanned Aerial Systems
Designing Integrated Vehicle Health Management (IVHM) for Unmanned Aerial Systems (UAS) is inherently complex. UAS are a system of systems (SoS) and IVHM is a product-service, thus the designer has to take into account many factors, such as: the design of the other systems of the UAS (e.g. engines, structure, communications), the split of functions between elements of the UAS, the intended operation/mission of the UAS, the cost verses benefit of monitoring a system/component/part, different techniques for monitoring the health of the UAS, optimizing the health of the fleet and not just the individual UAS, amongst others. The design of IVHM cannot sit alongside, or after, the design of UAS, but itself be integrated into the overall design to maximize IVHM’s potential.
Many different methods exist to help design complex products and manage the process. One method used is the V-diagram which is based on three concepts: decomposition & definition; integration & testing; and verification & validation. This paper adapts the V-diagram so that it can be used for designing IVHM for UAS. The adapted v-diagram splits into different tracks for the different system elements of the UAS and responses to health states (decomposition and definition). These tracks are then combined into an overall IVHM provision for the UAS (integration and testing), which can be verified and validated. The stages of the adapted V-diagram can easily be aligned with the stages of the V-diagram being used to design the UAS bringing the design of the IVHM in step with the overall design process. The adapted V-diagram also allows the design IVHM for a UAS to be broken down in to smaller tasks which can be assigned to people/teams with the relevant competencies. The adapted V-diagram could also be used to design IVHM for other SoS and other vehicles or products
PAMELA's cosmic positron from decaying LSP in SO(10) SUSY GUT
We propose two viable scenarios explaining the recent observations on cosmic
positron excess. In both scenarios, the present relic density in the Universe
is assumed to be still supported by thermally produced WIMP or LSP (\chi). One
of the scenarios is based on two dark matter (DM) components (\chi,X) scenario,
and the other is on SO(10) SUSY GUT. In the two DM components scenario,
extremely small amount of non-thermally produced meta-stable DM component
[O(10^{-10}) < n_X /n_\chi] explains the cosmic positron excess. In the SO(10)
model, extremely small R-parity violation for LSP decay to e^\pm is naturally
achieved with a non-zero VEV of the superpartner of one right-handed neutrino
(\tilde{\nu}^c) and a global symmetry.Comment: 6 pages, Talks presented in PASCOS, SUSY, and COSMO/CosPA in 201
On magnetic leaf-wise intersections
In this article we introduce the notion of a magnetic leaf-wise intersection
point which is a generalization of the leaf-wise intersection point with
magnetic effects. We also prove the existence of magnetic leaf-wise
intersection points under certain topological assumptions.Comment: 43 page
BRST symmetry of SU(2) Yang-Mills theory in Cho--Faddeev--Niemi decomposition
We determine the nilpotent BRST and anti-BRST transformations for the
Cho--Faddeev-Niemi variables for the SU(2) Yang-Mills theory based on the new
interpretation given in the previous paper of the Cho--Faddeev-Niemi
decomposition. This gives a firm ground for performing the BRST quantization of
the Yang--Mills theory written in terms of the Cho--Faddeev-Niemi variables. We
propose also a modified version of the new Maximal Abelian gauge which could
play an important role in the reduction to the original Yang-Mills theory.Comment: 11 pages, no figure; Introduction improved, 3 references adde
Radion Dynamics and Phenomenology in the Linear Dilaton Model
We investigate the properties of the radion in the 5D linear dilaton model
arising from Little String Theory. A Goldberger-Wise type mechanism is used to
stabilise a large interbrane distance, with the dilaton now playing the role of
the stabilising field. We consider the coupled fluctuations of the metric and
dilaton fields and identify the physical scalar modes of the system. The
wavefunctions and masses of the radion and Kaluza-Klein modes are calculated,
giving a radion mass of order the curvature scale. As a result of the direct
coupling between the dilaton and Standard Model fields, the radion couples to
the SM Lagrangian, in addition to the trace of the energy-momentum tensor. The
effect of these additional interaction terms on the radion decay modes is
investigated, with a notable increase in the branching fraction to photons. We
also consider the effects of a non-minimal Higgs coupling to gravity, which
introduces a mixing between the Higgs and radion modes. Finally, we calculate
the production cross section of the radion at the LHC and use the current Higgs
searches to place constraints on the parameter space.Comment: 28 pages, 7 figures; v2: error in radion-gauge boson Feynman rules
corrected, version published in JHE
Room temperature spin coherence in ZnO
Time-resolved optical techniques are used to explore electron spin dynamics
in bulk and epilayer samples of n-type ZnO as a function of temperature and
magnetic field. The bulk sample yields a spin coherence time T2* of 20 ns at T
= 30 K. Epilayer samples, grown by pulsed laser deposition, show a maximum T2*
of 2 ns at T = 10 K, with spin precession persisting up to T = 280 K.Comment: 3 pages, 3 figure
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The Medium and the Backlash: The Disparagement of the #MeToo Movement in Online Public Discourse in South Korea
This study examines the #MeToo movement in South Korea to understand the role of online platforms in the development of a backlash discourse. We apply computational methods to analyze how the #MeToo movement was discussed by citizens on Twitter and in online news comments, in contrast to the traditional news media. Our findings show that the public discourse in user-driven online platforms enabled the proliferation of a disparaging narrative that challenged the movement, while the patterns of the backlash differed across platforms. Using word-embedding techniques and network analyses, we illustrate the shift in frames around #MeToo movement and highlight how platform affordances meaningfully shaped the way the backlash unfolded
How to hide a secret direction
We present a procedure to share a secret spatial direction in the absence of
a common reference frame using a multipartite quantum state. The procedure
guarantees that the parties can determine the direction if they perform joint
measurements on the state, but fail to do so if they restrict themselves to
local operations and classical communication (LOCC). We calculate the fidelity
for joint measurements, give bounds on the fidelity achievable by LOCC, and
prove that there is a non-vanishing gap between the two of them, even in the
limit of infinitely many copies. The robustness of the procedure under particle
loss is also studied. As a by-product we find bounds on the probability of
discriminating by LOCC between the invariant subspaces of total angular
momentum N/2 and N/2-1 in a system of N elementary spins.Comment: 4 pages, 1 figur
Log-law recovery through reinforcement-learning wall model for large-eddy simulation
This paper focuses on the use of reinforcement learning (RL) as a
machine-learning (ML) modeling tool for near-wall turbulence. RL has
demonstrated its effectiveness in solving high-dimensional problems, especially
in domains such as games. Despite its potential, RL is still not widely used
for turbulence modeling and is primarily used for flow control and optimization
purposes. A new RL wall model (WM) called VYBA23 is developed in this work,
which uses agents dispersed in the flow near the wall. The model is trained on
a single Reynolds number () and does not rely on high-fidelity
data, as the back-propagation process is based on a reward rather than output
error. The states of the RLWM, which are the representation of the environment
by the agents, are normalized to remove dependence on the Reynolds number. The
model is tested and compared to another RLWM (BK22) and to an equilibrium wall
model, in a half-channel flow at eleven different Reynolds numbers (). The effects of varying agents' parameters such as actions
range, time-step, and spacing are also studied. The results are promising,
showing little effect on the average flow field but some effect on wall-shear
stress fluctuations and velocity fluctuations. This work offers positive
prospects for developing RLWMs that can recover physical laws, and for
extending this type of ML models to more complex flows in the future.Comment: arXiv admin note: text overlap with arXiv:2211.0361
Immunocytochemical localization of casein kinase II during interphase and mitosis
We have developed specific antibodies to synthetic peptide antigens that react with the individual subunits of casein kinase II (CKII). Using these antibodies, we studied the localization of CKII in asynchronous HeLa cells by immunofluorescence and immunoelectron microscopy. Further studies were done on HeLa cells arrested at the G1/S transition by hydroxyurea treatment. Our results indicate that the CKII alpha and beta subunits are localized in the cytoplasm during interphase and are distributed throughout the cell during mitosis. Further electron microscopic investigation revealed that CKII alpha subunit is associated with spindle fibers during metaphase and anaphase. In contrast, the CKII alpha' subunit is localized in the nucleus during G1 and in the cytoplasm during S. Taken together, our results suggest that CKII may play significant roles in cell division control by shifting its localization between the cytoplasm and nucleus
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