603 research outputs found
Vortexje - An Open-Source Panel Method for Co-Simulation
This paper discusses the use of the 3-dimensional panel method for dynamical
system simulation. Specifically, the advantages and disadvantages of model
exchange versus co-simulation of the aerodynamics and the dynamical system
model are discussed. Based on a trade-off analysis, a set of recommendations
for a panel method implementation and for a co-simulation environment is
proposed. These recommendations are implemented in a C++ library, offered
on-line under an open source license. This code is validated against XFLR5, and
its suitability for co-simulation is demonstrated with an example of a tethered
wing, i.e, a kite. The panel method implementation and the co-simulation
environment are shown to be able to solve this stiff problem in a stable
fashion.Comment: 13 pages, 8 figure
Tracking control with adaption of kites
A novel tracking paradigm for flying geometric trajectories using tethered
kites is presented. It is shown how the differential-geometric notion of
turning angle can be used as a one-dimensional representation of the kite
trajectory, and how this leads to a single-input single-output (SISO) tracking
problem. Based on this principle a Lyapunov-based nonlinear adaptive controller
is developed that only needs control derivatives of the kite aerodynamic model.
The resulting controller is validated using simulations with a point-mass kite
model.Comment: 20 pages, 12 figure
Work Roll Cooling System Design Optimisation in Presence of Uncertainty
Organised by: Cranfield UniversityThe paper presents a framework to optimise the design of work roll based on the cooling performance. The
framework develops Meta models from a set of Finite Element Analysis (FEA) of the roll cooling. A design of
experiment technique is used to identify the FEA runs. The research also identifies sources of uncertainties
in the design process. A robust evolutionary multi-objective algorithm is applied to the design optimisation I
order to identify a set of good solutions in the presence of uncertainties both in the decision and objective
spaces.Mori Seiki â The Machine Tool Compan
Primary hemochromatosis presented by porphyria cutanea tarda: a case report
We present a 27-year-old female Caucasian patient, who initially presented with extensive fragility and blistering of mainly the dorsal side of both hands. Histology and urine porphyrin analysis confirmed the diagnosis of porphyria cutanea tarda. Internal screening for underlying disease revealed C282Y mutation-associated primary hemochromatosis, a hereditary iron-overload syndrome that may cause toxicity of a variety of organs. Hemochromatosis and porphyria cutanea tarda are pathogenetically linked as iron interferes with heme synthesis pathway. Patient was successfully treated with phlebotomy and low-dose hydroxychloroquine
Coexistence of Fermi arcs with two-dimensional gapless Dirac states
We present a physical scenario in which both Fermi arcs and two-dimensional gapless Dirac states coexist as boundary modes at the same two-dimensional surface. This situation is realized in topological insulatorâWeyl semimetal interfaces in spite of explicit time-reversal symmetry breaking. Based on a heuristic topological index, we predict that the coexistence is allowed when (i) the corresponding states of the Weyl semimetal and topological insulator occur at disconnected parts of the Brillouin zone separated by the Weyl nodes and (ii) the time-reversal breaking vector defining the Weyl semimetal has no projection parallel to the domain wall. This is corroborated by a numerical simulation of a tight binding model. We further calculate the optical conductivity of the coexisting interface states, which can be used to identify them through interference experiments
Political Identity Rules: Support of Renewable Energy Jobs and Attitudes on Soil Conservation in Northeastern Ohio
The purpose of this study was to look at the support of a proposed Act and renewable energy jobs as it paired with endorsement from elite Republicans. This was tested across political groups but mainly focuses on Republican responses. The hypothesis was that with elite endorsement Republican approval will increase for both the Act and renewable energy jobs. This study also focuses on attitudes of local farmers in Northeastern Ohio on soil conservation and how Republican values and identity politics affect this. This was studied through both a survey of approximately 450 people and through archival work. The results indicate that elite endorsement did not increase support for either the Act or renewable energy jobs within the Republican sample. Democrats and Independents responses actually increased support for the Act even with Republican endorsement. Additionally, while endorsement does not increase support, within this sample, support for both was relatively high. Both the Act and jobs are predictable by political identification, this is also a stronger predictor than the prime (elite endorsement). The archival research found that racial identity politics catalyze political beliefs already held by many local farmers which intensifies their desire to not have their farming be governed, which includes how they treat their soil
Spectral and Timing Nature of the Symbiotic X-ray Binary 4U 1954+319: The Slowest Rotating Neutron Star in an X-ray Binary System
The symbiotic X-ray binary 4U 1954+319 is a rare system hosting a peculiar
neutron star (NS) and an M-type optical companion. Its ~5.4h NS spin period is
the longest among all known accretion-powered pulsars and exhibited large (~7%)
fluctuations over 8 years. A spin trend transition was detected with Swift/BAT
around an X-ray brightening in 2012. The source was in quiescent and bright
states before and after this outburst based on 60 ks Suzaku observations in
2011 and 2012. The observed continuum is well described by a Comptonized model
with the addition of a narrow 6.4 keV Fe Kalpha line during the outburst.
Spectral similarities to slowly rotating pulsars in high-mass X-ray binaries,
its high pulsed fraction (~60-80%), and the location in the Corbet diagram
favor high B-field (>~1e+12 G) over a weak field as in low-mass X-ray binaries.
The observed low X-ray luminosity (1e+33-1e+35 erg/s), probable wide orbit, and
a slow stellar wind of this SyXB make quasi-spherical accretion in the subsonic
settling regime a plausible model. Assuming a ~1e+13 G NS, this scheme can
explain the ~5.4 h equilibrium rotation without employing the magnetar-like
field (~1e+16 G) required in the disk accretion case. The time-scales of
multiple irregular flares (~50 s) can also be attributed to the free-fall time
from the Alfven shell for a ~1e+13 G field. A physical interpretation of SyXBs
beyond the canonical binary classifications is discussed.Comment: 20 pages, 18 figures, 3 tables, accepted for publication in the
Astrophysical Journa
Service Selection using Predictive Models and Monte-Carlo Tree Search
This article proposes a method for automated service selection to improve
treatment efficacy and reduce re-hospitalization costs. A predictive model is
developed using the National Home and Hospice Care Survey (NHHCS) dataset to
quantify the effect of care services on the risk of re-hospitalization. By
taking the patient's characteristics and other selected services into account,
the model is able to indicate the overall effectiveness of a combination of
services for a specific NHHCS patient. The developed model is incorporated in
Monte-Carlo Tree Search (MCTS) to determine optimal combinations of services
that minimize the risk of emergency re-hospitalization. MCTS serves as a risk
minimization algorithm in this case, using the predictive model for guidance
during the search. Using this method on the NHHCS dataset, a significant
reduction in risk of re-hospitalization is observed compared to the original
selections made by clinicians. An 11.89 percentage points risk reduction is
achieved on average. Higher reductions of roughly 40 percentage points on
average are observed for NHHCS patients in the highest risk categories. These
results seem to indicate that there is enormous potential for improving service
selection in the near future
- âŠ