1,715 research outputs found
Silicon Carbide-Based Hydrogen and Hydrocarbon Gas Detection
Hydrogen and hydrocarbon detection in aeronautical applications is important for reasons of safety and emissions control. The use of silicon carbide as a semiconductor in a metal-semiconductor or metal-insulator-semiconductor structure opens opportunities to measure hydrogen and hydrocarbons in high temperature environments beyond the capabilities of silicon-based devices. The purpose of this paper is to explore the response and stability of Pd-SiC Schottky diodes as gas sensors in the temperature range from 100 to 400 C. The effect of heat treating on the diode properties as measured at 100 C is explored. Subsequent operation at 400 C demonstrates the diodes' sensitivity to hydrogen and hydrocarbons. It is concluded that the Pd-SiC Schottky diode has potential as a hydrogen and hydrocarbon sensor over a wide range of temperatures but further studies are necessary to determine the diodes' long term stability
Identifying user preferences for a digital educational solution for young seniors with diabetes
The Eindhoven Diabetes Education Simulator project was initiated to develop an educational solution that helps diabetes patients understand and learn more about their diabetes. This article describes the identification of user preferences for the development of such solutions. Young seniors (aged 50-65 years) with type 2 diabetes were chosen as the target group because they are likely to have more affinity with digital devices than older people and because 88% of the Dutch diabetes population is > 50 years of age. Data about the target group were gathered through literature research and interviews. The literature research covered data about their device use and education preferences. To gain insight into the daily life of diabetes patients and current diabetes education processes, 20 diabetes patients and 10 medical experts were interviewed. The interviews were analyzed using affinity diagrams. Those diagrams, together with the literature data, formed the basis for two personas and corresponding customer journey maps. Literature showed that diabetes prevalence is inversely correlated to educational level. Computer and device use is relatively low within the target group, but is growing. The interviews showed that young seniors like to play board, card, and computer games, with others or alone. Family and loved ones play an important role in their lives. Medical experts are crucial in the diabetes education of young senior diabetes patients. These findings are translated into a list of design aspects that can be used for creating educational solutions
Voronoi-Delaunay analysis of normal modes in a simple model glass
We combine a conventional harmonic analysis of vibrations in a one-atomic
model glass of soft spheres with a Voronoi-Delaunay geometrical analysis of the
structure. ``Structure potentials'' (tetragonality, sphericity or perfectness)
are introduced to describe the shape of the local atomic configurations
(Delaunay simplices) as function of the atomic coordinates. Apart from the
highest and lowest frequencies the amplitude weighted ``structure potential''
varies only little with frequency. The movement of atoms in soft modes causes
transitions between different ``perfect'' realizations of local structure. As
for the potential energy a dynamic matrix can be defined for the ``structure
potential''. Its expectation value with respect to the vibrational modes
increases nearly linearly with frequency and shows a clear indication of the
boson peak. The structure eigenvectors of this dynamical matrix are strongly
correlated to the vibrational ones. Four subgroups of modes can be
distinguished
A batch-service queueing model with a discrete batch Markovian arrival process
Queueing systems with batch service have been investigated extensively during the past decades. However, nearly all the studied models share the common feature that an uncorrelated arrival process is considered, which is unrealistic in several real-life situations. In this paper, we study a discrete-time queueing model, with a server that only initiates service when the amount of customers in system (system content) reaches or exceeds a threshold. Correlation is taken into account by assuming a discrete batch Markovian arrival process (D-BMAP), i.e. the distribution of the number of customer arrivals per slot depends on a background state which is determined by a first-order Markov chain. We deduce the probability generating function of the system content at random slot marks and we examine the influence of correlation in the arrival process on the behavior of the system. We show that correlation merely has a small impact on the threshold that minimizes the mean system content. In addition, we demonstrate that correlation might have a significant influence on the system content and therefore has to be included in the model
Observation of Parity Violation in the Omega-minus -> Lambda + K-minus Decay
The alpha decay parameter in the process Omega-minus -> Lambda + K-minus has
been measured from a sample of 4.50 million unpolarized Omega-minus decays
recorded by the HyperCP (E871) experiment at Fermilab and found to be [1.78 +/-
0.19(stat) +/- 0.16(syst)]{\times}10^{-2}. This is the first unambiguous
evidence for a nonzero alpha decay parameter, and hence parity violation, in
the Omega-minus -> Lambda + K-minus decay.Comment: 10 pages, 7 figure
Large-scale Bright Fronts in the Solar Corona: A Review of "EIT waves"
``EIT waves" are large-scale coronal bright fronts (CBFs) that were first
observed in 195 \AA\ images obtained using the Extreme-ultraviolet Imaging
Telescope (EIT) onboard the \emph{Solar and Heliospheric Observatory (SOHO)}.
Commonly called ``EIT waves", CBFs typically appear as diffuse fronts that
propagate pseudo-radially across the solar disk at velocities of 100--700 km
s with front widths of 50-100 Mm. As their speed is greater than the
quiet coronal sound speed (200 km s) and comparable to the
local Alfv\'{e}n speed (1000 km s), they were initially
interpreted as fast-mode magnetoacoustic waves ().
Their propagation is now known to be modified by regions where the magnetosonic
sound speed varies, such as active regions and coronal holes, but there is also
evidence for stationary CBFs at coronal hole boundaries. The latter has led to
the suggestion that they may be a manifestation of a processes such as Joule
heating or magnetic reconnection, rather than a wave-related phenomena. While
the general morphological and kinematic properties of CBFs and their
association with coronal mass ejections have now been well described, there are
many questions regarding their excitation and propagation. In particular, the
theoretical interpretation of these enigmatic events as magnetohydrodynamic
waves or due to changes in magnetic topology remains the topic of much debate.Comment: 34 pages, 19 figure
HyperCP: A high-rate spectrometer for the study of charged hyperon and kaon decays
The HyperCP experiment (Fermilab E871) was designed to search for rare
phenomena in the decays of charged strange particles, in particular CP
violation in and hyperon decays with a sensitivity of
. Intense charged secondary beams were produced by 800 GeV/c protons
and momentum-selected by a magnetic channel. Decay products were detected in a
large-acceptance, high-rate magnetic spectrometer using multiwire proportional
chambers, trigger hodoscopes, a hadronic calorimeter, and a muon-detection
system. Nearly identical acceptances and efficiencies for hyperons and
antihyperons decaying within an evacuated volume were achieved by reversing the
polarities of the channel and spectrometer magnets. A high-rate
data-acquisition system enabled 231 billion events to be recorded in twelve
months of data-taking.Comment: 107 pages, 45 Postscript figures, 14 tables, Elsevier LaTeX,
submitted to Nucl. Instrum. Meth.
Quasifree eta photoproduction from nuclei and medium modifications of resonances
We investigate the sensitivity of the differential cross section, recoil
nucleon polarization and the photon asymmetry to changes in the elementary
amplitude, medium modifications of the resonance masses, as
well as nuclear target effects. All calculations are performed within a
relativistic plane wave impulse approximation formalism resulting in analytical
expressions for all observables. The spin observables are shown to be unique
tools to study subtle effects that are not accessible by only looking at the
unpolarized differential cross section.Comment: 27 pages, 8 figures, Revtex, To be published in Phys. Rev.
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