176 research outputs found
Sensitivity of lunar particle-detection experiments
The use of the Moon as a detector volume for ultra-high-energy neutrinos and
cosmic rays, by searching for the Askaryan radio pulse produced when they
interact in the lunar regolith, has been attempted by a range of projects over
the past two decades. In this contribution, I discuss some of the technical
considerations relevant to these experiments, and their consequent sensitivity
to ultra-high-energy particles. I also discuss some possible future
experiments, and highlight their potential.Comment: To be published in the Proceedings of the ARENA2016 conference,
Groningen, The Netherland
Investigation of variables for wireless capacitive strain sensing on a CNC mill
As demand in the manufacturing sector increases, so does the need for greater process throughput and reduced component variability. These two objectives can be achieved by a process known as \u27smart machining\u27. Smart machining utilizes sensors inside the machining environment to relay information to the machine controller. Most sensor systems adversely affect the machine dynamics, by reducing the machining envelope or reducing the machine\u27s stiffness, or require physical connections to conditioning electronics. In this research, variables regarding a resonantly coupled wireless capacitive strain sensor were investigated. A parallel plate capacitive sensor prototype system yielded a strain sensitivity five times greater than analytical predictions. Experimental investigations were performed on probe design, sensor design, and application dynamics. Computer simulations were performed for the change in capacitance of an interdigitated comb capacitor for simplified loading cases. Finally, a simplified resonance detection circuit attached to the probe loop was designed, assembled, and successfully tested
Limits on the validity of the thin-layer model of the ionosphere for radio interferometric calibration
For a ground-based radio interferometer observing at low frequencies, the
ionosphere causes propagation delays and refraction of cosmic radio waves which
result in phase errors in the received signal. These phase errors can be
corrected using a calibration method that assumes a two-dimensional phase
screen at a fixed altitude above the surface of the Earth, known as the
thin-layer model. Here we investigate the validity of the thin-layer model and
provide a simple equation with which users can check when this approximation
can be applied to observations for varying time of day, zenith angle,
interferometer latitude, baseline length, ionospheric electron content and
observing frequency.Comment: 8 pages, 10 figures, accepted MNRA
Spin-resolved electron-impact ionization of lithium
Electron-impact ionization of lithium is studied using the convergent
close-coupling (CCC) method at 25.4 and 54.4 eV. Particular attention is paid
to the spin-dependence of the ionization cross sections. Convergence is found
to be more rapid for the spin asymmetries, which are in good agreement with
experiment, than for the underlying cross sections. Comparison with the recent
measured and DS3C-calculated data of Streun et al (1999) is most intriguing.
Excellent agreement is found with the measured and calculated spin asymmetries,
yet the discrepancy between the CCC and DS3C cross sections is very large
Nonperturbative Functional Renormalization Group for Random Field Models. III: Superfield formalism and ground-state dominance
We reformulate the nonperturbative functional renormalization group for the
random field Ising model in a superfield formalism, extending the
supersymmetric description of the critical behavior of the system first
proposed by Parisi and Sourlas [Phys. Rev. Lett. 43, 744 (1979)]. We show that
the two crucial ingredients for this extension are the introduction of a
weighting factor, which accounts for ground-state dominance when multiple
metastable states are present, and of multiple copies of the original system,
which allows one to access the full functional dependence of the cumulants of
the renormalized disorder and to describe rare events. We then derive exact
renormalization group equations for the flow of the renormalized cumulants
associated with the effective average action.Comment: 28 page
Assessment of Information Needs, Perceived Importance and Preferences of Delivery Methods Among Selected Dairy Producers in Oklahoma
Pattern formation in self-propelled particles with density-dependent motility
We study the behaviour of interacting self-propelled particles, whose
self-propulsion speed decreases with their local density. By combining direct
simulations of the microscopic model with an analysis of the hydrodynamic
equations obtained by explicitly coarse graining the model, we show that
interactions lead generically to the formation of a host of patterns, including
moving clumps, active lanes and asters. This general mechanism could explain
many of the patterns seen in recent experiments and simulations
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