7,021 research outputs found
Hearing Waves: A Philosophy of Sound and Auditory Perception
This dissertation aims to revive wave theory in the philosophy of sound. Wave theory identifies sounds with compression waves. Despite its wide acceptance in the scientific community as the default position, many philosophers have rejected wave theory and opted for different versions of distal theory instead. According to this current majority view, a sound has its stationary location at its source. I argue against this and other alternative philosophical theories of sound and develop wave theory into a more defensible form.
Philosophers of sound tend to emphasise how sounds are experienced to be in their arguments. Most often, it is assumed that that which appears to be a distally located bearer of auditory properties in an auditory experience is a sound. Chapter 1 argues that if this distal entity is the sound source instead, many of the existing theories of sound will be severely affected.
Chapter 2 discusses auditory perception and criticises the common assumption that we hear non-sound entities in virtue of hearing sounds. I show that this assumption begs the question against certain theories of sound and that the contrary view that sound sources can be directly heard is more plausible.
If sound sources can be directly heard, then features commonly attributed to sounds based on auditory experiences might rather be features of sound sources. I examine eight of such features in Chapter 3. Only four of them survive.
Chapters 4 and 5 review the existing theories of sound. After a taxonomy of existing theories of sound, each theory is criticised one-by-one. Some of them are problematic precisely because they rely on the implausible assumption that that which appears to be distally located in an auditory experience is a sound rather than a sound source.
Lastly, Chapter 6 focuses on wave theory. It begins with two positive arguments for wave theory in general, followed by my replies to two common objections in the literature. I then move on to develop my version of wave theory. There are two core aspects of my view. The first one is a metaphysics of compression waves; the second is an account of what it is to hear compression waves. After comparing my view with a similar theory, I demonstrate the explanatory power of my view in two steps. First, the eight commonly accepted features of sounds examined in Chapter 3 are revisited. It turns out that my view can accommodate all of them. Second, explanations for four special sound-related phenomena are offered at the end of the chapter.
I conclude in the last chapter with the suggestion that, as a philosopher, the best way to defend wave theory is to offer a better understanding of auditory perception which explains how compression waves are experienced
The Radon Monitoring System in Daya Bay Reactor Neutrino Experiment
We developed a highly sensitive, reliable and portable automatic system
(H) to monitor the radon concentration of the underground experimental
halls of the Daya Bay Reactor Neutrino Experiment. H is able to measure
radon concentration with a statistical error less than 10\% in a 1-hour
measurement of dehumidified air (R.H. 5\% at 25C) with radon
concentration as low as 50 Bq/m. This is achieved by using a large radon
progeny collection chamber, semiconductor -particle detector with high
energy resolution, improved electronics and software. The integrated radon
monitoring system is highly customizable to operate in different run modes at
scheduled times and can be controlled remotely to sample radon in ambient air
or in water from the water pools where the antineutrino detectors are being
housed. The radon monitoring system has been running in the three experimental
halls of the Daya Bay Reactor Neutrino Experiment since November 2013
Structure formation in electromagnetically driven granular media
We report structure formation in submonolayers of magnetic microparticles
subjected to periodic electrostatic and magnetic excitations. Depending on the
excitation parameters, we observe the formation of a rich variety of
structures: clusters, rings, chains, and networks. The growth dynamics and
shapes of the structures are strongly dependent on the amplitude and frequency
of the external magnetic field. We find that for pure ac magnetic driving at
low densities of particles, the low-frequency magnetic excitation favors
clusters while high frequency excitation favors chains and net-like structures.
An abrupt phase transition from chains to a network phase was observed for a
high density of particles.Comment: 4 pages, 5 figure
An increase in under hydrostatic pressure in the superconducting doped topological insulator NbBiSe
We report an unexpected positive hydrostatic pressure derivative of the
superconducting transition temperature in the doped topological insulator \NBS
via SQUID magnetometry in pressures up to 0.6 GPa. This result is contrary
to reports on the homologues \CBS and \SBS where smooth suppression of is
observed. Our results are consistent with recent Ginzburg-Landau theory
predictions of a pressure-induced enhancement of in the nematic
multicomponent state proposed to explain observations of rotational
symmetry breaking in doped BiSe superconductors.Comment: 5 pages, 5 figure
Realization of Artificial Ice Systems for Magnetic Vortices in a Superconducting MoGe Thin-film with Patterned Nanostructures
We report an anomalous matching effect in MoGe thin films containing pairs of
circular holes arranged in such a way that four of those pairs meet at each
vertex point of a square lattice. A remarkably pronounced fractional matching
was observed in the magnetic field dependences of both the resistance and the
critical current. At the half matching field the critical current can be even
higher than that at zero field. This has never been observed before for
vortices in superconductors with pinning arrays. Numerical simulations within
the nonlinear Ginzburg-Landau theory reveal a square vortex ice configuration
in the ground state at the half matching field and demonstrate similar
characteristic features in the field dependence of the critical current,
confirming the experimental realization of an artificial ice system for
vortices for the first time.Comment: To appear in Phys. Rev. Let
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