2,920 research outputs found
A DYNAMIC EXERCISE IN REDUCING DEER-VEHICLE COLLISIONS: MANAGEMENT THROUGH VEHICLE MITIGATION TECHNIQUES AND HUNTING
The costs of deer-vehicle collisions (DVCs) nationwide are estimated to be in excess of $1 billion annually. In this study, factors contributing to the abundance of DVCs are identified and the potential effectiveness of various deer management strategies in reducing DVCs is investigated. The added benefits of such strategies are also evaluated in a bioeconomic context by comparing alternative outcomes achievable from implementing DVC mitigation techniques. Focusing on Ohio, results suggest potentially large economic gains exist from reducing DVCs, especially with strategies that combine both deer management schemes and DVC mitigation techniques.Resource /Energy Economics and Policy,
Autowaves in a dc complex plasma confined behind a de Laval nozzle
Experiments to explore stability conditions and topology of a dense
microparticle cloud supported against gravity by a gas flow were carried out.
By using a nozzle shaped glass insert within the glass tube of a dc discharge
plasma chamber a weakly ionized gas flow through a de Laval nozzle was
produced. The experiments were performed using neon gas at a pressure of 100 Pa
and melamine-formaldehyde particles with a diameter of 3.43 {\mu}m. The
capturing and stable global confining of the particles behind the nozzle in the
plasma were demonstrated. The particles inside the cloud behaved as a single
convection cell inhomogeneously structured along the nozzle axis in a tube-like
manner. The pulsed acceleration localized in the very head of the cloud
mediated by collective plasma-particle interactions and the resulting wave
pattern were studied in detail.Comment: 6 pages, 4 figure
Efficient data mappings for parity-declustered data layouts
AbstractThe joint demands of high performance and fault tolerance in a large array of disks can be satisfied by a parity-declustered data layout. Such a data layout is generated by partitioning the data on the disks into stripes and choosing a part of each stripe to hold redundant information. Thus the data layout can be represented as a table of stripes. The data mapping problem is the problem of translating a data address into a disk identifier and an offset on that disk. Recent work has yielded mappings that compute disks and offsets directly from data addresses without the need to store tables. In this paper, we show that parity-declustered data layouts based on commutative rings yield mappings with improved computational efficiency and wider applicability
Measurement of the speed of sound by observation of the Mach cones in a complex plasma under microgravity conditions
We report the first observation of the Mach cones excited by a larger
microparticle (projectile) moving through a cloud of smaller microparticles
(dust) in a complex plasma with neon as a buffer gas under microgravity
conditions. A collective motion of the dust particles occurs as propagation of
the contact discontinuity. The corresponding speed of sound was measured by a
special method of the Mach cone visualization. The measurement results are
incompatible with the theory of ion acoustic waves. The estimate for the
pressure in a strongly coupled Coulomb system and a scaling law for the complex
plasma make it possible to derive an evaluation for the speed of sound, which
is in a reasonable agreement with the experiments in complex plasmas.Comment: 5 pages, 2 figures, 1 tabl
Ordering of small particles in one-dimensional coherent structures by time-periodic flows
Small particles transported by a fluid medium do not necessarily have to
follow the flow. We show that for a wide class of time-periodic incompressible
flows inertial particles have a tendency to spontaneously align in
one-dimensional dynamic coherent structures. This effect may take place for
particles so small that often they would be expected to behave as passive
tracers and be used in PIV measurement technique. We link the particle tendency
to form one-dimensional structures to the nonlinear phenomenon of phase
locking. We propose that this general mechanism is, in particular, responsible
for the enigmatic formation of the `particle accumulation structures'
discovered experimentally in thermocapillary flows more than a decade ago and
unexplained until now
Experimental investigation of dynamical structures formation due to flowing complex plasma past an obstacle
We report the experimental observation of dynamical behavior of flowing
complex plasma past a spherical obstacle. The experiment has been carried out
in a -shaped DC glow discharge experimental device using kaolin particles
as the dust component in a background of Argon plasma. A stationary dust cloud
is formed by maintaining the pumping speed and gas flow rate. A spherical
obstacle vertically mounted on the cathode tray acts as an obstacle to the flow
of dust particles. The controlled dust flow is generated by reducing the mass
flow of the neutrals through a mass flow controller. The flowing dust particles
are repelled by the electrostatic field of the negatively charged sphere and a
microparticle free region (dust void) is formed surrounding the obstacle. The
far particles are attracted towards the floating obstacle and reflected back
when they have arrived at a minimum distance, causing a ring shaped structure
around the obstacle. We characterize the shape of this structure over a range
of dust flow speeds and obstacle biases. For a supersonic flow of dust fluid
around a negatively biased obstacle, a bow shock is formed on the upstream side
of the sphere, while the generation of wave structures is observed on the
downstream side for a particular range of flow velocities. Reynolds numbers in
this case is estimated as . This wave structure reminds of the
beginning of the formation of a Von-K\'arm\'an vortex street. A physical
picture for the observed structure based on ion-drag, neutral streaming and
electric forces is discussed.Comment: 9 pages, 7 figure
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