3,189 research outputs found
Interim report on the progress of an inventory of artesian wells in Florida: leading to the enforcement of sections 370.051 - 370.54, Florida statues
One of the causes of lower artesian pressure, water
waste and aquifer contamination is the misuse and insufficient
care of artesian wells. In 1953, Senate Bill No. 57, entitled
"An Act to Protect and Control the Artesian Waters of the
State" (see Appendix) became a law. This law was passed
through the efforts exerted by leading members of the Senate
and the House of Representatives, who understood the need
for a wise and controlled expenditure of our most valuable
natural resource.
The State Geologist and his authorized representatives
were designated by this law to enforce this conservation
measure; however, no financial provision was included for
the 1953-55 biennium. The proposed program of the Florida
Geological Survey for this biennium did not include the funds
nor provide any full-time personnel for the enforcement of
this statute. As a result, little actual work was accomplished during these two years, although much time was given to
planning and discussion of the problem.
Realizing that this program could provide additional basic
data needed in the analysis of the water-supply problem, the
State Geologist sought and was granted by the 1955 Legislature
adequate funds with which to activate the first phase of the
enforcement of Florida Statute No. 370.051-054.
Enumerated below is a summary of the progress made
on this investigation as outlined previously:
1. Data have been collected on 967 wildly flowing wells
in 22 counties.
2. Chloride determinations have been run on 850 of the
967 wells.
3. Of the 967 wells, 554 have chlorides in excess of the
250 ppm, the upper limit assigned by the State Board
of Health for public consumption.
4. Water escapes at the rate of 37, 762 gallons per minute
from these 967 wells. This amounts to 54, 377, 280
gallons per day.
The investigation is incomplete at this time; therefore,
no final conclusions can be reached. However, from data
already collected, the following recommendations are proposed:
1. That the present inventory of wildly flowing wells be
completed for the entire State.
2. That the current inventory of wildly flowing wells be
expanded at the conclusion of the present inventory
to include all flowing wells.
3. That a complete statewide inventory program be
established and conducted in cooperation with the
Ground Water Branchof the U.S. Geological Survey.
4. That the enforcement functions as set down in Sections
370.051/.054, Florida Statutes, be separated from
the program to collect water-resource data and that
these functions be given to the Water Resources
Department, if such is created (to be recommended
by the Water Resources Study Commission in a water
policy law presented to the 1957 Legislature).
5. That the research phase (well inventory) of the program
remain under the direction of the Florida Geological
Survey. (PDF contains 204 pages.
Non-linear resistivity and heat dissipation in monolayer graphene
We have experimentally studied the nonlinear nature of electrical conduction
in monolayer graphene devices on silica substrates. This nonlinearity manifests
itself as a nonmonotonic dependence of the differential resistance on applied
DC voltage bias across the sample. At temperatures below ~70K, the differential
resistance exhibits a peak near zero bias that can be attributed to
self-heating of the charge carriers. We show that the shape of this peak arises
from a combination of different energy dissipation mechanisms of the carriers.
The energy dissipation at higher carrier temperatures depends critically on the
length of the sample. For samples longer than 10um the heat loss is shown to be
determined by optical phonons at the silica-graphene interface.Comment: 4 pages, 4 figure
Strong nonlinear optical response of graphene flakes measured by four-wave mixing
We present the first experimental investigation of nonlinear optical
properties of graphene flakes. We find that at near infrared frequencies a
graphene monolayer exhibits a remarkably high third-order optical nonlinearity
which is practically independent of the wavelengths of incident light. The
nonlinear optical response can be utilized for imaging purposes, with image
contrasts of graphene which are orders of magnitude higher than those obtained
using linear microscopy.Comment: 4 pages, 5 figure
Finite element analysis applied to redesign of submerged entry nozzles for steelmaking
The production of steel by continuous casting is facilitated by the use of refractory hollow-ware components. A critical component in this process is the submerged entry nozzle (SEN). The normal operating conditions of the SEN are arduous, involving large temperature gradients and exposure to mechanical forces arising from the flow of molten steel; experimental development of the components is challenging in so hazardous an environment. The effects of the thermal stress conditions in relation to a well-tried design were therefore simulated using a finite element analysis approach. It was concluded from analyses that failures of the type being experienced are caused by the large temperature gradient within the nozzle. The analyses pointed towards a supported shoulder area of the nozzle being most vulnerable to failure and practical in-service experience confirmed this. As a direct consequence of the investigation, design modifications, incorporating changes to both the internal geometry and to the nature of the intermediate support material, were implemented, thereby substantially reducing the stresses within the Al2O3/graphite ceramic liner. Industrial trials of this modified design established that the component reliability would be significantly improved and the design has now been implemented in series production
Zurek-Kibble domain structures: The Dynamics of Spontaneous Vortex formation in Annular Josephson Tunnel Junctions
Phase transitions executed in a finite time show a domain structure with
defects, that has been argued by Zurek and Kibble to depend in a characteristic
way on the quench rate. In this letter we present an experiment to measure the
Zurek-Kibble scaling exponent sigma. Using symmetric and long Josephson Tunnel
Junctions, for which the predicted index is sigma = 0.25, we find sigma = 0.27
+/- 0.05. Further, there is agreement with the ZK prediction for the overall
normalisation.Comment: To be published in Phys. Rev. Lett
Density of kinks just after a quench in an overdamped system
A quench in an overdamped one dimensional model is studied by
analytical and numerical methods. For an infinite system or a finite system
with free boundary conditions, the density of kinks after the transition is
proportional to the eighth root of the rate of the quench. For a system with
periodic boundary conditions, it is proportional to the fourth root of the
rate. The critical exponent predicted in Zurek scenario is put in question.Comment: 4 pages in RevTex + 1 .ps fil
Reducing the Impact of Weak-lensing Errors on Gravitational-wave Standard Sirens
The mergers of supermassive black hole binaries (SMBHBs) can serve as
standard sirens: the gravitational wave (GW) analog of standard candles. The
upcoming space-borne GW detectors will be able to discover such systems and
estimate their luminosity distances precisely. Unfortunately, weak
gravitational lensing can induce significant errors in the measured distance of
these standard sirens at high redshift, severely limiting their usefulness as
precise distance probes. The uncertainty due to weak lensing can be reduced if
the lensing magnification of the siren can be estimated independently, a
procedure called 'delensing'. With the help of up-to-date numerical
simulations, here we investigate how much the weak-lensing errors can be
reduced using convergence maps reconstructed from shear measurements. We also
evaluate the impact of delensing on cosmological parameter estimation with
bright standard sirens. We find that the weak-lensing errors for sirens at can be reduced by about a factor of two on average, but to achieve this
would require expensive ultra-deep field observations for every siren. Such an
approach is likely to be practical in only limited cases, and the reduction in
the weak-lensing error is therefore likely to be insufficient to significantly
improve the cosmological parameter estimation. We conclude that performing
delensing corrections is unlikely to be worthwhile, in contrast to the more
positive expectations presented in previous studies. For delensing to become
more practicable and useful in the future will require significant improvements
in the resolution/depth of the weak-lensing surveys themselves and/or the
accuracy of the methods to reconstruct convergence maps from these surveys.Comment: 19 pages, 22 figures, preparing for submitting to MNRA
Formation of Topological Defects with Explicit Symmetry Breaking
We demonstrate a novel mechanism for the formation of topological defects in
a first order phase transition for theories in the presence of small explicit
symmetry breaking terms. We carry out numerical simulations of collisions of
two bubbles in 2+1 dimensions for a field theory where U(1) global symmetry is
spontaneously as well as explicitly broken. In the coalesced region of bubble
walls, field oscillations result in the decay of the coalesced portion in a
large number of defects (e.g. ten vortices and anti-vortices). We discuss the
implications of our results for axionic strings in the early Universe, for
baryon formation in quark-gluon plasma, and for electric or magnetic field.Comment: Latex file, 8 pages, 6 uuencoded postscript figure
The Hubble Diagram of Type Ia Supernovae in Non-Uniform Pressure Universes
We use the redshift-magnitude relation, as derived by D\c{a}browski (1995),
for the two exact non-uniform pressure spherically symmetric Stephani universes
with the observer positioned at the center of symmetry, to test the agreement
of these models with recent observations of high redshift type Ia supernovae
(SNIa), as reported in Perlmutter et al. (1997). By a particular choice of
model parameters, we show that these models give an excellent fit to the
observed redshifts and (corrected) B band apparent magnitudes of the SNIa data,
but for an age of the Universe which is typically about two Gyr greater than in
the corresponding Friedmann model.
Based on a value of and assuming , the P97 data
implies a Friedmann age of at most 13 Gyr and in fact a best-fit (for ) age of only 10 Gyr. Our Stephani models, on the other hand, can give a
good fit to the P97 data with an age of up to 15 Gyr and could, therefore,
significantly alleviate the conflict between recent cosmological and
astrophysical age predictions. The choice of model parameters is quite robust:
one requires only that the non-uniform pressure parameter, , in one of the
models is negative and satisfies |a| \lte 3 km s Mpc. By
allowing slightly larger, negative, values of one may `fine tune' the model
to give an even better fit to the P97 data.Comment: 36 pages, 2 tables, 6 figures, AAS Latex 4.0, vastly revised version,
new title and abstract, to appear in Ap
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