11,114 research outputs found
Closed-loop approach to thermodynamics
We present the closed loop approach to linear nonequilibrium thermodynamics
considering a generic heat engine dissipatively connected to two temperature
baths. The system is usually quite generally characterized by two parameters:
the output power and the conversion efficiency , to which we add a
third one, the working frequency . We establish that a detailed
understanding of the effects of the dissipative coupling on the energy
conversion process, necessitates the knowledge of only two quantities: the
system's feedback factor and its open-loop gain , the product of
which, , characterizes the interplay between the efficiency, the
output power and the operating rate of the system. By placing thermodynamics
analysis on a higher level of abstraction, the feedback loop approach provides
a versatile and economical, hence a very efficient, tool for the study of
\emph{any} conversion engine operation for which a feedback factor may be
defined
Relativistic Effects in Nuclear Matter and Nuclei
The status of relativistic nuclear many-body calculations of nuclear systems
to be built up in terms of protons and neutrons is reviewed. In detail,
relativistic effects on several aspects of nuclear matter such as the effective
mass, saturation mechanism, and the symmetry energy are considered. This review
will especially focus on isospin asymmetric issues, since these aspects are of
high interest in astrophysical and nuclear structure studies. Furthermore, from
the experimental side these aspects are experiencing an additional boost from a
new generation of radioactive beam facilities, e.g. the future GSI facility
FAIR in Germany or SPIRAL2 at GANIL/France. Finally, the prospects of studying
finite nuclei in microscopic calculations which are based on realistic
interactions by including relativistic effects in calculations of low momentum
interactions are discussed.Comment: 57 pages, 16 figure
A Cultural Resources Survey for the Donna Independent School District’s Aquatic Center and Walking Trail Project, Donna, Hidalgo County, Texas
In late April, 2015, Archaeology Consultants, Inc., performed a cultural resources survey for the Donna Independent School District Aquatic Center and Walking Trail Project in Hidalgo County, Texas. About 6.65 acres was surveyed. The location of the project area within public school district property and within a region known to contain numerous archeological sites prompted the Texas Historical Commission to recommend the survey for compliance with the Antiquities Code of Texas. The Commission issued Texas Antiquities Permit 7163 for the survey.
The survey included a search of the Commission’s Texas Archeological Sites Atlas for previous surveys and recorded archaeological sites in the vicinity, pedestrian surface examination, survey-level subsurface testing, and reporting. The background search revealed that apparently no archaeological resources were previously found or recorded within or adjacent to the project area. No cultural evidence, as defined in the Antiquities Code of Texas, was found during the survey, and nothing was collected or curated.
The investigating archaeologists believed that the project as planned should not affect any cultural resources worthy of listing in the National Register of Historic Places or designation as State Antiquities Landmarks or Recorded Texas Historic Landmarks. Therefore Archaeology Consultants, Inc., recommended to the project sponsors and consultants, and to the Commission, that the project should proceed without further work for Antiquities Code of Texas compliance, except in the event of finds of cultural evidence during construction. It was further recommended that if any cultural evidence was found during project-related disturbances, per applicable antiquities statutes and regulations work should immediately be halted in the vicinity until such finds were examined and evaluated by Archaeology Consultants, Inc., by another qualified archaeological consultant, or by the Commission’s Archeology Division staff
Cosmological Density Perturbations with a Scale-Dependent Newton's G
We explore possible cosmological consequences of a running Newton's constant
, as suggested by the non-trivial ultraviolet fixed point
scenario in the quantum field-theoretic treatment of Einstein gravity with a
cosmological constant term. In particular we focus here on what possible
effects the scale-dependent coupling might have on large scale cosmological
density perturbations. Starting from a set of manifestly covariant effective
field equations derived earlier, we systematically develop the linear theory of
density perturbations for a non-relativistic, pressure-less fluid. The result
is a modified equation for the matter density contrast, which can be solved and
thus provides an estimate for the growth index parameter in the
presence of a running . We complete our analysis by comparing the fully
relativistic treatment with the corresponding results for the non-relativistic
(Newtonian) case, the latter also with a weakly scale dependent .Comment: 54 pages, 4 figure
Signal processing in local neuronal circuits based on activity-dependent noise and competition
We study the characteristics of weak signal detection by a recurrent neuronal
network with plastic synaptic coupling. It is shown that in the presence of an
asynchronous component in synaptic transmission, the network acquires
selectivity with respect to the frequency of weak periodic stimuli. For
non-periodic frequency-modulated stimuli, the response is quantified by the
mutual information between input (signal) and output (network's activity), and
is optimized by synaptic depression. Introducing correlations in signal
structure resulted in the decrease of input-output mutual information. Our
results suggest that in neural systems with plastic connectivity, information
is not merely carried passively by the signal; rather, the information content
of the signal itself might determine the mode of its processing by a local
neuronal circuit.Comment: 15 pages, 4 pages, in press for "Chaos
Quantum computation with trapped ions in an optical cavity
Two-qubit logical gates are proposed on the basis of two atoms trapped in a
cavity setup. Losses in the interaction by spontaneous transitions are
efficiently suppressed by employing adiabatic transitions and the Zeno effect.
Dynamical and geometrical conditional phase gates are suggested. This method
provides fidelity and a success rate of its gates very close to unity. Hence,
it is suitable for performing quantum computation.Comment: 4 pages, 5 figures, REVTEX, second part modified, typos correcte
Irradiance calibration with solar diffuser
The sun's energy is used in combination of movable and fixed diffuser plates, windows and apertures which are positioned in a series of test sequences (modes) for reflectance monitoring and calibration without the use of man-made sources. There are three embodiments, or implementations, of the invention--one embodiment uses two diffusers--a working diffuser and a secondary diffuser--the second embodiment uses three diffusers, a working diffuser, a secondary diffuser and a reference diffuser--and the third embodiment uses two diffusers--a working diffuser and a secondary diffuser, the latter also functioning as a cover for the working diffuser. The movable diffusers are mounted on rotatable cones and, in all embodiments, the sun is blocked from reaching the diffusers when not in use. Thus, the sun is used as a stable source for calibration and monitoring and the sun/diffuser combination is used in such a way that the response of all elements of the optical subsystem of the TOMS can be unambiguously and efficiently characterized with high accuracy and precision
Use of ERTS-1 data in identification, classification, and mapping of salt-affected soils in California
There are no author-identified significant results in this report
Monotonic properties of the shift and penetration factors
We study derivatives of the shift and penetration factors of collision theory
with respect to energy, angular momentum, and charge. Definitive results for
the signs of these derivatives are found for the repulsive Coulomb case. In
particular, we find that the derivative of the shift factor with respect to
energy is positive for the repulsive Coulomb case, a long anticipated but
heretofore unproven result. These results are closely connected to the
properties of the sum of squares of the regular and irregular Coulomb
functions; we also present investigations of this quantity.Comment: 13 pages, 1 figur
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