1,249 research outputs found
Probing Quantized Einstein-Rosen Waves with Massless Scalar Matter
The purpose of this paper is to discuss in detail the use of scalar matter
coupled to linearly polarized Einstein-Rosen waves as a probe to study quantum
gravity in the restricted setting provided by this symmetry reduction of
general relativity. We will obtain the relevant Hamiltonian and quantize it
with the techniques already used for the purely gravitational case. Finally we
will discuss the use of particle-like modes of the quantized fields to
operationally explore some of the features of quantum gravity within this
framework. Specifically we will study two-point functions, the Newton-Wigner
propagator, and radial wave functions for one-particle states.Comment: Accepted for publication in Physical Review
Проект парогазовой ТЭЦ с противодавленческими турбинами
Дипломный проект 86страниц, 5рисунков, 10таблиц, 10 источников, 1 приложение, 7 листов графического материала,
ТЕПЛОВАЯ СХЕМА, ПАРОГАЗОВАЯ УСТАНОВКА, КОТЕЛ-УТИЛИЗАТОР, ПАРОВАЯ ТУРБИНА СХЕМА КИП и А.
Объектом исследования является парогазовый энергоблок.
Цель работы – проект парогазового энергоблока.
В процессе работы выполнен расчет тепловой схемы расчетный для проектирования отопления режим.
режим, проектирование котла-утилизатора, технико-экономические расчеты.
В результате выполнения работы показаны преимущества парогазового
энергоблока на базе высокотемпературной газотурбинной установки SGT-800, проект позволяет повысить КПД энергоблока в сравнении с традиционными паросиловыми установками.
Технико-экономические расчеты показали быструю окупаемость проекта и низкую себестоимость электроэнергии.
Пояснительная записка выполнена в текстовом редакторе Microsoft Of-
fice Word 2007, чертежи в графических редакторах Компас.Graduation project 86stranits, 5risunkov, 10tablits 10 sources 1 annex, 7 sheets of graphic material,
Thermal circuit, combined cycle gas turbine, heat recovery boiler, steam turbine and instrumentation A. SCHEME
The object of the research is combined-cycle unit.
Objective - combined cycle power project.
In the process, calculated the thermal circuit current mode for heating design.
mode, design recovery boiler, technical and economic calculations.
As a result of the work shows the benefits of combined cycle gas turbine
power on the basis of high-temperature gas turbine SGT-800 installation, the project improves the power efficiency compared to conventional steam power plants.
Technical and economic calculations have shown a rapid return on the project and the low cost of electricity.
The explanatory note is made in the text editor Microsoft Of-
fice Word 2007 drawing in the graphic editors Compass
A time-space varying speed of light and the Hubble Law in static Universe
We consider a hypothetical possibility of the variability of light velocity
with time and position in space which is derived from two natural postulates.
For the consistent consideration of such variability we generalize
translational transformations of the Theory of Relativity. The formulae of
transformations between two rest observers within one inertial system are
obtained. It is shown that equality of velocities of two particles is as
relative a statement as simultaneity of two events is. We obtain the expression
for the redshift of radiation of a rest source which formally reproduces the
Hubble Law. Possible experimental implications of the theory are discussed.Comment: 7 page
Fine-structure constant variability, equivalence principle and cosmology
It has been widely believed that variability of the fine-structure constant
alpha would imply detectable violations of the weak equivalence principle. This
belief is not justified in general. It is put to rest here in the context of
the general framework for alpha variability [J. D. Bekenstein, Phys. Rev. D 25,
1527 (1982)] in which the exponent of a scalar field plays the role of the
permittivity and inverse permeability of the vacuum. The coupling of particles
to the scalar field is necessarily such that the anomalous force acting on a
charged particle by virtue of its mass's dependence on the scalar field is
cancelled by terms modifying the usual Coulomb force. As a consequence a
particle's acceleration in external fields depends only on its charge to mass
ratio, in accordance with the principle. And the center of mass acceleration of
a composite object can be proved to be independent of the object's internal
constitution, as the weak equivalence principle requires. Likewise the widely
employed assumption that the Coulomb energy of matter is the principal source
of the scalar field proves wrong; Coulomb energy effectively cancels out in the
continuum description of the scalar field's dynamics. This cancellation
resolves a cosmological conundrum: with Coulomb energy as source of the scalar
field, the framework would predict a decrease of alpha with cosmological
expansion, whereas an increase is claimed to be observed. Because of the said
cancellation, magnetic energy of cosmological baryonic matter is the main
source of the scalar field. Consequently the expansion is accompanied by an
increase in alpha; for reasonable values of the framework's sole parameter,
this occurs at a rate consistent with the observers' claims.Comment: RevTeX-4, 22 pages, no figures, added a section on caveats as well as
several new references with discussion of them in body. To appear in Phys.
Rev.
Predicting Urban Heat Island Mitigation with Random Forest Regression in Belgian Cities
peer reviewedAn abundance of impervious surfaces like building roofs in densely populated cities make green roofs a suitable solution for urban heat island (UHI) mitigation. Therefore, we employ random forest (RF) regression to predict the impact of green roofs on the surface UHI (SUHI) in Liege, Belgium. While there have been several studies identifying the impact of green roofs on UHI, fewer studies utilize a remote-sensing-based approach to measure impact on Land Surface Temperatures (LST) that are used to estimate SUHI. Moreover, the RF algorithm, can provide useful insights. In this study, we use LST obtained from Landsat-8 imagery and relate it to 2D and 3D morphological parameters that influence LST and UHI effects. Additionally, we utilise parameters that influence wind (e.g., frontal area index). We simulate the green roofs by assigning suitable values of normalised difference-vegetation index and built-up index to the buildings with flat roofs. Results suggest that green roofs decrease the average LST
Evidence for Host Genome Involvement in Cytokinin Metabolism by Male and Female Cells of Mercurialis annua
Integrin-mediated Cell Attachment Induces a PAK4-dependent Feedback Loop Regulating Cell Adhesion through Modified Integrin αvβ5 Clustering and Turnover
This article presents a novel mechanism deployed by cells to tune cell adhesion levels through the autoinhibitory regulation of integrin adhesion involving the activation of PAK4
Renormalization: the observable-state model
The usual mathematical formalism of quantum field theory is non-rigorous
because it contains divergences that can only be renormalized by non-rigorous
mathematical methods. The purpose of this paper is to present a method of
subtraction of this divergences using the formalism of decoherence. This is
achieved by replacing the standard renormalization method by a projector on a
well defined Hilbert subspace. In this way a list of problems of the standard
formalism disappears while the physical results of QFT remains valid. From it
own nature, this formalism can be used in non-renormalizable theories.Comment: 23 page
On the nature of continuous physical quantities in classical and quantum mechanics
Within the traditional Hilbert space formalism of quantum mechanics, it is
not possible to describe a particle as possessing, simultaneously, a sharp
position value and a sharp momentum value. Is it possible, though, to describe
a particle as possessing just a sharp position value (or just a sharp momentum
value)? Some, such as Teller (Journal of Philosophy, 1979), have thought that
the answer to this question is No -- that the status of individual continuous
quantities is very different in quantum mechanics than in classical mechanics.
On the contrary, I shall show that the same subtle issues arise with respect to
continuous quantities in classical and quantum mechanics; and that it is, after
all, possible to describe a particle as possessing a sharp position value
without altering the standard formalism of quantum mechanics.Comment: 26 pages, LaTe
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