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Space Science International [141 followers] Follow Open Access journal ISSN (Print) 1948-9927 - ISSN (Online) 1948-9935 Published by Science Publications [31 journals] |
- An Integrated Approach to Modelling of Flood Hazards in the Rapidly
Growing City of Osogbo, Osun State, Nigeria
Abstract: In recent times, the swift and uncoordinated urban expansion in the medium sized city of Osogbo has increasingly encroached on the environmental sensitive areas. This uncoordinated exploitation of the ecological fragile areas for urban development has triggered urban flooding, which poses serious threat to human lives and properties in the city. This study therefore utilized geospatial technologies to generate flood hazard model for medium sized cities in developing countries in general and Nigeria in particular with a view to identifying hotspots and providing measures to forestall flood occurrences. The study used Shuttle Radar Topography Mission-Digital Elevation Model (SRTM-DEM), Landsat 7- 2000 and Operational Land Imager 8 (OLI)- 2015 images. Multi-criteria evaluation method was used to derive the physical characteristics of watersheds from the data to delineate the areas vulnerable to flooding. Flood inundation characteristics were simulated using Hydrologic Engineering Centre-River Analysis System (HEC-RAS) model with GIS interface and found discharge of over 500 m3/s for the 100-year profile period to be high, given the size of the analyzed basin (207.41 km2). The flood hazard map showed that 3.92, 103.38 and 100.11 km2 were least, moderately and highly vulnerable areas respectively. Most prone areas were built-ups with high impervious surface in the basin area where floodplain traversed high and moderate vulnerability zones. The study advocates consistent use of dynamic model within GIS for floodplain delineation and management planning to reduce the flood hazards.
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- The Cosmic Microwave Background: A Condition of Maximum
Abstract: It is shown that by imposing a condition of maximum value for the luminosity of the source at the origin of the cosmic microwave background, one arrives at a set of equations characteristic to important cosmological quantities. Although these equations do not have a solid theoretical support, the values of the parameters derived from them agree surprisingly well with the values given by the most recent measurements.
- On the Generation of Equivalent ‘Black Hole’ Metrics:
A Review
Abstract: Various line-elements purporting different types of blackhole universes have been advanced by cosmologists but a means by which therequired infinite set of equivalent metrics can be generated has evaded them.Without such a means the theory of black holes is not only incomplete but alsoill-posed. Notwithstanding, the mathematical form by which the infinite set ofequivalent metrics is generated was first revealed in 2005, from other quartersand it has in turn revealed significant properties of black hole universeswhich cosmology has not realised. The general metric ground-form from which theinfinite set of equivalent ‘black hole’ metrics can be generated is presentedherein and its consequences explored.
- Multi-Timescale Microscopic Theory for Radiation Degradation of Electronic
and Optoelectronic Devices
Abstract: A multi-timescale hybrid model is proposed to studymicroscopically the degraded performance of electronic devices, covering threeindividual stages of radiation effects studies, including ultra-fastdisplacement cascade, intermediate defect stabilization and cluster formation,as well as slow defect reaction and migration. Realistic interatomic potentialsare employed in molecular-dynamics calculations for the first two stages up to100 ns as well as for the system composed of layers with thicknesses ofhundreds of times the lattice constant. These quasi-steady-state results for individuallayers are input into a rate-diffusion theory as initial conditions tocalculate the steady-state distribution of point defects in a mesoscopic-scalelayered-structure system, including planar biased dislocation loops andspherical neutral voids, on a much longer time scale. Assisted by thedensity-functional theory for specifying electronic properties of pointdefects, the resulting spatial distributions of these defects and clusters aretaken into account in studying thedegradation of electronic and optoelectronic devices, e.g., carriermomentum-relaxation time, defect-mediated non-radiative recombination,defect-assisted tunneling of electrons and defect or charged-defect Ramanscattering as well. Such theoretical studies are expected to be crucial infully understanding the physical mechanism for identifying defect species,performance degradations in field-effect transistors, photo-detectors,light-emitting diodes and solar cells and in the development of effectivemitigation methods during their microscopic structure design stages.
- THREE FUNDAMENTAL MASSES DERIVED BY DIMENSIONAL ANALYSIS
Abstract: Three new mass dimension quantities have been derived by dimensional analysis, in addition to the famous Planck mass mP ~10-8 kg. These masses have been derived by means of fundamental constants-the speed of light (c), the gravitational constant (G), the Plank constant (?) and the Hubble constant (H). The enormous mass m1 ~1053 kg practically coincides with the Hoyle-Carvalho formula for the mass of the observable universe. The extremely small mass m2 ~10-33 eV has been identified with the minimum quantum of energy, which seems close to the graviton mass. It is noteworthy that the Planck mass appears geometric mean of the masses m1 and m2. The mass m3 ~107 GeV could not be unambiguously identified at present time. Besides, the order of magnitude of the total density of the universe has been estimated by this approach.
- EARLY GREEK ASTROPHYSICS: THE FOUNDATIONS OF MODERN SCIENCE AND TECHNOLOGY
Abstract: The foundations of modern science and technology, metrology, experimental physics, theoretical physics, theoretical mathematics, astrophysics, including applied optics and spectroscopy go back to the Prehistoric, Presocratic, Classical and Hellenistic Greece. This tradition is well deep rooted in time, going back mainly to the epoch of the prehistoric Aegean sea, the mainland of Greece and the Islands, Cycladic, Euboea, as well as Crete, at the late Neolithic period, probably starting back at 4400 BC. Humans observe the sky before the prehistoric era and wonder and as even Plato declares, these observations that lead us to try and understand the Cosmos make us humans as well, since the actual meaning and etymology of this term human in Greek, the word ANTHROPOS, is the one that looks up, observes the ordered Universe and tries to understand its nature and its hidden Laws which govern it. Science and Philosophy emerged as a result of the human efforts to live even more successfully within a hostile environment. Humanity eventually manages to understand Nature and especially the Cosmos, using the Pythagorean principle: “Nature can only be understood accurately by the use of Mathematics, which expresses the underlying Laws of Nature and which explain all natural phenomena based on the Principe of Causality.
- SPACE TIME COVARIANCE OF CANONICAL QUANTIZATION OF GRAVITY: A (FORMAL)
GENERAL RESULT AND THE (RIGOROUS) EXPLICIT CASE OF 2+1 QUANTUM COSMOLOGY
Abstract: A general classical theorem is presented according to which all invariant relations among the space time metric scalars, when turned into functions on the Phase Space of full Pure Gravity (using the Canonical Equations of motion), be-come weakly vanishing functions of the Quadratic and Linear Constraints. The implication of this result is that (formal) Dirac consistency of the Quantum Operator Constraints (annihilating the wave Function) suffices to guarantee space time covariance of the ensuing quantum theory: An ordering for each invariant relation will always exist such that the emanating operator has an eigenvalue identical to the classical value. The example of 2+1 Quantum Cosmology is explicitly considered: The four possible “Cosmological Solutions” -two for pure Einstein's equations plus two more when a ? term is present- are exhibited and the corresponding models are quantized. The invariant relations describing the geometries are explicitly calculated and promoted to operators whose eigenvalues are their corresponding classical values.
- NILPOTENCE AND THE GENERALIZED UNCERTAINTY PRINCIPLE (S)
Abstract: We point out that some of the proposed generalized/modified uncertainty principles originate from solvable, or nilpotent at appropriate limits, “deformations” of Lie algebras. We briefly comment on formal aspects related to the well-posedness of one of these algebras. We point out a potential relation of such algebras with Classical Mechanics in the spirit of the symplectic non-squeezing theorem. We also point out their relation to a hierarchy of generalized measure theories emerging in a covariant formalism of quantum gravity.
- DISCOVERY OF DYNAMICAL 3-SPACE: THEORY, EXPERIMENTS AND OBSERVATIONS-A
REVIEW
Abstract: The existence of space as a dynamical system was recently revealed in 2002, following the discovery that the Michelson-Morley light speed anisotropy experiment of 1887 was not null. Numerous later experiments have confirmed that discovery, as reviewed here, with the latest being the discovery of a very simple and cheap nanotechnology quantum detector method for observing space and its fluctuations/turbulence: Gravitational waves. As well over the last ten years the dynamical theory for space has been under development and has now been successfully tested against experiment and astronomical observations, explaining, in particular, the observed characteristics of galactic black holes, galactic rotations and universe expansion, all without “dark matter” and “dark energy”.
- NON-SINGULAR THERMODYNAMIC GRAVITY
Abstract: Newton formed his laws of motion, but still had to assume a law of gravity in order to determine the motions of bodies interacting through gravitational forces. Newton gave a prescription of how to find the dynamics produced by gravity. Einstein sought to determine the motions of gravity without using a force. Rather, he sought a system of equations by which the dynamics of bodies interacting through gravity were determined by the least distance between two points in a curved space. In both of these approaches gravity was basically independent of other forces of nature. Newton’s approach was to provide a system of equations that determined the motion of bodies interacting through forces in any choice of geometry. Einstein’s approach was to require that the force of gravity determine the geometry since he sought to find the motions without using a force. Newton gave three laws of motion in equations that could be used to find various types of energy such as potential energy or kinetic energy. This arrangement has the forces determining the energy of interactions. The approach presented here basically reverses these roles of energy and forces. It starts with a law stating the conservation of energy which states how any exchange of energy between a system and its surroundings affects the system’s energy and the work it can perform. It is a law stating how these three energies, exchange energy, system energy and work, can interact. The expression for work, force acting through a distance, must be a path dependent term which also makes the exchange energy path dependent. However, the system’s energy is not path dependent. The difference between the path dependence of the work and the path independence of the system’s energy is shown to be crucial to the law’s determination of dynamics.
- TUNNELING OF DIRAC PARTICLES FROM PHANTOM REISSNER NORDSTROM ANTI DE
SITTER BLACK HOLE
Abstract: We study the Hawking radiation of Dirac particles from RN ADS black hole through tunneling method. We use charge relativistic Dirac equation to study the emission of such particles. To solve Dirac equation we use WKB approximation and find the tunneling probability of outgoing particles. Finally we find the Hawking temperature for such type of black holes.
- COSMOLOGICAL DATA COULD HAVE A MICROSCOPIC, NOT MACROSCOPIC, CAUSE
Abstract: A slight continuous increase of the rest masses and the electric charges of material particles can justify quantum phenomena and the cosmological data. This increase can only Î¿ccur in a strictly defined way: the law of selfvariations. The law of selfvariations condenses into one equation the totality of the cosmological data, as we observe them from the time of Hubble up to the present. The consequences of the selfvariations are recorded persistently and in the most immediate way in the cosmological data. The observation of the redshift of distant astronomical objects by Hubble in the beginning of the last century, leads to only one certain conclusion: one or more physical quantities, which we would expect to be constant in the Universe, in reality vary. The physical theories of the twentieth century justify the redshift macroscopically, via the expansion of the Universe. But the redshift can also be justified differently, with microscopic causes that predict a self-consistent cosmological model in accordance with all of the cosmological data. The problems caused by modern observations to the Standard Cosmological Model, are exactly focused at the points where the two models make different predictions. We propose a revaluation of the cosmological data, based on the law of the selfvariations.
- ASYMPTOTIC GIANT BRANCH STARS MIGRATION FROM THE CENTRAL OF THE MILKY WAY
GALAXY TO OUR SUNĂ¢€™S BIRTHPLACE AND ITS RELATION WITH SILICON
CARBIDE GRAINS
Abstract: Silicon carbide grains found in meteorites are peculiar in their age and isotopic ratios; they formed before the Sun was born and their isotopic signature indicates that they come from a different galactic region. This study aims to seek a possible paradigm for such richness and peculiarity through Monte Carlo simulation of scattering of Asymptotic Giant Branch (AGB) stars off molecular cloud. Such approach randomly generates AGB stars in regions close to the Galaxy bulge and examines possibility of migration to outer regions by scattering off molecular cloud. A successful explanation to this problem will influence how we think nuclides were formed and then distributed in the Galaxy and will shed new light unto the age and the chemical evolution of the Milky Way Galaxy. Thus, it is important that we know where do they come from and how do they end up in our backyard?
- THE COSMIC MICROWAVE BACKGROUND: A STRANGE CHARACTERISTIC
Abstract: The ratio of the self-gravitational energy density of the scattering particles in the universe to the energy density of the scattered photons in the Cosmic Microwave Background (CMB) is the same in any volume of space. These two energy densities are equal at a radiation temperature on the order of the present CMB temperature.
- TRANSFORMITY: THE DEPENDENCE OF THE LAWS OF PHYSICS ON HIGHER-DIMENSIONAL
COORDINATE TRANSFORMATIONS
Abstract: In unified field theories with more than four dimensions, the form of the equations of physics in spacetime depends in general on the choice of coordinates in higher dimensions. The reason is that the group of coordinate transformations in (say) five dimensions is broader than in spacetime. This kind of gauge dependence is illustrated by two examples: a cosmological model in general relativity and a matter wave in quantum theory. Surprisingly, both are equivalent by coordinate transformations to flat featureless five-dimensional space. This kind of transformity is of fundamental significance for the philosophy of physics.
- THE LENSE-THIRRING EFFECT IN THE ANOMALISTIC PERIOD OF CELESTIAL BODIES
Abstract: In the weak field and slow motion approximation, the general relativistic field equations are linearized, resembling those of the electromagnetic theory. In a way analogous to that of a moving charge generating a magnetic field, a mass-energy current can produce a gravitomagnetic field. In this contribution, the motion of a secondary celestial body is studied under the influence of the gravitomagnetic force generated by a spherical primary. More specifically, two equations are derived to approximate the periastron time rate of change and its total variation over one revolution (i.e., the difference between the anomalistic period and the Keplerian period). Kinematically, this influence results to an apsidal motion. The aforementioned quantities are numerically estimated for Mercury, the companion star of the pulsar PSR 1913+16, the companion planet of the star HD 80606 and the artificial Earth satellite GRACE-A. The case of the artificial Earth satellite GRACE-A is also considered, but the results present a low degree of reliability from a practical standpoint.
- A BRIEF TOUR INTO THE HISTORY OF GRAVITY: FROM DEMOCRITUS TO EINSTEIN
Abstract: The History of Gravity encompasses many different versions of the idea of the Gravitational interaction, which starts already from the Presocratic Atomists, continues to the doctrines of the Platonic and Neoplatonic School and of the Aristotelian School, passes through the works of John Philoponus and John Bouridan and reaches the visions of Johannes Kepler and Galileo Galilei. Then, the major breakthrough in the Theory of Motion and the Theory of Gravity takes place within the realm of Isaac Newtonâ€™s most famous Principia and of the work of Gottfried Leibniz, continues with the contributions of the Post-newtonians, such as Leonhard Euler, reaches the epoch of its modern formulation by Ernst Mach and other Giants of Physics and Philosophy of this epoch, enriches its structure within the work of Henry Poincare and finally culminates within the work of Albert Einstein, with the formulation of the Theory of Special Relativity and of General Relativity at the begin of the 20th century. The evolution of the Theory of General Relativity still continues up to our times, is rich in forms it takes and full of ideas of theoretical strength. Many fundamental concepts of the Epistemology and the History of Physics appear in the study of the Theory of Gravity, such as the notions of Space, of Time, of Motion, of Mass, in its Inertial, Active Gravitational and Passive Gravitational form, of the Inertial system of reference, of the Force, of the Field, of the Riemannian Geometry and of the Field Equations. These primary fundamental theoretical and structural notions appearing each time in the corresponding Theories of Gravity and within the various Paradigms of the Gravitational interaction. We shall refer briefly to the History of Gravity, mentioning only a few landmarks or great personalities which shaped these fundamental physical and epistemological notions.
- QUANTUM STANDPOINT FOR A MORE UNDERSTANDABLE UNIVERSE
Abstract: The study implements the concept of space-time quantum uncertainty to outline a possible model of universe. Simple considerations show that the relativistic equations inferred as a consequence of the uncertainty allow describing effects typically expected in the frame of quantum phenomena, e.g., the fluctuations. These results contribute to clarify issues today still open, like the dark energy, the inflationary expansion of the universe and the possible existence of antigravity.