Current Issue : October - December Volume : 2020 Issue Number : 4 Articles : 5 Articles
Developing a reliable weather forecasting model is a complicated task, as it\nrequires heavy IT resources as well as heavy investments beyond the financial\ncapabilities of most countries. In Lebanon, the prediction model used by the\ncivil aviation weather service at Rafic Hariri International Airport in Beirut\n(BRHIA) is the ARPEGE model, (0.5) developed by the weather service in\nFrance. Unfortunately, forecasts provided by ARPEGE have been erroneous\nand biased by several factors such as the chaotic character of the physical\nmodeling equations of some atmospheric phenomena (advection, convection,\netc.) and the nature of the Lebanese topography. In this paper, we proposed\nthe time series method ARIMA (Auto Regressive Integrated Moving Average)\nto forecast the minimum daily temperature and compared its result with\nARPEGE. As a result, ARIMA method shows better mean accuracy (91%)\nover the numerical model ARPEGE (68%), for the prediction of five days in\nJanuary 2017. Moreover, back to five months ago, in order to validate the accuracy\nof the proposed model, a simulation has been applied on the first five\ndays of August 2016. Results have shown that the time series ARIMA method\nhas offered better mean accuracy (98%) over the numerical model ARPEGE\n(89%) for the prediction of five days of August 2016. This paper discusses a\nmultiprocessing approach applied to ARIMA in order to enhance the efficiency\nof ARIMA in terms of complexity and resources....
Based on classical circuit theory, this article develops a general analytic solution\nof the telegrapherâ??s equations, in which the length of the cable is explicitly\ncontained as a freely adjustable parameter. For this reason, the solution\nis also applicable to electrically short cables. Such a model has become indispensable\nbecause a few months ago, it was experimentally shown that voltage\nfluctuations in ordinary but electrically short copper lines move at signal velocities\nthat are significantly higher than the speed of light in a vacuum. This\nfinding contradicts the statements of the special theory of relativity but not, as\nis shown here, the fundamental principles of electrical engineering. Based on\nthe general transfer function of a transmission line, the article shows mathematically\nthat an unterminated, electrically short cable has the characteristics\nof an ideal delay element, meaning that an input signal appears at the output\nwith a slight delay but remains otherwise unchanged. Even for conventional\ncables, the time constants can be so small that the corresponding signal velocities\ncan significantly exceed the speed of light in a vacuum. The article also\nanalyses the technical means with which this effect can be conveyed to very\nlong cables....
We obtain an approximate value of the quantized momentum eigenvalues,\nn P , together with the space-like coherent eigenvectors for the space-like\ncounterpart of the Schrodinger equation, the Feinberg-Horodecki equation,\nwith a screened Kratzer-Hellmann potential which is constructed by the\ntemporal counterpart of the spatial form of this potential. In addition, we got\nexact eigenvalues of the momentum and the eigenstates by solving Feinberg-\nHorodecki equation with Kratzer potential. The present work is illustrated\nwith three special cases of the screened Kratzer-Hellman potential: the\ntime-dependent screened Kratzer potential, time-dependent Hellmann potential\nand, the time-dependent screened Coulomb potential....
Neutron stars are created due to the cataclysmic merger of two superdense\nstellar corpses. It is now evident that neutron-star smash-ups are the source\nof much of the universeâ??s gold platinum, uranium and other heavy elements.\nHeavy elements contain large neutron excess and thus, neutron energy pairing\nwill play a very important role in the creation of such heavy element. Using\ntheoretical considerations and the results of experimental observations,\nsome important properties of neutron stars such as radius (R), the speed of\nsound inside the neutron star (Cs), the surface speed (Vs) and the most stable\nisotopes in the neutron star have been determined. The calculated values are\ncompared with the values known so far....
The nature of gravitation and G is not well understood. A new gravitation\nmechanism is proposed that explains the origin and essence of the gravitational\nconstant, G. Based on general relativity, the vacuum is considered to be\na superfluid with measurable density. Rotating bodies drag vacuum and create\na vortex with gradient pressure. The drag force of vacuum fluid flow in\nthe arm of the vortex is calculated relative to the static vacuum and a value\nthat is numerically equal to that of G is obtained. Using Archimedesâ?? principle,\nit is determined that G is the volume of vacuum displaced by a force\nequivalent to its weight which is equal to the drag force of the vacuum. It is\nconcluded that the gravitational constant G expresses the force needed to displace\na cubic metre of vacuum that weighs one kg in one second. Therefore,\nG is not a fundamental physical constant but rather is an expression of the resistance\nencountered by the gravitational force in the vacuum....
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