Gravity Research Papers - Academia.edu (original) (raw)

In June 2005, a four-man SEAL team was dropped off by he li cop ter in the mountains of eastern Af ghan i stan with the mission to kill an insurgent commander. They were in the rugged, forested terrain of the Hindu Kush near the border with Pakistan, in an area where they had never been before. Soon afterward, these well-trained, fit Americans felt overwhelmed by their exertion in trying to navigate the physical volume of those mountains. The only SEAL to survive the mission, Markus Luttrell, subsequently wrote in his book Lone Survivor that their training for mountain warfare in California had not prepared them for those mountains, where "the terrain was absolutely horrible." The mountain was "so steep" that in their first few hours it was "a goddamned miracle we didn't fall off and break our necks." 1 Tired and eventually discovered by locals, the SEALs were ambushed by combatants who knew the terrain and controlled the most favorable position in mountain warfare: the higher ground. While the four Americans were being fired upon from above, they fled downhill, repeatedly tripping and falling off amid steep slopes. Luttrell describes one of their falls, "a nearly sheer drop," as follows:

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- Posthumanism, Space and Place, Materiality (Anthropology), Phenomenology of Space and Place

The latest advances in bioregenerative strategies for long-term life support in extraterrestrial outposts such as on Mars have indicated soil-based cropping as an effective approach for waste decomposition, carbon sequestration, oxygen production, and water biofiltration as compared to hydroponics and aeroponics cropping. However, it is still unknown if cropping using soil systems could be sustainable in a Martian greenhouse under a gravity of 0.38g. The most challenging aspects are linked to the gravity-induced soil water flow; because water is crucial in driving nutrient and oxygen transport in both liquid and gaseous phases, a gravitational acceleration lower than g = 9.806 m s À2 could lead to suffocation of microorganisms and roots, with concomitant emissions of toxic gases. The effect of Martian gravity on soil processes was investigated using a highly mechanistic model previously tested for terrestrial crops that couples soil hydraulics and nutrient biogeochemistry. Net leaching of NO À 3 solute, gaseous fluxes of NH 3 , CO 2 , N 2 O, NO and N 2 , depth concentrations of O 2 , CO 2 and dissolved organic carbon (DOC), and pH in the root zone were calculated for a bioregenerative cropping unit under gravitational acceleration of Earth and for its homologous on Mars, but under 0.38g. The two cropping units were treated with the same fertilizer type and rate, and with the same irrigation regime, but under different initial soil moisture content. Martian gravity reduced water and solute leaching by about 90% compared to Earth. This higher water holding capacity in soil under Martian gravity led to moisture content and nutrient concentrations that favoured the metabolism of various microbial functional groups, whose density increased by 5-10% on Mars as compared to Earth. Denitrification rates became substantially more important than on Earth and ultimately resulted in 60%, 200% and 1200% higher emissions of NO, N 2 O and N 2 gases, respectively. Similarly, O 2 and DOC were consumed more rapidly in the Martian soil and resulted in about 10% increase in CO 2 emissions. More generally, Martian cropping would require 90% less water for irrigation than on Earth, being therefore favourable for water recycling treatment; in addition, a substantially lower nutrient supply from external sources such as fertilizers would not compromise nutrient delivery to soil microorganisms, but would reduce the large N gas emissions observed in this study.

- by Celine Pallud
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- Mechanical Engineering, Aerospace Engineering, Biogeochemistry, Agriculture
- by Håkan Ahlström
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- Magnetic Resonance Imaging, Evaluation, Image Reconstruction, Gravity

Research on Lasem fault modeling has been carried out to analyze the location of the Lasem fault indication. The Lasem fault is indicated in 3 zones, namely the Rembang zone, Randublatung depression zone and Semarang-Rembang depression zone. Lasem fault is a fault located in the Pati-Rembang area which is an active fault and is close to the Semarang area. This research uses the gravity method as a basic understanding. The data uses obtained through the TOPEX/POSEIDON website. The data obtained were 154 measurement points at coordinates 111000' BT (E)-111013' BT (E) and 6040' LS (S)-6050' LS (S). The results obtained on TOPEX/POSEIDON are data of latitude and longitude coordinates, elevation and free air anomaly correction values. After that, further correction is made in the form of bouguer correction and terrain correction so that the complete bouguer anomaly value is obtained. The complete bouguer anomaly data is analyzed by spectrum with the results of depth estimation for the anomaly. Then an upward continuation is carried out to separate regional anomalies and residual anomalies. After that the gradient analysis filter, eulerdeconvolution, 3D and 2D modeling are done. Gradient analysis filter in the form of first horizontal gradient with the results in the form of fault indications and second vertical derivatives to determine the type of fault that is strike-slip fault. Euler deconvolution is used to determine the estimated subsurface depth with yields of up to 5000 m below sea level. 3D modeling is carried out to see fault indications which result that faults can be seen from depths of 1200 m to 4000 m. 2D modeling results show the types of rocks in the form of claystone, sandstone, limestone, and andesite, respectively the rocks have a density of 2.21 gr/cm 3 , 2.35 gr/cm 3 , 2.55 gr/cm 3 and 2.6 gr/cm 3. Keywords-Lasem fault, gravity method, gradient analysis, euler analysis, 3D and 2D modeling.. I. INTRODUCTION The gravity method is one of the geophysical methods based on the measurement of small variations in a gravity field. The difference in small variations or deviations in the terrain from point to point above the surface of the earth, is caused by lateral variations [1][2]. The gravity method is a method that studies variations in the gravity field that occur by variations in the density of rock masses below the surface, so that the variation investigated is the difference in the gravity field from an observation point to another point [2][3]. The gravity method can be used in analyzing the presence of the lasem fault by looking for the density variable that is below the surface. Lasem Fault is a fault with the longest straightness, occupying a depression with axes trending southwest-northeast. In previous research which concluded that by doing inversion modeling from gravity data concluded that the Lasem fault lies in 3 zones, namely the Rembang zone, the Randublatung depression zone and the Semarang-Rembang depression zone. Then the inversion modeling results obtained are depression models in the south and north of the study area with a density in the range of values 2,1-2,8 gr/cm3 [4].

- by chabib muwaffaq
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- Geology, Gravity, TOPEX, Lasem

It is likely that the holographic principle will be a consequence of the would be theory of quantum gravity. Thus, it is interesting to try to go in the opposite direction: can the holographic principle fix the gravitational interaction? It is shown that the classical gravitational interaction is well inside the set of potentials allowed by the holographic principle. Computations clarify which role such a principle could have in lowering the value of the cosmological constant computed in QFT to the observed one.

- by G. Vilasi
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- Physics, Quantum Gravity, Gravity, Key words

This paper proposes a Modular Universe toy-model (MUTM) predicting all elementary particles (EPs) to be actually quantum black-holes (QBHs) (gravitational quasi-singularities) governed by self-gravity and self-antigravity. This paper continues (from an alternative angle of view) the work of other past articles/preprints of the same author in physics (cited in anti-chronological order, from the latest to the oldest.
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Rep le 18 Avril1985 er sous formefinale le 13 AoPt 1986) RCsum&--Une methode numerique du type Tau-Chebyshev est utilisee pour d&ire ie mouvement dun fluide de Boussinesq en rotation, soumis a un gradient thermique radial. L'analyse des regimes d'tcoulement axisymetriques est developpee pour des cavites annulaires, lorsque les paramttres physiques varient: 0 < Re < 2500 ; Ra = lo', k 104, 10'; 0 < Fr < 25. La transition entre les regimes de convection thermique et ceux domints par la rotation rtsulte de la competition entre les diffirentes forces: gravifique, centrifuge et de Coriohs. La validite des solutions asymptotiques propokes par Hunter (1966) lorsque Fr << 1 et R, >> 1, est disc&e lorsque Re varie.

- by Patrick Bontoux
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- Engineering, Convection, Heat and Mass Transfer, Gravity

The fundamental holographic principle is first proposed, then demonstrated in its validity and viability through a thought experiment and then finally derived. The Heisenberg uncertainty relations are shown to follow from this fundamental relation. The quantum blackhole entropy is then demonstrated using this holographic uncertainty relation along with the application of the Landauer’s principle for the thermodynamic erasure of a bit yielding a formula with a logarithmic correction. The blackhole entropy is found to be half the value normally delivered by any other method. So, it is proposed that there is a real relevant physical horizon at the twice the Schwarzschild radius dubbed the holographic information geometric horizon.

- by Giovanna Sona and +1
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- Gravity, Geoid Determination, Geoid

This is an introductory set of lecture notes on quantum cosmology, given in 1995 to an audience with interests ranging from astronomy to particle physics. Topics covered: 1. Introduction: 1.1 Quantum cosmology and quantum gravity; 1.2 A brief history of quantum cosmology. 2. Hamiltonian formulation of general relativity: 2.1 The 3+1 decomposition; 2.2 The action. 3. Quantisation: 3.1 Superspace; 3.2 Canonical quantisation; 3.3 Path integral quantisation; 3.4 Minisuperspace; 3.5 The WKB approximation; 3.6 Probability measures; 3.7 Minisuperspace for the Friedmann universe with massive scalar field. 4. Boundary Conditions: 4.1 The no-boundary proposal; 4.2 The tunneling proposal. 5. The predictions of quantum cosmology: 5.1 The period of inflation; 5.2 The origin of density perturbations; 5.3 The arrow of time.

- by David L Wiltshire
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- Quantum Gravity, General Relativity, Quantum Cosmology, Gravity

The Vapor Extraction (VAPEX) process, a newly developed Enhanced Oil Recovery (EOR) process to recover heavy oil and bitumen, has been studied theoretically and experimentally and is found a promising EOR method for certain heavy oil... more

- by behzad rostami
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- Petroleum, Enhanced Oil Recovery, Gravity, Permeability

Motivated by the lack of rotating solutions sourced by matter in General Relativity as well as in modified gravity theories, we extend a recently discovered exact rotating solution of the minimal Einstein-scalar theory to its counterpart in Eddington-inspired Born-Infeld gravity coupled to a Born-Infeld scalar field. This is accomplished with the implementation of a well-developed mapping between solutions of Ricci-Based Palatini theories of gravity and General Relativity. The new solution is parametrized by the scalar charge and the Born-Infeld coupling constant apart from the mass and spin of the compact object. Compared to the spacetime prior to the mapping, we find that the high-energy modifications at the Born-Infeld scale are able to suppress but not remove the curvature divergence of the original naked null singularity. Depending on the sign of the Born-Infeld coupling constant, these modifications may even give rise to an additional timelike singularity exterior to the null ...

- by Wei-Hsiang Shao
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- Physics, General Relativity, Black Holes, Singularity

Camera calibration has been studied extensively in computer vision and photogrammetry and the proposed techniques in the literature include those using 3D apparatus (two or three planes orthogonal to each other or a plane undergoing a pure translation, etc.), 2D objects (planar patterns undergoing unknown motions), and 0D features (self-calibration using unknown scene points). Yet, this paper proposes a new calibration technique using 1D objects (points aligned on a line), thus filling the missing dimension in calibration. In particular, we show that camera calibration is not possible with free-moving 1D objects, but can be solved if one point is fixed. A closed-form solution is developed if six or more observations of such a 1D object are made. For higher accuracy, a nonlinear technique based on the maximum likelihood criterion is then used to refine the estimate. Singularities have also been studied. Besides the theoretical aspect, the proposed technique is also important in practice especially when calibrating multiple cameras mounted apart from each other, where the calibration objects are required to be visible simultaneously.

- by Zhengyou Zhang
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- Information Systems, Algorithms, Computer Vision, Photogrammetry

In this work, our prime focus is to study the one to one correspondence between the conduction phenomena in electrical wires with impurity and the scattering events responsible for particle production during stochastic inflation and reheating implemented under a closed quantum mechanical system in early universe cosmology. In this connection, we also present a derivation of quantum corrected version of the Fokker-Planck equation without dissipation and its fourth order corrected analytical solution for the probability distribution profile responsible for studying the dynamical features of the particle creation events in the stochastic inflation and reheating stage of the universe. It is explicitly shown from our computation that quantum corrected Fokker-Planck equation describe the particle creation phenomena better for Dirac delta type of scatterer. In this connection, we additionally discuss Itô, Stratonovich prescription and the explicit role of finite temperature effective potential for solving the probability distribution profile. Furthermore, we extend our discussion of particle production phenomena to describe the quantum description of randomness involved in the dynamics. We also present computation to derive the expression for the measure of the stochastic non-linearity (randomness or chaos) arising in the stochastic inflation and reheating epoch of the universe, often described by Lyapunov Exponent. Apart from that, we quantify the quantum chaos arising in a closed system by a more strong measure, commonly known as Spectral Form Factor using the principles of random matrix theory (RMT). Additionally, we discuss the role of out of time order correlation function (OTOC) to describe quantum chaos in the present non-equilibrium field theoretic setup and its cona e-mails:

- by Sayantan Choudhury
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- Physics, Quantum Physics, Gravitation, Foundations of Quantum Mechanics

Space and Time are continuous absolute quantities. They don't change with anything at all. However, the dimension and duration of an object or event can change with the local gravitational field and aging of the universe. This is because that Wu's Unit Length (diameter) and Wu's Unit Time (period) of Wu's Pairs (building blocks of the universe) in an object or event can be affected by the bombardment of gravitons complying with gravitational field in accordance to Graviton Radiation and Contact Interaction Theory, and also the shrinkage of Wu's Pairs due to aging of the universe in compliance with Cosmic Microwave Background Radiation (CMB). According to Wu's Spacetime Shrinkage Theory and intrinsic atomic and subatomic structures, a linear relationship is proposed between the quantities of the property of a corresponding identical object or event and the gravitational field and aging of the universe. In addition, under Thermodynamic Equilibrium and local Subatomic Equilibrium, three fundamental principles: Principle of Equilibrium, Principle of Parallelism and Principle of Correspondence are derived, such that the correlations of the quantities of the properties between two objects or events at the same location and time (same gravitational field and aging of the universe) can be established. Furthermore, based on Wu's Spacetime Equation t yy = γl yy 3/2 , Wu's Unit Length and Wu's Unit Time of Wu's Pair are correlated to each other. As a result, the correlations of the simple properties such as dimension and duration, or the composite properties such as velocity and acceleration of an object or event, with respect to the gravitational field and aging of the universe, or further to Wu's Unit Length of a reference corresponding identical subatomic particle at the same location and time (same gravitational field and aging of the universe) can be established. This can be used successfully to interpret many important physical phenomena, such as Deflection of Light, Perihelion Precession of Mercury, Cosmological Redshift, Hubble's Law, Einstein's General Relativity, Spacetime and Field Equations.

- by Edward T . H . Wu
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- Theoretical Physics, Gravitation, Relativity, General Relativity

I proposed a new expansion force to explain the flat rotation curves of plane galaxies, in a Newtonian approach in 2016. This force is validated here in General Relativity for an inhomogeneous radially symmetrical universe. It can be deduced from the solution of Einstein's equation with a cosmological constant. A pseudo-Schwarzschild "twin-potential" metric is considered, with two different potentials for the space and time dimensions. The expansion force results as a repulsive dual gravity. Negative masses are needed. The necessary mass repartitions are computed, in connection with the radial dynamics and the expansion rate's evolution. A linear model and a quadratic model are studied, connected with the observation representations of a universe in accelerated expansion. It is a first step towards a better representation of an inhomogeneous universe. The framework can be applied to deduce the universe mass repartition form the measured values of the expansion rate variation. Résumé J'ai proposé en 2016 une nouvelle force d'expansion pour expliquer les courbes de rotation plates des galaxies spirales dans une approche Newtonienne. Cette force est validée ici dans le cadre de la Relativité Générale pour un univers inhomogène à symétrie radiale. On peut la déduire comme solution de l'équation d'Einstein avec Constante Cosmologique. On considère une métrique à « potentiels jumelés », avec deux potentiels différents pour les dimensions spatiales et temporelles. Il en résulte une force d'expansion agissant comme une gravité duale répulsive. Il faut des masses négatives. On calcule les répartitions de masses nécessaires, en liaison avec la dynamique radiale et l'évolution du taux d'expansion. On étudie un modèle linéaire et un modèle quadratique, en lien avec les représentations d'un univers observé en expansion accélérée. Il s'agit là d'une première étape vers une meilleure représentation d'un univers inhomogène. Ce cadre peut être appliqué pour déduire la répartition de masses de l'univers à partir des valeurs mesurées du taux d'expansion.

- by Jacques Fleuret
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- Universe expansion, Gravity, Gravity Model, Solutions of Einstein Field Equations
- by Thierry De Mees
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- Cosmology (Physics), Gravitation, Theoretical astrophysics, Astrophysics

This work presents some updates on the design of the European Asteroid Impact Mission. In particular, the landing trajectory of MASCOT-2 is investigated and analyzed into detail during close-proximity operations at the binary asteroid 65803 Didymos. Design opportunities are investigated using a three-body approach to model the dynamical system in the close proximity of the asteroid couple. Landing requirements, applicable to the mission scenario under study, are presented and a suitable strategy is selected, by conveniently exploiting three-body dynamics. Uncertainties in release and touch down conditions are modeled and successful landing probability is assessed.

- by Fabio Ferrari
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- Asteroids, Gravity, Gravity Model, Space Missions

This paper presents a new environment to simulate close-proximity dynamics around rubble-pile asteroids. The code provides methods for modeling the aster-oid's gravity field and surface through granular dynamics. It implements state-of-the-art techniques to model both gravity and contact interaction between particles: 1) mutual gravity as either direct N2 or Barnes-Hut GPU-parallel octree and 2) contact dynamics with a soft-body (force-based, smooth dynamics), hard-body (constraint-based, non-smooth dynamics), or hybrid (constraint-based with compliance and damping) approach. A very relevant feature of the code is its ability to handle complex-shaped rigid bodies and their full 6D motion. Examples of spacecraft close-proximity scenarios and their numerical simulations are shown.

- by Fabio Ferrari
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- Computer Science, Parallel Computing, Planetary Science, Asteroids

Spherical symmetry in f (R) gravity is discussed in details considering also the relations with the weak field limit. Exact solutions are obtained for constant Ricci curvature scalar and for Ricci scalar depending on the radial coordinate. In particular, we discuss how to obtain results which can be consistently compared with General Relativity giving the well known post-Newtonian and post-Minkowskian limits. Furthermore, we implement a perturbation approach to obtain solutions up to the first order starting from spherically symmetric backgrounds. Exact solutions are given for several classes of f (R) theories in both R = constant and R = R(r).

- by Salvatore Capozziello
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- General Relativity, Gravity, Mathematical Sciences, Curvature

We will define the mass of an electron in the context of Weinberg's empirical formula that relates the mass of a pion to fundamental physical constants, namely the gravitational and Planck constants, the speed of light in vacuum and the Hubble constant. After redefining the Weinberg formula to apply for electrons instead of pions we will add density parameters, used in modern Cosmology, to the Hubble constant in an attempt to persevere the universality of free fall which is one of the corner stones of General Relativity. Universality of free fall is not violated if fundamental physical constants do not vary with time which will be demonstrated in the aforementioned empirical formula for the electron mass and thus, subsequently the proton-to-electron mass ratio, the fine structure constant as well as for the gravitational constant.

- by Nikola Perkovic
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- Physics, Theoretical Physics, Elementary Particle Physics, Quantum Physics

Forty years ago, the first author deliberately allowed the swing and the punch bag to hit him. He was convinced that the force hitting him was much higher than the sum of the few pushes. However, his physics teacher at that time told him otherwise. Now, after his retirement, he met the other authors and did the mathematics to reconfirm his conviction. The theory clearly predicts that we can Extract Energy from Gravity. The experiments already done by the third author and demonstrated in 2000 proved the correctness of the theory. The theory also pointed to the design principles of dozens or thousands of possible machines. The energy crisis of the World is effectively over.

- by Chess Inventor
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- Physics, Energy, Alternative Energy, Gravity

In this paper we propose a new model for the p-median problem. In the standard p-median problem it is assumed that each demand point is served by the closest facility. In many situations (for example, when demand points are communities of customers and each customer makes his own selection of the facility) demand is divided among the facilities. Each customer selects a facility which is not necessarily the closest one. In the gravity p-median problem it is assumed that customers divide their patronage among the facilities with the probability that a customer patronizes a facility being proportional to the attractiveness of that facility and to a decreasing utility function of the distance to the facility. The model is analyzed and heuristic solution procedures are proposed. Computational experiments using a set of test problems, provide excellent results.

- by Zvi Drezner
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- Modeling, Localization, Multidisciplinary, Gravity

We show how one can measure the speed of gravity only using gravitational phenomena. Our approach offers several ways to measure the speed of gravity (light) and checks existing assumptions about light (gravity) in new types of experiments. The speed of light is included in several well-known gravita-tional formulas. However, if we can measure this speed from gravitational phenomena alone, then is it the speed of light or the speed of gravity we are measuring? We think it is more than a mere coincidence that they are the same. In addition, even if it is not possible to draw strong conclusions now, our formulations support the view that there is a link between electromagnet-ism and gravity. This paper also shows that all major gravity phenomena can be predicted from only performing two to three light observations. There is no need for knowledge of Newton's gravitational constant G or the mass size to complete a series of major gravity predictions.

- by Espen G A A R D E R Haug
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- Gravity, Speed of Light, Speed of Gravity

In this paper we will illustrate how to constrain unavoidable Kähler corrections for N = 1 supergravity (SUGRA) inflation from the recent Planck data. We will show that the non-renormalizable Kähler operators will induce in general non-minimal kinetic term for the inflaton field, and two types of SUGRA corrections in the potential — the Hubbleinduced mass (cH), and the Hubble-induced A-term (aH) correction. The entire SUGRA inflationary framework can now be constrained from (i) the speed of sound, cs, and (ii) from the upper bound on the tensor to scalar ratio, r⋆. We will illustrate this by considering a heavy scalar degree of freedom at a scale, Ms, and a light inflationary field which is responsible for a slow-roll inflation. We will compute the corrections to the kinetic term and the potential for the light field explicitly. As an example, we will consider a visible sector inflationary model of inflation where inflation occurs at the point of inflection, which can match the dens...

In this work we present the foundations of generalized scalar-tensor theories arising from vector bundle constructions, and we study the kinematic, dynamical and cosmological consequences. In particular, over a pseudo-Riemannian space-time base manifold, we define a fiber structure with two scalar fields. The resulting space is a 6-dimensional vector bundle endowed with a non-linear connection. We provide the form of the geodesics and the Raychaudhuri and general field equations, both in Palatini and metrical method. When applied at a cosmological framework, this novel geometrical structure induces extra terms in the modified Friedmann equations, leading to the appearance of an effective dark energy sector, as well as of an interaction of the dark mater sector with the metric. We show that we can obtain the standard thermal history of the universe, with the sequence of matter and dark-energy epochs, and furthermore the effective dark-energy equation-of-state parameter can lie in the...

- by Spyros Konitopoulos and +1
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- Mathematical Physics, Physics, Cosmology (Physics), General Relativity

Gravity seems to fail at large distances, and observed matter can only explain about 5% of the gravitational force involved in the galaxies’ motion. Science has thus invoked the presence of dark matter and dark energy to correspondingly... more

- by Alon Retter
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- Gravitation, Consciousness, Gravity, Gravity Model
- by Christopher Scotese
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- Earth Sciences, Geology, Tectonics, Potential Fields Geophysics

Abstract This paper reviews on the soil condition for three rivers at Carey Island namely Air Hitam, Judah and Keluang River. The activities on the island such as palm oil industries are believed affect the soil. Thus a study was carried out to determine the parameters of pH value, total sulphates, chloride content, total organic carbon (TOC), inorganic carbon (IC) and nitrogen in soil. The tests that have been conducted are Moisture Content Test, Specific Gravity Test, Atterberg Limit Test, pH Test, Total Sulphates Test and Total Chloride ...

- by Kamarudin Faizah
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- Environmental Science, Geochemistry, Soil Pollution, Soil contamination

Do Black Holes possess the ability to reverse the thermodynamic second law

- by Maria Anna van Driel
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- Physics, Theoretical Physics, Nuclear Physics, Plasma Physics

В монографии рассмотрен широкий круг вопросов, посвященных ре-зультатам исследований авторов пространственно-временных законо-мерностей современных проявлений сейсмической и вулканической ак-тивности. В книге представлен долгосрочный прогноз сейсмической и вулканической активности поясов сжатия Земли.
Описан положительный опыт краткосрочного прогнозирования силь-ных удаленных землетрясений на основании длиннопериодных гравита-ционных предвестников. Показана существенная роль влияния циклично-сти вулканической активности на глобальные климатические изменения.
Книга предназначена для ученых, специалистов и студентов в обла-стях наук о Земле.
V.Y.Khain, E.N.Khalilov
SPACE-TIME REGULARITIES OF SEISMIC AND VOLCANIC
ACTIVITY. Burgas, SWB, 2008, 304 p.
ISBN 978-9952-451-00-9
In the monograph has been considered the wide frame of questions, de-voted to the results of researches of the authors of space-time regularities of modern seismic and volcanic activity developments. In the book has been given the long-term prognosis of seismic and volcanic activity of the lines of Earth compression.
There has been described the positive experience of short-term prognosis of strong distanced earthquakes on basis of long-period gravitational harbin-gers. There also has been shown the essential role of influence of cyclicity of volcanic activity on global climatic changes.
The book is meant for scientists, specialists and students in the spheres of sciences about Earth.

- by Elchin Khalilov
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- Earth Sciences, Geology, Geophysics, Volcanology

This paper compares four observers (virtual sensors) of vehicle sideslip angle and lateral forces. The first is linear and uses a linear vehicle model. The remaining observers use an extended nonlinear model. The three nonlinear observers are: extended Luenberger observer, extended Kalman filter and sliding-mode observer. Modeling, model simplification, and observers are described, and an observability analysis is performed for the entire vehicle trajectory. The paper also deals with three different sets of sensors to see the impact of observers results. Comparison is first done by simulation on a valid vehicle simulator, and then observers are used on experimental data. Our study shows that observers are more accurate than simple models as regards unmeasurable variables such as sideslip angle and transversal forces. It also shows that speed of center of gravity is not an indispensable variable here.

- by joanny STEPHANT
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- Engineering, Vehicle Dynamics, State Estimation, Kalman Filter

Traditionally, gravitas denotes the inner source of movement towards the centre of the universe. In the mediaeval Latin tradition, the chief problem was to fit this notion within a coherent Aristotelian framework. As philosophers in the Renaissance begin to breach the constraints of Aristotelian natural philosophy, we see diverse attempts to conceive gravitas as a force also responsible for natural phenomena such as tides and free fall acceleration. The coexistence in the Renaissance of different Aristotelian and non-Aristotelian concepts of gravitas makes the latter a polysemic scientific term, whose meaning can be determined only after careful examination of the context in which it was employed.

- by Ivan Malara
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- Plato, Aristotle, Renaissance, History of Science

The Energy Problem (EP) in General Relativity (GR) is analyzed in the context of GR’s inconsistencies. EP is classified according to its local and global aspects. The local aspects of the EP include noncovariance of the energy-momentum pseudotensor (EMPT) of the gravitational field, non-uniqueness of the EMPT, asymmetry of EMPT and vanishing metric energy-momentum tensor. The global aspect of the EP relates to the lack of integral conservation laws due to the general difficulties in defining invariant integrals of tensors in non-Euclidean space. These difficulties are related to the lack of a precise definition of a reference frame in the GR. A reference frame is defined here as a differential manifold with an Affine connection. The resulting unique decomposition of the Levi-Civita connection into its Affine and nonmetric parts allows for a covariant definition of the gravitational energy-momentum tensor. It is pointed out that the invariance of the Lagrangian (or action functional) is a necessary but not sufficient condition to secure the covariance of the Lagrange-Euler field theory. A rigorous definition of the Lagrange Field Structure (LFS) on differential manifolds is proposed. A covariant generalization of the first Noether theorem for LFS is obtained. Different approaches to the EP are discussed.

- by Alexander Poltorak
- •
- Field Theory, Gravitation, General Relativity, Gravity Equation

In this research, I will try to give a simple, more general understanding of how gravity works. To do that, we will go in a journey to see what the old (Newtonian) and the new (Einstein) picture of gravity
is. And to season that, we will finish by introducing quantum Gravity. I will begin by defining the Kepler's laws for planetary motion, which Depending on it Newton created his theory for gravity, and we finish the section by Newtons gravity failure. Then I will start our discussion for Einstein's picture of gravity (general relativity), and cover rather some important topics, such as; Equivalence principle, Space-Time geometry, Einstein Field Equation...Etc., and I will finish the section by Einstein's answer to Newtonian failure. Finally I will give a very simple introduction to Quantum Gravity, and mainly discuss the some of the problems that phases the theory to be perfect.

- by Daryan Abdalla
- •
- Physics, Theoretical Physics, Quantum Physics, Gravitation

Composite metal foam (CMF), a new material belonging to the class of advanced cellular and porous materials, has been processed using gravity casting technique for the first time at North Carolina State University. This material comprises of steel hollow spheres and a solid aluminum alloy matrix. The energy absorption behavior of the material under static compression has been studied extensively. Experimental results show that CMF not only has a higher energy absorption capability than that of other commercially available metal foams produced from similar materials, but also possess a higher strength to density ratio. The microstructural analysis of the material was used to study and explain the formation of different phases at the aluminum-steel interface and their effect on the deformation behavior of the foam under compression. As the result of high strength and strain rates, the increase in energy absorption of the composite metal foam samples observed ranges over 30 times compared to that of 100% Al foams and over twice compared to that of 100% steel foams.

The use of GPS for the estimation of orthometric heights in a given region, with the help of existing levelling data requires the determination of a local geoid and the bias between the local levelling and the one implicitly defined when... more

- by Mohamed Aissa Meslem
- •
- Evaluation, Global Positioning System, Physical Geodesy, Gravimetry

People suffering from migraines, sleep apnea, glaucoma, memory loss, stroke, ADHD, and even impotence may benefit from new sleep research, which has discovered how sleep position impacts brain and head circulation, and can create many... more

In our previous article in reference [1], we were able to reformulate Maxwell's equations in a simplified and microscopic form. This article on the other hand is a follow-up of the aforementioned article but in this case it is shown that gravity may have electromagnetic origins, using as basis this reformulated Maxwell's equations. As a matter of fact, it is suggested in this article that thorough experimental investigations with neutrons could help us really understand gravity fundamentally. This however is based on the fact that a certain property of neutrons was calculated in this article using the assumption of the electromagnetic origins of gravity and this calculated value seems to correspond with the data that was obtained from an experiment performed some time ago (over 50 years ago) by Shull et al-see the article in reference [2]. Also, the rotation curve of galaxies, especially the spiral ones is revisited and it's shown that the assumption of the electromagnetic origins of gravity can explain it. This paper may also be handy to those who seek a unified/single theoretical framework for all fundamental forces.

- by Clinton O Onye
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- Mathematical Physics, Physics, Theoretical Physics, Electromagnetism

Science and religion seem to have been at odds with each other throughout history. This has affected the course of humanity and how society has prejudice towards either science or religion. Atheist scientists believe in what they know because they believe in reason and think that theists are unreasonable. The paper brings the problems facing humanity today between science, religion, and secularism within societies. The followers of each could be fanatics of their own group. The paper tries to reconcile the debate between atheists and theists, under the microscope of science. This study makes an analogy of G-d and gravity. It shows that the power of reason used by scientists to deduce gravity is the exact same reasoning that theists use to believe in G-d. The study goes beyond philosophical arguments and travels deep into the core principles of the human intellect of scientists and theologians to understand what they believe. It unravels the truth behind the reasoning of why different humans believe in what appears to be completely different things. The study uses elements of modern science and its cosmological worldview, such as singularity, spacetime, black holes, and quantum physics. It shows parallelism of modern scientific theories with various world Scriptures, such as Hindu and Islamic texts. This study does not argue the truth of any specific religion, but rather argues the existence of G-d from a broader perspective, using the exact same principles scientists use to formulate their worldview of the universe. This study shows the rationality and irrationality in the argumentative battle between science and religion. It attempts to end the debate and dispute between science and religion by understanding the truths behind them. It concludes that anyone who believes that the other is wrong is irrational, and that in reality science and religion complement one another. A theologian must also be a scientist, and a scientist must also be a theologian.

- by Abdulla Galadari
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- Religion, Physics, Quantum Physics, Philosophy of Science

Two identical objects are simultaneously projected vertically upward with the same initial speed in a uniform gravitational field and then return to their starting point. One object is subject to a resistive force proportional to the nth power of its speed where n ≥ 0, such as linear (Stokes) drag for n = 1 or quadratic (Newtonian) drag for n = 2. The other object moves through vacuum with no resistance. Which object returns to its starting point first? It is shown analytically that the object subject to drag always wins the race if n ≥ 1, but that either object can win otherwise, depending on the ratio of the launch speed to the terminal speed of the object subject to drag if 0 < n < 1 or depending on the ratio of the frictional acceleration to the gravitational acceleration if n = 0. These analytical results are confirmed by Euler–Cromer numerical integration of the equations of motion.

- by Trevor Lipscombe
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- Physics, Gravity, Mathematical Sciences, Time of Flight

Sustainable development of coastal areas depends fundamentally on the availability and comprehensive analysis of precise and up-to-date geospatial datasets. This study aims to develop an integrated geomatics approach for collecting and analyzing heterogeneous datasets within Geographic Information Systems (GIS) environment to predict potential risks of sea level variations over the Nile delta in 2025. Datasets include tide gauge (TG) records span 2008-2018, Global Navigations Satellite System (GNSS) observations to estimate land subsidence and consequently, absolute sea level rise, terrestrial high-accuracy Digital Elevation Model (DEM), and high-resolution satellite imageries were integrated to analyze and evaluate the impact of sea level rise on the coastal area of the Nile delta. Based on the available TG records over five sites, the statistical prediction has been carried out to forecast sea water variations in the next five years over the study area. Next, potentially inundated areas have been delineated for two cases: Mean Sea Level (MSL) and storm surges potential risks (High High water level (HHWL). The results indicate that the flooded area based on the MSL scenario represents only 5% of the total area of the entire study region, contrasting to earlier un-realistic estimates. Moreover, it has been found that the storm surge case produces potential risks 118% higher than those of MSL. Also, digital maps depicting all possible hazardous areas have been developed. Finally, it can be concluded that the presented integrated approach proves to be significantly effective in risk assessment over the Nile delta, helpful for decision makers to plan actions needed in coastal zone management, and it is reasonable to be applied in other similar regions worldwide.

- by Essam Al_krargy and +1
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- Geodesy, GPS Applications, Global Positioning System, Physical Geodesy

Steve Paxton: Drafting Interior Techniques is a collective reader/companion to Steve Paxton's life and work edited by Romain Bigé at the occasion of a retrospective exhibition that took place in Lisbon, Portugal. It offers contributions from dancers, philosophers & dance theorists: Delfim Sardo, Romain Bigé, João Fiadeiro, Julie Perrin, Daniel Lepkoff, Bojana Cvejić, Alice Godfroy, Nancy Stark Smith, Hubert Godard, André Lepecki, Yvonne Rainer, Martin Nachbar, Ramsay Burt, Bebe Miller, Patricia Kuypers, Colleen Bartley, as well as a portfolio comprised of photographs by Babette Mangolte, Bill Arnold, Peter Moore, & many others.

- by Emma Bigé and +3
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- Improvisation, Dance Studies, Dancing, Phenomenology of Touch

We always find ourselves at the present time, which occupies only one moment. This moment is the state of rest and we can observe motion only with the help our memory, that is, by experience. If motion were absolute, then we could be in the past, present, and future, we could travel in time. In reality, we compare what was before with what is now and thus comprehend the change, which we interpret as movement. If we did not have memory, we would not be able to comprehend change, we would always see the present image. Once again, it all depends on which angle we consider the given phenomenon. From the point of view of the present time, there is always a state of rest; from the point of view of experience – there is motion. The state of rest and motion occur simultaneously. The Universe just exists; it exists always at the present time and always takes all its places.

- by Andriy Bilousov
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- Cognitive Science, Energy, Johannes Kepler, Solar

O presente artigo tem o objetivo de discutir o filme de suspense/drama hollywoodiano de temática espacial “Gravidade” sob um olhar estético. Para isso, analisará o filme como obra de arte sob os preceitos de Walter Benjamin, colocará em questão o papel do filme na Indústria Cultural de Theodor Adorno e, por fim, levantará a discussão sobre a experiência estética proporcionado por ele a seus espectadores através de elementos visuais, sonoros e de enredo.

- by Arthur Medeiros
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- Cinema, Comunicação, Estética, Gravity

This research is to investigate the effects of deformable panels on reducing the seaward displacement, settlement and tilting of caisson quay walls. In this regard, a series of shaking table 1-g tests are performed for a 1 25 scaled-down caisson quay wall with two different seabed interface conditions. Here, the wall is tested in two cases: with and without (no-mitigation case) applying the deformable panels. Being installed behind the walls, the panels applied in the tests have different mechanical properties. In the model test, the harmonic base motions are used with constant frequency and amplitude. In all tests, the foundation soil beneath the caisson wall is assumed as dense and non liquefiable. However, in order to reproduce a loose backfill situation in the model, the backfill soil is constructed with relative density of 25%. Furthermore, to support the experimental results, a series of finite difference effective-stress analyses are performed in the prototype scale. The mitigation results show that the deformable panels can significantly decrease the seaward movement, settlement and inclination of wall as well as the total pressure recorded behind the caisson wall. Here, these panels are called Displacement Reducer Panels (DRP) based on the obtained results.

- by MAJID MORADI
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- Civil Engineering, Ocean Engineering, Numerical Analysis, Gravity