Academic literature on the topic 'Gravity law model'
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Journal articles on the topic "Gravity law model"
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Sharma, Ajay Kumar, and Murli Manohar Verma. "Power-law Inflation in the f(R) Gravity." Astrophysical Journal 926, no. 1 (February 1, 2022): 29. http://dx.doi.org/10.3847/1538-4357/ac3ed7.
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Abstract We investigate a form of f ( R ) = R 1 + δ / R c δ and study the viability of the model for inflation in the Jordan and the Einstein frames. We have extended this form to f ( R ) = R + R 1 + δ / R c δ in an attempt to solve the problems of the former model. This model is further analyzed by using the power spectrum indices of inflation and the reheating temperature. During the inflationary evolution, the model predicts a value of the δ parameter very close to one (δ = 0.98), while the reheating temperature T re ∼ 10 16 GeV at δ = 0.98 is consistent with the standard approach to inflation and observations. We calculate the slow roll parameters for the minimally coupled scalar field within the framework of our models. It is found that the values of the scalar spectral index and tensor-to-scalar ratio are very close to the recent observational data, including those released by Planck. Further, we find the scalar spectral index and the tensor-to-scalar ratio are exactly the same in the first model because the Jordan and the Einstein frames are conformally equivalent. We also attempt to provide a constraint through the non-Gaussianity parameter.
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Wang, Hao, Xiao-Yong Yan, and Jinshan Wu. "Free utility model for explaining the social gravity law." Journal of Statistical Mechanics: Theory and Experiment 2021, no. 3 (March 1, 2021): 033418. http://dx.doi.org/10.1088/1742-5468/abee18.
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GOSWAMI, UMANANDA DEV, and KABITA DEKA. "COSMOLOGICAL DYNAMICS OF f(R) GRAVITY SCALAR DEGREE OF FREEDOM IN EINSTEIN FRAME." International Journal of Modern Physics D 22, no. 14 (December 2013): 1350083. http://dx.doi.org/10.1142/s0218271813500831.
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f(R) gravity models belong to an important class of modified gravity models where the late time cosmic accelerated expansion is considered as a manifestation of the large scale modification of the force of gravity. f(R) gravity models can be expressed in terms of a scalar degree of freedom by redefinition of model's variable. The conformal transformation of the action from Jordan frame to Einstein frame makes the scalar degree of freedom more explicit and can be studied conveniently. We have investigated the features of the scalar degree of freedoms and the consequent cosmological implications of the power-law (ξRn) and the Starobinsky (disappearing cosmological constant) f(R) gravity models numerically in the Einstein frame. Both the models show interesting behavior of their scalar degree of freedom and could produce the accelerated expansion of the universe in the Einstein frame with the negative equation of state of the scalar field. However, the scalar field potential for the power-law model is the well-behaved function of the field, whereas the potential becomes flat for higher value of field in the case of the Starobinsky model. Moreover, the equation of state of the scalar field for the power-law model is always negative and less than -1/3, which corresponds to the behavior of the dark energy, that produces the accelerated expansion of the universe. This is not always the case for the Starobinsky model. At late times, the Starobinsky model behaves as cosmological constant Λ as behaves by power-law model for the values of n → 2 at all times.
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Sharif, M., and Ayesha Ikram. "Thermodynamics in f(G,T) Gravity." Advances in High Energy Physics 2018 (2018): 1–11. http://dx.doi.org/10.1155/2018/2563871.
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This paper explores the nonequilibrium behavior of thermodynamics at the apparent horizon of isotropic and homogeneous universe model in f(G,T) gravity (G and T represent the Gauss-Bonnet invariant and trace of the energy-momentum tensor, resp.). We construct the corresponding field equations and analyze the first as well as generalized second law of thermodynamics in this scenario. It is found that an auxiliary term corresponding to entropy production appears due to the nonequilibrium picture of thermodynamics in first law. The universal condition for the validity of generalized second law of thermodynamics is also obtained. Finally, we check the validity of generalized second law of thermodynamics for the reconstructed f(G,T) models (de Sitter and power-law solutions). We conclude that this law holds for suitable choices of free parameters.
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Chen, Yanguang. "The distance-decay function of geographical gravity model: Power law or exponential law?" Chaos, Solitons & Fractals 77 (August 2015): 174–89. http://dx.doi.org/10.1016/j.chaos.2015.05.022.
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Wu, Qimeng, Melle T. J. J. M. Punter, Thomas E. Kodger, Luben Arnaudov, Bela M. Mulder, Simeon Stoyanov, and Jasper van der Gucht. "Gravity-driven syneresis in model low-fat mayonnaise." Soft Matter 15, no. 46 (2019): 9474–81. http://dx.doi.org/10.1039/c9sm01097a.
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We show that forced syneresis in model low fat mayonnaise, a colloid polymer mixture, can be described as a gravity-driven porous flow through the densely packed emulsion, explainable with a model based on Darcy's law.
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Fu, Yanbin, Xiuling Wang, Sizhan Zhang, and Yong Yang. "Modelling of Permeation Grouting considering Grout Self-Gravity Effect: Theoretical and Experimental Study." Advances in Materials Science and Engineering 2019 (November 27, 2019): 1–16. http://dx.doi.org/10.1155/2019/7968240.
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Self-gravity is one key parameter for behavior characterization of grout permeation and diffusion. This study proposes mathematical models for permeation grouting with consideration of grout self-gravity effect. The models concerning power law, Bingham, and Newtonian grouts are based on the generalized Darcy’s law and spherical diffusion theory. In addition, a prediction model of grout concretion dimension used for Bingham grout was developed. An analysis of the injection pressure distribution law and a comparative evaluation of diffusion radius considering self-gravity effect using established models were conducted subsequently. Moreover, grouting experiments were performed to check and verify the prediction model. The experimental results showed that injection pressure decreases linearly with increase of diffusion radius for the power-law grout, while nonlinear decrease of injection pressure was confirmed in Bingham and Newtonian grouts in this case. Three grouts approximately diffuse in an “ellipsoidal” shape, and it is confirmed that the diffusion radius is closely related to grout self-gravity. The Newtonian grout produces the maximum diffusion radius compared with the other two grouts whether the gravity effects were considered or not. The grout quantity under a smaller water-to-cement w/c ratio exhibits a significant difference and undergoes two increasing stages, whereas the quantity simply tends to be stable after it reaches its maximum in terms of the larger w/c ratios. The constructed dimension prediction model agrees well with the experimental results, which can be helpful for design and assessment of the grouting scheme.
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Moussa, Mohamed. "Constraining unparticle-inspired model parameters using dwarf stars." International Journal of Modern Physics D 30, no. 05 (February 23, 2021): 2150031. http://dx.doi.org/10.1142/s0218271821500310.
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The unparticle-inspired model of gravity suggested by Georgi is based on that the standard model (SM) may contain a massive but scale invariant particles, which can be exchanged between SM massive particles, leading to a new force called ungravity. This would add a perturbed term to the Newtonian law of gravity at low energy. We use the minimum mass of hydrogen burning (MMHB) to constrain the relevant parameters of unparticle inspired model of gravity, on scales [Formula: see text] and [Formula: see text].
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Kuiroukidis, A. "A class of simple bouncing and late-time accelerating cosmologies in f(R) gravity." International Journal of Modern Physics D 27, no. 05 (April 2018): 1850055. http://dx.doi.org/10.1142/s0218271818500554.
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We consider the field equations for a flat FRW cosmological model, given by Eq. (??), in an a priori generic [Formula: see text] gravity model and cast them into a, completely normalized and dimensionless, system of ODEs for the scale factor and the function [Formula: see text], with respect to the scalar curvature [Formula: see text]. It is shown that under reasonable assumptions, namely for power-law functional form for the [Formula: see text] gravity model, one can produce simple analytical and numerical solutions describing bouncing cosmological models where in addition there are late-time accelerating. The power-law form for the [Formula: see text] gravity model is typically considered in the literature as the most concrete, reasonable, practical and viable assumption [see S. D. Odintsov and V. K. Oikonomou, Phys. Rev. D 90 (2014) 124083, arXiv:1410.8183 [gr-qc]]. However even without assuming a power-law form for the [Formula: see text] gravity model, the formulation of the field equations, that is suggested in this paper, is according to the author’s viewpoint quite generic in order to analyze the resulting field equations, without any further assumptions. Possibility of extending these results is briefly discussed.
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Debnath, Partha Sarathi, and Bikash Chandra Paul. "Cosmological models in R2 gravity with hybrid expansion law." International Journal of Geometric Methods in Modern Physics 18, no. 09 (June 11, 2021): 2150143. http://dx.doi.org/10.1142/s0219887821501437.
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In this paper, evolution of a Friedmann–Robertson–Walker universe is studied in a higher derivative theory of gravity. The relativistic solutions admitting hybrid expansion law of the universe are explored here. Hybrid expansion law is a general form of scale factor from which one can recover both the power-law expansion and exponential expansion as a special case. The hybrid expansion law is interesting as it addresses the early deceleration phase and presents accelerating phase satisfactorily. It is found that an inflationary scenario with hybrid expansion law is permitted in the [Formula: see text] gravity fairly well. We consider universe filled with cosmic fluid that describes by an equation of state (EoS) parameter which varies with time. Consequently, we analyze the time variation of energy density parameter, cosmic pressure, equation of state parameter, deceleration parameter and jerk parameter in the cosmological model. The constraints of the model parameters imposed by the cosmological observational data set are determined. The present value of the deceleration parameter [Formula: see text], EoS parameter and the epoch at which the transition of decelerated phase to accelerated phase are estimated. In the higher derivative theory, we obtain some new and interesting cosmological solutions relevant for building cosmological models.
Dissertations / Theses on the topic "Gravity law model"
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McCraney, Joshua Thomas. "Analysis of Capillary Flow in Interior Corners : Perturbed Power Law Similarity Solutions." PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2725.
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The design of fluid management systems requires accurate models for fluid transport. In the low gravity environment of space, gravity no longer dominates fluid displacement; instead capillary forces often govern flow. This thesis considers the redistribution of fluid along an interior corner. Following a rapid reduction of gravity, fluid advances along the corner measured by the column length z = L(t), which is governed by a nonlinear partial differential equation with dynamical boundary conditions. Three flow types are examined: capillary rise, spreading drop, and tapered corner. The spreading drop regime is shown to exhibit column length growth L ~ t2/5, where a closed form analytic solution exists. No analytic solution is available for the capillary rise problem. However, a perturbed power law similarity solution is pursued to approximate an analytic solution in the near neighborhood of the exact solution for the spreading drop. It is recovered that L ~ t1/2 for the capillary rise problem. The tapered corner problem is not analytically understood and hence its corresponding L is undocumented. Based on the slender corner geometry, it is natural to hypothesize the tapered corner column length initially behaves like the capillary rise regime, but after sufficient time has elapsed, it transitions into the spreading drop regime. This leads to a conjecture that its column length growth L is restricted to t2/5 < L < t1/2. To verify this conjecture an explicit finite difference numerical solution is developed for all three regimes. As will be shown, the finite difference scheme converges towards the analytic solutions for the spreading drop and capillary rise regimes. From this we assume the finite difference scheme is accurate for corner flows of similar geometries, and thus apply this scheme the more onerous criteria of the tapered corner. Numerical results support the conjectured L behavior for the tapered corner. Understanding the dynamics of such flows and responses to various geometries offers design advantages for spacecraft waste-management systems, fuel control, hydration containment, cryogenic flows, and a myriad of other fluid applications.
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Lenormand, Maxime. "Initialiser et calibrer un modèle de microsimulation dynamique stochastique : application au modèle SimVillages." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2012. http://tel.archives-ouvertes.fr/tel-00822114.
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Le but de cette thèse est de développer des outils statistiques permettant d'initialiser et de calibrer les modèles de microsimulation dynamique stochastique, en partant de l'exemple du modèle SimVillages (développé dans le cadre du projet Européen PRIMA). Ce modèle couple des dynamiques démographiques et économiques appliquées à une population de municipalités rurales. Chaque individu de la population, représenté explicitement dans un ménage au sein d'une commune, travaille éventuellement dans une autre, et possède sa propre trajectoire de vie. Ainsi, le modèle inclut-il des dynamiques de choix de vie, d'étude, de carrière, d'union, de naissance, de divorce, de migration et de décès. Nous avons développé, implémenté et testé les modèles et méthodes suivants : 1 / un modèle permettant de générer une population synthétique à partir de données agrégées, où chaque individu est membre d'un ménage, vit dans une commune et possède un statut au regard de l'emploi. Cette population synthétique est l'état initial du modèle. 2 / un modèle permettant de simuler une table d'origine-destination des déplacements domicile-travail à partir de données agrégées. 3 / un modèle permettant d'estimer le nombre d'emplois dans les services de proximité dans une commune donnée en fonction de son nombre d'habitants et de son voisinage en termes de service. 4 / une méthode de calibration des paramètres inconnus du modèle SimVillages de manière à satisfaire un ensemble de critères d'erreurs définis sur des sources de données hétérogènes. Cette méthode est fondée sur un nouvel algorithme d'échantillonnage séquentiel de type Approximate Bayesian Computation.
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Horta, Bernús Ricard. "Lleis d'escala i complexitat estructural de les infraestructures tecnològiques. Els sistemes biològics com a analogia pel disseny i optimització del transport i distribució de l'energia elèctrica." Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/145689.
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Within the paradigm of sustainability, this thesis aims to provide complementary views to the conventional engineering in order to put forward tools that facilitate, on the one hand the search of solutions to improve the design of high-voltage power lines , and on the other hand to optimize their networks. As per the improving of a high-voltage line design, Scaling Laws and Gravity Models are used to provide new variables to estimate calculation of the electricity demand of a certain area. This article proposes modifications to the vector diagram of a transmission line operation, known as a Perrine-Baum Diagram to incorporate the new variables proposed with the objective to use this diagram as an application tool in real projects. Regarding the electric power networks, this work applies the analysis tools provided by the theories of Complex Networks to study its topology and spatial features in order to suggest more optimal designs.Dins del paradigma de la sostenibilitat, aquesta tesi pretén aportar punts de vista complementaris als de l’enginyeria convencional amb l’objectiu de proposar eines que facilitin per una banda, trobar solucions per millorar el disseny de les línies elèctriques d’alta tensió, i per una altra optimitzar les xarxes constituïdes per aquestes. Pel que fa a la millora del disseny d’una línia d’alta tensió, s’han utilitzat les teories de les Lleis d’Escala i els Models Gravitacionals per aportar noves variables als càlculs de previsió de demanda elèctrica d’una regió. S’han proposat modificacions al diagrama vectorial de funcionament d’una línia elèctrica, conegut com a Diagrama Perrine-Baum, per incorporar les noves variables proposades amb l’objectiu que aquest diagrama pugui ser una eina d’aplicació en projectes reals. Pel que fa a les xarxes elèctriques s’han aplicat les eines d’anàlisi aportades per les teories de Xarxes Complexes per estudiar la seva topologia i les característiques espacials, amb l’objectiu de proposar dissenys més òptims.
Books on the topic "Gravity law model"
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Zeitlin, Vladimir. Wave Turbulence. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198804338.003.0013.
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Main notions and ideas of wave (weak) turbulence theory are explained with the help of Hamiltonian approach to wave dynamics, and are applied to waves in RSW model. Derivation of kinetic equations under random-phase approximation is explained. Short inertia–gravity waves on the f plane, short equatorial inertia–gravity waves, and Rossby waves on the beta plane are then considered along these lines. In all of these cases, approximate solutions of kinetic equation, annihilating the collision integral, can be obtained by scaling arguments, giving power-law energy spectra. The predictions of turbulence of inertia–gravity waves on the f plane are compared with numerical simulations initialised by ensembles of random waves. Energy spectra much steeper than theoretical are observed. Finite-size effects, which prevent energy transfer from large to short scales, provide a plausible explanation. Long waves thus evolve towards breaking and shock formation, yet the number of shocks is insufficient to produce shock turbulence.
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Zeitlin, Vladimir. Simplifying Primitive Equations: Rotating Shallow-Water Models and their Properties. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198804338.003.0003.
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In this chapter, one- and two-layer versions of the rotating shallow-water model on the tangent plane to the rotating, and on the whole rotating sphere, are derived from primitive equations by vertical averaging and columnar motion (mean-field) hypothesis. Main properties of the models including conservation laws and wave-vortex dichotomy are established. Potential vorticity conservation is derived, and the properties of inertia–gravity waves are exhibited. The model is then reformulated in Lagrangian coordinates, variational principles for its one- and two-layer version are established, and conservation laws are reinterpreted in these terms.
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Scott, Juliette R. Legal Translation Outsourced. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780190900014.001.0001.
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This highly interdisciplinary practitioner research explores the outsourced legal translation environment, with a view to optimizing fundamental aspects of procurement—commissioning and performance. The results of a global survey are analysed: participants comprised 84 principals, for the most part from leading law firms and corporations, and 303 legal translation practitioners (41 countries, 6 continents). Concepts from corporate agency theory are used to shed light on market dysfunctions, such as a tortuous chain of supply, while perspectives from genre theory, comparative law, and functionalist translation studies are applied to offer a multidimensional model for legal translation performance, and to foreground its risks and constraints. Fitness-for-purpose is examined as a workable quality criterion associated with translation briefs supplied. Professionalization and empowerment are raised as key factors with potential to significantly improve target text quality. Extensive fieldwork has brought to light ‘hot spots’ for risk, such as severely impeded information flows, insufficient interaction between market actors, and deficient translation briefs. The groundwork for dissemination to practice has already been laid, for example using a briefing template specifically developed for the outsourcing of legal translation, set to benefit commissioning clients by increasing the fitness-for-purpose of translated texts. The types of legal texts outsourced have proved in many instances to be highly sensitive, which further emphasizes the gravity of the problem and the need to take action.
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Wittman, David M. General Relativity and the Schwarzschild Metric. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199658633.003.0018.
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Previously, we saw that variations in the time part of the spacetime metric cause free particles to accelerate, thus unifying gravity and relativity; and that orbits trace those accelerations, which follow the inverse‐square law around spherical source masses. But a metric that empirically models orbits is not enough; we want to understand how any arrangement of mass determines the metric in the surrounding spacetime. This chapter describes thinking tools, especially the frame‐independent idea of spacetime curvature, that helped Einstein develop general relativity. We describe the Einstein equation, which determines the metric given a source or set of sources. Solving that equation for the case of a static spherical mass (such as the Sun) yields the Schwarzschild metric. We compare Schwarzschild and Newtonian predictions for precession, the deflection of light, and time delay of light; and we contrast the effects of variations in the time and space parts of the metric.
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Zaitsev, Fedor, and Vladimir Bychkov. Mathematical modeling of electromag-netic and gravitational phenomena by the methodology of continuous media mechanics. LCC MAKS Press, 2021. http://dx.doi.org/10.29003/m2011.978-5-317-06604-8.
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The book of well-known Russian scientists systematically presents a new theoretical approach to studying nature's fundamental phenomena using the hypothesis of the physical vacuum, or the ether, as some environment in which all the processes develop. In the proposed studies, the ether is represented as some one-component continuous media that satisfies generally accepted conservation laws: of matter and momentum. From the appropriate two equations, a number of consequences are obtained to which a physical interpretation is given. For the first time, 150 years after studies of Faraday and Maxwell, it is shown that these single premises mathematically give basic physical laws established experimentally: the Maxwell equations, the Lorentz force, the Gauss theorem; the laws: Coulomb, Biot - Savard, Ampere, electromagnetic induction, Ohm, Joule - Lenz, Wiedemann - Franz, universal gravitation, and etc. Details of mechanisms of many processes, that seemed previously paradoxical, have been disclosed. A method of the model substantiation adopted in the mathematical modeling methodology allows to conclude that the presented mathematical model of the ether adequately describes electromagnetic and gravitational processes. Qualitative and quantitative analysis of hundreds of known and new experimental facts allows in the methodology of physics, as science summarizing the experiments data, to confirm a conclusion about the existence of the ether (physical vacuum). The content of the book is based on the works of authors done during the last fourteen years. Many results are published for the first time. The book is intended for specialists in the field of electrodynamics, electrical engineering, gravity and kinetics, as well as for graduate students and students, interested in the fundamental principles of these scientific directions. This book is unique in terms of the comprehensive consideration of the problem and the depth of its analysis.
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Schliesser, Eric. Newton's Metaphysics. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780197567692.001.0001.
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This collection of papers by a leading philosophical Newton scholar offers new interpretations of Newton’s account of space, gravity, motion, inertia, and laws—all evergreens in the literature. The volume also breaks new ground in focusing on Newton’s philosophy of time, Newton’s views on emanation, and Newton’s modal metaphysics. In addition, the volume is unique in exploring the very rich resonances between Newton’s and Spinoza’s metaphysics, including the ways in which Newton and his circles responded to the threat by, and possible accusation of, Spinozism. Seven chapters have been published before and will be republished with minor corrections. Two of these chapters are coauthored: one with Zvi Biener and one with Mary Domski. Two chapters are wholly new and are written especially for this volume. In addition, the volume includes two postscripts with new material responding to critics. A main part of the argument of these essays is not just to characterize the conceptual choices Newton made in developing the structure of theory that would facilitate the kind of measurements characteristic of the Newtonian style, but also to show that these choices, in turn, were informed by intellectual aspirations that brought Newton’s edifice into theological and philosophical conflicts. As these conflicts became acute, these drove further conceptual refinement. Many of the essays in the volume relate the development of Newton’s philosophy to the philosophies of his contemporaries, especially Spinoza and Samuel Clarke.
Book chapters on the topic "Gravity law model"
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Forger, Michael. "Non-local conservation laws for non-linear sigma models with fermions." In Field Theory, Quantum Gravity and Strings, 221–41. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/3-540-16452-9_14.
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Bermúdez, Alfredo. "Some Case Studies in Environmental and Industrial Mathematics." In SEMA SIMAI Springer Series, 19–38. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-86236-7_2.
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AbstractThis presentation deals with four case studies in environmental and industrial mathematics developed by the mathematical engineering research group (mat+i) from the University of Santiago de Compostela and the Technological Institute for Industrial Mathematics (ITMATI). The first case involves environmental fluid mechanics: optimizing the location of submarine outfalls on the coast. This work, related to shallow water equations with variable depth, led us to develop a theory for numerical treatment of source terms in nonlinear first order hyperbolic balance laws. More recently, these techniques have been applied to solve Euler equations with source terms arising from numerical simulation of gas transportation networks when topography via gravity force is considered in the model. The last two problems concerns electromagnetism. One of them is related to nondestructive testing of car parts by using magnetic nanoparticles (the so-called magnetic particle inspection, MPI): mathematical modelling of magnetic hysteresis to simulate demagnetization. Finally, we present a mathematical procedure to reduce the computing time needed to achieve the stationary state of an induction electric machine when using transient numerical simulation.
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Shehab Ahmed Al-Banna, Ahmed. "Gravity Field Theory." In Gravitational Field [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.99959.
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Gravity keep all things on the earth surface on the ground. Gravity method is one of the oldest geophysical methods. It is used to solve many geological problems. This method can be integrated with the other geophysical methods to prepare more accepted geophysical model. Understanding the theory and the principles concepts considered as an important step to improve the method. Chapter one attempt to discuss Newton’s law, potential and attraction gravitational field, Geoid, Spheroid and geodetically figure of the earth, the gravity difference between equator and poles of the earth and some facts about gravity field.
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De Rújula, Alvaro. "Today’s Standard Models of Particles and Gravity." In Enjoy Our Universe, 129–31. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198817802.003.0023.
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The missing particle of the standard model: the “axion.” Our considerable ignorance concerning dark matter and the dark energy density of the Universe. No decent theory of quantum gravity. How all this sends us back to the drawing board, and to return to observations of the Universe, starting with Hubble’s law of its expansion.
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"Normalization of Fluctuation Modes and Curved Space Gauss's Law." In Brane-Localized Gravity, 109–32. WORLD SCIENTIFIC, 2005. http://dx.doi.org/10.1142/9789812703132_0016.
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Krishnamurti, T. N., H. S. Bedi, and V. M. Hardiker. "Initialization Procedures." In An Introduction to Global Spectral Modeling. Oxford University Press, 1998. http://dx.doi.org/10.1093/oso/9780195094732.003.0011.
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In this chapter we describe two of the most commonly used initialization procedures. These are the dynamic normal mode initialization and the physical initialization methods. Historically, initialization for primitive equation models started from a hierarchy of static initialization methods. These include balancing the mass and the wind fields using a linear or nonlinear balance equation (Charney 1955; Phillips 1960), variational techniques for such adjustments satisfying the constraints of the model equations (Sasaki 1958), and dynamic initialization involving forward and backward integration of the model over a number of cycles to suppress high frequency gravity oscillations before the start of the integration (Miyakoda and Moyer 1968; Nitta and Hovermale 1969; Temperton 1976). A description of these classical methods can be found in textbooks such as Haltiner and Williams (1980). Basically, these methods invoke a balanced relationship between the mass and motion fields. However, it was soon realized that significant departures from the balance laws do occur over the tropics and the upperlevel jet stream region. It was also noted that such departures can be functions of the heat sources and sinks and dynamic instabilities of the atmosphere. The procedure called nonlinear normal mode initialization with physics overcomes some of these difficulties. Physical initialization is a powerful method that permits the incorporation of realistic rainfall distribution in the model’s initial state. This is an elegant and successful initialization procedure based on selective damping of the normal modes of the atmosphere, where the high-frequency gravity modes are suppressed while the slow-moving Rossby modes are left untouched. Williamson (1976) used the normal modes of a shallow water model for initialization by setting the initial amplitudes of the high frequency gravity modes equal to zero. Machenhauer (1977) and Baer (1977) developed the procedure for nonlinear normal mode initialization (NMI), which takes into account the nonlinearities in the model equations. Kitade (1983) incorporated the effect of physical processes in this initialization procedure. We describe here the normal mode initialization procedure. Essentially following Kasahara and Puri (1981), we first derive the equations for vertical and horizontal modes of the linearized form of the model equations.
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"Gravity and Reference Models." In Gravity and Low-Frequency Geodynamics, 438–56. Elsevier, 1989. http://dx.doi.org/10.1016/b978-0-444-98908-6.50013-6.
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Ginsburgh, Victor, and Shlomo Weber. "Distances Matter." In How Many Languages Do We Need? Princeton University Press, 2011. http://dx.doi.org/10.23943/princeton/9780691136899.003.0005.
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The linguistic, genetic, and cultural distances discussed in Chapter 3 have important applications, and many economists have shown that they matter greatly. This chapter focuses on inter-country differences and their impact on trade, migration, translations, and certain aspects of voting behavior. Most applications of intercountry linguistic differences are based on what is now known as the gravity model, whose name comes from its analogy with Newton's 1687 law of universal gravitation. Section 1 is devoted to the best-known and most frequent application of the gravitational analogy: international trade flows. Section 2 discusses migrational flows. Section 3 analyzes the number of translations of literary works into and from various languages, whereas section 4 is devoted to a description of countries' voting patterns in the annual international Eurovision Song Contest.
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Sadrnia, Abdolhossein, Hossein Nezamabadi-Pour, Mehrdad Nikbakht, and Napsiah Ismail. "A Gravitational Search Algorithm Approach for Optimizing Closed-Loop Logistics Network." In Meta-Heuristics Optimization Algorithms in Engineering, Business, Economics, and Finance, 616–38. IGI Global, 2013. http://dx.doi.org/10.4018/978-1-4666-2086-5.ch020.
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Since late in the 20th century, various heuristic and metaheuristic optimization methods have been developed to obtain superior results and optimize models more efficiently. Some have been inspired by natural events and swarm behaviors. In this chapter, the authors illustrate empirical applications of the gravitational search algorithm (GSA) as a new optimization algorithm based on the law of gravity and mass interactions to optimize closed-loop logistics network. To achieve these aims, the need for a green supply chain will be discussed, and the related drivers and pressures motivate us to develop a mathematical model to optimize total cost in a closed-loop logistic for gathering automobile alternators at the end of their life cycle. Finally, optimizing total costs in a logistic network is solved using GSA in MATLAB software. To express GSA capabilities, a genetic algorithm (GA), as a common and standard metaheuristic algorithm, is compared. The obtained results confirm GSA’s performance and its ability to solve complicated network problems in closed-loop supply chain and logistics.
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Sun, Fengnan, Yan Zhu, Qiyou Cheng, Siwen Wang, and Xuyang Lin. "Analysis of Nonlinear Aeroelastic and Structural Characteristics of Wing / Multi External Storage System with High Aspect Ratio." In Advances in Transdisciplinary Engineering. IOS Press, 2022. http://dx.doi.org/10.3233/atde220068.
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Aiming at the problem of large deformation geometric nonlinearity of high aspect ratio wing/multi external storage system affected by aerodynamic, multi external storage and gravity loads, the nonlinear aeroelastic motion equation of wing is established by using medium deformation beam theory and quasi steady aerodynamic model, and the effects of geometric nonlinear deformation of high aspect ratio wing/multi external storage system on structural modal frequency Influence of vibration mode and flutter characteristics.The analysis results show that the influence of geometric nonlinear effect is mainly reflected in the first-order mode of lead-lag, and its flutter mechanism is flexural torsional coupling flutter dominated by the first-order mode of lead-lag. The random wing/multi plug-in system changes from vertical downward bending state to horizontal state, the influence of geometric nonlinear effect is weakened, and the amplitude of the first-order mode shape of lead-lag increases, Moreover, the variation trend of the first-order lead-lag and torsional modal frequencies slows down, which correspondingly reduces the variation amplitude of flutter velocity at the corresponding angle of attack, which shows that it has a certain positive effect on the flutter velocity by slowing down the geometric nonlinearity of the wing/multi plug-in system.
Conference papers on the topic "Gravity law model"
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Qin Yu, Zhiguang Qin, Yuming Mao, and Juebang Yu. "A novel gravity law-based survivability model for Ad Hoc network." In 2009 International Conference on Communications, Circuits and Systems (ICCCAS). IEEE, 2009. http://dx.doi.org/10.1109/icccas.2009.5250543.
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Yunkai Wei, Yuming Mao, and Qin Yu. "A gravity-law inspired survivability enhancement model for wireless sensor networks." In 2009 International Conference on Communications, Circuits and Systems (ICCCAS). IEEE, 2009. http://dx.doi.org/10.1109/icccas.2009.5250548.
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Sokolov, T., and T. Zemach. "On Gravity Currents in Power-Law Cross-Section Channels : The Effect of Vegetation." In Topical Problems of Fluid Mechanics 2023. Institute of Thermomechanics of the Czech Academy of Sciences; CTU in Prague Faculty of Mech. Engineering Dept. Tech. Mathematics, 2023. http://dx.doi.org/10.14311/tpfm.2023.026.
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We consider the propagation of gravity currents (GC), through an array of vertical obstacles, called vegetation, along channels of power-law cross-section (CS) shapes. We formulate a model and solve it numerically. Special attention is given to the similarity long-term behaviour of the current, for which the analytical solutions are available and compared to the numerical data.
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Hammad, Fayçal. "Density perturbations in f (R, ϕ)-gravity in general with an application to the (varying power)-law model." In Proceedings of the MG15 Meeting on General Relativity. WORLD SCIENTIFIC, 2022. http://dx.doi.org/10.1142/9789811258251_0102.
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Murphy, Benjamin M., Beth A. Todd, James F. Cuttino, and Linda C. Shackelford. "Developing a Finite Element Model of a Human Femur From Magnetic Resonance Images." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0010.
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Abstract Under the conditions of weightlessness, astronauts have a tendency to exhibit bone mineral loss in their spines and lower extremities (Oganov et al., 1992). According to Wolf’s law, bone adapts to functional demands by remodeling to reflect the distribution of stress placed on the bone (Bentzen et al., 1987). To prevent remodeling, NASA has suggested a plan of resistive exercises to produce the appropriate stress distributions to counteract the remodeling process. Prolonged bed rest studies are used by NASA to simulate a zero gravity environment on earth. During these bed rest studies, different exercises are performed on a device called the horizontal exercise machine (HEM). These exercises are the same type as those that are proposed for space flight.
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Kuznetsov, A. V., and N. Jiang. "A Model of Bioconvection of a Dilute Suspension of Gravitactic Microorganisms in an Isotropic Porous Medium." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/htd-24414.
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Abstract A new continuum model is formulated for bioconvection in a dilute suspension of swimming, gravitactic microorganisms in a porous medium. ‘Bioconvection’ is the name given to pattern-forming convective motions set up in suspensions of swimming microorganisms. ‘Gravitaxis’ describes the way of the swimming and means that microorganisms tend to swim against the gravity. The aim of this paper is to analyze collective behaviour and pattern formation in populations of swimming microorganisms. The existence and stability of a two-dimensional plume in a tall, narrow chamber with stress-free sidewalls is investigated. Governing equations include the Darcy law and the microorganism conservation equation. A conservative finite-difference scheme is used to solve these equations numerically.
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Ghodbane, Azeddine, Maarouf Saad, Jean-François Boland, and Claude Thibeault. "Sliding Mode Reconfigurable Control for Cosmic Rays Faults in Flight Systems." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-38118.
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In this paper, a FTFC system is designed to handle a cosmic rays fault affecting actuator control signal. The geometric approach is used to design the fault diagnosis module. This module determines the gravity of the fault and calculates its parameters. Based thereon, a new reconfigurable Sliding Mode Control law is designed and applied on the longitudinal linear model of the F-16 aircraft. Simulations are performed using Matlab®/Simulink® to show the effectiveness of the proposed approach.
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Romero, José A., Frank Otremba, and Alejandro A. Lozano-Guzmán. "Commodities and Rail Damage." In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-86008.
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A simplified roll-plane model is proposed to assess the effect of the vertical position of the center of gravity of the body-cargo system, on the rail fatigue life. A set of assumptions are made to simplify the analysis, including neglecting the bogie’s dynamic contribution to the wheel-rail forces. Three performance measures are defined to assess the effect of different dedicated railway cars on the rail fatigue life, including the fourth-power law, the load dispersion, and the rail fatigue. The simulation results suggest that the vertical position of the center of gravity of the body-cargo set, severely affects the fatigue life of the railway material, with the two-stack car being the most aggressive. For example, twice as aggressive as the gondola car.
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Wang, Qilin, Yan Li, Zhicheng Yu, and Bin Guo. "Numerical Simulation of Gravity-Driven Droplet Displacement on an Inclined Micro-Grooved Surface." In ASME 2016 5th International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/mnhmt2016-6529.
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Gravity-driven displacement of droplet on an inclined micro-grooved surface is studied using Pseudo-potential model of lattice Boltzmann method. To validate the numerical method, we find good agreement of the LB simulations with the pressure difference by Laplace’s law. The equilibrium contact angle of a droplet wetting on a smooth horizontal surface is studied as a function of the wettability, finding good agreement with an empirical scheme obtained with Young’s equation. The dynamic behavior of a droplet wetting on micro-grooved horizontal surface is found to be complex and greatly affected by the fraction of the grooved area and the groove width, the results indicate that the effect of grooves on contact angle is dependent on the fraction of the grooved area and the groove width has not a consistent effect on contact angles. For an inclined nonwetting micro-grooved surface, in given range, higher fraction of the grooved area and smaller groove width lead to greater benefit for droplet sliding down. What’s more, the results indicate that higher gravity value leads to a higher decrease of movement resistance of the droplet by decreasing the contact area between the droplet and solid surface.
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Kitazawa, Daisuke, Yoichi Mizukami, Masaaki Isobe, Hiromi Kinoshita, Mamoru Hirayama, Satoshi Ikeda, and Yoto Takeuchi. "Tank Model Testing of a Fish-Cage Flotation/Submersion System Using Flexible Hoses." In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-50240.
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A fish-cage flotation/submersion system using flexible hoses is proposed to achieve horizontally stable floating and sinking motions. Waterproof flexible hoses are inserted into polyethylene pipes installed at the top of the frame of the fish cage. These hoses flatten when they are devoid of air and water as the fish cage is submerged. The injection of high-pressure air regenerates buoyancy and enables the fish cage to rise in the water. The advantage of this system is the uniform, circumferential generation of buoyancy at the top of the frame, which suppresses inclination of the fish cage and concomitant deformation of the flexible chemical fiber nets. Tank model testing was carried out to examine the inclination and the floating velocity of the fish cage. Tauchi’s similarity law was applied to make a 1/30 model of the full-scale fish cage. The tank model of the fish cage was installed in the ocean engineering basin at the University of Tokyo, and it was made to float and sink in water with and without currents. The inclination and position of the fish cage were measured using video camera images. As a result, the proposed fish cage was observed to float stably in still water in contrast to systems based on the existing method. When subjected to water currents, the new fish cage inclined by a maximum of 18° just after leaving the bottom; the inclination was reduced with further ascension. The ratio of buoyancy to gravity, the rate of air injection, and the arrangement of the flexible hoses should be optimized to achieve a more stable motion. The floating velocity for the rising fish cage in still water was then analyzed. The drag coefficient of the fish cage, as calculated from experimental data, corresponded to that estimated from a structural analysis of the fish cage. Analysis projected accelerated motion for 0.02 s after the fish cage rose from the bottom, while acceleration lasted a few seconds in the tank model test. This is because uniformly accelerated motion was assumed in the analysis, while the acceleration actually varies from zero to a constant acceleration, because of the difference between gravity and the varying buoyancy of the flexible hoses.
Reports on the topic "Gravity law model"
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Thomas, M. D. Magnetic and gravity models, northern half of the Taltson Magmatic Zone, Rae Craton, Northwest Territories: insights into upper crustal structure. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/328244.
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A prominent magnetic low along an eastern portion of the Paleoproterozoic Taltson magmatic zone (TMZ) correlates mainly with the youngest granitoid in the zone, the peraluminous ca. 1936 Ma Konth granite. Flanking belts of higher magnetic intensity coincide mainly with slightly older Taltson plutonic rocks (e.g. ca. 1986 Ma Deskenatlata granodiorite, ca. 1955 Ma Slave granite) to the west and Neoarchean and/or Paleoproterozic gneisses of the Rae Craton to the east. A prominent gravity low along a portion of the northeastern margin of the TMZ correlates mainly with the Konth granite. Modelling of east-west magnetic and gravity profiles crossing the TMZ is used to investigate the geometrical and geological significance of these signatures. Modelling of the gravity low revealed a basin-like shape, with a maximum thickness of 14.9 km, for a composite unit of Konth-Slave magmatic suites. Magnetic modelling, the preferred technique north and south of the gravity minimum, yielded basin-like shapes for an essentially nonmagnetic Konth-Slave unit, but with much smaller maximum thicknesses of 5.0 and 6.5 km, respectively. Farther south in the TMZ, strongly magnetic units within mapped Konth and Slave granites preclude definition of a nonmagnetic Konth-Slave unit. Aside from the Slave unit, most other modelled magnetic units are generally steep and narrow and have fairly large magnetic susceptibilities. They are modelled to a depth of 6.2 km below sea level and have a steeply dipping, near-surface structural fabric extending to significant depth. Granitoids in the TMZ have previously been designated as ilmenite series or magnetite series, but modelled susceptibilities indicate that revisions to some designations may be required.
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Lahav, Ori, Albert Heber, and David Broday. Elimination of emissions of ammonia and hydrogen sulfide from confined animal and feeding operations (CAFO) using an adsorption/liquid-redox process with biological regeneration. United States Department of Agriculture, March 2008. http://dx.doi.org/10.32747/2008.7695589.bard.
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The project was originally aimed at investigating and developing new efficient methods for cost effective removal of ammonia (NH₃) and hydrogen sulfide (H₂S) from Concentrated Animal Feeding Operations (CAFO), in particular broiler and laying houses (NH₃) and hog houses (H₂S). In both cases, the principal idea was to design and operate a dedicated air collection system that would be used for the treatment of the gases, and that would work independently from the general ventilation system. The advantages envisaged: (1) if collected at a point close to the source of generation, pollutants would arrive at the treatment system at higher concentrations; (2) the air in the vicinity of the animals would be cleaner, a fact that would promote animal growth rates; and (3) collection efficiency would be improved and adverse environmental impact reduced. For practical reasons, the project was divided in two: one effort concentrated on NH₃₍g₎ removal from chicken houses and another on H₂S₍g₎ removal from hog houses. NH₃₍g₎ removal: a novel approach was developed to reduce ammonia emissions from CAFOs in general, and poultry houses in particular. Air sucked by the dedicated air capturing system from close to the litter was shown to have NH₃₍g₎ concentrations an order of magnitude higher than at the vents of the ventilation system. The NH₃₍g₎ rich waste air was conveyed to an acidic (0<pH<~5) bubble column reactor where NH₃ was converted to NH₄⁺. The reactor operated in batch mode, starting at pH 0 and was switched to a new acidic absorption solution just before NH₃₍g₎ breakthrough occurred, at pH ~5. Experiments with a wide range of NH₃₍g₎ concentrations showed that the absorption efficiency was practically 100% throughout the process as long as the face velocity was below 4 cm/s. The potential advantages of the method include high absorption efficiency, lower NH₃₍g₎ concentrations in the vicinity of the birds, generation of a valuable product and the separation between the ventilation and ammonia treatment systems. A small scale pilot operation conducted for 5 weeks in a broiler house showed the approach to be technically feasible. H₂S₍g₎ removal: The main goal of this part was to develop a specific treatment process for minimizing H₂S₍g₎ emissions from hog houses. The proposed process consists of three units: In the 1ˢᵗ H₂S₍g₎ is absorbed into an acidic (pH<2) ferric iron solution and oxidized by Fe(III) to S⁰ in a bubble column reactor. In parallel, Fe(III) is reduced to Fe(II). In the 2ⁿᵈ unit Fe(II) is bio-oxidized back to Fe(III) by Acidithiobacillus ferrooxidans (AF).In the 3ʳᵈ unit S⁰ is separated from solution in a gravity settler. The work focused on three sub-processes: the kinetics of H₂S absorption into a ferric solution at low pH, the kinetics of Fe²⁺ oxidation by AF and the factors that affect ferric iron precipitation (a main obstacle for a continuous operation of the process) under the operational conditions. H₂S removal efficiency was found higher at a higher Fe(III) concentration and also higher for higher H₂S₍g₎ concentrations and lower flow rates of the treated air. The rate limiting step of the H₂S reactive absorption was found to be the chemical reaction rather than the transition from gas to liquid phase. H₂S₍g₎ removal efficiency of >95% was recorded with Fe(III) concentration of 9 g/L using typical AFO air compositions. The 2ⁿᵈ part of the work focused on kinetics of Fe(II) oxidation by AF. A new lab technique was developed for determining the kinetic equation and kinetic parameters (KS, Kₚ and mₘₐₓ) for the bacteria. The 3ʳᵈ part focused on iron oxide precipitation under the operational conditions. It was found that at lower pH (1.5) jarosite accumulation is slower and that the performance of the AF at this pH was sufficient for successive operation of the proposed process at the H₂S fluxes predicted from AFOs. A laboratory-scale test was carried out at Purdue University on the use of the integrated system for simultaneous hydrogen sulfide removal from a H₂S bubble column filled with ferric sulfate solution and biological regeneration of ferric ions in a packed column immobilized with enriched AFbacteria. Results demonstrated the technical feasibility of the integrated system for H₂S removal and simultaneous biological regeneration of Fe(III) for potential continuous treatment of H₂S released from CAFO. NH₃ and H₂S gradient measurements at egg layer and swine barns were conducted in winter and summer at Purdue. Results showed high potential to concentrate NH₃ and H₂S in hog buildings, and NH₃ in layer houses. H₂S emissions from layer houses were too low for a significant gradient. An NH₃ capturing system was designed and tested in a 100-chicken broiler room. Five bell-type collecting devices were installed over the litter to collect NH₃ emissions. While the air extraction system moved only 10% of the total room ventilation airflow rate, the fraction of total ammonia removed was 18%, because of the higher concentration air taken from near the litter. The system demonstrated the potential to reduce emissions from broiler facilities and to concentrate the NH₃ effluent for use in an emission control system. In summary, the project laid a solid foundation for the implementation of both processes, and also resulted in a significant scientific contribution related to AF kinetic studies and ferrous analytical measurements.