Methods of celestial mechanics
Brouwer, Dirk
2013-01-01
Methods of Celestial Mechanics provides a comprehensive background of celestial mechanics for practical applications. Celestial mechanics is the branch of astronomy that is devoted to the motions of celestial bodies. This book is composed of 17 chapters, and begins with the concept of elliptic motion and its expansion. The subsequent chapters are devoted to other aspects of celestial mechanics, including gravity, numerical integration of orbit, stellar aberration, lunar theory, and celestial coordinates. Considerable chapters explore the principles and application of various mathematical metho
Frontiers in relativistic celestial mechanics
2014-01-01
Relativistic celestial mechanics – investigating the motion celestial bodies under the influence of general relativity – is a major tool of modern experimental gravitational physics. With a wide range of prominent authors from the field, this two-volume series consists of reviews on a multitude of advanced topics in the area of relativistic celestial mechanics – starting from more classical topics such as the regime of asymptotically-flat spacetime, light propagation and celestial ephemerides, but also including its role in cosmology and alternative theories of gravity as well as modern experiments in this area.
The geometry of celestial mechanics
Geiges, Hansjörg
2016-01-01
Celestial mechanics is the branch of mathematical astronomy devoted to studying the motions of celestial bodies subject to the Newtonian law of gravitation. This mathematical introductory textbook reveals that even the most basic question in celestial mechanics, the Kepler problem, leads to a cornucopia of geometric concepts: conformal and projective transformations, spherical and hyperbolic geometry, notions of curvature, and the topology of geodesic flows. For advanced undergraduate and beginning graduate students, this book explores the geometric concepts underlying celestial mechanics and is an ideal companion for introductory courses. The focus on the history of geometric ideas makes it perfect supplementary reading for students in elementary geometry and topology. Numerous exercises, historical notes and an extensive bibliography provide all the contextual information required to gain a solid grounding in celestial mechanics.
An introduction to celestial mechanics
Moulton, Forest Ray
1984-01-01
An unrivaled text in the field of celestial mechanics, Moulton's theoretical work on the prediction and interpretation of celestial phenomena has not been superseded. By providing a general account of all parts of celestial mechanics without an over-full treatment of any single aspect, by stating all the problems in advance, and, where the transformations are long, giving an outline of the steps which must be made, and by noting all the places where assumptions have been introduced or unjustified methods employed, Moulton has insured that his work will be valuable to all who are interested in
Celestial mechanics and astrodynamics theory and practice
Gurfil, Pini
2016-01-01
This volume is designed as an introductory text and reference book for graduate students, researchers and practitioners in the fields of astronomy, astrodynamics, satellite systems, space sciences and astrophysics. The purpose of the book is to emphasize the similarities between celestial mechanics and astrodynamics, and to present recent advances in these two fields so that the reader can understand the inter-relations and mutual influences. The juxtaposition of celestial mechanics and astrodynamics is a unique approach that is expected to be a refreshing attempt to discuss both the mechanics of space flight and the dynamics of celestial objects. “Celestial Mechanics and Astrodynamics: Theory and Practice” also presents the main challenges and future prospects for the two fields in an elaborate, comprehensive and rigorous manner. The book presents homogenous and fluent discussions of the key problems, rendering a portrayal of recent advances in the field together with some basic concepts and essential in...
An elementary survey of celestial mechanics
Ryabov, Y
2006-01-01
An accessible exposition of gravitation theory and celestial mechanics, this classic, oft-cited work was written by a distinguished Soviet astronomer. It explains with exceptional clarity the methods used by physicists in studying celestial phenomena.A historical introduction explains the Ptolemaic view of planetary motion and its displacement by the studies of Copernicus, Kepler, and Newton. Succeeding chapters examine the making of celestial observations and measurements and explain such central concepts as the ecliptic, the orbital plane, the two- and three-body problems, and perturbed moti
Relativistic Celestial Mechanics of the Solar System
Kopeikin, Sergei; Kaplan, George
2011-01-01
This authoritative book presents the theoretical development of gravitational physics as it applies to the dynamics of celestial bodies and the analysis of precise astronomical observations. In so doing, it fills the need for a textbook that teaches modern dynamical astronomy with a strong emphasis on the relativistic aspects of the subject produced by the curved geometry of four-dimensional spacetime. The first three chapters review the fundamental principles of celestial mechanics and of special and general relativity. This background material forms the basis for understanding relativistic r
Recent advances in celestial and space mechanics
Chyba, Monique
2016-01-01
This book presents recent advances in space and celestial mechanics, with a focus on the N-body problem and astrodynamics, and explores the development and application of computational techniques in both areas. It highlights the design of space transfers with various modes of propulsion, like solar sailing and low-thrust transfers between libration point orbits, as well as a broad range of targets and applications, like rendezvous with near Earth objects. Additionally, it includes contributions on the non-integrability properties of the collinear three- and four-body problem, and on general conditions for the existence of stable, minimum energy configurations in the full N-body problem. A valuable resource for physicists and mathematicians with research interests in celestial mechanics, astrodynamics and optimal control as applied to space transfers, as well as for professionals and companies in the industry.
Modern Celestial Mechanics: From Theory to Applications
Celletti, A.; Ferraz-Mello, S.; Henrard, J.
2002-10-01
This book is intended to diffuse original research results interesting to people working in Celestial Mechanics in both theory and applications. Theoretical investigators will find several results on Hamiltonian Dynamics, Periodic Orbits, Chaos Diagnostic and Perturbations Theory. Applications cover several directions of research starting with those related to space exploration (mission design and space research) to those related to astronomy (extrasolar planets, asteroids, Near Earth asteroids). Since this book carries original results, it is unique and complements similar books and journals. Some of the subjects have great media appeal: the risk of impact of space debris on the Space Station, the possibility of fly-by missions to asteroids approaching dangerously to our planet, the study of the orbits of these objects, etc. Appealing for a large audience among scientists are the subjects related to Chaos and Order as well as those centered on the study of the dynamics of exoplanets (extrasolar planets). The appeal of the more theoretical papers lies in the fact that they make a tour on the state-of-the-art of several classical problems. Link: http://www.wkap.nl/prod/b/1-4020-0762-0
Relativistic Celestial Mechanics of the Solar System
Kopeikin, Sergei; Efroimsky, Michael; Kaplan, George
2011-09-01
The general theory of relativity was developed by Einstein a century ago. Since then, it has become the standard theory of gravity, especially important to the fields of fundamental astronomy, astrophysics, cosmology, and experimental gravitational physics. Today, the application of general relativity is also essential for many practical purposes involving astrometry, navigation, geodesy, and time synchronization. Numerous experiments have successfully tested general relativity to a remarkable level of precision. Exploring relativistic gravity in the solar system now involves a variety of high-accuracy techniques, for example, very long baseline radio interferometry, pulsar timing, spacecraft Doppler tracking, planetary radio ranging, lunar laser ranging, the global positioning system (GPS), torsion balances and atomic clocks. Over the last few decades, various groups within the International Astronomical Union have been active in exploring the application of the general theory of relativity to the modeling and interpretation of high-accuracy astronomical observations in the solar system and beyond. A Working Group on Relativity in Celestial Mechanics and Astrometry was formed in 1994 to define and implement a relativistic theory of reference frames and time scales. This task was successfully completed with the adoption of a series of resolutions on astronomical reference systems, time scales, and Earth rotation models by the 24th General Assembly of the IAU, held in Manchester, UK, in 2000. However, these resolutions only form a framework for the practical application of relativity theory, and there have been continuing questions on the details of the proper application of relativity theory to many common astronomical problems. To ensure that these questions are properly addressed, the 26th General Assembly of the IAU, held in Prague in August 2006, established the IAU Commission 52, "Relativity in Fundamental Astronomy". The general scientific goals of the new
Frontiers in Relativistic Celestial Mechanics, Vol. 2, Applications and Experiments
Kopeikin, Sergei
2014-08-01
Relativistic celestial mechanics - investigating the motion celestial bodies under the influence of general relativity - is a major tool of modern experimental gravitational physics. With a wide range of prominent authors from the field, this two-volume series consists of reviews on a multitude of advanced topics in the area of relativistic celestial mechanics - starting from more classical topics such as the regime of asymptotically-flat spacetime, light propagation and celestial ephemerides, but also including its role in cosmology and alternative theories of gravity as well as modern experiments in this area. This second volume of a two-volume series covers applications of the theory as well as experimental verifications. From tools to determine light travel times in curved space-time to laser ranging between earth and moon and between satellites, and impacts on the definition of time scales and clock comparison techniques, a variety of effects is discussed. On the occasion of his 80-th birthday, these two volumes honor V. A. Brumberg - one of the pioneers in modern relativistic celestial mechanics. Contributions include: J. Simon, A. Fienga: Victor Brumberg and the French school of analytical celestial mechanics T. Fukushima: Elliptic functions and elliptic integrals for celestial mechanics and dynamical astronomy P. Teyssandier: New tools for determining the light travel time in static, spherically symmetric spacetimes beyond the order G2 J. Müller, L. Biskupek, F. Hofmann and E. Mai: Lunar laser ranging and relativity N. Wex: Testing relativistic celestial mechanics with radio pulsars I. Ciufolini et al.: Dragging of inertial frames, fundamental physics, and satellite laser ranging G. Petit, P. Wolf, P. Delva: Atomic time, clocks, and clock comparisons in relativistic spacetime: a review
Frontiers in Relativistic Celestial Mechanics, Vol. 1. Theory
Kopeikin, Sergei
2014-10-01
Relativistic celestial mechanics - investigating the motion celestial bodies under the influence of general relativity - is a major tool of modern experimental gravitational physics. With a wide range of prominent authors from the field, this two-volume series consists of reviews on a multitude of advanced topics in the area of relativistic celestial mechanics - starting from more classical topics such as the regime of asymptotically-flat spacetime, light propagation and celestial ephemerides, but also including its role in cosmology and alternative theories of gravity as well as modern experiments in this area. This first volume of a two-volume series is concerned with theoretical foundations such as post-Newtonian solutions to the two-body problem, light propagation through time-dependent gravitational fields, as well as cosmological effects on the movement of bodies in the solar systems. On the occasion of his 80-th birthday, these two volumes honor V. A. Brumberg - one of the pioneers in modern relativistic celestial mechanics. Contributions include: M. Soffel: On the DSX-framework T. Damour: The general relativistic two body problem G. Schaefer: Hamiltonian dynamics of spinning compact binaries through high post-Newtonian approximations A. Petrov and S. Kopeikin: Post-Newtonian approximations in cosmology T. Futamase: On the backreaction problem in cosmology Y. Xie and S. Kopeikin: Covariant theory of the post-Newtonian equations of motion of extended bodies S. Kopeikin and P. Korobkov: General relativistic theory of light propagation in multipolar gravitational fields
5th Austrian Hungarian workshop on celestial mechanics
Süli, Áron
2011-06-01
The 5th Hungarian-Austrian Workshop on Celestial Mechanics took place from 9th until the 10th of April 2010 in Vienna, Austria. The workshop was held in the Institute for Astronomy of Vienna University. From the Eötvös University and from the host institute experts and PhD students gathered together to discuss the challenges and new results of the actual problems of celestial mechanics. The workshop was held in the meeting room at the Sternwarte of the Vienna University located in a magnificent park in the heart of Vienna. Following the themes of the four previous events the focus for this workshop ranged from the Trojan problem, dynamics in binary star systems and exoplanetray systems. We were pleased to acknowledge the support of the host university. The talks were characterized by a large spectrum, which is typical of the workshops on celestial mechanics. Several talks discussed different aspects of the trojan problem, such as the three Trojan Problem, dynamics of trojan-like planets in binary stars, the frequencies of their motion around the triangular lagrangian points, etc. Several speakers focused on the formation of planetary systems and on the field of exoplanetary systems, like exoplanetary systems in higher order mean motion resonances, formation of planets in binary systems, stability of exomoons etc. Some of the presentation used sophisticated mathematical tools in order to understand mean motion resonances, the Sitnikov problem applying the KAM and the Nekhoroshev theorem. The theme of a number of talks was the motion of Solar System bodies: dynamics of the newly discovered moons of Pluto and of near-Earth asteroids. General problems were also addressed, among others chaos in Hamiltonian systems, adaptive Lie-integration method and iterative solution approximation to the generalised Sitnikov problem.
TRIP: General computer algebra system for celestial mechanics
Laskar, J.; Gastineau, M.
2012-10-01
TRIP is an interactive computer algebra system that is devoted to perturbation series computations, and specially adapted to celestial mechanics. Its development started in 1988, as an upgrade of the special purpose FORTRAN routines elaborated by J. Laskar for the demonstration of the chaotic behavior of the Solar System. TRIP is a mature and efficient tool for handling multivariate generalized power series, and embeds two kernels, a symbolic and a numerical kernel. This numerical kernel communicates with Gnuplot or Grace to plot the graphics and allows one to plot the numerical evaluation of symbolic objects.
Kepler-16 Circumbinary System Validates Quantum Celestial Mechanics
Directory of Open Access Journals (Sweden)
Potter F.
2012-01-01
Full Text Available We report the application of quantum celestial mechanics (QCM to the Kepler-16 cir- cumbinary system which has a single planet orbiting binary stars with the important system parameters known to within one percent. Other gravitationally bound systems such as the Solar System of planets and the Jovian satellite systems have large uncertain- ties in their total angular momentum. Therefore, Kepler-16 allows us for the first time to determine whether the QCM predicted angular momentum per mass quantization is valid.
An approach to Mel'nikov theory in celestial mechanics
Cicogna, G
1999-01-01
Using a completely analytic procedure - based on a suitable extension of a classical method - we discuss an approach to the Poincaré-Mel'nikov theory, which can be conveniently applied also to the case of non-hyperbolic critical points, and even if the critical point is located at the infinity. In this paper, we concentrate our attention on the latter case, and precisely on problems described by Kepler-like potentials in one or two degrees of freedom, in the presence of general time-dependent perturbations. We show that the appearance of chaos (possibly including Arnol'd diffusion) can be proved quite easily and in a direct way, without resorting to singular coordinate transformations, such as the McGehee or blowing-up transformations. Natural examples are provided by the classical Gyldén problem, originally proposed in celestial mechanics, but also of interest in different fields, and by the general 3-body problem in classical mechanics.
A new method of single celestial-body sun positioning based on theory of mechanisms
Institute of Scientific and Technical Information of China (English)
Zhang Wei; Xu Xiaofeng; Wu Yuanzhe
2016-01-01
Considering defects of current single celestial-body positioning methods such as discon-tinuity and long period, a new sun positioning algorithm is herein put forward. Instead of tradi-tional astronomical spherical trigonometry and celestial coordinate system, the proposed new positioning algorithm is built by theory of mechanisms. Based on previously derived solar vector equations (from a C1R2P2 series mechanism), a further global positioning method is developed by inverse kinematics. The longitude and latitude coordinates expressed by Greenwich mean time (GMT) and solar vector in local coordinate system are formulated. Meanwhile, elimination method of multiple solutions, errors of longitude and latitude calculation are given. In addition, this algo-rithm has been integrated successfully into a mobile phone application to visualize sun positioning process. Results of theoretical verification and smart phone’s test demonstrate the validity of pre-sented coordinate’s expressions. Precision is shown as equivalent to current works and is acceptable to civil aviation requirement. This new method solves long-period problem in sun sight running fix-ing and improves applicability of sun positioning. Its methodology can inspire development of new sun positioning device. It would be more applicable to be combined with inertial navigation systems for overcoming discontinuity of celestial navigation systems and accumulative errors of inertial nav-igation systems.
Status of GRAIL Gravity Field Determination Using the Celestial Mechanics Approach
Arnold, Daniel; Beutler, Gerhard; Jäggi, Adrian; Bock, Heike; Mervart, Leos; Meyer, Ulrich; Bertone, Stefano
To determine the gravity field of the Moon, the NASA mission GRAIL (Gravity Recovery And Interior Laboratory) inherits its concept from the Earth orbiting GRACE (Gravity Recovery and Climate Experiment) mission. The use of ultra-precise inter-satellite Ka-band ranging observations enables data acquisition even when the spacecraft are not tracked from the Earth. The data allows for a highly accurate estimation of the lunar gravity field with unprecedented resolution on both sides of the Moon, which is crucial to improve the understanding of its internal structure and thermal evolution. In this presentation we discuss GRAIL-based lunar gravity fields generated with the Celestial Mechanics Approach. Ka-band range-rate (KBRR) observations and position data (GNI1B products) are used to solve for the lunar gravity field parameters in a generalized orbit determination problem. Apart from normalized spherical harmonic coefficients up to degrees n≤ 200, also arc- and satellite-specific parameters, like initial state vectors and pseudo-stochastic pulses, are set up as common parameters for all measurement types. The latter shall compensate for imperfect models of non-gravitational accelerations, e.g., caused by solar radiation pressure. In addition, especially for the data of the primary mission phase, it is essential to estimate time bias parameters for the KBRR observations. We compare our results from the nominal mission phase with the official Level 2 gravity field models first released in October 2013. Our results demonstrate that the lunar gravity field can be recovered with a high quality by adapting the Celestial Mechanics Approach, even when using pre-GRAIL or pre-SELENE gravity field models as a priori fields and when replacing sophisticated models of non-gravitational accelerations by appropriately spaced and constrained pseudo-stochastic pulses. Yet, the usage of preprocessed position data as pseudo observations is not fully satisfying and is potentially
Celletti, A
2006-01-01
The book provides the most recent advances of Celestial Mechanics, as provided by high-level scientists working in this field. It covers theoretical investigations as well as applications to concrete problems. Outstanding review papers are included in the book and they introduce the reader to leading subjects, like the variational approaches to find periodic orbits, the stability theory of the N-body problem, the spin-orbit resonances and chaotic dynamics, the space debris polluting the circumterrestrial space.
Cors, Josep; Llibre, Jaume; Korobeinikov, Andrei
2015-01-01
The two parts of the present volume contain extended conference abstracts corresponding to selected talks given by participants at the "Conference on Hamiltonian Systems and Celestial Mechanics 2014" (HAMSYS2014) (15 abstracts) and at the "Workshop on Virus Dynamics and Evolution" (12 abstracts), both held at the Centre de Recerca Matemàtica (CRM) in Barcelona from June 2nd to 6th, 2014, and from June 23th to 27th, 2014, respectively. Most of them are brief articles, containing preliminary presentations of new results not yet published in regular research journals. The articles are the result of a direct collaboration between active researchers in the area after working in a dynamic and productive atmosphere. The first part is about Central Configurations, Periodic Orbits and Hamiltonian Systems with applications to Celestial Mechanics – a very modern and active field of research. The second part is dedicated to mathematical methods applied to viral dynamics and evolution. Mathematical modelling of biologi...
Directory of Open Access Journals (Sweden)
Potter F.
2014-01-01
Full Text Available The Kepler-47 circumbinary system has three known planets orbiting its binary star barycenter and therefore can provide a precision test of the Quantum Celestial Mechan- ics (QCM prediction of the quantization of angular momentum per unit mass in all gravitationally bound systems. Two of the planets are in the Habitable Zone (HZ, so system stability can be a primary concern. QCM may be a major contributor to the stability of this system.
Barkin, Yu. V.; Ferrandiz, J. M.
2003-04-01
In given report we discuss tidal and non-tidal mechanisms of forced tectonic (endogenous) activity of the Earth caused by gravitational attraction of the Moon, Sun and the planets. On the base of the classical solution of the problem of elasticity for model of the Earth with concentric mass distribution the evaluations of the tidal energy and power of Earth lunar-solar deformations, including their joint effect, were obtained. Important role of the joint energetic effect of rotational deformation of the Earth with lunar and solar tides was illustrated. Gravitational interaction of the Moon and Sun with non-spherical, non-homogeneous shells of the Earth generates big additional mechanical forces and moments of the interaction of the neighboring shells (rigid core, liquid core, mantle, lithosphere and separate plates). Acting of these forces and moments in the different time scales on the corresponding sells generates cyclic perturbations of the tensional state of the shells, their deformations, small relative translational displacements and small relative rotational oscillations of the shells. In geological period of time it leads to a fundamental tectonic reconstruction of the Earth. These additional forces and moments of the cyclic celestial-mechanical nature produce cyclic deformations of the all layers of the body and organize and control practically all natural processes. The additional force between mantle and core is cyclic and characterized by the wide basis of frequencies typical for orbital motions (of the Sun, Moon and planets), for rotational motion of the Earth, Moon and Sun and for many from observed natural processes. The problem about small relative translatory-rotary motion of the two shells separated by the thin viscous-elastic layer is studied. The differential equations of motion were obtained and have been studied in particular cases (plane motion of system; case of two axisymmetrical interacting shells and oth.) by approximate methods of small
Lachièze-Rey, Marc; Luminet, Jean-Pierre
2001-07-01
Throughout history, the mysterious dark skies have inspired our imaginations in countless ways, influencing our endeavors in science and philosophy, religion, literature, and art. Filled with 380 full-color illustrations, Celestial Treasury shows the influence of astronomical theories and the richness of illustrations in Western civilization through the ages. The authors explore the evolution of our understanding of astronomy and weave together ancient and modern theories in a fascinating narrative. They incorporate a wealth of detail from Greek verse, medieval manuscripts and Victorian poetry with contemporary spacecraft photographs and computer-generated star charts. Celestial Treasury is more than a beautiful book: it answers a variety of questions that have intrigued scientists and laymen for centuries. -- How did philosophers and scientists try to explain the order that governs celestial motion? -- How did geometers and artists measure and map the skies? -- How many different answers have been proposed for the most fundamental of all questions: When and how did Earth come about? -- Who inhabits the heavens--gods, angels or extraterrestrials? No other book recounts humankind's fascination with the heavens as compellingly as Celestial Treasury. Marc Lachièze-Rey is a director of research at the Centre National pour la Récherche Scientifique and astrophysicist at the Centre d'Etudes de Saclay. He is the author of The Cosmic Background Radiation (Cambridge, 1999), and and The Quest for Unity, (Oxford, 1999 ), as well as many books in French. Jean-Pierre Luminet is a research director of the Centre National pour la Rechérche Scientifique, based at the Paris-Meudon observatory. He is the author of Black Holes, (Cambridge 1992), as well as science documentaries for television.
Érdi, B.; Szenkovits, F.
2007-05-01
In 25--27 May 2006 an International Conference on Actual Problems in Celestial Mechanics and Dynamical Astronomy was organized at Cluj-Napoca. The Faculty of Mathematics and Computer Science of the Babeş-Bolyai University, the host of this conference, organized this scientific meeting in collaboration with the Loránd Eötvös University (Budapest, Hungary), Sapientia University (Miercuria Ciuc, Romania), Astronomical Institute of the Romanian Academy (Bucharest, Romania) and Institute for Space Science (Bucharest, Romania). The main topics covered by the meeting were: - Solar-System dynamics, stability, resonances, chaos; - Dynamics of populations in the Solar System: NEAs, MBAs, Centaurs, KBOs, TNOs: observations, orbits, theoretical models; - Galactic and extragalactic dynamics; - Problems, models, methods and techniques in contemporary celestial mechanics and dynamical astronomy. The conference was structured into seven sessions of oral presentations, a poster session and a round table discussion. Each of the seven main sessions began with an invited lecture. These lectures reviewed the following fields: the Sitnikov problem (R. Dvorak, Austria); the age of the asteroid families (Z. Knezevic, Serbia and Montenegro); stability of exoplanetary systems (B. Érdi, Hungary); Saari's conjecture (Diacu, Canada); integrability from direct and inverse standpoints (G. Bozis, Greece); stability of exact solutions in restricted many-body problems (E. Grebenicov, Russia); actual Romanian research in post-Newtonian dynamics (V. Mioc, Romania). Beside the invited lectures, the 21 oral presentations covered the most various domains of celestial mechanics and dynamical astronomy. Chaotic behaviour was a premier topic. It was approached and studied by analytical, geometrical and numerical methods in many astronomical problems: the restricted three-body problem (with examples in the Solar System), the Gylden's model and its generalizations, capture domain, resonances, etc
Vozmishcheva, Tatiana
2016-09-01
The connection between the problems of celestial mechanics: the Kepler problem, the two-center problem and the two body problem in spaces of constant curvature with the generalized Kepler and Hooke potentials is investigated. The limit passage in the two-center and two body problems in the Lobachevsky space and on a sphere is carried out as λto0 (λ is the curvature of the corresponding space) for the two potentials. The potentials and metrics in spaces under study are written in the gnomonic coordinates. It is shown that as the curvature radius tends to infinity, the generalized gravitational and elastic potentials transform to the Kepler and Hooke forms in the Euclidean space.
On the Analysis of Multistep-Out-of-Grid Method for Celestial Mechanics Tasks
Olifer, L.; Choliy, V.
2016-09-01
Occasionally, there is a necessity in high-accurate prediction of celestial body trajectory. The most common way to do that is to solve Kepler's equation analytically or to use Runge-Kutta or Adams integrators to solve equation of motion numerically. For low-orbit satellites, there is a critical need in accounting geopotential and another forces which influence motion. As the result, the right side of equation of motion becomes much bigger, and classical integrators will not be quite effective. On the other hand, there is a multistep-out-of-grid (MOG) method which combines Runge-Kutta and Adams methods. The MOG method is based on using m on-grid values of the solution and n × m off-grid derivative estimations. Such method could provide stable integrators of maximum possible order, O (hm+mn+n-1). The main subject of this research was to implement and analyze the MOG method for solving satellite equation of motion with taking into account Earth geopotential model (ex. EGM2008 (Pavlis at al., 2008)) and with possibility to add other perturbations such as atmospheric drag or solar radiation pressure. Simulations were made for satellites on low orbit and with various eccentricities (from 0.1 to 0.9). Results of the MOG integrator were compared with results of Runge-Kutta and Adams integrators. It was shown that the MOG method has better accuracy than classical ones of the same order and less right-hand value estimations when is working on high orders. That gives it some advantage over "classical" methods.
Burnham, Robert
1978-01-01
Volume II of a comprehensive three-part guide to celestial objects outside our solar system ranges from Chamaeleon to Orion. Features coordinates, classifications, physical descriptions, hundreds of visual aids. 1977 edition.
Burnham, Robert
1978-01-01
Volume I of this comprehensive three-part guide to the thousands of celestial objects outside our solar system ranges from Andromeda through Cetus. Objects are grouped according to constellation, and their definitions feature names, coordinates, classifications, and physical descriptions. Additional notes offer fascinating historical information. Hundreds of visual aids. 1977 edition.
Burnham, Robert
1978-01-01
Volume III of this three-part comprehensive guide to the thousands of celestial objects outside our solar system concludes with listings from Pavo through Vulpecula. Objects are grouped according to constellation, and their definitions feature names, coordinates, classifications, and physical descriptions. Additional notes offer fascinating historical information. Hundreds of visual aids. 1977 edition.
Knudsen, Steven; Golubovic, Leonardo
Prospects to build Space Elevator (SE) systems have become realistic with ultra-strong materials such as carbon nano-tubes and diamond nano-threads. At cosmic length-scales, space elevators can be modeled as polymer like floppy strings of tethered mass beads. A new venue in SE science has emerged with the introduction of the Rotating Space Elevator (RSE) concept supported by novel algorithms discussed in this presentation. An RSE is a loopy string reaching into outer space. Unlike the classical geostationary SE concepts of Tsiolkovsky, Artsutanov, and Pearson, our RSE exhibits an internal rotation. Thanks to this, objects sliding along the RSE loop spontaneously oscillate between two turning points, one of which is close to the Earth whereas the other one is in outer space. The RSE concept thus solves a major problem in SE technology which is how to supply energy to the climbers moving along space elevator strings. The investigation of the classical and statistical mechanics of a floppy string interacting with objects sliding along it required development of subtle computational algorithms described in this presentation
Center of Mass of Two or More Celestial Bodies as a Basis of Comets and «Black Holes» Mechanism
Eugeny F. Orlov
2012-01-01
The article considers the questions, arising during rendezvous of two celestial bodies with equal mass, one of which is the Earth and the consequences of such rendezvous to modern civilization, suggests the idea of centers of galaxies mass with anomalously large values of the gravitational fields, which allows to divide them into two types – material filled and hollow.
Center of Mass of Two or More Celestial Bodies as a Basis of Comets and «Black Holes» Mechanism
Directory of Open Access Journals (Sweden)
Eugeny F. Orlov
2012-04-01
Full Text Available The article considers the questions, arising during rendezvous of two celestial bodies with equal mass, one of which is the Earth and the consequences of such rendezvous to modern civilization, suggests the idea of centers of galaxies mass with anomalously large values of the gravitational fields, which allows to divide them into two types – material filled and hollow.
Saari's Conjecture in Celestial Mechanics
Diacu, Florin; Fujiwara, Toshiaki; Pérez-Chavela, Ernesto; Santoprete, Manuele
2008-09-01
In 1969, D. Saari conjectured that the only solutions of the Newtonian n-body problem that have constant moment of inertia are relative equilibria. For n = 3, there is a computer assisted proof of this conjecture given by R. Moeckel in 2005, [10]. The collinear case was solved the same year by F. Diacu, E. Pérez-Chavela, and M. Santoprete, [4], All the other cases are open. Denoting by U the potential energy, Saari's homographic conjecture states that if along an orbit of the n-body problem IU2 is constant, then the orbit is a homographic solution, i.e. a solution whose initial configuration remains similar to itself. In this paper, we discuss both conjectures and survey the proof of the latter for a large set of initial data. This survey follows our previous paper on this subject, [5].
KAM Stability and Celestial Mechanics
Celletti, A
2004-01-01
KAM theory is a powerful tool apt to prove perpetual stability in Hamiltonian systems, which are a perturbation of integrable ones. The smallness requirements for its applicability are well known to be extremely stringent. A long standing problem, in this context, is the application of KAM theory to ``physical systems" for ``observable" values of the perturbation parameters. Here, we consider the Restricted, Circular, Planar, Three-Body Problem (RCPTBP),i.e., the problem of studying the planar motions of a small body subject to the gravitational attraction of two primary bodies revolving on circular Keplerian orbits (which are assumed not to be influenced by the small body). When the mass ratio of the two primary bodies is small the RCPTBP is described by a nearly-integrable Hamiltonian system with two degrees of freedom; in a region of phase space corresponding to nearly elliptical motions with non small eccentricities, the system is well described by Delaunay variables. The Sun-Jupiter observed motion is ne...
Celestial data routing network
Bordetsky, Alex
2000-11-01
Imagine that information processing human-machine network is threatened in a particular part of the world. Suppose that an anticipated threat of physical attacks could lead to disruption of telecommunications network management infrastructure and access capabilities for small geographically distributed groups engaged in collaborative operations. Suppose that small group of astronauts are exploring the solar planet and need to quickly configure orbital information network to support their collaborative work and local communications. The critical need in both scenarios would be a set of low-cost means of small team celestial networking. To the geographically distributed mobile collaborating groups such means would allow to maintain collaborative multipoint work, set up orbital local area network, and provide orbital intranet communications. This would be accomplished by dynamically assembling the network enabling infrastructure of the small satellite based router, satellite based Codec, and set of satellite based intelligent management agents. Cooperating single function pico satellites, acting as agents and personal switching devices together would represent self-organizing intelligent orbital network of cooperating mobile management nodes. Cooperative behavior of the pico satellite based agents would be achieved by comprising a small orbital artificial neural network capable of learning and restructing the networking resources in response to the anticipated threat.
The Celestial Basis of Civilization
Masse, W. B.
Scholars have long puzzled over the reasons for the ubiquity of celestial images in the residue of the world's earliest civilizations: in art, myth, religious cosmology, iconography, cosmogony, eschatological beliefs, and as portents for the conduct of royal and chiefly power. The general consensus is that these images represented a need by early societies to use the fixed celestial heavens in order to regulate ritual and agricultural cycles, and to satisfy a psychological need by people to relate themselves to their surrounding Universe. Such explanations are facile and miss an important aspect of the celestial heavens. The fixed celestial heavens served as the back-drop for a large number of often spectacular temporary naked-eye visible celestial events which animated the night and sometimes the daytime sky, and which created an 'otherworld' for virtually all cultural groups. In this paper I present a model derived from the detailed analysis of Hawaiian oral traditions and culture history in relation to historic astronomical records of temporary celestial events, and then apply this model to cultural traditions from Mesoamerica and other geographic regions in order to demonstrate that novae, supernovae, variable stars, comets, great meteor showers, aurorae, solar and lunar eclipses, and impacting Solar System debris, together played a critical role in the artistic, intellectual, and political development of early civilizations. These data not only provide important insights into the development of civilization, but also provide important details and longitudinal records of astronomical events and phenomena which are otherwise not readily available for scientific scrutiny.
Celestial navigation in a nutshell
Schlereth, Hewitt
2000-01-01
Celestial Navigation in a Nutshell demonstrates how to take sights by the sun, moon, stars, and planets, discussing the advantages and disadvantages of each method. The reader is taken carefully through several examples and situational illustrations, making this a most effective self-teaching guide. Common errors are reviewed and several tips on how to improve accuracy are given.
Observation of Celestial Phenomena in Ancient China
Sun, Xiaochun
Because of the need for calendar-making and portent astrology, the Chinese were diligent and meticulous observers of celestial phenomena. China has maintained the longest continuous historical records of celestial phenomena in the world. Extraordinary or abnormal celestial events were particularly noted because of their astrological significance. The historical records cover various types of celestial phenomena, which include solar and lunar eclipses, sunspots, "guest stars" (novae or supernovae as we understand today), comets and meteors, and all kinds of planetary phenomena. These records provide valuable historical data for astronomical studies today.
Celestial Navigation for the Novice
Sadler, Philip M.
2011-01-01
What kinds of astronomical lab activities can introductory astronomy students carry out easily in daytime? The most impressive is the determination of their latitude and longitude from observations of the sun. The "shooting of a noon sight” and its "reduction to a position” is a technique still practiced by navigators in this age of GPS. Indeed, the U.S. Coast Guard exams for ocean-going licenses and include celestial navigation. These techniques continue to be used by the military and by private sailors as a backup to electronic navigation systems. We present a method to establish one's latitude and longitude to better than 30 miles from measurements of the sun's altitude that is easily within the capability non-science majors. This is a practical application of astronomy in use the world over. The streamlined method used is based on an easy-to-build protractor and string quadrant. Participants will leave with all materials to conduct this activity in their own classroom.
Connecting VLBI and Gaia celestial reference frames
Malkin, Zinovy
2016-01-01
The current state of the link problem between radio and optical celestial reference frames is considered. The main objectives of the investigations in this direction during the next few years are the preparation of a comparison and the mutual orientation and rotation between the optical {\\it Gaia} Celestial Reference Frame (GCRF) and the 3rd generation radio International Celestial Reference Frame (ICRF3), obtained from VLBI observations. Both systems, ideally, should be a realization of the ICRS (International Celestial Reference System) at micro-arcsecond level accuracy. Therefore, the link accuracy between the ICRF and GCRF should be obtained with similar error level, which is not a trivial task due to relatively large systematic and random errors in source positions at different frequency bands. In this paper, a brief overview of recent work on the GCRF--ICRF link is presented. Additional possibilities to improve the GCRF--ICRF link accuracy are discussed. The suggestion is made to use astrometric radio s...
The stratification of regolith on celestial objects
Schräpler, Rainer; von Borstel, Ingo; Güttler, Carsten
2015-01-01
All atmosphere-less planetary bodies are covered with a dust layer, the so-called regolith, which determines the optical, mechanical and thermal properties of their surface. These properties depend on the regolith material, the size distribution of the particles it consists of, and the porosity to which these particles are packed. We performed experiments in parabolic flights to determine the gravity dependency of the packing density of regolith for solid-particle sizes of 60 $\\mu$m and 1 mm as well as for 100-250 $\\mu$m-sized agglomerates of 1.5 $\\mu$m-sized solid grains. We utilized g-levels between 0.7 m s$^{-2}$ and 18 m s$^{-2}$ and completed our measurements with experiments under normal gravity conditions. Based on previous experimental and theoretical literature and supported by our new experiments, we developed an analytical model to calculate the regolith stratification of celestial rocky and icy bodies and estimated the mechanical yields of the regolith under the weight of an astronaut and a spacec...
Celestial Mechanics, Conformal Structures, and Gravitational Waves
Duval, C; Horvathy, P
1991-01-01
The equations of motion for $N$ non-relativistic particles attracting according to Newton's law are shown to correspond to the equations for null geodesics in a $(3N+2)$-dimensional Lorentzian, Ricci-flat, spacetime with a covariantly constant null vector. Such a spacetime admits a Bargmann structure and corresponds physically to a generalized pp-wave. Bargmann electromagnetism in five dimensions comprises the two Galilean electro-magnetic theories (Le Bellac and L\\'evy-Leblond). At the quantum level, the $N$-body Schr\\"odinger equation retains the form of a massless wave equation. We exploit the conformal symmetries of such spacetimes to discuss some properties of the Newtonian $N$-body problem: homographic solutions, the virial theorem, Kepler's third law, the Lagrange-Laplace-Runge-Lenz vector arising from three conformal Killing 2-tensors, and motions under inverse square law forces with a gravitational constant $G(t)$ varying inversely as time (Dirac). The latter problem is reduced to one with time indep...
Celestial mechanics of elastic bodies II
Beig, Robert; Schmidt, Bernd G
2016-01-01
We construct time independent configurations describing a small elastic body moving in a circular orbit in the Schwarzschild spacetime. These configurations are relativistic versions of Newtonian solutions constructed by two of us (R.B.,B.G.S.). In the process we simplify and sharpen previous results of ours concerning elastic bodies in rigid rotation.
Connecting VLBI and Gaia celestial reference frames
Directory of Open Access Journals (Sweden)
Zinovy Malkin
2016-09-01
Full Text Available The current state of the link problem between radio and optical celestial reference frames is considered.The main objectives of the investigations in this direction during the next few years are the preparation of a comparisonand the mutual orientation and rotation between the optical it Gaia Celestial Reference Frame (GCRFand the 3rd generation radio International Celestial Reference Frame (ICRF3, obtained from VLBI observations.Both systems, ideally, should be a realization of the ICRS (International Celestial Reference System at micro-arcsecond level accuracy.Therefore, the link accuracy between the ICRF and GCRF should be obtained with similar error level, which is not a trivial taskdue to relatively large systematic and random errors in source positions at different frequency bands.In this paper, a brief overview of recent work on the GCRF--ICRF link is presented.Additional possibilities to improve the GCRF--ICRF link accuracy are discussed.The suggestion is made to use astrometric radio sources with optical magnitude to 20$^m$ rather than to 18$^m$ as currently plannedfor the GCRF--ICRF link.In addition, the use of radio stars is also a prospective method to obtain independent and accurate orientation between the Gaia frame and the ICRF.
Orbital behavior around a nonuniform celestial body
Rosson, Z.; Hall, F.; Vogel, T.
2016-09-01
To effectively model the orbit around a nonuniform celestial body, detailed information needs to be determined of the perturbations. This research looked at one of the most crucial perturbations: the nonuniform gravitational field of a celestial body. Given an orbiting particle (a satellite), we utilized numerical methods to calculate its orbit in two dimensions around a discretized center mass structure. The gravitational acceleration imposed on the particle due to each mass point sums vectorally as the particle completes each infinitesimal time step of one orbit. There are noticeable effects on the orbit as the conditions of the center mass change. The development of a simulation code allows for the modelling of the orbit about an irregular body with satisfactory accuracy.
Magnetic information calibrates celestial cues during migration.
Sandberg; Bäckman; Moore; Lõhmus
2000-10-01
Migratory birds use celestial and geomagnetic directional information to orient on their way between breeding and wintering areas. Cue-conflict experiments involving these two orientation cue systems have shown that directional information can be transferred from one system to the other by calibration. We designed experiments with four species of North American songbirds to: (1) examine whether these species calibrate orientation information from one system to the other; and (2) determine whether there are species-specific differences in calibration. Migratory orientation was recorded with two different techniques, cage tests and free-flight release tests, during autumn migration. Cage tests at dusk in the local geomagnetic field revealed species-specific differences: red-eyed vireo, Vireo olivaceus, and northern waterthrush, Seiurus noveboracensis, selected seasonally appropriate southerly directions whereas indigo bunting, Passerina cyanea, and grey catbird, Dumetella carolinensis, oriented towards the sunset direction. When tested in deflected magnetic fields, vireos and waterthrushes responded by shifting their orientation according to the deflection of the magnetic field, but buntings and catbirds failed to show any response to the treatment. In release tests, all four species showed that they had recalibrated their star compass on the basis of the magnetic field they had just experienced in the cage tests. Since release tests were done in the local geomagnetic field it seems clear that once the migratory direction is determined, most likely during the twilight period, the birds use their recalibrated star compass for orientation at departure. Copyright 2000 The Association for the Study of Animal Behaviour.
Celestial shadows eclipses, transits, and occultations
Westfall, John
2015-01-01
Much of what is known about the universe comes from the study of celestial shadows—eclipses, transits, and occultations. The most dramatic are total eclipses of the Sun, which constitute one of the most dramatic and awe-inspiring events of nature. Though once a source of consternation or dread, solar eclipses now lead thousands of amateur astronomers and eclipse-chasers to travel to remote points on the globe to savor their beauty and the adrenaline-rush of experiencing totality, and were long the only source of information about the hauntingly beautiful chromosphere and corona of the Sun. Long before Columbus, the curved shadow of the Earth on the Moon during a lunar eclipse revealed that we inhabit a round world. The rare and wonderful transits of Venus, which occur as it passes between the Earth and the Sun, inspired eighteenth century expeditions to measure the distance from the Earth to the Sun, while the recent transits of 2004 and 2012 were the most widely observed ever--and still produced re...
Industrial Scale Production of Celestial Body Simulants Project
National Aeronautics and Space Administration — The technical objectives of this program are to develop a cost-effective process to deliver Celestial body simulants for the foreseeable future. Specifically, the...
A Review of Celestial Burying Ground in Tibet
Institute of Scientific and Technical Information of China (English)
YUQIAN
2005-01-01
Celestial burying ground ,also called “Mandala”,is where life leaves and comes.A huge piece of stone hidden in high mountains is surrounded by burning plants that give up smoke going up into the air.
Daytime Celestial Navigation for the Novice
Sadler, Philip M.; Night, Christopher
2010-03-01
What kinds of astronomical lab activities can high school and college astronomy students carry out easily in daytime? The most impressive is the determination of latitude and longitude from observations of the Sun. The ``shooting of a noon sight'' and its ``reduction to a position'' grew to become a daily practice at the start of the 19th century1 following the perfection of the marine chronometer by John Harrison and its mass production.2 This technique is still practiced by navigators in this age of GPS. Indeed, the U.S. Coast Guard exams for ocean-going licenses include celestial navigation.3 These techniques continue to be used by the military and by private sailors as a backup to all-too-fallible and jammable electronic navigation systems. A sextant, a nautical almanac,4 special sight reduction tables,5 and involved calculations are needed to determine position to the nearest mile using the Sun, Moon, stars, or planets. Yet, finding latitude and longitude to better than 30 miles from measurements of the Sun's altitude is easily within the capability of those taking astronomy or physics for the first time by applying certain basic principles. Moreover, it shows a practical application of astronomy in use the world over. The streamlined method described here takes advantage of the similar level of accuracy of its three components: 1.Observations using a homemade quadrant6 (instead of a sextant), 2. Student-made graphs of the altitude of the Sun over a day7 (replacing lengthy calculation using sight reduction tables), and 3. An averaged 20-year analemma used to find the Sun's navigational coordinates8,9 (rather than the 300+ page Nautical Almanac updated yearly).
Dynamical Configurations of Celestial Systems Comprised of Multiple Irregular Bodies
Jiang, Yu; Baoyin, Hexi; Li, Junfeng
2016-01-01
This manuscript considers the main features of the nonlinear dynamics of multiple irregular celestial body systems. The gravitational potential, static electric potential, and magnetic potential are considered. Based on the three established potentials, we show that three conservative values exist for this system, including a Jacobi integral. The equilibrium conditions for the system are derived and their stability analyzed. The equilibrium conditions of a celestial system comprised of n irregular bodies are reduced to 12n minus 9 equations. The dynamical results are applied to simulate the motion of multiple-asteroid systems. The simulation is useful for the study of the stability of multiple irregular celestial body systems and for the design of spacecraft orbits to triple asteroid systems discovered in the solar system. The dynamical configurations of the five triple-asteroid systems 45 Eugenia, 87 Sylvia, 93 Minerva, 216 Kleopatra, and 136617 1994CC, and the six-body system 134340 Pluto are calculated and...
Project Vesta: A Laboratory Exercise on the Measurement of Celestial Coordinates
Laird, David E.
1974-01-01
Described is an activity that was developed to measure celestial coordinates. Pictures were taken of the asteroid Vesta, coordinates for reference stars determined, and then celestial coordinates of Vesta were determined with assistance of a computer. (RH)
Post-Newtonian celestial mechanics in scalar-tensor cosmology
Galiautdinov, Andrei; Kopeikin, Sergei M.
2016-08-01
Applying the recently developed dynamical perturbation formalism on cosmological background to scalar-tensor theory, we provide a solid theoretical basis and a rigorous justification for phenomenological models of orbital dynamics that are currently used to interpret experimental measurements of the time-dependent gravitational constant. We derive the field equations for the scalar-tensor perturbations and study their gauge freedom associated with the cosmological expansion. We find a new gauge eliminating a prohibitive number of gauge modes in the field equations and significantly simplifying post-Newtonian equations of motion for localized astronomical systems in the universe with a time-dependent gravitational constant. We identify several new post-Newtonian terms and calculate their effect on secular cosmological evolution of the osculating orbital elements.
Post-Newtonian celestial mechanics in scalar-tensor cosmology
Galiautdinov, Andrei
2016-01-01
Applying the recently developed dynamical perturbation formalism on cosmological background to scalar-tensor theory, we provide a solid theoretical basis and a rigorous justification for phenomenological models of orbital dynamics that are currently used to interpret experimental measurements of the time-dependent gravitational constant. We derive the field equations for the scalar-tensor perturbations and study their gauge freedom associated with the cosmological expansion. We find a new gauge eliminating a prohibitive number of gauge modes in the field equations and significantly simplifying post-Newtonian equations of motion for localized astronomical systems in the universe with time-dependent gravitational constant. We find several new post-Newtonian terms and calculate their effect on secular cosmological evolution of the osculating orbital elements.
Physics of Planetary Rings. Celestial Mechanics of Continuous Media.
Fridman, Alexei M., Gorkavyi, Nikolai N.
Physics of Planetary Rings describes striking structures of the planetary rings of Saturn, Uranus, Jupiter, and Neptune: Narrow ringlets, spiral waves, and a chain of clumps. The author has contributed essential ideas to the full understanding of planetary rings via the stability analysis of dynamical systems. The combination of a high-quality description, the set of interesting illustrations, as well as the fascinating and natural presentation will make this book of considerable interest to astronomers, physicists, and mathematicians as well as students. There is no competing text for this book so far.
AN INTRODUCTION TO ASTROMETRY AND CELESTIAL MECHANICS: A PROPOSED SYLLABUS
Directory of Open Access Journals (Sweden)
William van Altena
2008-01-01
Full Text Available Si hemos de aprovechar la astrometría con precisión de micro segundos de arco que nos ofrecerán las nuevas técnicas de observación, debemos reformular nuestros estudios sobre sistemas de referencia y ecuaciones de movimiento en el contexto de la relatividad especial y general. También debemos desarrollar métodos más avanzados para el análisis estadístico de los datos y para la calibración de los instrumentos. En consecuencia, tenemos que revisar drásticamente los planes de estudio para adecuarlos a las necesidades de los estudiantes del siglo 21. Para ello, hemos desarrollado el programa de estudios para un curso introductorio de un semestre en Astrometría y Mecánica Celeste. El curso proporciona una introducción moderna y amplia a casi todos los temas de nuestro campo, y forma una base de conocimientos a partir de la cual el estudiante podrá elegir áreas para el estudio individual o para seguir cursos avanzados en centros especializados.
Viscoelastic tides: models for use in Celestial Mechanics
Ragazzo, C.; Ruiz, L. S.
2016-11-01
This paper contains equations for the motion of linear viscoelastic bodies interacting under gravity. The equations are fully three dimensional and allow for the integration of the spin, the orbit, and the deformation of each body. The goal is to present good models for the tidal forces that take into account the possibly different rheology of each body. The equations are obtained within a finite dimension Lagrangian framework with dissipation function. The main contribution is a procedure to associate to each spring-dashpot model, which defines the rheology of a body, a potential and a dissipation function for the body deformation variables. The theory is applied to the Earth (solid part plus oceans) and a comparison between model and observation of the following quantities is made: norm of the Love numbers, rate of tidal energy dissipation, Chandler period, and Earth-Moon distance increase.
Huang, Wei; Yang, Xiao-xu; Han, Jun-feng; Wei, Yu; Zhang, Jing; Xie, Mei-lin; Yue, Peng
2016-01-01
High precision tracking platform of celestial navigation with control mirror servo structure form, to solve the disadvantages of big volume and rotational inertia, slow response speed, and so on. It improved the stability and tracking accuracy of platform. Due to optical sensor and mirror are installed on the middle-gimbal, stiffness and resonant frequency requirement for high. Based on the application of finite element modality analysis theory, doing Research on dynamic characteristics of the middle-gimbal, and ANSYS was used for the finite element dynamic emulator analysis. According to the result of the computer to find out the weak links of the structure, and Put forward improvement suggestions and reanalysis. The lowest resonant frequency of optimization middle-gimbal avoid the bandwidth of the platform servo mechanism, and much higher than the disturbance frequency of carrier aircraft, and reduces mechanical resonance of the framework. Reaching provides a theoretical basis for the whole machine structure optimization design of high-precision of autonomous Celestial navigation tracking mirror system.
Schroedinger Equation and the Quantization of Celestial Systems
Directory of Open Access Journals (Sweden)
Smarandache F.
2006-04-01
Full Text Available In the present article, we argue that it is possible to generalize Schroedinger equation to describe quantization of celestial systems. While this hypothesis has been described by some authors, including Nottale, here we argue that such a macroquantization was formed by topological superfluid vortice. We also provide derivation of Schroedinger equation from Gross-Pitaevskii-Ginzburg equation, which supports this superfluid dynamics interpretation.
A Celestial Assisted INS Initialization Method for Lunar Explorers
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Jiancheng Fang
2011-07-01
Full Text Available The second and third phases of the Chinese Lunar Exploration Program (CLEP are planning to achieve Moon landing, surface exploration and automated sample return. In these missions, the inertial navigation system (INS and celestial navigation system (CNS are two indispensable autonomous navigation systems which can compensate for limitations in the ground based navigation system. The accurate initialization of the INS and the precise calibration of the CNS are needed in order to achieve high navigation accuracy. Neither the INS nor the CNS can solve the above problems using the ground controllers or by themselves on the lunar surface. However, since they are complementary to each other, these problems can be solved by combining them together. A new celestial assisted INS initialization method is presented, in which the initial position and attitude of the explorer as well as the inertial sensors’ biases are estimated by aiding the INS with celestial measurements. Furthermore, the systematic error of the CNS is also corrected by the help of INS measurements. Simulations show that the maximum error in position is 300 m and in attitude 40″, which demonstrates this method is a promising and attractive scheme for explorers on the lunar surface.
Institute of Scientific and Technical Information of China (English)
Nicole Capitaine
2012-01-01
of astrometry,celestial mechanics,geodynamics,geodesy,etc.Of special interest are the improvements in the model for variations in Earth's rotation,which,in turn,can provide better knowledge of the dynamics of the Earth's interior.These have also contributed to a significant improvement in the accuracy of the ephemerides of the solar system bodies as determined from modern measurements,with a large number of scientific applications.This paper recalls the main aspects of the recent IAU resolutions on reference systems as well as their consequences on the concepts,definitions,nomenclature and models that are suitable for the definition,realization and transformation of reference frames at a microarcsecond level.
The IAA Cosmic Study 'Protecting the Environment of Celestial Bodies'
Rettberg, Petra; Hofmann, Mahulena; Williamson, Mark
The study group tasked with producing this International Academy of Astronautics (IAA) `Cosmic Study' on Protecting the Environment of Celestial Bodies was formed under the aus-pices of IAA Commission V (Space Policy, Law Economy). The members of the international, multidisciplinary team assembled to undertake the Study accept, as a premise, the Planetary Protection Policy guidelines developed by COSPAR, which differentiate the degree of protec-tion according to the type of space activity and the celestial body under investigation (such that fly-by missions have less stringent requirements than lander missions, while Mars is `better protected' than the Moon). However, this Study goes deliberately beyond the interpretation of `Planetary Protection' as a set of methods for protecting the planets from biological con-tamination and extends consideration to the geophysical, industrial and cultural realms. The Study concludes that, from the perspective of current and future activities in outer space, present measures aimed at protecting the space environment are insufficient. Deficiencies in-clude a lack of suitable in-situ methods of chemical and biological detection and the absence of a systematic record of radioactive contaminants. Other issues identified by the Study include an insufficient legal framework, a shortage of effective economic tools and a lack of political will to address these concerns. It is expected that new detection methods under development, and the resultant increase in microbiological knowledge of the planetary surfaces, will lead to changes in the COSPAR planetary protection guidelines and bioburden limits. It is important, however, that any new approaches should not hamper future exploration and exploitation of celestial bodies more than absolutely necessary. The Study addresses the need to find a balance between protection and freedom of action. From a legal perspective, the Study concludes that a general consensus on protection of the
The Power of Stars How Celestial Observations Have Shaped Civilization
Penprase, Bryan E
2011-01-01
What are some of the connections that bind us to the stars? How have these connections been established? And how have people all around the world and throughout time reacted to the night sky, the sun and moon, in their poetry, mythology, rituals, and temples? This book explores the influence of the sky on both ancient and modern civilization, by providing a clear overview of the many ways in which humans have used the stars as an ordering principle in their cultures, and which today still inspire us intellectually, emotionally, and spiritually. The book explores constellation lore from around the world, celestial alignments of monuments and temples, both from ancient and modern civilizations, and the role the sky has played in the cultures of the Greek, Egyptian, Babylonian, Native American, Chinese, Mayan, Aztec, and Inca. Models of the universe from each of these cultures are described clearly, and each culture’s explanation of the stars, planets, and other celestial objects are described. The roots of as...
On the abundance of deuterium in celestial objects
Lundin, Rickard; Kero, Johan; Liszka, Ludwik
2016-04-01
The deuterium hydrogen ratio (D/H) is the subject of conflicting ideas about the origin of water on the Earth. The present D/H ratio in the Earth oceans (≈1.5x10-4) is substantially lower than most, if not all potential cosmic sources. Furthermore, other celestial bodies, including interstellar space, display a fairly wide range of D/H ratios superseding the terrestrial one. Escape processes may in part explain higher D/H ratios on Mars and Venus, but cannot explain the Earth's low ratio compared to that of the potential sources (e.g. comets and meteors), unless a deuterium "removal" process can be inferred that reduces the D/H ratio. Alternatively, the D/H ratio in the Earth's ocean represents a time capsule of a yet to be identified cosmic source. It is here hypothesized that the former is the cause, a "removal" of deuterium in matter (carbohydrates, water etc.) having high (pristine) D/H ratios. By "removal" is here meant an isotope transmutation, i.e. deuterium is transmuted to hydrogen plus a thermal neutron, a process requiring >2.25 MeV (≈3.6·10-13 J). However, once released a thermal neutron will eventually fuse with another heavier element by thermal neutron capture, a process that may lead to energy in excess of the spallation energy. The energy gain differs for different isotopes, but if exceeding unity it will induce more heat/power than the input power, maintaining power production over time. A gain less than unity will still result in deuterium removal, but also isotope transmutation, and/or element transmutation via β± decay. This report gives a theoretical background for the plasma forcing that can lead to thermal neutron spallation, a process that changes/decrease the D/H ratio in celestial objects. The applicability of the theory will be tested on celestial objects subjected to strong dynamic, and electromagnetic forcing, by the Sun or during the entry of high-speed objects into the Earth's atmosphere.
Celestial Navigation Fix Based on Particle Swarm Optimization
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Tsou Ming-Cheng
2015-09-01
Full Text Available A technique for solving celestial fix problems is proposed in this study. This method is based on Particle Swarm Optimization from the field of swarm intelligence, utilizing its superior optimization and searching abilities to obtain the most probable astronomical vessel position. In addition to being applicable to two-body fix, multi-body fix, and high-altitude observation problems, it is also less reliant on the initial dead reckoning position. Moreover, by introducing spatial data processing and display functions in a Geographical Information System, calculation results and chart work used in Circle of Position graphical positioning can both be integrated. As a result, in addition to avoiding tedious and complicated computational and graphical procedures, this work has more flexibility and is more robust when compared to other analytical approaches.
The ancient Armenian calendars' connection with the celestial bodies
Broutian, G. H.
2015-07-01
The two oldest Armenian calendars - the Haykian and Protohaykian calendars were connected with observations of celestial bodies. Particularly since 2341 B.C. the heliacal rising of the first star of Orion was used to determine the day of the main holiday - Nawasard. Before that the observations of the same star were used in Protohaykian calendar to determine both the beginning and the end of the year. The year was determined as the duration of visibility of the star Betelgeuse. The year started with the heliacal rising of this star and ended with its heliacal setting. The remaining duration was considered to be out of the year. There are also evidences in Armenian medieval literary sources concerning the observations of heliacal rising and setting of Pleiades. An attempt was made to substantiate that the large symbol carved on the rock platform of the small hill in Metzamor also concerns to the Pleiades and shows the direction of heliacal rising of Pleiades.
Incontri celesti, vita del padre Clavio in cinque atti
Sigismondi, Costantino
2011-01-01
The year 2012 will be the fourth centennial year of the Jesuit Christopher Clavius (1535-1612), known as the Euclid of XVI century and the collaborator of the Pope Gregory XIII for the calendar reformation. In the occasion of the year of astronomy I wrote a short theatre pi\\`ece "Celestial encounters" dedicated to the life of Ft. Clavius. He observed two total eclipses from centreline in 1560 in Coimbra and in 1567 in Rome, a fact which is remarkable even for contemporary astronomers. The story is developed around those trips: scientific and religious motivations are put in evidence with historical and fantasy, but realistic, facts. An interregional project between Switzerland and Italy, dedicated to the development of high resolution CMOS camera for astronomy and medical sciences has been entitled to Clavius and will produce high resolution measurements of solar diameter.
Celestial Navigation in the USA, Fiji, and Tunisia
Holbrook, Jarita C.
2015-05-01
Today there are many coastal communities that are home to navigators who use stars for position finding at night; I was, however, unaware of this fact when I began researching celestial navigation practices in 1997. My project focused on three communities: the Moce Islanders of Fiji, the Kerkennah Islanders in Tunisia, and the U.S. Navy officers and students at the United States Naval Academy, Annapolis, Maryland. My goal was to answer the question of why people continue to navigate by the stars, but also to understand the role of technology in their navigation practices. Using anthropology techniques of ethnography including participant observation, formal and informal interviews, audio and videotaping, I gathered data over five years at the three communities. I began by learning the details of how they use the stars for navigation. Next, I learned about who did the navigation and where they learned to navigate. I gathered opinions on various navigation aids and instruments, and opinions about the future of using the stars for navigation. I listened to the stories that they told about navigating. In the United States I worked in English, in Fiji, in Fijian and English, and in Tunisia, French and English. For the formal interviews I worked with translators. The navigators use stars for navigating today but the future of their techniques is not certain. Though practiced today, these celestial navigation traditions have undergone and continue to undergo changes. New navigational technologies are part of the stimulation for change, thus 'a meeting of different worlds' is symbolized by peoples encounters with these technologies.
Numeric calculation of celestial bodies with spreadsheet analysis
Koch, Alexander
2016-04-01
The motion of the planets and moons in our solar system can easily be calculated for any time by the Kepler laws of planetary motion. The Kepler laws are a special case of the gravitational law of Newton, especially if you consider more than two celestial bodies. Therefore it is more basic to calculate the motion by using the gravitational law. But the problem is, that by gravitational law it is not possible to calculate the state of motion with only one step of calculation. The motion has to be numerical calculated for many time intervalls. For this reason, spreadsheet analysis is helpful for students. Skills in programmes like Excel, Calc or Gnumeric are important in professional life and can easily be learnt by students. These programmes can help to calculate the complex motions with many intervalls. The more intervalls are used, the more exact are the calculated orbits. The sutdents will first get a quick course in Excel. After that they calculate with instructions the 2-D-coordinates of the orbits of Moon and Mars. Step by step the students are coding the formulae for calculating physical parameters like coordinates, force, acceleration and velocity. The project is limited to 4 weeks or 8 lessons. So the calcualtion will only include the calculation of one body around the central mass like Earth or Sun. The three-body problem can only be shortly discussed at the end of the project.
Celestial delights the best astronomical events through 2020
Reddy, Francis
2012-01-01
Celestial Delights is the essential 'TV Guide' for the sky. Through extensive graphics integrated with an eight-year-long calendar of sky events, it provides a look at "don't miss" sky events, mostly for naked-eye and binocular observing. It is organized by ease of observation – lunar phases and the brighter planets come first, with solar eclipses, the aurora, and comets coming later. This third edition also includes a hefty dose of sky lore, astronomical history, and clear overviews of current science. It provides a handy reference to upcoming naked-eye events, with information broken out in clear and simple diagrams and tables that are cross-referenced against a detailed almanac for each year covered. This book puts a variety of information all in one place, presents it in a friendly way that does not require prior in-depth astronomical knowledge, and provides the context and historical background for understanding events that astronomy software or web sites lack.
The periodic dynamics of the irregular heterogeneous celestial bodies
Lan, Lei; Yang, Mo; Baoyin, Hexi; Li, Junfeng
2017-02-01
In this paper, we develop a methodology to study the periodic dynamics of irregular heterogeneous celestial bodies. Heterogeneous bodies are not scarce in space. It has been found that bodies, such as 4 Vesta, 624 Hektor, 87 Sylvia, 16 Psyche and 25143 Itokawa, may all have varied internal structures. They can be divided into large-scale and small-scale cases. The varied internal structures of large-scale bodies always result from gradient pressure inside, which leads to compactness differences of the inner material. However, the heterogeneity of a small-scale body is always reflected by the different densities of different areas, which may originate from collision formation from multiple objects. We propose a modeling procedure for the heterogeneous bodies derived from the conventional polyhedral method and then compare its dynamical characteristics with those of the homogeneous case. It is found that zero-velocity curves, positions of equilibrium points, types of bifurcations in the continuation of the orbital family and the stabilities of periodic orbits near the heterogeneous body are different from those in the homogeneous case. The suborbicular orbits near the equatorial plane are potential parking orbits for a future mission, so we discuss the switching of the orbital stability of the family because it has fundamental significance to orbit maintenance and operations around actual asteroids.
Advanced Spacecraft Navigation and Timing Using Celestial Gamma-Ray Sources Project
National Aeronautics and Space Administration — The proposed novel program will use measurements of the high-energy photon output from gamma-ray celestial sources to design a new, unique navigation system. This...
Long-term Dynamical Behavior of Highly Perturbed Natural and Artificial Celestial Bodies
Rosengren, Aaron J.
This thesis explores the dynamical evolution of celestial bodies, both natural and artificial, which are strongly perturbed by solar radiation pressure---a non-gravitational force that has played an increasingly important role in celestial mechanics since the early 1900s. The particular focus is on the high area-to-mass ratio (HAMR) space debris discovered in near geosynchronous Earth orbit (GEO) through optical observations in 2004, and on micron-sized circumplanetary dust particles in the outer Saturnian system. The formalism developed can also be applied to---and, indeed, was unquestionably influenced by---the orbital motion of spacecraft about small bodies (asteroids and comets). The chief difficulties which arise in getting an accurate understanding of the motion of such bodies in highly perturbed dynamical environments come, in part, from the nonlinearity of the dynamical system, but more so from the inadequacy of the classical approaches and methods. While modern formulations based on numerical integrations can give "precise" solutions for specific initial conditions, these afford little insight into the nature of the problem or the essential dependence of the perturbed motion on the system parameters. The predominant perturbations acting on HAMR objects and circumplanetary dust grains are solar radiation pressure, planetary oblateness, and third-body gravitational interactions induced by the Sun and nearby natural satellites. We developed first-order averaged models, based on the Milankovitch formulation of perturbation theory, which govern the long-term evolution of orbits subject to these perturbing forces. The unexpectedly rich results obtained by the use of this vector formalism are due to certain important circumstances in celestial and quantum mechanics which gave rise to its origin and development. An attempt has been made to trace these historical developments and to put them into the perspective of the present. The averaged equations of motion hold
Legge, Eric L G; Wystrach, Antoine; Spetch, Marcia L; Cheng, Ken
2014-12-01
Insects typically use celestial sources of directional information for path integration, and terrestrial panoramic information for view-based navigation. Here we set celestial and terrestrial sources of directional information in conflict for homing desert ants (Melophorus bagoti). In the first experiment, ants learned to navigate out of a round experimental arena with a distinctive artificial panorama. On crucial tests, we rotated the arena to create a conflict between the artificial panorama and celestial information. In a second experiment, ants at a feeder in their natural visually-cluttered habitat were displaced prior to their homing journey so that the dictates of path integration (feeder to nest direction) based on a celestial compass conflicted with the dictates of view-based navigation (release point to nest direction) based on the natural terrestrial panorama. In both experiments, ants generally headed in a direction intermediate to the dictates of celestial and terrestrial information. In the second experiment, the ants put more weight on the terrestrial cues when they provided better directional information. We conclude that desert ants weight and integrate the dictates of celestial and terrestrial information in determining their initial heading, even when the two directional cues are highly discrepant.
The Inner Meaning of Outer Space: Human Nature and the Celestial Realm
Directory of Open Access Journals (Sweden)
Timothy L. Hubbard
2008-06-01
Full Text Available Kant argued that humans possess a priori knowledge of space; although his argument focused on a physics of bodies, it also has implications for a psychology of beings. Many human cultures organize stars in the night sky into constellations (i.e., impose structure; attribute properties, behaviors, and abilities to objects in the celestial realm (i.e., impose meaning; and use perceived regularity in the celestial realms in development of calendars, long-range navigation, agriculture, and astrology (i.e., seek predictability and control. The physical inaccessibility of the celestial realm allows a potent source of metaphor, and also allows projection of myths regarding origin and ascension, places of power, and dwelling places of gods, immortals, and other souls. Developments in astronomy and cosmology infl uenced views of human nature and the place of humanity in the universe, and these changes parallel declines in egocentrism with human development. Views regarding alleged beings (e.g., angels, extraterrestrials from the celestial realm (and to how communicate with such beings are anthropocentric and ignore evolutionary factors in physical and cognitive development. It is suggested that in considering views and uses of the celestial realm, we learn not just about the universe, but also about ourselves. *
Forecasting scenarios of collision catastrophes produced by celestial body falls
Shor, V.; Kochetova, O.; Chernetenko, Y.; Zheleznov, N.; Deryugin, V.; Zaitsev, A.
2014-07-01
The subject under discussion arose in the course of developing a computer program, which gives the possibility for numerical and graphical modeling of the scenarios of catastrophes caused by collisions of cosmic bodies with the Earth. It is expected that this program can be used for computer-assisted training of the personnel of units of the Ministry for Emergency Situations in the case of a situation caused by the fall of a celestial body on the Earth. Also, it is anticipated that the program can be used in real situations when a dangerous body is discovered on an orbit leading to an imminent collision with the Earth. From the scientific point of view, both variants of use require solving of analogous tasks. In what follows, we discuss both variants. 1. The computation of the circumstances for a fall on the Earth (or approach within short distance) of a real body begins with the determination of its orbit from the observations available using the least-squares method. The mean square error of the representation of the observations on the base of the initial values of the coordinates and the velocities is computed, as well as their covariance matrix. Then, the trajectory of the body's motion is followed by numerical integration starting from the osculating epoch to the collision with the Earth or to its flyby. The computer program takes into account the various cases: at the initial moment, the body can move away from or approach the Earth, it can be outside the sphere of action or inside it. At the moment, when the body enters the sphere of action, the coordinates of the center of the dispersion ellipse on the target plane are computed as well as the dimensions of its axes. Using these data, the probability of collision with the Earth is calculated. Then, the point of penetration of the body into the Earth's atmosphere at a given height above the level of the Earth geoid is determined. In case the body is passing by the Earth, the minimum distance of the body from
Illustrating the phaenomena celestial cartography in antiquity and the Middle Ages
Dekker, Elly
2013-01-01
In this volume all extant celestial maps and globes made before 1500 are described and analysed. It also discusses the astronomical sources involved in making these artefacts in antiquity, the Middle Ages, the Islamic world and the European Renaissance before 1500.
The Gravitational Effects of a Celestial Body with Magnetic Charge and Moment
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The gravitational effects (precession of charge-less particles and deflection of light) in the gravitational field of a celestial body with magnetic charge and moment (CM)are investigated. We found that the magnetic charge always weakens the pure Schwarzschild effects, while the magnetic dipole moment deforms the effects in a more complicated way.
Gessner, Samuel
2015-01-01
The aim of this paper is to examine the iconography on a set of star charts by Albrecht Dürer (1515), and celestial globes by Caspar Vopel (1536) and Christoph Schissler (1575). The iconography on these instruments is conditioned by strong traditions which include not only the imagery on globes and planispheres (star charts), but also ancient literature about the constellations. Where this iconography departs from those traditions, the change had to do with humanism in the sixteenth century. This "humanistic" dimension is interwoven with other concerns that involve both "social" and "technical" motivations. The interplay of these three dimensions illustrates how the iconography on celestial charts and globes expresses some features of the shared knowledge and shared culture between artisans, mathematicians, and nobles in Renaissance Europe.
UBVRI Photometric Standard Stars Around the Celestial Equator: Updates and Additions
Landolt, Arlo U
2009-01-01
New broadband UBVRI photoelectric observations on the Johnson-Kron-Cousins photometric system have been made of 202 stars around the sky, and centered at the celestial equator. These stars constitute both an update of and additions to a previously published list of equatorial photometric standard stars. The list is capable of providing, for both celestial hemispheres, an internally consistent homogeneous broadband standard photometric system around the sky. When these new measurements are included with those previously published by Landolt (1992), the entire list of standard stars in this paper encompasses the magnitude range 8.90 < V < 16.30, and the color index range -0.35 < (B - V) < +2.30.
IN-FLIGHT ALIGNMENT OF INERTIAL NAVIGATION SYSTEM BY CELESTIAL OBSERVATION TECHNIQUE
Institute of Scientific and Technical Information of China (English)
ALlJamshaid; FANGJian-cheng
2005-01-01
This paper presents an in-flight alignment technique for a strapdown inertial navigation system (SINS) and employs a star pattern recognition procedure for identifying stars sensed by a CCD electrooptical star sensor.Collinearity equations are used to estimate sensor frame star coordinates and the conventional least square differential correction method is used to estimate the unknown orientation angles. A comparison of this attitude with the attitude estimated by the SINS provides axis misalignment angles. Simulations using a Kalman filter are carried out for an SINS and the system employs a local level navigation frame. The space stabilized SINS is discussed in conjunction with the celestial aiding. Based on the observation of the Kalman filter, the estimating and compensating gyro errors, as well as the position and velocity errors caused by the SINS misalignments are calibrated by celestial attitute information.
The impact of celestial pole offset modelling on VLBI UT1 Intensive results
Malkin, Zinovy
2011-01-01
Very Long Baseline Interferometry (VLBI) Intensive sessions are scheduled to provide operational Universal Time (UT1) determinations with low latency. UT1 estimates obtained from these observations heavily depend on the model of the celestial pole motion used during data processing. However, even the most accurate precession-nutation model, IAU 2000/2006, is not accurate enough to realize the full potential of VLBI observations. To achieve the highest possible accuracy in UT1 estimates, a celestial pole offset (CPO), which is the difference between the actual and modelled precession-nutation angles, should be applied. Three CPO models are currently available for users. In this paper, these models have been tested and the differences between UT1 estimates obtained with those models are investigated. It has been shown that neglecting CPO modelling during VLBI UT1 Intensive processing causes systematic errors in UT1 series of up to 20 microarcseconds. It has been also found that using different CPO models causes...
Energy Technology Data Exchange (ETDEWEB)
Titov, O.; Stanford, Laura M. [Geoscience Australia, P.O. Box 378, Canberra, ACT 2601 (Australia); Johnston, Helen M.; Hunstead, Richard W. [Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia); Pursimo, T. [Nordic Optical Telescope, Nordic Optical Telescope Apartado 474E-38700 Santa Cruz de La Palma, Santa Cruz de Tenerife (Spain); Jauncey, David L. [CSIRO Astronomy and Space Science, ATNF and Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Maslennikov, K. [Central Astronomical Observatory at Pulkovo, Pulkovskoye Shosse, 65/1, 196140, St. Petersburg (Russian Federation); Boldycheva, A., E-mail: oleg.titov@ga.gov.au [Ioffe Physical Technical Institute, 26 Polytekhnicheskaya, St. Petersburg, 194021 (Russian Federation)
2013-07-01
Continuing our program of spectroscopic observations of International Celestial Reference Frame (ICRF) sources, we present redshifts for 120 quasars and radio galaxies. Data were obtained with five telescopes: the 3.58 m European Southern Observatory New Technology Telescope, the two 8.2 m Gemini telescopes, the 2.5 m Nordic Optical Telescope (NOT), and the 6.0 m Big Azimuthal Telescope of the Special Astrophysical Observatory in Russia. The targets were selected from the International VLBI Service for Geodesy and Astrometry candidate International Celestial Reference Catalog which forms part of an observational very long baseline interferometry (VLBI) program to strengthen the celestial reference frame. We obtained spectra of the potential optical counterparts of more than 150 compact flat-spectrum radio sources, and measured redshifts of 120 emission-line objects, together with 19 BL Lac objects. These identifications add significantly to the precise radio-optical frame tie to be undertaken by Gaia, due to be launched in 2013, and to the existing data available for analyzing source proper motions over the celestial sphere. We show that the distribution of redshifts for ICRF sources is consistent with the much larger sample drawn from Faint Images of the Radio Sky at Twenty cm (FIRST) and Sloan Digital Sky Survey, implying that the ultra-compact VLBI sources are not distinguished from the overall radio-loud quasar population. In addition, we obtained NOT spectra for five radio sources from the FIRST and NRAO VLA Sky Survey catalogs, selected on the basis of their red colors, which yielded three quasars with z > 4.
An Overview of Major Terrestrial, Celestial, and Temporal Coordinate Systems for Target Tracking
2016-08-10
quadrant inverse tangent in (B2) is not uniquely defined at the poles (when x “ 0 and y “ 0). However, many implementations of the four-quadrant inverse ...Harmonic Coordinates .................................... 105 APPENDIX E—Principal Axes, Precession, Nutation, and the Pole Tide...on the Celestial Sphere z ` Pole of the Ecliptic ˘ x ˆ IERS Reference Meridian « Dynamical Equinox at Epoch ˙ , P z ` IERS Reference Pole
Rotating space elevators: Physics of celestial scale spinning strings
Knudsen, Steven; Golubović, Leonardo
2014-11-01
We explore classical and statistical mechanics of a novel dynamical system, the Rotating Space Elevator (RSE) (L. Golubović, S. Knudsen, EPL 86, 34001 (2009)). The RSE is a double rotating floppy string reaching extraterrestrial locations. Objects sliding along the RSE string (climbers) do not require internal engines or propulsion to be transported far away from the Earth's surface. The RSE thus solves a major problem in space elevator science, which is how to supply energy to the climbers moving along space elevator strings. The RSE can be made in various shapes that are stabilized by an approximate equilibrium between the gravitational and inertial forces acting in a double rotating frame associated with the RSE. This dynamical equilibrium is achieved by a special ("magical") form of the RSE mass line density derived in this paper. The RSE exhibits a variety of interesting dynamical phenomena explored here by numerical simulations. Thanks to its special design, the RSE exhibits everlasting double rotating motion. Under some conditions, however, we find that the RSE may undergo a morphological transition to a chaotic state reminiscent of fluctuating directed polymers in the realm of the statistical physics of strings and membranes.
Risk of Adverse Health and Performance Effects of Celestial Dust Exposure
Scully, Robert R.; Meyers, Valerie E.
2015-01-01
Crew members can be directly exposed to celestial dust in several ways. After crew members perform extravehicular activities (EVAs), they may introduce into the habitat dust that will have collected on spacesuits and boots. Cleaning of the suits between EVAs and changing of the Environmental Control Life Support System filters are other operations that could result in direct exposure to celestial dusts. In addition, if the spacesuits used in exploration missions abrade the skin, as current EVA suits have, then contact with these wounds would provide a source of exposure. Further, if celestial dusts gain access to a suit's interior, as was the case during the Apollo missions, the dust could serve as an additional source of abrasions or enhance suit-induced injuries. When a crew leaves the surface of a celestial body and returns to microgravity, the dust that is introduced into the return vehicle will "float," thus increasing the opportunity for ocular and respiratory injury. Because the features of the respirable fraction of lunar dusts indicate they could be toxic to humans, NASA conducted several studies utilizing lunar dust simulants and authentic lunar dust to determine the unique properties of lunar dust that affect physiology, assess the dermal and ocular irritancy of the dust, and establish a permissible exposure limit for episodic exposure to airborne lunar dust during missions that would involve no more than 6 months stay on the lunar surface. Studies, with authentic lunar soils from both highland (Apollo 16) and mare (Apollo17) regions demonstrated that the lunar soil is highly abrasive to a high fidelity model of human skin. Studies of lunar dust returned during the Apollo 14 mission from an area of the moon in which the soils were comprised of mineral constituents from both major geological regions (highlands and mares regions) demonstrated only minimal ocular irritancy, and pulmonary toxicity that was less than the highly toxic terrestrial crystalline
Maoret, Francesco; Beltrami, Giulia; Bertolucci, Cristiano; Foà, Augusto
2014-04-01
The present investigation was aimed at testing whether the lizard sky polarization compass is time compensated. For this purpose, ruin lizards, Podarcis sicula, were both trained and tested for orientation inside a Morris water maze under clear skies with the sun not in view. During training, lizards showed a striking bimodal orientation along the training axis, demonstrating their capability of determining the symmetry plane of the sky polarization pattern and thus the use of polarization information in orientation. After reaching criteria, lizards were kept 7 days in a 6-h fast clock-shift treatment and then released with the sun not in view. Six-hour clock-shifted lizards showed a bimodal distribution of directional choices, which was oriented perpendicularly to the training axis, as it was expected on the basis of the clock-shift. The results show that the only celestial diurnal compass mechanism that does not need a direct vision of the sun disk (i.e., the sky polarization compass) is a time-compensated compass.
Ferronsky, V I; Ferronsky, S V
2011-01-01
In their approach to Earth dynamics the authors consider the fundamentals of Jacobi Dynamics (1987, Reidel) for two reasons. First, because satellite observations have proved that the Earth does not stay in hydrostatic equilibrium, which is the physical basis of today’s treatment of geodynamics. And secondly, because satellite data have revealed a relationship between gravitational moments and the potential of the Earth’s outer force field (potential energy), which is the basis of Jacobi Dynamics. This has also enabled the authors to come back to the derivation of the classical virial theorem and, after introducing the volumetric forces and moments, to obtain a generalized virial theorem in the form of Jacobi’s equation. Thus a physical explanation and rigorous solution was found for the famous Jacobi’s equation, where the measure of the matter interaction is the energy. The main dynamical effects which become understandable by that solution can be summarized as follows: • the kinetic energy of osci...
Spectrum of the Anomalous Microwave Emission in the North Celestial Pole with WMAP 7-Year data
Bonaldi, Anna; 10.1155/2012/853927
2013-01-01
We estimate the frequency spectrum of the diffuse anomalous microwave emission (AME) on the North Celestial Pole (NCP) region of the sky with the Correlated Component Analysis (CCA) component separation method applied to WMAP 7-yr data. The NCP is a suitable region for this analysis because the AME is weakly contaminated by synchrotron and free-free emission. By modeling the AME component as a peaked spectrum we estimate the peak frequency to be $21.7\\pm0.8$\\,GHz, in agreement with previous analyses which favored $\
Brightness and color of the integrated starlight at celestial, ecliptic and galactic poles
Nawar, S; Mikhail, J S; Morcos, A B
2010-01-01
From photoelectric observations of night sky brightness carried out at Abu-Simbel, Asaad et al. (1979) have obtained values of integrated starlight brightness at different Galactic latitudes. These data have been used in the present work to obtain the brightness and color of the integrated starlight at North and South Celestial, Ecliptic and Galactic Poles. The present values of the brightness are expressed in S10 units and mag/arcsec2. Our results have been compared with that obtained by other investigators using photometric and star counts techniques. The B-V and B-R have been calculated and the results are compared with that obtained by other investigators.
Method of separation of celestial gamma-ray bursts from solar flares
Energy Technology Data Exchange (ETDEWEB)
Chuang, K.W.; White, R.S. (Institute of Geophysics and Planetary Physics, UC Riverside, California 92521 (United States)); Klebesadel, R.W.; Laros, J.G. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States))
1991-09-01
We recently discovered 217 new'' celestial gamma-ray burst candidates from the new'' burst search of the PVO real time data base.[sup 1] The burst search covered the time period from September 1978 to July 1988. Sixty were confirmed by at lest on other spacecraft, e.g., ISEE-3, V-11, V-12, etc. None triggered the PVO high time resolution memory. In this paper we describe a new algorithm based ont eh relationship between time width [ital T][sub [ital w
Malkin, Z; Arias, F; Boboltz, D; Boehm, J; Bolotin, S; Bourda, G; Charlot, P; De Witt, A; Fey, A; Gaume, R; Heinkelmann, R; Lambert, S; Ma, C; Nothnagel, A; Seitz, M; Gordon, D; Skurikhina, E; Souchay, J; Titov, O
2015-01-01
The goal of this presentation is to report the latest progress in creation of the next generation of VLBI-based International Celestial Reference Frame, ICRF3. Two main directions of ICRF3 development are improvement of the S/X-band frame and extension of the ICRF to higher frequencies. Another important task of this work is the preparation for comparison of ICRF3 with the new generation optical frame GCRF expected by the end of the decade as a result of the Gaia mission.
Celestial harvest 300-plus showpieces of the heavens for telescope viewing and contemplation
Mullaney, James
2012-01-01
This book describes over 300 celestial wonders that can be viewed with common binoculars and low-power ""backyard"" telescopes incorporating refractors and reflectors.In addition to such showpieces as the Andromeda Galaxy, the largest and brightest of all galaxies after the Milky Way, and the Blue Snowball, one of the autumn sky's outstanding planetary nebulas, over 20 other special objects are listed and characterized, many of which are visible to the unaided eye on a dark, clear night.The sun, moon, Venus, Mars, Jupiter, Saturn, and other members of the earth's solar system are also describ
On one-way Doppler measurements of space craft and celestial objects
Jochim, E. F. M.
2010-01-01
The orbital velocity of a spacecraft and other celestial objects is monitored by observing the Doppler frequency shift of the signals received at the ground station. This is possible one-way in case the transmitted frequency is stable enough. In most spacecraft a calibrated transponder allows two-way Doppler frequency registrations. In general, the factor 2 is expected as the quotient between two- and one-way frequencies. However, this is no longer the case when the motion of the observed object deviates from the orbit as predicted. Frequency differences appear. Porsche (1999) has published a formula to describe these differences based on the assumption of a double projection of the true velocity vector. In the present paper a more sophisticated analysis of the influence of state errors on the track-ing results is deduced. This theory has been tested by the Doppler measurements during flybys of the comet space probe GIOTTO penetrating through the comae of the comets P/Halley and P/Grigg-Skjellerup. One-way Doppler measurements of the low Earth satellites CHAMP and TERRASAR-X show a tendency for the applicability of this approach. Finally, some conse-quences for the observation of other celestial objects are discussed.
A Ka-band Celestial Reference Frame with Applications to Deep Space Navigation
Jacobs, Christopher S.; Clark, J. E.; García-Miró, C.; Horiuchi, S.; Sotuela, I.
2011-10-01
The Ka-band radio spectrum is now being used for a wide variety of applications. This paper highlights the use of Ka-band as a frequency for precise deep space navigation based on a set of reference beacons provided by extragalactic quasars which emit broadband noise at Ka-band. This quasar-based celestial reference frame is constructed using X/Ka-band (8.4/32 GHz) from fifty-five 24-hour sessions with the Deep Space Network antennas in California, Australia, and Spain. We report on observations which have detected 464 sources covering the full 24 hours of Right Ascension and declinations down to -45 deg. Comparison of this X/Ka-band frame to the international standard S/X-band (2.3/8.4 GHz) ICRF2 shows wRMS agreement of ~200 micro-arcsec (μas) in α cos δ and ~300 μas in δ. There is evidence for systematic errors at the 100 μas level. Known errors include limited SNR, lack of instrumental phase calibration, tropospheric refraction mis-modeling, and limited southern geometry. The motivation for extending the celestial reference frame to frequencies above 8 GHz is to access more compact source morphology for improved frame stability and to support spacecraft navigation for Ka-band based NASA missions.
A Ka-Band Celestial Reference Frame with Applications to Deep Space Navigation
Jacobs, Christopher S.; Clark, J. Eric; Garcia-Miro, Cristina; Horiuchi, Shinji; Sotuela, Ioana
2011-01-01
The Ka-band radio spectrum is now being used for a wide variety of applications. This paper highlights the use of Ka-band as a frequency for precise deep space navigation based on a set of reference beacons provided by extragalactic quasars which emit broadband noise at Ka-band. This quasar-based celestial reference frame is constructed using X/Ka-band (8.4/32 GHz) from fifty-five 24-hour sessions with the Deep Space Network antennas in California, Australia, and Spain. We report on observations which have detected 464 sources covering the full 24 hours of Right Ascension and declinations down to -45 deg. Comparison of this X/Ka-band frame to the international standard S/X-band (2.3/8.4 GHz) ICRF2 shows wRMS agreement of approximately 200 micro-arcsec in alpha cos(delta) and approximately 300 micro-arcsec in delta. There is evidence for systematic errors at the 100 micro-arcsec level. Known errors include limited SNR, lack of instrumental phase calibration, tropospheric refraction mis-modeling, and limited southern geometry. The motivation for extending the celestial reference frame to frequencies above 8 GHz is to access more compact source morphology for improved frame stability and to support spacecraft navigation for Ka-band based NASA missions.
Is the aether entrained by the motion of celestial bodies? What do the experiments tell us?
Levy, Joseph
2012-01-01
Even though the concept has evolved and if the designation as aether is improperly regarded as outdated, nobody today considers that the vacuum is empty. However, the nature and the properties of the substratum, which permeates the entire universe, remain for the most part unspecified. For example, divergent opinions are put forward by physicists about a possible dragging of the aether by the translational motion of celestial bodies due to gravitation. We show in this text that such a hypothesis is inconsistent with well established experimental data which, on the contrary, lend support to non-entrained aether theory based on Lorentz contraction. A revaluation of the aether drift to which the Earth is subjected is carried out.
Directory of Open Access Journals (Sweden)
VIRGINIA SASU
2014-01-01
Full Text Available The main purpose of this paper is to reveal certain misconceptions of astronomical phenomena and of celestial bodies that lower secondary school pupils have and which might represent an obstacle in the process of acquiring knowledge of astronomy, geography, and physics. We applied a questionnaire to a group of 26 pupils in the 6th grade at Colegiul Naţional Pedagogic „Gh. Lazăr” (“Gh. Lazăr National Pedagogical College in Cluj-Napoca, in the school year 2010 – 2011. The questionnaire consisted of six independent topics: the alternation of day and night, the seasons, the Moon, the solar system, the constellations and the speed of light. Pupils’ answers to these questions emphasize the importance of the study of astronomy as a school subject in order to facilitate building up appropriate mind constructs of the highest degree of objectivity about the world, about the environment we live in.
Signature of the celestial spheres discovering order in the solar system
Warm, Harmut
2010-01-01
"A milestone in modern research on the the harmony of the spheres." - Novalis magazine "This book reignites the debate on the harmony of the spheres." - Das Goetheanum Is the solar system ordered, or is it simply the result of random and chaotic accidents? This book takes us on a powerful and compelling journey of discovery, revealing the celestial spheres' astonishingly complex patterns. The movements of the planets are found to correspond accurately with simple geometric figures and musical intervals, pointing to an exciting new perspective on the ancient idea of a "harmony of the spheres". Hartmut Warm's detailed presentation incorporates the distances, velocities and periods of conjunction of the planets, as well as the rotations of the Sun, Moon and Venus. Numerous graphics - including colour plates - illustrate the extraordinary beauty of the geometrical forms that result when the movements of several planets are viewed in relation to one another. In addition, the author describes and analyses the conce...
SAS-2 observations of celestial diffuse gamma radiation above 30 MeV
Thompson, D. J.; Fichtel, C. E.; Kniffen, D. A.; Hartman, R. C.
1974-01-01
The small astronomy satellite, SAS-2, used a 32-deck magnetic core digitized spark chamber to study gamma rays with energies above 30 MeV. Data for four regions of the sky away from the galactic plane were analyzed. These regions show a finite, diffuse flux of gamma rays with a steep energy spectrum, and the flux is uniform over all the regions. Represented by a power law, the differential energy spectrum shows an index of 2.5 + or - 0.4. The steep SAS-2 spectrum and the lower energy data are reasonably consistent with a neutral pion gamma-ray spectrum which was red-shifted (such as that proposed by some cosmological theories). It is concluded that the diffuse celestial gamma ray spectrum observed presents the possibility of cosmological studies and possible evidence for a residual cosmic ray density, and supports the galactic superclusters of matter and antimatter remaining from baryon-symmetric big bang.
International Celestial Reference Frame (ICRF): mantenimiento y extensión
Ma, C.; Arias, E. F.; Eubanks, T.; Fey, A. L.; Gontier, A.-M.; Jacobs, C. S.; Sovers, O. J.; Archinal, B. A.; Charlot, P.
A partir de enero de 1998 el sistema de referencia celeste convencional está representado por el International Celestial Reference System (ICRS) y materializado a través de las coordenadas VLBI del conjunto de radiofuentes extragalácticas que conforman el International Celestial Reference Frame (ICRF). La primera realización del ICRF, fue elaborada en 1995 por un grupo de expertos designado por la IAU, la que encomendó al International Earth Rotation Service el mantenimiento del ICRS, del ICRF y del vínculo con marcos de referencia en otras frecuencias. Una primera extensión del ICRF se realizó entre abril y junio de 1999, con el objetivo primario de proveer posiciones de radiofuentes extragalácticas observadas a partir de julio de 1995 y de mejorar las posiciones de las fuentes ``candidatas" con la inclusión de observaciones adicionales. Objetivos secundarios fueron monitorear a las radiofuentes para verificar que siguen siendo adecuadas para realizar al ICRF y mejorar las técnicas de análisis de datos. Como resultado del nuevo análisis se obtuvo una solución a partir de la cual se construyó la primera extensión del ICRF, denominada ICRF - Ext.1. Ella representa al ICRS, sus fuentes de definición se mantienen con las mismas posiciones y errores que en la primera realización del ICRF; las demás radiofuentes tienen coordenadas mejor determinadas que en ICRF; el marco de referencia se densificó con el agregado de 59 nuevas radiofuentes.
强不规则天体引力场中的动力学研究进展%Research Trend of Dynamics in the Gravitational Field of Irregular Celestial Body
Institute of Scientific and Technical Information of China (English)
姜宇; 宝音贺西
2014-01-01
Both asteroid and comet exploration are important areas in the deep space exploration.The mass of an asteroid or a comet is not big enough,so its gravitational force is much smaller than the stress to satisfy the hydrostatic equilibrium, which makes the minor celestial body irregular-shaped. The research of dynamical behaviours and mechanisms in the gravitational field of irregular celestial body is the basis of minor celestial body exploration,including the catching of the explorer and the design of the orbit around the minor celestial body.This paper summarizes the research progress of the dynamics in the gravitational field of irregular celestial body through gravitational models and dynamical mechanisms.The research situation of gravitational models such as the Legendre polynomial model,the simple-shaped model and the polyhedron model are presented.In addition,the research situation of dynamical mechanisms such as the periodic orbits and quasi-periodic orbits, equilibrium points, manifolds,bifurcations and resonances,chaos,are also presented.Besides,we have analyzed key points and difficult points of these researches.Finally,the research trend of the dynamics in the gravitational field of irregular celestial body is discussed.%小行星探测与彗星探测是深空探测的重要方面。一般来说，小行星和彗星因质量都不足以使得万有引力克服应力达到流体静力学平衡，而具有强不规则的外形。研究强不规则天体引力场中的动力学行为及其内在机制，是探测器被不规则天体捕获并对其形成近距离探测轨道的基础。从引力场模型和动力学行为两个方面综述了强不规则天体引力场中动力学的研究进展，在引力场模型的研究方面介绍了强不规则天体引力场建模的球谐函数摄动展开模型、简单特殊体模型及多面体模型的研究现状，在动力学机制的研究方面介绍了强不规则天体引力场中的
Krásná, Hana; Malkin, Zinovy; Böhm, Johannes
The increasing accuracy and growing time span of Very Long Baseline Interferometry (VLBI) observations allow the determination of seasonal signals in station positions which still remain unmodelled in conventional analysis approaches. In this study we focus on the impact of the neglected seasonal signals in the station displacement on the celestial reference frame and Earth orientation parameters. We estimate empirical harmonic models for selected stations within a global solution of all suitable VLBI sessions and create mean annual models by stacking yearly time series of station positions which are then entered a priori in the analysis of VLBI observations. Our results reveal that there is no systematic propagation of the seasonal signal into the orientation of celestial reference frame but position changes occur for radio sources observed non-evenly over the year. On the other hand, the omitted seasonal harmonic signal in horizontal station coordinates propagates directly into the Earth rotation parameters causing differences of several tens of microarcseconds.
Edward Burne-Jones’ The Days of Creation: A Celestial Utopia
Directory of Open Access Journals (Sweden)
Liana De Girolami Cheney
2014-09-01
Full Text Available Edward Burne-Jones’ cycle of The Days of Creation of 1870-66(Fogg Art Museum, Harvard University Museums, Cambridge, MA was highly praised and elegantly described by Oscar Wilde: “The picture is divided into six compartments, each representing a day in the Creation of the World, under the symbol of an angel holding a crystal globe, within which is shown the work of a day.” This essay examines how Burne-Jones visualized an unusual celestial creation where angels holding magical spheres unveil the divine manifestation for the creation of a terrestrial realm. His The Days of Creation is an aesthetic culmination of the artistic power of invention, imitation and creation of beauty. Burne-Jones borrows the divine concept of world creation to formulate his own artist creation. Selecting God’s week of creation, he empowers a daily angel to manifest the beauty and power of divine creation. Ultimately, Burne-Jones creates a cosmic utopia, a mythical heavenly and natural realm, where angels design a world of beauty to be emulated not only by the artist, but also by most of all by the viewer.
ASTEP South: An Antarctic Search for Transiting ExoPlanets around the celestial South pole
Crouzet, Nicolas; Agabi, Karim; Rivet, Jean-Pierre; Bondoux, Erick; Challita, Zalpha; Fanteï-Caujolle, Yan; Fressin, François; Mékarnia, Djamel; Schmider, François-Xavier; Valbousquet, Franck; Blazit, Alain; Bonhomme, Serge; Abe, Lyu; Daban, Jean-Baptiste; Gouvret, Carole; Fruth, Thomas; Rauer, Heike; Erikson, Anders; Barbieri, Mauro; Aigrain, Suzanne; Pont, Frédéric
2009-01-01
ASTEP South is the first phase of the ASTEP project (Antarctic Search for Transiting ExoPlanets). The instrument is a fixed 10 cm refractor with a 4kx4k CCD camera in a thermalized box, pointing continuously a 3.88 degree x 3.88 degree field of view centered on the celestial South pole. ASTEP South became fully functional in June 2008 and obtained 1592 hours of data during the 2008 Antarctic winter. The data are of good quality but the analysis has to account for changes in the point spread function due to rapid ground seeing variations and instrumental effects. The pointing direction is stable within 10 arcseconds on a daily timescale and drifts by only 34 arcseconds in 50 days. A truly continuous photometry of bright stars is possible in June (the noon sky background peaks at a magnitude R=15 arcsec-2 on June 22), but becomes challenging in July (the noon sky background magnitude is R=12.5 arcsec?2 on July 20). The weather conditions are estimated from the number of stars detected in the field. For the 2008...
Spectrum of the Anomalous Microwave Emission in the North Celestial Pole with WMAP 7-Year Data
Directory of Open Access Journals (Sweden)
Anna Bonaldi
2012-01-01
Full Text Available We estimate the frequency spectrum of the diffuse anomalous microwave emission (AME on the North Celestial Pole (NCP region of the sky with the Correlated Component Analysis (CCA component separation method applied to WMAP 7-yr data. The NCP is a suitable region for this analysis because the AME is weakly contaminated by synchrotron and free-free emission. By modeling the AME component as a peaked spectrum we estimate the peak frequency to be 21.7±0.8 GHz, in agreement with previous analyses which favored νp < 23 GHz. The ability of our method to correctly recover the position of the peak is verified through simulations. We compare the estimated AME spectrum with theoretical spinning dust models to constrain the hydrogen density nH. The best results are obtained with densities around 0.2–0.3 cm−3, typical of warm ionised medium (WIM to warm neutral medium (WNM conditions. The degeneracy with the gas temperature prevents an accurate determination of nH, especially for low hydrogen ionization fractions, where densities of a few cm−3 are also allowed.
Dual-EKF-Based Real-Time Celestial Navigation for Lunar Rover
Directory of Open Access Journals (Sweden)
Li Xie
2012-01-01
Full Text Available A key requirement of lunar rover autonomous navigation is to acquire state information accurately in real-time during its motion and set up a gradual parameter-based nonlinear kinematics model for the rover. In this paper, we propose a dual-extended-Kalman-filter- (dual-EKF- based real-time celestial navigation (RCN method. The proposed method considers the rover position and velocity on the lunar surface as the system parameters and establishes a constant velocity (CV model. In addition, the attitude quaternion is considered as the system state, and the quaternion differential equation is established as the state equation, which incorporates the output of angular rate gyroscope. Therefore, the measurement equation can be established with sun direction vector from the sun sensor and speed observation from the speedometer. The gyro continuous output ensures the algorithm real-time operation. Finally, we use the dual-EKF method to solve the system equations. Simulation results show that the proposed method can acquire the rover position and heading information in real time and greatly improve the navigation accuracy. Our method overcomes the disadvantage of the cumulative error in inertial navigation.
The effects of frequency-dependent quasar evolution on the celestial reference frame
Shabala, Stanislav; McCallum, Jamie; Titov, Oleg; Blanchard, Jay; Lovell, Jim; Watson, Christopher
2013-01-01
We examine the relationship between source position stability and astrophysical properties of radio-loud quasars making up the International Celestial Reference Frame. We construct light curves for 95 most frequently observed ICRF2 quasars at both the geodetic VLBI observing bands. Because the appearance of new quasar components corresponds to an increase in quasar flux density, these light curves allow us to probe source structure on sub-100 microarcsecond scales, much smaller than conventional VLBI imaging. Flux density monitoring also allows us to trace the evolution of quasar structure. We test how source position stability depends on three astrophysical parameters: (1) Flux density variability at X-band; (2) Time lag between S and X-band light curves; (3) Spectral index rms, defined as the variability in the ratio between S and X-band flux densities. We find that small (<0.15 years) time lags between S and X-band light curves and low (<0.10) spectral index variability are excellent indicators of po...
Asymptotic theory of the motion of celestial bodies in the atmosphere
Stulov, V. P.
2004-04-01
At a large entry velocity of celestial bodies into the atmosphere, a mass-loss parameter β= σVe2/2 ( σ is the ablation coefficient) is very large. So, for some versions of the 1908 Tunguska event parameters, one has β=5-25. In the case of comet Shoemaker-Levy 9 fragments entry into Jupiter, the parameter β is 75-100. Some stations of European Fireball Network have observed at May, June 1997 two bolides, for which β was estimated as 150 and 40. Therefore, the limiting theory for meteoroid motion in the atmosphere is developed. The solution of meteoric physics equations depends on two (single body) or three parameters (splitting body), and β is among them as argument of some special functions. The asymptotic limit of the solution at β≫1 looks like changing meteoroid mass from entry value to zero at constant velocity. This limit for a single body was compared with observations in May, June 1997 in Czech Republic, and good agreement was achieved. Ultimate models with fragmentation are necessary to understand some real features of large-scale events. So, results of this work show that for large bodies such as Tunguska space body and comet Shoemaker-Levy 9 fragments, we should discuss a motion of gaseous volume after finishing ablation at almost entry velocity. Probably, the big forest fall in 1908 in Siberia and plumes in 1994 on Jupiter are results of such gas jets.
Weiland, J L; Hill, R S; Wollack, E; Hinshaw, G; Greason, M R; Jarosik, N; Page, L; Bennett, C L; Dunkley, J; Gold, B; Halpern, M; Kogut, A; Komatsu, E; Larson, D; Limon, M; Meyer, S S; Nolta, M R; Smith, K M; Spergel, D N; Tucker, G S; Wright, E L
2010-01-01
We present WMAP seven-year observations of bright sources which are often used as calibrators at microwave frequencies. Ten objects are studied in five frequency bands (23 - 94 GHz): the outer planets (Mars, Jupiter, Saturn, Uranus and Neptune) and five fixed celestial sources (Cas A, Tau A, Cyg A, 3C274 and 3C58). The seven-year analysis of Jupiter provides temperatures which are within 1-sigma of the previously published WMAP five-year values, with slightly tighter constraints on variability with orbital phase, and limits (but no detections) on linear polarization. Scaling factors are provided which, when multiplied by the Wright Mars thermal model predictions at 350 micron, reproduce WMAP seasonally averaged observations of Mars within ~2%. An empirical model is described which fits brightness variations of Saturn due to geometrical effects and can be used to predict the WMAP observations to within 3%. Seven-year mean temperatures for Uranus and Neptune are also tabulated. Uncertainties in Uranus temperatu...
Non-parametric PSF estimation from celestial transit solar images using blind deconvolution
Gonzalez, Adriana; Jacques, Laurent
2016-01-01
Context: Characterization of instrumental effects in astronomical imaging is important in order to extract accurate physical information from the observations. Optics are never perfect and the non-ideal path through the telescope is usually represented by the convolution of an ideal image with a Point Spread Function (PSF). Other sources of noise (read-out, Photon) also contaminate the image acquisition process. The problem of estimating both the PSF filter and a denoised image is called blind deconvolution and is ill-posed. Aims: We propose a blind deconvolution scheme that relies on image regularization. Contrarily to most methods presented in the literature, it does not assume a parametric model of the PSF and can thus be applied to any telescope. Methods: Our scheme uses a wavelet analysis image prior model and weak assumptions on the PSF filter's response. We use the observations from a celestial body transit where such object can be assumed to be a black disk. Such constraints limits the interchangeabil...
Initial deep LOFAR observations of Epoch of Reionization windows: I. The North Celestial Pole
Yatawatta, S; Brentjens, M A; Labropoulos, P; Pandey, V N; Kazemi, S; Zaroubi, S; Koopmans, L V E; Offringa, A R; Jelic, V; Rubi, O Martinez; Veligatla, V; Wijnholds, S J; Brouw, W N; Bernardi, G; Ciardi, B; Daiboo, S; Harker, G; Mellema, G; Schaye, J; Thomas, R; Vedantham, H; Chapman, E; Abdalla, F B; Alexov, A; Anderson, J; Avruch, I M; Batejat, F; Bell, M E; Bell, M R; Bentum, M; Best, P; Bonafede, A; Bregman, J; Breitling, F; van de Brink, R H; Broderick, J W; Bruggen, M; Conway, J; de Gasperin, F; de Geus, E; Duscha, S; Falcke, H; Fallows, R A; Ferrari, C; Frieswijk, W; Garrett, M A; Griessmeier, J M; Gunst, A W; Hassall, T E; Hessels, J W T; Hoeft, M; Iacobelli, M; Juette, E; Karastergiou, A; Kondratiev, V I; Kramer, M; Kuniyoshi, M; Kuper, G; van Leeuwen, J; Maat, P; Mann, G; McKean, J P; Mevius, M; Mol, J D; Munk, H; Nijboer, R; Noordam, J E; Norden, M J; Orru, E; Paas, H; Pandey-Pommier, M; Pizzo, R; Polatidis, A G; Reich, W; Rottgering, H J A; Sluman, J; Smirnov, O; Stappers, B; Tagger, M; Tang, Y; Tasse, C; ter Veen, S; Vermeulen, R; van Weeren, R J; Wise, M; Wucknitz, O; Zarka, P
2013-01-01
The aim of the LOFAR Epoch of Reionization (EoR) project is to detect the spectral fluctuations of the redshifted HI 21cm signal. This signal is weaker by several orders of magnitude than the astrophysical foreground signals and hence, in order to achieve this, very long integrations, accurate calibration for stations and ionosphere and reliable foreground removal are essential. One of the prospective observing windows for the LOFAR EoR project will be centered at the North Celestial Pole (NCP). We present results from observations of the NCP window using the LOFAR highband antenna (HBA) array in the frequency range 115 MHz to 163 MHz. The data were obtained in April 2011 during the commissioning phase of LOFAR. We used baselines up to about 30 km. With about 3 nights, of 6 hours each, effective integration we have achieved a noise level of about 100 microJy/PSF in the NCP window. Close to the NCP, the noise level increases to about 180 microJy/PSF, mainly due to additional contamination from unsubtracted nea...
The lizard celestial compass detects linearly polarized light in the blue.
Beltrami, Giulia; Parretta, Antonio; Petrucci, Ferruccio; Buttini, Paola; Bertolucci, Cristiano; Foà, Augusto
2012-09-15
The present study first examined whether ruin lizards, Podarcis sicula, are able to orientate using plane-polarized light produced by an LCD screen. Ruin lizards were trained and tested indoors, inside a hexagonal Morris water maze positioned under an LCD screen producing white polarized light with a single E-vector, which provided an axial cue. White polarized light did not include wavelengths in the UV. Lizards orientated correctly either when tested with E-vector parallel to the training axis or after 90 deg rotation of the E-vector direction, thus validating the apparatus. Further experiments examined whether there is a preferential region of the light spectrum to perceive the E-vector direction of polarized light. For this purpose, lizards reaching learning criteria under white polarized light were subdivided into four experimental groups. Each group was tested for orientation under a different spectrum of plane-polarized light (red, green, cyan and blue) with equalized photon flux density. Lizards tested under blue polarized light orientated correctly, whereas lizards tested under red polarized light were completely disoriented. Green polarized light was barely discernible by lizards, and thus insufficient for a correct functioning of their compass. When exposed to cyan polarized light, lizard orientation performances were optimal, indistinguishable from lizards detecting blue polarized light. Overall, the present results demonstrate that perception of linear polarization in the blue is necessary - and sufficient - for a proper functioning of the sky polarization compass of ruin lizards. This may be adaptively important, as detection of polarized light in the blue improves functioning of the polarization compass under cloudy skies, i.e. when the alternative celestial compass based on detection of the sun disk is rendered useless because the sun is obscured by clouds.
Belda, Santiago; Heinkelmann, Robert; Ferrándiz, José M.; Nilsson, Tobias; Schuh, Harald
2017-02-01
Precise transformation between the celestial reference frames (CRF) and terrestrial reference frames (TRF) is needed for many purposes in Earth and space sciences. According to the Global Geodetic Observing System (GGOS) recommendations, the accuracy of positions and stability of reference frames should reach 1 mm and 0.1 mm year^{-1}, and thus, the Earth Orientation Parameters (EOP) should be estimated with similar accuracy. Different realizations of TRFs, based on the combination of solutions from four different space geodetic techniques, and CRFs, based on a single technique only (VLBI, Very Long Baseline Interferometry), might cause a slow degradation of the consistency among EOP, CRFs, and TRFs (e.g., because of differences in geometry, orientation and scale) and a misalignment of the current conventional EOP series, IERS 08 C04. We empirically assess the consistency among the conventional reference frames and EOP by analyzing the record of VLBI sessions since 1990 with varied settings to reflect the impact of changing frames or other processing strategies on the EOP estimates. Our tests show that the EOP estimates are insensitive to CRF changes, but sensitive to TRF variations and unmodeled geophysical signals at the GGOS level. The differences between the conventional IERS 08 C04 and other EOP series computed with distinct TRF settings exhibit biases and even non-negligible trends in the cases where no differential rotations should appear, e.g., a drift of about 20 μ as year^{-1 }in y_{pol } when the VLBI-only frame VTRF2008 is used. Likewise, different strategies on station position modeling originate scatters larger than 150 μ as in the terrestrial pole coordinates.
Non-parametric PSF estimation from celestial transit solar images using blind deconvolution
González, Adriana; Delouille, Véronique; Jacques, Laurent
2016-01-01
Context: Characterization of instrumental effects in astronomical imaging is important in order to extract accurate physical information from the observations. The measured image in a real optical instrument is usually represented by the convolution of an ideal image with a Point Spread Function (PSF). Additionally, the image acquisition process is also contaminated by other sources of noise (read-out, photon-counting). The problem of estimating both the PSF and a denoised image is called blind deconvolution and is ill-posed. Aims: We propose a blind deconvolution scheme that relies on image regularization. Contrarily to most methods presented in the literature, our method does not assume a parametric model of the PSF and can thus be applied to any telescope. Methods: Our scheme uses a wavelet analysis prior model on the image and weak assumptions on the PSF. We use observations from a celestial transit, where the occulting body can be assumed to be a black disk. These constraints allow us to retain meaningful solutions for the filter and the image, eliminating trivial, translated, and interchanged solutions. Under an additive Gaussian noise assumption, they also enforce noise canceling and avoid reconstruction artifacts by promoting the whiteness of the residual between the blurred observations and the cleaned data. Results: Our method is applied to synthetic and experimental data. The PSF is estimated for the SECCHI/EUVI instrument using the 2007 Lunar transit, and for SDO/AIA using the 2012 Venus transit. Results show that the proposed non-parametric blind deconvolution method is able to estimate the core of the PSF with a similar quality to parametric methods proposed in the literature. We also show that, if these parametric estimations are incorporated in the acquisition model, the resulting PSF outperforms both the parametric and non-parametric methods.
Joint analysis of celestial pole offset and free core nutation series
Malkin, Zinovy
2016-10-01
Three combined celestial pole offset (CPO) series computed at the Paris Observatory (C04), the United States Naval Observatory (USNO), and the International VLBI Service for Geodesy and Astrometry (IVS), as well as six free core nutation (FCN) models, were compared from different perspectives, such as stochastic and systematic differences, and FCN amplitude and phase variations. The differences between the C04 and IVS CPO series were mostly stochastic, whereas a low-frequency bias at the level of several tens of μ as was found between the C04 and USNO CPO series. The stochastic differences between the C04 and USNO series became considerably smaller when computed at the IVS epochs, which can indicate possible problems with the interpolation of the IVS data at the midnight epochs during the computation of the C04 and USNO series. The comparison of the FCN series showed that the series computed with similar window widths of 1.1-1.2 years were close to one another at a level of 10-20 μ as, whereas the differences between these series and the series computed with a larger window width of 4 and 7 years reached 100 μ as. The dependence of the FCN model on the underlying CPO series was investigated. The RMS differences between the FCN models derived from the C04, USNO, and IVS CPO series were at a level of approximately 15 μ as, which was considerably smaller than the differences among the CPO series. The analysis of the differences between the IVS, C04, and USNO CPO series suggested that the IVS series would be preferable for both precession-nutation and FCN-related studies.
Belda, Santiago; Heinkelmann, Robert; Ferrándiz, José M.; Nilsson, Tobias; Schuh, Harald
2016-08-01
Precise transformation between the celestial reference frames (CRF) and terrestrial reference frames (TRF) is needed for many purposes in Earth and space sciences. According to the Global Geodetic Observing System (GGOS) recommendations, the accuracy of positions and stability of reference frames should reach 1 mm and 0.1 mm year^{-1} , and thus, the Earth Orientation Parameters (EOP) should be estimated with similar accuracy. Different realizations of TRFs, based on the combination of solutions from four different space geodetic techniques, and CRFs, based on a single technique only (VLBI, Very Long Baseline Interferometry), might cause a slow degradation of the consistency among EOP, CRFs, and TRFs (e.g., because of differences in geometry, orientation and scale) and a misalignment of the current conventional EOP series, IERS 08 C04. We empirically assess the consistency among the conventional reference frames and EOP by analyzing the record of VLBI sessions since 1990 with varied settings to reflect the impact of changing frames or other processing strategies on the EOP estimates. Our tests show that the EOP estimates are insensitive to CRF changes, but sensitive to TRF variations and unmodeled geophysical signals at the GGOS level. The differences between the conventional IERS 08 C04 and other EOP series computed with distinct TRF settings exhibit biases and even non-negligible trends in the cases where no differential rotations should appear, e.g., a drift of about 20 μ as year^{-1 } in y_{pol } when the VLBI-only frame VTRF2008 is used. Likewise, different strategies on station position modeling originate scatters larger than 150 μ as in the terrestrial pole coordinates.
Theodossiou, Efstratios; Manimanis, Vassilios N.; Dimitrijević, Milan S.; Mantarakis, Petros
In this article we consider the role of the three principal celestial bodies, the Earth (Gaia), the Sun (Helios) and the Moon (Selene), as well as the Sky (Ouranos) in the ancient Greek cosmogony. This is done by the analysis of antique Greek texts like Orphic Hymns and the literary remains of the writers and philosophers like Aeschylus, (Pseudo) Apollodorus, Apollonius Rhodius, Aristotle, Euripides, Hesiod, Homer, Hyginus, Nonnus, Pausanias, Pindar and Sophocles, as well as by the analysis of texts of Roman writers like Cicero, Ovid and Pliny.
Quantum and Post-Newtonian Effects in the Anomalistic Period and the Mean Motion of Celestial Bodies
Haranas, Ioannis; Gkigkitzis, Ioannis; Kotsireas, Ilias
2015-01-01
We study the motion of a secondary celestial body under the influence of the corrected gravitational force of a primary. We study the effect of quantum and relativistic corrections to the gravitational potential of a primary body acting on the orbiting body. More specifically, two equations are derived to approximate the perigee/perihelion/periastron time rate of change and its total variation over one revolution (i.e., the difference between the anomalistic period and the Keplerian period) under the influence of the quantum as well as post- Newtonian accelerations. Numerical results have been obtained for the artificial Earth satellite Molnya, Mercury, and, finally, the for the HW Vir c, planetary companion.
Sheikh, Suneel I. (Inventor); Hisamoto, Chuck (Inventor); Arzoumanian, Zaven (Inventor)
2015-01-01
A method and system for spacecraft navigation using distant celestial gamma-ray bursts which offer detectable, bright, high-energy events that provide well-defined characteristics conducive to accurate time-alignment among spatially separated spacecraft. Utilizing assemblages of photons from distant gamma-ray bursts, relative range between two spacecraft can be accurately computed along the direction to each burst's source based upon the difference in arrival time of the burst emission at each spacecraft's location. Correlation methods used to time-align the high-energy burst profiles are provided. The spacecraft navigation may be carried out autonomously or in a central control mode of operation.
Institute of Scientific and Technical Information of China (English)
LI Guoqing; ZONG Haifeng; ZHANG Qingyun
2011-01-01
Variation in length of day of the Earth (LOD equivalent to the Earth's rotation rate) versus change in atmospheric geopotential height fields and astronomical parameters were analyzed for the years 1962-2006.This revealed that there is a 27.3-day and an average 13.6-day periodic oscillation in LOD and atmospheric pressure fields following lunar revolution around the Earth. Accompanying the alternating change in celestial gravitation forcing on the Earth and its atmosphere, the Earth's LOD changes from minimum to maximum,then to minimum. and the atmospheric geopotential height fields in the tropics oscillate from low to high,then to low. The 27.3-day and average 13.6-day periodic atmospheric oscillation in the tropics is proposed to be a type of strong atmospheric tide, excited by celestial gravitation forcing. A formula for a Tidal Index was derived to estimate the strength of the celestial gravitation forcing, and a high degree of correlation was found between the Tidal Index determined by astronomical parameters, LOD, and atmospheric geopotential height. The reason for the atmospheric tide is periodic departure of the lunar orbit from the celestial equator during lunar revolution around the Earth. The alternating asymmetric change in celestial gravitation forcing on the Earth and its atmosphere produces a "modulation" to the change in the Earth's LOD and atmospheric pressure fields.
Wang, Xin; Gao, Jun; Fan, Zhiguo; Roberts, Nicholas W.
2016-06-01
We present a computationally inexpensive analytical model for simulating celestial polarization patterns in variable conditions. We combine both the singularity theory of Berry et al (2004 New J. Phys. 6 162) and the intensity model of Perez et al (1993 Sol. Energy 50 235-245) such that our single model describes three key sets of data: (1) the overhead distribution of the degree of polarization as well as the existence of neutral points in the sky; (2) the change in sky polarization as a function of the turbidity of the atmosphere; and (3) sky polarization patterns as a function of wavelength, calculated in this work from the ultra-violet to the near infra-red. To verify the performance of our model we generate accurate reference data using a numerical radiative transfer model and statistical comparisons between these two methods demonstrate no significant difference in almost all situations. The development of our analytical model provides a novel method for efficiently calculating the overhead skylight polarization pattern. This provides a new tool of particular relevance for our understanding of animals that use the celestial polarization pattern as a source of visual information.
Yan, Kun
2007-04-01
In this paper, by discussing the basic hypotheses about the continuous orbit and discrete orbit in two research directions of the background medium theory for celestial body motion, the concrete equation forms and their summary of the theoretic frame of celestial body motion are introduced. Future more, by discussing the general form of Binet's equation of celestial body motion orbit and it's solution of the advance of the perihelion of planets, the relations and differences between the continuous orbit theory and Newton's gravitation theory and Einstein's general relativity are given. And by discussing the fractional-dimension expanded equation for the celestial body motion orbits, the concrete equations and the prophesy data of discrete orbit or stable orbits of celestial bodies which included the planets in the Solar system, satellites in the Uranian system, satellites in the Earth system and satellites obtaining the Moon obtaining from discrete orbit theory are given too. Especially, as the preliminary exploration and inference to the gravitation curve of celestial bodies in broadly range, the concept for the ideal black hole with trend to infinite in mass density difficult to be formed by gravitation only is explored. By discussing the position hypothesis of fractional-dimension derivative about general function and the formula form the hypothesis of fractional-dimension derivative about power function, the concrete equation formulas of fractional-dimension derivative, differential and integral are described distinctly further, and the difference between the fractional-dimension derivative and the fractional-order derivative are given too. Subsequently, the concrete forms of measure calculation equations of self-similar fractal obtaining by based on the definition of form in fractional-dimension calculus about general fractal measure are discussed again, and the differences with Hausdorff measure method or the covering method at present are given. By applying
Komovkin, S. V.; Lavrenov, S. M.; Tuchin, A. G.; Tuchin, D. A.; Yaroshevsky, V. S.
2016-12-01
The article describes a model of the two-way measurements of radial velocity based on the Doppler effect. The relations are presented for the instantaneous value of the increment range at the time of measurement and the radial velocity of the mid-dimensional interval. The compensation of methodological errors of interpretation of the two-way Doppler measurements is considered.
Kochemasov, G. G.
2008-09-01
The wave planetology [1, 2, 3 & others] declares in its first theorem that all celestial bodies are dichotomous. This is a result of a warping action of the fundamental wave (wave 1 long 2πR where R is a body radius) that appears in any body due to its movement in non-round (elliptical, parabolic) keplerian orbits with periodically changing accelerations. Having a standing character and four crossing directions in rotating bodies (but all bodies rotate!) these waves inevitably press in one hemisphere and bulge out the opposite one tending to impose on a body convexo-concave shape. This shape is leveled out in larger bodies due to enhanced gravity but is clearly observed in smaller ones with diminished gravity. Still, in the larger bodies as, for an example, in Earth the tectonic dichotomy is expressed as an opposition of the subsided western Pacific hemisphere and the uplifted eastern continental hemisphere. At Mars even sharper dichotomy is in the north-south direction. Small bodies (normally less than 400-500 km across) notwithstanding their type (asteroids, comets, satellites), size and composition (stones, metals, ices) are flattened and bended by the fundamental wave. That is why all asteroids in the main asteroid belt have an oblong shape what was established rather long ago but never was properly explained. Now a number of small satellites is observed by Cassini spacecraft in the saturnian system that makes together with jovian and martian small satellites a representative group for comparisons. In the figures below are shown asteroids, satellites and a comet arranged in a row of increasing sizes. They all are flattened except the largest in the row Enceladus (505 km) and bended tending to acquire a convexo-concave shape. Asteroids: Itokawa (0.5 km long), Eros (33 km, PIA03111). Satellites: Calypso (22 km, PIA07633), Atlas (32 km, PIA08233), Prometheus (102 km, PIA08192), Hyperion (350 km, PIA06645), Enceladus (505 km, PIA08258, comet-like behaviour). Comet
Lanfranchi, G. B.
2011-06-01
For Ancient Mesopotamians, astronomical phenomena were signs signifying the gods' judgment on human behaviour. Mesopotamian scholars studied celestial phenomena for understanding the gods' will, and strongly developed astrology. From the 8th to the 6th century BC Assyrian and Babylonian astronomers achieved the ability to predict solar and lunar eclipses, and the planets' movements through mathematical calculations. Predictability of astral phenomena solicited the awareness that they are all regular, and that the universe is governed by an eternal, immutable order fixed at its very beginning. This finally favoured the idea that the cosmic order depended on the will of one god only, displacing polytheism in favour of monotheism; and astrology lost its religious importance as a mean to know the divine will.
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Satellite orbits have been routinely used to produce models of the Earth’s gravity field. In connection with such productions, the partial derivatives of a satellite orbit with respect to the force parameters to be determined, namely, the unknown harmonic coefficients of the gravitational model, have been first computed by setting the initial values of partial derivatives to zero. In this note, we first design some simple mathematical examples to show that setting the initial values of partial derivatives to zero is generally erroneous mathematically. We then prove that it is prohibited physically. In other words, set-ting the initial values of partial derivatives to zero violates the physics of motion of celestial bodies.
Institute of Scientific and Technical Information of China (English)
XU PeiLiang
2009-01-01
Satellite orbits have been routinely used to produce models of the Earth's gravity field. In connection with such productions, the partial derivatives of a satellite orbit with respect to the force parameters to be determined, namely, the unknown harmonic coefficients of the gravitational model, have been first computed by setting the initial values of partial derivatives to zero. In this note, we first design some simple mathematical examples to show that setting the initial values of partial derivatives to zero is generally erroneous mathematically. We then prove that it is prohibited physically. In other words, set-ting the initial values of partial derivatives to zero violates the physics of motion of celestial bodies.
Hartog, J P Den
1961-01-01
First published over 40 years ago, this work has achieved the status of a classic among introductory texts on mechanics. Den Hartog is known for his lively, discursive and often witty presentations of all the fundamental material of both statics and dynamics (and considerable more advanced material) in new, original ways that provide students with insights into mechanical relationships that other books do not always succeed in conveying. On the other hand, the work is so replete with engineering applications and actual design problems that it is as valuable as a reference to the practicing e
Intrinsic electromagnetic variability in celestial objects containing rapidly spinning black holes
Zhang, Fan
2016-01-01
Analytical studies have raised the concern that a mysterious expulsion of magnetic field lines by a rapidly-spinning black hole (dubbed the black hole Meissner effect) would shut down the Blandford-Znajek process and quench the jets of active galactic nuclei and microquasars. This effect is however not seen observationally or in numerical simulations. Previous attempts at reconciling the predictions with observations have proposed several mechanisms to evade the Meissner effect. In this paper, we identify a new evasion mechanism and discuss its observational significance. Specifically, we show that the breakdown of stationarity is sufficient to remove the expulsion of the magnetic field at all multipole orders, and that the associated temporal variation is likely turbulent due to the existence of efficient mechanisms for sharing energy across different modes. Such an intrinsic (as opposed to being driven externally by, e.g., changes in the accretion rate) variability of the electromagnetic field can produce t...
Jacobs, Christopher
2015-08-01
ICRF-3 seeks to improve upon the highly successful ICRF-2. Our goals are to improve the precision, spatial and frequency coverage relative to the ICRF-2 by 2018. This date is driven by the desire to create radio frames that are ready for comparison with the Gaia optical frame.Several specific actions are underway. A collaboration to improve at S/X-band precision of the Very Long Baseline Array (VLBA) Calibrator Survey's ~2200 sources, which are typically 5 times less precise than the rest of the ICRF-2, is bearing fruit and is projected to yield a factor of 3 improvement in precision. S/X-band southern hemisphere precision improvements are underway with observations using southern antennas such as the AuScope, Warkworth, and HartRAO, South Africa.We also seek to improve radio frequency coverage with X/Ka-band and K-band work. An X/Ka frame of 660 sources now has full sky coverage from the addition of a 2nd southern station in Argentina which is strengthening the southern hemisphere in general. The X/Ka-band frame's precision is now comparable to the ICRF-2 for the 530 sources in common. A K-band collaboration has formed with similar coverage and southern precision goals. By the time of this meeting, we expect K-band to complete full sky coverage with south polar cap observations and to improve spatial density north of -30 deg declination with VLBA observations.On the analysis front, special attention is being given to combination techniques both of Very Long Baseline Interferometry (VLBI) frames and of multiple data types. Consistency of the Celestial Reference Frame (CRF) with the Terrestrial Reference Frame (TRF) and Earth Oreintation Parameters (EOP) is another area of concern. Comparison of celestial frame solutions from various groups is underway in order to identify and correct systematic errors. We will discuss evidence emerging for 100 µas zonal errors in the ICRF2 in the declination range from 0 to -30 deg.Finally, work is underway to identify and
INTRINSIC ELECTROMAGNETIC VARIABILITY IN CELESTIAL OBJECTS CONTAINING RAPIDLY SPINNING BLACK HOLES
Energy Technology Data Exchange (ETDEWEB)
Zhang, Fan, E-mail: fnzhang@bnu.edu.cn [Gravitational Wave and Cosmology Laboratory, Department of Astronomy, Beijing Normal University, Beijing 100875 (China); Department of Physics and Astronomy, West Virginia University, P.O. Box 6315, Morgantown, WV 26506 (United States)
2016-02-10
Analytical studies have raised the concern that a mysterious expulsion of magnetic field lines by a rapidly spinning black hole (dubbed the black hole Meissner effect) would shut down the Blandford–Znajek process and quench the jets of active galactic nuclei and microquasars. This effect is, however, not seen observationally or in numerical simulations. Previous attempts at reconciling the predictions with observations have proposed several mechanisms to evade the Meissner effect. In this paper, we identify a new evasion mechanism and discuss its observational significance. Specifically, we show that the breakdown of stationarity is sufficient to remove the expulsion of the magnetic field at all multipole orders, and that the associated temporal variation is likely turbulent because of the existence of efficient mechanisms for sharing energy across different modes. Such an intrinsic (as opposed to being driven externally by, e.g., changes in the accretion rate) variability of the electromagnetic field can produce the recorded linear correlation between microvariability amplitudes and mean fluxes, help create magnetic randomness and seed sheared magnetic loops in jets, and lead to a better theoretical fit to the X-ray microvariability power spectral density.
The Great Celestial Numbers - The Infinitely Big and The Infinitely Small
Teodorani, M.
2009-11-01
This book is a travel that brings the reader to penetrate dimensionally the infinitely small and the infinitely large in the Universe, ranging from quarks to galaxies, and to compare these extreme numbers with the numbers that people encounters in normal life here on Earth. Several numerical examples are illustrated all over the text in a sort of scientific orienteering that describes dimensionally the realms of space, time and energy. The last part of the book shows how all spatial and temporal dimensions disappear when the mechanism of quantum entanglement is considered.
Menanteau, Felipe; Barrientos, L Felipe; Battaglia, Nicholas; Bond, J Richard; Crichton, Devin; Das, Sudeep; Devlin, Mark J; Dünner, Rolando; Gralla, Megan; Hajian, Amir; Hasselfield, Matthew; Hilton, Matt; Hincks, Adam D; Hughes, John P; Infante, Leopoldo; Kosowsky, Arthur; Marriage, Tobias A; Marsden, Danica; Moodley, Kavilan; Niemack, Michael D; Nolta, Michael R; Page, Lyman A; Partridge, Bruce; Reese, Erik D; Schmitt, Benjamin L; Sievers, Jon; Spergel, David N; Staggs, Suzanne T; Switzer, Eric; Wollack, Edward J
2012-01-01
We present the optical and X-ray properties of 68 galaxy clusters selected via the Sunyaev-Zel'dovich Effect at 148 GHz by the Atacama Cosmology Telescope (ACT). Our sample, from an area of 504 square degrees centered on the celestial equator, is divided into two regions. The main region uses 270 square degrees of the ACT survey that overlaps with the co-added ugriz imaging from the Sloan Digital Sky Survey (SDSS) over Stripe 82 plus additional near-infrared pointed observations with the Apache Point Observatory 3.5-meter telescope. We confirm a total of 49 clusters to z~1.3, of which 22 (all at z>0.55) are new discoveries. For the second region the regular-depth SDSS imaging allows us to confirm 19 more clusters up to z~0.7, of which 10 systems are new. We present the optical richness, photometric redshifts, and separation between the SZ position and the brightest cluster galaxy (BCG). We find no significant offset between the cluster SZ centroid and BCG location and a weak correlation between optical richne...
Stewart, A J; Broderick, J W; Hassall, T E; Muñoz-Darias, T; Rowlinson, A; Swinbank, J D; Staley, T D; Molenaar, G J; Scheers, B; Grobler, T L; Pietka, M; Heald, G; McKean, J P; Bell, M E; Bonafede, A; Breton, R P; Carbone, D; Cendes, Y; Clarke, A O; Corbel, S; de Gasperin, F; Eislöffel, J; Falcke, H; Ferrari, C; Grießmeier, J -M; Hardcastle, M J; Heesen, V; Hessels, J W T; Horneffer, A; Iacobelli, M; Jonker, P; Karastergiou, A; Kokotanekov, G; Kondratiev, V I; Kuniyoshi, M; Law, C J; van Leeuwen, J; Markoff, S; Miller-Jones, J C A; Mulcahy, D; Orru, E; Pandey-Pommier, M; Pratley, L; Rol, E; Röttgering, H J A; Scaife, A M M; Shulevski, A; Sobey, C A; Stappers, B W; Tasse, C; van der Horst, A J; van Velzen, S; van Weeren, R J; Wijers, R A M J; Wijnands, R; Wise, M; Zarka, P; Alexov, A; Anderson, J; Asgekar, A; Avruch, I M; Bentum, M J; Bernardi, G; Best, P; Breitling, F; Brüggen, M; Butcher, H R; Ciardi, B; Conway, J E; Corstanje, A; de Geus, E; Deller, A; Duscha, S; Frieswijk, W; Garrett, M A; Gunst, A W; van Haarlem, M P; Hoeft, M; Hörandel, J; Juette, E; Kuper, G; Loose, M; Maat, P; McFadden, R; McKay-Bukowski, D; Moldon, J; Munk, H; Norden, M J; Paas, H; Polatidis, A G; Schwarz, D; Sluman, J; Smirnov, O; Steinmetz, M; Thoudam, S; Toribio, M C; Vermeulen, R; Vocks, C; Wijnholds, S J; Wucknitz, O; Yatawatta, S
2015-01-01
We present the results of a four-month campaign searching for low-frequency radio transients near the North Celestial Pole with the Low-Frequency Array (LOFAR), as part of the Multifrequency Snapshot Sky Survey (MSSS). The data were recorded between 2011 December and 2012 April and comprised 2149 11-minute snapshots, each covering 175 deg^2. We have found one convincing candidate astrophysical transient, with a duration of a few minutes and a flux density at 60 MHz of 15-25 Jy. The transient does not repeat and has no obvious optical or high-energy counterpart, as a result of which its nature is unclear. The detection of this event implies a transient rate at 60 MHz of 3.9 (+14.7, -3.7) x 10^-4 day^-1 deg^-2, and a transient surface density of 1.5 x 10^-5 deg^-2, at a 7.9-Jy limiting flux density and ~10-minute time-scale. The campaign data were also searched for transients at a range of other time-scales, from 0.5 to 297 min, which allowed us to place a range of limits on transient rates at 60 MHz as a funct...
Chester, W
1979-01-01
When I began to write this book, I originally had in mind the needs of university students in their first year. May aim was to keep the mathematics simple. No advanced techniques are used and there are no complicated applications. The emphasis is on an understanding of the basic ideas and problems which require expertise but do not contribute to this understanding are not discussed. How ever, the presentation is more sophisticated than might be considered appropri ate for someone with no previous knowledge of the subject so that, although it is developed from the beginning, some previous acquaintance with the elements of the subject would be an advantage. In addition, some familiarity with element ary calculus is assumed but not with the elementary theory of differential equations, although knowledge of the latter would again be an advantage. It is my opinion that mechanics is best introduced through the motion of a particle, with rigid body problems left until the subject is more fully developed. Howev...
Generalized flyby trajectories around elongated minor celestial bodies as a rotating mass dipole
Institute of Scientific and Technical Information of China (English)
Xiangyuan Zeng; Baodong Fang; Junfeng Li; Yang Yu
2016-01-01
The aim of this paper is to understand the com-mon characteristics of the generalized flyby trajectory around natural elongated bodies. Such flyby trajectories provide a short-term mechanism to clear away vicinal objects or temporally capture ejecta into circling orbits. The gravita-tional potential of elongated bodies is described by a unified approximate model, i.e., the rotating mass dipole which is two point masses connected with a constant massless rod. The energy power is used to illustrate the flyby effect in terms of the instantaneous orbital energy. The essential of the single flyby trajectory is studied analytically, and the relationship between the flyby trajectory and its Jacobi integral is also illustrated. Sample trajectories are given to show the varia-tional trend of the energy increment with respect to different orbital periapsides. The distribution of natural ejecting orbits is presented by varying the parameters of the approximate model.
Institute of Scientific and Technical Information of China (English)
李海林; 吴德伟
2012-01-01
针对航天器自主导航方法不适合高超声速临近空间飞行器的问题，研究了基于非开普勒轨道的高超声速临近空间飞行器自主天文导航方案．论述了基于非开普勒轨道的自主天文导航机理，通过对高超声速临近空间飞行器受力分析，建立了动力学方程；利用矢量倒数法则推导出空间运动方程；设计了基于非开普勒轨道的状态模型和基于星光折射间接敏感地平的观测模型，采用卡尔曼滤波进行了仿真验证．仿真结果表明，基于非开普勒轨道的高超声速临近空间飞行器自主天文导航可达到较高的位置和速度精度．%In allusion to the problem that the aircraft autonomous celestial navigation is not suitable for the near space vehicles with hypersonic speed, an approach of the autonomous celestial navigation of near space vehicles with hypersonic speed based on non-Keplerian orbits is studied. Mechanism of the autonomous celestial navigation based on non-Keplerian is analyzed, and the dynamic equations are developed by analyzing the strength of near space vehicles with hypersonic speed. The space motion equation is educed using the vector derivatives rules. States model based on non-Keplerian orbits and measurement model using the concept of stellar horizon atmospheric refraction are de- signed, and the Kalman filter simulation is adopted. Results show that the autonomous celestial navigation of near space vehicles with hypersonic speed based on non-Keplerian orbits can meet the requirement of high precision for position and velocity, which is important for further research on the near space vehicles with hypersonic speed.
Institute of Scientific and Technical Information of China (English)
王鹏; 张迎春
2015-01-01
为了实现大椭圆轨道(HEO)卫星高精度自主导航，提出一种将直接敏感地平天文导航与全球定位系统(GPS)相结合的组合导航方法.首先，分析卫星轨道��2运动模型及其所受空间摄动，建立卫星轨道动力学模型；然后，分析单一使用天文导航和GPS的优缺点，根据HEO卫星对GPS的可见性，提出在远地点只采用天文导航，而在近地点采用以天文导航为主、适时引入GPS信号进行位速测量辅助修正的方法.通过计算机仿真和结果分析表明了所提出的设计方法导航精度比单一天文导航提高72.4%∼85.6%.%In order to realize autonomous and continuous navigation information outputs for high elliptical orbit(HEO) satellite, new integrated navigation system is proposed based on celestial navigation of directly sensing stellar and global positioning system(GPS) navigation. Firstly, satellite orbit motion model is established on the satellite orbit dynamics��2 model and suffered space perturbation. Moreover, performances of single-use celestial navigation or GPS are analyzed. When the satellite is near the apogee, observation system is established by using only celestial navigation. When the satellite is near the perigee, the estimate covariance is revised through incoming GPS signal to improve the celestial navigation estimate. The autonomous navigation system is designed and simulating. The results of computer simulation show that the navigation accuracy is improved by 72.4%∼85.6%compared with the celestial navigation method.
New celestial reference system
Seidelmann, P. K.; Kaplan, G. H.; van Flandern, T. C.
It is pointed out that the IAU (1976) System of Astronomical Constants, the FK5 and new lunar and planetary theories are being introduced in 1984. The investigation and planning for the transition have revealed the complex interdependencies between observational techniques and the reference systems and their strong link to the rotating and orbiting earth. Details for the conversion to the new system are given. The concepts for a future reference system are developed, based on separating the real motions involved in such a way that observations from various moving platforms can be related to the appropriate coordinate system without involving motions that are not intrinsically involved in the observations. As a consequence, the reference systems determined or used in space, while affected by aberration and parallax, would logically be defined with no dependence on precession, nutation, polar motion, or Universal Time, all of which are concerned with motions of the earth's surface.
Terrestrial and Celestial Cartography,
1979-05-01
Arizona, Tucson, 1972) 69. Thirteen-Color Photometry of 1380 Bright Stars. H. L. Johnson, and R. I. Mitchell, Revista Mexicana de Astronomia y Astrofisica...1. 299 (1975) 90. A New Michelson Spec trophotometer System. H. L. Johnson, Revista Mexicana de Astronomia y Astrofisica, 2, 219 (1977) 91. An Atlas...of Stellar Spectra. I. H. L. Johnson. Revista Mexicana de Astronomia y Astrofisica, 2, 71 (1977) 92. An Atlas of Stellar Spectra. II. H. L. Johnson
1995-11-01
and headed out into the sunshine of a bright new Monday morning. I was on the way to breakfast at the mess hall a block away. It seemed that it would...He stood on a box and addressed his weary audience through an interpreter. His message was short and to the point: "You are our eternal enemy! You may...afternoon was an eternity . The sun seemed to hang in the sky as if it would never go down. Then, when darkness came, it seemed as if everything had
Energy Technology Data Exchange (ETDEWEB)
Menanteau, Felipe; Hughes, John P. [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Sifon, Cristobal; Barrientos, L. Felipe; Duenner, Rolando; Infante, Leopoldo [Departamento de Astronomia y Astrofisica, Facultad de Fisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile); Battaglia, Nicholas [McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Bond, J. Richard; Hajian, Amir; Hincks, Adam D. [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON M5S 3H8 (Canada); Crichton, Devin; Gralla, Megan; Marriage, Tobias A. [Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218-2686 (United States); Das, Sudeep [High Energy Physics Division, Argonne National Laboratory, 9700 S Cass Avenue, Lemont, IL 60439 (United States); Devlin, Mark J.; Dicker, Simon [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Hasselfield, Matthew [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z4 (Canada); Hilton, Matt [Astrophysics and Cosmology Research Unit, School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal, Durban (South Africa); Kosowsky, Arthur [Physics and Astronomy Department, University of Pittsburgh, 100 Allen Hall, 3941 O' Hara Street, Pittsburgh, PA 15260 (United States); Marsden, Danica [Department of Physics, University of California Santa Barbara, CA 93106 (United States); and others
2013-03-01
We present the optical and X-ray properties of 68 galaxy clusters selected via the Sunyaev-Zel'dovich (SZ) effect at 148 GHz by the Atacama Cosmology Telescope (ACT). Our sample, from an area of 504 deg{sup 2} centered on the celestial equator, is divided into two regions. The main region uses 270 deg{sup 2} of the ACT survey that overlaps with the co-added ugriz imaging from the Sloan Digital Sky Survey (SDSS) over Stripe 82 plus additional near-infrared pointed observations with the Apache Point Observatory 3.5 m telescope. We confirm a total of 49 clusters to z Almost-Equal-To 1.3, of which 22 (all at z > 0.55) are new discoveries. For the second region, the regular-depth SDSS imaging allows us to confirm 19 more clusters up to z Almost-Equal-To 0.7, of which 10 systems are new. We present the optical richness, photometric redshifts, and separation between the SZ position and the brightest cluster galaxy (BCG). We find no significant offset between the cluster SZ centroid and BCG location and a weak correlation between optical richness and SZ-derived mass. We also present X-ray fluxes and luminosities from the ROSAT All Sky Survey which confirm that this is a massive sample. One of the newly discovered clusters, ACT-CL J0044.4+0113 at z = 1.1 (photometric), has an integrated XMM-Newton X-ray temperature of kT{sub X} = 7.9 {+-} 1.0 keV and combined mass of M {sub 200a} = 8.2{sup +3.3} {sub -2.5} Multiplication-Sign 10{sup 14} h {sup -1} {sub 70} M {sub Sun }, placing it among the most massive and X-ray-hot clusters known at redshifts beyond z = 1. We also highlight the optically rich cluster ACT-CL J2327.4-0204 (RCS2 2327) at z = 0.705 (spectroscopic) as the most significant detection of the whole equatorial sample with a Chandra-derived mass of M {sub 200a} = 1.9{sup +0.6} {sub -0.4} Multiplication-Sign 10{sup 15} h {sup -1} {sub 70} M {sub Sun }, placing it in the ranks of the most massive known clusters like El Gordo and the Bullet Cluster.
Söderlund, I. E.
2011-06-01
This paper explores the relationship of astronomical phenomena and the painted ceiling The Glorious Deeds of Swedish Kings executed around 1694-1696 by the Swedish court painter David Klöcker Ehrenstrahl in the Royal manor Drottningholm, outside Stockholm. The central theme of the painting is how "Reputation" brings the renown of the valour of the Swedish kings to the stars. When Galileo dedicated the moons of Jupiter to the Medici's he used an already established tradition of likening prominent people to celestial phenomena. This paper explores why motifs related to the stars and heavens was considered to be so suitable in the court context in early modern Europe.
Kolesnikov, E. K.
2016-11-01
This article, like our previous one [1], is devoted to advanced space technology concepts. It evaluates the potential for developing active systems to conduct a remote elemental analysis of surface rocks on an atmosphereless celestial body. The analysis is based on the spectrometry of characteristic X-rays (CXR) artificially excited in the surface soil layer. It has been proposed to use an electron beam injected from aboard a spacecraft orbiting the celestial body (or moving in a flyby trajectory) to excite the CXR elements contained in surface rocks. The focus is on specifying technical requirements to the parameters of payloads for a global mapping of the composition of lunar rocks from aboard of a low-orbiting lunar satellite. This article uses the results obtained in [2], our first study that shows the potential to develop an active system for a remote elemental analysis of lunar surface rocks using the above method. Although there has been interest in our research on the part of leading national academic institutions and space technology developers in the Soviet Union, the studies were discontinued because of the termination of the Soviet lunar program and the completion of the American Apollo program.
Mueller, T G; Nielbock, M; Lim, T; Teyssier, D; Olberg, M; Klaas, U; Linz, H; Altieri, B; Pearson, C; Bendo, G; Vilenius, E
2013-01-01
Celestial standards play a major role in observational astrophysics. They are needed to characterise the performance of instruments and are paramount for photometric calibration. During the Herschel Calibration Asteroid Preparatory Programme approximately 50 asteroids have been established as far-IR/sub-mm/mm calibrators for Herschel. The selected asteroids fill the flux gap between the sub-mm/mm calibrators Mars, Uranus and Neptune, and the mid-IR bright calibration stars. All three Herschel instruments observed asteroids for various calibration purposes, including pointing tests, absolute flux calibration, relative spectral response function, observing mode validation, and cross-calibration aspects. Here we present newly established models for the four large and well characterized main-belt asteroids (1) Ceres, (2) Pallas, (4) Vesta, and (21) Lutetia which can be considered as new prime flux calibrators. The relevant object-specific properties (size, shape, spin-properties, albedo, thermal properties) are w...
Akhlebininskij, M. Yu.; Konstantinov, M. S.
1992-05-01
The problem of generating trajectories for a flyby of several given celestial bodies moving in Keplerian orbits is solved in a new formulation. It is demonstrated that there exist trajectories along which one vehicle can fly by at least three bodies. A theorem asserting the existence of a trajectory for the flyby of three bodies moving in circular orbits of common radius is formulated and probed. The uniqueness of such trajectories is analyzed. An effective numerical method is proposed for generating trajectories for the flyby of three bodies moving in arbitrary elliptical orbits. The possibilities of the method are illustrated with examples. Questions regarding the insertion of the vehicle into the flyby trajectory are not discussed here.
Energy Technology Data Exchange (ETDEWEB)
Tomeoka, K. (The University of Tokyo, Tokyo (Japan). Faculty of Science)
1992-02-01
The meteoritic studies using high-resolution transmission electron microscopes are in a process of elucidating the problem as to whether the carbon-based chondrite meteorites regarded as initial chemically are the substance resulted from accumulation of solid particles which have had existed in the solar system nebulae, or whether they have had been subjected to any secondary modification after the accumulation. The initial state of the solar system was inferred through considering the latest research results on transforming actions given to these source celestial bodies. The intervention of the water quality transformation as a result of water actions at temperatures as low as associating no loss in volatile elements has been elucidated from the researches on micro-structures in a substance contained in the carbon-based chondrite. As to at what stage the water quality transformation has taken place, a view that its timing is after the formation of the base celestial bodies is predominant. A consideration was given on what the first celestial body integrated from a solar system nebula was like using a model presenting the transforming actions on the carbon-based chondrite celestial bodies. 11 refs., 4 figs.
Discretization on the cosmic scale inspired from the Old Quantum Mechanics
Agnese, A G
1998-01-01
The Old Quantum Mechanics actions discretization rules for periodic motions on the atomic scale (Bohr-Sommerfeld) have been suitably modified in order to account the gravitational field instead of the electrostatic one. The new rules are used to calculate a few mechanical quantities pertinent to the periodic motions of celestial bodies. Several values have been obtained which result in reasonable agreement with the corresponding experimental data. A gravitational dimensionless structure constant has been determined, using the data relative to the solar sistem, which allows to quantitatively account for phenomena on a much wider scale. In particular, some information is acquired about the recently discovered extrasolar planetary systems and about the general empirical law which connects the spin of a celestial body with the square of its mass.
Levy, David H
2011-01-01
When a dissertation gets completed, the normal rule is that it is never read. By anyone. David H. Levy’s dissertation - The Sky in Early Modern English Literature: A Study of Allusions to Celestial Events in Elizabethan and Jacobean Writing, 1572-1620 - is different. It opens a whole new interdisciplinary field, which involves the beautiful relationship between the night sky and the works of the early modern period of English Literature. Although the sky enters into much of literature through the ages, the period involving William Shakespeare and his colleagues is particularly rich. When Shakespeare was about 8 years old, his father probably took him outside his Stratford home into their northward-facing back yard. There, father and son gazed upon the first great new star visible in the past 500 years, shining forth as brightly as Venus, and even visible in daylight. This new star, which we now know as a supernova, completely unhinged old ideas about the cosmos. Com...
Shefer, V. A.; Shefer, O. V.
2016-05-01
Intermediate perturbed orbits, which were proposed earlier by the first author and are calculated based on three position vectors and three measurements of angular coordinates of a small celestial body, are examined. Provided that the reference time interval encompassing the measurements is short, these orbits are close in the accuracy of approximation of actual motion to an orbit with fourth-order tangency. The shorter the reference time interval is, the better is the approximation. The laws of variation of the errors of methods for constructing such intermediate orbits with the length of the reference time interval are formulated. According to these laws, the rate of convergence of the methods to an exact solution in the process of shortening of the reference time interval is, in general, three orders of magnitude higher than that of conventional methods relying on an unperturbed Keplerian orbit. The considered orbits are among the most accurate of their class that is defined by the order of tangency. The obtained theoretical results are verified by numerical experiments on determining the orbit of 99942 Apophis.
Bernardi, G; Brentjens, M A; Ciardi, B; Jelić, V; Koopmans, L V E; Labropoulos, P; Offringa, A; Pandey, V N; Schaye, J; Thomas, R M; Yatawatta, S; Zaroubi, S
2010-01-01
In the coming years a new insight into galaxy formation and the thermal history of the Universe is expected to come from the detection of the highly redshifted cosmological 21 cm line. The cosmological 21 cm line signal is buried under Galactic and extragalactic foregrounds which are likely to be a few orders of magnitude brighter. Strategies and techniques for effective subtraction of these foreground sources require a detailed knowledge of their structure in both intensity and polarization on the relevant angular scales of 1-30 arcmin. We present results from observations conducted with the Westerbork telescope in the 140-160 MHz range with 2 arcmin resolution in two fields located at intermediate Galactic latitude, centred around the bright quasar 3C196 and the North Celestial Pole. They were observed with the purpose of characterizing the foreground properties in sky areas where actual observations of the cosmological 21 cm line could be carried out. The polarization data were analysed through the rotatio...
Energy Technology Data Exchange (ETDEWEB)
Moskalenko, Igor V.; Porter, Troy A.; Digel, Seth W.; Michelson, Peter F.; Ormes, Jonathan F.
2007-12-17
We calculate the {gamma}-ray albedo flux from cosmic-ray (CR) interactions with the solid rock and ice in Main Belt asteroids and Kuiper Belt objects (KBOs) using the Moon as a template. We show that the {gamma}-ray albedo for the Main Belt and Kuiper Belt strongly depends on the small-body mass spectrum of each system and may be detectable by the forthcoming Gamma Ray Large Area Space Telescope (GLAST). The orbits of the Main Belt asteroids and KBOs are distributed near the ecliptic, which passes through the Galactic center and high Galactic latitudes. If detected, the {gamma}-ray emission by the Main Belt and Kuiper Belt has to be taken into account when analyzing weak {gamma}-ray sources close to the ecliptic, especially near the Galactic center and for signals at high Galactic latitudes, such as the extragalactic {gamma}-ray emission. Additionally, it can be used to probe the spectrum of CR nuclei at close-to-interstellar conditions, and the mass spectrum of small bodies in the Main Belt and Kuiper Belt. The asteroid albedo spectrum also exhibits a 511 keV line due to secondary positrons annihilating in the rock. This may be an important and previously unrecognized celestial foreground for the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) observations of the Galactic 511 keV line emission including the direction of the Galactic center.
Taris, F.; Andrei, A.; Roland, J.; Klotz, A.; Vachier, F.; Souchay, J.
2016-03-01
Context. The Gaia astrometric mission of the European Space Agency was launched on December 2013. It will provide a catalog of 500 000 quasars. Some of these targets will be chosen to build an optical reference system that will be linked to the International Celestial Reference Frame (ICRF). The astrometric coordinates of these sources will have roughly the same uncertainty at both optical and radio wavelengths, and it is then mandatory to observe a common set of targets to build the link. In the ICRF, some targets have been chosen because of their pointlikeness. They are quoted as defining sources, and they ensure very good uncertainty about their astrometric coordinates. At optical wavelengths, a comparable uncertainty could be achieved for targets that do not exhibit strong astrophysical phenomena, which is a potential source of photocenter flickering. A signature of these phenomena is a magnitude variation at optical wavelengths. Aims: The goal of this work is to present the time series of 14 targets suitable for the link between the ICRF and the future Gaia Celestial Reference Frame. The observations have been done systematically by robotic telescopes in France and Chile once every two nights since 2011 and in two filters. These time series are analyzed to search for periodic or quasi-periodic phenomena that must be taken into account when computing the uncertainty about the astrometric coordinates. Methods: Two independent methods were used in this work to analyze the time series. We used the CLEAN algorithm to compare the frequency obtained to those given by the Lomb-Scargle method. It avoids misinterpreting the frequency peaks given in the periodograms. Results: For the 14 targets we determine some periods with a confidence level above 90% in each case. Some of the periods found in this work were not previously known. For the others, we did a comparative study of the periods previously studied by others and always confirm their values. All the periods given
The Antikythera mechanism and the mechanical universe
Edmunds, M. G.
2014-10-01
How did our view of the Universe develop? By the mid-eighteenth century, a world view had developed of a system constrained by physical laws. These laws, if not entirely understood, showed regularity and could be handled mathematically to provide both explanation and prediction of celestial phenomena. Most of us have at least some hazy idea of the fundamental shift that came through the work of Copernicus, Kepler, Galileo and Newton. The idea of a 'Mechanical Universe' running rather like a clock tends to be associated with these sixteenth- and seventeenth-century pioneers. It remains a useful - and perhaps comforting - analogy. Yet, recent investigations based around the Antikythera Mechanism, an artefact from ancient Greece, reinforce a view that the 'Mechanical' conception has been around for a much longer time - indeed certainly as far back as the third century BC. The extent of mechanical design expertise existing around 100 BC as witnessed by the Antikythera Mechanism comes as a great surprise to most people. It is certainly a very ingenious device, often referred to as 'The World's First Computer' although it is really a sophisticated mechanical astronomical calculator with its functions pre-determined rather than programmable. In this review, the structure and functions of the Antikythera Mechanism are described. The astronomy, cosmology and technology inherent in the machine fit surprisingly well into the context of its contemporary Classical world. A strong claim will be made for the influence of such mechanisms on the development of astronomical and philosophical views, based on literary reference. There is evidence that the technology persisted until its spectacular and rather sudden re-appearance in Western Europe around 1300 AD. From then on it is not hard to chart a path through the astronomical clocks of the sixteenth century to Kepler's aim (expressed in a 1605 letter) to 'show that the heavenly machine is not a kind of divine, live being, but a
A Gravitational-Tidal Mechanism for the Earth's Polar Oscillations
Akulenko, L. D.; Kumakshev, S. A.; Markov, Yu. G.; Rykhlova, L. V.
2005-10-01
Perturbed, rotational-oscillational motions of the Earth induced by the gravitational torques exerted by the Sun and Moon are studied using a linear mechanical model for a viscoelastic rigid body. A tidal mechanism is identified for the excitation of polar oscillations, i.e., for oscillations of the angular-velocity vector specified in a fixed coordinate frame, attributed to the rotational-progressive motion of the barycenter of the Earth-Moon “binary planet” about the Sun. The main features of the oscillations remain stable and do not change considerably over time intervals significantly exceeding the precessional period of the Earth’s axis. A simple mathematical model containing two frequencies, namely, the Chandler and annual frequencies, is constructed using the methods of celestial mechanics. This model is adequate to the astrometric measurements performed by the International Earth Rotation Service (IERS). The parameters of the model are identified via least-squares fitting and a spectral analysis of the IERS data. Statistically valid interpolations of the data for time intervals covering from several months to 15 20 yr are obtained. High-accuracy forecasting of the polar motions for 0.5 1 yr and reasonably trustworthy forecasting for 1 3 yr demonstrated by observations over the last few years are presented for the first time. The results obtained are of theoretical interest for dynamical astronomy, geodynamics, and celestial mechanics, and are also important for astrometrical, navigational, and geophysical applications.
Celestial dynamics chaoticity and dynamics of celestial systems
Dvorak, Rudolf
2013-01-01
Written by an internationally renowned expert author and researcher, this monograph fills the need for a book conveying the sophisticated tools needed to calculate exo-planet motion and interplanetary space flight. It is unique in considering the critical problems of dynamics and stability, making use of the software Mathematica, including supplements for practical use of the formulae.A must-have for astronomers and applied mathematicians alike.
sources, (4) the physical conditions in the pulsating x-ray source in the Crab Nebula , and (5) miscellaneous related topics. A bibliography of all work performed under the contract is given. (Author)
COCO: Conversion of Celestial Coordinates
Wallace, Patrick
2014-06-01
The COCO program converts star coordinates from one system to another. Both the improved IAU system, post-1976, and the old pre-1976 system are supported. COCO can perform accurate transformations between multiple coordinate systems. COCO's user-interface is spartan but efficient and the program offers control over report resolution. All input is free-format, and defaults are provided where this is meaningful. COCO uses SLALIB (ascl:1403.025) and is distributed as part of the Starlink software collection (ascl:1110.012).
Celestial Fireworks from Dying Stars
2011-04-01
This image of the nebula NGC 3582, which was captured by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile, shows giant loops of gas bearing a striking resemblance to solar prominences. These loops are thought to have been ejected by dying stars, but new stars are also being born within this stellar nursery. These energetic youngsters emit intense ultraviolet radiation that makes the gas in the nebula glow, producing the fiery display shown here. NGC 3582 is part of a large star-forming region in the Milky Way, called RCW 57. It lies close to the central plane of the Milky Way in the southern constellation of Carina (The Keel of Jason's ship, the Argo). John Herschel first saw this complex region of glowing gas and dark dust clouds in 1834, during his stay in South Africa. Some of the stars forming in regions like NGC 3582 are much heavier than the Sun. These monster stars emit energy at prodigious rates and have very short lives that end in explosions as supernovae. The material ejected from these dramatic events creates bubbles in the surrounding gas and dust. This is the probable cause of the loops visible in this picture. This image was taken through multiple filters. From the Wide Field Imager, data taken through a red filter are shown in green and red, and data taken through a filter that isolates the red glow characteristic of hydrogen are also shown in red. Additional infrared data from the Digitized Sky Survey are shown in blue. The image was processed by ESO using the observational data identified by Joe DePasquale, from the United States [1], who participated in ESO's Hidden Treasures 2010 astrophotography competition [2]. The competition was organised by ESO in October-November 2010, for everyone who enjoys making beautiful images of the night sky using astronomical data obtained using professional telescopes. Notes [1] Joe searched through ESO's archive and identified datasets that he used to compose his image of NGC 3582, which was the tenth highest ranked entry in the competition, out of almost 100 entries. His original work can be seen here. [2] ESO's Hidden Treasures 2010 competition gave amateur astronomers the opportunity to search through ESO's vast archives of astronomical data, hoping to find a well-hidden gem that needed polishing by the entrants. To find out more about Hidden Treasures, visit http://www.eso.org/public/outreach/hiddentreasures/. More information ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory and VISTA, the world's largest survey telescope. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become "the world's biggest eye on the sky".
Institute of Scientific and Technical Information of China (English)
张健; 张培瑜
2012-01-01
The Bamboo Annals is the history book unearthed by West Jin Dynasty in the tomb of Wei King of the third century BC, It recorded a lot of chronology and historical facts of the Xia Shang Zhou period, but the Bamboo Annals gradually lost during 12 or 13 century. Today there are two sorts of the Bamboo Annals we can read, one is the Ancient Text of the Bamboo Annals compiled by the modern scholars, the other is an entire book called the Modern Text of the Bamboo Annals. The latter was probably found by Yuan or Ming Dynasty. The Modern Text of the Bamboo Annals is different from the Ancient Text on the writing and contents, more of celestial phenomena are recorded to the Modern Text of the Bamboo Annals than to the Ancient Text. It is discussed in this paper that the celestial phenomena and chronology are recorded in the Bamboo Annals, the results show that these celestial phenomena of the Modern Text of the Bamboo Annals are not original records unearthed by West Jin Dynasty in the tomb of Wei King of the third century BC, but were supplemented by the scholars of Song and Yuan Dynasties.%对《竹书纪年》记载的天象和纪年进行了初步的分析研究,结果表明,今本《竹书纪年》中新增的天象如日食等,并非汲冢出土佚书的原有内容,而为宋元以后学者所加.
Horváth, Gábor; Takács, Péter; Kretzer, Balázs; Szilasi, Szilvia; Száz, Dénes; Farkas, Alexandra; Barta, András
2017-02-01
If a human looks at the clear blue sky from which light with high enough degree of polarization d originates, an 8-shaped bowtie-like figure, the yellow Haidinger's brush can be perceived, the long axis of which points towards the sun. A band of high d arcs across the sky at 90° from the sun. A person can pick two points on that band, observe the yellow brushes and triangulate the position of the sun based on the orientation of the two observed brushes. This method has been suggested to have been used on the open sea by Viking navigators to determine the position of the invisible sun occluded by cloud or fog. Furthermore, Haidinger's brushes can also be used to locate the sun when it is below the horizon or occluded by objects on the horizon. To determine the position of the sun using the celestial polarization pattern, the d of the portion of the sky used must be greater than the viewer's degree of polarization threshold d* for perception of Haidinger's brushes. We studied under which sky conditions the prerequisite d > d* is satisfied. Using full-sky imaging polarimetry, we measured the d-pattern of skylight in the blue (450 nm) spectral range for 1296 different meteorological conditions with different solar elevation angles θ and per cent cloud cover ρ. From the measured d-patterns of a given sky we determined the proportion P of the sky for which d > d*. We obtained that P is the largest at low solar elevations θ ≈ 0° and under totally or nearly clear skies with cloud coverage ρ = 0%, when the sun's position is already easily determined. If the sun is below the horizon (-5° ≤ θ sky conditions. Consequently, the sky-polarimetric Viking navigation based on Haidinger's brushes is most useful after sunset and prior to sunrise, when the sun is not visible and large sky regions are bright, clear and polarized enough for perception of Haidinger's brushes.
Directory of Open Access Journals (Sweden)
Paulo Sergio Bretones
2011-01-01
Full Text Available Este é um estudo sobre a elaboração do conceito de movimento diário da esfera celeste por um grupo de professores de Ciências e Geografia de 5ª a 8ª séries, participantes de um curso de Astronomia. Os resultados baseiam-se, sobretudo, na análise de suas respostas às perguntas das avaliações e em registros de aulas do curso. Discutem-se: a relação entre as respostas dos participantes, seus relatos sobre suas observações, e o desenvolvimento de conteúdos referentes ao movimento de constelações. Apresentam-se as elaborações de sequências da evolução conceitual do grupo e sua relação com a prática e a teoria trabalhadas no curso. Tais elaborações revelam os princípios relacionados à observação do céu: relação da altura do polo celeste com a latitude geográfica, obliquidade, continuidade do movimento, circularidade, tridimensionalidade e ciclicidade. O estudo sugere que esses princípios, usados como guias heurísticos, seriam úteis para o ensino da observação do céu.This work presents a study about the concept formation of the daily motion of the celestial sphere by a group of middle school teachers participants of an Astronomy course. The results are based on the analyses of the answers of these teachers for the questions made in the check tests and the records from the classes of the course. It is studied the relation between the answers, the accounts of the sky observations by the participants and the development of the contents about the daily motion of the celestial sphere. The elaborations of sequences of the verified conceptual evolution by the group and its relation with the theory develop in the course are presented. After a closer look at the elaborations of the participants, some principles were revealed: the elevation of the celestial pole to geographic latitude, obliquity, continuity of motion, circularity, tri-dimensionality and cyclicity. The study suggests that these principles shoud be used
Institute of Scientific and Technical Information of China (English)
张继福; 李鑫; 杨海峰
2012-01-01
连续数值属性离散化是天文光谱数据预处理中的主要研究内容之一.针对天文光谱特征线,提出了一种基于改进模糊C均值聚类的天文光谱特征线软离散化算法.该算法首先利用样本的密度值选取特征线的候选初始模糊聚类中心,有效地克服了对噪声数据敏感的缺陷；其次采用决策表中的相容性作为评判标准,动态的调节聚类参数,以达到优化的光谱特征线离散化效果；最后采用晚型星、类星体、高红移类星体SDSS天文光谱特征线数据集.实验验证了该算法具有较高的识别率,为天文光谱特征线数据预处理提供了一种新途径.%Discretization of continuous numerical attribute is one of the important research works in the preprocessing of celestial spectrum data. For characteristic line of celestial spectrum, a soft discretization algorithm is presented by using improved fuzzy C-means clustering. Firstly, candidate fuzzy clustering centers of characteristic line are chosen by using density values of sample data, so that its anti-noise ability is improved. Secondly, parameters in the fuzzy clustering are dynamically adjusted by taking compatibility of decision table as criteria, so that optimal discretization effect of the characteristic line is achieved. In the end, experimental results effectively validate that the algorithm has higher correct recognition rate of the algorithm by using three SDSS celestial spectrum data sets of high-redshift quasars, late-type star and quasars.
Institute of Scientific and Technical Information of China (English)
阿里·捷木思; 房建成
2005-01-01
This paper presents an in-flight alignment technique for a strapdown inertial navigation system (SINS) and employs a star pattern recognition procedure for identifying stars sensed by a CCD electrooptical star sensor. Collinearity equations are used to estimate sensor frame star coordinates and the conventional least square differ-ential correction method is used to estimate the unknown orientation angles. A comparison of this attitude with the attitude estimated by the SINS provides axis misalignment angles. Simulations using a Kalman filter are carried out for an SINS and the system employs a local level navigation frame. The space stabilized SINS is discussed in conjunction with the celestial aiding. Based on the observation of the Kalman filter, the estimating and compensating gyro errors, as well as the position and velocity errors caused by the SINS misalignments are calibrated by celestial attitute information.%提出了一种基于CCD星敏感器的捷联惯性导航系统的空中对准方法.应用双线性方程求解被观测星在星敏感器坐标系中的坐标值及传统最小二乘微分校正法求解捷联惯性导航的姿态,该姿态值与捷联惯性导航解算姿态的差值就是惯性导航系统的失准角.作为Kalman滤波器的观测量,计算机仿真结果表明,天文姿态信息有效地校正了陀螺漂移和初始失准角引起的位置和速度误差.
About mechanisms of tetonic activity of the satellites
Barkin, Yu. V.
2003-04-01
ABOUT MECHANISMS OF TECTONIC ACTIVITY OF THE SATELLITES Yu.V. Barkin Sternberg Astronomical Institute, Moscow, Russia, barkin@sai.msu.ru Due to attraction of the central planet and others external bodies satellite is subjected by tidal and non-tidal deformations. Elastic energy is changed in dependence from mutual position and motion of celestial bodies and as result the tensional state of satellite and its tectonic (endogenous) activity also is changed. Satellites of the planets have the definite shell’s structure and due to own rotation these shells are characterized by different oblatenesses. Gravitational interaction of the satellite and its mother planet generates big additional mechanical forces (and moments) between the neighboring non-spherical shells of the satellite (mantle, core and crust). These forces and moments are cyclic functions of time, which are changed in the different time-scales. They generate corresponding cyclic perturbations of the tensional state of the shells, their deformations, small relative transnational displacements and slow rotation of the shells and others. In geological period of time it leads to a fundamental tectonic reconstruction of the body. Definite contribution to discussed phenomena are caused by classical tidal mechanism. of planet-satellite interaction. But in this report we discuss in first the new mechanisms of endogenous activity of celestial bodies. They are connected with differential gravitational attraction of non-spherical satellite shells by the external celestial bodies which leads: 1) to small relative rotation (nutations) of the shells; 2) to small relative translational motions of the shells (displacements of their center of mass); 3) to relative displacements and rotations of the shells due to eccentricity of their center of mass positions; 4) to viscous elastic deformations of the shells and oth. (Barkin, 2001). For higher evaluations of the power of satellite endogenous activities were obtained
A SOLAR SYSTEM EPHEMERIS FOR 1950 TO 2000.
SOLAR SYSTEM, CELESTIAL MECHANICS, COMPUTER PROGRAMMING, CELESTIAL MECHANICS, VELOCITY, PLANETS , MOON, MERCURY ( PLANET ), VENUS( PLANET ), MARS( PLANET ), JUPITER( PLANET ), SATURN( PLANET ), URANUS( PLANET ), PLUTO( PLANET ).
大行星、月球和小天体环绕型探测器的轨道问题%Orbits of Orbiting Probes Around Planets, Moon and Small Celestial Bodies
Institute of Scientific and Technical Information of China (English)
刘林; 汤靖师
2012-01-01
The features of orbiting probes around celestial major bodies are discussed. The major bodies are selected with different physical characteristics, depending on their masses which determine the influence sphere and their density distributions and shapes which determine the gravity field. The possible motions and different characteristics of the orbiting probes around respective celestial bodies are discussed in detail, together with the discussion on two forms of formation flying. Lunar probes, whose energy dissipation is not a concern as for planetary probes, still have a problem on orbit life. Since the lunar mass distribution is not uniform, the orbit life is closely related to the orbit inclination. For Mars probes, although similar phenomenon exists, the rela- tion with orbit inclination is different. These major features of orbit variation can be used to serve the orbit design and selection in deep space exploration.%针对环绕型探测器的轨道,以具有不同物理特征的大天体（金星、火星和月球等）为例,根据它们的质量大小（决定其引力作用范围的大小）、密度分布和形状特征（决定其非球形引力场的特征）,具体阐述了它们各自环绕型探测器轨道的可能形式和不同的变化特征,另外介绍了小天体探测时的两种伴飞形式。关于环绕型探测器的轨道特征,如月球无大气,对其低轨探测器而言没有能量耗散影响,却同样有轨道寿命问题,而且由于其质量分布不均匀,这种现象还与轨道倾角有密切关系;而对火星的环绕型探测器而言,尽管有类似现象,但与轨道倾角的关系却大不相同。这些重要的轨道变化特征,可为深空探测中目标轨道的选择和设计提供依据。
Institute of Scientific and Technical Information of China (English)
王融; 熊智; 刘建业; 钟丽娜
2013-01-01
The traditional inertial/celestial integrated navigation system (INS/CNS) is inapplicable for hypersonic vehicle, because it can’t work under the body coordinate accordance and single-star visible condition. In this paper, a tightly-coupled INS/GPS/CNS integrated navigation scheme for hypersonic vehicle is investigated. The new INS/CNS integrated model is built based on transformational relation between starlight elevation/azimuth and INS errors. The new model can stabilize the measurement noise characteristic and work under single-star visible condition, thus can improve the continuity and accuracy of INS/CNS integration. The simulation of hypersonic vehicle navigation indicates that, the system assisted by celestial angle observation shows 60%-70% improvement in attitude accuracy than the unassisted system.%常规惯性/天文组合导航方法难以直接应用于高超声速飞行器机载环境下以载体系为基准进行星光测量的情况，且在可见星只有一颗时无法连续组合。为此，构建了高超声速飞行器惯性/卫星/天文紧组合导航系统方案，通过分析载体系下星光仰角、方位角与惯导误差之间的转换关系，建立了载体系下惯性/天文角度组合模型。理论分析表明，该系统在只有一颗导航星时仍能辅助惯导工作，且可使观测噪声特性保持稳定，从而提高了天文对惯导辅助的连续性和组合滤波估计精度。仿真结果表明，在高超声速飞行器导航系统采用天文角度辅助后，姿态误差较无天文辅助情况的降低60%~70%。
Gravitational mechanism of active life of the Earth, planets and satellites
Barkin, Yury
2010-05-01
From positions of geodynamic model of the forced gravitational swing, wobble and displacements of shells of a planet are studied and fundamental problems of geodynamics, geology, geophysics, planetary sciences are solved etc.: 1) The mechanism of cyclic variations of activity of natural processes in various time scales. 2) The power of endogenous activity of planetary natural processes on planets and satellites. 3) The phenomenon of polar inversion of natural processes on planets and satellites. 4) Spasmodic and catastrophic changes of activity of natural processes. 5) The phenomenon of twisting of hemispheres (latitude zones or belts) of celestial bodies. 6) Formation of the pear-shaped form of celestial bodies and the mechanism of its change. 7) The ordered planetary structures of geological formations. 8) The phenomena of bipolarity of celestial bodies and antipodality of geology formations. Mechanism. The fundamental feature of a structure of celestial bodies is their shell structure. The most investigated is the internal structure of the Earth. For the Moon and wide set of other bodies of solar system models of an internal structure have been constructed on the basis of the data of observations obtained at studying of their gravitational fields as a result of realization of the appropriate space missions. The basic components for the majority of celestial bodies are the core, the mantle and the crust. To other shells we concern atmospheres (for example, at Venus, Mars, the Titan etc.) and oceanic shells (the Titan, the Earth, Enceladus etc.). Shells are the complex (composite) formations. Planets and satellites are not spherical celestial bodies. The centers of mass of shells of the given planet (or the satellite) and their appropriate principal axes of inertia do not coincide. Accordingly, all their shells are characterized by the certain dynamic oblatenesses. Differences of dynamical oblatenesses results in various forced influences of external celestial
Taketa, I.; Matsumoto, I.
2014-12-01
In general, elementary school teacher relatively poor at the science field about "earth and universe". There is the science unit "the Moon and the Sun" in the sixth grader in elementary school in Japan. In this study, we developed the effective teaching material that is both student is easy understanding and teacher is easy treating. The teaching material that we developed is the Movement of the Moon and the Sun using about 30-cm turntable and a USB Camera. As for the previous teaching materials, every student was checking (see) the moon and the sun spatial relationship, and the shape of the moon to each. The developed teaching material have the advantage that all student in the class can check the same phenomenon on a Video screen, by using a USB Camera. And we carried the questionnaire survey to student of attached elementary school of Shimane University. The result checked that such teaching materials were useful to a student's understanding of the movement of the celestial sphere.
Warming: mechanism and latitude dependence
Barkin, Yury
2010-05-01
Introduction. In the work it is shown, that in present warming of climate of the Earth and in style of its display a fundamental role the mechanism of the forced swing and relative oscillations of eccentric core of the Earth and its mantle plays. Relative displacements of the centers of mass of the core and the mantle are dictated by the features of orbital motions of bodies of solar system and nonineriality of the Earth reference frame (or ot the mantle) at the motion of the Earth with respect to a baricenter of solar system and at rotation of the planet. As a result in relative translational displacements of the core and the mantle the frequencies characteristic for orbital motion of all bodies of solar system, and also their combination are shown. Methods of a space geodesy, gravimetry, geophysics, etc. unequivocally and clearly confirm phenomenon of drift of the center of mass of the Earth in define northern direction. This drift is characterized by the significant velocity in about 5 mm/yr. The unique opportunity of its explanation consists in the natural assumption of existence of the unidirectional relative displacement (drift) the center of mass of the core and the center of mass of the mantle of the Earth. And this displacement (at superfluous mass of the core in 16.7 % from the mass of full the Earth) is characterized still more significant velocity in 2.6 cm/yr and occurs on our geodynamic studies in a direction to Taimyr peninsula. The dynamic explanation to century drift for today does not exist. It is possible to note, however, that data of observations of last years, indirectly testifying that similar drifts of the centers of mass in present epoch occur on other bodies of Solar system have been obtain: the Sun, Mars, the Titan, Enceladus, the Neptune, etc. We connect with mentioned phenomena the observed secular variations of natural processes on this celestial bodies. I.e. it is possible to assume, that observable eccentric positions of the centers
Celestial-themed Cartoons Captivate Children
Cappelli, V.; di Benedetto, C.
2010-12-01
Attivamente: Big discoveries with Galileo and Phineas & Ferb, an educational entertainment project for children, was a collaboration between Disney Television Italy and the Education and Public Outreach office of the INAF Astronomical Observatory of Padua, Italy. The project started during the International Year of Astronomy 2009 and came to an end in June 2010. It consisted of a cartoon series, several articles in a Disney magazine and an educational kit focused on Galileo Galilei and the Moon. The kit, called the First Astronomical Kit, was distributed to 30 000 children in Italy, and included a board game about the Moon, an observation diary and a lunar fact card. The aim of the kit was to give children some basic astronomical knowledge and to demonstrate the essential role that observation plays in understanding the heavens. This article discusses how a research institute and a major entertainment company -- each with very different working practices -- were able to work together to form a successful partnership.
Theories of figures of celestial bodies
Jardetzky, Wenceslas S
2005-01-01
Everything in the universe rotates: the meteors, the asteroids, the planets and their satellites, the sun, the stars, the clusters and nebulae, even the galaxies themselves. The problem of the shape of a rotating body is therefore universal in astronomy. Its treatment in this book, which deals with the figures of equilibrium and distortions of rotating bodies, is full and rigorous.Suitable for upper-level undergraduates and graduate students, this text was written by a renowned researcher and educator who taught at Columbia University and served for many years as a research associate at the La
Celestial moderation of tropical seabird behavior.
Pinet, Patrick; Jaeger, Audrey; Cordier, Emmanuel; Potin, Gaël; Le Corre, Matthieu
2011-01-01
Most animals, including birds, have cyclic life histories and numerous studies generally conducted on captive animals have shown that photoperiod is the main factor influencing this periodicity. Moon cycles can also affect periodic behavior of birds. Few studies have investigated the influence of these environmental cues in natural settings, and particularly in tropical areas where the change in photoperiod is slight and some bird species keep cyclic behaviors. Using miniaturized light sensors, we simultaneously investigated under natural conditions the influence of photoperiod and moon phases on the migration dates and at-sea activity of a tropical seabird species, the Barau's petrel, throughout its annual cycle. Firstly, we found that birds consistently started their pre- and post-breeding migrations at precise dates corresponding in both cases to a day-duration of 12.5 hours, suggesting a strong influence of the photoperiod in the regulation of migration behavior. We also found that mean population arrival dates to the colony changed from year to year and they were influenced by moon phases. Returns at their colonies occurred around the last full moon of the austral winter, suggesting that moon cycle is used by birds to synchronize their arrival. Secondly, variations of day-time activity were sinusoidal and correlated to seasonal changes of daylength. We thus hypothesize that the photoperiod could directly affect the behavior of the birds at sea. Night-time at-sea activity exhibited a clear cycle of 29.2 days, suggesting that nocturnal foraging was highly regulated by moon phase, particularly during the non-breeding season. To our knowledge, this is the first study to document a mixed regulation of the behavior of a wild bird by photoperiod and moon phases throughout its annual cycle.
Celestial moderation of tropical seabird behavior.
Directory of Open Access Journals (Sweden)
Patrick Pinet
Full Text Available Most animals, including birds, have cyclic life histories and numerous studies generally conducted on captive animals have shown that photoperiod is the main factor influencing this periodicity. Moon cycles can also affect periodic behavior of birds. Few studies have investigated the influence of these environmental cues in natural settings, and particularly in tropical areas where the change in photoperiod is slight and some bird species keep cyclic behaviors. Using miniaturized light sensors, we simultaneously investigated under natural conditions the influence of photoperiod and moon phases on the migration dates and at-sea activity of a tropical seabird species, the Barau's petrel, throughout its annual cycle. Firstly, we found that birds consistently started their pre- and post-breeding migrations at precise dates corresponding in both cases to a day-duration of 12.5 hours, suggesting a strong influence of the photoperiod in the regulation of migration behavior. We also found that mean population arrival dates to the colony changed from year to year and they were influenced by moon phases. Returns at their colonies occurred around the last full moon of the austral winter, suggesting that moon cycle is used by birds to synchronize their arrival. Secondly, variations of day-time activity were sinusoidal and correlated to seasonal changes of daylength. We thus hypothesize that the photoperiod could directly affect the behavior of the birds at sea. Night-time at-sea activity exhibited a clear cycle of 29.2 days, suggesting that nocturnal foraging was highly regulated by moon phase, particularly during the non-breeding season. To our knowledge, this is the first study to document a mixed regulation of the behavior of a wild bird by photoperiod and moon phases throughout its annual cycle.
Asteroids - the modern challenge of celestial dynamics
Dikova, Smiliana
2002-11-01
Among the most powerful statements in Science are those that mark absolute limits to knowledge. For example, Relativity and Quantum Theory touched the limits of speed and accuracy. Deterministic Chaos - the new scientific paradigma of our days, also falls in this class theories. Chaos means complexity in space and unpredictability in time. It shows the limit of our basic counting system and leads to a limited predictability of the long time dynamical evolution. Perhaps for that reason, in 1986 Sir James Lighthill remarked for all physicists: "We collectively wish to apologize for having misled the general educated public by spreading ideas about the determinism of systems satisfying Newton's laws of motion that, after 1960, were proved incorrect." Our main thesis is that Asteroid Dynamics is the arena where the drama Chaos versus predictability is initiated and developed. The aim of the present research is to show the way in which Deterministic Chaos restricts the long term dynamical predictability of asteroid motions.
Celestial Beauty Leads The Hainan Airlines
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
Based on the corporate culture of"intemally cultivating the spirit with the essence of the traditional Chinese culture,and externally combining the advanced western management and technology",Hainan Airlines Company Limited (hereinafter called HNA) has turned from a new soaring airlines to the fourth biggest airlines in China.……
Celestial Beauty Leads The Hainan Airlines
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
@@ Based on the corporate culture of"intemally cultivating the spirit with the essence of the traditional Chinese culture,and externally combining the advanced western management and technology",Hainan Airlines Company Limited (hereinafter called HNA) has turned from a new soaring airlines to the fourth biggest airlines in China.
van Deventer, M. Oskar
2009-01-01
The basis of a good mechanical puzzle is often a puzzling mechanism. This article will introduce some new puzzling mechanisms, like two knots that engage like gears, a chain whose links can be interchanged, and flat gears that do not come apart. It illustrates how puzzling mechanisms can be transformed into real mechanical puzzles, e.g., by…
Institute of Scientific and Technical Information of China (English)
司建敏; 罗阿理; 吴福朝; 吴毅红
2015-01-01
There are many valuable rare and unusual objects in spectra dataset of Sloan Digital Sky Survey (SDSS)Data Release eight (DR8),such as special white dwarfs (DZ,DQ,DC),carbon stars,white dwarf main-sequence binaries (WDMS),cata-clysmic variable (CV)stars and so on,so it is extremely significant to search for rare and unusual celestial objects from massive spectra dataset.A novel algorithm based on Kernel dense estimation and K-nearest neighborhoods (KNN)has been presented, and applied to search for rare and unusual celestial objects from 546 383 stellar spectra of SDSS DR8.Their densities are esti-mated using Gaussian kernel density estimation,the top 5 000 spectra in descend order by their densities are selected as rare ob-jects,and the top 300 000 spectra in ascend order by their densities are selected as normal objects.Then,KNN were used to classify the rest objects,and simultaneously K nearest neighbors of the 5 000 rare spectra are also selected as rare objects.As a result,there are totally 21 193 spectra selected as initial rare spectra,which include error spectra caused by deletion,redden, bad calibration,spectra consisting of different physically irrelevant components,planetary nebulas,QSOs,special white dwarfs (DZ,DQ,DC),carbon stars,white dwarf main-sequence binaries (WDMS),cataclysmic variable (CV)stars and so on.By cross identification with SIMBAD,NED,ADS and major literature,it is found that three DZ white dwarfs,one WDMS,two CVs with company of G-type star,three CVs candidates,six DC white dwarfs,one DC white dwarf candidate and one BL Lacer-tae (BL lac)candidate are our new findings.We also have found one special DA white dwarf with emission lines of CaⅡ triple and MgⅠ,and one unknown object whose spectrum looks like a late M star with emission lines and its image looks like a galaxy or nebula.%SDSS DR8海量光谱中包含许多有研究价值的稀有天体，如特殊白矮星（DZ，DQ，DC）、碳星、白矮主序双星、激变变星等
Spencer, A J M
2004-01-01
The mechanics of fluids and the mechanics of solids represent the two major areas of physics and applied mathematics that meet in continuum mechanics, a field that forms the foundation of civil and mechanical engineering. This unified approach to the teaching of fluid and solid mechanics focuses on the general mechanical principles that apply to all materials. Students who have familiarized themselves with the basic principles can go on to specialize in any of the different branches of continuum mechanics. This text opens with introductory chapters on matrix algebra, vectors and Cartesian ten
Institute of Scientific and Technical Information of China (English)
娄圣金; 张继福; 杨海峰
2013-01-01
Outlier mining is one of the effective methods to find the abnormal celestial spectrum data,and is also one of effective ways to discover the special and unknown celestial bodies.In the present paper,an abnormal characteristic line mining method of celestial spectrum is presented based on the attribute weight and wk-distance by using the idea of information entropy.Based on it,an abnormal characteristic line mining system of celestial spectrum was designed and implemented.Firstly,attribute weight of characteristic line was determined by using the idea of information entropy,so that important degree was effectively reflected for each characteristic line.Secondly,massive characteristic line data set of celestial spectrum was reduced by utilizing pruning technique based on neighborhood radius,so that candidate set of abnormal characteristic line was obtained by deleting data objects in which there may not be abnormal characteristic lines.Thirdly,wk-distance sum was computed according to the deviation between the data objects in the candidate set,and the objects whose wk-distance sum value ranks the first top n were regarded as abnormal characteristic line data objects.In the end,the experimental and the system's running results validated the effectiveness and feasibility of the method by using the SDSS star spectral data set.%采用信息熵思想,给出一种基于属性权值和wk-距离的异常天体光谱特征线挖掘方法,并开发了天体光谱异常特征线挖掘系统.首先采用信息熵思想计算天体光谱特征线属性权值,从而有效地刻画每条特征线的重要程度；其次采用邻域半径的剪枝技术,对海量天体光谱特征线数据集约简,删除不可能成为异常的数据对象,形成一个候选异常数据集；然后根据离候选异常数据中对象之间的偏差,计算wk-距离和,并选取wkk-距离和较大的前TOP-NN个数据对象作为天文光谱异常特征线数据；最后采用SDSS恒星光谱特
Pulmonary mechanics during mechanical ventilation.
Henderson, William R; Sheel, A William
2012-03-15
The use of mechanical ventilation has become widespread in the management of hypoxic respiratory failure. Investigations of pulmonary mechanics in this clinical scenario have demonstrated that there are significant differences in compliance, resistance and gas flow when compared with normal subjects. This paper will review the mechanisms by which pulmonary mechanics are assessed in mechanically ventilated patients and will review how the data can be used for investigative research purposes as well as to inform rational ventilator management.
Risitano, Antonino
2011-01-01
METHODOLOGICAL STATEMENT OF ENGINEERING DESIGNApproaches to product design and developmentMechanical design and environmental requirementsPROPERTIES OF ENGINEERING MATERIALSMaterials for mechanical designCharacterization of metalsStress conditionsFatigue of materialsOptimum material selection in mechanical designDESIGN OF MECHANICAL COMPONENTS AND SYSTEMSFailure theoriesHertz theoryLubrificationShafts and bearingsSplines and keysSpringsFlexible machine elementsSpur gearsPress and shrink fitsPressure tubesCouplingsClutchesBrakes
Barham, Jerry N.
Mechanical kinesiology is defined as a study of the mechanical factors affecting human movement, i.e., applying the physical laws of mechanics to the study of human motor behavior. This textbook on the subject is divided into thirty lessons. Each lesson is organized into three parts: a part on the text proper; a part entitled "study…
Caltagirone, Jean-Paul
2014-01-01
This book presents the fundamental principles of mechanics to re-establish the equations of Discrete Mechanics. It introduces physics and thermodynamics associated to the physical modeling. The development and the complementarity of sciences lead to review today the old concepts that were the basis for the development of continuum mechanics. The differential geometry is used to review the conservation laws of mechanics. For instance, this formalism requires a different location of vector and scalar quantities in space. The equations of Discrete Mechanics form a system of equations where the H
Stellar performance: mechanisms underlying Milky Way orientation in dung beetles.
Foster, James J; El Jundi, Basil; Smolka, Jochen; Khaldy, Lana; Nilsson, Dan-Eric; Byrne, Marcus J; Dacke, Marie
2017-04-05
Nocturnal dung beetles (Scarabaeus satyrus) are currently the only animals that have been demonstrated to use the Milky Way for reliable orientation. In this study, we tested the capacity of S. satyrus to orient under a range of artificial celestial cues, and compared the properties of these cues with images of the Milky Way simulated for a beetle's visual system. We find that the mechanism that permits accurate stellar orientation under the Milky Way is based on an intensity comparison between different regions of the Milky Way. We determined the beetles' contrast sensitivity for this task in behavioural experiments in the laboratory, and found that the resulting threshold of 13% is sufficient to detect the contrast between the southern and northern arms of the Milky Way under natural conditions. This mechanism should be effective under extremely dim conditions and on nights when the Milky Way forms a near symmetrical band that crosses the zenith. These findings are discussed in the context of studies of stellar orientation in migratory birds and itinerant seals.This article is part of the themed issue 'Vision in dim light'.
Bolton, W C
2013-01-01
This book gives comprehensive coverage of mechanical science for HNC/HND students taking mechanical engineering courses, including all topics likely to be covered in both years of such courses, as well as for first year undergraduate courses in mechanical engineering. It features 500 problems with answers and 200 worked examples. The third edition includes a new section on power transmission and an appendix on mathematics to help students with the basic notation of calculus and solution of differential equations.
Muniz Oliva, Waldyr
2002-01-01
Geometric Mechanics here means mechanics on a pseudo-riemannian manifold and the main goal is the study of some mechanical models and concepts, with emphasis on the intrinsic and geometric aspects arising in classical problems. The first seven chapters are written in the spirit of Newtonian Mechanics while the last two ones as well as two of the four appendices describe the foundations and some aspects of Special and General Relativity. All the material has a coordinate free presentation but, for the sake of motivation, many examples and exercises are included in order to exhibit the desirable flavor of physical applications.
Decoding the ancient Greek astronomical calculator known as the Antikythera Mechanism.
Freeth, T; Bitsakis, Y; Moussas, X; Seiradakis, J H; Tselikas, A; Mangou, H; Zafeiropoulou, M; Hadland, R; Bate, D; Ramsey, A; Allen, M; Crawley, A; Hockley, P; Malzbender, T; Gelb, D; Ambrisco, W; Edmunds, M G
2006-11-30
The Antikythera Mechanism is a unique Greek geared device, constructed around the end of the second century bc. It is known that it calculated and displayed celestial information, particularly cycles such as the phases of the moon and a luni-solar calendar. Calendars were important to ancient societies for timing agricultural activity and fixing religious festivals. Eclipses and planetary motions were often interpreted as omens, while the calm regularity of the astronomical cycles must have been philosophically attractive in an uncertain and violent world. Named after its place of discovery in 1901 in a Roman shipwreck, the Antikythera Mechanism is technically more complex than any known device for at least a millennium afterwards. Its specific functions have remained controversial because its gears and the inscriptions upon its faces are only fragmentary. Here we report surface imaging and high-resolution X-ray tomography of the surviving fragments, enabling us to reconstruct the gear function and double the number of deciphered inscriptions. The mechanism predicted lunar and solar eclipses on the basis of Babylonian arithmetic-progression cycles. The inscriptions support suggestions of mechanical display of planetary positions, now lost. In the second century bc, Hipparchos developed a theory to explain the irregularities of the Moon's motion across the sky caused by its elliptic orbit. We find a mechanical realization of this theory in the gearing of the mechanism, revealing an unexpected degree of technical sophistication for the period.
Şengül, Caner
2016-01-01
College Mechanics QueBank has been designed to be different, enthusiastic, interesting and helpful to you. Therefore, it is not just a test bank about mechanics but also it is like a compass in order to find your way in mechanics Each chapter in this book is put in an order to follow a hierarchy of the mechanics topics; from vectors to simple harmonic motion. Throughout the book there are many multiple choice and long answer questions for you to solve. They have been created for YGS, LYS, SAT, IB or other standardized exams in the world because mechanics has no boundaries and so Physics has no country. Learn the main principle of each chapter and explore the daily life applications. Then you can start to solve the questions by planning a problem solving method carefully. Finally, enjoy solving the questions and discover the meachanics of the universe once more.
Wilson, Theodore A
2016-01-01
This book thoroughly covers each subfield of respiratory mechanics: pulmonary mechanics, the respiratory pump, and flow. It presents the current understanding of the field and serves as a guide to the scientific literature from the golden age of respiratory mechanics, 1960 - 2010. Specific topics covered include the contributions of surface tension and tissue forces to lung recoil, the gravitational deformation of the lung, and the interdependence forces that act on pulmonary airways and blood vessels. The geometry and kinematics of the ribs is also covered in detail, as well as the respiratory action of the external and internal intercostal muscles, the mechanics of the diaphragm, and the quantitative compartmental models of the chest wall is also described. Additionally, flow in the airways is covered thoroughly, including the wave-speed and viscous expiratory flow-limiting mechanisms; convection, diffusion and the stationary front; and the distribution of ventilation. This is an ideal book for respiratory ...
Zehnder, Alan T
2012-01-01
Fracture mechanics is a vast and growing field. This book develops the basic elements needed for both fracture research and engineering practice. The emphasis is on continuum mechanics models for energy flows and crack-tip stress- and deformation fields in elastic and elastic-plastic materials. In addition to a brief discussion of computational fracture methods, the text includes practical sections on fracture criteria, fracture toughness testing, and methods for measuring stress intensity factors and energy release rates. Class-tested at Cornell, this book is designed for students, researchers and practitioners interested in understanding and contributing to a diverse and vital field of knowledge. Alan Zehnder joined the faculty at Cornell University in 1988. Since then he has served in a number of leadership roles including Chair of the Department of Theoretical and Applied Mechanics, and Director of the Sibley School of Mechanical and Aerospace Engineering. He teaches applied mechanics and his research t...
Rae, Alastair I M
2016-01-01
A Thorough Update of One of the Most Highly Regarded Textbooks on Quantum Mechanics Continuing to offer an exceptionally clear, up-to-date treatment of the subject, Quantum Mechanics, Sixth Edition explains the concepts of quantum mechanics for undergraduate students in physics and related disciplines and provides the foundation necessary for other specialized courses. This sixth edition builds on its highly praised predecessors to make the text even more accessible to a wider audience. It is now divided into five parts that separately cover broad topics suitable for any general course on quantum mechanics. New to the Sixth Edition * Three chapters that review prerequisite physics and mathematics, laying out the notation, formalism, and physical basis necessary for the rest of the book * Short descriptions of numerous applications relevant to the physics discussed, giving students a brief look at what quantum mechanics has made possible industrially and scientifically * Additional end-of-chapter problems with...
DEFF Research Database (Denmark)
Restrepo-Giraldo, John Dairo
2006-01-01
Most products and machines involve some kind of controlled movement. From window casements to DVD players, from harbor cranes to the shears to prune your garden, all these machines require mechanisms to move. This course intends to provide the analytical and conceptual tools to design such mechan......Most products and machines involve some kind of controlled movement. From window casements to DVD players, from harbor cranes to the shears to prune your garden, all these machines require mechanisms to move. This course intends to provide the analytical and conceptual tools to design...... such mechanisms. This is a horizontal subject, which means you will be asked to make use of your knowledge in different disciplines, specially statics and dynamics, but also material selection, general product development, etc. At the end of this course you will be able to: • Generate alternative configurations...... for mechanisms that follow a particular trajectory, that need to occupy certain positions or that perform special functions using synthesis tools. • Analyze a mechanism from its kinematic characteristics (speed, velocity and acceleration) • Evaluate the best solution from different mechanisms configurations...
Mangiarotti, L
1998-01-01
This book presents in a unified way modern geometric methods in analytical mechanics based on the application of fibre bundles, jet manifold formalism and the related concept of connection. Non-relativistic mechanics is seen as a particular field theory over a one-dimensional base. In fact, the concept of connection is the major link throughout the book. In the gauge scheme of mechanics, connections appear as reference frames, dynamic equations, and in Lagrangian and Hamiltonian formalisms. Inertial forces, energy conservation laws and other phenomena related to reference frames are analyzed;
Kundu, Pijush K; Dowling, David R
2011-01-01
Fluid mechanics, the study of how fluids behave and interact under various forces and in various applied situations-whether in the liquid or gaseous state or both-is introduced and comprehensively covered in this widely adopted text. Revised and updated by Dr. David Dowling, Fluid Mechanics, 5e is suitable for both a first or second course in fluid mechanics at the graduate or advanced undergraduate level. Along with more than 100 new figures, the text has been reorganized and consolidated to provide a better flow and more cohesion of topics.Changes made to the
Powell, John L
2015-01-01
Suitable for advanced undergraduates, this thorough text focuses on the role of symmetry operations and the essentially algebraic structure of quantum-mechanical theory. Based on courses in quantum mechanics taught by the authors, the treatment provides numerous problems that require applications of theory and serve to supplement the textual material.Starting with a historical introduction to the origins of quantum theory, the book advances to discussions of the foundations of wave mechanics, wave packets and the uncertainty principle, and an examination of the Schrödinger equation that includ
Lenarcic, Jadran; Stanišić, Michael M
2013-01-01
This book provides a comprehensive introduction to the area of robot mechanisms, primarily considering industrial manipulators and humanoid arms. The book is intended for both teaching and self-study. Emphasis is given to the fundamentals of kinematic analysis and the design of robot mechanisms. The coverage of topics is untypical. The focus is on robot kinematics. The book creates a balance between theoretical and practical aspects in the development and application of robot mechanisms, and includes the latest achievements and trends in robot science and technology.
Gross, Dietmar; Schröder, Jörg; Wall, Wolfgang A; Rajapakse, Nimal
Statics is the first volume of a three-volume textbook on Engineering Mechanics. The authors, using a time-honoured straightforward and flexible approach, present the basic concepts and principles of mechanics in the clearest and simplest form possible to advanced undergraduate engineering students of various disciplines and different educational backgrounds. An important objective of this book is to develop problem solving skills in a systematic manner. Another aim of this volume is to provide engineering students as well as practising engineers with a solid foundation to help them bridge the gap between undergraduate studies on the one hand and advanced courses on mechanics and/or practical engineering problems on the other. The book contains numerous examples, along with their complete solutions. Emphasis is placed upon student participation in problem solving. The contents of the book correspond to the topics normally covered in courses on basic engineering mechanics at universities and colleges. Now in i...
Perez, Nestor
2017-01-01
The second edition of this textbook includes a refined presentation of concepts in each chapter, additional examples; new problems and sections, such as conformal mapping and mechanical behavior of wood; while retaining all the features of the original book. The material included in this book is based upon the development of analytical and numerical procedures pertinent to particular fields of linear elastic fracture mechanics (LEFM) and plastic fracture mechanics (PFM), including mixed-mode-loading interaction. The mathematical approach undertaken herein is coupled with a brief review of several fracture theories available in cited references, along with many color images and figures. Dynamic fracture mechanics is included through the field of fatigue and Charpy impact testing. Explains computational and engineering approaches for solving crack-related problems using straightforward mathematics that facilitate comprehension of the physical meaning of crack growth processes; Expands computational understandin...
Mandl, F.
1992-07-01
The Manchester Physics Series General Editors: D. J. Sandiford; F. Mandl; A. C. Phillips Department of Physics and Astronomy, University of Manchester Properties of Matter B. H. Flowers and E. Mendoza Optics Second Edition F. G. Smith and J. H. Thomson Statistical Physics Second Edition F. Mandl Electromagnetism Second Edition I. S. Grant and W. R. Phillips Statistics R. J. Barlow Solid State Physics Second Edition J. R. Hook and H. E. Hall Quantum Mechanics F. Mandl Particle Physics Second Edition B. R. Martin and G. Shaw The Physics of Stars Second Edition A. C. Phillips Computing for Scientists R. J. Barlow and A. R. Barnett Quantum Mechanics aims to teach those parts of the subject which every physicist should know. The object is to display the inherent structure of quantum mechanics, concentrating on general principles and on methods of wide applicability without taking them to their full generality. This book will equip students to follow quantum-mechanical arguments in books and scientific papers, and to cope with simple cases. To bring the subject to life, the theory is applied to the all-important field of atomic physics. No prior knowledge of quantum mechanics is assumed. However, it would help most readers to have met some elementary wave mechanics before. Primarily written for students, it should also be of interest to experimental research workers who require a good grasp of quantum mechanics without the full formalism needed by the professional theorist. Quantum Mechanics features: A flow diagram allowing topics to be studied in different orders or omitted altogether. Optional "starred" and highlighted sections containing more advanced and specialized material for the more ambitious reader. Sets of problems at the end of each chapter to help student understanding. Hints and solutions to the problems are given at the end of the book.
Kittell, David
1989-01-01
David Kittell, the father of the discipline, Precision Mechanics, shares the foundation of this science with you in his highly practical and fun to read book, Precision Mechanics. Based on his highly acclaimed course by the same name, first taught at the Perkin-Elmer Technical institute in Norwalk, Connecticut, and later as a short course offered in such places as Bell Labs, SPIE, IEEE, NASA, and several national labs, you will find this book relevant and immediately useful.
Wave Mechanics or Wave Statistical Mechanics
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
By comparison between equations of motion of geometrical optics and that of classical statistical mechanics, this paper finds that there should be an analogy between geometrical optics and classical statistical mechanics instead of geometrical mechanics and classical mechanics. Furthermore, by comparison between the classical limit of quantum mechanics and classical statistical mechanics, it finds that classical limit of quantum mechanics is classical statistical mechanics not classical mechanics, hence it demonstrates that quantum mechanics is a natural generalization of classical statistical mechanics instead of classical mechanics. Thence quantum mechanics in its true appearance is a wave statistical mechanics instead of a wave mechanics.
Ghosh, P K
2014-01-01
Quantum mechanics, designed for advanced undergraduate and graduate students of physics, mathematics and chemistry, provides a concise yet self-contained introduction to the formal framework of quantum mechanics, its application to physical problems and the interpretation of the theory. Starting with a review of some of the necessary mathematics, the basic concepts are carefully developed in the text. After building a general formalism, detailed treatment of the standard material - the harmonic oscillator, the hydrogen atom, angular momentum theory, symmetry transformations, approximation methods, identical particle and many-particle systems, and scattering theory - is presented. The concluding chapter discusses the interpretation of quantum mechanics. Some of the important topics discussed in the book are the rigged Hilbert space, deformation quantization, path integrals, coherent states, geometric phases, decoherene, etc. This book is characterized by clarity and coherence of presentation.
Fitzpatrick, Richard
2015-01-01
Quantum mechanics was developed during the first few decades of the twentieth century via a series of inspired guesses made by various physicists, including Planck, Einstein, Bohr, Schroedinger, Heisenberg, Pauli, and Dirac. All these scientists were trying to construct a self-consistent theory of microscopic dynamics that was compatible with experimental observations. The purpose of this book is to present quantum mechanics in a clear, concise, and systematic fashion, starting from the fundamental postulates, and developing the theory in as logical manner as possible. Topics covered in the book include the fundamental postulates of quantum mechanics, angular momentum, time-dependent and time-dependent perturbation theory, scattering theory, identical particles, and relativistic electron theory.
Helrich, Carl S
2017-01-01
This advanced undergraduate textbook begins with the Lagrangian formulation of Analytical Mechanics and then passes directly to the Hamiltonian formulation and the canonical equations, with constraints incorporated through Lagrange multipliers. Hamilton's Principle and the canonical equations remain the basis of the remainder of the text. Topics considered for applications include small oscillations, motion in electric and magnetic fields, and rigid body dynamics. The Hamilton-Jacobi approach is developed with special attention to the canonical transformation in order to provide a smooth and logical transition into the study of complex and chaotic systems. Finally the text has a careful treatment of relativistic mechanics and the requirement of Lorentz invariance. The text is enriched with an outline of the history of mechanics, which particularly outlines the importance of the work of Euler, Lagrange, Hamilton and Jacobi. Numerous exercises with solutions support the exceptionally clear and concise treatment...
Energy Technology Data Exchange (ETDEWEB)
Raboin, P J
1998-01-01
The Computational Mechanics thrust area is a vital and growing facet of the Mechanical Engineering Department at Lawrence Livermore National Laboratory (LLNL). This work supports the development of computational analysis tools in the areas of structural mechanics and heat transfer. Over 75 analysts depend on thrust area-supported software running on a variety of computing platforms to meet the demands of LLNL programs. Interactions with the Department of Defense (DOD) High Performance Computing and Modernization Program and the Defense Special Weapons Agency are of special importance as they support our ParaDyn project in its development of new parallel capabilities for DYNA3D. Working with DOD customers has been invaluable to driving this technology in directions mutually beneficial to the Department of Energy. Other projects associated with the Computational Mechanics thrust area include work with the Partnership for a New Generation Vehicle (PNGV) for ''Springback Predictability'' and with the Federal Aviation Administration (FAA) for the ''Development of Methodologies for Evaluating Containment and Mitigation of Uncontained Engine Debris.'' In this report for FY-97, there are five articles detailing three code development activities and two projects that synthesized new code capabilities with new analytic research in damage/failure and biomechanics. The article this year are: (1) Energy- and Momentum-Conserving Rigid-Body Contact for NIKE3D and DYNA3D; (2) Computational Modeling of Prosthetics: A New Approach to Implant Design; (3) Characterization of Laser-Induced Mechanical Failure Damage of Optical Components; (4) Parallel Algorithm Research for Solid Mechanics Applications Using Finite Element Analysis; and (5) An Accurate One-Step Elasto-Plasticity Algorithm for Shell Elements in DYNA3D.
Krysinski, Tomasz
2013-01-01
This book presents a study of the stability of mechanical systems, i.e. their free response when they are removed from their position of equilibrium after a temporary disturbance. After reviewing the main analytical methods of the dynamical stability of systems, it highlights the fundamental difference in nature between the phenomena of forced resonance vibration of mechanical systems subjected to an imposed excitation and instabilities that characterize their free response. It specifically develops instabilities arising from the rotor-structure coupling, instability of control systems, the se
Mayer, E
1977-01-01
Mechanical Seals, Third Edition is a source of practical information on the design and use of mechanical seals. Topics range from design fundamentals and test rigs to leakage, wear, friction and power, reliability, and special designs. This text is comprised of nine chapters; the first of which gives a general overview of seals, including various types of seals and their applications. Attention then turns to the fundamentals of seal design, with emphasis on six requirements that must be considered: sealing effectiveness, length of life, reliability, power consumption, space requirements, and c
Davidson, Norman
2003-01-01
Clear and readable, this fine text assists students in achieving a grasp of the techniques and limitations of statistical mechanics. The treatment follows a logical progression from elementary to advanced theories, with careful attention to detail and mathematical development, and is sufficiently rigorous for introductory or intermediate graduate courses.Beginning with a study of the statistical mechanics of ideal gases and other systems of non-interacting particles, the text develops the theory in detail and applies it to the study of chemical equilibrium and the calculation of the thermody
Gallavotti, Giovanni
2012-01-01
This is the English version of a friendly graduate course on Classical Mechanics, containing about 80% of the material I covered during the January-June 1999 semester at IFUG in the Mexican city of Leon. For the Spanish version, see physics/9906066
Drazin, Philip
1987-01-01
Outlines the contents of Volume II of "Principia" by Sir Isaac Newton. Reviews the contributions of subsequent scientists to the physics of fluid dynamics. Discusses the treatment of fluid mechanics in physics curricula. Highlights a few of the problems of modern research in fluid dynamics. Shows that problems still remain. (CW)
Jana, Madhusudan
2015-01-01
Statistical mechanics is self sufficient, written in a lucid manner, keeping in mind the exam system of the universities. Need of study this subject and its relation to Thermodynamics is discussed in detail. Starting from Liouville theorem gradually, the Statistical Mechanics is developed thoroughly. All three types of Statistical distribution functions are derived separately with their periphery of applications and limitations. Non-interacting ideal Bose gas and Fermi gas are discussed thoroughly. Properties of Liquid He-II and the corresponding models have been depicted. White dwarfs and condensed matter physics, transport phenomenon - thermal and electrical conductivity, Hall effect, Magneto resistance, viscosity, diffusion, etc. are discussed. Basic understanding of Ising model is given to explain the phase transition. The book ends with a detailed coverage to the method of ensembles (namely Microcanonical, canonical and grand canonical) and their applications. Various numerical and conceptual problems ar...
Schwabl, Franz
2006-01-01
The completely revised new edition of the classical book on Statistical Mechanics covers the basic concepts of equilibrium and non-equilibrium statistical physics. In addition to a deductive approach to equilibrium statistics and thermodynamics based on a single hypothesis - the form of the microcanonical density matrix - this book treats the most important elements of non-equilibrium phenomena. Intermediate calculations are presented in complete detail. Problems at the end of each chapter help students to consolidate their understanding of the material. Beyond the fundamentals, this text demonstrates the breadth of the field and its great variety of applications. Modern areas such as renormalization group theory, percolation, stochastic equations of motion and their applications to critical dynamics, kinetic theories, as well as fundamental considerations of irreversibility, are discussed. The text will be useful for advanced students of physics and other natural sciences; a basic knowledge of quantum mechan...
Darbyshire, Alan
2010-01-01
Alan Darbyshire's best-selling text book provides five-star high quality content to a potential audience of 13,000 engineering students. It explains the most popular specialist units of the Mechanical Engineering, Manufacturing Engineering and Operations & Maintenance Engineering pathways of the new 2010 BTEC National Engineering syllabus. This challenging textbook also features contributions from specialist lecturers, ensuring that no stone is left unturned.
Socolar, Joshua E. S.; Lubensky, Tom C.; Kane, Charles L.
2017-02-01
We present a model of a mechanical system with a vibrational mode spectrum identical to the spectrum of electronic excitations in a tight-binding model of graphene. The model consists of point masses connected by elastic couplings, called ‘tri-bonds’, that implement certain three-body interactions, which can be tuned by varying parameters that correspond to the relative hopping amplitudes on the different bond directions in graphene. In the mechanical model, this is accomplished by varying the location of a pivot point that determines the allowed rigid rotations of a single tri-bond. The infinite system constitutes a Maxwell lattice, with the number of degrees of freedom equal to the number of constraints imposed by the tri-bonds. We construct the equilibrium and compatibility matrices and analyze the model’s phase diagram, which includes spectra with Weyl points for some placements of the pivot and topologically polarized phases for others. We then discuss the edge modes and associated states of self stress for strips cut from the periodic lattice. Finally, we suggest a physical realization of the tri-bond, which allows access to parameter regimes not available to experiments on (strained) graphene and may be used to create other two-dimensional mechanical metamaterials with different spectral features.
Mandl, Franz
1992-01-01
The Manchester Physics Series General Editors: D. J. Sandiford; F. Mandl; A. C. Phillips Department of Physics and Astronomy, University of Manchester Properties of Matter B. H. Flowers and E. Mendoza Optics Second Edition F. G. Smith and J. H. Thomson Statistical Physics Second Edition F. Mandl Electromagnetism Second Edition I. S. Grant and W. R. Phillips Statistics R. J. Barlow Solid State Physics Second Edition J. R. Hook and H. E. Hall Quantum Mechanics F. Mandl Particle Physics Second Edition B. R. Martin and G. Shaw The Physics of Stars Second Edition A. C. Phillips Computing for Scient
Rae, Alastair I M
2007-01-01
PREFACESINTRODUCTION The Photoelectric Effect The Compton Effect Line Spectra and Atomic Structure De Broglie Waves Wave-Particle Duality The Rest of This Book THE ONE-DIMENSIONAL SCHRÖDINGER EQUATIONS The Time-Dependent Schrödinger Equation The Time-Independent Schrödinger Equation Boundary ConditionsThe Infinite Square Well The Finite Square Well Quantum Mechanical Tunneling The Harmonic Oscillator THE THREE-DIMENSIONAL SCHRÖDINGER EQUATIONS The Wave Equations Separation in Cartesian Coordinates Separation in Spherical Polar Coordinates The Hydrogenic Atom THE BASIC POSTULATES OF QUANTUM MEC
Zagoskin, Alexandre
2015-01-01
Written by Dr Alexandre Zagoskin, who is a Reader at Loughborough University, Quantum Mechanics: A Complete Introduction is designed to give you everything you need to succeed, all in one place. It covers the key areas that students are expected to be confident in, outlining the basics in clear jargon-free English, and then providing added-value features like summaries of key ideas, and even lists of questions you might be asked in your exam. The book uses a structure that is designed to make quantum physics as accessible as possible - by starting with its similarities to Newtonian physics, ra
Gunasekaran, Sharmila; Hussain, Uzair; Kunduri, Hari K.
2016-12-01
The domain of outer communication of five-dimensional asymptotically flat stationary spacetimes may possess nontrivial 2-cycles (bubbles). Spacetimes containing such 2-cycles can have nonzero energy, angular momenta, and charge even in the absence of horizons. A mass variation formula has been established for spacetimes containing bubbles and possibly a black hole horizon. This "first law of black hole and soliton mechanics" contains new intensive and extensive quantities associated with each 2-cycle. We consider examples of such spacetimes for which we explicitly calculate these quantities and show how regularity is essential for the formulas relating them to hold. We also derive new explicit expressions for the angular momenta and charge for spacetimes containing solitons purely in terms of fluxes supporting the bubbles.
Gunasekaran, Sharmila; Kunduri, Hari K
2016-01-01
The domain of outer communication of five-dimensional asymptotically flat stationary spacetimes may possess non-trivial 2-cycles (bubbles). Spacetimes containing such 2-cycles can have non-zero energy, angular momenta, and charge even in the absence of horizons. A mass variation formula has been established for spacetimes containing bubbles and possibly a black hole horizon. This `first law of black hole and soliton mechanics' contains new intensive and extensive quantities associated to each 2-cycle. We consider examples of such spacetimes for which we explicitly calculate these quantities and show how regularity is essential for the formulae relating them to hold. We also derive new explicit expressions for the angular momenta and charge for spacetimes containing solitons purely in terms of fluxes supporting the bubbles.
Shannon, John L., Jr.
1986-01-01
The application of fracture mechanics to the design of ceramic structures will require the precise measurement of crack growth and fracture resistance of these materials over their entire range of anticipated service temperatures and standardized test methods for making such measurements. The development of a standard test for measuring the plane strain fracture toughness is sought. Stress intensity factor coefficients were determined for three varieties of chevron-notch specimens, and fracture toughness measurements were made on silicon nitrides, silicon carbides, and aluminum oxides to assess the performance of each specimen variety. It was determined that silicon nitride and silicon carbides have flat crack growth resistance curves, but aluminum oxide does not. Additionally, batch-to-batch differences were noticed for the aluminum oxide. Experiments are continuing to explain the rising crack growth resistance and batch-to-batch variations for the aluminum oxide.
Kock, L.J.
1959-09-22
A device is presented for loading and unloading fuel elements containing material fissionable by neutrons of thermal energy. The device comprises a combination of mechanical features Including a base, a lever pivotally attached to the base, an Indexing plate on the base parallel to the plane of lever rotation and having a plurality of apertures, the apertures being disposed In rows, each aperture having a keyway, an Index pin movably disposed to the plane of lever rotation and having a plurality of apertures, the apertures being disposed in rows, each aperture having a keyway, an index pin movably disposed on the lever normal to the plane rotation, a key on the pin, a sleeve on the lever spaced from and parallel to the index pin, a pair of pulleys and a cable disposed between them, an open collar rotatably attached to the sleeve and linked to one of the pulleys, a pin extending from the collar, and a bearing movably mounted in the sleeve and having at least two longitudinal grooves in the outside surface.
Barron, Daniel R. (Inventor); Jasulaitis, Vytas (Inventor); Morrill, Brion F. (Inventor)
1995-01-01
Apparatus is described for automatically mating a pair of connectors and protecting them prior to mating, which minimizes weight and uses relatively simple and reliable mechanisms. Lower and upper connectors (24, 26) are held in lower and upper parts (14, 16) of a housing, with the upper connector mounted on a carrier (32) that is motor driven to move down and mate the connectors. A pair of movable members (36, 38) serve as shields, as coarse alignment aids, and as force transmitters. The movable members are pivotally mounted at the bottom of the upper housing, and as the carrier moves down it pivots the members out of the way. The movable members have socket elements (116) that closely receive pin elements (120) on the lower housing part, to coarsely align the connectors and to react mating and unmating forces between the housings. The carrier has a pair of plate portions (60, 62) with slots (64), and the movable members have cam followers engaged with the slot walls, to move the members with precision. The carrier plate-like portions engage follower members (82) that pivot open lower shield parts (44, 46) covering the lower connector, which is mounted on four stacks of Belleville washers (142).
Energy Technology Data Exchange (ETDEWEB)
Shook, Richard; /Marquette U. /SLAC
2010-08-25
The particle beam of the SXR (soft x-ray) beam line in the LCLS (Linac Coherent Light Source) has a high intensity in order to penetrate through samples at the atomic level. However, the intensity is so high that many experiments fail because of severe damage. To correct this issue, attenuators are put into the beam line to reduce this intensity to a level suitable for experimentation. Attenuation is defined as 'the gradual loss in intensity of any flux through a medium' by [1]. It is found that Beryllium and Boron Carbide can survive the intensity of the beam. At very thin films, both of these materials work very well as filters for reducing the beam intensity. Using a total of 12 filters, the first 9 being made of Beryllium and the rest made of Boron Carbide, the beam's energy range of photons can be attenuated between 800 eV and 9000 eV. The design of the filters allows attenuation for different beam intensities so that experiments can obtain different intensities from the beam if desired. The step of attenuation varies, but is relative to the thickness of the filter as a power function of 2. A relationship for this is f(n) = x{sub 0}2{sup n} where n is the step of attenuation desired and x{sub 0} is the initial thickness of the material. To allow for this desired variation, a mechanism must be designed within the test chamber. This is visualized using a 3D computer aided design modeling tool known as Solid Edge.
Mechanism of mechanical activation for sulfide ores
Institute of Scientific and Technical Information of China (English)
HU Hui-ping; CHEN Qi-yuan; YIN Zhou-lan; HE Yue-hui; HUANG Bai-yun
2007-01-01
Structural changes for mechanically activated pyrite, sphalerite, galena and molybdenite with or without the exposure to ambient air, were systematically investigated using X-ray diffraction analysis(XRD), particle size analysis, gravimetrical method, X-ray photo-electron spectroscopy(XPS) and scanning electron microscopy(SEM), respectively. Based on the above structural changes for mechanically activated sulfide ores and related reports by other researchers, several qualitative rules of the mechanisms and the effects of mechanical activation for sulfide ores are obtained. For brittle sulfide ores with thermal instability, and incomplete cleavage plane or extremely incomplete cleavage plane, the mechanism of mechanical activation is that a great amount of surface reactive sites are formed during their mechanical activation. The effects of mechanical activation are apparent. For brittle sulfide ores with thermal instability, and complete cleavage plane, the mechanism of mechanical activation is that a great amount of surface reactive sites are formed, and lattice deformation happens during their mechanical activation. The effects of mechanical activation are apparent. For brittle sulfide ores with excellent thermal stability, and complete cleavage plane, the mechanism of mechanical activation is that lattice deformation happens during their mechanical activation. The effects of mechanical activation are apparent. For sulfide ores with high toughness, good thermal stability and very excellent complete cleavage plane, the mechanism of mechanical activation is that lattice deformation happens during their mechanical activation, but the lattice deformation ratio is very small. The effects of mechanical activation are worst.
Institute of Scientific and Technical Information of China (English)
李子丰
2013-01-01
在旋转问题中，坐标系的选取至关重要，否则会因角速度测量不准而出现错误。旋转问题一级近似惯性坐标系，应该选取比被绕行物体高一级的天体引力场：（1）一般的旋转问题--固定在地球上的直角坐标系；（2）卫星绕地球旋转问题--日心-地心直角坐标系；（3）地球绕太阳旋转问题--银河系心-日心直角坐标系。在天体物理学中，质量计算不准和旋转角速度测量不准导致黑洞猜想。%Selection of the coordinate system is essential for rotate problem.Otherwise,mistakes may occur due to inaccurate measurement of angular speed. Approximate inertial coordinate system selections for rotate problems should be the gravitational field of a celestial body higher than the object being rotated:(1) the earth fixed Cartesian coordinate system for normal rotation problem;(2) heliocentric-geocentric Cartesian coordinate system for satellites orbiting the earth;(3) the Galaxy Heart-heliocentric Cartesian coordinates for Earth's rotation around the sun.In astrophysics,mass calculation error and angular velocity measurement error lead to a black hole conjecture.
k-Nearest Neighbors for automated classification of celestial objects
Institute of Scientific and Technical Information of China (English)
LI LiLi; ZHANG YanXia; ZHAO YongHeng
2008-01-01
The nearest neighbors (NNs) classifiers, especially the k-Nearest Neighbors (kNNs) algorithm, are among the simplest and yet most efficient classification rules and widely used in practice. It is a nonparametric method of pattern recognition. In this paper, k-Nearest Neighbors, one of the most commonly used machine learning methods, work in automatic classification of multi-wavelength astronomical objects. Through the experiment, we conclude that the running speed of the kNN classier is rather fast and the classification accuracy is up to 97.73%. As a result, it is efficient and applicable to discriminate active objects from stars and normal galaxies with this method. The classifiers trained by the kNN method can be used to solve the automated classification problem faced by astronomy and the virtual observatory (VO).
The astronomer Jules Janssen a globetrotter of celestial physics
Launay, Françoise
2012-01-01
Every aspect of the personality of Janssen (1824—1907) – that D’Artagnan of science, this bard of the Sun, and this audacious master builder – is covered here by Françoise Launay, his attentive and equally erudite biographer. A physicist, inventor and builder, Janssen was guided by his energy and curiosity. His research followed two directions: on the one hand the atmospheres of the Earth and the Sun, and on the other, two techniques: spectroscopy and photography. Among his numerous voyages across the globe, he went to Japan in 1874 to follow the transit of Venus in front of the Sun, the same year in which he invented his famous photographic revolver, which was, in truth, a great technical success. To observe the Sun during total eclipses he traveled to the Indies in 1868, to Oran in 1870 (escaping from besieged Paris by balloon!), returned to India in 1871, left for Siam in 1875 and, in 1883, for an island in the Pacific. One can thus understand why Henriette often complained of the solitude in whic...
Celestial messengers. Cosmic rays. The story of a scientific adventure
Energy Technology Data Exchange (ETDEWEB)
Bertolotti, Mario [Roma Univ. (Italy). Dipt. die Scienze di Base e Applicate per l' Ingegneria (SBAI)
2013-07-01
The book describes from a historical point of view how cosmic rays were discovered. The book describes the research in cosmic rays. The main focus is on how the knowledge was gained, describing the main experiments and the conclusions drawn. Biographical sketches of main researchers are provided. Cosmic rays have an official date of discovery which is linked to the famous balloon flights of the Austrian physicist Hess in 1912. The year 2012 can therefore be considered the centenary of the discovery.
Celestial n-Body Coupling in the Lunar Orbit Theory
Tsui, K. H.
2000-09-01
Making use of the fact that, in the solar system, the angular momentum is carried predominantly by the planets while the mass is beared almost entirely by the Sun, an iterative scheme is devised to solve approximately the n-body contributions of the lunar orbit problem. The scheme envisages the Moon-Earth-Sun three-body subsystem as being nested in the grand Earth-Jupiter-Sun system. In the planetocentric representation, the orbital motion of the Sun about the solar system center of mass is transmitted to the third body via the second primary body in both the grand and nested three-body systems.
COSMIC NEWS - NEW DISCOVERIES IN CELESTIAL BODIES IN 1965,
ASTRONOMY, REPORTS), COMETS, GALAXIES, STARS, X RAYS, EXTRATERRESTRIAL RADIO WAVES, SPECTRUM SIGNATURES, PLUTO( PLANET ), MARS( PLANET ), MERCURY ( PLANET ), MOON, PLANETARY ATMOSPHERES, SURFACE PROPERTIES, CHINA
Celestial revolutionary Copernicus, the man and his universe
Freely, John
2014-01-01
In the spring of 1500, at the apex of the Renaissance, a papal secretary to the Borgia Pope, Alexander VI, wrote that ""All the world is in Rome."" Though no one knew it at the time, this included a young scholar by the name of Nicolaus Copernicus who would one day change the world.One of the greatest polymaths of his or any age - linguist, lawyer, doctor, diplomat, politician, mathematician, scientist, astronomer, artist, cleric - Copernicus gave the world arguably the most important scientific discovery of the modern era: that earth and the planets revolve around the sun and that the earth r
Celestial symbolism in the Vučedol culture
Directory of Open Access Journals (Sweden)
Aleksandar Durman
2001-12-01
Full Text Available The article presents the Vučedol Culture conception of the world, as shown on their vessels, particularly the terrines and the vessels developed from them – referred to as censers. They had more of a ritual than a practical role. Particular attention is drawn to the pot with the calendar image.
The Theme of Celestial Bodies in Armenian Lullabies
Hakobyan, Ani
2016-12-01
Folk art is representing the type and the mentality of the nation. People's perceptions and understanding of life, the universe and the world around them are reflected in it. In folk songs coming from the times before Christianity and preserved until now there are many cosmic bodies commemorations and many attempts to consider man as heliocentric and important phenomenon. In this case, we focus on the presence of the sun, the moon and stars in one of the most interesting genres of Armenian folk music - lullabies. This article is meant to represent the ancient Pythagorean theory of cosmic origins of music and coming back to the mentioned genre of the folk art it is also showing the imaging of cosmic bodies on recorded samples of Armenian lullabies of various areas and provinces.
Recent results on celestial gamma radiation from SMM
Share, Gerald H.
1991-01-01
Observations made by the Gamma Ray Spectrometer on board the SMM are described. Recent results reported include observations and analyses of gamma-ray lines from Co-56 produced in supernovae, observations of the temporal variation of the 511 keV line observed during Galactic center transits, and measurements of the diffuse Galactic spectrum from 0.3 to 8.5 MeV. The work in progress includes measurements of the distribution of Galactic Al-26, observations to place limits on Galactic Ti-44 and Fe-60 and on Be-7 produced in novae, and searches for a characteristic gamma-ray emission from pair plasmas, a 2.223 MeV line emission, limits on deexcitation lines from interstellar C and O, and gamma-ray bursts.
Scheduling observations of celestial objects for Earth observing sensor calibration
Wilson, Truman; Xiong, Xiaoxiong
2016-10-01
Radiometric calibration of Earth-observing satellite sensors is critical for tracking on-orbit gain changes throughout the satellite's mission. The Moon, being a stable, well-characterized radiometric target, has been used effectively for tracking the relative gain changes of the reflective solar bands for the Moderate Resolution Imaging Spectroradiometer (MODIS) on board EOS AM-1 (Terra) and PM-1 (Aqua). The Moon is viewed through the MODIS space-view port, and the relative phase of the Moon is restricted to within 0.5 degrees of a chosen target phase to increase the accuracy of the calibration. These geometric restrictions require spacecraft maneuvers in order to bring space-view port into proper alignment with the position of the Moon when the phase requirement is met. In this paper, we describe a versatile tool for scheduling such maneuvers based on the required geometry and lunar phase restrictions for a general spacecraft bound instrument. The results of the scheduling tool have been verified using lunar images from Aqua and Terra MODIS after a scheduled roll maneuver was performed. This tool has also been tested for the Visible Infrared Imaging Radiometer Suite (VIIRS) and the Advanced Technology Microwave Sounder on-board the Suomi-NPP spacecraft. As an extension of this work, we have also developed a tool for scheduling views of bright stars. These stars provide another well-characterized radiometric source that can be used for sensor calibration. This tool has been implemented to determine the times in which a chosen star can be viewed by the high gain stages of the day/night band for the VIIRS instrument.
The Mechanics of Mechanical Watches and Clocks
Du, Ruxu
2013-01-01
"The Mechanics of Mechanical Watches and Clocks" presents historical views and mathematical models of mechanical watches and clocks. Although now over six hundred years old, mechanical watches and clocks are still popular luxury items that fascinate many people around the world. However few have examined the theory of how they work as presented in this book. The illustrations and computer animations are unique and have never been published before. It will be of significant interest to researchers in mechanical engineering, watchmakers and clockmakers, as well as people who have an engineering background and are interested in mechanical watches and clocks. It will also inspire people in other fields of science and technology, such as mechanical engineering and electronics engineering, to advance their designs. Professor Ruxu Du works at the Chinese University of Hong Kong, China. Assistant Professor Longhan Xie works at the South China University of Technology, China.
Calendars with Olympiad display and eclipse prediction on the Antikythera Mechanism.
Freeth, Tony; Jones, Alexander; Steele, John M; Bitsakis, Yanis
2008-07-31
Previous research on the Antikythera Mechanism established a highly complex ancient Greek geared mechanism with front and back output dials. The upper back dial is a 19-year calendar, based on the Metonic cycle, arranged as a five-turn spiral. The lower back dial is a Saros eclipse-prediction dial, arranged as a four-turn spiral of 223 lunar months, with glyphs indicating eclipse predictions. Here we add surprising findings concerning these back dials. Though no month names on the Metonic calendar were previously known, we have now identified all 12 months, which are unexpectedly of Corinthian origin. The Corinthian colonies of northwestern Greece or Syracuse in Sicily are leading contenders-the latter suggesting a heritage going back to Archimedes. Calendars with excluded days to regulate month lengths, described in a first century bc source, have hitherto been dismissed as implausible. We demonstrate their existence in the Antikythera calendar, and in the process establish why the Metonic dial has five turns. The upper subsidiary dial is not a 76-year Callippic dial as previously thought, but follows the four-year cycle of the Olympiad and its associated Panhellenic Games. Newly identified index letters in each glyph on the Saros dial show that a previous reconstruction needs modification. We explore models for generating the unusual glyph distribution, and show how the eclipse times appear to be contradictory. We explain the four turns of the Saros dial in terms of the full moon cycle and the Exeligmos dial as indicating a necessary correction to the predicted eclipse times. The new results on the Metonic calendar, Olympiad dial and eclipse prediction link the cycles of human institutions with the celestial cycles embedded in the Mechanism's gearwork.
Yatawatta, S.; de Bruyn, A. G.; Brentjens, M. A.; Labropoulos, P.; Pandey, V. N.; Kazemi, S.; Zaroubi, S.; Koopmans, L. V. E.; Offringa, A. R.; Jelic, V.; Rubi, O. Martinez; Veligatla, V.; Wijnholds, S. J.; Brouw, W. N.; Bernardi, G.; Ciardi, B.; Daiboo, S.; Harker, G.; Schaye, J.; Thomas, R.; Vedantham, H.; Chapman, E.; Abdalla, F. B.; Alexov, A.; Anderson, J.; Avruch, I. M.; Batejat, F.; Bell, M. E.; Bell, M. R.; Bentum, M.; Best, P.; Bonafede, A.; Bregman, J.; Breitling, F.; van de Brink, R. H.; Broderick, J. W.; Brueggen, M.; Conway, J.; de Gasperin, F.; de Geus, E.; Duscha, S.; Falcke, H.; Fallows, R. A.; Ferrari, C.; Frieswijk, W.; Garrett, M. A.; Griessmeier, J. M.; Gunst, A. W.; Hassall, T. E.; Hessels, J. W. T.; Hoeft, M.; Iacobelli, M.; Juette, E.; Karastergiou, A.; Kondratiev, V. I.; Kramer, M.; Kuniyoshi, M.; Kuper, G.; van Leeuwen, J.; Maat, P.; Mann, G.; McKean, J. P.; Mevius, M.; Mol, J.D.; Munk, H.; Nijboer, R.; Noordam, J. E.; Norden, M. J.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Rottgering, H. J. A.; Sluman, J.; Smirnov, O.; Stappers, B.; Steinmetz, M.; Tagger, M.; Tang, Y.; Tasse, C.; ter Veen, S.; Vermeulen, R.; van Weeren, R. J.; Wise, M.; Wucknitz, O.; Zarka, P.; Mellema, G.
2013-01-01
Aims: The aim of the LOFAR epoch of reionization (EoR) project is to detect the spectral fluctuations of the redshifted HI 21 cm signal. This signal is weaker by several orders of magnitude than the astrophysical foreground signals and hence, in order to achieve this, very long integrations, accurat
Mechanical engineering education
Davim, J Paulo
2012-01-01
Mechanical Engineering is defined nowadays as a discipline "which involves the application of principles of physics, design, manufacturing and maintenance of mechanical systems". Recently, mechanical engineering has also focused on some cutting-edge subjects such as nanomechanics and nanotechnology, mechatronics and robotics, computational mechanics, biomechanics, alternative energies, as well as aspects related to sustainable mechanical engineering.This book covers mechanical engineering higher education with a particular emphasis on quality assurance and the improvement of academic
Mechanical engineer's handbook
Marghitu, Dan B
2001-01-01
The Mechanical Engineer's Handbook was developed and written specifically to fill a need for mechanical engineers and mechanical engineering students throughout the world. With over 1000 pages, 550 illustrations, and 26 tables the Mechanical Engineer's Handbook is very comprehensive, yet affordable, compact, and durable. The Handbook covers all major areas of mechanical engineering with succinct coverage of the definitions, formulas, examples, theory, proofs, and explanations of all principle subject areas. The Handbook is an essential, practical companion for all mechanic
Song, Yuntao; Du, Shijun
2013-01-01
Tokamak Engineering Mechanics offers concise and thorough coverage of engineering mechanics theory and application for tokamaks, and the material is reinforced by numerous examples. Chapter topics include general principles, static mechanics, dynamic mechanics, thermal fluid mechanics and multiphysics structural mechanics of tokamak structure analysis. The theoretical principle of the design and the methods of the analysis for various components and load conditions are presented, while the latest engineering technologies are also introduced. The book will provide readers involved in the study
2014-01-01
Advances in Applied Mechanics draws together recent significant advances in various topics in applied mechanics. Published since 1948, Advances in Applied Mechanics aims to provide authoritative review articles on topics in the mechanical sciences, primarily of interest to scientists and engineers working in the various branches of mechanics, but also of interest to the many who use the results of investigations in mechanics in various application areas, such as aerospace, chemical, civil, en...
Mostafa, Mahmoud A
2012-01-01
MechanismsDefinitions Degrees of Freedom of Planar Mechanisms Four-Revolute-Pairs Chains Single-Slider Chain Double-Slider Mechanisms Mechanisms with Higher Pairs Compound Mechanisms Special Mechanisms Analytical Position Analysis of Mechanisms Velocities and AccelerationsAbsolute Plane Motion of a Particle Relative Motion Applications to Common Links Analysis of Mechanisms: Graphical Method Method of Instantaneous Centers for Determining the VelocitiesAnalytical Analysis CamsIntroduction Types of Cams Modes of Input/Output Motion Follower Configurations Classes of Cams Spur GearsIntroduction
Analytical mechanics for relativity and quantum mechanics
Johns, Oliver Davis
2011-01-01
Analytical Mechanics for Relativity and Quantum Mechanics is an innovative and mathematically sound treatment of the foundations of analytical mechanics and the relation of classical mechanics to relativity and quantum theory. It is intended for use at the introductory graduate level. A distinguishing feature of the book is its integration of special relativity into teaching of classical mechanics. After a thorough review of the traditional theory, Part II of the book introduces extended Lagrangian and Hamiltonian methods that treat time as a transformable coordinate rather than the fixed parameter of Newtonian physics. Advanced topics such as covariant Langrangians and Hamiltonians, canonical transformations, and Hamilton-Jacobi methods are simplified by the use of this extended theory. And the definition of canonical transformation no longer excludes the Lorenz transformation of special relativity. This is also a book for those who study analytical mechanics to prepare for a critical exploration of quantum...
Robust Design of Sounds in Mechanical Mechanisms
DEFF Research Database (Denmark)
Boegedal Jensen, Annemette; Munch, Natasja; Howard, Thomas J.;
2015-01-01
Current practices for creating a desired sound by a mechanical mechanism are irrelative design-build-test processes. It seems that very little guidance is available relating design to the sound output. The focus of this study was to identify, which parameters that affect the sound output of a click...... mechanism consisting of a toothed rack and a click arm. First several geometries of the teeth and the click arm’s head were investigated to identify the most robust and repeatable design. It was found that a flat surface in the valleys between the teeth is very beneficial in relation to repeatability...... mechanisms....
Current Solid Mechanics Research
DEFF Research Database (Denmark)
Tvergaard, Viggo
2016-01-01
About thirty years ago James Lighthill wrote an essay on “What is Mechanics?” With that he also included some examples of the applications of mechanics. While his emphasis was on fluid mechanics, his own research area, he also included examples from research activities in solid mechanics....
Defense Mechanisms: A Bibliography.
Pedrini, D. T.; Pedrini, Bonnie C.
This bibliography includes studies of defense mechanisms, in general, and studies of multiple mechanisms. Defense mechanisms, briefly and simply defined, are the unconscious ego defendants against unpleasure, threat, or anxiety. Sigmund Freud deserves the clinical credit for studying many mechanisms and introducing them in professional literature.…
Handbook of compliant mechanisms
Howell, Larry L; Olsen, Brian M
2013-01-01
A fully illustrated reference book giving an easy-to-understand introduction to compliant mechanisms A broad compilation of compliant mechanisms to give inspiration and guidance to those interested in using compliant mechanisms in their designs, the Handbook of Compliant Mechanisms includes graphics and descriptions of many compliant mechanisms. It comprises an extensive categorization of devices that can be used to help readers identify compliant mechanisms related to their application. It also provides chapters on the basic background in compliant mechanisms, the categories o
Mechanics and Physics of Precise Vacuum Mechanisms
Deulin, E. A; Panfilov, Yu V; Nevshupa, R. A
2010-01-01
In this book the Russian expertise in the field of the design of precise vacuum mechanics is summarized. A wide range of physical applications of mechanism design in electronic, optical-electronic, chemical, and aerospace industries is presented in a comprehensible way. Topics treated include the method of microparticles flow regulation and its determination in vacuum equipment and mechanisms of electronics; precise mechanisms of nanoscale precision based on magnetic and electric rheology; precise harmonic rotary and not-coaxial nut-screw linear motion vacuum feedthroughs with technical parameters considered the best in the world; elastically deformed vacuum motion feedthroughs without friction couples usage; the computer system of vacuum mechanisms failure predicting. This English edition incorporates a number of features which should improve its usefulness as a textbook without changing the basic organization or the general philosophy of presentation of the subject matter of the original Russian work. Exper...
507 mechanical movements mechanisms and devices
Brown, Henry T
2005-01-01
Epicyclic trains, oblique rollers, trip hammers, and lazy-tongs are among the ingenious mechanisms defined and illustrated in this intriguing collection. Spanning the first century of the Industrial Revolution, this 1868 compilation features simplified, concise illustrations of the mechanisms used in hydraulics, steam engines, pneumatics, presses, horologes, and scores of other machines.The movements of each of the 507 mechanisms are depicted in drawings on the left-hand page, and the facing page presents a brief description of the item's use and operation. Ranging from simple to intricately c
Mechanical engineers' handbook, materials and engineering mechanics
Kutz, Myer
2015-01-01
Full coverage of materials and mechanical design inengineering Mechanical Engineers' Handbook, Fourth Edition provides aquick guide to specialized areas you may encounter in your work,giving you access to the basics of each and pointing you towardtrusted resources for further reading, if needed. The accessibleinformation inside offers discussions, examples, and analyses ofthe topics covered. This first volume covers materials and mechanical design, givingyou accessible and in-depth access to the most common topics you'llencounter in the discipline: carbon and alloy steels, stainlesssteels, a
Rotation Axis Variation Due To Spin Orbit Resonance
Gallavotti, G
1993-01-01
Abstract: rotation axis variation due to spin orbit resonance: conference report; keywords: planetary precession, rigid body, chaos, KAM, Arnold diffusion, averaging, celestial mechanics, classical mechanics, large deviations
Directory of Open Access Journals (Sweden)
Fu Yuhua
2014-06-01
gravitation can be derived, which can be used to solve the problem of advance of planetary perihelion and the problem of deflection of photon around the Sun. Again, according to accurate experimental result, the synthesized gravitational formula (including the effects of other celestial bodies and sunlight pressure for the problem of deflection of photon around the Sun is presented. Unlike the original Newton Mechanics, in New Newton Mechanics, for different problems, may have different laws of motion, different formulas of gravity, as well as different expressions of energy. For example, for the problem of a small ball rolls along the inclined plane, and the problem of advance of planetary perihelion, the two formulas of gravity are completely different.
Directory of Open Access Journals (Sweden)
Wang James HC
2010-07-01
Full Text Available Abstract Cells in the musculoskeletal system are subjected to various mechanical forces in vivo. Years of research have shown that these mechanical forces, including tension and compression, greatly influence various cellular functions such as gene expression, cell proliferation and differentiation, and secretion of matrix proteins. Cells also use mechanotransduction mechanisms to convert mechanical signals into a cascade of cellular and molecular events. This mini-review provides an overview of cell mechanobiology to highlight the notion that mechanics, mainly in the form of mechanical forces, dictates cell behaviors in terms of both cellular mechanobiological responses and mechanotransduction.
Verifiably Truthful Mechanisms
DEFF Research Database (Denmark)
Branzei, Simina; Procaccia, Ariel D.
2015-01-01
It is typically expected that if a mechanism is truthful, then the agents would, indeed, truthfully report their private information. But why would an agent believe that the mechanism is truthful? We wish to design truthful mechanisms, whose truthfulness can be verified efficiently (in...... the computational sense). Our approach involves three steps: (i) specifying the structure of mechanisms, (ii) constructing a verification algorithm, and (iii) measuring the quality of verifiably truthful mechanisms. We demonstrate this approach using a case study: approximate mechanism design without money...
Mechanics of Failure Mechanisms in Structures
Carlson, R L; Craig, J I
2012-01-01
This book focuses on the mechanisms and underlying mechanics of failure in various classes of materials such as metallic, ceramic, polymeric, composite and bio-material. Topics include tensile and compressive fracture, crack initiation and growth, fatigue and creep rupture in metallic materials, matrix cracking and delamination and environmental degradation in polymeric composites, failure of bio-materials such as prosthetic heart valves and prosthetic hip joints, failure of ceramics and ceramic matrix composites, failure of metallic matrix composites, static and dynamic buckling failure, dynamic excitations and creep buckling failure in structural systems. Chapters are devoted to failure mechanisms that are characteristic of each of the materials. The work also provides the basic elements of fracture mechanics and studies in detail several niche topics such as the effects of toughness gradients, variable amplitude loading effects in fatigue, small fatigue cracks, and creep induced brittleness. Furthe...
Mechanically induced gel formation
van Herpt, Jochem T.; Stuart, Marc C. A.; Browne, Wesley R.; Feringa, Ben L.
2013-01-01
Mechanical triggering of gelation of an organic solution by a carbazole-based bisurea organogelator is described. Both the duration of the mechanical stimulation and the gelator concentration control the gelation process and the characteristics of the gel obtained.
Welfare Undominated Groves Mechanisms
Apt, Krzysztof R; Guo, Mingyu; Markakis, Evangelos
2008-01-01
A common objective in mechanism design is to choose the outcome (for example, allocation of resources) that maximizes the sum of the agents' valuations, without introducing incentives for agents to misreport their preferences. The class of Groves mechanisms achieves this; however, these mechanisms require the agents to make payments, thereby reducing the agents' total welfare. In this paper we introduce a measure for comparing two mechanisms with respect to the final welfare they generate. This measure induces a partial order on mechanisms and we study the question of finding minimal elements with respect to this partial order. In particular, we say a non-deficit Groves mechanism is welfare undominated if there exists no other non-deficit Groves mechanism that always has a smaller or equal sum of payments. We focus on two domains: (i) auctions with multiple identical units and unit-demand bidders, and (ii) mechanisms for public project problems. In the first domain we analytically characterize all welfare und...
Vibrating Wingstroke Mechanism Project
National Aeronautics and Space Administration — This proposed work will develop a new method and mechanism for generating wing stroke motion of any shape and orientation. The mechanism will provide power, lift and...
Mechanical restraint in psychiatry
DEFF Research Database (Denmark)
Bak, Jesper; Zoffmann, Vibeke; Sestoft, Dorte Maria;
2014-01-01
PURPOSE: To examine how potential mechanical restraint preventive factors in hospitals are associated with the frequency of mechanical restraint episodes. DESIGN AND METHODS: This study employed a retrospective association design, and linear regression was used to assess the associations. FINDING...
Burst Mechanisms in Hydrodynamics
Knobloch, E
1999-01-01
Different mechanisms believed to be responsible for the generation of bursts in hydrodynamical systems are reviewed and a new mechanism capable of generating regular or irregular bursts of large dynamic range near threshold is described. The new mechanism is present in the interaction between oscillatory modes of odd and even parity in systems of large but finite aspect ratio, and provides an explanation for the bursting behavior observed in binary fluid convection. Additional applications of the new mechanism are proposed.
Programmable mechanical metamaterials.
Florijn, Bastiaan; Coulais, Corentin; van Hecke, Martin
2014-10-24
We create mechanical metamaterials whose response to uniaxial compression can be programmed by lateral confinement, allowing monotonic, nonmonotonic, and hysteretic behavior. These functionalities arise from a broken rotational symmetry which causes highly nonlinear coupling of deformations along the two primary axes of these metamaterials. We introduce a soft mechanism model which captures the programmable mechanics, and outline a general design strategy for confined mechanical metamaterials. Finally, we show how inhomogeneous confinement can be explored to create multistability and giant hysteresis.
Solar array deployment mechanism
Calassa, Mark C.; Kackley, Russell
1995-05-01
This paper describes a Solar Array Deployment Mechanism (SADM) used to deploy a rigid solar array panel on a commercial spacecraft. The application required a deployment mechanism design that was not only lightweight, but also could be produced and installed at the lowest possible cost. This paper covers design, test, and analysis of a mechanism that meets these requirements.
Miller, Glen; And Others, Eds.
1991-01-01
Six theme articles discuss agricultural mechanics and its image problem, its importance, and its relevance to urban mechanization. They stress the need for agricultural mechanics and science in the urban environment for preparation for a variety of careers including landscape technology, environmental technology, energy systems management, and…
Introduction to quantum mechanics
Villaseñor, Eduardo J. S.
2008-01-01
The purpose of this contribution is to give a very brief introduction to Quantum Mechanics for an audience of mathematicians. I will follow Segal's approach to Quantum Mechanics paying special attention to algebraic issues. The usual representation of Quantum Mechanics on Hilbert spaces is also discussed.
DEFF Research Database (Denmark)
Sicart (Vila), Miguel Angel
2008-01-01
This article defins game mechanics in relation to rules and challenges. Game mechanics are methods invoked by agents for interacting with the game world. I apply this definition to a comparative analysis of the games Rez, Every Extend Extra and Shadow of the Colossus that will show the relevance...... of a formal definition of game mechanics. Udgivelsesdato: Dec 2008...
Respiratory mechanics in mechanically ventilated patients.
Hess, Dean R
2014-11-01
Respiratory mechanics refers to the expression of lung function through measures of pressure and flow. From these measurements, a variety of derived indices can be determined, such as volume, compliance, resistance, and work of breathing. Plateau pressure is a measure of end-inspiratory distending pressure. It has become increasingly appreciated that end-inspiratory transpulmonary pressure (stress) might be a better indicator of the potential for lung injury than plateau pressure alone. This has resulted in a resurgence of interest in the use of esophageal manometry in mechanically ventilated patients. End-expiratory transpulmonary pressure might also be useful to guide the setting of PEEP to counterbalance the collapsing effects of the chest wall. The shape of the pressure-time curve might also be useful to guide the setting of PEEP (stress index). This has focused interest in the roles of stress and strain to assess the potential for lung injury during mechanical ventilation. This paper covers both basic and advanced respiratory mechanics during mechanical ventilation.
Energy Technology Data Exchange (ETDEWEB)
NONE
2009-07-01
This paper first reviews proposals for the design of sectoral and related market mechanisms currently debated, both in the UNFCCC negotiations, and in different domestic legislative contexts. Secondly, it addresses the possible principles and technical requirements that Parties may wish to consider as the foundations for further elaboration of the mechanisms. The third issue explored herein is domestic implementation of sectoral market mechanisms by host countries, incentives to move to new market mechanisms, as well as how the transition between current and future mechanisms could be managed.
Mechanical Systems, Classical Models
Teodorescu, Petre P
2009-01-01
This third volume completes the Work Mechanical Systems, Classical Models. The first two volumes dealt with particle dynamics and with discrete and continuous mechanical systems. The present volume studies analytical mechanics. Topics like Lagrangian and Hamiltonian mechanics, the Hamilton-Jacobi method, and a study of systems with separate variables are thoroughly discussed. Also included are variational principles and canonical transformations, integral invariants and exterior differential calculus, and particular attention is given to non-holonomic mechanical systems. The author explains in detail all important aspects of the science of mechanics, regarded as a natural science, and shows how they are useful in understanding important natural phenomena and solving problems of interest in applied and engineering sciences. Professor Teodorescu has spent more than fifty years as a Professor of Mechanics at the University of Bucharest and this book relies on the extensive literature on the subject as well as th...
Mechanisms, Transmissions and Applications
Corves, Burkhard
2012-01-01
The first Workshop on Mechanisms, Transmissions and Applications -- MeTrApp-2011 was organized by the Mechatronics Department at the Mechanical Engineering Faculty, “Politehnica” University of Timisoara, Romania, under the patronage of the IFToMM Technical Committees Linkages and Mechanical Controls and Micromachines. The workshop brought together researchers and students who work in disciplines associated with mechanisms science and offered a great opportunity for scientists from all over the world to present their achievements, exchange innovative ideas and create solid international links, setting the trend for future developments in this important and creative field. The topics treated in this volume are mechanisms and machine design, mechanical transmissions, mechatronic and biomechanic applications, computational and experimental methods, history of mechanism and machine science and teaching methods.
Mechanical Systems, Classical Models
Teodorescu, Petre P
2007-01-01
All phenomena in nature are characterized by motion; this is an essential property of matter, having infinitely many aspects. Motion can be mechanical, physical, chemical or biological, leading to various sciences of nature, mechanics being one of them. Mechanics deals with the objective laws of mechanical motion of bodies, the simplest form of motion. In the study of a science of nature mathematics plays an important role. Mechanics is the first science of nature which was expressed in terms of mathematics by considering various mathematical models, associated to phenomena of the surrounding nature. Thus, its development was influenced by the use of a strong mathematical tool; on the other hand, we must observe that mechanics also influenced the introduction and the development of many mathematical notions. In this respect, the guideline of the present book is precisely the mathematical model of mechanics. A special accent is put on the solving methodology as well as on the mathematical tools used; vectors, ...
Complications of mechanical ventilation
Directory of Open Access Journals (Sweden)
Drašković Biljana
2011-01-01
Full Text Available Mechanical ventilation of the lungs, as an important therapeutic measure, cannot be avoided in critically ill patients. However, when machines take over some of vital functions there is always a risk of complications and accidents. Complications associated with mechanical ventilation can be divided into: 1 airway-associated complications; 2 complications in the response of patients to mechanical ventilation; and 3 complications related to the patient’s response to the device for mechanical ventilation. Complications of artificial airway may be related to intubation and extubation or the endotracheal tube. Complications of mechanical ventilation, which arise because of the patient’s response to mechanical ventilation, may primarily cause significant side effects to the lungs. During the last two decades it was concluded that mechanical ventilation can worsen or cause acute lung injury. Mechanical ventilation may increase the alveolar/capillary permeability by overdistension of the lungs (volutrauma, it can exacerbate lung damage due to the recruitment/derecruitment of collapsed alveoli (atelectrauma and may cause subtle damages due to the activation of inflammatory processes (biotrauma. Complications caused by mechanical ventilation, beside those involving the lungs, can also have significant effects on other organs and organic systems, and can be a significant factor contributing to the increase of morbidity and mortality in critically ill of mechanically ventilated patients. Complications are fortunately rare and do not occur in every patient, but due to their seriousness and severity they require extensive knowledge, experience and responsibility by health-care workers.
Auto Mechanics: Auto Mechanic Service Specialist (Lubrication).
Hoover, Virgil
The unit of individualized learning activities is designed to provide training in the job skill, lubrication, for the prospective auto mechanic service specialist. The materials in the unit are divided into two sections. The developmental, or preliminary phase, for use by the instructor, includes brief descriptions of the job and of the student…
Ambrosio, Alphonso; Blitzer, Leon; Conte, S.D.; Cooper, Donald H.; Dergarabedian, P.; Dethlefsen, D.G.; Lunn, Richard L.; Ireland, Richard O.; Jensen, Arnold A.; Kang, Garfield; Levy, Ezra C.; Liu, Anthony; Marcus, Silvia R.; Mickelwait, A.B.; Moe, Kenneth; Moe, Mildred M.; Pitton, A.R.; Scheuer, Ernest M.; Tompkins, E.H.; Weiser, Peter B.; Whitford, R.K.; Wolverton, R.W.
1961-01-01
This handbook provides parametric data useful both to the space vehicle designer and mission analyst. It provides numerical and analytical relationships between missions and gross vehicle characteristics as a function of performance parameters. The effects of missile constraints and gross guidance limitations plus operational constraints such as launch site location, tracking net location, orbit visibility and mission on trajectory and orbit design parameters are exhibited. The influence of state-of- the-art applications of solar power as compared to future applications of nuclear power on orbit design parameters, such as eclipse time, are among the parameters included in the study. The principal aim, however, is in providing the analyst with useful parametric design information to cover the general area of earth satellite missions in the region of near-earth to cislunar space and beyond and from injection to atmospheric entry and controlled descent. The chapters are organized around the central idea of orbital operations in the 1961-1969 era with emphasis on parametric flight mechanics studies for ascent phase and parking orbits, transfer maneuvers, rendezvous maneuver, operational orbit considerations, and operational orbit control. The results are based almost entirely on the principles of flight and celestial mechanics. Numerous practical examples have been worked out in detail. This is especially important where it has been difficult or impossible to represent all possible variations of the parameters. The handbook contains analytical formulae and sufficient textual material to permit their proper use. The analytic methods consist of both exact and rapid, approximate methods. Scores of tables, working graphs and illustrations amplify the mathematical models which, together with important facts and data, cover the engineering and scientific applications of orbital mechanics. Each of the five major chapters are arranged to provide a rapid review of an entire
Nonholonomic mechanics and control
Murray, RM
2015-01-01
This book explores some of the connections between control theory and geometric mechanics; that is, control theory is linked with a geometric view of classical mechanics in both its Lagrangian and Hamiltonian formulations and in particular with the theory of mechanical systems subject to motion constraints. The synthesis of the topic is appropriate as there is a particularly rich connection between mechanics and nonlinear control theory. The book provides a unified treatment of nonlinear control theory and constrained mechanical systems and illustrates the elegant mathematics behind many simple, interesting, and useful mechanical examples. It is intended for graduate students who wish to learn this subject and researchers in the area who want to enhance their techniques. The book contains sections focusing on physical examples and elementary terms, as well as theoretical sections that use sophisticated analysis and geometry. The first four chapters offer preliminaries and background information, while the...
Tao, Jiaxiang; Li, Yizeng; Vig, Dhruv K.; Sun, Sean X.
2017-03-01
Under the microscope, eukaryotic animal cells can adopt a variety of different shapes and sizes. These cells also move and deform, and the physical mechanisms driving these movements and shape changes are important in fundamental cell biology, tissue mechanics, as well as disease biology. This article reviews some of the basic mechanical concepts in cells, emphasizing continuum mechanics description of cytoskeletal networks and hydrodynamic flows across the cell membrane. We discuss how cells can generate movement and shape changes by controlling mass fluxes at the cell boundary. These mass fluxes can come from polymerization/depolymerization of actin cytoskeleton, as well as osmotic and hydraulic pressure-driven flow of water across the cell membrane. By combining hydraulic pressure control with force balance conditions at the cell surface, we discuss a quantitative mechanism of cell shape and volume control. The broad consequences of this model on cell mechanosensation and tissue mechanics are outlined.
Quantum mechanics in chemistry
Schatz, George C
2002-01-01
Intended for graduate and advanced undergraduate students, this text explores quantum mechanical techniques from the viewpoint of chemistry and materials science. Dynamics, symmetry, and formalism are emphasized. An initial review of basic concepts from introductory quantum mechanics is followed by chapters examining symmetry, rotations, and angular momentum addition. Chapter 4 introduces the basic formalism of time-dependent quantum mechanics, emphasizing time-dependent perturbation theory and Fermi's golden rule. Chapter 5 sees this formalism applied to the interaction of radiation and matt
Equilibrium statistical mechanics
Jackson, E Atlee
2000-01-01
Ideal as an elementary introduction to equilibrium statistical mechanics, this volume covers both classical and quantum methodology for open and closed systems. Introductory chapters familiarize readers with probability and microscopic models of systems, while additional chapters describe the general derivation of the fundamental statistical mechanics relationships. The final chapter contains 16 sections, each dealing with a different application, ordered according to complexity, from classical through degenerate quantum statistical mechanics. Key features include an elementary introduction t
On Noncommutative Classical Mechanics
Djemai, A E F
2003-01-01
In this work, I investigate the noncommutative Poisson algebra of classical observables corresponding to a proposed general Noncommutative Quantum Mechanics, \\cite{1}. I treat some classical systems with various potentials and some Physical interpretations are given concerning the presence of noncommutativity at large scales (Celeste Mechanics) directly tied to the one present at small scales (Quantum Mechanics) and its possible relation with UV/IR mixing.
Lemaire, Maurice
2014-01-01
Science is a quest for certainty, but lack of certainty is the driving force behind all of its endeavors. This book, specifically, examines the uncertainty of technological and industrial science. Uncertainty and Mechanics studies the concepts of mechanical design in an uncertain setting and explains engineering techniques for inventing cost-effective products. Though it references practical applications, this is a book about ideas and potential advances in mechanical science.
Lectures on statistical mechanics
Bowler, M G
1982-01-01
Anyone dissatisfied with the almost ritual dullness of many 'standard' texts in statistical mechanics will be grateful for the lucid explanation and generally reassuring tone. Aimed at securing firm foundations for equilibrium statistical mechanics, topics of great subtlety are presented transparently and enthusiastically. Very little mathematical preparation is required beyond elementary calculus and prerequisites in physics are limited to some elementary classical thermodynamics. Suitable as a basis for a first course in statistical mechanics, the book is an ideal supplement to more convent
Mechanical and Aerospace Engineering
Millsaps, Knox T.; Gordis, J. H.; Brophy, C. M.; Stephens, Sandra
2008-01-01
This brochure explains the Mechanical and Aerospace Engineering program at the Naval Postgraduate School. Sections include: Advancing your career, student research, degree programs, special programs, research and distance learning programs. The Mechanical and Aerospace Engineering (MAE) Department, the founding department of the Naval Postgraduate School in 1909, offers a wide range of graduate degree programs including M.S. and Ph.D., in either Mechanical or Astronautical En...
Equilibrium statistical mechanics
Mayer, J E
1968-01-01
The International Encyclopedia of Physical Chemistry and Chemical Physics, Volume 1: Equilibrium Statistical Mechanics covers the fundamental principles and the development of theoretical aspects of equilibrium statistical mechanics. Statistical mechanical is the study of the connection between the macroscopic behavior of bulk matter and the microscopic properties of its constituent atoms and molecules. This book contains eight chapters, and begins with a presentation of the master equation used for the calculation of the fundamental thermodynamic functions. The succeeding chapters highlight t
Testing Nonassociative Quantum Mechanics.
Bojowald, Martin; Brahma, Suddhasattwa; Büyükçam, Umut
2015-11-27
The familiar concepts of state vectors and operators in quantum mechanics rely on associative products of observables. However, these notions do not apply to some exotic systems such as magnetic monopoles, which have long been known to lead to nonassociative algebras. Their quantum physics has remained obscure. This Letter presents the first derivation of potentially testable physical results in nonassociative quantum mechanics, based on effective potentials. They imply new effects which cannot be mimicked in usual quantum mechanics with standard magnetic fields.
Mechanically reinforced glass beams
DEFF Research Database (Denmark)
Nielsen, Jens Henrik; Olesen, John Forbes
2007-01-01
to breakage without any warning or ductility, which can be catastrophic if no precautions are taken. One aspect of this issue is treated here by looking at the possibility of mechanically reinforcing glass beams in order to obtain ductile failure for such a structural component. A mechanically reinforced...... the mechanical behavior of the beam is explained. Finally, some design criterions for reinforced glass beams are discussed....
Fuzzy clustering of mechanisms
Indian Academy of Sciences (India)
Amitabha Ghosh; Dilip Kumar Pratihar; M V V Amarnath; Guenter Dittrich; Jorg Mueller
2012-10-01
During the course of development of Mechanical Engineering, a large number of mechanisms (that is, linkages to perform various types of tasks) have been conceived and developed. Quite a few atlases and catalogues were prepared by the designers of machines and mechanical systems. However, often it is felt that a clustering technique for handling the list of large number of mechanisms can be very useful,if it is developed based on a scientiﬁc principle. In this paper, it has been shown that the concept of fuzzy sets can be conveniently used for this purpose, if an adequate number of properly chosen attributes (also called characteristics) are identiﬁed. Using two clustering techniques, the mechanisms have been classiﬁed in the present work and in future, it may be extended to develop an expert system, which can automate type synthesis phase of mechanical design. To the best of the authors’ knowledge, this type of clustering of mechanisms has not been attempted before. Thus, this is the ﬁrst attempt to cluster the mechanisms based on some quantitative measures. It may help the engineers to carry out type synthesis of the mechanisms.
Mechanisms for space applications
Meftah, M.; Irbah, A.; Le Letty, R.; Barré, M.; Pasquarella, S.; Bokaie, M.; Bataille, A.; Poiet, G.
2012-06-01
All space instruments contain mechanisms or moving mechanical assemblies that must move (sliding, rolling, rotating, or spinning) and their successful operation is usually mission-critical. Generally, mechanisms are not redundant and therefore represent potential single point failure modes. Several space missions have suffered anomalies or failures due to problems in applying space mechanisms technology. Mechanisms require a specific qualification through a dedicated test campaign. This paper covers the design, development, testing, production, and in-flight experience of the PICARD/SODISM mechanisms. PICARD is a space mission dedicated to the study of the Sun. The PICARD Satellite was successfully launched, on June 15, 2010 on a DNEPR launcher from Dombarovskiy Cosmodrome, near Yasny (Russia). SODISM (SOlar Diameter Imager and Surface Mapper) is a 11 cm Ritchey-Chretien imaging telescope, taking solar images at five wavelengths. SODISM uses several mechanisms (a system to unlock the door at the entrance of the instrument, a system to open/closed the door using a stepper motor, two filters wheels using a stepper motor, and a mechanical shutter). For the fine pointing, SODISM uses three piezoelectric devices acting on the primary mirror of the telescope. The success of the mission depends on the robustness of the mechanisms used and their life.
Goldman, Iosif Ilich; Geilikman, B T
2006-01-01
This challenging book contains a comprehensive collection of problems in nonrelativistic quantum mechanics of varying degrees of difficulty. It features answers and completely worked-out solutions to each problem. Geared toward advanced undergraduates and graduate students, it provides an ideal adjunct to any textbook in quantum mechanics.
Goryachkin's agricultural mechanics
Chinenova, Vera
2016-03-01
The paper contributes to the development of applied mechanics by establishing a new discipline, namely, agricultural mechanics by academician Vasilii Prohorovich Goryachkin (1868-1935) who was an apprentice of Nikolay Yegorovich Zhukovsky and a graduate of the Moscow University (current known as Moscow State University) and the Imperial Higher Technical School.
Sakes, Aimée; Wiel, van der Marleen; Henselmans, Paul W.J.; Leeuwen, van Johan L.; Dodou, Dimitra; Breedveld, Paul
2016-01-01
Background In nature, shooting mechanisms are used for a variety of purposes, including prey capture, defense, and reproduction. This review offers insight into the working principles of shooting mechanisms in fungi, plants, and animals in the light of the specific functional demands that these m
Mechanical ventilation in children.
Kendirli, Tanil; Kavaz, Asli; Yalaki, Zahide; Oztürk Hişmi, Burcu; Derelli, Emel; Ince, Erdal
2006-01-01
Mechanical ventilation can be lifesaving, but > 50% of complications in conditions that require intensive care are related to ventilatory support, particularly if it is prolonged. We retrospectively evaluated the medical records of patients who had mechanical ventilation in the Pediatric Intensive Care Unit (PICU) during a follow-up period between January 2002-May 2005. Medical records of 407 patients were reviewed. Ninety-one patients (22.3%) were treated with mechanical ventilation. Ages of all patients were between 1-180 (median: 8) months. The mechanical ventilation time was 18.8 +/- 14.1 days. Indication of mechanical ventilation could be divided into four groups as respiratory failure (64.8%), cardiovascular failure (19.7%), central nervous system disease (9.8%) and safety airway (5.4%). Tracheostomy was performed in four patients. The complication ratio of mechanically ventilated children was 42.8%, and diversity of complications was as follows: 26.3% atelectasia, 17.5% ventilator-associated pneumonia, 13.1% pneumothorax, 5.4% bleeding, 4.3% tracheal edema, and 2.1% chronic lung disease. The mortality rate of mechanically ventilated patients was 58.3%, but the overall mortality rate in the PICU was 12.2%. In conclusion, there are few published epidemiological data on the follow-up results and mortality in infants and children who are mechanically ventilated.
Mecanica Clasica (Classical Mechanics)
Rosu, H. C.
1999-01-01
First Internet graduate course on Classical Mechanics in Spanish (Castellano). This is about 80% of the material I covered during the January-June 1999 semester at IFUG in the Mexican city of Leon. English and Romanian versions are in (slow) progress and hopefully will be arXived. For a similar course on Quantum Mechanics, see physics/9808031
Mecanica Clasica (Classical Mechanics)
Rosu, H C
1999-01-01
First Internet undergraduate course on Classical Mechanics in Spanish (Castellano). This is about 80% of the material I covered during the January-June 1999 semester at IFUG in the Mexican city of Leon. English and Romanian versions are in (slow) progress and hopefully will be arXived. For a similar course on Quantum Mechanics, see physics/9808031
Infection and inflammatory mechanisms
Van Dyke, Thomas E.; van Winkelhoff, Arie Jan
2013-01-01
This introductory article examines the potential mechanisms that may play a role in the associations between periodontitis and the systemic conditions being considered in the EFP/AAP Workshop in Segovia, Spain. Three basic mechanisms have been postulated to play a role in these interactions; metasta
Institute of Scientific and Technical Information of China (English)
李嘉; 张勇军; 李钦豪; 李琳
2014-01-01
在«太阳系天体相对地球某点的波动式螺线运动(I)»和«太阳系天体相对地球某点的波动式螺线运动(II)»中，推导太阳系天体对地球某点的波动式螺线运动方程。对螺线方程进行分析，并根据傅里叶原理，将各波动方程叠加，并以太阳系天体对地球赤道某点波动式螺线运动方程为例，利用计算机模拟得到各叠加图线，以探讨太阳系天体运动对地球某点的共同影响。模拟结果表明，太阳系天体对地球赤道某点立体波动式螺线叠加后，波形与单个天体类似，仍呈周期性螺线变化，且在三个坐标平面上的投影均为周期性波动，整体传播呈现薄膜状波动面。日月叠加图线与太阳近似，五大行星叠加图线较七大行星规则，五大行星在双波动坐标轴下的波动式螺线叠加在 yz平面的投影在某个阶段非常的密集，之后突然稀疏，七大行星也是，不过五大行星的密集长度比七大行星的长。日月对太阳系行星总体叠加影响不大。%In the thesis of The Undulating Spiral Motion of Celestial Bodies in Solar System Relative to a Certain Point on the Earth (I )and The Undulating Spiral Motion of Celestial Bodies in Solar System Relative to a Certain Point on the Earth (I I ),undulating spiral motion equation of solar system bodies relative to a certain point on the earth has been derived.This thesis will analyze each equation and superimpose the undulating equation based on the Fourier Principle,and then taking the undulating spiral motion equation of solar system bodies relative to a certain point on terrestrial equator for example,use computers simulation to obtain superposition graph to research the common influence of solar system bodies to a certain point on the earth.The simulation result indicates that,after superimposing the stereoscopic undulating spiral of solar system bodies relative to a certain point on terrestrial equator
Directory of Open Access Journals (Sweden)
Tadashi Okazaki
2015-01-01
Full Text Available We consider the multiple M2-branes wrapped on a compact Riemann surface and study the arising quantum mechanics by taking the limit where the size of the Riemann surface goes to zero. The IR quantum mechanical models resulting from the BLG-model and the ABJM-model compactified on a torus are N=16 and N=12 superconformal gauged quantum mechanics. After integrating out the auxiliary gauge fields we find OSp(16|2 and SU(1,1|6 quantum mechanics from the reduced systems. The curved Riemann surface is taken as a holomorphic curve in a Calabi–Yau space to preserve supersymmetry and we present a prescription of the topological twisting. We find the N=8 superconformal gauged quantum mechanics that may describe the motion of two wrapped M2-branes in a K3 surface.
Quantum mechanics for pedestrians
Pade, Jochen
2014-01-01
This book provides an introduction into the fundamentals of non-relativistic quantum mechanics. In Part 1, the essential principles are developed. Applications and extensions of the formalism can be found in Part 2. The book includes not only material that is presented in traditional textbooks on quantum mechanics, but also discusses in detail current issues such as interaction-free quantum measurements, neutrino oscillations, various topics in the field of quantum information as well as fundamental problems and epistemological questions, such as the measurement problem, entanglement, Bell's inequality, decoherence, and the realism debate. A chapter on current interpretations of quantum mechanics concludes the book. To develop quickly and clearly the main principles of quantum mechanics and its mathematical formulation, there is a systematic change between wave mechanics and algebraic representation in the first chapters. The required mathematical tools are introduced step by step. Moreover, the appendix coll...
Chaichian, Masud; Tureanu, Anca
2012-01-01
Mechanics is one of the oldest and at the same time newest disciplines, in the sense that there are methods and principles developed first in mechanics but now widely used in almost all branches of physics: electrodynamics, quantum mechanics, classical and quantum field theory, special and general theory of relativity, etc. More than that, there are some formalisms like Lagrangian and Hamiltonian approaches, which represent the key stone for the development of the above-mentioned disciplines. During the last 20-25 years, classical mechanics has undergone an important revival associated with the progress in non-linear dynamics, applications of Noether’s theorem and the extension of variational principles in various interdisciplinary sciences (for instance, magnetofluid dynamics). Thus, there ought to exist a book concerned with the applied analytical formalism, first developed in the frame of theoretical mechanics, which has proved to be one of the most efficient tools of investigation in the entire arena of...
Quantum mechanics for mathematicians
Takhtajan, Leon A
2008-01-01
This book provides a comprehensive treatment of quantum mechanics from a mathematics perspective and is accessible to mathematicians starting with second-year graduate students. It addition to traditional topics, like classical mechanics, mathematical foundations of quantum mechanics, quantization, and the Schrodinger equation, this book gives a mathematical treatment of systems of identical particles with spin, and it introduces the reader to functional methods in quantum mechanics. This includes the Feynman path integral approach to quantum mechanics, integration in functional spaces, the relation between Feynman and Wiener integrals, Gaussian integration and regularized determinants of differential operators, fermion systems and integration over anticommuting (Grassmann) variables, supersymmetry and localization in loop spaces, and supersymmetric derivation of the Atiyah-Singer formula for the index of the Dirac operator. Prior to this book, mathematicians could find these topics only in physics textbooks ...
Advanced Visual Quantum Mechanics
Thaller, Bernd
2005-01-01
Advanced Visual Quantum Mechanics is a systematic effort to investigate and to teach quantum mechanics with the aid of computer-generated animations. It is a self-contained textbook that combines selected topics from atomic physics (spherical symmetry, the hydrogen atom, and particles with spin) with an introduction to quantum information theory (qubits, EPR paradox, teleportation, quantum computers). It explores relativistic quantum mechanics and the strange behavior of Dirac equation solutions. A series of appendices covers important topics from perturbation and scattering theory. The book places an emphasis on ideas and concepts, with a fair to moderate amount of mathematical rigor. Though this book stands alone, it can also be paired with Thaller Visual Quantum Mechanics to form a comprehensive course in quantum mechanics. The software for the first book earned the European Academic Software Award 2000 for outstanding innovation in its field.
Ahn, Doyeol
2011-01-01
A clear introduction to quantum mechanics concepts Quantum mechanics has become an essential tool for modern engineering, particularly due to the recent developments in quantum computing as well as the rapid progress in optoelectronic devices. Engineering Quantum Mechanics explains the fundamentals of this exciting field, providing broad coverage of both traditional areas such as semiconductor and laser physics as well as relatively new yet fast-growing areas such as quantum computation and quantum information technology. The book begins with basic quantum mechanics, reviewing measurements and probability, Dirac formulation, the uncertainty principle, harmonic oscillator, angular momentum eigenstates, and perturbation theory. Then, quantum statistical mechanics is explored, from second quantization and density operators to coherent and squeezed states, coherent interactions between atoms and fields, and the Jaynes-Cummings model. From there, the book moves into elementary and modern applications, discussing s...
The orbital mechanics of flight mechanics
Dunning, R. S.
1973-01-01
A reference handbook on modern dynamic orbit theory is presented. Starting from the most basic inverse-square law, the law of gravity for a sphere is developed, and the motion of point masses under the influence of a sphere is considered. The reentry theory and the orbital theory are discussed along with the relative motion between two bodies in orbit about the same planet. Relative-motion equations, rectangular coordinates, and the mechanics of simple rigid bodies under the influence of a gravity gradient field are also discussed.
Mechanics, Waves and Thermodynamics
Ranjan Jain, Sudhir
2016-05-01
Figures; Preface; Acknowledgement; 1. Energy, mass, momentum; 2. Kinematics, Newton's laws of motion; 3. Circular motion; 4. The principle of least action; 5. Work and energy; 6. Mechanics of a system of particles; 7. Friction; 8. Impulse and collisions; 9. Central forces; 10. Dimensional analysis; 11. Oscillations; 12. Waves; 13. Sound of music; 14. Fluid mechanics; 15. Water waves; 16. The kinetic theory of gases; 17. Concepts and laws of thermodynamics; 18. Some applications of thermodynamics; 19. Basic ideas of statistical mechanics; Bibliography; Index.
Energy Technology Data Exchange (ETDEWEB)
Kapustin, Anton [California Institute of Technology, Pasadena, California 91125 (United States)
2013-06-15
We formulate physically motivated axioms for a physical theory which for systems with a finite number of degrees of freedom uniquely lead to quantum mechanics as the only nontrivial consistent theory. Complex numbers and the existence of the Planck constant common to all systems arise naturally in this approach. The axioms are divided into two groups covering kinematics and basic measurement theory, respectively. We show that even if the second group of axioms is dropped, there are no deformations of quantum mechanics which preserve the kinematic axioms. Thus, any theory going beyond quantum mechanics must represent a radical departure from the usual a priori assumptions about the laws of nature.
Institute of Scientific and Technical Information of China (English)
WU Ning
2006-01-01
It is well known that energy-momentum is the source of gravitational field. For a long time, it is generally believed that only stars with huge masses can generate strong gravitational field. Based on the unified theory of gravitational interactions and electromagnetic interactions, a new mechanism of the generation of gravitational field is studied. According to this mechanism, in some special conditions, electromagnetic energy can be directly converted into gravitational energy, and strong gravitational field can be generated without massive stars. Gravity impulse found in experiments is generated by this mechanism.
Analytical elements of mechanics
Kane, Thomas R
2013-01-01
Analytical Elements of Mechanics, Volume 1, is the first of two volumes intended for use in courses in classical mechanics. The books aim to provide students and teachers with a text consistent in content and format with the author's ideas regarding the subject matter and teaching of mechanics, and to disseminate these ideas. The book opens with a detailed exposition of vector algebra, and no prior knowledge of this subject is required. This is followed by a chapter on the topic of mass centers, which is presented as a logical extension of concepts introduced in connection with centroids. A
Chaves, Eduardo W V
2013-01-01
This publication is aimed at students, teachers, and researchers of Continuum Mechanics and focused extensively on stating and developing Initial Boundary Value equations used to solve physical problems. With respect to notation, the tensorial, indicial and Voigt notations have been used indiscriminately. The book is divided into twelve chapters with the following topics: Tensors, Continuum Kinematics, Stress, The Objectivity of Tensors, The Fundamental Equations of Continuum Mechanics, An Introduction to Constitutive Equations, Linear Elasticity, Hyperelasticity, Plasticity (small and large deformations), Thermoelasticity (small and large deformations), Damage Mechanics (small and large deformations), and An Introduction to Fluids. Moreover, the text is supplemented with over 280 figures, over 100 solved problems, and 130 references.
Applications in solid mechanics
DEFF Research Database (Denmark)
Ølgaard, Kristian Breum; Wells, Garth N.
2012-01-01
Problems in solid mechanics constitute perhaps the largest field of application of finite element methods. The vast majority of solid mechanics problems involve the standard momentum balance equation, posed in a Lagrangian setting, with different models distinguished by the choice of nonlinear...... or linearized kinematics, and the constitutive model for determining the stress. For some common models, the constitutive relationships are rather complex. This chapter addresses a number of canonical solid mechanics models in the context of automated modeling, and focuses on some pertinent issues that arise...
Mechanics of Generalized Continua
Maugin, Gerard A
2010-01-01
In their 1909 publication "Theorie des corps deformables", Eugene and Francois Cosserat made a historic contribution to materials science by establishing the fundamental principles of the mechanics of generalized continua. The chapters collected in this volume showcase the many areas of continuum mechanics that grew out of the foundational work of the Cosserat brothers. The included contributions provide a detailed survey of the most recent theoretical developments in the field of generalized continuum mechanics. The diverse topics covered include: the properties of Cosserat media, m
Spletzer, Barry L.; Martinez, Michael A.; Marron, Lisa C.
2012-11-13
A rotary mechanical latch for positive latching and unlatching of a rotary device with a latchable rotating assembly having a latching gear that can be driven to latched and unlatched states by a drive mechanism such as an electric motor. A cam arm affixed to the latching gear interfaces with leading and trailing latch cams affixed to a flange within the drive mechanism. The interaction of the cam arm with leading and trailing latch cams prevents rotation of the rotating assembly by external forces such as those due to vibration or tampering.
Sarkar, Malay; Niranjan, N; Banyal, PK
2017-01-01
Oxygen is an essential element for life and without oxygen humans can survive for few minutes only. There should be a balance between oxygen demand and delivery in order to maintain homeostasis within the body. The two main organ systems responsible for oxygen delivery in the body and maintaining homeostasis are respiratory and cardiovascular system. Abnormal function of any of these two would lead to the development of hypoxemia and its detrimental consequences. There are various mechanisms of hypoxemia but ventilation/perfusion mismatch is the most common underlying mechanism of hypoxemia. The present review will focus on definition, various causes, mechanisms, and approach of hypoxemia in human. PMID:28144061
Dirac, Paul A M
2001-01-01
The author of this concise, brilliant series of lectures on mathematical methods in quantum mechanics was one of the shining intellects in the field, winning a Nobel prize in 1933 for his pioneering work in the quantum mechanics of the atom. Beyond that, he developed the transformation theory of quantum mechanics (which made it possible to calculate the statistical distribution of certain variables), was one of the major authors of the quantum theory of radiation, codiscovered the Fermi-Dirac statistics, and predicted the existence of the positron.The four lectures in this book were delivered
Mechanical engineers data handbook
Carvill, James
1994-01-01
This text provides the student and professional mechanical engineer with a reference text of an essentially practical nature. It is uncluttered by text, and extensive use of illustrations and tables provide quick and clear access to information. It alsoincludes examples of detailed calculations on many of the applications of technology used by mechanical and production engineers, draughtsmen and engineering designers.Although mainly intended for those studying and practising mechanical engineering, a glance at the contents will show that it is also useful to those in related br
Michell, S J
2013-01-01
Fluid and Particle Mechanics provides information pertinent to hydraulics or fluid mechanics. This book discusses the properties and behavior of liquids and gases in motion and at rest. Organized into nine chapters, this book begins with an overview of the science of fluid mechanics that is subdivided accordingly into two main branches, namely, fluid statics and fluid dynamics. This text then examines the flowmeter devices used for the measurement of flow of liquids and gases. Other chapters consider the principle of resistance in open channel flow, which is based on improper application of th
Facing quantum mechanical reality.
Rohrlich, F
1983-09-23
Two recent precision experiments provide conclusive evidence against any local hidden variables theory and in favor of standard quantum mechanics. Therefore the epistemology and the ontology of quantum mechanics must now be taken more seriously than ever before. The consequences of the standard interpretation of quantum mechanics are summarized in nontechnical language. The implications of the finiteness of Planck's constant (h > 0) for the quantum world are as strange as the implications of the finiteness of the speed of light (c < infinity for space and time in relativity theory. Both lead to realities beyond our common experience that cannot be rejected.
Mechanics classical and quantum
Taylor, T T
2015-01-01
Mechanics: Classical and Quantum explains the principles of quantum mechanics via the medium of analytical mechanics. The book describes Schrodinger's formulation, the Hamilton-Jacobi equation, and the Lagrangian formulation. The author discusses the Harmonic Oscillator, the generalized coordinates, velocities, as well as the application of the Lagrangian formulation to systems that are partially or entirely electromagnetic in character under certain conditions. The book examines waves on a string under tension, the isothermal cavity radiation, and the Rayleigh-Jeans result pertaining to the e
Mechanical design engineering handbook
Childs, Peter R N
2013-01-01
Mechanical Design Engineering Handbook is a straight-talking and forward-thinking reference covering the design, specification, selection, use and integration of machine elements fundamental to a wide range of engineering applications. Develop or refresh your mechanical design skills in the areas of bearings, shafts, gears, seals, belts and chains, clutches and brakes, springs, fasteners, pneumatics and hydraulics, amongst other core mechanical elements, and dip in for principles, data and calculations as needed to inform and evaluate your on-the-job decisions. Covering the full spectrum
The Mechanisms of Involuntary Attention
Prinzmetal, William; Ha, Ruby; Khani, Aniss
2010-01-01
We tested 3 mechanisms of involuntary attention: (1) a perceptual enhancement mechanism, (2) a response-decision mechanism, and (3) a serial-search mechanism. Experiment 1 used a response deadline technique to compare the perceptual enhancement and the decision mechanisms and found evidence consistent with the decision mechanism. Experiment 2 used…
ELECTROMAGNETIC RELEASE MECHANISM
Michelson, C.
1960-09-13
An electromagnetic release mechanism is offered that may be used, for example, for supporting a safety rod for a nuclear reactor. The release mechanism is designed to have a large excess holding force and a rapid, uniform, and dependable release. The fast release is accomplished by providing the electromagnet with slotttd polts separated by an insulating potting resin, and by constructing the poles with a ferro-nickel alloy. The combination of these two features materially reduces the eddy current power density whenever the magnetic field changes during a release operation. In addition to these features, the design of the armature is such as to provide ready entrance of fluid into any void that might tend to form during release of the armature. This also improves the release time for the mechanism. The large holding force for the mechanism is accomplished by providing a small, selected, uniform air gap between the inner pole piece and the armature.
Mechanical plasticity of cells
Bonakdar, Navid; Gerum, Richard; Kuhn, Michael; Spörrer, Marina; Lippert, Anna; Schneider, Werner; Aifantis, Katerina E.; Fabry, Ben
2016-10-01
Under mechanical loading, most living cells show a viscoelastic deformation that follows a power law in time. After removal of the mechanical load, the cell shape recovers only incompletely to its original undeformed configuration. Here, we show that incomplete shape recovery is due to an additive plastic deformation that displays the same power-law dynamics as the fully reversible viscoelastic deformation response. Moreover, the plastic deformation is a constant fraction of the total cell deformation and originates from bond ruptures within the cytoskeleton. A simple extension of the prevailing viscoelastic power-law response theory with a plastic element correctly predicts the cell behaviour under cyclic loading. Our findings show that plastic energy dissipation during cell deformation is tightly linked to elastic cytoskeletal stresses, which suggests the existence of an adaptive mechanism that protects the cell against mechanical damage.
Testa, Massimo
2015-01-01
Based on the fundamental principles of Relativistic Quantum Mechanics, we give a rigorous, but completely elementary, proof of the relation between fundamental observables of a statistical system when measured relatively to two inertial reference frames, connected by a Lorentz transformation.
Playing at Statistical Mechanics
Clark, Paul M.; And Others
1974-01-01
Discussed are the applications of counting techniques of a sorting game to distributions and concepts in statistical mechanics. Included are the following distributions: Fermi-Dirac, Bose-Einstein, and most probable. (RH)
Federal Laboratory Consortium — NETL’s Mechanical Testing Laboratory in Albany, OR, helps researchers investigate materials that can withstand the heat and pressure commonly found in fossil energy...
Molecular Mechanisms of Preeclampsia
N. Vitoratos; D. Hassiakos; Iavazzo, C.
2012-01-01
Preeclampsia is one of the leading causes of maternal morbidity/mortality. The pathogenesis of preeclampsia is still under investigation. The aim of this paper is to present the molecular mechanisms implicating in the pathway leading to preeclampsia.
Mechanical Enterogenesis - A Review
Directory of Open Access Journals (Sweden)
Rebecca Stark
2012-01-01
Full Text Available Mechanical enterogenesis is a novel method of lengthening pre-existing intestine with distractive force. The application of mechanical force on small intestine aims to induce cellular proliferation and ultimately increase bowel length. This has been investigated primarily for the treatment of short bowel syndrome (SBS. Research has been ongoing for well over a decade in this arena and a multitude of advances have been made, both in the understanding of the biology behind force induced cellular proliferation and in the basic mechanics of force delivery systems. Important experimental models have been developed for studying this phenomenon and the collaboration of engineers and medical researchers has lead to the design of several devices that successfully lengthen small intestine. This has catapulted the field forward and there may soon be a device suitable for medical use in humans. This review analyses the past, present and future of mechanical enterogenesis.
Computational Continuum Mechanics
Shabana, Ahmed A
2011-01-01
This text presents the theory of continuum mechanics using computational methods. Ideal for students and researchers, the second edition features a new chapter on computational geometry and finite element analysis.
Bower, Allan F
2009-01-01
Modern computer simulations make stress analysis easy. As they continue to replace classical mathematical methods of analysis, these software programs require users to have a solid understanding of the fundamental principles on which they are based. Develop Intuitive Ability to Identify and Avoid Physically Meaningless Predictions Applied Mechanics of Solids is a powerful tool for understanding how to take advantage of these revolutionary computer advances in the field of solid mechanics. Beginning with a description of the physical and mathematical laws that govern deformation in solids, the text presents modern constitutive equations, as well as analytical and computational methods of stress analysis and fracture mechanics. It also addresses the nonlinear theory of deformable rods, membranes, plates, and shells, and solutions to important boundary and initial value problems in solid mechanics. The author uses the step-by-step manner of a blackboard lecture to explain problem solving methods, often providing...
Statistical mechanics of superconductivity
Kita, Takafumi
2015-01-01
This book provides a theoretical, step-by-step comprehensive explanation of superconductivity for undergraduate and graduate students who have completed elementary courses on thermodynamics and quantum mechanics. To this end, it adopts the unique approach of starting with the statistical mechanics of quantum ideal gases and successively adding and clarifying elements and techniques indispensible for understanding it. They include the spin-statistics theorem, second quantization, density matrices, the Bloch–De Dominicis theorem, the variational principle in statistical mechanics, attractive interaction, and bound states. Ample examples of their usage are also provided in terms of topics from advanced statistical mechanics such as two-particle correlations of quantum ideal gases, derivation of the Hartree–Fock equations, and Landau’s Fermi-liquid theory, among others. With these preliminaries, the fundamental mean-field equations of superconductivity are derived with maximum mathematical clarity based on ...
Greiner, Walter
1989-01-01
"Quantum Dynamics" is a major survey of quantum theory based on Walter Greiner's long-running and highly successful courses at the University of Frankfurt. The key to understanding in quantum theory is to reinforce lecture attendance and textual study by working through plenty of representative and detailed examples. Firm belief in this principle led Greiner to develop his unique course and to transform it into a remarkable and comprehensive text. The text features a large number of examples and exercises involving many of the most advanced topics in quantum theory. These examples give practical and precise demonstrations of how to use the often subtle mathematics behind quantum theory. The text is divided into five volumes: Quantum Mechanics I - An Introduction, Quantum Mechanics II - Symmetries, Relativistic Quantum Mechanics, Quantum Electrodynamics, Gauge Theory of Weak Interactions. These five volumes take the reader from the fundamental postulates of quantum mechanics up to the latest research in partic...
Demtröder, Wolfgang
2017-01-01
This introduction to classical mechanics and thermodynamics provides an accessible and clear treatment of the fundamentals. Starting with particle mechanics and an early introduction to special relativity this textbooks enables the reader to understand the basics in mechanics. The text is written from the experimental physics point of view, giving numerous real life examples and applications of classical mechanics in technology. This highly motivating presentation deepens the knowledge in a very accessible way. The second part of the text gives a concise introduction to rotational motion, an expansion to rigid bodies, fluids and gases. Finally, an extensive chapter on thermodynamics and a short introduction to nonlinear dynamics with some instructive examples intensify the knowledge of more advanced topics. Numerous problems with detailed solutions are perfect for self study.
Mechanical properties of viruses.
de Pablo, Pedro J; Mateu, Mauricio G
2013-01-01
Structural biology techniques have greatly contributed to unveil the relationships between structure, properties and functions of viruses. In recent years, classic structural approaches are being complemented by single-molecule techniques such as atomic force microscopy and optical tweezers to study physical properties and functions of viral particles that are not accessible to classic structural techniques. Among these features are mechanical properties such as stiffness, intrinsic elasticity, tensile strength and material fatigue. The field of virus mechanics is contributing to materials science by investigating some physical parameters of "soft" biological matter and biological nano-objects. Virus mechanics studies are also starting to unveil the biological implications of physical properties of viruses. Growing evidence indicate that viruses are subjected to internal and external forces, and that they may have adapted to withstand and even use those forces. This chapter describes what is known on the mechanical properties of virus particles, their structural determinants, and possible biological implications, of which several examples are provided.
Classical mechanics without determinism
Nikolic, H.
2005-01-01
Classical statistical particle mechanics in the configuration space can be represented by a nonlinear Schrodinger equation. Even without assuming the existence of deterministic particle trajectories, the resulting quantum-like statistical interpretation is sufficient to predict all measurable results of classical mechanics. In the classical case, the wave function that satisfies a linear equation is positive, which is the main source of the fundamental difference between classical and quantum...
Odake, Satoru; Sasaki, Ryu
2011-01-01
A comprehensive review of the discrete quantum mechanics with the pure imaginary shifts and the real shifts is presented in parallel with the corresponding results in the ordinary quantum mechanics. The main subjects to be covered are the factorised Hamiltonians, the general structure of the solution spaces of the Schroedinger equation (Crum's theorem and its modification), the shape invariance, the exact solvability in the Schroedinger picture as well as in the Heisenberg picture, the creati...
Gol'dman, I I
2010-01-01
A comprehensive collection of problems of varying degrees of difficulty in nonrelativistic quantum mechanics, with answers and completely worked-out solutions. Among the topics: one-dimensional motion, transmission through a potential barrier, commutation relations, angular momentum and spin, and motion of a particle in a magnetic field. An ideal adjunct to any textbook in quantum mechanics, useful in courses in atomic and nuclear physics, mathematical methods in physics, quantum statistics and applied differential equations. 1961 edition.
Advanced Mechanics of Piezoelectricity
Qin, Qing-Hua
2013-01-01
"Advanced Mechanics of Piezoelectricity" presents a comprehensive treatment of piezoelectric materials using linear electroelastic theory, symplectic models, and Hamiltonian systems. It summarizes the current state of practice and presents the most recent research findings in piezoelectricity. It is intended for researchers and graduate students in the fields of applied mechanics, material science and engineering, computational engineering, and aerospace engineering. Dr. Qinghua Qin is a professor at the School of Engineering, Australian National University, Australia.
DEFF Research Database (Denmark)
Allin, Kristine H.; Nielsen, Trine; Pedersen, Oluf.
2015-01-01
Perturbations of the composition and function of the gut microbiota have been associated with metabolic disorders including obesity, insulin resistance and type 2 diabetes. Studies on mice have demonstrated several underlying mechanisms including host signalling through bacterial lipopolysacchari......Perturbations of the composition and function of the gut microbiota have been associated with metabolic disorders including obesity, insulin resistance and type 2 diabetes. Studies on mice have demonstrated several underlying mechanisms including host signalling through bacterial...
Institute of Scientific and Technical Information of China (English)
WANG; Hao; (王; 昊); PENG; Xiaofeng; (彭晓峰); WANG; Buxuan; (王补宣); LEE; Duzhong; (李笃中)
2003-01-01
A series of subcooled boiling experiments was conducted on very small platinum wires having diameters of 0.1 and 0.025 mm. Vapor bubbles were visually observed to sweep back and forth along the wires in the experiments. The dynamic characteristics of bubble-sweeping phenomenon are described, and the induced bubble interaction and nonlinear growth are investigated to understand the boiling heat transfer mechanisms. An unsymmetrical temperature model is proposed to explain the physical mechanism.
Mechanical Service; Service Mechanique
Energy Technology Data Exchange (ETDEWEB)
Alliaume, T.; Benoit, A.; Bonin, H.; Ducimetiere, D.; Essertaize, D.; Gelin, G.; Guillot, G.; Lemoine, C.; Mabo, J.C.; Mounier, F.; Tissot, S.; Verdier, G. [Inst. de Physique Nucleaire, Lyon-1 Univ., 69 - Villeurbanne (France)
1998-12-31
The service studies the mechanical part of the experiment or detectors used by the physics groups in collaboration with the physicists, engineers and the technicians of the experiment assistance group as well as with other technical groups. The mechanical service was implied in the following projects: CMS, VIRGO (the IGISOL ion guide chamber), PIAFE, NA50 (reaction chamber, metallic cluster source), ORION, SICANE, EDELWEISS II 2 figs.
Mechanisms for chromosome segregation.
Bouet, Jean-Yves; Stouf, Mathieu; Lebailly, Elise; Cornet, François
2014-12-01
Bacteria face the problem of segregating their gigantic chromosomes without a segregation period restricted in time and space, as Eukaryotes do. Segregation thus involves multiple activities, general or specific of a chromosome region and differentially controlled. Recent advances show that these various mechanisms conform to a “pair and release” rule, which appears as a general rule in DNA segregation. We describe the latest advances in segregation of bacterial chromosomes with emphasis on the different pair and release mechanisms.
Elementary Nonrelativistic Quantum Mechanics
Rosu, H C
2000-01-01
This is a graduate course on elementary quantum mechanics written for the benefit of undergraduate and graduate students. It is the English version of physics/0003106, which I did at the suggestion of several students from different countries. The topics included refer to the postulates of quantum mechanics, one-dimensional barriers and wells, angular momentum and spin, WKB method, harmonic oscillator, hydrogen atom, quantum scattering, and partial waves
Mechanical Engineering for Electronics.
Was, Loïc
2012-01-01
Schlumberger drilling tools are exposed to very hard loading conditions (shocks, vibrations, thermal cycling) while performing a job. As these tools are full of electronics, issues can quickly come from electronics failure. Mechanisms of failure occurring in electronics are very complex but can be predicted in some cases. The first part of the thesis describes in which context mechanical engineering applied to electronics is used in Schlumberger. The different kinds of failure which will be i...
Phase Field Fracture Mechanics.
Energy Technology Data Exchange (ETDEWEB)
Robertson, Brett Anthony [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-11-01
For this assignment, a newer technique of fracture mechanics using a phase field approach, will be examined and compared with experimental data for a bend test and a tension test. The software being used is Sierra Solid Mechanics, an implicit/explicit finite element code developed at Sandia National Labs in Albuquerque, New Mexico. The bend test experimental data was also obtained at Sandia Labs while the tension test data was found in a report online from Purdue University.
Holography and Quantum Mechanics
Wang, X J
2002-01-01
It is illustrated that quantum mechanics can be interpreted as holographic projection of higher dimension classical gravity. In this explanation every quantum path in D-dimension is dual to a classical path of (D+1)-dimension gravity under definite holographic projection. I consider 2-dimension non-relativitic free particle and harmonic oscillator as two examples, and find their gravity dual. I conjecture that every quantum mechanics system has their dual gravity description.
Ross, Donald
1976-01-01
Mechanics of Underwater Noise elucidates the basic mechanisms by which noise is generated, transmitted by structures and radiated into the sea. Organized into 10 chapters, this book begins with a description of noise, decibels and levels, significance of spectra, and passive sonar equation. Subsequent chapters discuss sound waves in liquids; acoustic radiation fundamentals; wind-generated ocean ambient noise; vibration isolation and structural damping; and radiation by plate flexural vibrations. Other chapters address cavitation, propeller cavitation noise, radiation by fluctuating-force (dipo
Painful neuropathy: Mechanisms.
Lee-Kubli, Corinne A; Calcutt, Nigel A
2014-01-01
Painful neuropathy, like the other complications of diabetes, is a growing healthcare concern. Unfortunately, current treatments are of variable efficacy and do not target underlying pathogenic mechanisms, in part because these mechanisms are not well defined. Rat and mouse models of type 1 diabetes are frequently used to study diabetic neuropathy, with rats in particular being consistently reported to show allodynia and hyperalgesia. Models of type 2 diabetes are being used with increasing frequency, but the current literature on the progression of indices of neuropathic pain is variable and relatively few therapeutics have yet been developed in these models. While evidence for spontaneous pain in rodent models is sparse, measures of evoked mechanical, thermal and chemical pain can provide insight into the pathogenesis of the condition. The stocking and glove distribution of pain tantalizingly suggests that the generator site of neuropathic pain is found within the peripheral nervous system. However, emerging evidence demonstrates that amplification in the spinal cord, via spinal disinhibition and neuroinflammation, and also in the brain, via enhanced thalamic activity or decreased cortical inhibition, likely contribute to the pathogenesis of painful diabetic neuropathy. Several potential therapeutic strategies have emerged from preclinical studies, including prophylactic treatments that intervene against underlying mechanisms of disease, treatments that prevent gains of nociceptive function, treatments that suppress enhancements of nociceptive function, and treatments that impede normal nociceptive mechanisms. Ongoing challenges include unraveling the complexity of underlying pathogenic mechanisms, addressing the potential disconnect between the perceived location of pain and the actual pain generator and amplifier sites, and finding ways to identify which mechanisms operate in specific patients to allow rational and individualized choice of targeted therapies.
Bruhns, Otto T
2003-01-01
Mechanics, and in particular, the mechanics of solids, forms the basis of all engi neering sciences. It provides the essential foundations for understanding the action of forces on bodies, and the effects of these forces on the straining of the body on the one hand, and on the deformation and motion of the body on the other. Thus, it provides the solutions of many problems with which the would-be engineer is going to be confronted with on a daily basis. In addition, in engineering studies, mechanics has a more vital importance, which many students appreciate only much later. Because of its clear, and analyt ical setup, it aids the student to a great extent in acquiring the necessary degree of abstraction ability, and logical thinking, skills without which no engineer in the practice today would succeed. Many graduates have confirmed to me that learning mechanics is generally per ceived as difficult. On the other hand, they always also declared that the preoccu pation with mechanics made an essential c...
Huang, Zhen; Ding, Huafeng
2013-01-01
This book contains mechanism analysis and synthesis. In mechanism analysis, a mobility methodology is first systematically presented. This methodology, based on the author's screw theory, proposed in 1997, of which the generality and validity was only proved recently, is a very complex issue, researched by various scientists over the last 150 years. The principle of kinematic influence coefficient and its latest developments are described. This principle is suitable for kinematic analysis of various 6-DOF and lower-mobility parallel manipulators. The singularities are classified by a new point of view, and progress in position-singularity and orientation-singularity is stated. In addition, the concept of over-determinate input is proposed and a new method of force analysis based on screw theory is presented. In mechanism synthesis, the synthesis for spatial parallel mechanisms is discussed, and the synthesis method of difficult 4-DOF and 5-DOF symmetric mechanisms, which was first put forward by the a...
Directory of Open Access Journals (Sweden)
Roman B. Golovkin
2015-12-01
Full Text Available Objective to establish the essential properties of the mechanism of charitable activities and to formulate the concept of quotmechanism of charitable activityquot. Methods the objective of the study is achieved using the complex of methods which are based on the interaction of dialectical and metaphysical analysis the epistemological properties of which allowed to reveal various aspects of the charitable activities mechanism functioning taking into account the principles of comprehensiveness complexity specificity and objectivity of the research. Results the rules are stated of using the term quotmechanismquot to characterize actions of state and law the essence of the charity mechanism is defined the definition of quotthe mechanism of charitable activity quot is formulated. Scientific novelty for the first time at theoretical level in legal science the definition of quotthe mechanism of charitable activityquot is formulated and its essential properties are set. Practical significance the research will contribute to improving the legal regulation in the field of philanthropy as well as to improving the efficiency and quality of charitable activity in the Russian Federation. nbsp
Wallace, John; Newman, Mike; Gutierrez, Homero; Hoffman, Charlie; Quakenbush, Tim; Waldeck, Dan; Leone, Christopher; Ostaszewski, Miro
2014-10-01
Ball Aerospace & Technologies Corp. developed a Resonant Scanning Mechanism (RSM) capable of combining a 250- Hz resonant scan about one axis with a two-hertz triangular scan about the orthogonal axis. The RSM enables a rapid, high-density scan over a significant field of regard (FOR) while minimizing size, weight, and power requirements. The azimuth scan axis is bearing mounted allowing for 30° of mechanical travel, while the resonant elevation axis is flexure and spring mounted with five degrees of mechanical travel. Pointing-knowledge error during quiescent static pointing at room temperature across the full range is better than 100 μrad RMS per axis. The compact design of the RSM, roughly the size of a soda can, makes it an ideal mechanism for use on low-altitude aircraft and unmanned aerial vehicles. Unique aspects of the opto-mechanical design include i) resonant springs which allow for a high-frequency scan axis with low power consumption; and ii) an independent lower-frequency scan axis allowing for a wide FOR. The pointing control system operates each axis independently and employs i) a position loop for the azimuth axis; and ii) a unique combination of parallel frequency and amplitude control loops for the elevation axis. All control and pointing algorithms are hosted on a 200-MHz microcontroller with 516 KB of RAM on a compact 3"×4" digital controller, also of Ball design.
Conventional mechanical ventilation
Directory of Open Access Journals (Sweden)
Tobias Joseph
2010-01-01
Full Text Available The provision of mechanical ventilation for the support of infants and children with respiratory failure or insufficiency is one of the most common techniques that are performed in the Pediatric Intensive Care Unit (PICU. Despite its widespread application in the PICUs of the 21st century, before the 1930s, respiratory failure was uniformly fatal due to the lack of equipment and techniques for airway management and ventilatory support. The operating rooms of the 1950s and 1960s provided the arena for the development of the manual skills and the refinement of the equipment needed for airway management, which subsequently led to the more widespread use of endotracheal intubation thereby ushering in the era of positive pressure ventilation. Although there seems to be an ever increasing complexity in the techniques of mechanical ventilation, its successful use in the PICU should be guided by the basic principles of gas exchange and the physiology of respiratory function. With an understanding of these key concepts and the use of basic concepts of mechanical ventilation, this technique can be successfully applied in both the PICU and the operating room. This article reviews the basic physiology of gas exchange, principles of pulmonary physiology, and the concepts of mechanical ventilation to provide an overview of the knowledge required for the provision of conventional mechanical ventilation in various clinical arenas.
Epigenetics: Biology's Quantum Mechanics
Directory of Open Access Journals (Sweden)
Richard A Jorgensen
2011-04-01
Full Text Available The perspective presented here is that modern genetics is at a similar stage of development as were early formulations of quantum mechanics theory in the 1920's and that in 2010 we are at the dawn of a new revolution in genetics that promises to enrich and deepen our understanding of the gene and the genome. The interrelationships and interdependence of two views of the gene - the molecular biological view and the epigenetic view - are explored, and it is argued that the classical molecular biological view is incomplete without incorporation of the epigenetic perspective and that in a sense the molecular biological view has been evolving to include the epigenetic view. Intriguingly, this evolution of the molecular view toward the broader and more inclusive epigenetic view of the gene has an intriguing, if not precise, parallel in the evolution of concepts of atomic physics from Newtonian mechanics to quantum mechanics that are interesting to consider.
Epigenetics: Biology's Quantum Mechanics.
Jorgensen, Richard A
2011-01-01
The perspective presented here is that modern genetics is at a similar stage of development as were early formulations of quantum mechanics theory in the 1920s and that in 2010 we are at the dawn of a new revolution in genetics that promises to enrich and deepen our understanding of the gene and the genome. The interrelationships and interdependence of two views of the gene - the molecular biological view and the epigenetic view - are explored, and it is argued that the classical molecular biological view is incomplete without incorporation of the epigenetic perspective and that in a sense the molecular biological view has been evolving to include the epigenetic view. Intriguingly, this evolution of the molecular view toward the broader and more inclusive epigenetic view of the gene has an intriguing, if not precise, parallel in the evolution of concepts of atomic physics from Newtonian mechanics to quantum mechanics that are interesting to consider.
Integrating function and mechanism.
McNamara, John M; Houston, Alasdair I
2009-12-01
Behavioural ecology often makes the assumption that animals can respond flexibly by adopting the optimal behaviour for each circumstance. However, as ethologists have long known, behaviour is determined by mechanisms that are not optimal in every circumstance. As we discuss here, we believe that it is necessary to integrate these separate traditions by considering the evolution of mechanisms, an approach referred to as 'Evo-mecho'. This integration is timely because there is a growing awareness of the importance of environmental complexity in shaping behaviour; there are established and effective computational procedures for simulating evolution and there is rapidly increasing knowledge of the neuronal basis of decision-making. Although behavioural ecologists have built complex models of optimal behaviour in simple environments, we argue that they need to focus on simple mechanisms that perform well in complex environments.
DEFF Research Database (Denmark)
van Gelderen, Laurens; Malmquist, L.M.V.; Jomaas, Grunde
2015-01-01
In order to improve predictions for the burning efficiency and the residue composition of in-situ burning of crude oil, the burning mechanism of crude oil was studied in relation to the composition of its hydrocarbon mixture, before, during and after the burning. The surface temperature, flame...... to the predictions of four conceptual models that describe the burning mechanism of multicomponent fuels. Based on the comparisons, hydrocarbon liquids were found to be best described by the Equilibrium Flash Vaporization model, showing a constant gas composition and gasification rate. The multicomponent fuels...... followed the diffusion-limited gasification model, showing a change in the hydrocarbon composition of the fuel and its evaporating gases, as well as a decreasing gasification rate, as the burning progressed. This burning mechanism implies that the residue composition and burning efficiency mainly depend...
DEFF Research Database (Denmark)
Sonne, David P; Hansen, Morten; Knop, Filip K
2014-01-01
Bile acid sequestrants have been used for decades for the treatment of hypercholesterolaemia. Sequestering of bile acids in the intestinal lumen interrupts enterohepatic recirculation of bile acids, which initiate feedback mechanisms on the conversion of cholesterol into bile acids in the liver......, thereby lowering cholesterol concentrations in the circulation. In the early 1990s, it was observed that bile acid sequestrants improved glycaemic control in patients with type 2 diabetes. Subsequently, several studies confirmed the finding and recently - despite elusive mechanisms of action - bile acid...... of bile acid sequestrants in the treatment of type 2 diabetes, the possible mechanism of action and the role of bile acid-induced secretion of GLP1 via activation of TGR5....
Fundamentals of quantum mechanics
House, J E
2017-01-01
Fundamentals of Quantum Mechanics, Third Edition is a clear and detailed introduction to quantum mechanics and its applications in chemistry and physics. All required math is clearly explained, including intermediate steps in derivations, and concise review of the math is included in the text at appropriate points. Most of the elementary quantum mechanical models-including particles in boxes, rigid rotor, harmonic oscillator, barrier penetration, hydrogen atom-are clearly and completely presented. Applications of these models to selected “real world” topics are also included. This new edition includes many new topics such as band theory and heat capacity of solids, spectroscopy of molecules and complexes (including applications to ligand field theory), and small molecules of astrophysical interest.
Arraut, Ivan
2015-01-01
The Higgs mechanism at the graviton level formulated as a Vainshtein mechanism in time domains implies that the extra-degrees of freedom become relevant depending on the direction of time (frame of reference) with respect to the preferred time direction (preferred frame) defined by the St\\"uckelberg function $T_0(r,t)$ which contains the information of the extra-degrees of freedom of the theory. In this manuscript, I make the general definition of the Higgs mechanism by analyzing the gauge symmetries of the action and the general form of the vacuum solutions for the graviton field. In general, the symmetry generators depending explicitly on the St\\"uckelberg fields are broken at the vacuum level. These broken generators, define the number of Nambu-Goldstone bosons which will be eating up by the dynamical metric in order to become massive.
Stochastic Neutrino Mixing Mechanism
Guzzo, M M; Peres, O L G; Zavanin, E M
2013-01-01
We propose a mechanism which provides an explanation of the Gallium and antineutrino reactor anomalies. Differently from original Pontecorvo's hypothesis, this mechanism is based on the phenomenological assumption in which the admixture of neutrino mass eigenstates in the moments of neutrino creation and detection can assume different configurations around the admixture parametrized by the usual values of the mixing angles $\\theta_{12}$, $\\theta_{23}$ and $\\theta_{13}$. For simplicity, we assume a Gaussian distribution for the mixing angles in such a way that the average value of this distribution is given by the usual values of the mixing angles and the width of the Gaussian is denoted by $\\alpha$. We show that the proposed mechanism provides a possible explanation for very short-baseline neutrino disappearance, necessary to accommodate Gallium and antineutrino reactor anomalies, which is not allowed in usual neutrino oscillations based on Pontecorvo's original hypotheses. We also can describe high-energy os...
Arraut, Ivan
2015-09-01
The Higgs mechanism at the graviton level formulated as a Vainshtein mechanism in time domains implies that the extra-degrees of freedom become relevant depending on the direction of time (frame of reference) with respect to the preferred time direction (preferred frame) defined by the Stückelberg function T_0(r,t) which contains the information of the extra-degrees of freedom of the theory. In this manuscript, I make the general definition of the Higgs mechanism by analyzing the gauge symmetries of the action and the general form of the vacuum solutions for the graviton field. In general, the symmetry generators depending explicitly on the Stückelberg fields are broken at the vacuum level. These broken generators, define the number of Nambu-Goldstone bosons which will be eating up by the dynamical metric in order to become massive.
Molecular mechanisms of meditation.
Jindal, Vishal; Gupta, Sorab; Das, Ritwik
2013-12-01
Meditation is a complex process involving change in cognition, memory, and social and emotional control, and causes improvement in various cardiovascular, neurological, autoimmune, and renal pathologies. Meditation also become widely used in medical and psychological treatment therapies for stress-related physical and mental disorders. But still, biological mechanisms in terms of effect on brain and body are poorly understood. This paper explains the basic changes due to meditation in cerebral cortex, prefrontal area, cingulate gyrus, neurotransmitters, white matter, autonomic nervous system, limbic system, cytokines, endorphins, hormones, etc. The following is a review of the current literature regarding the various neurophysiological mechanisms, neuro-endocrine mechanisms, neurochemical substrates, etc. that underlies the complex processes of meditation.
Mechanical Biological Treatment
DEFF Research Database (Denmark)
Bilitewski, B-; Oros, Christiane; Christensen, Thomas Højlund
2011-01-01
or residual waste (after some recyclables removed at the source). The concept was originally to reduce the amount of waste going to landfill, but MBT technologies are today also seen as plants recovering fuel as well as material fractions. As the name suggests the technology combines mechanical treatment......The basic processes and technologies of composting and anaerobic digestion, as described in the previous chapters, are usually used for specific or source-separated organic waste flows. However, in the 1990s mechanical biological waste treatment technologies (MBT) were developed for unsorted...... technologies (screens, sieves, magnets, etc.) with biological technologies (composting, anaerobic digestion). Two main technologies are available: Mechanical biological pretreatment (MBP), which first removes an RDF fraction and then biologically treats the remaining waste before most of it is landfilled...
Fracture Mechanics of Concrete
DEFF Research Database (Denmark)
Ulfkjær, Jens Peder
Chapter 1 Chapter l contains the introduction to this thesis. The scope of the thesis is partly to investigate different numerical and analytical models based on fracture mechanical ideas, which are able to predict size effects, and partly to perform an experimental investigation on high-strength......Chapter 1 Chapter l contains the introduction to this thesis. The scope of the thesis is partly to investigate different numerical and analytical models based on fracture mechanical ideas, which are able to predict size effects, and partly to perform an experimental investigation on high......-strength concrete. Chapter 2 A description of the factors which influence the strength and cracking of concrete and high strength concrete is made. Then basic linear fracture mechanics is outlined followed by a description and evaluation of the models used to describe concrete fracture in tension. The chapter ends...
Mechanical engineer's reference book
Parrish, A
1973-01-01
Mechanical Engineer's Reference Book: 11th Edition presents a comprehensive examination of the use of Systéme International d' Unités (SI) metrication. It discusses the effectiveness of such a system when used in the field of engineering. It addresses the basic concepts involved in thermodynamics and heat transfer. Some of the topics covered in the book are the metallurgy of iron and steel; screw threads and fasteners; hole basis and shaft basis fits; an introduction to geometrical tolerancing; mechanical working of steel; high strength alloy steels; advantages of making components as castings
Kogan, VI; Gersch, Harold
2011-01-01
Written by a pair of distinguished Soviet mathematicians, this compilation presents 160 lucidly expressed problems in nonrelativistic quantum mechanics plus completely worked-out solutions. Some were drawn from the authors' courses at the Moscow Institute of Engineering, but most were prepared especially for this book. A high-level supplement rather than a primary text, it constitutes a masterful complement to advanced undergraduate and graduate texts and courses in quantum mechanics.The mathematics employed in the proofs of the problems-asymptotic expansions of functions, Green's functions, u
Fundamentals of continuum mechanics
Rudnicki, John W
2014-01-01
A concise introductory course text on continuum mechanics Fundamentals of Continuum Mechanics focuses on the fundamentals of the subject and provides the background for formulation of numerical methods for large deformations and a wide range of material behaviours. It aims to provide the foundations for further study, not just of these subjects, but also the formulations for much more complex material behaviour and their implementation computationally. This book is divided into 5 parts, covering mathematical preliminaries, stress, motion and deformation, balance of mass, momentum and energ
Classical mechanics with Maxima
Timberlake, Todd Keene
2016-01-01
This book guides undergraduate students in the use of Maxima—a computer algebra system—in solving problems in classical mechanics. It functions well as a supplement to a typical classical mechanics textbook. When it comes to problems that are too difficult to solve by hand, computer algebra systems that can perform symbolic mathematical manipulations are a valuable tool. Maxima is particularly attractive in that it is open-source, multiple-platform software that students can download and install free of charge. Lessons learned and capabilities developed using Maxima are easily transferred to other, proprietary software.
DEFF Research Database (Denmark)
Hansen, John Michael
1999-01-01
These notes describe an automated procedure for analysis and synthesis of mechanisms. The analysis method is based on the body coordinate formulation, and the synthesis is based on applying optimization methods, used to minimize the difference between an actual and a desired behaviour......These notes describe an automated procedure for analysis and synthesis of mechanisms. The analysis method is based on the body coordinate formulation, and the synthesis is based on applying optimization methods, used to minimize the difference between an actual and a desired behaviour...
Saxon, David S
2012-01-01
Based on lectures for an undergraduate UCLA course in quantum mechanics, this volume focuses on the formulas of quantum mechanics rather than applications. Widely used in both upper-level undergraduate and graduate courses, it offers a broad self-contained survey rather than in-depth treatments.Topics include the dual nature of matter and radiation, state functions and their interpretation, linear momentum, the motion of a free particle, Schrödinger's equation, approximation methods, angular momentum, and many other subjects. In the interests of keeping the mathematics as simple as possible, m
Introduction to continuum mechanics
Lai, W Michael; Rubin, David
1996-01-01
Introduction to Continuum Mechanics is a recently updated and revised text which is perfect for either introductory courses in an undergraduate engineering curriculum or for a beginning graduate course.Continuum Mechanics studies the response of materials to different loading conditions. The concept of tensors is introduced through the idea of linear transformation in a self-contained chapter, and the interrelation of direct notation, indicial notation, and matrix operations is clearly presented. A wide range of idealized materials are considered through simple static and dynamic problems, a
Yamane, Takashi
2016-01-01
This book first describes medical devices in relation to regenerative medicine before turning to a more specific topic: artificial heart technologies. Not only the pump mechanisms but also the bearing, motor mechanisms, and materials are described, including expert information. Design methods are described to enhance hemocompatibility: main concerns are reduction of blood cell damage and protein break, as well as prevention of blood clotting. Regulatory science from R&D to clinical trials is also discussed to verify the safety and efficacy of the devices.
Corinaldesi, Ernesto
1963-01-01
Geared toward advanced undergraduate and graduate students of physics, this text provides readers with a background in relativistic wave mechanics and prepares them for the study of field theory. The treatment originated as a series of lectures from a course on advanced quantum mechanics that has been further amplified by student contributions.An introductory section related to particles and wave functions precedes the three-part treatment. An examination of particles of spin zero follows, addressing wave equation, Lagrangian formalism, physical quantities as mean values, translation and rotat
Basniev, Kaplan S; Chilingar, George V 0
2012-01-01
The mechanics of fluid flow is a fundamental engineering discipline explaining both natural phenomena and human-induced processes, and a thorough understanding of it is central to the operations of the oil and gas industry. This book, written by some of the world's best-known and respected petroleum engineers, covers the concepts, theories, and applications of the mechanics of fluid flow for the veteran engineer working in the field and the student, alike. It is a must-have for any engineer working in the oil and gas industry.
Computational statistical mechanics
Hoover, WG
1991-01-01
Computational Statistical Mechanics describes the use of fast computers to simulate the equilibrium and nonequilibrium properties of gases, liquids, and solids at, and away from equilibrium. The underlying theory is developed from basic principles and illustrated by applying it to the simplest possible examples. Thermodynamics, based on the ideal gas thermometer, is related to Gibb's statistical mechanics through the use of Nosé-Hoover heat reservoirs. These reservoirs use integral feedback to control temperature. The same approach is carried through to the simulation and anal
Problems in classical mechanics
Katkar, L N
2014-01-01
Problems in classical mechanics presents a lucid treatment of the formulations of Lagrangian, Hamiltonian, and the Principles of Calculus of Variations etc. important for the study of modern physics. The study of classical mechanics prepares students to apply the principles and the mathematical tools to solve real life problems. The book also incorporates and discusses in detail topics such as Central Force Motion, Rigid Body Motion and Canonical Transformations. KEY FEATURES: Around 200 solved examples with complete mathematical theory Around 70 examples given as an exercise to test and develop students understanding The physical interpretation of the Hamiltonian is highlighted
Dynamically assisted Schwinger mechanism.
Schützhold, Ralf; Gies, Holger; Dunne, Gerald
2008-09-26
We study electron-positron pair creation from the Dirac vacuum induced by a strong and slowly varying electric field (Schwinger effect) which is superimposed by a weak and rapidly changing electromagnetic field (dynamical pair creation). In the subcritical regime where both mechanisms separately are strongly suppressed, their combined impact yields a pair creation rate which is dramatically enhanced. Intuitively speaking, the strong electric field lowers the threshold for dynamical particle creation--or, alternatively, the fast electromagnetic field generates additional seeds for the Schwinger mechanism. These findings could be relevant for planned ultrahigh intensity lasers.
Probabilistic approach to mechanisms
Sandler, BZ
1984-01-01
This book discusses the application of probabilistics to the investigation of mechanical systems. The book shows, for example, how random function theory can be applied directly to the investigation of random processes in the deflection of cam profiles, pitch or gear teeth, pressure in pipes, etc. The author also deals with some other technical applications of probabilistic theory, including, amongst others, those relating to pneumatic and hydraulic mechanisms and roller bearings. Many of the aspects are illustrated by examples of applications of the techniques under discussion.
Rosu, H C
2000-01-01
This is the first graduate course on elementary quantum mechanics in Internet written in Romanian for the benefit of Romanian speaking students (Romania and Moldova). It is a translation (with corrections) of the Spanish version of the course (physics/9808031, English translation is under consideration), which I did at the request of students of physics in Bucharest. The topics included refer to the postulates of quantum mechanics, one-dimensional barriers and wells, angular momentum and spin, WKB method, harmonic oscillator, hydrogen atom, quantum scattering, and partial waves
Vortex mechanism in hydrocyclones
Institute of Scientific and Technical Information of China (English)
徐继润; 刘正宁; 邢军; 李新跃; 黄慧; 徐海燕; 罗茜
2001-01-01
On the basis of analyzing the vortex characteristics, a new mechanism of the vortex formation in hydrocyclones is developed. The main concept of the mechanism is that the vortex flow in a hydrocyclone is resulted from the overlapping of container rotation and hole leakage. The model is then used to explain the compound distribution of free vortex and forced vortex, predict the similarity of tangential velocity at different input pressures, and make count of the principle of small hydrocyclone with lower cut-size than large one. Meanwhile a new possible approach to a large hydro-cyclone with lower cut-size by minimizing or eliminating the air core is discussed briefly.
Volokh, Konstantin
2016-01-01
This book provides a concise introduction to soft matter modelling. It offers an up-to-date review of continuum mechanical description of soft and biological materials from the basics to the latest scientific materials. It includes multi-physics descriptions, such as chemo-, thermo-, electro- mechanical coupling. It derives from a graduate course at Technion that has been established in recent years. It presents original explanations for some standard materials and features elaborated examples on all topics throughout the text. PowerPoint lecture notes can be provided to instructors. .
Mechanical Parking System Logistics
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
As the number of motor vehicles increases rapidly in many populated countries, t he shortage of parking space has become a difficult problem to all cities around the world. The contradiction between the shortage of parking space and the incr easing number of motor vehicles is still growing in the recent years. The utiliz ation of various kinds of mechanical parking facilities is an effective solution to this problem. How to organize a reasonable logistics system in a mechanical parking lot so that as man...
Experimental unsaturated soil mechanics
Delage, Pierre
2008-01-01
In this general report, experimental systems and procedures of investigating the hydro-mechanical behaviour of unsaturated soils are presented. The water retention properties of unsaturated soils are commented and linked to various physical parameters and properties of the soils. Techniques of controlling suction are described together with their adaptation in various laboratory testing devices. Some typical features of the mechanical behaviour of unsaturated soils are presented within an elasto-plastic framework. An attempt to describe the numerous and significant recent advances in the investigation of the behaviour of unsaturated soils, including the contributions to this Conference, is proposed.
Quantum mechanics selected topics
Perelomov, Askold Mikhailovich
1998-01-01
It can serve as a good supplement to any quantum mechanics textbook, filling the gap between standard textbooks and higher-level books on the one hand and journal articles on the other. This book provides a detailed treatment of the scattering theory, multidimensional quasi-classical approximation, non-stationary problems for oscillators and the theory of unstable particles. It will be useful for postgraduate students and researchers who wish to find new, interesting information hidden in the depths of non-relativistic quantum mechanics.
Casscells, W; Engler, D; Willerson, J. T.
1994-01-01
Restenosis after percutaneous transluminal coronary angioplasty remains a problem, which suggests that we still do not fully understand its mechanisms. We review here the current understanding of the cell biology of restenosis, including clinical correlation (risk factors), randomized clinical trials, human histology, animal models, and in vitro studies.
Mechanical Measurements Laboratory
Maximilien Brice
2007-01-01
The CERN mechanical measurements team check the sensors on one of the ATLAS inner detector end-caps using high precision measurement equipment. Remote checks like this must be made on these sensitive detector components before they can be transported to make sure that all systems are working correctly.
Statistical mechanics of pluripotency.
MacArthur, Ben D; Lemischka, Ihor R
2013-08-01
Recent reports using single-cell profiling have indicated a remarkably dynamic view of pluripotent stem cell identity. Here, we argue that the pluripotent state is not well defined at the single-cell level but rather is a statistical property of stem cell populations, amenable to analysis using the tools of statistical mechanics and information theory.
Residential Mechanical Precooling
Energy Technology Data Exchange (ETDEWEB)
German, a. [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States); Hoeschele, M. [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States)
2014-12-01
This research conducted by the Alliance for Residential Building Innovation team evaluated mechanical air conditioner pre-cooling strategies in homes throughout the United States. EnergyPlus modeling evaluated two homes with different performance characteristics in seven climates. Results are applicable to new construction homes and most existing homes built in the last 10 years, as well as fairly efficient retrofitted homes.
Marine Corps Inst., Washington, DC.
This student guide, one of a series of correspondence training courses designed to improve the job performance of members of the Marine Corps, deals with the skills needed by air conditioning mechanics. Addressed in the four chapters, or lessons, of the manual are the following topics: principles of air conditioning, refrigeration components as…
DEFF Research Database (Denmark)
Jensen, Bror Skytte; Jensen, H.
1986-01-01
. The data for kaolinite were similarly interpreted as adsorption of hydroxylated complexes of the polyvalent cations, a mechanism which has previously been suggested for the adsorption of heavy metals onto muds, sludges and organic debris. In the case of kaolinite, indications of additional reactions like...
Abstractions for Mechanical Systems
DEFF Research Database (Denmark)
Sloth, Christoffer; Wisniewski, Rafael
2012-01-01
mechanical system. The tangential manifolds are generated using constants of motion, which can be derived from Noether's theorem. The transversal manifolds are subsequently generated on a reduced space, given by the Routhian, via action-angle coordinates. The method fully applies for integrable systems. We...
Structured Mechanical Collage.
Huang, Zhe; Wang, Jiang; Fu, Hongbo; Lau, Rynson W H
2014-07-01
We present a method to build 3D structured mechanical collages consisting of numerous elements from the database given artist-designed proxy models. The construction is guided by some graphic design principles, namely unity, variety and contrast. Our results are visually more pleasing than previous works as confirmed by a user study.
Guyton, J. W.
1972-01-01
An inexpensive, simple mechanical model of a fault can be produced to simulate the effects leading to an earthquake. This model has been used successfully with students from elementary to college levels and can be demonstrated to classes as large as thirty students. (DF)
Horticultural Mechanics Competencies
Shipley, W. Edward
1974-01-01
Ornamental horticulture teachers and managers of ornamental horticulture businesses were surveyed to determine which agricultural mechanics knowledges and skills are needed for entry-level employment in nursery, greenhouse, turf, and landscape management, which are common to the four areas, and the appropriate grade level at which they should be…
Principles of Mechanical Excavation
Energy Technology Data Exchange (ETDEWEB)
Lislerud, A. [Tamrock Corp., Tampere (Finland)
1997-12-01
Mechanical excavation of rock today includes several methods such as tunnel boring, raiseboring, roadheading and various continuous mining systems. Of these raiseboring is one potential technique for excavating shafts in the repository for spent nuclear fuel and dry blind boring is promising technique for excavation of deposition holes, as demonstrated in the Research Tunnel at Olkiluoto. In addition, there is potential for use of other mechanical excavation techniques in different parts of the repository. One of the main objectives of this study was to analyze the factors which affect the feasibility of mechanical rock excavation in hard rock conditions and to enhance the understanding of factors which affect rock cutting so as to provide an improved basis for excavator performance prediction modeling. The study included the following four main topics: (a) phenomenological model based on similarity analysis for roller disk cutting, (b) rock mass properties which affect rock cuttability and tool life, (c) principles for linear and field cutting tests and performance prediction modeling and (d) cutter head lacing design procedures and principles. As a conclusion of this study, a test rig was constructed, field tests were planned and started up. The results of the study can be used to improve the performance prediction models used to assess the feasibility of different mechanical excavation techniques at various repository investigation sites. (orig.). 21 refs.
Hesse, Constanze; Franz, Volker H.
2009-01-01
The availability of visual information influences the execution of goal-directed movements. This is very prominent in memory conditions, where a delay is introduced between stimulus presentation and execution of the movement. The corresponding effects could be due to a decay of the visual information or to different processing mechanisms used for…
Mechanical cleaning of graphene
Goossens, A.M.; Calado, V.E.; Barreiro, A.; Watanabe, K.; Taniguchi, T.; Vandersypen, L.M.K.
2012-01-01
Contamination of graphene due to residues from nanofabrication often introduces background doping and reduces electron mobility. For samples of high electronic quality, post-lithography cleaning treatments are therefore needed. We report that mechanical cleaning based on contact mode atomic force mi
Fuzziness in Quantum Mechanics
Granik, A
1996-01-01
It is shown that quantum mechanics can be regarded as what one might call a "fuzzy" mechanics whose underlying logic is the fuzzy one, in contradistinction to the classical "crisp" logic. Therefore classical mechanics can be viewed as a crisp limit of a "fuzzy" quantum mechanics. Based on these considerations it is possible to arrive at the Schroedinger equation directly from the Hamilton-Jacobi equation. The link between these equations is based on the fact that a unique ("crisp") trajectory of a classical particle emerges out of a continuum of possible paths collapsing to a single trajectory according to the principle of least action. This can be interpreted as a consequence of an assumption that a quantum "particle" "resides" in every path of the continuum of paths which collapse to a single(unique) trajectory of an observed classical motion. A wave function then is treated as a function describing a deterministic entity having a fuzzy character. As a consequence of such an interpretation, the complimentar...
Mechanisms of multidrug transporters
Bolhuis, H; van Veen, H.W.; Poolman, B.; Driessen, A.J.M.; Konings, W.N
1997-01-01
Drug resistance, mediated by various mechanisms, plays a crucial role in the failure of the drug-based treatment of various infectious diseases. As a result, these infectious diseases re-emerge rapidly and cause many victims every year. Another serious threat is imposed by the development of multidr
Flight Mechanics Symposium 1997
Walls, Donna M. (Editor)
1997-01-01
This conference publication includes papers and abstracts presented at the Flight Mechanics Symposium. This symposium featured technical papers on a wide range of issues related to orbit-attitude prediction, determination, and control; attitude sensor calibration; attitude determination error analysis; attitude dynamics; and orbit decay and maneuver strategy. Government, industry, and the academic community participated in the preparation and presentation of these papers.
Industrial Mechanical Maintenance.
Hendrix, Laborn J.
This manual was developed to assist teachers in Oklahoma in preparing students for industrial mechanical maintenance. The materials in this teacher's guide are organized in 14 units of instruction covering the following four areas: receiving and setting equipment; equipment hookup and operation; equipment layout, anchoring, and setup; and…
Mechanically Invisible Polymer Coatings
DEFF Research Database (Denmark)
2014-01-01
phase comprises particles, said particles comprising a filler material and an encapsulating coating of a second polymeric material, wherein the backbones of the first and second polymeric materials are the same. The composition may be used in electroactive polymers (EAPs) in order to obtain mechanically...... invisible polymer coatings....
Nonlinear tsunami generation mechanism
Directory of Open Access Journals (Sweden)
M. A. Nosov
2001-01-01
Full Text Available The nonlinear mechanism of long gravitational surface water wave generation by high-frequency bottom oscillations in a water layer of constant depth is investigated analytically. The connection between the surface wave amplitude and the parameters of bottom oscillations and source length is investigated.
Classical Mechanics Laboratory
Brosing, Juliet W.
2006-12-01
At Pacific University we have included a lab with our upper division Classical Mechanics class. We do a combination of physical labs (air resistance, harmonic motion, amusement park physics), Maple labs (software), and projects. Presentation of some of the labs, results and challenges with this course will be included.
Quantum Chaos and Statistical Mechanics
Srednicki, Mark
1994-01-01
We briefly review the well known connection between classical chaos and classical statistical mechanics, and the recently discovered connection between quantum chaos and quantum statistical mechanics.
Valenza, John J., II
Salt scaling is superficial damage caused by freezing a saline solution on the surface of a cementitious body. The damage consists of the removal of small chips or flakes of binder. The discovery of this phenomenon in the early 1950's prompted hundreds of experimental studies, which clearly elucidated the characteristics of this damage. In particular it was shown that a pessimum salt concentration exists, where a moderate salt concentration (˜3%) results in the most damage. Despite the numerous studies, the mechanism responsible for salt scaling has not been identified. In this work it is shown that salt scaling is a result of the large thermal expansion mismatch between ice and the cementitious body, and that the mechanism responsible for damage is analogous to glue-spalling. When ice forms on a cementitious body a bi-material composite is formed. The thermal expansion coefficient of the ice is ˜5 times that of the underlying body, so when the temperature of the composite is lowered below the melting point, the ice goes into tension. Once this stress exceeds the strength of the ice, cracks initiate in the ice and propagate into the surface of the cementitious body, removing a flake of material. The glue-spall mechanism accounts for all of the characteristics of salt scaling. In particular, a theoretical analysis is presented which shows that the pessimum concentration is a consequence of the effect of brine pockets on the mechanical properties of ice, and that the damage morphology is accounted for by fracture mechanics. Finally, empirical evidence is presented that proves that the glue-small mechanism is the primary cause of salt scaling. The primary experimental tool used in this study is a novel warping experiment, where a pool of liquid is formed on top of a thin (˜3 mm) plate of cement paste. Stresses in the plate, including thermal expansion mismatch, result in warping of the plate, which is easily detected. This technique revealed the existence of
Quantum Mechanics As A Limiting Case of Classical Mechanics
Ghose, Partha
2000-01-01
In spite of its popularity, it has not been possible to vindicate the conventional wisdom that classical mechanics is a limiting case of quantum mechanics. The purpose of the present paper is to offer an alternative point of view in which quantum mechanics emerges as a limiting case of classical mechanics in which the classical system is decoupled from its environment.
Pragmatic Mechanism of Homonym
Institute of Scientific and Technical Information of China (English)
马群英; 王亚辉
2014-01-01
Words, derivation of symbols, are a part played in human affairs by language of all kinds, and especially of their influ⁃ence on thought. According to The Triangle of Reference, words/symbols are endowed with references, some of which are one-on-one connected, and some of which are one-on-multiple colligated, modulated by social convention. Phenomena of using homonym are ubiquitous while the system of using it is still opaque. The multiple meaning of homonym is considered to have a pragmatic mechanism in which the implementing process of utterer and the construing pattern of hearer are regulated and formu⁃lated. This paper is tentatively cogitating polysemy in a system of pragmatic utility and tabling a pragmatic mechanism of hom⁃onym for better understanding and academic contribution of it.
Responding to Mechanical Antigravity
Millis, Marc G.; Thomas, Nicholas E.
2006-01-01
Based on the experiences of the NASA Breakthrough Propulsion Physics Project, suggestions are offered for constructively responding to proposals that purport breakthrough propulsion using mechanical devices. Because of the relatively large number of unsolicited submissions received (about 1 per workday) and because many of these involve similar concepts, this report is offered to help the would-be submitters make genuine progress as well as to help reviewers respond to such submissions. Devices that use oscillating masses or gyroscope falsely appear to create net thrust through differential friction or by misinterpreting torques as linear forces. To cover both the possibility of an errant claim and a genuine discovery, reviews should require that submitters meet minimal thresholds of proof before engaging in further correspondence; such as achieving sustained deflection of a level-platform pendulum in the case of mechanical thrusters.
Immunosuppressive mechanisms in glioblastoma.
Nduom, Edjah K; Weller, Michael; Heimberger, Amy B
2015-11-01
Despite maximal surgical and medical therapy, the treatment of glioblastoma remains a seriously vexing problem, with median survival well under 2 years and few long-term survivors. Targeted therapy has yet to produce significant advances in treatment of these lesions in spite of advanced molecular characterization of glioblastoma and glioblastoma cancer stem cells. Recently, immunotherapy has emerged as a promising mode for some of the hardest to treat tumors, including metastatic melanoma. Although immunotherapy has been evaluated in glioblastoma in the past with limited success, better understanding of the failures of these therapies could lead to more successful treatments in the future. Furthermore, there is a persistent challenge for the use of immune therapy to treat glioblastoma secondary to the existence of redundant mechanisms of tumor-mediated immune suppression. Here we will address these mechanisms of immunosuppression in glioblastoma and therapeutic approaches.
Hierarchical auxetic mechanical metamaterials.
Gatt, Ruben; Mizzi, Luke; Azzopardi, Joseph I; Azzopardi, Keith M; Attard, Daphne; Casha, Aaron; Briffa, Joseph; Grima, Joseph N
2015-02-11
Auxetic mechanical metamaterials are engineered systems that exhibit the unusual macroscopic property of a negative Poisson's ratio due to sub-unit structure rather than chemical composition. Although their unique behaviour makes them superior to conventional materials in many practical applications, they are limited in availability. Here, we propose a new class of hierarchical auxetics based on the rotating rigid units mechanism. These systems retain the enhanced properties from having a negative Poisson's ratio with the added benefits of being a hierarchical system. Using simulations on typical hierarchical multi-level rotating squares, we show that, through design, one can control the extent of auxeticity, degree of aperture and size of the different pores in the system. This makes the system more versatile than similar non-hierarchical ones, making them promising candidates for industrial and biomedical applications, such as stents and skin grafts.
Csanády, Etele
2013-01-01
Wood is one of the most valuable materials for mankind, and since our earliest days wood materials have been widely used. Today we have modern woodworking machine and tools; however, the raw wood materials available are continuously declining. Therefore we are forced to use this precious material more economically, reducing waste wherever possible. This new textbook on the “Mechanics of Wood Machining” combines the quantitative, mathematical analysis of the mechanisms of wood processing with practical recommendations and solutions. Bringing together materials from many sources, the book contains new theoretical and experimental approaches and offers a clear and systematic overview of the theory of wood cutting, thermal loading in wood-cutting tools, dynamic behaviour of tool and work piece, optimum choice of operational parameters and energy consumption, the wear process of the tools, and the general regularities of wood surface roughness. Diagrams are provided for the quick estimation of various process ...
Origami based Mechanical Metamaterials
Lv, Cheng; Krishnaraju, Deepakshyam; Konjevod, Goran; Yu, Hongyu; Jiang, Hanqing
2014-01-01
We describe mechanical metamaterials created by folding flat sheets in the tradition of origami, the art of paper folding, and study them in terms of their basic geometric and stiffness properties, as well as load bearing capability. A periodic Miura-ori pattern and a non-periodic Ron Resch pattern were studied. Unexceptional coexistence of positive and negative Poisson's ratio was reported for Miura-ori pattern, which are consistent with the interesting shear behavior and infinity bulk modulus of the same pattern. Unusually strong load bearing capability of the Ron Resch pattern was found and attributed to the unique way of folding. This work paves the way to the study of intriguing properties of origami structures as mechanical metamaterials. PMID:25099402
Photovoltaic array loss mechanisms
Gonzalez, Charles
1986-10-01
Loss mechanisms which come into play when solar cell modules are mounted in arrays are identified. Losses can occur either from a reduction in the array electrical performance or with nonoptimal extraction of power from the array. Electrical performance degradation is caused by electrical mismatch, transmission losses from cell surface soiling and steep angle of reflectance, and electrical losses from field wiring resistance and the voltage drop across blocking diodes. The second type of loss, concerned with the operating points of the array, can involve nonoptimal load impedance and limiting the operating envelope of the array to specific ranges of voltage and current. Each of the loss mechanisms are discussed and average energy losses expected from soiling, steep reflectance angles and circuit losses are calculated.
Directory of Open Access Journals (Sweden)
Guangjian Ni
2014-01-01
Full Text Available The cochlea plays a crucial role in mammal hearing. The basic function of the cochlea is to map sounds of different frequencies onto corresponding characteristic positions on the basilar membrane (BM. Sounds enter the fluid-filled cochlea and cause deflection of the BM due to pressure differences between the cochlear fluid chambers. These deflections travel along the cochlea, increasing in amplitude, until a frequency-dependent characteristic position and then decay away rapidly. The hair cells can detect these deflections and encode them as neural signals. Modelling the mechanics of the cochlea is of help in interpreting experimental observations and also can provide predictions of the results of experiments that cannot currently be performed due to technical limitations. This paper focuses on reviewing the numerical modelling of the mechanical and electrical processes in the cochlea, which include fluid coupling, micromechanics, the cochlear amplifier, nonlinearity, and electrical coupling.
Mechanisms of intergranular fracture
Energy Technology Data Exchange (ETDEWEB)
Farkas, D. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Materials Science and Engineering
1999-08-01
The authors present a study of the atomistic mechanisms of crack propagation along grain boundaries in metals and alloys. The failure behavior showing cleavage crack growth and/or crack-tip dislocation emission is demonstrated using atomistic simulations for an embedded-atom model. The simulations follow the quasi-equilibrium growth of a crack as the stress intensity applied increases. Dislocations emitted from crack tips normally blunt the crack and inhibit cleavage, inducing ductile behavior. When the emitted dislocations stay near the crack tip (sessile dislocations), they do blunt the crack but brittle cleavage can occur after the emission of a sufficient number of dislocations. The fracture process occurs as a combination of dislocation emission/micro-cleavage portions that are controlled by the local atomistic structure of the grain boundary. The grain boundary is shown to be a region where dislocation emission is easier, a mechanism that competes with the lower cohesive strength of the boundary region.
Glass, J.A.F.
1958-07-01
A reactor control mechanism is described wherein the control is achieved by the partial or total withdrawal of the fissile material which is in the form of a fuel rod. The fuel rod is designed to be raised and lowered from the reactor core area by means of two concentric ball nut and screw assemblies that may telescope one within the other. These screw mechanisms are connected through a magnetic clutch to a speed reduction gear and an accurately controllable prime motive source. With the clutch energized, the fuel rod may be moved into the reactor core area, and fine adjustments may be made through the reduction gearing. However, in the event of a power failure or an emergency signal, the magnetic clutch will become deenergized, and the fuel rod will drop out of the core area by the force of gravity, thus shutting down the operation of the reactor.
Relativistic quantum mechanics
Wachter, Armin
2010-01-01
Which problems do arise within relativistic enhancements of the Schrödinger theory, especially if one adheres to the usual one-particle interpretation, and to what extent can these problems be overcome? And what is the physical necessity of quantum field theories? In many books, answers to these fundamental questions are given highly insufficiently by treating the relativistic quantum mechanical one-particle concept very superficially and instead introducing field quantization as soon as possible. By contrast, this monograph emphasizes relativistic quantum mechanics in the narrow sense: it extensively discusses relativistic one-particle concepts and reveals their problems and limitations, therefore motivating the necessity of quantized fields in a physically comprehensible way. The first chapters contain a detailed presentation and comparison of the Klein-Gordon and Dirac theory, always in view of the non-relativistic theory. In the third chapter, we consider relativistic scattering processes and develop the...
Determinism beneath Quantum Mechanics
Hooft, G
2002-01-01
Contrary to common belief, it is not difficult to construct deterministic models where stochastic behavior is correctly described by quantum mechanical amplitudes, in precise accordance with the Copenhagen-Bohr-Bohm doctrine. What is difficult however is to obtain a Hamiltonian that is bounded from below, and whose ground state is a vacuum that exhibits complicated vacuum fluctuations, as in the real world. Beneath Quantum Mechanics, there may be a deterministic theory with (local) information loss. This may lead to a sufficiently complex vacuum state, and to an apparent non-locality in the relation between the deterministic ("ontological") states and the quantum states, of the kind needed to explain away the Bell inequalities. Theories of this kind would not only be appealing from a philosophical point of view, but may also be essential for understanding causality at Planckian distance scales.
Imaging the Antikythera Mechanism
Energy Technology Data Exchange (ETDEWEB)
Malzbender, Thomas
2012-02-10
In 1900, a party of sponge divers chanced on the wreck of a Roman merchant vessel between Crete and mainland Greece. It was found to contain numerous ancient Greek treasures, among them a mysterious lump of clay that split open to reveal ‘mathematical gears’ as it dried out. This object is now known as the Antikythera Mechanism, one of the most enlightening artifacts in terms of revealing the advanced nature of ancient Greek science and technology. In 2005 we travelled to the National Archeological Museum in Athens to apply our Reflectance Imaging methods to the mechanism in the hopes of revealing ancient writing on the device. We were successful, and along with the results of Microfocus CT imaging, epigraphers were able to decipher 3000 characters.
Mayato, R; Egusquiza, I
2002-01-01
The treatment of time in quantum mechanics is still an important and challenging open question in the foundation of the theory. This book describes the problems, and the attempts and achievements in defining, formalizing and measuring different time quantities in quantum theory, such as the parametric (clock) time, tunneling times, decay times, dwell times, delay times, arrival times or jump times. This multiauthored book, written as an introductory guide for the non-initiated as well as a useful source of information for the expert, covers many of the open questions. A brief historical overview is to be found in the introduction. It is followed by 12 chapters devoted to conceptual and theoretical investigations as well as experimental issues in quantum-mechanical time measurements. This unique monograph should attract physicists as well as philosophers of science working in the foundations of quantum physics.
Ventilation and respiratory mechanics.
Sheel, Andrew William; Romer, Lee M
2012-04-01
During dynamic exercise, the healthy pulmonary system faces several major challenges, including decreases in mixed venous oxygen content and increases in mixed venous carbon dioxide. As such, the ventilatory demand is increased, while the rising cardiac output means that blood will have considerably less time in the pulmonary capillaries to accomplish gas exchange. Blood gas homeostasis must be accomplished by precise regulation of alveolar ventilation via medullary neural networks and sensory reflex mechanisms. It is equally important that cardiovascular and pulmonary system responses to exercise be precisely matched to the increase in metabolic requirements, and that the substantial gas transport needs of both respiratory and locomotor muscles be considered. Our article addresses each of these topics with emphasis on the healthy, young adult exercising in normoxia. We review recent evidence concerning how exercise hyperpnea influences sympathetic vasoconstrictor outflow and the effect this might have on the ability to perform muscular work. We also review sex-based differences in lung mechanics.
Hierarchical Auxetic Mechanical Metamaterials
Gatt, Ruben; Mizzi, Luke; Azzopardi, Joseph I.; Azzopardi, Keith M.; Attard, Daphne; Casha, Aaron; Briffa, Joseph; Grima, Joseph N.
2015-02-01
Auxetic mechanical metamaterials are engineered systems that exhibit the unusual macroscopic property of a negative Poisson's ratio due to sub-unit structure rather than chemical composition. Although their unique behaviour makes them superior to conventional materials in many practical applications, they are limited in availability. Here, we propose a new class of hierarchical auxetics based on the rotating rigid units mechanism. These systems retain the enhanced properties from having a negative Poisson's ratio with the added benefits of being a hierarchical system. Using simulations on typical hierarchical multi-level rotating squares, we show that, through design, one can control the extent of auxeticity, degree of aperture and size of the different pores in the system. This makes the system more versatile than similar non-hierarchical ones, making them promising candidates for industrial and biomedical applications, such as stents and skin grafts.
Mechanisms of mercury bioremediation.
Essa, A M M; Macaskie, L E; Brown, N L
2002-08-01
Mercury is one of the most toxic heavy metals, and has significant industrial and agricultural uses. These uses have led to severe localized mercury pollution. Mercury volatilization after its reduction to the metallic form by mercury-resistant bacteria has been reported as a mechanism for mercury bioremediation [Brunke, Deckwer, Frischmuth, Horn, Lunsdorf, Rhode, Rohricht, Timmis and Weppen (1993) FEMS Microbiol. Rev. 11, 145-152; von Canstein, Timmis, Deckwer and Wagner-Dobler (1999) Appl. Environ. Microbiol. 65, 5279-5284]. The reduction/volatilization system requires to be studied further, in order to eliminate the escape of the metallic mercury into the environment. Recently we have demonstrated three different mechanisms for mercury detoxification in one organism, Klebsiella pneumoniae M426, which may increase the capture efficiency of mercury.
Institute of Scientific and Technical Information of China (English)
吴宁; 阮图南
1996-01-01
A quantum mechanical model with one bosonic degree of freedom is discussed in detail. Conventionally, when a quantum mechanical model is constructed, one must know the corresponding classical model. And by applying the correspondence between the classical Poisson brackets and the canonical commutator, the canonical quantization condition can be obtained. In the quantum model, study of the corresponding classical model is needed first. In this model, the Lagrangian is an operator gauge invariant. After localization, in order to keep gauge invariance, the operator gauge potential must be introduced. The Eular-Lagrange equation of motion of the dynamical argument gives the usual operator equation of motion. And the operator gauge potential just gjves a constraint. This constraint is just the usual canonical quantization condition.
Mechanics of collective unfolding
Caruel, M; Truskinovsky, L
2015-01-01
Mechanically induced unfolding of passive crosslinkers is a fundamental biological phenomenon encountered across the scales from individual macro-molecules to cytoskeletal actin networks. In this paper we study a conceptual model of athermal load-induced unfolding and use a minimalistic setting allowing one to emphasize the role of long-range interactions while maintaining full analytical transparency. Our model can be viewed as a description of a parallel bundle of N bistable units confined between two shared rigid backbones that are loaded through a series spring. We show that the ground states in this model correspond to synchronized, single phase configurations where all individual units are either folded or unfolded. We then study the fine structure of the wiggly energy landscape along the reaction coordinate linking the two coherent states and describing the optimal mechanism of cooperative unfolding. Quite remarkably, our study shows the fundamental difference in the size and structure of the folding-u...
DEFF Research Database (Denmark)
van Gelderen, Laurens; Malmquist, Linus Mattias Valdemar; Jomaas, Grunde
2015-01-01
In order to improve predictions for the burning efficiency and the residue composition of in-situ burning of crude oil, the burning mechanism of crude oil was studied in relation to the composition of its hydrocarbon mixture, before, during and after the burning. The surface temperature, flame...... height, mass loss rate and residues of three hydrocarbon liquids (n-octane, dodecane and hexadecane), two crude oils (DUC and REBCO) and one hydrocarbon liquid mixture of the aforementioned hydrocarbon liquids were studied using the Crude Oil Flammability Apparatus. The experimental results were compared...... to the predictions of four conceptual models that describe the burning mechanism of multicomponent fuels. Based on the comparisons, hydrocarbon liquids were found to be best described by the Equilibrium Flash Vaporization model, showing a constant gas composition and gasification rate. The multicomponent fuels...
Computation in Classical Mechanics
Timberlake, Todd
2007-01-01
There is a growing consensus that physics majors need to learn computational skills, but many departments are still devoid of computation in their physics curriculum. Some departments may lack the resources or commitment to create a dedicated course or program in computational physics. One way around this difficulty is to include computation in a standard upper-level physics course. An intermediate classical mechanics course is particularly well suited for including computation. We discuss the ways we have used computation in our classical mechanics courses, focusing on how computational work can improve students' understanding of physics as well as their computational skills. We present examples of computational problems that serve these two purposes. In addition, we provide information about resources for instructors who would like to include computation in their courses.
MECHANISMS OF BACTERIAL POLYHOSTALITY
Directory of Open Access Journals (Sweden)
Markova Yu.A.
2007-12-01
Full Text Available In the review data about factors of pathogenicity of the bacteria, capable to amaze both animals, and a plant are collected. Such properties of microorganisms as adhesion, secretion of some enzymes, mobility, a phenomenon of cooperative sensitivity - play an essential role at defeat of different organisms. They are used for many universal offensive strategy overcoming protection of an organism, irrespective of its evolutionary origin. Studying of these mechanisms, will allow to provide new approaches to monitoring illnesses.
Mechanisms in Impact Fragmentation
Wittel, Falk K.; Carmona, Humberto A.; Kun, Ferenc; Herrmann, Hans J.
2015-01-01
The brittle fragmentation of spheres is studied numerically by a 3D Discrete Element Model. Large scale computer simulations are performed with models that consist of agglomerates of many spherical particles, interconnected by beam-truss elements. We focus on a detailed description of the fragmentation process and study several fragmentation mechanisms involved. The evolution of meridional cracks is studied in detail. These cracks are found to initiate in the inside of the specimen with quasi...
DARPA's Big Mechanism program.
Cohen, Paul R
2015-07-16
Reductionist science produces causal models of small fragments of complicated systems. Causal models of entire systems can be hard to construct because what is known of them is distributed across a vast amount of literature. The Big Mechanism program aims to have machines read the literature and assemble the causal fragments found in individual papers into huge causal models, automatically. The current domain of the program is cell signalling associated with Ras-driven cancers.
Riskfactors and underlying mechanisms
2015-01-01
Childhood interpersonal traumatizations increase the risk for revictimizations as well as for psychological disorders like the posttraumatic stress disorder (PTSD). Different variables and mechanisms underlying revictimization are discussed in current literature. However, empiri-cal data on revictimization is poor and inconsistant. Guilt and shame following traumatic events are considered as risk factors for the development and persistence of PTSD. PTSD is frequently associated with trauma-re...
Effectively calculable quantum mechanics
Bolotin, Arkady
2015-01-01
According to mathematical constructivism, a mathematical object can exist only if there is a way to compute (or "construct") it; so, what is non-computable is non-constructive. In the example of the quantum model, whose Fock states are associated with Fibonacci numbers, this paper shows that the mathematical formalism of quantum mechanics is non-constructive since it permits an undecidable (or effectively impossible) subset of Hilbert space. On the other hand, as it is argued in the paper, if...
Cohen, Paul R.
2015-07-01
Reductionist science produces causal models of small fragments of complicated systems. Causal models of entire systems can be hard to construct because what is known of them is distributed across a vast amount of literature. The Big Mechanism program aims to have machines read the literature and assemble the causal fragments found in individual papers into huge causal models, automatically. The current domain of the program is cell signalling associated with Ras-driven cancers.
[Multiple mechanisms of depression].
Liu, Chun-Lin; Ruan, Ke-Feng; Gao, Jun-Wei; Wu, Fei; Zhang, Ji-Quan
2013-08-01
Depression is a grievous mental disease with an increasing high morbidity year by year and a serious social harm. The pathogenesises of depression is complicated and involves with multi-mechanisms and multi-organs. Recent studies demondtrate that in the nerval system and endocrine system there are many types of neurotransmitters and hormones, as well as their receptors, involved in depression. This paper reviews the research progress of depression in recent years.
Indian Academy of Sciences (India)
S. R. Verma
2006-06-01
The Sun is a mysterious star. The high temperature of the chromosphere and corona present one of the most puzzling problems of solar physics. Observations show that the solar coronal heating problem is highly complex with many different facts. It is likely that different heating mechanisms are at work in solar corona. Recent observations show that Magnetic Carpet is a potential candidate for solar coronal heating.
Mechanisms of Phosphine Toxicity
Nisa S. Nath; Ishita Bhattacharya; Andrew G. Tuck; Schlipalius, David I.; Paul R. Ebert
2011-01-01
Fumigation with phosphine gas is by far the most widely used treatment for the protection of stored grain against insect pests. The development of high-level resistance in insects now threatens its continued use. As there is no suitable chemical to replace phosphine, it is essential to understand the mechanisms of phosphine toxicity to increase the effectiveness of resistance management. Because phosphine is such a simple molecule (PH3), the chemistry of phosphorus is central to its toxicity...
Probability in quantum mechanics
Directory of Open Access Journals (Sweden)
J. G. Gilson
1982-01-01
Full Text Available By using a fluid theory which is an alternative to quantum theory but from which the latter can be deduced exactly, the long-standing problem of how quantum mechanics is related to stochastic processes is studied. It can be seen how the Schrödinger probability density has a relationship to time spent on small sections of an orbit, just as the probability density has in some classical contexts.
Acoustic Mechanical Feedthroughs
Sherrit, Stewart; Walkemeyer, Phillip; Bao, Xiaoqi; Bar-Cohen, Yoseph; Badescu, Mircea
2013-01-01
Electromagnetic motors can have problems when operating in extreme environments. In addition, if one needs to do mechanical work outside a structure, electrical feedthroughs are required to transport the electric power to drive the motor. In this paper, we present designs for driving rotary and linear motors by pumping stress waves across a structure or barrier. We accomplish this by designing a piezoelectric actuator on one side of the structure and a resonance structure that is matched to the piezoelectric resonance of the actuator on the other side. Typically, piezoelectric motors can be designed with high torques and lower speeds without the need for gears. One can also use other actuation materials such as electrostrictive, or magnetostrictive materials in a benign environment and transmit the power in acoustic form as a stress wave and actuate mechanisms that are external to the benign environment. This technology removes the need to perforate a structure and allows work to be done directly on the other side of a structure without the use of electrical feedthroughs, which can weaken the structure, pipe, or vessel. Acoustic energy is pumped as a stress wave at a set frequency or range of frequencies to produce rotary or linear motion in a structure. This method of transferring useful mechanical work across solid barriers by pumping acoustic energy through a resonant structure features the ability to transfer work (rotary or linear motion) across pressure or thermal barriers, or in a sterile environment, without generating contaminants. Reflectors in the wall of barriers can be designed to enhance the efficiency of the energy/power transmission. The method features the ability to produce a bi-directional driving mechanism using higher-mode resonances. There are a variety of applications where the presence of a motor is complicated by thermal or chemical environments that would be hostile to the motor components and reduce life and, in some instances, not be
Symmetry and quantum mechanics
Corry, Scott
2016-01-01
This book offers an introduction to quantum mechanics for professionals, students, and others in the field of mathematics who have a minimal background in physics with an understanding of linear algebra and group theory. It covers such topics as Lie groups, algebras and their representations, and analysis (Hilbert space, distributions, the spectral Theorem, and the Stone-Von Neumann Theorem). The book emphasizes the role of symmetry and is useful to physicists as it provides a mathematical introduction to the topic.
1999 Flight Mechanics Symposium
Lynch, John P. (Editor)
1999-01-01
This conference publication includes papers and abstracts presented at the Flight Mechanics Symposium held on May 18-20, 1999. Sponsored by the Guidance, Navigation and Control Center of Goddard Space Flight Center, this symposium featured technical papers on a wide range of issues related to orbit-attitude prediction, determination, and control; attitude sensor calibration; attitude determination error analysis; attitude dynamics; and orbit decay and maneuver strategy. Government, industry, and the academic community participated in the preparation and presentation of these papers.
Institute of Scientific and Technical Information of China (English)
无
2004-01-01
@@ Yang: In recent years, under the new international security environment, multilateralism has gradually played greater roles in various international and regional topics, especially in the settlement of regional security issues. Theoretically, regional multi-lateral security cooperation can increase the cost of destroying the status quo or invasion while increasing mutual confidence, alleviating feeling of security threat, decreasing or eliminating security predicament. This is caused by the limitations of the mechanism and the consideration of cost.
Statistical mechanics and fractals
Dobrushin, Roland Lvovich
1993-01-01
This book is composed of two texts, by R.L. Dobrushin and S. Kusuoka, each representing the content of a course of lectures given by the authors. They are pitched at graduate student level and are thus very accessible introductions to their respective subjects for students and non specialists. CONTENTS: R.L. Dobrushin: On the Way to the Mathematical Foundations of Statistical Mechanics.- S. Kusuoka: Diffusion Processes on Nested Fractals.
Bao, Gang; Bazilevs, Yuri; Chung, Jae-Hyun; Decuzzi,Paolo; Espinosa, Horacio D.; Ferrari, Mauro; Gao, Huajian; Hossain, Shaolie S.; Hughes, Thomas J. R.; Kamm, Roger Dale; Liu, Wing Kam; Marsden, Alison; Schrefler, Bernhard
2014-01-01
Over decades, the theoretical and applied mechanics community has developed sophisticated approaches for analysing the behaviour of complex engineering systems. Most of these approaches have targeted systems in the transportation, materials, defence and energy industries. Applying and further developing engineering approaches for understanding, predicting and modulating the response of complicated biomedical processes not only holds great promise in meeting societal needs, but also poses seri...
Design on hopping locomotion mechanism
Institute of Scientific and Technical Information of China (English)
LU Yong-kui; WU Yue-hua; YANG Jie; Hisayuki AOYAMA
2005-01-01
A new type of locomotion mechanism is introduced in this paper. With vibrating motors used in controling the movement of the hopping locomotion mechanism, the simple hopping locomotion mechanism had two motors, when the current went through the vertical motor, the vertical motor would vibrate to cause the mechanism to go forward, and when the current went through the horizontal motor, the mechanism will go around itself. A spring was added to the mechanism to change the natural frequency of the mechanism, when the frequency of the motor was equal to the natural frequency of the mechanism, the mechanism would hop resonantly. With the resonant hopping, the load of the mechanism was greatly enlarged, and some sensors could be added to the mechanism. Optical sensors were used to detect the infrared source, the current that went through the sensors related to the distance between the infrared light. Three optical sensors was put on the left, right and the front the mechanism, when the mechanism detect the special infrared source, it would turn itself to the light, and go forward to the light. The experiments of the mechanism shown that the mechanism could work well on different surfaces freely, and the resonant hopping locomotion mechanism with infrared sensors could move to the special light by automatic regulation. Experimental results and theoretical studies demonstrate that the innovative design for hopping locomotion mechanism is superior.
Time Asymmetric Quantum Mechanics
Directory of Open Access Journals (Sweden)
Arno R. Bohm
2011-09-01
Full Text Available The meaning of time asymmetry in quantum physics is discussed. On the basis of a mathematical theorem, the Stone-von Neumann theorem, the solutions of the dynamical equations, the Schrödinger equation (1 for states or the Heisenberg equation (6a for observables are given by a unitary group. Dirac kets require the concept of a RHS (rigged Hilbert space of Schwartz functions; for this kind of RHS a mathematical theorem also leads to time symmetric group evolution. Scattering theory suggests to distinguish mathematically between states (defined by a preparation apparatus and observables (defined by a registration apparatus (detector. If one requires that scattering resonances of width Γ and exponentially decaying states of lifetime τ=h/Γ should be the same physical entities (for which there is sufficient evidence one is led to a pair of RHS's of Hardy functions and connected with it, to a semigroup time evolution t_0≤t<∞, with the puzzling result that there is a quantum mechanical beginning of time, just like the big bang time for the universe, when it was a quantum system. The decay of quasi-stable particles is used to illustrate this quantum mechanical time asymmetry. From the analysis of these processes, we show that the properties of rigged Hilbert spaces of Hardy functions are suitable for a formulation of time asymmetry in quantum mechanics.
Mechanical Properties of Materials
Pelleg, Joshua
2013-01-01
The subject of mechanical behavior has been in the front line of basic studies in engineering curricula for many years. This textbook was written for engineering students with the aim of presenting, in a relatively simple manner, the basic concepts of mechanical behavior in solid materials. A second aim of the book is to guide students in their laboratory experiments by helping them to understand their observations in parallel with the lectures of their various courses; therefore the first chapter of the book is devoted to mechanical testing. Another aim of the book is to provide practicing engineers with basic help to bridge the gap of time that has passed from their graduation up to their actual involvement in engineering work. The book also serves as the basis for more advanced studies and seminars when pursuing courses on a graduate level. The content of this textbook and the topics discussed correspond to courses that are usually taught in universities and colleges all over the world, but with a differ...
Hollowood, Timothy J.
2016-07-01
In our quantum mechanics courses, measurement is usually taught in passing, as an ad-hoc procedure involving the ugly collapse of the wave function. No wonder we search for more satisfying alternatives to the Copenhagen interpretation. But this overlooks the fact that the approach fits very well with modern measurement theory with its notions of the conditioned state and quantum trajectory. In addition, what we know of as the Copenhagen interpretation is a later 1950s development and some of the earlier pioneers like Bohr did not talk of wave function collapse. In fact, if one takes these earlier ideas and mixes them with later insights of decoherence, a much more satisfying version of Copenhagen quantum mechanics emerges, one for which the collapse of the wave function is seen to be a harmless book keeping device. Along the way, we explain why chaotic systems lead to wave functions that spread out quickly on macroscopic scales implying that Schrödinger cat states are the norm rather than curiosities generated in physicists' laboratories. We then describe how the conditioned state of a quantum system depends crucially on how the system is monitored illustrating this with the example of a decaying atom monitored with a time of arrival photon detector, leading to Bohr's quantum jumps. On the other hand, other kinds of detection lead to much smoother behaviour, providing yet another example of complementarity. Finally we explain how classical behaviour emerges, including classical mechanics but also thermodynamics.
Graduate Quantum Mechanics Reform
Carr, L D
2008-01-01
We address four main areas in which graduate quantum mechanics education in the U.S. can be improved: course content; textbook; teaching methods; and assessment tools. We report on a three year longitudinal study at the Colorado School of Mines using innovations in all four of these areas. In particular, we have modified the content of the course to reflect progress in the field in the last 50 years, use modern textbooks that include such content, incorporate a variety of teaching techniques based on physics education research, and used a variety of assessment tools to study the effectiveness of these reforms. We present a new assessment tool, the Graduate Quantum Mechanics Conceptual Survey, and further testing of a previously developed assessment tool, the Quantum Mechanics Conceptual Survey (QMCS). We find that graduate students respond well to research-based techniques that have previously been tested mainly in introductory courses, and that they learn a great deal of the new content introduced in each ve...
Mechanical Design of Spacecraft
1962-01-01
In the spring of 1962, engineers from the Engineering Mechanics Division of the Jet Propulsion Laboratory gave a series of lectures on spacecraft design at the Engineering Design seminars conducted at the California Institute of Technology. Several of these lectures were subsequently given at Stanford University as part of the Space Technology seminar series sponsored by the Department of Aeronautics and Astronautics. Presented here are notes taken from these lectures. The lectures were conceived with the intent of providing the audience with a glimpse of the activities of a few mechanical engineers who are involved in designing, building, and testing spacecraft. Engineering courses generally consist of heavily idealized problems in order to allow the more efficient teaching of mathematical technique. Students, therefore, receive a somewhat limited exposure to actual engineering problems, which are typified by more unknowns than equations. For this reason it was considered valuable to demonstrate some of the problems faced by spacecraft designers, the processes used to arrive at solutions, and the interactions between the engineer and the remainder of the organization in which he is constrained to operate. These lecture notes are not so much a compilation of sophisticated techniques of analysis as they are a collection of examples of spacecraft hardware and associated problems. They will be of interest not so much to the experienced spacecraft designer as to those who wonder what part the mechanical engineer plays in an effort such as the exploration of space.
Atuanya, C. U.; Edokpia, R. O.; Aigbodion, V. S.
This work presents a systematic approach to evaluate the physio-mechanical properties of bean pod ash particles (BPAp) reinforced recycled polyethylene (RLDPE) polymer based composites. The bean pod ash particles of 75 μm with a weight percentage of 0, 5, 10, 15, 20, 25, 30 (wt%) and recycled polyethylene (RLDPE) were prepared. The surface morphology, physical and the mechanical properties of the composites were examined. The results showed that the fair distribution of the bean pod ash particles in the microstructure of the polymer composites is the major factor responsible for the improvement in the mechanical properties. The bean pod ash particles added to the RLDPE polymer increased the percentage of water absorption and improved its rigidity, modulus and hardness values of the composites. The tensile and flexural strengths increased to a maximum of 20.1 and 39.0 N/mm2 at 20 wt% BPAp respectively. Based on the results obtained in this study, it is recommended that the composites can be used in the production of indoor and outdoor applications.
Zweig, George
2016-05-01
An earlier paper characterizing the linear mechanical response of the organ of Corti [J. Acoust. Soc. Am. 138, 1102-1121 (2015)] is extended to the nonlinear domain. Assuming the existence of nonlinear oscillators nonlocally coupled through the pressure they help create, the oscillator equations are derived and examined when the stimuli are modulated tones and clicks. The nonlinearities are constrained by the requirements of oscillator stability and the invariance of zero crossings in the click response to changes in click amplitude. The nonlinear oscillator equations for tones are solved in terms of the fluid pressure that drives them, and its time derivative, presumably a proxy for forces created by outer hair cells. The pressure equation is reduced to quadrature, the integrand depending on the oscillators' responses. The resulting nonlocally coupled nonlinear equations for the pressure, and oscillator amplitudes and phases, are solved numerically in terms of the fluid pressure at the stapes. Methods for determining the nonlinear damping directly from measurements are described. Once the oscillators have been characterized from their tone and click responses, the mechanical response of the cochlea to natural sounds may be computed numerically. Signal processing inspired by cochlear mechanics opens up a new area of nonlocal nonlinear time-frequency analysis.
Relativistic viscoelastic fluid mechanics.
Fukuma, Masafumi; Sakatani, Yuho
2011-08-01
A detailed study is carried out for the relativistic theory of viscoelasticity which was recently constructed on the basis of Onsager's linear nonequilibrium thermodynamics. After rederiving the theory using a local argument with the entropy current, we show that this theory universally reduces to the standard relativistic Navier-Stokes fluid mechanics in the long time limit. Since effects of elasticity are taken into account, the dynamics at short time scales is modified from that given by the Navier-Stokes equations, so that acausal problems intrinsic to relativistic Navier-Stokes fluids are significantly remedied. We in particular show that the wave equations for the propagation of disturbance around a hydrostatic equilibrium in Minkowski space-time become symmetric hyperbolic for some range of parameters, so that the model is free of acausality problems. This observation suggests that the relativistic viscoelastic model with such parameters can be regarded as a causal completion of relativistic Navier-Stokes fluid mechanics. By adjusting parameters to various values, this theory can treat a wide variety of materials including elastic materials, Maxwell materials, Kelvin-Voigt materials, and (a nonlinearly generalized version of) simplified Israel-Stewart fluids, and thus we expect the theory to be the most universal description of single-component relativistic continuum materials. We also show that the presence of strains and the corresponding change in temperature are naturally unified through the Tolman law in a generally covariant description of continuum mechanics.
Mechanical stop mechanism for overcoming MEMS fabrication tolerances
Hussein, Hussein; Bourbon, Gilles; Le Moal, Patrice; Haddab, Yassine; Lutz, Philippe
2017-01-01
A mechanical stop mechanism is developed in order to compensate MEMS fabrication tolerances in discrete positioning. The mechanical stop mechanism is designed to be implemented on SOI wafers using a common DRIE etching process. The various fabrication tolerances obtained due to the etching process are presented and discussed in the paper. The principle and design of the mechanism are then presented. Finally, experiments on microfabricated positioning prototypes show accurate steps unaffected by the fabrication tolerances.
Mechanical stratigraphy and normal faulting
Ferrill, David A.; Morris, Alan P.; McGinnis, Ronald N.; Smart, Kevin J.; Wigginton, Sarah S.; Hill, Nicola J.
2017-01-01
Mechanical stratigraphy encompasses the mechanical properties, thicknesses, and interface properties of rock units. Although mechanical stratigraphy often relates directly to lithostratigraphy, lithologic description alone does not adequately describe mechanical behavior. Analyses of normal faults with displacements of millimeters to 10's of kilometers in mechanically layered rocks reveal that mechanical stratigraphy influences nucleation, failure mode, fault geometry, displacement gradient, displacement distribution, fault core and damage zone characteristics, and fault zone deformation processes. The relationship between normal faulting and mechanical stratigraphy can be used either to predict structural style using knowledge of mechanical stratigraphy, or conversely to interpret mechanical stratigraphy based on characterization of the structural style. This review paper explores a range of mechanical stratigraphic controls on normal faulting illustrated by natural and modeled examples.
On Foundations of Newtonian Mechanics
Cheremensky, Al
2010-01-01
Being based on V. Konoplev's axiomatic approach to continuum mechanics, the paper broadens its frontiers in order to bring together continuum mechanics with classical mechanics in a new theory of mechanical systems. There are derived motion equations of `abstract' mechanical systems specified for mass-points, multibody systems and continua: Newton-Euler equations, Lagrange equations of II kind and Navier-Stokes ones. Quasi-linear constitutive equations are introduced in conformity with V. Konoplev's definition of stress and strain (rate) matrices.
Craniofacial Pain: Brainstem Mechanisms
Directory of Open Access Journals (Sweden)
Barry J Sessle
1996-01-01
Full Text Available This article reviews recent research advances in animals that have identified critical neural elements in the brainstem receiving and transmitting craniofacial nociceptive inputs, as well as some of the mechanisms involved in the modulation and plasticity of nociceptive transmission. Nociceptive neurones in the trigeminal (V brainstem sensory nuclear complex can be classified as nociceptive-specific (NS or wide dynamic range (WDR. Some of these neurones respond exclusively to sensory inputs evoked by stimulation of facial skin or oral mucosa and have features suggesting that they are critical neural elements involved in the ability to localize an acute superficial pain and sense its intensity and duration. Many of the V brainstem nociceptive neurones, however, receive convergent inputs from afferents supplying deep craniofacial tissues (eg, dural vessel, muscle and skin or mucosa. These neurones are likely involved in deep pain, including headache, because few nociceptive neurones receive inputs exclusively from afferents supplying these tissues. These extensive convergent input patterns also appear to be important factors in pain spread and referral, and in central mechanisms underlying neuroplastic changes in V neuronal properties that may occur with injury and inflammation. For example, application of the small fibre excitant and inflammatory irritant mustard oil into the temporomandibular joint, masseter or tongue musculature induces a prolonged but reversible enhancement of responses to cutaneous and deep afferent inputs of most WDR and NS neurones. These effects may be accompanied by increased electromyographic activity reflexly induced in the masticatory muscles by mustard oil, and involve endogenous N-methyl-D-aspartate and opioid neurochemical mechanisms. Such peripherally induced modulation of brainstem nociceptive neuronal properties reflects the functional plasticity of the central V system, and may be involved in the development of
Statistical mechanics of learning
Engel, Andreas
2001-01-01
The effort to build machines that are able to learn and undertake tasks such as datamining, image processing and pattern recognition has led to the development of artificial neural networks in which learning from examples may be described and understood. The contribution to this subject made over the past decade by researchers applying the techniques of statistical mechanics is the subject of this book. The authors provide a coherent account of various important concepts and techniques that are currently only found scattered in papers, supplement this with background material in mathematics and physics, and include many examples and exercises.
Kam, J; Goldratt, E M; Barishak, Y R; Stein, R
1978-04-01
A mechanized trepan is described whose cutting action is halted automatically when the trepan's cutting edge reaches the last 0.03 mm. tissue layer of the cornea. The automatic half of both the motor which advances the trepan as well as the second motor which rotates the trepan is triggered by the sudden change in electrical resistance between the trepan and the patient's internal body fluid, at the final stage of penetration. This automatic feature eliminates the danger of inadvertant damage to the inner structures of the eye.
Analysis driven mechanical redesign
Energy Technology Data Exchange (ETDEWEB)
Ames, A.L.; Robison, R.H.
1997-08-01
This paper documents an effort to use a constrained nonlinear optimization package (OptdesX) to drive a feature-based mechanical design system (Pro/Engineer) in an optimization loop. Optimizations performed in this manner can maximally respect the design intent built into the model, and eliminate the need to propagate optimization results back to design, a flaw of most current optimization systems. A prototype system was built to demonstrate the capability; use of the prototype uncovered a variety of issues that should be addressed to productionize this kind of capability.
Introduction to continuum mechanics
Rubin, David; Lai, W Michael
1994-01-01
Continuum mechanics studies the response of materials to different loading conditions. The concept of tensors is introduced through the idea of linear transformation in a self-contained chapter, and the interrelation of direct notation, indicial notation and matrix operations is clearly presented. A wide range of idealized materials are considered through simple static and dynamic problems, and the book contains an abundance of illustrative examples and problems, many with solutions. Through the addition of more advanced material (solution of classical elasticity problems, constitutive e
Fracture mechanics safety approaches
Energy Technology Data Exchange (ETDEWEB)
Roos, E.; Schuler, X.; Eisele, U. [Materials Testing Inst. (MPA), Univ. of Stuttgart (Germany)
2004-07-01
Component integrity assessments require the knowledge of reliable fracture toughness parameters characterising the initiation of the failure process in the whole relevant temperature range. From a large number of fracture mechanics tests a statistically based procedure was derived allowing to quantify the initiation of fracture toughness as a function of temperature as a closed function as well as the temperature dependence of the cleavage instability parameters. Alternatively to the direct experimental determination one also can use a correlation between fracture toughness and notch impact energy. (orig.)
Mechanics of elastic composites
Cristescu, Nicolaie Dan; Soós, Eugen
2003-01-01
This is a comprehensive, reader-friendly treatment of the theory behind modern elastic composite materials. The treatment includes recently developed results and methods drawn from research papers published in Eastern Europe that until now were unavailable in many western countries. Among the book''s many notable features is the inclusion of more than 400 problems, many of which are solved at the end of the book. Mechanics of Elastic Composites is an outstanding textbook for graduate-level course work and a valuable reference for engineers and researchers. Developed over many years by leading
Meister, Jeffrey P.
1987-01-01
The Mechanics of Materials Model (MOMM) is a three-dimensional inelastic structural analysis code for use as an early design stage tool for hot section components. MOMM is a stiffness method finite element code that uses a network of beams to characterize component behavior. The MOMM contains three material models to account for inelastic material behavior. These include the simplified material model, which assumes a bilinear stress-strain response; the state-of-the-art model, which utilizes the classical elastic-plastic-creep strain decomposition; and Walker's viscoplastic model, which accounts for the interaction between creep and plasticity that occurs under cyclic loading conditions.
Mechanical engineering principles
Bird, John
2014-01-01
A student-friendly introduction to core engineering topicsThis book introduces mechanical principles and technology through examples and applications, enabling students to develop a sound understanding of both engineering principles and their use in practice. These theoretical concepts are supported by 400 fully worked problems, 700 further problems with answers, and 300 multiple-choice questions, all of which add up to give the reader a firm grounding on each topic.The new edition is up to date with the latest BTEC National specifications and can also be used on undergraduate courses in mecha
Quantum mechanical Carnot engine
Bender, C M; Meister, B K
2000-01-01
A cyclic thermodynamic heat engine runs most efficiently if it is reversible. Carnot constructed such a reversible heat engine by combining adiabatic and isothermal processes for a system containing an ideal gas. Here, we present an example of a cyclic engine based on a single quantum-mechanical particle confined to a potential well. The efficiency of this engine is shown to equal the Carnot efficiency because quantum dynamics is reversible. The quantum heat engine has a cycle consisting of adiabatic and isothermal quantum processes that are close analogues of the corresponding classical processes.
Mechanics of tissue compaction.
Turlier, Hervé; Maître, Jean-Léon
2015-12-01
During embryonic development, tissues deform by a succession and combination of morphogenetic processes. Tissue compaction is the morphogenetic process by which a tissue adopts a tighter structure. Recent studies characterized the respective roles of cells' adhesive and contractile properties in tissue compaction. In this review, we formalize the mechanical and molecular principles of tissue compaction and we analyze through the prism of this framework several morphogenetic events: the compaction of the early mouse embryo, the formation of the fly retina, the segmentation of somites and the separation of germ layers during gastrulation.
Incretin secretion: direct mechanisms
DEFF Research Database (Denmark)
Balk-Møller, Emilie; Holst, Jens Juul; Kuhre, Rune Ehrenreich
2014-01-01
The incretin hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) are secreted from gastro-intestinal K- and L-cells, respectively, and play an important role in post-prandial blood glucose regulation. They do this by direct stimulation of the pancreatic β...... enzyme responsible for incretin degradation (dipeptidyl peptidase-4) is inhibited (drugs are already on the market) while the secretion of endogenous GLP-1 secretion is stimulated at the same time may prove particularly rewarding. In this section we review current knowledge on the mechanisms for direct...
Molecular mechanisms in gliomagenesis
DEFF Research Database (Denmark)
Hulleman, Esther; Helin, Kristian
2005-01-01
brain development, such as the differentiation of neural stem cells (NSCs) into astrocytes, might contribute to GBM formation. These pathways include growth factor-induced signal transduction routes and processes that control cell cycle progression, such as the p16-CDK4-RB and the ARF-MDM2-p53 pathways....... The expression of several of the components of these signaling cascades has been found altered in GBM, and recent data indicate that combinations of mutations in these pathways may contribute to GBM formation, although the exact mechanisms are still to be uncovered. Use of novel techniques including large...
2001 Flight Mechanics Symposium
Lynch, John P. (Editor)
2001-01-01
This conference publication includes papers and abstracts presented at the Flight Mechanics Symposium held on June 19-21, 2001. Sponsored by the Guidance, Navigation and Control Center of Goddard Space Flight Center, this symposium featured technical papers on a wide range of issues related to attitude/orbit determination, prediction and control; attitude simulation; attitude sensor calibration; theoretical foundation of attitude computation; dynamics model improvements; autonomous navigation; constellation design and formation flying; estimation theory and computational techniques; Earth environment mission analysis and design; and, spacecraft re-entry mission design and operations.
Exactly Solvable Quantum Mechanics
Sasaki, Ryu
2014-01-01
A comprehensive review of exactly solvable quantum mechanics is presented with the emphasis of the recently discovered multi-indexed orthogonal polynomials. The main subjects to be discussed are the factorised Hamiltonians, the general structure of the solution spaces of the Schroedinger equation (Crum's theorem and its modifications), the shape invariance, the exact solvability in the Schroedinger picture as well as in the Heisenberg picture, the creation/annihilation operators and the dynamical symmetry algebras, coherent states, various deformation schemes (multiple Darboux transformations) and the infinite families of multi-indexed orthogonal polynomials, the exceptional orthogonal polynomials, and deformed exactly solvable scattering problems.
Directory of Open Access Journals (Sweden)
Chen Rou-Xi
2013-01-01
Full Text Available Fabrication of crimped fibers has been caught much attention recently due to remarkable improvement surface-to-volume ratio. The precise mechanism of the fiber crimp is, however, rare and preliminary. This paper finds that pulsation of fibers is the key factor for fiber crimp, and its configuration (wave formation corresponds to its nature frequency after solidification. Crimping performance can be improved by temperature control of the uncrimped fibers. In the paper, polylactide/ dimethylfomamide solution is fabricated into crimped nanofibers by the bubble electrospinning, an approximate period- amplitude relationship of the wave formation is obtained.
Mechanics of artificial microcapsules
Energy Technology Data Exchange (ETDEWEB)
Fery, A; Dubreuil, F; Moehwald, H [Max-Planck Institute of Colloids and Interfaces, D 14424 Potsdam (Germany)
2004-02-01
In recent years, an increasing number of microcapsule systems have been realized and have found applications in various fields of research and technology. Amongst others, polyelectrolyte multilayer capsules (PMCs) offer a great variety of materials and superior control over the wall thicknesses. We present here a review on the different techniques that are available for characterizing the mechanical properties of PMCs. We compare results that were obtained using these techniques on the same system, namely PMCs made from polyallylamine and polystyrenesulfonate multilayers and discuss perspectives of the field.
Nanoantenna using mechanical resonance
Chang Hwa Lee,
2010-11-01
Nanoantenna using mechanical resonance vibration is made from an indium tin oxide (ITO) coated vertically aligned nanorod array. Only this structure works as a radio with demodulator without any electrical circuit using field emission phenomenon. A top-down fabrication method of an ITO coated nanorod array is proposed using a modified UV lithography. The received radio frequency and the resonance frequency of nanoantenna can be controlled by the fabrication condition through the height of a nanorod array. The modulated signals are received successfully with the transmission carrier wave frequency (248MHz) and the proposed nanoantenna is expected to be used in communication system for ultra small scale sensor. ©2010 IEEE.
Submicroscopic Deterministic Quantum Mechanics
Krasnoholovets, V
2002-01-01
So-called hidden variables introduced in quantum mechanics by de Broglie and Bohm have changed their initial enigmatic meanings and acquired quite reasonable outlines of real and measurable characteristics. The start viewpoint was the following: All the phenomena, which we observe in the quantum world, should reflect structural properties of the real space. Thus the scale 10^{-28} cm at which three fundamental interactions (electromagnetic, weak, and strong) intersect has been treated as the size of a building block of the space. The appearance of a massive particle is associated with a local deformation of the cellular space, i.e. deformation of a cell. The mechanics of a moving particle that has been constructed is deterministic by its nature and shows that the particle interacts with cells of the space creating elementary excitations called "inertons". The further study has disclosed that inertons are a substructure of the matter waves which are described by the orthodox wave \\psi-function formalism. The c...
Mechanical engineering in hospitals.
Wallington, J W
1980-10-01
The design of a modern hospital owes more to engineering than the layman may realize. In this context, many engineers are in the position of laymen, being unfamiliar with the multitude of services that lies behind the impressive facade of a modern hospital. In recent years medicine and surgery themselves have taken on many of the characteristics of a technology. This has required a matching development of the services both mechanical and electrical that are required in modern health care buildings. In medical terms, if the architectural features provide the 'skin' of the hospital, the mechanical and electrical engineering services provide the nerves and sinews. If we take as an example the recently completed Freeman Hospital, Newcastle upon Tyne, (Fig. 1), which cost 10 million pounds at current cost, the service network was responsible for about half the total cost. About 400 miles (643 km) of electrical wiring and more than 40 mile (64.5 km) of copper and steel piping were used to service 3000 separate rooms. This compares with percentages of between 18 and 25 per cent for other large buildings such as office blocks, hotels and sports complexes.
Particle acceleration mechanisms
Petrosyan, V
2008-01-01
We review the possible mechanisms for production of non-thermal electrons which are responsible for non-thermal radiation in clusters of galaxies. Our primary focus is on non-thermal Bremsstrahlung and inverse Compton scattering, that produce hard X-ray emission. We briefly review acceleration mechanisms and point out that in most astrophysical situations, and in particular for the intracluster medium, shocks, turbulence and plasma waves play a crucial role. We consider two scenarios for production of non-thermal radiation. The first is hard X-ray emission due to non-thermal Bremsstrahlung by nonrelativistic particles. Non-thermal tails are produced by accelerating electrons from the background plasma with an initial Maxwellian distribution. However, these tails are accompanied by significant heating and they are present for a short time of <10^6 yr, which is also the time that the tail will be thermalised. Such non-thermal tails, even if possible, can only explain the hard X-ray but not the radio emission...
Basdevant, Jean-Louis
2007-01-01
Beautifully illustrated and engagingly written, Lectures on Quantum Mechanics presents theoretical physics with a breathtaking array of examples and anecdotes. Basdevant's style is clear and stimulating, in the manner of a brisk classroom lecture that students can follow with ease and enjoyment. Here is a sample of the book's style, from the opening of Chapter 1: "If one were to ask a passer-by to quote a great formula of physics, chances are that the answer would be 'E = mc2'. Nevertheless, the formula 'E=hV' which was written in the same year 1905 by the same Albert Einstein, and which started quantum theory, concerns their daily life considerably more. In fact, of the three watershed years for physics toward the beginning of the 20th century - 1905: the Special Relativity of Einstein, Lorentz and Poincaré; 1915: the General Relativity of Einstein, with its extraordinary reflections on gravitation, space and time; and 1925: the full development of Quantum Mechanics - it is surely the last which has the mos...
Thymoquinone: Novel gastroprotective mechanisms.
Magdy, Mahmoud-Awny; Hanan, El-Abhar; Nabila, El-Maraghy
2012-12-15
Ample of evidence proved the gastroprotective effect of thymoquinone (TQ), the main constituent of Nigella sativa oil; however, the full mechanistic cassette on the gastric ulcer etiopathogenesis is not fully elucidated. The aim of the present work is to unveil some of the possible mechanisms. Animals were injected with vehicle, TQ (10 & 20mg/kg), omeprazole (10 & 20mg/kg) or their combination (10mg/kg). Thirty minutes later, pyloric ligation was carried out and followed consequently with ischemia for another 30min, abided by reperfusion for 120min. The ischemia/reperfusion insult increased the gastric acid secretion, acid output, and pepsin, as well as the gastric mucosal content/activity of lipid peroxide, proton pump and myeloperoxidase, along with ulcer index. However, content/activity of gastric mucin, reduced glutathione, total nitric oxide, and superoxide dismutase were decreased. TQ, especially the high dose level, corrected the altered parameters in a comparable manner to that of the reference drug used, omeprazole. In addition, when the low doses were combined they add to each other to reach the effect of the high dose of either drug. These results showed that apart from its known antioxidant properties, TQ has novel gastroprotective mechanisms via inhibiting proton pump, acid secretion and neutrophil infiltration, while enhancing mucin secretion, and nitric oxide production.
Peripheral Auditory Mechanisms
Hall, J; Hubbard, A; Neely, S; Tubis, A
1986-01-01
How weIl can we model experimental observations of the peripheral auditory system'? What theoretical predictions can we make that might be tested'? It was with these questions in mind that we organized the 1985 Mechanics of Hearing Workshop, to bring together auditory researchers to compare models with experimental observations. Tbe workshop forum was inspired by the very successful 1983 Mechanics of Hearing Workshop in Delft [1]. Boston University was chosen as the site of our meeting because of the Boston area's role as a center for hearing research in this country. We made a special effort at this meeting to attract students from around the world, because without students this field will not progress. Financial support for the workshop was provided in part by grant BNS- 8412878 from the National Science Foundation. Modeling is a traditional strategy in science and plays an important role in the scientific method. Models are the bridge between theory and experiment. Tbey test the assumptions made in experim...
Curtis, Clifford M.
1995-05-01
An elastomeric shutter mechanism for opening and closing a passageway in the wall of a vessel, such as a submarine hull is presented. A single, unitary, retractable shutter member made of an elastomeric material is partially attached to the wall around a portion of a passageway. The single, unitary, retractable shutter member is moveable from a closed position when the unattached portion of the shutter member is abutting the wall around the passageway to an open position when the unattached portion of the shutter member is retracted away from the wall around the passageway. Cables are attached to the inside surface of the shutter member for retracting the shutter member and opening the passageway. Mechanical stops are positioned inside of the vessel for abutting the shutter member when retracted to the open position by the cables. On an underwater vessel such as a submarine, the shutter member is sealed in the closed position by a pressure differential between the inside surface and the outside surface of the shutter member or latched in place in the closed position. Split ribs are included on the inside surface of the shutter member to resist the expansion of the shutter member when maintained in the closed position by the pressure differential.
Mechanical Properties of Cells
Bradley, Robert; Becerril, Joseph; Jeevarajan, Anthony
2007-01-01
Many physiologic and pathologic processes alter the biomechanical properties of the tissue they affect, and these changes may be manifest at the single cell level. The normal and abnormal mechanical properties of a given cell type can be established with the aid of an atomic force microscope (AFM), nonetheless, consistency in the area of the tip has been a mayor limitation of using the AFM for quantitative measurements of mechanical properties. This project attempts to overcome this limitation by using materials with a known elastic modulus, which resembles the one of the cell, to create force-deformation curves to calculate the area of indentation by means of Hooke s Law (sigma = E(epsilon)), which states that stress (sigma) is proportional to the strain (epsilon) where the constant of proportionality, E, is called the Young s modulus, also referred as the elastic modulus. Hook s Law can be rearranged to find the area of indentation (Area= Force/ E(epsilon)), where the indentation force is defined by the means of the added mass spring calibration method.
Elements of Statistical Mechanics
Sachs, Ivo; Sen, Siddhartha; Sexton, James
2006-05-01
This textbook provides a concise introduction to the key concepts and tools of modern statistical mechanics. It also covers advanced topics such as non-relativistic quantum field theory and numerical methods. After introducing classical analytical techniques, such as cluster expansion and Landau theory, the authors present important numerical methods with applications to magnetic systems, Lennard-Jones fluids and biophysics. Quantum statistical mechanics is discussed in detail and applied to Bose-Einstein condensation and topics in astrophysics and cosmology. In order to describe emergent phenomena in interacting quantum systems, canonical non-relativistic quantum field theory is introduced and then reformulated in terms of Feynman integrals. Combining the authors' many years' experience of teaching courses in this area, this textbook is ideal for advanced undergraduate and graduate students in physics, chemistry and mathematics. Analytical and numerical techniques in one text, including sample codes and solved problems on the web at www.cambridge.org/0521841984 Covers a wide range of applications including magnetic systems, turbulence astrophysics, and biology Contains a concise introduction to Markov processes and molecular dynamics
Energy Technology Data Exchange (ETDEWEB)
Lister, Derek H. [New Brunswick Univ., Fredericton, NB (Canada). Dept. of Chemical Engineering; Uchida, Shunsuke [Institute of Applied Energy, Tokyo (Japan)
2010-10-15
Flow-accelerated corrosion of carbon steel in steam-raising systems is obviously dominated by fluid-dynamic parameters such as turbulence and by water chemistry that promotes dissolution of the normally protective magnetite film; the mechanism is often formulated simply as the product of the mass transfer coefficient and the undersaturation in dissolved iron. Additives to the coolant, such as dissolved oxygen or ammonia, and elements in the steel, such as chromium, are then considered to inhibit flow-accelerated corrosion (FAC) by making the magnetite less soluble. This approach can be useful for predicting locations susceptible to FAC and for supporting proposals for palliative treatments, for example. It is rarely an accurate predictor of FAC rate, however, which may be attributable to its being applied in situations where surface reactions play a part. These issues are discussed in the light of recent research results and it is suggested that mechanisms introducing elements of mixed control may often be more appropriate. (orig.)
Quantum mechanics of materials
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Cohen, M.L.; Heine, V.; Phillips, J.C.
1982-06-01
In the past 25 years, new quantum-mechanical methods have been developed for predicting the configuration of the valence electrons in an atom or an aggregate of many atoms, within the range of energy excitations in which the atoms form interatomic bonds. A theory specifying the configuration of the valence electrons has much to say about the bulk properties of matter that depends on the nature of the interatomic bonds. The new method regards the core electrons and the atomic nucleus as if they constituted a single particle without internal structure. The method is called the pseudopotential theory. A general quantum-mechanical prediction of the properties of a substance in terms of the additive properties of separate chemical bonds is not yet feasible for molecules. However, there is one realm where prediction is now practical: crystalline solids. The regularity of the lattice into which the atoms are organized in a crystal makes it possible to calculate the properties of a macroscopic solid. In other words, many properties of an elemental solid such as lead or a simple binary solid such as gallium arsenide can not be deduced from energy considerations alone. (SC)
Hollowood, Timothy J
2015-01-01
In our quantum mechanics courses, measurement is usually taught in passing, as an ad-hoc procedure involving the ugly collapse of the wave function. No wonder we search for more satisfying alternatives to the Copenhagen interpretation. But this overlooks the fact that the approach fits very well with modern measurement theory with its notions of the conditioned state and quantum trajectory. In addition, what we know of as the Copenhagen interpretation is a later 1950's development and some of the earlier pioneers like Bohr did not talk of wave function collapse. In fact, if one takes these earlier ideas and mixes them with later insights of decoherence, a much more satisfying version of Copenhagen quantum mechanics emerges, one for which the collapse of the wave function is seen to be a harmless book keeping device. Along the way, we explain why chaotic systems lead to wave functions that spread out quickly on macroscopic scales implying that Schrodinger cat states are the norm rather than curiosities generat...
Clonus: definition, mechanism, treatment
Directory of Open Access Journals (Sweden)
Ismail Boyraz
2015-02-01
Full Text Available Clonus is involuntary and rhythmic muscle contractions caused by a permanent lesion in descending motor neurons. Clonus may be found at the ankle, patella, triceps surae, wrist, jaw, biceps brachii. In general, clonus may occur in any muscle with a frequency of 5-8 Hz and the average period of oscillations of the ankle clonus is approximately 160–200 ms. Plantar flexion (PF comprises 45% of the period, dorsifleksion (DF comprises 55% of the period. The first beat is always longer, with the time shortening in continuing beats and becoming stable in the 4th or 5th period. The exact mechanism of clonus remains unclear. Two different hypotheses have been asserted regarding the development of clonus. The most widely accepted explanation is that hyperactive stretch reflexes in clonus are caused by self-excitation. Another alternative explanation for clonus is central generator activity that arises as a consequence of appropriate peripheral events and produces rhythmic stimulation of the lower motor neurons. The durations of clonus burst were found longer than the durations of Soleus medium-latency reflex (MLR. There is a similarity in their nature, although the speed and cause of the stretch of triceps surae differ in the MLR and the clonus, and there is a sufficient period of time for group II afferents and for other spinal mechanisms to be involved in the clonus, together with Ia afferents. Clonus can be treated by using baclofen, applying cold, botox or phenol injections.
[Antimicrobial mechanisms of action].
Calvo, Jorge; Martínez-Martínez, Luis
2009-01-01
A large number of families and groups of antimicrobial agents are of clinical interest. The mechanisms by which compounds with antibacterial activity inhibit growth or cause bacterial death are varied and depend on the affected targets. The bacterial cell wall-a unique structure in most bacteria that is absent in eukaryotic cells-can be affected in several ways: at different stages of synthesis (fosfomycin, cycloserine) or transport (bacitracin, mureidomycins) of its metabolic precursors, or by a direct action on its structural organization (beta-lactams, glycopeptides). The main drugs affecting the cytoplasmic membrane are polymyxins and daptomycin. Protein synthesis can be blocked by a large variety of compounds that affect any of the phases of this process, including activation (mupirocin), initiation (oxazolidinones, aminoglycosides), binding of the tRNA amino acid complex to ribosomes (tetracyclines, glycylcyclines) and elongation (amphenicols, lincosamides, macrolides, ketolides, streptogramins, fusidic acid). The metabolism of nucleic acids can be altered at the DNA-dependent RNA polymerase or in the process of DNA coiling (quinolones); some compounds affect DNA directly (nitroimidazoles, nitrofurans). Trimethoprim and sulfamides (often used in combination) are examples of antimicrobial agents that block bacterial metabolic pathways. Some compounds are unable to inhibit or kill bacteria in themselves, but can block bacterial mechanisms of resistance, enhancing the activity of other antimicrobials administered in combination. Among this group of agents, only certain beta-lactamase inhibitors are currently in clinical use.
Nucleation Mechanism for Bainite
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
Based on the experimental results that solute-depleted zone was observed in Cu-28Zn-4Al (mass fraction) at 523 K,△G is calculated as a positive according to the thermodynamic criteria for the spinodal decomposition of a ternarysystems. So, the solute-depleted zone cannot be formed by spinodal decomposition. Dislocation density requiredby the formation of solute-depleted zone is estimated greater than 7.89×109 cm-2 according to the segregationof solute atoms around dislocations, which is not consistent with the practical situation for the alloy at 523 K.Associated with the internal friction experimental fact that internal friction peaks appear within the incubation forbainitic transformation in Cu-Zn-Al alloy, the equilibrium temperature, T0, is evaluated as 433 K for solute-depletedCu-25Zn-3.4Al, which is lower than the experimental temperature 523 K. Thus, nucleation by shear mechanism isimpossible in this circumstance. Therefore, it is concluded that , like bainite in steels and Ag-Cd, bainite in Cu-Zn-Alalloys nucleates by diffusional mechanism, just implied by the experimental existence of solute-depleted zone.
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Turchaninov, I.A.; Iofis, M.A.; Kasparyan, E.V.
1979-01-01
This book presents the principles of rock mechanics in a systematic way, reflecting both the historic development and the contemporary status of theoretical and experimental techniques used for the determination of the properties and stress state of rock masses, calculation of elements of systems for exploitation of useful mineral deposits and the design of mine openings. The subject of rock mechanics is discussed and methods and basic approaches are analyzed. The most widely used methods for determining the properties of rock in specimens and in situ are described. Problems of determining the stress strain state of the rock around mine openings by both experimental and analytic methods are discussed. The primary results of the study of the stress state of rock around main, development and production openings are presented. Problems of the movement of rock due to extraction of minerals are analyzed in detail, as are the conditions and causes of the development of rock bursts and sudden release of rock and gas in both surface and underground mines. Procedures for preventing or localizing rock bursts or sudden outbursts are described. (313 refs.)
[Inflammasome: activation mechanisms].
Suárez, Raibel; Buelvas, Neudo
2015-03-01
Inflammation is a rapid biologic response of the immune system in vascular tissues, directed to eliminate stimuli capable of causing damage and begin the process of repair. The macromolecular complexes known as "inflammasomes" are formed by a receptor, either NOD (NLR) or ALR, the receptor absent in melanoma 2 (AIM2). In addition, the inflammasome is formed by the speck-like protein associated to apoptosis (ASC) and procaspase-1, that may be activated by variations in the ionic and intracellular and extracellular ATP concentrations; and the loss of stabilization of the fagolisosomme by internalization of insoluble crystals and redox mechanisms. As a result, there is activation of the molecular platform and the processing of inflammatory prointerleukins to their active forms. There are two modalities of activation of the inflammasome: canonical and non-canonical, both capable of generating effector responses. Recent data associate NLRP 3, IL-1β and IL-18 in the pathogenesis of a variety of diseases, including atherosclerosis, type II diabetes, hyperhomocysteinemia, gout, malaria and hypertension. The inflammasome cascade is emerging as a new chemotherapeutic target in these diseases. In this review we shall discuss the mechanisms of activation and regulation of the inflammasome that stimulate, modulate and resolve inflammation.
Biochemical mechanisms underlying atherogenesis
Directory of Open Access Journals (Sweden)
Dr.P.V.L.N. Srinivasa Rao
2012-02-01
Full Text Available Atherosclerosis remains one of the major causes of death and premature disability in developed countries. Though atherosclerosis was formerly considered a bland lipid storage disease, substantial advances in basic and experimental sciences have illuminated the role of endothelium, inflammation and immune mechanisms in its pathogenesis. Current concept of atherosclerosis is that of a dynamic and progressive disease arising from in- jury to endothelium, also known as endothelial dysfunction and an inflammatory response to that injury. The lesions of atherosclerosis occur principally in large and medium sized arteries. Atherosclerosis affects various regions of the circulation preferentially and can lead to ischemia of heart, brain or extremities resulting in in- farction.This produces distinct clinical manifestations depending on the vessel involved. Several predisposing factors to cardiovascular diseases such as diabetes mellitus, hypertension, obesity, infections act as triggers to the devel- opment of atherosclerosis by causing endothelial dysfunction and/or promoting inflammatory response. The evolution of pathogenetic mechanisms has passed through various directions such as oxidative stress, inflam- mation and immune responses. It is now known that all these are not acting independently but are interrelated and getting unified in the current concept of atherogenesis. The following discussion aims at providing an in- sight into these developments which can help in a better comprehension of the disease and management of its clinical complications
Institute of Scientific and Technical Information of China (English)
李嘉; 李琳; 张勇军; 李钦豪
2014-01-01
为研究太阳系天体相对地球某点的运动规律，首先建立了地心黄道坐标系，并将太阳绕地球的圆周运动转换为太阳绕地心的余弦波动，同时将此余弦波动作为标准余弦曲线．将太阳绕地球的运动分解为波动和“自转”，并分双波动坐标轴和波动-螺面坐标轴分析，推导出太阳对地球赤道某点的波动式螺线运动轨迹方程，同时进行计算机模拟与分析，得到了太阳对地球某纬度某点的波动式螺线运动轨迹方程．以此类推，推导出月球对地球某点的波动式螺线运动轨迹方程，并分别进行计算机模拟与分析．结果表明，太阳、月球相对于地球某点的运动轨迹为与幅值与角度相关的波动式螺线，向x轴方向等速传播，并且：①在双波动坐标轴下分析，太阳、月球在z轴上的波动极其细微，可以近似为经典力学中的平面波动；螺线呈周期性变化，且在坐标3个平面上的投影均为周期性波动函数；整体传播呈现薄膜状波动面；月球运动变化方向复杂．②在波动-螺面坐标轴下分析，x轴与z轴数量级可比拟，z轴与x轴最大幅值之比约等于2／5；螺线波动是由起始点沿阿基米德螺线绕余弦波动面的周期性传播，螺线旋转角速度同地球自转角速度，旋转线速度与太阳、月球1年中波动的周期数相关；整体传播呈现薄膜状波动面．③太阳、月球相对于地球上某纬度c某点与赤道某点，在波动-螺面坐标轴下分析，螺线方程不变，在双波动坐标轴下分析，将太阳、月球相对于赤道某点的螺线参数方程的z轴表达式中的cos （0.37π）换为cos （0.37π＋c）得到相对于某纬度c某点的螺线参数方程．%In order to study the motion of celestial bodies in solar system relative to a certain point on the Earth, a geocentric ecliptic coordinate axis was built at first , and the sun's circling
1st National Mechanics Congress
Nieuwstadt, F
1990-01-01
The Department of Applied Mechanics of the Royal Institution of Engineers in the Netherlands (Koninklijk Instituut van Ingenieurs) organised on April 2-4, 1990 the first National Applied Mechanics Congress about the theme: "Integration of Theory and Applications in Applied Mechanics" The idea behind this initiative was to bring together the Applied Mechanics communities in The Netherlands and Belgium and to create an environment in which new developments in the field could be discussed and in which connections to other disciplines could be established. Among an extensive list of possible subjects the following were selected as congress topics: - non-linear material behaviour, - chaos, - mechatronics, - liquid-solid interactions, - mathematics and applied mechanics, - integration of Applied Mechanics and other disciplines. Applied Mechanics comprises both solid mechanics and fluid mechanics. These can be subdivided further into: rheology, plasticity, theory of plates and shells, theory of elasticity, multibody...
Mechanical and geometric advantages in compliant mechanism optimization
Institute of Scientific and Technical Information of China (English)
Michael Yu WANG
2009-01-01
This paper presents a focused examination of the mechanical and geometric advantages in compliant mechanisms and their ramifications in the design formula-tions of compliant mechanisms posed as a topology optimization problem. With a linear elastic structuralanalysis, we quantify mechanical (and geometric) advan-tage in terms of the stiffness elements of the mechanism's structure. We then analyze the common formulations of compliant mechanism optimization and the role of the external springs added in the formulations. It is shown that the common formulations using mechanical (or geometric) advantage would directly emulate at best a rigid-body linkage to the true optimum design. As a result, the topology optimization generates point flexures in the resulting optimal mechanisms. A case study is investigated to demonstrate the resulting trends in the current formula-tions.
Energy Technology Data Exchange (ETDEWEB)
Laouafa, F.; Kazmierczak, J.B. [Institut National de l' Environnement Industriel et des Risques (INERIS), Parc Technologique ALATA, 60 - Verneuil en Halatte (France); Armand, G. [Agence Nationale pour la Gestion des Dechets Radioactifs, Lab. de Souterrain de Meuse/Haute-Marne, 55 - Bure (France); Vaunat, J. [Catalonia UPC- Technical Univ., Barcelona (Spain); Jobmann, M.; Polster, M. [DBETEC- DBE Technology GmbH, Peine (Germany); Su, K.; Lebon, P.; Plas, F.; Armand, G.; Abou-Chakra Guery, A.; Cormery, F.; Shao, J.F.; Kondo, D. [ANDRA - Agence Nationale pour la Gestion des Dechets Radioactifs, 92 - Chatenay Malabry (France); Souley, M. [Institut National de l' Environnement Industriel et des Risques (INERIS), 54 - Nancy (France); Coll, C.; Charlier, R.; Collin, F.; Gerard, P. [Liege Univ., Dept. ArGEnCo (Belgium); Xiang Ling, Li [ESV EURIDICE, SCK.CEN, Belgian Nuclear Research Centre, Mol (Belgium); Collin, F. [Liege Univ., Charge de Recherches FNRS (Belgium); Pellet, F.L.; Fabre, G. [University Joseph Fourier, Laboratory 3S-R, 38 - Grenoble (France); Garcia-Sineriz, J.L.; Rey, M. [AITEMIN - Asociacion para la Investigacion y Desarrollo Industrial de los Recursos Naturales, Madrid (Spain); Mayor, J.C. [ENRESA - Empresa Nacional des Residuos Radioactivos, Madrid (Spain); Castellanos, E.; Romero, E.; Lloret, A.; Gens, A. [Catalunya Univ. Politecnica, UPC (Spain); Villar, M.V. [CIEMAT - Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Madrid (Spain); Chambon, R. [Laboratoire 3S, UJF-INPG-CNRS, 38 - Grenoble (France); Czaikowski, O.; Lux, K.H. [Clausthal Univ. of Technology, Professorship for Waste Disposal and Geomechanics, Clausthal-Zellerfeld (Germany); Van Geet, M.; Bastiaens, W.; Volckaert, G.; Weetjens, E.; Sillen, X. [SCK-CEN, Waste and Disposal dept., Mol (Belgium); ONDRAF/NIRAS, Brussel (Belgium); Imbert, Ch. [CEA Saclay, Dept. de Physico-Chimie (DPC/SCCME/LECBA), 91 - Gif sur Yvette (France)] [and others
2007-07-01
This session gathers 13 articles dealing with: three-dimensional and time stepping modelling of the whole Meuse/Haute-Marne ANDRA URL (F. Laouafa, J.B. Kazmierczak, G. Armand, J. Vaunat, M. Jobmann, M. Polster); a constitutive model for a deep argillaceous rock using Hoek-Brown criteria (K. Su, C. Chavant, M. Souley); the long term behaviour of the Boom clay: influence of viscosity on the pore pressure distribution (C. Coll, R. Charlier, X.L. Li, F. Collin); the microstructural changes induced by viscoplastic deformations in argillaceous rocks (F.L. Pellet, G. Fabre, K. Su, P. Lebon); the engineered barrier experiment at Mont Terri rock laboratory (J.L. Garcia-Sineriz, M. Rey, J.C. Mayor); the chemical influence on the Hydro-Mechanical behaviour of high-density FEBEX bentonite (E. Castellanos, M.V. Villar, E. Romero, A. Lloret, A. Gens); the influence of water exchanges on the gallery convergence (P. Gerard, R. Charlier, R. Chambon, F. Collin); a new method for ageing resistant storage of argillaceous rock samples to achieve reproducible experimental results even after long intermediate storage times (O. Czaikowski, K.H. Lux); the installation and evaluation of a large-scale in-situ shaft seal experiment in Boom clay the RESEAL project M. Van Geet, W. Bastiaens, G. Volckaert, E. Weetjens, X. Sillen, A. Gens, M.V. Villar, Ch. Imbert, M. Filippi, F. Plas); the hydro-Mechanical response of the Callovo-Oxfordian mud-stone around a deep vertical drift (J. Vaunat, B. Garitte, A. Gens, K. Su, G. Armand); the sensitivity of total stress to changes in externally applied water pressure in KBS-3 buffer bentonite (J.F. Harrington, D.J. Birchall, P. Sellin); the comparison of the poro-elastic behavior of Meuse/Haute Marne and Tournemire argillites: effect of loading and saturation states (E. Bemer, A. Noiret, F. Homand, A. Rejeb); and the multi-scale modelling of the argillites mechanical behaviour (A. Abou-Chakra Guery, F. Cormery, K. Su, J.F. Shao, D. Kondo)
Martel, S. J.
2015-12-01
Physical breakdown of rock across a broad scale spectrum involves fracturing. In many areas large fractures develop near the topographic surface, with sheeting joints being among the most impressive. Sheeting joints share many geometric, textural, and kinematic features with other joints (opening-mode fractures) but differ in that they are (a) discernibly curved, (b) open near the topographic surface, and (c) form subparallel to the topographic surface. Where sheeting joints are geologically young, the surface-parallel compressive stresses are typically several MPa or greater. Sheeting joints are best developed beneath domes, ridges, and saddles; they also are reported, albeit rarely, beneath valleys or bowls. A mechanism that accounts for all these associations has been sought for more than a century: neither erosion of overburden nor high lateral compressive stresses alone suffices. Sheeting joints are not accounted for by Mohr-Coulomb shear failure criteria. Principles of linear elastic fracture mechanics, together with the mechanical effect of a curved topographic surface, do provide a basis for understanding sheeting joint growth and the pattern sheeting joints form. Compressive stresses parallel to a singly or doubly convex topographic surface induce a tensile stress perpendicular to the surface at shallow depths; in some cases this alone could overcome the weight of overburden to open sheeting joints. If regional horizontal compressive stresses, augmented by thermal stresses, are an order of magnitude or so greater than a characteristic vertical stress that scales with topographic amplitude, then topographic stress perturbations can cause sheeting joints to open near the top of a ridge. This topographic effect can be augmented by pressure within sheeting joints arising from water, ice, or salt. Water pressure could be particularly important in helping drive sheeting joints downslope beneath valleys. Once sheeting joints have formed, the rock sheets between
Principles of discrete time mechanics
Jaroszkiewicz, George
2014-01-01
Could time be discrete on some unimaginably small scale? Exploring the idea in depth, this unique introduction to discrete time mechanics systematically builds the theory up from scratch, beginning with the historical, physical and mathematical background to the chronon hypothesis. Covering classical and quantum discrete time mechanics, this book presents all the tools needed to formulate and develop applications of discrete time mechanics in a number of areas, including spreadsheet mechanics, classical and quantum register mechanics, and classical and quantum mechanics and field theories. A consistent emphasis on contextuality and the observer-system relationship is maintained throughout.