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Topic: Lagrangian


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  Lagrangian point - Wikipedia, the free encyclopedia
The Lagrangian points (IPA: [lə.'grɒn.dʒi.ən] or [la.'grã.ʒi.ən]; also Lagrange point, L-point, or libration point), are the five positions in interplanetary space where a small object affected only by gravity can theoretically be stationary relative to two larger objects (such as a satellite with respect to the Earth and Moon).
The Lagrangian points constructed at each point in time as in the circular case form stationary elliptical orbits which are similar to the orbits of the massive bodies.
This fact is independent of the circularity of the orbits, and it implies that the elliptical orbits traced by the Lagrangian points are solutions of the equation of motion of the third body.
en.wikipedia.org /wiki/Lagrangian_point   (2070 words)

  
 Lagrangian mechanics Info - Encyclopedia WikiWhat.com
Lagrangian mechanics is a re-formulation of classical mechanics introduced by Joseph Louis Lagrange in 1788.
In Lagrangian mechanics, the trajectory of an object is derived by finding the path which minimizes the action which is the sum of the Lagrangian over time; this being the kinetic energy minus the potential energy.
The Hamiltonian, denoted by H, is obtained by performing a Legendre transformation on the Lagrangian.
wikiwhat.com /encyclopedia/l/la/lagrangian_mechanics.html   (825 words)

  
 Lagrangian Particles   (Site not responding. Last check: 2007-11-05)
While the underlying computational scheme used in the PIC method employs a fixed Eulerian grid, Lagrangian particles are used to move mass, momentum and energy through this grid in a way that preserves the identities of the different materials.
Lagrangian particles are, in fact, the key feature in the PIC method that allows it to track large fluid deformations.
Lagrangian particles are an extremely useful computational tool, especially when they are used to track small amounts of material whose dispersion is to be minimized.
www.flow3d.com /CFD-101/lagrpart.htm   (1799 words)

  
 Lagrangian points
Lagrangian points are named after the Italian-born French mathematician and astronomer Joseph Louis de Lagrange who first showed their existence.
There are five Lagrangian points in all, three of which are unstable because the slightest disturbance to any object located at one of them causes the object to drift away permanently.
The remaining two Lagrangian points, L4 and L5, lie at the vertices of equilateral triangles formed with the two main gravitating masses and in their orbital plane.
www.daviddarling.info /encyclopedia/L/Lagpoint.html   (469 words)

  
 Lagrangian - Wikipedia, the free encyclopedia
The same principle, and the Lagrange formalism, are tied closely to Noether's Theorem, which relates physical conserved quantities to continuous symmetries of a physical system; and Lagrangian mechanics and Noether's Theorem together yield a natural formalism for first quantization by including commutators between certain terms of the Lagrangian equations of motion for a physical system.
The Lagrangian density for a Dirac field is
The Lagrangian density for quantum chromodynamics is [1] [2] [3]
en.wikipedia.org /wiki/Lagrangian   (948 words)

  
 Lagrangian point - Education - Information - Educational Resources - Encyclopedia - Music
As seen in a frame of reference which rotates with the same period as the two co-orbiting bodies, the gravitational fields of two massive bodies combined with the centrifugal force are in balance at the Lagrangian points, allowing the third body to be stationary relative to the first two bodies.
In the more general case of elliptical orbits, there are no longer stationary points in the same sense, but the Lagrangian points constructed at each point in time as in the circular case form stationary elliptical orbits which are similar to the orbits of the massive bodies.
The first three Lagrangian points are stable only in the plane perpendicular to the line between the two bodies.
education.music.us /L/Lagrangian-point.htm   (1585 words)

  
 Constrained Optimization   (Site not responding. Last check: 2007-11-05)
The latter result in the theorem says that the Hessian of the Lagrangian evaluated at its stationary points is non-negative definite with respect to all vectors orthogonal to the gradient of the constraint.
Once insured real, the gradient of the Lagrangian with respect to the conjugate of the independent vector can be evaluated and the minimization procedure remains as before.
The Lagrangian is formed from the objective function and the real part of the usual constraint term.
cnx.org /content/m11223/latest   (1476 words)

  
 [No title]
A Lagrangian data assimilation method has been developed and applied to oceanographic models of increasing complexity and realism, including a quasi-geostropic model and two versions of the primitive equation Miami Isopycnic Ocean Model (MICOM) with 1.5 and multiple layers, respectively.
Comparison with different methods where the exact Lagrangian nature of the data is not considered, show the advantage of the present methodology (Fig.
The comparison is made as function of the number of drifters, using 2 basic parameters which characterize the time evolution of the error metric: the e-folding time scale (upper panel) and the residual error (lower panel).
www.rsmas.miami.edu /LAPCOD/research/2004c   (747 words)

  
 Reference on Lagrangian particle & trajectory modeling
P. Hurley and Physick W. A Lagrangian particle model of fumigation by breakdown of the nocturnal inversion.
Lagrangian stochastic analysis of flux-gradient relationships in the convective boundary layer.
Lagrangian particle simulation of tracer dispersion in the lee of a schematic two-dimensional hill.
users.frii.com /uliasz/modeling/ref/lpd_bib.htm   (2598 words)

  
 Wave Lagrangian   (Site not responding. Last check: 2007-11-05)
In this section the wave Lagrangian  for Alfvén waves is derived.
The orthogonality of the MHD eigenfunctions prevents the formation of a double sum over the perturbed waves present in the final volume integral by ensuring that all of the cross terms are zero.
This is the Lagrangian formulation of the wave equation describing shear Alfvén waves and is equivalent to equation (2.13).
www.rzg.mpg.de /~sip/thesis/node48.html   (436 words)

  
 Lagrangian Points
If the distance is just right--about 4 times the distance to the Moon or 1/100 the distance to the Sun--the spacecraft, too, will need just one year to go around the Sun, and will keep its position between the Sun and the Earth.
The sister-site From Stargazers to Starships discusses Lagrangian points in more detail than is done here, among other things deriving the distance of L1 (the derivation of L2 is almost identical) and also the equilibrium points L4 and L5.
A spacecraft placed there is more distant from the Sun and therefore should orbit it more slowly than the Earth; but the extra pull of the Earth adds up to the Sun's pull, and this allows the spacecraft to move faster and keep up with the Earth.
www-spof.gsfc.nasa.gov /Education/wlagran.html   (901 words)

  
 Rahul Zaveri - Research - Lagrangian Flight Planner   (Site not responding. Last check: 2007-11-05)
Some processes involving reactive trace gases and aerosols in the atmosphere are so complex that there may be no substitute for observing their rates in the actual atmosphere.
Although difficult to execute, such a Lagrangian measurement strategy can provide a much deeper insight into the chemical and meteorological processes occurring in an air parcel of interest than can be obtained by using other measurement strategies.
During the NAOPEX 2002 campaign, Rahul Zaveri, Carl Berkowitz, and John Hubbe conducted a nighttime Lagrangian experiment in the New England area using tetroons and the G-1 aircraft to study the interactions of aerosols and oxidants.
www.pnl.gov /atmos_sciences/raz/research/lagrangian-tools.html   (721 words)

  
 SPENDULAP, Lagrangian Dynamics; F. Ghorbel, J.B. Dabney   (Site not responding. Last check: 2007-11-05)
The Lagrangian formulation of dynamics is a useful alternative to the Newtonian formulation.
The first step in applying the Lagrangian formulation is to write the kinetic and potential energy in some generalized coordinate system.
On the other hand, the Newtonian approach yields the constraint forces as a by-product of the analysis, and it is often necessary to know the constraint forces.
dacnet.rice.edu /users/ghorbel/5.html   (235 words)

  
 Klein Bottle Problem and Unknottedness of Lagrangian Tori   (Site not responding. Last check: 2007-11-05)
First of all one may assume that we have a Lagrangian embedding into the complement of a projective line in the complex projective plane.
whose boundaries are geodesics on the Lagrangian eqipped with a flat metric, and
On the other hand, it also shows that the Lagrangian torus is isomorphic to one in the complement of
www.math.sunysb.edu /~klaus/research/researchplan_new/node6.html   (280 words)

  
 2 Lagrangian mechanics   (Site not responding. Last check: 2007-11-05)
In Lagrangian mechanics the equations of motion are written in the following universal form:
This equation is identical to the equation obtained from Lagrangian representation if f (q,t) is a conservative field, i.e.
According to 5 the equations of motion reduce to 11.
alamos.math.arizona.edu /~rychlik/557-dir/mechanics/node2.html   (214 words)

  
 GCSS ASTEX Lagrangian Case Specifications
The frame now accelerates relative to the surface of the earth, and the acceleration of the frame should be accounted for in the model momentum equations.
To ensure we are all in the same ballpark, note that the hourly sounding files all contain a measured value of downwelling LW flux at 700 mb (Austin and Bretherton 1995).
With the exception of June 19.4-19.75 during Lagrangian 2, during which there was cirrus cloud cover, these downwelling fluxes agree very well with clear air calculations based on temperature and moisture profiles taken from ECMWF analyses done for ASTEX (Austin and Bretherton 1995).
www.atmos.washington.edu /~breth/GCSS/ASTEX_lagr/ASTEX_spec.html   (1426 words)

  
 [No title]
Lagrangian submanifolds have classically played an important role in symplectic geometry.
From the point of view of existence theory for special lagrangian cycles, it has been shown that one can formulate a variational problem for volume and develop much of the necessary machinery (Schoen-Wolfson).
This workshop aims at exploring the new applications of lagrangians in symplectic and Kähler geometry, with particular emphasis on techniques for construction.
www.ipam.ucla.edu /programs/gls2003   (280 words)

  
 Lagrangian Support Vector Machines   (Site not responding. Last check: 2007-11-05)
An implicit Lagrangian for the dual of a simple reformulation of the standard quadratic program of a linear support vector machine is proposed.
This leads to the minimization of an unconstrained differentiable convex function in a space of dimensionality equal to the number of classified points.
A short MATLAB code is also given for nonlinear kernels and tested on a number of problems.
www.ai.mit.edu /projects/jmlr/papers/volume1/mangasarian01a/html   (237 words)

  
 Lagrangian Embeddings into   (Site not responding. Last check: 2007-11-05)
The Hamiltonian flow on it is parallel to the geodesic flow.
To this end it is hoped that computing symplectic field theoretic invariants could settle this issue.
Second, because the example of the Kleinbottle below suggests that the answer might be not that simple, since its invariants should not vanish altogether.
www.math.sunysb.edu /~klaus/research/researchplan_new/node5.html   (228 words)

  
 PUFF: A Lagrangian Trajectory Volcanic Ash Tracking Model   (Site not responding. Last check: 2007-11-05)
PUFF is an ash tracking model used by various agencies to assess volcanic ash hazard.
The model was developed to simulate the movement of airborne ash using forecast wind data sets.
PUFF tracks particles through a Lagrangian formulation of advection, fallout and turbulent dispersion through a random-walk technique.
pafc.arh.noaa.gov /puff   (80 words)

  
 HYbrid Single-Particle Lagrangian Integrated Trajectory Model
The HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) model is the newest version of a complete system for computing simple air parcel trajectories to complex dispersion and deposition simulations.
As a result of a joint effort between NOAA and Australia's Bureau of Meteorology, the model has recently been upgraded.
Kinematic and Isentropic Trajectories - Draxler, R.R. 1996, Boundary layer isentropic and kinematic trajectories duing the August 1993 North Atlantic Regional Experiment Intensive, J. Geophys.
www.arl.noaa.gov /ready/hysp_info.html   (951 words)

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