تبليغاتX
Learning English as a second language

Learning English as a second language

Learning English at english-step (یادگیری زبان انگلیسی در english-step)

Chaos theory and Strange attractor

 Mandelbrot Set    

   Polish-born French mathematician Benoit Mandelbrot coined the term “fractal” to describe complex geometric shapes that, when magnified, continue to resemble the shape’s larger structure. This property, in which the pattern of the whole repeats itself on smaller and smaller scales, is called self similarity. The fractal shown here, called the Mandelbrot set, is the graphical representation of a mathematical function.

 

Chaos theory

   Despite advances made in systems analysis, many systems remain beyond the reach of current mathematics. Chaos theory, a relatively new area of mathematics, concerns the analysis of unpredictable systems that are extremely sensitive to initial conditions. One important example of a chaotic system is climate. Global climate modeling is an area of mathematical research that seeks to develop models for predicting the weather, given accurate data from weather satellites orbiting Earth. The problem in developing such models arises not from lack of data but from the difficulty of modeling such a complex system (Earth’s atmosphere) with a small number of equations. In such models even a thousand equations may be considered small. The solution of these equations is very sensitive to changes in the initial conditions. The term initial conditions refers to all the measurements at the starting time. A tiny inaccuracy in a single measurement of a chaotic system—such as a temperature variation of a fraction of a degree—can produce large errors in solutions to the model’s equations and predictions.

Applications include the study of turbulent flow in fluids, irregularities in biological systems, population dynamics, chemical reactions, plasma physics, meteorology, the motions of groups and clusters of stars, transportation dynamics, and many other fields.

-------------------------------------------------------------------------------------------

Lorenz attractor (strange attractor)

(After Edward Lorenz, its discoverer) A region in the phase space of the solution to certain systems of (non-linear) differential equations. Under certain conditions, the motion of a particle described by such as system will neither converge to a steady state nor diverge to infinity, but will stay in a bounded but chaotically defined region. By chaotic, we mean that the particle's location, while definitely in the attractor, might as well be randomly placed there. That is, the particle appears to move randomly, and yet obeys a deeper order, since is never leaves the attractor.
Lorenz modelled the location of a particle moving subject to atmospheric forces and obtained a certain system of ordinary differential equations. When he solved the system numerically, he found that his particle moved wildly and apparently randomly. After a while, though, he found that while the momentary behaviour of the particle was chaotic, the general pattern of an attractor appeared. In his case, the pattern was the butterfly shaped attractor now known as the Lorenz attractor.
(1996-01-13)

Meteorologist Edward Lorenz tried to model climate in a series of equations during the 1960s. In doing so, he produced a chaotic system of three related differential equations, now known as a Lorenz attractor, or strange attractor. Through his models he discovered the sensitivity of chaotic systems to initial conditions, which he phrased in the question “Does the flap of a butterfly’s wings in Brazil set off a tornado in Texas?”

The Lorenz attractor is an example of a fractal, a pattern produced by applying a function repeatedly, much like pushing a button on a calculator over and over. The sequence {x, f(x), f(f(x)), f(f(f(x))), ...}, when graphed in two dimensions, gives rise to beautiful, complex geometric images such as the Mandelbrot set pictured in this article. These fractal images are named after Benoit Mandelbrot, a Polish-born French mathematician who developed fractal geometry and coined the word fractal. The interesting relationship among fractals, chaos, and unstable phenomena such as turbulence is the subject of a field called nonlinear dynamics.

+ نوشته شده در  Fri 9 Jan 2009ساعت 2:18 AM  توسط M.Torabi  | 

Essay 2

People using language only to convey information are usually indifferent to the sounds of the words and may feel frustrated by their connotations and multiple denotations. They would rather confine each word to a single, exact meaning. They use, one might say, a fraction of the word and throw away the rest. Poets, on the other hand, use as much of the word as possible. They are interested in connotation and use it to enrich and convey meaning. And they may rely on more than one denotation. Perhaps the purest form of practical language is scientific language. Scientists need a precise language to convey information precisely. The existence of multiple denotations and various overtones of meaning may interfere with this purpose. As a result of this, scientists have even devised special "language" such as the following:

                                                                SO2 + H2O = H2SO3

In such a statement the symbols are entirely unambiguous; they have been stripped of all connotations and of all denotations but one. The word sulfurous, if it occurred in poetry, might have all kinds of connotations: fire, smoke, brimstone, hell, damnation. But H2SO3 means one thing and one thing only: sulfurous acid.

The ambiguity and multiplicity of meanings possessed by words might be an obstacle to the scientist, but they are advantage for the poet who seeks richness of meaning. One resource for that is a multidimensional language using a multidimensional vocabulary, in which the dimensions of connotation and sound are added to the dimension of denotation.

The poet, we may say, plays on many-stringed instrument and sounds more than one note at a time.

The first task in reading poetry, therefore, as in reading any kind of literature, is to develop a sense of language, a feeling for words. One needs to become acquainted with their shape, their color, and their flavor. Two of the ways of doing this are extensive use of the dictionary and extensive reading.  

 

+ نوشته شده در  Wed 7 Jan 2009ساعت 10:5 PM  توسط M.Torabi  | 

Word history of dirge (تاریخچه کلمه نوحه در فرهنگ انگلیسی)

Dirge (نوحه)

Word History: The history of the word dirge illustrates how a word with neutral connotations, such as direct, can become emotionally charged because of a specialized use. The Latin word dīrige is a form of the verb dīrigere, “to direct, guide,” that is used in uttering commands. In the Office of the Dead dīrige is the first word in the opening of the antiphon for the first nocturn of Matins: “Dirige, Domine, Deus meus, in conspectu tuo viam meam,” “Direct, O Lord, my God, my way in thy sight.” The part of the Office of the Dead that begins with this antiphon was named Dīrige in Ecclesiastical Latin. This word with this meaning was borrowed into English as dirige, first recorded in a work possibly written before 1200. Dirige was then extended to refer to the chanting or reading of the Office of the Dead as part of a funeral or memorial service. In Middle English the word was shortened to dirge, although it was pronounced as two syllables. After the Middle Ages the word took on its more general senses of “a funeral hymn or lament” and “a mournful poem or musical composition,” and developed its one-syllable pronunciation.

+ نوشته شده در  Sun 4 Jan 2009ساعت 9:1 PM  توسط M.Torabi  |