شروع کار گرانش سه بعدی و سیاه چاله ها

سلام

می خوام یک کتاب برای دوستانی که نسبیت عام رو نخوندم معرفی کنم که توی مراحل کار از نظر علمی عقب نباشند

Elementary General Relativity by Alan Macdonald

این کتاب خیلی ساده و مختصر و مفید به شما نسبت عام یاد می دهد و کل کتاب 100 صفحه است و 4 بخش دارد

1- flat spacetimes

2- curved spacetimes

3- spherically symmetric spacetimes

4- cosmological spacetimes

فصل اول کتاب که تقریبا نسبیت خاص است، دوستانی که می خواهند گرانش در سه بعد کار کنند کافی است دو فصل اول را بخواند و دوستانی که می خواهند سیاه چاله کار کنند کافی است که سه فصل اول را بخواند.

امیدوارم مرحله مقدماتی کار که خواندن شماست به سرعت تمام شود. دوستان هر سوالی داشتند بپرسند و با هم بحث کنند در وبلاگ تا مشکلات مفهومی ما در مرحله مقدماتی درباره نسبیت عام برطرف شود.

کتاب را از لینک زیر دانلود کنید

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&ved=0CD0QFjAC&url=http%3A%2F%2Ffaculty.luther.edu%2F~macdonal%2FEGR.pdf&ei=xEW_UY-2FZDxyAGIqIEo&usg=AFQjCNHMWBmv28QAC6v6-EP1Rq0Tua-MsA&sig2=LXEI_F-n7rBG5eNkgsJ2Og&bvm=bv.47883778,d.Yms

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http://s4.picofile.com/file/7800364622/black_holes.pdf.html

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Application of polyimides in nanotechnology as thin layer matrix for nanocomposites

Polyimides (PI) are a class of organic compounds containing imide bond in their molecule.
Aromatic polyimides are well-known polymers and due to the attractiveness of their
properties such as a low dielectric constant, high thermal stability, high chemical resistance,
high optical transmittance as well as very good mechanical properties. They are used in
opto- and microelectronics, as well as in nanotechnology as a matrix in the production of
nanocomposite layers (Francisko Raymo, 2007; Strunskus,Y and Grunze,M, 1994; Osvaldo
N. Oliveira et al, 2005; Mitchell Anthamatten et al., 2004; C.P. Wong, 1993). Nanocomposite
materials represent combinations of substances– polymers, chromophores, metals, etc. in
which one component is the matrix and the other one – the “guest”, embedded in the matrix
as nanosized particles. There is no chemicalinteraction occurring between the matrix and
the “guest”. The space volume between the individual molecules allows for the “guest”
molecules to be embedded in the matrix pores and a thickening of the layer achieved during
the following thermal process.
The high thermal and chemical stability of PI is interpreted by two factors:
(i)  the high resonance energy of the benzene rings due to delocalization of the π-electrons and the great number of resonance structures;
(ii)  strength of the imide bonds, resulting from the competitive n-πconjugation
between the carbonyl group and the non pair electron couple from the nitrogen
atom as well as from the conformation state of the 5- member imide ring. The lack of Baer’s angular torsion is due to the fact that all С- and N- atoms are in a sp2
hybrid state with valency angle of 120º and planar conformation of the ring.
Thermal destruction of the PI obtained from the precursors PMDA (pyromellitic
dianhydride) and ОDА(4,4’-oxydianiline) is only observed at temperature above 420-450 ºСthe mechanism studied by R. Ginsburg and J.R. Susko and proven with mass
spectrometry  (R. Ginsburg and J.R. Susko, 1984
Aromatic polyimides display attractive properties such as chemical resistance, thermal
stability and stability to photo-ageing. They havethe capacity to perform the matrix role in
the formation of nanocomposite layers with an embedded chromophore as “guest” and are
materials of good prospects for applying in contemporaryand future nanotechnology.

Polymer thin films, Abbas. A. Hashim

Field emission scanning electron microscope

Scanningelectron microscopes (SEMs) have been used by researchers since
1935 to examine micrometre scale structures and more often recently to
examine nanoscale structures . This is a versatile technique with which
relatively large samples can be visualized, dimensional measurements can
be taken and compositional analysis can be performed. The SEM works by
initially firing primary electrons at the sample to be imaged. Electrons are
dislodged from the atoms at the surface of the sample and are attracted to
a positively charged detector grid. These electrons are known as secondary
electrons. When a set pattern of primary electron beam scanning is used
over the surface, recording of the secondary electrons allows the surface
topology to be interpreted and displayed. Spatial resolution within a given
SEM depends on the primary electron beam spot size and the volume of
material with which the electrons interact. Under good conditions, such as
high accelerating voltage (e.g. 30 kV), well-aligned apertures, well-corrected
astigmatism, small spot size (small probe current) and no sample charging,
resolutions of 3 nm can typically be achieved. Conventionally, tungsten and
carbon elements were used in SEMs; to achieve longer gun lives, LaB6 elements
have been adopted more recently. Primary electrons that are bounced
back off the surface are known as back scattered electrons (BSE). The
energy of these electrons is directly related to the density of the atoms from which they are repelled and therefore their recording allows the variation of
surface composition to be visualized Afield emission cathode in the electron gun of
      an SEM provides narrower probing beams resulting in both improved spatial resolution
and less sample charging. Such systems are designated as field emission
scanning electron microscopes (FESEMs). In order to achieve this increased
electron focusing, a different gun design is required. In this design, electrons
are expelled by applying a high electric field very close to the filament tip.
The size and proximity of the electric field to the electron reservoir in the
filament controls the degree to which electrons tunnel out of the reservoir.
One type of field emission gun commonly used is known as the Schottky
in-lens thermal FESEM electron gun. Cold gun alternatives are available
for even finer FESEM resolution; however, these suffer rapid degradation
and can therefore lead to expensive operation due to relatively frequent
placement. The field emission guns have higher stability, can allow higher
current and hence provide a smaller spot size. Under good operating conditions,
 a typical FESEM resolution of 1nm is achievable. Elements that
add to improved operation and FESEM resolution include designs with a
beam booster to maintain high beam energy, an electromagnetic multihole
beam aperture changer, a magnetic field lens and a beam path that has been
designed to prevent electron beam crossover.