eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2004-12-26
28
2
197
204
10.22099/ijsts.2004.2850
2850
GREEN FUNCTION OF AXISYMMETRIC MAGNETOSTATICS
F. DINI
1
S. KHORASANI
2
R. AMROLLAHI
3
Department of Plasma Physics, Nuclear Fusion Research Center, P. O. Box 14155-1339, Amirabad, Tehran, I. R. of Iran
Department of Plasma Physics, Nuclear Fusion Research Center, P. O. Box 14155-1339, Amirabad, Tehran, I. R. of Iran
Faculty of Physics, Amir Kabir University of Technology, Hafez Ave., Tehran, I. R. of Iran
A simple new closed form of the Green function for axisymmetric magnetostatic problems<br />is found analytically in cylindrical coordinates. The result is verified by applying several examples.
http://ijsts.shirazu.ac.ir/article_2850_78f46ca37722cee176b3d5c36468644a.pdf
Magnetostatics
green functions
partial differential equations
electromagnetics
eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2004-12-26
28
2
205
210
10.22099/ijsts.2004.2851
2851
RING RESONATOR COUPLED M-Z ALL-OPTICAL SWITCH BY USING A PUMPED NONLINEAR DIRECTIONAL COUPLER
A. BANANEJ
1
C. F. Li
2
G. M. XU
3
Institute of Modern Optics, Department of Physics, Harbin Institute of Technology Harbin 150001, China
Institute of Modern Optics, Department of Physics, Harbin Institute of Technology
Institute of Modern Optics, Department of Physics, Harbin Institute of Technology
We propose a new ring resonator side-coupled M-Z interferometer all-optical switch through<br />the pumped nonlinear directional coupler. By controlling pump power P to lead the coupler reflectivity<br />r approaching to 1, the resonator finesse will be enhanced dramatically, and then the minimum<br />switching power in silica-based practice devices can be obtained. As a sample, we use a nonlinear<br />coupler made by two erbium-doped fibers, and launch a 514.5nm-pump light into one of the cores to<br />make the reflective- index difference between two cores. Based on the asymmetric-coupler theory, we<br />simulate the relationship between r and P , and show that the required pump power is only 0.8mW<br />for r →1 .
http://ijsts.shirazu.ac.ir/article_2851_e5f5dfd855e274020bf319426b241bba.pdf
All optical switches
Mach-Zehnder interferometer
switching power
ring resonator
directional
coupler
Erbium-doped fiber
nonlinear refractive index
eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2004-12-26
28
2
211
217
10.22099/ijsts.2004.2852
2852
THE STRONG LAW OF LARGE NUMBERS FOR PAIRWISE NEGATIVELY DEPENDENT RANDOM VARIABLES
H. R. NILI SANI
1
H. A. AZARNOOSH
2
A. BOZORGNIA
3
Department of Statistics, School of Mathematical Sciences, Ferdowsi University, Mashhad, I. R. of Iran
Department of Statistics, School of Mathematical Sciences, Ferdowsi University, Mashhad, I. R. of Iran
Department of Statistics, School of Mathematical Sciences, Ferdowsi University, Mashhad, I. R. of Iran
In this paper, strong laws of large numbers (SLLN) are obtained for the sums ƒ°=<br />n<br />i<br />i X<br />1<br />, under<br />certain conditions, where {X ,n . 1} n is a sequence of pairwise negatively dependent random variables.
http://ijsts.shirazu.ac.ir/article_2852_6771ec51729c273c4892533588694959.pdf
Strong law of large numbers
pairwise negatively dependent random variables
eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2004-12-26
28
2
219
226
10.22099/ijsts.2004.2872
2872
CONTROLLING CHAOS IN 2-DIMENSIONAL SYSTEMS
L. M. SAHA
1
G. H. ERJAEE
2
M. BUDHRAJA
3
Department of Mathematics, Zakir Husain College, University of Delhi, New Delhi – 110002, India
Mathematics Department, College of Science, Shiraz University, Shiraz, I. R. of Iran
Department of Mathematics, Shivaji College, University of Delhi, New Delhi, 110027, India
A chaos control method suggested by Erjaee has been reviewed. It has been shown that this<br />technique can be applied in various evolutionary systems of 2-dimensional types. The method has been<br />applied for cases of the Henon map, as well as Burger’s map. The limitations of the control technique<br />have also been discussed by considering the Standard Map and the Gumowski-Mira map. The results<br />obtained through numerical calculations are very interesting and significant. This technique has some<br />advantages over many other techniques of chaos control in discrete systems.
http://ijsts.shirazu.ac.ir/article_2872_3e4c93e9d7f22c0baf6faf6a1cb17373.pdf
asymptotic stability
control parameter
chaos
eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2004-12-26
28
2
227
234
10.22099/ijsts.2004.2873
2873
STUDY OF THE DISTORTED LAYER STRUCTURE OF SILICON WAFERS BY THE METHOD OF PLASMA-CHEMICAL ETCHING AFTER MECHANICAL MACHINING PROCESSES
H. BIDADI
1
S. SOBHANIAN
2
SH. HASANLI
3
M. MAZIDI
4
M. KARIMI
5
Faculty of physics, Tabriz University, Tabriz, I. R. of Iran, 51664
Faculty of physics, Tabriz University, Tabriz, I. R. of Iran, 51664
National Academy of Sciences, Azerbaijan Republic
Faculty of physics, Tabriz University, Tabriz, I. R. of Iran, 51664
Faculty of physics, Tabriz University, Tabriz, I. R. of Iran, 51664
In this experimental work, by using the method of plasma-chemical etching, we have dealt<br />with the causes of the creation of a distorted layer on the surface of silicon wafers during mechanical<br />machining processes, in addition, the elucidation of connections between the structure of this layer and<br />characteristic parameters of the mechanical strength of these wafers have been studied. Experimental<br />results obtained at room temperature show that after cutting and grinding processes, the mean value of<br />mechanical strength σ, which is apparently independent of the types of conductivity, is significantly<br />lower than its theoretical value. Analysis of the dependence of mechanical parameters on the time of<br />plasma-chemical etching indicates that the lower values obtained for the mechanical strength of silicon<br />wafers is basically due to the existence of a distorted layer and corresponding internal stresses created on<br />the surface of these wafers after mechanical machining. Plasma-chemical etching leads to an increase in<br />σ value. Dependency of σ on the etching time is qualitatively described by the microstructure of the<br />distorted layer and parameters of the micro relief surface of the wafers. Correlation between parameters<br />σ, H, K and the microstructure of the distorted layer allows us to suggest the method of plasma chemical<br />etching as a method of investigating the microstructure of the distorted layer after the mechanical<br />machining processes.
http://ijsts.shirazu.ac.ir/article_2873_cb44f197ef0ec90cfe9655a260ba8284.pdf
Mechanical properties
silicon wafers
cutting
grinding and etching
eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2004-12-26
28
2
235
256
10.22099/ijsts.2004.2874
2874
COUNTEREXAMPLES IN a−MINIMAL SETS
F. AYATOLLAH ZADEH SHIRAZI
1
M. SABBAGHAN
2
Department of Mathematics, Faculty of Science, Tehran University, Enghelab Ave., Tehran, I. R. of Iran
Department of Mathematics, Faculty of Science, Tehran University, Enghelab Ave., Tehran, I. R. of Iran
Several tables have been given due to a − minimal sets. Our main aim in this paper is to<br />complete these tables by employing several examples.
http://ijsts.shirazu.ac.ir/article_2874_13052c36b479587657673f3fd3003a4f.pdf
a − minimal set
Distal
enveloping semigroup
proximal relation
trasformation semigroup
eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2004-12-26
28
2
257
266
10.22099/ijsts.2004.2875
2875
IMPROVED MIT BAG MODEL WITH HYPER CENTRAL INTERACTING POTENTIAL
A. A. RAJABI
1
Department of physics, Shahrood University of Technology, P. O. Box 36155-316 Shahrood, I. R of Iran,
An improved MIT bag model with hyper central interactions is used to calculate the static<br />properties of hadrons containing u, d, s and c quarks. We present a theoretical approach to the internal<br />structure of three-body hyper central interacting quarks in a hadron, in which we take hadron as a bag.<br />We discuss a few of the results obtained using a six-dimension harmonic oscilator (h.o) potential, having<br />a two-body character, which turns out to be a hyper central confinement part. The other potential is sixdimensional,<br />which is attractive for small separation, originating from the color charge of hyper color<br />term. However the potential can easily be generalized in order to allow a systematic analysis. We<br />calculate the relativistic wave function for quarks in a scalar-vector hyper central potential, analytically.<br />Finally, vanishing the normal component of vector current at the surface of the baryon bag as a boundary<br />condition equivalent to confinement, results in the static properties and the strength of hyper Coulomb<br />like potential parameter. This depends on the mass parameters contrary to almost all previous versions.<br />The calculated static properties for baryon are better than in the uncorrected versions of the model.<br />PACS index 12.39 .Ba, 12.39. Ki, 12.39. Pn
http://ijsts.shirazu.ac.ir/article_2875_9facb82266e750ab197e43b975176778.pdf
Hyper central interaction
hadron
static properties
dirac equation
charge radius
magnetic
moment
eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2004-12-26
28
2
267
275
10.22099/ijsts.2004.2876
2876
DIRECT SYSTEM AND DIRECT LIMIT OF v H -MODULES
M. GHADIRI
mghadiri@yazduni.ac.ir
1
B. DAVVAZ
2
Department of Mathematics, Yazd University, Yazd, I. R. of Iran
Department of Mathematics, Yazd University, Yazd, I. R. of Iran
The largest class of algebraic hyper structures satisfying the module like axioms is the v H -<br />module. In this paper, we consider the category of v H -modules and prove that the direct limit always<br />exists in this category. Direct limits are defined by a universal property, and so are unique. The most<br />powerful tool in order to obtain a module from a given v H - module is the quotient out procedure. To use<br />this method we consider the fundamental equivalence relationε * , and then prove some of the results<br />about the connection between the fundamental modules, direct systems and direct limits.
http://ijsts.shirazu.ac.ir/article_2876_94edaedce6187b8b1a0698546845c448.pdf
H -ring
v H -module
direct system
direct limit
fundamental relation
fundamental module
eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2004-12-26
28
2
277
288
10.22099/ijsts.2004.2877
2877
ANALYSIS OF SPATIAL POINT PATTERNS BY KERNEL IDENTIFICATION
M. Q. VAHIDI-ASL
1
M. R. FAGHIHI
2
Department of Statistics, Shahid Beheshti University, Evin, Tehran, I. R. of Iran 19839
Department of Statistics, Shahid Beheshti University, Evin, Tehran, I. R. of Iran 19839
In the analysis of spatial point patterns, complete spatial randomness (CSR) hypothesis,<br />which is a restriction of a homogenous Poisson process to study region A, operates as a dividing<br />hypothesis between “regular” and “aggregated” patterns. Meanwhile, many alternatives to CSR in<br />aggregated patterns are extensions of homogenous Poisson processes themselves. Therefore, when the<br />CSR hypothesis is rejected, results related to Poisson processes may be used to formulate plausible<br />alternatives to CSR. In this paper, we propose a new statistic for testing CSR and then by applying it in<br />conjunction with a notion of kernels of a point pattern, we determine the “parents” of a Poisson cluster<br />process when the CSR hypothesis is rejected and a Neyman-Scott process is assumed for the point<br />pattern under alternative hypothesis. We have made power studies for our test statistic by simulation, and<br />have also surveyed the performance of our method on a certain point pattern. Finally, the whole method<br />is carried on certain real life data.
http://ijsts.shirazu.ac.ir/article_2877_5bd76b51ec7c1bd86de9a2a44109d41e.pdf
Spatial point patterns
complete spatial randomness
poisson processes
Neyman-Scott processes
cluster analysis
eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2004-12-26
28
2
289
298
10.22099/ijsts.2004.2878
2878
REAL GROUP ALGEBRAS
A. EBADIAN
a.ebadian@urmia.ac.ir
1
A. R. MEDGHALCHI
2
Current address: Department of Mathematics, Urmia University, I. R. of Iran
Faculty of Mathematics, Teacher Training University, Tehran, I. R. of Iran, 15614
In this paper we initiate the study of real group algebras and investigate some of its aspects.<br />Let L1 (G) be a group algebra of a locally compact group G,τ :G →G be a group homeomorphism<br />such that τ 2 =τοτ = 1, the identity map, and Lp (G,τ ) = { f ∈ Lp (G) : fοτ = f } ( p ≥ 1) . In this<br />paper, among other results, we clarify the structure of Lp (G,τ ) and characterize amenability of<br />L1 (G,τ ) and identify its multipliers.
http://ijsts.shirazu.ac.ir/article_2878_fd81bbe40553022c0d8890f0037844bb.pdf
Real Banach algebra
amenability
multiplier
derivation
group involution
eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2004-12-26
28
2
299
305
10.22099/ijsts.2004.2879
2879
THE INVERSE OF COVARIANCE MATRICES FOR THE ARMA (p, q) CLASS OF PROCESSES
R. CHINIPARDAZ
chinipardaz_r@scu.ac.ir,
1
T. F. COX
2
Department of Statistics, University of Shahid Chamran, Ahvaz, I. R. of Iran
Unilever Research Port Sunlight, Quarry Road East, Bebington, Wirral, CH633JW, UK
Analysis of time series data can involve the inversion of large covariance matrices. For the<br />class of ARMA (p, q) processes there are no exact explicit expressions for these inverses, except for the<br />MA (1) process. In practice, the sample covariance matrix can be very large and inversion can be<br />computationally time consuming and so approximate explicit expressions for the inverse are desirable.<br />This paper offers some of these approximations.
http://ijsts.shirazu.ac.ir/article_2879_e6dd3db8174e2c4874cb614f1a0869d6.pdf
ARMA processes
band matrix
covariance matrix