Abstract: In this paper, the absorption and fluorescence
emission spectra of Yb:Y3Al5O12 (YAG)(25 at%) crystal as a disk
laser medium are measured at high temperature (300-450K). The
absorption and emission cross sections of Yb:YAG crystal are
determined using Reciprocity method. Temperature dependence of
941nm absorption cross section and 1031nm emission cross section
is extracted in the range of 300-450K. According to our experimental
results, an exponential temperature dependence between 300K and
450K is acquired for the 1031nm peak emission cross section and
also for 941nm peak absorption cross section of Yb:YAG crystal.
These results could be used for simulation and design of high power
highly doped Yb:YAG thin disk lasers.
Abstract: Calculations of energy efficiency of several AACbased
building envelopes under different climatic conditions are
presented. As thermal insulating materials, expanded polystyrene and
hydrophobic and hydrophilic mineral wools are assumed. The
computations are accomplished using computer code HEMOT
developed at Department of Materials Engineering, Faculty of Civil
Engineering at the Czech Technical University in Prague. The
climatic data of Athens, Kazan, Oslo, Prague and Reykjavík are
obtained using METEONORM software.
Abstract: Recognizing human action from videos is an active
field of research in computer vision and pattern recognition. Human
activity recognition has many potential applications such as video
surveillance, human machine interaction, sport videos retrieval and
robot navigation. Actually, local descriptors and bag of visuals words
models achieve state-of-the-art performance for human action
recognition. The main challenge in features description is how to
represent efficiently the local motion information. Most of the
previous works focus on the extension of 2D local descriptors on 3D
ones to describe local information around every interest point. In this
paper, we propose a new spatio-temporal descriptor based on a spacetime
description of moving points. Our description is focused on an
Accordion representation of video which is well-suited to recognize
human action from 2D local descriptors without the need to 3D
extensions. We use the bag of words approach to represent videos.
We quantify 2D local descriptor describing both temporal and spatial
features with a good compromise between computational complexity
and action recognition rates. We have reached impressive results on
publicly available action data set
Abstract: Tehran, one of the heavily-populated capitals, is
severely suffering from increasing air pollution. To show a
documented trend of such pollutants during last years, plane tree
species (Platanus orientalis) were suited to be studied as indicators,
for the species have been planted throughout the city many years
ago. Two areas (Saadatabad and Narmak districts) allotting different
contents of crowed and highly-traffic routs but the same ecological
characteristics were selected. Twelve sample individuals were cored
twice perpendicularly in each area. Tree-rings of each core were
measured by a binocular microscope and separated annually for the
last 25 years. Two heavy metals including Cd and Pb accompanied
by a mineral element (Ca) were analyzed using Hatch method. Treerings
analysis of the two areas showed different groups in term of
physiologically ability as the growths were plunged during the last
10 years in Saadatabad district and showed a slight decrease in the
same period for another studying area. In direct contrast to
decreasing growth trend in Saadatabad, all three mentioned elements
increased sharply during last 25 years in the same area. When it came
to Narmak district, the trend was completely different with
Saadatabad. There were some fluctuations in absorbing trace
elements like tree-rings widths were, yet calcium showed an upward
trend all the last 25 years. The results of the study proved the
possibility of using tree species of each region to monitor its air
pollution trends of the past, hence to depict a pollution assessment of
a populated city for last years and then to make appropriate decisions
for the future as it is well-known what the trend is. On the other
hand, risen values of calcium (as the stress-indicator element)
accompanied by increased trace elements suggests non-sustainable
state of the trees.
Abstract: Geosynthetics have proved to be suitable for
reinforced soil retaining walls. Based on the increasing uses of
geosynthetic reinforced soil systems in the regions, which bear
frequent earthquakes, the study of dynamic behavior of structures
seems necessary. Determining the reinforcement forces is; therefore,
one of the most important and main points of discussions in
designing retaining walls, by which we prevent from conservative
planning. Thus, this paper intended to investigate the effects of such
parameters as wall height, acceleration type, vertical spacing of
reinforcement, type of reinforcement and soil type on forces and
deformation through numerical modeling of the geosynthetic
reinforced soil retaining walls (GRSRW) under dynamic loading with
finite difference method by using FLAC. The findings indicate rather
positive results with each parameter.
Abstract: This paper studies mechanical buckling of
functionally graded beams subjected to axial compressive load that is
simply supported at both ends lies on a continuous elastic foundation.
The displacement field of beam is assumed based on Engesser-Timoshenko beam theory. Applying the Hamilton's principle, the
equilibrium equation is established. The influences of dimensionless geometrical parameter, functionally graded index and foundation
coefficient on the critical buckling load of beam are presented. To investigate the accuracy of the present analysis, a compression study
is carried out with a known data.
Abstract: In this work, we study elliptic divisibility sequences
over finite fields. Morgan Ward in [14], [15] gave arithmetic theory
of elliptic divisibility sequences and formulas for elliptic divisibility
sequences with rank two over finite field Fp. We study elliptic
divisibility sequences with rank three, four and five over a finite field
Fp, where p > 3 is a prime and give general terms of these sequences
and then we determine elliptic and singular curves associated with
these sequences.
Abstract: Design of a constant chord propeller is presented in
this paper in order to reduce propeller-s design procedure-s costs. The
design process was based on Lock and Goldstein-s techniques of
propeller design and analysis. In order to calculate optimum chord of
propeller, chord of a referential element is generalized as whole
blades chord. The design outcome which named CS-X-1 is modeled
& analyzed by CFD methods using K-ε: R.N.G turbulence model.
Convergence of results of two codes proved that outcome results of
design process are reliable. Design result is a two-blade propeller
with a total diameter of 1.1 meter, radial velocity of 3000 R.P.M,
efficiency above .75 and power coefficient near 1.05.
Abstract: The work describes the use of a synthetic transmit
aperture (STA) with a single element transmitting and all elements
receiving in medical ultrasound imaging. STA technique is a novel
approach to today-s commercial systems, where an image is acquired
sequentially one image line at a time that puts a strict limit on the
frame rate and the amount of data needed for high image quality. The
STA imaging allows to acquire data simultaneously from all
directions over a number of emissions, and the full image can be
reconstructed.
In experiments a 32-element linear transducer array with 0.48 mm
inter-element spacing was used. Single element transmission aperture
was used to generate a spherical wave covering the full image region.
The 2D ultrasound images of wire phantom are presented obtained
using the STA and commercial ultrasound scanner Antares to
demonstrate the benefits of the SA imaging.
Abstract: Iris pattern is an important biological feature of human body; it becomes very hot topic in both research and practical applications. In this paper, an algorithm is proposed for iris recognition and a simple, efficient and fast method is introduced to extract a set of discriminatory features using first order gradient operator applied on grayscale images. The gradient based features are robust, up to certain extents, against the variations may occur in contrast or brightness of iris image samples; the variations are mostly occur due lightening differences and camera changes. At first, the iris region is located, after that it is remapped to a rectangular area of size 360x60 pixels. Also, a new method is proposed for detecting eyelash and eyelid points; it depends on making image statistical analysis, to mark the eyelash and eyelid as a noise points. In order to cover the features localization (variation), the rectangular iris image is partitioned into N overlapped sub-images (blocks); then from each block a set of different average directional gradient densities values is calculated to be used as texture features vector. The applied gradient operators are taken along the horizontal, vertical and diagonal directions. The low order norms of gradient components were used to establish the feature vector. Euclidean distance based classifier was used as a matching metric for determining the degree of similarity between the features vector extracted from the tested iris image and template features vectors stored in the database. Experimental tests were performed using 2639 iris images from CASIA V4-Interival database, the attained recognition accuracy has reached up to 99.92%.
Abstract: In recent years, there have been attempts to store
natural gas in adsorptive form. This is called adsorptive natural gas,
or ANG. The problem with this technology is the low sorption
capacity. The purpose is to achieve compressed natural gas (CNG)
capacity of 230 V/V. Further research is required to achieve such
target. Several research studies have been performed with this target;
through either the modification or development of new sorbents or
the optimization of the operation sorption process itself. In this work,
storage of methane on molecular sieves 5A and 13X was studied on
dry basis, and on wet basis to certain extent. The temperature and the
pressure dynamics were investigated. The results indicated that
regardless of the charge pressure, the time for the peak temperature
during the methane charge process is always the same. This can be
used as a characteristic of the adsorbent. The total achieved
deliveries using molecular sieves were much lower than that of
activated carbons; 53.0 V/V for the case of 13X molecular sieves and
43 V/V for the case of 5A molecular sieves, both at 2oC and 4 MPa
(580 psi). Investigation of charge pressure dynamic using wet
molecular sieves at 2oC and a mass ratio of 0.5, revealed slowness of
the process and unexpected behavior.
Abstract: Persian (Farsi) script is totally cursive and each character is written in several different forms depending on its former and later characters in the word. These complexities make automatic handwriting recognition of Persian a very hard problem and there are few contributions trying to work it out. This paper presents a novel practical approach to online recognition of Persian handwriting which is based on representation of inputs and patterns with very simple visual features and comparison of these simple terms. This recognition approach is tested over a set of Persian words and the results have been quite acceptable when the possible words where unknown and they were almost all correct in cases that the words where chosen from a prespecified list.
Abstract: The objective of this study is to investigate the effect of adding coal to obtain insulating ceramic product. The preparation of mixtures is achieved with 04 types of different masse compositions, consisting of gray and yellow clay, and coal. Analyses are performed on local raw materials by adding coal as additive. The coal content varies from 5 to 20 % in weight by varying the size of coal particles ranging from 0.25mm to 1.60mm.
Initially, each natural moisture content of a raw material has been determined at the temperature of 105°C in a laboratory oven. The Influence of low-coal content on absorption, the apparent density, the contraction and the resistance during compression have been evaluated. The experimental results showed that the optimized composition could be obtained by adding 10% by weight of coal leading thus to insulating ceramic products with water absorption, a density and resistance to compression of 9.40 %, 1.88 g/cm3, 35.46 MPa, respectively. The results show that coal, when mixed with traditional raw materials, offers the conditions to be used as an additive in the production of lightweight ceramic products.
Abstract: The purpose of this study was to investigate the effects of computer–based instructional designs, namely modality and redundancy principles on the attitude and learning of music theory among primary pupils of different Music Intelligence levels. The lesson of music theory was developed in three different modes, audio and image (AI), text with image (TI) and audio with image and text (AIT). The independent variables were the three modes of courseware. The moderator variable was music intelligence. The dependent variables were the post test score. ANOVA was used to determine the significant differences of the pretest scores among the three groups. Analyses of covariance (ANCOVA) and Post hoc were carried out to examine the main effects as well as the interaction effects of the independent variables on the dependent variables. High music intelligence pupils performed significantly better than low music intelligence pupils in all the three treatment modes. The AI mode was found to help pupils with low music intelligence significantly more than the TI and AIT modes.
Abstract: Among various testing methodologies, Built-in Self-
Test (BIST) is recognized as a low cost, effective paradigm. Also,
full adders are one of the basic building blocks of most arithmetic
circuits in all processing units. In this paper, an optimized testable 2-
bit full adder as a test building block is proposed. Then, a BIST
procedure is introduced to scale up the building block and to generate
a self testable n-bit full adders. The target design can achieve 100%
fault coverage using insignificant amount of hardware redundancy.
Moreover, Overall test time is reduced by utilizing polymorphic
gates and also by testing full adder building blocks in parallel.
Abstract: Linear two-point boundary value problems of order
two are solved using cubic trigonometric B-spline interpolation
method (CTBIM). Cubic trigonometric B-spline is a piecewise
function consisting of trigonometric equations. This method is tested
on some problems and the results are compared with cubic B-spline
interpolation method (CBIM) from the literature. CTBIM is found to
approximate the solution slightly more accurately than CBIM if the
problems are trigonometric.
Abstract: In this paper, we define distance partition of vertex set of a graph G with reference to a vertex in it and with the help of the same, a graph with metric dimension two (i.e. β (G) = 2 ) is characterized. In the process, we develop a polynomial time algorithm that verifies if the metric dimension of a given graph G is two. The same algorithm explores all metric bases of graph G whenever β (G) = 2 . We also find a bound for cardinality of any distance partite set with reference to a given vertex, when ever β (G) = 2 . Also, in a graph G with β (G) = 2 , a bound for cardinality of any distance partite set as well as a bound for number of vertices in any sub graph H of G is obtained in terms of diam H .
Abstract: Extraction of Fe(III) from aqueous solution using Trin-
butyl Phosphate (TBP) as carrier needs a highly acidic medium
(>6N) as it favours formation of chelating complex FeCl3.TBP.
Similarly, stripping of Iron(III) from loaded organic solvents requires
neutral pH or alkaline medium to dissociate the same complex. It is
observed that TBP co-extracts acids along with metal, which causes
reversal of driving force of extraction and iron(III) is re-extracted
back from the strip phase into the feed phase during Liquid Emulsion
Membrane (LEM) pertraction. Therefore, rate of extraction of
different mineral acids (HCl, HNO3, H2SO4) using TBP with and
without presence of metal Fe(III) was examined. It is revealed that in
presence of metal acid extraction is enhanced. Determination of mass
transfer coefficient of both acid and metal extraction was performed
by using Bulk Liquid Membrane (BLM). The average mass transfer
coefficient was obtained by fitting the derived model equation with
experimentally obtained data. The mass transfer coefficient of the
mineral acid extraction is in the order of kHNO3 = 3.3x10-6m/s > kHCl =
6.05x10-7m/s > kH2SO4 = 1.85x10-7m/s. The distribution equilibria of
the above mentioned acids between aqueous feed solution and a
solution of tri-n-butyl-phosphate (TBP) in organic solvents have been
investigated. The stoichiometry of acid extraction reveals the
formation of TBP.2HCl, HNO3.2TBP, and TBP.H2SO4 complexes.
Moreover, extraction of Iron(III) by TBP in HCl aqueous solution
forms complex FeCl3.TBP.2HCl while in HNO3 medium forms
complex 3FeCl3.TBP.2HNO3
Abstract: This paper presents investigation effects of a sharp edged gust on aeroelastic behavior and time-domain response of a typical section model using Jones approximate aerodynamics for pure plunging motion. Flutter analysis has been done by using p and p-k methods developed for presented finite-state aerodynamic model for a typical section model (airfoil). Introduction of gust analysis as a linear set of ordinary differential equations in a simplified procedure has been carried out by using transformation into an eigenvalue problem.
Abstract: Reduced switching loss favours Pulse Skipping
Modulation mode of switching dc-to-dc converters at light loads.
Under certain conditions the converter operates in discontinuous
conduction mode (DCM). Inductor current starts from zero in each
switching cycle as the switching frequency is constant and not
adequately high. A DC-to-DC buck converter is modelled and
simulated in this paper under DCM. Effect of ESR of the filter
capacitor in input current frequency components is studied. The
converter is studied for its operation under input voltage and load
variation. The operating frequency is selected to be close to and
above audio range.