Abstract: Parameters of flow are calculated in vaneless diffusers
with relative width 0,014–0,10. Inlet angles of flow and similarity
criteria were varied. There is information on flow separation,
boundary layer development, configuration of streamlines.
Polytrophic efficiency, loss coefficient and recovery coefficient are
used to compare effectiveness of diffusers. The sample of
optimization of narrow diffuser with conical walls is presented. Three
wide diffusers with narrowing walls are compared. The work is made
in the R&D laboratory “Gas dynamics of turbo machines” of the TU
SPb.
Abstract: There is an evident trend to elevate pressure ratio of a
single stage of a turbo compressors - axial compressors in particular.
Whilst there was an opinion recently that a pressure ratio 1,9 was a
reasonable limit, later appeared information on successful modeling
tested of stages with pressure ratio up to 2,8. The authors recon that
lack of information on high pressure stages makes actual a study of
rational choice of design parameters before high supersonic flow
problems solving. The computer program of an engineering type was
developed. Below is presented a sample of its application to study
possible parameters of the impeller of the stage with pressure ratio
3,0. Influence of two main design parameters on expected efficiency,
periphery blade speed and flow structure is demonstrated. The results
had lead to choose a variant for further analysis and improvement by
CFD methods.
Abstract: The mechanics of rip currents are complex, involving
interactions between waves, currents, water levels and the bathymetry,
that present particular challenges for numerical models. Here,
the effects of a grid-spacing dependent horizontal mixing on the
wave-current interactions are studied. Near the shore, wave rays
diverge from channels towards bar crests because of refraction by
topography and currents, in a way that depends on the rip current
intensity which is itself modulated by the horizontal mixing. At
low resolution with the grid-spacing dependent horizontal mixing,
the wave motion is the same for both coupling modes because the
wave deviation by the currents is weak. In high resolution case,
however, classical results are found with the stabilizing effect of
the flow by feedback of waves on currents. Lastly, wave-current
interactions and the horizontal mixing strongly affect the intensity
of the three-dimensional rip velocity.
Abstract: It has experimentally been proved that the
performance of compression ignition (C.I.) engine is spray
characteristics related. In modern diesel engine the spray formation
and the eventual combustion process are the vital processes that offer
more challenges towards enhancing the engine performance. In the
present work the numerical simulation has been carried out for
evaporating diesel sprays using Fluent software. For computational
fluid dynamics simulation “Meshing” is done using Gambit software
before transmitting it into Fluent. The simulation is carried out using
hot bomb conditions under varying chamber conditions such as gas
pressure, nozzle diameter and fuel injection pressure. For comparison
purpose, the numerical simulations the chamber conditions were kept
the same as that of the experimental data. At varying chamber
conditions the spray penetration rates are compared with the existing
experimental results.
Abstract: Conventional educational practices, do not offer all
the required skills for teachers to successfully survive in today’s
workplace. Due to poor professional training, a big gap exists across
the curriculum plan and the teacher practices in the classroom. As
such, raising the quality of teaching through ICT-enabled training and
professional development of teachers should be an urgent priority.
‘Mobile Learning’, in that vein, is an increasingly growing field of
educational research and practice across schools and work places. In
this paper, we propose a novel Mobile learning system that allows the
users to learn through an intelligent mobile learning in cooperatively
every-time and every-where. The system will reduce the training cost
and increase consistency, efficiency, and data reliability. To establish
that our system will display neither functional nor performance
failure, the evaluation strategy is based on formal observation of
users interacting with system followed by questionnaires and
structured interviews.
Abstract: Bacterial strains capable of degradation of malathion
from the domestic sewage were isolated by an enrichment culture
technique. Three bacterial strains were screened and identified as
Acinetobacter baumannii (AFA), Pseudomonas aeruginosa (PS1),
and Pseudomonas mendocina (PS2) based on morphological,
biochemical identification and 16S rRNA sequence analysis.
Acinetobacter baumannii AFA was the most efficient malathion
degrading bacterium, so used for further biodegradation study. AFA
was able to grow in mineral salt medium (MSM) supplemented with
malathion (100 mg/l) as a sole carbon source, and within 14 days,
84% of the initial dose was degraded by the isolate measured by high
performance liquid chromatography. Strain AFA could also degrade
other organophosphorus compounds including diazinon, chlorpyrifos
and fenitrothion. The effect of different culture conditions on the
degradation of malathion like inoculum density, other carbon or
nitrogen sources, temperature and shaking were examined.
Degradation of malathion and bacterial cell growth were accelerated
when culture media were supplemented with yeast extract, glucose
and citrate. The optimum conditions for malathion degradation by
strain AFA were; an inoculum density of 1.5x 10^12CFU/ml at 30°C
with shaking. A specific polymerase chain reaction primers were
designed manually using multiple sequence alignment of the
corresponding carboxylesterase enzymes of Acinetobacter species.
Sequencing result of amplified PCR product and phylogenetic
analysis showed low degree of homology with the other
carboxylesterase enzymes of Acinetobacter strains, so we suggested
that this enzyme is a novel esterase enzyme. Isolated bacterial strains
may have potential role for use in bioremediation of malathion
contaminated.
Abstract: This study examines several critical dimensions of eservice
quality overlooked in the existing literature and proposes a
model and instrument framework for measuring customer perceived
e-service quality in the banking sector. The initial design was derived
from a pool of instrument dimensions and their items from the
existing literature review by content analysis. Based on focused
group discussion, nine dimensions were extracted. An exploratory
factor analysis approach was applied to data from a survey of 323
respondents. The instrument has been designed specifically for the
banking sector. Research data was collected from bank customers
who use electronic banking in a developing economy. A nine-factor
instrument has been proposed to measure the e-service quality. The
instrument has been checked for reliability. The validity and sample
place limited the applicability of the instrument across economies and
service categories. Future research must be conducted to check the
validity. This instrument can help bankers in developing economies
like India to measure the e-service quality and make improvements.
The present study offers a systematic procedure that provides insights
on to the conceptual and empirical comprehension of customer
perceived e-service quality and its constituents.
Abstract: A new method for determining the distribution of
birefringence and linear dichroism in optical polymer materials is
presented. The method is based on the use of polarizationholographic
diffraction grating that forms an orthogonal circular basis
in the process of diffraction of probing laser beam on the grating. The
intensities ratio of the orders of diffraction on this grating enables the
value of birefringence and linear dichroism in the sample to be
determined. The distribution of birefringence in the sample is
determined by scanning with a circularly polarized beam with a
wavelength far from the absorption band of the material. If the
scanning is carried out by probing beam with the wavelength near to
a maximum of the absorption band of the chromophore then the
distribution of linear dichroism can be determined. An appropriate
theoretical model of this method is presented. A laboratory setup was
created for the proposed method. An optical scheme of the laboratory
setup is presented. The results of measurement in polymer films with
two-dimensional gradient distribution of birefringence and linear
dichroism are discussed.
Abstract: Equal channel angular pressing (ECAP) of
commercial Al-Mg-Si alloy was conducted using two strain rates.
The ECAP processing was conducted at room temperature and at
250°C. Route A was adopted up to a total number of four passes in
the present work. Structural evolution of the aluminum alloy discs
was investigated before and after ECAP processing using optical
microscopy (OM). Following ECAP, simple compression tests and
Vicker’s hardness were performed. OM micrographs showed that, the
average grain size of the as-received Al-Mg-Si disc tends to be larger
than the size of the ECAP processed discs. Moreover, significant
difference in the grain morphologies of the as-received and processed
discs was observed. Intensity of deformation was observed via the
alignment of the Al-Mg-Si consolidated particles (grains) in the
direction of shear, which increased with increasing the number of
passes via ECAP. Increasing the number of passes up to 4 resulted in
increasing the grains aspect ratio up to ~5. It was found that the
pressing temperature has a significant influence on the
microstructure, Hv-values, and compressive strength of the processed
discs. Hardness measurements demonstrated that 1-pass resulted in
increase of Hv-value by 42% compared to that of the as-received
alloy. 4-passes of ECAP processing resulted in additional increase in
the Hv-value. A similar trend was observed for the yield and
compressive strength. Experimental data of the Hv-values
demonstrated that there is a lack of any significant dependence on the
processing strain rate.
Abstract: Compositions of different molar ratios of
polymethylmethacrylate-co-methacrylic acid (PMMA-co-MAA)
were synthesized via free-radical polymerization. Polymer coated
surfaces have been produced on silicon wafers. Coated samples were
analyzed by atomic force microscopy (AFM). The results have shown
that the roughness of the surfaces have increased by increasing the
molar ratio of monomer methacrylic acid (MAA). This study reveals
that the gradual increase in surface roughness is due to the fact that
carboxylic functional groups have been generated by MAA segments.
Such surfaces can be desirable platforms for fabrication of the
biosensors for detection of the viruses and diseases.
Abstract: Food is widely packaged with plastic materials to
prevent microbial contamination and spoilage. Ionizing radiation is
widely used to sterilize the food-packaging materials. Sterilization by
γ-radiation causes degradation such as embrittlement, stiffening,
softening, discoloration, odour generation, and decrease in molecular
weight. Many antioxidants can prevent γ-degradation but most of
them are toxic. The migration of antioxidants to its environment
gives rise to major concerns in case of food packaging plastics. In
this attempt, we have aimed to utilize synergistic mixtures of
stabilizers which are approved for food-contact applications.
Ethylene-propylene-diene terpolymer has been melt-mixed with
hindered amine stabilizers (HAS), phenolic antioxidants and organophosphites
(hydroperoxide decomposer). Results were discussed by
comparing the stabilizing efficiency of mixtures with and without
phenol system. Among phenol containing systems where we mostly
observed discoloration due to the oxidation of hindered phenol, the
combination of secondary HAS, tertiary HAS, organo-phosphite and
hindered phenol exhibited improved stabilization efficiency than
single or binary additive systems. The mixture of secondary HAS and
tertiary HAS, has shown antagonistic effect of stabilization.
However, the combination of organo-phosphite with secondary HAS,
tertiary HAS and phenol antioxidants have been found to give
synergistic even at higher doses of Gamma-irradiation. The effects
have been explained through the interaction between the stabilizers.
After γ-irradiation, the consumption of oligomeric stabilizer
significantly depends on the components of stabilization mixture. The
effect of the organo-phosphite antioxidant on the overall stability has
been discussed.
Abstract: Liver disorders are one of the major problems of the
world. Despite its frequent occurrence, high morbidity and high
mortality, its medical management is currently inadequate. This study
was designed to evaluate the hepatoprotective effect of saponin
extract of the root of Garcinia kola on the integrity of the liver of
paracetamol induced wistar albino rats. Twenty five (25) male adult
wistar albino rats were divided into five (5) groups. Group I was the
Control group that received distilled water only, group II was the
negative control that received 2 g/kg of paracetamol on the 13th day,
and group III, IV and V were pre-treated with 100, 200 and
400mg/kg of the saponin extract before inducing the liver damage on
the 13th day with 2 g/kg of paracetamol. Twenty four (24) h after
administration, the rats were sacrificed and blood samples were
collected. The serum Alanine Transaminase (ALT), Aspartate
Transaminase (AST), Alkaline Phosphatase (ALP) activities,
Bilirubin and conjugated bilirubin, glucose and protein
concentrations were evaluated. The liver was fixed immediately in
Formalin and was processed and stained in Haematoxylin and Eosin
(H&E). Administration of saponin extract from the root of Garcinia
kola significantly decreased paracetamol induced elevated enzymes
in the test group. Also histological observations showed that saponin
extract of the root of Garcinia kola exhibited a significant liver
protection against the toxicant as evident by the cells trying to return
to normal. Saponin extract from the root of Garcinia kola indicated a
protection of structural integrity of the hepatocytic cell membrane
and regeneration of the damaged liver.
Abstract: Content-based image retrieval (CBIR) uses the
contents of images to characterize and contact the images. This paper
focus on retrieving the image by separating images into its three color
mechanism R, G and B and for that Discrete Wavelet Transformation
is applied. Then Wavelet based Generalized Gaussian Density (GGD)
is practical which is used for modeling the coefficients from the
wavelet transforms. After that it is agreed to Histogram of Oriented
Gradient (HOG) for extracting its characteristic vectors with Relevant
Feedback technique is used. The performance of this approach is
calculated by exactness and it confirms that this method is wellorganized
for image retrieval.
Abstract: For cycling, the analysis of the pedal force is one of the
important factors in the study of exercise ability assessment and
overuse injuries. In past studies, a two-axis measurement sensor was
used at the sagittal plane to measure the force only in the anterior,
posterior, and vertical directions and to analyze the loss of force and
the injury on the frontal plane due to the forces in the right and left
directions. In this study, which is a basic study on diverse analyses of
the pedal force that consider the forces on the sagittal plane and the
frontal plane, a three-axis pedal force measurement sensor was
developed to measure the anterior-posterior (Fx), medio-lateral (Fz),
and vertical (Fy) forces. The sensor was fabricated with a size and
shape similar to those of the general flat pedal, and had a 550g weight
that allowed smooth pedaling. Its measurement range was ±1000 N for
Fx and Fz and ±2000 N for Fy, and its non-linearity, hysteresis, and
repeatability were approximately 0.5%. The data were sampled at
1000 Hz using a signal collector. To use the developed sensor, the
pedaling efficiency (index of efficiency, IE) and the range of left and
right (medio-lateral, ML) forces were measured with two seat heights
(low and high). The results of the measurement showed that the IE was
higher and the force range in the ML direction was lower with the high
position than with the low position. The developed measurement
sensor and its application results will be useful in understanding and
explaining the complicated pedaling technique, and will enable
diverse kinematic analyses of the pedal force on the sagittal plane and
the frontal plane.
Abstract: This paper investigates the activity of the rectus
femoris (RF) and biceps femoris (BF) in healthy subjects during salat
(prostration) and specific exercise (squat exercise) using
electromyography (EMG). A group of undergraduates aged between
19 to 25 years voluntarily participated in this study. The myoelectric
activity of the muscles were recorded and analyzed. The finding
indicated that there were contractions of the muscles during the salat
and exercise with almost same EMG’s level. From the result,
Wilcoxon’s Rank Sum test showed significant difference between
prostration and squat exercise (p
Abstract: The transition period of Kosovo society brought
fundamental changes in all the spheres of organizing life. This was
the period when also in the cultural tradition the biggest movement
and an emerging from ‘isolation’ or from the ‘shell’ occurred.
Transformation of the traditional and embracing of the modern began
here. The same was experienced and is currently being experienced
also by Gjakova and its surrounding which is historically renowned
for its great tradition and culture.
The population of this region is actually facing a transition from
the traditional system into the modern one and quite often with huge
leaps.
These ‘movements’ or ‘evolutions’ of the society of this region,
besides the numerous positive things it ‘harvested’, also brought
things that do not at all correspond with their tradition as well as new
criminal occurrences which in the past were not present in this area.
Furthermore, some of the ‘new’ behaviors that are embraced from
other ‘cultures’ and ‘civilizations’, and which are often exceeded, are
quite perturbing. The security situation is also worrying, particularly
following the appearance of some new criminal occurrences.
Therefore, with this research paper we will strive to analyze the
new cultural “intersections” as well as the nature of the origin of
some new very worrying criminal occurrences. We will present there
also some factors inciting into these occurrences, which were
confessed by the persons involved in these criminal occurrences and
who come from this very region.
Abstract: We present a solution to the Maxmin u/E parameters
estimation problem of possibility distributions in m-dimensional
case. Our method is based on geometrical approach, where minimal
area enclosing ellipsoid is constructed around the sample. Also we
demonstrate that one can improve results of well-known algorithms
in fuzzy model identification task using Maxmin u/E parameters
estimation.
Abstract: This paper focuses on the assessment of the air
pollution and morbidity relationship in Tunisia. Air pollution is
measured by ozone air concentration and the morbidity is measured
by the number of respiratory-related restricted activity days during
the 2-week period prior to the interview. Socioeconomic data are also
collected in order to adjust for any confounding covariates. Our
sample is composed by 407 Tunisian respondents; 44.7% are women,
the average age is 35.2, near 69% are living in a house built after
1980, and 27.8% have reported at least one day of respiratory-related
restricted activity. The model consists on the regression of the
number of respiratory-related restricted activity days on the air
quality measure and the socioeconomic covariates. In order to correct
for zero-inflation and heterogeneity, we estimate several models
(Poisson, negative binomial, zero inflated Poisson, Poisson hurdle,
negative binomial hurdle and finite mixture Poisson models).
Bootstrapping and post-stratification techniques are used in order to
correct for any sample bias. According to the Akaike information
criteria, the hurdle negative binomial model has the greatest goodness
of fit. The main result indicates that, after adjusting for
socioeconomic data, the ozone concentration increases the probability
of positive number of restricted activity days.
Abstract: In view of a possible application in optical data
storage devices, diffraction grating efficiency of an organic dye, Acid
Fuchsin doped in PMMA matrix was studied under excitation with
CW diode pumped Nd: YAG laser at 532 nm. The open aperture Zscan
of dye doped polymer displayed saturable absorption and the
closed aperture Z-scan of the samples exhibited negative
nonlinearity. The diffraction efficiency of the grating is the ratio of
the intensity of the first order diffracted power to the incident read
beam power. The dye doped polymer films were found to be good
media for recording. It is observed that the formation of gratings
strongly depend on the concentration of dye in the polymer film, the
intensity ratios of the writing beams and the angle between the
writing beams. It has been found that efficient writing can be made at
an angle of 20o and when the intensity ratio of the writing beams is
unity.
Abstract: Photonic Crystal Fibers (PCFs) can be used in optical
communications as transmission lines. For this reason, the PCFs with
low confinement loss, low chromatic dispersion, and low nonlinear
effects are highly suitable transmission media. In this paper, we
introduce a new design of index-guiding nanostructured photonic
crystal fiber (IG-NPCF) with ultra-low chromatic dispersion, low
nonlinearity effects, and low confinement loss. Relatively low
dispersion is achieved in the wavelength range of 1200 to 1600nm
using the proposed design. According to the new structure of
nanostructured PCF presented in this study, the chromatic dispersion
slope is -30(ps/km.nm) and the confinement loss reaches below 10-7
dB/km. While in the wavelength range mentioned above at the same
time an effective area of more than 50.2μm2 is obtained.