Abstract: Cement concrete is a complex mixture of different
materials. Behaviour of concrete depends on its mix proportions and
constituents when it is subjected to elevated temperatures. Principal
effects due to elevated temperatures are loss in compressive strength,
loss in weight or mass, change in colour and spall of concrete. The
experimental results of normal concrete and high strength concrete
subjected elevated temperatures at 200°C, 400°C, 600°C, and 800°C
and different cooling regimes viz. air cooling, water quenching on
different grade of concrete are reported in this paper.
Abstract: This paper discusses the undesirable charge transfer
through the parasitic capacitances of the input transistors in a
multi-inputs voltage sense amplifier. Its intrinsic rail-to-rail voltage
transitions at the output nodes inevitably disturb the input sides
through the capacitive coupling between the outputs and inputs. Then,
it can possible degrade the stabilities of the reference voltage levels.
Moreover, it becomes more serious in multi-channel systems by
altering them for other channels, and so degrades the linearity of the
overall systems. In order to alleviate the internal node voltage
transition, the internal node stabilization techniques are proposed. It
achieves 45% and 40% improvements for node stabilization and input
referred disturbance, respectively.
Abstract: In this paper, the effect of grades 32.4 and 42.5
Portland-limestone cements generally used for concrete production in
Nigeria on concrete compressive strength is investigated.
Investigation revealed that the compressive strength of concrete
produced with Portland-limestone cement grade 42.5 is generally
higher than that produced with cement grade 32.5. The percentage
difference between the compressive strengths of the concrete cubes
produced with Portland-limestone cement grades 42.5 and 32.5 is
inversely proportional to the richness of the concrete with the highest
and the least percentage difference associated with the 1:2:4 and
1:1:2 mix ratios respectively. It is recommended that cement grade
42.5 be preferred for construction in Nigeria as this will lead to the
construction of stronger concrete structures, which will reduce the
incidence of failure of building and other concrete structures at no
additional cost since the cost of both cement grades are the same.
Abstract: The California Bearing Ratio (CBR) has been
acknowledged as an important parameter to characterize the bearing
capacity of earth structures, such as earth dams, road embankments,
airport runways, bridge abutments and pavements. Technically, the
CBR test can be carried out in the laboratory or in the field. The CBR
test is time-consuming and is infrequently performed due to the
equipment needed and the fact that the field moisture content keeps
changing over time. Over the years, many correlations have been
developed for the prediction of CBR by various researchers,
including the dynamic cone penetrometer, undrained shear strength
and Clegg impact hammer. This paper reports and discusses some of
the results from a study on the prediction of CBR. In the current
study, the CBR test was performed in the laboratory on some finegrained
subgrade soils collected from various locations in Victoria.
Based on the test results, a satisfactory empirical correlation was
found between the CBR and the physical properties of the
experimental soils.
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: The absorption power generation cycle based on the
ammonia-water mixture has attracted much attention for efficient
recovery of low-grade energy sources. In this paper a thermodynamic
performance analysis is carried out for a Kalina cycle using
ammonia-water mixture as a working fluid for efficient conversion of
low-temperature heat source in the form of sensible energy. The
effects of the source temperature on the system performance are
extensively investigated by using the thermodynamic models. The
results show that the source temperature as well as the ammonia mass
fraction affects greatly on the thermodynamic performance of the
cycle.
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: Some regularities of formation of a new structural
state of the thermoplastic polymers - gradually oriented (stretched)
state (GOS) are discussed. Transition into GOS is realized by the
graded oriented stretching - by action of inhomogeneous mechanical
field on the isotropic linear polymers or by zone stretching that is
implemented on a standard tensile-testing machine with using a
specially designed zone stretching device (ZSD). Both technical
approaches (especially zone stretching method) allows to manage the
such quantitative parameters of gradually oriented polymers as a
range of change in relative elongation/orientation degree, length of
this change and profile (linear, hyperbolic, parabolic, logarithmic,
etc.). The possibility of obtaining functionally graded materials
(FGMs) by graded orientation method is briefly discussed. Uniaxial
graded stretching method should be considered as an effective
technological solution to create polymer materials with a
predetermined gradient of physical properties.
Abstract: In this study which has been conducted in Akçasu
Forest Range District of Devrek Forest Directorate; 3 methods (weed
control with labourer power, cover removal with Hitachi F20
Excavator, and weed control with agricultural equipment mounted on
a Ferguson 240S agriculture tractor) were utilized in weed control
efforts in regeneration of degraded oriental beech forests have been
compared. In this respect, 3 methods have been compared by
determining certain work hours and standard durations of unit areas
(1 hectare). For this purpose, evaluating the tasks made with human
and machine force from the aspects of duration, productivity and
costs, it has been aimed to determine the most productive method in
accordance with the actual ecological conditions of research field.
Within the scope of the study, the time studies have been conducted
for 3 methods used in weed control efforts. While carrying out those
studies, the performed implementations have been evaluated by
dividing them into business stages. Also, the actual data have been
used while calculating the cost accounts. In those calculations, the
latest formulas and equations which are also used in developed
countries have been utilized. The variance of analysis (ANOVA) was
used in order to determine whether there is any statistically
significant difference among obtained results, and the Duncan test
was used for grouping if there is significant difference. According to
the measurements and findings carried out within the scope of this
study, it has been found during living cover removal efforts in
regeneration efforts in demolished oriental beech forests that the
removal of weed layer in 1 hectare of field has taken 920 hours with
labourer force, 15.1 hours with excavator and 60 hours with an
equipment mounted on a tractor. On the other hand, it has been
determined that the cost of removal of living cover in unit area (1
hectare) was 3220.00 TL for labourer power, 1250 TL for excavator
and 1825 TL for equipment mounted on a tractor.
According to the obtained results, it has been found that the
utilization of excavator in weed control effort in regeneration of
degraded oriental beech regions under actual ecological conditions of
research field has been found to be more productive from both of
aspects of duration and costs. These determinations carried out
should be repeated in weed control efforts in degraded forest fields
with different ecological conditions, it is compulsory for finding the
most efficient weed control method. These findings will light the way
of technical staff of forestry directorate in determination of the most
effective and economic weed control method. Thus, the more actual
data will be used while preparing the weed control budgets, and there
will be significant contributions to national economy. Also the results of this and similar studies are very important for developing the policies for our forestry in short and long term.
Abstract: Over the last few decades, oilfield service rolling
equipment has significantly increased in weight, primarily because of
emissions regulations, which require larger/heavier engines, larger
cooling systems, and emissions after-treatment systems, in some
cases, etc. Larger engines cause more vibration and shock loads,
leading to failure of electronics and control systems.
If the vibrating frequency of the engine matches the system
frequency, high resonance is observed on structural parts and mounts.
One such existing automated control equipment system comprising
wire rope mounts used for mounting computers was designed
approximately 12 years ago. This includes the use of an industrialgrade
computer to control the system operation. The original
computer had a smaller, lighter enclosure. After a few years, a newer
computer version was introduced, which was 10 lbm heavier. Some
failures of internal computer parts have been documented for cases in
which the old mounts were used. Because of the added weight, there
is a possibility of having the two brackets impact each other under
off-road conditions, which causes a high shock input to the computer
parts. This added failure mode requires validating the existing mount
design to suit the new heavy-weight computer.
This paper discusses the modal finite element method (FEM)
analysis and experimental modal analysis conducted to study the
effects of vibration on the wire rope mounts and the computer. The
existing mount was modelled in ANSYS software, and resultant
mode shapes and frequencies were obtained. The experimental modal
analysis was conducted, and actual frequency responses were
observed and recorded.
Results clearly revealed that at resonance frequency, the brackets
were colliding and potentially causing damage to computer parts. To
solve this issue, spring mounts of different stiffness were modeled in
ANSYS software, and the resonant frequency was determined.
Increasing the stiffness of the system increased the resonant
frequency zone away from the frequency window at which the engine
showed heavy vibrations or resonance. After multiple iterations in
ANSYS software, the stiffness of the spring mount was finalized,
which was again experimentally validated.
Abstract: Periventricular Leukomalacia (PVL) is a White Matter
Injury (WMI) of preterm neonatal brain. Objectives of the study were
to assess the neuro-developmental outcome at one year of age and to
determine a good protocol of cranial ultrasonography to detect PVL.
Two hundred and sixty four preterm neonates were included in the
study. Series of cranial ultrasound scans were done by using a
dedicated neonatal head probe 4-10 MHz of Logic e portable
ultrasound scanner. Clinical history of seizures, abnormal head
growth (hydrocephalus or microcephaly) and developmental
milestones were assessed and neurological examinations were done
until one year of age. Among live neonates, 57% who had cystic PVL
(Grades 2 and 3) manifested as cerebral palsy. In conclusion cystic
PVL has permanent neurological disabilities like cerebral palsy.
Good protocol of real time cranial ultrasonography to detect PVL is
to perform scans at least once a week until one month and at term (40
weeks of gestation).
Abstract: The IEEE 802.22 working group aims to drive the
Digital Video Broadcasting-Terrestrial (DVB-T) bands for data
communication to the rural area without interfering the TV broadcast.
In this paper, we arrive at a closed-form expression for average
detection probability of Fusion center (FC) with multiple antenna
over the κ − μ fading channel model. We consider a centralized
cooperative multiple antenna network for reporting. The DVB-T
samples forwarded by the secondary user (SU) were combined using
Maximum ratio combiner at FC, an energy detection is performed
to make the decision. The fading effects of the channel degrades
the detection probability of the FC, a generalized independent and
identically distributed (IID) κ − μ and an additive white Gaussian
noise (AWGN) channel is considered for reporting and sensing
respectively. The proposed system performance is verified through
simulation results.
Abstract: Heavy rare earth (HRE) oxalate concentrates were
prepared from the Egyptian crude monazite sand (graded about 47%).
The concentrates were specified quantitatively for their constituents
of individual rare earth elements using ion chromatograph (IC) and
qualitatively by scanning electron microscope (SEM) for the other
major constituents. The 1st concentrate was composed of 10.5%
HREE where 7.25% of them represented yttrium. The 2nd concentrate
contained about 41.7% LREE, 17.5% HREE and 13.6% Th. The
LREE involved 18.3% Ce, 10.5% La and 8% Nd while the HREE
were 8.7% Y, 3.5% Gd and 2.9% Dy. The 3rd concentrate was
containing about 8.0% LREE (3.7% Ce, 2.0% La and 1.5% Nd),
10.2% HREE (6.4% yttrium and 2.0% Dy) and 2.1% uranium. The
final concentrate comprised 0.84% uranium beside iron, chromium
and traces of REE.
Abstract: In wireless communication, space-time block code (STBC), cyclic delay diversity (CDD) and space-time cyclic delay diversity (STCDD)are used as the spatial diversity schemes and have been widely studied for the reliablecommunication. If these schemes are used, the communication system can obtain the improved performance. However,the quality of the system is degraded when the distance between a source and a destination is distant in wireless communication system. In this paper, the cooperative transmission scheme using two sources is proposed and improves the performance of the wireless communication system.
Abstract: Asphaltic concrete for pavement construction in India
are produced by using crushed stone, gravels etc. as aggregate. In
north-Eastern region of India, there is a scarcity of stone aggregate.
Therefore the road engineers are always in search of an optional
material as aggregate which can replace the regularly used material.
The purpose of this work was to evaluate the utilization of
substandard or marginal aggregates in flexible pavement
construction. The investigation was undertaken to evaluate the effects
of using lower quality aggregates such as over burnt brick aggregate
on the preparation of asphalt concrete for flexible pavements. The
scope of this work included a review of available literature and
existing data, a laboratory evaluation organized to determine the
effects of marginal aggregates and potential techniques to upgrade
these substandard materials, and a laboratory evaluation of these
upgraded marginal aggregate asphalt mixtures. Over burnt brick
aggregates are water susceptible and can leads to moisture damage.
Moisture damage is the progressive loss of functionality of the
material owing to loss of the adhesion bond between the asphalt
binder and the aggregate surface. Hence zycosoil as an anti striping
additive were evaluated in this study. This study summarizes the
results of the laboratory evaluation carried out to investigate the
properties of asphalt concrete prepared with zycosoil modified over
burnt brick aggregate. Marshall specimen were prepared with stone
aggregate, zycosoil modified stone aggregate, over burnt brick
aggregate and zycosoil modified over burnt brick aggregate. Results
show that addition of zycosoil with stone aggregate increased
stability by 6% and addition of zycosoil with over burnt brick
aggregate increased stability by 30%.
Abstract: Essential oils are expensive phytochemicals produced
and extracted from specific species belonging to particular families in
the plant kingdom. In the United Arab Emirates country (UAE), is
located in the arid region of the world, nine species, from the
Lamiaceae family, having the capability to produce therapeutic grade
essential oils. These species include; Mentha spicata, Ocimum
forskolei, Salvia macrosiphon, Salvia aegyptiaca, Salvia macilenta,
Salvia spinosa, Teucrium polium, Teucrium stocksianum and Zataria
multiflora. Although, such potential species are indigenous to the
UAE, however, there are almost no studies available to investigate
the chemical composition and the quality of the extracted essential
oils under the UAE climatological conditions. Therefore, great
attention has to be given to such valuable natural resources, through
conducting highly supported research projects, tailored to the UAE
conditions, and investigating different extraction techniques,
including the application of the latest available technologies, such as
superficial fluid CO2. This is crucially needed; in order to accomplish
the greatest possibilities in the medicinal field, specifically in the
discovery of new therapeutic chemotypes, as well as, to achieve the
sustainability of this natural resource in the country.
Abstract: Age ratings are very helpful in providing parents with
relevant information for the purchase and use of digital technologies
by the children; this is why the non-definition of age ratings for the
use of ICTs by children in schools is a major concern; and this
problem serves as a motivation for this study whose aim is to
examine the factors affecting the perceptions of educators on the
learners’ youngest age for the introduction of ICTs in schools. This
aim is achieved through two types of research objectives: the
identification and design of theories and models on age ratings, and
the empirical testing of such theories and models in a survey of
educators from the Camperdown district of the South African
KwaZulu-Natal province. A questionnaire is used for the collection
of the data of this survey whose validity and reliability is checked in
SPSS prior to its descriptive and correlative quantitative analysis. The
main hypothesis supporting this research is the association between
the demographics of educators, their personality, and their
perceptions on the learners’ youngest age for the introduction of ICTs
in schools; as claimed by existing research; except that the present
study looks at personality from three dimensions: self-actualized
personalities, fully functioning personalities, and healthy
personalities. This hypothesis was fully confirmed by the empirical
study conducted by this research except for the demographic factor
where only the educators’ grade or class was found to be associated
with the personality of educators.
Abstract: In this paper, thick walled Cylindrical tanks or tubes
made of functionally graded material under internal pressure and
temperature gradient are studied. Material parameters have been
considered as power functions. They play important role in the
elastoplastic behavior of these materials. To clarify their role,
different materials with different parameters have been used under
temperature gradient. Finally, their effect and loading effect have
been determined in first yield point. Also, the important role of
temperature gradient was also shown. At the end the study has been
results obtained from changes in the elastic modulus and yield stress.
Also special attention is also given to the effects of this internal
pressure and temperature gradient in the creation of tensile and
compressive stresses.
Abstract: The main objective of this study was to identify
factors and conditions that motivated and encouraged students
towards the math class and the factors that made this class an
attractive and lovely one. To do this end, questionnaires consisting of
15 questions were distributed among 85 math teachers working in
schools of Zahedan. Having collected and reviewed these
questionnaires, it was shown that doing activity in math class
(activity of students while teaching) and previous math teachers'
behaviors have had much impact on encouraging the students
towards mathematics. Separation of educational classroom of
mathematics from the main classroom (which is decorated with crafts
created by students themselves with regard to math book including
article, wall newspaper, figures and formulas), peers, size and
appearance of math book, first grade teachers in each educational
level, among whom the Elementary first grade teachers had more
importance and impact, were among the most influential and
important factors in this regard. Then, school environment, family,
conducting research related to mathematics, its application in daily
life and other courses and studying the history of mathematics were
categorized as important factors that would increase the students’
interest in mathematics.
Abstract: In this paper influence of packaging method (vacuum
and modified atmosphere packaging) on lipid oxidative stability and
sensory properties of odor and taste of the traditional sausage
Petrovská klobása were examined. These parameters were examined
during storage period (7 months). In the end of storage period,
vacuum packed sausage showed better oxidative stability. Propanal
content was significantly lower (P