Abstract: Ceramic obtained on the base of aluminum oxide has
wide application range, because it has unique properties, for example,
wear-resistance, dielectric characteristics, and exploitation ability at
high temperatures and in corrosive atmosphere. Low temperature
synthesis of α-Al2O3 is energo-economical process and it is topical
for developing technologies of corundum ceramics fabrication. In the present work possibilities of low temperature transformation
of oxyhydroxides in α-Al2O3, during the presence of small amount of
rare–earth elements compounds (also Th, Re), have been discussed.
Aluminum unstable oxyhydroxides have been obtained by hydrolysis
of aluminium isopropoxide, nitrates, sulphate, and chloride in
alkaline environment at 80-90ºC temperatures. β-Al(OH)3 has been
received from aluminum powder by ultrasonic development. Drying
of oxyhydroxide sol has been conducted with presence of various
types seeds, which amount reaches 0,1-0,2% (mas). Neodymium,
holmium, thorium, lanthanum, cerium, gadolinium, disprosium
nitrates and rhenium carbonyls have been used as seeds and they
have been added to the sol specimens in amount of 0.1-0.2% (mas)
calculated on metals. Annealing of obtained gels is carried out at 70–
1100ºC for 2 hrs. The same specimen transforms in α-Al2O3 at
1100ºC. At this temperature in case of presence of lanthanum and
gadolinium transformation takes place by 70-85%. In case of
presence of thorium stabilization of γ-and θ-phases takes place. It is
established, that thorium causes inhibition of α-phase generation at
1100ºC, and at the time when in all other doped specimens α-phase is
generated at lower temperatures (1000-1050ºC). Synthesis of various
type compounds and simultaneous consolidation has developed in the
furnace of OXY-GON. Composite materials containing oxide and
non-oxide components close to theoretical data have been obtained in
this furnace respectively. During the work the following devices have
been used: X-ray diffractometer DRON-3M (Cu-Kα, Ni filter,
2º/min), High temperature vacuum furnace OXY-GON, electronic
scanning microscopes Nikon ECLIPSE LV 150, NMM-800TRF,
planetary mill Pulverisette 7 premium line, SHIMADZU Dynamic
Ultra Micro Hardness Tester, DUH-211S, Analysette 12 Dyna sizer.
Abstract: The Radio Frequency Identification (RFID) technology
has a diverse base of applications, but it is also prone to security
threats. There are different types of security attacks which limit the
range of the RFID applications. For example, deploying the RFID
networks in insecure environments could make the RFID system
vulnerable to many types of attacks such as spoofing attack, location
traceability attack, physical attack and many more. Therefore, security
is often an important requirement for RFID systems. In this paper,
RFID mutual authentication protocol is implemented based on mobile
agent technology and timestamp, which are used to provide strong
authentication and integrity assurances to both the RFID readers and
their corresponding RFID tags. The integration of mobile agent
technology and timestamp provides promising results towards
achieving this goal and towards reducing the security threats in RFID
systems.
Abstract: In the present study we have investigated axial
buckling characteristics of nanocomposite beams reinforced by
single-walled carbon nanotubes (SWCNTs). Various types of beam
theories including Euler-Bernoulli beam theory, Timoshenko beam
theory and Reddy beam theory were used to analyze the buckling
behavior of carbon nanotube-reinforced composite beams.
Generalized differential quadrature (GDQ) method was utilized to
discretize the governing differential equations along with four
commonly used boundary conditions. The material properties of the
nanocomposite beams were obtained using molecular dynamic (MD)
simulation corresponding to both short-(10,10) SWCNT and long-
(10,10) SWCNT composites which were embedded by amorphous
polyethylene matrix. Then the results obtained directly from MD
simulations were matched with those calculated by the mixture rule
to extract appropriate values of carbon nanotube efficiency
parameters accounting for the scale-dependent material properties.
The selected numerical results were presented to indicate the
influences of nanotube volume fractions and end supports on the
critical axial buckling loads of nanocomposite beams relevant to
long- and short-nanotube composites.
Abstract: Mineral oil is commonly used for high voltage
transformer insulation. The insulation quality of mineral oil is
affecting the operation process of high voltage transformer. There are
many contaminations which could decrease the insulation quality of
mineral oil. One of them is water. This research talks about the effect
of water content on dielectric properties, physic properties, and
partial discharge pattern on mineral oil. Samples were varied with 10
varieties of water content value. And then all samples would be tested
to measure the dielectric properties, physic properties, and partial
discharge pattern. The result of this research showed that an
increment of water content value would decrease the insulation
quality of mineral oil.
Abstract: For schools to be desirable places in which to work, it
is necessary for principals to recognise their teachers’ emotions, and
be sensitive to their needs. This necessitates that principals are
capable to correctly identify their emotionally intelligent behaviours
(EIBs) they need to use in order to be successful leaders. They also
need to have knowledge of their emotional intelligence and be able to
identify the factors and situations that evoke emotion at an
interpersonal level. If a principal is able to do this, then the control
and understanding of emotions and behaviours of oneself and others
could improve vastly. This study focuses on the interpersonal EIBS
of principals affecting the job satisfaction of teachers. The correlation
coefficients in this quantitative study strongly indicate that there is a
statistical significance between the respondents’ level of job
satisfaction, the rating of their principals’ EIBs and how they believe
their principals’ EIBs will affect their sense of job satisfaction. It can
be concluded from the data obtained in this study that there is a
significant correlation between the sense of job satisfaction of
teachers and their principals’ interpersonal EIBs. This means that the
more satisfied a teacher is at school, the more appropriate and
meaningful a principal’s EIBs will be. Conversely, the more
dissatisfied a teacher is at school the less appropriate and less
meaningful a principal’s interpersonal EIBs will be. This implies that
the leaders’ EIBs can be construed as one of the major factors
affecting the job satisfaction of employees.
Abstract: The influence of Islam on arts can be found primarily
in calligraphy, arabesque designs and architecture. Also, geometric
designs were used quite extensively. Muslim craftsmen produced
stunning designs based on simple geometric principles and traditional
motifs which were used to decorate many surfaces. The idea of
interlacing simple rectilinear lines to form the patterns impressed
Arabs. Nomads of Persia, Turks and Mongols were equally
impressed with the designs so they begin to use them in their homes
in carpet weaving. Islamic designs, motifs and colours which were
used became common place and served to influence people’s tastes.
Modern life style and contemporary products have changed the style
of people’s daily lives, however, people still long for the nomadic
way of life. This is clearly reflected in people’s homes. In a great
many Muslim homes, Islamic decorative motifs can be seen along
with traditional ‘Bedouin’ style furnishing, especially in homes of the
Arabian Peninsula.
Abstract: An analytical 4-DOF nonlinear model of a de Laval
rotor-stator system based on Energy Principles has been used
theoretically and experimentally to investigate fault symptoms in a
rotating system. The faults, namely rotor-stator-rub, crack and
unbalance are modeled as excitations on the rotor shaft. Mayes
steering function is used to simulate the breathing behaviour of the
crack. The fault analysis technique is based on waveform signal,
orbits and Fast Fourier Transform (FFT) derived from simulated and
real measured signals. Simulated and experimental results manifest
considerable mutual resemblance of elliptic-shaped orbits and FFT
for a same range of test data.
Abstract: Nonlinear evolution of broadband ultrasonic pulses
passed through the rock specimens is studied using the apparatus
“GEOSCAN-02M”. Ultrasonic pulses are excited by the pulses of Qswitched
Nd:YAG laser with the time duration of 10 ns and with the
energy of 260 mJ. This energy can be reduced to 20 mJ by some light
filters. The laser beam radius did not exceed 5 mm. As a result of the
absorption of the laser pulse in the special material – the optoacoustic
generator–the pulses of longitudinal ultrasonic waves are excited with
the time duration of 100 ns and with the maximum pressure
amplitude of 10 MPa. The immersion technique is used to measure
the parameters of these ultrasonic pulses passed through a specimen,
the immersion liquid is distilled water. The reference pulse passed
through the cell with water has the compression and the rarefaction
phases. The amplitude of the rarefaction phase is five times lower
than that of the compression phase. The spectral range of the
reference pulse reaches 10 MHz. The cubic-shaped specimens of the
Karelian gabbro are studied with the rib length 3 cm. The ultimate
strength of the specimens by the uniaxial compression is (300±10)
MPa. As the reference pulse passes through the area of the specimen
without cracks the compression phase decreases and the rarefaction
one increases due to diffraction and scattering of ultrasound, so the
ratio of these phases becomes 2.3:1. After preloading some horizontal
cracks appear in the specimens. Their location is found by one-sided
scanning of the specimen using the backward mode detection of the
ultrasonic pulses reflected from the structure defects. Using the
computer processing of these signals the images are obtained of the
cross-sections of the specimens with cracks. By the increase of the
reference pulse amplitude from 0.1 MPa to 5 MPa the nonlinear
transformation of the ultrasonic pulse passed through the specimen
with horizontal cracks results in the decrease by 2.5 times of the
amplitude of the rarefaction phase and in the increase of its duration
by 2.1 times. By the increase of the reference pulse amplitude from 5
MPa to 10 MPa the time splitting of the phases is observed for the
bipolar pulse passed through the specimen. The compression and
rarefaction phases propagate with different velocities. These features
of the powerful broadband ultrasonic pulses passed through the rock
specimens can be described by the hysteresis model of Preisach-
Mayergoyz and can be used for the location of cracks in the optically
opaque materials.
Abstract: Research has shown that techno-entrepreneurship is
economically significant. Therefore, it is suggested that teaching
techno-entrepreneurship may be important because such programmes
would prepare current and future generations of learners to recognise
and act on high-technology opportunities. Education in technoentrepreneurship
may increase the knowledge of how to start one’s
own enterprise and recognise the technological opportunities for
commercialisation to improve decision-making about starting a new
venture; also it influence decisions about capturing the business
opportunities and turning them into successful ventures. Universities
can play a main role in connecting and networking technoentrepreneurship
students towards a cooperative attitude with real
business practice and industry knowledge. To investigate and answer
whether education for techno-entrepreneurs really helps, this paper
choses a comparison of literature reviews as its method of research.
After reviewing literature related to the impact of technoentrepreneurship
education on self-employment 6 studies which had
similar aim and objective to this paper were. These particular papers
were selected based on a keywords search and as their aim,
objectives, and gaps were close to the current research. In addition,
they were all based on the influence of techno-entrepreneurship
education in self-employment and intention of students to start new
ventures. The findings showed that teaching techno-entrepreneurship
education may have an influence on students’ intention and their
future self-employment, but which courses should be covered and the
duration of programmes, needs further investigation.
Abstract: In this paper, we present a comparative study of three
methods of 2D face recognition system such as: Iso-Geodesic Curves
(IGC), Geodesic Distance (GD) and Geodesic-Intensity Histogram
(GIH). These approaches are based on computing of geodesic
distance between points of facial surface and between facial curves.
In this study we represented the image at gray level as a 2D surface in
a 3D space, with the third coordinate proportional to the intensity
values of pixels. In the classifying step, we use: Neural Networks
(NN), K-Nearest Neighbor (KNN) and Support Vector Machines
(SVM). The images used in our experiments are from two wellknown
databases of face images ORL and YaleB. ORL data base was
used to evaluate the performance of methods under conditions where
the pose and sample size are varied, and the database YaleB was used
to examine the performance of the systems when the facial
expressions and lighting are varied.
Abstract: Heart is the most important part in the body of living
organisms. It affects and is affected by any factor in the body.
Therefore, it is a good detector for all conditions in the body. Heart
signal is a non-stationary signal; thus, it is utmost important to study
the variability of heart signal. The Heart Rate Variability (HRV) has
attracted considerable attention in psychology, medicine and has
become important dependent measure in psychophysiology and
behavioral medicine. The standards of measurements, physiological
interpretation and clinical use for HRV that are most often used were
described in many researcher papers, however, remain complex
issues are fraught with pitfalls. This paper presents one of the nonlinear
techniques to analyze HRV. It discusses many points like, what
Poincaré plot is and how Poincaré plot works; also, Poincaré plot's
merits especially in HRV. Besides, it discusses the limitation of
Poincaré cause of standard deviation SD1, SD2 and how to overcome
this limitation by using complex correlation measure (CCM). The
CCM is most sensitive to changes in temporal structure of the
Poincaré plot as compared toSD1 and SD2.
Abstract: The problem of degradation of agricultural residues
from palm oil industry is increasing due to its expansion.
Lignocelloulosic waste from these industry represent large amount of
unutilized resources, this is due to their high lignin content. Since
white rot fungi are capable of degrading lignin, its potential for the
degradation of lignocelloulosic waste from palm oil industry was
accessed. The lignocellluloses content was measured before and after
biodegradation and the rate of reduction was determined. From the
results of the biodegradation, it was observed that hemicellulose
reduces by 22.62%, cellulose by 20.97% and lignin by 10.65% from
the initials lignocelluloses contents. Thus, to improve the digestibility
of palm oil mesocarp fibre, treatment by white rot-fungi is
recommended.
Abstract: It has been known that a characteristic
Burst-Suppression (BS) pattern appears in EEG during the early
recovery period following Cardiac Arrest (CA). Here, to explore the
relationship between cortical and subcortical neural activities
underlying BS, extracellular activity in the parietal cortex and the
centromedian nucleus of the thalamus and extradural EEG were
recorded in a rodent CA model. During the BS, the cortical firing rate
is extraordinarily high, and that bursts in EEG correlate to dense spikes
in cortical neurons. Newly observed phenomena are that 1) thalamic
activity reemerges earlier than cortical activity following CA, and 2)
the correlation coefficient of cortical and thalamic activities rises
during BS period. These results would help elucidate the underlying
mechanism of brain recovery after CA injury.
Abstract: Asphalt concrete pavements have a short life cycle,
failing mainly due to temperature changes, traffic loading and ageing.
Modified asphalt mixtures provide the technology to produce a
bituminous binder with improved viscoelastic properties, which
remain in balance over a wider temperature range and loading
conditions. In this research, 60/70 penetration grade asphalt binder
was modified by adding 2, 4, 6, 8 and 10 percent by weight of asphalt
binder following the wet process and the mineral aggregate was
modified by adding 1, 2, 3, 4 and 5 percent crumb rubber by volume
of the mineral aggregate following the dry process. The LDPE
modified asphalt binder rheological properties were evaluated. The
laboratory results showed an increase in viscosity, softening point
and stiffness of the binder. The modified asphalt was then used in
preparing asphalt mixtures by Marshall Mix design procedure. The
Marshall Stability values for mixes containing 2% crumb rubber and
4% LDPE were found to be 30% higher than the conventional asphalt
concrete mix.
Abstract: Carbon nanotubes (CNTs) are known for having high elastic properties with high surface area that promote them as good candidates for reinforcing polymeric matrices. In composite materials, CNTs lack chemical bonding with the surrounding matrix which decreases the possibility of better stress transfer between the components. In this work, a chemical treatment for activating the surface of the multi-wall carbon nanotubes (MWCNT) was applied and the effect of this functionalization on the elastic properties of the epoxy nanocomposites was studied. Functional amino-groups were added to the surface of the CNTs and it was evaluated to be about 34% of the total weight of the CNTs. Elastic modulus was found to increase by about 40% of the neat epoxy resin at CNTs’ weight fraction of 0.5%. The elastic modulus was found to decrease after reaching a certain concentration of CNTs which was found to be 1% wt. The scanning electron microscopic pictures showed the effect of the CNTs on the crack propagation through the sample by forming stress concentrated spots at the nanocomposite samples.
Abstract: The current-voltage (I-V) characteristics of Pd/n-GaN Schottky barrier were studied at temperatures over room temperature (300-470K). The values of ideality factor (n), zero-bias barrier height (φB0), flat barrier height (φBF) and series resistance (Rs) obtained from I-V-T measurements were found to be strongly temperature dependent while (φBo) increase, (n), (φBF) and (Rs) decrease with increasing temperature. The apparent Richardson constant was found to be 2.1x10-9 Acm-2K-2 and mean barrier height of 0.19 eV. After barrier height inhomogeneities correction, by assuming a Gaussian distribution (GD) of the barrier heights, the Richardson constant and the mean barrier height were obtained as 23 Acm-2K-2 and 1.78eV, respectively. The corrected Richardson constant was very closer to theoretical value of 26 Acm-2K-2.
Abstract: Students of Higher Education Technical School of
Professional Studies in Novi Sad follow the subject ‘Maintenance of
Electric Power Equipment’ at the Electrotechnical Department. This
paper presents educational plan and program of the subject
Maintenance of Electric Power Equipment. The course deals with the
problems of preventive and investing maintenance of transformer
stations (TS), performing and maintenance of grounding of TS and
pillars, as well as tracing and detection the location of the cables
failure. There is a special elaborated subject concerning the safe work
conditions for the electrician during network maintenance, as well as
the basics of making and keeping technical documentation of the
equipment.
Abstract: The main issue in designing a wireless sensor network
(WSN) is the finding of a proper routing protocol that complies with
the several requirements of high reliability, short latency, scalability,
low power consumption, and many others. This paper proposes a
novel routing algorithm that complies with these design
requirements. The new routing protocol divides the WSN into several subnetworks
and each sub-network is divided into several clusters. This
division is designed to reduce the number of radio transmission and
hence decreases the power consumption. The network division may
be changed dynamically to adapt with the network changes and
allows the realization of the design requirements.
Abstract: Target of this study was the analysis of the impact of
crude glycerol on canine spermatozoa motility, morphology,
viability, and membrane integrity. Experiments were realized in vitro.
In the study, semen from 5 large dog breeds was used. They were
typical representatives of large breeds, coming from healthy rearing,
regularly vaccinated and integrated to the further breeding. Semen
collections were realized at the owners of animals and in the
veterinary clinic. Subsequently the experiments were realized at the
Department of Animal Physiology of the SUA in Nitra. The
spermatozoa motility was evaluated using CASA analyzer
(SpermVisionTM, Minitub, Germany) at the temperature 5 and 37°C
for 5 hours. In the study, 13 motility parameters were evaluated.
Generally, crude glycerol has generally negative effect on
spermatozoa motility. Morphological analysis was realized using
Hancock staining and the preparations were evaluated at
magnification 1000x using classification tables of morphologically
changed spermatozoa. Data clearly detected the highest number of
morphologically changed spermatozoa in the experimental groups
(know twisted tails, tail torso and tail coiling). For acrosome
alterations swelled acrosomes, removed acrosomes and acrosomes
with undulated membrane were detected. In this study also the effect
of crude glycerol on spermatozoa membrane integrity were analyzed.
The highest crude glycerol concentration significantly affects
spermatozoa integrity. Results of this study show that crude glycerol
has effect of spermatozoa motility, viability, and membrane integrity.
Detected changes are related to crude glycerol concentration,
temperature, as well as time of incubation.
Abstract: Lots of motors have been being used in industry.
Therefore many researchers have studied about the failure diagnosis of
motors. In this paper, the effect of measuring environment for
diagnosis of gear fault connected to a motor shaft is studied. The fault
diagnosis is executed through the comparison of normal gear and
abnormal gear. The measured FFT data are compared with the normal
data and analyzed for q-axis current, noise and vibration. For bad and
good environment, the diagnosis results are compared. From these, it
is shown that the bad measuring environment may not be able to detect
exactly the motor gear fault. Therefore it is emphasized that the
measuring environment should be carefully prepared.