Abstract: In the present work, an attempt has been made to
understand the feasibility of using UHF technique for identification
of any corona discharges/ arcing in insulating material due to water
droplets. The sensors of broadband type are useful for identification
of such discharges. It is realised that arcing initiated by liquid droplet
radiates UHF signals in the entire bandwidth up to 2 GHz. The
frequency content of the UHF signal generated due to corona/arcing
is not much varied in epoxy nanocomposites with different weight
percentage of clay content. The exfoliated/intercalated properties
were analysed through TEM studies. It is realized that corona
initiated discharges are of intermittent process. The hydrophobicity
of the material characterized through contact angle measurement. It
is realized that low Wt % of nanoclay content in epoxy resin reduces
the surface carbonization due to arcing/corona discharges. The results
of the study with gamma irradiated specimen indicates that contact
angle, discharge inception time and evaporation time of the liquid are
much lower than the virgin epoxy nanocomposite material.
Abstract: Bursa, since the establishment of the Ottoman Empire,
being on the important trade roads and having a capital accumulation
as a result of silk production, was one of the first cities of
modernization activities applied. Bursa maintained its importance
even during the Republican Period and became one of the most
important cities of the country and today is the fourth biggest and the
industrialized city in Turkey. Social, political, economical and
cultural changes occured with the reforms starting with the 1839
Edict of Tanzimat that aimed at modernizing the society and the
government and centralizing the political power began in the
Ottoman Empire. After the Tanzimat Reforms transformation of the
city changed and planning processes began in Bursa according to the
vision of Governors. The theresholds of the city are very important
data for a sustainable planning for the city planners. Main aim of this
study is to investigate the changes and transformations of the city
according to the changes in the socio-economical and cultural
properties for the city planners.
Abstract: The study aimed to verify a hypothesis that a sense of
fulfillment in student life and perceived stress in training in the
facilities could affect vocational identity among social welfare
university students, in order to acquire implications for enhancing the
vocational consciousness. A questionnaire survey was conducted with
388 third- and fourth-year students of training course for certified
social workers in three universities in A prefecture in Japan. The
questionnaire was returned by 338 students, and 288 responses
(85.2%) were valid and used for the analysis. As a SEM result, the
hypothesized model proved to be fit to the data. Path coefficient of
sense of fulfillment of student life to vocational identity was
statistically positive. Path coefficient of training stress to vocational
identity was statistically negative.
Abstract: Dehydration of methanol to dimethyl ether (DME)
over a commercial Al2O3 catalyst was studied in an isothermal integral
fixed bed reactor. The experiments were performed on the temperature
interval 513-613 K, liquid hourly space velocity (LHSV) of 0.9-2.1h-1,
pressures between 0.1 and 1.0 MPa. The effect of different operation
conditions on the dehydration of methanol was investigated in a
laboratory scale experiment. A new intrinsic kinetics equation based
on the mechanism of Langmuir-Hinshelwood dissociation adsorption
was developed for the dehydration reaction by fitting the expressions
to the experimental data. An activation energy of 67.21 kJ/mol was
obtained for the catalyst with the best performance. Statistic test
showed that this new intrinsic kinetics equation was acceptable.
Abstract: A numerical study on the turbulent flow and heat
transfer characteristics in the rectangular channel with different types
of baffles is carried out. The inclined baffles have the width of 19.8
cm, the square diamond type hole having one side length of 2.55 cm,
and the inclination angle of 5o. Reynolds number is varied between
23,000 and 57,000. The SST turbulence model is applied in the
calculation. The validity of the numerical results is examined by the
experimental data. The numerical results of the flow field depict that
the flow patterns around the different baffle type are entirely different
and these significantly affect the local heat transfer characteristics.
The heat transfer and friction factor characteristics are significantly
affected by the perforation density of the baffle plate. It is found that
the heat transfer enhancement of baffle type II (3 hole baffle) has the
best values.
Abstract: In the study of chironomids in Armenia several
species of Orthocladiinae subfamily of Cricotopus genus,
Diamesinae subfamily of Diamesa genus, and Chironominae
subfamily of Chironomus genus, have been identified. In the
Cricotopus genus two sibling species were found, not distinguishable
by larval morphological features, but clearly distinct cytogenetically.
Abstract: In this paper back-propagation artificial neural network
(BPANN )with Levenberg–Marquardt algorithm is employed to
predict the deformation of the upsetting process. To prepare a
training set for BPANN, some finite element simulations were
carried out. The input data for the artificial neural network are a set
of parameters generated randomly (aspect ratio d/h, material
properties, temperature and coefficient of friction). The output data
are the coefficient of polynomial that fitted on barreling curves.
Neural network was trained using barreling curves generated by
finite element simulations of the upsetting and the corresponding
material parameters. This technique was tested for three different
specimens and can be successfully employed to predict the
deformation of the upsetting process
Abstract: We have fabricated a-IGZO TFT and investigated the
stability under positive DC and AC bias stress. The threshold voltage
of a-IGZO TFT shifts positively under those biases, and that reduces
on-current. For this reason, conventional shift-register circuit
employing TFTs which stressed by positive bias will be unstable, may
do not work properly. We have designed a new 6-transistor
shift-register, which has less transistors than prior circuits. The TFTs
of the proposed shift-register are not suffering from positive DC or AC
stress, mainly kept unbiased. Despite the compact design, the stable
output signal was verified through the SPICE simulation even under
RC delay of clock signal.
Abstract: Most standard software development methodologies
are often not applied to software projects in many developing
countries of the world. The approach generally practice is close to
what eXtreme Programming (XP) is likely promoting, just keep
coding and testing as the requirement evolves. XP is an agile
software process development methodology that has inherent
capability for improving efficiency of Business Software
Development (BSD). XP can facilitate Business-to-Development
(B2D) relationship due to its customer-oriented advocate. From
practitioner point of view, we applied XP to BSD and result shows
that customer involvement has positive impact on productivity, but
can as well frustrate the success of the project. In an effort to
promote software engineering practice in developing countries of
Africa, we present the experiment performed, lessons learned,
problems encountered and solution adopted in applying XP
methodology to BSD.
Abstract: Today, incorrect use of lands and land use changes,
excessive grazing, no suitable using of agricultural farms, plowing on
steep slopes, road construct, building construct, mine excavation etc
have been caused increasing of soil erosion and sediment yield. For
erosion and sediment estimation one can use statistical and empirical
methods. This needs to identify land unit map and the map of
effective factors. However, these empirical methods are usually time
consuming and do not give accurate estimation of erosion. In this
study, we applied GIS techniques to estimate erosion and sediment of
Menderjan watershed at upstream Zayandehrud river in center of
Iran. Erosion faces at each land unit were defined on the basis of land
use, geology and land unit map using GIS. The UTM coordinates of
each erosion type that showed more erosion amounts such as rills and
gullies were inserted in GIS using GPS data. The frequency of
erosion indicators at each land unit, land use and their sediment yield
of these indices were calculated. Also using tendency analysis of
sediment yield changes in watershed outlet (Menderjan hydrometric
gauge station), was calculated related parameters and estimation
errors. The results of this study according to implemented watershed
management projects can be used for more rapid and more accurate
estimation of erosion than traditional methods. These results can also
be used for regional erosion assessment and can be used for remote
sensing image processing.
Abstract: A model-free robust control (MFRC) approach is proposed for position control of robot manipulators in the state space. The control approach is verified analytically to be robust subject to uncertainties including external disturbances, unmodeled dynamics, and parametric uncertainties. There is a high flexibility to work on different systems including actuators by the use of the proposed control approach. The proposed control approach can guarantee the robustness of control system. A PUMA 560 robot driven by geared permanent magnet dc motors is simulated. The simulation results show a satisfactory performance for control system under technical specifications. KeywordsModel-free, robust control, position control, PUMA 560.
Abstract: This paper investigates vortex shedding processes
occurring at the end of a stack of parallel plates, due to an oscillating
flow induced by an acoustic standing wave within an acoustic
resonator. Here, Particle Image Velocimetry (PIV) is used to quantify
the vortex shedding processes within an acoustic cycle
phase-by-phase, in particular during the “ejection" of the fluid out of
the stack. Standard hot-wire anemometry measurement is also applied
to detect the velocity fluctuations near the end of the stack.
Combination of these two measurement techniques allowed a detailed
analysis of the vortex shedding phenomena. The results obtained show
that, as the Reynolds number varies (by varying the plate thickness
and drive ratio), different flow patterns of vortex shedding are
observed by the PIV measurement. On the other hand, the
time-dependent hot-wire measurements allow obtaining detailed
frequency spectra of the velocity signal, used for calculating
characteristic Strouhal numbers. The impact of the plate thickness and
the Reynolds number on the vortex shedding pattern has been
discussed. Furthermore, a detailed map of the relationship between the
Strouhal number and Reynolds number has been obtained and
discussed.
Abstract: The objective of the research was to evaluate the
hardness stability of milk pomade sweets packed in several
packaging materials (OPP, Multibarrier 60 HFP, BIALON 65
HFP, BIALON 50 HFP, ECOLEAN) by several packaging
technologies – modified atmosphere (MAP) (consisting of
30% CO2+70% N2; 30% N2+70% CO2 and 100% CO2) and
control – in air ambiance. Samples were stored at the room
temperature +21±1 °C. The studies of the samples were
carried out before packaging and after 2, 4, 6, 8, and 10
storage weeks.
Abstract: Power systems and transformer are intrinsic apparatus, therefore its reliability and safe operation is important to determine their operation conditions, and the industry uses quality control tests in the insulation design of oil filled transformers. Hence the service period effect on AC dielectric strength is significant. The effect of aging on transformer oil physical, chemical and electrical properties was studied using the international testing methods for the evaluation of transformer oil quality. The study was carried out on six transformers operate in the field and for monitoring periods over twenty years. The properties which are strongly time dependent were specified and those which have a great impact on the transformer oil acidity, breakdown voltage and dissolved gas analysis were defined. Several tests on the transformers oil were studied to know the time of purifying or changing it, moreover prediction of the characteristics of it under different operation conditions.
Abstract: Manufacturing tolerancing is intended to determine
the intermediate geometrical and dimensional states of the part
during its manufacturing process. These manufacturing dimensions
also serve to satisfy not only the functional requirements given in
the definition drawing, but also the manufacturing constraints, for
example geometrical defects of the machine, vibration and the
wear of the cutting tool. In this paper, an experimental study on the
influence of the wear of the cutting tool (systematic dispersions) is
explored. This study was carried out on three stages .The first stage
allows machining without elimination of dispersions (random,
systematic) so the tolerances of manufacture according to total
dispersions. In the second stage, the results of the first stage are
filtered in such way to obtain the tolerances according to random
dispersions. Finally, from the two previous stages, the systematic
dispersions are generated. The objective of this study is to model
by the least squares method the error of manufacture based on
systematic dispersion. Finally, an approach of optimization of the
manufacturing tolerances was developed for machining on a CNC
machine tool
Abstract: The leaching rate of 137Cs from spent mix bead (anion and cation) exchange resins in a cement-bentonite matrix has been studied. Transport phenomena involved in the leaching of a radioactive material from a cement-bentonite matrix are investigated using three methods based on theoretical equations. These are: the diffusion equation for a plane source an equation for diffusion coupled to a firstorder equation and an empirical method employing a polynomial equation. The results presented in this paper are from a 25-year mortar and concrete testing project that will influence the design choices for radioactive waste packaging for a future Serbian radioactive waste disposal center.
Abstract: The authors present optimization parameters of rotary
positioner controller in hard disk drive servo track writing process
using coefficient diagram method; CDM. Due to estimation
parameters in PI Positioning Control System by expected ratio
method cannot meet the required specification of response
effectively, we suggest coefficient diagram method for defining
controller parameters under the requirement of the system. Finally,
the simulation results show that our proposed method can improve
the problem in tuning parameter of rotary positioner controller. It is
satisfied specification of performance of control system. Furthermore,
it is very convenient as a fast adjustment damping ratio as well as a
high speed response.
Abstract: This paper presents an experimental investigation of
transformer dielectric response and solid insulation water content.
The dielectric response was carried out on the base of Hybrid
Frequency Dielectric Spectroscopy and Polarization Current
measurements method (FDS &PC). The calculation of the water
content in paper is based on the water content in oil and the obtained
equilibrium curves. A reference measurements were performed at
equilibrium conditions for water content in oil and paper of
transformer at different stable temperatures (25, 50, 60 and 70°C) to
prepare references to evaluate the insulation behavior at the not
equilibrium conditions. Some measurements performed at the
different simulated normal working modes of transformer operation
at the same temperature where the equilibrium conditions. The
obtained results show that when transformer temperature is mach
more than the its ambient temperature, the transformer temperature
decreases immediately after disconnecting the transformer from the
network and this temperature reduction influences the transformer
insulation condition in the measuring process. In addition to the oil
temperature at the near places to the sensors, the temperature
uniformity in transformer which can be changed by a big change in
the load of transformer before the measuring time will influence the
result. The investigations have shown that the extremely influence of
the time between disconnecting the transformer and beginning the
measurements on the results. And the online monitoring for water
content in paper measurements, on the basis of the oil water content
on line monitoring and the obtained equilibrium curves. The
measurements where performed continuously and for about 50 days
without any disconnection in the prepared the adiabatic room.
Abstract: Performance of a dual maximal ratio combining
receiver has been analyzed for M-ary coherent and non-coherent
modulations over correlated Nakagami-m fading channels with nonidentical
and arbitrary fading parameter. The classical probability
density function (PDF) based approach is used for analysis.
Expressions for outage probability and average symbol error
performance for M-ary coherent and non-coherent modulations have
been obtained. The obtained results are verified against the special
case published results and found to be matching. The effect of the
unequal fading parameters, branch correlation and unequal input
average SNR on the receiver performance has been studied.
Abstract: The expansion mechanism of a partially ionized plasma produced by laser interaction with solid target (copper) is studied. For this purpose we use a hydrodynamical model which includes a source term combined with Saha's equation. The obtained self-similar solution in the limit of quasi-neutrality shows that the expansion, at the earlier stage, is driven by the combination of thermal pressure and electrostatic potential. They are of the same magnitude. The initial ionized fraction and the temperature are the leading parameters of the expanding profiles,