Abstract: We investigated oxidative DNA damage caused by
radio frequency radiation using 8-oxo-7, 8-dihydro-2'-
deoxyguanosine (8-oxodG) generated in mice tissues after exposure
to 900 MHz mobile phone radio frequency in three independent
experiments. The RF was generated by a Global System for Mobile
Communication (GSM) signal generator. The radio frequency field
was adjusted to 25 V/m. The whole body specific absorption rate
(SAR) was 1.0 W/kg. Animals were exposed to this field for 30 min
daily for 30 days. 24 h post-exposure, blood serum, brain and spleen
were removed and DNA was isolated. Enzyme-linked
immunosorbent assay (ELISA) was used to measure 8-oxodG
concentration. All animals survived the whole experimental period.
The body weight of animals did not change significantly at the end of
the experiment. No statistically significant differences observed in
the levels of oxidative stress. Our results are not in favor of the
hypothesis that 900 MHz RF induces oxidative damage.
Abstract: This paper analytically investigates the 3D flow
pattern at the confluences of two rectangular channels having 900
angles using Navier-Stokes equations based on Reynolds Stress
Turbulence Model (RSM). The equations are solved by the Finite-
Volume Method (FVM) and the flow is analyzed in terms of steadystate
(single-phased) conditions. The Shumate experimental findings
were used to test the validity of data. Comparison of the simulation
model with the experimental ones indicated a close proximity
between the flow patterns of the two sets. Effects of the discharge
ratio on separation zone dimensions created in the main-channel
downstream of the confluence indicated an inverse relation, where a
decrease in discharge ratio, will entail an increase in the length and
width of the separation zone. The study also found the model as a
powerful analytical tool in the feasibility study of hydraulic
engineering projects.
Abstract: Participation in sporting activities can lead to injury.
Sport injuries have been widely studied in many sports including the
more extreme categories of aquatic board sports. Kitesurfing is a
relatively new water surface action sport, and has not yet been
widely studied in terms of injuries and stress on the body. The aim of
this study was to get information about which injuries that are most
common among kitesurfing participants, where they occur, and their
causes. Injuries were studied using an international open web
questionnaire (n=206).
The results showed that many respondents reported injuries, in
total 251 injuries to knee (24%), ankle (17%), trunk (16%) and
shoulders (10%), often sustained while doing jumps and tricks
(40%). Among the reported injuries were joint injuries (n=101),
muscle/tendon damages (n=47), wounds and cuts (n=36) and bone
fractures (n=28). Also environmental factors and equipment can
influence the risk of injury, or the extent of injury in a hazardous
situation. Conclusively, the information from this retrospective study
supports earlier studies in terms of prevalence and site of injuries.
Suggestively, this information should be used for to build a
foundation of knowledge about the sport for development of
applications for physical training and product development.
Abstract: The use of hard and brittle material has become
increasingly more extensive in recent years. Therefore processing of
these materials for the parts fabrication has become a challenging
problem. However, it is time-consuming to machine the hard brittle
materials with the traditional metal-cutting technique that uses
abrasive wheels. In addition, the tool would suffer excessive wear as
well. However, if ultrasonic energy is applied to the machining
process and coupled with the use of hard abrasive grits, hard and
brittle materials can be effectively machined. Ultrasonic machining
process is mostly used for the brittle materials. The present research
work has developed models using finite element approach to predict
the mechanical stresses sand strains produced in the tool during
ultrasonic machining process. Also the flow behavior of abrasive
slurry coming out of the nozzle has been studied for simulation using
ANSYS CFX module. The different abrasives of different grit sizes
have been used for the experimentation work.
Abstract: The research objective of the project and article “The impact of Structural Funds on the growth of competitiveness of Polish agriculture" is to assess competitiveness of regions in Poland from the perspective of Polish agriculture by analysing the efficiency of the use of Structural Funds, the economic procedure of their distribution and the regulatory and organisational framework under the Rural Development Programme (RDP). It must be stressed that defining the scope of research in the above manner limits the analysis only to the part of Structural Funds directed to support Polish agriculture.
Abstract: This paper looks into detailed investigation of
thermal-hydraulic characteristics of the flow field in a fuel rod
model, especially near the spacer. The area investigate represents a
source of information on the velocity flow field, vortex, and on the
amount of heat transfer into the coolant all of which are critical for
the design and improvement of the fuel rod in nuclear power plants.
The flow field investigation uses three-dimensional Computational
Fluid Dynamics (CFD) with the Reynolds stresses turbulence model
(RSM). The fuel rod model incorporates a vertical annular channel
where three different shapes of spacers are used; each spacer shape is
addressed individually. These spacers are mutually compared in
consideration of heat transfer capabilities between the coolant and
the fuel rod model. The results are complemented with the calculated
heat transfer coefficient in the location of the spacer and along the
stainless-steel pipe.
Abstract: It is known that the heart interacts with and adapts to
its venous and arterial loading conditions. Various experimental
studies and modeling approaches have been developed to investigate
the underlying mechanisms. This paper presents a model of the left
ventricle derived based on nonlinear stress-length myocardial
characteristics integrated over truncated ellipsoidal geometry, and
second-order dynamic mechanism for the excitation-contraction
coupling system. The results of the model presented here describe the
effects of the viscoelastic damping element of the electromechanical
coupling system on the hemodynamic response. Different heart rates
are considered to study the pacing effects on the performance of the
left-ventricle against constant preload and afterload conditions under
various damping conditions. The results indicate that the pacing
process of the left ventricle has to take into account, among other
things, the viscoelastic damping conditions of the myofilament
excitation-contraction process.
Abstract: The incidence of mechanical fracture of an
automobile piston rings prompted development of fracture analysis
method on this case. The three rings (two compression rings and one
oil ring) were smashed into several parts during the power-test (after
manufacturing the engine) causing piston and liner to be damaged.
The radial and oblique cracking happened on the failed piston rings.
The aim of the fracture mechanics simulations presented in this paper
was the calculation of particular effective fracture mechanics
parameters, such as J-integrals and stress intensity factors. Crack
propagation angles were calculated as well. Two-dimensional
fracture analysis of the first compression ring has been developed in
this paper using ABAQUS CAE6.5-1 software. Moreover, SEM
fractography was developed on fracture surfaces and is discussed in
this paper. Results of numerical calculations constitute the basis for
further research on real object.
Abstract: Superplastic deformation and high temperature load
relaxation behavior of coarse-grained iron aluminides with the
composition of Fe-28 at.% Al have been investigated. A series of load
relaxation and tensile tests were conducted at temperatures ranging
from 600 to 850oC. The flow curves obtained from load relaxation
tests were found to have a sigmoidal shape and to exhibit stress vs.
strain rate data in a very wide strain rate range from 10-7/s to 10-2/s.
Tensile tests have been conducted at various initial strain rates ranging
from 3×10-5/s to 1×10-2/s. Maximum elongation of ~500 % was
obtained at the initial strain rate of 3×10-5/s and the maximum strain
rate sensitivity was found to be 0.68 at 850oC in binary Fe-28Al alloy.
Microstructure observation through the optical microscopy (OM) and
the electron back-scattered diffraction (EBSD) technique has been
carried out on the deformed specimens and it has revealed the
evidences for grain boundary migration and grain refinement to occur
during superplastic deformation, suggesting the dynamic
recrystallization mechanism. The addition of Cr by the amount of 5
at.% appeared to deteriorate the superplasticity of the binary iron
aluminide. By applying the internal variable theory of structural
superplasticity, the addition of Cr has been revealed to lower the
contribution of the frictional resistance to dislocation glide during high
temperature deformation of the Fe3Al alloy.
Abstract: In the other to Study of drought stress and Selenium
spraying effect on superoxide dismotase (SOD) activity of rapeseed
(Brassica napus L.) cultivars in Shahr-e-Rey region, an experiment
carried out in Split factorial design in the basis of randomized
complete blocks with 4 replications in 2006. Irrigation in two levels:
Normal irrigation and irrigation with drought stress when the soil
electrical conductivity reached to 60 as main factor and rapeseed
cultivars in 3 levels Zarfam, Okapi, Opera and selenium spraying at
the beginning of flowering stage in 3 levels: 0, 16 and 21 g/ha as sub
factor.
The results showed that the simple and interaction effect of
irrigation, selenium and cultivars on SOD activity had significant
difference. In this case Zarfam cultivar with 2010 u.mg-1 protein and
Opera with 1454 u.mg-1 protein produced maximum and minimum
amounts of SOD activitiy. Interaction effect of irrigation and variety
showed that, normal irrigation in Opera with 1115 u.mg-1 protein
and drought stress in Zarfam with 2784 u.mg-1 protein conducted to
and minimum and maximum amounts of SOD activity.
Interaction effect of irrigation, cultivar and selenium on SOD
indicated that drought stress condition and 21 gr/ha selenium
spraying in Zarfam variety with 3146 u.mg-1 protein gained to
highest activities of SOD.
Abstract: In this paper fatigue crack growth behavior of
aeronautical aluminum alloy 2024 T351 was studied. Effects of
various loading and geometrical parameters are studied such as stress
ratio, amplitude loading, etc. The fatigue crack growth with constant
amplitude is studied using the AFGROW code when NASGRO
model is used. The effect of the stress ratio is highlighted, where one
notices a shift of the curves of crack growth. The comparative study
between two orientations L-T and T-L on fatigue behavior are
presented and shows the variation on the fatigue life. L-T orientation
presents a good fatigue crack growth resistance. Effects of crack
closure are shown in Paris domain and that no crack closure
phenomenons are present at high stress intensity factor.
Abstract: Thermal behavior of fuel channel under loss of coolant accident (LOCA) is a major concern for nuclear reactor safety. LOCA along with failure of emergency cooling water system (ECC) may leads to mechanical deformations like sagging and ballooning. In order to understand the phenomenon an experiment has been carried out using 19 pin fuel element simulator. Main purpose of the experiment was to trace temperature profiles over the pressure tube, calandria tube and clad tubes of Indian Pressurized Heavy Water Reactor (IPHWR) under symmetrical and asymmetrical heat-up conditions. For simulating the fully voided scenario, symmetrical heating of pressure was carried out by injecting 13.2 KW (2 % of nominal power) to all the 19 pins and the temperatures of pressure tube, calandria tube and clad tubes were measured. During symmetrical heating the sagging of fuel channel was initiated at 460 °C and the highest temperature attained by PT was 650 °C . The decay heat from clad tubes was dissipated to moderator mainly by radiation and natural convection. The highest temperature of 680 °C was observed over the outer ring of clad tubes of fuel simulator. Again, to simulate partially voided condition, asymmetrical heating of pressure was carried out by supplying 8.0 kW power to upper 8 pins of fuel simulator and temperature profiles were measured. Along the circumference of pressure tube (PT) the highest temperature difference of 320 °C was observed, which highlights the magnitude of thermal stresses under partially voided conditions.
Abstract: This paper presents a 24 watts SEPIC converter design
and control using microprocessor. SEPIC converter has advantages of
a wide input range and miniaturization caused by the low stress at
elements. There is also an advantage that the input and output are
isolated in MOSFET-off state. This paper presents the PID control
through the SEPIC converter transfer function using a DSP and the
protective circuit for fuel cell from the over-current and
inverse-voltage by using the characteristic of SEPIC converter. Then it
derives them through the experiments.
Abstract: Renewable natural fibres such as oil palm, flax, and
pineapple leaf can be utilized to obtain new high performance
polymer materials. The reuse of waste natural fibres as reinforcement
for polymer is a sustainable option to the environment. However, due
to its high hydroxyl content of cellulose, natural fibres are
susceptible to absorb water that affects the composite mechanical
properties adversely. Research found that Nano materials such as
Nano Silica Carbide (n-SiC) and Nano Clay can be added into the
polymer composite to overcome this problem by enhancing its
mechanical properties in wet condition. The addition of Nano
material improves the tensile and wear properties, flexural stressstrain
behaviour, fracture toughness, and fracture strength of polymer
natural composites in wet and dry conditions.
Abstract: The mechanism behind the electromigration and
thermomigration failure in flip-chip solder joints with Cu-pillar bumps
was investigated in this paper through using finite element method.
Hot spot and the current crowding occurrs in the upper corner of
copper column instead of solders of the common solder ball. The
simulation results show that the change in thermal gradient is
noticeable, which might greatly affect the reliability of solder joints
with Cu-pillar bumps under current stressing. When the average
applied current density is increased from 1×104 A/cm2 to 3×104 A/cm2
in solders, the thermal gradient would increase from 74 K/cm to 901
K/cm at an ambient temperature of 25°C. The force from thermal
gradient of 901 K/cm can nearly induce thermomigration by itself.
With the increase in applied current, the thermal gradient is growing. It
is proposed that thermomigration likely causes a serious reliability
issue for Cu column based interconnects.
Abstract: In this survey the process of crack propagation at the
toe of concrete gravity dam is investigated by applying principals
and criteria of linear elastic fracture mechanic. Simulating process of
earthquake conditions for three models of dam with different
geometrical condition, in empty reservoir under plain stress is
calculated through special fracture mechanic software FRANNC2D
[1] for determining fracture mechanic criteria. The outcomes showed
that in spite of the primary expectations, the simultaneous existence
of fillet in both toe and heel area (model 3), the rate of maximum
principal stress has not been decreased; however, even the maximum
principal stress has increased, so it caused stress intensity factors
increase which is undesirable. On the other hand, the dam with heel
fillet has shown the best attitude and it is because of items like
decreasing the rates of maximum and minimum principal stresses and
also is related to decreasing the rates of stress intensity factors for 1st
& 2nd modes of the model.
Abstract: In this study, stress distributions on dental implants
made of functionally graded biomaterials (FGBM) are investigated
numerically. The implant body is considered to be subjected to axial
compression loads. Numerical problem is assumed to be 2D, and
ANSYS commercial software is used for the analysis. The cross
section of the implant thread varies as varying the height (H) and the
width (t) of the thread. According to thread dimensions of implant
and material properties of FGBM, equivalent stress distribution on
the implant is determined and presented with contour plots along
with the maximum equivalent stress values. As a result, with
increasing material gradient parameter (n), the equivalent stress
decreases, but the minimum stress distribution increases. Maximum
stress values decrease with decreasing implant radius (r). Maximum
von Mises stresses increases with decreasing H when t is constant.
On the other hand, the stress values are not affected by variation of t
in the case of H = constant.
Abstract: This study investigates the relationships between
Work Motivation, Work Stress, and Job Satisfaction toward
cross-strait employees. The target subjects are three
manufacturing firms in Mainland China and Taiwan. Out of 450
distributed surveys, 352 valid surveys were obtained with the
response rate of 78.22%.The findings have addressed three main
pull factors toward cross-strait employees in choosing jobs, which
are (1) high level of firm stability, (2) good firm image, and (3)
good employee benefits. In addition, various employee attributes
exert different impacts on Work Motivation, Work Stress, and
Job Satisfaction. The comparison between expected and actual
perceived Job Satisfaction toward cross-strait employees shows
that “salary" ranks highest regarding expected Job Satisfaction
whereas “co-worker relationship" ranks highest regarding actual
perceived Job Satisfaction, which implies actual perceived Job
Satisfaction do not match employee expectations. Therefore, this
research further concludes that there exists differences between
employees- expected and actual perceived Job Satisfaction.
Abstract: Analytical procedure was carried out in this paper to
calculate the ultimate load capacity of reinforced concrete corbels
strengthened or repaired externally with CFRP sheets. Strut and tie
method and shear friction method proposed earlier for analyzing
reinforced concrete corbels were modified to incorporate the effect of
external CFRP sheets bonded to the corbel. The points of weakness
of any method that lead to an inaccuracy, especially when
overestimating test results were checked and discussed. Comparison
of prediction with the test data indicates that the ratio of test /
calculated ultimate load is 0.82 and 1.17 using strut and tie method
and shear friction method, respectively. If the limits of maximum
shear stress is followed, the calculated ultimate load capacity using
shear friction method was found to underestimates test data
considerably.
Abstract: Perennial ryegrass (Lolium perenne L.) plants are cultivated for lawn constitution and as forage plants. Considerable number of perennial ryegrass genotypes are present in the flora of our country and they present substantial was performed based on a Project supported bu TUBITAK (Project numver : 106O159) and perannial ryegrass genotypes from 8 provinces were collected during 2006. Seeds of perennial ryegrass were collected from 48 different locations. Populations of turfgrass seeds in flowerpots to be 20 and 1 cm deep greenhouse were sown in three replications at 07.07.2007.Then the growth of turfgrass seedlings in the greenhouse in pots showed sufficiently separated from the plants were planted in each population. Plants planted in the garden of the observation scale of 1-9 was evaluated by the quality, 1 = the weakest / worst, 6 = acceptable and 9 = superior or considered as an ideal. Essentially only recognized in assessing the quality of the color of grass, but the color, density, uniformity, texture (texture), illness or environmental stresses are evaluated as a combination reaction. Turfgrass quality 15.11.2007, 19.03.2008, 27.05.2008, 27.11.2008, 07.03.2009 and 02.06.2009 have been 6 times to be in order. Observations made regarding the quality of grass; 3 years according to seasonal environments turf quality genotypes belonging to 14 different populations were found to be 7.5 and above are reserved for future use in breeding works.The number of genotypes belonging to 41 populations in terms of turfgrass quality was determined as 7.9 of 3 year average seasonal. Argıthan between Doğanhisar (Konya) is located 38.09 latitude and 31.40 longitude, altitude 1158 m in the set that population numbered 41.