Abstract: This paper presents a hybrid three phase rectifier for
high power factor application. This rectifier is composed by zero
voltage transition (ZVT) and zero current transition (ZCT) boost
converter with three phase diode bridge rectifier, in parallel with a six
pulse three phase pulse width modulation (PWM) controlled rectifier.
The proposed topology is capable of high power factor with DC
output voltage regulation by providing sinusoidal input. Also, it
increases the overall efficiency of the new hybrid rectifier to 94.56%
and the total harmonic distortion of the hybrid structure varies from
0% to 16% at nominal output power. This topology was simulated in
MATLAB/SIMULINK environment and the output waveforms
presented with experimental result.
Abstract: Artemisia species, which are medically beneficial, are
widespread in temperate regions of both Northern and Southern
hemispheres among which Iran is located. About 35 species of
Artemisia are indigenous in Iran among them some are widespread in
all or most provinces, yet some are restricted to some specific
regions. In this review paper, initially, GC-Mass results of some
experiments done in different provinces of Iran are mentioned among
them some compounds are common among species, some others are
mostly restricted to other species; after that, medical advantages
based on some researches on species of this genus are reviewed;
different qualities such as anti-leishmania, anti-bacteria, antiviral as
well as anti-proliferative could be mentioned.
Abstract: The aim of the paper was to elaborate a novel calculator BasWilCalc, that allows to estimate the actual amount of biomass on the basket willow plantations. The proposed method is based on the results of field experiment conducted during years 2011-2013 on basket willow plantation in the south-western part of Poland. As input data the results of destructive measurements of the diameter, length and weight of willow stems and non-destructive biometric measurements of diameter in the middle of stems and their length during the growing season performed at weekly intervals were used. Performed analysis enabled to develop the algorithm which, due to the fact that energy plantations are of known and constant planting structure, allows to estimate the actual amount of willow basket biomass on the plantation with a given probability and accuracy specified by the model, based on the number of stems measured and the age of the plantation.
Abstract: Copper being one of the major intrinsic residual
impurities in steel possesses the tendency to induce severe
microstructural distortions if not controlled within certain limits.
Hence, this paper investigates the effect of this element on the
mechanical properties of construction steel with a view to ascertain
its safe limits for effective control. The experiment entails collection
of statistically scheduled samples of hot rolled profiles with varied
copper concentrations in the range of 0.12-0.39 wt. %. From these
samples were prepared standard test specimens subjected to tensile,
impact, hardness and microstructural analyses. Results show a rather
huge compromise in mechanical properties as the specimens
demonstrated 54.3%, 74.2% and 64.9% reduction in tensile strength,
impact energy and hardness respectively as copper content increases
from 0.12 wt. % to 0.39 wt. %. The steel’s abysmal performance is
due to the severe distortion of the microstructure occasioned by the
development of incoherent complex compounds which weaken the
pearlite reinforcing phase. It is concluded that the presence of copper
above 0.22 wt. % is deleterious to construction steel performance.
Abstract: Mass flow measurement is the basis of most technoeconomic
formulations in the chemical industry. This calls for
reliable and accurate detection of mass flow. Flow measurement
laboratory experiments were conducted using various instruments.
These consisted of orifice plates, various sized rotameters, wet gas
meter and soap bubble meter. This work was aimed at evaluating
appropriate operating conditions and accuracy of the aforementioned
devices. The experimental data collected were compared to
theoretical predictions from Bernoulli’s equation and calibration
curves supplied by the instrument’s manufacturers. The results
obtained showed that rotameters were more reliable for measuring
high and low flow rates; while soap-bubble meters and wet-gas
meters were found to be suitable for measuring low flow rates. The
laboratory procedures and findings of the actual work can assist
engineering students and professionals in conducting their flow
measurement laboratory test work.
Abstract: In this work, we propose the application of Japanese
“Origami” art for a floating function of a small aerial vehicle such as a
hexarotor. A preliminary experiment was conducted using Origami
magic balls mounted under a hexarotor. This magic ball can expand
and shrink using an air pump during free flying. Using this interesting
and functional concept, it promises to reduce the resistance of wind as
well as reduce the energy consumption when the Origami balls are
deflated. This approach can be particularly useful in rescue emergency
situations. Furthermore, there are many unexpected reasons that may
cause the multi-rotor has to land on the surface of water due to
problems with the communication between the aircraft and the ground
station. In addition, a complementary experiment was designed to
prove that the hexarotor can fly maintaining the stability and also,
takes off and lands on the surface of water using air balloons.
Abstract: This entry concerned with dense silica bricks
microstructure was produced as a part of a project within the
Technology Agency of the Czech Republic which is being
implemented in cooperation of the biggest producer of refractories
the P-D Refractories CZ company with the research organisation
Brno University of Technology. The paper is focused on the
influence of mixture homogenisation and the influence of grain size
of the mineraliser on the resulting utility properties of the material as
well as its microstructure. It has a decisive influence on the durability
of the material in a building structure. This paper is a continuation of
a previously published study dealing with the suitability of various
types of mineralising agents in terms of density, strength and mineral
composition of silica brick.
The entry describes the influence of the method of mixture
homogenisation and the influence of granulometry of the applied Femineralising
agent on the resulting silica microstructure. Porosity,
density, phase composition and microstructure of the experimentally
prepared silica bricks samples were examined and the results were
discussed in context with the technology of homogenisation and
firing temperature used. The properties of silica bricks samples were
compared to the sample without any Fe-mineraliser.
Abstract: Load carrying capacity of an oil lubricated two-axial
groove journal bearing is simulated by taking into account the
viscosity variations in lubricant due to the addition of TiO2
nanoparticles as lubricant additive. Shear viscosities of TiO2
nanoparticle dispersions in oil are measured for various nanoparticle
additive concentrations. The viscosity model derived from the
experimental viscosities is employed in a modified Reynolds
equation to obtain the pressure profiles and load carrying capacity of
two-axial groove journal bearing. Results reveal an increase in load
carrying capacity of bearings operating on nanoparticle dispersions as
compared to plain oil.
Abstract: The study deals with the challenges in developing a
test rig to test the performance of water lubricated journal bearing.
The test rig is designed to simulate the working conditions of the
bearing in order to understand their performance before they are put
in operation. The bearing that is studied is the commercially available
water lubricated bearing which has a rubber liner bonded with a rigid
metal shell. The lubricant enters the bearing axially through a
pressurized inlet tank and exits to an outlet tank which is at
sufficiently low pressure. The load on the bearing is applied through
the dead weight system which acts both in upward and downward
direction so that net load acts on the bearing. The issues in feeding
the lubricant into the bearing from the inlet side and preventing the
leakage of the lubricant is discussed. The application of the load on
the test bearing while maintaining the bearing afloat is also discussed.
Abstract: Chloride resistance in Ultra High Performance
Concrete (UHPC) is determined in this paper. This work deals with
the one dimension chloride transport, which can be potentially
dangerous particularly for the durability of concrete structures. Risk
of reinforcement corrosion due to exposure to the concrete surface to
direct the action of chloride ions (mainly in the form de-icing salts or
groundwater) is dangerously increases. The measured data are
investigated depending on the depth of penetration of chloride ions
into the concrete structure. Comparative measurements with normal
strength concrete are done as well. The experimental results showed
that UHCP have improved resistance of chlorides penetration than
NSC and also chloride diffusion depth is significantly lower in
UHCP.
Abstract: The use of permanent magnets (PM) is increasing in
permanent magnet synchronous machines (PMSM) to fulfill the
requirements of high efficiency machines in modern industry. PMSM
are widely used in industrial applications, wind power plants and the
automotive industry. Since PMSM are used in different
environmental conditions, the long-term effect of NdFeB-based
magnets at high temperatures and their corrosion behavior have to be
studied due to the irreversible loss of magnetic properties.
In this paper, the effect of magnetic properties due to corrosion
and increasing temperature in a climatic chamber has been presented.
The magnetic moment and magnetic field of the magnets were
studied experimentally.
Abstract: In this study, the evaluation of thermal stability of the
micrometer-sized silica particle reinforced epoxy composite was
carried out through the measurement of thermal expansion coefficient
and Young’s modulus of the specimens. For all the specimens in this
study from the baseline to those containing 50 wt% silica filler, the
thermal expansion coefficients and the Young’s moduli were
gradually decreased down to 20% and increased up to 41%,
respectively. The experimental results were compared with fillervolume-
based simple empirical relations. The experimental results of
thermal expansion coefficients correspond with those of Thomas’s
model which is modified from the rule of mixture. However, the
measured result for Young’s modulus tends to be increased slightly.
The differences in increments of the moduli between experimental and
numerical model data are quite large.
Abstract: In this study, a three dimensional numerical heat
transfer model has been used to simulate the laser structuring of
polymer substrate material in the Three-Dimensional Molded
Interconnect Device (3D MID) which is used in the advanced multifunctional
applications. A finite element method (FEM) transient
thermal analysis is performed using APDL (ANSYS Parametric
Design Language) provided by ANSYS. In this model, the effect of
surface heat source was modeled with Gaussian distribution, also the
effect of the mixed boundary conditions which consist of convection
and radiation heat transfers have been considered in this analysis. The
model provides a full description of the temperature distribution, as
well as calculates the depth and the width of the groove upon material
removal at different set of laser parameters such as laser power and
laser speed. This study also includes the experimental procedure to
study the effect of laser parameters on the depth and width of the
removal groove metal as verification to the modeled results. Good
agreement between the experimental and the model results is
achieved for a wide range of laser powers. It is found that the quality
of the laser structure process is affected by the laser scan speed and
laser power. For a high laser structured quality, it is suggested to use
laser with high speed and moderate to high laser power.
Abstract: In order to investigate the effect of Plant Growth
Promoting Rhizobacteria (PGPR) and rhizobium bacteria on grain
yield and some agronomic traits of mungbean (Vigna radiate L.), an
experiment was carried out based on randomized complete block
design with three replications in Malekshahi, Ilam province, Iran
during 2012-2013 cropping season. Experimental treatments
consisted of control treatment, inoculation with rhizobium bacteria,
rhizobium bacteria and Azotobacter, rhizobium bacteria and
Azospirillum, rhizobium bacteria and Pseudomonas, rhizobium
bacteria, Azotobacter and Azospirillum, rhizobium bacteria,
Azotobacter and Pseudomonas, rhizobium bacteria, Azospirillum and
Pseudomonas and rhizobium bacteria, Azotobacter, Azospirillum and
Pseudomonas. The results showed that the effect of PGPR and
rhizobium bacteria were significant affect on grain and its
components in mungbean plant. Grain yield significantly increased
by PGPR and rhizobium bacteria, so that the maximum grain yield
was obtained from rhizobium bacteria + Azospirillum +
Pseudomonas with the amount of 2287 kg.ha-1 as compared to
control treatment. Excessive application of chemical fertilizers causes
environmental and economic problems. That is, the overfertilization
of P and N leads to pollution due to soil erosion and runoff water, so
the use of PGPR and rhizobium bacteria can be justified due to
reduce input costs, increase in grain yield and environmental friendly.
Abstract: Voltage sags are the most common power quality
disturbance in the distribution system. It occurs due to the fault in the
electrical network or by the starting of a large induction motor and
this can be solved by using the custom power devices such as
Dynamic Voltage Restorer (DVR). In this paper DVR is proposed to
compensate voltage sags on critical loads dynamically. The DVR
consists of VSC, injection transformers, passive filters and energy
storage (lead acid battery). By injecting an appropriate voltage, the
DVR restores a voltage waveform and ensures constant load voltage.
The simulation and experimental results of a DVR using MATLAB
software shows clearly the performance of the DVR in mitigating
voltage sags.
Abstract: Malathion (ML) is a well known pesticide commonly
used in many agricultural and non-agricultural processes. Its toxicity
has been attributed primarily to the accumulation of acetylcholine
(Ach) at nerve junctions, due to the inhibition of acetylcholinesterase
(AChE). The aim of the current research was to study the protective
effect of the melissa plant extract against reproductive impairment
induced by malathion in 32 male albino rats, and the biological
experiment was divided into four groups (8 in each) that given
malathion (27 mg/kg; 1/50 of the LD50 for an oral dose) and/or
Melissa officinalis (MO) extract (200mg/kg/day) by gavages
technique. The sperm counts, sperm motility, sperm morphology,
FSH, LH, and testosterone levels had been determined in testes
homogenate at the end of the experiment. It is worthy to report that,
rats treated with melissa extract did not show a significant difference
when compared with the control group, while rats given malathion
alone had significantly lower sperm count, sperm motility, and
significantly higher abnormal sperm numbers, than the untreated
control rats as well as having significantly lower serum FSH, LH, and
testosterone levels compared with the control group. Administrations
of melissa extract restore all mentioned histological parameters
towards the control group and the melissa extract had a strong
positive protective effect against malathion toxicity. Results the of
biological parameters were confirmed by the histological
examination of rat testes and indicated that, both control and melissa
groups showing normal seminiferous tubules, while malathion group
testicular tissues had necrosis, edema in the seminiferous tubules and
degeneration of spermatogonial cells lining the seminiferous tubules
with incomplete spermatogenesis. The use of melissa against
malathion improved the histological picture and showing normal
seminiferous tubules with complete spermatogenesis and almost there
was no histopathological changes could be noted.
Abstract: The most important part of modern lean low NOx combustors is a premixer where swirlers are often used for intensification of mixing processes and further formation of required flow pattern in combustor liner. Swirling flow leads to formation of complex eddy structures causing flow perturbations. It is able to cause combustion instability. Therefore, at design phase, it is necessary to pay great attention to aerodynamics of premixers. Analysis based on unsteady CFD modeling of swirling flow in production combustor swirler showed presence of large number of different eddy structures that can be conditionally divided into three types relative to its location of origin and a propagation path. Further, features of each eddy type were subsequently defined. Comparison of calculated and experimental pressure fluctuations spectrums verified correctness of computations.
Abstract: Composite materials have important assets compared
to traditional materials. They bring many functional advantages:
lightness, mechanical resistance and chemical, etc. In the present
study we examine the effect of a circular central notch and a precrack
on the tensile fracture of two woven composite materials. The tensile
tests were applied to a standardized specimen, notched and a
precarcked (orientation of the crack 0°, 45° and 90°). These tensile
tests were elaborated according to an experimental planning design of
the type 23.31 requiring 24 experiments with three repetitions. By the
analysis of regression, we obtained a mathematical model describing
the maximum load according to the influential parameters (hole
diameter, precrack length, angle of a precrack orientation). The
specimens precracked at 90° have a better behavior than those having
a precrack at 45° and still better than those having of the precracks
oriented at 0°. In addition the maximum load is inversely
proportional to the notch size.
Abstract: The paper describes the experiments and the kinetic
parameters calculus of the gasoil hydrofining. They are presented
experimental results of gasoil hidrofining using Mo and promoted
with Ni on aluminum support catalyst. The authors have adapted a
kinetic model gasoil hydrofining. Using this proposed kinetic model
and the experimental data they have calculated the parameters of the
model. The numerical calculus is based on minimizing the difference
between the experimental sulf concentration and kinetic model
estimation.
Abstract: In this paper we make a temperature investigations in
two type of superposed crimped connections using experimental
determinations. All the samples use 8 copper wire 7.1 x 3 mm2
crimped by two methods: the first method uses one crimp indents and
the second is a proposed method with two crimp indents. The ferrule
is a parallel one. We study the influence of number and position of
crimp indents. The samples are heated in A.C. current at different
current values until steady state heating regime. After obtaining of
temperature values, we compare them and present the conclusion.