Abstract: The transient thermoelastic response of thick hollow cylinder made of functionally graded material under thermal loading is studied. The generalized coupled thermoelasticity based on the Green-Lindsay model is used. The thermal and mechanical properties of the functionally graded material are assumed to be varied in the radial direction according to a power law variation as a function of the volume fractions of the constituents. The thermal and elastic governing equations are solved by using Galerkin finite element method. All the finite element calculations were done by using commercial finite element program FlexPDE. The transient temperature, radial displacement, and thermal stresses distribution through the radial direction of the cylinder are plotted.
Abstract: Addition of milli or micro sized particles to the heat
transfer fluid is one of the many techniques employed for improving
heat transfer rate. Though this looks simple, this method has
practical problems such as high pressure loss, clogging and erosion
of the material of construction. These problems can be overcome by
using nanofluids, which is a dispersion of nanosized particles in a
base fluid. Nanoparticles increase the thermal conductivity of the
base fluid manifold which in turn increases the heat transfer rate.
Nanoparticles also increase the viscosity of the basefluid resulting in
higher pressure drop for the nanofluid compared to the base fluid. So
it is imperative that the Reynolds number (Re) and the volume
fraction have to be optimum for better thermal hydraulic
effectiveness. In this work, the heat transfer enhancement using
aluminium oxide nanofluid using low and high volume fraction
nanofluids in turbulent pipe flow with constant wall temperature has
been studied by computational fluid dynamic modeling of the
nanofluid flow adopting the single phase approach. Nanofluid, up till
a volume fraction of 1% is found to be an effective heat transfer
enhancement technique. The Nusselt number (Nu) and friction factor
predictions for the low volume fractions (i.e. 0.02%, 0.1 and 0.5%)
agree very well with the experimental values of Sundar and Sharma
(2010). While, predictions for the high volume fraction nanofluids
(i.e. 1%, 4% and 6%) are found to have reasonable agreement with
both experimental and numerical results available in the literature.
So the computationally inexpensive single phase approach can be
used for heat transfer and pressure drop prediction of new nanofluids.
Abstract: The aim of this in vitro study was to evaluate the possible interference of a Nectandra membranacea extract (i) on the labeling of blood cells (BC), (ii) on the labeling process of BC and plasma (P) proteins with technetium-99m (Tc-99m) and (iii) on the morphology of red blood cells (RBC). Blood samples were incubated with a Nectandra membranacea crude extract, stannous chloride, Tc- 99m (sodium pertechnetate) was added, and soluble (SF) and insoluble (IF) fractions were isolated. Morphometry studies were performed with blood samples incubated with Nectandra membranacea extract. The results show that the Nectandra membranacea extract does not promote significant alteration of the labeling of BC, IF-P and IF-BC. The Nectandra membranacea extract was able to alter the erythrocyte membrane morphology, but these morphological changes were not capable to interfere on the labeling of blood constituents with Tc-99m.
Abstract: It was analyzed of fatty acid composition of 16 strains
of microalgae lipid fractions isolated from different basins of
Kazakhstan and characterized by stable active growth in the
laboratory. Three species of green microalgae (Oocystis
rhomboideus, Chlorococcum infusionum, Dictyochlorella globosa)
and three species of diatoms (Synedra sp., Nitzshia sp., Pleurosigma
attenuatum) are characterized by a high content of lipids and are
promising for further study as a source of polyunsaturated fatty acids.
Abstract: We investigated the response of testosterone (T),
growth hormone (GH), cortisol (C), steroid hormone binding
globulin (SHBG), insulin-like growth factor (IGF-1), insulin-like
growth factor binding protein-3 (IGFBP-3), and some anaboliccatabolic
indexes, i.e.: T/C, T/SHBG, and IGF-1/IGFBP-3 to
maximal exercise in endurance-trained athletes (TREN) and
untrained subjects (CG). The baseline concentration of IGF-1 was
higher in athletes (TREN) when compared to the CG (p
Abstract: Study is on the vibration of thin cylindrical shells made of a functionally gradient material (FGM) composed of stainless steel and nickel is presented. The effects of the FGM configuration are studied by studying the frequencies of FG cylindrical shells. In this case FG cylindrical shell has Nickel on its inner surface and stainless steel on its outer surface. The study is carried out based on third order shear deformation shell theory. The objective is to study the natural frequencies, the influence of constituent volume fractions and the effects of configurations of the constituent materials on the frequencies. The properties are graded in the thickness direction according to the volume fraction power-law distribution. Results are presented on the frequency characteristics, the influence of the constituent various volume fractions on the frequencies.
Abstract: Long terms variation of solar insolation had been
widely studied. However, its parallel observations in short time scale
is rather lacking. This paper aims to investigate the short time scale
evolution of solar radiation spectrum (UV, PAR, and NIR bands) due
to atmospheric aerosols and water vapors. A total of 25 days of
global and diffused solar spectrum ranges from air mass 2 to 6 were
collected using ground-based spectrometer with shadowband
technique. The result shows that variation of solar radiation is the
least in UV fraction, followed by PAR and the most in NIR. Broader
variations in PAR and NIR are associated with the short time scale
fluctuations of aerosol and water vapors. The corresponding daily
evolution of UV, PAR, and NIR fractions implies that aerosol and
water vapors variation could also be responsible for the deviation
pattern in the Langley-plot analysis.
Abstract: In this study, a 3D combustion chamber was simulated
using FLUENT 6.32. Aims to obtain accurate information about the
profile of the combustion in the furnace and also check the effect of
oxygen enrichment on the combustion process. Oxygen enrichment is
an effective way to reduce combustion pollutant. The flow rate of air
to fuel ratio is varied as 1.3, 3.2 and 5.1 and the oxygen enriched
flow rates are 28, 54 and 68 lit/min. Combustion simulations
typically involve the solution of the turbulent flows with heat
transfer, species transport and chemical reactions. It is common to
use the Reynolds-averaged form of the governing equation in
conjunction with a suitable turbulence model. The 3D Reynolds
Averaged Navier Stokes (RANS) equations with standard k-ε
turbulence model are solved together by Fluent 6.3 software. First
order upwind scheme is used to model governing equations and the
SIMPLE algorithm is used as pressure velocity coupling. Species
mass fractions at the wall are assumed to have zero normal
gradients.Results show that minimum mole fraction of CO2 happens
when the flow rate ratio of air to fuel is 5.1. Additionally, in a fixed
oxygen enrichment condition, increasing the air to fuel ratio will
increase the temperature peak. As a result, oxygen-enrichment can
reduce the CO2 emission at this kind of furnace in high air to fuel
rates.
Abstract: This paper presents a novel template-based method to
detect objects of interest from real images by shape matching. To
locate a target object that has a similar shape to a given template
boundary, the proposed method integrates three components: contour
grouping, partial shape matching, and boundary verification. In the
first component, low-level image features, including edges and
corners, are grouped into a set of perceptually salient closed contours
using an extended ratio-contour algorithm. In the second component,
we develop a partial shape matching algorithm to identify the
fractions of detected contours that partly match given template
boundaries. Specifically, we represent template boundaries and
detected contours using landmarks, and apply a greedy algorithm to
search the matched landmark subsequences. For each matched
fraction between a template and a detected contour, we estimate an
affine transform that transforms the whole template into a hypothetic
boundary. In the third component, we provide an efficient algorithm
based on oriented edge lists to determine the target boundary from
the hypothetic boundaries by checking each of them against image
edges. We evaluate the proposed method on recognizing and
localizing 12 template leaves in a data set of real images with clutter
back-grounds, illumination variations, occlusions, and image noises.
The experiments demonstrate the high performance of our proposed
method1.
Abstract: In the present study, the pressure drop and laminar convection heat transfer characteristics of nanofluids in microchannel heat sink with square duct are numerically investigated. The water based nanofluids created with Al2O3 and CuO particles in four different volume fractions of 0%, 0.5%, 1%, 1.5% and 2% are used to analyze their effects on heat transfer and the pressure drop. Under the laminar, steady-state flow conditions, the finite volume method is used to solve the governing equations of heat transfer. Mixture Model is considered to simulate the nanofluid flow. For verification of used numerical method, the results obtained from numerical calculations were compared with the results in literature for both pure water and the nanofluids in different volume fractions. The distributions of the particles in base fluid are assumed to be uniform. The results are evaluated in terms of Nusselt number, the pressure drop and heat transfer enhancement. Analysis shows that the nanofluids enhance heat transfer while the Reynolds number and the volume fractions are increasing. The best overall enhancement was obtained at φ=%2 and Re=100 for CuO-water nanofluid.
Abstract: Five lignin samples were fractionated with
Acetone/Water mixtures and the obtained fractions were subjected to
extensive structural characterization, including Fourier Transform
Infrared (FT-IR), Gel permeation Chromatography (GPC) and
Phosphorus-31 NMR spectroscopy (31P-NMR). The results showed
that for all studied lignins the solubility increases with the increment
of the acetone concentration. Wheat straw lignin has the highest
solubility in 90/10 (v/v) Acetone/Water mixture, 400 mg lignin being
dissolved in 1 mL mixture. The weight average molecular weight of
the obtained fractions increased with the increment of acetone
concentration and thus with solubility. 31P-NMR analysis based on
lignin modification by reactive phospholane into phosphitylated
compounds was used to differentiate and quantify the different types
of OH groups (aromatic, aliphatic, and carboxylic) found in the
fractions obtained with 70/30 (v/v) Acetone/Water mixture.
Abstract: This paper presents the experiment results of investigating the effects of adding various types and proportions of fibre on mechanical strength and permeability characteristics of recycled aggregate concrete (RAC), which was produced with treated coarse recycled concrete aggregate (RCA). Two types of synthetic fibres (i.e., barchip and polypropylene fibre) with various volume fractions were added to the RAC, which was calculated by the weight of the cement. The hardened RAC properties such as compressive strength, flexural strength, ultrasonic pulse velocity, water absorption and total porosity at the curing ages of 7 and 28 days were evaluated and compared with the properties of the control specimens. Results indicate that the treated coarse RCA enhances the mechanical strength and permeability properties of RAC and adding barchip fibre further optimises the results. Adding 1.2% barchip fibre has the best effect on the mechanical strength performance of the RAC.
Abstract: The paper compares the treatment of fractions in a
typical undergraduate college curriculum and in abstract algebra
textbooks. It stresses that the main difference is that the
undergraduate curriculum treats equivalent fractions as equal, and
this treatment eventually leads to paradoxes and impairs the students-
ability to perceive ratios, proportions, radicals and rational exponents
adequately. The paper suggests a simplified version of rigorous
theory of fractions suitable for regular college curriculum.
Abstract: Leonotisleonurus a shrub indigenous to Southern
Africa is widely used in traditional medicine to treat a variety of
conditions ranging from skin diseases and cough to epileptic fits and
‘heart problems’. Studies on the aqueous extract of the leaves have
indicated cycloxegenase enzyme inhibitory activity and an
antihypertensive effect.
Five methanol leaf extract fractions (MLEa - MLEe) of L.
leonurus were tested on anaesthetized normotensive male Wistar rats
(AWR) and isolated perfused working rat hearts (IWH). Fraction
MLEc (0.01mg/kg – 0.05mg/kg) induced significant increases in BP
and HR in AWR and positive chronotropic and inotropic effects in
IWH (1.0mg/ml – 5.0mg/ml). Pre-administration of atenolol
(2.0mg/kg) and prazosin (60μg/kg) significantly inhibited MLEc
effect on HR and MAP respectively in vivo, while atenolol
(7.0mg/ml) pre-perfusion significantly inhibited MLEc effect in vitro.
The hypertensive effect of MLEc is probably via β1agonism.
Results also indicate the presence of multiple cardioactive
compounds in L. leonurus.
Abstract: This study was carried out to evaluate concentration
of micro minerals (Zn, Fe, Mn, Cu and Se) of forages and their
distribution in fiber fraction (neutral detergent fiber/NDF and acid
detergent fiber/ADF) in South Sumatra during dry and rainy seasons.
Seven species of commonly forages namely Axonopus compressus,
Panicum maximum, Pennisetum purpuphoides, Leucaena
leucocephala, Centrocema pubescens, Calopogonium mucunoides
and Acacia mangium were collected at native pasture during rainy
and dry seasons. The results showed that micro minerals
concentration of forages and their distribution in fiber fraction varied
among species and season. In general, concentration of micro
minerals was slightly higher in rainy season compared to dry season
either in grass or legumes forages. In grass, concentration of Fe and
Mn were above the critical level, while 33.3 %, 100 % and 16.7 % of
evaluated grass were deficient in Zn, Cu and Se. Data on legume
forages show that 75 % of legumes were deficient in Zn and Mn, 62.5
% deficient in Cu and 50 % deficient in Se. There was no species of
legume deficient in Fe. Distribution of micro minerals in NDF and
ADF were also significantly affected by species and season and
depends on the kinds of element measured. Generally, micro minerals
were associated in fiber fractions much higher during dry season
compared to rainy season. Iron (Fe) and selenium (Se) in forages
were the highest elements associated in NDF and ADF, while the
lowest was found in Copper (Cu).
Abstract: In this study, the thermal and mechanical properties of
basalt fibre reinforced concrete were investigated. The volume
fractions of basalt fibre of (0.1, 0.2, 0.3, and 0.5% by total mix
volume) were used. Properties such as heat transfer, compressive and
splitting tensile strengths were examined. Results indicated that the
strength increases with increase the fibre content till 0.3% then there
is a slight reduction when 0.5% fibre used. Lower amount of heat
conducted through the thickness of concrete specimens than the
conventional concrete was also recorded.
Abstract: This paper presents an exact analytical model for
optimizing stability of thin-walled, composite, functionally graded
pipes conveying fluid. The critical flow velocity at which divergence
occurs is maximized for a specified total structural mass in order to
ensure the economic feasibility of the attained optimum designs. The
composition of the material of construction is optimized by defining
the spatial distribution of volume fractions of the material
constituents using piecewise variations along the pipe length. The
major aim is to tailor the material distribution in the axial direction so
as to avoid the occurrence of divergence instability without the
penalty of increasing structural mass. Three types of boundary
conditions have been examined; namely, Hinged-Hinged, Clamped-
Hinged and Clamped-Clamped pipelines. The resulting optimization
problem has been formulated as a nonlinear mathematical
programming problem solved by invoking the MatLab optimization
toolbox routines, which implement constrained function
minimization routine named “fmincon" interacting with the
associated eigenvalue problem routines. In fact, the proposed
mathematical models have succeeded in maximizing the critical flow
velocity without mass penalty and producing efficient and economic
designs having enhanced stability characteristics as compared with
the baseline designs.
Abstract: This paper investigates experimentally and
analytically the torsion behavior of steel fibered high strength self
compacting concrete beams reinforced by GFRP bars. Steel fibered
high strength self compacting concrete (SFHSSCC) and GFRP bars
became in the recent decades a very important materials in the
structural engineering field. The use of GFRP bars to replace steel
bars has emerged as one of the many techniques put forward to
enhance the corrosion resistance of reinforced concrete structures.
High strength concrete and GFRP bars attract designers and
architects as it allows improving the durability as well as the esthetics
of a construction. One of the trends in SFHSSCC structures is to
provide their ductile behavior and additional goal is to limit
development and propagation of macro-cracks in the body of
SFHSSCC elements. SFHSSCC and GFRP bars are tough, improve
the workability, enhance the corrosion resistance of reinforced
concrete structures, and demonstrate high residual strengths after
appearance of the first crack. Experimental studies were carried out
to select effective fiber contents. Three types of volume fraction from
hooked shape steel fibers are used in this study, the hooked steel
fibers were evaluated in volume fractions ranging between 0.0%,
0.75% and 1.5%. The beams shape is chosen to create the required
forces (i.e. torsion and bending moments simultaneously) on the test
zone. A total of seven beams were tested, classified into three groups.
All beams, have 200cm length, cross section of 10×20cm,
longitudinal bottom reinforcement of 3
Abstract: In order to investigate a PROX microreactor
performance, two-dimensional modeling of the reacting flow
between two parallel plates is performed through a finite volume
method using an improved SIMPLE algorithm. A three-step surface
kinetics including hydrogen oxidation, carbon monoxide oxidation
and water-gas shift reaction is applied for a Pt-Fe/γ-Al2O3 catalyst
and operating temperatures of about 100ºC. Flow pattern, pressure
field, temperature distribution, and mole fractions of species are
found in the whole domain for all cases. Also, the required reactive
length for removing carbon monoxide from about 2% to less than 10
ppm is found. Furthermore, effects of hydraulic diameter, wall
temperature, and inlet mole fraction of air and water are investigated
by considering carbon monoxide selectivity and conversion. It is
found that air and water addition may improve the performance of
the microreactor in carbon monoxide removal in such operating
conditions; this is in agreement with the pervious published results.
Abstract: Recently, content delivery services have grown rapidly
over the Internet. For ASPs (Application Service Provider) providing
content delivery services, P2P architecture is beneficial to reduce
outgoing traffic from content servers. On the other hand, ISPs are
suffering from the increase in P2P traffic. The P2P traffic is
unnecessarily redundant because the same content or the same
fractions of content are transferred through an inter-ISP link several
times. Subscriber ISPs have to pay a transit fee to upstream ISPs based
on the volume of inter-ISP traffic. In order to solve such problems,
several works have been done for the purpose of P2P traffic reduction.
However, these existing works cannot control the traffic volume of a
certain link. In order to solve such an ISP-s operational requirement,
we propose a method to control traffic volume for a link within a
preconfigured upper bound value. We evaluated that the proposed
method works well by conducting a simulation on a 1,000-user scale.
We confirm that the traffic volume could be controlled at a lower level
than the upper bound for all evaluated conditions. Moreover, our
method could control the traffic volume at 98.95% link usage against
the target value.