Abstract: Reflux condensation occurs in vertical channels and tubes when there is an upward core flow of vapour (or gas-vapour mixture) and a downward flow of the liquid film. The understanding of this condensation configuration is crucial in the design of reflux condensers, distillation columns, and in loss-of-coolant safety analyses in nuclear power plant steam generators. The unique feature of this flow is the upward flow of the vapour-gas mixture (or pure vapour) that retards the liquid flow via shear at the liquid-mixture interface. The present model solves the full, elliptic governing equations in both the film and the gas-vapour core flow. The computational mesh is non-orthogonal and adapts dynamically the phase interface, thus produces a sharp and accurate interface. Shear forces and heat and mass transfer at the interface are accounted for fundamentally. This modeling is a big step ahead of current capabilities by removing the limitations of previous reflux condensation models which inherently cannot account for the detailed local balances of shear, mass, and heat transfer at the interface. Discretisation has been done based on finite volume method and co-located variable storage scheme. An in-house computer code was developed to implement the numerical solution scheme. Detailed results are presented for laminar reflux condensation from steam-air mixtures flowing in vertical parallel plate channels. The results include velocity and gas mass fraction profiles, as well as axial variations of film thickness.
Abstract: In this paper, the effects of fiber types and elevated
temperatures on compressive strength, modulus of rapture and the
bond characteristics of fiber reinforced concretes (FRC) are
presented. By using the three different types of fibers (steel fiber-SF,
polypropylene-PPF and polyvinyl alcohol-PVA), FRC specimens
were produced and exposed to elevated temperatures up to 800 ºC for
1.5 hours. In addition, a plain concrete (without fiber) was produced
and used as a control. Test results obtained showed that the steel fiber
reinforced concrete (SFRC) had the highest compressive strength,
modulus of rapture and bond stress values at room temperatures, the
residual bond, flexural and compressive strengths of both FRC and
plain concrete dropped sharply after exposure to high temperatures.
The results also indicated that the reduction of bond, flexural and
compressive strengths with increasing the exposed temperature was
relatively less for SFRC than for plain, and FRC with PPF and PVA.
Abstract: Increasing prevalence of childhood obesity has
increased the interest in early and late indicators of gaining weight.
Cell blood counts may be indicators of pro-inflammatory states. The
aim was to evaluate associations of hematological parameters,
including hematocrit (HTC), hemoglobin, blood cell counts and their
indices with the degree of obesity in pediatric population. A total of
249; -139 morbidly obese (MO), 82 healthy normal weight (NW) and
28 overweight (OW) children were included into the scope of the
study. WHO BMI-for age percentiles were used to form age- and sexmatched
groups. Informed consent forms and the Ethics Committee
approval were obtained. Anthropometric measurements were
performed. Hematological parameters were determined. Statistical
analyses were performed using SPSS. The degree for statistical
significance was p≤0.05. Significant differences (p=0.000) between
waist-to-hip ratios and head-to- neck ratios (hnrs) of MO and NW
children were detected. A significant difference between hnrs of OW
and MO children (p=0.000) was observed. Red cell distribution width
(RDW) was higher in OW children than NW group (p=0.030). Such
finding couldn’t be detected between MO and NW groups. Increased
RDW was prominent in OW children. The decrease in mean
corpuscular hemoglobin concentration (MCHC) values in MO
children was sharper than the values in OW children (p=0.006 vs
p=0.042) compared to those in NW group. Statistically higher HTC
levels were observed between MO-NW (p=0.014), but none between
OW-NW. Though the cause-effect relationship between obesity and
erythrocyte indices still needs further investigation, alterations in
RDW, HTC, MCHC during obesity may be of significance in the
early life.
Abstract: The development of allometric models is crucial to
accurate forest biomass/carbon stock assessment. The aim of this
study was to develop a set of biomass prediction models that will
enable the determination of total tree aboveground biomass for
savannah woodland area in Niger State, Nigeria. Based on the data
collected through biometric measurements of 1816 trees and
destructive sampling of 36 trees, five species specific and one site
specific models were developed. The sample size was distributed
equally between the five most dominant species in the study site
(Vitellaria paradoxa, Irvingia gabonensis, Parkia biglobosa,
Anogeissus leiocarpus, Pterocarpus erinaceous). Firstly, the
equations were developed for five individual species. Secondly these
five species were mixed and were used to develop an allometric
equation of mixed species. Overall, there was a strong positive
relationship between total tree biomass and the stem diameter. The
coefficient of determination (R2 values) ranging from 0.93 to 0.99 P
< 0.001 were realised for the models; with considerable low standard
error of the estimates (SEE) which confirms that the total tree above
ground biomass has a significant relationship with the dbh. F-test
values for the biomass prediction models were also significant at p
Abstract: A nanocrystalline thin film of ZnSe was successfully
electrodeposited on copper substrate using a non-aqueous solution
and subsequently annealed in air at 400°C. XRD analysis indicates
the polycrystalline deposit of (111) plane in both the cases. The
sharpness of the peak increases due to annealing of the film and
average grain size increases to 20 nm to 27nm. SEM photograph
indicate that grains are uniform and densely distributed over the
surface. Annealing increases the average grain size by 20%. The EDS
spectroscopy shows the ratio of Zn & Se is 1.1 in case of annealed
film. AFM analysis indicates the average roughness of the film
reduces from 181nm to 165nm due to annealing of the film. The
bandgap also decreases from 2.71eV to 2.62eV.
Abstract: The work studied the effect of germination on
proximate, phenol and flavonoid content and antioxidant activities
(AOA) of African Yam been (AYB). Germination was done in
controlled dark chamber (100% RH, 28oC). The proximate, phenol
and flavonoid content and antioxidant activities before and after
germination were investigated. The crude protein, moisture, and
crude fiber content of germinated AYB were significantly higher
(P
Abstract: Collection of storm water runoff and forcing it into the
groundwater is the need of the hour to sustain the ground water table.
However, the runoff entraps various types of sediments and other
floating objects whose removal are essential to avoid pollution of
ground water and blocking of pores of aquifer. However, it requires
regular cleaning and maintenance due to problem of clogging. To
evaluate the performance of filter system consisting of coarse sand
(CS), gravel (G) and pebble (P) layers, a laboratory experiment was
conducted in a rectangular column. The effect of variable thickness
of CS, G and P layers of the filtration unit of the recharge shaft on the
recharge rate and the sediment concentration of effluent water were
evaluated.
Medium sand (MS) of three particle sizes, viz. 0.150–0.300 mm
(T1), 0.300–0.425 mm (T2) and 0.425–0.600 mm of thickness 25 cm,
30 cm and 35 cm respectively in the top layer of the filter system and
having seven influent sediment concentrations of 250–3,000 mg/l
were used for experimental study. The performance was evaluated in
terms of recharge rates and clogging time. The results indicated that
100 % suspended solids were entrapped in the upper 10 cm layer of
MS, the recharge rates declined sharply for influent concentrations of
more than 1,000 mg/l. All treatments with higher thickness of MS
media indicated recharge rate slightly more than that of all treatment
with lower thickness of MS media respectively. The performance of
storm water infiltration systems was highly dependent on the
formation of a clogging layer at the filter. An empirical relationship
has been derived between recharge rates, inflow sediment load, size
of MS and thickness of MS with using MLR.
Abstract: This study was conducted to investigate the effect of
the antioxidant activity of germinated African Yam Bean (AYB) on
oxidative stress markers in alloxan induced diabetic rat. Rats were
randomized into three groups; control, diabetic and germinated AYB
– treated diabetic rats. The Total phenol and flavonoid content and
DPPH radical scavenging activity before and after germination were
investigated. The glucose level, lipid peroxidation and reduced
glutathione of the animals were also determined using standard
technique for four weeks. Germination increased the total phenol,
flavonoid and antioxidant activity of AYB extract by 19.14%,
32.28% and 57.25% respectively. The diabetic rats placed on
germinated AYB diet had a significant decrease in the blood glucose
and lipid peroxidation with a corresponding increase in glutathione
(p
Abstract: Karst term is the determiner of a variety of areas or
landforms and unique perspectives that have been formed in result of
the of the ingredients dissolution of rocks constituter by natural
waters. Shiraz area with an area of 5322km2 is located in the simple
folded belt in the southern part of Zagros Mountain of Fars, and is
surrounded with Limestone Mountains (Asmari formation). Shiraz
area is located in Calcareous areas. The infrastructure of this city is
lime and absorbing wells that the city can influence the Limestone
dissolution and those accelerate its rate and increase the cavitation
below the surface. Dasht-e Arjan is a graben, which has been created
as the result of activity of two normal faults in its east and west sides.
It is a complete sample of Karst plains (Polje) which has been created
with the help of tectonic forces (fault) and dissolution process of
water in Asmari limestone formation. It is located 60km. off south
west of Shiraz (on Kazeroon-Shiraz road). In 1971, UNESCO has
recognized this plain as a reserve of biosphere. It is considered as one
of the world’s most beautiful geological phenomena, so that most of
the world’s geologists are interested in visiting this place. The
purpose of this paper is to identify and introduce landscapes of Karst
features shiraz city and Dasht-e Arjan including Karst dissolution
features (Lapiez, Karst springs, dolines, caves, underground caves,
ponors, and Karst valleys), anticlines and synclines, and Arjan Lake.
Abstract: A feeding experiment was conducted to determine the
optimum dietary protein and lipid levels for juvenile fancy carp. Eight
experimental diets were formulated to contain four protein levels (200,
300, 400 and 500 g kg-1) with two lipid levels (70 and 140 g kg-1).
Triplicate groups of fish (initial weight, 12.1±0.2 g fish-1) were
hand-fed the diets to apparent satiation for 8 weeks. Fish growth
performance, feed utilization and feed intake were significantly
(P0.05). Weight gain and feed efficiency ratio tended to
increase as dietary protein level increased up to 400 and 500 g kg-1,
respectively. Daily feed intake of fish decreased with increasing
dietary protein level and that of fish fed diet contained 500 g kg-1
protein was significantly lower than other fish groups. The protein
efficiency ratio of fish fed 400 and 500 g kg-1 protein was lower than
that of fish fed 200 and 300 g kg-1 protein. Moisture, crude protein and
crude lipid contents of muscle and liver were significantly affected by
dietary protein, but not by dietary lipid level (P>0.05). The increase in
dietary lipid level resulted in an increase in linoleic acid in liver and
muscle paralleled with a decrease in n-3 highly unsaturated fatty acids
content in muscle of fish. In considering these results, it was concluded
that the diet containing 400 g kg-1 protein with 70 g kg-1 lipid level is
optimal for growth and efficient feed utilization of juvenile fancy carp.
Abstract: Oases are complex and fragile agro-ecosystems. They
have always existed in environments characterized by an arid climate,
scarcity of rainfall, high temperatures and high evaporation. These
palms have grown up despite the severity of the physical
characteristics thanks to the water's existence and irrigation practice.
The oases are generally spread along non-perennial rivers (wadis),
shallow water table or deep artesian groundwater. However, the
sustainability of oasis system is threatened by water scarcity and
declining of water table levels particularly in arid areas. Located in
the southern east area of Morocco, Tafilalet plain encompasses one of
the largest palm groves in the kingdom. In recent years, this area has
become increasingly threatened by water shortage and has seen a
sharp deterioration under the effect of several combined
anthropogenic and climatic factors. The Bayoud disease, successive
years of drought, Hassan Addakhil dam construction etc are all
factors that have affected both water and phoenicicole heritage of the
area. The objective of this study is to understand the interaction
between qualitative and quantitative degradation of groundwater
resources, and the palm grove dynamics, while reviewing the
assumption that groundwater resources contribute in a direct way to
the conservation of this oasis agroecosystem. A historical analysis
tracing both the oasis dynamics and the groundwater evolution has
been established. Data were collected from satellite images, surveys
with different actors (farmers, Regional Office for Agricultural
Development, Basin agency...). They were complemented by a
synthesis of numerous technical reports in the area. The results
showed that within 40 years, the thickness of the groundwater table
has dropped in 50 %. Along with this, there has been a downsizing of
date palm by 50 %. Areas with higher groundwater level were the
least affected by the downsizing. So we can say that the shallow
groundwater contribute significantly and directly to the water supply
of date palm through its root system, and largely ensures the oasis
ecosystem sustainability.
Abstract: Energy consumption and users’ satisfaction were
compared in three LEED certified office buildings in turkey and an
office building in Egypt. The field studies were conducted in summer
2012. The measured environmental parameters in the four buildings
were indoor air temperature, relative humidity, CO2 percentage and
light intensity. The traditional building is located in Smart Village in
Abu Rawash, Cairo, Egypt. The building was studied for 7 days
resulting in 84 responds. The three rated buildings are in Istanbul;
Turkey. A Platinum LEED certified office building is owned by
BASF and gained a platinum certificate for new construction and
major renovation. The building was studied for 3 days resulting in 13
responds. A Gold LEED certified office building is owned by BASF
and gained a gold certificate for new construction and major
renovation. The building was studied for 2 days resulting in 10
responds. A silver LEED certified office building is owned by
Unilever and gained a silver certificate for commercial interiors. The
building was studied for 7 days resulting in 84 responds.
The results showed that all buildings had no significant difference
regarding occupants’ satisfaction with the amount of lighting, noise
level, odor and access to the outdoor view. There was significant
difference between occupants’ satisfaction in LEED certified
buildings and the traditional building regarding the thermal
environment and the perception of the general environment (colors,
carpet and decoration. The findings suggest that careful design could
lead to a certified building that enhances the thermal environment and
the perception of the indoor environment leading to energy
consumption without scarifying occupants’ satisfaction.
Abstract: The crude oil in an oil well exists in various phases
such as gas, seawater, and sand, as well as oil. Therefore, a phase
separator is needed at the front of a single-phase pump for
pressurization and transfer. On the other hand, the application of a
multiphase pump can provide such advantages as simplification of the
equipment structure and cost savings, because there is no need for a
phase separation process. Therefore, the crude oil transfer method
using a multiphase pump is being applied to recently developed oil
wells. Due to this increase in demand, technical demands for the
development of multiphase pumps are sharply increasing, but the
progress of research into related technologies is insufficient, due to the
nature of multiphase pumps that require high levels of skills. This
study was conducted to verify the reliability of pump performance
evaluation using numerical analysis, which is the basis of the
development of a multiphase pump. For this study, a model was
designed by selecting the specifications of this study. The performance
of the designed model was evaluated through numerical analysis and
experiment. The results of the performance evaluation were compared
to verify the reliability of the result using numerical analysis.
Abstract: The manufacturing technology of band cotton is very
delicate and depends to choice of certain parameters such as torsion
of warp yarn.
The fabric elasticity is achieved without the use of any elastic
material, chemical expansion, artificial or synthetic and it’s capable
of creating pressures useful for therapeutic treatments.
Before use, the band is subjected to treatments of specific
preparation for obtaining certain elasticity, however, during its
treatment, there are some regression parameters. The dependence of
manufacturing parameters on the quality of the chemical treatment
was confirmed.
The aim of this work is to improve the properties of the fabric
through the development of manufacturing technology appropriately.
Finally for the treatment of the strip pancake 100% cotton, a
treatment method is recommended.
Abstract: In this study, first thermoplastic composite materials
/plates that have high ballistic impact resistance were produced. For
this purpose, the thermoplastic prepreg and the vacuum bagging
technique were used to produce a composite material. Thermoplastic
prepregs (resin-impregnated fiber) that are supplied ready to be used,
namely high-density polyethylene (HDPE) was chosen as matrix and
unidirectional glass fiber was used as reinforcement. In order to
compare the fiber configuration effect on mechanical properties,
unidirectional and biaxial prepregs were used. Then the
microstructural properties of the composites were investigated with
scanning electron microscopy (SEM) analysis. Impact properties of
the composites were examined by Charpy impact test and tensile
mechanical tests and then the effects of ultraviolet irradiation were
investigated on mechanical performance.
Abstract: Three dimensional non-Interlaced carbon fibre
reinforced silicon carbide (3-D-Cf/SiC) composites with pyrocarbon
interphase were fabricated using isothermal chemical vapor
infiltration (ICVI) combined with polymer impregnation pyrolysis
(PIP) process. Polysilazane (PSZ) is used as a preceramic polymer to
obtain silicon carbide matrix. Thermo gravimetric analysis (TGA),
Infrared spectroscopic analysis (IR) and X-ray diffraction (XRD)
analysis were carried out on PSZ pyrolysed at different temperatures
to understand the pyrolysis and obtaining the optimum pyrolysing
condition to yield β-SiC phase. The density of the composites was
1.94 g cm-3 after the 3-D carbon preform was SiC infiltrated for 280 h
with one intermediate polysilazane pre-ceramic PIP process.
Mechanical properties of the composite materials were investigated
under tensile, flexural, shear and impact loading. The values of
tensile strength were 200 MPa at room temperature (RT) and 195
MPa at 500°C in air. The average RT flexural strength was 243 MPa.
The lower flexural strength of these composites is because of the
porosity. The fracture toughness obtained from single edge notched
beam (SENB) technique was 39 MPa.m1/2. The work of fracture
obtained from the load-displacement curve of SENB test was 22.8
kJ.m-2. The composites exhibited excellent impact resistance and the
dynamic fracture toughness of 44.8 kJ.m-2 is achieved as determined
from instrumented Charpy impact test. The shear strength of the
composite was 93 MPa, which is significantly higher compared 2-D
Cf/SiC composites. Microstructure evaluation of fracture surfaces
revealed the signatures of fracture processes and showed good
support for the higher toughness obtained.
Abstract: The present environmental issues have made aircraft jet noise reduction a crucial problem in aero-acoustics research. Acoustic studies reveal that addition of chevrons to the nozzle reduces the sound pressure level reasonably with acceptable reduction in performance. In this paper comprehensive numerical studies on acoustic characteristics of different types of chevron nozzles have been carried out with non-reacting flows for the shape optimization of chevrons in supersonic nozzles for aerospace applications. The numerical studies have been carried out using a validated steady 3D density based, k-ε turbulence model. In this paper chevron with sharp edge, flat edge, round edge and U-type edge are selected for the jet acoustic characterization of supersonic nozzles. We observed that compared to the base model a case with round-shaped chevron nozzle could reduce 4.13% acoustic level with 0.6% thrust loss. We concluded that the prudent selection of the chevron shape will enable an appreciable reduction of the aircraft jet noise without compromising its overall performance. It is evident from the present numerical simulations that k-ε model can predict reasonably well the acoustic level of chevron supersonic nozzles for its shape optimization.
Abstract: This paper conducts a comparison study using KES-FB and PhabrOmeter to measure 58 selected warp knitted fabric hand properties. Fabric samples were selected and measured by both KES-FB and PhabrOmeter. Results show differences between these two measurement methods. Smoothness and stiffness values obtained by KES-FB were found significant correlated (p value = 0.003 and 0.022) to the PhabrOmeter results while softness values between two measurement methods did not show significant correlation (p value = 0.828). Disagreements among these two measurement methods imply limitations on different mechanism principles when facing warp knitted fabrics. Subjective measurement methods and further studies are suggested in order to ascertain deeper investigation on the mechanisms of fabric hand perceptions.
Abstract: This study compared the mechanical and microstructural properties produced during friction stir welding (FSW) of S275 structural steel in air and underwater. Post weld tests assessed the tensile strength, micro-hardness, distortion, Charpy impact toughness and fatigue performance in each case. The study showed that there was no significant difference in the strength, hardness or fatigue life of the air and underwater specimens. However, Charpy impact toughness was shown to decrease for the underwater specimens and was attributed to a lower degree of recrystallization caused by the higher rate of heat loss experienced when welding underwater. Reduced angular and longitudinal distortion was observed in the underwater welded plate compared to the plate welded in air.
Abstract: This paper investigates the effect of simultaneous placement of DGs and smart meters (SMs), on voltage profile improvement in active distribution networks (ADNs). A substantial center of attention has recently been on responsive loads initiated in power system problem studies such as distributed generations (DGs). Existence of responsive loads in active distribution networks (ADNs) would have undeniable effect on sizing and siting of DGs. For this reason, an optimal framework is proposed for sizing and siting of DGs and SMs in ADNs. SMs are taken into consideration for the sake of successful implementing of demand response programs (DRPs) such as direct load control (DLC) with end-side consumers. Looking for voltage profile improvement, the optimization procedure is solved by genetic algorithm (GA) and tested on IEEE 33-bus distribution test system. Different scenarios with variations in the number of DG units, individual or simultaneous placing of DGs and SMs, and adaptive power factor (APF) mode for DGs to support reactive power have been established. The obtained results confirm the significant effect of DRPs and APF mode in determining the optimal size and site of DGs to be connected in ADN resulting to the improvement of voltage profile as well.