Abstract: In this work, the precipitation of asphaltene from a Malaysian light oil reservoir was studies. A series of experiments were designed and carried out to examine the effect of CO2 injection on asphaltene precipitation. Different pressures of injections were used in Dynamic flooding experiment in order to investigate the effect of pressure versus injection pore volume of CO2. These dynamic displacement tests simulate reservoir condition. Results show that by increasing the pore volume of injected gas asphaltene precipitation will increases, also rise in injection pressure causes less precipitation. Sandstone core plug was used to represent reservoir formation during displacement test; therefore it made it possible to study the effect of present of asphaltene on formation. It is found out that the precipitated asphaltene can reduce permeability and porosity which is not favorable during oil production.
Abstract: This paper describes a one-dimensional numerical model for natural gas production from the dissociation of methane hydrate in hydrate-capped gas reservoir under depressurization and thermal stimulation. Some of the hydrate reservoirs discovered are overlying a free-gas layer, known as hydrate-capped gas reservoirs. These reservoirs are thought to be easiest and probably the first type of hydrate reservoirs to be produced. The mathematical equations that can be described this type of reservoir include mass balance, heat balance and kinetics of hydrate decomposition. These non-linear partial differential equations are solved using finite-difference fully implicit scheme. In the model, the effect of convection and conduction heat transfer, variation change of formation porosity, the effect of using different equations of state such as PR and ER and steam or hot water injection are considered. In addition distributions of pressure, temperature, saturation of gas, hydrate and water in the reservoir are evaluated. It is shown that the gas production rate is a sensitive function of well pressure.
Abstract: Some physical properties of musk lime (Citrus
microcarpa) were determined in this study. The average moisture
content (wet basis) of the fruit was found to be 85.10 (±0.72) %. The
mean of length, width and thickness of the fruit was 26.36 (±0.97),
26.40 (±1.04) and 25.26 (±0.94) mm respectively. The average value
for geometric mean diameter, sphericity, aspect ratio, mass, surface
area, volume, true density, bulk density and porosity was 26.00
(±0.82) mm, 98.67 (±2.04) %, 100.23 (±3.28) %, 10.007 (±0.878) g,
2125.07 (±133.93) mm2, 8800.00 (±731.82) mm3, 1002.87 (±39.16)
kgm-3, 501.70 (±22.58) kgm-3 and 49.89 (±3.15) % respectively.
The coefficient of static friction on four types of structural surface
was found to be varying from 0.238 (±0.025) for glass to 0.247
(±0.024) for steel surface.
Abstract: Industrial radiography is a famous technique for the identification and evaluation of discontinuities, or defects, such as cracks, porosity and foreign inclusions found in welded joints. Although this technique has been well developed, improving both the inspection process and operating time, it does suffer from several drawbacks. The poor quality of radiographic images is due to the physical nature of radiography as well as small size of the defects and their poor orientation relatively to the size and thickness of the evaluated parts. Digital image processing techniques allow the interpretation of the image to be automated, avoiding the presence of human operators making the inspection system more reliable, reproducible and faster. This paper describes our attempt to develop and implement digital image processing algorithms for the purpose of automatic defect detection in radiographic images. Because of the complex nature of the considered images, and in order that the detected defect region represents the most accurately possible the real defect, the choice of global and local preprocessing and segmentation methods must be appropriated.
Abstract: A steady two-dimensional magnetohydrodynamics
flow and heat transfer over a stretching vertical sheet influenced by
radiation and porosity is studied. The governing boundary layer
equations of partial differential equations are reduced to a system of
ordinary differential equations using similarity transformation. The
system is solved numerically by using a finite difference scheme
known as the Keller-box method for some values of parameters,
namely the radiation parameter N, magnetic parameter M, buoyancy
parameter l , Prandtl number Pr and permeability parameter K. The
effects of the parameters on the heat transfer characteristics are
analyzed and discussed. It is found that both the skin friction
coefficient and the local Nusselt number decrease as the magnetic
parameter M and permeability parameter K increase. Heat transfer
rate at the surface decreases as the radiation parameter increases.
Abstract: In this paper the combination of thermal oxidation and
electrochemical anodizing processes is used to produce titanium
oxide layers. The response of titanium alloy Ti6Al4V to oxidation
processes at various temperatures and electrochemical anodizing in
various voltages are investigated. Scanning electron microscopy
(SEM); X-Ray Diffraction (XRD) and porosity determination have
been used to characterize the oxide layer thickness, surface
morphology, oxide layer-substrate adhesion and porosity. In the first
experiment, samples modified by thermal oxidation process then
followed by electrochemical anodizing. Second experiment consists
of surfaces modified by electrochemical anodizing process and then
followed by thermal oxidation. The first method shows better
properties than other one. In second experiment, Surfaces modified
were achieved by thicker and more adherent thick oxide layers on
titanium surface. The existence of an electrochemical anodized oxide
layer did not improve the adhesion of thermal oxide layer. The high
temperature, thermal formation of an oxide layer leads to a coarse
oxide grain morphology and a complete oxidative particle. In
addition, in high temperature oxidation porosity content is increased.
The oxide layer of thermal oxidation and electrochemical anodizing
processes; on Ti–6Al–4V substrate was covered with different
colored oxide layers.
Abstract: The objective of this work was to examine the changes
in non destructive properties caused by carbonation of CEM II
mortar. Samples of CEM II mortar were prepared and subjected to
accelerated carbonation at 20°C, 65% relative humidity and 20% CO2
concentration. We examined the evolutions of the gas permeability,
the thermal conductivity, the thermal diffusivity, the volume of the
solid phase by helium pycnometry, the longitudinal and transverse
ultrasonic velocities. The principal contribution of this work is that,
apart of the gas permeability, changes in other non destructive
properties have never been studied during the carbonation of cement
materials. These properties are important in predicting/measuring the
durability of reinforced concrete in CO2 environment. The
carbonation depth and the porosity accessible to water were also
reported in order to explain comprehensively the changes in non
destructive parameters.
Abstract: spherical porous carbon particles with
controllable porosity with a mean size of 2.5m have been
prepared using a spray drying method with organic particle
colloidal template. As a precursor, a mixing solution of carbon
nanopowder and polystyrene (PS) particles as a template was
used. The result showed that the particles with a good porous
structure could be obtained. The pore size and shape (spherical)
were identical to the initial template, giving a potential way for
further developments. The control of particle porosity was also
possible and reported in this paper, in which this control could
be achieved by means of PS concentration.
Abstract: In this paper, numerical simulation is used to
investigate the thermal performance of liquid cooling heatsink with
microchannels due to geometric arrangement. Commercial software
ICEPAK is utilized for the analysis. The considered parameters
include aspect ratio, porosity and the length and height of
microchannel. The aspect ratio varies from 3 to 16 and the length of
microchannel is 10mm, 14mm, and 18mm. The height of
microchannel is 2mm, 3mm and 4mm. It is found short channel have
better thermal efficiency than long channel at 490Pa. No matter the
length of channel the best aspect ratio is 4. It is also noted that pressure
difference at 2940Pa the best aspect ratio from 4 to 8, it means pressure
difference affect aspect ratio, effective thermal resistance at low
pressure difference but lower effective thermal resistance at high
pressure difference.
Abstract: In this investigation, anatase TiO2 thin films were
grown by radio frequency magnetron sputtering on glass substrates at
a high sputtering pressure and room temperature. The anatase films
were then annealed at 300-600 °C in air for a period of 1 hour. To
examine the structure and morphology of the films, X-ray diffraction
(XRD) and atomic force microscopy (AFM) methods were used
respectively. From X-ray diffraction patterns of the TiO2 films, it was
found that the as-deposited film showed some differences compared
with the annealed films and the intensities of the peaks of the
crystalline phase increased with the increase of annealing
temperature. From AFM images, the distinct variations in the
morphology of the thin films were also observed. The optical
constants were characterized using the transmission spectra of the
films obtained by UV-VIS-IR spectrophotometer. Besides, optical
thickness of the film deposited at room temperature was calculated
and cross-checked by taking a cross-sectional image through SEM.
The optical band gaps were evaluated through Tauc model. It was
observed that TiO2 films produced at room temperatures exhibited
high visible transmittance and transmittance decreased slightly with
the increase of annealing temperatures. The films were found to be
crystalline having anatase phase. The refractive index of the films
was found from 2.31-2.35 in the visible range. The extinction
coefficient was nearly zero in the visible range and was found to
increase with annealing temperature. The allowed indirect optical
band gap of the films was estimated to be in the range from 3.39 to
3.42 eV which showed a small variation. The allowed direct band
gap was found to increase from 3.67 to 3.72 eV. The porosity was
also found to decrease at a higher annealing temperature making the
film compact and dense.
Abstract: Coal will continue to be the predominant source of
global energy for coming several decades. The huge generation of fly
ash (FA) from combustion of coal in thermal power plants (TPPs) is
apprehended to pose the concerns of its disposal and utilization. FA
application based on its typical characteristics as soil ameliorant for
agriculture and forestry is the potential area, and hence the global
attempt. The inferences drawn suffer from the variations of ash
characteristics, soil types, and agro-climatic conditions; thereby
correlating the effects of ash between various plant species and soil
types is difficult. Indian FAs have low bulk density, high water
holding capacity and porosity, rich silt-sized particles, alkaline
nature, negligible solubility, and reasonable plant nutrients. Findings
of the demonstrations trials for more than two decades from lab/pot
to field scale long-term experiments are developed as FA soil
amendment technology (FASAT) by Central Institute of Mining and
Fuel Research (CIMFR), Dhanbad. Performance of different crops
and plant species in cultivable and problematic soils, are
encouraging, eco-friendly, and being adopted by the farmers. FA
application includes ash alone and in combination with
inorganic/organic amendments; combination treatments including
bio-solids perform better than FA alone. Optimum dose being up to
100 t/ha for cultivable land and up to/ or above 200 t/ha of FA for
waste/degraded land/mine refuse, depending on the characteristics of
ash and soil. The elemental toxicity in Indian FA is usually not of
much concern owing to alkaline ashes, oxide forms of elements, and
elemental concentration within the threshold limits for soil
application. Combating toxicity, if any, is possible through
combination treatments with organic materials and phytoremediation.
Government initiatives through extension programme
involving farmers and ash generating organizations need to be
accelerated
Abstract: Rapid prototyping (RP) techniques are a group of
advanced manufacturing processes that can produce custom made
objects directly from computer data such as Computer Aided Design
(CAD), Computed Tomography (CT) and Magnetic Resonance
Imaging (MRI) data. Using RP fabrication techniques, constructs
with controllable and complex internal architecture with appropriate
mechanical properties can be achieved. One of the attractive and
promising utilization of RP techniques is related to tissue engineering
(TE) scaffold fabrication. Tissue engineering scaffold is a 3D
construction that acts as a template for tissue regeneration. Although
several conventional techniques such as solvent casting and gas
forming are utilized in scaffold fabrication; these processes show
poor interconnectivity and uncontrollable porosity of the produced
scaffolds. So, RP techniques become the best alternative fabrication
methods of TE scaffolds. This paper reviews the current state of the
art in the area of tissue engineering scaffolds fabrication using
advanced RP processes, as well as the current limitations and future
trends in scaffold fabrication RP techniques.
Abstract: The major part of light weight timber constructions
consists of insulation. Mineral wool is the most commonly used
insulation due to its cost efficiency and easy handling. The fiber
orientation and porosity of this insulation material enables flowthrough.
The air flow resistance is low. If leakage occurs in the
insulated bay section, the convective flow may cause energy losses
and infiltration of the exterior wall with moisture and particles. In
particular the infiltrated moisture may lead to thermal bridges and
growth of health endangering mould and mildew. In order to prevent
this problem, different numerical calculation models have been
developed. All models developed so far have a potential for
completion. The implementation of the flow-through properties of
mineral wool insulation may help to improve the existing models.
Assuming that the real pressure difference between interior and
exterior surface is larger than the prescribed pressure difference in the
standard test procedure for mineral wool ISO 9053 / EN 29053,
measurements were performed using the measurement setup for
research on convective moisture transfer “MSRCMT".
These measurements show, that structural inhomogeneities of
mineral wool effect the permeability only at higher pressure
differences, as applied in MSRCMT. Additional microscopic
investigations show, that the location of a leak within the
construction has a crucial influence on the air flow-through and the
infiltration rate. The results clearly indicate that the empirical values
for the acoustic resistance of mineral wool should not be used for the
calculation of convective transfer mechanisms.
Abstract: Microtomographic images and thin section (TS)
images were analyzed and compared against some parameters of
geological interest such as porosity and its distribution along the
samples. The results show that microtomography ( CT) analysis,
although limited by its resolution, have some interesting information
about the distribution of porosity (homogeneous or not) and can also
quantify the connected and non-connected pores, i.e., total porosity.
TS have no limitations concerning resolution, but are limited by the
experimental data available in regards to a few glass sheets for
analysis and also can give only information about the connected
pores, i.e., effective porosity. Those two methods have their own
virtues and flaws but when paired together they are able to
complement one another, making for a more reliable and complete
analysis.
Abstract: Experimental investigation of the effect of
hydrophobic injection on siloxane basis on the properties of oldfashioned
type of ceramic brick is presented in the paper. At the
experimental testing, the matrix density, total open porosity, pore size
distribution, sorptivity, water absorption coefficient, sorption and
desorption isotherms are measured for the original, as well as the
hydrophobic-injection treated brick. On the basis of measured data,
the functionality of the hydrophobic injection for the moisture ingress
prevention into the studied ceramic brick is assessed.
Abstract: In this work Membrane Distillation is applied to
concentrate orange Juice. Clarified orange juice (11o Brix) obtained
from fresh fruits and a sugar solution was subjected to membrane
distillation. The experiments were performed on a flat sheet module
using orange juice and sucrose solution as feeds. The concentration
of a sucrose solution, used as a model fruit juice and also orange
juice, was carried out in a direct contact membrane distillation using
hydrophobic PTFE membrane of pore size 0.2 μm and porosity 70%.
Surface modification of PTFE membrane has been carried out by
treating membrane with alcohol and water solution to make it
hydrophilic and then hydrophobicity was regained by drying. The
influences of the feed temperature, feed concentration, flow rate,
operating time on the permeate flux were studied for treated and non
treated membrane. In this work treated and non treated membrane
were compared in terms of water flux, Within the tested range, MD
with surface modified membrane the water flux has been
significantly improved by treating the membrane surface.
Abstract: High strength concrete has been used in situations
where it may be exposed to elevated temperatures. Numerous authors
have shown the significant contribution of polypropylene fiber to the
spalling resistance of high strength concrete.
When cement-based composite that reinforced by polypropylene
fibers heated up to 170 °C, polypropylene fibers readily melt and
volatilize, creating additional porosity and small channels in to the
matrix that cause the poor structure and low strength.
This investigation develops on the mechanical properties of mortar
incorporating polypropylene fibers exposed to high temperature.
Also effects of different pozzolans on strength behaviour of samples
at elevated temperature have been studied.
To reach this purpose, the specimens were produced by partial
replacement of cement with finely ground glass, silica fume and rice
husk ash as high reactive pozzolans. The amount of this replacement
was 10% by weight of cement to find the effects of pozzolans as a
partial replacement of cement on the mechanical properties of
mortars. In this way, lots of mixtures with 0%, 0.5%, 1% and 1.5% of
polypropylene fibers were cast and tested for compressive and
flexural strength, accordance to ASTM standard. After that
specimens being heated to temperatures of 300, 600 °C, respectively,
the mechanical properties of heated samples were tested.
Mechanical tests showed significant reduction in compressive
strength which could be due to polypropylene fiber melting. Also
pozzolans improve the mechanical properties of sampels.
Abstract: Horizontal continuous casting is widely used to
produce semi-finished non-Ferrous products. Homogeneity in the
metallurgical characteristics and mechanical properties for this
product is vital for industrial application. In the present work, the
microstructure and mechanical properties of a horizontal continuous
cast two-phase brass billet have been studied. Impact strength and
hardness variations were examined and the phase composition and
porosity studied with image analysis software. Distinct differences in
mechanical properties were observed between the upper, middle and
lower parts of the billet, which are explained in terms of the
morphology and size of the phase in the microstructure. Hardness
variation in the length of billet is higher in upper area but impact
strength is higher in lower areas.
Abstract: The flow and heat transfer characteristics for natural
convection along an inclined plate in a saturated porous medium with
an applied magnetic field have been studied. The fluid viscosity has
been assumed to be an inverse function of temperature. Assuming
temperature vary as a power function of distance. The transformed
ordinary differential equations have solved by numerical integration
using Runge-Kutta method. The velocity and temperature profile
components on the plate are computed and discussed in detail for
various values of the variable viscosity parameter, inclination angle,
magnetic field parameter, and real constant (λ). The results have also
been interpreted with the aid of tables and graphs. The numerical
values of Nusselt number have been calculated for the mentioned
parameters.
Abstract: Concrete performance is strongly affected by the
particle packing degree since it determines the distribution of the
cementitious component and the interaction of mineral particles. By
using packing theory designers will be able to select optimal
aggregate materials for preparing concrete with low cement content,
which is beneficial from the point of cost. Optimum particle packing
implies minimizing porosity and thereby reducing the amount of
cement paste needed to fill the voids between the aggregate particles,
taking also the rheology of the concrete into consideration. For
reaching good fluidity superplasticizers are required. The results from
pilot tests at Luleå University of Technology (LTU) show various
forms of the proposed theoretical models, and the empirical approach
taken in the study seems to provide a safer basis for developing new,
improved packing models.