Title: |
Effect of water absorption, porosity and
sorptivity on durability of geopolymer mortars |
Author (s): |
Suresh Thokchom, Partha Ghosh and Somnath
Ghosh |
Abstract: |
An experimental program
was carried out to study the effect of water absorption, apparent
porosity and sorptivity on durability of fly ash based geopolymer mortar
specimens in Sulfuric acid solution. Low calcium Class F fly ash was
activated by a mixture of NaOH and Na2SiO3
containing 5% to 8% Na2O with water to fly ash ratio of 0.33.
The durability of geopolymer mortar specimens was evaluated on the basis
of reduction in compressive strength when exposed in 10% Sulfuric acid
solution for 24 weeks. Specimens containing lesser alkali were found to
possess higher apparent porosity, water absorption and water sorptivity.
After 24 weeks in sulfuric acid solution, specimens still had
substantial residual compressive strength ranging from 29.4% to 54.8%.
Specimens with higher water absorption, porosity and water sorptivity
lost more strength than those with lesser corresponding values. Results
obtained in the experimental program indicate that porosity, sorptivity
and water absorption of geopolymer mortar specimens influences the
durability of geopolymer mortars in sulfuric acid. |
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Title: |
Modeling break time on gravel pack fluid
at different breaker concentrations and temperatures |
Author (s): |
Joel O. F., Ademiluyi F. T. and Iyalla M.
C. |
Abstract: |
The effect of gel
breakers on 60lbs/Mgals gravel pack fluid at different temperatures and
concentrations was investigated. Tests at temperatures of 190oF, 210oF
and 230oF with high temperature (HT) breaker of concentrations 5.0gal/Mgal,
10gal/Mgal and 15gal/Mgal, respectively were also investigated. The
study revealed that break time is a function of temperature and
concentration, at a higher temperature and concentration, respectively,
gel break is faster and vice-versa. Model coefficients were obtained
using DATA FIT engineering software and results indicated that
Exponential model described best the variation of break time with
breaker concentration and temperature. Model which predicts break time
at any breaker concentration and Bottom Hole Temperature was developed.
A model equation was developed for different temperatures and
concentrations. Results calculated from the model equation showed a good
agreement with experimental values with less than 10% deviation. This
will help predict gel break time at different concentrations and
temperatures thereby saving time and rigor associated with actual
laboratory pilot test. |
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Title: |
A novel approach for contrast enhancement
based on histogram equalization followed by median filter |
Author (s): |
P. Jagatheeswari, S. Suresh Kumar and
M.Rajaram |
Abstract: |
The goal of image
enhancement technique is to improve a characteristic or quality of an
image, such that the resulting image is better than the original image.
Histogram equalization (HE) is widely used for contrast enhancement.
However, it tends to change the brightness of an image. Preserving the
input brightness of the image is required to avoid annoying artifacts in
the output image. To overcome this drawback Brightness preserving
Bi-histogram equalization (BBHE) has been proposed and analyzed
mathematically that it can preserve the original brightness to a certain
extends. However, there are still cases that are not handled well by
BBHE, as they require higher degree of preservation. The extension of
BBHE is Minimum Mean Brightness Error Bi-Histogram Equalization (MMBEBHE).
The result of MMBEBHE is bad for the image with a lot details. To
overcome these drawbacks, a new method is proposed. In this method,
image enhancement is performed by MMBEBHE based on a modified contrast
stretching manipulation. While the image is enhanced, the impulse
noises present in the images are also enhanced. To avoid this effect,
the enhanced image is passed through a median filter. The median filter
is an effective method for the removal of impulse based noise on images.
This is due to the partial averaging effect of the median filter and its
biasing of the input stream, rather than straight mathematical
averaging. |
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Title: |
Point load test application for estimating
compressive strength of concrete structures from small core |
Author (s): |
A. Zacoeb and K. Ishibashi |
Abstract: |
To estimate a
compressive strength from existing concrete structures by core drilling
are usually gathered with a diameter specimen of 100mm or three times of
maximum coarse aggregate size and examined by uniaxial compressive
strength (UCS) test as stated in JIS A1170. To get an alternative
solution with smaller specimen, point load test (PLT) has been selected
which is a simple test and widely accepted in rock materials research,
but relatively new in concrete. The reliability of PLT is examined by
extracting a lot of core drilled specimen from ready mixed concrete
blocks with maximum coarse aggregate size, Gmax of 20mm in
representative of architectural structures and 40mm in representative of
civil structures on the range of concrete grade from 16 to 50. The
reference of strength is resulted from concrete core diameter of 100 and
125mm with h/d ratio of 2.0, and examined by UCS test with compressive
strength of concrete core of f’cc in results. The core specimen
diameters are 35 and 50mm with h/d ratio of 1.5 and 2.0, and examined by
PLT with point load index of IS in results. The estimation of
compressive strength is conducted by making a linear approximation for
IS to f’cc for each group of Gmax and h/d. This study also evaluates the
reliability of test results for each core specimen and proposes a new
geometric correction factor. |
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Title: |
Studies on removal of toxic metals from
waste water using pseudomonas species |
Author (s): |
Korrapati Narasimhulu and Parcha
Sreenivasa Rao |
Abstract: |
Toxic trace metals can
be hazardous even at very low concentrations. When they get into water
supplies and aqueous environments the health of plants and animals, as
well as humans, can be impaired. Toxic trace metals are commonly found
in wastewater and removing them efficiently presents a unique challenge.
The discharge of heavy metals into aquatic ecosystems has become a
matter of concern in India over the last few decades. These pollutants
are introduced into the aquatic systems significantly as a result of
various industrial operations. Biosorption experiments for Chromium (Cr
(VI)), Copper (Cu (II)), Cadmium (Cd (II)) and Nickel (Ni (II)) were
investigated in this study using nonliving biomass of different
Pseudomonas species. The Langmuir and Freundlich models for the
different biosorbent were applied and tested. Maximum Cr (VI) removal
reached around 40% and its removal increased with the increase of Cr
(VI) influent. Cu (II) removal was at its maximum value in presence of
Cr (VI) as a binary metal, which reached 95% of its influent
concentration. Concerning to Cd (II) and Ni (II) similar removal ratios
were obtained, since it was ranged between 36 to 90% and their maximum
removal were obtained in the case of individual Cd (II) and Ni (II). |
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Title: |
Pre-rake diversity with generalized
orthogonal codes and imperfect channel conditions for FDD/DS-CDMA
systems |
Author (s): |
C. Subhas, K. Rama Naidu and Y.
Venkatarami Reddy |
Abstract: |
The Pre-Rake diversity
combining technique decreases the complexity, size and cost of the
mobile unit while achieving the same inter symbol interference (ISI)
mitigation effects of conventional Rake receiver for direct sequence
code division multiple access (DS-CDMA) systems. The technique is based
on preprocessing of signal at the transmitter relying on knowledge of
the channel state information. This a priori information is available in
time division duplex (TDD) mode due to channel reciprocity. In frequency
division duplex (FDD) mode the channel has to be estimated at mobile
unit (MU) for the downlink and fed to base station to predict the
channel for downlink time slot. In this paper, we compare the
performance of Pre-Rake system with different spreading codes. We will
also propose a method for channel prediction in FDD mode and evaluate
the system under ideal and predicted channel conditions using
generalized orthogonal (GO) and Walsh codes through analytical and
computer simulations for DS-CDMA downlink. |
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Title: |
Reichardt’s dye as sensor material
detected oxymethyl group in the cation part of imidazolium ionic liquid
structure |
Author (s): |
Krzysztof Pawlak, Andrzej Skrzypczak and
Grazyna Ewa Bialek-Bylka |
Abstract: |
A sensor that can
detect methoxy group in cation part of imidazolium ionic liquid was
developed based on Reichardt's solvatochromic dye. The Reichardt's dye
incorporated into three ionic liquids:
1-methyl-3-octyloxymethylimidazolium tetrafluoroborate,
1-methyl-3-hexyloxymethylimidazolium bis(trifluoromethylsulfonyl)imide,
and 1-methyl-3-octylimidazolium tetrafluoroborate (without oxymethyl
group in the structure), has been study by absorption and steady state
fluorescence spectra. The striking solvatochromic effect was observed in
ionic liquid includes oxymethyl group in the structure. |
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Title: |
A comparative analysis of aircraft noise
performances |
Author (s): |
Nicola Gualandi and Luca Mantecchini |
Abstract: |
This paper presents a
comparative analysis of aircraft acoustical performance based on the
definition of a noise performance indicator called ENSA (equivalent
number of standard aircraft). ENSA methodology is based on the choice of
a standard aircraft, then ENSA’s values are obtained by comparing the
generic aircraft’s performances with the standard aircraft’s
performances. The performance evaluation is performed by analysing for
each aircraft the equivalent number of standard aircrafts movements
generating a noise level corresponding with one standard aircraft
movement. This comparative analysis permits the evaluation of aircraft
noise performance by comparing the ENSA values for different aircrafts. |
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Title: |
Finite element modeling and simulation of
contact interaction and deformation of carbon fibrous composite beam
against rigid indenter |
Author (s): |
Umar Farooq and
Karl Gregory |
Abstract: |
This study is concerned
with finite element modelling and simulation of fibrous composite beams
contact with rigid indenter. Mathematical formulations consisting of
contact law and indentation wrapping have been developed. Fibrous
orientated modulii and types quasi-isotropic materials were also
presented. Finite element method software ABAQUS was chosen to perform
simulation incorporating dynamic contact in time-domain using implicit
dynamics routine. To improve convergence, mapped meshing techniques were
employed to mesh the regions of high stress gradient with fine meshes
and coarse meshes for the rest. Results from homogeneous beam were
compared with the results from quasi-isotropic beams with 8, 12, and 24
plies and found to be in good agreement. The present study has
demonstrated computationally model the contribution of fibre orientation
effects on resulting damage and response of composite beams while
interacting with rigid indenter. |
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