Abstract: Torrefaction of biomass pellets is considered as a
useful pretreatment technology in order to convert them into a high
quality solid biofuel that is more suitable for pyrolysis, gasification,
combustion, and co-firing applications. In the course of torrefaction,
the temperature varies across the pellet, and therefore chemical
reactions proceed unevenly within the pellet. However, the
uniformity of the thermal distribution along the pellet is generally
assumed. The torrefaction process of a single cylindrical pellet is
modeled here, accounting for heat transfer coupled with chemical
kinetics. The drying sub-model was also introduced. The nonstationary
process of wood pellet decomposition is described by the
system of non-linear partial differential equations over the
temperature and mass. The model captures well the main features of
the experimental data.
Abstract: In the present study, a numerical approach to describe the pyrolysis of a single solid particle of wood is used to study the influence of various conditions such as particle size, heat transfer coefficient, reactor temperature and heating rate. The influence of these parameters in the change of the duration of the pyrolysis cycle was studied. Mathematical modeling was employed to simulate the heat, mass transfer, and kinetic processes inside the reactor. The evolutions of the mass loss as well as the evolution of temperature inside the thick piece are investigated numerically. The elaborated model was also employed to study the effect of the reactor temperature and the rate of heating on the change of the temperature and the local loss of the mass inside the piece of wood. The obtained results are in good agreement with the experimental data available in the literature.
Abstract: Electro-osmosis in clayey soils and sediments, for
purposes of clay consolidation, dewatering, or cleanup, and electro
injection in porous media is widespread recent decades. It is
experimentally found that the chemical properties of porous media
especially PH change the characteristics of media. Electro-osmotic
conductivity is a function of soil and grout material chemistry,
altering with time. Many numerical approaches exist to simulate the
of electro kinetic flow rate considering chemical changes. This paper
presents a simplified analytical solution for constant flow rate based
on varying electro osmotic conductivity and time dependent viscosity
for injection of colloidal silica.
Abstract: In this work, by replacing the traditional solid spokes with colloidal spokes, a vehicle wheel with a built-in suspension structure is proposed. Following the background and description of the wheel system, firstly, a vibration model of the wheel equipped with colloidal spokes is proposed, and based on such model the equivalent damping coefficients and spring constants are identified. Then, a modified model of a quarter-vehicle moving on a rough pavement is proposed in order to estimate the transmissibility of vibration from the road roughness to vehicle body. In the end, the optimal design of the colloidal spokes and the optimum number of colloidal spokes are decided in order to minimize the transmissibility of vibration, i.e., to maximize the ride comfort of the vehicle.
Abstract: In the last decades, psychological tests have been
gaining in popularity as a method used for evaluating personnel, and
they bring consulting companies solid profits rising by up to 10%
each year. The market is offering a growing range of tools for the
assessment of personality. Tests are used in organizations mainly in
the recruitment and selection of staff. This paper is an attempt to
initially diagnose the state of the use of psychological tests in Polish
companies on the basis of empirical research.
Abstract: Bottom ash from Municipal Solid Waste Incineration
(MSWI) can be viewed as a typical granular material because these
industrial by-products result from the incineration of various
domestic wastes. MSWI bottom ash is mainly used in road
engineering in substitution of the traditional natural aggregates. As
the characterization of their mechanical behavior is essential in order
to use them, specific studies have been led over the past few years. In
the first part of this paper, the mechanical behavior of MSWI bottom
ash is studied with triaxial tests. After, analysis of the experiment
results, the simulation of triaxial tests is carried out by using the
software package CESAR-LCPC. As the first approach in modeling
of this new class material, the Mohr-Coulomb model was chosen to
describe the evolution of material under the influence of external
mechanical actions.
Abstract: In India, most of the pavement is laid by bituminous
road and the consumption of binder is high for pavement construction
and also modified binders are used to satisfy any specific pavement
requirement. Since the binders are visco-elastic material which is
having the mechanical properties of binder transition from viscoelastic
solid to visco-elastic fluid. In this paper, two different
protocols were used to measure the viscosity property of binder using
a Brookfield Viscometer and there is a need to find the appropriate
mixing and compaction temperatures of various types of binders
which can result in complete aggregate coating and adequate field
density of HMA mixtures. The aim of this work is to find the
transition temperature from Non-Newtonian behavior to Newtonian
behavior of the binder by adopting a steady shear protocol and the
shear rate ramp protocol. The transition from non-Newtonian to
Newtonian can occur through an increase of temperature and shear of
the material. The test has been conducted for unmodified binder VG
30. The transition temperature was found in the unmodified binder
VG is 120oC. Therefore, the application of both modified binder and
unmodified binder in the pavement construction needs to be studied
properly by considering temperature and traffic loading factors of the
respective project site.
Abstract: Mineral product, waste concrete (fine aggregates),
waste in the optical field, industry, and construction employ separators
to separate solids and classify them according to their size. Various
sorting machines are used in the industrial field such as those operating
under electrical properties, centrifugal force, wind power, vibration,
and magnetic force. Study on separators has been carried out to
contribute to the environmental industry. In this study, we perform
CFD analysis for understanding the basic mechanism of the separation
of waste concrete (fine aggregate) particles from air with a machine
built with a rotor with blades. In CFD, we first performed
two-dimensional particle tracking for various particle sizes for the
model with 1 degree, 1.5 degree, and 2 degree angle between each
blade to verify the boundary conditions and the method of rotating
domain method to be used in 3D. Then we developed 3D numerical
model with ANSYS CFX to calculate the air flow and track the
particles. We judged the capability of particle separation for given size
by counting the number of particles escaping from the domain toward
the exit among 10 particles issued at the inlet. We confirm that
particles experience stagnant behavior near the exit of the rotating
blades where the centrifugal force acting on the particles is in balance
with the air drag force. It was also found that the minimum particle
size that can be separated by the machine with the rotor is determined
by its capability to stay at the outlet of the rotor channels.
Abstract: The major environmental risk of soil pollution is the
contamination of groundwater by infiltration of organic and inorganic
pollutants which can cause a serious menace. To prevent this risk and
to protect the groundwater, we proceeded in this study to test the
reliability of a biosolid as barrier to prevent the migration of very
dangerous pollutants as ‘Cadmium’ through the different soil layers. In this study, we tried to highlight the effect of several parameters
such as: turbidity (different cycle of Hydration/Dehydration),
rainfall, effect of initial Cd(II) concentration and the type of soil.
These parameters allow us to find the most effective manner to
integrate this barrier in the soil. From the results obtained, we found a
significant effect of the barrier. Indeed, the recorded passing
quantities are lowest for the highest rainfall; we noted also that the
barrier has a better affinity towards higher concentrations; the most
retained amounts of cadmium has been in the top layer of the two
types of soil tested, while the lowest amounts of cadmium are
recorded in the bottom layers of soils.
Abstract: River Hindon is an important river catering the
demand of highly populated rural and industrial cluster of western
Uttar Pradesh, India. Water quality of river Hindon is deteriorating at
an alarming rate due to various industrial, municipal and agricultural
activities. The present study aimed at identifying the pollution
sources and quantifying the degree to which these sources are
responsible for the deteriorating water quality of the river. Various
water quality parameters, like pH, temperature, electrical
conductivity, total dissolved solids, total hardness, calcium, chloride,
nitrate, sulphate, biological oxygen demand, chemical oxygen
demand, and total alkalinity were assessed. Water quality data
obtained from eight study sites for one year has been subjected to the
two multivariate techniques, namely, principal component analysis
and cluster analysis. Principal component analysis was applied with
the aim to find out spatial variability and to identify the sources
responsible for the water quality of the river. Three Varifactors were
obtained after varimax rotation of initial principal components using
principal component analysis. Cluster analysis was carried out to
classify sampling stations of certain similarity, which grouped eight
different sites into two clusters. The study reveals that the
anthropogenic influence (municipal, industrial, waste water and
agricultural runoff) was the major source of river water pollution.
Thus, this study illustrates the utility of multivariate statistical
techniques for analysis and elucidation of multifaceted data sets,
recognition of pollution sources/factors and understanding
temporal/spatial variations in water quality for effective river water
quality management.
Abstract: Sewage sludge is a biomass resource that can create a
solid fuel and electricity. Utilizing sewage sludge as a renewable
energy can contribute to the reduction of greenhouse gases. In Japan,
the "National Plan for the Promotion of Biomass Utilization" and the
“Priority Plan for Social Infrastructure Development" were approved
at cabinet meetings in December 2010 and August 2012, respectively,
to promote the energy utilization of sewage sludge. This study
investigated costs and greenhouse gas emission in different sewage
sludge treatments with technologies for energy from sewage sludge.
Expenses were estimated based on capital costs and O&M costs
including energy consumption of solid fuel plants and biogas power
generation plants for sewage sludge. Results showed that the cost of
sludge digestion treatment with solid fuel technologies was 8% lower
than landfill disposal. The greenhouse gas emission of sludge
digestion treatment with solid fuel technologies was also 6,390t as
CO2 smaller than landfill disposal. Biogas power generation reduced
the electricity of a wastewater treatment plant by 30% and the cost by
5%.
Abstract: This paper focuses on the mathematical modeling for
solidification of Al alloy in a cube mold cavity to study the
solidification behavior of casting process. The parametric
investigation of solidification process inside the cavity was
performed by using computational solidification/melting model
coupled with Volume of fluid (VOF) model. The implicit filling
algorithm is used in this study to understand the overall process from
the filling stage to solidification in a model metal casting process.
The model is validated with past studied at same conditions. The
solidification process is analyzed by including the effect of pouring
velocity as well as natural convection from the wall and geometry of
the cavity. These studies show the possibility of various defects
during solidification process.
Abstract: This paper aimed to introduce the solution of concrete
slump recovery using chemical admixture type-F (superplasticizer,
naphthalene base) to the practice in order to solve unusable concrete
problem due to concrete loss its slump, especially for those tropical
countries that have faster slump loss rate. In the other hand, randomly
adding superplasticizer into concrete can cause concrete to segregate.
Therefore, this paper also develops the estimation model used to
calculate amount of second dose of superplasticizer need for concrete
slump recovery. Fresh properties of ordinary Portland cement
concrete with volumetric ratio of paste to void between aggregate
(paste content) of 1.1-1.3 with water-cement ratio zone of 0.30 to
0.67 and initial superplasticizer (naphthalene base) of 0.25%-1.6%
were tested for initial slump and slump loss for every 30 minutes for
one and half hour by slump cone test. Those concretes with slump
loss range from 10% to 90% were re-dosed and successfully
recovered back to its initial slump. Slump after re-dosed was tested
by slump cone test. From the result, it has been concluded that, slump
loss was slower for those mix with high initial dose of
superplasticizer due to addition of superplasticizer will disturb
cement hydration. The required second dose of superplasticizer was
affected by two major parameters, which were water-cement ratio
and paste content, where lower water-cement ratio and paste content
cause an increase in require second dose of superplasticizer. The
amount of second dose of superplasticizer is higher as the solid
content within the system is increase, solid can be either from cement
particles or aggregate. The data was analyzed to form an equation use
to estimate the amount of second dosage requirement of
superplasticizer to recovery slump to its original.
Abstract: Large quantities of solid wastes being generated
worldwide from sources such as household, domestic, industrial,
commercial and construction demolition activities, leads to
environmental concerns. Utilization of these wastes in making
building construction materials can reduce the magnitude of the
associated problems. When these waste products are used in place of
other conventional materials, natural resources and energy are
preserved and expensive and/or potentially harmful waste disposal is
avoided. Recycling which is regarded as the third most preferred waste
disposal option, with its numerous environmental benefits, stand as a
viable option to offset the environmental impact associated with the
construction industry. This paper reviews the results of laboratory tests and important
research findings, and the potential of using these wastes in building
construction materials with focus on sustainable development.
Research gaps, which includes; the need to develop standard mix
design for solid waste based building materials; the need to develop
energy efficient method of processing solid waste use in concrete; the
need to study the actual behavior or performance of such building
materials in practical application and the limited real life application
of such building materials have also been identified. A research is being proposed to develop an environmentally
friendly, lightweight building block from recycled waste paper,
without the use of cement, and with properties suitable for use as
walling unit. This proposed research intends to incorporate,
laboratory experimentation and modeling to address the identified
research gaps.
Abstract: The transesterification of dimethyl malonate (DMM)
with phenol has been studied in vapour phase over cordierite
honeycomb coated with solid acid catalysts such as ZrO2,
Mo(VI)/ZrO2 and SO42-/ZrO2. The catalytic materials were prepared
honeycomb coated, powder forms, and characterized for their total
surface acidity by NH3-TPD and crystalinity by powder XRD
methods. Phenyl methyl malonate (PMM) and diphenyl malonate
(DPM) were obtained as the reaction products. A good conversion of
DMM (up to 82%) of MPM with 95% selectivity was observed when
the reactions were carried out at a catalyst bed temperature of 200 °C
and flow-rate of 10 mL/h in presence of Mo(VI)/ZrO2 as catalyst.
However, over SO4^2-/ZrO2 catalyst, the yield of DPM was found to be
higher. The results have been interpreted based on the variation of
acidic properties and powder XRD phases of zirconia on
incorporation of Mo(VI) or SO42– ions. Transesterification reactions
were also carried out over powder forms of the catalytic materials
and the yield of the desired phenyl ester products were compared
with that of the HC coated catalytic materials. The solid acids were
found to be reusable when used for at least 5 reaction cycles.
Abstract: In the Solid-State-Drive (SSD) performance, whether
the data has been well parallelized is an important factor. SSD
parallelization is affected by allocation scheme and it is directly
connected to SSD performance. There are dynamic allocation and
static allocation in representative allocation schemes. Dynamic
allocation is more adaptive in exploiting write operation parallelism,
while static allocation is better in read operation parallelism.
Therefore, it is hard to select the appropriate allocation scheme when
the workload is mixed read and write operations. We simulated
conditions on a few mixed data patterns and analyzed the results to
help the right choice for better performance. As the results, if data
arrival interval is long enough prior operations to be finished and
continuous read intensive data environment static allocation is more
suitable. Dynamic allocation performs the best on write performance
and random data patterns.
Abstract: Background: Breast milk may impact early brain
development, with potentially important biological, medical and
social implications. There is an important discussion on which is the
adequate breastfeeding extension to the development consolidation
and how the children breastfeeding affects their psychomotor
development, in the first year of life, and in following periods as
well. Some special fats (LC PUFA) contained in breast milk play a
key role in the brain’s maturation and cognitive development or
social skills. These capacities created during breastfeeding time
would be unfolded throughout all lifespan. Aim of the study: In our research, we have studied the effect of
breastfeeding in preschooler's psychomotor assessment.
Method: This study was conducted in a sample of 158 preschool
children in Vlorë, Albania. We have measured the psychometric
parameters of preschoolers with ASQ-3 (Age&Stage Questionnaires-
3). The studied sample was divided in three groups according to their
breastfeeding duration (3, 6 and 12 months). Results: Children breastfed for only 3 months have definitely
lower psychometric scores compared to the ones with 6 or more
months of breastfeeding (respectively 217 to 239 ASQ-3 scores). Six
and twelvemonth breastfed children have progressively more odds to
have high levels of psychomotor development comparing to those
with only 3 months of breastfeeding. The most affected psychometric
domains by shortness of breastfeeding are Communication and
Global motor. Conclusion: This leads to conclusion that to ensure high
psychomotor parameters during childhood is necessary breastfeeding
for at least 6 months.
Abstract: Anaerobic digestion is a well-known technique for
sustainable energy recovery from sewage sludge. However, sewage
sludge digestion is restricted due to certain factors. Pre-treatment
methods have been established in various publications as a promising
technique to improve the digestibility of the sewage sludge and to
enhance the biogas generated which can be used for energy recovery.
In this study, continuous flow microwave (MW) pre-treatment with
different intensities were compared by using 5 L semi-continuous
digesters at a hydraulic retention time of 27 days. We focused on the
effects of MW at different intensities on the sludge solubilization,
sludge digestibility, and biogas production of the untreated and MW
pre-treated sludge. The MW pre-treatment demonstrated an increase
in the ratio of soluble chemical oxygen demand to total chemical
oxygen demand (sCOD/tCOD) and volatile fatty acid (VFA)
concentration. Besides that, the total volatile solid (TVS) removal
efficiency and tCOD removal efficiency also increased during the
digestion of the MW pre-treated sewage sludge compared to the
untreated sewage sludge. Furthermore, the biogas yield also
subsequently increases due to the pre-treatment effect. A higher MW
power level and irradiation time generally enhanced the biogas
generation which has potential for sustainable energy recovery from
sewage treatment plant. However, the net energy balance tabulation
shows that the MW pre-treatment leads to negative net energy production.
Abstract: In this study, static and dynamic responses of a typical
reinforced concrete solid slab, designed to British Standard (BS 8110:
1997) and under self and live loadings for dance halls are reported.
Linear perturbation analysis using finite element method was
employed for modal, impulse loading and frequency response
analyses of the slab under the aforementioned loading condition.
Results from the static and dynamic analyses, comprising of the slab
fundamental frequencies and mode shapes, dynamic amplification
factor, maximum deflection, stress distributions among other
valuable outcomes are presented and discussed. These were gauged
with the limiting provisions in the design code with a view of
justifying valid optimization objective function for the structure that
can ensure both adequate strength and economical section for large
clear span slabs. This is necessary owing to the continued increase in
cost of erecting building structures and the squeeze on public finance
globally.
Abstract: The wider growing Finite Element Method (FEM)
application is caused by its benefits of cost saving and environment
friendly. Also, by using FEM a deep understanding of certain
phenomenon can be achieved. This paper observed the role of
material properties and volumetric change when Solid State Phase
Transformation (SSPT) takes place in residual stress formation due to
a welding process of ferritic steels through coupled Thermo-
Metallurgy-Mechanical (TMM) analysis. The correctness of FEM residual stress prediction was validated by
experiment. From parametric study of the FEM model, it can be
concluded that the material properties change tend to over-predicts
residual stress in the weld center whilst volumetric change tend to
underestimates it. The best final result is the compromise of both by
incorporates them in the model which has a better result compared to
a model without SSPT.