Abstract: The quantified residence time distribution (RTD)
provides a numerical characterization of mixing in a reactor, thus
allowing the process engineer to better understand mixing
performance of the reactor.This paper discusses computational
studies to investigate flow patterns in a two impinging streams
cyclone reactor(TISCR) . Flow in the reactor was modeled with
computational fluid dynamics (CFD). Utilizing the Eulerian-
Lagrangian approach, implemented in FLUENT (V6.3.22), particle
trajectories were obtained by solving the particle force balance
equations. From simulation results obtained at different Δts, the mean
residence time (tm) and the mean square deviation (σ2) were
calculated. a good agreement can be observed between predicted and
experimental data. Simulation results indicate that the behavior of
complex reactor systems can be predicted using the CFD technique
with minimum data requirement for validation.
Abstract: In the present study, a numerical analysis is carried
out to investigate unsteady MHD (magneto-hydrodynamic) flow and
heat transfer of a non-Newtonian second grade viscoelastic fluid
over an oscillatory stretching sheet. The flow is induced due to an
infinite elastic sheet which is stretched oscillatory (back and forth) in
its own plane. Effect of viscous dissipation and joule heating are
taken into account. The non-linear differential equations governing
the problem are transformed into system of non-dimensional
differential equations using similarity transformations. A newly
developed meshfree numerical technique Element free Galerkin
method (EFGM) is employed to solve the coupled non linear
differential equations. The results illustrating the effect of various
parameters like viscoelastic parameter, Hartman number, relative
frequency amplitude of the oscillatory sheet to the stretching rate and
Eckert number on velocity and temperature field are reported in
terms of graphs and tables. The present model finds its application in
polymer extrusion, drawing of plastic films and wires, glass, fiber
and paper production etc.
Abstract: Steroidal hormones with the efficient changes on the epiphyseal growth plate may influence tissue structure properties. Presents paper to investigate the effects of gonadectomy in the pattern distribution of the epiphyseal structure. Fifteen adult female New Zealand white rabbits were separated into three groups. One group was intact and others groups were selected for surgical operation. From these two groups, one group carried out steroidal administration. The results obtained showed that there is no statistically difference in the mean diameter of the growth plate cells between all three groups. The maximum value of the cartilage cells were allocated to the gonadectomized group and the minimum number were observed in Hormonal induced group significantly. Growth plate height was significantly greater in gonadectomized group than in two other groups.
Abstract: The possibility of producing drinking water from
brackish ground water using Vacuum membrane distillation (VMD)
process was studied. It is a rising technology for seawater or brine
desalination process. The process simply consists of a flat sheet
hydrophobic micro porous PTFE membrane and diaphragm vacuum
pump without a condenser for the water recovery or trap. In this
work, VMD performance was investigated for aqueous NaCl solution
and natural ground water. The influence of operational parameters
such as feed flow rate (30 to 55 l/h), feed temperature (313 to 333 K),
feed salt concentration (5000 to 7000 mg/l) and permeate pressure
(1.5 to 6 kPa) on the membrane distillation (MD) permeation flux
have been investigated. The maximum flux reached to 28.34 kg/m2 h
at feed temperature, 333 K; vacuum pressure, 1.5 kPa; feed flow rate,
55 l/h and feed salt concentration, 7000 mg/l. The negligible effects
in the reduction of permeate flux found over 150 h experimental run
for salt water. But for the natural ground water application over 75 h,
scale deposits observed on the membrane surface and 29% reduction
in the permeate flux over 75 h. This reduction can be eliminated by
acidification of feed water. Hence, promote the research attention in
apply of VMD for the ground water purification over today-s
conventional RO operation.
Abstract: Silk sericin (SS) is a glue-like protein from silkworm
cocoon. With its outstanding moisturization and activation collagen
synthesis properties, silk protein is applied for wound healing. Since
wound dressing in film preparation can facilitate patients-
convenience and reduce risk of wound contraction, SS and polyvinyl
alcohol (PVA) films were prepared with various concentrations of
SS. Their physical properties such as surface density, light
transmission, protein dissolution and tensile modulus were
investigated. The results presented that 3% SS with 2% PVA is the
best ingredient for SS film forming.
Abstract: One of the potential and effective ways of
storing thermal energy in buildings is the integration of brick with phase change materials (PCMs). This paper presents a two-dimensional model for simulating and analyzing of PCM
in order to minimize energy consumption in the buildings. The numerical approach has been used with the real weather data of a selected city of Iran (Tehran). Two kinds of brick integrated PCM are investigated and compared base on
outdoor weather conditions and the amount of energy
consumption. The results show a significant reduction in
maximum entering heat flux to building about 32.8%
depending on PCM quantity. The results are analyzed by
various temperature contour plots. The contour plots
illustrated the time dependent mechanism of entering heat flux for a brick integrated with PCM. Further analysis is developed to investigate the effect of PCM location on the inlet heat flux. The results demonstrated that to achieve maximum performance of PCM it is better to locate PCM near the outdoor.
Abstract: Capital structure is one of the most important financial
decisions in corporate financing strategy. It involves the choice of
debt and equity level in financing a company-s operations. This study
aims to investigate whether the capital structure choice of Malaysian
electrical and electronic manufacturing companies that are listed in
the Bursa Malaysia can be explained by factors that have been found
by most studies as dominant determinants of capital structure
(company size, profitability, asset tangibility, liquidity and growth).
Using debt ratio as the proxy for capital structure and applying
pooled ordinary least square multiple regression estimation, the
results showed that on average, Malaysian electrical and electronic
manufacturing companies used less debt in funding their business
operations. The findings also showed that size and asset tangibility
has a significant positive relationship with debt level, while liquidity
has a negative significant relationship with leverage.
Abstract: Manufacturing, production and service industries within Libya have struggled with many problems during the past two decades due to many difficulties. These problems have created a negative impact on the productivity and utilization of many industries around the country. This paper studies the implementation levels of the manufacturing control systems known as Manufacturing Resource Planning (MRPII) being adapted within some Libyan industries. A survey methodology has been applied for this research, based on the survey analysis, the results pointed out that the system within these industries has a modest strategy towards most of the areas that are considered as being very crucial in implementing these systems successfully. The findings also show a variation within these implementation levels with a respect to the key-elements that related to MRPII, giving the highest levels in the emphasise on financial data accuracy. The paper has also identified limitations within the investigated manufacturing and managerial areas and has pointed to where senior managers should take immediate actions in order to achieve effective implementation of MRPII within their business area.
Abstract: A numerical investigation of the effects of nanosecond
barrier discharge on the stability of a two-dimensional free shear layer
is performed. The computations are carried out using a compressible
Navier-Stokes algorithm coupled with a thermodynamic model of the
discharge. The results show that significant increases in the shear
layer-s momentum thickness and Reynolds stresses occur due to
actuation. Dependence on both frequency and amplitude of actuation
are considered, and a comparison is made of the computed growth
rates with those predicted by linear stability theory. Amplitude and
frequency ranges for the efficient promotion of shear-layer instabilities
are identified.
Abstract: The use of un-activated bentonite, and un-activated
bentonite blended with limestone for the treatment of acid mine
drainage (AMD) was investigated. Batch experiments were
conducted in a 5 L PVC reactor. Un-activated bentonite on its own
did not effectively neutralize and remove heavy metals from AMD.
The final pH obtained was below 4 and the metal removal efficiency
was below 50% for all the metals when bentonite solid loadings of 1,
5 and 10% were used. With un-activated bentonite (1%) blended with
1% limestone, the final pH obtained was approximately 7 and metal
removal efficiencies were greater than 60% for most of the metals.
The Langmuir isotherm gave the best fit for the experimental data
giving correlation coefficient (R2) very close to 1. Thus, it was
concluded that un-activated bentonite blended with limestone is
suitable for potential applications in removing heavy metals and
neutralizing AMD.
Abstract: This study investigated the climatic factors associated
with Influenza incidence in Nakhon Si Thammarat, Southern
Thailand. Climatic factors comprised of the amount of rainfall,
percent of rainy days, relative humidity, wind speed, maximum,
minimum temperatures and temperature difference. A multiple
stepwise regression technique was used to fit the statistical model.
The result showed that the temperature difference and percent of
rainy days were positively associated with Influenza incidence in
Nakhon Si Thammarat.
Abstract: In the present paper, we investigate a differential subordination
involving multiplier transformation related to a sector in the
open unit disk E = {z : |z| < 1}. As special cases to our main
result, certain sufficient conditions for strongly starlike and strongly
convex functions are obtained.
Abstract: In this paper multi-objective genetic algorithms are
employed for Pareto approach optimization of ideal Turboshaft
engines. In the multi-objective optimization a number of conflicting
objective functions are to be optimized simultaneously. The
important objective functions that have been considered for
optimization are specific thrust (F/m& 0), specific fuel consumption
( P S ), output shaft power 0 (& /&) shaft W m and overall efficiency( ) O
η .
These objectives are usually conflicting with each other. The design
variables consist of thermodynamic parameters (compressor pressure
ratio, turbine temperature ratio and Mach number).
At the first stage single objective optimization has been
investigated and the method of NSGA-II has been used for multiobjective
optimization. Optimization procedures are performed for
two and four objective functions and the results are compared for
ideal Turboshaft engine. In order to investigate the optimal
thermodynamic behavior of two objectives, different set, each
including two objectives of output parameters, are considered
individually. For each set Pareto front are depicted. The sets of
selected decision variables based on this Pareto front, will cause the
best possible combination of corresponding objective functions.
There is no superiority for the points on the Pareto front figure,
but they are superior to any other point. In the case of four objective
optimization the results are given in tables.
Abstract: Today, Higher Education in a global scope is subordinated to the greater institutional controls through the policies of the Quality of Education. These include processes of over evaluation of all the academic activities: students- and professors- performance, educational logistics, managerial standards for the administration of institutions of higher education, as well as the establishment of the imaginaries of excellence and prestige as the foundations on which universities of the XXI century will focus their present and future goals and interests. But at the same time higher education systems worldwide are facing the most profound crisis of sense and meaning and attending enormous mutations in their identity. Based in a qualitative research approach, this paper shows the social configurations that the scholars at the Universities in Mexico build around the discourse of the Quality of Education, and how these policies put in risk the social recognition of these individuals.
Abstract: The influence of extrusion parameters on surface
quality and properties of AA6061+x% vol. SiC (x = 0; 2,5; 5; 7,5;10)
composites was discussed in this paper. The averages size of
AA6061 and SiC particles were 10.6 μm and 0.42 μm, respectively.
Two series of composites (I - compacts were preheated at extrusion
temperature through 0.5 h and cooled by water directly after process;
II - compacts were preheated through 3 hours and were not cooled)
were consolidated via powder metallurgy processing and extruded by
KoBo method. High values of density for both series of composites
were achieved. Better surface quality was observed for II series of
composites. Moreover, for these composites lower (compared to I
series) but more uniform strength properties over the cross-section of
the bar were noticed. Microstructure and Young-s modulus
investigations were made.
Abstract: This paper proposes the requirements and design of
RFID based system for SFC (Shop Floor Control) in order to achieve
the factory real time controllability, Allowing to develop EManufacturing
System. The detailed logical specifications of the core
functions and the design diagrams of RFID based system are
developed. Then RFID deployment in E-Manufacturing systems is
investigated..
Abstract: Optical Bursts Switching (OBS) is a relatively new
optical switching paradigm. Contention and burst loss in OBS
networks are major concerns. To resolve contentions, an interesting
alternative to discarding the entire data burst is to partially drop the
burst. Partial burst dropping is based on burst segmentation concept
that its implementation is constrained by some technical challenges,
besides the complexity added to the algorithms and protocols on both
edge and core nodes. In this paper, the burst segmentation concept is
investigated, and an implementation scheme is proposed and
evaluated. An appropriate dropping policy that effectively manages
the size of the segmented data bursts is presented. The dropping
policy is further supported by a new control packet format that
provides constant transmission overhead.
Abstract: This study has investigated a vehicle Lumped
Parameter Model (LPM) in frontal crash. There are several ways for
determining spring and damper characteristics and type of problem
shall be considered as system identification. This study use Genetic
Algorithm (GA) procedure, being an effective procedure in case of
optimization issues, for optimizing errors, between target data
(experimental data) and calculated results (being obtained by
analytical solving). In this study analyzed model in 5-DOF then
compared our results with 5-DOF serial model. Finally, the response
of model due to external excitement is investigated.
Abstract: Manganese steel (Hadfield) is one of the important
alloys in industry due to its special properties. High work hardening
ability with appropriate toughness and ductility are the properties that
caused this alloy to be used in wear resistance parts and in high
strength condition. Heat treatment is the main process through which
the desired mechanical properties and microstructures are obtained in
Hadfield steel. In this study various heat treatment cycles, differing in
austenising temperature, time and quenching solution are applied. For
this purpose, the same samples of manganese steel was heat treated in
9 different cycles, and then the mechanical properties and
microstructures were investigated. Based on the results of the study,
the optimum heat treatment cycle was obtained.
Abstract: It is essential to have a uniform and calm flow field
for a settling tank to have high performance. In general, the
recirculation zones always occurred in sedimentation tanks. The
presence of these regions may have different effects. The nonuniformity
of the velocity field, the short-circuiting at the surface and
the motion of the jet at the bed of the tank that occurs because of the
recirculation in the sedimentation layer, are affected by the geometry
of the tank. There are some ways to decrease the size of these dead
zones, which would increase the performance. One of the ways is to
use a suitable baffle configuration. In this study, the presence of
baffle with different position has been investigated by a finite volume
method, with VOF (Volume of Fluid) model. Besides, the k-ε
turbulence model is used in the numerical calculations. The results
indicate that the best position of the baffle is obtained when the
volume of the recirculation region is minimized or is divided to
smaller part and the flow field trend to be uniform in the settling
zone.