Abstract: Two-dimensional Direct Numerical Simulation (DNS)
of high Schmidt number mass transfer in a convective flow environment
(Rayleigh-B'enard) is carried out and results are compared to
experimental data. A fourth-order accurate WENO-scheme has been
used for scalar transport in order to aim for a high accuracy in areas
of high concentration gradients. It was found that the typical spatial
distance between downward plumes of cold high concentration water
and the eddy size are in good agreement with experiments using a
combined PIV-LIF technique for simultaneous and spatially synoptic
measurements of 2D velocity and concentration fields.
Abstract: This paper addresses issues of integral steering of
vehicles with two steering axles, where the rear wheels are pivoted in
the direction of the front wheels, but also in the opposite direction.
The steering box of the rear axle is presented with simple linkages
(single contour) that correlate the pivoting of the rear wheels
according to the direction of the front wheels, respectively to the
rotation angle of the steering wheel. The functionality of the system
is analyzed – the extent to which the requirements of the integral
steering are met by the considered/proposed mechanisms. The paper
highlights the quality of the single contour linkages, with two driving
elements for meeting these requirements, emphasizing diagrams of
mechanisms with 2 driving elements. Cam variants are analyzed and
proposed for the rear axle steering box. Cam profiles are determined
by various factors.
Abstract: The study of the transport coefficients in electronic
devices is currently carried out by analytical and empirical models.
This study requires several simplifying assumptions, generally
necessary to lead to analytical expressions in order to study the
different characteristics of the electronic silicon-based devices.
Further progress in the development, design and optimization of
Silicon-based devices necessarily requires new theory and modeling
tools. In our study, we use the PSO (Particle Swarm Optimization)
technique as a computational tool to develop analytical approaches in
order to study the transport phenomenon of the electron in crystalline
silicon as function of temperature and doping concentration. Good
agreement between our results and measured data has been found.
The optimized analytical models can also be incorporated into the
circuits simulators to study Si-based devices without impact on the
computational time and data storage.
Abstract: In Algeria, liberalization reforms undertaken since the 1990s have resulted in negative effects on the development and management of irrigation schemes, as well as on the conditions of farmers. Reforms have been undertaken to improve the performance of irrigation schemes, such as the national plan of agricultural development (PNDA) in 2000 and the water pricing policy of 2005. However, after implementation of these policies, questions have arisen with regard to irrigation performance and its suitability for agricultural development. Hence, the aim of this paper is to provide insight into the profitability of irrigation during the transition period under current irrigation agricultural policies in Algeria. By using the method of farm crop budget analysis in the East Mitidja irrigation scheme, the returns from using surface water resources based on farm typology were found to vary among crops and farmers- groups within the scheme. Irrigation under the current situation is profitable for all farmers, including both those who benefit from subsidies and those who do not. However, the returns to water were found to be very sensitive to crop price fluctuations, particularly for non-subsidized groups and less so for those whose farming is based on orchards. Moreover, the socio-economic environment of the farmers contributed to less significant impacts of the PNDA policy. In fact, the limiting factor is not only the water, but also the lack of land ownership title. Market access constraints led to less agricultural investment and therefore to low intensification and low water productivity. It is financially feasible to recover the annual O&M costs in the irrigation scheme. By comparing the irrigation water price, returns to water, and O&M costs of water delivery, it is clear that irrigation can be profitable in the future. However, water productivity must be improved by enhancing farmers- income through farming investment, improving assets access, and the allocation of activities and crops which bring high returns to water; this could allow the farmers to pay more for water and allow cost recovery for water systems.
Abstract: The Wavelet-Galerkin finite element method for
solving the one-dimensional heat equation is presented in this work.
Two types of basis functions which are the Lagrange and multi-level
wavelet bases are employed to derive the full form of matrix system.
We consider both linear and quadratic bases in the Galerkin method.
Time derivative is approximated by polynomial time basis that
provides easily extend the order of approximation in time space. Our
numerical results show that the rate of convergences for the linear
Lagrange and the linear wavelet bases are the same and in order 2
while the rate of convergences for the quadratic Lagrange and the
quadratic wavelet bases are approximately in order 4. It also reveals
that the wavelet basis provides an easy treatment to improve
numerical resolutions that can be done by increasing just its desired
levels in the multilevel construction process.
Abstract: Experimental data from an atmospheric air/water terrain slugging case has been made available by the Shell Amsterdam research center, and has been subject to numerical simulation and comparison with a one-dimensional two-phase slug tracking simulator under development at the Norwegian University of Science and Technology. The code is based on tracking of liquid slugs in pipelines by use of a Lagrangian grid formulation implemented in Cµ by use of object oriented techniques. An existing hybrid spatial discretization scheme is tested, in which the stratified regions are modelled by the two-fluid model. The slug regions are treated incompressible, thus requiring a single momentum balance over the whole slug. Upon comparison with the experimental data, the period of the simulated severe slugging cycle is observed to be sensitive to slug generation in the horizontal parts of the system. Two different slug initiation methods have been tested with the slug tracking code, and grid dependency has been investigated.
Abstract: A numerical method is developed for simulating
the motion of particles with arbitrary shapes in an effectively
infinite or bounded viscous flow. The particle translational and
angular motions are numerically investigated using a fluid-structure
interaction (FSI) method based on the Arbitrary-Lagrangian-Eulerian
(ALE) approach and the dynamic mesh method (smoothing and
remeshing) in FLUENT ( ANSYS Inc., USA). Also, the effects of
arbitrary shapes on the dynamics are studied using the FSI method
which could be applied to the motions and deformations of a single
blood cell and multiple blood cells, and the primary thrombogenesis
caused by platelet aggregation. It is expected that, combined with a
sophisticated large-scale computational technique, the simulation
method will be useful for understanding the overall properties of blood
flow from blood cellular level (microscopic) to the resulting
rheological properties of blood as a mass (macroscopic).
Abstract: Small tanks, the ancient man-made rain water storage
systems, support the pheasant life and agriculture of the dry zone of
Sri Lanka. Many small tanks were abandoned with time due to
various reasons. Such tanks, rehabilitated in the recent past, were
found to be less sustainable and most of these rehabilitation
approaches have failed. The objective of this research is to assess the
impact of the rehabilitation approaches in the management of small
tanks in the Kurunegala District of Sri Lanka with respect to eight
small tanks. A Sustainability index was developed using seven
indicators representing the ability and commitment of the villagers to
maintain these tanks. The sustainability index of the eight tanks
varied between 79.2 and 47.2 out of a total score of 100. The
conclusion is that, the approaches used for tank rehabilitation have a
significant effect on the sustainability of the management of these
small tanks.
Abstract: The operation performance of a valveless micro-pump
is strongly dependent on the shape of connected nozzle/diffuser and
Reynolds number. The aims of present work are to compare the
performance curves of micropump with the original straight
nozzle/diffuser and contoured nozzle/diffuser under different back
pressure conditions. The tested valveless micropumps are assembled
of five pieces of patterned PMMA plates with hot-embracing
technique. The structures of central chamber, the inlet/outlet
reservoirs and the connected nozzle/diffuser are fabricated with laser
cutting machine. The micropump is actuated with circular-type PZT
film embraced on the bottom of central chamber. The deformation of
PZT membrane with various input voltages is measured with a
displacement laser probe. A simple testing facility is also constructed
to evaluate the performance curves for comparison.
In order to observe the evaluation of low Reynolds number
multiple vortex flow patterns within the micropump during suction
and pumping modes, the unsteady, incompressible laminar
three-dimensional Reynolds-averaged Navier-Stokes equations are
solved. The working fluid is DI water with constant thermo-physical
properties. The oscillating behavior of PZT film is modeled with the
moving boundary wall in way of UDF program. With the dynamic
mesh method, the instants pressure and velocity fields are obtained
and discussed.Results indicated that the volume flow rate is not
monotony increased with the oscillating frequency of PZT film,
regardless of the shapes of nozzle/diffuser. The present micropump
can generate the maximum volume flow rate of 13.53 ml/min when
the operation frequency is 64Hz and the input voltage is 140 volts.
The micropump with contoured nozzle/diffuser can provide 7ml/min
flow rate even when the back pressure is up to 400 mm-H2O. CFD
results revealed that the flow central chamber was occupied with
multiple pairs of counter-rotating vortices during suction and
pumping modes. The net volume flow rate over a complete
oscillating periodic of PZT
Abstract: We have measured the pressure drop and convective
heat transfer coefficient of water – based AL(25nm),AL2O3(30nm)
and CuO(50nm) Nanofluids flowing through a uniform heated
circular tube in the fully developed laminar flow regime. The
experimental results show that the data for Nanofluids friction factor
show a good agreement with analytical prediction from the Darcy's
equation for single-phase flow. After reducing the experimental
results to the form of Reynolds, Rayleigh and Nusselt numbers. The
results show the local Nusselt number and temperature have
distribution with the non-dimensional axial distance from the tube
entry. Study decided that thenNanofluid as Newtonian fluids through
the design of the linear relationship between shear stress and the rate
of stress has been the study of three chains of the Nanofluid with
different concentrations and where the AL, AL2O3 and CuO – water
ranging from (0.25 - 2.5 vol %). In addition to measuring the four
properties of the Nanofluid in practice so as to ensure the validity of
equations of properties developed by the researchers in this area and
these properties is viscosity, specific heat, and density and found that
the difference does not exceed 3.5% for the experimental equations
between them and the practical. The study also demonstrated that the
amount of the increase in heat transfer coefficient for three types of
Nano fluid is AL, AL2O3, and CuO – Water and these ratios are
respectively (45%, 32%, 25%) with insulation and without insulation
(36%, 23%, 19%), and the statement of any of the cases the best
increase in heat transfer has been proven that using insulation is
better than not using it. I have been using three types of Nano
particles and one metallic Nanoparticle and two oxide Nanoparticle
and a statement, whichever gives the best increase in heat transfer.
Abstract: Grid composite structures have many applications in aerospace industry in which deal with transverse loadings abundantly. In present paper a stiffened composite cylindrical shell with clamped-free boundary condition under transverse end load experimentally and numerically was studied. Some electrical strain gauges were employed to measure the strains. Also a finite element analysis was done for validation of experimental result. The FEM software used was ANSYS11. In addition, the results between stiffened composite shell and unstiffened composite shell were compared. It was observed that intersection of two stiffeners has an important effect in decrease of stress in the shell. Fairly good agreements were observed between the numerical and the measured results. According to recent studies about grid composite structures, it should be noted that any investigation like this research has not been reported.
Abstract: This work considered the thermodynamic feasibility
of scrubbing volatile organic compounds into biodiesel in view of
designing a gas treatment process with this absorbent. A detailed
vapour – liquid equilibrium investigation was performed using the
original UNIFAC group contribution method. The four biodiesels
studied in this work are methyl oleate, methyl palmitate, methyl
linolenate and ethyl stearate. The original UNIFAC procedure was
used to estimate the infinite dilution activity coefficients of 13
selected volatile organic compounds in the biodiesels. The
calculations were done at the VOC mole fraction of 9.213x10-8. Ethyl
stearate gave the most favourable phase equilibrium. A close
agreement was found between the infinite dilution activity coefficient
of toluene found in this work and those reported in literature.
Thermodynamic models can efficiently be used to calculate vast
amount of phase equilibrium behaviour using limited number of
experimental data.
Abstract: A ten-year grazing study was conducted at the
Agriculture and Agri-Food Canada Brandon Research Centre in
Manitoba to study the effect of alfalfa inclusion and fertilizer (N, P,
K, and S) addition on economics and efficiency of non-renewable
energy use in meadow brome grass-based pasture systems for beef
production. Fertilizing grass-only or alfalfa-grass pastures to full soil
test recommendations improved pasture productivity, but did not
improve profitability compared to unfertilized pastures. Fertilizing
grass-only pastures resulted in the highest net loss of any pasture
management strategy in this study. Adding alfalfa at the time of
seeding, with no added fertilizer, was economically the best pasture
improvement strategy in this study. Because of moisture limitations,
adding commercial fertilizer to full soil test recommendations is
probably not economically justifiable in most years, especially with
the rising cost of fertilizer. Improving grass-only pastures by adding
fertilizer and/or alfalfa required additional non-renewable energy
inputs; however, the additional energy required for unfertilized
alfalfa-grass pastures was minimal compared to the fertilized
pastures. Of the four pasture management strategies, adding alfalfa
to grass pastures without adding fertilizer had the highest efficiency
of energy use. Based on energy use and economic performance, the
unfertilized alfalfa-grass pasture was the most efficient and
sustainable pasture system.
Abstract: In this paper, we proposed a method for detecting consistency violation between UML state machine diagrams and communication diagrams using Alloy. Using input language of Alloy, the proposed method expresses system behaviors described by state machine diagrams, message sequences described by communication diagrams, and a consistency property. As a result of application for an example system, we confirmed that consistency violation could be detected using Alloy correctly.
Abstract: The research object was wheat bread. Experiments
were carried out at the Faculty of Food Technology of the Latvia
University of Agriculture. An active packaging in combination with
modified atmosphere (MAP, CO2 60% and N2 40%) was examined
and compared with traditional packaging in air ambiance. Polymer
Multibarrier 60, PP and OPP bags were used. Influence of iron based
oxygen absorber in sachets of 100 cc obtained from Mitsubishi Gas
Chemical Europe Ageless® was tested on the quality during the shelf
of wheat bread. Samples of 40±4 g were packaged in polymer
pouches (110 mm x 120 mm), hermetically sealed by MULTIVAC
C300 vacuum chamber machine, and stored in room temperature
+21.0±0.5 °C. The physiochemical properties – weight losses,
moisture content, hardness, pH, colour, changes of atmosphere
content (CO2 and O2) in headspace of packs, and microbial
conditions were analysed before packaging and in the 7th, 14th, 21st
and 28th days of storage.
Abstract: Transient shape variation of a rotating liquid dropletis
simulated numerically. The three dimensional Navier-Stokes
equations were solved by using the level set method. The shape
variation from the sphere to the rotating ellipsoid, and to the two-robed
shapeare simulated, and the elongation of the two-robed droplet is
discussed. The two-robed shape after the initial transient is found to be
stable and the elongation is almost the same for the cases with different
initial rotation rate. The relationship between the elongation and the
rotation rate is obtained by averaging the transient shape variation. It is
shown that the elongation of two-robed shape is in good agreement
with the existing experimental data. It is found that the transient
numerical simulation is necessary for analyzing the largely elongated
two-robed shape of rotating droplet.
Abstract: The characteristics of fluid flow and phase separation
in an oil-water separator were numerically analysed as part of the
work presented herein. Simulations were performed for different
velocities and droplet diameters, and the way this parameters can
influence the separator geometry was studied.
The simulations were carried out using the software package
Fluent 6.2, which is designed for numerical simulation of fluid flow
and mass transfer. The model consisted of a cylindrical horizontal
separator. A tetrahedral mesh was employed in the computational
domain. The condition of two-phase flow was simulated with the
two-fluid model, taking into consideration turbulence effects using
the k-ε model.
The results showed that there is a strong dependency of phase
separation on mixture velocity and droplet diameter. An increase in
mixture velocity will bring about a slow down in phase separation
and as a consequence will require a weir of greater height. An
increase in droplet diameter will produce a better phase separation.
The simulations are in agreement with results reported in literature
and show that CFD can be a useful tool in studying a horizontal oilwater
separator.
Abstract: “Garbage enzyme", a fermentation product of kitchen waste, water and brown sugar, is claimed in the media as a multipurpose solution for household and agricultural uses. This study assesses the effects of dilutions (5% to 75%) of garbage enzyme in reducing pollutants in domestic wastewater. The pH of the garbage enzyme was found to be 3.5, BOD concentration about 150 mg/L. Test results showed that the garbage enzyme raised the wastewater-s BOD in proportion to its dilution due to its high organic content. For mixtures with more than 10% garbage enzyme, its pH remained acidic after the 5-day digestion period. However, it seems that ammonia nitrogen and phosphorus could be removed by the addition of the garbage enzyme. The most economic solution for removal of ammonia nitrogen and phosphorus was found to be 9%. Further tests are required to understand the removal mechanisms of the ammonia nitrogen and phosphorus.
Abstract: The research objective of the project and article “The impact of Structural Funds on the growth of competitiveness of Polish agriculture" is to assess competitiveness of regions in Poland from the perspective of Polish agriculture by analysing the efficiency of the use of Structural Funds, the economic procedure of their distribution and the regulatory and organisational framework under the Rural Development Programme (RDP). It must be stressed that defining the scope of research in the above manner limits the analysis only to the part of Structural Funds directed to support Polish agriculture.
Abstract: The traditional Failure Mode and Effects Analysis
(FMEA) uses Risk Priority Number (RPN) to evaluate the risk level
of a component or process. The RPN index is determined by
calculating the product of severity, occurrence and detection indexes.
The most critically debated disadvantage of this approach is that
various sets of these three indexes may produce an identical value of
RPN. This research paper seeks to address the drawbacks in
traditional FMEA and to propose a new approach to overcome these
shortcomings. The Risk Priority Code (RPC) is used to prioritize
failure modes, when two or more failure modes have the same RPN.
A new method is proposed to prioritize failure modes, when there is a
disagreement in ranking scale for severity, occurrence and detection.
An Analysis of Variance (ANOVA) is used to compare means of
RPN values. SPSS (Statistical Package for the Social Sciences)
statistical analysis package is used to analyze the data. The results
presented are based on two case studies. It is found that the proposed
new methodology/approach resolves the limitations of traditional
FMEA approach.