Anul XXII (2015), Nr. 1
COVER
TABLE OF
CONTENTS
ARTICLES
Performance Evaluation of an Egusimelon Washing Machine
Adebayo A.A.,
Yusuf K.A.
Traditionally, woven basket in the flowing water stream with heaps of
melon balls at the washing site is being employed in washing of Egusimelon
seeds in most local settings in Nigeria. This traditional melon
washing method was observed to be associated with high level of
drudgery ranging from the famers developing pains all over the body,
infection with waterborne diseases and low washing output. In this
study, Egusimelon washing machine was fabricated in the Department
of Agricultural and BioEnvironmental Engineering of Auchi Polytechnic,
Auchi, Nigeria.The machine after construction was evaluated using a
factorial experiment in a Randomized Complete Block Design (RCBD)
involving three levels of speed (1008, 1482 and 1901rpm), three levels
of feedrate (2.6, 3.3, and 3.9kg) and three levels of sieve size (6.0, 7.5
and 10.5) in three replications. The result obtained was statistically
analyzed using SPSS 19.0 software and Duncan’s New Multiple Range
Test (DNMRT) to determine the level of significant among the
treatment factors. However, the performance parameters considered
for measurement are Washing Efficiency and Washing Capacity.
Washing Efficiency and Washing Capacity of 80% and 1.16kg/min
respectively was obtainedat Speed of 1008 rpm, Feedrate of 2.6kg/min
and sieve size of 7.5mm. Also, the result of the statistical analysis
shows that the machine speed, federate, sieve size and the interactions
between them are all significant factors on the Washing Capacity and
Washing Efficiency of the machine at 5% confidence level.
Keywords: Egusimelon, feedrate, washing efficiency, washing capacity,
sieve size (EMWV)
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Contributions to Design of Actuators functioning
with Nitinol Active Springs
Daniel Amariei,
Ion Vela,
Cornel Mituletu,
Marius Tufoi
SThe paper presents the research results achieved in order to perform a
comparison regarding the influence of natural and forced cooling process
applied to the Nitinol active springs inside a linear motion actuator.
SMAs offer attractive potentials such as reversible strains of several
percent, generation of high recovery stresses and high power / weight
ratios. The actuator behavior was simulated first with SolidWorks and
experimentally tested for results validation.
Keywords: actuators, Nitinol, springs, simulation, stroke
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Optimizing Distribution Problems using WinQSB Software
Daniel Mihai Amariei,
Alexandru Victor Amariei
In the present paper we are presenting a problem of distribution using
the Network Modeling Module of the WinQSB software, were we have 5
athletes which we must assign the optimal sample, function of the obtained
time, so as to obtain the maximum output of the athletes. Also
we analyzed the case of an accident of 2 athletes, the coupling of 3
athletes with 5 various athletic events causing the maximum coupling,
done using the Hungarian algorithm.
Keywords: Hungarian algorithm, distribution, athletes, athletic events,
optimum solutions, optimal solution
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Special Cases Solution of the Transport Problem
OlgaIoana Amariei,
Nicoleta Gillich,
Codruta Oana Hamat
In the present paper we are presenting an optimal way to solve the
transport problems with intermediate centers, taking in consideration
several approaches, using the Network Modelling Module of the
WinQSB software. The transfer problem represents a special case of
the transport problem, an extension of it.
Keywords: the transportation problem, intermediate center, objective
function, optimal solution
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The Transport Problem utilized for Machines Optimal Allocation
OlgaIoana Amariei,
Codruta Oana Hamat,
Liviu Coman
The present paper presents an optimal allocation mode of the machines
in a manner to maximize the profit. Starting from provided data
– time standard, technical itineraries, production volume, working regime
and continuing with the determined ones – duration, necessary
number of machines, unit profit, the problem became a maximization
transport problem.
Keywords: transportation problem, time standard, optimal solution,
alternative solution, machining
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Comparative Study for Optimization of CNC Milling
MU Technological Processes
Alexandru Victor Amariei,
Liviu Coman
The present paper presents a study regarding technological optimization
of wooden eyeglasses frames manufacturing process on CNC machine
tools using 3 respectively 4 working axes. The general conclusion
which arises from this study is that 4 axes manufacturing process reduce
substantially the production necessary duration compared with 3
axes machining process.
Keywords: machinetool, CNC, CAD, CAM, CAE
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Damming Opportunities in Case of Natural Calamities
Silviu Razvan Avram,
Tiberiu Stefan Manescu
This paper deals with technical matters relating to the protection of
existing and innovative riverbanks, farmland and homes in case of
natural disasters. Also includes comparative presentation of proposed
solutions regarding the advantages and disadvantages occurring during
developments.
Keywords: disaster, opportunities, metal cofferdam, piling Polyvinyl
Chloride
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BOn the Numerical Modeling of Confined Masonry
Structures for Inplane Earthquake Loads
Mircea Barnaure,
Daniel Nicolae Stoica
The seismic design of confined masonry structures involves the use of
numerical models. As there are many parameters that influence the
structural behavior, these models can be very complex and unsuitable
for the current design purposes of practicing engineers. Simplified
models could lead to reasonably accurate results, but caution should be
given to the simplification assumptions. An analysis of various parameters
considered in the numerical modeling of confined masonry structural
walls is made. Conclusions regarding the influence of simplified
procedures on the results are drawn.
Keywords: confined masonry, numerical modeling, push over analysis
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Contributions in the Preparation and Processing of
Composite Material Type Silumin 3  Reinforced Matrix with S235JR Steel Mesh
Remus BeluNica,
ReluCostel Ciubotariu
In the paper are presented concrete data on developing technological
batches of metal composite material (MCM) type Silumin 3reinforced
matrix with steel mesh S235JR, with the indicating of the parameter
and of the distinct stages of work. The samples from prepared batches
were cut along and across by water jet abrasive process and were subjected
to a destructive testing program and microstructural examination,
obtaining results in concordance with the desired quality. The
abrasive material used for cut was GMA granite with the average mesh
of 80, the particle size ranging between 150300 µm, density 2300
kg/m3 and melting point 1240°C.
Keywords: composite materials, destructive testing program, microstructural
examinations
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Structural Considerations on Fatigue Cracks
Cornel Bit
This paper has been focused on the modern theoretical and
experimental investigations on fatigue of metals which are now largely
concentrated on three important areas: fatigue crack nucleation, short
crack growth and long crack propagation. The main differences
concerning the short cracks and long cracks mechanical investigation
analysis have been presented.
Keywords: fatigue, short cracks, long cracks
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On a New Optical Transducer
Cornel Bit
This paper presents a new type of mechano – optical force transducer which
to be used in different mechanical experimental investigations. This
transducer has been integrated within a mechanical modulus, providing a
useful tool for this kind of measurements. The use of optical methods for
the elastic contact measurements has several important advantages.
Keywords: transducer, mechanooptical contact, force measurements
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Fatigue, Wear and Cracking of Dental Materials
Traian Eugen Bolfa
Evaluation of the method of failure and crack propagation in dental
metals, ceramics and polymer composite materials associated with occlusal
activity are associated with contact, twisting and sliding modes.
Such loads can result in various combinations of damage due to fatigue
and wear. In order to increase sustainability and longevity the dental
materials must demonstrate sufficient strength to dynamic stresses. In
the case of masticatory forces associated with high contact tensions,
the contact area of the superficial layer is under a state of specialcomplex
voltage. Variations in the material or the structure, impurities,
scratches and voids can directly influence the structural integrity of the
material and result in microscopic cracks. These cracks propagate under
repeated cyclic loading leading to dental restoration failure.
Keywords: cracking, fatigue strength, dental composites, implants
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The Hill Chart Calculation for Francis Runner Models
using the HydroHillChart  Francis Module Software
Adelina Bostan,
Nedelcu Dorian,
Florin PerisBendu
In practice, for the design of hydraulic turbines, laboratory tests
performed on reduced scale models of turbines are recommended. The
optimisation of a turbine model requires extensive experimental research
on several variants of geometry, the improvement of efficiency at an industrial
scale which will lead to substantial economic benefits because of
the extended life of the turbine. Warranty conditions arisen from model
tests will be verified by additional tests performed on industrial prototypes
at specific points agreed between the supplier and the customer. The
purpose of these tests is the experimental determination of the
relationships between the basic parameters of the operating turbine for
different operating conditions. The graphic expression of these
relationships represent the hill chart of the turbine which is valid for the
whole turbine family similar to the tested model.
Keywords: turbine, runner, Francis, hill chart
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The Hill Chart Calculation for Pelton Runner Models
using the HydroHillChart  Pelton Module Software
Adelina Bostan,
Nedelcu Dorian,
Florin PerisBendu
The Pelton turbines industrial design is based on the hill chart characteristics
obtained by measuring the models. Primary data measurements used
to obtain the hill chart can be processed graphically, by hand or by using
graphic programs respectively CAD programs; the HydroHillChart  Pelton
module software is a specialized tool in achieving the hill chart, using interpolation
cubic spline functions. Thereby, based on measurements of
several models of Pelton turbines, a computerized library, used to design
industrial Pelton turbines can be created. The paper presents the universal
characteristics calculated by using the HydroHillChart  Pelton module
software for a series of Pelton runners.
Keywords: turbine, runner, Pelton, hill chart
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Performance of Helical Coil Heat Recovery
Exchanger using Nanofluid as Coolant
Navid Bozorgan
Nanofluids are expected to be a promising coolant condidate in
chemical processes for heat transfer system size reduction. This paper
focuses on reducing the number of turns in a helical coil heat recovery
exchanger with a given heat exchange capacity in a biomass heating
plant using ?Al2O3/ndecane nanofluid as coolant. The nanofluid flows
through the tubes and the hot nhexane flows through the shell. The
numerical results show that using nanofluid as coolant in a helical coil
heat exchanger can reduce the manufacturing cost of the heat
exchanger and pumping power by reducing the number of turns of the
coil.
Keywords: Nanofluid, Coil heat exchanger, Overall heat transfer coefficient,
Number of turns in helical coil
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Numerical Methods Application for Reinforced Concrete
ElementsTheoretical Approach for Direct Stiffness Matrix Method
Sergiu Ciprian Catinas
A detailed theoretical and practical investigation of the reinforced concrete
elements is due to recent techniques and method that are implemented
in the construction market. More over a theoretical study is a
demand for a better and faster approach nowadays due to rapid development
of the calculus technique. The paper above will present a study
for implementing in a static calculus the direct stiffness matrix method
in order capable to address phenomena related to different stages of
loading, rapid change of cross section area and physical properties. The
method is a demand due to the fact that in our days the FEM (Finite
Element Method) is the only alternative to such a calculus and FEM are
considered as expensive methods from the time and calculus resources
point of view. The main goal in such a method is to create the moment
curvature diagram in the cross section that is analyzed. The paper
above will express some of the most important techniques and new
ideas as well in order to create the moment curvature graphic in the
cross sections considered.
Keywords: manipulating of the stiffness matrix; direct stiffness matrix
method; numerical methods; initial stress link between stiffness matrix
and initial strain
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Applications of Rotational Stiffness in Numerical
Methods for Reinforced Concrete Elements Subject to Horizontal Efforts
Sergiu Ciprian Catinas
A detailed investigation of the RC elements subject to horizontal forces
and the effect of the rotational stiffness were conducted in this paper
by using numerical methods. Since the early ‘1960 this technique become
used by engineers but only in the last decade, due to the development
of the computing machines the method was used on a large
scale. The paper deals with a technique. The paper deals with a summary
of recent techniques in manipulating the stiffness matrix of the
constitutive materials in efficiently solving problems related to connection
between horizontal forces and rotational stiffness. The paper propose
some practical methods deducted from theoretical formulation of
the stiffness matrix and propose new formulation of the stiffness matrix
for this completely applicable to the new technique. At last the paper
analyses a three level RC structure using a FEM based computer soft
with the method proposed and delivers the results.
Keywords: manipulating of the stiffness matrix; rotational stiffness;
numerical methods; horizontal forces; link between rotational stiffness and horizontal forces
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Influence at Work Distance between the Sonotrode
and Specimen to Cavitational Erosion
ReluCostel Ciubotariu,
Doina Frunzaverde,
Evelina Roxana Secosan,
Viorel Campian,
MarianDumitru Nedeloni
The paper presents the results of cavitation erosion tests performed on
five samples from pure aluminum using the vibratory method with
stationary specimen. The main purpose of this research is for determine
which is the distance between the sonotrode and specimen
favorable for an aggressive cavitational attack. For this, has been calculated
the Mean Depth of Erosion (MDE) and the cavitation erosion rate
(Vec). After that the specific curve for Vec has been analytically processed.
Keywords: cavitational erosion, sonotrode, aluminium
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Tests Performed on Hydraulic Turbines at Commissioning
or after Capital Repairs. Part I. Tests Performed on a 78MW Francis Turbine
Adrian Cuzmos,
Viorel Campian,
Doina Frunzaverde,
Cosmin Dumbrava,
AnaMaria Budai
The paper presents the tests recommended by the standards to be performed
on a hydraulic turbine on commissioning, after repair works or
refurbishment, and the manner in which these tests were executed in a
hydro power plant equipped with a 75MW Francis turbine and the results
obtained.
Keywords: tests on the hydro units commissioning, index tests, Francis
turbine, power ejects, turbine commissioning
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Tests Performed on Hydraulic Turbines at Commissioning
or after Capital Repairs. Part II. Tests Performed on a 6.5 MW Kaplan Turbine
Adrian Cuzmos,
Viorel Campian,
Doina Frunzaverde,
Cosmin Dumbrava,
Damaschin Pepa
The paper presents the tests performed on a hydraulic turbine on
commissioning, the devices, test methods and the results obtained
from the respective tests, as well as the conclusions and recommendations
resulted from these tests. This kind of tests can be performed for
the verification of guarantees.
Keywords: tests at hydro units commissioning, index tests, Kaplan
turbine, power ejects
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Designing a Transcode of B.C.D. in S.B.C. and Study
its Function Using Software Electronic Workbench
Silviu Draghici,
Eugen Raduca,
Cristian Rudolf
The transcoder we have set out to synthetize and to simulate in this
paper is important due to the fact that it brings into discussion and also
presents the family of weighted and unweights binary decimal codes,
presented in binary sequences of 4 bits each. Some of these are used
even today with great success in the technique of data transmission,
especially in recognition and access keys to certain dedicated programs
and soft wares. The binary symmetric code is among the first binary
decimal weighted codes, which has been the basis for the creation and
development of other such codes. Therefore we have set out to design
and simulate such a transcoder.
Keywords: transcoder, binary symmetric code, binary decimal code, electronic
workbench
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transcoder, binary symmetric code, binary decimal code, electronic
workbench
Mohammad Etemadi,
Fakhri Etemadi,
Tayeb Pourreza
Using natural element method (NEM), the buckling and the free vibration
behaviors of moderate thick plates is studied here. The basis of
NEM is natural neighbors and Voronoi cells concepts. The shape functions
of nodes located in the domain is equal to the proportion of
common natural neighbors area divided by area that related by each
Voronoi cells. First step in analyzing the moderate thick plates is identification
boundaries. This is done by nodes scattering on problem domain.
Mindlin/Reissner theory is used to express the equations of moderate
thick plate. First and second order shape functions obtained from
natural element method are used to discretize differential equations.
Using numerical integration on whole discrete equations of domain,
stiffness, geometry and mass matrices of plate are obtained. Buckling
loads and vibration modes are expressed by substituting these matrices
in plate equations of motions. Arbitrary shapes of plate are selected for
solution. Comparing the results of the current approach with those obtained
by other numerical analytical methods, it is shown that natural
element method can solve problems with complex areas accurately.
Keywords: natural vibration, buckling, natural elements, Voronoy cells
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Experimental Generation of the Intersection Curve
of Two Cylinders: An Algorithm Based on a New Paradigm
Ioan Halalae,
Patrik Silvester Bojan
Computational Geometry is currently using approximation techniques
based on convex polygons, with good results in some topics, but with
severe limitation of applicability. In this paper we present the first step
of a larger project, aiming to lead us to the plane projection of a 3D
surface obtained by intersecting two cylinders (a very frequent problem
in obtaining the stencils for welded ensembles). As a first step, we present
an algorithm for experimentally obtaining the intersection curve of
two cylinders. The new paradigm and also the fundamentally new aspect
of our project is that we construct our algorithm by simulation of
the analytical relations describing the curve, and not by approximation
using convex polygons.
Keywords: Computational Geometry, experimental generation, cylinders
intersection, SolidWorks
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Dynamic Research of the Flexible Wheel of a Double
Harmonic Gear Transmission
Draghita Ianici,
Sava Ianici
The paper presents the results of a dynamic research of the flexible
wheel of the double harmonic gear transmission, by determining the
state of strain and stress of its wall, in cases the wheel is deformed by
a mechanical waves generator with: two rolls, two eccentric discs and
cam. The dynamic research involves modelling and the numerical
simulation of flexible wheel, by using the finite element method, with
the help of SolidWorks Simulation program in elastic range.
Keywords: flexible wheel, double harmonic gear transmission, simulation,
displacement, stress
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flexible wheel, double harmonic gear transmission, simulation,
displacement, stress
Draghita Ianici,
Sava Ianici
The paper presents the design construction and functioning of a new
type of harmonic gear transmission named double harmonic gear
transmission (D.H.G.T.). In the second part of this paper is presented
the dynamic testing of the double harmonic gear transmission, which is
based on the results of the experimental researches on the D.H.G.T.
The authors present the results of experimental research, enabling a
scientific interpretation of the dynamic behaviour of the D.H.G.T., on
the mechanical efficiency and the stress state of flexible wheel.
Keywords: double harmonic gear transmission, flexible toothed wheel,
constructive design, dynamic testing, stress, efficiency
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Sensitivity Modeling and Evaluation of Evapotranspiration
Effects on Flow Discharge of River Owena in Nigeria
P.O Idogho,
Olotu Yahaya
Analysis of discharges, precipitation and temperature and some other
meteorologicalhydrological variables from 19962011 at the section of
Owena River Basin. The evaluation, correlations, and the relationship
between precipitation and discharge time series indicate a strong
relationship. Minimum discharge values of 0.8 m3/s and 1.2 m3/s were
observed in January and December and these values correspond to
rainfall depth of 1.4 mm and 8.2 mm respectively. The average annual
rainfall, river discharge were computed as 1,306.7 mm, 1,165 m3/s and
mean temperature and evaporation of 31.1oC and 4.6 mm.
Evapotranspiration computation using pan evaporation model
overestimated the evapotranspiration values by 0.5 mm and 0.21 mm
over IHACRES and CROPWAT model for the total period of 15year.
Integration of the simulation outputs would be veritable in creating
realisticrobust water management system for domestic and
agricultural applications.
Keywords: Precipitation, Discharge, Evapotranspiration, Temperature,
Observed, Simulated
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Automated Measurement for Sensitivity Analysis of
RunoffSediment Load at Varying Surface Gradients
Imanogor P.A.,
Ovibiagele Umahon,
Ugbodaga M.E.,
Omholua A.O.
Direct measurement of surface runoff is often associated with errors
and inaccuracies which results to unreliable hydrological data. An
automatic Runoffmeter using tipping buckets arrangement calibrated
to tip 0.14 liter of runoff water per tip with an accuracy of ± 0.001 litre
was used to measure surface runoff from a steel bounded soil tray of
dimension (1200 mm X 900 mm X 260 mm) filled with sand loamy to
the depth of 130 mm and inclined at angle (00, 50 ,120 and 150)
horizontal to the instrument. The effect of varying angles of inclination
on runoff intensity, sediment loss rate and sediment loss is significant
at 5 % confidence level, while surface runoff is not significant at 5 %
confidence level. Total highest sediment loss of 458.2 g and 313.4 g
were observed at angle 150 and 120 respectively. Total surface runoff
of 361.5 mm and 445.8 mm were generated at inclined angle of 00 and
50, while at angle 120 and 150, 564.3 mm and 590.0 mm of surface
runoff were generated. In addition, runoff intensity and sediment loss
rate were highest at angle 150, while the lowest values of 1.5mm/min
and 5.43 g/min were obtained at angle of inclination 50. The results
showed that strong relationship existed among the hydrological
variables as a result of subjecting the steel bounded soil tray to
different angles of inclination. Such results would provide useful data
for the running of physicsbased deterministic model of surface runoff
and erosion which will be useful for the design of hydrological
structures, land use planning and management.
Keywords: Surface runoff, Sediment yield, Runoffmeter Slopes/Angle
Hydrological variables, Soil tray, Rainfall
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Surface runoff, Sediment yield, Runoffmeter Slopes/Angle
Hydrological variables, Soil tray, Rainfall
Meisam Khaloei,
Hossein Okhovati,
Navid Bozorgan
The energy efficiency and exergy efficiency of recommended
photovoltaic (PV) array are calculated for Kerman climate. Since energy
efficiency and exergy efficiency of PV array is dependent on weather
conditions, the recommended PV array energy and exergy have been
analyzed in various months of the year to be used in Kerman climate.
Also, the wind speed impact on exergy efficiency has been studied in
this research. The simulated results were compared to experimental
results to confirm the validity of employed relationships and a good
agreement was observed between them. Since the model’s results
match those of experiments, the model presented in this paper can be
used for various weather conditions. An important result of the
research was higher accuracy of exergy efficiency calculation of present
model relative to past models. Also, energy efficiency and exergy
efficiency were almost identical for various months of the year and the
PV array can be used to produce a part of required electric power in
Kerman climate throughout the year. The annual averages of exergy,
energy, and electrical efficiencies in Kerman climate are 12.03%,
16.27%, and 12.14%, respectively.
Keywords: photovoltaic array, energy, exergy, Kerman
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The Solidification Study of the Antifriction SnSb
Alloy
CincaIonel Lupinca,
Constantin Marta
The solidification study of the antifriction SnSb alloy (HM07) cast on a
steel bearing plate in order to obtain bimetallic bearings sized
330xF220 is presented in this paper, where the solidification study of
the antifriction alloy is also reflected, using a corresponding simulation
software (AnyCasting 10). The paper also contains, on the basis of pictograms
regarding the solidification simulation study of the HM07 alloy
and the metallographic structures realized on the component parts of
the bearing and with the help of the electronic microscope and of the
scanning electronic microscope, constructive conclusions for production
are presented in order to help diminish losses of flaw castings.
Keywords: bimetallic bearing, antifriction alloy, solidification
simulation
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Pbimetallic bearing, antifriction alloy, solidification
simulation
Feiza Memet
Regarding thermodynamics, the perception of students is that unlike
the first law, the second law has not simple statements. Despite of this,
the first two laws are related to each other and their combination
shows the influence of entropy on energy. The understanding of the
second law is the path to student knowledge related to the increase in
entropy and the decrease of the capacity of energy to do useful work
or energy. This paper describes an experiment carried out in Constanta
Maritime University (CMU), with students enrolled in Electromechanics
Faculty, in the second year of study, which reveals the need to enrich
the traditional course of Thermodynamics, in order to increase the
ability of students to deal with the second law and the concept of
entropy.
Keywords: entropy, second law, understanding, volunteers
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HydroHillChart – Francis module. Software used to
Calculate the Hill Chart of the Francis Hydraulic Turbines
Nedelcu Dorian,
Adelina Bostan,
Florin PerisBendu
The paper presents the Hydro Hill Chart  Francis module application,
used to calculate the hill chart of the Pelton, Francis and Kaplan hydraulic
turbine models, by processing the data measured on the stand. After describing
the interface and menu, the input data is graphically presented
and the universal characteristic for measuring scenarios ao=const. and
n11=const is calculated. Finally, the two calculated hill charts are compared
through a graphical superimposition of the isolines..
Keywords: turbine, Francis, runner, hill chart, Python
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HydroHillChart – Pelton module. Software used to
Calculate the Hill Chart of the Pelton Hydraulic Turbines
Nedelcu Dorian,
Adelina Bostan,
Florin PerisBendu
The paper presents the HydroHillChart  Pelton module application,
used to calculate the hill chart of the Pelton hydraulic turbine models, by
processing the data measured on the stand. In addition, the tools offered
by the application such as: interface, menu, input data, numerical and
graphical results, etc. are described.
Keywords: turbine, Pelton, runner, hill chart, Python
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The Influence of Various Operation Modes on Diesel
Passenger Cars CO2 Emissions
Arina Negoitescu,
Adriana Tokar
The amount of emissions released into the atmosphere by polluting
sources was significantly reduced due to the limitations introduced by
the EU. Since one of the main sources affecting air quality is the car,
researches regarding the influence of various factors on exhaust emissions
are carried out. As CO2 is the main pollutant responsible for the
greenhouse effect, the article treats the influence of vehicle load and
traffic levels, running modes, the electric consumer’s utilization, and
driving style on CO2 emissions for cars equipped with diesel engine.
The results from the conducted study can contribute to adopt solutions
in order to decrease the concentration of CO2 emissions from cars
equipped with diesel engines.
Keywords: CO2, passenger car, greenhouse effect, operation mode,
diesel engine
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Modelling Water SupplyBilling and Collection Systems for Effective Utility Distribution
Olotu Yahaya,
Unuigbe O.M.,
Eleta Paul.O.,
Stephen A.O.
TSafe drinking water is a strong constraint to the attainment of Millennium Development Goals by 2020. The water supply coverage of 38.3% of the total population corresponds to 45 litres per person and an average supply period of 3.5 hours daily. This further explains the degree of waterstress in Ikare. Annual nonrevenue of 18.3% represented $6.2 million USD which was lost to physical water loss, thus leading to gradual increase in operation ratio value of 1.05. Chlorination water treatment is cost effective for large water scheme than ultraviolent (UV) with a price index of $ 0.01 per 1m3 of water. The predicted cost for plant with 5 million m3 capacity. Increasing water supply coverage requires the reduction of nonrevenue water and creates effective tariff system.
Keywords: NRW, Supply, Water, Price, Coverage, Loss, Ratio, Cost, Population
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Estimation of Reference Melon CropEvapotranspiration using Eto[PanFao/Penman] and Cropwat Models
Olotu Yahaya,
Evboifo Nathaniel,
Okafor M.C.,
Ayilaran C.I.
Aiming at contributing to an adequate management of water resources, accurate estimation of reference evapotranspiration (ETo) using evaporation pan, FAOPenman and CROPWAT model is very important for the computation of Egusimelon crop evapotranspiration (ETc) at different stages of crop growth and development. The study was carried out at Research and Experimental Farm of Auchi Polytechnic, Auchi with area of 6.45 m2. Measured daily evaporation depth and weather parameters for 52day was used to compute reference evapotranspiration using evaporation pan, derived FAOPenman and CROPWAT version 8.1 models. The maximum and minimum of EToPan, EToFAOPenman are 4.1 mm; 5.7 mm and 3.5 mm; 4.2 mm. These values were applied to compute maximum and minimum cropevapotranspiration (ETc) at initial crop developmental stage as 3.4 mm; 0.68 mm respectively. The maximum and minimum intermediate and maturity values for EToPan, EToFAOPenman and ETc; 4.0 mm;0.7 mm, 3.9 mm;0.5 mm ,3.4 mm;0.68 mm and 0.7 mm;3.0mm; 0.6 mm;4.1 mm, 0.46 mm;3.25 mm respectively. The melon crop and evaporation pan coefficient for the three different stages are 0.15; 0.85; 0.60 and the pan coefficient ranged from 0.71 to 1.00 and total rainfall and irrigation depths were computed to 226.9 mm and 46.7mm.
Keywords: Reference evapotranspiration (ETo), Crop evapotranspiration (ETc), CROPWAT, Rainfall, Irrigation, FAOPenman, Computation, Crop coefficiente
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Optimisation of the Startup and Operation Regimes
of Cooling Water Pumps of a HighPower Hydro Generator
Ioan Padureanu,
Marcel Jurcu,
Ladislau Augustinov,
Cornel Hatiegan,
Eugen Raduca,
Laurentiu Padeanu
It is necessary to make sure that the operation of cooling installations
of hydro generators could be made in conditions of enhanced security
so that the probability of defects occurrence during their exploitation be
practically null. The asynchronous regime of direct network start up is
accompanied by very high values of the startup current, associated
with important voltage drops on supply cables, which results in the extension
of the motor starting time. The present paper shows an efficient
method of driving the cooling water pumps by the supply of electric
driving motors with variable frequency.
Keywords: hydro generator, optimisation, asynchronous motor,
pumps, variable efficiency
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Implementation of an Automatic System for the
Monitoring of Startup and Operating Regimes of the Cooling Water Installations of a Hydro Generator
Ioan Padureanu,
Marcel Jurcu,
Ladislau Augustinov,
Cornel Hatiegan,
Eugen Raduca
The safe operation of a hydro generator depends on its thermal regime,
the basic conditions being that the temperature in the stator
winding fall within the limits of the insulation class. As the losses in
copper depend on the square current in the stator winding, it is necessary
that the cooling water debit should be adapted to the values of
these losses, so that the winding temperature falls within the range of
the values prescribed in the specifications. This paper presents an efficient
solution of commanding and monitoring the water cooling installations
of two highpower hydro generators.
Keywords: automatic system, monitoring, programmable automaton,
frequency converter, asynchronous motor
full text
Monitoring Systems for Hydropower Plants
Damaschin Pepa,
Cosmin Ursoniu
One of the most important issue in hydro power industry is to
determine the necessary degree of automation in order to improve the
operation security. Depending upon the complexity of the system (the
power plant equipment) the automation specialist will build a philosophy
of control following some general principals of security and operation.
Helped by the modern digital equipment, today is relative easy to
design a complete monitoring and supervising system including all the
subparts of a hydro aggregate. A series of sensors and transducers
specific for each auxiliary installation of the turbine and generator will
be provided, together with a PLC or an industrial PC that will run an
application software for implementing the security and control
algorithms. The purpose of this paper is to offer a general view of these
issues, providing a view of designing an automation & control and
security system for hydro power plants of small, medium and big power.
Keywords: automatic control, frequency and power control, principles
of monitoring in hydro power, protection and remote control of hydro
power plants
full text
Experimental Testing of Welding Saw Blade of Ribbon
Iulius Petrica,
Adrian Valentin Petrica
This paper presents the results of experimental electric welding with
pressure butt of ribbon saw blades. The analyzes and tests carried out
resulting conclusion is that this process is the best solution for the refurbishment
of these blades, provided to make a comeback heat treatment
after welding.
Keywords: saw blade of ribbon, electric welding with pressure, heat
treatmen
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Influence of the Fusing Process on the Wear and
Corrosion Properties of NiCrBSiCoatings
Evelina Roxana Secosan,
Gabriela Marginean,
ReluCostel Ciubotariu,
Doina Frunzaverde,
Viorel Campian
In this study the NiCrBSi feedstock powder was deposited by flame
spraying on to C45 steel substrate. After spraying the coated material
was differently fused at 1000°C. The microstructure evolution respectively
the phase composition was evaluated by means of scanning electron
microscopy (SEM) and by Xray diffractometry. The corrosion resistance
of the differently fused coatings was assessed by potentiodynamic
corrosion tests carried out in 3,5 % NaCl solution at room
temperature, using a saturated calomel electrode (SCE) as reference.
In addition, the variation of the friction coefficients in time for the two
tested coatings was determined using the pinondisk method. The investigations
showed that the characteristics of the inductive remelted
coating are better in comparison with the flame fused one.
Keywords: fusing process, corrosion, selffluxing coatings, wear
full text
Solving Systems of Equations with Techniques from
Artificial Intelligence
Irina Maria Terfaloaga
A frequent problem in numerical analysis is solving the systems of
equations. That problem has generated in time a great interest among
mathematicians and computer scientists, as evidenced by the large
number of numerical methods developed. Besides the classical numerical
methods, in the last years were proposed methods inspired by
techniques from artificial intelligence. Hybrid methods have been also
proposed along the time [11, 14]. The goal of this study is to make a
survey of methods inspired from artificial intelligence for solving systems
of equations. Future works are also provided.
Keywords: systems of equations, genetic algorithms, particle swarm
optimization, artificial glowworm swarm algorithm, memetic algorithms
full text
Treatment Solutions for Rainwater Contaminated
with Various Pollutants
Adriana Tokar,
Arina Negoitescu
This study presents aspects on the environmental pollution with contaminants
difficult to manage from sources such as car parking, roads
and roofs in crowded areas that have deficient wastewater harvesting
urban networks. The contaminants washed by the rainwater that are
not collected and treated can reach directly into the natural environment.
Thus, rainwater which falls on rough surfaces, especially in car
parking and roads without drainage channels carries out various pollutants
directly into the soil and water. In order to control environmental
pollution there are presented solutions for contaminated rainwater depollution.
Keywords: rainwater, pollutant, sewage system, filtration substrate,
gutte
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Hot Water Recirculation and Control, a Solution to
Reduce Energy Consumption
Adriana Tokar,
Arina Negoitescu
TFor the energy consumption reduction in the buildings sector, EU proposes
guidelines regarding energy performance. EU Member States
must take measures to ensure the conversion of buildings into nearly
zero energy buildings, which should also include measures to optimize
installations for domestic hot water (DHW). From this point of view the
present paper deals with issues regarding hot water recirculation and
control aiming to reduce fuel consumption necessary for DHW preparation.
To this end the benefits of DHW preparation process optimization
were analyzed, in order to ensure a theoretical constant temperature
having values in a narrow domain and an efficient thermal fluid distribution
in the network for better controlling hot water temperature.
Keywords: domestic hot water, temperature, flow, energy, recirculating
pump
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Anul XXII (2015), Nr. 2
COVER
TABLE OF
CONTENTS
ARTICLES
Evaluation of Urban Renewal Strategies towards
Physical Growth of Nigeria
Aigboje Timothy
Urban Renewal Strategy (URS) is a term to denote systems employed
to revitalize, regenerate urban area and cities in general. The basic
mode acceptable worldwide are redevelopment, rehabilitation, revitalization
and reservation. This paper presents each of these mechanisms
in holistic term on one hand and discussion on areas where urban renewal
had taken place in Nigeria which as case studies is presented.
The urban renewal strategy impact on the physical growth namely
building and environmental condition of these areas is also discussed.
Therefore this research is carried out using secondary data obtained
through study and evaluated. The outcome shows that renewal activities
do displace and disrupt original inhabitant of an area and their
economic activity. However, the overall positive impact indicates rapid
growth and development both in the physical, economic structure
which alternatively accentuate physical growth of Nigeria in general.
Keywords: Redevelopment, Growth, Environmental, Physical, Impact,
Renewal
full text
Design for a Sustainability of a Commercial Product:
A Case Study of a Dynamic Loudspeaker
Alimasunya E,
Olotu Yahaya,
Abudu Mohammed
Sensitivitybased analysis carried out on the production of dynamic
loudspeakers for client (A) and (B) showed that client (A) has reliability
efficiency 0f 20.4% with 90% of Tp, 30%Ep, 50%Ecp, while client (B)
has 30%Tp, 90%Ep and 50%Ecp respectively. Sustainability of client
(B) is higher than (A) with 0.06. It has 99% and 20.1% system and
efficiency reliabilities. Client (B) has the flexibility of indoor and outdoor
which Client (A) lacks. The overall simulation analysis shows that client
(B) product is better than (A).
Keywords: Loudspeaker, Client, Efficiency, Analysis, System, Reliability,
Performance
full text
Natural Stone as Sustainable Resources in
Ecological Buildings Design
AncaAndreea Balog,
Nicoleta Cobirzan
IThe paper analyse the heat energy demand and CO2 emission of one residential building made of natural stone in order to evaluate the advantages in terms of sustainability resulted during operation phase. In this context, it was considered different constructive solution for external walls, optimizing the wall thickness by addition an supplementary layer of natural thermal insulation.
Keywords: tuff, cork, heat losses, CO2 emission, saving energy
full text
Long Silver Nanowires Synthesis by Pulsed
Electrodeposition
M.R. Batevandi,
M. Zarei,
N. Bozorgan
Silver nanowires were pulse electrodeposited into nanopore anodic alumina oxide templates. The effects of continuous and pulse electrodeposition
waveform on the microstructure properties of the nanowire arrays were
studied. It is seen that the microstructure of nanowire is depend to pulse
condition. The off time duration of pulse waveform enables to control the
growth direction of Ag nanowires.
Keywords: nanoporous alumina, pulse electrodeposition, silver nanowire
full text
Using Four Model for Predicting the Thermal
Conductivity in the Analysis of the Efficacy of Nanofluid in a DoubleTube Heat Exchanger
Navid Bozorgan
In the present paper, CuO/EthyleneGlycol (EG) nanofluid with dp=29
nm and volume fractions of nanoparticles ( f = 110% ) as coolant has
been used in a doubletube heat exchanger to optimize its heat
transfer performance under laminar flow conditions. The hot solvent
inlet heat exchanger must be cooled down with a specified amount. At
first, the heat transfer relations between hot solvent and nanofluid as
coolant in the heat exchanger have been investigated theoretically.
Subsequently, the heat transfer coefficient, overall heat transfer coefficient,
friction factor, pressure drop and pumping power for CuO/EG
nanofluid calculated based on four experimental models presented to
predict the thermal conductivity of the CuO/EG nanofluid. Moreover,
the heat transfer area is optimized by using the CuO/EG as coolant in
the heat exchanger to reject this same amount of heat.
Keywords: Nanofluid, Doubletube heat exchanger, thermal conductivity coefficient, Heat transfer performance
full text
Identification of the Opportunities for Future
Development of Tidal Energy
Navid Bozorgan,
MohammadRezaBatevandi,
Mohadeseh Miri
An overview of status of development of tidal energy is given in this article. To reduce the dependance on fossil fuel and imported energy
resources, the need for ocean energy is a global demand in developing
countries. The ability to directly extract from the world’s oceans may be
in the form of mechanical energy from waves, tides, or currents, or in
the form of thermal energy from the sun’s heat. This paper identifies
the opportunities for future development of tidal energy.
Keywords: Tidal energy; Tidal barrage; Tidal turbine; Power
full text
Estimation of Lifetime Duration for a Lever Pin of
Runner Blade Operating Mechanism using a Graphic–analytic Method
AnaMaria Budai,
Viorel Campian,
Vasile Cojocaru,
Zoltan Korka,
Cosmin Dumbrava
In this paper are presented a graphic  analytic method that can be
used to estimate the fatigue lifetime duration for an operating mechanism
lever pin to a Kaplan turbine. The presented calculus algorithm is
adapted from the one used by Fuji Electric to made strength calculus in
order to refurbish a Romanian hydropower plant, equipped with a Kaplan
turbine. The graphic part includes a 3D fatigue diagram for rotating
bending stress designed by Fuji Electric specialists.
Keywords: fatigue, pin, algorithm, Kaplan, lifetime duration
full text
Calculation of Digital Control Circuits using Scilab
Environment
Petru Chioncel,
Eugen Raduca,
Cristian Paul Chioncel,
Nicoleta Gillich
The paper presents the computing of digital control circuits using Scilab
environment. It exemplifies the influence of the sampling time in case
of a transfer system described by a PT3 element composed of one PT1
and one PT2 element. For a continuous control system, the transfer
function in z is computed and replaced with a digital control system.
The presented calculation, done in Scilab, highlights the test responses
of the process evidencing the systems performances.
Keywords: transfer function in z, sampling time, Scilab environment
full text
An Extension of the BurridgeKnopoff Model for Friction
Veturia Chiroiu,
Dan Dumitriu
The paper presents an extension of the BurridgeKnopoff (BK) model
with an additional kinetic equation for the friction force in order to
reproduce the both the velocity weakening friction between the tire and
the road and the increase of static friction with time when the car is not
moving. The BK was initially proposed to investigate statistical
properties of earthquakes. In this model the sliding force decreases
monotonously from a reference value, and the static friction can have
negative values to prevent back sliding. The stability of the system is
affected and the sliding regime at small sliding velocities and large
stiffness cannot be reproduced. The extended model BK assures the
stability of the diagram slidingstationary sliding, and correctly
reproduces the stability diagram for sliding friction under various
loading conditions.
Keywords: friction, BurridgeKnopoff, model, stability
full text
Coil Springs Layer Used to Support a Car Vertical
Dynamics Simulator and to Reduce the Maximum Actuation Force
Dan N. Dumitriu,
Cornel Lala
A Danaher Thomson linear actuator with ball screw drive and a realtime control system are used here to induce vertical displacements under
the driver/user seat of an inhouse dynamic car simulator. In order
to better support the car simulator and to dynamically protect the actuator’s
ball screw drive, a layer of coil springs is used to support the
whole simulator chassis. More precisely, one coil spring is placed vertically
under each corner of the rectangular chassis. The paper presents
the choice of the appropriate coil springs, so that to minimize as much
as possible the ball screw drive task of generating linear motions, corresponding
to the vertical displacements and accelerations encountered
by a driver during a real ride. For this application, coil springs with
lower spring constant are more suited to reduce the forces in the ball
screw drive and thus to increase the ball screw drive life expectancy.
Keywords: dynamic car simulator, vertical linear actuator, ball screw drive, coil springs layer, spring constant optimization
full text
VibrationBased Structural Health Monitoring: TheoreticalFoundations and Experimental Validation on
Reinforced Concrete Beams
Anthony Nkem Ede,
Ben Uchechukwu Ngene,
Gideon Olukunle Bamigboye
Quick identification of damages in structures is of great importance to engineers. Among the various techniques available for the evaluation of
reinforced concrete structural integrity, nondestructive tests method
remain a viable one as its use can lead to speedy decisions that bring
savings on repairs or replacement of damaged reinforced concrete
structures. This research uses modal parameterbased non destructive
tests to assess damages in reinforced concrete beams under static
load. Fourpoint static loadings were applied to the 3 RC beams to induce
three damage scenarios. After each static loading, a dynamic test
was performed to access the degree of stiffness degradation. Modal
frequencies and mode shapes obtained depicts clearly the stiffness degradations
of the beams as the severity of damages on the beams became
more pronounced. Results obtained showed that the research
procedure adopted is a smart approach for damage assessment in reinforced
concrete elements.
Keywords: Damage Assessment, Dynamic Test, NonDestructive
Tests, Reinforced Concrete Beams
full text
Vacuum Degasing of Steel used for Forged Ingots
Cristian Fanica,
Ioan Ilca,
Viorel Campian
As part of the economy, metallurgy must address the problem of product quality in all aspects, especially in view of the the usage properties and physicomechanical characteristics. The paper deals with vacuum melting
processes used to eliminate gases and inclusions from both small amounts of
molten steel and from large ingots.
Keywords: absorbed gases, flaking, brittleness, inclusions, vacuum degassing
full text
Critical Buckling Force Variation for Beams with
Discontinuities
Horia Furdui,
Andrea Amalia Minda,
GilbertRainer Gillich,
Florian Muntean
This paper introduces a method to evaluate the critical buckling force for beams with geometrical discontinuities. First the shape of the
healthy deformed beam due to axial forces is analyzed, in order to
predict the distribution of the strain energy in the first buckling mode.
Afterwards, the critical buckling forces for the similar beams with
discontinuities positioned at different locations are determined by
means of the finite element method (FEM), in order to find a similarity
between the critical force drop and the damage position. It was finally
demonstrated that it is a correlation between these two features; in
fact, the force decrease is proportional with the energy locally stored in
the beam.
Keywords: Doubleclamped beam, thermal buckling, damage
full text
Acoustical Wave Propagation in Sonic Composites
Iulian Girip,
Ruxandra Diana Ilie
The goal of this paper is to discuss the technique of controlling the mechanical properties of sonic composites. The idea is to architecture
the scatterers and material from which they are made, their number
and geometry in order to obtain special features in their response to
external waves. We refer to perfectly reflecting of acoustical waves
over a desired range of frequencies or to prohibit their propagation in
certain directions, or confining the waves within specified volumes. The
internal structure of the material has to be chosen in such a way that
to avoid the scattering of acoustical waves inside the material. This is
possible if certain bandgaps of frequencies can be generated for which
the waves are forbidden to propagate in certain directions. These bandgaps
can be extended to cover all possible directions of propagation by
resulting a full bandgap. If the bandgaps are not wide enough, their
frequency ranges do not overlap. These bandgaps can overlap due to
reflections on the surface of thick scatterers, as well as due to wave
propagation inside them growth.
Keywords: sonic composite, full bandgap, control
full text
New Comparative Study through Modal Analysis of Thin
Trapeze Shape Plates Clamped on Contour without and with Damages
Cornel Hatiegan,
MarianDumitru Nedeloni,
Cristinel Popescu,
Marius Tufoi,
Ioan Padureanu,
Cristian Rudolf
This paper presents a comparative study of four types of plates in the form of trapeze, clamped on the contour, regarding modal analysis.
After this analysis, there have been obtained the Eigen frequencies for
30 vibration modes between the limits 183.37 ÷ 1206.3 [Hz]. For these
results there has been computed the absolute variation, respectively
the relative frequency shifts of the analyzed plates.
Keywords: Comparative study, thin trapeze shape plates, clamped on contour, damages
full text
Simulation Analysis for Rainwater Harvesting and
Groundwater Withdrawal in Auchi, Nigeria
Philipa O. Idogho,
Yahaya Olotu
Shortage in supply of water for potable and nonpotable applications and
exponential world population increase is a strong constrain to Human Development
Index and socialeconomic advancement in Nigeria. ClimGen (Version
4.1.05) was used to simulate and create large dataset of annual rainfall
depth. Generated average annual rainfall from 1430 mm to 1600 mm was
subjected to varying roof plan surfaces of 250 m2; 500 m2; 1000 m2; and
2000 m2 respectively. Simulation analysis showed that an average of
5,300m3 of rainwater was harvestable and this value of water could only
meet water demand of 170 people annually. The relationship of roof plan
surface (RPS) and collected rainwater is very strong with R2= 0.84 and 0.95
respectively. Again, the volume of groundwater withdrawal increased from
12.4×104m3 to 32.7×104m3, this could only meet an annual water demand
for 10,480 people representing about 6.2% of the population in Auchi. This
development reveals that water supply from the alternative sources could
not meet up to 6.3% of total water demand in Auchi and increasing water
availability and accessibility to about 65% (31.3×105m3) coverage requires
integrated rainwater harvesting system and technicallybased groundwater
exploration mechanism.
Keywords: potable, accessibility, rainfall depth, RPS, volume,demand, integrated
full text
Development of Water Supply and Billing Systems
for Effective Utility Distribution
Philipa O. Idogho,
Yahaya Olotu
Safe drinking water is a strong constraint to the attainment of Millennium
Development Goals by 2020. The water supply coverage of 38.3% of the
total population corresponds to 45 litres per person and an average supply
period of 3.5 hours daily. This further explains the degree of waterstress in
Ikare. Annual nonrevenue of 18.3% represented $6.2 million USD which
was lost to physical water loss, thus leading to gradual increase in operation
ratio value of 1.05. Chlorination water treatment is cost effective for large
water scheme than ultraviolent (UV) with a price index of $ 0.01 per 1m3 of
water. The predicted cost for plant with 5 million m3 capacity. Increasing
water supply coverage requires the reduction of nonrevenue water and
creates effective tariff system.
Keywords: NRW, Supply, Water, Price, Coverage, Loss, Ratio, Cost,Population
full text
Tests Regarding the Transitory Regimes of Putting
off Load of the Hydroagregate
Marcel Romulus Jurcu,
Ioan Padureanu,
Laurentiu Padeanu,
Ladislau Augustinov,
Cornel Hatiegan
For high power and high revolution aggregates it is required that the
operation should take place in safe conditions, for all the running regimes.
The most difficult regimes for a hydro aggregate are the transitory
regimes. Although, these regimes generally last a rather short period
of time, for high power aggregates these regimes are accompanied
by electric and mechanic solicitations which sometimes can surpass the
admitted values. In the present paper, we present an evaluation method
of the rotating parts’ dynamic stability of the hydro aggregates in
the transitory regime of putting off load. We present the results obtained
from the recordings of putting off load and those obtained after
the dynamic equilibration of the hydro aggregate’s rotor.
Keywords: hydro aggregates, vibrations, dynamic stability
full text
RA Study Effect of Sistan Region Dust on the Aerodynamic Performance of Wind Turbine Blade
Mohadeseh Miri,
Navid Bozorgan,
Farhad Vahidinia
It is very important to establish a wind farm in the windy areas due to
the increased use of renewable energies. Sistan region is one of the
windy regions in Iran but due to the dust in the wind of this area and
adhesion property of this particles to the wind turbine blade, smoothness
of the blade surface is somewhat lost which affects its aerodynamic
performance. In this paper, the aerodynamic performance of
wind turbine blade was numerically investigated considering the roughness
height due to the sticking dust particles in the wind, change of the
attack angle, and roughness height. It compared with the experimental
results and the range of the optimum attack angle was proposed for
turbine in the Sistan region.
Keywords: Dust, wind turbine, airfoil, lift coefficient, drag coefficient
full text
A Review on Natural Convection in Nanofluid Flow
Mohadeseh Miri,
Farhad Vahidinia,
Navid Bozorgan
The Heat transfer is performed in three forms including conduction,
convection and radiation. Convection is one of the major modes which
classifies into three categories: natural, mixed or forced convection. In
recent years, much attention was given to the use of natural
convection with nanofluid in engineering application, satellite, cooling
system, solar collector etc. and many studies were conducted in this
area. This paper reviews some results of numerical, experimental and
theoretical studies in the field of natural convection heat transfer with
nanofluid and application of natural convection. Finally, some
suggestions are given for future studies in this area.
Keywords: NanoFluid, Natural Convection, Heat Transfer
full text
Natural Convection in Special Conditions ( Porous
media, Magnetic Field) in NanoFluid Flow, A Review in Recent Literature
Mohadeseh Miri,
Farhad Vahidinia,
Navid Bozorgan
Natural convection is the fundamental subject in heat transfer. So it is the matter of many theoretical and experimental researches. In recent
years, much attention was given to the use of natural convection with
nanofluid in reactor design, engineering application, cooling of
electronic equipment, aircraft cabin insulation, solar collector etc. and
many studies were conducted in this area. In this paper, a review on
the influence of parameters of magnetic field, porous media and
volume fraction of nanofluid in the natural convection on the heat
transfer, Nusselt number, entropy generation and Hartmann number
has been investigated. In the end, some suggestions have been given
for continue work.
Keywords: Natural Convection, Porous Media, Magnetic Field, Volume Fraction
full text
Localized Modes at Defects in Sonic Composites
Valerica Mosnegutu,
Ligia Munteanu
The paper discusses a sonic composite with a linear defect. Such
structures allow localization of modes in the vicinity of the line defect
with propagation along this line. The material in the vicinity of the line
behaves like frequencyspecific mirrors. The waves are trapped in a
virtual set of mirrors parallel to the defect line, and the propagation
bounce back and forth between these mirrors. The mirrors localize
waves within a finite region of the line defect, and modes are quantized
into discrete frequencies. If a mode has a frequency in the gaps, then it
must exponentially decay inside the material. In a similar fashion, if the
materials have point defects, the waves can be localized at the surface
in which these point defects are locatedntial growth.
Keywords: sonic composite, full bandgap, linear defects
full text
On the Evanescent Waves in Sonic Bandgaps
Ligia Munteanu,
Rodica Ioan
The bandgaps or the Bragg reflections occur at different frequencies
inverse proportional to the central distance between two scaterers. The
evanescent waves may converge or diverge as distance goes to infinity.
If the waves converge, they decay exponentially within the bandgaps
and sustain an evanescent mode. If the waves diverge, a defect can
terminate this exponential growth.
Keywords: sonic composite, full bandgap, evanescent waves
full text
Theoretical and Experimental Research Performed on
the Tesla Turbine  Part I
Dorian Nedelcu,
Petrica Guran,
Alexandru Cantaragiu
The paper presents the theoretical and experimental research performed on a Tesla turbine driven by compressed air and designed to equip a
teaching laboratory [1], [2]. It introduces the operating principle of the
Tesla turbine, which was invented by engineer Nikola Tesla, a turbine
which uses discs instead of blades, mounted on a shaft at a small
distance between them. The turbine geometry, results from stress and
flow calculations performed on the turbine rotor and assembly, using the
Simulation modules and SolidWorks Flow Simulation program are
presented. After designing the turbine, it becomes the subject of experimental
research to determine the curve of the speed depending on the
pressure. Also, the experimental research focuses on the behaviour of the
turbine from a dynamic point of view [3].
Keywords: turbine, Tesla, SolidWorks, Flow Simulation
full text
Theoretical and Experimental Research Performed on
the Tesla Turbine – Part II
Dorian Nedelcu,
EdwaldViktor Gillich,
Vasile Iancu,
Florian Muntean
The paper presents research made to highlight the dynamical behavior of a Tesla turbine actuated with compressed air. Since the noise and
vibration level of industrial equipment is an important concern of
nowadays industry, we focused on established the relation existing
between the angular speed and the vibration amplitude. The turbine,
designed and manufactured specially for this experiment, is simple and
consists of a casing and 16 circular disks mounted on the shaft. Due to
the inexistence of unbalanced components, a low vibration level is
presumed; experiments confirmed this hypothesis.
Keywords: Tesla, turbine, compressed air, vibration level
full text
A Modal Analysis Study of Thin Parallelogram Plates
Clamped on the Rim with and without Defects Using
the SolidWorks Program
MarianDumitru Nedeloni,
Cornel Hatiegan,
Florian Muntean,
Marcel Jurcu,
Irina Maria Terfaloaga, Petru Magheti
This paper presents the study of the modal analysis of four types of
plates in parallelogram shape, with or without defects, using the
SolidWorks program. The results obtained after this study, have
targeted the behavior of plates regarding the mesh, the deformation
scale, the resultant amplitude, the rotational speeds, respectively the
Eigen frequencies according to the vibration modes.
Keywords: Modal analysis, parallelogram plates, SolidWorks program
full text
Calibration of RainfallRainwater Capturing Mechanism
Using Integrated Water Management Model
(IWMm) in Auchi, Nigeria
Olotu Yahaya,
Alimasunya E,
Rodiya A.A.,
Olaiya S.
Accessibility of safe drinking water is a serious constraint in Auchi and
its environs. This region mainly depends on rainwater and groundwater
exploration. Sensitivity simulation analysis using structured IWRM
model shows that there is a strong relationship with the rainfall, rainwater
capture and roof plan size (RPS). Average annual rainfall of 1430
mm and 1600 mm simulated with varying roof plan surfaces (RPS) of
100 m2, 250 m2; 500 m2; 1000 m2; and 2000 m2 produced RWHI index
of 0.1, 0.24, 0.47, 0.94 and 1.89 respectively. Simulation output indicated
that an average of 5,300m3 /day of rainwater were harvestable
and this value of water could only meet daily water demand of 40,769
people. The output of statistics metrics shows a perfect match (RPS)
and harvested rainwater as R2= 0.78; 0.77 and r.m.s of 0.100 respectively.
The overall result shows that if the potential of rainwater harvest
is fullyharnessed, that will reduce the water stress and constrain in
Auchi.
Keywords: Simulation, Rainwater, Rainfall, Model, RWHI, IWRM, RPS,Output
full text
Aspects regarding the Calculation of the Dielectric
Loss Angle Tangent between the Windings of a Rated 40 MVA Transformer
Cristinel Popescu,
Cornel Hatiegan
TThe paper aims to identify how to determine the dielectric loss angle
tangent of the electric transformers from the transformer stations.
Autors of the paper managed a case study on the dielectric established
between high respectively medium voltage windings of an electrical
rated 40 MVA transformer.
Keywords: dielectrics, dielectric losses, dielectric measurements, insulation resistance
full text
The Correlation between Harmonica Indices and
Noise Indicators
Momir Prascevic,
Darko Mihajlov,
Dragan Cvetkovic
Environmental Noise Directive requires the use of common noise indicators in member countries of the European Union as physical quantities
that describe the environment noise created by different sources of
noise. The END noise indicators are expressed in decibel unit which is
logarithmic in nature, and usually complicated to explain and relatively
farremoved from perception of people. Two French organizations suggested
a new environmental noise index called Harmonica index based
on measurement data obtained by noise monitoring and take into account
both the overall environmental noise load and noise peaks from
sudden noise events. In order to determine adequacy of Harmonica indices
and relationship between the Harmonica indices and the END
noise indicators, the correlation analysis was carried out and the correlation
coefficient was determined for different combination of the Harmonica
indices and the END noise indicators. The results of the correlation
analysis on the sample of noise monitoring data in the city of Niš
are presented in this paper after overview the END noise indicators and
Harmonica index.
Keywords: Noise indicator, Harmonica index, Correlation analysis
full text
Attenuation of Road Traffic Noise by Vegetation in
Urban Spaces
Jasmina Radosavljevic,
Ana Vukadinovic,
Dejan Vasovic,
Aleksandra Petkovic
The last decades of the 20th century and the beginning of the 21st
century have been characterized by rapid urban growth of cities, which
resulted in overcrowding and the lack of land. The aftermath of such
circumstances is the construction of many buildings near the main
roads and the bus stations, which causes population exposure to
significant levels of noise. In the cities aimed at maintaining sustainable
urban environment, greenery is a key element that can be used to
approach this issue successfully. Green facades, also known as vertical
greenery systems, are becoming increasingly popular in urban areas.
Vertical green systems on the facade walls, low belts of green
vegetation and trees of different heights, widths and lengths contribute
to reducing the level of traffic noise. The ability of greenery to
attenuate noise is greater with the increasing frequency of traffic. This
paper describes the effects of certain types of vegetation on traffic
noise reduction, depending on the parameters such as: the type of
vegetation, the dimensions of the green belt, the distance from the
noise source, frequency range, etc.
Keywords: urban spaces, vegetation, traffic noise, traffic noise reduction
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Basic Concepts in the Diagnosis of Traffic Safety Installations Using Fuzzy Logic Based Models
Elisabeta Spunei,
Ion Piroi,
Florina Piroi
The diagnosis of failures in train traffic installations can be done in several ways: direct observations and measurements, software assisted
diagnosis using specific software packages, process variable monitoring
for electronically centralized installations. This work presents basic concepts
for Model Based Diagnosis (MBD) that uses fuzzy logic to analyse
the integrity of Centralized Traffic Control Installations (CTC) in train
traffic. We define the diagnosis relations to be used and show how to
apply them to train traffic security installations. Implementing these
concepts into an expert system assists maintenance operators in quick
failure diagnosis of the train traffic security installations.
Keywords: (CTC), Model Based Diagnosis, logic relations, fuzzy logic
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Computer Diagnosis of Output Light Signals
Elisabeta Spunei,
Ion Piroi,
Cristian Muscai,
Monica Rosu
Modern applications for PCs, mobile phones or tablets are increasingly
stirring the interest of users and contribute to the labour productiveness
in diverse fields. The paper presents the method of computer diagnostic
of output signals in railway stations, based on the diagrams
and diagnosis software, elaborated by the authors. The diagnostic diagrams
were drawn up by using the diagrams from the stations with
electrodynamics centralisation (CED) of the CR4 type. The software
may run on diverse modern devices and can be also adapted for other
types of CED installations. Grace to the answers to different questions
asked by the application, the possible causes of the failure or fault may
be displayed fast and accurately. The purpose of the computer diagnostic
is to reduce the normal diagnosis time.
Keywords: output light signals, diagrams, computer diagnostic
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Motion without Friction of a Particle on a Mobile
Surface with Bilateral Constraints
Nicolae–Doru Stanescu
In this paper we present the equations of motion of a particle in a multibody type form on a mobile surface. The particle is considered to be
acted by a resultant force. At this resultant, the normal reaction is also
added. The normal reaction is variable in time, even if the particle remains
at the same point of the mobile surface. An example is also presented.
Keywords: mobile surface, equations of motion, multibody, constraints
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Equilibrium without Friction of a Particle on a Mobile
Surface with Bilateral Constraints
Nicolae–Doru Stanescu
In this paper we will study the equilibrium of a particle on a mobile surface in the case characterized by bilateral constraints between the particle and the surface, and the absence of friction. Based on our previous
work, the conditions for the equilibrium are obtained. We prove
that the positions of equilibrium on a mobile surface are no longer the
same with those obtained for a fixed surface, the system could have either
other equilibrium positions, completely different, or some more
equilibrium positions, or no equilibrium position.
Keywords: mobile surface, equilibrium position, conditions of equilibrium
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Description of a Composed Seismic Isolation System
for Bridge Structures
Fanel Dorel Scheaua
From the design stage of a specific structural project, achieving a high level of safety is desired for structures, necessary to withstand dynamic
actions that could have destructive effects on the resistant structure. In
order to obtain the optimum level of safety against dynamic actions different
types of isolation systems are placed into the structural system.
The most commonly isolation method used is the base isolation method
through which a disconnection between foundation and superstructure
can be achieved. The isolation method presented uses special mechanical
systems which are able to consume an amount from dynamic
actions energy through their action. This study presents a base isolation
method for building structures along with an overview of the different
system solutions used to achieve the desired objective: ensuring
a high level of safety for a bridge or viaduct structural type during a
seismic event.
Keywords: elastomeric bearing, energy dissipation, seismic isolation
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Numerical Investigation of Nanofluid Mixed
Convection in an Inclined Channel and Predicting Nusselt Number with Artificial Neural Networks
Hamid Teimouri,
Navid Bozorgan
Artificial Neural Networks (ANNs) are used as a new approach in
determination of Nusselt number of copper water nanofluid in an
inclined channel with three heat sources. For training the ANNs, the
simulation results are obtained by Finite Volume Method (FVM). The
effects of independent parameters, including the Reynolds number,
Rayleigh number, inclination angle, and the solid volume fraction of
nanoparticles, on the streamlines, isotherm lines, and the average
Nusselt number have been studied. Artificial neural networks (ANN)
used to find a relation involve independent parameters for estimating
the Nusselt number. The back propagationlearning algorithm with the
tangent sigmoid transfer function is used to sequence the ANN. Finally,
analytical relations for the nanofluid mixed convection in a channel are
derived from the available ANN. It is shown that the coefficient of
multiple determination (R2) between the FVM and ANN predicted values
is equal to 0.99866, maximum relative error is less than 5.9128% and
mean square error is 1.13×103. Results show that the obtained
formulation is obviously within acceptable limits.
Keywords: NanoFluid, Finite Volume Method, Artificial Neural Networks, Channel, Mixed Convection
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Scada Systems – Control, Supervision and Data Acquisition for the Power Plants Settled on a Stream
(Part 1)
Cosmin Ursoniu,
Damaschin Pepa
Scada (supervisory control and data acquisition) is a complex system
that supervises and control an industrial process and performs several
functions. A human machine interface will also be presented and how
the process in a power plant is controlled and supervised through it by
the operator. The main screen will be described (which is a global view
of the hydro unit) and what the operator can see and what he can
press to control the power plants process also a few more screens will
be presented for auxiliary installations and it will be described what the
operator can see and what he can do to control the installation.
Keywords: Scada Systems, Power Plants, energy
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Scada Systems – Control, Supervision and Data Acquisition for the Power Plants Settled on a Stream
(Part 2)
Cosmin Ursoniu,
Damaschin Pepa
Scada (supervisory control and data acquisition) is a complex system
that supervises and controls an industrial process and performs several
functions. A human machine interface will also be presented and how
the process in a power plant is controlled and supervised through it by
the operator. The main screen will be described (which is a global view
of the hydro unit) and what the operator can see and what he can
press to control the power plants process also a few more screens will
be presented for auxiliary installations and it will be described what the
operator can see and what he can do to control the installation.
Keywords: Scada Systems, Power Plants, energy
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Numerical Investigation of Turbulent Forced
Convection Nanofluids Inside an Annulus
Farhad Vahidinia,
Mohadeseh Miri,
Navid Bozorgan
Turbulent forced convection heat transfer of Al2O3water nanofluid has been studied numerically under uniform heat flux on the inner and
outer walls in an annulus with rough tubes. Solid nanoparticles diameter
were considered to be 18, 32, and 67 nm. Twodimensional elliptic
governing equations were used and the secondorder upstream difference
scheme and finite volume method were used for the discretization
of governing equations. SIMPLEC algorithm has been established the
relationship between pressure and velocity. The results demonstrated
that the surface friction coefficient increases both in the inner and
outer wall of the heat exchanger by increasing the diameter of
nanoparticles. On the other side, the Nusselt number of nanofluid is
greater than the base fluid for a given Reynolds number and nanoparticle
volume fraction. Also, the Nusselt number decreases in the inner
and outer wall with increasing the diameter of nanoparticles.
Keywords: Turbulent flow, Forced convection, Annulus, Nanofluid
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Book review,Optimum Design of Steel Structures,
Proiectarea optima a structurilor metalice
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