Analele Universităţii
"Eftimie Murgu"
Fascicula de Inginerie
ISSN-L 1453-7397
   Printed version ISSN 1453-7397
   Online version  ISSN 2344-4568

                                                            Issues > Current issue
  About the Journal
  Editorial Board
  Scientific Board
  Call for papers
  Current Issue
Indexed by
 Academic Journals Database
 British Library

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.


Anul XXII (2015), Nr. 1




Performance Evaluation of an Egusi-melon 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 water-borne diseases and low washing output. In this study, Egusi-melon washing machine was fabricated in the Department of Agricultural and Bio-Environmental 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: Egusi-melon, feedrate, washing efficiency, washing capacity, sieve size (EMWV)

full text

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

full text

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

full text

Special Cases Solution of the Transport Problem

Olga-Ioana 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

full text

The Transport Problem utilized for Machines Optimal Allocation

Olga-Ioana 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

full text

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: machine-tool, CNC, CAD, CAM, CAE

full text

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

full text

BOn the Numerical Modeling of Confined Masonry Structures for In-plane 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

full text

Contributions in the Preparation and Processing of Composite Material Type Silumin 3 - Reinforced Matrix with S235JR Steel Mesh

Remus Belu-Nica, Relu-Costel Ciubotariu

In the paper are presented concrete data on developing technological batches of metal composite material (MCM) type Silumin 3-reinforced 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 150-300 µm, density 2300 kg/m3 and melting point 1240°C.

Keywords: composite materials, destructive testing program, microstructural examinations

full text

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

full text

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, mechano-optical contact, force measurements

full text

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

full text

The Hill Chart Calculation for Francis Runner Models using the HydroHillChart - Francis Module Software

Adelina Bostan, Nedelcu Dorian, Florin Peris-Bendu

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

full text

The Hill Chart Calculation for Pelton Runner Models using the HydroHillChart - Pelton Module Software

Adelina Bostan, Nedelcu Dorian, Florin Peris-Bendu

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

full text

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/n-decane nanofluid as coolant. The nanofluid flows through the tubes and the hot n-hexane 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

full text

Numerical Methods Application for Reinforced Concrete Elements-Theoretical 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

full text

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

full text

Influence at Work Distance between the Sonotrode and Specimen to Cavitational Erosion

Relu-Costel Ciubotariu, Doina Frunzaverde, Evelina Roxana Secosan, Viorel Campian, Marian-Dumitru 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

full text

Tests Performed on Hydraulic Turbines at Commissioning or after Capital Repairs. Part I. Tests Performed on a 78-MW Francis Turbine

Adrian Cuzmos, Viorel Campian, Doina Frunzaverde, Cosmin Dumbrava, Ana-Maria 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 75-MW Francis turbine and the results obtained.

Keywords: tests on the hydro units commissioning, index tests, Francis turbine, power ejects, turbine commissioning

full text

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

full text

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

full text

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

full text

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

full text

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

full text

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

full text

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 meteorological-hydrological variables from 1996-2011 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 15-year. Integration of the simulation outputs would be veritable in creating realistic-robust water management system for domestic and agricultural applications.

Keywords: Precipitation, Discharge, Evapotranspiration, Temperature, Observed, Simulated

full text

Automated Measurement for Sensitivity Analysis of Runoff-Sediment 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 Runoff-meter 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 physics-based 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, Runoff-meter Slopes/Angle Hydrological variables, Soil tray, Rainfall

full text

Surface runoff, Sediment yield, Runoff-meter 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

full text

The Solidification Study of the Antifriction Sn-Sb Alloy

Cinca-Ionel Lupinca, Constantin Marta

The solidification study of the antifriction Sn-Sb 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

full text

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

full text

HydroHillChart – Francis module. Software used to Calculate the Hill Chart of the Francis Hydraulic Turbines

Nedelcu Dorian, Adelina Bostan, Florin Peris-Bendu

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

full text

HydroHillChart – Pelton module. Software used to Calculate the Hill Chart of the Pelton Hydraulic Turbines

Nedelcu Dorian, Adelina Bostan, Florin Peris-Bendu

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

full text

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

full text

Modelling Water Supply-Billing 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 water-stress in Ikare. Annual non-revenue 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 non-revenue water and creates effective tariff system.

Keywords: NRW, Supply, Water, Price, Coverage, Loss, Ratio, Cost, Population

full text

Estimation of Reference Melon Crop-Evapo-transpiration using Eto[Pan-Fao/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, FAO-Penman and CROPWAT model is very important for the computation of Egusi-melon 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 52-day was used to compute reference evapotranspiration using evaporation pan, derived FAO-Penman and CROPWAT version 8.1 models. The maximum and minimum of EToPan, EToFAO-Penman are 4.1 mm; 5.7 mm and 3.5 mm; 4.2 mm. These values were applied to compute maximum and minimum crop-evapotranspiration (ETc) at initial crop developmental stage as 3.4 mm; 0.68 mm respectively. The maximum and minimum intermediate and maturity values for EToPan, EToFAO-Penman 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, FAO-Penman, Computation, Crop coefficiente

full text

Optimisation of the Start-up and Operation Regimes of Cooling Water Pumps of a High-Power 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 start-up 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

full text

Implementation of an Automatic System for the Monitoring of Start-up 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 high-power 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

full text

Influence of the Fusing Process on the Wear and Corrosion Properties of NiCrBSi-Coatings

Evelina Roxana Secosan, Gabriela Marginean, Relu-Costel 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 X-ray 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 pin-on-disk 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, self-fluxing 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

full text

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

full text

Anul XXII (2015), Nr. 2




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: Re-development, 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

Sensitivity-based 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

Anca-Andreea 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 Double-Tube Heat Exchanger

Navid Bozorgan

In the present paper, CuO/Ethylene-Glycol (EG) nanofluid with dp=29 nm and volume fractions of nanoparticles ( f = 1-10% ) as coolant has been used in a double-tube 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, Double-tube heat exchanger, thermal conductivity coefficient, Heat transfer performance

full text

Identification of the Opportunities for Future Development of Tidal Energy

Navid Bozorgan, Mohammad-RezaBatevandi, 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

Ana-Maria 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 Burridge-Knopoff Model for Friction

Veturia Chiroiu, Dan Dumitriu

The paper presents an extension of the Burridge-Knopoff (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 sliding-stationary sliding, and correctly reproduces the stability diagram for sliding friction under various loading conditions.

Keywords: friction, Burridge-Knopoff, 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 in-house 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

Vibration-Based 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, non-destructive 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 parameter-based non- destructive tests to assess damages in reinforced concrete beams under static load. Four-point 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, Non-Destructive 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 physico-mechanical 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, Gilbert-Rainer 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: Double-clamped 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 band-gaps 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 band-gap. If the band-gaps are not wide enough, their frequency ranges do not overlap. These band-gaps 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 band-gap, control

full text

New Comparative Study through Modal Analysis of Thin Trapeze Shape Plates Clamped on Contour without and with Damages

Cornel Hatiegan, Marian-Dumitru 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 non-potable applications and exponential world population increase is a strong constrain to Human Development Index and social-economic 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 technically-based 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 water-stress in Ikare. Annual non-revenue 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 non-revenue 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 frequency-specific 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 band-gap, linear defects

full text

On the Evanescent Waves in Sonic Band-gaps

Ligia Munteanu, Rodica Ioan

The band-gaps 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 band-gaps and sustain an evanescent mode. If the waves diverge, a defect can terminate this exponential growth.

Keywords: sonic composite, full band-gap, 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, Edwald-Viktor 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

Marian-Dumitru 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 Rainfall-Rainwater 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 fully-harnessed, 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 far-removed 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

full text

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

full text

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

full text

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 multi-body 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, multi-body, constraints

full text

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

full text

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

full text

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 propagation-learning 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 1.13×10-3. Results show that the obtained formulation is obviously within acceptable limits.

Keywords: NanoFluid, Finite Volume Method, Artificial Neural Networks, Channel, Mixed Convection

full text

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

full text

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

full text

Numerical Investigation of Turbulent Forced Convection Nanofluids Inside an Annulus

Farhad Vahidinia, Mohadeseh Miri, Navid Bozorgan

Turbulent forced convection heat transfer of Al2O3-water 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. Two-dimensional elliptic governing equations were used and the second-order 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

full text

Book review,Optimum Design of Steel Structures, Proiectarea optima a structurilor metalice

full text