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

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


Anul XX (2013), Nr. 1




Dynamic Impact Test of the Railing with Dissipative Elements
Eugen-Marius Afronie , Tiberiu Stefan Manescu, Constantin Vasile Bîtea

By definition, the railing is a wall or a railing of little height witch serves to delimit the edge of a road, a bridge, aimed at stopping vehicles and restoration mainly on carriageway, pedestrians and conveyance of other road users.

Keywords: railing, steel, deformation, protection, safety

full text

Fuzzy Logic Based Speed Control System for Three-Phase Induction Motor
Marwan A. Badran, Mostafa A. Hamood, Waleed F. Faris

Three-phase induction motors have been used in a wide range of industry applications. Using modern technology, the speed of induction motor can be easily controlled by variable frequency drives (VFDs). These drives use high speed power transistors with various switching techniques, mainly PWM schemes. For several decades, conventional control systems were applied to electric drives to control the speed of induction motor. Although conventional controllers showed good results, but they still need tuning to obtain optimum results. The recent proposed control systems use fuzzy logic controller (FLC) to enhance the performance of induction motor drives. In this paper, a fuzzy logic based speed control system is presented. The proposed controller has been designed with MATLAB/SIMULINK software, and it was tested for various operating conditions including load disturbance and sudden change of reference speed. The results showed better performance of the proposed controller compared with the conventional PI controller.

Keywords: Electric Drive, PI controller, Fuzzy Logic Controller

full text

Modeling of Discontinuities in Resistance Structures due to Corrosion
Daniel Bobos

The corrosion process is a process that produces significant negative effects on the resistance structures by reducing their section and by deterioration of mechanical properties of materials. In this paper are presented some notions about the corrosion process, types of corrosion encountered and types of geometric models that can be used for analytical calculation and for numerical simulation using finite element analysis programs, of the effects produced in the corrosion process on the natural frequency of the structure elements.

Keywords: corrosion, geometric model, natural frequencies

full text

The Performance Evaluation of Overall Heat Transfer and Pumping Power of ?-Al2O3/water Nanofluid as Coolant in Automotive Diesel Engine Radiator
Navid Bozorgan, Komalangan Krishnakumar, Nariman Bozorgan

The efficiency of ?-Al2O3/water nanofluid as coolant is investigated in the present study. ?-Al2O3 nanoparticles with diameters of 20 nm dispersed in water with volume concentrations up 2% are selected and their performance in a radiator of Chevrolet Suburban diesel engine under turbulent flow conditions are numerically studied. The performance of an automobile radiator is a function of overall heat transfer coefficient and total heat transfer area. The heat transfer relations between nanofluid and airflow have been investigated to evaluate the overall heat transfer and the pumping power of ?-Al2O3/water nanofluid in the radiator with a given heat exchange capacity. In the present paper, the effects of the automotive speed and Reynolds number of the nanofluid in the different volume concentrations on the radiator performance are also investigated. As an example, the results show that for 2% ?-Al2O3 nanoparticles in water with Renf=6000 in the radiator while the automotive speed is 50 mph, the overall heat transfer coefficient and pumping power are approximately 11.11% and 29.17% more than that of water for given conditions, respectively. These results confirm that ?-Al2O3/water nanofluid offers higher overall heat transfer performance than water and can be reduced the total heat transfer area of the radiator.

Keywords: Automotive Diesel Engine Radiator, Nanofluid, Turbulent Flow, Overall Heat Transfer, Pumping Power

full text

Study of Finite Element Number Influence over the Obtained Results in Finite Element Analyses of a Mechanical Structure
Ana-Maria Budai

This paper present the results of a study that was made to establish the influence of finite element number used to determined the real load of a structure. Actually, the study represent a linear static analyze for a link gear control mechanism of a Kaplan turbine. The all analyze was made for the normal condition of functioning having like final scope to determine de life time duration of mentioned mechanism.

Keywords: linear, static, analyze, link, finite element

full text

Cavitation Erosion Research for AlSi12 Alloy Tested at Different Time Periods
Daniel Chirus, Marian-Dumitru Nedeloni

This paper presents cavitation erosion research for 2 batch of an AlSi12 alloy. The tests were made on a cavitation stand in laboratory, using the stationary specimen method. This alloy is not subject to cavitation, but the experimental research highlight the behavior of AlSi12 alloy when the time periods are different. The research results are presented through graphs and representative images.

Keywords: cavitation erosion, AlSi12 alloy, time periods

full text

Study of Phosphating Process for Artillery Pipes Subjected to Mechanical Self-shrinkage with Mandrel
Ioan Ciorba

This paper present the results of a study that was made to establish the optimal parameters of phosphating process for artillery pipes. The optimal parameters that were determined after analysis are: the temperature of phosphating solution respectively the holding time in the phosphate bathroom to obtain a maximum thickness of phosphate layer.

Keywords: phosphate, artillery, pipes, self-shrinkage, mandrel

full text

Influence of the Rib Radius on the Maximum Stress and Deformations of a Corner Bracket
Vasile Cojocaru

The influence of the radius of circular ribs on the maximum stresses and deformations of a corner bracket was analyzed. The results were obtained using simulations based on finite element method. Two geometries were studied: with one and two ribs. For each of these two geometries the radius of the ribs was ranged between 3 mm and 9 mm. The parts were subjected to bending. The simulations show that the increase of the ribs radius generates a substantial decrease of the maximum stresses and the maximum deformations.

Keywords: rib radius, stresses, deformations, finite element method, corner bracket

full text

The Influence of Hydraulic lay out on the Performances of the Hydraulic Turbine from HPP Raul Alb
Adrian Cuzmos, Nicolae Brebu, Viorel Campian, Ioan Ion, Cosmin Dumbrava

At the commissioning of HPP Raul Alb hydro units it has been found that the hydro units were unable to achieve the guaranteed maximum power. The present work paper presents the results of the tests performed in order to determine the maximum power it can reach these two hydro units in single and parallel operating mode.

Keywords: turbine, hydro unit, power, turbine power, hydraulic lay out

full text

Intex Tests Performed on Hydro Unit no2 from HPP Ruieni before and after Refurbishment
Adrian Cuzmos, Nicolae Brebu, Viorel Campian, Cosmin Dumbrava

The paper work presents the results of index tests performed on HPP Ruieni hydro unit no2 before and after refurbishment, using for discharge measurements the Winter-Kennedy method.

Keywords: Index tests, hydro unit, hydraulic turbine, wicket gates, Winter-Kennedy method

full text

Determine the Correlation between Wicked Gates Angles and Servomotors Strokes for Asymmetric Hydrofoil
Daniel Daia, Dorian Nedelcu

The paper describe the results obtained from theoretical calculus of the kinematics of the wicked gates for the correlation: ao=f(a); aor=ao/Do(a); S=f(a) and propose analytical formulas for ao=f(a) correlation, applicable to 16, 24 wicked gates blade number and asymmetrical hydrofoils; also, numerical results compared with graphical values are presented.

Keywords: Wicked gates, kinematics, asymmetric hydrofoil

full text

Optimal Encoding of Data in Data Transmission Channels
Silviu Draghici, Cornelia Anghel Drugarin, Cristian Chioncel

This paper aims to present the methods of achieving an optimal encoding in the data communication channels. After a short description of the communication channel and of the data communication channel types, follow briefly a few notions of the data channel enthropy, information, transinformation, with their properties, definitions and mathematical relations connecting them. Chapter 2 presents the concept of optimal code, following a detailed description (using two suggestive examples) of the two main methods used to obtain an optimal code: Shannon-Fano and Huffman.

Keywords: optimal code, communication channel, entropy, information, transition functions

full text

Modal Analysis of Thin Plates with Damage Simply Supported on all Edges
Cornel Hatiegan, Gilbert-Rainer Gillich, Nicoleta Gillich, Marius Tufoi, Mihaela Raduca

This paper presents the natural frequencies obtained by modal analysis for five types of rectangular thin plates. These plates are simple supported on all edges, and are without damage, with a lateral damage and with a damage placed in the in center, in both cases two types of damage being used. We compared the results and highlighting the way how natural frequencies changes due to damage.

Keywords: thin plates, natural frequency, vibration, damage

full text

Equation of Motion and Determining the Vibration Mode Shapes of a Rectangular Thin Plate Simply Supported on Contour Using MATLAB
Cornel Hatiegan, Gilbert-Rainer Gillich, Eugen Raduca, Marian-Dumitru Nedeloni, Lenuta Cîndea

This paper presents the differential biharmonic equation of thin plates through which, the vibration mode shapes for a rectangular thin plate simply supported on contour were obtained. Also, the first four vibration mode and the first four natural frequencies of this rectangular thin plate of steel, were obtained. Using MATLAB software, the vibration mode shapes were graphically represented.

Keywords: Equation of motion, vibration mode shapes, MATLAB

full text

Study of Geometric Model Car Body through the Finite Element Mesh
Cornel Iacob-Mare

The paper proposes an analysis of a freight wagon body structure with high walls that has platform to maneuver through study recommended medium for geometric model finite element mesh type Shell63.

Keywords: finite element, meshing, wagon bodz

full text

Effective Stiffness and Period of Friction Bearing Devices with one Concave Sliding Surface for Different Load Conditions
Vasile Iancu Camelia Stefania Jurcau, Gilbert-Rainer Gillich

The friction pendulum system is a passive earthquake device used for a seismic isolation of buildings, bridges and other types of structures; their purpose is to protect, control and limit the energy transfer from the soil to the structure and fully dissipate seismic energy. In the paper we determine the stiffness and effective period of the friction pendulum system with one sliding surface for different levels of horizontal load..

Keywords: earthquake isolation, friction pendulum, structural integrity, stiffness

full text

Contributions to the Structural Analysis of the Double Gear Harmonic Transmission
Draghita Ianici

In this paper, we present the construction and functioning of a new constructive variant of harmonic drive called double gear harmonic transmission (DGHT). In the second part of the paper, we present the desmodromy analysis of the DGHT considering the planar approach of the respective mechanism. At establishing the mobility, class and order of the DGHT we have used the procedure of instantaneous– isokinetic transformation wich followed the identifica-tion of the kinematic groups of the mechanism and the replacement of the higher kinematic pairs by links and by lower kinematic pairs.

Keywords: double gear harmonic transmission, structural analysis, link, kinematic pair

full text

Force Analysis of a Double Gear Harmonic Drive
Sava Ianici

The paper presents an original method for determining by experimental means the tangential forces distribution in the gearing’s zones from the portant elements of the double gear harmonic drive, as well the scheme of the used testing stand. Taking into consideration the results of the theoretical and experimental tests it may be asserted that they concord almost entirely, the deviation being under 6%.

Keywords: double gear harmonic drive, tangential force, experimental analysis, testing stand

full text

Forming Tendency Distribution of Oxide Inclusions in Kaplan Blade Castings
Cinca Ionel Lupinca, Constantin Marta, Relu Costel Ciubotariu, Rodica Radulea, Cornelia Ecaterina Cornean

The results of theoretical and practical studies realized on Kaplan rotor blades, cast from high steels alloyed with chromium and nickel represent the objective of this paper. The data presented refer to the distribution of alloy elements in the entire volume of the casting, resulted from the chemical composition analysis, determined on specimens taken from certain areas of the casting; the forming process and the distribution of oxide inclusions during the mould filling process and during the solidification process. In order to obtain results we have applied the AnyCasting simulation software. Microstructures of specimens from four different areas of the casting are also presented in this paper.

Keywords: Kaplan blade, simulation, martensite

full text

Considerations about how the Numerical Methods are Choose in Purpose to Calculate the Stress – Deformations from Rolling Bearings
Tiberiu Manescu jr.

The paper present the simulations made with finite element method for a simplified model of rolling bearing balls. The simulations were made with Ansys software. The simplified model of the bearing was made from a ball and two parallel planes.

Keywords: rolling bearing, finite element, Ansys, contact, stress

full text

Researches on Wear Evolution of Xylan 1052 Two-Layer Coating under Hard Working Loads or Different Rotational Speeds
Ion-Cornel Mituletu, Ion Vela, Gilbert-Rainer Gillich, Marius Tufoi

Assuming that vibration and noise amplitude depend on coating thickness, here were performed important tests about wear of the Xylan 1052 coating. Applying variable contact stress by different load pressures on a disk coated, and keeping the rotational speed constant, a wear evolutions diagram has resulted. Also, a diagram with the wear evolutions of Xylan 1052 coating has been achieved by using the same load pressure and varying the rotational speed. This information offers significant knowledge about Xylan 1052-film wearing, reflecting an appreciation of the running-in period and the coating thickness. Further on, the proper working time is accomplished, as well as the minimum coating thickness whereas the covering becomes irrelevant to use.

Keywords: wear evolution, Xylan 1052 coating, contact stress, rotational speed, coated disk

full text

Lubrication Influence on Wear Evolution of Xylan 1052 Coated Disk Tested at Various Rotational Speed and High Contact Stress
Ion-Cornel Mituletu, Ion Vela, Zoltan Korka, Marius Tufoi

This paper relates the lubrication influence on the Xylan 1052 coating applied as the surface layer of a testing disk. By pressing a coated and uncoated bearing ball against the surface of coated disk having different rotational speeds, wear evolution diagrams have been achieved. Tests were performed in three specific conditions, when the disk coated surface is: dry, under poor or continuous lubrication. These conditions allow understanding the influence of poor or continuous lubrication on the behavior of coated disk surface at the contact stress. Such conditions could practically occur due to some problems appearing in industrial environment.

Keywords: wear evolution, dry test, poor lubrication, continuous lubrication, Xylan 1052 coated disk

full text

Applications of the Rapid Prototyping Technology to Manufacture the Pelton Runners
Dorian Nedelcu, Raoul Avasiloaie, Danut Florea, Aleksandar Rajic

The paper presents an application of the Rapid Prototyping technology using Objet Desktop 3D Printer to manufacture two Pelton runners that are destined for experimental measurements on a Pelton microturbine. The runners are different by bucket’s number and the bucket’s geometry of the second runner is similar with those of the first runner, but scaled in all directions with the bucket’s numbers ratio.

Keywords: Rapid Prototyping, Pelton, runner

full text

The Reverse Engineering of a Spring Support using the Noomeo Optinum 3D Scanner and the Rapidform XOR3 Software
Dorian Nedelcu, Aleksandar Rajic, Danut Florea, Raoul Avasiloaie

The paper presents an application of the Reverse Engineering technology using a Noomeo Optinum 3D scanner to read the complex shape of the spring support and generate the geometry in a computer file that can be processed by Computer Aided Design software. Rapidform XOR software was used to convert the scanned data into a solid model.

Keywords: Reverse Engineering, 3D Scanner, spring, Rapidform XOR3

full text

Big Data in High Performance Scientific Computing
Florica Novacescu

The main concern of this study is to find the bottlenecks that are caused by the deluge of data, in the supercomputing community. To be more precise, the research targets the big data community, and is concentrated around identifying the new challenges posed by the huge amounts of data resulted from the numerical simulations using supercomputers..

Keywords:supercomputing, big data, high performance scientific computing, big data challenges

full text

The Block Diagram for the Synchronous Motors used for the Compensation of the Reactive Power
Iulius Petrica, Adrian Valentin Petrica

The optimal control system for the compensation of the reactive power in an energetic consumer assembly is presented, containing one or more synchronous motors, connected to the same power bars in parallel, including asynchronous motors and static converters. The compensation of the reactive power absorbed from the system by the consumers is possible, using a optimal control system that controls the reactive power provided on the bars by the synchronous motors on condition that the power losses in the created whole are zero. A limited functional block diagram of the synchronous motor, which is the controlled object completed with the control circuits of the exciting tension and current is obtained having as set value the sum of all reactive currents of the consumers from the power assembly. The optimization is obtained using the module criterion of Kessler.

Keywords: asynchronous motors, reactive power, block diagram, Kessler

full text

Computer Simulation of Water Flowing inside Turbine HYE 10a, a Modern Method for Checking of the Structural Improvements

Florin Pomoja

This paper presents theoretical results of flow simulations, performed on cross-flow type turbine of 8.25 kW, and also the results obtained on the improved turbine, with modified shapes for the rotor, case, and guiding palette.

Keywords: Computational Fluid Dynamics, cross-flow turbine, 8.25 kW

full text

Anul XX (2013), Nr. 2




A Continuous Approach of the Contact Dynamics

Petre P.Teodorescu, Veturia Chiroiu

Ther paper is devoted to the analysis of a sonic composite under dynamic contact with friction loading, by using LISA (local interaction simulation approach). LISA is an an efficient tool for the numerical simulation of the acoustic wave propagation in heterogeneous material specimens, in particular those with sharp boundaries between different materials, like in sonic composites. Boundary conditions are introduced to contain contact interfaces with frictional slips.

Keywords: sonic composite, auxetic foams, contact, friction, LISA

full text

On the Modeling of Contact Interfaces with Frictional Slips

Ligia Munteanu, Cornel Brisan

The paper analyses the contact interfaces between the scatterers and the matrix into the sonic composites, in the presence of the frictional slips. The sonic composite is a sonic liner designed in order to provide suppression of unwanted noise for jet engines, with emphases on the nacelle of turbofan engines for commercial aircraft.

Keywords: sonic composite, contact interface, friction, slip

full text

An Experimental Study of the Cutting Forces in Metal Turning
Zoltan Iosif Korka, Calin-Octavian Miclosina, Vasile Cojocaru

Cutting forces are classified among the most important technological parameters in machining process. Cutting forces are the background for the evaluation of the necessary machining power, as well as for dimensioning of the tools. Cutting forces are also having a major influence on the deformation of the work piece machined, its dimensional accuracy, and machining system stability.

Keywords: Metal cutting, cutting forces, cutting parameters

full text

Some Aspects on Technological Design of a Cam Type Workpiece Using CATIA Software
Calin-Octavian Miclosina, Zoltan Iosif Korka, Vasile Cojocaru, Catalin Lorinti

The paper presents the geometrical models of cam and of semi-finished piece, obtained with CATIA software. Two cam technological routes are shown and the optimal route is chosen. From the technological route, rough milling operation is simulated with CATIA software. By using different milling parameters, various machining time values are obtained.

Keywords: technological design, rough milling, CATIA

full text

Considerations Regarding the Stresses and the Deformations of the Butterfly Valve Body
Florin Peris-Bendu, Adelina Bostan, Viorel Câmpian, Dorian Nedelcu

In the present paper it is analyzed the “von Mises” equivalent stress distribution, respectively strains, which appear in the body of a butterfly valve with nominal diameter (DN) of 2800 mm and operates at a nominal pressure (PN) 19 bar. The paper examines the body of a butterfly valve using finite element method and the followings data is considered to be known: boundary conditions for which the analysis is made in both positions, the valve disk in the closed position and the open position, mechanical characteristics and resistance of the materials for valve body components and loads to which it is subject. The result of the analysis obtained allow optimization of the valve body size by highlighting the oversized areas respectively areas where efforts are maximized.

Keywords: von Mises equivalent stress, strains, body valve, butterfly valve, finite element method

full text

Influence of the Mesh Parameters on Stresses and Strains in FEM Analysis of a Gear Housing
Vasile Cojocaru, Zoltan Iosif Korka, Calin-Octavian Miclosina

The influence of the mesh parameters on the results of FEM simulations depends on the type of the study and the geometry of the system submitted to analyze. In this paper a gear housing was submitted to static analysis. Six studies with distinct values for the maximum dimensions of mesh elements were applied. The results show significant differences for the values of maximum stresses and relatively small differences for the maximum displacements and strains.

Keywords: FEM simulation, mesh, stresses, strains, gear housing

full text

Experimental Determination of Chassis Tensions Freight Wagons with High Walls Tensometriei Resistive Method
Cornel Iacob-Mare, Tiberiu Stefan Manescu

The paper aims at forwarding an experimental analysis, through the method of resistive tensometry, of the strains occurring in the body of a high-walled freight wagon with handler’s platform.

Keywords: wagon body, resistive tensometry, experimental analysis

full text

Comparison Criteria and Performance Levels for Soundproofing Panels Made in Different Constructive Variants
Ana Gheorghe

This paper presents an analysis of the performance lavels and comparison criteria for panels made from different soundproofing materials, in different constructive variants. Setting the performance level, on the basis of normative and regulatory documents, for soundproofing materials contained inside of noise reduction devices, is determined so that it can be defined, tested and established feasible technical solutions for sound absorbing protection, through a dissemination of obtained results as well for ensuring requirements for implementing the technology transfer for manufacturing.

Keywords: soundproofing materials, noise reduction devices, performance levels

full text

An Effective Strategy for Enforcing Ethics Compliance amongst Engineering Industries in the Developing World
Fatai Sado, Faris Waleed

Both governments and professional engineering societies in the developing nations have made several codes of ethics for their engineering industries. But there are little indications that these codes are fully complied with. The consequence of poor compliance has been a tremendous negative effect on humans and the environment. The need to enforce the application of these ethics is therefore necessary. A two way solution is suggested. An internal approach that will require the industries to set up and supervise an ethics compliance program induced by way of government legislation; and an external approach that will require the government to setup an active task force supported with an active involvement of professional societies to setup their own watchdog and ethics compliance scheme for the industries.

Keywords: ethics, engineering industries, compliance

full text

Insertion Loss Analysis of the Acoustic Panels with Composite Construction
Vasile Ovidiu

In order to reduce noise pollution, under European legislation in our country need to align, a special attention has the tests carried out on acoustic panels. The most eloquent attempts, defining traffic noise attenuation are tests that can determine the insertion loss of an acoustic screen. In this paper, it briefly shows the method of determining the insertion loss in octave bands and some real results in the case of acoustic panel in a composite construction.

Keywords: acoustic panels, insertion loss, composite

full text

New Products and Technologies, Based on Calculations Developed Areas
Gheorghe Vertan, Teodor Eugen Man, Eugen Constantin Isbasoiu, Adalbert Kovacs

Following statistics, currently prosperous and have high GDP / capita, only countries that have and fructify intensively large natural resources and/or produce and export products massive based on patented inventions accordingly. Without great natural wealth and the lowest GDP / capita in the EU, Romania will prosper only with such products. Starting from the top experience in the country, some patented, can develop new and competitive technologies and patentable and exportable products, based on exact calculations of developed areas, such as that double shells welded assemblies and plating of ships' propellers and blade pump and hydraulic turbines.

Keywords: invention, developed area, welded assembly, plated blades

full text

Considerations on the Approach of Rolling Contact Fatigue Assuming Multiaxial States of Stress
Tiberiu Manescu Jr, Gilbert-Rainer Gillich, Ion Dumitru, Lorand Kun

Rolling contact fatigue appears in many mechanical elements, in the presence of variable local loadings. During the last years an increasing attention has been awarded macroscopic and mesoscopic analysis of repetitive rolling contact, taking into consideration local triaxial states of stress. Given the above, the authors analyze a fatigue criterion based on the stress state invariants, which is validated using original results as well as existing data from the literature. The criterion is applied to the case of linear contact with friction, which has analytical solutions for the elastic state of stress on the rolling surface and in the adjacent zone. A durability calculation method is presented for the case of rolling contact, based on the ratio between the maximum and experimentally obtained critical (limit) value of a damage parameter.

Keywords: rolling contact, bearing, multiaxial fatigue, stress invariants

full text

Naval Power System Dynamics with Proportional Type Regulators
Eugen-Marius Afronie, Tiberiu Stefan Manescu

The purpose of this paper is to verify through finite element analysis, behaviour of road impact railing. The vehicle used is a hard type, in our case a bus. By definition, the railing is a wall or a railing of little height witch serves to delimit the edge of a road, a bridge, aimed at stopping vehicles and restoration mainly on carriageway, pedestrians and conveyance of other road users.

Keywords: safety, railing, protection, steel, deformation

full text

Climate Changes and their Influence on the Design of Hydraulic Structures from Romania
Florin Trofin

During the last decades, the human being influenced environmentally the Earth, causing global environmental changes of such a size that have become global phenomena.These changes include the climate, ozone layer depletion, biogeochemical cycles, hydrological cycle, and water resources, raising the ocean levels or thermohaline circulation. The hydrological cycle and water resources changes have significant effects on the design of hydraulic structures, provided they are exploited in the presence or absence of major climatic factors, such as water, air, or soil.

Keywords: hydrological cycle, water resources, theoretical probability curve

full text

Examination of Cyclic Plasticity Models Under Uniaxial Loading by Finite Elements Method
Hossein Jarrahzadeh, Shahram Shahrooi

One of the main characteristics of the existing plasticity theories is the lack of a theory and specific equations for them. There are various methods with different results for solution of a plasticity problem. In this paper, two cyclic plasticity models of non-linear (Chaboche) and multilinear (Bessel) kinematic hardening are evaluated based on experimental data for 1% Cr-Mo-V steel alloy. Uniaxial loading on the specimen in seven steps is done by control stress method and using Ansys software. In each step, strains of elastic, plastic and then total have been calculated. The values obtained from simulation compared to experimental results is shown a good agreement on the both results, particularly in non-linear solution.

Keywords: Plasticity Models, Cyclic Kinematics, Plastic Strain, Finite Element Method

full text

Potential of Biogas Power Plant Produced by Anaerobic Digestion of Biodegradable Materials
Nur Shuhada Ghazali, Md Azree Othuman Mydin, Nik Fuaad Nik Abllah

Biogas typically refers to a gas produced by the breakdown of organic matter in the absence of oxygen. It is a renewable energy source, like solar and wind energy. Furthermore, biogas can be produced from regionally available raw materials and recycled waste and is environmentally friendly and CO2 neutral. Biogas is produced by the anaerobic digestion or fermentation of biodegradable materials such as manure, sewage, municipal waste, green waste, plant material, and crops. Biogas comprises primarily methane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulphide (H2S), moisture and siloxanes. The gases methane, hydrogen, and carbon monoxide (CO) can be combusted or oxidized with oxygen. This energy release allows biogas to be used as a fuel. Biogas can be compressed, much like natural gas, and used to power motor vehicles. Biogas is a renewable fuel so it qualifies for renewable energy subsidies in some parts of the world. Biogas can also be cleaned and upgraded to natural gas standards when it becomes bio methane. This paper will discuss the potential of biogas in order to provide a clean, easily controlled source of renewable energy from organic waste materials for a small labour input, replacing firewood or fossil fuels which are becoming more expensive as supply falls behind demand.

Keywords: biogas, anaerobic digestion, waste management, anaerobic digestion, sewage, municipal waste

full text

Effect of Nanofluids on Heat Pipe Thermal Performance: A Review of the Recent Literature
Navid Bozorgan, Nariman Bozorgan

The addition of the nanoparticles to the base fluid is one of the significant issues to enhance the heat transfer of heat pipes. The purpose of this review is to summarize the research done on heat pipes using nanofluids as working fluids in recent years (2012 to 2013). The peer reviewed papers published in citation index journals have been selected for review in this paper. This review article provides additional information for the design of heat pipes with optimum conditions regarding the heat transfer characteristics of nanofluids in heat pipes. Moreover, this paper identifies several important issues that should be considered further in future works.

Keywords: Heat pipes, Nanofluids, Thermal resistance, Heat transfer

full text

Railways Factory in Resita
Cornel Iacob-Mare

This paper proposes an exemption Analysis railway factory in Resita impressed having experience and also provide some technical characteristics of freight wagons representative technology, used to transport products made in factories in ResiNa.

Keywords: railways factory, rail technology, transport, steel industries

full text

Evaluation of the Moldboard Structure Resistance of the Grader Equipment
Carmen Debeleac

In this paper, the author presents a method for evaluation of the moldboard structure resistance of the motor-graders. Usual grader model was chosen to be analyzed by the FEM. Horizontal force of the blade was estimated using the classical soil mechanics theories for cutting soil proposed by McKyes. The simulation results can be useful for structural performance evaluation of these machine used in construction and agricultural fields.

Keywords: grader, moldboard, analysis, FEM

full text

Opnet Analyze for FTP and Video Networktraffic using IP over MPLS Protocol
Ioan Fitigau, Gavril Toderean

MPLS provide an efficient forwarding mechanism, scalability with an important role in switching and routing of packets through the next step in networking evolution, in order to meet the most complex service demands for these users. In this paper we analyze the performance impact of FTP and Video traffic for mpls network and conventional IP network, using Opnet Modeller for simulations. The simulation results are analyzed, showing that MPLS based solution provide a better performance for the traffic over the network.

Keywords: MPLS, IP, Opnet, FTP, Video

full text

The Analysis Regarding the Building of a Hydraulic Power Plant on the Black Sea Shore
Gheorghe Samoilescu, Sergiu Nicolae, Florentiu Deliu, Raluca Apostol – Mates

The present paper represents the result of a research project regarding the construction of a wave driven hydraulic plant that is going to be installed on the Black Sea shore in the area of the city of Constanta. Several phases were analyzed: numerical simulations for the micro plant – wave energy theory; finite element simulation – results and conclusions; generating the blueprint for the construction of the plant.

Keywords: hydro-pneumatic installation, micro-power station, floor coverings, profiles, resistance module

full text

Dependence of the maximum power and wind speed
Florentiu Deliu, Gheorghe Samoilescu, Paul Burlacu

The issue paper is to present renewable energy sources insisting mainly on wind energy. This source is analyzed in the context of Romania in particular and the EU in general. A turbine with horizontal axis is usually coupled with vessel power systems. Wind energy knows an increased growth rate. At the end of the paper are presented possible structure of coupled a wind to power systems.

Keywords: renewable energy, wind energy, wind turbine, vessel energy system

full text

The Possibility of Functioning at Maximum Power for Solar Photovoltaic - Electric Battery Systems
Cristian P. Chioncel, Marius Babescu, Petru Chioncel

The paper presents the functioning of a solar photovoltaic module (PVM) that debits direct to on electric battery (EB). By a good adapting of PVM to EB, so that the no load voltage of the two components (PVM and EB) are well suited, during a day the energy value can be reached near to the maximum possible value, when the PVM functions in the maximum power point (MPP). The proposed solution is much more economic than the classical: PVM + DC – DC + EB because the direct current - direct current power converter, is not necessary (DC - DC).

Keywords: solar photovoltaic module, maximum power point

full text

The Possibility of Functioning at Maximum Power for Solar Photovoltaic - Electric Battery Systems
Cristian P. Chioncel, Marius Babescu, Petru Chioncel

The paper presents the functioning of a solar photovoltaic module (PVM) that debits direct to on electric battery (EB). By a good adapting of PVM to EB, so that the no load voltage of the two components (PVM and EB) are well suited, during a day the energy value can be reached near to the maximum possible value, when the PVM functions in the maximum power point (MPP). The proposed solution is much more economic than the classical: PVM + DC – DC + EB because the direct current - direct current power converter, is not necessary (DC - DC).

Keywords: solar photovoltaic module, maximum power point

full text

Solution for Improve the Efficiency of Solar Photovoltaic Installation
Petru Chioncel, Cristian Paul Chioncel, Nicoleta Gillich

This paper present a solution for improving efficiency of solar photovoltaic installation, realized with fixed solar photovoltaic modules, placed in solar parks or individual installations. The proposed solution to increase the radiation on the solar photovoltaic panels is to use some thin plates covered with a reflective blanket, mounted in front of the solar photovoltaic modules, with the possibility of their adjustment.

Keywords: solar radiation, photovoltaic module, improving efficiency

full text

Modulated Field Synchronous Generator for Wind Turbines
Petru Chioncel, Cristian Paul Chioncel

This paper presents a modern electromechanical conversion system solution as the modulated field synchronous generator, offering on the one hand, an output voltage with constant frequency in terms of speed variation of the wind turbine and on the other hand an advantage power / weight ratio due to the high frequency for which the magnetic circuit of the electric machine is sized. The mathematical model of the modulated field synchronous generator is implemented in MatLAB modeling language, highlighting the command structure on the transistors bases of the inverter transistors, through which the functioning of the electric machine can be studied, especially in terms of the frequency of the delivered voltage.

Keywords: modulated field synchronous generator, inverter, mathematic model

full text

Influence of Urban Traffic Driving Conditions and Vehicle Cubic Capacity on CO and VOC Emissions
Arina Negoitescu, Adriana Tokar

The reports regarding the global warming warn on the urgent need to reduce pollutant emissions and in particular greenhouse emissions. The performed analysis shows that cars equipped with engines operating on petrol, lead to a lower level of pollution, from the point of view of CO (carbon monoxide) and VOCs (volatile organic compounds) emissions at speeds above 50km/ h. Since driving in urban traffic mode involves driving with a speed up to 50km/h, it was comparatively analyzed the automobile engines operation with different cubic capacities. In conclusion, in terms of the analyzed emissions in accordance with the emission standards requirements for urban driving situations, it results that the accepted values of these emissions are recorded for automobile engines of low cubic capacities (under 1.4 l).

Keywords: urban traffic, pollutant emissions, passenger car, cubic capacity

full text

The Influence of the Water Supply Indoor Installations Pipes Wear and Clogging on Water Consumption and Hygiene and Sanitary Comfort Level
Adriana Tokar, Arina Negoitescu

To ensure and increase the hygiene and sanitary comfort degree in buildings older than 25 years, rehabilitation and modernization of water supply indoor installations is required. The rate at which these capital repairs were made to the common facilities is very low, which explains the increasing number of commercial buildings that claims flooded basements due to rusty, clogged or broken pipes. In this regard, the paper analyzes the situation of an apartment building, located in Timisoara, which is 48 years old and to which were made only partial rehabilitation works. The solutions resulted from the performed analysis lead to the necessity of performing the rehabilitation and modernization works by replacing the installation distribution and columns that shows a high wear and clogging degree.

Keywords: hygiene and sanitary comfort, flow, pressure, clogging, rehabilitation

full text

Some Theoretical Observations Concerning the Reverberation Time for the Case of a Harmonic Emitting Source
Dusan Popov, Nicolina Pop, Cornel Hatiegan

In the paper, the reverberation phenomenon produced by the harmonic emission of a sound source is theoretically examined, taking into consideration the absorption of the sound in the air. We obtain a formula which contains, as particular cases, the similar formulae presented in the literature.

Keywords: reverberation time; absorption of sound; acoustic energy

full text

The Evaluation of the Functional Performances for Microhydroaggregates Endowed with Asynchronous Generators by Vibrations Measurements
Valentin Nedelea, Ladislau Augustinov

By this study we aim to establish some methodologies for the estimation of performances for microhydroaggregates by limiting the power according to the vibrations level.

Keywords: asynchronous generator, vibration, turbine, active power, reactive power

full text

The Synchronous Generators Rated Speed’s Influence on Electromagnetic Stresses and on Costs
Elisabeta Spunei, Laurentiu Padeanu, Florina Piroi, ion Piroi, Gheorghe Liuba

During the design of synchronous generators is very important to establish the values of their electromagnetic stresses. The specific literature recommends that these stress values are to be chosen from the curves obtained during experimental design, where the independent values are the polar pitch and the number of pole pairs. The authors of this work propose a method of finding the dependency between the electromagnetic stress and the synchronous generator rated speed to rapidly estimate the stresses in a given interval of rated speed values.

Keywords: synchronous generator, rated speed, electromagnetic stresses, optimal designing, total cost

full text

Research on the Command of a Single-Phase Frequency Converter at High Frequencies
Ioan Ruja, Constantin Marta, Florin Breaban

The present paper forwards several results obtained during the study of the induction heating installations of metallic materials at high frequencies [1]. It details aspects related to the command of a monophase (half-bridge) inverter with PWM signals (Pulse-With-Modulation). The command of the MOS transistors is done with frequencies ranging between [0¸400] KHz and modulation factor variable within the [0-1] range. The possibility to modify the command frequency of the inverter, as well as the possibility to modify the PWM signal modulation factor allows the user to establish various resonance frequencies for the LC (parallel) circuit which, together with the metallic sample, constitutes the inverter charge.

Keywords: heating, melting metallic, signal, induction, resonance

full text

Development and Evaluation of a 2KVA Inverter
Ajayi Adedayo, Olotu Yahaya, D.K Jerome

A 2KV inverter was designed, developed and tested for household applications. It consists of a heavy duty (24 V, 80 AH), oscillator unit, PWM (Pulse-width modulation) controller unit, driver unit, amplifier unit, center-tap step up transformer and battery charger unit. The battery powered the circuitry and the oscillator section generates the drive signal that is amplified and set up the transformer to produce 240 V supply at the secondary winding connected to the output socket of inverter. The feedback control circuit uses discrete components such as: full wave rectifier, pulse width modulator (IC), diodes and other components to sense the output voltage (or load current). When the feedback senses that the load on the inverter output has increased, the inverter control circuitry acts by increasing the width of the switching pulse in the oscillator section which turn on the MOSFETS. MOSFETS turns on for longer time each cycle, automatically correcting the R.M.S value of the output to compensate for any drop in peak-peak output voltage as well as continuous charging of battery, consequently, maintaining a steady output voltage level in inverter irrespective of the load characteristics. The outputs of the tests carried on the unit shows that that instrument performs satisfactory well.

Keywords: Inverter, transformer, voltage, control circuit, current, output, MOSFETS, PWM

full text

Development and Performance Evaluation of a Ceramic Filter for Point-of-Use Water Purification
Bukola Olalekan Bolaji, Olugbenga Oluseyi Akande

In this work, a ceramic filter for point-of-use water purification was designed, fabricated and tested to evaluate its performance in filtering water to the World Health Organisation (WHO) standards. The results of pH of water samples obtained after filtration ranged from 7.68 to 8.11. The range of values obtained after filtration for turbidity, hardness, conductivity, total dissolved solid (TDS) and total suspended solid (TSS) from water samples were 0.07 to 0.55 NTU, 6.0 to 34 mg/L, (1.5 to 3.3) x 10-3S/m, 4 to 25 mg/L and 0.04 to 0.11 mg/L, respectively, while the filter average removal efficiencies of these parameters were 93.1, 85.1, 91.6, 92.3 and 91.4%, respectively. Comparison of the results with the WHO standards for drinking water showed that the ceramic water filter can provide potable drinking water of required standards.

Keywords: ceramic, drinking water, filter, performance, standards

full text

Anul XX (2013), Nr. 3




Theoretical Assessments on Dynamics of Helical Flexible Coupling within Vibratory Equipments

Silviu Nastac, Cristian Simionescu

This study deals with vibratory equipments dynamic behaviour and especially reveals some critical aspects regarding the flexible coupling within and those influences on entire system evolution. Changing of dynamic characteristics, additional dynamic loadings and variances reducing of vibration parameters frame the main hypothesis of the research. This paper briefly presents a few theoretical assessments in terms of linear and nonlinear approaches of driving chain elements. Realistic expanded, also computational simplified models have been provided. Simulated behaviors denote that many of the reported observation regarding the serviceable dynamic distortions are correctly, and impose a set of additional instrumental tests in order to obtain a good accuracy for mathematical models.

Keywords: vibratory equipment, computational dynamics, helical flexible coupling, functional optimization> full text

Basic Approaches of Complex Interaction Drum- Terrain for Vibratory Compaction

Gigel Florin Capatana

In this paper the author tries to use a new method to evaluate and analyze the interaction between roller and terrain. The analysis is rheological approached, with a predominantly dynamic behaviour, so as to reveal the compatibility of the working body performances with the characteristics of the terrain. The basic idea shows that it must be assured the energy transfer maximization in the interaction between the two components of the system. The model must have permanent and continuous adjustments of the material characteristics so it can be evaluated the technological capability. The fulfilling of these objectives will be provided by using a complex model with both distributed and concentrated elements which can have rheology of elastic, dissipative and plastic types. The first conclusions of the presented study goes to the idea that the harmonization of the basic parameters of the model with the experimental values can lead to structural and functional optimizations of the entire technological system.

Keywords: dynamic behavior, rheological evaluation, energy transfer maximization

full text

Particular Approaches about Symmetrical Structures Dynamics
Aurora Potirniche

The paper presents some aspects about dynamic behaviour of a rigid structure building insulated on anti-seismic elastic devices. The structure presents symmetries in terms of the geometrical and insulation configurations, and this allows decoupling of the eigenmodes. Thereby, is simpler to evaluate the impact of the dynamic forces transmitted through the terrain-structure path during the earthquake. Based on the vibration isolation theory, it can be evaluated the isolation degree for the considered structure. It has considered as an excitation factor the complex signal of an earthquake defined through the ground motion acceleration. The analysis that was made in the paper reveals the need to identification and evaluation requirements for the functional correlations between the reference parameters of the considered structure and the characteristics of the isolating and insulating devices.

Keywords: anti-seismic elastic devices, dynamic behaviour, vibration isolation theory, isolation degree, eigenmodes

full text

Issues Regarding the Mechanical Behavior of the Romanesque Roof Structure - Lutheran Church of Sebes
Petrica-Horatiu Suatean

In Transylvania only a few historical roof structures with romanesque character are still preserved, most of them with several structural degradations. The comprehension of mechanical behaviour of these structures makes it easy the work of monuments specialist in terms of diagnosis and structural prediction. In this paper is analyzed the roof structure placed over the main nave of Lutheran Church of Sebes (Alba county- Romania), pursuing the influence of his constitutive elements regarding the structural stability at dead loads and non-gravity loads.

Keywords: historic monuments, historic roof structure, roof structures with a romanesque character, mechanical behavior> full text

The Influence of Porosity and Bioclastic Contents on Limestones Decay
Nicoleta Cobirzan, Anca-Andreea Balog

Industrial fields that assume series production of various assembly parts tend more and more to apply as manufacturing method cold stamping and moulding. At current level of development, this process-ing method compared to others comes with important advantages. Pre-sent paper describes methods applied in active boards manufacturing technology of moulds and stamps.

Keywords: decay, limestone, water absorption, bioclastic, porosity

full text

Determination and Verification of the main Dynamic Characteristics of a Spatially Large Structure Using the Basic Records Combination Method
Patricia Murzea

The aim of the paper is to present some methodological aspects regarding the determination of the vibration eigenmodes of a spatially large, symmetric structure and afterwards to show the obtained results for a spectral analysis of the ground motion in the horizontal plane, corresponding to steady state micro-tremors. The recorded velocigrams concern the rigid body motion of the main ring of the structure (translation along different horizontal directions and rotation with respect to the vertical symmetry axis) as well as ovalization oscillations (mainly second order ovalization). The necessary data for the analysis was obtained through an efficient technique of combining basic records gathered with the help of data acquisition systems, on site, using three different schemes for the placement of the recording sensors..

Keywords: velocigrams, spectral analysis, oscillation ovalizations> full text

Various Forms of Project Delay in the Construction Industry
Nurbasirah Mohamed Alias, Md Azree Othuman Mydin

Project delay can be defined as an incident that causes extended time in order to complete all or part of a particular project successfully. In other words, delay is the time overrun, either ahead of the date for project completion specified by the contract or further than the extensive contract period where an addition of time has been granted. It should be pointed out that the project delay in the construction industry is a universal or large-scale observable fact affecting not only the construction industry but the overall economy of countries too. As far as world construction industry is concerned, project delays are common problems in the construction industries; particularly most common is in the housing development industries. This paper will present different types of project delay that took place around the world. Project delay involves diverse complicated issues all of which are continuously of crucial importance to the parties to the construction contract. These issues concern right to convalesce costs of the project delay or the need to lengthen the project with the considerable right to recovery costs for adjustments to the contract schedules.

Keywords: project delay, construction, contractor, time overrun, completion of project, excusable delay, concurrent delay

full text

Distinctive Structural and Non-Structural Building Defects and Failures in Educational Buildings
Tan Sin Wen, Md Azree Othuman Mydin

Although the maintenance-free building may be a theoretical possibility, all buildings are subject to the vagaries of defects, failures, deterioration and variation. The examples of these problems are fungus growth, peeling paint, termite attack, dampness, defective rainwater goods, roof defects, harmful growth, settlement, foundation failure, roof collapse and others. There are a great number of building defects and failures arose and being reported officially by mass media, especially problems with educational buildings. Theoretically, all buildings tend to deteriorate over period of time due to aging or other factors, regardless the types of buildings. There are several main factors can be taken into account such as design fault, poor maintenance, poor workmanship, building age and location of building. This paper will discuss on distinctive structural and non-structural building defects and failures than frequently happened in educational buildings. This paper is noteworthy to render varies of problems generally faced by Malaysian educational buildings to the public. As such, the awareness among them can be raised or improved. Furthermore, the public will concern, especially the government authorities should emphasize the laws and regulations to enforce the safety of construction work as well as the procedure in giving approval to the occupation of educational buildings.

Keywords: educational building, building defects, failures, common defects, maintenance, termite attack, settlement

full text

Potential Implementation of Green Prefab System in Malaysian Construction Industry
Md Azree Othuman Mydin

Prefab system can be defined as a building process in which sections of modules of the structure are assembled at a remote location, and then transported to the construction site. This type of construction technique is very lucrative and often makes it possible to complete a building project in as much as half the time required for more traditional methods. Prefab construction is frequently employed with the construction of new houses; the strategy can also be used with other buildings. The outstanding ability behind prefab construction is based on the idea that by using standard components that are partly assembled on a manufacturing floor, there is less time involved in the actual construction process. The modules are transported to the site, using freight transportation. At the site, the modules are unloaded, moved into position with the aid of heavy machinery, and connected to form a single building. Along with the fast assembly, prefab construction could often save a great deal of money on the building construction. By using standard patterns, the building materials are pre-cut at the manufacturing site. This eliminates an enormous deal of the waste in timber and other components that can crop up during the process of building. Consequently, a prefabricated house with three bedrooms is likely to cost significantly less than a three bedroom dwelling that is constructed from scratch at the building site. This paper will discuss the potential of green prefab construction in Malaysia.

Keywords: prefabrication, green technology, standard components, precast, traditional construction, modular system

full text

Essential Approach of Maintenance Management System of Office Building
Masyatul Husna Othman, Md Azree Othuman Mydin

Buildings will be worn-out, dilapidated and dirty as time goes by; but with good maintenance management we can at least prolong the lifespan of building longer as well as provide the building services and keep the building performance at it ultimate level. The importance of carrying out a systematic and routine maintenance works as part of works to conserve building performance is often neglected due to various factors including due to misunderstanding on the needs of the maintenance works itself and budget allocated. Thus, the purpose of the present study was to evaluating the level of maintenance management and quality of services in office buildings. This study also sought to answer the following question to determine the basic approach of maintenance management system used for office buildings..

Keywords: building maintenance, office building, maintenance management, building performance, facility management

full text

Investigation on Prefabricated Building System Skilled Component Installers
Nurul Rezuana Buyung, Md Azree Othuman Mydin, Abdul Naser Abdul Ghani

In the face of an increasingly challenging era of globalization, skills and new equipments which includes prefabricated building components, known as Industrialized Building System (IBS) has been introduced towards achievement of sustainable construction. IBS is a construction system in which the components are manufactured in a factory, on or off site, positioned and assembled into complete structures with minimal additional site work. IBS requires high construction precision and needs a higher skill level of workers. Compared to the conventional construction method, the skill level of IBS workers is more demanding. Although there are a lot benefits in implementing IBS, the construction industry still not rapidly implementing IBS. The IBS method still considered new and even though there are a lot of benefits it still faces barriers. In an IBS construction, the role of the contractor is shifted from a builder to an assembler on the site. Therefore, this requires the contractor to be prepared technologically with IBS knowledge and skills. It is generally perceived that the number of skilled IBS installers in Malaysia is still low even though the system has been implemented for a long time. This research is carried out to find out whether the existing number of IBS installer is sufficient. Primary data was collected by carrying out interviews with the contractors at the IBS construction site in Penang Island in order to get the contractor’s feedback regarding this issue. Meanwhile, the secondary data was collected from government agencies to get the number of existing IBS installer and the number of IBS projects done in government projects. The results from this study indicated that not all categories of skill workers are in shortage. However, the number of precast concrete installer is in a critical shortage.

Keywords: prefabricated, industrialized building system, building component, contractor, skilled worker, installer

full text

Engineering Performance of High Strength Concrete Containing Steel Fibre Reinforcement
Md Azree Othuman Mydin

The development and utilization of the high strength concrete in the construction industry have been increasing rapidly. Fiber reinforced concrete is introduced to overcome the weakness of the conventional concrete because concrete normally can crack under a low tensile force and it is known to be brittle. Steel fibre is proved to be the popular and best combination in the high strength concrete to result the best in the mechanical and durability properties of high strength concrete with consideration of curing time, steel fibre geometry, concrete grade and else more. The incorporation of steel fibre in the mortar mixture is known as steel fibre reinforced concrete have the potential to produce improvement in the workability, strength, ductility and the deformation of high strength concrete. Besides that, steel fibre also increases the tensile strength of concrete and improves the mechanical properties of the steel fibre reinforced concrete. The range for any high strength concrete is between 60MPa-100MPa. Steel fibre reinforced concrete which contains straight fibres has poorer physical properties than that containing hooked end stainless steel fibre due to the length and the hooked steel fibre provide a better effective aspects ratio. Normally, steel fibre tensile strength is in the range of 1100MPa-1700MPa. Addition of less steel fibre volumes in the range of 0.5% to 1.0% can produce better increase in the flexural fatigue strength. The strength can be increased with addition of steel fibre up to certain percentage. This paper will review and present some basic properties of steel fibre reinforced concrete such as mechanical, workability and durability properties.

Keywords: high strength concrete, steel fibre, mechanical properties, compressive strength, durability, tensile

full text

Investigation on Adaptive Re-use of Heritage Building in George Town, Penang
Marhamah Abdul Hadi, Md Azree Othuman Mydin, Noor Faisal Abas

Adaptive re-use of heritage buildings in George Town has gained attention from their owners. Their owners either private owners or government, want to adapt their respective buildings to new usage for instance to become a gallery, museum, restaurant, boutique hotel and many more. Every heritage building that is being adapted to paper main objective is to identify the changes made in terms of structure, space and material when adapting the heritage buildings to a new usage specifically into a gallery. Two heritage buildings are chosen as case studies for this paper which are Rumah Teh Bunga and Fort Cornwallis; both buildings located in Penang, Malaysia. The changes made to these two buildings were analyzed using the guidelines provided which are Guideline for Conservation areas and Heritage Buildings and National Heritage Acts 2005. Both buildings will be analyzed using National Heritage Acts, while only Fort Cornwallis will be analyzed using Guideline for Conservation areas and Heritage Buildings. Adaptation of these two heritage buildings requires changes in structure, space and material. The changes in Rumah Teh Bunga focuses more on materials and space while changes in Fort Cornwallis emphasize more to space and addition of other structures. Analysis on the changes are made by using the guideline provided, most of the changes made to both of these heritage buildings comply the rules and regulations stated in the guideline. It was found from the data that some of the reasons on why the owner change Rumah Teh Bunga to gallery are because of its complicated procedure that involves in privatization of this building to other owner and the need to promote the heritage significance of this building to the public. As for Fort Cornwallis, the adaptation is more on strengthening its value as a fort and becoming a tourist attraction.

Keywords: daptive re-use, heritage, Penang, gallery, conservation building, adaption, George Town> full text

Critical Causes and Consequences of Construction Project Interruption: Client, Contractor, Consultant and External Factors Standpoints
Nurbasirah Mohamed Alias, Md Azree Othuman Mydin

It should be pointed out that the dilemma of interruption and stoppage in the construction industry is a large-scale trend. Construction interruption and stoppage is considered one of the most recurring problems in the construction industry. Construction Interruption and stoppage is always measured as costly to all parties concerned in the projects and very often it will result in clash, claims, total desertion and much difficult for the feasibility and it slows the growth of construction sector. The objective of the research work that underpins this paper was to investigate the Factors and Consequences of construction projects on local contractors. A construction project is commonly acknowledged as successful when the aim of the project is achieved in terms of predetermined objectives that are mainly completed the project on time, within budget and specified quality in accordance with the specifications and to stakeholders’ satisfaction. One of the most important problems that may arise in the construction project is delays and the magnitude of these delays varies considerably from project to project. According to delay categories that were contractor related, client related, consultant related, labour related and external related, the study revealed the six major effects of delay that were time overrun, cost overrun, dispute, arbitration, total abandonment, and litigation.

Keywords: construction, project management, interruption, delay, contractor, cost, time, claims

full text

On Damage Detection in Beams based on Dynamic Tests and Transitory Analysis
Silviu Nastac

This study is covered by Structural Health Monitoring Concept - SHMC, and deals with some basic problems regarding the diagnosis of the current health status during exploitation. The detection of a potential area of structural damage supposes a great volume of bulky investigations performed on each structure element. Dynamic tests can provide a relative simple method to obtain some relevant information regarding both qualitative and quantitative levels of structural capability in order to maintain the initial performances during its regular working regime. In this paper is shown the influences of a certain crack which is developed in a simple beam upon the dynamic characteristic. The essential information about the linkage between the crack parameters and the dynamic evolution is also presented. A main concluding remark reveals a good correlation of the damage characteristics with the dynamic capability performances, supplying an appropriate way to estimate the structural health level based on a regular set of dynamic instrumental investigations.

Keywords: health monitoring, dynamic instrumental tests, structural damage detection, transfer function, transitory analysis

full text

Reliability Study Regarding the Use of Histogram Similarity Methods for Damage Detection
Nicoleta Gillich, Andrea Amalia Minda, Zeno-Iosif Praisach, Carla Protocsil, Peter Lorenz, Gilbert-Rainer Gillich

The paper analyses the reliability of three dissimilarity estimators to compare histograms, as support for a frequency-based damage detection method, able to identify structural changes in beam-like structures. First a brief presentation of the own developed damage detection method is made, with focus on damage localization. It consists actually in comparing a histogram derived from measurement results, with a large series of histograms, namely the damage location indexes for all locations along the beam, obtained by calculus. We tested some dissimilarity estimators like the Minkowski-form Distances, the Kullback-Leibler Divergence and the Histogram Intersection and found the Minkowski Distance as the method providing best results. It was tested for numerous locations, using real measurement results and with results artificially debased by noise, proving its reliability.

Keywords: beam, frequency, damage detection, histogram, Minkowski Distance, Kullback-Leibler Divergence, Histogram Intersection

full text

On the Robustness of the Minkowski Distance for Histogram Dissimilarity Evaluation with Focus on Damage Location in Beam-Like Structural Elements
Petru-Florin Minda, Nicoleta Gillich, Peter Lorenz, Gilbert-Rainer Gillich, Florian Muntean

This paper analyses the robustness of a histogram dissimilarity estimator, namely the Minkowski Distance, and its sensitivity to input/ measurement errors. As a result of prior researches we developed a method to detect, locate and assess damages in beams, based on frequency shifts. The localization process consists in fact in comparing a histogram derived from vibration measurements, with numerous histograms representing the damage signature for all possible locations along the beam. We tested the stability of Minkowski Distance L2, for frequencies measured on real beams; other tests were made for results artificially debased by noise. In all cases this metrics proved its robustness and reliability.

Keywords: beam, frequency, damage detection, histogram, Minkowski Distance> full text

The Influence of the Number of Finite Elements upon the Accuracy of the Results Obtained Using Discrete Models
Vasile Iancu, Carla Protocsil, Nicoleta Gillich, Cornel Hatiegan, Gilbert-Rainer Gillich

Discrete models are often used because they require a simple mathematical approach, even if their accuracy is inferior to continues models. This paper presents a study regarding the influence of the number of used elements upon the accuracy with which the natural frequencies of straight beams can determined. The results show that, to achieve a reasonable accuracy, it is necessary to use at least ten elements, while for rigorous calculus, more than three hundred elements must be considered.

Keywords: beam, frequency, discrete model, model accuracy

full text

Experimental Research of the Behavior of a Bus Structure in Case of Rollover
Marian Tiganasu, Petru Dumitrache

The article highlights the main aspects to be considered in the experimental research on behavior of a bus structure in case of rollover. In this context, are presented the experimental procedure, the experimental objectives, the imposed measurements and the obtained results. In the final part of the article are presented some observations and conclusions of the authors.

Keywords: Experimental research, structure behavior, bus rollover

full text

About the Study of the Bus Structure Behavior in Case of Rollover, Using Numerical Simulation
Marian Tiganasu, Tiberiu Manescu, Petru Dumitrache

The objective of this paper is the highlighting of the main aspects that be considered in study of the bus structure behavior in case of rollover, using numerical simulation of this real situation. In first part of the paper are presented, briefly, the general framework and the reference documents governing the mechanical protection of the passengers in case of the bus rollover. Next, the main parameters defining the numerical simulation of rollover bus are analyzed. Also is analyzed the influence of these parameters on the accuracy of the numerical results obtained by simulation. In this context, are given the necessary information to correctly modeling the reality so that the results to have an imposed accuracy.

Keywords: Bus structure behavior, bus roll-over, numerical simulation

full text

Experimental Research on the Influence of Vibration on Fingers Mobility
Radu Panaitescu-Liess

In many industrial activities the human body is exposed to vibrations transmitted through the hand-arm system. A long exposure to these vibrations can cause various health problems of blood vessels, nerves, muscles, bones, joints and upper limb [1]. This paper presents some considerations about the influence of vibration on finger joints mobility. I used a MediTouch system which consists of a motion capture device (an ergonomic glove) and a dedicated software.

Keywords: MediTouch, ergonomic glove, finger, joints, mobility

full text

Frequency Changes in Thin Rectangular Plates due to Geometrical Discontinuities. Part I: Finite Element Analysis
Tufoi Marius, Hatiegan Cornel, Gilbert-Rainer Gillich, Carla Protocsil, Ionica Negru

This paper series presents an analysis regarding the dynamics of thin rectangular plates, embedded on all edges, in order to highlight the effect of geometrical discontinuities upon the natural frequencies. In this paper the first thirty natural frequencies were obtained for a plate without defect and the same plate with six different types of defect. The defect was placed in the centre of the plate; one dimension (the width) was increased successively. The results in terms of frequencies and mode shapes are finally presented.

Keywords: defect, finite element analysis, plate, natural frequency, vibration mode shapes> full text

Frequency Changes in Thin Rectangular Plates due to Geometrical Discontinuities. Part II: Frequency Shift Interpretation
Tufoi Marius, Hatiegan Cornel, Gilbert-Rainer Gillich, Ovidiu Vasile

This paper, as part of a series dedicated to highlight the way how natural frequencies of plates change due to damage, presents results of numerical and experimental modal analysis made on thin rectangular plates clamped at all four lateral surfaces. These results where processed and the so-called relative frequency shift for thirty vibration modes determined. It was revealed the rules how the frequencies change by varying the damage geometry, and proved that these data can be used for damage identification. Finally, the results are compared with measurements, in order to demonstrate the validity of the theoretical considerations.

Keywords: defect, plate, natural frequency, vibration mode shapes, experimental analysis

full text

Experimental Research on the Influence of Vibration on Knee Mobility
Radu Panaitescu-Liess, Cristian Pavel, Florin Bausic

Besides hand - arm system, the vibration can enter in the human body through the feet, too. In these case - when the subject was in a standing position and the vibrations have a vertical component - longer exposures may cause disease of joints, lower extremity and serious disorders of the cerebral blood vessels, internal organs and circulatory system. This paper focused on the influence of vibration on knee mobility. We used a MediTouch system which consists of a motion capture device (an ergonomic leg brace) and a dedicated software.

Keywords: MediTouch, ergonomic leg brace, knee, joints, mobility

full text

Simulation of Static Behavior of Corroded Pipes in Operation, Reinforced Elastic
Ioan Golumbu, Cristian Golumbu, Peter Lorenz

The pipes used for transport in chemical, nuclear or siderurgical domains, undergoes a strong internal abrasion as well as an external mechanical stress corrosion. Determination of the effective thickness of the wall is made with non-destructive ultrasound. Because of the danger of brittle fracture pipes 20-40 years old in operation, a weld consolidation solution with high residual tension is inadequate. Original solution applied in industry and certified on the basis of simulations is based on outer cuff bolted.

Keywords: stress concentrators, corrosion, sleeve, pipe

full text

Calculation of the Pipe Work Concentrator Equipped with Rectangular Openings
Ioan Golumbu, Cristian Golumbu, Dorian Nedelcu, Peter Lorenz

The coefficients of stress concentrators, used for most car bodies are known and published in the literature. There are no data on how big is the effort concentrator for tubes fitted with rectangular openings. The aim of the present work is to make available quickly and economically for the design engineer, values used in design and execution without making complicated simulations with numerical methods.

Keywords: stress concentrators, finite element analyse, pipe

full text

Numerical Monitoring of the Dynamic Behavior in Frequency of the Parametric Systems in Forced Vibration Regime
Polidor Bratu

The aim of the paper is to present a consistent monitoring method which can be used on construction sites for a rapid assessment of the work quality. The starting point is represented by the evolution processes with forced vibrations considering a system with one degree of freedom and the rheological model of Voigt-Kelvin whose elastic and viscous values can change during the technological process, in real time. Response functions are analyzed at the passing of the dynamic system from one state to another and the resulted families of curves are plotted.

Keywords: damping, response functions, parameterization

full text

Dynamic Response of a System under Anti-Vibration Forced Regime Depending on the Settlement Angle of the Elastomeric Isolators
Carmen Alexandru

For a number N of elastomeric elements grouped in parallel, but mounted at an angle alpha between the compression axis and the vertical axis, the total stiffness should be assessed accordingly. The vibration transmissibility will be determined for two borderline cases, so that intermediate values can be evaluated for an anti-vibration isolation techniques solution.

Keywords: elastomeric elements, transmissibility, isolation degree

full text

Correlation of the Process of Concrete Compaction through Vibration with the Internal Dissipation of the Energy
Ramona Pintoi

Through the correlation of the compacting process with the vibration parameters, the compaction of the fresh concrete is optimized. The employed dynamic model is a linear viscous one. The dissipative energy in the vibrated concrete is given by the vibration parameters and the hysteresis loop is determined analyzing the dissipative energy in correlation with the degree of concrete compaction.

Keywords: hysteresis loop, vibration parameters, concrete compaction

full text

Calibration of System Input Volume and Non-Revenue Water Index in Edo North, Nigeria
Philipa O. Idogho, Olotu Yahaya

Water scarcity is a serious problem in developing world. It could be physical scarcity or economic water shortage. The output of physicsbased study conducted in Edo North, Nigeria revealed that physical water losses in the water distribution network have compounded the accessibility and affordability of safe drinking water. Water supply and loss variables such as Water Supply (WS) Physical Water Loss (WL?) Apparent Water Loss (WLE) Water Loss Reduction Index (WLRI) and Available Water (AW) were mathematically modeled to produce realistic and efficient water loss management and improve water revenue. The result of the modeling iterations show that the average physical and apparent losses of 4,000m3 and 2,700m3 of (WL?) and (WLE) correspond to 13,200m3, 6,400m3 and 0.5 of WS/SIV, AW and WLRI in 2007. Strong indication exists between the WLRI for both physical and apparent losses with the coefficient of determination R2=0.83 and 0.99 respectively. This relationship shows that more water is being lost through real loss with average total of 59.2% and 40.8% of apparent losses. However, a reduction of Total Non-Revenue Water (TNRW) from 50.7% to 10.6% was recorded between 2007 to 2011. This reduction led to a total increase of 4,400m3 of Revenue Water, decrease in Non-Revenue Water reduction cost from 36% in 2007 to 7% in 2011 and saving of US$17,400 which could be used to provide health facility for malaria treatment for 14,500 people on daily basis. Water efficiency, and particularly drinking water loss, is a serious issue which has significant financial and economic depression; awareness in this respect is totally unrecognized by both individual and governmental sector. Generally, long-term strategies towards the reduction of water losses should continue to be sustained by Edo State government, donor agencies and some private sectors in the area of water supply in order to support the fulfillment of the Millennium Development Goals, control of leakage and water losses.

Keywords: Physical loss, Apparent loss, Water Reduction, Revenue, Index, Available Water, leakage

full text

Modal Analysis of a Building with Dynamic Behavior of an Elastic Constrained Rigid, Subjected to Seismic Actions
Madalina Calbureanu, Raluca Malciu

This paper presents the modal analysis for different kinds of buildings having symmetry around Y-axis. This study includes the dynamic behavior of buildings considered as elastic constrained rigid subjected to seismic actions. The results are interpreted for two different kinds of buildings – one with symmetry around X-axis and another one nonsymmetric.

Keywords: seismic actions, dynamic behavior, elastic constraints

full text

Studying the Mechanical Properties of Graphynes Using Molecular Dynamics Simulations
Tayyeb PourReza, Navid Bozorgan, Amin Farzin, Saeed Roohi

Molecular dynamics simulations are used to study the mechanical properties of graphynes. To study the effect of atomic structure and graphyne size on the Young’s and bulk modulus, armchair and zigzag nanosheets with different side lengths and aspect ratios are considered. It is shown than the fracture of armchair graphynes occurs at larger strains. Comparing Young’s modulus of armchair and zigzag nanosheets with a constant aspect ratio, it is observed that the value of side length have not significant effect on the Young’s modulus of graphynes. Besides, the schematic of graphynes axial and biaxial loading at different strains is is shown that fracture propagates in a linear pattern.

Keywords: Graphynes; Mechanical properties; Molecular dynamics simulations

full text