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

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Anul XVII (2010), Nr. 1




Direct Search Based Strategy for Obstacle Avoidance of a Redundant Manipulator
Cornel Secară, Dan Dumitriu

This paper presents an iterative direct search based strategy for redundancy resolution. The end-effector of the redundant manipulator achieves the imposed task of following the contour of a curve, while fulfilling two other performance criteria: obstacle avoidance and minimization of the sum of joint displacements. The objective function to minimize is the sum of joint displacements, while the obstacle avoidance and end-effector task are expressed as non-linear constraints. The proposed direct search based strategy is iterative; the joint configura-tion computed in the previous step represents the current point around which the generalized pattern search algorithm is successfully performed.

Keywords: redundant manipulator, direct search strategy, obstacle avoidance

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Aspects Regarding Data Processing Obtained from Measurements for Braking System Verification of Winding Installation Machines
Vilhelm Itu, Wilhelm W. Kecs, Francisc Toth, Ştefan Jakab

The paper presents aspects on data processing obtained following measurements and recordings made in view of verification of braking system of winding installation machines. To exemplify these aspects, braking system verification of winding installation machine at Shaft 2 in Lupeni Mining Plant and the braking system of winding installation machine of Central Shaft at Petrila Mining Plant were studied.

Keywords: data processing, winding installation machines

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Considerations Concerning the Dynamics of Vibratory Mills Used in Powders’ Mechanical Milling Process
Radu Panaitescu-Liess, Amelitta Legendi, Cristian Pavel

Dynamic mechanical milling process in a powder mill was studied by analyzing the vibratory effects of vibration and shock phenomena on the material microstructure ground. During the milling process, there were noticed both distinct modes of ball motion: the one generated by the periodic vibration and the one produced by chaotic vibration.

Keywords: ivibration phenomena, collision, impact force

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Analysis of a Mechanical System’s Dynamic Properties by Vibrations Measurements
Radu Panaitescu-Liess, Amelitta Legendi, Cristian Pavel

This paper aims to present some theoretical notions about the solution of the reverse problem in the dynamic response study of a mechanical system. Thus, by measuring vibration, some dynamic properties of the mechanical system considered can be determined.

Keywords: mass, stiffness, damping, measuring vibration

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On the Nanoindentation of the Carbon Nanotubes
Petre P. Teodorescu, Veturia Chiroiu, Ligia Munteanu, Valeria Moşneguţu

A new inverse approach is proposed in this paper, which combines elements of nonlocal theory and molecular mechanics, based on the experimental results available in the nanoindentation literature. The effect of the inlayer van der Waals atomistic interactions for carbon nanotubes with multiple walls (MWCNT) is included by means of the Brenner-Tersoff potential and experimental results. The neighboring walls of MWCNT are coupled through van der Waals interactions, and the shell buckling would initiate in the outermost shell, when nanotubes are short. The nanoindentation technique is simulated for the axially compressed of individual nanotubes, in order to evaluate the load-unloaded-displacement, the curve critical buckling and the appropriate values for local Lamé constants.

Keywords: nanoindentation, carbon nanotubes, buckling, Brenner-Tersoff potential, van der Waals force, kink

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The Simulation of the Functioning of a Hybrid Vehicle
Dinel Popa, Nicolae Pandrea

In the paper we present a functional model and its mathematic modeling of the movement of the mechanism that simulates the functioning of a hybrid vehicle. The mechanism used for the coupling of three electric engines of continuous current with permanent magnet stator is a planetary mechanism with a double satellite. The functional model operation is ensured by an electronic module which allows the supply voltage variation of electric motors and an electronic device. In order to study the movement of the mechanism from a mathematical point of view we have designed a mathematic model with two degrees of freedom. We obtain the solution in transition phase and in permanent phase after obtaining the differential equations of motion using Lagrange's equations.

Keywords: hybrid, functional mechanism, power sources, planetary mechanisms, differential equations

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Optimisation Methods for Cam Mechanisms
Claudia – Mari Popa, Dinel Popa

In this paper we present the criteria which represent the base of optimizing the cam mechanisms and also we perform the calculations for several types of mechanisms. We study the influence of the constructive parameters in case of the simple machines with rotation cam and follower (flat or curve) of translation on the curvature radius and that of the transmission angle. As it follows, we present the optimization calculations of the cam and flat rotation follower mechanisms, as well as the calculations for optimizing the cam mechanisms by circular groove followers’ help. For an easier interpretation of the results, we have visualized the obtained cam in AutoCAD according to the script files generated by a calculation program.

Keywords: CAM, curvature radius, constructive parameters, pressure angle, circular grove

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On the Efficiency of a Base Isolation System
Ana-Maria Mitu, Tudor Sireteanu, Daniel Baldovin

IThe aim of this paper is to present the analyses of the efficiency for a base isolation system. To portray the hysteretic behavior of the devices used for seismic protection the Bouc-Wen model is used. The non-linear first order equation which can describe the evolution of force de-veloped by one device for almost any loading pattern are added to the system of equations which models the dynamical behavior of the pro-tected building. Using Matlab-Simulink software, the model are employed to investigate the efficiency of the base isolation devices by comparing the seismic response of protected and unprotected buildings subjected to strong seismic actions.

Keywords: hysteretic characteristics, base isolation system, Bouc-Wen model

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Rigidity Influence of Suspended Cable on Free Vibration Modes
Marcel Migdalovici, Tudor Sireteanu, Emil Matei Videa

The problem of vibration control of overhead line conductors subjected to laminar transverse wind, inducing stationary vibrations by Karmán effect is of high importance due to consequences upon these structures lifetime and service. We consider the cable model as Euler-Bernoulli beam that include the influence of cable rigidity and that respect the author condition which detaches the suspended cable model of the beam model with viscous, hysteretic or dry friction internal damping hypothesis. The original analytical expression of the free vibration modes and the resonance frequencies equation for the cable with clamped extremities has produced. Some experimental aspects are underlined in the paper.

Keywords: Euler-Bernoulli beam, suspended cable model, vibration mode, damping, analytical solution

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A Study of Annular Plate Buckling Problem with Tension Loaded at Inner Edge
Syed Noh, Mostafa Abdalla, Waleed Fekry Faris

The buckling problem of annular plate with only one edge (either inner or outer edge) constrained is formulated and presented in this paper. The boundary condition is simply supported inner edge-free outer edge. The results are compared between the FEM results obtained using ABAQUS and results reported in literature. The results shows good agreement for critical buckling load, mode shapes and stress distributions.

Keywords: piezoelectric, annular, buckling, methods of multiple scales

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The Ultrasound Propagation Analysis through Two Mediums in Case of High Energy Piezoelectric Transducer
Grigore Liviu Odobescu

The high energy ultrasound it is generated by piezoelectric elements which are excited from electric signal obtained from an electronic generator. The transmission of this high energy it is obtained by transmission element or concentrator element in function of what we want to do with this energy especial utilized in no conventional technology. The efficiency work is very important aspect because the energy utilizes has high values. In this paper it is presented methods to calculate the elements components necessary to generates and transmits the high ultrasound energy: piezoelectric transducers and transmission / concentrator elements. It is presented the experimental results obtained with the theory presented. Original contribution consists by method used and suggestive graphics for appreciation of variations parameters.

Keywords: ultrasound, vibration, propagation, piezoelectric transducer

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The Analyzing of Ultrasound Propagation Wawes through a Piezoelectric Transducer in Function of Acoustic Charge
Grigore Liviu Odobescu

The nature of acoustic charge, which works with an electronic generator to generate high intensity ultra-acoustic field is very various in function of application used [2]. The values of elements from equivalent scheme may be to vary in time in function of technologic process [3]. This fact determines the variation of accord frequencies and value of acoustic charge. In this manner the efficiency can be modified in time if it no take measures to minimize these influences of complex impedance that works with electronic generator [4]. In this paper it is presented a method to analysis the influence of variation of acoustic charge and to minimize this influences for to assure an optimum operation of electronic generator, it is presented a program to calculate the power variation in function of acoustic charge and to chart the diagram of this variation. It is presented the experimental results obtained with the theory presented.

Keywords: acoustic charge, ultrasound vibration, piezoelectric transducer

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Behavior at High Temperatures of Steel Used for Constructions (Reactions to Fire)
Eugen-Marius Afronie

The purpose of the present paper is to determine the response of main elements and resistance structures to extreme circumstances, specifically to action of conflagration, considering the temperature distribution inside structure’s elements, materials characteristics – steel for this case – following the determination of thermo-mechanic response of main elements and resistance structures.

Keywords: structure, resistance, temperature, steel

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Two Degrees of Freedom Non-linear Model to Study the Automobile’s Vibrations
Nicolae–Doru Stănescu

In this paper we present a non-linear model for the study of an automobile's vibrations. The model has two degrees of freedom and it is highly non-linear. The forces in the springs are considered to be given by a polynomial potential. The equations of motion are obtained using the Lagrange second order equations. We determined the equilibrium positions. We proved the conditions for the uniqueness of the equilibrium. In our paper we studied the stability of the equilibrium and the stability of the motion. Finally a numerical application is presented.

Keywords: non-linear, vibrations, stability, automobile

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The Equilibrium of the Solid Rigid with Constraints
Săndel Ogaru, Nicolae Pandrea, Nicolae–Doru Stănescu

In our paper we obtain the matrical equations of equilibrium for a solid rigid with constraints. These equations are deduced from the Lagrange equations. Finally we present a completely solved example.

Keywords: Lagrange equations, pseudo-coordinates

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A Kinematic Analysis of the Variable Valve Timing Mechanism with Three Elements and Continuous Valve Lift
Stelian Mihalcea

An innovating solution for throttle-free load control for spark-ignition engines is Variable Valve Timing system (VVT System, or VVA - Variable Valve Actuation System). In this paper is presented an analytic method for kinematic analysis of the valve timing mechanism with three elements, which mainly includes the camshaft, the roller rocker finger and an intermediate rocker arm. This type of mechanism ensures a continuous valve lift (VVL System) between two extreme valve heights. It is also presented the numerical example for the variable valve lift mechanism’s motion.

Keywords: Variable Valve Lift, Mechanism, Kinematic analysis

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The Predicting of the Size Effects in the Buckling of the Carbon Nanotubes
Cristian Rugină, Pier Paolo Delsanto, Veturia Chiroiu, Ligia Munteanu

It is well-known that the nanoindentation hardness displays strong indentation size effects. In this paper, the size dependence of the hardness with respect to the depth and the indenter radius for the buckling of multiwalled carbon nanotubes is investigated using the Toupin-Mindlin strain gradient theory. As expected, the indentation hardness is closely related to the depth and the indenter radius. Qualitatively, the responses of the axially compressed multiple walled carbon nanotube agree remarkable well with the experimental observations.

Keywords: Nanoindentation, carbon nanotubes, buckling, size effects, Toupin-Mindlin theory

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Dissipation Effect in the Hunting Motion Stability of Wheel Set with Elastic Joints
Daniel Baldovin, Tudor Sireteanu, Nistor Simona, , Ana-Maria Mitu

The axle hunting is a coupled lateral and yaw self oscillatory motion which is largely determined by wheel–rail contact geometry. The stability of this motion is an important dynamic problem that determines the maximum operating speed of railway vehicle. To improve the stability performances, without increasing the rail-wheel interaction forces above safety limits, elastic joints and dissipative devices are used to connect the wheelset to the bogy frame. In this paper is studied the influence of passive linear and non-linear dissipative horizontal forces on the hunting motion stability of a wheelset with elastic joints.

Keywords: Hunting motion, nonlinear dissipation, critical speed

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The Computation of the Efforts into the Plan System of the Elastic Bars which Suspends a Rigid with Constraints
Jan-Cristian Grigore, Nicolae Pandrea

One considers that the rigid with constraints acted by the external forces suported by the elatic bars embedded at the base. Under the influence of the external forces appear the connection forces and the displacements in the kinematic pairs. One deduces the mathematical model for the computation of the reactions and the displacements and one makes a numerical applications.

Keywords: rigid, constraints, elastic, joint bars

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Rehabilitation of Plant Units at Pumping Stations
Tiberiu Ştefan Mănescu, Gelu Băllan, Mihaela Dorica Stroia, Silviu Dan Avram, , Loretta Simona Chivu

During operation process, industrial pumps are subjected to wear and corrosion that often lead to various physical damages and functional faults. Although this is not a habitual case, when occurs, it is very expensive to replace the affected parts with new ones and in most of situations this isn’t the best problem solving. A way to deal with this type of problem at pumping stations is rehabilitation of plant units. The present paper describes a solution to rehabilitate worn pumps using CERAMITECH treatments based on epoxy resin and polyamine-amides reinforced with carbide and ceramic particles. Also it shows measure-ments before and after using the treatment.

Keywords: pump, treatment, characteristic curve, CERAMITECH

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Studies Regarding Design and Optimization of Mechanisms Using Modern Techniques of CAD and CAE
Marius Tufoi, Ion Vela, Constantin Marta, Adelin Ionel Tuţă

The paper presents applications of modern techniques of CAD (Computer Aided Design) and CAE (Computer Aided Engineering) to design and optimize the mechanisms used in mechanical engineering. The use exemplification of these techniques was achieved by designing and optimizing parts of a drawing installation for horizontal continuous casting of metals. By applying these design methods and using finite element method at simulations on designed mechanisms results a number of advantages over traditional methods of drawing and design: speed in drawing, design and optimization of parts and mechanisms, kinematic analysis option, kinetostatic and dynamic through simulation, without requiring physical realization of the part or mechanism, the determination by finite element method of tension, elongations, travel and safety factor and the possibility of optimization for these sizes to ensure the mechanical strength of each piece separately. Achieving these studies was possible using SolidWorks 2009 software suite.

Keywords: CAD, CAE, optimization, simulation, continuous casting

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Simulation of Oscillatory Working Tool
Carmen Debeleac

The paper presents a study of the resistance forces in soils cutting, with emphasis on their dependence on working tool motion during the loading process and dynamic regimes. The periodic process of cutting of soil by a tool (blade) has described. Different intervals in the cycle of steady-state motion of the tool, and several interaction regimes were considered. The analysis has based on a non-linear approximation of the dependence of the soil resistance force on tool motion. Finally, the influence of frequency on the laws governing the interaction in the cyclic process was established.

Keywords: cutting, soil, blade, vibrations, dynamics

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Considerations upon the Characteristic Frequency Spectra of some Road Transportation Means
Vasile Bacria, Nicolae Herişanu

The noise generated by the road transportation means is characterized by frequency spectra, acoustic pressure levels and their variations in time. The sources of vibration and noise depend on the transportation mean type. Therefore every transportation mean identifies itself by characteristic frequency spectrum and noise level. Using the recording of the frequency spectra of the transportation means, one can identify the attenuation methods of the generated noise. In this paper we pre-sent some results obtained in the study of the noise generated by the road transportation means using the frequency spectra.

Keywords: road transportation means, noise, frequency spectra

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Theoretical and Numerical Analysis for the Design of a Safety Barrier as Road Restraint System
Constantin Vasile Bîtea, Gabriel Jiga

The paper deals with a theoretical background and with numerical studies achieved on an N2 safety barrier, with normal protection. In order to determine the impact force, a model at a reduced scale was proposed. For the calculus of the dynamic load due to the impact, the corresponding maximum deflection was determined. In the same time, the equivalent stress distribution was plotted for the examined case.

Keywords: safety barrier, numerical analysis, car crash

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Comparative Analysis of Visco-elastic Models with Variable Parameters
Silviu Nastac, Adrian Leopa

The paper presents a theoretical comparative study for computational behaviour analysis of vibration isolation elements based on viscous and elastic models with variable parameters. The changing of elastic and viscous parameters can be produced by natural timed evolution demo-tion or by heating developed into the elements during their working cycle. It was supposed both linear and non-linear numerical viscous and elastic models, and their combinations. The results show the impor-tance of numerical model tuning with the real behaviour, as such the characteristics linearity, and the essential parameters for damping and rigidity. Multiple comparisons between linear and non-linear simulation cases dignify the basis of numerical model optimization regarding mathematical complexity vs. results reliability.

Keywords:Visco-elastic model, variable parameters, spectral characteristic

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Transmission Loss Assessment for a Muffler by Boundary Element Method Approach
Ovidiu Vasile

This paper investigates the acoustic performance of two cases for reactive mufflers using Boundary Element Method (BEM) analysis. Modeling procedures for accurate performance prediction had led to the development of new methods for practical muffler components in design. The transmission loss (TL) is the more widely can be easily computed with a BEM analysis. The author presents an overview of the principles and theoretical formulation of BEM for predicting the transmission loss of a muffler, the pressure and velocity distribution on surfaces of muffler. At the end of the paper is presented a comparison of two cases of mufflers for transmission loss. The predicted results agreed in some limits with the experimental data published in literature.

Keywords:muffler, transmission loss, BEM

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Methods of Simulation for Dynamic Systems with Friction
Cristina Opriţescu, Oana Petcoviciu, Mihai Ilie Toader

In this paper the contact/impact between two bodies is accentuated by simulations using the ANSYS code. In the present study has been selected the ANSYS/LS-DYNA code because it is used in the simulation of contact/impact. This computer code performs nonlinear transient dynamic analysis of three-dimensional structures.

Keywords:friction, contact, impact, mathematical model

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Intelligent Agent for Damages Detection
Darian Onchis-Moaca, Gilbert-Rainer Gillich, Zeno-Iosif Praisach, Esperanza Maria Suarez-Sanchez

We introduce in this paper an intelligent system that automatically de-tects the damage in cantilever beams called AgentMec. This agent is creating its knowledge using a database with the first ten natural frequencies of the beam damaged at pre-determined points. Using the reinforced learning, it creates the patterns to describe the behavior of the damaged beam. Then with each new vibration measurement send as input, AgentMec is able to recognize the location of the damage.

Keywords: intelligent agent, damage, identification, vibration, frequency

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Evaluation of Elastic Forces Resulted from the Impact Vehicles - Flexible Barriers

Polidor Bratu

The paper approaches initiation and finalizing of the percussion process for the system vehicle-flexible barrier basing on analytical evaluations and principle of equivalence for the mechanical resistance in case of experimental results transfer between two different containment levels.

Keywords: flexible barrier, impact, elastic deflection, equivalent actions

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Anul XVII (2010), Nr. 2




Model Equations of Shape Memory Effect - Nitinol

Daniel Amariei, Ion Vela, Gilbert-Rainer Gillich, Călin Octavian Micloșină

Even it has been already confirmed that SMA’s have high potential for robotic actuators, actuators included in space robotics, underwater robotics, robotics for logistics, safety, as well as “green robotics” (robotics for the environment, energy conservation, sustainable development or agriculture), the number of applications of SMA-based actuators is still quite small, especially in applications in which their large strains, high specific work output and structural integration potential are useful,. The paper presents a formulated mathematical model calculated for binary SMA (Ni-Ti), helpful to estimate the stress distribution along with the transformation ratio of a SMA active ele-ment.

Keywords: shape memory, modeling, actuation, thermo mechanical transfer, Nitinol

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The Way of Establishing a Relative Position for Some Production Units

Olga Ioana Amariei, Denis Fourmaux, Constantin Dan Dumitrescu

The CRAFT Method was at the basis of the development of the heuristic commuting models, in which one starts from an initial emplacement of units that is successively improved, through the successive commuting of units among them on the basis of some criteria. In the present paper we have resolved to the Facility Location and Layout module of the WinQSB program that uses the CRAFT Method in solving problems of the Functional Layout type.

Keywords: initial emplacement, efficiency, relative position, rectilinear model

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Lean Manufacturing - A Powerfull Tool for Reducing Waste During the Processes
Mihai Apreutesei, Emil Suciu, Ionela Roxana Arvinte

Lean manufacturing provides a new management approach for many small and medium size manufacturers, especially older firms organized and managed under traditional push systems. Improvement results can be dramatic in terms of quality, cycle times, and customer responsiveness. Lean manufacturing is more than a set of tools and techniques and has been widely adopted by many production companies. Lean manufacturing is a culture in which all employees continuously look for ways to improve processes. In the present article are presented the Lean Manufacturing tools, like kaizen, Kanban, poka-yoke witch a company can use to reduce the waste(muda) during a production process. The paper contains also, the most common seven types of waste from production and some examples from our daily activity.

Keywords: lean manufacturing, waste, lean tools, Kanban, leaner company

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Clusters Regarding Key Factors Affecting Changes in Accounting, Finance, Administration and Management Control
Rodica Gabriela Blidisel, Adina Simona Popa, Raimondo Lo Russo, Maria Moraru

During the last decade, important changes have occurred in public governance, which has evolved in this time from hierarchical bureaucracy to participatory governance, where the role of citizens in public decision-making process is more direct. There were performed reforms in finance, management administration and finances of public sector. Starting from the factors that influenced during the history the accounting, finances, administration and management control, we want to test the factors that affect the changes of these elements in Romanian environment.

Keywords: cluster analysis, dendogram, accounting

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Magneto Rheological Semi-Active Damper with External By-pass Circuit in Modular Structure
Alexandru Boltoşi, Cristina Opriţescu, Amalia Ţîrdea

In order to perform experimentally studies, in the paper it is presented a simple method which was elaborated to realize reliable, at low cost and reproducible semi-active dampers with magnetorheological fluids, having external magnetic circuit. The main components are common constitutive elements of industrial hydraulic and pneumatic drivers, having the supplementary advantages being manufactured in a large scale of overall dimensions and demanding minimal modifications. As accumulator, a similar type of hydraulic or pneumatic cylinder was used. The work of the whole damper can be optimized by modifying the nitrogen pressure and interior volume of accumulator. Another important advantage of this conception is the possibility to realize a modular structure composed by the damper, accumulator and magnetic field generator, interconnected by flexible elements.

Keywords: magnetorheological fluid, semi-active, by-pass circuit, modular structure

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Analytical Method to Estimate Fatigue Life Time Duration in Service for Runner Blade Mechanism of Kaplan Turbines
Ana – Maria Budai , Andrea Minda

The paper present an analytical method that can be used to determianted fatigue life time duration in service for runner blade mechanism of Kaplan turbines. The study was made for lever button of runer blade mechanism using two analytical relation to calculate the maximum number of stress cycles whereupon the mechanism work without any damage. To estimate fatigue life time duration will be used a formula obtained from one of most comon cumulative damage methodology taking in consideration the real exploatation conditions of a specified Kapaln turbine.

Keywords: fatigue, runner, blade, mechanism

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Influence of Working Environment on Fatigue Life Time Duration for Runner Blades of Kaplan Turbines
Ana – Maria Budai, Vasile Cojocaru, Camelia Jianu

The paper present an analytical analyzes refer to influence of working environment on life time duration in service of runner blades of Kaplan turbines. The study are made using only analytical method, the entry dates being obtained from measurements made in situ for a Kaplan turbine. To calculate the maximum number of stress cycles whereupon the runner blades work without any damage it was used an analytical relation known in specialized literatures under the name of Morrow’s relation. To estimate fatigue life time duration will be used a formula obtained from one of most common cumulative damage methodology taking in consideration the real exploitation conditions of a specified Kaplan turbine.

Keywords: fatigue, runner, blade, environment

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Heat Treatments and Materials Used in the Manufacturing of the Gear Wheels
Virgil Dan Cărămidaru, Ion Vela

For the reducers used for a certain application, a relative reduced number of materials joins the discussion, respectively procedures of heat treatment, the decision was taken conditioning aspects, as: functions solicitated to the transmission (movement transmission, durability, behaviour to the noise), number of the pieces and the manufacturing procedure.

Keywords: steels and cast irons, hardenability, depth of quench hardening, superficial hardness and wear resistance

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Solar Photovoltaic Plant for the “Eftimie Murgu” University of Resita
Cristian P. Chioncel, Dieter Kohake, Petru Chioncel, Ladislau Augustinov

The paper presents an application of a solar photovoltaic plant for the “Eftimie Murgu” University, with an estimation of the yearly medium energy production. The substantiation of the plant design is based on the many years measurements obtained in the laboratory for monitoring the solar photovoltaic energy of the university and the favorable conditions of promoting the energy production from renewable sources, assured in the new legislation.

Keywords: solar photovoltaic conversion, solar module, inverter, motor - generator group

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Complex Technical Solution for Renewable Energy
Cristian P. Chioncel, Leo Schiefermueller, Petru Chioncel, Nicoleta Gillich

This paper presents a complex technical solution for implementing renewable energy, namely: wind, solar photovoltaic and hydraulics. Because wind and solar photovoltaic energy have a highly random character, it is required to find solution to store the product energy for unfavorable periods, without wind or solar radiation. This could be achieved using the third type of renewable energy, the hydraulic one, obtained form an hydroelectric pumped storage plant (HPSP), located in the im-mediate vicinity of the wind and solar photovoltaic plant.

Keywords: renewable energy, wind, solar photovoltaic, hydraulic

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Noise Map - a Necessity
Adrian Chivu, Tiberiu Ştefan Mănescu

In contrast to many other environmental problems, noise pollution continues to increase thanks to industrial, social and transportation field development. The paper analyze specific aspects on the impacts of noise on health, to identify areas for priority action and remediation measures.

Keywords: urban road, traffic, noise, level, map

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The Influence of Some Factors on Maximum Depth in Electrohydraulic Forming
Liviu Coman

The paper presents the results of the author`s experimental research concerning the influence of discharge voltage of condensers battery, condensers battery capacity, discharge axis - plate distance and electrode gap on the shock wave maximal pressure and, implicit, on maximum drawing depth which can be realized to the plate, in the case of electrohydroimpulses drawing in the high voltage domain, between 20...50 kV, in a cylindrical universal discharge chamber. Are presented some considerations regarding the influence of gas bubble pressure.

Keywords: drawing depth, electrohydraulic forming, voltage, distance

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A Method to Study Thickness Reduction in Electro-hydraulic Forming of Cones
Liviu Coman, Draghita Ianici, Codruta Hamat

In this paper are presented some of the authors experimental researches connected to the electrohydroimpulses drawing of the thin conical parts made from aluminium, and also to the quality of these parts. Experimental conditions are specified and comparatively presented some results obtained for the same kind of parts, but in the case of magnetic impulses drawing (magneto – dynamic deformation). As a criterion for the quality of the parts obtained by electrohydroimpulses drawing in monoimpulse regime, the distribution of material’s thickness reduction lengthways with the cone element is adopted, for different geometries of the cone. The study is achieved for various intermediate deformation stages and discharge energies.

Keywords: cone, electrohydraulic forming, thickness, quality, drawing

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Check Interior Surfaces of the Oil Conservatories of the Power Transformers
Tiberiu Cujbă

Paper presents two experiments designed to verify traversing the inner surfaces of the oil conservatories of the power transformers. Corrosion of internal surfaces of the oil conservatories is a negative aspect, which may affect safe operation of power transformers. Rust particles thus formed, migrate vat transformer insulating oil quality worsening. To prevent such situations should be regular monitoring of the interior surfaces of the oil conservatories.

Keywords: oil conservatories, rust, insulating oil, the safe operation

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Analysis of the Transitional Process into Naval Electrical Equipment
Florenţiu Deliu, Gheorghe Samoilescu

The analysis is based on a naval power with synchronous generator and consumers of various powers. The paper presents a systemic approach to naval power systems based on mathematical models of specific generators and consumers.

Keywords: transitional arrangements, electric power system, synchronous generator, mathematical models, the shock load

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Ship Traffic Modeling and Performance Evaluation in Container Port
Branislav Dragović, Nenad Dj. Zrnić, Elen Twrdy, Dong-Keun Rooy

This paper gives ship traffic modeling and performance evaluation in container port. The basic approach used analytical and simulation models. These models are developed for impact analysis of the ship traffic and patterns of arrival ships at terminal performance. Results from both models are compared with each other. Both the simulation and analytical models were applied to evaluate the efficiency of PECT.

Keywords: ship traffic modeling, analytical and simulation models

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Calculation Method for the Displacements of Cross Sections for Unsupported Straight Bars Subjected to Axial or Torsion Loads
Viorel Goanţă

This paper discusses a method for the determination of the displacements of the cross sections for unsupported straight bars subjected to axial loads – with forces or moments. The displacements of the cross sections are determined against their initial position, as well as against the section or sections that do not displace during static loading. The section or sections that do not displace against itself or themselves during the tensile-compression load or during the static torsion load are also determined with the help of this method.

Keywords: displacement, deformation, unsupported bars, cross sections

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Study of Volumetric Efficiency for Spark Ignition Engines Using Alternative Fuels
Adrian Irimescu

One of the most important parameter for spark ignition engines is volumetric efficiency, as it directly influences specific power output. Several definitions of this parameter are studied from a theoretical point of view, taking into consideration the use of alternative fuels. The influence of using gasoline-bioethanol blends is investigated, as well as the effect of fuelling spark ignition engines with methane, liquefied petroleum gas and hydrogen. Bioethanol features the highest volumetric efficiency, while gaseous fuels cause a drop in specific power output compared to gasoline operation.

Keywords: spark ignition engines, volumetric efficiency, alternative fuels

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Computer Aided Design of Kaplan Turbine Piston with SolidWorks
Camelia Jianu

The paper presents the steps for 3D computer aided design (CAD) of Kaplan turbine piston made in SolidWorks.The present paper is a tutorial for a Kaplan turbine piston 3D geometry, which is dedicaded to the Parts Sketch and Parts Features design and Drawing Geometry and Drawing Annotation.

Keywords: Kaplan turbine piston, SolidWorks, 3D geometry

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Computer Aided Design of the Link-Fork Head-Piston Assembly of the Kaplan Turbine with Solidworks
Camelia Jianu, Ana-Maria Budai, Constantin Viorel Câmpian

The paper presents the steps for 3D computer aided design (CAD) of the link-fork head-piston assembly of the Kaplan turbine made in SolidWorks.The present paper is a tutorial for a Kaplan turbine assembly 3D geometry, which is dedicated to the Assembly design and Drawing Geometry and Drawing Annotation.

Keywords: Kaplan turbine assembly, SolidWorks, 3D geometry

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Dynamic Modelling of a Single Stage Cylindrical Gearbox
Zoltan Korka

Gearboxes are frequently used in machine systems for power transmission, speed variation and/or working direction. Dynamic modelling of gear vibration offers a better understanding of the vibration generation mechanisms as well as the dynamic behaviour of the gear transmission in the presence of gear tooth damage.

Keywords: gearbox, vibration, gears, modelling, simulation

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The Tendencies of Piece Casting from Modified Irons
Cinca Ionel Lupinca, Ileana Veronica Rigou, Cornelia Ecaterina Cornean

In this paper we have presented the metalographic studies made on the grey cast irons treated with complex modifying substances, type FeSiMgRE (Mg alloy) and their influence on the compactness degree of graphite separations. For research and experiments, a melt of grey iron was produced in an induction furnace of a capacity of 5to, starting with a metallic charge made from 100% synthetic pig iron. We realized eight practical charge made modification, by using different combinations of modifying substance and in different concentrations. The addition of carbon to the melt was performed using electrode graphite powder in the metallic charge.

Keywords: synthetic pig iron, compactness degree graphite

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Studies Regarding the Elaboration of the Manganese Austenitic Steel in the Induction Electric Furnace with Acid Coating
Constantin Marta, Ioan Ruja, Marius Tufoi, Viorel Bizau, Lenuta Suciu, Monica Rosu

The paper forwards a method of elaborating the manganese austenitic steel in induction electric furnaces with a capacity of 250 Kg having an acid furnace coating. Considering the fact that when elaborating the manganese austenitic steel sulphur can be obtained under 0.02% constitutes an additional reason to attempt the elaboration of this steel in the electric furnaces through induction with acid coating, even if the load has over 0.02% S.

Keywords: steel, austenitic, induction furnace, acid coating, elaboration, Hadfield steel

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Application of Mathematica Software for Estimate the Fatigue Life Time Duration of Mechanical System
Petru Florin Minda, Ana-Maria Budai

The paper present how we can use Mathematica to solve the equations types usually used to determinate the maximum stress cycles that can be support by a mechanical system until he will be out of use. To illustrate the type of equations used in specialized literature to estimate fatigue life time duration was chosen a specific case of mechanical structure applied to fatigue. It is about lever button of runner blade mechanism of Kaplan turbine, that in function support a very intensive alternative strain.

Keywords: fatigue, equation, algorithm, mechanism

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Methods of Reducing Emissions from Two-stroke low-speed Diesel Engines
Daniela-Elena Mitu, Feiza Memet

The worldwide focus on fuels is generally increasing because of the focus on exhaust gas emissions. General awareness of environmental issues is increasing rapidly. Diesel engine makers were first involved in questions regarding exhaust gas emissions in the field of stationary applications. A study of the exhaust gas emissions from a diesel engine represents a challenge to both the engine designer and to makers of exhaust gas treatment equipment. It is also a valuable tool for reaching a deeper understanding of the engine combustion process. These emissions control technologies, like Selective Catalytic Reduction (SCR), will help to reduce pollutants that impact our health and the health of our communities as well as reduce smog creation and other factors that contribute to climate change and global warming.

Keywords: emissions, SCR, IMO proposal

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Mathematical Model for the Contact Stress Calculation of Fluoropolymerized Toothed Wheels
Ion-Cornel Mituletu, Ion Vela, Marius Tufoi, Daniel Amariei

In this paper is presented a contact stress calculation algorithm for a new type of cylindrical toothed wheel. This new type consists in the application of a Xylan 1052 fluoropolymer film on the surface of a metal toothed wheel. Due to the fact that the steel strength, in any case is better than the plastic strength, the main issue which appears is at the contact between the two homologous flank surfaces.

Keywords: toothed wheel, fluoropolymer, stress contact calculation

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Analysis of Main Types of Vibrations at a Bridge for Passer-Byes
Attila Nagy, Levente Benedek, Mircea Bejan

The present paper deals with the dynamic mode analysis in different situations at a bridge projected for passer-byes, with the help of the AxisVM software. From the multiple studied modes of vibrations we are going to present the main vibrations which appear due to the self-weight of the bridge, due to complex forces (different loads), and also due to seismic forces (mode 1 and mode 9).

Keywords: modal analysis, complex forces, seismic forces

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Numerical Behavior Reproduction of a Truss Structure and Beam, Subjected to Concentrated Load
Nedelcu Dorian, Ianici Draghita, Nedeloni Marian, Daia Daniel

The paper deals with a numerical reproduction of a real experiment consisting of the same restraints and concentrated load applied to a truss structure and beam; the numerical reproduction was performed with SolidWorks software, where both geometrical reconstruction and finite element analysis were made. The goals of the analysis was to compare the numerical with experimental results and to evaluate the best structure using the structural response criteria.

Keywords: finite element, truss, beam, SolidWorks

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Optimal System for the Compensation of the Reactive Power with Synchronous Motors
Iuliu Petrica, Adrian Valentin Petrica

In the activity of some factories that use synchronous motors it’s nec-essary to chose and maintain the most rational value of the reactive power provided by the synchronous motors. In the context of the reduction of the energy consumption and knowing that the power of the synchronous motors is relatively great in the air compressor stations, the approach of the optimal regime of functioning of the synchronous motors, concerning the energy consumption, is necessary. Considering the synchronous motors together with the other consumers fed from the same bars and the feeder cable a functional utility, in the paper as optimising is presented the working regime that assures, on the defined above assembly, the minimal losses of energy.

Keywords: synchronous motors, energy consumption, air compressor stations

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The Compensation of the Reactive Power with Synchronous Motor
Iuliu Petrica, Adrian Valentin Petrica

An 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 synchronous motors and static converters. The compensa-tion 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: synchronous motor, reactive power, block diagram

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Air Compressor Driving with Synchronous Motors at Optimal Parameters
Iuliu Petrica, Adrian Valentin Petrica

In this paper a method of optimal compensation of the reactive load by the synchronous motors, driving the air compressors, used in mining enterprises is presented, taking into account that in this case, the great majority of the equipment (compressors, pumps) are generally working a constant load.

Keywords: air compressor, synchronous motor, reactive load

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Model for the Study of Automating a System of Pumping Water from Upstream to Downstream Hydropower Plant Using Siemens S7-200 PLC
Eugen Răduca, Mihaela Răduca, Lucian Ghinea, Aki Uyetani

This paper shows the realization of an experimental model for studying didactic use automation system pumping water from upstream to downstream hydropower. As command and control unit was used PLC Siemens S7-200.

Keywords: model, pumping, automation, PLC

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Laboratory Facilities for Testing Thermal Engines
Ioan Ruja, Florin Breaban, Constantin Marta, Marius Tufoi, Viorel Bizau

This work presents an electromechanical plant through with which is realised couples different resistant, MR (0 ÷ MRN), on the gearbox shaft of internal combustion engine. The purpose is to study the plant in phase and stationary behaviour of the main technical parameters that define the engine operation such as: torque, speed, temperature, pressure, vibration, burnt gas, noise, forces. You can take measurements to determine engine performance testing and research on improving engine thermal efficiency. With the proposed plant is built by measuring the characteristic internal combustion engines (tuning characteristic and functional characteristic) and determine the technical performance of interest, optimal.

Keywords: engine, testing, diagram acquisition, modeling

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Stationary Magnetic Field of an Electric Circuit Laid out on the Floatation of a Ship
Gheorghe Samoilescu, Florenţiu Deliu, Mircea Constantinescu

This paper presents the calculus algorithm of the intensity of the magnetic field for a maritime ship. The following have been analyzed: the magnetic field created by a live oriented right line segment and the magnetic field created by oriented circuit segments positioned across in the floating plane from a ship side to the other. The spreading of the magnetic field has been calculated for a ship with a view to compensate the vertical component of the terrestrial magnetic field.

Keywords: stationary electromagnetic field, electric circuit, ship demagnetization, impulse method

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The Stand for Determination of Service Performance in Load of a Welding Transformer Using the LabVIEW Environment
Lenuţa Suciu, Iancu Tătucu, Constantin Marta, Marius Tufoi, Cornel Hatiegan

This paper presents the way of performance’s characteristics determi-nation in load of welding transformers` performance parameters using the data acquisition systems through virtual tools. Nowadays observing the parameters of welding service and of welding instruments` charac-teristics means an important step regarding the quality of weld throat.

Keywords: transformer, start under load, welding, data acquisition

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Analytical Identification, Simulation and Analysis of Steel Solidification Process in Crystallizer
Gelu Ovidiu Tirian, Camelia Pinca-Bretotean, Cristian Abrudean, Cristian Chioncel

To do an analysis of the phenomena that lead to cracks in continuous casting process is necessary to study the heat exchange and steel solidification. Thus, this paper proposes a modeling of semi-finished product solidification during continuous cast, based on finite difference method. To validate the model, we have developed a simulation program, which had obtained important results by running comparable with the experimental results. The proposed method of modeling and simulation allows a sufficiently accurate analysis of the phenomenon of crust formation and hence the formation of solidification cracks. Although we can use it only off-line, it derives essential information necessary for designing neural system for detection of cracks and the drawing up fuzzy decision system bases rules to determine the weight correction for the cooling water flow rate and primary casting.

Keywords: analytical identification, simulation, solidification, finite difference method, crystallizer

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Microcontroller’s Applications in Driving of Industrial Robots
Marius Tufoi, Ion Vela, Constantin Marta, Mihaela-Dorica Stroia

Microcontrollers and microprocessors are distinct in that, to be able to use a microprocessor, one has to integrate peripheral components like memory chip or data transmitters-receivers, while microcontrollers have integrated all the necessary components for an autonomous operation. There is no need for additional external part because all the required ones are already incorporated in microcontroller’s capsule. Thus using microcontrollers on device construction it can be saved time and space, in terms of geometrical dimensions. The present paper describes an application regarding driving and controlling a automatic guided vehicle using microcontrollers. The kinematic curvature is performed using two guiding wheels that have immobile shafts and distinct velocities.

Keywords: microprocessor, microcontroller, robots, programming, advantages

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Sizing of Compression Coil Springs Gas Regulators Using Modern Methods CAD and CAE
Adelin Ionel Tuţă, Ion Vela, Marius Tufoi

This paper presents a method for compression coil springs sizing by gas regulators composition, using CAD techniques (Computer Aided Design) and CAE (Computer Aided Engineering). Sizing is to optimize the functioning of the regulators under dynamic industrial and house-hold. Gas regulator is a device that automatically and continuously adjusted to maintain pre-set limits on output gas pressure at varying flow and input pressure. The performances of the pressure regulators like automatic systems depend on their behaviour under dynamic opera-tion. Time constant optimization of pneumatic actuators, which drives gas regulators, leads to a better functioning under their dynamic.

Keywords: helicoidally spring, CAD, CAE, simulation, finite element

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On Dynamic Systems with Piecewise Linear Feature
Amalia Ţîrdea, Cristina Opriţescu, Mihai Toader

Impact dynamics is considered to be one of the most important problems which arise in vibrating systems. Such impact oscillator occurs in the motion with amplitude constraining stop. In the past years, this simple model has been found rich phenomena and given benefit for understanding of impact systems. Different types of impacting response, such as periodic and non-periodic oscillations, can be predicted by using bifurcation diagrams. Many mechanical systems in engineering applications represent systems which are driven in some way and which undergo intermittent or a continuous sequence of contacts with limiting motion by constraints. For example, the principles of the operation of vibration hammers, impact dampers, inertial shakers, milling and forming machines etc, are based on the impact action for moving bodies. With other equipment, machines with clearances, heat exchangers, steam generator tubes, fuel rods in nuclear power plants, rolling railway wheel sets, piping systems, gear transmissions and so on, impacts also occur, but they are undesirable as they bring about failures, strains, and increased noise levels.

Keywords: impact dynamics, oscillation, equilibrum

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Improving IT Infrastructure Management Using Nagios Open Source Package
Emanuel Zgârdea, Ladislau Augustinov

This paper presents results from adapting Nagios software package to the conditions existing at the University "Eftimie Murgu" Resita, in order to construct an integrated monitoring system of the existing active communication equipment.

Keywords: Nagios, management, IT infrastructure

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Determination of Double Flexible Toothed Wheel Length Function of Elasticity Module (E)
Daniel Vela, Dorian Nedelcu, Daniel Amariei

This paper presents the length determination modality of the double flexible toothed wheel from a toothed harmonic transmission having a wave generator with π/2 phase difference, function of the material’s longitudinal elasticity module.

Keywords: harmonic double transmission, wave generator with π/2 phase difference

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