Volume 1, No. 12 (2006)
Articles
ADAPTIVE CONTROL ALGORITHM IN WIND TURBINE SPEED REGULATION
ABABEI ŞTEFAN
Wind turbines require active control systems to operate at variable rotational speeds. As turbines become larger and more flexible, advanced control algorithms become necessary to meet multiple objectives such as speed regulation, blade load mitigation, and mode stabilization. At the same time, they must maximize energy capture. The number and variability of influence factor in wind turbine regulation have made it necessary to develop an adaptive control algorithm. This algorithm is presented in this paper.
EXPERIMENTAL INVESTIGATION OF TOOLS LUBRICATION INFLUENCE ON SPRINGBACK EFFECT OF A U-SHAPE PART MANUFACTURED BY TAILOR WELDED STRIPES
ALBUŢ AURELIAN
In this study, the influence of tools lubrication on springback effect of a U- shape part manufactured by tailor welded stripes was investigated. Final shape of the parts manufactured by tailor welded stripes is greatly affected by springback effect. The intensity of this phenomenon depends on the parameters of the forming process. This paper work is trying to reveal the role that tools lubrication has on the springback. The tailor welded strips were joined by laser welding process and consisted of two materials, FEPO and E220 steel.
INVESTIGATION BY SIMULATION OF TOOLS LUBRICATION INFLUENCE ON SPRINGBACK EFFECT OF A U-SHAPE PART MANUFACTURED BY TAILOR WELDED STRIPES
ALBUŢ AURELIAN
This research study is trying to reveal the influence of tools lubrication on springback effect of a U-shape part manufactured by tailor welded stripes. Final shape of the parts manufactured by tailor welded stripes is greatly affected by springback effect. The intensity of this phenomenon depends on the parameters of the forming process. The influence of tools lubrication on the final part springback is examined using the simulation by finite element method. The tailor welded strips have as based materials FEPO and E220 steel.
CONTROL OF SPRINGBACK BY USING AN ARTIFICIAL NEURAL NETWORK MODEL
AXINTE CRINA
One of the greatest challenges of manufacturing sheet metal parts is to obtain consistent parts dimensions. Springback, the elastic strain recovery in the material when the tools are removed, is the major cause of variations and inconsistencies in the final part geometry. Obtaining a consistent and desirable amount of springback is extremely difficult due to the non-linear effects and interactions of process and material parameters. In this work, the ability of an artificial neural network model to predict optimum process parameters and tool geometry which allow to obtain minimum amount of springback is demonstrated, for a simulated cylindrical deep-drawing process.
FOURIER TRANSFORMS IN EARTHQUAKE ENGINEERING
BURCĂ GENOVEVA, SPĂTARU CĂTĂLINA
In this paper we present some Fourier techniques which are one of the most important methods in data processing and analysis of Earthquake Engineering and in strong motion seismology.
AN ABRASIVE WEAR MODEL FOR COMPOSITE MATERIALS
CĂLIMAN RADU, OLARU IONEL
A simple physically-based model for the abrasive wear of composite materials is presented based on the mechanics and mechanisms associated with sliding wear in soft (ductile)- matrix composites containing hard (brittle) reinforcement particles. The model is based on the assumption that any portion of the reinforcement that is removed as wear debris cannot contribute to the wear resistance of the matrix material.
AN ALUMINUM MATRIX NiTi FIBER-REINFORCED SMART COMPOSITE
CĂLIMAN RADU, OLARU IONEL
The purpose of this study is to provide a numerical method to model the constitutive behavior of aluminum matrix NiTi fiber-reinforced smart composite along the fiber direction; in the present approach, pseudo-elasticity, shape-memory, and strain-hardening effects have been taken into account. During phase transformation, the strain-temperature relation of NiTi fibers has been assumed to be linear. Hence, the incremental stress-strain relationship of the fibers has been derived for each temperature range where phase transformation lakes place.
ANAEROBIC PROCESS UPON THE UTILIZATION OF THE BIOLOGICAL SLUDGE IN A DOMESTIC WASTE DEPOSIT
CIOBANU DOMNICA, LEONTE MIHAI, TULBURE MONICA
The anaerobic process existing into the biodegradation of the domestic waste can be accelerated by an addition of biological sludge, having the role of a process activator. An addition of 20 – 25% biological sludge determines the decrease of the biodegradation period with 32%. At the end of the process the ration C/N has values of 17,8 – 18,2%, values which can direct the utilization of the waste for punching.
TIMKEN TAPERED ROLLER BEARINGS
CRISTEA ION, GEAMĂN VIRGIL
The paper concerns the use of polymer additives for improving different characteristics of lubricants required in running of mechanical systems – especially tapered roller bearings. The macromolecular matter dispersed into the oil contribute to increase of lubricant film thickness and reduce the risk of damage by scuffing of the contacting surfaces.The purpose of this paper is to investigate the performances obtained in lubrication of concentrated contacts by using polyethylene as additives for the lubricant oil used for an four-high mill.
THE PARTICULARITIES OF THE FINAL HEAT TREATMENT MADE ON BLANKS FROM ALUMINIUM ALLOY
CRISTEA ION, GEAMĂN VIRGIL
This paper presents the results of some experiments regarding to the influence of the final heat treatment made on DURAL - aluminium alloy, before and after isostatic compaction. There are presented the conclusions of these experiments and there are proposed new technologies with positive effects over the specific industry.
AUTOMAT SYSTEM FOR THE ORIENTATION OF SUN CAPTURES
CULEA GEORGE
The paper present a rentable solution through which it assured a maximum illumination of the solar panels. For a maximum irradiation of the capturing aria, it must be placed perpendicular on the incident light raw. This objective was realized by the orientation of the panel after the relative movement related to earth of the sun. The panel will follow the sun based on an algorithm for positioning, all the time it is in the visibility zone. The selected solution for the orientation of the panels it based on two feedback positioning systems, one for the Elevation angle and one for the Azimuth.
CONSIDERATION ABOUT BRAZED PLATE HEAT EXCHANGER
DROB CĂTĂLIN, OLARU IONEL
The compact size of brazed plate heat exchangers means lower shipping and installation costs, and their lightweight design makes maneuvering much easier than conventional heat transfer devices. The brazed plate heat exchangers are assembled from a very small number of machine formed parts, resulting in significantly less manufacturing time and reduced costs to the end user.
QUALITY MANAGEMENT IN THE MAINTENANCE OF TECHNICAL MECHANICAL SYSTEM
FLEŞER TRAIAN
The investment in a preventive maintenance program repays a company in longer technical systems life, smoother operation, planning, scheduling. Hence, there results the maintenance responsibilities field: preserving the productive potential, providing the technical infrastructure, environment protection, health and safety. The technical systems in the thermoenergetics, chemical, petrochemical industries, inclusively development of materials and afferent components. A version of the application block scheme of the system is presented. For the effective application particularly rigorous actions are stipulated in the technical and economical field, available for the user. This leads to the analyses of the present concepts in EU.
THE RIGIDITY OF THE CALENDER WITH TWENTY CYLINDERS
FLORESCU DANIELA, FLORESCU IULIAN
The rigidity of the cage is one of the main criteria, which defines the quality. In fact, it decides in what way the variations of the technological conditions can affect the product. The rigidity of the cage is defined by the relations between the changes made in the force of laminate and the elastic distortions that correspond to the cage.
THE CERAMIC PRODUCT FOR PRESSURE MEASUREMENT
FLORESCU IULIAN, FLORESCU DANIELA
The significant advances in materials science in recent decades have not only brought us silicon wafers, PTFE coating and heat shields for the space shuttle, but have also perfected the industrial ceramic.
RECOVERY OF METALS FROM SPENT CATALYSTS 1. CATALYSTS MANAGEMENT AND SPENT CATALYSTS SOURCES
GAVRILĂ LUCIAN
Catalysts are indispensable in many chemical processing industries for routine production of ammonia, nitric acid, sulfuric acid, methanol, formaldehyde, gasoline, diesel fuels, jet fuels, heavy oil hydrocarbons, petrochemicals and plastics. During processing, catalysts will become contaminated with impurities and become deactivated. When that happens, they are usually sent for regeneration where contaminants are removed. Ultimately, they will be contaminated in a manner and at a level that makes regeneration impractical. At this stage, catalysts are considered “spent” and they may pose significant environmental problems, as landfill disposal is no longer accepted as best practice. The paper provides an overview on the spent catalyst sources, level and potential hazard, highlighting the actual trends in catalysts management.
INSTALLATION TO REALIZE THE CRYOGENIC HEAT TREATMENTS
GHEORGHIAN MIRELA, CIUCESCU DORU
The heat treatment under 0?C (273 K) is a continuation of the quenching at negative temperatures, especially at those inferior to that of the Ms point. The aim of this treatment is the complete transformation of residual austenite in martensite. It is applied to steels with carbon content greater than 0,6%C, at which the Ms point is situated between -3?C (200K) and -93?C (180K) and to alloy steels, at which the Ms point is situated between -100?C (173K) and -140?C (133K). In the paper is described an installation for realizing the cryogenic treatments, which use an frigorific agent prepared outside-liquid nitrogen.
ENERGY MANAGEMENT AND ENERGY COST MINIMIZATION
HAZI ANETA, HAZI GHEORGHE
In this paper there are presented the key components for energy cost minimization: monitoring, load shedding and load forecasting. These are energy management system components, too. It then demonstrates applications of them in the context of energy supply contract in a company.
SOFTWARE FOR NETWORK ELECTRICITY BALANCE
HAZI GHEORGHE, HAZI ANETA
This paper present two software for electricity balance of complex network. The first software calculates successively permanent regimes and makes sum of input and output electricity for every load step. The second software uses statistical characteristics of nodes loads. Electricity is measured or estimated and energy losses are determined statistically. There are shown results obtained for a test network.
POWER VARIANT FOR EVALUATION OF SOLICITATION OF CIRCULAR AND PLANE PLATES WITH RADIAL RIBS (II)
IATAN RADU, POPA CARMEN
This paper continues the study of deformation and stresses state in circular and plane plates with radial ribs which are situated on one face and it tackles the power method illustrated by [1]. This paper presents the evaluation expressions of stresses both in the base plate and ribs, under the influence of an uniform distributed pressure on the face without ribs of the plate. The mentioned analysis is produced for the plate with the peripheral outline which is rigid fixed, respectively leaned simple.
QUANTIFICATION ENVIRONMENTAL ASPECTS BY FEED-FORWARD BACKPROPAGATION NEURAL NETWORK
JOVANOVIÆ JELENA, ZDRAVKO KRIVOKAPIÆ, ALEKSANDAR VUJOVIÆ
The contribution of this paper is directed towards environmental aspects quantification phase where new method based on neural network was initiated. The method should provide sufficient objectiveness and accuracy in assessment of environmental impacts for all types of organization and it is based upon the specificity of available mathematical models used by certified organizations in SCG. Taking into account significance of the request 4.3.1, “Environmental aspects” in ISO 14001 the arbitrariness and insufficient preciseness in the procedure of quantification of aspects and impacts on environment favoured by the standard encouraged the authors of this paper to initiate research in this field on the basis of artifical neural network.
CONTRIBUTIONS REGARDING THE USE OF OATS FLOUR AND BY- PRODUCTS OF MILK INDUSTRY TO OBTAIN BAKERY PRODUCTS
LEONTE MIHAI, CIOBANU DOMNICA, TULBURE MONICA
The capitalization of cereals type oats flour and by- products of milk industry, become a national problem to obtain the dietetic bakery products. The addition of oats flour in mixture with wheat flour type 650 and by- products of milk industry, contribute to obtain the dietetic bakery products with reduced gluten content.
ISSUING THE PATTERN OF THE DOUBLE SUPPLY ASYNCHRONOUS MACHINE USED IN AN ELECTRICAL WIND POWER STATION
LIVINŢI PETRU
The wind energy belongs to regenerating energies. It results from [1] that currently 80% of the new wind power stations are equipped with asynchronous machines with double supply. (MADA). This work is establishing the simplified mathematical pattern of an asynchronous machine with double supply and orientation by the stator flow. Through using the SIMULINK program, in the MATLAB environment, the block diagram has been determined the simplified pattern of an asynchronous machine with double supply and orientation by the stator flow.
A CROSS FLOW MICRO HEAT EXCHANGER DESIGN
OLARU IONEL, CĂLIMAN RADU
Microfabrication techniques and scale-up by replication have fueled spectacular advances in the electronics industry and more recently in microanalysis chips for chemical and biological applications. Microfabrication also raises new opportunities for applications of the reaction engineering toolbox. The cross flow micro heat exchanger can transfer more heat/volume or mass than existing heat exchangers within the context of the design constraints specified.
A THEORETICAL STUDY ABOUT MICRO HEAT EXCHANGERS
OLARU IONEL, CĂLIMAN RADU
Applications in thermal and chemical process engineering may benefit from microstructure devices such as micro heat exchangers, micromixers, and microstructure reactors when high heat and/or mass transfer rates are mandatory and where small sizes of the devices are of advantage. The characteristics, advantages, and potentials of microstructure devices with regard to improved and novel chemical and thermal process control have been documented in various publications.
A THEORETICAL STUDY ABOUT MICRO HEAT EXCHANGERS
OLARU IONEL, CĂLIMAN RADU
Applications in thermal and chemical process engineering may benefit from microstructure devices such as micro heat exchangers, micromixers, and microstructure reactors when high heat and/or mass transfer rates are mandatory and where small sizes of the devices are of advantage. The characteristics, advantages, and potentials of microstructure devices with regard to improved and novel chemical and thermal process control have been documented in various publications.
RESEARCH REGARDIN THE ENERGY CONSUMPTION AT GRINDING THROUGH BROKEN A LEGUMES WITH VARIABLE TEXTURE
PANAINTE MIRELA, NEDEFF VALENTIN, MOŞNEGUŢU EMILIAN, SAVIN CARMEN
The grinding process of vegetable products with variable texture it’s complex, thing what is explain from fact that grinding action are submissive inhomogeneous body like size and with differences in physics feature of different parts. In case of products with variable texture (fruits and vegetables), texture which variation from hard until as soft texture, so crumbling process then and actives work mechanism of grinding varied very much, thus can affirm that grinding operation it’s one the most expensive operations from food industry.
DIMENSIONING OF A CYLINDRICAL HIGH-PRESSURE MOVABLE GASKET USING THE FINITE ELEMENTS METHOD
PETROV MIROSLAV, SLAVCHEV HIRSITO
Special configurations of gaskets are used in hydro systems working at extremely high pressures. The present article deals with such a movable cylindrical gasket that comprises a body – thick-walled tube and a cover –thin- walled tube in the gasket area. Relations are derived concerning the inner stress state of the thick-walled tube depending on the outer diameter of the tube facilitating the choice of the latter. The alterations of the values of the stresses in the contact surface, the body and the cover are examined using the Finite Elements Method (FEM). Some constructive suggestions are presented in the article that will lower the values of the contact stresses in the cylindrical gasket.
STATES AND PARAMETERS ESTIMATION OF THE ASYNCHRONOUS MACHINE BY USING THE OPTIMAL OBSERVERS. PART I – ESTIMATION OF THE FLUX COMPONENTS BY USING A LUENBERGER OBSERVER
PUIU-BERIZINŢIU MIHAI, PUIU GABRIEL PETRU
THIS PAPER DISCUSSES THE ASYNCHRONOUS MACHINE FLUX ESTIMATION BY USING A COMPLETE ORDER ESTIMATOR (LUENBERGER ESTIMATOR). THERE IS PRESENTED THE STRUCTURE OF THIS OPTIMAL OBSERVER TYPE AND THE NUMERICAL IMPLEMENTATIONS ALGORITHM. IT IS PERFORMED THE TIME-DISCRETE STATE-SPACE MODEL OF THE ASYNCHRONOUS MACHINE AND THE ALGORITHM FOR THE NUMERICAL IMPLEMENTATIONS OF THE LUENBERGER STATE ESTIMATOR. THE ESTIMATOR OF THE ROTOR AND STATOR FLUX IS SIMULATED USING THE MATLABSIMULINK FILES. FINALLY, THE CONCLUSIONS OF THIS ESTIMATOR STUDY ARE PRESENTED.
STATES AND PARAMETERS ESTIMATION OF THE ASYNCHRONOUS MACHINE BY USING THE OPTIMAL OBSERVERS PART II – ESTIMATION OF THE ROTOR RESISTANCE BY USING THE EXTENDING KALMAN FILTER THEORY
PUIU-BERIZINŢIU MIHAI, PUIU GABRIEL PETRU
TUNING THE ROTOR RESISTANCE OF THE ASYNCHRONOUS MACHINE IS VERY IMPORTANT, ESPECIALLY WHEN IT IS USED TO IMPLEMENT THE FIELD- ORIENTED CONTROL (FOC) IN WHICH THE ROTOR RESISTANCE IS ONE OF MAIN PARAMETERS. A METHOD FOR THE ESTIMATION OF THE ASYNCHRONOUS MACHINE ROTOR RESISTANCE BASED ON THE KALMAN FILTER THEORY IS DISCUSSED IN THIS PAPER. THERE IS PRESENTED THE KALMAN FILTER GENERAL THEORY AND ITS APPLYING WAY FOR THE IMPLEMENTATION OF AN OPTIMAL RECURSIVE OBSERVER, NAMED EXTENDED KALMAN FILTER (EKF). THE OBSERVER WITH EKF FOR THE ROTOR RESISTANCE ESTIMATION IS SIMULATED BY USING MATLABSIMULINK FILES, AND THE CONCLUSIONS OF THE SIMULATION STUDY ARE PRESENTED.
ATOMIZATION OF CONDUCTING LIQUIDS IN AN ELECTRIC FIELD
SAJIN TUDOR, BUZDUGĂ ŞTEFANIA ROXANA
A new method of conducting liquid atomization is worked out on the base of water bubbling in electric field and studied. Experimental dependencies of formation intensity, mass mean charge and drop size on the field strength and bubbling gas rate are obtained. The aerosol movement dynamics in a parallel-plate capacitor is investigated.
CREATION OF BIOLOGICALLY ACTIVE AEROSOLS BY METHOD OF ELECTROACTIVATION AND ATOMIZATION OF WATER IN ELECTRIC FIELD
SAJIN TUDOR, BUZDUGĂ ŞTEFANIA ROXANA
A new method of conducting liquid atomization is worked out on the base of water bubbling in electric field and studied. The aerosol movement dynamics in a parallel-plate capacitor is investigated. A life stimulating and bactericidal properties by means of a preliminary treatment of water in a diaphragm electrolyzer is proposed.
THE DETERMINATION EXPERIMENTAL OF VISCOSITY STRUCTURAL FOR NON-NEWTONIAN MIXTURES
SAVIN CARMEN, NEDEFF VALENTIN, ZICHIL VALENTIN, PANAINTE MIRELA, MOŞNEGUŢU EMILIAN
The experiments was realized for an mixture with average consistence, S-L type, with solid phase participation (meat) in 50% proportion and liquid phase participation (water) in 50 % proportion for an constant revolution ( n=90 rot/min) and fill degree of mixing tank by 25 % proportion. The experimental determination was realized by an stall which allow the obtaining of non-newtonian mixtures in laboratory conditions.
PLAN MECHANISMS SYNTHESIS WITH THE FACILITIES OF “WATT” EDUCATIONAL SOFTWARE
SILAV CONSTANTIN
Most available software on dynamics or kinematics is used to analyze the behavior of a mechanism. However, to start with, the Engineer has to `invent` a mechanism before he can analyze it. This is not a trivial task. With available methods and handbooks this can take several days if not weeks. Watt Mechanism Design Tool solves this problem. From specification of the required movement and constraints on pivot locations, transmission angles, dimensions, it searches and finds a variety of approximate or exact solutions within minutes. The user can interactively set specifications, evaluate the offered solutions and add or relax constraints.
ECONOMICAL CONSIDERATIONS FOR IMPROVING THE DURABILITY OF THE CUPOLA LINING
SIMIONESCU GHEORGHE, CIUCESCU DORU
The cupolas have a good thermal efficiency because the metal to be melted is in direct contact with burning fuel. One very important problem of this melting furnace is the durability of the lining. Due to the fact that the repairing needs bricks but also mortar, the combination of these two kinds of refractory materials of different prices, the establishment of a good proportion is obvious. This paper presents some economical data to establish the optimum alternative in order to improve the durability of cupola lining, obtaining in the same time an important economy.
PROBLEMS AND METHODS OF FORCE CONTROL BY CLASSIC AND MECHATRONIC APPROACH
ŽIVKOVIÆ MILUTIN *, GOLUBOVIÆ DRAGAN **
The paper analyzes force increase above the defined values at devices with hydrostatic drive, which is a special feature of the system where resistance in working stroke of the cylinder suddenly increases. By analyzing the variable solutions and influential parameters the methods for eliminating this effect are suggested. Proportional or servo valves, unlike conventional solutions for force control, enable its fine control aside from possible obstructions such as: `` fluctuation of pressure", variable load as well as other influences related to the state of working fluid. This solution, installed at the Faculty of Technical Sciences in Èaèak, shows, beside other possibilities, the method for solving these problems by mechatronic approach. Owing to installed instrumentation and control equipment it offers various program stresses so it presents a real example of mechatronic system.