Volume 2, No. 12 (2006)
Articles
OPTIMIZATION PROCEDURE FOR THE SPRINGBACK CONTROL
AXINTE CRINA
The paper presents an optimization procedure, based on the LMecA method, which allows to determine the optimum process parameters/tool geometry whose utilization leads to a minimum amount of springback. The analysis is made in the case of cylindrical deep-drawn parts.
EXPERIMENTAL ANALYSIS CONCERNING THE INFLUENCE FACTORS ON SPRINGBACK PHENOMENON IN THE CASE OF CYLINDRICAL DRAWN PARTS
AXINTE CRINA
Springback is one of the phenomenons that greatly affect the accuracy of the sheet metal parts obtained by forming processes. In its turn, springback is affected by different factors as material properties, tools geometry, process parameters, whose influence is needed to be analysed in order to know how to control them such that the material springback be minimum. In this paper, the experimental analysis concerning the influence of blankholder force and friction conditions on the springback phenomenon in the case of cylindrical deep drawn parts is presented.
STUDY OF DISCHARGE CURRENT AND GAS PRESSURE INFLUENCE ON OPTIMIZED FULLERENE PRODUCTION
CARAMAN MIHAIL, LAZĂR GABRIEL, STAMATE MARIUS, LAZĂR IULIANA
A fullerene production system using the arc discharge technique is presented. The installation was developed in order to optimize the deposition process. The influence of the discharge current and the gas pressure are investigated in order to optimize the fullerene production, in terms of C60/C70 proportion in the carbon soot and of the productivity, compared with other similar results.
THEORETICAL ASPECTS CONCERNING PREDICTION OF GRAVITY FLOW TIME THROUGH ORIFICES OF THE GRANULAR SOLIDS MATERIALS
CĂSĂNDROIU TUDOR, VOICU GHEORGHE, ARSENE IONUŢ
The mathematical models for the gravity flow times of the noncohesive granular materials (with seeds application) are theoretically grounded and developed in this paper. There are proposed concrete models which emphasize the main parameters influencing the flow, as: the bin geometry and the physical characteristics of the granular material. There is done a numerical application which allows us the follow the needed calculus steps, suggesting us the procedure for the elaboration of an calculus software.
CONTRIBUTIONS REGARDING THE INFLUENCE OF BRAN ADDING IN OBTEINING OF DIET BREAD
CIOBANU DOMNICA, LEONTE MIHAI, TULBURE MONICA, MICLĂUŞ LILIANA
By adding the bran and wheat germs additive it was establish the qualitative and nutritional growth of diet bread. The economically solution is an adding a bran in limits a 10-30% of wheat flour. For a normal and efficiency of technological results is necessary: bread yeast 5%, NaCL 2%, germs of wheat 1,5%.
RESEARCHES CONCERNING NUTS DEFORMATION IN THE CASE OF THREADED ASSEMBLY
CRISTEA ION
Nut deformation, which is the main cause of the tightening characteristics loss in a threaded assembly, was analytical and experimental analyzed. A method for the analysis of nut radial deformation was proposed. The performed experiments confirmed the validity of this method and the main conclusion of this paper is that the tightening stress generates a contraction radial deformation on the nut frontal surface, which leads to the increasing of the assembly strength.
STUDY OF TIGHTENING AND BLOCKING CHARACTERISTICS FOR A NEW TYPE OF NUT
CRISTEA ION
The multiple advantages offered by the screw-nut tightening are affected by the possibility that in case of some pulsatory or vibratory loadings the auto-break condition not be satisfied. The present paper refers to a new type of nut, which, by a special construction, offers the possibility of considerable increasing of this condition and also to a series of tests performed in order to practical demonstrate this affirmation.
STRUCTURAL SYNTHESIS OF REVERSE PLANETARY GEAR CAM MECHANISMS
ÆUÆILOVIÆ MILIVOJE
The mechanisms of permanent kinematical structures with two degrees of freedom are widely applied in the technical practice, but there is no structural systematization, which gives an graphical survey of possible kinematical types and which enables the choice of an optimal solution. In the study, there have been identified basic kinematical chains on the basis of which there has been given a systematization of planetary cam gear mechanisms for the generation of periodical (gear) transmitting functions.
ANALYSIS OF FUNCTION APPROXIMATION OF THE WEAR TOOLS FOR TURNING OF THE CAST IRON GG-25 BY NITRIDE CERAMIC CUTTING TOOLS
DAŠIÆ PREDRAG *, NEDIÆ BOGDAN **, JEÈMENICA RATOMIR ***
In this paper is analised the dependence regression between flank wear tools or wear out of belt width on the back surface VB and cutting time t in the form of complex power-exponential regression equation for turning of cast iron GG-25 of cutting tools from nitride ceramic for the different values of the cutting speed v=60, 90 and 120 ?m/min?. Correlation coefficient for given examples of experimental researching is most R=0,998 and mean relative error of experiment is less α=1,25%.
THE MONITORING AND REPORTING OF ENERGY MANAGEMENT IN A COMPANY
HAZI ANETA, HAZI GHEORGHE
In this paper there are presented two components of energy management: monitoring and reporting and computer program for processing data and generated reports. These are applied in a company and are shown results obtained.
DETERMINATION OF CURRENT TRANSFORMERS STATE FROM SUBSTATIONS USING STATISTICAL PROCESSING OF EXPLOITATION DATA
HAZI GHEORGHE, HAZI ANETA
This paper analyses possibility for obtaining of synthetic information about current transformers from substations, using statistical processing of current exploitation data: incidents recorded, results of measures and of tests, derogations, periodically maintenance. Thus, determination of extreme value, of mean value and of square mean deviation can lead to significant conclusions from view point of exploitation activity policy. There are presented results obtained for current transformers in the 400/220/110 kV substations from Moldova.
A WAY OF ASSESSING THE ADMISSIBLE STRESSES IN AREAS WITH CHAMFERED BRACING RIBS OF THE AIR – PRESSURE CYLINDRICAL FRAMES (II)
IATAN RADU
The first part of the article [1] brought in a theoretical study on the way of assessing the state of the admissible stress in a cylindrical structure with radial equidistant chamfered bracing ribs. The inner pressure and the temperature are looked upon as external loads, whereas the connecting ones are considered internal loads (the shearing stress and unitary bending moments). The present article carries out the exemplification of the theoretical results, taking into account an assembly with connecting flanges with chamfered bracing ribs.
CONTRIBUTIONS REGARDING THE USE OF BRAN IN OBTAINING A BAKERY PRODUCT – FERMENTATION CONDITION
LEONTE MIHAI, CIOBANU DOMNICA, MICLĂUŞ LILIANA, TULBURE MONICA
One of the solutions regarding environment cleaning refers to valorising bran, a by- product from the operation of wheat grinding, in obtaining baking products. The research programme is conceived in the centred system, rotary compound of the second degree with four independent variables, using wheat bran in the first technological phase for obtaining dough. An addition of maximum 12% bran could be considered sufficient for achieving the baking products with optimum quality conditions.
STUDY OF AN ELECTRICAL DRIVING SYSTEM WITH INDEPENDENT EXCITATION D.C. MOTOR
LIVINŢI PETRU
This work is presenting en electrical driving system equipped with independent excitation D.C. motor. The mathematical pattern of the electrical driving system has been established and its Simulink pattern has been made. The electrical driving system with D.C, motor has been analysed in the case when the useful resistant torque produced by the load is constant. The variation diagrams of the current and angular speed during the start-up transient duty of the electrical driving system have been drawn out.
RESEARCH REGARDING THE ADDITION OF THE YEAST OVER THE HALF WHEAT BREAD FERMENTATION PROCESS
MICLĂUŞ LILIANA, TULBURE MONICA, CIOBANU DOMNICA, LEONTE MIHAI
Bakery industry has an important place among the production of the food stuff, the bread being a main nutriment used in a daily basis. This research tends to highlight the positive influence of the addition of the bakery yeast over the process of the bread fermentation.
METHODOLOGY OF CONSTRUCTION AND PRODUCTION OF TECHNICAL EQUIPMENT FOR PREPARATION OF PAPER MASS BY APPLICATION OF SOFTWARES PRO ENGINEER AND POWER MILL
MILIÆEVIÆ IVAN *, SLAVKOVIÆ RADOMIR **, GOLUBOVIÆ DRAGAN ***, JUGOVIÆ ZVONIMIR ****
In this work has been described methodology of projecting 3-D models of cutting elements for preparation of paper mass by application of software Pro Engineer. The projection is related with 3-D modeling of plates and conical cutting elements, and of appropriate tools which are used in final technology of preparation of paper mass. Also, there has been described application of software Power Mill for creation of path of cutting tool for production of elements mentioned above on modern CNC milling machines.
THE INFLUENCE OF SOME TECHNOLOGICAL FACTORS ON THE MANUFACTURING PROCESS OF SMOKES MEATS
MIRON DORU NECULAI, NISTOR DENISA, DOSPINESCU ANA-MARIA, GRĂDINARU ANCA
Works proposes the study of the some important technological factors which have influence on the lawsuit of manufacture of fume meats. As factors which can determines a modification of lawsuit of obtaining the finished product, can be enumerates: the time of maturing, the temperature of ebullition and brine concentration. The influence of those proves to be positive in the quality and conservation of fume meats.
THE OPTIMIZATION OF THE PROCESS TO OBTAIN A YOGHOURT WITH FRUIT PULP AND FLAVOUR USING AN EXPERIMENTAL PROGRAM OF FACTORIAL TYPE 33
NISTOR DENISA, MIRON DORU NECULAI, GRĂDINARU ANCA, DOSPINESCU ANA-MARIA
The principal reason for the realization of this study is to establish an optimum field of the principal technological parameters (fruit contents, content of flavour, and leaven concentration) in the case of the process to obtain a yoghourt with fruit pulp and flavour. In the process of sowing of milk with cultures of pure bacteria, a problem major constitutes it the quantity of leaven used. On the way of work we varied 3 factors and we continued the evolutions of 2 feature characteristics: acidity and consistency, prosecutor that, after obtaining these results in laboratory, to remake these date to obtain it from a mathematical model which will be used for optimization.
EXPERIMENTAL DETERMINATION OF CUTTING FORCE BY LONGITUDINAL TURNING OF C60E STEEL
RADOVANOVIÆ MIROSLAV *, DAŠIÆ PREDRAG **, JANKOVIÆ PREDRAG ***
The effects of cutting conditions on the cutting force in the longitudinal turning of C60E steel were experimentally investigated. During experiments, three components of cutting force were measured, the main cutting force, the feed force and the passive force. The width of cut, the thickness of cut, feed, depth of cut and tool cutting-edge angle are found to be affecting force components. The cutting force is influenced not only by cutting conditions but also the cutting edge geometry and the material of workpiece. The influence of the cutting edge geometry and the material of workpiece is not investigate.
WIND GENERATOR REACTIVE POWER COMPENSATION WITH MICROCONTROLLER SOLUTION
ROTAR DAN
Power factor is a measurement of how efficiently a facility uses electrical energy. A high power factor means that electrical capacity is being utilized effectively, while a low power factor indicates poor utilization of electric power. However, this is not to be confused with energy efficiency or conservation that applies only to energy. Improving the efficiency of electrical equipment reduces energy consumption, but does not necessarily improve the power factor. The paper presents a microcontroller power factor compensation for wind energy generator. The main aspects of the power factor compensation with capacitors are discussed and the microcontroller solution is presented.
DATA COMMUNICATION FOR SCADA WIND ENERGY SYSTEM
ROTAR DAN
A SCADA system is a common process automation system which is used to gather data from sensors and instruments located at remote sites and to transmit and display this data at a central site for either control or monitoring purposes. The collected data is usually viewed on one or more SCADA Host computers located at the central or master site. A real world SCADA system can monitor and control hundreds to hundreds of thousands of I/O points. A typical wind energy system SCADA application would be to monitor the energy production of every generator, the quality of electrical energy, and other parameters required by the energy production process. The paper present two solutions for wireless data communications at SCADA wind energy system based on radio modem and cellular network.
MODEL AND METHODOLOGY OF PROJECTING A STRATEGY FOR SUSTAINABLE DEVELOPMENT OF HUMAN SETTLEMENT SYSTEMS (CASE STUDY BACÃU DISTRICT)
STOICA MARICICA
The model and methodology of projecting a development strategy are designed by starting from the concept of sustainable reconstruction resulted as a follow to identification, investigation and diagnosis of ecosystems and projected and built up systems on the territory of Bacãu district.
SUSTAINABLE RECONSTRUCTION – CONCEPT OF DEVELOPMENT FOR HUMAN SETTLEMENTS SYSTEMS (CASE STUDY – BACÃU DISTRICT)
STOICA MARICICA
The author presents her own research made in the inter-disciplinary research project "Research concerning an ecosystemic approach to sustainable development at administrative-territorial level", project financed by National Council of Scientific Research in High Education (CNSIS). The project is ongoing at district level in three phases: in the first phase, year 2004, ecosystems and human habitations were identifed and a diagnosis was made; in the second phase, year 2005, a concept and a development model was elaborated based on the achieved diagnostics; in phase three, year 2006, the elaboration of a sustainable development strategy of the district shall follow, based on the proposed model.
METHODOLOGY TO IMPROVE THE HYDRAULIC FILTER PERFORMANCE FOR ROBOTIC SYSTEM
TOPLICEANU LILIANA
The reliability and maintenance of fluid power systems impose the control of fluid contamination made by hydraulic filters. The standardized multi-pass test is currently the main tool for defining the efficiency of hydraulic filters. But, the test conditions of multi-pass test do not always match sufficiently with actual operating conditions. This may lead to unexpected difference between the filtration efficiency defined in the multi-pass test and the efficiency in real system. This paper presents a test unit used for the testing of hydraulic filters with variable flow. The aim of the research is to test the filtration efficiency under conditions, which are corresponding to real-life working conditions
TWO-STAGE SYSTEM OF ANAEROBIC DIGESTER
TOPLICEANU LILIANA, MOISA MIHAELA
The present paper continues a study about the types of anaerobic digesters for solid wastes compared on technical and biological performance and reliability. The two-stage systems are the most complex, and most expensive of all systems Their greatest advantage lies in the buffering of the organic loading rate taking place in the first stage, allowing a more constant feeding rate of methanogenic second stage. Theses aspects are presented and discussed in the next files.
F.E.M. ANALYSIS UPON THE CHASSIS OF RD 19.256 TRUCK – STATIC LOADING
ZICHIL VALENTIN, SAVIN CARMEN, JUDELE ADRIAN
In now days it is supposed that transportation has to fulfill two major tasks: an increasing volume and weight of the useful transported load with small costs, preserving in the same time the total weight of the transport ( truck and the transported wares). Theses two tasks can be in the same time accomplished on two ways: using for the heavy parts of the truck (engine, gearbox, chassis) new light materials which are in most cases more expensive, or by rebuilding them, through an optimization of the design. Using the numerical analyze program, that operation can be completed in only 30% of the time that is necessary using the traditional methods. In addition with simulation process, the costs are much diminished.
F.E.M. ANALYSIS UPON THE CHASSIS OF RD 19.256 TRUCK – DYNAMIC LOADING
ZICHIL VALENTIN, SAVIN CARMEN, JUDELE ADRIAN
Starting from the consideration that the performances of the present engines for trucks are each day more powerful, with direct implications in the transport speed, the designers has to built chassis according to EURO 4 rules, where the security standards for passive and active safety are very hard to achieve, it is obvious that the dynamic analyze of such a chassis it has to be done. The classical methods of analyze are taking into account a shaft of the transmission of the truck, as the reference shaft. The cinematic chain after the reference shaft is modified based on some simplifying hypothesis with the disadvantage of a lower calculus precision. Using the F.E.M. analyze on dynamic conditions of the chassis, those simplifying hypothesis are eliminated.