Volume 3, No. 14 (2008)
Articles
A STUDY OF SHAPE AND DIMENSIONAL ACCURACY OF THE CYLINDRICAL DEEP-DRAWN PARTS
AXINTE C., IORDACHE M.
In sheet metal forming operation, springback of the part during unloading phase largely determines whether the part conforms to the design dimensions and tolerances. This work deals with the accuracy of the cylindrical parts obtained by deep-drawing process.
ANALYSIS AND DETERMINATION OF OPTIMAL DEPTH OF SETTING PIPELINE WITH COLD WATER
BAJMAK M. ŠEFIK
In system of centralized supply of coolant energy (cold water) important place takes pipeline network of coolant energy, by which cooled water is delivered to consumer (air condition). Transport of cooled water is usually performed by two-pipe system. As experiments have found, depth of setting pipelines for cooled water is a minimal value of total year investiture costs, loses of heat and costs of pumping cooling water.
ANALYSIS AND CALCULATION OF NEEDED PARAMETERS OF AIR FOR CONDITIONING AND VENTILATION OF ROOM FOR CERTAIN USE
BAJMAK M. ŠEFIK(1), VEIS ŠERIFI(2)
Ventilation of the air is necessary due to complacence of human need for air, for dilution of polluted air, amount of fresh air which depends from allowed level of harmful components in room air (polluting component can be , which is produced by human breathing, technological process), for enabling air circulation in a room, which is the one of components for comfort conditions. To satisfy human needs for fresh air, it is necessary new amount of outer air. Relevant moment in determination of needed amount of fresh air is calculation of dilution of harmful component (for example, and human breath) or appeared in technological process. Based on such determined amount of fresh air we can approach to a choice of system for ventilation and conditioning of certain work recycled or technological rooms or establishments. In that context in paper is shown calculation methodology of air amount for ventilation of static and variable sources of appearance harmful components in work and manufacturing rooms.
RECENT EVOLUTION OF FOREIGN DIRECT INVESTMENT IN DEVELOPING COUNTRIES
DROB CATALIN
This study aims is to present the main aspects regarding evolution of foreign direct investment in developing countries. In the last period, the level of the foreign direct investment inflows to and outflows from developing countries recorded an ascendant course, especially in certain regions (South, East and South-East Asia, Latin America and the Caribbean and South-East Europe and the CIS) and countries (China, Brazil, Mexico, Singapore, Czech Republic, Poland, Chile, Korea etc.).
EVOLUTION OF CAPITAL MARKET IN ROMANIA
DROB CATALIN
This study aims is to present the main aspects regarding the evolution of capital market in Romania. The main component of capital market in Romania is Bucharest Stock Exchange. The Bucharest Stock Exchange role is to provide a marketplace for securities transactions. With the exception of 2008, recent evolution of the capital market in Romania was very good and the perspectives are also positive.
INVESTIGATION OF TECHNOLOGICAL PARAMETERS INFLUENCE ON THE DYNAMICS OF TEMPERATURE-HUMIDITY REGIME IN EGG PRODUCTS SPRAY DRYER THROUGH A MODEL
EVSTATIEVA NADEZHDA
The dynamics of egg melange temperature and humidity variation significantly affects the egg powder quality. It depends on a number of interrelated parameters. Such are the drying agent temperature and humidity, the mélange temperature and feed rate, the design parameters and others. The research purpose is the assessment through a model of the technological parameters influence on the temperature and humidity variation of the mélange and drying agent as a function of time. Computer software has been used for this purpose. It is based on a model, describing the drying process in an egg spray dryer. Methodology for the research has been developed. The results of this investigation are represented graphically. The level of certain parameters influence has been estimated.
RESEARCHES CONCERNING THE IMPACT OF A HIGH SPEED JET ON A VARIABLE ANGLE
FLORESCU IULIAN, MOSNEGUTU EMILIAN, NEDELCU DRAGOS
In the present paper the depths and the forces per unit width that the rigid surface exerts against the jet are calculated. The FLUENT simulations are presented too.
CLASSIFYING BAYESIAN NETWORKS BY ESSENTIAL GRAPHS
GARRIDO ANGEL
We improve the efficiency of Bayesian Network learning procedures, by selecting as search space the equivalence classes of Directed Acyclic Graphs (DAGs), and from them an essential graph as representative of each class. For this purpose, we describe some results, and observe the asymptotical behaviour of its respective ratios.
ESSENTIAL GRAPH AS VERY EFFICIENT TOOLS
GARRIDO ANGEL
Bayesian Nets (BNs, in abridged expression) represent joint probability distributions (JPDs). We says that two BNs are equivalent (denoted by C), if both represent the same JPD. Now, we can see some useful characterizations of the equivalence among BNs, and the usefulness of Essential Graphs (EGs) as representatives of equivalence classes of BNs, in AI; for instance, learning BNs.
STUDY ON THE EARING MINIMIZATION IN THE CUP DRAWING PROCESS
IORDACHE M., AXINTE C.
The blanks are anisotropic; their mechanical characteristics are different in the rolling direction unlike other directions which are not parallel to it. Anisotropy favors the appearance of earing in the cup drawing process, which constitutes a fabrication flaw of the piece. This paper presents the optimizing of the initial shape of the blank in order to minimize the earing in the cup drawing process. The experimental results are compared to the results obtained through simulation using the finite element method (FEM). The simulation took place with the help of the program ABAQUS/Explicit, v6.5.
OSCILLATING SOLUTIONS OF RICCATI’S EQUATION
MILENA LEKIC(1), STANA CVEJIC(1), DRAGAN DIMITROVSKI(2)
In this work, we determined a general solution without looking for the particular integrals for the Riccati’s equation in which the coefficients a(x), b(x) and c(x) are analytic functions on the semi-axis [0, +?) and where a(x) does not have real zeros. We did this, first, by transforming the equation into its canonical form and then by applying the iteration sequence method. At the end we determined some conditions which are sufficient in order to obtain oscillating solution.
WEAR EROSION-CORROSION STUDY OF CARBIDE SEAT AND CERAMIC BALL IN VALVE OF CRUDE PETROLEUM EXTRACTION PUMP
NEGRIU R.M., DRAGOI D. D., BESLEAGA CR, SARLEA I
This paper describes a study case of the erosion-corrosion wear for ball—valve pump, which works in a crude petroleum fluid. The experimental results were used to identify the optimal material for ball and seat of valve pump. The synergic effect of erosion and corrosion rate was observed for carbide and ceramic composites. The relations for the erosion rate and corrosion can be used to construct wear maps for ball and seat materials working in petroleum fluids.
LA PARTICIPATION DES FEMMES AUX STRUCTURES DE PRISE DE DECISION COMME FACTEUR D’INTEGRATION SOCIOECONOMIQUE : CAS DES FEMMES DE LA COMMUNE DE BUYO (SUD-OUEST DE LA COTE D’IVOIRE)
N'TAIN YEMOU JEANNE(1), NEDEFF VALENTIN(2), PANAINTE MIRELA(2), MACARESCU BOGDAN(2), MOSNEGUTU EMILIAN(2)
Partout le monde entier et à tous les niveaux de la prise de décision, les femmes sont sous-représentées. On retrouve partout une donnée commune : la participation des femmes n’est jamais paritaire. Cependant, en termes de qualité de la participation des femmes aux processus de prises de décisions, cette étude montre que la participation des femmes aux niveaux spécifiques apporte un changement significatif dans les processus de développement de leur localité.
ASSESSMENTS CONCERNING THE DURABILITY COMPUTATION IN CASE OF THICK WALL CYLINDERS
PINTILIE GHEORGHE, ALBUT AURELIAN
The durability calculation represents an important stage in designing of the thick wall cylinders, due to avoid the fatigue failure during the operating process. This paper presents aspects regarding the stress state from cylinders loaded with high pressure and it is indicated the important role of stress behaviors in initiation and propagation of the fatigue crack. The paper presents a case study, analyzed using the NASGRO 5.0 simulation software, hereby is determined the critical length of the fatigue crack and the conformable number of cycles.
ASPECTS REGARDING NUMERICAL CALCULATION OF THE STRESS INTENSITY FACTOR FOR COMPLEX LOADS
PINTILIE GHEORGHE, ALBUT AURELIAN
In this paper are presented theoretical aspects regarding calculation of the stress intensity factor in case of superposed loads. For exemplification are presented the equations used in case of the plate with central crack and for the plate with marginal crack, for which numerical simulation are carried out. In the end of the paper are presented the variations of the stress intensity factor, , function to the number of cycles, N, and the crack length, a.
AN APPROACH TO DESIGN OF APPLICATION FOR EXAMS REGISTRATION BY WEB
SRÐAN JERINIC(1), ZORAN NIKOLIC(2)
Real expansion of Internet technologies and services, as well as communication and computer systems, has resulted in doubling the amount of information available on the Web on a yearly basis, thus the period we live in named “days of accelerated changes”. An important segment of this development is Internet programming that encompasses knowing Internet technologies, information technologies and various programming languages, then having experience in programming and managing data bases as well as mastering marketing and design. Thus, the introduction to this paper offers a short overview of the basic contemporary Internet technologies in the extent that allows gaining the right image of the complexity of Web application design. Due to the information overload, concerning all aspects of life and work, functioning of the modern information systems cannot be imagined without data bases, which makes design of three tier Web applications a special challenge to programmers. An example of such an application is registering for exams by Web, which is presented in this paper. By putting this application into operation, a contribution is given to more effective functioning of a students’ service in sense of exams scheduling and registering as well as results announcing and digital documents and certificates issuing.
ELECTRONIC SYSTEM FOR CONTROL OF EGG-PRODUCT SPRAY DRYER
TABAKOV STEFAN(1), EVSTATIEVA NADEZHDA(2), MIHAILOV NIKOLAY(2)
Spray dryer features have been analysed in this paper, and criteria for drying process kinetic curves analysis have been grounded. An algorithm for the performance of an electronic system which controls the spray dryer on the basis of the process model has been suggested. An algorithm of a subprogram for the drying process kinetic curves assessment on the basis of particular assessment criteria has been presented. An algorithm for the specialised controller performance has been produced. A structural scheme of a spray drying control electronic system has been developed. It is composed of a personal computer simulating the drying process through a model, and a specialised controller collecting data about the process parameters, and controlling the actuating units.