Annals of „Constantin Brâncuşi” University of Târgu Jiu ENGINEERING SERIES

4

Authors: S.S.Stoyanova

There is proposed an approximate formula to determine the induction in pneumatic interspace of not branching magnetic circuit with constant magnet. The formula can be used in case when it is not dispose of the constant magnet histeresis curve, but only the residual induction and the coercive magnetic intensity are known.

8

Authors: Mihai Cruceru

In drawing up the balance sheet for thermal power boilers energy, specific heat loss through convection and radiation to the environment are calculated by statistical relationship or are chosen from diagrams depending on boiler load. If these values are close to reality for new or upgraded boilers, to boilers whose isolation was not maintained the values chosen are far undersized. By using thermography one can calculate the insulation outer surface temperature, the heat flux using specific relations and the actual loss of heat by convection and radiation.

10

Authors: CĂPĂŢÎNĂ Camelia, ŞCHIOPU Emil Cătălin

Dangerous wastes jeopardize human health, by short or long term exposure. In the paper it is presented the capitalization by incorporation in the vitreous matrix of some galvanic wastes with nickel content and obtaining some bottles that can be used in an industrial manner. Melting proofs was realized at the temperature of 610°C, for 30 minutes, and their cooling once with the oven. To the tests that resulted have been determined the hydrolytic stability through the conductometric method. The experimental results show a good chemical stability of the bottles obtained from wastes.

12

Authors: S. GROUDEV, I. SPASOVA, M. NICOLOVA

acid drainage waters generated in the uranium deposit curilo, bulgaria, were treated by means of a passive system consisting of two constructed wetlands connected in a series. The waters had a ph in the range of about 2 – 4 and were heavily polluted by radionuclides, several heavy metals, arsenic and sulphates. The first wetland was characterized by a subsurface water flow, a very dense water and emergent vegetation and a large anaerobic zone in which different sulphate-reducing bacteria and some metabolically interdependent species were the prevalent microorganisms. The second wetland was a predominantly aerobic system due to the cascade-type construction of its bottom and the surface water flow. The water flow through the wetlands varied in the range of about 0.2 – 0.75 l/s, reflecting total residence times of about 90 to 25 hours. An efficient removal of pollutants was achieved by this system during the different climatic seasons, even during the cold winter months at water temperatures close to the freezing point.

7

Authors: O.T. Mewomo, B.A. Popoola

The notion of approximate ultraamenability in Banach algebras is introduced. General theory is developed for this notion. In particular, we show that the projective tensor product between the Banach algebra A and B (A B ⊗ˆ ) is not approximately ultra-amenable whenever A is not approximately ultra-amenable and B admits a nonzero character.

8

Authors: Sevasti Mitsi, Iulian Popescu, Liliana Luca

In the present paper the structural analysis of the Assur group of class 4 and order 2 (tetrad) is investigated. Beginning from the tetrad with revolute joints and replacing successively the revolute joint by prismatic joint, 64 kinds of tetrad are generated. The structural analysis of these kinds leads to 24 kinematic models. From these are removed the models that degenerate in four family mechanisms or mechanism with apparent family.

8

Authors: Marius Bîzgă, Onisifor Olaru, Emil Viorel Mihai

The SO2 emissions are one of the biggest problems for coal fired thermal power plants. As a result of stringent environmental protection regulations regarding SO2 emissions, SO2 must be removed from flue gases. This paper reveals technical solutions for controlling WFGD installations applied at Rovinari PP.

9

Authors: Grofu Florin, Cercel Constantin

There are many applications where it is necessary to keep humidity within certain predefined limits. Maintaining a certain level of moisture is needed from the comfort homes, special rooms for drying certain products, keeping in good conditions of old manuscripts or meteorites collectors. Typically these applications require reducing humidity to a predetermined level.

9

Authors: ANASTASIADIS P., G. METAXAS

Designers of buildings and their service systems play a key role within the building sector. Consciously or not they regularly choose between alternatives with a greater, or lesser, environmental impact. Informed choices to be made, it is essential that these professionals have insight into the relative environmental impact of the options open to them. Reliable details on the environmental effects of building materials and certain technical operations are not freely available. Up to now the environmental profiles of individual products and processes have mainly been identified by means of Life Cycle Analysis (LCA) studies, which map out the environmental effects of a particular material, from extraction through to production, use demolition and recycling. There is already substantial agreement that LCA is not suitable for comparing choices in the design process of buildings, moreover, most building products have not yet been investigated in this way. Further, these studies do not tell us how to evaluate one kind of environmental impact against another. Life cycle management is a new practical integrated and systematic approach to minimize the environmental and social-economic burdens associated with a product over its entire life cycle and value chain. Key words

10

Authors: Goce Stefanov

The paper are given the results of the comparison between the topology of full bridge and half bridge converter with serial resonant circuit, obtained by computer simulation. Results of simulations should show the differences in the design of full bridge and half bridge converters burdened with serial resonant circuit. One of the primary applications of configuration to the bridge converter with serial resonant circuit is mode of induction device for heating the metals. For defined output power and frequency of converter with serial resonant load the simulations are made in the program PowerSim, [10]. On the end of the paper are given the results from the simulation project program of semikron, Semisiel [11], for one topology on full bridge converter with IGBT module.

10

Authors: K.P.R.Rao, G.Ravi Babu, V.C.C.Raju

In this paper, we obtain two common fixed point theorems , one for two pairs of single and setvalued mappings and another for four set-valued mappings satisfying implicit contractive type conditions. 2000 Mathematics Subject Classification : 47H10 , 54H25

10

Authors: Adrian Runceanu, Marian Popescu, Mihaela Runceanu

E-learning can be a very effective tool for organizations wishing to develop staff or provide training in new products and processes. The Information and Communication Technology can be used as a resource, a resource that provides access point for information as well as real world requirements. This paper gives information about some free software which helps to create online courses and helps in teaching-learning process.

10

Authors: Mădălina Roxana Buneci

A coupled cell system is a network of dynamical systems (cells), represented by a directed graph that indicates how cells are coupled and which cells are equivalent. Golubitsky and Stewart [1-3] introduced a formal framework for obtaining information about system dynamics from the topology of the graph of couplings. The purpose of this paper is to present how Maple environment can be used for rapid development of procedures implementing this model (multiple arrows and self-couplings are allowed).

11

Authors: Šusteková D.

In this article there is described a basic concept of artificial intelligence and the main parts of expert systems (designed and created myself) especially – the inference engine designed using decision according to criteria. There are results of described expert system as Failure evaluation the same types of aircrafts at operators, Field reliability evaluation of several types of aircraft and Final evaluation according all of criteria – the weight of criteria is the same and Final evaluation according all of criteria, where the weight of criteria - flying hours costs - is changed.

11

Authors: Valeriu PLEŞEA, Marius Eremia VLAICU POPA

In the present conditions from Romania, the starting of economical reorganization process proved that great sectors and enterprises can not be closed in a short time. None the less, the number of closed objectives and discharged personnel until now creates big controversies, being a major problem hard to surmount. The effects of the reorganization in the mining industry field being much more acute, within this paper are presented, in an original way of study and analyze, the options of economical rehabilitation and working places development for the mining affected areas.

6

Authors: Constantin Tricikov, Machidon Alina

this paper presents some aspects about the different laws used to control the speed of the electric engines powered by a variable frequency power supply

8

Authors: Panagiotis SINIOROS, Mihai CRUCERU, Bogdan DIACONU

The Romanian Black Sea coast is the summer vacancy destination for approximately 2.500.000 tourists. In the summer months, the temperature reaches often 35 degrees Celsius. In such circumstances, the local authority interest for offering services at high standards is obvious. Since the cost for air conditioning using the conventional methods is very high, in the context of sustainable development, renewable sources of energy have been sought. The paper analyses the technical possibilities of using the seawater as source of cold energy and absorption system using solar thermal energy. The HVAC systems based on renewable energy are compared to conventional vapor compression system from the efficiency viewpoint

10

Authors: Bogdan Diaconu, Valentin Paliţă, Mihai Cruceru, Cristinel Racoceanu, Adriana Foanene

Wilson plot technique is being widely used for determining experimentally the convection heat transfer coefficient and developing convection heat transfer correlations for various flow and geometrical configurations. Wilson plot method is simple enough to be applied in laboratory practices for university and doctoral level students. Its features render it adequate to be included in university engineering coursed.

16

Authors: Tencho Kairakov, Atanas Smilianov, Tsvetan Damyanov, Violeta Ivanova

The concepts and principles have been described, which are the basis for measuring the quality and the ash content of coal, mined at the “Maritsa East” EAD and supplied to the main consumers – Thermal Power Plant 1, Thermal Power Plant 2, Thermal Power Plant 3 and the Briquettemanufacturing Plant.