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Found 6278 publications

Comprehensive investigation of the corrosion state of the heat exchanger tubes of steam generators

No authors available

Publication Name: European Corrosion Congress 2009, EUROCORR 2009

Publication Date: 2009-12-01

Volume: 2

Issue:

Page Range: 1212-1220

Description:

Evaluating the water chemistry in the primary circuit and the effect of chemical decontamination of the heat exchanger tubes performed by the AP-CITROX procedure at Paks NPP (Hungary), a project dealing with the comprehensive investigation of the general corrosion state of the steam generators (SGs) has been initiated. Owing to the fact that there is no investigation method available for the in-situ monitoring of the inner surfaces of heat exchanger tubes, a research program based on sampling as well as on ex-situ electrochemical and surface analytical measurements were developed and elaborated. In the time period of 2000-2008 - within the frame of the above project - 45 stainless steel specimens, cut out from various locations of the steam generators of the Paks NPP were investigated. Besides to the corrosion characteristics (corrosion rate, thickness and chemical composition of the protective oxide-layer) surface properties (morphology, chemical and phase compositions) of the passive layer formed on the inner surface of above heat exchanger tubes were studied, too. The passivity of the inside surface of the stainless steel specimens was measured by voltammetry, the morphology, chemical and phase compositions of the oxide layer formed on the surface were analyzed by SEM-EDX, XRD and CEMS methods. The great number of experimental results allowed us to develop an electronic database which involves the results of the above corrosion experiments, and also some special characteristics of the tubes (e.g. location in the SGs, surface pretreatment by decontamination, if any, etc). Evaluating the main relations among these parameters may contribute to the identification of important processes affecting the corrosion state of steam generators, and highly decisive concerning a life time prolongation project of VVER-type nuclear reactors. In the present work we provide a brief overview on these experiments, some characteristic results, the database developed, as well as some novel findings.

Open Access: No

DOI: DOI not available

Concept of an atomic beam probe diagnostic on COMPASS tokamak

M. Berta G. Anda D. Dunai M. Aradi G. Veres S. Zoletnik A. Bencze

Publication Name: 36th Eps Conference on Plasma Physics 2009 Eps 2009 Europhysics Conference Abstracts

Publication Date: 2009-12-01

Volume: 33 E2

Issue: Unknown

Page Range: 1399-1402

Description:

No description provided

Open Access: Yes

DOI: DOI not available

Robot cooperation without explicit communication by fuzzy signatures and decision trees

No authors available

Publication Name: 2009 International Fuzzy Systems Association World Congress and 2009 European Society for Fuzzy Logic and Technology Conference, IFSA-EUSFLAT 2009 - Proceedings

Publication Date: 2009-12-01

Volume:

Issue:

Page Range: 1468-1473

Description:

This paper presents a novel action selection method for multi robot task sharing problem. Two autonomous mobile robots try to cooperate for push a box to a goal position. Both robots equipped with object and goal sensing, but do not have explicit communication ability. We explore the use of fuzzy signatures and decision making system to intention guessing and efficient action selection. Virtual reality simulation is used to build and test our proposed algorithm.

Open Access: No

DOI: DOI not available

Solution for fuzzy road transport traveling salesman problem using eugenic bacterial memetic algorithm

No authors available

Publication Name: 2009 International Fuzzy Systems Association World Congress and 2009 European Society for Fuzzy Logic and Technology Conference, IFSA-EUSFLAT 2009 - Proceedings

Publication Date: 2009-12-01

Volume:

Issue:

Page Range: 1667-1672

Description:

The aim of the Traveling Salesman Problem (TSP) is to find the cheapest way of visiting all elements in a given set of cities and returning to the starting point. In solutions presented in the literature costs of travel between nodes (cities) are based on Euclidean distances, the problem is symmetric and the costs are constant. In this paper a novel construction and formulation of the TSP is presented in which the requirements and features of practical application in road transportation and supply chains are taken into consideration. Computational results are presented as well.

Open Access: No

DOI: DOI not available

Behaviour of transdanubian clay under unloading and reloading

Edina Koch

Publication Name: Proceedings of the 17th International Conference on Soil Mechanics and Geotechnical Engineering the Academia and Practice of Geotechnical Engineering

Publication Date: 2009-12-01

Volume: 1

Issue: Unknown

Page Range: 463-465

Description:

In recent years, in the field of geotechnical design, software based on FEM has come to the front. Advanced computer programs make it possible to use more developed soil models besides the most current elastic-plastic Mohr-Coulomb model. By using these computer programs, nonlinear behaviour of the soil can be followed better, even in the case of more complicated load events. Among the constitutive models incorporated in the commercial software the Hardening Soil Model (HS) and Soft Soil Model (SS) are the most promising ones. Observations and experience gained in tunnel construction, deep open excavation or preloaded embankment prove that with these soil models reality can be followed more accurately, especially in cases where unloading and reloading are present. In order to produce the software input parameters, in case of more complicated soil model, more demanding laboratory tests are needed. In case of HS model one of the basic demands is to determine the power for stress-level dependency of stiffness (m), tangent stiffness for primary oedometer loading (E oed ref) and unloading/reloading stiffness (E ur ref). The paper focuses on the behaviour of transdanubian clay common in Hungary. Sampling, laboratory investigations and evaluation aimed to determine the input parameters for the HS are described. Results based on a number of oedometric tests accomplished with unloading and reloading proved to be adequate for the computational purposes. © 2009 IOS Press.

Open Access: Yes

DOI: 10.3233/978-1-60750-031-5-463

Chemical decontamination of steam generators used in nuclear power plants II. Comprehensive investigation of the efficiency of used in nuclear power plants II. Comprehensive investigation of the efficiency of chemical decontamination technologies

Baradlai Pal Horváthné Deák Emese Szeiler Gábor Borszeki Janos Andrea Szabó Nagy Németh Zoltán Varga Kálmán Halmos Pal Varga Istvan Radó Krisztián Patek Gábor Schunk János

Publication Name: Korrozios Figyelo

Publication Date: 2009-12-01

Volume: 49

Issue: 5

Page Range: 86-94

Description:

Our earlier publications have been focused on detailed explanation of the effects of the applied AP-CITROX chemical decontamination technology on the corrosion state and surface morphology of heat exchanger tubes of steam generators (SG). These studies have revealed that the industrial application of the decontamination technology results in the inhomogeneous dissolution of stainless steel surface, leading to the formation of oxide layer with undesired chemical composition and structure which exhibits potentially greater mobility in the primary coolant. Laboratory examinations have provided an independent verification of the formation of the so called "hybrid" structure. The first part of our three-part series has presented some selected findings on the corrosion and surface chemical effects of the AP-CITROX technology as well as the fundamental issues of the technology development. Present paper deals with the efficiency (mass transport and decontamination characteristics) of the novel chemical decontamination technologies elaborated for the treatment of the inner surface of SGs and regenerative heat exchangers of the water purification system No. 1. The third part of our series is scheduled to highlight some results obtained by laboratorial analysis of the effects of the two novel technologies on the corrosion state as well as on the structure and composition of surface oxide layer. Determining the radioactivity of specified nuclides in the solutions used for decontamination, important conclusions on the efficiency of the main technological steps as well as on the distribution of radionuclides in the depth of treated surface can be drawn.

Open Access: Yes

DOI: DOI not available

Quasi optimization of fuzzy neural networks

No authors available

Publication Name: 10th International Symposium of Hungarian Researchers on Computational Intelligence and Informatics, CINTI 2009

Publication Date: 2009-12-01

Volume:

Issue:

Page Range: 303-314

Description:

The fuzzy flip-flop based multilayer perceptron, named Fuzzy Neural Network, FNN is proposed for function approximation. In recent years much effort has been made for the development of a special kind of bacterial memetic algorithm for optimization and training of the fuzzy neural network parameters. In this approach the FNN parameters have been encoded in a chromosome and participate in the bacterial mutation cycle. The quasi optimized FNN's performance based on various fuzzy flip-flop types has been examined with a series of multidimensional input functions.

Open Access: No

DOI: DOI not available

Direct preisach hysteresis model for finite element analysis of magnetic fields

Miklós Kuczmann Daniel Marcsa

Publication Name: Przeglad Elektrotechniczny

Publication Date: 2009-12-01

Volume: 85

Issue: 12

Page Range: 114-117

Description:

This paper deals with the numerical analysis of the Problem No. 32 of the TEAM Workshops. This is a three-limbed ferromagnetic core with pick up coils, which is a test bench for validation of numerical analysis with hysteresis. The numerical procedure is based on the magnetic field computation taking the hysteresis into account. The scalar Preisach model is integrated into a finite element analysis. The hysteretic nonlinearity is handled by the fixed point iterative technique. The results are validated by comparison with the experiments.

Open Access: Yes

DOI: DOI not available

Comprehensive investigation of the corrosion state of the heat exchanger tubes of steam generators

Krisztián Radó Gábor Patek Bernadett Baja N. A. Szabó Varga Kálmán Zoltán Németh Schunk János Z. Homonnay E. Kuzmann

Publication Name: European Corrosion Congress 2009 Eurocorr 2009

Publication Date: 2009-12-01

Volume: 2

Issue: Unknown

Page Range: 1212-1220

Description:

Evaluating the water chemistry in the primary circuit and the effect of chemical decontamination of the heat exchanger tubes performed by the AP-CITROX procedure at Paks NPP (Hungary), a project dealing with the comprehensive investigation of the general corrosion state of the steam generators (SGs) has been initiated. Owing to the fact that there is no investigation method available for the in-situ monitoring of the inner surfaces of heat exchanger tubes, a research program based on sampling as well as on ex-situ electrochemical and surface analytical measurements were developed and elaborated. In the time period of 2000-2008 - within the frame of the above project - 45 stainless steel specimens, cut out from various locations of the steam generators of the Paks NPP were investigated. Besides to the corrosion characteristics (corrosion rate, thickness and chemical composition of the protective oxide-layer) surface properties (morphology, chemical and phase compositions) of the passive layer formed on the inner surface of above heat exchanger tubes were studied, too. The passivity of the inside surface of the stainless steel specimens was measured by voltammetry, the morphology, chemical and phase compositions of the oxide layer formed on the surface were analyzed by SEM-EDX, XRD and CEMS methods. The great number of experimental results allowed us to develop an electronic database which involves the results of the above corrosion experiments, and also some special characteristics of the tubes (e.g. location in the SGs, surface pretreatment by decontamination, if any, etc). Evaluating the main relations among these parameters may contribute to the identification of important processes affecting the corrosion state of steam generators, and highly decisive concerning a life time prolongation project of VVER-type nuclear reactors. In the present work we provide a brief overview on these experiments, some characteristic results, the database developed, as well as some novel findings.

Open Access: Yes

DOI: DOI not available