Crack initiation and arrest in a pressurized thermal shock test for a model pressure vessel made of VVER-440 reactor pressure vessel steel

A joint pressure vessel integrity research programme involving three partners is being carried out during 1990–1995. The partners are the Central Research Institute of Structural Materials “Prometey” from Russia, IVO International Ltd (IVO) from Finland, and the Technical Research Centre of Finland (VTT). The main objective of the research programme is to increase the reliability of the VVER-440 reactor pressure vessel safety analysis. This is achieved by providing material property data for the VVER-440 pressure vessel steel, and by producing experimental understanding of the crack behaviour in pressurized thermal shock loading for the validation of different fracture assessment methods. The programme is divided into four parts: pressure vessel tests, material characterization, computational fracture analyses, and evaluation of the analysis methods. The testing programme comprises tests on two model pressure vessels with artificial axial outer surface flaws. The first model vessel had circumferential weld seam at the mid-length of the vessel. A special embrittling heat treatment is applied to the vessels before tests to simulate the fracture toughness at the end-of-life condition of a real reactor pressure vessel. The sixth test on the first model led to crack initiation followed by arrest. After the testing phase, material characterization was performed. Comparison of calculated and experimental data generally led to a good correlation, although the work is being continued to resolve the discrepancies between the measured initiation and arrest properties of the material.     

A simplification of code tables in a one-pass PL/M compiler

A two-dimensional table containing code to be output for one binary operation is replaced by an algorithm and two one-dimensional tables. This algorithm constructs the entries of the first table only whey they are needed. The algorithm is in fact an implementation of the thought process used in the hand construction of the first table.     

Modélisation du comportement hygrothermique des parois multicouches: prévision des risques de condensation dans les parois à isolation intérieure et extérieure

Résumé Dans ce travail, nous avons mis en oeuvre une modélisation macroscopique des transferts de chaleur et d'humidité dans les milieux poreux et l'avons appliquée à la prévision des risques de condensation dans les parois à isolation intérieure. Nous avons procédé à une comparaison avec les conclusions que l'on peut tirer d'une démarche simplfiée basée uniquement sur les transferts en phase vapeur en régime permanent. Les calculs numériques ont montré essentiellement que le régime permanent est en fait très long à obtenir en ne sera donc pratiquement jamais observé dans la réalité. La méthode simplifée est, par ailleurs, largement pessimiste en ce qui concerne les risques de condensation. Elle peut être, toutefois, mise en défaut dans le cas de faibles épaisseurs d'isolant et de fortes humidités intérieures.

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Summary In the present work we use a macroscopic model of water and heat transfer in porous bodies and we apply it to the prediction of condensation risks for walls with inside insulation. We make a comparison with the conclusions obtained when using a simple method, based only on steady-water vapour transfer. Numerical calculations showed that the steady state needs a very long time to be obtained, so that it will never be observed in reality. The simple method appears to be very pessimistic about condensation risks, and it can break down for small thickness of insulating material and high interior humidity.

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A disconfirmation bias in the evaluation of arguments.

Two experiments provided evidence for a disconfirmation bias in argument evaluation such that arguments incompatible with prior beliefs are scrutinized longer, subjected to more extensive refutational analyses, and consequently are judged to be weaker than arguments compatible with prior beliefs. The idea that people are unable to evaluate evidence independently of prior beliefs has been documented elsewhere, including in the classic study by C. G. Lord, L. Ross, and M. R. Lepper (see record 1981-05421-001) . The present findings contribute to this literature by specifying the processes by which prior beliefs affect the evaluation of evidence. The authors compare the disconfirmation model to several other models of how prior beliefs influence current judgments and present data that provide support for the disconfirmation model. Results indicate that whether a person's prior belief is accompanied by emotional conviction affects the magnitude and form of the disconfirmation bias. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optimization of metallurgical variables in fracture prevention

The effect of metallurgical variables on the two most important crack growth mechanisms - stable crack growth by environmentally assisted cyclic crack growth and unstable crack growth by cleavage - in light water reactor pressure vessel steels is evaluated. The analyses are based on micromechanisms of fracture and sensitivity analysis, when applicable. Metallurgical variables considered are non-metallic inclusions and carbides as well as other parameters through their effects on yield strength and other mechanical properties.     

A Broadband Quadrature-Modulator with Integrated Baluns

A broadband direct-conversion quadrature-modulator has been implemented in 0.8 m SiGe with integrated baluns in its RF-signal paths. Measured performance includes IRR-values at better than –40 dBc in 0.75–3.6 GHz with output power levels in excess of –20 dBm. For this performance circuit draws 46 mA from a single 2.5 V supply.Esa Tiiliharju was born in Rovaniemi, Finland, in 1966. He received the M.Sc. degree in Information Technology in 1995, and the Lic.Tech degree in electrical engineering in 1998, both from Helsinki University of Technology, Finland.From 1996 to July 1997 he was employed as assistant at Helsinki University of Technology. He has been holding a position of a research assistant from 1997, and he is currently working towards the Ph.D. degree in the Electronic Circuit Design Laboratory at Helsinki University of Technology.His research interests include the design of integrated low-power circuits for portable telecommunication applications. He has designed and measured several integrated circuits for this application area. He is author or co-author for several international refereed conference and journal publications on analog integrated circuits.Kari A.I. Halonen was born in Helsinki, Finland, on May 23, 1958. He received the M.Sc. degree in electrical engineering from the Helsinki University of Technology (HUT) in 1982 and the Ph.D. degree in electrical engineering from the Katholieke Universiteit Leuven, Heverlee, Belgium, in 1987.From 1982 to 1984, he was with HUT as an Assistant and with the Technical Research Center of Finland as a Research Assistant. From 1984 to 1987, he was a Research Assistant with the E.S.A.T. Laboratory, Katholieke Universiteit Leuven, with a temporary grant from the Academy of Finland. Since 1988, he has been with the Electronic Circuit Design Laboratory, HUT, as a Senior Assistant from 1988 to 1990, and as the Director of the Integrated Circuit Design Unit of the Microelectronics Center from 1990 to 1993. He was on leave of absence during the academic year 1992–1993, acting as Research and Development Manager with Fincitec Inc., Finland. From 1993 to 1996, he was an Associate Professor, and since 1997, he has been a full Professor with the Faculty of Electrical Engineering and Telecommunications, HUT. He became the Head of Electronic Circuit Design Laboratory year 1998. He was the Technical Program Committee Chairman for the European Solid-State Circuits Conference in 2000. He is the author or coauthor of over 150 international and national conference and journal publications on analog integrated circuits, and holds several patents on analog integrated circuits. His research interests are in CMOS and BiCMOS analog integrated circuits, particularly for telecommunication applications.Dr. Halonen was an Associate Editor of the IEEE Transactions on Circuits and Systems–Part I: Fundamental Theory and Applications from 1997 to 1999. He has been a Guest Editor for the IEEE Journal of Solid-State Circuits. He received the BeatriceWinner Award from the IEEE International Solid-State Circuits Conference in 2002.     

Toward improved catalytic low-temperature NOx removal in diesel-powered vehicles

The potential of different catalytic after treatment techniques to meet future diesel emission standards, which are strongly shifted toward urban driving conditions including cold start, are critically discussed in this Account and evaluated for their suitability for commercial applications. The dominating techniques in this field are NO(x) storage, urea-selective catalytic reduction (SCR), and HC-SCR. Each of these techniques have significant disadvantages such as sulfur sensitiveness and regeneration requirements of NO(x)-storage materials, infrastructure issues and formation of ammonium nitrate (at low temperatures) for urea-SCR, and low-temperature activity of HC-SCR catalysts. Ways to overcome these disadvantages in commercial applications may involve optimized regeneration strategies, reactor modifications, flow reversal, closed-loop NO(x) feedback systems, nonthermal plasma, and/or hydrogen-assisted catalyses, etc.     

Titanium precatalysts bearing N-substituted β-amino alcohols for 1-hexene polymerization: The effect of steric crowding

A series of titanium-based non-metallocene precatalysts [2-(2,6-dialkylphenylamino)-1-phenylethoxy TiCl₂ were prepared by reacting lithium salts of the corresponding amino alcohols with TiCl₄(THF)₂. Upon activation with methylaluminoxane (MAO), these precatalysts polymerized 1-hexene in isotactic manner. The catalyst activity and polymer properties depended on the steric features in the ortho positions of the aniline moiety of the ligands. As the bulkiness of the alkyl group in ortho positions of the aniline moiety increased, the catalyst showed better activity with high molecular weight and greater tacticity control. For 1-hexene polymerization, precatalyst 1ATiCl₂ showed activity of 3.05 kg of PH/mol-Ti.h at room temperature and the resulting polyhexene had molecular weight of 403,600 (M_w/M_n=1.40) with 80% isotacticity (mmmm). The dibenzylic titanium complexes 1ATi(CH₂Ph)₂ and 3ATi(CH₂Ph)₂, upon activation with MAO or Ph₃CB(C₆F₅)₄, showed relatively lower activities towards 1-hexene polymerization, yielding polymers of lower molecular weights but with narrow molecular weight distribution.