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.     

Octet error probability analysis of ADSL–DMT codewords

This paper presents an analytical investigation of the octet error probability of ADSL codewords under the impact of white Gaussian noise. It is shown that the assumption of independent bit errors which can be found in the literature is invalid in this case. Instead, as a novel method, bitgroups from DMT subcarriers contributing to a particular octet are analyzed. Typical bitgroup types are discussed with regard to their error probability. Finally, proposals for applying these results in optimized system solutions are derived.     

Carbon hard masks for etching sub-90 nm structures

Carbon hard mask structures have been used to etch a variety of materials typically used in sub 90 nm DRAM manufacture. The results indicate that carbon hard masks can be used very effectively to structure oxide, nitride and metal films giving the CD performance required for the technologies being investigated.     

Simulation based analysis of secondary effects on solder fatigue

Secondary effects on thermal fatigue of solder joints, which frequently have been neglected, were studied by means of the finite element method (FEM). Based on a semi-empirical approach to predict fatigue life by evaluating the cyclic accumulated equivalent creep strain or energy density, effects of organic boards intrinsic properties on solder joint fatigue were investigated. Aspects of more realistic FR-4 board modelling were studied, in particular concerning its in-plane anisotropy and intrinsic warpage behaviour. Intrinsic board warpage was measured on test board level as well as for boards from series production. High intrinsic warpage was in particular found for several test boards. The effects for the worst case scenario observed so far were analysed for both first level and second level interconnects. The change in predicted fatigue life varied between 30% and 500%, the latter most critical effects were found at large QFN components. Another secondary effect studied was to include the frequently neglected interfacial intermetallics into FEM. It turned out that for components with relatively large standoff like LFBGAs the effects were actually negligible, but for the highly miniaturized components like chip resistors CR0201 they are the decisive factor.     

Spannungen im Stab,Richtkraft und Antriebsmoment beim Richten von Rundstäben in Zwei-Walzen-Richtmaschinen

Biegerichten in Schrägwalzen-Richtmaschinen und besondere Verhältnisse beim Richten in Zwei-Walzen-Maschinen. Spannungen im Stab, Beanspruchung des Werkstoffs. Ausbildung der plastischen Bereiche, Richtkraft und Antriebsmomente bei freier Biegung und bei Biegung mit Querprägen.     

Richtspaltform und Bewegungsverhältnisse beim Richten von Rundstäben in Zwei-Walzen-Richtmaschinen

Besonderheiten des Zwei-Walzen-Richtens. Geometrie des Richtspalts: Schnitt der Biegeebene der Stabachse mit der hyperbolischen und der zylindrischen Walze, Berührungslinien zwischen Stab und Walzen, Biegelinie der Stabachse und größtmögliche Stabdurchbiegung. Kinematik des Richtvorgangs: Umfangsgeschwindigkeiten der hyperbolischen und der zylindrischen Walze, Vorschub- und Umfangsgeschwindigkeit des Stabes bei freier Biegung des Stabes und bei Biegung mit Querprägen, Schlupf. Anzahl der Biegungen eines Stabelementes und der Überrollungen eines Oberflächenelementes beim Durchlaufen der Maschine.     

Head and eye movements in unrestrained pigeons (Columba livia).

Head and eye movements were simultaneously recorded during locomotory and pecking behavior of 4 pigeons, which were trained to traverse a conditioning chamber, with a pecking key and a food dispenser at each end. Each trial involved key pecking, walking, and feeding. Head movements were registered with a skull-mounted miniature accelerometer, and eye movements were recorded with implanted electrooculogram (EOG) electrodes. An almost perfect temporal coordination between head and eye movements was observed during both walking and feeding bouts. During walking, head movements primarily provide retinal image stability, and eye movements support visual scanning. During feeding, head movements mainly subserve the grasping of food items, and eye movements maintain visual fixation on them. Because the eyes are reflexively closed during the middle phase of pecks, the head and eye movements are then under ballistic control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tracking the mind during reading: The influence of past, present, and future words on fixation durations.

Reading requires the orchestration of visual, attentional, language-related, and oculomotor processing constraints. This study replicates previous effects of frequency, predictability, and length of fixated words on fixation durations in natural reading and demonstrates new effects of these variables related to 144 sentences. Such evidence for distributed processing of words across fixation durations challenges psycholinguistic immediacy-of-processing and eye-mind assumptions. Most of the time the mind processes several words in parallel at different perceptual and cognitive levels. Eye movements can help to unravel these processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Eye Movements and Behavioral Responses to Threatening and Nonthreatening Stimuli During Visual Search in Phobic and Nonphobic Subjects.

Spider-phobic and nonphobic subjects searched for a feared/fear-relevant (spider) or neutral target (mushroom) presented in visual matrices of neutral objects (flowers). In half of the displays, the mushroom target was paired with a spider distractor, or a spider target was paired with a mushroom distractor. Although all subjects responded faster to the neutral target than to the feared/fear-relevant target, phobics were slower to respond than nonphobics when a mushroom target was presented with a spider distractor. Their eyes appeared to be drawn to the feared distractor before fixating neutral targets. A further experiment indicated no group differences when subjects merely judged the homogeneity of matrices. Thus, threat seems to capture the attention of phobics only when it is part of a background that subjects are explicitly instructed to ignore. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

VC Management for Heterogeneous QoS Multicast Transmissions

A crucial component of the interaction between ATM's and the Internet's Quality of Service (QoS) architectures is the efficient mapping of RSVP (Resource reSerVation Protocol) as the Internet's signalling protocol onto the according ATM mechanisms. In particular, this article focuses on one of the most contrary characteristics of RSVP and ATM signalling. This is the support for heterogeneous reservations by RSVP over the ATM subnetwork, taking into account that ATM only allows for a homogeneous QoS within a single Virtual Circuit (VC). We present previous approaches to the solution of this problem and argue for more sophisticated and efficient approaches to manage ATM VCs taking into consideration ATM tariffs and resource consumption.