Requirements in feature algebra

Feature Algebra is intended to capture the commonalities of feature oriented software development (FOSD), such as introductions, refinements and quantification. It allows denoting systems composed of features by algebraic terms and transforming the systems by manipulating the terms using the laws of the algebra. The algebraic view abstracts from differences of minor importance and leads to more compact and effective reasoning. While the existing Feature Algebra covers most of the main aspects of FOSD, so far requirements have not been integrated into it. They naturally arise in connection with different aspects of feature orientation, such as feature elicitation, feature dependence, mutual feature exclusion and feature interaction. This paper presents a possibility for integrating requirements into Feature Algebra

Projection image-to-image translation in hybrid X-ray/MR imaging

The potential benefit of hybrid X-ray and MR imaging in the interventional environment is large due to the combination of fast imaging with high contrast variety. However, a vast amount of existing image enhancement methods requires the image information of both modalities to be present in the same domain. To unlock this potential, we present a solution to image-to-image translation from MR projections to corresponding X-ray projection images. The approach is based on a state-of-the-art image generator network that is modified to fit the specific application. Furthermore, we propose the inclusion of a gradient map in the loss function to allow the network to emphasize high-frequency details in image generation. Our approach is capable of creating X-ray projection images with natural appearance. Additionally, our extensions show clear improvement compared to the baseline method.Comment: In proceedings of SPIE Medical Imaging 201

Sweet home Alaska

Im Zentrum dieser Diplomarbeit steht Alaska, das als Sinnbild für unberührte Natur, endlose Wälder und Seen und beeindruckende Bergketten zu sehen ist. Schauplatz der beiden Fernsehsendungen „Men in Trees“ und „Northern Exposure“ (deutscher Titel: Ausgerechnet Alaska) ist eben dieses Alaska, das von den beiden Protagonisten der Serie, Marin und Joel, zunächst nicht als besonders einladend wahrgenommen wird. Beide stammen ursprünglich aus New York, und schon hier zeichnet sich eine der Dichotomien ab, die im Laufe dieser Arbeit besonders wichtig sind. Stadt – Land, Natur – Mensch, Raum – Ort, diese gegensätzlichen Paare sind der Ausgangspunkt für die Untersuchungen. Alaska, als Ausgangspunkt für diese Arbeit, bietet ein Beispiel für die ikonenhafte Repräsentation von Orten, und die Art und Weise, wie Alaska in Verbindung damit Natur dargestellt wird, sind die wesentlichen Elemente

EVALUATION OF FATIGUE DAMAGE BY X-RAY DIFFRACTION TECHNIQUE OF STEAM TURBINE ROTOR STEELS AT ELEVATED TEMPERATURES

ABSTRACT In many industrial applications materials are subjected to degradation of mechanical properties as a result of real service conditions. The assessment of the remaining lifetime of components and structures is commonly based on correlated procedures including numerous destructive, nondestructive and mathematical techniques that should guarantee reasonable precise assessment of the current damage extent of materials in question and the remnant lifetime assessment. The assessment of the remaining lifetime by X-ray diffraction technique is based on the fact that mechanical properties of the most materials depend strongly on crystallite size and orientation of ingredients, which are the crucial parameters for the determination of the ageing state and the prediction of residual lifetime of the components

SEM imaging of in-situ tensile testing of steam turbine rotor steel CSN 416236

Byla provedena in-situ zkouška tahem oceli 27CrNiMoV v komoře elektronového rastrovacího mikroskopu za použití deformačního stolku. Ocel 27CrNiMoV (ČSN 416236) se používá pro rotory parních turbín. Během experimentu byla zkoumána deformace a tvorba a šíření trhlin. Z oceli byly připraveny malé ploché vzorky (45 x 10 x 1,5 mm, s počáteční měřenou délkou 25 mm), ve tvaru kosti. Materiál v počátečním stavu obsahoval vysoký počet defektů ve formě mikrotrhlin. Při tahových zkouškách bylo provedeno srovnání chování vzorků bez viditelné vady a vzorků s trhlinou v těle vzorku. Přítomnost vady v počátečním stavu zjevně ukázala přímý vliv na vlastnosti materiálu, jako je nižší pevnost v tahu. Vzorek, jeho zúžení v testované části (tvorba krčku) a šířící se trhlina jsou zobrazeny v různých fázích tahového zatížení. Při testování in-situ je možno pozorovat rozdíly v deformaci vzorku. Vzorek bez vad je ovlivněn v celém těle a lze pozorovat správné zúžení, zatímco přítomnost trhliny ve vzorcích vady soustředí napětí na menší plochu a také změnilo tvar křivky napětí-prodloužení.Tento příspěvek vznikl v rámci projektu LO1502 Rozvoj Regionálního technologického institutu podpořeného programem Ministerstva školství, mládeže a tělovýchovy na podporu výzkumu, experimentálního vývoje a inovací Národní program udržitelnosti I („NPU I“).In-situ tensile testing of a 27CrNiMoV alloy which is used for steam turbine rotors was carried out using scanning electron microscope (SEM). Deformation and crack formation and propagation was examined using this test. Small (45 x 10 x 1,5 mm, with gauge length 25 mm), flat samples based on dog-bone shape were prepared from the steel. The material in its initial state contained big number of defects in form of microcracks. A comparison of behavior at tensile tests of samples without visible defect and with crack in the gauge section was performed. Apparently, the presence of defect in the initial state showed direct influence on properties like lower tensile strength. The sample, its necking and propagated crack is displayed at different stages of the tensile load. In-situ testing reveal differences in the sample deformation. The defect-free sample is affected in its whole body and proper necking can be observed, whereas the presence of the crack in the defect samples concentrates stress to a smaller area and also changed the shape of the stress-strain curve

Dynamic compression testing by means of Charpy pendulum

Mathematical modelling and virtual testing of components and structures represent a useful and economic tool for design and safety assessment. The basic mechanical properties which can be found in material standards are not relevant in cases where the real service conditions differ from those applied during standardised testing. Thus e.g. mechanical behaviour at higher strain rates can be interesting for the car components when the simulation of crash situations is used during structure development. The dynamic compression tests are usually performed by means of drop towers, by means of high speed hydraulic testing machines or Hopkinson bar method. At the Mechanical Testing Laboratory of the SKODA Research Inst. in Pilsen, Czech Republic, an instrumentation of Charpy pendulum testing machine was realised in order that it was possible to perform dynamic compression tests [Mentl V., Dzugan J.: Impact compression and tensile testing by means of Charpy pendulum, Int. conf. SUSI 2008 (Structures under Shock and Impact), Algarve, Portugal, 5/2008.], and the compatibility of obtained results in comparison with traditional impact compression tests was verified within the round–robin carried out by TC5 ESIS Sub-Committee on “Mechanical Testing at Intermediate Strain Rates” [Dzugan J., Mentl V.: Compression Round Robin Test Results, ESIS TC5 Meeting, CORUS UK, 2007]. A new striking tup and load measurement system were designed and calibrated. At the same time, a new software was developed which makes it possible to evaluate the test force-deformation record. The goal of this study was 1. to check the possibility of compression testing of high strength materials by means of Charpy pendulum, and 2. to study the strain rate influence on basic mechanical properties

Fatigue testing of miniature test specimens and correlation of the results with the standard test specimens

This paper deals with the correlation of the fatigue tests results obtained on standard and miniature test samples. The aim was to compare the fatigue properties (Wöhler curves) of the samples of 15CH2NMFA steel of different cut off CT/50 test specimens after fracture toughness tests. The advantage of the use of these miniature samples is the minimum volume of removed material necessary for the production of test samples. This makes it possible to check the components in service, e.g. pressure vessels, steam turbine casings and rotors, steam pipelines, and other components of power plants after some time of operation in order that the residual lifetime could be determined. The article discusses the design of tests samples and clamping fixtures, test conditions and resulting correlation of test results