Arc Simulation at Shunt-Reactor Switching in H.V. Circuit Breakers

High energy re-ignitions occur in h.v. circuit breakers, when interrupting shunt-reactor currents. The es-calating high frequency over-voltages, which are proportional to the arcing time, are stressful both to the reactor and the circuit breakers. We simulated the electric, thermal and flow field inside the thermal chamber and determined the reduced electric field distribution. Analysing the simulation results the main factors to improve the shunt-reactor breaking capacity are demonstrated

Structure and thermal behaviour of dichlorobis(thiourea)cadmium(ii), a single-source precursor for CdS thin films

The title compound (1) crystallites in the space group Pmn2(1) with a = 13.110 (3), b = 5.813(1) and c = 6.482(1) Angstrom. Its crystal structure was redetermined from three-dimensional single-crystal data to a final R-value of 0.0221. The Cd2+ ion is tetrahedrally coordinated to two sulfur atoms from the tiourea ligand (Cd-S = 2.509 Angstrom) and to two chloride ions at distances 2.545 and 2.518 Angstrom. When heated in air or in an inert atmosphere 1 undergoes a complex degradation process which was studied in situ by simultaneous TG/DTA as well as by EGA-FTIR. The gaseous species evolved include NH3, HCl, H2NCN, HNCS and CS2, which upon oxidation yield also HCN, SO2, COS and CO2. In the solid residue, NH4CdCl3 and CdS were detected by X-ray diffraction, Elemental and XPS analyses also indicated the presence of Cl and N as well as some carbon residue. The results of the thermoanalytical study are not directly applicable to the spray pyrolysis process because of the different experimental conditions, but they nevertheless indicate that it is extremely difficult to prepare impurity-free CdS. The formation of HCN, not detected earlier, should also be taken into account when designing the process parameters and safety measures

A logic road from special relativity to general relativity

We present a streamlined axiom system of special relativity in first-order logic. From this axiom system we "derive" an axiom system of general relativity in two natural steps. We will also see how the axioms of special relativity transform into those of general relativity. This way we hope to make general relativity more accessible for the non-specialist

Twin Paradox and the logical foundation of relativity theory

We study the foundation of space-time theory in the framework of first-order logic (FOL). Since the foundation of mathematics has been successfully carried through (via set theory) in FOL, it is not entirely impossible to do the same for space-time theory (or relativity). First we recall a simple and streamlined FOL-axiomatization SpecRel of special relativity from the literature. SpecRel is complete with respect to questions about inertial motion. Then we ask ourselves whether we can prove usual relativistic properties of accelerated motion (e.g., clocks in acceleration) in SpecRel. As it turns out, this is practically equivalent to asking whether SpecRel is strong enough to "handle" (or treat) accelerated observers. We show that there is a mathematical principle called induction (IND) coming from real analysis which needs to be added to SpecRel in order to handle situations involving relativistic acceleration. We present an extended version AccRel of SpecRel which is strong enough to handle accelerated motion, in particular, accelerated observers. Among others, we show that the Twin Paradox becomes provable in AccRel, but it is not provable without IND.Comment: 24 pages, 6 figure

Kapcsolt termoanalitikai módszerek vékony filmek technológiájának fejlesztésében

A termikus analízis, amelynek Magyarországon is nagy hagyományai vannak,1,2 leggyakrabban porított, ill. aprított formájú analitikai mintákat vizsgál. Azonban a termoanalitikai technikák és mérőberendezések, jelenlegi magas összetettségi szintjüknek köszönhetően már ma is képesek vizsgálni olyan hőmérséklet indukálta változásokat, amelyek vékony fi lmekben jelennek meg, ahol a rendelkezésre álló mintamennyiség csekély, rendszerint 1 mg/cm2 alatt van. Ez kiszélesíti a termikus analízis alkalmazhatósági körét a vékonyfi lm-technológiához, mely kulcsszerepet játszik új anyagok, folyamatok és eszközök kifejlesztésében, különösen a mikroelektronikai és optoelektronikai ipar számára. 3,4 Egyik nem túl régi példája a mind vékony rétegek mind porok formájában igen jelentős alkalmazási potenciállal bíró új anyagoknak a magas hőmérsékletű szupravezetők. A termikus analízist ezen új oxidkerámia anyagok tanulmányozására már rögtön a felfedezésük után alkalmazni kezdték, és különösen a szupravezetők szintézisében és a kívánatos oxigéntartalmuk, ill. oxigénsztöchiometriájuk jellemzésére a termoanalitikai módszerek elengedhetetleneknek bizonyultak.5-7 Általában elmondható, hogy a termikus analízis most válik azon technikáknak az egyik gyakran használt csoportjává, amelyek képesek problémamegoldásra a vékonyfi lmek formájában leválasztásra és jellemzésre kerülő anyagok körében. A termikus analízis megnövekedett használatának egyik oka, többek között, a vékony fi lmek kémiai leválasztási módszereinek a mind gyakoribb alkalmazása, amelyek során a prekurzoranyagok és leválasztás kémiai folyamatai kényelmesen tanulmányozhatók a termikus analízis eszközeivel

Atomic Force Microscopy of height fluctuations of fibroblast cells

We investigated the nanometer scale height fluctuations of 3T3 fibroblast cells with the atomic force microscope (AFM) under physiological conditions. Correlation between these fluctuations and lateral cellular motility can be observed. Fluctuations measured on leading edges appear to be predominantly related to actin polymerization-depolymerization processes. We found fast (5 Hz) pulsatory behavior with 1--2 nm amplitude on a cell with low motility showing emphasized structure of stress fibres. Myosin driven contractions of stress fibres are thought to induce this pulsation.Comment: 6 pages, 5 figures, 1 tabl

Changing a semantics: opportunism or courage?

The generalized models for higher-order logics introduced by Leon Henkin, and their multiple offspring over the years, have become a standard tool in many areas of logic. Even so, discussion has persisted about their technical status, and perhaps even their conceptual legitimacy. This paper gives a systematic view of generalized model techniques, discusses what they mean in mathematical and philosophical terms, and presents a few technical themes and results about their role in algebraic representation, calibrating provability, lowering complexity, understanding fixed-point logics, and achieving set-theoretic absoluteness. We also show how thinking about Henkin's approach to semantics of logical systems in this generality can yield new results, dispelling the impression of adhocness. This paper is dedicated to Leon Henkin, a deep logician who has changed the way we all work, while also being an always open, modest, and encouraging colleague and friend.Comment: 27 pages. To appear in: The life and work of Leon Henkin: Essays on his contributions (Studies in Universal Logic) eds: Manzano, M., Sain, I. and Alonso, E., 201

From BIM towards digital twin: Strategy and future development for smart asset management

With the rising adoption of Building Information Model (BIM) for as-set management within architecture, engineering, construction and owner-operated (AECO) sector, BIM-enabled asset management has been increasingly attracting more attentions in both research and practice. This study provides a comprehensive review and analysis of the state-of-the-art latest research and industry standards development that impact upon BIM and asset management within the operations and maintenance (O&M) phase. However, BIM is not always enough in whole-life cycle asset management, especially in the O&M phase. Therefore, a framework for future development of smart asset management are proposed, integrating the concept of Digital Twin (DT). DT integrates artificial intelligence, machine learning and data analytics to create dynamic digital models that are able to learn and update the status of the physical counterpart from multiple sources. The findings will contribute to inspiring novel research ideas and promote wide-spread adoption of smart DT-enabled asset management within the O&M phaseCentre for Digital Built Britain, Innovate U