Counter Rotating Open Rotor Animation using Particle Image Velocimetry

This article describes the two accompanying fluid dynamics videos for the "Counter rotating open rotor flow field investigation using stereoscopic Particle Image Velocimetry" presented at the 64th Annual Meeting of the APS Division of Fluid Dynamics in Baltimore, Maryland, November 20-22, 2011.Comment: Videos are include

Trapped acoustic waves and raindrops: high-order accurate integral equation method for localized excitation of a periodic staircase

We present a high-order boundary integral equation (BIE) method for the frequency-domain acoustic scattering of a point source by a singly-periodic, infinite, corrugated boundary. We apply it to the accurate numerical study of acoustic radiation in the neighborhood of a sound-hard two-dimensional staircase modeled after the El Castillo pyramid. Such staircases support trapped waves which travel along the surface and decay exponentially away from it. We use the array scanning method (Floquet--Bloch transform) to recover the scattered field as an integral over the family of quasiperiodic solutions parameterized by their on-surface wavenumber. Each such BIE solution requires the quasiperiodic Green's function, which we evaluate using an efficient integral representation of lattice sum coefficients. We avoid the singularities and branch cuts present in the array scanning integral by complex contour deformation. For each frequency, this enables a solution accurate to around 10 digits in a couple of seconds. We propose a residue method to extract the limiting powers carried by trapped modes far from the source. Finally, by computing the trapped mode dispersion relation, we use a simple ray model to explain an observed acoustic "raindrop" effect (chirp-like time-domain response).Comment: 25 pages, 11 figures. Submitted to JC

A web service based on RESTful API and JSON Schema/JSON Meta Schema to construct knowledge graphs

Data visualisation assists domain experts in understanding their data and helps them make critical decisions. Enhancing their cognitive insight essentially relies on the capability of combining domain-specific semantic information with concepts extracted out of the data and visualizing the resulting networks. Data scientists have the challenge of providing tools able to handle the overall network lifecycle. In this paper, we present how the combination of two powerful technologies namely the REST architecture style and JSON Schema/JSON Meta Schema enable data scientists to use a RESTful web service that permits the construction of knowledge graphs, one of the preferred representations of large and semantically rich networks.Comment: 5 pages; 6 figure

Progress in Developing Hybrid RPCs: GEM-like Detectors with Resistive Electrodes

We have recently developed an innovative detector of photons and charged particles: a GEM-like gaseous amplification structure with resistive electrodes instead of commonly used metallic ones. This novel detector combines the best property of GEMs- the capability to operate in a cascaded mode and in poorly quenched gases - and of RPC: the protection against sparks. In this paper will shortly review our latest achievements in this direction, however the main focus will be given on a new advanced design that allows to build large area detectors manufactured by a screen printing technology. The proposed detector, depending on the applications, can operate either in a GEM mode (electron multiplications through holes only) or as a hybrid RPC with simultaneous amplifications in the drift region and in the holes. The possible applications of this new detector will be discussed

Reconstruction of Space Steel Constructions

p. 1328-1337Reconstruction of some special types of constructions - silos, timber roof structure and a winter stadium are described. The silos are cylindrical with a diameter of 36.0m with a total height of 50.5m. The silo shell is made from steel plates of variable thickness. Capacity of the silo is 60 000t. Gradually, during more than 30 years of operation, local deformations and distinctive 6000mm high cracks in the bottom part of the shells of the silos developed. On the basis of diagnostic inspections and control static calculation a strengthening was proposed. To increase working life of the clinker silos, the shell strengthening over the whole height of the cylindrical body by means of horizontal rings and vertical stiffeners was designed. The total S355 steel consumption for strengthening of one silo shell was 300t. The original roof structure of a winter stadium in Zvolen was made of timber glued beams with span of 55.5m. Some problems occurred during years of serving to its purpose. Diagnostics showed that construction is unsatisfactory for the ultimate and serviceability limit states. Deflection of the roof construction in the year 2005 was more than 500mm. Authors proposed strengthening of the original beams (overall 34pcs) by prestressing. The original reinforced concrete skeleton of Winter Stadium in Bratislava with plan dimensions of 70.0 x 100.0 m was built in 1943-1952. During extensive modernisation of Stadium, its steel roof structure is also prepared for basic reconstruction.Brodniansky, J.; Agocs, Z.; Aroch, R.; Slivansky, M. (2010). Reconstruction of Space Steel Constructions. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/707

Advances in the Development of Micropattern Gaseous Detectors with Resistive Electrodes

We describe the most recent efforts made by various groups in implementing resistive electrodes in micropattern gaseous detectors with the aim to combine in the same design the best features of RPCs (for the example, their robustness and spark protection property) with the high granularity and thus the good position resolution offered by microelectronic technology. In the stream of this activity, we have recently developed two novel detectors with resistive electrodes: one was based on resistive micromeshes and the second one is a MSGC with resistive electrodes. We have demonstrated that the resistive meshes are a convenient construction element for various designs of spark protective detectors: RPCs type, GEM type and MICROMEGAS type. These new detectors enable to considerably enhance the RPC and micropattern detectors applications since they feature not only a high position resolution but also a relatively good energy resolution (25-30 persent FWHM at 6 keV) and, if necessary, they can operate in cascaded mode allowing the achievement of a high overall gas gain. The main conclusion from these studies is that the implementation of resistive electrodes in micropattern detectors makes them fully spark protected; on this basis we consider this direction very promising