Two-phase flow measurements with spacer grid in a rod bundle geometry

Heat transfer effectiveness in nuclear rod bundles is of great importance to nuclear reactor safety and economics. An important design parameter is the Critical Heat Flux (CHF), which limits the transferred heat from the fuel to the coolant. The CHF is determined by flow behaviour, especially the turbulence created inside the fuel rod bundle. Adiabatic experiments can be used to characterize the flow behaviour separately from the heat transfer phenomena in diabatic flow. To enhance the turbulence, mixing vanes are attached to spacer grids, which hold the rods in place. The vanes either make the flow swirl around a single sub-channel or induce cross-mixing between adjacent sub-channels. In adiabatic two-phase conditions an important phenomenon that can be investigated is the effect of the spacer on canceling the lift force, which collects the small bubbles to the rod surfaces leading to decreased CHF in diabatic conditions and thus limits the reactor power. Computational Fluid Dynamics (CFD) can be used to simulate the flow numerically and to test how different spacer configurations affect the flow. Experimental data is needed to validate and verify the used CFD models. Especially the modeling of turbulence is challenging even for single-phase flow inside the complex sub-channel geometry. In two-phase flow other factors such as bubble dynamics further complicate the modeling. To investigate the spacer grid effect on two-phase flow, and to provide further experimental data for CFD validation, a series of experiments was run on an adiabatic sub-channel flow loop using a duct-type spacer grid with different configurations. Utilizing the wire-mesh sensor technology, the facility gives high resolution experimental data in both time and space. The experimental results indicate that the duct-type spacer grid is less effective in canceling the lift force effect than the egg-crate type spacer tested earlier.

Defining the keyhole modes – the effects on the weld geometry and the molten pool behaviour in high power laser welding of stainless steels

Keyhole welding, meaning that the laser beam forms a vapour cavity inside the steel, is one of the two types of laser welding processes and currently it is used in few industrial applications. Modern high power solid state lasers are becoming more used generally, but not all process fundamentals and phenomena of the process are well known and understanding of these helps to improve quality of final products. This study concentrates on the process fundamentals and the behaviour of the keyhole welding process by the means of real time high speed x-ray videography. One of the problem areas in laser welding has been mixing of the filler wire into the weld; the phenomena are explained and also one possible solution for this problem is presented in this study. The argument of this thesis is that the keyhole laser welding process has three keyhole modes that behave differently. These modes are trap, cylinder and kaleidoscope. Two of these have sub-modes, in which the keyhole behaves similarly but the molten pool changes behaviour and geometry of the resulting weld is different. X-ray videography was used to visualize the actual keyhole side view profile during the welding process. Several methods were applied to analyse and compile high speed x-ray video data to achieve a clearer image of the keyhole side view. Averaging was used to measure the keyhole side view outline, which was used to reconstruct a 3D-model of the actual keyhole. This 3D-model was taken as basis for calculation of the vapour volume inside of the keyhole for each laser parameter combination and joint geometry. Four different joint geometries were tested, partial penetration bead on plate and I-butt joint and full penetration bead on plate and I-butt joint. The comparison was performed with selected pairs and also compared all combinations together.

pp-Blast: a "pseudo-parallel" Blast

We have developed a software called pp-Blast that uses the publicly available Blast package and PVM (parallel virtual machine) to partition a multi-sequence query across a set of nodes with replicated or shared databases. Benchmark tests show that pp-Blast running in a cluster of 14 PCs outperformed conventional Blast running in large servers. In addition, using pp-Blast and the cluster we were able to map all human cDNAs onto the draft of the human genome in less than 6 days. We propose here that the cost/benefit ratio of pp-Blast makes it appropriate for large-scale sequence analysis. The source code and configuration files for pp-Blast are available at http://www.ludwig.org.br/biocomp/tools/pp-blast.

Coolability of porous core debris beds : Effects of bed geometry and multi-dimensional flooding

This thesis addresses the coolability of porous debris beds in the context of severe accident management of nuclear power reactors. In a hypothetical severe accident at a Nordic-type boiling water reactor, the lower drywell of the containment is flooded, for the purpose of cooling the core melt discharged from the reactor pressure vessel in a water pool. The melt is fragmented and solidified in the pool, ultimately forming a porous debris bed that generates decay heat. The properties of the bed determine the limiting value for the heat flux that can be removed from the debris to the surrounding water without the risk of re-melting. The coolability of porous debris beds has been investigated experimentally by measuring the dryout power in electrically heated test beds that have different geometries. The geometries represent the debris bed shapes that may form in an accident scenario. The focus is especially on heap-like, realistic geometries which facilitate the multi-dimensional infiltration (flooding) of coolant into the bed. Spherical and irregular particles have been used to simulate the debris. The experiments have been modeled using 2D and 3D simulation codes applicable to fluid flow and heat transfer in porous media. Based on the experimental and simulation results, an interpretation of the dryout behavior in complex debris bed geometries is presented, and the validity of the codes and models for dryout predictions is evaluated. According to the experimental and simulation results, the coolability of the debris bed depends on both the flooding mode and the height of the bed. In the experiments, it was found that multi-dimensional flooding increases the dryout heat flux and coolability in a heap-shaped debris bed by 47–58% compared to the dryout heat flux of a classical, top-flooded bed of the same height. However, heap-like beds are higher than flat, top-flooded beds, which results in the formation of larger steam flux at the top of the bed. This counteracts the effect of the multi-dimensional flooding. Based on the measured dryout heat fluxes, the maximum height of a heap-like bed can only be about 1.5 times the height of a top-flooded, cylindrical bed in order to preserve the direct benefit from the multi-dimensional flooding. In addition, studies were conducted to evaluate the hydrodynamically representative effective particle diameter, which is applied in simulation models to describe debris beds that consist of irregular particles with considerable size variation. The results suggest that the effective diameter is small, closest to the mean diameter based on the number or length of particles.

A beleza no ritmo pseudo-dionisiano da processão/conversão

No contexto da Metafísica Medieval, a «beleza» foi pensada como um conceito ambíguo: ora atribuído a Deus, ora atribuído ao Mundo. O propósito deste artigo é clarificar o sentido desta ambiguidade no âmbito da filosofia do Pseudo-Dionísio Areopagita. Se, portanto, o conceito de «beleza» é, em primeiro lugar, despojado do seu carácter sensível e mundano, para ser apropriado à natureza divina, ele é, num segundo momento, aposto à própria criação, de forma a designar a manifestação visível da beleza transcendente e o chamamento vital para a perscrutação teológica.

Nicolaus Trevet Anglicus, Expositio in Boethium de consolatione philosophiae (1-166v). - Pseudo-Boethius, De disciplina scolarium (167-184v).

Ce ms. a appartenu à l'église paroissiale de Chaumont-en-Bassigny (Haute-Marne), comme en témoigne la mention du XVe s. "Ce livre cy appartient a l'eglise de Chaumont" (f. 184). En-dessous de cette mention figure la signature "H. Vigniery" (XVIe s.). En 1655, Claude Joly, chantre de Notre-Dame de Paris, l'a acheté à cette église (cf. l'inscription au contreplat sup., datée d'octobre 1658). Il a ensuite appartenu à la bibliothèque du chapitre de Notre-Dame de Paris, dont il porte l'ex-libris "A la bibliotheque de l'Eglise de Paris", précédé de la cote L5 (XVIIe s., contreplat sup.). Notre-Dame.

JACQUES DE VITRY, PSEUDO-TURPIN, Chroniques françaises, etc.

Contient : Histoire abrégée de Jérusalem, par JACQUES DE VITRY, traduction française du livre Ier. Début : « Puis que la misericorde Nostre Segneur ... (Table de cent chapitres.) I. La sainte tiere de promission... » — Fin. (xc) : « ... Nos ne navions point par mer por marceander, car en la mer on soefre moult de... » ; Chronique du PSEUDO-TURPIN, traduite en français par PIERRE. Incomplète du début : «... quant uns rois de France i venroit... » — Fin : « ... si ont encore non cil de Navare et aront tous jors, car cil qui les encacierent les nommerent ensi. Ci fine l'estoire de Carlemainne et de ses gens » ; Chronique abrégée des rois de France, s'arrêtant à l'année 1204. Début : « Si com nous trovons en escrit es anciens livres, Troies fu ancianement... — Fin : « ... par le commant au roi Jehan meisme, qui secorre ne les pooit. A tant s'en taist la matere. Amen. » — Suivent (f. 68) quelques notes sur les événements des années 1244-1249, qui occupent une colonne et se terminent par les mots : « ... et le diemence par matin, à l'eure de miedi, li rois entra en Damiete a toutes ses gens et n'i troverent que I. peu de gens, car li Sarrasin estoient tout fuit. » (Cf. Notices et extraits des mss., XXXII, II, 57) ; Chronique d'un anonyme de Béthune, s'arrêtant à l'année 1220, publiée par Fr. Michel, en 1840, sous le titre de Histoire des ducs de Normandie et des rois d'Angleterre (Société de l'histoire de France) ; L'Ordre de chevalerie, en prose. Début : « Ci en droit dist li contes que au tans le roi Salehadin ... » — Fin : « ... et ausi fu il au prince de Galilée. Ci faut li contes de mon seigneur Huon de Tabarie, le prince de Galilée et de Salehadin »

Histoire de France ou Chronique Saintongeaise, suivie d'une traduction du Pseudo-Turpin, le tout en dialecte Saintongeais.

Contient : 1° Histoire de France ; 2° Traduction de la chronique du Pseudo-Turpin

La Vie des Pères. — Les miracles de saint Jaques. — Pseudo-Turpin. — Amis et Amile.

Contient : « De la vie des Peres et de aucuns autres examples, » en vers ; « Livre Calixte apostoile des miracles saint Jasque de de Galice. » Début : « Calixtes, avasques, sers des sers de Deu, a seint Conant de Cluigney... » ; « Proemes saint Calixte en la passion saint Eutrope. » Début : « Sainz Eutropes, avasques et martyrs, giet en la cité... » ; La chronique de Turpin ou Pseudo-Turpin. Début : « Après de ce que sainz Jasques, qui premiers en Galice fust raporté par la mer des Jherusalem... » Cf. La Chronique de Turpin, publiée d'après les mss. B. n. 1850 et 2137, par Fredrik Wulff (Lund, 1881, in-4°) ; « Des sainz que li pelerin requierent en la voie saint Jasque. » Début : « Cil qui vont a saint Jasque par la voie Egidiaine requierent le cors saint Trophin... » ; « Li amitiez de Ami et Amile. » Début : « A temps de Pupin, roi de Frans, fu uns anfez néz... » Cf. Moland et d'Héricault, Nouvelles françoises en prose du xiiiesiècle (Paris, 1856, in-16), p. xxxi. — Catalogue... de La Vallière, t. II, p. 175, n° 2713 A

代微積拾級Dai wei ji shi ji.Loomis' Analytical Geometry and Differential and Integral Calculus.

Traduction de Wylie, rédigée par Li Shan lan ; préfaces Chinoises des deux traducteurs (1859) ; préface anglaise, écrite à Shang hai par A. Wylie (juillet 1859). Liste de termes techniques en anglais et en Chinois. Gravé à la maison Mo hai (1859).18 livres.