Theta 13 Determination with Nuclear Reactors

Recently there has been a lot of interest around the world in the use of nuclear reactors to measure theta 13, the last undetermined angle in the 3-neutrino mixing scenario. In this paper the motivations for theta 13 measurement using short baseline nuclear reactor experiments are discussed. The features of such an experiment are described in the context of Double Chooz, which is a new project planned to start data-taking in 2008, and to reach a sensitivity of sinsq(2 theta 13) < 0.03.Comment: Submission for XXXIXth Rencontres de Moriond, Electroweak Interactions and Unified Theories, held in La Thuile, Italy, March 2004 (9 pages 4 figures

Sensitivity of seismically cued antineutrino detectors to nuclear explosions

We evaluate the sensitivity of large, gadolinium-doped water detectors to antineutrinos released by nuclear fission explosions, using updated signal and background models and taking advantage of the capacity for seismic observations to provide an analysis trigger. Under certain realistic conditions, the antineutrino signature of a 250-kiloton pure fission explosion could be identified several hundred kilometers away in a detector about the size of the largest module currently proposed for a basic physics experiment. In principle, such an observation could provide rapid confirmation that the seismic signal coincided with a fission event, possibly useful for international monitoring of nuclear weapon tests. We discuss the limited potential for seismically cued antineutrino observations to constrain fission yield, differentiate pure fission from fusion-enhanced weapon tests, indicate that the seismic evidence of an explosion had been intentionally masked, or verify the absence of explosive testing in a targeted area. We conclude that advances in seismic monitoring and neutrino physics have made the detection of explosion-derived antineutrinos more conceivable than previously asserted, but the size and cost of sufficiently sensitive detectors continue to limit applications

Liquid droplets on a free-standing glassy membrane: deformation through the glass transition

In this study, micro-droplets are placed on thin, glassy, free-standing films where the Laplace pressure of the droplet deforms the free-standing film, creating a bulge. The film's tension is modulated by changing temperature continuously from well below the glass transition into the melt state of the film. The contact angle of the liquid droplet with the planar film as well as the angle of the bulge with the film are measured and found to be consistent with the contact angles predicted by a force balance at the contact line.Comment: 6 pages, 5 figure

Felület-morfológiai eljárás kifejlesztése szilárd peremek adaptív optimalizálására = Development of Surface Morphing Method for the Adaptive Optimisation of Solid Wall

A jelen kutatás célja egy olyan új felület-morfológiai elven működő numerikus áramlástani eljárás kidolgozása, amely képes az áramlást határoló szilárd falak adaptív optimalizálására. A Navier-Stokes és Euler megoldók FORTRAN és C++ környezetben való elkészítését és áramlástani validációját követően az a következtetés vonható le, hogy az összenyomható áramlás modellezése a súrlódás elhanyagolásával is kielégítő eredményt szolgáltat a mérési eredményekkel való összehasonlításakor a vizsgált esetekben. Ezért, az optimalizációs módszer a 2D-s Euler egyenletek strukturált, cellaközpontú véges térfogat elven működő numerikus megoldásán alapul. Az optimalizációs modul első részében állíthatók elő az optimális fali nyomás-eloszlás görbék a végpontokban jelentkező inkonzisztencia (pl. negatív lapátvastagság, nyitott kilépő él) miatt szükséges finomhangolásokkal. A második részben, egy inverz tervező-eszköz segítségével jön létre az a 3-10 iterációt magába foglaló folyamat, amelynek során kialakul az előírt nyomáseloszláshoz tartozó geometria. Az eljárás helyes működésének tesztelése, vagyis a szilárd falak alkalmazástól függő optimális előállítása belső-, külső-, és lapátrácsban kialakult áramlások segítségével történt meg. A módszer a gyakorlati életben jelentősen lerövidítheti az áramlás és teljesítmény szempontjából optimális geometria előállításának irányába tett erőfeszítéseket. Az eljárás pontossága 3D-s kiterjesztéssel és a súrlódás figyelembevételével tovább növelhető. | The goal of the present research is to develop a new CFD (Computational Fluid Dynamics) based surface-morphing method for an adaptive optimization of solid walls. After implementing the Navier-Stokes and Euler solvers in FORTRAN and C++ environment, several analyses have been completed for validation. Beside the viscous flow modeling, the result of the inviscid approach also shows acceptable agreement with the measurement in the investigated cases, hence Euler equations are used as governing equations hereafter. Cell centered finite volume method has been implemented with Roe’s approximated Riemann solver, higher order spatial discretization and MinMod limiter for the numerical solution of the non-linear system of the partial differential equations. The optimal pressure distributions are generated in the first part of the optimization module with fine-tuning process to avoid geometry problems such as negative thickness or opening trailing edge. The second part of the optimization procedure forms the desired geometry over an evolution strategy belongs to the optimal pressure distribution by means of an inversed design solver. Generally, the optimum geometry is appeared within 3-10 iteration cycles. The testing of the correct operation of the entire optimization process has been successfully completed for internal, external and cascade flows. The industrial application of the presented method can significantly reduce time, cost and capacity in the pre- and serial developments

Karsztformák mészkőfeküjének vizsgálata = The investigation of limestone substrate of the karst forms

Vizsgálataink kiterjedtek a teljesen és részben vagy egyáltalán nem fedett karsztokra. A fedett karsztos mélyedések elhelyezkedhetnek a fekü kiemelkedése, oldallejtője és mélyedése felett. A Bakony-hegységben a fedett karsztos mélyedések elsősorban magaslat felett alakultak ki, ahol a fedőüledék vékony. A kitöltött mélyedések felett főleg posztgenetikus fedett karsztos formák képződnek. A Bakonyban a fedőüledékekben képződött nagyobb formák (depressziók) ott alakulnak ki, ahol fedett karsztos formák fordulnak elő, ill. a fekü magaslatokat formál. A mecseki fedett karsztos formák magaslatok felett, valamint idősebb karsztosodás során kialakult részben, vagy teljesen kitöltött dolinák felett képződtek. E formák agyagösszletek elvégződésénél fejlődtek ki. Fedetlen karsztokon idősebb uvalák kitöltődése miatt (Bükk-h.) lokális fedett karsztos térszínek (depressziók) alakultak ki. Területükön fedett karsztosodás megy végbe. A hegység tányéros töbrei olyan áltöbrök, amelyek elfedődött (kibélelt) uvalák. A sortöbrökben (Kis-fennsík) végrehajtott vizsgálataink szerint a völgytalp nagyobb kiterjedésű leoldódása történt. E hely felett elhelyezkedő sortöbrök a fedőüledékek lokális tömörödésével jöttek létre. Az Aggteleki karszton kőzethatár mentén végrehajtott vizsgálatok arra utalnak, hogy itt hosszabb ideje folyik karsztosodás. Ez részben víznyelőképződés, részben fedett karsztosodás. | We examined karsts which are partly or totally covered and uncovered karsts. Covered karst forms can be found above the elevation of the limestone floor, above its side slopes and its depression. Covered karst forms are above elevations in the Bakony Mountains where the covering sedimentary rock is thin. Mainly postgenetycal covered karst forms develop above filled depressions. Greater forms of the covered sedimentary rock develop in the Bakony Mountains, where elevations occur on the limestone floor. Covered karst forms of the Mecsek Mountains occur above elevations of the limestone floor, but mainly they developed above older dolinas. These covered karst forms occur where muds beds wedge out. Due to the infilling of older uvalas of the uncovered karst (Bükk Mountains) locally covered karst surfaces develop. Covered karstification happens in their areas. Plate dolinas of the mountain are pseudodolinas which developed from the filling of the uvalas. According to our research and examinations performed in a few dolinas (Kis Plateau), dissolution occurred in a great expansion on the bottom of the valley. By local gathering of the covering sedimentary rock dolinas are created above this place. According to our investigation on Aggtelek karst which happened along junction, there has been karstification in this place for longer period of time. The karstification is partly the development of sinkholes or covered karstification

Snap-off production of monodisperse droplets

We introduce a novel technique to produce monodisperse droplets through the snap-off mechanism. The methodology is simple, versatile, and requires no specialized or expensive components. The droplets produced have polydispersity <1% and can be as small as 2.5 $\mu$m radius. A convenient feature is that the droplet size is constant over a 100-fold change in flow rate, while at higher flows the droplet size can be continuously adjusted.Comment: to be published in Eur. Phys. J. E as a "Tips and Tricks" articl

Report of review of St Stephen’s Children’s Centre, Newham: services for children aged up to 3 years

Formation of surface depressions is a significant geological hazard. Prediction of future sinkholes in buried karstic areas needs knowledge about the subsurface. In order to determine the varying topography of the karstifiable bedrock we carried out multielectrode measurements. Due to the hard field conditions, the bedrock depth could not be detected. The resistivity anomalies in some places had a seasonal variation (low-resistivity in springtime, high-resistivity in the end of summer); therefore we interpreted the springtime resistivity lows as indicators of locations with high water content, that is as high porosity, saturated with water. At the same time, when pushing the current- and potential electrodes into the ground, we discovered a regularity in the areal distribution of the soil's rock debris content. Therefore we carried out a systematic electrode-pricking experiment, and categorized the soil's "toughness" corresponding to soft penetration, scratching or blockage within the upper 30 cm. We have found a close relationship between the locations of resistivity- and the soil's toughness extremes. From some epikarstic features we think that high "pricking probe" values indicate smaller depths of the bedrock. The corresponding (springtime) resistivity minima may indirectly indicate more or less collapsed horsts of the carbonate rock