Method of making an apertured casting

An apertured casting is made by first forming a duplicate in the shape of the finished casting, positioning refractory metal bodies such as wires in the duplicate at points corresponding to apertures or passageways in finished products, forming a ceramic coating on the duplicate, removing the duplicate material, firing the ceramic in a vacuum or inert atmosphere, vacuum casting the metal in the ceramic form, removing the ceramic form, heating the cast object in an atmospheric furnace to oxidize the refractory metal bodies and then leaching the oxidized refractory bodies from the casting with a molten caustic agent or acid solution

Evaluation of a laboratory test model annular momentum control device

A 4068 Nm Sec laboratory test model annular momentum control device (AMCD) was described and static and dynamic test results were presented. An AMCD is a spinning annular rim suspended by noncontacting magnetic bearings and powered by a noncontacting linear electromagnetic motor. Test results include spin motor torque characteristics and spin motor and magnetic bearing drag losses. Limitations of some of the design approaches taken was also discussed

Humanitarian Action and Military Intervention: Temptations and Possibilities.

Although the war in Liberia in July 2003 claimed hundreds of lives, the international community was reluctant to intervene. In this article, the author debates the question: does international military intervention equal protection of populations? The role of humanitarian organisations in military intervention is considered. Aid organisations cannot call for deployment of a protection force without renouncing their autonomy or appealing to references outside their own practices. Such organisations provide victims with vital assistance and contribute to ensuring that their fate becomes a stake in political debate by exposing the violence that engulfs them, without substituting their own voices for those of the victims. The political content of humanitarian action is also outlined and military intervention in the context of genocide is discussed. The author concludes that the latter is one of the rare situations in which humanitarian actors can consider calling for an armed intervention without renouncing their own logic

Sea surface temperature associations with the late Indian summer monsoon

International audienceThis paper uses recent gridded and historical data in order to assess the relationships betweeninterannual variability of the Indian Summer Monsoon (ISM) and Sea Surface Temperature (SST)anomaly patterns over the Indian and Pacific oceans.Interannual variability of ISM rainfall and dynamical indices for the traditional summer monsoonseason (June-September) are strongly influenced by rainfall and circulation anomalies observedduring August and September, or the Late Indian Summer Monsoon (LISM). Anomalous monsoonsare linked to well-defined LISM rainfall and large-scale circulation anomalies. The east-westWalker and local Hadley circulations fluctuate during the LISM of anomalous ISM years. LISMcirculation is weakened and shifted eastward during weak ISM years. Therefore, we focus on thepredictability of the LISM in this study.Strong (weak) (L)ISMs are preceded by significant positive (negative) SST anomalies in thesoutheastern subtropical Indian Ocean, off Australia, during boreal winter. These SST anomaliesare mainly linked to south Indian Ocean dipole events, recently studied by Behera and Yamagata(2001), and to the El Niño-Southern Oscillation (ENSO) phenomenon. These SST anomalies arehighly persistent and affect the northwestward translation of the Mascarene high from austral toboreal summer. The southeastward (northwestward) shift of this subtropical high associated withcold (warm) SST anomalies off Australia causes a weakening (strengthening) of the wholemonsoon circulation through a modulation of the local Hadley cell during the LISM. Furthermore, itis suggested that the Mascarene high interacts with the underlying SST anomalies through apositive dynamical feedback mechanism, maintaining its anomalous position during the LISM.Our results also explain why a strong ISM is preceded by a transition in boreal spring from an ElNiño to a La Niña state in the Pacific and vice versa. An El Niño event and the associated warmSST anomalies over the southeastern Indian Ocean during boreal winter may play a key role in thedevelopment of a strong ISM by strengthening the local Hadley circulation during the LISM. On theother hand, a developing La Niña event in boreal spring and summer may also enhance the eastwestWalker circulation and the monsoon as demonstrated in many previous studies

Indian Ocean Sea Surface Temperature and El Niño-Southern Oscillation: A New Perspective

International audienceHere we show that the 1976-1977 climate regime shift was accompanied by aremarkable change in the lead-lag relationships between Indian Ocean Sea SurfaceTemperature (SST) and El Niño evolution. After the 1976-1977 regime shift, acorrelation analysis suggests that southern Indian Ocean SSTs observed during lateboreal winter are a key precursor in predicting El Niño evolution as the traditionaloceanic heat content anomalies in the equatorial Pacific or zonal wind anomalies overthe equatorial western Pacific. The possible physical mechanisms underlying this highlysignificant statistical relationship are discussed. After the 1976-1977 regime shift,southern Indian Ocean SST anomalies produced by Mascarene High pulses duringboreal winter trigger coupled air-sea processes in the tropical eastern Indian Oceanduring the following seasons. This produces a persistent remote forcing on the Pacificclimate system, promoting wind anomalies over the western equatorial Pacific andmodulating the regional Hadley cell in the southwest Pacific. These modulations, inturn, excite Rossby waves, which produce quasi-stationary circulation anomalies in theextratropical South Pacific, responsible for the development of the southern branch ofthe “horseshoe” El Niño pattern.The change of the background SST state that occured in the late 1970s over the IndianOcean may also explain why ENSO evolution is different before and after the 1976-1977 regime shift. These results shed some light on the possible influence of globalwarming or decadal fluctuations on El Niño evolution through changes inteleconnection patterns between the Indian and Pacific Oceans

Revisiting the possible links between the Quasi-Biennial Oscillation and the Indian summer monsoon using NCEP R-2 and CMAP fields

International audienceIn the past the stratospheric Quasi-Biennial Oscillation (QBO) has sometimes been proposed toexplain the tendency for the Indian Summer Monsoon (ISM) to alternate between strong andweak years. In this study, NCEP Reanalysis-2 and CMAP fields are statistically analyzed toassess the relationship between equatorial zonal winds in the stratosphere and ISM. In a firststep, it is shown that zonal winds at 15hPa during the preceding winter (January-February) arethe best stratospheric predictor of the summer rainfall over the Indian subcontinent as a whole.This relationship mainly holds for August and September, or the late ISM. Surprisingly, theQBO pattern is not significantly associated with the rainfall variability during June-July or theearly ISM. CMAP and NCEP R-2 fields corroborate these findings and show that westerlyQBO years are associated with a deepening of the monsoon trough over the Gangetic plainsand decreased convective activity in the eastern equatorial Indian region. However, furtherstatistical analysis shows that the QBO-ISM link is complex since a westerly QBO phase at 15hPa in boreal winter leads to a weaker monsoon surface circulation with, in particular, aweakening of the Somali Jet at the beginning of the monsoon, but a much stronger circulationin September. At that time, the Tibetan High is reinforced, the tropical easterly jet at 200 hPa isstronger over India and the local reversed Hadley circulation is also strengthened north of theequator. The mechanisms by which the QBO may affect ISM have been explored through inparticular correlations between stratospheric winds and tropopause temperature and pressurefields. Our results provide support for an out of phase behavior of convective activity betweenthe Indian sub-continent and the equatorial Indian Ocean induced by the QBO phase, especiallyduring the late ISM. During a westerly QBO phase, convective activity is, in September,enhanced over India, which brings higher precipitation, compared to the east phase. This work also suggests that the winter QBO at 15 hPa could have some skill in foreshadowing the late ISM

Turbulent transport in the outer region of rough-wall open-channel flows: the contribution of large coherent shear stress structures (LC3S)

Acoustic Doppler velocity profiler (ADVP) measurements of instantaneous three-dimensional velocity profiles over the entire turbulent boundary layer height, δ, of rough-bed open-channel flows at moderate Reynolds numbers show the presence of large scale coherent shear stress structures (called LC3S herein) in the zones of uniformly retarded streamwise momentum. LC3S events over streamwise distances of several boundary layer thicknesses dominate the mean shear dynamics. Polymodal histograms of short streamwise velocity samples confirm the subdivision of uniform streamwise momentum into three zones also observed by Adrian et al. (J. Fluid Mech., vol. 422, 2000, p. 1). The mean streamwise dimension of the zones varies between 1δ and 2.5δ. In the intermediate region (0.2<z/δ<0.75), the contribution of conditionally sampled u'w' events to the mean vertical turbulent kinetic energy (TKE) flux as a function of threshold level H is found to be generated by LC3S events above a critical threshold level Hmax for which the ascendant net momentum flux between LC3S of ejection and sweep types is maximal. The vertical profile of Hmax is nearly constant over the intermediate region, with a value of 5 independent of the flow conditions. Very good agreement is found for all flow conditions including the free-stream shear flows studied in Adrian et al. (2000). If normalized by the squared bed friction velocity, the ascendant net momentum flux containing 90% of the mean TKE flux is equal to 20% of the shear stress due to bed friction. In the intermediate region this value is nearly constant for all flow conditions investigated herein. It can be deduced that free-surface turbulence in open-channel flows originates from processes driven by LC3S, associated with the zonal organization of streamwise momentum. The good agreement with mean quadrant distribution results in the literature implies that LC3S identified in this study are common features in the outer region of shear flow

Claude Meillassoux (1925-2005)

Claude Meillassoux nous a quittés, et avec lui c’est un moment essentiel de l’anthropologie française qui disparaît. Beaucoup d’anthropologues de ma génération s’accorderont avec moi pour le dire : Claude Meillassoux emporte avec lui toute une partie de nos vies. Comme la plupart d’entre nous, je l’ai rencontré au début des années 1960. Il était notre aîné, et il s’était déjà imposé à notre attention par ces deux écrits fondateurs que furent son article des Cahiers d’Études africaines sur l’é..

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RésuméAprès avoir dressé un « état des lieux » de l’anthropologie française au début des années 1960, l’auteur évoque les principales étapes de son parcours de chercheur : son travail en pays dida, puis en pays abron. Il rappelle quelles étaient alors les orientations dominantes : histoire, économie, politique, et quels furent à ses yeux les principaux acquis de la période. Il s’interroge pour conclure sur la situation actuelle de la discipline.AbstractAfter drawing up an “inventory” of French anthropology in the early 1960s, the author looks at the main stages of his career as a researcher and his work among the Dida and the Abron. He looks back at the main historical, economic and political trends, and what he considers to be the main lessons of that period. He concludes by reflecting on the present situation of anthropology