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Critical Power (critical + power)

Distribution by Scientific Domains

Humanities and Social Sciences	33%

Selected Abstracts

Prediction method of critical power by film flow rate measurement and subchannel analysis

HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 5 2005
Miyuki Akiba
Abstract This paper presents a method that can estimate the critical power of boiling water reactors, BWRs, with regard to spacer geometry. The current experimental method for estimating the critical power for BWR design requires many trained experts and expensive facilities to conduct the experiments. In the present method, the liquid film flow rate of adiabatic gas-liquid two-phase flow and a subchannel analysis of the actual BWR flow condition are measured experimentally and analyzed. In the experiment, deposition enhancement coefficients of three spacer geometries,a ferrule, an egg-crate, and a ferrule spacer with twisted tape (CYCLONE spacer),were estimated by measuring the liquid film flow rate of air-water two-phase flow flowing up in a vertical square (4 × 4) rod bundle that simulated the rod bundle of a BWR. Using these coefficients, the critical powers for bundles using each type of spacer geometry were calculated in the subchannel analysis. This method was validated using previous critical power data in the actual BWR flow condition. The critical powers predicted by this method agreed well with those of the experimental data. The result confirmed the effectiveness of this experiment-simulation combined method, as well as the advantage over current experimental methods in terms of human and facility costs. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(5): 309,323, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20069 [source]

Exodus as Travelling Theory: Excavating the Promised Land in the African American Imagination

LITERATURE COMPASS (ELECTRONIC), Issue 3 2007
Anna Hartnell
This essay won the 2006 Literature Compass Graduate Essay Prize, American Section. Exodus, this article suggests, is one of the defining texts through which Americans have imaginatively re-mapped the nation's relationship to the spectre of ,Egyptian' oppression. This article proposes to consider the evolution of the Exodus text from its pivotal place in an often imperialist presidential rhetoric to its central position in African American elaborations of resistance. I suggest that the story of Exodus issuing from the lips of W. E. B. Du Bois, Martin Luther King or Toni Morrison crucially unsettles the ,innocent' position assumed by America's political establishment in relation to the enigmatic question of ,freedom'. This article reviews the interruptive possibilities of African American re-tellings of the Exodus narrative in the context of Edward Said's notion of ,travelling theory'. In his examination of theories devolved from their point of origin, Said poses a crucial distinction between theories that lose their critical power via domestication to the status quo and those which ,flame out' from this path by reaffirming and even furthering their radical potential. I argue here that it is these destablizing currents that largely animate the African American counter-cultural tradition that excavates the promised land in order to tell of a fundamentally ,unhomely' exodus. Where mainstream invocations of Exodus present America's rendition as an epochal overcoming of Hegel's seemingly inexorable master/slave dialectic, the appropriation of this story by America's internal ,others' is a standing reminder that America is not , contra Hegel's memorable suggestion , the destination of ,History's' end. [source]

Critical Theory and its Practices: Habermas, Kosovo and International Relations

POLITICS, Issue 3 2008
Naomi Head
Developing the ,applied turn' in critical theory and Habermasian discourse ethics, this article explores whether a communicative ethics approach enables us to examine the justifications for and legitimacy of actions taken by states during NATO's intervention in Kosovo. By focusing on the deliberations which took place in the UN Security Council over Kosovo from March 1998 to June 1999 and the negotiations at Rambouillet in 1999, it will be shown that there are patterns of exclusion, coercion and illegitimacy which not only challenge the claims to legitimacy of the intervention and of the interveners, but indicate the critical power of a communicative framework. [source]

Robustness of a 3 min all-out cycling test to manipulations of power profile and cadence in humans

EXPERIMENTAL PHYSIOLOGY, Issue 3 2008
Anni Vanhatalo
The purpose of this study was to assess whether end-test power output (EP, synonymous with ,critical power') and the work done above EP (WEP) during a 3 min all-out cycling test against a fixed resistance were affected by the manipulation of cadence or pacing. Nine subjects performed a ramp test followed, in random order, by three cadence trials (in which flywheel resistance was manipulated to achieve end-test cadences which varied by ,20 r.p.m.) and two pacing trials (30 s at 100 or 130% of maximal ramp test power, followed by 2.5 min all-out effort against standard resistance). End-test power output was calculated as the mean power output over the final 30 s and the WEP as the power,time integral over 180 s for each trial. End-test power output was unaffected by reducing cadence below that of the ,standard test' but was reduced by ,10 W on the adoption of a higher cadence [244 ± 41 W for high cadence (at an end-test cadence of 95 ± 7 r.p.m.), 254 ± 40 W for the standard test (at 88 ± 6 r.p.m.) and 251 ± 38 W for low cadence (at 77 ± 5 r.p.m.)]. Pacing over the initial 30 s of the test had no effect on the EP or WEP estimates in comparison with the standard trial. The WEP was significantly higher in the low cadence trial (16.2 ± 4.4 kJ) and lower in the high cadence trial (12.9 ± 3.6 kJ) than in the standard test (14.2 ± 3.7 kJ). Thus, EP is robust to the manipulation of power profile but is reduced by adopting cadences higher than ,standard'. While the WEP is robust to initial pacing applied, it is sensitive to even relatively minor changes in cadence. [source]