Off-design considerations through the properties of some pressure-ratio line of radial inflow turbines

Radial turbines are commonly used in applications involving operation through severe off-design conditions. The emergence of variable-geometry systems leads to the distinction between two off-design concepts: operational and geometric off-designs. Both of these operating constraints should be integrated in the design procedure. Recent developments in prediction and optimization methods allowed such an integration, but involving complex algorithms is coupled with semiempiric loss models. This paper provides a basis to obtain simple information from an existing or predesigned machine, for both operational and geometric offdesign conditions. An alternative turbine map is defined using loading and flow coefficients. A one-dimensional analysis shows that the constant pressure-ratio lines are straight lines whose slope is remarkably correlated with the pressure-ratio value and geometrical characteristics. This theoretical approach is validated against the experimentation of two machines, the linearity is observed in both cases. The direct influence of the stator configuration on the pressure-ratio lines confirms the applicability of this work to variable-geometry stages. A dimensionless cross-section of the stator is thus defined. However, the unexpected displacement of the intercept of the pressure-ratio lines limits the application field of this method. Nevertheless, a simple performance prediction analysis is proposed for blocked mass flow operation

Probing a critical length scale at the glass transition

We give evidence of a clear structural signature of the glass transition, in terms of a static correlation length with the same dependence on the system size which is typical of critical phenomena. Our approach is to introduce an external, static perturbation to extract the structural information from the system's response. In particular, we consider the transformation behavior of the local minima of the underlying potential energy landscape (inherent structures), under a static deformation. The finite-size scaling analysis of our numerical results indicate that the correlation length diverges at a temperature $T_c$, below the temperatures here the system can be equilibrated. Our numerical results are consistent with random first order theory, which predicts such a divergence with a critical exponent $\nu=2/3$ at the Kauzmann temperature, where the extrapolated configurational entropy vanishes.Comment: 5 pages, 5 figures, to appear in Phys. Rev. Lett. 2010

A Text Collage

Starting from a fishbowl discussion which has taken place at the conference, this paper discusses what can be gained from thinking across genderqueer theories and anthropological Europeanization research. It argues that thinking queerly includes a skepticism towards identitarian and normative understandings of Europe, as well as an ethnographic attention to that which emerges in the gaps and cracks of Europeanization, while keeping in mind the ways in which institutions working in the name of Europe generate heterogeneous experiences resulting in unequal and differentially distributed, multiple Europes. ‘Queering Europe’ oscillates between an emphasis on the central role of the sexual and the gendered in imaginations of Europe and destabilizing notions of Europe in a more general sense and is as such closely related to post-/decolonial approaches. This analytical move has three dimensions to it: Firstly, queering Europe aims at deconstructing hegemonic imaginaries of Europe. Secondly, it makes visible the pluralistic and fragmented nature of Europe(s) and the ambivalent and sometimes unforeseen consequences processes of Europeanization are accompanied by. Thirdly, queering Europe can be envisioned as a way of imagining and thinking Europe through a “critical utopianism” (Mbembe 2019) that puts solidarity center stage. In all three dimensions, an ethnography informed by decolonial critiques as well as by proposals for queering methodologies constitutes our chosen epistemological tool to gain deeper insights into queering Europe as a mode of knowledge production and political vision.Ausgehend von einer Fish-Bowl-Diskussion, die während der Konferenz stattfand, diskutieren wir in unserem Beitrag, was durch ein Denken zwischen gender_queer Theorien und anthropologischer Europäisierungsforschung gewonnen werden kann. Wir argumentieren, dass queeres Denken eine Skepsis gegenüber identitären und normativen Verständnissen von Europa beinhalten muss sowie eine ethnographische Aufmerksamkeit dafür, was in den Lücken und Rissen der Europäisierung auftaucht. Gleichzeitig gilt es im Auge zu behalten, wie Institutionen, die im Namen Europas arbeiten, heterogene Erfahrungen erzeugen, die zu ungleichen und unterschiedlich verteilten, multiplen Europas führen. Insofern korrespondiert dieser Zugang mit post-/dekolonialen Ansätzen in der Anthropologie. Queering Europe oszilliert zwischen einer Aufmerksamkeit für die zentrale Rolle, die Sexualität und Geschlecht in den Imaginarien von Europa spielen, und der Destabilisierung von Vorstellungen von Europa in einem allgemeineren Sinn. Drei Dimensionen dieses analytischen Ansatzes werden diskutiert: Erstens zielt queering Europe darauf ab, hegemoniale Vorstellungen von Europa zu dekonstruieren; zweitens macht es den multiplen und fragmentierten Charakter Europas sowie die ambivalenten und manchmal unvorhersehbaren Konsequenzen sichtbar, die Europäisierungsprozesse mit sich bringen; und drittens kann queering Europe als Möglichkeit gesehen werden, Europa durch die Linse eines "kritischen Utopismus" (Mbembe 2019) zu betrachten und Solidarität in den Mittelpunkt der Überlegungen zu stellen. In allen drei Dimensionen stellt ethnographisches Arbeiten, das von dekolonialen Kritiken sowie von Vorschlägen zum Queeren von Methoden geprägt ist, das erkenntnistheoretische Werkzeug dar, um tiefere Einblicke in queering Europe als eine Art der Wissensproduktion wie der politischen Vision zu erhalten.Peer Reviewe

Non-affine deformations of inherent structure as signature of cooperativity in supercooled liquids

We unveil the existence of non-affinely rearranging regions in the inherent structures (IS) of supercooled liquids by numerical simulations of two- and three-dimensional model glass formers subject to static shear deformations combined with local energy minimizations. In the liquid state IS, we find a broad distribution of rather large rearrangements which are correlated only over small distances. At low temperatures, the onset of the cooperative dynamics corresponds to much smaller displacements correlated over larger distances. This finding indicates the presence of non-affinely rearranging domains of relevant size in the IS deformation, which can be seen as the static counterpart of the cooperatively rearranging regions in the dynamics. This idea provides new insight into possible structural signatures of slow cooperative dynamics of supercooled liquids and supports the connections with elastic heterogeneities found in amorphous solids.Comment: 4 pages, 3 figures, revised version + auxiliary material, to appear in Phys. Rev. Let