Mechanical Performance Of A Two Stage Centrifugal Compressor Under Wet Gas Conditions

Lecturepg. 121-128As subsea compression becomes a vital technology to the successful production of gas reserves in the North Sea, several technology issues will come to the forefront of the oil and gas industry. One of these important subjects is the capability to compress gas which includes a significant amount of liquids. Compressing wet gas requires knowledge in areas such as the prediction of turbomachinery performance with the mixed phase flow as well as the mechanical reliability of machinery in the same environment. This paper presents experimental results from a wet gas test campaign which, among other goals, is focused on characterizing the mechanical performance of a two stage compressor operating under wet gas conditions. Various mechanical parameters are monitored in the test program including rotor radial and axial vibration, rotor thrust, and shaft torque. A full array of wet gas conditions are tested with a suction pressure of 20 bar (300 psia) and liquid volume fractions in the range of 0.5 to 5%. The operating fluids are air and water, and the two stage compressor is operated at three speed lines ranging from high flow to low flow conditions. Significant variations are noted in the axial thrust, axial vibration and shaft torque. Thrust variations range from seemingly neutral thrust conditions at very low water injection rates to significant thrust increases (as compared to dry condition) for very high water injection rates. Rotor axial vibration is characterized by large amplitude and very low frequency, especially for the case in which the rotor thrust is balanced by the water injection. During higher levels of water injection, rotor axial vibration is generally characterized by relatively large amplitude and slightly higher frequency, although still very low as a percent of running speed. Variations in radial vibration are also noted, but to a much lesser extent

La democrazia in un ambiente ostile: Un quasi esperimento deliberativo

In this article, we present the results of a deliberative polling experiment conducted in March 2007 with a sample of inhabitants of the province of Turin on two issues: the high-speed train connecting France to Italy (TAV) and the right to vote for legal non-EU immigrants in local elections. Following the standard design of deliberative poll, we report several aggregate and individual changes in attitudes. Changes in level of information and policy preferences were significant, but more limited than in comparable local deliberative polls. However, the experiment revealed another, different, set of changes in the normative and cognitive beliefs related to the legitimacy and technical merit of the arguments held by those whose ideas the respondents do not share. In particular, the views that were contrary to the prevalent climate of opinion were perceived, after the experiment, as more legitimate and more grounded in significant empirical or normative arguments than before. These results point to the importance of a deliberative environment that allows for a balanced and egalitarian discussion in which opposing arguments can be assessed and the implications of different alternatives explored in greater detail. Such an environment encourages dialogue between majority and minority over controversial issues and it fosters mutual respect among opposing parties and greater understanding of opposing views and arguments

Special Metrics and Group Actions in Geometry

This volume is a follow-up to the INdAM workshop “New perspectives in differen- tial geometry” that took place on 16–20 November 2015: https://newperspectivesindg.wordpress.com The editors are deeply grateful to the Istituto Nazionale di Alta Matematica “Francesco Severi” (INdAM) for generously sponsoring and hosting the event in Rome, and to the Institute’s President, Giorgio Patrizio, for his steadfast support. We are indebted to Diego Conti and Caterina Stoppato for the invaluable hard work in organising the workshop, and to Graziano Gentili and Andrew Swann for playing a key role on the scientific committee. We would also like to thank wholeheartedly the conference speakers: Ilka Agricola, Adrián Andrada, Vestislav Apostolov, John Armstrong, Fiammetta Battaglia, Roger Bielawski, Fran Burstall, Vicente Cortés, Johann Davidov, Paul Gauduchon, Marisa Fernández, Nigel Hitchin, Claude LeBrun, Thomas Madsen, Stefano Marchiafava, Vicente Muñoz, Paolo Piccinni, Uwe Semmelmann and Luis Ugarte. On the occasion of the workshop we celebrated the 60th birthday of Simon Salamon, a worldwide leading scholar at the forefront of research in differential geometry whose extensive body of work centres around Riemannian and com- plex manifolds defined with reference to the action of a Lie group. The unique contributions appearing in this book focus on a variety of cutting-edge topics revolving around Salamon’s interests: quaternionic and octonionic geometry, twistor spaces, almost-complex manifolds, harmonic maps, exceptional holonomy, Einstein metrics, spinors, homogeneous spaces and nilmanifolds, special geometries in dimensions 5, 6, 7 and 8, conformal geometry, moduli spaces, gauge theory, 4- manifolds, symplectic manifolds and integrable systems. Simon Salamon is Professor of Geometry at King’s College, London, and previously worked at Politecnico di Torino, Imperial College and Oxford University. The workshop was widely attended by his colleagues, friends and former students from all over the world, and this volume represents both a fitting tribute to a trailblazing force in the field and a compelling testimony to the profound and longstanding impact that Salamon has on the mathematical community. Heartfelt thanks go to the authors who accepted the invitation to publish here: Fiammetta Battaglia, Giovanni Bazzoni, Indranil Biswas, Fran Burstall, Vicente Cortés, Andrew Dancer, Johann Davidov, Malte Dyckmanns, Marisa Fernández, Paul Gauduchon, Claude LeBrun, Andrea Loi, Jason Lotay, Thomas Madsen, Andrei Moroianu, Vicente Muñoz, Antonio Otal, Paolo Piccinni, Simon Salamon, Stefan Suhr, Andrew Swann, Aleksy Tralle, Luis Ugarte, Raquel Villacampa, Dan Zaffran and Fabio Zuddas. We strongly believe these papers will be extremely relevant to the advancement of academic research and are certain they will serve generations to come

Essential oil composition of different parts of Tertaclinis articulata

The work evaluates the yield and the composition of the essential oil extracted from leafy and woody branches, cones, and seeds of a cultivated stand of Tetraclinis artfculuta (Vahl) Masters (Cupressaceae) growing in Malta. The main components were a-pinene, limonene, camphor, bornyl acetate, borneol and germacrene D. Our results show a number of differences in composition to a Moroccan study of the essential oil derived from homologous parts.peer-reviewe