Detailed extensions of perturbation methods for nonlinear panel flutter Technical report, 11 Dec. 1969 - 15 Mar. 1971

Perturbation method extension for nonlinear panel flutter to include fifth-order nonlinear terms effect, flutter-buckling interaction, and small damping term

Steady subsonic flow around finite-thickness wings

The general method for analyzing steady subsonic potential aerodynamic flow around a lifting body having arbitrary shape is presented. By using the Green function method, an integral representation for the potential is obtained. Under small perturbation assumption, the potential at any point, P, in the field depends only upon the values of the potential and its normal derivative on the surface of the body. Hence if the point P approaches the surface of the body, the representation reduces to an integral equation relating the potential and its normal derivative (which is known from the boundary conditions) on the surface. The question of uniqueness is examined and it is shown that, for thin wings, the operator becomes singular as the thickness approaches zero. This fact may yield numerical problems for very thin wings. However, numerical results obtained for a rectangular wing in subsonic flow show that these problems do not appear even for thickness ratio tau = .001. Comparison with existing results shows that the proposed method is at least as fast and accurate as the lifting surface theories

Geometry requirements for unsteady aerodynamics in aeroelastic analysis and design

Aircraft geometry requirements for unsteady aerodynamic computations are discussed and differences between requirements for steady and unsteady flow are emphasized within the framework of a general potential-flow aerodynamic formulation. Its implementation in a computer program called SOUSSA (Steady, Oscillatory, and Unsteady Subsonic and Supersonic Aerodynamic is detailed

Landslides, a Key Landform in the Global Geological Heritage

Landslides are important components of global geoheritage, but awareness of their significance and value in such terms seems scanty in the scientific community. Landslides are normally identified among various features of geological and geomorphological interest, and often considered a source of hazard. However, they are seldom identified as geosites and as part of geoheritage. This paper aims at filling these gaps by highlighting the importance of landslides in the global geoheritage. After a short introduction on the values and criteria to define landforms as geosites, based on literature review, we show to what extent landslides have been defined as geomorphosites and as part of geoheritage around the world. We then outline three aspects that should be specifically considered in the identification of landslides as geomorphosites, namely 1) past and present climate changes, 2) anthropic signature, and 3) risk perception. Finally, we describe four cases of spectacular landslides that serve as significant examples worldwide

J/psi production at RHIC-PHENIX

The J/psi is considered to be among the most important probes for the deconfined quark gluon plasma (QGP) created by relativistic heavy ion collisions. While the J/psi is thought to dissociate in the QGP by Debye color screening, there are competing effects from cold nuclear matter (CNM), feed-downs from excited charmonia (chi_c and psi') and bottom quarks, and regeneration from uncorrelated charm quarks. Measurements that can provide information to disentangle these effects are presented in this paper.Comment: 4 pages, 3 figures, conference proceedings: the 20th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions, Quark Matter 2008, Jaipur (India), 4-10 February 2008, submitted to J. Phys. G: Nuclear and Particle Physic

Long-runout landslides with associated longitudinal ridges in Iceland as analogues of Martian landslide deposits

Much work has been done to study the behaviour of long-runout landslides and their associated longitudinal ridges, yet the origin of the hypermobility of such landslides and the formation mechanism of longitudinal ridges are poorly understood. As terrestrial long-runout landslides emplaced on glaciers commonly exhibit longitudinal ridges, the presence of these landforms has been used to infer the presence of ice on Mars, where hundreds of well-preserved long-runout landslides with longitudinal ridges are found. However, the presence of the same landforms in regions where extensive glaciations did not occur, for instance, on the Moon and in the Atacama region on Earth, suggests that ice is not the only factor influencing the formation of long-runout landslides with longitudinal ridges. Iceland is a unique region for its high spatial density of well-preserved long-runout landslides with longitudinal ridges. Here, we compiled the first catalogue of Icelandic long-runout landslides with longitudinal ridges, and we compared them with Martian long-runout landslides with longitudinal ridges of similar length. Moreover, we present detailed morphological observations of the Dalvík landslide deposit, in the Tröllaskagi peninsula, Iceland, and compare them with morphological observations of Martian landslides. Our results show that Icelandic long-runout landslides share key features with Martian analogue deposits, including splitting of longitudinal ridges and development of associated en echelon features. Therefore, Icelandic long-runout landslides with longitudinal ridges represent good morphological analogues of Martian long-runout landslides. Moreover, Iceland offers an opportunity to investigate the occurrence of these landforms at a regional scale, as well as their link with deglaciation following the Last Glacial Maximum, which could also provide insights into Martian palaeoclimatic and palaeoenvironmental conditions.</p

Crystallographic disorder and electron scattering on structural two-level systems in ZrAs1.4Se0.5

Single crystals of ZrAs1.4Se0.5 (PbFCl type structure) were grown by chemical vapour transport. While their thermodynamic and transport properties are typical for ordinary metals, the electrical resistivity exhibits a shallow minimum at low temperatures. Application of strong magnetic fields does not influence this anomaly. The minimum of the resistivity in ZrAs1.4Se0.5 apparently originates from interaction between the conduction electrons and structural two-level systems. Significant disorder in the As-Se substructure is inferred from X-ray diffraction and electron microprobe studies

A magnetic internal mechanism for precise orientation of the camera in wireless endoluminal applications

Background and study aims: The use of magnetic fields to control operative devices has been recently described in endoluminal and transluminal surgical applications. The exponential decrease of magnetic field strength with distance has major implications for precision of the remote control. We aimed to assess the feasibility and functionality of a novel wireless miniaturized mechanism, based on magnetic forces, for precise orientation of the camera. Materials and methods: A remotely controllable endoscopic capsule was developed as proof of concept. Two intracapsular moveable permanent magnets allow fine positioning, and an externally applied magnetic field permits gross movement and stabilization. Performance was assessed in ex vivo and in vivo bench tests, using porcine upper and lower gastrointestinal tracts. Results: Fine control of capsule navigation and rotation was achieved in all tests with an external magnet held steadily about 15 cm from the capsule. The camera could be rotated in steps of 1.8°. This was confirmed by ex vivo tests; the mechanism could adjust the capsule view at 40 different locations in a gastrointestinal tract phantom model. Full 360° viewing was possible in the gastric cavity, while the maximal steering in the colonwas 45° in total. In vivo, a similar performance was verified, where the mechanism was successfully operated every 5 cm for 40 cm in the colon, visually sweeping from side to side of the lumen; 360° views were obtained in the gastric fundus and body, while antrally the luminal walls prevented full rotation. Conclusions: We report the feasibility and effectiveness of the combined use of external static magnetic fields and internal actuation to move small permanent intracapsular magnets to achieve wirelessly controllable and precise camera steering. The concept is applicable to capsule endoscopy as to other instrumentation for laparoscopic, endoluminal, or transluminal procedures