New image processing tools for structural dynamic monitoring

This paper presents an introduction to structural damage assessment using image processing on real data (non ideal conditions). Our contribution is much more a groundwork than a classical experimental validation. After measuring the bridge dynamic parameter on a small resolution video, we conjointly present advantages and limitations of our method. Finally we introduce several "computer vision" based rules and focus on the technical ability to detect damage using camera and video motion estimation

Large-scale bottleneck effect in two-dimensional turbulence

The bottleneck phenomenon in three-dimensional turbulence is generally associated with the dissipation range of the energy spectrum. In the present work, it is shown by using a two-point closure theory, that in two-dimensional turbulence it is possible to observe a bottleneck at the large scales, due to the effect of friction on the inverse energy cascade. This large-scale bottleneck is directly related to the process of energy condensation, the pile-up of energy at wavenumbers corresponding to the domain size. The link between the use of friction and the creation of space-filling structures is discussed and it is concluded that the careless use of hypofriction might reduce the inertial range of the energy spectrum

Hydraulic Modeling of a Mixed Water Level Control Hydromechanical Gate

This article describes the hydraulic behavior of a mixed water level control hydromechanical gate present in several irrigation canals. The automatic gate is termed "mixed" because it can hold either the upstream water level or the downstream water level constant according to the flow conditions. Such a complex behavior is obtained through a series of side tanks linked by orifices and weirs. No energy supply is needed in this regulation process. The mixed flow gate is analyzed and a mathematical model for its function is proposed, assuming the system is at equilibrium. The goal of the modeling was to better understand the mixed gate function and to help adjust their characteristics in the field or in a design process. The proposed model is analyzed and evaluated using real data collected on a canal in the south of France. The results show the ability of the model to reproduce the function of this complex hydromechanical system. The mathematical model is also implemented in software dedicated to hydraulic modeling of irrigation canals, which can be used to design and evaluate management strategies

The Parallel Meaning Bank: Towards a Multilingual Corpus of Translations Annotated with Compositional Meaning Representations

The Parallel Meaning Bank is a corpus of translations annotated with shared, formal meaning representations comprising over 11 million words divided over four languages (English, German, Italian, and Dutch). Our approach is based on cross-lingual projection: automatically produced (and manually corrected) semantic annotations for English sentences are mapped onto their word-aligned translations, assuming that the translations are meaning-preserving. The semantic annotation consists of five main steps: (i) segmentation of the text in sentences and lexical items; (ii) syntactic parsing with Combinatory Categorial Grammar; (iii) universal semantic tagging; (iv) symbolization; and (v) compositional semantic analysis based on Discourse Representation Theory. These steps are performed using statistical models trained in a semi-supervised manner. The employed annotation models are all language-neutral. Our first results are promising.Comment: To appear at EACL 201

Time-reversibility of Navier-Stokes turbulence and its implication for subgrid scale models

Among existing subgrid scale models for large-eddy simulation (LES) some are time-reversible in the sense that the dynamics evolve backwards in time after a transformation $\bm u \rightarrow -\bm u$ at every point in space. In practice, reversible subgrid models reduce the numerical stability of the simulations since the effect of the subgrid scales is no longer strictly dissipative. This lack of stability constitutes often a criterion to reject this kind of models. The aim of this paper is to examine whether time-reversibility can constitute a criterion that a subgrid model has to fulfill, or has not to. Thereto we investigate by direct numerical simulation the time-dependence of the kinetic energy of the resolved scales when the velocity is reversed in all or part of the lengthscales of the turbulent flow. These results are compared with results from existing LES subgrid models. It is argued that the criterion of time-reversibility to assess subgrid models is incompatible with the main underlying assumption of LES.Comment: Journal of Turbulence (2012) 1-

Analysis and Optimization of Cryptographically Generated Addresses

The need for nodes to be able to generate their own address and verify those from others, without relying on a global trusted authority, is a well-known problem in networking. One popular technique for solving this problem is to use self-certifying addresses that are widely used and standardized; a prime example is cryptographically generated addresses (CGA). We re-investigate the attack models that can occur in practice and analyze the security of CGA-like schemes. As a result, an alternative protocol to CGA, called CGA++, is presented. This protocol eliminates several attacks applicable to CGA and increases the overall security. In many ways, CGA++ offers a nice alternative to CGA and can be used notably for future developments of the Internet Protocol version 6

Procoagulant Adaptation of a Blood Coagulation Prothrombinase-like Enzyme Complex in Australian Elapid Venom

The macromolecular enzyme complex prothrombinase serves an indispensable role in blood coagulation as it catalyzes the conversion of prothrombin to thrombin, a key regulatory enzyme in the formation of a blood clot. Interestingly, a virtually identical enzyme complex is found in the venom of some Australian elapid snakes, which is composed of a cofactor factor Va-component and a serine protease factor Xa-like subunit. This review will provide an overview of the identification and characterization of the venom prothrombinase complex and will discuss the rationale for its powerful procoagulant nature responsible for the potent hemostatic toxicity of the elapid venom

Die Weltwirtschaft im Wandel: Symposium 1975

Seit einigen Jahren verstärkt sich der Eindruck, daß die Weltwirtschaft in einem raschen Wandel begriffen ist. Die Entwicklungsländer fordern eine neue Weltwirtschaftsordnung. Auf die weltweite Hochkonjunktur ist eine scharfe und recht lange anhaltende Rezession gefolgt; aber noch immer dominieren inflationäre Tendenzen. Den Konjunktureinbruch überlagert hat die Vervielfachung des Ölpreises Ende 1973. Sie wurde von vielen Beobachtern als Beginn einer Phase mit zunehmendem Rohstoffmangel und nie gekannten Ungleichgewichten in den Zahlungsbilanzen gedeutet. Von den vielfach geäußerten Befürchtungen haben sich manche als übertrieben erwiesen; denn viele Schwierigkeiten konnte der Markt viel besser als erwartet und ziemlich geräuschlos bewältigen. Gleichwohl erscheint es geraten, die alten und die neuen Probleme der Weltwirtschaft ständig zu beobachten. Vom 23. -27. Juni, traf sich in Kiel eine Gruppe unabhängiger Ökonomen aus Japan, Nordamerika und der Europäischen Gemeinschaft in der Absicht, die Situation der Weltwirtschaft zu analysieren und Vorschläge für wirtschaftspolitische Maßnahmen auf nationaler und internationaler Ebene auszuarbeiten. Das Institut für Weltwirtschaft war Gastgeber. Das Kieler Symposium ist ein Glied in einer Reihe trilateraler Konferenzen über weltwirtschaftliche Fragen, die von der Brookings Institution in Washington, dem Japan Economic Research Center in Tokio und dem Institut für Weltwirtschaft gemeinsam veranstaltet werden. Die Ergebnisse werden jeweils in englischer, japanischer und deutscher Sprache veröffentlicht; frühere Berichte in der deutschen Fassung sind als Kieler Diskussionsbeiträge Nr. 31 "Welthandel und Strukturanpassung in den Industrieländern" und Nr. 36 "Weltrohstoffversorgung: Konflikt oder Kooperation?" erschienen