3,919 research outputs found
Fabrication of an in-plane SU-8 cantilever with integrated strain gauge for wall shear stress measurements in fluid flows.
We present a cantilever fabricated from the polymer SU-8 for the measurement of wall shear stress in fluid flows. The pressure induced deflection of the cantilever, measured using a calibrated and integrated nichrome strain gauge, can be related to the wall shear stress on the surface. The initial degree of curvature of the cantilever can be controlled via the exposure dose, which allows a small positive deflection to be achieved, and so minimises the intrusion into the flow. Wind tunnel testing results show a sensitivity greater than 2.5 mV/Pa, with a shear stress of 0.38 Pa and excitation of 1 V
ESTIMATING THE STOCK OF GLASS EELS IN AN ESTUARY BY MARK-RECAPTURE EXPERIMENTS USING VITAL DYES
Glass eels (Anguilla anguilla) arriving after the fishing season in the Vilaine estuary (France) were caught by boat and at a trapping ladder located at a blocking dam upstream in the estuary. They were marked with Bismarck brown, rhodamine B or neutral red, and released into the estuary. The effect of marking on behaviour, mortality and recapture differed according to the dye and concentration used. The glass eels also differed in response to marking according to their origin. Estuarine glass eels were clearly desynchronized in their selective tidal stream transport and left the release area after a few tidal cycles. Trapped glass eels were less sensitive to marking. They remained in the release area and were recaptured in larger number both in the trapping ladder and in the estuary. These results supported a model of two behavioral fractions in the estuary: flow-carried migrants and active glass eels with stronger rheotactic behaviour. The proportion of active glass eels in the estuary shifted from none for the two weeks after the fishery closure, to 10% value of the total stock. At the trapping ladder, the migration ended in June each year, while a large stock was still present in the estuary. These observations favour the interpretation of a short duration of the active phase at this site followed by the transition towards a more benthic behavior. The daily efficiency of the trapping ladder was calculated as 4% of the active stock from both stock estimations and average recapture rate. This value was consistent with the low annual efficiency of the trapping ladder, calculated as 30% of the estuarine stock of glass eels that arrived after the fishing season
Quadratic BSDEs driven by a continuous martingale and application to utility maximization problem
In this paper, we study a class of quadratic Backward Stochastic Differential
Equations (BSDEs) which arises naturally when studying the problem of utility
maximization with portfolio constraints. We first establish existence and
uniqueness results for such BSDEs and then, we give an application to the
utility maximization problem. Three cases of utility functions will be
discussed: the exponential, power and logarithmic ones
Une synthèse des modèles de représentation des connaissances à base de Graphes Conceptuels et OWL
Nous présentons et comparons deux approches de modélisation, formelles et concrètes, pour représenter et manipuler des connaissances d’un domaine. Le modèle des graphes conceptuels permet de modéliser des connaissances en terme de graphes, basés sur un support. Cette approche de modélisation est intensionnelle, est munie d’une sémantique en logique du premier ordre, et fait l’hypothèse d’un monde fermé pour ses raisonnements. Le langage OWL permet de décrire des ontologies et des faits sur le Web, suivant une approche de modélisation extensionnelle. Il possède une sémantique issue des logiques de descriptions, et fait l’hypothèse d’un monde ouvert pour ses raisonnements
SafeSlice: A model slicing and design safety inspection tool for SysML
Software safety certification involves checking that the software design meets the (software) safety requirements. In practice, inspections are one of the primary vehicles for ensuring that safety requirements are satisfied by the design. Unless the safety-related aspects of the design are clearly delineated, the inspections conducted by safety assessors would have to consider the entire design, although only small fragments of the design may be related to safety. In a model-driven development context, this means that the assessors have to browse through large models, understand them, and identify the safety-related fragments. This is time-consuming and error-prone, specially noting that the assessors are often third-party regulatory bodies who were not involved in the design. To address this problem, we describe in this paper a prototype tool called, SafeSlice, that enables one to automatically extract the safety-related slices (fragments) of design models. The main enabler for our slicing technique is the traceability between the safety requirements and the design, established by following a structured design methodology that we propose. Our work is grounded on SysML, which is being increasingly used for expressing the design of safety-critical systems. We have validated our work through two case studies and a control experiment which we briefly outline in the paper. © 2011 ACM
Analytical solution of a model for complex food webs
We investigate numerically and analytically a recently proposed model for
food webs [Nature {\bf 404}, 180 (2000)] in the limit of large web sizes and
sparse interaction matrices. We obtain analytical expressions for several
quantities with ecological interest, in particular the probability
distributions for the number of prey and the number of predators. We find that
these distributions have fast-decaying exponential and Gaussian tails,
respectively. We also find that our analytical expressions are robust to
changes in the details of the model.Comment: 4 pages (RevTeX). Final versio
Zinc Oxide Nanowires Deposited on Polymeric Hotplates for Low-power Gas Sensors
Zinc oxides (ZnO) nanowires were successfully deposited on plastic low-power micro-hotplates using the thermal oxidation technique. Metallic zinc layer was deposited on the sensing transducer by RF magnetron sputtering and then oxidized in a controlled atmosphere in order to obtain ZnO nanostructures. Morphological investigations confirmed the nanometric dimensions of the fabricated nanostructures. The n-type behavior of the nanostructured material was evaluated towards different chemical species to highlight the electrical properties of the materials. Calibration curves for the detection of several chemical species were defined. © 2012 The Authors. Published by Elsevier Ltd
Bis(μ-diethylphosphido-κ2 P:P)bis[bis(2,4,6-trimethylphenyl)indium(III)]
The title compound, [In2(C9H11)4(C4H10P)2], contains a centrosymmetric In2P2 core with short intermolecular In—P bonds. This core has acute P—In—P and obtuse In—P—In bond angles compared with other [R
2InPR′2]2 analogues, due to the presence of the bulky aromatic substituents on the In atom and the non-sterically demanding ethyl substituents on the P atom
A bipartite class of entanglement monotones for N-qubit pure states
We construct a class of algebraic invariants for N-qubit pure states based on
bipartite decompositions of the system.
We show that they are entanglement monotones, and that they differ from the
well know linear entropies of the sub-systems. They therefore capture new
information on the non-local properties of multipartite systems.Comment: 6 page
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