A spatio-temporal study of rheo-oscillations in a sheared lamellar phase using ultrasound

We present an experimental study of the flow dynamics of a lamellar phase sheared in the Couette geometry. High-frequency ultrasonic pulses at 36 MHz are used to measure time-resolved velocity profiles. Oscillations of the viscosity occur in the vicinity of a shear-induced transition between a high-viscosity disordered fluid and a low-viscosity ordered fluid. The phase coexistence shows up as shear bands on the velocity profiles. We show that the dynamics of the rheological data result from two different processes: (i) fluctuations of slip velocities at the two walls and (ii) flow dynamics in the bulk of the lamellar phase. The bulk dynamics are shown to be related to the displacement of the interface between the two differently sheared regions in the gap of the Couette cell. Two different dynamical regimes are investigated under applied shear stress: one of small amplitude oscillations of the viscosity ($\delta\eta/\eta\simeq 3$%) and one of large oscillations ($\delta\eta/\eta\simeq 25$%). A phenomenological model is proposed that may account for the observed spatio-temporal dynamicsComment: 16 pages, 17 figures, submitted to Eur. Phys. J.

The Marginal Cost of Natural Gas Distribution Pipelines: The Case of Société en Commandite Gaz Métropolitain, Québec

Investment expenditures in natural gas distribution pipelines account for 70% of the rate base of Société en Commandite Gaz Métropolitain (SCGM), the natural gas utility which serves most customers in the province of Québec. In allocating these costs to rate payers, the regulatory process divides costs into an access fee which reflects the fixed costs of planning and implementing the system that is to be divided equally over all users and a user or variable cost fee reflecting the capacity they use. In this paper we estimated a cost function to provide information to regulators on how these tariffs should be set. We use a unique data set of 131 observations which represent natural gas extension projects realized by SCGM in four Québec regions (Trois-Rivières, Sherbrooke, Québec and Chicoutimi) in the eighties and early nineties, to analyze the main determinants of capital costs. It is found that capital cost is not separable into a fixed and a variable component, that the elasticity with respect to maximum daily demand is not significant, and that the elasticity with respect to pipe length is slightly less than one. Maximum daily demand by each consumer class and consumer density per kilometer play no statistically significant role.

Light scattering from cold rolled aluminum surfaces

We present experimental light scattering measurements from aluminum surfaces obtained by cold rolling. We show that our results are consistent with a scale invariant description of the roughness of these surfaces. The roughness parameters that we obtain from the light scattering experiment are consistent with those obtained from Atomic Force Microscopy measurements

Knowledge management and history

Capitalisation of the history of a technology, a technique or a concept within an industrial company is relevant to historians. However it largely exceeds the historical problems from a Knowledge Management point of view. In this context, it can be the subject of specific approaches especially Knowledge Engineering. However, it faces two types of difficulties: - The techniques in History have few modelling tools, and are even rather reticent with the use of such tools. - Knowledge Engineering doesn't often address historical knowledge modelling, for tracing knowledge evolution. It is however possible to develop robust and validated methods, tools and techniques which take into account these two approaches, which, if they function in synergy, appear rich and fertile.History, MASK, Knowledge management, Knowledge engineering, History of techniques

An Exploration of Middle and High School Students\u27 Perceptions of Deviant Behavior When Using Computers and the Internet.

If the current trend continues, the use of computer technologies and the Internet will increase for teaching and education. It is urgent that researchers study computer and Internet deviance. The purpose of this study was to explore middle and high school students\u27 perceptions of deviant behavior when using computers and the Internet. The target population for this study was middle and high school students. The accessible population included all students who attended a middle or high school in the East Baton Rouge Parish School which has computers that are capable of accessing the Internet (1,150 students---575 middle school students and 575 high school students). The instrument used in this study was designed by Professor San-Yi Li of Taiwan. This instrument contained 66 questions and a scantron was used to record participants\u27 responses. From the instrument, variables were selected from five sections (1) students\u27 demographic characteristics; (2) computer-related activities; (3) students\u27 perceptions of deviant behavior when using computers and the Internet; (4) students\u27 perception of their peers\u27 deviant behavior when using computers and the Internet; (5) students\u27 ability to use computers and the Internet. Results showed that the majority of students\u27 indicated they perceive their behavior as being not deviant when using computers and the Internet. Contrarily students indicated they perceive the behavior of their peers to more deviant when computers and the Internet. When the means of the Students\u27 Behavior Score Peer Behavior Score were compared, there was a significant different between the scores. The Peer Behavior Score for deviance was much higher than the Student Behavior Score

Transparency_2

International audienceIn robotics and teleoperation, the paradigm of transparency seeks at evaluating the identity of the mechanical manipulation chain as compared to the electrified, decomposed. In VR, the usual understanding of the concept of transparency can be viewed an extension of the transparency in real-real teleoperation

The project of Zone Atelier Pyrenees-Garonne (ZA PYGAR)

South-Western France, going from the Pyrenees mountains to the plains of the Garonne river basin. PYGAR tries to answer three main scientific questions: 1/ What are the respective contributions of climate change and local anthropogenic disturbances to ecosystem changes (biodiversity, bio-physical characteristics)? 2/ How human practices drive ecosystem services? 3/ What are the relationships between resources availability and their accessibility, and the historic and prehistoric human population structure? The main transversal question of PYGAR is the adaption and response time of the different SES to global changes. The SES are studied at different time scales from the last glacial maximum to the present-day. PYGAR clusters 17 Labs (40 full-time permanent staffs: 23 researchers/professors & 17 engineers/technicians) from Toulouse and Bordeaux, supported by the University of Toulouse and several French research organisms (CNRS, INRA, IRSTEA, IRD, CNES, BRGM, Météo France). Socioeconomic partners (companies, farmer’s associations…) and public services (Occitania Region, Water Agency…) are strongly interested in the project. PYGAR includes 4 territories (sites ateliers): the central Pyrenees mountain range, the Garonne River, the agricultural hills and valleys of the Gascogne region and the Viaur-Aveyron river basin. The theory of SES provides a valuable tool to set up an interdisciplinary approach to deal with the co-evolution and resilience of the social and ecological templates of the studied systems facing global changes (climate change and land cover)

Discriminating small wooded elements in rural landscape from aerial photography: a hybrid pixel/object-based analysis approach

While small, fragmented wooded elements do not represent a large surface area in agricultural landscape, their role in the sustainability of ecological processes is recognized widely. Unfortunately, landscape ecology studies suffer from the lack of methods for automatic detection of these elements. We propose a hybrid approach using both aerial photographs and ancillary data of coarser resolution to automatically discriminate small wooded elements. First, a spectral and textural analysis is performed to identify all the planted-tree areas in the digital photograph. Secondly, an object-orientated spatial analysis using the two data sources and including a multi-resolution segmentation is applied to distinguish between large and small woods, copses, hedgerows and scattered trees. The results show the usefulness of the hybrid approach and the prospects for future ecological applications

M-lines characterization of selenide and telluride waveguides for mid-infrared interferometry

Nulling interferometry is an astronomical technique that combines equal wavefronts to achieve a deep rejection ratio of an on-axis star, and that could permit to detect Earth-like planets in the mid-infrared band 5 -- 20 microns. Similarly to what is done in the near-infrared, high frequencies spatial filtering of the incoming beams can be achieved using single-mode waveguides operating in the mid-infrared. An appreciable reduction of the instrumental complexity is also possible using integrated optics (IO) devices in this spectral range. The relative lack of single-mode guided optics in the mid-infrared has motivated the present technological study to demonstrate the feasibility of dielectric waveguides functioning at longer wavelengths. We propose to use selenide and telluride components to pursue the development of more complex IO functions.Comment: accepted in OSA Optics Express, 11 pages, 4 figure