Determination of the fibre orientation distribution of a mineral wool network and prediction of its transverse stiffness using X-ray tomography

A method to determine the orientation and diameter distributions of mineral wool fibre networks using X-ray tomography and image analysis is presented. The method is applied to two different types of mineral wool: glass wool and stone wool. The orientation information is obtained from the computation of the structure tensor, and the diameter is estimated by applying a greyscale granulometry. The results of the image analysis indicate the two types of fibres are distributed in a 2D planar arrangement with the glass wool fibres showing a higher degree of planarity than the stone wool fibres. The orientation information is included in an analytical model based on a Euler–Bernoulli beam approximation. The model enables prediction of the transverse stiffness. It is indicated that the glass wool transverse stiffness is lower than the stone wool transverse stiffness. Comparison with experimental results confirms the assumption that the underlying deformation mechanism of mineral wool is the bending of fibre segments between bonds.     

Just Noticeable Differences and Weber Fraction of Oral Thickness Perception of Model Beverages

Rheological properties of beverages contribute considerably to texture perception. When developing new beverages, it is important to have knowledge on the smallest differences of viscosity which a consumer can discriminate. Thickness is the sensory attribute most commonly used to describe the viscosity of beverages. The aim of this study was to determine the Just Noticeable Differences (JNDs) of oral thickness perception and the Weber fraction (K) of Newtonian model stimuli (maltodextrin solutions). JNDs were determined using the method of constant stimuli with 5 reference stimuli ranging in viscosity from 10 to 100 mPa?s. JNDs increased with increasing viscosity of the reference stimulus. The Weber fraction (K) for oral thickness perception of model beverages was K = 0.26 for the studied viscosity range. The Weber fraction for oral thickness perception is comparable to Weber fractions reported in literature for perception of kinesthetic food firmness and spreadability, creaminess, sourness, and bitterness perception. This demonstrates that the human sensitivity towards oral discrimination of thickness of liquid stimuli is comparable to the human sensitivity towards discrimination of specific texture properties and specific taste stimuli.     

Self-Configuring Wireless Systems: Derivation of Re-Use Criteria and Neighbor-Lists

We address in this paper the autonomous derivation of re-use criteria, needed for channel assignment in channelized wireless voice and data communications systems, and of neighbor lists, needed for call-processing functions. We present an approach that relies on signal strength measurements collected by the system itself, during operation. This approach can be implemented with conventional equipment and functionality provided by the current air interface standards for circuit-based and packet-based access, employing either centralized or distributed control. No regularity requirements are imposed on the grid of cells or on the RF re-use pattern, and no knowledge is assumed of the base station locations. We describe the data collection mechanism and design the associated statistical hypothesis tests.     

Impacts des aménagements en montagne sur les processus hydrologiques et l’évolution géodynamique des versants (Les Arcs,Savoie, France)

This work focuses on the interaction between human activity in mountainous areas and slope movement hazards. The paper considers the triggering factors and processes of instability in the urbanized area of Les Arcs, an area exploited for mass ski runs and where many debris flows have occurred over the last 40 years. A progressive survey of the geological, geomorphological, hydrological, hydrogeological and climatic contexts is necessary to tackle the complexity of the phenomena. The human impact is considered as well. From the analysis, the geology associated with a specific climate was determined to be the main triggering factor for debris flow hazards. The influence of the glacial and postglacial period on the geomorphological aspects (e.g. steep slopes) and on the mechanical component of the superficial formations is the main factor. Furthermore, an analysis of regional meteorological data over the last 5 decades has emphasized a significant evolution of the climate since the 1960s which resulted in a general increase in temperature, rainfall (with seasonal variations) and the occurrence of extreme weather events, with long term implications for erosion and on water balance. This seems to be exacerbated by recent human activities which have significantly changed the natural environment: deforestation, changes in vegetation, the development of impervious surfaces such as roofs, roads and car parks, the creation of ski runs and the intensive exploitation of the catchment, all of which may have an influence on runoff and erosion affecting the natural surface structure. These changes and their effects on such factors as runoff and erosion have been reviewed and analyzed. In particular, the effects on hydrology have been highlighted by a hydrological modeling created using PCRaster Environmental Software. The hydrology of the Ravoire torrent before the creation of the ski resort was compared with the present configuration of the catchment. The annual water balance model shows that the ski resort generates a significant increase in the river flow compared to that before the change in land use. The parametric analyses undertaken revealed that the deforestation, the development of ski slopes and impervious areas are responsible for the reduction in infiltration inducing runoff. The maximum increase in water flow occurs during periods of natural high water flow (during snow melt) when the risk of debris flows is naturally high. For the last 20 years, this phenomenon has been amplified by the increasing production of artificial snow on the ski runs. Finally, a complementary model was created to consider the effects over a short time scale. The results of this rain event model emphasize the change in the hydrological response of the rivers after rainfall as a consequence of the change in land use. In particular this indicated a rise in the peak flow towards the resort, which may activate erosive processes above the debris flow source areas.      

Analysis of permeability of food plastic monolayers to methylethylketone (2-butanone) with the aromatran®

It is very important that measurements of the diffusion of aromas and volatile substances in trace amounts (p.p.m.) through synthetic materials, such as PVC, PE and PP monolayers, be accurate and repeatable. The primary goal of this work was to familiarize ourselves with the Aromatran®, a new, fully automated analytical instrument, for the measurement of a ketone (2-butanone or MEK) at 23°C. A discussion of results is provided, along with comments on the system's userfriendliness and the cost of the tests.