This work is focused on the modelling of the shear and normal stresses in fibre suspensions that are subjected to a simple shear flow in the presence of short-range lubrication forces, van der Waals and electrostatic forces, as well as solid friction forces between fibres. All of these forces are weighed by the contact probability. The theory is developed for attractive fibres with van der Waals interaction dominating over electrostatic repulsion. The model predicts a simple Bingham law for both the shear stress and the first normal stress difference, with the apparent shear and normal yield stresses proportional to the second and the third power of the particle volume fraction respectively. The model is applied to the experimental data of Rakatekar et al. (Adv. Mater., vol. 21, 2009, pp. 874–878) and Natale et al. (AIChE J., vol. 60, 2014, pp. 1476–1487) on suspensions of carbon nanotubes dispersed in a Newtonian epoxy resin. It reproduces well the quadratic dependence of the apparent yield stress on the particle volume fraction $(\unicode[STIX]{x1D70E}_{Y}\propto \unicode[STIX]{x1D719}^{2})$ for average particle aspect ratios of $r=160$ and 1200, while it underpredicts the power-law exponent for $r=80$ (always predicting $\unicode[STIX]{x1D719}^{2}$ behaviour instead of $\unicode[STIX]{x1D719}^{3.2}$ ).

The photochemistry of CO and its isotoplogues affects the structure and evolution of many astronomical environments, including interstellar clouds, circumstellar disks around newly formed stars, and the envelopes surrounding highly evolved stars. When in the presence of a strong ultraviolet field, the primary destruction mechanism for interstellar and circumstellar CO is photodissociation, which is entirely governed by discrete line absorption into predissociating levels in the wavelength range 91.2 to 111.8 nm. Because the CO spectrum consists primarily of resolved line features, self-shielding effects in high-column density environments can lead to strong isotopic fractionation signatures in both CO and elemental oxygen and carbon; for example, CO self-shielding in the solar nebula has been invoked to explain the unusual oxygen isotope ratios observed in the earliest solar system condensates, viz. calcium-aluminum inclusions (CAIs) in primitive meteorites.

Cognitive reserve (CR) has been proposed as a latent variable that can account for the frequent discrepancy between an individual's underlying level of brain pathology and their observed clinical outcome. A possible behavioral manifestation of CR is best strategy choice. Older adults have been shown to choose sub-optimal strategies for performing various tasks. The present study attempted to investigate whether greater levels of CR could predict greater strategy selection, particularly in older adults. A computational estimation task was administered to 20 healthy young adults (mean age = 24.7 ± 3.6; 20–31 years) and 18 healthy older adults (68.2 ± 4.5; 62–77 years) wherein participants needed to estimate the product of two two-digit numbers by using one of two strategies. The results revealed an effect of age group on strategy choice and supported the hypothesis that CR is associated with increased strategy selection abilities. (JINS, 2013, 19, 1–4)

Interstellar water ice is mainly amorphous, but the nature of its morphology stillremains poorly known. The experimental study described in this work focuses on howrelevant changes of the ice morphology result from atomic hydrogen exposure and subsequentrecombination. We show that there is an exponential decrease in the porosity of theamorphous water ice sample following hydrogen-atom irradiation. These and other laboratoryresults lead us to suggest that water ice in space is almost certainly amorphous andnon-porous (compact).

We explore experimentally the formation of water molecules from O2 and D atomson bare grains composed of amorphous silicates analogous to those in diffuse interstellarclouds. We provide the fractions of D2O and D2O2molecules formed on the silicate surface held at 10 K from the O2 + D pathwayusing RAIRS and TPD techniques. For comparison, we also study the formation of watermolecules on surfaces covered with amorphous water ice representing the dense clouds.

We present a combined theoretical and experimental study of the adsorption of two pairsof organic isomers, (i) acetic acid AA (CH3COOH) and methylformate MF (HCOOCH3), and (ii) ethanol EtOH(CH3CH2OH) and dimethyl ether DME (CH3OCH3),onto crystalline water ice surfaces at low temperatures. Both approaches show that, foreach pair, the most stable isomer from a thermodynamical point of view,i.e. AA and EtOH, isalso the one which is the more tightly bound to the water ice surface compared to the lessstable isomers (MF and DME). This finding, which can be explained by the ability of AA orEtOH to efficiently interact with the ice surface via hydrogen bondings, may haveimportant consequences in an astrophysical context, since it could explain why the moststable isomer is not the most abundant observed in the interstellar gas phase.

For every mill the ideal roll can be considered as one that can be used in a mill stand indefinitely. Unfortunately for the roll user, such ideal rolls do not exist. One major reason for work roll changes (planned or unplanned) is “wear”. In the context of cold rolling and temper rolling, “wear” primarily refers to loss of roughness and/or surface texture. Another limitation to roll performance is the fact that mill incidents – minor as well as major incidents – inflict damage on the work rolls, requiring redressing in the roll shop. If a major defect is present in a forged roll, e.g. due to a mill incident, catastrophic roll failure may occur in a violent, explosive manner. Improvement of the value-in-use of a work roll implies a superior wear resistance, a superior damage resistance, and elimination of the safety risks associated with explosive roll failures. In order to deal with this in a concerted R&D approach, a consortium of two roll users in the steel industry, a leading roll manufacturer, a high-tech supplier of roll damage detection equipment, and specialised research institutes have joined forces. Cold rolling trials have been performed, using pilot mills as well as industrial mills, with both novel forged HSS work rolls and conventional forged 3–5%Cr steel work rolls. Separate trials have been designed to focus on either the aspect of roughness evolution or damage resistance. Complementary data from various laboratory tests and industrial mill and roll shop data have been collected. Models have been developed for damage evolution in a roll, and for roughness evolution of the roll surface. In addition, novel non-destructive detection systems and sensors have been designed and tested. This paper provides a concise overview of the results achieved.

In normal women sedation following intravenous administration of the α2-adrenoceptor agonist clonidine (1·3 μg/kg) was significantly greater following 3 weeks' continuous treatment with the combined contraceptive pill than at the end of the 7-day withdrawal period. In contrast, sedative responses to the dopamine agonist apomorphine (5 μg/kg subcutaneously) were decreased when subjects were taking the contraceptive pill. These findings are in agreement with animal experimental studies, indicating that oestrogen can alter α-adrenoceptor and dopamine autoreceptor sensitivity. Such interactions may be involved in the effects of female sex steroids on mood.

The motion of a plasmoid (plasma-field entity) across an inhomogeneous magnetic field distribution of which the direction and strength change along the penetration trajectory has been studied. The bulk velocity decreases when the plasma element penetrates into a region of increasing magnetic field. The critical magnetic field intensity where a plasmoid is stopped or deflected is found to be the same critical field as that which has been observed in laboratory experiments for a non-rotating B-field distribution. The polarization electric field induced inside a moving plasma element has been determined for both low-β and high-β plasmoids. The momentum density vector of a plasmoid is deflected in the – B × ∇B and – B × (B. ∇)B directions as it penetrates into an inhomogeneous B-field distribution. This kinetic model has been applied to the impulsive penetration of solar wind plasma irregularities impinging on the earth's geomagnetic field with an excess momentum density. As a consequence of impulsive penetration, a plasma boundary layer is formed where the intruding plasmoids are deflected eastward. Magnetospheric plasma is dragged in the direction parallel to the flanks of the average magnetopause surface. Diamagnetic effects of these impulsively penetrating plasmoids into the magnetosphere are also briefly discussed.

La mesure de la radioactivité atmosphérique constitue une difficulté métrologique majeure. En fonction des mécanismes de prélèvement sur filtre et des paramètres de mesure, l'activité alpha des aérosols est sous estimée. L’énergie cinétique des particules alpha est atténuée dans la matière qu’elles traversent, et une partie de cette énergie ne parvient plus au détecteur. Le rendement de mesure est alors dégradé et nécessite une correction. Pour répondre aux conditions de mesures usuelles, le laboratoire a développé un modèle empirique pour l'évaluation des corrections de l’activité alpha en fonction de la masse des aérosols déposés sur le filtre. Le modèle a été validé expérimentalement et a permis une meilleure estimation de l'incertitude sur la mesure de l'activité alpha des aérosols. L'étude a contribué à une première évaluation du facteur de correction pour des filtres peu encrassés provenant de la région parisienne : Fαlabo= 1,6 ± 0,5.

High power RF device performance decreases as operation temperature increases (e.g. decreasing electron mobility affects cut-off frequencies and degrades device reliability). Therefore determination of device temperature is a key issue for device topology optimisation. In this work the temperature variation of AlGaN/GaN high-electron-mobility transistors grown either on silicon or sapphire substrate under bias operation was measured by micro Raman scattering spectroscopy. Temperature measurements up to power dissipation of 16 W for 4 mm development devices were carried out and a peak temperature of 650 K was determined. The difference of thermal resistance for similar devices grown on the two different substrates was assessed. The thermal resistances of different device topologies were compared to optimise the component design.

The high power RF device performance decreases as the operation temperature increases (e.g. fall of electron mobility impacting the cut-off frequencies and degradation of device reliability). Therefore the determination of device temperature is a key issue for device topology optimisation. In this work the temperature variation of AlGaN/GaN high-electron-mobility transistors grown either on silicon or sapphire substrates under bias operation was measured by micro Raman scattering spectroscopy. The differences in thermal resistance for similar devices grown on the two different substrates were assessed. The thermal resistances of different device topologies were compared in order to optimise the component design. The temperature measurement across the gate and along the component fingers were made to quantify the thermal gradient of the device. Temperature measurement up to a power dissipation of 16 W for a 4 mm development device was carried out and the peak temperature of 650 K was determined.

The Faunal Reserve of the Lobéké area of south-eastern Cameroon is an important area for forest conservation. One day, it is hoped, it will be part of an international unit, in association with two protected areas in neighbouring countries (Dzanga-Ndoki National Park, Central African Republic and Nouabalé-Ndoki National Park, Congo). With a view to assessing the status of its avifauna in particular, 24 days were spent in three short surveys from 1997 to 1999. The main forest type is semi-evergreen, with an open canopy; the only natural savannas are small saline swamps. The total of 305 species of bird recorded includes a forest nightjar not yet identified (but more likely to be the rare Itombwe Nightjar Caprimulgus prigoginei than a new species) and the Dja River Warbler Bradypterus grandis. The latter is a species confined to Rhynchospora swamps and had not been re-located in Cameroon since it was first collected in 1914 west of the Dja river; the extent of suitable habitat in Lobéké makes this site the most important to date for its conservation. Other rare or little-known forest species recorded include Olive Ibis Bostrychia olivacea, Sandy Scops Owl Otus icterorhynchus, Zenker's Honeyguide Meligomon zenkeri, Tessmann's Flycatcher Muscicapa tessmanni and Yellow-capped Weaver Ploceus dorsomaculatus. Barred Owlet Glaucidium capense is locally common in open-canopy forest: this population was only recently discovered in central Africa and its taxonomic relationships have yet to be determined. We include a brief comparison with the avifauna of adjacent Dzangha-Ndoki National Park and Nouabalé-Ndoki National Park. A feature of the Lobéké avifauna is the presence of a few species normally associated with forest at higher altitudes (such as White-headed Wood Hoopoe Phoeniculus bollei, Uganda Woodland Warbler Phylloscopus budongoensis, Black-throated Apalis Apalis jacksoni), and perhaps absent from lower-lying Nouabalé-Ndoki.

This search deals with the control of a process in order to take into account non linearities without parameters identification. Neural networks properties are exploited for the modelling of non linear features, and a formalism is proposed to design a neural model which can be used directly as a controller. We apply this formalism to the modelling of a non linear mechanical load torque feature coupled to an induction machine in order to design a speed controller. A partial and a global neural method are presented. In order to overcome modelling errors or any process changes, an adaptive on line method is proposed. At last, simulation and experimental results are presented.

In this paper, finite element method is used to compute inductance parameters of asquirrel cage induction machine. To take into account saturation effect, saturatedequivalent parameters are introduced, which depend on the instantaneous value of themagnetising current. For a balanced induction machine, the particular inductance behaviors allow straightforward flux expressions without any cross saturation effect.Moreover, these expressions are explained thanks to an extended analytical approachconsidering a magnetic saliency phenomenon by a second order air-gap permeance. Asimple way of transformation ratio and leakage inductance computation is also deduced.The numerical results show the compatibility between finite element approach and extended analytical Park's method. Besides, two operating points (at no load and for nominal speed) studied by the both methods give very closed results.