An experimental investigation of the influence of intermittent and continuous operating modes on the thermal behaviour of a full scale geothermal energy pile

Heat pumps connected to geothermal energy piles have variable operating hours. These variable hours can affect the thermal behaviour of these piles. Some key findings are presented for intermittent (16 hour) and continuous (24 hour) cooling modes in this abstract. It is found that the 16 hour cooling mode is more beneficial in terms of energy extraction, ground recovery, pile temperature and strain recovery

Friction compensation of an actively restrained clutch for path tracking

Friction compensation of an electromechanical friction clutch mechanism capable of restraining motion so that various predefined paths can be followed is investigated in this paper. The clutch mechanism is driven by an external source of energy, and a computer-controlled system is used to produce frictional resistance so that a desired motion can be achieved. Unknown stick-slip within the clutch is a critical characteristic of the system, which has to be overcome. Three different controllers are investigated in order to avoid stick-slip at low motion rates. A proportional-derivative controller, a sliding-mode controller, and a computed-torque controller, have been implemented and their performances compared using simulation and experimental analyses. The results demonstrate the effectiveness of the sliding-mode controller and the potential of a computed-torque controller for the motion control in a system with dry friction at low velocities

L'impact de l'homme sur la forêt dans la région de Tlemcen (Oranie-Algérie)

Les formations végétales actuellement en lambeaux et qui étaient bien représentées, il y a moins d'un siècle, subissent de nombreux dommages de la part de l'homme et de ses troupeaux. Leur stabilité est menacée à court terme dans toute la zone étudiée. En effet, le développement agricole et l'urbanisation dans la région imposent souvent l'augmentation des cheptels ovin, caprin et bovin dont l'élevage extensif provoque des dégâts considérable au milieu naturel. Ce travail comprend deux parties distinctes : - une analyse floristique montrant la transformation des structures forestières en matorrals clairsemés, - une description de la pression anthropozoogène sur les lieux fragilisés par les contraintes climatiques, accentuant la dégradation des groupes sylvatiques au profit des thérophytes à pouvoir envahissant

Bilan de la flore de la région de Tlemcen (Oranie-Algérie)

Dans l'ouest algérien, le sort des formations végétales n'a pas échappé à l'action dévastatrice de l'homme. Les écosystèmes forestiers et préforestiers voire steppiques de la région de Tlemcen ont subi d'énormes modifications, dues principalement à l'impact conjugué de l'homme et du climat

MCDHF calculations of isotope shifts in neutral antimony

Ab initio multiconfiguration Dirac–Hartree–Fock (MCDHF) calculations have been carried out in order to determine the isotope shift (IS) electronic parameters of transitions belonging to electric dipole (E1) transition arrays 5s25p3−5s25p26s, 5s25p26s−5s25p26p and 5s25p26s−5s25p27p in neutral antimony, Sb I. In a correlation model limited to single and double excitations from the valence shells, these parameters, combined with the changes in mean-square nuclear charge radius δ⟨r2⟩123,121 compiled by Angeli and Marinova [3] produce isotope shifts values in good agreement with the most recent measurements by high-resolution emission and optogalvanic absorption spectroscopy of Sobolewski et al. [5] but not with the old measurements of Buchholz et al. [4] for 5p3−5p26s. However, our analysis does not allow to reject the latter due to the large uncertainty affecting δ⟨r2⟩123,121, i.e. 0.072 ± 0.048 fm2 [3]. This shows the need of a more accurate determination of this nuclear parameter. Although improving excitation energies, the inclusion of core-valence correlation limited to one hole in the 4d core subshell destroyed the theory-experiment agreement on the IS parameters. © 2018 Elsevier LtdInteruniversity Attraction Poles Programm

RIM-BP2 primes synaptic vesicles via recruitment of Munc13-1 at hippocampal mossy fiber synapses

All synapses require fusion-competent vesicles and coordinated Ca(2+)-secretion coupling for neurotransmission, yet functional and anatomical properties show a high diversity across different synapse types. We show here that the presynaptic protein RIM-BP2 has diversified functions in neurotransmitter release at different central mammalian synapses and thus contributes to synaptic diversity. At hippocampal pyramidal CA3-CA1 synapses, RIM-BP2 loss has a mild effect on neurotransmitter release, by only regulating Ca(2+)-secretion coupling. However, at hippocampal mossy fiber synapses RIM-BP2 has a strong impact on neurotransmitter release by promoting vesicle docking/priming via recruitment of Munc13-1. In wild type mossy fiber synapses, the distance between RIM-BP2 clusters and Munc13-1 clusters is larger than in hippocampal pyramidal CA3-CA1 synapses, suggesting that spatial organization may dictate the role a protein plays in synaptic transmission and that differences in active zone architecture is a major determinant factor in the functional diversity of synapses

RIM-BP2 primes synaptic vesicles via recruitment of Munc13-1 at hippocampal mossy fiber synapses

All synapses require fusion-competent vesicles and coordinated Ca(2+)-secretion coupling for neurotransmission, yet functional and anatomical properties are diverse across different synapse types. We show that the presynaptic protein RIM-BP2 has diversified functions in neurotransmitter release at different central murine synapses and thus contributes to synaptic diversity. At hippocampal pyramidal CA3-CA1 synapses, RIM-BP2 loss has a mild effect on neurotransmitter release, by only regulating Ca(2+)-secretion coupling. However, at hippocampal mossy fiber synapses, RIM-BP2 has a substantial impact on neurotransmitter release by promoting vesicle docking/priming and vesicular release probability via stabilization of Munc13-1 at the active zone. We suggest that differences in the active zone organization may dictate the role a protein plays in synaptic transmission and that differences in active zone architecture is a major determinant factor in the functional diversity of synapses