Online unsupervised occupancy anticipation system applied to residential heat load management

Human preferences and lifestyles significantly impact buildings' energy consumption. Consequently, a better understanding of occupants' behavior is crucial to decrease energy consumption and maintain occupants' comfort. Occupant-centric control (OCC) strategies are effective approaches to fulfil such a purpose. As such, occupancy detection and prediction are of prime importance, particularly to manage Electric Space Heating (ESH) systems, due to the relatively slow dynamics of the temperature in dwellings. This paper proposes an Explicit Duration Hidden Markov Model (EDHMM) for unsupervised online presence detection and a hazard-based approach for occupancy prediction. Moreover, a control strategy using a cost function, weighted by occupancy predictions, and a load-shifting strategy based on time-varying electricity price are put forward. This work initially validates the consistency of the proposed approach by using synthetic data generated by a Monte Carlo simulation. Subsequently, the performance of our framework is compared with previous methods presented in the literature through experimental validation. Results demonstrate that the proposed EDHMM approach is efficient in detecting occupancy states. Besides, the results of the field implementation show the potential of the proposed control strategy to preserve occupants' thermal comfort while decreasing the heating energy consumption

Nouveau procédé de synthèse du nitrure d'aluminium

Thermodynamic considerations show that, even at room temperature, pure aluminium can react with nitrogen to form the aluminium nitride AlN. However, pure aluminium does not exist: it is always surrounded by an alumina shell that protects the metal from further reactions. Furthermore, in the hypothesis where one has been able to make aluminium react with nitrogen, an aluminium nitride shell will protect as well the metal core from further oxidation. Prompted by the Lanxide process allowing to form Al/Al$_2$O$_3$ composites, we have mixed aluminium powders with lithium salts, and easily synthesized pure aluminium nitride by heating the mixed powders in nitrogen at temperatures ranging from 800 to 1200 °C. Starting from aluminium powders with a specific area ranging from 0.3 to 4 m$^2$/g, we have been able to produce aluminium nitride with specific are ranging from 1 to 20 m$^2$/g. Mixed with Y203-CaO and sintered at 1720 °C in N$_2$, we obtained AIN ceramics owning 92% density and 160 W/m.K thermal conductivity.Les calculs thermodynamiques montrent que, même à température ambiante, l'aluminium pur peut réagir avec l'azote pour former le nitrure d'aluminium AlN. Cependant, la poudre d'aluminium pur n'existe pas : ses grains sont toujours entourés d'une couche d'alumine protectrice. De plus, dans l'hypothèse où l'on pourrait faire réagir de la poudre d'aluminium avec de l'azote, il se formerait de même une couche protectrice de nitrure d'aluminium qui empêcherait le centre des grains de réagir. S'inspirant du “procédé Lanxide” permettant de réaliser des composites Al/Al$_2$O$_3$, nous avons mélangé de la poudre d'aluminium avec des sels de lithium, et synthétisé du nitrure d'aluminium pur en portant ce mélange dans l'azote à une température pouvant être comprise entre 800 et 1 200 °C. Utilisant des poudres d'aluminium possédant une surface spécifique comprise entre 0,3 et 4 m$^2$/g, nous avons obtenu une poudre de nitrure d'aluminium avec une surface spécifique comprise entre 1 et 20 m$^2$/g. Mélangeant classiquement cette poudre avec Y$_2$O$_3$-CaO, nous avons obtenu après frittage à 1 720 °C dans N$_2$ des céramiques densifiées à 92 % et possédant une conductivité thermique de 160 W/m.K

Double external cavity laser diode for DWDM applications

International audienceA balanced dual-wavelength external cavity laser diode operating at 1.3 µm is reported with a side-mode suppression ratio of >35 dB. The construction of this laser is based on a double external cavity using a 1:2 coupler and two different Bragg reflectors photo-written within each channel. Thanks to the photo-written external cavity behaviour, a laser with more than eight channels could be considered

Double external cavity laser diode for DWDM applications

International audienceA balanced dual-wavelength external cavity laser diode operating at 1.3 µm is reported with a side-mode suppression ratio of >35 dB. The construction of this laser is based on a double external cavity using a 1:2 coupler and two different Bragg reflectors photo-written within each channel. Thanks to the photo-written external cavity behaviour, a laser with more than eight channels could be considered

PEROVSKITES OXYNITRUREES UTILISEES EN TANT QUE MATERIAUX DIELECTRIQUES

L'introduction d'azote dans le réseau anionique d'une pérovskite de type ABX3 permet l'obtention d'une nouvelle famille de matériaux. Il est nécessaire de compenser l'augmentation consécutive des charges par des substitutions dans le sous-réseau cationique. Les matériaux préparés jusqu'à maintenant possèdent une maille cubique et il existe un désordre statistique entre oxygène et azote. Ils possèdent des constantes diélectriques élevées et stables dans un grand domaine de température et de fréquence. Contrairement aux pérovskites classiquement utilisées dans les condensateurs multicouches céramiques qui doivent obligatoirement être frittées en atmosphère oxydante ce qui impose l'emploi d'électrodes internes constituées de métaux nobles, ceux-ci sont stables à haute température sous atmosphère neutre ou réductrice.Introduction of nitrogen into the anionic network of a ABX3 type perovskite leads to a new family of materials. The consequent increase of charges has to be compensated with cationic substitutions. The up to now obtained materials have a cubic cell and we noticed a statistical disorder between oxygen and nitrogen. they are characterized by high and stable dielectric constants in a large scale of temperature or frequency. Perovskites usually used in multilayer ceramic capacitors have to be sintered in an oxydizing atmosphere that leads to the use of noble inner electrode metals. On the contrary, the present materials are stable at high temperature under neutral or reducing atmosphere

Collective Microoptics on Fiber Ribbon for Optical Interconnecting Devices

International audienceNew microoptics are proposed to interconnect single-mode fiber (SMF) ribbons. These microoptics allow the increase of the fiber spot size. Low loss, wide misalignment tolerances, long working distance, and low cost could be achieved. The fabrication process and experimental results are presented

Highly efficient collective coupling between laser diode array and lensed fibre ribbon

International audienceA new concept is proposed for lensed fibres fabricated according to a collective and low cost process. This process is based on cleaving and splicing of optical fibre ribbons and is suitable for the coupling of laser diode arrays and fibre ribbons