Performance evaluation of an air-to-air heat pump coupled with temperate air-sources integrated into a dwelling

ISBN : 978-0-947649-40-1 Disponible à l'adresse : http://www.ibpsa.org/proceedings/BS2009/BS09_2266_2273.pdfInternational audienceAn inverter-driven air-to-air heat pump model has been developped and implemented in the thermal simulation tool COMFIE, in order to compare the seasonal performance of a variable capacity air-to-air heat pump coupled with temperate air sources (crawlspace, attic, sunspace, heat recovery ventilation, earth-to-air heat exchanger) with the performance of a conventionally installed heat pump. The empirical model of the heat pump is presented in this paper, including full-load and part-load model at rating and non rating conditions, and also frosting conditions. Several coupling configurations are studied and applied on a case study: a French typical residential house. The influence of the climatic region is evaluated, giving indications on energy saving using such systems

Simulation of the thermal interaction between a building integrated photovoltaic collector and an airsource heat pump

Disponible à l'adresse : http://leso.epfl.ch/files/content/sites/leso/files/download/publications/cisbat_proceedings_final_download.pdfInternational audienceThe number of buildings simultaneously equipped with air-source heat pumps and photovoltaic collectors is constantly increasing. Nevertheless, both systems are installed independently, and their thermal interaction is not taken into account. In addition to electricity, the photovoltaic collector produces heat which can be used to increase the temperature of the source of the heat pump, thus improving its COP (Coefficient Of Performance). Inversely, the fluid cooled by the external unit of the heat pump can be used to lower the operating temperature of the photovoltaic collector, improving its electrical efficiency. This paper presents the methodology employed to simulate this kind of system and gives some results. The two systems (heat pump and photovoltaic collector) have been modelled and implemented in a thermal simulation tool of buildings. The resulting software enables to take into account the thermal interaction between each physical object (heat pump, PV collector and building) in a dynamic way. Simulations are run for the whole year and with a time step of one hour. The aim of this development is to evaluate the increase of efficiency of the combined system installed in a building compared to the case where both systems are installed independently. The simulation tool is applied on a case study : a single family house with a living area of 135 m2 and recently renovated. The south oriented roof gives enough space to install a 30 m2 photovoltaic collector. The external unit of the heat pump is installed in the attic just beneath the PV collector, which preheats the incoming air. The results illustrate how the thermal interaction between both systems can be taken into account

Software assembly and open standards for driving simulation

International audienceDriving simulation systems involve a combination of different computation codes. Although some of these modules are application-specific, their majority is reusable and state-of-the-art implementations are readily available in the open source community. This study investigates whether these open source libraries can combine to build a driving simulation application with reasonable performance. To this end, a component-oriented architecture is proposed, in which modules encapsulate relevant libraries behind a standard interface and exchange simulation data through a message passing interface. By integrating a render engine, a physics library and a simple vehicle dynamics model, we were able to rapidly build a functional minimal simulation application supporting distributed execution over a cluster of computers. As this architecture allows the transparent modification of module code and simplifies the addition of new modules, this kernel represents the foundations of an extensible and reconfigurable open source system dedicated to driving simulation. Details on this kernel application and ongoing development of this platform can found at http://open-s.sourceforge.net.Les logiciels de simulation de conduite reposent sur une combinaison de différents codes de calculs. Bien qu’une partie de ces modules soit extrêmement dépendante d’un usage particulier, leur majorité est réutilisable et certaines implémentations de pointe sont disponibles dans la communauté du logiciel libre. Cette étude vise à déterminer s’il est possible de combiner ces bibliothèques libres afin de construire une application de simulation de conduite atteignant de raisonnables performances. A cette fin, nous proposons une architecture orientée composant, selon laquelle ces bibliothèques sont encapsulées dans des modules s’échangeant des données relatives à la simulation au travers d’une interface d’échange de messages. En intégrant à cette architecture un moteur graphique, une bibliothèque de simulation de physique et un simple modèle de dynamique de véhicule, nous avons pu rapidement mettre en place une application de simulation minimale, pouvant s’exécuter de manière distribuée sur un cluster d’ordinateurs. Cette architecture permettant de modifier le code d’un module de manière transparente et simplifiant l’ajout de nouveaux modules, ce noyau constitue la base d’un logiciel libre extensible et polymorphique dédié à la simulation de conduite dont les détails peuvent être consultés sur le site : http://open-s.sourceforge.net

Software assembly and open standards for driving simulation

Driving simulation systems involve a combination of different computation codes. Although some of these modules are application-specific, their majority is reusable and state-of-the-art implementations are readily available in the open source community. This study investigates whether these open source libraries can combine to build a driving simulation application with reasonable performance. To this end, a component-oriented architecture is proposed, in which modules encapsulate relevant libraries behind a standard interface and exchange simulation data through a message passing interface. By integrating a render engine, a physics library and a simple vehicle dynamics model, we were able to rapidly build a functional minimal simulation application supporting distributed execution over a cluster of computers. As this architecture allows the transparent modification of module code and simplifies the addition of new modules, this kernel represents the foundations of an extensible and reconfigurable open source system dedicated to driving simulation. Details on this kernel application and ongoing development of this platform can found at http://open-s.sourceforge.net.Les logiciels de simulation de conduite reposent sur une combinaison de différents codes de calculs. Bien qu’une partie de ces modules soit extrêmement dépendante d’un usage particulier, leur majorité est réutilisable et certaines implémentations de pointe sont disponibles dans la communauté du logiciel libre. Cette étude vise à déterminer s’il est possible de combiner ces bibliothèques libres afin de construire une application de simulation de conduite atteignant de raisonnables performances. A cette fin, nous proposons une architecture orientée composant, selon laquelle ces bibliothèques sont encapsulées dans des modules s’échangeant des données relatives à la simulation au travers d’une interface d’échange de messages. En intégrant à cette architecture un moteur graphique, une bibliothèque de simulation de physique et un simple modèle de dynamique de véhicule, nous avons pu rapidement mettre en place une application de simulation minimale, pouvant s’exécuter de manière distribuée sur un cluster d’ordinateurs. Cette architecture permettant de modifier le code d’un module de manière transparente et simplifiant l’ajout de nouveaux modules, ce noyau constitue la base d’un logiciel libre extensible et polymorphique dédié à la simulation de conduite dont les détails peuvent être consultés sur le site : http://open-s.sourceforge.net

The use of whole‑body cryotherapy: time‑ and dose‑response investigation on circulating blood catecholamines and heart rate variability

Purpose A predominance of parasympathetic drive is observed following cold exposure. Such modulation of the autonomic nervous system (ANS) is associated with faster post-exercise recovery. Within this context, whole-body cryotherapy (WBC) has been spreading in sport medicine, though the optimal temperature and frequency are unclear. The aim of this study was to examine the effects of different cryotherapy conditions on the sympathovagal balance. Methods Forty healthy males were randomly assigned into five different groups (− 110 °C, − 60 °C, − 10 °C, control temperature [≃ 24 °C]) and undertook 5 WBC sessions over 5 consecutive days. Cardiac autonomic activity was assessed through heart rate variability (HRV) using power density of high frequency (HF), root-mean square difference of successive R–R intervals (RMSSD) and sympathovagal balance (LF/HF). Systemic sympathetic activity was assessed via circulating blood catecholamines. Results Mean weekly RMSSD (pre: 48 ± 22 ms, post: 68 ± 29 ms) and HF (pre: 607 ± 692 ms2, post: 1271 ± 1180 ms2) increased (p < 0.05) from pre to post WBC, only in the − 110 °C condition. A rise in plasma norepinephrine was found after the first − 110 °C WBC session only (pre: 173 ± 98, post: 352 ± 231 ng L−1, p < 0.01); whereas, it was not significant after the 5th session (pre: 161 ± 120, post: 293 ± 245 ng L−1, p = 0.15). Conclusion These results suggest that one − 110 °C WBC exposure is required to stimulate the ANS. After five daily exposures, a lower autonomic response was recorded compared to day one, therefore suggesting the development of physiological habituation to WBC

Sensitivity analysis of optimal transient growth for turbulent boundary layers

Structural approaches based on modal decomposition of the flow dynamics have gained acceptance for a wide variety of turbulent shear flows. In this context, a singular value decomposition associated with a governing operator, aiming to model the linear amplification of coherent structures, is used to reproduce some fundamental motions in a turbulent boundary layer. In particular, as already found by Cossu et al. (2009), elongated streaky structures scaled in inner and outer units are identified. The sensitivity of these singular values to a mean flow modification is analysed. It is illustrated that the linear amplification of very large-scales which populate the outer motion is not affected when the leading singular value associated with the inner layer is damped. Moreover, we notice that the resulting optimal mean flow deviation is consistent with findings of Xu et al. (2007) in which the active control of a turbulent boundary layer is studied through direct numerical simulations

Effects of Whole-Body Cryotherapy vs. Far-Infrared vs. Passive Modalities on Recovery from Exercise-Induced Muscle Damage in Highly-Trained Runners

Enhanced recovery following physical activity and exercise-induced muscle damage (EIMD) has become a priority for athletes. Consequently, a number of post-exercise recovery strategies are used, often without scientific evidence of their benefits. Within this framework, the purpose of this study was to test the efficacy of whole body cryotherapy (WBC), far infrared (FIR) or passive (PAS) modalities in hastening muscular recovery within the 48 hours after a simulated trail running race. In 3 non-adjoining weeks, 9 well-trained runners performed 3 repetitions of a simulated trail run on a motorized treadmill, designed to induce muscle damage. Immediately (post), post 24 h, and post 48 h after exercise, all participants tested three different recovery modalities (WBC, FIR, PAS) in a random order over the three separate weeks. Markers of muscle damage (maximal isometric muscle strength, plasma creatine kinase [CK] activity and perceived sensations [i.e. pain, tiredness, well-being]) were recorded before, immediately after (post), post 1 h, post 24 h, and post 48 h after exercise. In all testing sessions, the simulated 48 min trail run induced a similar, significant amount of muscle damage. Maximal muscle strength and perceived sensations were recovered after the first WBC session (post 1 h), while recovery took 24 h with FIR, and was not attained through the PAS recovery modality. No differences in plasma CK activity were recorded between conditions. Three WBC sessions performed within the 48 hours after a damaging running exercise accelerate recovery from EIMD to a greater extent than FIR or PAS modalities

Iterative destriping and photometric calibration for Planck-HFI, polarized, multi-detector map-making

We present an iterative scheme designed to recover calibrated I, Q, and U maps from Planck-HFI data using the orbital dipole due to the satellite motion with respect to the Solar System frame. It combines a map reconstruction, based on a destriping technique, juxtaposed with an absolute calibration algorithm. We evaluate systematic and statistical uncertainties incurred during both these steps with the help of realistic, Planck-like simulations containing CMB, foreground components and instrumental noise, and assess the accuracy of the sky map reconstruction by considering the maps of the residuals and their spectra. In particular, we discuss destriping residuals for polarization sensitive detectors similar to those of Planck-HFI under different noise hypotheses and show that these residuals are negligible (for intensity maps) or smaller than the white noise level (for Q and U Stokes maps), for l > 50. We also demonstrate that the combined level of residuals of this scheme remains comparable to those of the destriping-only case except at very low l where residuals from the calibration appear. For all the considered noise hypotheses, the relative calibration precision is on the order of a few 10e-4, with a systematic bias of the same order of magnitude.Comment: 18 pages, 21 figures. Match published versio

Influencia de la oposición en la velocidad de lanzamiento en jugadores de balonmano de élite, amateur y formación

El éxito del lanzamiento a portería en balonmano depende en gran medida de la velocidad del balón. Existen escasas evidencias sobre cómo afecta la toma de decisión y oposición en la velocidad del lanzamiento, sin embargo estas hacen presagiar cierta influencia. El presente estudio pretende analizar las diferencias en la velocidad de lanzamiento sin y con oposición. Para ello, ciento seis jugadores de élite internacional (E), amateur (A) y edades formativas (F) fueron evaluados en dos situaciones de velocidad de lanzamiento: sin oposición (VSO) y con oposición (VCO). El análisis de diferencias entre medias constató que la VCO fue inferior (5%; p menor que 0,01) a la VSO mientras que el análisis de la relación reveló valores de correlación medios entre la VSO y la VCO en E (r=0,597; p menor que 0,05) y A (r=0,598; p menor que 0,01) y bajos en F (r=0,378, p=0,01) Se confirma una influencia de la oposición y toma de decisión en la velocidad de lanzamiento, haciendo disminuir la misma. Existe una relación entre la velocidad de lanzamiento sin y con oposición positiva y significativa en los tres grupos analizados