Sub-hourly simulation of residential ground coupled heat pump systems

Residential Ground Coupled Heat Pump systems are usually characterised by an ON/OFF behaviour of the heat pump with typical cycling frequencies of 1 - 4 cycles per hour. The ground loop fluid pump has the same ON/OFF behaviour and the borehole heat exchanger operates either in full flow or no flow conditions. Typical hourly simulations of GCHP systems use steady-state models for the heat pump and the borehole fluid (transient models being used for buildings and heat transfer in the ground). This paper reviews the models used in typical hourly simulations as well as transient models that are available and compares the results obtained using the two classes of models within the TRNSYS simulation environment. Both the long-term energy performance and the optimum system design are compared. It is shown that using steady-state models leads to an overestimation of the energy use that ranges from a few percents with oversized borehole heat exchangers to 75% for undersized exchangers. A simple Life Cycle Cost analysis shows that using steady-state models can lead to selecting a very different design than the one that would have been selected using dynamic models

Le marché de l’assurance responsabilité des municipalités québécoises est-il contestable?

Cet article présente un test de la théorie des marchés contestables appliqué aux assurances responsabilité civile et professionnelle pour les petites municipalités québécoises. À la lumière des résultats de ce test, on ne peut rejeter l’hypothèse que le marché de l’assurance responsabilité civile est contestable pour la période considérée. On peut, par contre, rejeter cette hypothèse pour l’assurance responsabilité professionnelle.In this paper, the hypothesis that the liability insurance market for small municipalities in the province of Quebec functions "as if contestable" is tested. In light of our results, we cannot reject the hypothesis that the general liability market is indeed contestable. On the contrary, we reject this hypothesis in the case of the professional liability market

A Virtual Ground Station Based on Distributed Components for Satellite Communications

Communication with Low-Earth Orbit (LEO) satellites requires the set up of a ground station which is a complex and costly installation. Moreover, a LEO satellite is accessible only during certain time slots from a given ground station. In other words, access to LEO satellites is on an intermittent basis and is constrained by the availability of ground stations. The work presented in this paper aims at augmenting the accessibility to the services offered by LEO satellites. We have devised a concept of virtual ground station available over the Internet. A virtual ground station can be used by any client with a computer attached to the Internet which augments the degree of accessibility. Besides, a virtual ground station and its clients don\u27t have to be collocated. A client can access a satellite as long as a remote virtual ground station has access to it. As long as there are several virtual ground stations distributed at several locations, this architecture augments the degree of accessibility to satellites. The design of the virtual ground station is based on CORBA distributed components. The virtual ground station has been developed using an application framework we have created, hence reducing the amount of programming required to obtain it. Moreover, we have developed a client satellite tracking software that uses our virtual ground station. In this paper, we review the design and implementation of our virtual ground station concept. We also present the companion client satellite tracking software that we have developed

Le marché de l’assurance responsabilité des municipalités québécoises est-il contestable?

In this paper, the hypothesis that the liability insurance market for small municipalities in the province of Quebec functions "as if contestable" is tested. In light of our results, we cannot reject the hypothesis that the general liability market is indeed contestable. On the contrary, we reject this hypothesis in the case of the professional liability market. Cet article présente un test de la théorie des marchés contestables appliqué aux assurances responsabilité civile et professionnelle pour les petites municipalités québécoises. À la lumière des résultats de ce test, on ne peut rejeter l’hypothèse que le marché de l’assurance responsabilité civile est contestable pour la période considérée. On peut, par contre, rejeter cette hypothèse pour l’assurance responsabilité professionnelle.

Suivi spatio-temporel du couvert nival du Québec à l’aide des données NOAA-AVHRR

L’imagerie satellitaire dans le visible et l’infrarouge permet de cartographier le couvert nival à grande échelle, ce qui n’est pas facilement réalisable à partir des observations locales conventionnelles. Cependant, en raison de leur résolution spatiale inadéquate ou de la faible durée de leurs séries d’observations, les produits satellitaires actuellement disponibles sont inutilisables pour l’étude à long terme du couvert nival. Par conséquent, l’objectif de la présente étude a été de développer un algorithme opérationnel de cartographie de la neige à l’aide des données du capteur AVHRR (Advanced Very High Resolution Radiometer) embarqué à bord du satellite NOAA. Cette procédure doit permettre de suivre l’évolution spatio-temporelle de la neige au sol sur une longue période de temps et avec une bonne résolution spatiale. Les résultats de la cartographie ont été validés par rapport aux observations de l’occurrence et de l’épaisseur de la neige au sol. L’algorithme a été appliqué au territoire du Québec sur trois périodes spécifiques : 1998-1999, 1991-1992 et 1986-1987. L’algorithme a réussi à identifier la catégorie de surface (neige/non-neige) avec un taux de succès global moyen de 87 %. Les performances de l’algorithme ont été supérieures dans la détection de la neige (90 %) qu’elles l’ont été pour les surfaces sans neige (82 %). Également, l’algorithme a permis de situer le début des périodes de formation et de fonte de la neige, et ce tant au niveau local qu’à l’échelle du bassin versant.This work is part of a multidisciplinary study designed to validate the elements of the hydrological cycle of the Canadian regional climate model simulations (CRCM) over Quebec (Canada). These simulations, carried out over a 20-year period (1979-1999), aim at examining the annual and inter-annual hydrological budgets of a dozen catchments. Snow cover is a key factor in the modeling of the hydrological budget as well as the climatic changes. The remote sensing component of the project involves the use of satellite data in order to validate CRCM simulations of snow cover characteristics (i.e., snow cover extent), which are impossible to validate using conventional in situ snow observations.Satellite data in the visible and infrared spectra as well as passive microwaves represent an alternative source of information on snow cover. Various satellite snow products have been available since the middle of the 1960’s and a few are available in real time and online. However, their quality varies considerably with respect to sensor and platform characteristics, image processing procedures and snow classification techniques. Consequently, these operational products cannot be used for the validation of the CRCM simulations because of their limited spatial extent, or their coarse spatial resolution, or the lack of a continuous and homogeneous series of observations covering the targeted period (1979-1999). In addition, the coarse temporal resolution and the small areal coverage of high-resolution satellites limit their use for the temporal monitoring of snow cover on a regional scale. Consequently, it was decided to explore the potential of NOAA-AVHRR data for the space-time monitoring of snow on the ground and to produce snow cover maps. These maps would then be used to validate CRCM simulations. Among the 20 years concerned by the study (1979-1999), six winter seasons were targeted to be used in the validation process.The objective of this work was thus to develop a simple procedure of space-time monitoring of snow cover over the province of Quebec using AVHRR images. The algorithm was calibrated and validated over three winter seasons: 1998-1999, 1991-1992 and 1986-1987. In order to monitor snow cover, especially during snow setting and melt phases, the daily images from October 1st to December 15th and from April 1st to May 31st of each of the three periods were used. Images at the beginning of the afternoon were preferred since they are less sensitive to topographic effects and variation in illumination conditions. Only the images presenting a minimal cloud cover were retained (164 images out of the 411 initially identified). These selected images were used for the calibration and validation of the snow cover mapping algorithm. Selected AVHRR images were calibrated and corrected radiometrically and geometrically. A sub-region (82°30’ W, 58°N; 60° W, 46° N) covering the territory being studied was therefore extracted from each image.The classification algorithm used herein was developed from published classification techniques. This algorithm is based on sequential hierarchical thresholds in order to classify the AVHRR images into three surface categories: snow, no-snow and clouds. It consists of a combination of six sequential thresholds. The thresholds go from least restrictive to most severe. A pixel that successfully passes through all the thresholds is classified as snow; if the pixel does not pass through all the thresholds, it is categorized either as clouds or no-snow. The thresholds were established empirically and are consequently specific to Quebec conditions. The classification results were validated at the temporal and spatial levels using ground observations, specifically snow occurrence at Environment Canada’s meteorological stations.The algorithm was calibrated using pixel samples extracted from each selected image, above areas representing the three surface categories present within the scene. These areas were identified visually and delimited manually. Thereafter, radiometric data samples from all selected images were put together and their percentiles were calculated. The percentiles were used to build the values of the algorithm thresholds.For each of the three studied periods, two dates were chosen for the spatial validation of the snow maps produced using AVHRR images: one during the snow cover setting period (at the end of October) and the other for the snow melt period in spring (at the end of April). For these six dates, ground snow occurrence at meteorological stations was compared to the classification results. For temporal validation, snow occurrence observations at 15 meteorological stations during each of the three winter seasons were used for the classification algorithm. Corresponding ground observations were compared to the occurrence of snow class within 3 x 3-pixel windows centered on each station and the total accuracy statistics were therefore calculated. When 50% or more of the 3 x 3-pixel windows were classified as cloudy, the results for the corresponding station were excluded from the comparison.The classification results were quite accurate, with 87% of the pixels around validation meteorological stations being correctly identified. The algorithm successfully detected the presence of snow with a precision of 90% and 82% for no-snow surfaces. The algorithm performances in spring and autumn were similar. Also, the algorithm detected the presence of snow more accurately in open lands than in forested areas. We demonstrated that the algorithm allowed the location of the beginning of snow formation and melting periods at the local level as well as at the watershed scale, especially under clear sky conditions. The algorithm also captured interannual dynamics and spatial variations in the establishment and disappearance of snow cover. The use of high spatial resolution imagery (LANDSAT or SPOT) would improve the accuracy assessment of the algorithm results according to soil occupation types and pixel fractional snow coverage. The main limitation of the algorithm application is the presence of persistent clouds

A simple and efficient feedback control strategy for wastewater denitrification

Due to severe mathematical modeling and calibration difficulties open-loop feedforward control is mainly employed today for wastewater denitrification, which is a key ecological issue. In order to improve the resulting poor performances a new model-free control setting and its corresponding "intelligent" controller are introduced. The pitfall of regulating two output variables via a single input variable is overcome by introducing also an open-loop knowledge-based control deduced from the plant behavior. Several convincing computer simulations are presented and discussed.Comment: IFAC 2017 World Congress, Toulouse, Franc

A review of vertical ground heat exchanger sizing tools including an inter-model comparison

This paper attemps to fill a gap in the literature on ground heat exchanger sizing tools which are routinely used but have not been recently compared against each other. First, a comprehensive review of the governing equations of these tools is presented. The tools are then classified into five levels

Observation of the shock wave propagation induced by a high-power laser irradiation into an epoxy material

The propagation of laser-induced shock waves in a transparent epoxy sample is investigated by optical shadowgraphy. The shock waves are generated by a focused laser (3 ns pulse duration—1.2 to 3.4TWcm−2) producing pressure from 44 to 98.9 GPa. It is observed that the shock wave and the release wave created by the shock reverberation at the rear face are both followed by a dark zone in the pictures. This corresponds to the creation of a tensile zone resulting from the crossing on the loading axis of the release waves coming from the edge of the impact area (2D effects). After the laser shock experiment, the residual stresses in the targets are identified and quantified through a photoelasticimetry analysis of the recovered samples. This work results in a new set of original data which can be directly used to validate numerical models implemented to reproduce the behaviour of epoxy under extreme strain rate loading. The residual stresses observed prove that the high-pressure shocks can modify the pure epoxy properties, which could have an influence on the use made of these materials

L’intégration des services de santé mentale de première ligne. Étude du modèle développé à la Clinique communautaire de Pointe-St-Charles

L'examen d'une expérience de collaboration établie depuis 25 ans entre la Clinique communautaire de Pointe-St-Charles, qui a un mandat de Centre local de services communautaires, et l'hôpital Douglas, un centre spécialisé en psychiatrie, a permis de documenter un mode de partenariat particulier pour des services de santé mentale destinés à des adultes. Avec le soutien d'une équipe de consultants en psychiatrie disponible sur place, les professionnels 1 des équipes multidisciplinaires de première ligne sont responsables du plan de traitement établi et assurent un suivi de longue durée, si nécessaire. L'approche d'intervention mise également sur l'enracinement de cette Clinique dans le quartier et sur une tradition de collaboration avec plusieurs organismes communautaires qui accueillent les personnes suivies à cette clinique. Ce modèle d'organisation est soumis à des pressions, vu les transformations dans le réseau de la santé et des services sociaux. Cette étude, réalisée durant la période de reconfiguration des services de santé au Québec, a permis d'apporter un éclairage sur les conditions de réalisation du modèle d'intervention à la Clinique communautaire de Pointe-St-Charles et d'identifier des pistes d'amélioration, en considérant le point de vue des usagers et celui des professionnels impliqués.A close examination of the experience of collaboration established over the past 25 years between the Clinique communautaire de Pointe-St-Charles - which has the primary care mandate of a CLSC (local community services), and the Douglas Hospital, a centre specialized in psychiatry, - has allowed to document a particular type of partnership for adult mental health services. With the support of a team of psychiatric consultants, first line multidisciplinary teams of professionals are responsible for the treatment plan established as well as ensuring, if necessary, continuity of long-term care. This approach also counts on the fact this clinic is deeply-rooted in the neighborhood as well as on the tradition of collaboration with many community organizations servicing people treated at this clinic. This model of organization is submitted to pressures caused by the transformation of the health and social services system. This study realized during the transformation period, has allowed to shed new light on the conditions of realization of the intervention model at the Pointe-St-Charles community clinic and identify points of improvement by considering the perspective of consumers and professionals involved.El examen de una experiencia de colaboración establecido hace 25 anos entre la Clínica comunitaria de Pointe-St-Charles que tiene un mandato de Centro local de servicios comunitarios y el Hospital Douglas, un centro especializado en psiquiatría, ha permitido documentar un modo de trabajo conjunto, particular para los servicios de salud mental destinados a adultos. Con el apoyo de un equipo de consultantes en psiquiatría disponibles en el lugar, los profesionales de los equipos multidiciplinarios de primera línea son responsables del plan de tratamiento establecido y aseguran un seguimiento prolongado cuando es necesario. El modelo de intervención se basa igualmente en el enraizamiento de esta Clínica en el barrio y en la colaboración de varios organismos comunitarios que reciben a las personas que son seguidas en esta clínica. Dadas las transformaciones de la red de la salud y de los servicios sociales, este modelo organizacional está sometido a presiones. Este estudio, realizado durante le periodo de reconfiguración de los servicios de salud en el Quebec, ha permitido clarificar a cerca de las condiciones de realización del modelo de intervención en la Clínica comunitaria de Pointe-St-Charles e identificar las pistas para mejorarlo, considerando el punto de vista de los usuarios y de los profesionales implicados