Maintenance of Positive Diversity-Stability Relations along a Gradient of Environmental Stress

Environmental stress is widely considered to be an important factor in regulating whether changes in diversity will affect the functioning and stability of ecological communities.We investigated the effects of a major environmental stressor (a decrease in water volume) on diversity-abundance and diversity-stability relations in laboratory microcosms composed of temperate multi-trophic rock pool communities to identify differences in community and functional group responses to increasing functional group richness along a gradient of environmental stress (low, medium, and high water volume). When a greater number of functional groups were present, communities were less temporally variable and achieved higher abundances. The stabilizing effect of increased functional group richness was observed regardless of the level of environmental stress the community was subjected too. Despite the strong consistent stabilizing effect of increased functional group richness on abundance, the way that individual functional groups were affected by functional group richness differed along the stress gradient. Under low stress, communities with more functional groups present were more productive and showed evidence of strong facilitative interactions. As stress increased, the positive effect of functional group richness on community abundance was no longer observed and compensatory responses became more common. Responses of individual functional groups to functional group richness became increasing heterogeneous are stress increased, prompting shifts from linear diversity-variability/abundance relations under low stress to a mix of linear and non-linear responses under medium and high stress. The strength of relations between functional group richness and both the abundances and temporal variability of functional groups also increased as stress increased.While stress did not affect the relation between functional group richness and stability per se, the way in which functional groups responded to changes in functional group richness differed as stress increased. These differences, which include increases in the heterogeneity of responses of individual functional groups, increases in compensatory dynamics, and increases in the strength of richness-abundance and richness-variability relations, may be critical to maintaining stability under increasingly stressful environmental conditions

Environmentally conscious production through better nozzle design

This paper describes a the improvement of process where a lubrication system had been designed in an era when environmental regulations were more lax and did not require sophisticated methods of feeding lubricant to the work, in short when \u201ctin can\u201d lubrication methods were adequate. The particular process is pilger rolling and before the improvements were made the process was considered an environmental hazard, by the department of labour, when in production. By redesigning the lubricant nozzles with information gleaned from numerical model studies of laminar jet flow from different shaped orifices it was possible to redesign the nozzles so that the environmental safety hazard was completely reduced. An added benefit was the reduction in the amount of lubricant needed, from 300 litres per minute to 30 litres per minute. This reduced the oil and power requirements. The product quality was also equaled or increased and downtime was decreased, thereby increasing productivity.Peer reviewed: YesNRC publication: Ye

HUDAC MARK XI Research Project : Performance of Solar Heating System, 1979-1980

The Division of Building Research and the Housing and Urban Development Association of Canada (HUDAC) have been cooperating on a project to study energy use in four detached houses located near Ottawa. One of the objectives of the project was to evaluate the performance of the air- based solar heating system installed on House 3 and to compare its energy saving potential with that of other energy saving measures. The solar system was monitored in some detail through the 1979-80 heating season. This note describes the operational experience with the solar system and presents an evaluation of its performance, including the net energy savings and the effect of the system on building performance.La Division des recherches en b\ue2timent et l'Association canadienne de l'habitation et du d\ue9veloppement urbain ( ACHDU) collaborent \ue0 une \ue9tude sur la consommation \ue9nerg\ue9tique de quatre maisons individuelles construites pr\ue8s d'Ottawa. Un des objectifs de cette \ue9tude consistait \ue0 \ue9valuer la performance de l'installation de chauffage solaire \ue0 air de la maison 3 et \ue0 comparer le potentiel d'\ue9conomie d'\ue9nergie avec celui d'autres mesures d'\ue9conomie d'\ue9nergie. L'installation a \ue9t\ue9 contr\uf4l\ue9e tout au long de la saison de chauffe 1979-1980. Cette Note d\ue9crit l'exp\ue9rience et \ue9value la performance de l'installation solaire, pr\ue9sente les \ue9conomies d'\ue9nergie nettes r\ue9alis\ue9es et examine les effets de l'installation sur la performance du b\ue2timent.Peer reviewed: NoNRC publication: Ye

NRC 14-House Solar Demonstration Program : First-Year Performance Data

During 1976/77 the NRC funded the design and installation of 14 active solar space-heating systems in single-family homes as part of its solar demonstration program. Both air- and liquid-based systems were installed in new and existing dwellings. A description of the houses and systems is provided in this Note as well as a limited performance summary of six of the houses. Problems associated with design, construction and operation of the project houses are also discussed.En 1976-1977, le CNRC a financ\ue9 la conception et l'installation de 14 syst\ue8mes actifs de chauffage solaire pour des maisons unifamiliales, dans le cadre de son programme de d\ue9monstration solaire. On a install\ue9 des syst\ue8mes \ue0 air et \ue0 liquide dans des habitations neuves ou existantes. L'article contient une description des maisons et des syst\ue8mes ainsi qu'un r\ue9sum\ue9 restreint sur les performances de 6 de ces maisons. On expose aussi les probl\ue8mes associ\ue9s \ue0 la conception, \ue0 la construction et \ue0 l'exploitation des maisons du projet.Peer reviewed: NoNRC publication: Ye

Flow Field in the Vicinity of a High-Pressure-Drop Ball Valve.

NRC publication: Ye

Eurodyn Combustor Test and Evaluation

NRC publication: Ye

NRC Solar monitoring program

Peer reviewed: YesNRC publication: Ye

An Experimental Investigation of Vortex-Shedding Characteristics in a Cascade of Transonic Turbine Vanes.

Peer reviewed: YesNRC publication: Ye

NRC Solar Monitoring Program

Monitoring systems have been installed by NRC in several solar heated buildings to obtain data on the thermal and mechanical performance of the heating system used. Methods of monitoring a variety of solar system designs and applications are described and problems encountered in the studies are discussed.Des syst\ue8mes de monitorage ont \ue9t\ue9 install\ue9s par le CNRC dans plusieurs b\ue2timents chauff\ue9s \ue0 l'\ue9nergie solaire, de facon \ue0 obtenir des donn\ue9es sur les performances thermiques et m\ue9caniques des syst\ue8mes de chauffage utilis\ue9s. L'ouvrage expose les m\ue9thodes de monitorage des diff\ue9rents syst\ue8mes et applications et d\ue9crit les probl\ue8mes rencontr\ue9s.Peer reviewed: NoNRC publication: Ye