Development of a simulation-based decision support tool for renewable energy integration and demand-supply matching

This paper describes a simulation-based decision support tool, MERIT, which has been developed to assist in the assessment of renewable energy systems by focusing on the degree of match achievable between energy demand and supply. Models are described for the prediction of the performance of PV, wind and battery technologies. These models are based on manufacturers' specifications, location-related parameters and hourly weather data. The means of appraising the quality of match is outlined and examples are given of the application of the tool at the individual building and community levels

Development and demonstration of a renewable energy based demand/supply decision support tool for the building design profession

Future cities are likely to be characterised by a greater level of renewable energy systems deployment. Maximum impact will be achieved when such systems are used to offset local energy demands in contrast to current philosophy dictating the grid connection of large schemes. This paper reports on the development of a software tool, MERIT, for demand/ supply matching. The purpose of MERIT is to assist with the deployment of renewable energy systems at all scales. This paper describes the procedures used to match heterogeneous supply technologies to a set of demand profiles corresponding to the different possible fuel types

On the fidelity of the core mass functions derived from dust column density data

Aims: We examine the recoverability and completeness limits of the dense core mass functions (CMFs) derived for a molecular cloud using extinction data and a core identification scheme based on two-dimensional thresholding. Methods: We performed simulations where a population of artificial cores was embedded into the variable background extinction field of the Pipe nebula. We extracted the cores from the simulated extinction maps, constructed the CMFs, and compared them to the input CMFs. The simulations were repeated using a variety of extraction parameters and several core populations with differing input mass functions and differing degrees of crowding. Results: The fidelity of the observed CMF depends on the parameters selected for the core extraction algorithm for our background. More importantly, it depends on how crowded the core population is. We find that the observed CMF recovers the true CMF reliably when the mean separation of cores is larger than their mean diameter (f>1). If this condition holds, the derived CMF is accurate and complete above M > 0.8-1.5 Msun, depending on the parameters used for the core extraction. In the simulations, the best fidelity was achieved with the detection threshold of 1 or 2 times the rms-noise of the extinction data, and with the contour level spacings of 3 times the rms-noise. Choosing larger threshold and wider level spacings increases the limiting mass. The simulations show that when f>1.5, the masses of individual cores are recovered with a typical uncertainty of 25-30 %. When f=1 the uncertainty is ~60 %. In very crowded cases where f<1 the core identification algorithm is unable to recover the masses of the cores adequately. For the cores of the Pipe nebula f~2.0 and therefore the use of the method in that region is justified.Comment: 9 pages, 6 figures, accepted for publication in A&

Enhancing Small Group Teaching in Plant Sciences: A Research and Development Project in Higher Education

The Department of Plant Sciences at the University of Cambridge uses a range of learning and teaching environments including lectures, practical laboratories and small group tutorials'. Under the auspices of the Cambridge-MIT Institute's Pedagogy Programme, a two-year research and development project concerned with the development of small-group teaching is being undertaken. The research element of this project endeavours to illuminate current practice and identify areas in which evidence-based development might take place. The development element will include professional development activities and the production of curriculum resources including appropriate online material. This is a multi-method study including a series of student questionnaires; focus groups of students; semi-structured interviews with staff members; and the collection of video of small group teaching. In this paper we report selected findings from the 'student data' of the first year of this project.The questionnaire, conducted with two cohorts of students (2nd and 3rd year Undergraduates), used a double-scale questionnaire in which students were asked to report both on the prevalence of a range of teaching and learning practices and on how valuable these were in supporting their learning. This type of questionnaire instrument is particularly appropriate because the data it generates is suggestive of areas for changes in practice. The gaps between 'practices' and 'values' (across both cohorts) suggested that students valued activities which improved their understanding of how elements of the course were interrelated; which related course content to 'authentic' examples; and those in which teachers made explicit the characteristics of 'high quality' student work. Small group teaching, in the view of most students, was best used to extend and explore concepts introduced in lectures rather than simply reinforcing them or assessing student understanding.Data gathered through focus group activities illuminated the questionnaire data, providing detailed accounts of how students managed their own learning, and the roles played in this by lectures, small group teaching and other resources. Students identified the processes of planning and writing essays as key learning activities during which they integrated diverse course content and reflected on problematic knowledge. Questionnaire and focus group data suggested that students had less clear views regarding the value of collaborative learning, peer-assessment or activities such as making presentations to other students. When students talked in positive terms about these activities, they often referred to the learning benefits of preparation for the tasks rather than of the collaborative activities themselves. These views may provide indications of potential barriers to changes in learning and teaching environments, and suggest that any such changes may have to be carefully justified to students in terms of benefits to their own learning. Many of our findings are broadly in accord with other work on teaching and learning in Higher Education settings (such as the 'Oxford Learning Context Project' and the 'Enhancing Teaching-Learning Environments in Undergraduate Courses' Project) in that 'deep learning' and 'authenticity' in learning activities are valued by students, and that the introduction of specific formative practices (such as sharing notions of 'quality') would be welcomed. At the same time, amongst the students in our sample, a view of learning as an individual process of 'learning-as-acquisition' predominates over a view that it is a social process of 'learning-as-participation', and this will inform the planning of the 'development' aspect of the project. We conclude with a discussion of how the approach we have used might be more widely applied both within and beyond the Cambridge-MIT partnership. We also identify potential affordances of, and barriers to, the development of research-informed teaching in Higher Education

A Physical Limit to the Magnetic Fields of T Tauri Stars

Recent estimates of magnetic field strengths in T Tauri stars yield values $B=1$--$4\,{\rm kG}$. In this paper, I present an upper limit to the photospheric values of $B$ by computing the equipartition values for different surface gravities and effective temperatures. The values of $B$ derived from the observations exceed this limit, and I examine the possible causes for this discrepancy

Merit - An evaluation tool for 100% renewable energy provision

Islands represent an interesting challenge in terms of energy supply. A great deal of work has been carried out to look at specific aspects of this issue on different islands. Unfortunately, results from one study cannot be easily applied to other islands due to island-specific resources and energy-use profiles. A quantitative evaluation tool (MERIT) is presented here, which is able to match half-hourly energy demands (heat, electricity, hot water and transport) with local supplies. The program examines the energy balance on any scale, from an individual building through to an entire country, thereby providing a powerful and generic aid to decision making. This paper demonstrates the generality and usefulness of MERIT by using it to analyse the options for creating an energy-autonomous community on a typical, small island off the west coast of Scotland. Results are presented showing the feasibility of accomplishing 100% renewable provision on this island using available local resources

The effect of a strong external radiation field on protostellar envelopes in Orion

We discuss the effects of an enhanced interstellar radiation field (ISRF) on the observables of protostellar cores in the Orion cloud region. Dust radiative transfer is used to constrain the envelope physical structure by reproducing SCUBA 850 micron emission. Previously reported 13CO, C17O and H2CO line observations are reproduced through detailed Monte Carlo line radiative transfer models. It is found that the 13CO line emission is marginally optically thick and sensitive to the physical conditions in the outer envelope. An increased temperature in this region is needed in order to reproduce the 13CO line strengths and it is suggested to be caused by a strong heating from the exterior, corresponding to an ISRF in Orion 10^3 times stronger than the "standard" ISRF. The typical temperatures in the outer envelope are higher than the desorption temperature for CO. The C17O emission is less sensitive to this increased temperature but rather traces the bulk envelope material. The data are only fit by a model where CO is depleted, except in the inner and outermost regions where the temperature increases above 30-40 K. The fact that the temperatures do not drop below approximately 25 K in any of the envelopes whereas a significant fraction of CO is frozen-out suggest that the interstellar radiation field has changed through the evolution of the cores. The H2CO lines are successfully reproduced in the model of an increased ISRF with constant abundances of 3-5x10^{-10}.Comment: 11 pages, 10 figures. Accepted for publication in A&

Environmental Conditions and Vegetation Recovery at Abandoned Drilling Mud Sumps in the Mackenzie Delta Region, Northwest Territories, Canada

Historical data from oil and gas exploration in the delta of the Mackenzie River, Northwest Territories, in the 1970s provided an opportunity to estimate decadal-scale impacts of exploratory oil and gas drilling on native plant communities in low Arctic tundra. We assessed changes in vegetation composition and associated environmental gradients across seven drilling mud sumps in the Kendall Island Bird Sanctuary, Mackenzie Delta. Three decades after disturbance, drilling sumps had developed vegetation coverage equivalent to that in undisturbed areas, although bare soil persisted in ponded areas and where a salt crust was present. Vegetation on sumps was composed of communities dominated by forbs, grasses, and tall shrubs that were distinct from adjacent, undisturbed sedge and low shrub communities. The area of altered vegetation around a sump was generally larger in upland or saline environments than in lowland areas. Pooled water observed around many sumps was likely associated with thaw subsidence that occurred following construction, which was subsequently compounded by snow drifting and increased soil temperatures along the margins of the sump mound. Changes in drainage, active-layer depth, and surface salt concentrations appear to be key environmental factors that have helped shape plant communities established on drilling sumps in the three decades after disturbance.Les données historiques relatives à l’exploration pétrolière et gazière réalisée dans le delta du fleuve Mackenzie, Territoires du Nord-Ouest, dans les années 1970 ont permis d’estimer les incidences décadaires des forages pétroliers et gaziers exploratoires sur les peuplements de végétaux régionaux de la basse toundra arctique. Nous avons évalué les changements caractérisant la composition de la végétation et les gradients environnementaux connexes relativement à sept bassins à boue du refuge d’oiseaux de l’île Kendall, dans le delta du Mackenzie. Trois décennies après la perturbation, la couverture végétale des bassins à boue était équivalente à celle des endroits non perturbés, bien qu’il restait toujours du sol dénudé dans les endroits en présence d’étangs et de croûtes salées. Le végétation se retrouvant sur les bassins était composée d’herbes non graminéennes, de graminées et de grands arbrisseaux différents des peuplements adjacents constitués de laiche et de petits arbrisseaux non perturbés. La zone caractérisée par la nouvelle végétation autour d’un bassin était généralement plus volumineuse dans les hautes terres ou les milieux salins que dans les basses terres. L’eau accumulée autour de nombreux bassins découlait vraisemblablement de la subsidence attribuable au dégel qui s’est manifesté après la construction, ce qui a été aggravé par la poudrerie et les températures du sol à la hausse le long des marges du monticule des bassins. Les changements en matière de ruissellement, de profondeur de la couche active et de concentrations de sel de surface semblent constituer d’importants facteurs environnementaux ayant aidé à façonner les peuplements de végétaux qui se sont établis sur les bassins de forage au cours des trois décennies ayant suivi la perturbation