Modelling and simulation of advanced non-linear autopilot designs

This paper presents the simulation in ESL of a non-linear 6 degree-of-freedom missile model with an advanced, non-linear, multivariable autopilot designed using Rate Actuated Inverse Dynamics (RAID) methods. High performance control of non-linear systems requires the design of advanced, non-linear control systems, such as those used in autopilot design. Traditional linear control system design and analysis techniques are not sufficient for non-linear systems and current non-linear analysis methods are extremely limited. Therefore, the only method available to fully assess the performance of non-linear controller designs is simulation of the non-linear system. For this reason it is an essential part of the analysis and design process of these types of controllers. Non-linear dynamics can be continuous or discontinuous, the aerodynamics of a missile are non-linear but since they are continuous they do not represent a simulation challenge. However, there are multiple sets of discontinuous dynamics present in both the missile control surface model and the autopilot which can lead to multiple discontinuities being reached simultaneously, providing a challenging modeling exercise. The paper demonstrates how this kind of behavior can be successfully modeled and simulated within ESL using a simple switching logic

Conceptualizing teachers' perceptions of Aboriginal student achievement : an exploratory study

ABSTRACT The primary purpose of this study was to explore teachers’ perceptions of Aboriginal student achievement in six Saskatchewan public community schools in urban, rural, and Northern settings. Three of the schools were elementary schools, and three were high schools. Data for the study were obtained by means of teacher semi-structured interviews, and a teacher survey designed expressly for this research. The research opportunity sought to “explore in the context of selected Saskatchewan community schools, teachers’ perceptions of Aboriginal achievement, the unique and contextualized features that govern Aboriginal learning, and the efforts of teachers to enhance Aboriginal student learning.” Historically, Aboriginal student achievement has been viewed through a deficit lens. To gain a positive perspective of this phenomenon, a constructivist paradigm, a social justice theory of change governed by an ethos of appreciative inquiry were employed using a Mixed Methods Research design. Specifically, a two phase exploratory methodology where a qualitative phase followed by a quantitative one was used to best inform the research perspective. A multi-case study approach for each school and division was deemed the most effective means of exploring teacher conceptualizations of the manner and conditions under which Aboriginal students best learn. A total of nine teachers were interviewed and 28 responded to the teacher survey instrument. Member checks of the interview data were undertaken and statistical data using both Excel for Windows as well as SPSS statistical programs were employed for survey data analysis. Owing to the small survey sample, the author advises that caution be used when considering the survey results. However, it is hoped that refinement of the survey tool and its use in later research will prove to be of benefit in understanding the phenomenon of Aboriginal student achievement. A peer data analysis panel was convened to thematically analyse the four open-ended questions contained in the survey. Findings for this study indicated teachers valued the work of collaborative teams, supportive school learning environments, differentiated instruction, assessment for learning, professional development, and culturally responsive instruction and curriculum and school/division alignment to enhance Aboriginal student achievement. The study found that perceptions of Aboriginal and non-Aboriginal teachers differed where Aboriginal student achievement was concerned. As well, participants felt that heightened Aboriginal student achievement could be fashioned by determined student engagement in their academic work. Finally, participants believed that parent and community engagement in schools and the academic life of their children would also enhance Aboriginal student learning outcomes. It is hoped that this study will serve as a point of initiation for more research into the phenomenon on a wider basis in order to generate greater understanding of the means by which Aboriginal students may flourish within public schools in Saskatchewan and potentially elsewhere

Optimization of Annealing Cycles for Electric Output in Outdoor Conditions for Amorphous Silicon Photovoltaic - Thermal Systems

Previous studies with fixed operating temperatures have shown that hydrogenated amorphous silicon (a-Si:H) was a promising absorber layer for solar photovoltaic–thermal (PVT) systems because of (a) a low temperature coefficient and (b) the opportunity to reverse light induced degradation with thermal annealing. This study further refined the simulation of the optimal dispatch strategy for a-Si:H based PVT by studying annealing cycles and analysis of the degradation at other operating temperatures controlled by the varying ambient temperatures. Four representative case studies were evaluated for the combinations of high and low solar flux and high and low average ambient temperature. Electrically-optimized dispatch strategies are found for a range of PVT thermal insulating effectivenesses. The results showed significantly more electricity generation in all the case study representative regions except for areas dominated by low temperatures and low solar fluxes. These results indicate that a-Si:H PV performance can be improved in most populated regions in the world by integrating it into a PVT device and using spike annealing to reverse light-induced degradation effects. The model presented in this paper uses publicly-available data to implement suitable dispatch strategies and execute virtual performance analysis of PVT for any geographic location in the world

ICTs Help Citizens Voice Concerns over Water – Or Do They?

Information and communications technologies (ICTs) are widely seen as a new avenue for citizens to hold service providers and government to account. But if citizens live in rural Africa, Asia or Latin America, are they able and willing to report on service delivery failures? And are service providers or government officials willing to listen and respond? We explore these questions using an analysis of recent ICT reporting initiatives to improve rural water sustainability. The findings demonstrate that models where a service provider is committed to responsiveness and designs an in‑house fault-reporting and maintenance system show greater responsiveness and accountability to users than crowdsourcing models where users are encouraged to report faults. This raises the question of whether ICT is transformative, or whether service improvement simply hinges on making service provision designs more accountable

How can ICT initiatives be designed to improve rural water supply?

Access to water supply around the world is increasing, but poor sustainability of water supply services remains a key barrier, particularly in rural areas. In response to this, a growing number of information and communication technology (ICT) initiatives aim to improve the monitoring and functionality of water supply. Research carried out by WaterAid, IRC and Itad, and supported by Making All Voices Count examines evidence from two water supply monitoring systems involving ICTs in Uganda and Timor Leste to understand how ICT initiatives should be designed to improve rural water supply.UKAID, SIDA, USAID, Omidyar Networ

In Native Worth: Creation

https://digitalcommons.library.umaine.edu/mmb-ps/3386/thumbnail.jp

A Chandra Study of the Effects of a Major Merger on the Structure of Abell 2319

We present an analysis of a Chandra observation of the massive, nearby galaxy cluster Abell 2319. A sharp surface brightness discontinuity--suggested by previous, lower angular resolution X-ray imaging--is clearly visible in the ACIS image. This roughly 300kpc feature suggests that a major merger is taking place with a significant velocity component perpendicular to the line of sight. The cluster emission-weighted mean temperature is 11.8+/-0.6kev, somewhat higher than previous temperature measurements. The Chandra temperature map of A2319 reveals substructure resembling that anticipated based on hydrodynamic simulations of cluster mergers. The merger feature shows a pressure change across the surface brightness discontinuity by a factor of <=2.5. The higher density side of the front has a lower temperature, suggesting the presence of a cold front similar to those in many other merging clusters. The velocity of the front is roughly sonic. We compare bulk properties of the ICM and galaxies in A2319 to the same properties in a large sample of clusters as a way of gauging the effects of the major merger. Interestingly, by comparing A2319 to a sample of 44 clusters studied with the ROSAT PSPC we find that the X-ray luminosity, isophotal size, and ICM mass are consistent with the expected values for a cluster of its temperature; in addition, the K-band galaxy light is consistent with the light--temperature scaling relation derived from a sample of about 100 clusters studied with 2MASS. Together, these results indicate either that the merger in A2319 has not been effective at altering the bulk properties of the cluster, or that there are large but correlated displacements in these quantities.Comment: 11 pages, 8 figures, ApJ Submitte