16,921 research outputs found
Slicing of silicon into sheet material. Silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project
Fabrication of a prototype large capacity multiple blade slurry saw is considered. Design of the bladehead which will tension up to 1000 blades, and cut a 45 cm long silicon ingot as large as 12 cm in diameter is given. The large blade tensioning force of 270,000 kg is applied through two bolts acting on a pair of scissor toggles, significantly reducing operator set-up time. Tests with an upside-down cutting technique resulted in 100% wafering yields and the highest wafer accuracy yet experienced with MS slicing. Variations in oil and abrasives resulted only in degraded slicing results. A technique of continuous abrasive slurry separation to remove silicon debris is described
Case studies to enhance online student evaluation: Bond University – Surveying students online to improve learning and teaching
One of the most sensible ways of improving learning and teaching is to ask the students for feedback. At the end of each teaching period (i.e. semester or term) all universities and many schools survey their students. Usually these surveys are managed online. Questions ask for student perceptions about teaching, assessment and workload. The survey administrators report four common problems
Energy Conversion Alternatives Study (ECAS), General Electric Phase 1. Volume 2: Advanced Energy Conversion Systems. Part 2: Closed Turbine Cycles
For abstract, see N76-23680
The usefulness of thermal infrared and related imagery in the evaluation of agricultural resources. An exploratory study, volume I Final report
Multispectral imagery for aerial inventory and analysis of cultivated crop resource
An improved perturbation approach to the 2D Edwards polymer -- corrections to scaling
We present the results of a new perturbation calculation in polymer
statistics which starts from a ground state that already correctly predicts the
long chain length behaviour of the mean square end--to--end distance , namely the solution to the 2~dimensional~(2D) Edwards model.
The thus calculated is shown to be convergent in ,
the number of steps in the chain, in contrast to previous methods which start
from the free random walk solution. This allows us to calculate a new value for
the leading correction--to--scaling exponent~. Writing , where in 2D,
our result shows that . This value is also supported by an
analysis of 2D self--avoiding walks on the {\em continuum}.Comment: 17 Pages of Revtex. No figures. Submitted to J. Phys.
Seawater capacitance – a promising proxy for mapping and characterizing drifting hydrocarbon plumes in the deep ocean
Hydrocarbons released into the deep ocean are an inevitable consequence of natural seep, seafloor drilling, and leaking wellhead-to-collection-point pipelines. The Macondo 252 (Deepwater Horizon) well blowout of 2010 was even larger than the Ixtoc event in the Gulf of Campeche in 1979. History suggests it will not be the last accidental release, as deepwater drilling expands to meet an ever-growing demand. For those who must respond to this kind of disaster, the first line of action should be to know what is going on. This includes knowing where an oil plume is at any given time, where and how fast it is moving, and how it is evolving or degrading. We have experimented in the laboratory with induced polarization as a method to track hydrocarbons in the seawater column and find that finely dispersed oil in seawater gives rise to a large distributed capacitance. From previous sea trials, we infer this could potentially be used to both map and characterize oil plumes, down to a ratio of less than 0.001 oil-to-seawater, drifting and evolving in the deep ocean. A side benefit demonstrated in some earlier sea trials is that this same approach in modified form can also map certain heavy placer minerals, as well as communication cables, pipelines, and wrecks buried beneath the seafloor
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Adherence to medication in children and adolescents with asthma: methods for monitoring and intervention
Introduction: Poor adherence in children with asthma is a major cause of asthma attacks and poor control, leads to large health-care costs, and has been identified as a factor in asthma deaths. However, it is difficult to detect and frequently overlooked leading to inappropriate escalation of asthma treatment. There is a need for cost effective ways to monitor adherence in order to intervene to change this modifiable behavior.
Areas covered: Several measurement tools have been developed to assess adherence in adults and children with asthma. The current methods for measuring adherence, both subjective and objective, have several flaws and even the current gold standard, electronic monitoring devices (EMDs), has limitations. This review will outline and critique the adherence monitoring tools and highlight ways in which they have been used for the purpose of intervention.
Expert commentary: Although advances have been made in adherence monitoring, we still have some way to go in creating the ideal monitoring tool. There are no validated tailored self-monitoring questionnaires for children with asthma and most objective measures, such as prescription refill rate and weighing canisters, overestimate adherence. Current EMDs, although useful, need improved accuracy to ensure that both actuation and inhalation are measured, and the devices need to be affordable for use in routine health-care practice
A controlled experiment for the empirical evaluation of safety analysis techniques for safety-critical software
Context: Today's safety critical systems are increasingly reliant on
software. Software becomes responsible for most of the critical functions of
systems. Many different safety analysis techniques have been developed to
identify hazards of systems. FTA and FMEA are most commonly used by safety
analysts. Recently, STPA has been proposed with the goal to better cope with
complex systems including software. Objective: This research aimed at comparing
quantitatively these three safety analysis techniques with regard to their
effectiveness, applicability, understandability, ease of use and efficiency in
identifying software safety requirements at the system level. Method: We
conducted a controlled experiment with 21 master and bachelor students applying
these three techniques to three safety-critical systems: train door control,
anti-lock braking and traffic collision and avoidance. Results: The results
showed that there is no statistically significant difference between these
techniques in terms of applicability, understandability and ease of use, but a
significant difference in terms of effectiveness and efficiency is obtained.
Conclusion: We conclude that STPA seems to be an effective method to identify
software safety requirements at the system level. In particular, STPA addresses
more different software safety requirements than the traditional techniques FTA
and FMEA, but STPA needs more time to carry out by safety analysts with little
or no prior experience.Comment: 10 pages, 1 figure in Proceedings of the 19th International
Conference on Evaluation and Assessment in Software Engineering (EASE '15).
ACM, 201
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