Radiation Damage Workshop report

The starting material, cell design/geometry, and cell processing/fabrication for silicon and gallium arsenide solar cells are addressed with reference to radiation damage. In general, it is concluded that diagnostic sensitivities and material purities are basic to making significant gains in end-of-life performance and thermal annealability. Further, GaAs material characterization is so sketchy that a well defined program to evaluate such material for solar cell application is needed to maximize GaAs cell technology benefits

Results of the Air Force high efficiency cascaded multiple bandgap solar cell programs

The III-V semiconductor materials system that was selected for continued cascade cell development was the AlGaAs cell on GaAs cell structure. The tunnel junction used as transparent ohmic contact between the top cell and the bottom cell continued to be the central difficulty in achieving the program objective of 25 percent AMO efficiency at 25 C. During the tunnel junction and top cell developments it became apparent that the AlGaAs cell has potential for independent development as a single junction converter and is a logical extension of the present GaAs heteroface technology

A review of Air Force high efficiency cascaded multiple bandgap solar cell research and development

At the time of their conception, the cell stack systems to be discussed represent the best semiconductor materials combinations to achieve Air Force program goals. These systems are investigated thoroughly and the most promising systems, from the standpoint of high efficiency, are taken for further development with large area emphasized (at least 4 sq cm). The emphasis in the Air Force cascaded cell program is placed on eventual nonconcentrator application. This use of the final cell design considerably relieves the low resistance requirements for the tunnel junction. In a high concentration application the voltage drop across the tunnel junction can be a very serious problem

Mapping methods and observations of surficial snow/ice cover at Redoubt and Pavlof volcanoes, Alaska using optical satellite imagery

Thesis (M.S.) University of Alaska Fairbanks, 2014Alaska is a natural laboratory for the study of how active volcanism interacts with underlying seasonal snow, perennial snow, and glacial ice cover. While over half of the historically active volcanoes in Alaska have some degree of perennial snow or glacial ice, all Alaskan volcanoes have a covering of seasonal snow for a period of time throughout the year. Previous research has centered on how volcanic deposits erode away the underlying snow/ice cover during an eruption, producing volcanic mudflows called lahars. Less emphasis has been placed on how variations in the snow/ice cover substrate effect the efficiency of meltwater generation during a volcanic eruption. Glacial ice, perennial snow, and seasonal snow can all contribute significantly to meltwater, and therefore the variations in the types of snow/ice cover present at Alaskan volcanoes must be analyzed. By examining the changing spatial extent of seasonal snow present at a volcano during multiple Alaskan summers, the approximate boundaries of perennial snow and ice can be mapped as the snow/ice cover consistently present at the end of each ablation season. In this study, two methods of snow/ice cover mapping for Redoubt and Pavlof volcanoes are analyzed for efficiency and accuracy. Identification of the best method allows for mapping of the snow/ice cover consistently present during each Alaskan summer month over at least two different years. These maps can serve as approximations for the snow/ice cover likely to be present at both volcanoes during each summer month. Volcanic deposits produced during the 2009 Redoubt and 2013 Pavlof eruptions are spatially linked to these snow/ice cover maps so that future research can focus on the interaction between deposits and type of snow/ice substrate. Additional observations and conclusions are made regarding how the visible snow/ice cover varies during and after each eruption.Chapter 1. Introduction -- 1.1. Background -- 1.2. Comparison of snow/ice cover mapping methods for Alaskan volcanoes -- 1.3. Mapping snow/ice on Redoubt and Pavlof during quiescence and eruption -- 1.4. Summary of final outcomes -- 1.5. References -- Chapter 2. Methods for snow/ice cover mapping of Redoubt and Pavlof volcanoes using optical satellite imagery -- 2.1. Introduction -- 2.1.1. Satellite remote sensing of glaciers and snow cover in Alaska -- 2.1.2. Previous work and methods for studying snow/ice on volcanoes -- 2.1.3. Challenges of mapping snow/ice cover at Alaskan volcanoes -- 2.2. Setting of Redoubt volcano -- 2.2.1. Basic setting of Redoubt volcano -- 2.3. Setting of Pavlof volcano -- 2.3.1. Basic setting of Pavlof volcano -- 2.4. Methods -- 2.4.1. Previous work in snow/ice cover mapping using satellite imagery -- 2.4.2. Sensors used for snow/ice cover mapping -- 2.4.3. Pre-processing of satellite imagery -- 2.4.4. Methods used to map snow/ice cover at Redoubt and Pavlof -- 2.4.5. Technique 1: band ratios -- 2.4.6. Technique 2: principal component analysis -- 2.4.7. Technique 3: linear spectral unmixing -- 2.5. Results and discussion -- 2.5.1. Snow/ice cover mapping using threshold method -- 2.5.2. Snow/ice cover mapping using linear spectral unmixing method -- 2.5.3. Improvements to linear spectral unmixing method for snow/ice cover mapping -- 2.5.4. Validation of results -- 2.6. Conclusion -- 2.7. Figures -- 2.8. Tables -- 2.9. References -- Chapter 3. Observations of surficial snow/ice cover changes due to seasonal and eruptive influences on Redoubt and Pavlof volcanoes, Alaska using optical remote sensing -- 3.1. Introduction -- 3.1.1. Alaskan volcanoes -- 3.2. Volcano-snow/ice interactions -- 3.2.1. Short term interactions -- 3.2.2. Long term interactions -- 3.2.3. Lahar formation and hazards -- 3.2.4. Influence of snow/ice substrate type on lahar generation -- 3.3. Background on Redoubt volcano -- 3.3.1. Setting of Redoubt volcano -- 3.3.2. Recent eruptions at Redoubt volcano -- 3.3.3. Eruption effects on Drift Glacier -- 3.3.4. Lahar hazards at Redoubt volcano -- 3.4. Background on Pavlof volcano -- 3.4.1. Setting of Pavlof volcano -- 3.4.2. Recent eruptions at Pavlof volcano -- 3.4.3. Lahar hazards at Pavlof volcano -- 3.5. Methods -- 3.5.1. Sensors used to create Products 1, 2, and 3 -- 3.5.2. Methods used to produce Product 1: individual snow/ice cover maps -- 3.5.3. Methods used to produce Product 2: snow/ice cover summary maps -- 3.5.4. Methods used to produce Product 3: composite maps of eruptive deposits and snow/ice cover -- 3.6. Results and discussion -- 3.6.1. Product 1: individual snow/ice cover maps of Redoubt subset -- 3.6.2. Product 2: snow/ice cover summary maps of Redoubt subset -- 3.6.3. Product 3: composite maps of eruptive deposits and snow/ice cover of Redoubt subset -- 3.6.4. Product 1: individual snow/ice cover maps of Pavlof subset -- 3.6.5. Product 2: snow/ice cover maps of Pavlof subset -- 3.6.6. Product 3: composite maps of eruptive deposits and snow/ice cover of Pavlof subset -- 3.7. Conclusion -- 3.8. Figures -- 3.9. Tables -- 3.10. References -- Chapter 4. Conclusion -- 4.1. Comparison of snow/ice cover mapping methods for Alaskan volcanoes -- 4.2. Mapping snow/ice on Redoubt and Pavlof during quiescence and eruption -- 4.3. Limitations and future work -- 4.4. References

Value of Exemption from Professional Examinations: Opinion of Third-Level Accounting Students and Graduates

In Ireland (and the UK) becoming an accountant usually involves a dual qualification system: a third-level degree followed by training and professional examination. This is commonly conceptualised as learning through knowing followed by learning through doing (Wilson, 2011; Apostolou & Gammie, 2014). Much debate exists about where the responsibility for the development of knowledge and skills lies. Third-level accounting degrees have been criticised for focusing too much on gaining exemptions from professional examinations, with employers feeling that graduates are not work ready (Albrecht & Sack, 2000; Jackling & De Lange, 2008; Pan & Perera, 2012; Bayerlein & Timpson, 2017). However, anecdotally, students and graduates value exemptions and maximising exemption is important to them. This study explores the views of third-level accounting students and recent graduates to confirm (or not) if exemptions are valued by students and graduates. Mixed methods were used in this study. Fifteen in-depth interviews were conducted; ten with third-level accounting students and five with recent accounting graduates. The findings from these interviews were supported by information obtained from a survey which had eighty-three respondents; fifty-three students and thirty graduates. All participants expressed a strong preference for gaining exemptions during their degree to expedite qualification. While the development of broader business skills was acknowledged as useful, neither students nor graduates were willing to replace exemption bearing modules. Even though graduates admit to not having all the generic skills needed to be work-ready, both students and graduates were in agreement that exemption-led modules provide the most relevant knowledge for professional life. Students valued exemptions because they believed earning exemptions improves the work-life balance of the accounting graduate during the period of professional training and examination. Exemptions were seen as reducing the effort required by graduates to achieve qualification. Graduates after beginning professional examinations were less concerned about balancing work and study. Instead they view exemptions as having helped to improve employability prospects. Students and graduates believe that earning exemptions demonstrates to employer’s the graduates’ commitment to their career and willingness (and capability) to complete professional training and examinations. Findings from this study provide qualitative evidence that exemptions are highly valued by accounting students and graduates. Awareness of exemptions should be promoted at the earlier stages of the accounting degree. Graduates did see a lot of benefit from a broader curriculum making students more work ready. Educators should continue to investigate ways of improving generic skills without removing exemptions. Developing broader business skills could be introduced as methods of examining modules (such as group work, presentations and IT reports), rather than replacing exemption-bearing modules

Derivation of the Diffusion Equation and a Revision of Matsuda\u27s Theory for Polarography

Many theories have been proposed to yield a current-time relationship in Polarography. The most widely accepted is that of Matsuda. He assumes that the electrolyte can be separated into an inhomogeneous region about the mercury drop and a homogeneous region elsewhere. This assumption leads to a first order , nonlinear, ordinary differential equation directly solvable by substitution of a properly chosen series. But the series solution obtained is only a particular solution; for there exists, as one would expect, a family of solutions depending on a contrast of integration. In the literature, derivation of the diffusion equation has never been attacked from the standpoint that the diffusion processes are occurring with respect to the medium. The convection term in the accepted diffusion equation is introduced as a generalization to account for the growth of the mercury drop. This paper will show that the function describing the concentration of diffusing ions need not be broken up into two separate parts. Integration will be carried out an infinite distance rather than from the surface of the mercury drop out distance 0. The series solution is only one of many solutions. A solution obtained by using an experimental value for an initial 0 will compare favorably with experiment. Also, derivation of a diffusion equation based on diffusion with respect to the medium will be given

Grown-in defects and defects produced by 1-Me electron irradiated in Al0.3Ga0.7As P-N junction solar cells

Studies of grown-in defects and defects produced by the one-MeV electron irradiation in Al sub 0.3 Ga sub 0.7As p-n junction solar cells fabricated by liquid phase epitaxial (LPE) technique were made for the unirradiated and one-MeV electron irradiated samples, using DLTS and C-V methods. Defect and recombination parameters such as energy level, defect density, carrier capture cross sections and lifetimes were determined for various growth, annealing, and irradiation conditions

Reasoning About a Simulated Printer Case Investigation with Forensic Lucid

In this work we model the ACME (a fictitious company name) "printer case incident" and make its specification in Forensic Lucid, a Lucid- and intensional-logic-based programming language for cyberforensic analysis and event reconstruction specification. The printer case involves a dispute between two parties that was previously solved using the finite-state automata (FSA) approach, and is now re-done in a more usable way in Forensic Lucid. Our simulation is based on the said case modeling by encoding concepts like evidence and the related witness accounts as an evidential statement context in a Forensic Lucid program, which is an input to the transition function that models the possible deductions in the case. We then invoke the transition function (actually its reverse) with the evidential statement context to see if the evidence we encoded agrees with one's claims and then attempt to reconstruct the sequence of events that may explain the claim or disprove it.Comment: 18 pages, 3 figures, 7 listings, TOC, index; this article closely relates to arXiv:0906.0049 and arXiv:0904.3789 but to remain stand-alone repeats some of the background and introductory content; abstract presented at HSC'09 and the full updated paper at ICDF2C'11. This is an updated/edited version after ICDF2C proceedings with more references and correction

Actes du Congrès Collèges célébrations 92

Également disponible en version papierTitre de l'écran-titre (visionné le 14 août 2009)Bibliogr.: p.

Decision-making in percutaneous coronary intervention: a survey

<p>Abstract</p> <p>Background</p> <p>Few researchers have examined the perceptions of physicians referring cases for angiography regarding the degree to which collaboration occurs during percutaneous coronary intervention (PCI) decision-making. We sought to determine perceptions of physicians concerning their involvement in PCI decisions in cases they had referred to the cardiac catheterization laboratory at a major academic medical center.</p> <p>Methods</p> <p>An anonymous survey was mailed to internal medicine faculty members at a major academic medical center. The survey elicited whether responders perceived that they were included in decision-making regarding PCI, and whether they considered such collaboration to be the best process of decision-making.</p> <p>Results</p> <p>Of the 378 surveys mailed, 35% (133) were returned. Among responding non-cardiologists, 89% indicated that in most cases, PCI decisions were made solely by the interventionalist at the time of the angiogram. Among cardiologists, 92% indicated that they discussed the findings with the interventionalist prior to any PCI decisions. When asked what they considered the best process by which PCI decisions are made, 66% of non-cardiologists answered that they would prefer collaboration between either themselves or a non-interventional cardiologist and the interventionalist. Among cardiologists, 95% agreed that a collaborative approach is best.</p> <p>Conclusion</p> <p>Both non-cardiologists and cardiologists felt that involving another decision-maker, either the referring physician or a non-interventional cardiologist, would be the best way to make PCI decisions. Among cardiologists, there was more concordance between what they believed was the best process for making decisions regarding PCI and what they perceived to be the actual process.</p