2,289 research outputs found

    Review of world experience and properties of materials for encapsulation of terrestrial photovoltaic arrays

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    Published and unpublished information relating to encapsulation systems and materials properties was collected by searching the literature and appropriate data bases (over 1,300 documents were selected and reviewed) and by personal contacts including site and company visits. A data tabulation summarizing world experience with terrestrial photovoltaic arrays (50 installations) is presented in the report. Based on criteria of properties, processability, availability, and cost, candidate materials were identified which have potential for use in encapsulation systems for arrays with a lifetime of over 20 years high reliability, an efficiency greater than 10 percent, a total price less than $500/kW, and a production capacity of 500,000 kW/yr. The recommended materials (all commercially available) include, depending upon the device design, various borosilicate and soda-lime glasses and numerous polymerics suitable for specific encapsulation system functions

    Methodology for designing accelerated aging tests for predicting life of photovoltaic arrays

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    A methodology for designing aging tests in which life prediction was paramount was developed. The methodology builds upon experience with regard to aging behavior in those material classes which are expected to be utilized as encapsulant elements, viz., glasses and polymers, and upon experience with the design of aging tests. The experiences were reviewed, and results are discussed in detail

    Development of an Accelerated Test Design for Predicting the Service Life of the Solar Array at Mead, Nebraska

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    Potential long-term degradation modes for the two types of modules in the Mead array were determined and judgments were made as to those environmental stresses and combinations of stresses which accelerate the degradation of the power output. Hierarchical trees representing the severity of effects of stresses (test conditions) on eleven individual degradation modes were constructed and were pruned of tests judged to be nonessential. Composites of those trees were developed so that there is now one pruned tree covering eight degradation modes, another covering two degradation modes, and a third covering one degradation mode. These three composite trees form the basis for selection of test conditions in the final test plan which is now being prepared

    The space shuttle launch vehicle aerodynamic verification challenges

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    The Space Shuttle aerodynamics and performance communities were challenged to verify the Space Shuttle vehicle (SSV) aerodynamics and system performance by flight measurements. Historically, launch vehicle flight test programs which faced these same challenges were unmanned instrumented flights of simple aerodynamically shaped vehicles. However, the manned SSV flight test program made these challenges more complex because of the unique aerodynamic configuration powered by the first man-rated solid rocket boosters (SRB). The analyses of flight data did not verify the aerodynamics or performance preflight predictions of the first flight of the Space Transportation System (STS-1). However, these analyses have defined the SSV aerodynamics and verified system performance. The aerodynamics community also was challenged to understand the discrepancy between the wind tunnel and flight defined aerodynamics. The preflight analysis challenges, the aerodynamic extraction challenges, and the postflight analyses challenges which led to the SSV system performance verification and which will lead to the verification of the operational ascent aerodynamics data base are presented

    Space shuttle high pressure auxiliary propulsion subsystem definition study Subtask B report

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    Space shuttle high pressure, hydrogen oxygen auxiliary propulsion subsystem preliminary desig

    VelociWatch: Designing and evaluating a virtual keyboard for the input of challenging text

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    © 2019 Association for Computing Machinery. Virtual keyboard typing is typically aided by an auto-correct method that decodes a user’s noisy taps into their intended text. This decoding process can reduce error rates and possibly increase entry rates by allowing users to type faster but less precisely. However, virtual keyboard decoders sometimes make mistakes that change a user’s desired word into another. This is particularly problematic for challenging text such as proper names. We investigate whether users can guess words that are likely to cause auto-correct problems and whether users can adjust their behavior to assist the decoder. We conduct computational experiments to decide what predictions to ofer in a virtual keyboard and design a smartwatch keyboard named VelociWatch. Novice users were able to use the features of VelociWatch to enter challenging text at 17 words-per-minute with a corrected error rate of 3%. Interestingly, they wrote slightly faster and just as accurately on a simpler keyboard with limited correction options. Our fnding suggest users may be able to type dif-fcult words on a smartwatch simply by tapping precisely without the use of auto-correct

    Evaluation available encapsulation materials for low-cost long-life silicon photovoltaic arrays

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    Experimental evaluation of selected encapsulation designs and materials based on an earlier study which have potential for use in low cost, long-life photovoltaic arrays are reported. The performance of candidate materials and encapsulated cells were evaluated principally for three types of encapsulation designs based on their potentially low materials and processing costs: (1) polymeric coatings, transparent conformal coatings over the cell with a structural-support substrate; (2) polymeric film lamination, cells laminated between two films or sheets of polymeric materials; and (3) glass-covered systems, cells adhesively bonded to a glass cover (superstrate) with a polymeric pottant and a glass or other substrate material. Several other design types, including those utilizing polymer sheet and pottant materials, were also included in the investigation

    Safety of Arch Aortography for Assessment of Carotid Arteries

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    AbstractPurposeTo retrospectively review the safety of arch aortography and compare complication rates with published figures for selective catheter angiography.MethodsThe medical records of patients undergoing arch aortography over the last 3 years (n=311; 180 male, 131 female; mean±SD age 71.0±9.2 years, range 42–90 years) were retrospectively reviewed. Any peri-procedural (0–48h) complications were recorded. A certified neurologist (MSR/GSV) classified all questionable neurological events.ResultsThere were no focal neurological events or deaths (n=0; 0%; CI: 0–0.96%). Non-focal neurological events included mild disorientation (n=2; 0.6%; CI: 0.176–2.31) and unequal pupils (n=1; 0.3%; CI: 0.056–1.79%). Cardiovascular events included symptomatic hypotension (n=4; 1.3%; CI: 0.50–3.25%), angina (n=1; 0.3%; CI: 0.056–1.79%) and arrhythmia (n=4; 1.3%; CI: 0.50–3.25). There were 27 minor access site complications (8.7%; CI: 6.0–12.3). None of these complications extended hospital stay. None of the arch angiograms had to be followed by selective carotid angiography.ConclusionArch aortography appears to have a lower neurological complication rate than selective carotid angiography
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