Analysis and modeling of the rear side of industrial-type passivated emitter and rear silicon solar cells

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Feasibility study of collaborative design-build curriculum

The design-build method of project delivery is the most preferred by owners. Almost 40 percent of all buildings are currently produced in this manner, and this trend is not likely to change. Owners prefer the single source organization and responsibility design-build offers and projects are often delivered faster, cheaper, and at a higher level of quality. Design-build project delivery was formerly considered unethical architectural practice by the AIA. However, increasing demand for this service has forced the profession to redefine itself to respond to market conditions. Architects are now in danger of losing the control necessary to ensure their designs are constructed in the way they were conceptualized due to reluctance to accept risk. There is equal opportunity for architect led and contractor led design-build. Most architects have elected not to establish themselves as leaders in the design-build arena. If this trend continues, it is likely that the majority of architects will find themselves working as an aesthetic consultant to the builder rather than acting as a project leader. It is also likely, that in this situation, design quality will succumb to ease of construction and cheaper alternatives. Architectural education needs to respond to the conditions of today\u27s marketplace. Schools should offer students the opportunity to explore design-build and encourage them to become leaders who establish control of the process. Using the Jewell Golf and Country Club, a recent design-build student project, as a case study, I evaluate the potential for converting the present department of architecture thesis track into an optional design-build track. A study of this first attempt at the process will be used to make conclusions about the validity of this program

Simulation-based Efficiency Gain Analysis of 21.2%-efficient Screen-printed PERC Solar Cells

Passivated Emitter and Rear Cells (PERC) with efficiencies well above 20% are likely to become the next mass production technology. A quantification of all power loss mechanisms of such industrial PERC cells is helpful in prioritizing future efficiency improvement measures. We report on a numerical simulation of the power losses of a 21.2%-efficient industrial PERC cell using extensive experimental input data. Our synergetic efficiency gain analysis relies on deactivating single power loss mechanisms in the simulation at a time to access the full potential power gain related to that mechanism. The complete analysis therefore explains the efficiency gap between the industrial PERC solar cell and the theoretical maximum efficiency of a crystalline Si solar cell. Based on the simulations, the largest single loss mechanism is front grid shadowing followed by recombination in the emitter and its surface. All individual resistive losses, all individual optical losses and all (avoidable) individual recombination losses sum up to efficiency gains of 0.8%, 1.6%, and 1.3%, respectively, which is 3.7% in total. The efficiency gap between real and ideal solar cell is, however, much larger with 7.3%. The discrepancy is mainly due to the non-linear behaviour of recombination-based power losses which adds synergetic efficiency enhancements

Encouraging Pro-Environmental Behaviour: Affordances and Institutional Logics in IS-enabled Organisational Sustainability Transformations

While many studies have addressed encouraging employees’ pro-environmental behaviour (PEB) in the workplace, the roles of structures and institutions have received little attention and thus re-main unclear. We draw on the concept of affordances as being enacted and embedded in institu-tional logics, which provide a frame of reference for individual and organisational behaviours. Given our emphasis on organisational sustainability transformations, we explain how organisa-tions can encourage their employees to act pro-environmentally in the workplace with the help of green information systems (Green IS). We address technological, organisational, and human fac-tors that strengthen PEB. Thus, we respond to the call to bring together institutional logics and affordance theory. We present preliminary findings of 55 semi structured interviews with inform-ants from 20 companies, along with internal and external documents. This allows us to develop a pro-environmental corporate logic, which guides employees’ PEB in our case companies. These preliminary findings allow us to develop a research agenda on the interplay of this institutional logic and motivational affordances. We conclude with an outlook on how to tackle the emerging research questions

Entdeckungen zu Internet, Totalreflexion und Farbenlehre in der Optik

Die Jugendlichen wachsen heutzutage mit digitalen Medien auf. Aber verstehen sie diese auch? Wissen sie, wie die Daten zu ihren Endgeräten gelangen? Was kann das Fach Physik zur Beantwortung solcher Fragen beitragen? Wir stellen hierzu eine kleine Unterrichtseinheit bestehend aus zweimal 45 min vor. Darin erkunden Lernende einer sechsten Klasse mit einem Modellversuch den Einsatz mehrerer Farbkanäle im schnellen Internet

Entdeckungen zu Internet, Totalreflexion und Farbenlehre in der Optik

Die Jugendlichen wachsen heutzutage mit digitalen Medien auf. Aber verstehen sie diese auch? Wissen sie, wie die Daten zu ihren Endgeräten gelangen? Was kann das Fach Physik zur Beantwortung solcher Fragen beitragen? Wir stellen hierzu eine kleine Unterrichtseinheit bestehend aus zweimal 45 min vor. Darin erkunden Lernende einer sechsten Klasse mit einem Modellversuch den Einsatz mehrerer Farbkanäle im schnellen Internet

Wet chemical polishing for industrial type PERC solar cells

Industrial PERC cell process flows typically apply the polishing of the rear side after texturing as well as the edge isolation after POCl3 diffusion. In this paper, we present a novel single step polishing process which we apply post double sided texturing and diffusion in order to remove the rear emitter and to reduce the rear surface roughness. One challenge is to minimize the etch back of the front side emitter during rear side polishing due to the reactive gas phase of the polishing process. By optimizing the polishing process, we are able to limit the increase of the emitter sheet resistance below 5 Ω/sq. However, the wet cleaning post polishing contributes an additional 20 Ω/sq emitter sheet resistance increase which is subject to further optimization. We compensate the emitter sheet resistance increase due to wet cleaning by applying a 45 Ω/sq POCl3 diffusion instead of a 60 Ω/sq diffusion. The resulting PERC solar cells with polished rear surface post texture and diffusion show conversion efficiencies up to 19.6% which is comparable to the reference PERC cells which apply a rear protection layer instead of a polishing process.German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety/0325296Heraeus Precious MetalsRenaSingulus TechnologiesSolar Worl

Analysis of the interaction of Spray G and in-cylinder flow in two optical engines for late gasoline direct injection

This is the author's version of a work that was accepted for publication in International Journal of Engine Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published as https://doi.org/10.1177/1468087419881535.[EN] An investigation of the interaction between the in-cylinder flow and the spray topology in two spray-guided direct injection optical engines is reported. The bulk flow field in the combustion chamber is characterized using particle image velocimetry. Geometrical parameters such as the axial penetration and the spray angle of the liquid spray are measured using Mie scatter imaging and/or diffuse back-illumination. The measured parameters are compared with data from a constant volume chamber available in the literature. For a late injection strategy, the so-called ECN Spray G standard condition, the mean values of the spray penetration do not seem to be significantly perturbed by the in-cylinder flow motion until the plumes approach the piston surface. However, spray probability maps reveal that cycle-to-cycle fluctuations of the spatial distribution of the liquid spray are affected by the magnitude of the in-cylinder flow. Particle image velocimetry during injection shows that the flow field in the vicinity of the spray plumes is heavily influenced by air entrainment, and that an upward flow in-between spray plumes develops. Consistent with previous research that demonstrated the importance of the latter flow structure for the prevention of spray collapse, it is found that increased in-cylinder flow magnitudes due to increased intake valve lifts or engine speeds enhance the spray-shape stability. Compared with cases without injection, the influence of the spray on the in-cylinder flow field is still noticeable approximately 2.5 ms after the start of injection.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The work at UDE was funded by the Research Association for Combustion Engines eV (FVV, Frankfurt/Main, project 1203). TUD kindly acknowledges generous support by Deutsche Forschungsgemeinschaft through SFB/Transregio 150 (project number 237267381-TRR150).Geschwindner, C.; Kranz, P.; Welch, C.; Schmidt, M.; Bohm, B.; Kaiser, SA.; De La Morena, J. (2020). 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Advances and challenges in explaining fuel spray impingement: How much of single droplet impact research is useful? Progress in Energy and Combustion Science, 36(5), 554-580. doi:10.1016/j.pecs.2010.01.002Oh, H., & Bae, C. (2013). Effects of the injection timing on spray and combustion characteristics in a spray-guided DISI engine under lean-stratified operation. Fuel, 107, 225-235. doi:10.1016/j.fuel.2013.01.019Park, C., Kim, S., Kim, H., & Moriyoshi, Y. (2012). Stratified lean combustion characteristics of a spray-guided combustion system in a gasoline direct injection engine. Energy, 41(1), 401-407. doi:10.1016/j.energy.2012.02.060Stiehl, R., Schorr, J., Krüger, C., Dreizler, A., & Böhm, B. (2013). In-Cylinder Flow and Fuel Spray Interactions in a Stratified Spray-Guided Gasoline Engine Investigated by High-Speed Laser Imaging Techniques. Flow, Turbulence and Combustion, 91(3), 431-450. doi:10.1007/s10494-013-9500-xPiock, W. F., Befrui, B., Berndorfer, A., & Hoffmann, G. (2015). Fuel Pressure and Charge Motion Effects on GDi Engine Particulate Emissions. SAE International Journal of Engines, 8(2), 464-473. doi:10.4271/2015-01-0746Fansler, T. D., Reuss, D. L., Sick, V., & Dahms, R. N. (2015). Invited Review: Combustion instability in spray-guided stratified-charge engines: A review. International Journal of Engine Research, 16(3), 260-305. doi:10.1177/1468087414565675Drake, M. C., & Haworth, D. C. (2007). Advanced gasoline engine development using optical diagnostics and numerical modeling. Proceedings of the Combustion Institute, 31(1), 99-124. doi:10.1016/j.proci.2006.08.120Fansler, T. D., Stojkovic, B., Drake, M. C., & Rosalik, M. E. (2002). Local fuel concentration measurements in internal combustion engines using spark-emission spectroscopy. Applied Physics B: Lasers and Optics, 75(4-5), 577-590. doi:10.1007/s00340-002-0954-0Peterson, B., Reuss, D. L., & Sick, V. (2014). On the ignition and flame development in a spray-guided direct-injection spark-ignition engine. Combustion and Flame, 161(1), 240-255. doi:10.1016/j.combustflame.2013.08.019Schiffmann, P., Reuss, D. L., & Sick, V. (2017). Empirical investigation of spark-ignited flame-initiation cycle-to-cycle variability in a homogeneous charge reciprocating engine. International Journal of Engine Research, 19(5), 491-508. doi:10.1177/1468087417720558Sementa, P., Maria Vaglieco, B., & Catapano, F. (2012). Thermodynamic and optical characterizations of a high performance GDI engine operating in homogeneous and stratified charge mixture conditions fueled with gasoline and bio-ethanol. Fuel, 96, 204-219. doi:10.1016/j.fuel.2011.12.068Song, J., & Park, S. (2015). EFFECT OF INJECTION STRATEGY ON THE SPRAY DEVELOPMENT PROCESS IN A SINGLE-CYLINDER OPTICAL GDI ENGINE. Atomization and Sprays, 25(9), 819-836. doi:10.1615/atomizspr.2015012018Parrish, S. E., Zhang, G., & Zink, R. J. (2012). 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Dental Fluoride Varnish Application During Medical Visits Among Children Who Are Privately Insured

This cross-sectional study examines fluoride varnish application rates during well-child medical visits and identify characteristics associated with fluoride varnish receipt