128 research outputs found
Effects of pendent phenol functional groups on secondary coordination spheres of heme like Fe-salen complexes
No full textSince the beginning of industrial revolution, burning of fossil fuels has mainly led to increase in atmospheric concentration of CO2 , a Green House Gas (GHG), from 250 ppm to 400 ppm between 1800 and 2012. One way to reduce the burning of fossil fuels and CO2 emission rate is to explore alternative carbon free fuels to meet the energy demand.This project aims at the synthesis and study of metal complexes inspired by biological models that will help better design catalysts to perform water oxidation more effectively.This poster won the Dean, Faculty of Science award (2020). Advisor: Dr. Linus Chiang, Departmen of Chemistry
Power-to-X-to-Power in Combined Cycle Power Plants : A Techno-Economic Feasibility Study
No full textTo support the largescale integration of renewables in electricity grids, powertoXtopower (P2X2P) systems have been proposed. These systems serve to increase the flexibility of thermal power plants while potentially providing both economic and environmental benefits by allowing power from the plant to be redirected into an electrolyzer and converted to a gaseous energy carrier. In this study, the feasibility of a P2X2P system consisting of a combined cycle gas turbine (CCGT) power plant coupled with a PEM electrolyzer in the Italian power sector has been investigated. A dynamic technoeconomic model has been developed for both hydrogen and ammoniabased systems together with a profit maximizing dispatch strategy for operation in both day-ahead and balancing electricity markets. As a part of this, a PEM electrolyzer model was also developed and validated against experimental data. Notable technical improvements were observed as a consequence of the implementation of a P2X2P system in the form of avoided shutdowns and a more even power output. However, any economic and environmental benefits of such improvements were not observed as the addition of the P2X2P system led to a reduction in net present value as well as higher specific emissions of carbon dioxide. When the gaseous energy carrier was utilized as fuel in the CCGT, similar technical performances were achieved by the hydrogenbased and ammoniabased systems. Due to the increased investment cost demanded by the ammonia production process the hydrogenbased system thus seems most suitable for this setup.För att möjliggöra en storskalig utbyggnad av förnyelsebar energi har powertoXtopowersystem (P2X2P) föreslagits som en potentiell lösning. Genom att omdirigera electricitet från kraftverket till en elektrolysator och därmed omvandla denna till vätgas kan dessa system förbättra den tekniska flexibiliten hos värmekraftverk samtidigt som de har potential att medföra både ekonomiska och miljömässiga fördelar. Detta examensarbete har undersökt den teknoekonomiska potentialen hos ett P2X2Psystem bestående av ett gaskombikraftverk i anslutning till en elektrolysator i det italienska kraftnätet. En dynamisk, teknoekonomisk modell av både vätgas och ammoniakbaserade P2X2Psystem samt en vinstmaximerande kontrollstrategi har utvecklats. En modell över en PEMelektrolysator har även utvecklats och validerats gentemot experimentella data. Införandet av ett P2X2Psystem till kraftverket påvisade en teknisk förbättringspotential genom ett minskat antal uppstarter samt en mer jämn uteffekt. Huruvida denna tekniska förbättring också medför ekonomisk and miljömässig förbättring eller ej kvarstår att påvisa. Detta då nuvärdet minskade samtidigt som koldioxidutsläppen per producerad kilowatttimme ökade vid införandet av P2X2Psystemet. Då den producerade energibäraren, i form av vätgas eller ammoniak, enbart användes för att ersätta fossilgas som bränsle i kraftverket påvisades marginell skillnad i presetanda mellan de två systemen. De större kostnaderna som medförs av ett ammoniakbaserat system pekar därför på att ett vätgasbaserat system vore att föredra under sådana förutsättningar
21st-century scholarship and Wikipedia
No full textWikipedia, the world’s fifth most-used Web site, is a good illustration of the growing credibility of online resources. In his article in Ariadne earlier this year, “Wikipedia: Reflections on Use and Academic Acceptance”, Brian Whalley described the debates around accuracy and review, in the context of geology. He concluded that ‘If Wikipedia is the first port of call, as it already seems to be, for information requirement traffic, then there is a commitment to build on Open Educational Resources (OERs) of various kinds and improve their quality.’ In a similar approach to the Geological Society event that Whalley describes, Sarah Fahmy of JISC worked with Wikimedia and the British Library on a World War One (WWI) Editathon. There is a rich discourse about the way that academics relate to Wikipedia
Optimization of solar panels : A study of optimal use of solar panels based on solar tracking, panel placement and shadowing
No full textDetta kandidatexamensarbete undersöker hur man på optimalt vis använder solpaneler i syfte att producera största möjliga mängd energi samt hur dessa kan generera största möjliga intäkter. Detta görs genom att jämföra solföljande och stationära paneler. Det har även undersökts huruvida geografisk plats har en påverkan på effekten av solföljning. Detta har gjorts genom att studera både Stockholm och München. Optimal uppställning av ett system av solpaneler inom en begränsad area samt effekten av både intern och extern smal skuggning är ytterligare områden som undersöks i detta arbete. Resultaten om solföljningens effekt samt optimal uppställning av panelerna i ett system av solpaneler har tagits fram genom simuleringar i Matlab. Resultaten kring effekten av skuggning har tagits fram genom en litteraturstudie samt experimentella mätningar. Studien visar att användning av solföljande paneler i Stockholm ökar energiproduktionen hos en solpanel med 39,2 % för solföljning i två dimensioner respektive 36,4 % i en dimension, medan ökningen i München blir något lägre med 27,1 % respektive 23,7 %. Utöver detta togs även två alternativa optimala ekonomiska scenarier fram för ett system av solpaneler på en begränsad yta. Antingen täcks hela takytan med horisontellt placerade paneler eller så placeras paneler i sex rader med en lutningsvinkel på 21 grader. Undersökningen av externa smala skuggors effekt på en solpanel tydde på att de skuggor som täckte fler av en solpanels slingor var de skuggor som hade påtaglig effekt på energiproduktionen. De slutsatser som dras utifrån dessa resultat är att solföljande solpaneler är värda att investera i, men att det ur ekonomisk synpunkt inte vore rimligt att installera solföljning i mer än en dimension. Av de två alternativa scenarierna för installation av solpaneler på en begränsad yta anses sex rader med en lutningsvinkel på 21 grader vara det mer realistiska alternativet då de begränsningar som applicerades på modellen som användes för att ta fram detta närmare motsvarar verkligheten. På grund av att smala skuggor som endast täcker en slinga av celler på en solpanel inte orsakade någon betydande effektminskning rekommenderas att de solpaneler som undersökts installeras på så vis att slingorna ligger vertikalt och därför löper lägre risk att flera slingor skuggas samtidigt, då de flesta naturligt förekommande skuggor är vertikala.This bachelor's thesis examines how to use solar panels in the most optimal way in order to produce the largest possible amount of energy and to generate the highest possible revenue. This is done by comparing sun tracking and stationary solar panels. Whether geographical location has an impact on the effect of sun tracking has also been examined. This has been done by studying both Stockholm and Munich. The optimal arrangement of a system of solar panels within a limited area as well as the effect of both internal and thin external shadows are further areas that this work examines. The results of the effect of solar tracking and the optimal arrangement of the panels in a system of solar panels have been produced through simulations in Matlab. Through a literature review and experimental measurements, the results of the effect of shading have been produced. The study shows that the use of solar tracking panels in Stockholm increases the energy production of a solar panel by 39.2 % for solar tracking in two dimensions and 36.4 % in one dimension, while the increase in Munich is somewhat lower at 27.1 % and 23.7 %, respectively. In addition to this, two alternative optimal economic scenarios were found for a system of solar panels within a limited area. Either the entire roof surface is completely covered with horizontally placed panels or panels are placed in six rows with an inclination angle of 21 degrees. The study of the effects of external thin shadows on a solar panel indicated that the shadows that covered several of the solar panel's loops of cells were the shadows that had a significant effect on energy production. The conclusions drawn from these results are that sun tracking solar panels are worth investing in. However, from an economic point of view it would not be reasonable to install solar tracking in more than one dimension. Out of the two alternative scenarios for installing solar panels on a limited surface, six rows with an inclination angle of 21 degrees is considered the more realistic alternative since the limitations applied on the model used to produce this scenario more closely emulates reality. Due to the fact that thin shadows covering only one loop of cells on a solar panel did not cause any considerable power reduction, it is recommended that the studied solar panel is to be installed in such a way that the loops lie vertically and therefore lower the risk of multiple loops being shaded simultaneously, since most naturally occurring shadows are vertical
How Many Answers Are Enough? Optimal Number of Answers for Q&A Sites
No full textWith the proliferation of the social web, questions about information quality and optimization attract the attention of IS scholars. Question-answering (QA) sites, such as Yahoo!Answers, have the potential to produce good answers, but at the same time not all answers are good and not all QA sites are alike. When organizations design and plan for the integration of question answering services on their sites, identification of good answers and process optimization become critical. Arguing that ‘given enough answers all questions are answered successfully,’ this paper identifies the optimal number of posts that generate high quality answers. Based on content analysis of Yahoo! Answers’ informational questions (n=174) and their answers (n=1,023), the study found that seven answers per question are ‘enough’ to provide a good answer
Optimising power-to-gas integration with wastewater treatment and biogas: A techno-economic assessment of CO2 and by-product utilisation
No full textProduction of electrolytic hydrogen and its conversion to methane, also known as power-to-gas (PtG), could play a key role in the transition towards a defossilised energy system. Integration of PtG technology with wastewater treatment and co-digestion presents an opportunity to produce low-carbon methane while simultaneously upgrading biogas, recycling biogenic carbon dioxide and utilising process by-products (heat and oxygen). A model of such an integrated system was developed using real plant data to assess the techno-economic performance through simulation of hourly operation and configuration optimisation. The integrated concept was demonstrated to be a promising option for increasing efficiency and reducing costs and emissions in the PtG system. By-product utilisation increased net energy efficiency from 52.3 to 59.7 %(HHV), leading to a reduction in levelised cost of PtG (LCOPtG) of 1.0 % and in net specific emissions of 28.3 % and 2.2 % based on average and marginal grid emission factors respectively. Minimum LCOPtG of 194.6 /MWh(CH4) was achieved, which entailed average and marginal net specific emissions of 37.2 and 635.2 gCO(2)/kWh(CH4), respectively. In the investigated conditions, the optimised PtG configuration produced heat in excess, but could not fulfil oxygen demand at the wastewater treatment plant. Heat integration yielded considerable performance improvements, while oxygen integration provided only minor benefits and slightly increased overall production costs. However, improved economic performance of oxygen integration was shown to be possible depending on local conditions. Although integrating several independent systems introduced the challenge of managing fluctuating heat and oxygen demand, alongside the varying supply of biogas and renewable electricity, the difference in magnitude between by-product generation and demand meant that their utilisation had only a minor impact on system operation
Power Relations and Social Classes in Pengakuan Pariyem by Linus Suryadi AG: Reflection of Masculine Ideology
No full textThe study aims to explore power relations and social classes as the reflections of the masculine ideology of the author in the novel Pengakuan Pariyem by Linus Suryadi AG. The theories implemented in the study are van Dijk’s power relations and social classes theory and Connell’s masculinity theory. The study is qualitative descriptive and applies the Critical Discourse Analysis (CDA) method, used to dismantle the ideology that is produced and reproduced through the language within the novel. The research data are lingual units that indicate power relations and social classes which simultaneously reflect the notion of masculinity. The results of the study are as follows. First, Pariyem as the central character in the novel lives within a hierarchical and dualistic Javanese society. Her submission as the babu (housemaid) of a priyayi (noble) family does not only lead Pariyem to be dominated symbolically, but also legitimizes the priyayi (aristocrats) power over wong cilik (commoners). It is reinforced by the representations of the priyayis’ world views in terms of culture, aristocracy, bureaucracy, and education orientation. It shows that priyayis are culturally dominant. Secondly, since Pariyem is a character created by a male author, her behaviors and actions reflect the ideology of masculinity. Rather than voicing women, the power relations that Pariyem experiences through the events constructed in the novel show that she embodies the masculine ideology, or masculinity.
Linus Pauling.
No full textDigital ImageAmerican chemist, biochemist, peace activist and author. For his scientific work, Pauling was awarded the Nobel Prize in Chemistry in 1954; and for his peace activism, he was awarded the Nobel Peace Prize in 1962
March for Science: Sign with a quote from scientists Linus Pauling, E. Pine St. at Belmont Ave., Seattle, Washington, April 22, 2017
No full textText on signs read: "No science = No hops, no malt, no water, no beer [the letters in the word beer are made up of periodic element symbols]"; "Facts are the air of scientists. Without them you can never fly. - Linus Pauling. Science, not silence".
Linus Carl Pauling was an American chemist, biochemist, peace activist, author, and educator.
PH Coll 1478. KinseyK116The Seattle March for Science occurred on April 22, 2017. This date was chosen because April 22 is also Earth Day. According to organizers, as many as 20,000 people attended the march, which began at 10 a.m. in Cal Anderson Park in the Capitol Hill neighborhood. The march culminated at the International Fountain at the Seattle Center. The March for Science in Seattle was one of more than 500 similar marches taking place across the United States. Demonstrators marched in support of “robustly funded and publicly communicated science and evidence as a pillar of human freedom and prosperity” and also called “for science that upholds the common good, and for political leaders and policymakers to enact evidence-based policies in the public interest”, according to a statement put out by march organizers. Washington Governor Jay Inslee and Seattle Mayor Ed Murray came out to show their support.Scienc
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