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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Effectiveness of Engineered and Natural Wastewater Treatment Processes for the Removal of Trace Organics in Water Reuse

Cheng, Long, Cheng, Long January 2017 (has links)
Due to their potential health impact on human beings and ecosystems, persistent trace organic compounds (TOrCs) have aroused concern from both the public and professionals. In particular, the discharge of pharmaceuticals, endocrine disrupters, disinfection byproducts and other TOrCs from wastewater treatment plants into the environment is an area of extensive current research. This work studies the fate and treatments of TOrCs, with emphases on advanced oxidation processes (AOPs). This work presents predicted removal efficiencies of a variety of engineered and natural processes for 55 frequently encountered TOrCs in treated wastewater, based on previously reported data and using existing predictive models. Correlations between physicochemical and biological properties of TOrCs and treatment performance were explored. Removal of TOrCs in all processes investigated in this study was found to be sensitive to matrix effects. Heuristic guidelines for selection of sequenced treatment processes for TOrCs management were established. A field reconnaissance of natural process of TOrCs was conducted by analyzing the occurrence and fate of a suite of TOrCs, as well as estrogenic activity in water and sediments in the Santa Cruz River, an effluent-dependent stream in Tucson, Arizona. Some TOrCs, including contributors to estrogenic activity, were rapidly attenuated with distance of travel in the river. TOrCs that have low biodegradability and low octanolwater partitioning coefficients were less removed. Results of independent experiments indicated potential indirect photodegradation of estrogenic compound by reactive species generated from photolysis of effluent organic matter. Utilizing advanced oxidation processes (AOPs) as tertiary water and wastewater treatment is an option to prevent discharge of TOrCs into the environment. Compared to conventional AOPs, the ability of generating hydroxyl radicals (•OH) without additional doses of hydrogen peroxide (H2O2) or ozone makes ultraviolet (UV) photolysis of ferric hydroxo complexes a novel AOP, especially in acidic environments. A Fe(III)/UV254 kinetic model, which combines Fenton-like mechanism, and photolyses of Fe3+, FeOH2+ and H2O2 was proposed and experimentally validated to predict Fenton-like and H2O2 direct UV254 photolysis scenarios, individually. Nevertheless, the model underestimated the ferrous ion development during Fe(III)/UV254 photolysis, perhaps due to the overprediction of the oxidation of Fe2+ by •OH. The UV/H2O2 AOP was also studied in this work. A predictive kinetic model was developed to evaluate process efficiency of oxidation of p-cresol by UV/H2O2 photolysis based on a complete reaction mechanism, including reactions of intermediates with •OH. Results of this study highlight the significance of consideration of radical scavenging effects by the byproducts from oxidation of organic matter in model prediction performance.
32

Sunlight Modulation for Optical Wireless Communication

Ammar, Sahar 04 1900 (has links)
Solar energy is widely used for electricity generation, heating systems, and indoor environment daytime illumination. Indeed, large amounts of Sunlight energy remain insufficiently used. In this work, we aim at employing sunlight for data transmission as another option for wireless communications. Being emitted by an uncontrollable source, taming the Sunlight is a challenging task that requires appropriate technolo- gies to manipulate incident light. Throughout this thesis, we first review switchable glass technologies and investigate their potential use for light modulation. Liquid Crystal Devices (LCD) have adequate response time and contrast characteristics for such an application. In this regard, we design a novel Dual-cell Liquid Crystal Shutter (DLS) by stacking two Liquid Crystal cells that operate in opposite manners, and we build our Sunlight modulator with an array of DLSs. Then, we adopt Time Division Multiplexing and polarization-based modulation to boost the data rate and eliminate the flickering effect. In addition, we provide mathematical modeling of the system and study its performance in terms of communication and energy consumption. Finally, we introduce some numerical results to examine the impact of multiple parameters on the system’s performance and compare it with state-of-the-art, which showed that our system features higher data rates and extended link ranges.
33

Crisis of Window. Lost Purpose of Daylight Opening

Milkeviciute, Agne January 2018 (has links)
This thesis concentrates on problematic field of architectural education and practice related to window role. Phenomena of window loosing it’s primary functional purpose [inside-outside connection in terms of view and daylight] and becoming more decorative element of the facade. This paper content consists of analysis of case studies by evaluating window provided light and view qualities using qualitative and quantitative methods in chosen office buildings. Analysis and results are followed by the discussion of window role oppositions between architect’s and user’s perspective together with secondary topics coming out of it. As the result of analysis and discussion - guidelines for window design are suggested and conclusive experiment of their customization is demonstrated. This thesis  concentrates on awareness of window identity crisis as well as examine and provide simple manners, which can increase quality of daylight and view through the openings in architectural planning.
34

DEVELOPMENT OF NOVEL SUSTAINABLE AND ENERGY EFFICIENT NANOTECHNOLOGY FOR WATER TREATMENT

Swarnakar, Prakash 01 May 2012 (has links)
No description available.
35

Modeling Radiation Transport in Biomimetic Configuration of Solar Cells for Enhanced Sunlight Capture Using the Monte Carlo Method

Verma, Navni 15 September 2014 (has links)
No description available.
36

Optimizing grape cluster exposure to increase desirable aroma compounds  and decrease disease severity

Liggieri, Silvia 07 February 2019 (has links)
By increasing fruit exposure to sunlight and influencing fruit development, leaf thinning in the fruit zone can improve grape quality and lower disease incidence; however, further investigations on the timing, varietal response and intensity are needed to optimize results and to better understand underlying physiologic responses. Fruit zone leaf thinning was applied at different timing and intensities to evaluate its effect on cluster health and fruit composition in Cabernet Sauvignon and Chardonnay. Treatments consisted of control (C), pre-bloom leaf thinning (PB) and two levels of fruit-set leaf thinning (three leaves, PF3 and six leaves, PF6). In an additional project on Cabernet Sauvignon, two levels of hedging (17th node, NH and 12th node, H) were integrated with no leaf thinning (L) and fruit set leaf thinning (LR, three leaves). All leaf thinning treatments consistently reduced disease incidence compared to control vines in both varieties, with the reduction extent varying between 2017 and 2018. Yield was not negatively affected by leaf thinning treatments, even though PB reduced cluster compactness by decreasing the number of berries per cluster of Chardonnay in 2017. Control vines tended to have greater titratable acidity than defoliated vines, while Brix and pH responses varied between seasons. No direct positive correlation was found between sunlight exposure and norisoprenoids concentration. Post fruit set leaf thinning PF6 consistently increase free norisoprenoids at harvest, while pre-bloom defoliation never did. Heterogeneous responses were observed for bound and total norisoprenoids. In Cabernet Sauvignon free, bound and total 1,1,6-trimethyl-1,2-dihydronaphtalene (TDN) was consistently increased by PF3. Hedging negatively influenced Brix and anthocyanins accumulation in 2017, and increased free norisoprenoids while decreasing the bound and total fraction. Results revealed that a high level of stress possiblt caused by excess sunlight and/or reduced photosynthesis might negatively affect norisoprenoids glycosylation. / Master of Science in Life Science / This project evaluates the effect of a grapevine canopy management practice on grape quality. The objective was to find a suitable technique to expose the fruits to sunlight in order to increase grape aroma concentration and improve grape sanitary status of Virginia vineyards. Leaves were removed from the fruit zone with different intensities at two grape developmental stages, in two varieties (Chardonnay and Cabernet Sauvignon). Treatments consisted of control, three leaves removed before blooming (PB) and three or six leaves removed after fruit set (PF3 and PF6 respectively) In an additional project with Cabernet Sauvignon, the effect of canopy height was integrated with the fruit zone defoliation. Results showed that the removal of leaves from the fruit zone is effective in improving grape sanitary status at harvest, with the improvement extent depending on the season climatic conditions and on the amount of leaves removed. Crop yield was not negatively affected by treatments. Non defoliated grapes tended to have greater acidity at harvest, while sugar responses were inconsistent. Aroma compounds responded heterogeneously to fruit zone defoliation, but volatile odorants were consistently greatest in the most exposed grapes (PF6) compared to all other treatments at harvest. Pre-bloom defoliation instead, never increased volatile aroma compounds compared to control at harvest. Generally, non-volatile odorants were greater in less severely defoliated vines or control. An overall positive effect was observed with PF3. Canopy height was demonstrated to be able to indirectly affect grape quality and composition, with the short canopy reducing grape’s sugar and color content and increasing grape’s volatile aroma compounds concentration at harvest in 2017. The removal of three or six leaves from the fruit zone in post fruit set could be a suitable practice to improve grape quality in the Virginia environment.
37

Virtuell ljussättning inom Augmented Reality : Semi-automatisk ljushantering för ökad upplevd realism / Virtual Lighting in Augmented Reality : A Semi-automatic approach for enhanced realism

Lundqvist, Oscar January 2018 (has links)
Denna studie avser att undersöka hur ökad upplevd realism kan uppnås i Augmented Reality (AR) applikationer, genom ökad användarinteraktion med utvalda, virtuella ljusparametrar. Den teoretiska referensramen omfattas av övergripande teorier kopplade till AR men även mer djupgående forskning kring virtuell ljussättning och ljusparametrar. I en domän där automatiserade lösningar för virtuell ljussättning dominerar, ämnar denna studie påvisa bristerna med automatisk hantering av virtuellt ljus och istället motivera en lösning av semi-automatisk karaktär. Studien avser även att söka svaret på vilken utav utvalda ljusparametrar som haft störst inverkan i åtagandet att öka upplevd realism. Med Action Design Research (ADR) som huvudsaklig forskningsmetod, utvecklas ett grundläggande tillägg till en befintlig AR applikation i nära samarbete med företaget Neava. Applikationstillägget möjliggör manuell justering av det virtuella ljusets riktning, intensitet och färgtemperatur. Applikationstillägget testas sedan av befintliga användare under observation, därefter besvarar användaren en enkät grundad i testet, där jämförelse mellan befintlig applikation och applikationstillägg är temat. Insamlade observations- och enkätdata sätts i centrum för analys med avsikt att förklara relevanta fenomen och mönster, kopplade till upplevd realism. Studien finner att det utvecklade applikationstillägget i 90% av fallen genererar en ökad upplevd realism. Vidare finner studien att den virtuella ljusparameter som bidragit mest till ökad realism är ljusriktning, efterföljt av ljusintensitet och den minst bidragande visar sig vara färgtemperatur. De slutsatser som dras i studien formuleras och presenteras avslutningsvis i form av en oberoende lista designprinciper. / The purpose of this study is to examine how an improved level of experienced realism could be achieved in Augmented Reality (AR) applications, by allowing increased user interaction with a chosen set of virtual lighting parameters. The theoretical foundation of this thesis is both concerned with surveys and literature reviews of AR in general but also virtual lighting and lighting parameters to a significant extent. In contrast to the majority of previous research, where estimating and managing virtual lighting is done automatically, this study suggests that a semi-automatic approach might be better suited in delivering improved levels of experienced realism. Through the course of this thesis it is also intended to evaluate which of the chosen lighting parameters that has had the greatest impact in achieving improved experienced realism. Action Design Research (ADR) is applied as the core research methodology and in collaboration with the company Neava, an addon for an existing AR application is developed. This addon enables manual adjustments of virtual light direction, intensity and color temperature. The addon is tested by users of the existing application under observation, afterwards the testers answer a brief survey concerning the test, where a comparison between existing application and addon is made. Data gathered from both the observations and the surveys are then subjects of an analysis, where different phenomena and findings regarding improved experienced realism is the focus. The study finds that roughly 90% of the testers did indeed experience an improved level of realism, using the semi-automatic addon. Furthermore the study finds that the virtual lighting parameter most effective in achieving this is light direction, followed by light intensity and least effective in the effort is color temperature. The conclusions made of this study are finally presented in the form of a list of design principles.
38

Making Time

Coffey, Christine 08 May 2008 (has links)
We are living in an age where the quantity of information has exceeded its quality. No doubt the digital and information revolutions have provided the world with countless positive improvements, but they have also increased the speed at which we live and work to the detriment of the heath of our world. This project explores ways in which designers can aid in an effort to slow down in order to reinvigorate a more sustainable graphic design product.
39

Sunlight Ancient and Modern: the Relative Energy Efficiency of Hydrogen from Coal and Current Biomass

Zhang, Ling 23 August 2004 (has links)
The significance of hydrogen production is increasing as fossil fuels are being depleted and energy security is of increasing importance to the United States. Furthermore, its production offers the potential to alleviate concerns regarding global warming and air pollution. In this thesis we focused on examining the efficiency of hydrogen production from current biomass compared to that from fossil fuel coal. We explored the efficiencies of maximum hydrogen production from biomass and from coal under current technology, namely coal gasification and biomass pyrolysis, together with following-up technologies such as steam reforming (SR). Bio-oil, product from pyrolysis and precursor for steam reforming, is hard to define. We proposed a simulation tool to estimate the pyrolytic bio-oil composition from various biomasses. The results helped us understand the accuracy that is needed for bio-oil composition prediction in the case it is converted to hydrogen. Hydrogen production is energy intensive. Therefore, heat integration is necessary to raise the overall thermodynamic efficiencies for both coal gasification and biomass pyrolysis. The results showed that considering the ultimate energy source, sunlight, about 6-fold more sunlight would be required for the coal to hydrogen than that for biomass to hydrogen. The main difference is in the efficiency of conversion of the ancient biomass to coal and therefore, for modern mankind, this loss has already been incurred.
40

Aproveitamento de radiação solar na geração de hidrogênio empregando fotocatalisadores do tipo CdS, ZnS e Cd (1-x)ZnxS

Lopes, Paula Aparecida Lima 07 1900 (has links)
Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2014-10-21T15:52:48Z No. of bitstreams: 1 Dissertação de mestrado Paula Lopes.pdf: 3114896 bytes, checksum: 64c14138aec1c0f19b0f9445d7a07625 (MD5) / Approved for entry into archive by Ana Hilda Fonseca (anahilda@ufba.br) on 2014-10-29T17:29:36Z (GMT) No. of bitstreams: 1 Dissertação de mestrado Paula Lopes.pdf: 3114896 bytes, checksum: 64c14138aec1c0f19b0f9445d7a07625 (MD5) / Made available in DSpace on 2014-10-29T17:29:36Z (GMT). No. of bitstreams: 1 Dissertação de mestrado Paula Lopes.pdf: 3114896 bytes, checksum: 64c14138aec1c0f19b0f9445d7a07625 (MD5) / Energia e Ambiente ocupam posições de destaque dentre os grandes desafios da hu manidade e a produção de hidrogênio a partir da reforma foto - induzida de solução aquosa de glicerol é uma investigação de grande interesse científico e importância para a sociedade e o meio ambiente , pelo fato de gerar energia limpa a partir de fontes reno váveis e com baixo custo. Neste sentido, o presente trabalho propõe desenvolver semicondutores do tipo sulfetos metálicos e soluções sólidas do tipo Cd (1 - x) Zn x S capazes de absorver luz visível e assim conduzir a reação de decomposição da água e glicerol le vando à produção de hidrogênio assistida por um simulador de luz solar . Para tanto, foi desenvolvido um método sonoquímico de síntese de nanopartículas dos sulfetos com diferentes proporções Cd:Zn:S nas soluções de partida. As análises de difração de raios X confirmaram a obtenção das fases dos sulfetos puros e soluções sólidas. As micrografias obtidas por microscopia eletrônica de varredura revelam diferentes morfologias a depender do teor de zinco nas soluções sólidas e a formação de nanoesferas de CdS pu ro em fase hexagonal. Os materiais ainda foram caracterizados por EDX, DRS e análise textural por adsorção de N 2 . A avaliação da atividade fotocatalítica na produção de hidrogênio revelou que todas as amostras contendo Cd em sua composição foram ativas, co m exceção da amostra S 8 ( Cd:S 1:8). O fotocatalisador que apresentou melhor atividade foi a solução sólida obtida com a proporção 1:8:4 (Cd:Zn:S), com uma taxa de produção de hidrogênio de 239  mol g - 1 h - 1 . Os resultados demonstraram que a introdução de zinco na matriz wurtzita de CdS aumenta a atividade fotocatalítica e a estab ilidade do fotocatalisador em me io aquoso. / Energy and Environment are ones of the great challenges of humanity and the production of hydrogen from photo - induced reforming of glycerol aqueous solution is an investigation of great scientific interest and importan t fo r the society and the environment . This process can generate clean e nergy from renewable sources with low cost. In this sense, the present work proposes to develop semiconductor s, metal sulfide type and solid solutions type, Cd (1 - x) Zn x S , able to absorb vis ible light and decompos e water and glycerol leading to hydrogen production assisted by a simulator sunlight. Thus , it was developed a sonochemical method to synthesi ze semiconductor nanopar ticles with different Cd:Zn:S ratios in starting solutions. X - ray d iffraction analysi s confirmed the formation of pure sulfides and solid solutions phase s . The micrographs obtained by scanning electron microscopy reveal different morphologies depending on the zinc content in the solid solutions and the formation of CdS na no - spheres in hexagonal pure phase. The material s w ere also ch aracterized by EDX, DRS and textural analysi s by N 2 adsorption . The assessment of photocatalytic activity in hydrogen production showed that all samples containing Cd were active with respect to hydrogen production , exception S 8 sample ( Cd:S 1:8). The photocatalyst that showed the best activity was the solid solution obtained with the ratio 1:8:4 (Cd:Zn:S), with a hydrogen production rate of 239 μmol g - 1 h - 1 . The results demonstrated that the int roduction of zinc in CdS wurtzite matrix increases the photocatalyt ic activity and stability of the photocatalyst in aqueous medium

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