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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.
81

Techno-Economic Feasibility and Life Cycle Assessment of Dairy Effluent to Biofuel via Hydrothermal Liquefaction

Summers, Hailey M. 01 May 2015 (has links)
Uncertainty in the global energy market and negative environmental impacts associated with fossil fuels has led to renewed interest in alternative fuels. The scalability of new technologies and production pathways are critically being evaluated through economic feasibility studies and environmental impact assessments. This work investigated the conversion of agricultural wast, delactosed whey permeate (delac), with yeast fermentation for the generation of biofuel via hydrothermal liquefaction (HTL). The feasibility of the process was demonstrated at laboratory scale with data leveraged to validate systems models used to perform industrial-scale economic and environmental impact analyses. Results showed a minimum fuel selling point of $4.56 per gasoline gallon equivalent (CGE), a net energy ratio (NER), defined as energy required to process biofuel divided by energy in the biofuel produced, of 0.81 and greenhouse gas (GHG) emissions of 30.03 g CO2-eq MJ-1. High Production costs can be attributed to operational temperatures of HTL while the high lipid yields of the yeast counter these heating demands, resulting in a favorable NER. The operating conditions of both fermentation and HTL contributed to the majority of GHG emissions. Further discussion focuses on optimization of the process, on the metrics of TEA and LCA and the evaluation of the process, on the metrics of TEA and LCA, and the evaluation of the process through a sensitivity analysis that highlights areas for directed research to improve commercial feasibility.
82

Examining the Impact of DIfferent Virtual Manipulative Types on the Nature of Students' SMall-Group Discussions: An Exploratory Mixed-Methods Case Study of Techno-Mathematical Discourse

Anderson-Pence, Katie L. 01 May 2014 (has links)
This study examined the influence of different virtual manipulative types on the nature of students’ techno-mathematical discourse (TMD) when working with a partner. The research used a concurrent mixed-methods design using identical samples to compare and synthesize the results. For this study, six fifth-grade students participated in nine sessions of mathematics instruction using virtual manipulatives. The study compared three virtual manipulative types: combined (multiple representations, open environment), pictorial (single visual representation, open environment), and tutorial (multiple representations, structured environment). Students’ levels of discourse in generalization, justification, and collaboration were measured as well as students’ use of physical and computer gestures while working with each virtual manipulative type. One-way ANOVAs indicated statistically significant differences in quality of student discourse when using the different virtual manipulative types. When working with combined virtual manipulatives, students’ discussions reflected consistently higher levels of discourse than when working with pictorial or tutorial virtual manipulatives. When working with tutorial and pictorial virtual manipulatives, students’ discussions reflected consistently lower levels of discourse. However, pictorial virtual manipulatives were associated with the largest amount of discussion among student pairs and the highest frequency of gesture use. The results of this study suggest that in order to encourage meaningful TMD, teachers should choose technology tools (e.g., virtual manipulatives) that combine multiple representations (i.e., combined virtual manipulative type) and provide the opportunity to engage in cognitively demanding tasks. The results of this study indicate that tutorial virtual manipulatives did not encourage meaningful mathematical discourse with these student pairs. This means that the tutorial virtual manipulative type may be better suited for the practice of mathematics concepts or for individual learning than for partner work. The patterns and trends identified in this study contribute to the existing literature on the complex issues that surround mathematical discourse and the use of technology in the classroom.
83

Techno-economic modelling of CO2 capture systems for Australian industrial sources.

Ho, Minh Trang Thi, Chemical Sciences & Engineering, Faculty of Engineering, UNSW January 2007 (has links)
Australia is recognising that carbon capture and storage (CCS) may be a feasible pathway for addressing increasing levels of CO2 emissions. This thesis presents a preliminary economic assessment and comparison of the capture costs for different Australian CO2 emission sources. The capture technologies evaluated include solvent absorption, pressure swing adsorption (PSA), gas separation membranes and low temperature separation. The capture cost estimated for hydrogen production, IGCC power plants and natural gas processing is less than A$30/tonne CO2 avoided. CO2 capture cost for iron production ranges from A$30 to A$40 per tonne CO2 avoided. Higher costs of A$40 to over A$80 per tonne CO2 avoided were estimated for flue gas streams from pulverised coal and NGCC power plants, oil refineries and cement facilities, and IDGCC synthesis gas. Based on 2004 and 2005 EU ETS carbon prices (A$30 to A$45 per tonne CO2 avoided), the cost of capture using current commercially available absorption technology may deter wide-scale implementation of CCS, in particular for combustion processes. A sensitivity analysis was undertaken to explore the opportunities for reducing costs. The high cost for capture using solvent absorption is dependent on the energy needed for solvent regeneration and the high capital costs. Cost reductions can be achieved by using new low regeneration energy solvents coupled with recycling the waste heat from the absorption process back to the steam cycle, and using low cost ???fit-for-purpose??? equipment. For membrane and PSA technologies, the capture costs are dominated by the flue gas and post-capture compressors. Operating the permeate or desorption stream under vacuum conditions provides significant cost reductions. Improvements in membrane and adsorbent characteristics such as the adsorbent loading or membrane permeability, CO2 selectivity, and lower prices for the membrane or adsorbent material provide further cost benefits. For low partial pressure CO2 streams, capture using low temperature ???anti-sublimation??? separation can be an alternative option. Low costs could be achieved by operating under low pressures and integrating with external sources of waste heat. Applying the cost reductions achievable with technology and process improvements reduces the capture and CCS costs to a level less than current carbon prices, making CCS an attractive mitigation option.
84

Process Synthesis and Optimization of Biorefinery Configurations

Pham, Viet 2011 August 1900 (has links)
The objective of this research was to develop novel and applicable methodologies to solve systematically problems along a roadmap of constructing a globally optimum biorefinery design. The roadmap consists of the following problems: (1) synthesis of conceptual biorefinery pathways from given feedstocks and products, (2) screening of the synthesized pathways to identify the most economic pathways, (3) development of a flexible biorefinery configuration, and (4) techno-economic analysis of a detailed biorefinery design. In the synthesis problem, a systems-based "forward-backward" approach was developed. It involves forward synthesis of biomass to possible intermediates and reverse synthesis starting with desired products and identifying necessary species and pathways leading to them. Then, two activities are performed to generate complete biorefinery pathways: matching (if one of the species synthesized in the forward step is also generated by the reverse step) or interception (a task is determined to take a forward-generated species with a reverse-generated species by identifying a known process or by using reaction pathway synthesis to link to two species.) In the screening problem, the Bellman's Principle of Optimality was applied to decompose the optimization problem into sub-problems in which an optimal policy of available technologies was determined for every conversion step. Subsequently, either a linear programming formulation or dynamic programming algorithm was used to determine the optimal pathways. In the configuration design problem, a new class of design problems with flexibility was proposed to build the most profitable plants that operate only when economic efficiency is favored. A new formulation approach with proposed constraints called disjunctive operation mode was also developed to solve the design problems. In the techno-economic analysis for a detailed design of biorefinery, the process producing hydrocarbon fuels from lignocellulose via the carboxylate platform was studied. This analysis employed many state-of-the-art chemical engineering fundamentals and used extensive sources of published data and advanced computing resources to yield reliable conclusions to the analysis. Case studies of alcohol-producing pathways from lignocellulosic biomass were discussed to demonstrate the merits of the proposed approaches in the former three problems. The process was extended to produce hydrocarbon fuels in the last problem.
85

Cyberqueer Techno-practices : Digital Space-Making and Networking among Swedish gay men

Tudor, Matilda January 2012 (has links)
Cyberqueer Techno-practices: Digital Space-Making and Networking by Swedish Gay Men     This study aims to highlight intersections of queer experiences and new media, by focusing on the use of digital platforms and communication practices among Swedish gay men. This is being carried out using a netnographic approach including an online survey and in-depth interviews among the target group, as well as field observations on gay catering online forums and GPS application software. Special attention is paid to the blur between online and offline, increasingly underpinned by innovations such as smartphones, tablet computers and GPS techniques, and how it may challenge and reconfigure concepts of public and private in relation to sexuality and sexual identity. Using a rich combination of queer theory and media and communication theory, the study intends to illuminate the underdeveloped potential of cross-fertilization between the fields. The concept of space has a central position, as the cyberqueer practices performed by gay men are argued to produce queer space that extends their social scope in a heteronormative environment. The interviews and the survey indicate that the use of digital media among gay men fulfill group specific purposes, for aspects such as social and sexual networking, as well as senses of community. Further, the possibility to visit digital spaces seems to have a particular significance during “coming-out processes”, since most of the informants have been dealing with their sexual identity and/or practice online, long before doing so offline. This is valid for individuals from both urban and rural areas, as the queer spaces online also are prioritized over offline alternatives when available.
86

Warring for Peace? : Swedish television’s take on war in a ‘post-documentary’ culture

Månsson, Cecilia January 2012 (has links)
While it has explained how power and knowledge directly imply one another, constructivist theories of international relations have shown how knowledge and language are extensively used for legitimizing war, conflict and intervention. It has further been shown how not only news media, but increasingly popular culture is powerful in creating meaning and establishing knowledge about war and conflict. At the same time, media scholars have shown that the development in television production is going towards a blur between information and entertainment, fact and fiction. This blur has been shown to often and effectively de-politicize ideological content. This study is a critical discourse analysis of the TV series Krig för fred (War for peace), broadcast on the Swedish public service television during the spring of 2011. The study has through answering questions in terms of genre and ideology, found that the material is an example of a blur between documentary and reality TV and that the material is exclusively from a Swedish point-of-view, yet presented through a discourse of claiming the real. One of the consequences of the mixed genre seemed to have been that as more space was given to individual characters and exoticising images of the Afghan landscape and people, less space was given to criticism, which made this representation of the war entertaining rather than informative to watch. While the only information given about Afghanistan in the TV series is that it is among the poorest countries in the world, more clues have been given as to how the Swedish military view themselves and have been represented in relation to ‘others’ in the world.
87

Re-problematizing The Contextualism-autonomy Debate In Architecture Within The Formal Logic Of Computational Operations

Okten, Deniz 01 January 2007 (has links) (PDF)
Technological innovations in the field of information and communication have transformed the nature of the spatial realm. The spatial realm has been engaged with the virtual realm, where a new approach has been mandatory for a possible and productive interrelation between the two. On the other hand, new technologies have affected architectural drafting, representation, construction and most significantly architectural design to generate remarkable conveniences and unnoticed interfaces for architects. New technologies offer a common arithmetical medium where a new augmented relationship between sciences and architectural design is enabled. All these transformations prepared the basis for a redefinition and reevaluation of the surrounding realm that is referred to as the context of architectural design. The recurrence of contextualist and de-contextualist debates and attitudes show that context is dealt with as a multi-layered concept in architecture. Within all above mentioned transformations, the issue of contextualism in architecture is reopened up where the definition of context is seen to be in a process of constant renovation, inheriting the complexities new technologies and design methods based on interdisciplinarity have brought. This thesis looks into this transformating status of the concept of context and argues for its productivity in architectural design.
88

Cooperation And Cluster Strategies Within And Between Technology- Intensive Organisations: How To Enhance Linkages Among Firms In The Techno-parks

Vucic, Irena 01 September 2009 (has links) (PDF)
Focus of this thesis will be on the network and cluster strategies within and between technology-intensive organizations/firms and how to manage those networks in order to improve their outcome in the context of building or enhancing innovative advances, technological capabilities and/or competitiveness. World today is characterized by rapid transformations in all aspects of human&rsquo / s life where innovation, technological change and technological progress play the most significant role. Therefore, technology-intensive organizations by engaging in strategic alliances, clusters and networks tend to extract maximum benefits i.e. to enable entry into the international markets and to develop core competences. Even though clusters have become a highly popular strategy, many of them fail to realize their intended goals. Thus, this thesis will attempt to explore why choosing a clustering strategy can be beneficial, as well as to provide better understanding of such cooperation and requirements for success. Main focus will be on investigating if there are inter-firm and firm-university linkages among the actors located in a particular techno-park, and to diagnose if the close proximity contributed and eased development of the networks among the firms settled in the METU Techno-park and Bilkent Cyber-park. Results of the analysis showed certain extent of firm-university relationships and low level of inter-firm interactions. This further implied necessity of the policy interventions for enhancement of those interactions if the studied techno-parks are to become successful in the sense of the theoretical techno-park model, and if the tenant firms are to extract maximum benefits associated with cluster concept in theory.
89

Club Texas : building community in electronic music fan culture through online collaboration / Building community in electronic music fan culture through online collaboration

Fancher, Robert A. 17 April 2013 (has links)
Club Texas: Building Community in Electronic Music Fan Culture through Online Collaboration is a report of results from a content analysis that analyzes the role of online participatory culture for community development and social capital for a local underground EDM ‘scene’ (Electronic Dance Music) in Dallas, TX. This study analyzes DallasDanceMusic.com (DDM), one of the first and largest message board communities to support the EDM community in Dallas, TX since 1994. The study measures participatory culture and social capital using content analysis of the site during high profile activity for a four-month period in 2012. / text
90

Τεχνοοικονομική μελέτη, διαστασιολόγηση και μελέτη υβριδικού Σ.Η.Ε. σε μόνιμη και μεταβατική κατάσταση στη νήσο Γαύδο

Βασιλειάδης, Χαράλαμπος 07 July 2015 (has links)
Η παρούσα διπλωματική εργασία πραγματεύεται την τεχνοοικονομική μελέτη ενός υβριδικού συστήματος στη νήσο Γαύδο, νότια του νομού Χανίων Κρήτης. Το συγκεκριμένο αντικείμενο της διπλωματικής επιλέχθηκε σε συνδυασμό με πρακτική άσκηση πάνω στο ίδιο θέμα στην εταιρεία ΔΕΗ Ανανεώσιμες. Στόχος της μελέτης είναι η διερεύνηση των εναλλακτικών λύσεων παραγωγής ηλεκτρικής ενέργειας στα μη διασυνδεδεμένα νησιά. Η ανάγκη αυτή προκύπτει από το εξαιρετικά υψηλό κόστος της παραγόμενης μεγαβατώρας σε νησιά όπως η Γαύδος. Με σκοπό την πλήρη ανάλυση του θέματος, αρχικά μελετώνται τα ιδιαίτερα τοπολογικά χαρακτηριστικά της Γαύδου και οι πιθανές θέσεις εγκατάστασεις του υβριδικού συστήματος βάσει μετρήσεων. Σημαντική παράμετρος της ανάλυσης αυτής είναι η κατά το δυνατόν μικρότερη επέμβαση στο οικοσύστημα του νησιού και ο σεβασμός της χλωρίδας και της πανίδας του. Στη συνέχεια, έχοντας καταλήξει στην δομή του προτεινόμενου συστήματος εξετάζονται συγκεκριμένες εμπορικές λύσεις με εκτενή έρευνα αγοράς. Η τελική επιλογή των προτεινόμενων προιόντων έγινε με βάση το χαμηλότερο κόστος και την υψηλότερη αξιοπιστία, διότι η συνεχής πρόσβαση στο νησί για συντήρηση του συστήματος δεν ενδείκνυται. Τo επόμενο βήμα της παρούσας μελέτης είναι διαστασιολόγηση του συστήματος, ώστε η λειτουργία του συστήματος να καλύπτει στο έπακρον το φορτίο σε μόνιμη και σε μεταβατική κατάσταση λειτουργίας. Οι βασικές μετρήσεις που απαιτούνται για αυτήν την μελέτη είναι χρονοσειρές αιολικού δυναμικού, ηλιακού δυναμικού και φορτίου. Το κομμάτι αυτό της διπλωματικής υλοποιήθηκε στο λογισμικό Homer. Το Homer προτείνει κάποια συστήματα που τεχνικά ικανοποιούν τις αρχικές προδιαγραφές του δικτύου και παράλληλα τα κατατάσσει με οικονομικούς κριτήρια. Για αυτό το λόγο, στην διπλωματική εργασία ακολουθεί οικονομική μελέτη των προτεινόμενων συστημάτων βάσει των όρων επένδυσης της αγοράς και του χρόνου απόσβεσης του επενδυμένου κεφαλαίου. Η οικονομική, λοιπόν, μελέτη οδηγεί στην πρόταση ενός τελικού υβριδικού συστήματος που καλύπτει τις ανάγκες του νησιού, σέβεται τα ιδιαίτερα χαρακτηριστικά του και είναι οικονομικά βιώσιμο ή μα συνάμα και κεδροφόρο. Στη συνέχεια το τελικό σύστημα εξετάζεται καθαρά από τεχνικής πλευράς σε μόνιμη και μεταβατική κατάσταση λειτουργίας. Πραγματοποιείται μελέτη ροής φορτίου και σφαλμάτων με τα λογισμικά του Power World και του Matlab συγκρίνοντας παράλληλα τα αποτελέσματά τους. Ιδίως το μοντέλο που κατασκευάστηκε στο Matlab, μπορεί να αποτελέσει ισχυρή βάση για την περαιτέρω μέλετη του συστήματος. Αξίζει να σημειωθεί, τέλος, ότι έχει καταβληθεί μεγάλη προσπάθεια ώστε η μελέτη και η προσομοίωση του συστήματος να ανταποκρίνονται με κάθε λεπτομέρεια στις ρεαλιστικές συνθήκες και τα χαρακτηριστικά του νησιού της Γαύδου και του υπάρχοντος συμβατικού σταθμού παραγωγής ενέργειας. / This thesis deals with the techno-economic study of a hybrid system on the island of Gavdos, south of Chania Crete. The object of this thesis was chosen in conjunction with practice on the same theme in the PPCR. The aim of the study is to explore the alternatives of electricity produced in the non-interconnected islands. This need arises from the extremely high costs of producing megawatts on islands like Gavdos. In order to fully analyze the issue, initially studied the particular topological features of Gavdos and possible installation locations of the hybrid system under measurement. An important aspect of this analysis is at least possible interference in the ecosystem of the island and the respect of flora and fauna. Then, having come to the structure of the proposed system are discussed specific trade solutions with extensive market research. The final selection of featured products was based on the lowest cost and highest reliability, because the continuous access to the island for maintenance of the system is not appropriate. To the next step of this study is sizing system, that operation of the system to cover the most of the load in permanent and transient operation. The basic measurements required for this study is time series wind power, solar and load capacity. This part of the thesis was implemented in software Homer. The Homer suggests some systems that meet the technical specifications of the original network while the ranks with economic criteria. For this reason, the thesis follows economic study of the proposed schemes under the terms of the investment market and the payback on invested capital. Economic therefore study leads to proposing a final hybrid system that meets the needs of the island, the particular features and is economically viable but also transcendent kedroforo. Then the final system considered purely from a technical standpoint in steady state and transient operation. Carry out a study load flow and fault with the Power World software and Matlab while comparing their results. Particular model was built in Matlab, can be a strong basis for further study of the system. It should be noted, finally, that has made ​​great efforts to study and simulation of the system to respond in detail to realistic conditions and characteristics of the island of Gavdos and the existing conventional power plant.

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