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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.
361

Conceptual design analysis of a collection and processing system for scrapped catalytic converters

Kuczka, Allan Anthony 20 January 2010 (has links)
<p>The systems engineering process has been applied to develop and evaluate a system that collects and processes scrapped catalytic converters to recover the platinum group metals retained by the converters' spent catalyst substrate.</p> <p> A needs analysis establishes a catalytic converter manufacturer's desire to reduce the cost of obtaining platinum group metals used to produce new catalytic converters. The analysis proposes a collection and processing system as an alternative to existing suppliers to provide these metals at a lower cost. The analysis applies the engineering process to develop the system's high-level requirements and devises its components, inter-relationships, and operation. This process establishes a system configuration used to evaluate the system's economic feasibility.</p> <p>The results of this analysis indicate that the collection and processing system is feasible within the constraints of available technology and economic resources.</p> / Master of Science
362

H-Seda: Partial Packet Recovery with Heterogeneous Block Sizes for Wireless Sensor Networks

Meer, Ammar M. 08 December 2012 (has links)
Wireless sensor networks (WSN) have been largely used in various applications due to its ease of deployment and scalability. The throughput of such networks, however, suffers from high bit error rates mainly because of medium characteristics. Maximizing bandwidth utilization while maintaining low frame error rate has been an interesting problem. Frame fragmentation into small blocks with dedicated error detection codes per block can reduce the unnecessary retransmission of the correctly received blocks. The optimal block size, however, varies based on the wireless channel conditions. In addition, blocks within a frame can have different optimal sizes based on the variations on interference patterns. This thesis studies two dynamic partial packet recovery approaches experimentally over several interference intensities with various transmission-power levels. It also proposes a dynamic data link layer protocol: Hybrid Seda (H-Seda). H-Seda effectively addresses the challenges associated with dynamic partitioning of blocks while taking the observed error patterns into consideration. The design of H-Seda is discussed in details and compared to other previous approaches, namely Seda+ and Seda. The implementation of H-Seda shows substantial enhancements over fixed-size partial packet recovery protocols, achieving up to 2.5x improvement in throughput when the channel condition is noisy, while delay experienced decreases to only 14 % of the delay observed in Seda. On average, it shows 35% gain in goodput across all channel conditions used in our experiments. This significant improvement is due to the selective nature of H-Seda which minimizes retransmission overhead by selecting the appropriate number of blocks in each data frame. Additionally, H-Seda successfully reduces block overhead by 50% through removing block number field reaching to better performance when channel conditions are identical.
363

The Role of Dissolved Organic Carbon and Preadaptation in the Biotransformation of Trace Organic Chemicals during Aquifer Recharge and Recovery

Ouf, Mohamed 05 1900 (has links)
Aquifer recharge and recovery (ARR) is a low-cost and environmentally-friendly treatment technology which uses conventionally treated wastewater effluent for groundwater recharge and subsequent recovery for agricultural, industrial or drinking water uses. This study investigated the effect of different dissolved organic carbon (DOC) composition in wastewater effluent on the fate of trace organic chemicals (TOrCs) during ARR. Four biologically active columns were setup receiving synthetic wastewater effluent with varying DOC compositions. The difference in DOC composition triggered variations in the microbial community’s diversity and hence its ability to degrade TOrCs. It was found that the presence of protein-like DOC enhances the removal of DOC in comparison with the presence of humic-like DOC. On the other hand, the presence of humic-like DOC, which is more difficult to degrade, improved the removal of several degradable TOrCs. Other column experiments were also carried out to investigate the role of previous and continuous exposure to TOrCs in their removal. The use of soil pre-exposed to low concentrations of TOrCs and DOC provided better removal of both DOC and TOrCs. The findings of this study suggest that the presence of more humic-like DOC in the effluent enhances the biotransformation of TOrCs during ARR. In addition, long exposure to both DOC and TOrCs increases the degree of their removal over time
364

Residential Microgrids for Disaster Recovery Operations

Hurtt, James William 07 January 2013 (has links)
The need for a continuous supply of electric power is vital to providing the basic services of modern life. The energy infrastructure that the vast majority of the world depends on, while very reliable, is also very vulnerable. This infrastructure is particularly vulnerable to disruptions caused by natural disasters. Interruptions of electric service can bring an end to virtually all the basic services that people are dependent on. Recent natural disasters have highlighted the vulnerabilities of large, economically developed, regions to disruptions to their supply of electricity. The widespread devastation from the 2011 Japanese Tsunami and Hurricane Irene in North America, have demonstrated both the vulnerability of the contemporary power grids to long term interruption of service and also the potential of microgrids to ride through these interruptions. Microgrids can be used before, during, and after a major natural disaster to supply electricity, after the main grid source has been interrupted. This thesis researches the potential of clean energy microgrids for disaster recovery. Also a model of a proposed residential microgrid for transient analysis is developed. As the world demands more energy at increasingly higher levels of reliability, the role of microgrids is expected to grow aggressively to meet these new requirements. This thesis will look at one potential application for a microgrid in a residential community for the purpose of operating in an independent island mode operation. / Master of Science
365

Places of memory: Experience manifest in post-war Sarajevo

January 2015 (has links)
Sarajevo is city as cultural palimpsest; its history shaped by the multiplicity of regimes and empires that have held the east-meets-west nexus. For years the various ethnicities and religions that comprised the city coexisted harmoniously, but the fall of the Yugoslavian federation in the late 1980s pushed Sarajevo into violent civil conflict. Sarajevo emerged from the war the capital of a new state, but was utterly decimated by the years of siege. In the intervening two decades, the city has superficially recovered: buildings have been rebuilt, infrastructures and institutions reestablished. A thriving black tourism economy has even taken root in the city - to many, a sign that the city has made peace with its fraught history. But violent protests against the government in the spring of 2014 belie this notion of peace; the city is still at odds with itself. Architecture cannot save the world, nor can it guarantee a path towards sustained peace. It can, however, serve as a form of reconciliation - a critical component of an urban healing process. Introducing interventions in phases will ensure smooth assimilation in an area likely wary of new systems, and might physically exemplify a healing process. Thoughtful architecture and urban planning can lay the foundation for healing and rejuvenating a city raw from conflict, but requires the strength of the community to support and nurture it. The designer's challenge is, in this case, particularly complex, and requires a conscientious and diplomatic approach, drawing from the local community itself. No one outside can guarantee that Muslims, Croats and Serbs in Bosnia can come together and stay together as free citizens in a united country sharing a common destiny, said President Clinton in 1995. / 0 / SPK / specialcollections@tulane.edu
366

Characterization, Analysis, and Optimization of Rotary Displacer Stirling Engines

Bagheri, Amirhossein 12 1900 (has links)
This work focuses on an innovative Rotary Displacer SE (RDSE) configuration for Stirling engines (SEs). RDSE features rotary displacers instead of reciprocating displacers (found in conventional SE configurations), as well as combined compression and expansion spaces. Guided by the research question "can RDSE as a novel configuration achieve a higher efficiency compared to conventional SE configurations at comparable operating conditions?", the goal of this study is to characterize, analyze, and optimize RDSE which is pursued in three technical stages. It is observed the RDSE prototype has an optimum phase angle of > 90° and thermal efficiency of 15.5% corresponding to 75.2% of the ideal (Carnot) efficiency at the source and sink temperatures of 98.6° C and 22.1° C, respectively. Initial results indicate that 125° phase angle provides more power than that of the theoretically optimum 90° phase angle. The results also show comparable B_n and significantly higher W_n values (0.047 and 0.465, respectively) compared to earlier studies, and suggest the RDSE could potentially be a competitive alternative to other SE configurations. Furthermore, due to lack of a regenerator, the non-ideal effects calculated in the analytical approach have insignificant impact (less than 0.03 kPa in 100 kPa). The clearance volume in the shuttled volume has a dramatic negative effect and reduces the performance up to 40%. Ultimately, utilizing CFD, it is proved that the existing geometry is relatively optimized where the optimum phase angle is 121° and geometric ratio D\/L for the displacer is 0.49.
367

Destinationsutveckling under politisk kris : En fallstudie om Tunisien 2011

Bergman, Sandra, Flauto, Mikaela January 2011 (has links)
The authors have during the spring semester 2011 studied the subject destination development during a political crisis, focusing on Tunisia. At the beginning of 2011 the country was in an uncertain political situation when the revolution of the Tunisian people occurred. This created massive demonstrations on the streets, and resulted in the current government's resignation. More effects of the revolution has been seen in a drastic decline of inbound tourists in the country, which in turn affected the country's population and economy. From this point on Tunisia as a destination needs to recover to once again become attractive to tourists. Further revolutions in neighboring countries such as Libya, have contributed to the tourists' reluctance to travel to Tunisia. From this point of view, the tourist operators stand in front of a challenge in how they best can highlight the destination, and the positive impacts the revolution has contributed with. The purpose of this paper is from a destination development perspective examine how organizations in Sweden work to regain tourists to Tunisia after a period of decline. To answer this purpose, the authors use of these following questions: How have the revolution of the people in the spring of 2011 affected the tourism industry in Tunisia? How do the various tourist operators in Sweden relate to the revolution of the people in Tunisia 2011? Could it be that this revolution in spite of demonstrations and unrest contributes to something positive for the tourism industry in Tunisia? The methodology used in this paper is qualitative in nature, where a number of respondents in Sweden were interviewed to seek answers to selected questions. A constructivist approach was applied in which reality is seen as constantly changing and is created by ongoing processes that change over time. Destination Development, image and recovery are the key concepts covered in the theoretical framework. Destinations may occur at various stages in its life cycle. This is to portray how a destination can evolve to stagnation and at worst die out. Tunisia is in a phase of decline after the revolution in which people are waiting for tourists to return to the country. The results of the survey show that the revolution in 2011 has affected the tourism industry in that it has contributed to a decline of inbound tourists. The country´s image has been affected and there is now a challenge for organizations in Sweden to improve this image to regain tourists from Sweden to Tunisia. The vision for Tunisia as a destination is that despite the great social changes create a stable and democratic society, and highlight the revolutionary message of a new, more open Tunisia, which in turn creates attractiveness for the tourism industry.
368

Hypotheses for Scratch Behavior of Polymer Systems that Recover

Bujard, Bernard 05 1900 (has links)
Scratch recovery is a desirable property of many polymer systems. The reason why some materials have demonstrated excellent scratch recovery while others do not has been a mystery. Explaining the scratch resistance based upon the hardness of a material or its crosslink density is incorrect. In this thesis, novel polymers were tested in an attempt to discover materials that show excellent scratch recovery - one of the most important parameters in determining the wear of a material. Several hypotheses were developed in an attempt to give an accurate picture of how the chemical structure of a polymer affects its scratch recovery. The results show that high scratch recovery is a complex phenomenon not solely dependent upon the presence of electronegative atoms such as fluorine.
369

Xenogenous Intrafallopian Transfer of Horse (Equus caballus) Gametes

Wirtu, Gemechu G. 27 August 1999 (has links)
This study was undertaken to evaluate fertilization and early embryo development of in vitro matured (IVM) horse oocytes following transfer with homologous sperm to the oviduct of estrous ewes. A total of 1023 follicles (5.1 per ovary) were found after processing 202 slaughterhouse ovaries by aspiration and subsequent slicing. Most follicles (79%) were less than 20-mm in diameter. Six hundred sixty-seven oocytes were recovered (3.3 per ovary; recovery rate, 65%). About two-thirds of oocytes were recovered by slicing, which yielded twice the number of oocytes as aspiration. Sixty four percent cumulus oocyte complexes (COCs) recovered by each method were grade A and the overall distribution of oocytes by grade was not affected by the method of recovery. Oocytes underwent IVM for an average of 41-h and were subjected to either in vitro fertilization (IVF) or xenogenous gamete intrafallopian transfer (XGIFT). At the onset of IVM, 83% COCs had compact cumulus investment. At the end of IVM, 78% COCs showed cumulus expansion. The expansion score was not improved with increasing the IVM duration from 32.3 to 50.3 h. Five (15%) IVF oocytes showed changes indicative of fertilization and two cleaved to 3 and 4-cell stages. Oviducts of 16 ewes were use for XGIFT, which involved surgical transfer of an average of 13 oocytes with 40x103 capacitated spermatozoa per oocyte. Of 259 oocytes transferred, 36 (14%) were recovered between 2 to 7 d post XGIFT and 13 (36%) showed cleavage ranging from the 2-cell to hatching blastocyst stage. The ovarian status of ewes and ligation of the uterotubal junction (UTJ) at the time of XGIFT, or the duration gametes were allowed to reside in the uterine tube, did not affect the recovery and cleavage rate. However, the most advanced stage embryos were recovered from ewes ovulating shortly after XGIFT. Fertilization following XGIFT was further demonstrated by the detection of ZFY loci in one embryo. This study demonstrated, for the first time, that horse embryos could be produced in a non-equine species. However, further studies focusing on the establishment of pregnancy in the mare using such embryos and improvement of the recovery and fertilization rates following XGIFT are recommended for use of XGIFT in horse assisted reproduction. / Master of Science
370

An Analysis of Post-Disaster Recovery Management in the 2016 and 2019 National Disaster Management Plans of India

Minville, Geneviève 13 April 2022 (has links)
This thesis analyzes how the Central Government of India (GoI) frames and justifies the post-disaster recovery phase in the recovery chapters of its 2016 and 2019 National Disaster Management Plans using Constructivist Grounded Theory and Textual Analysis. My analysis of the National Disaster Management Policy of 2009 demonstrates how disaster management mainly focuses on pre-disaster activities and how, as a result, recovery activities are less explored. I observed the same results in the National Plans, justifying the relevance of my thesis. The most significant findings of this research include: first, the GoI uses both Plans to detail decentralized efforts in recovery activities. Second, the GoI successfully puts the needs of communities at the heart of both Plans but fails to address communities as stakeholders and lacks consistency concerning the most vulnerable sections of the communities. Third, the GoI highlights psychological needs similarly in both Plans but does not acknowledge how psychological recovery is a long and ongoing process when explaining the recovery process. Lastly, it overly uses the “Build Back Better” (BBB) term but does provide details about concrete ways to achieve it. Drawing on the concepts of “disaster” and “recovery”, I argue that the GoI focuses on recovery based on hazards and fails to address the underlying causes of disasters in the recovery chapters of its Plans. Moreover, I argue that it successfully harmonizes with the dominant discourse of the international community but uses some institutional concepts such as BBB as buzzwords. Finally, I argue that the Plans reflect the priorities of the Government and that the 2019 Plan is not more inclusive as it aspires to be.

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