In a counter-current two-phase flow system, flooding can be defined as the onset of flow reversal of the liquid component which results in an upward co-current flow. Flooding in the surge line of pressurized water reactors poses a significant technical challenge in the analysis of several postulated nuclear reactor accident scenarios. Despite the importance of flooding in these analyses, previous work does not identify a universally accepted rigorous physics-based model of flooding, even for the simple case of flooding in adiabatic, vertical tubes. This can be attributed to a lack of conclusive understanding of the physics of two-phase counter-current flow, specifically the mechanism of flooding, and the large amount of uncertainty among data from various flooding experiments. This deficiency in phenomenological and experimental knowledge has led to the use of many empirical and semi-empirical correlations for specific system conditions and geometries. The goal of this work is the development of a model for flooding in vertical, adiabatic tubes from first principles. To address a source of uncertainty in the analysis of flooding, a model for the prediction of average film thickness in annular co- and counter-current flows has been developed by considering the conservation of momentum of the liquid and gas flows. This model is shown to be a quantitative improvement over the most commonly used models, those of Nusselt and Belkin, Macleod, Monrad, and Rothfus. The new model better considers the effects of interfacial shear and tube curvature by using closure relations known to represent forces appropriately in co- and counter-current flow. Previous work based on semi-empirical flooding models has been analyzed to develop a new theory on the hydrodynamic mechanism which causes flooding. It is postulated that the growth of an interfacial wave due to interfacial instability results in a flow reversal to ensure that momentum is conserved in the counter-current flow system by causing a partial or complete co-current flow. A model for the stability of interfacial waves in a counter-current flow system is proposed and has been developed herein. This model accurately represents the geometric and flow conditions in vertical adiabatic tubes and has been shown to have limits that are consistent with the physical basis of the system. The theory of waves of finite amplitude was employed to provide closure to an unknown parameter in the new model, the wave number of the wave that generates the interfacial instabil- ity. While this model underpredicts the flooding superficial gas velocity, the result is a conservative estimate of what conditions will generate flooding for a system. In the context of the analysis of a nuclear reactor, specifically a pressurized water reactor, conservatism means that the gas flow rate predicted to cause flooding for a fixed liquid flow rate will be less than the flow rate found experimentally, mean- ing that liquid delivery to the core would be safely underestimated. Future work includes the improvement of the closure relation for the limiting wave number that will cause unstable interfacial waves, as well as an assessment of the applicability of the stability-based model to flooding in the presence of phase change and flooding in complex geometries.

The purpose of this study was to determine how well the Monte Carlo transport code FLUKA can simulate a tissue-equivalent proportional counter (TEPC) and produce the expected delta ray events when exposed to high energy heavy ions (HZE) like in the galactic cosmic ray (GCR) environment. Accurate transport codes are desirable because of the high cost of beam time, the inability to measure the mixed field GCR on the ground and the flexibility they offer in the engineering and design process. A spherical TEPC simulating a 1 um site size was constructed in FLUKA and its response was compared to experimental data for an 56Fe beam at 360 MeV/nucleon. The response of several narrow beams at different impact parameters were used to explain the features of the response of the same detector exposed to a uniform field of radiation. Additionally, an investigation was made into the effect of the wall thickness on the response of the TEPC and the range of delta rays in the tissue-equivalent (TE) wall material. A full impact parameter test (from IP = 0 to IP = detector radius) was performed to show that FLUKA produces the expected wall effect. That is, energy deposition in the gas volume can occur even when the primary beam does not pass through the gas volume. A final comparison to experimental data was made for the simulated TEPC exposed to various broad beams in the energy range of 200 - 1000 MeV/nucleon. FLUKA overestimated energy deposition in the gas volume in all cases. The FLUKA results differed from the experimental data by an average of 25.2 % for yF and 12.4 % for yD. It is suggested that this difference can be reduced by adjusting the FLUKA default ionization potential and density correction factors.

Thesis (M.B.A.)--University of North Carolina Wilmington, 2009. / Title from PDF title page (February 17, 2010) Includes bibliographical references (p. 21)

Thesis (Ph. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 167-172). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 167-172). Also available on the Internet.

At present the literature of counter-monument studies does not account for the complex interactions of irony and nostalgia in memorial spaces. The three case studies examined in this project show that nostalgia can produce critically engaging spaces of deliberation depending on how ironic commemoration intervenes in comic or tragic frames. In order to show that more rhetorical focus is possible, I have challenged the conceptualization of counter-monument studies through what I have termed the “ironic monumental disruption.” Monument studies must address how the idea of the counter-monument, in which the "counter" supposedly resides in the artifact itself, valorizes monolithic critiques and fails to recognize that contexts, interactions, and artifacts all shape the symbolism of the commemorative site. Alternatively, ironic monumental disruptions offer critical and deliberative opportunities in their interactions with visitors and provide more conceptual insight into transitional commemorative practices. The monuments reviewed in this project initially appeared to provide additional reinforcement for escapist, capitalist narratives, but my examination of them has revealed that allowing for (ironic) commemorative contradictions provides discursive openings for publics unknowingly silenced by a lack of public deliberation. Commemorative irony produces valuable insights into the current historical moment and the representational issues created by ideological transitions. The citizens of Bosnia, Bulgaria, and Hungary express varying levels of nostalgia about their communist past, which is why the commemorative sites within these countries create a valuable spectrum of ironic and nostalgic entanglements. Commemorative irony produces valuable insights into the current historical moment and the representational issues created by ideological transitions. / text

The consumption of LSD and similar psychedelic drugs in New York City led to a great deal of cultural innovations that formed a unique psychedelic subculture from the early 1960s onwards. Historians and other commentators have offered conflicting views on this phenomenon by using either an epidemiological approach or by giving drug users more agency. The present study sides with the latter category to offer a new social history of LSD, but problematizes this topic in a sophisticated way by understanding psychedelic drug use as a social fact that in turn produces meaning for its consumers. It analyses the multiple cultural features of psychedelia through the lenses of politics, science, religion, and art, but also looks at the utopian and radical off-shoots of that subculture. To balance this thematic approach, it historicises the subculture by analysing its early days and discussing its origins, and then by pointing to the factors that led to its metamorphosis towards the end of the 1960s. In order to give LSD consumers a clearer voice, this dissertation is based on memoirs, correspondence and interviews that are used to balance press coverage gleaned from archival collections. With this wide array of primary sources supplemented by up-to-date secondary literature, it argues that the use of LSD and psychedelics led to a rich subculture that can be explained by the inherent complexity of the psychedelic experience. In turn, the plurality of opinions regarding the meaning and purposes of the experience led to tensions and polarisations within the large subculture, as well as with other drug subcultures and outsiders leery of illicit drug use. In doing so, this dissertation contributes to the social history of illicit substance consumption and adds to the fields of urban history and the history of subcultures, and makes a case for understanding LSD and psychedelics as a unique category of forbidden drugs that differ vastly in their cultural meaning from other drugs.

Η παρούσα διπλωματική προτείνει μια hardware υλοποίηση του μηχανισμού πιστοποίησης μηνυμάτων βασισμένη στο πρότυπο Galois/Counter Mode (GCM) . O αλγόριθμος κρυπτογράφησης Galois/Counter Mode (GCM) εκδόθηκε από τον οργανισμό National Institute of Standards and Technology (NIST) τον Νοέμβριο του 2007. Σε συνεργασία με τον μηχανισμός κρυπτογράφησης μηνυμάτων, υλοποιείται το πρότυπο GCM για online λειτουργία. Στο Κεφάλαιο 1, αρχικά γίνεται μια σύντομη ιστορική αναδρομή στον τομέα της κρυπτογραφίας. Στην συνέχεια παρουσιάζονται οι λόγοι που οδήγησαν στην δημιουργία αυτού του αλγορίθμου. Ακολουθεί μια σύντομη εισαγωγή στον GCM και στους τρόπους με τους οποίος αυτός δουλεύει. Στο τέλος του κεφαλαίου αναφέρονται οι πρακτικές εφαρμογές που έχει η χρήση του GCM. Στο Κεφάλαιο 2, αρχικά αναφέρονται οι συμβολισμοί που χρησιμοποιούνται στην διπλωματική καθώς και οι βασικές έννοιες που χρησιμοποιούνται. Στην συνέχεια, αναλύεται το μαθηματικό υπόβαθρο που είναι απαραίτητο για την κατανόηση των εσωτερικών μηχανισμών του GCM. Η ανάλυση που γίνεται σε αυτή την ενότητα αποτελεί και την βασική αρχή στην οποία στηρίχτηκε η δημιουργία του αλγορίθμου. Ακολουθεί η ανάλυση των μαθηματικών συνιστωσών του GCM. Η ενότητα αυτή κατατάσσεται τόσο σε μαθηματική ανάλυση όσο και σε hardware προσέγγιση των επιμέρους συνιστωσών . Ιδιαίτερο ενδιαφέρον παρουσιάζει η τελευταία υποενότητα του κεφαλαίου που παρουσιάζει τον τρόπο με τον οποίο από τον σειριακό πολλαπλασιαστή στο GF(2128) οδηγούμαστε στον παράλληλο πολλαπλασιαστή. Στο Κεφάλαιο 3, αρχικά παρουσιάζεται ο Advanced Encryption Standard (AES) και πιο συγκεκριμένα η forward function αυτού με υποστηριζόμενο κλειδί 128 bit. Στην συνέχεια του κεφαλαίου, παρουσιάζονται τα πλεονεκτήματα για την υλοποίηση με χρήση FPGAs, επίσης γίνεται μια σύντομη περιγραφή των βασικών διαφορών που παρουσιάζονται στις δύο οικογένειες FPGAs που χρησιμοποιήθηκαν. Στο Κεφάλαιο 4 , πραγματοποιείται η ανάλυση του αλγορίθμου GCM βασισμένη στο recommendation του NIST. Παρουσιάζονται όλοι οι επιμέρους αλγόριθμοι που χρησιμοποιούνται καθώς και ο τρόπος με τον οποίον αυτοί αλληλεπιδρούν και συνεργάζονται για την δημιουργία του GCM αλγορίθμου. Στο τέλος του κεφαλαίου, αναφέρονται οι απαιτήσεις για key και IV που πρέπει να ικανοποιούνται για να θεωρείται ο αλγόριθμος κρυπτογραφικά ισχυρός. Στο Κεφάλαιο 5, αρχικά γίνεται μια top down ανάλυση του GCM. Η ανάλυση αυτή χρησιμοποιείται στην δεύτερη ενότητα όπου προτείνεται και αναλύεται η αρχιτεκτονική που χρησιμοποιήθηκε για την hardware υλοποίηση. Στην συνέχεια, αναλύονται τα βασικά δομικά στοιχεία του GCM. Στην τελευταία ενότητα αναφέρεται η δομή που χρησιμοποιήθηκε με σκοπό την υλοποίηση για high speed απαιτήσεις. Στο Κεφάλαιο 6, αρχικά γίνεται εισαγωγή στον μηχανισμό πιστοποίησης μηνυμάτων έτσι όπως αυτό υλοποιήθηκε. Στην συνέχεια , παραθέτονται τα αποτέλεσμα που προέκυψαν από την εξομοίωση του VHDL κώδικα. Ακολουθούν τα αποτελέσματα της σύνθεσης και σύγκριση μεταξύ διαφορετικών τρόπων υλοποίησης. Στο τέλος του κεφαλαίου γίνεται σύγκριση μεταξύ των δύο τεχνολογιών που χρησιμοποιήθηκαν για την σύνθεση. Στο κεφάλαιο 7, αρχικά γίνεται εισαγωγή στον τρόπο με τον οποίο ο μηχανισμός πιστοποίησης και κρυπτογράφησης μηνυμάτων συνεργάζονται. Στην δεύτερη ενότητα παραθέτεται ο τρόπος λειτουργίας του GCM μηχανισμού που υλοποιήθηκε. Ακολουθούν τα αποτελέσματα της εξομοίωσης. Στην τελευταία ενότητα παραθέτονται τα αποτέλεσμα σύνθεσης σε δύο διαφορετικές τεχνολογίες. Στο Παράρτημα Α παρουσιάζεται ο τρόπος χρήσης του Xilinx ISE που χρησιμοποιήθηκε για την σύνθεση του VHDL κώδικα για την τεχνολογία Virtex 5. Τέλος στο Παράρτημα Β παρουσιάζονται κάποια βασικά κομμάτια του κώδικα C. / The Galois/Counter Mode of Operation (GCM), recently standardized by NIST, simultaneously authenticates and encrypts data at speeds not previously possible for both software and hardware implementations. In GCM, data integrity is achieved by chaining Galois field multiplication operations while a symmetric key block cipher such as the Advanced Encryption Standard (AES), is used to meet goals of confidentiality.

Beyond possible sovereignty disputes resulting from melting Arctic ice, very little is said or written about the maritime security implications of climate change. What does climate change mean for Canadian maritime security, and how can Canada adequately prepare to ensure continued safe and secure use of the world’s oceans in an era of climate change? Climate change is relevant to maritime security through two chief dimensions. First, navies will more frequently be tasked to deliver humanitarian assistance and disaster relief in the wake of more intense natural disasters. Second, increasing disorder on land will ‘slop over’ into the world’s oceans, threatening the safety of maritime commerce. Canada has stakes in both of these dimensions, and so there is great impetus for preparedness. The recommended model for preparedness sees Canada’s navy adopting a more varied fleet structure, one better suited for constabulary and diplomatic functions as opposed to traditional military functions.

Both security and human rights are important to all within the civilized world. Yet there are some serious tensions between the two political norms. For instance, it may not be easy for a state or the international community to reconcile well intentioned acts to maintain security and to preserve human rights. In the recent past, such a difficulty has been played out not only in the events, but also in the aftermath of the September 11, 2001 terrorist attacks in the United States. The result of the attacks, culminating in the massive loss of lives and property, has been in the adoption of various international treaties and domestic laws that have swiftly been enacted and deployed to counter terrorism, and the development of a concept of a state of “urgency” that appears to shadow the obligation to protect fundamental human rights, particularly the right to life under international law. This thesis thus focuses on the promotion and protection of fundamental human rights, particularly, the right to life with the subsequent declaration of the “war on terror” by the United States. The work targets the debate between security and human rights in the light of terrorism post 9/11, highlights the impact of choosing one ideal over another, and eventually rationing out a balance that would serve as a threshold for upholding standards in both security and human rights in the face of terrorism threats. Essentially, however, this thesis is hinged on the argument that to allow the ideal of security which apparently appears advantageous to a “continuing state of urgency” to overwhelmingly influence the implementation of counter-terrorism measures while paying no attention to the fundamental right to life would constitute a paradox in combating terrorism. I posit that the result of the above exercise, if chosen, implies more tragic consequences when implemented than the singular acts of terrorism in themselves. / Thesis (Master, Law) -- Queen's University, 2011-10-03 13:40:21.534