A Practical Cooperative Multicell MIMO-OFDMA Network Based on Rank Coordination

An important challenge of wireless networks is to boost the cell edge performance and enable multi-stream transmissions to cell edge users. Interference mitigation techniques relying on multiple antennas and coordination among cells are nowadays heavily studied in the literature. Typical strategies in OFDMA networks include coordinated scheduling, beamforming and power control. In this paper, we propose a novel and practical type of coordination for OFDMA downlink networks relying on multiple antennas at the transmitter and the receiver. The transmission ranks, i.e.\ the number of transmitted streams, and the user scheduling in all cells are jointly optimized in order to maximize a network utility function accounting for fairness among users. A distributed coordinated scheduler motivated by an interference pricing mechanism and relying on a master-slave architecture is introduced. The proposed scheme is operated based on the user report of a recommended rank for the interfering cells accounting for the receiver interference suppression capability. It incurs a very low feedback and backhaul overhead and enables efficient link adaptation. It is moreover robust to channel measurement errors and applicable to both open-loop and closed-loop MIMO operations. A 20% cell edge performance gain over uncoordinated LTE-A system is shown through system level simulations.Comment: IEEE Transactions or Wireless Communications, Accepted for Publicatio

Personal excavation: multiplicity and museological display

Modern and contemporary artists have employed and co-opted the technologies of industrial mass production to create and distribute works of art in forms variously termed as multiples, printed matter or mail art. This strategy was pre-eminent in the 1960s and early 1970s when there was a widespread interest among artists in creating prints and books as works of art, and it was most central to the art group known as Fluxus, in Conceptual art and in the mail art movement. The multiple has re-emerged in recent contemporary art and it is an important strand in my practice. However, my works are not only informed by the methods of industrial mass-production, but also by the practices of the hand-made. It is one of my prime principles to engage with the theme of multiplicity and to use multiply produced forms. The potentialities by assembled or collaged image provides a very remarkable point from which to approach contemporary aesthetic debates within postmodernism and to launch any searching examination of the formative currents in post-modern art. While contemporary art has challenged the rigid boundaries between form and content, the role of ‘the museological display’ remains crucial to the understanding of complex and uncanny elements in contemporary art practices. In my opinion, the condition of being on display is, therefore, fundamental to the construction of the category of ‘Art’ in the western world. An interrogation of the museum artefact has been one of my longstanding projects since 1992. In my work, I have struggled to explore aspects of visual potentiality through five years’ research in London. In summery, my research is approached in the following ways: First, I engaged with notion of ‘pseudo-archaism’ approached through my knowledge of ancient Korean artefacts and culture and use this as a way of re-questioning the western museum artefact. In my view, western museum practices employ a mode of archaeological methodology that can be understood as a form of personal excavation. Thus exploiting my position as a Korean national moved to London, my work engages with issues linked to the hybrid and cultural displacement and tied to the process of migration. Second, I analyse the nature of the artists’ inherent collecting impulse both through my personal collecting and by reference to the collecting practices of other contemporary artists. Consequently, my research carries me into the areas of psychoanalysis and sociology. Third, I analyse the appropriateness of the museological display as medium. In my investigation, I propose that the museum artefact when displayed in multiple forms can be approached by the use of an Eastern-informed meditative conception and quasi-scientific archaeological method. Lastly, I try to conceptualise my use of found materials. Throughout my research, I try to evaluate and conceptualise crucial elements of my practice such as ambiguity, authenticity, repetition, and consistency. The methodology that informs my practice is tied to researching the museum artefact in relation to my cultural identity. In this way, I have considered questions of personal identity and taxonomical methodology, and have approached identity as both ambiguous when in the process of migration and simultaneously linked to my experience of cultural displacement. 6 These are crucial parameters within which to find and develop my own visual language. As my work has progressed, I have had to establish the principles that inform my project as a sort of archaeological process: namely, one involving collecting, classification and display. At the same time, I am always aware of the hand-made aspects of artefacts. This is because I am instinctively interested in both their physical presence, and their symbolic aspect, which generates psychoanalytical associations, especially ideas of repetition and multiplicity. It is in my research into materials, particularly bones and stones, that my acts of personal collecting can be seen as a form of personal discovery and excavation. Throughout my work, I always keep in my mind the sense that subjectivity has to be objective and objectivity has to be subjective. In Chapter 1, I debate the view that instinctive collecting impulses in artists in relation to the assemblages of various found materials might be understood in terms of ‘hunting’ and the notion of art objects as ‘hunting objects’. My position exploits the repetitive nature of personal collecting as a form of personal excavation, which is associated in my own imagination, in terms of hunted objects. My works have also been careful to develop the innate possibilities and potentialities of the materials themselves. Thus, I try to link the collecting principles and motivations of both western and eastern museum artefact. In my research, I regard my experiences in London as an important source to consider hybrid and cultural displacement in post-modernity. In my examination of the dialogue between the artist and archaeology, I link my interest in pseudo-archaism to the concept of spontaneous response taken from Korean aesthetics

Effect of hydrostatic pressure on anelastic stress relaxation in a mixed-alkali silicate glass

The effect of hydrostatic pressure on the anelastic stress relaxation of a mixed-alkali silicate glass (0.05 Na₂O, 0.95 K₂O, 3 SiO₂) was studied at 75°C between ambient pressure and 6 kbar. The activation volume of diffusion was found to be - 4.2 cm³/mole. It is proposed that a reequilibration of the defect population at pressure gives rise to the negative activation volume of diffusion --Abstract, page ii

Customizing an English-Korean Machine Translation System for Patent Translation

PACLIC 21 / Seoul National University, Seoul, Korea / November 1-3, 200

Incorporating Statistical Information of Lexical Dependency into a Rule-Based Parser

PACLIC 23 / City University of Hong Kong / 3-5 December 200

Development of Nanocomposite Powders for the SLS Process to Enhance Mechanical Properties

In an effort to fabricate prototypes with improved mechanical properties in the dual laser sintering process, functionalized graphite nanoplatelets were added to the PA-12 powder to produce a nanocomposite powder. The PA-12 powder was chosen as the matrix polymer because it has features conducive to laser sintering such as relatively low melting temperature and high mechanical properties. The GNPs were oxidized through a nitric acid treatment to improve the interfacial bonding. The resulting nanocomposite powder was layered and sintered by laser without any sign of agglomeration. Although the result is preliminary, it nevertheless shows the suitability of the nanocomposite powder for the laser sintering process.Mechanical Engineerin