High efficiency fiber to waveguide optical coupler in silicon-on-insulator-based slot waveguides - art. no. 68310R

We propose a novel optical fiber-to-waveguide coupler for integrated optical circuits. The proper materials and structural parameters of the coupler, which is based on a slot waveguide, are carefully analyzed using a full-vectorial three dimensional mode solver. Because the effective refractive index of the mode in a silicon-on-insulator-based slot waveguide can be extremely close to that of the fiber, a highly efficient fiber-to-waveguide coupling application can be realized. For a TE-like mode, the calculated minimum mismatch loss is about 1.8dB at 1550nm, and the mode conversion loss can be less than 0.5dB. The discussion of the present state-of-the-art is also involved. The proposed coupler can be used in chip-to-chip communication.

Native deep level defects in ZnO single crystal grown by CVT method - art. no. 68410I

Hall effect, photoluminescence (PL), infrared absorption, deep level transient spectroscopy (DLTS), and Raman scattering have been used to study property and defects of ZnO single crystal grown by a chemical vapor transport method (CVT). As-grown ZnO is N type with free electron density Of 10(16)-10(17)cm(-3). It has a slight increase after 900 degrees C annealing in oxygen ambient. The DLTS measurement revealed four deep level defects with energy at 0.30eV, 0.50eV, 0.68eV and 0.90eV in the as-grown ZnO sample, respectively. After the high temperature annealing, only the 0.5eV defect survive and has a concentration increase. PL results of the as-grown and annealed ZnO indicate that the well-known green emission disappear after the annealing. The result suggests a correlation between the 0.68eV defect and the green PL peak. Results of P-doped ZnO were also compared with the undoped ZnO sample. The nature of the defects and their influence on the material property have been discussed.

Plasma induced damage in GaN-based light emitting diodes - art. no. 68410X

The effects of plasma induced damage in different conditions of ICP and PECVD processes on LEDs were presented. For ICP mesa etch, in an effort to confirm the effects of dry etch damage on the optical properties of p-type GaN, a photoluminescence (PL) measurement was investigated with different rf chuck power. It was founded the PL intensity of the peak decreased with increasing DC bias and the intensity of sample etched at a higher DC bias of -400V is less by two orders of magnitude than that of the as-grown sample. Meanwhile, In the IN curve for the etched samples with different DC biases, the reverse leakage current of higher DC bias sample was obviously degraded than the lower one. In addition, plasma induced damage was also inevitable during the deposition of etch masks and surface passivation films by PECVD. The PL intensity of samples deposited with different powers sharply decreased when the power was excessive. The PL spectra of samples deposited under the fixed condition with the different processing time were measured, indicating the intensity of sample deposited with a lower power did not obviously vary after a long time deposition. A two-layer film was made in order to improve the compactness of sparse dielectric film deposited with a lower power.

Ground target detection, classification and sensor fusion in distributed fiber seismic sensor network - art. no. 683015

This paper describes the ground target detection, classification and sensor fusion problems in distributed fiber seismic sensor network. Compared with conventional piezoelectric seismic sensor used in UGS, fiber optic sensor has advantages of high sensitivity and resistance to electromagnetic disturbance. We have developed a fiber seismic sensor network for target detection and classification. However, ground target recognition based on seismic sensor is a very challenging problem because of the non-stationary characteristic of seismic signal and complicated real life application environment. To solve these difficulties, we study robust feature extraction and classification algorithms adapted to fiber sensor network. An united multi-feature (UMF) method is used. An adaptive threshold detection algorithm is proposed to minimize the false alarm rate. Three kinds of targets comprise personnel, wheeled vehicle and tracked vehicle are concerned in the system. The classification simulation result shows that the SVM classifier outperforms the GMM and BPNN. The sensor fusion method based on D-S evidence theory is discussed to fully utilize information of fiber sensor array and improve overall performance of the system. A field experiment is organized to test the performance of fiber sensor network and gather real signal of targets for classification testing.

Wavelength-selectable DFB laser with wide gain bandwidth realized in nonidentical quantum well - art. no. 60200W

Width varied quantum wells show a more flat and wide gain spectrume (about 115nm) than that of identical miltiple quantum well. A new fabricating method was demonstrated in this paper to realize two different Bragg grating in an selectable DFB laser based on this material grown identical chip using traditional holographic exposure. A wavelength by MOVPE was presented. Two stable distinct single longitudinal mode of 1510nm and 1530nm with SMSR of 45 dB were realized.

Leakage current analysis in AlGaInP/GaInP multi-quantum well lasers by the electrical derivative method - art. no. 60202F

In AlGaInP/GaInP multi-quantum well (MQW) lasers, the electron leakage current is a much more serious problem than that in laser diodes with longer wavelength. To further improve the output performance, the leakage current should be analyzed. In this letter, the temperature dependence of electrical derivative characteristics in AlGaInP/GaInP multi-quantum well lasers was measured, and the potential barrier for electron leakage was obtained. With the help of secondary ion mass spectroscopy (SIMS) measurement, theoretical analysis of the potential barrier was presented and compared with the measurement result. The influence of p-cladding doping level and doping profile on the potential barrier was discussed, and this can be helpful in metalorganic chemical vapor deposition (MOCVD) growth.

Nonradiative recombination effect on photoluminescence decay dynamics in GaInNAs/GaAs quantum wells - art. no. 61180Z

The nonradiative recombination effect on the photoluminescence (PL) decay dynamics in GaInNAs/GaAs quantum wells is studied by photoluminescence and time-resolved photoluminescence under various excitation intensities and temperatures. It is found that the PL decay dynamics strongly depends on the excitation intensity. In particular, under the moderate excitation levels the PL decay curves exhibit unusual non-exponential behavior and show a convex shape. By introducing a new concept of the effective concentration of nonradiative recombination centers into a rate equation, the observed results are well simulated. In the cw PL measurement, a rapid PL quenching is observed even at very low temperature and is of the excitation power dependence. These results further demonstrate that the non-radiative recombination process plays a very important role on the optical properties of GaInNAs/GaAs quantum wells.

From Art to Avant Garde? Television, Formalism and the Arts Documentary in 1960's Britain

Sexton, J. (2008). From Art to Avant Garde? Television, Formalism and the Arts Documentary in 1960's Britain. In L. Mulvey and J. Sexton (Eds.), Experimental British Television (pp.89-105). Manchester: Manchester University Press. RAE2008

The architecture of influence: Paul Rudolph's Art and Architecture Building at Yale

Focussing on Paul Rudolph’s Art & Architecture Building at Yale, this thesis demonstrates how the building synthesises the architect’s attitude to architectural education, urbanism and materiality. It tracks the evolution of the building from its origins – which bear a relationship to Rudolph’s pedagogical ideas – to later moments when its occupants and others reacted to it in a series of ways that could never have been foreseen. The A&A became the epicentre of the university’s counter culture movement before it was ravaged by a fire of undetermined origins. Arguably, it represents the last of its kind in American architecture, a turning point at the threshold of postmodernism. Using an archive that was only made available to researchers in 2009, this is the first study to draw extensively on the research files of the late architectural writer and educator, C. Ray Smith. Smith’s 1981 manuscript about the A&A entitled “The Biography of a Building,” was never published. The associated research files and transcripts of discussions with some thirty interviewees, including Rudolph, provide a previously unavailable wealth of information. Following Smith’s methodology, meetings were recorded with those involved in the A&A including, where possible, some of Smith’s original interviewees. When placed within other significant contexts – the physicality of the building itself as well as the literature which surrounds it – these previously untold accounts provide new perspectives and details, which deepen the understanding of the building and its place within architectural discourse. Issues revealed include the importance of the influence of Louis Kahn’s Yale Art Gallery and Yale’s Collegiate Gothic Campus on the building’s design. Following a tumultuous first fifty years, the A&A remains an integral part of the architectural education of Yale students and, furthermore, constitutes an important didactic tool for all students of architecture.

Placement of Small Vertical Axis Wind Turbine to Maximize Power Generation Influenced by Architectural and Geographic Interfaces in Urban Areas

Current methods for large-scale wind collection are unviable in urban areas. In order to investigate the feasibility of generating power from winds in these environments, we sought to optimize placements of small vertical-axis wind turbines in areas of artificially-generated winds. We explored both vehicular transportation and architecture as sources of artificial wind, using a combination of anemometer arrays, global positioning system (GPS), and weather report data. We determined that transportation-generated winds were not significant enough for turbine implementation. In addition, safety and administrative concerns restricted the implementation of said wind turbines along roadways for transportation-generated wind collection. Wind measurements from our architecture collection were applied in models that can help predict other similar areas with artificial wind, as well as the optimal placement of a wind turbine in those areas.

High current density induced damage mechanisms in electronic solder joints: a state-of-the-art review

High current density induced damages such as electromigration in the on-chip interconnection /metallization of Al or Cu has been the subject of intense study over the last 40 years. Recently, because of the increasing trend of miniaturization of the electronic packaging that encloses the chip, electromigration as well as other high current density induced damages are becoming a growing concern for off-chip interconnection where low melting point solder joints are commonly used. Before long, a huge number of publications have been explored on the electromigration issue of solder joints. However, a wide spectrum of findings might confuse electronic companies/designers. Thus, a review of the high current induced damages in solder joints is timely right this moment. We have selected 6 major phenomena to review in this paper. They are (i) electromigration (mass transfer due electron bombardment), (ii) thermomigration (mass transfer due to thermal gradient), (iii) enhanced intermetallic compound growth, (iv) enhanced current crowding, (v) enhanced under bump metallisation dissolution and (vi) high Joule heating and (vii) solder melting. the damage mechanisms under high current stressing in the tiny solder joint, mentioned in the review article, are significant roadblocks to further miniaturization of electronics. Without through understanding of these failure mechanisms by experiments coupled with mathematical modeling work, further miniaturization in electronics will be jeopardized

To tremble the zero: art in the age of algorithmic reproduction

'To Tremble the Zero: Art in the Age of Algorithmic Reproduction' is a philosophic, political and sensuous journey playing with (and against) Benjamin's 'Art in the Age of Mechanical Reproduction'. In an age inundated by the 'post-': postmodernity, posthuman, post art, postsexual, post-feminist, post-society, post-nation, etc, 'To Tremble the Zero' sets out to re/present the nature of what it means to do or make 'art', as well as what it means to be or have 'human/ity' when the ground is nothing other than the fractal, and algorithmically infinite, combinations of zero and one. The work will address also the unfortunate way in which modern forms of metaphysics continue to creep 'unsuspectingly' into our understanding of contemporary media/electronic arts, despite (or perhaps even because of) the attempts by Latour, Badiou, or Agamben especially when addressing the zero/one as if a contradictory 'binary' rather than as a kind of 'slice' or (to use Deleuze and Guattari) an immanent plane of immanence. This work argues that by retrieving Benjamin, Einstein, Gödel, and Haraway, a rather different story of art can be told.

Hide and seek with rebels: tracing contemporary queer art in cracks and rips

This Article does not have an abstract.

Creative environments for art, craft & design teaching in the 21st century

This booklet has been designed for student teachers in particular and those in their early years as teachers of art, craft and design. It is suitable however for all teachers of art and design, and will be useful when considering the 2007 review of the Art and Design programme of study (POS) with its focus on creativity and ideas developments. The contents are intended as prompts or guides and ideas for initiating individual responses to themes or projects and a "way in" for the teacher when guiding pupils. It explains in detail how one might inspire all groups with appropriate and varied resources.