Melody based tune retrieval over the World Wide Web

In this paper we describe the steps taken to develop a Web-based version of an existing stand-alone, single-user digital library application for melodical searching of a collection of music. For the three key components: input, searching, and output, we assess the suitability of various Web-based strategies that deal with the now distributed software architecture and explain the decisions we made. The resulting melody indexing service, known as MELDEX, has been in operation for one year, and the feed-back we have received has been favorable

Mapping the optical properties of slab-type two-dimensional photonic crystal waveguides

We report on systematic experimental mapping of the transmission properties of two-dimensional silicon-on-insulator photonic crystal waveguides for a broad range of hole radii, slab thicknesses and waveguide lengths for both TE and TM polarizations. Detailed analysis of numerous spectral features allows a direct comparison of experimental data with 3D plane wave and finite-difference time-domain calculations. We find, counter-intuitively, that the bandwidth for low-loss propagation completely vanishes for structural parameters where the photonic band gap is maximized. Our results demonstrate that, in order to maximize the bandwidth of low-loss waveguiding, the hole radius must be significantly reduced. While the photonic band gap considerably narrows, the bandwidth of low-loss propagation in PhC waveguides is increased up to 125nm with losses as low as 8$\pm$2dB/cm.Comment: 10 pages, 8 figure

A wireless ultrasonic NDT sensor system

Ultrasonic condition monitoring technologies have been traditionally utilized in industrial and construction environments where structural integrity is of concern. Such techniques include active systems with either single or multiple transmit-receiver combinations used to obtain defect positioning and magnitude. Active sensors are implemented in two ways; in a thickness operation mode, or as an area-mapping tool operating over longer distances. In addition, passive ultrasonic receivers can be employed to detect and record acoustic emission activity. Existing equipment requires cabling for such systems leading to expensive, complicated installations. This work describes the development and operation of a system that combines these existing ultrasonic technologies with modern wireless techniques within a miniaturized, battery-operated design. A completely wireless sensor has been designed that can independently record and analyze ultrasonic signals. Integrated into the sensor are custom ultrasonic transducers, associated analogue drive and receive electronics, and a Texas Instruments Digital Signal Processor (DSP) used to both control the system and implement the signal processing routines. BlueTooth wireless communication is used for connection to a central observation station, from where network operation can be controlled. Extending battery life is of prime importance and the device employs several strategies to do this. Low voltage transducer excitation suffers from poor signal-to-noise ratios, which can be enhanced by signal processing routines implemented on the DSP. Routines investigated include averaging, digital filtering and pulse compression

A Zooarchaeological and Paleoclimate Analysis of Gadus Morhua Otoliths Recovered from the Sandwick South Site, Shetland Islands, United Kingdom

The Shetland Islands are an archipelago 240 km northeast of the northern tip of mainland Scotland and 360 km west of Bergen, Norway (Figure 1.1). The Gulf Stream, which flows from the Gulf of Mexico to the coast of Norway, passes along the western side of the Shetland Islands, leading to a warmer climate than would be predicted by their latitude. On the eastern side lay the colder waters of the North Sea, which also impact the climate of the islands. During the period in which the Sandwick South site was inhabited, 1100-1350 AD, paleoclimate reconstructions show a transition from a warmer period, the Medieval Climatic Optimum, to a distinctly cooler period, the Little Ice Age (Mann 2009). This transition has not been heavily studied in the Shetland Islands, as the acidic, non-arable soils of the Shetland environment makes many paleotemperature proxies difficult to reassemble. One paleotemperature record that can be used in the Shetland Islands is the otolith record, in which the 18O values of aragonite from inner ear bones of fish are utilized to reconstruct paleotemperature at the time the fish lived. These inner ear bones are collected from midden units within settlements. In addition to paleotemperature data, otoliths can also reveal information about the fishing methods of the inhabitants of the islands and ecological impact that the fishing had on the fish population. Refining our knowledge of paleoclimate records can not only help to understand the potential future shifting of climate systems, but can also be a valuable tool in determining the effect that climate has on people living in the environment. Fish otoliths are an especially important source of information for a society heavily dependent on fishing for its livelihood, as they can provide a high resolution record throughout the inhabitation of a site

Transmission of Slow Light through Photonic Crystal Waveguide Bends

The spectral dependence of a bending loss of cascaded 60-degree bends in photonic crystal (PhC) waveguides is explored in a slab-type silicon-on-insulator system. Ultra-low bending loss of (0.05+/-0.03)dB/bend is measured at wavelengths corresponding to the nearly dispersionless transmission regime. In contrast, the PhC bend is found to become completely opaque for wavelengths range corresponding to the slow light regime. A general strategy is presented and experimentally verified to optimize the bend design for improved slow light transmission.Comment: 4 pages, 3 figures; submitted to Optics Letter