No description available.

No description available.

ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / In this paper we will present a new fiber sensor integrated monitor (FSIM) to be used in an embedded instrumentation system (EIS). The proposed system consists of a super luminescent diode (SLD) as a broadband source, a novel high speed tunable MEMS filter with built in photodetector, and an integrated microprocessor for data aggregation, processing, and transmission. As an example, the system has been calibrated with an array of surface relief fiber Bragg gratings (SR-FBG) for high speed, high temperature monitoring. The entire system was built on a single breadboard less than 50 cm² in area.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / This paper describes the design, configuration, testing, and performance of a Fiber Optic Link used to transmit the signals from a remotely located S-band telemetry system to the main facility at the Kwajalein Missile Range (KMR). This fiber optic system demonstrates for the first time the feasibility of linking RF data from multiple antennas via a single fiber and over a nearly 100-km distance. Measured data of key link parameters such as gain, bit-error-rate, crosstalk, phase and gain stability, dynamic range, and noise figure are presented.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / An advanced electro-optic hybrid rotary joint (EOHRJ) has been developed in Phase II of an AF SBIR effort with Physical Optics Corporation (POC) to replace cable wrap structure for multi-channel rotation-to-fixed (RTF) signal transmission. The EOHRJ meets AFFTC and other range special needs with a generic, high performance, rotary joint solution. At the moment, we have successfully installed and tested the EOHRJ on our KTM tracker system with the following capabilities: 1) able to accommodate hundreds of transmission channels, including electrical power, control, feedback, and low-speed signals; 2) able to accommodate multiple channel, high data rate (over gigabits per second), and bi-directional signal transmission; 3) able to be reliable for harsh environmental operation, adaptive to stringent sized requirement, and accommodating existing electrical and mechanical interfaces. The completed EOHRJ contains three uniquely integrated functional rings. The first and the outmost one is power ring, which provides RTF transmission channels for over 50 high voltage and high current channels. The second and the middle one is low speed electrical signal ring, which provides RTF transmission for over hundred control, feedback, and low speed data signals. The third and the inmost one is optical fiber slip ring, which, incorporating with current advanced signal multiplexing technologies (either time division or wavelength division multiplexing ) is able to provide multiple channel, high data rate, and bi-directional signal transmission. At the moment, the prototype module of the tree-layer EOHRJ has been successfully assembled in Air Force’s tracker system, and is providing a satisfactory performance. This paper presents our joint work on this project.

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

<p>Paper that is subjected to moisture undergoes dimensional changes. It expands during moistening and shrinks during drying. When the paper is under tension between rollers, the effects are complex since shrinkage and expansion are restricted in the width direction. Waves can then appear on the paper web. This can be a problem in heatset web offset printing. The problem is known as waviness or fluting. The printed papers exhibit a wavy shape, which is visually disturbing due to light reflections which create glossy streaks. The aim of the work described in this thesis was to develop a method suitable for studying the moisture- and tension-induced waviness. Experiments were carried out on a laboratory scale to study how such waves develop during moistening and drying. The experimental setup was based on a modified tensile tester. A CCD camera and image analysis based on the STFI-OptiTopo technique was used to characterise the waviness. Moistening and drying were achieved by changing the surrounding air humidity. The method was used to study the effect of moisture uptake by the paper, and to evaluate the effect of tension on the waviness. It was found that increasing moisture resulted in a higher waviness amplitude, but that the web tension controlled the wavelength of the waviness. A high tension gave rise to a shorter wavelength. The measured wavelength was compared with a previously suggested model and the predicted wavelength was about twice as high as the measured wavelength.</p> / <p>When paper becomes damp it can develop waves which can be a problem with heatset web offset printing. Paper with waves may have glossy streaks after printing. Laboratory experiments studied the effect of moisture uptake by the paper. Readings were taken at a range of air humidities. The effect of tension on the waviness was also measured. The waviness was characterised using a charge coupled device (CCD) camera and the STFI-Packforsk OptiTopo technique to analyse the images. When the humidity was increased the amplitude of the waves increased. A high tension resulted in shorter wavelengths. Results from a previous model were used as a comparison.</p>

No description available.

We present an analysis of the properties of HI holes detected in 20 galaxies that are part of “The HI Nearby Galaxy Survey” (THINGS). We detected more than 1000 holes in total in the sampled galaxies. Where they can be measured, their sizes range from about 100 pc (our resolution limit) to about 2 kpc, their expansion velocities range from 4 to 36 km/s, and their ages are estimated to range between 3 and 150 Myr. The holes are found throughout the discs of the galaxies, out to the edge of the HI disc; 23% of the holes fall outside R25. We find that shear limits the age of holes in spirals; shear is less important in dwarf galaxies which explains why HI holes in dwarfs are rounder, on average than in spirals. Shear, which is particularly strong in the inner part of spiral galaxies, also explains why we find that holes outside R25 are larger and older. We derive the scale height of the HI disc as a function of galactocentric radius and find that the disc flares at large radii in all galaxies. We proceed to derive the surface and volume porosity (Q2D and Q3D) and find that this correlates with the type of the host galaxy: later Hubble types tend to be more porous. The size distribution of the holes in our sample follows a power law with a slope of a=−2.9. Assuming that the holes are the result of massive star formation, we derive values for the supernova rate (SNR) and star formation rate (SFR) which scales with the SFR derived based on other tracers. If we extrapolate the observed number of holes to include those that fall below our resolution limit, down to holes created by a single supernova, we find that our results are compatible with the hypothesis that HI holes result from star formation. We use HI data from THINGS, 8μm, 24μm, 70μm and HI maps from SINGS, CO(2–1) data from HERACLES and FUV data from NGS to present a visual comparison of these maps with respect to the locations of HI holes. We find that the vast majority of HI holes are also prominent in the 8μm map and to some extent in the 24μm map. There is a lack of molecular gas from the interior of nearly all the holes, which is consistent with the idea that the latter are filled with hot gas. About 60% of young holes have FUV emission detected in their interiors highlighting the presence of the parent OB association. In addition, FUV is detected on the rims of some of the older HI holes, presumably due to the dispersion of the OB association with respect to the gas. We describe the development of a 2–D cross-correlation method to compare multi-wavelength maps in a quantitative way (quantified by Ccoef ) and give some first results from the application of this method to the nearby galaxy NGC2403. We find that the all the dust tracers are well correlated (Ccoef > 0.7) with the 8μm–24μm correlation being the highest (Ccoef > 0.88). Similarly all the star formation tracers are well linked as expected (Ccoef > 0.6). With respect to the relations between star formation and dust tracers we found that most are well matched (Ccoef > 0.7) as dust grains are heated by radiation in star forming regions. At smaller scales (15") FUV correlates poorly (Ccoef ~ 0.3) with the dust tracers, a direct consequence of the absorption of FUV photons by dust. We find that the HI is reasonably well correlated with the 8μm emission (Ccoef ~ 0.6) illustrating the fact that HI is mixed with PAH’s. Interestingly, the HI map shows some correlation with the SF map (Ccoef ~ 0.4) even though FUV and HI emissions were found to be completely uncorrelated (Ccoef ~ 0).

The two SCUBA HAlf-Degree Extragalactic Survey (SHADES) fields are amongst the richest places in the sky in terms of multi-wavelength coverage. They comprise an eastern section of the Lockman Hole (LH) and the central portion of the Subaru- XMM/Newton Deep Field (SXDF). In this thesis, I have obtained extremely deep, multi-frequency radio imaging of the SHADES fields using the GiantMetre-wave Radio Telescope (GMRT) and the Very Large Array (VLA), at 610MHz and 1.4GHz, respectively. These data are used to analyse the nature of the sub-milliJansky (sub-mJy) radio population, which has been hotly debated in the last few years: are they powered by star-forming or nuclear activity? To tackle the problem, I employ different approaches making use of the large variety of multi-wavelength data in the SHADES fields. I begin by analysing the spectral index, α610MHz 1.4GHz , of radio sources detected in the LH, to explore the dominant emission mechanism. Based on a robust 10 σ detection criterion, I find a constantmedian spectral index of α610MHz 1.4GHz ≈ −0.6 to −0.7 for sources between S1.4GHz ≈ 200 μJy and 10mJy. This result suggests that the galaxy population in the sub-mJy regime is powered by optically-thin synchrotron emission – starforming galaxies or lobe-dominated active galactic nuclei (AGN). Making use of X-ray observations in the LH, I show that the fraction of radio sources detected in the hard X-ray band (between 2 and 10 keV) decreases from 50 to 15 per cent between S1.4GHz ≈ 1mJy and . 100 μJy, which strongly suggests a transition from AGN to star-forming galaxies. Based on the deep, multi-wavelength coverage of the SXDF, I explore the behaviour of the far-infrared (FIR)/radio correlation as a function of redshift. I combine the q24 factor – the logarithmic flux density ratio between Spitzer 24-μm and VLA 1.4- GHz flux densities – with available photometric redshifts and find strong evidence that the correlation holds out to z ≈ 3.5. Based on M82-like k-corrections and using a high-significance (S1.4GHz > 300 μJy) radio sub-sample, I find a mean and scatter of q24 = 0.71 ± 0.47. Monte-Carlo simulations based on these findings show that fewer sources deviate from the correlation at fainter flux densities (i.e. fewer radioloud AGN). I predict that the radio-loud fraction drops from 50 per cent at ∼ 1mJy to zero at . 100 μJy. The validity of the FIR/radio correlation out to very high redshifts adds credibility to identifications of sub-millimetre (submm) galaxies (SMGs) made at radio wavelengths. Based on a sample of 45 radio-identified SMGs in the LH, I find a median radio spectral index of α610MHz 1.4GHz = −0.72 ± 0.07, which suggests that optically-thin synchrotron is the dominant radio emission mechanism. Finally, as anAppendix I include a theoretical treatment that constrains the average geometry of the dusty, torus-like structures believed to obscure a large fraction of the AGN population. I use the distribution of column densities (NH) obtained from deep ∼ 1Msec X-ray observations in the Chandra Deep Field South. I find that to reproduce the wide observed range of NH, the best torus model is given by a classical “donut”- shaped distribution with an exponential angular dependency of the density profile.