Project Management Component - for Flygprestanda AB's web system

Flygprestanda AB make software and databases for hundreds of airline companies all over the world. Their services include both software development and technical-engineering calculations with focus on delivering all information needed to perform a commercial flight from one place to another. The company is currently developing a web system with Google Web Toolkit which will be used within the company. There is also a possibility that the system will be sold to other companies in the future. An important part of the system is a component which allows the user to plan, schedule and review tasks contained in Flygprestanda AB’s daily operations. During the thesis describe in this report the best way to realise this component has been researched. An initial investigation has concentrated on finding a suitable project management technique on which to base the component, and how to practically implement it. The project management techniques have been compared based on what information they can present and the possibility to realise them with software. Flyprestanda AB’s current way of managing projects has also been taken into account. The chosen technique is the Gantt chart, which satisfies the demands. The investigation has also compared the advantages and disadvantages of developing the project management component from the ground up or using an existing solution. For the purpose of finding a programming language to use if the component was to be developed from scratch, a variety of web programming languages such as Adobe Flash and JavaScript have been compared. Different existing solutions, such as FusionWidgets and EJS TreeGrid, have been investigated with focus on their presentation- and interaction capabilities, their ways to communicate with a database, and to some extent their available licenses and offered support. The decision made during the investigation was not to develop the component from the ground up, but to integrate an existing component, namely the JavaScript solution EJS TreeGrid. The integration of EJS TreeGrid was realised by adapting the component and placing it in the web system's interface trough JSNI, and writing code that made it able to communicate with the system’s MySQL database. A component intended to provide a way of managing milestones in a project, the GWT-YUI-Carousel, was added later during the work. This component was also adapted to the system and its database

Design and Optimization of Dual Band Circular Polarization Selective Structures

We present a non-resonant, dual band circular polarization selective structure (CPSS) for satellite communication applications in the K- and Ka-band. The structure consists of multiple layers of cascaded anisotropic sheets, with printed meander lines, separated by low permittivity spacers. It reflects right hand circular polarization and transmits left hand circular polarization in the lower frequency band. In the upper frequency band the opposite polarization selectivity is achieved. The theory of dual band circular polarization selectivity from cascaded anisotropic sheets is presented, and it is concluded that the separation between the frequency bands of operation is governed by the relative rotation between subsequent layers. An optimization routine for synthesizing dual band CPSSs from predefined design requirements is introduced, where a number of different optimization algorithms are utilized. A simulated design is presented which fulfills the strict design requirements of insertion loss and return loss less than 0.5dB, and axial ratio less than 0.78dB, in the frequency bands 17.7–20.2GHz and 27.5–30.0GHz. A prototype of the optimized design has been fabricated and characterized experimentally, both in transmissionandreflection,andgoodagreementisobservedbetweensimulated and experimental results. This type of structure is a potential candidate for implementation in dual band multiple spot beam systems utilizing frequency and polarization reuse schemes

A new view on the ISM of galaxies: far-infrared and submillimetre spectroscopy with Herschel

The FIR/submm window is amongst the least explored spectral regions of the electromagnetic spectrum. It is, however, a key to study the general properties of the interstellar medium of galaxies, as it contains important spectral line diagnostics from the neutral, ionized and molecular ISM. The Herschel Space Observatory, successfully launched on 14 May 2009, is the first observatory to cover the entire FIR/submm range between 57 and 672 mum. We discuss the main results from the ISO era on FIR spectroscopy of galaxies and the enormous science potential of the Herschel mission through a presentation of its spectroscopic extragalactic key programs.Comment: 10 pages, 4 figures, accepted for publication in New Astronomy Review

Monitoring corrosion-induced concrete cracking adjacent to the steel-concrete interface

Substantial research effort has been devoted on linking corrosion-induced cracking of concrete with the internal corrosion damage level. Still, numerical models of the corrosion and cracking process require internal parameters, that cannot be directly evaluated from experimental data. Therefore, this study provides a novel experimental method for monitoring the effects of steel corrosion adjacent to the steel-concrete interface. This non-destructive method is suited for small-scale laboratory-made specimen, and was designed to provide missing information required for subsequent calibration of numerical models. Hollow steel bars were cast into concrete and subjected to accelerated corrosion using the impressed current technique. The deformations of the hollow steel bars were measured using distributed strain sensing in an optical fibre, attached to the inner surface of the hollow steel bars. After the corrosion period, X-ray Computed Tomography scans were performed to evaluate concrete cracking and corrosion level. The results reveal a non-uniform distribution of strain around the perimeter of the steel, indicating a non-uniform radial stress distribution. The non-uniformity correlated very well with the position of the corrosion-induced cracks; with extension hoop strains in the steel at the location of these cracks and contraction hoop strains in between. Further, the corrosion level varied around the perimeter, with higher values near cracks. The combination of non-destructive monitoring techniques used in this study on small-scale laboratory-made specimens show great potential to reveal new insights on how the corrosion pattern, corrosion-induced cracking of the concrete cover and stress (indirectly measured through the strain in the steel) interact throughout the corrosion process

Wild boar (Sus scrofa) has minor effects on soil nutrient and carbon dynamics

Wild boar populations have increased worldwide, but the consequences of their disturbances on boreal forest ecosystems are largely unknown. We investigated how wild boars affect soil processes in a Swedish boreal forest. We estimated effects on ecosystem functioning using phospholipid fatty acid analyses (PLFA) to characterise microbial groups, and by measuring soil respiration, soil carbon (C), nitrogen (N) and phosphorus (P) concentrations, as well as the availability of NO3- and NH4+. We compared samples collected inside wild boar enclosures with adjacent reference areas without wild boar disturbance. We found no difference in soil microbial composition, except for a consistently higher fungi:bacteria ratio in the enclosures. These results are contrary to our hypothesis that rooting raises nitrogen levels, which in turn result in more bacteria. Soil nutrient levels showed inconsistent patterns, suggesting that substrate changes - as opposed to nutrient changes - stimulated fungal growth. Soil respiration was lower in the enclosures, contradicting earlier findings suggesting increased soil CO2 emissions from wild boar rooting. Overall, our study suggests that increased wild boar abundance has a minor impact on soil processes in boreal forests. Future studies should determine if the modest impacts remain across time and boreal forests

Atomic clocks as a tool to monitor vertical surface motion

Atomic clock technology is advancing rapidly, now reaching stabilities of $\Delta f/f \sim 10^{-18}$, which corresponds to resolving $1$ cm in equivalent geoid height over an integration timescale of about 7 hours. At this level of performance, ground-based atomic clock networks emerge as a tool for monitoring a variety of geophysical processes by directly measuring changes in the gravitational potential. Vertical changes of the clock's position due to magmatic, volcanic, post-seismic or tidal deformations can result in measurable variations in the clock tick rate. As an example, we discuss the geopotential change arising due to an inflating point source (Mogi model), and apply it to the Etna volcano. Its effect on an observer on the Earth's surface can be divided into two different terms: one purely due to uplift and one due to the redistribution of matter. Thus, with the centimetre-level precision of current clocks it is already possible to monitor volcanoes. The matter redistribution term is estimated to be 2-3 orders of magnitude smaller than the uplift term, and should be resolvable when clocks improve their stability to the sub-millimetre level. Additionally, clocks can be compared over distances of thousands of kilometres on a short-term basis (e.g. hourly). These clock networks will improve our ability to monitor periodic effects with long-wavelength like the solid Earth tide.Comment: 11 pages, 5 figures, accepted as express letter in the Geophysical Journal Internationa

Probing the Dust Properties of Galaxies up to Submillimetre Wavelengths I. The Spectral Energy Distribution of dwarf galaxies using LABOCA

We present 870 micron images of four low metallicity galaxies (NGC1705, Haro11, Mrk1089 and UM311) observed with the Large APEX BOlometer CAmera (LABOCA). We model their spectral energy distributions combining the submm observations of LABOCA, 2MASS, IRAS, Spitzer photometric data and the IRS data for Haro11. We find that a significant mass of dust is revealed when using submm constraints compared to that measured with only mid-IR to far-IR observations extending only to 160 microns. For NGC1705 and Haro11, an excess in submillimeter wavelengths is detected and we rerun our SED procedure adding a cold dust component (10K) to better describe the high 870 micron flux derived from LABOCA observations, which significantly improves the fit. We find that at least 70% of the dust mass of these two galaxies can reside in a cold dust component. We also show that the subsequent dust-to-gas mass ratios, considering HI and CO observations, can be strikingly high for Haro11 in comparison with what is usually expected for these low-metallicity environments. Furthermore, we derive the SFR of our galaxies and compare them to the Schmidt law. Haro11 falls anomalously far from the Schmidt relation. These results may suggest that a reservoir of hidden gas could be present in molecular form not traced by the current CO observations. We also derive the total IR luminosities derived from our models and compare them with relations that derive this luminosity from Spitzer bands. We find that the Draine & Li (2007) formula compares well to our direct IR determinations.Comment: 22 pages, 7 figures, 10 tables, accepted for publication in A&

Fundamental bounds on transmission through periodically perforated metal screens with experimental validation

This paper presents a study of transmission through arrays of periodic sub-wavelength apertures. Fundamental limitations for this phenomenon are formulated as a sum rule, relating the transmission coefficient over a bandwidth to the static polarizability. The sum rule is rigorously derived for arbitrary periodic apertures in thin screens. By this sum rule we establish a physical bound on the transmission bandwidth which is verified numerically for a number of aperture array designs. We utilize the sum rule to design and optimize sub-wavelength frequency selective surfaces with a bandwidth close to the physically attainable. Finally, we verify the sum rule and simulations by measurements of an array of horseshoe-shaped slots milled in aluminum foil.Comment: 10 pages, 11 figures. Updated Introduction and Conclusion