Urban economic theory states that transit improvements result in travel time savings and consequently warrant higher rents particularly with proximity to surrounding stations. This research uses the Sheppard subway corridor as a case study to test the established theories by measuring the changes to residential intensification and property values (1) as a function of time before and after the construction, and (2) as a function of distance to subway stations. Two metrics are established to observe residential intensification and property value: Dwelling Density and Value Density respectively. Dwelling Density is the number of dwellings contained in its property parcel divided by property area; Value Density is total property value of a given property parcel divided by its property area. Using obtained property sales data in four identified analysis years (1991, 1996, 2001, and 2006) and ArcGIS, spatial interpolation surfaces are generated to visualize the changes on a geographical plane through time. Dwelling and Value Density scatterplots are generated by extracting values from the interpolated surfaces and computing its distance to the nearest subway station and to major development nodes. The generated interpolated surfaces show a strong increase in Dwelling and Value Density in North York Centre which suggest that (1) planning policies succeeded in guiding residential growth, (2) a time lag is present of which the full benefits of rapid transit construction are realized, and (3) there may be positive network effects associated with the completion of the Sheppard subway. The scatterplot results demonstrated moderate change in Dwelling and Value Density at the Bayview station area and little change for the remaining stations (Bessarion, Don Mills, and Leslie) based on observations up to December 2006. The results warrant a degree of optimism about Sheppard subway’s ability to attract residential intensification and raise property values, especially given that data was analyzed only up to four years after the subway corridor began revenue service. It is recommended that a similar methodology be performed at a later date when the corridor’s ridership and surrounding development reaches maturity. A preliminary forecasting exercise determined that Dwelling and Value Density will rise, particularly surrounding stations that have since demonstrated little change in residential land use.

Contemporary algorithms employed for reconstruction of 3D volumes from helical cone beam projections are so called non-exact algorithms. This means that the reconstructed volumes will contain artifacts irrespective of the detector resolution and number of projections angles employed in the process. It has been proposed that these artifacts can be suppressed using an iterative scheme which comprises computation of projections from the already reconstructed volume as well as the non-exact reconstruction itself. The purpose of the present work is to examine if the iterative scheme can be applied to the non-exact reconstruction method PI-original in order to improve the reconstruction result. An important part in this implementation is a careful design of the projection operator, as a poorly designed projection operator may result in aliasing and/or other artifacts in the reconstruction result. Since the projection data is truncated, special care must be taken along the boundaries of the detector. Three different ways of handling this interpolation problem is proposed and examined. The results show that artifacts caused by the PI-original method can indeed be reduced by the iterative scheme. However, each iteration requires at least three times more processing time than the initial reconstruction, which may call for certain compromises, smartness and/or parallelization in the innermost loops. Furthermore, at higher cone angles certain types of artifacts seem to grow by each iteration instead of being suppressed.

A modality device can today capture high resolution volumetric data sets and as the data resolutions increase so does the challenges of processing volumetric data through a visualization pipeline. Standard volume rendering pipelines often use a graphic processing unit (GPU) to accelerate rendering performance by taking beneficial use of the parallel architecture on such devices. Unfortunately, graphics cards have limited amounts of video memory (VRAM), causing a bottleneck in a standard pipeline. Multi-resolution techniques can be used to efficiently modify the rendering pipeline, allowing a sub-domain within the volume to be represented at different resolutions. The active resolution distribution is temporarily stored on the VRAM for rendering and the inactive parts are stored on secondary memory layers such as the system RAM or on disk. The active resolution set can be optimized to produce high quality renders while minimizing the amount of storage required. This is done by using a dynamic compression scheme which optimize the visual quality by evaluating user-input data. The optimized resolution of each sub-domain is then, on demand, streamed to the VRAM from secondary memory layers. Rendering a multi-resolution data set requires some extra care between boundaries of sub-domains. To avoid artifacts, an intrablock interpolation (II) sampling scheme capable of creating smooth transitions between sub-domains at arbitrary resolutions can be used. The result is a highly optimized rendering pipeline complemented with a preprocessing pipeline together capable of rendering large volumetric data sets in real-time.

Ingen vätska kan ersätta vatten och utan vatten kan inget liv existera. Markens fysikaliska egenskaper och kemiska förhållanden styr spridningen av de föroreningsämnen som före¬kommer i mark och i vatten. Katrineholms kommun vill i framtiden kunna utnyttja vattenmagasinen i Forssjö. Ett antal observationsrör har placerats i Forssjö, vilket är beläget cirka 8 km sydost om Katrineholm. I dagsläget används inte GIS i kommunen och detta gjorde att jag blev intresserad av vilka möjligheter som GIS skulle kunna tillföra med utgångspunkt i den brunnsdatabas med vatten¬kvalitetsmätningar som finns i kommunen. Detta examensarbete består av två delar. Den första delen granskar risken för föroreningar från den del av väg 52 mellan Katrineholm och Nyköping som passerar Katrineholmsåsen sydost om Katrineholm. Inom riskkartan visade det sig att de jordlager som täcker akviferen, Katrineholmsåsen, inte ger naturligt skydd åt grundvattnet mot nedträngande föroreningarna. Den metod som används för att beräkna riskerna för förorenat grundvatten är den hydrogeologiska sårbarhetsmodell som Lena Maxe och Per-Olof Johansson har utarbetat i Bedömning av grundvattnets sårbarhet, 1998. I Katrineholms kommun finns fullständiga data om jordarter och en utmärkt brunnsdatabas. För att utredda risken för en förorening av akviferen i Katrineholmsåsen från väg 52, behövs ett bra verktyg. Detta arbete kommer att visa hur och på vilka sätt GIS kan utföra detta. Under arbetets gång har kontakt tagits med Räddningsverket i Karlstad. Via den kontakten har mycket värdefull information skaffats, till exempel hur genomströmnings¬hastigheter beräknas för föroreningsämnen, vilka program som de använder för att beräkna risker vid spill och utsläpp av kemikalier. I andra delen av mitt arbete har jag granskat vilken metod som lämpar sig bäst för interpolering av situationen mellan mätpunkterna; kriging eller cokriging, i geostatistiska analyser. För att hitta den bäst anpassade modellen har jag använt ekvationen: fel = r = ύ – v. Här gäller det att söka en modell som ger felet ett värde så nära noll som möjligt. Utryckning vid utsläpp av bensin, diesel och övriga petroleumprodukter utgjorde 75 % av fallen enligt Räddningsverket insatsstatistik 2000 – 2003. Dessa ämnen ingår i gruppen kemikalier med benämningen NAPL, Non Aqueous Phase Liquid. I mitt arbete har jag koncentrerat mig på hur utsläpp av denna grupp av kemikalier på väg 52 skulle kunna förorena akviferen i Katrineholmsåsen.

Dynamic building simulation is increasingly necessary for accurately quantifying potential energy savings measures in retrofit projects, to compliant with new stricter directives from EU implanted into member states legislations and building codes. For good result the simulation model need to be accurately calibrated. This requires actual weather data, representative for the climate surrounding the given building, in order to calibrate against actual energy bills of the same period of time. The main objective of this degree project is to combine observed weather (temperature, humidity, wind etc.) data with modeled solar radiation data, utilizing the SMHI STRÅNG model system; and transform these data into AMY (Actual Meteorological Year) files to be used with building simulation software. This procedure gives actual weather datasets that will cover most of the urban and semi urban area in Northern Europe while still keeping the accuracy of observed weather data. A tool called Real-Time Weather Converter was developed to handle data retrieval & merging, filling of missing data points and to create the final AMY-file. Modeled solar radiation data from STRÅNG had only been validated against a Swedish solar radiation network; validation was now made by the author with wider geographic coverage. Validation results show that STRÅNG model system performs well for Sweden but less so outside of Sweden. There exist some areas outside of Sweden (mainly Central Europe) with reasonable good result for some periods but the result is not as consistent in the long run as for Sweden. The missing data fill scheme developed for the Real-Time Weather Converter does perform better than interpolation for data gaps (outdoor temperature) of about 9 to 48 hours. For gaps between 2 and 5 days the fill scheme will still give slightly better result than linear interpolation. Akima Spline interpolation performs better than linear interpolation for data gaps (outdoor temperature) in the interval 2 to about 8 hours. Temperature uncertainty was studied using data from the period 1981-2010 for selected sites. The result expressed as SD (Standard Deviation) for the uncertainty in yearly mean temperature is about 1˚C for the Nordic countries. On a monthly basis the variation in mean temperature is much stronger (for Nordic countries it ranges from 3.5 to 4.7 ˚C for winter months), while summer months have less variation (with SD in the range of 1.3 to 1.9 ˚C). The same pattern is visible in sites at more southern latitudes but with much lower variation, and still lower for sites near coast areas. E.g. the cost-near Camborne, UK, has a SD of 0.7 to 1.7 ˚C on monthly basis and yearly SD of 0.5 ˚C. Mean direct irradiance SD for studied sites ranges from 5 to 19 W/m2 on yearly basis, while on monthly basis the SD ranges from 40 to 60 W/m2 for summer months. However, the sample base was small and of inconsistent time periods and the numbers can only be seen as indicative. The commonly used IWEC (International Weather for Energy Calculations) files direct radiation parameter was found to have a very strong negative bias of about 20 to 40 % for Northern Europe.  These files should be used with care, especially if solar radiation has a significant impact of on the building being modeled. Note that there exist also a newer set of files called IWEC2 that can be purchased from ASHRAE, these files seems not to be systematically biased for North Europe but haven’t been studied in this paper. The STRÅNG model system does catch the trend, also outside of Sweden, and is thus a very useful source of solar radiation data for model calibration.

We present a numerical inversion method for generating random variates from continuous distributions when only the density function is given. The algorithm is based on polynomial interpolation of the inverse CDF and Gauss-Lobatto integration. The user can select the required precision which may be close to machine precision for smooth, bounded densities; the necessary tables have moderate size. Our computational experiments with the classical standard distributions (normal, beta, gamma, t-distributions) and with the noncentral chi-square, hyperbolic, generalized hyperbolic and stable distributions showed that our algorithm always reaches the required precision. The setup time is moderate and the marginal execution time is very fast and the same for all distributions. Thus for the case that large samples with fixed parameters are required the proposed algorithm is the fastest inversion method known. Speed-up factors up to 1000 are obtained when compared to inversion algorithms developed for the specific distributions. This makes our algorithm especially attractive for the simulation of copulas and for quasi-Monte Carlo applications. (author´s abstract) / Series: Research Report Series / Department of Statistics and Mathematics

Urban economic theory states that transit improvements result in travel time savings and consequently warrant higher rents particularly with proximity to surrounding stations. This research uses the Sheppard subway corridor as a case study to test the established theories by measuring the changes to residential intensification and property values (1) as a function of time before and after the construction, and (2) as a function of distance to subway stations. Two metrics are established to observe residential intensification and property value: Dwelling Density and Value Density respectively. Dwelling Density is the number of dwellings contained in its property parcel divided by property area; Value Density is total property value of a given property parcel divided by its property area. Using obtained property sales data in four identified analysis years (1991, 1996, 2001, and 2006) and ArcGIS, spatial interpolation surfaces are generated to visualize the changes on a geographical plane through time. Dwelling and Value Density scatterplots are generated by extracting values from the interpolated surfaces and computing its distance to the nearest subway station and to major development nodes. The generated interpolated surfaces show a strong increase in Dwelling and Value Density in North York Centre which suggest that (1) planning policies succeeded in guiding residential growth, (2) a time lag is present of which the full benefits of rapid transit construction are realized, and (3) there may be positive network effects associated with the completion of the Sheppard subway. The scatterplot results demonstrated moderate change in Dwelling and Value Density at the Bayview station area and little change for the remaining stations (Bessarion, Don Mills, and Leslie) based on observations up to December 2006. The results warrant a degree of optimism about Sheppard subway’s ability to attract residential intensification and raise property values, especially given that data was analyzed only up to four years after the subway corridor began revenue service. It is recommended that a similar methodology be performed at a later date when the corridor’s ridership and surrounding development reaches maturity. A preliminary forecasting exercise determined that Dwelling and Value Density will rise, particularly surrounding stations that have since demonstrated little change in residential land use.

When systems designers are making decisions about which components or technologies to select for a design, they often use experience or intuition to select one technology over another. Additionally, developers of new technologies rarely provide more information about their inventions than discrete data points attained in testing, usually in a laboratory. This makes it difficult for system designers to select newer technologies in favor of proven ones. They lack the knowledge about these new technologies to consider them equally with existing technologies. Prior research suggests that set-based design representations can be useful for facilitating collaboration among engineers in a design project, both within and across organizational boundaries. However, existing set-based methods are limited in terms of how the sets are constructed and in terms of the representational capability of the sets. The goal of this research is to introduce and demonstrate new, more general set-based design methods that are effective for characterizing and comparing competing technologies in a utility-based decision framework. To demonstrate the new methods and compare their relative strengths and weaknesses, different technologies for a power plant condenser are compared. The capabilities of different condenser technologies are characterized in terms of sets defined over the space of common condenser attributes (cross sectional area, heat exchange effectiveness, pressure drop, etc.). It is shown that systems designers can use the resulting sets to explore the space of possible condenser designs quickly and effectively. It is expected that this technique will be a useful tool for system designers to evaluate new technologies and compare them to existing ones, while also encouraging the use of new technologies by providing a more accurate representation of their capabilities. I compare four representational methods by measuring the solution accuracy (compared to a more comprehensive optimization procedure's solution), computation time, and scalability (how a model changes with different data sizes). My results demonstrate that a support vector domain description-based method provides the best combination of these traits for this example. When combined with recent research on reducing its computation time, this method becomes even more favorable.

In this thesis a new approach is proposed for non-uniform linear arrays (NLA) which employs conventional subspace methods to improve the direction of arrival (DOA) estimation performance. Uniform linear arrays (ULA) are composed of evenly spaced sensor elements located on a straight line. ULA&#039 / s covariance matrix have a Vandermonde matrix structure, which is required by fast subspace DOA estimation algorithms. NLA differ from ULA only by some missing sensor elements. These missing elements cause some gaps in covariance matrix and Vandermonde structure is lost. Therefore fast subspace DOA algorithms can not be applied in this case. Linear programming methods and array interpolation methods can be used to solve this problem. However linear programming is computationally expensive and array interpolation is angular sector dependent and requires the same number of sensor in the virtual array. In this thesis, a covariance matrix augmentation method is developed by using the array interpolation technique and initial DOA estimates. An initial DOA estimate is obtained by Toeplitz completion of the covariance matrix. This initial DOA estimates eliminates the sector dependency and reduces the least square mapping error of array interpolation. A Wiener formulation is developed which allows more sensors in the virtual array than the real array. In addition, it leads to better estimates at low SNR. The new covariance matrix is used in the root-MUSIC algorithm to obtain a better DOA estimate. Several computer simulations are done and it is shown that the proposed approach improves the DOA estimation accuracy significantly compared to the same number of sensor ULA. This approach also increases the number of sources that can be identifed.

In this thesis work, Cyclic Root MUSIC method is integrated with spatial smoothing and interpolation techniques to estimate the direction of arrivals of coherent,cyclostationary signals received via a Uniform Circular Array (UCA). Cyclic Root MUSIC and Conventional Root MUSIC algorithms are compared for various signal scenarios by computer simulations. A cyclostationary process is a random process with probabilistic parameters, such as the autocorrelation function, that vary periodically with time. Most of the man-made communication signals exhibit cyclostationarity due to the periodicity arising from their carrier frequencies, chip rates, baud rates, etc. Cyclic Root MUSIC algorithm exploits the cyclostationarity properties of signals to achieve signal selective direction of arrival estimation. Spatial smoothing is presented to overcome the coherent signals problem in a multipath propagation environment. Forward spatial smoothing and forward backward spatial smoothing techniques are investigated. Interpolation method is presented to cope with the restrictions of spatial smoothing on array structure. Although the array structure that is considered in this thesis (Uniform Circular Array), is not suitable for applying spatial smoothing directly, using interpolation method makes it possible. Performance of Cyclic Root MUSIC and Conventional Root MUSIC algorithms are compared under variation of various factors by computer simulations. Effects of signal type on the performance of the algorithms are observed by using different signal scenarios.