Walking and bicycling to work, active commuting, can contribute to sustainable mobility and provide regular health-enhancing physical activity for individuals. Our knowledge of active commuting behaviours in general and in different mode and gender groups in particular is limited. Moreover, the validity and reproducibility of the methods to measure the key variables of the behaviours are uncertain. The aims of this thesis is to explore gender and mode choice differences in commuting behaviours in terms of distance, duration, velocity and trip frequency, of a group of adult commuters in Greater Stockholm, Sweden, and furthermore to develop a criterion method for distance measurements and to assess the validity of four other distance measurement methods. We used one sample of active commuters recruited by advertisements, n = 1872, and one street-recruited sample, n = 140. Participants received a questionnaire and a map to draw their commuting route on. The main findings of the thesis were, firstly, that the map-based method could function as a criterion method for active commuting distance measurements and, secondly, that four assessed distance measurement methods – straight-line distance, GIS, GPS and self-report – differed significantly from the criterion method. Therefore, we recommend the use of correction factors to compensate for the systematic over- and underestimations. We also found three distinctly different modality groups in both men and women with different behaviours in commuting distance, duration and trip frequency. These groups were commuters who exclusively walk or bicycle the whole way to work, and dual mode commuters who switch between walking and cycling. These mode groups accrued different amounts of activity time for commuting. Through active commuting per se, the median pedestrian and dual mode commuters met or were close to the recommended physical activity level of 150 minutes per week during most months of the year, whereas the single mode cyclists did so only during the summer half of the year.

Diss. (sammanfattning) Göteborg : Göteborgs universitet, 2007. / Härtill 4 uppsatser.

Diss. (sammanfattning) Luleå : Luleå tekniska univ., 2004. / Härtill 5 uppsatser.

Thesis (M.S.); Submitted to the Univ. of Texas A and M, College Station, TX (US); 4 Oct 2004. / Published through the Information Bridge: DOE Scientific and Technical Information. "UCRL-TH-208163" Schilling, O; Mueschke, N J. 10/04/2004. Report is also available in paper and microfiche from NTIS.

Thesis (M.S. )--University of Tennessee Health Science Center, 1999 / Title from title page screen (viewed on July 16, 2008). Research advisor: Eugene C. Eckstein. Document formatted into pages (91 p. : ill.). Vita. Abstract. Includes bibliographical references (p. 73-77).

Thesis (Ph. D.)--University of Chicago, Dept. of Economics, August 1997. / Includes bibliographical references. Also available on the Internet.

Thesis (doctoral)--Rijksuniversiteit te Utrecht.

Στην παρούσα διατριβή γίνεται διερεύνηση της ικανότητας υπολογισμού της τοπικής ταχύτητας ροής με την χρήση εκκρεμούς, βυθισμένο εντός της ροής. / In this thesis is examined if the local flow velocity can be calculated by a pendulum, with a narrow margin of error.

While many studies have been conducted in channels that are fully open or entirely covered with ice, little has been examined in channels with border ice. To begin filling in this gap in knowledge, experiments were conducted in the Hydraulics Research Testing Facility at the University of Manitoba in a 1.2m wide, 14m long flume to assess the impact of Froude number, coverage ratio and bed-to-ice roughness ratio on the hydraulic characteristics of channels with border ice cover. Acoustic Doppler velocimetry was used to collect detailed 3D velocity data over a cross section of the flume which facilitated the analysis of velocity and turbulence intensity fields as well as the shear stress distribution. The data collected thus far represents the most complete experimental dataset of measured water velocities in a channel with a border ice cover. / February 2016

Made available in DSpace on 2014-06-11T19:30:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2006Bitstream added on 2014-06-13T19:40:16Z : No. of bitstreams: 1 barbosa_rl_dr_prud.pdf: 1353454 bytes, checksum: 109a85af0d056d18c721a2c6af70ce93 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Em certas condições, os sensores de orientação e posicionamento (INS e GPS) de um Sistema Móvel de Mapeamento Terrestre (SMMT) ficam indisponíveis por algum intervalo de tempo casionando a perda da orientação e do posicionamento das imagens capturadas neste intervalo. Neste trabalho, é proposta uma solução baseada apenas nas imagens sem a utilização de sensores ou informações externas às mesmas, através do fluxo óptico. Um sistema móvel com um par de vídeo câmaras, denominado Unidade Móvel de Mapeamento Digital (UMMD), foi utilizado para testar a metodologia proposta em uma via plana. As câmaras são fixadas em uma base com um afastamento entre as câmaras de 0,94m e paralelas ao eixo de deslocamento (Y). A velocidade do veículo é estimada, inicialmente, com base no fluxo óptico denso. Em seguida, a estimação da velocidade é melhorada após uma filtragem, que consiste em: utilizar os vetores que apresentam comportamento radial na metade inferior das imagens e que foram detectados pelo algoritmo de Canny, acrescida uma segunda etapa na estimação da velocidade com eliminação de erros grosseiros. Com a velocidade estimada e sabendo-se o tempo de amostragem do vídeo, o deslocamento de cada imagem é determinado e esta informação é utilizada como aproximação inicial para o posicionamento das câmaras. Os resultados mostraram que a velocidade estimada ficou próxima da velocidade verdadeira e a qualidade do ajustamento se mostrou razoável, considerando-se a não utilização de sensores externos e de pontos de apoio. / Under certain conditions the positioning and orientation sensors such as INS and GPS of a land-based mobile mapping system may fail for a certain time interval. The consequence is that the images captured during this time interval may be misoriented or even may have no orientation. This thesis proposes a solution to orient the images based only on image processing and a photogrammetric technique without any external sensors in order to overcome the lack of external orientation. A land-based mobile mapping system with a pair of video cameras and a GPS receiver was used to test the proposed methodology on an urban flat road. The video cameras were mounted on the roof of the vehicle with both optical axes parallel to the main road axis (Y). The methodology is based on the velocity estimation of the vehicle, which is done in two steps. Initially, the dense optical flow is computed then the velocity estimation is obtained through a filtering strategy that consists of using radial vectors in the low parts of the images. These radial vectors are detected by the Canny algorithm. The vehicle velocity is re-estimated after eliminating the optical flow outliers. With the reestimated velocity and with the video sampling time the spatial displacement of each image (with respect to the previous one of the sequence) is determined. The results show that the estimated velocity is pretty close to the true one and the quality of the least square adjustment is quite acceptable, considering that no external sensors were used.