271 |
Det finns alltid någonting att förbättra : en studie om kroppsuppfattning bland eleverna på designprogrammetÖberg, Anneli January 2007 (has links)
Syftet med denna studie har varit att undersöka hur medier, så som TV, tidningar och Internet påverkar kroppsuppfattningen bland eleverna på designprogrammet. Samt att se om, och i så fall hur, lärarna arbetar med att förebygga den konstlade bild av kropp och kön som media visar upp. Som grund till detta arbete ligger en enkätstudie gjord med 54 elever på ett designprogram. Baserat på resultatet från enkätundersökningen genomfördes gruppintervjuer med lärare och elever på designprogrammets textila inriktning. Resultatet visade att trots att eleverna i väldigt liten utsträckning led av övervikt så eftersträvade de ständigt en slankare och mer vältränad kropp. Vidare framkom att visst påverkades eleverna av medias bild av hur man bör se ut, men att det fanns en ännu större influens, och det var vänner. Slutligen kunde jag konstatera att lärarna i väldigt liten utsträckning arbetade med att förebyga mediers värderingar kring hur kroppen bör se ut.
|
272 |
An examination of zonal mean geopotential variabilityBruce, Leslie Mitchell 09 September 2011 (has links)
A systematic sectoral empirical orthogonal function (EOF) analysis of Southern Hemisphere (SH) extratropical tropospheric zonal-mean geopotential height (GH) is conducted in order to determine how EOF shapes and shape ordering is affected by a decrease in the width of the sector. Previous work (Kushner and Lee 2007) using surface pressure found that the two lead EOFs exchange shape as the sector width decreases below seventy degrees. In the present work, the 500hPa GH field is found to exhibit a similar feature. By fitting a idealized kinematic model, in the form of a Gaussian error function, to daily 500 hPa GH for each sector, the kinematic features of the shape reordering observed in the lead EOFs is shown to arise from the covariance structure of the fluctuating model parameters. The correlations between model parameters which are shown to influence the EOF shapes are further shown to be strongly influenced by statistical properties of daily mass and angular momentum fluctuations. / Graduate
|
273 |
Reflection for subwavelength annular mode in metalsLi, Dan 06 October 2011 (has links)
The coaxial aperture structure has been under intensive study in recent years, particularly
since it exhibits electromagnetic transmission resonances that are stronger
than its circular aperture counterpart. In our work, we study the resonance properties
of a coaxial aperture in a perfect electric conductor (PEC) and in a real metal. For
PEC, The dielectric constant is in finite and for real metal the dielectric constant is fi nite. We develop theory for reflection phase and amplitude in coaxial aperture at the end of a metal plate. While most of the past works of coaxial aperture focused on the propagation of light within the aperture structure and ignore the reflection at end-face,we fi nd that the reflection properties at the end-face are critical to determine both the wavelength and quality of Fabry-Perot resonant transmission of coaxial structure. Finite-di fference time-domain calculations agree well with our theory. We fi rst consider the PEC case, and later to develop the theory to account for real metal
case. In real metal, the phase and amplitude of reflection are quantitatively diff erent from PEC because of plasmonic e ffects. Such di fference arises from the new physics associated with surface plasmons. This work is of interest to ongoing studies of coaxial structures in metal fi lms, which could impact many fields including filter e ffect,optical sensing, optical trapping, near- field spectroscopy and metamaterials. / Graduate
|
274 |
Enhanced high Q whispering gallery resonator sensingYu, Wenyan 22 August 2012 (has links)
This thesis presents a novel method to fabricate metallic nanostructures on whispering gallery mode (WGM) cavity surfaces. The unique properties of WGM cavities have shown their promising future in both fundamental research and engineering applications. High sensitivity biosensors are one of the most important applications. Thanks to their ultra high quality factor (Q) and small optical mode volume, the resonant frequency shift of a single nanoparticle binding becomes detectable. The basic principles of a WGM cavity and its coupling mechanism with an optical coupler are discussed in detail. From the WGM sensing principle, people have demonstrated the positive contributions of the surface plasmon to the sensitivity. Furthermore, we implement the localized surface plasmon resonance (LSPR) on the cavity surface by depositing metallic dots. We use the focused ion beam (FIB) to directly deposit metallic nanodots on the spherical cavity surface for the first time. The quality factor of the cavity with metallic dots is above 10^7 in both air and water, which is more than one order larger than other published results. Also, the new method is much more controllable and repeatable than previous methods. It reveals a new fabrication method for potential ultra sensitive sensors based on WGM cavities.
In addition, we offer a new mode solver for the toroidal WGM cavity. The microtoroid is a better platform for further investigation of WGM sensing than the microsphere. By expanding cavity modes to a set of normal fiber modes, we formulate the new mode solver based on simple physical principles. The simulation results of the radiative quality factor based on the new mode solver are presented as well. / Graduate
|
275 |
Switching control systems and their design via genetic algorithmsChwee, Ng Kim January 1995 (has links)
No description available.
|
276 |
Digital control of high frequency PWM convertorsHolme, Peter R. January 1994 (has links)
The thesis begins with a review of presently available analogue and digital control schemes for high frequency PWM converters. Advantages and disadvantages of each scheme are identified, to determine which features would be desirable in a new digital control scheme. An extensive examination of peak and average current mode control is undertaken, using state-space/sampled data modelling, to gain more detailed information on the properties of current mode control. On the basis of this information, a new digital current mode control scheme is put forward. This uses samples of the inductor current, line voltage and output voltage to implement a control strategy in software. Average inductor current is calculated each switching cycle and compared to the current program level, providing true current mode control. This has some advantages over traditional methods. Accurate inductor current tracking of the current program level is achieved and no slope compensation is required for stable operation over the full range of duty ratios. Line voltage feed-forward is possible in buck derived topologies, which provides an effective null in the audio susceptibility transfer function, independent of compensation parameters. Current loop stability is independent of line voltage or load current in the buck topology, allowing operation with optimum loop compensation under all normal operating conditions. Practical implementation of a digital current mode controlled current-fed converter is described. This includes a modular architecture for the hardware and documentation for the software. Effects of component selection on the achievable converter switching frequency and dynamic performance are discussed. A method is put forward for the direct digital measurement of loop gain and phase in digital control systems. This is used to obtain actual loop responses from a test bed digital current mode controlled current-fed converter. Line and load transient response tests are presented which demonstrate the dynamic characteristics of digital current mode control.
|
277 |
Integrating Transit Pass Ownership into Mode Choice ModellingMcElroy, David P. 22 September 2009 (has links)
The relationship between monthly transit pass ownership and home-work trip mode choice in the Greater Toronto Area was explored using a logit formulation. A Nested Logit model was specified with the primary mode (non-motorised, auto, transit, or auto access to transit) in the upper level and the pass ownership in the lower transit nests. Inclusive value parameters confirm the chosen structure, and a range of policy sensitive, statistically significant parameters having expected signs and magnitudes reveal differences between socio-economic characteristics of pass holders and non-pass holders. In particular, pass holders are less likely to possess a driver’s license or automobile than non-pass holders, implying that passes can be thought of as complementary mobility tools. Cost parameters, which include differentiated pricing for pass and non-pass holders, result in plausible in-vehicle values of time of approximately $31/hour, $33/hour and $8/hour for auto, auto access to transit, and transit all way, respectively.
|
278 |
Integrating Transit Pass Ownership into Mode Choice ModellingMcElroy, David P. 22 September 2009 (has links)
The relationship between monthly transit pass ownership and home-work trip mode choice in the Greater Toronto Area was explored using a logit formulation. A Nested Logit model was specified with the primary mode (non-motorised, auto, transit, or auto access to transit) in the upper level and the pass ownership in the lower transit nests. Inclusive value parameters confirm the chosen structure, and a range of policy sensitive, statistically significant parameters having expected signs and magnitudes reveal differences between socio-economic characteristics of pass holders and non-pass holders. In particular, pass holders are less likely to possess a driver’s license or automobile than non-pass holders, implying that passes can be thought of as complementary mobility tools. Cost parameters, which include differentiated pricing for pass and non-pass holders, result in plausible in-vehicle values of time of approximately $31/hour, $33/hour and $8/hour for auto, auto access to transit, and transit all way, respectively.
|
279 |
The Usability and Learnability of Pen/Tablet Mode InferencingNegulescu, Matei January 2012 (has links)
The inferred mode protocol uses contextual reasoning and local mediators to eliminate
the need to access specic modes to perform draw, select, move and delete operations in a
sketch interface. This thesis describe an observational experiment to understand the learn-
ability, user preference and frequency of use of mode inferencing in a sketch appli- cation.
Novel methodology is presented to study both quantitative and long term qualitative facets
of mode inferencing. The experiment demonstrated that participants instructed in the in-
terface features enjoyed fluid transitions between modes. As well, interaction techniques
were not self-revealing: Participants who were not instructed in interaction techniques took
longer to learn about inferred mode features and were more negative about the interaction
techniques. Over multiple sketching sessions, as users develop expertise with the system,
they combine inferred mode techniques to speed interaction, and frequently make use of
scratch space on the display to retrain themselves and to tune their behaviors. Lastly, post-
task interviews outline impediments to discoverability and how performance is affected by
negative perceptions around computational intelligence. The results of this work inform
the design of sketch interface techniques that incorporate noncommand features.
|
280 |
Investigation of commuting mode choice with respect to TDM policiesZaman, Hamid 06 1900 (has links)
Travel Demand Management (TDM) is now considered one of the most important aspects of transportation planning and operation. The prime objective of TDM is to develop a sustainable transportation system utilizing the existing infrastructure. It is now a well known fact that excessive use of single occupancy vehicle causes numerous problems like traffic congestion, environmental pollution etc. Thus, from TDM perspective, it is of great importance to analyze travel behaviour in order to influence people to reduce car use and choose more sustainable modes such as carpool, public transit, park & ride, walk, bike etc. This study attempts an in-depth analysis of commuting mode choice behaviour using workplace commuter survey data from the City of Edmonton. Unlike traditional mode choice models, this study uses both instrumental and latent variables to better understand the choice process and analyzes their sensitivities with respect to TDM policies. / Transportation Engineering
|
Page generated in 0.0724 seconds