Andersen T.M.,Technical University of Denmark |
Christensen S.K.,Bang and Olufsen |
Knott A.,Technical University of Denmark |
Andersen M.A.E.,Technical University of Denmark
Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC | Year: 2011
This paper describes the analysis and design of a DC-DC converter topology which is operational at frequencies in the Very High Frequency (VHF) band ranging from 30 MHz-300 MHz. The presented topology, which consists of a class E inverter, class E rectifier, and self-oscillating gate driver, is inherently resonant, and switching losses are greatly reduced by ensuring Zero Voltage Switching (ZVS) of the power semiconductor devices. A design method to ensure ZVS operation when combining the inverter, rectifier, and gate driver is provided. Several parasitic effects and their influence on converter operation are discussed, and measurement results of a 100 MHz prototype converter are presented and evaluated. The designed prototype converter verifies the described topology. © 2011 IEEE.
Francombe J.,University of Surrey |
Mason R.,University of Surrey |
Dewhirst M.,University of Surrey |
Bech S.,Bang and Olufsen
132nd Audio Engineering Society Convention 2012 | Year: 2012
An experiment was performed in order to establish the threshold of acceptability for an interfering audio programme on a target audio programme, varying the following physical parameters: target programme, interferer programme, interferer location, interferer spectrum, and road noise level. Factors were varied in three levels in a Box-Behnken fractional factorial design. The experiment was performed in three scenarios: information gathering, entertainment, and reading/working. Nine listeners performed a method of adjustment task to determine the threshold values. Produced thresholds were similar in the information and entertainment scenarios, however there were significant differences between subjects, and factor levels also had a significant effect: interferer programme was the most important factor across the three scenarios, whilst interferer location was the least important.
Luan Y.,Bang and Olufsen |
Luan Y.,Technical University of Denmark |
Ohlrich M.,Technical University of Denmark |
Jacobsen F.,Technical University of Denmark
Journal of Sound and Vibration | Year: 2011
New developments in the simplified smearing technique for modeling vibrations of cross-stiffened, thin rectangular plates are presented. The computationally efficient smearing technique has been known for many years, but so far the accuracy of, say, predicted natural frequencies has been inadequate. The reason is that only the stiffeners at a right angle to the axis of angular motion are taken into account when calculating the bending stiffness, whereas the stiffeners that are parallel to this axis of angular motion are neglected. To improve predictions, the parallel stiffeners are taken into account in this paper. The improved smearing technique results in better accuracy for predicted natural frequencies of flat stiffened plates, as demonstrated for both simply supported and clamped boundary conditions. The improved prediction accuracy is demonstrated by comparing results from a numerical model based on the current development with results from finite element (FE) simulations that include the exact cross-sectional geometries of the stiffened panel. In order to demonstrate applications of the improved smearing technique, the predicted forced response is compared with both experimental and FE results. Another improvement concerns the orientation of the stiffeners. The original smearing technique presupposes that the stiffeners are parallel to the edges of the plate, but simple considerations make it possible to relax this requirement. To test the validity of the resulting technique a series of plates are examined for stiffeners angled relative to the plate edges. © 2011 Elsevier Ltd.
Korhonen J.,Technology University of Denmark |
Burini N.,Technology University of Denmark |
Forchhammer S.,Technology University of Denmark |
Pedersen J.M.,Bang and Olufsen
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011
Traditionally, algorithm-based (objective) image and video quality assessment methods operate with the numerical presentation of the signal, and they do not take the characteristics of the actual output device into account. This is a reasonable approach, when quality assessment is needed for evaluating the signal quality distortion related directly to digital signal processing, such as compression. However, the physical characteristics of the display device also pose a significant impact on the overall perception. In order to facilitate image quality assessment on modern liquid crystaldisplays (LCD) using light emitting diode (LED) backlight with local dimming, we present the essential considerations and guidelines for modeling the characteristics of displays with high dynamic range (HDR) and locally adjustable backlight segments. The representation of the image generated by the model can be assessed using the traditional objective metrics, and therefore the proposed approach is useful for assessing the performance of different backlight dimming algorithms in terms of resulting quality and power consumption in a simulated environment. We have implemented the proposed model in C++ and compared the visual results produced by the model against respective images displayed on a real display with locally controlled backlight units. © 2010 Copyright SPIE - The International Society for Optical Engineering.
Mortensen D.H.,Bang and Olufsen |
Mortensen D.H.,University of Aarhus
UbiComp'10 - Proceedings of the 2010 ACM Conference on Ubiquitous Computing | Year: 2010
This poster abstract presents the first part of a study concerning the use of information about gaze, grip and gesture to create non-command interaction. The experiment reported here seeks to establish the occurrence of patterns in nonverbal communication, which may be used in an activity aware setup that seeks to adjust to the individual's intentions and attention. Results indicate that basic patterns of facial direction and grip are correlated with intention and/or attention, and an analysis of gesture patterns is currently being performed. © 2010 Copyright is held by the author/owner(s).