Frictional Fluid Dynamics and Plug Formation in Multiphase Millifluidic Flow

We study experimentally the flow and patterning of a granular suspension displaced by air inside a narrow tube. The invading air-liquid interface accumulates a plug of granular material that clogs the tube due to friction with the confining walls. The gas percolates through the static plug once the gas pressure exceeds the pore capillary entry pressure of the packed grains, and a moving accumulation front is reestablished at the far side of the plug. The process repeats, such that the advancing interface leaves a trail of plugs in its wake. Further, we show that the system undergoes a fluidization transition—and complete evacuation of the granular suspension—when the liquid withdrawal rate increases beyond a critical value. An analytical model of the stability condition for the granular accumulation predicts the flow regime

A Configurable Photo Browser Framework for Large Image Collections

Image collections are growing at an exponential rate due to the wide availability of inexpensive digital cameras and storage. Current browsers organize photos mostly chronologically, or according to manual tags. For very large collections acquired over several years it can be difficult to locate a particular set of images – even for the owner. Although our visual memory is powerful, it is not always easy to recall all of one’s images. Moreover, it can be very time consuming to find particular images in other peoples image collections. This paper presents a prototype image browser and a plug-in pattern that allows classifiers to be implemented and easily integrated with the image browser such that the user can control the characteristics of the images that are browsed and irrelevant photos are filtered out. The filters can both be content based and based on meta-information. The current version is only employs meta-information which means that large image collections can be indexed efficiently

An Energy Efficient Localization Strategy for Outdoor Objects based on Intelligent Light-Intensity Sampling

A simple and low cost strategy for implementing pervasive objects that identify and track their own geographical location is proposed. The strategy, which is not reliant on any GIS infrastructure such as GPS, is realized using an electronic artifact with a built in clock, a light sensor, or low-cost digital camera, persistent storage such as flash and sufficient computational circuitry to make elementary trigonometric computations. The object monitors the lighting conditions and thereby detects and tracks the sunrise and sunset times. By the means of a simple celestial model an estimate of the geographical position of the object can be made. An intelligent light sampling method is proposed allowing the object to sleep most of the time and hence save battery power. The strategy is energy efficient and the speed of convergence can be adjusted as a function of the energy consumed. Objects employing the method can therefore operate for long times without recharging their batteries. The strategy has applications in mobile sensor networks where nodes need to log geographical information, sensing equipment such as floating buoyancies, or pervasive technologies in need of geo-spatial information such as digital cameras, mobile devices, etc

On the Truthfulness of Petal Graphs for Visualisation of Data

A petal graph is an aesthetically attractive and applauded tool for visualising parameter sets. For instance, petal graphs are often used by Norwegian policy makers and decision makers in higher education as the Ministry of Education and Research relies on petal graphs in their reports. This study argues that petal graphs are prone to misinterpretation. It is challenging to interpret a petal graph in general, it is hard to compare two or more petal graphs and this study demonstrates that the physical characteristics of petal graphs can be incorrect in terms of the parameters on display. This study concludes that the use of petal graphs should be abolished and that other visualisation techniques to be used instead. Several alternatives are suggested

Determining the Geographical Location of Image Scenes based on Object Shadow Lengths

Many studies have addressed various applications of geo-spatial image tagging such as image retrieval, image organisation and browsing. Geo-spatial image tagging can be done manually or automatically with GPS enabled cameras that allow the current position of the photographer to be incorporated into the meta-data of an image. However, current GPS-equipment needs certain time to lock onto navigation satellites and these are therefore not suitable for spontaneous photography. Moreover, GPS units are still costly, energy hungry and not common in most digital cameras on sale. This study explores the potential of, and limitations associated with, extracting geo-spatial information from the image contents. The elevation of the sun is estimated indirectly from the contents of image collections by measuring the relative length of objects and their shadows in image scenes. The observed sun elevation and the creation time of the image is input into a celestial model to estimate the approximate geographical location of the photographer. The strategy is demonstrated on a set of manually measured photographs

Value creation in private equity : have Norwegian private equity companies created value in their portfolio companies?

This paper investigates value creation in 31 private equity-owned companies in Norway between 1993 and 2007. Its purpose is to find evidence on increased value capturing for these companies relative to non-private equity-owned companies. We have looked at the development of companies that have been engaged in a full leveraged buyout process with Norwegian private equity firms from entry to exit. Value creation is made through several different drivers, which are thoroughly presented in this thesis. The empirical analysis in our thesis has been focusing on value creation through direct drivers since these drivers may easily be analyzed using publicly available data. By doing statistical tests on ratios that help explaining these drivers, we were able to present evidence on whether private equity-owned companies have been able to outperform their comparables during the private equity firms’ holding period. Our results suggest that private equity firms have been successful in obtaining significant revenue expansion and cost reductions/margin improvements for their portfolio companies on an isolated basis. In terms of improved asset utilization and financial engineering we are unable to provide any adequate significant results. In addition, it seems like buyout companies do not experience any significant changes in employment or changes in levels of wage expenditures. The industry-adjusted results suggest that buyout companies do not significantly outperform their corresponding peers in regard to revenue expansion and cost reductions/margin improvements. Buyout companies seem to have a somewhat stronger improvement in capital productivity than their peers, implying an outperformance from the buyout companies. Moreover, our results do not support any significant changes in long-term debt share during the holding period of private equity firms or large differences in long-term debt levels relative to their peers at entry, exit and exit +1. Finally, industry-adjusted employment growth and changes in levels of wage expenditures do not support any categorical beliefs about massive lay-offs or drastically reduced wage expenditures during the holding period of a private equity firm

Towards Accessible Self-service Kiosks through Intelligent User Interfaces

Public self-service kiosks provide key services such as ticket sales, airport check-in and general information. Such kiosks must be universally designed to be used by society at large, irrespective of the individual users’ physical and cognitive abilities, level of education and familiarity with the system. The noble goal of universal accessibility is hard to achieve. This study reports experiences with a universally designed kiosk prototype based on a multimodal intelligent user interface that adapts to the user’s physical characteristics. The user interacts with the system via a tall rectangular touch-sensitive display where the interaction area is adjusted to fit the user’s height. A digital camera is used to measure the user’s approximate reading distance from the display such that the text size can be adjusted accordingly. The user’s touch target accuracy is measured, and the target sizes are increased for users with motor difficulties. A Byzantine visualization technique is employed to exploit unused and unreachable screen real estate to provide the user with additional visual cues. The techniques explored in this study have potential for most public self-service kiosks

On the usefulness of Aaa-links for controlling text size on web pages : preliminary results

Aaa-links, also known as triple-a links, have over the last few years become commonplace on the web. In a move to become more universally accessible organizations have introduced Aaa-links to help users with reduced vision. This study questions this practice. Three related research questions are posed. First, how is text enlargement functionality best represented visually? Second, are these Aaa-inks really making the web-browsing experience more comfortable for users? Third, is it better to use built-in browser text-enlargement functionality? A small user test involving 30 individuals was conducted. The preliminary results suggest that the effectiveness of Aaa-links is overrated