The thesis proposes a mobile app design along with an innovative business plan aiming to encourage sustainable purchasing. To uncover the limitations in current design practices, firstly, represented examples of sustainable design were reviewed. Then, in an attempt to bridge the gap between sustainability and design commercialization, the techniques of persuasion were studied. It is to figure out how to incorporate hot triggers into computational technologies. As an outcome of the study, the final deliverable is a social networking application that provides sustainable product reviews. Instead of following a traditional sustainable design framework, the final deliverable focuses on creating an efficient supply-and-demand circulation for sustainable products. It delivers a unique corporate proposition showing how the system works, gaining modest profits while promoting sustainable development. Based on an online survey and the user study, the value of the proposed idea was validated. Also, the usability and functionality of the app were improved based on participant feedback. / Master of Science

This diploma thesis deals with global illumination and generally with the process of illumination of prepared scenes. A program for illumination management was written for this purpose. It can manage both direct and indirect illumination in interactive time. Simple and comfortable user interface allows for addition, deletion and change in light settings. Different types of both point and area lights are supported. In the course of all work, the program displays current illumination of the scene. With the help of this application, a series of different experiments will be carried out. We will explore the way users work during illumination, the way they perceive different properties of global illumination, various options of its control and its comparison with common direct illumination.

Automatically recognizing gestures of the hand is a promising approach to communicating with computers, particularly when keyboard and mouse interactions are inconvenient, when only a brief interaction is necessary, or when a command involves a three-dimensional, spatial component. Which gestures are most convenient or preferred in various circumstances is unknown. This work explores the idea that perceived physical effort of a hand gesture influences users’ preference for using it when communicating with a computer. First, the hypothesis that people prefer gestures with less effort is tested by measuring the perceived effort and appeal of simple gestures. The results demonstrate that gestures perceived as less effortful are more likely to be accepted and preferred. The second experiment tests similar hypothesis with three-dimensional selection tasks. Participants used the tapping gesture to select among 16 targets in two environments that differ primarily in the physical distance required to finish the task. Participants, again, favor the less effortful environment over the other. Together the experiments suggest that effort is an important factor in user preference for gestures. The effort-to-reliability tradeoff existing in the majority of current gesture interfaces is then studied in experiment 3. Participants are presented 10 different levels of effort-to-reliability tradeoff and decide which tradeoff they prefer. Extreme conditions were intentionally avoided. On average they rate their preferred condition 4.23 in a 10-point scale in terms of perceived effort, and can achieve a success rate of approximately 70%. Finally, the question of whether pointing to objects enhances recall of their visuospatial position in a three-dimensional virtual environment is explored. The results show that pointing actually decreases memory relative to passively viewing. All in all, this work suggests that effort is an important factor, and there is an optimal balance for the effort-to-reliability tradeoff from a user’s perspective. The understanding and careful consideration of this point can help make future gesture interfaces more usable.

Multi-display environments (such as the pairing of a digital tabletop computer with a set of handheld tablet computers) can support collocated interaction in groups by providing individuals with private workspaces that can be used alongside shared interaction surfaces. However, such a configuration necessitates the inclusion of intuitive and seamless interactions to move digital objects between displays. While existing research has suggested numerous methods to bridge devices in this manner, these methods often require highly specialized equipment and are seldom examined using real-world tasks. This thesis investigates the use of two cross-device object transfer methods as adapted for use with commonly-available hardware and applied for use in a realistic task, a familiar tabletop card game. A digital tabletop and tablet implementation of the tabletop card game Dominion is developed to support each of the two cross-device object transfer methods (as well as two different turn-taking methods to support user identification). An observational user study is then performed to examine the effect of the transfer methods on groups’ behaviour, examining player preferences and the strategies which players applied to pursue their varied goals within the game. The study reveals that players’ choices and use of the methods is shaped greatly by the way in which each player personally defines the Dominion task, not simply by the objectives outlined in its rulebook. Design considerations for the design of cross-device object transfer methods and lessons-learned for system and experimental design as applied to the gaming domain are also offered.

Context information brings new opportunities for efficient and effective applications and services on mobile devices. Many existing work exploit the context dependency of mobile usage for specific applications, and show significant, quantified, performance gains by utilizing context. In order to be practical, such works often pay careful attention to the energy and processing costs of context awareness while attempting to maintain reasonable accuracy. These works also have to deal with the challenges of multiple sources of context, which can lead to a sparse training data set. Even with the abundance of such work, quantifying context-dependency and the relationship between context-dependency and performance achievements remains an open problem, and solutions to manage the and challenges of context awareness remain ad-hoc. To this end, this dissertation methodologically quantifies and measures the context dependency of three principal types of mobile usage in a methodological, application agnostic yet practical manner. The three usages are the websites the user visits, the phone numbers they call, and the apps they use, either built-in or obtained by the user from the App Store . While this dissertation measures the context dependency of these three principal types of mobile usage, its methodology can be readily extended to other context-dependent mobile usage and system resources. This dissertation further presents SmartContext, a framework to systematically optimize the energy cost of context awareness by selecting among different context sources, while satisfying the system designer’s cost-accuracy tradeoffs. Finally, this thesis investigates the collective effect of social context on mobile usage, by separating and comparing LiveLab users based on their socioeconomic groups. The analysis and findings are based on usage and context traces collected in real-life settings from 24 iPhone users over a period of one year. This dissertation presents findings regarding the context dependency of three principal types of mobile usage; visited websites, phone calls, and app usage. The methodology and lessons presented here can be readily extended to other forms of context and context-dependent usage and resources. They guide the development of context aware systems, and highlight the challenges and expectations regarding the context dependency of mobile usage.

While many users have relatively general information needs, users who are familiar with a certain topic may have more specific or complex information needs. Such users already have some knowledge of a subject and its concepts, and they need to find information on a specific aspect of a certain entity, such as its cause, effect, and relationships between entities. To successfully resolve this kind of complex information needs, in our study, we investigated the effectiveness of topic-independent query templates as a tool for assisting users in articulating their information needs. A set of query templates, which were written in the form of fill-in-the-blanks was designed to represent general semantic relationships between concepts, such as cause-effect and problem-solution. To conduct the research, we designed a control interface with a single query textbox and an experimental interface with the query templates. A user study was performed with 30 users. Okapi information retrieval system was used to retrieve documents in response to the users’ queries. The analysis in this paper indicates that while users found the template-based query formulation less easy to use, the queries written using templates performed better than the queries written using the control interface with one query textbox. Our analysis of a group of users and some specific topics demonstrates that the experimental interface tended to help users create more detailed search queries and the users were able to think about different aspects of their complex information needs and fill in many templates. In the future, an interesting research direction would be to tune the templates, adapting them to users’ specific query requests and avoiding showing non-relevant templates to users by automatically selecting related templates from a larger set of templates.

While many users have relatively general information needs, users who are familiar with a certain topic may have more specific or complex information needs. Such users already have some knowledge of a subject and its concepts, and they need to find information on a specific aspect of a certain entity, such as its cause, effect, and relationships between entities. To successfully resolve this kind of complex information needs, in our study, we investigated the effectiveness of topic-independent query templates as a tool for assisting users in articulating their information needs. A set of query templates, which were written in the form of fill-in-the-blanks was designed to represent general semantic relationships between concepts, such as cause-effect and problem-solution. To conduct the research, we designed a control interface with a single query textbox and an experimental interface with the query templates. A user study was performed with 30 users. Okapi information retrieval system was used to retrieve documents in response to the users’ queries. The analysis in this paper indicates that while users found the template-based query formulation less easy to use, the queries written using templates performed better than the queries written using the control interface with one query textbox. Our analysis of a group of users and some specific topics demonstrates that the experimental interface tended to help users create more detailed search queries and the users were able to think about different aspects of their complex information needs and fill in many templates. In the future, an interesting research direction would be to tune the templates, adapting them to users’ specific query requests and avoiding showing non-relevant templates to users by automatically selecting related templates from a larger set of templates.

While many users have relatively general information needs, users who are familiar with a certain topic may have more specific or complex information needs. Such users already have some knowledge of a subject and its concepts, and they need to find information on a specific aspect of a certain entity, such as its cause, effect, and relationships between entities. To successfully resolve this kind of complex information needs, in our study, we investigated the effectiveness of topic-independent query templates as a tool for assisting users in articulating their information needs. A set of query templates, which were written in the form of fill-in-the-blanks was designed to represent general semantic relationships between concepts, such as cause-effect and problem-solution. To conduct the research, we designed a control interface with a single query textbox and an experimental interface with the query templates. A user study was performed with 30 users. Okapi information retrieval system was used to retrieve documents in response to the users’ queries. The analysis in this paper indicates that while users found the template-based query formulation less easy to use, the queries written using templates performed better than the queries written using the control interface with one query textbox. Our analysis of a group of users and some specific topics demonstrates that the experimental interface tended to help users create more detailed search queries and the users were able to think about different aspects of their complex information needs and fill in many templates. In the future, an interesting research direction would be to tune the templates, adapting them to users’ specific query requests and avoiding showing non-relevant templates to users by automatically selecting related templates from a larger set of templates.

While many users have relatively general information needs, users who are familiar with a certain topic may have more specific or complex information needs. Such users already have some knowledge of a subject and its concepts, and they need to find information on a specific aspect of a certain entity, such as its cause, effect, and relationships between entities. To successfully resolve this kind of complex information needs, in our study, we investigated the effectiveness of topic-independent query templates as a tool for assisting users in articulating their information needs. A set of query templates, which were written in the form of fill-in-the-blanks was designed to represent general semantic relationships between concepts, such as cause-effect and problem-solution. To conduct the research, we designed a control interface with a single query textbox and an experimental interface with the query templates. A user study was performed with 30 users. Okapi information retrieval system was used to retrieve documents in response to the users’ queries. The analysis in this paper indicates that while users found the template-based query formulation less easy to use, the queries written using templates performed better than the queries written using the control interface with one query textbox. Our analysis of a group of users and some specific topics demonstrates that the experimental interface tended to help users create more detailed search queries and the users were able to think about different aspects of their complex information needs and fill in many templates. In the future, an interesting research direction would be to tune the templates, adapting them to users’ specific query requests and avoiding showing non-relevant templates to users by automatically selecting related templates from a larger set of templates.

In 2012 the two biggest smartphone application markets - the Google Play store and the Apple App Store - each had close to 700 thousand applications with approximately 2 billion downloads happening every month. The introduction of new features and correction of bugs and security vulnerabilities make it usual for mobile application developers to release new version of an application every month. Combined with the great smartphone popularity, it leads to approximately 400 PB annual traffic generated by app updates in the U.S. wireless networks alone. Being partially transmitted through cellular networks, mobile application updates traffic accounts to up to 20% of the annual cellular traffic in the U.S. This thesis presents delta encoding based techniques that significantly reduce update traffic by transferring only the changes (or patches) between two versions of an application. Such network bandwidth reduction enables savings for smartphone users, mobile operators, and data centers that serve app updates. Two Android application update methods - called DELTA and DELTA++ - were developed, implemented, and evaluated. Both methods use delta encoding to transfer only the changes between application versions. DELTA++ improves on DELTA by exploiting the internal structure of APK packages, which are used to distribute Android applications. The APK file can be seen as a compressed archive of all the files contained in application. The DELTA++ algorithm unpackages APK and computes differences between decompressed application files, which allows it to produce much smaller patches. Our experimental results show that DELTA++ reduces app update size by 77% on average. DELTA++ patches are twice smaller than those produced by the Google Smart Application Update method, which is currently used in the Google Play store. This reduction has a trade-off - increased complexity of generated patches makes patch deployment process more sophisticated. Consequently, more time has to be spent to apply the received patch in smartphone. Such delay can be considered acceptable as application update is a delay-tolerant process and smartphone users do not need an update immediately after its release. In order to estimate how much savings can be achieved with DELTA++, a study of Android smartphone users was conducted. The results show that if DELTA++ is used in Google Play instead of the Google Smart Application Update method, then 32 PB or 1.7% of annual traffic can be saved every year in cellular networks in the U.S. The Apple App Store currently does not use any method based on delta encoding to reduce application updates traffic. Usage of methods similar to DELTA++ in the App Store can further increase the savings up to the 12% of yearly cellular traffic in the U.S., which equals to more than $2 billion cost savings a year.