abstract: There has been a lot of work on the characterization of capacity and achievable rate regions, and rate region outer-bounds for various multi-user channels of interest. Parallel to the developed information theoretic results, practical codes have also been designed for some multi-user channels such as multiple access channels, broadcast channels and relay channels; however, interference channels have not received much attention and only a limited amount of work has been conducted on them. With this motivation, in this dissertation, design of practical and implementable channel codes is studied focusing on multi-user channels with special emphasis on interference channels; in particular, irregular low-density-parity-check codes are exploited for a variety of cases and trellis based codes for short block length designs are performed. Novel code design approaches are first studied for the two-user Gaussian multiple access channel. Exploiting Gaussian mixture approximation, new methods are proposed wherein the optimized codes are shown to improve upon the available designs and off-the-shelf point-to-point codes applied to the multiple access channel scenario. The code design is then examined for the two-user Gaussian interference channel implementing the Han-Kobayashi encoding and decoding strategy. Compared with the point-to-point codes, the newly designed codes consistently offer better performance. Parallel to this work, code design is explored for the discrete memoryless interference channels wherein the channel inputs and outputs are taken from a finite alphabet and it is demonstrated that the designed codes are superior to the single user codes used with time sharing. Finally, the code design principles are also investigated for the two-user Gaussian interference channel employing trellis-based codes with short block lengths for the case of strong and mixed interference levels. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2015

Made available in DSpace on 2014-12-17T14:55:06Z (GMT). No. of bitstreams: 1 RummeniggeRD.pdf: 785767 bytes, checksum: 0bba3130cce258f9fafc7849fe6507ce (MD5) Previous issue date: 2008-02-15 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In this work, we propose the Interperception paradigm, a new approach that includes a set of rules and a software architecture for merge users from different interfaces in the same virtual environment. The system detects the user resources and provide transformations on the data in order to allow its visualization in 3D, 2D and textual (1D) interfaces. This allows any user to connect, access information, and exchange information with other users in a feasible way, without needs of changing hardware or software. As results are presented two virtual environments builded acording this paradigm / Neste trabalho, ? apresentado o paradigma Interperceptivo, uma nova abordagem que inclui um conjunto de regras e uma arquitetura de software que une usu?rios de interfaces diferentes no mesmo ambiente virtual. O sistema detecta os recursos do usu?rio e realiza transforma??es nos dados para sua visualiza??o nas interfaces 3D, 2D e textual (1D). Isto permite que qualquer usu?rio conecte, acesse todas as informa??es, e troque informa??es com os outros usu?rios de um modo flex?vel, sem necessitar de altera??es no hardware e sofware. Como resultados s?o apresentados dois ambientes virtuais constru?dos segundo este paradigma

The use of computers has grown immensely in the last decades and the possibility to teach through them has grown as well. Various computer applications, games and forums have been created as tools of teaching and learning. This research project contains a summary of various works created within the E-learning area and their results. The virtual world Second Life is tested and some of the research in the literature review will be visited and examined. The research focuses on the feasibility to create scenarios for nursing students to practice patient care and handling, in addition to collaborative qualities that online virtual worlds offer. The conclusion taken from this research is that the possibilities far outweigh the limitations and that learning through virtual worlds should be further explored and developed.

Virtual Reality provides the ability to immerse users in realistic environments, which makes it possible to utilize the technology as an educational tool. The EIT Raw Materials Project MireBooks intend to teach mining students by simulating a VR mine and recreating learning experiences in it. With this comes challenges with regards to the networking performance and user experience. / MiReBooks

Undo is a command that users rely on in most software applications. Its importance in multi-user CAD is no different. However, due to its unique nature, users may have different expectations regarding how undo should behave. This research seeks to better understand users' expectations regarding undo in multi-user CAD by having users participate in collaborative design exercises and then asking them how they would expect undo to behave. In addition, users participated in a survey in which they watched 8 videos showing users interacting within multi-user CAD and were then asked about how they would want undo to behave. Based on these findings, various recommendations are made for how undo ought to be implemented in multi-user CAD. These include recommendations regarding the user experience/user interface as well as proposing an equation that seeks to quantify whether a user expects to share an undo stack with another user or if they should only be able to undo their own actions.

京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第20741号 / 情博第655号 / 新制||情||113(附属図書館) / 京都大学大学院情報学研究科通信情報システム専攻 / (主査)教授 原田 博司, 教授 守倉 正博, 教授 大木 英司 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

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The NSF Center for e-Design, Brigham Young University (BYU) site has re-architected Computer Aided Design (CAD) tools, enabling multiple users to concurrently create, modify and view the same CAD part or assembly. This technology allows engineers, designers and manufacturing personnel to simultaneously contribute to the design of a part or assembly in real time,enabling parallel work environments within the CAD system. Multi-user systems are only as robust and efficient as their methods for managing conflicts and preserving model consistency. Conflicts occur in multi-user CAD when multiple users interoperate with the same or dependent geometry. Some conflicts can lead to model inconsistencies which means that each user's instance of the model are not identical. Other conflicts cause redundant work or waste in the design process. This dissertation presents methods to avoid and resolve conflicts which lead to model inconsistency and waste in the design process. The automated feature reservation method is presented which prevents multiple users from simultaneously editing the same feature, thus avoiding conflicts. In addition, a method is also presented which ensures that copies of the model stay consistent between distributed CAD clients by enforcing modeling operations to occur in the same order on all the clients. In cases of conflict, the conflicting operations are preserved locally for manual resolution by the user. An efficient model consistency method is presented which provides consistent references to the topological entities in a CAD model, ensuring operations are applied consistently on all models. An integrated task management system is also presented which avoids conflicts related to varying user design intent. Implementations and results of each method are presented. Results show that the methods effectively manage conflicts and ensure model consistency, thus providing a solution for a robust multi-user CAD system.

This thesis presents a new method that improves upon the existing approaches to developing collaborative tools. The new method uses automatically inferred and manually recorded design rationale to intelligently filter the information that is shared by a collaborative tool. This represents an improvement upon the existing state of the art in collaborative engineering tools. To demonstrate the viability of the method three collaborative tools were created. The first is a multi-user collaborative design environment tool named SimulPart and built upon the NX CAD package. SimulPart uses the new method to limit the amount of communication required to keep every user in synch during a multi-user co-design session. The second implementation is a visual history tool named VisiHistory that allows designers to watch time lapse videos of the creation of a design that are automatically generated using the new method. The final tool is an intelligent user directory named SmartHelp that uses the new method to allow designers to identify which of their peers have expertise in certain CAD operations. Validation was performed for each of these tools by benchmarking the tool against the leading commercial solution or industry process. The results of the validation showed that the new method does in fact offer a superior collaborative solution as it outperforms the existing tools and methods in several key collaborative metrics. As a result of this work future efforts are encouraged into both improving upon the quality of the inferred design rationale and increasing the functionality of the three tools created using the new method.

An industry survey was conducted to collect information on current collaboration methods and project management and communication structures. The results, along with other design collaboration philosophies, were used to develop a method of coordinating users in a multi-user design space. These thesis methods will regulate collaboration and avoid user collisions in the same model space, either by cooperative interaction or by spatial decomposition with regional blocking. The method partitions the design space by integrating a graphical user interface tool into the engineering application used to define and assign the necessary tasks of the project. A simple implementation of this method proved that it is usable by multiple users, is faster to setup than simple written instructions, and helps to coordinate users to work together efficiently. To enable some of the key capabilities of the method, modern Computer-Aided application (CAx) architecture would need to be revised with multiple users in mind. One constraint example would be to partition the design space geometrically with visible boundaries between user-assigned areas. Current CAx architectures have some selection filtering capability that can be based on mathematical constraint boundaries, but are not designed to globally filter selection and are not very useful in their limited form. A simple solution to working around this limitation has not been found.