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As the number of information system users increases, we are witnessing a related increase in the complexity and the diversity of their applications. The increasing functional complexity amplifies the degree of functional and technical understanding required of the user to make productive use of the application tools. Emerging technologies, increased and varied user interests and radical changes in the nature of applications give rise to the opportunity and necessity to re-examine the proper apportionment of cognitive responsibilities in human-system interaction. We present a framework for the examination of the allocation of cognitive responsibilities in information systems. These cognitive tasks involve skills associated with the models and tools that are provided by information systems and the domain knowledge and problem knowledge that are associated with the user. The term cognitor is introduced to refer to a cognitive capacity for assuming such responsibilities. These capacities are resident in the human user and they are now feasible in information system architectures. Illustrations are given of how this framework can be used in understanding and assessing the apportionment of responsibilities. Implications of shifting and redistributing cognitive task from the system-user environment to the system environment are discussed. Metrics are provided to assess the degree of change under alternative architectures. An architecture for the design of alternative responsibility allocations, named Reapportionment of Cognitive Activities, (RCA), is presented. The architecture describes knowledge and responsibilities associated with facilitating dynamic allocation of cognitive responsibilities. Knowledge bases are used to support and describe alternative apportionments. RCA illustrates how knowledge representations, search techniques and dialogue management can be combined to accommodate multiple cooperating cognitors, each assuming unique roles, in an effort to share the responsibilities associated with the use of an information system. A design process for responsibility allocation is outlined. Examples of alternative responsibility allocation feasible within this architecture are provided. Cases implementing the architecture are described. We advocate treating the allocation of cognitive responsibilities as a design variable and illustrate through the architecture and the cases the elements necessary in reapportioning these responsibilities in information systems dialogues.

The purpose of this research was to provide evidence to support specific features of a software user interface implementation. A 3 x 2 x 2 full factorial, between subjects design was employed, in a laboratory experiment systematically varying existence or non-existence of a user interface and media of help documentation (either online or written), while blocking for varying levels of user experience. Subjects completed a set of tasks using a computer, so the experimenters could collect and evaluate various performance and attitudinal measures. Several attitudinal measures were developed and validated as part of this research. Consistent with previous findings, this research found that a user's previous level of experience in using a computer had a significant impact on their performance measures. Specifically, increased levels of user experience were associated with reduced time to complete the tasks, fewer number of characters typed, fewer references to help documentation, and fewer requests for human assistance. In addition, increased levels of user experience were generally associated with higher levels of attitudinal measures (general attitude toward computers and satisfaction with their experiment performance). The existence of a user interface had a positive impact on task performance across all levels of user experience. Although experienced users were not more satisfied with the user interface than without it, their performance was better. This contrasts with at least some previous findings that suggest experienced users are more efficient without a menu-driven user interface. The use of online documentation, as opposed to written, had a significant negative impact on task performance. Specifically, users required more time, made more references to the help documentation, and required more human assistance. However, these users generally indicated attitudinal measures (satisfied) that were as high with online as written documentation. There was a strong interaction between the user interface and online documentation for the task performance measures. This research concludes that a set of tasks can be performed in significantly less time when online documentation is facilitated by the presence of a user interface. Written documentation users seemed to perform equivalently with or without the user interface. With online documentation the user interface became crucial to task performance. Research implications are presented for practitioners, designers and researchers.

The main objectives of this dissertation are the following. The first objective is concerned with the stabilization of large-scale systems by a decentralized control. The fundamental idea behind this type of control is the stabilization of the isolated subsystems of a large-scale system in such a way that the global stability requirement is also satisfied. For this purpose, a new stability criterion is introduced to identify a class of interconnected systems that can be stabilized by local state feedback. In addition to this, two specific classes of interconnections are presented for which the overall system stability can be ensured by a decentralized approach. A new constructive procedure for the design of decentralized controllers for the identified classes of large-scale systems is discussed. The principal advantages of this design procedure are that it requires a minimal amount of computation and is a systematic procedure eliminating the trial and error arguments as in the earlier methods. The second objective of the dissertation is to investigate the problem of the stabilization of a class of large-scale systems which are composed of identical subsystems and identical interconnections. For this class of systems, certain significant theorems, concerning the qualitative properties are introduced. Following the guidelines set forth by the above theorems, a few different schemes for the decentralized and multilevel control of the aforementioned class of large-scale interconnected systems are presented. The third objective concerns the development of a few different schemes for the design of an asymptotic state estimator for large-scale systems described as interconnections of several low-order subsystems. The most attractive feature of the present schemes is that the majority of the necessary computations are performed at the subsystem level only, thereby leading to a simple and practicable estimator design. Finally, all the above results are illustrated by numerical examples. Further, a comparison study is conducted to show the advantages of the methods and the results in this dissertation in comparison with some results available in the literature.

The increasing complexity of decision situations has required organizations to integrate more types of expertise and consider more criteria for effective group decision making. Researchers have begun to examine how computer based support in the form of a Group Decision Support System (GDSS) can enhance the process and outcomes of decision making groups. This dissertation investigated the impact of GDSS for strategic planning impact analysis. The GDSS was based on the Stakeholder Identification and Assumption Surfacing Model. A controlled laboratory experiment was used to compare the process and outcomes of 4-person groups which had GDSS support, comparable manual support, and no support. The experimental task was a policy statement requiring undergraduates to have a personal computer for admittance to a business college. Groups were asked to determine a list of the most critical stakeholders who would be impacted by the policy, and their assumptions regarding the policy statement. Measures were taken on decision outcomes (decision quality, decision time, and satisfaction with the outcomes) and decision process variables (quantity of unique alternatives, distribution of individual participation, and satisfaction with the process). Additionally, observational data was recorded through the use of videotape recordings of the sessions. The major findings of the study are: (1) Decision quality is enhanced when groups use a structured methodology; (2) Decision time was shortest in the unstructured groups, with GDSS groups finishing somewhat faster than manual structured groups; (3) Satisfaction with the outcomes was not different between structured and unstructured groups, however it was higher in the GDSS groups compared to the structured manual groups; (4) Quantity of unique alternatives was much higher in the groups using a structured methodology; (5) Distribution of individual participation was more equal in groups using a structured methodology; and (6) Satisfaction with the process was not different between structured and unstructured groups, however the GDSS groups were more satisfied than the structured manual groups.

Current research in screen design for human computer interaction has demonstrated that user task performance is influenced by placement, prompting methodology, and screen complexity. To assess the difference between a grouped item screen prompt and a series of single item screen prompts, a field experiment in a semiconductor manufacturing facility was designed. Subjects were randomly assigned to one of two groups to use a data entry system. Seven of the screen prompts differed between the two groups. During the four weeks of the study, a significant difference was measured between groups. The group screen users had lower task times for all four weeks. No significant correlation exists between work experience, performance review scores, or designated work shift. A strong negative correlation exists between frequency of system usage and task time. No difference was noted for measured errors. Subjective scores significantly favored the group screen design.

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The aim of this thesis is to explore the possibility of integrating an AC3 audio de- coding module into the company’s current product. Due to limited left resources on the FPGA chip in the company’s current product, the focus of this thesis is to be resource efficient. In this thesis, a system for AC3 audio decoding is designed and implemented. In order to use less logic on FPGA, PicoBlaze soft processor is used to control the whole processing flow. The system is designed and synthe- sized for a Spartan-6 FPGA which can be easily ported to the company’s current platform.

Interference is one of the most common causes of performance issues and reliability issues in wireless networks. Interference and background noise can be localized by performing spectrum analysis to measure amplitude and frequency characteristics of electromagnetic signals. Initially a theoretical description of spectrum analysis and site survey was performed. Manual spectrum analysis was also examined by performing practical measurements and creating graphs with Metageek Wi-Spy and Chanalyzer. Signals from 802.11 units were observed with spectrum analysis, and were analyzed according to their visual interference levels. This was compared to the actual interference impact of the units. This analysis showed that manual spectrum analysis could be hard to interpret when it comes to interference, as signals from units that looked harmful were in fact not. The channel access method of the units, in this case CSMA/CA, contributed to a low impact of interference, since the units waited for the medium to be free before sending, which reduced the probability of collisions. Cisco CleanAir technology has built-in spectrum analysis functionality, to detect, classify and avoid radio frequency interference. Dynamic interference detection and avoidance reduces costs in operating and network outages. This is made possible by Cisco Radio Resource Management (RRM) - a system consisting of multiple protocols that can dynamically change frequency channel and power. The protocols of RRM were examined and discussed relative to the lab measurement. The measurements showed that the Cisco Aironet 2700 access point was more robust against interference compared to a D-Link router for small offices and home use. The robustness of an access point depends on its wireless standard, modulation and dynamic management protocols. Wireless communication is a complex subject, where multiple factors has an impact on network performance. Therefore, it might not be appropriate to draw any hard conclusions from the laboratory measurements that were performed. For future studies, similar lab measurements should be carried out by creating interference from non-802.11 units to compare the interference impact from CSMA and non-CSMA communication. / Störningar är en av de vanligaste orsakerna till försämrad prestanda och tillförlitlighet i trådlösa nätverk. Frekvensstörningar och brus kan lokaliseras genom att utföra spektrumanalys för att mäta amplitud- och frekvensegenskaper hos elektromagnetiska signaler. Inledningsvis gjordes en teoretisk beskrivning av spektrumanalys och site survey. Manuell spektrumanalys undersöktes dessutom praktiskt genom laborationsmätningar och grafritning med Metageek Wi-Spy och dess mjukvara Chanalyzer. Signaler från 802.11-enheter betraktades med spektrumanalys, och analyserades utifrån hur störande dess signaler såg ut att vara. Detta jämfördes sedan mot den faktiska störningsinverkan enheterna hade. Analysen visade att manuellt genomförd spektrumanalys kan vara svårtolkad när det kommer till att identifiera störande moment, då signaler från enheter som såg ut att störa mycket i själva verket inte gjorde det. Enheternas kanalaccessmetod, i det här fallet CSMA/CA, bidrog till en låg störningsinverkan då enheterna väntade med att sända tills mediet var ledigt, vilket minskade risken för kollisioner. Ciscos nya CleanAir-teknologi har inbyggd spektrumanalysfunktionalitet, för att kunna upptäcka, klassificera och undvika radiofrekvensstörningar. Att störningar automatiskt kan upptäckas och åtgärdas sparar både driftskostnader och minimerar nätverksavbrott. Denna automatisering är möjlig tack vare Cisco Radio Resource Management (RRM) som är ett system bestående av flera protokoll, och innefattar bland annat funktioner för att byta kanal och ändra utsänd effekt automatiskt. De protokoll som ingår i RRM undersöktes och diskuterades sedan i förhållande till genomförda laborationsmätningar. Laborationsmätningar visade att Ciscos Aironet 2700-accesspunkt var mer robust mot störningar än en D-Link-router avsedd för hemmabruk och mindre kontorsmiljöer. En accesspunkts robusthet avgörs av dess trådlösa standard, modulationsteknik och dynamiska managementprotokoll. Trådlös kommunikation är ett komplext ämne, där många faktorer har betydelse för ett nätverks prestanda. Det är därför inte lämpligt att dra några konkreta slutsatser från de laborationsmätningar som genomfördes. För framtida arbeten bör liknande laborationer med störningar från icke-802.11-enheter genomföras för att jämföra störningsinverkan från CSMA- och icke-CSMA-kommunikation.