The open-end winding machines can be fed by two three-phase inverters. In each phase, three-level voltages are generated by an H-bridge. Three-level PWM can reduce current ripple in α-β frame by using the voltage vectors on the vertices of small triangle. For open-end winding configuration, PWM methods which use the small triangle have been implemented with space vector modulation based techniques. These techniques modulate the voltage by switching one inverter while clamping the other inverter. To distribute switching stress, the role of switching and clamping are alternated between the two inverters based on the area in α-β frame. However, the switching stress is still concentrated to one inverter in low speed because the role change depends on the electrical angle. In this paper, a PWM method which uses the small triangle without clamping the output of inverters is proposed. The method is implemented with carrier based technique. It is realized by alternating two carrier waves which have 90° phase difference depending on the polarity of the reference voltage. The experimental results show that the proposed method can reduce the α-β current ripple as well as the conventional method with clamping.

In this paper, high bandwidth current control for an open-end winding induction motor is realized with deadbeat control. A deadbeat current controller achieves higher gain than a PI current controller by compensating for the error caused by the digital sampling delay. The response of a deadbeat controller is directly influenced by its sampling frequency, while that of PI controller depends on gain tuning. In this paper, a quarter carrier period sampling of current controller is proposed for control of an open-end winding induction motor. In the proposed method, the sampling frequency is doubled as compared with the conventional half carrier period sampling method. Thus, the frequency response of the deadbeat current control is improved with this quarter carrier period sampling. The validity of this high bandwidth current controller is verified by simulation.

Studies have shown that programmers frequently seek external information during programming, from source code and documents, as well as from other programmers because much of the information remains in the heads of programmers. Programmers therefore often ask other programmers questions to seek information in a timely fashion to carry out their work. This information seeking entails several conflicting factors. From the perspective of the information-seeking programmer, not asking questions degrades productivity. Conversely, asking questions interrupts other programmers and degrades their productivity, and may be frowned upon by peers due to the perceived social inconsideration of the information seeker. From the perspective of the recipients of the question, even though helping is costly, not helping also incurs social costs due to the deviation from social norms. To balance all these factors, this paper proposes the STeP_IN (Socio-Technical Platform for In situ Networking) framework to guide the design of systems that support information seeking during different phases of programming. The framework facilitates access to the information in the heads of other programmers while minimizing the negative impacts on the overall productivity of the team.

This paper describes a system called STeP/spl I.bar/IN (standing for socio-technical platform for in situ networking) that assists software developer to find and learn Java API libraries. It provides individualized search interface for Java developers, examples that illustrate the usage, and more distinctively a facilitating mechanism that connects Java developers to exchange expertise based on their expertise and social relations. STeP/spl I.bar/IN is designed and developed based on the dynamic community theory, a new collaboration form that we have proposed.

Software development is a knowledge intensive activity and software developers are knowledge workers. Knowledge needed for software development is often distributed among different developers. Supporting efficient knowledge collaboration and transfer is thus essential for software development organizations to remain competitive. This paper proposes a new theory /sub y/namic community to support knowledge collaboration and discusses its application in software development. Dynamic community integrates the traditional knowledge management approach in which knowledge is formalized and accumulated in knowledge repositories, and the community-based knowledge collaboration approach in which knowledge is transferred through informal community participation and human contacts. The dynamic community theory takes into full consideration individual knowledge workers' ever-changing needs for new knowledge as well as the role of social relationship of knowledge workers in effective knowledge collaboration. This paper introduces the dynamic community theory, a general system architecture of sociotechnical environments in support of dynamic community, and its application in software development.

The complexity of many problems necessitates creating and exploring multiple, alternative solutions. However, current user interfaces do not cleanly support creating alternatives at a time when they are likely to be discovered: as users interactively modify data. This paper presents Parallel Paths, a novel model of interaction that facilitates generating, manipulating, and comparing alternative solutions. In contrast to existing approaches such as automated history capture tools, Parallel Paths emphasizes the active, simultaneous development of multiple, alternative solutions. We demonstrate this model of interaction in Parallel Pies, a user interface mechanism developed for image manipulation tasks that allows users to: easily create solution alternatives as they interact with a command; embed the alternatives in the same workspace; manipulate the alternatives independently or simultaneously as if they were the same object; and perform side-by-side comparisons of each. Results from an initial evaluation are presented, along with implications for future designs.

We have developed a series of tools, which use spatial positioning of objects as a means of externalizations in designing linear information. They include a tool for collage-style writing, a tool for notes summarization, a tool for multimedia data analysis, and a tool for movie editing. With these tools, linear information design is viewed as a concurrent process of framing parts and determining the order of the parts. In designing these tools, visual interaction design has been a center of our project. Our design priority has been put in minimizing the user's cognitive load in creating and modifying parts in a space, and manipulating them in the space. This paper first presents a brief philosophy underneath the system development, and describes interaction techniques used in the tools, such as how a user distinguishes objects positioned in the space, how a user resizes the space by dragging objects toward one of its edges, and how a user sees a trajectory of the objects the user is moving in the space.

This paper reports our case study on an ongoing interaction-design-centered software development project (ART project) viewed as an evolutionary collective creative process. In this project, a visual interaction designer and an expert programmer have collaboratively produced a series of interactive software tools, including a various types of movie players, innovative 3D visualizations and application systems. Visual interaction design is viewed as a process of seeking for compromises between what are desirable (expressed by the designer) and what are possible (expressed by the programmer). In the collaboration, each of the designer and the programmer collects, represents, interacts with, and reflects on a various types of visual representations. This paper characterizes the visual interaction design task, presents our framework to analyze the creative processes, and reports in detail how their creative processes have been carried out.

Jun is a large open-source graphics and multimedia library. It is object-oriented and supports 3D geometry, topography and multimedia. This paper reviews the development of the Jun library from five perspectives: open-source, software evolution processes, development styles, technological support, and development data. It concludes with lessons learned from the perspective of a for-profit company providing open-source object-oriented software to the community.

The goal of this research is to study the role and effects of the use of animated information visualization in the early stages of exploratory data analysis tasks. Despite the existence of a large body of research on information visualization, there is little known regarding how and when one should use and how to interact with animated visualization to help explore data. By animated visualization, we mean a type of information visualization technique that produces autonomous motions of representations. This research explored the issue from two aspects: what cognitive effects animated information visualization has, and what interactions people have with animated visualization when exploring data. We conducted two user studies to investigate each aspect, and identified research challenges for designing an interactive animated information visualization environment that supports the early stages of exploratory data analysis. These findings help us further study how to extend the notions developed in spatial visualization to temporal visualization - e.g. what focus+context means when applied to the time dimension in animated visualization.

This paper proposes different parameterized linear matrix inequality (PLMI) characterizations for fuzzy control systems. These PLMI characterizations are, in turn, relaxed into pure LMI programs, which provides tractable and effective techniques for the design of suboptimal fuzzy control systems. The advantages of the proposed methods over earlier ones are then discussed and illustrated through numerical examples and simulations.

The goal of our research is to develop computer systems that support designers' collective creativity; such systems support individual creative aspects in design through the use of representations created by others in the community. We have developed two systems, IAM-eMMa and EVIDII, that both aim at supporting designers in finding visual images that would be useful for their creative design task. IAMeMMa uses knowledge-based rules, which are constructed by other designers, to retrieve images related to a design task and infers the underlying "rationale" when a designer chooses one of the images. EVIDII allows designers to associate affective words and images, and then shows several visual representations of the relationships among designers, images and words. By observing designers interacting with the two systems, we have identified that systems for supporting collective creativity need to be based on design knowledge that (1) is contextualized, (2) is respectable and trustful, and (...