Integrating context-free and context-dependent attentional mechanisms for gestural object reference

We present a vision system for human-machine interaction based on a small wearable camera mounted on glasses. The camera views the area in front of the user, especially the hands. To evaluate hand movements for pointing gestures and to recognise object references, an approach to integrating bottom-up generated feature maps and top-down propagated recognition results is introduced. Modules for context-free focus of attention work in parallel with the hand gesture recognition. In contrast to other approaches, the fusion of the two branches is on the sub-symbolic level. This method facilitates both the integration of different modalities and the generation of auditory feedback.Published online: 5 October 2004Robert Rae: Now at PerFact Innovation, Lampingstr. 8, 33615 Bielefeld, Germany     

COLLATE – A collaboratory supporting research on historic European films

In the COLLATE project, we aim to design and implement a Web-based collaboratory for archives, scientists, and end users working with digitized cultural material. Our example domain is the historic film documentation comprising digitized material about European films of the early 20th century. Designed as a content- and context-based knowledge working environment for distributed user groups, the COLLATE system supports both individual work and collaboration of domain experts who are analyzing, evaluating, indexing, and annotating material in the data repository. The system provides appropriate task-based interfaces for indexing and annotating. As a multifunctional means of in-depth analysis, annotations can be made individually but also collaboratively, for example in the form of annotation of annotations. Combining results from manual and automatic indexing procedures, elaborate content- and context-based information retrieval mechanisms can be applied.     

Element distinctness on one-tape Turing machines: a complete solution

We give a complete characterization of the complexity of the element distinctness problem for n elements of bits each on deterministic and nondeterministic one-tape Turing machines. We present an algorithm running in time for deterministic machines and nondeterministic solutions that are of time complexity . For elements of logarithmic size , on nondeterministic machines, these results close the gap between the known lower bound and the previous upper bound . Additional lower bounds are given to show that the upper bounds are optimal for all other possible relations between m and n. The upper bounds employ hashing techniques, while the lower bounds make use of the communication complexity of set disjointness.Received: 23 April 2001, Published online: 2 September 2003Holger Petersen: Supported by Deutsche Akademie der Naturforscher Leopoldina, grant number BMBF-LPD 9901/8-1 of Bundesministerium für Bildung und Forschung.     

Development of error-compensating UI for autonomous production cells

This contribution deals with the impact of human error on the overall system reliability in flexible manufacturing systems (FMS). Autonomous production cells are used to illustrate an error-compensating system design on the basis of Sheridan's (1997) paradigm of supervisory control. In order to specify human errors and their effects in terms of system disturbances, a taxonomy of system disturbances is recommended. This taxonomic approach was derived by a value benefit analysis and is based on HEDOMS (Human Error and Disturbance Occurrence in Manufacturing Systems) with slight modifications and Reason's GEMS (Generic Error Modelling System). The taxonomy is used for data acquisition. Next, a risk priority equivalent to FMEA (Failure Mode and Effect Analysis) is introduced to structure the data according to their relevance. Then, Vicente's and Rasmussen's guidelines (1987) for an ecological interface design are related to the paradigm of supervisory control. On the basis of these guidelines four case studies are presented to show their successful applicability for interface design in FMS.     

Highly efficient transmission gratings in fused silica for chirped-pulse amplification systems

We report on highly efficient transmission gratings in fused silica with a grating period of 800 nm generated by electron-beam lithography. At a wavelength of 1060 nm, 95% diffraction efficiency is achieved under Littrow conditions. The damage threshold, extremely enhanced compared with conventional gold-coated diffraction gratings, makes these gratings the key elements in high average power (>100 W) femtosecond fiber chirped-pulse amplification systems.     

String matching with simple devices

With the help of a general simulation technique of deterministic finite two-way multi-head automata by automata with blind heads we show O(n²/logn) to be an upper time bound on string matching. This result is tight by a previously known lower bound.     

Interactive lectures: Effective teaching and learning in lectures using wireless networks

Among the severe instructional shortcomings of lectures is their lack of interactivity. To overcome these problems, the learning environment of the interactive lecture is introduced, in which students and lecturer interact by using mobile computers in a wireless network. In an experimental study, 44 students participated in interactive and in conventional lecture meetings. A quiz service that allowed question to be posted, students’ answers to be evaluated, and the results to be presented graphically, was implemented on mobile computers. The participants rated the interactive condition better, also reporting higher levels of attention, activity and perceived learning success for this condition. Objective measures indicated a slight but insignificant difference toward better learning results in the interactive condition.     

Measurement of CH4-concentration in HMDSO-containing process plasmas by quantum cascade laser absorption spectroscopy

For thin film deposition or plasma etching often organic precursors are used in the process plasma and related transient species are formed. In general it is not possible to measure the converted quantity of these precursors directly. In the present work we have used a special laser absorption spectroscopy to investigate characteristic molecular lines in the plasma to determine the concentration of stable organic molecules. Quantum cascade laser absorption spectroscopy (QCLAS) is a rather new technique for the precise measurement of absolute molecule concentrations. QCL’s can be operated at room temperature. They emit light within the mid infrared and have similar spectroscopic characteristics to Tunable Diode Lasers (TDL). The commercially available system Q-MACS (Quantum Cascade Laser Measurement and Control System) offers a solid platform for the measurement of absolute molecule concentrations in plasmas and gas mixtures. The used Q-MACS is due to its laser characteristics particularly well suitable for determination of the concentrations of acetylene and methane. Molecular concentrations of methane were measured in hexamethyldisiloxane (HMDSO) containing plasmas, too. The methane concentration was found to depend on rf power and HMDSO flow.