Ontology-based mobile augmented reality in cultural heritage sites: information modeling and user study

Augmented reality (AR) has received much attention in the cultural heritage domain as an interactive medium for requesting and accessing information regarding heritage sites. In this study, we developed a mobile AR system based on Semantic Web technology to provide contextual information about cultural heritage sites. Most location-based AR systems are designed to present simple information about a point of interest (POI), but the proposed system offers information related to various aspects of cultural heritage, both tangible and intangible, linked to the POI. This is achieved via an information modeling framework where a cultural heritage ontology is used to aggregate heterogeneous data and semantically connect them with each other. We extracted cultural heritage data from five web databases and modeled contextual information for a target heritage site (Injeongjeon Hall and its vicinity in Changdeokgung Palace in South Korea) using the selected ontology. We then implemented a mobile AR application and conducted a user study to assess the learning and engagement impacts of the proposed system. We found that the application provides an agreeable user experience in terms of its affective, cognitive, and operative features. The results of our analysis showed that specific usage patterns were significant with regard to learning outcomes. Finally, we explored how the study’s key findings can provide practical design guidance for system designers to enhance mobile AR information systems for heritage sites, and to show system designers how to support particular usage patterns in order to accommodate specific user experiences better.

     

Architectural Methodology Based on Intentional Configuration of Behaviors

Intelligence has been an object of study for a long time. Different architectures try to capture and reproduce these aspects into artificial systems (or agents), but there is still no agreement on how to integrate them into a general framework. With this objective in mind, we propose an architectural methodology based on the idea of intentional configuration of behaviors. Behavior‐producing modules are used as basic control components that are selected and modified dynamically according to the intentions of the agent. These intentions are influenced by the situation perceived, knowledge about the world, and internal variables that monitor the state of the agent. The architectural methodology preserves the emergence of functionality associated with the behavior‐based paradigm in the more abstract levels involved in configuring the behaviors. Validation of this architecture is done using a simulated world for mobile robots, in which the agent must deal with various goals such as managing its energy and its well‐being, finding targets, and acquiring knowledge about its environment. Fuzzy logic, a topologic map learning algorithm, and activation variables with a propagation mechanism are used to implement the architecture for this agent.     

Evaluation of a Computer-Assisted, 2-D Virtual Reality System for Training People With Intellectual Disabilities on How to Shop.

Objective: To evaluate the effectiveness of a 2-D virtual reality (VR) program for training people with intellectual disabilities to shop. Study Design: Pretest and posttest quasi-experimental design. Participants: Sixteen persons with intellectual disabilities (age 17-23 years; IQ = 40-54). Intervention: A VR program or a conventional program training them in supermarket-shopping skills. Main Outcome Measure: Checklist for supermarket-shopping skills. Results: Participants in both training groups showed significant improvement. There was no significant difference in effectiveness between the two methods. Conclusions: The VR program appears effective in training people with intellectual disabilities in an important community living skill. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Direct vapor phase growth process and robust photoluminescence properties of large area MoS2 layers

There has been growing research interest in the use of molybdenum disulfide in the fields of optoelectronics and energy harvesting devices, by virtue of its indirect-to-direct band gap tunability. However, obtaining large area thin films of MoS2 for future device applications still remains a challenge. In the present study, the amounts of the precursors （S and MOO3） were varied systematically in order to optimize the growth of highly crystalline and large area MoS2 layers by the chemical vapor deposition method. Careful control of the amounts of precursors was found to the key factor in the synthesis of large area highly crystalline flakes. The thickness of the layers was confirmed by Raman spectroscopy and atomic force microscopy. The optical properties and chemical composition were studied by photoluminescence （PL） and X-ray photoelectron spectroscopy. The emergence of strong direct excitonic emissions at 1.82 eV （A-exciton, with a normalized PL intensity of -55 × 10^3） and 1.98 eV （B-exciton, with a normalized PL intensity of -5 × 10^3） of the sample at room temperature clearly indicates the high luminescence quantum efficiency. The mobility of the films was found to be 0.09 cm^2/（V.s） at room temperature. This study provides a method for the controlled synthesis of high-quality two-dimensional （2D） transition metal dichalcogenide materials, useful for applications in nanodevices, optoelectronics and solar energv conversion.     

An investigation of the effects of the tool path on the removal of material in polishing

Uniformity of removal affects the finishing, and in some cases, the form accuracy of the polished surface. Tool paths are required for the automation of surface polishing. How the tool path may affect the removal of material in polishing is investigated in this paper. An analysis of how removal at a location due to polishing along adjacent path lines is presented. Four tool paths reportedly used in polishing are covered: scanning, bi-scanning, Hilbert and Peano paths. Removal in the inner surface as well as near the edges of surfaces is examined through simulations and analysis. The results show that, for the same path pitch, the peak-to-valley height (h_pv) in the inner part of the removal map is the same for scanning, bi-scanning and Peano, while the texture of the removal maps can be quite different. The h_pv values of Hilbert are more than double those of Peano, although both are fractal paths. Removal near the edges is particularly severe for scanning-type tool paths. The ratio of the edge peak height to the inner peak height is about 1.6 on average for scanning. The uniformity of removal further deteriorates as the ellipticity of the tool contact increases. When the contact direction is closely aligned with the path line direction, that ratio goes up to about 2.9 for contact ellipticity of 2. Polishing experiments have also been conducted. Both experiments and simulations point to the presence of edge effects in scanning paths and its absence in Peano paths. It is further proposed that, for more uniform removal of material: (1) changes in the tool path direction should be well distributed and (2) the direction of the path lines should be well balanced over the entire surface.     

Influence of Photolithography on the Cross-Sectional Shape of Polysiloxane as an Optical Waveguide Material on Printed Circuit Boards

Optical waveguide cross-sectional shapes that deviate from rectangles or squares may cause significant loss of signal. In this study, a photolithography approach was adopted to fabricate waveguides on printed circuit boards, using photo-imageable polysiloxane as a waveguide material. The effects of I-line ultraviolet (UV) lamp exposure, 355-nm Nd:YAG laser direct imaging, and 248-nm excimer laser direct imaging on the cross-sectional shape of waveguides were investigated. For I-line UV lamp exposure, increasing the exposure time could cause changes in the tilt angle of the waveguides from negative (inverted trapezoid) to positive (trapezoid). To obtain rectangular waveguides, the optimum I-line UV lamp exposure time was found to be around 150 s. From the results for 355-nm Nd:YAG laser direct imaging, the width and tilt angle of the waveguides varied with the energy density of the laser beam irradiating the core materials, being controlled by the repetition rate and focus. Lowering the laser energy density could produce waveguides with small widths and tilt angles. Excimer laser direct imaging at 248 nm was found to be unsuitable for waveguide patterning since the core materials could not be cured at this wavelength.     

Variable-bit-rate speech transmission using punctured convolutionalcodes

Rate (n-1)/n punctured convolutional codes are very effective in conjunction with embedded differential pulse code modulation (EDPCM) in variable-bit-rate speech transmission. The authors investigate the performance of this variable-bit-rate EDPCM system in terms of probability of bit error and audio signal-to-noise ratio (SNR) versus channel SNR in an additive white Gaussian noise and Rayleigh fading channel using soft-decision decoding for specific sets of code generators of punctured convolutional codes. The results show that different sets of code generators affect the performance in terms of both the probability of bit error and the audio SNR. Improvements were obtained in the cases of Gaussian nonfading and Rayleigh fading channels using soft-decision decoding     

Tunable dual-wavelength-switching fiber grating laser

We report a tunable dual-wavelength-switching fiber grating laser by exploiting the large homogeneous gain broadening in erbium (Er)-doped fiber to suppress simultaneous lasing. Wavelength switching was accomplished through a novel design which has two overlapping cavities sharing a single-gain medium. The loss corresponding to one of the lasing wavelengths can be modulated via an optical chopper. Output power of about 6 mW and extinction ratio up to 50 dB were observed. The lasing wavelengths were tunable and switching was demonstrated for wavelength separations ranging from 0.35 to 23.5 nm     

Pump-induced thermal effects in Er-Yb fiber grating DBR lasers

Large absorption of 980-nm pumping in Er-Yb doped fibers causes significant temperature differentials along small length of the fibers. When pumped with 40 mW of power, unequal Bragg wavelength shifts of 0.25 and 0.16 mm were measured in the respective 6- and 10-mm-long Bragg reflectors constructed around the Er-Yb core of a 2.5-cm-long DBR laser. This causes large fluctuation in the laser's output power. Stable operation resumed with increased pump power. At 68 mW of pump power, 0.32-nm shift in lasing wavelength (corresponding to a temperature rise of 38°C) was measured in the distributed Bragg reflector fiber laser