Boundary-trimmed 3D triangular mesh segmentation based on iterative merging strategy

This paper presents a segmentation algorithm for 3D triangular mesh data. The proposed algorithm uses iterative merging of adjacent triangle pairs based on their orientations. The oversegmented regions are merged again in an iterative region merging process. Finally, the noisy boundaries of each region are refined. The boundaries of each region contain perceptually important geometric information of the entire mesh model. According to the purpose of the segmentation, the proposed mesh-segmentation algorithm supports various types of segmentation by controlling parameters.     

Supervisory control of timed discrete event systems under partial observation based on activity models and eligible time bounds

To avoid the state–space explosion by including tick events in timed discrete event systems (DESs) under partial observation, a notion of eligible time bounds is introduced and based on the notion, controllability and observability conditions of languages are presented. In particular, this paper shows that these controllability and observability conditions are necessary and sufficient for the existence of a supervisor to achieve the given language specification.     

Augmenting elementary school education with VR

At the University of Illinois at Chicago's Electronic Visualization Laboratory, we use virtual reality technology to complement real-world experiences rather than replace them. For more than two years, we've been deploying ImmersaDesk applications in a Chicago-area elementary school. We want to know whether these virtual environments (VEs) help children make sense of mathematics and scientific phenomena. If so, can educators adapt them to the realities of elementary school learning and teaching? Our experience indicates that VR can successfully augment scientific education as well as help to equalize the learning environment by engaging students of all levels     

Spatial-temporal antialiasing

A framework for discussing the motion blur image generation process is formulated. Previous work is studied in the context of this framework. Due to the implicit assumptions on low temporal frequencies in most motion blur algorithms, issues involved in large screen space movements and fast illumination changes in time have not been adequately addressed so far. A new approach that does not make these assumptions is introduced to solve the spatial-temporal geometric and shading aliasing problems separately. Based on newly developed adaptive algorithms in the spatial-temporal domain, an implementation of the new approach is developed to efficiently deliver high-quality motion blurred images in general computer graphics production environments     

Characterization of electroplated nickel

 Properties of electroplated nickel such as crystallographic texture, Young's modulus, strength and microstructure strongly depend on the parameter mean current density used for electrodeposition. By means of micro tensile testing mechanical material parameters were determined. At low mean current density (2 mA/cm²) brittle layers with high Young's modulus and high strength were obtained, whereas at high current density (15 mA/cm²) ductile layers with low Young's modulus and low strength were deposited. Received: 10 August 2001/Accepted: 24 September 2001 Parts of the work were carried out within the project ELMINOS, which is supported by the state of North Rhine-Westphalia, Germany. The equipment used for the experiments was funded by the state of North Rhine-Westphalia. We would like to express our sincere gratitude to Mirko Hofmann for his assistance in performing the measurements of indentation hardness. The participation of Cho and Hemker was sponsored by the Defense Advanced Research Projects Agency (DARPA) and Air Force Research Laboratory, Air Force Material Command, USAF, under agreement number F30602-99-2-0553. This paper was presented at the Fourth International Workshop on High Aspect Ratio Microstructure Technology HARMST 2001 in June 2001.     

Estimation of ultrasonic guided wave mode conversion in a plate with thickness variation

The hybrid boundary element method aimed at analyzing Lamb wave scattering from defects can provide us with an excellent numerical tool for tackling complicated mode conversion phenomena under waveguide thickness variation. In this paper, utilization of hybrid boundary element modeling for specific Lamb wave mode incidence situations with special energy distributions along the structural cross section is proposed for estimating reflection and transmission from various scatterers, such as a step discontinuity and tapered parts of a waveguide, etc. Interaction of individual Lamb wave modes with scatterers that represent arbitrary thickness variation along the direction of guided wave propagation is investigated by calculating the scattered fields for varying incident modes, frequency, and scatterer shape. The mode conversion phenomena through step discontinuity in a plate are also experimentally explored. The theoretical predictions of reflection and transmission by boundary element methods and the utility of dispersion curves are compared with experiments for specific modes. Results in this paper can be used to improve inspection sensitivity and penetration power for a variety of practical NDE applications, notably those in which thickness variation is found. In addition, the feasibility of inspecting sections located behind a waveguide thickness variation region and subsequent mode control will also be discussed.     

Cloning and functional characterization of a Caenorhabditis elegans muscarinic acetylcholine receptor

A cDNA clone encoding a muscarinic acetylcholine receptor (mAChR) has been isolated from the nematode Caenorhabditis elegans. The nematode mAChR, consisted of 585 amino acids, displays a high degree of amino acid sequence homology to other invertebrate and vertebrate mAChRs. Excluding a highly variable middle portion of the third intracellular loop, the C. elegans mAChR shares about 51% amino acid sequence identity with a Drosophila mAChR and 42-44% identity with human m1-m5 mAChR subtypes. Comparison of the cDNA sequence with the corresponding genomic sequence reveals that the C. elegans mAChR gene contains ten introns, eight of them in the coding region. Pharmacological profiles of the C. elegans mAChR expressed in Chinese hamster ovary (CHO) cells were shown to be similar to those of mammalian counterparts, indicating that ligand binding domains of the receptor have been conserved during evolution. When this cloned receptor was expressed in Xenopus oocytes, acetylcholine evoked a transient Cl- current. Furthermore, activation of the receptor with oxotremorine, acetylcholine or carbachol resulted in the stimulation of phosphatidylinositol metabolism in CHO cells, suggesting that the receptor is coupled to phospholipase C activation.     

Synthesis of Al2O3-WC composite powder by SHS process

Al₂O₃-WC composite powder was synthesized by self-propagating high-temperature synthesis using Al powder as a reducing agent. WC, W₂C and Al₂O₃ were concurrently formed in WO₃-Al-C system. It was found that the complete reaction was achieved with excessive addition of carbon and appropriate processing parameters such as degree of dilution, particle size of aluminum, pellet compaction pressure and carbon source. The final product which was leached by 50% 1 : 4 HNO₃ + HF diluted solution was consisted of Al₂O₃-55wt%WC having 2–3 m of mean particle size.     

Low-voltage characteristics of MgO-CaO films as a protective layer for AC plasma display panels by e-beam evaporation

The MgO-CaO composites films were prepared by e-beam evaporation to improve both operating voltages and memory coefficient of a protective layers for AC plasma display panels (PDPs). The effects of CaO addition to the conventional MgO films on both the electrical properties and the structural changes of the Mg_1–xCa_xO thin films deposited on the slide glass substrates were investigated. Atomic force microscopy (AFM) results revealed that the Mg_0.8Ca_0.2O film had a very rough surface due to the formation of a second phase on the surface. By adding controlled amount of CaO, the Mg-Ca-O films showed a firing voltage of 176 V that is lower than that of the conventional 100% MgO film. The deposition rates of 40–100 nm/min were obtained as a function of [CaO/(MgO+CaO)] ratio of the evaporation source materials.