NETMAN: The design of a collaborative wearable computer system

This paper presents a wearable groupware system designed to enhance the communication and cooperation of highly mobile network technicians. It provides technicians in the field with the capabilities for realtime audioconferencing, transmission of video images back to the office, and contextsensitive access to a shared notebook. An infrared locationtracking device allows for the automatic retrieval of notebook entries depending on the user's current location.     

Two-Dimensional Palladium Diselenide with Strong In-Plane Optical Anisotropy and High Mobility Grown by Chemical Vapor Deposition

Two-dimensional (2D) palladium diselenide (PdSe₂) has strong interlayer coupling and a puckered pentagonal structure, leading to remarkable layer-dependent electronic structures and highly anisotropic in-plane optical and electronic properties. However, the lack of high-quality, 2D PdSe₂ crystals grown by bottom-up approaches limits the study of their exotic properties and practical applications. In this work, chemical vapor deposition growth of highly crystalline few-layer (≥2 layers) PdSe₂ crystals on various substrates is reported. The high quality of the PdSe₂ crystals is confirmed by low-frequency Raman spectroscopy, scanning transmission electron microscopy, and electrical characterization. In addition, strong in-plane optical anisotropy is demonstrated via polarized Raman spectroscopy and second-harmonic generation maps of the PdSe₂ flakes. A theoretical model based on kinetic Wulff construction theory and density functional theory calculations is developed and described the observed evolution of “square-like” shaped PdSe₂ crystals into rhombus due to the higher nucleation barriers for stable attachment on the (1,1) and (1,−1) edges, which results in their slower growth rates. Few-layer PdSe₂ field-effect transistors reveal tunable ambipolar charge carrier conduction with an electron mobility up to ≈294 cm² V⁻¹ s⁻¹, which is comparable to that of exfoliated PdSe₂, indicating the promise of this anisotropic 2D material for electronics.     

View Planning for Multi-View Stereo 3D Reconstruction Using an Autonomous Multicopter

Multi-view stereo algorithms are an attractive technique for the digital reconstruction of outdoor sites. Concerning the data acquisition process a vertical take off and landing UAV carrying a digital camera is a suitable platform in terms of mobility and flexibility in viewpoint placement. We introduce an automated UAV based data acquisition and outdoor site reconstruction system. A special focus is set on the problem of model based view planning using a coarse digital surface model (DSM) with minimal data preprocessing. The developed view planning heuristic considers a coverage, a maximum view angle and an overlapping constraint imposed by multi-view stereo reconstruction techniques. The time complexity of the algorithm is linear with respect to the size of the area of interest. We demonstrate the efficiency of the entire system in two scenarios, a building and a hillside.     

Experiences with the Implementation of Computerized Tools in Health Care Units: A Review Article

Demands for improved patient care as well as improved efficiency in the delivery of health care have increased dramatically in recent years. New technologies, including computers, are expected to play an important role in meeting these demands. The aim of this review is to identify the main challenges to the introduction of computer technology in health care and to identify what kinds of factors may promote or hamper the implementation process. A systematic search of relevant databases resulted in 299 hits related to implementation of computer technology in health care, of which 17 met all criteria for inclusion in this review. The following barriers to the adoption of computer technology were identified: negative attitudes, lack of knowledge, role adjustment related to the disruption of traditional work habits, and changes in established work roles. The dual needs to both assess and change attitudes were identified as crucial factors in allowing for the successful implementation of these new technologies. The challenges for future clinical work and research will be to influence the behavior and intentions of health care personnel, to focus on the benefits of introducing computer technology (CT) in health care units, and to make certain that the institution's leadership is fully supportive of the change. Furthermore, this review showed that if the introduction of computerized tools is going to succeed, an adequate training program is imperative.     

Classification of sediments on exposed tidal flats in the German Bight using multi-frequency radar data

We present a new method for the extraction of roughness parameters of sand ripples on exposed tidal flats from multi-frequency synthetic aperture radar (SAR) data. The method is based on the Integral Equation Model (IEM) which predicts the normalized radar cross-section (NRCS) of randomly rough dielectric surfaces. The data used for this analysis were acquired in the German Bight of the North Sea by the Spaceborne Imaging Radar-C/X-Band SAR (SIR-C/X-SAR) in 1994. In-situ measurements of the root-mean-squared (rms) height and the correlation length of the sand ripples clearly demonstrate a relationship between these roughness parameters and the C-band NRCS determined from an ERS SAR image. Using the IEM we have calculated NRCS isolines for the three frequency bands deployed by SIR-C/X-SAR (L, C, and X band), as a function of the rms height and the correlation length of the sand ripples. For each SIR-C/X-SAR image pixel these two roughness parameters were determined from the intersections of the NRCS isolines at different radar bands, and they were used for a crude sediment classification for a small test area at the German North Sea coast. Comparing our results with available sediment maps, we conclude that the presented method is very promising for tidal flat classification by using data from presently existing airborne and future spaceborne multi-frequency SAR systems.     

High-quality rendering of quartic spline surfaces on the GPU

We present a novel GPU-based algorithm for high-quality rendering of bivariate spline surfaces. An essential difference to the known methods for rendering graph surfaces is that we use quartic smooth splines on triangulations rather than triangular meshes. Our rendering approach is direct in the sense that since we do not use an intermediate tessellation but rather compute ray-surface intersections (by solving quartic equations numerically) as well as surface normals (by using Bernstein-Bézier techniques) for Phong illumination on the GPU. Inaccurate shading and artifacts appearing for triangular tesselated surfaces are completely avoided. Level of detail is automatic since all computations are done on a per fragment basis. We compare three different (quasi-) interpolating schemes for uniformly sampled gridded data, which differ in the smoothness and the approximation properties of the splines. The results show that our hardware based renderer leads to visualizations (including texturing, multiple light sources, environment mapping, etc.) of highest quality.     

Frequency domain sample maximum likelihood estimation for spatially dependent parameter estimation in PDEs

The identification of the spatially dependent parameters in Partial Differential Equations (PDEs) is important in both physics and control problems. A methodology is presented to identify spatially dependent parameters from spatio-temporal measurements. Local non-rational transfer functions are derived based on three local measurements allowing for a local estimate of the parameters. A sample Maximum Likelihood Estimator (SMLE) in the frequency domain is used, because it takes noise properties into account and allows for high accuracy consistent parameter estimation. Confidence bounds on the parameters are estimated based on the noise properties of the measurements. This method is successfully applied to the simulations of a finite difference model of a parabolic PDE with piecewise constant parameters.     

Phase Composition, Oxygen Content, and Thermal Conductivity of AIN(Y2O3) Ceramics

An indirect method to determine the oxygen dissolved in AIN is devised for AIN(Y₂O₃) ceramics and then related to thermal conductivity. Dissolved oxygen is determined by first constructing the AIN-rich corner of the AIN—Y₂O₃—Al₂O₃ phase diagram (isothermal section). This is achieved by (1) measuring the total oxygen content and subtracting from it the oxygen in the Y₂O₃, resulting in a virtual alumina content; (2) placing the sample composition on the diagram; (3) determining the phases present by XRD for each sample; and (4) drawing phase boundaries which best agree with the phases present. The intersection of these tie lines through the sample location with the AIN—Al₂O₃ axis then gives the particular Al₂O₃ oxygen content dissolved in the AIN lattice. For the system AIN—Y₂O₃—Al₂O₃, it is shown that it is indeed this fraction of the total oxygen content that has a decisive limiting influence on thermal conductivity of dense, polyphase AIN ceramics.