Oscillating superleak transducer of second sound: Amplitude and linewidth

Two oscillating superleak transducers, one serving as generator, the other as detector, of first and second sound, situated at opposite ends of a one-dimensional resonance cavity, are considered. Included in the analysis are the dissipative effects of normal viscous slip and thermal diffusion through the porous membrane. The calculated amplitude and linewidth of the receiver response, both close to and away from the membrane resonance, show good agreement with available experimental data.     

Der Stand der Forschung zur Erfolgsmessung von Informationssystemen

Measuring information systems (IS) success is of great interest to both researchers and practitioners. This article examines multidimensional approaches to measuring IS success and explores the current state of IS success research through a literature review and by classifying articles published between 2003 and 2007. Based on a total of 41 academic journal and conference publications, the relevant research carried out is identified, while the research results are categorized, consolidated, and discussed. The results show that the dominant empirical research analyzes the individual impact of a certain type of information system by ascertaining users’ evaluation of it by means of surveys and then applying structural equation modeling. The DeLone and McLean Information Systems Success Model is the main theoretical basis of the reviewed empirical studies. This article provides researchers with a comprehensive review and structuring of IS success research. Furthermore, opportunities for additional development are identified and future research directions suggested.     

Approximation of graph edit distance based on Hausdorff matching

Graph edit distance is a powerful and flexible method for error-tolerant graph matching. Yet it can only be calculated for small graphs in practice due to its exponential time complexity when considering unconstrained graphs. In this paper we propose a quadratic time approximation of graph edit distance based on Hausdorff matching. In a series of experiments we analyze the performance of the proposed Hausdorff edit distance in the context of graph classification and compare it with a cubic time algorithm based on the assignment problem. Investigated applications include nearest neighbor classification of graphs representing letter drawings, fingerprints, and molecular compounds as well as hidden Markov model classification of vector space embedded graphs representing handwriting. In many cases, a substantial speedup is achieved with only a minor loss in accuracy or, in one case, even with a gain in accuracy. Overall, the proposed Hausdorff edit distance shows a promising potential in terms of flexibility, efficiency, and accuracy.     

The influence of third-body particles on wear rate in unicondylar knee arthroplasty: a wear simulator study with bone and cement debris

The reduced intraoperative visibility of minimally invasive implanted unicondylar knee arthroplasty makes it difficult to remove bone and cement debris, which have been reported on the surface of damaged and retrieved bearings. Therefore, the aim of this study was to analyze the influence of bone and cement particles on the wear rate of unicompartmental knee prostheses in vitro. Fixed bearing unicompartmental knee prostheses were tested using a knee-wear-simulator according to the ISO standard 14243-1:2002(E) for 5.0 million cycles. Afterwards bone debris (particle size 671 ± 262 μm) were added to the test fluid in a concentration of 5 g/l for 1.5 million cycles, followed by 1.5 million cycles blended with cement debris (particle size 644 ± 186 μm) in the same concentration. Wear rate, knee-kinematics and wear-pattern were analyzed. The wear rate reached 12.5 ± 1.0 mm³/million cycles in the running-in and decreased during the steady state phase to 4.4 ± 0.91 mm³/million cycles. Bone particles resulted in a wear rate of 3.0 ± 1.27 mm³/million cycles with no influence on the wear rate compared to the steady state phase. Cement particles, however, lead to a significantly higher wear rate (25.0 ± 16.93 mm³/million cycles) compared to the steady state phase. The careful removal of extruded cement debris during implantation may help in reducing wear rate. Bone debris are suggested to have less critical influence on the prostheses wear rate.     

纤维基材料的仿生学研究动向

纤维基技术的应用对仿生学的成功发展呈现出巨大的潜力,因为宇宙成物在生长过程、多毛结构和增强纤维方面具有许多相似性.约七年前,邓肯道夫纺织技术与工艺研究所协同众位生物学家一起开创了仿生学的研发,至今方兴未艾.