An interval finite element approach for the calculation of envelope frequency response functions

This paper focusses on the application of the interval finite element method in dynamic analyses. It describes a methodology for calculating frequency response function envelopes from a finite element model containing imprecise parameters defined as interval uncertainties. The resulting envelope functions give a conservative approximation of the possible range of the frequency response function, taking into account that the uncertain parameters in the model can adopt any value in their presumed uncertainty intervals. The methodology is based on the modal superposition principle. It consists of an interval aritmethic algorithm which processes the results of a preliminary global optimization performed on the modal parameters. The algorithm is constructed such that it optimally combines the advantages of both the anti‐optimization and the interval arithmetic strategy for general numerical interval calculations. In the first stage of the development, the modal parameter ranges of each individual mode are independently combined in the modal response contributions. This yields the modal rectangle (MR) method. In order to remedy the high conservatism inherent to the MR method, the exact eigenfrequency ranges are added to the analysis. This results in the modal rectangle method with eigenfrequency interval correction (MRE). A second improvement consists of adding extra delimiters to the MRE modal parameter range approximation. This is achieved by performing an extra optimization on the modal response contributions at discrete frequencies. The method is referred to as the locally optimized modal rectangle method with eigenfrequency interval correction (OMRE). Finally, a numerical example illustrates the different algorithms. Copyright © 2004 John Wiley & Sons, Ltd.     

PCA document reconstruction for email classification

This paper presents a document classifier based on text content features and its application to email classification. We test the validity of a classifier which uses Principal Component Analysis Document Reconstruction (PCADR), where the idea is that principal component analysis (PCA) can compress optimally only the kind of documents-in our experiments email classes-that are used to compute the principal components (PCs), and that for other kinds of documents the compression will not perform well using only a few components. Thus, the classifier computes separately the PCA for each document class, and when a new instance arrives to be classified, this new example is projected in each set of computed PCs corresponding to each class, and then is reconstructed using the same PCs. The reconstruction error is computed and the classifier assigns the instance to the class with the smallest error or divergence from the class representation. We test this approach in email filtering by distinguishing between two message classes (e.g. spam from ham, or phishing from ham). The experiments show that PCADR is able to obtain very good results with the different validation datasets employed, reaching a better performance than the popular Support Vector Machine classifier.     

C-BiLDA extracting cross-lingual topics from non-parallel texts by distinguishing shared from unshared content

We study the problem of extracting cross-lingual topics from non-parallel multilingual text datasets with partially overlapping thematic content (e.g., aligned Wikipedia articles in two different languages). To this end, we develop a new bilingual probabilistic topic model called comparable bilingual latent Dirichlet allocation (C-BiLDA), which is able to deal with such comparable data, and, unlike the standard bilingual LDA model (BiLDA), does not assume the availability of document pairs with identical topic distributions. We present a full overview of C-BiLDA, and show its utility in the task of cross-lingual knowledge transfer for multi-class document classification on two benchmarking datasets for three language pairs. The proposed model outperforms the baseline LDA model, as well as the standard BiLDA model and two standard low-rank approximation methods (CL-LSI and CL-KCCA) used in previous work on this task.     

Monitoring poly(3-hydroxybutyrate) production in cupriavidus necator DSM 428 (H16) with raman spectroscopy

This study explored the potential of Raman spectroscopy for the analysis of poly(3-hydroxybutyrate) (PHB) in bacteria. PHB can be formed in large amounts by certain bacteria as a storage material and is of high importance for industrial biodegradable plastic production. Raman spectra were collected from Cupriavidus necator DSM 428 (H16), from its non-PHB-producing mutant strain C. necator DSM 541, and from pure PHB, in order to determine at which Raman shifts a contribution of PHB in bacterial spectra can be expected. The Raman band intensity at ca. 1734 cm(-1) appeared to be suitable for the monitoring of PHB production and consumption. These intensities were linearly related to the PHB concentration (mg L(-1) culture) determined by parallel HPLC analysis. Therefore, Raman spectroscopy is considered as a fast and noninvasive technique for the determination and monitoring of the PHB content in bacteria.     

Solvent‐ and Metal‐Free Ketonization of Fatty Acid Methyl Esters and Triacylglycerols with Nitrous Oxide

Herein we report a new, one‐step procedure for the metal‐free ketonization of unsaturated fatty acid methyl esters and triacylglycerol mixtures with nitrous oxide (N₂O). The conversion of various substrates can be tuned by parameters such as temperature, reaction time and N₂O partial pressure. This ketonization chemistry offers various advantages over the classic Wacker catalytic process and a state‐of‐the‐art two‐step procedure via intermediate epoxides.     

Treatment of nonunion of the humerus using the Ilizarov external fixator

Ilizarov's method of monofocal compression was used in 30 humeri with a diaphyseal pseudarthrosis. Twenty-one patients had previous surgery but had loosening of the osteosynthesis material. Nine patients initially were treated with a hanging cast, resulting in interfragmentary distraction. Fourteen nonunions were hypertrophic, and 16 were atrophic, of which six were infected. A complete circular frame was used only in the first nine patients, whereas the remaining 21 patients were treated with the modified semicircular fixator. Union was obtained in all but two patients, with an average consolidation time of 4.5 months (range, 2.5-10 months). No patient required additional bone grafting. Apart from superficial pin tract infection seen in most of the patients, three had a minor temporary sensory neurologic problem. Four patients experienced a second fracture after removal of the fixator that required a second application of an Ilizarov frame. Although similar results with regard to union are reported after plate osteosynthesis, there was no radial nerve palsy or deep infection in this series, indicating that the treatment by the Ilizarov technique is associated with less complications. The authors' findings suggest that the Ilizarov method is a reliable treatment for humeral nonunions, even after multiple previous operations or in the event of infection.     

Interacting with the Music Paint Machine: Relating the constructs of flow experience and presence

In this paper we report on the results of an experiment on the experience of flow and presence while engaging with an interactive music system, the Music Paint Machine. This music system provides a game-like environment in which a musician can create a digital painting by playing an acoustic musical instrument, by moving the body in different directions, and by selecting colours using a pressure mat. The experiment aimed at getting a better insight into the possible relationship between flow experience and presence. Based on the definition of flow as a combination of the highest level of presence (presence-as-feeling) and a positive emotional state (Riva et al., 2004a), we hypothesized that presence has a predictive value for flow. Sixty-five musicians, both amateur and professional, participated in the experiment. Flow experience was measured with the Flow State Scale (Jackson and Eklund, 2004). Presence was measured with an in-house designed presence questionnaire. Results showed a significantly strong correlation between flow and presence. Moreover, the scores for presence significantly predicted the Flow State Scale, and explained a significant proportion of variance in the Flow State Scale. Furthermore, many significant associations were found between flow and presence variables, among which the most significant were the strong correlation (Spearman’s rank) between the naturalness of using the system and the Flow State Scale and between the feeling of non-mediation and the Flow State Scale.     

TLP Characterization of large gate width devices

The maximum transient voltage of a MOSFET device is one of the key parameters for power applications. Therefore, transmission line pulse (TLP) characterization is used to assess this. TLP measurements on large gate width devices are difficult to perform due to gate oscillations.In this paper, a method to avoid oscillation when measuring large gate width devices is presented. Device simulations are presented showing gate side oscillation triggered by the rising edge of the 100 ns TLP pulse. Adding a resistor in series with the gate largely damps the oscillation. Comparison between system level simulation and captured TLP waveforms is done and the correlation is discussed.