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Practical Experiments (practical + experiment)
Selected AbstractsPrior knowledge processing for initial state of Kalman filterINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 3 2010E. Suzdaleva Abstract The paper deals with a specification of the prior distribution of the initial state for Kalman filter. The subjective prior knowledge, used in state estimation, can be highly uncertain. In practice, incorporation of prior knowledge contributes to a good start of the filter. The present paper proposes a methodology for selection of the initial state distribution, which enables eliciting of prior knowledge from the available expert information. The proposed methodology is based on the use of the conjugate prior distribution for models belonging to the exponential family. The normal state-space model is used for demonstrating the methodology. The paper covers processing of the prior knowledge for state estimation, available in the form of simulated data. Practical experiments demonstrate the processing of prior knowledge from the urban traffic control area, which is the main application of the research. Copyright © 2009 John Wiley & Sons, Ltd. [source] Comparison of multivariate methods for robust parameter design in sheet metal spinningAPPLIED STOCHASTIC MODELS IN BUSINESS AND INDUSTRY, Issue 3 2004Corinna Auer Abstract Sheet metal spinning is a very complex forming process with a large number of quality characteristics. Within the scope of a joint project of the Department of Statistics and the Chair of Forming Technology the impact of process parameters (design factors) on important quality characteristics has been investigated both theoretically and experimentally. In the past, every response has been treated individually and uncontrollable disturbances (noise factors) have been neglected. Now this approach has been extended to robust multiresponse parameter design. For this, a review of common multivariate approaches for robust parameter design has been carried out, which also leads to the proposal of some new variants. In addition to the theoretical comparison, the methods were applied to data gained in the sheet metal spinning process. The obtained results were evaluated in terms of applicability, limitations and quality accuracy. Practical experiments confirmed the high degree of efficiency that the finally proposed method based on desirabilities promises. Copyright © 2004 John Wiley & Sons, Ltd. [source] Determination of the Rh factor: A practical illustrating the use of the polymerase chain reactionBIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION, Issue 1 2005Santiago Imperial Abstract A practical experiment on the PCR is described that has been used over several years as part of an undergraduate biochemistry and molecular biology course for chemistry students. In the first experimental session, students prepare their own DNA samples from epithelial cells of the mouth and use them as templates in the PCR. In the second session, they analyze the amplified DNA by electrophoresis and determine their Rh factor. [source] The 15N-CPMAS spectra of simazine and its metabolites: measurements and quantum chemical calculationsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2007A. E. Berns Summary DFT calculations are a powerful tool to support NMR studies of xenobiotics such as decomposition studies in soil. They can help interpret spectra of bound residues, for example, by predicting shifts for possible model bonds. The described bound-residue models supported the hypothesis of a free amino side chain already suspected by comparison with the experimental data of the standards. No match was found between the calculated shifts of amide bondings of the amino side chains (free or substituted) and the experimental NMR shifts of a previous study. In the present paper, first-principles quantum chemical calculations were used to support and check the interpretation of the 15N cross polarization-magic angle spinning nuclear magnetic resonance (15N-CPMAS NMR) spectra of simazine and its metabolites. Density functional theory (DFT) calculations were performed using Gaussian 03 and the nuclear magnetic shielding tensors were calculated using the Gauge-Independent Atomic Orbital (GIAO) method and B3LYP/6,311+G(2d,p) model chemistry. Good agreement was reached between the calculated and measured chemical shifts of the core nitrogens and the lactam and lactim forms of the hydroxylated metabolites could be clearly distinguished. The calculated spectra showed that these metabolites exist preferentially in the lactam form, an important fact when considering the possible interactions of such hydroxylated metabolites with the soil matrix. Although the calculated bound-residue models in the present study only partly matched the experimental data, they were nevertheless useful in helping to interpret the experimental NMR results of a previous study. To get a better match between the calculated and the measured shifts of the side-chain nitrogens the calculations need to be further developed, taking into account the influence of neighbouring molecules in the solid state. Altogether, quantum chemical calculations are very helpful in the interpretation of NMR spectra. In the future, they can also be very useful for the prediction of NMR shifts, in particular when it is not possible to measure the metabolites due to a lack of material or in cases where practical experiments cannot be conducted. [source] Potential performance bottleneck in Linux TCPINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 11 2007Wenji Wu Abstract Transmission control protocol (TCP) is the most widely used transport protocol on the Internet today. Over the years, especially recently, due to requirements of high bandwidth transmission, various approaches have been proposed to improve TCP performance. The Linux 2.6 kernel is now preemptible. It can be interrupted mid-task, making the system more responsive and interactive. However, we have noticed that Linux kernel preemption can interact badly with the performance of the networking subsystem. In this paper, we investigate the performance bottleneck in Linux TCP. We systematically describe the trip of a TCP packet from its ingress into a Linux network end system to its final delivery to the application; we study the performance bottleneck in Linux TCP through mathematical modelling and practical experiments; finally, we propose and test one possible solution to resolve this performance bottleneck in Linux TCP. Copyright © 2007 John Wiley & Sons, Ltd. [source] Java implementation of policy-based bandwidth managementINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 4 2003S. Jha We describe a Java implementation of a policy based bandwidth management system using the standard policy protocols and an interface to the Linux Diffserv implementation. The useful features, such as extensibility and object orientation, of the Java implementation is illustrated by directly referring to the relevant programming codes. Through two practical experiments, we demonstrate the capability of our implementation in supporting policy-based dynamic resource allocations in enterprise networks.,Copyright © 2003 John Wiley &Sons, Ltd. [source] Message transmission using RF chaotic modulation-demodulation systemMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2005Hsi-Chiang Chou Abstract This paper describes a technique for transmitting information using a RF chaotic modulation,demodulation system. This system is composed of two parts: (i) a modulation,demodulation circuit, which is constructed using a chaotic Colpitts oscillator and (ii) an interface circuit, which is constructed using wideband OP and passive elements. The information is masked by adding a RF chaotic signal to be transmitted, and is obtained by subtraction of the chaotic signal at the receiver. The results of both practical experiments and simulations are presented to verify our approach. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 321,324, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20811 [source] Mixed-mode chromatography/isotope ratio mass spectrometry,RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 5 2010James S. O. McCullagh Liquid chromatography coupled to molecular mass spectrometry (LC/MS) has been a standard technique since the early 1970s but liquid chromatography coupled to high-precision isotope ratio mass spectrometry (LC/IRMS) has only been available commercially since 2004. This development has, for the first time, enabled natural abundance and low enrichment ,13C measurements to be applied to individual analytes in aqueous mixtures creating new opportunities for IRMS applications, particularly for the isotopic study of biological molecules. A growing number of applications have been published in a range of areas including amino acid metabolism, carbohydrates studies, quantification of cellular and plasma metabolites, dietary tracer and nucleic acid studies. There is strong potential to extend these to new compounds and complex matrices but several challenges face the development of LC/IRMS methods. To achieve accurate isotopic measurements, HPLC separations must provide baseline-resolution between analyte peaks; however, the design of current liquid interfaces places severe restrictions on compatible flow rates and in particular mobile phase compositions. These create a significant challenge on which reports associated with LC/IRMS have not previously focused. Accordingly, this paper will address aspects of chromatography in the context of LC/IRMS, in particular focusing on mixed-mode separations and their benefits in light of these restrictions. It aims to provide an overview of mixed-mode stationary phases and of ways to improve high aqueous separations through manipulation of parameters such as column length, temperature and mobile phase pH. The results of several practical experiments are given using proteogenic amino acids and nucleosides both of which are of noted importance in the LC/IRMS literature. This communication aims to demonstrate that mixed-mode stationary phases provide a flexible approach given the constraints of LC/IRMS interface design and acts as a practical guide for the development of new chromatographic methods compatible with LC/IRMS applications. Copyright © 2010 John Wiley & Sons, Ltd. [source] Inorganic Layers on Polymeric Films , Influence of Defects and Morphology on Barrier PropertiesCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 5 2003M. Hanika Abstract Flexible polymeric films are not only widely used in conventional packaging as substitute for glass and aluminum foil packaging but are also proposed as encapsulation for novel products, like flexible solar cells or organic light-emitting devices. The two essential properties of the polymeric packaging are flexibility and good permeation barrier properties against gases and vapors. This article deals with vacuum web coating as a common way of increasing barrier properties of polymeric films and the problems related to this procedure. Defects caused by particles and surface imperfections are found to dominate the permeation rate for such coated polymeric films. Atomic force microscopy, electron and also optical microscopy was used for analysis of the coating layer. Three-dimensional numerical simulations were performed for modeling of the influence of defect size, spacing and film thickness. Results of numerical modeling and of many practical experiments show that the permeability is almost independent of the substrate film thickness when a critical thickness is exceeded. In most cases the defects can be treated as independent of each other. The gas permeability of vacuum web-coated polymeric films can be quantitatively predicted by a simple formula. For gases, like oxygen, it is shown that a statistic analysis of the defect sizes by optical microscopy is sufficient. For water vapor transmission, however, the structure of the coating layer itself has also to be taken into account. [source] | |||||||||||||