Estimating materials parameters in thin-film BAW resonators using measured dispersion curves

The dispersion curves of Lamb-wave modes propagating along a multilayer structure are important for the operation of thin-film bulk acoustic wave (BAW) devices. For instance, the behavior of the side resonances that may contaminate the electrical response of a thin-film BAW resonator depends on the dispersion relation of the layer stack. Because the dispersion behavior depends on the materials parameters (and thicknesses) of the layers in the structure, measurement of the dispersion curves provides a tool for determining the materials parameters of thin films. We have determined the dispersion curves for a multilayer structure through measuring the mechanical displacement profiles over the top electrode of a thin-film BAW resonator at several frequencies using a homodyne Michelson laser interferometer. The layer thicknesses are obtained using scanning electron microscope (SEM) measurements. In the numerical computation of the dispersion curves, the piezoelectricity and full anisotropy of the materials are taken into account. The materials parameters of the piezoelectric layer are determined through fitting the measured and computed dispersion curves.     

Structural and Catalytic Properties of Alkyl-Substituted Phosphanes. Effect of Ortho-Modification on Rhodium-Catalyzed 1-Hexene Hydroformylation

The influence of the alkyl-substituted phosphanes (o-methylphenyl)diphenylphosphane (o-MeP), (o-ethylphenyl)diphenylphosphane (o-EtP), bis(o-methylphenyl)phenylphosphane (o-Me₂P), bis(o-ethylphenyl)phenylphosphane (o-Et₂P), and (2,4,5-trimethylphenyl)diphenylphosphane (2,4,5-MeP) was screened in model reaction of rhodium-catalyzed 1-hexene hydroformylation. Compared with PPh₃, the prepared phosphanes afforded lower chemoselectivity towards aldehydes, but increased the normal to branched ratio. Catalyst results are discussed in relation to stereoelectronic properties of the phosphane ligands. Electron donor capacity of the ligands was studied in terms of spectroscopic data of the trans-RhCl(CO)P₂ species, formed in reaction between Rh₂(-Cl)₂(CO)₄ and the ligands (P). Furthermore, steric attributes of free and bound phosphanes were investigated by Tolmans cone angle method. Crystal structures for ligands o-EtP, o-Me₂P, o-Et₂P, and complexes trans-Rh(CO)Cl(o-MeP)₂ and trans-Rh(CO)Cl(o-Et₂P) were solved as well.     

Polynomial Behavioural Modelling of Switched Capacitor Amplifiers

A data-based modeling technique for amplifiers in switched capacitor circuits is presented. The measured output settling error of a switched capacitor (SC) amplifier is presented as a two-dimensional polynomial of the initial voltages in the input and output nodes of the amplifier. This fitted polynomial can then be used as a very compact behavioral discrete-time model that can replicate also the output-dependent errors of the amplifier. The procedure is illustrated by characterizing an existing amplifier and using the fitted error model of it in behavioral simulations of a pipeline A/D converter.     

The influence of heat on the aroma of cloudberries (Rubus Chamaemorus L.)

Summary The qualitative and quantitative differences between the volatiles of fresh and heated cloudberries have been evaluated and the significance of the differences calculated. 14 new cloudberry volatiles have been identified, including vanillin, methyl vanillate, acetovanillone and 3,5-Dhydroxy-2-methyl-4Hpyran-4-one. During the heating procedure two additional compounds, 3-hydroxypyran-2-one and 2-pyrrolaldehyde, were formed. Comparison of the quantitative data for the heated and unheated samples revealed 21 compounds having significant differences in concentration at or below the 10% level. The concentration of 4-vinylphenol, 2-methoxy-5-vinylphenol, furfural, 5-hydroxymethylfurfural and 3,5-dihydroxy2-methyl-4H-pyran-4-one increased very markedly on heating. The concentrations of 81 compounds in the unheated press juice of cloudberries are given.

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Der Einfluß der Erhitzung auf das Aroma der Moltebeeren (Rubus chamaemorus L.)

Zusammenfassung Die Unterschiede zwischen den flüchtigen Stoffen des frischen und des erhitzten Saftes der Moltebeeren wurden qualitativ und quantitativ untersucht. Dabei wurden 14 neue Verbindungen aufgefunden, wie Vanillin, Vanillinsäuremethylester, Acetovanillon und 3,5-Dihydroxy-2-methyl-4-Hpyran-4-on. Während der Wärmebehandlung wurden zusätzlich 3-Hydroxypyran-2-on und 2-Pyrrolaldehyd gebildet. 21 Komponenten zeigten im unbehandelten und im erhitzten Saft deutliche Gehaltsunterschiede. Die Konzentrationen an 4-Vinylphenol, 2-Methoxy-5vinyl-phenol, Furfurol, 5-Hydroxymethylfurfurol und 3,5-Dihydroxy-2-methyl-4H-pyran-4-on stiegen während des Erhitzens stark an. Schließlich sind die Konzentrationen von 81 Stoffen im unbehandelten Saft angegeben.

     

Performance of receive diversity and LMMSE chip equalization in WCDMA HSDPA network

More advanced receiver structures than the conventional single antenna Rake can be used to improve the signal-to-noise (SNR) ratios, which is especially beneficial in order to utilize the high bit rates provided by the HSDPA concept in Wideband Code Division Multiple Access (WCDMA) network. In WCDMA system, orthogonal Walsh–Hadamard sequences are used as channelization codes. In frequency-selective fading channels the orthogonality of channelization codes disappears and intra-cell multiple access interference (MAI) arises. In order to mitigate the effect of MAI, chip-level equalization has shown to be a simple and effective solution. The effectiveness of chip equalization, however, degrades at the cell borders where the inter-cell interference dominates rather than MAI. Dual antenna reception is a straight-forward solution to mitigate that performance drop. In this paper, we present an analysis of the expected gains of advanced receivers over conventional single antenna Rake receiver in realistic situations by using a dynamic WCDMA system-level tool. Considered advanced receivers include single and dual antenna Linear Minimum Mean Squared Error (LMMSE) chip-level equalizers and dual antenna Rake receiver. The network performance with advanced receivers is studied also from a more practical point of view by assuming that the penetration of advanced HSDPA terminal receivers is gradually increased in the network.     

Effects of enzymically modified amylopectin on the rheological properties of amylose-amylopectin mixed gels

Branched α-dextrins with different molecular weights were prepared from waxy maize. A series of β-limit dextrins was prepared from α-dextrins and native amylopectin. The fine structure of the dextrin samples was investigated by debranching, and was found to be similar to the unit chain distribution of native amylopectin. The absolute molecular weights of α- and β-limit dextrins and commercial potato amy lose were determined by gel-permeation chromatography (GPC) and with a dual light-scattering detector. Solubilized potato amy lose and α- and β-limit dextrins were mixed at different ratios to give a total concentration of 8%. Dynamic viscoelastic measurements showed that gel formation of amylose was highly dependent both on the ratio of amylose to α-dextrin and on the molecular weight of α-dextrin. α-Dextrin caused an increase of storage modulus, G, when the amylose: α-dextrin ratio was low and the molecular weight of α-dextrin was high. The high-molecular-weight α-dextrin influenced amylose gelation in the same way as native waxy maize starch, but the medium- and low-molecular-weight α-dextrins weakened the gel formation, especially at a ratio of 25:75 (amylose: α-dextrin). When low-molecular-weight β-limit dextrins were mixed with amylose, the resulting gels were more rigid than those in which amylose was mixed with corresponding α-dextrins. When high-molecular-weight β-limit dextrins were mixed with amylose, the resulting gels were weaker.     

Effect of photocatalytic and hydrophobic coatings on brewery surface microorganisms

The aim of this study was to determine whether process hygiene in the beverage industry could be improved by applying new coating techniques to process surfaces. Photocatalytic titanium dioxide (TiO(2)) and hydrophobic coatings applied to stainless steel with or without added antimicrobial compounds were studied in laboratory attachment tests and in a 15-month process study. No clear reductions in numbers of attached microbes were obtained with photocatalytic coatings, except for coatings to which silver had been added. These TiO(2)+Ag coatings reduced microbial coverage in laboratory studies and in some process samples. Hydrophobic coatings reduced the area coverage of microorganisms in 4-h laboratory studies but did not affect colony counts in laboratory or process studies. The surfaces had changed from hydrophobic into hydrophilic during the process study. The coatings did not mechanically fully withstand process conditions; part of the hydrophobic coatings had peeled off, most of the precipitated Ag had dissolved, and some of the TiO(2) coatings were damaged. In conclusion, functional coatings have potential for reducing microbial loads on beverage industry surfaces, but these coatings need further development.