Controlled-resistance loads for induction heating applications using thin non-magnetic metallic layers

The design of controlled-resistance loads for domestic induction heating applications using thin non-magnetic conductive layers is described. Thin metallic layers are fabricated using the phase vapour deposition technique. Such layers would enable vessels, the inductive behaviour of which was similar to those fabricated with conventional ferromagnetic bulk materials, to be manufactured. Optimum layer thickness is investigated using an analytical impedance model of the complete induction system     

Reactivity of pyrrole pigments,part 15: On the oxidation of bilirubins and biliverdins

Summary Characteristic oxidation reactions of bilin-1,19-diones (biliverdins) and biladien-ac-1,19-diones (bilirubins) were reinvestigated. These include bromine and iodine oxidation of biliverdin IX, bilirubin IX and their Zn(II) complexes, the reaction described by Siedel (1941) of mesobilirubin XIII dimethyl ester with nitric acid (Gmelin reaction) and Smith's oxidation (1977) of etiobiliverdin IV using Tl triacetate and Pb tetra-acetate. For some of these reaction products new structures were assigned on the basis of their spectrometric data. These structures agreed with the expected reactivity pattern of biliverdins and bilirubins.

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Reaktivität von Pyrrolpigmenten, 15 Mitt.: Über die Oxidation von Bilirubinen und Biliverdinen

Zusammenfassung Einige bekannte Oxydationen von Bilin-1,19-dionen (Biliverdinen) und Biladien-ac-dionen (Bilirubinen) wurden neuerlich untersucht, und zwar die Brom- und Jodoxydation von Biliverdin IX und Bilirubin IX sowie der entsprechenden Zn(II)-Komplexe, die Reaktion des Dimethylesters von Mesobilirubin XIII mit HNO₃ (Gmelinreaktion; Siedel 1941) und Smith's Oxydation von Etiobiliverdin IV mit Thaliumtriacetat und Bleitetraacetat. Für einige Reaktionsprodukte wurden aufgrund spektroskopischer Daten neue Strukturen-konsistent mit dem bekannten Reaktionsverhalten von Biliverdinen und Bilirubinen-formuliert.

     

Three‐dimensional Arrangement of Short DNA Oligonucleotides at Surfaces via the Synthesis of DNA‐branched Polyacrylamide Brushes by SI‐ATRP

Short DNA oligonucleotide branches are incorporated into acrylamide brushes via surface initiated atom transfer radical polymerization in an attempt to increase DNA surface density by building three‐dimensional molecular architectures. ATR‐FTIR as well as hybridization studies followed by SPR confirm the incorporation of the DNA sequences into the polymer backbone. MALDI‐TOF analysis further suggests that six acrylamide monomer units are typically separating DNA branches present on a single brushes approximately 26 units long. This new approach offers a promising alternative to SAM‐based nucleic acid and aptamer sensors and could enable the realization of more complex soft materials of controlled architecture capable of both recognition and signaling by including additional optically or electrochemically active moieties.

     

Efficiency optimization in ZVS series resonant inverters with asymmetrical voltage-cancellation control

This paper presents a time-domain analysis and a computerized search algorithm for optimizing the efficiency in zero-voltage switching (ZVS) full-bridge series resonant inverters with asymmetrical voltage-cancellation (AVC) control for different load quality factors. The optimum AVC control found allows all the switches to be turned on with zero voltage with the minimum switching frequency. In order to minimize losses, the switching frequency is kept as close as possible to resonance. The optimum AVC control is compared with previous fixed or narrow frequency range control strategies to show that it improves performance over all the output power range for different loads. The detailed steady-state analysis carried out here increases the precision of the first-harmonic analysis of a previous work, which is especially important with distorted output currents due to low load quality factors or highly asymmetrical modulation strategies. The theoretical results are verified experimentally.     

Versatile High-Frequency Inverter Module for Large-Signal Inductive Loads Characterization Up to 1.5 MHz and 7 kW

This paper presents the challenges encountered and the solutions adopted during the construction of a versatile voltage-fed high-frequency series-resonant half-bridge inverter module. It is used in the large-signal power generator of an inductive load characterization test-bench operating from 1 kHz up to 1.5 MHz and up to 7-kW output power for a variety of loads. Square wave operation of the module is established slightly above resonance under zero voltage switching conditions. Output power is controlled by means of a variable dc bus while resonant conditions are fixed by means of two adjustable capacitor banks. The control of every test-bench block and the triggering waveform generation is performed digitally with a field programmable gate array. Two prototype modules have been designed, constructed and evaluated for operation in half-bridge and full-bridge configurations showing rugged and stable operation under hazardous conditions such as voltage transients as high as dv/dt = 50 kV/mus at 1 MHz during the characterization of domestic induction heating loads.     

Search for a dark matter annihilation signal from the galactic center halo with H.E.S.S

A search for a very-high-energy (VHE; ≥100 GeV) γ-ray signal from self-annihilating particle dark matter (DM) is performed towards a region of projected distance r～45-150 pc from the Galactic center. The background-subtracted γ-ray spectrum measured with the High Energy Stereoscopic System (H.E.S.S.) γ-ray instrument in the energy range between 300 GeV and 30 TeV shows no hint of a residual γ-ray flux. Assuming conventional Navarro-Frenk-White and Einasto density profiles, limits are derived on the velocity-weighted annihilation cross section (σv) as a function of the DM particle mass. These are among the best reported so far for this energy range and in particular differ only little between the chosen density profile parametrizations. In particular, for the DM particle mass of ～1 TeV, values for (σv) above 3×10(-25) cm(3)?s(-1) are excluded for the Einasto density profile.     

An introduction to voice search

Voice search is the technology underlying many spoken dialog systems (SDSs) that provide users with the information they request with a spoken query. The information normally exists in a large database, and the query has to be compared with a field in the database to obtain the relevant information. The contents of the field, such as business or product names, are often unstructured text. This article categorized spoken dialog technology into form filling, call routing, and voice search, and reviewed the voice search technology. The categorization was made from the technological perspective. It is important to note that a single SDS may apply the technology from multiple categories. Robustness is the central issue in voice search. The technology in acoustic modeling aims at improved robustness to environment noise, different channel conditions, and speaker variance; the pronunciation research addresses the problem of unseen word pronunciation and pronunciation variance; the language model research focuses on linguistic variance; the studies in search give rise to improved robustness to linguistic variance and ASR errors; the dialog management research enables graceful recovery from confusions and understanding errors; and the learning in the feedback loop speeds up system tuning for more robust performance. While tremendous achievements have been accomplished in the past decade on voice search, large challenges remain. Many voice search dialog systems have automation rates around or below 50% in field trials.