Results 271 to 280 of about 57,713 (310)

Transformation of plasmid DNA into Streptomyces at high frequency

Nature, 1978
OVER 60% of known antibiotics1 are produced by Streptomyces species, including many substances with valuable clinical and other applications; they therefore have considerable medical, biological and commercial importance. Although the process of gene exchange mediated by conjugation within these actinomycetes is apparently widespread2, the transfer of ...
M J, Bibb, J M, Ward, D A, Hopwood
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High frequency models of PCB-based transformers

Proceedings of the 44th IEEE 2001 Midwest Symposium on Circuits and Systems. MWSCAS 2001 (Cat. No.01CH37257), 2002
An equivalent network of PCB-based transformers with two windings is presented for use at high frequency (some MHz). After raising some criticisms to the traditional high frequency transformer model, a systematic procedure is presented to deduce the inductive and the capacitive coupling model of a two windings transformer.
ARTURI, CESARE MARIO, GANDELLI, ALESSANDRO   +1 more
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Transformer model for high frequencies

IEEE Transactions on Power Delivery, 1988
A method for the development of a high-frequency transformer model for use in an electromagnetic transient program (EMTP) is discussed. A transformer to be modeled is measured, and the results are used to calculate the transfer and admittance functions. Modal analysis is used to determine a no-load network model that can be used in the EMTP.
openaire   +1 more source

A new type high frequency transformer

IEEE Transactions on Magnetics, 1991
In order to realize small power supplies, the authors propose a type of coreless high-frequency transformer. This transformer is composed of simple twisted coils and its operating principle is based on the skin effect of current carrying conductors. Approximate analysis based on the symmetrical current distributions in each of the coil axes has been ...
S. Hayano, Y. Nakajima, H. Saotome, Y. Saito   +3 more
openaire   +1 more source

High-frequency investigation of planar transformers

2014 International Conference on Electrical Sciences and Technologies in Maghreb (CISTEM), 2014
Planar transformers are a novel type of devices used in integrated power systems. Having many advantages compared to classic wire wound technology; it's used to minimize size and weight and to increase their ability to withstand mechanical vibrations.
Aymen Ammouri, Hamed Belloumi, Tarek Ben Salah, Ferid Kourda   +3 more
openaire   +1 more source

High-Voltage, High-Frequency Transformer Design

2012
Conversion of AC mains voltages to a high-voltage (>10 kV), high-power (>10 kW) DC level is a key area of technology which is a requirement in many industrial processes, for example, in particulate emission control using electrostatic precipitators. In the majority of cases, this high-voltage DC requirement is achieved with a singlephase AC regulator ...
Paul Lefley, Philip Devine
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High–Frequency Transformation of Penicillium Chrysogenum

Nature Biotechnology, 1987
We report high–frequency transformation of penicillin–producing strains of Penicillium chrysogenum using plasmid vectors carrying the pyr4 gene of Neurospora crassa. Transformation to stable uracil independence is associated with acquisition of transforming DNA in high molecular forms that are not simple multimers of the vector.
J. M. Cantoral, B. Díez, J. L. Barredo, E. Alvarez, J. F. Martín   +4 more
openaire   +1 more source

Propagation of high frequency overvoltages in transformers

2014 ICHVE International Conference on High Voltage Engineering and Application, 2014
In modern grids and networks more and more switching and reconfiguration operations are present. In addition external stresses like lightning may cause overvoltages. Thus, such transients may subject the electric insulation system of power equipment.
M. Florkowski, P. Klys, J. Furgal, M. Kuniewski   +3 more
openaire   +1 more source

High-Frequency Impedance Transformations

2010
Active devices such as transistors or Op-Amps have bandwidth limitations that can result in instability or undesirable dynamic response in feedback circuits. As gain decreases with frequency, feedback-amplifier port-resistance values also change and effectively become reactive. These bandwidth-related reactances can resonate with other circuit elements.
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Analysis of high-frequency resistance in transformers

20th Annual IEEE Power Electronics Specialists Conference, 2003
An accurate, analytical method is proposed for calculating the lead and winding high-frequency resistance of complex transformer constructions. High-frequency resistance is derived from the resulting matrix system equations, common to the leads and windings. The effect of eddy currents in the leads is confirmed by theoretical results.
K. Sakakibara, N. Murakami
openaire   +1 more source