There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

This International Myeloma Working Group consensus updates the disease defi nition of multiple myeloma to include validated biomarkers in addition to existing requirements of attributable CRAB features (hypercalcaemia, renal failure, anaemia, and bone lesions). These changes are based on the identifi cation of biomarkers associated with near inevitable development of CRAB features in patients who would otherwise be regarded as having smouldering multiple myeloma. A delay in application of the label of multiple myeloma and postponement of therapy could be detrimental to these patients. In addition to this change, we clarify and update the underlying laboratory and radiographic variables that fulfi l the criteria for the presence of myeloma-defi ning CRAB features, and the histological and monoclonal protein requirements for the disease diagnosis. Finally, we provide specifi c metrics that new biomarkers should meet for inclusion in the disease defi nition. The International Myeloma Working Group recommends the implementation of these criteria in routine practice and in future clinical trials, and recommends that future studies analyse any diff erences in outcome that might occur as a result of the new disease defi nition.

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International Myeloma Working Group updated criteria for the diagnosis of multiple myeloma.

Solid-state switch-mode rectification converters have reached a matured level for improving power quality in terms of power-factor correction (PFC), reduced total harmonic distortion at input AC mains and precisely regulated DC output in buck, boost, buck-boost and multilevel modes with unidirectional and bidirectional power flow. This paper deals with a comprehensive review of improved power quality converters (IPQCs) configurations, control approaches, design features, selection of components, other related considerations, and their suitability and selection for specific applications. It is targeted to provide a wide spectrum on the status of IPQC technology to researchers, designers and application engineers working on switched-mode AC-DC converters. A classified list of more than 450 research publications on the state of art of IPQC is also given for a quick reference.

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A review of single-phase improved power quality AC-DC converters

Light-Emitting Diodes. (Monographs in Electrical and Electronic Engineering.) By A. A. Bergh and P. J. Dean. Pp. viii+591. (Clarendon: Oxford; Oxford University: London, 1976.) £22.

/pdf/light-emitting-diodes-ubzde6g9qc.pdf

Light-emitting diodes

Solid-state switch mode AC-DC converters having high-frequency transformer isolation are developed in buck, boost, and buck-boost configurations with improved power quality in terms of reduced total harmonic distortion (THD) of input current, power-factor correction (PFC) at AC mains and precisely regulated and isolated DC output voltage feeding to loads from few Watts to several kW. This paper presents a comprehensive study on state of art of power factor corrected single-phase AC-DC converters configurations, control strategies, selection of components and design considerations, performance evaluation, power quality considerations, selection criteria and potential applications, latest trends, and future developments. Simulation results as well as comparative performance are presented and discussed for most of the proposed topologies.

Comprehensive Study of Single-Phase AC-DC Power Factor Corrected Converters With High-Frequency Isolation

In this paper electrical models of low power metal halide and high pressure sodium lamps are presented, which are compatible with the Pspice program. By means of an exhaustive characterization of several lamps of different manufacturers and powers, operated at high frequency, simple expressions are obtained in order to simplify the lamp modeling. Experimental and simulation results are presented in order to verify the models presented for their application in electronic ballast design for these kind of lamps.

https://ieeexplore.ieee.org/iel5/8625/27324/01216665.pdf

Modeling of low power metal-halide and HPS lamps operated at high frequency

This paper presents a dimmable electronic ballast for T5 fluorescent lamp. A modified dimming method is proposed based on variable DC bus and dedicated IR21592 IC. A combined method of dc link voltage control of resonant inverter, and a fixed phase angle of resonant inverter that is kept constant using the phase-locked loop (PLL) is employed. The electrodes heating is evaluated in order to guarantying the correct lifetime of T5 fluorescent lamp using Sum of Squares (SoS) method. Simulation, mathematical analysis, and experimental results with IR21592 IC were demonstrated for different operation conditions.

Voltage-frequency control dimming method for T5 fluorescent lamps

In this paper a new solution to implemented single-stage high-power-factor electronic ballast based on integrated buck DC-DC converter and a half-bridge resonant inverter is presented. The buck converter is operated in discontinuous conduction mode and at constant frequency providing an input power factor high enough to satisfy present standard requirements. The operation of the proposed ballast is also investigated in detail in this paper. A ballast prototype for 2/spl times/36 W fluorescent lamps has been simulated and implemented at the laboratory.

http://ieeexplore.ieee.org/iel5/7171/19288/00891413.pdf

A novel HPF electronic ballast based on integrated buck half bridge resonant inverter

This paper presents the analysis and design methodology for a LLC resonant converter controlled using two different control methods, switching frequency and VI (Variable Inductor). In order to compare both control techniques a battery charger is analyzed and simulation results are presented. In order to control the converter gain, the converter is regulated in the first case by varying the switching frequency and, in the second case, is regulated through a variable resonant tank. The design methodology is presented and simulation results were obtained and compared with the theoretical ones considering a simple battery charger application.

Analysis and simulation of the LLC resonant converter under different control methods

In this paper a methodology to modeling high-power-factor (HPF) ac-dc converters in LED driving applications is presented. The proposed methodology is based on the averaging methodology applied to the converter under modeling. An averaged large-signal equivalent circuit is generated in this manner, which will be useful to perform extremely fast computer simulations. From the large-signal model both steady-state and small-signal analysis can be carried out to completely modeling the converter, achieving any desired steady-state characteristic and small-signal transfer functions. The proposed methodology is very intuitive and allows designers to achieve a natural understanding of the LED driver performance. The modeling procedure is illustrated with a HPF buck-boost converter operating in discontinuous conduction mode (DCM) designed to supply a 70W LED lamp. Simulation and experimental results demonstrate the validity of the proposed methodology.

J.M. Alonso

Papers

Modeling of low power metal-halide and HPS lamps operated at high frequency

Voltage-frequency control dimming method for T5 fluorescent lamps

A novel HPF electronic ballast based on integrated buck half bridge resonant inverter

Analysis and simulation of the LLC resonant converter under different control methods

Modeling single-stage high-power-factor AC-DC converters for LED driving applications