Recent advances in high-power industrial applications

The industrial electronics market is continuously changing following the users demand. This paper introduces the current industrial electronics applications and is focused in the medium-voltage high-power ones. The multilevel approach is the most attractive solution to achieve the challenges that medium voltage-high power applications arise. Several commercial examples are introduced and some of the last research advances related to multilevel power electronic converters are presented in this paper

New trends and topologies for high power industrial applications: The multilevel converters solution

This paper reviews briefly the current scenarios where power electronics converters are being applied. In the paper, the main focus moves towards the high power applications, reviewing the different alternatives and topologies. The multilevel approach is studied in more depth, showing that is a good solution to the challenges that medium voltage-high power applications pose. Several industry examples are introduced and the most suitable modulation techniques for multilevel high power converters are explained. Among them, the recent selective harmonic mitigation method appears as a good solution to achieve a high performance. Finally the conclusions are addressed

Tetracycline-resistance encoding plasmids from Paenibacillus larvae, the causal agent of American foulbrood disease, isolated from commercial honeys

Paenibacillus larvae, the causal agent of American foulbrood disease in honeybees, acquires tetracycline-resistance via native plasmids carrying known tetracycline-resistance determinants. From three P. larvae tetracycline-resistant strains isolated from honeys, 5-kb-circular plasmids with almost identical sequences, designated pPL373 in strain PL373, pPL374 in strain PL374, and pPL395 in strain PL395, were isolated. These plasmids were highly similar (99%) to small tetracycline-encoding plasmids (pMA67, pBHS24, pBSDMV46A, pDMV2, pSU1, pAST4, and pLS55) that replicate by the rolling circle mechanism. Nucleotide sequences comparisons showed that pPL373, pPL374, and pPL395 mainly differed from the previously reported P. larvae plasmid pMA67 in the oriT region and mob genes. These differences suggest alternative mobilization and/or conjugation capacities. Plasmids pPL373, pPL374, and pPL395 were individually transferred by electroporation and stably maintained in tetracycline-susceptible P. larvae NRRL B-14154, in which they autonomously replicated. The presence of nearly identical plasmids in five different genera of gram-positive bacteria, i.e., Bhargavaea, Bacillus, Lactobacillus, Paenibacillus, and Sporosarcina, inhabiting diverse ecological niches provides further evidence of the genetic transfer of tetracycline resistance among environmental bacteria from soils, food, and marine habitats and from pathogenic bacteria such as P. larvae. [Int Microbiol 2014; 17(1):49-61]Keywords: American foulbrood disease (AFB) · Paenibacillus larvae · tetracycline resistance · plasmids · honeybee

Feasibility analysis and performance evaluation and optimization of a DXSAHP water heater based on the thermal capacity of the system: a case study

The present work conducts an evaluation of the feasibility and the overall performance and consequent optimization of a direct expansion solar assisted heat pump (DXSAHP) employed for domestic water heating. For the study conducted R134a, R404A, R407C and R410A working fluids were evaluated as well as the use of four, six and eight flat-plate solar collectors and a worktime ranging from 1 to 6 h. The case study is based in Mexico City with a 300 L container and a hot water outlet temperature of 51 °C. The paper introduces a new evaluation criterion based on the thermal capacity and all the evaluations conducted throughout this research revolve around this performance metric. The results show that, the system would require at least 4 h of operation to achieve the outlet temperature. Additionally, it was found that the R410A refrigerant has the best heat transfer properties; with an average condensation heat rate of 6.31 kW, followed by the R407C with 5.72 kW, the R404A with 5.42 kW and the R134a with 5.18 kW. Diversely, the R134a refrigerant requires 0.402 kW of compression work, 62% less than the R410A, which requires 1.06 kW. Consequently, R134a delivers the highest COP, which ranges from 7 to 14, followed by the R407C and R404A refrigerants, which present a similar behaviour between them, with COP ranging from 5 to 9 and 4 to 8, respectively, and finally the R410A, achieving the lowest COP, ranging from 3.5 to 6.5. Moreover, it was found that the R134a presents a higher dispersion regarding the energy exchange rate, which reveals that it is the fluid most susceptible to external factors, such as the weather. Contrarily, the remaining refrigerants present a more consistent performance. Finally, the optimization revealed that the R407C refrigerant is the most suitable given that it requires 20% less compression work than the R404A. This provides the heat pump system with a steadier behaviour, a COP ranging from 7 to 8, 30% higher than R410A, a worktime decrease of 1.5 h and heat transfer area of 5.5 flat-plate solar collectors, equivalent to a 31% reduction, both compared to R134a.The research work described in this paper was fully supported by the grants from the National Council ofScience and Technology of Mexico and the resources provided by the Applied Thermal and Hydraulic EngineeringLaboratory of the National Polytechnic Institute of Mexico.Peer ReviewedPostprint (published version

Conventional Space-Vector Modulation Techniques versus the Single-Phase Modulator for Multilevel Converters

Space-vector modulation is a well-suited technique to be applied to multilevel converters and is an important research focus in the last 25 years. Recently, a single-phase multilevel modulator has been introduced showing its conceptual simplicity and its very low computational cost. In this paper, some of the most conventional multilevel space-vector modulation techniques have been chosen to compare their results with those obtained with single-phase multilevel modulators. The obtained results demonstrate that the single-phase multilevel modulators applied to each phase are equivalent with the chosen wellknown multilevel space-vector modulation techniques. In this way, single-phase multilevel modulators can be applied to a converter with any number of levels and phases avoiding the use of conceptually and mathematically complex space-vector modulation strategies. Analytical calculations and experimental results are shown validating the proposed concepts

A symmetrical dirhenium(I) complex with 4,4''-azobis(2,2'-bipyridine) as a bridging ligand: Synthesis, physicochemical properties and applications in detection of biologically relevant thiols and in chemotherapy for bone cancer

A new dinuclear complex of formula [{Re(CO)3(py)}2(μ-4,4”-azobpy)](PF6)2, with py = pyridine and 4,4”-azobpy = 4,4”-azobis(2,2'-bipyridine), has been synthesized and characterized by spectroscopic and electrochemical techniques. The symmetrical nature of the dimetallic cation has been confirmed by nuclear magnetic resonance (NMR) measurements. When adding L-cysteine or L-glutathione, large and rapid changes in its UV-Vis absorption spectra were observed, which can be used for detecting both biologically relevant thiols. A promising activity for using this complex as a chemotherapeutic agent for bone cancer was also disclosed. Quantum mechanical calculations supported the experimental data.Fil: Abate, Pedro Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; ArgentinaFil: Sottile, Marco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: León, Ignacio E.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Vergara, Mónica M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; ArgentinaFil: Katz, Néstor Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentin

Two-dimensional modulation technique with dc voltage control for single-phase two-cell cascaded converters

In this paper, a simple feed-forward modulation technique for single-phase two-cell multilevel cascaded converters is presented. All the possible switching states of the power converter are taken into account applying a two dimensional control region. The proposed technique uses the actual values of the DC-Link capacitor voltages to obtain output phase voltages and currents with low harmonic distortion with any dc voltage in the H-bridges of the cascaded converter. The possible switching sequences of the converter are studied and, depending on the actual dc voltage values, their desired values are achieved. Simulation results are shown in order validate the proposed technique working as a synchronous rectifier

Comparison between FS-MPC control strategy for an UPS inverter application in α-β and abc frames

The voltage source inverter (VSI) of an uninterruptible power supply (UPS) is a system where the main objective is to obtain a high quality output sinusoidal voltage with independence on the output load. For this reason, it includes an output LC filter. The presence of the filter increases the complexity of the controller design thus it is necessary to evaluate the performance of the control strategy in terms of the output voltage quality and computational cost of the algorithm. In this paper, both analysis are developed for the finite states model predictive control (FS-MPC) of a VSI performed in the abc and α-βframes. Both algorithms are summarized and compared in order to establish an objective criteria to choose among them when a hardware implementation is developed. Simulation results are presented for both algorithms to validate the analysis

Algoritmo de modulación vectorial para convertidores multinivel de cuatro ramas utilizando coordenadas naturales

SEMINARIO ANUAL DE AUTOMÁTICA, ELECTRÓNICA INDUSTRIAL E INSTRUMENTACIÓN. SAAEI 2005 (.2005.SANTANDER, ESPAÑA)En este trabajo se presenta el primer algoritmo de modulación vectorial tridimensional para convertidores multinivel de cuatro ramas. Este convertidor se puede aplicar en el campo de los filtros activos o a los compensadores de corriente por el neutro para compensación de armónicos y corriente homopolar usando coordenadas naturales. Esta técnica simplifica en gran medida la selección del espacio tridimensional donde se encuentra un vector de tensión dado. El algoritmo reduce drásticamente la complejidad computacional y los cálculos para determinar los vectores activos con sus correspondientes tiempos que generan el vector de referencia de tensión. Además, la baja carga computacional del algoritmo propuesto es siempre la misma y es independiente del número de niveles del convertidor

Mononuclear Pd(II) and Pt(II) complexes with an α-N-heterocyclic thiosemicarbazone: Cytotoxicity, solution behaviour and interaction: Versus proven models from biological media

Two Pd(ii) and Pt(ii) complexes with two pyrrol-2-carbaldehyde N-p-chlorophenylthiosemicarbazone ligands are designed and characterized showing mononuclear structures. An important pharmacological property for both compounds is the high selectivity for tumor cells and a lack of activity in healthy cells. The Pd(ii) compound shows a higher antitumor activity and selectivity than the Pt(ii) compound. Both complexes present a variety of biological interactions: with DNA models (pBR322 and CT DNA), proteins (lysozyme and RNase) and other biological targets like proteosome. Our results show that the Pd(ii) complex is a more interesting candidate for potential anticancer therapies than the Pt(ii) complex, and we provide new insight into the design and synthesis of palladium compounds as potential antitumor agents.This work was supported by the following grants for the Spanish MINECO: SAF-2012-34424, CTQ2015-68779R and CTQ2015-70371-RED