Comparative Analysis of Multilevel Converters for Medium-Voltage Applications

The electric energy demand has been steadily growing during the last century, and all forecasts indicate that it will keep growing in the following years. Within this frame, and due to all the problems that this demand increase generate in the environment, it is necessary improving the current techniques of electric energy conversion and transmission in order to increase the whole system efficiency. On the other hand, it is also necessary increasing the renewable energy resources exploitation through more efficient generation systems. According to these lines, the power electronics systems that have been installed in the last decades allowed to obtain better efficiency from the renewable natural resources like the wind or the solar power. These systems have also notably improved the quality of the power supplied, reducing the losses through what are known as power quality applications. Power converters are currently essential in any power electronics system. Within them, the multilevel converters specially suppose a breakthrough compared with the classical two level converters, as they allow obtaining voltage and current signals with lower harmonic content, what means fewer losses in high power medium voltage applications. In this Thesis a comparative study of some multilevel converter topologies normally used in high power medium voltage applications is done. The objective is analyzing in detail each topology and comparing it with the rest following different criteria, with the aim to know the advantages and drawbacks of each one and to realize which one is more suitable for each application

Viilun jatkoslinjan käyttöasteen tehostaminen

Tämän opinnäytetyön tarkoituksena oli kartoittaa käyntihäiriötekijöitä Joensuun vaneritehtaan viilu- ja liimausosastolla sijaitsevalla viilun jatkoslinjalla. Tavoitteena oli selvittää viilun jatkoslinjalla häiriötekijät, jotka huononsivat linjan käyttöastetta. Käyttöasteella tarkoitetaan vanerin valmistusprosessissa sitä, kuinka suuren osan kokonaiskäyntiajasta kone toimii tehollisesti. Tutkimusosiossa seurasin prosessin kulkua ja kirjasin ylös linjalla tapahtuneet häiriöt, niiden syyt ja kestoajat. Seurasin myös operaattorin toimintaa kirjaten ylös operaattorin toimet ja niihin käytetyn ajan. Seurantatulokset listasin tapahtuma – ja häiriöaikakaavakkeelle. Tutkimuksen avulla sain selville linjan toiminnassa eniten aikaa vievät häiriötekijät, jotka alensivat sen käyttöastetta. Tutkimuksia analysoimalla pyrin selvittämään suurimmat ongelmat linjalla, minkä pohjalta kehitin erilaisia kehitysideoita. Tuloksia tarkastellaan diagrammeina

A regulative proposal of student-life balance in Higher Education

La conciliación estudiantil-familiar es el derecho que garantiza un equilibrio entre el cumplimiento de las obligaciones académicas y las responsabilidades familiares. En los actuales planes de estudio universitarios, el requisito de cumplir un número determinado de créditos presenciales así como otras medidas implantadas con el Espacio Europeo de Educación Superior, suponen una problemática para el alumnado que necesita compaginar la maternidad o la paternidad con su formación. En esta investigación, a través de una metodología cualitativa basada en el análisis de contenido documental, revisamos los diferentes estudios internacionales que indagan sobre los recursos, las políticas y las líneas de actuación que posibilitan esta conciliación en el contexto de la Educación Superior; así como la información contenida en las páginas web de diversas instituciones universitarias nacionales e internacionales. Los resultados demuestran que las Instituciones universitarias españolas no plantean normativas o acciones concretas, poniendo de manifiesto la ausencia de un marco legal que sustente y garantice la conciliación estudiantil-familiar en el ámbito universitario. A modo de conclusión, proponemos algunas medidas reguladores como auténticas oportunidades de igualdad que eviten las situaciones discriminatorias.The student-life balance is the right that guarantees the equilibrium between ensuring the fulfillment of academic obligations and family responsibilities. In the current university curricula, the requirement to fulfill a certain number of classroom credits and other measures implemented by the European Space of Superior Education, pose a problem for students who need to reconcile parenthood with their training. In this research, we use a qualitative methodology based on the analysis of documentary content. We review the different international studies that investigate the resources, policies and lines of action that enable this balance in the context of Higher Education. And we discuss the information contained in the websites of various national and international universities. The results show that Spanish universities do not offer policies or concrete actions, highlighting the absence of a legal framework to support and ensure the student-life balance at university. To conclude, we propose some regulatory measures, as genuine equal options, to avoid discriminatory situations

Reconfiguration Algorithm to Reduce Power Losses in Offshore HVDC Transmission Lines

The race to increase the efficiency and reduce the power losses in transmission systems has resulted in the substantial growth of high-voltage direct current (HVDC) transmission systems. Moreover, the interconnection of these transmission systems significantly increases their reliability. However, the control of these meshed grids is a key problem that usually is managed through the control of the VSCs in those grids, but the control of the VSC can be complemented with a reconfiguration algorithm. This paper proposes the use of the particle swarm optimization algorithm, in order to reconfigure meshed HVDC transmission systems and reduce losses. The proposed algorithm has been tested in the CIGRE benchmark grid, which comprises of several offshore wind farms that generate energy sent to the grid through several HVDC transmission lines. The results show that as the energy generation changes due to wind changes, the grid topology must be reconfigured in order to achieve the maximum efficiency. Doing this reconfiguration, power savings around 18–19% could be achieve

NWCSAF High Resolution Winds (NWC/GEO-HRW) Stand-Alone Software for Calculation of Atmospheric Motion Vectors and Trajectories

The High Resolution Winds (NWC/GEO-HRW) software is developed by the EUMETSAT Satellite Application Facility on Support to Nowcasting and Very Short Range Forecasting (NWCSAF). It is part of a stand-alone software package for the calculation of meteorological products with geostationary satellite data (NWC/GEO). NWCSAF High Resolution Winds provides a detailed calculation of Atmospheric Motion Vectors (AMVs) and Trajectories, locally and in near real time, using as input geostationary satellite image data, NWP model data, and OSTIA sea surface temperature data. The whole NWC/GEO software package can be obtained after registration at the NWCSAF Helpdesk, www.nwcsaf.org, where users also find support and help for its use. NWC/GEO v2018.1 software version, available since autumn 2019, is able to process MSG, Himawari-8/9, GOES-N, and GOES-R satellite series images, so that AMVs and trajectories can be calculated all throughout the planet Earth with the same algorithm and quality. Considering other equivalent meteorological products, in the ‘2014 and 2018 AMV Intercomparison Studies’ NWCSAF High Resolution Winds compared very positively with six other AMV algorithms for both MSG and Himawari-8/9 satellites. Finally, the Coordination Group for Meteorological Satellites (CGMS) recognized in its ‘2012 Meeting Report’: (1) NWCSAF High Resolution Winds fulfills the requirements to be a portable stand-alone AMV calculation software due to its easy installation and usability. (2) It has been successfully adopted by some CGMS members and serves as an important tool for development. It is modular, well documented, and well suited as stand-alone AMV software. (3) Although alternatives exist as portable stand-alone AMV calculation software, they are not as advanced in terms of documentation and do not have an existing Helpdesk

The modular network structure of the mutational landscape of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is associated with the sequential accumulation of acquired genetic alterations. Although at diagnosis cytogenetic alterations are frequent in AML, roughly 50% of patients present an apparently normal karyotype (NK), leading to a highly heterogeneous prognosis. Due to this significant heterogeneity, it has been suggested that different molecular mechanisms may trigger the disease with diverse prognostic implications. We performed whole-exome sequencing (WES) of tumor-normal matched samples of de novo AML-NK patients lacking mutations in NPM1, CEBPA or FLT3-ITD to identify new gene mutations with potential prognostic and therapeutic relevance to patients with AML. Novel candidate-genes, together with others previously described, were targeted resequenced in an independent cohort of 100 de novo AML patients classified in the cytogenetic intermediate-risk (IR) category. A mean of 4.89 mutations per sample were detected in 73 genes, 35 of which were mutated in more than one patient. After a network enrichment analysis, we defined a single in silico model and established a set of seed-genes that may trigger leukemogenesis in patients with normal karyotype. The high heterogeneity of gene mutations observed in AML patients suggested that a specific alteration could not be as essential as the interaction of deregulated pathways

Viral Disease in Lagomorphs: A Molecular Perspective

Our understanding of molecular biology of the viruses that infect lagomorphs is largely limited to the leporipoxvirus myxoma virus (MYXV) and the lagoviruses rabbit haemorrhagic disease virus (RHDV) and European brown hare syndrome virus (EBHSV) that infect the European rabbit (Oryctolagus cuniculus) and the European brown hare (Lepus europaeus) respectively. Thanks to the great effort of historic surveillance studies and careful sample archiving, the molecular evolution of these viruses is being resolved. Although historically considered viruses that cause species specific diseases recent reports show that several lagomorphs may now face the threat of these maladies. The driving factors behind these changes has not been determined and the effect of these species jumps on lagomorph populations has yet to be seen. Lagomorphs are also affected by several other lesser studied viral diseases. In addition, recent metagenomic studies have led to the identification of novel lagomorph viruses the importance of these to lagomorph health remains to be fully determined. In this chapter we summarize molecular aspects of viruses that infect lagomorphs, paying particular attention to recent interspecies infections

CYP2C8 gene polymorphism and bisphosphonate-related osteonecrosis of the jaw in patients with multiple myeloma

Osteonecrosis of the jaw is an uncommon but potentially serious complication of bisphosphonate therapy in multiple myeloma. Previous studies showed that the presence of one or two minor alleles of the cytochrome P450, subfamily 2C polypeptide 8 gene (CYP2C8) polymorphism rs1934951 was an independent prognostic marker associated with development of osteonecrosis of the jaw in multiple myeloma patients treated with bisphosphonates. The aim of this study was to validate the frequency of SNP rs193451 in 79 patients with multiple myeloma. In 9 (22%) patients developing osteonecrosis of the jaw, a heterozygous genotype was found, in contrast with those who did not develop osteonecrosis of the jaw (n=4, 11%) or healthy individuals (n=6, 13%). We found no differences in the cumulative risk of developing osteonecrosis of the jaw between patients homozygous and heterozygous for the major allele. We were unable to confirm a significant association between this polymorphism and the risk of developing osteonecrosis of the jaw

Risk model for prostate cancer using environmental and genetic factors in the spanish multi-case-control (MCC) study

Prostate cancer (PCa) is the second most common cancer among men worldwide. Its etiology remains largely unknown compared to other common cancers. We have developed a risk stratification model combining environmental factors with family history and genetic susceptibility. 818 PCa cases and 1,006 healthy controls were compared. Subjects were interviewed on major lifestyle factors and family history. Fifty-six PCa susceptibility SNPs were genotyped. Risk models based on logistic regression were developed to combine environmental factors, family history and a genetic risk score. In the whole model, compared with subjects with low risk (reference category, decile 1), those carrying an intermediate risk (decile 5) had a 265% increase in PCa risk (OR = 3.65, 95% CI 2.26 to 5.91). The genetic risk score had an area under the ROC curve (AUROC) of 0.66 (95% CI 0.63 to 0.68). When adding the environmental score and family history to the genetic risk score, the AUROC increased by 0.05, reaching 0.71 (95% CI 0.69 to 0.74). Genetic susceptibility has a stronger risk value of the prediction that modifiable risk factors. While the added value of each SNP is small, the combination of 56 SNPs adds to the predictive ability of the risk model