Sizing of power electronics EMC filters using design by optimization methodology

This paper proposes a synthesis of EMC filter design method for power electronics converters. It starts with the description of the legacy approach, using the usual Common Mode / Differential Mode decomposition, and underlines the need of symmetry and the associated limits. Then an illustration of a design by optimization process is provided in the case of a simple switching cell. Finally, a full system composed of a PFC rectifier is provided, using EMC filters on both AC and DC sides. This example requires a design by optimization, since the two filters exhibit strong interactions

PLEISTOCENE PALAEOCLIMATIC EVOLUTION FROM AGIOS GEORGIOS CAVE SPELEOTHEM (KILKIS, N. GREECE)

Palaeoclimatic reconstruction in N. Greece has been investigated in this study, using stable isotope analyses and U/Th dating of a speleothem (stalactite) from the cave of Agios Georgios (Kilkis). Sampling sequence was followed in detail in order to obtain high resolution analysis of the proxy. Speleothem δ18O entirely depends on two factors: changes in the δ18O of the percolation waters (a proxy for local rainfall δ18O) and the temperature of water-calcite fractionation inside the cave (a proxy for outside air temperatures). During periods of relatively stable temperatures, δ13C shifts are caused principally by variations in soil CO2 input and physico-chemical processes inside the cave. More important processes affect the δ13C signal of speleothem inside the cave are length of flow path and rates of CO2 degassing.The lower δ13C calcite values indicate greater respiratory activity of soils under wetter conditions. The stalagmite layers were dated through U/Th geochronological method, which places the carbonate precipitation in Middle Pleistocene (630-300ka BP). The isotopic composition of the layers was used in combination with the dating results to reconstruct the evolution of the area of Kilkis. Correlation with global climatic records shows that major climatic transitions that influenced northern hemisphere seem to have also affected the region of N. Greece

PLEISTOCENE PALAEOCLIMATIC EVOLUTION FROM AGIOS GEORGIOS CAVE SPELEOTHEM (KILKIS, N. GREECE)

Palaeoclimatic reconstruction in N. Greece has been investigated in this study, using stable isotope analyses and U/Th dating of a speleothem (stalactite) from the cave of Agios Georgios (Kilkis). Sampling sequence was followed in detail in order to obtain high resolution analysis of the proxy. Speleothem δ18O entirely depends on two factors: changes in the δ18O of the percolation waters (a proxy for local rainfall δ18O) and the temperature of water-calcite fractionation inside the cave (a proxy for outside air temperatures). During periods of relatively stable temperatures, δ13C shifts are caused principally by variations in soil CO2 input and physico-chemical processes inside the cave. More important processes affect the δ13C signal of speleothem inside the cave are length of flow path and rates of CO2 degassing.The lower δ13C calcite values indicate greater respiratory activity of soils under wetter conditions. The stalagmite layers were dated through U/Th geochronological method, which places the carbonate precipitation in Middle Pleistocene (630-300ka BP). The isotopic composition of the layers was used in combination with the dating results to reconstruct the evolution of the area of Kilkis. Correlation with global climatic records shows that major climatic transitions that influenced northern hemisphere seem to have also affected the region of N. Greece

Taking into account interactions between converters in the design of aircraft power networks

This paper presents some key interactions among converters, which need to be taken into account when designing a modern embedded electrical grid, including a large amount of Power Electronics based loads. A design by Optimization method is first used to define the converter parameters. During this step, it is mandatory to account for the interaction between the input and output EMI filters. The second step consists in designing the control strategy; the paper will show that the results are largely improved if all converters are considered simultaneously. Finally, the stability study of the embedded network has to be investigated. All these interactions are studied in the example of a three phases AC network, composed of a Voltage Source Inverter and an Active Front End

Sedimentological, mineralogical and geochemical features of late quaternary sediment profiles from the Southern Tuscany Hg Mercury District (Italy): Evidence for the presence of pre-industrial mercury and arsenic concentrations

Southern Tuscany (Italy) is an important metallogenic district that hosts relevant S-polymetallic deposits that have intensely been exploited for centuries. Consequently, potential toxic elements, such as Hg and As, are widely distributed in the surrounding environment. In this paper, an extensive sedimentological, mineralogical and geochemical study of two Late Quaternary sediment profiles, partially outcropping along the coast of southern Tuscany (Ansedonia area), was carried out to evaluate the contents and mobility of Hg and As with the aims to contribute to the definition of the geochemical baseline of southern Tuscany before the human intervention and evaluate the potential dispersion of these harmful elements. The sedimentological, mineralogical and geochemical (major elements) features revealed that the studied profiles are mostly related to the local geological characteristics and the Quaternary geological history of the area. The concentrations and the normalized patterns of trace and rare earth elements highlighted the absence of any anthropogenic activity. This implies that the studied samples are to be regarded as good proxies for evaluating the geochemical baseline of southern Tuscany before the intense mining activity. The enrichment factors (EF) of most trace elements were indeed lower or close to 2, indicating a variability close to the average concentration of the Upper Continental Crust (UCC), while other elements slightly enriched, such as Pb, were in agreement with the natural baseline reported for southern Tuscany. Mercury and As displayed EF values >40 when compared to the average contents of UCC, although they decrease down to 4 when compared to the suggested baseline for southern Tuscany. The higher Hg and As contents detected in this study, inferred to natural sources, evidenced (i) the great natural variability occurring in largely mineralized areas and (ii) the importance of estimating reference environmental parameters in order to avoid misleading interpretations of the detected anomalies. Moreover, the results of leaching test on sediment samples denoted a relatively low mobility of Hg and As, suggesting that these elements are preferentially mobilized by transport of clastic sediments and such anomalies may be preserved for relatively long times in Quaternary sediments. However, leachable Hg (0.6-9.7 μg/L) and As (2.1-42.2 μg/L) concentrations are significantly high when compared to those of the Italian limit for groundwater (1 μg/L for Hg and 10 μg/L for As). Quaternary sediments from southern Tuscany could then be a potential, though natural, source of Hg and As to groundwater systems

DiagText: manual do usuário.

DiagText é uma ferramenta que teve como objetivo inicial auxiliar o processo de extração de informações de documentos textuais que descrevem doenças de culturas agrícolas para formação de uma árvore de decisão baseada nos sintomas das doenças avaliadas.bitstream/item/11847/1/doc84.pd

Platypnea-orthodeoxia due to osteoporosis and severe kyphosis: a rare cause for dyspnea and hypoxemia

Platypnea orthodeoxia is a rare disorder characterized by dyspnea and arterial desaturation, exacerbated by the upright position and relieved when the subject is recumbent. We report the case of a 79-year old woman admitted to hospital with dyspnea who was thought to have restrictive ventilatory impairment due to osteoporosis and severe kyphosis. Interestingly, the dyspnea was aggravated in the upright position, whereas the symptoms improved in the supine position. Arterial blood gas analysis confirmed orthodeoxia. The lung function test showed only a mild obstructive and restrictive ventilation disorder. Echocardiography revealed a patent foramen ovale and an aneurysm of the atrial septum protruding into the left atrium, despite normal right atrial pressure. Transesophageal echocardiography showed a prominent Eustachian valve guiding a blood flow from the inferior vena cava directly onto the atrial septum, thereby pushing open the patent foramen ovale. Contrast-enhanced echocardiography confirmed a spontaneous right-to-left shunt through the patent foramen ovale. It was assumed that the platypnea-orthodeoxia was caused by a prominent Eustachian valve redirected to the patent foramen ovale as a result of severe osteoporosis with subsequent thoracic kyphosis and a change in the position of the entire heart. The patient underwent permanent transcatheter closure of the patent foramen ovale after hemodynamic assessment had confirmed a significant right-to-left shunt through it. After the procedure the arterial oxygen pressure increased significantly in the upright position and dyspnea improved

GIS-assisted modelling for debris flow hazard assessment based on the events of May 1998 in the area of Sarno, Southern Italy. Part I: Maximum run-out

Based on the debris flow events that occurred in May 1998 in the area of Sarno, Southern Italy, this paper presents an approach to simulate debris flow maximum run-out. On the basis of the flow source areas and an average thickness of 1.2 m of the scarps, we estimated debris flow volumes of the order of 104 and 105 m3. Flow mobility ratios ( H/L) derived from the x,y,z coordinates of the lower-most limit of the source areas (i.e. apex of the alluvial fan) and the distal limit of the flows ranged between 0.27 and 0.09. We performed regression analyses that showed a good correlation between the estimated flow volumes and mobility ratios. This paper presents a methodology for predicting maximum run-out of future debris flow events, based on the developed empirical relationship. We implemented the equation that resulted from the calibration as a set of GIS-macros written in Visual Basic for Applications (VBA) and running within ArcGIS. We carried out sensitivity analyses and observed that hazard mapping with this methodology should attempt to delineate hazard zones with a minimum horizontal resolution of 0.4 km. The developed procedure enables the rapid delineation of debris flow maximum extent within reasonable levels of uncertainty, it incorporates sensitivities and it facilitates hazard assessments via graphic-user interfaces and with modest computing resources