1,737 research outputs found
Integral Formulation for Losses Computation in Tripolar Submarine Cables with Shield Wires, Moisture Barriers and Armor
No full textMethod-of-Moments (MoM) is coupled with PEEC in order to compute Joule and hystheresis losses in the armor, shields and moisture barriers of a submarine tripolar cable. The large size and complex structure of the linear algebraic system resulting from the problem discretization demands for a suitably tailored solver. We describe a block-Gauß-Seidel preconditioner for Krylov subspace methods that allows for a matrix-free solver implementation, resulting in a dramatic reduction of computation time and memory requirements w.r.t. other brute-force modeling approaches
MoM Computation of Losses of an Array of Parallel Magnetic and Conductive Wires in a Transverse Magneto-quasi-static Field
No full textA Trefftz-like method is proposed for the evaluation of losses in an array of parallel magnetic and conductive wires subject to an external time-harmonic magneto-quasi-static field. The formulation is tested on a two-dimensional model of a submarine three-core power cable armor. The accuracy of the method is verified by comparison with a reference Finite Element Method solutio
An Integral Formulation for an Array of Wires in a 3-D Magneto-Quasi-Static Field
No full textThere are many applications in which it is required to compute quasi-stationary magnetic fields and related quantities in possibly large regions containing many magnetic and/or conductive thin wires. When analyzing these problems by the finite-element method, one has to discretize the wires into fine elements in order to resolve the skin effect and the space separating the wires. Heavy computational burden is, therefore, needed to solve the resulting equations. To overcome such limitations, we propose a magnetic field integral formulation in the magneto-quasi-static regime that is suitable for computing the magnetic field in a 3-D domain in the presence of thin wires. To reduce the computational complexity, the wires are treated as 1-D manifolds embedded in the surrounding 3-D space. To validate the proposed methodology, we compare the cost and accuracy of our approach to full scale finite-element simulations of an array of wires in a 3-D external magneto-quasi-static field
Computation of Armor Losses in AC Submarine Cables
Get PDFWe propose an innovative fast 3D approach for the accurate computation of electromagnetic losses in the metallic armors of submarine cables. In order to develop a scheme that is more efficient with respect to most commonly used 3D simulation methods, typically based on the Finite Element Method (FEM), we proceed by proposing a suitable discretization of an integral formulation. In the proposed approach, each wire of the armor is modeled as filamentary which leads to a dramatic reduction in the number of degrees of freedom in the numerical model and in the overall computational burden. The new approach can be applied to cables where armor wires are stranded either with opposite (contralay) or same (equilay) orientation as the central phase cables. The efficiency of the proposed method is especially notable in latter case for which FEM is very demanding due to the extremely large model size. The reduction in both computation times and memory footprint allow performing extensive sensitivity studies with respect to geometrical parameters and material properties that would be otherwise unaffordable with existing 3D methods
Fully Coupled Computation of Losses in Metallic Sheaths and Armor of AC Submarine Cables
No full textThe problem of computing in an efficient and accurate way the armor losses in three-core AC submarine cables has been of great interest to the offshore cable community for some years. Indeed, efficiency of the computation method is crucial to allow comprehensive parametric analysis as might be needed in the design study. In [1] an algorithm based on integral equations for performing such calculations with an accuracy comparable (within acceptable tolerances) to state-ofthe- art Finite Element Method (FEM) approaches was presented. In the present study, we extend the above mentioned algorithm to account for the mutual inductive coupling between armor wires and metallic screens, which are often present in actual cables structure. We show that the most notable properties of the original algorithm are preserved in this coupled formulation. In particular we discuss how exploiting the cable structure periodicity and symmetry leads to huge computational cost reductions. The new extended simulation tool is applied to a parametric study to assess how geometry and material properties influence losses and to assess in particular the impact of the metallic sheaths
An Integral Formulation for Rectangular Wires in a 3D Magneto-Quasi-Static Field
Get PDFThis paper proposes an integral formulation for calculating the magnetic and ohmic losses
in rectangular wires immersed in an external 3D magneto-quasi-static field. The formulation is based on
some simplifying assumptions that allow to employ a collocation method with constant elements for the
discretization, reducing the computational burden. Even if the assumptions introduce an approximation,
for the application at hand the numerical tests have shown that the accuracy is still acceptable. Moreover,
the computational time is drastically reduced with respect to other approaches based on the finite element
method
Recuerdos de Massimo.
Get PDFEl presente ensayo recuerda la rica relación personal e intelectual entre Massimo Pavarini e Iñaki Rivera Beiras desde que el segundo conoció siendo muy joven a Pavarini. En ese sentido, el trabajo recuerda los inicios de su fecunda relación en la ciudad de Bologna cuando Iñaki Rivera acudía a presentar a Massimo Pavarini los desarrollos de lo que sería su tesis doctoral. Las contribuciones de Pavarini al proceso de aprendizaje de Rivera, en el terreno de una epistemología crítica en la penología contemporánea, son analizados como un homenaje a la memoria y a la obra del autor italiano, tras su fallecimiento en septiembre de 2015.This paper recalls the rich personal and intellectual relationship between Massimo Pavarini and Iñaki Rivera Beiras. In that sense , the work recalls the beginning of his fruitful relationship in the city of Bologna when Iñaki Rivera came to present Massimo Pavarini’ developments in what would be his PhD thesis. Pavarini contributions to the learning process of Rivera, on the ground of a critical epistemology in contemporary penology , are analyzed as a tribute to the memory and to the work of Italian author, after his death in September 2015 .El presente ensayo recuerda la rica relación personal e intelectual entre Massimo Pavarini e Iñaki Rivera Beiras desde que el segundo conoció siendo muy joven a Pavarini. En ese sentido, el trabajo recuerda los inicios de su fecunda relación en la ciudad de Bologna cuando Iñaki Rivera acudía a presentar a Massimo Pavarini los desarrollos de lo que sería su tesis doctoral. Las contribuciones de Pavarini al proceso de aprendizaje de Rivera, en el terreno de una epistemología crítica en la penología contemporánea, son analizados como un homenaje a la memoria y a la obra del autor italiano, tras su fallecimiento en septiembre de 2015
Predoni a casa nostra e il geografo solidale: Massimo Quaini tra terra e acqua
Get PDFIn accordance with the main goals of this collection of essays in honour of Massimo Quaini, the text focuses on a peculiar character of the Ligurian geographer’s sensibility, his attention to landscape protectionresearch activity developed in the context of the humanistic geography. Starting from a personal narrative based on his own reminiscences and neglected memories, the author tries to shed light on the relationships between civil commitment and cultural reflection which characterize environmental sensitivity, bringing together his interests with Quaini’s emotional geographies. Finally, some of Quaini’s everyday practicalities are highlighted as the easiest doorway to improve the cognitive procedures of cultural geography
Is Felix Salten the author of the Mutzenbacher novel (1906)? Yes and no
No full textJosefine Mutzenbacher oder die Geschichte einer Wienerischen Dirne von ihr selbst erzählt, published in Vienna in 1906, represents one of the most fascinating cases of attribution of authorship in German literature. Although Josefine Mutzenbacher is usually attributed to Felix Salten, the author of the world-famous Bambi (1923), the novel’s authorship has never been confirmed, and many other candidates have been named as potential authors. Among them is Arthur Schnitzler, who published Reigen, a cycle of amorous adventures in Viennese society, in 1903. Some scholars, instead, have attributed the novel to such lesser-known writers as Ernst Klein and Willi Handl. The controversy surrounding the authorship of Josefine Mutzenbacher was the starting point for our stylometric analyses, and our results help to answer some unresolved questions in a debate that has lasted for more than 100 years. The analyses were performed using the R package Stylo, which enables an efficient application of Burrows’ Delta and its variants. Focusing on both the entire text and on the final pages, two different types of analysis were carried out: one combines 1200 different stylometric methods to compare the candidate authors Salten, Schnitzler, Bahr, Altenberg, Hofmannsthal, Klein and Handl; the other verifies the attribution using the ‘impostors’ method. The results show that the most probable author is Felix Salten, while none of the candidates could be identified as the author of the final pages, confirming the hypothesis that the text was left unfinished by Salten and completed by an as-yet-unidentified ghost-writer
Plastid Genotyping Reveals the Uniformity of Cytoplasmic Male Sterile-T Maize Cytoplasms
No full textCytoplasmic male-sterile (CMS) lines in maize (Zea mays) have been classified by their response to specific restorer genes into three categories: cms-C, cms-S, and cms-T. A mitochondrial genome representing each of the CMS cytotypes has been sequenced, and male sterility in the cms-S and cms-T cytotypes is linked to chimeric mitochondrial genes. To identify markers for plastid genotyping, we sequenced the plastid genomes of three fertile maize lines (B37, B73, and A188) and the B37 cms-C, cms-S, and cms-T cytoplasmic substitution lines. We found that the plastid genomes of B37 and B73 lines are identical. Furthermore, the fertile and CMS plastid genomes are conserved, differing only by zero to three single-nucleotide polymorphisms (SNPs) in coding regions and by eight to 22 SNPs and 10 to 21 short insertions/deletions in noncoding regions. To gain insight into the origin and transmission of the cms-T trait, we identified three SNPs unique to the cms-T plastids and tested the three diagnostic SNPs in 27 cms-T lines, representing the HA, I, Q, RS, and T male-sterile cytoplasms. We report that each of the tested 27 cms-T group accessions have the same three diagnostic plastid SNPs, indicating a single origin and maternal cotransmission of the cms-T mitochondria and plastids to the seed progeny. Our data exclude exceptional pollen transmission of organelles or multiple horizontal gene transfer events as the source of the mitochondrial urf13-T (unidentified reading frame encoding 13-kD cms-T protein) gene in the cms-T cytoplasms. Plastid genotyping enables a reassessment of the evolutionary relationships of cytoplasms in cultivated maize.Peer reviewe
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