25,735 research outputs found

    Space charge and charge trapping characteristics of cross-linked polyethylene subjected to ac electric stresses

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    This paper reports on the result of space charge evolution in cross-linked polyethylene (XLPE) planar samples of approximately 220 ?m thick. The space charge measurement technique used in this study is the PEA method. There are two phases to this experiment. In the first phase, the samples were subjected to dc 30 kVdc/mm and ac (sinusoidal) electric stress level of 30 kVpk/mm at frequencies of 1 Hz, 10 Hz and 50 Hz ac. In addition, ac space charge under 30 kVrms/mm and 60 kVpk/mm electric stress at 50 Hz was also investigated. The volts off results showed that the amount of charge trapped in XLPE sample under dc electric stress is significantly bigger than samples under ac stress even when the applied ac stresses are substantially higher. The second phase of the experiment involves studying the dc space charge evolution in samples that were tested under ac stress during the first phase of the experiment. Ac ageing causes positive charge to become more dominant over negative charge. It was also discovered that ac ageing creates deeper traps, particularly for negative charge. This paper also gave a brief overview of the data processing methods used to analyse space charge under ac electric stress

    Symmetry-dependent vibrational excitation in K-shell photoionization of CO and N-2: Experiment and theory

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    Ueda, K (Ueda, K.); Matsumoto, M (Matsumoto, M.); Hatamoto, T (Hatamoto, T.); Liu, XJ (Liu, X.-J.); Lischke, T (Lischke, T.); Prumper, G (Pruemper, G.); Tanaka, T (Tanaka, T.); Hoshino, M (Hoshino, M.); Makochekanwa, C (Makochekanwa, C.); Kitajima, M (Kitajima, M.); Tanaka, H (Tanaka, H.); Harries, JR (Harries, J. R.); Tamenori, Y (Tamenori, Y.); Ehara, M (Ehara, M.); Kuramoto, K (Kuramoto, K.); Nakatsuj, H (Nakatsuj, H.

    Tanaka spaces and products of sequential spaces

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    summary:We consider properties of Tanaka spaces (introduced in Mynard F., {\it More on strongly sequential spaces\/}, Comment. Math. Univ. Carolin. {\bf 43} (2002), 525--530), strongly sequential spaces, and weakly sequential spaces. Applications include product theorems for these types of spaces

    Molecular taxonomy of bambusicolous fungi: Tetraplosphaeriaceae, a new pleosporalean family with Tetraploa-like anamorphs

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    AbstractA new pleosporalean family Tetraplosphaeriaceae is established to accommodate five new genera; 1) Tetraplosphaeria with small ascomata and anamorphs belonging to Tetraploa s. str., 2) Triplosphaeria characterised by hemispherical ascomata with rim-like side walls and anamorphs similar to Tetraploa but with three conidial setose appendages, 3) Polyplosphaeria with large ascomata surrounded by brown hyphae and anamorphs producing globose conidia with several setose appendages, 4) Pseudotetraploa, an anamorphic genus, having obpyriform conidia with pseudosepta and four to eight setose appendages, and 5) Quadricrura, an anamorphic genus, having globose conidia with one or two long setose appendages at the apex and four to five short setose appendages at the base. Fifteen new taxa in these genera mostly collected from bamboo are described and illustrated. They are linked by their Tetraploa s. l. anamorphs. To infer phylogenetic placement in the Pleosporales, analyses based on a combined dataset of small- and large-subunit nuclear ribosomal DNA (SSU+LSU nrDNA) was carried out. Tetraplosphaeriaceae, however, is basal to the main pleosporalean clade and therefore its relationship with other existing families was not completely resolved. To evaluate the validity of each taxon and to clarify the phylogenetic relationships within this family, further analyses using sequences from ITS-5.8S nrDNA (ITS), transcription elongation factor 1-α (TEF), and β-tubulin (BT), were also conducted. Monophyly of the family and that of each genus were strongly supported by analyses based on a combined dataset of the three regions (ITS+TEF+BT). Our results also suggest that Tetraplosphaeria (anamorph: Tetraploa s. str.) is an ancestral lineage within this family. Taxonomic placement of the bambusicolous fungi in Astrosphaeriella, Kalmusia, Katumotoa, Massarina, Ophiosphaerella, Phaeosphaeria, Roussoella, Roussoellopsis, and Versicolorisporium, are also discussed based on the SSU+LSU phylogeny.Taxonomic novelties: Tetraplosphaeriaceae Kaz. Tanaka & K. Hiray., fam. nov., Tetraplosphaeria Kaz. Tanaka & K. Hiray., gen. nov., Tetraplosphaeria nagasakiensis Kaz. Tanaka & K. Hiray., sp. nov., Tetraplosphaeria sasicola Kaz. Tanaka & K. Hiray., sp. nov., Tetraplosphaeria tetraploa (Scheuer) Kaz. Tanaka& K. Hiray., comb. nov., Tetraplosphaeria yakushimensis Kaz. Tanaka, K. Hiray. & Hosoya, sp. nov., Triplosphaeria Kaz. Tanaka& K. Hiray., gen. nov., Triplosphaeria acuta Kaz. Tanaka & K. Hiray., sp. nov., Triplosphaeria cylindrica Kaz. Tanaka & K. Hiray., nom. nov., Triplosphaeria maxima Kaz. Tanaka & K. Hiray., sp. nov., Triplosphaeria yezoensis (I. Hino & Katum.) Kaz. Tanaka, K. Hiray. & Shirouzu, comb. nov., Polyplosphaeria Kaz. Tanaka & K. Hiray., gen. nov., Polyplosphaeria fusca Kaz. Tanaka& K. Hiray., sp. nov., Pseudotetraploa Kaz. Tanaka & K. Hiray., gen. nov., Pseudotetraploa curviappendiculata (Sat. Hatak., Kaz. Tanaka & Y. Harada) Kaz. Tanaka & K. Hiray., comb. nov., Pseudotetraploa javanica (Rifai, Zainuddin & Cholil) Kaz. Tanaka& K. Hiray., comb. nov., Pseudotetraploa longissima (Sat. Hatak., Kaz. Tanaka & Y. Harada) Kaz. Tanaka & K. Hiray., comb. nov., Quadricrura Kaz. Tanaka, K. Hiray. & Sat. Hatak., gen. nov., Quadricrura bicornis Kaz. Tanaka, K. Hiray. & H. Yonez., sp. nov., Quadricrura meridionalis Kaz. Tanaka & K. Hiray., sp. nov., Quadricrura septentrionalis Kaz. Tanaka, K. Hiray. & Sat. Hatak., sp. nov

    A possible four-phase coexistence in a single-component system

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    For different phases to coexist in equilibrium at constant temperature T and pressure P, the condition of equal chemical potential μ must be satisfied. This condition dictates that, for a single-component system, the maximum number of phases that can coexist is three. Historically this is known as the Gibbs phase rule, and is one of the oldest and venerable rules of thermodynamics. Here we make use of the fact that, by varying model parameters, the Gibbs phase rule can be generalized so that four phases can coexist even in single-component systems. To systematically search for the quadruple point, we use a monoatomic system interacting with a Stillinger-Weber potential with variable tetrahedrality. Our study indicates that the quadruple point provides flexibility in controlling multiple equilibrium phases and may be realized in systems with tunable interactions, which are nowadays feasible in several soft matter systems such as patchy colloids
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