The synthesis of Dipyrido [1,2-a:2’ ,1-c] Pyrazidiinium salts

Not availabl

PD activity in void type dielectric samples for varied DC polarity

This paper discusses the DC testing of a dielectric sample (with voids) under DC conditions. The ramp test method was employed to assess whether the tests were repeatable. Three DC ramp tests were performed in quick succession. The polarity of the first/third tests was positive and the polarity of the second test was negative. The resultant partial discharge activity was analyzed for each series of tests and compared for positive and negative conditions. The results show that the inclusion of a negative ramp between two positive ramps enabled similar PD activity to be recorded in the first and second positive ramp tests. The negative cycle was used to re-initialise the test sample and allows trapped charge to migrate enabling similar PD activity in the subsequent positive ramp test. Changes in PD behavior were observed in the distribution of PD data between the tests

Long term testing and analysis of dielectric samples under DC excitation

This paper details testing conducted under DC conditions on a dielectric sample containing internal voids. The DC testing was conducted using a ramp method to vary the voltage applied to the dielectric sample. The dielectric sample was de-energised for a week prior to two separate identical ramp tests and the results are presented showing the variability of PD activity. After the second ramp test an additional ramp test was performed in quick succession and PD activity was reduced, emphasizing the importance of de-energising the sample between tests. A major challenge associated with void type dielectric samples is ensuring that repeatable results are generated and possible approaches are discussed

Laboratory and field partial discharge measurement in HVDC power cables

A range of experimental and field measurements of partial discharge (PD) activity under high voltage direct current (HVDC) conditions have been conducted with the goal of developing effective monitoring techniques for PD in HVDC cables and ancillary equipment, particularly in offshore renewable energy HVDC grid installations. Laboratory measurements on insulation test objects and cross linked polyethylene (XLPE) cable samples have been conducted to better understand the characteristics of PD activity under direct current (DC) stress in comparison with AC. In addition, long-term PD measurements carried out at both an HVDC cable aging laboratory and an in-service HVDC interconnector circuit are presented together with a description of the monitoring system architecture

Perfectionism and personality

This chapter provides a synopsis of research on where multidimensional perfectionism “fits” within the broader framework of contemporary personality theory. Focusing on Hewitt and Flett’s (1991) model of perfectionism--differentiating self-oriented, other-oriented, and socially prescribed perfectionism--the chapter presents a summary and critical discussion of how multidimensional perfectionism relates to the dimensions and facets of two major structural models of personality (the five-factor model and the HEXACO model) and one neuropsychological model of personality (reinforcement sensitivity theory). Implications of the findings for multidimensional theories and models of perfectionism, as well as future perfectionism research, are discussed

(Multi)letramento(s) e identidade : an?lise de cartazes produzidos no ?mbito do grupo de hip-hop ?a rede? em Ouro Preto ? MG.

Este artigo tem por objetivo apresentar uma an?lise lingu?stico-discursiva de cartazes multimodais produzidos no ?mbito do grupo de hip-hop ?A rede?, de Ouro Preto ? MG. Apoiamo-nos nos estudos sobre os letramentos (os chamados Novos Letramentos e os multiletramentos), principalmente no ?mbito dos estudos lingu?sticos e da educa??o. A an?lise partiu de uma coleta de dados realizada por meio da observa??o participante e entrevistas, de abordagem etnogr?fica. Os resultados demonstram que os participantes do grupo ?A rede? produzem textos multimodais eficientes em seus objetivos e que demarcam seus lugares sociais com a ressignifica??o de suas identidades. Essas pr?ticas sociais multiletradas espont?neas e engajadas n?o s?o, muitas vezes, reconhecidas e valorizadas pela escola

Contrasts in hydrology between regions of basal deformation and sliding beneath Rutford Ice Stream, West Antarctica, mapped using radar and seismic data

[1] Spatially coincident radar and seismic data collected two weeks apart on Rutford Ice Stream were analyzed to investigate the mechanical and hydrological characteristics of the ice-bed interface. Seismic data allow the differentiation of bed deformation from basal sliding. In radar data, sliding regions are characterised by highly variable permittivity values. We suggest these regions are characterized by small water bodies, possibly a cavity system. In contrast, deforming regions are characterised by consistent, low permittivity, which suggests intimate ice-sediment contact without a distinct interface. However, in deforming regions we identified three bright radar features similar to 50 m wide, consistent in lateral location over distances of 5-10 km up and downstream, and comprised of water less than similar to 0.2 m deep. We interpret these as part of a water evacuation system, most likely canals. Our results emphasise the great potential of radar and seismic techniques in combination to infer basal conditions beneath ice streams

Morphology-directed synthesis of LiFePO4 and LiCoPO4 from nanostructured Li1+2xPO3+x

A LiPO3-type nanostructure has been developed using a simple microwave approach at temperatures as low as 200 °C. This phase presents an ideal architecture for the morphology-directed synthesis of the olivine-type phases LiFePO4 and LiCoPO4, through a simple and scalable solution-based technique. Pure and carbon-composited olivine phases of interconnected nanoparticulate morphologies display excellent performance at high rates (up to 20 C) over 500 cycles in Li-ion battery cells

Selective and facile synthesis of sodium sulfide and sodium disulfide polymorphs

Na2S and Na2S2 were selectively synthesized using a microwave-assisted thermal treatment of a Na+/S solution in tetraglyme between 100 and 200 °C, considerably lower than that of current routes. This novel synthetic pathway yields the Na2S phase in high purity and allows for good selectivity between the polymorphs of Na2S2 (α and β phases). These materials show promising electrochemical properties and are particularly interesting for the continued development of Na–S batteries