No abstract

Functionally graded materials (FGM) have spatial distribution of a material property in order to achieve efficient stress control. An application of the FGM to a solid insulator (spacer) for a gaseous insulation system, like gas insulated switchgear, is expected to improve electric field (Efield) distribution around the spacer.In this paper, we describe the applicability of the FGM spacer to gas insulated power equipment. In the FGM spacer, we gave spatial distribution of dielectric permittivity to control the E-field distribution inside and outside the spacer. This paper includes following key results for the applications of the FGM. Firstly, E-field simulation results when applying the FGM by a finite element method are presented, in which we show the effective reduction of the maximum field strength by applying the FGM. Next, a fabrication technique of the FGM spacer sample with not only step-by-step but also continuous changes of permittivity is presented by use of centrifugal force. Finally, dielectric breakdown tests using FGM samples which are accurately controlled the spatial distribution of permittivity are carried out under lightning impulse voltage applications. The test result indicates the increase of breakdown voltage (BDV). From these results, we verified the applicability and the fabrication technique of FGM spacer for improvement of the dielectric strength in the gaseous insulation system.

PurposeElbow fractures are common in children and occur during daily activities. The aim of this study is to evaluate the epidemiology of paediatric elbow fractures over a two-year period in Okinawa, a southern subtropical island in Japan.MethodsThis was a retrospective study of 488 elbow fractures in children younger than 15 years old treated at 11 hospitals in Okinawa. Data included age, gender, calendar month, type of fracture, operation rate, mechanism of injury, and aetiology.ResultsThe most frequent age was 6 years old, with 47.5% of all elbow fractures occurring in an age range from 6 to 10 years old. The fracture rate for boys was 1.6 times higher than that for girls. The incidence was the highest in May (56 fractures) and the lowest in August (25 fractures). Supracondylar fractures were the most common type (44%), followed by lateral condyle fractures (22%); 45% of all fractures were treated operatively. Medial epicondyle fractures had the highest rate of operative treatment (91%). In the 6 to 10-year-old group, 19% of all fractures occurred while skateboarding or caster-boarding, the most frequent aetiology.ConclusionsSupracondylar fractures are the most common fracture type in 4 to 7-year-old boys. In the 6 to 10-year-old group, skateboarding and caster-boarding are the most frequent and increasing cause of elbow fractures. Therefore, some preventive measures are needed.Level of evidenceLevel IV, case series

No abstract

No abstract