Properties of Sequential Chromospheric Brightenings and Associated Flare Ribbons

We report on the physical properties of solar sequential chromospheric brightenings (SCBs) observed in conjunction with moderate-sized chromospheric flares with associated CMEs. To characterize these ephemeral events, we developed automated procedures to identify and track subsections (kernels) of solar flares and associated SCBs using high resolution H-alpha images. Following the algorithmic identification and a statistical analysis, we compare and find the following: SCBs are distinctly different from flare kernels in their temporal characteristics of intensity, Doppler structure, duration, and location properties. We demonstrate that flare ribbons are themselves made up of subsections exhibiting differing characteristics. Flare kernels are measured to have a mean propagation speed of 0.2 km/s and a maximum speed of 2.3 km/s over a mean distance of 5 x 10^3 km. Within the studied population of SCBs, different classes of characteristics are observed with coincident negative, positive, or both negative and positive Doppler shifts of a few km/s. The appearance of SCBs precede peak flare intensity by ~12 minutes and decay ~1 hour later. They are also found to propagate laterally away from flare center in clusters at 41 km/s or 89 km/s. Given SCBs distinctive nature compared to flares, we suggest a different physical mechanism relating to their origin than the associated flare. We present a heuristic model of the origin of SCBs.Comment: 24 pages, 17 figure

High frequency Alternating Current (AC) tangent delta

Power cables are constantly subjected to thermal, electrical and mechanical stresses during their service life which leads to ageing of the insulation material. Ageing of the insulation means that the insulator degrades or gets older. When the insulation is degraded it does not have the same physical properties as compared to the new cables, which basically means that the risk of failure has been increased. So, it is necessary to carry out a diagnostic test to resolve the possible problem that may occur in cable insulation so that precautionary action can be taken to avoid unnecessary in-service failure of the underground cable [1]. Dissipation factor or tangent delta measurement in either time or frequency domain are used to identify water tree degraded XLPE cables with high moisture content or moisture ingression through poor jointing, diagnostic tests based on [2], [3]. In practice, standard laboratory electrical test equipment utilizing power frequency (PF) i.e. 50Hz to 60Hz testing is used. Hence, large static transformer was installed in the laboratory to cater any large capacitance test sample for high voltage testing. These existing tangent delta diagnostic test methods are bulk assessment technique that cannot sectionalize or pin point the water tree or any other conductive defect. In addition, both this tangent delta measurement technique which utilizes standard 0.1Hz and 50Hz equipment is not capable to extract the tangent delta values of accessories from the bulk assessment. It can only diagnose the overall condition of the complete cable system that includes cable, joints and terminations. Since medium voltage underground (MVUG) cables in utilities are in service for many years, it is crucial to develop a method to sectionalize or identify the defective components

The Origin of Sequential Chromospheric Brightenings

Sequential chromospheric brightenings (SCBs) are often observed in the immediate vicinity of erupting flares and are associated with coronal mass ejections. Since their initial discovery in 2005, there have been several subsequent investigations of SCBs. These studies have used differing detection and analysis techniques, making it difficult to compare results between studies. This work employs the automated detection algorithm of Kirk et al. (Solar Phys. 283, 97, 2013) to extract the physical characteristics of SCBs in 11 flares of varying size and intensity. We demonstrate that the magnetic substructure within the SCB appears to have a significantly smaller area than the corresponding H-alpha emission. We conclude that SCBs originate in the lower corona around 0.1 R_sun above the photosphere, propagate away from the flare center at speeds of 35 - 85 km/s, and have peak photosphere magnetic intensities of 148 +/- 2.9 G. In light of these measurements, we infer SCBs to be distinctive chromospheric signatures of erupting coronal mass ejections.Comment: 25 pages, 9 figures, 5 table

Random telegraph signal amplitudes in sub 100 nm (decanano) MOSFETs: a 3D `Atomistic' simulation study

In this paper we use 3D simulations to study the amplitudes of random telegraph signals (RTS) associated with the trapping of a single carrier in interface states in the channel of sub 100 nm (decanano) MOSFETs. Both simulations using continuous doping charge and random discrete dopants in the active region of the MOSFETs are presented. We have studied the dependence of the RTS amplitudes on the position of the trapped charge in the channel and on the device design parameters. We have observed a significant increase in the maximum RTS amplitude when discrete random dopants are employed in the simulations

Discriminant analysis of selected variables in the adoption of fish curing

Discriminant functions were worked out for adoption or non-adoption of five improved practices in fish curing. Four variables measured quantitatively formed the basis for discrimination. In four out of five equations, the selected variables were found to discriminate significantly between the adopters and non-adopters

The relationship between stress and job performance among IT professionals in Jaffna district.

The modern-day businesses heavily depend on Information Technologies and systems. It leads to expanded job roles, increased the work demands and over pressures of Information Technology professionals. This study intended to find out the relationship between stress and job performance among IT professionals in Jaffna district. Snowball sampling technique was used and data were collected from 88 respondents by using E-Questionnaires through electronic media. Correlation analysis was done to carry out the study. The findings of the study revealed that stress is negatively co related (r= - 0.6917) with job performance of IT Professionals. The paper concludes with recommendations for further research