Investigating The Effect of Switching and tripping on Flashover and Breakdown in Circuit Breaker

The need for electrical power is increasing rapidly. The power is transmitted over long distance that made it establish to use high voltage .this need to created circuit breaker. Are an essential part of power system and it plays a major role in study and control. Circuit breaker use SF6 gas circuit breaker as insulation medium. The paper interested in study the SF6 gas circuit breaker; characteristics and advantages and how to deal with it, The paper interested in investigating the effect of switching, tripping on flashover and breakdown on SF6 gas circuit breaker. It shows the main factors which that effected in the SF6 gas circuit breaker performance and which caused faults flashover and tripping. The factors that caused faults may be from the circuit breaker itself or may be related with any part from circuit breaker such as transmission line location. Keywords: SF6 gas circuit breaker, circuit breaker, transmission line, location and moisture

Off-line handwritten signature recognition by wavelet entropy and neural network

Handwritten signatures are widely utilized as a form of personal recognition. However, they have the unfortunate shortcoming of being easily abused by those who would fake the identification or intent of an individual which might be very harmful. Therefore, the need for an automatic signature recognition system is crucial. In this paper, a signature recognition approach based on a probabilistic neural network (PNN) and wavelet transform average framing entropy (AFE) is proposed. The system was tested with a wavelet packet (WP) entropy denoted as a WP entropy neural network system (WPENN) and with a discrete wavelet transform (DWT) entropy denoted as a DWT entropy neural network system (DWENN). Our investigation was conducted over several wavelet families and different entropy types. Identification tasks, as well as verification tasks, were investigated for a comprehensive signature system study. Several other methods used in the literature were considered for comparison. Two databases were used for algorithm testing. The best recognition rate result was achieved by WPENN whereby the threshold entropy reached 92%

Space charge behaviour in epoxy laminates under high constant electric field

The development of space charge in insulating materials is one of the main causes of their electrical ageing. The pulsed electro-acoustic method is often used to determine space charge distribution, but the signal analysis in the case of laminate structures is much more complex to analyse. In this paper the authors describe and use a simulated signal in order to study laminates made of epoxy resin and fibre mat. The relatively large conductivity of the fibres compared with that of the resin seems to produce a rapid charge dissociation and recombination in the fibres. Under voltage the presence of fibres close to an electrode seems to promote charge injection

Room-Temperature Hysteresis in a Hole-Based Quantum Dot Memory Structure

We demonstrate a memory effect in self-assembled InAs/Al0.9Ga0.1As quantum dots (QDs) near room temperature. The QD layer is embedded into a modulation-doped field-effect transistor (MODFET) which allows to charge and discharge the QDs and read out the logic state of the QDs. The hole storage times in the QDs decrease from seconds at 200 K down to milliseconds at room temperature

Darcy flow and heat transfer of nanoliquid within a porous annulus with incorporating magnetic terms

Current investigation was carried out to analyze the treatment of nanomaterial within a domain which experienced magnetic force. Outer rhombus wall is cold and the inner circle has uniform heat flux and due to these conditions, carrier fluid rotates counterclockwise. Darcy law was used for simulation and Joule heating was neglected in equations. Influences of parameters were discussed in plots and contours and CVFEM has been employed to reach such outputs. Rotational core becomes stronger with the rise of Ra while opposite results have been accomplished with the soar of Ha. In cases with higher values of shape factor, Nu has higher values and a similar trend is reported for Rd. Moreover, Nu experiences 30% reduction when Ha augments. This negative impact becomes more sensible when radiation terms are added in equations. Inclusion of nano powders has a favorable impact on Nu although it has a negative impact on temperature gradient

Thermal assessment of cold storage process involving nanomaterial via numerical approach

The primary aim of this study is to extend a numerical approach aimed at improving the efficiency of the solidification process. Two key strategies, namely the scattering of nano-powders and the installation of fins, were employed to intensify freezing. By approximating and neglecting the influence of velocity terms, the final equations were streamlined to form a mathematical model. To enhance accuracy, mesh adaptation was integrated with the Galerkin method for solving the model. Various scenarios were examined to assess the impression of both the shape and concentration of nano-powders on freezing. A significant correlation was observed between the concentration of additives and the efficiency of conduction, causing in a decrement in the required solidification time by approximately 32.8 %. Furthermore, modifying the shape of the nano-powders and selecting those with a higher shape factor substantially improved freezing efficiency, resulting in an increase of approximately 10.89 %

Increment of solidification rate due to radiation and conduction mechanism in existence of porous container filled with nanomaterial

In current study, Galerkin techniques have been utilized to model the freezing behavior of a cold storage unit. The system features fins and porous foam, enhancing its efficiency in solidifying liquids. Additionally, hybrid nanoparticles have been introduced into the water to improve its conductivity. The energy equation has been augmented with a new term for radiation mode, alongside the source term for freezing. With the goal of determining the amounts of scalars at each node, the model consists of two equations. Mesh adaptation techniques have been employed to accommodate the dynamic nature of the process. Validation against previous data demonstrates good agreement, bolstering the reliability of the simulation. The introduction of porous foam into the domain results in a significant enhancement of the freezing rate, with an increase of about 90.75 %. Furthermore, in scenarios without porous foam, the mixing of nano-powders and a surge in the radiation factor contribute to notable reductions in completion time, with decreases of approximately 12.52 % and 8 %, respectively. By combining all these techniques, a considerable reduction in solidification time can be achieved, amounting to around 91.46 %. This highlights the importance of a comprehensive approach in improving solidification efficiency. By improving the efficiency of cold storage units through these advanced techniques, this research contributes to the sustainable use of natural resources, highlighting the potential for reducing energy consumption and minimizing environmental impact