In recent years, the diode laser (810 nm) has been used for root canal disinfection, which plays an important role in endodontic therapy. This study was undertaken to evaluate disinfecting ability of a experimentally infected canals primary teeth. Human retained mandibular anterior teeth without apical foramen resorption were selected and contaminated with Enterococcus faecalis 21 days. The specimens randomly divided into four groups: negative group (no treatment), positive (5.25% NaOCl),...

Nanosecond-level transient electromagnetic disturbance (TED), including very fast overvoltage caused by operation of disconnectors, high-altitude pulse, and many other transients may interfere or even damage the electrical equipment. As one main protective equipment, performance metal-oxide surge arresters (MOAs) under nanosecond-level TED should be investigated then compared with that microsecond-level TED, especially lightning impulse. Based on a testing platform containing 400-kV pulse...

To investigate the high-altitude electromagnetic pulse (HEMP) immunity of electrical equipment in operation, a 10-kV transmission line (TL) experimental platform is built this paper. The conducted transient disturbance (TED) could be injected to TL with power on or off. TED produced by pulsed current injection (PCI) generator, whose rise time less than 20 ns and full width at half maximum range 500 ~ 550 short-circuit state 60 Ω resistor. On other hand, equivalently designed cross section...

The existing models of the Metal-Oxide arresters (MOA) have difficulty covering behavior prediction under surges with front time ranging from microseconds to nanoseconds. This brief presents an equation-based dynamic nonlinear model and its circuit implementation, which can describe MOA in a wide range frequencies amplitudes consideration piecewise nonlinearity characteristics. be easily constructed based on manufacturer's data multiplication factor table for characteristic. Two types used...

Metal-oxide arresters (MOA) are widely used to protect equipment against transient electromagnetic disturbances (TED) like very fast overvoltage (VFTO), high-altitude pulse (HEMP), lightning pulse, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">et al.</i> Researches on the performance of MOA under microsecond level rise-time TED abundant, such as pulse. However, when is subjected at nanosecond level, voltage/current responses not fully...

The abnormal rise in contact temperature switchgear may lead to overheating or even explosion. It is necessary monitor the real ensure safety and stability of switchgear. accurate measurement still a problem, continuous state cannot be assessed accurately by monitor. In this paper, particular installation scheme sensor put forward calculation algorithm for tulip contacts measured bus bar time based on artificial neural network (ANN) established. An electromagnetic-thermal-fluid coupled...

Geo-magnetically induced currents (GICs) have at-4 tracted more attention since many Ultra-High Voltage (UHV) 5 transmission lines been built, or are going to be built in 6 the world.However, when calculating GICs based on classi-7 cal model, some input parameters, such as earth conductivity 8 and dc resistances of grid, uncertain very hard 9 determined advance.Taking this into account, uncertainty 10 quantification (UQ) model geo-electric fields is pro-11 posed paper.The UQ maximums 12...

The electromagnetic time reversal (EMTR) method has recently shown a novel advantage in locating faults along transmission lines. Under the ideal condition for EMTR, key parameters line between direct and reversed phases are assumed to be identical. Thus, fault position can pinpointed via cross-correlation matching theory. However, due natural geographical causes, vary line; therefore, accurately obtaining is difficult. In this article, we first investigate impact of uncertain on performance...

Modeling the geomagnetic induction in pipeline networks is essential for risk assessment and management of disturbances. The induced geoelectric field (GEF) usually spatially nonuniform, depending on distribution variation earth conductivity. However, few studies have been conducted complex with nonuniform GEF. In this article, a calculation model GEF proposed by utilizing modified equivalent-pi circuits. Then, used to investigate pipe-to-soil potentials geomagnetically currents network...

Self-consistency between Compton electrons and electromagnetic (EM) fields is an important physical mechanism in the generation propagation of early-time high-altitude EM pulse (HEMP). This article develops iterative self-consistent HEMP simulation scheme based on high-frequency approximation (HFA) algorithms. The effect decoupled neglected first iteration then taken into account by considering results field as independent fields, which affect next iteration. computation can be improved up...

Due to the difficulty in collecting samples of certain effect levels, class imbalance problem is a challenging issue vulnerability assessment. The would cause deviation likelihood function and thus deviate result Conventional assessment method ignoring it lead over- or under-estimation. In this article, we propose improved kernel density estimation (IKDE) address issue. proposed first calculates probability each level sample. Then, spatial characteristics are introduced reduce impact...

Based on the framework of quantification margins and uncertainties (QMU) method, a distribution-free QMU method is proposed for vulnerability evaluation electrical electronic equipment excited by transient electromagnetic disturbances. The can provide comprehensive considering stress strength with uncertainties. represented induced responses conductors, quantified occurrence probability failure obtained from experiment. quantile-based metric take account inherent characteristics strength, as...

S62 operations inside the gas-insulated substations (GIS) can stimulate transient radiated electromagnetic fields in space, which cause great damages to power equipment, especially for secondary device. Therefore, it's of vital importance investigate regularities such switching and master their main characteristics. Above all, this paper presents design measurement system E-fields GIS. Then, many on-site experiments were conducted, based on test results analyzed separately time domain,...

This article presents a time-domain macromodeling algorithm for buried transmission lines subject to coupling of an incident field and terminated with linear nonlinear loads. Different from overhead lines, the determination transient ground admittance is great importance due complexity analytical expressions necessity assuring good approximation over wide frequency range. The proposed macromodel adopts analog behavioral modeling (ABM) library Spice solvers model frequency-dependent line...

Methods based on electromagnetic time reversal (EMTR) have recently demonstrated promising results. In particular, EMTR, as a correlation estimator metric, has offered quantitative definition for fault location candidates. As the already obtains system transfer functions by simulating occurrences, these are subsequently correlated with fault-generated function. Therefore, it is necessary to explore analysis related pre-fault processing of this metric. Firstly, impact impedance mismatch...

This brief presents a behavioral macromodeling method for electronic or electrical interconnected systems, when there are frequency-characterized interconnects loaded by nonlinear terminations in systems. Analog modeling (ABM) was leveraged to capture frequency-dependent characteristics of multiconductor and properties terminations. Black-box macromodels were developed from the external mathematical behavior parts, real systems could be simulated SPICE circuit solver. Also, several critical...

This letter summarizes the existing test methods for protective devices and waveforms of conducted transient electromagnetic disturbance in different standards. However, they mainly focus on testing residual current or response behaviors coaxial protector. To quantify performance protection used power distribution system excited by transients, an optimal method is then proposed. The setup consists a pulse generator, absorption resistor, transmission lines, measurement system. results...

This paper presents an efficient statistical method for multivariable uncertainty qualification of transmission line field-to-line coupling. Random inputs cause uncertain responses at the ports line. Both internal variables due to geometrical parameters and external interference electromagnetic field should be taken into account. Stochastic collocation (SC) allows a fast simulation quantification analysis by polynomial approximation based on original deterministic calculation. SC has similar...

Recent researches about the spatial distribution and statistical results of high-altitude nuclear electromagnetic pulse (HEMP) put forwards requirements for efficiency simulation. However, simulation HEMP with consideration self-consistency was complex time-consuming including interaction between electrons (EM) fields. An efficient iterative scheme proposed in this paper, EM fields were decoupled simulated separately. The self-consistent effect neglected first iteration then taken into...