Doekle Yntema

Self-Capacitance and Resistive Losses of Saline-Water-Filled Inductors

Properties of water-filled inductors are relevant for underwater wireless energy transfer. The influence of the relative permittivity and resistivity of the core material on the impedance of an inductor can be modeled with a lumped parameter circuit. The relative permittivity of the core material has influence on the turn-to-core capacitance of the inductor. The resistivity of the core material has a linear relation with the resistance of the turn-to-turn capacitance. With this model, the influence of the conductivity on the quality factor of an inductor can be predicted. This is a helpful tool to find the optimal frequency at which the quality factor is maximum.

Alternating electric fields combined with activated carbon for disinfection of Gram negative and Gram positive bacteria in fluidized bed electrode system.

Strong electric fields for disinfection of wastewaters have been employed already for several decades. An innovative approach combining low strength (7 V/cm) alternating electric fields with a granular activated carbon fluidized bed electrode (FBE) for disinfection was presented recently. For disinfection performance of FBE several pure microbial cultures were tested: Bacillus subtilis, Bacillus subtilis subsp. subtilis, Enterococcus faecalis as representatives from Gram positive bacteria and Erwinia carotovora, Pseudomonas luteola, Pseudomonas fluorescens and Escherichia coli YMc10 as representatives from Gram negative bacteria. The alternating electric field amplitude and shape were kept constant. Only the effect of alternating electric field frequency on disinfection performance was investigated. From the bacteria tested, the Gram negative strains were more susceptible and the Gram positive microorganisms were more resistant to FBE disinfection. The collected data indicate that the efficiency of disinfection is frequency and strain dependent. During 6 h of disinfection, the decrease above 2 Log units was achieved with P. luteola and E. coli at 10 kHz and at dual frequency shift keying (FSK) modulated signal with frequencies of 10 kHz and 140 kHz. FBE technology appears to offer a new way for selective bacterial disinfection, however further optimizations are needed on treatment duration, and energy input, to improve effectiveness.