This paper focuses on advanced analysis techniques and design considerations of DC interference generated by HVDC electrodes during normal bipolar and temporary monopolar operations on neighboring metallic utilities, ...This paper focuses on advanced analysis techniques and design considerations of DC interference generated by HVDC electrodes during normal bipolar and temporary monopolar operations on neighboring metallic utilities, with a special emphasis on buried gas and oil pipelines. This study examines the level of pipeline corrosion, the safety status in the vicinity of exposed appurtenances and the impact of DC interference on the integrity of insulating flanges and impressed current cathodic protection (ICCP) systems. Computation results obtained for different soil models show that different soils can lead to completely different DC interference effects. The results and conclusions presented here can be used as a reference to analyze the severity of DC interference on pipelines due to proximate HVDC electrodes.展开更多
Crosslinked copolymers with single Li^+-ionic conductivity were prepared from oligo (oxyethylene) methacrylate (MEO_n), methacryloyl alkylsulfonic acid lithium (SAMLi), and oligo (oxyethylene) dimethacrylate (DMEO_n)....Crosslinked copolymers with single Li^+-ionic conductivity were prepared from oligo (oxyethylene) methacrylate (MEO_n), methacryloyl alkylsulfonic acid lithium (SAMLi), and oligo (oxyethylene) dimethacrylate (DMEO_n). Li^+-ionic conductivity of the copolymer is improved by crosslinking and presented as a function of polymerization degree (n) in MEO_n, comonomeric salt concentration (O/Li), and crosslinking degree. The crosslinked copolymer P (0.7 MEO_(14)-0.3DMEO_(14)-SHMLi) without other small molecular additives exhibits an optimum Li^+-ionic conductivity of 1.2×10^(-6) S/cm at 25℃. Dc polarization test in the cell composed of Li/copolymer/Li shows a constant dc ionic conductivity which closes gradually to the ac one with decreasing dc polarization potential.展开更多
Poly(vinylidene fluoride-hexafluropropylene)(PVDF-HFP)and poly(methyl methacrylate)(PMMA)-based gel polymer electrolytes(GPEs)comprising propylene carbonate and diethyl carbonate mixed plasticizer with variation of li...Poly(vinylidene fluoride-hexafluropropylene)(PVDF-HFP)and poly(methyl methacrylate)(PMMA)-based gel polymer electrolytes(GPEs)comprising propylene carbonate and diethyl carbonate mixed plasticizer with variation of lithium perchlorate(LiClO_(4))salt concentrations have been prepared using a solvent casting technique.Structural characterization has been carried out using XRD wherein diffraction pattern reveals the amorphous nature of sample up to 7.5 wt.%salt and complexation of polymers and salt have been studied by FTIR analysis.Surface morphology of the samples has been studied using scanning electron microscope.Electrochemical impedance spectroscopy in the temperature range 303-363K has been carried out for electrical conductivity.The maximum room temperature conductivity of 2.83×10^(-4) S cm^(-1) has been observed for the GPE incorporating 7.5 wt.%LiClO_(4).The temperature dependence of ionic conductivity obeys the Arrhenius relation.The increase in ionic conductivity with change in temperatures and salt content is observed.Transport number measurement is carried out by Wagner’s DC polarization method.Loss tangent(tanδ)and imaginary part of modulus(M″)corresponding to dielectric relaxation and conductivity relaxation respectively show faster relaxation process with increasing salt content up to optimum value of 7.5 wt.%LiClO_(4).The modulus(M″)shows that the conductivity relaxation is of non-Debye type(broader than Debye peak).展开更多
文摘This paper focuses on advanced analysis techniques and design considerations of DC interference generated by HVDC electrodes during normal bipolar and temporary monopolar operations on neighboring metallic utilities, with a special emphasis on buried gas and oil pipelines. This study examines the level of pipeline corrosion, the safety status in the vicinity of exposed appurtenances and the impact of DC interference on the integrity of insulating flanges and impressed current cathodic protection (ICCP) systems. Computation results obtained for different soil models show that different soils can lead to completely different DC interference effects. The results and conclusions presented here can be used as a reference to analyze the severity of DC interference on pipelines due to proximate HVDC electrodes.
文摘Crosslinked copolymers with single Li^+-ionic conductivity were prepared from oligo (oxyethylene) methacrylate (MEO_n), methacryloyl alkylsulfonic acid lithium (SAMLi), and oligo (oxyethylene) dimethacrylate (DMEO_n). Li^+-ionic conductivity of the copolymer is improved by crosslinking and presented as a function of polymerization degree (n) in MEO_n, comonomeric salt concentration (O/Li), and crosslinking degree. The crosslinked copolymer P (0.7 MEO_(14)-0.3DMEO_(14)-SHMLi) without other small molecular additives exhibits an optimum Li^+-ionic conductivity of 1.2×10^(-6) S/cm at 25℃. Dc polarization test in the cell composed of Li/copolymer/Li shows a constant dc ionic conductivity which closes gradually to the ac one with decreasing dc polarization potential.
文摘Poly(vinylidene fluoride-hexafluropropylene)(PVDF-HFP)and poly(methyl methacrylate)(PMMA)-based gel polymer electrolytes(GPEs)comprising propylene carbonate and diethyl carbonate mixed plasticizer with variation of lithium perchlorate(LiClO_(4))salt concentrations have been prepared using a solvent casting technique.Structural characterization has been carried out using XRD wherein diffraction pattern reveals the amorphous nature of sample up to 7.5 wt.%salt and complexation of polymers and salt have been studied by FTIR analysis.Surface morphology of the samples has been studied using scanning electron microscope.Electrochemical impedance spectroscopy in the temperature range 303-363K has been carried out for electrical conductivity.The maximum room temperature conductivity of 2.83×10^(-4) S cm^(-1) has been observed for the GPE incorporating 7.5 wt.%LiClO_(4).The temperature dependence of ionic conductivity obeys the Arrhenius relation.The increase in ionic conductivity with change in temperatures and salt content is observed.Transport number measurement is carried out by Wagner’s DC polarization method.Loss tangent(tanδ)and imaginary part of modulus(M″)corresponding to dielectric relaxation and conductivity relaxation respectively show faster relaxation process with increasing salt content up to optimum value of 7.5 wt.%LiClO_(4).The modulus(M″)shows that the conductivity relaxation is of non-Debye type(broader than Debye peak).
