Electrospun Poly(styrene) Fibers as a Protection for the First- and the Second-Generation Grubbs’ Catalyst

The study presents a novel method for protection of the first- and the second-generation Grubbs’ catalyst, by incorporation in poly(styrene) fibers through electrospinning technique. Both catalysts are sensitive to the presence of the amine hardeners in the epoxy-based self-healing composites and require protection from deactivation to retain their ability to promote polymerization reaction of the healing agent. Comparison of healing efficiencies of both catalysts suggested that poly(styrene) fibers offer better protection and dispersion for the first-generation Grubbs’ catalyst, although all the samples exhibited high-healing efficiency. Difference in stereoselectivity between two catalysts was also indicated.     

New Digital Algorithm for Adaptive Reclosing Based on the Calculation of the Faulted Phase Voltage Total Harmonic Distortion Factor

This paper presents a new numerical algorithm suitable for determining adaptive dead time, and blocking automatic reclosing during permanent faults on overhead lines. It is based on terminal voltage input data processing. The decision if it is safe or not to reclose is determined by the voltage signal of faulted and tripped line phase using the total harmonic distortion factor calculated by discrete Fourier transform. The algorithm was successfully tested using signals recorded on the real power system. The tests demonstrate the ability of the presented algorithm to determine the secondary arc extinction time and to block unsuccessful automatic reclosing of high-voltage lines with permanent fault     

Distance protection and fault location utilizing only phase currentphasors

Two numerical algorithms for fault location and distance protection which use data from one end of a transmission line are presented. Both algorithms require only current signals as input data. Voltage signals are unnecessary for determining the unknown distance to the fault. The solution for the most frequent phase to ground fault is presented. The algorithms are relatively simple and easy to be implemented in the on-line application. The algorithms allow for accurate calculation of the fault location irrespective of the fault resistance and load. To illustrate the features of the new algorithms, steady-state and dynamic tests are presented     

Zeroth-order half-wave plates of LiNbO3 for integratedoptics applications at 1.55 μm

Reports on fabrication and characterization of the first zeroth-order half-wave plates of LiNbO₃ obtained by crystal ion slicing (CIS). Polarization rotation was demonstrated in 10-μm-thick freestanding LiNbO₃ films with 30-dB conversion ratios and negligible material loss. Polarization-independent performance was demonstrated in a hybrid-optic device comprising a CIS wave plate integrated with single-mode silica-based channel waveguides     

Numerical algorithm for adaptive autoreclosure and protection of medium-voltage overhead lines

In this paper, a new numerical algorithm for medium-voltage overhead lines, autoreclosure, is described. The subfunction of the autoreclosure scheme that would inhibit the first shot after detecting a solid fault (as compared with an arc fault) is evaluated and presented. It is based on one terminal data processing and it is derived in the time domain. In the algorithm the fault nature (arcing or arcless fault) is estimated using linear least error squares estimation technique. The arc, occurring on the fault point during arcing faults on overhead lines, is included in the problem consideration. In addition, by introducing the prefault load current in the existing model, better algorithm performances and a more reliable adaptive algorithm for autoreclosure are achieved. The algorithm is derived for the case of three-phase symmetrical fault. The results of the algorithm testing through computer simulation are presented. Particularly the algorithm sensitivity to arc elongation effects, supplying network parameters, and processing of the signals in the presence of harmonics are tested and analyzed.     

Numerical algorithm for overhead lines protection and disturbance records analysis

A new and very efficient numerical algorithm for overhead lines protection is presented. The algorithm particularly improves up-to-date solutions with regard to fault location, adaptive autoreclosure, detailed disturbance records analysis and fault data management. It is based on the two-terminal line currents and voltages acquisition. For this purpose, the synchronised sampling of all analogue input variables, that is, the application of the global positioning system/phasor measurement units, was assumed. The algorithm presented is derived in the spectral domain and based on the application of the discrete Fourier transform. The prerequisite for the successful adaptive autoreclosure functionality realisation was the suitable modelling of the electrical arc. The electrical arc was considered as a source of higher harmonics. These are included in the complete fault model, which was the starting point for the development of this new algorithm. One of the algorithm's sophisticated features is its ability to determine both the arc and the fault resistance. For the purpose of arc modelling, the results of high current laboratory testing are used. The algorithm is tested through computer-based simulation of a line connected to two active networks. On the basis of the results obtained, it is very realistic that the algorithm presented could be implemented in praxis in modern intelligent electronic devices