This paper deals with an integration of directly measured electrical parameters with data acquired by data communication from protections and terminals into an advanced monitoring system. Based on the periodic test, t...This paper deals with an integration of directly measured electrical parameters with data acquired by data communication from protections and terminals into an advanced monitoring system. Based on the periodic test, the authors of this paper present the possibility of an extended evaluation and more accurate analysis of transient and failure events. For periodical testing, as implemented during the commissioning of power plants in the Czech Republic, a monitoring system of electrical equipment has been used, to record the courses of important electrical parameters and thus, proving the proper functioning of complex technological systems in various operation modes. Data from monitoring system were used to prove the successful results of the test or as a base data for further analysis of failures. The monitoring system has proved itself as a very useful device also when recording unexpected failure events, the cause of which was very quickly and accurately detected by the follow-up analysis. Initially, only the voltage and current data from measuring transformers, analogue transducers and contact relays were used as input data for the monitoring system. After the implementation of new digital protection technology and controlling terminals with inner data recorder, the data from digital devices could be also utilized for the monitoring system.展开更多
A novel, simple, rapid, economic and hypersensitive method of measuring Cr3＋ is described in this paper. Cr3＋ could be oxidated to H2CrO6, which is extracted by n-C5H11OH, so a trace amount of chromium is measured d...A novel, simple, rapid, economic and hypersensitive method of measuring Cr3＋ is described in this paper. Cr3＋ could be oxidated to H2CrO6, which is extracted by n-C5H11OH, so a trace amount of chromium is measured directly by spectrometers, Sandra sensitivity is S=6.40×10^-3 ug.cm-2.展开更多
Graphene substrates have recently been found to generate Raman enhancement. Systematic studies using different Raman probes have been implemented, but one of the most commonly used Raman probes, rhodamine 6G （R6G）, ...Graphene substrates have recently been found to generate Raman enhancement. Systematic studies using different Raman probes have been implemented, but one of the most commonly used Raman probes, rhodamine 6G （R6G）, has yielded controversial results for the enhancement effect on graphene. Indeed, the Raman enhancement factor of R6G induced by graphene has never been measured directly under resonant excitation because of the presence of intense fluorescence backgrounds. In this study, a polarization-difference technique is used to suppress the fluorescence background by subtracting two spectra collected using different excitation laser polarizations. As a result, enhancement factors are obtained ranging between 1.7 and 5.6 for the four Raman modes of R6G at 611, 1,183, 1,361, and 1,647 cm-~ under resonant excitation by a 514.5 nm laser. By comparing these results with the results obtained under non-resonant excitation （632.8 nm） and pre-resonant excitation （593 nm）, the enhancement can be attributed to static chemical enhancement （CHEM） and tuning of the molecular resonance. Density functional theory simulations reveal that the orbital energies and densities for R6G are modified bv ~raphene dots.展开更多
文摘This paper deals with an integration of directly measured electrical parameters with data acquired by data communication from protections and terminals into an advanced monitoring system. Based on the periodic test, the authors of this paper present the possibility of an extended evaluation and more accurate analysis of transient and failure events. For periodical testing, as implemented during the commissioning of power plants in the Czech Republic, a monitoring system of electrical equipment has been used, to record the courses of important electrical parameters and thus, proving the proper functioning of complex technological systems in various operation modes. Data from monitoring system were used to prove the successful results of the test or as a base data for further analysis of failures. The monitoring system has proved itself as a very useful device also when recording unexpected failure events, the cause of which was very quickly and accurately detected by the follow-up analysis. Initially, only the voltage and current data from measuring transformers, analogue transducers and contact relays were used as input data for the monitoring system. After the implementation of new digital protection technology and controlling terminals with inner data recorder, the data from digital devices could be also utilized for the monitoring system.
文摘A novel, simple, rapid, economic and hypersensitive method of measuring Cr3＋ is described in this paper. Cr3＋ could be oxidated to H2CrO6, which is extracted by n-C5H11OH, so a trace amount of chromium is measured directly by spectrometers, Sandra sensitivity is S=6.40×10^-3 ug.cm-2.
文摘Graphene substrates have recently been found to generate Raman enhancement. Systematic studies using different Raman probes have been implemented, but one of the most commonly used Raman probes, rhodamine 6G （R6G）, has yielded controversial results for the enhancement effect on graphene. Indeed, the Raman enhancement factor of R6G induced by graphene has never been measured directly under resonant excitation because of the presence of intense fluorescence backgrounds. In this study, a polarization-difference technique is used to suppress the fluorescence background by subtracting two spectra collected using different excitation laser polarizations. As a result, enhancement factors are obtained ranging between 1.7 and 5.6 for the four Raman modes of R6G at 611, 1,183, 1,361, and 1,647 cm-~ under resonant excitation by a 514.5 nm laser. By comparing these results with the results obtained under non-resonant excitation （632.8 nm） and pre-resonant excitation （593 nm）, the enhancement can be attributed to static chemical enhancement （CHEM） and tuning of the molecular resonance. Density functional theory simulations reveal that the orbital energies and densities for R6G are modified bv ~raphene dots.
