A compilation of global bio-optical in situ data for ocean colour satellite applications – version three

A global in situ data set for validation of ocean colour products from the ESA Ocean Colour Climate Change Initiative (OC-CCI) is presented. This version of the compilation, starting in 1997, now extends to 2021, which is important for the validation of the most recent satellite optical sensors such as Sentinel 3B OLCI and NOAA-20 VIIRS. The data set comprises in situ observations of the following variables: spectral remote-sensing reflectance, concentration of chlorophyll-a, spectral inherent optical properties, spectral diffuse attenuation coefficient, and total suspended matter. Data were obtained from multi-project archives acquired via open internet services or from individual projects acquired directly from data providers. Methodologies were implemented for homogenization, quality control, and merging of all data. Minimal changes were made on the original data, other than conversion to a standard format, elimination of some points, after quality control and averaging of observations that were close in time and space. The result is a merged table available in text format. Overall, the size of the data set grew with 148 432 rows, with each row representing a unique station in space and time (cf. 136 250 rows in previous version; Valente et al., 2019). Observations of remote-sensing reflectance increased to 68 641 (cf. 59 781 in previous version; Valente et al., 2019). There was also a near tenfold increase in chlorophyll data since 2016. Metadata of each in situ measurement (original source, cruise or experiment, principal investigator) are included in the final table. By making the metadata available, provenance is better documented and it is also possible to analyse each set of data separately. The compiled data are available at https://doi.org/10.1594/PANGAEA.941318 (Valente et al., 2022)

A compilation of global bio-optical in situ data for ocean colour satellite applications – version three

A global in situ data set for validation of ocean colour products from the ESA Ocean Colour Climate Change Initiative (OC-CCI) is presented. This version of the compilation, starting in 1997, now extends to 2021, which is important for the validation of the most recent satellite optical sensors such as Sentinel 3B OLCI and NOAA-20 VIIRS. The data set comprises in situ observations of the following variables: spectral remote-sensing reflectance, concentration of chlorophyll-a, spectral inherent optical properties, spectral diffuse attenuation coefficient, and total suspended matter. Data were obtained from multi-project archives acquired via open internet services or from individual projects acquired directly from data providers. Methodologies were implemented for homogenization, quality control, and merging of all data. Minimal changes were made on the original data, other than conversion to a standard format, elimination of some points, after quality control and averaging of observations that were close in time and space. The result is a merged table available in text format. Overall, the size of the data set grew with 148 432 rows, with each row representing a unique station in space and time (cf. 136 250 rows in previous version; Valente et al., 2019). Observations of remote-sensing reflectance increased to 68 641 (cf. 59 781 in previous version; Valente et al., 2019). There was also a near tenfold increase in chlorophyll data since 2016. Metadata of each in situ measurement (original source, cruise or experiment, principal investigator) are included in the final table. By making the metadata available, provenance is better documented and it is also possible to analyse each set of data separately. The compiled data are available at https://doi.org/10.1594/PANGAEA.941318 (Valente et al., 2022)

Nowa koncepcja transformatorów nadprzewodnikowych z taśm HTS 2G

The new 2G HTS tapes with high critical current and high resistivity in the normal state allow to build low-cost transformers with high short-circuit strength for the low and medium power distribution substations. The authors consider that currently the best chance of building have transformers, which rated currents of their windings do not exceed or slightly exceed the critical current of used superconducting tapes. Such units could be the low or medium voltage transformers with power less than 10 MVA, where the high voltage winding can be made with single HTS tape while the low voltage winding can also be made of single HTS tape or two – three tapes connected in parallel. This eliminates the need of tape transposition or application of the Roebel’s cable. Superconducting transformers could stabilize the low or medium power network and increase the connectivity of renewable and dispersed energy sources. The article presents an analysis of the possibility of using the low and medium voltage superconducting transformers. Such units could be e.g transformers working with renewable energy sources.Nowe taśmy nadprzewodnikowe 2G HTS o wysokim prądzie krytycznym i wysokiej rezystywności w stanie rezystywnym pozwalają na budowę transformatorów o wysokiej odporności na zwarcia dla sieci dystrybucyjnych niskich i średnich energii. Obecnie największe szanse na budowę mają transformatory, których znamionowe prądy uzwojeń nie przekraczają lub nieco przekraczają wartości prądu krytycznego zastosowanych taśm nadprzewodnikowych. Takimi jednostkami mogą być transformatory niskiego lub średniego napięcia o mocy poniżej 10 MVA, gdzie uzwojenie wysokonapięciowe może być wykonane pojedynczą taśmą HTS, a uzwojenie niskonapięciowe może być również wykonane z pojedynczej taśmy HTS lub dwóch - trzech taśm połączonych równolegle. Eliminuje to konieczność transpozycji taśm a tym samym zastosowania kabla Roebel. Zastosowanie transformatorów nadprzewodnikowych mogłoby ustabilizować sieć energetyczną niskiego i średniego napięcia i zwiększyć zdolność łączeniową odnawialnych i rozproszonych źródeł energii

Fault Current Limitation by 2G HTS Superconducting Transformer - Experimental Investigation

Transformers represent one of the oldest and most mature elements in a power transmission and distribution network. The new superconducting transformers are smaller and lighter than conventional ones and they have lower power losses, too. Also, the new 2G superconducting tapes with high resistivity in the normal state allow to build transformers with high short-circuit strength. The short-circuit current limiting feature of the superconducting transformer, which is the most important benefit of replacing conventional windings by superconducting ones, provides protection and significantly reduces the wear and tear of circuit breakers and other substation power equipment. This paper describes the design and experimental investigations results of a model of a 1-phase, 8.8 kVA superconducting transformer with windings made of 2G HTS tape. A special regard is given to the ability of the device's superconducting winding to limit the short-circuit current, in particular its equivalent resistance in normal state at a temperature of 77 K (i.e. resistance of the resistive layers of the HTS tape just after transition to the non-superconducting state)

Superconducting electric machines in watercraft

Superconductors, especially high temperature superconductors (HTS) are used in electric machines. Superconducting generators and motors have smaller mass and overall dimensions in comparison to conventional machines. Because of these specific quality that solutions are interested for ship propulsion applications. Current density in HTS superconducting winding may be two orders of magnitude higher than in copper windings, which allows to reach two times higher magnetic field density in the gap of synchronous machine, even without iron in the rotor and slots in the stator of the motor. Such design of synchronous machine can substantially reduce the distortion of current and voltage waveforms, as well as the acoustic effects. The construction without iron in rotor and higher magnetic induction makes the superconducting machine, with cooling system, several times lighter than conventional ones. The electric machines could be used in ships and airplanes where smaller dimensions and weight of propulsion equipment results in growth of ship displacement and cargo space. In ship propulsion supplied by generator with frequency converter, high speed generators e.g. 16 000 rpm (800 Hz) and low speed motors e.g. 230 rpm (115 Hz) are preferred for big weight decreasing. Paper presents basic knowledge about superconductors, the construction principles of electric superconducting devices and the examples of generators and motors with HTS winding. The parameters of these superconductor generators and motors were described too

Superconducting Devices for Power Engineering

The paper presents the current state of research on superconducting devices for the electrical power system, i.e. transformers, fault-current limiters, and energy storages. In particular, it describes scientific achievements of the Laboratory of Superconducting Technologies of Electrotechnical Institute. The development of distributed and renewable energy sources, as well as the increasing number of receivers with low power factor will rise interest in superconducting fault-current limiters and superconducting transformers rated below 1 MVA. Previous studies were focused on the largest power transformers and highest current superconducting fault-current limiters. ReBCO coated conductors allow to build efficient superconducting AC devices. Superconducting tape of a layered structure (second generation HTS tape) enables the construction of transformer rated up to a few MVA without the usage of parallel conductors. Relatively high resistance of the tape in normal state allows to build fault-current limiters and fault-current limiting transformers. Superconducting transformers and superconducting fault-current limiters can help to increase connected power of distribution stations and thereby accelerate development of renewable energy sources

Polysilsesquioxane (POSS)-linked imidazole-based carbene and phosphine ligands for transition metal catalysts

\u3cp\u3ePolyhedral oligomeric silsesquioxanes (POSS) linked ligand of the general formula (I) L [(R 1a ) n-1 (SiO 1,5 ) n R 2a ] k [(R 1b ) n-1 SiO 1,5 ) n R 2b ] l [(R 1c ) n-1 SiO 1,5 ) n R 2c ] m (I) in which (R 1a,b,c ) n-1 (SiO 1,5 ) n is a polyhedral oligomeric silsesquioxanes (POSS) with n = 4, 6, 8,10, 12, 14, 16 or 18 and R 1a , R 1b ,R 1c is each independently selected from the group consisting of same or different branched or linear C 1 -C 20 alkyl chains, cyclo alkyl, C 1 -C 20 alkoxy, aryl, aryloxy, heteroaryl and arylalkyl groups, k, I, m is 0 or 1 provided that k+l+m ¥ 1, R 2a , R 2b , R 2c is a spacer that binds the polyhedral oligomeric silsesquioxane (POSS) to the ligand L and ligand L is an uncharged electron donor.\u3c/p\u3

Polyhedral oligomeric silsesquioxane (poss)-linked ligands

Polyhedral oligomeric silsesquioxanes (POSS) linked ligand of the general formula (I): L [(R1a)n-1(SiO1,5)n R2a ]k [(R1b)n-1SiO1,5)n R2b ]| [(R1C)n-1SiO1,5)n R2c ]m in which (R1a,b,c)n-1(SiO1,5)n is a polyhedral oligomeric silsesquioxanes (POSS) with n = 4, 6, 8,10, 12, 14, 16 or 18 and R1a, R1b,R1c is each independently selected from the group consisting of same or different branched or linear C1-C20 alkyl chains, cyclo alkyl, C1-C20 alkoxy, aryl, aryloxy, heteroaryl and arylalkyl groups, k, l, m is 0 or 1 provided that k+l+m = 1, R2a, R2b, R2c is a spacer that binds the polyhedral oligomeric silsesquioxane (POSS) to the ligand L and ligand L is an uncharged electron donor