The doubly-fed induction generator (DFIG) is considered to provide a low-reactance path in the negative-sequence system and naturally comply with requirements on the negative-sequence reactive ...current in emerging grid codes. This paper shows otherwise and how the control strategy of converters plays a key role in the formation of the active and reactive current components. After investigating the existing control strategies from the perspective of grid code compliance and showing how they fail in addressing emerging requirements on the negative-sequence reactive current, we propose a new coordinated control strategy that complies with reactive current requirements in grid codes in the positive- and negative-sequence systems. The proposed method fully takes advantage of the current and voltage capacities of both the rotor-side converter (RSC) and grid-side converter (GSC), which enables the grid code compliance of the DFIG under unbalanced three-phase voltages due to asymmetrical faults. The mathematical investigations and proposed strategy are validated with detailed simulation models using the Electric Power Research Institute (EPRI) benchmark system. The derived mathematical expressions provide analytical clarifications on the response of the DFIG in the negative-sequence system from the grid perspective.
I reflect in this essay about the black women´s solitude subject-matter, from
readings and interpretations of video clip “A solida o da mulher preta (2018)”, by Nega Fya. I do
it, considering our ...solitude as a intersectional problem, based on Carla Akotirene (2018), and
having acess to Claudia Pacheco´s (2013) research, wich shows how the affective prefereces are
regulated by racial distinctions. I apprise, when reading the clip, the images represented by the
lyrics of the song and performances. I betake also psychoanalic readings done by Grada Kilomba
(2019) and Neusa Santos (1995) to problematize the black women´s speech, as well as the daily
racism episodes observed in the text.
Reflito neste ensaio a respeito do tema solidão da mulher negra, a partir de leituras e interpretações do videoclipe Solidão da mulher preta (2018) de Nega Fya. Faço isso considerando a nossa solidão como um problema de ordem interseccional, conforme é discutido por Carla Akotirene (2018) e acionando a pesquisa de Ana Claudia Pacheco (2013) que mostra como as preferências afetivas são reguladas pelos distintivos raciais. Considero, na leitura do videoclipe as imagens representadas a partir da letra da canção e das performances. Lanço mão de leituras psicanalíticas feitas por Grada Kilomba (2019) e Neusa Santos Souza (1995) para problematizar sobre a fala da mulher negra, bem como sobre os episódios de racismo cotidiano que resgato no texto.
The Zambezi Belt located in southern Zambia and northern Zimbabwe forms part of the E–W-trending Kuunga orogen associated with the amalgamation of Gondwana supercontinent. The belt consists of a ...crystalline basement unconformably overlain by a supracrustal sequence of meta-pelites/psammites, calc-silicates, meta‑carbonates, and magmatic rocks. Monazite-bearing meta-pelites are distinguished by petrography, geothermobarometry, monazite chemistry, and detrital provenance. The studied samples include six garnet-bearing schists with biotite, plagioclase, quartz, muscovite ± staurolite ± kyanite from the Nega Formation, and three kyanite-mica schists with chlorite, quartz, and accessory rutile, ilmenite, tourmaline from the Chipongwe Formation. Phase equilibria modelling and isopleth geothermobarometry identified Barrovian-type medium-T/ medium-P facies peak conditions of 570–665 °C/ 6.5–9 kbar on garnet-bearing schists, and 600–663 °C/ ~8.8–12 kbar on kyanite-mica schists. Evidence from detrital geochronology suggests that the two formations are stratigraphically equivalent, but electron microprobe dating on monazite suggests they underwent different tectonothermal histories. Monazite ages indicate metamorphism and crustal growth from ~650–579 Ma in 3 of the garnet-bearing schists of the Nega Formation, and ~ 550–500 Ma in one of the kyanite-mica schists of the Chipongwe Formation. Dating of detrital zircon by LA-ICP-MS indicates local and distal sediment sources including Neoarchean to Paleoproterozoic (2633–1800 Ma) and Meso- to Neoproterozoic (1700–852 Ma). A tectonic cycle of burial metamorphism to exhumation is indicated by clockwise P-T-t paths along different geothermal gradients. The rock units were brought together during collision between the Congo and Kalahari Cratons and final assembly of Gondwana.
•The Zambezi Belt is part of the Kuunga Orogen formed during Gondwana assembly•Metapelites are distinguished by monazite chemistry and detrital provenance•P-T conditions of 570–665 °C/6–9 kbar and 600–663 °C/8.8–12 kbar were obtained•The rocks underwent metamorphism at 〜650–579 Ma and 550–500 Ma respectively•The rocks evolved along different geotherms prior to final Gondwana assembly
In this paper, we present three secondary methods for constructing bent–negabent functions under the frameworks of the indirect sum construction (proposed by Carlet in 2004), the modified indirect ...sum construction (proposed by Hod
z
ˇ
i
c
´
et al in Des Codes Cryptogr 88(10):2007–2035, 2020) and Rothaus’ construction. We first give a construction of bent–negabent functions by using the indirect sum construction, and specify some sufficient conditions on initial functions so that these constructed functions are provably outside the completed Maiorana–McFarland class. Here, we correct some results on the construction of bent–negabent functions proposed by Zhang et al. (IEEE Trans Inf Theory 61(3):1496–1506, 2015). Then, we investigate the nega–Hadamard transform of the composition of a multi-output function and a Boolean function. Using this tool, with initial primary bent–negabent functions, we analyze and find out the necessary and sufficient conditions for the modified indirect sum construction and Rothaus’ construction to generate bent–negabent functions. Furthermore, by developing methods to obtain initial functions satisfying the required necessary and sufficient conditions, we propose several constructions of bent–negabent functions under these two frameworks of the secondary constructions.
It has been shown that all the known binary Golay complementary sequences of length
2
m
can be obtained by a single binary Golay complementary array of dimension
m
and size
2
×
2
×
⋯
×
2
which can be ...represented by a Boolean function. However, the construction of new binary Golay complementary sequences of length
2
m
or Golay complementary arrays remains an open problem. In this paper, we studied the Walsh spectrum distribution and the nega spectrum distribution of the binary or quaternary Golay (Type-I) complementary array. Then, the Walsh spectrum of the binary Type-II complementary array and the nega spectrum of the binary Type-III complementary array are investigated as well. At last, the Walsh spectrum of a binary array in a complementary array set of size 4 is discussed. This work proves that binary and quaternary complementary arrays above-mentioned can only be constructed from (generalized) Boolean functions satisfying spectral values given in this paper. For instance, a binary Type-I complementary array must be bent for even
m
and near-bent for odd
m
with respect to the Walsh spectrum, and it must be negaplateaued, nega-bent or negalandscape with respect to the nega spectrum. On the other hand, constructions of new binary and quaternary complementary arrays may help us find new (generalized) Boolean functions with specific condition, such as bent or nega-bent functions.
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