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排序方式: 共有511条查询结果,搜索用时 26 毫秒
501.
Bert Renders Koen De Gussemé Wouter R. Ryckaert Lieven Vandevelde 《Electric Power Systems Research》2009
The steadily growing share of converter-connected distributed generators, combined with a large amount of nonlinear and unbalanced loads connected to the electric power system, has led to a degraded power quality. Both harmonic voltage and harmonic current distortion may cause many unfavourable effects on the power system. However, the converter-connected distributed generators can be redesigned to have a positive effect on the distortion of the grid voltage. Two different approaches can be discerned. At the one hand, distributed generation units can be controlled to synthesize a resistive load for harmonic voltage components. This approach is called harmonic voltage damping. At the other hand, if the polluting current of an adjacent nonlinear load is measured and added to the control loop, the converter-connected distributed generator is able to compensate all harmonic current components of the nonlinear load. This approach is referred to as harmonic current compensation. In this paper, a control strategy for a converter-connected distributed generator is extended with a harmonic voltage damping function and a harmonic current compensation function. Experimental tests show that the voltage distortion of the grid voltage can be significantly improved. 相似文献
502.
Koen Vandewal Abay Gadisa Wibren D. Oosterbaan Sabine Bertho Fateme Banishoeib Ineke Van Severen Laurence Lutsen Thomas J. Cleij Dirk Vanderzande Jean V. Manca 《Advanced functional materials》2008,18(14):2064-2070
Photocurrent generation by charge‐transfer (CT) absorption is detected in a range of conjugated polymer–[6,6]‐phenyl C61 butyric acid methyl ester (PCBM) based solar cells. The low intensity CT absorption bands are observed using a highly sensitive measurement of the external quantum efficiency (EQE) spectrum by means of Fourier‐transform photocurrent spectroscopy (FTPS). The presence of these CT bands implies the formation of weak ground‐state charge‐transfer complexes in the studied polymer–fullerene blends. The effective band gap (Eg) of the material blends used in these photovoltaic devices is determined from the energetic onset of the photocurrent generated by CT absorption. It is shown that for all devices, under various preparation conditions, the open‐circuit voltage (Voc) scales linearly with Eg. The redshift of the CT band upon thermal annealing of regioregular poly(3‐hexylthiophene):PCBM and thermal aging of poly(phenylenevinylene)(PPV):PCBM photovoltaic devices correlates with the observed drop in open‐circuit voltage of high‐temperature treated versus untreated devices. Increasing the weight fraction of PCBM also results in a redshift of Eg, proportional with the observed changes in Voc for different PPV:PCBM ratios. As Eg corresponds with the effective bandgap of the material blends, a measurement of the EQE spectrum by FTPS allows us to measure this energy directly on photovoltaic devices, and makes it a valuable technique in the study of organic bulk heterojunction solar cells. 相似文献
503.
Liu Yang Koen H. van Dam Arnab Majumdar Bani Anvari Washington Y. Ochieng Lufeng Zhang 《建筑学研究前沿(英文版)》2019,8(4):429-453
In order to achieve holistic urban plans incorporating transport infrastructure, public space and the behavior of people in these spaces, integration of urban design and computer modeling is a promising way to provide both qualitative and quantitative support to decisionmakers. This paper describes a systematic literature review following a four-part framework. Firstly, to understand the relationship of elements of transport, spaces, and humans, we review policy and urban design strategies for promoting positive interactions. Secondly, we present an overview of the integration methods and strategies used in urban design and policy discourses. Afterward, metrics and approaches for evaluating the effectiveness of integrated plan alternatives are reviewed. Finally, this paper gives a review of state-of-the-art tools with a focus on seven computer simulation paradigms. This article explores mechanisms underlying the complex system of transport, spaces, and humans from a multidisciplinary perspective to provide an integrated toolkit for designers, planners, modelers and decision-makers with the current methods and their challenges. 相似文献
504.
Composition,Granular Structure,and Pasting Properties of Native Starch Extracted from Plectranthus edulis (Oromo dinich) Tubers 下载免费PDF全文
505.
506.
Shinichi Saitoh Koen Van Wijk Osamu Nakajima 《International journal of molecular sciences》2021,22(18)
Metabolic syndrome results from multiple risk factors that arise from insulin resistance induced by abnormal fat deposition. Chronic inflammation owing to obesity primarily results from the recruitment of pro-inflammatory M1 macrophages into the adipose tissue stroma, as the adipocytes within become hypertrophied. During obesity-induced inflammation in adipose tissue, pro-inflammatory cytokines are produced by macrophages and recruit further pro-inflammatory immune cells into the adipose tissue to boost the immune response. Here, we provide an overview of the biology of macrophages in adipose tissue and the relationship between other immune cells, such as CD4+ T cells, natural killer cells, and innate lymphoid cells, and obesity and type 2 diabetes. Finally, we discuss the link between the human pathology and immune response and metabolism and further highlight potential therapeutic targets for the treatment of metabolic disorders. 相似文献
507.
Ulrike Vogel Dr. Matthieu Da Costa Carlos Alvarez Quispe Robin Stragier Dr. Henk-Jan Joosten Dr. Koen Beerens Prof. Dr. Tom Desmet 《Chembiochem : a European journal of chemical biology》2023,24(23):e202300549
A promiscuous CDP-tyvelose 2-epimerase (TyvE) from Thermodesulfatator atlanticus (TaTyvE) belonging to the nucleotide sugar active short-chain dehydrogenase/reductase superfamily (NS-SDRs) was recently discovered. TaTyvE performs the slow conversion of NDP-glucose (NDP-Glc) to NDP-mannose (NDP-Man). Here, we present the sequence fingerprints that are indicative of the conversion of UDP-Glc to UDP-Man in TyvE-like enzymes based on the heptagonal box motifs. Our data-mining approach led to the identification of 11 additional TyvE-like enzymes for the conversion of UDP-Glc to UDP-Man. We characterized the top two wild-type candidates, which show a 15- and 20-fold improved catalytic efficiency, respectively, on UDP-Glc compared to TaTyvE. In addition, we present a quadruple variant of one of the identified enzymes with a 70-fold improved catalytic efficiency on UDP-Glc compared to TaTyvE. These findings could help the design of new nucleotide production pathways starting from a cheap sugar substrate like glucose or sucrose. 相似文献
508.
509.
Siham Benramdane Joni De Loose Olivier Beyens Yentl Van Rymenant Dr. Gwendolyn Vliegen Prof. Koen Augustyns Prof. Hans De Winter Prof. Ingrid De Meester Prof. Pieter Van der Veken 《ChemMedChem》2022,17(15):e202200097
Vildagliptin is a marketed DPP4 inhibitor, used in the management of type 2 diabetes. The molecule also has notable DPP8/9 affinity, with some preference for DPP9. Therefore, we aimed to use vildagliptin as a starting point for selective DPP8/9 inhibitors, and to engineer out the parent compound's DPP4-affinity. In addition, we wanted to identify substructures in the obtained molecules that allow their further optimization into inhibitors with maximal DPP9 selectivity. Various 2S-cyanopyrrolidines and isoindoline were investigated as P1 residues of vildagliptin analogs. The obtained set was expanded with derivatives bearing O-substituted, N-(3-hydroxyadamantyl)glycine moieties at the P2 position. In this way, representatives were discovered with DPP8/9 potencies comparable to the parent molecule, but with overall selectivity towards DPP4, DPP2, FAP, and PREP. Furthermore, the most promising molecules in this series have a 4- to 7-fold preference for DPP9 over DPP8. Finally, a molecular dynamics study was carried out to maximize our insight into experimental selectivity data. 相似文献
510.
Shan Wang Myrte van Geffen Koen Venema Alex Mommers Daisy Jonkers Frederik-Jan van Schooten Roger Godschalk 《Molecular nutrition & food research》2023,67(9):2200574