Search results for "Control."
showing 10 items of 13063 documents
Sensitivity Analysis and Frequency Dynamics of Grid-Connected Converters with Virtual Inertia
2021
For the participation in the frequency control of the system, power converters can be controlled with different strategies and methods, sharing the common concept of virtual inertia capability. In this work, a sensitivity analysis of two main categories of converter controls with virtual inertia is presented. The considered schemes are a grid-following current vector control with additional virtual inertia block and a grid-forming control scheme based on virtual synchronous machine concept. A proper basis for the comparison is first assessed providing an analytical correlation between the control parameters of the two schemes. For the two control strategies, the sensitivity analysis of the …
Enhancement of hepatitis C virus RNA replication by cell culture-adaptive mutations.
2001
ABSTRACT Studies of the Hepatitis C virus (HCV) replication cycle have been made possible with the development of subgenomic selectable RNAs that replicate autonomously in cultured cells. In these replicons the region encoding the HCV structural proteins was replaced by the neomycin phosphotransferase gene, allowing the selection of transfected cells that support high-level replication of these RNAs. Subsequent analyses revealed that, within selected cells, HCV RNAs had acquired adaptive mutations that increased the efficiency of colony formation by an unknown mechanism. Using a panel of replicons that differed in their degrees of cell culture adaptation, in this study we show that adaptive…
Viral and cellular determinants of hepatitis C virus RNA replication in cell culture.
2003
Studies on the replication of hepatitis C virus (HCV) have been facilitated by the development of selectable subgenomic replicons replicating in the human hepatoma cell line Huh-7 at a surprisingly high level. Analysis of the replicon population in selected cells revealed the occurrence of cell culture-adaptive mutations that enhance RNA replication substantially. To gain a better understanding of HCV cell culture adaptation, we characterized conserved mutations identified by sequence analysis of 26 independent replicon cell clones for their effect on RNA replication. Mutations enhancing replication were found in nearly every nonstructural (NS) protein, and they could be subdivided into at …
Genome sequence of SeIV-1, a novel virus from the Iflaviridae family infective to Spodoptera exigua
2011
Analysis of the transcriptome of Spodoptera exigua larvae revealed the presence of several ESTs with homology to virus of the order Picornavirales and with the highest similarity to Infectious flacherie virus (Iflaviridae) that infects Bombyx mori larvae. Iflaviridae is a recently defined family of insect-infecting viruses that consist of positive single strand RNA genomes translated into a single polyprotein of around 3000 amino acids long. Using the sequence information derived from the obtained ESTs, we have completed the genomic sequence of this virus. The novel S. exigua iflavirus (SeIV-1) has a genome of 10.3 kb and codes for a 3222 aa polyprotein. Expression analysis has revealed the…
Regularity for nonlinear stochastic games
2015
We establish regularity for functions satisfying a dynamic programming equation, which may arise for example from stochastic games or discretization schemes. Our results can also be utilized in obtaining regularity and existence results for the corresponding partial differential equations. peerReviewed
Virskorekcijas pielietojamība tuvredzības progresijas novērtēšanā ortokeratoloģijas pacientiem
2022
Darbs ir uzrakstīts angļu valodā uz 93 lapaspusēm. Tas satur 49 attēlus, 24 tabulas un 95 atsauces uz literatūras avotiem. Šī darba mērķis ir pārbaudīt, vai virskorekcija ir derīga metode tuvredzības progresēšanas novērtēšanai ortokeratoloģijā. Hipotēze ir atrast lielākas izmaiņas gados jaunākiem pacientiem nekā pieaugušajiem, kā tas ir norādīts literatūrā. Pētījumā iekļauti 192 Eiropeīdās rases subjekti vecumā no 6 līdz 56 gadiem (vidēji 19,61±10,30). Izmantojot retrospektīvu analīzi, no objektīva BOZR kontaktlēcas parametra tiek iegūta virskorekcija (ORX). Jaunākiem cilvēkiem ir lielākas ORX vērtības, bet pieaugušajiem nav atšķirības (p<0,05). Vidēji tuvredzība progresēja par –0,18±0,44 D…
Experimental Validation of Maximum Constant Boost Control and Switching Frequency Optimal for three-phase Quasi-Z-Source Converters
2020
This paper presents a modified modulation scheme for quasi-Z-Source converters, based on the Maximum Constant Boost Control (MCBC) concept and Switching Frequency Optimal (SFO) as reference signal. The effectiveness of the proposed technique is validated by comparing the obtained results (in terms of AC harmonic content and voltage stress) with those carried out from traditional modulation schemes. For this reason, a test bench has been assembled and the benefits of the SFO MCBC modulation scheme have been valuated.
Decoupled control scheme of grid-connected split-source inverters
2017
Grid-connected power conversion systems for renewable energy sources must fulfill several requirements, e.g., the high efficiency, the reduced cost and complexity, and, quite often, the boost capabilities that is usually achieved using a front-end dc–dc boost converter before the inversion stage, leading to a two-stage architecture. Meanwhile, single-stage power conversion systems, which perform the boosting operation within the inversion one, offer some potential advantages, in terms of reducing the complexity and the volume of the whole system. Among several proposed options, the split-source inverter (SSI) has been recently proposed by Abdelhakim et al. as an alternative option with some…
视觉工作记忆中数量和精度的权衡关系是否受个体自发控制
2021
There is a negative correlation between the quality and quantity of memory representations in visual working memory, and this negative correlation is seen as a trade-off between quantity and quality. However, it is unclear whether this trade-off is entirely stimulus-driven or can be controlled voluntarily by individuals according to task demands, which has led to a debate on the mechanism of memory resource allocation. This paper systematically reviews the development of research on whether the trade-off between quantity and quality is subject to individual voluntary control, and point out this voluntary control is influenced by the exposure duration and working memory capacity, and some su…
Ontology and protocol secure for SCADA
2014
In this work, we present a semantic cyber security system and we study its semantic intelligent systems vulnerabilities, focusing on the semantic attacks. For resolving semantic problems we propose a security global solution for the new generation of SCADA systems. The proposed solution aims at protecting critical semantic SCADA processes from the effects of major failures and semantic vulnerabilities in the modern IT-SCADA network. We used a security block in the global network access point, security protocols deployed in different network (OSI) levels and security ontologies deployed in security devices. We used our mixed coordinates (ECC) cryptography solution, this is an encryption tech…