Application of UPFC to Improve the LVRT Capability of Wind Turbine Generator

Variable speed wind turbine generators installation has been significantly increased worldwide in the last few years. Voltage sag at the grid side may call for the disconnection of the wind turbine from the grid as under such faults it may not comply with the recent developed grid codes for wind energy conversion systems (WECS). In this paper, a Unified Power Flow Controller (UPFC) is applied to improve the low voltage ride through (LVRT) capability of doubly fed induction generator (DFIG)-based WECS during voltage sag at the grid side. Simulation is carried out using MATLAB/Simulink software. Results show that UPFC can significantly improve the LVRT capability of DFIG-based WECS and hence maintaining wind turbine connection to the grid during certain levels of voltage sag at the grid side

Application of UPFC to Improve the FRT Capability of Wind Turbine Generator

Variable speed wind turbine generators installation has been significantly increased worldwide in the last few years. Faults at the grid side may call for the disconnection of the wind turbine from the grid as under such events, wind turbine generator (WTG) may not comply with the recent developed grid codes for wind energy conversion systems (WECS). In this paper, a unified power flow controller (UPFC) is applied to improve the fault ride through (FRT) capability of doubly fed induction generator (DFIG)-based WECS during voltage swell and voltage sag at the grid side. Simulation is carried out using MATLAB/Simulink software. Results show that UPFC can effectively improve the FRT capability of DFIG-based WECS and hence maintaining wind turbine connection to the grid during certain levels of voltage fluctuation at the grid side

Investigation of near flicker source impact on the dynamic performance of FCWECS

The number of full converter wind energy conversion system (FCWECS) connected to existing electricity grids has significantly increased worldwide during the last two decades. One of the common power quality issues associated with wind turbine generator (WTG) is the voltage flicker which can be caused due to wind gust. It is pivotal for the existing or the new construction of the WTG to comply with the power quality standards. Although, with the advance in WTG technology and control systems, the flicker due to wind speed fluctuation can be mitigated, flicker can still be caused as a result of load pulsation such as arc furnaces, resistive welding machines and compressors. In this paper, the near flicker source impact on the connected WTG performance is investigated and the compliance of the WTG with the recent grid codes under such disturbance is highlighted

Bottomonia Under Effect Three Inspired QCD Potentials in the Framework of Non-Relativistic Quark Model

In this paper, we have studied the spectrum of bottomonium mesons behavior under the effect of three types of potentials inspired by Quantum Chromodynamics. In addition, other properties like Hyperfine splitting behavior, and Fine splitting behavior have been studied. We used these potential models within the non-relativistic quark model to present this study. We found that our expectations are consistent with experimental data and other theoretical works as well we presented new conclusions regarding the spectrum of unseen bottomonium states for S, P, and D-wave bottomonia. And we have expected other their characteristics

A global experience-sampling method study of well-being during times of crisis : The CoCo project

We present a global experience-sampling method (ESM) study aimed at describing, predicting, and understanding individual differences in well-being during times of crisis such as the COVID-19 pandemic. This international ESM study is a collaborative effort of over 60 interdisciplinary researchers from around the world in the “Coping with Corona” (CoCo) project. The study comprises trait-, state-, and daily-level data of 7490 participants from over 20 countries (total ESM measurements = 207,263; total daily measurements = 73,295) collected between October 2021 and August 2022. We provide a brief overview of the theoretical background and aims of the study, present the applied methods (including a description of the study design, data collection procedures, data cleaning, and final sample), and discuss exemplary research questions to which these data can be applied. We end by inviting collaborations on the CoCo dataset

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Application of ZnO-nanoparticles to manage Rhizopus soft rot of sweet potato and prolong shelf-life

A reduction in crop spoilage and an increase in shelf-life is the goal of effective disease control methods. This study aimed to assess ZnO-nanoparticles (ZnO-NPs) as a safe, new protectant against Rhizopus soft rot of sweet potato. ZnO-NPs had a fungicidal effect against Rhizopus stolonifer when used at concentrations above 50 ppm. The results showed that tubers treated with ZnO-NPs exhibited fewer fungal populations (1.2 CFU per segment) than those that did not receive the treatment. Tubers infected with Rhizopus stolonifer and treated with ZnO-NPs showed no visible decay for up to 15 days, indicating that ZnO-NPs act as a coating layer on tuber surface. The greatest weight loss after 15 days of storage was reported in infected tubers (8.98%), followed by infected tubers treated with ZnO (6.54%) and infected tubers treated with ZnO-NPs (3.79%). The activity of cell-wall degrading enzymes, α-amylase and cellulase, were significantly increased in both infected tubers and those treated with ZnO, compared to the tubers treated with ZnO-NPs. These results confirm that coating with ZnO-NPs is an effective method of protecting sweet potato tubers from infection, maintaining their quality and increasing their shelf-life for up to 2 months in storage

Safety evaluation algorithm for signalized intersections in Abu Dhabi (UAE) using artificial intelligence

Vehicles traveling through signalized intersections in Abu Dhabi (UAE) experience high crash occurrence. An investigation was carried out to improve highway safety in Abu Dhabi. The research study identified the most significant factors contributing to the occurrence of road crashes at each intersection included in the study. Subsequently, this research provides a detailed signalized intersection safety evaluation algorithm. The algorithm utilizes expert opinions and employs artificial intelligence techniques to estimate a hazard index for signalized intersections. Using crash data, the algorithm is calibrated and the correlation between the algorithm results (hazard index) and crash rates in some selected signalized intersections is performed. The developed model and technique can be extended to be utilized in other regions and cities of similar environment and driving conditions

Development of phosphoryl-functionalized algal-PEI beads for the sorption of Nd(III) and Mo(VI) from aqueous solutions – Application for rare earth recovery from acid leachates

International audienceAlginate-PEI beads are functionalized by phosphorylation and applied for the sorption of Nd(III) and Mo(VI). The successful grafting of phosphoryl groups (as tributyl phosphate derivative) is characterized by FTIR and XPS analysis, elemental analysis, titration (pHPZC), TGA, BET and SEM-EDX analyses. The multi-functional characteristics of the sorbent (i.e., carboxylic, hydroxyl, amine and phosphate groups) contribute in the binding of metal ions having different physicochemical behaviors. The sorption of Nd(III) is strongly increased by phosphorylation, while for Mo(VI) the enhancement is rather limited. Optimum sorption occurs at pH 3–4: maximum sorption capacity reaches up to 1.46 mmol Nd(III) g−1 and 2.09 mmol Mo(VI) g−1; sorption isotherms are fitted by the Langmuir equation. The equilibrium is reached within 30–40 min and the kinetic profiles are simulated by the pseudo-first order rate equation. The coefficients of the effective diffusivity are close to the self-diffusivity of Nd(III) and Mo(VI) in water; as a confirmation of the limited impact of resistance to intraparticle diffusion in the kinetic control. The sorbent is selective for Nd(III) over Mo(VI) and other alkali-earth or base metals (at pH close to 2.5–3). Metals can be readily desorbed using 0.2 M HCl/0.5 M CaCl2 as the eluent. The loss in sorption does not exceed 5% at the fifth cycle, while desorption remains complete. A series of treatments (including acidic leachate, cementation, precipitation, sorption and elution) is successfully applied for the recovery of rare earths from Egyptian ore; with enrichment in the oxalate precipitate of Nd(III), Gd(III), Sm(III) and Eu(III)