Stability analysis of VSC-HVDC system based on new phase-locked-loop less voltage oriented control method

Voltage Source Converters-based High Voltage Direct Current (VSC-HVDC) systems are generally implemented to transmit power across long distances due to their low cost and flexibility. This paper will discuss a new simple and low-computational-burden phase-locked loop less voltage-oriented control strategy (PLL-less-VOC strategy) for controlling and synchronizing a VSC-HVDC system in a synchronous rotating frame (dq frame). The proposed method is used not only to control the VSC-HVDC but also to obtain the mathematical model of both VSCs-based HVDC systems in the dq frame using the basics of the direct instantaneous power control theory (DPC) without using PLL and Park transformations. The proposed PLL-less-VOC strategy is equivalent to the conventional VOC strategy for steady-state stability, but it has the benefit of both conventional VOC and DPC, better transient stability performance, and low computational burden in the implementation. The experimental tests using STM32F407G microcontroller demonstrate that the proposed control strategy has better dynamic stability under certain exceptional conditions such as step changes on DC-link voltage change, powers change, and three-phase fault

Automatic data featurization for enhanced proactive service auto-scaling: Boosting forecasting accuracy and mitigating oscillation

Edge computing has gained widespread adoption for time-sensitive applications by offloading a portion of IoT system workloads from the cloud to edge nodes. However, the limited resources of IoT edge devices hinder service deployment, making auto-scaling crucial for improving resource utilization in response to dynamic workloads. Recent solutions aim to make auto-scaling proactive by predicting future workloads and overcoming the limitations of reactive approaches. These proactive solutions often rely on time-series data analysis and machine learning techniques, especially Long Short-Term Memory (LSTM), thanks to its accuracy and prediction speed. However, existing auto-scaling solutions often suffer from oscillation issues, even when using a cooling-down strategy. Consequently, the efficiency of proactive auto-scaling depends on the prediction model accuracy and the degree of oscillation in the scaling actions.This paper proposes a novel approach to improve prediction accuracy and deal with oscillation issues. Our approach involves an automatic featurization phase that extracts features from time-series workload data, improving the prediction’s accuracy. These extracted features also serve as a grid for controlling oscillation in generated scaling actions. Our experimental results demonstrate the effectiveness of our approach in improving prediction accuracy, mitigating oscillation phenomena, and enhancing the overall auto-scaling performance

Effect of pH Value on the Bandgap Energy and Particles Size for Biosynthesis of ZnO Nanoparticles: Efficiency for Photocatalytic Adsorption of Methyl Orange

In this paper, ZnO nanoparticles (NPs) were greenly synthesized at different pH values of 4, 6, 9.5, and 11 via Portulaca oleracea leaf extract, and the effect of pH on the optical and structural properties was studied. UV-Vis spectrophotometers and FTIR spectroscopy characterized the optical properties. Meanwhile, the structural properties were characterized via Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). Furthermore, their photocatalytic dye degradation was examined against methyl orange dye. The characterization results have confirmed the successful biosynthesis of ZnO nanoparticles with a size ranging between 22.17 to 27.38 nm. The synthesis pH value significantly influenced ZnO NPs’ optical and morphological properties. The results have also indicated the high performance of the greenly synthesized ZnO NPs for dye degradation

The plant-growth-promoting actinobacteria of the genus Nocardia induces root nodule formation in Casuarina glauca

Actinorhizal plants form a symbiotic association with the nitrogen-fixing actinobacteria Frankia. These plants have important economic and ecological benefits including land reclamation, soil stabilization, and reforestation. Recently, many non-Frankia actinobacteria have been isolated from actinorhizal root nodules suggesting that they might contribute to nodulation. Two Nocardia strains, BMG51109 and BMG111209, were isolated from Casuarina glauca nodules, and they induced root nodule-like structures in original host plant promoting seedling growth. The formed root nodule-like structures lacked a nodular root at the apex, were not capable of reducing nitrogen and had their cortical cells occupied with rod-shaped Nocardiae cells. Both Nocardia strains induced root hair deformation on the host plant. BMG111209 strain induced the expression of the ProCgNin:Gus gene, a plant gene involved in the early steps of the infection process and nodulation development. Nocardia strain BMG51109 produced three types of auxins (Indole-3-acetic acid [IAA], Indole-3-Byturic Acid [IBA] and Phenyl Acetic Acid [PAA]), while Nocardia BMG111209 only produced IAA. Analysis of the Nocardia genomes identified several important predicted biosynthetic gene clusters for plant phytohormones, secondary metabolites, and novel natural products. Co-infection studies showed that Nocardia strain BMG51109 plays a role as a helper bacteria promoting an earlier onset of nodulation. This study raises many questions on the ecological significance and functionality of Nocardia bacteria in actinorhizal symbioses

The plant-growth-promoting actinobacteria of the genus <em>Nocardia</em> induces root nodule formation in <em>Casuarina glauca</em>

International audienceActinorhizal plants form a symbiotic association with the nitrogen-fixing actinobacteria Frankia. These plants have important economic and ecological benefits including land reclamation, soil stabilization, and reforestation. Recently, many non-Frankia actinobacteria have been isolated from actinorhizal root nodules suggesting that they might contribute to nodulation. Two Nocardia strains, BMG51109 and BMG111209, were isolated from Casuarina glauca nodules, and they induced root nodule-like structures in original host plant promoting seedling growth. The formed root nodule-like structures lacked a nodular root at the apex, were not capable of reducing nitrogen and had their cortical cells occupied with rod-shaped Nocardiae cells. Both Nocardia strains induced root hair deformation on the host plant. BMG111209 strain induced the expression of the ProCgNin:Gus gene, a plant gene involved in the early steps of the infection process and nodulation development. Nocardia strain BMG51109 produced three types of auxins (Indole-3-acetic acid [IAA], Indole-3-Byturic Acid [IBA] and Phenyl Acetic Acid [PAA]), while Nocardia BMG111209 only produced IAA. Analysis of the Nocardia genomes identified several important predicted biosynthetic gene clusters for plant phytohormones, secondary metabolites, and novel natural products. Co-infection studies showed that Nocardia strain BMG51109 plays a role as a helper bacteria promoting an earlier onset of nodulation. This study raises many questions on the ecological significance and functionality of Nocardia bacteria in actinorhizal symbioses