Virtual Inertia Adaptive Control of a Doubly Fed Induction Generator (DFIG) Wind Power System with Hydrogen Energy Storage

This paper presents a doubly fed induction generator (DFIG) wind power system with hydrogen energy storage, with a focus on its virtual inertia adaptive control. Conventionally, a synchronous generator has a large inertia from its rotating rotor, and thus its kinetic energy can be used to damp out fluctuations from the grid. However, DFIGs do not provide such a mechanism as their rotor is disconnected with the power grid, owing to the use of back-to-back power converters between the two. In this paper, a hydrogen energy storage system is utilized to provide a virtual inertia so as to dampen the disturbances and support the grid’s stability. An analytical model is developed based on experimental data and test results show that: (1) the proposed method is effective in supporting the grid frequency; (2) the maximum power point tracking is achieved by implementing this proposed system; and, (3) the DFIG efficiency is improved. The developed system is technically viable and can be applied to medium and large wind power systems. The hydrogen energy storage is a clean and environmental-friendly technology, and can increase the renewable energy penetration in the power network

Silicon (Si) biochar for the mitigation of arsenic (As) bioaccumulation in spinach (Spinacia oleracean) and improvement in the plant growth

In many parts of the world, growing crops on polluted soils often leads to elevated levels of pollutants in plant tissues. Minimizing the transfer of these pollutants into edible plant tissues while improving plant growth and productivity is a major area of research. In this study, we investigated the efficiency of silicon-modified biochar in reducing the uptake of As(III) in spinach (Spinacia oleracean) while simultaneously increasing the plant biomass. Unmodified biochars (uBC) and silicon-modified biochars (SiBC) were prepared from bamboo at 300 and 600 °C and characterized by Scanning Electron Microscopy with Energy Dispersive X-ray (SEM EDX), Fourier Transform Infrared Spectrometry (FTIR), X-ray Photoelectron Spectrometry (XPS), and X-ray Diffraction analysis (XRD). The bioaccumulation of As(III) in the edible part of spinach significantly decreased by 33.8 and 37.7% following the amendment of, respectively, 2% and 5% SiBC in soil. Biochar amendment increased the concentration of As(III) in pore water by 64.4% as a result of increased soil pH from 6.83 ± 0.4 to 8.01 ± 0.1 and dissolved organic carbon (DOC) from 7.02 ± 3.7 to 22.58 ± 3.7 g kg−1. However, the uptake of As(III) into spinach was prevented by silicon, which was preferentially transported to the plant through the same transport pathway as As(III). Dry biomass yield in spinach also significantly increased by 67.7% and strongly correlated (R2 = 0.97) with CaCl2 extractable Si in the plant. The results highlighted the effectiveness of SiBC in reducing the toxic effects of As in the environment and overall dietary exposure to the pollutant. The slow release of Si from biochars (<48.42%) compared to soil (87.39%) also suggested that SiBC can be efficient sources of Si fertilization for annual crops which can significantly reduce the increasing demand for Si fertilizers and their sustainable use in the environment

VENUS: A Geometrical Representation for Quantum State Visualization

Visualizations have played a crucial role in helping quantum computing users explore quantum states in various quantum computing applications. Among them, Bloch Sphere is the widely-used visualization for showing quantum states, which leverages angles to represent quantum amplitudes. However, it cannot support the visualization of quantum entanglement and superposition, the two essential properties of quantum computing. To address this issue, we propose VENUS, a novel visualization for quantum state representation. By explicitly correlating 2D geometric shapes based on the math foundation of quantum computing characteristics, VENUS effectively represents quantum amplitudes of both the single qubit and two qubits for quantum entanglement. Also, we use multiple coordinated semicircles to naturally encode probability distribution, making the quantum superposition intuitive to analyze. We conducted two well-designed case studies and an in-depth expert interview to evaluate the usefulness and effectiveness of VENUS. The result shows that VENUS can effectively facilitate the exploration of quantum states for the single qubit and two qubits

Hepatitis B virus infection and replication in a new cell culture system established by fusing HepG2 cells with primary human hepatocytes

BackgroundHepatitis B virus (HBV) infection is strictly species and tissue specific, therefore none of the cell models established previously can reproduce the natural infection process of HBV in vitro. The aim of this study was to establish a new cell line that is susceptible to HBV and can support the replication of HBV.MethodsA hybrid cell line was established by fusing primary human hepatocytes with HepG2 cells. The hybrid cells were incubated with HBV-positive serum for 12 hours. HBV DNA was detected by quantitative fluorescence polymerase chain reaction (QF-PCR). HBsAg (surface antigen) and HBeAg (extracellular form of core antigen) were observed by electrochemiluminescence (ECL). HBcAg (core antigen) was detected by the indirect immunofluorescence technique. HBV covalently closed circular DNA (cccDNA) was analyzed by Southern blot hybridization and quantified using real-time PCR.ResultsA new cell line was established and named HepCHLine-7. The extracellular HBV DNA was observed from Day 2 and the levels ranged from 9.80 (± 0.32) × 102 copies/mL to 3.12 (± 0.03) × 104 copies/mL. Intracellular HBV DNA was detected at Day 2 after infection and the levels ranged from 7.92 (± 1.08) × 103 copies/mL to 5.63 (± 0.11) × 105 copies/mL. HBsAg in the culture medium was detected from Day 4 to Day 20. HBeAg secretion was positive from Day 5 to Day 20. HBcAg constantly showed positive signals in approximately 20% (± 0.82%) of hybrid cells. Intracellular HBV cccDNA could be detected as early as 2 days postinfection and the highest level was 15.76 (± 0.26) copies/cell.ConclusionHepCHLine-7 cells were susceptible to HBV and supported the replication of HBV. They are therefore suitable for studying the complete life cycle of HBV

Silicon (Si) biochar for the mitigation of arsenic (As) bioaccumulation in spinach (Spinacia oleracean) and improvement in the plant growth

In many parts of the world, growing crops on polluted soils often leads to elevated levels of pollutants in plant tissues. Minimizing the transfer of these pollutants into edible plant tissues while improving plant growth and productivity is a major area of research. In this study, we investigated the efficiency of silicon-modified biochar in reducing the uptake of As(III) in spinach (Spinacia oleracean) while simultaneously increasing the plant biomass. Unmodified biochars (uBC) and silicon-modified biochars (SiBC) were prepared from bamboo at 300 and 600 °C and characterized by Scanning Electron Microscopy with Energy Dispersive X-ray (SEM EDX), Fourier Transform Infrared Spectrometry (FTIR), X-ray Photoelectron Spectrometry (XPS), and X-ray Diffraction analysis (XRD). The bioaccumulation of As(III) in the edible part of spinach significantly decreased by 33.8 and 37.7% following the amendment of, respectively, 2% and 5% SiBC in soil. Biochar amendment increased the concentration of As(III) in pore water by 64.4% as a result of increased soil pH from 6.83 ± 0.4 to 8.01 ± 0.1 and dissolved organic carbon (DOC) from 7.02 ± 3.7 to 22.58 ± 3.7 g kg−1. However, the uptake of As(III) into spinach was prevented by silicon, which was preferentially transported to the plant through the same transport pathway as As(III). Dry biomass yield in spinach also significantly increased by 67.7% and strongly correlated (R2 = 0.97) with CaCl2 extractable Si in the plant. The results highlighted the effectiveness of SiBC in reducing the toxic effects of As in the environment and overall dietary exposure to the pollutant. The slow release of Si from biochars (<48.42%) compared to soil (87.39%) also suggested that SiBC can be efficient sources of Si fertilization for annual crops which can significantly reduce the increasing demand for Si fertilizers and their sustainable use in the environment