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The effects of an increase in output power owing to the close arrangement of vertical-axis wind turbines (VAWTs) are well known. With the ultimate goal of determining the optimal layout of a wind farm (WF) for VAWTs, this study proposes a new method for quickly calculating the flow field and power output of a virtual WF consisting of two-dimensional (2-D) miniature VAWT rotors. This new method constructs a flow field in a WF by superposing 2-D velocity numerical data around an isolated single VAWT obtained through a computational fluid dynamics (CFD) analysis. In the calculation process, the VAWTs were gradually increased one by one from the upstream side, and a calculation subroutine, in which the virtual upstream wind speed at each VAWT position was recalculated with the effects of other VAWTs, was repeated three times for each arrangement with a temporal number of VAWTs. This method includes the effects of the velocity gradient, secondary flow, and wake shift as models of turbine-to-turbine interaction. To verify the accuracy of the method, the VAWT rotor power outputs predicted by the proposed method for several types of rotor pairs, four-rotor tandem, and parallel arrangements were compared with the results of previous CFD analyses. This method was applied to four virtual WFs consisting of 16 miniature VAWTs. It was found that a layout consisting of two linear arrays of eight closely spaced VAWTs with wide spacing between the arrays yielded a significantly higher output than the other three layouts. The high-performance layout had fewer rotors in the wakes of the other rotors, and the induced flow speeds generated by the closely spaced VAWTs probably mutually enhanced their output power.

The Arctic climate system is in great distress, warming faster than the rest of the world and transforming more rapidly than previously anticipated. Sustained and harmonized multidisciplinary observations at key locations are needed to fill knowledge gaps and evaluate the ongoing climate change impacts on the complex Arctic marine system. For more than a decade, the Distributed Biological Observatory (DBO) has functioned as a “detection array” for ecosystem changes and trends in the Pacific sector of the Arctic Ocean. This long-term collaborative initiative builds on active involvement of scientists conducting in situ observations within marine disciplines to systematically document how the arctic marine ecosystem is transforming with environmental change. The DBO concept is currently being expanded into other sectors of the Arctic, including Davis Strait and Baffin Bay, the Atlantic Arctic gateway area, and the East Siberian Sea. Through increased collaboration and joint practices, findings from these regional areas can leverage to pan-Arctic perspectives and improve our understanding of the entire Arctic Ocean. Common practices are now being developed, including key phenomena and relevant indicators to study. Also, we strive towards harmonized routines for sampling, analysis and data sharing to increase the comparability across both disciplines and regions, and to improve the usability of our in-situ observations also for the modelling and remote sensing scopes. An ambition is, moreover, to expand from today's predominantly open-sea coverage towards coastal regions, to the benefit of both local communities and researchers. The process of establishing a pan-Arctic DBO network is to a large part facilitated by the EU Horizon project Arctic PASSION (2022-2025). Here, we present the latest developments and shared priorities, as well as our vision of how to incorporate our efforts into other parallel processes aiming to strengthen the pan-Arctic observing system towards, during and beyond the upcoming IPY.

Seawater intrusion into soils caused by global climate change and tsunami disasters is a significant factor contributing to soil salinization in coastal vegetation areas, posing a critical threat to agriculture and food security. This study aimed to evaluate the seawater tolerance of Vigna marina, a wild Vigna species, through comparative laboratory experiments with Vigna radiata (mung bean) and Vigna angularis (adzuki bean). Unlike V. radiata and V. angularis, the seeds of V. marina exhibited significant buoyancy in seawater, remaining afloat for at least 30 days. After this prolonged seawater incubation, V. marina seeds maintained a 100% germination rate, whereas V. radiata and V. angularis failed to germinate under the same conditions. The photosynthetic activity of V. marina seedlings, evaluated via the Fv/Fm parameter, remained stable even after seven days of seawater irrigation. In contrast, V. radiata and V. angularis perished under seawater irrigation. Furthermore, V. marina seedlings exhibited sustained growth under seawater irrigation, showing consistent increases in both fresh and dry weight. These findings confirm that V. marina possesses remarkable tolerance to seawater, a critical characteristic for cultivation in areas affected by seawater intrusion.

Luo Ji-Wang, Yaji Kentaro, Chen Li, et al. Data-driven multi-fidelity topology design of fin structures for latent heat thermal energy storage. Applied Energy 377, 124596 (2024); https://doi.org/10.1016/j.apenergy.2024.124596. ; This work develops a data-driven multi-fidelity topology design (MFTD) method for designing fins in a latent heat thermal energy storage tube. The high-fidelity simulation resolves the actual solid-liquid phase change process using the enthalpy method, while the low-fidelity topology optimization (TO) simply considers the natural convection with Darcy flow. The above MFTD method is integrated into the framework of evolutional algorithm, and the variational autoencoder is introduced to generate new offspring. Fins for accelerating the melting and solidification processes at different Grashof number (Gr) are designed. It is found that when the fin volume fraction is low, the melt designs exhibit strong heterogeneity due to the strong convection, while the solidification designs are almost isotropic. Along with the increase of the fin volume fraction, the fins are first getting longer, then having more branches or sub-branches and finally becoming thicker. The superiority of the present data-driven MFTD method to the gradient-based direct TO method for solving optimization problems with strong multimodality has been demonstrated in this work. Results find that compared with the designs from direct TO, the MFTD melt design can further reduce the melting time by at least 27 % and 20 % at Gr = 3.3 × 103 and Gr = 3.3 × 104 respectively, and the MFTD solidification design can further shorten the solidification time by at least 9 %.

Different agricultural practices can be beneficial in Miscanthus × giganteus (M × g) phytotechnology applied to post-military and post-mining lands. However, only limited research has focused on supportive treatments using biochar produced from M × g waste. Indeed, when M × g phytotechnology is applied to contaminated soil, the biochar produced through the pyrolysis of the obtained biomass is contaminated, raising concerns about its further application. The current study tested the use of biochar produced from M × g roots cultivated long-term in slightly contaminated soil in the M × g phytotechnology of Cu- or Zn-spiked soils which is important for finding the solution toward valorization of the contaminated biomass. Two biochar doses (1.67 and 5.00%) were evaluated with varying levels of Cu (200 to 416 mg kg-1) or Zn (202 to 580 mg kg-1) concentrations in the soils. This study revealed a beneficial influence of biochar on M × g development, specifically by increasing the plant height and aboveground biomass by up to 20.4 and 115%, respectively. However, the root dry weight increased by 31.8% only at the highest application rate of biochar. The option for valorization of the contaminated biochar in the next phytoremediation process applied to soil contaminated more than the biochar itself was tested. The finding showed the positive influence of biochar on the M × g phytoremediation metrics such as tolerance index, bioconcentration factor, translocation factor, and comprehensive bioconcentration index which ensured the perspective of the proposed approach in the implementation of post-remediation management practice.

Off-grid water pumping systems (OGWPS) have become an increasingly popular area of research in the search for sustainable energy solutions. This paper presents a finite element method (FEM)-based design and analysis of Brushless-DC (BLDC) and Switched Reluctance Motors (SRM) designed for low-power water pumping applications. Utilizing adaptive finite element analysis (FEA), both motors were designed with identical ratings and design parameters to ensure a fair comparison. The design geometries adhere to the NEMA 42 standard. An (n + 1) switch converter topology was implemented to energize SRM phases, while a Cuk converter coupled with a three-phase voltage source inverter (VSI) was used to power the BLDC motor. The study provides a comprehensive comparative analysis of the torque profiles of both motor types under identical operating conditions. The BLDC motor achieved a maximum torque of 11.5 Nm and an efficiency of 91.9%, while the SRM demonstrated a maximum torque of 3.8 Nm and an efficiency of 94.6%. The torque ripple of the BLDC motor was significantly lower (0.73 pu) compared to the SRM (1.19 pu), indicating smoother operation. Simulation results obtained using advanced computational electromagnetic tools highlight the performance efficiencies and potential advantages of each motor type for off-grid water pumping systems. This research investigates the viability of both BLDC and SRM technologies in enhancing the efficiency and reliability of OGWPS, with the BLDC motor showing superior performance in terms of torque and operational smoothness. The simulation results of converter topologies used for respective motors have been further validated using experimentation on respective prototype motors.

A novel functional material named “multifunctional composite magnet” has been created, which simultaneously exhibits record-high transverse thermoelectric generation performance and permanent magnet features.