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In this Article we analyze whether and how the legal reactions to COVID-19 brought permanent changes to three main areas that are at the very basis of the study of comparative constitutional law: the horizontal separation of powers in different forms of government; the vertical separation of powers and its effects on forms of state; and the reviewability of limitations to human rights and personal freedoms by bodies exercising constitutional review. Rather than just examining and categorizing the reactions, we search for the political, institutional, factual, and sometimes even cultural rationales at the basis of each trend. Our claim is that COVID-19 was a driving force for relevant changes in the three analyzed areas, but we also recognize that these changes did not come “out of the blue,” as they were already “latent” in considered legal systems. The analysis demonstrates that the traditional categories we use to classify the forms of government, forms of state, and the mechanisms of constitutional review, although being useful paradigms to study these topics, have in themselves the potential to be “stretched,” and even unhinged, when global and long-lasting emergencies, as COVID-19, are in place.

The relations between the EU institutions established by the Treaty of Lisbon, as well as the relations between EU competences and the constitutional sovereignty of the member states, call for constant examination. Through the inductive method of constitutional law, we arrive at the assessment of the European Union as a special composite two-level power. Thus, we use model induction of “form of state”, “form of government” and analysis of types of lawsuits before the Court of Justice of the EU. The internal organization of the EU established in the treaties, as well as the actual decision-making, are dominated by EU bodies of an executive nature. Their executive activity then deepened in several crisis situations, such as the permanent threat of terrorism, the ongoing immigration onslaught on EU territory, the recent COVID epidemic, and the current ongoing aggression of the Russian Federation against Ukraine. The methodology of constitutional law thus reaches the conclusion about the necessity of the positive development of the EU system by improving both horizontal control relations within the EU institutional framework itself, as well as control measures of a procedural nature, especially in relation to derived EU law and possibly also against other interventions (steps) by EU bodies.

Incipient wave breaking on a vertical circular pile is simulated with a Reynolds stress–$\\omega$ turbulence model. Comparison of results simulated with a stabilized two-equation turbulence model, as well as no turbulence model, demonstrates that the breaking point and the peak force on a vertical cylinder due to incipient breaking should not be affected by the turbulence closure model, provided that it is stable and the simulations are converged. Notably, the present results show that the build-up to peak force induced by incipient wave breaking can be accurately predicted without any turbulence closure model. However, for the prediction of the secondary load cycle (SLC), proper turbulence modelling is required, as this process involves both turbulence production and lee-side flow separation. The Reynolds stress–$\\omega$ model is demonstrated to predict the SLC more accurately than a stabilized two-equation $k$–$\\omega$ turbulence model, as the flow separation points and vorticity field are better predicted. Some existing studies indicate that the generation of the SLC does not necessarily result from flow separation, but is rather due to the suction force. The present work finds that the occurrence and point of flow separation significantly affect the magnitude of the suction force, which hence affects the SLC prediction significantly. For waves breaking on a vertical pile, proper turbulence modelling is therefore essential for accurate SLC predictions. (In the above, $k$ is the turbulent kinetic energy density and $\\omega$ is the specific dissipation rate.)

Triboelectric nanogenerator (TENG) has made significant progress in wind energy harvesting. As the most advantageous rotary TENG among wind energy harvesters, the severe material wear and the output that fluctuates with wind speed seriously hinder the application of TENG wind energy harvesters. In this study, we propose a round-trip oscillation triboelectric nanogenerator (RTO-TENG) consisting of a crank transmission mechanism and a power generation unit. The RTO-TENG utilizes a simple crank transmission mechanism combined with a zigzag-laminated triboelectric nanogenerator (Z-TENG) to achieve high-performance constant output and low material wear. The crank transmission mechanism can realize the transformation from circular motion to arc reciprocating motion, converting the random wind energy into bi-directional kinetic energy, driving the vertical contact and separation of the Z-TENG. Due to the low transmission ratio (1:1) of the crank transmission mechanism and the consistent frequency of the Z-TENG contact–separation with that of the pendulum, the RTO-TENG’s power generation unit (10 Z-TENGs) is insensitive to changes in wind speed, resulting in a constant and stable output response at various speeds. After 480,000 cycles, the output of RTO-TENG decreased by only 0.9% compared to the initial value of 6 µC, and the scanning electron microscopy (SEM) images of the polytetrafluoroethylene (PTFE) film showed no significant wear on the surface of the friction layer, demonstrating excellent output stability and abrasion resistance of the RTO-TENG wind energy collector’s material. The equipped energy management module, based on a gas discharge tube switch, can further enhance the output performance of the RTO-TENG. After optimizing its inductor parameter L to match the load capacitor, it can charge a 220 µF load capacitor to 13.4 V in 40 s, resulting in a 298% improvement in charging speed compared to the voltage of 4.48 V without the management module. Therefore, the RTO-TENG can efficiently provide power to low-power small electronic devices for Internet of Things (IoTs), such as road traffic warning signs and thermo-hygrometers.

The tuning of vertical morphology is critical and challenging for organic solar cells (OSCs). In this work, a high open‐circuit voltage (VOC) binary D18‐Cl/L8‐BO system is attained while maintaining the high short‐circuit current (JSC) and fill factor (FF) by employing 1,4‐diiodobenzene (DIB), a volatile solid additive. It is suggested that DIB can act as a linker between donor or/and acceptor molecules, which significantly modifies the active layer morphology. The overall crystalline packing of the donor and acceptor is enhanced, and the vertical domain sizes of phase separation are significantly decreased. All these morphological changes contribute to exciton dissociation, charge transport, and collection. Therefore, the best‐performing device exhibits an efficiency of 18.7% with a VOC of 0.922 V, a JSC of 26.6 mA cm−2, and an FF of 75.6%. As far as it is known, the VOC achieved here is by far the highest among the reported OSCs with efficiencies over 17%. This work demonstrates the high competence of solid additives with two iodine atoms to tune the morphology, particularly in the vertical direction, which can become a promising direction for future optimization of OSCs. The solid additive, 1,4‐diiodobenzene (DIB), has a high competence to optimize the vertical morphology of bulk heterojunction active layer, resulting in a high efficiency of 18.7% with a open‐circuit voltage (VOC) of 0.922 V, a short‐circuit current (JSC) of 26.6 mA cm−2, and a fill factor (FF) of 75.6% for DIB‐processed D18‐Cl/L8‐BO binary devices.

This article reports the effectiveness of triboelectric energy harvesting using human motion by employing synchronous switch harvesting on inductors. The triboelectric nanogenerator (TENG) consists of an assembly of films of polytetraflouroethylene, nylon, copper, and aluminum, which produces and collects the charge during vertical motion. In order to improve and compare the electrical performance, the power generated through TENG was tested using a standard interface and series and parallel synchronized switch harvesting on inductor (SSHI) circuits. Our experimental results revealed that the series-SSHI circuit can significantly increase the amount of power extracted from triboelectric materials during walking. A peak DC output voltage of 32.78 V across 1 μF capacitance and 25 MΩ resistance and maximum power of 55.88 μW across a 10 MΩ resistance were achieved using a series-SSHI circuit. These results are significantly higher than those of a non-switched standard circuit without the use of inductors. We conclude that the continuous DC output obtained from human biomechanical energy at low frequency (6.5 Hz) can act as a reliable source for the sustainable operation of low power electronics.

Slotted airfoils mitigate the flow separation on the blades operating at high angles of attack in the upwind region, consequently augmenting the power coefficient and reducing the startup wind speed of Darrieus vertical axis wind turbines (VAWTs). Nonetheless, the presence of the slot structure alters the original flow dynamics, inducing flow separation when the blade operates in the downwind region and at elevated blade tip speed ratios (TSR), which leads to a reduction in the blade’s power coefficient. This study establishes an aerodynamic model of the flow field migration around the blade surface by utilizing the lattice Boltzmann method in conjunction with large eddy simulation to ascertain the influence of the inlet and outlet positions of the slot on the flow field structure across different wind regions. The simulations indicate that, under the downwind region and at high TSR, positioning the slot at the midsection of the blade, although it expands flow separation near the trailing-edge, does not disrupt the primary flow at the leading-edge. Unexpectedly, the slot optimizes the pressure distribution on the pressure side of the blade, thereby enhancing the blade’s performance in the downwind region. At a TSR of 3.3, the average power coefficient of the blades in the downwind region increases by up to 63.62%. These results offer valuable insights for the implementation of slotted airfoils to enhance energy conversion efficiency in VAWTs’ design optimization.

This study provides a numerical investigation about J‐shaped straight‐bladed Darrieus vertical axis wind turbines equipped with outboard, inboard, and two‐sided Gurney flap (GF). The performance of the turbines is examined for different GF heights and tip speed ratios (TSRs). The aerodynamic analysis is carried out using power curves, vorticity field, and pressure field surrounding the wind turbine. The results indicate that employing the inboard GF effectively enhances the turbine’s performance by harnessing the drag force in the desired direction and postponing the flow separation up to 14° of azimuth angle. The inboard GF with a height of 0.75% chord length exhibits the best performance among the GFs, showing an increase in output power at higher TSRs up to 12.35%. Conversely, the use of outboard and two‐sided GFs of any height cannot improve the turbine efficiency.

High-fidelity two-dimensional unsteady Reynolds-averaged Navier-Stokes (URANS) simulations are employed to investigate the influence of boundary layer suction through a slot located near the leading edge of a vertical axis wind turbine operating in dynamic stall. The analysis includes both steady and unsteady suction with different frequencies. The results shows that: (i) when the suction slot is located within the chordwise extent of the laminar separation bubble, dynamic stall can be avoided with minimal suction amplitude; (ii) the most promising suction location is the most upstream suction location studied, at 8.5%c where c is the blade chord length; (iii) the suction only needs to be applied during the azimuthal angles when dynamic stall occurs; (iv) the oscillation frequency of the suction velocity has insignificant influence on the obtained turbine power gain; (v) applying unsteady suction is interesting as it reduces the energy consumption of the suction system, thus the net power gain.

Vertical axis wind turbine (VAWT) faces aerodynamic efficiency challenges due to dynamic stall and flow separation. This study investigates the combined optimization of a toward-outside dimple-Gurney flap (TO-DGF) and pitch angle to enhance the aerodynamic performance of a NACA0021 three-blade VAWT. We analyzed aerodynamic performance and flow field structures under varying pitch angles using large eddy simulations based on the lattice Boltzmann method. The baseline VAWT and TO-DGF VAWT achieve optimal performance at pitch angles of β = +8° and β = +6°, respectively, improving efficiency by 5.35% and 4.56% compared to β = 0°. TO-DGF induces Kármán vortex shedding to guide suction surface flow, while pitch angle adjustment optimizes the angle of attack, delaying dynamic stall. At a tip speed ratio of 2.4, the optimized TO-DGF VAWT increases wind energy utilization by up to 7.78%.