Wind Disturbances Research Articles

Effect of solar wind disturbances on small-amplitude simultaneous Forbush events during solar cycle 23

The transient and rapid reduction in galactic cosmic ray (GCR) flux intensity, commonly referred to as Forbush decrease (FD), is widely used as a mediator variable in searching for solar-terrestrial weather linkages. Whereas literature in the field is replete with high-amplitude (FD(%) ⩾3) FD-based analyses, the empirical connections between low-amplitude (FD(%) ⩽3) events and Sun-Earth variables are seldom tested. It is recently observed that the dearth of such studies might be due to the daunting task of accurate detection/precise timing of FDs and other transient astrophysical events. Using a sensitive version of the FD detection algorithm, we selected 264, 267, and 206 low amplitude (FD(%) ⩽3) FDs from the daily GCR data of Hermanus (HRMS), Newark (NWRK) and Oulu (OULU) neutron monitor stations respectively during solar cycle 23. A total of 80 simultaneous small-amplitude FDs were identified from the three stations with a simple coincident computer code. Statistically significant correlations at 95% confidence level exist between the planetary K-index (Kp), disturbance storm time index (Dst), planetary A-index (Ap), and the corresponding simultaneous small-amplitude FDs at OULU station, but not found in HRMS and NWRK data. These significant links between the weak FDs and the geomagnetic indices (Kp, Dst, and Ap) at OULU station suggest that the parameters (Kp, Dst, and Ap) are likely connected with some common solar activities.

Geographic variation in resistance of Scots pine (Pinus sylvestris L.) to wind loading across different wind environments in Europe

The harmful impacts of wind disturbances are expected to increase in European forests more under relatively mild wind environments (e.g. North-East Europe) compared to harsh wind conditions (e.g. British Isles). They are also expected to increase particularly under loose soil conditions (e.g. organic soils). However, harmful impacts of wind disturbances may be mitigated by such adaptive management, which improves the mechanical stability of trees. Populations of widespread tree species, such as Scots pine (Pinus sylvestris L.), are highly plastic in terms of morphology and ecology, resulting in geographic variation of the traits crucial also for tree mechanical stability. The aim of this study was to assess the regional differences in the resistance of Scots pine to wind loading between populations along the European West-East gradient of wind environments. Furthermore, the local differences between neighbouring stands on freely draining mineral and drained deep peat soils in Latvia were assessed. The loading resistance of Scots pine was consistent among the studied populations across the gradient of European wind environments, suggesting regional variation in adjustment of traits crucial for tree mechanical stability. Whereas Scots pines growing in neighbouring stands on freely draining mineral and drained deep peat exhibited differences in loading resistance, suggesting specific local acclimations. However, to account for genetic control over traits crucial for tree mechanical stability, loading resistance of Scots pine populations needs to be assessed in common gardens.

Effect of High-Voltage Electrostatic Precipitator Dust Collection Plate Structure on Collection Efficiency.

To investigate the effect of changes in the dust collector structure on the flow field and electric field distribution resulting from the secondary flow generated by the corona discharge in the collector coupled with the main flow and to improve the dust collection efficiency of the ESP, a folding plate design has been adopted. A multiphysics-coupled corona discharge and flow field numerical model was analyzed to analyze the internal flow and electric field characteristics of linear flat plates and folded plates with three different pole configurations. The study indicates that the dust collecting plate's structure significantly affects the dust collector's internal flow field and electric field distribution within the dust collector. The near-plate electric field and flow field inside the folded plate type are superior to those of the linear flat electrostatic precipitator. With the augmentation of the inlet velocity, the ionic wind disturbance on the flow field inside the electrostatic precipitator channel gradually decreases. Additionally, the folding plate has a certain inhibitory effect on the influence of the ionic wind. At an inlet velocity of 0.5 m/s, the speed near the folding plate is approximately 20% lower than that of the traditional linear flat plate. The folding plate can effectively reduce the flow velocity near the dust collection plate, thereby reducing the occurrence of particle re-entrainment and improving dust removal efficiency. By comparing the speed at the center line of the plate and near the plate, it is obvious that the speed of model B decreases significantly, and as the number of discharge electrodes increases, the speed decreases more obviously. At the same time, when the dust collection efficiency of the two models was compared, it was found that the working efficiency of the B model has been significantly improved, among which the B3 model has the best dust collection effect.

Adaptive sliding mode control for quadrotor transport systems with uncertain parameters and disturbances

SummaryQuadrotor transportation systems have been widely utilized in both commercial and civilian fields. However, challenges arise due to the variable payload mass and unpredictable wind disturbances during cargo transport, potentially leading to excessive payload swinging and system instability. To tackle this issue, this article proposes an adaptive sliding mode control approach that concurrently achieves trajectory tracking for the quadrotor and mitigates payload swinging. In the outer loop subsystem, the quadrotor dynamics model is partitioned into two components that is, actuated and underactuated components. Sliding surfaces are designed based on this divided system model, and two adaptive laws are designed to compensate for payload mass uncertainty and unknown wind disturbances. The system's asymptotic stability is assured through the application of the Lyapunov theorem. In the inner loop subsystem, a disturbance rejection controller is formulated. Comparative simulation results conclusively demonstrate the outstanding performance of the proposed method in terms of trajectory tracking and robustness.

Reinforcement Learning-Based Energy-Saving Path Planning for UAVs in Turbulent Wind

The unmanned aerial vehicle (UAV) is prevalent in power inspection. However, due to a limited battery life, turbulent wind, and its motion, it brings some challenges. To address these problems, a reinforcement learning-based energy-saving path-planning algorithm (ESPP-RL) in a turbulent wind environment is proposed. The algorithm dynamically adjusts flight strategies for UAVs based on reinforcement learning to find the most energy-saving flight paths. Thus, the UAV can navigate and overcome real-world constraints in order to save energy. Firstly, an observation processing module is designed to combine battery energy consumption prediction with multi-target path planning. Then, the multi-target path-planning problem is decomposed into iterative, dynamically optimized single-target subproblems, which aim to derive the optimal discrete path solution for energy consumption prediction. Additionally, an adaptive path-planning reward function based on reinforcement learning is designed. Finally, a simulation scenario for a quadcopter UAV is set up in a 3-D turbulent wind environment. Several simulations show that the proposed algorithm can effectively resist the disturbance of turbulent wind and improve convergence.

Some Features of Interacting Solar Wind Disturbances

Some Features of Interacting Solar Wind Disturbances

Fault-Tolerant Control for Multi-Quadcopter with Suspended Payload under Wind Disturbance

Delivering payload with multiple quadcopters necessitates a reliable backup system. This research introduces a fault-tolerant design specifically for multi-drone payload transportation. The system employs formation control, ensuring the weight is evenly distributed among all functioning drones. This research tackles the challenge of reliable payload delivery with multi-drone systems. It proposes a new fault-tolerant control system specifically designed for this purpose. The system addresses a limitation in existing solutions by incorporating a simple PD controller alongside a fault-tolerant strategy. This approach allows the system to maintain operation even if a drone malfunctions. The paper further demonstrates the system's effectiveness through simulations. Results show the system's ability to maintain stability with minimal altitude loss (only 6.3cm) and rapid position reconfiguration (within 3.96 seconds) even under windy conditions. These findings highlight the potential of this fault-tolerant design to significantly improve multi-drone payload delivery, especially for missions requiring high levels of stability and redundancy.

Controlling a Quadcopter with Static Loads and Dynamic Wind Disturbances using a Fuzzy Inference System

Maneuverability, hover, and simple mechanical design are the advantages of quadcopters. However, because quadcopters are smaller and lighter, they are more susceptible to wind than manned aircraft. The winds that cause air accidents are divided into several categories, namely downburst, turbulent wind, wind shear, and wind vortices. Disturbances and uncertainties, such as wind gusts, can result in difficulties in executing a mission on an accurate flight path. Quadcopter resilience is an important topic for UAV. Especially if the quadcopter is in terrain that is difficult for humans to reach. Hence, the system is susceptible and experiences reduced stability. Controlling a quadcopter with a cube-shaped static load to withstand turbulent wind gusts in this research uses robust Fuzzy Inference System control and trajectory control using LQR with Command-Generator Tracking. The results achieved through fuzzy control can fortify the quadcopter against half of the overall turbulent wind gusts with an RMSE of 0.0546. In contrast with the LQR-CGT control, which still exhibits an RMSE of 0.0795.

Salvage logging and subsequent post‐windthrow management diminish forest bird communities for two decades

Abstract Post‐disturbance forest management is known to impair biodiversity, including bird communities, but most studies focus on short‐term effects of salvage logging, without recognition of the cumulative, lasting impact of collective post‐disturbance silvicultural practices. We tracked bird community succession in a temperate pine forest from 5 to 19 years after wind disturbance in managed and unmanaged windthrow areas, covering the period from gap creation to early canopy regeneration and comparing it to nearby production forest unaffected by wind disturbance. Bird communities of unmanaged windthrow were consistently the richest in terms of bird abundance and richness. They hosted comparable forest bird diversity to unaffected production stands throughout the study period, as well as a substantial diversity of farmland birds. Managed and unmanaged windthrows followed two distinct successional pathways and did not converge. Despite the bird communities in both windthrows gradually resembling those found in undisturbed forests as the canopy regenerated, each type of windthrow and the unaffected production forest maintained distinct communities until the end of the study. Synthesis and applications. Restraining from any active post‐windthrow management sets bird succession on a distinct pathway, leading to unique and diverse bird communities. We advocate viewing natural disturbances as cost‐effective ecosystem restoration tools, provided no active management is implemented. Furthermore, we advise against using the term ‘salvage logging’ to refer to collective post‐disturbance silvicultural practices, as its varying interpretation may lead to growing confusion as the number of long‐term studies increase.

Tracking shifts in forest structural complexity through space and time in human‐modified tropical landscapes

Habitat structural complexity is an emergent property of ecosystems that directly shapes their biodiversity, functioning and resilience to disturbance. Yet despite its importance, we continue to lack consensus on how best to define structural complexity, nor do we have a generalised approach to measure habitat complexity across ecosystems. To bridge this gap, here we adapt a geometric framework developed to quantify the surface complexity of coral reefs and apply it to the canopies of tropical rainforests. Using high‐resolution, repeat‐acquisition airborne laser scanning data collected over 450 km2 of human‐modified tropical landscapes in Borneo, we generated 3D canopy height models of forests at varying stages of recovery from logging. We then tested whether the geometric framework of habitat complexity – which characterises 3D surfaces according to their height range, rugosity and fractal dimension – was able to detect how both human and natural disturbances drive variation in canopy structure through space and time across these landscapes. We found that together, these three metrics of surface complexity captured major differences in canopy 3D structure between highly degraded, selectively logged and old‐growth forests. Moreover, the three metrics were able to track distinct temporal patterns of structural recovery following logging and wind disturbance. However, in the process we also uncovered several important conceptual and methodological limitations with the geometric framework of habitat complexity. We found that fractal dimension was highly sensitive to small variations in data inputs and was ecologically counteractive (e.g. higher fractal dimension in oil palm plantations than old‐growth forests), while rugosity and height range were tightly correlated (r = 0.75) due to their strong dependency on maximum tree height. Our results suggest that forest structural complexity cannot be summarised using these three descriptors alone, as they overlook key features of canopy vertical and horizontal structure that arise from the way trees fill 3D space.Keywords: Forest disturbance, LiDAR, logging, recovery, remote sensing, structural complexity

Adaptive control of quadrotor suspended load systems with variable payload and wind disturbances

AbstractThis paper introduces an adaptive control scheme for quadrotor suspended load systems, to track desired trajectory with variable payload and wind disturbances. The dynamic model of the quadrotor suspended load system is developed, taking into account the impact of the wind field described by the Dryden model. To attenuate the effects of payload variation and wind disturbances on the system, an adaptive control method based on disturbance observers is devised. Additionally, the uniform boundedness of all error signals is demonstrated. The effectiveness of the designed control method is verified through simulations, which serves to strengthen its applicability in practical applications.

SoftWind: Software-defined trajectory correction modelling of gust wind effects on internet of drone things using glowworm swarm optimization

The dynamic nature of the atmosphere, especially wind gust, poses a crucial challenge to efficient and real-time drone operations. This article presents a novel MQTT based software-defined drone network for trajectory correction of drone flights in gusty wind conditions using Glowworm Swarm Optimization (GSO). By imposing the GSO to the software-defined drone network, our proposed model SoftWind has optimized the navigation and control capabilities of drones by correcting the trajectories in a gusty wind environment. We have analyzed the trajectories and convergence of drones due to wind gusts. As wind disturbances affect the trajectories of drones, we have corrected it by our trajectory correction model and evaluated the direction of the drones must fly to mitigate the wind gust and the resultant velocity compared to the no-wind environment. This study analyzed the trajectories of 100 drone flights due to various wind gust lengths (i.e., 40 m, 10 m, 6 m, and 3 m) for a fixed gust amplitude of 15 m/s and various gust amplitude (i.e., 0 m/s, 5 m/s, 15 m/s, and 40 m/s) for a fixed gust length 5 m. We observed that all the drones are converged to a single point due to low gust length (≤ 5 m) and high gust amplitude (≥ 35 m/s). It is also found that the direction of the drone must fly 28.87°. East of South to mitigate the effect of wind gusts having 10 m gust length and 15 m/s gust amplitude and the resultant velocity of the drone is 22.38 m/s. The result shows that SoftWind reduces the convergence time by 26 %-54 % as compared to other existing models.

Self-immunity study of quadrotor UAV based on Modelica system modeling and disturbance feed-forward compensation

For addressing the challenges of decreased attitude and trajectory tracking accuracy and a delayed response in the flight control operations of quadcopter unmanned aerial vehicles (UAVs) under the uncertainties of model parameters and external disturbances, this study leverages the advantages of the non-causal declarative modeling language Modelica in system modeling and simulation. In addition, it incorporates the nonlinear Active Disturbance Rejection Control (ADRC) framework for disturbance observation, estimation, and compensation. A state observer is designed to mitigate the impact of external disturbances and model uncertainties through feed-forward compensation, and stability analysis is conducted. Numerical simulations for hover resistance demonstrate that, compared to the cascade proportional integral differential (PID) control strategy, PID-NLADRC reduces the maximum deviation induced by wind disturbances by ∼50% and shortens the disturbance influence time by around 40%. Simulations for different trajectories, such as planar or spatial, smooth or abrupt changes, indicate that under the PID-NLADRC control strategy, the real-time spatial distance deviation mean is reduced by 69.5%, and the peak time is shortened by 75.7%. Validation through multi-objective applications and physical experiments highlights the advantages of PID-NLADRC in terms of positioning accuracy, rapid tracking, and disturbance suppression, aligning well with the fast, precise, and robust flight control requirements of quadcopter UAVs.

Analysis of the Causes of the Magnetic Storm on December 1–2, 2023 Based on Observations of Interplanetary Scintillations at the BSA Radio Telescope of the Lebedev Physical Institute

The results of the analysis of observational data of interplanetary scintillations obtained at the Big Synphasic Antenna radio telescope of the Lebedev Physical Institute (BSA LPI) before, during and after the magnetic storm that occurred on December 1–2, 2023. Observational data were compared with model calculations for corotating and propagating large-scale disturbances. The results of observations of scintillations of radio sources indicate that the magnetic storm that took place was caused by the superposition of two types of large-scale disturbances of the solar wind. On the day before the start of the magnetic storm, signs of interaction of the Earth’s magnetosphere with the corotating region of multi-velocity solar wind flows were observed, whereas later signs of disturbance of the magnetosphere by a coronal mass ejection propagating after the M9.8 flare on November 28, 2023 were observed.

The Frequency Regulation Scheme of a Wind Turbine Generator Based on Variable Tracking Operation

This paper proposes a variable-power-tracking-operation-based frequency regulation scheme for a wind turbine generator (WTG) that employs a frequency-excursion-based control parameter to suppress frequency excursion under various wind speeds and disturbances. To this end, an improved system frequency response model is built, and then the frequency regulation characteristics of the WTG are investigated. The frequency-excursion-based control parameter is determined. Simulations based on the Matlab/Simulink simulator verify the effectiveness of the proposed variable-power-tracking-operation-based frequency regulation strategy. The simulation results clearly indicate that the suggested scheme is beneficial for reducing the maximum frequency deviation. The proposed frequency regulation scheme could enhance the networking capacity of wind farms and improve the capacity of the power grid to absorb renewable energy.

Impact of salvage logging on short-term natural regeneration in montane forests of the Alps after large windthrow events

Wind disturbances are one of the main drivers of forest dynamics in Europe, shaping forest stands and modifying the ecosystem services provisioning. Salvage logging is often most common strategy adopted after a high-severity disturbance in managed stands. Understanding natural regeneration dynamics including their interaction with the logging operations, is crucial to understand how forests will be changing under a climate with increasing variability and to design adequate adaptive post-disturbance management strategies. In this study, we focused on 148 stands damaged by storm Vaia (2018). The aim was to analyze natural regeneration dynamics under different logging systems and to investigate influences of site characteristics and disturbance legacies on sapling growth and seedling emergence. The sampling protocol consisted of one transect per stand, perpendicular to one of the intact forest edges, and with a length of 80 m. Along the transect, we collected soil cover, natural seedling and sapling stem density, and deadwood quantity in four sample plots of 3 m radius each at distances of 0, 20, 40, and 80 meters from the edge (592 plots in total). Regeneration species composition was mainly driven by previous stand composition, with some exceptions depending on seed dispersal strategy. Distance from the edge significantly influenced seedlings and saplings occurrence in large gaps and affected the browsing damage percentage, together with deadwood presence. According to GLM’s models, distance from the edge, elevation, and logging methods influenced seedling establishment. At the same time, species characteristics, edge structure, deadwood and logging damages significantly influenced pre-storm seedlings and saplings presence and health. In conclusion site factors, disturbance legacies, and logging strategies are key points to consider in post-disturbance management for a fast forest recovery.

Мониторинг околоземного космического пространства, магнитосферы и атмосферы Земли в периоды Форбуш-эффектов в конце августа 2005 г.

We present the results of near-Earth interplanetary space, magnetosphere, and atmosphere monitoring during large-scale solar wind disturbances at the end of August 2005. The monitoring was carried out using ground-level cosmic ray (CR) observations made at the worldwide network of neutron monitors as well as muon telescopes in Yakutsk and Novosibirsk. As a result of the analysis performed by different methods, we have obtained variation properties of CRs of different rigidities in Earth’s orbit, their pitch angle anisotropy, orientation and configuration of the interplanetary magnetic field, changes in the planetary system of geomagnetic cutoff rigidities during geomagnetic disturbances, as well as mass average air temperature over CR stations equipped with muon telescopes. For the periods of geomagnetic disturbances, we have determined parameters of magnetospheric ring current and magnetopause currents.

Monitoring of near-Earth space, Earth’s magnetosphere and atmosphere during Forbush decreases in August 2005

We present the results of near-Earth interplanetary space, magnetosphere, and atmosphere monitoring during large-scale solar wind disturbances at the end of August 2005. The monitoring was carried out using ground-level cosmic ray (CR) observations made at the worldwide network of neutron monitors as well as muon telescopes in Yakutsk and Novosibirsk. As a result of the analysis performed by different methods, we have obtained variation properties of CRs of different rigidities in Earth’s orbit, their pitch angle anisotropy, orientation and configuration of the interplanetary magnetic field, changes in the planetary system of geomagnetic cutoff rigidities during geomagnetic disturbances, as well as mass average air temperature over CR stations equipped with muon telescopes. For the periods of geomagnetic disturbances, we have determined parameters of magnetospheric ring current and magnetopause currents.

Impacts of microplastic concentrations and sizes on the rheology properties of lake sediments

The information concerning the effects of microplastics (MPs) on lake sediment environment, particularly structural properties, is still scant. This study aimed to investigate the effect of MPs characteristics (including concentration and size) on the sediment rheological properties, which affected sediment resuspension. After 60-day experiments, it was found that (0.5–2 %) MP in sediments decreased sediment viscosity, yield stress, and flow point shear stress by 14.7–38.4 %, 3.9–24.1 % and 13.5–36.5 %. Besides, sediment (with 50 μm MP addition) yield stress and flow point shear stress also dropped by 1.1–14.1 % and 9.6–12.9 % compared to 100 and 200 μm MP addition. The instability in sediment structure could be attributed to MP-induced EPS production and cation exchange capacity (CEC) changes. Accordingly, the decreases in rheological properties induced by different sizes and concentrations MPs might facilitate the sediments resuspension with wind and wave disturbances. The study shed light on previously overlooked environmental issues caused by MPs characteristics from a new perspective, thereby enhancing our understanding about the environmental behavior of MPs in lake sediment ecosystems.

Function observer based on model compensation control for a fixed-wing UAV

Fixed-wing unmanned aerial vehicle (UAV) is a nonlinear system characterized by strong coupling, high complexity, and sensitivity to external interference and model uncertainty. For the fixed-wing UAV having eight degrees of freedom, the uncertainty and wind disturbance parts of the model are clarified, and a model with lump disturbance is established through the mechanic analysis. To get the high performance of control, a highly accurate observer for the lump disturbance is necessary. A second-order compensation function observer (CFO) with feedforward is proposed with new structure. The CFO accuracy is much higher than the same order of the extended state observer (ESO) by convergence analysis. A hyperbolic tangent function is combined with the CFO for effectively reducing the large estimation error at the initial moment. A CFO-based model compensation control (MCC) algorithm is provided for controlling the longitudinal and lateral channels of the fixed-wing UAV. The MCC contains the known model, the compensation of unknown model via the CFO, feedback of error and the dynamic information of the given information. The MCC realizes the desired linear characteristics for the feedback system because it decouples the channels, restrains the lump disturbance. The stability of the closed-loop system is proved by Lyapunov theorem. The proposed CFO-based MCC is applied to the fixed-wing UAV, and compared with the traditional PID and ESO-based on sliding mode control (SMC) algorithm through simulation and the control test platform experiment based on Pixhawk, showing the superiority of the MCC and highly accuracy of the CFO.