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Patients with alopecia areata (AA) may experience episodic disease flares characterized by increasing hair loss that follow a seasonal pattern. However, no studies have examined whether specific climate factors contribute to the seasonal pattern of AA flares. Using Spearman rank correlation analyses, we assessed the association between climate variables and AA flare frequency per month in 336 children with AA in Philadelphia, Pennsylvania. Region-specific monthly values for average ambient temperature, air pressure, cloudiness, hours of sunlight, relative humidity, number of days with sun, number of days with rain, volume of precipitation, wind gust, wind speed, and UV index from January 2015 to December 2017 were obtained from World Weather Online. We found significant (P

Steel lattice towers have large application in meteorology, and are regularly exposed to loads difficult to determine reliably, like wind and ice, and especially wind gusts and accompanied structural vibrations. EN 1993-3-1 treats such structures and requires checking of vibrations, but does not supply methodology for it, neither allowed values for deformation and vibrations. The paper presents analysis of a tower 110 m high using the Finite Element Method (FEM), in case of wind gust, for iced and non-iced structure, both statically and dynamically. The results were compared and recommendations for future treatment of such sensitive structures were given.

This study estimated the wind gust factor and turbulence intensity for hurricane winds that are modeled as a nonstationary non-Gaussian process. The estimation considered the time-varying m...

Wind energy is one of the premier renewable energy sources that have gained popularity during the last decade. Among the currently available wind energy conversion systems (WECS), doubly fed induction generator-based technology has been widely employed due to its superior advantageous. The key features of the DFIG-based WECS include its ability to capture more wind energy and support the grid with large reactive power during short disturbance events. On the other hand, DFIG is very sensitive to grid faults which affect its fault ride through (FRT) capability. Furthermore, extreme wind gust even for short durations may lead to the violation of the low voltage ride through (LVRT) threshold limits set by worldwide transmission line operators. This situation cannot be mitigated by the turbine blades pitch controller since the response of the pitch mechanical control is much slower than the rapid dynamic change in the wind speed during short duration of wind gust events. While DFIG FRT capability has been discussed in several papers in the literature, not much attention was given to the mitigation of the effects of extreme wind gust of short duration on the DFIG performance. In this paper, the effect of various levels of wind gust on the performance of a DFIG-based wind energy conversion grid-connected system is investigated and mitigated using a new controller for superconducting magnetic energy storage (SMES) unit. A combination of hysteresis current and fuzzy logic controllers is employed to control the voltage source converter and the DC-DC chopper interfacing the SMES coil with the investigated system. Simulation results reveal the effectiveness of the proposed SMES controller that can be easily implemented within existing as well as new WECS installations.

This article presents the design and evaluation of a robust C⁎ control law through Hardware-In-the-Loop Simulation (HILS) of JAXA’s research aircraft called Multi-Purpose Aviation Laboratory (MuPAL-α). The C⁎ control law, which is a widely used flight control architecture in aviation industries, is designed using structured H∞ synthesis. This design method provides robustness of the controller for flight condition changes and uncertainties associated with the dynamics of MuPAL-α. HILS tests allow on-ground evaluation of controllers using actual actuators. The HILS results show that the designed controller adequately tracks pilot commands in the presence of airspeed variation, uncertainties in the modeling of the onboard actuators, and wind gust.

Usually, the analysis of structures under wind loading is performed using an equivalent static analysis, where the influence of floating response is taken into account by the gust factor. This methodology can be used in case of rigid structures for not presenting a considerable dynamic response. More flexible structures, in particular those lightly damped, may show an important resonant response and their dynamic properties must be considered in the analysis. The aim of this paper is to present a methodology for dynamic analysis of structures under wind loading considering the geometric nonlinearity, the vibration caused by the kinetic energy of wind gusts and the aerodynamic damping due to the relative movement between this structure and the wind. The formulation proposed is applied to a 180-meter-high concrete chimney and the results were compared with those obtained through the recommendation given in the standard ABNT NBR 6123:1988 [2] for the dynamic structural analysis.

The active anti-roll bar system has been proven to be one of the most effective solutions to improve roll stability of heavy vehicles. In a previous work, the authors proposed an H∞ controller for this system. The Genetic Algorithms method was used to handle the vehicle roll stability and the energy consumption of the actuators via the Pareto optimality. This paper aims to assess the overall effectiveness of the proposed controller with nonlinear heavy vehicle models, which are already set up in the TruckSim® software. The controller is then evaluated in hard conditions to show the high performance and robust with the nonlinearity effects, such as the load distribution between the two axles, the side wind gusts and the abrupt steering. To conduct testing of the H∞ active anti-roll bar control system, we propose a co-simulation structure between TruckSim® and Simulink®: the nonlinear vehicle model is determined from TruckSim®, based on using the block S-function of Simulink. Meanwhile, the controller and the actuators are built directly in the Matlab/Simulink ® environment. The validation results are made through two different types of heavy vehicles: a tour bus and a truck, using a selection of different velocities and scenarios. The results show that by using the H∞ active anti-roll bar control system, in comparison to the passive anti roll bar system, roll stability is improved to minimise the risk of vehicle rollover.

We conduct a systematic and comprehensive comparison of state-of-the-art postprocessing methods for ensemble forecasts of wind gusts. The compared approaches range from well-established techniques to novel neural network-based methods. Our study is based on a 6-year dataset of forecasts from the convection‐permitting COSMO‐DE ensemble prediction system, with hourly lead times up to 21 hours and forecasts of 57 meteorological variables, and corresponding observations from 175 weather stations over Germany. We find that simpler methods such as ensemble model output statistics (EMOS), member-by-member postprocessing and a novel isotonic distributional regression approach, which utilize ensemble forecasts of wind gusts as sole inputs, already result in improvement in terms of the mean CRPS of up to 40% compared to the raw ensemble predictions. This can be substantially improved upon by more complex machine learning methods such as gradient boosting-based extensions of EMOS, quantile regression forests, and variants of neural network-based approaches that are capable of incorporating additional information from the large variety of available predictor variables.

The NASA spacecraft has also snapped more shots of its surroundings and listened to a Martian wind gust. The NASA spacecraft has also snapped more shots of its surroundings and listened to a Martian wind gust.

Modern building standards are universal and applicable to the calculation of any structures with one or another measure of stock. However, the calculation of specific groups of structures requires detailed consideration and clarification. The article suggests some refinements in calculating of the high-rise structures made of metal for the pulsating component of the wind load.

Durability and load-bearing are difficult to be combined in engineering systems. Hence, in majority of man-made structures, the two characteristics are typically mutually exclusive. Nature, however, has provided us with design strategies, through which many biological systems have overcome this conflict. Insect wings represent a striking example of such a combination. A key to this lies in the presence of vein joints. Here we 3D printed bio-inspired joints, akin to those of insect wings and tested their mechanical performance under both static and cyclic loadings. We used the so-called ‘flexible joints’, which had a high durability, and engineered them to further enhance their load-bearing capacity. We then implemented them into the design of the first 3D printed bio-inspired kite. The manufactured kite showed a stable flight and withstood loads induced by strong wind gusts without failure. The concept developed here can be applied to other engineering designs that pursue a compromise between load-bearing and durability. At the end, we used our data to better understand the complexities of insect wings with respect to their local and global deformations and fracture resistance.

Severe convective storms (SCSs; tornadoes, large hail, and damaging convective wind gusts) can produce socioeconomic impacts ranging from billion-dollar hailstorms to deadly tornado outbreaks. Weather-sensitive economic sectors (e.g., agriculture, aviation, insurance, logistics) impacted by these mesoscale extreme events have evolved to anticipate and, in some cases, mitigate their impact; however, these expectations may be disrupted by shifts in the climatological frequency, intensity, and efficiency of these storm-scale extremes in a future climate. In addition to a changing climate, it is not yet well understood why some years tally record high SCS reports, whereas others exhibit record low counts. Ultimately, understanding how climate regimes may modify these relatively low probability—but high impact—events could help reduce this uncertainty, thus empowering stakeholders to anticipate change, mitigate impacts, and incorporate resiliency strategies. More research is needed, particularly using novel computational methods such as dynamical downscaling and machine learning to understand the full impact that climate variability and change may have on these extreme weather events.

A time series is a sequence of observations, measured at certain moments in time, ordered chronologically and evenly spaced, so that the data are usually dependent on each other. Currently, time series are used to estimate wind gusts, which are highly non-linear, unknown, and at times unpredictable. A good estimation of wind gusts implies correct planning on the generation of clean wind energy. In this work, we use Artificial Intelligence (AI) techniques such as the use of convolutional neural networks for wind gust estimation. One of the best models for dealing with this type of information is the Large Short Term Memory (LSTM) network because it is a type of recurrent network that specializes in sequence information. In this work, an LSTM prediction model is implemented for five different wind speed data sets using different multi-step forecasting strategies. The strategies used are Recursive, Direct, MIMO (multiple-input to multiple-output), DIRMO (Combination of direct strategy and MIMO), and DirREC (Combination of direct and recursive strategy).

In this paper, the transient stability of the wind integrated power system has analyzed with or without a battery energy storage system (BESS) and static compensator (STATCOM) under large disturbances. The large penetration of wind energy into the power grid is the major challenge for reliable and stable operation of the system. The transient stability of such type of power systems can be improved by utilizing the BESS and STATCOM. In this paper, the large disturbances such as a sudden change in load demand, three-phase fault, sudden change in wind speed, and wind gust have investigated. The energy storage system such as BESS is utilized with wind farms in order to modulate the fluctuations in power output. It also improves the response of synchronous generators to transient events. The paper also highlights the effective control of BESS and STATCOM for transient stability improvement. For validation of the proposed techniques, the IEEE 14 bus test system has utilized. All the simulation studies have been performed with DlgSILENT PowerFactory 2018.

Forest ecosystems are faced with a variety of threats, including increasingly prolonged droughts and other abiotic stresses such as extreme high temperatures, very strong wind, invasive insect outbreaks, and the rapid spread of pathogens. The aim of the study was to define crucial abiotic stressors affecting Central Europe forest ecosystems and, with regard to their possible simultaneous effect, develop a universal method of multi-hazard evaluation. The method was then applied to the particular area of interest represented by part of the Czech Republic with forest land cover (12&ndash, 19&thinsp, &deg, E, 48&ndash, 51&thinsp, N). Based on National Threat Analysis, the most significant threats of natural origin with a close relationship to forest stability were identified as drought, high temperature, and wind gusts. Using suitable indicators, a level of their risk based on occurrence and consequences was estimated. The resulting combined level of risk, divided into five categories, was then spatially expressed on a grid map. The novelty of our paper lies in: (i) all relevant climatic data were combined and evaluated simultaneously with respect to the different level of risk, (ii) the developed methodological road map enables an application of the method for various conditions, and (iii) multiple hazards were estimated for the case study area.

Unmanned Aerial Vehicles (UAVs) have been widely applied for pesticide spraying as they have high efficiency and operational flexibility. However, the pesticide droplet drift caused by wind may decrease the pesticide spraying efficiency and pollute the environment. A precision spraying system based on an airborne meteorological monitoring platform on manned agricultural aircrafts is not adaptable for. So far, there is no better solution for controlling droplet drift outside the target area caused by wind, especially by wind gusts. In this regard, a UAV trajectory adjustment system based on Wireless Sensor Network (WSN) for pesticide drift control was proposed in this research. By collecting data from ground WSN, the UAV utilizes the wind speed and wind direction as inputs to autonomously adjust its trajectory for keeping droplet deposition in the target spraying area. Two optimized algorithms, namely deep reinforcement learning and particle swarm optimization, were applied to generate the newly modified flight route. At the same time, a simplified pesticide droplet drift model that includes wind speed and wind direction as parameters was developed and adopted to simulate and compute the drift distance of pesticide droplets. Moreover, an LSTM-based wind speed prediction model and a RNN-based wind direction prediction model were established, so as to address the problem of missing the latest wind data caused by communication latency or a lack of connection with the ground nodes. Finally, experiments were carried out to test the communication latency between UAV and ground WSN, and to evaluate the proposed scheme with embedded Raspberry Pi boards in UAV for feasibility verification. Results show that the WSN-assisted UAV trajectory adjustment system is capable of providing a better performance of on-target droplet deposition for real time pesticide spraying with UAV.

Conventional unmanned aerial vehicles, quadrotor have a plethora of applications for civilian and military purposes. Quadrotors as the name implies usually have four input variables (fixed rotors) which are used to drive six outputs (i.e., 3 translational and 3 rotational motions), and this leads to coupling between motions. Tilt- rotor quadrotors are more versatile because they have more input variables to independently control its orientation and position without coupling. In this paper, a decentralized backstepping control approach is used to generate a new set of inputs capable of independently and simultaneously achieve decoupling of motions while rejecting wind disturbances. The tiltrotor quadrotor dynamic is first decentralized to achieve six subsystems, then controller inputs for each subsystem are generated via Lyapunov based backstepping method whereby the controller parameters are optimized by Differential Evolution (DE) technique. This system exhibits robustness capability because it is able to reject external disturbances.

Improved understanding of wind gusts in complex terrain is critically important to wind engineering and specifically the wind energy industry. Observational data from 3D sonic anemometers deployed at 3 and 65 m at a site in moderately complex terrain within the northeastern United States are used to calculate 10 descriptors of wind gusts and to determine the parent distributions that best describe these parameters. It is shown that the parent distributions exhibit consistency across different descriptors of the gust climate. Specifically, the parameters that describe the gust intensity (gust amplitude, rise magnitude, and lapse magnitude; i.e., properties that have units of length per time) fit the two-parameter Weibull distribution, those that are unitless ratios (gust factor and peak factor) are described by log-logistic distributions, and all other properties (peak gust, rise and lapse times, gust asymmetric factor, and gust length scale) are lognormally distributed. It is also shown that gust factors scale with turbulence intensity, but gusts are distinguishable in power spectra of the longitudinal wind component (i.e., they have demonstrably different length scales than the average eddy length scale). Gust periods at the lower measurement height (3 m) are consistent with shear production, whereas at 65 m they are not. At this site, there is only a weak directional dependence of gust properties on site terrain and land cover variability along sectorial transects, but large gust length scales and gust factors are more likely to be observed in unstable atmospheric conditions.

In this paper, trajectory tracking for a quadrotor unmanned aerial vehicle (UAV) is considered in the presence of a cable-suspended payload and wind as unknown disturbances. It is assumed that the wind disturbance is slowly time varying and affects quadrotor position and orientation independently. Nonlinear robust strategies, such as backstepping and sliding mode control could be used for trajectory tracking; however, they fail to stabilize the system in the presence of payload or wind, or both together. We have proposed a combined backstepping and super-twisting integral sliding mode strategy to stabilize the system. Conventional sliding mode control suggests discontinuous control signals and suffers from the chattering phenomenon whereas its super-twisting integral version suggests continuous control signals, which makes it implementable and chattering free.

Installation of blades for wind turbines is challenging due to large lifting height and high precision. Assessment of blade dynamic responses during installation needs advanced simulation tools which are limited at present. This paper aims at developing an integrated simulation tool SIMO-Aero for single blade installation for both onshore and offshore wind turbines. Based on the cross-flow principle, the aerodynamic model is established by accounting for the effect of wind turbulence and dynamic stall. Then it is coupled with SIMO to achieve the integrated simulation tool SIMO-Aero which can account for blade aerodynamics, vessel hydrodynamics and system mechanical couplings. The aerodynamic code is verified by code-to-code comparisons with HAWC2. Furthermore, SIMO-Aero is applied in case studies on the wind-induced dynamic responses of a DTU 10 MW blade during installation using a jack-up crane vessel which is assumed to be rigid, including the crane, and rigidly fixed to the seabed. The characteristics of system dynamic responses prior to mating the blade onto the hub are studied. It is shown that the blade motions are dominated by the pendulum motion. Critical parameters of the installation process are identified. The extreme responses of critical parameters are further studied under turbulent winds and wind gusts.

This paper addresses the trajectory tracking control problem for small-scale unmanned helicopters with model uncertainties. In particular, we propose a robust control scheme that is decomposed into a position and an attitude control modules, operating in a cascaded form, and does not depend on the explicit knowledge of the value of the model parameters. Exploiting the concepts and techniques of prescribed performance control, each module guarantees trajectory tracking with prescribed transient and steady-state response, despite the presence of external disturbances, such as wind gusts and ground effect phenomena. Additionally, a novel reformulation of the translational dynamics reveals a sufficient condition for closed-loop stability and allows us to extract the appropriate attitude commands straightforwardly. Moreover, the derived control algorithms are of low complexity and thus can be efficiently implemented on low-cost, aerial embedded systems of limited power and computational resources. Finally, the efficacy of the proposed control scheme is verified via extensive experimental studies using an autonomous small-scale helicopter.

The continuous rise of off-shore activities such as the development of wind farms requires a reliable operational support in order to minimize cost drawbacks and secure operations during the different stages of associated projects. One of the most important parameters for this kind of analysis is wind gustiness. The objective of the study is the development of a methodology for the surface wind gust estimation based on Numerical Weather Prediction Models and statistical post processing. The obtained method has been tested over the offshore west coastline of the United States and evaluated utilizing observational data from the NOAA’s buoy network.

International audience; Lightweight Unmanned Aerial Vehicles (UAV) are usually very sensitive to the external disturbances during outdoor experimentations. These adverse conditions make both the dynamic modeling and the control tasks more complex. Thus, it is necessary to employ an efficient control technique with acceptable performance without a complete knowledge of the disturbed model. This is because, in the classic feedback linearization control, the deviations between the model and the real plant may produce poor performance. Throughout the present paper, Dynamic Sliding Mode Control (DSMC) technique is designed to deal with the disturbances and which has never been used for quadrotors. Unlike the existing sliding mode techniques, the designed one uses an input-dependent sliding surface in order to enhance the robustness level of the classical feedback linearization control law. The effectiveness of this approach that ensures 3D trajectory tracking of quadrotor is demonstrated through numerical simulations.

Frequency control represents a critically significant issue for the enhancement of the dynamic performance of isolated micro grids. The micro grid system studied here was a wind−diesel system. A new and robust optimization technique called the mine blast algorithm (MBA) was designed for tuning the PID (proportional−integral−differential) gains of the blade pitch controller of the wind turbine side and the gains of the superconducting magnetic energy storage (SMES) controller. SMES was implemented to release and absorb active power quickly in order to achieve a balance between generation and load power, and thereby control system frequency. The minimization of frequency and output wind power deviations were considered as objective functions for the PID controller of the wind turbine, and the diesel frequency and power deviations were used as objective functions for optimizing the SMES controller gains. Different case studies were considered by applying disturbances in input wind, load power, and wind gust, and sensitivity analysis was conducted by applying harsh conditions with varying fluid coupling parameter of the wind−diesel hybrid system. The proposed MBA−SMES was compared with MBA (tuned PID pitch controller) and classical PI control systems in the Matlab environment. Simulation results showed that the MBA−SMES scheme damped the oscillations in the system output responses and improved the system performance by reducing the overshoot by 75% and 36% from classical and MBA-based systems, respectively, reduced the settling time by 45% compared to other systems, and set the final steady-state error of the frequency deviation to zero compared to other systems. The proposed scheme was extremely robust to disturbances and parameter variations.

The paper discusses the effect of a wind gust with a realistic shape occurring simultaneously with a grid fault. For wind power plants with variable-speed pitch-regulated wind turbine generators, considered are fault scenarios for which no fault ride-through violation occurs in the absence of wind variation and a simultaneous gust assuming that the wind speed remains between the cut-in and cut-out values. Discussed are characteristics of wind gusts and evidence of their role, limitations of wind power plant models intended for actual stability studies and factors of influence. The effect is illustrated by PSS/E simulations for large power systems with wind power plants based on Type 2, 3 and 4 wind turbine generators. A framework for further investigations of the need to account for wind gusts in stability and fault ride-through studies is outlined.

An hybrid autogyro aircraft with wind energy conversion using autorotation is proposed. The fixed wing addition to classic autogyro assists the aircraft lifting reducing speed minimum wind for the flight. A PID control strategy is used to attitude aircraft stabilization. In order to verify the generation of energy, the relationship between energy and wind speed are recorded during experimental flights.

We have developed and tested several dynamic models of the parafoil system descending in Titan's atmosphere. These dynamic models include a progression from point mass models to rigid multibody models, including relative dynamics between canopy and payload. In these models, we have included wind models used for Titan simulation, and extrapolated wind gust models previously used for simulation in the Martian environment. We have also developed guidance and control techniques for autonomous parafoil turning in the adverse wind environment. Finally, and in order to improve the controller performance by reducing the uncertainty to environmental factors, we have also developed ways to estimate the Titan environmental parameters, i.e. the atmospheric density, and the wind magnitude, during the descent. A more complete and realistic simulation is being developed, which uses JPL's DSENDS Entry, Descent, and Landing Software framework.

The wind data persistence provides useful information about the climatological characteristics of a given location. Particularly, the wind gusts persistence should be taken into account in many studies such as site selection for wind turbines and synthetic generation of the wind gusts data. In this paper we examine the long-term persistence of daily wind gusts data with many years of record using the fractal dimension. The persistence measures the correlation between adjacent values within the time series. Values of a time series can affect other values in the time series that are not only nearby in time but also far away in time. For this purpose, an elaborated method to measure the fractal dimension of temporal discrete signals is presented. The fractal dimension is then used as criterion in the proposed approach to detect the long term correlation in wind gusts series. The results show that daily wind gusts are anti-persistent.

The control of the unmanned aerial vehicles is a difficult problem because of their light weight and the strong coupling between the longitudinal and lateral modes. Motivated by this, a backstepping and dynamic inversion-based automatic landing system is designed in this paper for the flight control of a fixed wing unmanned aerial vehicle subject to wind shears, atmospheric disturbances, and wind gusts. Two backstepping-based controllers are designed for the stabilization of the attitude angles, while the controller associated to the forward velocity uses the dynamic inversion technique to obtain a constant forward velocity during all the three stages of landing. To provide an estimation of the wind shears, atmospheric turbulences, and wind gusts, a nonlinear disturbance observer is introduced in the control architecture. The lateral deviation with respect to the runway is canceled while the unmanned aerial vehicle maintains its desired trajectory slope angle. The novel adaptive automatic landing system is software implemented and validated by complex numerical simulations; the results of the numerical simulations prove the stability and robustness of the new control architecture for different initial conditions and wind type disturbances.

The usage of Micro Aerial Vehicles (MAVs) is rapidly emerging in the mining industry to increase overall safety and productivity. However, the mine environment is especially challenging for the MAV's operation due to the lack of illumination, narrow passages, wind gusts, dust, and other factors that can affect the MAV's overall flying capability. This article presents a method to assist the navigation of MAVs by using a method from the field of Deep Learning (DL), while considering a low-cost platform without high-end sensor suits. The presented DL scheme can be further utilized as a supervised image classifier that has the ability to process the image frames from a single on-board camera and to provide mine tunnel wall collision prevention. The efficiency of the proposed scheme has been experimentally evaluated in two mine environments that were used for data collection, training, and corresponding testing under multiple flying scenarios with different cameras configurations and illuminations., https://youtu.be/uJFvTGnrPAY

The issue of tree instability and failure, particularly during windstorms or wind gusts, is of great concern. Its extensive impact on public safety is becoming more widely acknowledged. When blowing at critically high speed, the kinetic energy carried by winds, loading onto trees, may forcefully exceed tree strength. This may cause the stem to break, the trunk to split, or the entire tree to be uprooted. Even if surviving bursts of strong wind, the structural elements of trees may have undergone irreversible plastic deformation. Permanently damaged trees have a greater risk of failure and they need to be properly trimmed, pruned, or removed. Realizing these dangerous wind effects, it follows that the assessment of dynamic wind loading on tree stress and stains is a key to preventing tree hazards. We have developed a small-scale inertial measurement sensor unit on a single-board microcontroller. Attached to a tree branch, it constantly measures a time series of oscillatory motion of the branch in response to natural wind forces. Decomposing this signal into its constituent spectral components, the tuned mass damping effects of tree sways can effectively be estimated. Our experiments verified and validated that the wind directions can be determined, relative dynamic wind loads can be approximated, types of trees can be categorized, and the signal energy of tree swaying accelerations can be analyzed. Affordability and ease of use of our device make it highly practical to monitor not only multiple trees at once but also many branches of a single tree. Resulting analysis benefits tree management teams and landscape architects, assisting them in assessing which trees to prune and when.

This paper summarizes results acquired from the fatigue testings of two full-scale dynamic message signs (DMSs) fabricated by a local manufacturer in the United States. One DMS with adhesive joints and one DMS with welded joints were tested with fatigue loading. For the testing, each of the DMSs was loaded up to 500,000 cycles with a force ranging between 0.249 kN and 0.818 kN equivalent to the design natural wind gust pressure based on a yearly mean speed of 18.02 km/h according to the AASHTO LRFD Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals. Strain, displacement, and load were recorded during each test to analyze the structural adequacy of tested DMSs. During the testing, all the stress ranges observed in each of the tested DMSs were considerably below the threshold of the DMS panel, which was determined by generating its S-N curves. The maximum deflection range was found to be highest near the center for both adhesive and welded DMSs when encountered with the fatigue loads. It is recommended that additional stiffeners be installed to reduce the deflection range of the DMS at the center. It was also found that any damage was not observed in both the adhesive and welded DMSs due to the fatigue loading.

When a train moves through the air, a region of air moves along with it at approximately the same speed: this region of air is known as the ‘slipstream’. Numerical simulations were conducted in order to simulate the slipstream around a model-scale freight train when subjected to crosswinds with two different yaw angles; 10° and 30°. The results were compared to a previous slipstream study without a crosswind. The velocities on the windward side of the train for each case are mostly lower than the crosswind speed due to the flow stagnation on the side of the train. In general, crosswind velocities are lower than those in the no-crosswind case. On the leeward side, velocities from the 30° crosswind case remain higher than train speed for more than two metres from train side. Peak instantaneous velocities showed strong dependence on yaw angle and position from train side as well as exhibiting superficial comparison to full-scale data. Velocities were used as inputs to a spring-mass-damper model which modelled human responses to wind gusts. The effect of a crosswind on the train's slipstream significantly increased the likelihood of a person becoming unsteadied while standing on the leeward side of the train.

To analyze the parachute dynamics and stability characteristics of precision airdrop system, the fluid–structure interaction (FSI) dynamics coupling with the flight trajectory of a parachute–payload system is comprehensively predicted by numerical methods. The inflation behavior of a disk-gap-band parachute is specifically investigated using the arbitrary Lagrangian–Euler (ALE) penalty coupling method. With the available aerodynamic data obtained from the FSI simulation, a nine-degree-of-freedom (9DOF) dynamic model of a parachute–payload system is built and solved to simulate the descent trajectory of the multi-body dynamic system. Finally, a linear five-degree-of-freedom (5DOF) dynamic model is developed, the perturbation characteristics and the motion laws of the parachute and payload under a wind gust are analyzed by the linearization method and verified by a comparison with flight test data. The results of airdrop test demonstrate that our method can be further applied to the guidance and control of precision airdrop systems.

Operating cranes is challenging because payloads experience large and dangerous oscillations, especially when the system is suffering from wind disturbances and the large-size payload is modeled as a distributed-mass model. The payload oscillations induced by both intentional motions commanded by the human operator and by the external wind disturbances make the dynamics more complicated. This paper presents a novel combined control architecture to limit oscillations of the distributed-mass payload caused by both human-operator commands and wind disturbances. While a smoothed command suppressed operator-induced oscillations, a wind-rejection command eliminated the payload swing resulting from the wind gusts. Through simulations, a large range of system parameters and motions are analyzed to investigate the dynamic behavior of bridge cranes with distributed-mass beams and wind disturbances by using the new control scheme. Experimental results obtained from a small-scale bridge crane validate the simulated dynamic behavior and the effectiveness of the proposed method.

Experimental results of the truck-induced wind gust pressure were used as the basis to develop the equivalent static truck-induced wind pressure for fatigue design in the American Association of State Highway and Transportation Officials (AASHTO). The development does not explicitly quantify the stress range distribution, nor does the development discuss the implied reliability. No recommendation is given to consider truck-induced pressure for fatigue design in the Canadian Highway Bridge Design Code (CHBDC). This study quantifies the stress range due to truck traffic, and calibrates the equivalent static truck-induced wind pressure for fatigue design of overhead steel sign support structures. The reliability-based calibration is focused on the CHBDC. For the vertical excitations, the calibrated pressure is less than 50% of that suggested in the AASHTO. For the horizontal excitations, the calibrated pressure can be greater or smaller than that for the site-dependent natural wind gusts. Therefore, the truck-induced horizontal wind pressure could govern the fatigue design for some sites.

Gantry cranes used for container handling at container terminals (hereinafter referred to as cranes) have experienced unexpected runaways caused by wind. In the present paper, a method of dynamic simulation analysis for runaway of cranes caused by wind is described and the dynamic behavior of a standard-size crane while approaching runaway and after runaway as a result of a wind gust was clarified. In the dynamic simulation analysis, the crane was modeled by combining three-dimensional finite elements. The interaction forces generated between the wheels and the rails and the braking force of the rail clamps used to prevent crane runaway as a result of wind were modeled and calculated. The time change of wind velocity of a wind gust was modeled in terms of the increase ratio and the time change rate, and the wind load acting on the crane was calculated. Based on these models, a standard-size crane was analyzed herein. According to the analysis results, when the gust acted in the rail direction under the condition in which the friction coefficients between the pads of the rail clamps and the rails and those between the wheels and the rails decreased, the sea-side clamp pads and driving wheels entered the slip state, after which the land-side clamp pads and driving wheels entered the slip state. Then, the entire crane started to run away. Due to the time lag like this, the crane may run away even though the total wind load is smaller than the total resistance force acting to prevent runaway, which is simply calculated as the sum of the maximum static friction forces generated between the clamp pads and the rails and between the wheels and the rails. Moreover, although the increase ratio of the wind velocity is small, if a wind gust having a large time change rate blows and the fluctuation of the inertial force in the rail direction becomes large as a result of the swinging of the upper part of the crane, the probability of crane runaway increases when the inertial force increases in the runaway direction.

We present a comparative study of model predictive control approaches of two-wheel steering, four-wheel steering, and a combination of two-wheel steering with direct yaw moment control manoeuvres for path-following control in autonomous car vehicle dynamics systems. Single-track mode, based on a linearized vehicle and tire model, is used. Based on a given trajectory, we drove the vehicle at low and high forward speeds and on low and high road friction surfaces for a double-lane change scenario in order to follow the desired trajectory as close as possible while rejecting the effects of wind gusts. We compared the controller based on both simple and complex bicycle models without and with the roll vehicle dynamics for different types of model predictive control manoeuvres. The simulation result showed that the model predictive control gave a better performance in terms of robustness for both forward speeds and road surface variation in autonomous path-following control. It also demonstrated that model predictive control is useful to maintain vehicle stability along the desired path and has an ability to eliminate the crosswind effect.

With the improvement of the quality of construction materials and the development of construction technologies, large-scale long-span steel frame buildings have been built recently. The P.E.B system using tapered members is being employed as an economically-efficient long-span structure owing to its advantage of being able to distribute stress appropriately depending on the size of sectional areas of members. However, in December 2005 and in February 2014, P.E.B buildings collapsed due to sudden loads such as snow loads and wind gusts. In this study, the design and construction of the P.E.B system in Korea were analyzed and its structural safety was evaluated using the finite element analysis program to suggest how to improve the P.E.B system in order to promote the efficient and rational application of the system.

Gusts of wind with high speed can adversely affect the operation of the electric railway vehicles. These vehicles are able to move and to obtain a high performance, as long as the power supply is ensured. The variation of the vertical forces for maintaining contact between pantograph and catenary may cause interruption of the power supply of the electric railway traction vehicles. The placement of the capture equipment on the vehicle body determines appearance of aerodynamic forces acting on it. To see which are the vertical forces introduced by wind on active capture equipment, used at locomotives LE 060 EA of 5100 kW, we considered the EP3 type of pantograph as model. This was modelled at scale 1:1 taking into account the placement on the body of the locomotive. For the simulation of wind we considered three point values of its speed (10 m/s, 20 m/s, 30 m/s) and angle of eight values that are within the range of 0 deg – 180 deg. With the results of the simulation we have done a comparative analysis on the additional vertical forces introduced by wind for the cases analyzed.

This paper discusses the processing of the wind loads measured in wind tunnel tests by means of multi-channel pressure scanners, in order to compute the response of 3D structures to atmospheric turbulence in the time domain. Data compression and the resulting computational savings are still a challenge in industrial contexts due to the multiple trial configurations during the construction stages. The advantage and robustness of the bi-orthogonal decomposition (BOD) is demonstrated through an example, a sail glass of the Fondation Louis Vuitton, independently from any tentative physical interpretation of the spatio-temporal decomposition terms. We show however that the energy criterion for the BOD has to be more rigorous than commonly admitted. We find a level of 99.95 % to be necessary in order to recover the extreme values of the loads. Moreover, frequency limitations of wind tunnel experiments are sometimes encountered in passing from the scaled model to the full scale structure. These can be alleviated using a spectral extension of the temporal function terms of the BOD.

Consumer demand has increased for pastured poultry products as the drive for sustainable farming practices and ethical treatments of livestock have become popular in the press. It is necessary to identify the important meteorological factors associated with the prevalence of Salmonella in the pastured poultry settings since the presence of Salmonella in the environment could lead to contamination of the final product. The objective of this study was to develop a model to describe the relationship between meteorological factors and the presence of Salmonella on the pastured poultry farms. The random forest method was used to develop a model where 83 meteorological factors were included as the predicting variables. The soil model identified humidity as the most important variable associated with Salmonella prevalence, while high wind gust speed and average temperature were identified as important meteorological variables in the feces model. The developed models were robust in predicting the prevalence of Salmonella in pastured poultry farms with the area under receiver operating characteristic (ROC) curve values of 0.884 and 0.872 for the soil model and feces model, respectively. The predictive models developed in this study can provide users with practical and effective tools to make informed decisions with scientific evidence regarding the meteorological parameters that are important to monitor for increased on-farm Salmonella prevalence.

Coherent Doppler lidar (CDL) has long been used to automatically identify gust front-induced wind shear signatures from the velocity data, but rare attention has been given to the fine structure of wind gust fronts. In this work, a compact and robust CDL with high efficiency and accuracy is equipped at Lanzhou Airport (103°49 ′ E, 36°03 ′ N) to conduct interpretation of wind gust front structures by using high-resolution CDL data. Outflows of gust fronts could be detected reliably from radial velocities, spectral widths, as well as radial shears. For the case study presented here, photographs of the velocity and spectrum width capacitates gust front characteristics such as height, advance speed, and radial shear, as well as vertical structure to be displayed in minute detail. Besides, the quasi-continuous vertical wind reveals the potential turbulent mixing and vertical transport process during the gust front event, which makes CDL a very attractive and essential technique for future development of gust front automatic detection systems.

Torsion irregularity increases the risk of building failure during a strong dynamic excitation that is generated by earthquakes or wind gusts. To enhance the safety and performance of torsional irregular buildings, a newly developed Integrated Control System (ICS) is proposed in this research. The new control approach was applied to a two-way eccentric Benchmark 9-story steel building, constructed for the SAC steel project in California, where each floor is represented by two translational and one rotational degree of freedom. The performance and effectiveness of the ICS were examined and compared with a Tuned Mass Dampers (TMDs) approach by subjecting the building to real earthquake excitations of N-S and E-W components of El Centro in 1940, Loma Prieta in 1989, and Kocaeli, Turkey in 1999. Results showed that the ICS was effectively mitigating the lateral and coupling vibrations by the new design configuration and arrangement for both tuning and detuning cases. The ICS is also more robust in restricting the inter-story drift ratio as compared with TMDs.

This paper concentrates on aerial magnetic sensing with an autonomous Scout B1-100 UAV helicopter. A high-resolution 3-axis mag- netic sensor has been mounted on the helicopter in order to generate a detailed magnetic map and to identify various ferrous objects in the soil. The development is based on advanced mission planning for the UAV as well as test flights under challenging weather conditions such as wind gusts and snow fall. Finally, this paper summarizes a real-world application after the collapse of a daylight coal mining where various persons have been killed and multiple infrastructure objects have been buried. The task of magnetic scanning was applied in order to find buried vehicles where miners have been expected based on eyewitnesses during the collapse. However, while several ferrous objects have been located, the van could not be identified in the extensive area of the landslide.

In the present work, a numerical study aimed to analyse the effect of an extreme loading event on a Horizontal Axis Wind Turbine (HAWT) is performed. A 3D unsteady CFD model of the NREL Phase VI small-sized wind turbine is validated against experimental data, with the incompressible solver of ANSYS Fluent and an unstructured moving mesh strategy. Then the Extreme Operating Gust (EOG) model from IEC 61400-2 is considered as the inlet condition. The results of the aerodynamic response and of the structural ultimate check, based on the IEC guidelines, are presented for both the operating and the parked turbine, in order to underline the benefit of the safety position in terms of lower stress transferred to the critical root section.

International audience; The paper addresses a robust navigation strategy of a rotorcraft class having a simple robotic arm to perform rapid in-flight retrieving operations in presence of wind gusts and aerodynamic effects. The target-acquiring trajectory planner is based on a cosinusoidal dynamic pattern. The mathematical model is extended to account not only the dynamics of the robotic arm but also the aerodynamics. The navigation control scheme is based on a soft integral sliding-mode control (ISC) to stabilize both inner-and outer-loop dynamics regarding the rejection of not only the dynamic couplings but also aerodynamic disturbances. Detailed simulations including realistic aerodynamic effects results show the validity of the proposed navigation strategy while tracking the object-to-retrieve trajectory.

The interaction between a human driver and an automated driving system may improve when the automation is designed in such a way that it behaves in a human-like manner. This paper introduces a human-like steering model, in which the driver adapts to the risk due to uncertainty in the environment. Current steering models take a risk-neutral approach, while the fields of economics and sensorimotor control suggest that humans exhibit risk-sensitive behavior. The proposed model uses a risk-sensitive optimal feedback control structure to predict steering behavior. The paper studies the effect of the risksensitivity parameter and compares the prediction of the riskneutral and risk-sensitive controllers in a simulated abstraction of two scenarios: (a) driving while being subjected to lateral wind gusts and (b) overtaking an unpredictably swerving car. The simulation results show that the risk-sensitive model adapts to the uncertainty in the environment. Experimental data will be needed to validate the predictions of our model.