Wind Resistance Research Articles

The hardest-hit home run?

We present a problem to be assigned or done as an in-class activity in an upper-division undergraduate course on computational physics. The problem involves a home run hit by Mickey Mantle on May 22, 1963, which he famously called “the hardest ball I ever hit.” Is this home run truly one for the record books, or has it been eclipsed by players in the modern era? Modeling the trajectory of a baseball involves consideration of both wind resistance and the Magnus effect and is an interesting application of numerical solutions to ordinary differential equations. Ultimately, the answer is that Mantle would compare favorably to the most powerful batters currently playing, but to arrive at that conclusion we must reflect on the plausibility of results and sources of uncertainty.

Development of Wall Hammering Inspection Systems Using Two-Wheeled Multi-Copters

In this study, we investigated inspection robots that can safely, accurately, and quickly perform hammer sound inspections on tile exterior walls and present new wall hammering inspection systems using two-wheeled multi-copters. Our results yielded the following five advantages. First, the proposed multi-copter can use its wheels not only to move freely on the walls of buildings but also to overcome obstacles on the walls. Therefore, almost any tile wall surface can be inspected for hammering sound. Second, the multi-copter was equipped with both hammer-shaped rods to hit the tile exterior wall and microphones to collect the hammer sound of the tile, while moving quickly on the wall surface. Third, the wall hammering inspection systems can be used safely with a work assistance mechanism using a wire even in densely populated areas, such as urban areas, because the multi-copter has high wind resistance against crosswinds by both pushing against the wall and operating by the wire. Fourth, we presented some automatic control systems that make the multi-copter operation easy during hammering inspections and demonstrated its usefulness through experiments. Fifth, we proposed useful methods for detecting floating tiles based on the hammering results, conducted some outdoor flight experiments on building exterior walls, and demonstrated that floating tiles can be determined with high accuracy.

Chaotic behavior and multistability of a tree trunk structure driven by self-and parametric hydrodynamic forces

Abstract This study investigates the chaotic behavior of a tree trunk under dynamic
wind loads, focusing on control strategies and multistability. We consider time varying wind speeds and analyze a specific case where hydrodynamic drag forces align
with the flow velocity. The stability of the model’s equilibrium points is analyzed
theoretically and numerically. Melnikov’s method is employed to identify conditions
for homoclinic bifurcation. Numerical simulations employing basin of attraction
confirm the analytical predictions. Our findings show a decrease in the threshold
for chaos with increasing amplitudes of external excitation, damping coefficient,
and parametric damping. The global dynamics are explored numerically using a
fourth-order Runge-Kutta method. When solely subjected to external excitation, the
system exhibits period doubling bifurcations, multiperiodic oscillations, mixed-mode
oscillations, and chaos. Conversely, with self- and parametric drag forces, the system
displays reverse periodic bifurcations, periodic bubbling oscillations, antimonotonicity,
transient chaos, and chaos. Poincar´e maps analyze the geometric structure of chaotic
attractors, revealing a strong influence of dimensionless drag parameters. These
parameters can be manipulated to control or eliminate chaos. Furthermore, the system
exhibits multistability, with coexisting attractors. Beyond its application in protecting
infrastructure from wind damage, this research can contribute to ecological balance by
improving our understanding of tree wind resistance.

Design and Performance Analysis of Windings Considering High Frequency Loss and Connection Mode of a Starter Generator

The starter generator is the key component of the aircraft’s starter generation system. A high power density, efficiency, and reliability are essential for an aircraft’s starter generator. The configuration of the windings is closely related to the performance of the starter generator. In this paper, the winding performance analysis and design are studied. Considering the skin effect, circulation effect, and proximity effect, a calculation model of winding loss under high-frequency operation is established. The motor performance under different winding connections is compared. Through a comprehensive comparison of starting performance, generation loss, and process performance differences, the optimum configuration of windings is identified. The performance of the starter generator including winding resistance, current, and no-load loss was tested on the prototype platform to verify the rationality and correctness of the analysis and design methods.

Robust deadbeat predictive current control for unipolar sinusoidal excited SRM with multi-parameter mismatch compensation

In the control of unipolar sinusoidal excited switched reluctance motors (SRMs), deadbeat predictive current controllers (DPCCs) have gained attention for their enhanced dynamic performance. However, periodic disturbances caused by mismatches between the predictive model’s nominal and actual system parameters degrade the control performance of SRMs. To address this issue, a robust DPCC with multi-parameter compensation is proposed to improve dq0-axes current control performance. By analyzing the impact of parameter mismatches, a Kalman filter (KF) is developed to compensate for inductance coefficient mismatches, mitigating periodic disturbances. Additionally, a disturbance estimator with measurement noise suppression is integrated into the DPCC for both state and disturbance estimation to handle residual uncertainties, including winding resistance mismatches, magnetic saturation, and unmodeled dynamics. Compared simulation and experimental results validate the effectiveness of the proposed robust DPCC.

Progress on Single-Feed Quality Wideband Linear Wire Array

This paper presents the latest developments regarding the single-feed Quality Wideband Linear (QWL) wire array antenna, known for its broadband and high-gain electromagnetic characteristics and robust design. A systematic review of recent advances in relation to the QWL antenna is provided, covering its driven element, director, reflector, low common-mode current interference connector, and array series-feed configuration. For the first time, an analytical expression and a quick design formula for the input impedance of the QWL antenna’s driven element, the linear Wideband High-gain Electromagnetic Structure (WHEMS) antenna, are presented. Theoretical analysis demonstrates the potential for broadband performance using the WHEMS antenna. The rugged design of the QWL array antenna offers engineering advantages such as simple feeding, low wind resistance, a lightweight construction, low cost, and structural robustness. The QWL antenna has already found applications in various industrial sectors, with potential for broader use in the future, contributing to further advancements in antenna technology.

Experimental investigations on the influence of bridge deck gratings on the aerodynamic stability of the long-span suspension footbridge with a streamlined double-side box girder

In the complex wind environment of canyon regions, different kinds of bridge deck gratings (BDGs) are often used as novel aerodynamic countermeasures to improve the wind-resistance performance of long-span suspension footbridges. However, how to design reasonable BDGs to effectively improve the aerodynamic stability of long-span suspension footbridges is still an urgent problem to be solved, and there is no literature reporting on it. Therefore, in this study, according to a long-span suspension footbridge with a streamlined double-side box girder (SDSBG) and BDGs, the section models with different percentages of opening (β) and layouts of BDGs were made, and then the force- and vibration-measured tests were performed to study the influence of the layouts and β of BDGs on the aerostatic and flutter stability. Furthermore, the influence mechanism of BDGs on the flutter stability was investigated, and the optimal β and layouts of BDGs were also proposed. So, it is found that: when 0% ≤ β ≤ 22% (especially β = 11%), BDGs are unfavorable to the aerodynamic stability; when β ≥ 44%, the aerodynamic stability can be significantly improved by using BDGs; moreover, the layouts of Cases O (β reaches the maximum) and S (two strips of BDGs installed along the longitudinal direction) are more beneficial to the aerodynamic stability. Therefore, the optimal β and layouts of BDGs beneficial to the aerodynamic stability are β ≥ 44% and the layouts of Cases O and S, respectively, and the studies in this manuscript can provide a meaningful reference for the wind resistance design of long-span suspension footbridges in the future.

Highly efficient coke dust suppressant with anti-freezing capabilities

Stockpiled coke is prone to wind-blowing emissions, leading to economic losses and environmental pollution which imposes severe threats to human health. While various polysaccharide-based dust suppressants have been explored to resolve this issue, they often suffer from ineffective control of wettability, poor coverage, and suppression effect in extreme weather conditions, and require additional use of cross-linking agents and surfactants due to their weak interaction with coke. Herein, we present coke dust suppressants comprising polyethyleneimine (PEI), starch, and glycerol to address these shortcomings. Our detailed investigations show that the low toxicity, cationic polymer (PEI) electrostatically interacts with the coke, increasing the wettability and promoting aggregation. Moreover, PEI hydrogen-bonds with starch to form a stable film and enhances the water-retention capability. Furthermore, the addition of glycerol lowers the freezing point to −13 °C, preventing coke loss caused by freezing during transportation and energy loss associated with dismantling the frozen coke. Wind erosion tests and bomb calorimeter results reveal that the coke dust suppressant exhibits superior wind resistance and does not interfere with the coke combustion.

Strengthening flat-die friction self-pierce riveting joints via manipulating stir zone geometry by tailored rivet structures

Achieving high-strength joints with flat surfaces is of significant importance for reducing wind resistance and enhancing aesthetic appeal. In this study, a novel flat-die friction self-piercing riveting (flat-die F-SPR) process is proposed. The rivet flaring without die guidance was achieved through the sophisticated design of rivet structures. Three types of rivets with different internal structures were designed to manipulate the base material flow and microstructure evolution during the joining process. Based on the method of emergency stop, the load-stroke curves, evolutions of macroscopic morphology, and microstructure of the joints made with different rivets were investigated. A novel mechanism for solid-state bonding of joints was proposed to elucidate the generation and evolution of fine grain regions. The results indicate when downward pressure is applied to the material inside the rivet cavity, a central stirring zone appears. By using a rivet with an annular boss structure, the base material flows continuously into the stirring zone and piled up in the rivet cavity, forming a unique conical-shaped fine grain zone. Finally, a comprehensive assessment of the strength of different types of joints and the transition of the fracture modes were conducted based on different lower sheet thicknesses. The joints of Rivet_B and Rivet_C demonstrate 11.1% and 6.9% strength enhancement compared with the joint of Rivet_A, respectively. Two strategies for enhancing the strength of solid-state bonding are proposed by analyzing the joint strengthening mechanism, which offers insights for the optimizations of rivet structures.

A Novel Piezoelectric Nonwoven Fabric for Recoverable High-Efficiency Filters.

Serious haze pollution, mainly caused by fine and ultrafine particulate matters (PMs) and aerosols, poses a significant threat to the public health, especially when the aerodynamic diameter is less than 2.5 μm. Electrostatic capture techniques, such as polymer electret filters and kinetic plasma processes, are widely used instead of mechanical filtration with high removal efficiency and low wind resistance (pressure drop). However, the inability to recharge, coupled with the generation of ozone byproducts, makes it challenging to meet the requirements for both recoverability and highly efficient filtration. Here, we propose an electrostatic filter as an alternative to conventional polymer electrets, aiming to achieve an ultrahigh removal efficiency, long-term performance stability, and reusability. Piezoelectric LiNbO3 (LN) particles are integrated into the polypropylene (PP) matrix through the melt-blown strategy to fabricate the LN/PP nonwoven fabric. Benefiting from the employment of piezoelectric LN particles, the LN/PP nonwovens exhibit an ultrahigh removal efficiency of 99.9% for PM0.3 to PM10. The airflow facilitates the sustained regeneration of piezoelectric charges on the surface of LN/PP nonwovens, thereby maintaining a removal efficiency of approximately 95% for continuous filtration over 11 days. Even after eight cycles of washing, the removal efficiency of the LN/PP nonwovens remains at nearly 90%, demonstrating the excellent reusability. Our proposed strategy offers an ingenious combination of high-efficiency and recoverability for filters, holding great promise for reducing plastic pollution.

Structural health detection and wind resistance safety assessment of ancient dwellings based on laser point cloud

To address the inefficiencies of traditional detection methods and the loss of size information in finite element models for the health and safety evaluation of ancient buildings, this paper proposes a deformation detection method for ancient residential structures based on laser point clouds, and a wind resistance safety evaluation method based on finite element models. First, a three-dimensional (3D) laser scanner is used to collect and process data for the target building, resulting in a high-precision 3D point-cloud model of the ancient structure. Second, cross-sectional point clouds are obtained by cutting and projecting the beam and column structure point clouds. The cross-sectional information is then derived by fitting the cross-sectional point cloud with an oval curve. Using the calculation method for the deformation index, the deflection and inclination rates are calculated from the center-point coordinates of the fitted oval curve to evaluate the health status of the ancient residential structure. Finally, according to the finite element analysis method and the current situation model of ancient buildings constructed using laser point clouds, the structural deformation and damage to ancient dwellings under typhoon conditions are evaluated, taking typhoons, a common natural disaster in the region, as an example. The experimental results show that the structural health-detection indices, such as deflection and inclination rates of ancient dwellings, comply with code requirements. In the current state, the structures of ancient dwellings are damaged when subjected to typhoon forces of 0.7 kN/m2 and above. This method provides an accurate and effective mean to carry out structural health detection and wind resistance safety assessments of ancient residential buildings, offering a reliable basis for the protection of ancient buildings.

Dynamic characteristics of bridges with short pylons and outwardly inclined cable planes

This study developed a cable-stayed bridge characterised by short pylons and outwardly inclined cable planes. The dynamic characteristics of this bridge were investigated using the Lanczos eigenvalue and finite element methods. The first ten mode shapes and frequencies were analysed to this end. The influences of key parameters, such as the inclination angle of the pylons and the height and stiffness of the cable–pylon anchorage, on the dynamic characteristics of the bridge were examined. The results showed that the transverse bending modes of the main girder occurred first, while modes related to pylons appeared later. The torsional vibrational modes appeared in the 10th order, indicating the bridge had suitable wind resistance. Further, the outwardly inclined cable planes enhanced the lateral seismic resistance of the bridge. Increasing the rigidities of the cable–pylon anchorage and main girder can improve the dynamic characteristics of the bridge. This is accomplished by reducing the height of the cable–pylon anchorage and adding auxiliary piers.

Nonlinear Dynamics Induced by Coil Heat in the PMDC Motor and Control

In this paper, the interesting dynamics of chaos induced by the effect of the variation of internal average heat during operation in the DC motor control by the full bridge drive are analyzed. By using simple powerful tools of analyzing nonlinear dynamical systems like phase portraits, time traces and frequency spectrum in the MATLAB-SIMULINK environment, we showed that under certain conditions, the PMDC motor develops different behaviors so as periodic limited, and chaotic attractors, when the motor drive different form of external load torque and the windings resistance variation. This paper presents the first studies on the variation of the average heat of the motor and the amplitude of the triangular load torque to produce the strange phenomena like chaos as far as our knowledge go. A chaos control of the unstable regime is proposed to stabilize the PM DC motor in a desire regime. This contribution is very important in industry because some unexplained dynamical behaviors of the DC motor driven by a full bridge now can be avoided.

An efficient method for evaluating the wind resistance performance of high-vertical standing seam metal cladding systems

Uplift wind-induced responses and failure criteria of high-vertical standing seam metal cladding systems (SSMCSs) are of paramount importance for evaluating their wind resistance performance. This paper proposes an efficient evaluation method that combines a highly efficient finite element (FE) model for structural response analysis with reasonable failure criteria, based on experimental and numerical investigation. The FE model incorporating the developed equivalent spring model is established with the calibrated stiffness from tensile tests and validated through the wind uplift resistance experiments conducted on large-scale prototype structures. The recorded structural responses from the experiments validate the feasibility of the FE model in simulating the geometric and material nonlinearities of the systems. To evaluate the wind resistance performance, the failure criteria are developed based on the observed pullout mechanisms and failure modes from the experiments. These criteria take the relative deformation of standing webs and the pullout resistance strength of seam connections as critical parameters, and the relationship between them is calibrated through a series of tensile tests using a self-designed fixture. Tensile test results show notable variability in the pullout resistance strength of seam connections, with a mean value decreasing as the relative rotational angle of the standing webs increases. According to the developed failure criteria, the ultimate uplift pressures evaluated from the FE analysis exhibit minimal positive deviations of 5.3 % and 7.3 % from the experimental results for different failure modes, respectively. This highlights the effectiveness of the proposed method in evaluating the wind resistance performance of high-vertical SSMCSs.

Multi-Objective Route Planning Model for Ocean-Going Ships Based on Bidirectional A-Star Algorithm Considering Meteorological Risk and IMO Guidelines

In this study, a new route planning model is proposed to help ocean-going ships avoid dangerous weather conditions and ensure safe ship navigation. First, we integrate ocean-going ship vulnerability into the study of the influence of meteorological and oceanic factors on navigational risk. A multi-layer fuzzy comprehensive evaluation model for weather risk assessment is established. A multi-objective nonlinear route planning model is then constructed by comprehensively considering the challenges of fuel consumption, risk, and time during ship navigation. The International Maritime Organization (IMO) guidelines are highlighted as constraints in the calculations, and wind, wave, and calm water resistance to ships in the latest ITTC method is added to the fuel consumption and sailing time in the objective function. Finally, considering the large amount of data required for ocean voyages, the bidirectional A* algorithm is applied to solve the model and reduce the planning time. Furthermore, our model is applied to the case of an accident reported in the Singapore Maritime Investigation Report, and the results show that the model-planned route is very close to the original planned route using the Towing Manual, with an average fit of 98.22%, and the overall meteorological risk of the model-planned route is 11.19% smaller than the original route; our model can therefore be used to plan a safer route for the vessel. In addition, the importance of risk assessments and the IMO guidelines as well as the efficiency of the bidirectional A* algorithm were analyzed and discussed. The results show that the model effectively lowers the meteorological risk, is more efficient than the traditional route planning algorithm, and is 86.82% faster than the Dijkstra algorithm and 49.16% faster than the A* algorithm.

Biomechanics of human locomotion in the wind.

In laboratory settings, human locomotion encounters minimal opposition from air resistance. However, moving in nature often requires overcoming airflow. Here, the drag force exerted on the body by different headwind or tailwind speeds (between 0 and 15 m·s-1) was measured during walking at 1.5 m·s-1 and running at 4 m·s-1. To our knowledge, the biomechanical effect of drag in human locomotion has only been evaluated by simulations. Data were collected on eight male subjects using an instrumented treadmill placed in a wind tunnel. From the ground reaction forces, the drag and external work done to overcome wind resistance and to sustain the motion of the center of mass of the body were measured. Drag increased with wind speed: a 15 m·s-1 headwind exerted a drag of ∼60 N in walking and ∼50 N in running. The same tailwind exerted -55 N of drag in both gaits. At this wind speed, the work done to overcome the airflow represented ∼80% of the external work in walking and ∼50% in running. Furthermore, in the presence of fast wind speeds, subjects altered their drag area (CdA) by adapting their posture to limit the increase in air friction. Moving in the wind modified the ratio between positive and negative external work performed. The modifications observed when moving with a head- or tailwind have been compared with moving uphill or downhill. The present findings may have implications for optimizing aerodynamic performance in competitive running, whether in sprints or marathons.NEW & NOTEWORTHY This is the first study to assess the biomechanical adaptations to a wide range of wind speeds inside a wind tunnel. Humans increase their mechanical work and alter their drag area (CdA) by adapting their posture when walking and running against increasing head and tailwinds. The observed drag force applied to the subject is different between walking and running at similar headwind speeds.

Aerodynamic Optimization Design of a Supergravity Centrifuge: A Low-Resistance Strategy

Wind resistance optimization is crucial for enhancing the rotational speed of supergravity centrifuges. We conducted a study using computational fluid dynamics on the Centrifugal Hypergravity and Interdisciplinary Experiment Facility (CHIEF) under construction at Zhejiang University and validated it experimentally using a ZJU400gt centrifuge. Our findings indicate significant reductions in wind resistance through structural modifications of the CHIEF. Reducing the outer radius from 4650 to 4150 mm decreased wind resistance by 16%, primarily due to reduced effective viscosity in the wake region’s gases. More substantial reductions were achieved by lowering the height of the outer wall from 2200 to 1400 mm, which cut wind resistance by 25%. This height reduction suppressed vortex shedding and Kármán vortex street development via the Venturi effect. Adjustments to the roughness height of wall surfaces further decreased wind resistance, with minimal impact from arm roughness. A critical roughness height was identified, below which no further reductions in wind resistance could be attained. Notably, using disc-shaped arms reduced wind resistance by approximately 73% because of their minimal pressure–resistance components and predominant frictional resistance, highlighting their potential in future high-speed centrifuge designs.

The passive optimization mechanism of winter thermal performance in commercial complex based on coupled multi-spatial parameters

In cold regions, public buildings often suffer from suboptimal thermal performance due to cold air intrusion. This study explores the synergistic impact of multiple spatial parameters on winter thermal environments to discover the passive optimization potential in commercial complexes. Airflow analysis covers the entire connected space from the entrance to the large atrium, integrating the collective effects of all critical spatial parameters. Based on 4500 Computational Fluid Dynamics (CFD) simulation, the study establishes how these parameters influence wind resistance and thermal comfort. Key findings reveal that the “Atrium-plan Ratio,” “Transitional Space-width,” and “Atrium-height,” are most impactful on wind resistance, contributing over 53 % collectively. For thermal comfort, “Atrium-volume,” “Atrium-section Form,” and “Atrium-height,” are most significant, with a combined weight exceeding 57 %. As wind speed increases, the effect of single parameters gradually diminishes, highlighting the synergistic effect of spatial combinations. A case study demonstrates an 80.5 % improvement in thermal performance score following optimization, underscoring the potential for low-carbon, high-efficiency design in commercial complexes.

Equivalent static wind load based on displacement mode and load combination for high‐rise buildings

AbstractUnder the action of the fluctuating wind load, the low frequency part produces background response to the structures, while the high frequency part produces resonance response to the structures. In structural design, equivalent static wind load is usually used to equate the fluctuating wind load. Although there are various methods of evaluating the equivalent static wind load, they did not consider the correlation between modal responses or considered them insufficiently. Therefore, in this paper, the correlation between modal response is considered to evaluate the equivalent static wind load, the displacement response is decomposed by proper orthogonal decomposition (POD) method, the correlation between modal displacement is removed, the equivalent static wind load is expressed in the form of displacement mode, and then the correlation between modal response is fully considered in the extreme value combination. This paper combines the equivalent static wind loads in order to make the wind resistance design more reasonable for high‐rise buildings. First, the formulas of equivalent static wind loads expressed by displacement modes of background and resonant response are deduced based on modal decomposition and POD method. Second, the combination formulas of square‐root‐of‐sum‐square (SRSS) and complete‐quadratic‐combination (CQC) rules for the equivalent static wind loads considering the mean wind loads are proposed. Both the linear combination formula of SRSS for the equivalent static wind load and the weighting factor expressions of background and resonance equivalent static wind load are given. Third, the accuracy and validity of the formulas of equivalent static wind load are verified by a wind tunnel pressure test of a high‐rise building. Finally, the simplified combination coefficient formulas for the equivalent static wind loads are proposed, and the combination of the high‐rise building base's fluctuating equivalent static wind loads of along‐wind direction, across‐wind direction, and torsional direction is analyzed.

Preparation of an environment-friendly microbial limestone dust suppressant and its dust suppression mechanism.

The development of an efficient and environmentally friendly dust suppressant is crucial to address the issue of dust pollution in limestone mines. Leveraging the synergistic microbial-induced calcium carbonate precipitation (MICP) technology involving NaHCO3 and dodecyl glucoside (APG), the optimal ratio of the dust suppressant was determined through single-factor and response surface tests. The dust suppression efficacy and mechanisms were analyzed through performance testing and microscopic imaging techniques, indicating that the optimal ratio of the new microbial dust suppressant was 20% mineralized bacteria cultured for 72h, 0.647molL-1 cementing solution, 3.142% NaHCO3, and 0.149% APG. Under these conditions, the yield of calcium carbonate increased by 24.89% as compared to when no NaHCO3 was added. The dust suppressant demonstrated excellent wind, moisture, and rain resistance, as well as curing ability. More calcite was formed in the dust samples after treatment, and the stable form of the dust suppressant contributed to consolidating the limestone dust into a cohesive mass. These findings indicate that the synergistic effect of NaHCO3 and APG significantly enhanced the dust suppression capabilities of the designed microbial dust suppressant.