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We study the near-inertial response of the salinity-stratified north Bay of Bengal to monsoonal wind forcing using 6 years of hourly observations from four moorings. The mean annual energy input from surface winds to near-inertial mixed layer currents is 10–20 kJ m−2, occurring mainly in distinct synoptic "events" from April–September. A total of fifteen events are analyzed: Seven when the ocean is capped by a thin layer of low-salinity river water (fresh) and eight when it is not (salty). The average near-inertial energy input from winds is 40% higher in the fresh cases than in the salty cases. During the fresh events, 1) mixed layer near-inertial motions decay about two times faster and 2) near-inertial kinetic energy below the mixed layer is reduced by at least a factor of three relative to the salty cases. The near-inertial horizontal wavelength was measured for one fresh and one salty event; the fresh was about three times shorter initially. A linear model of near-inertial wave propagation tuned to these data reproduces 2); the thin (10 m) mixed layers during the fresh events excite high modes, which propagate more slowly than the low modes excited by the thicker (40 m) mixed layers in the salty events. The model does not reproduce 1); the rapid decay of the mixed layer inertial motions in the fresh events is not explained by the linear wave propagation at the resolved scales; a different and currently unknown set of processes is likely responsible. [ABSTRACT FROM AUTHOR]

Due to the widespread penetration of wind energy, large-capacity wind turbines (WTs) are becoming more conspicuous. In this paper, a linear control-oriented large-capacity wind turbine (WT) model is redesigned based on the 15 MW WT in openFAST. Compared with the original model, the redesigned model is more efficient and conducive to the design of linear controllers. To verify the validity of the redesigned WT model, we design a distributed control scheme with deloading operation of the wind farm (WF) to fairly share the load. Simulations are performed to verify the effectiveness of the application in the WF. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the impacts of roof ridges and semi-cylindrical tiles on the wind loading on traditional single-eave hip roofs. To the best of the authors' knowledge, the semi-cylindrical tiles have been considered in the simulation of ancient Chinese architecture for the first time. Several roof models with various ridges and semi-cylindrical tiles are simulated by solving the Reynolds-averaged Navier-Stokes equations (RANS) using the computational fluid dynamics (CFD) technique. The results reveal that the addition of roof ridges and semi-cylindrical tiles has a considerable structural protection effect, which can significantly reduce the suctions, as well as the turbulence fluctuation, on both the windward and leeward sides: the average of negative mean wind pressure coefficients is reduced by 33% on the leeward surface, and approximately 48% on the windward surface one. When the number of protruding ridges and semi-cylindrical tiles increases (decreasing the diameter of them by 40%), the average of area mean wind pressure coefficient for all the wind directions decreases by about 30% on the windward side and about 50% on the leeward side. The average of maximum spatial wind pressure coefficient decreases by about 25% on the windward side and about 40% on the leeward side. [ABSTRACT FROM AUTHOR]

This paper pertains to the reliability analysis of transmission tower foundations under variable wind loads. The reliability analysis of the anchor foundation, frequently employed for transmission towers due to their huge uplift capacity at shallow depth, is presented using a systematic probabilistic approach. The paper presents the design of an anchor foundation for a typical transmission tower based on loads obtained by applying lateral wind velocity on the tower. The Multivariate Adaptive Regression Splines (MARS) surrogate model is first developed to construct a deterministic prediction model for the anchor uplift capacity. The developed model is further used in the reliability analysis of the anchor foundation considering variabilities in the soil properties and the uplift load, and the results of the probabilistic analysis are reported in the paper. The results indicate the importance of incorporating variability in design variables for the proper safety of the structure. Soil cohesion is found to be the most sensitive parameter in the uplift capacity of the tower foundation. The comparison of the deterministic factor of safety and failure probability of the foundation brings out the importance of the reliability-based design methodology. [ABSTRACT FROM AUTHOR]

Summary: As one of major construction facilities, the safety concern about elevator outer‐attached to slender high‐rise buildings during construction needs to be seriously addressed. To specifically identify the risk of such slender building–elevator systems in extreme tornado wind field, a safety assessment strategy using the critical velocity envelope is systematically developed. To overcome the difficulties in modeling such building–elevator system, a modified generalized flexural‐shear model developed previously was employed to reach an efficient estimate on the response of a case high‐rise building under simulated tornado wind excitations. To account for the effect of the flexibility of high‐rise building on the response of its attached construction elevator, the response of the elevator was obtained by finite element analysis with applied wind forces, as well as the displacement excitations at its supports with the building. To simulate the typical failure modes of elevator in all states, some critical reference velocity‐based envelopes were generated for the safety assessment where the factors of wind velocity, wind direction, and cage level are systematically addressed. The safety envelopes of the building–elevator system were proved to be instinctively efficient for the assessment of its wind resistance under various scenarios. [ABSTRACT FROM AUTHOR]

In this work, a degenerate diffusion state is identified for common L12 intermetallics in well-defined five-frequency model (FFM) and anti-site bridge model (ASB). The relative energy barrier $ {{{E_4}} / {E_B^{\beta \to \alpha }}} $ E 4 / E B β → α ( $ {E_4} $ E 4 in FFM and $ E_B^{\beta \to \alpha } $ E B β → α in ASB) of the degenerate state serves as a decomposer which not only bifurcates the degenerate pathways, but also determines the most probable diffusion model. The diffusion coefficients obtained from the most probable diffusion model coincides the experimental value. We find the proposed decomposer complies with the Onsager phenomenological theory and atomistic correlation understanding, and is also supported by the relative work $ {{{W_{FFM}}} / {{W_{ASB}}}} $ W FFM / W ASB done by electronic wind force. [ABSTRACT FROM AUTHOR]

The existence of water-filled barriers alters the cross-sectional shape of the main girder, which may lead to vortex-induced vibrations (VIVs) in suspension bridges. However, the mechanism and occurrence conditions of VIVs in the main girder that is affected by water-filled barriers are still unclear. To this end, this study investigates the effect of water-filled barriers on the VIV performance of suspension bridges. The evolution of the vortex structure during one VIV cycle and the corresponding pressure variations, including the average and fluctuating values on the surface, were analyzed. Additionally, the spatiotemporal distribution of the surface pressure was studied using proper orthogonal decomposition (POD). The results show that VIV occurs in the main girder when the height of the water-filled barriers exceeds a threshold value of 0.317. Moreover, a significant negative pressure vortex occurred when the barriers were installed. The vortex underwent the following distinct phases in one VIV cycle: generation, separation, reattachment, and shedding. However, the negative pressure vortex behind the barrier did not vary substantially when the water-filled barriers were installed without VIV. Additionally, the average pressure on the surface of the main girder remained constant regardless of the occurrence of VIVs. In the presence of VIVs, the pressure fluctuations became much more pronounced and were mainly concentrated on the top surface and leading edge of the main girder. Additionally, the dominant modes of the pressure variations correlated with the evolution of the vortices and pressure distribution. [ABSTRACT FROM AUTHOR]

Large oil and gas storage tanks serve as crucial industrial energy infrastructures, which are usually thin-walled steel structures with large volumes and light weights, and they are sensitive to wind loads. Under the influence of strong winds or typhoons, large oil and gas storage tanks may suffer wind-induced damage, resulting in the leakage of gas or liquid inside the tanks, posing hazards to the ecological environment and public safety. Therefore, it is of great theoretical and engineering significance to research the wind resistance of large oil and gas storage tanks. This paper provides a comprehensive review of key issues in wind resistance for large oil and gas storage tanks, including characteristics of flow around circular cylinders, wind effects on structures with circular cross-sections, near-surface wind field characteristics, wind effects on large oil and gas storage tanks, wind-induced interference effects, structural dynamic characteristics, wind loads and wind-induced response calculations, multiple load effects, and wind-induced vibration control. The deficiencies of current research are summarized. The prospects for research on the design theory and safety assurance of large oil and gas storage tanks are presented through various methods, including field measurements of near-surface wind fields and wind effects, wind tunnel tests utilizing aeroelastic models, numerical simulations involving fluid–solid coupling, theoretical analysis, and machine learning. [ABSTRACT FROM AUTHOR]

Guanabara Bay, located in the Metropolitan Region of Rio de Janeiro, one of the largest urban coastal areas in the Southern Hemisphere, is subject to intense maritime traffic due to the presence of several ports. These facilities are affected by sea level fluctuations, influenced by atmospheric and astronomical forces, which motivates synoptic and climatological analysis, including meteorological and astronomical tidal phenomena. This study aimed to assess the evolution of tidal components and the relative mean sea level (MSL) between 1990 and 2021, as well as the atmospheric influence on extreme meteorological tide events, in which the MSL exceeded ±2 and ±3 (±29.98 and ±44.97 cm) standard deviations. The results have shown that, albeit small, the main tidal components (M2$$ {M}_2 $$, S2$$ {S}_2 $$, O1$$ {O}_1 $$, M4$$ {M}_4 $$, Q1$$ {Q}_1 $$, K1$$ {K}_1 $$, K2$$ {K}_2 $$ and N2$$ {N}_2 $$) indicated positive trends in the increase of amplitude and phase, despite the small quantities. For the relative MSL, an increase of 0.30 cm·year−1 was observed in agreement with estimates from global series from satellite altimeters and climate model predictions. Pressure and wind field analyses led to the identification of seasonal variability and the pattern of evolution of atmospheric systems associated with extreme events. In the case of positive surges, very intense winds from the SW, extending along the S/SE Brazilian coast, are caused by the presence of a high‐pressure centre over the continent and low‐pressure centres over the ocean, leading to water piling up. In turn, negative surges are caused by the presence of an anticyclone over the ocean, generating NE winds parallel to the coast of Rio de Janeiro, inducing Ekman transport and lowering the sea level. Therefore, the extreme sea level events in the Guanabara Bay are not triggered by local forces, but rather depend on the temporal persistence and direction of winds along the S/SE Brazilian coast. [ABSTRACT FROM AUTHOR]

Summary: This study investigates the impact of different positions of two limbs on the structural response of a rectangular building model to wind forces. The building's geometry assumes Z and + shapes based on specific limb configurations. Computational fluid dynamics (CFD) simulations are performed to quantify wind‐induced pressures, resulting in wind force coefficients. These coefficients are used to develop predictive machine learning models through Gene Expression Programming, Group Method of Data Handling‐combinatorial (GMDH‐Combi), Model Tree, and Artificial Neural Network (ANN) techniques. The ANN analysis explores various combinations of training algorithms, adaptation functions, activation functions, and performance functions to enhance model accuracy. Among these, the Levenberg–Marquardt (LM) with gradient descent with momentum (GDM) adaptation function and sigmoid activation function exhibit superior performance with high R‐squared values. These predictive models are then employed for a comprehensive comparative assessment of the maximum wind force coefficient (CF, max) concerning different limb positions and angles of attack (AOA). For CF, max vs Limb position, variations of limb position are examined for most critical cases of AOA. Similarly, the study of CF, max vs AOA involves an exhaustive investigation into the variation of AOA for the building with the worst limb position. The analysis reveals that changes in AOA have a more pronounced effect on CF, max compared to alterations in limb position. Interestingly, within the AOA range of 1.5 to 2.5, the CF, max consistently reaches a minimum across all models. However, the relationship between CF, max and the critical structural parameter 'S' (representing limb position) remains less conclusive for the most significant AOAs. [ABSTRACT FROM AUTHOR]

Interplanetary coronal mass ejections (ICMEs) and the driven geomagnetic storms have a profound influence on the ionosphere, potentially leading to a degradation in positioning performance. In this study, we made a comprehensive analysis of the entire process of the impact of a typical ICME and its driven geomagnetic storm on the low-latitude ionosphere during March 13-14, 2022 (π-day storm) and the positioning performance of Global Navigation Satellite System (GNSS). During the passage of the ICME event, significant ionospheric scintillation, and TEC (total electron content) disturbances were observed in the low-latitude Hong Kong region. The ICME sheath region intensively compressed the magnetosphere via solar wind dynamic pressure enhancement and subsequently drove the storm main phase. It is found that both the magnetospheric compression that formed the storm initial phase and the storm main phase caused ionospheric scintillation. In comparison, the intensity of the ionospheric scintillation caused by the intense magnetospheric compression just before the storm main phase is even more pronounced. We also analyzed the impact of storms on standard point positioning (SPP), precise point positioning (PPP) and real-time kinematic (RTK) techniques. The positioning accuracies of single-frequency SPP and PPP experienced the most severe decline, and there was a noticeable increase in the initialization time for dual-frequency static PPP and RTK during the event. RTK demonstrated a shorter convergence time and higher accuracy during this event, but it was limited to short-baseline RTK (<30 km). [ABSTRACT FROM AUTHOR]

Flexible skins that can be laminated on curved surfaces are a desired form for wind pressure measurement. Sensors for such applications need to detect both negative and positive wind pressure with ultrahigh pressure resolution over a wide range up to 600 kPa, whereas existing flexible sensors are unsatisfactory to such demands. Here, we report a flexible skin containing two iontronic pressure sensors for negative pressure and positive pressure sensing, respectively, and show the potential of the skin for pressure measurement in room temperature wind tunnels. We control the contact state of iontronic interface of a sensor to introduce a pre-pressure that enables negative pressure sensing, exhibiting a pressure resolution of −20 Pa (0.025%) within a broad pressure regime (from −100 kPa to −10 Pa). The other sensor for positive pressure sensing exhibits a pressure-resolution of 100 Pa (0.025%) over 600 kPa, in addition to a wide frequency bandwidth up to 400 Hz. The skin with the two types of sensors can be attached on curved surfaces of wing surface for pressure measurement at various free stream velocities and angles of attack. This study provides a promising technology of using flexible skins for pressure measurement in aviation applications. Flexible skins are desired for wind pressure measurement on curved surfaces. Here, the authors report a flexible skin using two iontronic pressure sensors for negative pressure and positive pressure sensing, respectively, and demonstrate its application to pressure measurements in room temperature wind tunnels. [ABSTRACT FROM AUTHOR]

Tropical and extra-tropical storms generate extreme waves, impacting both nearby and remote regions through swell propagation. Despite their devastating effects in tropical areas, the contribution of tropical cyclones (TCs) to global wave-induced coastal risk remains unknown. Here, we enable a quantitative assessment of TC's role in extreme waves approaching global coastlines, by designing twin oceanic wave simulations with and without realistic TC wind forcing. We find that TCs substantially contribute to extreme breaking heights in tropical regions (35-50% on average), reaching 100% in high-density TC areas like the North Pacific. TCs also impact remote TC-free regions, such as the equatorial Pacific experiencing in average 30% of its extreme wave events due to TCs. Interannual variability amplifies TC-induced wave hazards, notably during El Niño in the Central Pacific, and La Niña in the South China Sea, Caribbean Arc, and South Indian Ocean coastlines. This research offers critical insights for global risk management and preparedness. This paper shows that tropical cyclones contribute between 40% and 100% of the extreme wave events approaching coastlines in basins prone to tropical cyclone activity, while they can also impact remote areas via swell propagation across the ocean. [ABSTRACT FROM AUTHOR]

In winter, the Kuroshio Current intrudes onto the continental shelf in the East China Sea with a cyclonic branch occasionally veering northeast of the Taiwan Strait. The dynamic process and mechanism by which the southward Kuroshio branch enters the Taiwan Strait is investigated using a numerical model. Decomposition of the flow field and sea surface height (SSH) using the empirical orthogonal function (EOF) isolates the first mode of the southward flow and the east‐westward SSH slope, showing that the time series is closely related to wind strength. The southward Kuroshio branch is mainly controlled by geostrophic and Ekman effects. When northeasterly winds are weak, the elevated SSH on the eastern side, caused by the Kuroshio, generates a northward geostrophic current. This northward current overwhelms the Ekman current and triggers the Taiwan Warm Current. Conversely, when northeasterly winds are strong, an elevated SSH on the western side generates a southward geostrophic current. A theoretical equation is devised, which accounts for Ekman layer depth related to wind strength and geostrophic adjustments by the Ekman effect. This equation explains why the Kuroshio branch flows into the northern Taiwan Strait and why there is a counter‐wind current (i.e., Taiwan Warm Current) during winter. Furthermore, we propose a novel perspective that suggests the alongshore current and cross‐shore sea level in the Taiwan Strait are determined by the wind‐driven current and geostrophic adjustment, which are generated by the competition or cooperation between the wind and the alongshore pressure gradient caused by the Kuroshio. [ABSTRACT FROM AUTHOR]

The paper presents the reconstruction of sea levels in the North Sea and Baltic Sea using Kalman filter approach. Based on the statistical characteristics of one year of daily maps of sea level from the Geesthacht COAstal model SysTem (GCOAST) and daily data at tide gauges along the coastline of two basins, the method can reconstruct effectively and accurately the multidecadal sea level anomalies. The high accuracy reconstruction data were then used to investigate the interannual variability in both basins and to estimate the difference between outflows and inflows (net flux) through the Danish Straits. The highest mean, standard deviation, and extreme values of sea level anomalies appear in winter and are well reproduced in different regions, such as the German Bight, the Southern North Sea, the Bothnian Bay, the Gulfs of Finland and Riga. The sea level variability is highly correlated with the mean sea level pressure and the zonal wind, particularly in the German Bight and in the winter months. The contributions of river runoff and net precipitation on the net flux are significant in the spring. The local wind has a greater influence on the net flux than the remote drivers. [ABSTRACT FROM AUTHOR]

There have historically been, and still are, problems with water intrusion into new external walls of prefabricated concrete sandwich elements in Sweden to a varying extent. The aim of this study was to obtain documented knowledge and data on driving rain resistance, to provide a basis for improvements and calculations in a common kind of concrete sandwich system with façade components and sealing products. The study included inspections and air pressure difference measurement of façades in the field and driving rain resistance testing of experimental set-ups in a laboratory. Inspection showed that vertical joints between the concrete elements were often significantly too narrow and, at the same time, adhesion loosening of building mastic in these joints was common. TDV-tubes were often incorrectly placed or had a bad incline. Field measurements indicate no pressure equalization, which is also confirmed by lab measurements. Lab results indicated inward leakage at window-wall interface, even without wind pressure, through the TDV-tubes despite a sharp incline, in element joints with a new kind of application of pre-compressed joint sealing tape. The largest leakage flows were of 0.4% of the vertical water flow across a unit width of the façade at the given height. [ABSTRACT FROM AUTHOR]

The safety of wind power equipment under dynamic load is one of the key factors to ensure sustainable energy recovery. In order to effectively improve the reliability of tower structure, the damage identification of flange bolt fracture based on strain mode was studied, and the vibration control and optimization scheme was proposed and verified. The dynamic response of the tower to wind load was calculated using the theory of Davenport spectrum. Combined with computational fluid dynamics, the dynamic load change law of the tower was obtained. Based on ANSYS Workbench, the modal simulation and analysis of the tower were carried out. Under different bolt damage conditions, the distribution characteristics of the strain modal shape of the tower in the axial and radial directions were obtained. The vibration damper was applied to the inside of the tower, and the vibration and stress at different positions under wind load were compared and analyzed to verify the specific vibration reduction and optimization effect. The results show that the strain modal shape of the tower cylinder has a significant peak at the damage site, and the peak height is positively correlated with the damage degree, indicating that the strain modal shape is highly sensitive to the damage. In addition, the vibration and maximum stress of the flange and top position of the tower have been effectively reduced by the shock absorber. The average amplitude of tower top can be reduced by 22.5 %, and the peak stress at the bottom flange position can be reduced by about 38 %. [ABSTRACT FROM AUTHOR]

Wind from all directions Wind loads on membrane structures are not regulated by standards. The variety of shapes of the typically open and thus flow‐exposed surfaces on both sides cannot be captured using geometric variables in tables, as is common for typical building forms in Eurocode EN 1991‐1‐4. The recommended individual wind tunnel tests are only feasible for larger projects with the corresponding budgets and planning periods. Therefore, some recommendations for typical membrane roofs have been collected in the literature, and at the same time, computer‐based wind simulations have developed to the extent that they are now also offered in market‐standard FEM software packages. This paper aims to explain the accuracy and comparability of the various approaches using case studies. The paper presents the analysis of standard approaches, literature values, wind tunnel tests, and computer‐based methods with a comparison of calculation results and provides insights into the development of load assumptions in membrane construction. [ABSTRACT FROM AUTHOR]

Large‐span membrane roofs: wind loads and dynamic response It is state of the art to determine wind loads on large‐span lightweight roofs by means of appropriate wind tunnel tests. Simultaneous measurements of wind‐pressure time series on upside and downside of the roof allow calculation of time‐dependent wind load distributions over the roof which – as will be shown – are relevant for design purposes. These time‐dependent wind load distributions are also the basis for calculation of corresponding dynamic response of the roof (dynamic resonant loads caused by wind impact). It will be shown that consideration of different modal shapes may be important for design of large‐span lightweight roofs. Furthermore, it will be discussed that is not accurate to apply only one constant dynamic amplification factor for whole roof. Finally, it is described why numerical flow simulations (CFD=computational fluid dynamics) are (still) not appropriate to determine design wind loads and corresponding additional dynamic resonant loads for large‐span lightweight roofs adequately. [ABSTRACT FROM AUTHOR]

Wind resistance performance research on the influence of the exterior features of high-rise buildings is an essential part of structure design. In this paper, the wind resistance tests of three high-rise building models with different concavity shapes on the horizontal plane were investigated using the wind tunnel experiment. The CAARC (Commonwealth Advisory Aeronautical Research Council) standard high-rise model was adopted as the background model (BG model for short), and the other two comparison groups with different planar configurations were designed, one with concave corners around the building (T1 model) and the other with concavity in the middle of the long side of the building (T2 model). The distribution laws of the average wind pressure coefficients of the building facades and roofs under the whole wind azimuths were analyzed comprehensively. The results show that the external shape plays a certain role in wind pressure distribution. Among the three high-rise building models, the most unfavorable positive wind pressure coefficient on the facades occurs in the T2 model (a 4.7% increment compared with the BG model), while the most unfavorable negative wind pressure coefficient appears in the T1 model (a 25% increment compared with BG model). Furthermore, it is noted that the architectural appearance of the T1 model makes the flow field around the building more streamlined, reflecting more favorable wind-resistance performance, including a maximum reduction of 47.2% in the least stresses per unit area on the roof. The research in this paper can provide some references for the design of different exterior features of high-rise buildings. [ABSTRACT FROM AUTHOR]

Based on a new mathematical framework and large multi-year multi-mission data sets, we reconstruct electric currents and magnetic fields around the dayside magnetopause and their dependence on the incoming solar wind, IMF, and geodipole tilt. The model architecture builds on previously developed mathematical frameworks and includes two separate blocks: for the magnetosheath and for the adjacent outer magnetosphere. Accordingly, the model is developed in two stages: 1) reconstruction of a best-fit magnetopause and underlying dayside magnetosphere, based on a simple shielded configuration, and 2) derivation of the magnetosheath magnetic field, represented by a sum of toroidal and poloidal terms, each expanded into spherical harmonic series of angular coordinates and powers of normal distance from the boundary. The spacecraft database covers the period from 1995 through 2022 and is composed of data from Geotail, Cluster, Themis, and MMS, with the total number of 1-min averages about 3 M. The modeling reveals orderly patterns of the IMF draping around the magnetosphere and of the magnetopause currents, controlled by the IMF orientation, solar wind pressure, and the Earth's dipole tilt. The obtained results are discussed in terms of the magnetosheath flux pile-up and the dayside magnetosphere erosion during periods of northward or southward IMF, respectively. [ABSTRACT FROM AUTHOR]

The Rosetta spacecraft observed the temporal evolution of the ion populations within the ionosphere of comet 67P/Churyumov–Gerasimenko. A striking feature of the ion spectrum is represented by the so-called medium-energy ion peaks, which recurrently emerge from the low-energy ion background with their energy levels typically reaching 50 to 1000 eV before their energy gradually decreases, and they disappear from the measurements. These peaks are believed to be caused by space weather forcing, but there was no conclusive evidence until now. We investigated the characteristics of these ions, paying special attention to the connection between the solar wind dynamic pressure and the amount and energy of the medium-energy ions. Our findings reveal a strikingly accurate direct correlation between the dynamic pressure of the solar wind at the position of the comet and the amount of medium-energy ions measured by Rosetta. The ion energy also unquestionably reacts to the effects of solar wind pressure variation, but this parameter is strongly affected by the production rate and the distance from the nucleus as well. We explain these close correlations between cometary ion and solar wind characteristics using the well-founded assumption that certain boundary layers of the magnetosphere can move in and out under the influence of higher and lower solar wind pressure. [ABSTRACT FROM AUTHOR]

The vertically integrated zonal momentum balance of the Antarctic Circumpolar Current (ACC) is dominated by wind stress at the surface and topographic form stress (TFS) at the bottom. It has been argued that wind stress is transferred from the surface to the bottom by transient baroclinic eddies, via interfacial form stress, to establish the balance between wind stress and TFS. However, ocean models indicate TFS responds rapidly to changes in wind stress, suggesting that barotropic processes play a role in this balance. We investigate the dynamics governing the wind–TFS balance of the ACC and its response to wind using an idealized, wind- and buoyancy-driven channel model. We show that the balance is established and maintained at equilibrium by the barotropic dynamics. The balance results from the continuity of the flow, in which the Ekman transport at the surface, balanced by wind stress, is compensated by a return flow at depth, balanced by TFS. This leads to a match between wind stress and TFS which is independent of momentum stresses in the interior. Transient baroclinic eddies oppose the wind-driven isopycnal steepening via eddy buoyancy fluxes, which act to flatten the isopycnals. The eddy-driven isopycnal flattening corresponds to a reduction in the zonal geostrophic shear and thus a redistribution of the zonal momentum in the interior via eddy momentum stresses. The maintenance of the vertically integrated ACC momentum balance by the barotropic dynamics explains the fast response of the wind–TFS balance to changes in wind forcing. [ABSTRACT FROM AUTHOR]

In the present study, the principal objective is to investigate the role of multiple tuned mass damper (MTMD) to reduce aerodynamic effect of wind force on "V" plan-shaped high-rise buildings with the various internal limb angle. Distinct cases have been made by considering the angle between the limbs is 90° which is gradually increased from 90° to 150° with 15° regular interval and decreased from 90° to 40° with 10° regular interval maintaining same plan area and limb width subjected from 0° to 180° wind incidence angle with 30° regular interval. Computational fluid dynamics (CFD) is adopted to determine the aerodynamic coefficients by numerical simulation. A polynomial expression has been proposed to compute force, moment, and torsional coefficient along X, Y, and Z direction from the entire result for avoiding rigorous calculation. Dynamic wind time history in along and crosswind is obtained using maximum force coefficient. The dynamic response analysis such as peak displacement, acceleration is obtained for selected models with MTMD and effectiveness of MTMD is computed. Finally, the influence of MTMD and internal angle variation on the wind-induced response of "V" plan-shaped buildings have been observed to determine suitability of internal angle variation based on the numerical result. [ABSTRACT FROM AUTHOR]

Performance-based design optimization (PBDO) aims to design safe, resilient, and cost-effective structures. Methods used for PBDO have evolved by integrating numerical modeling, performance-based design principles, and optimization algorithms. The PBDO framework enables the design of structures with optimal performance and cost. This paper provides researchers with a comprehensive review of the rapidly growing field of PBDO. The evolution of PBDO methods is discussed with the goal of identifying the challenges that must be addressed in future studies. Knowledge gaps are brought to the forefront to emphasize the need for further investigation that expands on the application of PBDO in structural design. Various deterministic and probabilistic formulations for PBDO of structural systems under seismic and wind loading are reviewed. The formulations encompass one or more objective functions, including the upfront, life-cycle, and repair costs. Furthermore, the paper reviews retrofit design studies that have used PBDO methods. The high computational demand in performing PBDO is identified as the major challenge. Possible approaches to alleviate this and other challenges are discussed. [ABSTRACT FROM AUTHOR]

High-rise buildings are sensitive to multihazard loads from both short and long-term perspectives. Adding tuned mass dampers (TMDs) is a well-established method to improve the performance of tall buildings, but the cost-benefit of adding TMDs is still a research question to be tackled. To answer this question, a methodology for optimal simultaneous design of reinforced concrete components and TMDs in high-rise buildings is developed for the first time. A cost-benefit focused optimization problem is defined, adopting a monetary cost function that includes direct and indirect costs and the multihazard long-term repair costs. Design variables related to the primary structure and the dampers are selected, as well as a set of constraints. The shear wall rigidities and capacities are included by generating a database of moment-curvature relations, followed by a curve-fitting procedure. An efficient gradient-based algorithm is developed to solve these challenging problems. Using this algorithm, 35 problems are solved, considering three building heights and three metropolitan areas in Israel, with their specific hazard and cost inputs. The results show that for 40-story buildings, adding TMDs is not profitable. For 50-story buildings, this is profitable for Jerusalem, marginally profitable for Tel-Aviv and not practical for Haifa. For 60-story buildings, adding TMDs is profitable for all the locations, with the greatest benefit being detected for Jerusalem, and then for Tel-Aviv in second place. The results are explained by the different building heights, wind load magnitudes and surface selling prices. The framework is shown to be flexible and appropriate for a preliminary TMD profitability assessment. [ABSTRACT FROM AUTHOR]

The Antarctic Bottom Water (AABW) exported from the Weddell Sea has experienced warming and contraction in the past 30 yrs. Superposed on this decadal trend is substantial annual and interannual variability in the volume and properties of Weddell‐sourced AABW. Several mechanisms have been suggested to explain these variations, many of which highlight a role of wind stress, but the comparative importance and possible simultaneity of the different mechanisms remains unclear. Using data from two mooring sites within the Weddell Sea, we find a rapid intensification of the abyssal boundary current carrying AABW through Orkney Passage (OP), the most direct export pathway of AABW from the Weddell Sea, in response to periods of strong zonal wind stress and anomalous wind stress curl along the South Scotia Ridge upstream of OP. This acceleration is concomitant with a 40% reduction in northward AABW transport in late 2015. The changes in transport follow anomalous wind forcing by approximately 3 months, with the short timescale indicative of a barotropic response in the flow through OP. The bottom boundary layer over the OP's sloping topography is found to have a key role in regulating export on monthly to interannual timescales. Increased boundary current velocity leading up to the passage forms a thickened bottom boundary layer, resulting in reduced AABW thickness and density, and thus restricting northward transport of AABW through the passage. Whilst other processes are likely to dominate on longer (decadal) periods, the dynamics identified here can explain significant variability on timescales up to interannual. Plain Language Summary: Antarctic Bottom Water (AABW) is the coldest, densest water mass in the World Ocean, and plays a pivotal role in controlling the ocean's ability to store and capture heat and carbon from the atmosphere. The volume of AABW has both warmed and shrunk over the past decades, with significant variability on shorter timescales from a few months to several years. Different mechanisms have been suggestively linked to these changes; however, their relative importance remains unclear. Here, we use observational data from two moorings along the flow path of AABW from the Weddell Sea to the South Atlantic, to investigate changes in AABW properties and volume transport. Comparing temperatures at each mooring, we find a rapid acceleration of this current is driven by stronger winds across the region. This acceleration causes a warming and reduction in transport of AABW as lighter warmer waters are pushed deeper along the seabed creating a thick turbulent and unstable layer. On longer timescales, the relationship between winds and variations in AABW transport cannot be unambiguously attributed to this mechanism, as other processes could have comparable or greater impact on the transport of AABW, however the process identified here has strong relevance on shorter timescales. Key Points: Increased zonal wind stress and wind stress curl along steep bathymetry leads to a reduction in interannual northward AABW transportSpeed of abyssal boundary current transporting AABW responds rapidly to changes in wind forcing via barotropic dynamicsBarotropic acceleration of boundary current induces strengthening of downslope bottom Ekman flow, which reduces AABW thickness and transport [ABSTRACT FROM AUTHOR]

Fram Strait is one of the main gateways for fresh water leaving the Arctic Ocean toward the deep‐water formation regions of the North Atlantic. Monitoring transport through Fram Strait is important to quantify the impact of Arctic amplification on the hydrography in lower latitudes. We update existing time series from the moorings in the western Fram Strait and investigate the monthly and interannual variability of the liquid freshwater transport (FWT, reference salinity 34.9), volume transport and freshwater content between 2003 and 2020. We examine composites and correlations of sea‐level pressure (SLP) reanalysis, and remote‐sensing dynamic‐ocean topography (DOT) in the Arctic Ocean. We identify two remote forcing mechanisms of FWT: (a) North Pole convergence freshens the region north of Fram Strait 13–24 months before high FWT events. (b) Beaufort Gyre weakening allows spreading of fresh water to the margins of the Arctic Basin zero to 9 months before high FWT events. In addition a third mechanism occurs locally, (b) Fram Strait northerly winds confine freshwater to the Greenland shelf and drive stronger southward FWT. Additionally, we find a decreasing trend in the total volume transport, concurrent with weakening northerly winds and reducing north‐south DOT gradient across the strait. We also examined correlations between the Fram Strait time series and the Arctic Oscillation and Arctic Ocean Oscillation. Both are found to correlate positively with the total volume transport, while the Arctic Oscillation correlates negatively with FWT with 1‐year lag. Plain Language Summary: The East Greenland Current brings fresh water from the central Arctic Ocean to lower latitudes. The exported fresh water affects stratification, and can contribute to variations of the global meridional overturning circulation. In Fram Strait, between Greenland and Svalbard, the properties of this current have been systematically monitored using moored instruments. We present updated time series of freshwater transport from the moorings in the Fram Strait, and analyze their variability between 2003 and 2020. We identify three mechanisms that contribute to high freshwater transport in the Strait. (a) 13–24 months before, clockwise wind anomalies in the Eurasian Arctic drive converging current anomalies and freshen the area preconditioning fresh outflow events. (b) 0–9 months before, anticlockwise wind anomalies in the Canadian Arctic drive diverging current anomalies directing fresh water to the periphery and Fram Strait. (c) Northerly winds over the strait drive southward transport instantly. We find additionally that total volume transport in the Fram Strait decreases in relation to weakening northerlies that could be a result of a warming Greenland. Key Points: Fram Strait local northerly winds force instant southward volume and freshwater transportArctic Ocean large‐scale wind variability forces two distinguished lagged responses of freshwater content and transport in Fram StraitBetween 2004 and 2019 freshwater transport shows no trend but total volume transport of the East Greenland Current decreases by ∼0.1 SV/year [ABSTRACT FROM AUTHOR]

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The wind pressure caused by the high-speed passage of intercity railway trains applies a significant load on the platform screen doors, to ensure the safe of the platform screen doors and achieve reasonable design and construction goals, it is necessary to explore the distribution law and mechanism of wind pressure load on the platform screen doors first. Using Fluent software, RNG k-ε turbulence model was selected, and the control equations were discretized by finite volume method, the second-order upwind scheme and center difference scheme were used to solve the convective and diffusive fluxes, the influence of wind pressure load on platform screen doors caused by intercity train passing through stations was studied. The research results indicates: When a train passes through a station at high speed, the increase in the ross-section area of the enclosed area allows the compressed air to dissipate faster, thereby reducing the wind pressure load on the platform screen doors and minimizing the extreme values of the wind pressure load on the doors; Before the train arrives at the platform screen door, the slight change in the retreat distance between the platform screen door and the platform edge has little effect on the extreme wind pressure load of the platform screen door; After the train arrives at the platform screen door, the airflow changes and distribution in the enclosed area become more severe and complex, the increase in cross-section area makes the wind pressure load of the platform screen door more significantly affected by the change in the retreat distance of the platform screen door; The increase in train passing speed will lead to an increase in the extreme wind pressure load on the platform screen doors; During the process of the train passing through the station, the maximum load at each point of the platform screen door decreases overall along the direction of the train's travel, however, as the speed of the train passing through the station increases, the minimum load (suction) near the end of the platform screen door in the direction of the train's travel tends to increase, and this phenomenon becomes more pronounced as the speed increases. [ABSTRACT FROM AUTHOR]

Although the aerodynamic loading of wind turbine blades under various conditions has been widely studied, the radial distribution of load along the blade under various yaw conditions and with blade flapping phenomena is poorly understood. This study aims to investigate the effects of second-order flapwise vibration on the mean and fluctuation characteristics of the torque and axial thrust of wind turbines under yaw conditions using computational fluid dynamics (CFD). In the CFD model, the blades are segmented radially to comprehensively analyze the distribution patterns of torque, axial load, and tangential load. The following results are obtained. (i) After applying flapwise vibration, the torque and axial thrust of wind turbines decrease in relation to those of the rigid model, with significantly increased fluctuations. (ii) Flapwise vibration causes the blades to reciprocate along the axial direction, altering the local angle of attack and velocity of the blades relative to the incoming wind flow. This results in the contraction of the torque region from a circular shape to a complex “gear” shape, which is accompanied by evident oscillations. (iii) Compared to the tangential load, the axial load on the blades is more sensitive to flapwise vibration although both exhibit significantly enhanced fluctuations. This study not only reveals the impact of flapwise vibration on wind turbine blade performance, including the reduction of torque and axial thrust and increased operational fluctuations, but also clarifies the radial distribution patterns of blade aerodynamic characteristics, which is of great significance for optimizing wind turbine blade design and reducing fatigue risks. [ABSTRACT FROM AUTHOR]

Vertical sun control and shading devices such as louvers are essential features of modern building design. These devices are being used increasingly in the Middle Eastern region due to the extreme temperatures. These devices reduce building peak heat and cooling requirements and enhance indoor natural light. However, it is important to assess these devices so that they meet specific structural strength and serviceability criteria, because if they start to deform, discomfort for the tenants could result. Such deformation might even cause damage to parts of the building, such as the glass windows, especially if this deformation occurs repeatedly over time. An actual case study with aluminum and glass sun control devices was analyzed structurally. Aluminum devices with a twofold height curvature were made from 6-mm-thick curved tubes. They were supported by brackets at various heights with thermal expansion joints for temperature fluctuations. Aluminum devices can withstand 2.0-kPa wind loads, whereas glass fins can withstand loads of 1.8-kPa. The research assessed the induced stresses and deflections through numerical simulations using shell elements. The practical implications of this research indicate that the devices have been proven to be safe within acceptable safety standards and criteria. [ABSTRACT FROM AUTHOR]

Over the past few decades, the concept of base isolation has gained prominence as a prospective methodology for safeguarding structures against severe seismic events and wind forces. Many international building codes have recognized its effectiveness and incorporated relevant sections. This paper aims to demonstrate the exceptional performance of Lead Rubber Bearing (LRB) isolation systems through an extensive parametric study. The study showcases a significant reduction in various response parameters and emphasizes the substantial energy dissipation capabilities of the LRB system. These compelling results underscore the urgent need to develop a novel design methodology for isolated buildings in alignment with Algerian seismic regulations, which currently lack provisions for this advanced technique. The research introduces an innovative approach for LRB isolators, employing the equivalent static method. This technique is characterized by its utilization of an iterative procedure for adjusting the isolator's displacement in accordance with the mechanical and geometric attributes of the structure. To validate the proposed model, a comprehensive parametric study was conducted on a building designed in compliance with several international codes, including IBC 2000, Italian, Chinese, Japanese, Taiwanese, and Algerian codes. The results stemming from this innovative design methodology closely align with the requirements of these international codes, affirming its global applicability and relevance. [ABSTRACT FROM AUTHOR]

Winds in the nighttime upper thermosphere are often observed to mimic the ionospheric plasma convection at polar latitudes, and whether the same is true for the daytime winds remains unclear. The dayside sector is subject to large temperature gradient set up by solar irradiance and it also contains the cusp, which is a hotspot of Poynting flux and a region with the strongest soft particle precipitation. We examine daytime winds using a Scanning Doppler Imager (SDI) located at the South Pole, and investigate their distribution under steadily positive and negative IMF By conditions. The results show that daytime winds exhibit significant differences from the plasma convection. Under negative IMF By conditions, winds flow in the same direction as the plasma zonally, but have a meridional component that is strongest in the auroral zone. As a result, winds are more poleward-directed than the plasma convection within the auroral zone, and more westward-directed in the polar cap. Under positive IMF By conditions, winds can flow zonally against the plasma in certain regions. For instance, they flow westward in the polar cap despite the eastward plasma convection there, forming a large angle relative to the plasma convection. The results indicate that ion drag may not be the most dominant force for daytime winds. Although the importance of various forcing terms cannot be resolved with the utilized dataset, we speculate that the pressure gradient force in the presence of cusp heating serves as one important contributor. [ABSTRACT FROM AUTHOR]

Microstructural changes in conductive materials induced by electric current treatments, such as electromigration and electroplasticity, are critical in semiconductor and metal processing. However, owing to the inevitable thermal effect (Joule heating), the athermal effect on microstructural modifications remains obscure. This paper presents an approach of utilizing pre-micromachined structures, which obstruct current flow but maintain a thermal history similar to that of the matrix, effectively disentangling the thermal and athermal effects. A duplex stainless-steel material is selected to validate the feasibility of this method. Microstructural characterizations show that the athermal effect, especially the electron wind force (EWF), primarily governs the element diffusion and phase transformation in this study. Moreover, many σ phases (Cr-enriched) are precipitated in the micromachined structures, whereas no precipitation occurred in the matrix, suggesting that the directional EWF disrupts the Cr aggregation caused by Joule heating. Furthermore, we present a critical formula for determining the dimensions of micromachined structures of commonly used metallic materials. The proposed method may serve as an effective and powerful tool for unveiling the athermal effect on microstructural alterations. Understanding the impact of the athermal effect on microstructures is crucial for designing and manufacturing semiconductor and metal materials. Here, the authors propose a method using pre-micromachined structures to decouple thermal and athermal effects and experimentally validate its feasibility. [ABSTRACT FROM AUTHOR]

Introduction: The design of the maize metering device involves centrifugal variable diameter pneumatic and cleaning mechanisms, aiming to enhance the performance and power efficiency of pneumatic maize metering devices. Leveraging the impact of changes in centrifugal diameter and the guidance and positioning of airflow, we optimize the hole insert, seeding plate, seed limit board, and integrated front shell. This optimization facilitates the adjustment of both the quantity and posture of seed filling. As a result, seeds can form a uniform flow within the annular cavity, reducing the wind pressure necessary for regular operation and decreasing power consumption. Methods: A quadratic regression orthogonal rotation combination experiment is conducted using a self-made experiment bench, considering ground speed, wind pressure, and seeding rate as the experiment factors. Furthermore, a comparative experiment involving a novel centrifugal variable-diameter type metering device. Results: The results indicate optimal seeding performance when the ground speed is 13.2 km/h, the wind pressure is 1.2 kPa, and the feeding rate is 25 seeds/s. Under these conditions, the quality of feed index reaches 95.20%, the multi-index is 3.87%, and the miss index is 0.93%. Findings reveal that the developed seed metering device achieved a quality of feed index exceeding 93.00% across varying speeds of 12~18 km/h, aligning with the production requirements. Moreover, the actual power consumption of Type B and C is about 85.00% and 98.00% lower than Type A, standing at only 32.90 W at 18 km/h. The COP of Type C is about 86 times and 12 times that of Type A and B, respectively, meeting the demands for efficient production of maize seed metering devices. Discussion: In comparison to traditional design and structural parameter optimization methods for maize seed metering device, this study is helpful to the sustainable development of maize industry and reduce environmental pollution. [ABSTRACT FROM AUTHOR]

We examined how wind forcing affects the upper ocean response under idealized tropical cyclone (TC) conditions. In this study, we constructed three parameterized wind fields with varying spatial and temporal resolutions for TCs of different intensities and translation speeds. The simulated surface and subsurface temperatures were cooler and deeper when using the blended wind fields owing to their higher wind speeds compared to those from coarse–resolution wind fields. Additionally, TC–induced currents were significantly stronger on the right side of the TC track, with notable differences in current velocities. Similar to the increase in ocean currents, the simulated turbulent kinetic energy driven by the blended winds is significantly higher than that simulated by the coarse-resolution wind fields. These findings suggest that using high-quality wind fields to drive ocean models can enhance the accuracy of the upper ocean response to TCs. The sensitivity of the upper ocean responses to wind forcing depends on the TC's intensity and translation speed. Stronger and slower-moving TCs induce greater vertical shear and enhanced mixing. Therefore, accurate wind stress as a surface boundary condition is crucial for numerical ocean models. [ABSTRACT FROM AUTHOR]

Due to the advantages of Laplace domain in both time and frequency domains, the dynamic analysis and control tools in engineering software like MATLAB and Python have been designed based on it. Dynamic analysis of structures requires determination of the overall transfer matrix, which is obtained by multiplying the structure's transfer matrix (TM) with the load TM. With the input vector of unit intensity white-noise processes and the overall TM, the structural responses can be obtained. Furthermore, having the load TM is crucial for implementation of active control systems. In this article, the TM of along-wind loads was estimated for a tall building using the proper orthogonal decomposition (POD) method and the genetic algorithm (GA). To evaluate the effectiveness of the proposed approach, an example of a tall building was provided. The wind load cross-power spectral matrix (XPSD) was decomposed using POD technique, followed by the truncation of higher loading modes. Subsequently, the loading TM was derived by estimating the target non-linear functions with linear transfer functions through GA technique. Then, the responses of the structure were computed using the loading TM. The results demonstrated the efficacy of the proposed method in acquiring the loading TM and predicting wind-induced responses. [ABSTRACT FROM AUTHOR]

The operational efficiency and lifespan of Floating Offshore Wind Turbines (FOWTs) are adversely impacted by the inherent platform motions and undesired vibrations induced by wind and wave loads. To effectively address these effects, the control of specific structural motions is of utmost importance, with platform pitch and yaw identified as the primary Degrees Of Freedom (DOF) that require attention. This study proposes a novel utilization of Oscillating Water Columns (OWCs) as a reliable and viable solution to mitigate platform pitch and yaw motions, thereby significantly enhancing the efficiency and reducing fatigue in wind turbines. This article aims to evaluate the impact resulting from integrating OWCs within each discrete floater of a Six-Floater platform. By considering different combinations of OWCs, a comprehensive analysis of the Response Amplitude Operators (RAOs) associated with pitch and yaw motions is presented. The primary objective is to identify the most efficient arrangements of OWCs and determine suitable combinations that effectively stabilize platform pitch and yaw motions. The empirical results substantiate that specific OWC configurations exhibit notable dampening effects on both pitch and yaw motions, particularly within specific wave frequency intervals. Consequently, it can be inferred that the integration and adequate operation of OWCs facilitate a substantial improvement in the stabilization of multi-floater platforms. [ABSTRACT FROM AUTHOR]

Strong winds or typhoon disasters pose significant risks to historical buildings in many countries and regions. Although numerous researchers have discussed the damage caused by natural wind disasters, little attention has been paid to the potential impact of renovation and adaptive reuse strategies on the wind resistance performance of historical buildings—an avoidable human-induced factor. This study selected the representative ancestral hall building in Guangzhou, namely Lujiang Academy, for on-site investigation and Computational Fluid Dynamics (CFD) simulation analysis. It examined two renovation approaches: installing glass curtain walls around the courtyard and enclosing the top of the courtyard with a glass canopy. This study also assessed the roof wind pressure distribution in its unaltered state to evaluate the impact of different renovation strategies on roof wind load distribution. The results showed that installing glass curtain walls can effectively reduce the upward suction effect on the main hall roof, thereby improving its wind resistance performance. Conversely, enclosing the courtyard with a glass canopy may increase negative pressure on areas such as the eaves and corridor roofs, raising the risk of roof damage. This study systematically evaluated the renovation strategies for historical buildings, detailing the specific impacts of different retrofit measures on the wind resistance performance of building roofs. The methods and findings are significant not only for the renovation of ancestral hall heritage buildings in Guangzhou but also for providing practical scientific methods and technical strategies for the conservation and renovation of similar historical structures. This research demonstrates an effective approach to enhancing wind resistance and preventive protection for historical buildings. [ABSTRACT FROM AUTHOR]

Unstable airflow driven by natural wind forces inside a grass aerial seeding tower is a technical problem that needs to be improved. The authors used FLUENT 2020 R2 to simulate a basic nozzle unit, which is the fundamental component of a grass aerial seeding tower. The interior flow characteristics of the tower were first analyzed. Then, an optimization was undertaken to enhance the internal airflow's uniform stability, taking the cross-sectional inclination angle as the design parameter. The coefficient of variation, uniformity index, and velocity direction index were considered as constraints. The simulation results indicate that, subsequent to traversing the Laval nozzle unit, the grass seeds undergo a considerable acceleration. At an inclination angle of 15°, while ensuring the attainment of desired exit velocities, a commendable balance of uniformity and directional consistency was achieved. [ABSTRACT FROM AUTHOR]

Studies on limnology are essential to reservoir management; nevertheless, few are known about the limnological features of the Andean reservoirs in Ecuador. To overcome this limitation in the information, from December 2018 to December 2019, the limnological characteristics of El Labrado and Chanlud reservoirs in the Machángara river basin (Ecuador south) were examined. Using the light/dark bottles technique, the primary productivity (PP) of phytoplankton was studied in conjunction with (1) vertical profiles of oxygen concentrations, water temperature, nitrogen, phosphorus, alkalinity, and heterotrophic bacteria; (2) Secchi disk transparency; and (3) meteorological factors such as wind force, precipitation, and water level. Data indicate that both reservoirs are polymictic, with alkaline waters, low nutrients, and low PP rates. Despite this, a principal component analysis revealed that Chanlud exhibits higher nitrogen, alkalinity, heterotrophic bacteria, and PP values. In two approaches through multiple linear regression analysis, each per reservoir, the PP was explained mainly by water temperature, depth, light, heterotrophic bacteria, and meteorological parameters. The low concentrations of nutrients and the low residency time explain the low PP values. Likewise, the altitudinal factor (i.e., both reservoirs are 3400 m above sea level) and the low human perturbations in surrounding reservoir zones play a crucial role in explaining their poor PP. Notwithstanding the low metabolic rates, clear seasonal trends were observed in both reservoirs; the lowest PP rates occurred during the cold season. To our knowledge, this is the first limnological study of high Andean reservoirs in Ecuador. These findings should be part of Andean reservoir management protocols, contributing significantly to local conservation efforts. Additionally, they could be extrapolated as a frame of reference to similar eco-hydrological systems. [ABSTRACT FROM AUTHOR]

In this study, a spectral analysis method is proposed for a sagged cable with an optimal viscous inertial mass damper (VIMD) under random wind loads based on a generalized state-space formulation. The frequency response functions of the cable responses were evaluated for the wind force vector using complex modes orthogonal to the system matrices, from which the power spectral densities of the cable responses were readily obtained for the spectral matrix of the wind force. The accuracy and efficiency of the proposed method were verified by comparing the root mean square responses with those obtained from the time-domain and covariance analyses. The performance of two VIMDs optimized by the fixed-point method and the maximum damping ratio method was investigated for various cases of cable sag and wind properties. Serviceability failure probability analysis was also conducted using the first-passage problem. The results show that the proposed spectral method is computationally more efficient than the other two analysis methods. The VIMDs optimized for the first original cable mode were found to be highly effective in reducing cable vibration and the probability of serviceability failure. [ABSTRACT FROM AUTHOR]

Accurate wind pressure analysis on high‐rise buildings is critical for wind load prediction. However, traditional methods struggle with the inherent complexity and multiscale nature of these data. Furthermore, the high cost and practical limitations of deploying extensive sensor networks restrict the data collection capabilities. This study addresses these limitations by introducing a novel framework for optimal sensor placement on high‐rise buildings. The framework leverages the strengths of multiresolution dynamic mode decomposition (mrDMD) for feature extraction and incorporates a novel regularization term within an existing sensor placement algorithm under constraints. This innovative term enables the algorithm to consider real‐world system constraints during sensor selection, leading to a more practical and efficient solution for wind pressure analysis. mrDMD effectively analyzes the multiscale features of wind pressure data. The extracted mrDMD modes, combined with the enhanced constrained QR decomposition technique, guide the selection of informative sensor locations. This approach minimizes the required number of sensors while ensuring accurate pressure field reconstruction and adhering to real‐world placement constraints. The effectiveness of this method is validated using data from a scaled building model tested in a wind tunnel. This approach has the potential to revolutionize wind pressure analysis for high‐rise buildings, paving the way for advancements in digital twins, real‐time monitoring, and risk assessment of wind loads. [ABSTRACT FROM AUTHOR]

Accurate snow cover modeling is a high-stakes issue for mountain regions. Alpine snow evolution and spatial variability result from a multitude of complex processes including interactions between wind and snow. The SnowPappus blowing snow model was designed to add blowing snow modeling capabilities to the SURFEX/Crocus simulation system for applications across large spatial and temporal extents. This paper presents the first spatialized evaluation of this simulation system over a 902 km 2 domain in the French Alps. Here we compare snow cover simulations to the spatial distribution of snow height obtained from Pléiades satellites stereo imagery and to snow melt-out dates from Sentinel-2 and Landsat 8 time series over three snow seasons. We analyzed the sensitivity of the simulations to three different precipitation datasets and two horizontal resolutions. The evaluations are presented as a function of elevation and landform types. The results show that the SnowPappus model forced with high-resolution wind fields enhances the snow cover spatial variability at high elevations allowing a better agreement between observed and simulated spatial distributions above 2500 m and near peaks and ridges. Model improvements are not obvious at low to medium altitudes where precipitation errors are the prevailing uncertainty. Our study illustrates the necessity to consider error contributions from blowing snow, precipitation forcings, and unresolved subgrid variability for robust evaluations of spatialized snow simulations. Despite the significant effect of the unresolved spatial scales of snow transport, 250 m horizontal-resolution snow simulations using SnowPappus are found to be a promising avenue for large-scale modeling of alpine snowpacks. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to investigate the impact of varying the number of minimum quantity lubrication (MQL) nozzles, wind pressure, spindle speed and type of lubrication on surface roughness, fatigue life and tool wear in the drilling of aluminum alloy 6061-T6. Design/methodology/approach: The effect of using different lubricants such as palm oil, graphene/water nanofluid and SiO2/water in the MQL method was compared with flood and dry methods. The lubricant flow and feed rate were kept constant throughout the drilling, while the number of nozzles, wind pressure and spindle speed varied. After preparing the parts, surface roughness, fatigue life and tool wear were measured, and the results were analyzed by ANOVA. Findings: The results showed that using MQL with four nozzles and graphene/water nanofluid reduced surface roughness by 60%, followed by SiO2 nanofluid at 56%, and then by palm oil at 50%. Increasing the spindle speed in MQL mode with four nozzles using graphene nanofluid decreased surface roughness by 52% and improved fatigue life by 34% compared to the dry mode. SEM results showed that tool wear and deformation rates significantly decreased. Increasing the number of nozzles caused the fluid particles to penetrate the cutting area, resulting in improved tool cooling with lubrication in all directions. Originality/value: Numerous attempts have been made worldwide to eliminate industrial lubricants due to environmental pollution. In this research, using nanofluid with wind pressure in MQL reduces environmental impacts and production costs while improving the quality of the final workpiece more than flood and dry methods. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2024-0021/ [ABSTRACT FROM AUTHOR]

Natural ventilation is the most cost-effective environmental control method for protected horticulture. To overcome the issues associated with high temperatures in greenhouses, analyzing their ventilation characteristics and maximizing their natural ventilation performance are essential. Therefore, in this study, the natural ventilation performance of arched single-span plastic greenhouses with screened side openings was empirically investigated. Three identical single-span plastic greenhouses were used in this study, each with different side-opening heights. Temperature and wind-speed data were collected, and the ventilation-volume flow rate was calculated considering both buoyancy and wind forces. The natural ventilation performance of the greenhouses was strongly and positively correlated with the ventilation-area ratio and outdoor wind speed. The ventilation rate increased linearly with an increase in the ventilation-area ratio and high outdoor wind speeds. However, the association between ventilation performance and indoor–outdoor temperature differences was not strong. When the ratios of ventilation areas in the greenhouse were changed to 0.08, 0.19, and 0.29, the average indoor–outdoor temperature differences were 14.0, 10.1, and 7.7 °C, respectively, and the ventilation rates were 0.0081, 0.0196, and 0.0315 m3 s−1 m−2, respectively. The proportion of wind in the total ventilation performance was high with a low ratio of ventilation openings and high outdoor wind speeds. However, the proportion of the buoyancy was high, with a high ratio of ventilation openings and a large indoor–outdoor temperature difference. Overall, this study provides foundational insights for optimizing the design and evaluation of ventilation openings in greenhouses, considering the outdoor wind speed. [ABSTRACT FROM AUTHOR]

AbstractDebonding existence at the interface of Al liner and overwrapped CFRP laminates may endanger the structural integrity of type-III composite vessel. In this study, CFRP and GFRP wound composite pressure vessels with Teflon sheet inserted artificial axisymmetric defect in Al–CFRP interface and without any defect were manufactured and nitrogen gas inside cooling experiments of the vessels were conducted. During the cooling axial strain and temperature responses at distinct locations of outer GFRP hoop surface were monitored to study the thermoelastic crack growth along Al–CFRP interface. The nonlinear strain response obtained under temperature change in the defect bearing specimen was considered as a result of Al–CFRP interface crack growth. Furthermore, to expose the Al–CFRP interfacial cross section of post-cooling specimen, destructive cutting and optical microscopy were performed. The Al–CFRP cross sectional microscopic observations at cutting planes showed Al–CFRP interface crack growth due to cooling in the defective specimen. Afterwards, the GFRP hoop surface axial strain experimental data fitted inversely to the surface based cohesive zone modeling (CZM) simulation results to estimate the Al–CFRP interface cohesive strength, and fracture energy. [ABSTRACT FROM AUTHOR]