Horizontal Shear Research Articles

РЕКОНСТРУКЦИЯ ТЕКТОНИЧЕСКИХ НАПРЯЖЕНИЙ ЦЕНТРАЛЬНОГО САХАЛИНА

The article presents the reconstruction of the tectonic stress field of the central part Sakhalin Island, obtained as a result of field tectonophysical studies in 2020–2022. The measurements made it possible to determine the predominant orientation of the main slickensides systems with different kinematics. The territory of Central Sakhalin is characterized by mainly subvertical orientation of the axis of maximum compression, as well as the subhorizontal and predominantly submeridionally directed axis of minimum compression (extension). The main revealed feature of Central Sakhalin is the predominance of horizontal extension as a type of stress state for the entire area. In its western part, horizontal shear and horizontal compression are significant. The number of horizontal extension conditions increases in the near-axial and eastern part of Central Sakhalin, closer to the Sea of Okhotsk. We found the cardinal difference between the obtained results of the stress field reconstruction and the results of similar studies in other geodynamically active regions of the country.

SNELM: SqueezeNet-Guided ELM for COVID-19 Recognition.

(Aim) The COVID-19 has caused 6.26 million deaths and 522.06 million confirmed cases till 17/May/2022. Chest computed tomography is a precise way to help clinicians diagnose COVID-19 patients. (Method) Two datasets are chosen for this study. The multiple-way data augmentation, including speckle noise, random translation, scaling, salt-and-pepper noise, vertical shear, Gamma correction, rotation, Gaussian noise, and horizontal shear, is harnessed to increase the size of the training set. Then, the SqueezeNet (SN) with complex bypass is used to generate SN features. Finally, the extreme learning machine (ELM) is used to serve as the classifier due to its simplicity of usage, quick learning speed, and great generalization performances. The number of hidden neurons in ELM is set to 2000. Ten runs of 10-fold cross-validation are implemented to generate impartial results. (Result) For the 296-image dataset, our SNELM model attains a sensitivity of 96.35 ± 1.50%, a specificity of 96.08 ± 1.05%, a precision of 96.10 ± 1.00%, and an accuracy of 96.22 ± 0.94%. For the 640-image dataset, the SNELM attains a sensitivity of 96.00 ± 1.25%, a specificity of 96.28 ± 1.16%, a precision of 96.28 ± 1.13%, and an accuracy of 96.14 ± 0.96%. (Conclusion) The proposed SNELM model is successful in diagnosing COVID-19. The performances of our model are higher than seven state-of-the-art COVID-19 recognition models.

Seismic in-plane displacement capacity of masonry barrel vaults: the role of constructive aspects

Historic masonry vaults are one of the most vulnerable elements with respect to the seismic action. Cracks are often detected after post-earthquake surveys. However, it is difficult to directly link the observed damage to causes. Different mechanisms can occur during an earthquake, such as in-plane horizontal shear distortion or longitudinal opening/closing of the abutments. These mechanisms are not necessarily associated to a specific crack pattern, since other factors are involved in the determination of the detected crack status. Among these factors, constructive aspects (such as the brick pattern) play a major role. This study aims at investigating the possible correlation between constructive aspects and the crack pattern in barrel vaults subjected to in-plane shear mechanism. Numerical simulations are carried out on an ideal circular vault with a rectangular base of dimensions 3.1 × 5.3 m, and rise of 1.175 m. Three brick patterns are considered: radial, diagonal and vertical. In order to investigate these aspects, a micro-modelling numerical approach has been adopted. Results are presented in terms of ultimate displacement capacity, collapse mechanisms and crack pattern charts.

Wind inflow observation from load harmonics via neural networks: A simulation and field study

In this work, feed-forward neural networks are used to estimate the inflow of a wind turbine in real time during operation. A previously published method achieved this capability by correlating the turbine response to the wind inflow via a piecewise-linear model. Specifically, the existing formulation used the once-per-revolution harmonics of both in- and out-of-plane blade bending moments to estimate four wind parameters: the vertical and horizontal shears, and the vertical and horizontal misalignment angles. The novel method presented here builds on the same concept, but replaces the linear model with neural networks. Compared to the previous approach, the neural-based one is simpler to tune and use, because it decouples the wind parameters, which can be observed each one independently from the others. The proposed formulation is tested using both aeroservoelastic simulations and field data obtained on a 3.5 MW machine. In the field, independent measurements of the inflow are provided by a nearby hub-tall met mast, providing data for the training and verification of the wind observer. Notwithstanding some limitations of the experimental setup, results indicate that the neural networks produce estimates of the shears and yaw misalignment angle with accuracies compatible with typical use cases in wind turbine and wind farm control. Additionally, the neural-based observer appears to slightly outperform the original formulation in the lower wind speed range, where stronger nonlinearities in the load-wind mapping can occur.

Short-period planetary-scale waves in a Venus general circulation model: Rotational and divergent component structures and energy conversions

To elucidate the generation and coupling of the short-period waves in the Venus atmosphere, we investigated the three-dimensional wave structure in an AORI (Atmosphere and Ocean Research Institute, University of Tokyo, Japan) Venus general circulation model. The most predominant waves are 7.5-day waves with zonal wavenumber 1 and are slower than observed planetary-scale 5.5-day waves around the cloud bottom (∼50 km), associated with a slower zonal flow in the model. The 7.5-day waves comprise three types: Type I, a Rossby wave in the upper cloud layer; Type II, a Rossby wave around the polar tropopause (∼50 km); and Type III, an equatorial Kelvin-like wave around and below the cloud bottom.Around the cloud top (65–70 km), the Rossby wave (Type I) has a rotational eddy structure and is produced by potential-energy conversion from zonal mean to eddy, suggesting baroclinic instability in the cloud layer. The geopotential of the Rossby wave in the upper cloud layer vertically connects to that of the equatorial Kelvin-like wave (Type III) across the critical line at ∼55 km and 30° latitudes. At the cloud bottom (∼50 km), the Kelvin-like wave and Rossby wave (Type II) are separated at a critical latitude around the cloud bottom, but are horizontally jointed with the stream function and velocity potential at the critical latitude. These two waves are major equatorward momentum transporters and are generated by horizontal shear (or barotropic) and baroclinic instabilities associated with energy conversion at the critical line. For high-latitude Rossby waves around the polar tropopause (Type II), the positive kinetic-energy conversion by vertical momentum transport is predominant, tending to relax the vertical shear of the zonal flow, leading in turn to relaxation of the horizontal temperature gradient under the cyclostrophic thermal wind. In contrast, the negative potential-energy conversion tends to produce the horizontal temperature gradient in the lower atmosphere where the solar insolation is very weak.The equatorial jet core rotating with a 7.5-day period is composed of both divergent and rotational wind components of the equatorial Kelvin-like wave at the cloud bottom. Above the critical level of the Kelvin-like wave, the equatorial Rossby wave (downward and equatorward flank of the Type I wave) appears at around 54 km and is produced by the barotropic energy conversion.

Comparative dynamic analysis of SCR and LWR in the coupled platform–mooring–riser system under internal solitary wave conditions

As a frequently occurring and widely distributed environmental load, an internal solitary wave (ISW) always appears with a large amplitude and may result in the instability of deepwater structures and offshore accidents. In this study, a self-developed program was established to describe the dynamic behavior of a coupled platform–mooring–riser system. The response of the platform is based on the rigid body dynamics theory, that of the risers/mooring lines is obtained by the lump mass method, and the coupled effect between them is achieved by a semi-coupled analysis. Two types of riser configurations, steel catenary risers (SCRs) and lazy-wave steel catenary risers (LWRs), in the coupled system were compared under only ISWs and combined excitation of ISWs and random waves. The numerical results were proven to be reliable through validation against previous literature. The results show that different riser configurations have little influence on the platform response or mooring top tension. Both riser configurations exhibit a second-order deformation mode along the riser length and a half-wave shape with time. Additionally, a mutation in the horizontal tension, shear force, and bending moment occurs near the ISW interface. Compared with SCRs, LWRs always produce larger motion characteristics and responses with time differences owing to their complex configuration.

STUDY ON SEISMIC RESPONSE OF STEEL FRAMES INTEGRATED WITH BRACING SYSTEMS

Increasing lateral stiffness and energy dissipation capacity is considered an effective solution to improve the seismic performance of building structures. The bracing system is one of the most effective and reliable solutions in seismic-resistant design for frame structures. In this study, the step-by-step of design for a bracing system according to the displacement-based design method is detailed. A typical study is performed on a steel-braced frame structure, subjected to earthquake ground motion to evaluate the effectiveness of the solution. The obtained results show that the bracing has good effects in reducing the horizontal displacement and shear force for building structures.

Lateral displacement mode of column-supported modular steel structures with semi-rigid connections

The lateral displacement of a column-supported modular steel structure with semi-rigid connections (CSMSS-SRC) owing to lateral loading was investigated to determine the corresponding lateral displacement mode and establish a foundation for a direct displacement-based seismic design method. Theoretical equations for the lateral displacement caused by the bending deformation of beams and columns, axial deformation of columns, and shear deformation of the vertical inter-module connections were theoretically derived using slope–deflection equations, unit-load method, and shear deformation definition, respectively. Two simplified single frame finite element models were then established to verify the theoretical equations and study the effects of the rotational and horizontal shear stiffnesses of the vertical inter-module connections on the lateral displacement of the CSMSS-SRC. The results showed that the proposed lateral displacement equations are highly accurate. Furthermore, although the rotational stiffness of the vertical inter-module connection did not exert an appreciable effect on the lateral displacement of the CSMSS-SRC, its horizontal shear stiffness did. These results are expected to provide a reference for the engineering design of CSMSS-SRC.

Experimental and Numerical Study on Response Characteristics of Airport Pavement Subjected to Wetting in Silt Subgrade

Silt is often selected as the filling soil in Northwest and North China. “Pot cover effect” or rainfall infiltration are easily to cause localized wetting during the service period of airport. The response characteristics of pavement derived from aircraft loading under wetting condition are the basis to explore the evolution law of pavement damage. To investigate this response characteristics for different parameters of pavement under wetting condition, a self-developed model test system was developed, and the verified numerical model was then established. The interaction mechanisms of pavement slabs, and the influence of wetting on mechanical response in loading area of pavement under different pavement parameters were analyzed. The results showed that the increased vertical deformation depends on water-holding capacity of silt, and the vertical deformation under loading is little affected by pavement parameters. The peak shear stress and the increased peak shear stress derived from wetting at the bottom of pavement layers are largely influenced by elastic modulus of base course. For cement concrete pavement, the increase in load transfer capacity of joints cannot decrease the increase of peak stress, including horizontal stress and shear stress, derived from wetting. The increase in load transfer capacity of joints can decrease the stress concentration in surface layer, while the elastic modulus of surface layer has little influence. For bituminous pavement, optimal parameters of base course can be obtained to decrease the peak stress and the increase of peak stress derived from wetting in subgrade. The research can provide technical basis for the structure design, optimization, and disease treatment of pavement in airport engineering.

Experimental and theoretical investigation of prefabricated separated core tube flange column connection joint

This paper suggests a separated core tube flange connection column joint to ensure the horizontal shear performance of box section steel columns at the flange connection to meet the performance requirements of column-to-column connection in high-rise buildings and the effective connection of steel columns at the joints. Low cycle reciprocating loading tests were conducted on three specimens with different parameters (separated core tube and stiffeners) to study the seismic mechanical performance of the connection and the finite element analysis (FEA) of separated core tube column connection joint was performed. The result of the experimental study shows that the separated core tube connection joints have fuller hysteresis curves and higher energy dissipation performance, as well as less high-strength bolt tension at the same interlayer displacement angle. This investigation provides experimental evidence of the deformation compatibility of the separated core tube connection. The mechanical properties of the separated core tube connection is basically the same as that of the welded connection, which can realize the rigid connection of the steel box section column. According to the numerical simulation, the failure mode and mechanism of the connection were obtained. Based on the results of tests and the finite element numerical model, further analysis to the rotational performance of the separated core tube flange connection joint in elasto-plastic phase and yield-hardening phase is carried out, and a three-stage bearing capacity calculation theory of the joint in the seismic process is proposed, which was verified by the test and FEA.

Residual flexural behaviour comparison between composite and monolithic beams after fire exposure

Fourteen T-shaped composite beams and seven T-shaped monolithic beams were tested after fire exposure. To investigate their distinct residual flexural behaviour, the beams, which had different load ratios and thicknesses of precast slabs, were exposed to specific fire exposure times (60, 90, and 120 min) in a fire furnace and loaded to failure after natural cooling. The results showed that the residual flexural capacity of the composite beams was generally lower than that of monolithic beams. The fire exposure time was found to dominantly influence the residual flexural capacity of the composite beams. Increasing the thickness of the precast slabs can slightly enhance the residual strength of the composite beams. However, the horizontal cracks at the interface between the precast and cast-in-place concrete slabs of the composite beams reduced the horizontal shear strength and further increased the horizontal slip along this interface. Accordingly, a finite element model of the composite beams was proposed. A three-dimensional spring element was introduced into the model to consider the effect of slip at the concrete–concrete interface. To predict the residual flexural capacity of the composite beams, based on the 500°C-isotherm method, three modified equations suitable for the Chinese, American, and European codes were proposed. In comparing the test values, the modified equation applicable to the European code is recommended for subsequent predictions.

Revised mixing coefficient scaling for sheared stably stratified turbulence

We revisit and extend the turbulent Froude number ( $Fr_k$ ) scaling for the mixing coefficient ( $\varGamma$ ) introduced by Garanaik & Venayagamoorthy (GV) (J. Fluid Mech., vol. 867, 2019, pp. 323–333) by directly incorporating the effects of mean shear through the non-dimensional shear parameter $S_{\ast } = S k/\epsilon _k$ . For flows where the effects of mean shear are stronger than the background vertical stratification, we find $\varGamma \sim Fr_k^{-2} S_\ast ^{-1}$ for weakly stratified sheared turbulence and $\varGamma \sim Fr_k^{-1}S_\ast ^{-1}$ for moderately stratified sheared turbulence. The scaling procedure is inconclusive for strongly stratified sheared turbulence, but using two independent datasets of homogeneous, sheared, stably stratified turbulence, we empirically observe $\varGamma \sim Fr_k^{-0.5} S_\ast ^{-1}$ . Our revised scaling better collapses both datasets compared with the original GV scaling, and we note that the moderately stratified sheared regime is extremely narrow (or maybe even non-existent). We also apply our scaling to the time-varying open channel simulations of Issaev et al. (J. Fluid Mech., vol. 935, 2022) and observe $\varGamma \sim Fr_k^{-2}S_\ast ^{-1}$ for weakly stratified sheared turbulence, but we observe deviations from our revised scaling for moderate and strong stratifications due to time-varying mean shear and vertical transport. Finally, we apply our revised scaling to field measurements of Conry, Kit & Fernando (Environ. Fluid Mech., vol. 20, 2020, pp. 1177–1197) and observe $\varGamma \sim Fr_k^{-2} S_\ast ^{-1}$ . We emphasize that our revised scaling is applicable only for stably stratified, vertically sheared turbulence with weak spatio-temporal variations of the mean shear and stratification, and we expect different scaling to apply when additional effects such as depth-varying radiative heating/cooling are present or when the orientation of the mean shear relative to the gravity vector is modified (e.g. horizontal shear).

Impacts of regional wind circulations on aerosol pollution and planetary boundary layer structure in Metro Manila, Philippines

Fine particulate matter (PM2.5) concentrations in Metro Manila, Philippines have consistently exceeded the guideline values set by the World Health Organization (WHO). Although there has been much progress in understanding the components and sources of PM2.5, limited research has been done on the influence of meteorological factors. In particular, the influence of the planetary boundary layer height (PBLH) on PM2.5 concentration has not been studied due to inadequate observations. From January 2019–June 2020, measurements from a High Spectral Resolution Lidar (HSRL) filled this gap and allowed for PBLH estimation and aerosol typing. This paper investigates the roles of PBLH and regional and local wind circulations on the temporal evolution of aerosol pollution. Results show that daytime and nighttime PBLH variability is associated with solar heating and radiative cooling, respectively. Cloud-free conditions during the dry season yield a higher PBL growth rate than during the wet season when lower daytime and elevated nighttime PBLH are observed. Lower PM2.5 levels are generally observed during daytime when PBLH is at its maximum. However, the PBLH has a significant inverse correlation with PM2.5 only in the months of December-January-February. We find that horizontal directional wind shear between synoptic and mesoscale circulations confounds the PM2.5 - PBLH relationship by creating stagnant conditions conducive to aerosol accumulation. The lower 20% of PM2.5 concentrations occur during the prevalence of strong monsoon winds. On the other hand, the upper 80% are found during the occurrence of compound mesoscale winds (i.e., sea/land/lake/valley/mountain breezes and channeling monsoon winds). In addition, mountain breeze is found to be associated with lifting of aerosols, resulting in multi-layering within the PBL. The findings in the present study emphasize the role of complex topography and mesoscale scale winds arising from the landscape on aerosol pollution variability.

Quantification of QLCS Tornadogenesis, Associated Characteristics, and Environments across a Large Sample

Abstract The skillful anticipation of tornadoes produced by quasi-linear convective systems (QLCSs) is a well-known forecasting challenge. This study was motivated by the possibility that warning accuracy of QLCS tornadoes depends on the processes leading to tornadogenesis, namely, one that is dominated by an apparent release of horizontal shearing instability [shearing instability dominant (SID)] and one by a pre-tornadic mesocyclone [pre-tornadic mesocyclone dominant (PMD)] and its associated generative mechanisms. The manual classification of the genesis of 530 QLCS tornadoes as either SID or PMD was performed using heuristic, yet process-driven criteria based on single-Doppler radar (WSR-88D) data. This included 214, 213, and 103 tornadoes that occurred during 2019, 2017, and 2016, respectively. As a function of tornadogenesis process, 36% were classified as SID, and 60% were classified as PMD; the remaining 4% could not be classified. Approximately 30% of the SID cases were operationally warned prior to tornadogenesis, compared to 44% of the PMD cases. PMD tornadoes were also more common during the warm season and displayed a diurnal, midafternoon peak in frequency. Finally, SID cases were more likely to be associated with QLCS tornado outbreaks but tended to be slightly shorter lived. A complementary effort to investigate environmental characteristics of QLCS tornadogenesis revealed differences between SID and PMD cases. MLCAPE was relatively larger for warm-season SID cases, and 0–3-km SRH was relatively larger in warm-season PMD cases. Additionally, pre-tornadic frontogenesis was more prominent for cool-season SID cases, suggestive of a more significant role of the larger-scale meteorological forcing in vertical vorticity that fosters tornadogenesis through SID processes.

In-plane shear strength of solid clay brick masonry reinforced with near surface mounted steel bars

Structural walls made of solid brick masonry have been used for centuries in old buildings, which are vulnerable to earthquakes. Reinforcing this type of walls may increase the overall building seismic strength. In this paper, the in-plane behaviour of these types of walls, both plain and reinforced, was experimentally assessed through triplets shear tests. The reinforcement considered, with near surface mounted (NSF) steel bars, has already been studied in the scope of a broader ongoing research project. The in-plane strength of brick masonry walls is of utmost relevance for seismic resistance and strongly depends on their resistance to sliding that may occur along the horizontal mortar interfaces. The bricks and the laying mortars tested correspond to walls of buildings built between 1920 and 1950 that may be found in Lisbon and other cities. Triplet specimens (made of three stacked bricks connected by a laying mortar) were built and tested. Two types of mortar compositions were used, of an earlier and a later phase within the period referred above. Both types included unreinforced specimens and specimens reinforced with steel bars of different types. The specimens were subjected to direct horizontal shear tests to determine the relevant properties of the assemblage, namely the cohesion and friction angle of the brick mortar joints. The results obtained in this study may be used in the numerical modelling of ancient buildings with brick masonry walls granting a better correlation with real behaviour.

A Revised Meiyu-Season Onset Index for Taiwan Based on ERA5

Revisiting the defined Meiyu onset of Central Weather Bureau (CWB), this study applied a newer reanalysis dataset and added multiple timing and duration criteria to improve the Meiyu onset index. The previous Meiyu onset index was based on horizontal and vertical wind shears using older-generation reanalysis data. The horizontal shear captures the cyclonic vorticity while the vertical shear depicts overturning. However, this older index tends to predict the onset date too early from the actual maximum precipitation. After applying the modification that is described in this paper, the newer Meiyu onset index consistently leads the maximum precipitation in Taiwan only by a few days, except for two years over the 30-year analysis period. The implication of this modified and improved Meiyu onset index is that it can substitute model precipitation that tends to be problematic, as well as studying climate change impacts.

Flexible support of a pile embedded in unsaturated soil under Rayleigh waves

AbstractUnder the action of Rayleigh waves, pile head is easy to rotate with a concrete pile cap, and pure fixed‐head condition is rarely achieved, which is a common phenomenon for it usually occurs on the precast piles with insufficient anchorage. In addition, the propagation characteristics of Rayleigh wave have been changed significantly due to the existence of capillary pressure and the coupling between phases in unsaturated soil, which significantly affects the pile‐soil interaction. In order to study the above problems, a coupled vibration model of unsaturated soil–pile system subjected to Rayleigh waves is established on the basis that the pile cap is equivalent to a rigid mass block. Meanwhile, the soil constitution is simplified to linear‐elastic and small deformations are assumed to occur during the vibration phase of soil–pile system. Then, the horizontal dynamic response of a homogeneous free‐field unsaturated soil caused by propagating Rayleigh waves is obtained by using operator decomposition theory and variable separation method. The dynamic equilibrium equation of a pile is established by using the dynamic Winkler model and the Timoshenko beam theory, and the analytical solutions of the horizontal displacement, rotation angle, bending moment and shear force of pile body are derived according to the boundary conditions of flexible constraint of pile top. Based on the present solutions, the rationality of the proposed model is verified by comparing with the previous research results. Through parametric study, the influence of rotational stiffness and yield bending moment of pile top on the horizontal dynamic characteristics of Rayleigh waves induced pile is investigated in detailed. The analysis results can be utilized for the seismic design of pile foundation under Rayleigh waves.

Analysis of the Three-Dimensional Structure of the Misocyclones Generating Waterspouts Observed by Phased Array Weather Radar: Case Study on 15 May 2017 in Okinawa Prefecture, Japan

Tornadoes are one of the most severe meteorological phenomena on the earth and their high winds cause serious damage to society. It is well known that vortices (mesocyclone or misocyclone, depending on their scale) in convective clouds contribute to tornadogenesis. High temporal resolution radar observations are necessary to elucidate the mechanism of tornadogenesis because convective clouds change drastically over time. This study focused on waterspouts that occurred on 15 May 2017 near Okinawa, Japan. Using Phased Array Weather Radar (PAWR) data, which provide three-dimensional data with high temporal resolution (every 30 s), radar reflectivity factors and Doppler velocity data were used to detect the three-dimensional structure of vortices. Using PAWR data, vorticities and diameters of these misocyclones were detected every 30 s and their potential vorticities, which are only possible because of the three-dimensional observation by PAWR, were calculated to understand the vortex generation and advection. The structures of two misocyclones (MC1 and MC2) were detected from Doppler velocity patterns. Combined with the radar reflectivity analysis, MC2 can be divided into two misocyclones (MC2a and MC2b). Potential vorticity of MC1 increased with time, probably because an outflow from the strong echo enhanced the lower horizontal shear. Potential vorticities in MC2a and MC2b were conserved in each period, with MC2b being nearly twice as large as MC2a.

A curious case of the Indian Summer Monsoon 2020: The influence of Barotropic Rossby Waves and the monsoon depressions

The seasonal summer monsoon rainfall over India has substantially depended on the synoptic-scale systems such as monsoon lows and depressions. India has received above-average rainfall during the 2020 summer monsoon season. Total 12 Low Pressure Areas (LPAs) formed in the north Indian Ocean during summer 2020 (in JJAS season). The significance of this monsoon season is that August 2020 received the highest all-India rainfall in the past 44 years since 1976. This is accompanied by around 50% of the total seasonal LPAs formed in August 2020, none of which intensified into a monsoon depression (MDs). This study attempts to understand the characteristic features of monsoon rainfall during August 2020 and explore the plausible mechanisms behind the LPAs not intensifying/concentrating as MDs. It is noted that the anomalous warming over the Northern Parts of the Arabian Sea (NPAS) resulted in increased convection over this region in August 2020, as a result, strong low-level convergence is observed. In addition to this convergence, strong northwesterly winds emanating from central Asia merged with the enhanced cross-equatorial monsoon flow. However, this strong flow over the Arabian Sea sheared/dissociated into two branches: one extending up to northwest (NW) India along the monsoon trough, another one diverging into an anticyclone over the south Bay of Bengal (SBOB), which reduced the horizontal shear there (Barotropic Instability). This anticyclone strength over the SBOB and its westward shift is determined by the western north Pacific (WNP) anticyclone. Our analysis suggests that due to the poor barotropic instability over the head BOB, LPAs could not develop into MDs. Additionally, upper level (200 hPa) barotropic Rossby wave in August 2020 remains stationary over South Central Asia and retrogressed with a northeast to southwest orientation. It determined the path of movement of the low-level disturbance beneath and affected the all-India rainfall by virtue of enhanced rainfall over NW & Western Ghats (WG) regions. The interplay of the barotropic Rossby wave alongside low-level anticyclone over the WNP accompanied by local conditions caused the above normal rainfall over India in August 2020, even though there are adverse dynamical conditions. We have also verified these mechanisms in Community Earth System Model Large Ensemble (CESM-LE) model simulations, analysis shows that model has a limited skill to simulate the changes in the monsoon rainfall and associated circulation and failed to capture the mid-latitude circulation impact on ISM rainfall.

Coupled Resonance Mechanism of Interface Stratification of Thin Coating Structures Excited by Horizontal Shear Waves

The coupled resonance mechanism of interface stratification of thin coating structures excited by horizontal shear waves is investigated by the forced vibration solution derived from the global matrix method, the integral transformation method, and the plane wave perturbation method. The interface shear stress reaches the peak at coupling resonance frequencies which are an inherent property of the structure, and decreases with the increase of coating thickness or the increase of shear wave velocity difference between the substrate and coating. At the coupling resonance frequency, the thin coating structure is more easily stratified at the interface. The result could provide a theoretical basis for the popularization and application of ultrasonic deicing/defrosting/de-accretion technology.