Direct Response Research Articles

Unveiling the mechanical anisotropy and related deformation mechanisms of heterostructured Mg alloy laminate with unique texture feature

In this study, a well-bonded AZ31/ZK60/AZ31 sandwich-structured laminate was prepared using extrusion. Microstructural heterogeneities in grain size, precipitate phases, and texture were evident between the constituent layers. Tensile testing revealed significant mechanical anisotropy in the laminates along the extrusion direction (ED), transverse direction (TD), and 45° directions, with the 45° direction samples exhibiting the highest tensile ductility, while ED and TD samples showed similar high strength. In-situ electron backscatter diffraction and slip trace analysis indicated that the heterogeneities in grain size and precipitates had minimal influence on the mechanical anisotropy of the laminates. Instead, texture emerged as the primary influencing factor, as it affected the initiation difficulty of basal slip and extension twinning mechanisms in various directions, thereby influencing the deformation coordination between the successive layers and resulting in varied mechanical responses in different directions.

Multifunctional and tunable bandpass filters with RF codesigned isolator and impedance matching capabilities

Abstract This paper presents the radio frequency (RF) design and experimental validation of a multifunctional bandpass filtering (BPF) concept with center frequency tunability and RF codesigned isolator and impedance matching functionality. The multifunctional bandpass filter/isolator (BPFI) concept combines frequency-tunable reciprocal resonators and nonreciprocal frequency-selective stages (NFSs) to realize center frequency tunability and fully directional transfer characteristics. The NFS, as the core component of the BPFI concept, exhibits frequency-selective transmission response in the forward direction and signal cancellation in the reverse direction. Its tunability is achieved by combining a transistor-based network with a tunable capacitively loaded coupled-line section. Furthermore, the NFS facilitates matching of different source loads allowing for the BPFIs to be used as reconfigurable matching networks. For experimental validation, an NFS and two BPFIs were designed, manufactured, and measured at L band. Their features include (i) NFS: center frequency tuning from 1.55 to 1.9 GHz with maximum directivity from 20 to 52 dB and gain from 0.3 to 1.3 dB. (ii) BPFI (topology A): center frequency tuning from 1.52 to 1.9 GHz with maximum directivity from 20 to 44 dB and gain from −1.5 to −0.5 dB. (iii) BPFI (topology C): ability to match complex loads with 26 + j18 Ω and 26 − j14 Ω.

Topological protection revealed by real-time longitudinal and transverse transport measurements

Topology is essential for achieving unchanged (or protected) quantum properties in the presence of perturbations. A challenge facing the application is the variable protection levels displayed in real systems associated with the reconstructive behaviors of the dissipationless modes. Despite various insights on potential causes of backscattering, the edge-state-based approach is incomplete because the bulk states also contribute indispensably. This study investigates sample-scale reconstruction where dissipationless modes are global objects instead of being restricted to the sample edge. An integer quantum Hall effect hosted in a Corbino geometry is adopted and brought to the verge of a breakdown. Two independent and simultaneous detections are performed to capture transport responses in both longitudinal and transverse directions. The real-time correspondence between orthogonal results confirms two facts. 1. Dissipationless modes undergo frequent reconstruction in response to electrochemical potential changes, causing dissipationless current paths to expand transversely into the bulk while preserving chirality. A breakdown only occurs when a backscattering emerges between reconstructed dissipationless current paths bridging opposite edge contacts. 2. Topological protection is subject to an interplay of disorder, electron-electron interaction, and topology. The proposed reconstruction mechanism qualitatively explains the robustness variations, beneficial for protection optimization.

Fracture behavior of 3D-printed thermoplastics—A dilemma of fracture toughness versus fracture energy

The Material Extrusion (ME) technique in 3D printing facilitates the production of thermoplastic materials with diverse cellular or lattice-like infill geometries, enabling the creation of lightweight, high-performance materials. This study investigates the influence of infill geometry and relative density on the fracture behavior of 3D-printed thermoplastics produced through ME. Polylactic acid (PLA) is used as the model material, with unit cell geometries-square, triangle, and Kagome-and relative densities ranging from 0.4 to 0.8 explored. Tensile tests are first conducted to determine in-plane elastic moduli in two orthogonal directions, accounting for unit cell anisotropy. These results are employed in effective fracture energy calculations. Compact tension fracture tests follow, quantitatively characterize crack growth characteristics in both directions. In both tests, digital image correlation method is used to measure full field strain distributions. Three significant findings emerge. First, there is a power scaling relationship between Elastic Modulus and relative density across all unit cells, with Kagome exhibiting the highest correlation constant. Triangle and Kagome unit cells show negligible orthotropic responses in perpendicular directions for varying relative densities. Second, the relationship between nondimensional fracture toughness and relative density follows a similar scaling law, with minor variations depending on unit cell type. The correlation factor slightly dependens on unit cell geometry but remains around 3 across the the examined relative density range. Third, considering the dissipation of inelastic fracture energy, both triangle and Kagome unit cell geometries demonstrate an order of magnitude higher effective fracture energy (i.e., crack growth resistance) compared to the square unit cell. This is associated with toughening mechanisms such as crack deflection and bifurcation. These findings highlight the disparity between fracture toughness and effective fracture energy in assessing the fracture resistance of 3D-printed thermoplastics, clearly demonstrating that fracture toughness alone is insufficient for a comprehensive assessment. The proposed scaling laws provide predictive insights into the fracture toughness of polymeric materials produced via the ME method.

Numerical simulation and experimental study of the dynamic characteristics of a gas turbine rotor system with beam sea and head sea excitation

Vibration analysis is crucial for studying rotor dynamics. The gas turbine rotor system is subjected to complex alternating loads during navigation, resulting in vibrations transmitted to the bearings that alter the system’s dynamic characteristics. Based on the similarity law of the wave resistance test, a hull model was established. Beam sea and head sea tests were conducted in the towing pool to measure the acceleration response at the key positions. A finite element model of the turbine rotor system was established, and the test data were imported into the model after wavelet noise reduction and resampling to calculate the vibration response at the front and rear bearing points. The vibration responses transmitted to different locations and directions caused by beam sea and head sea conditions were analyzed. A comparison and analysis were conducted on the acceleration responses in various locations and directions under beam sea or head sea conditions. The equivalent von Mises stress distribution of the gas turbine rotor system under beam sea and head sea loads was obtained. The vibration transfer model was verified for accuracy and can be used to quickly analyze the vibration response of bearings under wave load transfer. This study provides a theoretical basis and reference for enhancing the stability of the gas turbine rotor system.

Progressive failure analysis of laminar composites under compression using smeared crack-band damage model and full layerwise theory

This paper presents an original finite element (FE) model that integrates the smeared crack band (SCB) approach and full layerwise plate theory (FLWT). The model enhances the computational efficiency of progressive failure analysis (PFA) of laminar composites in compression, by utilizing the layerwise approach which reduces a 3D model to a 2D one. The model distributes damage throughout the FE domain, with fracture mechanisms represented by material stiffness degradation controlled by damage variables (based on equivalent strains specifically defined for each failure mode). Mesh dependency issues are addressed by scaling fracture energy using a characteristic element length, and failure initiation and modes are determined using the 3D Hashin failure criterion.Accurately describing lamina response in fiber direction under compression requires linear-brittle softening with a stress plateau. The study showed that a model considering 30 % of residual stress accurately predicts maximum stress regardless of mesh refinement, demonstrating results’ minor dependence from the selected element size.The model accuracy has been confirmed by comparing the obtained results against experimental and benchmark data from the literature. The size effect study demonstrated a decrease in maximum stress of the open-hole laminates in compression with increasing specimen in-plane size. This trend is consistent with experimental and reference numerical observations, confirming the model accuracy and applicability even for relatively coarse meshes. Therefore, computational efficiency is improved, with preserved accuracy of conventional solid finite element models.

Semi-Supervised Left-Atrial Segmentation Based on Squeeze–Excitation and Triple Consistency Training

Convolutional neural networks (CNNs) have achieved remarkable success in fully supervised medical image segmentation tasks. However, the acquisition of large quantities of homogeneous labeled data is challenging, making semi-supervised training methods that rely on a small amount of labeled data and pseudo-labels increasingly popular in recent years. Most existing semi-supervised learning methods, however, underestimate the importance of the unlabeled regions during training. This paper posits that these regions may contain crucial information for minimizing the model’s uncertainty prediction. To enhance the segmentation performance of the left-atrium database, this paper proposes a triple consistency segmentation network based on the squeeze-and-excitation mechanism (SETC-Net). Specifically, the paper constructs a symmetric architectural unit called SEConv, which adaptively recalibrates the feature responses in the channel direction by modeling the inter-channel correlations. This allows the network to adaptively weigh each channel according to the task’s needs, thereby emphasizing or suppressing different feature channels. Moreover, SETC-Net is composed of an encoder and three slightly different decoders, which convert the prediction discrepancies among the three decoders into unsupervised loss through a constructed iterative pseudo-labeling scheme, thus encouraging consistent and low-entropy predictions. This allows the model to gradually capture generalized features from these challenging unmarked regions. We evaluated the proposed SETC-Net on the public left-atrium (LA) database. The proposed method achieved an excellent Dice score of 91.14% using only 20% of the labeled data. The experiments demonstrate that the proposed SETC-Net outperforms seven current semi-supervised methods in left-atrium segmentation and is one of the best semi-supervised segmentation methods on the LA database.

Numerical Simulation Method for the Aeroelasticity of Flexible Wind Turbine Blades under Standstill Conditions

With the trend towards larger and lighter designs of wind turbines, blades are progressively being developed to have longer and more flexible configurations. Under standstill conditions, the separated flow induced by a wide range of incident flow angles can cause complex aerodynamic elastic phenomena on blades. However, classical momentum blade element theory methods show limited applicability at high angles of attack, leading to significant inaccuracies in wind turbine performance prediction. In this paper, the geometrically accurate beam theory and high-fidelity CFD method are combined to establish a bidirectional fluid–structure coupling model, which can be used for the prediction of the aeroelastic response of wind turbine blades and the analysis of fluid–structure coupling. Aeroelastic calculations are carried out for a single blade under different working conditions to analyze the influence of turbulence, gravity and other parameters on the aeroelastic response of the blade. The results show that the dominant frequency of the vibration deformation response in the edgewise direction is always the same as the first-order edgewise frequency of the blade when the incoming flow condition is changed. The loading of gravity will make the aeroelastic destabilization of the blade more significant, which indicates that the influence of gravity should be taken into account in the design of the aeroelasticity of the wind turbine. Increasing the turbulence intensity will change the dominant frequency of the vibration response in the edgewise direction, and at the same time, it will be beneficial to the stabilization of the aeroelasticity response.

Elasto-plastic material model of green beech wood

Physically modelling the mechanical response of a tree by numerical simulation depends on having accurate data on the mechanical properties of green hardwood. Lacking such data, we developed and validated an orthotropic elasto-plastic (E–P) material model, based on the results of experiments performed on European beech (Fagus sylvatica L.) green wood, capable of including both the non-linearity and orthotropic properties of the material. We selected 655 clear samples with the special orthotropic structure of annual rings. All samples were prepared immediately after felling; their moisture content (MC) was 80% on average. The mechanical responses in normal directions and shear are represented by bi-linear stress–strain curves. The E–P model was validated by comparing the force–deflection response of three-point bending of green wood samples in a finite-element method (FEM) simulation (the average relative error was 4.6% for point-wise and 1.7% for integral-wise comparison). The output of this work was a consistent set of material constants for the E–P material model that is now available for the structural analysis of beech wood with MC above to fibre saturation point (FSP), especially green wood, subjected to relatively high loads (such that a plastic deformation appears) and that can very well predict a non-linear response above the proportional limits.

Wind-Induced Response Analysis and Fatigue Life Prediction of a Hybrid Wind Turbine Tower Combining an Upper Steel Tube with a Lower Steel Truss

Based on the WindPACT-3MW wind turbine tower commonly used in wind power engineering, a finite element model (FEM) of a hybrid wind turbine tower combining an upper steel tube with a lower steel truss is designed and established. On this basis, a static optimization analysis, wind-induced vibration analysis, and fatigue life analysis of the hybrid tower structure are performed. The results show that under the same design parameters, the overall stiffness and static bearing capacity of the tower structure can be significantly improved by using subdivided truss webs, increasing the truss height as much as possible and increasing the width of the truss base appropriately. Under normal operation conditions, the response of the tower structure in the along-wind direction is significantly greater than the response in the crosswind direction, indicating that the aerodynamic thrust generated by the rotation of the blades is the main factor causing the wind-induced vibration of the tower structure. For the tower structure analyzed in this study, when considering the entire range of wind speeds from the cut-in wind speed to the cut-out wind speed, the fatigue life of the structure is 38.5 years.

Experimental investigation on fluid-induced vibration of a semi-submerged flexible pipe in oncoming flows

Fluid-induced vibration (FIV) features of the semi-submerged flexible pipe in an oncoming flow are experimentally investigated in this paper. The flexible pipe is towed to simulate the equivalent uniform oncoming flow with a Froude number (Fr) ranging from 0.2 to 2.5. The overtopping states are determined and divided into three regions by the Fr numbers, including non-overtopping, intermitting overtopping, and continuous overtopping regions. Through the displacement reconstruction and wavelet transform methods, the displacement response, frequency, trajectory, and the chaotic characteristics of the semi-submerged pipe are studied. The results show that the FIV displacement responses are evidently affected by the intensity of the overtopping phenomenon. A significant mean displacement in the cross flow (CF) direction can be seen and a maximum value of 0.88D can be reached. The unexpectedly larger FIVs with standard deviation values of around 0.52D can be witnessed in the in-line (IL) direction than those for a fully submerged pipe. Moreover, the FIV frequency response in the IL direction is found to be consistent with that in the CF direction under intermitting overtopping and continuous overtopping state, and the corresponding Strouhal numbers are 0.24 and 0.28, respectively. The FIV response is found to be chaotic in non-overtopping states, while it behaves periodic and quasiperiodic features as overtopping occurs. The “O” shape of the motion trajectory is observed at such overtopping regions. The present work improves the basic understanding of the FIV features of the semi-submerged flexible pipe in the oncoming flow and can provide useful references for designing the relevant marine structures.

Anisotropic power-law viscoelasticity of living cells is dominated by cytoskeletal network structure

During physiological and pathological processes, cells experience significant morphological alterations with the re-arrangement of cytoskeletal filaments, resulting in anisotropic viscoelasticity. Here, a structure-based cell model is proposed to study the anisotropic viscoelastic mechanical behaviors of living cells. We investigate how cell shape affects its creep responses in longitudinal and perpendicular directions. It is shown that cells exhibit power-law rheological behavior in both longitudinal and perpendicular directions under step stress, with a more solid-like behavior along the longitudinal direction. We reveal that the cell volume and cytoskeletal filament orientation, which have been neglected in most existing models, play a critical role in regulating cellular anisotropic viscoelasticity. The stiffness of the cell in both directions increases linearly with increasing its aspect ratio, due to the decrease of cell volume. Moreover, the increase in the cell's aspect ratio produces the aggregation of cytoskeletal filaments along the longitudinal direction, resulting in higher stiffness in this direction. It is also shown that the increase in cell's aspect ratio corresponds to a process of cellular ordering, which can be quantitatively characterized by the orientational entropy of cytoskeletal filaments. In addition, we present a simple yet robust method to establish the relationship between cell's aspect ratio and cell volume, thus providing a theoretical framework to capture the anisotropic viscoelastic behavior of cells. This study suggests that the structure-based cell models may be further developed to investigate cellular rheological responses to external mechanical stimuli and may be extended to the tissue scale. Statement of significanceThe viscoelastic behaviors of cells hold significant importance in comprehending the roles of mechanical forces in embryo development, invasion, and metastasis of cancer cells. Here, a structure-based cell model is proposed to study the anisotropic viscoelastic mechanical behaviors of living cells. Our study highlights the crucial role of previously neglected factors, such as cell volume and cytoskeletal filament orientation, in regulating cellular anisotropic viscoelasticity. We further propose an orientational entropy of cytoskeletal filaments to quantitatively characterize the ordering process of cells with increasing aspect ratios. Moreover, we derived the analytical interrelationships between cell aspect ratio, cell stiffness, cell volume, and cytoskeletal fiber orientation. This study provides a theoretical framework to describe the anisotropic viscoelastic mechanical behavior of cells.

Survey on Context Based Identification of Customer Name Variations using ML Techniques

Abstract: The demand for automated validation of new customer company accounts, with a specific emphasis on resolving name variations within large databases, is steadily increasing. This surge in demand is a direct response to the significant scale at which data for new customers is being input into CRM systems, necessitating manual validation and correction processes. The primary objective of this survey paper is to identify machine learning methods capable of addressing the challenge of resolving name variations in extensive databases. To achieve this goal, we propose a multi-step approach. Firstly, we employ an approximate string matching algorithm with high computational speed to identify matches with a very high percentage of accuracy. In cases where such matches are not found in the system, we utilize named entity recognition techniques to annotate company names and their suffixes, such as INC, PVT, LTD, CORP, and CO, which may appear in various forms. To resolve abbreviation disambiguity, we explore the application of machine learning algorithms, including the naïve Bayes classifier, decision trees, and Support Vector Machines. In this survey paper, we conclude by presenting potential approximate string matching algorithms, a named entity recognition method, and a model for resolving abbreviation disambiguity. Our review not only provides a comprehensive overview of the current state of research in this area but also highlights gaps in the existing knowledge, offering valuable insights for future research and practical application.

Effect of MnO2-biochar composites on promoting humification during chicken manure composting

The present study aimed to accelerate the humification and to investigate how MnO2 modification of biochar (MBC) drives the humus formation during composting with chicken manure. In this study, compared with the control group (CK), the addition of MBC caused an increase in the concentration of both humus and humic acid (HA), with a respective enhancement of 29.1% and 37.2%. In addition, MBC also improved the stability of compost products. Hetero two-dimensional correlation spectra further exhibited that the MBC could alter the formation mechanism of humus fractions during composting. Random forest analysis showed that Microbacterium, Bacteroides, Kroppenstedtia, Gracilibacillus, and Lentibacillus were significantly related to humus formation (P < 0.05). MBC enhanced the absolute abundance of these five genera during composting. The structural equation model further confirmed that these five genera could be indirectly involved in humus formation, through the production of aromatic compounds via secondary metabolism. Additionally, these five genera could directly transform organic components into macromolecular humus structures. Therefore, the increase in these five genera might be a direct response to the acceleration of the humification during MBC composting. These findings demonstrate the potential value of MBC in harmless disposal of hazardous biowastes through composting.HighlightsMnO2 modification of biochar changed the formation mechanism of humus fractions.Key genera involved in humus formation were identified.Among of MnO2 modification of biochar, key genera and humus formation were revealed.Graphical

SARS-CoV-2 infection of endothelial cells, dependent on flow-induced ACE2 expression, drives hypercytokinemia in a vascularized microphysiological system.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for COVID-19, has caused nearly 7 million deaths worldwide. Severe cases are marked by an aggressive inflammatory response known as hypercytokinemia, contributing to endothelial damage. Although vaccination has reduced hospitalizations, hypercytokinemia persists in breakthrough infections, emphasizing the need for disease models mimicking this response. Using a 3D microphysiological system (MPS), we explored the vascular role in SARS-CoV-2-induced hypercytokinemia. The vascularized micro-organ (VMO) MPS, consisting of human-derived primary endothelial cells (ECs) and stromal cells within an extracellular matrix, was used to model SARS-CoV-2 infection. A non-replicative pseudotyped virus fused to GFP was employed, allowing visualization of viral entry into human ECs under physiologic flow conditions. Expression of ACE2, TMPRSS2, and AGTR1 was analyzed, and the impact of viral infection on ACE2 expression, vascular inflammation, and vascular morphology was assessed. The VMO platform facilitated the study of COVID-19 vasculature infection, revealing that ACE2 expression increased significantly in direct response to shear stress, thereby enhancing susceptibility to infection by pseudotyped SARS-CoV-2. Infected ECs secreted pro-inflammatory cytokines, including IL-6 along with coagulation factors. Cytokines released by infected cells were able to activate downstream, non-infected EC, providing an amplification mechanism for inflammation and coagulopathy. Our findings highlight the crucial role of vasculature in COVID-19 pathogenesis, emphasizing the significance of flow-induced ACE2 expression and subsequent inflammatory responses. The VMO provides a valuable tool for studying SARS-CoV-2 infection dynamics and evaluating potential therapeutics.

Student Creativity in Developing Interactive Multimedia Using Kodular for Junior High School Mathematics Learning

This research is qualitative research that aimed to investigate the results of the development of learning media by students to improve school students' creative performance and students' creative thinking using the Kodular application. This study focuses on the problem of the lack of learning media at the junior high school level which is used as a means of independent learning for students at home. The subject was a class of The Department of Mathematics Education. The research subjects were 41 students in the department of mathematics education. data were taken using observation and documentation techniques that were adapted to mathematical creative thinking indicators. Interactive multimedia developed by students in the form of mathematical material presented in text form, containing equations, screenshots of graphics from the Desmos application, and video explanations of the material. Furthermore, practice questions and post-tests are presented using the help of Google Form, Quizziz, and Liveworksheets so that users get a direct response to the answers to the questions so that they meet the interactive characteristics of the learning media. The results obtained are 41 students are able to develop interactive multimedia that is run through an android application in junior high school mathematics learning. Creative thinking skills are achieved by using the dimensions of fluency, flexibility, and originality. This is achieved from media development carried out by students The creative performance of students reaches the usefulness dimension but has not been able to reach the novelty of the interactive multimedia that has been developed.

Energy extraction and optimization studies on vortex-induced vibration of the elastically mounted rigid cylinder using wake oscillator model

The vortex-induced vibration (VIV) response of an elastically mounted rigid cylinder from the standpoint of energy harvesting is analyzed with the aid of the wake oscillator model (WOM). A model of an elastically mounted rigid cylinder free to oscillate in the in-line (IL) and cross-flow (CF) directions subjected to different uniform flow velocities is considered and its responses under different mass ratios are predicted using the modified wake oscillator model. For modeling structure motion, the dynamic equilibrium equation, and for modeling the fluid part, the Van der Pol wake oscillator is utilized and they are coupled together to get the response in IL and CF directions. A comparative study is performed between the numerical and the experimental results and they are found to be in good agreement. The study is then probed into the scope of energy extraction from VIV which will presumably throw light into the development of VIV-based energy harvesting methods which is a potential future hope for the renewable energy sector. Parametric optimization study is carried out to determine the maximum harnessable energy from VIV. The response of the cylinder for the optimal parametric combination is analyzed in the time and frequency domain. It is observed that damping and reduced velocity play a crucial role in the energy extraction.

European Summer Wet-Bulb Temperature: Spatiotemporal Variations and Potential Drivers

Abstract Heat stress is projected to intensify with global warming, causing significant socioeconomic impacts and threatening human health. Wet-bulb temperature (WBT), which combines temperature and humidity effects, is a useful indicator for assessing regional and global heat stress variability and trends. However, the variations of European WBT and their underlying mechanisms remain unclear. Using observations and reanalysis datasets, we demonstrate a remarkable warming of summer WBT during the period 1958–2021 over Europe. Specifically, the European summer WBT has increased by over 1.0°C in the past 64 years. We find that the increase in European summer WBT is driven by both near-surface warming temperatures and increasing atmospheric moisture content. We identify four dominant modes of European summer WBT variability and investigate their linkage with the large-scale atmospheric circulation and sea surface temperature anomalies. The first two leading modes of the European WBT variability exhibit prominent interdecadal to long-term variations, mainly driven by a circumglobal wave train and concurrent sea surface temperature variations. The last two leading modes of European WBT variability mainly show interannual variations, indicating a direct and rapid response to large-scale atmospheric dynamics and nearby sea surface temperature variations. Further analysis shows the role of global warming and changes in midlatitude circulations in the variations of summer WBT. Our findings can enhance the understanding of plausible drivers of heat stress in Europe and provide valuable insights for regional decision-makers and climate adaptation planning. Significance Statement Wet-bulb temperature, which takes into account the combined effect of temperature and humidity, is a good indicator for assessing heat stress. In the context of global warming, heat stress is anticipated to escalate, posing significant risks to human health and causing socioeconomic losses. However, variations in wet-bulb temperature and the associated physical mechanisms have received limited attention. This study aims to improve our understanding of the temporal and spatial variations and the potential driving mechanisms of summer wet-bulb temperature across Europe in recent decades. We have observed a noteworthy increase in summer wet-bulb temperature, indicating a regional intensification of heat stress, particularly within the last 10 years. We further investigate the connections between variations in summer wet-bulb temperature, large-scale atmospheric circulation, and sea surface temperature. Additionally, we explore their associations with global warming and changes in midlatitude atmospheric circulation. The outcomes of this study not only contribute to establishing a scientific basis for evaluating heat-related risks in Europe but also facilitate preparedness for future climate adaptation and mitigation at both regional and local scales.

Models for the estimation of gust-buffeting response in symmetrical wind-sensitive structures

The peak factor is an analytical development for estimating the expected maximum response caused by aerodynamic forces on wind-sensitive structures. It expresses the likelihood of how above the mean is the maximum amplitude of a stationary process in terms of its standard deviation. Such a process represents the structural response of a wind-sensitive structure in conventional applications. The methods and solutions used to approximate it in the along-wind direction have become ordinary to structural engineers. Notwithstanding, the structural response in combined orthogonal directions is often omitted since a criterion for such an estimation is still absent. This communication seeks to contribute to fill the gap in practical criteria for estimating response maxima in symmetric structures. It is done by proposing models to estimate the parameters describing the probability distribution of the maxima from the Euclidean norm of two correlated Gaussian variables. Although the applications to structural engineering are emphasized, the proposed models apply to other problems where the maxima from the norm of two Gaussian variables is relevant.

Terahertz structured deep-subwavelength plasmonic grating metasurface for manipulating polarization-dependent coupling response

The complex electromagnetic anisotropy of terahertz (THz) metasurfaces with geometric symmetry breaking has attracted extensive attention. Typical effects arise from the coupling of polarization responses in orthogonal directions of various components of the metasurface structure, such as the electromagnetically induced transparency (EIT) effect. However, it is a challenge to precisely control or perfectly avoid the polarization-dependent coupling responses. In this work, deep-subwavelength plasmonic gratings (PGs) with a fine wire width of 1 μm at the order of deep subwavelengths of 1/100 THz wave are fabricated by electron beam lithography, and these wire gratings are graphically designed as a C-shaped metasurface pattern with a period of 100 μm in sub-wavelength scale. The complete anisotropic response in the single-oriented PG metasurface is demonstrated by both simulation and experiments, where the polarization-dependent coupling effect is eliminated. More interestingly, the hybrid-oriented PG metasurface exhibits narrowband and wideband EIT effects in the x and y polarization directions with the maximum polarization extinction ratio of 20 dB, respectively, indicating this mechanism can realize more flexible manipulation of polarization-dependent coupling. This patterned deep-subwavelength PG provides a new structure and mechanism for excitation, regulation, and restriction of polarization-dependent mode coupling, and has important applications in THz spectroscopic detection, polarization imaging, and wireless communication.