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Substrate composition has been widely recognised as a primary variable shaping lotic macroinvertebrate communities at the habitat unit level. However, fundamental understanding of how communities inhabiting mineralogical habitats (i.e., gravel, sand and silt) are structured across differing rivers is lacking. Moreover, research largely focusses on gravel beds and fine sediment in general (<2 mm) and as a result detailed field observations specifically of the sand and silt fractions are lacking. Using data from five UK streams collated from published studies, we assess taxonomic and functional biodiversity (alpha and beta diversity) at the habitat unit level (as defined by substrate composition of sand, silt and gravel). We found that the composition of taxonomic communities were clearly different in all habitat units for each individual stream (and at the landscape scale), with comparable, but less strong, distinctions between substrates for functional macroinvertebrate community composition. However, alpha diversity metrics and Local Contribution to Beta Diversity (LCBD) recorded among the different habitat units varied significantly across individual rivers, and the amount of variation explained by the habitat unit for taxonomic and functional composition demonstrated considerable differences suggesting strong context dependence. The depositional fine sediment habitats of sand and silt were found to support a discrete community composition and differing levels of alpha and beta diversity within and between rivers. We advocate that care should be taken when seeking to generalise biodiversity patterns at a landscape scale as our study highlights the high degree of context dependency when considering the role of the habitat template. Moreover, our results provide evidence that discriminating between the size fractions of fine sediment habitats (sand or silt) is important to fully elucidate the wider ecological importance of these habitats and the distinct taxonomic and functional biodiversity they support. [ABSTRACT FROM AUTHOR]

Accurate description of concrete crack propagation is of great significance to practical engineering. This paper adopts the cohesive zone model (CZM) to investigate both the macro‑mechanical properties and the micro‑cracking damage behavior of concrete beams in a three-point bending test. Throughout the study of damage under loading in the three-point bending test, parametric examinations are conducted on five key factors controlling the cracking of cohesive elements regarding the case of circulate aggregate, namely type I fracture energy, type II fracture energy, shear strength, tensile strength and elastic modulus (stiffness). Through the test results of macro-mechanical properties and micro-cracking, the test results of a group of specimens and the results of parametric models are reversely analyzed, and the applicable parameter range of control factors in three-point bending simulation is obtained. Three computation models with different aggregate areas are established by taking account of the quantitative aggregate data from specimens with different mix proportions. The parameter range is then applied to derive quantitative results related to crack propagation. Eventually, the accuracy of the parameter range is validated against both the mechanical properties and quantitative crack data obtained from simulations and experiment. [ABSTRACT FROM AUTHOR]

Various factors influence wildfire probability, including land use/land cover (LULC), fuel types, and their moisture content, meteorological conditions, and terrain characteristics. The Adriatic Sea coastal area in Croatia has a long record of devastating wildfires that have caused severe ecological and economic damages as well as the loss of human lives. Assessing the conditions favorable for wildfires and the possible damages are crucial in fire risk management. Adriatic settlements and ecosystems are highly vulnerable, especially during summer, when the pressure from tourist migration is the highest. However, available fire risk models designed to fit the macro-scale level of assessment cannot provide information detailed enough to meet the decision-making conditions at the local level. This paper describes a model designed to assess wildfire risks at the meso-scale, focusing on environmental and anthropogenic descriptors derived from moderate- to high-resolution remote sensing data (Sentinel-2), Copernicus Land Monitoring Service datasets, and other open sources. Risk indices were integrated using the multi-criteria decision analysis method, the analytic hierarchy process (AHP), in a GIS environment. The model was tested in three coastal catchments, each having recently experienced severe fire events. The approach successfully identified zones at risk and the level of risk, depending on the various environmental and anthropogenic conditions. [ABSTRACT FROM AUTHOR]

Urban infrastructure development is one principal way people are transforming the natural world and their living conditions. It is important for humanity, but it can also cause major impacts to the environment, such as huge amounts of solid waste and CO2 emissions. Considering this, the circular economy (CE) is a promising alternative to the traditional “make, use, and dispose” linear economy model. However, as a strategy for sustainable development (SD), the CE is still in its infancy in the urban transport infrastructure sector. Therefore, this article aims to guide the implementation of CE during transport infrastructure projects. To achieve this goal, a literature review and case study were adopted as the research methods. After reviewing existing well-established CE frameworks, the iReSOLVE (implement, Regenerate, Share, Optimize, Loop, Virtualize, Exchange) framework is recognized as the most comprehensive one. Upon it, an analytical framework containing specific-related aspects of CE in urban transport infrastructure projects (which belongs to meso-scale) is proposed (coined as the 4Wh-iReSOLVE framework). The 4Wh means Who, When, Where, and What. The proposed framework offers insight into potential CE activities for transport infrastructure projects and assists in assessing the performance and impacts of CE of these projects to cover the gap of the neglected meso-scale. Ten circular viaduct project initiatives in the Netherlands are used as case analyses with the 4Wh-iReSOLVE framework. The results present the highlights of the circular viaduct initiatives in the Netherlands, with CE activities categorized into five groups (design-related strategies, general CE strategies, implementation, management, and related digital technologies and materials, as well as environmental sustainability). As verified by several experts of the projects studied, it can be concluded that the 4Wh-iReSOLVE framework is suitable for transport infrastructure project CE analyses and implementations. It can potentially be a suggested guideline in future policy documents.

The Central Business Districts (CBDs) of Dhaka are characterized by heavy traffic congestion, air pollution and peak office hour commuting density. Pedestrian-friendly environment is crucial for accessing the CBDs as it reduces auto-mobile dependency and encourages transit use. As of now, no research has assessed the walkability of Dhaka’s CBDs considering meso-scale factors such as land use diversity, density, street connectivity and micro-scale factors such as footpath continuity and quality, accessibility, safety, security, amenity and comfort of the streets. This paper evaluates the built environment attributes of total 15 wards across core CBDs of Dhaka North City Corporation (DNCC) and Dhaka South City Corporation (DSCC): Motijheel, Karwan Bazar, Mohakhali, Gulshan-Banani, and Mirpur to objectively assess walkability at both meso and micro scales. At meso-scale, a walkability index is generated that categorizes the wards into the most and least walkable using GIS, with Mirpur DNCC Ward-03 identified as the most walkable and Motijheel DSCC Ward-08 as the least walkable. At micro-scale, the walking environments in Mirpur Ward-03 and Motijheel Ward-08 are assessed based on Multi-Criteria Decision-Making (MCDM) approach. Results reveal several challenges such as narrow and discontinuous footpaths, presence of multiple barriers including utility poles, pillars, trees and, limited accessibility in Mirpur Ward-03 and garbage dumping, illegal car parking, haphazard hawker encroachments in Motijheel Ward-08. Our findings identify targeted areas needing improvement to enhance overall pedestrian-friendliness of the CBDs. The methodology followed in this study could be applied to evaluate the walkability of CBDs worldwide.

Abstract Background With the generation of vast compendia of biological datasets, the challenge is how best to interpret ‘omics data alongside biochemical and other small-scale experiments to gain meaningful biological insights. Key to this challenge are computational methods that enable domain-users to generate novel hypotheses that can be used to guide future experiments. Of particular interest are flexible modeling platforms, capable of simulating a diverse range of biological systems with low barriers of adoption to those with limited computational expertise. Results We introduce Cell4D, a spatial-temporal modeling platform combining a robust simulation engine with integrated graphics visualization, a model design editor, and an underlying XML data model capable of capturing a variety of cellular functions. Cell4D provides an interactive visualization mode, allowing intuitive feedback on model behavior and exploration of novel hypotheses, together with a non-graphics mode, compatible with high performance cloud compute solutions, to facilitate generation of statistical data. To demonstrate the flexibility and effectiveness of Cell4D, we investigate the dynamics of CEACAM1 localization in T-cell activation. We confirm the importance of Ca2+ microdomains in activating calmodulin and highlight a key role of activated calmodulin on the surface expression of CEACAM1. We further show how lymphocyte-specific protein tyrosine kinase can help regulate this cell surface expression and exploit spatial modeling features of Cell4D to test the hypothesis that lipid rafts regulate clustering of CEACAM1 to promote trans-binding to neighbouring cells. Conclusions Through demonstrating its ability to test and generate hypotheses, Cell4D represents an effective tool to help integrate knowledge across diverse, large and small-scale datasets.

This article deals with damage simulations of three-dimensional (3D) textile stitched composites under compression loading at meso-scale. The 3D fabric geometry is created by experimental geometry measurements based on textile fiber microscopic images. At first, if a meso-scale of 3D unit-cell of the stitched composite is drawn in Catia software, then the model is imported into Abaqus finite element (FE) software. In addition, a Fortran code is prepared and linked to the Abaqus FE software for computing the stitched composite's mechanical coefficient. Finally, a user-defined subroutine in the finite element implements the damage model to anticipate the stitched composite's damage initiation and growth. The results of FE modeling show good agreement with the experimental results. This research could contribute the investigation of the integrity and damage tolerance of 3D-stitched composites for aerospace structures. [ABSTRACT FROM AUTHOR]

This paper proposes a finite element (FE) analysis approach in meso-scale to predict the mechanical behavior, including elastic moduli and tensile strength, of SiC nanowires reinforced aluminum matrix (SiCnw/Al) composites. The study investigates the influence of the volume fraction and the aspect ratio of the SiC nanowires on the mechanical properties of the composites by employing the representative volume elements (RVE) models. The FE results successfully predict the elastic moduli and strength properties of the SiCnw/Al composites, exhibiting consistency with both the experimental findings and the theoretical predictions. In terms of microstructure, the elastic moduli and strength of the composites generally exhibit an increasing trend with higher volume fractions. However, the aspect ratio demonstrates a more intricate behavior, initially increasing and eventually reaching a saturation value as the aspect ratio increases. The results also reveal significant effects of the extrusion treatment on the mechanical properties of the SiCnw/Al composites, leading to an increase in the elastic moduli and strength along the direction of the nanowires. The numerical approach presented in this work provides an accurate means of predicting the mechanical properties of SiCnw/Al composites, thereby serving as a valuable reference for designers. [ABSTRACT FROM AUTHOR]

Background: With the generation of vast compendia of biological datasets, the challenge is how best to interpret 'omics data alongside biochemical and other small-scale experiments to gain meaningful biological insights. Key to this challenge are computational methods that enable domain-users to generate novel hypotheses that can be used to guide future experiments. Of particular interest are flexible modeling platforms, capable of simulating a diverse range of biological systems with low barriers of adoption to those with limited computational expertise. Results: We introduce Cell4D, a spatial-temporal modeling platform combining a robust simulation engine with integrated graphics visualization, a model design editor, and an underlying XML data model capable of capturing a variety of cellular functions. Cell4D provides an interactive visualization mode, allowing intuitive feedback on model behavior and exploration of novel hypotheses, together with a non-graphics mode, compatible with high performance cloud compute solutions, to facilitate generation of statistical data. To demonstrate the flexibility and effectiveness of Cell4D, we investigate the dynamics of CEACAM1 localization in T-cell activation. We confirm the importance of Ca2+ microdomains in activating calmodulin and highlight a key role of activated calmodulin on the surface expression of CEACAM1. We further show how lymphocyte-specific protein tyrosine kinase can help regulate this cell surface expression and exploit spatial modeling features of Cell4D to test the hypothesis that lipid rafts regulate clustering of CEACAM1 to promote trans-binding to neighbouring cells. Conclusions: Through demonstrating its ability to test and generate hypotheses, Cell4D represents an effective tool to help integrate knowledge across diverse, large and small-scale datasets. [ABSTRACT FROM AUTHOR]

Walking as one type of physical activity generates benefits for personal health and contributes to sustainability in its environmental, economic, and social dimensions. Based on a cross-sectional survey for a representative sample of German cities with at least 100,000 residents, this study investigates determinants of residents' walking behavior. Two contexts of promenading in the city for leisure walking and the trip to the supermarket for utilitarian walking are distinguished in order to investigate differences in respondents' perceived importance of built-environment characteristics and to bridge the gap between the individual level of residents' behavior and the streetscape level. In addition, the analyses distinguish between frequent and less frequent walkers in order to understand differences in characteristics, behavior, preferences, and perceptions between these two groups. The results of this study with a sample of n = 4,637 respondents show that the relevance of the built environment is higher for leisure walking than for utilitarian walking and higher for frequent walkers compared to less frequent walkers. For leisure walking, "protection"-variables are ranked high (e.g. safety, security), followed by "comfort" (e.g. space, surface quality) and by "delight" (e.g. attractive buildings, greenery). Distance is key for utilitarian walking. Significant differences between frequent and less frequent walkers are identified mainly for the "Delight"-variables, this is attractive buildings and greenery for utilitarian walking, and space availability and street furniture for leisure walking. These differences should be considered in future research and street design practice which might preferably focus on the most demanding person group of frequent walkers. [ABSTRACT FROM AUTHOR]

Abstract Substrate composition has been widely recognised as a primary variable shaping lotic macroinvertebrate communities at the habitat unit level. However, fundamental understanding of how communities inhabiting mineralogical habitats (i.e., gravel, sand and silt) are structured across differing rivers is lacking. Moreover, research largely focusses on gravel beds and fine sediment in general (

A new computational framework is developed in this paper for investigating the time-dependent behaviour of concrete including creep, shrinkage and cracking. The developed model aims to explain certain aspects of the time-dependent cracking and creep of concrete that cannot be captured using homogeneous models. The model is based on the scaled boundary finite element method, and it is coupled with a quadtree decomposition algorithm which converts digital images of concrete meso-structures into meshes. Concrete is treated as a two-phase composite which consists of elastic aggregates and mortar that is subjected to time-dependent deformation. The basic creep behaviour is treated as viscoelastic, which is modelled based on a rate-type rheological model corresponding to a Kelvin chain. Drying creep is modelled using a viscous unit which depends on the stress level, and drying shrinkage is stress independent. Both drying creep and drying shrinkage are related to the internal humidity. The humidity distribution within concrete is determined using a diffusion analysis. The moisture movement within mortar is governed by a nonlinear diffusion equation, whereas the aggregates are assumed impermeable. The cracking of concrete is explicitly modelled on the meso-scale through coupling of the continuum damage model for cracking within the mortar phase, and the cohesive zone model for debonding between aggregates and mortar. The proposed model is verified by simulating well-documented experimental studies in the literature. The capability of the proposed model in simulating the time-dependent behaviour of concrete and capturing the crack patterns has also been demonstrated. [ABSTRACT FROM AUTHOR]

Various factors influence wildfire probability, including land use/land cover (LULC), fuel types, and their moisture content, meteorological conditions, and terrain characteristics. The Adriatic Sea coastal area in Croatia has a long record of devastating wildfires that have caused severe ecological and economic damages as well as the loss of human lives. Assessing the conditions favorable for wildfires and the possible damages are crucial in fire risk management. Adriatic settlements and ecosystems are highly vulnerable, especially during summer, when the pressure from tourist migration is the highest. However, available fire risk models designed to fit the macro-scale level of assessment cannot provide information detailed enough to meet the decision-making conditions at the local level. This paper describes a model designed to assess wildfire risks at the meso-scale, focusing on environmental and anthropogenic descriptors derived from moderate- to high-resolution remote sensing data (Sentinel-2), Copernicus Land Monitoring Service datasets, and other open sources. Risk indices were integrated using the multi-criteria decision analysis method, the analytic hierarchy process (AHP), in a GIS environment. The model was tested in three coastal catchments, each having recently experienced severe fire events. The approach successfully identified zones at risk and the level of risk, depending on the various environmental and anthropogenic conditions.

The precise prediction of moisture variations within concrete is of great significance because various deterioration phenomena spanning corrosion to carbonation are induced by mass transfer facilitated by the presence of moisture. Under actual environmental conditions, concrete is exposed to numerous wetting and drying cycles. Thus, to accurately predict moisture variations it is essential to consider the effect of these conditions. This study investigates the effect of alternate wetting and drying cycles on moisture penetration through concrete at the mesoscale using a 3D discrete network model based on a Rigid Body Spring Model (RBSM). For modeling moisture transport during wetting, the non-linear diffusion equation is used and the effects of capillary suction in moisture transport are also considered. On the other hand, moisture transport during drying is modeled as an evaporation-diffusion process. The simulation results obtained using this discrete network model are validated against the available experimental outcomes. During the wetting cycle, the moisture content in regions close to the exposed surface rapidly increases and approaches the maximum saturation. The effect of subsequent drying is seen only until a certain depth below the exposed surface, known as the influential depth. It is also observed that moisture continues to penetrate deeper into a specimen even during a drying cycle.

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Air leakage in goaf is one of the main reasons for spontaneous combustion of residual coal. However, under different research scales, the gas flow in goaf follows different laws. In this paper, the velocity and pressure distribution of steady-state flow field in free flow domain and porous media domain in goaf are studied by using multi-scale correlation analysis method from macro scale and meso scale respectively. The heat flow moisture multi-field coupling model is constructed, and on this basis, the change of moisture in coal under the influence of gas flow and thermal evaporation is simulated by using multi-physical field simulation software. The results show that the moisture content in coal will gradually decrease under the effect of thermal evaporation, which is consistent with the results of thermogravimetric experiment. The concentration of water vapor on the leeward side is higher affected by the flow field. In addition, under the influence of evaporation and heat absorption, the temperature distribution of coal body will change continuously, and the internal temperature of coal body near the leeward side decreases slowly.

Concrete canvas rolls have several unique properties have made it a strategic material. A major property is rapidness of installation that can be considered in the construction of accelerated shelters of protection against threats. The use of concrete canvas in the construction of the shelter is also expanding worldwide due to its economic benefits and the speed of its installation, as experience has shown that a two-person team can build a shelter with an area of 25 square meters of concrete canvas in less than an hour. Increasing attention to this function of concrete canvas requires studying product behavior against incoming loads, and the need for a deep understanding of the material and components of aerated concrete leads to a better understanding of this product and the possibility of improving product quality. Therefore, the properties of two-phase concrete canvas, including fabric and mortar that have structural performance, were studied using Abacus finite element software. The results of finite element simulation on macro and Meso scales were compared with the laboratory results of different samples, showing the accuracy of the study. The results illustrate that the use of fibers with higher tensile strength and high Young's modulus and stiffness has a better performance against the applied loads. The shelter behavior is evaluated against different probable attack scenarios. The designed shelter is capable of withstanding slag up to a height of 70 cm of soil, which also makes it resistant to mortar attacks. The use of a concrete canvas shelter without any slag also makes it resistant to the 5 kg TNT threat at a distance of 3 meters. Using products against larger threats or loads strengthens the shell with appropriate materials or several layers of concrete canvas shells.

A micro-meso-scale model is proposed to predict shear deformation and strength of textile-reinforced composites, considering shear non-linearity, strain-rate dependent elastic and visco-plastic behavior, and 3D geometrical nonuniformity of the reinforcement. The matrix and fibers are combined using bridging-model micromechanics into composite tows. Combined with the geometrical characteristics of the reinforcement, a composite with orthotropic rate-dependent visco-plastic behavior is obtained. A damage model detects damage in the composite tows and interstitial matrix, introducing stiffness reduction and stress redistribution. The model constants are measured by experiments on neat epoxy matrix and unidirectional glass/epoxy specimens. Model predictions are validated with independent experiments. [ABSTRACT FROM AUTHOR]

Considering that the machining of composites particularly fiber-reinforced polymer composites (FRPCs) has remained a challenge associated with their heterogeneity and anisotropic nature, damage caused by drilling operations can be considerably mitigated by following optimum cutting parameters. In this work, we numerically evaluated the effects of cutting parameters, such as feed rate and spindle speed, on the thrust force and torque during the drilling of glass-fiber-reinforced polymers (GFRPs). A meso-scale, also known as unidirectional ply-level-based finite element modeling, was employed assuming an individual homogenized lamina with transversely isotropic material principal directions. To initiate the meso-scale damage in each lamina, 3D formulations of Hashin's failure theory were used for fiber damage and Puck's failure theory was implemented for matrix damage onset via user subroutine VUMAT in ABAQUS. The developed model accounted for the complex kinematics taking place at the drill–workpiece interface and accurately predicted the thrust force and torque profiles as compared with the experimental results. The thrust forces for various drilling parameters were predicted with a maximum of 10% error as compared with the experimental results. It was found that a combination of lower feed rates and higher spindle speeds reduced the thrust force, which in turn minimized the drilling-induced damage, thus providing useful guidelines for drilling operations with higher-quality products. Finally, the effect of coefficient of friction was also investigated. Accordingly, a higher coefficient of friction between the workpiece and drill-bit reduced the thrust force. [ABSTRACT FROM AUTHOR]

In addition to the normal service loadings, engineering structures may be subjected to occasional loadings such as earthquakes, which may cause severe destruction. When the steel rebar is corroded, the damage could be more serious. To investigate the seismic performance of corroded RC columns, a three-dimensional mesoscale finite element model was established. In this approach, concrete was considered as a three-phase composite composed of aggregate, mortar matrix and interfacial transition zone (ITZ). The nonlinear spring were used to describe the bond slip between steel and concrete. The degradation of the material properties of the steel rebar and cover concrete as well as the bonding performance due to corrosion were taken into account. The rationality of the developed numerical analysis model was verified by the good agreement between the numerical results and the available experimental observation. On this basis, the effect of corrosion level, axial force ratio and shear-span ratio on the seismic performance of corroded RC columns, including lateral bearing capacity, ductility, and energy consumption, were explored and discussed. The simulation results indicate that the mesoscopic method can consider the heterogeneity of concrete, to more realistically and reasonably reflect the destruction process of structures. [ABSTRACT FROM AUTHOR]

Chloride ion erosion is one of the main reasons for shortening the service life of concrete in marine and saline environment. Aggregate, as the largest raw material in concrete in volume proportion, is the main factor affecting the transport of chloride ion in concrete. In order to meet the demands of environmental protection and sustainable development, artificial lightweight aggregate and recycled aggregate have been widely used in concrete structures. Owing to the porous nature of lightweight aggregate and the complex interfacial transition zone of recycled aggregate, the chloride transport behavior in concrete prepared with these aggregates is obviously differ from those made with traditional aggregate. Therefore, it is particularly important to study the influence of aggregate on the transport behavior of chloride ions in concrete. This paper reviews the influence of aggregate on the chloride ion transport behavior, and summarizes the influence mechanisms of aggregate on the chloride ion transport t macro-and meso-scale. Finally, the existing problems in the current research were analyzed and the research prospects on chloride ion transport were presented. [ABSTRACT FROM AUTHOR]

Simple scaling analysis of terms in the Navier‐Stokes momentum equation for Earth's atmosphere suggests that winds at heights above 120 km should be smooth and laminar, with little spatial variation over horizontal scale lengths smaller than several hundred kilometers. However, there is increasing evidence that this traditional understanding may fail to account for several important processes, including both waves and small‐scale ion‐neutral momentum coupling. Here, we examine the thermospheric neutral wind field over Alaska in unprecedented detail using observations from an array of four ground‐based all‐sky imaging Fabry‐Perot interferometers, processed using a new geophysical inverse algorithm, to derive high‐resolution maps of all three wind components, with a temporal cadence of 30 seconds. The reconstructed high‐resolution neutral winds showed synoptic‐scale agreement with prior observations and previously validated techniques, with all results exhibiting behavior in agreement with basic physics. However, stacked time‐series plots of vector wind components reveal significantly more spatial and temporal structure than previously reported. In particular, the observed responses included complex wave‐like behavior and highly geographically variable vertical winds. Local flow features were observed at spatial scales as small as 100 km at times, with temporal scales as short as a few tens of minutes. Instances of close spatial and temporal correlations were observed between the wind fields reconstructed from green‐line spectra and ionospheric flows observed independently by SuperDARN. Key Points: Arrays of all‐sky viewing instruments obtain densely sampled Doppler remote sensing of thermospheric windsGeophysical inverse techniques are well suited for providing near‐optimal spatially resolved reconstructions of thermospheric windsMesoscale structures are directly observed in the thermosphere with length scales as low as 100 km [ABSTRACT FROM AUTHOR]

The models for textile structures based on the Finite Element Method (FEM) are diverse. In general, they can be divided into three groups based on their length scale: macro‐, meso‐, and micro‐scale models. The macro‐scale models are the simplest approach and require the least computational cost. On the contrary, the micro‐scale models are the most realistic and complex, thus involving extremely high computational costs. The meso‐scale models stand in the middle with sufficient representation degree at a reasonable computational cost. Every group of models has its own advantageous application field. For the forming process of 3D preforms, macro‐scale models have been widely used. As computational costs drop over time, meso‐scale models become more and more favorable. Hence, research efforts increasingly focus on meso‐scale models. In this paper, the modeling methods of FEM meso‐scale models for plain woven fabric made of glass roving and biaxial reinforced weft‐knitted fabric made of carbon fiber/polyamide 6.6 hybrid yarns are introduced. The experimental tests are used to characterize the mechanical properties of the yarns and fabrics. Different modeling methods for the geometries of each type of fabric are described. The mechanical behavior of the models is calibrated and validated with the help of a series of test simulations. Examples for the usage of the introduced models are presented. [ABSTRACT FROM AUTHOR]

Using MICAPS data, ERA-Interim 0.25°×0.25° global high resolution reanalysis data, hourly surface observation data, FY-2G satellite cloud picture and CR/CB radar data from Yulin, a comprehensive analysis was conducted for an extreme heavy storm rain event occurred in northern Shaanxi province from 20:00 BT 25 July to 08:00 BT 26 July 2017. The results are as follows. (1) The heavy precipitation event exhibited a clear east-west zonal distribution, with slow moving high rainfall during a long time period in a small area, and mainly concentrating at night. Typical beta mesoscale characteristics showed in areas of heavy rainfall. (2) The westerly trough moved rapidly eastward and pressed down to the south. The stable maintenance of western Pacific subtropical high pressure favored the strengthening of the positive vorticity advection in front of the trough and the development of a low-value system in the surface layer. The nascent Hetao vortex at 850 hPa and southeast low-level jet are the direct impact systems to this heavy precipitation event. (3) Hetao vortex is a shallow thermal low pressure system with three development stages. In the initial stage, a low vortex formed in weak zone with warm center of asymmetry structure. In the mature and vigorous phases, the vortex changed into symmetric warm center structure, and heavy rainfall starts in the mature stage and reaches peak in the vigorous stage. (4) Hetao vortex directly affects and controls the occurrence and development of mesoscale low pressure at the ground. Mesoscale low pressure is stable in the west of Yulin. Cold and warm convergence are formed in the west and east of the mesoscale low, respectively, which continuously trigger the generation of convective monomers.

Abstract The models for textile structures based on the Finite Element Method (FEM) are diverse. In general, they can be divided into three groups based on their length scale: macro‐, meso‐, and micro‐scale models. The macro‐scale models are the simplest approach and require the least computational cost. On the contrary, the micro‐scale models are the most realistic and complex, thus involving extremely high computational costs. The meso‐scale models stand in the middle with sufficient representation degree at a reasonable computational cost. Every group of models has its own advantageous application field. For the forming process of 3D preforms, macro‐scale models have been widely used. As computational costs drop over time, meso‐scale models become more and more favorable. Hence, research efforts increasingly focus on meso‐scale models. In this paper, the modeling methods of FEM meso‐scale models for plain woven fabric made of glass roving and biaxial reinforced weft‐knitted fabric made of carbon fiber/polyamide 6.6 hybrid yarns are introduced. The experimental tests are used to characterize the mechanical properties of the yarns and fabrics. Different modeling methods for the geometries of each type of fabric are described. The mechanical behavior of the models is calibrated and validated with the help of a series of test simulations. Examples for the usage of the introduced models are presented.

This study investigates the influence of thermoplastic non-woven veils on the interlaminar fracture energy and toughening mechanisms under mode-I dominant loading conditions in out-of-autoclave resin-infused carbon fibre-epoxy laminates. Two different non-woven micro-fibre veils, Polyetherimide (PEI) and Polyphenylene Sulfide (PPS), of low areal weight (∼10 g/m2) are introduced between carbon fibre non-crimp fabric (NCF) laminae prior to vacuum assisted resin infusion (with a low viscous two-part epoxy resin, i.e. Araldite 564/Aradur 2954). Double Cantilever Beam (DCB) specimens are tested for characterising mode-I fracture energies, and a novel miniature specimen geometry with an embedded fibre-discontinuity to trigger delamination under mode-I dominant loading is employed for in-situ SEM characterisation of micro-damage evolution and toughening mechanisms. The results obtained from DCB specimens showed that the micro-fibre thermoplastic veils considerably improved the mode-I fracture energy when compared with the untoughened fracture energy (i.e. ∼13% increase with PEI and ∼60% with the PPS veils, at the onset of crack propagation). Optical and scanning electron microscopy revealed that the veil parameters such as fibre dispersion, fibre diameter and specific surface area play an important role in enhancing fracture energy. Fracture surface micrographs indicated that progressive fibre-matrix debonding followed by fibre pull-out and fibre bridging resulted in higher fracture energy within the PPS veils. Interleaving a relatively low-cost NCF composite with thermoplastic veils could be as resistant to delamination as aerospace-grade carbon fibre-epoxy systems.

[Display omitted] Recent research highlights the influence of chopped carbon fiber (CF) bundle dimensions on Sheet Molding Compound (SMC) properties. This study employs a meso -scale finite element method (FEM), integrating a compaction modeling approach to capture non-uniform morphology. A central line method tracks bundle movement during compression, compiling orientation statistics. Employing a full test coupon-sized meso -scale model for analysis, results consistently align with experiments, indicating enhanced tensile and flexural performance in SMC with thinner or narrower CF bundles, attributed to a more uniform filler distribution and increased bundle interactions. However, no definitive relationship is observed between out-of-plane orientation and these properties. Despite omitting interface effects and resin flow during compression, the numerical analyses offer insights into SMC's structure-properties relationship, advancing high-performance material development. [ABSTRACT FROM AUTHOR]

Environmental factors in saxicolous lichen communities are scale dependent, yet the influence of scale is not often specifically addressed in ecological studies. This study examined three scales [micro (cm), meso (meters–10s of meters), macro (km)] in granite rock communities and compared species assemblages and disturbance regimes in Lake Superior shoreline and inland habitats. Percent cover of lichens and environmental variables were measured in 1280 20 × 20-cm plots across 16 sites (8 lakeshore and 8 inland). A perMANOVA analysis showed that the composition of lakeshore and inland lichen communities was significantly different (F=17.2, df=1,4, P <0.001). Adjacent lakeshore sites were more similar (F=8.550; df = 1, 26; p=0.007) to each other than they were to sites further away, while inland sites were not (F=0.545; df=1, 26; p=0.467). Variation in disturbance is likely more important in determining inter-site variation in inland areas. Mesoscale environmental variables such as solar radiation, height above Lake Superior, and an aspect/slope index were better predictors of species assemblages than microscale variables. However, individual species differed greatly in their associations with specific habitat variables. A host of microhabitats were discovered, with some lichens specializing on rock overhangs, quartz veins, cracks, subtle variations in rock texture, and mafic intrusions within granite. [ABSTRACT FROM AUTHOR]

[Display omitted] The notion of the contact line is fundamental to capillary science, where in a large category of wetting phenomena, it was always regarded as a one-dimensional object involving only microscopic length scales. This prevailing opinion had a strong impact and repercussions on the developing theories and methodologies used to interpret experimental data. It is hypothesised that this is not the case under certain conditions leading to non-local effects and requiring the development of a modified force balance at the contact line. Using the first principles of molecular dynamic simulations and a unique combination of steady state conditions and observables, the microscopic structure of the contact region and its connections with macroscopic quantities of capillary flows was revealed for the first time. The contact line is shown to become a non-local, macroscopic object involving rather complex interplay between microscopic distributions of density, velocity and friction force. It was established that the non-locality effects, which cannot be in principle captured by localised methodologies, kick off at a universal tipping point and lead to a modified force balance. The developed framework is applicable to a wide range of capillary flows to identify and analyse this regime in applications. [ABSTRACT FROM AUTHOR]

In‐situ sensors for riverine water quality monitoring are a powerful tool to describe temporal variations when efficient and informative analyses are applied to the large quantities of data collected. Concentration‐discharge hysteresis patterns observed during storm events give insights into headwater catchment processes. However, the applicability of this approach to larger catchments is less well known. Here, we evaluate the potential for high‐frequency turbidity‐discharge (Q) hysteresis patterns to give insights into processes operating in a meso‐scale (722 km2) northern mixed land use catchment. As existing event identification methods did not work, we developed a new, objective method based on hydrograph characteristics and identified 76 events for further analysis. Qualitative event analysis identified three recurring patterns. Events with low mean Q (≤ 2 m3/s) often showed short‐term, quasi‐periodic turbidity variation, to a large extent disconnected from Q variation. High max Q events (≥15 m3/s) were often associated with spring flood or snowmelt, and showed a disconnection between turbidity and Q. Intermediate Q events (mean Q: 2–11 m3/s) were the most informative when applying hysteresis indexes, since changes in turbidity and Q were actually connected. Hysteresis indexes could be calculated on a subset of 60 events, which showed heterogeneous responses: 38% had a clockwise response, 12% anticlockwise, 12% figure eight (clockwise–anticlockwise), 10% reverse figure eight (anticlockwise–clockwise) and 28% showed a complex response. Clockwise hysteresis responses were associated with the wetter winter and spring seasons. Generally, changes in Q and turbidity were small during anticlockwise hysteresis events. Precipitation often influenced figure‐eight patterns, while complex patterns often occurred during summer low flows. Analysis of intermediate Q events can improve process understanding of meso‐scale catchments and possibly aid in choosing appropriate management actions for targeting a specific observed pattern. [ABSTRACT FROM AUTHOR]

Chloride ion corrosion of steel bars is one of the important reasons for the decline of durability and service life of concrete structures. Due to the complexity of concrete structure, the migration process of chloride ions in concrete is diversified. Therefore, it is difficult to show the transport mechanism of chloride ions in concrete by a single experimental study. It is necessary to explore the transmission process and mechanism of chloride ions in concrete through theoretical simulation on the basis of experimental research. This paper summarizes the relevant models and methods of chloride transport, points out the advantages and disadvantages of existing models, and prospects the research direction of chloride transport models.

Recent studies provide novel insights into the meso‐scale organization of the brain, highlighting the co‐occurrence of different structures: classic assortative (modular), disassortative, and core‐periphery. However, the spectral properties of the brain meso‐scale remain mostly unexplored. To fill this knowledge gap, we investigated how the meso‐scale structure is organized across the frequency domain. We analyzed the resting state activity of healthy participants with source‐localized high‐density electroencephalography signals. Then, we inferred the community structure using weighted stochastic block‐model (WSBM) to capture the landscape of meso‐scale structures across the frequency domain. We found that different meso‐scale modalities co‐exist and are diversely organized over the frequency spectrum. Specifically, we found a core‐periphery structure dominance, but we also highlighted a selective increase of disassortativity in the low frequency bands (<8 Hz), and of assortativity in the high frequency band (30–50 Hz). We further described other features of the meso‐scale organization by identifying those brain regions which, at the same time, (a) exhibited the highest degree of assortativity, disassortativity, and core‐peripheriness (i.e., participation) and (b) were consistently assigned to the same community, irrespective from the granularity imposed by WSBM (i.e., granularity‐invariance). In conclusion, we observed that the brain spontaneous activity shows frequency‐specific meso‐scale organization, which may support spatially distributed and local information processing. [ABSTRACT FROM AUTHOR]

This study demonstrates a homogenization approach via a modified state-based peridynamic (PD) method to predict the effective elastic properties of composite materials with periodic microstructure. The procedure of modeling the PD unit cell (UC) of continuous fiber-reinforced composite is presented. Periodic boundary conditions are derived and implemented through the Lagrange multiplier method. A matrix-dominated approach for modeling the interphase properties between dissimilar materials is proposed. The periodicity and continuity assumptions are employed to determine the stress and strain fields, as well as the effective elastic properties. The PD-UCs of square and hexagonal packs as well as the 0/90 laminate microstructure are modeled and compared with the analytical, numerical and experimental results from the literature. Good agreement of predicted effective properties can be observed. Unlike other PD homogenization approaches, the effective material properties can be directly and individually obtained from simple loading conditions. [ABSTRACT FROM AUTHOR]

Considering that the machining of composites particularly fiber-reinforced polymer composites (FRPCs) has remained a challenge associated with their heterogeneity and anisotropic nature, damage caused by drilling operations can be considerably mitigated by following optimum cutting parameters. In this work, we numerically evaluated the effects of cutting parameters, such as feed rate and spindle speed, on the thrust force and torque during the drilling of glass-fiber-reinforced polymers (GFRPs). A meso-scale, also known as unidirectional ply-level-based finite element modeling, was employed assuming an individual homogenized lamina with transversely isotropic material principal directions. To initiate the meso-scale damage in each lamina, 3D formulations of Hashin’s failure theory were used for fiber damage and Puck’s failure theory was implemented for matrix damage onset via user subroutine VUMAT in ABAQUS. The developed model accounted for the complex kinematics taking place at the drill–workpiece interface and accurately predicted the thrust force and torque profiles as compared with the experimental results. The thrust forces for various drilling parameters were predicted with a maximum of 10% error as compared with the experimental results. It was found that a combination of lower feed rates and higher spindle speeds reduced the thrust force, which in turn minimized the drilling-induced damage, thus providing useful guidelines for drilling operations with higher-quality products. Finally, the effect of coefficient of friction was also investigated. Accordingly, a higher coefficient of friction between the workpiece and drill-bit reduced the thrust force.

Collapse of granular material is usually accompanied by long run-out granular flows in natural hazards, e.g. rock/debris flow and snow avalanches. This paper presents a novel multi-scale approach for modelling granular column collapse with large deformation. This approach employs the smoothed particle hydrodynamics (SPH) method to solve large deformation boundary value problems, while using a micromechanical model to derive the nonlinear material response required by the SPH method. After examining the effect of initial cell size, the proposed approach is subsequently applied to simulate the flow of granular column in a rectangular channel at a low water content by varying the initial aspect ratio. The numerical results show good agreement with various experimental observations on both collapse process and final deposit morphology. Furthermore, the meso-scale behaviour is also captured owing to the advantages of the micromechanical model. Finally, it was demonstrated that the novel multi-scale approach is helpful in improving the understanding of granular collapse and should be an effective computational tool for the analysis of real-scale granular flow. [ABSTRACT FROM AUTHOR]

In this article, dissipative particle dynamics with energy conservation eDPD is used for simulating hydrodynamic behavior and heat transfer of DPD particles in a two-dimensional channel with parallel planes. To this end, a Fortran programming code is developed and the results are presented as dimensionless velocity and temperature profiles on the cross section perpendicular to the flow direction inside the channel. For the indented geometry, thermal and dynamic boundary conditions have been considered. The dynamic boundary condition of solution domain in the flow's direction is periodic, and for modeling the walls, freezing layers of DPD particles with Bounce-Back reflection has been used. For the thermal boundary condition, it is assumed that the wall temperature is constant and the temperature of each DPD particle in contact with the wall is the same as the wall temperature. In this article, for the first time, for modeling the walls four frozen layers with Bounce-Back reflection are used and the effect of particle exit on two and three-layers configurations is investigated. Furthermore, for the first time, modified velocity Verlet integration algorithm is improved by adding heat transfer equations. And considering λ = 0.65 in the algorithm; the indented geometry is well simulated. In order to validate the results, first, the effect of regular and random initial distribution is compared. Furthermore, the results of wall alignment are compared with those obtained from CFD approach. In this paper, in addition to studying the effect of wall alignment and initial particle arrangement, the influence of the size of cells for averaging and the time steps in the output results are investigated. [ABSTRACT FROM AUTHOR]

Granular materials have a complex collective behavior based on simple interactions between grains. The global behavior stems from dynamic rearrangements in the micro-structure. The local increase (resp. decrease) of the density generates jamming (resp. unjamming). In this paper, instabilities in the form of localized bursts of kinetic energy are studied at both the micro-scale (i.e. grain scale) and meso-scale (i.e. cluster scale). The bursts are defined from the variation of kinetic energy. The meso-domains (grain loops in 2D) are built from the tessellation of the medium. We analyze the gain and loss of meso-structures during a localized burst. Surprisingly, micro-structural reorganizations are able to keep the overall statistical equilibrium constant. The introduction of strain-like and stress-like quantities at the mesoscopic scale makes it possible to propose an expression that can be assimilated to mesoscopic second-order work. At this intermediate scale, the negative values of the second-order work are correlated to the appearance of bursts of kinetic energy, which stands for a meso-scale counterpart of Hill's macroscopic criterion of mechanical instability. [ABSTRACT FROM AUTHOR]

Oxygen-enriched combustion is expected to be introduced into small scale to improve the characteristics of micro- or meso-scale combustion. To fully understand the advantages of oxygen-enriched combustion, the ignition characteristics of n-butane/oxygen-enriched air mixtures are studied by the experimental and numerical methods in a heated quartz tube with an inner diameter of 5 mm. The experimental results show that the oxygen enrichment level, equivalence ratio, and flow rate have an important influence on the ignition temperature of the mixed gas in the tube. The ignition temperature decreases with the increasing oxygen enrichment and is strongly affected by oxygen concentration at higher equivalence ratio and lower oxygen enrichment level. In the meanwhile, higher equivalence ratio and lower flow velocity also significantly reduce the ignition temperature in the experimental cases. Furthermore, the increase in the oxygen enrichment level significantly enhances the effect of the equivalence ratio on the ignition temperature while higher flow velocity slightly weakens the effect. The numerical results show that oxygen enrichment is beneficial to the production of OH radicals in pre-ignition period and significantly promotes the oxydehydrogenation reactions of intermediates. [ABSTRACT FROM AUTHOR]

In order to overcome the shortcomings of traditional pure macro- and meso-scale crack growth simulation method, here an adaptive multi-scale beam lattice method (AMBLM) is developed to simulate trans-scale crack growth process from meso-scale to macro-scale for quasi-brittle heterogeneous concrete-like materials with low computation cost. In the trans-scale crack growth simulation, dangerous regions can be automatically found and the meso-scale model is then re-modeled in the found region, which can ensure continuous changes in the adaptive multi-scale modeling due to cracking. In this way, the meso-scale simulation is only implemented in the dangerous region of crack growth paths, and macro-scale simulation is implemented in other regions. This can improve computational efficiency of the developed method significantly. In order to verify the developed AMBLM, the trans-scale crack growth process of two concrete specimens are simulated. Then the simulation results are compared with experimental results, which show that the developed AMBLM is effective. In addition, the simulation results are also compared with the computation results obtained from pure meso-scale simulation. The results show that AMBLM has very high precision and superior computational efficiency on multi-scale crack growth simulation of quasi-brittle concrete-like materials. [ABSTRACT FROM AUTHOR]

Small-scale power generation using heat energy from hydrocarbon fuels is a proven technology. In this study, we analyzed 2-D flame development in mesoscale Swiss roll combustor. A mixture of 60% butane and 40% propane was used (0.25–0.55 L per minute). During all the analyses, equivalence ratio (1.1) was kept constant by adjusting air quantity against fuel quantity. The effect of increase in the mixture velocity on the development of flame shapes/patterns was monitored. We found different patterns of flame, e. g., planar, concave, and conical, with the increase in mixture velocity. Increase in combustion chamber temperature was also noted. No flashback was observed and blowout was observed with very high mixture velocity. Combustion chamber temperatures were found to be increasing with the increase in mixture velocity at the same equivalence ratio. Elongation of the flame was observed because of the increased flow velocity. Heat re-circulation to the reactants enhances flame characteristics. [ABSTRACT FROM AUTHOR]