Cross-scale Analysis Research Articles

Cross-scale study on the influence of moisture-temperature coupling conditions on adhesive properties of rubberized asphalt and steel slag

In order to study the effects of moisture and temperature on the interfacial adhesion characteristics between rubberized asphalt and steel slag, the interfacial adhesion properties between rubberized asphalt and steel slag under different immersion temperatures were studied. At the molecular scale, the interaction between rubberized asphalt model and steel slag representative minerals (Ca3SiO5 and Ca2SiO4) models were studied by molecular dynamics simulation. The bonding properties between rubberized asphalt and steel slag were analyzed and studied by direct tensile bonding failure test at macro scale. Through the correlation analysis between the macro scale direct tensile bonding failure test results and the molecular scale interface interaction, the cross-scale performance of moisture temperature on the adhesion characteristics between rubberized asphalt and steel slag was revealed. The results show that the type of interaction between steel slag molecules and asphalt molecules is consistent with that of natural minerals, and they all interact by hydrogen bond. Water molecules on the surface of steel slag molecular distribution is in a stepped pattern, asphalt molecules on the surface of steel slag molecular distribution are more uniform. Under the influence of rising temperature, water molecules further gather to the surface of steel slag molecules, and asphalt molecules gather away from steel slag molecules. When the temperature rises from 40 °C to 50 °C, the interaction energy density between rubberized asphalt and steel slag molecules hardly changes, and the interaction energy density decreases significantly when the temperature rises to 60 °C. Under the action of tensile stress, Ca2SiO4 shows weaker interaction with rubberized asphalt, while the interface of Ca3SiO5 and rubberized asphalt is less affected by external force. At the same time, 60°C is more obvious as the threshold temperature of interface strength decline under the action of external force. There is a good power function correlation between the macro bonding failure energy density and the molecular interaction energy density. The regularity within each scale is consistent, which confirms the rationality of cross-scale analysis of the same observation object between different scales. However, there are still great differences in the absolute values of indexes between different scales, which indicates that the simple numerical correspondence cannot be carried out in the cross-scale analysis due to the different ideal degree of models.

Cross-scale analysis of temperature compensation in the cyanobacterial circadian clock system

Circadian clock proteins often reveal temperature-compensatory responses that counteract temperature influences to keep their enzymatic activities constant over a physiological range of temperature. This temperature-compensating ability at the reaction level is likely crucial for circadian clock systems, to which the clock proteins are incorporated, to achieve the system-level temperature compensation of the oscillation frequency. Nevertheless, temperature compensation is yet a puzzling phenomenon, since side chains that make up the clock proteins fluctuate more frequently due to greater thermal energy at higher temperature. Here, we investigated temperature influences on the dynamics of KaiC, a temperature-compensated enzyme (ATPase) that hydrolyzes ATP into ADP in the cyanobacterial circadian clock system, using quasielastic neutron scattering. The frequency of picosecond to sub-nanosecond incoherent local motions in KaiC was accelerated by a factor of only 1.2 by increasing the temperature by 10 °C. This temperature insensitivity of the local motions was not necessarily unique to KaiC, but confirmed also for a series of temperature-sensitive mutants of KaiC and proteins other than clock-related proteins. Rather, the dynamics associated with the temperature-compensatory nature of the reaction- and system-level was found in global diffusional motions, which was suggested to regulate the temperature dependence of ATPase activity and dephosphorylation process presumably through changes in the hexamer conformation of KaiC. The spatiotemporal scale at which cross-scale causality of the temperature sensitivity is established is finite, and extends down to picosecond to sub-nanosecond dynamics only in a very limited part of KaiC, not in its entire part.

Intrinsic heterogeneity of grain boundary states in ultrafine-grained Ni: A cross-scale study by SIMS and radiotracer analyses

Using a correlated diffusion study applying secondary-ion mass spectroscopy (SIMS) and radiotracer analyses, the co-existence of both relaxed and deformation-modified non-relaxed high-angle grain boundaries (GBs) in ultrafine-grained Ni of 2N6 purity processed by equal channel angular pressing (ECAP) is clearly revealed. Due to different depth and lateral resolutions and using experimentally accessible diffusion times, SIMS provides a direct access to the properties of relaxed “slow” GBs (at short penetration depths) while the radiotracer measurements reveal simultaneously the contribution of the deformation-modified “fast” GBs (at large penetration depths). The temperature stability of ultrafine-grained structure of 2N6 Ni is investigated using electron back-scatter diffraction after annealing treatments corresponding to the diffusion experiments. No changes of the ECAP-produced microstructure occur at 403 K, while the ultrafine-grained structure is remarkably evolving to a coarse-grained one at 603 K. The knowledge of the microstructure evolution is used to quantify the diffusion data. The combination of the two complementary techniques allows not only to perform a cross-scale analysis of the mass transport, but also to probe consistently the existence and kinetic properties of different multi-level hierarchic microstructure features. Therefore, the results obtained is a step forward a better understanding of the physics of ultra-fine-grained materials (UFG). For the first time in the case of UFG materials, the SIMS technique is used in a mode with lateral resolution which is correlated with the microstructure characteristics resolving a multi-level hierarchy of diffusion properties of short circuits in severe plastically deformed materials.

A Novel Calculation Method of Hydrodynamic Pressure Based on Polyhedron SBFEM and Its Application in Nonlinear Cross-Scale CFRD-Reservoir Systems

Hydrodynamic pressure is an important factor that cannot be ignored in the seismic safety evaluation of dams. However, when the polyhedron-scaled boundary finite element method is used to simulate dams in a cross-scale dynamic analysis, polygonal surfaces often appear on the upstream face of dams, which is difficult to deal with for conventional methods of hydrodynamic pressure. In this paper, a three-dimensional calculation method of hydrodynamic pressure based on the polyhedron-scaled boundary finite element method is proposed, in which polygon (triangle, quadrilateral, pentagon, hexagon, heptagon, octagon, etc.) semi-infinite prismatic fluid elements are constructed using the mean-value shape function. The proposed method, with a high efficiency, overcomes the limitation of conventional methods in which only quadrangle or triangle boundary faces of elements are permitted. The accuracy of the proposed method is proved to be high when considering various factors. Furthermore, combined with the polyhedron-scaled boundary finite element method for a solid dam, the proposed method for reservoir water is used to develop a nonlinear dynamic coupling method for cross-scale concrete-faced rockfill dam-reservoir systems based on the polyhedron SBFEM. The results of the numerical analysis show that when the hydrodynamic pressure is not considered, the error of rockfill dynamic acceleration and displacement could reach 15.4% and 12.7%, respectively, and the error of dynamic face slabs’ stresses could be 24.9%, which is not conducive to a reasonable seismic safety evaluation of dams.

Blurring the boundaries: cross-scale analyses of food systems

The globalized and interconnected nature of food systems provides many examples of panarchies within social-ecological systems. However, few are analyzed using panarchy theory, particularly urban food systems, or in a comparative manner. We aimed to broaden the examination of cross-scale dynamics of food systems by applying panarchy theory through comparative study of three urban food systems: Flint, Michigan, Cleveland, Ohio, and Pittsburgh, Pennsylvania. These are all post-industrial Rust Belt cities that have experienced similar economic downturns but have responded in different ways, which has created significantly different food system outcomes. We present an approach for applying panarchy theory in food systems, and identifying indicators of potential and connectedness at multiple scales with sources for such data. We analyzed available data and demonstrate how the economic history of these cities has influenced their food system outcomes today. Economic recovery at the city scale in Pittsburgh/Allegheny County was reflected in reorganization in the food system, while the lack of economic recovery in Flint/Genesee County and the uneven access to economic recovery in Cleveland/Cuyahoga County potentially placed the cities and their food systems in lock-in traps. We also reflect on the limitations of publicly available data at the city scale for the food system and over time. Overlooking such gaps may blur boundaries within a panarchy analysis and lead to assumptions about cities based on county data which might not be accurate or may hide critical variables such as race or geographic size. We caution researchers to be clear about scale in panarchy analyses and to acknowledge the limitations of current data sets and thus the importance of mixed methods primary data collection. The incorporation of place and historical context into panarchy analyses can lend valuable explanatory power to our understanding of cross-scale dynamics in food systems.

Barriers Everyone: A New Method for Multiscale Analysis of Barriers Using the Barrier Index

Abstract The Barrier Index is presented in this contribution. The index shows the extent to which spatial units of different sizes are closed off by barriers, influencing society by the different “thickness” and “thinness” of boundaries. The article defines the Index and compares land units with barriers in various details. The calculations were made for spatial units from the scale of parcels to one-hectare areas in selected types of regions, selected geographic regions, and border barriers in selected countries. The Index is useful for crossscale analysis and for identifying the underlying causes and relationships within different cultural, social, and geographical contexts. The example of spatially persistent family structures was used to highlight the underpinning influencing factors that connect the building of barriers at different scales.

Cross-scale trade-off analysis for sustainable development: linking future demand for animal source foods and ecosystem services provision to the SDGs

Dietary transition towards higher consumption of animal source foods (ASF) associated with higher incomes across low and middle-income countries could have negative impacts on environmental systems and their potential in the long run to provide services necessary for achieving multiple Sustainable Development Goals (SDGs). In this article, we integrate economic, land use allocation, and biophysical models to investigate trade-offs between the five ecosystem services and their contributions to various SDGs associated with agricultural expansion to meet future demand for ASF, using Tanzania as a case study. Our results show that under the scenario of sustainable socio-economic development, between 2010 and 2030 in Tanzania, per capita income grows by 169% and the share of population at risk of hunger declines from 34.8% to 23%. These changes can be associated on a macro-level with positive contributions to achievement of SDG 1 (No Poverty) and SDG 2 (Zero Hunger). To satisfy feed demand for increased livestock production domestically, an increase by 21.4% of biomass production as compared to 2010 is needed. Analysis of alternative scenarios for meeting this new demand shows potential threats on a landscape level to achieving numerous SDGs and more generally to attaining sustainable food systems. Ecosystem-based contributions primarily decline to SDGs: SDG 3 (Health), SDG 6 (Clean Water), SDG 11 (Sustainable Cities), SDG 13 (Climate) and SDG 15 (Terrestrial Life). We find that higher crop productivity and redesign of agro-ecosystems to increase on-farm tree cover could significantly limit these losses. Alternatively, the growing demand for ASF could be satisfied with imports, which would allow for reducing the trade-offs locally. However, this would result in at least partially only displacing ecosystem service losses to the exporting countries.

An interdisciplinary view of the long-term evolution of repository systems across scales: the iCROSS project

Abstract. The interdisciplinary project “Integrity of nuclear waste repository systems – Cross-scale system understanding and analysis (iCROSS)” combines research competencies of Helmholtz scientists related to the topics of nuclear, geosciences, biosciences and environmental simulations in collaborations overarching the research fields energy and earth and environment. The focus is to understand and analyze close-to-real long-term evolutionary pathways of radioactive waste repositories across nanoscales to repository scales. The project is subdivided into work packages dealing with laboratory studies, field experiments in underground research laboratories (URLs), advanced modelling studies and the integration and alignment of data and information using virtual reality methods. In this sense, the project structure aims at a holistic view on relevant processes across scales in order to comprehensively simulate potential repository evolutions. Within the multi-barrier system of a repository for heat-generating radioactive waste, a number of complex reactions proceed, including dissolution, redox processes, biochemical reactions, gas evolution and solid/liquid interface and (co)precipitation reactions. At the same time, thermal and external mechanical stress has an impact on the conditions in a deep geological repository. All those processes are highly coupled, with multiple interdependencies on various scales and have a strong impact on radionuclide mobility and retention. In recent years, substantial progress was achieved in describing coupled thermal-hydro-mechanical-chemical-biological (THM/CB) processes in numerical simulations. A realistic and concise description of these coupled processes on different time and spatial scales is, at present, a largely unresolved scientific and computational challenge. The close interaction of experimental and simulation teams aims at a more accurate quantification and assessment of processes and thus, the reduction of uncertainties and of conservative assumptions and eventually to a close-to-real perception of the repository evolution. One focus of iCROSS is directed to relevant processes in a clay rock repository. In this context, the iCROSS team became a full member of the international Mont Terri consortium and worked in close collaboration with international and German institutions in URL projects. Respective experiments specifically deal with coupled processes at the reactive interfaces in a repository near field (e.g. the steel/bentonite and bentonite/concrete interfaces). Within iCROSS, the impact of secondary phase formation on radionuclide transport is investigated. At Mont Terri, experiments are in preparation to study radionuclide transport phenomena in clay rock formations within temperature gradients and in facies exhibiting significant heterogeneities on different scales (nm to cm). Beside those studies, high resolution exploration methods for rock characterization are developed and tested and the effect of temperature and other boundary conditions on the strength, creep properties and healing of faults within Opalinus clay are quantified. Multiphysics models coupled to reactive transport simulation have been further developed and applied to laboratory and field experiments. Results are digitally analyzed and illustrated in a visualization center, in order to enhance the comprehension of coupled processes in repository systems across scales. The present contribution provides an overview on the project and reports selected results. The impact of considering complex coupled processes in repository subsystems for the assessment of the integrity of a given (generic) repository arrangement is discussed.

Impact of the heterogeneity of the sandy Opalinus clay facies at the Mont Terri underground research laboratory on radionuclide migration

Abstract. The assessment of the safety of a deep geological repository (DGR) for high-level radioactive wastes over assessment time scales of up to 1 million years requires an in-depth understanding of the multi-scale coupled processes that affect the repository system evolution over time, to reduce uncertainties and conservatism in safety analyses. This is in particular required with respect to the challenges of a comparative assessment of different repository concepts in different host rocks within the process of a site selection for a DGR for heat-generating radioactive wastes in Germany. The collaborative project “Integrity of nuclear waste repository systems – Cross-scale system understanding and analysis (iCross)” conducted jointly by five research centres of the Helmholtz Association and co-funded by the Initiative and Networking Fund of the Helmholtz Association and the Federal Ministry of Education and Research (BMBF) has been initiated with the overall objective to improve the understanding of coupled thermal-hydraulic-mechanical-chemical-(micro)biological (THMCB) processes and to develop simulation tools that enable a holistic close to reality description of the long-term evolution of the repository system. Geological formations, such as those foreseen as potential host rocks for DGRs, and their surroundings are heterogeneous on various length scales ranging from nanometers to kilometers. Therefore, the aim of this work in the context of iCross is to evaluate the effects of mineralogical, geochemical and microstructural heterogeneities of repository host rocks on radionuclide transport in the repository far field, using the sandy facies of the Opalinus clay (SF-OPA) from the Mont Terri underground research laboratory (St. Ursanne, Switzerland) as an example. Here, we address in particular the migration behaviour of Ra-226 as an important radionuclide to be considered in safety cases for deep geological disposal of spent nuclear fuel. To assess the impact of the heterogeneities in SF-OPA on radionuclide transport, a complementary approach combining microstructural characterisation methods, experimental techniques for the determination of transport parameters of the rock matrix and the mobility of Ra-226 with innovative developments in reactive transport modelling on the pore and continuum scales was pursued. One of the results was that although the limited clay content in SF-OPA decreases the total amount of Ra bound to the illite phase, the solid solutions of sulphate and carbonate compensate for this and provide a major fixation mechanism.

Cross-scale analysis of diversification processes in fuelwood use in three contrasting ecoregions of Argentina (Chaco, Pampa and Patagonia): the role of exotic species in subsistence

Fuelwood is one of the main sources of energy for rural populations in many environments and ecosystems. However, little research has been done on the diversification processes associated with the use of woody plants for fuel (UWPF). This study was carried out in rural communities of three eco-regions of Argentina (the phytogeographical provinces of Chaco, Pampa and Patagonia). Open and semi-structured interviews were performed in 72 households, focusing on the current richness of fuelwood, supply strategies and gathering sites. The biogeographical origin of the mentioned species was established, and the pressure of use on fuel wood was evaluated indirectly. The results were analysed qualitatively and quantitatively. A total of 78 species was recorded, of which 51 were native and 27 exotic. Gathering is the most common supply strategy in all the ecoregions studied, fuelwood being obtained mainly in sites with little human intervention. Pressure of use did not vary between native and exotic species. A generalized linear model showed that the use of native versus exotic species varied according to the ecoregion and the level of human intervention in the supply area, while acquisition strategies were similar for both native and exotic species in all eco-regions. Each region presented different use patterns, but the areas with most human intervention were always used to gather exotic plants. In line with our hypothesis, the diversification processes in UWPF varied according to ecoregion, each area having intrinsic characteristics associated with its history. The exotic species currently used as fuel wood increase the repertory of plants recognised and used by the local population.

Philosophical Skepticism Concerning the Neutral Theory or Randomness: Misplaced or Misconceived? A Reply to Madison, "Stochasticity and Randomness in Community Assembly: Real or As-If?"

I appreciate a recent communication from Dr. Joseph Madison (1), titled “Stochasticity and randomness in community assembly: real or as-if?,” regarding my recent article (2), titled “Cross-scale analyses of animal and human gut microbiome assemblies from metacommunity to global landscape,” both published in mSystems.

Three-dimensional refined analysis of seismic cracking and anti-seismic measures performance of concrete face slab in CFRDs

The concrete face slab is the primary anti-seepage component of concrete faced rockfill dams (CFRDs). Therefore, the seismic safety of the slab is an important issue. In this paper, the cohesive zone model and the explicit solution are expanded to conduct 3D seismic failure analysis of a CFRD. A combination of the generalized plasticity model of rockfill, state-dependent elasto-plastic model of soil-structure interfaces, a non-uniform wave input method and the scaled boundary finite element method is used to perform an elasto-plastic, cross-scale analysis of the seismic cracking evolution of concrete face slabs. The above combined method is used to investigate the cracking mechanism, cracking characteristics and potential anti-seismic measures. The results indicate that the cyclic deformation caused by the earthquake results in the formation of horizontal, connected cracks in the middle of the slab at 70–75% of the dam height. In addition, the plastic deformation of the rockfill leads to the formation of horizontal, unconnected cracks on both sides of the slab at 85% of the dam height. A comprehensive anti-seismic measure is proposed based on material property improvement and structural optimization, decreasing the maximum crack width and the total crack length by 21% and 89.9%, respectively.

Cross-Scale Analyses of Animal and Human Gut Microbiome Assemblies from Metacommunity to Global Landscape

ABSTRACTAnimal (human) gut microbiomes have been coevolving with their hosts for many millions of years. Understanding how the coevolution shapes the processes of microbiome assembly and diversity maintenance is important but rather challenging. An effort may start with the understanding of how and why animals and humans may differ in their microbiome neutrality (stochasticity) levels. Here, we attempted to perform layered comparative stochasticity analyses across animal species (including humans), class, and kingdom scales, corresponding to microbial metacommunity, landscape, and global-landscape scales. By analyzing 4,903 microbiome samples from 274 animal species covering 4 major invertebrate classes and all 6 vertebrate classes and including 1,787 human gut microbiome samples, we discovered the following: (i) at the microbial metacommunity (animal species) scale, although the general trend of stochasticity (measured in the relationships between fundamental biodiversity/dispersal numbers of Hubbell’s neutral theory and host species phylogenetic timeline) seems continuous, there seems to be a turning point from animals to humans in the passing rate of neutrality tests (12% to 45% versus 100%). We postulate that it should be the human experiences from agricultural/industrial activities (e.g., diet effects) and frequent social/familial contacts that are responsible for the dramatically rising stochastic neutrality in human gut microbiomes. (ii) At the microbial landscape (animal class) and global landscape (animal kingdom) scales, neutrality is not detectable, suggesting that the landscape is niche differentiated—animal species may possess “home niches” for their coadapted microbiomes. We further analyze the reliabilities of our findings by using variable P value thresholds (type I error) and performing power analysis (type II error) of neutrality tests.IMPORTANCE Understanding how the coevolution (evolutionary time scale) and/or the interactions (ecological time scale) between animal (human) gut microbiomes and their hosts shape the processes of the microbiome assembly and diversity maintenance is important but rather challenging. An effort may start with the understanding of how and why animals and humans may differ in their microbiome neutrality (stochasticity) levels. Here, we attempted to perform layered comparative stochasticity analyses across animal species (including humans), class, and kingdom scales, corresponding to microbial metacommunity, landscape, and global-landscape scales by analyzing 4,903 microbiome samples from 274 animal species covering 4 major invertebrate classes and all 6 vertebrate classes, and including 1,787 human gut microbiome samples. The analyses were implemented by fitting the multisite neutral model and further augmented by checking false-positive and false-negative errors, respectively. It appears that there is a turning (tipping) point in the neutrality level from animal to human microbiomes.

Analysis and optimization of the machining fixture system stiffness for near-net-shaped aero-engine blade

Low stiffness of the near-net-shaped blade machining fixture of aero-engine creates challenges for the CNC machining accuracy and efficiency of near-net-shaped blade. This study aims to optimize the fixture’s material and structure to improve the stiffness of the blade-fixture system. First, the main influencing factors of the near-net-shaped blade tenon root CNC machining process were analyzed, and the influences of the positioning and clamping component materials and structures on the stiffness of the machining fixture were analyzed based on finite element analysis (FEA). Second, the mechanical properties of the positioning and clamping components of different materials and structures were analyzed based on cross-scale analysis from microscopic and macroscopic perspectives. Finally, the positioning and clamping components of the machining fixture were designed based on material selection and structure optimization, and the optimized machining fixture with new material and structural was verified by CNC machining process. The results showed that the material and structure of the positioning and clamping components were the main influencing factors of the machining fixture stiffness. The positioning and clamping components of the PEEK-GF30 material of the new splicing structure could effectively improve the blade-fixture stiffness.

Beyond multi-disciplinary and cross-scale analyses of the cyanobacterial circadian clock system.

Beyond multi-disciplinary and cross-scale analyses of the cyanobacterial circadian clock system.

A Cross-Scale Analysis of the Correlation between Daytime Air Temperature and Heterogeneous Urban Spaces

The problem of the urban thermal environment is becoming increasingly noticeable in the process of modern urban development. The temperature patterns in central business districts can be more complicated due to the heterogeneous urban spaces and diverse building forms, which need more cross-scale research. This study investigated the correlation between air temperature and urban morphology in a heterogeneous urban district in northeastern China. The thermal environment of the studied district in the summertime was simulated by ENVI-met. A total of 12 morphological indicators were selected to describe the geometric features of the studied district. Curve estimation was employed to quantify the correlation between air temperature and morphological indicators. The results indicate different effects of the morphological indicators of the air temperature on different scales. On a mesoscale, the compactness (Com), building footprint ratio (BFR), enclosure degree (ED) and total height to total floor area ratio (HA) had a significant correlation with the air temperature. On a microscale, only the BFR and ED had relatively steady correlations with the air temperature. The correlation between air temperature and morphological indicators could be influenced by the heterogeneity of the urban morphology, including the diversity of the heights and footprints of buildings and the irregularity of building horizontal arrangement.

Pattern transitions of localized deformation in high-porosity sandstones: Insights from multiscale analysis

We employ a hierarchical multiscale modeling approach to investigate the transitions of localized deformation patterns in high-porosity sandstone subjected to sustained shear to understand their underlying physics. The multiscale approach is based on hierarchical coupling between finite element method (FEM) with discrete element method (DEM) to offer cross-scale predictions for granular rocks without assuming phenomenological constitutive relations. Our simulations show that when a high-porosity sandstone specimen is subjected to continuous deviatoric loading, compaction bands may occur and evolve, featuring a steady movement of the compaction front (i.e. the boundary between the compaction band and the rest uncompacted zone). The specimen reaches a homogeneous state of reduced porosity when the compaction fronts traverse the entire specimen. A re-hardening response is initiated in the specimen under further shear, which is followed by a shearing dominating stage with the emergence of shear bands. The material responses inside the ultimate shear bands approach a “steady state” of constant porosity and stress ratio. Cross-scale analyses reveal that debonding and pore collapse are dominant mechanisms for the compaction stage of the specimen, and debonding and particle rotation dictate the physics for the shear banding stage. The transitions from compaction to shear banding occurs due to the degradation of the cohesive contact network and significant reduction in porosity. There are limited number of interparticle bonds remaining at the “steady state” under sustained shear, with a preferential direction perpendicular to the loading direction, leading to a higher steady void ratio than the critical state void ratio of non-cohesive sand.

Seismic cracking evolution for anti-seepage face slabs in concrete faced rockfill dams based on cohesive zone model in explicit SBFEM-FEM frame

It is critically importance to accurately locate vulnerable areas and quantitatively assess the damage of the face slab in the seismic safety evaluation of concrete faced rockfill dams (CFRDs). In this paper, the cohesive zone model (CZM) is augmented with generalized plastic models of the rockfill and state-dependent elasto-plastic model of the interface to investigate the seismic cracking evolution in the slab of CFRDs. An explicit coupled scaled boundary finite element method-finite element method (Explicit SBFEM-FEM) is developed to enable cross-scale analysis. The method considers the strain softening of rockfill and concrete after being damaged, and avoids negative stiffness and convergence problems that can be found during implicit analysis. A fine, cross-scale model of the CFRD is established based on the quadrature technique. Subsequently, simulations of the construction and impoundment processes are performed to facilitate dynamic analysis. In the first step, different damping ratios for the slab are simulated to optimize accuracy and efficiency. Then, the seismic cracking evolution of the slab is investigated in detail with consideration to the ground motion intensity and steel reinforcement. The results indicate that the computational efficiency can be significantly improved by decreasing the damping ratio of the concrete face slab in the explicit seismic analysis. Penetrating cracks are observed on the slab and the crack reaches maximum width during the earthquake. A residual width is retained after the earthquake. The simulated failure mode of face slab conforms to the characteristics of concrete. The developed method can help precisely locate weak areas of face slab, quantitatively determine the damage severity, and evaluate the ultimate seismic performance of the slab in the CFRDs. In addition, the method can be further employed for concrete cracking analysis involving soil-concrete interaction.

Cross-scale analysis of the energy recovery process in pressure exchanger and pipeline system

Cross-scale analysis of the energy recovery process in pressure exchanger and pipeline system

Measuring ecosystem multifunctionality across scales

Multifunctionality refers to the capacity of an area to supply multiple ecosystem functions or services. While many conceptual and methodological advances have focused on defining and quantifying multifunctionality, the challenge of dealing with cross-scale dynamics of multifunctionality remains open. This study proposes a new way of measuring multifunctionality across spatial scales, illustrated with a European-wide dataset of 18 ecosystem services. Our assessment captures not only the diversity of ecosystem services supplied within each municipality (alpha-multifunctionality), but also the unique contribution of each municipality to the regional ecosystem service diversity (beta-multifunctionality). This cross-scale analysis helps better understanding the spatial distribution of ecosystem services, which is required to design management and policies at the right scale. Our analysis shows that alpha-multifunctionality follows a latitudinal gradient across Europe and strongly decreases towards the city centers of metropolitan areas. By relating alpha- and beta-multifunctionality to land use intensity, we show that low-intensity management systems support higher ecosystem multifunctionality across Europe. Municipalities of low alpha-multifunctionality often contribute significantly to regional multifunctionality, by providing ecosystem services of a specific value to the region. Our method to measure both alpha- and beta-multifunctionality thus provides a new way to inform reconciliation of competing land uses when maximizing alpha-multifunctionality is not reasonable.