Dynamic Continuum Research Articles

Dynamic tensile intralaminar fracture and continuum damage evolution of 2D woven composite laminates at high loading rate

The intralaminar tensile failure of 2D woven composites under dynamic tensile load was investigated in this paper. Compact tension samples were tested at high loading rate with an electromagnetic Hopkinson bar system. The strain field was obtained with high-speed imaging and digital image correlation, and the J-integral method was employed to obtain the fracture toughness and corresponding R-curve. The continuum damage evolution of intralaminar failure was then analyzed by tracking the opening near the initial crack tip. It is found that the dynamic intralaminar fracture toughness is decreased by 51% compared to the quasi-static condition, the continuum damage evolution and its dependence on loading rate have been reported as well. The failure mechanisms were studied with thermal imaging and scanned electron microscopy, shorter fibre pull-out length and thinner failure process zone may be responsible for the reduced toughness at high loading rate.

Single-cell analysis of breast cancer metastasis reveals epithelial-mesenchymal plasticity signatures associated with poor outcomes.

Metastasis is the leading cause of cancer-related deaths. It is unclear how intratumor heterogeneity (ITH) contributes to metastasis and how metastatic cells adapt to distant tissue environments. The study of these adaptations is challenged by the limited access to patient material and a lack of experimental models that appropriately recapitulate ITH. To investigate metastatic cell adaptations and the contribution of ITH to metastasis, we analyzed single-cell transcriptomes of matched primary tumors and metastases from patient-derived xenograft models of breast cancer. We found profound transcriptional differences between the primary tumor and metastatic cells. Primary tumors upregulated several metabolic genes, whereas motility pathway genes were upregulated in micrometastases, and stress response signaling was upregulated during progression. Additionally, we identified primary tumor gene signatures that were associated with increased metastatic potential and correlated with patient outcomes. Immune-regulatory control pathways were enriched in poorly metastatic primary tumors, whereas genes involved in epithelial-mesenchymal transition were upregulated in highly metastatic tumors. We found that ITH was dominated by epithelial-mesenchymal plasticity (EMP), which presented as a dynamic continuum with intermediate EMP cell states characterized by specific genes such as CRYAB and S100A2. Elevated expression of an intermediate EMP signature correlated with worse patient outcomes. Our findings identified inhibition of the intermediate EMP cell state as a potential therapeutic target to block metastasis.

Chaos-BBO: Chaos balanced butterfly optimizer with dynamic continuum chaotic strategies and its applications

Chaos-BBO: Chaos balanced butterfly optimizer with dynamic continuum chaotic strategies and its applications

Adaptive Scheduling of Continuous Operators for IoT Edge Analytics

In this paper, we address the problem of adaptive scheduling of data stream processing and analytics (DSPA) applications in a shared edge fog cloud (EFC) continuum with response time constraints. The focus is on handling the dynamic workload of DSPA applications caused by the variability of their input data stream rates generated by mobile IoT devices, and the dynamically available resource capacity in the EFC continuum. To address these challenges, we characterise the different types of resources in the EFC continuum, as well as the operators that make up a DSPA application. Based on this characterisation, we propose models to evaluate the response time and the cost of using the resources in the always dynamic EFC continuum. We then formulate the problem of adaptive scheduling of a DSPA application in the EFC continuum with the objective of minimising the cost of using the shared resources subject to the constraints of the response time and the available capacity of the EFC resources. We propose a heuristic algorithm that dynamically computes a new scheduling of the DSPA application, taking into account its current deployment state and the current state of the shared resources in the EFC continuum. Experimental results, using simulation, show the effectiveness of our proposed algorithm against algorithms of related work.

Towards improved online dissolution evaluation of Pt-alloy PEMFC electrocatalysts via electrochemical flow cell - ICP-MS setup upgrades

Electrochemical flow cell coupled with an inductively coupled plasma mass spectrometer (EFC-ICP-MS) is a powerful electroanalytical technique to monitor in-situ dissolution of metallic electrocatalysts and to understand mechanism of degradation under operating conditions. Its utilisation has witnessed a notable increase in the electrocatalyst field in the last decade where it has been extensively used to study the stability of platinum group metals (PGMs) under oxygen reduction and oxygen evolution reaction conditions. Online ICP-MS has allowed the scientific and industrial community to optimise the activity and stability of PGMs thanks to a better understanding of the complex metal corrosion processes. Among the different setups, the electrochemical flow cell design is the most common as it is based on a commercially available design. Nonetheless, besides different materials and different electrochemical protocols, the impact of the geometry and various parameters of the setup on the recorded dissolution signal has not been studied until now. Such parameters can influence the results obtained with an EFC-ICP-MS and thus the interpretation of the dissolution mechanism and/or stability assessment. Hereby, we demonstrate that the length of the tubing between the outlet of the cell and the inlet of the ICP-MS impacts the resolution of the PtCo catalyst dissolution peaks. This, in turn, facilitates studies where the detection of extremely low concentrations is necessary, such as under a very narrow potential window. Similarly, a reduced internal volume of the cell restricts Pt redeposition, contributing to a more precise evaluation of stability. These claims were supported by dynamic continuum mechanics modelling of the ion concentration in a model EFC. Finally, we provide guidelines and advice to properly measure dissolution with an electrochemical cell coupled with ICP-MS.

Digital fluency – a dynamic capability continuum

The impact of digital technologies on the ways people work, learn and live has been debated and researched for half a century. Digital literacy approaches have recurrently been the focus of educational and industry learning; however, current framings of digital literacy are not sufficient to support students’ digital capability development, nor do static digital literacies reflect the dynamic and contextual nature of digital capabilities. A digital capability continuum that fluidly moves between digital foundation skills, digital literacies and digital fluency is a more robust model for education. By unpacking the digital capability continuum and responding to both learning and curriculum paradigms, this paper expands on an earlier framework (Coldwell-Neilson, 2020), the decoding digital literacy framework, as well as building on our research and academic experiences, to inform higher education. A key agenda is that the higher education sector frames digital fluency as a mindset and an attitude. The model and framework underscore that capabilities need to be flexible and transferable across technologies, disciplines and the world of work.

Semantic Field "Catasprophe" in Alternative Worldviews: A Quantitative Dimension

The paper addresses language units that constitute semantic space "catastrophe" within alternative English-mediated worldviews. Designation units synonymic or contextually related to catastrophe / disaster, were chosen from the Web 2021 (enTenTen21) corpus suggested by the Sketch Engine and from the custom corpus of present-day rock lyrics processed via the Ant.Conc 3.5.8 tools. The content of the respective concept is considered through the prism of a logical model that addresses an entropic irrevocable transformation of an open system. He paper focuses on the comparative analysis of the space's composition in two worldview variants. The structure of the semantic space is identified as a field, i.e. a dynamic volumetric continuum that sports multi-level organization as well as each level's zonal segmentation. Special attention is paid to functional-semantic and semiotic properties of the space-field's components. The article employs an interdisciplinary approach that encompasses the myth-oriented semiosis theory and broad inter-systemic analogies ("M-logic").

Dynamic energy-minimization multi-scale heterogeneous continuum evolution model for gas-solid fluidization

Traditional gas–solid continuum model is still computationally inaccurate and physically unreasonable, due to a homogeneous assumption that particles are uniformly dispersed in a computational grid. Therefore, its application to simulate industrial gas–solid fluidization needs further improvement. Here, a novel heterogeneous continuum model, named dynamic energy-minimization multi-scale (EMMS) evolution model, was developed for accurate and fast simulations of gas–solid fluidization systems. In this model, the evolution of gas–solid heterogeneous multiscale structure in each computational grid was directly resolved by EMMS model, which was then coupled with multiphase mixture model to dynamically calculate phase holdup and flow field. Both S-shaped axial voidage profiles and spatial distribution of solid phase with the presence of a core-annulus structure were successfully captured. Compared with two-fluid model, dynamic EMMS evolution model showed great advantages in various aspects, including (a) model accuracy: predicted “S” type distribution of bed voidage was closer to experimental data; (b) stability: a rather larger time step of 0.1 s could be used; and (c) computational cost: dynamic EMMS evolution model was 245 times faster than two-fluid model. Based on dynamic EMMS evolution model, the complex multiscale hydrodynamics can be well simulated and understood, and will help the design and scale-up of large-scale gas–solid fluidized bed reactors.

Roots seeking of multiple shear-bands in amorphous alloys at the atomic scale

The propagation of shear-bands is of utmost importance in understanding the macro and microscopic deformations of bulk metallic glasses (BMGs). In this study, using molecular dynamics simulations to elucidate the intricate atomic-scale mechanisms governing dynamic continuum shear-bands and microstructural evolution during deformation. This work provides compelling evidence of self-organized critical behavior, as evidenced by the observation of serrated flow patterns and distributions of elastic energy density. Moreover, we unveil the influence of notch length on the principal shear-band based on the steep stress drop (i.e., Δτ =τy-τs, distinct from serrated flows), strength-normalized difference (i.e., Δτ/τy), and probability distribution of shear-strain. The effective blocking of shear bands by nanocrystal second phase can be attributed to the synergistic reinforcement effect of dislocations and nano-stacking faults. Finally, the analysis of the serrated flow behavior and stress-increment distribution during nanoindentation establishes the connection between micromechanical behavior, shear-band evolution, and macroscopic mechanical properties.

Emergence and growth of faults during earthquakes: Insights from a dynamic elasto-plastic continuum model

I use a dynamic two-dimensional plane strain model of an elasto-plastic (Mohr-Coulomb) material with velocity-weakening friction to numerically simulate the emergence and propagation of shear fractures that accumulate slip intermittently during earthquakes. The model considers a 10 × 10 km block of homogeneous crust with a small weak inclusion, subjected to slow simple shear. Results show that deformation is distinctly bimodal, consisting of long periods (lasting ca. 50–200 years) where deformation is dominantly elastic separated by rapid sliding events lasting a few seconds during which time deformation is strongly localised on narrow plastic shear bands (faults). In terms of energy expenditure, the interseismic period is overwhelming dominated by accumulation of elastic strain energy whereas during earthquakes, most of the drop in elastic strain energy is consumed (dissipated) by plastic work. Model earthquakes have maximum slip rates of a few meters per second, involve a few meters of slip and result in drop of mean differential stress of several megapascals. Most earthquakes are complex events involving near-simultaneous rupture of multiple fault segments that propagate at supershear velocities (close to the P-wave speed) while they also induce a significant amount of more diffuse off-fault inelastic deformation. Earthquakes may involve formation of new faults and/or reshear on previously formed faults, which are favourably reactivated owing to their low pressure. Most individual faults establish much of their length early, whereas during subsequent events they continue to accumulate displacement at virtually constant length. As the confining pressure is increased, ruptures are more dynamic, which leads to increasingly widespread inelastic deformation. Overall, the models highlight the complex temporal and spatial interactions that exist between different faults within an array that communicate especially during earthquakes through static and dynamic changes in the stress field.

The effect of inhibitory control and language proficiency on intra-sentential switching costs in reading comprehension

Based on the inhibition account and activation account, inhibitory control and language proficiency play big roles on language control mechanisms underlying language switching respectively. But it is still debatable whether inhibitory control and language proficiency play roles in sentential context during bilingual language comprehension, and how and when they work if they both do. The present study examined the specific roles of language proficiency and inhibitory control on modulating intra-sentential switching costs in Chinese-English bilinguals using self-paced reading task. Results indicated that language proficiency and switching direction modulated intra-sentential switching costs significantly. Switching costs were larger when switching into L1 than into L2 for the first two code-switched words due to inhibitory effect, but more costly switching into L2 than into L1 since the third code-switched words owing to the effect of relative language proficiency. During bilingual language processing, inhibition and activation of languages shaped a dynamic interplay of complementary language control processes. Specifically, inhibitory control and language proficiency work as a dynamic continuum in language switching at sentence level. Switching into L1 requires the release of inhibition to L1, but switching into L2 asks the activation and access of L2. The interaction effects of language proficiency and inhibitory control influenced the exertion and components of inhibition. This study reconciled the independent roles of language proficiency and inhibitory control on language switching and constructed a new continuum based on language proficiency.

Cognitive Psychology: As essential & integrated part of medical education w.s.r. to Yukti Pramana in Ayurveda

Growth of any knowledge base depends on a dynamic continuum of a tripod of creating new knowledge through research, effective transfer of knowledge through proactive education and utilization of the knowledge with good professional practice. A set of knowledge system is likely to be relative to time & place setting which facilitates its need based development. But though Ayurvedic education system is one of the recognized age old education systems but still neither developed nor advanced alike other education system across the globe. Due to lack of maintenance of such dynamic continuum in current education system of ancient system of Indian medicine, the knowledge bases of Ayurveda becomes stagnant, static & gradually pass into merely history &may not remain dynamic & useful. Need of dynamism and activism through incorporation of cognitive psychology in education curriculum and enhancement of reasoning skill followed by critical thinking in the mind of medical professionals is quite necessary in the field of Ayurveda to make it up to date and develop it further in tune with the changing needs of the society today. Keeping this in view an effort has been made by the author to explore the concept of Yukti as key element of cognitive psychology make its relevant application in the field of current teaching & education and practice of Ayurved worldwide.

Investigation of electrostatically tunable adhesion and instability of flying head slider

The interfacial adhesion between microstructures is inevitable in a micro-electro-mechanical system (e.g., hard disk drive (HDD)), which may lead to complicated microtribodynamics problems. This research has investigated the effect of surface potential on the interfacial adhesion and microtribodynamics of the head–disk interface (HDI) in an HDD. A dynamic continuum surface force model, where the electrowetting is considered, is proposed to evaluate the interfacial interaction, and then employed into a two-degree-of-freedom (2DOF) model to theoretically analyze the potential influence mechanism on the microtribodynamics. The results confirm that the elimination of potential can effectively repress the adhesion retention, which is further proved by the measured slider response with a laser Doppler vibrometer (LDV). Moreover, the effect of the potential on the adhesion-induced instability is also analyzed through the phase portrait. It tells that the critical stable flying height can be lowered with the elimination of potential.

Addressing Complexity in Chronic Disease Prevention Research

There is wide agreement on the need for systems thinking to address complexity in chronic disease prevention but there is insufficient understanding of how such approaches are operationalised in prevention research. Ison and Straw propose that to address complexity, the right balance must be struck between ‘systemic’ and ‘systematic’ paradigms. We examined the nature and characteristics of this relationship in a series of six qualitative case studies of prevention research. Data comprised 29 semi-structured interviews with 16 participants, and online documents. The analysis combined inductive methods from grounded theory with a theoretically informed framework analysis. Systemic and systematic ways of working varied across each case as a whole, and within the dimensions of each case. Further, the interplay of systemic and systematic approaches was described along a dynamic continuum of variable proportions, with greater emphasis on systemic aspects balanced by less focus on the systematic, and vice versa. By expanding the boundaries for exploring prevention research, we gained empirical understanding of the potential and scope of systemic and systematic paradigms for addressing complexity in prevention research. There is inherent value in being more explicitly conscious and bilingual in both systemic and systematic paradigms so that their respective value and strengths may be utilised. Our findings propose a coherent theoretical frame to better understand existing approaches for addressing complexity in prevention research.

The Diversity of Astrocyte Activation during Multiple Sclerosis: Potential Cellular Targets for Novel Disease Modifying Therapeutics.

Neuroglial cells, and especially astrocytes, constitute the most varied group of central nervous system (CNS) cells, displaying substantial diversity and plasticity during development and in disease states. The morphological changes exhibited by astrocytes during the acute and chronic stages following CNS injury can be characterized more precisely as a dynamic continuum of astrocytic reactivity. Different subpopulations of reactive astrocytes may be ascribed to stages of degenerative progression through their direct pathogenic influence upon neurons, neuroglia, the blood-brain barrier, and infiltrating immune cells. Multiple sclerosis (MS) constitutes an autoimmune demyelinating disease of the CNS. Despite the previously held notion that reactive astrocytes purely form the structured glial scar in MS plaques, their continued multifaceted participation in neuroinflammatory outcomes and oligodendrocyte and neuronal function during chronicity, suggest that they may be an integral cell type that can govern the pathophysiology of MS. From a therapeutic-oriented perspective, astrocytes could serve as key players to limit MS progression, once the integral astrocyte-MS relationship is accurately identified. This review aims toward delineating the current knowledge, which is mainly focused on immunomodulatory therapies of the relapsing-remitting form, while shedding light on uncharted approaches of astrocyte-specific therapies that could constitute novel, innovative applications once the role of specific subgroups in disease pathogenesis is clarified.

Risks and opportunities of digitally mediated interactions: young people’s meanings and experiences

ABSTRACT Young people’s digitally-mediated interactions entail negotiating co-existing risks and opportunities. This paper discusses youth perspectives on these risks and opportunities, based on data from focus groups conducted with 12–21-year-olds in England. Analysis of examples of digitally-mediated interactions shared by participants suggests that pursuing opportunities involved or created risk for oneself and/or others, while motivations to pursue opportunities were shaped by risks resulting from the actions of others. Flows of risk and opportunity were, therefore, reciprocal across a dynamic continuum of ‘digital’ – ‘non-digital’ contexts and relational both for and between young people. It is argued that a reciprocal and relational conceptualisation of ‘post-digital’ negotiations of risk and opportunity among youth facilitates critical engagement with their accounts of their online lives as well as identification of the interconnections between individual, interpersonal and community-ethical spheres of meaning and experience.

Modelling transient stresses in dynamically loaded elastic solids using the Lattice Boltzmann Method

AbstractIn solids subjected to transient loading, inertial effects and S‐ or P‐wave superposition can give rise to stresses which significantly exceed those predicted by quasi‐static models. It pays to accurately predict such stresses – and the failures induced by them – in fields from mining to automotive safety and biomechanics. This, however, requires costly simulations with fine spatial and temporal resolutions.The Lattice Boltzmann Method (LBM) can be used as an explicit numerical solver for certain appropriately formulated conservation laws [1]. It encodes information about the field variables to be simulated in distribution functions, which are modified locally and propagated across a regular lattice. As the LBM lends itself to finely discretised simulations and is easy to parallelise [2, p.55], it is an intriguing candidate as a solver for dynamic continuum problems.Recently, Murthy et al. [3] and Escande et al. [4] adopted LBM algorithms to model isotropic, linear elastic solids. We extended these algorithms using local boundary rules that allow us to model arbitrary‐valued Dirichlet and Neumann boundaries. Here, we illustrate applications of the LBM for solids and the proposed additions by way of a simple numerical example – a glass pane subject to a sudden impact load.

Bilevel optimization of a housing allocation and traffic emission problem in a predictive dynamic continuum transportation system

AbstractIn recent decades, the effects of vehicle emissions on urban environments have raised increasing concerns, and it has been recognized that vehicle emissions affect peoples’ choice of housing location. Additionally, housing allocation patterns determine people's travel behavior and thus affect vehicle emissions. This study considers the housing allocation problem by incorporating vehicle emissions in a city with a single central business district (CBD) into a bilevel optimization model. In the lower level subprogram, under a fixed housing allocation, a predictive dynamic continuum user‐optimal (PDUO‐C) model with a combined departure time and route choice is used to study the city's traffic flow. In the upper level subprogram, the health cost is defined and minimized to identify the optimal allocation of additional housing units to update the housing allocation. A simulated annealing algorithm is used to solve the housing allocation problem. The results show that the distribution of additional housing locations is dependent on the distance and direction from the CBD. Sensitivity analyses demonstrate the influences of various factors (e.g., budget and cost of housing supply) on the optimized health cost and travel demand pattern.

Lateral kinematic response of offshore pipe piles to S‐wave seismic excitation

AbstractThis paper presents an analytical study on the lateral kinematic response of offshore pipe piles subjected to vertically propagating S‐wave seismic excitation. Both the kinematic interaction of the pipe pile with the soil and seawater are considered. The lateral resistances of the outer and inner soil are obtained based on the confined viscoelastic dynamic continuum models, while the hydrodynamic pressures of the seawater are based on the inviscid incompressible fluid theory. The pile response is then obtained by utilizing the continuity condition at the soil‐pile and seawater‐pile interfaces along the pile shaft. The derived solution is employed to investigate the sensitivity of the seismic response of pipe piles to certain key problem parameters, such as length of pile segment embedded in seawater, the relative stiffness of the pile and soil and the pile radius ratio. We demonstrate that the partially embedded piles are much more flexible compared with fully embedded piles when subjected to S‐wave excitation, resulting more strong motion transferred to the superstructures and the existence of seawater will amplify the seismic responses of offshore pipe piles.

Horizontal dynamic response of offshore large-diameter pipe piles

The dynamic response of an offshore large-diameter pipe pile-soil-water system under horizontal dynamic loads is analytically studied in this paper. The hydrodynamic pressure of the outer and inner seawater are obtained by the inviscid compressible fluid theory, and the lateral resistances of the outer and inner soil are obtained based on the viscoelastic dynamic continuum models. The pile response is obtained by utilizing the continuity conditions at the soil-pile and seawater-pile interfaces along the pile shaft. Results of the proposed solution are validated against FEM numerical results and against existing analytical and experimental results. The effects of hydrodynamic pressure from seawater on the pile head displacement and on the natural frequency are subsequently investigated for different problem parameters. Finally, the sensitivity of horizontal dynamic responses of the pipe pile-soil-water system in the frequency range to certain key parameters, such as water depth, pile length above the seawater, thickness of the soil, outer and inner radius of the pipe pile is analyzed.