Local Boundary Research Articles

Blow-up for a Porous Medium Equation with Local Linear Boundary Dissipation

This article investigates the blow-up behaviors for a porous medium equation with a superlinear source and local linear boundary dissipation. Making use of the concavity method, we establish sufficient conditions to guarantee the occurrence of the finite time blow-up phenomenon. Meanwhile, we show the existence of the finite time blow-up solutions for arbitrarily high initial energy. Finally, we derive the life span bounds (i.e., the lower and upper bounds of the blow-up time).

Turbulent activity in the near-wall region of adverse pressure gradient turbulent boundary layers

Two direct numerical simulation (DNS) databases are investigated to understand the effect of the outer-layer turbulence on the inner layer’s structures and energy transfer mechanisms. The first DNS database is the non-equilibrium adverse-pressure-gradient (APG) turbulence boundary layer (TBL) of Gungor et al. [1]. Its Reynolds number and the inner-layer pressure gradient parameter reach above 8000 and 10, respectively. The shape factor spans between 1.4 and 3.3, which indicates the flow has various velocity defect situations. The second database is the same flow as the first one but the outer layer turbulence is artificially eliminated in this flow. Turbulence is removed above 0.15 local boundary layer thickness. For the analysis, we chose four streamwise positions with small, moderate, large, and very-large velocity defect. We compare the wall-normal distribution of Reynolds stresses, two-point correlations and spectral distributions of energy, production and pressure strain. The results show that the inner layer turbulence can sustain itself when the outer-layer turbulence does not exist regardless of the velocity defect or the pressure gradient. The two-point correlations of both cases show that outer large-scale structures affect the inner layer structures significantly. The streamwise extent of the correlation contours scales with pressure-viscous units. This shows the importance of the pressure gradient’s effect on the inner-layer structures. The spectral distributions demonstrate that the energy transfer mechanisms are probably the same in the inner layer regardless of the velocity defect, which suggests the near-wall cycle may exist even in very-large defect APG TBLs where the mean shear in the inner layer is considerably lower than small-defect APG TBLs.

Scaling and Localization in Multipole-Conserving Diffusion.

We study diffusion in systems of classical particles whose dynamics conserves the total center of mass. This conservation law leads to several interesting consequences. In finite systems, it allows for equilibrium distributions that are exponentially localized near system boundaries. It also yields an unusual approach to equilibrium, which in d dimensions exhibits scaling with dynamical exponent z=4+d. Similar phenomena occur for dynamics that conserves higher moments of the density, which we systematically classify using a family of nonlinear diffusion equations. In the quantum setting, analogous fermionic systems are shown to form real-space Fermi surfaces, while bosonic versions display a real-space analog of Bose-Einstein condensation.

What Is in a <unittitle>? Cross-lingual Topic Detection & Information Retrieval in Archives Portal Europe

Archives Portal Europe (APE, www.archivesportaleurope.net ) is the portal of European archives, an aggregator that connects on a single research point the catalogues and digitised archival material of all archives in and about Europe. It currently hosts material from more than 30 countries and from a variety of archival institutions (such as State archives, city archives, university and parish archives, private institutions, and more). It is maintained by the Archives Portal Europe Foundation, an international consortium of State archives and other archival institutions that aim to connect the archival material of single institutions into one digital repository to allow universal access to the archival heritage of Europe, promoting new forms of archival research beyond national or local boundaries. One of the research tools made available by Archives Portal Europe is by topics; however, these are currently maintained manually by the archivists, and the vast amount of archival material ingested in the portal makes it impossible to have a comprehensive body of topics that describe the whole of the APE repository. Archives are traditionally not organised by their subject content, but around the entity (person, organization, body) that created and/or collected the documents in the course of their activities. While this is an undisputed pillar of archival management, the availability of online digital repositories for archival research requires new tools for digital archival research, particularly when different archival traditions from different countries and different types of institutions are merged into a unique research portal. Topic detection becomes a fundamental tool to guide archival research and to allow archives to be accessible to potentially world-wide users in a situation where national and linguistics barriers blur or are re-defined. This article presents the preliminary results and plan for future iterations of an AI tool for automated topic detection in a multi- lingual environment, where human-created taxonomies act as bases for the algorithms to aggregate relevant material around a specific topic. The development is based on supervised machine learning, with a combination of human inputs in different languages, and of the usage of Wikipedia pages to model the relevant vocabulary and entities.

Atomic-Resolution In Situ Exploration of the Phase Transition Triggered Failure in a Single-Crystalline Ni-Rich Cathode.

Single-crystalline cathode materials LiNixCoyMn1-y-zO2 (x ≥ 0.6) are important candidates for obtaining better cyclic stability and achieving high energy densities of Li-ion batteries. However, it is liable to initiate phase transitions inside the grains during electrochemical cycling, and the processes and regions of these phase transitions have remained unknown. In this research, we conducted an intrinsic study, investigating the chemicals and microstructural evolution of single-crystalline LiNi0.83Co0.11Mn0.06O2 using in situ biasing transmission electron microscopy at an atomic scale. We observed that the layered structure on the surface of the single-crystalline material was degraded during the charging process, resulting in continuous phase transitions and the formation of surface oxygen vacancies, which can reduce both the structural and thermal stability of the material. Uneven delithiation led to the formation of high-density defects and discontinuous inactive electrochemical phases, such as local antiphase boundaries and the rock salt phase, in the bulk of the material. The non-uniformity of the structure and the coexistence of active and inactive phases introduce significant tensile stress, which can lead to intragranular cracks inside the grains. As the number of cycles increases, the structural degradation caused by the intragranular phase transition will further increase, ultimately affecting the cycling capacity and stability of the battery. This work has broad implications for creating lithium-ion batteries that are effective and long-lasting.

Uneven infection and government capacity: evidence from Shanghai lockdown

ABSTRACT In April, 2022 the government of Shanghai initiated a severe lockdown in which the city’s 25 million residents were required to remain in their apartment buildings for 2 months. During the lockdown, sub-district (‘Jiedao’) governments were responsible for implementing COVID policies and allocating basic goods to the residents within their local administrative boundaries. This paper documents a strong negative correlation between new COVID-19 infections and the distance to the sub-district boundaries. Such correlation is intensified when the government expenditures and goods accessibility are low. We argue that this pattern results from insufficient local government capacity to serve the entire sub-district; individuals near the boundary may evade regulations and seek private connections to obtain goods or services, thereby increasing their risk of being infected. Our results provide insight into government management in the pandemic context and offer new evidence that geography affects the implementation of government policy even at small local levels.

Effect of Cr and Ni on mechanical response and microstructural evolution of nanocrystalline ferrite: A molecular dynamics study

Microalloying plays a critical role in improving the mechanical properties of steel. To offer a better theoretical guide for experimental research at the atomic level, this paper investigated the synergistic mechanism of adding trace amounts of alloy Cr and Ni and the microstructure evolution of nanocrystalline ferrite during the mechanical response process. First-principles calculations were implemented to investigate electronic properties. Hybrid molecular dynamics and Monte Carlo simulations were employed to explore the deformation mechanism under uniaxial tension and scratching. Specifically, comprehensive differences between doped and pure nanocrystalline ferrites were explored regarding local stress-strain state, dislocation evolution, twin expansion, and grain boundary activity. The results show that Cr- and Ni-doped nanocrystalline ferrite has higher strength and better wear resistance. The potential mechanism is that the addition of Cr and Ni enhances the atomic bonding strength with Fe atoms, hinders the movement of dislocations caused by lattice distortion, and suppresses grain boundary slip and migration, thereby improving the resistance to plastic deformation and grain boundary stability. Theoretical calculations based on microstructure indicate that compared to solid solution strengthening, Ni-induced grain boundary strengthening plays a dominant role in improving yield strength. Under large deformation, the trend of mechanical response is reversed. The suppression of dislocation motion by Cr reduces the dislocation density and dislocation entanglement, resulting in flow stress and local scratch force being smaller than that of pure samples. However, the formation of more nanoscale twins and twin-dislocation interactions enhances strain-hardening ability during tensile. Finer nanostructured subgrains are formed under scratching. These results provide valuable insights into the understanding of the strengthening mechanism and plastic deformation mechanism of Cr-Ni system low alloy steel under dynamic loading.

‘Could have been a god but chose to be a Devil’. The 2004 European Championships and Wayne Rooney’s departure from Everton Football Club

ABSTRACT The world of elite football is woven from complex and intriguing relations informing the identities of players, clubs and supporters, across local, national and international boundaries. Often, key players with a global presence become a catalyst informing such relations. This paper considers one stark example of this: the case of Wayne Rooney, a local Liverpool lad and football protégée who raced through the ranks of Everton’s youth academy to establish himself in the first team aged sixteen before being transfered to Manchester United in the summer of 2004 for a fee of £30 million. The paper describes how, set in the wider context of tense dynamics between club and country and between local and national sentiment, the specific manner in which the transfer unfolded pitched Rooney at the centre of an identity defining power struggle between clubs, agents and fans.

Multi-view orientational attention network combining point-based affinity for polyp segmentation

Most existing deep learning-based polyp segmentation methods neglect two important aspects of polyps: the geometric orientation information of polyps and the point information of the entire colonoscopy area. In this paper, we introduce a multi-view orientational attention network (MVOA-Net), which incorporates orientation and point awareness to effectively address the issue of intra-class inconsistency resulting from variations in polyp shape, size, and position, as well as the inter-class indistinction caused by the high similarity between polyp lesions and surrounding tissues. To achieve robust orientation awareness, we propose a novel geometric orientation transformer encoder (GOTE) based on horizontal and vertical views. Moreover, To simultaneously capture the global context information of GOTE and emphasize the important local information of the convolution-based attention encoder (CBAE), a global and local cross attention fusion module (CAFM) is also proposed to simultaneously model the long-range dependencies of polyps and pay sufficient attention to the local boundaries of polyps. Additionally, a efficient atrous spatial pyramid pooling (E-ASPP) module is proposed to enhance the semantic representation of high-level features. Finally, a point-based affinity module (PBAM) and a multi-scale fusion module (MSFM) are proposed to distinguish the disguise of polyps, further alleviating inter-class indistinction. The ablation study results demonstrate the effectiveness of each component. Quantitative and qualitative experimental results show that MVOA-Net achieves the best segmentation accuracy across domain polyp datasets and has obvious advantages in segmenting multiple polyp objects.

Structural and morphological organization of dry valley of the Cretaceous south of the Central Chernozem Region

The peculiarities of origin, morphological and genetic varieties and structural and dynamic interrelations of dry valley landscapes of the Cretaceous south of the Central Chernozem Region are considered. Modern ideas about genesis, morphology, development and landscape structure of sukhodols are presented. Paradynamic interrelations of structural elements of basin landscape systems are emphasized. The necessity of taking into account landscape specificity of dry lands when solving the problems of nature management and optimization of landscape-ecological situation in the Cretaceous south of the Central Chernozem Region is emphasized. As an example, we analyzed the component, territorial and altitudinal organization of natural complexes of a large sukhodols of the Kuvshin dry valley located in the Podgorensky district of the Voronezh Region. The main factors of landscape differentiation are established, among which are peculiarities of morpholithogenic base, character of biostrom development, modern economic use. The problems of identification of local landscape boundaries and approaches to their solution have been noted. Based on the results of the research, 7 families and 45 species of landtypes, as well as altitudinal landscape layers and sub-layers were identified within the valley. Recommendations on changing the conservation status of the territory are given.

Well posedness of linear parabolic partial differential equations posed on a star-shaped network with local time Kirchhoff's boundary condition at the vertex

The main purpose of this work is to provide an existence and uniqueness result for the solution of a linear parabolic system posed on a star-shaped network, which presents a new type of Kirchhoff's boundary transmission condition at the junction. This new type of Kirchhoff's condition - that we decide to call here local-time Kirchhoff's condition - induces a dynamical behavior with respect to an external variable that may be interpreted as a local time parameter, designed to drive the system only at the singular point of the network. The seeds of this study point towards a theoretical inquiry of a particular generalization of Walsh's random spider motions, whose spinning measures would select the available directions according to the local time of the motion at the junction of the network.

An Efficient Local Artificial Boundary Condition for Infinite Long Finite Element Euler–Bernoulli Beam

To solve the wave propagation problems of the Euler–Bernoulli beam in an unbounded domain effectively and efficiently, a new local artificial boundary condition technology is proposed. It replaces the residual right-hand side of the truncated discrete equation with an equivalent linear algebraic system. First, the equivalent Schrodinger equation is discussed. Its artificial boundary condition is obtained by first rationalizing the Dirichlet-to-Neumann condition in the frequency domain with a Pade approximation and then inverse transforming each Pade term back into the time domain by introducing auxiliary degrees of freedom. Frequency shifting is employed such that it performs better near a prescribed frequency. Then, the artificial boundary condition of the finite element Euler–Bernoulli beam is obtained by simple algebraic manipulations on that of the corresponding Schrodinger equation. This method only makes local changes to the original truncated discrete dynamic system and thus is very efficient and easy to use. The accuracy of the proposed method can be improved by using more Pade terms and a proper shift frequency. The numerical example shows, with only a few additional degrees of freedom, the proposed artificial boundary condition effectively eliminates the spurious reflection. The idea of the proposed method can also be used in other dispersive wave systems.

The Pannon LitH2Oscope magnetotelluric array in the Pannonian Basin

The Pannonian Basin is one of the best natural laboratories in the world to study the lithospheric response to continental extension and subsequent tectonic inversion. Here we address the topic of lithospheric structure by a combined geochemical and magnetotelluric analysis, which has been carried out in the framework of the Pannon LitH2Oscope project. The main objective was to detect the resistivity distribution over the entire lithosphere by magnetotelluric measurements, considering the lithological resistivity properties and relate the results to the structure and evolution of the Pannonian Basin. The Pannon LitH2Oscope MT array was used to estimate the depth of the Lithosphere-Asthenosphere Boundary (LAB), considering the legacy MT data and compared to previous estimates for the region. Using the MT and geomagnetic response functions, major structural zones of the Pannonian basin, such as the Mid-Hungarian Shear Zone or fault systems like the Makó Trough and the Békés Basin, were also imaged. In addition, we used the apparent resistivity soundings to compare 1D resistivity models computed from geochemistry and obtained from field MT measurements. This comparison provided new constrains for the composition, fluid and melt content variations at the local lithosphere-asthenosphere boundary. The Pannon LitH2Oscope MT dataset and the results presented in this paper provide input for more complex 3D inversions and further investigations of the lithospheric structure in the Carpathian-Pannonian region.

Experimental investigation of hypersonic boundary layer instability with wavy wall located downstream of synchronization point

The wavy wall surface has been reported to be effective in suppressing the growth of second mode instability waves in hypersonic boundary layer, while the allocation of wavy wall relative to the synchronization point requires further study. Upon this work experimental investigation of hypersonic boundary layer instability with wavy wall located downstream of synchronization point based on 7° half-angle sharp cone at zero angle of attack was carried out in a hypersonic noisy wind tunnel. The evolution of instability waves with wavy wall surface is measured using both surface-mounted pressure fluctuation sensors and focused laser differential interferometer (FLDI). The results reveal that the growth of instability waves has been enhanced significantly when the wavy wall region is allocated downstream of the synchronization point when the wavy wall height is slightly smaller than the local boundary layer thickness. Additionally, second mode instability waves are observed at both crests and troughs within the wavy wall region based on the FLDI measurement and moreover, the high-frequency instability waves measured in the separation bubbles of troughs are speculated to be the transmission of second mode instability waves from the shear layer, rather than the local generation of second mode instability.

Analytical approach to solving linear diffusion–advection–reaction equations with local and nonlocal boundary conditions

Initial–boundary value problems for a linear diffusion–advection–reaction equation are considered, with general nonhomogeneous linear boundary conditions and general linear nonlocal boundary conditions. Analytical solutions are obtained using an embedding method. The solutions are expressed in terms of time‐varying functions that satisfy coupled linear Volterra integral equations of the first kind. A boundary element method is applied to numerically solve the integral equations. Three examples are given to demonstrate the accuracy of the numerical solutions when compared with the analytical solutions. The embedding method is applicable to problems with bounded and unbounded spatial domains.

Existence and Uniqueness of Solutions for Fractional-Differential Equation with Boundary Condition Using Nonlinear Multi-Fractional Derivatives

In this article the existence as well as the uniqueness (EU) of the solutions for nonlinear multiorder fractional-differential equations (FDE) with local boundary conditions and fractional derivatives of different orders (Caputo and Riemann–Liouville) are covered. The existence result is derived from Krasnoselskii’s fixed point theorem and its uniqueness is shown using the Banach contraction mapping principle. To illustrate the reliability of the results, two examples are given.

State labeling's impact on geographic boundaries of local

AbstractLocal labeling is an important issue within the horticultural industry as many producers have devoted considerable resources to advertising their products as local. Further, all states have implemented some form of local labeling program to increase local purchasing. As states expand the reach of these programs, the programs begin to compete as awareness and perception move across state lines. Using an online survey to study consumers in the Southeastern United States, we look to identify how state labeling programs are viewed in nearby states. Notably, we assess awareness, perception, and its impact on the local definition of these programs in their “home” state as well as nearby states. Specifically, we evaluate the impact of nine Southeastern state‐level branding programs. Our results indicate that consumers are more aware of their home state's local label, but awareness does exist for other states' labels. We also find that a home state label moves some consumers to a more state‐level local boundary, while seeing another state's label increases the boundary for what is perceived as local [EconLit Citation: Q13].

Study on local strain distribution and grain boundary characteristics of tensile-deformed TRIP-assisted medium manganese steel

The current study emphasizes the local strain distribution and grain boundary characteristics of tensile-deformed Fe-6.72Mn-3.92Al-0.18C medium manganese steel (MMnS), which has undergone thermomechanical processing followed by intercritical annealing at various temperatures (700, 750 and 800 °C for 1 h). Microstructural examination through electron backscattered diffraction (EBSD) analysis is executed to evaluate the local strain distribution, and grain boundary misorientation before and after the tensile test. In the annealed samples, the Kernel average misorientation (KAM) of the face-centered cubic (FCC) phase is close to 0°, indicating strain-free austenite grain formation. Before the tensile test, the body-centered cubic (BCC) phase is relatively free from local strain; however, as the misorientation increases due to tensile deformation, the BCC/FCC interphase boundaries become highly strained. The sum of the fraction of low-angle grain boundaries (ΣLAGBs) decreases with an increase in annealing temperature, while the sum of fractions of misorientation greater than 15°, excluding coincident site lattice (CSL) boundaries, increases moderately. With an increase in annealing temperature, the sum of the CSL special boundary fractions (Σ3 and Σ9) increases considerably. The weighted average density of LAGBs in the BCC phase is higher in the sample annealed at 700 °C compared to the other annealed samples. The increase in the fraction of LAGBs in the FCC phase during tensile deformation is due to the significant transformation-induced plasticity (TRIP) effect and high austenite transformation ratio. Crack formation, propagation, and branching and blunting in the tensile-tested 750 °C-annealed sample are examined by the EBSD analysis. Crack propagation is hindered by the existence of γ-fiber texture components and high-angle grain boundaries in the sample annealed at 750 °C.

Shapelet-based orientation and defect identification method for nanostructured surface imaging

Structure-property relations are of fundamental importance for continued progress in materials research. Determining these relationships for nanomaterials introduces additional challenges, especially when nanostructure is present, either through self-assembly or nano-lithographic processes. Recent advances have been made for quantification of nanostructured surfaces, for which many robust experimental imaging methods exist. One promising approach is based on the use of shapelet functions for image analysis, which may be used as a reduced basis for surface pattern structure resulting from a broad range of phenomena (e.g. self-assembly). These shapelet-based methods enable automated quantification of nanostructured images, guided by the user/researcher, providing pixel-level information of local order without requiring detailed knowledge of order symmetries. In this work, enhancements to the existing shapelet-based response distance method are developed which enable further analysis of local order, including quantification of local orientation and identification of topological defects. The presented shapelet-based methods are applied to a representative set of images of self-assembled surfaces from experimental characterization techniques including scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. These methods are shown to be complementary in implementation and, importantly, provide researchers with a robust and generalized computational approach to comprehensively quantify nanostructure order, including local orientation and boundaries within well-aligned grains.

General Local Reactive Boundary Condition for Dissolution and Precipitation Using the Lattice Boltzmann Method

AbstractA general and local reactive boundary condition (RBC) for studying first‐order equilibrium reactions using the lattice Boltzmann method is presented. Its main characteristics are accurate reproduction of wall diffusion, invariance to the wall and grid orientation, and absence of nonphysical artifacts. The scheme is successfully tested for different benchmark cases considering diffusion, advection, and reactions of fluids at solid‐liquid interfaces. Unlike other comparable RBCs from the literature, the novel scheme is valid for a large range of Péclet and Damköhler numbers, and shows realistic pattern formation during precipitation. In addition, quantitative results are in good accordance with analytical solutions and values from literature. Combining the new RBC with the rest fraction method, Péclet‐Reynolds ratios of up to 1,000 can be achieved. Overall, the novel RBC accurately models first‐order reactions, is applicable for complex geometries, and allows efficiently simulating dissolution and precipitation phenomena in fluids at the pore scale.