Single Boundary Research Articles

Effects of magnetic field on the anodic dissolution of alloy 690 in NaCl + Na2S2O3 solution

Purpose The purpose of this paper is to study the anodic dissolution processes of alloy 690 in NaCl + Na2S2O3 solutions by using digital holography. Design/methodology/approach The digital holography technique was used to in situ observe the dynamic processes occurring at the electrode|electrolyte interface during the anodic dissolution of alloy 690 in NaCl + Na2S2O3 solutions, both in the presence and absence of a magnetic field (MF). Findings In 3.5% NaCl + 0.01 M Na2S2O3 solutions, MF inhibited intergranular corrosion (IGC) because it increased the defects in the oxide film and facilitated the uniform adsorption of low concentration of S on these defects due to its stirring effects, which resulted in a weakened adsorption of S at the grain boundaries. Conversely, in 3.5% NaCl + 0.1 M Na2S2O3 solutions, MF promoted IGC by increasing the number of defects in the oxide film, with lots of S species preferentially adsorbing at the grain boundaries. The resultant salt films formed more readily, inhibiting the formation of the oxide film at the grain boundaries. Originality/value Through the use of digital holography, it was possible to in situ observe the initiation of IGC at a single grain boundary and its progression to adjacent grain boundaries, regardless of the presence or absence of MF.

Domain sampling methods for an inverse boundary value problem of the heat equation

Abstract We investigate the reconstruction of an unknown cavity inside a heat conductor with only single boundary measurement, which is a typical non-destructive testing of defects in material science using thermography. Mathematically, it can be formulated as an inverse boundary value problem for the heat equation. Two domain sampling methods, i.e., the range test (RT) and no-response test (NRT), are developed to realize the reconstruction. We first justify the convergence of the RT, which is based on the analytical extension property of solutions to the heat equation. Then we prove the duality of the RT and NRT by looking at the relation between their indicator functions. Consequently, the unknown cavity can be reconstructed by using either the RT or NRT if the solution associated to the single measurement cannot be analytically extended across its boundary. Next, we design two efficient algorithms for the RT and NRT to reconstruct the unknown cavity numerically. Each algorithm consists of two steps. The first step is to determine an approximation of the unknown cavity by implementing the sampling methods in a coarse grid, while the second step is to improve the reconstruction by using a fine grid in the approximate domain. The numerical results suggest that both algorithms can generate some rough information on the cavity with only one boundary measurement. Finally, by using this information as an initial guess for Newton's method, we improve the accuracy of the mentioned reconstruction results.

Analytical solution for one-dimensional chemo-hydro-mechanical coupled consolidation under time-dependent loading in buffer clay layer

An analytical method is developed for solving the coupled chemo-hydro-mechanical consolidation in a clay buffer layer under time-dependent loading. The coupled governing equations for the chemo-hydro-mechanical process are established in the time and spatial domain first. Then the governing equations are decoupled into two partial differential equations by introducing two variables. The analytical solutions corresponding to ramp and exponential loadings are finally derived based on the initial and boundary conditions. The developed analytical solutions are verified via comparing with the numerical results simulated by COMSOL Multiphysics. Based on the developed solutions, selected parametric study is carried out to investigate the influence of major parameters and hydraulic boundary conditions on the contaminants transport and pore water pressure dissipation in buffer clay layer. The results show that the major parameters have effects on the generation and dissipation of pore pressure, while only effective coefficient of diffusion, coefficient of ultrafiltration and relative change of total density of pore liquid significantly affect the contaminant migration process. Compared with a single drainage boundary, the pore pressure dissipation and contaminant migration in a double drainage soil layer are much faster. The longer the loading time of mechanical loading, the more significant the negative pore pressure caused by the concentration gradient.

Rihi Mesh Placement Algorithm In Collocation Methods

Various adaptive mesh selection strategies for solving single higher order two-points boundary value problems (BVPs) by using collocation methods are intensively investigated for along time and they are now well established. In this work we concern with numerical investigations of adaptive mesh selection algorithms using the criterion function rihi for solving first order system of BVPs and developing some algorithms. The algorithms perform quite nicely and appear competitive with De Boor algorithm.

Exploring the optimal boundaries of intellectual property rights and environmental regulation for enhancing technological innovation: a perspective of boundary effects in China

ABSTRACT This paper examines how the protection boundary of intellectual property rights and the implementation boundary of environmental regulation affect technological innovation from the perspective of boundary effects. We find that intellectual property rights, environmental regulation and technological innovation have an inverted U-shaped relationship, and there is a single optimal boundary value for each variable, forming a strong protection boundary and a weak protection boundary. We also find that choosing the appropriate boundary of intellectual property rights and environmental regulation can enhance technological innovation; intellectual property rights within the optimal boundary can extend its positive incentive effect on technological innovation. Environmental regulation uses intellectual property rights as the internal driving force, and with the help of intellectual property rights, continues to promote technological innovation. And the shielding effect of boundaries is greater than the intermediary effect. Our analysis of regional heterogeneity in intellectual property protection reveals that the integration of dual policy types is more effective in the eastern and central regions. Furthermore, the boundary of intellectual property protection in the eastern region surpasses that in the central region. It has important policy implications for promoting innovation system reform and coordinating high-quality economic development and high-level ecological environment protection.

Investigation of the wind loads and flow patterns of a high-rise building under twisted wind flows based on LES

The twisted wind effect has attracted increasing attention among scholars due to its significant influence on the wind loads and wind induced responses of high-rise buildings. Nowadays, it is still challenging to simulate twisted wind flows (TWFs) with larger wind twist angles (WTAs) in the wind tunnel test. Compared to wind tunnel test limitations, the large eddy simulation (LES) offers an effective tool to simulate a broader WTA range. Several state-of-the-art numerical studies have generated TWFs that rely on multiple velocity inflow boundary (MVIB), but it results in vast computational domains and substantial abnormal pressure fluctuations. This paper proposes a single velocity inflow boundary (SVIB) method for modeling TWFs, which can significantly reduce the computational domain size without losing accuracy. Based on the SVIB method, we simulate TWFs with four WTAs (i.e., 0°, 25°, 35°, 45°) and conduct a comprehensive analysis of the influence of WTA and wind direction angle on both the wind load characteristics of and the flow patterns around a high-rise building. The results show that the TWFs will twist the vortex topology and trajectory, and the maximum extreme local resultant force coefficient under 35TWF is larger than that under SWF by around 10 %. The positive and negative wind pressures can simultaneously occur on a special surface at large WTAs (e.g., 35°, 45°), which may impose significant shear forces on the intermediate layers. The wind veering effect enhances the contribution of vortex shedding to the longitudinal fluctuating wind loads and the influence of incoming turbulence on lateral fluctuating wind loads. This study contributes to providing a more effective LES method to simulate TWFs with large WTAs and to reveal the effect of large WTA on the wind load characteristics of high-rise buildings under TWFs and the underlying flow mechanism, which is beneficial to the future wind-resistant design of skyscrapers.

Study on microstructure characterization of steel using on multi-frequency electromagnetic detection and FE simulation calculation

Microstructures dominate mechanical properties of steel materials. Monitoring and controlling microstructure variations are important for high-quality steel productions. In this study, the multi-frequency electromagnetic technology is used to effectively characterize changes of steel microstructures. Steel samples with individual micro- components are obtained using different heat treatments and are measured using a self-designed multi-frequency electromagnetic system. Micro- and Macro- FE models are developed to discuss electromagnetic responses on steel microstructures with different phases, grain size and grain boundaries. The relative permeability of different steel microstructures are calculated and discussed. Results show that the low frequency inductance will increase with the increase of ferrite grain size and ferrite fraction. The relative permeability of single ferrite grain boundary is determined to be 165 and the orientation of grain boundary can influence the relative permeability of steel microstructures.

Nanoscale Imaging and Measurements of Grain Boundary Thermal Resistance in Ceramics with Scanning Thermal Wave Microscopy.

Material thermal conductivity is a key factor in various applications, from thermal management to energy harvesting. With microstructure engineering being a widely used method for customizing material properties, including thermal properties, understanding and controlling the role of extended phonon-scattering defects, like grain boundaries, is crucial for efficient material design. However, systematic studies are still lacking primarily due to limited tools. In this study, we demonstrate an approach for measuring grain boundary thermal resistance by probing the propagation of thermal waves across grain boundaries with a temperature-sensitive scanning probe. The method, implemented with a spatial resolution of about 100 nm on finely grained Nb-substituted SrTiO3 ceramics, achieves a detectability of about 2 × 10-8 K m2 W-1, suitable for chalcogenide-based thermoelectrics. The measurements indicated that the thermal resistance of the majority of grain boundaries in the STiO3 ceramics is below this value. While there are challenges in improving sensitivity, considering spatial resolution and the amount of material involved in the detection, the sensitivity of the scanning probe method is comparable to that of optical thermoreflectance techniques, and the method opens up an avenue to characterize thermal resistance at the level of single grain boundaries and domain walls in a spectrum of microstructured materials.

Mitigating Temporal Fragility in the XY Surface Code

An important outstanding challenge that must be overcome in order to fully utilize the XY surface code for correcting biased Pauli noise is the phenomenon of fragile temporal boundaries that arises during the standard logical state-preparation and measurement protocols. To address this challenge we propose a new logical state-preparation protocol based on locally entangling qubits into small Greenberger-Horne-Zeilinger-like states prior to making the stabilizer measurements that place them in the XY-code state. We prove that in this new procedure O(n) high-rate errors along a single lattice boundary can cause a logical failure, leading to an almost quadratic reduction in the number of fault configurations compared to the standard state-preparation approach. Moreover, the code becomes equivalent to a repetition code for high-rate errors, guaranteeing a 50% code-capacity threshold during state preparation for infinitely biased noise. With a simple matching decoder we confirm that our preparation protocol outperforms the standard protocol in terms of both threshold and logical error rate in the fault-tolerant regime where measurements are unreliable and at experimentally realistic biases. We also discuss how our state-preparation protocol can be inverted for similar fragile-boundary-mitigated logical-state measurement. Published by the American Physical Society 2024

Characterization of the complete chloroplast genome of Rhodiola sachalinensis and comparative analysis with its congeneric plants.

Rhodiola, belonging to the Crassulaceae family, is a perennial herbaceous plant genus. There are about 90 Rhodiola species worldwide, some of which have been reported to have medicinal properties. Rhodiola sachalinensis is a perennial medicinal herb within this genus and, in the present study, its chloroplast genome was sequenced, assembled, annotated and compared with 24 other Rhodiola species. The results obtained show that the chloroplast genome of R. sachalinensis is 151 595 bp long and has a CG content of 37.7%. The inverted repeats (IR) region of the Rhodiola chloroplast genome is the most conserved region, with the main differences being observed in the ycf1 and ndhF genes at the IRb-small single copy boundary, and rps19 and trnH genes at the IRa-large single copy boundary. Phylogenetic analysis showed that Rhodiola species form two major clades, and species with recorded medicinal properties, clustered together in one branch except for R. dumulosa. Within the genus, R. sachalinensis is most closely related to Rhodiola rosea, although comparative analyses showed that only R. sachalinensis and Rhodiola subopposita contained the psbZ gene, which encodes a highly conserved protein subunit of the Photosystem II core complex. Overall, the present study contributes to the understanding of the chloroplast genome of Rhodiola species, and provides a theoretical basis for the study of their genetic diversity and possible use as medicinal plants.

Neural mechanism underlying preview effects and masked priming effects in visual word processing.

Two classic experimental paradigms - masked repetition priming and the boundary paradigm - have played a pivotal role in understanding the process of visual word recognition. Traditionally, these paradigms have been employed by different communities of researchers, with their own long-standing research traditions. Nevertheless, a review of the literature suggests that the brain-electric correlates of word processing established with both paradigms may show interesting similarities, in particular with regard to the location, timing, and direction of N1 and N250 effects. However, as of yet, no direct comparison has been undertaken between the two paradigms. In the current study, we used combined eye-tracking/EEG to perform such a within-subject comparison using the same materials (single Chinese characters) as stimuli. To facilitate direct comparisons, we used a simplified version of the boundary paradigm - the single word boundary paradigm. Our results show the typical early repetition effects of N1 and N250 for both paradigms. However, repetition effects in N250 (i.e., a reduced negativity following identical-word primes/previews as compared to different-word primes/previews) were larger with the single word boundary paradigm than with masked priming. For N1 effects, repetition effects were similar across the two paradigms, showing a larger N1 after repetitions as compared to alternations. Therefore, the results indicate that at the neural level, a briefly presented and masked foveal prime produces qualitatively similar facilitatory effects on visual word recognition as a parafoveal preview before a single saccade, although such effects appear to be stronger in the latter case.

Phase-field simulation study on dendritic growth behavior during bilateral directional solidification

The directional solidification technique can uniform the crystal growth direction within the material, but does not remove the lateral side branches of the axial main arm during the growth process. The influence of such lateral side branches existing in the directionally solidified dendritic organisation on the mechanical properties of the material cannot be neglected. In this paper, based on the Kim-Kim-Suzuki (KKS) phase-field model, the competitive behaviour of lateral secondary dendrites between the two main arms under different boundary conditions and non-synchronous growth conditions is investigated for Fe-0.5 %C alloys. In addition, the diffusion and enrichment rules of solutes are analysed by the distribution of solutes. The results show that the molten pool is spherical without external force, and the size distribution of the molten pool is as follows: dendrite tip collision zone > dendrite root > dendrite wall, and the solute segregation rule is the same; The spacing of the main arms has little effect on the concentration values between the dendrites, and the solutes are very symmetrically over the entire computational region; The dendrite tip interface concentration during the stable phase of dendrite growth is 0.89 %. Without considering the initial liquid-phase concentration, the concentration in the collision zone at the dendrite tip is approximately twice the concentration at the tip of the dendrite in the stable period, which is 1.28 %, when the bilateral dendrites are encountered. Dendrites always collide preferentially on the centreline of the included angle under non-parallel conditions, and solute-enriched zones also occur on the centreline of the included angle; During the curved surface bilaterally directional solidification process, when the left and right sides have the same shape of surfaces, the solute enrichment at the end of solidification is on the centreline. For the case of a single planar boundary, the solute-enriched region is influenced by the curved surface and is similar to the initial curved surface profile.

A Taxonomy of Upper‐Mantle Stratification in the US

AbstractThe investigation of upper mantle structure beneath the US has revealed a growing diversity of discontinuities within, across, and underneath the sub‐continental lithosphere. As the complexity and variability of these detected discontinuities increase—for example, velocity increase/decrease, number of layers and depth—it is hard to judge which constraints are robust and which explanatory models generalize to the largest set of constraints. Much work has been done to image discontinuities of interest using S‐waves that convert to P‐waves (or top‐side reflected SS waves). A higher resolution method using P‐to‐S scattered waves is preferred but often obscured by multiply reflected waves trapped in a shallower layer, limiting the visibility of deeper boundaries. Here, we address the interference problem and re‐evaluate upper mantle stratification using filtered P‐to‐S receiver functions (Ps‐RFs) interpreted using unsupervised machine‐learning. Robust insight into upper mantle layering is facilitated with CRISP‐RF: Clean Receiver‐Function Imaging using Sparse Radon Filters. Subsequent sequencing and clustering organizes the polarity‐filtered Ps‐RFs into distinct depth‐based clusters. We find three types of upper mantle stratification beneath the old and stable continental US: (a) intra‐lithosphere discontinuities (paired or single boundary), (b) transitional discontinuities (single boundary or with a top layer), and (c) sub‐lithosphere discontinuities. Our findings contribute a more nuanced understanding of mantle discontinuities, offering new perspectives on the nature of upper mantle layering beneath continents.

DNS vs. LES: Turbulent flow in square duct with heated foil boundary

Turbulent heat transfer in a square duct, where a finite section of a single duct boundary is heated with an infinitely thin foil, was analyzed with LES and DNS approaches. Both computations were performed with OpenFOAM code with passive scalar approximation, using second order accurate schemes. Results are obtained for the key velocity and temperature statistics in the duct, with an emphasis on the temperature profiles and temperature fluctuations at the foil boundary, which appear due to the imposed constant heat flux boundary condition at the foil. Comparison of DNS and standard LES-WALE model show 20% higher foil temperatures and temperature fluctuations in LES results. These differences are explained with detailed analysis of the LES-WALE model near-wall behavior. It has been demonstrated that LES-WALE yields highly accurate results only when employed with a finely resolved mesh. However, the computational costs associated with such refinement may not be necessarily justified especially with respect to DNS.

Shape, velocity, and exact controllability for the wave equation on a graph with cycle

Exact controllability is proved on a graph with cycle. The controls can be a mix of controls applied at the boundary and interior vertices. The method of proof first applies a dynamical argument to prove shape controllability and velocity controllability, thereby solving their associated moment problems. This enables one to solve the moment problem associated with exact controllability. In the case of a single control, either boundary or interior, it is shown that exact controllability fails.

Obstacle Problems with Double Boundary Condition for Least Gradient Functions in Metric Measure Spaces

AbstractIn the setting of a metric space equipped with a doubling measure supporting a (1, 1)-Poincaré inequality, we study the problem of minimizing the BV-energy in a bounded domain $$\Omega $$ Ω of functions bounded between two obstacle functions inside $$\Omega $$ Ω , and whose trace lies between two prescribed functions on the boundary. If the class of candidate functions is nonempty, we show that solutions exist for continuous obstacles and continuous boundary data when $$\Omega $$ Ω is a uniform domain whose boundary is of positive mean curvature in the sense of Lahti, Malý, Shanmugalingam, and Speight (2019). While such solutions are not unique in general, we show the existence of unique minimal solutions. Since candidate functions need not agree outside of the domain, standard compactness arguments fail to provide existence of weak solutions as they are defined for the problem with single boundary condition. To overcome this, we introduce a class of $$ \varepsilon $$ ε -weak solutions as an intermediate step. Our existence results generalize those of Ziemer and Zumbrun (1999), who studied this problem in the Euclidean setting with a single obstacle and single boundary condition.

Eco-emotions as the planetary boundaries: framing human emotional and planetary health in the global environmental crisis

BackgroundAffective processes play an important role in physical and mental health and in adaptation responses to the global environmental crisis. Eco-emotions—emotions that are substantially associated with the environment and anthropogenic changes happening within it—are complex and culturally varied. Despite the disproportionate impact of the global environmental crisis on low-income and middle-income countries, most psychological research to date has been conducted in high-income countries and has focused on climate change and negative climate emotions (eg, climate anxiety). The absence of diverse, globally representative evidence about emotions associated with the global environmental crisis beyond climate change hinders evidence-based action on psychological adaptation and the development of contextually and culturally appropriate coping strategies toward the wider range of negative anthropogenic effects. To account for this wider range of anthropogenic effects, we previously introduced an eco-emotions framework built on the planetary boundaries concept. We aimed to apply this framework to the current research on eco-emotional responses to identify remaining gaps that hinder evidence-based action. MethodsWe conducted a literature review of peer-reviewed studies assessing core affect (ie, emotional valence and arousal) and emotions with emphasis on study populations from low-income and middle-income countries and on the eight non-climate change planetary boundaries (biodiversity loss, freshwater use, ocean acidification, chemical pollution, air pollution, land system change, ozone depletion, and nitrogen and phosphorus perturbation). We searched Web of Science from database inception to Oct 31, 2023, for observational empirical studies of adults, using planetary boundary-specific (eg, freshwater use) or wider, newer, or overarching emotional concept (eg, solastalgia, environmental change) search terms. FindingsIn contrast to previous climate emotions work, our preliminary results of 135 peer reviewed studies identified a significant body of literature beyond climate change concerning emotional responses to the planetary boundaries of biodiversity loss, freshwater scarcity, and chemical pollution as well as emerging evidence of emotional responses to the other five planetary boundaries. InterpretationWe found that the spectrum of eco-emotional responses ranged from being specific to a single planetary boundary to encompassing all planetary boundaries. Our findings underscore the importance of and urgent need for more holistic and diverse psychological intervention strategies targeting the wider range of anthropogenic effects during the rapidly intensifying global environmental crisis. FundingEmmett Interdisciplinary Program in Environment and Resources; McGee and Levorsen Research Grant Program; and Center on Philanthropy and Civil Society at Stanford University.

Solutions for Poissonian stopping problems of linear diffusions via extremal processes

We develop a general yet simple technique for solving Poissonian timing problems of linear diffusions by relying on the close connection of the extremal processes and the first passage times of the underlying diffusion. We provide a closed-form representation of the expected value gained by employing an ordinary first passage time-based stopping strategy. This approach simplifies the determination of the optimal policy, transforming it into an analysis of ordinary first-order optimality conditions. We relate our findings to various existing approaches for solving stopping problems of linear diffusions and express the optimality conditions in a single boundary setting in a form familiar from optimal stopping of Lévy-processes.

Wilson loops and wormholes

We analyse the properties of Wilson loop observables for holographic gauge theories, when the dual bulk geometries have a single and/or multiple boundaries (Euclidean spacetime wormholes). Such observables lead to a generalisation and refinement of the characterisation in [1] based on the compressibility of cycles and the pinching limit of higher genus Riemann surfaces, since they carry information about the dynamics and phase structure of the dual gauge theory of an arbitrary dimensionality. Finally, we describe how backreacting correlated observables such as Wilson loops can lead to wormhole saddles in the dual gravitational path integral, by taking advantage of a representation theoretic entanglement structure proposed in [13, 15].

Spontaneous Alignment of Myotubes Through Myogenic Progenitor Cell Migration.

In large-volume muscle injuries, widespread damage to muscle fibers and the surrounding connective tissue prevents myogenic progenitor cells (MPCs) from initiating repair. There is a clinical need to rapidly fabricate large muscle tissue constructs for integration at the site of large volume muscle injuries. Most strategies for myotube alignment require microfabricated structures or prolonged orientation times. We utilize the MPC's natural propensity to close gaps across an injury site to guide alignment on collagen I. When MPCs are exposed to an open boundary free of cells, they migrate unidirectionally into the cell-free region and align perpendicular to the original boundary direction. We study the utility of this phenomenon with biotin-streptavidin adhesion to position the cells on the substrate, and then demonstrate the robustness of this strategy with unmodified cells, creating a promising tool for MPC patterning without interrupting their natural function. We preposition MPCs in straight-line patterns separated with small gaps. This temporary positioning initiates the migratory nature of the MPCs to align and form myotubes across the gaps, similar to how they migrate and align with a single open boundary. There is a directional component to the MPC migration perpendicular (90°) to the original biotin-streptavidin surface patterns. The expression of myosin heavy chain, the motor protein of muscle thick filaments, is confirmed through immunocytochemistry in myotubes generated from MPCs in our patterning process, acting as a marker of skeletal muscle differentiation. The rapid and highly specific binding of biotin-streptavidin allows for quick formation of temporary patterns, with MPC alignment based on natural regenerative behavior rather than complex fabrication techniques.