Boundary Spacing Research Articles

Empirical Study on the Boundary Space Form of Residential Blocks Oriented Toward Low-Carbon Travel

As one of the three major carbon sources in cities, urban mobility has posed severe challenges to the social environment. Promoting low-carbon travel for residents is an important measure for building a low-carbon city and mitigating climate change. However, to date, previous research on residents’ low-carbon travel has been more oriented toward urban planning, while quantitative research on the influence of the boundary space form of residential blocks on residents’ travel modes, which takes residential blocks as the research objects at the meso- and micro-level, is relatively rare. Residential blocks in China, which were built in the late 1990s, mostly have a large and gated spatial form. Individual residential blocks are often gated by fences, commercial buildings, and other forms of interfaces, forming an independent residential group. Long and closed boundary forms will have a certain impact on residents’ choice of low-carbon travel modes, such as walking, riding bikes, and so on. Taking Nanjing as an example, this paper explores the essential factors that impact residents’ travel behaviors from the perspective of the boundary space of residential blocks, combining the socio-economic attributes of residents, land use, and transit facilities, and there are four dimensions to the study, including the boundary block scale, types of boundary interface, density and distribution of accesses, and the slow-travel environment, proposing recommended values of the relevant indicators in a targeted manner. This paper selects 21 residential blocks in the main districts in Nanjing, conducting a related survey on the residents’ socio-economic attributes and travel characteristics, boundary space form, land use, and transit facilities. The data obtained from the survey are analyzed by correlation analysis and multiple logistic regression analysis, so as to screen out the key variables of the boundary space forms of the blocks that affect residents’ low-carbon travel. Meanwhile, on the basis of the appropriate share of low-carbon travel, the unary linear regression model is used to propose ideal recommended values of the key variables of the boundary space forms of the residential blocks. For instance, the block boundary density is recommended to be above 34.38 km/km², the permeability coefficient of the block interface should be above 0.43, the commercial interface ratio should be above 18.16 km/km², the density of accesses of the blocks is recommended to be above 246.71 km/km², and the cross-sectional ratio of the slow-travel roads should be above 0.5.

Heterogeneous microstructure and enhanced mechanical properties in annealed multilayered IF steel

The microstructure and mechanical properties have been studied in interstitial free (IF) steel samples consisting of compression-bonded alternating layers of initially either cold-rolled (CR) or recrystallized (AR) material. After compression bonding followed by cold compression, the microstructure of the initial CR layers is characterized by a fine boundary spacing, while the boundary spacing in the initial AR layers is greater. Annealing of this compression-bonded sample is carried out at 600 °C to achieve a highly heterogeneous microstructure. During the early stages of annealing, coarsening is more pronounced in the CR layers leading to a more rapid reduction in the stored energy than in the AR layers. Further annealing results in recrystallization taking place preferentially in the AR layers with the consequence that the slowly recrystallizing CR layers are considerably harder than the AR layers. Tensile testing demonstrates that in this multilayered microstructure combinations of high strength and comparatively high ductility are achieved in the samples annealed at 600 °C for either 1 h or 1.5 h, when the microstructure is strongly heterogeneous with a large difference in the fraction of recrystallized material between the initial CR and AR layers. Such samples with alternating hard and soft layers are found to have a better combination of strength and ductility than other IF-steel samples with a more homogeneous microstructure. The enhanced strength in the annealed multilayered compression-bonded samples can be attributed to the influence of mechanical constraints between the layers.

Influences of Boundary Space Amelioration on Residents' Key Perceptions in Communities

Boundary space amelioration (BSA) aims to eliminate barriers between two sites and activate the grey residual space in-between. School campus in Taiwan is often surrounded by walls, which blocks its connection to communities and often creates security concerns. School campus has become the most popular target for BSA, which tries to turn it into a functional and aesthetic space. This study intends to explore the influences of campus BSA within a community, especially its relationships with neighborhood safety, perceived change and place attachment. The result shows that the improvement of boundary environment has a significant influence on all three perceptions.

Performative Actions As a Method of Participation Boundary Spaces in Five Beijing Residential Neighbourhoods

Performative Actions As a Method of Participation Boundary Spaces in Five Beijing Residential Neighbourhoods

Classification Method of Teaching Resources Based on Improved KNN Algorithm

In order to effectively utilize the network teaching resources, a teaching resource classification method based on the improved KNN (K-Nearest Neighbor) algorithm was proposed. Taking the text class primary and secondary school teaching resources as the research object, combined with the domain characteristics, the KNN algorithm was improved. By measuring the sample space density, the text of the high-density area was found. Different clipping methods were proposed for both intra-class and inter-class regions. The problem of cropping in the space of multiple class boundaries was considered. Results showed that the method ensured uniform distribution of samples and reduced the time of classification. Therefore, under the Weka platform, the improved KNN algorithm is effective.

Large Dietary Niche Overlap of Sympatric Open-space Foraging Bats Revealed by Carbon and Nitrogen Stable Isotopes

Sympatric bats engage in various strategies for dietary niche partitioning such as different microhabitat use; however, no previous study has yet looked at potential dietary niche partitioning in mammals foraging in a space void of any physical structure. Here, we used stable isotope ratios of carbon and nitrogen to investigate if three insectivorous bats of central Thailand, Chaerephon plicatus, Taphozous melanopogon and T. theobaldi, partition food resources when foraging in the open space of the lower boundaries of the troposphere. We quantified the isotopic dietary niches of these species and compared niche dimensions within the guild of openspace foraging bats and between this guild and the edge-foraging bat Hipposideros larvatus. Our results showed that stable isotope ratios of bats differed between wet and dry seasons. Consistently, open-space foraging bat species shared a similar isotopic composition in both seasons, which contrasted that of the edge-space foraging H. larvatus. Isotopic niche dimensions of open-space foraging bats were smaller than those of the edge-space foraging bat. Based on isotopic data, we inferred that open-space foraging bats foraged mostly on dipterans which may fly or drift to higher altitudes where these bats hunt. In contrast, H. larvatus included mostly beetles from C4food webs in their diet, highlighting that this species is an important predator of pest insects of C4crops, namely cane sugar and corn. Our study emphasizes that the unstructured aerosphere in which open-space foraging bats hunt insects may promote a large overlap in the diet of these species. We conclude that mechanisms other than trophic niche differentiation, such as the motion capacity of bat species, both in terms of covered distances and accessed altitudes may facilitate the coexistence of high-altitude foraging bats.

Representation and uniqueness for boundary value elliptic problems via first order systems

Given any elliptic system with t -independent coefficients in the upper-half space, we obtain representation and trace for the conormal gradient of solutions in the natural classes for the boundary value problems of Dirichlet and Neumann types with area integral control or non-tangential maximal control. The trace spaces are obtained in a natural range of boundary spaces which is parametrized by properties of some Hardy spaces. This implies a complete picture of uniqueness vs solvability and well-posedness.

La frontera entre la antropología y la literatura en Juan Pérez Jolote

En este artículo se analiza la obra paradigmática Juan Pérez Jolote (1948), del antropólogo Ricardo Pozas, como un espacio fronterizo del diálogo entre la antropología y la literatura en el México posrevolucionario. Se conceptualiza el texto de Pozas como una "frontera" semiótica según la terminología desarrollada por Yuri Lotman. Además, se plantea que debido a su posición como frontera no es posible entender Juan Pérez Jolote a través de la disyuntiva "antropología o ficción".

Materializing the blue economy: tuna fisheries and the theory of access in the Western Indian Ocean

<p>Many African countries are progressively embracing the blue economy. African islands of the western Indian Ocean, however, have been involved in it for more than twenty years through the exploitation of their 'blue gold': tuna. In this article, we use Ribot and Peluso's (2003) "theory of access" to map the different ways actors access tuna under diverse socio-economic contexts and how power relations are created through different mechanisms of access. We show that rights-based mechanisms such as fishing access agreements are highly questionable for their fairness and sustainability but bring benefits such as funding for fisheries-related infrastructures and projects. We also show that access to the resource is dependent on knowledge held by fishers, on technological advances as well as on diverse labor relations. These mechanisms significantly impact the quantity of fish that can be accessed by artisanal versus industrial market sectors, and generate narratives of unequal access to tuna. Furthermore, we take into consideration the materiality of tuna as a highly mobile resource in a space of fluid boundaries, to show how the fish can be an actant in shaping access but also how fishing practices can produce new materialities. Based on the above evidence, we propose an enhancement of the theory of access to consider the role of materiality of the resources and the sea. We conclude that to ensure that tuna fisheries continue to contribute to the blue economy of African islands, stakeholders need to balance between the diverse benefits produced by the fisheries and the uneven power relations that can arise, and to integrate the impact of a material sea and fish in this reflection. </p><p><strong>Keywords</strong>: fishers, knowledge, materiality, power relations, spatiality of the sea, technology, Madagascar, Mauritius, Seychelles</p>

From the Editor

From the Editor Julie Pfeiffer (bio) In an Anansi story retold in Matthew Lewis's 1834 Journal of a West India Proprietor, the obedient heroine is sent out to gather eggs and is warned to ignore the talking eggs that clamor for her attention in favor of those that are silent. Despite the fact that the talking eggs are plentiful and attractive, the girl collects "three little dirty-looking eggs, that had not a word to say for themselves" (257). This complex tale, which is usefully analyzed by Courtney Weikle-Mills in her essay in this volume, seems particularly apt at a cultural moment in which loud voices demand our attention on every side and we may find ourselves drowning in what José Esteban Muñoz calls "the quagmire of the present" (1). Just as the girl in the hen house is rewarded for her obedient attention to that which is hidden, these essays help us to see softer, less visible perspectives and offer strategies for new ways of seeing ourselves and others. Volume 47 of Children's Literature opens with a forum on Latinx Young Adult literature, coedited by Marilisa Jiménez García. In her introduction to the forum, "The Lens of Latinx Literature," Jiménez García calls for a critical discourse that pairs attention to Latinx YA novels and picture books with the acknowledgment that the long history of Latinx criticism gives us a framework that helps us see "how children's and young adult literature behaves as an aesthetic and political medium." In the two forum essays that follow, Sonia Alejandra Rodríguez ("Conocimiento Narratives: Creative Acts and Healing in Latinx Children's and Young Adult Literature") and Angel Daniel Matos ("A Narrative of a Future Past: Historical Authenticity, Ethics, and Queer Latinx Futurity in Aristotle and Dante Discover the Secrets of the Universe") provide examples of how the lens of Latinx criticism can help us enter a fluid space of boundary crossing between trauma and creativity (Rodríguez) and between historical realities and fiction (Matos). Jiménez García writes, "We forget that although Indigenous and people of color writers and scholars have been marginalized in literary and cultural history by conquest and colonization, the contributions of these communities are not marginal"; in the work of Latinx scholars we find strategies that help all of us negotiate the space of what Gloria E. Anzaldúa calls nepantla, "the overlapping space between different perceptions and belief systems" (11). [End Page vii] This overlapping space is one way of creating a bridge that can lead us out of quagmires. In "now let us shift … the path of conocimiento … inner work, public acts," Anzaldúa calls for a creative revolution in our self-awareness, bridge-building, and advocacy. Anzaldúa imagines this shift as an awareness of our own epistemologies and the ways our "constructions violate other people's ways of knowing and living" (44). The essays in this volume share her commitment to the flexible space of kinship, the work of acknowledging our own violations, and the power of the imagination to reimagine present and future possibilities. With "The Obscure Histories of Goosee Shoo-shoo and Black Cinderella: Seeking Afro-Caribbean Children's Literature in the Nineteenth Century," Courtney Weikle-Mills offers us a reframing of children's literature of Afro-Caribbean enslaved peoples. Weikle-Mills calls on us to approach non–Anglo-American sources flexibly, "not seeing them as irrelevant to the field because they do not have a wholly child audience, connection to a genealogy of printed European children's literature, and relationship to an Anglo-American concept of childhood innocence." The "two-shoe" method of this essay helps us see the double narrative in Afro-Caribbean stories that use "childhood, especially girlhood, as a site for resistance." Dawn Sardella-Ayres argues for the transgressive potential of The Little Colonel and its heroine, Lloyd, in "Rewriting and Re-Whiting The Little Colonel: Racial Anxieties, Tomboyism, and Lloyd Sherman." While Lloyd appears to embody the privilege of the "Beautiful Child," her transgressive movement between identity categories unsettles white aristocratic privilege. Unlike the girl protagonist who must be cured of her nonwhiteness in order to save...

Grain boundary electrical characteristics for rutile TiO<sub>2</sub> under pressure

In this paper, the grain and grain boundary characteristics of pure rutile TiO<sub>2</sub> under pressure are investigated by electrochemical impedance spectroscopy equipped with diamond anvil cell (DAC). Only one semi-circle can be detected under each pressure in a range of 1.4–11.5 GPa. With the pressure increasing, the shape of semi-circle is unchanged, while the size of semi-circle gradually decreases, which can be attributed to the decrease of bulk resistance due to the reduction of band gap under pressure. The absence of grain boundary characteristic in the impedance spectra signifying that Schottky barrier is not present at the grain boundaries. With further increasing pressure, an interesting phenomenon can be observed above 12.7 GPa. The shape of semi-circle is distorted, and exhibits two overlapping semi-circles. The first semi-circle (high frequency) originates from the contribution of bulk, and the second one (low frequency) can be ascribed to the effect of grain boundary. The occurrence of grain boundary semicircle indicates that the aggregation of space charges at the grain boundary. In this case, the phase transformation from rutile to baddeleyite structure occurs, the electric transport mechanism is changed, and new lattice defects are formed. Also, two discontinuous points (11.5 and 15.4 GPa) can be detected in the resistance curve. The remarkable change of resistance occurs at 12.7 GPa which is corresponding to the phase transition from rutile to baddeleyite phase. The occurrence of phase transition leads the new interfacial energy to occur, the total energy of system to increase, and the movement of carriers to impede. Thus, the resistance increases significantly, and the maximum value occurs at 15 GPa. Further analysis indicates that the space charge potential is modified with pressure increasing, implying that the electrical transport properties of TiO<sub>2</sub> are related closely to phase transition. With the pressure increasing from 12.7 to 25.2 GPa, the irregular change of space charge potential can be attributed to the rutile and baddeleyite phase coexisting. When the pressure is higher than 25.2 GPa, the space charge potential is a constant (about 30 mV). According to the investigations, the TiO<sub>2</sub> grain boundary space charge potential under pressure is mainly contributed from two parts: the electrostatic interaction and the elastic interaction.

Molecular dynamics study of copper nanosprings with/without twin boundary structures

Nanosprings have drawn continuous attention due to their superior elongation and potential applications in stretchable devices. Based on molecular dynamics (MD) simulations, the deformation mechanism of Cu nanosprings with/without twin boundary (TB) structures is investigated in this work. It is found that dislocation-driven deformation mechanism of nanosprings mainly depends on their geometry parameters. During the plastic process, severe distortion caused by local dislocation emission is frequently observed, especially for nanosprings with large wire diameters. Small twin boundary spacings (TBSs) can effectively improve the mechanical properties of nanosprings through restricting dislocation emission and TB migration. In addition, the calculated spring constant reveals that the stiffness of nanosprings with larger wire diameters, smaller helix pitches or smaller TBSs will become larger. It is also worth mentioning that the classical theory is still valid in nanosprings with TB structures. These findings open a new avenue to design novel nanosprings for nanodevices.

Conceptualizing a Sustainable Food System in an Automated World: Toward a “Eudaimonian” Future

The industrialized world has entered a new era of widespread automation, and although this may create long-term gains in economic productivity and wealth accumulation, many professions are expected to disappear during the ensuing shift, leading to potentially significant disruptions in labor markets and associated socioeconomic difficulties. Food production, like many other industrial sectors, has also undergone a century of mechanization, having moved toward increasingly large-scale monoculture production—especially in developed economies—with higher yields but detrimental environmental impacts on a global scale. Certain characteristics of the food sector and its products cast doubts on whether future automation will influence it in the same ways as in other sectors. We conceptualize a model of future food production within the socioeconomic conditions created by widespread automation. We ideate that despite immediate shocks to the economy, in the long run higher productivity can free up human activity to be channeled toward more interactive, skill-intensive food production systems, where communal efforts can reduce industrial reliance, diversify farming, and reconnect people to the biosphere—a realization of human well-being that resembles the classical philosophical ideal of Eudaimonia. We explore food production concepts, such as communal gardens and polyculture, and the economic conditions and institutions needed to underwrite them [e.g., a universal basic income (UBI)]. However, arguments can be raised as to why social-ecological systems would benefit from more labor-intensive food production. In this paper we: (1) discuss the current state of the food system and the need to reform it in light of its environmental and social impacts; (2) present automation as a lever that could move society toward more sustainable food production; (3) highlight the beneficial attributes of a Eudaimonian model; and (4) discuss the potential challenges to its implementation. Our purpose is to highlight a possible outcome that future research will need to refine and expand based on evidence and successful case studies. The ultimate aim is to promote a food system that can provide food security while staying within the safe operating space of planetary boundaries, produce more nutritious diets, enhance social capital, and reconnect communities with the biosphere.

Density of convex billiards with rational caustics

We show that in the space of all convex billiard boundaries, the set of boundaries with rational caustics is dense. More precisely, the set of billiard boundaries with caustics of rotation number 1/q is polynomially sense in the smooth case, and exponentially dense in the analytic case.

Effects of Heterogeneous Microstructures on the Strain Hardening Behaviors of Ferrite-Martensite Dual Phase Steel

The complex strain hardening behaviors of dual phase (DP) steel are subjected to the heterogeneous microstructures. The current work aims to predict the strain hardening behaviors of ferrite-martensite DP steel, focusing on the effects of heterogeneous microstructure on mechanical properties. The flow stress of material was calculated based on the dislocation-based work-hardening model with considering the multi-boundaries hardening. The ferrite-martensite phase boundary percent and grain shape factor were selected as the heterogeneous feature parameters, which were introduced into the new proposed model. The theoretical calculated stress-strain responses were verified with experimental results using the tensile test. The model with the boundary strengthening consideration has more accurate results. The parameter effects of ferrite-ferrite boundary (FFB) spacing, ferrite-martensite boundary (FMB) percent, and grain shape factor on the flow stress-strain curve were researched.

Design Method Using Statistical Models for Miniature Left Ventricular Assist Device Hydraulics.

Left ventricular assist devices (LVADs) are increasingly used to treat heart failure patients. These devices' impeller blades and diffuser vanes must be designed for hydraulic performance and hemocompatibility. The traditional design method, applying mean-line theory, is not applicable to the design of small-scale pumps such as miniature LVADs. Furthermore, iterative experimental testing to determine how each geometric variable affects hydraulic performance is time and labor intensive. In this study, we tested a design method wherein empirical hydraulic results are used to establish a statistical model to predict pump hydraulic performance. This method was used to design an intra-atrial blood pump. Five geometric variables were chosen, and each was assigned two values to define the variable space. The experimental results were then analyzed with both correlation analysis and linear regression modeling. To validate the linear regression models, 2 test pumps were designed: mean value of each geometric variable within the boundaries, and random value of each geometric variable within the boundaries. The statistical model accurately predicted the hydraulic performance of both pump designs within the boundary space. This method could be expanded to include more geometric variables and broader boundary conditions, thus accelerating the design process for miniature LVADs.

Evaluation of Model Concepts to Describe Water Transport in Shallow Subsurface Soil and Across the Soil\u2013Air Interface

Soil water evaporation plays a critical role in mass and energy exchanges across the land–atmosphere interface. Although much is known about this process, there is no agreement on the best modeling approaches to determine soil water evaporation due to the complexity of the numerical modeling scenarios and lack of experimental data available to validate such models. Existing studies show numerical and experimental discrepancies in the evaporation behavior and soil water distribution in soils at various scales, driving us to revisit the key process representation in subsurface soil. Therefore, the goal of this work is to test different mathematical formulations used to estimate evaporation from bare soils to critically evaluate the model formulations, assumptions and surface boundary conditions. This comparison required the development of three numerical models at the REV scale that vary in their complexity in characterizing water flow and evaporation, using the same modeling platform. The performance of the models was evaluated by comparing with experimental data generated from a soil tank/boundary layer wind tunnel experimental apparatus equipped with a sensor network to continuously monitor water–temperature–humidity variables. A series of experiments were performed in which the soil tank was packed with different soil types. Results demonstrate that the approaches vary in their ability to capture different stages of evaporation and no one approach can be deemed most appropriate for every scenario. When a proper top boundary condition and space discretization are defined, the Richards equation-based models (Richards model and Richards vapor model) can generally capture the evaporation behaviors across the entire range of soil saturations, comparing well with the experimental data. The simulation results of the non-equilibrium two-component two-phase model which considers vapor transport as an independent process generally agree well with the observations in terms of evaporation behavior and soil water dynamics. Certain differences in simulation results can be observed between equilibrium and non-equilibrium approaches. Comparisons of the models and the boundary layer formulations highlight the need to revisit key assumptions that influence evaporation behavior, highlighting the need to further understand water and vapor transport processes in soil to improve model accuracy.

Deformation mechanisms in nanotwinned γ-TiAl by molecular dynamics simulation

ABSTRACTIn this work, the plastic deformation mechanisms and fracture toughness of nanotwinned γ-TiAl with different twin boundary (TB) spacing are investigated by using molecular dynamics simulation. The simulation results reveal that there are pronounced shifts in the mechanical behaviour of nanotwinned γ-TiAl when the TB spacing is 3.50, 4.20 and 4.90 nm. In addition, the variation of the dislocation density with strain at these three TB spacing illustrates that a smaller TB spacing induces a higher dislocation density. Different TB spacing has an influence on the dislocation behaviour. The dislocation pile-up, dislocation–dislocation, dislocation–twin and twin–twin reactions, hierarchical twins including their generation and density, step formation, dislocation emission from steps and TB migration are the main plastic deformation mechanisms. The results also show that TB migration, twinning formation and interaction of crack and TB dominate the deformation mechanism of nanotwinned γ-TiAl with crack. The generation of hierarchical twins, lower distance between crack surface plane and twin plane, dislocation–twin, twin–twin interaction and crack deflection increase the fracture toughness of nanotwinned γ-TiAl.

Extended Hodge theory for fibred cusp manifolds

For a particular class of pseudo manifolds, we show that the intersection cohomology groups for any perversity may be naturally represented by extended weighted [Formula: see text] harmonic forms for a complete metric on the regular stratum with respect to some weight determined by the perversity. Extended weighted [Formula: see text] harmonic forms are harmonic forms that are almost in the given weighted [Formula: see text] space for the metric in question, but not quite. This result is akin to the representation of absolute and relative cohomology groups for a manifold with boundary by extended harmonic forms on the associated manifold with cylindrical ends. In analogy with that setting, in the unweighted [Formula: see text] case, the boundary values of the extended harmonic forms define a Lagrangian splitting of the boundary space in the long exact sequence relating upper and lower middle perversity intersection cohomology groups.

Serious games as a catalyst for boundary crossing, collaboration and knowledge co-creation in a watershed governance context

Novel methods for enhancing collaboration and interactions are required to ensure that stakeholders and governments are able to develop a shared vision that supports sustainable watershed governance. Particular attention must be placed on integrating stakeholders who would otherwise have limited decision-making power. By crossing professional, ideological and jurisdictional boundaries, stakeholders' perspectives are more likely to change than when staying within those boundaries. This process, known as boundary crossing, requires boundary objects; either artifacts, people, or institutions that play a bridging role between different boundary spaces. For this study, serious games powered by scientific models are identified as potentially effective boundary objects. A serious game simulation called Aqua Republica was used to organize game simulation events allowing stakeholders to connect in an in-person, informal and novel setting. This exploratory research aims to study the role and impact of serious games as boundary objects to enhancing collaboration and knowledge co-creation. The following research questions are addressed: (1) Do interactions increase over the course of a game simulation event? (2) Does the quality of interactions change over the course of a game simulation event? (3) Are the quantity and quality of interactions affected by pre-existing relationships? And if so, how? (4) How does the relationship between participants change over the course of a game simulation event? As part of this study, four game simulation events were organized that included students, professionals and diverse stakeholder groups working in watershed management contexts across Eastern Canada with 40 participants in total. Participants were divided into teams of 3–5 members and were surveyed and their interactions recorded. An interaction and social network analysis of the audiovisual recordings of each game simulation event indicates that interactions between participants increase in both quantity and quality as the game progresses. The analysis shows that serious game simulations provide an intervention platform not only to facilitate cross-boundary interactions, but also to strengthen relationships between diverse stakeholders, as expressed by an increase in mutual trust and empathy, as well as an improved understanding among the participants of the watershed system and the complex issues at stake.