Search Results (30)

The integrated development of urban agglomerations strengthens regional connectivity and supports balanced regional development. However, population shrinkage persists in some counties of the Chengdu–Chongqing Economic Circle despite increasingly close regional linkages. From the perspective of regional network embeddedness, this study examines the relationship between different types of regional linkages and the heterogeneous patterns of county-level population shrinkage. Taking 142 counties and districts in the CCEC as the research units, and drawing on multi-source panel data from 2002 to 2022, this study constructs four types of regional linkages: transportation linkages, corporate organizational linkages, executive interlock linkages, and ownership-based corporate investment linkages. Fixed-effects panel models and ordered logistic regression models are then employed to examine the associations of different network linkages with county-level population change and the degree of population shrinkage. By comparing these four network layers within the same county-level framework, the study distinguishes the roles of accessibility, corporate organization, executive relations, and ownership ties. Network evolution was uneven. The dual-core pattern weakened in the transportation and executive interlock networks, while corporate investment became more centralized. These changes describe network topology, whereas population growth remained concentrated in Chengdu, Chongqing, and adjoining districts. Between 2002 and 2022, 89 of the 142 counties in the CCEC experienced population shrinkage, accounting for 62.7% of the sample. These shrinking counties gradually clustered in peripheral areas, including northeastern Sichuan, southern Sichuan, and northeastern Chongqing, resulting in the coexistence of core growth and peripheral shrinkage. Moran’s I increased from 0.0015 in 2002–2007 to 0.1659 in 2017–2022, indicating increasing spatial clustering. The full-sample panel analysis indicates that higher centrality in the transportation, corporate organizational, and corporate investment networks is significantly associated with higher county-level population change rates, indicating either stronger growth or a smaller decline, whereas executive interlock linkages are negatively associated with population change. Further analysis of shrinking counties shows that higher corporate organizational and corporate investment centrality is significantly associated with lower shrinkage severity. By contrast, transportation and executive interlock centrality are not significantly associated with shrinkage severity. Therefore, the positive full-sample association for transportation centrality should not be interpreted as evidence that transportation network expansion generally compensates for metropolitan concentration. These findings suggest that county-level population shrinkage does not simply result from a lack of regional connections, but is closely related to the specific types of networks in which counties are embedded. Corporate organizational and corporate investment networks exhibit more stable statistical associations across both model settings, indicating that increased regional connectivity does not necessarily lead to balanced county-level development. Full article

Polymer-fiber weft-knitted textiles are widely used in functional apparel and moisture-management materials, but their complex loop topology, yarn-level porosity, and interlayer hierarchy make simulation-oriented geometric modeling challenging. Conventional control-point and interpolated-curve methods often have limitations in representing knitting actions, maintaining yarn-path continuity, and generating meshable geometries. This study proposes a rule-driven geometric modeling method for polymer-fiber weft-knitted structures using the yarn centerline as the basic geometric carrier. Knitting actions, including knit, tuck, float, plating, and double-needle-bed assignment, are converted into reusable local path-generation rules and integrated through pattern-matrix input, action recognition, parametric centerline generation, continuous stitching, and standardized output. The method represents single-bed and double-bed structures within a unified framework, including plain, jacquard, plated, tuck, rib, interlock, half-cardigan, full-cardigan, and purl structures. Compared with an interpolated-curve method, the curvature-jump rate of four representative structures decreases from 40.78–69.23% to 0–0.31%, with markedly reduced maximum bending angles. Mesh-generation results show continuous meshes with improved element quality for complex double-bed structures. A moisture-transfer simulation of a fully plated plain-knitted structure gives one-way transport indices of −122.3187 and 122.2472 for face- and back-side liquid entry, with relative errors of 1.74% and 0.50% compared with experiments. These results indicate that the proposed method provides reproducible and meshable geometric input for structure–property modeling and moisture-transfer prediction of polymer-fiber knitted textiles. Full article

High-water-content dredged sludge is difficult to reuse in building foundation systems because its loose fabric, high void ratio and low initial bearing capacity may lead to inadequate construction-stage support and excessive service deformation. This study evaluates a self-developed RT mineral-based cementitious binder for converting dredged sludge into an engineered geomaterial for potential foundation-ground improvement materials. Unconfined compressive strength tests, full stress–strain responses, SEM observation, image-based pore-topology quantification and a fractal poromechanics model were integrated to link mix design, microstructural reconstruction and foundation-related performance. The RT binder generated rapid early strength in the high-water-content sludge. At 3 d, UCS increased from approximately 0.9 MPa at 3% binder dosage to 2.15 MPa at 11% dosage; the 8% mixture reached 1.34 MPa, exceeding the 1.0 MPa material-scale screening level adopted for comparing stabilized foundation-ground candidates. Strength at 8% dosage continued to increase with curing age, although the gain rate decreased after 7 d, indicating rapid early skeleton formation followed by slower structural maturation. Microstructural evidence showed that the improvement was not governed by pore filling alone. C-S-H-like gel phases wrapped and cemented soil particles, whereas needle-like crystals consistent with ettringite morphology bridged and interlocked interparticle spaces, transforming the originally loose sludge fabric into a continuous three-dimensional load-bearing skeleton. The pore area fraction decreased from approximately 51% in untreated sludge to 31.2% at 8% dosage, while the fractal dimension increased to 1.85–1.98. The proposed fractal poromechanics model predicted UCS within ±10% of measured values, confirming that skeleton continuity and pore-topology reconstruction are key descriptors of macroscopic hardening. These findings demonstrate that RT-stabilized dredged sludge is a promising material-scale candidate for building-foundation ground improvement, provided that project-specific bearing capacity, settlement, compaction and durability requirements are further verified. Full article

Polymer–metal hybrid composites (PMHCs) represent an emerging class of materials that combine the lightweight processability of polymers with the structural and functional advantages of metals. Recent advances in material design and manufacturing have shifted attention from traditional particulate or fibrous reinforcement toward metallic architectures—continuous, architected, or topologically optimized metallic networks intentionally embedded within polymer matrices. These metallic architectures play a key role in defining the composite’s global performance, influencing stiffness, energy absorption, failure mechanisms, and multifunctional properties such as electrical or thermal conductivity. This review examines how the geometry, connectivity, and topology of metallic reinforcements govern mechanical behavior and functional responses in PMHCs. Emphasis is placed on the interplay between architecture and interface design, including surface modification strategies and mechanical interlocking phenomena. Furthermore, the paper discusses the contribution of additive manufacturing technologies in enabling complex metallic architectures and hybrid processing routes. By integrating structural, interfacial, and manufacturing perspectives, this review develops a coherent framework for understanding how metallic architecture drives the evolution of PMHCs toward multifunctional and design-driven engineering applications. The analysis of the literature consistently indicates that architectural configuration—rather than material selection alone—represents the primary factor governing multifunctional performance. Full article

This study examines the torsional behavior of an additively manufactured bushing featuring a unique topology, which includes a flexible gyroid core and rigid inner and outer sleeves. The bushing is designed and fabricated using two materials: thermoplastic polyurethane (TPU) and polylactic acid (PLA), which are interpenetrated in successive layers throughout the bushing’s thickness. First, tensile mechanical tests are conducted on both materials with different infill patterns. The 45/135 infill proves to be the most suitable, providing good stiffness, strength, ductility, and data reproducibility. Additionally, the effectiveness of the interlocking created between the two materials through the printing process is evaluated by testing different overlap lengths. With an overlap of 2 mm, the extrusion process remains unaffected, minimizing voids and defects while ensuring strong interlayer bonding. Next, the designed bushing is subjected to torsional loading under both single and repetitive angular rotations, and its response is measured in terms of torque. The aim of this study is to evaluate the suitability of TPU and PLA materials for developing a design intended for dynamic mechanical environments, serving as a proof of concept. The quasi-static results indicate the presence of local damages and a viscoelastic response of the bushing during twisting, while also demonstrating its strong ability to withstand significant angles of rotation. Quasi-static results indicate local damage and the bushing’s viscoelastic response during twisting, as well as its ability to withstand significant angles of rotation. Full article

This study assessed the effect of slicer-made interlocking joints on 3D printed sandwich panels manufactured through fused filament fabrication (FFF) in terms of flexural properties and energy absorption. Composites were prepared with thermoplastic polyurethane (TPU) as the core material and polyamide (PA), polylactic acid (PLA), polyethylene terephthalate (PET) as skin materials for each of the three composites, respectively. In order to assess the implications of internal geometry, 3D printing was done on five infill topologies (Cross-3D, Grid, Gyroid, Line and Honeycomb) at 20% density. All samples had 20% core density and underwent three point bending testing for flexural testing. It was noted that the Grid and Gyroid cores had the best performance in terms of maximum load capacity based on stretch-dominated behavior while Cross-3D and Honeycomb had lower strengths but stable moments during the bending process. Since Cross-3D topology offered the lowest deflection, it was selected for further experiments with slicer added interlocks at the face–core interface. This study revealed the most notable improvements as gains of up to 15% in peak load, 48% in maximum deflection, and 51% in energy absorption compared with the non-interlocked designs. The PET/TPU interlocked demonstrated the best performance in terms of the energy absorption (2.45 J/mm³) and peak load (272.6 N). In contrast, the PA/TPU interlocked exhibited the best flexibility and ductility with a mid-span deformation of 21.34 mm. These results confirm that slicer-generated interlocking interfaces lead to better load capacity and energy dissipation, providing a lightweight, damage-tolerant design approach for additively manufactured sandwich beams. Full article

Laser micro-drilling was applied to Fe substrates to enhance the interfacial properties of carbon fiber-reinforced polymer/iron laminates. This architecture is referred to as a resin-interlocked Fe-CFRP hybrid composite. Inspired by human hair follicles’ exceptional adhesion and filling efficiency, novel biomimetic frustum-integrated cylindrical cavities were engineered for Fe surface modification. Experimental results demonstrate that laser-processed surfaces with varied hole geometries (conical, conical frustum, cylindrical, and frustum-integrated cylindrical cavities) exhibit significantly improved interfacial performance compared to untreated Fe controls. Specifically, RI-Fe/CFRP specimens containing frustum-integrated cylindrical cavities achieved the highest shear strength, with a 44.8% increase over non-drilled counterparts. Subsequent molecular dynamics simulations confirmed the critical role of the cavity geometry, demonstrating that the frustum-integrated cylindrical cavity elevates the Fe–Diglycidyl ether of bisphenol-A interfacial energy and van der Waals interactions by 45.44% and 50.66%, respectively, versus the flat surface. The interfacial energy enhancement mechanism via distinct hole configurations was systematically studied. Furthermore, comprehensive micro-hole topology analysis elucidated the reinforcement mechanism in resin-interlocked Fe-CFRP hybrid composites. Results demonstrate that frustum-integrated cylindrical cavities significantly enhance DGEBA-3,3′-diaminodiphenyl sulfone fluidity during interface simulation, promoting mechanical interlocking and optimized resin-filling efficiency. Laser micro-drilling effectively improves Fe-DGEBA interfacial performance. These findings provide critical insights for designing high-performance composites in aerospace and automotive applications. Full article

The rapid expansion of urban areas has increased the prevalence of impermeable surfaces, intensifying flooding risks by disrupting natural water infiltration. Permeable pavements have emerged as a sustainable alternative, capable of reducing stormwater runoff, improving surface friction, and mitigating urban heat island effects. Nevertheless, their broader implementation is often hindered by issues such as clogging and limited mechanical strength resulting from high porosity. This study examines the design of interlocking permeable blocks utilizing ultra-high-performance concrete (UHPC) to strike a balance between enhanced drainage capacity and high structural performance. A topology optimization (TO) strategy was applied to numerically model the ideal block geometry, incorporating 105 drainage channels with a diameter of 6 mm—chosen to ensure manufacturability and structural integrity. The UHPC formulation was developed using particle packing optimization with ordinary Portland cement (OPC), silica fume, and limestone filler to reduce binder content while achieving superior strength and workability, guided by rheological assessments. Experimental tests revealed that the perforated UHPC blocks reached compressive strengths of 87.8 MPa at 7 days and 101.0 MPa at 28 days, whereas the solid UHPC blocks achieved compressive strengths of 125.8 MPa and 146.2 MPa, respectively. In contrast, commercial permeable concrete blocks reached only 28.9 MPa at 28 days. Despite a reduction of approximately 30.9% in strength due to perforations, the UHPC-105holes blocks still far exceed the 41 MPa threshold required for certain structural applications. These results highlight the mechanical superiority of the UHPC blocks and confirm their viability for structural use even with enhanced permeability features. The present research emphasizes mechanical and structural performance, while future work will address hydraulic conductivity and anticlogging behavior. Overall, the findings support the use of topology-optimized UHPC permeable blocks as a resilient solution for sustainable urban drainage systems, combining durability, strength, and environmental performance. Full article

This paper presents LokAlp, a modular timber construction system invented and developed by the authors, inspired by the traditional Blockbau technique, and designed for circularity and self-construction. LokAlp utilizes standardized interlocking blocks fabricated from CLT and GLT off-cuts to optimize material reuse and minimize waste. The study explores the application of massive timber digital materials within an open modular system framework, offering an alternative to the prevailing focus on lightweight structural systems, which predominantly rely on primary engineered wood materials rather than reclaimed by-products. The research evaluates geometric adaptability, production feasibility, and on-site assembly efficiency within a computational design and digital fabrication workflow. The definition of the LokAlp system has gone through several iterations. A full-scale demonstrator constructed using the LokAlp final iteration (Mk. XII) incorporated topological enhancements, increasing connection variety and modular coherence. Comparative analyses of subtractive manufacturing via 6-axis robotic milling versus traditional CNC machining revealed a >45% reduction in cycle times with robotic methods, indicating significant potential for sustainable industrial fabrication; however, validation under operational conditions is still required. Augmented reality-assisted assembly improved accuracy and reduced cognitive load compared to traditional 2D documentation, enhancing construction speed. Overall, LokAlp demonstrates a viable circular and sustainable construction approach combining digital fabrication and modular design, warranting further research to integrate robotic workflows and structural optimization. Full article

The bending of topological interlocking (TI) plates under point loading is not smooth; it is accompanied by developing lines of localization commensurate with the symmetry of the interlocking assembly. Furthermore, the developed stage of deflection is characterized by post-peak softening. This paper proposes a new concept that explains these experimentally observed phenomena. A new model considers that due to the absence of bonding between the blocks, they assume independent rotational degrees of freedom; this is missed in the traditional modeling of TI structures. The bending resistance of TI beams relies on the elasticity of the peripheral constraint (frame or post-tensioning cables) resisting the additional loading caused by the relative rotation of blocks—a phenomenon called elbowing. This is independent of the particulars of the shape of interlocking blocks, which makes it possible to model the deflection of the TI beams as the deflection of fragmented beams consisting of parallelepiped blocks with restricted out-of-beam relative displacements. The model demonstrates that the bending of TI beams produces the experimentally observed point deflection, which is considerably different from that of conventional beams. This is a consequence of independent block rotation and elbowing. It is shown that the other consequence of block rotation with elbowing is the force–deflection relationship exhibiting a post-peak softening (apparent negative stiffness). Based on the point deflection model, it is demonstrated that oscillations of TI blocks involve a unidirectional damping with discontinuous velocity dependence. This paper develops a model of such damping. The results are important for designing flexible topological interlocking structures with energy absorption. Full article

Assessing the importance of nodes in urban rail transit systems helps enhance their ability to respond to emergencies and improve reliability in view of the fact that most of the existing methods for evaluating the importance of rail transit nodes ignore the disturbance effect of signaling system failures and are unable to objectively identify critical stations in specific disturbance scenarios. Therefore, this paper proposed a method for evaluating the importance of urban rail transit nodes in signaling system failure scenarios. The method was based on the research background of the signaling system failure that occurs most frequently and analyzed the network failure mechanism after the occurrence of a disturbance. The node importance evaluation indices were selected from the network topology and network operation performance in two aspects. The variation coefficient–VIKOR method was employed to comprehensively assess the significance of urban rail transit stations during signaling system failures. The Nanjing Metro network was also used as an example to evaluate the importance of network stations. The results showed that under the attack method of signaling system failure, most ECC and interlocking stations experienced significantly higher network performance losses compared to the original attack method, and a few interchange stations showed smaller performance losses. The critical stations identified based on the proposed method are mainly distributed in the passenger flow backbone of the Nanjing Metro and were constructed in the early stage; of these, 85% are ECC stations or interlocking stations, which are easily neglected in daily management, in contrast to interchange stations with heavy passenger flow. The results of this study can provide an important reference for the stable operation and sustainable construction of urban rail transit. Full article

A topological interlocking assembly (TIA) is an assembly of blocks together with a non-empty subset of blocks called the frame such that every non-empty set of blocks is kinematically constrained and can therefore not be removed from the assembly without causing intersections between blocks of the assembly. TIA provides a wide range of real-world applications, from modular construction in architectural design to potential solutions for sound insulation. Various methods to construct TIA have been proposed in the literature. In this paper, the approach of constructing TIA by applying the Escher trick to tilings of orientable surfaces is discussed. First, the strengths of this approach are highlighted for planar tilings, and the Escher trick is then exploited to construct a planar TIA that is based on the truncated square tiling, which is a semi-regular tiling of the Euclidean plane. Next, the Escher-Like approach is modified to construct TIAs that are based on arbitrary orientable surfaces. Finally, the capabilities of this modified construction method are demonstrated by constructing TIAs that are based on the unit sphere, the truncated icosahedron, and the deltoidal hexecontahedron. Full article

This research explores the SL-Block system within an architecture framework by embracing building modularity, combinatorial design, topological interlocking, machine learning, and tactile sensor-based robotic assembly. The SL-Block, composed of S and L-shaped tetracubes, possesses a unique self-interlocking feature that allows for reversible joining and the creation of various 2D or 3D structures. In architecture modularity, the high degree of reconfigurability and adaptability of the SL-Block system introduces a new element of interest. Unlike modularization strategies that emphasize large-scale volumetric modules or standardized building components, using small-scale generic building blocks provides greater flexibility in maximizing design variations and reusability. Furthermore, the serial repetition and limited connectivity of building elements reduce the efforts required for bespoke manufacturing and automated assembly. In this article, we present our digital design and robotic assembly strategies for developing dry-jointed modular construction with SL-Blocks. Drawing on combinatorics and graph theory, we propose computational design methods that can automatically generate hierarchical SL-Block assemblies from given shapes. To address the physical complexities of contact-rich assembly tasks, we develop robotics using two distinct methods: pre-programmed assembly and sensor-based reinforcement learning. Through a series of demonstrators, we showcase the ability of SL-Blocks not only to reconfigure conventional building tectonics but also to create new building configurations. Full article

Research on topological interlocking (TI) assemblies indicates that the geometry of blocks plays a significant role in the performance of a configuration. The current TI generation methods can return assemblies of uniform antiprisms, tetrahedra, cubes, and octahedra. However, other shapes (both convex and concave) are well qualified for use in TI assemblies. This paper presents a framework to generate blocks for TI assembly. Starting from a seed polygon, evolution steps translate and reshape the polygon, contracting it eventually to a point, a line segment, or another polygon. Our framework generalizes and unifies previous-generation methods based on tilting angles and height parameters. We show how the proposed method systematically generates novel TI solids and previously reported others. Full article

Topological interlocking assembly (TIA) and computational architecture treat form as an emergent property of a material system, where the final shape results from the interplay of geometries and geometric interdependencies influenced by contextual constraints (material, structure, and fabrication). This paper posits that TIA is an ideal pedagogical tool for introducing students to computational architecture, and its theoretical foundations and design principles. Specifically, defining TIA as a material system provides a robust educational approach for engaging students with computation; fostering design processes through bottom-up, hands-on investigations; expressing design intents as procedural logic; understanding generative geometric rules; and exploring the flexibility of parametric variations. The methodology is detailed and illustrated through a design workshop and study unit from the Bachelor’s and Master’s programs at the Faculty for the Built Environment, University of Malta. Four case studies of TIA—of tetrahedra, cones, octahedra, and osteomorphic blocks—demonstrate how these exercises introduce students to computational thinking, parametric design, and fabrication techniques. This paper discusses the advantages and limitations of this pedagogical methodology, concluding that integrating computational architecture in education shifts students’ design processes to investigation and innovation-based approaches, enabling them to address contemporary design challenges through context-driven solutions. Full article