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16 pages, 1496 KiB  
Article
Evaluation of Cutting Forces and Roughness During Machining of Spherical Surfaces with Barrel Cutters
by Martin Reznicek, Cyril Horava and Martin Ovsik
Materials 2025, 18(15), 3630; https://doi.org/10.3390/ma18153630 (registering DOI) - 1 Aug 2025
Abstract
Barrel tools are increasingly used in high-precision machining of free-form surfaces. However, limited studies evaluate their performance specifically on spherical geometries, where tool–surface contact characteristics differ significantly. Understanding how tool geometry and process parameters influence surface quality and cutting forces in such cases [...] Read more.
Barrel tools are increasingly used in high-precision machining of free-form surfaces. However, limited studies evaluate their performance specifically on spherical geometries, where tool–surface contact characteristics differ significantly. Understanding how tool geometry and process parameters influence surface quality and cutting forces in such cases remains underexplored. This study evaluates how barrel cutter radius and varying machining parameters affect cutting forces and surface roughness when milling internal and external spherical surfaces. Machining tests were conducted on structural steel 1.1191 using two barrel cutters with different curvature radii (85 mm and 250 mm) on a 5-axis CNC machine. Feed per tooth and radial depth of cut were systematically varied. Cutting forces were measured using a dynamometer, and surface roughness was assessed using the Rz parameter, which is more sensitive to peak deviations than Ra. Novelty lies in isolating spherical surface shapes (internal vs. external) under identical path trajectories and systematically correlating tool geometry to force and surface metrics. The larger curvature tool (250 mm) consistently generated up to twice the cutting force of the smaller radius tool under equivalent conditions. External surfaces showed higher Rz values than internal ones due to less favorable contact geometry. Radial depth of the cut had a linear influence on force magnitude, while feed rate had a limited effect except at higher depths. Smaller-radius barrel tools and internal geometries are preferable for minimizing cutting forces and achieving better surface quality when machining spherical components. The aim of this paper is to determine the actual force load and surface quality when using specific cutting conditions for internal and external spherical machined surfaces. Full article
(This article belongs to the Special Issue Recent Advances in Precision Manufacturing Technology)
23 pages, 8564 KiB  
Article
VisRep: Towards an Automated, Reflective AI System for Documenting Visualisation Design Processes
by Aron E. Owen and Jonathan C. Roberts
Mach. Learn. Knowl. Extr. 2025, 7(3), 72; https://doi.org/10.3390/make7030072 - 25 Jul 2025
Viewed by 212
Abstract
VisRep (Visualisation Report) is an AI-powered system for capturing and structuring the early stages of the visualisation design process. It addresses a critical gap in predesign: the lack of tools that can naturally record, organise, and transform raw ideation, spoken thoughts, sketches, and [...] Read more.
VisRep (Visualisation Report) is an AI-powered system for capturing and structuring the early stages of the visualisation design process. It addresses a critical gap in predesign: the lack of tools that can naturally record, organise, and transform raw ideation, spoken thoughts, sketches, and evolving concepts into polished, shareable outputs. Users engage in talk-aloud sessions through a terminal-style interface supported by intelligent transcription and eleven structured questions that frame intent, audience, and output goals. These inputs are then processed by a large language model (LLM) guided by markdown-based output templates for reports, posters, and slides. The system aligns free-form ideas with structured communication using prompt engineering to ensure clarity, coherence, and visual consistency. VisRep not only automates the generation of professional deliverables but also enhances reflective practice by bridging spontaneous ideation and structured documentation. This paper introduces VisRep’s methodology, interface design, and AI-driven workflow, demonstrating how it improves the fidelity and transparency of the visualisation design process across academic, professional, and creative domains. Full article
(This article belongs to the Section Visualization)
20 pages, 4182 KiB  
Article
A Soft Reconfigurable Inverted Climbing Robot Based on Magneto-Elastica-Reinforced Elastomer
by Fuwen Hu, Bingyu Zhao and Wenyu Jiang
Micromachines 2025, 16(8), 855; https://doi.org/10.3390/mi16080855 - 25 Jul 2025
Viewed by 300
Abstract
This work presents a novel type of soft reconfigurable mobile robot with multimodal locomotion, which is created using a controllable magneto-elastica-reinforced composite elastomer. The rope motor-driven method is employed to modulate magnetics–mechanics coupling effects and enable the magneto-elastica-reinforced elastomer actuator to produce controllable [...] Read more.
This work presents a novel type of soft reconfigurable mobile robot with multimodal locomotion, which is created using a controllable magneto-elastica-reinforced composite elastomer. The rope motor-driven method is employed to modulate magnetics–mechanics coupling effects and enable the magneto-elastica-reinforced elastomer actuator to produce controllable deformations. Furthermore, the 3D-printed magneto-elastica-reinforced elastomer actuators are assembled into several typical robotic patterns: linear configuration, parallel configuration, and triangular configuration. As a proof of concept, a few of the basic locomotive modes are demonstrated including squirming-type crawling at a speed of 1.11 mm/s, crawling with turning functions at a speed of 1.11 mm/s, and omnidirectional crawling at a speed of 1.25 mm/s. Notably, the embedded magnetic balls produce magnetic adhesion on the ferromagnetic surfaces, which enables the soft mobile robot to climb upside-down on ferromagnetic curved surfaces. In the experiment, the inverted ceiling-based inverted crawling speed is 2.17 mm/s, and the inverted freeform surface-based inverted crawling speed is 3.40 mm/s. As indicated by the experimental results, the proposed robot has the advantages of a simple structure, low cost, reconfigurable multimodal motion ability, and so on, and has potential application in the inspection of high-value assets and operations in confined environments. Full article
(This article belongs to the Special Issue Development and Applications of Small-Scale Soft Robotics)
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21 pages, 309 KiB  
Article
Using Large Languge Models for Processing Sensor Data
by Maciej Hojda
Sensors 2025, 25(14), 4380; https://doi.org/10.3390/s25144380 - 13 Jul 2025
Viewed by 297
Abstract
The wide availability of sensor data stored in multiple formats makes it difficult to reuse in other applications. We consider the problem of extracting sensor data from unstructured and semi-structured texts using Large Language Models. With careful prompt crafting, we have been able [...] Read more.
The wide availability of sensor data stored in multiple formats makes it difficult to reuse in other applications. We consider the problem of extracting sensor data from unstructured and semi-structured texts using Large Language Models. With careful prompt crafting, we have been able to establish a strict JSON structure which can be further processed with automated ease. We establish a workflow that enables the extraction of data using GPT-4, Llama 3, Mistral and Falcon models, and we show that while the closed-source GPT-4 model is generally leading in conversion efficiency, other open-source models can follow this if given appropriate data structures. We define new measures to simplify the comparison, and we present a multi-purpose workflow for sensor data extraction. We observe that some of the smaller models are incapable of correctly extracting data from freeform text but are skilled in processing tabular data. On the other hand, larger models are more robust and avoid conversion mistakes more easily. Full article
(This article belongs to the Section Intelligent Sensors)
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11 pages, 2586 KiB  
Communication
Full-Factorial Rheological Investigation of Carbopol ETD2020 for Embedded Printing: Effects of pH and Carbomer Concentration
by Tobias Biermann, Lennart Mesecke, Simon Teves, Ivo Ziesche and Roland Lachmayer
Materials 2025, 18(13), 3164; https://doi.org/10.3390/ma18133164 - 3 Jul 2025
Viewed by 378
Abstract
Embedded printing of soft materials relies on yield-stress support matrices to prevent sagging and enable freeform fabrication. The rheological parameters of the matrix material directly influence critical printing outcomes such as strand positioning, cavity formation, structural stability, and defect suppression in embedded printing. [...] Read more.
Embedded printing of soft materials relies on yield-stress support matrices to prevent sagging and enable freeform fabrication. The rheological parameters of the matrix material directly influence critical printing outcomes such as strand positioning, cavity formation, structural stability, and defect suppression in embedded printing. Despite widespread use of Carbopol® formulations, a systematic rheological characterization of ETD2020 across relevant polymer concentrations and pH levels for embedded printing is lacking. Here, we implement a full-factorial design with polymer concentrations from 0.1wt% to 0.9wt% and triethanolamine dosages of 30–50µL per 100g. Steady-shear (0.001200s1) and oscillatory (1Hz) rheometry yielded Herschel–Bulkley parameters τy, k, n as well as storage and loss modulus G/G. All formulations exhibited pronounced shear-thinning, with τy increasing nonlinearly from <1Pa to 41.1Pa and G reaching 400Pa at 0.9wt%. A five-hour window of invariant rheology was identified, followed by a Δτy10Pa increase after five days, indicating delayed polymerization. The comprehensive material characterization defines a rheological window for ETD2020 and facilitates simulation-based modeling and the targeted tuning of matrix properties. Heatmaps provide an interpolated depiction of combined carbomer and triethanolamine concentrations, enabling tunable support matrices for embedded printing. Full article
(This article belongs to the Special Issue Novel Materials for Additive Manufacturing)
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14 pages, 4339 KiB  
Article
Discrimination of Smoke-Exposed Pinot Noir Wines by Volatile Phenols and Volatile Phenol-Glycosides
by Armando Alcazar-Magana, Ruiwen Yang, Michael C. Qian and Yanping L. Qian
Molecules 2025, 30(13), 2719; https://doi.org/10.3390/molecules30132719 - 24 Jun 2025
Viewed by 308
Abstract
This study investigated the correlation between five primary volatile phenols (VPs) and their glycosides in smoke-exposed and non-smoke-exposed Pinot noir wines to assess and identify potential markers for smoke taint. The results showed that all putative VP-glycosides in smoke-exposed wines were higher than [...] Read more.
This study investigated the correlation between five primary volatile phenols (VPs) and their glycosides in smoke-exposed and non-smoke-exposed Pinot noir wines to assess and identify potential markers for smoke taint. The results showed that all putative VP-glycosides in smoke-exposed wines were higher than in non-smoke-exposed wines, with a fold change ranging from 2.11 to 31.88 for the top fifteen differentiations. VP-glycosides showed strong positive correlations among themselves, with correlation coefficients of 0.94 for hexose-guaiacol vs. pentose (P)-hexose (H)-cresol and 0.92 for syringyl-β-D-glucopyranoside vs. H-P-4-methylguaiacol. VP-glycosides also showed relatively high correlations with free and strong acid-hydrolyzed VPs. The correlation coefficient between H-P-guaiacol and free-form guaiacol is 0.71, and between H-P-guaiacol and total guaiacol is 0.78. The strong correlation suggests that these compounds are interconnected and regulated by the severity of smoke exposure. Multivariate analysis effectively differentiated smoke-exposed wines from non-smoke-exposed ones. However, more research is needed to fill the gaps in understanding smoke-derived compounds. Full article
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14 pages, 1238 KiB  
Article
Optimization of Solid Lipid Microcapsule Matrix for Enhanced Release and Bioavailability of L-Lysine in Swine
by Costanza Bonnici, Maria Federica Marchesi, Martina Felici, Federico Ghiselli, Roberta Majer, Benedetta Tugnoli, Guglielmo Gallina, Andrea Piva and Ester Grilli
Animals 2025, 15(12), 1806; https://doi.org/10.3390/ani15121806 - 19 Jun 2025
Viewed by 332
Abstract
L-lysine (L-Lys) is the first-limiting amino acid in swine nutrition, but free-form supplements exhibit poor intestinal absorption, reducing their bioavailability. This study aimed to enhance the gastric retention, controlled intestinal release, and systemic availability of L-Lys by optimizing solid lipid microcapsules (SLMs). SLMs [...] Read more.
L-lysine (L-Lys) is the first-limiting amino acid in swine nutrition, but free-form supplements exhibit poor intestinal absorption, reducing their bioavailability. This study aimed to enhance the gastric retention, controlled intestinal release, and systemic availability of L-Lys by optimizing solid lipid microcapsules (SLMs). SLMs were formulated using hydrogenated triglycerides (C16:0 or C18:1), free fatty acids, and varying emulsifier concentrations. Gastric retention and intestinal release were evaluated in vitro under simulated gastrointestinal conditions (a pepsin buffer at pH 5.0 for 2 h, followed by a pancreatin buffer at pH 6.5 for up to 8 h at 39 °C). SLMs with hydrogenated triglycerides showed significantly higher gastric retention (94–95%) than those with free fatty acids (48%). Specifically, C16:0 triglyceride-based SLMs achieved 74% intestinal release, which was enhanced to 90% with 1% emulsifier. This refined formulation was subsequently evaluated in vivo using weaned pigs (three groups; n = 4) fed a basal cornmeal diet. The treatments included a single oral administration of saline solution (placebo), free L-Lys (0.17 g/kg BW), or L-Lys SLMs (0.38 g/kg BW, equally providing L-Lys at 0.17 g/kg BW). The SLMs delayed the L-Lys plasma peak (T. max. 3–4 h vs. 1 h) and significantly increased the total L-Lys amount in the plasma over 24 h, demonstrating the enhanced relative bioavailability of encapsulated L-Lys. Full article
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15 pages, 4842 KiB  
Article
Dynamic Spatial Small-Target Simulation System with Long-Exit Pupil Distance
by Yi Lu, Xiping Xu, Ning Zhang, Yaowen Lv and Hua Geng
Photonics 2025, 12(6), 578; https://doi.org/10.3390/photonics12060578 - 6 Jun 2025
Viewed by 322
Abstract
System architecture was developed to solve the issues of short pupil distance and mismatch between the simulated wavelength range and the sensor in the simulator of small targets in space. The system consists of Liquid Crystal on Silicon (LCOS), a Polarizing Beam Splitter [...] Read more.
System architecture was developed to solve the issues of short pupil distance and mismatch between the simulated wavelength range and the sensor in the simulator of small targets in space. The system consists of Liquid Crystal on Silicon (LCOS), a Polarizing Beam Splitter (PBS), a dual free-form surface-illumination system, and a long-exit-pupil-distance projection system. The innovatively designed long exit pupil distance projection system can achieve an exit pupil distance of 1250 mm, covering the visible and near-infrared bands from 400 to 950 nm. The dual free-form surface-illumination system reaches a divergence angle of ±4.3° and an illumination non-uniformity of 4.7%. Experimental validation shows that the system’s star position error is better than −3.94″, and the angular distance error between stars does not exceed −7.69″. The radiation simulation accuracy for stars ranging from magnitude 3 to 6 is between −0.049 and 0.085 magnitudes, demonstrating high-precision simulation capabilities for both geometric and radiation characteristics. The research results set a critical theoretical foundation for the development of high-fidelity space target simulators, and the proposed dual free-form surface-design method and wide-spectrum aberration compensation technology provide a new paradigm for precision optical system design. Full article
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20 pages, 8024 KiB  
Article
Morphology and Solidity Optimization of Freeform Surface Turbulators for Heat Exchangers Equipped with Narrow Channels
by Maria Corti, Roberta Caruana, Antonio Di Caterino, Damiano Fustinoni, Pasqualino Gramazio, Luigi Vitali and Manfredo Guilizzoni
Energies 2025, 18(11), 2903; https://doi.org/10.3390/en18112903 - 1 Jun 2025
Viewed by 723
Abstract
Improving the thermal performance of compact heat exchangers is a key challenge in the development of energy-efficient systems. This work investigates the use of topology optimization to generate novel surface geometries that enhance thermal efficiency specifically in narrow rectangular channels. A physics-based topology [...] Read more.
Improving the thermal performance of compact heat exchangers is a key challenge in the development of energy-efficient systems. This work investigates the use of topology optimization to generate novel surface geometries that enhance thermal efficiency specifically in narrow rectangular channels. A physics-based topology optimization software, ToffeeX, has been employed to explore turbulator designs within defined spatial and material constraints. The optimization process has focused on maximizing heat transfer, with particular attention on the effect of solid volumetric fraction. Simulations have been carried out using the CFD tools of the optimization software to evaluate the thermal behavior of the proposed configurations. Among the tested designs, a solid volumetric fraction of 8% has led to the most effective solution, achieving a 25% increase in outlet fluid temperature compared to a conventional ribbed reference configuration. Validation using CFD simulations with another package, OpenFOAM, has confirmed these results, showing consistent trends across methodologies. These findings highlight the potential of combining topology optimization with numerical simulation to develop advanced geometries for heat transfer enhancement. The proposed approach supports the development of more efficient and compact heat exchangers, paving the way for future experimental studies and broader industrial applications. Full article
(This article belongs to the Special Issue Computational Fluid Dynamics (CFD) Study for Heat Transfer)
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18 pages, 5991 KiB  
Article
The Intraoperative Fabrication of PMMA Patient-Specific Enophthalmos Wedges and Onlays for Post-Traumatic OZC Reconstruction
by Layton Vosloo
Craniomaxillofac. Trauma Reconstr. 2025, 18(2), 29; https://doi.org/10.3390/cmtr18020029 - 29 May 2025
Viewed by 1973
Abstract
Objective: Trauma is a leading cause of enophthalmos, typically resulting from an increase in the volume of the bony orbit. The general consensus is that post-traumatic primary deformity repair should aim to restore the premorbid volume, shape, and cosmesis of the orbitozygomatic complex [...] Read more.
Objective: Trauma is a leading cause of enophthalmos, typically resulting from an increase in the volume of the bony orbit. The general consensus is that post-traumatic primary deformity repair should aim to restore the premorbid volume, shape, and cosmesis of the orbitozygomatic complex (OZC). This study aims to utilise novel three-dimensional (3D) printed patient-specific moulds to intraoperatively fabricate enophthalmos wedges and onlays using polymethylmethacrylate (PMMA) bone cement to reconstruct the OZC. Methods: A total of seven patients underwent digital surgical planning using Freeform software to virtually correct orbitozygomatic complex deformities guided by a design algorithm. Three-dimensionally printed nylon patient-specific moulds were used intraoperatively to fabricate enophthalmos wedges and/or onlays using an industry-standard PMMA bone cement. Clinical examination and application of the proposed design algorithm determined that enophthalmos wedges were indicated for four patients, with one also requiring an onlay; and periorbital onlays were required for the three remaining patients. Results: Hertel exophthalmometry at a mean follow-up of 19.1 months demonstrated good outcomes in the correction of post-traumatic enophthalmos and hypoglobus and with patients reporting good subjective cosmetic results. Patients 5 and 7 had follow-up three-dimensional computed tomography (3D-CT) to confirm correct placement. Conclusion: The use of patient-specific PMMA wedges and onlays, fabricated intraoperatively with the aid of 3D-printed moulds, offers a reliable and effective approach for correcting post-traumatic enophthalmos and hypoglobus. This method allows for the restoration of orbital volume and anatomical contours, addressing both functional and aesthetic concerns. Our results demonstrate that this technique yields favourable outcomes. Full article
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25 pages, 3990 KiB  
Article
Study on Trajectory Planning for Polishing Free-Form Surfaces of XY-3-RPS Hybrid Robot
by Xiaozong Song, Junfeng An and Xingwu Ma
Actuators 2025, 14(6), 269; https://doi.org/10.3390/act14060269 - 29 May 2025
Viewed by 512
Abstract
Free-form surface polishing is a key process in precision machining within high-end manufacturing, where optimizing the polishing trajectory directly influences both processing quality and efficiency. Traditional trajectory planning methods for free-form surface polishing in high-curvature regions suffer from issues such as a lack [...] Read more.
Free-form surface polishing is a key process in precision machining within high-end manufacturing, where optimizing the polishing trajectory directly influences both processing quality and efficiency. Traditional trajectory planning methods for free-form surface polishing in high-curvature regions suffer from issues such as a lack of precision, low trajectory continuity, and inefficiency. This paper proposes an improved trajectory planning method based on curvature characteristics, incorporating dynamic partitioning and boundary smoothing algorithms. These methods dynamically adjust according to surface curvature, enhancing processing efficiency and surface quality. Additionally, a hybrid optimization framework combining a genetic algorithm (GA) and local search (LS) is proposed to address the challenges of balancing global optimization with local fine-tuning in traditional trajectory planning methods. These challenges often result in large errors, low machining efficiency, and unstable surface quality. The method optimizes the overall trajectory distribution through a global search using GA while locally refining the high-curvature regions with LS. This combination improves trajectory uniformity and smoothness, and the results demonstrate significant increases in machining efficiency and accuracy. Finally, the feasibility of the trajectory planning method was verified through motion simulation. This paper also provides a detailed description of the mathematical modeling, algorithm implementation, and simulation analysis of the XY-3-RPS hybrid robot for trajectory optimization, offering both a theoretical foundation and engineering support for its application in free-form surface polishing. Full article
(This article belongs to the Section Actuators for Robotics)
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33 pages, 12429 KiB  
Article
Segmented Timber Shells for Circular Construction: Relocation, Structural Assessment, and Robotic Fabrication of a Modular, Lightweight Timber Structure
by Simon Bechert, Simon Aicher, Lyudmila Gorokhova, Laura Balangé, Monika Göbel, Volker Schwieger, Achim Menges and Jan Knippers
Buildings 2025, 15(11), 1857; https://doi.org/10.3390/buildings15111857 - 28 May 2025
Viewed by 788
Abstract
Segmented timber shells present a novel building system that utilizes modular, planar building components to create lightweight free-form structures in architecture. Recent advancements in the research field of segmented timber shells pursue, among others, two fundamentally opposing research objectives. 1. The modularity of [...] Read more.
Segmented timber shells present a novel building system that utilizes modular, planar building components to create lightweight free-form structures in architecture. Recent advancements in the research field of segmented timber shells pursue, among others, two fundamentally opposing research objectives. 1. The modularity of their building components facilitates the reuse of such structures in response to a changing built environment. 2. Advanced developments aim at establishing segmented timber shells as permanent building structures for sustainable architecture. This paper addresses the first research objective through the successful relocation of the BUGA Wood Pavilion in the context of the proposed methodology of Co-Design for circular construction. The methods and results involve integrative design and engineering processes and advanced quality assessment methods, including structural, geodetic, and physical properties for modular timber constructions. The BUGA Wood Pavilion serves as a building demonstrator for the presented research on segmented shells as lightweight, reusable, and durable timber structures. Full article
(This article belongs to the Section Building Structures)
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12 pages, 5288 KiB  
Article
The Effect of Nodal Deviation on the Reliability Performance of the Optimized Free-Form Single-Layer Reticulated Shell
by Dong Li and Baoshi Jiang
Appl. Sci. 2025, 15(10), 5379; https://doi.org/10.3390/app15105379 - 12 May 2025
Viewed by 286
Abstract
The free-form single-layer reticulated shell structure has the characteristics of complex shape, a high degree of static indeterminacy, and difficult node positioning in the construction process, and the nodal deviations that may occur in the construction stage have a significant impact on the [...] Read more.
The free-form single-layer reticulated shell structure has the characteristics of complex shape, a high degree of static indeterminacy, and difficult node positioning in the construction process, and the nodal deviations that may occur in the construction stage have a significant impact on the reliability performance of the structure. In order to evaluate the influence of the nodal deviation on the reliability performance of the structure in the process of shape optimization, this paper takes the free-form surface of the rectangular plane as the initial structure. Shape optimization is carried out with the objective function of minimizing the strain energy under the uniform vertical load, and the influence of the nodal deviation on the reliability performance of the optimized structure is performed by analyzing changes in the structural response’s probability density function (PDF). The elastic modulus, yield strength, and nodal deviation of the material were selected as the basic random variables, and the PDF of the structural response was calculated using the probability density evolution method. In the case of considering and ignoring the nodal deviation, respectively, the PDF of the maximum displacement response of the structure under the same iteration step is calculated and compared. The results indicate that compared with the initial structure, the reliability performance of the optimized structure is significantly less sensitive to node deviations. Full article
(This article belongs to the Section Civil Engineering)
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13 pages, 5808 KiB  
Article
A Point Cloud Registration Method Based on Point-to-Triangulation Estimation for Optical Window Free-Form Surfaces Testing by Coordinate Measuring Machine
by Chuanchao Wu, Junjie Shi, Taorui Li, Haijiao Huang, Fudong Chu, Siyuan Jiang, Longyue Li and Chiben Zhang
Photonics 2025, 12(5), 469; https://doi.org/10.3390/photonics12050469 - 10 May 2025
Viewed by 382
Abstract
Optical window freeform surfaces have emerged as a critical research focus in advanced optical engineering owing to their extensive surface degrees of freedom. These surfaces enable the simultaneous correction of on-axis and off-axis aberrations while satisfying stringent requirements for high-performance, lightweight, and compact [...] Read more.
Optical window freeform surfaces have emerged as a critical research focus in advanced optical engineering owing to their extensive surface degrees of freedom. These surfaces enable the simultaneous correction of on-axis and off-axis aberrations while satisfying stringent requirements for high-performance, lightweight, and compact optical systems. In the initial metrological characterization of these surfaces, coordinate measuring machines (CMMs) are conventionally employed for target point cloud acquisition. However, the achievable measurement accuracy (>2 μm) inherently constrained by CMM precision imposes fundamental limitations for subsequent optical inspections requiring sub-micron to nanometer-level resolution. Meanwhile, although optical measurement methods can result in higher measurement accuracy, they also lead to an increase in costs and testing difficulties. To overcome these limitations, we propose an accelerated point cloud registration methodology based on point-to-triangulation distance estimation. In simulation, using optimal coordinate transformation enabled good capabilities for exceptional surface characterization: peak-to-valley (PV) surface error of 10−6 nm, residual error of 5 nm, and registration accuracy of log10 (mm/°). Further, in the experiment, the PV surface error was reduced from 27.3 μm to 6.9 μm, equivalent to a reduction of 3.95 times. These results confirm that the point-to-triangulation distance approximation maintains sufficient fidelity to the nominal point-to-surface distance, thereby empirically validating the efficacy of our proposed methodology. Notably, compared with conventional 3D alignment methods, our novel 2D estimation registration approach with point-to-triangulation surface normal vectors demonstrates significant advantages in computational complexity, which achieved a 78% reduction from O(n3) to O(n) while maintaining sub-millisecond alignment times. We believe that the method has potential for use as a low-cost optical precision measurement in manufacturing technology. Full article
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18 pages, 24615 KiB  
Article
Perceptual-Preference-Based Touring Routes in Xishu Gardens Using Panoramic Digital-Twin Modeling
by Xueqian Gong, Zhanyuan Zhu, Li Guo, Yong Zhong, Deshun Zhang, Jing Li, Manqin Yao, Wei Yong, Mengjia Li and Yujie Huang
Land 2025, 14(5), 932; https://doi.org/10.3390/land14050932 - 25 Apr 2025
Viewed by 555
Abstract
Xishu Gardens, an exemplary narrative of classical Chinese gardens, faces challenges in preserving its commemorative spatial structures while accommodating modern visitors’ needs. While trajectory analysis is critical, existing studies struggle to interpret multi-dimensional perception-preference data owing to spatiotemporal mismatches in multi-source datasets. This [...] Read more.
Xishu Gardens, an exemplary narrative of classical Chinese gardens, faces challenges in preserving its commemorative spatial structures while accommodating modern visitors’ needs. While trajectory analysis is critical, existing studies struggle to interpret multi-dimensional perception-preference data owing to spatiotemporal mismatches in multi-source datasets. This study adopted an improved Ward–K-medoids hybrid clustering algorithm to analyze 885 trajectory samples and 34,384 synchronized data points capturing emotional valence, cognitive evaluations, and dwell time behaviors via panoramic digital twins across three heritage sites (Du Fu Thatched Cottage, San Su Shrine, and Wangjiang Tower Park). Our key findings include the following: (1) Axial bimodal patterns: Type I high-frequency looping paths (27.6–68.9% recurrence) drive deep exploration, in contrast to Type II linear routes (≤0.5% recurrence), which enable intensive node coverage. (2) Layout-perception dynamics: single-axis layouts maximize behavioral engagement (DFTC), free-form designs achieve optimal emotional-cognitive integration (WTP), and multi-axis systems amplify emotional-cognitive fluctuations (SSS). (3) Spatial preference hierarchy: entrance and waterfront zones demonstrate dwell times 20% longer than site averages. Accordingly, the proposed model synchronizes Type II peak-hour throughput with Type I off-peak experiential depth using dynamic path allocation algorithms. This study underscores the strong spatial guidance mechanisms of Xishu Gardens, supporting tourism management and heritage conservation. Full article
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