Search Results (170)

A focus-control mechanism is essential for maintaining the optical performance of spaceborne telescopes, the mirror alignment of which is degraded by gravity release, moisture desorption, and thermal distortion in orbit. Achieving submicrometer-level drive accuracy is challenging because bearing deformation and bolted-joint hysteresis introduce nonlinear behavior, which must be addressed in ultraprecision mechanisms. In this study, the 1D Computer-Aided Engineering (1DCAE) approach was applied to the early-phase design of a spaceborne focus-control mechanism for developing practical design equations that accurately represent the stiffness and deformation characteristics of key components. Modification functions derived from finite element analysis (FEA) and the indirect fictitious boundary integral method (IFBIM) were incorporated into the equations for a linear guide, rectangular spring, and bearing deformation. These equations showed excellent agreement with analytical solutions, numerical simulations, and experimental data, achieving accuracies within 3% and 2.5% for the linear guide and rectangular spring, respectively, and close correspondence with the IFBIM-based bearing deformation reference values. Integrating the equations into the 1DCAE model enabled accurate prediction of the nonlinear drive characteristics of the mechanism and improved the overall drive accuracy to one-fortieth that of the initial design. In conclusion, 1DCAE provides an effective and computationally efficient framework for optimizing ultraprecision mechanisms used in space applications. Full article

As the primary power transmission conduits, aircraft hydraulic pipelines are critical for actuating flight control surfaces and landing gear systems. Accurate in situ strain evaluation of these pipelines is essential, as installation-induced pre-loads directly compromise fatigue life and sealing performance, threatening overall system reliability. However, such evaluation is frequently hindered by the perspective distortions and limited depth of field inherent in conventional imaging systems. To overcome these metrological limitations, this study presents a novel virtual telecentric camera array system designed for high-precision, non-contact strain measurement. Unlike traditional pinhole models, the proposed system leverages a catadioptric setup with planar mirrors to create a virtual four-eye telecentric array from a single physical lens, ensuring constant magnification within the depth of field. A comprehensive simulation framework was established to rigorously compare the reprojection errors and scale accuracies between telecentric and pinhole projection models, quantitatively demonstrating the superior stability of the telecentric approach. Furthermore, a dedicated calibration strategy for non-overlapping telecentric fields of view was developed and validated. Experimental results from pipeline installation tests indicate a high concordance with strain gauge data, confirming that the proposed telecentric system effectively mitigates parallax errors and provides a robust solution for static and quasi-static micro-scale deformation monitoring in complex assembly environments. Full article

We present a reference-free computational wavefront sensor based on binary amplitude modulation and phase retrieval. The method employs a Digital Micromirror Device as a programmable amplitude modulator and reconstructs the complex optical field from multiple far-field intensity measurements using the Reweighted Amplitude Flow algorithm with Optimal Spectral Initialization. Unlike classical pupil-plane wavefront sensors, the proposed architecture contains no wavelength-specific optical elements, enabling straightforward adaptation across a broad spectral range. The achievable spatial resolution of the reconstructed wavefront scales directly with the modulator resolution. We experimentally demonstrate wavefront reconstruction at 650 nm and at 2116 nm, a wavelength regime where commercial wavefront sensors are scarce. At 650 nm, the reconstructed wavefront is validated against a commercial lateral shearing interferometer, and the sensor is further integrated into a closed-loop adaptive optics system using a deformable mirror. The proposed approach is particularly suited for applications requiring high spatial resolution and large dynamic range in slowly varying or quasi-static laser fields, where computational reconstruction speed is not a primary concern. Full article

Objective: To synthesize current evidence on the relationships between adolescent idiopathic scoliosis (AIS), stress-related mechanisms, neuroanatomical asymmetry, and mental disorders, and to propose an integrative conceptual framework describing their interaction. Materials and Methods: A comprehensive literature review was conducted using the PubMed, Web of Science, and Scopus databases. Search terms targeted the etiology and pathogenesis of adolescent idiopathic scoliosis, hemispheric lateralization, stress responses, body schema disturbances, and associated mental disorders. The review was reported in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) recommendations. A structured qualitative synthesis of 225 relevant publications was performed. Results: The analyzed studies revealed several complementary conceptual approaches to AIS pathogenesis. Emerging evidence suggests that atypical hemispheric lateralization, potentially associated with right-hemisphere (RH) dysfunction, may contribute to susceptibility to AIS. Such patterns of lateralization have been linked to specific stress-related coping strategies, including harm avoidance, as well as to disturbances of body schema and an increased prevalence of certain mental disorders. Gender-related differences in stress responses and in the development and progression of AIS were consistently reported across studies. Collectively, these findings support the hypothesis that neuropsychological and stress-related mechanisms, including phenomena described as the “distorting mirror effect”, may contribute to the persistence and progression of spinal deformity in vulnerable individuals. Conclusions: AIS appears to be a multifactorial condition in which atypical neuroanatomical asymmetry, stress-related processes, and altered body representation interact. This integrative perspective generates hypotheses suggesting that prevention and treatment strategies for AIS could benefit from incorporating approaches aimed at modulating stress responses and enhancing brain neuroplasticity. Further interdisciplinary studies integrating clinical, neuroimaging, and neurobiological methods are warranted to clarify underlying mechanisms. Full article

Background: The PITX1 gene encodes a transcription factor that plays a crucial role in the development of the lower limbs, pelvis, and structures derived from the first branchial arch. Pathogenic variants in PITX1 are associated with a limited spectrum of rare disorders, including congenital talipes equinovarus with or without long bone anomalies and/or mirror-image polydactyly, and Liebenberg syndrome. In 2020, a novel clinical phenotype, Mandibular–Pelvic–Patellar (MPP) syndrome, resulting PITX1 missense variants, was proposed. Case presentation: We report the fourth documented case of MPP syndrome worldwide, identified in a 17-year-old female patient presenting with congenital lower limb deformities, patellar aplasia, and micrognathia. Whole-genome sequencing revealed a heterozygous PITX1 missense variant NM_002653.5: c.412A>C, p.(Lys138Gln). The clinical phenotype included knee flexion contractures and severe equinovarus and planovalgus foot deformities requiring multiple staged reconstructive surgical procedures. Conclusions: This case supports recognition of MPP syndrome as a clinically and genetically distinct PITX1-related disorder. Our findings expand the phenotypic spectrum of MPP syndrome and suggest that severe congenital foot deformities represent a consistent and clinically relevant feature of this condition. Full article

Cuba is in a unique situation in which it has a large (220,000 managed colonies) and isolated honey bee population due to a 60+ year ban on the importation of bees. Despite this, the ectoparasitic mite Varroa destructor arrived in 1996, and with it came deformed wing virus (DWV). In 2018, an island-wide survey detected varroa and DWV in 91% of colonies. In this study, we conducted a full-virome analysis on some of these samples, along with additional samples collected in 2021. For the first time, we detected two variants of Lake Sinai Virus and confirmed the absence of the normally widespread black queen cell virus in Cuba. We also detected both DWV-A and DWV-B master variants, with DWV-B being the dominant variant. Interestingly, the DWV-B/A recombinant was also detected, indicating that despite Cuba’s isolated nature, the pattern of DWV evolution mirrors that found in the USA and Europe. However, this pattern is not found in neighboring Latin America, China, or Japan, where the DWV-A master variant continues to be dominant. How and why two distinct evolutionary DWV pathways have arisen remain a mystery. Full article

To address the limitations of conventional wavefront sensorless adaptive optics (AO) systems regarding iteration efficiency and convergence speed, this study conducts an experimental validation of a model-based wavefront sensorless AO approach. A physical experimental platform was established, which consisted of a light source, a Shack–Hartmann wavefront sensor, a deformable mirror (DM), and an imaging detector. Wavefront aberrations under different turbulence levels were employed as correction objects to evaluate the performance of the model-based wavefront sensorless AO system. For comparative analysis, experimental results obtained by using the classical stochastic parallel gradient descent (SPGD) control algorithm are also presented. Under identical software and hardware conditions, the experimental results show that as the turbulence level increases, the SPGD-based wavefront sensorless AO system requires a larger number of iterations and exhibits a slower convergence. In contrast, the model-based wavefront sensorless AO system demonstrates improved applicability and robustness in correcting large aberrations under strong turbulence levels, maintaining an almost constant convergence speed and achieving better correction performance. These findings offer theoretical insights and technical support for the real-time correction potential of large wavefront aberrations. Full article

The Axi gold deposit, a low-sulfidation epithermal deposit in the Western Tianshan, China, hosts over 50 t of gold resources and is widely regarded as the result of coupled processes of rock deformation, heat transfer, pore fluid flow, and chemical reactions. However, research on the ore-forming processes of this gold deposit from a coupled perspective remains limited, resulting in its ore-forming mechanisms being incompletely understood. In this paper, we use the concept of mineralization rate based on computational modeling to indicate the 3D spatial distribution of mineralization. The simulation results reveal the following: (1) temperature gradients play a key role in influencing mineral precipitation, whereas the effect of pore fluid pressure gradients is relatively negligible; (2) gold precipitation, characterized by a negative mineralization rate, predominantly took place along fault zones that exhibit vertical transitions from steep to gentle slopes or lateral bends, which are further distinguished by the accumulation of fluids and the presence of significant temperature gradients. Notably, this particular distribution pattern of gold precipitation closely mirrors the spatial arrangement of known gold orebodies. These findings suggest that the coupling of multiple physical and chemical processes at specific fault sites plays a critical role in ore formation, providing new insights into the mechanisms governing the development of the Axi gold deposit. Furthermore, based on these observations, it can be inferred that the deeper regions of the Axi gold deposit hold considerable mineralization potential. Full article

Wafer-level thin-film stress measurement is essential for reliable semiconductor fabrication. However, existing techniques present limitations in practice. Interferometry achieves high precision but at a cost that becomes prohibitive for large wafers. Meanwhile laser-scanning systems are more affordable but can only provide sparse data points. This work develops a phase-measuring deflectometry (PMD) system to bridge this gap and deliver a full-field solution for wafer stress mapping. The implementation addresses three key challenges in adapting PMD. First, screen positioning and orientation are refined using an inverse bundle-adjustment approach, which performs multi-parameter optimization without re-optimizing the camera model and simultaneously uses residuals to quantify screen deformation. Second, a backward-propagation ray-tracing framework benchmarks two iterative strategies to resolve the slope-height ambiguity which is a fundamental challenge in PMD caused by the absence of a fixed optical center on the source side. The reprojection constraint strategy is selected for its superior convergence precision. Third, this strategy is integrated with regional wavefront reconstruction based on Hermite interpolation to effectively eliminate edge artifacts. Experimental results demonstrate a peak-to-valley error in the reconstructed topography of 0.48 µm for a spherical mirror with a radius of 500 mm. The practical utility of the system is confirmed through curvature mapping of a 12-inch patterned wafer and further validated by stress measurements on an 8-inch bare wafer, which show less than 5% deviation from industry-standard instrumentation. These results validate the proposed PMD method as an accurate and cost-effective approach for production-scale thin-film stress inspection. Full article

Mine-induced surface subsidence threatens infrastructure and can trigger cascading geohazards, so accurate and computationally efficient monitoring and forecasting are essential for early warning. We integrate Persistent Scatterer InSAR (PS-InSAR) time series with a Bayesian-optimized CNN–LSTM designed for spatiotemporal prediction. The CNN extracts spatial deformation patterns, the LSTM models temporal dependence, and Bayesian optimization selects the architecture, training hyperparameters, and the most informative exogenous drivers. Groundwater level and backfilling intensity are encoded as multichannel inputs. Endpoint anchoring with affine calibration aligns the historical series and the forward projections. PS-InSAR indicates a maximum subsidence rate of 85.6 mm yr⁻¹, and the estimates are corroborated against nearby leveling benchmarks and FLAC^3D simulations. Cross-site comparisons show acceleration followed by deceleration after backfilling and groundwater recovery, which is consistent with geological engineering conditions. A symmetry-aware preprocessing step exploits axial regularities of the deformation field through mirroring augmentation and documents symmetry-breaking hotspots linked to geological heterogeneity. These choices improve generalization to shifted and oscillatory patterns in both the spatial CNN and the temporal LSTM branches. Short-term forecasts from the BO–CNN–LSTM indicate subsequent stabilization with localized rebound, highlighting its practical value for operational planning and risk mitigation. The framework combines automated hyperparameter search with physically consistent objectives, reduces manual tuning, enhances reproducibility and generalizability, and provides a transferable quantitative workflow for forecasting mine-induced deformation in complex goaf systems. Full article

This paper introduces a broad class of Mirror Descent (MD) and Generalized Exponentiated Gradient (GEG) algorithms derived from trace-form entropies defined via deformed logarithms. Leveraging these generalized entropies yields MD and GEG algorithms with improved convergence behavior, robustness against vanishing and exploding gradients, and inherent adaptability to non-Euclidean geometries through mirror maps. We establish deep connections between these methods and Amari’s natural gradient, revealing a unified geometric foundation for additive, multiplicative, and natural gradient updates. Focusing on the Tsallis, Kaniadakis, Sharma–Taneja–Mittal, and Kaniadakis–Lissia–Scarfone entropy families, we show that each entropy induces a distinct Riemannian metric on the parameter space, leading to GEG algorithms that preserve the natural statistical geometry. The tunable parameters of deformed logarithms enable adaptive geometric selection, providing enhanced robustness and convergence over classical Euclidean optimization. Overall, our framework unifies key first-order MD optimization methods under a single information-geometric perspective based on generalized Bregman divergences, where the choice of entropy determines the underlying metric and dual geometric structure. Full article

This article demonstrates that 3D-printed parts can replace metal parts in optomechanics in the correct circumstances. Three examples are shown: a clamping fork for pedestal holders where stability is important, an adjustable mirror holder where the rigidity is the main criterion, and a stray light shield where the transmissivity is critical. By combining carbon-fiber-reinforced polymers (CFRPs) with 3D printing, it is possible to produce components that fill the gap between standard 3D-printed plastics and metal parts in terms of strength and stability. These parts are designed to be lighter, more compact, and easier to modify, while keeping good mechanical properties such as resistance to vibration, shape accuracy, and controlled thermal expansion. The article focuses on the application of composite 3D printing on optomechanical components. It compares different methods of composite 3D printing, including fused filament fabrication (FFF) with either chopped fibers or with continuous fiber reinforcement. Three examples from the HiLASE Centre demonstrate how these parts are used in practice, confirming that it is indeed possible to 3D print components that are lighter and cheaper yet still highly functional compared to their off-the-shelf counterparts—for example, lightweight and stiff mounts, shielding against stray laser light, or flexible elements allowing fine mechanical adjustments. Simulations of the deformations are included to compare the printed and metal versions. The article ends with a summary of the benefits and limitations of using 3D-printed composites in optomechanics. Full article

Orbital floor fractures are primarily caused by blunt trauma to the area around the eyes. These injuries most commonly affect the orbital floor and medial wall due to the fragility of these structures. The mechanism typically involves transmission of force through the orbital rim or an acute increase in intraorbital pressure caused by globe displacement. Blowout fractures often occur alongside additional maxillofacial fractures and periorbital soft tissue injuries. The reported causes mirror those of general maxillofacial trauma and include motor vehicle collisions, interpersonal violence, falls, sports-related injuries, incidents involving firearms, and occupational accidents. Here, we present the case of a 56-year-old male patient who sustained an exceptionally rare injury pattern characterized by a complete orbital floor fracture with globe dislocation into the maxillary sinus. Such extensive fractures are associated with significant functional impairments, including diplopia, enophthalmos, and restricted extraocular muscle movement, as well as marked aesthetic deformity. Comprehensive diagnostic imaging, comprising coronal, sagittal, and three-dimensional CT reconstructions, was crucial for accurately assessing the extent of bony disruption and soft tissue involvement. Particular emphasis should be placed on imaging that clearly delineates the extraocular muscles and the optic nerve, as precise evaluation of these structures is essential for surgical planning and prognosis. Surgical management involved repositioning of the globe and the orbital contents, followed by reconstruction of the orbital floor using a titanium mesh anchored to the infraorbital rim. This case highlights the technical challenges of total orbital floor reconstruction, emphasizing the importance of meticulous anatomical restoration for achieving optimal functional and aesthetic outcomes. Full article

Tensegrity structures, by definition composed of compressed members suspended in a network of tensile cables, are characterised by a high strength-to-weight ratio and the ability to undergo reversible deformations. Their application as cores of sandwich panels represents an innovative approach to lightweight design, enabling the regulation of mechanical properties while reducing material consumption. This study presents a finite element modelling procedure that combines analytical determination of prestress using singular value decomposition with implementation in the ABAQUS™ 2019 software. Geometry generation and prestress definitions were automated with Python 3 scripts, while algebraic analysis of individual modules was performed in Wolfram Mathematica. Two models were investigated: M1, composed of four identical modules, and M2, composed of four modules arranged in two mirrored pairs. Model M1 exhibited a linear elastic response with a constant global stiffness of 13.9 kN/mm, stable regardless of the prestress level. Model M2 showed nonlinear hardening behaviour with variable stiffness ranging from 0.135 to 1.1 kN/mm and required prestress to ensure static stability. Eigenvalue analysis confirmed the full stability of M1 and the increase in stability of M2 upon the introduction of prestress. The proposed method enables precise control of prestress distribution, which is crucial for the stability and stiffness of tensegrity structures. The M2 configuration, due to its sensitivity to prestress and variable stiffness, is particularly promising as an adaptive sandwich panel core in morphing structures, adaptive building systems, and deployable constructions. Full article

The detection and characterization of exoplanets are central topics in astronomy, and high-contrast imaging techniques such nulling interferometry, coronagraphs, and extreme adaptive optics (ExAO) are key tools for the direct detection of exoplanets. This review synthesizes the pivotal role of these techniques in astronomical research and critically analyzes their role as key drivers of progress in the field. Nulling interferometry suppresses stellar light through the phase control of multiple telescopes, thereby enhancing the detection of faint planetary signals. This technology has evolved from the initial Bracewell concept to the LIFE (Large Interferometer For Exoplanets) technique, which will achieve a contrast ratio of 10⁻⁷ in the mid-infrared wavelength range in the future. Coronagraphs block starlight to create a “dark region” for direct observation of exoplanets. By leveraging innovative mask designs, theoretical contrast ratios of up to 4 × 10⁻⁹ can be achieved. ExAO systems achieve precise wavefront correction to optimize the high-contrast imaging performance and mitigate atmospheric disturbances. By leveraging wavefront sensing, thousand-element deformable mirrors, and real-time control algorithms, these systems suppress the turbulence correction residuals to 80 nm RMS, enabling ground-based telescopes to achieve a Strehl ratio exceeding 0.9. This work provides a comprehensive analysis of the underlying principles, prevailing challenges, and future application prospects of these technologies in astronomy. Full article