Complex Shapes Research Articles

A novel framework for low-contrast and random multi-scale blade casting defect detection by an adaptive global dynamic detection transformer

The radiographic inspection plays a crucial role in ensuring the casting quality for improving the service life under harsh environments. However, due to the low-contrast between the defects and the image background, the random spatial position distribution, random shapes and aspect ratios of the defects, the development of an accurate defect automatic detection system is still challenging. To address these issues, this paper proposes a novel framework for low-contrast and random multi-scale casting defect detection, which is referred to as adaptive global dynamic detection transformer (AGD-DETR). A novel defect-aware data augmentation method is first proposed to adaptively highlight the feature of the low-contrast defect boundary. A multi-attentional pyramid feature refinement (MPFR) module is then established to refine and fuse the multi-scale defect features of random sizes. Afterwards, a novel global dynamic receptive fusion-transformer (GDRF-Transformer) detection scheme is designed to perform the global perception and feature dynamic extraction of complex internal casting defects. It includes 4D-anchor query and cross-layer box update strategy, query rectification by prior information of defect aspect ratio, and global adaptive-feed forward network (GA-FFN). A dataset comprising turbine blade casting defect radiographic (TBCDR) images, is used to demonstrate the high efficiency of the proposed AGD-DETR. The obtained results show that the proposed method can accurately capture the spatial position distributions and complex defect shapes. Furthermore, it outperforms existing state-of-the-art defect detection methods.

Induction heating simulation for aircraft RTM toolings

Aircraft CFRP parts as sharklets are produced in resin transfer molding (RTM) tooling. The parts need to be heated up homogenously over the whole area with a constant temperature. The complex shape and accessibility of the tooling make it hard to introduce a common heating system. In addition, the heat must be transferred through the Invar metal tooling structure onto the CFRP. Infrared lamp, air fan and microwave heating are concepts in development. Electrical heating layer mats and cages are laborious in applying. Induction has the advantage of contact-less, efficient, and fast heating. Induction heating was tested for the structural bonding of CFRP frames and stringers showing high bonding strengths. To apply this technology for the RTM tooling, the placement and distance of the induction coils is important. Simulation can help to find the right adjustments and power needed for induction heating. With the program COMSOL the surface and the coils are modeled, and the numerically structured net is divided in small tetrahedron and quadratic sub elements. Since there is no magnetic streamline in the middle of the coil-section, a symmetric halving of the structure is applied as a boundary condition. The temperature-time development and the distance of the coils are simulated in 2D and 3D. Due to the material properties of the magnetic flux concentrator (MFC), higher flux concentration of the magnetic field occurred only in 2D. The results are validated by experiments and are in good agreement.

A new corrective method for the Tanzer’s group IIB constricted ear: Helical expansion using V-Y advancement flap combined with concha cartilage graft

BackgroundThe complexity of the constricted ear's shape renders a uniform surgical method unattainable, thus posing an ongoing challenge in its correction. The Tanzer’s group IIB constricted ear is characterized by a prominent downward folding, an underdeveloped antihelix, and the absence of sacpha. The present study utilized a V-Y advancement flap combined with concha cartilage for the repair of Tanzer’s group IIB constricted ear. MethodFrom September 2016 to September 2022, a total of 16 patients diagnosed with type IIB ear constriction were enrolled in this retrospective study. The correction procedure for constricted ear involved the utilization of a V-Y advancement flap combined with concha cartilage graft. The auricle shape data of the patients, as well as their VAS satisfaction score and auricle aesthetic score, were examined both preoperatively and 12 months postoperatively. ResultThe mean duration of follow-up in this study was 18 months. The postoperative measurements of ear length, ear width, bilateral differences in ear length, and bilateral differences in ear width exhibited significant improvement compared to preoperative values. The mean preoperative AOS score was 1.12±0.34, while the mean postoperative AOS score increased to 3.81±0.40. The preoperative VAS satisfaction score was recorded as 2.31±0.70, while the postoperative VAS score significantly increased to 8.00±0.89. The follow-up period did not present any cases of flap necrosis, hematoma, infection, or wound dehiscence. ConclusionThe combination of V-Y advancement flap and concha cartilage transplantation for the correction of Tanzer’s group IIB constricted ear can achieve a natural and aesthetically pleasing auricle shape, resulting in high patient satisfaction.

Convergent direct and indirect cortical streams shape avoidance decisions in mice via the midline thalamus

Current concepts of corticothalamic organization in the mammalian brain are mainly based on sensory systems, with less focus on circuits for higher-order cognitive functions. In sensory systems, first-order thalamic relays are driven by subcortical inputs and modulated by cortical feedback, while higher-order relays receive strong excitatory cortical inputs. The applicability of these principles beyond sensory systems is uncertain. We investigated mouse prefronto-thalamic projections to the midline thalamus, revealing distinct top-down control. Unlike sensory systems, this pathway relies on indirect modulation via the thalamic reticular nucleus (TRN). Specifically, the prelimbic area, which influences emotional and motivated behaviors, impacts instrumental avoidance responses through direct and indirect projections to the paraventricular thalamus. Both pathways promote defensive states, but the indirect pathway via the TRN is essential for organizing avoidance decisions through disinhibition. Our findings highlight intra-thalamic circuit dynamics that integrate cortical cognitive signals and their role in shaping complex behaviors.

Study on flexural and self-repairing properties of shape memory alloy concrete beams

The generation and expansion of cracks in concrete materials have always been a problem that needs to be solved, and an increasing number of scholars are beginning to hope that structures will have bionic functions of self-diagnosis and self-repairing of damage. In this study, shape memory alloy (SMA) concrete beams are prepared. The flexural and self-repairing properties of SMA concrete beams were investigated by a four-point bending test. The effects of various factors on the bearing capacity, ductility, and crack width before and after repair were analyzed. The experimental results indicate that the increase of SMA fiber content and the complexity of the SMA bar end shape can significantly enhance the flexural bearing capacity and repair performance of the beam. The increase in the bond length of SMA bars can enhance the bending resistance of the beam, but it will reduce its self-repairing performance. The repair rate of SMA on concrete cracks is 45.7 %-76.5 %, and the load recovery rate is between 49.4 % and 80.6 %. The flexural load capacity calculation formula is proposed, and the calculation results closely match the test values, providing a reference for the application of SMA.

Patient-specific 3D-printed Splint for Mallet Finger Injury.

Despite the frequency of mallet finger injuries, treatment options can often be costly, time-consuming, and ill-fitted. Three-dimensional (3D) printing allows for the production of highly customized and inexpensive splints, which suggests potential efficacy in the prescription of casts for musculoskeletal injuries. This study explores how the use of engineering concepts such as 3D printing and topology optimization (TO) can improve outcomes for patients. 3D printing enables the direct fabrication of the patient-specific complex shapes while utilizing finite element analysis and TO in the design of the splint allowed for the most efficient distribution of material to achieve mechanical requirements while reducing the amount of material used. The reduction in used material leads to significant improvements in weight reduction and heat dissipation, which would improve breathability and less sweating for the patient, greatly increasing comfort for the duration of their recovery.

A way to control sintering deformation of Al2O3 components by gradient shrinkage

Sintering deformation is a great hindrance to the development of ceramic components with complex shapes. In this work, single-face coating method has been used to prepare the special shaped Al2O3 components by taking advantage of the difference in shrinkage between substrate and coating. By adjusting the content of SiO2 in the coating material which consisted of SiO2 and Al2O3 powder, the sintering deformation of Al2O3 ceramics coated with the above material would be controlled during the sintering process. The sintering behavior of Al2O3 green body with and without single-face coating were studied through visual in-situ tests combined with photographing technology. By comparing the images of specimens under different sintering temperatures (defined this method as the image relative method), the warped deformation and the shrinkage behavior of the above specimens were discussed. Moreover, the relationship between curvature radius and shrinkage rate was deduced. Results indicate that, due to the discrepancy in shrinkage of substrate and coating, the deformation of samples occurred in the heating process. And the shrinkage, the elasticity modulus and the ratio of the sectional coating area to substrate area play a major role in determining the shape of ceramics. The way to fabricate the shape controlled ceramic components by the gradient shrinkage is a novel and effective method, which can be used for the plate and shell products with complex shapes.

Voxel-based evolutionary topological optimization of connected structures for natural frequency optimization

AbstractThe topology optimization methodology is widely utilized in industrial engineering for designing lightweight and efficient components. In this framework, considering natural frequencies is crucial for adequately designing components and structures exposed to dynamic loads, as in aerospace or automotive applications. The scientific community has shown the efficiency of Bi-directional Evolutionary Structural Optimization (BESO), showcasing its ability to converge towards optimal solid-void or bi-material solutions for a wide range of frequency optimization problems in continuum structures. However, these methods show limits when the complexity of the domain volume increases; thus, they are well-suited for academic case studies but may fail when dealing with industrial applications that require more complex shapes. The connectivity of the structures resulting from the optimization also plays a fundamental role in choosing the best optimization approach, as some available commercial and open-source codes nowadays return unfeasible sparse structures. An improved voxel-based BESO algorithm has been developed in this work to cope with current limits in lightweight structure optimization. A significant case study has been developed to evaluate the performances of the new methodology and compare it with existing algorithms. In contrast to previous studies, the method we developed guarantees that the final structure respects constraints on the initial design volume and that the structure’s connection is preserved, thus enabling the manufacturing of the component with Additive Manufacturing technologies. The proposed approach can be complemented by smoothing algorithms to obtain a structure with externally appealing surfaces.

Management of frontal sinus and frontal recess inverted papilloma: our experience and systematic review.

For frontal sinus inverted papilloma (FSIP) management, an endoscopic endonasal approach (EEA) can be combined (or not) with an external approach by an osteoplastic flap (OPF) or with a more conservative open approach. The present study aims to describe our experience in the management of FSIP, focusing on disease-related and anatomical features influencing outcomes and recurrence. This case series of FSIP investigated anatomical and disease-related predictors of recurrence associated with EEA or a combined EEA-OPF approach. A systematic review was also performed, selecting publications on IP with the insertion point in the frontal sinus or frontal recess. Among 30 patients included, 18 underwent EEA, while 12 received a combined EEA-OPF approach. During a median follow-up of 37 months, the frontal sinus was cleared of IP in all cases except 2 in the EEA group, who presented a complex posterior wall shape of the frontal sinus. From the systematic review, a combined EEA-OPF approach was associated with a lower risk of recurrence. A correct indication for a combined EEA-OPF approach is paramount and should integrate all disease-related and anatomical features, including posterior wall shape.

Design of a Robotic 3D Printing System

Abstract Additive manufacturing enables the production of complex shapes with a large degree of freedom compared to conventional manufacturing techniques such as injection molding, thermoforming or pressing. In particular, the creation of moving parts, complex structures and large-scale printing remains underexplored and research is constantly expanding. Due to design limitations related to the construction of currently available printers, 3D printing technology is increasingly being combined with robotics. Using a robot to 3D print products eliminates the need to design complex printer structures, which ultimately should simplify the process of manufacturing large-scale products and shorten the time required for preparation and production. The paper deals with the description of the designed 3D printing system and the procedure of the steps of creating a robotic simulation model with the generation of a control program for the FDM 3D printing process by an industrial robot.

Effects of Preheating on the Microstructure of Laser-DED AISI 420

AISI 420 stainless steel (420 SS) is a martensitic type known for its high strength and abrasion resistance, and it is extensively used in hard-facing applications (Refs. 1, 2). However, Type 420 SS contains untempered martensite in the as-welded condition and is generally considered to have poor weldability. Successful arc welding of 420 SS requires proper preheating, post-weld heat treatment, and strict adherence to low hydrogen practices. Direct energy deposition (DED) is a fusion-based additive manufacturing (AM) process that melts metal powders to produce complex shapes and can be used for surfacing or hard-facing operations. However, as small-volume AM deposits undergo self-quenching, the cooling rate can be much faster than in welding. Consequently, the phase transformations in the AM deposit deviate further from equilibrium relative to traditional welding processes, resulting in heterogeneous microstructures and mechanical properties, potentially limiting the direct use of AM components without post-AM heat treatment (Ref. 3). Our prior work with laser-DED (L-DED) hard-facing 420 SS powder without preheat combined experiments, characterization, and kinetic modeling to rationalize the presence of remnant δ-ferrite and austenite quantitatively in room temperature microstructures. This study aimed to quantify the effects of preheating above the Ms temperature on the extent of solidification segregation and microstructures for a wall build for L-DED processing of the same heat of 420 powder. The results of the current work are contrasted with our prior study, which allows for a greater understanding of L-DED opportunities with 420 SS.

Expediency of Electric Arc Milling in Complex Shaping of Aircraft Engine Components

Expediency of Electric Arc Milling in Complex Shaping of Aircraft Engine Components

Challenges in characterizing additively manufactured AlSi10Mg using X-ray Laue micro-beam diffraction

Abstract Additive manufacturing of metals using for example laser powder bed fusion systems generally results in grains of complex shapes with cellular structure of submicron sizes, accompanied by a high dislocation density. This paper presents preliminary results from characterizing an AlSi10Mg alloy manufactured by L-PBF using non-destructive three-dimensional X-ray Laue micro-beam diffraction. Both synchrotron and laboratory X-ray methods are used. The aim is to identify challenges in characterizing these microstructural features and to propose future research directions to address them.

Optical configurations for applying antireflective nanotexture on spherical lenses by ultrashort laser structuring

This paper focuses on minimizing the optical reflection on spherical fused silica lenses using femtosecond (fs) laser nanostructuring. A unique type of nanopillar formation has been observed on SiO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extrm{SiO}_2$$\\end{document} surfaces possessing antireflective properties when irradiated with a specific number of overlapping pulses, polarization, and fluence levels. Maintaining precise control over these sensitive technological parameters such as defocus and incident angle during the processing of geometrically complex shapes presents a significant challenge. This study proposes a theoretical optical arrangement to address this limitation by the design of a custom scanner system optimized for curved surfaces. The paper details the optimization process of such a bent image space (inverse-hypercentric) optical system using Zemax OpticStudio. Although the practical realization of the arrangement has not been performed, simulations are conducted to prove the functionality of the concept. Furthermore, we propose a practical method for segmented structuring of spherical surfaces based on consecutive repositioning and irradiation using an industrial robotic arm. By constructing the optical model, the necessary resolution of the segmentation has been calculated for a typical F-Theta scanner system and experimental verification has been performed.

The Systemic Genotype-Phenotype Characterization of PAX6-Related Eye Disease in 164 Chinese Families.

This study aims to evaluate the genetic and phenotypic characteristics and elucidate the genotype-phenotype correlations of a large Chinese cohort with PAX6-related disorders. Variants detected with exome sequencing were filtered through multistep bioinformatic and co-segregation analyses, and validated by Sanger sequencing. The related clinical data were collected, and cluster analysis and statistical analysis of the PAX6-related phenotypes across different variant groups were carried out. Parental mosaicism was investigated using cloning analysis and Droplet digital PCR. A total of 119 pathogenic or likely pathogenic PAX6 variants, including 74 truncation, 31 missense, and 14 others, were identified in 228 patients from 164 unrelated families. The most common phenotypes were foveal hypoplasia (97.8%), nystagmus (92.6%), aniridia (76.7%), cataract (36.8%), and iris hypoplasia (22.4%). Mosaicism ranging from 13.9% to 18.8% was identified in 3 unrelated patients' parents with relatively mild phenotypes. Missense variants in the linker region of the paired domain were associated with high myopia, whereas truncation variants in the homeodomain and proline-serine-threonine-rich domain were associated with hyperopia. Similarly, the degree of iris defects, visual acuity, and associated ocular comorbidity varied among the different types and locations of PAX6 variants. Our data indicate that foveal hypoplasia but not aniridia is the most common sign of PAX6-related disorders, contributing to subtle iris changes that might easily be overlooked in clinical practice. Recognition of mosaicism in atypical cases or parents with very mild phenotypes is important in genetic counseling as their offspring are at increased risk of typical aniridia. Recognition of the genotype-phenotype relationship emphasizes involvement of PAX6 regulation in shaping complex ocular phenotypes.

Co-scale cross-attentional transformer for rearrangement target detection

Rearranging objects (e.g. vase, door) back in their original positions is one of the most fundamental skills for domestic service robots (DSRs). In rearrangement tasks, it is crucial to detect the objects that need to be rearranged according to the goal and current states. In this study, we focus on Rearrangement Target Detection (RTD), where the model generates a change mask for objects that should be rearranged. Although many studies have been conducted in the field of Scene Change Detection (SCD), most SCD methods often fail to segment objects with complex shapes and fail to detect the change in the angle of objects that can be opened or closed. In this study, we propose a Co-Scale Cross-Attentional Transformer for RTD. We introduce the Serial Encoder which consists of a sequence of serial blocks and the Cross-Attentional Encoder which models the relationship between the goal and current states. We built a new dataset consisting of RGB images and change masks regarding the goal and current states. We validated our method on the dataset and the results demonstrated that our method outperformed baseline methods on F 1 -score and mean IoU.

Mechanically Robust Biopolymer Optical Fibers with Enhanced Performance in the Near-Infrared Region.

Polymer optical fibers (POFs) are lightweight, fatigue-tolerant, and suitable for local area networks, automobiles, aerospace, smart textiles, supercomputers, and servers. However, commercially available POFs are exclusively fabricated using synthetic polymers derived from nonrenewable resources. Recently, attempts have been made to fabricate biocompatible and biopolymeric optical fibers. However, their limitations in mechanical performance, thermal stability, and optical properties foil practical applications in waveguiding. Here, we report a comprehensive study of the preparation of biopolymer optical fibers with tailored mechanical strength, thermal properties, and their short-distance applications. Specifically, we use alginate as one of the key components with methylcelluloses to promote readily scalable wet spinning at ambient conditions to fabricate 21 combinations of composite fibers. The fibers display high maximum strain (up to 58%), Young's modulus (up to 11 GPa), modulus of toughness (up to 63 MJ/m3), and a high strength (up to 195 MPa), depending on the composition and fabrication conditions. The modulus of toughness is comparable to that of glass optical fibers, while the maximum strain is nearly 15 times higher. The mechanically robust fibers with high thermal stability allow rapid humidity, touch sensing, and complex shapes such as serpentine, coil, or twisted structures without losing their light transmission properties. More importantly, the fibers display enhanced optical performance and sensitivity in the near-infrared (NIR) region, making them suitable for advanced biomedical applications. Our work suggests that biobased materials offer innovative solutions to create short-distance optical fibers from fossil fuel-free resources with novel functionalities.

Binary segmentation of relief patterns on point clouds

Analysis of 3D textures, also known as relief patterns is a challenging task that requires separating repetitive surface patterns from the underlying global geometry. Existing works classify entire surfaces based on one or a few patterns by extracting ad-hoc statistical properties. Unfortunately, these methods are not suitable for objects with multiple geometric textures and perform poorly on more complex shapes. In this paper, we propose a neural network for binary segmentation to infer per-point labels based on the presence of surface relief patterns. We evaluated the proposed architecture on a high resolution point cloud dataset, surpassing the state-of-the-art, while maintaining memory and computation efficiency.

Cut‐Cell Microstructures for Two‐scale Structural Optimization

AbstractTwo‐scale topology optimization, combined with the design of microstructure families with a broad range of effective material parameters, is widely used in many fabrication applications to achieve a target deformation behavior for a variety of objects. The main idea of this approach is to optimize the distribution of material properties in the object partitioned into relatively coarse cells, and then replace each cell with microstructure geometry that mimics these material properties. In this paper, we focus on adapting this approach to complex shapes in situations when preserving the shape's surface is essential.Our approach extends any regular (i.e. defined on a regular lattice grid) microstructure family to complex shapes, by enriching it with tiles adapted to the geometry of the cut‐cell. We propose a fully automated and robust pipeline based on this approach, and we show that the performance of the regular microstructure family is only minimally affected by our extension while allowing its use on 2D and 3D shapes of high complexity.

Gut Microbiome-Driven metabolites influence skin pigmentation in TYRP1 mutant Oujiang Color Common Carp

The gut microbiome plays a key role in regulating the gut-skin axis, and host genetics partially influence this regulation. The study investigated the role of gut microbiota and host genetics in the gut-skin axis, focusing on the unusual “coffee-like” color phenotype observed in TYRP1 mutant Oujiang Color Common Carp. We employed comparative high-throughput omics data from wild-type and mutant fish to quantify the influence of both genetics and gut microbes on skin transcriptomic expression and blood metabolites. We found 525 differential metabolites (DMs) and 45 distinct gut microbial genera in TYRP1 mutant fish compared to wild type. Interaction and causal mediation analyses revealed a complex interplay. The TYRP1 mutation likely triggers an inflammatory pathway involving Acinetobacter bacteria, Leukotrience-C4 and Spermine. This inflammatory response appears to be counterbalanced by an anti-inflammatory cardiovascular genetic network. The net effect is the upregulation of COMT, PLG, C2, C3, F10, TDO2, MHC1, and SERPINF2, leading to unusual coffee-like coloration. This study highlights the intricate interplay between gut microbiota, host genetics, and metabolic pathways in shaping complex phenotypes.