Search

This paper presents an advanced workflow for processing radar imagery stacks using Persistent Scatterer and Distributed Scatterer Interferometry (PSDS) to enhance spatial coherence and improve displacement detection accuracy. The workflow leverages Level 2 Coregistered Single Look Complex (L2-CSLC) images generated by the open-source COMPASS (Coregistered Multi-temporal Sar SLC) framework in combination with the Combined eigenvalue maximum likelihood Phase Linking (CPL) approach implemented in MiaplPy. Starting the analysis directly from Level 2 products offers a significant advantage to end-users, as they simplify processing by being pre-geocoded and ready for immediate analysis. Additionally, the open-source nature of the workflow and the use of L2-CSLC products simplify the processing pipeline, making it easier to distribute directly to users for practical applications in monitoring infrastructure stability in dynamic environments. The ISCE3-MiaplPy workflow is compared against ISCE2-MiaplPy and the European Ground Motion Service (EGMS) to assess its performance in detecting infrastructure deformations in dynamic environments, such as the Algeciras port. The results indicate that ISCE3-MiaplPy delivers denser measurements, albeit with increased noise, compared to its counterparts. This higher resolution enables a more detailed understanding of infrastructure stability and surface dynamics, which is critical for environments with ongoing human activity or natural forces. [ABSTRACT FROM AUTHOR]

On-orbit geometric calibration is key to improving the geometric positioning accuracy of high-resolution optical remote sensing satellite data. Grouped calibration with geometric consistency (GCGC) is proposed in this paper for the Jilin1-KF01B satellite, which is the world's first satellite capable of providing 150-km swath width and 0.5-m resolution data. To ensure the geometric accuracy of high-resolution image data, the GCGC method conducts grouped calibration of the time delay integration charge-coupled device (TDI CCD). Each group independently calibrates the exterior orientation elements to address the multi-time synchronization issues between imaging processing system (IPS). An additional inter-chip geometric positioning consistency constraint is used to enhance geometric positioning consistency in the overlapping areas between adjacent CCDs. By combining image simulation techniques associated with spectral bands, the calibrated panchromatic data are used to generate simulated multispectral reference band image as control data, thereby enhancing the geometric alignment consistency between panchromatic and multispectral data. Experimental results show that the average seamless stitching accuracy of the basic products after calibration is better than 0.6 pixels, the positioning accuracy without ground control points(GCPs) is better than 20 m, the band-to-band registration accuracy is better than 0.3 pixels, the average geometric alignment consistency between panchromatic and multispectral data are better than 0.25 multispectral pixels, the geometric accuracy with GCPs is better than 2.1 m, and the geometric alignment consistency accuracy of multi-temporal data are better than 2 m. The GCGC method significantly improves the quality of image data from the Jilin1-KF01B satellite and provide important references and practical experience for the geometric calibration of other large-swath high-resolution remote sensing satellites. [ABSTRACT FROM AUTHOR]

We present a novel, systematic method for evaluating design printability in 3D food printing using a scoring system based on the Design for Additive Manufacturing (DfAM) guidelines. This study addresses a gap in the current literature by proposing a structured approach to assess and enhance the printability of 3D food designs. Our framework consists of a set of nine critical questions derived from the multi-level DfAM guidelines, focusing on key printability factors including unsupported features, geometric accuracy, and surface finish. The evaluation process converts qualitative assessments into numerical values, resulting in a comprehensive printability score that categorizes designs into high, moderate, or low printability levels. To validate the effectiveness of this method, we conducted a case study involving five different designs. The scoring system successfully explores the design space and maximizes the printability of 3D food products. This method alleviates the challenges in design evaluation compared with traditional trial-and-error approaches. The results demonstrate the practicality and efficiency of our framework's output. The proposed methodology provides a structured approach to design evaluation, offering practical insights and a valuable tool for improving the success rate of 3D printed food products. This research contributes to the field by offering a systematic framework for assessing and enhancing the printability of 3D food designs, potentially accelerating the adoption and effectiveness of 3D food printing technology in various applications. [ABSTRACT FROM AUTHOR]

The present study investigates the impact of different heat transfer approaches on the precision of geometry and solidification behavior in additively manufactured thin clad walls. Employing a 2D laser scanner to assess dimensional accuracy, the study demonstrates that thin clad walls produced on a copper base plate with forced air convection exhibit notably superior accuracy compared to those on a mild steel substrate with natural convection. Microstructure analysis unveils distinct characteristics: Thin clad walls printed with natural convection on mild steel display a coarse columnar dendritic structure marked by increasing primary dendrite arm spacing (PDAS) from bottom to top (10.4 ± 0.7 to 14.5 ± 3 µm). In contrast, forced convection leads to a fine cellular and columnar dendritic microstructure with minor PDAS variation (4.6 ± 0.9 to 7.4 ± 1.7 µm) along the entire vertical span. [ABSTRACT FROM AUTHOR]

The article presents an analysis of the geometric accuracy of wax models produced using PolyJet molds. Photopolymer resin was used to make the molds, and the surface of the model was finished in a gloss mode in the 3D printing process. This allows you to obtain a smooth surface of the molded part model. The geometric accuracy of the models was determined by measurements with the GOM ATOS scanner and analysis of the measurement results in relation to the base model made in the 3D-CAD program. Accuracy analysis was the basis for determining the wear of the mold wear when making subsequent models. [ABSTRACT FROM AUTHOR]

Laser-based metal powder bed fusion (PBF-LB/M) offers great potential for producing complex and filigree sub-millimetre parts with customised shapes, such as patient-specific vascular stents. However, stent fabrication via PBF-LB/M encounters fundamental challenges, including dimensional limitations, poor surface quality, difficult support structure handling and geometrical deviations. This study addresses these challenges by investigating the potential and limitations of a novel hybrid post-processing approach. This technique uses the combination of electrochemical polishing and chemical etching and is investigated from process and design perspectives, to emphasise the interactions between the two. With the systematic application of hybrid post-processing, the strut thickness and the surface roughness were substantially reduced. Moreover, it enabled the successful removal of part-internal support structures. Furthermore, angle and orientation-dependent geometrical deviations could be compensated, highlighting the potential of achieving homogenous strut thicknesses within parts containing variable overhang angles. This study demonstrates that the usage of hybrid (electro)chemical post-processing methods with specifically tailored process parameters is a promising approach for overcoming the design- and process-related challenges in PBF-LB/M manufactured sub-millimetre parts. [ABSTRACT FROM AUTHOR]

Nowadays, a wide variety of software for 3D reconstruction from CT scans is available; they differ for costs, capabilities, a priori knowledge, and, it is not trivial to identify the most suitable one for specific purposes. The article is aimed to provide some more information, having set up various metrics for the evaluation of different software's performance. Metrics include software usability, segmentation quality, geometric accuracy, mesh properties and Dice Similarity Coefficient (DSC). Five different software have been considered (Mimics, D2P, Blue Sky Plan, Relu, and 3D Slicer) and tested on four cases; the mandibular bone was used as a benchmark. Relu software, being based on AI, was able to solve some very intricate geometry and proved to have a very good usability. On the other side, the time required for segmentation was significantly higher than other software (reaching over twice the time required by Mimics). Geometric distances between nodes position calculated by different software usually kept below 2.5 mm, reaching 3.1 mm in some very critical area; 75th percentile q 75 is generally less than 0.5 mm, with a maximum of 1.11 mm. Dealing with consistency among software, the maximum DSC value was observed between Mimics and Slicer, D2P and Mimics, and D2P and Slicer, reaching 0.96. This work has demonstrated how mandible segmentation performance among software was generally very good. Nonetheless, differences in geometric accuracy, usability, costs and times required can be significant so that information here provided can be useful to perform an informed choice. • Various commercial and open-source software for image segmentation are available. • Segmentation performances are crucial to choose the proper software. • Relevant metrics are usability, time required, mesh quality, and geometric accuracy. • The consistency among various software results can be measured through DSC. • Accuracy, usability, costs and times can be significantly different among software. [ABSTRACT FROM AUTHOR]

The methodology of experiments and construction of a model for controlling the geometric accuracy indicators of forgings of massive parts of complex shapes is considered on the basis of an experimental study of the wear of ball end mills when processing samples from die material. The resulting models are used to adjust the tool path. [ABSTRACT FROM AUTHOR]

The object of this study is the technological preparation of the production of a light aircraft wing using reverse engineering technology. The subject of research is a quality indicator–the geometric accuracy of manufacturing the convex-concave parts of aerospace technology. Calculations of geometric accuracy were performed for the program-instrumental method of co-ordination. As the experimental part it was taken the worn out wing tip of a light aircraft. The following results were obtained. An approach for specifying the aerodynamic airfoil and cross sections of the wing tip when constructing its digital model has been proposed. A 3D scanning of the wing tip with the formation of a digital portrait in STL format, as well as its refinement into a STEP format, using organic and mechanical methods, was accomplished. A digital mock-up of the wing tip was built taking into account the geometry of the aerodynamic airfoil in cross sections as well as a digital mock-up of the form (mould) for its manufacture according to the polygonal model, which was created by the organic method due to it had the highest dimensional accuracy. It was determined that the maximum deviation of the actual wing contour from the theoretical one was as follows: the upper deviation was 0.84 mm, the lower deviation was –0.65 mm. The maximum deviation of the actual wing contour from the theoretical one was ±0.3 mm. The expected (calculated) errors did not exceed the specified value of the tolerance on the wing outer contour that equal to ±1.0 mm, thus, the adopted method of assembling the wing under the conditions of co-ordination by the program-instrumental method ensured the specified geometric accuracy. The results of experimental studies confirmed the adequacy of the proposed approach for determining the aerodynamic airfoil of the cross-sections of the digital mock-up of convex-concave parts for aerospace technology during their technological preparation for production with the use of reverse engineering. [ABSTRACT FROM AUTHOR]

The object of this paper is the geometric accuracy of the acquired portrait from the 3D printed full-scale sample in the reduced size of the convex-concave parts compared to the correspondingly reduced ideal one. The subject of research is reverse engineering and additive technology for manufacturing convex-concave parts for mechanical engineering (ME). A new prototyping methodology for convex-concave parts of mechanical engineering objects has proposed. Underlying the methodology is the use of the scaled (by reducing in size) ideal portrait of the 3D scanned original part. The decision to start the production is made by comparing the geometry of the portrait acquired from the 3D printed sample in reduced size with the ideal one, provided that the values are within the tolerance range. The following results were obtained. A design and technological analysis of the blade of the pumped hydroelectric power station was performed, after which a 3D scanner and a 3D printer were selected. A 3D scan of the blade with the formation of a portrait in the STL format file was implemented, as well as its refinement into an ideal one. From the geometric features and shapes of the blade, as well as the technical characteristics of the 3D printer, the percentage of reducing the sample for printing (by 75 % of the original dimensions) was calculated. According to the rated dimensions of the original part and the reduced sample, the tolerance field was set for the size: 0.6 mm and 0.25 mm, respectively, at 12 quality of the part’s manufacturing accuracy. Inspection of the printed sample and comparison with the correspondingly reduced ideal portrait revealed a deviation from –0.123 to +0.120 mm, which is within the defined tolerance field for the manufactured reduced sample. The results of experimental studies confirmed the adequacy of the proposed methodology for prototyping the mechanical engineering parts and verified the theoretical foundations of reverse engineering for convex-concave parts of any large size by using a proportional reduction in the size of finished portraits [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) of load‐bearing metal implants allows sustainable production of personalized implants with complex shapes and inner architectures. Implants must meet strict requirements to not harm patients, and production technique must certify their performance. Available materials, many production parameters and implant personalization on patient's needs represent limits of AM. Layer‐by‐layer material deposition and repeated thermal cycles typical of AM may also cause discontinuities between layers affecting implant mechanical features, and its match to the host body. In this paper the mechanical challenges that AM must overcome to replace traditional manufacturing techniques are discussed, in order to better understand whether AM has to be limited to implant personalization for exceptional cases. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Remote Sensing is the property of Editorial Office of Journal of Remote Sensing & Science Publishing Co. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article presents an analysis of the geometric accuracy of wax models produced using PolyJet molds. Photopolymer resin was used to make the molds, and the surface of the model was finished in a gloss mode in the 3D printing process. This allows you to obtain a smooth surface of the molded part model. The geometric accuracy of the models was determined by measurements with the GOM ATOS scanner and analysis of the measurement results in relation to the base model made in the 3D-CAD program. Accuracy analysis was the basis for determining the wear of the mold wear when making subsequent models.

This paper presents an advanced workflow for processing radar imagery stacks using Persistent Scatterer and Distributed Scatterer Interferometry (PSDS) to enhance spatial coherence and improve displacement detection accuracy. The workflow leverages Level 2 Coregistered Single Look Complex (L2-CSLC) images generated by the open-source COMPASS (Coregistered Multi-temporal Sar SLC) framework in combination with the Combined eigenvalue maximum likelihood Phase Linking (CPL) approach implemented in MiaplPy. Starting the analysis directly from Level 2 products offers a significant advantage to end-users, as they simplify processing by being pre-geocoded and ready for immediate analysis. Additionally, the open-source nature of the workflow and the use of L2-CSLC products simplify the processing pipeline, making it easier to distribute directly to users for practical applications in monitoring infrastructure stability in dynamic environments. The ISCE3-MiaplPy workflow is compared against ISCE2-MiaplPy and the European Ground Motion Service (EGMS) to assess its performance in detecting infrastructure deformations in dynamic environments, such as the Algeciras port. The results indicate that ISCE3-MiaplPy delivers denser measurements, albeit with increased noise, compared to its counterparts. This higher resolution enables a more detailed understanding of infrastructure stability and surface dynamics, which is critical for environments with ongoing human activity or natural forces.

On-orbit geometric calibration is key to improving the geometric positioning accuracy of high-resolution optical remote sensing satellite data. Grouped calibration with geometric consistency (GCGC) is proposed in this paper for the Jilin1-KF01B satellite, which is the world’s first satellite capable of providing 150-km swath width and 0.5-m resolution data. To ensure the geometric accuracy of high-resolution image data, the GCGC method conducts grouped calibration of the time delay integration charge-coupled device (TDI CCD). Each group independently calibrates the exterior orientation elements to address the multi-time synchronization issues between imaging processing system (IPS). An additional inter-chip geometric positioning consistency constraint is used to enhance geometric positioning consistency in the overlapping areas between adjacent CCDs. By combining image simulation techniques associated with spectral bands, the calibrated panchromatic data are used to generate simulated multispectral reference band image as control data, thereby enhancing the geometric alignment consistency between panchromatic and multispectral data. Experimental results show that the average seamless stitching accuracy of the basic products after calibration is better than 0.6 pixels, the positioning accuracy without ground control points(GCPs) is better than 20 m, the band-to-band registration accuracy is better than 0.3 pixels, the average geometric alignment consistency between panchromatic and multispectral data are better than 0.25 multispectral pixels, the geometric accuracy with GCPs is better than 2.1 m, and the geometric alignment consistency accuracy of multi-temporal data are better than 2 m. The GCGC method significantly improves the quality of image data from the Jilin1-KF01B satellite and provide important references and practical experience for the geometric calibration of other large-swath high-resolution remote sensing satellites.

We present a novel, systematic method for evaluating design printability in 3D food printing using a scoring system based on the Design for Additive Manufacturing (DfAM) guidelines. This study addresses a gap in the current literature by proposing a structured approach to assess and enhance the printability of 3D food designs. Our framework consists of a set of nine critical questions derived from the multi-level DfAM guidelines, focusing on key printability factors including unsupported features, geometric accuracy, and surface finish. The evaluation process converts qualitative assessments into numerical values, resulting in a comprehensive printability score that categorizes designs into high, moderate, or low printability levels. To validate the effectiveness of this method, we conducted a case study involving five different designs. The scoring system successfully explores the design space and maximizes the printability of 3D food products. This method alleviates the challenges in design evaluation compared with traditional trial-and-error approaches. The results demonstrate the practicality and efficiency of our framework’s output. The proposed methodology provides a structured approach to design evaluation, offering practical insights and a valuable tool for improving the success rate of 3D printed food products. This research contributes to the field by offering a systematic framework for assessing and enhancing the printability of 3D food designs, potentially accelerating the adoption and effectiveness of 3D food printing technology in various applications.

Aluminium 6061 (Al6061) is a widely used material for various industrial applications due to low density and high strength. Nevertheless, the conventional machining operations are not the best choice for the machining purposes. Therefore, amongst all the non-conventional machining operations, electric discharge machining (EDM) is opted to carry out the research due to its wide ability to cut the materials. But the high electrode wear rate (EWR) and high dimensional inaccuracy or overcut (OC) of EDM limit its usage. Consequently, nanopowder is added to the dielectric medium to address the abovementioned issues. Nanopowder mixed EDM (NPMEDM) process is a complex process in terms of performance predictability for different materials. Similarly, the interactions between the process parameters such as peak current (Ip), spark voltage (Sv), pulse on time (Pon) and powder concentration (Cp) in dielectric enhance the parametric sensitivity. In addition, the cryogenic treatment (CT) of electrodes makes the process complex limiting conventional simulation approaches for modelling inter-relationships. An alternative approach requires experimental exploration and systematic investigation to model EWR and overcutting problems of EDM. Thus, artificial neural networks (ANNs) are used for predictive modelling of the process which are integrated with multi-objective genetic algorithm (MOGA) for parametric optimization. The approach uses experimental data based on response surface methodology (RSM) design of experiments. Moreover, the process physics is thoroughly discussed with parametric effect analysis supported with evidence of microscopic images, scanning electron microscopy (SEM) and 3D surface topographic images. Based on multi-dimensional optimization results, the NT brass electrode showed an improvement of 65.02% in EWR and 59.73% in OC using deionized water. However, CT brass electrode showed 78.41% reduction in EWR and 67.79% improved dimensional accuracy in deionized water. In addition to that, CT brass electrode gave 27.69% less EWR and 81.40% improved OC in deionized water compared to kerosene oil. [ABSTRACT FROM AUTHOR]

Simple Summary: Traumatic brain injuries, a primary global health concern, can lead to severe disabilities. Acute subdural haematoma is one type of traumatic brain injury resulting from the rupture of bridging veins in the brain. Existing numerical models often oversimplify these structures. This study's main goals were to understand how the cerebral vein's cross-sectional shape affects its response, more akin to real-life testing, and to introduce a hyperelastic model for these veins that captures their non-linear behaviour. The results reveal that the vein's shape significantly influences its response to stretching, highlighting the need for more realistic geometries in modelling. Additionally, hyperelastic models, like the Marlow and polynomial models, were successfully implemented. This research provides valuable insights into the mechanical properties of bridging veins and their response to tensile loading, potentially improving our understanding of traumatic brain injuries. Traumatic brain injury (TBI) is a serious global health issue, leading to serious disabilities. One type of TBI is acute subdural haematoma (ASDH), which occurs when a bridging vein ruptures. Many numerical models of these structures, mainly based on the finite element method, have been developed. However, most rely on linear elasticity (without validation) and others on simplifications at the geometrical level. An example of the latter is the assumption of a regular cylinder with a constant radius, or the geometry of the vein acquired from medical images. Unfortunately, these do not replicate the real conditions of a mechanical tensile test. In this work, the main goal is to evaluate the influence of the vein's geometry in its mechanical behaviour under tensile loading, simulating the real conditions of experimental tests. The second goal is to implement a hyperelastic model of the bridging veins where it would be possible to observe its non-linear elastic behaviour. The results of the developed finite element models were compared to experimental data available in the literature and other models. It was possible to conclude that the geometry of the vein structure influences the tensile stress–strain curve, which means that flattened specimens should be modelled when validating constitutive models for bridging veins. Additionally, the implementation of hyperelastic material models has been verified, highlighting the potential application of the Marlow and reduced polynomial (of fourth and sixth orders) constitutive models. [ABSTRACT FROM AUTHOR]

The geometric accuracy and surface quality of thin-film cooling holes have a significant impact on the cooling efficiency and fatigue life of aeroengine turbine blades. In this paper, we conducted experimental research on the processing of nickel-based single-crystal high-temperature alloy DD6 flat plates using different femtosecond laser processes. Our focus was on analyzing the effects of various laser parameters on the geometric accuracy results of microholes and the quality of the surfaces and inner walls of these holes. The results demonstrate that femtosecond laser processing has great influence on the geometrical accuracy and surface quality results of film cooling holes. Notably, the average laser power, focus position, and feed volume exert a significant influence on the geometric accuracy results of microholes. For instance, a higher laser power can damage the microhole wall, thereby leading to the formation of tiny holes and cracks. Additionally, microholes exhibit optimal roundness and taper values when using a zero defocus volume. Moreover, increasing the feed distance results in enhanced entrance and exit roundness, whereas scanning speed has a negligible impact on microhole roundness. [ABSTRACT FROM AUTHOR]

Abstract The application of continuous natural fibers as reinforcement in composite thin-walled structures offers a feasible approach to achieve light weight and high strength while remaining environmentally friendly. In addition, additive manufacturing technology provides a favorable process foundation for its realization. In this study, the printability and energy absorption properties of 3D printed continuous fiber reinforced thin-walled structures with different configurations were investigated. The results suggested that a low printing speed and a proper layer thickness would mitigate the printing defects within the structures. The printing geometry accuracy of the structures could be further improved by rounding the sharp corners with appropriate radii. This study successfully fabricated structures with various configurations characterized by high geometric accuracy through printing parameters optimization and path smoothing. Moreover, the compressive property and energy absorption characteristics of the structures under quasi-static axial compression were evaluated and compared. It was found that all studied thin-walled structures exhibited progressive folding deformation patterns during compression. In particular, energy absorption process was achieved through the combined damage modes of plastic deformation, fiber pullout and delamination. Furthermore, the comparison results showed that the hexagonal structure exhibited the best energy absorption performance. The study revealed the structure-mechanical property relationship of 3D printed continuous fiber reinforced composite thin-walled structures through the analysis of multiscale failure characteristics and load response, which is valuable for broadening their applications.

The application of continuous natural fibers as reinforcement in composite thin-walled structures offers a feasible approach to achieve light weight and high strength while remaining environmentally friendly. In addition, additive manufacturing technology provides a favorable process foundation for its realization. In this study, the printability and energy absorption properties of 3D printed continuous fiber reinforced thin-walled structures with different configurations were investigated. The results suggested that a low printing speed and a proper layer thickness would mitigate the printing defects within the structures. The printing geometry accuracy of the structures could be further improved by rounding the sharp corners with appropriate radii. This study successfully fabricated structures with various configurations characterized by high geometric accuracy through printing parameters optimization and path smoothing. Moreover, the compressive property and energy absorption characteristics of the structures under quasi-static axial compression were evaluated and compared. It was found that all studied thin-walled structures exhibited progressive folding deformation patterns during compression. In particular, energy absorption process was achieved through the combined damage modes of plastic deformation, fiber pullout and delamination. Furthermore, the comparison results showed that the hexagonal structure exhibited the best energy absorption performance. The study revealed the structure-mechanical property relationship of 3D printed continuous fiber reinforced composite thin-walled structures through the analysis of multiscale failure characteristics and load response, which is valuable for broadening their applications. [ABSTRACT FROM AUTHOR]

Achieving the required dimensional and geometrical accuracy as well as the appearance and performance quality in the production of industrial parts and the availability of interchangeability in the assembly and supply of spare parts for products has been one of the important challenges of the industry. In this research, the effect of adding axial ultrasonic vibration to the tool on the geometric accuracy of the Al6061 -T6 work piece in the milling process was investigated. By analyzing the results, it was found that the presence of axial ultrasonic vibration improves the parallelism and flatness of the wall and the smoothness of the bottom surface as well as the perpendicularity of the wall with the bottom. It was also observed that a higher feed speed increases geometric deviations and surface roughness, while a higher cutting speed reduces them. By comparing the graphs, it was found that the positive effect of ultrasonic vibrations on the quality of the surface and the geometric accuracy of the work piece is more noticeable in the conditions of lower cutting speed and higher feed; That is, the condition in which we face the worst surface quality and the lowest geometric accuracy in conventional milling. [ABSTRACT FROM AUTHOR]

The system of Czech technical standards for geometric accuracy assumes that the designer determines the functional geometric parameters for a specific building. By calculation, he verifies them in the so-called “geometric plan” in the project documentation. The functional geometric parameters should be determined primarily for critical elements, i.e. for structures whose geometric accuracy is important for the execution of subsequent works, such as technologies requiring high precision and specific structures. The assumption is that designers will incorporate variations in geometric accuracy primarily in the development of the spatial parameters of the structures, which should ensure that the dimensional requirements for the completed structures will be met. One of these parameters is headroom. The design of headroom must respect the minimum height requirements prescribed by legislation, and where appropriate, by technical standards. At the same time, the design must respect the technological possibilities of the construction of individual structures – geometric deviations. To comply with the dimensional requirements for the completed structures, the geometric accuracy deviations should be determined in accordance with the requirements of the technical standards for the execution of the individual parts of the building structures and/or for their design. The aim of this article is to establish a calculation procedure for determining the safe design clearance so that the requirements of the legislation are met after implementation. The increase is determined based on a calculation procedure of the limiting geometric deviations that may affect the resulting headroom.

Electrical discharge machining (EDM) is one of the important machining processes to produce mold components. When using the EDM process, surface quality, processing time, accuracy, and electrode cost must be considered. The electrode wear is the main factor that causes error on the geometric accuracy, especially the workpiece corner. Therefore, this study proposes a novel electrode design to improve the geometric accuracy for the EDM process. Firstly, the effect of discharge current, electrode diameter, and depth of cut on the electrode wear and workpiece corner were investigated. Multiple regression and analysis of variant were used to analyze the experiment data. The electrode end-face design with compensation rule and algorithm was established based on the data analysis and error value. Furthermore, a compensated electrode end-face design system with human machine interface, which has a procedure guiding function, was developed. The system can design the electrode end-face for minimizing workpiece corner error and improve geometric accuracy. Finally, cutting experiments were conducted to verify the proposed method, and the results show that the proposed method can effectively enhance the geometric accuracy by around 22~37%. [ABSTRACT FROM AUTHOR]

As an important means of improving positioning accuracy, block adjustment has been used in the improvement and assessment of accuracy for the Chinese Gaofen-7 (GF-7) satellite. However, there is little research on what factors affect accuracy without ground control points (GCPs). The correlation between accuracy and the images participating in the adjustment is not clear. This paper proposes the correlation coefficients and canonical correlation analysis between five accuracy indicators and three sets of ten adjustment factors, including topographic factors, participating image factors, and tie points (TPs) factors, to quantify the influence of adjustment factors on accuracy. Block adjustment without GCPs for GF-7 stereo imagery is verified in three study areas to evaluate the relationship between accuracy and adjustment factors. The results show that block adjustment without GCPs can improve direct positioning accuracy with an average improvement of 1.27 m in the planar direction and 0.13 m in the elevation direction. Moreover, plane accuracy is more easily affected by three sets of factors, while the influence on elevation accuracy is more balanced. The set of TP factors has the greatest influence on accuracy, and the image overlap is more critical than the image coverage area, number, and time periods. Topographic factors also play an important role, and the influence of the elevation factor with the highest canonical correlation coefficient (−0.71) is more significant than the other two factors, roughness, and slope. The results provide a reference for the improvement of adjustment accuracy without GCPs, the reasonable selection of adjustment images, the optimization of TPs, and the strategy of the partition processing of large-area block adjustment for GF-7 stereo imagery. [ABSTRACT FROM AUTHOR]

The geolocation accuracy of Synthetic Aperture Radar (SAR) images is crucial for their application in various industries. Five high-resolution SAR satellites, namely ALOS, TerraSAR-X, Cosmo-SkyMed, RadarSat-2, and Chinese YG-3, provide a vast amount of image data for research purposes, although their geometric accuracies differ despite similar resolutions. To evaluate and compare the geometric accuracy of these satellites under the same ground control reference, a validation field was established in Xianning, China. The rational function model (RFM) was used to analyze the geometric performance of the five satellites based on the Xianning validation field. The study showed that each image could achieve sub-pixel positioning accuracy in range and azimuth direction when four ground control points (GCPs) were placed in the corners, resulting in a root mean square error (RMSE) of 1.5 pixels. The study also highlighted the effectiveness of an automated GCP-matching approach to mitigate manual identification of points in SAR images, and results demonstrate that the five SAR satellite images can all achieve sub-pixel positioning accuracy in range and azimuth direction when four GCPs are used. Overall, the verification results provide a reference for SAR satellite systems' designs, calibrations, and various remote sensing activities. [ABSTRACT FROM AUTHOR]

Monitoring biodiversity in forests is crucial for their management and preservation, especially in light of increasing climatic disturbances. However, traditional methods of surveying forest biodiversity, such as the inventory of tree-related microhabitats (TreMs), are costly and time-consuming. For many years, terrestrial laser scanning (TLS) was the main method for producing highly accurate 3D models of forests. However, with recent advancements in 3D scanning technologies, there are now numerous alternatives available on the market. The aim of this study was to evaluate the performance of four different 3D data acquisition methods, i.e. close-range photogrammetry (CRP), fish-eye photogrammetry (FEP), mobile laser scanning (MLS), and mixed reality depth camera (MRDC), in terms of accuracy and ability to measure biodiversity (TreMs) at tree-stem level, in comparison to TLS. Analysis was performed based on geometric accuracy and point neighbourhood relevance. CRP was the most accurate alternative to TLS for TreM measurement with a median error of 1.5 cm, while FEP provided a good balance between accuracy (median error 1.4 cm) and speed of data collection. Although MLS showed promising results (median error 1.6 cm), noise in the point cloud limited its ability to identify TreMs. MRDC, on the other hand, had lower quality (median error 3.6 cm) and lower point density, making it unsuitable for TreM segmentation. Nevertheless, the study demonstrated the feasibility of augmenting the real world with virtual content at single-tree-stem level using mixed reality technology. Overall, the 3D scanning technologies presented hold great promise for recording the evolution of biodiversity at stem level.

Surface finishing of hard-alloy parts is investigated. The best conditions for preliminary and final finishing are established. The grid density of the resultant raster trajectory is q = 0.5–3.0 mm–1 for preliminary finishing and q = 5–7 mm–1 for final finishing. [ABSTRACT FROM AUTHOR]

With the advent of the Fourth Industrial Revolution, the manufacturing industry began to pay special attention to the introduction of solutions based on modern technologies. These include rapid prototyping techniques, which are also popularly known as 3D printing. As the 3D printing industry develops around the world, new brands of machine manufacturers, as well as companies providing services in this field, keep appearing. Thus, a need has arisen to organize and systematize processes and define certain quality standards. In line with Industry 4.0, it is also extremely important to consider modern production management solutions that use IT systems to integrate networked distributed components of manufacturing processes. In this context, a research gap has been observed in the development of a quality control procedure for 3D prints that can be implemented in an in-house cloud. For this reason, the main objective of the paper is to present the author's online platform, which presents a sample procedure for quality control of 3D models. The paper also analyzes the costs associated with the quality control of 3D models assuming that the company has its own infrastructure, manufacturing components and qualified staff.

On the basis of the formulated concepts of designbased additive synthesis, methodological, algorithmic and software for basing (orientation) of models of machine parts in the working area of a 3D printer is presented, the essence of which is the sequential determination and identification of possible compositions of surface orientation bases, determining the parameters of geometric accuracy of a 3D printer, the formation of a basic coordinate system (by superimposing geometric connections on the model) and its binding to the coordinate system of a 3D printer. With the help of the software, it is possible, as early as at the design stage, to predict the accuracy of the tolerances of the relative position of surfaces in 3D printing and to recommend options for basing models of parts in the working area of a 3D printer based on an analysis of its geometric accuracy to ensure these tolerances. These applications can be used by design departments of enterprises where 3D printers are used, by IT companies for creating and improving slicer programs, by educational institutions for training specialists in the field of manufacturing products based on three-dimensional technologies. Цель работы – разработка методического, алгоритмического и программного обеспечения базирования моделей деталей машин в рабочей зоне 3D-принтеров на основе анализа их геометрической точности для обеспечения заданных чертежом допусков взаимного расположения поверхностей. Для исследования и решения, поставленных в работе задач, использовались методы теории базирования, теории автоматизации проектирования, системно-структурного анализа и моделирования. Предложена система терминов проектного базирования при аддитивном синтезе, которая за счет определения понятий геометрической модели детали, приоритетного допуска, состава и комплекта баз, схемы базирования позволила предложить последовательность процедур базирования (ориентации) моделей деталей машин в рабочей зоне 3D-принтеров. Последовательность процедур включает: определение и индентификацию возможных составов баз ориентации поверхностей, определение параметров геометрической точности 3D-принтера, формирование базовой системы координат (за счет наложения на модель геометрических связей) и ее привязку к системе координат 3D-принтера и уже на стадии проектирования дает возможность оценить достижимость заданных чертежом допусков взаимного расположения поверхностей, а также рекомендовать варианты ориентации модели детали в рабочей зоне 3D-принтера для обеспечения допусков взаимного расположения. Представление описанной методики на языке теории автоматизации проектирования, алгебры логики и теории алгоритмов дало возможность создать программное обеспечение, позволяющее прогнозировать обеспечение точности допусков взаимного расположения поверхностей при 3D-печати, рекомендовать варианты базирования моделей деталей в рабочей зоне 3D- принтера на основе анализа его геометрической точности для обеспечения допусков взаимного расположения и, как следствие, снизить вероятность печати бракованных деталей. Разработки могут использоваться в: проектных бюро предприятий, использующих 3D- принтеры; IT-компаниях для создания и совершенствования программ-слайсеров; учебном процессе для подготовки специалистов в области производства изделий на основе трёхмерных технологий.

Single Point Incremental Forming (SPIF) is an emerging sheet metal forming process which has been used in the prototype production of complex geometries. The geometric inaccuracies and quality of formed parts are the major obstructions in commercialization of SPIF process. The aim of presented work is to study this hindrance using experimental and numerical investigation on Aluminum Alloy 2210-O. Parametric optimization is done using Response Surface Methodology (RSM) for quality factor (surface roughness) and geometric accuracy (Maximum wall angle) while minimizing thickness reduction and forming time. For this purpose, three experimental setups were designed in this study, using tool types and tool paths. During investigation, the interaction and main effects of process parameters, viz. feed rate, spindle speed, and step increment are evaluated on surface roughness (Ra), maximum wall angle (α max) , % thickness reduction (% TR), and forming time (T) using ANOVA method. Results showed that among all the parameters of SPIF process, step increment is the most significant parameter for both forming paths using ball end and flat end tool. The comparative analysis of this study suggested that the ball end tool using the bidirectional path was better than the other setups. Furthermore, the results revealed that the ball end tool using a spiral path was better in desirability achievement (73%) as compared to the flat end tool using a spiral path (71.2%). The findings of this study are beneficial in paving a path for optimization of the SPIF process for an industrial-scale production of Al alloy AA 2219-O with desired characteristics. [ABSTRACT FROM AUTHOR]

At present, some mapping satellites, such as GaoFen-7 and ZiYuan3-03, are equipped with both optical stereo cameras and laser altimeters that can synchronously obtain stereo images and sparse ground laser altimetry points (LAPs). To effectively improve the geometric accuracy of these satellite stereo images, this study proposed an integrated processing method for LAPs and stereo images derived from the same satellite. This method makes full use of the advantages of synchronously obtaining stereo images and LAPs, and designs measurement technology for accurate pixel coordinates of LAPs in stereo images, which works toward solving a technical difficulty that has restricted their integration to achieve higher accuracy. The method also constructs a combined block adjustment model of LAPs and stereo images. We selected 70 GaoFen-7 stereo images and 463 GaoFen-7 LAPs from Hebei Province, China, and 12 ZiYuan3-03 stereo images and 81 ZiYuan3-03 LAPs from Heilongjiang Province, China, to conduct integrated processing experiments. The vertical accuracy of the GaoFen-7 images in all types of terrain were improved substantially and reached the accuracy requirements of 1:10,000 (even 1:5000) scale mapping in China. The vertical accuracy of the ZiYuan3-03 images in various terrain areas were also improved markedly, satisfying the accuracy requirement of 1:50,000 scale mapping. These experimental results indicate that the working mode of synchronously obtaining LAPs and stereo images using the same satellite is advanced, and the proposed method is correct and effective. [ABSTRACT FROM AUTHOR]

The object of research in the work is the technology of manufacturing shaped castings in disposable sand molds. The existing problem is that the imperfection of design and technological solutions at the stage of developing the technology of a single sand mold casting leads to deviations in the dimensions and geometry of the castings after their manufacture from the requirements of technological documentation. This can lead to an irreparable shortage of casting. To develop measures to eliminate or minimize the event, which consists in the formation of a shortage of castings in terms of dimensional and geometric accuracy, a procedure for searching for optimal design and technological solutions is proposed. A hypothesis has been put forward that a significant factor that leads to deviations in the dimensional and geometric accuracy of castings from the requirements of technological documentation is the imperfection of the gating system design. It is demonstrated on specific castings how this factor can influence the formation of uneven wall thickness. The proposed procedure, which includes 10 consecutive steps, allows to build a plan for a complete factorial experiment and obtain a regression equation for it, linking the parameters of the gating system with indicators of dimensional and geometric accuracy. The presence of such equations provides the possibility of further experimental optimization and determination of design and technological solutions for the development or improvement of casting systems that minimize the deviations of the dimensional and geometric accuracy of castings from the requirements of technological documentation. This also minimizes the likelihood of an event consisting in the formation of an irreparable shortage of castings. The presented study will be useful for machine-building enterprises that have foundries in their structure, where shaped castings are made in disposable sand molds. [ABSTRACT FROM AUTHOR]

[Display omitted] • 3D-printed HIPEs for elderly nutrition were achieved by citrus fiber and OSA starch. • Citrus fibers primarily filled among the droplet to increase shape retention of 3D printed products. • Low dosage of citrus fibers (0.1 %–0.4 %) enhanced the stability of OSA starch emulsions in 3D printing. • The prepared HIPEs had smooth texture and easy-to-chew properties for the elderly. 3D printing ready-to-eat emulsions using trans -fat-free edible oil, presents a significant challenge due to the complexities involved in achieving the necessary material structure, rheological properties, and stability. This study fabricated High Internal Phase Emulsions (HIPEs) stabilized with citrus fibers and octenyl succinic anhydride (OSA) modified waxy starch, serving as the printable inks for 3D-printable elderly foods. These printable inks exhibited a pseudoplastic gel structure, which provided enhanced extrudability and improved shape retention. The incorporation of citrus fiber, water, OSA starch, sunflower oil at a concentration of 0.3 wt%, 22.7 % wt %, 2 % wt%, 75 wt% in the 3D-printed HIPEs resulted in optimal addition, yielding the highest level of shape accuracy. Compared to the addition of OSA-modified starch, microstructural analysis and rheological testing (using Lissajous-Bowditch plots) indicated that the addition of citrus fiber had a greater impact on the rheological and textural properties of the HIPEs, which improved shape retention and fluidity of the HIPEs, and ensure the stability of continuous extrusion printing. Additionally, bionic tribological properties demonstrated that tribological properties of the prepared HIPEs were very close to the ones of mayonnaise, which indicating that the prepared HIPEs had smooth texture and easy-to-chew properties for the elderly. These findings offered a comprehensive understanding of the structure–function relationship between the molecular structures of HIPEs and their 3D printability, providing technical insights for the development of 3D-printed emulsion-based ready-to-eat elderly food products. This study provided a good industrialized method for HIPEs stabilized with only fruit dietary fiber and modified starch, and facilitated the development of emulsion-based ready-to-eat food products with 3D printability. [ABSTRACT FROM AUTHOR]

Traumatic brain injury (TBI) is a serious global health issue, leading to serious disabilities. One type of TBI is acute subdural haematoma (ASDH), which occurs when a bridging vein ruptures. Many numerical models of these structures, mainly based on the finite element method, have been developed. However, most rely on linear elasticity (without validation) and others on simplifications at the geometrical level. An example of the latter is the assumption of a regular cylinder with a constant radius, or the geometry of the vein acquired from medical images. Unfortunately, these do not replicate the real conditions of a mechanical tensile test. In this work, the main goal is to evaluate the influence of the vein’s geometry in its mechanical behaviour under tensile loading, simulating the real conditions of experimental tests. The second goal is to implement a hyperelastic model of the bridging veins where it would be possible to observe its non-linear elastic behaviour. The results of the developed finite element models were compared to experimental data available in the literature and other models. It was possible to conclude that the geometry of the vein structure influences the tensile stress–strain curve, which means that flattened specimens should be modelled when validating constitutive models for bridging veins. Additionally, the implementation of hyperelastic material models has been verified, highlighting the potential application of the Marlow and reduced polynomial (of fourth and sixth orders) constitutive models.

Flow spinning is an advantageous technology in forming thin-walled cylindrical parts, but for cylindrical parts with inner ribs,the height of the inner ribs that can be formed is limited. Aimed at the problem that the inner ribs are difficult to fill in such components, a numerical simulation model of staggered spinning of thin-walled cylindrical parts with cross inner ribs is established based on Abaqus, and the influence of the number of rollers on the filling of inner ribs is analyzed. The process test of the cylinder part with orthogonal inner ribs is conducted. The results show that in the staggered spinning process, increasing the number of rollers will reduce the diameter expansion of the aluminum alloy cylindrical part with inner ribs, and inhibit the axial flow of materials, leading to a higher geometric accuracy of the inner ribs. The comparison of the simulation results and the test results shows that the average error of the inner rib filling fullness of simulation result is 11.3%, and the simulation model has a good reliability.

The machining of large thin-walled rings is considered. The influence of the cutter geometry and the cutting conditions on the machining precision is analyzed by the finite-element method. Production experiments are compared with the theoretical analysis. Practical recommendations are formulated. [ABSTRACT FROM AUTHOR]