Journal articles: 'Dimensional and shape accuracy'

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Miao, Zixiao, and Qican Zhang. "Dual-frequency fringe for improving measurement accuracy of three-dimensional shape measurement." Chinese Optics Letters 19, no. 10 (2021): 102601. http://dx.doi.org/10.3788/col202119.102601.

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Zhu, Qi, and Philippe H. Geubelle. "Dimensional Accuracy of Thermoset Composites: Shape Optimization." Journal of Composite Materials 36, no. 6 (March 2002): 647–72. http://dx.doi.org/10.1177/0021998302036006485.

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Motoc, I., G. R. Marshall, R. A. Dammkoehler, and J. Labanowski. "Molecular Shape Descriptors. 1. Three-Dimensional Molecular Shape Descriptor." Zeitschrift für Naturforschung A 40, no. 11 (November 1, 1985): 1108–13. http://dx.doi.org/10.1515/zna-1985-1106.

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The paper presents and illustrates a method which uses numerical integration of the van der Waals envelope(s) to calculate with desired accuracy the molecular van der Waals volume and the three-dimensional molecular shape descriptor defined as the twin-number [OV(α, β); NOV(β, α), where OV and NOV represent the overlapping and, respectively, the nonoverlapping van der Waals volumes of the molecules α and ß superimposed according to appropriate criteria.

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Ruan, Xiongtao, and Robert F. Murphy. "Evaluation of methods for generative modeling of cell and nuclear shape." Bioinformatics 35, no. 14 (December 7, 2018): 2475–85. http://dx.doi.org/10.1093/bioinformatics/bty983.

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Abstract Motivation Cell shape provides both geometry for, and a reflection of, cell function. Numerous methods for describing and modeling cell shape have been described, but previous evaluation of these methods in terms of the accuracy of generative models has been limited. Results Here we compare traditional methods and deep autoencoders to build generative models for cell shapes in terms of the accuracy with which shapes can be reconstructed from models. We evaluated the methods on different collections of 2D and 3D cell images, and found that none of the methods gave accurate reconstructions using low dimensional encodings. As expected, much higher accuracies were observed using high dimensional encodings, with outline-based methods significantly outperforming image-based autoencoders. The latter tended to encode all cells as having smooth shapes, even for high dimensions. For complex 3D cell shapes, we developed a significant improvement of a method based on the spherical harmonic transform that performs significantly better than other methods. We obtained similar results for the joint modeling of cell and nuclear shape. Finally, we evaluated the modeling of shape dynamics by interpolation in the shape space. We found that our modified method provided lower deformation energies along linear interpolation paths than other methods. This allows practical shape evolution in high dimensional shape spaces. We conclude that our improved spherical harmonic based methods are preferable for cell and nuclear shape modeling, providing better representations, higher computational efficiency and requiring fewer training images than deep learning methods. Availability and implementation All software and data is available at http://murphylab.cbd.cmu.edu/software. Supplementary information Supplementary data are available at Bioinformatics online.

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OSAWA, Sonko, Toshiyuki TAKATSUJI, and Osamu SATO. "High accuracy three-dimensional shape measurements for supporting manufacturing industries." Synthesiology English edition 2, no. 2 (2009): 95–106. http://dx.doi.org/10.5571/syntheng.2.95.

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Beniak, J., P. Križan, Ľ. Šooš, and M. Matúš. "Research on Shape and Dimensional Accuracy of FDM Produced Parts." IOP Conference Series: Materials Science and Engineering 501 (April 9, 2019): 012030. http://dx.doi.org/10.1088/1757-899x/501/1/012030.

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Tian, Liang, Jing Liu, and Wei Guo. "Three-Dimensional Face Reconstruction Using Multi-View-Based Bilinear Model." Sensors 19, no. 3 (January 23, 2019): 459. http://dx.doi.org/10.3390/s19030459.

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Face reconstruction is a popular topic in 3D vision system. However, traditional methods often depend on monocular cues, which contain few feature pixels and only use their location information while ignoring a lot of textural information. Furthermore, they are affected by the accuracy of the feature extraction method and occlusion. Here, we propose a novel facial reconstruction framework that accurately extracts the 3D shapes and poses of faces from images captured at multi-views. It extends the traditional method using the monocular bilinear model to the multi-view-based bilinear model by incorporating the feature prior constraint and the texture constraint, which are learned from multi-view images. The feature prior constraint is used as a shape prior to allowing us to estimate accurate 3D facial contours. Furthermore, the texture constraint extracts a high-precision 3D facial shape where traditional methods fail because of their limited number of feature points or the mostly texture-less and texture-repetitive nature of the input images. Meanwhile, it fully explores the implied 3D information of the multi-view images, which also enhances the robustness of the results. Additionally, the proposed method uses only two or more uncalibrated images with an arbitrary baseline, estimating calibration and shape simultaneously. A comparison with the state-of-the-art monocular bilinear model-based method shows that the proposed method has a significantly higher level of accuracy.

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Petrak, D., S. Dietrich, G. Eckardt, and M. Köhler. "Two-dimensional particle shape analysis from chord measurements to increase accuracy of particle shape determination." Powder Technology 284 (November 2015): 25–31. http://dx.doi.org/10.1016/j.powtec.2015.06.036.

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Kane, J. H., G. Zhao, H. Wang, and K. Guru Prasad. "Boundary Formulations for Three-Dimensional Continuum Structural Shape Sensitivity Analysis." Journal of Applied Mechanics 59, no. 4 (December 1, 1992): 827–34. http://dx.doi.org/10.1115/1.2894049.

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The direct, singular, boundary element analysis formulation is shown to provide a basis for a computationally efficient and accurate shape design sensitivity analysis approach for the structural response of three-dimensional solid objects. The theoretical formulation for surface displacement and traction component sensitivities, and all components of the stress tensor is presented along with a formulation for the recovery of displacement and stress components in the interior of the object under consideration. Discussion of computational issues related to the overall efficiency of these formulations is given, along with numerical results to demonstrate the accuracy and efficiency of this approach.

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Wu, Ge, Duan Li, Pengpeng Hu, Yueqi Zhong, and Ning Pan. "Foot shape prediction using elliptical Fourier analysis." Textile Research Journal 88, no. 9 (February 17, 2017): 1026–37. http://dx.doi.org/10.1177/0040517517693983.

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In this paper, a new method was proposed to establish the relationship between three-dimensional (3D) foot shapes and their two-dimensional (2D) foot silhouettes, through which a complete 3D foot shape can be predicted by simply inputting its two 2D silhouettes. 3D foot scans of 80 participants were randomly selected as the training set, and those of another 20 participants were used as the testing set. Elliptical Fourier analysis (EFA) and principle component analysis (PCA) were adopted to parameterize the 3D foot shapes. A linear regressive model was then developed to predict the 3D foot shape with the foot silhouettes. Experiment results indicated individual 3D foot shape can be predicted with a mean error between 1.21 and 1.27 mm, which can provide enough accuracy for the fit evaluation of footwear.

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Sato, Takahiro, Kota Watanabe, and Hajime Igarashi. "Accuracy evaluation of three-dimensional FE analysis based on nonconforming voxel element." COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering 33, no. 1/2 (December 20, 2013): 181–90. http://dx.doi.org/10.1108/compel-10-2012-0232.

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Purpose – Three-dimensional (3D) mesh generation for shape optimizations needs long computational time. This makes it difficult to perform 3D shape optimizations. The purpose of this paper is to present a new meshing method with light computational cost for 3D shape optimizations. Design/methodology/approach – This paper presents a new meshing method on the basis of nonconforming voxel finite element method. The 3D mesh generation is performed with light computational cost keeping the computational accuracy. Findings – It is shown that the computational cost for 3D mesh generation can be reduced without deteriorating numerical accuracy in the FE analysis. It is reported the performance of the present method. Originality/value – The validity of the nonconforming voxel elements is tested to apply it to the optimization of 3D optimizations.

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Sahin and, A. Z., and I. Dincer. "Determination of Drying Times for Irregular Two and Three-Dimensional Objects." Journal of Heat Transfer 125, no. 6 (November 19, 2003): 1190–93. http://dx.doi.org/10.1115/1.1603778.

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This paper deals with development of a new analytical model for determining the drying times of irregular-shaped multi-dimensional objects. Geometrically irregular two and three-dimensional products are approximated by elliptical cylinder and ellipsoidal shapes, respectively. Using experimental drying parameters that are available from the literature, drying times of irregular, multi-dimensional products are determined through the present models. Geometric shape factors for the elliptic cylinder and ellipsoid are employed and based on the reference drying time for an infinite slab. In addition, the present models are verified through comparison with experimental drying times of several food products. The accuracy of the predictions using the present models is then discussed, and a considerably high agreement is obtained between the predictions and experimental data.

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Behera, Amar Kumar, Bin Lu, and Hengan Ou. "Characterization of shape and dimensional accuracy of incrementally formed titanium sheet parts." MATEC Web of Conferences 21 (2015): 04014. http://dx.doi.org/10.1051/matecconf/20152104014.

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Kang, Jae-Gwan, and Jong-Yun Jung. "Effective Process Parameters on Shape Dimensional Accuracy in Incremental Sheet Metal Forming." Journal of Society of Korea Industrial and Systems Engineering 38, no. 4 (December 30, 2015): 177–83. http://dx.doi.org/10.11627/jkise.2015.38.4.177.

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Krivoš, E., R. Pastirčák, and R. Madaj. "Effect of Technological Parameters on the Quality and Dimensional Accuracy of Castings Manufactured by Patternless Process Technology." Archives of Metallurgy and Materials 59, no. 3 (October 28, 2014): 1069–72. http://dx.doi.org/10.2478/amm-2014-0182.

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Abstract Submitted article deals with the effect of selected technological parameters on the quality and dimensional accuracy of prototype castings made by Patternless process technology. During experiments were used two types of molding compounds (foamed gypsum and compound based on silica sand and resin). Experiments were focused on optimization of cutting parameters in terms of efficiency, accuracy and possibilities to minimize tool wear. Article deals also with the dimensional and shape accuracy of the castings made by Z-Cast technology. The main aim of the research is to optimize Patternless process technology to such an extent, that achieved dimensional and shape accuracy will be comparable to castings made by the Z-Cast technology.

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Konrad, Tobias, Steffen Schöllhammer, Karl Roll, and Marion Merklein. "Influence of Geometrical Shapes and Sheet Thicknesses on the Dimensional Accuracy of Single and Assembled Parts." Key Engineering Materials 716 (October 2016): 923–30. http://dx.doi.org/10.4028/www.scientific.net/kem.716.923.

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Based on elastic stress and strain states after forming and joining processes, single and assembled parts show deviations regarding their dimensional accuracy. Therefore an analysis of selected influencing factors and their influence on the dimensional accuracy of assembled parts is performed in this paper. In this article a novel approach is presented that characterizes the impact of three geometrical shapes (convex/concave/straight) and different sheet thicknesses on the dimensional accuracy along a linked forming and joining process chain. The process chain consists of a deep drawing and a clinching process. Depending on sheet thickness, material and geometrical shape, the dimensional accuracy of single parts and joined assemblies varies. For the single parts the geometry of the specimen S-rail is used. Several types of assemblies are used for the proposed approach combining this specimen with a plane sheet or a second S-rail. The FEM-tools LS-DYNA and Abaqus, are used to demonstrate this approach. Simulations and experiments with aluminum alloy 6014, mild steel CR3 and sheet thicknesses of 0.7, 1.0 and 2.0 mm are conducted for single and assembled parts. In summary, a significant improvement of the dimensional accuracy of an S-rail assembly is demonstrated using two non-dimensional accurate single parts. Future work will be to analyze frequently occurring part segmentations for the joining technologies and to optimize material mix and sheet thicknesses in order to improve deviations of the assembly to the nominal CAD geometry.

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Miller, Bartosz, and Leonard Ziemiański. "Identification of Mode Shapes of a Composite Cylinder Using Convolutional Neural Networks." Materials 14, no. 11 (May 25, 2021): 2801. http://dx.doi.org/10.3390/ma14112801.

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The aim of the following paper is to discuss a newly developed approach for the identification of vibration mode shapes of multilayer composite structures. To overcome the limitations of the approaches based on image analysis (two-dimensional structures, high spatial resolution of mode shapes description), convolutional neural networks (CNNs) are applied to create a three-dimensional mode shapes identification algorithm with a significantly reduced number of mode shape vector coordinates. The CNN-based procedure is accurate, effective, and robust to noisy input data. The appearance of local damage is not an obstacle. The change of the material and the occurrence of local material degradation do not affect the accuracy of the method. Moreover, the application of the proposed identification method allows identifying the material degradation occurrence.

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Wang, Jing Ling, Zhong Yr Cai, Mine Zhe Li, and Hui Yang. "Influence of Element Number on Shape Accuracy in Multi-Point Stretch Forming of Air Craft." Applied Mechanics and Materials 130-134 (October 2011): 2240–44. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.2240.

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Multi-point stretch forming is a flexible manufacturing technique for three-dimensional shape forming of craft skin. Its die surface is constructed by many pairs of matrices of elements whose height is controlled by computer. It uses the curved surface of elements instead of the die surface. The element numberis an important parameter because it has great influence on the part quality. This paper simulates the forming process of paraboloid part and saddle-shaped part with different number of elements and studies the influence of element number on the shape accuracy of the part .That will provides guidance for the application of multi-point stretch forming.

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Iwabe, Hiroyasu, Hideaki Matsuhashi, Hayato Akutsu, Tomoyuki Shioya, and Hitoshi Takao. "High-Accuracy Machining of Thin-Walled Workpiece by Non-Rotational Tool-Analysis of Machining Accuracy Based on Deflection of Tool and Workpiece Using FEM-." International Journal of Automation Technology 4, no. 3 (May 5, 2010): 243–51. http://dx.doi.org/10.20965/ijat.2010.p0243.

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In this paper, the FEM analysis and the machining of a workpiece using a non-rotational tool are attempted in order to produce a highly accurate surface on a thin wall. Also, the machining accuracy of the thin wall produced by the non-rotational tool is compared with that produced by an end mill. The main results are as follows. (1) FEM models for the tool and workpiece are made and the machining accuracy is predicted based on the deflection analysis using FEM due to the cutting force. (2) The tendency of the shape of machined surface is almost coincident with that of the predicted shape, so the propriety of the method of analysis is verified. (3) Both dimensional and shape error on the inside and outside surfaces of the workpiece produced by the non-rotational tool prove larger than the predicted values. Although the shape error proved a little larger than the predicted value, the target value of 5μm was achieved. (4) It is shown that the dimensional error due to under cutting decreases with the decrease in the radius of the tool edge. And also, on and after the second cutting process, the cutting at the commanded depth of cut was achieved even if the micro depth of cut.

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Liu, Cheng-Yang, and Chung-Yi Wang. "Investigation of Phase Pattern Modulation for Digital Fringe Projection Profilometry." Measurement Science Review 20, no. 1 (February 1, 2020): 43–49. http://dx.doi.org/10.2478/msr-2020-0006.

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AbstractThe fringe projection profilometry with sinusoidal patterns based on phase-shifting algorithms is commonly distorted by the nonlinear intensity response of commercial projector. In order to solve this issue, sinusoidal width modulation is presented to generate binary sinusoidal patterns for defocusing the projection. However, the residual errors in the phase maps are usually notable for highly accurate three-dimensional shape measurements. In this paper, we propose the fringe patterns of the sinusoidal, square, and triangular periodic waveforms with seven-step phase-shifting algorithm to further improve the accuracy of three-dimensional profile reconstruction. The absolute phase values are calculated by using quality guided path unwrapping. We learn that by properly selecting fringe patterns according to the target shape, the undesired harmonics of the measured surface have negligible effect on the phase values. The experiments are presented to verify the imaging performances of three fringe patterns for different testing targets. The triangular fringe patterns are suitable for the shape measurements of complex targets with curved surfaces. The results provide a great possibility for high-accuracy shape measurement technique with wider measuring depth range.

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Jakrapanichakul, D., K. Tanabe, M. Belohlavek, and J. B. Seward. "Shape reconstruction of the left ventricle: accuracy of limited-plane three-dimensional echocardiography." Journal of Ultrasound in Medicine 20, no. 7 (July 2001): 767–74. http://dx.doi.org/10.7863/jum.2001.20.7.767.

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Ahn, Jae Seok, Kwang Ik Son, Kwang Sung Woo, and Young Shik Shin. "Singular Behavior of Laminated Skew Composite Materials with Cross-Ply Stacking." Advanced Materials Research 538-541 (June 2012): 1640–45. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.1640.

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This study deals with effects depending on skew angles in skewed-laminated composite materials in macroscopic point of view. Based on higher-order approximation of displacements, subparametric layer-wise finite elements are used to analyze skewed-laminated composite systems. The elements have higher-order shape functions derived from the Lobatto shape functions. The modes of the elements are classified into three groups such as vertex, side, and internal modes. The vertex modes have physical meaning, while side and internal modes with respect to the increase of order of the Lobatto shape functions do not have physical meaning but improve accuracy of analysis. Therefore, fixing mesh arrangement of present analysis, the quality of the analysis can be enhanced without re-meshing work. The approach based on p-version of finite element method is implemented with three-dimensional elasticity theory, while shape functions are developed by combination of one- and two-dimensional shape functions, not using three-dimensional shape functions. Using the accurate and practical proposed technique, macroscopic behavior of skewed-laminated composite materials is investigated.

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Toyoda, Masahiro, Kota Funahashi, Takeshi Okuzono, and Kimihiro Sakagami. "Predicted Absorption Performance of Cylindrical and Rectangular Permeable Membrane Space Sound Absorbers Using the Three-Dimensional Boundary Element Method." Sustainability 11, no. 9 (May 13, 2019): 2714. http://dx.doi.org/10.3390/su11092714.

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Three-dimensional, permeable membrane space sound absorbers have been proposed as practical and economical alternatives to three-dimensional, microperforated panel space sound absorbers. Previously, the sound absorption characteristics of a three-dimensional, permeable membrane space sound absorber were predicted using the two-dimensional boundary element method, but the prediction accuracy was impractical. Herein, a more accurate prediction method is proposed using the three-dimensional boundary element method. In the three-dimensional analysis, incident waves from the elevation angle direction and reflected waves from the floor are considered, using the mirror image. In addition, the dissipated energy ratio is calculated based on the sound absorption of a surface with a unit sound absorption power. To validate the three-dimensional numerical method, and to estimate the improvement in prediction accuracy, the results are compared with those of the measurements and two-dimensional analysis. For cylindrical and rectangular space sound absorbers, three-dimensional analysis provides a significantly improved prediction accuracy for any shape and membrane sample that is suitable for practical use.

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Nawka, Marie Teresa, Jan-Hendrik Buhk, Susanne Gellissen, Jan Sedlacik, Jens Fiehler, and Andreas Maximilian Frölich. "A new method to statistically describe microcatheter tip position in patient-specific aneurysm models." Journal of NeuroInterventional Surgery 11, no. 4 (October 16, 2018): 425–30. http://dx.doi.org/10.1136/neurintsurg-2018-014259.

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Background and purposeEvidence on how to select microcatheters to facilitate aneurysm catheterization during coil embolization is sparse. We developed a new method to define microcatheter tip location inside a patient-specific aneurysm model as a 3-dimensional probability map. We hypothesized that precision and accuracy of microcatheter tip positioning depend on catheter tip shape and aneurysmal geometry.Materials and methodsUnder fluoroscopic guidance two to three operators introduced differently shaped microcatheters (straight, 45°, 90°) into eight aneurysm models targeting the anatomic center of the aneurysm. Each microcatheter position was recorded with flat-panel CT, and 3-dimensional probability maps of the microcatheter tip positions were generated. Maps were assessed with histogram analyses and compared between tip shapes, aneurysm locations and operators.ResultsAmong a total of 530 microcatheter insertions, the precision (mean distance between catheter positions) and accuracy (mean distance to target position) were significantly higher for the 45° tip (1.10±0.64 mm, 3.81±1.41 mm, respectively) than for the 90° tip (1.27±0.57 mm, p=0.010; 4.21±1.60 mm p=0.014, respectively). Accuracy was significantly higher in posterior communicating artery aneurysms (3.38±1.20 mm) than in aneurysms of the internal carotid artery (4.56±1.54 mm, p<0.001).ConclusionOur method can be used tostatistically describe statistically microcatheter behavior in patient-specific anatomy, which may improve the available evidence guiding microcatheter shape selection. Experience increases the ability to reach the intended position with a microcatheter (accuracy) that is also dependent on the aneurysm location, whereas catheter tip choice determines the variability of catheter tip placements versus each other (precision). Clinical validation is required.

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Burek, Jan, Paweł Sułkowicz, and Robert Babiarz. "Traverse grinding of low-stiffness shafts with the use of a grinding wheel’s path correction." Mechanik 91, no. 8-9 (September 10, 2018): 741–43. http://dx.doi.org/10.17814/mechanik.2018.8-9.120.

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This paper presents a method of increasing the shape and dimensional accuracy of low-stiffness shafts manufactured in traverse grinding process. In order to achieve that, grinding force measurement was used. It allowed to calculate such a correction of a grinding wheel’s path, that allowed to decrease dimensional and shape errors of grinded workpieces.

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Ng, Bennett K., Markus J. Sommer, Michael C. Wong, Ian Pagano, Yilin Nie, Bo Fan, Samantha Kennedy, et al. "Detailed 3-dimensional body shape features predict body composition, blood metabolites, and functional strength: the Shape Up! studies." American Journal of Clinical Nutrition 110, no. 6 (September 25, 2019): 1316–26. http://dx.doi.org/10.1093/ajcn/nqz218.

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ABSTRACT Background Three-dimensional optical (3DO) body scanning has been proposed for automatic anthropometry. However, conventional measurements fail to capture detailed body shape. More sophisticated shape features could better indicate health status. Objectives The objectives were to predict DXA total and regional body composition, serum lipid and diabetes markers, and functional strength from 3DO body scans using statistical shape modeling. Methods Healthy adults underwent whole-body 3DO and DXA scans, blood tests, and strength assessments in the Shape Up! Adults cross-sectional observational study. Principal component analysis was performed on registered 3DO scans. Stepwise linear regressions were performed to estimate body composition, serum biomarkers, and strength using 3DO principal components (PCs). 3DO model accuracy was compared with simple anthropometric models and precision was compared with DXA. Results This analysis included 407 subjects. Eleven PCs for each sex captured 95% of body shape variance. 3DO body composition accuracy to DXA was: fat mass R2 = 0.88 male, 0.93 female; visceral fat mass R2 = 0.67 male, 0.75 female. 3DO body fat test-retest precision was: root mean squared error = 0.81 kg male, 0.66 kg female. 3DO visceral fat was as precise (%CV = 7.4 for males, 6.8 for females) as DXA (%CV = 6.8 for males, 7.4 for females). Multiple 3DO PCs were significantly correlated with serum HDL cholesterol, triglycerides, glucose, insulin, and HOMA-IR, independent of simple anthropometrics. 3DO PCs improved prediction of isometric knee strength (combined model R2 = 0.67 male, 0.59 female; anthropometrics-only model R2 = 0.34 male, 0.24 female). Conclusions 3DO body shape PCs predict body composition with good accuracy and precision comparable to existing methods. 3DO PCs improve prediction of serum lipid and diabetes markers, and functional strength measurements. The safety and accessibility of 3DO scanning make it appropriate for monitoring individual body composition, and metabolic health and functional strength in epidemiological settings. This trial was registered at clinicaltrials.gov as NCT03637855.

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Liu, Hai Peng, Shi Qiao Gao, Lei Jin, and Yun Li He. "Corner Effect of Micro-Comb Capacitive Structure." Key Engineering Materials 609-610 (April 2014): 831–36. http://dx.doi.org/10.4028/www.scientific.net/kem.609-610.831.

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The comb-shaped capacitive micro-machined gyroscope employing an electrostatic comb drive and capacitive sensing structure is a typical type of MEMS sensor. Because of design and processing limitation and other factors, there are problems related to parallelism, dimensional accuracy and shape accuracy of the fabricated comb capacitor. These problems induce error into the calculation of the capacitance of the comb capacitor. The capacitance of the comb capacitor can be better calculated by the modeling the corner effect with various equipotential lines.

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Cao, Jingyi, and Yi Xue. "Characteristic chemical probing patterns of loop motifs improve prediction accuracy of RNA secondary structures." Nucleic Acids Research 49, no. 8 (April 13, 2021): 4294–307. http://dx.doi.org/10.1093/nar/gkab250.

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Abstract RNA structures play a fundamental role in nearly every aspect of cellular physiology and pathology. Gaining insights into the functions of RNA molecules requires accurate predictions of RNA secondary structures. However, the existing thermodynamic folding models remain less accurate than desired, even when chemical probing data, such as selective 2′-hydroxyl acylation analyzed by primer extension (SHAPE) reactivities, are used as restraints. Unlike most SHAPE-directed algorithms that only consider SHAPE restraints for base pairing, we extract two-dimensional structural features encoded in SHAPE data and establish robust relationships between characteristic SHAPE patterns and loop motifs of various types (hairpin, internal, and bulge) and lengths (2–11 nucleotides). Such characteristic SHAPE patterns are closely related to the sugar pucker conformations of loop residues. Based on these patterns, we propose a computational method, SHAPELoop, which refines the predicted results of the existing methods, thereby further improving their prediction accuracy. In addition, SHAPELoop can provide information about local or global structural rearrangements (including pseudoknots) and help researchers to easily test their hypothesized secondary structures.

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Latiff, Zulkarnain Abdul, M. R. A. Rahman, and F. Saad. "Dimensional Accuracy Evaluation of Rapid Prototyping Fused Deposition Modeling Process of FDM200mc Machine on Basic Engineering Profiles." Applied Mechanics and Materials 465-466 (December 2013): 96–100. http://dx.doi.org/10.4028/www.scientific.net/amm.465-466.96.

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The purpose of this research is to study the accuracy of RP FDM Process. This research involves varying two parameters in building up the prototype which is the buildup angle and the sparse for each layer (volume of parts). The varying parameters were used in the FDM process for three types of specimen (profiles) which is the Cube, Cylinder and Pyramid. The varying parameters are the build up angle of 300, 650 and 900 and for the types of sparse, there are three types of sparse used which is Low Density (LD), High Density (HD) and Solid Type. The results of the dimensional accuracy are analyzed by calculating the percentage of difference of the dimensional measurement for the specimen and the actual dimension of it. The lesser difference, the better the dimensional accuracy. The conclusion of this study is the less complicated specimen shape for the FDM process, the more accurate of the dimensional accuracy with the optimum build up angle of 300 or less and the optimum type of sparse of Low Density Type (LD).

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Goo, Bona, Jong-Bong Kim, Dong-Gyu Ahn, and Keun Park. "Irreversible and Repeatable Shape Transformation of Additively Manufactured Annular Composite Structures." Materials 14, no. 6 (March 12, 2021): 1383. http://dx.doi.org/10.3390/ma14061383.

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Four-dimensional (4D) printing is a unique application of additive manufacturing (AM) which enables additional shape transformations over time. Although 4D printing is an interesting and attractive phenomenon, it still faces several challenges before it can be used for practical applications: (i) the manufacturing cost should be competitive, and (ii) the shape transformations must have high dimensional accuracy and repeatability. In this study, an irreversible and repeatable thermoresponsive shape transformation method was developed using a material extrusion type AM process and a plain thermoplastic polymer (ABS) without a shape-memory function. Various types of annular discs were additively manufactured using printing paths programmed along a circular direction, and additional heat treatment was conducted as a thermal stimulus. The programmed circumferential anisotropy led to a unique 2D-to-3D shape transformation in response to the thermal stimulus. To obtain more predictable and repeatable shape transformation, the thermal stimulus was applied while using a geometric constraint. The relevant dimensional accuracy and repeatability of the constrained and unconstrained thermal deformations were compared. The proposed shape transformation method was further applied to AM and to the in situ assembly of a composite frame–membrane structure, where a functional membrane was integrated into a curved 3D frame without any additional assembly procedure.

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Mariano, John, and William J. Hinze. "Modeling complexly magnetized two‐dimensional bodies of arbitrary shape." GEOPHYSICS 58, no. 5 (May 1993): 637–44. http://dx.doi.org/10.1190/1.1443447.

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A method has been devised for the forward computation of magnetic anomalies due to two‐dimensional (2-D) polygonal bodies with heterogeneously directed magnetization. The calculations are based on the equivalent line source approach wherein the source is subdivided into discrete elements that vary spatially in their magnetic properties. This equivalent dipole line method provides a fast and convenient means of representing and computing magnetic anomalies for bodies possessing complexly varying magnitude and direction of magnetization. The algorithm has been tested and applied to several generalized cases to verify the accuracy of the computation. The technique has also been used to model observed aeromagnetic anomalies associated with the structurally deformed, remanently magnetized Keweenawan volcanic rocks in eastern Lake Superior. This method is also easily adapted to the calculation of anomalies due to two and one‐half‐dimensional (2.5-D) and three‐dimensional (3-D) heterogeneously magnetized sources.

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Maciąg, Artur. "Three-dimensional wave polynomials." Mathematical Problems in Engineering 2005, no. 5 (2005): 583–98. http://dx.doi.org/10.1155/mpe.2005.583.

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We demonstrate a specific power series expansion technique to solve the three-dimensional homogeneous and inhomogeneous wave equations. As solving functions, so-called wave polynomials are used. The presented method is useful for a finite body of certain shape. Recurrent formulas to improve efficiency are obtained for the wave polynomials and their derivatives in a Cartesian, spherical, and cylindrical coordinate system. Formulas for a particular solution of the inhomogeneous wave equation are derived. The accuracy of the method is discussed and some typical examples are shown.

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Borrelli, R., S. Franchitti, C. Pirozzi, L. Carrino, L. Nele, W. Polini, L. Sorrentino, and A. Corrado. "Ti6Al4V Parts Produced by Electron Beam Melting: Analysis of Dimensional Accuracy and Surface Roughness." Journal of Advanced Manufacturing Systems 19, no. 01 (March 2020): 107–30. http://dx.doi.org/10.1142/s0219686720500067.

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Additive manufacturing (AM), applied to metal industry, is a family of processes that allows complex shape components to be realized from raw materials in the form of powders. Electron beam melting (EBM) is a relatively new additive manufacturing (AM) technology. Similar to electron-beam welding, EBM utilizes a high-energy electron beam as a moving heat source to melt metal powder, and 3D parts are produced in a layer-building fashion by rapid self-cooling. By EBM, it is possible to realize metallic complex shape components, e.g. fine network structures, internal cavities and channels, which are difficult to make by conventional manufacturing means. This feature is of particular interest in titanium industry in which numerous efforts are done to develop near net shape processes. In the field of mechanical engineering and, in particular, in the aerospace industry, it is crucial for quality certification purpose that components are produced through qualified and robust manufacturing processes ensuring high product repeatability. The contribution of the present work is to experimentally identify the EBM job parameters (sample orientation, location of the sample in the layer and height in the build chamber) that influence the dimensional accuracy and the surface roughness of the manufactured parts in Ti6Al4V. The repeatability of EBM is investigated too.

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Otsubo, Tatsuki, Takanori Yazawa, Reiko Yamada, Keita Fujii, Syunta Nakasage, Yukio Maeda, Ikuo Yamamoto, Yasuhiko Ougiya, and Tatsuhiro Kojima. "Accuracy of Three-Dimensional Shape Measurement Using a Triangulation Method Sensor with Optical Skid." Key Engineering Materials 656-657 (July 2015): 768–73. http://dx.doi.org/10.4028/www.scientific.net/kem.656-657.768.

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On-machine measurement is used in ultra-processing machining, but it is seldom used in precision machining. For on-machine measurement, it is necessary that the sensor not be easily affected by the moving error or environment vibration in the field of precision machining. A triangulation method sensor with the optical skid method made using a new design concept is proposed to remove the moving error and vibration. The optical skid method used two laser spots with different sizes: the small spot diameter is the stylus and the large spot diameter is the skid [1]. The difference between these two signals reflects the surface shape. The developed sensor comprises an optical source and two optical receiving systems. Each optical receiving system has an imaging lens and a detector. Instead of two laser spots of different sizes, two detectors with different sizes of receiving area serve as the optical skid. Results confirmed the possibility of reducing the influence of the vibration using the developed sensor. In on-machine measurements, measurement of the surface profile with long wavelength is often necessary. If the spot diameter of the skid is not much larger than the surface profile wavelength, then the smoothing effect of the skid is reduced. Therefore, the amplitude of the measured profile by the skid sensor is smaller than actual amplitude of the workpiece. This paper presents a method of reconstructing the surface profile from the measurement results and the obtained effects of the reconstruction method from simulations and experiments.

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McGarry, T., B. McHugh, A. Buis, and G. McKay. "Evaluation of the effect of shape on a contemporary CAD system." Prosthetics and Orthotics International 32, no. 2 (January 2008): 145–54. http://dx.doi.org/10.1080/03093640802015920.

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The TracerCAD system is one of the leading prosthetic CAD systems in the world and is increasingly used in clinics to replace traditional methods of residual limb shape capture. Accurate dimensional capture of the residuum is arguably the most important process in the production of a prosthetic socket. TracerCAD system accuracy has previously been tested on a cylindrical model but not a trans-tibial shape. Residual limbs are irregular in shape therefore it is important to assess if shape has an effect on the accuracy of data collected when using TracerCAD. The objective of this study is to investigate the accuracy of the TracerCAD system in measuring a model of a trans-tibial stump of known dimensions and volume. A model of a trans-tibial stump was produced and filled with plaster and measured using a data acquisition system with an accuracy of five micron (0.005 mm). The model was repeatedly traced using the TracerCAD system by an individual user. The mean value of measures taken by the dynamic indicator was calculated and compared to individual and mean values of TracerCAD measurement. Results showed that the TracerCAD measurement was not as consistent on the more complex trans-tibial model as for the cylindrical model.

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Furutani, Ryoshu, and Masakazu Watanabe. "Measurement of Straightness for Two-Dimensional Translatory Stage." Key Engineering Materials 437 (May 2010): 194–97. http://dx.doi.org/10.4028/www.scientific.net/kem.437.194.

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The large scaled and high accurate 2D-stage is necessary for nanomanufacturing. In order to measure the position of stage, two direction sensors are used. These sensors measure the displacement from the metrological frame. However in nanometer application, as the profile error of metrological frame is comparable with the accuracy of 2D-stage, it is not negligible. Therefore the measuring result includes the displacement of stages and the profile error of metrological frame. So the multi-probe method is applied in one-dimensional measurement to separate the displacement error from the profile error of the metrological frame. In the multi-probe method, the zero adjustment error cannot be removed. So this article proposes a new method which separates the displacement of 2D-stage from the profile errors of the metrological frames in two directions. In this article, as the laser interferometer is used as the sensor, the measuring data is assumed as the shape of the axis of stages mixed with the profile error of the reference mirror in laser interferometer. The relationship during the measuring data, the shape of the axis and the profile error is described. The shape of axis of stage and the profile error of mirror are derived from the measuring result in experiment.

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Pang, Gui Bing, D. M. Li, Wen Ji Xu, X. Adayi, L. Yang, and J. J. Zhou. "Theoretic and Experimental Study on the Accuracy of Gears by Generative Electrochemical Mechanical Finishing." Key Engineering Materials 487 (July 2011): 268–72. http://dx.doi.org/10.4028/www.scientific.net/kem.487.268.

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Gears’ accuracy has important influences on its working performance and life. Electrochemical mechanical finishing (ECMF) was applied to finish cylindrical gears. The influence of the generative type of ECMF was studied theoretically and experimentally on the shape of gear teeth, and on the dimensional accuracy between teeth, and that in the tooth thickness direction. The results indicate that the generative type of ECMF can improve the accuracy between teeth, as well, the dimensional accuracy of gear tooth and that in the thickness direction may be also improved.

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Park, J. H., S. G. Kim, Y. C. Park, and X. G. Song. "Shape design of the deep-drawing preform for manufacturing of automobile drum clutch hubs." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 226, no. 4 (September 9, 2011): 1016–24. http://dx.doi.org/10.1177/0954406211417495.

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A large variety of metal forming processes is required in manufacturing for automotive applications. Traditionally, the design process for metal forming tools is based on trial-and-error and on the skill of experienced die-makers. This approach results in high development cost and long lead-times. Especially, the drum clutch requires tight dimensional accuracy in inside diameter and gear shape because it is used as the main component for the automatic transmission. The drum clutch investigated in this study is formed in five forming steps, which are first deep drawing, second deep drawing, restriking, embossing, and Grob processes. Dimensional accuracy of the final products greatly depends upon how much more accurate pre-form is manufactured in the previous forming processes before the Grob process. The deep drawing, restriking, and embossing processes in which the pre-form is formed are very important and decisive steps. Thus in some cases, excessive strain by these operations causes dimensional inaccuracy and cracks initiated from the base and wall of the product. Based on the above background, the objective of this study is to optimize the pre-form shape and tooling so that excessive thinning and crack formation are avoided while a sharp corner radius and flatness are obtained. Process variables such as the punch shapes both of first and second deep drawing, and punch angle were selected to evaluate the deformation characteristics. The optimum parameters were determined from forming simulations using commercial finite element method codes, DEFORM-2D, specifically developed for metal forming simulation. Finally, experiments for the whole drum clutch forming processes were carried out to verify the optimized forming parameters and the analytical results.

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Murčinková, Zuzana, and Karol Vasilko. "Stiffness of Technological System and Final Accuracy of Turned and Milled Parts." Key Engineering Materials 686 (February 2016): 174–79. http://dx.doi.org/10.4028/www.scientific.net/kem.686.174.

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The paper analyzes static stiffness of technological system machine tool - cutting tool - workpiece as one of factors affecting machined part accuracy. It focuses on turning and milling and their tool and workpiece characteristics as size, geometry, stiffness, tool wear, clamping etc. The paper identifies inaccuracies as a result of deformation of elastic component joints during acting the cutting and clamping forces. The paper provides final shapes and its deviations from ideal shape. The analysed results are obtained either by numerical simulation or by experiment. Finding the deviations generating mechanisms, it is possible to link dimensional, geometric and surface accuracy of workpiece to specific elements of technological system that is the significant point of the machine and tool design.

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Mat Taib, Zahrul Adnan, Wan Sharuzi Wan Harun, Saiful Anwar Che Ghani, Mohd Fadzil Faisae Ab Rashid, Mohd Asnawi Omar, and Hazlen Ramli. "Dimensional Accuracy Study of Open Cellular Structure CoCrMo Alloy Fabricated by Selective Laser Melting Process." Advanced Materials Research 1133 (January 2016): 280–84. http://dx.doi.org/10.4028/www.scientific.net/amr.1133.280.

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Designing orthodontic implants with desired physical and biological performances and to fabricate net shape with complex anatomical shapes is still a challenge. Cautious design approaches followed by systematic manufacturing techniques that can achieve balanced physical performance in mono block implants mechanics is necessary to accomplish this objective. Metal additive manufacturing (MAM) technique such as selective laser melting (SLM) process is progressively being utilized for new biomaterials such as cobalt-chrome-molybdenum (CoCrMo). This study was designed to determine a dimensional accuracy of open cellular structures CoCrMo samples with designing volume based porosity ranging between 0 % (full dense) to 80 %. A maximum 2.10 % shrinkage was obtained by 80 % designed porosity sample. Samples with higher volume-to-surface area (full dense) demonstrated the low total amount of shrinkage as compared to lower volume-to-surface area (80 % designed porosity).

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Vasiliev, Sergey, Viktor Alekseev, Mikhail Vasiliev, and Alyona Fedorova. "Development and Research of a Profile Recorder for Measuring Deviations in the Shape of the Surface of Products by Laser Spiral Scanning." Metal Working and Material Science 22, no. 4 (December 8, 2020): 71–81. http://dx.doi.org/10.17212/1994-6309-2020-22.4-71-81.

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Introduction. The paper deals with the development of a Profile recorder and measurement of deviations in the shape of the surface of products by laser spiral scanning. Analysis of the scientific literature shows that at present, the issues of monitoring and evaluating deviations in the shape of the surface of products require further research, since the use of well-known devices and methods does not always provide the necessary accuracy, manufacturability and sufficient information content of measurements. The research urgency is caused by the fact that existing methods of measuring form deviations of the surfaces does not allow to define a set of parameters with the required accuracy and submit it to two-dimensional and three-dimensional form. Objective: to develop a new method for evaluating a three-dimensional profile by implementing the method of laser spiral scanning and study the Profile recorder to improve the accuracy and productivity of measuring deviations in the shape of the product surface. Methods. The paper proposes a new method for evaluating a three-dimensional surface profile in order to directly determine the shape of the surface of products, to control the quality of the surface of products, regardless of its location. To implement the method, a Profile recorder of an original design is developed and investigated, which provides measurement of two parameters along the Archimedean spiral. Optimization of the design and the method of presenting information for measuring deviations in the shape of the surface of products are performed. Results and discussion. A method of statistical estimation of equations for describing the shape of metal surfaces based on the use of classical laws is proposed. In the case of a flat surface, deviations from flatness are evaluated: undulation, warping, twisting, convexity, concavity, curvature, etc. A Profile recorder is developed to implement the proposed method. The automated mechatronic device and the proposed method are tested on corrugated surfaces. Various equations obtained as a result of statistical processing were compared with each other, and the equation with the highest coefficient of determination is selected. The Profile recorder in Cartesian coordinates is studied in order to obtain reliable and accurate data for estimating shape deviations. The values of the deflection and the size of the corrugation along the height of the C-9 corrugated sheet are determined by laser spiral scanning.

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ZAIDI, QASIM, and ANDREA LI. "Three-dimensional shape perception from chromatic orientation flows." Visual Neuroscience 23, no. 3-4 (May 2006): 323–30. http://dx.doi.org/10.1017/s0952523806233170.

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The role of chromatic information in 3-D shape perception is controversial. We resolve this controversy by showing that chromatic orientation flows are sufficient for accurate perception of 3-D shape. Chromatic flows required less cone contrast to convey shape than did achromatic flows, thus ruling out luminance artifacts as a problem. Luminance artifacts were also ruled out by a protanope's inability to see 3-D shape from chromatic flows. Since chromatic orientation flows can only be extracted from retinal images by neurons that are responsive to color modulations and selective for orientation, the psychophysical results also resolve the controversy over the existence of such neurons. In addition, we show that identification of 3-D shapes from chromatic flows can be masked by luminance modulations, indicating that it is subserved by orientation-tuned neurons sensitive to both chromatic and luminance modulations.

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Zhao, Wen Cang, and Jun Bo Zhang. "CS-LBF Improved Model for 3D Medical Image Segmentation." Applied Mechanics and Materials 303-306 (February 2013): 2272–79. http://dx.doi.org/10.4028/www.scientific.net/amm.303-306.2272.

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This paper presents an algorithm for three-dimensional medical image segmentation based on the Contrast and Shape Constrained Local Binary Fitting improved model. Due to Local Binary Fitting model is sensitive to initialization and easy to fall into local extreme value, the new algorithm adds contrast constraint term to the Local Binary Fitting model, aiming at solving the common existed problem of inconsistent brightness and low contrast ratio. Adding shape constraint term can improve the original Local Binary Fitting model by constructing shape constraint energy field around the average shape by the level set method to deal with the leak of deformation curve. In order to promote the speed of model evolution, the kernel function is simplified. Two-dimensional Contrast and Shape Constrained Local Binary Fitting model is then extended to three-dimensional and a three-dimensional dental pulp image is segmented. Experimental results show that the segmentation accuracy, the connection degree and the efficiency of the new method are greatly improved compared to original LBF model.

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Jiang, Xiangjun, Fengqun Pan, Yesen Fan, Jingli Du, Mingbo Zhu, and Zhen Chen. "Active Adjustment of Surface Accuracy for a Large Cable-Net Structure by Shape Memory Alloy." Materials 12, no. 16 (August 16, 2019): 2619. http://dx.doi.org/10.3390/ma12162619.

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The high surface accuracy design of a cable-net antenna structure under the disturbance of the extremely harsh space environment requires the antenna to have good in-orbit adjustment ability for surface accuracy. A shape memory cable-net (SMC) structure is proposed in this paper and believed to be able to improve the in-orbit surface accuracy of the cable-net antenna. Firstly, the incremental stiffness equation of a one-dimensional bar element of the shape memory alloy (SMA) to express the relationship between the force, temperature and deformation was effectively constructed. Secondly, the finite element model of the SMC antenna structure incorporated the incremental stiffness equation of a SMA was established. Thirdly, a shape active adjustment procedure of surface accuracy based on the optimization method was presented. Finally, a numerical example of the shape memory cable net structure applied to the parabolic reflectors of space antennas was analyzed.

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Adamczak, Stanisław, Jacek Świderski, and Tomasz Dobrowolski. "Evaluation of the dimensional-shape accuracy and surface stereometry of the radiator formed by precision VHM." Mechanik 90, no. 10 (October 9, 2017): 918–20. http://dx.doi.org/10.17814/mechanik.2017.10.147.

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The paper presents the possibilites of aplication the individual measurement methods for evaluation of the dimensional-shape accuracy and surface stereometry of the radiator milled with precision VHM with DLC coating.

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OLIVEIRA, SERGIO A., MARCELO A. SAVI, and ILMAR F. SANTOS. "UNCERTAINTY ANALYSIS OF A ONE-DIMENSIONAL CONSTITUTIVE MODEL FOR SHAPE MEMORY ALLOY THERMOMECHANICAL DESCRIPTION." International Journal of Applied Mechanics 06, no. 06 (December 2014): 1450067. http://dx.doi.org/10.1142/s1758825114500677.

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The use of shape memory alloys (SMAs) in engineering applications has increased the interest of the accuracy analysis of their thermomechanical description. This work presents an uncertainty analysis related to experimental tensile tests conducted with shape memory alloy wires. Experimental data are compared with numerical simulations obtained from a constitutive model with internal constraints employed to describe the thermomechanical behavior of SMAs. The idea is to evaluate if the numerical simulations are within the uncertainty range of the experimental data. Parametric analysis is also developed showing the most sensitive constitutive parameters that contribute to the uncertainty. This analysis provides the contribution of each parameter establishing the accuracy of the constitutive equations.

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Xie, Shundao, and Hong-Zhou Tan. "Blur-readable two-dimensional barcode based on blur-invariant shape and geometric features." International Journal of Advanced Robotic Systems 18, no. 2 (March 1, 2021): 172988142199958. http://dx.doi.org/10.1177/1729881421999589.

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In recent years, the application of two-dimensional (2D) barcode is more and more extensive and has been used as landmarks for robots to detect and peruse the information. However, it is hard to obtain a sharp 2D barcode image because of the moving robot, and the common solution is to deblur the blurry image before decoding the barcode. Image deblurring is an ill-posed problem, where ringing artifacts are commonly presented in the deblurred image, which causes the increase of decoding time and the limited improvement of decoding accuracy. In this article, a novel approach is proposed using blur-invariant shape and geometric features to make a blur-readable (BR) 2D barcode, which can be directly decoded even when seriously blurred. The finder patterns of BR code consist of two concentric rings and five disjoint disks, whose centroids form two triangles. The outer edges of the concentric rings can be regarded as blur-invariant shapes, which enable BR code to be quickly located even in a blurred image. The inner angles of the triangle are of blur-invariant geometric features, which can be used to store the format information of BR code. When suffering from severe defocus blur, the BR code can not only reduce the decoding time by skipping the deblurring process but also improve the decoding accuracy. With the defocus blur described by circular disk point-spread function, simulation results verify the performance of blur-invariant shape and the performance of BR code under blurred image situation.

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Pan, Xiang, and Ying Cui. "Semantic isometry for 3-D shape correspondence." International Journal of Advanced Robotic Systems 15, no. 1 (January 1, 2018): 172988141775080. http://dx.doi.org/10.1177/1729881417750805.

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Isometry has been widely used in corresponding problem with pose variation. However, most existing methods are causing wrong correspondences due to the ambiguity of geodesic distance. This article introduces the semantic isometry to three-dimensional shape correspondence and proposes a new framework called detection–recognition–correspondence. The idea of semantic isometry is to embed the semantic information and statistical learning through sparse correspondence for better performance. Feature point detection is first utilized to extract the salient feature point of the three-dimensional shapes. Then, instead of finding correspondence pairs directly by minimizing the isometric error of the detected feature points, the semantic labels of these feature points are recognized using the support vector machine. The semantic label is used to perform a priority-driven isometric correspondence.The highly reliable corresponding pairs are then obtained to serve as the further constraint in the following corresponding process. During the experiments, the robustness of the proposed algorithm is verified by different kinds of three-dimensional dynamic models, including some very challenging data with pose variation and missing parts. Moreover, the proposed framework can greatly improve the corresponding accuracy over the existing state-of-the-art algorithms.

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Oh, Il Yeong, Sang Wook Han, Young Yun Woo, Jae Hyeon Ra, and Young Hoon Moon. "Process Analysis of Fabricating Elbow Tubes by Mandrel Bending Process." Materials Science Forum 920 (April 2018): 40–45. http://dx.doi.org/10.4028/www.scientific.net/msf.920.40.

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The process of tube bending involves using mechanical force to push stock material pipe or tubing against a die, forcing the pipe or tube to conform to the shape of the die. For some tube bending processing, a mandrel is placed inside the tube to prevent collapsing. In this study, the elbow bending process using mandrel has been investigated to fabricate precise elbow-shaped tubes. To fabricate tube having target shape within the dimensional tolerance, the process analysis has been performed at various processing parameters such as tube dimensions, tilting angles, curved cutting surface and the radius of curvature. To estimate the dimensional accuracies of formed tubes, the standard deviations of dimensional errors between target and formed tubes have been used as a quantitative index. Results show that the elbow tube having larger radius of curvature shows higher dimensional accuracy due to the relatively uniform strain distribution. And the convex cutting surface is desirable to increase contacts between the punch and the tube ends during the bending process.

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Xiuda, Zhang, Yan Huimin, and Jiang Yanbing. "Pulse-shape-free method for long-range three-dimensional active imaging with high linear accuracy." Optics Letters 33, no. 11 (May 28, 2008): 1219. http://dx.doi.org/10.1364/ol.33.001219.

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Journal articles on the topic 'Dimensional and shape accuracy'

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