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Posts Tagged ‘COMPUTER-aided design’

A simple cad method for constructing sand-heap formations as an analogous means of determining the fully plastic torque capacity of various structural sections






A brief review is presented of the sand-heap analogy as a means of determining the ultimate plastic torque capacity of a ductile metallic prismatic bar of known cross-section. A novel method using an industry-standard computer-aided design (CAD) tool is then described for determining the shape and corresponding sand-heap volume for a general cross-section that can include the presence of keyways, fillets, rebates, and holes. Existing solutions for simple regular cross-section shapes are used as a benchmark for the solutions from the new method, and perfect agreement is found. Subsequent examples are presented which demonstrate the ease with which sand-heap formations and their corresponding volumes can be found for more general cross-sections that are more representative of those used in practical engineering applications. [ABSTRACT FROM AUTHOR]


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A weighted bivariate blending rational interpolation function and visualization control

A new weighted bivariate blending rational spline with parameters is constructed based on function values of a function only. The interpolation is C¹ in the whole interpolating region under the condition which free parameters is not limited. This paper deals with the properties of the interpolation surface, including the properties of basis function, the properties of integral weighted coefficients and bounded property of the interpolation. In order to meet the needs of practical design, an interpolation technique is employed to control the shape of surfaces. The method of value control of the interpolation at any point in the interpolating region is developed. This control method can be applied to modify the local shape of an interpolating surface by selecting suitable parameters simply. [ABSTRACT FROM AUTHOR]

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Microstructure morphology and performance characteristics of a nickel-based alloy part fabricated by laser metal deposition shaping

Laser metal deposition shaping (LMDS) is a new rapid manufacturing technology, which involves computer aided design, laser processing, material science and numerical control machining. This advanced technology can build fully-dense metal components directly from computer aided design (CAD) files without any mould or tool. In order to master the microstructure morphology and property features of as-formed metal parts, a kind of nickel-based alloy powder was selected to perform this experiment. Typically, the thin-wall part was manufactured with single-pass and multi-layer depositing process. Then, the metallographic samples and tensile specimens were cut out from the thin-wall part for analyzing material characteristics. The results show that there are different grain categories distributing in certain vertical position of thin-wall part, which depends on both temperature gradient and solidification rate at the solid/liquid interface. Furthermore, influenced by the microstructure distributing features of as-deposited component, the mechanical properties represent as anisotropy. [ABSTRACT FROM AUTHOR]

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Automatic segmentation of dermoscopy images using histogram thresholding on optimal color channels

Automatic segmentation of skin lesions is the first step towards development of a computer-aided diagnosis of melanoma. Although numerous segmentation methods have been developed, few studies have focused on determining the most discriminative and effective color space for melanoma application. This paper proposes a novel automatic segmentation algorithm using color space analysis and clustering-based histogram thresholding, which is able to determine the optimal color channel for segmentation of skin lesions. To demonstrate the validity of the algorithm, it is tested on a set of 30 high resolution dermoscopy images and a comprehensive evaluation of the results is provided, where borders manually drawn by four dermatologists, are compared to automated borders detected by the proposed algorithm. The evaluation is carried out by applying three previously used metrics of accuracy, sensitivity, and specificity and a new metric of similarity. Through ROC analysis and ranking the metrics, it is shown that the best results are obtained with the X and XoYoR color channels which results in an accuracy of approximately 97%. The proposed method is also compared with two state-of the- art skin lesion segmentation methods, which demonstrates the effectiveness and superiority of the proposed segmentation method. [ABSTRACT FROM AUTHOR]

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