We present a new sketch-basedmodeling approach in which models are interactively designed by drawing their 2d silhouettes from different views. The core idea of our paper is to limit the input to 2d silhouettes, remo...
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We present a new sketch-basedmodeling approach in which models are interactively designed by drawing their 2d silhouettes from different views. The core idea of our paper is to limit the input to 2d silhouettes, removing the need to explicitly create or position 3d elements. Arbitrarily complex models can be constructed by assembling them out of parts defined by their silhouettes, which can be combined using CSG operations. We introduce a new simplified algorithm to compute CSG solids that leverages special properties of silhouette cylinders to convert the 3d CSG problem into one that can be handled entirely with 2d operations, making implementation simpler and more robust. We evaluate our approach by modeling a random sampling of man-made objects taken from the words in WordNet, and show that all of the tested man-made objects can be modeled quickly and easily using our approach.
In the process of rapid prototyping by the method of selective laser sintering (SLS), transient temperature has direct effect upon the sintering performance. In the present work, a model is developed in order to gener...
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In the process of rapid prototyping by the method of selective laser sintering (SLS), transient temperature has direct effect upon the sintering performance. In the present work, a model is developed in order to generate 3d transient temperature field. It uses Al2O3 coated ceramic powder and involves the finite element method (FEM) variation of thermal properties and solid-liquid two-phase interface. A highspeed charge coupleddevice (CCd) image temperature measurement system is used to generate for testing. The obtained test results validates the simulation data and implies that the proposedmodeling method is useful in simulating the transient sintering temperature specially when the correct thermal properties and key factors of two-phase interface are main concerns. The performance characteristics of the reasonable sintering parameters are predicted by the proposedmodeling method. (C) 2011 Elsevier GmbH. All rights reserved.
In this research, a sawing mechanism of a mobile buckling machine was innovatively designed for the forest resources and environmental characteristics of the northeast region of China. The northeast region of China is...
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In this research, a sawing mechanism of a mobile buckling machine was innovatively designed for the forest resources and environmental characteristics of the northeast region of China. The northeast region of China is rich in forest resources, but the climate is cold, which puts high demands on the performance and adaptability of mechanical equipment. In this study, the three-dimensional modeling of the saw-cutting mechanism was completed by Pro/Engineer 5.0 modeling software, and an in-depth dynamics simulation analysis was carried out using dynamics simulation software. The study aims to assess the applicability of this saw-cutting mechanism in the northeast region of China, analyze its design characteristics, and explore possible directions for performance optimization. Through this study, we expect to provide valuable references for future technological innovations, as well as to promote the practical application anddevelopment of mobile buckling machines in cold regions. This research not only has regional characteristics, but also reflects the innovative idea of combining mechanical equipment design with environmental adaptability.
Understanding the soil heat and moisture transport is significant for assessing the living condition of vegetation and microorganisms in soils. Numerous studies have been conducted to understand the coupled soil heat ...
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Understanding the soil heat and moisture transport is significant for assessing the living condition of vegetation and microorganisms in soils. Numerous studies have been conducted to understand the coupled soil heat and moisture transport under "normal" environmental conditions;while this coupled transport under extremely high-temperature conditions caused by surface wildfires is little understood. Particularly, 3d modeling of such coupled transport is absent. Here, we develop a 3d model to understand more realistic characteristics of the soil heat and moisture transport beneath a surface fire. With the 3d model, we investigate the lateral transport of soil heat and moisture in a 3d space, the influence of a surface fire on soil moisture and temperature conditions in neighboring regions without fires, and the effect of initial water contents on the delay of soil heating. The modeling results showed that the lateral transport leads to an obvious difference in soil temperature and moisture between the inside and border area of the fire region. Such a difference cannot be considered with a 1d model widely used in existing studies. For the initial water content effect, we confirmed that a high initial water content delays the soil heating to cooler regions at deeper soil depths during the late stage of soil heating. Our results also showed that a surface fire significantly changes soil heat and moisture in the no-fire region neighboring to the simulated fire. At the location 50 m away from the fire region, the soil temperature and moisture in upper soil layers can increase to over 85 degrees C anddecrease to 0.006 m(3) m(-3) within 5 h, respectively. This study provides important insights, which are useful for fire management but have not been reported before, for understanding more physically realistic characteristics of the 3d soil heat and moisture transport beneath a surface fire in both the fire and no-fire regions. (C) 2019 Elsevier Ltd. All rights reserved.
The knowledge of the 3d geometry for reverse engineering studies is based on images and/or distances. The use of scanner laser has replaced the photogrammetry in the last decade, due to its easy handling and intensive...
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The knowledge of the 3d geometry for reverse engineering studies is based on images and/or distances. The use of scanner laser has replaced the photogrammetry in the last decade, due to its easy handling and intensive data provided. However it requires multiple data captures, a subsequent filtering and a complex data processing, and its accuracy is highly dependent on the material. These limitations mean that many times it will not be the best option (in addition to its high cost). The videogrammetry is capable of generating a high number of images (which implies a high number of points) in a shorter time and regardless of the type of material. This paper analyses the accuracy of a new videogrammetric system respect to two scanner lasers. Results obtained certify that videogrammetry reaches similar accuracy than EScan (high resolution portable 3d scanner for reverse engineering), and higher accuracy than architectural scanner laser. In both cases the time spent in the 3d model generation by means of videogrammetry results much lower and the process is completely automatic requiring no post-processing or filtering work. Finally videogrammetry also enables real 3d object visualization through anaglyphs in all desired positions, while laser systems cannot provide that kind of information. (C) 2016 Elsevier Ltd. All rights reserved.
Unconformity-related uranium deposits are the highest grade, large tonnage uranium resources in the world. In the Athabasca Basin (northern Saskatchewan, Canada), which is the premier host for unconformity-type deposi...
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Unconformity-related uranium deposits are the highest grade, large tonnage uranium resources in the world. In the Athabasca Basin (northern Saskatchewan, Canada), which is the premier host for unconformity-type deposits, the ore deposits are frequently hosted and surrounded by breccias in sandstone. The significance of these breccias and their relation to mineralization are of major importance for the genesis of these high-grade deposits. Therefore, a modeling study, integrating results from structural geology and petrology, was performed with the gOcad3d modeling software, in order to decipher geometrical and geological relationships between breccias, faults and mineralization zones. Mineralized bodies and the sudoite-dravite breccia bodies display strong spatial correlations. They appear to be controlled by reverse shear zones cross-cutting the unconformity and containing graphite in the basement. Geochemical computations evidenced that volumetric water-rock ratios up to 10,000 could be obtained in these breccia bodies for volume losses of up to 90%. Assuming reasonable values for quartz saturation, hydraulic conductivity and connected porosity, the minimal fluid volume and the time duration necessary to generate the sudoite-dravite breccia bodies were estimated at ca. 2 km(3) and ca. 1 Myr, respectively. The comparison of these results with literature data suggests that the formation of sudoite-dravite breccia and mineralization could have been coeval. It may be proposed that within the space created by the quartz dissolution in the breccia body, a mixing between basement and basinal fluids could have induced U deposition and allowed the development of high-grade mineralization. The first-order uranium solubility that this coeval formation would imply is consistent with literature data, which suggests that this conceptual model is reasonable. (C) 2007 Elsevier Ltd. All rights reserved.
A method to model the left ventricular myocardium in thallium-201 Single Photon Emission Computed Tomography (SPECT) is presented. This method is based on the fitting of the morphological skeleton of the left ventricl...
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A method to model the left ventricular myocardium in thallium-201 Single Photon Emission Computed Tomography (SPECT) is presented. This method is based on the fitting of the morphological skeleton of the left ventricle to a truncated bullet. This automatic approach would provide a more reproducible visualization of the organ for clinical applications.
Reconstructing 3d models given a single-view 2d information is inherently an ill-posed problem and requires additional information such as shape prior or user input. We introduce a method to generate multiple 3d model...
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Reconstructing 3d models given a single-view 2d information is inherently an ill-posed problem and requires additional information such as shape prior or user input. We introduce a method to generate multiple 3d models of a particular category given corresponding photographs when the topological information is known. While there is a wide range of shapes for an object of a particular category, the basic topology usually remains constant. In consequence, the topological prior needs to be provided only once for each category and can be easily acquired by consulting an existing database of 3d models or by user input. The input of topological description is only connectivity information between parts;this is in contrast to previous approaches that have required users to interactively mark individual parts. Given the silhouette of an object and the topology, our system automatically finds a skeleton and generates a textured3d model by jointly fitting multiple parts. The proposed method, therefore, opens the possibility of generating a large number of 3d models by consulting a massive number of photographs. We demonstrate examples of the topological prior and reconstructed3d models using photos.
Numerical models for simulating volcanic debris avalanches commonly lack a critical initiation parameter, the source volume, which is difficult to estimate without data on the deposit thickness. This, in turn, limits ...
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Numerical models for simulating volcanic debris avalanches commonly lack a critical initiation parameter, the source volume, which is difficult to estimate without data on the deposit thickness. This, in turn, limits how rheology can be characterized for simulating flow. Leapfrog Geo, a 3d geological modeling software, was used to integrate shallow-seismic reflection profiles with field and borehole data to determine the volume of the Buhi debris avalanche and the pre-collapse structure of Iriga Volcano. Volumes of the deposit calculated in this way are 34-71% larger than previous estimates. This technique may improve models of debris avalanches elsewhere in the world, and more precisely depict landslide runout and lateral extent, thus improving disaster prevention and mitigation for the many cities located near volcanoes. (C) 2016 Elsevier B.V. All rights reserved.
The mathematical characterization of the sound of a musical instrument still follows Schumann's laws (Schumann in Physik der klangfarben, Leipzig, 1929). According to this theory, the resonances of the instrument ...
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The mathematical characterization of the sound of a musical instrument still follows Schumann's laws (Schumann in Physik der klangfarben, Leipzig, 1929). According to this theory, the resonances of the instrument body, "the formants", filter the oscillations of the sound generator (e.g., strings) and produce the characteristic "timbre" of an instrument. This is a strong simplification of the actual situation. It applies to a point source and can be easily performed by a loudspeaker, disregarding the three dimensional structure of music instruments. To describe the effect of geometry and material of the instruments, we set up a 3d model and simulate it using the simulation system UG4 (Vogel et al. in Comput Vis Sci 16(4):165-179, 2013;Reiter et al. in Comput Vis Sci 16(4):151-164, 2014). We aim to capture the oscillation behavior of eigenfrequencies of a harpsichord soundboard and investigate how well a model for the oscillation behavior of the soundboard approximates the oscillation behavior of the whole instrument. We resolve the complicated geometry by several unstructured3d grids and take into account the anisotropy of wood. The oscillation behavior of the soundboard is modeled following the laws of linear orthotropic elasticity with homogenous boundary conditions. The associated eigenproblem is discretized using FEM and solved with the iterative PINVIT method using an efficient GMG preconditioner (Neymeyr in A hierarchy of preconditioned eigensolvers for elliptic differential operators. Habilitation dissertation, University of Tubingen, 2001). The latter allows us to resolve the harpsichord with a high resolution hybrid grid, which is required to capture fine modes of the simulated eigenfrequencies. We computed the first 16 eigenmodes and eigenfrequencies with a resolution of 1.8 billion unknowns each on Shaheen II supercomputer (). To verify our results, we compare them with measurement data obtained from an experimental modal analysis of a real reference harp
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