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81.
3D shape metamorphosis based on T-spline level sets 总被引:1,自引:0,他引:1
We propose a new method for 3D shape metamorphosis, where the in-between objects are constructed by using T-spline scalar
functions. The use of T-spline level sets offers several advantages: First, it is convenient to handle complex topology changes
without the need of model parameterization. Second, the constructed objects are smooth (C2 in our case). Third, high quality meshes can be easily obtained by using the marching triangulation method. Fourth, the distribution
of the degrees of freedom can be adapted to the geometry of the object.
Given one source object and one target object, we firstly find a global coordinate transformation to approximately align the
two objects. The T-spline control grid is adaptively generated according to the geometry of the aligned objects, and the initial
T-spline level set is found by approximating the signed distance function of the source object. Then we use an evolution process,
which is governed by a combination of the signed distance function of the target object and a curvature-dependent speed function,
to deform the T-spline level set until it converges to the target shape. Additional intermediate objects are inserted at the
beginning/end of the sequence of generated T-spline level sets, by gradually projecting the source/target object to the initial/final
T-spline level set. A fully automatic algorithm is developed for the above procedures. Experimental results are presented
to demonstrate the effectiveness of our method. 相似文献
82.
Careful combination of a metal compound,a ligand and an inorganic support material leads to supramolecular catalysts that mimic the structural, organizational and functional aspects of enzyme activity.After discussing essential features of metalloenzyme-catalyzed reactions and coordination chemistry in inorganic hosts, we present examples of supramolecular materials selected from our own work that eventually resulted in useful catalysts for organic transformations in the liquid phase. 相似文献
83.
Graphene sheets can be regarded as base structure of many carbon nanostructures, and atomic arrangements and variations in the atomic structure have a drastic impact on their unique properties. Using a single/double layer graphene model structure, we present a strategy to “see” single carbon atoms in 3-D. In high-resolution transmission electron microscopy, exit-wave images are essential to obtain and to understand 3-D atomic structure. Using electrons at 80 kV not only minimizes the knock-on damage, but also improves the detection sensitivity due to the higher scattering power of carbon at lower acceleration voltage of the electron. Using experiments and image simulations, positions of individual carbon atoms in a single/double layer structure in graphene have been identified. 相似文献
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85.
86.
Hybrid processes in manufacturing 总被引:2,自引:0,他引:2
Bert Lauwers Fritz Klocke Andreas Klink A. Erman Tekkaya Reimund Neugebauer Don Mcintosh 《CIRP Annals》2014,63(2):561-583
87.
88.
Modeling capabilities for longitudinal data have progressed considerably, but questions remain on the extent to which method bias may negatively affect the validity of longitudinal survey data. The current study addresses the stability of individual response styles. We set up a longitudinal data collection in which the same respondents filled out 2 online questionnaires with nonoverlapping sets of heterogeneous items. Between data collections, there was a 1-year time gap. We simultaneously modeled 4 response styles that capture the major directional biases in questionnaire responses: acquiescence, disacquiescence, midpoint, and extreme response style. Drawing from latent state–trait theory, we specified a 2nd-order factor model with time-invariant and time-specific response style factors and a specifically designed covariance structure for the residual terms. The results indicate that response styles have an important stable component, a small part of which can be explained by demographics. The meaning and implications of these findings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
89.
Global learning on carbon capture and storage: A call for strong international cooperation on CCS demonstration 总被引:1,自引:0,他引:1
Closing the gap between carbon dioxide capture and storage (CCS) rhetoric and technical progress is critically important to global climate mitigation efforts. Developing strong international cooperation on CCS demonstration with global coordination, transparency, cost-sharing and communication as guiding principles would facilitate efficient and cost-effective collaborative global learning on CCS, would allow for improved understanding of the global capacity and applicability of CCS, and would strengthen global trust, awareness and public confidence in the technology. 相似文献
90.
In a household survey in Guinea-Bissau, 319 episodes of diarrhea in children were followed by interviews every second day with the aim of investigating perceived morbidity and subsequent actions taken. The majority of the mothers had good knowledge of oral rehydration salts (ORS). However, only 58% of the episodes were treated with ORS and the amount given was insufficient. Mothers with no knowledge of ORS did not use it during the observed attack of diarrhea regardless of contact with a health center, which suggests that maternal knowledge is an important determinant of whether health personnel provide ORS. Children with diarrhea considered to be caused by teething were less likely to receive ORS in the acute phase (risk ratio = 0.6, 95% confidence interval [CI] = 0.5-0.9). Univariate analyses showed that the use of ORS was related to number of reported symptoms, the mother being the care taker, consultations, previous use of ORS, good knowledge of ORS, and having ORS sachets at home. Multivariate Cox regression analyses showed that the presence of ORS sachets at home at the onset of diarrhea was the strongest predictor of use (hazard ratio = 3.3, 95% CI = 1.9-3.6). Improved health education should focus more on the quantity of ORS needed, early signs of dehydration, treatment of teething diarrhea, and breast feeding, and address mothers who have no prior knowledge of ORS. Management of diarrhea may be improved by a more liberal distribution of ORS sachets. 相似文献