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Physically based simulation of human hair is a well studied and well known problem. But the “pure” physically based representation of hair (and other animation elements) is not the only concern of the animators, who want to “control” the creation and animation phases of the content. This paper describes a sketch-based tool, with which a user can both create hair models with different styling parameters and produce animations of these created hair models using physically and key frame-based techniques. The model creation and animation production tasks are all performed with direct manipulation techniques in real-time. 相似文献
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The noise of aerodynamics nature from modern transonic fan is examined from its sources with the perspective of noise reduction through aero-acoustics design using advanced Computational Fluid Dynamics (CFD) tools. In particular the problems associated with the forward propagating noise in the front is addressed. It is identified that the shock wave spillage from the leading edge near the fan tip is the main source of the tone noise. Two different approaches have been studied to reduce the forward arc tone noise and two state-of-art transonic fans are designed using the strategies developed. The following rig tests show that while the fans exhibit other noise problems, the primary goals of noise reduction have been achieved through both fans and the novel noise reduction concept vindicated. 相似文献
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SARs are cis DNA elements of chromosome dynamics: synthesis of a SAR repressor protein 总被引:1,自引:0,他引:1
SARs are candidate DNA elements for defining the bases of chromatin loops and possibly for serving as cis elements of chromosome dynamics. SARs contain numerous A tracts, whose altered DNA structure is recognized by cooperatively interacting proteins such as topoisomerase II. We constructed multi-AT hook (MATH) proteins and demonstrate that they specifically bind the clustered A tracts of SARs in chromatin and chromosomes. They are also potent inhibitors of chromosome assembly in mitotic Xenopus extracts, demonstrating the importance of SARs in this process. Titration of SARs with MATH20 (20 hooks) blocks shape determination of chromatids but not chromatin condensation per se. SARs are also required for shape maintenance of chromosomes. If MATH20 is added after formation of chromatids, they collapse and are reshaped by an active, mitotic process into spherical chromatid balls. 相似文献
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Endocrine and exocrine pancreatic morphogenesis is known to occur from ductal epithelium, but the factors that regulate this process are unknown. Vascular endothelial growth factor (VEGF)/vascular permeability factor has recently been reported to affect fetal islet ontogenesis. VEGF is an angiogenic factor with a growth-promoting effect that is thought to be restricted to vascular endothelial cells. We demonstrated that VEGF is also a mitogen for adult rat pancreatic duct epithelial cells in primary culture. VEGF supplementation to a serum-free culture medium increased the 5-bromo-2'-deoxyuridine-pulse labeling index of ductal cells more than 2-fold. Immunohistochemical staining and protein blots revealed that pancreatic duct cells express fetal liver kinase-1 high-affinity receptors for VEGF. In pancreatic tissue, immunohistochemistry shows that VEGF peptide is expressed in normal pancreatic islet cells. In duct ligation-induced acute pancreatitis, numerous inflammatory leukocytes containing VEGF were seen to infiltrate between hyperplastic ducts. In the latter model, islet neogenesis has previously been observed. Our data indicate the possibility that VEGF plays a role in the paracrine regulation of ductal growth and differentiation in vivo, eg, in pancreatitis. In vitro, however, VEGF did not induce endocrine differentiation of ductal cells, indicating that it is not the only factor required for the activation of islet neogenesis. 相似文献
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Conventional constant false alarm rate (CFAR) methods use a fixed number of cells to estimate the background variance. For homogeneous environments, it is desirable to increase the number of cells, at the cost of increased computation and memory requirements, in order to improve the estimation performance. For nonhomogeneous environments, it is desirable to use less number of cells in order to reduce the number of false alarms around the clutter edges. In this work, we present a solution with two exponential smoothers (first order IIR filters) having different time-constants to leverage the conflicting requirements of homogeneous and nonhomogeneous environments. The system is designed to use the filter having the large time-constant in homogeneous environments and to promptly switch to the filter having the small time constant once a clutter edge is encountered. The main advantages of proposed Switching IIR CFAR method are computational simplicity, small memory requirement (in comparison to windowing based methods) and its good performance in homogeneous environments (due to the large time-constant smoother) and rapid adaptation to clutter edges (due to the small time-constant smoother). 相似文献
9.
Jianu R Demiralp Ç Laidlaw DH 《IEEE transactions on visualization and computer graphics》2012,18(6):978-987
We introduce two-dimensional neural maps for exploring connectivity in the brain. For this, we create standard streamtube models from diffusion-weighted brain imaging data sets along with neural paths hierarchically projected into the plane. These planar neural maps combine desirable properties of low-dimensional representations, such as visual clarity and ease of tract-of-interest selection, with the anatomical familiarity of 3D brain models and planar sectional views. We distribute this type of visualization both in a traditional stand-alone interactive application and as a novel, lightweight web-accessible system. The web interface integrates precomputed neural-path representations into a geographical digital-maps framework with associated labels, metrics, statistics, and linkouts. Anecdotal and quantitative comparisons of the present method with a recently proposed 2D point representation suggest that our representation is more intuitive and easier to use and learn. Similarly, users are faster and more accurate in selecting bundles using the 2D path representation than the 2D point representation. Finally, expert feedback on the web interface suggests that it can be useful for collaboration as well as quick exploration of data. 相似文献
10.
Keith D. Bartle Ayla Çalimli Derry W. Jones Raymond S. Matthews Aral Olcay Hooshang Pakdel Taner Tuǧrul 《Fuel》1979,58(6):423-428
Fractions of Elbistan and Seyitomer (Turkish) lignites, extracted with supercritical toluene at 340 °C and 8 MPa, have been separated by solvent extraction and silica-gel chromatography. Analyses by n.m.r. and i.r. spectroscopies and other methods have been combined in structural-analysis schemes to yield information about the average molecule in aromatic extracts. Carbon aromaticities, fa, derived from 22.63 MHz 1H-decoupled pulse Fourier-transform (PFT) 13C-n.m.r. are more widely spread for Elbistan (0.34–0.56) than for Seyitomer (0.40–0.43), and are lower than for supercritical-gas (SCG) products from bituminous coals. 13C-n.m.r. also reveals the presence of aromatic ether-O in polar fractions. Narrow aromatic signals in 100 MHz 1H-n.m.r. spectra suggest the presence of single-aromatic-ring average structures. In the hexane-soluble aromatics, 27% (Elbistan) and 29% (Seyitomer) of the available sites are substituted by alkyI groups, some of which are at least eight carbon atoms long; the hexane-soluble polar and asphaltene/asphaltol fractions contain fewer such groups. 相似文献