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101.
We show that the wavefront approach to Voronoi diagrams (a deterministic line-sweep algorithm that does not use geometric
transform) can be generalized to distance measures more general than the Euclidean metric. In fact, we provide the first worst-case
optimal (O (n logn) time,O(n) space) algorithm that is valid for the full class of what has been callednice metrics in the plane. This also solves the previously open problem of providing anO (nlogn)-time plane-sweep algorithm for arbitraryL
k
-metrics. Nice metrics include all convex distance functions but also distance measures like the Moscow metric, and composed
metrics. The algorithm is conceptually simple, but it copes with all possible deformations of the diagram.
Research partially supported by the Natural Sciences and Engineering Research Council of Canada.
Research partially supported by the Deutsche Forschungsgemeinschaft, Grant No. Kl 655/2-1. 相似文献
102.
State of the art multiresolution modeling allows to selectively refine a coarse mesh of an object on the visually important parts. In this way it is possible to render the geometry of a given object accurately with a minimum number of triangles. The criteria used in current approaches take care of geometric error and even of shading errors. If however texture mapping is used it is inevitable to control displacements and distortions of the texture during refinements. 相似文献
103.
Fabrication of high aspect ratio structures requires the use of a photoresist able to form a mold with vertical sidewalls.
Thus the photoresist should have a high selectivity between the exposed and the unexposed area in the developer. It should
be relatively free from stress when applied in thick layers necessary to make high aspect ratio structures. PMMA (Poly Methyl
Methacrylate) is the photoresist of choice in the LIGA process, mainly for its ability to hold vertical sidewalls for tall
structures. It is applied to the substrate by a glue-down process in which a pre-cast, high molecular weight, sheet of PMMA
is attached to the plating base on a substrate. The applied photoresist is then milled down to the precise height by a fly-cutter
prior to pattern transfer by x-ray exposure. The requirement that the applied layer be relatively free from stress dictates
the choice of glue-down over casting. The substrate preparation steps, as well as the conditioning of the PMMA sheet prior
to the glue-down, are done, in part, to reduce the stress in the glued down sheet of photoresist. The cutting of the PMMA
sheet in the fly-cutter requires specific operating conditions as well as particular cutting tools to avoid introducing any
stress and the resultant crazing of the photoresist.
Received: 25 August 1997/Accepted: 3 September 1997 相似文献
104.
Outstanding features favour the application of polymers and polymer composites in low-temperature technology. The booming hydrogen technology is a challenge for these materials, which are considered as seals and bearings in cryogenic pumps. In the present study, three types of thermoplastics, i.e., polyetheretherketone (PEEK), polyetherimide (PEI) and polyamide 6,6 (PA6,6), and one epoxy were considered as matrix materials. Micron-sized fillers, i.e., short carbon fibres, graphite flakes, and PTFE powders, were incorporated into these polymers together with nano-sized TiO2 particles. Optimised compositions of each matrix were selected from our previous works at room temperature in order to be studied at very low temperature conditions. In particular, frictional tests were carried out with polymer composite pins against polished steel surfaces under constant load over a certain distance in liquid hydrogen and liquid nitrogen. Afterwards, worn surfaces were analysed by using scanning electron microscopy (SEM). It was found out that the tribological properties in liquid hydrogen are dominated by the matrix materials, in particular thermoplastics perform generally slightly better than thermosetting resins. 相似文献
105.
A method for solvent screening and searching for additives in the field of physical absorption processes is presented. A model based on the concept of virtual components and on the concept of a simplified abstract flow sheet is created. An estimation procedure for thermodynamically consistent property sets for the virtual component is developed. The model is implemented into MATLAB®. Its application is demonstrated in two studies including a study for a solvent additive. Potential candidates can be characterized and ranges for properties of the solvent or additive are found by means of the model. Conclusions obtained from the model support the screening process by a reduction of the number of further investigated components. 相似文献
106.
Clotilde Muller Sandrine Muller Aicha Sissoko Alexandre Klein Bernadette Faller Francois Chantrel 《Hemodialysis international. International Symposium on Home Hemodialysis》2012,16(4):556-558
Lanthanum therapy is an efficient therapy of hyperphosphoremia by chelating phosphore in the digestive tract. Lanthanum is a silvery white metallic element that belongs to group 3 of the periodic table. This drug is lightly absorbed and has low water solubility. It should be borne in mind that abdominal X‐rays of patients taking lanthanum carbonate may have a radio‐opaque appearance typical of imaging agents. This characteristic is suggested to confirm adherence of the patient by doing an abdominal X‐ray. We describe in our case a particular good compliant patient with slow digestive transit, which ends by pseudo‐occlusion. 相似文献
107.
I. S. Bersenev V. I. Klein P. I. Zarshchikov N. A. Osokin V. N. Shcheglov 《Steel in Translation》2013,43(4):193-196
The production of lime by bed roasting in a MAK-90 sintering machine is considered. The thermal and material balances of the process are analyzed. The thermal system of the sintering machine is modernized so as to permit lime production, with reduction in the power consumption and considerable decrease in dust emission. 相似文献
108.
Abstract We present molecular dynamics simulations examining the effect of the interatomic potential on steady‐state mode I crack propagation in a two‐dimensional triangular lattice as a function of applied strain. The interatomic potential is the Morse potential whose failure strain exhibits linear variation with its exponential parameter. The limiting crack speed is defined to be the steady‐state crack velocity observed at the onset of instability in steady‐state crack propagation leading to dislocation nucleation or crack branching. For all systems studied, the limiting crack speed is observed to be less than one third the Rayleigh wave speed. The fastest crack propagation in these ideal systems is associated with a material's long‐wavelength elastic properties being dominated by the strength of the nearest‐neighbor bond. 相似文献
109.
The influence of ozonization on the composition and flotation properties of spent motor oil is investigated. Preliminary ozonization increases the proportion of low-boiling components in the spent oil, reduces its viscosity, and improves its flotation properties in the enrichment of coking coal. 相似文献
110.
Alexandru T. Balaban William A. Seitz Douglas J. Klein 《Fullerenes, Nanotubes and Carbon Nanostructures》2013,21(3):467-476
Abstract Three “onion type” double carbon cages (consisting of an inner sp3-hybridized C60 buckminsterfullerene skeleton and an outer larger carbon cage with icosahedral symmetry, with covalent bonds between the carbon atoms of the 5-membered rings) are described and their strain energies are discussed: (i) when the outer cage is a C120 cage derived from buckminsterfullerene by replacing each bond between two six-membered rings by an acetylenic group, the strain is smallest.; (ii) when the same derivation concerns each bond between 5- and 6-membered rings leading to a C180 outer cage, the strain is largest.; (iii) when the outer cage is C180 with benzenoid rings, the strain is intermediate. 相似文献