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Stereological model tests and parameter estimators for the spatial Poisson–Voronoi tessellation are discussed. The tests aim to discriminate the Poisson–Voronoi tessellation from more regular or more irregular tessellations. The power of the model tests under some special parametric alternative hypotheses is investigated by simulation. Among the tests considered, the most powerful test is based on the variance of the section cell areas. Various stereological estimators for the model parameter of the spatial Poisson–Voronoi tessellation are compared with respect to their bias and variance by means of a Monte–Carlo study. Formulae are given for variance prediction. An estimator based on vertex counting is found to be the best. Robustness is investigated by applying the estimators to Voronoi tessellations generated by other point process models. 相似文献
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We develop a simple decision model which can be used for determining the optimum levels of order quantity, order cycle, and capacity change for a capacity-constrained, single-stage joint lot sizing/scheduling (JLS) situation. The model solution (i.e., capacity change) can also be converted into an equivalent setup time reduction. Thus, the model can be used to evaluate the effectiveness of capacity change and setup reduction alternatives. Therefore, the proposed model extends the capability for analysis over that of current JLS approaches. 相似文献
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This paper proposes a night-time vehicle detection method using variable Haar-like feature.The specific features of front vehicle cannot be obtained in road image at night-time because of light reflection and ambient light,and it is also difficult to define optimal brightness and color of rear lamp according to road conditions.In comparison,the difference of vehicle region and road surface is more robust for road illumination environment.Thus,we select the candidates of vehicles by analysing the difference,and verify the candidates using those brightness and complexity to detect vehicle correctly.The feature of brightness difference is detected using variable horizontal Haar-like mask according to vehicle size in the location of image.And the region occurring rapid change is selected as the candidate.The proposed method is evaluated by testing on the various real road conditions. 相似文献
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The flat laminar opposed jet diffusion flame was used to determine net rates of formation and destruction of nitric oxide under a wide range of temperatures and local fuel concentrations. In order to accomplish this the theoretical model of this flame was first validated with respect to experimental data on major species and temperature. Then the measured NO and temperature profiles were utilized in conjunction with the species conservation equation to obtain the desired result. 相似文献
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The reciprocal salt pair Sr2 SiO4 -Sr2 GeO4 -Ba2 GeO4 -Ba2 SiO4 was investigated using X-ray powder diffraction and DTA. Unlimited solubility in the low-K2 SO4 structure type (α') occurs throughout the system above 85°C. The nonlinear changes of some lattice constants of the solid solutions are discussed. A stable monoclinic low-temperature (β) form of Sr2 SiO4 was found which converts reversibly to the high-temperature α'-modification at 85°C. The enthalpy of the β-α' transition is 51 cal/mol. In the reciprocal salt pair the β-form solid solutions occur in a very narrow region below 85°C. 相似文献
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Polymorphism of Tricalcium Silicate and Its Solid Solutions 总被引:4,自引:0,他引:4
M. BIGARÉ A. GUINIER C. MAZIÈRES M. REGOURD N. YANNAQUIS W. EYSBL TH. HAHN E. WOERMANN 《Journal of the American Ceramic Society》1967,50(11):609-619
In tricalcium silicate and its solid solutions six modifications were established: one rhombohedral ( R ), two monoclinic ( M I , M II ), and three triclinic ( T I , T II , T III ). All these forms are rhombohedral or pseudorhombohedral and extremely similar; the variations in the X-ray diagrams and the transformation enthalpies are minute. Only three of the five transitions were observed by both X rays and DTA: T I - T II (600°), T III – M I (980°), and M I – M II (990°); one was established by DTA ( T II – T III , 920°) and one by X rays only ( M II – R , 1050°C). This scheme of polymorphism is compared critically with results of other authors, and the nature of the various displacive transformations is discussed. X-ray and DTA investigations of solid solutions of Ca3 SiO5 with Al2 O3 and ZnO established the phase relations as functions of temperature and composition. With Al2 O3 , two modifications ( T I and T II ) were stabilized; and with ZnO, five polymorphs ( T I T II , MI , M II , and R ). With both pure C3 S and the solid solutions, the results are consistent and have a close bearing on the constitution of alites in portland cement clinker. 相似文献