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981.
The paper presents the analytical geometric details of the mathematical modeling of a single point cutting tool with a generic profile. The grinding angles and the ground depths on the tool are allowed to vary along the tool flanks and face, altering the cutting angles from point to point. The surface modeling begins with the creation of a tool blank model. Then unbounded surfaces are considered and transformed to get the cutting tool surfaces. The intersection of these surfaces gives the complete model of the tool. Starting from the basic model where the tool face and flank are planar, the generalization of the geometric design has been done in two steps to give free-form shapes to the tool surfaces, termed as the two generations of the generic profile. Then a forward and inverse mapping has been presented for the basic model and the two generations of the generic tool to relate the grinding angles with the prevalent nomenclatures (ASA, ORS and NRS). The model has been validated and the variation of tool angles with the grinding parameters has been illustrated with an example. 相似文献
982.
983.
Hande Yaman 《European Journal of Operational Research》2011,211(3):442-451
In this paper, we study allocation strategies and their effects on total routing costs in hub networks. Given a set of nodes with pairwise traffic demands, the p-hub median problem is the problem of choosing p nodes as hub locations and routing traffic through these hubs at minimum cost. This problem has two versions; in single allocation problems, each node can send and receive traffic through a single hub, whereas in multiple allocation problems, there is no such restriction and a node may send and receive its traffic through all p hubs. This results in high fixed costs and complicated networks. In this study, we introduce the r-allocation p-hub median problem, where each node can be connected to at most r hubs. This new problem generalizes the two versions of the p-hub median problem. We derive mixed-integer programming formulations for this problem and perform a computational study using well-known datasets. For these datasets, we conclude that single allocation solutions are considerably more expensive than multiple allocation solutions, but significant savings can be achieved by allowing nodes to be allocated to two or three hubs rather than one. We also present models for variations of this problem with service quality considerations, flow thresholds, and non-stop service. 相似文献
984.
985.
Liqiang FengTianshu Chu 《Physics letters. A》2011,375(41):3641-3648
In the present Letter, we theoretically discuss the optimum conditions for generating ultrashort attosecond pulse in three-color field with a model He exposed to the intense 5 fs, 800 nm fundamental field and the two weak control fields of 25 fs, 400 nm and 25 fs, 1600 nm. Through investigating the controlling factors in HHG spectra generation via manipulating the laser parameters of the three fields, we demonstrate that properly increasing the pulse intensity of 800 nm and 1600 nm fields at the same time with zero phase effects is an effective way to generate short attosecond pulses. Finally, an isolated pulse of 7 as is predicted by Fourier transforming an ultrabroad XUV continuum of 393 eV with phase compensation. 相似文献
986.
Mohammad A. Alim A.K. BatraSudip Bhattacharjee M.D. Aggarwal 《Physica B: Condensed Matter》2011,406(5):1088-1095
The lithium niobate (LiNbO3 or LN) single crystal is grown in-house. The ac small-signal electrical characterization is conducted over a temperature range 35≤T≤150 °C as a function of measurement frequency (10≤f≤106 Hz). Meaningful observation is noted only in a narrow temperature range 59≤T≤73 °C. These electrical data when analyzed via complex plane formalisms revealed single semicircular relaxation both in the complex capacitance (C?) and in the modulus (M?) planes. The physical meaning of this kind of observation is obtained on identifying the relaxation type, and then incorporating respective equivalent circuit model. The simplistic non-blocking nature of the equivalent circuit model obtained via M?-plane is established as the lumped relaxation is identified in the C?-plane. The feature of the eventual equivalent circuit model allows non-blocking aspect for the LN crystal attributing to the presence of the operative dc conduction process. Identification of this leakage dc conduction via C?-plane is portrayed in the M?-plane where the blocking nature is removed. The interacting interpretation between these two complex planes is successfully presented. 相似文献
987.
988.
989.
ZHAO Ying-hao MA Tong-hui ZHENG Yong-chen ZHANG Kun YANG Jing-bo YANG Long-fei YANG Zhi-guang SHAO Guo-guang 《高等学校化学研究》2011,27(1):80-82
Matrix metalloproteinase-9(MMP-9) and p53 genes play an essential role in the multi-step process of tumorigenesis in lung cancer. Single nucleotide polymorphisms(SNPs) of MMP-9 and p53 genes are associated with the risk and progression of many cancers. In this study, we evaluated the association of the R279Q polymorphism of MMP-9 or the A1/A2 polymorphism of p53 gene with the risk of no-small-cell lung cancer(NSCLC) in Han population of Northeast China. We examined the frequency of SNPs in the two kinds of ... 相似文献
990.
Jude Lakbub Antibe Pouliwe Alexander Kamasah Cheng Yang Peng Sun 《Electroanalysis》2011,23(10):2270-2274
In this paper, the electrochemical behaviors of a single gold nanoparticle attached on a nanometer sized electrode have been studied. The single nanoparticle was characterized by using electrochemical methods. Since there is only one nanoparticle on the electrode, unarguable information for that sized particle could be obtained. Our preliminary results show that it becomes more difficult to oxidize gold nanoparticle or reduce gold nanoparticle oxide as the radius of the particle becomes smaller. Also, the peak potential of the reduction of gold nanoparticle oxide is proportional to the reciprocal of the radius of the particle. 相似文献