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991.
Motivated by the problem of labeling maps, we investigate the problem of computing a large non-intersecting subset in a set of n rectangles in the plane. Our results are as follows. In O(n log n) time, we can find an O(log n)-factor approximation of the maximum subset in a set of n arbitrary axis-parallel rectangles in the plane. If all rectangles have unit height, we can find a 2-approximation in O(n log n) time. Extending this result, we obtain a (1 + 1/k)-approximation in time O(n log n + n2k−1) time, for any integer k ≥ 1. 相似文献
992.
This paper deals with some studies pertaining te, nonprocessive recombinase viz. Topoisomerases III, IV. The mathematics of tangles is found to be very useful in studying topoisomerases and recombinases (processive and nonprocessive). It has been seen that the enzyme acts on the DNA if it is in a certain configuration. Electron micrographs of the enzyme-DNA complex show the enzyme as a blob with DNA looping out of it, but they are unable to determine the configuration of the DNA within the blob. By using knot theory and tangle calculus, the configuration of DNA within the enzyme blob as well as the enzyme action has been determined in saine cases. 相似文献
993.
V. Ramachandhran S. K. Samanta B. M. Misra 《Journal of Radioanalytical and Nuclear Chemistry》1998,235(1-2):121-124
The Comprehensive Test Ban Treaty calls for the monitoring of aerosol radionuclides throughout the globe. Pacific Northwest
National Laboratory has developed the Radionuclide Aerosol Sampler/Analyzer (RASA) for the Department of Energy to automatically
collect and measure radioactive aerosols from the atmosphere. The RASA passes high volumes of air through a 3MTM Substrate Blown Microfiber Media (SBMF) specifically designated as SBMF-40VF. It then automatically moves the filter media
in front of a high-purity germanium detector and collects a gamma spectrum. If further analysis on the filter is desired,
the filter is sent to a laboratory and radiochemical analysis is performed. This paper discusses the method of dissolution
of the SBMF-40VF filter media and the separation of the radioisotopes of interest. 相似文献
994.
C. Janardanan P. V. Achuthan A. Ramanujan B. M. Misra 《Journal of Radioanalytical and Nuclear Chemistry》1997,222(1-2):15-20
Four nuclear methods are critically regarded from the point of view of the nondestructive analyses of the ancient coins. The information they can give and the reliability of each method are discussed. The coins analyzed are eleven Thasian tetradrachmas from the Chiselet hoard, minted during the second and first centuries BC. Much information can be obtained about the original ore and ancient minting technology. 相似文献
995.
996.
Sanjeet Singh Pankaj Gupta Davinder Bhatia 《Applied mathematics and computation》2005,170(2):536-1260
In this paper, we study multiparametric sensitivity analysis for programming problems with linear-plus-linear fractional objective function using the concept of maximum volume in the tolerance region. We construct critical regions for simultaneous and independent perturbations of one row or one column of the constraint matrix in the given problem. Necessary and sufficient conditions are given to classify perturbation parameters as ‘focal’ and ‘nonfocal’. Nonfocal parameters can have unlimited variations, because of their low sensitivity in practice, these parameters can be deleted from the analysis. For focal parameters, a maximum volume tolerance region is characterized. Theoretical results are illustrated with the help of a numerical example. 相似文献
997.
A. S. Gupta J. C. Misra M. Reza 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2005,56(6):1030-1047
An analysis is made of the steady shear flow of an incompressible viscous electrically conducting fluid past an electrically
insulating porous flat plate in the presence of an applied uniform transverse magnetic field. It is shown that steady shear
flow exists for suction at the plate only when the square of the suction parameter S is less than the magnetic parameter Q. In this case the velocity at a given point increases with increase in either the magnetic field or suction velocity. The
shear stress at the plate increases with increase in either S or the free-stream shear-rate parameter σ1 or Q. The analysis further reveals that solution exists for steady shear flow past a porous flat plate subject to blowing only
when the square of the blowing parameter S1 is less than Q. It is found that the induced magnetic field at a given location decreases with increase in Q. Further the wall shear stress decreases with increase in S1. No steady shear flow is possible for blowing at the plate when S12 > Q.
Received: June 16, 2004; revised: October 24, 2004 相似文献
998.
Pankaj K. Agarwal Herbert Edelsbrunner Yusu Wang 《Discrete and Computational Geometry》2004,32(1):37-53
The writhing number measures the global geometry of
a closed space curve or knot.
We show that this measure is related to the average winding number
of its Gauss map.
Using this relationship, we give an algorithm for computing
the writhing number for a polygonal knot with n edges
in time roughly proportional to n1.6.
We also implement a different, simple algorithm and provide
experimental evidence for its practical efficiency. 相似文献
999.
Prakash Mathews Rahul Basu D. Indumathi E. Laenen Swapan Majhi Anuradha Misra Asmita Mukherjee W. Vogelsang 《Pramana》2004,63(6):1367-1379
This is the report of the QCD working sub-group at WHEPP-8 which was part of the QCD and QGP working group. Discussion and
work on some aspects of resummation and parton distribution are reported. 相似文献
1000.
Sharma SK Misra AK Lucey PG Wiens RC Clegg SM 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,68(4):1036-1045
Combined remote laser-induced breakdown spectroscopy (LIBS) and Raman spectroscopy investigations at a distance of 8.6m have been carried out in air and under a simulated Martian atmosphere of 933Pa (7Torr) CO(2) on calcite (CaCO(3)), gypsum (CaSO(4).2H(2)O), and elemental sulfur (S), and LIBS investigations on chalcopyrite (CuFeS(2)) and pyrite (FeS(2)). Both Raman and LIBS techniques have also been used sequentially in air on hematite-coated calcite crystals and on a sample of anhydrite covered with basaltic dust. These experiments demonstrate that by using a frequency-doubled Nd:YAG pulsed laser co-radiating 1064 nm and 532 nm laser beams with a 5x beam expander, it is possible to measure simultaneously both the Raman and LIBS spectra of calcite, gypsum and elemental sulfur by adjusting the laser power electronically. The spectra of calcite, gypsum, and elemental sulfur contain fingerprint Raman lines; however, it was not possible to measure the remote Raman spectra of pyrite and chalcopyrite because of low intensities of Raman lines. In the cases of CuFeS(2), FeS(2), and elemental sulfur, S atomic emission lines in the LIBS spectra were detected only in 7Torr of CO(2) pressure and not in air. No S atomic emission lines were detected for gypsum in air or in CO(2). In the case of coated/dusted minerals, it was possible to remove the coating or dust with the focused LIBS laser and measure the Raman spectra of subsurface minerals with a 532 nm laser excitation. The complementary nature of these two techniques is highlighted and discussed. 相似文献