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| 2. |
- Bose, Prosenjit, et al.
(author)
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Online routing in convex subdivisions
- 2000
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In: Algorithms and Computation. - Berlin : Encyclopedia of Global Archaeology/Springer Verlag. - 3540412557 ; , s. 47-59
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Conference paper (peer-reviewed)abstract
- We consider online routing algorithms for finding paths between the vertices of plane graphs. We show (1) there exists a routing algorithm for arbitrary triangulations that has no memory and uses no randomization, (2) no equivalent result is possible for convex subdivisions, (3) there is no competitive online routing algorithm under the Euclidean distance metric in arbitrary triangulations, and (4) there is no competitive online routing algorithm under the link distance metric even when the input graph is restricted to be a Delaunay, greedy, or minimum-weight triangulation.
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| 3. |
- Bose, Prosenjit, et al.
(author)
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Online routing in convex subdivisions
- 2002
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In: International journal of computational geometry and applications. - 0218-1959. ; 12:4, s. 283-295
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Journal article (peer-reviewed)abstract
- We consider online routing algorithms for finding paths between the vertices of plane graphs. We show (1) there exists a routing algorithm for arbitrary triangulations that has no memory and uses no randomization, (2) no equivalent result is possible for convex subdivisions, (3) there is no competitive online routing algorithm under the Euclidean distance metric in arbitrary triangulations, and (4) there is no competitive online routing algorithm under the link distance metric even when the input graph is restricted to be a Delaunay, greedy, or minimum-weight triangulation.
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| 4. |
- Gutierrez, P, et al.
(author)
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An investigation of errors in estimates of the cometary nuclei active area fractions
- 2003
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 401:2, s. 755-761
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Journal article (peer-reviewed)abstract
- Active area fractions of cometary nuclei are often estimated by comparing the observed water production rates with theoretical rates obtained by applying the fast rotator or subsolar point approximations to spherical model nuclei. Any discrepancy between observed and theoretical production rates is interpreted as a certain degree of dust mantling (or in some cases hyper activity) of the object. We here investigate the typical errors introduced in such active area fraction estimates by the usage of oversimplified spherical model nuclei. This is done by first calculating the production rates of slowly rotating irregular model bodies with different activity patterns on their surfaces and arbitrary spin axis orientations, for which solar illumination is treated properly. Next, the production rates of the spherical model objects under averaged insolation are compared to the production rates of the complex model objects in an attempt to recover the known active area fraction of the latter bodies. We then find that the fast rotator and subsolar point approximations generally yield large over- and underestimates of the active area fraction, depending on the characteristics of the simulated complex nuclei. Acceptable relative errors ( <100%) only occur at small heliocentric distances, and the subsolar point approximation yields somewhat better results than the fast rotator approximation.
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| 6. |
- Xu, Huailiang, et al.
(author)
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Radiative lifetime and transition probabilities in CdI and CdII
- 2004
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In: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 70:4
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Journal article (peer-reviewed)abstract
- Radiative lifetimes of 11 levels belonging to the 5s5p P-1(1)o 5snd D-3(1,2) (n=6-9) and 5sns S-3(1) (n=7,8) series of Cd I, and of 5 levels of Cd II (i.e., 4d(10)5p P-2(1/2.3/2)o, 4d(10)6s S-2(1/2), and 4d(10)5d D-2(3/2,5/2)) have been measured using the time-resolved laser-induced fluorescence technique. Free neutral and singly ionized cadmium atoms have been generated by laser ablation. Single- or two-step excitation processes were considered to populate the levels under study. Branching fractions of Cd II transitions have been measured by laser-induced breakdown spectroscopy. Transition probabilities and oscillator strengths for Cd I and Cd II spectral lines originating from the above states as well as from the 4d(9)5 s(22)D(3/2,5/2) states of Cd II have been deduced by combining the experimental lifetimes and theoretical branching fractions obtained in multiconfigurational relativistic Hartree-Fock calculations taking core-polarization effects into account.
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