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1.
Chiang E. I. Lovering J. R. Millis R. L. Buie M. W. Wasserman L. H. Meech K. J. 《Earth, Moon, and Planets》2003,92(1-4):49-62
We review ongoing efforts to identify occupants of mean-motion resonances(MMRs) and collisional families in the Edgeworth–Kuiper belt. Directintegrations of trajectories of Kuiper belt objects (KBOs) reveal the 1:1(Trojan), 5:4, 4:3, 3:2 (Plutino), 5:3, 7:4, 9:5, 2:1 (Twotino), and 5:2 MMRsto be inhabited. Apart from the Trojan, resonant KBOs typically have largeorbital eccentricities and inclinations. The observed pattern of resonanceoccupation is consistent with resonant capture and adiabatic excitation bya migratory Neptune; however, the dynamically cold initial conditions priorto resonance sweeping that are typically assumed by migration simulationsare probably inadequate. Given the dynamically hot residents of the 5:2 MMRand the substantial inclinations observed in all exterior MMRs, a fraction ofthe primordial belt was likely dynamically pre-heated prior to resonancesweeping. A pre-heated population may have arisen as Neptune gravitationallyscattered objects into trans-Neptunian space. The spatial distribution of Twotinosoffers a unique diagnostic of Neptune's migration history. The Neptunian Trojanpopulation may rival the Jovian Trojan population, and the former's existence isargued to rule out violent orbital histories for Neptune. Finally, lowest-order seculartheory is applied to several hundred non-resonant KBOs with well-measured orbitsto update proposals of collisional families. No convincing family is detected. 相似文献
2.
The ordinary kriging method, a geostatistical interpolation technique, was applied for developing contour maps of design storm depth in northern Taiwan using intensity–duration–frequency (IDF) data. Results of variogram modelling on design storm depths indicate that the design storms can be categorized into two distinct storm types: (i) storms of short duration and high spatial variation and (ii) storms of long duration and less spatial variation. For storms of the first category, the influence range of rainfall depth decreases when the recurrence interval increases, owing to the increasing degree of their spatial independence. However, for storms of the second category, the influence range of rainfall depth does not change significantly and has an average of approximately 72 km. For very extreme events, such as events of short duration and long recurrence interval, we do not recommend usage of the established design storm contours, because most of the interstation distances exceed the influence ranges. Our study concludes that the influence range of the design storm depth is dependent on the design duration and recurrence interval and is a key factor in developing design storm contours. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
3.
We limit the photometric contrast of solar giant convection cells using 525.6 nm continuum images obtained on 15 days in May 1985. The r.m.s. of the giant cell intensity pattern must be less than or equal to the observed r.m.s. on spatial scales 80 to 240 Mm which is 0.023% or, equivalently, 0.33 K. However, the spatial scale and time-scale dependence of the variance demonstrate that giant cells are not the source of the observed variance. Consequently, a tighter constraint on the r.m.s. of the giant cell pattern may be placed, namely 0.016% or 0.23 K. This limit is consistent with temperature perturbations estimated from recent nonlinear simulations of global-scale solar convection. We use this limit on the r.m.s. of the giant cell pattern to estimate that the contribution of giant cells to the fluctuation of the solar irradiance on a one-month time-scale is less than 3 × 10–5 S. 相似文献
4.
The performance of Salter's cam as an energy extractor from ocean waves is studied numerically on the basis of linear theory of surface waves and floating bodies. Quantities of engineering interest such as efficiency, induced motion and reaction forces are presented and discussed both for fixed and for partly constrained cam shafts. 相似文献
5.
Morphotectonics and incision of the Kaoping submarine canyon, SW Taiwan orogenic wedge 总被引:1,自引:0,他引:1
The Kaoping submarine canyon developed on the frontal orogenic wedge off SW Taiwan and is the largest one among others. The canyon begins at the mouth of the Kaoping River, crosses the narrow shelf and broad slope region, and finally merges into the northern Manila Trench for a distance of about 260 km. Using reflection seismic sections and bathymetric mapping this paper reveals the geomorphic characteristics of the Kaoping Canyon strongly related to structural and sedimentary processes. The combined morphometry statistics analysis, seismic interpretations of structures and examinations of detailed bathymetric charts indicate that regional canyon morphology is strongly linked to intrusions of mud diapirs in the upper reach of the canyon and thrust faulting in the middle and lower reaches which produce two prominent morphological breaks of the course of the Kaoping Canyon with two sharp bends. Although excavation of floor and enlargement of the Kaoping Canyon are mainly attributed to downslope erosion of seabed, incision of this canyon is also strongly complicated by mud diapiric intrusions (upper reach), westward thrust faults (middle reach), and regional base level tilting (lower reach). The resultant cross-sectional morphology along the Kaoping Canyon changes considerably, ranging from U-shaped, broad V-shaped, to irregular troughs. The Kaoping Canyon may be served as a variant of canyon model of active margins with a distinct morphology of two sharp bends along the canyon course associated with structure deformation. 相似文献
6.
Scattering of SH waves in a half-space with simple overground structures is studied analytically. For two-dimensional structures, such as shells, shear walls and a slab-bridge over a river, the method of matched asymptotics is used for sinusoidal waves long compared to the thickness of the structures. Resonance features are deduced analytically and calculated numerically for various incidences and other parameters. 相似文献
7.
Random variable simulation has been applied to many applications in hydrological modelling, flood risk analysis, environmental impact assessment, etc. However, computer codes for simulation of distributions commonly used in hydrological frequency analysis are not available in most software libraries. This paper presents a frequency‐factor‐based method for random number generation of five distributions (normal, log–normal, extreme‐value type I, Pearson type III and log‐Pearson type III) commonly used in hydrological frequency analysis. The proposed method is shown to produce random numbers of desired distributions through three means of validation: (1) graphical comparison of cumulative distribution functions (CDFs) and empirical CDFs derived from generated data; (2) properties of estimated parameters; (3) type I error of goodness‐of‐fit test. An advantage of the method is that it does not require CDF inversion, and frequency factors of the five commonly used distributions involves only the standard normal deviate. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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In this paper, characterization of cirrus clouds are made by using data from ground based polarization lidar and radiosonde measurements over Chung-Li (24.58°N, 121.10°E), Taiwan for a period of 1999–2006. During this period, the occurrence of cirrus clouds is about 37% of the total measurement nights over the lidar site. Analysis of the measurement gives the statistical characteristics about the macrophysical properties such as occurrence height, ambient temperature, and its geometrical thickness while the microphysical properties are interpreted in terms of extinction coefficient, optical depth, effective lidar ratio and depolarization ratio. The effective lidar ratio has been retrieved by using the simulation technique of backscattered lidar signals. The effect of multiple scattering has been taken into the account by a model calculation. Summer (Jun–Aug) shows the maximum appearances of cirrus due to its formation mechanism. It is shown that tropopause cirrus clouds may occur with a probability of about 24%. These clouds are usually optically thin and having laminar in structure with some cases resembling the characteristics similar to that of polar stratospheric clouds (PSCs). The radiative properties of the cirrus clouds are also discussed in detail by the empirical equations with results show a positive feedback on any climate change. 相似文献