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41.
Bago River is an important river in Myanmar. Although shorter than other rivers, it has its own river system, and people along
the river rely heavily on it for their daily lives. The upper part of the watershed has changed rapidly from closed forest
to open forest land in the 1990s. Since the recent degradation of the forest environment, annual flooding has become worse
during the rainy season in Bago City. This paper aims at determining soil conservation prioritization of watershed based on
soil loss due to erosion and morphometric analysis in the Bago Watershed by integrating remote sensing and geographic information
system (GIS) techniques. In this study, soil erosion of the Bago watershed was determined using the Universal Soil Loss Equation.
Such factormaps as rainfall, soil erodibility, slope length gradient, and crop management were compiled as input parameters
for the modeling; and the soil loss from 26 sub-watersheds were estimated. Then, the soil erosion maps of the Bago watershed
for 2005 were developed. The resulting Soil Loss Tolerance Map could be utilized in developing watershed management planning,
forestry management planning, etc. 相似文献
42.
When standard boundary element methods (BEM) are used in order to solve the linearized vector Molodensky problem we are confronted with
two problems: (1) the absence of O(|x|−2) terms in the decay condition is not taken into account, since the single-layer ansatz, which is commonly used as representation
of the disturbing potential, is of the order O(|x|−1) as x→∞. This implies that the standard theory of Galerkin BEM is not applicable since the injectivity of the integral operator
fails; (2) the N×N stiffness matrix is dense, with N typically of the order 105. Without fast algorithms, which provide suitable approximations to the stiffness matrix by a sparse one with O(N(logN)
s
), s≥0, non-zero elements, high-resolution global gravity field recovery is not feasible. Solutions to both problems are proposed.
(1) A proper variational formulation taking the decay condition into account is based on some closed subspace of co-dimension
3 of the space of square integrable functions on the boundary surface. Instead of imposing the constraints directly on the
boundary element trial space, they are incorporated into a variational formulation by penalization with a Lagrange multiplier.
The conforming discretization yields an augmented linear system of equations of dimension N+3×N+3. The penalty term guarantees the well-posedness of the problem, and gives precise information about the incompatibility
of the data. (2) Since the upper left submatrix of dimension N×N of the augmented system is the stiffness matrix of the standard BEM, the approach allows all techniques to be used to generate
sparse approximations to the stiffness matrix, such as wavelets, fast multipole methods, panel clustering etc., without any
modification. A combination of panel clustering and fast multipole method is used in order to solve the augmented linear system
of equations in O(N) operations. The method is based on an approximation of the kernel function of the integral operator by a degenerate kernel
in the far field, which is provided by a multipole expansion of the kernel function. Numerical experiments show that the fast
algorithm is superior to the standard BEM algorithm in terms of CPU time by about three orders of magnitude for N=65 538 unknowns. Similar holds for the storage requirements. About 30 iterations are necessary in order to solve the linear
system of equations using the generalized minimum residual method (GMRES). The number of iterations is almost independent
of the number of unknowns, which indicates good conditioning of the system matrix.
Received: 16 October 1999 / Accepted: 28 February 2001 相似文献
43.
An equation of state (EOS) explicit in Helmholtz free energy has been improved to calculate the PVTx and vapor–liquid phase equilibrium properties of CH4–CO2 fluid mixture. This EOS, where four mixing parameters are used, is based on highly accurate EOSs recommended by NIST for pure components (CH4 and CO2) and contains a simple generalized departure function presented by Lemmon and Jacobsen (1999). Comparison with experimental data available indicates that the EOS can calculate both vapor–liquid phase equilibrium and volumetric properties of this binary fluid system with accuracy close to that of experimental data up to high temperature and pressure within full range of composition. The EOS of CH4–CO2 fluid, together with the updated Gibbs free energy model of solid CO2 (dry ice), is applied to calculate the CH4 content (xCH4) and molar volume (Vm) of the CH4–CO2 fluid inclusion based on the assumption that the volume of an inclusion keeps constant during heating and cooling. diagrams are presented, which describe phase transitions involving vapor, liquid and CO2 solid phases of CH4–CO2 fluid inclusions. Isochores of CH4–CO2 inclusions at given and Vm can be easily calculated from the improved EOS. 相似文献
44.
45.
Ruzhong Li 《中国地理科学(英文版)》2008,18(4):348-355
Many kinds of uncertainties are involved, such as random, fuzzy, grey, unascertained property and so on, in soil erosion process. To exactly predict the non-point source pollution loads, some uncertainties should be taken into consideration. Aiming at the deficiency of present blind number theory being helpless for fuzziness, a novel blind number, i.e. extended-blind number, was introduced by substituting a set of triangular fuzzy numbers (TFNs), expressed as a-cuts, for interval values in present blind number, and the expected value of extended-blind number was also brought forward by referring to the current blind number theory. On the basis of denoting the parameters of Uni- versal Soil Loss Equation (USLE) as extended-blind parameters, a novel USLE model was established for quantitatively evaluating soil erosion loss and non-point source pollution loads. As a case, the uncertain USLE was employed for predicting the soil erosion loss and non-point source pollution loads of absorbed nitrogen and phosphorus in a dis- trict in the Hangbu-Fengle River basin, in the upstream of Chaohu Lake watershed. The results show that it is feasible in theory to extend blind number into fuzzy environment and reliable on conclusion to apply extended-blind number theory for predicting non-point source pollution loads. 相似文献
46.
针对使用NCEP再分析数据和辐射传输方程法反演SST出现偏差较大的问题,以HJ-1B SST反演为例,从修正大气透过率入手,提出中心点算法和均值点算法2种辐射传输方程改进算法。2种改进算法对大气透过率偏差和HJ SST反演偏差均有明显改善,反演的HJ SST与MODIS SST均呈现显著的一致性。MODIS SST验证表明2种改进算法的平均偏差和均方差在0.5 ℃左右;浮标SST验证表明均值点算法的反演精度较高,其平均偏差为0.55 ℃,而中心点算法的为0.81 ℃。 相似文献
47.
48.
James M. Lattimer 《Astrophysics and Space Science》2007,308(1-4):371-379
Recent measurements of thermal radiation from neutron stars have suggested a rather broad range of radiation radii (
). Sources in M13 and Omega Cen imply R
∞∼12–14 km, but X7 in 47 Tuc implies R
∞∼16–20 km and RX J1856-3754 R
∞>17 km. If these measurements are all correct, only a limited selection of EOS’s could be consistent with them, but a broad
range of neutron star masses (up to 2 M⊙) would also be necessary. The surviving equations of state are incompatible with significant softening above nuclear saturation
densities, such as would occur with Boson condensates, a low-density quark-hadron transition, or hyperons. Other potential
constraints, such as from QPO’s, radio pulsar mass and moment of inertia measurements, and neutron star cooling, are compared.
US DOE Grant DE-FG02-87ER-40317. 相似文献
49.
Temperature and Water Vapor Weighting Functions from Radiative Transfer Equation with Surface Emissivity and Solar Reflectivity 总被引:8,自引:2,他引:8
Linearization of Radiative Transfer Equation (RTE) is the key step in physical retrieval of atmospheric temperature and moisture profiles from InfRared (IR) sounder observations. In this paper, the successive forms of temperature and water vapor mixing ratio component weighting functions are derived by applying one term variation method to RTE with surface emissivity and solar reflectivity contained. Retrivals of temperature and water vapor mixing ratio profiles from simulated Atmospheric Infrared Sounder (AIRS) observations with surface emissivity and solar reflectivity are presented. 相似文献
50.
N.?HiraoEmail author E.?Ohtani T.?Kondo T.?Kikegawa 《Physics and Chemistry of Minerals》2004,31(6):329-336
The stability and pressure–volume equation of state of iron–silicon alloys, Fe-8.7 wt% Si and Fe-17.8 wt% Si, have been investigated using diamond-anvil cell techniques up to 196 and 124 GPa, respectively. Angular–dispersive X-ray diffractions of iron–silicon alloys were measured at room temperature using monochromatic synchrotron radiation and an imaging plate (IP). A bcc–Fe-8.7 wt% Si transformed to hcp structure at around 1636 GPa. The high-pressure phase of Fe-8.7 wt% Si with hexagonal close-packed (hcp) structure was found to be stable up to 196 GPa and no phase transition of bcc–Fe-17.8 wt% Si was observed up to 124 GPa. The pressure–volume data were fitted to a third-order Birch–Murnaghan equation of state (BM EOS) with zero–pressure parameters: V0=22.2(8) Å3, K0=198(9) GPa, and K0=4.7(3) for hcp–Fe-8.7 wt% Si and V0=179.41(45) Å3, K0=207(15) GPa and K0=5.1(6) for Fe-17.8 wt% Si. The density and bulk sound velocity of hcp–Fe-8.7 wt% Si indicate that the inner core could contain 3–5 wt% Si. 相似文献