A ROBUST PLS PROCEDURE

A robust partial least squares(PLS)regression algorithm is developed.This is achieved by substitutionof the univariate regression steps in the iterative PLS2 algorithm by a robust alternative.The anglebetween loading vectors from both perturbed and unperturbed solutions is used as a measure ofrobustness.By means of a perturbation study on a structure-activity data set,it is demonstrated thatthe stability of the robust method is superior to standard PLS.     

昆明盘龙江江岸对震害的影响

如果在昆明及其附近地区发生强烈的破坏性地震,当地震波传播到盘龙江江岸这一特定的场地条件时,对震害会产生怎样的影响?本文根据在强震考察中看到的一些河岸破坏的情况和对盘龙江江岸地区的一些工程水文地质资料及局部地区脉动观测结果分析指出:(1)强震时江岸地区易发生地裂,地陷和塌方等地基失效现象而加大震害。(2)由于江岸地区的土层含有饱和的砂土层,强震时易引起砂土液化导致地基失效而加大震害。(3)由于江岸地形的影响,强震时对振动起放大作用而加大震害。所以在昆明的城市规划建设中,盘龙江两岸在离岸边30米内最好不要建筑任何结构物,以免在强震时造成严重的破坏。     

Studying ice sheet stability using the method of separation of variables

Abstract

Stability of two-dimensional stationary continental and marine ice sheets is studied using perturbations of ice sheet surface elevation and the margin position about a steady-state solution. Ice accumulation rate at the upper surface is specified as a function of elevation and span. Ice is considered as a Newtonian fluid. Linearisation and separation of variables yield a non-homogeneous eigenvalue problem. In case when the margin moves, a necessary condition for the existence of a solution is very restrictive on the functions of the bed profile and accumulation rate. The method of separation of variables is applicable when the margin is assumed to be stationary. Singularity of the perturbation at the margin is treated using the method of matched asymptotic expansions. Numerical experiments show that dependence of accumulation rate on elevation contributes strongly towards ice sheet instability. Bed slope, ice thickness at the grounding line of a marine ice sheet and equilibrium line inclination are the main parameters determining the ice sheet reaction to a surface perturbation.     

Effects of vertical wind shear on convective development during a landfall of severe tropical storm Bilis (2006)

Effects of vertical wind shear on convective development during the landfall of tropical storm Bilis (2006) are investigated with a pair of sensitivity experiments using a two-dimensional cloud-resolving model. The validated simulation data from Wang et al. [Wang, D., Li, X., Tao, W.-K., Liu, Y., Zhou, H., 2009: Torrential rainfall processes associated with a landfall of severe tropical storm Bilis (2006): A two-dimensional cloud-resolving modeling study. Atmos. Res., 91, 94–104.] are used as the control experiment. The difference between the control and sensitivity experiments is that vertically varying zonal winds in the control experiment are replaced by their mass-weighted means in the sensitivity experiment. The imposed vertical velocity with ascending motion in the upper troposphere and descending motion in the lower troposphere is responsible for dominant stratiform rainfall on 15 July. The vertical wind shear does not have important impacts on development of stratiform rainfall. One day later, imposed upward motion extends to the lower troposphere. The inclusion of negative vertical wind shear produces well-organized convection and strong convective rainfall because it causes kinetic energy transfer from large-scale forcing to perturbation circulations.     

热带气旋的内、外区结构──Ⅰ.正压模式

将热带气旋分为内外两区，两区的空间、时间及物理量有不同的尺度，应用尺度分析和摄动法到热带气旋的两个区域，分别在正压模式和斜压模式中求得了这两个区域的控制方程，在两个模式中，还解析地求得了两个区域的流场和气压场，得到的结果与实际热带气旋的结构较为接近。研究表明，热带气旋内区和外区有不同的控制方程，内区受旋转风和一个演化方程制约，而外区受梯度风和另一个演化方程制约。     

Statistical evaluation of compositional changes in volcanic gas chemistry: a case study

The geochemical analysis of fumarolic gases collected at quiescent and active volcanic systems over time is one of the main tools to understand changes in the state of activity for surveillance and risk assessment. The continuous output of chemical species through fumarolic activity, which characterizes the inter-eruptive intervals, has also a major and general influence on the environment. The mobilization of chemical species due to weathering of volcanic rocks, or the input of gaseous components from fumarolic activity, results in some kind of modification of the environment affecting, in particular, water, soils, and the consequent growth of the plants present in these areas. In this paper, an investigation on the chemical composition of fumarolic gases collected at Vulcano island (Sicily, southern Italy) is performed, with the aim to discover how data changes during the monitored period of time, and to design a strategy for the environmental surveillance of volcanic systems taking into account the nature of the analyzed data. In order to summarize the contribution of all the components that can affect the chemical composition of volcanic gases, a multivariate statistical approach appears to be suitable. Since many of those methods assume independent observations, the possible presence of time-dependent structures should be carefully verified. In this framework, given the compositional nature of geochemical data, we have applied recent theoretical and practical developments in the field of compositional data analysis to work in the correct sample space and to isolate groups of parts responsible for significant changes in the gas chemistry. The proposed approach can be generalized to the investigation of complex environmental systems.     

PUVM2测轨方法的误差估计及其传播

本文根据误差理论,对ＰＵＶＭ２测轨方法的误差及其传播规律进行了初步的分析和研究,给出了卫星的轨道根数σ和空间位置ｒ↑→的内符合误差估计公式。     

Inversion of dynamic production data for permeability: fast streamline-based computation of sensitivity coefficients of fractional flow rate

Generation of permeability field in a reservoir model that matchs historical dynamic production data requires an inverse calculation. A gradient method is typically used to solve the inverse minimization problem and requires sensitivity coefficients of reservoir responses, e.g. fractional flow rate or pressure, with respect to the change in the permeability. This paper presents a novel semi-analytical streamline-based method for computing such sensitivity coefficients under the framework of two-phase (oil-water) flow conditions. This method is shown to be significantly faster and generate permeability fields with lower objective function than the traditional perturbation method. The method decomposes the multiple-dimensional full flow problem into multiple 1D problems along streamlines. The sensitivity of fractional flow rate at the production well is directly related to the sensitivity of time-of-flight (TOF) along each individual streamline and the sensitivity of pressure at grid cells along the streamline. The sensitivity of TOF of a streamline can be obtained analytically. The sensitivity of pressure is obtained as part of a fast single phase flow simulation. The proposed method is implemented in a geostatistically based inverse technique, called the sequential self-calibration (SSC) method. Results for fractional flow rate sensitivities are presented and compared with the traditional perturbation method. This new method can be easily extended to compute sensitivity coefficients of saturation (concentration) data.     

Assessing mammal responses to perturbations in temperate aridlands of Argentina

Loss of species richness and reduced abundance have been the main responses to perturbations of small- and medium-sized mammals in arid and semi-arid areas. Nonetheless, some mammal species whose habitat requirements are met in disturbed patches may benefit from structural changes in the environment brought about by perturbations.In desert areas of Argentina different mammal responses are attributable to both a lower complexity of disturbed patches and a decrease in sheltered places. Therefore, species associated with high plant cover either decrease in number or become locally extinct at sites affected by fire or grazing, whereas species using open areas are favored by these events.The negative effects historically assigned to different disturbances may be mitigated by adopting a hierarchical approach that considers patch diversity in different successional stages as well as the multiple opportunities of patch occupation by mammal species.     

APPROXIMATE SOLUTION USING A PERTURBATION METHOD FOR DETENTION POND DESIGN

1 INTRODUCTION Mountains higher than 100m occupy 63% of the land area in Taiwan. Serious flood disasters and muddy flows usually occur in the rainy season. To reduce the disasters from hillslope development, the government published the Norm of Soil and Water Conservation Treatment (NSWCT) in 1994. One of the most important treatments is that detention ponds and grit chambers are essential facilities for reducing increased peak flow disasters and sediment yield. 309 volumes on soil…