Composition and classification of clasts in the St. Mesmin LL chondrite breccia

Seven samples of the unique St. Mesmin meteorite have been analyzed by instrumental and radiochemical neutron activation analysis for Na, Ca, Sc, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, Se, In, Sm, Yb, Ir and Au. St. Mesmin is unique in being the only ordinary chondrite known to contain an unmelted xenolith of another ordinary chondrite. Data for two host matrix samples and three light clasts are consistent with their classification as LL chondrite material. The composition of the large dark xenolith confirms earlier evidence that it is an H chondrite; volatile abundances are consistent with it being highly shocked, petrologic type-4 material. In an olivine microporphyry, siderophile abundances are mostly about 0.13 times LL abundances, an apparent indication of metal loss during the shock melting which produced the clast. As in other regolithic chondrites, the dark host has higher contents of highly volatile elements than do the light clasts. We suggest that this results from a combination of differences in intensity of preexisting metamorphism as well as a redistribution of volatiles during regolith gardening.The H-group xenolith in St. Mesmin is a relatively recent addition to the parent body (< 1.4 Ga ago), but it is argued that this does not require regolith activity at that time. Rather the view is supported that the regolith period occurred very early in the meteorite's history (&gsim;4.0 Ga ago) and may have been related to the growth of the parent body. The H-group fragment may be part of the projectile whose impact excavated the St. Mesmin meteoroid from the LL parent body.     

Application of wavelet‐based multi‐model Kalman filters to real‐time flood forecasting

This paper presents the application of a multimodel method using a wavelet‐based Kalman filter (WKF) bank to simultaneously estimate decomposed state variables and unknown parameters for real‐time flood forecasting. Applying the Haar wavelet transform alters the state vector and input vector of the state space. In this way, an overall detail plus approximation describes each new state vector and input vector, which allows the WKF to simultaneously estimate and decompose state variables. The wavelet‐based multimodel Kalman filter (WMKF) is a multimodel Kalman filter (MKF), in which the Kalman filter has been substituted for a WKF. The WMKF then obtains M estimated state vectors. Next, the M state‐estimates, each of which is weighted by its possibility that is also determined on‐line, are combined to form an optimal estimate. Validations conducted for the Wu‐Tu watershed, a small watershed in Taiwan, have demonstrated that the method is effective because of the decomposition of wavelet transform, the adaptation of the time‐varying Kalman filter and the characteristics of the multimodel method. Validation results also reveal that the resulting method enhances the accuracy of the runoff prediction of the rainfall–runoff process in the Wu‐Tu watershed. Copyright © 2004 John Wiley & Sons, Ltd.     

数值天气预报———另类途径的必要性和可行性

通过讨论省 (甚至地、市) 气象部门要不要开展数值天气预报工作的问题, 认为不是所有的地方都要开展, 只是那些希望搞科研型业务、迫切要求提高当地高影响天气的预报准确率的地方要开展。对于如何开展的问题, 提出不是去重复类似于主流途径的做法, 而是开辟另类途径, 并阐述了另类途径的内容、方法和意义。强调开展另类途径无需构建模式 (这是非常困难的工作), 只需运转现成的模式, 借助所关心的现象的历史数据来改造现成模式, 使之本地化, 是完全可行的。     

Eco-environmental impact assessment of pre-leisure beach nourishment on the benthic invertebrate community at Anping coast

In recent years,owing to global warming and the rising sea levels,beach nourishment and groin building have been increasingly employed to protect coastal land from shoreline erosion.These actions may degrade beach habitats and reduce biomass and invertebrate density at sites where they were employed.We conducted an eco-environmental evaluation at the Anping artificial beach-nourishment project area.At this site,sand piles within a semi-enclosed spur groin have been enforced by use of eco-engineering concepts since 2003.Four sampling sites were monitored during the study period from July 2002 to September 2008.The environmental impact assessment and biological investigations that we conducted are presented here.The results from this study indicate that both biotic(number of species,number of individual organisms,and Shannon-Wiener diversity) and abiotic parameters(suspended solids,biological oxygen demand,chemical oxygen demand,dissolved inorganic nitrogen,dissolved inorganic phosphorus,total phosphorus,total organic carbon,median diameter,and water content) showed significant differences before and after beach engineering construction.Biological conditions became worse in the beginning stages of the engineering but improved after the restoration work completion.This study reveals that the composition of benthic invertebrates changed over the study period,and two groups of organisms,Bivalvia and Gastropoda,seemed to be particularly suitable to this habitat after the semi-enclosed artificial structures completion.     

Distribution of contaminants in biota and sediments in the Musquash Estuary, Atlantic Canada, marine protected area site initiative and contaminant exclusion zone

The Musquash Estuary, one of the last ecologically intact estuaries in New Brunswick, has been designated an area of interest for a marine protected area (MPA) under the Oceans Act. The area has been assessed for contaminant background levels as required for establishing MPA environmental quality. American lobster (Homarus americanus), blue mussel (Mytilus edulis) and sediments were collected for assessing contaminant levels and distribution in the harbour. Levels of contaminants from the indicator species and the abiotic component have shown: (1) two extremes of high and low Cu and Ag in lobster from the area; and (2) lower metal levels in inner Musquash Harbour sediments and mussels than in those from the harbour mouth. These suggest that deposition of contaminants into the Musquash MPA site was due to transport of contaminants by coastal currents from upstream coastal industrial activities. This reverse trend with higher contaminant levels in the biotic and abiotic components in the outer harbour than in the inner harbour differs from a contaminated harbour and suggests that a contaminant exclusion zone should be considered for controlling contamination from nearby coastal and estuarine industrial sites to protect the sensitive habitats within the marine protected area.     

Earthquake-induced landslide hazard and vegetation recovery assessment using remotely sensed data and a neural network-based classifier: a case study in central Taiwan

A catastrophic earthquake with a Richter magnitude of 7.3 occurred in the Chi-Chi area of Nantou County on 21 September 1999. Large-scale landslides were generated in the Chiufenershan area of Nantou County in central Taiwan. This study used a neural network-based classifier and the proposed NDVI-based quantitative index coupled with multitemporal SPOT images and digital elevation models (DEMs) for the assessment of long-term landscape changes and vegetation recovery conditions at the sites of these landslides. The analyzed results indicate that high accuracy of landslide mapping can be extracted using a neural network-based classifier, and the areas affected by these landslides have gradually been restored from 211.52 ha on 27 September 1999 to 113.71 ha on 11 March 2006, a reduction of 46.24%, after six and a half years of assessment. In accordance with topographic analysis at the sites of the landslides, the collapsed and deposited areas of the landslide were 100.54 and 110.98 ha, with corresponding debris volumes of 31,983,800 and 39,339,500 m³. Under natural vegetation succession, average vegetation recovery rate at the sites of the landslides reached 36.68% on 11 March 2006. The vegetation recovery conditions at the collapsed area (29.17%) are shown to be worse than at the deposited area (57.13%) due to topsoil removal and the steep slope, which can be verified based on the field survey. From 1999 to 2006, even though the landslide areas frequently suffered from the interference of typhoon strikes, the vegetation succession process at the sites of the landslides was still ongoing, which indicates that nature, itself, has the capability for strong vegetation recovery for the denudation sites. The analyzed results provide very useful information for decision-making and policy-planning in the landslide area.     

一种新型人工“流体包裹体”：融合二氧化硅毛细管技术

利用融合二氧化硅毛细管技术制作了纯H2O体系、纯CO2体系、H2O-NaCl体系和H2O-CO2体系的人工包裹体样品,并对样品进行了显微测温和激光拉曼光谱测试工作。实验结果显示毛细管样品中的流体成分具有代表性,而且常规的流体包裹体显微测温和显微激光拉曼光谱分析技术完全适于毛细管样品的测试。对样品的显微测温和拉曼光谱研究...     

Pseudopotential approaches to the structural energies of crystalline solids and solid surfaces

It is now feasible to predict accurately the structural energies of solids and solid surfaces from first principles computational techniques based on pseudopotential theory. We illustrate these techniques for several prototypical systems. We predict structural properties for binary crystalline systems of the form: A^NB^8–N where (A, B) are simple metals and metalloids and N is the number of valence electrons on A. We illustrate the chemical forces responsible for stabilizing rocksalt, zinc blende, and white tin structures as a function of pressure. Also we demonstrate the utility of these techniques for predicting the surface properties for insulators and transition metals.     

青藏高原冻土区域的相干特性分析

由季节性的冻胀和融沉导致的地表变形是在多年冻土区域进行工程施工的最主要危害, 青藏铁路建设和维护中的一个主要问题就是如何监测冻土的形变. 利用北麓河地区的ASAR数据, 联系冻土的相关变化规律, 对于冻土区域的相干特性进行了分析. 通过对不同自然地物的相干性进行对比分析, 发现冻土区域地物的相干性不仅与地物特性相关, 同时也与冻土的冻结和融化密切相关. 不同时间段干涉对的相干性的差别反映了冻土在不同季节的变化规律. 青藏铁路和公路在不同空间基线和时间基线上的相干性表现, 为该区域的稳定散射体的选择提供了一种可能, 对于进行北麓河区域的冻土形变的时间序列分析具有重要的指导意义.