安徽柯村A型花岗岩岩墙群地质地球化学特征及构造环境

柯村岩墙群岩石具文象结构，地球化学上具富硅、富碱、富Ｇａ、Ｚｒ、Ｎｂ、Ｆ，低铝、贫水和Ｂａ、Ｓｒ特征。在多种判别图上，均投影在Ａ型花岗岩区。根据岩石地球化学特征和产出构造环境分析，柯村岩墙群属非造山区裂图１柯村碱性花岗岩岩墙群地质略图Ｆｉｇ．１Ｔｈｅａｌｋａｌｉｎｅｇｒａｎｉｔｅｄｙｋｅｃｌｕｓｔｅｒ，Ｋｅｃｕｎ．谷Ａ型花岗岩。     

Characteristics of grassland degradation and driving forces in the source region of the Yellow River from 1985 to 2000*

The source region of the Yellow River is located in the middle east of the Tibetan Plateau in northwest China. The total area is about 51,700 km2, mainly covered by grassland (79%), unused land (16%) and water (4%). The increasing land utilization in this area has increased the risk of environmental degradation. The land use/cover data (1985 and 2000) provided by the Data Center of Resources and Environment in the Chinese Academy of Sciences were used to analyze the land cover change in the source region of the Yellow River. DEM (1:250,000) data, roads and settlement data were used to analyze the spatial characteristics of grasslands degradation. The ArcGIS 9 software was used to convert data types and do the overlay, reclassification and zonal statistic analysis. Results show that grassland degradation is the most important land cover change in the study area, which occupied 8.24% of the region’s total area. Human activities are the main causes of the grassland degradation in the source region of the Yellow River: 1) the degradation rate is higher on the sunny slope than on the shady slope; 2) the grassland degradation rate decreases with an increase in the elevation, and it has a correlation coefficient of -0.93; 3) the nearer to the settlements the grassland is, the higher the degradation rate. Especially within a distance range of 12 km to the settlements, the grassland degradation rate is highly related with the distance, with a coefficient of -0.99; and 4) in the range of 4 km, the degradation rate decreases with the increase of distance to the roads, with a correlation coefficient of -0.98. Besides some physical factors, human activities have been the most important driving forces of the grassland degradation in the source region of the Yellow River since 1985. To resolve the degradation problems, population control is essential, and therefore, it can reduce the social demand of livestock products from the grassland. To achieve sustainable development, it needs to improve the management of grassland ecosystem.     

T213L31全球中期数值天气预报系统2m温度预报误差源分析

T213L31全球中期数值天气预报系统的2m温度预报存在系统性偏低的问题，对业务预报影响很大，针对这一问题就产生原因对模式系统进行分析定位。经过一系列分析，通过对模式地形高度与观测站地形高度的比较，以及通过采用欧洲中心与国家气象中心的陆面过程初值得到的2m温度的比较，认为2m温度的误差是由于模式地形高度与实际地形高度存在较大差异以及2m温度预报对陆面过程所需的初值如土壤湿度等的敏感而实际采用特定值代替初始场的不科学性造成的。     

Pulse-length-tolerant features and detectors for sector-scan sonar imagery

This paper presents a neural-network-based system to detect small man-made objects in sequences of sector-scan sonar images created using signals of various pulse lengths. The detection of such objects is considered out to ranges of 150 m by using an experimental sector-scan sonar system mounted on a vessel. The sonar system considered in this investigation has three modes of operation to create images over ranges of 200, 400, and 800 m from the vessel using acoustic pulses of a different duration for each mode. After an initial cleaning operation performed by compensating for the motion of the vessel, the imagery is segmented to extract objects for analysis. A set of 31 features extracted from each object is examined. These features consist of basic object size and contrast features, shape moment-based features, moment invariants, and features extracted from the second-order histogram of each object. Optimal sets of 15 features are then selected for each mode and over all modes using sequential forward selection (SFS) and sequential backward selection (SBS). These features are then used to train neural networks to detect man-made objects in each sonar mode. By the addition of a feature describing the sonar's mode of operation, a neural network is trained to detect man-made objects in any of the three sonar modes. The multimode detector is shown to perform very well when compared with detectors trained specifically for each sonar mode setting. The proposed detector is also shown to perform well when compared to a number of statistical detectors based on the same set of features. The proposed detector achieves a 92.4% probability of detection at a mean false-alarm rate of 10 per image, averaged over all sonar mode settings.     

水产试验设计的SAS实施方法

本文通过两个实例讨论水产试验设计的结果数据在ＳＡＳ系统上实施统计分析的方法。实例一考察不同温度和盐度对鲻鱼总孵化百分率的影响的带有４个丢失单元的５×６因子设计，调用ＲＳＲＥＳ过程作二次响应曲面回归分析，结果表明当温度为２７．０４℃、盐度为３１．９５‰可获得最大总孵化百分率９９．０７％；实例二调用ＮＬＩＮ过程拟合罗氏沼虾的生长曲线，由ＳＡＳ系统直接输出实测值对出生天数和预测值对出生天数的重迭散布图。     

Petrography and geochemistry of the enriched basaltic shergottite Northwest Africa 2975

We present a study of the petrology and geochemistry of basaltic shergottite Northwest Africa 2975 (NWA 2975). NWA 2975 is a medium‐grained basalt with subophitic to granular texture. Electron microprobe (EMP) analyses show two distinct pyroxene compositional trends and patchy compositional zoning patterns distinct from those observed in other meteorites such as Shergotty or QUE 94201. As no bulk sample was available to us for whole rock measurements, we characterized the fusion crust and its variability by secondary ion mass spectrometer (SIMS) measurements and laser ablation inductively coupled plasma spectroscopy (LA‐ICP‐MS) analyses as a best‐available proxy for the bulk rock composition. The fusion crust major element composition is comparable to the bulk composition of other enriched basaltic shergottites, placing NWA 2975 within that sample group. The CI‐normalized REE (rare earth element) patterns are flat and also parallel to those of other enriched basaltic shergottites. Merrillite is the major REE carrier and has a flat REE pattern with slight depletion of Eu, parallel to REE patterns of merrillites from other basaltic shergottites. The oxidation state of NWA 2975 calculated from Fe‐Ti oxide pairs is NNO‐1.86, close to the QFM buffer. NWA 2975 represents a sample from the oxidized and enriched shergottite group, and our measurements and constraints on its origin are consistent with the hypothesis of two distinct Martian mantle reservoirs: a reduced, LREE‐depleted reservoir and an oxidized, LREE‐enriched reservoir. Stishovite, possibly seifertite, and dense SiO₂ glass were also identified in the meteorite, allowing us to infer that NWA 2975 experienced a realistic shock pressure of ~30 GPa.     

浴场海水中大肠杆菌耐药性及其耐药基因研究

为了解海水浴场中大肠杆菌耐药性状况及其耐药基因分布,以大连星海浴场近岸海水样品为研究对象,分离鉴定得到41株大肠杆菌,采用K-B药敏纸片法检测其对9种常用抗生素的耐药性,并对耐药菌株中的耐药基因进行检测。结果表明:41株受试大肠杆菌菌株对四环素的耐药率最高(46%),而对氨曲南的耐药率最低(5%),大肠杆菌的多重耐药率达到34%。采用PCR方法对41株分离菌株进行四环素耐药基因检测,结果显示,仅四环素耐药基因tetA和tetB被检出,其他4种类型四环素耐药基因未被检出。大肠杆菌基因组与质粒DNA中tetA的检出率分别为34%和29%;tetB的检出率分别为2%和12%。相关性分析结果表明大肠杆菌的四环素耐药表型与四环素耐药基因的阳性检出率显著相关。     

Advances in Research on Soil Moisture by Microwave Remote Sensing in China

Soil moisture is an important factor in global hydrologic circulation and plays a significant role in the research of hydrology, climatology, and agriculture. Microwave remote sensing is less limited by climate and time, and can measure in large scale. With these characteristics, this technique becomes an effective tool to measure soil moisture. Since the 1980s, Chinese researchers have investigated the soil moisture using microwave instruments. The active re- mote sensors are characteristic of high spatial resolution, thus with launch of a series of satellites, active microwave remote sensing of soil moisture will be emphasized. The passive microwave remote sensing of soil moisture has a long research history, and its retrieval algorithms were developed well, so it is an important tool to retrieve large scale moisture information from satellite data in the future.     

Flow–stress coupled permeability tensor for fractured rock masses

In this paper a new analytical model is proposed to determine the permeability tensor for fractured rock masses based on the superposition principle of liquid dissipation energy. This model relies on the geometrical characteristics of rock fractures and the corresponding fracture network, and demonstrates the coupling effect between fluid flow and stress/deformation. This model empirically considers the effect of pre‐peak shear dilation and shear contraction on the hydraulic behavior of rock fractures and can be used to determine the applicability of the continuum approach to hydro‐mechanical coupling analysis. Results of numerical analysis presented in this paper show that the new model can effectively describe the permeability of fractured rock masses, and can be applied to the coupling analysis of seepage and stress fields. Copyright © 2008 John Wiley & Sons, Ltd.