Two suggested configurations for the Chinese space telescope

China will establish a 2-meter space-based astronomical telescope. Its main science goals are performing a sky survey for research about dark matter and dark energy, and high resolution observations. Some experts suggest that this space telescope should be installed inside the Chinese space station. In accord with this suggestion we put forward our first configuration, i.e., to adopt a coud′e system for this telescope.This coud′e system comes from the Chinese 2.16 m telescope's coud′e system, which includes a relay mirror so that excellent image quality can be obtained. In our second configuration, we suggest that the whole space telescope fly freely as an independent satellite outside the space station. When it needs servicing, for example, changing instruments, refilling refrigerant or propellant, etc., this space telescope can fly near or even dock with the core space station. Although some space stations have had accompanying satellites, the one we propose is a space telescope that will be much larger than other accompanying satellites in terms of weight and volume. On the basis of the second configuration, we also put forward the following idea: the space station can be composed of several large independent modules if necessary.     

模糊模型判识在斜坡破坏危险性分区中的应用

本文在探讨斜坡破坏危险性分区中,试用模糊模型判识方法,依斜坡演变趋势与影响因素间的关联性,进行模糊聚类和相容度的分析,从而对斜坡破坏危险性做以分级分区研究并对斜坡的环境质量做以评价。     

论岩溶水系统预报时边界条件问题

<正>七十年代以来,国内用线性渗流确定性模型对地下水系统进行数值模似(反求参数,预报人工流场),已取得丰富的成果和经验,但也存在一些问题。其中重要的问题之一是模型预报时边界条件的非确定性。对于该问题虽然有不同的解决办法,也有一些较大的分歧,至今还缺乏一套科学依据较严密的处理原则和求值方法。     

Regularity and estimation of methane emission from marshland in the Sanjiang Plain

The regularity of CH₄ emission from marshland in the Sanjiang Plain was studied by sampling in the open field and analyzing under laboratory condition, the annual emission amount is also estimated. By Grey Relatively Analysis we know that the soil temperature in the 10-cm depth of grass-root layer is close related with CH₄ emission. CH₄ emission has different kinds of diurnal emission modes:before-dawn maximum mode, night maximum mode and irregular fluctuation mode. The seasonal variation trend of CH₄ emission rates is going up steadily from May to August and dropping down from September, the maximum lies behind the maximum of temperature. CH₄ emission rates of different marshland types are different, the CH₄ emission rate of Glyceriaspiculosa — Carex marshland is always higher than that of Carex lasiocarpa marshland. The paper also studies the difference of CH₄ emission rates in different managing modes and analyzes the emission rates between China and U. S. A. The result shows: the average value of CH₄ emission rate is 17.26mg/(m²·h), the annual amount of CH₄ emission is about 0.75Tg. Supported by National Natural Sciences Foundation of China, and thank the Ecological Test Station of Mires and Wetlands in the Sanjiang Plain, the Chinese Academy of Sciences.     

Sustainable development of the seriously polluted cities in China

The environmental problems in the seriously polluted cities in China have been paid attention to by policy-makers and foreign and domestic scholars. However, it is very difficult to improve the environmental quality fundamentally due to its complexity, for example the formation of the seriously deteriorated environment. It is considered that the terminal harnessing is an important way, but the spread of high-level terminal treatment is restricted by the limit of funds and technological level. Therefore, the way for a sustainable development of the seriously polluted cities should be multiple-sided, which is to correlate the operation of environmental protection with the operation of city construction. To achieve an identity of these opposites, measures should be taken during economic development and environmental protection in every developing stage. In this paper, the authors take Benxi City as a case study.     

Empirical orthogonal modes in the Western Pacific

The method of empirical orthogonal modes has been widely used since the 1970's in physical oceanography to study and rebuild vertical structures of ocean dynamic factors. Because of the dominance of the low modes, the dynamic profile data can be largely reduced. Up to now, all expressions of empirical orthogonal modes are numerical. In this study, an analytic expression for empirical orthogonal ocean modes is constructed for convenient use whereby any numerical expressions can be repeated. The features of the normal modes decomposed from the buoyance frequency profiles obtained in October of 1986, 1987 and 1988 by the R/VScience 1 in the western Pacific are quantitatively examined in this study. Contribution No. 1724 from the Institute of Oceanology, Academia Sinica     

Reduced growth in hybrid tilapia (Oreochromis mossambicus ×O. Niloticus) at intermediate stocking density

Hybrid tilapia were reared at densities of 1, 5 or 10 fish per tank for four weeks. Mortality was 0 at 1 and 10 fish per tank, but was 25% at 5 fish per tank. Specific growth rate was highest at 1 fish per tank, and lowest at 5 fish per tank. The lower growth rate at the intermediate stocking density was associated with reduced feed efficiency, but there was no reduction in feed intake or digestibility. The results suggested increased metabolic cost caused by aggressive behaviour at intermediate stocking density, which can be suppressed by a further increase in density. This project was financially supported by the State Key Laboratory of Freshwater Ecology and Biotechnology of China and by Shanghai Fisheries University (Project SFU. 200003).     

Detecting Holocene movements of the woodland–steppe ecotone in northern China using discriminant analysis

Discriminant functions link vegetation zones and surface pollen along the woodland–steppe ecotone in northern China. These links were utilised to reconstruct palaeovegetation using fossil pollen data from four lake sediment sites within the ecotone. Holocene movements of the vegetation zones were derived from the above results and were interpreted as the results of climatic, topographic and edaphic factors. This study shows that climatic change was the driving factor for ecotonal movement, but that the positions of vegetational zones were nevertheless controlled by topographical and edaphic conditions, and consequently boundaries between different vegetational zones responded individualistically. Copyright © 2001 John Wiley & Sons, Ltd.     

Current Flows in Pulsar Magnetospheres

The global structure of current flows in pulsar magnetosphere is investigated, with rough calculations of the circuit elements. It is emphasized that the potential of the critical field lines (the field lines that intersect the null surface at the light cylinder radius) should be the same as that of interstellar medium, and that pulsars whose rotation axes and magnetic dipole axes are parallel should be positively charged, in order to close the pulsar's current flows. The statistical relation between the radio luminosity and pulsar's electric charge (or the spindown power) may hint that the millisecond pulsars could be low-mass bare strange stars.     

基于MVO优化神经网络的GNSS高程异常拟合方法

针对普通神经网络的梯度消失和易陷入局部极值的问题,提出一种基于多元宇宙优化算法(multi-verse optimizer, MVO)的BP神经网络优化方法(MVO-BP),利用MVO全局寻优的特性求取BP神经网络各层之间可靠的神经元阈值与连接权,从而使神经网络预测模型具备更高的预测精度。建立基于MVO-BP算法的GNSS高程异常拟合预测模型,并采用实际工程中少量高程异常数据进行算法可行性检验。结果表明,相较于常规的BP神经网络法及多面函数法,MVO-BP法精度更高、适用性更强,可为实际工程测量中正常高的求取提供参考。