长城站与新乡短波通信试验与传播方位研究

本文首先简要介绍了1985年12月至1986年3月南极长城站与新乡的短波通信效果,可通信的时段与频段,并将频段与计算的MUF进行了比较.结果表明,经过南极区的短大圆路径的通信频段上限与计算的MUF基本相符;经过北极的长大圆路径的通信频段上限与计算的MUF有偏差.其次详细介绍了在1986年1月和2月进行的传播方位测量结果.在南极长城站至新乡电路上沿大圆路径传播是主要的,而在一定时间内存在着一些非大圆路径传播.经分析研究,我们认为构成非大圆路径传播的主要原因是地表的散射,而且较强的天线副瓣和较小的电离层吸收有助于非大圆路径的形成.     

福建闽侯十八重溪的旅游资源特色与开发设想

福建闽侯十八重溪的旅游资源特色与开发设想王绍鸿，曾从盛，吴学忠，俞鸣同，杨建明（福建师范大学地理研究所）１９９１年１０月至１９９３年９月，我们参照“中国旅游资源普查规范（试行未定稿）”，对福建省闽侯十八重溪的旅游资源进行调查，并对其进行评价，提出开发...     

珠海市新型冠状病毒肺炎聚集发生的时空特征及传播路径

利用珠海市卫生健康局公开发布的98例新型冠状病毒肺炎病例流行病学调查数据，通过26个疫情聚集单元的时空特征分析和4类典型传播路径的案例剖析，深入探讨了珠海市新型冠状病毒肺炎聚集发生的时空规律和传播路径。结果表明：1）珠海的疫情发展与武汉的人口流动与管控密切相关，由于管控及时，目前仍以疫源区直接输入和家庭聚集扩散为主要传播方式，在有限范围内扩散。2）存在输入一代家庭聚集传播、输入一代非家庭聚集传播、输入二代家庭聚集传播、输入二代非家庭聚集传播4种不同的传播路径，且以第一种为主要方式，但非家庭聚集传播的路径复杂，应加强流行病学调查和防控。3）对输入性病例从输入到发病的滞后周期以及聚集单元最长发病时间间隔来看，有少部分病例或携带者可以突破14 d限制，应警惕目前普遍采用的14 d隔离措施可能存在的风险。     

南极中山站1991年地磁静日Sq变化

本文了分析１９９１年太阳活动峰年南极中山站地磁静日Ｓｑ变化，结果表明：１）地磁静日Ｓｑ变化叠加很多扰动。Ｓｑ场是由Ｓ０ｑ场和Ｓｐｑ场所组成。２）Ｓｏｐ场变化比较规则，其极昼月的变幅比极夜月大很多。在极昼月Ｓ０ｑ（Ｈ）变化出现有双峰图象。Ｓｏｐ场主要是由高结局度极区电离层Ｓｑ电流体系所控制。     

南极春季中山站地区大气臭氧和NO2的变化特性

利用可见／紫外差分吸收光谱学方法，在１９９１年南极臭氧洞期间对中山站地区的大气臭氧和ＮＯ２含量进行了测量。分析结果指出，对中山站地区面言，１９９１年大气臭氧含量的迅速减少开始于８月中旬，到１０月３日达最低值，并很于１０月７日恢复到正常值。     

足迹留边陲 桃李遍四方──忆严德一教授

足迹留边陲桃李遍四方──忆严德一教授毛必林（杭州大学地理系杭州：３１０００７）１９９１年３月１５日，原杭州大学地理系主任严德一教授不幸逝世，享年８３岁。我们为失去了一位素负重望的地理学家而深感悲痛！严德一教授１９０８年生于江苏省泰兴县严徐庄。少年时期...     

考虑非期望产出的中国省际海洋经济效率测度及时空特征

基于考虑非期望产出的SBM模型,对2001~2012年沿海11个省市区（不含香港、澳门、台湾地区）的海洋经济效率进行了测度,并对其时空特征进行分析。研究发现：① 不考虑非期望产出的效率值要明显高于考虑非期望产出的效率值,非期望产出对于海洋经济效率具有明显影响。② 2001年以来海洋经济效率演变分为波动下降（2001~2008）和缓慢上升（2009~2012）两个阶段;区域差距呈先缩小后扩大的趋势。③ 空间上呈现由南北高、中部低的格局向以天津、上海、广东为中心的三极格局演进的趋势;省际变化特征各异。最后对海洋经济效率的影响机制进行了解释,并提出了提高海洋经济效率的实现路径。     

南极春季中山站地区大气臭氧和NO_2的变化特性

利用可见／紫外差分吸收光谱学方法，在１９９１年南极臭氧洞期间对中山站地区的大气臭氧和ＮＯ２含量进行了测量。分析结果指出，对中山站地区而言，１９９１年大气臭氧含量的迅速减少开始于８月中旬，到１０月３日达最低值，并很快于１０月７日恢复到正常值。大气臭氧和ＮＯ２的变化有很好的正相关性，相关系数达０．６９；臭氧洞期间，ＮＯ２含量一直处于低值，且层的高度较高。这表明１９９１年春季中山站地区臭氧含量的减少不是由奇氮的的催化损耗过程所致     

南极中山站1991年地磁静日S_q变化

本文分析了１９９１年太阳活动峰年南极中山站地磁静日Ｓｑ变化，结果表明：１）地磁静日Ｓｑ变化叠加有很多扰动。Ｓｑ场是由Ｓ０ｑ场和Ｓｐｑ场所组成。２）Ｓ０ｑ场变化比较规则，其极昼月（夏季）的变幅比极夜月（冬季）大很多。在极昼月Ｓ０ｑ（Ｈ）变化出现有双峰图象。Ｓ０ｑ场主要是由高纬度极区电离层Ｓｑ电流体系所控制。３）Ｓｐｑ场的变化形态没有昼夜之分；它的变化强度为冬季小、夏季大。Ｓｐｑ场源主要是依赖于场向电流和电离层电导率。４）Ｓ０ｑ（Ｚ）变化比Ｓ０ｑ（Ｈ）变化要大，特别是在极夜的冬季，Ｓ０ｑ（Ｚ）的变幅比Ｓ０ｑ（Ｈ）大２／３倍。本文对北京地磁中心台磁静日资料也一并进行了分析。Ｓｑ变化主要是由北半球中、低纬电离层Ｓｑ电流体系所引起的     

南极普里兹湾及邻近海域二氧化碳的分布及其海气通量

本文根据１９９１年１２月至１９９２年１月在普里兹湾及其邻近海域所作的现场观测，采用红外分析法测定了表层水和大气ＣＯ２分压，结果表明，表层水ＰＣＯ２的分布大致呈近岸低、远岸高的特征，其分布变化主要受生物活动控制。利用通量计算模式，估算出ＣＯ２在调查海域的平均海－气通量为－７１．９ｇ／（ｍ２ａ），通量的可能误差主要来自与风速有关的交换系数。     

EXPERIMENT OF SHORT WAVE COMMUNICATION AND THE INVESTIGATION OF THE PROPAGATION BEARINGS BETWEEN THE GREAT WALL STATION AND XINXIANG

The distance from the Great Wall Station (62.2°S, 58.9°W) to Xinxiang (35.3°N, 113.8°E) is 16981 kin. The path passes through the polar cap absorption region and the auroral absorption zone, and it is across the equator. In this paper firstly the effects of short wave communication and usable time blocks and frequency ranges between the Antarctic Great Wall Station and Xinxiang from December 1985 to March 1986 are introduced. The comparison between the usable frequency ranges with the estimated MUF is made. The upper limit of frequency ranges of communication along the short great circle path basically agrees with the MUF but there is difference between them along the long great circle path. Secondly, the result of the propagation bearings experiment in January to February 1986 is introduced in more detail, The propagation along the great circle path from the Great Wall Station to Xinxiang is the main propagation mode. But the propagation along non great circle paths occurs at times between Great Wa     

On the retrieval of pure path velocities from great circle data

Summary. Synthetic great circle Rayleigh wave phase velocities are generated from a 3-D upper mantle model for two great circle distributions: a uniform random distribution and an experimental distribution arising from a real set of sources and receivers. Given a tectonic regionalization, the retrieval of the pure path velocities from these great circle data sets leads to a strongly biased solution when the uniform distribution is used, whereas the results from the experimental distribution are closer to the true values. An analysis of the data importances and the information distribution in the data indicates that the great circles introduce coupling between tectonic regions; thus the degeneracy of the solution inherent in great circle data cannot be completely overcome by introducing a tectonic regionalization. It is shown that a satisfactory solution is obtained by selecting data as pure as possible, i.e. data that over-sample one tectonic region without oversampling the others. This condition is better fulfilled by the experimental distribution than by the uniform distribution.     

Validity of the great circular average approximation for inversion of normal mode measurements

Summary. Synthetic seismograms based upon first-order perturbation theory are analysed to test the validity of assumptions which form the basis of current velocity inversion procedures. It is found that the lowest order geometrical optics approximation, namely that measured normal mode eigen-frequencies reflect the average structure underlying the source–receiver great circle path, becomes less valid near nodes in the source radiation pattern and near the surface wave foci at the source and its antipode. These failures are a consequence of singlet interference within an isolated normal mode multiplet. The technique of determing frequency by fitting a single resonance peak to a multiplet yields results which agree well with the first-order theory for slow and fast paths where excitation is dominated by one pair of singlets but on intermediate paths where singlet interference is more of a problem, agreement is not as good. Inversion of small data sets is particularly sensitive to frequency fluctuations near radiation nodes, while larger sets are influenced more by antipodal deviations from geometrical optics. The latter leads to inversions which fail to recover the short wavelength structure of the starting model. Basing inversions directly upon first-order theory shows promise of improving recovery of short wavelengths.     

HF FIELD STRENGTH MEASUREMENTS OVER THE VERY LONG DISTANCE

It was ascertained that there is a great margin between the theoretical values and experimental medians of the field strength of RWM and RID signals during high solar activity period at Chinese Great Wall Station on Antarctica. The calculated values are, on average, less than the experimental, especially on the propagation path between RID and Antarctica. The field strength by the experiment may be used as the basic data for the research of HF propagation over the very long distance. Because of the large deviation it seems to be necessary to study HF propagation over the very long distance in details, especially the propagation model.     

研究中国城市化理论学派述评

中国城市化具有独特性,自70年代以来一直成为学术界的研究热点之一.文中通过对各有关研究的比较和总结,归纳出5种最具代表性和影响力的学说,即反城市主义说、工业战略说、城市二元体系和工农业均衡发展说、工业化和城市偏爱说以及综合说,并对各学说进行了评述,指出中国在面临社会经济结构全面转型的历史时期,极有必要借鉴他人的研究方法和成果去建立自己的新理论.     

发达国家生态发展道路的比较与透视

＂先污染、后治理＂是发达国家生态发展道路的共同特点。在概述发达国家生态发展道路演变历程的基础上,对其进行历史比较,总结出欧盟、美国和日本在生态发展道路上的不同特征,并对欧、美、日生态发展道路的内涵和本质进行分析,从而提出中国在生态发展中应该注意的问题：借鉴发达国家的生态治理经验,在科学发展观的指导下,采用以绿色城市化、绿色空间布局、横向布局与流域开发为基础的新的发展方式,实现具有中国特色的生态文明。     

天山乌鲁木齐河源空冰斗中分选环的观测与研究

本文研究了天山乌鲁木齐河源空冰斗中不同发育阶段的分选环的特征和同一发育阶段分选环的差异。对各阶段的分选环进行了形态、粒度、含水量、冻胀情况、砾石分选、组构以及用木桩垂直打入地下的观测和分析。     

An extension of GIS-based least-cost path modelling to the location of wide paths

The computation of least-cost paths over a cost surface is a well-known and widely used capability of raster geographic information systems (GISs). It consists in finding the path with the lowest accumulated cost between two locations in a raster model of a cost surface, which results in a string-like, thin and long sequence of cells. In this article, a new extension of raster-based least-cost path modelling is proposed. The new modelling approach allows the computation of paths or corridors with a fixed width, larger than one cell. These swaths are called wide paths and may be useful in circumstances where the detail level of the raster cost surfaces is higher than the width of the desired path or corridor. The wide path model presented in the article is independent of the choice of least-cost algorithms, because the transformation from regular to wide paths is applied to the construction of nodes and edges of an induced graph. The article gives the foundations and discusses the particularities of such paths, regardless of the imposed width, and explores the difference from the usual least-cost path model. Test cases were included, one hypothetical and the other with real data. The results are coherent and indicative of the applicability of wide paths.     

北部湾经济圈的形成和开发设想

随着中越关系的改善以及南昆铁路即将通车,大西南与北部湾的联系日渐密切。以北部湾 中心,将迅速形成区域合作体系－经济圈。文中分析了北部湾的战略区位及其形成经济圈的区域环境的条件,认为其区位优越,且无论是国际大环境还是区域内部小环境都有利于经济圈的形成;还分析了北部湾经济圈形成所必需的物质基础,认为其具有大储量的现代共业资源、曲折的海岸线和众多的优良港湾、丰富的热带来势带作物资源和海洋生物资源以及特有