Regional Features of Vapor Transfer and Precipitation Distributed in Northwest China

This article investigates regional distribution features of rainfall and vapor transport in Northwest China during 1961-2002, achieving that: (1) Three climate zones in this vast region differ in trends of annual precipitation, with rainfall in the westerly belt (denoted as zoneWB) exhibiting an increasing trend from the 1970s, rainfall in the East Asian monsoon belt (denoted as zoneMB) displaying a decreasing trend in the study period and the Qinghai Plateau zone (denoted as zoneQP) precipitation fluctuating roughly around the mean; (2) The net vapor fluxes (NVF) in zoneWB and zoneQP show an increasing trend as opposited to zoneMB, for which the reason may lie behind that the NVF increase in zoneWB and zoneQP is attributed to pronounced decrease in deficit of westerly NVF, whereas the decrease in zoneMB NVF is ascribed to the significant drop in meridional vapor transfer; (3) ZoneWB rainfall and atmospheric vapor transport change abrupt in 1990 and 1985, respectively, without such happening in zoneMB and zoneQP; (4) ZoneWB rainfall increase occurs when atmospheric vapor budget/NVF increases, so that the latter has to occur ahead of the former; zoneMB rainfall decrease relates to the decrease in atmospheric vapor budget after the 1990s,leading to (more and even) successive droughts in the east of Northwest China on a synchronous basis except zoneQP of which the precipitation factors include river evaporation, glaciers, and snow cover in addition to atmospheric vapor.     

Local Oscillator Distribution Using A Geostationary Satellite

A satellite communication system suitable for distribution of local oscillator reference signals for a widely spaced microwave array has been developed and tested experimentally. The system uses a round-trip correction method to remove effects of atmospheric fluctuations and radial motion of the satellite. This experiment was carried out using Telstar-5, a commercial Ku-band geostationary satellite. A typical Ku-band satellite has uplink and downlink capacity at 14–14.5 GHz and 11.7–12.2 GHz, respectively. For this initial experiment, both earth stations were located at the same site to facilitate direct comparison of the received signals. The local oscillator reference frequency was chosen to be 300 MHz and was sent as the difference between two Ku-band tones. The residual error after applying the round trip correction has been measured to be better than 3 ps for integration times ranging from 1 to 2000 s. For integration times greater than 500 s, the system outperforms a pair of hydrogen masers with the limitation believed to be ground-based equipment phase stability. The idea of distributing local oscillators using a geostationary satellite is not new; several researchers experimented with this technique in the eighties, but the achieved accuracy was 3 to 100 times worse than the present results. Since then, the cost of both leased satellite bandwidth and the Ku-band ground equipment has dropped substantially and the performance of various components has improved. An important factor is the availability of narrow bands which can be leased on a communications satellite. We lease three 100 kHz bands at approximately one hundredth the cost of a full 36 MHz-wide transponder. Further tests of the system using terminals separated by large distances and comparison tests with two hydrogen masers and radio interferometry of astronomical objects are needed.     

The method of a two-point conditional column density for estimating the fractal dimension of the distribution of galaxies

We suggest a new method for estimating the fractal dimension of the spatial distribution of galaxies: the method of selected cylinders. We show the capabilities of this method by constructing a two-point conditional column density for galaxies with known redshifts from the LEDA database. The fractal dimension of a sample of LEDA and EDR SDSS galaxies has been estimated to be 2.1±0.1 for cylinder lengths of 200 Mpc. A major advantage of the suggested method is that it allows scales comparable to the catalog depth to be analyzed for galaxy surveys in the form of conical sectors and small fields in the sky.     

北半球平流层臭氧的时空分布特征

利用1963－1985年北半球的平流层臭氧观测资料，采用自然平交分解方法，初步分析了北半球、特别是东亚地区大气臭氧层的时空分布特征。结果表明：（1）北半球大气臭氧的空分间分布可能与下垫面的性能有关；（2）东亚地区大气臭氧的时间分布主要具有2年和11年变化的周期特征，这与太阳黑子的准2年和准11年变化有一定的对应关系；（3）北美地区的臭氧变化则主要包含4年和7年的周期变经成分。     

Distribution of free electrons in the galactic plane

A method is proposed for constructing a map of the electron density distribution in the galactic plane. Data on the dispersion measures DM of more than 1500 pulsars and their distances, found by an independent method, are used. The independent distances of the pulsars are estimated using an empirical relation of the form L=γP ^α Ṗ ^β W ^δ between the radio luminosity L of the pulsars and their periods P, the rate of change Ṗ. of their periods, and the half width W of their pulses. A map of the electron density distribution in the galactic plane within a ±400 pc layer is provided. __________ Translated from Astrofizika, Vol. 49, No. 2, pp. 277–287 (May 2006).     

A bimodal four‐parameter lognormal linear model of soil water repellency persistence

Soil water repellency may be characterized in terms of the delayed infiltration time of a water droplet resting on the soil surface, which is, water drop penetration time (WDPT), or repellency persistence. Such repellency persistence varies nonlinearly with soil water content (θ_g), although no models have been proposed to reproduce the variation of WDPT with θ_g in soils. Dynamic factor analysis (DFA) is used to identify two common patterns of unexplained variability in a scattered dataset of WDPT versus θ_g measurements. A four‐parameter lognormal distribution was fitted to both common patterns obtained by DFA, and these were combined additively in a weighted multiple linear bimodal model. We show how such an empirical model is capable of reproducing a large variety of WDPT versus θ_g curve shapes (N = 80) both within a wide range of measured WDPTs (0–17 000 s) and for samples with organic matter content ranging from 21·7 to 80·6 g (100 g)^?1. Copyright © 2009 John Wiley & Sons, Ltd.     

集聚型空间点模式结构信息提取研究

空间点模式是一个2维离散点集,点集中的每一个元素代表地球表面一个点状目标的空间位置。当2维离散点集具有集聚特征时,称其为集聚型空间点模式,它与空间聚类、制图综合和空间分析的许多具体应用紧密相关。如何提取集聚型空间点模式的结构信息(集聚子群的个数和对应的集聚中心)是其中尚未彻底解决的问题。作者以几何概率为理论基础,提出测度正方形区域内2维离散点集分布特征的H函数并推导其解析表达式,运用H函数设计和实现了集聚型2维离散点集结构信息提取的通用算法。利用该算法处理一个由居民地坐标数据得到的具有集聚特征的空间点模式,提取出其结构信息并进行可视表达。分别以该空间点模式中的各离散点为顶点和发生元生成Delaunay三角网和Voronoi图,在Delaunay三角网中保留面积最小的前1/10、前1/100三角形的顶点,在Voronoi图中保留面积最小的前1/10、前1/100邻近多边形的发生元,将可视表达的点集结构信息分别与依据Delaunay三角网和Voronoi图得到的结果进行对比分析。结果表明,运用H函数能够有效地提取出集聚型空间点模式的全局性结构信息,而Delaunay三角网和Voronoi图虽然能够反映其局部密度,但在提取全局结构信息时存在局限性。     

Coherent Chemical Variation Trends of the 55-25 Ma Magmatic Rocks in SE Tibet:N-S Direction Lithospheric Stretching of Eurasia during Early Stage of India-Eurasia Collision

The progressive indentation of India into Eurasia generated an E–W-trending orthogonal collision belt and a N–S-trending oblique collision belt. Compiling available data reveals that ～70% of the Cenozoic igneous rocks in eastern and southeastern Tibet are concentrated within an ENE-trending, ～550-km long and ～250-km wide magmatic zone(CMZ) that once separated the orthogonal and oblique collision belts. The Latitude 26°N Line is now its southern boundary. The onset timing of magmatism of the CMZ ...     

我国地质文化村（镇）空间分布特征及影响因素研究

地质文化村（镇）是地质文化科普的重要窗口,也是所在区域经济社会发展的重要依托,对其空间分布特征及影响因素的研究对我国地质文化村（镇）的进一步评定和可持续发展具有重要意义。运用最邻近指数、不平衡指数、核密度分析和地理探测器方法,对我国50个地质文化村（镇）的空间分布特征及其影响因素进行研究,研究表明：①地质文化村（镇）的空间分布类型为随机分布型;②各省（市、区）地质文化村（镇）数量差异明显,空间分布不均衡,呈“东多西少”格局;③地质文化村（镇）形成1个高密度核心区、2个次高密度集聚区、1条核心延长带;④影响我国地质文化村（镇）空间分布格局的因素由特色地质资源、自然条件以及社会经济与人文资源3个一级指标构成,其中社会经济与人文资源对地质文化村（镇）空间分布影响最大且效果显著。在今后地质文化村（镇）的评定建设中,应加强中西部地区地质文化村（镇）的建设和申报;适当给予中西部地区地质文化村（镇）评定倾斜;加大地质文化村（镇）宣传力度;充分发掘地质特色及民俗文化,加强地质文化村（镇）与文化的融合。