Rockfalls and rockfall inventory data: Some observations from surprise valley,Jasper National Park,Canada

The major controls of rockfall activity are divided into two interacting groups. (a)Climatic factors which, through their control of temperatures and the availability and state of water, are primary controls of rockfall trigger mechanisms. (b) Geologic factors which, via cliff form (plan, profile, dissection etc.) and the character and availability of materials, influence the type, spatial distribution and intensity of rockfall activity. Detailed examination of these controls suggest that both seasonal and daily patterns of rockfall activity can vary markedly over a very small area. The implications of this variability for the design and interpretation of rockfall inventories are discussed using sample data from Surprise Valley, Jasper National Park, for the period from May-October 1969. On a seasonal basis rockfall activity showed a major spring peak with secondary maxima in the fall and associated with major summer storms. Two sites of differing aspect and morphology were studied in more detail revealing marked differences in the mean hourly frequency (0·94:0·20), mean hourly probability (0·40:0·16, hours with rockfall/hours observed) and daily pattern of rockfall activity. The west facing site showed equal hourly probability of rockfalls from 10⁰⁰ to 20⁰⁰ hr whereas the east facing slope had a greater hourly probability when it was in the sun (11⁰⁰ 14⁰⁰hr) than in the shade (14⁰⁰-19⁰⁰hr). The differences in rockfall frequency and probabilities reflect the physical characteristics of the individual sites whereas the daily pattern of rockfalls is related to microclimate. These results suggest that if future inventory studies are to make a significant contribution, they must be carefully designed field experiments in which. (i) Data are restricted to the study or comparison of single continuously observed sites. (ii) Study sites and/or data periods are carefully selected to isolate and investigate specific controls e.g. the influence of cliff form, aspect, periods of rainfall etc. on rockfall patterns. (iii) Good on-site microclimate data are available. Also comparison of frequency measures based on the arithmetic mean should be avoided since the distribution of rockfalls per hour closely follows a Poisson distribution with occasional high values which unduly influence the value of the arithmetic mean. It is suggested that rockfall probabilities, based on the binary decision of whether or not a rockfall occurs in a given period, are a more useful measure for daily patterns of rockfall activity.     

一种高效的迭代OFDM频偏估计算法

提出了一种改进的正交频分复用（Orthogonal Frequency Division Multiplexing,OFDM）载波频率偏移估计算法并通过MATLAB进行仿真.仿真结果表明算法对小数载波频率偏移估计精度高并且其算法复杂度低.     

OFDM基带处理系统的设计与实现

阐述了适合高速无线数据传输的正交频分复用(OFDM)调制方式的基本原理及调制解调的快速傅立叶变换(FFT)实现,并给出OFDM基带处理系统的结构图和硬件模块框图。     

Mismatch between biological,exploitation, and governance scales and ineffective management of sea urchin (Paracentrotus lividus) fisheries in Galicia

The spatial structure of fishery resources influences stock dynamics and finally the fishery. Therefore, this aspect should be included as a key topic in the assessment and management of fisheries. The fishery of the sea urchin Paracentrotus lividus in Galicia has been used as case study to demonstrate how the mismatch between biological, fishery and management scales causes failures in the governance, giving rise to over-exploitation. P. lividus is spatially distributed in nested biological units: patches, micro-stocks, local populations and metapopulations. Fishing operations are local exploiting micro-stocks; however management units in Galician comprise usually more than one local population. This pattern allows the depletion of several micro-stocks without any short-term signals in the exploitation rates over the complete managed territory. Management units should be redefined according to the boundaries of the local populations. In addition, the implementation of reserve networks or a rotation system could allow to effectively managing the resource at a fine-scale. Any of both regulations could also compensate the inverse density dependence that regulates recruitment and fecundity in this species.     

用于测量圆顶视宁度的微温脉动仪的研制

为评价云南天文台丽江2.4m望远镜的圆顶视宁度,研制了一种能测量温度、气压和微温脉动的仪器。在天文圆顶附近,望远镜前方光路上,放置几组微温传感器,可以测得圆顶附近影响天文观测的湍流强度的分布情况。介绍了这套仪器的基本原理,电路设计,程序设计,实验定标以及一个简单的测试。     

乡村旅游社区景观空间演化研究

乡村旅游社区景观空间是在乡村旅游社区地域范围内,由于人类活动所产生的文化景观的总和。近年来,随着乡村旅游的快速发展,乡村旅游社区景观空间的演化受到人们的高度关注。本文将乡村旅游社区景观空间的演化置于演化经济地理研究框架内,认为其经历形成之前阶段、形成阶段、发展阶段和锁定或创新阶段四个阶段,每个阶段特征和演化机制各不相同。乡村旅游社区景观空间的演化是在遗传机制、变异机制等内因和选择机制、起点状态、关键事件等外因共同作用下,随着产业变迁而发生的具有路径依赖特征的演化过程。     

梅雨锋云系的模态研究Ⅱ：出现频率及转换特点

基于经验正交函数（EOF）分解方法提取的1998～2008年梅雨活跃期共16次过程的梅雨锋云系主导模态,讨论了这些主导模态的发生频率、维持时间及相互转换特征。结果表明,在16个梅雨活跃期内,云系的第1主导模态正相位出现的频率最高,并且在4个活跃期内作为首次出现模态率先出现;第5模态正位相的出现频率最低,且该模态多数伴随其他模态一同出现,为过渡模态。统计发现,各主导模态的维持时间并不相同,其中第2模态负位相持续时间最长,为81 h;第5模态正位相的最大持续时间最短,仅为18 h;第6模态负位相的平均持续时间最长。对不同主导模态转换方向和频次的计算表明,各个位相的模态最多（最少）向9种（3种）（含正负位相）其他模态进行转换。除第6模态负位相和第5模态负位相向其他模态的转化具有较好的方向性外,其他模态间的相互转换多表现出随机性特征。其中,第6模态负位相在超过半数的情况下向第5模态负位相转换,而第5模态负位相则多向第3模态正位相和第1模态负位相进行转换。     

1961-2010年辽宁省高温日数和高温热浪特征分析

利用1961-2010年辽宁省52个气象站日最高气温资料,分析辽宁地区高温日数及热浪的分布特征和变化趋势,结果表明：辽宁省区域年平均高温日数为7.72 d/ a。辽宁高温日数呈东少西多的空间分布,沿海地区较少甚至部分地区无高温情况出现。高温日出现最多的朝阳站,为26.48 d/ a。从20世纪60年代开始,高温日数呈缓慢增加趋势,其中2000年为有气象记录以来高温日最多的年份。热浪也呈东少西多的分布特征,热浪最多的朝阳站发生频次为2.90次/ a。辽宁省以持续3-5 d的轻度热浪为主,占86.27 %,中度热浪占12.58 %,超过10 d的重度热浪占1.14 %,仅有喀左、北票和羊山地区发生过持续10 d以上的重度热浪。     

Assessment of future runoff trends under multiple climate change scenarios in the Willamette River Basin,Oregon, USA

We investigated trends in future seasonal runoff components in the Willamette River Basin (WRB) of Oregon for the twenty‐first century. Statistically downscaled climate projections by Climate Impacts Group (CIG), eight different global climate model (GCM) simulations with two different greenhouse gas (GHG) emission scenarios, (A1B and B1), were used as inputs for the US Geological Survey's Precipitation Runoff Modelling System. Ensemble mean results show negative trends in spring (March, April and May) and summer (June, July and August) runoff and positive trends in fall (September, October and November) and winter (December, January and February) runoff for 2000–2099. This is a result of temperature controls on the snowpack and declining summer and increasing winter precipitation. With temperature increases throughout the basin, snow water equivalent (SWE) is projected to decline consistently for all seasons. The decreases in the centre of timing and 7‐day low flows and increases in the top 5% flow are caused by the earlier snowmelt in spring, decreases in summer runoff and increases in fall and winter runoff, respectively. Winter runoff changes are more pronounced in higher elevations than in low elevations in winter. Seasonal runoff trends are associated with the complex interactions of climatic and topographic variables. While SWE is the most important explanatory variable for spring and winter runoff trends, precipitation has the strongest influence on fall runoff. Spatial error regression models that incorporate spatial dependence better explain the variations of runoff trends than ordinary least‐squares (OLS) multiple regression models. Our results show that long‐term trends of water balance components in the WRB could be highly affected by anthropogenic climate change, but the direction and magnitude of such changes are highly dependent on the interactions between climate change and land surface hydrology. This suggests a need for spatially explicit adaptive water resource management within the WRB under climate change. Copyright © 2010 John Wiley & Sons, Ltd.     

铷原子频标中微波功率频移的研究及其控制方法

针对铷原子频标中微波功率频移的传统解释与实验现象不相符合的矛盾，曾提出以ＡＣＺｅｅｍａｎ效应为核心的新解释．本文以实验检验了该解释，尤其是ＡＣＺｅｅｍａｎ效应频移公式的正确性，实验结果与理论相符合；最后探讨了控制微波功率频移的方法。