Working rivers: the geomorphological legacy of English freshwater mills

Freshwater mills historically were found throughout England serving a wide variety of uses. The decline in the need for water power over the last 100 years saw a reduction in the number of operational mills. Despite this decline, the associated river structures were rarely removed and many of these have exceeded their design life and have failed or are now starting to fail, with important geomorphological implications for the river. This paper investigates the geomorphological impacts of mills and their structures on English rivers, and considers their legacy for the contemporary management of these systems.     

溶胶-凝胶法制备纳米氧化镁研究

以硝酸镁和硬脂酸为原料,用溶胶—凝胶(Sol-Gel)法制备得到了纳米氧化镁微粒,并用热重(TG)分析、X-射线粉末衍射(XRD)、红外光谱(IR)和透射电镜(TEM)等对该纳米微粒的结构与形貌进行了表征。结果表明,控制Mg(NO3)2和CH3(CH2)16COOH物质的量比为1∶4,在90℃反应20 min并于360℃热处理4 h,得到立方相氧化镁纳米微粒,形貌为椭球体,分散性好,平均粒径约为33 nm。     

测绘市场的有序管理和执法要求

测绘市场的依法管理，是促进测绘事业健康发展的重要工作，因此要充分分析测绘工作的基本特征和发展趋势，使测绘市场管理走向规范、服务和促进测绘事业发展的正常轨道。     

2003年山西沙尘天气气候特征初步分析

本文通过1970年至2000年山西省扬沙和沙尘暴发生日数的统计分析，总结出山西省沙尘天气的时空特征，并对比近几年沙尘天气的情况，从环流特征和气候背景人手，分析2003年沙尘天气偏少的原因。     

AGEOSTROPHIC THEORY OF ZONAL FLOW ACCELERATION AND WAVE-ACTIVITY CONSERVATION LAW

Motivated by ageostrophic interactions of wave and basic flow,the generalized relationships between 3-dimensional Eliassen-Palm flux and basic flows,which are suitable for small-amplitude and finite-amplitude disturbances,are derived.The local area-averaged and density-weighted mean flows are chosen as the basic flows.Under the assumption that the steady basic flows vary slowly in time and space,a quasi-conservative law of small amplitude wave activity is derived from Ertel's potential vorticity equation in isentropic coordinates. The expressions of the new 3-D Eliassen-Palm flux and wave activity are presented in terms of Eulerian quantities so that they can be readily calculated by using observation data or model output data.     

盘锦台高七井地热映震规律探讨

总结了盘锦台高七井地热测项的异常特征和映震规律，同时对1999年11月29日岫岩Ms5．4级地震后高七井地热的趋势转向问题进行了讨论。     

Mythos and techne: An essay on the intercultural function of territory in sub-Saharan geography

Territorial symbolism in sub-Saharan Africa calls to mind multiple forms of knowledge. More particularly, territorial significance is fed both by magical and sacred beliefs and by knowledge based on empirical observation and concrete practices. These two types of knowledge differ widely as to their nature, the procedures by which they are formed, and the cultural values they embody. Nevertheless, semantic interaction between mythical knowledge and technical knowledge is remarkably rich. By blurring the distinction between mythos and techne, this semantic interaction seems to constitute an important cultural tool for building feelings of social security in that it reinforces and stabilizes socio-geographic patterns, and more especially those which regulate access to space and natural resources. This revised version was published online in July 2006 with corrections to the Cover Date.     

Sonic anemometers in aeolian sediment transport research

Fast-response wind and turbulence instruments, including sonic anemometers, are used more and more in aeolian sediment transport research. These instruments give information on mean wind, but also on fluctuations and turbulent statistics, such as the uw covariance, which is a direct measure of Reynolds' stress (RS) and friction velocity. This paper discusses the interpretation of sonic anemometer data, the transformations needed to get proper results and turbulence spectra, and how they are influenced by instrument size, sampling frequency, and measurement height.Turbulence spectra characterize how much the different frequencies in the turbulent signals contribute to the variance of wind speed, or to the covariance of horizontal and vertical wind speed. They are important in determining the measurement strategy when working with fast-response instruments, such as sonic anemometers, and are useful for interpreting the measurement results. Choices on the type of sonic anemometer, observation height, sampling period, sampling frequency, and filtering can be made on the basis of expected high and low-frequency losses in turbulent signals, which are affected by those variables, as well as wind speed and atmospheric stability.Friction velocity and RS, important variables in aeolian sediment transport research, are very sensitive to tilt or slope errors. During a field experiment, the slope sensitivity of the RS was established as 9% per degree of slope, which is 1.5 times the value reported in literature on the basis of theoretical considerations. An important reason for the difference probably is the large influence of streamline curvature on turbulence statistics and thereby on the slope sensitivity of the RS. An error of 9% per degree of slope in the RS will translate into an error of approximately 4% per degree of slope in the calculated friction velocity.Space–time correlation of the horizontal wind speed is much larger than that of the vertical wind speed and the instantaneous RS. This largely explains why, in previous studies, a poor correlation was found between instantaneous RS measured at 3 m height and saltation flux near the surface, whereas the correlation between wind speed at some height and saltation flux was much better. Therefore, the poor correlation between RS away from the surface and saltation flux does not contradict that saltation flux is caused by RS.     

Assessment of downstream trends in channel gradient, total and specific stream power: a GIS approach

Geographic Information Systems (GIS) analyses of Digital Elevation Models (DEMs) coupled with catchment area based discharge estimation techniques provide a relatively simple means of modelling contiguous downstream trends in channel gradient, total stream power, and in riverscapes conducive to regime analysis, also specific stream power. For a small, high relief, coastal catchment in SE Australia, good agreement was obtained between channel gradients derived from a 25 m cell-size DEM and field survey equivalents over distances of several kilometres, indicating that channel gradients derived from DEMs can have a reasonable degree of absolute as well as relative accuracy over multi-kilometre reach scales. Assessment of downstream rates of change in channel gradient and specific stream power across four river systems suggests that some of the river reaches most responsive to high magnitude floods occur in zones where these variables rapidly decrease downstream. Modelling of downstream trends in channel gradient, total and specific stream power from catchment-wide DEMs has potential to provide a framework with which to investigate conceptual and empirical models between channel gradient, stream power and the form and dynamics of river systems.     

山西数字遥测地震台网各子台台址地脉动噪声分析

通过对山西数字遥测地震台网11个子台台址背景噪声进行分析和计算，得出了各台址背景噪声地脉动速度均方根值(RMS值)、观测动态范围、噪声信号功率谱。结果表明各台址背景噪声水平基本符合数字地震观测技术规范要求。