浅谈感应雷检测

通过对避雷器技术参数的分析，结合实际检测工作，对感应雷的检测的主要内容，如漏电流、避雷器安装工艺以及接地系统等项目可能存在的雷击安全隐患提出了分析意见，并为感应雷防护工程设计因素和避雷器的选型及安装提出了一定的建议，从而达到以检测促进感应雷防护工程的设计水平及保护效果有质的提高。     

浅谈感应雷检测

通过对避雷器技术参数的分析,结合实际检测工作,对感应雷的检测的主要内容,如漏电流、避雷器安装工艺以及接地系统等项目可能存在的雷击安全隐患提出了分析意见,并为感应雷防护工程设计因素和避雷器的选型及安装提出了一定的建议,从而达到以检测促进感应雷防护工程的设计水平及保护效果有质的提高。     

Muddy lateral accretion and low stream power in a sub-recent confined channel belt, Rhine-Meuse delta, central Netherlands

The Hennisdijk fluvial system in the central Rhine-Meuse delta is an abandoned Rhine distributary that was active on a wide floodplain from 3800 to 3000 years BP . Cross-sectional geometry, lithological characteristics and planform patterns of the channel-belt deposits indicate lateral migration of the Hennisdijk palaeochannel. Channel-belt deposits are around 10 m thick and 200–400 m wide. A gravelly facies near the base of the channel-belt deposits represents channel-lag and lower point-bar deposits. The axis of the channel belt is dominated by a sandy facies (medium and coarse sand), showing an overall fining upward trend with multiple cycles. This facies is interpreted as lower and middle point-bar deposits. The sandy facies is capped by a muddy facies, which is 1–2 m thick near the axis of the channel belt and thickens to 5–6 m along the margins. It laterally interfingers with the sandy facies that occurs near the channel-belt axis, but it has sharp, erosive outer contacts marking the edges of the channel belt. The muddy facies comprises inclined heterolithic stratification (IHS) (fine/medium sand–mud couplets) in its upper part. The relatively thin muddy facies with IHS that occurs near the channel-belt axis is interpreted as upper point-bar deposits with lateral accretion surfaces, formed under marine influence. Along the margins of the channel belt the muddy facies consists of thick, fairly homogeneous, successions of mud with variable sand content, and fine sand. Based on facies geometry and position, this part of the muddy facies is interpreted as counterpoint deposits, formed along the upstream limb of the concave bank of a channel bend. Counterpoint accretion seems to have been associated with the confined nature of the channel belt, which was the result of low stream power (4·5–7·8 W m⁻², based on reconstructions of palaeodischarge and channel slope) and cohesive bank material, i.e. clayey floodbasin deposits with intercalated peat beds occurring next to the channel belt. In the literature, counterpoint accretion is mostly reported from alluvial valleys, where meandering is confined by limited floodplain width, whereas muddy lateral accretion surfaces are commonly reported from much wider marine-influenced floodplains. The present study shows juxtaposition of both forms of muddy channel deposits in a low-energy, wide coastal plain setting, where preservation potential is considerable.     

Critical specific stream power in gravel-bed rivers

Experiments with marked pebbles were carried out on different sized rivers of the Belgian Ardenne (catchment areas varying from less than 1 km² to 2700 km²). Specific stream power required to cause bedload movement was evaluated and critical values were obtained. Three types of relationship between critical specific stream power (ω₀) and grain size (D) were established. The values for ω₀ in the largest river (the Ourthe) were the lowest and were close to the values obtained for mountainous rivers carrying large boulders. In medium sized rivers (catchment area between 40 and 500 km²), the critical unit stream power was higher. It is likely that it is due to the bedform's greater resistance. This resistance would use up some of the energy that can cause movement and transport of bedload. The amount of resistance of the bedform can be expressed as bedform shear stress (τ″), determined by the relationship between grain shear stress (τ′—that determines movement and transport of the bedload) and the total shear stress (τ). This ratio varies between 0.4 and 0.5 in the medium sized rivers, compared to 0.7 in the Ourthe. In headwater streams (less than 20 km²), there is greater loss of energy due to bedform resistance (τ′/τ<0.3). Critical specific stream power is higher in this third type of river than in the other two.     

The form and function of headwater streams based on field and modeling investigations in the southern Appalachian Mountains

Headwater streams drain the majority of most landscapes, yet less is known about their morphology and sediment transport processes than for lowland rivers. We have studied headwater channel form, discharge and erosive power in the humid, moderate‐relief Valley and Ridge and Blue Ridge provinces of the Appalachian Mountains. Field observations from nine headwater (<2 km² drainage area), mixed bedrock–alluvial channels in a variety of boundary conditions demonstrate variation with respect to slope‐area channel initiation, basic morphology, slope distribution, hydraulic geometry, substrate grain size and role of woody debris. These channels display only some of the typical downstream trends expected of larger, lowland rivers. Variations are controlled mainly by differences in bedrock resistance, from the formation level down to short‐wavelength, outcrop‐scale variations. Hydrologic modeling on these ungauged channels estimates the recurrence of channel‐filling discharge and its ability to erode the channel bed. Two‐year recurrence discharge is generally larger and closer to bankfull height in the Valley and Ridge, due to low soil infiltration capacity. Discharge that fills the channel to its surveyed bankfull form is variable, generally exceeding two‐year flows at small drainage areas (<0·5 km²) and being exceeded by them at greater drainage areas. This suggests bankfull is not controlled by the same recurrence storm throughout a channel or physiographic region. Stream power and relative competence are also variable. These heterogeneities contrast relations observed in larger streams and illustrate the sensitivity of headwater channels to local knickpoints of resistant bedrock and armoring of channels by influx of coarse debris from hillslopes. The general lack of predictable trends or functional relationships among hydraulic variables and the close coupling of channel form and function with local boundary conditions indicate that headwater streams pose a significant challenge to landscape evolution modeling. Copyright © 2005 John Wiley & Sons, Ltd.     

大兴安岭北部森林沼泽区1∶5万水系沉积物测量方法研究

通过对在大兴安岭北部森林沼泽—冻土景观区的1∶5万水系沉积物测量方法技术的研究,发现以水系沉积物中较粗粒级的碎屑(-10～+60目)作为采样介质,可有效地排除有机质的干扰,强化异常;并提出在水系沉积物不甚发育的地区,以水系沉积物为主,辅以网格法土壤测量,则能更有效地提高找矿效果。     

MAPGIS技术在1：5万水系沉积物测量中的应用

传统的地球化学测量提交的成果，图件与分析数据表是分离的，综合异常专题图是感官上的色块表达，而在GIS中，地球化学专题资料既可以是利用区图元实体表达的综合异常专题图，也可以是原始分析数据或网格化数据，不仅可以输出需要的图形，还可以进行信息检索，统计和空间分析，将地球化学测量的采样点信息建成Microsoft Excel数据表，与点位空间图形链接，形成GIS数据，以全区和各类地层为统计单元，统计Au含量平均值，均方差，变化系数，分布的样品数量以及可按Au含量对数0.1为间隔的分组频数；据此建立DTM模型，可分析金异常分布特征，实现1：5万水系沉积物测量图形和数据库的微机化制作。     

大兴安岭北部森林沼泽区1:5万水系沉积物测量方法研究

通过对在大兴安岭北部森林沼泽—冻土景观区的1:5万水系沉积物测量方法技术的研究,发现以水系沉积物中较粗粒级的碎屑(-10～+60目)作为采样介质,可有效地排除有机质的干扰,强化异常;并提出在水系沉积物不甚发育的地区,以水系沉积物为主,辅以网格法土壤测量,则能更有效地提高找矿效果。     

首都圈遥测台网卫星传输台站数据流与传递函数

介绍了首都圈32个卫星台站的概况和数据传输的实现方法，阐述了数据采集器参数设定的有关问题，同时给出了不同类型地震仪测震观测技术指标。从原理上探讨了地震仪观测灵敏度和传递函数的测定方法，并对32个卫星传输台站传递函数的测定结果进行了分析。     

沉积体系分析与河道砂岩型铀矿成矿条件讨论--以鄂尔多斯中新生代盆地东胜地区为例

本运用沉积体系理论，对东胜地区直罗组的沉积相及沉积体系归属进行系统分析，指出直罗组为河流相沉积，其河流演化经历了早期辫状河、中期低弯度曲流河和晚期高弯度曲流河3个阶段。根据气候演变特点将直罗组分为上、下两个岩性段：下段为温湿条件下的辫状河沉积和低弯度曲流河沉积，形成灰色沉积建造；上段为干旱炎热条件下的曲流河沉积，形成以红色为主的杂色沉积建造。本区铀矿化属河道砂岩型，矿化受辫状河道控制，主要赋存于辫状河沉积砂体中。同时，对河道砂岩型铀矿化的成矿条件进行了初步探讨。