CFL 03型风廓线雷达自动标校方法研究

风廓线雷达已经广泛应用于国民经济的许多领域,现在对于其应用已不仅仅局限于风场资料,对回波强度、信噪比、速度谱宽等信息的使用也越来越多。因此,对其开展标校工作就显得非常重要。以CFL-03型风廓线雷达为例,介绍了一种风廓线雷达的自动标校技术,从技术方案设计到信号流程、系统硬件组成,以及对其实现方法进行了研究,并用机外仪器对设备进行了测试,将测试结果和自动标校结果进行了对比,对比结果证明该自动标校系统的精度达到了设计目的,能够满足雷达业务运行要求。     

Large wood retention in river channels: the case of the Fiume Tagliamento,Italy

After more than 300 years of widespread and intensive river management, few examples of complex, unmanaged river systems remain within Europe. An exception is the Fiume Tagliamento, Italy, which retains a riparian woodland margin and unconfined river channel system throughout almost the entire 170 km length of its river corridor. A research programme is underway focusing on a range of related aspects of the hydrology, fluvial geomorphology and ecology of the Tagliamento. This paper contributes to that programme by focusing on large wood retention. The paper adopts a simple force:resistance approach at the scale of the entire river corridor in order to identify reaches of the river with a high wood retention potential. Information on the character of the river corridor is derived from 1:10 000 scale topographic maps. A range of indices measured at 330 transects across the river corridor supports a classification of the geomorphological style of the river which reflects the presence and abundance of properties previously identified in the literature as large wood retention sites. This classification provides a qualitative representation of the ‘resistance’ of the corridor to wood movement and thus its overall wood‐retention potential. The map‐derived indices are also used to extrapolate estimates of the ten year return period flood to each of the 330 transects so that the downstream pattern of unit stream power can be quantified as an index representing ‘force’ in the analysis. Although input of wood is an important factor in many river systems, it is assumed not to be a limiting factor along the Tagliamento, where riparian woodland is abundant. Field observations of large wood storage illustrate that wood retention at eight sites along the river reflects the presence and abundance of the features incorporated in the classification of geomorphological style, including the complexity of the channel network, the availability of exposed gravel areas, and the presence of islands. In general at the time of survey in August 1998, open gravel areas were estimated to store approximately 1 t ha⁻¹ of wood in single‐thread reaches and 6 t ha⁻¹ in multiple‐thread reaches. Established islands were estimated to store an average of 80 t ha⁻¹ of wood. Nevertheless, there was considerable variability between sites, and pioneer islands, which are not represented on maps or readily identified from air photographs because of their small size, were estimated to store an order of magnitude more wood than established islands. Furthermore, the wood storage from this sample of eight sites did not reflect variability in estimated unit stream power. A series of areas for further research are identified, which can be explored using field data, and which will throw more light on the processes of wood retention in this extremely dynamic fluvial environment. Copyright © 2000 John Wiley & Sons, Ltd.     

大功率激电在铅锌矿勘查中的应用--以辽宁省岫岩县王家堡子铅锌多金属矿为例

辽宁省岫岩县王家堡子铅锌多金属矿位于青城子-许屯铅锌矿带上,通过大功率激电测量查明工作区激电异常特征,综合地质、化探信息,笔者认为矿区侵入岩区带状极化率异常是铅锌矿的找矿标志,沉积岩中石墨矿化引起区域性高极化,根据激电剖面异常特征有利于区分矿与非矿。     

Power law or power flaw?

Since its introduction by Svensson in 1959, the power law curve y = ax^b (where x and y are horizontal and vertical direction, respectively) has been widely used in morphological analysis of glacial trough cross-profiles. The numerical constants a and b are obtained by a linear regression analysis of the logarithmic form of the power law curve (ln y = ln a + b ln x). The value b then gives a measure for the form of the cross-section. However, over the years this form of the power law has endured a lot of criticism. This criticism is well founded, since this particular form of the power law is not suitable for curve fitting in morphological analyses. In this paper a general power law is proposed, of the form y − y₀ = a|x − x₀|^b (where x₀, y₀ are the coordinates of the origin of the cross-profile). A unique and unbiased solution for this equation is obtained with a general least-squares method, thereby minimizing the error between the cross-profile data and the curve, and not between the logarithmic transform of the data and its regression line. This provides a robust way to characterize trough cross-section forms. © 1998 John Wiley & Sons, Ltd.     

Evaluating impacts of pulse fishing on the effectiveness of seasonal closure

Seasonal fishing closures are often used in fisheries management to conserve overfished stocks.As one of the unintended consequences,fishermen often contend for maximizing catches immediately after reopening fisheries.The resultant large catch landings in a short time period(i.e.,pulse fishing)may undermine the benefit of closure.We implemented an end-to-end model OSMOSE-JZB(Object-oriented Simulator of Marine ec OSystem Exploitation OSMOSE)modelling ecosystem in the Jiaozhou Bay located in China to evaluate the impact of pulse fishing on the effectiveness of seasonal closure at levels of fish community,population,and individual.Our study demonstrated that the three-month closure was successful in conserving fish stocks.There were small variations on ecological indicators(i.e.,total biomass of the community,mean trophic level of the community,mean trophic level of the catch,and Shannon-Wiener biodiversity index)when pulse fishing occurred.Pulse fishing seemed not to result in a great shift in community structure.Compared to other species,the biomass of two large predatory fishes were more susceptible to pulse fishing.Pulse fishing could change the pressure of predators to fish stocks via food webs,especially for young individuals.Our simulations indicate that we can improve the effectiveness of seasonal closure by managing pulse fishing.Although the results derived in this study may be specific to the target ecosystem,the general approach is applicable to other ecosystems when evaluating fishing impacts.     

一种基于滨海核电站海上γ辐射剂量率的智能化自动监测系统研究与设计

基于滨海核电站海上γ辐射剂量率的智能化自动监测系统是一种无人值守的辐射监测装备,可全天候、长时间、在线组网、连续自动测量水面和空气中的γ剂量率、获取水中γ能谱数据并进行核素识别和计算活度浓度,并实时地将监测数据通过无线通信链路和北斗短报文两种形式上传至地面数据服务中心。在非事故情况下,该系统是对核电厂监督性监测系统的重要补充和完善;在发生重大核安全事故或放射性物质泄漏的情况下,能够有效解决传统的派船巡测时方法不标准、数据不及时不连续、人员受照风险大、船只易受污染和行动代价高等问题;在恶劣的极端气象条件下,无人值守的自动监测系统能够为核电站提供实时有效的水体和空气中的γ剂量率、气象、海水温度等监测数据,有效地提升了核电站在极端气象条件下的监测能力,对滨海核电站整体的安全性和可靠性具有一定积极意义。     

Savonius型桨叶水动力特性研究

Savonius桨叶是一种典型的垂直轴阻力型桨叶,在风力发电中广泛应用。这种桨叶具有在多风向作用下单向转动的特性。利用该特性,将其应用于捕获水质点运动方向发生周期性或非周期性改变的波浪能的相关研究。采用Fluent数值仿真软件并基于UDF二次开发技术建立桨叶三维数值模型,分析叶片重叠率、相对入水深度和开口率等参数对桨叶动转矩和功率等水动力特性的影响,搭建实验平台,开展物理模型对照试验。研究结果表明:叶片重叠率有助于减小S型桨叶负转矩;当桨叶在水面上高度与波幅相等时,其功率系数达到最大;在叶片上增加弹片阀开口,可以增大桨叶动转矩系数,当开口面积达到一半时,动转矩系数比未开口桨叶提高28.3%。     

海上风机吸力基础的水平受荷研究综述

吸力基础具有施工速度快、安装过程中受海况天气影响小且易于回收重复利用等优点,被广泛应用于海洋工程。当吸力基础作为海上风电塔架的基础时,常常承受较大的水平荷载,因此其水平承载力是设计的主控因素。介绍了海上风机基础的设计要求,分析了影响基础水平承载性状的因素,总结了吸力基础受水平单调荷载、水平循环荷载和不同荷载组合三个方面的研究现状。讨论了水平荷载的大小、水平加载的高度(偏心率)、循环荷载的频率、循环荷载的次数、循环荷载的幅值、循环荷载的方向性、竖向荷载对吸力基础水平承载性状的影响,考虑了水平荷载的非共线性,指出了目前研究的不足,明确了吸力基础水平承载性状进一步研究的方向,提出了供工程实践参考的建议。     

基于功率变化的移动终端欺骗干扰检测方法

对欺骗信号的功率检测是目前最常用的欺骗检测方法之一,但欺骗源可以通过调整发射的信号功率,仍然可实现对环形范围内所有终端的欺骗攻击．针对该问题,本文提出了一种基于信号功率变化的移动终端欺骗干扰检测方法,该方法利用了真实卫星和欺骗源与终端在距离上差异的本质属性,通过终端运动情况下真实信号与欺骗信号在相同距离上信号功率变化的不同,实现对近距离欺骗干扰源的有效检测．本文建立了移动终端导航信号功率变化模型,并在此基础上给出了针对欺骗信号的二元假设检验方法．通过理论分析和仿真实验,验证了本文提出的基于信号功率变化的移动终端欺骗干扰检测技术的有效性,当干扰源距离终端小于2 000 m,终端运动距离大于200 m即可实现在1％的虚警概率下实现对97％以上欺骗攻击的有效检测．