如何打造一个神奇的微型Linux OS     

李代伟  张钟澍  蔡淮  何嘉 《成都信息工程学院学报》2003,18(2):119-124

描述如何设计与打造自己的LinuxBoot＆Root磁盘。这些磁盘能用来当作应急盘、测试新的系统组件、路由器、代理服务器、进行操作系统教学;或是用作小工具,可以用它上网、读新闻、看信和浏览等;还可以用于嵌入式系统。该系统的Boot＆Root的容量总共不到5M,压缩后的Root可放于一张或两张软盘上;它还可以轻松运行于任一裸机上。  相似文献   

Linux嵌入式系统根文件系统的选择与制作     

冯世奎  刘玓 《成都信息工程学院学报》2006,21(4):508-512

Linux操作系统做为嵌入式系统近年应用越来越广泛，Linux根文件系的装载是Linux内核启动期间进行的最后操作之一，它是Linux嵌入式系统的一个重要组成部分，系统地分析了Linux嵌入式系统根文件系统的类型，内容选择以及制作方法。  相似文献   

航空摄影测量应用中平坦地区高程精度的探索与实践     

孟庆辉  李玉兰 《安徽地质》2007,17(3):230-232,240

高程精度低的问题,一直是航空摄影测量产品的弱点,因此也是生产设计中的技术要点,本文通过三个实例,对不同资料、不同比例尺成果要求,采用不同技术措施保证了成果高程精度的做法进行了总结.  相似文献   

多波束测深系统时延偏差探测及校正方法     

张志伟  暴景阳  肖付民  上飞飞 《测绘科学技术学报》2015,(6):574-577

在利用多波束测深系统进行高精度海底地形测量时,各传感器之间数据采集时间不同步的问题,即存在时延偏差,这将会直接影响多波束测深数据质量,为此提出了一种基于最小二乘原理的多波束测深时延偏差探测及校正方法,给出了时延偏差探测及校正计算模型,设计了时延偏差探测及校正流程,通过实例分析,验证了所提方法的适用性和有效性。  相似文献   

Effect of vegetation cover and sediment type on 3D subsurface structure and shear strength in saltmarshes     

Clementine Chirol  Kate L. Spencer  Simon J. Carr  Iris Möller  Ben Evans  Jason Lynch  Helen Brooks  Katherine R. Royse 《地球表面变化过程与地形》2021,46(11):2279-2297

The vulnerability of saltmarshes to lateral erosion at their margin depends on the local biogeomorphological properties of the substrate. In particular, the 3D architecture of pore and root systems is expected to influence shear strength, with repercussions for the wider-scale stability of saltmarshes. We apply X-ray computed microtomography (μCT) to visualize and quantify subsurface structures in two UK saltmarshes at Tillingham Farm, Essex (silt/clay rich substrate) and Warton Sands (sand-rich substrate), with four types of ground cover: bare ground, Spartina spp, Salicornia spp and Puccinellia spp. We extracted μCT structural parameters that characterize pore and root morphologies at each station, and compared them with field measurements of shear strength using a principal component analysis and correlation tests. The 3D volumes show that species-dependent variations in root structures, plant colonization events and bioturbation activity control the morphology of macropores, while sediment cohesivity determines the structural stability and persistence of these pore structures over time, even after the vegetation has died. Areas of high porosity and high mean pore thickness were correlated to lower values of shear strength, especially at Tillingham Farm, where well-connected vertical systems of macropores were associated with current or previous colonization by Spartina spp. However, while well-connected systems of macropores may lower the local deformation threshold of the sediment, they also encourage drainage, promote vegetation growth and reduce the marsh vulnerability to hydrodynamic forces. The highest values of shear strength at both sites were found under Puccinellia spp, and were associated with a high density of mesh-like root structures that bind the sediment and resist deformation. Future studies of marsh stability should ideally consider time series of vegetation cover, especially in silt/clay-dominated saltmarshes, in order to consider the potential effect of preserved buried networks of macropores on water circulation, marsh functioning and cliff-face erosion.  相似文献   

Pseudo-hysteretic double-front hiatus-stage soil water parcels supplying a plant–root continuum: the Green-Ampt-Youngs model revisited     

Anvar Kacimov 《水文科学杂志》2013,58(1):237-248

Abstract

A tension-saturated water slug descends through a homogenous soil after a rainfall (irrigation) event and shrinks due to transpiration by a distributed root-sink and evaporation. The upper (drainage) and lower (imbibition) sharp fronts of the slug separate it from the superjacent and subjacent vadose zones, where water is immobile. In the slug, the hydraulic conductivity is constant according to the Green-Ampt model. The capillary pressures as well as effective porosities on the fronts are given (generally, different) constants that can be viewed as a kind of hysteresis. A volumetric sink models mild (no desaturation of the slug) soil water withdrawal by the plant roots. The sink intensity varies with the depth from the soil surface and with time. Mathematically, the hydraulic head is immediately expressed by double integration of a governing 1-D flow equation. The pressure and kinematic conditions on the fronts result in a Cauchy problem for a system of two ODEs, which is solved by computer algebra routines.

Editor D. Koutsoyiannis

Citation Kacimov, A. and Obnosov, U., 2013. Pseudo-hysteretic double-front hiatus-stage soil water parcels supplying a plant–root continuum: the Green-Ampt-Youngs model revisited. Hydrological Sciences Journal, 58 (1), 1–12.  相似文献   

Characterizing errors in digital elevation models and estimating the financial costs of accuracy     

S. R. Januchowski  R. L. Pressey  J. VanDerWal  A. Edwards 《International journal of geographical information science》2013,27(9):1327-1347

Digital topographic models are the foundation of more advanced modeling applications and ultimately inform planning and decision making in many fields. Despite this, the error associated with these models and derived attributes is commonly overlooked. Little attention has been given in the scientific literature to the benefits gained from having less error in a model or to the corresponding cost associated with reducing model error by choosing one product over another. To address these gaps in knowledge we evaluated the error associated with five digital elevation models (DEMs) and derived attributes of slope and aspect relative to the same attributes derived from LiDAR data. We also estimated the acquisition and processing costs per square kilometer of the five test models and the LiDAR models. We used three measures to characterize model error: (1) root mean square error, (2) mean error (and standard deviation), and (3) area of significant elevation error. We applied these measures to DEM products that are used extensively across a range of applications for planning and managing natural resources. We depicted the relationship between model accuracy (the inverse of error) and cost in two ways. One was accuracy/cost ratio for each model. The other used separate data on accuracy and cost to better guide potential users in choosing between models or deciding on necessary expenditure on models. The main conclusion of our work was that accounting for error in DEMs can inform choice of models and the need for financial outlays.  相似文献   

江西省鄱阳湖流域根系土硒形态分析及其迁移富集规律   总被引：5，自引：0，他引：5  

魏然  侯青叶  杨忠芳  尹国胜  衷存堤  邓国辉  马逸麟 《物探与化探》2012,(1):109-113

对江西省鄱阳湖流域根系土中硒的形态分析表明,根系土中Se的强有机态、腐植酸结合态约占Se全量的66.23%,残渣态占12.32%,3种形态均与根系土Se全量呈极显著的线性正相关。根系土Se全量受pH值的影响不明显,但受有机质含量的影响很大,线性回归关系极显著,说明岩石风化、土壤发育过程中,有机质吸附Se,致使Se较其他元素流失比例少,造成根系土中Se相对富集。同时,提出了利用全量Se推导Se各形态值的方法,建立了土壤Se全量与各形态间的关系模型和决定土壤有效态Se的公式,建议在评价土壤Se时只用考虑有机结合态Se、残渣态Se、水溶态Se和全量Se。  相似文献   

极度干旱区不同灌水量下沙枣防护林根系分布特征   总被引：1，自引：0，他引：1  

赵新风  徐海量  刘新华  张鹏  刘志友  洪辉 《地理科学进展》2012,31(5):646-654

研究滴灌条件下极端干旱区防护林的根系生长, 对研究制定科学的防护林灌溉制度和维护绿洲防护林稳定性有重要意义。以塔里木河下游尾闾绿洲--喀拉米吉绿洲滴灌沙枣防护林体系为研究对象, 设置了3 个滴灌量梯度(18 L、30 L、48 L), 分析了极端干旱区沙枣防护林在不同灌水量处理下的根系分布特征。结果表明:①长期采用滴灌后, 沙枣根系大部分分布在较浅的土层(以地下0～40 cm为主), 越往下分枝能力越小, 沙枣根系生物量在0～60 cm土层中累计百分比达86%。②灌水量梯度不断增加后, 导致了根系总生物量随之增加, 但不会导致深层土壤根系持续增加, 因此, 即使用48 L的灌水量形成更深的土壤湿润层, 林木根系下扎能力与深度没有表现出随之增加的趋势。48 L滴灌量处理下, 土层根系含量20～40cm/0～20cm的比值较小(仅为0.6), 生物量主要集中在表层;30 L处理下, 土层根系含量20～40cm/0～20cm的比值较大(0.75)。③粗根(φ≥5 mm)数量随着滴灌量的增大而增多, 30 L滴灌量处理下, 5 mm>φ>2 mm的根最多;18 L滴灌量处理下, φ≥5 mm的根与φ≤2 mm的根系数量均最少。建议大规模防护林的灌溉中应采取多样化的灌溉制度, 才可达到极端干旱区防护林体系的可持续发展:棉林争水季节(5-7 月)适当亏缺灌溉, 8月以后可增加灌水量或1～2 次灌水。  相似文献   

Evaluation and fusion of SST data from MTSAT and TMI in East China Sea, Yellow Sea and Bohai Sea in 2008   总被引：1，自引：0，他引：1  

伍玉梅  申辉  崔雪森  杨胜龙  樊伟 《中国海洋湖沼学报》2012,30(4):697-702

Two typical satellite sea surface temperature (SST) datasets, from the Multi-functional Transport Satellite (MTSAT) and Tropical Rainfall Measuring Mission Microwave Imager (TMI), were evaluated for the East China Sea, Yellow Sea, and Bohai Sea throughout 2008. Most monthly-mean availabilities of MTSAT are higher than those of TMI, whereas the seasonal variation of the latter is less than that of the former. The analysis on the one-year data shows that the annual mean availability of MTSAT (61%) is greater than that of TMI (56%). This is mainly because MTSAT is a geostationary satellite, which achieves longer observation than the sun-synchronous TMI. The daily availability of TMI (28%-75%) is more constant than that of MTSAT (9%-93%). The signal of infrared sensors on MTSAT is easily disturbed on cloudy days. In contrast, the TMI microwave sensor can obtain information through clouds. Based on in-situ SSTs, the SST accuracy of TMI is superior to that of MTSAT. In 2008, the root mean square (RMS) error of TMI and MTSAT were 0.77 K and 0.84 K, respectively. The annual mean biases were 0.14 K (TMI) and -0.31 K (MTSAT). To attain a high availability of SSTs, we propose a fusion method to merge both SSTs. The annual mean availability of fusion SSTs increases 17% compared to MTSAT. In addition, the availabilities of the fusion SSTs become more constant. The annual mean RMS and bias of fusion SSTs (0.78 K and -0.06 K, respectively) are better than those of MTSAT (0.84 K and -0.31 K).  相似文献