盐度对三种荒漠植物渗透调节物质积累影响的研究

 以甘肃省河西走廊荒漠盐碱地生长的盐爪爪、罗布麻和苏枸杞为研究材料，测定了其在不同盐度下叶片几种渗透调节物质的含量和Na⁺、K⁺-ATPase活性。研究了3种荒漠植物对盐胁迫的生理响应及适应特征。研究结果表明，盐爪爪叶片的Na⁺/K⁺比和Na⁺+K⁺的总量均明显高于罗布麻和苏枸杞;土壤盐分增加，盐爪爪叶片的Na⁺、K⁺-ATPase活性增强，而罗布麻和苏枸杞叶片的Na⁺、K⁺-ATPase活性降低;盐爪爪可溶性糖分和脯氨酸的积累量均明显提高，而罗布麻和苏枸杞叶片可溶性糖分和脯氨酸的变化趋势不一致。可见盐爪爪对盐胁迫的耐受力和渗透调节力均强于罗布麻和苏枸杞。     

Merging multiple precipitation sources for flash flood forecasting

We investigated the effectiveness of combining gauge observations and satellite-derived precipitation on flood forecasting. Two data merging processes were proposed: the first one assumes that the individual precipitation measurement is non-bias, while the second process assumes that each precipitation source is biased and both weighting factor and bias parameters are to be calculated. Best weighting factors as well as the bias parameters were calculated by minimizing the error of hourly runoff prediction over Wu-Tu watershed in Taiwan. To simulate the hydrologic response from various sources of rainfall sequences, in our experiment, a recurrent neural network (RNN) model was used.

The results demonstrate that the merged method used in this study can efficiently combine the information from both rainfall sources to improve the accuracy of flood forecasting during typhoon periods. The contribution of satellite-based rainfall, being represented by the weighting factor, to the merging product, however, is highly related to the effectiveness of ground-based rainfall observation provided gauged. As the number of gauge observations in the basin is increased, the effectiveness of satellite-based observation to the merged rainfall is reduced. This is because the gauge measurements provide sufficient information for flood forecasting; as a result the improvements added on satellite-based rainfall are limited. This study provides a potential advantage for extending satellite-derived precipitation to those watersheds where gauge observations are limited.     

BOOK REVIEWS

Book Reviewed in this article: Rabat: Urban Apartheid in Morocco . Janet Abu -Lughod . Marketplaces in a Developing Country: The Case of Western Nigeria . Isaac Ayinde Adalemo . Farming Development and Space: A World Agricultural Geography . Bernd Andreae . Section and Party: A Political Geography of American Presidential Elections, from Andrew Jackson to Ronald Reagan . J. Clark Archer and Peter J. Taylor . Women and Space: Ground Rules and Social Maps . Shirley Ardener , ed. European Progress in Spatial Analysis . R. J. Bennett , ed. The Origins of Academic Geography in the United States . Brian W. Blouet Geographic Perspectives on Global Problems . Ronald Reed Boyce . Seasonal Dimensions to Rural Poverty . Robert Chambers , Richard Longhurst and Arnold Pacey eds. The New Nationalism and the Use of Common Spaces: Issues in Marine Pollution and the Exploitation of Antarctica . Jonathan I. Charney , ed. Communications Tomorrow: The Coming of the Information Society . Edward Cornish , ed. The Design of Suburbia . Arthur Edwards . Explorer on the Northern Plains: Lieutenant Gouverneur K. Warren's Preliminary Report of Explorations in Nebraska and Dakota in the Years 1855–56–57. With an Introduction by Frank N. Schubert . The Changing Climate: Responses of the Natural Flora and Fauna . Michael J. Ford . Essentials of Physical Geography . Robert E. Gabler , Robert J. Sager , Sheila Brazier , and Daniel L. Wise. The Road to Jaramillo . William Glen . Valued Environments . John R. Gold and Jacquelin Burgess , eds. Proximity and Preference: Problems in the Multidimensional Analysis of Large Data Sets . Reginald G. Golledge and John N. Rayner , eds. A Search for Common Ground . Peter Gould and Gunnar Olsson , eds. Geography: Its History and Concepts . Arild Holt -Jensen . A Population Geography . Huw R. Jones . The Human Mosaic: A Thematic Introduction to Cultural Geography, 3rd ed. Terry G. Jordan and Lester Rowntree . Urban Social Geography: An Introduction . Paul Knox . The Anatomy of Job Loss: The How, Why and Where of Employment Decline . Doreen Massey and Richard Meegan . The Information Society as Post-Industial Society . Yoneji Masuda . Map Librarianship, 2nd ed. Harold Nichols . India: Cultural Patterns and Processes . Allen G. Noble and Ashok K. Dutt , eds. The God that Limps: Science and Technology in the Eighties . Colin Norman . Geography: An Introductory Perspective . Robert E. Norris , Keith D. Harries and John D. Vitek . The Politics of Technology Assessment . David M. O'Brien and Donald A. Marchand . Ethnic Segregation in Cities . Ceri Peach , Vaughan Robinson and Susan Smith , eds. Churches and Church Membership in the United States, 1980 . Bernard Quinn , Herman Anderson , Martin Bradley , Paul Goetting and Peggy Shriver . Energy in Australia: Politics and Economics . Hugh Saddler . Development from Above or Below? The Dialectics of Regional Planning in Developing Countries . Walter B. Stóuhr and D. R. Fraser Taylor , eds. Human Impact on the Ecosystem . Joy Tivy and Greg O'Hare . Plants and People: Vegetation Change in North America . Thomas R. Vale . The Mapmakers: The Story of the Great Pioneers in Cartography from Antiquity to the Space Age . John Noble Wilford .     

浅谈空中三角测量在实际工作中的应用

提出了利用VirtuoZo AAT进行空中三角测量的工作流程,并通过在VirtuoZo数字摄影测量工作站上进行的实验,对自动空中三角测量的实际精度进行了分析,提出了实际应用的一些看法。     

ADS40推扫式数字航摄仪试验研究

ADS40是当今最先进的摄影测量系统之一,它采用推扫式三线阵获取影像,可以提供多种类型的数字影像数据。由于配备IMU/DGPS系统,在一定的基站范围内可以在无控制或少量控制点的情况下进行空三平差,极大地减轻了摄影测量外业控制工作量,缩短了生产周期,提高了作业效率。本文就ADS40的原理、数据处理流程,以及ADS40和常规摄影测量的区别,在精度等方面作了阐述和分析,并就其在我国摄影测量领域内的应用进行了展望。     

平差数学模型教学改革的探讨

在测量平差概述的教学过程中,通过对必要量、观测量、必要观测量、多余观测量、必要起算数据、多余起算数据等几个概念之间关系的分析,有助于学生理解与掌握平差数学模型的建立,教学效果较好。     

重力基点网平差中的间接平差

笔者将间接平差方法引入重力基点网平差中。将基点网中各个基点的重力平差值设为与其近似值有关的函数;利用最小二乘准则约束参数函数,建立误差方程;求出平差值。计算结果显示,传统条件平差以及间接平差方法的平差结果相同,但是间接平差的计算过程更有规律性,便于编程计算,适用于由多基点、多边段组成的复杂基点网。     

附加视线向量修正的卫星影像区域网平差

针对传统有理函数模型(RFM)区域网平差方法局限于姿态和轨道测量误差小、相机视场角小及影像交会角良好的情况,提出了附加视线向量修正的卫星影像区域网平差方法。首先利用影像附带的有理多项式系数(RPC)计算出像元视线向量,其次根据该视线向量恢复成像时刻虚拟位置和姿态信息,然后对恢复的虚拟位置和姿态构建误差补偿模型,最后通过最小二乘方法整体解算模型参数和连接点物方坐标。该方法从系统误差产生的原因构建补偿模型,可以规避传统区域网平差方法的近似假设和条件限制。通过对模拟数据以及多套测绘卫星和非测绘卫星数据进行试验的结果表明,该方法处理大姿态角误差、大视场角以及弱交会角等各种严苛条件下的卫星影像能达到比传统方法更好的效果。     

一种改进的水准网条件平差算法

在实际工程应用中,水准网网形复杂多样,当进行平差时,间接平差未知参数个数选取要求高,条件平差方程建立不唯一,针对此类问题,本文提出了一种利用传递数矩阵建立条件方程的算法,判断水准网中的水准路线和水准点是否是已知值,依据传递数矩阵运算规则,确定条件平差中的系数矩阵和常数项矩阵,并利用2个算例进行分析比较,证明了所提算法的有效性。