BOOK REVIEWS

Abstract

The Regional Geography of Canada, 3rd ed.Robert M. Bone Oxford University Press 70 Wynford Drive, Don Mills, ON, M3C 1J9, Canada 2005, xxi + 572 pp Hard Cover ($45.00 US) ISBN 0-19-541933-2     

Teaching Controversial Topics: Iconography and the Confederate Battle Flag in the South

Abstract

This article examines various strategies for teaching controversial topics. As a case study, I present examples from my experience teaching about the cultural/political geographic concept of iconography in southern classrooms using as an example recent debates over whether governments in the region should sanction the flying of the Confederate battle flag. First, I discuss the recent literature on the teaching of controversial issues. Second, I examine the concept of iconography and the debates over flying the flag. Third, I present different strategies that can be used to approach this controversial icon in a classroom setting. I conclude by arguing that there is no perfect solution to the teaching of controversial topics that will succeed for every topic, irrespective of time and place.     

A correlation for permanent earthquake-induced deformation of earth embankments

Seismic design of earth dams and embankments is mainly controlled by the permanent deformation that may be induced directly or indirectly because of the design earthquake. Simple design charts, such as those developed by Yegian et al. [Yegian, M.K., Marciano, E.A., and Ghahraman, V.G. 1991. Earthquake-induced permanent deformations: Probabilistic approach. J. Geotech. Eng., 117, 35–50.], Hynes-Griffin and Franklin [Hynes-Griffin, M.E., and Franklin, A.G. 1984. Rationalizing the Seismic Coefficient Method. Miscellaneous Paper GL-84-13, US Army Corps of Engineers Waterways Experiment Station, Vicksburg, Mississippi.], Makdisi and Seed [Makdisi, F.I., and Seed, H.B. 1978. Simplified procedure for estimating dam and embankment earthquake-induced deformations. J. Geotech. Eng., 104, 849–867.], and Sarma [Sarma, S.K. 1975. Seismic stability of earth dams and embankments. Géotechnique, 25, 743–761.], are often used to obtain a preliminary estimate of the permanent, earthquake-induced deformation of earth dams and embankments. Comparison of permanent deformations estimated from these procedures with observations from 122 published case histories on performance of earth dams and embankments during past earthquakes indicate that the estimated permanent earthquake-induced deformations were, in general, smaller than the observed deformations. However, the observed permanent deformation, D_avg, was found to relate to the ratio of yield acceleration, a_y, and the peak horizontal ground acceleration, a_max. The scatter in the observational data, upon which the D_avg–a_y/a_max relationship is based, can be partly explained by the variations in the ratio of the fundamental (elastic) period of the earth structure, T_D, and the predominant period of the earthquake ground motion, T_p, and the magnitude of the earthquake, M_W.     

Joint inversion of high-frequency surface waves with fundamental and higher modes

Joint inversion of multimode surface waves for estimating the shear (S)-wave velocity has received much attention in recent years. In this paper, we first analyze sensitivity of phase velocities of multimodes of surface waves for a six-layer earth model, and then we invert surface-wave dispersion curves of the theoretical model and a real-world example. Sensitivity analysis shows that fundamental mode data are more sensitive to the S-wave velocities of shallow layers and are concentrated on a very narrow frequency band, while higher mode data are more sensitive to the parameters of relatively deeper layers and are distributed over a wider frequency band. These properties provide a foundation of using a multimode joint inversion to define S-wave velocities. Inversion results of both synthetic data and a real-world example demonstrate that joint inversion with the damped least-square method and the singular-value decomposition technique to invert high-frequency surface waves with fundamental and higher mode data simultaneously can effectively reduce the ambiguity and improve the accuracy of S-wave velocities.     

基础地理数据库建设与地形图生产

本文根据现有城市基础地理数据库建设中分比例尺对于应用所产生的问题进行了分析,提出将市域范围最大比例尺的地理空间数据融合于一个数据库中,形成多数据源基础地理数据库,以利于基础地理数据的生产、管理和应用进行了初步的研究和探讨.     

用光电等高仪Ⅰ型的观测建立连续的赤纬系统──临潼－伊尔库茨克等高仪国际合作观测的意义

本文提出了利用陕西天文台光电等高仪Ｉ型和伊尔库茨克合作观测的建议。由于该仪器将配备Ｚ＝４５°的角镜，放在＝５２°的纬度上，就可以消除等高仪测定赤纬的盲区，从而可对建立基本参考系及将来维持伊巴谷星表系统做出重要贡献。     

遥感水文应用中的尺度问题

遥感技术在水文科学中的广泛应用，极大地拓宽了其研究的领域和范围，增加了其研究的深度。但同时也应该看到，遥感信息的空间分辨率和时间分辨率，以及水文科学自身尺度问题的复杂性，一方面对遥感水文的应用产生困难和问题，限制了水文遥感的应用；另一方面又对水文尺度问题提供了新的技术手段，为遥感水文应用增添了新的亮点。从水文机理与空间尺度、遥感信息的空间分辨率、水文参数的空间延拓，以及遥感技术与水文科学的发展等 4个方面探讨了遥感水文的空间尺度问题；从瞬时遥感信息的时间拓展和遥感信息的时间分辨率 2个方面讨论了遥感水文的时间尺度问题。     

Fundamental period and mode shape of layered soil profiles

The estimation of the fundamental period of soil profiles has been the subject of numerous studies. An extensive evaluation of several procedures by Dobry et al. [1] concluded that both the Simplified Version of the Rayleigh Procedure [1] and the Successive Use of Two-Layer Solution by Madera [2] give errors of less than 10% for all of the 76 representative soil profiles considered in the evaluation. The simplified Rayleigh procedure is iterative and requires an initial estimate of the mode shape. The Madera procedure is based on the solution of a two-layer system, usually obtained from charts. In this paper the solution charts are replaced by approximate relations for implementation on a spreadsheet. Since the Madera procedure calculates only the fundamental period, mode shapes need to be calculated by other means. The Madera procedure is extended to calculate mode shapes and modal participation factors of layered soil profiles. Unlike the simplified Rayleigh procedure [1], the proposed solution incorporates the different densities of the layers and gives direct results without iterations. The proposed solution can be considered a simpler alternative to the Rayleigh method for shear beams or soil columns.     

西部地区生态环境建设的若干问题与政策建议

西部地区是我国生态环境的脆弱地区，生态建设是西部地区开发建设必须首先研究和解决的一个重大问题。西部地区生态环境十分复杂，西北地区和西南地区的自然生态环境迥异、生态退化问题千差万别，对西部地区的生态环境的基本现状进行了评价，提出了生态环境建设的目标，分析了生态环境建设中面临的亟等研究和解决的科学、技术和社会经济问题，并提出了生态环境建设的若干政策建议，并特别指出，应充分发挥科技对生态建设的支撑作用，科学实施生态建设工程；必须采取基于不同生态经济类型区的自然生态环境特点和生态退化问题的分类指导的生态建设策略；建立西部地区生态安全体系，开展西部地区生态建设和环境保护立法，以实现西部地区生态环境与经济社会的协调可持续发展。