用创新思维破解风沙运动机理——两种理论体系核心的剖析

从地理学视角首次将风沙运动分解为内核和外延两部分,提出沙粒起动是风沙运动的内核,将沙粒起动后的一切输移表现界定为外延。流体起动和跃移质冲击起动是构成内核的两个实体。利用这一创新理念,对风沙物理学和风沙地理学两种理论体系的不同核心展开讨论。结果表明:能否区分内核两个实体的不同本质属性和能否摆正两个实体的互动机理是导致两种理论不同核心的形成和出现许多分歧的根源。本文深化了对风沙运动内涵的理解,从理论上突破了R.A.拜格诺长期用一扬一贬沙粒两种起动观引领沙坛学术潮流的核心理念。     

影响拜格诺结的若干因素分析

给出了全面描述风沙耦合作用下沙粒跃移运动的理论模型,利用数值方法对风沙耦合作用以及空气上升力、Magnus力、静电力等因素对沙粒跃移运动和风速廓线的影响进行了研究,从而揭示出拜格诺结(Bagnold's Kink)高度与其对应的风速及沙粒跃移高度的关系。     

地表粗糙度的含义本质

阐述了粗糙度理论含义本质,并提出了应用拜格诺方法确定地表粗糙度的条件。     

以计算流体动力学模型（CFD）模拟的戈壁地表风沙两相流运动特征

尘暴过程中沙砾质戈壁地表的风沙两相流运动,一直是风沙物理学关注的问题。但由于技术限制,野外观测及风洞实验难以捕捉大规模颗粒运动。为此,本文通过构建流体-颗粒碰撞互馈模型进行三维场域数值模拟,分析了不同砾石盖度下尘暴来流中的风沙两相流运动规律。结果表明：基于三维场流体-颗粒碰撞互馈模型修正后的求解结果能够较为准确地模拟戈壁地表风沙两相流运动过程。(1)不同来流尘暴过程,风相速度均会随砾石盖度的增大而减小,并在砾石盖度大于40%的戈壁近地表形成拜格诺焦点。相较于风相,沙相降速不明显。此外,距砾石床面4 cm以上,风沙两相速度基本保持一致。(2)当尘暴速度大于10 m·s^-1时,在距地1.5～2.1 m高度形成风沙两相流速度交点,交点上下表现为“风快沙慢”及“风慢沙快”现象。(3)尘暴过程中近地表沙尘浓度沿均值线呈“脉动”规律,表现为地表粉尘沉降与再释放循环过程,同时砾石盖度大小会直接影响沙尘沉积分布,当盖度大于40%时能够有效抑制沙尘释放。     

蒋家沟泥石流阻力的无量纲参数分析

流速作为泥石流防治工程的重要参数之一,泥石流阻力的大小对其计算过程至关重要.但关于泥石流内部应力变化对阻力影响的研究甚少.本文利用东川蒋家沟泥石流观测数据,反算曼宁系数来表达泥石流运动过程中受到的综合阻力,并利用拜格诺数、萨维奇数和摩擦数三个无量纲参数,分析它们和阻力之间的关系.结果表明:粘性和稀性泥石流的拜格诺数和萨...     

中国风沙物理研究50a(Ⅱ)

1998年初中国科学院知识创新工程得到了国家的批准,在建设国家创新体系的战略背景下,风沙物理研究得到了新的发展机遇。为了适应国家创新体系的要求,风沙物理学首先重新凝练了学科方向和目标,改善研究手段、拓展研究内容、创新研究思路,使我国风沙物理学研究的国际影响不断增加。笔者从风沙颗粒运动、风沙流、风沙边界层、风沙地貌动力学、土壤风蚀、防沙工程原理和风沙电等几个方面比较全面地回顾了中国科学院知识创新工程实施以来,我国风沙物理学研究所取得的主要成就。     

风沙物理学学科建设的若干问题

风沙问题日益严重,以风沙活动及其控制的物理机制为对象的风沙物理学学科建设亦愈来愈加重要。本文阐述了风沙物理学的研究对象、性质、理论体系、研究内容、目前存在的问题和亟待解决的问题,供风沙物理学研究者参考。     

风沙流中颗粒跃移研究的某些进展与问题

风沙流研究是风沙物理学的主要内容,研究方法上大致分宏观和微观研究两个方面。宏观研究着眼于风沙流的整体结构和动力学过程,微观研究侧重于单一颗粒的运动状态。宏观和微观研究相结合是解决风沙物理学中一系列问题的一条合理路线。但长期以来,由于在颗粒运动机理研究方面进展缓慢且不成熟,对联系宏观和微观研究的纽带——起跳粒子的运动状态分布的重要性认识不够,造成风沙流宏观研究和微观研究的严重脱节。本文综述国内外在这两方面的研究历史和现状,指出了现存问题和解决途径,并对风沙物理学的发展方向提出了一些建议。     

中国风沙物理研究五十年(Ⅰ)

2005年中国沙漠研究已经走过了50a的历程,作为沙漠科学重要组成部分的风沙物理学研究在中国亦有50a的历史了。本文较为详细地全面回顾了20世纪50年代中后期至90年代后期中国科学院知识创新工程实施之前我国风沙物理研究所做的主要工作和取得的成就,以期对相关的研究者有所帮助。这一时期的工作可以分为两个阶段。20世纪50年代中后期至60年代中期为理论准备和野外观测积累阶段,引进西方和前苏联在风沙物理学方面的研究成果,配合我国防沙治沙实践的需要开展野外观测研究。研究手段以大面积考察、半定位试验观测和定位试验为主。研究成果体现在风沙移动规律的初步认识、沙丘移动规律、中国沙丘活动的总体规律、防沙措施的布设原则和风沙运动理论的初步探讨等几个方面。1967年我国第一个风沙环境风洞建成使用,使风沙物理学的实验研究成为可能。自20世纪80年代开始同时向微观领域深入和向宏观领域扩展,风沙颗粒运动学、风沙流、风沙地貌动力、土壤风蚀和防沙原理等风沙物理学的主要领域得到了全面发展,在一些前沿探索领域亦有重要成就。     

新月形沙丘形成赛夫沙丘的讨论

前言由新月形沙丘的沙丘角伸长而形成的赛夫沙丘是众所周知的现象,这在世界沙漠的很多地方都得到了证实(Kerr & Nigra 1952,Holm 1960,Norris 1966,Clos-Arceduc1967,1969,Tsoar 1979,Warren 1976,Grolier et al.1979,Lancaster 1980)。解释这个现象的模型是由拜格诺(Bagnold 1941:223)提出的。后来人们在许多科学研究及教科书中都参考这一模型(即:Verstappen 1968:201,Ruhe 1975:155,Goudie& Wilkinson 1977: 37,Mabbutt 1977:236)。拜格诺把此模型看作是为进一步的研究     

王成组教授及其对中国地理学的贡献

王成组教授(1902～1987年)是我国老一辈地理学家,他一生有五十八个春秋都是从事地理教育和研究工作,为我国科学地理学的发展,做出了重要贡献。     

Revisiting the 'pivot': the influence of Halford Mackinder on analysis of Uzbekistan's international relations

Since the end of the Soviet Union, many foreign policy intellectuals have peculiarly identified the Republic of Uzbekistan as the locus of Mackinder's 1904 'pivot' designation. A century on from his original 'Geographical pivot of history' lecture, this paper examines the work of a Russian, an Uzbek, and an American who use Mackinder to understand contemporary Uzbekistani geopolitical orientations, in particular with reference to the USA. Drawing on critical work on the history of geopolitics, it highlights that whilst these texts claim objectivity, they betray political and subjective foreign policy choices. It suggests that whilst the revival of interest in Mackinder testifies to the continued attraction of his ideas, this has, with rare exceptions, been based upon a superficial reading of both his work and the body of secondary literature, and that this raises both disciplinary and ethical concerns.     

Griffith Taylor's ‘palimpsest theory’ of the dry valleys of Victoria land,antarctica

Griffith Taylor was the first geomorphologist to work in the Dry Valleys of southern Victoria Land, Antarctica. Following his field work in February 1911, he proposed a multistage model in which earlier cirque erosion was later swamped by expanding outlet glaciers. Subsequently these glaciers retreated leaving the present form of the valleys. The topography retained the imprint of each episode, hence his name ‘palimpsest theory’. I summarise later research and compare Taylor's theory with current views.     

Prelude to Brazil: Leo Waibel's American Career as a Displaced Scholar

Beyond Germany, Leo Waibel (1888–1951) built a distinguished reputation for his work in Africa and the Americas. Today he is remembered especially in Brazil, where he boosted the development of geography as a research discipline in the years 1946–1950. During his tenure of the chair in geography at Bonn (1929–1937), Waibel's main research preoccupation became the role of the tropics in the world economy. In early 1937, he sought research leave to make an extended field trip to Brazil. Stripped on political grounds in the same year of his chair, Waibel came to the United States, where he became the only geographer to receive help from the Emergency Committee in Aid of Displaced Foreign Scholars. He would eventually serve as one of the very limited core staff on President Franklin Roosevelt's “M” Project on migration and settlement. This paper reconstructs the context of his work in the United States, clarifying especially the nature of his collaborations with Isaiah Bowman, widely regarded at the time as the leading geographer within the United States. Waibel's correspondence from the United States, and later from Brazil, reveals an international career marked by contradictions.     

孟德斯鸠是“地理环境决定论”者吗？

孟德斯鸠是18世纪法国启蒙时期的思想家,他的《论法的精神》是他一生研究的最后结晶,于1748年出版,中译本于1961年分上下两册出版。由于孟德斯鸠在上册第3卷的第14至18章长篇大论地讨论了自然地理环境中气候、土壤要素与法律的关系,从而被后人误认为地理环境决定论者。中外学者对此误识都曾明确地指出和纠正过,愿此错误不再延续下去。     

Pow Choon-Piew's contributions to urban China studies

This commentary serves as a tribute to the late Pow, a remarkable scholar in urban geography and urban studies, summarizing his contributions to urban China studies. It aims to showcase the way in which Pow's work manoeuvred adroitly with an implicit comparative gesture—building a bridge between situated Chinese cases and wider theoretical debates in urban studies in order to enrich both domains. The essay then summarizes Pow's work in the field of urban China studies by focusing on two most emblematic topics that he delved into in great depth, i.e., gated communities and eco-city developments. The final section develops a brief quantitative analysis of the impact that Pow's work has generated. Using the software packages CiteSpace and HistCite, I unpack how his publications are cited and used by scholars, journals, and different areas of research.     

GEOGRAPHY AS MELODY IN MUTTUSVAMI DIKSHITA'sINDIAN MUSICAL WORKS*

ABSTRACT. The life and works of Muttusvami Dikshita (1775–1834), a luminary of South Indian Karnatak classical music, abound in spatiocultural symbolisms of integration and harmony. Dikshita'speregrinations symbolize a cultural circuit of Hindu pilgrimage. His studies of North Indian Hindustani music at Varanasi (formerly Benares), and his transplantation of them throughout South India, make him an active agent of cultural diffusion, harmonizing cultural traditions through spatiosymbolic anchors. The religious expression of his musical genius, his songs, and his melodies contributed to linking linguistically and politically disparate regions of eighteenth‐ and nineteenth‐century India. The works of Dikshita affirm India'scultural continuity and underscore its enduring cultural empathies and similarities.     

THE ARTIST AS GEOGRAPHER: RICHARD LONG'S EARTH ART

The sculptor Richard Long practices a variety of art based largely on taking walks around the countryside. He documents his expeditions by making his route on a map, taking a representative photograph, or making a word “poster.”Assemblages of rocks or other materials are exhibited in galleries. His work shows a subtle understanding of esthetic aspects of the landscape in developing an artistic sense of “place”from which geographers may learn much about perception.     

Seedbed of Reform: Arnold Guyot and School Geography in Massachusetts, 1849–1855

Abstract

Swiss-born Arnold Henri Guyot (1807–1884) was the first professionally trained geographer to hold an academic position in the United States. After his migration to this country in 1848 he lived for several years in Massachusetts. During this period he introduced contemporary German-Swiss ideas of geography to key opinion leaders in an important series of lectures (published as Earth and Man), established a system of weather stations, and lectured on methods of teaching geography in Massachusetts teachers' institutes and normal schools. This article discusses Guyot's work in the reform of school geography in Massachusetts as the seedbed for his later, better-known work as the author of innovative textbooks and other teaching aids.     

J. B. JACKSON AS A CRITIC OF MODERN ARCHITECTURE

ABSTRACT. Understanding what the American landscape meant to J. B. Jackson requires an exploration of his background, education, and antagonism to the International Style. No full critique of modernism appears in Jackson's mature published work. However, knowledge that the first issues of Landscape magazine in 1951 and 1952 were the work of a single author leads to discovery of Jackson's pseudonyms, especially H. G. West, P. G. Anson, G. A. Feather, and A. W. Conway. This article examines Jackson's pseudonymous writings and links them to his well-known essays on the landscape: “The Westward-Moving House,” “Other-Directed Houses,” and “Southeast to Turkey.”