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81.
Many existing reinforced concrete buildings located in seismic regions are characterised by internal steel reinforcement made of smooth bars and stirrups with inadequate spacing. These bars could be subjected to significant compression and eventually buckle. This paper deals with a comprehensive experimental campaign investigating the compressive behaviour of smooth bars for different values of the ratio L/D, L being the restraints distance and D the bar diameter. The stress-strain relationship is then modelled ranging from an elastic-plastic behaviour identical to that in tension (L/D=5) to the elastic buckling behaviour (L/D>20). The comparison between the experimental results and the outcomes of the model confirms the accuracy of the proposed stress-strain relationship. 相似文献
82.
We examine the Lapita colonization of east Fiji from the frequency of pottery designs. The design frequency analysis suggests that east Fiji was settled by Lapita groups emanating from west Fiji and Tonga, and long‐distance interaction with archipelagos to the west of Fiji was inconsequential during the terminal Lapita phase when east Fiji, Tonga and Samoa were colonized. The results have important implications for understanding Lapita colonization elsewhere, particularly the extent to which migrant communities interacted and expressed identity in the varied physical and social environments encountered during dispersal. 相似文献
83.
RONNIE DONALDSON NICO KOTZE 《Tijdschrift voor economische en sociale geografie = Journal of economic and social geography = Revue de géographie économique et humaine = Zeitschrift für ?konomische und soziale Geographie = Revista de geografía económica y social》2006,97(5):567-582
This paper revisits the city of Pietersburg more than ten years after the repealing of the Group Areas Act in order to determine the extent to which the socio‐spatial impress of apartheid segregation has been changed. The socio‐spatial changes that have taken place in the city were brought about mainly through residential desegregation. The scrapping of the Group Areas Act in 1991 saw the movement of blacks into the city's former white, Indian and coloured suburbs. Initially the percentage in this regard was low: in 1992 the city's suburbs were one per cent desegregated. Ten years later, the city's desegregation level had increased to 32 per cent. In all neigbourhoods except three, the number of black property‐owners had doubled. New Pietersburg remained undeveloped until informal squatters invaded it in the 1990s after the fall of apartheid. This area was earmarked for the development of low‐income housing units in the 1997 Land Development Objectives. More than 300 land claims were lodged at the time. Because of the complexity of land claims and urban restructuring, the problem was still unresolved by 2005. 相似文献
84.
Wang Yi Fu Qiang Xu Honghe Hao Shougang 《Alcheringa: An Australasian Journal of Paleontology》2013,37(2):111-120
Wang Yi, Fu Qiang, Xu Honghe, & Hao Shougang, June, 2007. A new Late Silurian plant with complex branching from Xinjiang, China. Alcheringa 31, 111-120. ISSN 0311-5518. A new fossil plant is described from the middle part of the Wutubulake Formation (late Pridoli) of Xinjiang, China. This plant demonstrates at least two orders of branching. The first-order axis has pseudomonopodial branching with alternately attached second-order axes. Fertile units are alternately inserted along the second-order axis, and consist of a branching system and two sporangia at each tip. Sporangia are narrowly obovate with rounded apex and tapering base. This plant is characterized by more complex branching than other Silurian and Early Devonian plants, and is named Wutubulaka multidichotoma gen. et sp. nov., and placed under open higher-order nomenclature. 相似文献
85.
Obama's election in 2008 as the United States’ first self-styled Pacific President drew a hearty round of ‘end of the affair’ editorials about Anglo-American relations. His first term was littered with ‘snubgates’, serious irritations in policy areas regarded as being core to the special relationship, and indications of an accelerating US departure from Europe with his premier foreign-policy strategy declared to be a pivot to Asia. His return for a second term in 2013 augers a continuation of first-term adjustments in US foreign policy and greater domestic focus given a divided Congress and a bitterly split and war-weary United States with domestic priorities to the fore. Doomsayers - or so-called terminalists - have been repeatedly gainsaid by the Lazarus-like quality of the relationship in the past but can the Anglo-American special relationship survive in the Obama environment? This article suggests it can and sets out the author's rather unfashionable argument in four parts: the weight of history; the canons of international-relations theory; the importance of considering interest and sentiment in explaining the special relationship's resilience; and a relativist argument that suggests the United States still really does have no better ally than the United Kingdom. 相似文献
86.
《African Historical Review》2013,45(1):121-160
Abstract One of the basic areas of interaction between water as natural resource and human societies as agents of cultural transformation is the technology of irrigation. In Africa at least 66 per cent of the available water is used for purposes of irrigation. For more than 4 000 years irrigation has secured food supplies for humans on a continent that is noted for its relative shortage of sufficient natural water supplies. There is a remarkable hidden power of water in the history of southern Africa. This is particularly the case when we consider the development of early irrigation technologies of Iron Age farmers. The small irrigation furrow of the subsistence farmer was just as important to an insular community of Bantu-speaking people in pre-colonial times, as is the sophisticated irrigation technology in present-day South Africa. Currently there is a paucity of information about pre-colonial indigenous irrigation technology. This can be ascribed to a number of factors of which the invasion of modern Western traditions in the nineteenth century is perhaps the most important. A number of other factors for the apparent blind-spot is also presented in this study. In southern Africa there are traces of indigenous pre-colonial irrigation works at sites such as Nyanga in Zimbabwe; the Limpopo River Valley; Mpumalanga; and South Africa's eastern Highveld. Reference is also made in this article to specific strategies of irrigation used by Iron Age communities, prior to the advent of a colonial presence. Finally, attention is also drawn to pre-colonial land tenure and state formation against the backdrop of Wittfogel's theories on hydraulic society. 相似文献
87.
IAN DOUGLAS 《Geographical Research》2006,44(2):123-134
Economic globalisation has led to a huge increase in demand for food, goods and services by expanding urban middle class populations. These demands cause environmental changes that in turn feed back upon the urban environment and human population. While the global changes are well researched, the cumulative significance of local environmental changes is less well known. Yet, the local changes may have greater impact on the decisions which individuals make that affect soil erosion and land degradation. People respond to family circumstances and to local economic opportunities in ways that most suit the needs of their families and households. Several demonstration projects that were not adopted offer lessons in understanding how people make their land‐use decisions. An understanding of people's past experiences, present needs and views of the future helps those seeking to improve environmental management to promote policies and actions that are likely to succeed by being acceptable to those involved. 相似文献
88.
ERIC KOOMEN TOM KUHLMAN JAN GROEN ARNO BOUWMAN 《Tijdschrift voor economische en sociale geografie = Journal of economic and social geography = Revue de géographie économique et humaine = Zeitschrift für ?konomische und soziale Geographie = Revista de geografía económica y social》2005,96(2):218-224
The agricultural sector in the Netherlands has lost much of its importance over the last 50 years in terms of the number of people involved and its relative contribution to the economy – even though production is still increasing. Yet, the area under agricultural use has changed relatively little: farmland still dominates the country. The question for the future is how expected further changes in agriculture will affect agricultural land use: how much land will be taken out of production and to what use it will be put. This is especially relevant now that the Dutch Government has decided to loosen its grip on spatial planning. Two opposing socio‐economic scenarios are therefore drafted that offer a coherent view on agricultural change, external pressures and government intervention. Implementing these in a land use simulation model provides an initial answer to the possible future of agricultural land in the country. 相似文献
89.
90.
Joseph A. Yaro 《Geografiska annaler. Series B, Human geography》2012,94(4):351-368
In northern Ghana periurban areas are encroaching on rural areas and agricultural land ends up being sold for residential purposes mainly by chiefs and “earth” priests. The changing customary land tenure systems have generated a state of uncertainty and tension as the title and responsibilities of titleholders are subject to the interpretation by those who administer custom. Increasing commodification is taking place that benefits an emerging political‐traditional and economic elite. The centralized systems restrict the benefits of the commoditization process mainly to chiefs and their collaborators, whiles acephalous systems allow more space for objections and struggles by those whose land is expropriated. Neoliberal development policies have shaped the commodification of land and entrenched existing socio‐economic inequalities that marginalize the poor who are unable to seize the opportunities of the emerging urban economy. 相似文献