Plastic buckling of ring-stiffened conical shells under external hydrostatic pressure

The paper describes experimental tests carried out on three ring-stiffened cones that were tested to destruction under external hydrostatic pressure. The cones were carefully machined from EN1A Steel. All three cones failed by plastic non-symmetric bifurcation buckling in a mode commonly known as general instability. In this mode the entire ring-shell combination buckles bodily.The paper also provides a design chart using the results obtained from these three vessels, together with the results of six other vessels obtained from other tests. The design chart allows the possibility of obtaining a plastic knock down factor, so that the theoretical buckling pressures, based on elastic theory, can be divided by the plastic knockdown factor, to give the predicted buckling pressure. This method can also be used for the design of full-scale vessels.     

The acquistion and application of basic land use data in urban growth analysis: A case study of Metropolitan Lagos

Basic to the study of urban growth is information on population and land use changes. These basic data are generally lacking in Nigeria. This paper examines and assesses the growth of urban land use of Lagos (the Federal Capital of Nigeria) through a systematic utilization of sequential serial photographs (taken in 1962 at a scale of 1:40,000, and in 1974, at a scale of 1:20,000) and computer techniques. The land use data resulting are then used in evaluating the population growth of Lagos. The resulting population estimate is then compared with the available population data. The study concludes by recommending the use of remote sensing, especially aerial photography for the acquisition of basic urban data not only in Nigeria but also in other developing countries lacking in such data.     

Preliminary Results from the Magnetic Field Measurements Using MAGDAS at Ilorin, Nigeria

MAGDAS, the Magnetic Data Acquisition System, was successfully installed at the University of Ilorin, Nigeria—an equatorial station—in August 2006. MAGDAS is an important component of the International Heliophysical Year, IHY. We examined the preliminary results obtained from the analysis of the geomagnetic data obtained from the MAGDAS measurement. Diurnal variations of the solar quiet daily variation in the three geomagnetic elements, H, D, Z were studied. The obtained signatures of the magnetic field variations were discussed in the context of the literature. The day-to-day variability of the horizontal and vertical intensities as well as the declination of the geomagnetic field were examined. The study justified the need for a partner magnetic field observatory along same meridian as Ilorin, north or south of it, to facilitate synthesis of the equatorial electrojet effect.     

Micrometeorological measurements in Nigeria during the total solar eclipse of 29 March, 2006

The total solar eclipse of 29 March, 2006 which was visible at Ibadan (7.55°N, 4.56°E), south-western Nigeria was utilized to document atmospheric surface-layer effects of the eclipse for the first time in Nigeria. The meteorological parameters measured are global radiation, net radiation, wind speed (at different heights), atmospheric pressure and soil temperature (5, 10 and 30 cm), moisture and heat flux and rainfall. The results revealed remarkable dynamic atmospheric effects. The observations showed that the incoming solar radiation, net radiation and air temperature were significantly affected.There was an upsurge of wind speed just before the first contact of the eclipse followed by a very sharp decrease in wind speed due to the cooling and stabilization of the atmospheric boundary layer. The atmospheric pressure lags the eclipse maximum by 1 h 30 min, while the soil temperature at 5 and 10 cm remain constant during the maximum phase of the eclipse.     

On the problems concerned in“The subter－ranean electrical conductivity structure at the ChineseGreatWalStationonAntarctic（CG┐WSA）”byXiaopingZeng，YunfangLinandYuechenZhao

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从跨国广告业看全球化和全球城市——以中国广告业为例

本文从广告业的视角出发 ,分析了伴随全球生产者服务业空间布局的扩张而来的区域市场和空间结构的重塑。研究的主要发现为 :(1)在跨国公司的支配下 ,中国广告业在生产组织上逐渐向专业代理演化 ,在行业规范上也逐渐向 4A的主流靠拢 ;(2 )中国广告业在上海、北京、广州三大城市的集中 ,体现了在全球化过程中形成的“区域性服务业市场” ;(3)由于市场规模大 ,中国广告业有可能向“前端” (产品定位和沟通策略 )发展 ;(4 )由于中国幅员广大 ,进入区域市场需要不同的媒体计划 ,也使得广告的全球标准化产品产出更多的地方版本。在理论争论方面 ,本文认为全球城市是都市区域全球化制度和空间的中介。     

A brief note on remote sensing activities in Nigeria

Abstract

Orbital photography from the Space Shuttle missions (1981–88) and earlier manned spaceflight programs (1962–1975) allows remote sensing time series to be constructed for observations of environmental change in selected portions of the global tropics. Particular topics and regions include deforestation, soil erosion, supersedimentation in streams, lacustrine, and estuarine environments, and desertification in the Greater Amazon, Tropical Africa and Madagascar, South &; Southeast Asia, and the Indo‐Pacific archipelagoes.     

Electron density distribution at fixed heights N(h): Gaussian distribution test

Occurrence probability distribution (Gaussian distribution) test was carried out at selected fixed heights on the electron density profile, N(h), for selected hours around midday and midnight from representative months within 1995 and 1999/2000. The main objective of this work is to investigate the normality of the frequency distribution of the data sets around the mean value. Although the distribution is not perfectly symmetrical about the mean value, the results show that the percentage of data within ±1 standard deviation of the mean is at least 69% between 100 km and the F2 peak height around midday and midnight for all the selected hours and for the two years investigated.     

Integrated Futures for Europe’s Mountain Regions: Reconciling Biodiversity Conservation and Human Livelihoods

Introduction Europe's mountains cover nearly half of the continent's area (Price et al. 2004) and land cover varies significantly (European Commission 2004). In most massifs, except for Sicily, southern Greece, and the British Isles, forest cover is dominant. In northern Europe, grassland is proportionately more important, and much of the mountains of the British Isles is covered by moorland. In central and southern Europe, arable land is of far greater importance than grassland, with Med…