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1.
Muyiwa Ebenezer Alalade Binod Kafle Frank Wuttke Tom Lahmer 《Geomechanics and Geoengineering》2018,13(2):146-157
Most structures are subjected to more cyclic loads during their life time than static loads. These cyclic action could be a result of either natural or man-made activities and may lead to soil failure. In order to understand the response of the foundation and its interaction with these complex cyclic loadings, various researchers have over the years developed different constitutive models. Although a lot of research is being carried out on these relatively new models, little or no details exist in literature about the model-based identification of the cyclic constitutive parameters which to a large extent govern the quality of the model output. This could be attributed to the difficulties and complexities of the inverse modeling of such complex phenomena. A variety of optimisation strategies are available for the solution of the sum of least-squares problems as usually done in the field of model calibration. However, for the back analysis (calibration) of the soil response to oscillatory load functions, this article gives insight into the model calibration challenges and also puts forward a method for the inverse modeling of cyclic loaded foundation response such that high-quality solutions are obtained with minimum computational effort. 相似文献
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This paper examines how extreme weather events affect the mobility of low-income urban residents in Ghana. Bringing together scholarship on extreme weather and mobilities, it explores the differential impact of flooding on their everyday lives as they navigate the cities of Accra and Tamale. A range of qualitative methods were drawn on, including semi-structured interviews, focus group discussions, and follow-along-participant observations in selected communities of both cities. Three key themes emerged: disrupted road and transport infrastructure, everyday mobility challenges, and coping/adaptive strategies. In flooding conditions, residents experienced difficulties leaving/returning home, engaging in income-generating activities, and accessing transport services and other key urban infrastructure. Conceptually, the paper reveals how disruption to urban residents’ daily movements and activities (re)produces new forms of mobilities and immobilities, which have three relational elements: postponed, improvised and assisted. Throughout the analysis, we show how these mobilities/immobilities vary by age and gender: all urban residents, (though women in particular), experience postponed mobility; young people especially engage in improvised mobility; and children and the elderly are in greatest need of assisted mobility. The paper thus contributes to scholarship on extreme weather events and mobility by providing a more spatially nuanced understanding of the multi-faceted domains in which flooding, socio-economic conditions and adaptive strategies intersect to influence urban mobility in resource poor settings. 相似文献
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Benony K. Kortatsi Collins K. Tay Geophrey Anornu Ebenezer Hayford Grace A. Dartey 《Environmental Geology》2008,53(8):1651-1662
Alumino-silicate mineral dissolution, cation exchange, reductive dissolution of hematite and goethite, oxidation of pyrite
and arsenopyrite are processes that influence groundwater quality in the Offin Basin. The main aim of this study was to characterise
groundwater and delineate relevant water–rock interactions that control the evolution of water quality in Offin Basin, a major
gold mining area in Ghana. Boreholes, dug wells, springs and mine drainage samples were analysed for major ions, minor and
trace elements. Major ion study results show that the groundwater is, principally, Ca–Mg–HCO3 or Na–Mg–Ca–HCO3 in character, mildly acidic and low in conductivity. Groundwater acidification is principally due to natural biogeochemical
processes. Though acidic, the groundwater has positive acid neutralising potential provided by the dissolution of alumino-silicates
and mafic rocks. Trace elements’ loading (except arsenic and iron) of groundwater is generally low. Reductive dissolution
of iron minerals in the presence of organic matter is responsible for high-iron concentration in areas underlain by granitoids.
Elsewhere pyrite and arsenopyrite oxidation is the plausible process for iron and arsenic mobilisation. Approximately 19 and
46% of the boreholes have arsenic and iron concentrations exceeding the WHO’s (Guidelines for drinking water quality. Final
task group meeting. WHO Press, World Health Organization, Geneva, 2004) maximum acceptable limits of 10 μg l−1 and 0.3 mg l−1, for drinking water. 相似文献
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Collins K. Tay Benony K. Kortatsi Ebenezer Hayford Isaac O. Hodgson 《Environmental Earth Sciences》2014,71(12):5079-5097
Hydrochemical and stable isotopes (18O and 2H) analyses of groundwater samples were employed to establish the origin of major dissolved ions in groundwater within the Lower Pra Basin. Results showed that, the major processes responsible for chemical evolution of groundwater include: silicate (SiO4)4? dissolutions, ion exchange reactions, sea aerosol spray and pyrite (FeS2) and arsenopyrite (FeAsS) oxidations. The groundwater is strongly acidic to neutral, with pH generally range from 3.5 to 7.0 pH units and mean 5.9 (±0.5). Approximately 89 % of boreholes had pH values outside the World Heath Organization (WHO, Guidelines for drinking water quality, 2004) guideline value for drinking water due principally to natural biogeochemical processes and therefore, not suitable for potable purposes. Electrical conductivity (EC) range from 57.6 to 1,201 μS/cm with mean 279.3 (±198.8) μS/cm. Total dissolved solids (TDS) range from 32 to 661 mg/L with mean 151.7 (±106.8) mg/L, with 98.6 % of groundwater as fresh (TDS < 500 mg/L). The chemical constituents generally have low concentrations and are within the WHO (Guidelines for drinking water quality, 2004) guideline value for drinking water. The relative abundance of cations and anions is in the order: Na+ > Ca2+> Mg2+ > K+ and HCO3 ? > Cl? > SO4 2?, respectively. A plot of ?18O ‰ against 2H ‰ showed that, ground and surface waters clustered on or closely along the Global Meteoric Water Line, suggesting that, the waters emanated principally from meteoric source with evaporation playing an insignificant role on the infiltrating water. 相似文献
6.
Ebenezer Yemi Ogunbadewa 《国际地球制图》2013,28(7):593-610
The aim of this study is to derive environmental factors that are likely to influence malarial distribution from Nigeriasat-1 in a geographical information systems (GIS) environment and relate it to the empirical evidence of reported malarial cases in the hospitals using discriminant analysis (DA) to characterize, identify and map malarial risk zones. It is found that using a stepwise DA, Nigeriasat-1 and GIS it is possible to classify the accurately the low malarial risk zone (100%), medium and high risk zones (83.33%), with an overall accuracy of 88.9% being achieved for the study area. The results obtained were in agreement with the ground validation exercise that was carried out and the cross validation method of ‘‘leaving-one-out’ in DA function. These findings indicate that Nigeriasat-1 and GIS combined with statistical technique of DA can be utilized as a decision support tool for a precise identification of the areas warranting mitigation efforts. 相似文献
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H. S. Sawant R. Ramesh J. R. Cecatto C. Faria F. C. R. Fernandes R. R. Rosa M. C. Andrade S. Stephany L. B. T. Cividanes C. A. I. Miranda L. C. L. Botti J. W. S. V. Boas J. H. Saito C. E. Moron N. D. Mascarenhas K. R. Subramanian M. S. Sundararajan E. Ebenezer M. R. Sankararaman 《Solar physics》2007,242(1-2):213-220
An East – West, one-dimensional radio interferometer array consisting of five parabolic dish antennas has been set up at Cachoeira
Paulista (longitude 45°0′20″ W, latitude 22°41′19″ S) for observations of the Sun and some of the strong sidereal sources
by the Instituto Nacional de Pesquisas Espaciais (INPE), Brazil. This is Phase-I of the proposed Brazilian Decimetric Array
and can be operated at any frequency in the range 1.2 – 1.7 GHz. The instrument has been in operation since November 2004
onwards at 1.6 GHz. The angular and temporal resolutions at this frequency are ∼3′ and 100 ms, respectively. Details of the
array, analog/digital receiver system, and a preliminary East – West one-dimensional solar image at the 1.6 GHz are presented
in this paper. 相似文献
8.
Martin Oteng-Ababio Ian Smout Ebenezer Forkuo Amankwaa James Esson 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2017,117(2):142-154
AbstractIn most developing countries, the provision of municipal services and infrastructure invariably fails to match the pace and demands of urbanization. The outcome is often increased informality due to improper planning, official bureaucratic barriers and perhaps insufficient and shrinking public resources, which then makes leveraging private capital for public service provision imperative. Drawing on in-depth qualitative fieldwork in two Ghanaian cities, this paper aims to extend literature on the divergence between service provision and urbanization in developing countries. More specifically, it attempts to qualify recent macro-level data indicating that access to water, sanitation and electricity services in Accra and Sekondi-Takoradi is improving substantively. Contrary to dominant policy narratives circulating in Ghana, we illustrate how the acceptability of key municipal services within urban settings is often inadequate, and how acceptability is tied to spatial and temporal factors. We then identify and examine the reasons underpinning these variations. Through exploring residents’ perceptions of key services, and examining critically the possibility and feasibility of meeting urban service needs through leveraging private resources, this paper contributes to broader academic debates over urban service provision, while also feeding into contemporary policy discussions concerning how to achieve several of the Sustainable Development Goals by 2030. 相似文献
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Cultural and Geographical Influences on Underweight Prevalence among Preschoolers in Ghana 
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下载免费PDF全文 Ebenezer G. A. Nikoi 《Geographical review》2018,108(3):367-386
Underweight prevalence among preschool children in Africa has been studied, but the effects of culture and geography remain unclear. This study used the 2008 Ghana Demographic and Health Survey data for 2244 children aged 0‐59 months and generalized linear mixed models to analyze these data. The results showed that culture and geography remained significantly associated with preschool underweight prevalence after controlling for demographic and socioeconomic characteristics of children, mothers, and households. Additionally, the gender of a child, size at birth, fever status, mother's BMI, insurance coverage and number of children <5 years in the household were significantly associated with underweight prevalence in Ghana. The study concluded that in addition to specific characteristics of children, mothers, and households, culturally motivated childhood dietary restrictions among the Ga/Dangme and Ewe could be reduced through appropriately targeted nutritional messages. Additionally, decreasing North‐South disparities in socioeconomic development, and improving nutritional outcomes among disadvantaged households in southern Ghana should be the focus of policies and strategies directed at reducing preschool underweight prevalence in Ghana. 相似文献
10.
We recently investigated some of the hitherto unreported observational characteristics of the low frequency (85–35 MHz) type III–V bursts from the Sun using radio spectropolarimeter observations. The quantitative estimates of the velocities of the electron streams associated with the above two types of bursts indicate that they are in the range \({\gtrsim }0.13c\)–0.02c for the type V bursts, and nearly constant (\({\approx }0.4c\)) for the type III bursts. We also find that the degree of circular polarization of the type V bursts vary gradually with frequency/heliocentric distance as compared to the relatively steeper variation exhibited by the preceding type III bursts. These imply that the longer duration of the type V bursts at any given frequency (as compared to the preceding type III bursts) which is its defining feature, is due to the combined effect of the lower velocities of the electron streams that generate type V bursts, spread in the velocity spectrum, and the curvature of the magnetic field lines along which they travel. 相似文献