Search

The Rockefeller Foundation shipped two Apple II computers with VisiCalc to the Tunisian Ministry of Agriculture to address a grain shortage in the early 1980s. The foundation believed that VisiCalc would enable the speedy and complex analytical modeling necessary to improve the management and, consequently, the production of grain resources. The foundation also argued that VisiCalc would empower individuals in the Ministry of Agriculture, improving their own analytical thinking as they became more familiar with the modeling capabilities of the software. Even with the use of VisiCalc, Tunisia experienced violent riots due to high bread prices after the government's removal of grain subsidies. This paper explores the narratives and uses of VisiCalc in the Tunisian Ministry of Agriculture in addressing this food crisis both before and after the riots. The work here contributes to computing history through an analysis of the historical relationships among governing bodies, nongovernment organizations, technology, and the global financial economy. It argues that the uses of VisiCalc in Tunisia were connected with financial austerity firmly aligned with Western interests. In doing so, this paper shows how a focus on postcolonial Africa can enrich the international history of computing. [ABSTRACT FROM AUTHOR]

Large dam projects (i.e., those exceeding 15 m) often make headlines for their poor performance and their negative social and environmental impacts. The world register characterizes dams by height, purpose (e.g., irrigation), and type (e.g., rock-fill). Thus, large dams differ in many technical ways, but because practitioners still lack a framework to sort them into different types for management purposes, they tend to manage them in a one-size-fits-all manner. Shenhar and Dvir's NTCP (novelty, technology, complexity, and pace) model (2007) may be a good fit as large dams experience high unforeseen technological uncertainty. In this paper, through observations, a case study, a qualitative analysis of 42 interviews with project managers, and a quantitative analysis, we examined 30 large dam projects in Africa and sorted them into different categories according to the NTCP model. Going beyond the rather static NTCP, we identified their underlying NTCP characteristics and the variety of roles that their project managers played throughout the lifecycle, and highlighted the dynamic fit between the roles and NTCP characteristics. Since different characteristics and project manager's roles are prominent at different phases, project managers should sort dams into different types based on the NTCP model at different phases, and tailor their roles accordingly for more success. [ABSTRACT FROM AUTHOR]

When a significant event occurs, many news articles from different newsagents often report it. Moreover, these newsagents also provide platforms for their readers to write comments expressing their views or understanding. Through digesting these reader comments, we can gain insights into the reactions, suggestions, personal experiences, or public opinions with respect to the emerging event. However, these reader comments from different sources are often rapidly accumulated resulting in an enormous volume. It becomes difficult to manually analyze these comments. In this paper, we propose a framework that can digest reader comments automatically through latent event facets and news specificity. An event facet refers to the aspect of the event concerned by many readers. Specifically, some of the reader comments, despite coming from different sources, discuss a certain facet of the event. Such facets provide an effective means for organizing news comments in a global manner. On the other hand, some comments discuss the specific topic of the corresponding news article. These specific topics demonstrate the specific focus of readers on the piece of news locally. Such reader comment digest in different granularities facilitates readers deeper understanding of these enormous comments. To achieve the above desirable goal of digesting reader comments, we propose an unsupervised model called EFNS which is capable of capturing the intricate fine-grained associations among events, news, and comments. We also develop a multiplicative-update method to infer the parameters and prove the convergence of our algorithm. Our framework can also visualize reader comments according to the relationship with latent event facets and the degree of news specificity. Experimental results show that our proposed EFNS model can provide an effective way to digest news reader comments and outperform the state-of-the-art method. [ABSTRACT FROM AUTHOR]

Low-voltage, low-power solar photovoltaic (PV) based dc microgrids are becoming very popular in nonelectrified regions of developing countries due to lower upfront costs compared to utility grid alternatives and limited power needs of rural occupants. The optimal planning of distribution architecture along with sizing of various system components such as solar panels, batteries, and distribution conductors is essential for minimizing the system cost and enhance its utilization. In this paper, we develop a framework for optimal planning and design of low-power low-voltage dc microgrids for minimum upfront cost. The analysis is based on region-specific irradiance and temperature profiles; constraints in storage and distributions; distribution loss analysis; and optimum component sizing (storage, conductor, and PV panel) requirements based upon an energy balance model for a 24-h operation. We further analyze the merits of tailoring distribution architecture for maximizing the system utility in the planning of future microgrid deployments. [ABSTRACT FROM PUBLISHER]

In this paper, we analyze the feasibility of applying the temperature and emissivity separation (TES) algorithm to thermal-infrared data acquired with three bands of the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard the Meteosat Second Generation platform (SEVTES). The performance of the SEVTES algorithm was tested using data simulated over different atmospheric conditions and surface emissivities, with errors around 1.5% for emissivity and 1.5 K for temperature when atmospheric correction is accurate enough. In contrast, errors on land-leaving radiances higher than 2% or uncertainties on total atmospheric water vapor amount higher than 5% lead to errors on emissivity higher than 2% and errors on land surface temperature higher than 3 K, especially when the atmospheric absorption is overestimated. SEVIRI data acquired in August 2011 were also used to validate SEVTES emissivities against in situ measurements collected in five different homogeneous areas over Africa. Values were also intercompared to Moderate Resolution Imaging Spectroradiometer (MODIS)-derived and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)-derived emissivities and to the LSA SAF emissivity product. Results show that SEVTES-derived emissivity values are consistent with MODIS-TES and ASTER-TES retrievals and that SEVTES also improves the retrievals included in LSA SAF and MOD11Cx v5 products. When compared to laboratory measurements, accuracies of around 1%-2% were obtained, although occasional inaccuracies (2%-3%) were also found in some cases at band 8.7 μm. The results presented in this paper show the potential SEVTES has for improving the LSA SAF product over arid and semiarid areas. [ABSTRACT FROM PUBLISHER]

This paper shows how to reconstruct the original 275-m resolution data of the Multi-angle Imaging SpectroRadiometer (MISR) instrument in the 24 spectrodirectional global mode channels that are spatially averaged to 1.1 km on-board the Terra platform, with negligible loss of information relative to images acquired in native-resolution local mode. Standard approaches to improve the spatial resolution of products rely on one (typically panchromatic) high-resolution (HR) image to sharpen multiple spectral images. In the case of the MISR-HR package described here, three of the 12 available HR channels are combined to regenerate each of the 24 reduced-resolution channel to its native resolution. The accurate and rigorously reconstructed spectral bidirectional reflectance data allow sensitive and physically meaningful land surface attributes to be recovered at a spatial resolution appropriate to document the spatial heterogeneity of the land surface and relevant for climate and environment studies. MISR has been in continuous operation since February 2000 and provides global coverage in at most nine days (depending on latitude). This technique allows the generation of quantitative information to monitor change and model ecosystem function virtually anywhere and at any time during the last decade. The potential is demonstrated for a savanna landscape in South Africa. [ABSTRACT FROM PUBLISHER]

The Japan Space Exploration Agency Kyoto and Carbon (K&C) Initiative seeks to demonstrate the potential of the Advanced Land Observing Satellite (ALOS) Phased Arrayed L-band Synthetic Aperture Radar (PALSAR) data for addressing regional applications relating to climate change, carbon cycle science, and environmental conservation. This paper outlines the generation of a regional dual-polarization (HH and HV) mosaic for the entire African continent at spatial resolution on the order of 100 m. The main computational and radar science issues undertaken to generate a seamless mosaic with good radiometric and geometric accuracy are summarized. Preliminary investigations into the thematic information provided by the K&C Africa mosaic and comparisons with the JERS-1 SAR mosaic generated as part of the Global Rain Forest Mapping Project are reported, with emphasis placed on characterizing and detecting change in forests and savannas. [ABSTRACT FROM AUTHOR]

Differences in within-species phenology and structure are controlled by genetic variation, as well as topography, edaphic properties, and climatic variables across the landscape, and present important challenges to species differentiation with remote sensing. The objectives of this paper are as follows: 1) to evaluate the classification performance of a multiple-endmember spectral angle mapper (SAM) classification approach in discriminating ten common African savanna tree species and 2) to compare the results with the traditional SAM classifier based on a single endmember per species. The canopy spectral reflectance of the tree species ( Acacia nigrescens, Combretum apiculatum , Combretum imberbe, Dichrostachys cinerea, Euclea natalensis, Gymnosporia buxifolia, Lonchocarpus capassa, Pterocarpus rotundifolius, Sclerocarya birrea, and Terminalia sericea) was extracted from airborne hyperspectral imagery that was acquired using the Carnegie Airborne Observatory system over Kruger National Park, South Africa, in May 2008. This study highlights three important phenomena: 1) Intraspecies spectral variability affected the discrimination of savanna tree species with the SAM classifier; 2) the effect of intraspecies spectral variability was minimized by adopting the multiple-endmember approach, e.g., the multiple-endmember approach produced a higher overall accuracy (mean of 54.5% for 20 bootstrapped replicates) when compared to the traditional SAM (\mean overall accuracy = 20.5\%); and 3) targeted band selection improved the classification of savanna tree species (the mean overall percent accuracy is 57% for 20 bootstrapped replicates). Higher overall classification accuracies were observed for evergreen trees than for deciduous trees. [ABSTRACT FROM AUTHOR]

In this paper, we describe our approach of using value-sensitive design to guide the design, development, and implementation of health information systems for use in rural areas of two developing countries in Africa. By using shared conceptual investigation, we are able to create a generalized list of stakeholders and values that span multiple projects without losing any of the power of the conceptual investigation. This process can be applied to other projects to develop a stronger set of stakeholders and values. We also present a technical investigation of a vaccine delivery project in Sub-Saharan Africa and plans for an upcoming empirical investigation for a mobile-phone-based support tool for community health workers in East Africa. [ABSTRACT FROM AUTHOR]

The leakage current on heavily polluted silicone rubber insulators is usually smaller than on similarly polluted porcelain insulators. In this paper, results are presented that show that under light contamination, the currents on the two types of insulators can have similar values. Results are also presented from two different sites that show that under certain conditions the currents on silicone insulators can be higher than on porcelain. The phenomenon is explained, referring to the superior washability of the porcelain and moisture absorption of the pollution layer on the silicone rubber insulators during times of high humidity. [ABSTRACT FROM AUTHOR]