Study of Landcover Change in Yelwa-Heipang Area of Plateau State, North-Central Nigeria: A Geoinformatics Approach

This study is a research programme carried out to detect the change in land use/land cover of Yelwa-Heipang area of Plateau State, North Central Nigeria. It lies within the South-Eastern part of the Jos-Plateau. It is about 40 km South of Jos city. It is located between latitude 9°35'16.65" N, longitude 8°52'29.91" E and Latitude 9°38'38.92" N, longitude 8°57'03.87" E (Naraguta topomap, sheet 168S.E). Two sets of Landsat images of 1975, 1986 and NigeriaSat-X image of 2012 were subjected to various image processing techniques and a supervised classification was carried out on the various images using ILWIS (Integrated land and water information system) software. The classification scheme used are bare-surface, built-up, farmland and vegetation. A follow up field work was carried out to confirm the results of the classification. The results were subjected to various statistical analyses and it shows natural vegetated area coverage increased from 5.80 sqkm in 1975 to 18.47 sqkm in 1986 and later reduced to 16.85 sqkm in 2012. Non-vegetated area which comprised built-up area, farmlands and bare surface, decreased from 42.2 sqkm in 1975 to 33.82 sqkm in 1986, then to 35.86 sqkm in 2012.The rate of change of natural vegetation between 1975 and 1986 was 1.152 sqkm per annum, while that of 1986 and 2012 was 0.108 sqkm per annum. Loss of naturally vegetated area in Yelwa-Heipang Barkin-Ladi is mainly as a result of urban growth and expansion, farming and gully erosion. Another important issue in the study area is the problem of soil erosion. In the past mining activity had led to accelerated gully erosion which has stripped substantial areas of lands of their vegetations. This has led to the formation of bare surface. Land cover of the study area during the period between 1975 and 2012 changed from a forested area to other land uses as a result of increase in population, demand for land for agricultural purposes and increase in the demand for firewood

EXPERIMENTAL DESIGN AND DEVELOPMENT OF LOCALLY MADE PARABOLIC TROUGH SOLAR THERMAL COLLECTOR UNIT

The design and analysis of Parabolic Trough Solar Thermal Collector (PTSTC) system used to generate hot/steam water for domestic and industrial purposes were carried out. The parametric studies were also conducted on the collector, study the effectiveness of hot water production for potential applications. The PTSC was designed with Parabolic Software version 2.0. The fabrication and design were done with a combination of reflector surface, reflector support, absorber pipe and wooden stand. The absorber pipe was painted in black colour while the trough was manually operated. The flow of water in the system follows the recycling process repeated during data acquisition. The ambient temperature, the inlet and outlet temperature of the receiver and total solar radiation on the PTSC were recorded. Different flow rate of the Heat Transfer Fluid (HTF) was tested at 0.021, 0.022, 0.023 and 0.024 kg/s respectively. Collected data showed the maximum outlet water temperature attained as 72oC. The average outlet temperature increased from 36oC at 10:30 hour to 69.84oC at 16:00 hour. The average beam radiation during the collection period was 699 W/m2. Different flow rates show that the lower the flow rate, the higher the efficiency of the system. The study revealed that the developed parabolic trough solar collector is viable for the production of sterilized water and low stage steam for domestic and industrial purposes

Crise post-électorale en Côte d’Ivoire et logique de la non-violence en milieu urbain: une illustration à partir des villes de Gagnoa, Guiglo et San Pedro en 2010–11

Les auteurs cherchent à comprendre pourquoi certaines villes clés dans un sens stratégique, symbolique et historique (les villes de Gagnoa, Guiglo et San Pedro) n’ont pas connu de cycle de violence pendant et après la crise post-électorale de 2010 à 2011 en Côte d’Ivoire. Le niveau de motivation de l’armée, des milices des Jeunes Patriotes, et de la population et la cohésion sociale autour des institutions étatiques et traditionnelles locales ainsi que les programmes de solidarité d’ONG locales et internationales permettent de comprendre l’absence de violence dans ces villes. Pour comprendre la logique de la non-violence durant la guerre civile ivoirienne, les auteurs avaient conduit plusieurs interviews semi-structurées à Abidjan, Gagnoa, Guiglo et San Pedro avec des autorités gouvernementales, des organisations internationales, les Jeunes Patriotes, des militaires, des chefs de communautés et des chefs religieux. Ces interviews sont complétées par des études secondaires. This article focuses on western Côte d’Ivoire, which has been the political and military epicentre of the Ivorian crisis since 2000. The authors seek to understand why a number of key cities in a strategic, symbolic and historical sense (the cities of Gagnoa, Guiglo and San Pedro) did not experience a cycle of violence following the post-electoral crisis in 2010 to 2011. Motivation and social cohesion appear as two factors explaining this dynamic of restraint. Methodologically, the article is based on semi-structured interviews with key political and security actors in the three towns and in Abidjan, and completed by secondary sources