Time-Overrun Factors in Nigerian Construction Industry

Factors that affect time overrun in the Nigerian construction industry have been studied, and the rank agreement factor for the professionals are architects∕engineers, 0.75; architects∕builders, 0.83; quantity surveyors∕engineers, 0.74; quantity surveyors∕builders, 0.79; and engineers∕builders, 0.69. Important findings are (1) the degree of occurrence of time overrun is high—between 80 and 90%; (2) relative contributions of the client, contractor, and others are 62, 32, and 6%, respectively; (3) time overrun is more pronounced in government/public sector projects (89%); and (4) time overrun occurs on all projects, irrespective of size.     

A model for transport of hydrogen sulfide in oil- and water-saturated porous media

In several oilfields, reservoir souring by generation of hydrogen sulfide (H₂S) occurs in secondary recovery during which seawater is injected into originally sweet reservoirs. At the production site, high concentrations of H₂S can cause severe damage to both equipment and human personnel. Proper modeling of H₂S concentration in produced fluids can be useful for decision-making during field development design. We present a model for the transport of H₂S in an oil- and water-saturated, water-wet porous medium. The different retardation mechanisms for the H₂S are described. For the adsorption of H₂S to rock, we include two distinct phases of adsorption. In addition, we introduce a functional relationship between adsorption capacity and permeability. As H₂S mixes with oil, fractions become immobile as part of the residual oil.     

Deoxypyridinoline and other biochemical markers of bone resorption in distinct pathologies

Collagen type 1 represents more than 90% of bone matrix. Therefore, quantitation of collagen crosslinks, such as deoxypyridinoline, can provide information on bone resorption degree. An evaluation was made of deoxypyridinoline as well as other bone markets, such as alkaline phosphatase, tartrate resistant acid phosphatase, and hydroxyproline in patients with the diagnosis of osteoporosis. Paget's disease, hyperthyroidism, and chronic renal failure on haemodialysis or not. Deoxypyridinoline levels were significantly increased in patients with osteoporosis, Paget's disease, and hyperthyroidism. Hydroxyproline levels were increased in patients with Paget's disease, and tartrate resistant acid phosphatase was increased in all the entities studied. Deoxypyridinoline can be a more sensitive marker than hydroxyproline, with some advantages, such as its quantitation in a urine specimen and its high bone specificity. In patients with renal failure, tartrate resistant acid phosphatase was the only biochemical marker of bone resorption with increased levels.     

Tyranny of inappropriate policies: Sharing as housing strategy among middle/low income households in Abuja, Nigeria

The housing strategies adopted by urban households in a situation of housing shortage in a particular city will often reflect the peculiar circumstances of that city. This paper investigates one strategy – sharing of dwelling units – adopted by some middle/low income households in Abuja, Nigeria's new capital, in a situation of rapidly increasing population, high cost of living and inadequate housing provision. It is found that a combination of factors – the inability of most Abuja residents to secure residential accommodation from the dominant but limited public sector supply, cultural factors, the housing allowance policy of government and the fact that many relocatees to Abuja do not bring their families – have made a good number of households favourably disposed towards sharing, an option which keeps the amount spent on housing low but which, in most cases, completely excludes personal comfort. It is recommended that, since standard estimates of affordability often provide little guidance to policy makers, the appropriate strategy in search of sustainable solutions would be to make available a range of housing packages from which households in Abuja will choose, and to make adjustments to regulatory regimes so as not to constrain the production of housing.     

Chemical exergy assessment of organic matter in a water flow

In recent years, exergy analysis has been successfully applied to natural resources assessment. The consumption of any natural resource is unavoidably joined to dispersion and degradation. Therefore, exergy analysis can be applied to study the depletion of natural resources and, particularly, to water resources. Different studies range from global fresh water resources evaluation to specific water bodies' detailed analysis.     

The economic unsustainability of the Spanish national hydrological plan

This paper analyses the economic aspects of the Ebro water transfer, which have been overlooked in the Spanish National Hydrological Plan. The questions exam ined are the cost of transferred water, and irrigated agriculture in the Levante and south-eastern regions, which are the main water transfer destinations. Results show that the water transfer is not economically sustainable, because the costs of the diverted water are higher than the current marginal value of water in agriculture, and crop profitability is insufficient to pay for the whole volume of transferred water. A compromise solution between increasing water supply and demand management measures will combine a reasonable water price increase with water desalination in coastal counties. This solution would reduce water demand with a moderate effect on farmers' revenue and net income. Spain could find alternative investment projects to the water transfer, able to improve social welfare.     

Some physical properties and oxidative stability of biodiesel produced from oil seed crops

Biodiesel is a cleaner burning fuel than petrodiesel and a suitable replacement in diesel engine. It is produced from renewable sources such as vegetable oils or animal fats. Biodiesel fuel was prepared from castor (CSO), palm kernel (PKO) and groundnut (GNO) oils through alkali transesterification reaction. The biodiesel produced was characterized as alternative diesel fuel. Fuel properties such as specific gravity, viscosity, calorific (combustion) value, The CSO, PKO and GNO were measured to evaluate the storage/oxidative stability of the oils to compare them with commercial petrodiesel. The biodiesel produced had good fuel properties with respect to ASTM D 6751 and EN 14214 specification standards, except that the kinematic viscosity of castor oil biodiesel was too low. The viscosity of castor oil biodiesel at different temperatures was in the range of 4.12–7.21 mm²/s. However, promising results which conformed to the above specification standards were realized when castor oil biodiesel was blended with commercial petrodiesel. At 28 °C the specific gravity recorded for CSO, PKO and GNO biodiesel was higher than the values obtained for petrodiesel. Commercial petrodiesel had the highest oxidative stability than biodiesel produced from CSO, PKO and GNO oils.     

Evaluation of cooking energy cost,efficiency, impact on air pollution and policy in Nigeria

This study evaluated the cooking energy costs and efficiencies, the air pollution impacts of cooking energy consumption and the impact of the energy policy in the cooking energy sector in Nigeria. Water boiling and cooking experiments using the common cooking energy sources (fuel wood, kerosene, liquefied petroleum gas (LPG) and electricity) and common food items (water, yam and beans) were carried out. Energy surveys were carried out to determine the cooking energy use patterns in the urban and rural areas. It was found that fuel wood is the least expensive cooking energy source and LPG is the most expensive. Energy use efficiencies for boiling water were estimated at 25%, 46%, 73%, 79%, 66% and 90% for fuel wood, kerosene, gas, electric immersion coil, electric heating coil and electric hot plate, respectively. Energy intensity was found to be a comparative measure of energy efficiency. The impacts of air pollution from household cooking suggested a possibility of significant air pollutants contribution to the ambient environment using any of the energy carriers considered except electricity. The cooking energy use patterns showed that fuel wood is the predominant energy source for cooking in the rural areas while kerosene is the predominant energy source in the urban areas, revealing that the energy policy in the country had made no impact in the cooking energy sector. Recommendations for improving the energy supply situation were given and for removing the barriers that prevent the implementation of the recommendations.     

Nanocrystalline Fe1−xCoxSn2 solid solutions prepared by reduction of salts in tetraethylene glycol

In an effort to improve the electrochemical performance of tin intermetallic phases as electrode active material for lithium-ion batteries, Fe_1−xCo_xSn₂ solid solutions with x = 0.0, 0.25, 0.3, 0.5, 0.6 and 0.8 were prepared by chemical reduction in tetraethylene glycol. Precise control of the synthesis conditions allowed single-phase nanocrystalline materials to be prepared, with particle diameters of about 20 nm and cubic, nanorods, and U-shaped morphologies. The substitution of iron by cobalt induced a contraction of the unit cell volume. The hyperfine parameters of the ⁵⁷Fe Mössbauer spectra were sensitive to the Co/Fe substitution and revealed a superparamagnetic behaviour. In lithium cells nanocrystalline Fe_1−xCo_xSn₂ active materials delivered reversible capacities above 500 mAh g⁻¹ that depended on the composition and cycling conditions. The intermediate compositions exhibit better electrochemical performance than the end compositions CoSn₂ and FeSn₂.     

Mixture temperature prediction of waxy oil–water two-phase system flowing near wax appearance temperature

Temperature sensitivity of waxy crude oils makes it difficult to study their flow behaviour in the presence of water especially near their wax appearance temperature(WAT). In this study a method was proposed and implemented to mitigate such difficulties which was applied in predicting mixture temperatures(Tm) of a typical Malaysian waxy crude oil and water flow in a horizontal pipe. To this end, two analytical models were derived firstly from calorimetry equation which based on developed two correlations for defining crude oil heat capacity actualized from the existed specific heat capacities of crude oils. The models were then applied for a set of experiments to reach the defined three predetermined Tm(26 °C, 28 °C and 30 °C). The comparison between the predicted mixture temperatures(Tm,1and Tm,2) from the two models and the experimental results displayed acceptable absolute average errors(0.80%, 0.62%, 0.53% for model 1; 0.74%, 0.54%, 0.52% for model 2). Moreover,the average errors for both models are in the range of standard error limits(±0.75%) according to ASTM E230.Conclusively, the proposed model showed the ease of obtaining mixture temperatures close to WAT as predetermined with accuracy of ± 0.5 °C approximately for over 84% of the examined cases. The method is seen as a practical reference point to further study the flow behaviour of waxy crudes in oil–water two-phase flow system near sensitive temperatures.