ARID ZONE JOURNAL OF ENGINEERING, TECHNOLOGY AND ENVIRONMENT

13-23

Authors: B S Waziri, A T Jibrin, B Kadai

Construction duration significantly influences funding, financing and resources allocation decisions that take place early in project design development. This study attempts to develop through regression analysis highway construction duration models by incorporating relevant predictor variables having statistically significant relationship with highway completion time. Historical data of highway projects initiated and completed between 2007 and 2012 were considered to enable the collection of homogenous data in terms of time, cost and other economic variables. Three multiple regression models were developed in the form of linear, semi-log and log-log transformations. The performances of the models were established by measuring their prediction accuracy and goodness of fit over a test sample of 15 successful projects. Results of the analysis showed that all the three models are statistically significant and have good fit to the data with R2 values of 0.816, 0.877 and 0.970 respectively. The log-log model outperformed the other models with an average percentage error of -2.94%, maximum error of 15.5% and mean absolute percent error (MAPE) of 6.95%. The compare favourably with past studies which have shown that traditional methods of duration estimation at early project stages have values of MAPE typically in the order 10-20%.

41-52

Authors: M Abdulsalam, M Isiaka, M A Gwarzo, M K Dalhat, I B Dalha

Suitable field workdays for agricultural machine operations (ploughing, harrowing and ridging) of some selected areas of Kaduna State in Nigeria were determined using soil moisture level and rainfall criteria. These involved the development of soil moisture budget and establishment of tractability criteria for each soil types assessed. Thirty (30) years meteorological information of these areas were collected from the Institute for Agricultural Research ABU, Zaria and total of 200 soil samples were collected from 20 different farm lands and analyzed. The soil particle sizes, bulk densities, soil moistures level at field capacity and plastic limits were determined and the soil moisture limits were used to set the tractability criteria for each soil types. The information obtained was used to develop a computer based programme to monitor the variation in the moisture level. The estimated soil moisture levels and rainfall amount were compared with the tractability criteria to segregate the tractable and non-tractable soil moisture determining suitable and non-suitable workdays respectively. Out of the annual crop growing season of 214 days (from April to October) considered in this study, the sandy-clay-loam soils had the highest machinery suitable field workdays of 76 (35.51%) days for tillage operations (ploughing, harrowing and ridging). The clay soil had the least available machinery tillage workdays of 49 (23.00%) days. The sandy, sandy-loam, loam and clay-loam soils have 69 (32.24%), 63 (29.44%), 54 (25.23%) and 50 (23.36%) suitable workdays respectively.

63-74

Authors: I S Mohammed, A A Balami, M Abdullahi, S M Dauda, M Aliyu

The rising cost of traditional stabilising agents and the need for economical utilisation of industrial and agricultural waste for beneficial engineering purposes has encouraged an investigation into the stabilization of clay soil with lime and melon husk ash. The chemical composition of the melon husk ash that was used in stabilising clay soil was determined. The clay soil was divided into two parts, one part was used to determine the index properties while the other part was treated at British Standard Light (BSL) compaction energy with 0 %, 2 %, 4 %, 6 % and 8 % melon husk ash by dry weight of the soil and each was admixed with 2 %, 4 %, 6 % and 8 % lime. The stabilised clay soil was cured for 7, 14 and 28 days before the unconfined compressive strength were determined while the coefficients of permeability of the stabilised clay soil were also determined at 28 days of curing. The data obtained from the experiment was subjected to analysis of variance to examine the significance at 5% level. Results showed that the natural clay soil belong to A-7-6 or CH (clay of high plasticity) in the American Association of State Highway Transportation Official (AASHTO) and Unified Soil Classification System (1986). The chemical composition of the ash had aluminum oxide, iron oxide and silicon dioxide values of 18.5%, 2.82% and 51.24% respectively. The unconfined compressive strength and coefficient of permeability of the natural clay soil was determined to be 285 kN/m2 and 1.45 x 10-5 cm/s, respectively. Increase in melon husk ash and lime percent increases the unconfined compressive strength (UCS) of the stabilised clay soil significantly (p < 0.05) and decrease the coefficient of permeability when compared with the natural clay soil. The peak values of unconfined compressive strength for 7, 14 and 28 days of curing are 1200 kN/m2, 1598 kN/m2 and 1695 kN/m2 respectively at 6% MHA and 8% lime content while the lowest value for coefficient of permeability was 0.98 x 10-6 cm/s at 6% MHA and 8% lime. These results indicate that 6% MHA can be used to increase UCS and reduce permeability of the clay soil.

85-93

Authors: A H Alkali

Segmentation is employed in everyday image processing, in order to remove unwanted objects present in the image. There are scenarios where segmentation alone does not do the intended job automatically. In such cases, subjective means are required to eliminate the remnants which are time consuming especially when multiple images are involved. It is also not feasible when real-time applications are involved. This is even compounded when thermal imaging is involved as both foreground and background objects can have similar thermal distribution, thus making it impossible for straight segmentation to distinguish between the two. In this study, a real-time Iterative Elimination Algorithm (IEA) was developed and it was shown that false foreground was removed in thermal images where segmentation failed to do so. The algorithm was tested on thermal images that were segmented using the inter-variance thresholding. The thermal images contained human subjects as foreground with some background objects having similar thermal distribution as the subject. Informed consent was obtained from the subject that voluntarily took part in the study. The IEA was only tested on thermal images and failed when false background object was connected to the foreground after segmentation.

103-116

Authors: O A Bamgbade, T E Omoniyi, T A Ewemoje

The gate-to-gate study aimed to evaluate the potential environmental impacts associated with the production of vegetable oil and to proffer ways of improving and reducing some of the environmental impacts associated with the production system. This study compared the Life Cycle Impact Assessment (LCIA) of four scenarios; different transportation distances for palm kernel materials and different type of fuel used in the boiler. The LCIA was conducted using Gabi 6 and Tool for the Reduction and Assessment of Chemical and other Environmental Impacts (TRACI) methodology. Overall energy consumption in the crushing plant was 34,647.77 MJ and energy consumption in the refining plant was 23,371.65 MJ. Global Warming Potential (GWP) was from 0.0771 kg CO2-equiv., to 0.0763 kg CO2- equiv. for all scenarios. Acidification Potential (AP) values for the four scenarios were: 0.0493 kg H+, 0.0478 kg H+, 0.0476 kg H+ and 0.0492 kg H+ moles-equiv. Eutrophication Potentials (EP), were 6.796E-5 kg N-, 4.88E-5 N-,6.726E-5 N- and 4.905E-5 N-equiv. for scenarios 1, 2, 3 and 4 respectively. Energy is consumed and expended more in the crushing plant than in the refinery plant. The best environment viable for vegetable oil production is to have a short distance as possible for raw materials and the use of diesel oil for firing boilers (scenario 2) as compared with Low Pour Fuel Oil (LPFO). It was recommended that study on environmental performance of vegetable oil production from different oil sources should be investigated in Nigeria, from cradle to grave.