Volume XI Issue II

Naval architect and marine hydrodynamist also seek to understand the motion response of floating structure and many approaches have been employed as well. One of such analysis is the spectral analysis of any mode of the vessel response. In this paper, the response spectral analysis of a heaving semi-submersible with two cylindrical pontoon and four columns and six columns will be examined. The analysis was carried out with the irregular sea modelled using the JONSWAP spectrum and it was seen that the area under the motion spectrum was narrow band as expected with a broadness parameter of 0.15 seconds and fourth spectral moments of the displacement response spectrum of the heave mode were also computed and agreed with the Rayleigh distributions model.

Sri Lanka has undergone numerous changes in the fields of social-economic and cultural processors during the past decades. Consequently, the Sri Lankan construction industry was subjected to rapid growth while contributing a considerable amount to the national economy. The prevailing situation under the Covid-19 pandemic exhibited challenges to almost all of the sectors of the country in attaining success. Although productivity is one of the dimensions that measure the degree of project success, achieving sufficient productivity has become challengeable due to the Covid-19 outbreak. As employee motivation is an influential factor in defining productivity, the present study becomes significant in discovering ways of enhancing construction productivity via employee motivation. The study has adopted a combination of qualitative and quantitative methodologies in attaining the study objectives. While the research population refers to construction professionals in Sri Lanka, the study sample is aimed at Quantity Surveyors in the bottom and middle managements of organizational hierarchies. The data collection was implemented via primary and secondary sources. The primary data collection was accomplished by undertaking semi-structured interviews and online questionnaire surveys while sampling the overall respondents based on the purposive sample method. The responses of the questionnaire survey were gathered in a form of a ‘Likert Scale’ to examine the degree of applicability on each respondent. Overall, 76.36% of primary data were recovered from the expected count while obtaining 60 responses from the questionnaire survey and 24 responses from interviews. Secondary data were obtained by reviewing sources such as research articles, journals, newspapers, books, etc. The findings suggest adopting and enhancing sixteen motivational factors in achieving greater productivity in the Sri Lankan construction sector.

Fabrication of steel structures such as car bodies, shafts and pressure vessels always involves shaping and surface strengthening (case hardening of the metal). Shaping operations such as bending, drawing and twisting strain hardens the metal as well as the carburizing process. Therefore the strength of the metal required at different stages of metal forming process depends on the operations needed at each stage. Thus, this paper is a presentation of effort made to determine the combined effect of strain hardening and carburizing on the some mechanical properties of plain carbon steel. In this study, seven pieces of tensile test specimens were produced from 0.21 weight percent carbon steel. The gauge length of the specimens was 50mm while the cross-sectional diameter was 10mm, which is in accordance to British Standard Specification. Six pieces of the specimens were carburized using a homogeneous mixture of pulverized charcoal, calcium carbonate and barium carbonate in 70 %( 10.5kg), 20 %( 3kg) and 10 %( 1.5kg) proportions respectively as source of carbon and XKL15 laboratory furnace for heat treatment. The mixture (carbon source) was put into a 12litres steel box and six specimens were buried in the carbon base medium, maintaining uniform spacing of 5cm and was well compacted. Together with its content, the steel box was then put in the furnace and the furnace was then powered and regulated to 950oC. All through the heat treatment time, the furnace was maintained at constant temperature of 950oC (Holding Temperature). One specimen was withdrawn from the furnace at 4 hours intervals; thus, the specimens were carburized 4, 8.12,16,20 and 24 hours soaking times and cooled naturally under atmospheric pressure. They were cleaned and tested together with the non- heat treated specimen using Admet Tensile Test Machine. From the stress-strain curve obtained in each case, stress values at 0.02 strain intervals were deduced. The ultimate tensile stress of each specimen was also determined and recorded. The values obtained were represented graphically and also used to determine the strain hardening coefficient of each specimen, using Least Square Method. The length of each specimen at fracture was also measured using Mitutoyo 500-196-30 digital caliper and the values obtained were used to calculate the percentage elongation. From the results obtained, the strain hardening coefficients are 0.2656, 0.3003, 0.3436, 0.3668, 0.3814, 0.3988 and 0.4141 for the untreated specimen, 4, 8.12,16,20 and 24 hours heat treated specimens respectively. Also, the percentage elongation are 22.00, 18.00, 16.00, 14.10, 13.89, 12.00 and 10.00 for the untreated specimen, 4, 8.12,16,20 and 24 hours heat treated specimens respectively. The ultimate tensile stress are 296.99, 348.07, 370.43, 385.42, 409, 415.48 and 420.82MPa for the untreated specimen, 4, 8.12,16,20 and 24 hours carburized specimens respectively. The results obtained show that strain hardening coefficient and tensile strength of the steel increase with increase in soaking time so also the tensile strength of the steel. On the other hand , the ductility(percentage elongation) decreases with increase in soaking time until it drops to its least and constant value .The results of this study may serve as a guide in controlling of the strain hardening of plain carbon steel in advanced metal processing which is applicable in general metal fabrication. A further study is recommended in which the carburized case depth for each soaking time is determined. It will also be of interest to determine variation of the mechanical properties of the steel with the carburized case depths. The results of this study would be instrumental in predicting the overall quality a finished product in metal forming process.

With Nigeria’s large and growing population, and rapid growth in urbanization, there is the likelihood that the energy demand including that for transportation will continue to increase and, thus, put further pressure on the country's environment, intensify the climate change threat and exacerbate transportation energy challenges. This study critically evaluated Autogas and CNG, and the factors impeding its utilization in Nigeria. The study also discussed other gas utilization options. Technological modifications needed to boost the utilization of CNG as a transportation energy source were discussed. Finally, a comparative analysis of Autogas, CNG, natural gas to hydrogen and natural gas to electricity technologies in transportation sector was conducted using Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). From the TOPSIS analysis and results, the best natural gas transport technology considering fuel life cycle efficiency and life cycle greenhouse gas emission is Natural Gas to Electricity technology with a score of 0.691. This is followed by Natural gas to hydrogen technology with a score of 0.689. This is followed by LPG with the score of 0.459. CNG is the least efficient technology in this analysis with a score of 0.308. The TOPSIS analysis indicated that Autogas and CNG is superior to the other transport fuel technologies in terms of greenhouse gas emissions but performed poorly against them in the area of fuel life cycle efficiency. Hence, more focused researches on how to improve the fuel life cycle efficiency of CNG in order to maximize its utilization in the transportation sector and boost the Nigerian Economy need to be conducted.

The microbial analysis of flood waters was investigated in Tombia community, Yenagoa, Bayelsa state, Nigeria. This was done to determine the type of microbes associated with flood water in Tombia community and the potential health risk implications of flood waters. Triplicate water samples were collected with sterile bottles from four different locations at Tombia community. Samples were tested using standard procedures and techniques. Result from the investigation reveal that all the samples that were collected from four sampling stations had bacteria and fungi. The total heterotrophic count ranged from 1.80 x 106 - 7.10 x 106 cfu/ml. Location 4 has the lowest heterotrophic count while Location 2 had the highest heterotrophic count. In this study the coliform and lactose enteric fermenting bacterial count ranged from 1.81 x 104 - 3.53 x 104 cfu/ml. Location 3 had the lowest count while Location 1 had the highest count. The total fungi count ranged from 1.56 x 105 - 8.67 x 105 cfu/ml. Location 1 had the lowest count while Location 4 had the highest count. The results show a total of 10 different bacteria isolates. However, they occurred differently in terms of the frequency of isolation. With E. coli and Enterobacter occurring in every sample tested. The characterization of fungi isolate associated with the four different stations shows a total of 4 different fungi isolate. However, they occurred differently in terms of frequency of isolation, with Fisarium and Mucur species occurring the most. The general picture of flood water microbial analysis in this study, showed that the flood water samples collected from the four different locations in Tombia community were all contaminated with all sorts of bacteria and fungi. As flooding in low land areas is a perennial event, it is important that more data on pathogen concentration in flood waters should be collected to make more reliable health risk assessment, because of the health risk associated with flood incidents are expected to increase in the future, due to more rainfall induced by climate change.