Journal of Civil and Environmental Engineering

The quality of road infrastructure is dependent on many factors including materials used and contractor competency in terms of managing the project and the team. Poor workmanship has been mostly blamed on these factors. Kenya and Africa at large has realized the road to grow economy is through infrastructural development projects hence investing billions of money into this noble course. Although many studies have been conducted on road construction, the focus is always drawn on the implementation phase thereby forgetting the post-delivery phase. The study aimed to assess the moderating influence of process monitoring on the relationship between contractors’ capacity evaluation in tender award and performance of road construction infrastructural project in the context of Nairobi county, Kenya. The study used both a cross-sectional descriptive survey research design and correlation research design. A sample size of 210 was obtained from a target population of 460 comprising of 106 contractors and 104 Public Service Vehicles (PSVs) drivers. Stratified sampling and proportionate sampling were used to arrive at the right sample size. Simple random sampling helped in distribution of research instruments. Pilot test was done to ensure validity and reliability of research instruments is achieved. Validity of instruments was done by use of content validity to ensure research questions aided in achieving research objective. To maintain reliability of data, Cronbach alpha values of above 0.7 were deemed important. Questionnaires were administered to contractors registered by National Construction Authority of Kenya whereas structured interview schedules were distributed to the drivers in Nairobi County. In total, 153(72.8%) of response rate was recorded. Quantitative data was descriptively analyzed whereby measure of central tendency and dispersion was done through means and standard deviation. Karl Pearson Correlation Coefficient was used to show relationship between variables under the study. Hypothesis was tested by use of Analysis of Variance (ANOVA) whereby multiple regression and hierarchical analysis were conducted to explain the direction, the strength and the nature of relationship between the study variables. The results showed that in both step one and two, F-values were statistically significant. That in step one R=0.826, adjusted R2=0.673, F(4,148)=79.226, p=0.000<0.05 and in step two: R=0.837, adjusted R2=0.690, F(5,147)=68.520, p=0.000<0.05. This implies that contractors’ capacity evaluation in tender award alone explains 67.3% of variation in road performance. However when put together with process monitoring they explain 69.0% of total variation in road performance. Thus the null hypothesis was rejected and alternate hypothesis accepted that process monitoring significantly moderates the relationship between combined factors of contractors’ capacity evaluation in tender award and performance of road construction infrastructural projects. The study concludes that process monitoring indeed moderates contractors’ capacity to carry out construction work and hence road performance. The study further recommends that future road construction should aim to incorporate process monitoring in its operations to ensure that the right inputs or resources are utilized to yield quality outputs and that the required standards, policies and laws are adhered to.

In the vacuum, some solids could be used as gas filters not only through the empty spaces of the crystal lattice but also through the electronic clouds of the atoms that make up the solid. With the use of particular equipment in the vacuum we could obtain a new energy, look for the energy sufficient for the adaptability of the electronic cloud and obtain a suitable temperature for the adaptability of the electronic cloud. In the case suppose that the electronic clouds of the atoms constituting the solid are valued by the ions, this energy is subtracted from ion ionization energy in the total energy of the molecules distribution and, through some mathematical passages, we deduce a temperature sufficient for the passageway of the electronic cloud suitable for some solids. An ion and/or an atom to be filtered should have a smaller diameter than the atomic radius of the atom that constitutes the filter, for the transition through the electronic clouds. The gases could cross the solid or in the empty spaces of the crystal lattice or in the electronic clouds of the atoms that make up the solid due to the difference between the force fields. In this way, during the passage the atoms and/or the ions composing the gas do not incorporate the nuclei of the atoms constituting the solid and avoid potential highs including the Yukawa potential. Possible future applications could improve the quality of life, in particular it would be possible to reduce atmospheric pollution by making molecular hydrogen.

Ensuring water security to urban population in fragile environments through interlinked systems of groundwater abstraction, storage and distribution of sufficient quantity is challenging especially to urban utilities situated in arid and semi arid regions. The purpose of this research was to evaluate water delivery challenges for water utilities in fragile environment in Kenya. A systematic analysis of availability from each supply sub-components from source to consumer was carried out through water audit and network analysis by employing water flow measurement equipments and through pump performance analysis and by employing continuity equation and Bernoulli’s principle to sections of the network. Results showed that water availability within a utility in such environments is contributed by seasonal variations between wet and dry affecting quantity at source, optimal design of supply infrastructure in this case better matching of solar power with the pump, using standard pipes and on optimal operational strategies employed to reduce losses within the network. Based on these findings, we conclude that with clear understanding of each subcomponent’s contributions to entire water supply system and optimizing their design and operations, more people will be made water secure in all seasons in the fragile environments.      

The quality and accessibility of drinking water is chief importance to human health. The main objective of this work was to use Moringa oleifera seeds as a natural coagulant in electrocoagulation process for the treatment of electroplating industry wastewater. It has been found that Moringa oleifera is the best bio coagulant which can replace aluminum sulphate (alum). The efficiency of Moringa oleifera seed cake in removing heavy metals ions such as chromium, copper, zinc, cobalt and lead from the wastewater sample by means of jar test followed by electrocoagulation process was very much reliable. The removal of heavy metal ions observed for Moringa oleifera seeds treated water were 79% for lead, 50% for copper and zinc, and more than 90% for chromium and cobalt, at an optimal dosage of 200 mg/L. Around 90-96% of turbidity has been reduced from the wastewater by Moringa oleifera seed cake, though it has a no glaring effect on the pH which is also an advantage. The Moringa oleifera seed treated water has been taken for the further treatment by electrocoagulation process. Concluding that, the rate of removal of pollutants linearly increased with increasing doses of seed cake. During electrocoagulation process the heavy metals like cobalt and lead was completely removed from the water sample and other heavy metal ions such as chromium, copper and zinc concentration in water sample has met the level of water standards of WHO (World Health Organization).