Floods are the most common and widespread climate-related hazard in the Lake Victoria region. However, significant delays in ground data availability have made it unfeasible to use traditional flood forecasting systems. Satellite rainfall estimates have been identified as readily and economically available data that can be used as input to run hydrologic models and produce flood-warning systems. The aim of the study therefore is develop a simple and locally viable alternative approach to circumvent the absence of reliable ground measurements by using satellite rainfall estimates for forecasting and management of floods in the study area. The satellite-derived rainfall estimates (RFE) were first evaluated using historical rainfall data for the Nyando basin corresponding to the locations of 35 gauging stations in the basin for the period 1995 to 2005. A Digital Elevation Model (DEM) of the basin was used to generate the drainage patterns of the basin. The land cover of the study area and the digital soil map are incorporated in the system. The study applies daily driven satellite-derived rainfall and the pixel based Curve Number method for spatially distributed hydrologic streamflow modelling and flood forecasting. Rainfall–runoff relationships results of the area obtained in a spatial scale are then tested on their capabilities as a flood early-warning system by comparing them with historical streamflow. The approach was further tested using RFE for the period 2006 to 2012. The results for comparisons at daily accumulations of RFE with observed rain gauge data are not satisfactory but they performed reasonably well in detecting the occurrence of rainfall. The products show significant results for 10-day accumulation where regression analysis yielded on average, a correlation coefficient (r) of 0.78. While graphical plots of daily-observed stream flow against simulated streamflow show a poor agreement.

Use of botanical environmentally friendly and biodegradable insect repellents as opposed to chemical insecticides is increasingly becoming important as an alternative method of insect control. Housefly (Musca domestica L.) has potential of transmitting pathogen which causes diseases such as parasitic worms, anthrax, tuberculosis, bacillary dysentery, cholera and typhoid. Human diseases can be treated and prevented by essential oils with biological properties which have been derived from aromatic plants. In this study antimicrobial activities and housefly repellence of P. citrosum and R. officinalis was evaluated separately and in products formulated from the extracts. Extraction of essential oils was by hydro-distillation. Condensed oil extracts were collected in n-hexane and insect behavioural response tested using adult houseflies (Musca domestica L.). N,N-diethyl-m-toluamide (DEET) acted as the positive control with acetone acting as the negative control. The bioactive oil was then analysed using GC-MS. The characteristic volatiles obtained from the two oils showed different compositions. P. citrosum oil comprised mainly of linalool, geraniol, m-camphorene, 2-naphthalenemethanol-1,2,3,4,4a,5,6,7-octahydroalpha, geranylangelate while R. officinalis comprised mainly of α-Pinene, Eucalyptol, α-Terpinenol. Dose-response evaluations of these oils showed that R. officinalis oil (LD50 = 0.299 mg) was more repellent than that of P. citrosum (LD50 = 0.445 mg). The Disk diffusion method was used to carry out the antimicrobial activities of the R. officinallis and P. citrosum. The outcomes showed that the P. citrosum essential oils had antimicrobial activity against Candida albicans, Escherichia coli and Bacillus subtilis at a low concentration of 0.5 % v/v and that the activity was concentration dependent. R. officinalis essential oils, on the other hand, exhibited active antimicrobial properties against Candida albicans, Staphylococcus aureus, Escherichia coli and Pseudomonus aeruginosa. The study showed that P. citrosum was more effective than gentamicin and nitrofuractoin drugs against Staphylococcus aureus at a higher concentration of 6 % v/v. Oil extracts from R. officinalis also illustrated similar trends and were similar to the positive controls against the tested microbes. These results provide scientific justification for traditional use of R. officinalis oil and Pelargonium citrosum essential oils for the control of housefly and other common insects in the household

Harmonic distortions for low voltage distribution network is a research area that has not been extensively explored due to the assumption that the harmonics do not adversely affect low voltage equipment. However, field data collected shows contrarily that current harmonic generated by nonlinear residential customer loads do immensely affect distribution transformers by causing speedy deterioration of the transformers insulation. In the past few decades, there have been considerable changes on residential single phase loads in terms of power demand magnitude and appliance electrical characteristics. The main difference between the current residential single phase loads and earlier versions of a few decades ago is widespread use of electronic appliances with Switch Mode Power Supply (SMPS). These loads are rapidly increasing due to advancement of technology in semi-conductor devices and digital controllers. Such appliances generate current harmonic distortions, which stream back to the low voltage distribution network affecting installed low voltage network equipment. The adverse impact of the generated harmonic distortions are witnessed in premature failure of distribution transformers, erroneous recording of energy meters and over-loading of neutral conductors to mention just a few. This study focuses on analysis and mitigation of current harmonics distortions on distribution network. It involved measurement of current harmonics generated by domestic consumers individual appliance and combined appliances at Point of Common Coupling (PCC) and current harmonics streaming at the secondary side of distribution transformers. Transformers’ oil breakdown voltage was analyzed from sampled transformers to correlate between harmonics and degradation of the oil insulation level. The failed transformers for a period of one year in one of the region was obtained and analyzed. Based on the results of the analysis that show high harmonic pollution on low voltage distribution network, a mitigation measure was devised that involved design and simulation of a single phase active filter using MATLAB–Simulink software. From this work, it was found out that loads with similar electrical characteristics aggravate harmonics and loads with dissimilar electrical characteristics attenuate harmonics. Further, the high current harmonics cause speedy degradation of transformer liquid (oil) insulation and lastly the high current harmonics observed at domestic consumers PCC emanating from current domestic appliances can be mitigated by employing a single phase shunt active filter. The designed and simulated single phase active filter, in MATLAB/Simulink environment, the distorted current waveform was noted to be sinusoidal (undistorted) after introduction of single phase shunt AHF and the current harmonic distortion levels obtained were well within the admissible level recommended by IEEE 519-1992, a power quality standard

Rapid urbanization and global warming have led to the Urban Heat Island (UHI) phenomenon in Nairobi City. The UHI phenomenon is considered the most interpretive indication of an urban climate change in the current time of increasing urbanisation. Proper climate change adaptation planning actions in Nairobi city require recognizing the possible range of UHI intensity and spatial dispersion. However, climate research and its applications in urban planning and improvement in Nairobi city is constrained by inadequate evaluation and irregular descriptions of the local city's characteristics. Therefore, there is a need to study the correlation between urbanisation and UHI and quantify the benefits of plant species on microclimate and human thermal comfort within Nairobi city. The study models and simulates the UHI of Nairobi and further quantifies environmental amelioration effect of different tree species on microclimate and human thermal comfort in the city. The city was first classified into Local Climate Zones (LCZs), then estimated the land surface temperature (LSTs) distribution using a split-window algorithm, and simulated 2m air temperature by MUKLIMO_3 model to show UHI phenomenon for Nairobi city. After that, the attenuation effects of selected plant species on microclimate and human thermal comfort were quantified. The study generated the current LCZ classification for Nairobi city. Both built-up (LCZ 1-10) and natural (LCZ A-G) areas are present. The LCZ classification captured the forms and functions of each zone and indicated the potential UHI distribution pattern of Nairobi city. The study confirmed the presence of urban heat loads in built-up areas with a high percentage of water-resistant, non-reflective surfaces and low vegetation compared to the surrounding rural areas. Statistical analysis of LSTs showed significant differences among typical LCZs. Additionally, the amelioration effects of selected individual plant species demonstrated differences in performance. Focus benjamina (vast dense canopy) presented the highest ability to attenuate environmental parameters (surface temperature, ambient temperature globe temperature, and relative humidity) and reduce thermal discomfort index, followed by Cassia spectabilis, Warburgia ugandensis, Ficus religiosa, Callistemon citrinus followed by Dypsis decaryi, Bambusa vulgaris, Terminalia mantaly and Schinus molle (small open canopy). In conclusion, the study presented the LCZ Nairobi as a basic spatial unit for synoptic characterization and comprehensive climate-based classification of the city sites for urban planning and management. The spatial pattern of urban heat loads in Nairobi is influenced by local climate formation as differentiated by urban form (urban morphological parameters) and functions. In addition, the attenuation effects of plant species in urban spaces vary based on their allometric properties and planting designs. Therefore, proposals for urban planning and design strategies to manage urban heat in Nairobi City can optimize the form and layout of urban LCZs to enhance ventilation and promote appropriate building

A Recirculating Aquaculture System (RAS) attempts to provide sustainable utilization of the available water resources by reducing water pollution and water acquisition costs. Improper matching of RAS components yields inflated cost of production and consequently leads to system failure. The significant challenges in RAS are to maintain favorable water quality for the fish and create conducive conditions that minimize the cost of energy required. In Kenya, many Recirculating Aquaculture Systems have not been able to strike a balance between the optimal levels of water parameters and the cost of energy required to run the system. This study, therefore, aimed at evaluating environmental and energy requirements for different production densities of Nile tilapia (Oreochromis niloticus) in a RAS. In this study, both production density and water flow rates were varied, and water quality parameters namely Dissolved oxygen, ammonia, pH, EC, and temperature monitored. Tilapia stocking densities were varied between 2.3 kg/m3 and 10 kg/m3 while flow rate was varied from 2.0 L/min and increased at intervals of 1 L/min to a flow rate of 10 L/min. The energy consumed for the different stocking densities and flow rates was also monitored using installed electricity meters.

In Blind Source Separation (BSS) the challenge is to recover the source signals from the observed mixed signals. Blindness means that neither the sources nor the mixing system are known. Separation can be based on the theoretically limiting but practically feasible assumption that the sources are statistically independent. The statistical independence of source signals assumption connects BSS and Independent Component Analysis (ICA). The main aim of this research is to solve the separation problem for source signals and mixing system that are not known by comparing two activation functions. The research uses the Natural Gradient Algorithm (NGA) to separate pairs of sub-Gaussian (music), super-Gaussian (speech) and sub-superGaussian mixed signals into their original components using Independent Component Analysis (ICA) assumption of statistical independence of the source signals. Two activation functions are used within the NGA for each of the pairs before separation comparison is made. The NGA is formulated using instantaneous Blind Signal Processing where time delay is not factored in the computation of the independent signals. The design uses a 2 x 2 Multiple Input Multiple Output (MIMO) system to accept the pairs of blind audio signals, mix them and separate them to retain their original form or their filtered version. The Fibonacci activation function and the Sigmoid activation functions are used in iterating the coefficients of the NGA up to a hundred iterations where convergence is realized. Comparing the output (estimated) to the input signals is by waveforms, frequency spectra, and the measure of the Magnitude-Squared Coherence. The results show that the NGA algorithm with Fibonacci and Sigmoid

Present infiltration of substandard steel reinforcing bars on local market have had a serious concern and suspicion on strength and stability of buildings and other engineering structures that are being built with them. Some buildings have collapsed while others have developed signs of structural failures setting huge number of users into serious fears with subsequent vacation. Besides the failures in Rwanda, there has been disastrous incidences of collapsing buildings in neighboring countries where most of rebars are imported from and investigations have pinpointed substandard steel reinforcing bars. Primary objective of this study was to investigate the quality of steel reinforcing bars available in Rwanda and their performance on structural elements specifically reinforced concrete beams flexural behavior. So far only one research is known to have investigated quality of steel bars available in Rwanda with much focus on steel bars milled from scraps of which the results were equally disappointing. In this research 24 samples of steel reinforcing bars of 12mm and 10 mm ϴ from four different sources available in Rwanda were randomly picked from warehouses. Each source were represented by six specimens, three of which were 12mm ϴ and the other three of 10 mm ϴ. Samples were assessed for their physical features compliance, mechanical and chemical properties were examined and finally RC beam flexural performance behavior investigated through laboratory tests. Results obtained showed that rebars physical feature standard code requirements were not met by 75%, while 48.5% of tested samples failed to meet high yield strength BS and RS EAS code prescription of 460N/mm2 only meeting mild steel bars limits. Of the failed 48.5% only 12.5% were Y12mm while the remaining 87.5% were Y10mm. The ultimate load of RC beams made of Y12 mm were determined to be in range of 114.6 KN to 142.6 KN while their respective flexural strength ranged from 25.7 N/mm2 to 33.4 N/mm2 as compared to design load of 111.8 KN and design flexural strength of 25.1 N/mm2 respectively. The flexural load of RC beam made of Y10 mm was found to be in range of 93 KN to 131.5 KN while their respective flexural strength ranged from 20.89N/mm2 to 32 N/mm2 as compared to design load of 78.2 KN and design flexural strength of 17.6 N/mm2 respectively. It is revealed from research that substandard rebars are still at large but more so with rebars that were not labelled at all which failed at 100%, all sample from S3 were not labelled at all for both Y12mm and Y10mm and failed to meet code requirements. Keywords:

Disputes have become a common problem afflicting the construction industry and they have the tendency to cause undesirable effects if not effectively resolved. Such effective resolution requires timely and economical resolution, with final outcomes that are satisfactory to the disputants involved. Arbitration has for a while been the preferred resolution method. However, it has recently been the subject of discussion both in industry and academia because of incessant delays, high costs and increasingly unacceptable awards. Although studies have attempted to identify the various causes of ineffective arbitration, they have not only been descriptive but also relied on anecdotes and subjective opinions. Consequently, the studies’ findings have little explanatory power, making it difficult to confront the underlying causes of arbitral ineffectiveness. The aim of this comparative case study was to develop a framework for effective arbitration of construction disputes in Kenya. A review of the related literature brought out ten determinants of arbitral effectiveness, including award favourability, perceived award fairness, perceived procedural fairness, perceived quality of the decision-making process, perceived quality of treatment, perceived adequacy of the size of the tribunal, approaches to the presentation of evidence, competence of the tribunal, distribution of control and complexity of the dispute. These factors were conceptualised into a structural model. Qualitative data collection and analysis were then undertaken to establish the relationships among the factors. Thirteen semi-structured interviews of participants in five construction disputes in Kenya helped to explain the factors influencing the effectiveness of construction arbitration, which formed the basis upon which the framework was developed. Pattern-matching analysis helped to reveal that out of the ten identified factors, only award favourability was found to directly influence arbitral effectiveness. Four other factors including the approaches to the presentation of evidence, the competence of the tribunal, distribution of control and complexity of the dispute also influenced arbitral effectiveness among the cases, but through award favourability. In this study, the researcher makes a distinct contribution to knowledge by demonstrating that award favourability and the control model of procedural justice are the components of organisational justice that did influenced arbitral effectiveness in the cases studied. Thus, disputants in the cases were more interested in material gains than in maintaining and sustaining their business relations, explaining why the awards were challenged, hence straining their relationships. This instrumental nature suggests that these disputants were less interested in fairness of the process and its outcome, explaining why the influence of award fairness, procedural fairness and interactional justice on arbitral effectiveness was not supported. Despite the ineffectiveness of the cases, participants maintained that they would still refer future construction disputes to arbitration, mainly because of its procedural and interactional justice. Finally, a schematic framework was synthesized from the data analysis results. The framework requires implementation of institutional, legal and policy interventions for effective construction arbitration. The proposed interventions include a review of the training curricula to impart soft skills on effective construction arbitration, review of the arbitration rules, standing panels to match arbitrators to the various case complexities and the need for arbitrators to proactively manage their cases. There is also a need for disputants to customize the dispute resolution clauses during the contract drafting stage to incorporate desired

The gravel wearing course used on the unpaved roads within the area covering the sub counties of Butere and Mumias wears out too fast. This makes the roads to be in such a bad state as rutting and potholes develop hence making the re-graveling to be done frequently. This study analyzed processes involved in the stabilization of laterite gravel soil with cane molasses. The main objective was to establish the feasibility of using sugarcane molasses in stabilizing laterite soils for gravel wearing course on unpaved roads in Butere and Mumias counties. Other objectives were; to determine the physical, mechanical and chemical properties of laterite gravel soil used on unpaved roads in Butere and Mumias counties, to establish the chemical properties of sugarcane molasses used to stabilize the laterite gravel soil for unpaved roads and to determine the optimum performance of laterite gravel soil stabilized with sugarcane molasses for unpaved roads. Molasses was used in this study because it contained some elements/compounds which are known to react with laterite soil and change characteristics of the soil. Tests were carried out to determine the chemical composition of molasses and those of laterite gravel. It was evident that 2% cane molasses by weight of dry soil was the optimum for effective stabilization of lateritic soil. The study established that neat laterite soil specimens gave lower California Bearing Ratio values than one mixed with cane molasses. The increase in California Bearing Ratio values for laterite soil mixed with cane molasses higher than those of neat laterite soil was an indication that cane molasses caused the strength of the soil to increase and therefore it stabilized laterite soil. Sugarcane molasses improved the engineering qualities of the soil

Accessibility is one of the Key Performance Indicators (KPI) that is used by Long Term Evolution Mobile Networks to check on the quality of the services offered to mobile users. A number of techniques have been used to allocate resources to users. These methods have experienced challenges in terms of allocating multiple resources at high data rates due to the ever growing demands for mobile users within existing resources. This has prompted continuous research in optimization of resource allocation on the existing systems. Due to this, improving resource allocation techniques is a viable area of research in Orthogonal Frequency Division Multiple Access (OFDMA) networks. This is with reference to power levels, Signal to Interference plus Noise ratio (SINR) and limited resource availability to multiple users requesting for resources in a femtocell. A combinational resource allocation scheme is hereby presented in which the available resource blocks are taken into account alongside the users’ resource requests. Signal to Interference plus Noise Ratio computation is then done per user. In addition, all possible arrangements of all users are evaluated to determine the highest SINR levels hence, the best combination of users in comparison to resource requests to allocate the resource blocks at the femtocell. Fairness is also utilized in situations where low SINR valued users have been left out of the femtocell resource allocation. In this case, a resource is reallocated from the next lowest SINR valued user to the user who has been left out to enable the user to communicate. The proposed combinational algorithm is tested in four scenarios. The first scenario tests the algorithm in a femtocell where six users need to only connect and synchronize to the femtocell. In this case, only one resource is required per user and there are only four available resources. The algorithm prioritizes the users with high SINR values and allocates each one of them a resource. The second scenario considers six users who are requesting for more than one resource for data transmission. When the users are allocated resources, one user is found to be left out.