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Energy and Power Engineering 2022年第3期14卷 147-155页

作者： Paul Njogu Francis Xavier Ochieng Benard Ogembo stephen ondimu Christopher Kanali Erick Ronoh Daniel Omondi Hiram Ndiritu Institute of Energy and Environmental Technology JKUAT Nairobi Kenya School of Biosystems and Environmental Engineering JKUAT Nairobi Kenya School of Mechanical and Manufacturing Engineering JKUAT Nairobi Kenya

Mesophilic biogas production and substrate decomposition is one of the significant limiting steps in biogas generation. The rate of generation and quality often affect the viability of biogas systems. This study assessed the potential for biogas process catalysis using powdered Sorghum bicolor L., Zea mays, and Pennisetum glaucum. The kinetics and biogas generation processes were studied. Experiments were conducted in 1 m3 tubular batch reactors, where batches were dosed with various organic biomolecules. Results show that the use of P. glaucum L. and S. bicolor L. reduced the biogas retention times significantly. Biogas generation commenced after the first day for digesters fed with S. bicolor L. and P. glaucum L. while one with Z. mays and control occurred on day two. The rate of biomethanation and methane content were enhanced. S. bicolor L. led to the highest methane content. Findings reveal that locally available organic biomolecules improved biogas quality and quantity.

关键词： Mesophilic Kinetics Biomolecules Biomethanation Reaction Rates Anaerobic

Environmental and energy requirements for different production biomass of Nile tilapia(Oreochromis niloticus)in recirculating aquaculture systems(RAS)in Kenya

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Aquaculture and Fisheries 2021年第6期6卷 593-600页

作者： Daniel Mwendwa Wambua Patrick G.Home James M.Raude stephen ondimu Department of Soil Water and Environmental EngineeringJomo Kenyatta University of Agriculture and TechnologyP.O.BOX 62000-00200NairobiKenya Department of Agricultural and Biosystems Engineering Jomo Kenyatta University of Agriculture and TechnologyP.O.BOX 62000-00200NairobiKenya

Recirculating Aquaculture Systems(RAS)offers a better option to increase aquaculture production with limited land and water resources while minimizing water pollution.The biggest challenges in RAS is to maintain favorable water quality for the fish to thrive.The practice of RAS in Kenya is minimal with the improper matching of RAS components and production densities for the existing few and in most cases,leading to a system failure.This study aimed at evaluating environmental and energy requirements for different production biomass of Nile tilapia in a RAS established in a controlled environment.Both production densities and water flow rates were varied while at the same time,the water quality parameters(dissolved oxygen,ammonia,pH,electrical conductivity and temperature)were monitored.The energy consumed for pumping and aeration was also monitored.Tilapia stocking biomass varied from 2.3 kg/m^(3) to 10 kg/m^(3) while flow rate was varied from 2.0 L/min and increased at intervals of 1.0 L/min to the maximum attainable flow rate of 10.0 L/min.Crushed pumice rock packed in a 1000 L tank and equipped with a bell siphon was used as the biofilter.Ammonia removal reduced with increasing flow rate with removal rates of 75%at 2.0-3.0 L/min to 9%at 8.0-10.0 L/min.The water pH increased with increasing flow rate with R^(2) ranging from 0.4 to 0.9.Electrical conductivity increased with flow rate from 112 mg/L to as high as 209 mg/L.Dissolved oxygen increased with flow rate and ranged from 1.0 mg/L to 7.0 mg/L.Energy consumption increased with flow rate and raged from 0.4 kW h at 2.3 kg/m^(3) stocking biomass to 2.4 kW h at 10 kg/m^(3)stocking biomass.High stocking densities and flow rates resulted to lower purification efficiencies and higher power consumptions than low stocking densities and flow rates.In order to maintain good RAS water quality,increased production and profits among farmers using RAS in Kenya,there is need to give proper advice on the right combination of stocking biomass,power,and water flow rate.In addi

关键词： Biofilter Flow rate Purification efficiency Stocking biomass Water quality

Adoption Strategy for Cloud Computing in Research Institutions: A Structured Literature Review

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Journal of Computer and Communications 2023年第4期11卷 63-78页

作者： Asnath Nyachiro Kennedy ondimu Gabriel Mafura Department of Information Technology Institute of Computing and Informatics Technical University of Mombasa Mombasa Kenya

Currently, Kenyan research institutions Information Technology operations use external storage, within or without institutional network environments. This study presents a structured literature review of a cloud computing adoption strategy for research institutions in Kenya. The reviews objectives are: 1) to establish the characteristics/peculiarities and IT environments of research institutions in Kenya, 2) current cloud computing technologies, adoption approaches and drivers in the adoption of cloud computing. The findings are that there is need for an adoption strategy for Cloud computing in the Kenyan research Institutions that will use a DOI and TOE combined approach while addressing technological, organizational and environmental factors. The findings are used to propose a cloud computing adoption strategy for the Kenyan Research Institutions in future research.

关键词： Cloud Computing Research Institutions Strategy Adoption

Natural regeneration and ecological recovery in Mau Forest complex, Kenya

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Open Journal of Ecology 2013年第6期3卷 417-422页

作者： James Mwangi Kinjanjui Moses Karachi Kennedy Nyambuti ondimu Department of Geography Egerton University Egerton Kenya Department of Natural Resources Egerton University Egerton Kenya Department of Resource Survey and Remote Sensing Nairobi Kenya

This study investigated natural ecological recovery in parts of Western and Southwestern blocks of theMauForestcomplex that had experienced varied levels of disturbance. The extent and speed of regeneration in the disturbed regions since the eviction of the setter population were not known. This study thus now provides current baseline data on plant distribution, germination of soil bank seeds, and soil nutrient content. The number of tree species recorded at different levels of disturbance were in increas- ing order: moderately disturbed (MDF) > undisturbed (UDF) > heavy disturbed forest (HDF). Forest clearing reduced forest basal area and forest stocking of big trees (dbh ≥40 cm) in the HDF by more than 4 and 6 times, respectively, than those in UDF. Tree importance values indicated a reduction in commercially valuable species in HDF. Early colonizers and fire tolerant species were predominant in the HDF whereas non-commercial species dominated MDF. Viable soil seed reserves decreased with soil depth in all forests but content between 0 -20 cmsoil depth showed a potential to support regeneration. Total N, organic C and available P decreased with increase in forest disturbance. Overall, the disturbed sites showed a general potential for ecological recovery and natural regeneration to UDF status.

关键词： Disturbance Regeneration Soil Seed Bank Germination Nutrients

Assessing Tree Species Dominance along an Agro Ecological Gradient in the Mau Forest Complex, Kenya

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Open Journal of Ecology 2014年第11期4卷 662-670页

作者： Mwangi James Kinyanjui Chris A. Shisanya ondimu Ken Nyabuti Wargute Patrick Waqo Merceline Awuor Ojwala Department of Geography Egerton University Njoro Kenya Department of Geography Kenyatta University Nairobi Kenya Department of Resource Surveys and Remote Sensing Nairobi Kenya

Species relative dominance by basal area was assessed along an agro ecological gradient in the Mau Forest Complex (MFC). Trees were recorded per species and diameter at breast height (D1.3) for size class D1.3 ≥ 10 cm in 60 quarter hectare plots distributed in 7 agro ecological zones (AEZ) namely LH1, LH2, LH3, LH4, UH0, UH1 and UH2. Basal area per species was used to calculate species relative dominance i.e. the proportion of basal area by a species to the total basal area of the AEZ. Species associations were analysed as the group of highly ranked species in each AEZ. Sorensons similarity index was used to calculate the proportion of similar species among AEZ. Analysis of variance compared basal area among AEZ and Tukey’s multiple comparison test used to identify specific AEZ with differences. Tabernaemontana stapfiana (Britten) was ranked first in LH1, UH1 and UH0 with relative dominance values of 22.66%, 22.89% and 30.73% respectively. It was however not recorded in any other AEZs. Dombeya goetzenii (K. Schum) occurred in 6 of the 7 AEZs but had moderate dominance values in each of the 6 AEZs. The sum of dominance values per species in all AEZs indicated no species mono-dominance and different species dominated at different AEZs. Co-dominance resulted in species associations like Tabernaemontana-Allophylus-Eke-bergia-Albizia in LH1, Juniperus-Dombeya-Casearia-Prunus in LH2, Acokanthera-Cussonia-Olea-Teclea in LH4 and Tabernaemontana-Syzygium-Podocarpus-Neoboutonia in UH1. Species richness was highest in UH1 and had the highest similarity indices with those of other AEZs. The UH1 had a species similarity of 67% with LH1, 63% with LH2 and 56% with LH4. However, species in the very humid zone UH0 differed with those of the drier lower highland zones (UH0 vs LH3 and vs LH4 = 31% and 37% respectively). Basal area differed significantly among AEZ ( = 3.76) showing that they differ in stocking levels. Tukeys test showed that high potential zones of LH1, LH2, UH0, UH1 did not differ and similarly the lower potential

关键词： Species Dominance Basal Area Agro Ecological Zoning