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Modelling and optimization of multiple replacement of supplementary cementitious materials for cement composite by response surface method.
Get PDFthis article was published on Cleaner Engineering and Technology at 7,of march 2024 in Elsevier Ltd its available in full text and Doi is https://doi.org/10.1016/j.clet.2024.100735Supplementary cementitious materials are beneficial in improving performance and lessening the cement con-
sumption with highly lessening CO2 emission. Many researchers used blast furnace slag, bentonite, and active
limestone separately or two of them together to improve the performance of cementing materials, however, it is
not well known how all react together in cement composite materials. So, the present study used modeling and
optimizing the replacement of blast furnace slag, raw bentonite, and active limestone each by the doses of 0 to
20% to maximize strength and minimize the fresh bulk density of cementing materials by central composite
design-response surface method (CCD-RSM). The results found, the employment of blast furnace slag, bentonite,
and active limestone in the cement composite materials generally lessens the early strength compared to the
control mixture. However, the replacement of blast furnace slag and active limestone by 20% significantly im-
proves the 28-days compressive strength while employing raw bentonite by 20% reduced compressive strength
by 6.45% compared to the control mixture. However, blending raw bentonite with active limestone by half
improved the compressive strength. Besides these, the substitution of bentonite and active limestone reduces the
fresh bulk density and flexural strength than the control mixture. Generally, the study optimized depending on
the criteria of maximizing strength and minimizing fresh density and found the mix design replacement of blast
furnace slag 1.01%, raw bentonite 5.30%, and active limestone 20% that improves 28 days compressive strength
simultaneously reduces fresh bulk density in addition to replacing more than 54 different optimized design mix
results
Evaluating the performance of faecal sludge dewatering technologies in urban settings of developing African countries: a review
Get PDFThis research article was published in International Journal of Environmental Health Research, 2024Inadequate dewatering technologies are reported as the dominant challenge in handling faecal sludge (FS) within urban settings of most African countries. Studies have been carried out to evaluate the efficiencies of unplanted sand drying beds (USDBs), decentralized wastewater treatment systems (DEWATS), and geo-tubes. However, limited information is available on comparative capabilities in dewatering the FS. This work reviewed treatment efficiencies by assessing the reported actual waste removal capacities and ascertaining if they align with the design removal provisions. Peer-reviewed papers, books, and technical reports from trusted sources were examined. The results show that all the technologies perform best in dewatering the FS; however, USDBs are widely adopted for city-wide treatment, and the other two are suited for decentralized communities. The USDB is challenged by frequent clogging and poor quality of dewatered sludge when reused or recycled in the production of solid fuel and compost due to sticking sand after sludge harvesting. The DEWATS and geo-tubes increase operational costs when used to treat the FS at a large scale. More studies should be conducted to explore locally made, cost-effective filter media and technologies to enhance the dewatering quality and quantity of the FS and increase the quality of recycled by-products
Characterization of soil health and nutrient content status across the North-East Maasai Landscape, Arusha Tanzania
Get PDFThis research article was published in the Environmental Challenges, Volume 14, 2024Soil fertility management has been a great challenge to smallholder farmers in the Northern Tanzania, especially
in the Maasai landscape. Therefore understanding the nutrient status become important to forecast productivity,
promote sustainability, and propose an appropriate technique for crop productivity sustainability. The study
examines soil fertility status of the Maasai landscape. Systematic approach known as the Land Degradation
Surveillance Framework (LDSF) were used to identify soil sampling points. A total of 604 soil samples from two
soil depth (0 – 30 and 30 – 50 cm) were collected for physiochemical properties analysis using Mid-infrared
(MIR) spectroscopy. The chosen level for determining statistical significance, was set at P = 0.05. Results
showed a significant differences (P < 0.01) for particle size distribution, SOC, EC, CEC, TN, pH, N, P, K, Ca, S,
Mg, Mn and Zn across the landscape zones. It was observed that soil parameters such as pH (6.62 – 7.44), CEC
(27.59 – 32.82 meq/100 g), and EC (90.12 - 121.93 μS/cm) were in the adequate and acceptable range while
SOC (0.89 – 1.89 %) was observed to be in low amount. Other nutrients such as N (0.09 – 0.14 %), P (9.46 –
14.87 mg/kg), and K (175.91 - 293.5 mg/kg) were in inadequate amounts except for the S (12.9 – 15.43 mg/kg)
which was in optimum, Ca (3117.5 - 4155.31 mg/kg) ranged between low to optimum, and Mg (556.95 - 603.26
mg/kg) was in excessive amounts. However, Mn (114.13 mg/kg – 128.95 mg/kg) was in excess. This study found
that, there is a significance difference on soil fertility status across the landscape. Major soil nutrient fertility
constraints found were N, P, Ca, and K for some soils. The study recommends that interventions to address the
issue of soil fertility in the northeast Maasai landscape should consider the altitude issue due to variations in soil
health and nutrient content
Rare earth elements and uranium in Minjingu phosphate fertilizer products: Plant food for thought
Get PDFThis Research Article was published by the Resources, Conservation and Recycling , 2024Minjingu phosphate ore is Tanzania's sole domestic supply of phosphorus (P). The ore contains medium to high concentrations of naturally occurring P2O5 (20–35 %) and relevant concentrations of uranium and rare earth elements (REEs) are also suspected to be present. Currently, neither uranium nor REEs are recovered. They either end up in mine tailings or are spread across agricultural soils with fertilizer products. This work provides a first systematic review of the uranium and REE concentrations that can be expected in the different layers of Minjingu phosphate ore, the way the ore is presently processed, as well as a discussion on alternative processing pathways with uranium/REE recovery. The study analyzed ten distinct Minjingu phosphate ore layers, four mine tailings, and five intermediate and final mineral fertilizer products from the Minjingu mine and processing plant located in northern Tanzania. The results confirm that the uranium concentrations and to a lesser degree, the REE concentrations are indeed elevated if compared to concentrations in other phosphate ores. The study does not identify a significant risk resulting from this. The development of techno-economic solutions for more comprehensive utilization of Minjingu ore is, however, strongly encouraged and suggestions on such processes are provided
Review of Sources of Uncertainty and Techniques Used in Uncertainty Quantification and Sensitivity Analysis to Estimate Greenhouse Gas Emissions from Ruminants
Get PDFThis research article was published by sustainabilityUncertainty quantification and sensitivity analysis are essential for improving the modeling
and estimation of greenhouse gas emissions in livestock farming to evaluate and reduce the impact
of uncertainty in input parameters to model output. The present study is a comprehensive review of
the sources of uncertainty and techniques used in uncertainty analysis, quantification, and sensitivity
analysis. The search process involved rigorous selection criteria and articles retrieved from the Science
Direct, Google Scholar, and Scopus databases and exported to RAYYAN for further screening. This
review found that identifying the sources of uncertainty, implementing quantifying uncertainty, and
analyzing sensitivity are of utmost importance in accurately estimating greenhouse gas emissions.
This study proposes the development of an EcoPrecision framework for enhanced precision livestock
farming, and estimation of emissions, to address the uncertainties in greenhouse gas emissions and
climate change mitigatio
Review of Sources of Uncertainty and Techniques Used in Uncertainty Quantification and Sensitivity Analysis to Estimate Greenhouse Gas Emissions from Ruminants
Get PDFThis research article of sustainability was published by MDPI,2024Uncertainty quantification and sensitivity analysis are essential for improving the modeling
and estimation of greenhouse gas emissions in livestock farming to evaluate and reduce the impact
of uncertainty in input parameters to model output. The present study is a comprehensive review of
the sources of uncertainty and techniques used in uncertainty analysis, quantification, and sensitivity
analysis. The search process involved rigorous selection criteria and articles retrieved from the Science
Direct, Google Scholar, and Scopus databases and exported to RAYYAN for further screening. This
review found that identifying the sources of uncertainty, implementing quantifying uncertainty, and
analyzing sensitivity are of utmost importance in accurately estimating greenhouse gas emissions.
This study proposes the development of an EcoPrecision framework for enhanced precision livestock
farming, and estimation of emissions, to address the uncertainties in greenhouse gas emissions and
climate change mitigatio
Review of Sources of Uncertainty and Techniques Used in Uncertainty Quantification and Sensitivity Analysis to Estimate Greenhouse Gas Emissions from Ruminants
No full textThis research article was published by Sustainability,2024Uncertainty quantification and sensitivity analysis are essential for improving the modeling
and estimation of greenhouse gas emissions in livestock farming to evaluate and reduce the impact
of uncertainty in input parameters to model output. The present study is a comprehensive review of
the sources of uncertainty and techniques used in uncertainty analysis, quantification, and sensitivity
analysis. The search process involved rigorous selection criteria and articles retrieved from the Science
Direct, Google Scholar, and Scopus databases and exported to RAYYAN for further screening. This
review found that identifying the sources of uncertainty, implementing quantifying uncertainty, and
analyzing sensitivity are of utmost importance in accurately estimating greenhouse gas emissions.
This study proposes the development of an EcoPrecision framework for enhanced precision livestock
farming, and estimation of emissions, to address the uncertainties in greenhouse gas emissions and
climate change mitigation
The neuroprotective effects of baobab and black seed on the rat hippocampus exposed to a 900-MHz electromagnetic field
Get PDFThis research article was published by Elsevier, 2024This study investigated the potential effects on the hippocampus of electromagnetic fields (EMFs) disseminated by mobile phones and the roles of baobab (Adansonia digitata) (AD) and black seed (Nigella sativa) (BS) in mitigating these. Fifty-six male, 12-week-old Wistar albino rats were divided into eight groups of seven animals each. No EMF exposure was applied to the control, AD or BS groups, while the rats in the Sham group were placed in an EMF system with no exposure. A 900-MHz EMF was applied to the EMF+AD, EMF+BS, EMF+AD+BS and EMF groups for 1 hour a day for 28 days. Pyramidal neurons in the hippocampus were subsequently counted using the optical fractionator technique, one of the unbiased stereological methods. Tissue sections were also evaluated histopathologically under light and electron microscopy. The activities of the enzymes catalase (CAT) and superoxide dismutase (SOD) were also determined in blood serum samples. Analysis of the stereological data revealed no statistically significant differences between the EMF and control or sham groups in terms of pyramidal neuron numbers (p>0.05). However, stereological examination revealed a crucial difference in the entire hippocampus between the control group and the AD (p<0.01) and BS (p<0.05) groups. Moreover, exposure to 900-MHz EMF produced adverse changes in the structures of neurons at histopathological analysis. Qualitative examinations suggest that a combination of herbal products such as AD and BS exerts a protective effect against such EMF side-effects
IoT-Based Intelligent Charging System for Kayoola EVs Buses at Kiira Motors Corporation in Uganda
Get PDFThis journal was published by Research Square, 2024The increasing popularity of Electric Vehicles (EVs) has led
to a surge in the need for charging stations in Kayoola EV
buses. Most of existing EV charging stations have outdated
features which is challenging to be remotely controlled.
However, current EV charging systems experience with no
remote battery operational charging status, unsafety
control if charging station is faulted, and insecure charging
RFID card payment. This paper, an IoT-based system was
aimed to manage and monitor these EV charging stations.
The battery management system (BMS) sends charging
voltage and current information to charger via Controller
Area Network (CAN) bus. Then, the Raspberry Pi4 receives
and decode CAN charging data to be processed, analyzed
and transmits to the cloud server. Each charger is equipped
with sensors monitoring parameters like charging status,
energy consumption, voltage, current, and time. The user
can access that decoded charging information via android
mobile application and desk remote management system.
Additionally, the system server calculates the battery
charging levels and commend RFID card transaction
payment. The results show that developed IoT-based
intelligent charging system provides and outperforms
minimum and maximum cell voltages of 2.82V and 4.1V,
min. and max. cell temperatures of 37℃ and 40℃
respectively. The charged energy of 10kWh, used energy of
0kWh, charging state indication, low-cell voltage as error
state indication, charging price rate of 500Ugx/kWh, and
full-latch of 0, pack voltage of 483.9V, pack current of
100.1A, battery health of 97%, battery state of charge (SoC)
of 100% and remaining charging time of 38 mins were also
detected and remotely monitored. In conclusion, the
developed system proves 100% of real-time and remote
data access and accuracy, efficiency, security,
accessibility, sustainability, safety charging payment, and
remote battery status monitoring system of EV charging
infrastructure compared to the current charging where it
offers only 58.75% of charging rate
Fabrication of porous carbon nanofiber webs from polyacrylonitrile and cellulose acetate for NaCl removal from water using capacitive deionization
Get PDFThis research article was published by IWA, 2024Capacitive deionization (CDI) has shown potential in addressing freshwater scarcity. CDI's electrode design is a key to better performance as
it determines the extent of water purification. For carbon electrodes, the pore structure is an important factor influencing removal kinetics
and ion storage. Herein, porous carbon nanofibers with diameters ranging from 277 to 348 nm were fabricated from blends of polyacryloni-
trile (PAN) and cellulose acetate (CA) through electrospinning and carbonization. Surface area and pore properties were adjusted by varying
the proportions of the precursors while ensuring no adverse alteration to the products’ tangible properties. Enhanced pore structure and
specific surface area were evident in the blend-based carbon nanofibers. The blend ratio of 2:8 (CA:PAN) had a high specific surface area
of 925.47 m2 /g and a pore volume of 0.7884 cm 3
/g. Correspondingly, a high specific capacitance of 177.5 F/g was attained. Desalination per-
formance was determined in batch mode using 500 mg/L NaCl solution. A salt adsorption capacity of 6.57 mg/g and charge efficiency of 0.46
was obtained for the blend that had 20% CA. The carbon nanofibers demonstrated good desalination stability when used repetitively indi-
cating their excellent potential for practical applicatio