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Modelling mechanical strengths of blended cement concrete incorporating corncob ash and calcite powder: experimental and machine learning approaches
Get PDFThe building and construction sector has focused on sustainable cement alternatives due to the
rise in carbon dioxide emissions caused by rising cement usage. Blended Cement Concrete
(BCC) enhanced with Supplementary Cementitious Materials (SCMs) such as Corncob Ash
(CCA) and Calcite Powder (CP) offers a sustainable substitute. Thus, this study utilized Deep
Neural Networks (DNNs) to predict the Compressive Strength (CS), Flexural Strength (FS), and
Split Tensile Strength (STS) (output variables) of BCC with respect to the mixed design
proportions as input variables using concrete classes 25 and 30 MPa after 3–120 curing days.
The DNNs were chosen for their ability to learn complex patterns and relationships in the data,
making them suitable for predicting the mechanical strengths of the BCC. The models were
trained with an experimental data set consisting of 100 values for each strength feature. A set of
8 raw experimental values were used to verify the accuracy of the developed model. The 8–20-
20–20-1 network structures exhibited the best performance metrics for training, validating, and
testing the input and output variables compared to other architectures. For CS, FS, and STS, the
correlation coefficient (R) values were 99.97, 98.69, and 97.24%. There was a strong correlation
with 98.82, 99.61, and 99.54% R2 for CS, FS, and STS when the developed models were
validated using raw experimental datasets. The standard of BCC integrating SCMs would be
improved by using this approach
Design analysis and fabrication of a 24 - teeth spur gear from HT250 gray cast iron
Get PDFSpur gears are types of gears used for transmitting motion between two parallel shafts.
This machine often encounters failure and downtime as a result of failure of the gear
component. These failures include; pitting, scoring, fracture, wear, and so on. This study
focused on the use of Gray Cast Iron (HT250) to develop a spur gear having 24 teeth
and a protruding connecting shaft to link it to a machine using keys or other means. The
fabrication process that was used to obtain gear was Casting which was done in the
Foundry Workshop of the Mechanical Engineering Department in Covenant University.
The failure indicated on the gear was a cyclic failure due to fracture. The stress analysis
was carried out on this element using this software. A cyclic force of 10 N was subjected
to the gear and the following values were obtained: the maximum Von-mises stress was
3.548 x 105N/m^2 and the minimum was 5.629 x 10-1N/m^2, The maximum
displacement or deflection gotten was 6.306 x 10-5 mm and minimum is 1 X 10-30 mm,
The maximum strain gotten was 2.599 x 10^-6 and the minimum was 9.825 x 10^-12.
Various parameters were used to obtain the nature of failure on the material such as the
force on 10 N on a single tooth and on all 24 teeth, a torque of 10 N/m, temperature of
50-degree, pressure of 20 Pa and centrifugal force of 5 rad/s. These results to variation
in the von mises stress
Heat Transfer Characteristics of Al2O3 Based Nano refrigerants in The Evaporator and Condenser of Vapor Compression Refrigeration Systems
Get PDFThe performance and energy consumption of the vapor compression refrigeration system
(VCRS) is influenced by the rate of heat transfer between the system and its environment.
Two-phase flow, boiling with heat transfer occur within the evaporator and the condenser of
the VCRS. The improvement in two-phase flow, boiling and heat transfer coefficient in these
components using nano refrigerants possess the propensity to increase the system’s
performance and energy efficiency and reduces the energy carbon footprint of the system.
The influence of nanoparticle concentration of aluminum oxide (Al 2 O 3 ) on the two-phase
flow heat transfer in the condenser and the evaporator using R134a and R600a refrigerants
in the VCRS was analyzed in this study. The ANSYS fluent software was employed to
model and analyze the process in the condenser and evaporator. The result obtained
showed that convective heat transfer of pure R600a and Al 2 O 3 /R600a nano refrigerants
was higher than that of pure R134a and Al 2 O 3 /R134a nano refrigerants. The Prandtl and
Nusselt numbers decreased as the nanoparticle concentration increased. Thermal diffusion
was more prominent than the momentum diffusion as the temperature increased, despite
the increase in the nanoparticle concentration. The numerical simulation results established
that the convective heat transfer coefficient, Nusselt number and Prandtl number of the
nano refrigerant depends on the mass concentration of nanoparticles
The Role of Value Engineering in Building Construction Resources Optimisation and Environmental Protection: An Overview
Get PDFBuilding construction is an integral part of national economic development. Nevertheless, it
requires enormous capital to implement sustainable building construction. Construction
activities contribute to environmental degradation and pollution by material extraction and
carbon emissions, amongst other problems. Stakeholders in the industry continue to seek
ways to optimise resources to save costs and protect the environment. Value Engineering
(VE) seeks to strike a balance between costs and functions performed by buildings and
infrastructures without compromise. Therefore, this survey aims to understand how VE
principles can optimise building resources and protect the environment without loss in
quality, performance, and reliability. The assessment reveals that using VE principles
optimises building functions at the lowest overall cost without affecting quality and
performance. The approach addresses the oversizing of structural elements of buildings
and mechanical and electrical systems. It resolves the complexity of building sizes and
shapes via material diversification. It identifies the function of a building before investing to
save costs and avoid project abandonment. The practice has the potential to provide an
environmental advantage through the dematerialisation of the building structures to mitigate
greenhouse gas emissions linked to the built environment occasioned by the energy
released from fossil fuels. The method simplifies multi-objective resource optimisation
associated with supertall building construction. In addition, abandoned projects can be
revived by identifying the status and challenges with the project and suggesting strategies
that facilitate the easy take-off of the rehabilitation of such projects. Furthermore, building
projects can achieve green and sustainable construction by adopting value engineering
strategies
Review of Passive Design Strategies for Sustainable Development: A Focus on Energy Efficient Strategies for Tropical Climates
Get PDFIn tropical climates, where high
temperatures and humidity levels pose challenges to
energy efficiency, the adoption of passive design
strategies becomes crucial. With the use of
qualitative data, this study analysed secondary
sources such as experiments and scholarly materials
from reputable databases such as Google Scholar,
ResearchGate, Scopus and Covenant University
Repository. The systematic review of published
literatures presented in themes examined how
passive design strategies aid energy efficiency for a
sustainable built environment in tropical buildings.
70 publications spanning the years of 2002-2024
were content analysed and descriptively presented.
The findings showed that proper incorporation of
passive design solutions is both advantageous to
man and the environment. It further makes for
reduced energy consumption in tropical buildings.
The study recommended intentional designer
responsibility, policy implantation and better
innovative solutions
Computational simulation of the effects of blood flow velocity on atherosclerosis progression in a human carotid artery
Get PDFBackground
Atherosclerosis is a build-up of low-density lipoproteins (LDL) in the
channels of blood vessels. This occludes the vessels and, occurring in
the carotid arteries, portends conditions that favour stroke. This work
is an attempt to mathematically represent the physiological process of
atherosclerosis caused by plaques on the walls of the human arteries.
Aim
Provide insight into the effect of blood flow velocity on wall shear
stress and its implications on atherosclerosis progression in a human
carotid artery via computational simulation.
Methods
The effect of blood velocity on plaque growth and progression is
simulated using COMSOL multi-physics. The human carotid was
modeled in 2-D with Stokes law for model flow. The simulation began
with a plaque-free vessel with velocities of 30 m/s – 125 m/s.
Results
Results showed that the rate of plaque initiation dropped as the blood
velocity increased from 30 m/s to 125 m/s; higher inlet velocities gave
lower plaque growth; the highest degree of 30% stenosis was
recorded at a blood velocity of 30 m/s. Plaque height significantly
affects the Plaque wall Stress, PWS, and its distribution around the
plaque and arterial wall; higher plaque heights experience higher velocity distribution around the plaque, causing a higher force
associated with blood flow around the plaque, resulting in higher
compression stress. More compressional stresses are localized
around the root, which would encourage growth as well as possible
rupture at higher velocities. These ruptured plaques potentially
narrow or block the arteries and prevent blood flow. This is
atherosclerosis and can lead to a heart attack.
Conclusion
Results from this study can find significant use in the understanding,
management, and treatment of atherosclerosis since the regulation of
blood velocity and pressure plays a major role in the progress of
atherosclerosis in the carotid artery which raises the risk of stroke
Adsorptive removal of Fe and Cd from the textile wastewater using ternary bio‑adsorbent: adsorption, desorption, adsorption isotherms and kinetic studies
Get PDFTernary bio-adsorbent was synthesized by using sisal fiber as a base with the integration of conductive polymer; polyaniline
(PANI), supported with zero-valent iron nanoparticles by chemical activation with potassium hydroxide. The
activation temperature impact on adsorption properties of Sisal fiber composite activated carbon was studied. The
activation temperatures had a major effect on adsorption process as 100% removal efficiency was attained at 800 °C
activated temperature. Scanning electron microscopy (SEM) was used for surface analysis of the adsorbent. Adsorption
isotherms (Langmuir, Freundlich and Temkin) were examined and the negative values of 1∕n
F demonstrated that the
adsorption data does not match with Freundlich model for chemisorption. The pseudo second order and Elovich kinetics
correlation coefficients for the retention of Fe and Cd to solid-phase interface at SF-800/NP/PANI (C) offered a better
correlation for the bio-adsorption of Fe and Cd than pseudo first order kinetic. However, the pseudo second order kinetic
attained a surpassing interaction for the bio-adsorption of Fe (0.989) than Cd (0.966); while the Elovich kinetic attained
a surpassing interaction for the bio-adsorption of Cd (0.975) than Fe (0.945). The recovery and recycling stability of the
bio-adsorbent composites were studied
Scrutinizing the level of awareness and adoption of distributed ledger technology in the Nigerian construction industry
Get PDFPurpose
This study aimed to investigate and analyze the level of awareness and
adoption of distributed ledger technologies (DLTs) within the Nigerian
construction industry. The focus was on addressing the current state of DLT
utilization, identifying challenges and opportunities and proposing strategies to
enhance the integration of DLTs into the construction processes and practices
of Nigerian professionals and organizations.
Design/methodology/approach
The research was underpinned by a robust theoretical and conceptual
framework, drawing from established theories of technology adoption. A
comprehensive literature review guided the identification of various DLT types.
This informed the development of a well-structured questionnaire, which was
then distributed to Nigerian construction professionals. The collected data
underwent analysis using percentages, frequencies, mean scores, the
Kruskal–Wallis H-test and the Shapiro–Wilk test.
Findings
A significant finding of this study reveals a generally low awareness and
implementation of DLT among construction professionals in Nigeria. These
findings emphasize the urgent need for comprehensive strategies to bridge
the gap between awareness and adoption of DLT within the Nigerian
construction industry.
Practical implications
Industry associations, regulatory bodies and educational institutions can
collaborate to develop specialized programs aimed at familiarizing
professionals with the benefits and applications of DLTs. Additionally,
technology providers and policymakers can leverage these findings to design
user-friendly interfaces and guidelines for seamless DLT integration into
construction processes.
Originality/value
This study contributes to the existing body of knowledge by providing a
comprehensive assessment of the awareness and adoption of DLTs
specifically within the Nigerian construction industry. While the global
recognition of DLT’s potential in construction is acknowledged, this research
delves into a regional context, shedding light on the specific opportunities
within Nigeria. Furthermore, the study’s identification of a gap between
awareness and implementation highlights a critical area for future exploration
and development in the field of construction technology adoptio
Reintegration Programs and the Willingness of Displaced Persons to Return Home: Analyzing the Role of Social Infrastructure in North-East Nigeria
Get PDFThis study explores the impact of Boko Haram’s violence on northern Nigeria, particularly
focusing on the willingness of conflict-induced internally displaced persons (CIIDPs) to return
home and the role of restoring social infrastructure in this process. We employed a mixedmethods
approach, collecting data from 866 randomly selected internally displaced persons
(IDPs) across eight camps in North-East Nigeria and conducting focus group discussions in two
of these camps. Our findings, as revealed by correlation analysis, suggest a positive albeit weak
link between the restoration of social infrastructure and the willingness of IDPs to return to their
homes. Specifically, the selected social infrastructure improvements accounted for a modest 3%
change in the willingness to accept a voluntary return. This implies that while restoring social
infrastructure plays a role, it alone is insufficient to significantly boost the willingness of IDPs in
North-East Nigeria to return voluntarily. However, our regression analysis offers more nuanced
insights. It indicates that restoring access to water and rebuilding access roads in affected
communities can have a substantial impact on motivating CIIDPs to return home. Therefore, we
conclude that while restoring social infrastructure is a factor, it should not be viewed as the sole
solution for promoting willingness to return in a post-conflict context. To address the broader
issue, we recommend that governments and policymakers in conflict-affected communities
prioritize the restoration of water sources and access roads, as these appear to be critical factors
in encouraging the return of IDPs. Additionally, further research is necessary to identify other
essential needs and interventions to facilitate the return of CIIDPs to their home communities