Journal of the Ghana Institution of Engineering

Design and simulation of an exhaust muffler for a single cylinder diesel engine for the Wuzheng tricycle model 7YPJ-1750PD

Emmanuel A. Akugre — 2024-06-28

Exhaust muffler systems are mechanical devices used to absorb and attenuate the noise level of exhaust gases as they enter the atmosphere. This work was aimed at designing and simulating the performance of an exhaust muffler system for the Wuzheng tricycle model 7YPJ-1750PD using its simple expansion chamber as a benchmark to lower the engine exhaust noise by minimising the backpressure. A combination muffler was designed alongside a simple expansion chamber. The two were assembled using solid Edge CAD software. The system was made to undergo CFD and harmonic acoustic simulations using the ANSYS FLUENT software to check its working conditions and performances. It was observed that the assembled muffler system reduced the noise level of the original muffler by 15 dB with a minimal effect on the engine. The assembled muffler system also had a lower average backpressure (911.3 Pa) as compared to that of the original muffler (1151.6 Pa). From the simulation results, the combination muffler was found to be more efficient in attenuating engine exhaust noise levels as compared to the original muffler.

Design and construction of a collapsible tarpaulin-lined pond for aquaculture production

Shadrack K. Amponsah — 2024-06-28

Aquaculture basically refers to the technique of growing fish in tanks or cages to supplement or replace wild fisheries. Despite many advances in culture system development, traditional aquaculture systems do not allow for both flexibility of use and water re-circulating. With the aim of promoting sustainable aquaculture through simple and flexible re-circulating aquaculture systems, a collapsible tarpaulin-lined pond was developed to provide culturing space for 1000 pieces of African Catfish (Clarias gariepinus) or 500 pieces of Nile Tilapia (Oreochromis niloticus) assuming a survival rate of 100 %. A circular geometry was selected for the pond with diameter and height of 4.3 m and 0.9 m, respectively. A pentadecagon framework assembly consisting of connecting rods, angle connectors and stands was designed and constructed of galvanised steel pipes to support the high-grade canvas tarpaulin tank. The tank can safely withstand water and fish load at full capacity without failure at maximum stresses of 0.11 MPa, 0.17 MPa, 0.13 MPa, and 6.26 MPa, representing stress at the tarpaulin’s base, shear stress on connecting pipes, compressive axial stress on the leg, and bending stress, respectively. A biological filtration unit was installed on the tank to culture African Catfish at a stocking density of 78 fish/m³ or 39 fish/m³ for Nile tilapia. This novel aquaculture technique offers a more sustainable and controlled means of producing food and other aquatic products to meet the increasing global demand.

Perception of road users on impact of delayed road construction projects on livelihoods in Ashanti Region

Abena A. Obiri-Yeboah — 2024-06-28

Road construction delays in Ghana's Ashanti Region have detrimental impacts on livelihoods and health risks for residents and road users. This study examines road users’ perceptions (drivers, passengers, pedestrians, and residents) of construction delays and their effects on livelihoods. Data was collected from 2252 respondents using a structured questionnaire and purposive/random sampling across six road projects. This study employed both random sampling and purposive sampling methods, as it aimed to achieve a balance between ensuring representativeness within each category of road users while also targeting individuals with pertinent experiences and knowledge related to road construction delays. This approach allowed for a comprehensive understanding of the issues under investigation while maximizing the efficiency of data collection within the constraints of the study scope and resources. Principal component analysis identified poor management as a major cause of delays, resulting from inadequate project supervision, communication, contractor experience, financing, equipment breakdowns, delayed payments, and late project initiation. Users faced challenges in transportation, business, health, and the environment. However, no significant positive relationship was found between delays, economic activities, and livelihoods. Recommendations include merit-based project awards, proactive contractors with competent managers for effective planning and evaluation, improved communication among stakeholders, adequate funding to reduce delays, and long-term impact assessments through road user tracking. The limitation of this study is that it solely focusses only on Ashanti Region; therefore, extending the research to other regions in Ghana is suggested.

Construction delay impact on asphalt pavement structural performance: the case of N6 highway in Ghana

Kenneth A. Tutu — 2024-06-28

Cost, environmental, and social impacts of road construction delay have been widely investigated, but not its impacts on pavement structural performance. This study conducted pavement structural analysis and distress survey on a section of the N6 Highway in Ghana that had experienced more than a decade of construction delay to examine the impact of the delay on pavement structural performance. The pavement structure and its variants (representing different construction stages) were mechanistically modeled in WESLEA, a layered elastic pavement analysis program, to determine critical pavement strains for fatigue and rutting performance prediction. Also, various pavement structural design scenarios, simulating different construction stages and traffic loading, were analyzed using the American Association of State Highway and Transportation Officials (AASHTO) flexible pavement design procedure to examine the effects of construction delay on pavement structural capacity. The mechanistic analysis showed that trafficking a partially completed pavement considerably increases critical strain levels and exposes the pavement to a higher risk of fatigue and rutting damage. Large structural capacity deficits were obtained for the incomplete pavements: the thinner the in-situ pavement structure and the longer the construction delay, the greater the structural capacity deficit and the greater the damage risk. Opening incomplete pavement structures to traffic for a long time must be avoided because the associated high critical strains and inadequate in-situ structural capacity can induce premature failure, as corroborated by the distress survey findings. Construction staging specifications must be strictly enforced, while construction delay must be avoided and, if impossible, its effects minimized through effective project construction management.

Fossil evidence in the Bimbila Limestones of the Oti Group in the Voltaian Basin of Ghana

Theresa N. Zobah — 2024-06-28

This study investigates the presence of fossil in the Bimbila Limestones of the Oti Group of the Voltaian Basin of Ghana. Geological field mapping, petrographic and mineralogical analyses was used to investigate the organic matter (fossil) presence in the limestones. Results from the comprehensive study identified the Bimbila Limestones to have some microfolds and varve structures in outcrops as a result of marine depositional environment. Some are noted to be homogenous with no quartz or barite while others have quartz/barite. Petrographic analyses revealed that, the most abundant mineral is dolomite with other minerals present being micrite, chert, quartz, calcite, and iron oxide. Under the microscope, the Bimbila limestones were noted to be fossiliferous and hence providing inferred evidence of bioactivity preserved in the limestones. These fossils were inferred to be biogenic materials, possibly skeletal fossil and brachiopods remains probably derived from marine organisms.