COVENANT JOURNAL OF ENGINEERING TECHNOLOGY

A Review of the Energy and Exergy Analysis of a Cascade Refrigeration System for Process Optimization

2024-02-18T07:49:19+00:00

An overview of thermodynamic energy and exergy analysis is provided in this work with the goal of developing, constructing, and improving a cascade cooling apparatus for extremely low-temperature managing goods and gas-efficient building operations. A review of the classes of cascade systems was carried out, stating the benefits and setbacks. Every part of the refrigeration mechanism cascades was identified, explained, and designed theoretically. Energy and exergy techniques were used to analyze every component of the system separately, model it, and evaluate it to minimize energy destruction. Necessary equations for calculating energy and exergy destructions were outlined to ensure effective modeling and optimization of the system processes. Process losses were identified, determined, and reduced using the application of exergy analysis. There was an improvement in comprehension of the process's deceptive efficiency and energetic effectiveness. The result aids in detecting the locations of energy degradation and mapping out the system's optimal performance. By lowering operational and process design costs and resolving energy- associated environmental issues, the analysis eventually contributed to sustainable growth. This offers a rationale for enhancing an exceptionally low-temperature freezer's functionality for the handling of susceptible-to-heat vaccines. The effective modeling and building of cascade refrigeration systems for zero energy destruction and high efficiency are made possible.

An Experimental Investigation into the Effects of Using Partially Substituted Cassava Peel Ash for Cement in Concrete

2024-06-14T12:17:59+00:00

When placed in landfills, agricultural wastes have been a significant source of contamination to the environment. The rate of consumption of cement being an essential part of concrete cannot be overemphasized. There is need to explore alternative supplementary binding material which is eco-friendly and sustainable towards the production of green concrete. The purpose of this study is to explore the possibility of using cassava peel ash (CPA) as a partial cement substitute in concrete. The partial replacement was achieved in differing percentages of 0%, 1%, 2%, 3%, 4% and 5% by weight of cement in the M20 concrete mix, making use of mix ratio 1:1.5:3. The batched concrete mix samples were cast in cube and cylinder moulds of 100 x 100 x 100mm and 100 by 200 mm respectively and cured for 7, 14, 28, 56 and 90 days. On the fresh concrete mixtures, slump tests were carried out and the split tensile and compressive strengths of the cured concrete cylinders and cubes were evaluated respectively. In the findings derived from the slump test, it is evident that with the incremental augmentation of the percentage replacement of (CPA) within the concrete mixture, there is a discernible augmentation in the workability of the resultant mixture. The results indicated that at 1% cassava peel ash (CPA) replacement, the optimal compressive strength and split tensile strength values were 32.9 N/mm² and 3.9 N/mm², respectively. These values are comparable to those of the control mix with compressive and tensile strength values of 33.1 N/mm² and 4.1 N/mm², respectively. This research investigation unveils the potential suitability of (CPA) as a prospective partial substitute for cement within the composition of a concrete mixture.

A Performance Comparison of Three Machine Learning Algorithms for Urban Land Cover Classification using High-Resolution Imagery

2024-06-10T12:28:14+00:00

Urban land cover classification using high-resolution imagery is important for many applications where detailed and precise urban land cover products are needed. Machine learning algorithms are currently some of the most commonly used methods for classifying high-resolution imagery due to their impressive capabilities. However, the reliability of the land cover products obtained from the classification of high-resolution urban imageries is dependent upon the accuracy of the Machine Learning (ML) classification algorithm used. The need for an appropriate selection of classifiers for urban land cover classification and their applicable settings necessitates the performance comparison of major ML algorithms used for classification. In this study, we compared the performance of three major Machine Learning (ML) classifier algorithms using a high-resolution image dataset of an urban area. The algorithms are Support Vector Machine (SVM), Naïve Bayes, and Ensemble classifiers. The performance of three model types of SVM classifiers namely Medium Gaussian, Linear, and Quadratic SVM, two model types of Naïve Bayes classifiers namely Gaussian and Kernel Naïve Bayes, and three model types of ensemble classifiers namely Bagged Trees, Subspace Discriminant, and RUSBoosted Trees were compared. Performance evaluation was carried out using Confusion Matrix (CM) and Receiver Operating Curves (ROC) plots. Results obtained from the comparison of the three ML classifier algorithms show that the Subspace Discriminant ensemble classifier had the highest accuracy at 85.1%, closely followed by the Medium Gaussian SVM classifier (84.5%) and Gaussian Naïve Bayes classifier (81.5%). This research provides insights into the selection of classifiers for future urban land cover classification and their applicable settings.

High-Performance Concrete Incorporating Almond Leave Ash as Supplementary Cementing Material

2024-07-02T10:38:23+00:00

High-Performance Concrete (HPC) offers greater strength and resilience compared to conventional concrete. Almond leaves frequently clog areas where they are planted and have no recognized commercial value. In this research, Almond Leaf Ash (ALA) was included in HPC in percentages ranging from 0, 5, 10, 15, 20% as a cement additive. Concrete specimens, engineered to possess a minimum strength of 50 N/mm², were poured and underwent water curing for up to 56 days. The workability of the newly mixed concrete was evaluated by analyzing its compacting factor and slump. Furthermore, evaluations were conducted on the density, compressive and split tensile strengths, as well as the internal microstructure of the cured concrete. The workability tests revealed that the concrete stiffened as the proportion of ALA increased. Adding 5% ALA to HPC led to achieving a strength of 56.56 N/mm² after 56 days of curing, surpassing the expected strength. Meanwhile, incorporating 10% ALA attained the targeted minimum strength of 50 N/mm². 15% and 20% of the ALA, however, fell short of the minimum strength. The HPC's split tensile strength followed the same pattern. The results were corroborated by examining the microstructure of the HPC, revealing that substituting 5% ALA for cement yielded the highest strength.

Development of an Infrared Thermometer with SMS Feedback

2024-06-10T13:16:41+00:00

The non-contact infrared thermometer is an essential medical device in hospitals for measuring a patient’s surface temperature while preventing the transmission of infection from one person to another. While taking such measurements, it is crucial for physicians to have the values sent to their mobile phones for reference purposes. The aim of this study was to develop an infrared thermometer with Short Message Service (SMS) feedback. The thermometer was built using an infrared sensor for contactless temperature measurement, a microcontroller for data processing, a liquid crystal display for user interface, and a GSM module to enable the transmission of SMS text alerts. The performance of the prototype was tested by comparing temperature readings against a commercially available certified infrared thermometer across 20 adult subjects in a controlled setting. The results showed strong correlation (R=0.976) between the readings from the developed thermometer and reference device, demonstrating comparable clinical accuracy in detecting temperature fluctuations. However, a small fixed bias of 0.2- 0.4°C was observed in the prototype readings due to calibration differences. Overall, this study successfully demonstrated a proof-of-concept infrared thermometer integrating contactless sensing and wireless transmission of temperature data via SMS. The prototype achieved accuracy comparable to commercial thermometers, indicating feasibility of creating a low-cost, mobile-connected infrared thermometer using this approach.

Strength Properties of Asphalt Mixture Produced with Polyvinyl Chloride (PVC) Modified Bitumen

2024-06-10T13:49:53+00:00

In recent time, more polyvinyl chloride (PVC) plastic are produced than what is currently being recycled, that contributes to the volume of waste. This occurrence prompted the exploration of polymer modified bitumen (PMB) to address the waste concern and thereby cuts cost in bituminous mix and improves pavement performance. This research evaluated the strength properties of asphalt mixture produced with polyvinyl chloride modified bitumen. Marshall method of mix design was used in the production of hot mix asphalt (HMA). Scanning Electron Microscopy (SEM), Fourier Transform Infra-red (FTIR) and Energy Dispersive X-Ray Spectrometry (EDS), used for microstructural examination and elemental analysis. These materials conform with its physical properties and characteristics. The shredded, grinded plastic revealed high binding properties when blend with bitumen. The percent incorporated was 2 - 10% PVC content and the Optimum Bitumen Content obtained was 10%, at 9.57kN for stability. The modified bitumen for penetration recorded at 68mm, which conformed with 60/70 grade bitumen, softening point recorded at 52oC, ductility was recorded at 107cm, specific gravity at 1.02, flash and fire point at 294oC and 306oC, solubility at 97% respectively. The properties were satisfactorily for grade 60/70 bitumen at 4% PVC by weight and be used as bitumen modifier for heavy traffic condition. Polyvinyl Chloride modified at 8 - 10%, be used at cold climates, while 2, 4, 6% PVC modified be used in warm regions. Therefore, the experiment proved these materials with characteristics, stability and stiffness be used for pavement constructions.

Public Procurement Act and Project Time Outcomes in Nigeria

2024-05-18T18:26:01+00:00

The Public Procurement Act (PPA) 2007 established the Bureau of Public Procurement to regulate and monitor the public procurement process to successfully deliver projects in Nigeria. The enactment of the Act has not produced the desired intentions due to a number of factors. The aim of this study was to investigate the operation of the PPA with a view to enhance project outcomes in the Nigerian construction sector. The specific objectives were to find out the level of awareness and compliance with the Act in Nigeria; and to establish the relationship between PPA and the time outcome of construction projects. Descriptive survey research was adopted to carry out this study. The population of the study comprised construction professionals in Lagos, Nigeria. Questionnaires were administered to 150 construction professionals selected by purposive sampling technique in the study area. Frequency, percentage, mean score (MS) and standard deviation (STD) were used to analyze the data. The findings revealed moderate awareness and compliance with the Act in Lagos State. The study concludes that although there is moderate awareness and compliance with the PPA, the goals of enactment of the PPA have not been fully realized due to poor project outcomes in terms of time. The implication is that the Act should be revisited to ensure that the provisions and means of enforcement are adequate to realize the goals. It is recommended that continuous awareness of the PPA should still be encouraged to enhance project outcomes. This can be done by adequate publicity of the Act among professionals. Additionally, the government should enforce compliance of the Act in organizations that do not comply. This can be done by scrutinizing contractors’ tender documents to ensure the inclusion of the provisions of the PPA.

Hybrid Data Compression and Zonal-Based Green Algorithm: Towards User Battery Power Conservation in Device-To-Device Communication

2023-12-22T22:46:33+00:00

Owing to the rapid increase in data demand, the need for power saving in mobile communication is of great importance. This study proposes a combination of a zone-based technique, also known as the Zonal Based GrEEn (ZBGrEEn) algorithm, with the Lempel Ziv Welch (LZW) data compression algorithm in order to produce significantly more energy- efficient device-to-device (D2D) communication network. The system is modeled as a device- to-device communication between one primary transmitter (PT) and many primary receivers (PRs) located in various zones around the PT. The ZBGrEEn algorithm ensures that power allocation is optimally performed so that the target rate of each application needed by PRs is met. Both the transmission time and transmission power computed in the ZBGrEEn algorithm are minimized due to the reduced data size achieved by applying the LZW algorithm on the data. Simulation results show an increase in battery lifetime of mobile devices from 46.28% (achieved when ZBGrEEn algorithm is used alone) to 51% when ZBGrEEn is combined with LZW algorithm.

Application of Cassava-Peels and Palm-Oil-Sludge Digestate on Bean Crop for Sustainable Growth

2024-08-16T15:16:45+00:00

This study investigates the potential of using digestate, a byproduct of anaerobic digestion, as organic manure in sustainable agriculture. The digestate was processed using a constructed screw press, separating it into liquid and solid components, with the liquid stored at room temperature and the solid subjected to a 20-day solar drying process. Four experimental conditions were tested: a control group, soil with chemical fertilizer, soil with solid digestate, and soil with liquid digestate. A fertilization rate of 1 gram per kilogram of soil was used. Over two months, distinct growth patterns emerged, with the liquid digestate group showing the most significant advantages, concluding with 59 leaves compared to 46 leaves in the solid digestate group, 44 in the chemical fertilizer group, and 42 in the control group. However, statistical analysis indicated no significant difference between treatments (p-value: 0.9451). The liquid digestate group also demonstrated superior stem width and crop yield, achieving a total yield of 99 bean seeds. The study highlights the promise of integrating digestate as organic manure in sustainable agriculture. The use of an anaerobic digester and screw press offers a viable solution for waste-to-resource conversion. Despite the encouraging results, further research is recommended to optimize digestate composition and application methods tailored to specific crop needs. This research contributes to eco-friendly agricultural practices and supports the advancement of sustainable waste management and crop cultivation strategies.

Assessment of Timber Degradation by Wood-Fungus and Insects in Afghanistan’s Diverse Climatic Zones

2024-08-05T11:12:19+00:00

Wood has been a fundamental material throughout human history due to its versatility and performance. However, wood's susceptibility to biodeterioration, primarily due to fungi and insects, poses significant challenges. This study assesses timber degradation by wood fungi and insects across Afghanistan's diverse climatic zones, including arid, temperate, and cold mountainous regions. To address this, a multifaceted descriptive method for data collection has been employed. The findings reveal distinct impacts of climatic conditions on wood degradation. In the arid climatic zone, 7.3% of species were affected by wood-decay fungi, with 5.5% attributed to brown rot and 1.8% to white rot. Additionally, 52.7% of degradation was caused by wood-stain fungi, with 25.5% due to sap-stain, 3.6% to mold, and 23.6% by chemical stain. Furthermore, 40% of wood decay in this zone was caused by insects, with termites accounting for 30.9%, beetles 3.6%, and carpenter ants 5.5%. In the temperate zone, 49.6% of species were affected by wood-decay fungi, with 34.7% due to brown rot and 14.9% to white rot. Moreover, 40.4% of degradation was attributed to wood-stain fungi, with 19.8% due to sap-stain, 12.3% to mold, and 8.3% to chemical stains. Insect activity in this zone accounted for 10% of wood decay, with termites affecting 1.7%, beetles 7.5%, and carpenter ants 0.8%. In the cold mountainous region, 69.2% of species were affected by wood-decay fungi, with 51.6% due to brown rot and 17.6% to white rot. Additionally, 30.8% of degradation was caused by wood-stain fungi, with 12.1% due to sap-stain, 13.2% to mold, and 5.5% by chemical stains. Notably, no insect activity was found in the cold mountainous climatic zone, as the severe freezing conditions deter insect presence. The results highlight the need for sustainable forestry practices and effective timber preservation strategies tailored to specific climatic conditions to mitigate the adverse effects of wood fungus and insect degradation.

Experimental Evaluation of the Physical and Sorption Properties of Gmelina Arborea Timber for Development of Wood-based Materials

2024-09-11T09:35:11+00:00

The physical and sorption properties of wood are critical factors influencing its performance in various applications. These properties affect the strength and durability of wood products. Understanding these properties is essential for developing wood-based materials. This study focuses on the experimental investigation of Gmelina arborea timber to evaluate its sorption properties. The methodology involved a series of tests following ASTM, ISO, and BS standards to measure density, shrinkage and other various sorption properties. Key results showed a mean green moisture content of 141.28%, a basic density of 505.03 kg/m³, a dry density of 540.28 kg/m³, and a density at 12% moisture content of 555.17 kg/m³. The timber exhibits a volumetric shrinkage and swelling of 8.71% and 8.26%, tangential shrinkage and swelling of 5.19 and 4.96%, radial shrinkage and swelling of 3.72% and 2.82%, and longitudinal shrinkage and swelling of 1.19% and 0.48% respectively. The ratio of tangential to radial shrinkage was computed as 1.4, which indicates reliable dimensional stability of the timber. Gmelina arborea absorbs 94.7% water over a soaking period of 1272 hours and loses 83.18% moisture during drying to reach an equilibrium moisture content of approximately 12%. Therefore, Gmelina arborea shows good potential for use in the development of Engineered Wood Products such as Cross-laminated timber.