2031 research outputs found
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Assessment of E-Waste Management and Potential for Laptop Reuse and Recycling
Get PDFReusing and recycling laptops has many positive benefits, both environmentally and economically. Therefore, this study was conducted with the objectives of assessing (1) the current state of ownership, (2) the current state of use and disposal, and (3) quantifying the potential reuse and recycling of laptops for students at Can Tho University, Vietnam. Based on data collected by document review and face-to-face interviews with students, with a usage rate of 1 laptop per student, it is estimated that the whole of Can Tho University has 42,918 laptops in use. The actual use lifespan of the laptop is 5.28 years, lower than the expected lifespan of 6.8 years. The results of the correlation analysis show that the actual usage life does not have any correlation with the consumption behavior of students. In addition, the study estimates that 96.67% of laptops will be disposed of before 2031. In which, the potential for direct reuse is 2.33%, reuse with support is 88.33%, and recycling is 9.33%. The results show that universities have great potential to implement safe e-waste collection and treatment activities. Doi: 10.28991/CEJ-2023-09-06-013 Full Text: PD
Effect of Portland Cement on Mechanical and Durability Properties of Geopolymer Concrete at Ambient Temperature
Get PDFEnvironmental concerns have prompted researchers to focus on the development of alternative building materials like geopolymer concrete. However, their implementation requires curing beyond 60°C, which limits their application on building sites. This study aims to design a geopolymer concrete at room temperature (30 ± 5°C) in a laboratory in Burkina Faso using a metakaolin-based geopolymer binder activated by an alkaline solution of NaOH and natural aggregates. Portland cement type CEM I 42.5 was used by mass substitution (0 to 25%) of metakaolin to promote curing at ambient temperature. The samples were cured for 7 to 28 days and characterized for physical, mechanical, and durability properties. The results showed that the incorporation of 0 to 20% cement significantly improved the compressive strength from 9.9 to 30.5 MPa and the tensile strength from 1.2 to 2.2 MPa. However, Portland cement has various effects on the durability of geopolymer concrete. It reduces the porosity accessible by water from 15 to 13% and decreases the resistance to acid attack by increasing the mass loss from 2 to 7%. This confirms that common concrete types C20/25 or C25/30 can be casted using geopolymer concrete on the sites in Burkina Faso once their durability is confirmed. Doi: 10.28991/CEJ-2023-09-07-04 Full Text: PD
Estimation of Soil Moisture for Different Crops Using SAR Polarimetric Data
Get PDFSoil moisture is an essential factor that influences agricultural productivity and hydrological processes. Soil moisture estimation using field detection methods takes time and is challenging. However, using Remote Sensing (RS) and Geographic Information System (GIS) technology, soil moisture parameters become easier to detect. In microwave remote sensing, synthetic aperture radar (SAR) data helps to retrieve soil moisture from more considerable depths because of its high penetration capability and the illumination power of its light source. This study aims to process the SAR Sentinel-1A data and estimate soil moisture using the Water Cloud Model (WCM). Many physical and empirical models have been developed to determine soil moisture from microwave remote sensing platforms. However, the Water Cloud Model gives more accurate results. In this study, the WCM model is used for mixed crop types. The experimental soil moisture was determined from in-situ soil samples collected from various agricultural areas. The soil backscattering values corresponding to the different soil sampling locations were derived from Sentinel SAR data. Using linear regression analysis, the laboratory's soil moisture results and soil backscattering values were correlated to arrive at a model. The model was validated using a secondary set of in-situ moisture content values taken during the same period. The R2 and RMSE of the model were observed to be 0.825 and 0.0274, respectively, proving a strong correlation between the experimental soil moisture and satellite-derived soil moisture for mixed crop field types. This paper explains the methodology for arriving at a model for soil moisture estimation. This model helps to recommend suitable crop types in large, complex areas based on predicted moisture content. Doi: 10.28991/CEJ-2023-09-06-08 Full Text: PD
Derivation of Optimal Two Dimensional Rule Curve for Dualistic Reservoir Water-Supply System
Get PDFIn arid and semi-arid regions particularly vulnerable to climate change, optimizing the long-term operation of multi-purpose reservoirs is paramount. This study derived an optimum two-dimensional rule curve to jointly operate the parallel reservoirs of Mosul and Dukan, Northern Iraq. A hybridized optimization technique combining conventional dynamic programming with the shuffled complex evolution algorithm (SCE-UA) was developed to solve this problem. The results showed that the proportion of normal water supply areas increased from the beginning of the flood season (October) to its highest levels in April (58.77% of the total water supply area). The proportion decreased to its lowest in September (25.04% of the total water supply area). The newly derived 2D rule cure was compared with the current operation policy and was found to optimize the amount of water shortage by 21.1% during the operational period. It also reduced the shortage period and avoided catastrophic water shortages during droughts. In addition, the developed model optimized the amounts of water more than the joint water requirements, suffering from a significant deficit in meeting the demand during some months of the operational years. As a result, the storage in each reservoir was improved and thence can be adapted to face water shortages during future climate changes. This study proved the new hybridized model's applicability and can serve as a tool for sustainable water management. Doi: 10.28991/CEJ-2023-09-07-016 Full Text: PD
Analysis of Launcher's Productivity in Erection Girder Using Time Motion Study Method
Get PDFErection girder is one of the determinants of the success of bridge and road work, so in its implementation, it is of concern to many parties. Apart from lifting work that uses heavy equipment with a large capacity, it is also due to the high risk of erection work. Since using heavy equipment as a tool for the erection girder, then closely related to productivity and work time. Many factors affect the productivity of heavy equipment, and one of them is time, so a well and measurable work plan is needed. This study aims to provide solutions to problems regarding the productivity of the erection girder launcher method with a time motion study analysis for each work cycle. Time Motion Study is calculated using collected data from time and productivity records. The analysis model has been carried out with the amount of data of 58 erection girder cycles with the specification of Girder Profile I with 16 meters, 30 meters, 40 meters, and 60 meters in length. The modeling results are in the form of productivity nomograms and optimal productivity of the erection girder launcher method. The optimal productivity of a 16-meter girder is 0.901 girder/hour, 30 meters girder is 0.692 girder/hour, a 40 meters girder is 0.443 girder/hour, and 60 meters girder is 0.340 girder/hour. In this study, there are some renewals from other studies. From this study, it might be known about factors that affect the productivity of erection girders, such as the distance of the girder's stockyard, the girder's length, and erection time. Doi: 10.28991/CEJ-2023-09-08-06 Full Text: PD
Effect of Curing Temperature on Mechanical Properties of Sanitary Ware Porcelain based Geopolymer Mortar
Get PDFThe objective of this study was to investigate the effect of curing temperature on the mechanical properties of sanitary ware porcelain powder-based geopolymer paste and mortar under various curing temperatures. The setting time, porosity, water absorption, and compressive strength of specimens mixed with alkaline concentrations of 8M, 10M, 12M, and 14M were compared. All mortar cube (50í—50í—50 mm) specimens were placed into drying ovens for 24 hours at 60°C, 75°C, 90°C, and 105°C, respectively. The specimens were then air-cured for 1, 3, 7, 14, and 28 days. The results showed that the elevated curing temperature accelerated the polymerization process of the porcelain geopolymerization reaction. The setting time varied between 89 mins and 380 mins. It showed variability depending on alkaline concentration and initial curing temperature. The setting time of pastes decreased when alkaline concentrations increased. An increasing temperature in the drying oven decreased the initial and final setting times. Similar to this, the rate of water absorption and permeability of porcelain-based geopolymer mortar specimens decreased with drying oven temperatures and increments in alkaline concentration. The lowest water absorption and porosity of the specimen were 2.1% and 15.7%, respectively. The compressive strength increased as drying oven temperatures and alkaline concentrations increased. The highest 28 day compressive strength was found in 14M specimens with 105°C curing temperatures. The ultimate compressive strength was 64.45 N/mm2. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were investigated to study the microstructural properties of the geopolymers. Doi: 10.28991/CEJ-2023-09-08-01 Full Text: PD
Historical Arch Bridges-Deterioration and Restoration Techniques
Get PDFHistoric buildings are the most valuable evidence of cultural heritage. They play an essential role in establishing a tangible link between the past and the present by understanding, interpreting, and tracing the epoch of civilization. Unfortunately, the high costs of restoration, vandalism, and arson take their toll. However, new technologies are having a positive impact on the restoration process and are becoming a suitable alternative to labor-intensive, expensive, and unsafe traditional inspections. Therefore, the role of non-destructive testing (NDT) as a new method is becoming more evident. Faro laser scanning, impact echo, impulse sound testing, and geoelectric tomography as non-destructive methods are leading to the inspection of historic structures to preserve their character. These new methods are representative of the development of non-contact techniques for the examination and documentation of structures. Non-destructive testing examines the internal and external structure of complex building components as well as defective areas, quantifies cracks, and detects near-surface moisture. The objective of this work is to identify new adventurous and traditional methods for the reconstruction of the Turkish arch bridges Dara-1 and Halilviran to determine the appropriate rehabilitation methods and their deterioration of construction materials, damage, and failure patterns. Bridge dimensions were measured using a Faro laser scanner, which allows inspectors to capture and evaluate data from bridges and structural components without permanently altering them. The laser captures bridge dimensions by scanning cross-sections of the structure in the horizontal and vertical planes. The data is exported in the form of point clouds that represent all visible aspects and actual dimensions of the bridge in 2D and 3D models. In comparison between traditional and laser scanning methods, the main advantages of the applied method are the time savings on-site and the creation of a three-dimensional model of the structure, which can be used to collect precise and accurate surface data of objects in a non-destructive manner. Doi: 10.28991/CEJ-2023-09-07-010 Full Text: PD
Evaluating Carbon Footprint in the Life Cycle Design of Residential Concrete Structures in Jordan
Get PDFThe construction industry is a significant source of greenhouse gas emissions, and there is a growing global interest in reducing the environmental impact of carbon dioxide emissions associated with building construction and operation. Concrete, the most commonly used material in construction, is known to release a substantial amount of environmentally harmful waste throughout its life cycle, including production, construction, operation, and demolition. The worldwide production and consumption of concrete contribute to approximately 5% of all human-related CO2 emissions each year. To assess the carbon footprint of concrete manufacturing and its application in construction projects, a comprehensive approach called life cycle assessment (LCA) is necessary. This paper presents a new process-based LCA approach to analyze carbon emissions and evaluate the carbon footprint of concrete from raw material extraction to the end-of-life stage. To address carbon emissions throughout the life cycle of concrete structures in the Middle East, the study adopts a case study approach, focusing on selected concrete structures in Jordan. The findings from these case studies highlight that the operational phase of concrete structures is the primary contributor to carbon emissions. By thoroughly examining the carbon cycle within structures and their interactions with the surrounding ecosystem, significant reductions in CO2 emissions, environmental deterioration, and its consequences can be achieved. Doi: 10.28991/CEJ-2023-09-07-07 Full Text: PD
Post Fire Behavior of Structural Reinforced Concrete Member (Slab) Repairing with Various Materials
Get PDFOne of the most significant building materials used to build a variety of infrastructure, military, and civil structures is concrete. It can effectively withstand fire mishaps for a long period of time. This study employs a finite element simulation approach in Three steps: the first involves applying mechanical loading, the second involves applying mechanical and thermal loading; and the third involves strengthening the damaged model. Two different strengthening procedures were used to evaluate the performance of the fire-damaged slab. Two types of strengthening techniques”carbon-fiber-reinforced polymer (CFRP) sheet and slurry-infiltrated fibrous concrete (SIFCON) jacketing”were used. Studying the performance of SIFCON and CFRP together and in two different thicknesses of each for repairing both normal and high-strength concretes after fire exposure is considered limited. An investigation of their behavior can provide insights into how effective the restoration of strength is. The study aims to assess how well various repair materials perform in restoring the durability and strength of reinforced concrete members after being exposed to fire. This will assist in determining the best materials for concrete repair after a fire. Results show that the enhancements by SIFCON with a thickness of 30 mm significantly improved many indices, including load displacement behavior, ductility, and absorption energy of the slab. Doi: 10.28991/CEJ-2023-09-08-013 Full Text: PD
Indoor Climate Prediction Using Attention-Based Sequence-to-Sequence Neural Network
Get PDFThe Solar Dryer Dome (SDD), a solar-powered agronomic facility for drying, retaining, and processing comestible commodities, needs smart systems for optimizing its energy consumption. Therefore, indoor condition variables such as temperature and relative humidity need to be forecasted so that actuators can be scheduled, as the largest energy usage originates from actuator activities such as heaters for increasing indoor temperature and dehumidifiers for maintaining optimal indoor humidity. To build such forecasting systems, prediction models based on deep learning for sequence-to-sequence cases were developed in this research, which may bring future benefits for assisting the SDDs and greenhouses in reducing energy consumption. This research experimented with the complex publicly available indoor climate dataset, the Room Climate dataset, which can be represented as environmental conditions inside an SDD. The main contribution of this research was the implementation of the Luong attention mechanism, which is commonly applied in Natural Language Processing (NLP) research, in time series prediction research by proposing two models with the Luong attention-based sequence-to-sequence (seq2seq) architecture with GRU and LSTM as encoder and decoder layers. The proposed models outperformed the adapted LSTM and GRU baseline models. The implementation of Luong attention had been proven capable of increasing the accuracy of the seq2seq LSTM model by reducing its test MAE by 0.00847 and RMSE by 0.00962 on average for predicting indoor temperature, as well as decreasing 0.068046 MAE and 0.095535 RMSE for predicting indoor humidity. The application of Luong's attention also improved the accuracy of the seq2seq GRU model by reducing the error by 0.01163 in MAE and 0.021996 in RMSE for indoor humidity. However, the implementation of Luong attention in seq2seq GRU for predicting indoor temperature showed inconsistent results by reducing approximately 0.003193 MAE and increasing roughly 0.01049 RMSE. Doi: 10.28991/CEJ-2023-09-05-06 Full Text: PD