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Full-Text Articles in Civil Engineering

Isolation And Characterization Of Caffeine-Degrading Bacteria From Coffee Plantation Areas In Malaysia, Elvina Clarie Dullah, Mohd Fazli Farida Asras Dec 2023

Isolation And Characterization Of Caffeine-Degrading Bacteria From Coffee Plantation Areas In Malaysia, Elvina Clarie Dullah, Mohd Fazli Farida Asras

Makara Journal of Technology

Decaffeination by microbial degradation is currently the most optimal and low-cost approach, involving only microbial cells and/or their enzymes. The bacterium was characterized using a series of biochemical tests. Positive results were obtained from carbohydrate fermentation, citrate utilization, and catalase tests, while negative results were obtained from Voges-Proskauer (VP) and indole tests. Three different caffeine concentrations of 0.25%, 0.4%, and 2% were tested and measured through Gas Chromatography-Mass Spectrophotometry (GC-MS) analysis. The highest caffeine reduction (89.25%) was found when 0.25% caffeine was used in the media. Only a small amount of caffeine was reduced to 0.4% and 2%, with 34.78% …


Optimization Of The Building Envelope And Roof Shading To Reduce The Energy Consumption Of College Low-Rise Buildings In Indonesia, Nasruddin Nasruddin, Azimil Gani Alam, Mohammad Imroz Sohel Dec 2023

Optimization Of The Building Envelope And Roof Shading To Reduce The Energy Consumption Of College Low-Rise Buildings In Indonesia, Nasruddin Nasruddin, Azimil Gani Alam, Mohammad Imroz Sohel

Makara Journal of Technology

Energy consumption in buildings is a crucial concern globally, prompting researchers to explore innovative solutions to mitigate its impact. This study investigates the optimization of building envelopes and roof shading systems of existing buildings in Indonesia to realize notable energy savings. Multiple scenarios were explored, with modifications to building envelopes and roof shading, highlighting the overall thermal transfer value as a key parameter. Using EnergyPlus simulations, the efficacy of natural ventilation in corridors and roof shading modifications was assessed in reducing energy consumption. The findings revealed that renovating existing buildings by optimization of the building envelope and roof shading by …


Effect Of Lime Content, Curing Temperature, And Aging Condition On Low-Alkaline Concrete, Mahdi Parsa Pour, Reza Shaban Sharghi, Faezeh Nejati, Elmira Khaksar Najafi Dec 2023

Effect Of Lime Content, Curing Temperature, And Aging Condition On Low-Alkaline Concrete, Mahdi Parsa Pour, Reza Shaban Sharghi, Faezeh Nejati, Elmira Khaksar Najafi

Makara Journal of Technology

This study determines how curing temperatures, aging condition, and hydrated lime contents affect the unconfined compressive strength (UCS), modulus of elasticity, and workability of low-alkaline concrete. Samples were prepared in two different groups to determine the optimum hydrated lime content and aging conditions to assess the mutual effect of NaOH molarity and curing temperature, that is, 70 °C for 48 h or room temperature, on samples with and without lime. The results showed that the increase in hydrated lime content affected alkali concentration. The samples with lime exhibited a clear peak in UCS (6 M NaOH) compared with the continuous …


Challenges In Optimization For The Performance On Sustainability Dimensions In Reverse Logistics Social Responsibility, Sumarsono Sudarto, Katsuhiko Takahashi, Mochammad Dewo Aug 2023

Challenges In Optimization For The Performance On Sustainability Dimensions In Reverse Logistics Social Responsibility, Sumarsono Sudarto, Katsuhiko Takahashi, Mochammad Dewo

Makara Journal of Technology

Reverse logistics social responsibility is preferred as the most acceptable solution for addressing the challenges in stakeholders’ debate regarding social responsibility in supply chains because it involves as many actors as possible in the supply chain to perform social responsibility to achieve sustainability. This paper explores the challenges in achieving optimal policies in sustainability dimensions for collection and recycling facilities in reverse logistics. Sustainability dimensions include economic, environmental, and social aspects. The reverse logistics is modeled on System Dynamics, and a simplified statistical analysis using a contour chart is employed in numerical experiments. Results show a narrow area of optimal …


Investigating The Resistance Properties Of Concrete Containing Waste Carpet Fibers, Faezeh Nejati, Ali Mahboobi Aug 2023

Investigating The Resistance Properties Of Concrete Containing Waste Carpet Fibers, Faezeh Nejati, Ali Mahboobi

Makara Journal of Technology

This research was conducted with the aim of investigating the use of waste carpet fiber (WCF) and assessing the resistance properties of concrete. The main goal of this study was to investigate the effect of the internal processing of concrete containing WCF on increasing its resistance properties. At the same time, the secondary goals pursued in the research included determining the optimal percentages of carpet fibers in improving compressive strength, tensile strength, and bending strength. The materials used included cement, aggregates, water, WCF, and super lubricant. This research applied seven mixing designs: A, B1, B2, C1, C2, D1, and D2. …


Permeability Prediction For Expansive Soil Based On Physical Properties Using Artificial Neural Networks, Ferry Fatnanta, Imam Suprayogi, Nicola Rabb Ranata, Soewignjo Agus Nugroho, Agus Ika Putra Aug 2023

Permeability Prediction For Expansive Soil Based On Physical Properties Using Artificial Neural Networks, Ferry Fatnanta, Imam Suprayogi, Nicola Rabb Ranata, Soewignjo Agus Nugroho, Agus Ika Putra

Makara Journal of Technology

Permeability is a soil parameter related to the construction industry to understand the processes of infiltration, runoff, and settlement. The risk of testing errors is inevitable in permeability investigations, especially in expansive soils. Trial and error in permeability testing becomes difficult due to soils with small pore sizes and large shrinkage expansion. Several studies related to soil physical properties that affect permeability have been conducted. However, the correlation results obtained still have poor accuracy. Artificial neural networks (ANN) are machine learning systems that can change their structure to solve problems that are included in the system. The use of ANNs …