Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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Bark Extract of Lantana camara in 1M HCl as Green Corrosion Inhibitor for Mild Steel
Get PDFLantana camara, an invasive species that adversely affects habitant, bioregions and environment has been studied as corrosion inhibitor. Methanolic extract of barks of Lantana camara in 1 M hydrochloric acid was tested as corrosion inhibitor on mild steel using potentiodynamic polarization technique. The corrosion inhibition efficiency of extract varied with concentration of extract and immersion of time. The inhibition was found to increase with increase in concentration of the extract. The polarization behavior of mild steel revealed that maximum inhibition efficiency is 97.33 % and 89.93 % respectively in the 1000 and 200 ppm concentration of the inhibitor respectively. The results showed that the extract of the barks of Lantana camara served as a mixed type inhibitor
Applications, Manufacturing and Thermal Characteristics of Micro-Lattice Structures: Current State of the Art
Get PDFMicro-lattice structures are emerging as multi-functional devices. They possess excellent heat transfer capabilities, energy absorption abilities, vibration control abilities, etc. The higher surface area to volume ratio of micro-lattice structures makes them suitable for heat transfer applications where compact and lightweight heat transfer mechanism is necessary such as in case of space and transportation. The heat transfer and mechanical load-bearing properties of micro-lattice structures can be tailored by altering several parameters such as the lattice strut angle, node-to-node spacing, the diameter of the strut, etc. In this paper, micro-lattice structures, their manufacturing methods, applications are reviewed and a passive heat transfer mechanism consisting of micro-lattice heat pipe is proposed for the battery thermal management system in electric vehicles
Design of Hip Simulation Machine for Hip Labrum Testing
Get PDFThe acetabular labrum is the connective tissue between femoral head and hip joint that acts like a shock absorber. Labral injury could happen after hip dislocation or internal derangement such as femeroacetabular impingement (FAI) syndrome. The surgeon usually attempts to repair or reconstruct the torn labrum to obtain the native hip biomechanical loading. There has been no scientific evidence study for the different surgical techniques. Hip simulation machine was made to let a femur move in six conditions including step forward, step backward, abduction, adduction, internal rotation and external rotation. The hip was compressed with a force of half of the body weight (350 N). The purpose of this study was to study pressurization in three labral conditions including intact labrum, labral repair and labral reconstruction. The machine was designed and simulated by SolidWorks software. A device’s controller had two mode including a manual mode to set zero before an operation and automation mode to move in six conditions and compressed with a force of body weight. After the construction, the machine was tasted by using counterfeit pelvis and femur. The device was reformed before a real taste. Dissected cadaveric pelvises were used and measured pressure through the film piezoresistive load sensors. The testing result was helped the surgeon to make a decision in surgery process.The acetabular labrum is the connective tissue between femoral head and hip joint that acts like a shock absorber. Labral injury could happen after hip dislocation or internal derangement such as femeroacetabular impingement (FAI) syndrome. The surgeon usually attempts to repair or reconstruct the torn labrum to obtain the native hip biomechanical loading. There has been no scientific evidence study for the different surgical techniques. Hip simulation machine was made to let a femur move in six conditions including step forward, step backward, abduction, adduction, internal rotation and external rotation. The hip was compressed with a force of half of the body weight (350 N). The purpose of this study was to study pressurization in three labral conditions including intact labrum, labral repair and labral reconstruction. The machine was designed and simulated by SolidWorks software. A device’s controller had two mode including a manual mode to set zero before an operation and automation mode to move in six conditions and compressed with a force of body weight. After the construction, the machine was tasted by using counterfeit pelvis and femur. The device was reformed before a real taste. Dissected cadaveric pelvises were used and measured pressure through the film piezoresistive load sensors. The testing result was helped the surgeon to make a decision in surgery process
A General Equation Based on Entropy Generation Minimization to Optimize Plate Fin Heat Sink
Get PDFIn the present study, a new method based on entropy generation minimization was proposed to optimize plate fin heat sink. It is clear that the design of a heat sink is not straightforward and needs some secondary equations. Therefore, in the present study, dimensionless forms of equations were presented first and the effect of each dimensionless group on the entropy generation rate was studied deeply. Finally, a semi-analytical equation was proposed to relate dimensionless thickness to dimensionless fin height and Bi number as well. Interestingly, since no restricting assumption was made during derivation, this equation can be used for both natural and forced convection. Moreover, this equation is based on dimensionless parameters, so it is not limited to some specific geometries or working conditions. At the end, six examples showed benefits and ease of use of this equation. A fan curve was also used in optimizing a heat sink which is more realistic than using a specified free stream velocity
Experimental Study for the Effect of Pre-Cooling the Condenser Inlet Air of Split Type Air Conditioning Unit
Get PDFThe reduction of electric power consumption is considered to be a critical issue especially in the areas with elevated temperatures such as Iraq. In Basra city, the electric power consumption due to the air conditioning units (ACU) is so high. In this work, an evaporative cooling unit (ECU) is fabricated and tested where it is retrofitted with the condenser part of a split-type air conditioner. The experimental procedure was done in Basra engineering technical college located in west of Basra city. The present work is categorized in two cases. In case one, the system runs without using the ECU, while in case two the system is tested with ECU. The obtained results show that decreasing the inlet air temperature to the condenser will drop off the condensation and evaporation temperatures. Besides, it decreases the compression pressure ratio and increases the refrigerant mass flow rate. With this modification, it is found that the consumption power is decreased by 26% and COP increased by 90% compared with case one. The second law analysis of the modified system shows that using ECU will decrease most the exergy destruction and losses in the components. Only exergy destruction in the evaporator is increased. The system second law efficiency is improved by 69.5%
Incentive Contracts for Road Construction to Reduce Greenhouse Gas Emissions
Get PDFRoad constructions play a significant role in greenhouse gas (GHG) release into the atmosphere due to a large amount of materials consumption. To reduce emission has an effect on project costs. This research proposes an incentive measure named the Construction-Emission-Punishment (CEP) bidding method which offers emission reduction options and incentives for participating bidders. An equivalent bid price and a financial penalty will be specified in the construction contract as a part of this method. This penalty is applied when there is a failure to comply with binding obligations. The results show that the rates of the emission deduction from the six reduction options account for 0.115%-2.768% of the project cost. The case study also shows that a bidder who receives some emission deductions can be the winner. The effectiveness of the CEP method depends on the bid price gaps among the bidders and the emission deduction from the selected options
Estimation of Precipitable Water Using Numerical Prediction Data
Get PDFPrecipitable water (PW) is an important variable in the climate system. Interferometric synthetic aperture radar (InSAR) is a powerful remote sensing technique for measuring the topography and deformation of the Earth’s surface. However, variations in atmospheric water vapor content affect the accuracy of InSAR measurements. Therefore, it is important to understand the distribution of PW to mitigate atmospheric effects on remote sensing data. Herein, we estimated the PW distribution with high spatial resolution using numerical prediction data and digital elevation model (DEM) data from the Kanto region of Japan. We estimated the PW distribution at a resolution of 90 m from mesoscale model grid point value data while accounting for the difference in surface elevation within pixels using DEM data with a resolution of 90 m. The PW distribution at 90-m resolution could be estimated using the proposed method with good accuracy (root-mean-square difference within 4.0 mm) throughout the year. The proposed method provides high-resolution information on atmospheric water vapor content and its variation at 3-h intervals. This method is expected to be applicable in climate research and for the atmospheric correction of remote sensing data, which can improve the accuracy of remote sensing measurements
Recommender System Based on Expert and Item Category
Get PDFThe objective of this study was to introduce the recommender system based on expert and item category to match the right items to users. In this study, the expert identification was divided into 3 techniques which were 1) the experts from social network technique 2) the experts from the frequency of rating technique and 3) the experts from other user’s preferences. To filter the expert users by using the frequency of rating technique and the experts from other user’s preferences technique, data about item category is used. For evaluation in this study, the researcher used Epinion for the performance testing to find out errors and accuracies in the prediction process. The results of this study showed that all the presented techniques had mean absolute error score at 0.15 and 85 percentages of accuracy, especially the expert identification combining with item category, it can reduce 60 percentages of the duration of recommendation creatingThe objective of this study was to introduce the recommender system based on expert and item category to match the right items to users. In this study, the expert identification was divided into 3 techniques which were 1) the experts from social network technique, 2) the experts from the frequency of rating technique, and 3) the experts from other user’s preferences. To filter the expert users by using the frequency of rating technique and the experts from other user’s preferences technique, data about item category is used. For evaluation in this study, the researcher used Epinion for the performance testing to find out errors and accuracies in the prediction process. The results of this study showed that all the presented techniques had mean absolute error score at 0.15 and 85 percentages of accuracy, especially the expert identification combining with item category, it can reduce 60 percentages of the duration of recommendation creating
Assessment of the Driving Factors Affecting Electricity Consumption in Africa Using Index Decomposition Analysis and Satellite Derived Data
Get PDFInadequate electricity access limits human development and affects quality of life in Africa. Hence, the improvement of electricity access has become a cornerstone of the African energy policy. This study proposes the use of satellite derived data of nighttime lighting and population count and Index Decomposition Analysis (IDA) to identify the driving factors for changes in electricity consumption in Africa between 2000 and 2013. The results of decomposition analysis indicated that population growth throughout the continent resulted in increased electricity consumption, while other factors had different effects. The results of this study could contribute to the design of better energy policy to achieve sustainable development of the continent. Inadequate electricity access limits human development and affects quality of life in Africa. Hence, the improvement of electricity access has become a cornerstone of the African energy policy. This study proposes the use of satellite derived data of nighttime lighting and population count and Index Decomposition Analysis (IDA) to identify the driving factors for changes in electricity consumption in Africa between 2000 and 2013. The results of decomposition analysis indicated that population growth throughout the continent resulted in increased electricity consumption, while other factors had different effects. The results of this study could contribute to the design of better energy policy to achieve sustainable development of the continent. 
The Utilization of Concrete Residue with Electric Arc Furnace Slag in the Production of Geopolymer Bricks
Get PDFThe purpose of this study was to investigate the ratio of concrete residue (CR) and electric arc furnace slag (EAF) for the production of facing brick according to Thai Industrial Standard (TIS) 168-2546. These two industrial wastes contain high alumina and silica for the production of geopolymer bricks. In this research, CR and EAF were collected and homogenously mixed at the following CR to EAF ratios: 100 : 0, 90 : 10, 80 : 20, 70 : 30, and 60 : 40, with sodium hydroxide (10 M NaOH) and sodium silicate (Na2SiO3) solutions as catalysts. The ratio of Na2SiO3 to 10 M NaOH was 2.5. The mixtures were poured in molds (5 cm x 5 cm x 5 cm) and cured in plastic film at room temperature for 28 days. Then the mechanical and chemical properties of the brick specimens were analyzed, including dimensions and tolerances, wryness, deviation from right angles, water absorption, compressive strength, stains, holes, rails, and cracks, according to TIS 168-2546. The results showed that the optimum CR to EAF ratio of geopolymer bricks that was compliant to the TIS 168-2546 standard was 80 : 20, which had the highest compressive strength value (17.04 MPa) and the lowest water absorption (0.69%). Therefore, CR and EAF can be used as raw materials for facing bricks production