Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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Internal Knowledge Sharing by Infrastructure Maintenance Engineers in Small and Medium Size Construction Companies in Japan
Get PDFIt is necessary to increase the capability of engineers to carry out maintenance management for keeping infrastructure safe and serviceable. Many regional training programs have been established to develop engineers into “maintenance experts.” While small and medium size construction companies and engineering consultants play an active role in infrastructure maintenance, they have limited human and economic resources for joining the training programs, so the sharing of knowledge acquired from the programs becomes important for improving the capability of the company as a whole. The objective of this research is to investigate how engineers who participated in regional training programs shared their knowledge inside their organization using an online questionnaire survey. It was found that leadership is an important factor for driving knowledge sharing activities, particularly for adapting the knowledge acquired from the training program to the company’s environment. However, the lack of experience serves as a barrier to the deeper transfer of knowledge, such as on-the-job training or seminars, as these methods of knowledge sharing require expert knowledge. For organizations to improve their knowledge sharing practices, it is necessary to consider the type of knowledge to be shared and the appropriate method for sharing, along with the improvement of the leadership for knowledge sharing in the organization
Supercritical Fluids Extraction of Valuable Compounds from Algae: Future Perspectives and Challenges
Get PDFAlgae (macro and micro) can be used to produce several high–value metabolites to supply industries as cosmetics, additives and pigments, among others. Those metabolites can have physiological and nutritional benefits for human and animal health. However, the availability of high–value metabolites from algae is still unaffordable due to traditional extraction techniques and their requirements of energy and use of pollutant solvents. Recently, green extraction technologies for the extraction of high–value metabolites have become more desirable due to their sustainability and environmental benefits. Supercritical fluids extraction, as green extraction techniques, has been widely applied for extraction of high–value metabolites from algae. Here, the highlight of supercritical CO2 and subcritical water on the extraction of bioactive compounds from macro– and microalgae was presented. The perspective and challenge for using supercritical CO2 and subcritical water on the algae extraction were also concluded
Improving Reliability of Synchrophasor Data Gathering Method Using Network Coding Technique
Get PDFWe consider synchrophasor data gathering method over the network of Phasor Measurement Units (PMUs) for Wide Area Measurement System (WAMS) applications. Although this network plays an important role to monitor, protect and control distribution electric grid, the research efforts in efficient data collection method are lacking in the literature. In this paper, we represent a novel data gathering approach using Network Coding technique and develop a mathematic model to predict the PMUs network reliability using our proposed model. It allows the PMU nodes in network to perform linear combination of many packets in order to improve the packet delivering ratio at the collector. We demonstrate our proposed method using a distribution grid test case and evaluate the performance by using Monter Carlo simulation. The numerical results have verified the effectiveness of our proposed method.We consider synchrophasor data gathering method over the network of Phasor Measurement Units (PMUs) for Wide Area Measurement System (WAMS) applications. Although this network plays an important role to monitor, protect and control distribution electric grid, the research efforts in efficient data collection method are lacking in the literature. In this paper, we represent a novel data gathering approach using Network Coding technique and develop a mathematic model to predict the PMUs network reliability using our proposed model. It allows the PMU nodes in network to perform linear combination of many packets in order to improve the packet delivering ratio at the collector. We demonstrate our proposed method using a distribution grid test case and evaluate the performance by using Monter Carlo simulation. The numerical results have verified the effectiveness of our proposed method
Effects of Pulverized Burnt Clay Waste Fineness on the Compressive Strength and Durability Properties of Blended Cement Concrete
No full textThe search for an alternative binder to cement, partially or wholly, continues to be on the increase. In this study, the fineness of pulverized burnt clay waste was evaluated as a factor that affects the compressive strength, chloride penetration and strength deterioration in sulphuric acid of its blended cement concrete. Pulverized burnt clay waste obtained from a source was divided into two different fineness portions using 75 and 150 µm sieves and classified as fine and coarse portions, respectively. Portland cement was replaced at 10 and 20% by weight with fine and coarse portions, separately. Additional mix containing 105% binder content consisting 5% excess fine and coarse portions at 10 and 20% cement replacement was also included. Chloride penetration was measured using the full immersion technique in 3% sodium chloride solution. The results revealed that increasing the fineness of pulverized burnt clay waste increases the compressive strength, reduced the chloride penetration and improves the acidic resistance of the blended cement concrete. These enhanced properties are due to the improved interfacial zone in the concrete resulting from increased specific surface area of the fine portion. Further improvement of the blended cement concrete properties can also be achieved with the use of 105% binder content containing 5% excess pozzolan beyond the conventional cement replacement level as observed in this study.The search for an alternative binder to cement, partially or wholly, continues to be on the increase. In this study, the fineness of pulverized burnt clay waste was evaluated as a factor that affects the compressive strength, chloride penetration and strength deterioration in sulphuric acid of its blended cement concrete. Pulverized burnt clay waste obtained from a source was divided into two different fineness portions using 75 and 150 µm sieves and classified as fine and coarse portions, respectively. Portland cement was replaced at 10 and 20% by weight with fine and coarse portions, separately. Additional mix containing 105% binder content consisting 5% excess fine and coarse portions at 10 and 20% cement replacement was also included. Chloride penetration was measured using the full immersion technique in 3% sodium chloride solution. The results revealed that increasing the fineness of pulverized burnt clay waste increases the compressive strength, reduced the chloride penetration and improves the acidic resistance of the blended cement concrete. These enhanced properties are due to the improved interfacial zone in the concrete resulting from increased specific surface area of the fine portion. Further improvement of the blended cement concrete properties can also be achieved with the use of 105% binder content containing 5% excess pozzolan beyond the conventional cement replacement level as observed in this study
Fire Resistance Performance of Reactive Powder Concrete Columns
Get PDFThis paper experimentally explores the fire resistance of reactive powder concrete (RPC) columns with varying steel and polypropylene (PP) fiber content. RPC is a concrete composition with the highest developed compressive strength and is incorporated with steel fibers that can improve the tensile strength and ductility of RPC structures. The fire resistance of RPC structures, however, has been disputed by engineers and researchers. Four columns with different weight contents of fiber were tested in fire for 30 and 60 minutes with a load applied afterwards. Then, the performance of RPC columns in elevated temperature was investigated, focusing on spalling depth, failure mechanism in fiber and residual strength. The results showed that increasing the volume fraction of steel fiber or the presence of PP fiber improves the fire resistance of the columns. However, the columns lost significant cross-sectional area and load capacity. With the knowledge that this research would provide, a better understanding for making decisions could be developed
Influences of Particle Size and Content on Deformation Resistance of Crumb Rubber Modified Asphalt using Dry Process Mix
Get PDFCrumb Rubber Modified (CRM) is one of techniques for improving asphalt mixture performance. There are two alternatives for applying crumb rubber (CR) to Hot Mix Asphalt (HMA), “Wet” and “Dry”. In the wet process, CR is added into hot asphalt cement in a factory, then CR-asphalt cement infusion is transported to a HMA plant for blending with hot aggregates. In the Dry process, CR is blended with hot aggregates and asphalt cement directly in a HMA plant. Although the dry process is considered less efficient due to lower infusion with asphalt cement, it offers some advantages that CR content can be independently controlled and higher amount of CR can be added into the HMA. This study focuses on dry process that uses CR modification by replacing some aggregate particles in mixture. HMA is blended with CR in 3 different sizes: 1.18 - 2.36 mm, 0.6 - 1.18 mm and smaller than 0.6 mm. The x-sized CR is added to the mixture in substitution of the same x-sized aggregate particles at the amount of 1% and 2% by the whole aggregate volume in the mixture. The mixtures’ performance in deformation resistance is represented by Wheel Tracking Slope (WTS). The results of Wheel Tracking tests on the specimens are enlightening. The mixture with CR particles smaller than 0.6mm shows excellent performance on deformation resistance, indicated by significantly lower WTS than others. Secondly, mixtures with higher amounts of CR have better performance than those with lower amounts. The mixture with 2% CR with smaller than 0.6 mm provides optimal performance at 2.1 times better than conventional HMA
Removal Performance of Silica and Solid Colloidal Particles from Chalcopyrite Bioleaching Solution: Effect of Coagulant (Magnafloc Set #1597) for Predicting an Effective Solvent Extraction
Get PDFSilicon dioxide is a compound containing two of the most abundant elements in Earth’s crust. One of the main obstacles for upright solvent extraction in a copper (bio)-hydrometallurgical production chain relates to the high silica content and solid colloidal particles in the pregnant leach solution (PLS) during the treatment chain. This study assesses by way of laboratory tests the removal performance of silica and fine colloidal particles in the bioleachate solution. Their concentration requirement at solvent extraction stage could not exceed 500 ppm and 75 ppm respectively. The contact time and three ratios (coagulant/PLS): 1/2; 1/1 and 1/3 settled. The removal method from coagulation with Magnafloc (set #1597) was performed by varying its concentration in contact with the bioleachate solution. The coagulation tests consisted of finding optimal conditions with the coagulant from 0.50 to 1000 ppm, while outcomes related to the interaction of bioleached solution with coagulant consisted of the search for the optimal ratio (volume ratio). From the above, the outcomes of coagulation tests revealed a removal optimisation of silica and solid colloidal particles from bioleachate solution, which has to be greater than 200 ppm, either 300 ppm and up, keeping a volume ratio of 1/1, for a recovery rate of 68% and 58% respectively for a removal efficiency of SiO2 and solids in suspension. A reduction of the phase separation time in aqueous continuity was observed from 230 to 148 seconds. It can be noted from the results mentioned above that the removal method will promote an effective copper solvent extraction stage, affecting the operating cost and greener environment with the possibility for recycling the organic wastes
Carbonized Briquettes as a Tool for Adding Value to Waste from Rain tree (Samanea Saman) and Coffee Ground/Tea Waste
Get PDFThe purpose of this research was to study the physical, environmental, and economic characteristics of carbonized briquettes from rain tree (Samanea saman) residues and coffee ground/tea waste with cassava starch (10% wt.). There were five treatments in this experiment. As a binder, 10%wt cassava starch was added to five ratios of rain tree residues to coffee ground/tea waste: RT100:CT0, RT75:CT25, RT50:CT50, RT25:CT75, and RT0:CT100. The physical properties of the carbonized briquettes were analyzed using ASTM methods. The results showed that the carbonized briquette made from 50% rain tree (Samanea saman) residues and 50% coffee ground/tea waste (RT50:CT50) had the highest calorific value (4,820.25 ± 9.97 Kcal/kg)—not significant at the 95% confidence interval—and highest shatter index (99.16 ± 0.20%). However, all ratios of rain tree residues to coffee ground/tea waste can produce carbonized briquettes for household use with convenience for transportation. In terms of economic performance, carbonized briquettes made from 50% rain tree (Samanea saman) residues and 50% coffee ground/tea waste (RT50:CT50) achieved the optimal payback period (approximately 6 months). Thus, making carbonized briquettes from rain tree residues and coffee ground/tea waste can be an alternative method of production to add value to biomass residue for use as raw materials to produce environmentally friendly fuel products
A Novel Configuration Fluidized Bed Reactor for Nitrate Reduction and Low Strength Anaerobic Wastewater Treatment
No full textIn this research, hydrodynamic behaviour in a novel fluidized bed reactor (FBR) was studied by using a residence time distribution (RTD) experiment. The RTD experimental result showed that the liquid flow pattern closed to plug flow behaviour. Moreover, the novel FBR was performed under low hydraulic retention time (HRT) operation (without internal recirculation), and its performance should be further investigated. There are two experimental approaches for wastewater treatment application. The first approach, a novel FBR, was performed for treating nitrate with a denitrification process at COD:NO3- - N of 1:1, 2:1, 3:1, 5:1 and 10:1. The highest nitrate removal efficiency was obtained at 99 ± 1%, with a ratio of COD:NO3- - N of 3:1. In the second approach, a novel FBR was evaluated in low strength anaerobic wastewater treatment. The novel FBR achieved 86 ± 6% of COD removal efficiency at an organic loading rate (OLR) of 5.6 g COD L-1 d-1.In this research, hydrodynamic behaviour in a novel fluidized bed reactor (FBR) was studied by using a residence time distribution (RTD) experiment. The RTD experimental result showed that the liquid flow pattern closed to plug flow behaviour. Moreover, the novel FBR was performed under low hydraulic retention time (HRT) operation (without internal recirculation), and its performance should be further investigated. There are two experimental approaches for wastewater treatment application. The first approach, a novel FBR, was performed for treating nitrate with a denitrification process at COD : NO3- - N of 1 : 1, 2 : 1, 3 : 1, 5 : 1 and 10 : 1. The highest nitrate removal efficiency was obtained at 99 ± 1%, with a ratio of COD:NO3- - N of 3 : 1. In the second approach, a novel FBR was evaluated in low strength anaerobic wastewater treatment. The novel FBR achieved 86 ± 6% of COD removal efficiency at an organic loading rate (OLR) of 5.6 g COD L-1 d-1
Analysis of Factors Affecting Multimedia Delivery for Elderly People
Get PDFThis study aims to apply appropriate information technology services for elderly people in order to fill the communication gap between the elderly, family members and friends by using a multimedia delivery platform. The aim is to improve the quality of life of the elderly people who live alone. It is intended to enhance the lives of elderly people to stay connected with family members, and friends by sending multimedia content including text, audio, image and video. We analyze the factors affecting the elderly person’s intention to use the platform by using Unified Theory of Acceptance and Use of Technology (UTAUT) model. The model evaluates the effectiveness of the multimedia delivery platform over the six key UTAUT constructs, namely, Performance Expectancy, Effort Expectancy, Social Influence, Facilitation Conditions, Perceived Security, and Experience and Voluntariness to Behavioral Intention. The analysis is twofold: to determine the factors affecting the intention of the elderly people in using the multimedia delivery platform, and to investigate how to reduce the communication gap between the elderly, family members and friends.This study aims to apply appropriate information technology services for elderly people in order to fill the communication gap between the elderly, family members and friends by using a multimedia delivery platform. The aim is to improve the quality of life of the elderly people who live alone. It is intended to enhance the lives of elderly people to stay connected with family members, and friends by sending multimedia content including text, audio, image and video. We analyze the factors affecting the elderly person’s intention to use the platform by using Unified Theory of Acceptance and Use of Technology (UTAUT) model. The model evaluates the effectiveness of the multimedia delivery platform over the six key UTAUT constructs, namely, Performance Expectancy, Effort Expectancy, Social Influence, Facilitation Conditions, Perceived Security, and Experience and Voluntariness to Behavioral Intention. The analysis is twofold: to determine the factors affecting the intention of the elderly people in using the multimedia delivery platform, and to investigate how to reduce the communication gap between the elderly, family members and friends