Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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Enhancement of Stability in Alkali Solution of Polyethylene Terephthalate Fibers using Low-Dose Gamma Irradiation for Fiber-Reinforced Neutron Shielding Concrete
Get PDFPolyethylene terephthalate (PETE) fibers are used as a reinforcing agent to enhance concrete strength as well as to shield against thermal neutrons. This study increased the stability of PETE fibers in a strong alkali solution characteristic of concrete (pH = 12) using low-dose gamma radiation to induce crosslinking of the polymer chains. Results indicated that gamma ray dose of only 30 kGy resulted in the highest molecular weight, tensile strength and degree of crystallinity of PETE fibers with size 1.3 D. The surface topology using SEM micrography were also evaluated. An accelerated age testing revealed that these radiation-treated fibers will maintain their mechanical strength in concrete for up to at least 60 months. Thermal neutron attenuation test of fiber-reinforced concrete (FRC) indicated that the degree of thermal neutron shielding increased with increasing PETE fiber content, and that at 0.3% fiber content, FRC exhibited the highest thermal neutron attenuation of about 60% compared to unreinforced concrete. Therefore, these FRCs can readily be utilized as an effective neutron shielding material for nuclear and radiation applications to enhance radiation safety
Carbon Dioxide Capture from Flue Gas Using a Potassium-Based Sorbent in a Circulating-Turbulent Fluidized Bed
Get PDFThis research aimed to study the carbon dioxide (CO2) capture process using a potassium-based solid sorbent in a circulating fluidized bed riser (CFBR). The solid sorbent in this study was potassium carbonate on gamma alumina supporter (K2CO3/g-Al2O3). The hydrodynamics under a circulating-turbulent fluidized bed (C-TFB) regime occurred when the gas velocity was 1.00 m/s and could promote a solid sorbent distribution, with transition and transport velocities of 0.82 and 2.22 m/s, respectively, giving a uniform solid volume fraction distribution of 0.15 along the CFBR for the CO2 capture process. The study started with finding the operating condition in the riser so that the particle flowed in the reactor in the C-TFB regime. In addition, the kinetic of the adsorption under C-TFB flow regime in the riser was studied and the kinetic parameters corresponding to C-TFB flow regime were determined using deactivation kinetic model
Simultaneous Parameter Tuning of PSS and Wide-Area POD in PV Plant using FPA
Get PDFIn future power grid scenario, large-scale renewable energy based on power plant will be one of the main generations. Among renewable based power plant type, large-scale photovoltaic (PV) plant becoming more popular as they could provide zero emission and sustainable energy. However, even though PV plant could contribute positive impact to the environment, they could also contribute negatively to the power system. Large-scale PV generation came with different dynamic and zero inertia characteristic due to the application of the power electronic devices. Furthermore, PV plant has also drawback in terms of intermittent power output due to the uncertainty of the sources. Those handicaps could deteriorate the stability performance of power system especially oscillatory stability. Adding power system stabilizer (PSS) to the systems is one of the approaches for handling the oscillatory stability. However, with integration of PV plant in the systems, PSS alone is not enough to handle the oscillatory problems coming from various sources such us from PV plant dynamic. Hence, utilizing wide-area power oscillation damping (POD) as PV plant supplementary controller is inevitable. Hence, this paper proposes simultaneous parameter tuning between PSS and wide-area POD in PV plant using flower pollination algorithm (FPA) as the optimization method. The two-area power system is employed to evaluate the performance of PSS and POD using FPA. From the results, it is found that the proposed method could enhance the oscillatory stability of the system
A Study on Local Knowledge in Adaptation to Landslide Disasters in Sri Lanka
Get PDFNatural disasters are unforeseen events which occur at hydrologic, geologic, and atmospheric origins. The Policy-makers still rely on mitigation strategies based on scientific approaches. However, many scholars had emphasized the importance of incorporating local knowledge and related practices for disaster risk management. In that context, this study investigates the local knowledge in adaptation to mitigate the landslides disaster situations by studying a village in Sri Lanka which is located at the central region of Sri Lanka which is vulnerable for landslide disasters. Landslides is one of the severe types of disasters in hilly terrains and which cause to loss of lives and property damages especially in Asia region. This study employed the field surveys, questionnaire surveys and semi structured interviews for data collection. The findings of the research indicate how the local knowledge-based practices in settlement layout & planning, landscaping had enhanced disaster adaptation level of the community. Further the local knowledge-based value systems act as a strong mechanism in identifying early signs of landslide disasters. Finally, the paper discusses the possibilities of upscaling such local practices for mainstream disaster management practices
Evaluation of Economic Damages on Rice Production under Extreme Climate and Agricultural Insurance for Adaptation Measures in Northeast Thailand
Get PDFIn northeast Thailand, the irrigated agricultural land was only 7.6% (in 2012) of total and others were classified as rain-fed so that climate change makes agricultural production unstable and also makes negative impact to the societies and economics in rural area. To mitigate these issues, it is desirable to develop enhanced adaptation measures. In this study, we focused on weather induced economic damages and effectiveness of index-based insurance system in Northeast Thailand. Firstly, we evaluated how affect the seasonal rainfall amount and patterns on rice yield and production through regression analysis by using the meteorological and agricultural statistic data. 8 province had positive correlation R>0.3 with Jul-Sep accumulated rainfall. And then, probability analysis was applied to monthly rainfall which was employed for insurance index value. As a result, setting amount and periods of insurance index was suitable. Secondly, household survey was conducted to investigate farmer’s conditions of water use, cultivation, income balance. In recent year, agricultural damage on farmer’s income was not so large (less than 3%), because 65% of farmers income relied on non-agricultural sector. That might be the one reason of constraints of insurance sales
Redesign of Three-Echelon Multi-Commodity Distribution Network
Get PDFThis research studies the distribution network redesign of an actual electronics company. The problems are formulated based on multi-echelon capacitated Location Routing Problem (LRP) with two commodities: home products and service items. The objective function consists of three components: facility cost, closing cost of facility and transportation cost. We propose solution method based on clustering technique. The problem is decomposed into the Facility Location Allocation Problem (FLAP) and the Multi-Depot Vehicle Routing Problem (MDVRP). MDVRP is solved by clustering method and feed the results to the modified FLAP to allocate the demand nodes to facilities and configure all distribution networks, for the 2nd and 3rd echelon. The distribution is divided into five region zones. Previously, each region was operated independently but this research compares the solutions from solving each region independently and solving all five zones simultaneously. The results indicate that the proposed solution method can achieve computation time and total cost that are comparable to ones obtained from solving the problem to optimality. Exact approach can only solve small and medium problems, whereas the proposed solution method provides the acceptable solution of real-life largest problem in limit of computation time. Finally, we perform sensitivity analysis on the results
Application of Conditional Mean Spectrum in Nonlinear Response History Analysis of Tall Buildings on Soft Soil
Get PDFThe uniform hazard spectrum (UHS) and conditional mean spectrum (CMS) are commonly used as target spectra in selecting and scaling of records to be used in nonlinear response history analysis (NLRHA). When using CMS with tall buildings, CMS ground motions conditioned at multiple natural periods of the buildings should be considered. The application of CMS ground motions in NLRHA to estimate seismic demands for design of tall buildings located on soft-soil layers in Bangkok is investigated in this study. The seismic demands computed using multiple sets of CMS ground motions are compared with those computed using a single set of UHS spectral matching ground motions. Four existing tall buildings subjected to earthquake excitations in Bangkok were considered. The NLRHA was conducted using multiple sets of CMS ground motions, where periods of interest were considered at the periods closest to the periods of the first-three translational modes of the building in the direction of excitation. It was found that CMS ground motions conditioned at the higher-mode periods result in larger force demands than CMS ground motions conditioned at the fundamental period for some locations along the height of the building. The envelope of demands obtained by using multiple sets of CMS ground motions conditioned at different periods should be used in design but requires significant computational effort. Using UHS spectral matching ground motions can provide results close to such an envelope and reduce the computational effort significantly
The Analysis of Essential Factors Responsible for Loss of Labour Productivity in Building Construction Projects in India
Get PDFThe purpose of this paper is to find the essential factors influencing the loss of labour productivity (LP) in construction in India and substantiate these factors with naturalistic observation method in a building construction project. From the past studies, factors influencing the LP are specifically selected for the survey and statistically analyzed to form into defined group of factors. The influence of these factors is then correlated to the field level LP. For this, a case study is conducted using TMS technique to inspect factors influencing LP in an ongoing multi storied residential building construction site in Telangana State, India. The LP factors identified by survey analysis are quantitatively validated with the field study. It is noted that work characteristics, organizational characteristics, assured and safety work and workers management were responsible for 15% loss of LP in the field. Of these, major loss of about 11% is shown by work characteristics factors such as material delay and tools delay. This method can be utilized by construction personnel to measure the loss of LP with the data available from survey methods and also assists the construction personnel in making timely decisions towards the improvement of LP for various activities on the construction project sites
Acid-Pepsin Soluble Collagen from Saltwater and Freshwater Fish Scales
Get PDFExtraction and characterization of acid soluble collagen (ASC) and pepsin soluble collagen (PSC) from scales of Giant groupers (saltwater fish) and Nile tilapia (freshwater fish) were carried out in this research. Due to a higher protein content in scales, collagen yield extracted from the Giant groupers scales was higher than that of the Nile tilapia scales. The yield increased as extraction time increased for both ASC and PSC and pepsin extraction resulted in higher yields than acid extraction. Even though there were differences in collagen yields, collagen characteristics were independent of the scale sources but some differences were observed for the ASC and PSC. The peptide hydrolysis patterns of the ASC showed a wide range of molecular weights whereas all of the PSC had similar molecular weight of around 42 kDa. FTIR spectra showed that all the collagens remained the triple helical structure though ASC might be self-aggregated. From zeta potential analysis, net charge of zero was found at pH 3.2-4.0 and the dynamic light scattering suggested that the average particle sizes at pH 11-12 were around 100-200 nm. The denaturation temperatures (Tds) in a range of 35-42oC indicated that the collagens were considerably thermally stable
Preparation of VO2 Nanoparticles with Surface Functionalization for Thermochromic Application
Get PDFThis recent work investigates on the modification of metal oxide particles surface by the addition of amorphous coating layer. This core-shell structure is expected to decrease particles aggregation and increase their distribution in polymer matrix. VO2 particles were firstly prepared via hydrothermal process with 87% yield and XRD analysis showed that VO2 monoclinic was obtained with 100% of purity. XPS technique also showed that the surface of VO2 particles contains -OH group which is promising to form the strong covalent bond with silane coupling agent. The addition of functional groups on the surface of VO2 particles was then performed by the grafting of (3-Aminopropyl) triethoxysilane (APTES) via the silane anchoring group with 1:10 weight ratio VO2/APTES. The effect of solvent was also studied by using 10 ml of different solvent such as distilled water, ethanol and chloroform during surface coating. The TEM image clearly shows the presence of the thick organic layer on VO2 particles and as a result, the core-shell structure was perfectly identified. The round shape of coated VO2 particles was detected with small aggregation by SEM imageries. Furthermore, the presence of characteristic absorption band of C-H, Si-O-C, Si-O-Si and NH stretching in the FTIR spectra of coated VO2 particles confirmed the existence of APTES on the surface of VO2 particles prepared in distilled water and ethanol