Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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Effect of the Sliding of Stacked Live Loads on the Seismic Response of Structures
Get PDFDynamic interaction between sliding live loads and the structure they act on is significant in the seismic analysis and design of the structure. The problem becomes more complex when the live loads are in the form of stacks. This paper presents a numerical model to simulate the dynamic interaction between a primary structure (PS) and a set of stacked bodies lying on it. Individual bodies in the stack were termed as secondary bodies (SBs) in this study. The lowest SB in the stack interacts with the structure through friction. Similar frictional forces also exist between different levels of the stack. This numerical model was verified with a Finite Element model. A parametric study was performed on the seismic response by varying the dynamic properties of the structure and SBs. The energy dissipation is found to be significant due to sliding within the stack. A novel methodology is proposed to calculate a modified structural period (Tnew) of the structure to use in its design. It was found that the Tnew varies significantly with the structural period, mass ratios, and coefficients of friction. Finally, design equations are proposed to calculate the Tnew . Two Indian seismic hazard levels were considered for this study
Enhancement of light absorption using Nanoparticles Embedded Double layer Anti-Reflection Coating
Get PDFThe formation of nanoparticles embedded composite materials is a means for engineering the electrical and optical properties of thin films. This paper proposes the use of gold and silver nano-particles(NPs) to fine tune the effective index of two dielectric layers towards anti-reflection coating applications. Here, the upper layer is MgF2 (magnesium fluoride) and the lower layer is PMMA (Polymethylmethacrylate). The effect of embedding the nano-particles in the PMMA layer on the transmission spectrum is studied while tuning the concentration (volume fraction) and size of particles. With the increase in the size of the nano-particles there is a red shift in the transmission dip. On varying the nano-particle size the peak absorption can be shifted to the desired wavelength. Considering 50 nm silver nano-particle with the volume fraction ranging from 0.001 to 0.05, maximum transmission of light is observed under lower wavelength range of visible spectrum across the novel structur
Blockchain Technology, Technical Challenges and Countermeasures for Illegal Data Insertion
Get PDFBlockchain is a decentralized transaction and data management technology. It was developed for the world’s first cryptocurrency known as Bitcoin in 2008. The reason behind its popularity was its properties which provide pseudonymity, security, and data integrity without third-party intervention. Initially, most of the researches were focused on the Bitcoin system and its limitation, but later other applications of Blockchain e.g. smart contracts and licensing [1] also got famous. Blockchain technology has the potential to change the way how transactions are conducted in daily life. It is not limited to cryptocurrencies but could be possibly applied in various environments where any forms of transactions are done. This article presents a comprehensive overview of Blockchain technology, its development, applications, security issues, and their countermeasures. In particular, the security towards illegal data insertion and the countermeasures is focused. Our analysis of countermeasures of illegal data insertion can be combined for increased efficiency. After the introduction of the Blockchain and consensus algorithm, some famous Blockchain applications and expected future of Blockchain are deliberated. Then, the technical challenges of Blockchain are discussed, in which the main focus here is on the security and the data insertion in Blockchain. The review of the possible countermeasures to overcome the security issues related to data insertion are elaborated
Optimal Multi-Reservoir Operation for Hydropower Production in the Nam Ngum River Basin
Get PDFThis research aims to investigate optimal hydropower production of multi-reservoirs in Lao PDR and develop optimal reservoir rule curves. The Nam Ngum 1 and 2 (NN1 and NN2, respectively) reservoirs in the Nam Ngum River basin (NNRB), which is located in the middle of Laos, are selected as study areas. Mixed integer nonlinear programming (MINLP) is developed as an optimization model to maximize the hydropower production of joint reservoir operation of NN1 and NN2. The optimal operation rule curves are established by using the storage level estimated by the optimization model. Given the limited sideflow data, an integrated flood analysis system (IFAS) and water balance equation are used to simulate the sideflow into NN1 reservoir. A good fit is observed between the monthly streamflow simulated by IFAS and that calculated by the water balance equation. Compared with the observed data, the MINLP model can increase the annual and monthly hydropower production by 20.22% (6.01% and 14.21% for NN1 and NN2, respectively). The water storage level estimated by the MINLP model is used to build the operation rule curves. Results show that the MINLP model of multi-reservoir is a useful and effective approach for multi-reservoir operations and is expected to hold high application value for similar reservoirs in NNRB
Detection of Distorted Meat Image for Pork Grading System
Get PDFThis paper proposes a method that detects optical distorted areas (aka bubble) in pork images. By correctly identifying and discarding the images containing the unwanted bubbles, a significant improvement of pork image classification (or pork grading) in terms of accuracy has been achieved. The proposed bubble detection method relies on a particular set of image pre-processing techniques followed by morphological and region segmentation operations and is designed to attain the highest bubble detection accuracy for the detection of distorted images. Combining the proposed method with a typical pork image classification technique, the overall classification accuracy has been obtained as high as 96%.
Feasibility Analysis for the Implementation of Thermal Treatment Technologies for Municipal Solid Waste in Colombia
No full textThe purpose of this study is to determine the financial feasibility of electricity production projects in Colombia using thermal treatment technologies for Municipal Solid Waste (MSW), by assessing the generation potential, the costs associated with investment, operation and maintenance of infrastructure, and the environmental impacts in terms of CO2 emissions. The study is developed for three capital cities that reflect different conditions of production and characteristics of the MSW, which are: Bogotá D.C., Cartagena and Manizales. MSW production volumes were determined from information reported by public sanitation service providers, while their lower calorific value was estimated from a predictive model referenced in the literature. The results of the study indicate that the development of these technologies, in the three cities mentioned, would allow to contribute 2.309 GWh/year, corresponding to approximately 3,3% of the electricity demand in Colombia; likewise, they would reduce CO2 emissions by more than 3 million tons per year, compared to the emissions generated by the final disposal of waste in sanitary landfills. The plant located in the city of Bogota would have the best financial performance, with an internal return rate of 7,1%, under the assumptions raised in the study
A Novel Digital Discrete Manufacturing to Build up a 3D-Object
Get PDFThe paper present novel digital fabrication process that assembles building blocksto create a three-dimensional object. The system consists of an assembly robot and afabrication head installed at its tip. The head, consists of a vacuum gripper, an adhesiveextruder, and a camera, and is thus capable of gripping and releasing a building block,applying an adhesive, and determination of the position of things in the process. Thecalibration process and the design and build workflow for this technique are mentioned inthe paper. The process is a discrete fixtureless manufacturing process that gives faster speed,compared to both additive and subtractive manufacturing processes. Tiny mosaic pieces areused as building blocks and fabrication of a curved bridge model is used to demonstratehow this process works and its performance
Creating Added Value for Urban Transit in Developing Country: A Case Study of Transit-Oriented Development Project
Get PDFTransit-Oriented Development (TOD) is an approach of regional development in which there is a concept of integration between land, transportation, environment, and use. However, as a new idea in Indonesia, the development of TOD cannot be found yet. the TOD project for Jakarta LRT is the first idea for TOD implementation in Indonesia. From the results of the initial evaluation, it was found that the prepared TOD design of Jakarta LRT still refers to the development of conventional apartment buildings. The implication of this practice is that the benefits of TOD are not utilized, and regional development will not be in line with expectations. This research aims to improve the function of the project while fulfilling the characteristics of TOD by producing alternative designs that have added value. To achieve this goal, Value Engineering studies are used as the methods. After the benchmarking with case studies are done, the process of developing the existing TOD design is then carried out. As a result, the design of the conceptual development of TOD for Jakarta LRT is proposed as an alternative to the conventional property development, in which the benefits of TOD implementation can be obtained
Investigation on the Use Solar Thermoelectric Generator for Open Pond Cultivation with Heat Pipe Cooling
Get PDFAt present, most aquaculture ponds get a supply of dissolved oxygen from pumps or aerators that use electricity. Whereas in some places, farmers still experience infrastructure problems such as roads, ports, and electricity. Generally, the cultivation pond water level is 0.3-0.5ha, which can be rectangular or square. The large surface area of this pond has the potential to be utilized by its solar power. The thermoelectric module utilizes the Seebeck effect where if there is a heat difference between the two sides there will be an electric potential. The sun's heat can still be raised again by using a concentrator. Thermoelectric modules can produce electricity due to temperature differences on both sides. In aquaculture ponds, there is a lot of water that can be used to cool the thermoelectrics. One tool that can be used to deliver heat quickly is a heat pipe. Heat pipe is a passive device that has excellent heat transfer properties and high efficiency. In this research, heat pipes will be used as heat transfer media to cool the thermoelectric cold side. From the testing that has been done, the maximum voltage of the thermoelectric module is 3.77V obtained from a temperature difference of 67.57 °C
Use of Natural Rubber Latex (NRL) in Improving Properties of Reclaimed Asphalt Pavement (RAP)
Get PDFMany issues, especially cost, need to be looked at when a new asphalt materials are considered for road construction. One major factor that impacts the cost is the volatility in oil price and stock availability. Consequently, this factor affects both road construction and maintenance by creating uncertainty and financial challenge for Thai manufacturers. Furthermore, all economies, either national or local, depend on adequate road infrastructure and their sound maintenance for growth and development. One strategy for reducing the overall cost of road construction is through reclamation of existing pavement surfaces that are being repaired or replaced. A process of recycling asphaltic concrete pavement known as Reclaimed Asphalt Pavement (RAP) has been employed in many countries. However, one drawback associated with this practice is the costly investment in the mixing equipment which mechanically rejuvenates the old asphalt pavement by blending it with new asphalt binder. In addition to the high cost of investment, the required quality of the RAP has not been assured due to the lack of enough evidence. The addition of Natural Rubber Latex (NRL) to the process of the recycling asphalt pavement with the aim of reducing production costs and improving the quality of the RAP, offers a promising solution. This paper describes the results of an investigation into the properties of reclaimed asphaltic concrete mix with added NRL. The properties investigated include the Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR). The results show that properties of the NRL modified RAP mix meet the required engineering specifications. The results show that mixing NRL content of 5-15% by weight with RAP and cement content of 3-7% produced a mixture that meet the specification of Thailand Department of Highways in terms of UCS and CBR value for use in layers of pavement. Apart from the positive environmental impact of using recycle material of RAP, the economic and financial benefits to Thailand and rubber farmers make it worthwhile to use this NRL modified RAP for road construction and maintenance