Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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Particulate Matter Monitoring Using Inexpensive Sensors and Internet GIS: A Case Study in Nan, Thailand
Get PDFThailand has faced environmental issues that affect people all the time. Haze from the forest fires for instance is concerned as national problem that we confront every year. To determine the severity of smog conditions being a consequence of haze fire in some areas cannot be easily done. Unmanned Aerial Vehicle (UAV) then could be easily used as a tool for surveying in such difficult burning areas. Furthermore having the environmental sensing devices developed and mounted on the UAV would be a worthy approach for monitoring environmental status in hazardous areas. This research was conducted to assemble the UAV and sensor device for measuring the environmental data including temperature, humidity and dust particle. The sensor was calibrated with reference devices. The field test was carried out in Nan province. Together with temperature, humidity and dust particle value, the location and time from GPS on UAV will be integrated correspondingly with environmental measuring data. Those entirely data will be imported to GIS and rendered in map form subsequently
The Influence of Parameters Affecting Mechanical Properties and Microstructures of Semi-Solid-Metal 7075 Aluminum Alloy by Using Friction Stir Spot Welding
Get PDFThis research aims to study the influence of parameters that affect the mechanical properties of semi-solid-metal 7075 aluminum alloy with friction stir spot welding process. The parameters fort this experiment such as rotation welding speed at 380, 760, 1240 and 2500 rpm and rotation welding time at 60, 90 and 120 seconds were employed respectively. The study found that the welded specimens at all the conditions can be welded very well. Moreover, friction stir spot welding process showed that the hardness in weld zone had an average value at 79.83 HV which is lower than the hardness of the base metal. The shear tensile strength of the welded specimens had the average value approximately 194.20 MPa at rotation welding speed of 1240 rpm, rotation welding time of 120 seconds and plunge of depth of 2 millimetres. The microstructure in the weld zone and thermal mechanical affected zone were deformed permanently. Therefore, friction stir spot welding process of this aluminum alloy provided good effects on mechanical properties. Statistical analysis showed that the coefficient of determination R-square was equal to 93.50 percent. This means that the variations of the experiments were controllable, such as equipment or other factors in the experiment. For the remaining, only 6.50 percent was uncontrolled factors
Groundwater and River Interaction Parameter Estimation in Saigon River, Vietnam
Get PDFThe Saigon River system is one of the largest resources contributing water supply for domestic and industrial fields in the Ho Chi Minh City and Binh Duong Province where the drought issue are occurring at downstream area in recent years. To manage the water resources in Saigon Basin effectively, the groundwater and river interaction parameter needs to be assessed systematically. However, in the past researches, the parameters seem to be less described with full understandings. In this study, a groundwater modeling of the main stream of Saigon River was applied to analyze groundwater and river interaction parameter along the river. The interaction layer was defined as a combined layer by materials of riverbed and materials of aquitard or aquifer. The values of conductance, through groundwater model calibration by piezometric heads during 2000 to 2007 at three cross-sections in Saigon River, were used to estimate the interaction parameter (KiM-1) at correlative cross-section. A function of interaction parameter with ratio of wetted length (Rw) was developed to estimate interaction parameter at each cross-section along Saigon River. When river cross-sections has no penetration to the aquifer and the materials of interaction layer consists of materials of riverbed and aquitard, the value of interactions is equal to 0.0003 d-1. In the other hand, the value will be reach to 0.254 d-1 when river cross-section has fully penetration to the aquifer. The interaction parameter function developed was applied to investigate the flow in and out between river and aquifer in the study area. In the upper part of Saigon River, river gained water from inflow of groundwater through riverbed (river gain) and lost water to groundwater (river loss) by outflow through the riverbed in the lower part during 2000 to 2007 and the river recharge to the first aquifer supplies to the second aquifer to supplement the aquifer storage discharged from the pumping
Designing Prediction Markets to Achieve Convergence Speed
Get PDFThe aim of this paper is twofold: to propose the model of artificial prediction markets that capture the characteristics of real prediction markets and to study the impact of key parameters on the performance of the proposed markets. In the experiments, the artificial markets are implemented and the market performance in terms of convergence speed is measured. Our experimental results show that the number of traders and the mean value of initial belief have no significant impact on the convergence speed. However, the trader’s memory size impacts negatively on the convergence because of its delay in adjusting to the true value. Finally, the external information transmission rate and the ratio of smart traders have positive impacts on the convergence of the prediction markets. The insights can assist a market maker in designing and constructing more efficient prediction markets
Study of Aeration and CO2 Absorption Using Filtration Membranes in Terms of Physical Properties and Mass Transfer Parameters
Get PDFHollow fiber membrane contactor is nowadays one of the alternative absorption processes for conventional bubble columns. In this work, the performances of microporous hollow fiber membranes for aeration and CO2 absorption were investigated. The membranes used in this work were adapted from filtration membranes which are significantly cheaper than conventional absorption membranes. The effects of operating variables such as average pore sizes, gas flow rates, liquid flow rates, amounts of hollow fiber membrane, and concentrations of chemical solution on the gas-liquid absorption rate were determined. For oxygen-water absorption, the overall mass transfer coefficient (kLa), which corresponding to the absorption rate, increased with the increase of membrane porous diameter. The kLa was also enhanced with the increase of the liquid flow rate and the number of membranes while the gas flow rate was rarely influent. For carbon dioxide absorption, the increase in liquid flow rate and the carbon dioxide concentration resulted in higher mass transfer rate. Moreover, adding sodium carbonate in absorbent improved the kLa value up to 2.2 folds, comparing with physical absorption. The comparison between membrane contractor and bubble column indicated that the utilization of filtration membranes had more efficiency comparing to bubble column due to its high surface area and adaptability when operating with the same size
Characteristics of Steel Fibre Reinforced High Strength Concrete Beams: Efficiency in Size Reduction for Flexure
Get PDFMechanical properties of concretes substituted with steel fibres and its relative merits on the size reduction of concrete specimens had been investigated in this study. Reinforcing efficiency of steel fibres on the flexural bending characteristics of thick and slender concrete sections had been experimentally verified. High strength concretes were produced using two different types of steel fibre anchorage profile consisting of single hooked and double hooked ends. The effects of steel fibres distribution in random and aligned direction were tested in various fibre concrete mixes substituted with 0.5% and 1.0% Vf of steel fibres. Fracture characteristics of various concrete specimens were tested using notched beam tests subjected to third point loading arrangement. Test results indicated a positive synergy of fibre profile and alignment which provided an effective bonding and increased fracture strength of fibre concretes. Fibre concretes incorporating double hooked end steel fibres showed higher fracture toughness (12.42 N-m) and fracture energy (955 (N/m) than single hooked steel fibre concretes. Better fibre-matrix bonding and alignment of steel fibres along beam axis have contributed for enhanced fracture resistance of fibre concretes as well as size reduction efficiency of fibre concrete sections
Basic Study on Detection of Deteriorated RC Structures Using Infrared Thermography Camera
Get PDFInfrastructures in the world get old in several decades of their service time. Falling-offs of parts of deteriorated structures were often reported and sometimes caused casualties in Japan and many other countries. When an earthquake occurs, in particular, deteriorated structures have higher possibility to be damaged or collapsed. Thus assessing the health condition of structures is one of the important topics in civil engineering. Considering a large number of structures that have been in service more than 40 years in Japan, efficient evaluation methods are requested. In this regard, non-destructive tests have high possibility to be applied to various structures without affecting their functions. Accordingly, this study focuses on the use of infrared thermography to detect internal deterioration of concrete structures. As a first step of investigation, thermography diagnosis, hammer sounding test and Schmidt rebound hammer test were carried out to detect internal deterioration of a concrete retaining wall located in the campus of Chiba University, Chiba, Japan, and the results were compared to evaluate the capability and accuracy of these diagnosis methods
Atmospheric Water Estimation Using GNSS Precise Point Positioning Method
Get PDFThe rapid adoption of the GNSS (Global Navigation Satellite System) technology in our modern daily life brings the opportunity to investigate its applicability to areas beyond positioning, navigation and timing, such as meteorology. Due to its high accuracy performance, GNSS (PPP) Precise Point Positioning has become an attractive tool to retrieve the precipitable water vapor (PWV) from the atmosphere. Apart of the GNSS observations, PPP PWV retrieval also requires surface pressure and temperature measurements to calculate precisely the wet part of the tropospheric delay and convert it to PWV. This research reports on the atmospheric water estimation using GNSS PPP method. GNSS observations from CUSV IGS tracking station are combined with IGS precise data in order to obtain the best PPP estimates. Forward and backward solutions are combined using a weighted normalized approach. In addition, observation data from two meteorological stations is used in PWV estimation. The numerical analysis covered the entire year of 2016. Our analyses show that PPP combined solutions are in very good agreement with IGS official products in terms of coordinates and zenith tropospheric delays. In addition, PPP PWV estimates display seasonal and temporal variation in the water content of the atmosphere. The PWV values over 65 mm were found to be from May to November, whereas they were on average 20% lower for the other months of the year. Furthermore, PWV estimates were found to be correlated with local rainfall events recorded at the meteorological stations. Our research concludes that GNSS data processing using PPP method provides high accuracy solution that may be used for retrieving reliably information about the water content in the atmosphere
Design of Decision Support System for Road Freight Transportation Routing Using Multilayer Zero One Goal Programming
Get PDFThe objective of this study was to develop a decision support system (DSS) to select the optimal road freight transportation route. This DSS is a proactive road freight transportation routing system which employs the standard criteria from the road freight transportation route’s physical characteristics for potential evaluation. The descriptions of potential scale were derived by the Delphi method based on accommodation of transportation. Moreover, the DSS can also calculate the relative weights of the decision criteria by Fuzzy Analytic Hierarchy Process (FAHP). Multilayer Zero One Goal Programming (MZOGP) is used as an optimization algorithm to select road freight transportation routes. The operation of this algorithm is to calculate the total deviation from three objectives: cost, time and, the deviation of road freight transportation route’s physical characteristic score which is calculated by comparing the route’s physical characteristic potential score with potential scores from users. The approach was tested on a realistic road freight transportation routing operation of a logistics service provider company. The empirical study showed that this DSS works successfully
Production Scheduling with Capacity-Lot Size and Sequence Consideration
Get PDFThe General Lot-sizing and Scheduling Problem (GLSP) is a common problem found in continuous production planning. This problem involves many constraints and decisions including machine capacity, production lot-size, and production sequence. This study proposes a two-phase algorithm for solving large-scale GLSP models. In Phase 1, we generate patterns with a specific batch size and capacity and in Phase 2, based on the patterns selected in Phase 1, we optimize the production allocation. Additionally, the external supplies are included in the formulation to reflect the real situation in business with limited resources. In this work, the justification of the formulation is based on the ability of solving and calculation time. The proposed formulation was tested on eight scenarios. The results show that the proposed formulation is more tractable and is easier to solve than the GLSP.The General Lot-sizing and Scheduling Problem (GLSP) is a common problem found in continuous production planning. This problem involves many constraints and decisions including machine capacity, production lot-size, and production sequence. This study proposes a two-phase algorithm for solving large-scale GLSP models. In Phase 1, we generate patterns with a specific batch size and capacity and in Phase 2, based on the patterns selected in Phase 1, we optimize the production allocation. Additionally, the external supplies are included in the formulation to reflect the real situation in business with limited resources. In this work, the justification of the formulation is based on the ability of solving and calculation time. The proposed formulation was tested on eight scenarios. The results show that the proposed formulation is more tractable and is easier to solve than the GLSP