Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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[RETRACTED ARTICLE] Blow Molding Simulation using Cross-Section Technique for Complex Shape Bottles
No full textThis research proposed the blow molding simulation method for determining of a cross-section thickness of bottles. The finite element method (FEM) was employed to simulate the extrusion blow molding process of the complex shape bottles. The full bottle shape of blow molding process had been attempted to simulate with a rectangular shape bottle for comparing with the cross-section technique. Particularly, the physical experiment of the blow molding process was performed to verify the FEM. The cross-section technique was obtained an accuracy result more than the full bottle shape simulation. The average error of full bottle shape simulation was 32.35% while the cross-section simulation obtained an average error of 17.02% when they were compared with the experimental data of blow molding process. The FEM of blow molding simulation using the cross-section technique which was developed in this research had been found the satisfactory method to determine the initial thickness of parison flowing through the extrusion die. It was advantaged to shape dies of the extrusion blow molding process in order to achieve the complex shape of bottles
User Characteristics and Effectiveness of a Park and Ride Facility in Bangkok
Get PDFAn experimental project was initiated in Bangkok in 2015 to set up Park and Ride facilities near transit stations as part of an effort to encourage transit use. Incentives were offered to prospective users, including free one-month trial and free transit trips. This paper provides evidence on user characteristics of one of the facilities and its effectiveness in time savings and reducing car travel. After the free-trial period ended, approximately 45% of the users discontinued their use. The results from interview surveys of both continuing and discontinued users confirm time savings and reduction in car travel for a majority of users who had relied solely on cars before the modal shift. But car travel distance increased for users who previously drove to other facilities or used public transport to access transit stations. The catchment area is found to be 23.6 km. We also developed a logistic regression model of the decision to continue using the facility even after the trial period. The modeling results imply that travel time and driving distance before and after using Park and Ride clearly influence decision-making. Users with longer travel time and driving distance before using Park and Ride tend to continue using the facility
Assessment of Satellite Rainfall Estimates as a Pre-Analysis for Water Environment Analytical Tools: A Case Study for Tonle Sap Lake in Cambodia
Get PDFTonle Sap Lake is the second main source of water supply and food security in Cambodia. However, this area is in the need for rainfall information which can cover the entire area for an accurate hydro-hydraulic modeling, climate modeling and other types of water or environment related modeling. In this case, Satellite Rainfall Estimates (SREs) would play a major role by filling out missing data where gauge observation is not available. The study aims to assess the spatio-temporal performance of two high resolution satellite products such as TRMM 3B42V7 and CHIRPS V.2. One-hundred and fifty four (154) stations around the Tonle Sap Lake and some close to the Mekong River were selected for the analysis within the study period of 2000 to 2004. After this, proper bias correction method is proposed. To do this, GIS and statistical indicators were used for the comparison. Both TRMM and CHIRPS provide a good correlation with the gauge. Around 90% of stations have CC varies from 0.5 to 0.9. In addition, the median bias of SREs are about 30 mm/month. Both satellite showed very similar pattern of bias spatially and temporally. This can be said that even though TRMM has the lower spatial resolution compared to CHIRPS, the performance of it is better. Moreover, TRMM have higher correlation when each of its cells was compared with the averaging of all stations within that cell. 25% of data that have extreme bias ratio maybe due to other underlying factors such as the distance from the station to the city, the soil elevation, landuse type, age of instrument, occurring of storm or drought that need to be taken into account for the further study
Climate Change and Landslide Risk Assessment in Uttaradit Province, Thailand
Get PDFThe incidents of sudden landslides in Thailand during the past decade have occurred frequently and more severely. The rain-triggered landslide hazard analysis is the focus of this research. The combination of geotechnical and hydrological data is used to determine permeability, conductivity, bedding orientation, overburden and presence of loose blocks. The regional landslide hazard mapping is developed using the Slope Stability Index SINMAP model supported on Arc GIS software version 10.1. The geological data can indicate the shear strength and the angle of friction values for soils above given rock types, which leads to the general applicability of the approach for landslide hazard analysis. In terms of hydrological data, the millimetres/twenty-four hours of average rainfall data are used to assess the rain triggered landslide hazard analysis in slope stability mapping. The Statistical Downscaling Model (SDSM) version 4.2, is used to assess the simulation scenario of future change; the study area is Uttaradit province, northern Thailand. The landslide hazard mapping will be compared and shown by areas (km2) for both present and future conditions under climate simulation scenarios A2 and B2 in Uttaradit province. The identified risk areas largely lie in hilly and mountainous terrain; which areas can be given additional protection during land use planning in order to reduce the risk of slope failure and the associated impacts on human activities
Flow Budget Change of Groundwater System under Climate Change in the Upper Central Plain, Thailand
Get PDFThe Upper Central Plain of Thailand, where farmers depended on both surface water and groundwater. Water allocated from the Bhumibol and Sirikit Dams are limited and caused water shortage in the dry years. Most farmers turn to use groundwater to supplement irrigation water in the dry years. This study aims to understand the flow budget change of groundwater under climate change scenario. The conjunctive use ratio of surface- as well as groundwater were investigated by field surveys and groundwater flow modeling, using the MODFLOW model to simulate the groundwater movement over the 10 years . The study used the bias-corrected MRI-GCM data to project the future climate conditions (during 2015 -2029 and 2075 - 2089) and assess the impact on flow budget change of groundwater system. The conjunctive use ratio were analyzed from surface water use and flow budget of groundwater system in term of water demand, rainfall, reservoir storage, groundwater recharge, groundwater storage, groundwater pumping. The study shows the flow budget change and conjunctive use ratio of each season and water year in the past and in the future under climate change scenarios
Effect of Diameter on Bond Failure of Steel Rebar Embedded into Concrete Using Epoxies at High Temperatures
Get PDFA series of pull-out tests were conducted to examine the bond deterioration of epoxy resins at elevated temperatures through the relationship between the critical temperature and bond stress. The steel rebars investigated were deformed bars with varying diameters of 12 mm, 16 mm, 20 mm and 25 mm. Two different types of epoxy resins were used. The test results show that the critical temperature for both types of epoxy resins tends to decrease with the increasing bond stress. In addition, the critical temperature is significantly lower for steel rebar with larger diameters. Meanwhile, the effect from varying types of epoxy resins on the bond characteristics is negligible. In order to illustrate the effect of rebar size, a mechanical model for the adhesive bonding stress between steel rebar and concrete interface at elevated temperatures is presented. The model provides good prediction of the bond stress at failure temperature.  
Identification of Handbrake Patterns of Young Motorcycle Riders in Thailand Using a Newly Invented Force Measuring Device
Get PDFThe paper aims at identifying handbrake control behavior of young Thai volunteer riders by focusing on small underbone-type of motorcycle using a newly developed force measuring device. The device has been invented to measure the handbrake force using the potentiometer through the fulcrum of hand control lever. Through calibration with the discrete static loads, the relation between the rotational hand control lever and the handbrake force has been determined. This technique is applicable for both hydraulic or cable handbrake systems. It has been employed to measure each rider’s handbrake force against both handbrake levers during brake application. Our sample included thirty volunteers and a professional rider. We conducted the tests based on transportation standard regulation of the United Nations Economic Commission for Europe (UNECE) regulation No. 78, under speed of 40 km/hr. Three types of handbrake patterns have been identified from these tests. Consequently, the force response characteristics from hydraulic and cable systems in motorcycle are notably different. The number of rider’s finger actuation and various patterns applied at the hand brake levers have been revealed to improve the brake skill from young motorcyclists
A Discrete-Continuous Method for Predicting Thermochemical Phenomena in a Cement Kiln and Supporting Indirect Monitoring
Get PDFThermochemical phenomena involved in cement kilns are still not well understood because of their complexity, besides technical difficulties in achieving direct measurements of critical process variables. This article addresses the problem of their comprehensive numerical prediction. The presented numerical model exploits Computational Fluid Dynamics and Finite Difference Method approaches for solving the gas domain and the rotating wall, respectively. The description of the thermochemical conversion and movement of the powder particles is addressed with a Lagrangian approach. Coupling between gas, particles and the rotating wall includes momentum, heat and mass transfer. Three-dimensional numerical predictions for a full-size cement kiln are presented and they show agreement with experimental data and benchmark literature. The quality and detail of the results are believed to provide a new insight into the functioning of a cement kiln. Attention is paid to the computational burden of the model and a methodology is presented for reducing the time-to-solution and paving the way for its exploitation in quasi-real-time, indirect monitoring
Cross-Sectoral Analysis of Water Usage in Thailand Using Input–Output Model
Get PDFThailand currently ranks third among the most water-intensive countries in the world. The percentage shares of water demand in the country’s agriculture, manufacturing, and service sectors, which are major economic sectors, are 75%, 3%, and 5%, respectively. With the continuous growth of the economy, the demand for water is steadily rising, while the expansion of water supply remains constrained by several factors and the water supply is also affected by climate change. This study uses the input–output model to examine the relationship between water usage and the economic system in Thailand in 2010. The constructed input–output model is the integration of the Leontief inverse matrix, the matrix of water usage, and the details of the gross domestic product (GDP). The model indicates the linkage between GDP expansion and water demand in both direct and indirect usage. The computation result obtained from the model indicates that the agricultural sector is the major water user, with its ratio of direct water use being the highest. The manufacturing sector records the highest ratio of indirect water use, which is influenced by its supply chain comprising the agriculture and service sectors. This model and its results may serve as the main foundation for the design of economic and environmental policies oriented toward optimizing water demand and supply. The model can also be extended and enriched with detailed mechanisms of economic behavior to allow further complex analyses such as water pricing policies
Effect of Water Hardness and pH on Adsorption Kinetic of Arsenate on Iron Oxide
Get PDFThe adsorption of arsenate on iron oxide particles was studied as a function of pH and hardness concentrations. The surface morphology of iron oxide particles was found to be rough and irregular. The major chemical compositions on iron oxide particles included Fe2O3 (96%). The optimum solution pH for adsorption was found to be 8.0. The equilibrium of arsenic concentration was reached after 30 min of contact time. The adsorption capacity was 124 µg/g. The adsorption isotherm was found to be either Langmuir or Freundlich. The adsorption kinetic was fitted well with pseudo-second order reaction with a rate constant (k2) ranging from 0.0062 to 0.0801 g/µg.min for 2 g to 20 g of iron oxide particles used. Calcium and magnesium concentrations did not significantly affect the adsorbed concentration of arsenic at equilibrium